WorldWideScience

Sample records for constrained spaces zeolites

  1. Zeolite thin films: from computer chips to space stations.

    Science.gov (United States)

    Lew, Christopher M; Cai, Rui; Yan, Yushan

    2010-02-16

    Zeolites are a class of crystalline oxides that have uniform and molecular-sized pores (3-12 A in diameter). Although natural zeolites were first discovered in 1756, significant commercial development did not begin until the 1950s when synthetic zeolites with high purity and controlled chemical composition became available. Since then, major commercial applications of zeolites have been limited to catalysis, adsorption, and ion exchange, all using zeolites in powder form. Although researchers have widely investigated zeolite thin films within the last 15 years, most of these studies were motivated by the potential application of these materials as separation membranes and membrane reactors. In the last decade, we have recognized and demonstrated that zeolite thin films can have new, diverse, and economically significant applications that others had not previously considered. In this Account, we highlight our work on the development of zeolite thin films as low-dielectric constant (low-k) insulators for future generation computer chips, environmentally benign corrosion-resistant coatings for aerospace alloys, and hydrophilic and microbiocidal coatings for gravity-independent water separation in space stations. Although these three applications might not seem directly related, they all rely on the ability to fine-tune important macroscopic properties of zeolites by changing their ratio of silicon to aluminum. For example, pure-silica zeolites (PSZs, Si/Al = infinity) are hydrophobic, acid stable, and have no ion exchange capacity, while low-silica zeolites (LSZs, Si/Al zeolites that have not been exploited before, such as a higher elastic modulus, hardness, and heat conductivity than those of amorphous porous silicas, and microbiocidal capabilities derived from their ion exchange capacities. Finally, we briefly discuss our more recent work on polycrystalline zeolite thin films as promising biocompatible coatings and environmentally benign wear-resistant and

  2. Shape space exploration of constrained meshes

    KAUST Repository

    Yang, Yongliang

    2011-12-12

    We present a general computational framework to locally characterize any shape space of meshes implicitly prescribed by a collection of non-linear constraints. We computationally access such manifolds, typically of high dimension and co-dimension, through first and second order approximants, namely tangent spaces and quadratically parameterized osculant surfaces. Exploration and navigation of desirable subspaces of the shape space with regard to application specific quality measures are enabled using approximants that are intrinsic to the underlying manifold and directly computable in the parameter space of the osculant surface. We demonstrate our framework on shape spaces of planar quad (PQ) meshes, where each mesh face is constrained to be (nearly) planar, and circular meshes, where each face has a circumcircle. We evaluate our framework for navigation and design exploration on a variety of inputs, while keeping context specific properties such as fairness, proximity to a reference surface, etc. © 2011 ACM.

  3. Zeolite

    Indian Academy of Sciences (India)

    49

    The unit cell volume change and the shift in XRD reflection positions. 18 showed a positive correlation with .... Molar ratios of the components in the gel with other conditions maintained during. 79 the synthesis of the MFI zeolite .... The reaction mixtures were analyzed by Gas Chromatography. 116. In the present study, the ...

  4. Large zeolites - Why and how to grow in space

    Science.gov (United States)

    Sacco, Albert, Jr.

    1991-01-01

    The growth of zeolite crystals which are considered to be the most valuable catalytic and adsorbent materials of the chemical processing industry are discussed. It is proposed to use triethanolamine as a nucleation control agent to control the time release of Al in a zeolite A solution and to increase the average and maximum crystal size by 25-50 times. Large zeolites could be utilized to make membranes for reactors/separators which will substantially increase their efficiency.

  5. Constraining de Sitter Space in String Theory.

    Science.gov (United States)

    Kutasov, David; Maxfield, Travis; Melnikov, Ilarion; Sethi, Savdeep

    2015-08-14

    We argue that the heterotic string does not have classical vacua corresponding to de Sitter space-times of dimension four or higher. The same conclusion applies to type II vacua in the absence of Ramond-Ramond fluxes. Our argument extends prior supergravity no-go results to regimes of high curvature. We discuss the interpretation of the heterotic result from the perspective of dual type II orientifold constructions. Our result suggests that the genericity arguments used in string landscape discussions should be viewed with caution.

  6. The bounds of feasible space on constrained nonconvex quadratic programming

    Science.gov (United States)

    Zhu, Jinghao

    2008-03-01

    This paper presents a method to estimate the bounds of the radius of the feasible space for a class of constrained nonconvex quadratic programmingsE Results show that one may compute a bound of the radius of the feasible space by a linear programming which is known to be a P-problem [N. Karmarkar, A new polynomial-time algorithm for linear programming, Combinatorica 4 (1984) 373-395]. It is proposed that one applies this method for using the canonical dual transformation [D.Y. Gao, Canonical duality theory and solutions to constrained nonconvex quadratic programming, J. Global Optimization 29 (2004) 377-399] for solving a standard quadratic programming problem.

  7. Environment determines evolutionary trajectory in a constrained phenotypic space.

    Science.gov (United States)

    Fraebel, David T; Mickalide, Harry; Schnitkey, Diane; Merritt, Jason; Kuhlman, Thomas E; Kuehn, Seppe

    2017-03-27

    Constraints on phenotypic variation limit the capacity of organisms to adapt to the multiple selection pressures encountered in natural environments. To better understand evolutionary dynamics in this context, we select Escherichia coli for faster migration through a porous environment, a process which depends on both motility and growth. We find that a trade-off between swimming speed and growth rate constrains the evolution of faster migration. Evolving faster migration in rich medium results in slow growth and fast swimming, while evolution in minimal medium results in fast growth and slow swimming. In each condition parallel genomic evolution drives adaptation through different mutations. We show that the trade-off is mediated by antagonistic pleiotropy through mutations that affect negative regulation. A model of the evolutionary process shows that the genetic capacity of an organism to vary traits can qualitatively depend on its environment, which in turn alters its evolutionary trajectory.

  8. Bayesian Variable Selection on Model Spaces Constrained by Heredity Conditions.

    Science.gov (United States)

    Taylor-Rodriguez, Daniel; Womack, Andrew; Bliznyuk, Nikolay

    2016-01-01

    This paper investigates Bayesian variable selection when there is a hierarchical dependence structure on the inclusion of predictors in the model. In particular, we study the type of dependence found in polynomial response surfaces of orders two and higher, whose model spaces are required to satisfy weak or strong heredity conditions. These conditions restrict the inclusion of higher-order terms depending upon the inclusion of lower-order parent terms. We develop classes of priors on the model space, investigate their theoretical and finite sample properties, and provide a Metropolis-Hastings algorithm for searching the space of models. The tools proposed allow fast and thorough exploration of model spaces that account for hierarchical polynomial structure in the predictors and provide control of the inclusion of false positives in high posterior probability models.

  9. Recovering a Probabilistic Knowledge Structure by Constraining Its Parameter Space

    Science.gov (United States)

    Stefanutti, Luca; Robusto, Egidio

    2009-01-01

    In the Basic Local Independence Model (BLIM) of Doignon and Falmagne ("Knowledge Spaces," Springer, Berlin, 1999), the probabilistic relationship between the latent knowledge states and the observable response patterns is established by the introduction of a pair of parameters for each of the problems: a lucky guess probability and a careless…

  10. Performance of Closely Spaced Point Absorbers with Constrained Floater Motion

    DEFF Research Database (Denmark)

    De Backer, G.; Vantorre, M.; Beels, C.

    2009-01-01

    The performance of a wave energy converter array of twelve heaving point absorbers has been assessed numerically in a frequency domain model. Each point absorber is assumed to have its own linear power take-off. The impact of slamming, stroke and force restrictions on the power absorption...... is evaluated and optimal power take-off parameters are determined. For multiple bodies optimal control parameters are not only dependent on the incoming waves, but also on the position and behaviour of the other buoys. Applying the optimal control values for one buoy to multiple closely spaced buoys results...

  11. Entropy considerations in constraining the mSUGRA parameter space

    International Nuclear Information System (INIS)

    Nunez, Dario; Sussman, Roberto A.; Zavala, Jesus; Nellen, Lukas; Cabral-Rosetti, Luis G.; Mondragon, Myriam

    2006-01-01

    We explore the use of two criteria to constraint the allowed parameter space in mSUGRA models. Both criteria are based in the calculation of the present density of neutralinos as dark matter in the Universe. The first one is the usual ''abundance'' criterion which is used to calculate the relic density after the ''freeze-out'' era. To compute the relic density we used the numerical public code micrOMEGAs. The second criterion applies the microcanonical definition of entropy to a weakly interacting and self-gravitating gas evaluating then the change in the entropy per particle of this gas between the ''freeze-out'' era and present day virialized structures (i.e systems in virial equilibrium). An ''entropy-consistency'' criterion emerges by comparing theoretical and empirical estimates of this entropy. The main objective of our work is to determine for which regions of the parameter space in the mSUGRA model are both criteria consistent with the 2σ bounds according to WMAP for the relic density: 0.0945 < ΩCDMh2 < 0.1287. As a first result, we found that for A0 = 0, sgnμ +, small values of tanβ are not favored; only for tanβ ≅ 50 are both criteria significantly consistent

  12. Constraining the loop quantum gravity parameter space from phenomenology

    Science.gov (United States)

    Brahma, Suddhasattwa; Ronco, Michele

    2018-03-01

    Development of quantum gravity theories rarely takes inputs from experimental physics. In this letter, we take a small step towards correcting this by establishing a paradigm for incorporating putative quantum corrections, arising from canonical quantum gravity (QG) theories, in deriving falsifiable modified dispersion relations (MDRs) for particles on a deformed Minkowski space-time. This allows us to differentiate and, hopefully, pick between several quantization choices via testable, state-of-the-art phenomenological predictions. Although a few explicit examples from loop quantum gravity (LQG) (such as the regularization scheme used or the representation of the gauge group) are shown here to establish the claim, our framework is more general and is capable of addressing other quantization ambiguities within LQG and also those arising from other similar QG approaches.

  13. Coordinated trajectory planning of dual-arm space robot using constrained particle swarm optimization

    Science.gov (United States)

    Wang, Mingming; Luo, Jianjun; Yuan, Jianping; Walter, Ulrich

    2018-05-01

    Application of the multi-arm space robot will be more effective than single arm especially when the target is tumbling. This paper investigates the application of particle swarm optimization (PSO) strategy to coordinated trajectory planning of the dual-arm space robot in free-floating mode. In order to overcome the dynamics singularities issue, the direct kinematics equations in conjunction with constrained PSO are employed for coordinated trajectory planning of dual-arm space robot. The joint trajectories are parametrized with Bézier curve to simplify the calculation. Constrained PSO scheme with adaptive inertia weight is implemented to find the optimal solution of joint trajectories while specific objectives and imposed constraints are satisfied. The proposed method is not sensitive to the singularity issue due to the application of forward kinematic equations. Simulation results are presented for coordinated trajectory planning of two kinematically redundant manipulators mounted on a free-floating spacecraft and demonstrate the effectiveness of the proposed method.

  14. Reachable Distance Space: Efficient Sampling-Based Planning for Spatially Constrained Systems

    KAUST Repository

    Xinyu Tang,

    2010-01-25

    Motion planning for spatially constrained robots is difficult due to additional constraints placed on the robot, such as closure constraints for closed chains or requirements on end-effector placement for articulated linkages. It is usually computationally too expensive to apply sampling-based planners to these problems since it is difficult to generate valid configurations. We overcome this challenge by redefining the robot\\'s degrees of freedom and constraints into a new set of parameters, called reachable distance space (RD-space), in which all configurations lie in the set of constraint-satisfying subspaces. This enables us to directly sample the constrained subspaces with complexity linear in the number of the robot\\'s degrees of freedom. In addition to supporting efficient sampling of configurations, we show that the RD-space formulation naturally supports planning and, in particular, we design a local planner suitable for use by sampling-based planners. We demonstrate the effectiveness and efficiency of our approach for several systems including closed chain planning with multiple loops, restricted end-effector sampling, and on-line planning for drawing/sculpting. We can sample single-loop closed chain systems with 1,000 links in time comparable to open chain sampling, and we can generate samples for 1,000-link multi-loop systems of varying topologies in less than a second. © 2010 The Author(s).

  15. Constraining the mSUGRA parameter space through entropy and abundance criteria

    International Nuclear Information System (INIS)

    Cabral-Rosetti, Luis G.; Mondragon, Myriam; Nunez, Dario; Sussman, Roberto A.; Zavala, Jesus; Nellen, Lukas

    2007-01-01

    We explore the use of two criteria to constrain the allowed parameter space in mSUGRA models; both criteria are based in the calculation of the present density of neutralinos χ0 as Dark Matter in the Universe. The first one is the usual ''abundance'' criterion that requieres that present neutralino relic density complies with 0.0945 < ΩCDMh2 < 0.1287, which are the 2σ bounds according to WMAP. To calculate the relic density we use the public numerical code micrOMEGAS. The second criterion is the original idea presented in [3] that basically applies the microcanonical definition of entropy to a weakly interacting and self-gravitating gas, and then evaluate the change in entropy per particle of this gas between the freeze-out era and present day virialized structures. An 'entropy consistency' criterion emerges by comparing theoretical and empirical estimates of this entropy. One of the objetives of the work is to analyze the joint application of both criteria, already done in [3], to see if their results, using approximations for the calculations of the relic density, agree with the results coming from the exact numerical results of micrOMEGAS. The main objetive of the work is to use this method to constrain the parameter space in mSUGRA models that are inputs for the calculations of micrOMEGAS, and thus to get some bounds on the predictions for the SUSY spectra

  16. Extreme climatic events constrain space use and survival of a ground-nesting bird.

    Science.gov (United States)

    Tanner, Evan P; Elmore, R Dwayne; Fuhlendorf, Samuel D; Davis, Craig A; Dahlgren, David K; Orange, Jeremy P

    2017-05-01

    Two fundamental issues in ecology are understanding what influences the distribution and abundance of organisms through space and time. While it is well established that broad-scale patterns of abiotic and biotic conditions affect organisms' distributions and population fluctuations, discrete events may be important drivers of space use, survival, and persistence. These discrete extreme climatic events can constrain populations and space use at fine scales beyond that which is typically measured in ecological studies. Recently, a growing body of literature has identified thermal stress as a potential mechanism in determining space use and survival. We sought to determine how ambient temperature at fine temporal scales affected survival and space use for a ground-nesting quail species (Colinus virginianus; northern bobwhite). We modeled space use across an ambient temperature gradient (ranging from -20 to 38 °C) through a maxent algorithm. We also used Andersen-Gill proportional hazard models to assess the influence of ambient temperature-related variables on survival through time. Estimated available useable space ranged from 18.6% to 57.1% of the landscape depending on ambient temperature. The lowest and highest ambient temperature categories (35 °C, respectively) were associated with the least amount of estimated useable space (18.6% and 24.6%, respectively). Range overlap analysis indicated dissimilarity in areas where Colinus virginianus were restricted during times of thermal extremes (range overlap = 0.38). This suggests that habitat under a given condition is not necessarily a habitat under alternative conditions. Further, we found survival was most influenced by weekly minimum ambient temperatures. Our results demonstrate that ecological constraints can occur along a thermal gradient and that understanding the effects of these discrete events and how they change over time may be more important to conservation of organisms than are average and broad

  17. The constrained space orbital variation analysis for periodic ab initio calculations

    International Nuclear Information System (INIS)

    Cruz Hernandez, N.; Zicovich-Wilson, Claudio Marcelo; Fdez Sanz, Javier

    2006-01-01

    The constrained space orbital variation (CSOV) method for the analysis of the interaction energy has been implemented in the periodic ab initio CRYSTAL03 code. The method allows for the partition of the energy of two interacting chemical entities, represented in turn by periodic models, into contributions which account for electrostatic effects, mutual polarization and charge transfer. The implementation permits one to carry out the analysis both at the Hartree-Fock and density functional theory levels, where in the latter the most popular exchange-correlation functionals can be used. As an illustrating example, the analysis of the interaction between CO and the MgO (001) surface has been considered. As expected by the almost fully ionic character of the support, our periodic CSOV results, in general agree with those previously obtained using the embedded cluster approach, showing the reliability of the present implementation

  18. Deactivation of Zeolite Catalyst H-ZSM-5 during Conversion of Methanol to Gasoline: Operando Time- and Space-Resolved X-ray Diffraction.

    Science.gov (United States)

    Rojo-Gama, Daniel; Mentel, Lukasz; Kalantzopoulos, Georgios N; Pappas, Dimitrios K; Dovgaliuk, Iurii; Olsbye, Unni; Lillerud, Karl Petter; Beato, Pablo; Lundegaard, Lars F; Wragg, David S; Svelle, Stian

    2018-03-15

    The deactivation of zeolite catalyst H-ZSM-5 by coking during the conversion of methanol to hydrocarbons was monitored by high-energy space- and time-resolved operando X-ray diffraction (XRD) . Space resolution was achieved by continuous scanning along the axial length of a capillary fixed bed reactor with a time resolution of 10 s per scan. Using real structural parameters obtained from XRD, we can track the development of coke at different points in the reactor and link this to a kinetic model to correlate catalyst deactivation with structural changes occurring in the material. The "burning cigar" model of catalyst bed deactivation is directly observed in real time.

  19. Constraining the mSUGRA (minimal supergravity) parameter space using the entropy of dark matter halos

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, Dario; Zavala, Jesus; Nellen, Lukas; Sussman, Roberto A [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (ICN-UNAM), AP 70-543, Mexico 04510 DF (Mexico); Cabral-Rosetti, Luis G [Departamento de Posgrado, Centro Interdisciplinario de Investigacion y Docencia en Educacion Tecnica (CIIDET), Avenida Universidad 282 Pte., Col. Centro, Apartado Postal 752, C. P. 76000, Santiago de Queretaro, Qro. (Mexico); Mondragon, Myriam, E-mail: nunez@nucleares.unam.mx, E-mail: jzavala@nucleares.unam.mx, E-mail: jzavala@shao.ac.cn, E-mail: lukas@nucleares.unam.mx, E-mail: sussman@nucleares.unam.mx, E-mail: lgcabral@ciidet.edu.mx, E-mail: myriam@fisica.unam.mx [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (IF-UNAM), Apartado Postal 20-364, 01000 Mexico DF (Mexico); Collaboration: For the Instituto Avanzado de Cosmologia, IAC

    2008-05-15

    We derive an expression for the entropy of a dark matter halo described using a Navarro-Frenk-White model with a core. The comparison of this entropy with that of dark matter in the freeze-out era allows us to constrain the parameter space in mSUGRA models. Moreover, combining these constraints with the ones obtained from the usual abundance criterion and demanding that these criteria be consistent with the 2{sigma} bounds for the abundance of dark matter: 0.112{<=}{Omega}{sub DM}h{sup 2}{<=}0.122, we are able to clearly identify validity regions among the values of tan{beta}, which is one of the parameters of the mSUGRA model. We found that for the regions of the parameter space explored, small values of tan{beta} are not favored; only for tan {beta} Asymptotically-Equal-To 50 are the two criteria significantly consistent. In the region where the two criteria are consistent we also found a lower bound for the neutralino mass, m{sub {chi}}{>=}141 GeV.

  20. On exploration of geometrically constrained space by medicinal leeches Hirudo verbana.

    Science.gov (United States)

    Adamatzky, Andrew

    2015-04-01

    Leeches are fascinating creatures: they have simple modular nervous circuitry yet exhibit a rich spectrum of behavioural modes. Leeches could be ideal blue-prints for designing flexible soft robots which are modular, multi-functional, fault-tolerant, easy to control, capable for navigating using optical, mechanical and chemical sensorial inputs, have autonomous inter-segmental coordination and adaptive decision-making. With future designs of leech-robots in mind we study how leeches behave in geometrically constrained spaces. Core results of the paper deal with leeches exploring a row of rooms arranged along a narrow corridor. In laboratory experiments we find that rooms closer to ends of the corridor are explored by leeches more often than rooms in the middle of the corridor. Also, in series of scoping experiments, we evaluate leeches capabilities to navigating in mazes towards sources of vibration and chemo-attraction. We believe our results lay foundation for future developments of robots mimicking behaviour of leeches. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Constraining the supersymmetric parameter space with early data from the Compact Muon Solenoid experiment.

    CERN Document Server

    Whyntie, Tom

    2011-01-01

    The year 2010 saw the Large Hadron Collider (LHC) collect 35.1 pb−1 of 7 TeV proton-proton collision data. This thesis reports on the work carried out by the candidate as part of the calculation of the first constraints placed upon the supersymmetric parameter space using measurements made with this data. In particular, the development and application of the kinematic techniques used to ensure that the search was robust to detector mismeasurements, inherent in any early phase of data-taking, are discussed. The Constrained Minimally Supersymmetric Standard Model (CMSSM) model is introduced to demonstrate how a supersymmetric model may extend the Standard Model of particle physics, and is used as the benchmark signal to examine how supersymmetry may manifest in 7 TeV proton-proton collisions. The role of kinematics in early searches for such signals is then discussed; given the final state topology of interest (particle jets and large missing transverse momentum), it is useful to explore how the event kinemat...

  2. Not so colourful after all: eggshell pigments constrain avian eggshell colour space.

    Science.gov (United States)

    Hanley, Daniel; Grim, Tomáš; Cassey, Phillip; Hauber, Mark E

    2015-05-01

    Birds' eggshells are renowned for their striking colours and varied patterns. Although often considered exceptionally diverse, we report that avian eggshell coloration, sampled here across the full phylogenetic diversity of birds, occupies only 0.08-0.10% of the avian perceivable colour space. The concentrations of the two known tetrapyrrole eggshell pigments (protoporphyrin and biliverdin) are generally poor predictors of colour, both intra- and interspecifically. Here, we show that the constrained diversity of eggshell coloration can be accurately predicted by colour mixing models based on the relative contribution of both pigments and we demonstrate that the models' predictions can be improved by accounting for the reflectance of the eggshell's calcium carbonate matrix. The establishment of these proximate links between pigmentation and colour will enable future tests of hypotheses on the functions of perceived avian eggshell colours that depend on eggshell chemistry. More generally, colour mixing models are not limited to avian eggshell colours but apply to any natural colour. Our approach illustrates how modelling can aid the understanding of constraints on phenotypic diversity. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. CVB: the Constrained Vapor Bubble Capillary Experiment on the International Space Station MARANGONI FLOW REGION

    Science.gov (United States)

    Wayner, Peter C., Jr.; Kundan, Akshay; Plawsky, Joel

    2014-01-01

    The Constrained Vapor Bubble (CVB) is a wickless, grooved heat pipe and we report on a full- scale fluids experiment flown on the International Space Station (ISS). The CVB system consists of a relatively simple setup a quartz cuvette with sharp corners partially filled with either pentane or an ideal mixture of pentane and isohexane as the working fluids. Along with temperature and pressure measurements, the two-dimensional thickness profile of the menisci formed at the corners of the quartz cuvette was determined using the Light Microscopy Module (LMM). Even with the large, millimeter dimensions of the CVB, interfacial forces dominate in these exceedingly small Bond Number systems. The experiments were carried out at various power inputs. Although conceptually simple, the transport processes were found to be very complex with many different regions. At the heated end of the CVB, due to a high temperature gradient, we observed Marangoni flow at some power inputs. This region from the heated end to the central drop region is defined as a Marangoni dominated region. We present a simple analysis based on interfacial phenomena using only measurements from the ISS experiments that lead to a predictive equation for the thickness of the film near the heated end of the CVB. The average pressure gradient for flow in the film is assumed due to the measured capillary pressure at the two ends of the liquid film and that the pressure stress gradient due to cohesion self adjusts to a constant value over a distance L. The boundary conditions are the no slip condition at the wall interface and an interfacial shear stress at the liquid- vapor interface due to the Marangoni stress, which is due to the high temperature gradient. Although the heated end is extremely complex, since it includes three- dimensional variations in radiation, conduction, evaporation, condensation, fluid flow and interfacial forces, we find that using the above simplifying assumptions, a simple successful

  4. Pressure-constrained, reduced-DOF, interconnected parallel manipulators with applications to space suit design

    Science.gov (United States)

    Jacobs, Shane Earl

    This dissertation presents the concept of a Morphing Upper Torso, an innovative pressure suit design that incorporates robotic elements to enable a resizable, highly mobile and easy to don/doff spacesuit. The torso is modeled as a system of interconnected, pressure-constrained, reduced-DOF, wire-actuated parallel manipulators, that enable the dimensions of the suit to be reconfigured to match the wearer. The kinematics, dynamics and control of wire-actuated manipulators are derived and simulated, along with the Jacobian transforms, which relate the total twist vector of the system to the vector of actuator velocities. Tools are developed that allow calculation of the workspace for both single and interconnected reduced-DOF robots of this type, using knowledge of the link lengths. The forward kinematics and statics equations are combined and solved to produce the pose of the platforms along with the link tensions. These tools allow analysis of the full Morphing Upper Torso design, in which the back hatch of a rear-entry torso is interconnected with the waist ring, helmet ring and two scye bearings. Half-scale and full-scale experimental models are used along with analytical models to examine the feasibility of this novel space suit concept. The analytical and experimental results demonstrate that the torso could be expanded to facilitate donning and doffng, and then contracted to match different wearer's body dimensions. Using the system of interconnected parallel manipulators, suit components can be accurately repositioned to different desired configurations. The demonstrated feasibility of the Morphing Upper Torso concept makes it an exciting candidate for inclusion in a future planetary suit architecture.

  5. 3D Path Planning for Autonomous Aerial Vehicles in Constrained Spaces

    DEFF Research Database (Denmark)

    Schøler, Flemming

    , this planner uses a more analytical approach since it relies on combinations of optimal curves. Both planners operate on an explicit description of the configuration space in a work space containing 3D obstacles. A method was developed that generates convex configuration space obstacles from any point clouds...

  6. Preparation and Application of MnO2 Nanoparticles/Zeolite AgY Composite Catalyst by Confined Space Synthesis (CSS Method for the Desulfurization and Elimination of SP and OPP

    Directory of Open Access Journals (Sweden)

    M. Sadeghi

    2012-12-01

    Full Text Available In this work, zeolite NaY was prepared by hydrothermal method. Then, silver ions were replaced in the zeolite NaY with silver nitrate (AgNO3 solution via using ion exchange (IE method. The Manganese dioxide (MnO2 nanoparticles (9.3 and 15.8 wt % for guest were deposited in the zeolite AgY(host structure with Mn(NO32 aqueous and KMnO4 solutions by confined space synthesis (CSS method. Synthesized samples were studied and characterized via XRD, SEM/EDAX, FTIR, AAS and N2-BET techniques. The desulfurization  and  elimination  reaction of 2- chloroethyl phenyl sulfide (2-CEPS and DEPPT (O, S-diethyl phenyl phosphonothioate have been investigated by 15.8 wt% Nano MnO2/Zeolite AgY composite and MnO2  nanoparticles catalysts and via GC, GC-MS and 31 PNMR.

  7. Managing space-time networks for the dynamic time-constrained VRP

    OpenAIRE

    ZEDDINI, Besma; ZARGAYOUNA, Mahdi; YASSINE, Adnan; TEMANI, Moncef

    2012-01-01

    Vehicle routing problems are highly complex problems for which different artificial intelligence techniques have been used. In this paper, we propose an agent-oriented self-organization model for the dynamic version of the problem with time windows. Our proposal is based on a space-time representation of teh agent's Action Zones, which is able to maintain a good distribution of the vehicles on the environment. This distribution answers the objective of the dynamic problem, since it allows the...

  8. Templating mesoporous zeolites

    DEFF Research Database (Denmark)

    Egeblad, Kresten; Christensen, Christina Hviid; Kustova, Marina

    2008-01-01

    The application of templating methods to produce zeolite materials with hierarchical bi- or trimodal pore size distributions is reviewed with emphasis on mesoporous materials. Hierarchical zeolite materials are categorized into three distinctly different types of materials: hierarchical zeolite...... originates almost exclusively from the support material. The methods for introducing mesopores into zeolite materials are discussed and categorized. In general, mesopores can be templated in zeolite materials by use of solid templating, supramolecular templating, or indirect templating....... In this categorization of templating methods, the nature of the interface between the zeolite crystal and the mesopore exactly when the mesopore starts to form is emphasized. In solid templating, the zeolite crystal is in intimate contact with a solid material that is being removed to produce the mesoporosity. Similarly...

  9. The phase-space structure of nearby dark matter as constrained by the SDSS

    Science.gov (United States)

    Leclercq, Florent; Jasche, Jens; Lavaux, Guilhem; Wandelt, Benjamin; Percival, Will

    2017-06-01

    Previous studies using numerical simulations have demonstrated that the shape of the cosmic web can be described by studying the Lagrangian displacement field. We extend these analyses, showing that it is now possible to perform a Lagrangian description of cosmic structure in the nearby Universe based on large-scale structure observations. Building upon recent Bayesian large-scale inference of initial conditions, we present a cosmographic analysis of the dark matter distribution and its evolution, referred to as the dark matter phase-space sheet, in the nearby universe as probed by the Sloan Digital Sky Survey main galaxy sample. We consider its stretchings and foldings using a tetrahedral tessellation of the Lagrangian lattice. The method provides extremely accurate estimates of nearby density and velocity fields, even in regions of low galaxy density. It also measures the number of matter streams, and the deformation and parity reversals of fluid elements, which were previously thought inaccessible using observations. We illustrate the approach by showing the phase-space structure of known objects of the nearby Universe such as the Sloan Great Wall, the Coma cluster and the Boötes void. We dissect cosmic structures into four distinct components (voids, sheets, filaments, and clusters), using the Lagrangian classifiers DIVA, ORIGAMI, and a new scheme which we introduce and call LICH. Because these classifiers use information other than the sheer local density, identified structures explicitly carry physical information about their formation history. Accessing the phase-space structure of dark matter in galaxy surveys opens the way for new confrontations of observational data and theoretical models. We have made our data products publicly available.

  10. The phase-space structure of nearby dark matter as constrained by the SDSS

    International Nuclear Information System (INIS)

    Leclercq, Florent; Percival, Will; Jasche, Jens; Lavaux, Guilhem; Wandelt, Benjamin

    2017-01-01

    Previous studies using numerical simulations have demonstrated that the shape of the cosmic web can be described by studying the Lagrangian displacement field. We extend these analyses, showing that it is now possible to perform a Lagrangian description of cosmic structure in the nearby Universe based on large-scale structure observations. Building upon recent Bayesian large-scale inference of initial conditions, we present a cosmographic analysis of the dark matter distribution and its evolution, referred to as the dark matter phase-space sheet, in the nearby universe as probed by the Sloan Digital Sky Survey main galaxy sample. We consider its stretchings and foldings using a tetrahedral tessellation of the Lagrangian lattice. The method provides extremely accurate estimates of nearby density and velocity fields, even in regions of low galaxy density. It also measures the number of matter streams, and the deformation and parity reversals of fluid elements, which were previously thought inaccessible using observations. We illustrate the approach by showing the phase-space structure of known objects of the nearby Universe such as the Sloan Great Wall, the Coma cluster and the Boötes void. We dissect cosmic structures into four distinct components (voids, sheets, filaments, and clusters), using the Lagrangian classifiers DIVA, ORIGAMI, and a new scheme which we introduce and call LICH. Because these classifiers use information other than the sheer local density, identified structures explicitly carry physical information about their formation history. Accessing the phase-space structure of dark matter in galaxy surveys opens the way for new confrontations of observational data and theoretical models. We have made our data products publicly available.

  11. Exploring the data constrained phase space of the last Antarctic glacial cycle

    Science.gov (United States)

    Lecavalier, Benoit; Tarasov, Lev

    2017-04-01

    The evolution of the Antarctic Ice Sheet over the last two glacial cycles is studied using the Glacial Systems Model (GSM). Glaciological modelling is an effective tool to generate continental-scale reconstructions over glacial cycles, but the models depend on parameterizations to account for the deficiencies (e.g., missing physics, unresolved sub-grid processes, uncertain boundary conditions) inherent in any numerical model. These parameters, considered together, form a parameter phase space from which sets of parameters can be sampled; each set corresponds to an ice sheet reconstruction. The GSM has been updated with a number of recent developments: hybrid SIA-SSA physics, Schoof grounding line parameterization, broadened degrees of freedom in the climate forcing, sub-shelf melt explicitly dependent on ocean temperatures, improved hydrofracturing, cliff failure at the margins, basal topographic uncertainties, impact of basal drag roughness and subgrid statistics, and first order geoidal corrections in the coupled glacial isostatic adjustment component. Parametric uncertainties are defined in the GSM using >36 ensemble parameters. Prior to conducting a full Bayesian calibration, one must first validate the ability of the GSM to simulate a broad range of responses. We attempt this by latin hypercube sampling of the parameter phase space and comparing the model predictions against our constraint database consisting of past elevation, extent and relative sea level observations and the present day geometry. We document the capability of the GSM to envelope the observational constraints given the parametric uncertainties and discuss the implications for the evolution of the Antarctic Ice Sheet.

  12. On the origin of power-law distributions in systems with constrained phase space

    Directory of Open Access Journals (Sweden)

    E.V. Vakarin

    2013-01-01

    Full Text Available Behavior of condensed matter systems deviating from the standard equilibrium conditions is discussed. Statistical properties of coupled dynamic-stochastic systems are studied within a combination of the maximum information principle and the superstatistical approach. The conditions at which the Shannon entropy functional leads to a power-law statistics are investigated. It is demonstrated that, from a quite general point of view, the power-law dependencies may appear as a consequence of "global" constraints restricting both the dynamic phase space and the stochastic fluctuations. As a result, at sufficiently long observation times the dynamic counterpart is driven into a non-equilibrium steady state whose deviation from the usual exponential statistics is given by the distance from the conventional equilibrium.

  13. Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

    International Nuclear Information System (INIS)

    Fletcher, Rachel E.; Wells, Stephen A.; Leung, Ka Ming; Edwards, Peter P.; Sartbaeva, Asel

    2015-01-01

    Framework materials possess intrinsic flexibility which can be investigated using geometric simulation. We review framework flexibility properties in energy materials and present novel results on the flexibility window of the EMT zeolite framework containing 18-crown-6 ether as a structure directing agent (SDA). Framework materials have structures containing strongly bonded polyhedral groups of atoms connected through their vertices. Typically the energy cost for variations of the inter-polyhedral geometry is much less than the cost of distortions of the polyhedra themselves – as in the case of silicates, where the geometry of the SiO 4 tetrahedral group is much more strongly constrained than the Si—O—Si bridging angle. As a result, framework materials frequently display intrinsic flexibility, and their dynamic and static properties are strongly influenced by low-energy collective motions of the polyhedra. Insight into these motions can be obtained in reciprocal space through the ‘rigid unit mode’ (RUM) model, and in real-space through template-based geometric simulations. We briefly review the framework flexibility phenomena in energy-relevant materials, including ionic conductors, perovskites and zeolites. In particular we examine the ‘flexibility window’ phenomenon in zeolites and present novel results on the flexibility window of the EMT framework, which shed light on the role of structure-directing agents. Our key finding is that the crown ether, despite its steric bulk, does not limit the geometric flexibility of the framework

  14. Synthesis strategies in the search for hierarchical zeolites.

    Science.gov (United States)

    Serrano, D P; Escola, J M; Pizarro, P

    2013-05-07

    Great interest has arisen in the past years in the development of hierarchical zeolites, having at least two levels of porosities. Hierarchical zeolites show an enhanced accessibility, leading to improved catalytic activity in reactions suffering from steric and/or diffusional limitations. Moreover, the secondary porosity offers an ideal space for the deposition of additional active phases and for functionalization with organic moieties. However, the secondary surface represents a discontinuity of the crystalline framework, with a low connectivity and a high concentration of silanols. Consequently, hierarchical zeolites exhibit a less "zeolitic behaviour" than conventional ones in terms of acidity, hydrophobic/hydrophilic character, confinement effects, shape-selectivity and hydrothermal stability. Nevertheless, this secondary surface is far from being amorphous, which provides hierarchical zeolites with a set of novel features. A wide variety of innovative strategies have been developed for generating a secondary porosity in zeolites. In the present review, the different synthetic routes leading to hierarchical zeolites have been classified into five categories: removal of framework atoms, surfactant-assisted procedures, hard-templating, zeolitization of preformed solids and organosilane-based methods. Significant advances have been achieved recently in several of these alternatives. These include desilication, due to its versatility, dual templating with polyquaternary ammonium surfactants and framework reorganization by treatment with surfactant-containing basic solutions. In the last two cases, the materials so prepared show both mesoscopic ordering and zeolitic lattice planes. Likewise, interesting results have been obtained with the incorporation of different types of organosilanes into the zeolite crystallization gels, taking advantage of their high affinity for silicate and aluminosilicate species. Crystallization of organofunctionalized species favours the

  15. Functional design space of single-veined leaves: role of tissue hydraulic properties in constraining leaf size and shape.

    Science.gov (United States)

    Zwieniecki, Maciej A; Boyce, C Kevin; Holbrook, N Michele

    2004-10-01

    Morphological diversity of leaves is usually quantified with geometrical characters, while in many cases a simple set of biophysical parameters are involved in constraining size and shape. One of the main physiological functions of the leaf is transpiration and thus one can expect that leaf hydraulic parameters can be used to predict potential morphologies, although with the caveat that morphology in turn influences physiological parameters including light interception and boundary layer thickness and thereby heat transfer and net photosynthesis. An iterative model was used to determine the relative sizes and shapes that are functionally possible for single-veined leaves as defined by their ability to supply the entire leaf lamina with sufficient water to prevent stomatal closure. The model variables include the hydraulic resistances associated with vein axial and radial transport, as well as with water movement through the mesophyll and the leaf surface. The four parameters included in the model are sufficient to define a hydraulic functional design space that includes all single-veined leaf shapes found in nature, including scale-, awl- and needle-like morphologies. This exercise demonstrates that hydraulic parameters have dissimilar effects: surface resistance primarily affects leaf size, while radial and mesophyll resistances primarily affect leaf shape. These distinctions between hydraulic parameters, as well as the differential accessibility of different morphologies, might relate to the convergent evolutionary patterns seen in a variety of fossil lineages concerning overall morphology and anatomical detail that frequently have evolved in linear and simple multi-veined leaves.

  16. Catalysis with hierarchical zeolites

    DEFF Research Database (Denmark)

    Holm, Martin Spangsberg; Taarning, Esben; Egeblad, Kresten

    2011-01-01

    zeolites that have been reported hitherto. Prototypical examples from some of the different categories of catalytic reactions that have been studied using hierarchical zeolite catalysts are highlighted. This clearly illustrates the different ways that improved performance can be achieved with this family...

  17. Flexibility of zeolite frameworks

    Science.gov (United States)

    Kapko, Vitaliy; Treacy, Michael; Thorpe, Michael

    2009-03-01

    Zeolites are an important class of industrial catalysts because of their large internal surfaces and molecular-sieving properties. Recent geometric simulations (1) show that almost all of the known zeolites can exist without distortion of their tetrahedra within some range of densities, which we call the flexibility window. Within this window, the framework accommodates density changes by rotations about the shared tetrahedral corners. We argue that the presence of a flexibility window can be used as a topological criterion to select potential candidates for synthesis from millions of hypothetical structures. We also investigate the exceptions to the rule, as well as the shape of the flexibility window and the symmetric properties of zeolites inside it. (1) A. Sartbaeva, S.A. Wells, M.M.J. Treacy and M.F. Thorpe The flexibility window in zeolites, Nature Materials 5, 962-965 (2006); I. Rivin, commentary 931-932.

  18. Robust Constrained Optimization Approach to Control Design for International Space Station Centrifuge Rotor Auto Balancing Control System

    National Research Council Canada - National Science Library

    Postma, Barry D

    2005-01-01

    .... The robustness constraints are posed with respect to parametric uncertainty in the plant. The proposed approach to control design allows for both of these objectives to be handled within the framework of constrained optimization. The resulting controller achieves acceptable performance and robustness characteristics.

  19. Preparation of functionalized zeolitic frameworks

    Science.gov (United States)

    Yaghi, Omar M; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P

    2012-11-20

    The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

  20. Preparation of functionalized zeolitic frameworks

    Science.gov (United States)

    Yaghi, Omar M; Furukawa, Hiroyasu; Wang, Bo

    2013-07-09

    The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

  1. Cooling design and evaluation for photovoltaic cells within constrained space in a CPV/CSP hybrid solar system

    International Nuclear Information System (INIS)

    Wang, Sheng; Shi, Junxiang; Chen, Hsiu-Hung; Schafer, Steven R.; Munir, Moiz; Stecker, Greg; Pan, Wei; Lee, Jong-Jan; Chen, Chung-Lung

    2017-01-01

    Highlights: • A practical cooling solution is proposed for a novel CPV/CSP hybrid solar system. • Both passive and active cooling techniques were systematically investigated. • Comprehensive experimental and numerical studies were conducted for optimal design. • Active cooling is in great need for a high waste heat flux of 21.8 W/cm 2 . • Passive cooling becomes attractive for a waste heat flux less than 13.0 W/cm 2 . - Abstract: A hybrid solar energy system has been designed by combining the advantages of concentrated solar power (CSP) technology and high performance concentrated photovoltaic (CPV) cells which outperforms either single technology. Thermal management is crucial to CPV cells in this hybrid solar system, as concentrated solar radiation onto the PV cells leads to higher heat flux. If the heat is not dissipated effectively, it can cause obvious temperature rise and efficiency reduction in the cell. In addition, the constrained space available for PV cell cooling in such hybrid solar systems presents more challenges. In this study both passive cooling and active cooling techniques were systematically investigated in both numerical and experimental ways. For the passive cooling method, two different designs from off-the-shelf heat pipes with radial fins or annular fins were proposed and studied under various heat rejection requirements. Results shows that heat pipes with radial fins exhibited narrow capability of dumping the heat, while heat pipes with annular fins presented better performances under the same conditions. Numerical optimal designs of annular fin numbers and fin gaps were then carried out and experimentally validated, indicating a capability of dumping moderate waste heat (∼45 W). For active cooling technique, a comprehensive study of designing plate fin heatsinks were conducted corresponding to high Ingress Protection (IP) rated off-the-shelf fans. Results show that with a less than 2 W fan power consumption, this active

  2. Rapid synthesis of beta zeolites

    Science.gov (United States)

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

    2015-08-18

    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  3. for zeolite coating

    Directory of Open Access Journals (Sweden)

    Carlos Renato Rambo

    2006-01-01

    Full Text Available Biotemplating is the processing of microcellular ceramics by reproduction of natural morphologies, where the microstructural features of the biotemplate are maintained in the biomorphic ceramic. Different biotemplates with distinct pore anatomies were used to produce biomorphic supports for the zeolite coating: wood, cardboard, sea-sponge and sisal. The biomorphic ceramics were produced by distinguished processing routes: Al-gas infiltration-reaction, liquid-metal infiltration, dip-coating and sol-gel synthesis, in order to produce nitrides, carbides and oxides, depending on the processing conditions. The zeolite coating was performed by hydrothermal growth of MFI-type (Silicalite-1 and ZSM-5 zeolite crystals onto the internal pore walls of the biomorphic templates. The final biomorphic ceramic-zeolite composites were physically characterized, evaluated in terms of their gas adsorption capabilities and correlated to their microstructure and specific pore anatomy. The combination of the properties of the biomorphic ceramics with the adsorption properties of zeolites results in materials with distinct properties as potential candidates for adsorption and catalytic applications due to their characteristic porosity, molecular sieving capabilities and high thermo-mechanical strength.

  4. Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework.

    Science.gov (United States)

    Fletcher, Rachel E; Wells, Stephen A; Leung, Ka Ming; Edwards, Peter P; Sartbaeva, Asel

    2015-12-01

    Framework materials have structures containing strongly bonded polyhedral groups of atoms connected through their vertices. Typically the energy cost for variations of the inter-polyhedral geometry is much less than the cost of distortions of the polyhedra themselves - as in the case of silicates, where the geometry of the SiO4 tetrahedral group is much more strongly constrained than the Si-O-Si bridging angle. As a result, framework materials frequently display intrinsic flexibility, and their dynamic and static properties are strongly influenced by low-energy collective motions of the polyhedra. Insight into these motions can be obtained in reciprocal space through the `rigid unit mode' (RUM) model, and in real-space through template-based geometric simulations. We briefly review the framework flexibility phenomena in energy-relevant materials, including ionic conductors, perovskites and zeolites. In particular we examine the `flexibility window' phenomenon in zeolites and present novel results on the flexibility window of the EMT framework, which shed light on the role of structure-directing agents. Our key finding is that the crown ether, despite its steric bulk, does not limit the geometric flexibility of the framework.

  5. Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

    Directory of Open Access Journals (Sweden)

    Prabir K. Dutta

    2012-04-01

    Full Text Available The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors.

  6. Powder Diffraction in Zeolite Science

    Science.gov (United States)

    Burton, Allen W.

    This tutorial discusses the fundamental principles of X-ray diffraction and its applications in zeolite science. The early sections review the physics of diffraction, crystal symmetry, and reciprocal space. We discuss how the intensity of diffracted radiation is affected both by geometric effects involving detection (the Lorentz-polarization factor) and by the arrangement of atoms within the crystal (the structure factor). The differences between powder diffraction and single-crystal diffraction are then described, and differences between X-ray and neutron diffraction are also discussed. Later sections describe the effects of symmetry, lattice substitution, crystallite size, residual strain, preferred orientation, and X-ray absorption. Special emphasis is placed on the proper application of the Scherrer analysis in reporting crystalize size. The principles of structure solution from direct methods and Patterson methods are then introduced, and a description of Rietveld analysis is given. Finally the effects of stacking disorder on a powder diffraction pattern are presented.

  7. Methane emissions abatement by multi-ion-exchanged zeolite A prepared from both commercial-grade zeolite and coal fly ash.

    Science.gov (United States)

    Hui, K S; Chao, C Y H

    2008-10-01

    The performance of multimetal-(Cu, Cr, Zn, Ni, and Co)-ion-exchanged zeolite A prepared from both a commercial-grade sample and one produced from coal fly ash in methane emissions abatement was evaluated in this study. The ion-exchange process was used to load the metal ions in zeolite A samples. The methane conversion efficiency by the samples was studied under various parameters including the amount of metal loading (7.3-19.4 wt%), reaction temperature (25-500 degrees C), space velocity (8400-41 900 h(-1)), and methane concentration (0.5-3.2 vol %). At 500 degrees C, the original commercial-grade zeolite A catalyzed 3% of the methane only, whereas the addition of different percentages of metals in the sample enhanced the methane conversion efficiency by 40-85%. Greater methane conversion was observed by increasing the percentage of metals added to the zeolite even though the BET surface area of the zeolite consequently decreased. Higher percentage methane conversion over the multi-ion-exchanged samples was observed at lower space velocities indicating the importance of the mass diffusion of reactants and products in the zeolite. Compared to the multi-ion-exchanged zeolite A prepared from the commercial-grade zeolite, the one produced from coal fly ash demonstrated similar performances in methane emissions abatement, showing the potential use of this low cost recycled material in gaseous pollutant treatment.

  8. Catalytic transformation of methyl benzenes over zeolite catalysts

    KAUST Repository

    Al-Khattaf, S.

    2011-02-01

    Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4-trimethyl benzene) has been investigated over ZSM-5, TNU-9, mordenite and SSZ-33 catalysts in a novel riser simulator at different operating conditions. Catalytic experiments were carried out in the temperature range of 300-400 °C to understand the transformation of these alkyl benzenes over large pore (mordenite and SSZ-33) in contrast to medium-pore (ZSM-5 and TNU-9) zeolite-based catalysts. The effect of reaction conditions on the isomerization to disproportionation product ratio, distribution of trimethylbenzene (TMB) isomers, and p-xylene/o-xylene ratios are reported. The sequence of reactivity of the three alkyl benzenes depends upon the pore structure of zeolites. The zeolite structure controls primarily the diffusion of reactants and products while the acidity of these zeolites is of a secondary importance. In the case of medium pore zeolites, the order of conversion was m-xylene > 1,2,4-TMB > toluene. Over large pore zeolites the order of reactivity was 1,2,4-TMB > m-xylene > toluene for SSZ-33 catalyst, and m-xylene ∼ 1,2,4-TMB > toluene over mordenite. Significant effect of pore size between ZSM-5 and TNU-9 was observed; although TNU-9 is also 3D 10-ring channel system, its slightly larger pores compared with ZSM-5 provide sufficient reaction space to behave like large-pore zeolites in transformation of aromatic hydrocarbons. We have also carried out kinetic studies for these reactions and activation energies for all three reactants over all zeolite catalysts under study have been calculated. © 2011 Elsevier B.V.

  9. Zeolites and clays behavior in presence of radioactive solutions

    International Nuclear Information System (INIS)

    Carrera Garcia, L.M.

    1991-01-01

    Natural aluminosilicates have found application as selective ion exchangers for radioactive cations, present in liquid wastes arising from nuclear facilities. Among severals cations and complex mixtures of them, Co is a common constituent of liquid radioactive wastes. Two types of zeolites (Y zeolite, and natural mexican erionite), and two types of clays (natural bentonite, and Al-expanded bentonite (Al-B) were used. Previous to the experiments, the zeolites and the natural bentonite were stabilized to their respective Na + form using 5N NaCl solution. 2Na + → 60 Co 2+ ion exchange kinetics in zeolites and clays was followed by gamma spectrometry using a NaCl-Co(NO 3 ) 2 isonormal solution (0.1N) labeled with 60 Co-Co(NO 3 ) 2 (100 μ Ci). Before and after experiments, the structural changes in the cristallinity of aluminosilicates were determined by X-ray diffraction. XRD analyzes show that the cristallinity of the aluminosilicates was not affected by ion exchange. After Co exchange the cell parameters were determined in all samples. The efficiency of zeolites, natual clays and expanded clays to remove cobalt ions from solutions depends on the ion echange capacity of the material. Results for long contacts time, 18 days, show that Co is more effectively removed by Y zeolite ( 4.07 wt %), followed by erionite (3.09 wt %), then bentonite ( 2.36 wt %) and finally expanded bentonite ( 0.70 wt %). In Y zeolite an unusual fast soportion uptake of 4.51 % wt Co was observed followed by a desorption process to 4.07 %. This effect is due to the different hydration degree of zeolites during the contact time between the zeolite and the 60 Co solution. In erionite the exchange is lower than in Y-zeolite, frist because the Si/Al ratio is higher for erionite than for Y-zeolite and second because K ions in erionite cannot be exchanged during the stabilization of erionite in 5N NaCl solution. The low exchange in expanded bentonite was expected because its cation exchange

  10. CONSTRAINING THE MILKY WAY POTENTIAL WITH A SIX-DIMENSIONAL PHASE-SPACE MAP OF THE GD-1 STELLAR STREAM

    International Nuclear Information System (INIS)

    Koposov, Sergey E.; Rix, Hans-Walter; Hogg, David W.

    2010-01-01

    The narrow GD-1 stream of stars, spanning 60 0 on the sky at a distance of ∼10 kpc from the Sun and ∼15 kpc from the Galactic center, is presumed to be debris from a tidally disrupted star cluster that traces out a test-particle orbit in the Milky Way halo. We combine Sloan Digital Sky Survey (SDSS) photometry, USNO-B astrometry, and SDSS and Calar Alto spectroscopy to construct a complete, empirical six-dimensional (6D) phase-space map of the stream. We find that an eccentric orbit in a flattened isothermal potential describes this phase-space map well. Even after marginalizing over the stream orbital parameters and the distance from the Sun to the Galactic center, the orbital fit to GD-1 places strong constraints on the circular velocity at the Sun's radius V c = 224 ± 13 km s -1 and total potential flattening q Φ = 0.87 +0.07 -0.04 . When we drop any informative priors on V c , the GD-1 constraint becomes V c = 221 ± 18 km s -1 . Our 6D map of GD-1, therefore, yields the best current constraint on V c and the only strong constraint on q Φ at Galactocentric radii near R ∼ 15 kpc. Much, if not all, of the total potential flattening may be attributed to the mass in the stellar disk, so the GD-1 constraints on the flattening of the halo itself are weak: q Φ,halo > 0.89 at 90% confidence. The greatest uncertainty in the 6D map and the orbital analysis stems from the photometric distances, which will be obviated by GAIA.

  11. Thermal behavior of natural zeolites

    International Nuclear Information System (INIS)

    Bish, D.L.

    1993-01-01

    Thermal behavior of natural zeolites impacts their application and identification and varies significantly from zeolite to zeolite. Zeolites evolve H 2 0 upon heating, but recent data show that distinct ''types'' of water (e.g., loosely bound or tightly bound zeolitic water) do not exist. Rather water is bound primarily to extra-framework cations with a continuum of energies, giving rise to pseudocontinuous loss of water accompanied by a dynamic interaction between remaining H 2 0 molecules and extra-framework cations. These interactions in the channels of zeolites give rise to dehydration dependent on the extra-framework cation, in addition to temperature and water vapor pressure. The dehydration reaction and the extra-framework cation also affect the thermal expansion/contraction. Most zeolites undergo dehydration-induced contractions that may be anisotropic, although minor thermal expansion can be seen with some zeolites. Such contractions can be partially or completely irreversible if they involve modifications of the tetrahedral framework and/or if rehydration is sluggish. Thermally induced structural modifications are also driven initially by dehydration and the concomitant contraction and migration of extra-framework cations. Contraction is accommodated by rotations of structural units and tetrahedral cation-oxygen linkages may break. Thermal reactions that involve breaking of tetrahedral cation-oxygen bonds markedly irreversible and may be kinetically limited, producing large differences between short- and long-term heating

  12. Mesoporous zeolites obtained by desilication

    NARCIS (Netherlands)

    Groen, J.C.

    2007-01-01

    Zeolites are crystalline microporous materials consisting of silicon, aluminium and oxygen atoms. A unique combination of properties such as high surface area, high (hydro)thermal stability, and strong acidity, makes that zeolites are frequently used as catalysts in various (petro)chemical

  13. Time- and space-resolved study of the methanol to hydrocarbons (MTH) reaction - influence of zeolite topology on axial deactivation patterns.

    Science.gov (United States)

    Rojo-Gama, Daniel; Etemadi, Samaneh; Kirby, Eliot; Lillerud, Karl Petter; Beato, Pablo; Svelle, Stian; Olsbye, Unni

    2017-04-28

    Zeolites representing seven different topologies were subjected to life-time assessment studies as methanol to hydrocarbons (MTH) catalysts at 400 °C, P(MeOH) = 13 kPa and P(tot) = 100 kPa. The following topologies were studied: ZSM-22 (TON), ZSM-23 (MTT), IM-5 (IMF), ITQ-13 (ITH), ZSM-5 (MFI), mordenite (MOR) and beta (BEA). Two experimental approaches were used. In the first approach, each catalyst was tested at three different contact times, all giving 100% initial conversion. The life-time before conversion decreased to 50% at each contact time was measured and used to calculate critical contact times (i.e. the contact time needed to launch the autocatalytic MTH reaction) and deactivation rates. It was found that the critical contact time is strongly correlated with pore size: the smaller the pore size, the longer the critical contact time. The second experimental approach consisted of testing the catalysts in a double tube reactor with 100% initial conversion, and quenching the reaction after 4 consecutive times on stream, representing full, partial, and zero conversion. After quenching, the catalyst bed was divided into four segments, which were individually characterised for coke content (temperature-programmed oxidation) and specific surface area (N 2 adsorption). The axial deactivation pattern was found to depend on pore size. With increasing pore size, the main source of coke formation changed from methanol conversion (1D 10-ring structures), to partly methanol, partly product conversion (3D 10-ring structures) and finally mainly product conversion (3D 12-ring structure). As a result, the methanol conversion capacity changed little with contact time for ZSM-5, while it increased with increasing contact time for the catalysts with smaller pore sizes, and decreased with increasing contact time for pore sizes larger than ZSM-5.

  14. Method for producing zeolites and zeotypes

    DEFF Research Database (Denmark)

    2015-01-01

    The invention relates to a method for producing zeolite, zeolite-like or zeotype particles comprising the steps of: 1 ) Adding one or more metal precursors to a silica or alumina source; 2) Reducing the one or more metal precursors to form metal nanoparticles on the surface of the silica or alumina...... source; 3) Passing a gaseous hydrocarbon, alkyl alcohol or alkyl ether over the silica or alumina supported metal nanoparticle to form a carbon template coated zeolite, zeolite-like or zeotype precursor composition; 4a) Adding a structure directing agent to the carbon template coated zeolite, zeolite......-like or zeotype precursor composition thereby creating a zeolite, zeolite-like or zeotype gel composition; 4b) Crystallising the zeolite, zeolite-like or zeotype gel composition by subjecting said composition to a hydrothermal treatment; 5) Removing the carbon template and structure directing agent and isolating...

  15. Method of producing zeolite encapsulated nanoparticles

    DEFF Research Database (Denmark)

    2015-01-01

    The invention therefore relates to a method for producing zeolite, zeolite-like or zeotype encapsulated metal nanoparticles, the method comprises the steps of: 1) Adding one or more metal precursors to a silica or alumina source; 2) Reducing the one or more metal precursors to form metal...... nanoparticles on the surface of the silica or alumina source; 3) Passing a gaseous hydrocarbon, alkyl alcohol or alkyl ether over the silica or alumina supported metal nanoparticles to form a carbon template coated zeolite, zeolite-like or zeotype precursor composition; 4a) Adding a structure directing agent...... to the carbon template coated zeolite, zeolite-like or zeotype precursor composition thereby creating a zeolite, zeolite-like or zeotype gel composition; 4b) Crystallising the zeolite, zeolite-like or zeotype gel composition by subjecting said composition to a hydrothermal treatment; 5) Removing the carbon...

  16. INTERKALASI XILENOL ORANGE PADA ZEOLIT ALAM LAMPUNG SEBAGAI ELEKTRODA ZEOLIT TERMODIFIKASI

    Directory of Open Access Journals (Sweden)

    Fitriyah Fitriyah

    2016-07-01

    Full Text Available Zeolit terbagi menjadi zeolit alam dan zeolit sintesis, kapasitas adsorpsi zeolit alam umumnya lebih rendah daripada zeolit sintesis, sehingga untuk meningkatkan kapasitas adsorpsinya, karakter permukaan zeolit alam perlu diubah dengan melakukan proses modifikasi permukaan melalui berbagai metode, salah satunya dengan metode interkalasi. Tujuan penelitian ini yaitu menginterkalasi zat warna xilenol orange ke dalam zeolit alam Lampung dan mengaplikasikannya sebagai elektroda zeolit termodifikasi. Melalui proses interkalasi diharapkan dapat meningkatkan kegunaan dan nilai tambah dari zeolit. Data hasil penelitian menunjukkan bahwa xilenol orange (XO dapat diinterkalasikan ke dalam zeolit, hal ini dapat dilihat dari pita spektrum FTIR yang memiliki serapan pada bilangan gelombang 1383 cm-1, yaitu menunjukkan serapan dari S=O simetris dan asimetris pada gugus –SO3H,hal ini diduga karena XO memiliki gugus SO3 sehingga menyebabkan adanya serangan pada proton zeolit. Berdasarkan penelitian dapat disarikan bahwa xilanol orange dapat terinterkalasi pada zeolit alam Lampung dan dapat dimanfaatkan sebagai elektroda pendeteksi logam.

  17. Effect of hydrophilic defects on water transport in MFI zeolites.

    Science.gov (United States)

    Humplik, Thomas; Raj, Rishi; Maroo, Shalabh C; Laoui, Tahar; Wang, Evelyn N

    2014-06-10

    The subnanometer pore structure of zeolites and other microporous materials has been proposed to act as a molecular sieve for various water separation technologies. However, due to the increased interaction between the solid and water in these nanoconfined spaces, it is unclear which type of interface, be it hydrophilic or hydrophobic, offers an advantageous medium for enhancing transport properties. In this work, we probe the role of hydrophilic defects on the transport of water inside the microporous hydrophobic MFI zeolite pore structure via combined sorption and high-pressure infiltration experiments. While the inclusion of defects was observed to increase the amount of water within the zeolite pore network by up to 7 times at the saturation pressure, the diffusivity of this infiltrated water was lowered by up to 2 orders of magnitude in comparison to that of water within the nearly defect-free hydrophobic MFI zeolite. Subsequently, the permeability of water within the more defective MFI zeolite was an order of magnitude lower than that of the nearly defect-free zeolite. The results from these experiments suggest that the intrinsic hydrophobic pore structure of MFI zeolites can facilitate faster water transport due to the decreased attraction between the water and the defect-free surface. While the strong attraction of water to the defects allows for water to infiltrate the porous network at lower pressures, the results suggest that this strong attraction decreases the mobility of the infiltrated water. The insights gained from this study can be utilized to improve the design of future membranes for water desalination and other separation techniques.

  18. The flexibility window in zeolites.

    Science.gov (United States)

    Sartbaeva, Asel; Wells, Stephen A; Treacy, M M J; Thorpe, M F

    2006-12-01

    Today synthetic zeolites are the most important catalysts in petrochemical refineries because of their high internal surface areas and molecular-sieving properties. There have been considerable efforts to synthesize new zeolites with specific pore geometries, to add to the 167 available at present. Millions of hypothetical structures have been generated on the basis of energy minimization, and there is an ongoing search for criteria capable of predicting new zeolite structures. Here we show, by geometric simulation, that all realizable zeolite framework structures show a flexibility window over a range of densities. We conjecture that this flexibility window is a necessary structural feature that enables zeolite synthesis, and therefore provides a valuable selection criterion when evaluating hypothetical zeolite framework structures as potential synthetic targets. We show that it is a general feature that experimental densities of silica zeolites lie at the low-density edge of this window--as the pores are driven to their maximum volume by Coulomb inflation. This is in contrast to most solids, which have the highest density consistent with the local chemical and geometrical constraints.

  19. Pillared MFI zeolite nanosheets of a single-unit-cell thickness.

    Science.gov (United States)

    Na, Kyungsu; Choi, Minkee; Park, Woojin; Sakamoto, Yasuhiro; Terasaki, Osamu; Ryoo, Ryong

    2010-03-31

    Zeolite MFI nanosheets of 2-nm thickness have been hydrothermally synthesized via cooperative assembly between silica and an organic surfactant, which is functionalized with a diquaternary ammonium group. The zeolite nanosheets have been further assembled into their ordered multilamellar mesostructure through hydrophobic interactions between the surfactant tails located outside the zeolite nanosheet. This assembly process involves successive transformations from an initially hexagonal mesophase to a multilamellar mesophase without crystallinity and then to a lamellar mesophase with a crystalline zeolite framework. The mesopore volume in the interlamellar space could be retained by supporting the zeolite nanosheets with silica pillars, as in pillared clays, even after surfactant removal by calcination. The mesopore diameters could be controlled according to the surfactant tail lengths. Due to the interlamellar structural coherence, the hierarchically mesoporous/microporous zeolite could exhibit small-angle X-ray diffraction peaks up to the fourth-order reflections corresponding to the interlayer distance. In addition, an Ar adsorption analysis and transmission electron microscopic investigation indicated that the pillars were highly likely to be built with an MFI structure. The present approach using a zeolite structure-directing functional group contained in a surfactant would be suitable for the synthesis of other related nanomorphous zeolites in the future.

  20. Zeolitization at uranium ore manifestation

    International Nuclear Information System (INIS)

    Petrosyan, R.V.; Buntikova, A.F.

    1981-01-01

    The process of zeolitization at uranium ore manifestation is studied. A specific type of low-temperature wall endogenous alteration of rocks due to the effect of primary acid solution with low content of carbonic acid is established. Leaching of calcium from enclosing rocks and its deposition in ore-accompanying calcium zeolites is a characteristic feature of wall-metasomatosis. Formation of desmin- calcite-laumontite and quartz-fluoroapatite of vein associations, including ore minerals (uranophane and metaotenite), is genetically connected with calcium metasomatosis. On the basis of the connection of ore minerals with endogeneous process of zeolitization a conclusion can be made on endogenous origin of uranophane and metaotenite [ru

  1. Natural zeolite bitumen cracking

    Energy Technology Data Exchange (ETDEWEB)

    Kuznicki, S.M.; McCaffrey, W.C.; Bian, J.; Wangen, E.; Koenig, A. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2006-07-01

    A study was conducted to demonstrate how low cost heavy oil upgrading in the field could reduce the need for diluents while lowering the cost for pipelining. Low cost field upgrading could also contribute to lowering contaminant levels. The performance of visbreaking processes could be improved by using disposable cracking agents. In turn, the economics of field upgrading of in-situ derived bitumen would be improved. However, in order to be viable, such agents would have to be far less expensive than current commercial cracking catalysts. A platy natural zeolite was selected for modification and testing due to its unique chemical and morphological properties. A catalyst-bearing oil sand was then heat-treated for 1 hour at 400 degrees C in a sealed microreactor. Under these mild cracking conditions, the catalyst-bearing oil sand produced extractable products of much lower viscosity. The products also contained considerably more gas oil and middle distillates than raw oil sand processed under the same conditions as thermal cracking alone. According to model cracking studies using hexadecane, these modified mineral zeolites may be more active cracking agents than undiluted premium commercial FCC catalyst. These materials hold promise for partial upgrading schemes to reduce solvent requirements in the field. tabs., figs.

  2. Constrained Vapor Bubble Experiment

    Science.gov (United States)

    Gokhale, Shripad; Plawsky, Joel; Wayner, Peter C., Jr.; Zheng, Ling; Wang, Ying-Xi

    2002-11-01

    Microgravity experiments on the Constrained Vapor Bubble Heat Exchanger, CVB, are being developed for the International Space Station. In particular, we present results of a precursory experimental and theoretical study of the vertical Constrained Vapor Bubble in the Earth's environment. A novel non-isothermal experimental setup was designed and built to study the transport processes in an ethanol/quartz vertical CVB system. Temperature profiles were measured using an in situ PC (personal computer)-based LabView data acquisition system via thermocouples. Film thickness profiles were measured using interferometry. A theoretical model was developed to predict the curvature profile of the stable film in the evaporator. The concept of the total amount of evaporation, which can be obtained directly by integrating the experimental temperature profile, was introduced. Experimentally measured curvature profiles are in good agreement with modeling results. For microgravity conditions, an analytical expression, which reveals an inherent relation between temperature and curvature profiles, was derived.

  3. Zeolite-zeolite composite composed of Y zeolite and single-crystal-like ZSM-5 zeolite: Fabricated by a process like “big fish swallowing little one”

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Meng; Li, Peng [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Zheng, Jiajun, E-mail: zhengjiajun@tyut.edu.cn [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Yujian [SINOPEC Research Institute of Petroleum Processing, Beijing, 100083 (China); Kong, Qinglan [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Tian, Huiping [SINOPEC Research Institute of Petroleum Processing, Beijing, 100083 (China); Li, Ruifeng, E-mail: rfli@tyut.edu.cn [Research Centre of Energy Chemical & Catalytic Technology, Taiyuan University of Technology, Taiyuan 030024 (China)

    2017-06-15

    Zeolite-zeolite composite composed of Y and ZSM-5 zeolite was prepared using depolymerized Y as partial nutrients for the growth of ZSM-5. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), FT-IR, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), N{sub 2} adsorption-desorption measurement and Thermogravimetric analysis (TG). Chemical equilibrium at the solution-crystal interface was changed because of the partially depolymerized Y zeolite, the conditions necessary for the growth of ZSM-5 were therefore obtained. ZSM-5 zeolite crystals nucleated and grew on the interface, and Y zeolite crystals were then gradually swallowed by the growing single-crystal-like ZSM-5. - Graphical abstract: Y zeolite crystals in the hydrothermal system were partially depolymerized and an ambience in favor of the formation of ZSM-5 was formed, and ZSM-5 zeolite crystals nucleated and grew up on the external surfaces of Y zeolite crystals. As a consequence, Y zeolite crystals were swallowed by single-crystal-like ZSM-5. - Highlights: • Zeolite composite is composed by Y zeolite and single-crystal-like ZSM-5. • A composite material formed by a process like “big fish swallowing little one”. • Ratio of two zeolites in the as-synthesized sample can be adjusted.

  4. Preliminary market analysis for large zeolite crystals. B.S. Thesis

    Science.gov (United States)

    Doblmaier, Thomas; Grafing, Paul; Knight, Kim

    1987-01-01

    Zeolite crystals are used in the manufacture of countless products today, which utilize their properties of absorption, ion exchange, and catalysis. It was determined that zeolites grown in space could be much larger in size than any of those currently available on Earth. The objective was to identify and examine some of the potential uses for these larger crystals. Of the several industries examined, the medical and nuclear industries offer the greatest potential.

  5. Metal immobilization in soils using synthetic zeolites

    NARCIS (Netherlands)

    Osté, L.A.; Lexmond, T.M.; Riemsdijk, van W.H.

    2002-01-01

    In situ immobilization of heavy metals in contaminated soils is a technique to improve soil quality. Synthetic zeolites are potentially useful additives to bind heavy metals. This study selected the most effective zeolite in cadmium and zinc binding out of six synthetic zeolites (mordenite-type,

  6. Zeolite from fly ash: synthesis and characterization

    Indian Academy of Sciences (India)

    ... area of the product was found to be 383 m2/g with high purity. The crystallinity of the prepared zeolite was found to change with fusion temperature and a maximum value was obtained at 823 K. The cost of synthesized zeolite was estimated to be almost one-fifth of that of commercial 13X zeolite available in the market.

  7. Response of Wheat Physiological and Agronomic Traits to Water Stress and Zeolite Application

    Directory of Open Access Journals (Sweden)

    M Mirzakhani

    2015-07-01

    Full Text Available With increasing water deficit in agricultural production, quantity and quality of these products will be affected. In order to evaluate the response of wheat physiological and agronomic characteristics to water stress and zeolite application, this study was carried out in field of Arak Payam Noor University in 2009. A split-plot arrangement of treatments in a randomized complete block design with three replications was used. Water stress (I0= Control irrigation, I1= Irrigation about 85% plant requirement water, I2= Irrigation about 70% of plant requirement water, I3= Irrigation about 55% of plant requirement water, were assigned in the main plots and different levels of zeolite application (Z0= without zeolite application, Z1= 3 ton ha-1, Z2= 6 ton ha-1, Z3= 9 ton ha-1 in sub plots. Each sub plot consisted of 4 rows, 5 m long with 50 cm between rows space and 5 cm between plants on the rows. Results indicated that un-stress irrigation (control irrigation with average spike biological yield (36.51 g per 10 plant and zeolite application (9 ton ha-1 with average (34.02 g per 10 plant were significantly superior to the other treatments. The maximum and minimum of grain yield obtained of treatments (control irrigation + 9 ton ha-1 of zeolite and (irrigation about 55% of plant requirement water + 3 ton ha-1 of zeolite, respectively. Zeolite application was positive affected on almost of agronomic and physiologic traits in wheat.

  8. Characterization of Mexican zeolite minerals

    International Nuclear Information System (INIS)

    Jimenez C, M.J.

    2005-01-01

    50% of the Mexican territory is formed by volcanic sequences of the Pliocene type, which appear extensively in the northwest states (Sonora, Sinaloa, Chihuahua, Durango) and west of Mexico (Jalisco and Nayarit), in central Mexico (Zacatecas, Guanajuato, San Luis Potosi, Queretaro, Hidalgo) and south of Mexico (Guerrero, Oaxaca); therefore, it is to be expected that in our country big locations of natural zeolites exist in its majority of the clinoptilolite type. The present study was focused toward the characterization of two Mexican natural zeolite rocks presumably of the clinoptilolite and filipsite types, one of them comes from the state of Chihuahua and the other of a trader company of non metallic minerals, due that these materials are not characterized, its are not known their properties completely and therefore, the uses that can be given to these materials. In this investigation work it was carried out the characterization of two Mexican zeolite rocks, one coming from the Arroyo zone, municipality of La Haciendita, in the state of Chihuahua; and the other one was bought to a trader company of non metallic minerals. The two zeolites so much in their natural form as conditioned with sodium; they were characterized by means of X-ray diffraction, scanning electron microscopy of high vacuum and elementary microanalysis (EDS), surface area analysis (BET), thermal gravimetric analysis. To differentiate the heulandite crystalline phase of the other clinoptilolite rock, its were carried out thermal treatments. The quantification of Al, Na, Ca, K, Mg, Fe was carried out in solution, by means of atomic absorption spectroscopy and the quantity of Si was determined by gravimetry. The zeolite rocks presented for the major part the crystalline heulandite and clinoptilolite phases for the most part, and it was found that the zeolite coming from the state of Chihuahua possesses a bigger content of heulandite and the denominated filipsite it is really a zeolite

  9. Hydrogen storage in Chabazite zeolite frameworks.

    Science.gov (United States)

    Regli, Laura; Zecchina, Adriano; Vitillo, Jenny G; Cocina, Donato; Spoto, Giuseppe; Lamberti, Carlo; Lillerud, Karl P; Olsbye, Unni; Bordiga, Silvia

    2005-09-07

    We have recently highlighted that H-SSZ-13, a highly siliceous zeolite (Si/Al = 11.6) with a chabazitic framework, is the most efficient zeolitic material for hydrogen storage [A. Zecchina, S. Bordiga, J. G. Vitillo, G. Ricchiardi, C. Lamberti, G. Spoto, M. Bjørgen and K. P. Lillerud, J. Am. Chem. Soc., 2005, 127, 6361]. The aim of this new study is thus to clarify both the role played by the acidic strength and by the density of the polarizing centers hosted in the same framework topology in the increase of the adsorptive capabilities of the chabazitic materials towards H2. To achieve this goal, the volumetric experiments of H2 uptake (performed at 77 K) and the transmission IR experiment of H2 adsorption at 15 K have been performed on H-SSZ-13, H-SAPO-34 (the isostructural silico-aluminophosphate material with the same Brønsted site density) and H-CHA (the standard chabazite zeolite: Si/Al = 2.1) materials. We have found that a H2 uptake improvement has been obtained by increasing the acidic strength of the Brønsted sites (moving from H-SAPO-34 to H-SSZ-13). Conversely, the important increase of the Brønsted sites density (moving from H-SSZ-13 to H-CHA) has played a negative role. This unexpected behavior has been explained as follows. The additional Brønsted sites are in mutual interaction via H-bonds inside the small cages of the chabazitic framework and for most of them the energetic cost needed to displace the adjacent OH ligand is higher than the adsorption enthalpy of the OH...H2 adduct. From our work it can be concluded that proton exchanged chabazitic frameworks represent, among zeolites, the most efficient materials for hydrogen storage. We have shown that a proper balance between available space (volume accessible to hydrogen), high contact surface, and specific interaction with strong and isolated polarizing centers are the necessary characteristics requested to design better materials for molecular H2 storage.

  10. Surface photochemistry: alloxazine within nanochannels of Na+ and H + ZSM-5 zeolites.

    Science.gov (United States)

    Ferreira, L F Vieira; Costa, A I; Machado, I Ferreira; do Rego, A M Botelho; Sikorska, E; Sikorskie, M

    2009-07-21

    This work reports the surface photochemistry study of alloxazine adsorbed within nanochannels of MFI zeolites, namely in a series of Na+ and H+ ZSM-5 zeolites where the hydrophobic and hydrophilic character of the host varies systematically. Laser-induced room temperature and 77 K luminescence of air-equilibrated solid powdered samples of alloxazine adsorbed onto the two sets of zeolites, which we will name NaZSM-5 and HZSM-5, revealed the existence of a single emission of alloxazine as a broad band centred at about 450 nm in some cases, while in others an emission with a maximum at about 510 nm was detected. The decay times of the alloxazine emission vary greatly going from solution to entrapment within the nanochannels of the ZSM-5 zeolites. In the latter case a lifetime distribution analysis has shown that the longest lifetime for the alloxazine fluorescence emission exists in the case where an isoalloxazine-type emission was detected, i.e. whenever the hydrophobic character of the host increases. Alloxazine entrapped in the more acidic zeolites exists in the form of emissive monomers. However, alloxazine emits both from monomeric and aggregated emissive forms in the case of the hydrophobic zeolites. These data indicate the formation of planar dimers of alloxazine whenever the number of active sites in the zeolite decreases. These dimers have to be formed at the intersections of the zig-zag and linear nanochannels of the zeolite since there is no space available for their formation inside the zeolite channels. The isoalloxazine tautomers are formed due to the existence of alloxazine dimers which may undergo double proton transfer in the excited state, following laser excitation. Delayed fluorescence of alloxazine was also detected for the HZSM-5 and NaZSM-5 entrapment both at room temperature and at 77 K. The present study is paradigmatic as regards the host influence on the photochemistry of the guest.

  11. Structural characterization of a non-heme iron active site in zeolites that hydroxylates methane.

    Science.gov (United States)

    Snyder, Benjamin E R; Böttger, Lars H; Bols, Max L; Yan, James J; Rhoda, Hannah M; Jacobs, Ariel B; Hu, Michael Y; Zhao, Jiyong; Alp, E Ercan; Hedman, Britt; Hodgson, Keith O; Schoonheydt, Robert A; Sels, Bert F; Solomon, Edward I

    2018-04-02

    Iron-containing zeolites exhibit unprecedented reactivity in the low-temperature hydroxylation of methane to form methanol. Reactivity occurs at a mononuclear ferrous active site, α-Fe(II), that is activated by N 2 O to form the reactive intermediate α-O. This has been defined as an Fe(IV)=O species. Using nuclear resonance vibrational spectroscopy coupled to X-ray absorption spectroscopy, we probe the bonding interaction between the iron center, its zeolite lattice-derived ligands, and the reactive oxygen. α-O is found to contain an unusually strong Fe(IV)=O bond resulting from a constrained coordination geometry enforced by the zeolite lattice. Density functional theory calculations clarify how the experimentally determined geometric structure of the active site leads to an electronic structure that is highly activated to perform H-atom abstraction.

  12. Regioselective nitration of aromatic substrates in zeolite cages

    Indian Academy of Sciences (India)

    Unknown

    meet market demand, Choudary et al have achieved a zeolite-based methodology for the nitration of aromatic compounds.13 They have carried out nitration of toluene with various zeolite catalysts and zeolite beta of different Si/Al ratios. Zeolite beta has proved to be the best catalyst among the zeolites used in terms of ...

  13. Synthesis and testing of nanosized zeolite Y

    Science.gov (United States)

    Karami, Davood

    This work focuses on the synthesis and testing of nanosized zeolite Y. The synthesis formulations of faujasite-type structure of zeolite Y prepared in nanosized form are described. The synthetic zeolite Y is the most widely employed for the preparation of fluid catalytic cracking (FCC) catalysts. The synthesis of zeolite Y is very complicated process. The mean particle size of zeolite Y is 1800 nm. The major challenge of this work involved reducing this average particle size to less than 500 nm. The preliminary experiments were conducted to obtain the pure zeolite Y using the soluble silicates as a silica source. This was achieved by applying the experimental design approach to study the effects of many parameters. The ageing time turned out to be the most significant variable affecting product purity. Based on the preliminary results, a detailed investigation was carried out to determine the effects of silica-alumina precursor preparations on zeolite Y synthesis. Aluminosilicate precursors were prepared by gelling and precipitation of soluble silicate. The as-prepared precursors were used for the hydrothermal synthesis of zeolite Y. The procedure of the precipitation of soluble silicate yielded pure zeolite Y at the conventional synthesis conditions. The extent of purity of zeolite Y depends on the surface areas of aluminosilicate precursors. A novel approach to zeolite Y synthesis was employed for the preparation of the pure nanosized zeolite Y. This was achieved by applying the method of impregnation of precipitated silica. This novel method of impregnation for zeolite Y preparation allows eliminating the vigorous agitation step required for the preparation of a homogeneous silica solution, thereby simplifying the synthesis of zeolite Y in one single vessel. In case of the synthesis of nanosized zeolite Y, the effect of varying the organic templates on the formation of nanosized particles of zeolite Y was investigated, while all other reaction parameters were

  14. Direct activation of microcrystalline zeolites

    NARCIS (Netherlands)

    Ortiz-Iniesta, Maria Jesus; Heeres, Hero Jan; Melian-Cabrera, Ignacio

    2013-01-01

    In this work a direct activation route of zeolites is assessed. It consists of NH4-exchanging the as-synthesized solids before removing the organic template. Calcination afterwards serves to combust the organic template and creates the Bronsted sites directly; thus applying merely a single thermal

  15. Fixing noble gas in zeolites

    International Nuclear Information System (INIS)

    Rocha Dorea, A.L. da.

    1980-09-01

    In order to increase safety during the long-term storage of Kr-85 it has been proposed to encaosulate this gas in zeolite 5A. Due to the decay heat of Kr-85 it is expected, however, that the inorganic matrix will be at an increased temperature over several decades. Below 600 0 C only very small Kr-desorption rates are observed when a linear temperature gradient is applied to a loaded 5A zeolite sample. If heating is interrupted and the temperature kept konstant at a certain value (>600 0 C), it is observed that the desorption rate either decreased below the detection limit or stayed constant at some measurable value. The overall activation energy in the temperature range 570 0 C-745 0 C is found to be 250 kJ/mol. At temperature above 790 0 C the total encapsulated gas is rapidly liberated. No significant leakage was apparent from zeolite 5A samples containing between 19 and 57 cm 3 STP Kr/g kept at 200 0 C for up to 2500 h and 400 0 C for up to 3500 h. From these studies it is found that type 5A zeolites are particularly suitable as a matrix for the inmobilization of Kr-85. (Author) [pt

  16. Constraining models of postglacial rebound using space geodesy: a detailed assessment of model ICE-5G (VM2) and its relatives

    Science.gov (United States)

    Argus, Donald F.; Peltier, W. Richard

    2010-05-01

    Using global positioning system, very long baseline interferometry, satellite laser ranging and Doppler Orbitography and Radiopositioning Integrated by Satellite observations, including the Canadian Base Network and Fennoscandian BIFROST array, we constrain, in models of postglacial rebound, the thickness of the ice sheets as a function of position and time and the viscosity of the mantle as a function of depth. We test model ICE-5G VM2 T90 Rot, which well fits many hundred Holocene relative sea level histories in North America, Europe and worldwide. ICE-5G is the deglaciation history having more ice in western Canada than ICE-4G; VM2 is the mantle viscosity profile having a mean upper mantle viscosity of 0.5 × 1021Pas and a mean uppermost-lower mantle viscosity of 1.6 × 1021Pas T90 is an elastic lithosphere thickness of 90 km; and Rot designates that the model includes (rotational feedback) Earth's response to the wander of the North Pole of Earth's spin axis towards Canada at a speed of ~1° Myr-1. The vertical observations in North America show that, relative to ICE-5G, the Laurentide ice sheet at last glacial maximum (LGM) at ~26 ka was (1) much thinner in southern Manitoba, (2) thinner near Yellowknife (Northwest Territories), (3) thicker in eastern and southern Quebec and (4) thicker along the northern British Columbia-Alberta border, or that ice was unloaded from these areas later (thicker) or earlier (thinner) than in ICE-5G. The data indicate that the western Laurentide ice sheet was intermediate in mass between ICE-5G and ICE-4G. The vertical observations and GRACE gravity data together suggest that the western Laurentide ice sheet was nearly as massive as that in ICE-5G but distributed more broadly across northwestern Canada. VM2 poorly fits the horizontal observations in North America, predicting places along the margins of the Laurentide ice sheet to be moving laterally away from the ice centre at 2 mm yr-1 in ICE-4G and 3 mm yr-1 in ICE-5G, in

  17. Hydrogen Selective Exfoliated Zeolite Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Tsapatsis, Michael [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Daoutidis, Prodromos [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Elyassi, Bahman [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Lima, Fernando [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Iyer, Aparna [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Agrawal, Kumar [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science; Sabnis, Sanket [Univ. of Minnesota, Minneapolis, MN (United States). Department of Chemical Engineering and Materials Science

    2015-04-06

    The objective of this project was to develop and evaluate an innovative membrane technology at process conditions that would be representative of Integrated Gasification Combined Cycle (IGCC) advanced power generation with pre-combustion capture of carbon dioxide (CO2). This research focused on hydrogen (H2)-selective zeolite membranes that could be utilized to separate conditioned syngas into H2-rich and CO2-rich components. Both experiments and process design and optimization calculations were performed to evaluate the concept of ultra-thin membranes made from zeolites nanosheets. In this work, efforts in the laboratory were made to tackle two fundamental challenges in application of zeolite membranes in harsh industrial environments, namely, membrane thickness and membrane stability. Conventional zeolite membranes have thicknesses in the micron range, limiting their performance. In this research, we developed a method for fabrication of ultimately thin zeolite membranes based on zeolite nanosheets. A range of layered zeolites (MWW, RWR, NSI structure types) suitable for hydrogen separation was successfully exfoliated to their constituent nanosheets. Further, membranes were made from one of these zeolites, MWW, to demonstrate the potential of this group of materials. Moreover, long-term steam stability of these zeolites (up to 6 months) was investigated in high concentrations of steam (35 mol% and 95 mole%), high pressure (10 barg), and high temperatures (350 °C and 600 °C) relevant to conditions of water-gas-shift and steam methane reforming reactions. It was found that certain nanosheets are stable, and that stability depends on the concentration of structural defects. Additionally, models that represent a water-gas-shift (WGS) membrane reactor equipped with the zeolite membrane were developed for systems studies. These studies had the aim of analyzing the effect of the membrane reactor integration into IGCC plants

  18. Pure zeolite exchange to synthetic zeolite characterized by XRD to produce cation exchange materials

    International Nuclear Information System (INIS)

    Zainab Ramli; Dewi Jamaliah Kamsiar; Hasidah Mohd Arsat

    2008-01-01

    In this study, natural mordenite was modified to other zeolites phases having low Si/ Al in order to increase the cation exchange capacity of the material. Modification was carried out hydrothermally at 100 degree Celsius in time range between 0 to 24 hours. The samples obtained were characterized by XRD and infrared spectroscopy. Results showed that a mixture of zeolite X and P were formed zeolite X was the dominant zeolite at 6 hrs heating time while zeolite P were dominant after 6 hrs. Ion Exchange capacity of natural mordenite, samples at 6 hr and 24 hrs heating, performed using Ca 2+ cation gave cation exchange in the decreasing order of 83.57 % , 72.50 %, 69.45 % for sample 24 hrs, 6 hrs and natural mordenite respectively. It indicates that sample having zeolite P phase is the best cation exchange capacity with 21 mg Ca 2+ / g zeolite with an increased of 23 % capacity compared to natural zeolite. (author)

  19. Spin probes of chemistry in zeolites

    International Nuclear Information System (INIS)

    Werst, D.W.; Trifunac, A.D.

    1997-09-01

    Electron spin resonance (EPR) studies in zeolites are reviewed in which radiolysis was used to ionize the zeolite lattice, create reactive intermediates, spin label reaction products and to provide a window onto chemistry and transport of adsorbates and matrix control of chemistry. The review examines reactions of radical cations and the influence of the geometry constraints inside the zeolite, explores how zeolite model systems can be used to learn about energy and charge transfer in solids and illustrates the use of radiolysis and EPR for in situ spectroscopic studies of solid-acid catalysis. The various spin probes created inside the zeolite pores report on properties of the zeolites as well as shed light on radiolytic processes

  20. Gas-phase adsorption in dealuminated natural clinoptilolite and liquid-phase adsorption in commercial DAY zeolite and modified ammonium Y zeolite

    Science.gov (United States)

    Costa Hernandez, Alba Nydia

    The adsorption of Carbon Dioxide (CO2) is a very important tool for the material characterization. On the other hand, in separation and recovery technology, the adsorption of the CO2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied to eliminate some pollutants from the environment. One of the goals of this research is to study the structure, composition and morphology of one natural clinoptilolite dealuminated with ammonium hexafluorosilicate (AHFi) and with orthophosphoric acid (H3PO4). Each modified sample was characterized using X-ray Diffraction (XRD), Carbon Dioxide adsorption at 0° C, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDAX). In addition, the surface chemistry of the modified clinoptilolites was analyzed with Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The adsorption measurements were also used to study of the interaction of CO2 molecule within the adsorption space of these modified clinoptilolites. It was concluded that one of the modified clinoptilolites, (CSW-HFSi-0.1M), showed a great quality as adsorbent and as catalytic comparable to commercial synthetic zeolites. As far as we know, the modification of clinoptilolite with HFSi to improve their adsorption properties had not been previously attempted. In the second part of this dissertation, the dynamic adsorption of three isomers of nitrophenols using as adsorbent a commercial DAY zeolite was investigated. Also, the dynamic adsorption of methanol in a less hydrophobic zeolite, Ammonium Y Zeolite was investigated. The obtained breakthrough curves showed that the commercial DAY zeolite could be a suitable adsorbent to the liquid-phase adsorption of the phenolic compounds. Notwithstanding the modified ammonium Y zeolite had a low Si/Al ratio (less hydrophobic) than commercial DAY zeolite; this

  1. Synthesis, Characterization and Application of Hydrophobic Zeolites

    OpenAIRE

    Heidari, Rulis

    2016-01-01

    The aim of the thesis was to design and synthesize a type of zeolite with the characteristics of hydrophobicity, high porosity, and proper pore size, which can be used for high-performance adsorption of ethanol from aqueous solution. In addition, the aim was to synthesize hydrophobic microporous zeolites including theoretic and experimental content. The experiment was carried out using hydroxide basic system and hydrogen fluoride neutral based on hydrothermal methods. Pure silica zeolites...

  2. 85Kr storage by zeolite encapsulation

    International Nuclear Information System (INIS)

    Brown, R.A.; Hoza, M.; Knecht, D.A.

    1976-01-01

    The technology of 85 Kr storage by zeolite encapsulation is described. The prcess of encapsulation takes place at high temperatures and pressures, and involves the activated diffusion of krypton into zeolite cages. Experimental results for krypton encapsulation in various zeolites are reviewed and discussed. Activated diffusion parameters determined by measuring krypton leakage rates from zeolites at high temperatures and low pressures are used to estimate leakage rates of 85 Kr during long-term storage. The potential safety benefits are determined for krypton-85 storage by encapsulation in sodalite. Requirements for pilot-scale and process-scale development are discussed briefly

  3. Increased thermal conductivity monolithic zeolite structures

    Science.gov (United States)

    Klett, James; Klett, Lynn; Kaufman, Jonathan

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  4. Mesoporous zeolite single crystal catalysts: Diffusion and catalysis in hierarchical zeolites

    DEFF Research Database (Denmark)

    Christensen, Christina Hviid; Johannsen, Kim; Toernqvist, Eric

    2007-01-01

    in the zeolite micropores. Here, we briefly discuss the most important ways of introducing mesopores into zeolites and, for the first time, we show experimentally that the presence of mesopores dramatically increases the rate of diffusion in zeolite catalysts. This is done by studying the elution of iso-butane...... from packed beds of conventional and mesoporous zeolite catalysts. Moreover, we discuss in detail the recent observation of improved activity and selectivity in the alkylation of benzene with ethene using mesoporous zeolite single crystal catalysts. For this reaction, we show by calculation...

  5. Selective adsorption of bacterial cells onto zeolites.

    Science.gov (United States)

    Kubota, Munehiro; Nakabayashi, Tadashi; Matsumoto, Yuki; Shiomi, Tohru; Yamada, Yusuke; Ino, Keita; Yamanokuchi, Hiroyuki; Matsui, Masayoshi; Tsunoda, Tatsuo; Mizukami, Fujio; Sakaguchi, Kengo

    2008-06-15

    Zeolites adsorb microbial cells on their surfaces and selective adsorption for specific microorganisms was seen with certain zeolites. Tests for the adsorption ability of zeolites were conducted using various established microbial cell lines. Specific cell lines were shown to selectively absorb to certain zeolites, species to species. In order to understand the selectivity of adsorption, we tested adsorption under various pH conditions and determined the zeta-potentials of zeolites and cells. The adsorption of some cell lines depended on the pH, and some microorganisms were preferentially adsorbed at acidic pH. The values of zeta-potentials were used for calculating the electric double layer interaction energy between zeolites and microbial cells. There was a correlation between the experimental adsorption results and the interaction energy. Moreover, we evaluated the surface hydrophobicity of bacterial cells by using the microbial adherence to hydrocarbon (MATH) assay. In addition, we also applied this method for zeolites to quantify relative surface hydrophobicity. As a result, we found a correlation between the adsorption results and the hydrophobicity of bacterial cells and zeolites. These results suggested that adsorption could be explained mainly by electric double layer interactions and hydrophobic interactions. Finally, by using the zeolites Na-BEA and H-Y, we succeeded in clearly separating three representative microbes from a mixture of Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Zeolites could adsorb each of the bacterial cell species with high selectivity even from a mixed suspension. Zeolites can therefore be used as effective carrier materials to provide an easy, rapid and accurate method for cell separation.

  6. Zeolite from fly ash: synthesis and characterization

    Indian Academy of Sciences (India)

    Coal fly ash was used to synthesize X-type zeolite by alkali fusion followed by hydrothermal treatment. The synthesized zeolite was characterized using various techniques such as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, BET method for surface area measurement etc.

  7. Magnetically supported zeolite adsorbents for effluent treatment

    International Nuclear Information System (INIS)

    Gaydardjiev, S.

    1998-01-01

    An attempt was made to remove heavy metal ions from metallurgical effluents by means of magnetically supported fluidized bed column employing zeolite-magnetite complexes as adsorbents. The natural sorptive properties of acid modified clinoptilolite were used instead of synthetic beads. X-ray diffraction and DTA studies on the raw material confirmed that the main zeolite mineral was clinoptilolite. (author)

  8. Geopolymer materials based on natural zeolite

    NARCIS (Netherlands)

    Nikolov, A.; Rostovsky, Ivan; Nugteren, H.W.

    2017-01-01

    One of the potential raw materials for preparation of geopolymers is the natural zeolite. In the present report, the used natural zeolite (clinoptilolite) is from huge deposit near Beli Plast, Bulgaria. Geopolymer pastes and mortars are prepared by using three different alkaline activators—sodium

  9. ETHIOPIAN NATURAL ZEOLITES FOR PHOTOCATALYSIS Kiros ...

    African Journals Online (AJOL)

    B. S. Chandravanshi

    This sample, called ET4, contains other non-zeolitic phases like celadonite and ilmenite, which may synergize the potential application of this high Ti- containingsample for photocatalysis. EXPERIMENTAL. Sample preparation. Three different approaches were carried out: i) simple calcination of raw zeolite ET4 sample: 1.

  10. Zeolite from fly ash: synthesis and characterization

    Indian Academy of Sciences (India)

    Unknown

    disposal or to minimize the environmental impact. One of the approaches is the conversion of fly ash to zeolites, which have wide applications in ion exchange, as mole- cular sieves, catalysts, and adsorbents (Breck 1974). The present study is concerned with the synthesis of zeolite from coal fly ash and its characterization ...

  11. Synthesis of LTA zeolite for bacterial adhesion

    Directory of Open Access Journals (Sweden)

    Raja Belaabed

    2016-07-01

    X-ray diffraction, environmental scanning electron microscope and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the synthesized zeolite. To evaluate the bacterial adhesion to zeolite LTA the hydrophobicity and surface properties are examined using contact angle measurement.

  12. Exfoliation of two-dimensional zeolites in liquid polybutadienes

    KAUST Repository

    Sabnis, Sanket

    2017-06-16

    Layered zeolite precursors were successfully exfoliated by brief shearing or sonication with the assistance of commercially available telechelic liquid polybutadienes at room temperature. The exfoliated zeolite nanosheets can form a stable suspension in an organic solvent, providing exciting potential for the fabrication of zeolite membranes, composite materials and hierarchical zeolites.

  13. Nuclear waste treatment using Iranian natural zeolites

    International Nuclear Information System (INIS)

    Kazemian, H.; Ghannadi Maraghe, M.

    2001-01-01

    Full text: The zeolite researches in Iran is a relatively new subject which has started about 10 years ago. The motivation for this scientific and interesting field was provided after discovery of significant deposits of natural zeolites in different regions of Iran as well as further developments of research institutions and the national concern to environmental protection especially the wastewater clean-up in point of view of recycling of such waste water to compensate some needs to water in other utilizations. This paper intends to review and describes scientific researches which have done on using zeolites in the field of nuclear waste treatment in Iran to introduce the potential resources to the world in more details. Zeolite tuffs are widely distributed in huge deposits in different regions of Iran. So far, the clinoptilolite tuffs are the most abundant natural zeolite which exist with zeolite content of 65%- 95%. Nowadays several different types of Iranian natural zeolites are characterized in point of view of chemical composition, type of structure, chemical, thermal, and radiation resistance using different instrumental and classical methods such as; X-ray diffraction (XRD), X-ray fluoresce (XRF), thermal methods of analysis (TA), scanning electron microscopy (SEM), analytical chemistry and radioanalytical methods as well as different ion-exchange techniques (e.g.3-7). The ability of Iranian natural clinoptilolite for removal of some fission products from nuclear wastewaters have been investigated. The selectivity of all investigated zeolites toward radiocesium and radiostrontium have been promising (e.g. 8-10). The successful synthesize of P zeolite from Iranian clinoptilolite-reach tuffs under different conditions were performed. The compatibility of zeolites with glass and cement matrices, for final disposal of radwaste, as well as their selectivity toward most dangerous heat generating radionuclides (e.g. 137 Cs and 90 Sr) is very important in using

  14. Catalytic Cracking of Palm Oil Over Zeolite Catalysts: Statistical Approach

    Directory of Open Access Journals (Sweden)

    F. A. A. Twaiq and S. Bhatia

    2012-08-01

    Full Text Available The catalytic cracking of palm oil was conducted in a fixed bed micro-reactor over HZSM-5, zeolite ? and ultrastable Y (USY zeolite catalysts. The objective of the present investigation was to study the effect of cracking reaction variables such as temperature, weight hourly space velocity, catalyst pore size and type of palm oil feed of different molecular weight on the conversion, yield of hydrocarbons in gasoline boiling range and BTX aromatics in the organic liquid product.  Statistical Design of Experiment (DOE with 24 full factorial design was used in experimentation at the first stage.  The nonlinear model and Response Surface Methodology (RSM were utilized in the second stage of experimentation to obtain the optimum values of the variables for maximum yields of hydrocarbons in gasoline boiling range and aromatics.  The HZSM-5 showed the best performance amongst the three catalysts tested.  At 623 K and WHSV of 1 h-1, the highest experimental yields of gasoline and aromatics were 28.3 wt.% and 27 wt.%, respectively over the HZSM-5 catalyst.  For the same catalyst, the statistical model predicted that the optimum yield of gasoline was 28.1 wt.% at WHSV of 1.75 h-1 and 623 K.  The predicted optimum yield of gasoline was 25.5 wt.% at 623 K and WHSV of 1 h-1.KEY WORDS: Catalytic Cracking, Palm Oil, Zeolite, Design Of Experiment, Response Surface Methodology.

  15. Zeolitic materials with hierarchical porous structures.

    Science.gov (United States)

    Lopez-Orozco, Sofia; Inayat, Amer; Schwab, Andreas; Selvam, Thangaraj; Schwieger, Wilhelm

    2011-06-17

    During the past several years, different kinds of hierarchical structured zeolitic materials have been synthesized due to their highly attractive properties, such as superior mass/heat transfer characteristics, lower restriction of the diffusion of reactants in the mesopores, and low pressure drop. Our contribution provides general information regarding types and preparation methods of hierarchical zeolitic materials and their relative advantages and disadvantages. Thereafter, recent advances in the preparation and characterization of hierarchical zeolitic structures within the crystallites by post-synthetic treatment methods, such as dealumination or desilication; and structured devices by in situ and ex situ zeolite coatings on open-cellular ceramic foams as (non-reactive as well as reactive) supports are highlighted. Specific advantages of using hierarchical zeolitic catalysts/structures in selected catalytic reactions, such as benzene to phenol (BTOP) and methanol to olefins (MTO) are presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Si/Al Ratio of Zeolites

    Directory of Open Access Journals (Sweden)

    Moses Wazingwa Munthali

    2014-12-01

    Full Text Available In addition to their well-known uses as catalysts, zeolites are utilized to adsorb and remove various cations from aqueous system. The adsorption of the cations is ascribed to the negative charge of zeolites derived from isomorphous substitution of Si by Al. The amount of Na+ adsorption on 4A, X, Y, Na-P1 and mordenite type zeolites were determined in aqueous media, in a two-cation (Na+ and H+ system. Although each zeolite has a constant amount of negative charge, the amount of Na+ adsorption of each zeolite decreased drastically at low pH−pNa values, where pH−pNa is equal to log{(Na+/(H+}. By using the plot of the amount of Na+ adsorption versus pH−pNa, an index of the H+ selectivity, which is similar to the pKa of acids, of each zeolite was estimated, and the index tended to increase with decreasing Si/Al ratio of zeolites. These indicate that zeolites with lower Si/Al and higher negative charge density have higher H+ adsorption selectivity, and in fact, such a zeolite species (4A and X adsorbed considerable amount of H+ even at weakly alkaline pH region. The adsorption of H+ results in the decrease of cation adsorption ability, and may lead to the dissolution of zeolites in aqueous media.

  17. Selective Production of Aromatics from 2-Octanol on Zinc Ion-Exchanged MFI Zeolite Catalysts

    OpenAIRE

    Iwamoto, Masakazu; Takezawa, Ryota; Morimoto, Masao

    2015-01-01

    The aromatization of 2-octanol derived from castor oil as a byproduct in the formation of sebacic acid was investigated on various zeolite catalysts. Zn ion-exchanged MFI (ZSM-5) zeolites with small silica/alumina ratios and zinc contents of 0.5 to 2.0 wt. % were determined to exhibit good and stable activity for the reaction at 623 to 823 K. The yield of aromatics was 62% at 773 K and the space velocity 350 to 1400 h−1. The temperature and contact time dependences of the product distribution...

  18. Water nanodroplets confined in zeolite pores.

    Science.gov (United States)

    Coudert, François-Xavier; Cailliez, Fabien; Vuilleumier, Rodolphe; Fuchs, Alain H; Boutin, Anne

    2009-01-01

    We provide a comprehensive depiction of the behaviour of a nanodroplet of approximately equal to 20 water molecules confined in the pores of a series of 3D-connected isostructural zeolites with varying acidity, by means of molecular simulations. Both grand canonical Monte Carlo simulations using classical interatomic forcefields and first-principles Car-Parrinello molecular dynamics were used in order to characterise the behaviour of confined water by computing a range of properties, from thermodynamic quantities to electronic properties such as dipole moment, including structural and dynamical information. From the thermodynamic point of view, we have identified the all-silica zeolite as hydrophobic, and the cationic zeolites as hydrophilic; the condensation transition in the first case was demonstrated to be of first order. Furthermore, in-depth analysis of the dynamical and electronic properties of water showed that water in the hydrophobic zeolite behaves as a nanodroplet trying to close its hydrogen-bond network onto itself, with a few short-lived dangling OH groups, while water in hydrophilic zeolites "opens up" to form weak hydrogen bonds with the zeolite oxygen atoms. Finally, the dipole moment of confined water is studied and the contributions of water self-polarisation and the zeolite electric field are discussed.

  19. The role of zeolite in the Fischer–Tropsch synthesis over cobalt–zeolite catalysts

    International Nuclear Information System (INIS)

    Sineva, L V; Mordkovich, V Z; Asalieva, E Yu

    2015-01-01

    The review deals with the specifics of the Fischer–Tropsch synthesis for the one-stage syncrude production from CO and H 2 in the presence of cobalt–zeolite catalytic systems. Different types of bifunctional catalysts (hybrid, composite) combining a Fischer–Tropsch catalyst and zeolite are reviewed. Special attention focuses on the mechanisms of transformations of hydrocarbons produced in the Fischer–Tropsch process on zeolite acid sites under the synthesis conditions. The bibliography includes 142 references

  20. A general method to incorporate metal nanoparticles in zeolites and zeotypes

    DEFF Research Database (Denmark)

    2015-01-01

    Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure.......Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure....

  1. Analysis Of Natural Zeolites For Technical Nuclear

    International Nuclear Information System (INIS)

    Sarria, P.; Desdin, L.; Dominguez, O.

    1999-01-01

    In this article a methodology of elementary analysis of natural zeolites is reported using different technical nuclear (AANR, FRX, MRN and EG). Determines the elementary composition of ours of two Cuban locations. (Author) [es

  2. Enriched natural zeolites – mineral fertilizer

    Directory of Open Access Journals (Sweden)

    Rybárová Lucia

    2001-12-01

    Full Text Available Clinoptilolit belongs to the big group of minerals called zeolites. Chemically they are alumosilicates and have a very difficult crystal structure. Nature zeolites are used as sorbents, molecular sieves and catalyzators. Their application is also in agriculture and horticulture. Endeavour of all agricurtural subjects from the plant area is to reach a maximum efficiency and production.Charges for the fertilization are 14 – 40% of all charges depending on the structure of product, intensity of production and share of nutrition in soil. For the elimination of the loss in the nutrition matter, it is possible to use a „porter“, which secures a regular and inteligent supply of nutrition to plants.Regarding the physical and chemical properties is good to use natural zeolites as a „porter“.The experiments were made with enriched zeolites, and their influences an vegetables and flowers roots was reserched. Results were positive.

  3. Diagenetic Quartz Morphologies and Zeolite formation

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Hansen, Rikke Weibel; Friis, Henrik

    sands in these wells all contain authigenic silica/quartz of various morphologies identified with a combination of traditional optical microscopy and scanning electron microscopy. Late Paleocene–early Eocene volcanic ash layers are recognized throughout most of the North Sea and also recorded from......, the precipitation of zeolite may later facilitate further quartz cementation, which might otherwise be retarded by the presence of disordered microquartz. The silica activity of pore fluids can influence zeolite precipitation.  Although zeolite formation is clearly related to volcanic ash, zeolite has also formed...... are abundant in some of associated shales; and 2) volcanic ash. The dissolution of biogenic silica may result in a rapid release of silica thereby promoting the formation of diagenetic opal/microquartz, but there may be a limited release of Al. A limited release of Al may result in precipitation of Si...

  4. The thermal dehydration of natural zeolites

    NARCIS (Netherlands)

    Reeuwijk, van L.P.

    1974-01-01

    The zeolites constitute a group of minerals of much interest from geological, mineralogical and technological points of view. Structurally, they are tectosilicates with an 'open' framework containing channels and cavities which accommodate cations and water molecules. Generally, these

  5. Synthesis of LTA zeolite for bacterial adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Belaabed, R.; Eabed, S.; Addaou, A.; Laajab, A.; Rodriguez, M.A.; Lahsini, A.

    2016-07-01

    High affinity and adhesion capacity for Gram-positive bacteria on minerals has been widely studied. In this work the adhesion of bacteria on synthesized zeolite has been studied. The Zeolite Linde Type A (LTA) has been synthesized using hydrothermal route using processing parameters to obtain low cost materials. For adhesion studies Staphylococcus aureus and Bacillus subtilis were used as Gram-positive bacteria, Escherichia coli and Pseudomonas aeruginosa are used as Gram-negative bacteria. X-ray diffraction, environmental scanning electron microscope and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the synthesized zeolite. To evaluate the bacterial adhesion to zeolite LTA the hydrophobicity and surface properties are examined using contact angle measurement. (Author)

  6. Mixing of zeolite powders and molten salt

    International Nuclear Information System (INIS)

    Pereira, C.; Zyryanov, V.N.; Lewis, M.A.; Ackerman, J.P.

    1996-01-01

    Transuranics and fission products in a molten salt can be incorporated into zeolite A by an ion exchange process and by a batch mixing or blending process. The zeolite is then mixed with glass and consolidated into a monolithic waste form for geologic disposal. Both processes require mixing of zeolite powders with molten salt at elevated temperatures (>700 K). Complete occlusion of salt and a uniform distribution of chloride and fission products are desired for incorporation of the powders into the final waste form. The relative effectiveness of the blending process was studied over a series of temperature, time, and composition profiles. The major criteria for determining the effectiveness of the mixing operations were the level and uniformity of residual free salt in the mixtures. High operating temperatures (>775 K) improved salt occlusion. Reducing the chloride levels in the mixture to below 80% of the full salt capacity of the zeolite significantly reduced the free salt level in the final product

  7. Zeolite membranes for efficient synthesis of biofuels

    OpenAIRE

    Sandström, Linda

    2009-01-01

    The greenhouse effect and the limited fossil oil resources have increased the demand of renewable fuels. Zeolite membranes have potential applications in numerous separation processes, and could be useful in the development of efficient processes for renewable fuel production. Methanol synthesis from synthesis gas is equilibrium limited, and continuous removal of products in a zeolite membrane reactor could improve the productivity of a conventional methanol synthesis process. In this work, m...

  8. Zeolitic catalytic conversion of alcohols to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2018-04-10

    A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

  9. Zeolitic catalytic conversion of alochols to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2017-01-03

    A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

  10. The Catalytic Activity of Modified Zeolite Lanthanum on the Catalytic Cracking of Al-Duara Atmospheric Distillation Residue

    Directory of Open Access Journals (Sweden)

    Karim Khalifa Esgair

    2016-03-01

    Full Text Available Atmospheric residue fluid catalytic cracking was selected as a probe reaction to test the catalytic performance of modified NaY zeolites and prepared NaY zeolites. Modified NaY zeolites have been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with lanthanum and the weight percent added are 0.28, 0.53, and 1.02 respectively. The effects of addition of lanthanum to zeolite Y in different weight percent on the cracking catalysts were investigated using an experimental laboratory plant scale of fluidized bed reactor. The experiments have been performed with weight hourly space velocity (WHSV range of 6 to 24 h-1, and the range of temperature from 450 to 510 oC. The activity of the catalyst with 1.02 wt% lanthanum has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the lanthanum causes an increase in the thermal stability of the zeolite.

  11. Investigating the Influence of the Cerium loading in prepared Y zeolite from Iraqi kaolin on its Catalytic Performance

    Directory of Open Access Journals (Sweden)

    Karim Khalifa Esgair

    2018-01-01

    Full Text Available In this study, the effects of different loading doses of cerium in the prepared NaY zeolite from Iraqi kaolin were investigated. Al-Duara refinery atmospheric residue fluid catalytic cracking was selected as palpation reaction for testing the catalytic activity of cerium loading NaY zeolite. The insertion of cerium in NaY zeolites has been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with cerium and the weight percent added are 0.35, 0.64, and 1.06 respectively. The effects of cerium loading to zeolite Y in different weight percent on the cracking catalysts were studied by employing a laboratory fluidized bed reactor. The experiments have been performed with weight hourly space velocity (WHSV range from 6 to 24 h-1, and the temperature range from 450 to 510 oC. The activity of the catalyst with 1.06 wt% cerium has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the cerium causes an increase in the thermal stability of the zeolite.

  12. Effect of pore confinement on the adsorption of mono-branched alkanes of naphtha in ZSM-5 and Y zeolites

    Science.gov (United States)

    Fu, Jia; Feng, Xiang; Liu, Yibin; Yang, Chaohe

    2017-11-01

    Branched alkanes are important parts of naphtha, and their conversions are related to the adsorption stabilities in the pore of zeolites. In this work, the adsorption stabilities of C7-C10 mono-branched alkanes in the pores of HY (ca. 0.74 nm) and HZSM-5 (ca. 0.55 nm) zeolites are investigated using DFT calculation. After excluding the effect of Brønsted acid by subtracting the adsorption energy on 8T cluster from the total adsorption energy, it is found that confinement effect plays an essential role in stabilizing mono-branched alkanes. With the increase in the carbon number of alkanes, there is gradual increase of adsorption energy on both HZSM-5 and HY zeolites. Moreover, in the narrow channel of HZSM-5 zeolite, the change of adsorption energy (ethyl-alkane methyl-alkane > n-alkane), which is mainly due to confinement effect rather than effect of Brønsted acid. Methyl-alkanes prefer to stay in the pore of HZSM-5, while ethyl-alkanes and propyl-alkanes are more likely absorbed in the pore of HY zeolite. By analyzing the total electron densities of adsorbates, it is concluded that only when there is a certain distance between zeolite fragment and the adsorbate and low electron density region occupies the remaining space of the pore, the confinement effect is the strongest.

  13. Synthesis and characterization of zeolite L

    International Nuclear Information System (INIS)

    Ko, Yong Sig; Ahn, Wha Seung

    1999-01-01

    Substantial reduction in synthesis time was achieved for zeolite L crystallization by attempting a hydrothermal synthesis at elevated temperature of 443K in a Na + /K+ mixed alkali system. Pure zeolite L could be obtained from a gel with the molar composition 5.4K 2 O-5.7Na 2 O-Al 2 O 3 -30SiO 2 -500H 2 O after 24h. Zeolite L could be obtained in high purity at the optimum Na 2 O/(K 2 O+Na 2 O) ratio of around 0.5, while zeolite W was formed when the Na 2 O/(K 2 O+Na 2 O) ratio was more than 0.66. The crystalline zeolite L samples obtained were characterized by means of elemental chemical analysis, XRD, SEM, FTi.r. spectroscopy, and particle size analyzer. In addition, two probe reaction studies were conducted. In toluene alkylation, H-L catalyst showed high catalytic activity at the beginning, but was deactivated quickly probably due to one-dimensional pore structure being blocked by the coke formed. High amounts of trimethylbenzene or diethylbenzene were observed due to the large 12-membered ring pore structure of zeolite L. Pt/NaKL catalyst prepared showed a high conversion of n-hexane and high selectivity to benzene in n-hexane aromatization reaction

  14. Thermal Properties of Zeolite-Containing Composites.

    Science.gov (United States)

    Shimonosono, Taro; Hirata, Yoshihiro; Nishikawa, Kyohei; Sameshima, Soichiro; Sodeyama, Kenichi; Masunaga, Takuro; Yoshimura, Yukio

    2018-03-13

    A zeolite (mordenite)-pore-phenol resin composite and a zeolite-pore-shirasu glass composite were fabricated by hot-pressing. Their thermal conductivities were measured by a laser flash method to determine the thermal conductivity of the monolithic zeolite with the proposed mixing rule. The analysis using composites is useful for a zeolite powder with no sinterability to clarify its thermal properties. At a low porosity thermal conductivity of the composite was in excellent agreement with the calculated value for the structure with phenol resin or shirasu glass continuous phase. At a higher porosity above 40%, the measured value approached the calculated value for the structure with pore continuous phase. The thermal conductivity of the monolithic mordenite was evaluated to be 3.63 W/mK and 1.70-2.07 W/mK at room temperature for the zeolite-pore-phenol resin composite and the zeolite-pore-shirasu glass composite, respectively. The analyzed thermal conductivities of monolithic mordenite showed a minimum value of 1.23 W/mK at 400 °C and increased to 2.51 W/mK at 800 °C.

  15. Properties of glass-bonded zeolite monoliths

    International Nuclear Information System (INIS)

    Lewis, M.A.; Fischer, D.F.; Murphy, C.D.

    1994-01-01

    It has been shown that mineral waste forms can be used to immobilize waste salt generated during the pyrochemical processing of spent fuel from the Integral Fast Reactor (IFR). Solid, leach resistant monoliths were formed by hot-pressing mixtures of salt-occluded zeolite A powders and glass frit at 990 K and 28 MPa. Additional samples have now been fabricated and tested. Normalized release rates for all elements, including iodide and chloride, were less than 1 g/m 2 d in 28-day tests in deionized water and in brine at 363 K (90 degrees C). Preliminary results indicate that these rates fall with time with both leachants and that the zeolite phase in the glass-bonded zeolite does not function as an ion exchanger. Some material properties were measured. The Poisson ratio and Young's modulus were slightly smaller in glass-bonded zeolite than in borosilicate glass. Density depended on zeolite fraction. The glass-bonded zeolite represents a promising mineral waste form for IFR salt

  16. Evolutionary constrained optimization

    CERN Document Server

    Deb, Kalyanmoy

    2015-01-01

    This book makes available a self-contained collection of modern research addressing the general constrained optimization problems using evolutionary algorithms. Broadly the topics covered include constraint handling for single and multi-objective optimizations; penalty function based methodology; multi-objective based methodology; new constraint handling mechanism; hybrid methodology; scaling issues in constrained optimization; design of scalable test problems; parameter adaptation in constrained optimization; handling of integer, discrete and mix variables in addition to continuous variables; application of constraint handling techniques to real-world problems; and constrained optimization in dynamic environment. There is also a separate chapter on hybrid optimization, which is gaining lots of popularity nowadays due to its capability of bridging the gap between evolutionary and classical optimization. The material in the book is useful to researchers, novice, and experts alike. The book will also be useful...

  17. Salt-occluded zeolite waste forms: Crystal structures and transformability

    International Nuclear Information System (INIS)

    Richardson, J.W. Jr.

    1996-01-01

    Neutron diffraction studies of salt-occluded zeolite and zeolite/glass composite samples, simulating nuclear waste forms loaded with fission products, have revealed complex structures, with cations assuming the dual roles of charge compensation and occlusion (cluster formation). These clusters roughly fill the 6--8 angstrom diameter pores of the zeolites. Samples are prepared by equilibrating zeolite-A with complex molten Li, K, Cs, Sr, Ba, Y chloride salts, with compositions representative of anticipated waste systems. Samples prepared using zeolite 4A (which contains exclusively sodium cations) as starting material are observed to transform to sodalite, a denser aluminosilicate framework structure, while those prepared using zeolite 5A (sodium and calcium ions) more readily retain the zeolite-A structure. Because the sodalite framework pores are much smaller than those of zeolite-A, clusters are smaller and more rigorously confined, with a correspondingly lower capacity for waste containment. Details of the sodalite structures resulting from transformation of zeolite-A depend upon the precise composition of the original mixture. The enhanced resistance of salt-occluded zeolites prepared from zeolite 5A to sodalite transformation is thought to be related to differences in the complex chloride clusters present in these zeolite mixtures. Data relating processing conditions to resulting zeolite composition and structure can be used in the selection of processing parameters which lead to optimal waste forms

  18. Theoretical investigation of layered zeolite frameworks: Surface properties of 2D zeolites

    Czech Academy of Sciences Publication Activity Database

    Hermann, Jan; Trachta, Michal; Nachtigall, P.; Bludský, Ota

    2014-01-01

    Roč. 227, May 15 (2014), s. 2-8 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 Keywords : layered zeolite frameworks * surface properties * 2D zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  19. Methylene blue removal from contaminated waters using O3, natural zeolite, and O3/zeolite.

    Science.gov (United States)

    Valdés, H; Tardón, R F; Zaror, C A

    2009-01-01

    This paper compares experimental results on methylene blue (MB) removal systems based on ozone oxidation, zeolite adsorption, and simultaneous adsorption-oxidation using ozone in the presence of natural zeolite. The effect of pH (2-8), and the presence of radical scavengers (sodium acetate) on process rates and removal efficiencies are assessed at laboratory scale. The experimental system consisted of a 1 L differential circular flow reactor and an ozone generator rated at 5 g O3/h. Results show that ozone oxidation combined with zeolite adsorption increases the overall MB oxidation rate with respect to ozonation process and zeolite adsorption. In presence of free radical scavenger, only a 25% of reduction on MB removal rate are observed in the simultaneous treatment, as compared with 70% when ozonation treatment is used, suggesting that MB oxidation reactions take mainly place on the zeolite surface.

  20. La roca magica: uses of natural zeolites in agriculture and industry.

    Science.gov (United States)

    Mumpton, F A

    1999-03-30

    For nearly 200 years since their discovery in 1756, geologists considered the zeolite minerals to occur as fairly large crystals in the vugs and cavities of basalts and other traprock formations. Here, they were prized by mineral collectors, but their small abundance and polymineralic nature defied commercial exploitation. As the synthetic zeolite (molecular sieve) business began to take hold in the late 1950s, huge beds of zeolite-rich sediments, formed by the alteration of volcanic ash (glass) in lake and marine waters, were discovered in the western United States and elsewhere in the world. These beds were found to contain as much as 95% of a single zeolite; they were generally flat-lying and easily mined by surface methods. The properties of these low-cost natural materials mimicked those of many of their synthetic counterparts, and considerable effort has made since that time to develop applications for them based on their unique adsorption, cation-exchange, dehydration-rehydration, and catalytic properties. Natural zeolites (i.e., those found in volcanogenic sedimentary rocks) have been and are being used as building stone, as lightweight aggregate and pozzolans in cements and concretes, as filler in paper, in the take-up of Cs and Sr from nuclear waste and fallout, as soil amendments in agronomy and horticulture, in the removal of ammonia from municipal, industrial, and agricultural waste and drinking waters, as energy exchangers in solar refrigerators, as dietary supplements in animal diets, as consumer deodorizers, in pet litters, in taking up ammonia from animal manures, and as ammonia filters in kidney-dialysis units. From their use in construction during Roman times, to their role as hydroponic (zeoponic) substrate for growing plants on space missions, to their recent success in the healing of cuts and wounds, natural zeolites are now considered to be full-fledged mineral commodities, the use of which promise to expand even more in the future.

  1. Nanocrystalline zeolite beta and zeolite Y as catalysts in used palm oil cracking for the production of biofuel

    Science.gov (United States)

    Taufiqurrahmi, Niken; Mohamed, Abdul Rahman; Bhatia, Subhash

    2011-08-01

    Nanocrystalline zeolites with crystal size smaller than 100 nm are potential replacement for conventional zeolite catalysts due to their unique characteristics and advantages. In this study, the synthesis of nanocrystalline zeolite Y (FAU) and nanocrystalline zeolite beta (BEA) under hydrothermal conditions is reported. The effect of crystal size on the physico-chemical characteristics of the zeolite, Y (FAU), and beta (BEA) is reported. The properties of nanocrystalline zeolites Y and Beta with crystal size around 50 nm are compared with the microcrystalline zeolite Y and microcrystalline zeolite beta, respectively. The performance of the nanocrystalline zeolite as a catalyst was investigated in the cracking of used palm oil for the production of biofuel. The nanocrystalline zeolite catalytic activity was compared with the activity of microcrystalline zeolite in order to study the effect of crystal size on the catalytic activity. Both nanocrystalline zeolites gave better performance in terms of conversion of used palm oil as well as selectivity for the formation of gasoline fraction. The increase in surface area and improved accessibility of the reactant in nanocrystalline zeolites enhanced the cracking activity as well as the desired product selectivity.

  2. Power-constrained supercomputing

    Science.gov (United States)

    Bailey, Peter E.

    As we approach exascale systems, power is turning from an optimization goal to a critical operating constraint. With power bounds imposed by both stakeholders and the limitations of existing infrastructure, achieving practical exascale computing will therefore rely on optimizing performance subject to a power constraint. However, this requirement should not add to the burden of application developers; optimizing the runtime environment given restricted power will primarily be the job of high-performance system software. In this dissertation, we explore this area and develop new techniques that extract maximum performance subject to a particular power constraint. These techniques include a method to find theoretical optimal performance, a runtime system that shifts power in real time to improve performance, and a node-level prediction model for selecting power-efficient operating points. We use a linear programming (LP) formulation to optimize application schedules under various power constraints, where a schedule consists of a DVFS state and number of OpenMP threads for each section of computation between consecutive message passing events. We also provide a more flexible mixed integer-linear (ILP) formulation and show that the resulting schedules closely match schedules from the LP formulation. Across four applications, we use our LP-derived upper bounds to show that current approaches trail optimal, power-constrained performance by up to 41%. This demonstrates limitations of current systems, and our LP formulation provides future optimization approaches with a quantitative optimization target. We also introduce Conductor, a run-time system that intelligently distributes available power to nodes and cores to improve performance. The key techniques used are configuration space exploration and adaptive power balancing. Configuration exploration dynamically selects the optimal thread concurrency level and DVFS state subject to a hardware-enforced power bound

  3. Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

    Science.gov (United States)

    1997-04-01

    An experimental study of sulfur tolerant zeolite platinum catalysts for aormatics hydrogenation. Platinum catalysts supported on Y-zeolite have been prepared and characterized in various ways, including the hydrogenation of toluene in a high pressure...

  4. Reflected stochastic differential equation models for constrained animal movement

    Science.gov (United States)

    Hanks, Ephraim M.; Johnson, Devin S.; Hooten, Mevin B.

    2017-01-01

    Movement for many animal species is constrained in space by barriers such as rivers, shorelines, or impassable cliffs. We develop an approach for modeling animal movement constrained in space by considering a class of constrained stochastic processes, reflected stochastic differential equations. Our approach generalizes existing methods for modeling unconstrained animal movement. We present methods for simulation and inference based on augmenting the constrained movement path with a latent unconstrained path and illustrate this augmentation with a simulation example and an analysis of telemetry data from a Steller sea lion (Eumatopias jubatus) in southeast Alaska.

  5. Zeolite Membranes: Ozone Detemplation, Modeling, and Performance Characterization

    OpenAIRE

    Kuhn, J.

    2009-01-01

    Membrane technology plays an increasingly important role in developing a more sustainable process industry. Zeolites are a novel class of membrane materials with unique properties enabling molecular sieving and affinity based separations. This thesis proposes some new concepts in zeolite membrane synthesis, application, and modeling. The influence of zeolite polarity is assessed and the use of a hydrophobic zeolite membrane for water separation is explored. Ozonication, a novel method for zeo...

  6. Polyphosphates substitution for zeolite to in detergents

    International Nuclear Information System (INIS)

    Restrepo V, Gloria M.; Ocampo G, Aquiles; Saldarriaga M, Carlos

    1996-01-01

    The detergents, as well as the cleaning products, contain active ingredients that are good to increase their efficiency and some of them, as the sodium Tripoli-phosphate (TPF), they have turned out to be noxious for the environment. The zeolites use in the formulation of detergents has grown substantially since they fulfill the same function of the TPF and they have been recommended ecologically as substitutes from these when not being polluting. The objective of this work is to obtain a zeolite with appropriate characteristics for its use in the formulation of detergents, reproducing those of the zeolites used industrially. The zeolite synthesis is studied 4A starting from hydro-gels of different composition, varying the operation conditions and using two raw materials: (sodium meta-silicate, commercial degree and metallic aluminum) and clay type kaolin like silica source and aluminum It is looked for to get a product of beveled cubic morphology, or spherical, with glass size between 1 and 3 microns and that it possesses good capacity of conical exchange. Since the capacity and speed of ionic exchange is influenced by the particle size, time of contact and temperature, experimentation conditions settle down to measure the exchange of ions calcium and magnesium in watery solutions that they simulate the real situation of a laundry process in the country. This way the ability of the zeolite 4A obtained to diminish the concentration of these ions in the laundry waters is evaluated and its possibilities like component in the formulation of detergents non-phosphatates. Of the synthesized zeolites, the best in agreement is chosen with chemical properties as ionic and physical exchange capacity as crystalline, particle size and color, to prepare a detergent in which the polyphosphates is substituted partial and totally for the synthesized zeolite

  7. Molecular Simulation of Adsorption in Zeolites

    Science.gov (United States)

    Bai, Peng

    Zeolites are a class of crystalline nanoporous materials that are widely used as catalysts, sorbents, and ion-exchangers. Zeolites have revolutionized the petroleum industry and have fueled the 20th-century automobile culture, by enabling numerous highly-efficient transformations and separations in oil refineries. They are also posed to play an important role in many processes of biomass conversion. One of the fundamental principles in the field of zeolites involves the understanding and tuning of the selectivity for different guest molecules that results from the wide variety of pore architectures. The primary goal of my dissertation research is to gain such understanding via computer simulations and eventually to reach the level of predictive modeling. The dissertation starts with a brief introduction of the applications of zeolites and computer modeling techniques useful for the study of zeolitic systems. Chapter 2 then describes an effort to improve simulation efficiency, which is essential for many challenging adsorption systems. Chapter 3 studies a model system to demonstrate the applicability and capability of the method used for the majority of this work, configurational-bias Monte Carlo simulations in the Gibbs ensemble (CBMC-GE). After these methodological developments, Chapter 4 and 5 report a systematic parametrization of a new transferable force field for all-silica zeolites, TraPPE-zeo, and a subsequent, relatively ad-hoc extension to cation-exchanged aluminosilicates. The CBMC-GE method and the TraPPE-zeo force field are then combined to investigate some complex adsorption systems, such as linear and branched C6-C 9 alkanes in a hierarchical microporous/mesoporous material (Chapter 6), the multi-component adsorption of aqueous alcohol solutions (Chapter 7) and glucose solutions (Chapter 8). Finally, Chapter 9 describes an endeavor to screen a large number of zeolites with the purpose of finding better materials for two energy-related applications

  8. Selective methane chlorination to methyl chloride by zeolite Y-based catalysts

    Science.gov (United States)

    Joo, Hyeonho; Kim, Daeho; Lim, Kwang Soo; Choi, Yong Nam; Na, Kyungsu

    2018-03-01

    The CH4 chlorination over Y zeolites was investigated to produce CH3Cl in a high yield. Three different catalytic systems based on Y zeolite were tested for enhancement of CH4 conversion and CH3Cl selectivity: (i) HY zeolites in H+-form having various Si/Al ratios, (ii) Pt/HY zeolites supporting Pt metal nanoparticles, (iii) Pt/NaY zeolites in Na+-form supporting Pt metal nanoparticles. The reaction was carried out using the gas mixture of CH4 and Cl2 with the respective flow rates of 15 and 10 mL min-1 at 300-350 °C using a fixed-bed reactor under a continuous gas flow condition (gas hourly space velocity = 3000 mL g-1 h-1). Above the reaction temperature of 300 °C, the CH4 chlorination is spontaneous even in the absence of catalyst, achieving 23.6% of CH4 conversion with 73.4% of CH3Cl selectivity. Under sufficient supplement of thermal energy, Cl2 molecules can be dissociated to two chlorine radicals, which triggered the C-H bond activation of CH4 molecule and thereby various chlorinated methane products (i.e., CH3Cl, CH2Cl2, CHCl3, CCl4) could be produced. When the catalysts were used under the same reaction condition, enhancement in the CH4 conversion was observed. The Pt-free HY zeolite series with varied Si/Al ratios gave around 27% of CH4 conversion, but there was a slight decrease in CH3Cl selectivity with about 64%. Despite the difference in acidity of HY zeolites having different Si/Al ratios, no prominent effect of the Si/Al ratios on the catalytic performance was observed. This suggests that the catalytic contribution of HY zeolites under the present reaction condition is not strong enough to overcome the spontaneous CH4 chlorination. When the Pt/HY zeolite catalysts were used, the CH4 conversion reached further up to 30% but the CH3Cl selectivity decreased to 60%. Such an enhancement of CH4 conversion could be attributed to the strong catalytic activity of HY and Pt/HY zeolite catalysts. However, both catalysts induced the radical cleavage of Cl2

  9. Effect of micronized zeolite addition to lamb concentrate feeds on ...

    African Journals Online (AJOL)

    OEM

    2016-09-21

    Sep 21, 2016 ... Natural zeolites are utilized in a number of industries such as pollution control ... the impact of zeolites on milk quality, an addition of 2.5% of clinoptilolite (zeolite) to goat feeds was demonstrated to ... triglyceride, calcium and phosphorus was carried out with spectrophotometry, and the tests for sodium,.

  10. Zeolites and Zeotypes for Oil and Gas Conversion

    NARCIS (Netherlands)

    Vogt, Eelco T C; Whiting, Gareth T.; Dutta Chowdhury, Abhishek; Weckhuysen, Bert M.

    2015-01-01

    Zeolite-based catalyst materials are widely used in chemical industry. In this chapter, the applications of zeolites and zeotypes in the catalytic conversion of oil and gas are reviewed. After a general introduction to zeolite science and technology, we discuss refinery applications, such as fluid

  11. defluorination of drinking water using surfactant modified zeolites

    African Journals Online (AJOL)

    PUBLICATIONS1

    The unmodified zeolite NaLSX was incapable of adsorbing fluoride ions but the surfactant modified zeolite adsorbed fluoride. The fluoride adsorption capacity of the modified zeolite was. pH dependent and peaked at pH 6.0 – 7.0. INTRODUCTION. Groundwater is often presumed to be fairly safe for consumption compared ...

  12. Influencing the selectivity of zeolite Y for triglycine adsorption

    NARCIS (Netherlands)

    Wijntje, R.; Bosch, H.; Haan, A.B. de; Bussmann, P.J.T.

    2007-01-01

    In prior work we studied the adsorption of triglycine on zeolite Y under reference conditions. This study aims to solve the question of which adsorbent properties and process conditions influence the adsorption triglycine from an aqueous solution by zeolite Y. Relevant zeolite parameters to study

  13. Exploring Constrained Creative Communication

    DEFF Research Database (Denmark)

    Sørensen, Jannick Kirk

    2017-01-01

    Creative collaboration via online tools offers a less ‘media rich’ exchange of information between participants than face-to-face collaboration. The participants’ freedom to communicate is restricted in means of communication, and rectified in terms of possibilities offered in the interface. How do...... these constrains influence the creative process and the outcome? In order to isolate the communication problem from the interface- and technology problem, we examine via a design game the creative communication on an open-ended task in a highly constrained setting, a design game. Via an experiment the relation...... between communicative constrains and participants’ perception of dialogue and creativity is examined. Four batches of students preparing for forming semester project groups were conducted and documented. Students were asked to create an unspecified object without any exchange of communication except...

  14. Molecular simulations and experimental studies of zeolites

    Science.gov (United States)

    Moloy, Eric C.

    Zeolites are microporous aluminosilicate tetrahedral framework materials that have symmetric cages and channels with open-diameters between 0.2 and 2.0 nm. Zeolites are used extensively in the petrochemical industries for both their microporosity and their catalytic properties. The role of water is paramount to the formation, structure, and stability of these materials. Zeolites frequently have extra-framework cations, and as a result, are important ion-exchange materials. Zeolites also play important roles as molecular sieves and catalysts. For all that is known about zeolites, much remains a mystery. How, for example, can the well established metastability of these structures be explained? What is the role of water with respect to the formation, stabilization, and dynamical properties? This dissertation addresses these questions mainly from a modeling perspective, but also with some experimental work as well. The first discussion addresses a special class of zeolites: pure-silica zeolites. Experimental enthalpy of formation data are combined with molecular modeling to address zeolitic metastability. Molecular modeling is used to calculate internal surface areas, and a linear relationship between formation enthalpy and internal surface areas is clearly established, producing an internal surface energy of approximately 93 mJ/m2. Nitrate bearing sodalite and cancrinite have formed under the caustic chemical conditions of some nuclear waste processing centers in the United States. These phases have fouled expensive process equipment, and are the primary constituents of the resilient heels in the bottom of storage tanks. Molecular modeling, including molecular mechanics, molecular dynamics, and density functional theory, is used to simulate these materials with respect to structure and dynamical properties. Some new, very interesting results are extracted from the simulation of anhydrous Na6[Si6Al 6O24] sodalite---most importantly, the identification of two distinct

  15. Characterization of Zeolite in Zeolite-Geopolymer Hybrid Bulk Materials Derived from Kaolinitic Clays.

    Science.gov (United States)

    Takeda, Hayami; Hashimoto, Shinobu; Yokoyama, Hiroaki; Honda, Sawao; Iwamoto, Yuji

    2013-05-06

    Zeolite-geopolymer hybrid materials have been formed when kaolin was used as a starting material. Their characteristics are of interest because they can have a wide pore size distribution with micro- and meso-pores due to the zeolite and geopolymer, respectively. In this study, Zeolite-geopolymer hybrid bulk materials were fabricated using four kinds of kaolinitic clays (a halloysite and three kinds of kaolinite). The kaolinitic clays were first calcined at 700 °C for 3 h to transform into the amorphous aluminosilicate phases. Alkali-activation treatment of the metakaolin yielded bulk materials with different amounts and types of zeolite and different compressive strength. This study investigated the effects of the initial kaolinitic clays on the amount and types of zeolite in the resultant geopolymers as well as the strength of the bulk materials. The kaolinitic clays and their metakaolin were characterized by XRD analysis, chemical composition, crystallite size, 29 Si and 27 Al MAS NMR analysis, and specific surface area measurements. The correlation between the amount of zeolite formed and the compressive strength of the resultant hybrid bulk materials, previously reported by other researchers was not positively observed. In the studied systems, the effects of Si/Al and crystalline size were observed. When the atomic ratio of Si/Al in the starting kaolinitic clays increased, the compressive strength of the hybrid bulk materials increased. The crystallite size of the zeolite in the hybrid bulk materials increased with decreasing compressive strength of the hybrid bulk materials.

  16. Deuterium exchange with the surface hydrogen of zeolite catalysts. 7. Nickel-containing zeolites

    International Nuclear Information System (INIS)

    Minachev, Kh.M.; Dmitriev, R.V.; Penchev, V.; Kanazirev, V.; Minchev, Kh.; Kasimov, Ch.K.

    1982-01-01

    An in-depth study of heteromolecular isotopic hydrogen exchange (HIHE) in Ni zeolites was undertaken with a view to measuring surface OH group concentrations and determining effectiveness of Ni, on the one hand, and Pd and Pt, on the other, in promoting chemical reactions. Here the degree of metal dispersion in the Ni zeolite was characterized through H 2 chemisorption and thermosorption data. A study was made of the action of these zeolites in catalyzing the disproportionation of toluene. The data obtained here have given an understanding of the effect of the metal, the OH-group concentration, and the mutual arrangement of OH groups and Ni atoms on catalyzed toluene reactions. Results indicated that HIHE occurs on reduced nickel-containing zeolite catalysts at temperatures in excess of 100 0 C, and is limited by the rate of transport of activated hydrogen from the metal particles on the support surface. High-temperature oxidation-reduction of the nickel-containing zeolite-leads to the formation of coarse nickel crystals on the external zeolite crystal faces. Also, the reduced NiCaNaY zeolites show high catalytic activity in the toluene disproportionation only when the nickel has been introduced through ion exchange. Both isotopic exchange and toluene disproportionation are promoted when the nickel particles and OH groups are in close proximity

  17. Effect of zeolites on chitosan/zeolite hybrid membranes for direct methanol fuel cell

    Science.gov (United States)

    Wang, Jingtao; Zheng, Xiaohong; Wu, Hong; Zheng, Bin; Jiang, Zhongyi; Hao, Xiaopeng; Wang, Baoyi

    Zeolites including 3A, 4A, 5A, 13X, mordenite, and HZSM-5 were incorporated into chitosan (CS) matrix to fabricate the hybrid membranes for direct methanol fuel cell (DMFC). Due to the presence of hydrogen bonds between CS and zeolite, the hybrid membranes displayed desirable thermal and mechanical stabilities. Through free volume characteristics analysis by positron annihilation lifetime spectroscopy (PALS) technique, it was found that incorporation of hydrophilic zeolites would increase the free volume cavity size whereas incorporation of hydrophobic zeolites would decrease the free volume cavity size. Through the investigations on water/methanol uptake, swelling, and methanol permeability, it was found that the membrane performance was highly dependent on the zeolite particle and pore size, content, and hydrophilic/hydrophobic nature. Based on the solution-diffusion mechanism, it was found that incorporation of hydrophobic zeolites increased the diffusion resistance of methanol and consequently decreased the methanol permeability, whereas incorporation of hydrophilic zeolites decreased the diffusion resistance of methanol and consequently increased the methanol permeability. Moreover, under the identical conditions, all the as-prepared membranes exhibited much lower methanol permeability than Nafion ® 117 while the proton conductivity of the membranes remained high enough for DMFC applications.

  18. Environmental application of modified natural zeolites

    International Nuclear Information System (INIS)

    Nikashina, V.A.; Myasoedov, B.F.

    1998-01-01

    The following techniques were used for the chemical modification of the natural zeolites: (1) treatment of natural zeolites with organic substances. Examples of applications of these sorbents to the decontamination and disinfection of solutions of different composition and surface waters are presented. (2) Treatment of the natural zeolites with a inorganic substances. (2.1) The clinoptilolite-rich tuffs were treated with a hot suspensions of freshly precipitated magnetite. This leads to the preparation of sorbents possessing magnetic properties. The radionuclides and heavy metals recovery from soils and silts was investigated using different soil and ferromagnetic zeolite weights ratios and contact times. Different soils and sorbent of varying capacities were used for these investigations. As example, the recovery 137 Cs and 85 Sr from soils of different nature is presented. (2.2) Treatment of natural zeolites with Fe-containing solutions of Fe-containing natural waters. The filtration of these solutions through clinoptilolite-rich tuffs makes leads to preparation of materials possessing high selectivity to PO 4 3- ions. The properties of these sorbents can be utilized for the PO 4 3+ decontamination of waters (e.g. waste waters) and for the subsequent use of these materials in agriculture as fertilizers.(author)

  19. Synthesis and Characterization of Zeolite Na−Y and Its Conversion to the Solid Acid Zeolite H−Y

    DEFF Research Database (Denmark)

    Warner, Terence Edwin; Galsgaard Klokker, Mads; Nielsen, Ulla Gro

    2017-01-01

    various preparative strategies with the students, such as the three-stage procedure described here. Stage I concerns the hydrothermal synthesis of zeolite Na−Y, followed by ion-exchange with an ammonium acetate solution to form zeolite NH4−Y, and the latter is subsequently converted to zeolite H...

  20. Constrained systems described by Nambu mechanics

    International Nuclear Information System (INIS)

    Lassig, C.C.; Joshi, G.C.

    1996-01-01

    Using the framework of Nambu's generalised mechanics, we obtain a new description of constrained Hamiltonian dynamics, involving the introduction of another degree of freedom in phase space, and the necessity of defining the action integral on a world sheet. We also discuss the problem of quantizing Nambu mechanics. (authors). 5 refs

  1. Stacking technology for a space constrained microsystem

    DEFF Research Database (Denmark)

    Heschel, Matthias; Kuhmann, Jochen Friedrich; Bouwstra, Siebe

    1998-01-01

    In this paper we present a stacking technology for an integrated packaging of an intelligent transducer which is formed by a micromachined silicon transducer and an integrated circuit chip. Transducer and circuitry are stacked on top of each other with an intermediate chip in between. The bonding...

  2. Natural zeolite polypropylene composite film preparation and characterization

    OpenAIRE

    Özmıhçı, Filiz; Balköse, Devrim; Ülkü, Semra

    2001-01-01

    In this research, the preparation and characterization of polypropylene (PP) and natural zeolite composites were studied. Natural zeolite mined in Gördes, Turkey was used as an alternative filler to CaCO3. Films were prepared by the extrusion of PP, and surface-modified zeolite was made by polyethylene glycol 4000 with 2-4% zeolite. Zeolite-filled composites had densities between 0.73 and 0.83 g/cm3 and had void fractions of 0.07-0.20. Although the permeability of water vapour through 2% zeol...

  3. Reorientational dynamics of water confined in zeolites.

    Science.gov (United States)

    Fogarty, Aoife C; Coudert, François-Xavier; Boutin, Anne; Laage, Damien

    2014-02-24

    We present a detailed molecular-dynamics study of water reorientation and hydrogen-bond dynamics in a strong confinement situation, within the narrow pores of an all-silica Linde type A (LTA) zeolite. Two water loadings of the zeolite are compared with the bulk case. Water dynamics are retarded in this extreme hydrophobic confinement and the slowdown is more pronounced at higher water loading. We show that water reorientation proceeds mainly by large-amplitude angular jumps, whose mechanism is similar to that determined in the bulk. The slowdown upon hydrophobic confinement arises predominantly from an excluded-volume effect on the large fraction of water molecules lying at the interface with the zeolite matrix, with an additional minor contribution coming from a structuring effect induced by the confinement. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Cupric natural zeolites as microbic ides

    International Nuclear Information System (INIS)

    Contreras A, D.; Olguin G, M. T.; Alcantara D, D.; Burrola A, C.

    2009-01-01

    The Escherichia coli and the Candida albicans are considered contamination indicators for what these organisms reflect the water quality. The natural zeolites by their characteristics and properties, they could incorporate to a waters treatment system, as ion exchange, adsorbents and/or microbiocid agents, representing an alternative method of low cost. Inside this investigation work was found that depending on the microorganism type, it varies the quantity of cupric zeolite that is required to carry out the water disinfection, being great for the case of yeasts than the bacteria s. In addition to that marked differences are presented in the required time to reach this process. The characterization of the natural zeolite material, sodium and cupric, was realized by means of scanning electron microscopy, determining the elementary composition (Energy Dispersive Spectroscopy) of each one of them, and by X-ray diffraction. (Author)

  5. Minimal constrained supergravity

    Directory of Open Access Journals (Sweden)

    N. Cribiori

    2017-01-01

    Full Text Available We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  6. Chemical imaging of catalyst deactivation during the conversion of renewables at the single particle level: etherification of biomass-based polyols with alkenes over H-Beta zeolites.

    Science.gov (United States)

    Parvulescu, Andrei N; Mores, Davide; Stavitski, Eli; Teodorescu, Cristian M; Bruijnincx, Pieter C A; Gebbink, Robertus J M Klein; Weckhuysen, Bert M

    2010-08-04

    The etherification of biomass-based alcohols with various linear alpha-olefins under solvent-free conditions was followed in a space- and time-resolved manner on 9 microm large H-Beta zeolite crystals by confocal fluorescence microscopy. This allowed us to visualize the interaction with the substrate and distribution of the coke products into the catalyst at the level of an individual zeolite crystal during the etherification process. The spectroscopic information obtained on the micrometer-scale zeolite was in line with the results obtained with bulk characterization techniques and further confirmed by the catalytic results obtained both for micrometer-scale and nanoscale zeolites. This allowed us to explain the influence of the substrate type (glycerol, glycols, and alkenes) and zeolite properties (Si/Al ratio and particle size) on the etherification activity. The etherification of the biomass-based alcohols takes place mainly on the external surface of the zeolite particles. The gradual blockage of the external surface of the zeolite results in a partial or total loss of etherification activity. The deactivation could be attributed to olefin oligomerization. The high conversions obtained in the etherification of 1,2-propylene glycol with long linear alkenes (up to 80%) and the pronounced deactivation of the zeolite observed in the etherification of glycerol with long linear alkenes (max. 20% conversion) were explained by the spectroscopic measurements and is due to differences in the adsorption, i.e., in the center of the zeolite particle for glycerol and on the external surface in the case of glycols.

  7. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550 °C, 5 h) and this material has excellent performance as an antibacterial agent after silver ions loading. - Highlights: • Thermal treatment was used to regenerate surfactant modified zeolite. • The regenerated NaY zeolite formed was added with different silver loadings. • Regenerated AgY zeolite was tested for antibacterial activity on E. coli and S. aureus. • The antibacterial activity increased with increased of the amount of silver loadings. • The zeolite structure did not change with thermal and modification

  8. Adsorption Cooling System Using Metal-Impregnated Zeolite-4A

    Directory of Open Access Journals (Sweden)

    Somsuk Trisupakitti

    2016-01-01

    Full Text Available The adsorption cooling systems have been developed to replace vapor compression due to their benefits of being environmentally friendly and energy saving. We prepared zeolite-4A and experimental cooling performance test of zeolite-water adsorption system. The adsorption cooling test-rig includes adsorber, evaporator, and condenser which perform in vacuum atmosphere. The maximum and minimum water adsorption capacity of different zeolites and COP were used to assess the performance of the adsorption cooling system. We found that loading zeolite-4A with higher levels of silver and copper increased COP. The Cu6%/zeolite-4A had the highest COP at 0.56 while COP of zeolite-4A alone was 0.38. Calculating the acceleration rate of zeolite-4A when adding 6% of copper would accelerate the COP at 46%.

  9. AKTIVASI ZEOLIT ALAM SEBAGAI ADSORBEN PADA ALAT PENGERING BERSUHU RENDAH

    Directory of Open Access Journals (Sweden)

    Laeli Kurniasari

    2012-04-01

    Full Text Available ACTIVATION OF NATURAL ZEOLITE AS AN ADSORBENT FOR LOW TEMPERATURE DRYING SYSTEM. Drying is one process which is used in many industries, especially in food product. The process usually still has low energy efficiency and can make food deterioration because of the usage of high temperature. One alternative in drying technology is the use of zeolite as a water vapor adsorbent. This kind of drying method make it possible to operate in lower temperature, hence it will be suitable for heat sensitive product. Natural zeolit can be one promising adsorbent since it is spreadly abundant in Indonesia. Natural zeolite must be activated first before used, in order to get zeolite with high adsorption capacity. Activation process in natural zeolite will change the Si/Al ratio, polarity, and affinity of zeolite toward water vapor and also increase the porosity. Activation of natural zeolite can be done with two methods, chemical activation use NaOH and physical activation use heat. In the activation using NaOH, natural zeolite is immersed with NaOH solution 0.5-2N in 2 hour with temperature range 60-900C. The process is continued with the drying of zeolite in oven with 1100C for 4 hours. While in heat treatment, zeolit is heated into 200-5000C in furnace for 2-5 hours. SEM analysis is used to compare the change in zeolite morphology before and after each treatment, while to know the adsorption capacity of zeolite, the analyses were done in many temperature and relative humidity. Result gives the best condition in NaOH activation is NaOH 1N and temperature 700C, with water vapor loading is 0.171 gr/gr adsorbent. In heat treatment, the best condition is 3000C and 3 hours with loading 0.137 gr water vapor/gr adsorbent.  Pengeringan merupakan salah satu proses yang banyak digunakan pada produk pangan. Proses ini umumnya menyebabkan kerusakan pada bahan pangan, disamping masih rendahnya efisiensi energi. Salah satu alternatif pada proses pengeringan yaitu

  10. Development of spent salt treatment technology by zeolite column system. Performance evaluation of zeolite column

    International Nuclear Information System (INIS)

    Miura, Hidenori; Uozumi, Koichi

    2009-01-01

    At electrorefining process, fission products(FPs) accumulate in molten salt. To avoid influence on heating control by decay heat and enlargement of FP amount in the recovered fuel, FP elements must be removed from the spent salt of the electrorefining process. For the removal of the FPs from the spent salt, we are investigating the availability of zeolite column system. For obtaining the basic data of the column system, such as flow property and ion-exchange performance while high temperature molten salt is passing through the column, and experimental apparatus equipped with fraction collector was developed. By using this apparatus, following results were obtained. 1) We cleared up the flow parameter of column system with zeolite powder, such as flow rate control by argon pressure. 2) Zeolite 4A in the column can absorb cesium that is one of the FP elements in molten salt. From these results, we got perspective on availability of the zeolite column system. (author)

  11. Structural reconstruction: a milestone in the hydrothermal synthesis of highly active Sn-Beta zeolites.

    Science.gov (United States)

    Zhu, Zhiguo; Xu, Hao; Jiang, Jingang; Wu, Haihong; Wu, Peng

    2017-11-21

    A novel structural reconstruction strategy is proposed to prepare an active Sn-Beta catalyst with high Sn contents and a hydrophobic nature. Compared with post-synthesized Sn-Beta and state-of-the-art classic fluoride-mediated Sn-Beta-F, this Sn-Beta zeolite exhibits unparalleled active site-based turnover frequency for desirable products and in particular catalyst weight-based space-time-yields in various redox reactions of ketones.

  12. Ultratrace Measurement of Acetone from Skin Using Zeolite: Toward Development of a Wearable Monitor of Fat Metabolism.

    Science.gov (United States)

    Yamada, Yuki; Hiyama, Satoshi; Toyooka, Tsuguyoshi; Takeuchi, Shoji; Itabashi, Keiji; Okubo, Tatsuya; Tabata, Hitoshi

    2015-08-04

    Analysis of gases emitted from human skin and contained in human breath has received increasing attention in recent years for noninvasive clinical diagnoses and health checkups. Acetone emitted from human skin (skin acetone) should be a good indicator of fat metabolism, which is associated with diet and exercise. However, skin acetone is an analytically challenging target because it is emitted in very low concentrations. In the present study, zeolite was investigated for concentrating skin acetone for subsequent semiconductor-based analysis. The adsorption and desorption characteristics of five zeolites with different structures and those hydrophobicities were compared. A hydrophobic zeolite with relatively large pores (approximately 1.6 times larger than the acetone molecule diameter) was the best concentrator of skin acetone among the zeolites tested. The concentrator developed using zeolite was applied in a semiconductor-based gas sensor in a simulated mobile environment where the closed space was frequently collapsed to reflect the twisting and elastic movement of skin that would be encountered in a wearable device. These results could be used to develop a wearable analyzer for skin acetone, which would be a powerful tool for preventing and alleviating lifestyle-related diseases.

  13. TITANIUM OXIDE DISPERSED ON NATURAL ZEOLITE (TiO2/ZEOLITE AND ITS APPLICATION FOR CONGO RED PHOTODEGRADATION

    Directory of Open Access Journals (Sweden)

    Is Fatimah

    2010-06-01

    Full Text Available The utilization of TiO2 dispersed on natural zeolite (TiO2/Zeolite for degradation of Congo Red photocatlytically has been performed. The TiO2/Zeolite was prepared by mechanically mixing of 100 g of natural zeolite, which it has been heated at 400oC, with TiO2 powder, the final weight ratio of the mixture was 5% (w/w. The mixture was then calcined at 400oC for 6 hours. The calcined product was characterized using x-ray diffractometry, x-ray fluorescence analysis and gas sorption analysis methods to determine its physicochemical properties changes caused by mixing and calcination. Investigation of Congo Red photodegradation using TiO2/Zeolite was carried out by mixing 25 mL 10-4 M solution of Congo Red with 25 mg of TiO2/Zeolite and irradiating the suspention with UV-light of 350 nm for 10, 20, 30, 40, 50 and 60 minutes, respectively. The characterization results showed that dispertion of TiO2 on zeolite resulted in the increasing of titanium concentration on TiO2/Zeolite. The concentration of Ti on natural zeolite was found to be 0.15%(w/w, meanwhile on TiO2/Zeolite was 2.29% (w/w. From X-ray diffractometry analysis result no information was found that TiO2 was dipersed on natural zeolite. It was caused by overlapping of the reflections of zeolite with reflections of TiO2. On the otherhand, the gas sorption analysis result exhibited that the dispersion of TiO2 on zeolite resulted in the decreasing of total pore volume as well as specific surface area of the natural zeolite. The specific surface areas of natural zeolite and TiO2/Zeolite were 21.98 and 16.74 m2/g, respectively, meanwhile the total pore volumes of natural zeolite and TiO2/Zeolite were 20.10x10-3 and 13.47x10-3 mL/g. The simple kinetic of photodegradation of Congo Red exhibited that the rate of degradation followed a first order kinetic and the reaction rate constant was 0.0017 minute-1.   Keywords: natural zeolite, TiO2, photodegradation, Congo Red

  14. Classification Constrained Dimensionality Reduction

    OpenAIRE

    Raich, Raviv; Costa, Jose A.; Damelin, Steven B.; Hero III, Alfred O.

    2008-01-01

    Dimensionality reduction is a topic of recent interest. In this paper, we present the classification constrained dimensionality reduction (CCDR) algorithm to account for label information. The algorithm can account for multiple classes as well as the semi-supervised setting. We present an out-of-sample expressions for both labeled and unlabeled data. For unlabeled data, we introduce a method of embedding a new point as preprocessing to a classifier. For labeled data, we introduce a method tha...

  15. Crystallization and melting behavior of isotactic polypropylene composites filled by zeolite supported {beta}-nucleator

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Juan [Materials Science Institute, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Key Laboratory of Polymeric Composites and Functional Materials, the Ministry of Education, Key Laboratory of Designed Synthesis and Application of Polymer Material of Guangdong Province, Guangzhou 510275 (China); Li, Gu, E-mail: ceslg@mail.sysu.edu.cn [Key Laboratory of Polymeric Composites and Functional Materials, the Ministry of Education, Key Laboratory of Designed Synthesis and Application of Polymer Material of Guangdong Province, Guangzhou 510275 (China); Tan, Nanshu [Key Laboratory of Polymeric Composites and Functional Materials, the Ministry of Education, Key Laboratory of Designed Synthesis and Application of Polymer Material of Guangdong Province, Guangzhou 510275 (China); Ding, Qian [Materials Science Institute, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Key Laboratory of Polymeric Composites and Functional Materials, the Ministry of Education, Key Laboratory of Designed Synthesis and Application of Polymer Material of Guangdong Province, Guangzhou 510275 (China); Mai, Kancheng, E-mail: cesmkc@mail.sysu.edu.cn [Materials Science Institute, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Key Laboratory of Polymeric Composites and Functional Materials, the Ministry of Education, Key Laboratory of Designed Synthesis and Application of Polymer Material of Guangdong Province, Guangzhou 510275 (China)

    2012-10-20

    Highlights: Black-Right-Pointing-Pointer The supported calcium pimelate {beta}-zeolite was prepared. Black-Right-Pointing-Pointer The {beta}-nucleation of zeolite was enhanced dramatically through reaction. Black-Right-Pointing-Pointer High {beta}-phase content iPP composites were obtained by introducing the {beta}-zeolite into iPP. - Abstract: In order to prepare the zeolite filled {beta}-iPP composites, the calcium pimelate as {beta}-nucleator supported on the surface of zeolite ({beta}-zeolite) was prepared by the interaction between calcified zeolite and pimelic acid. The {beta}-nucleation, crystallization behavior and melting characteristic of zeolite, calcified zeolite and {beta}-zeolite filled iPP composites were investigated by differential scanning calorimetry and wide-angle X-ray diffractometer. The results indicated that addition of the zeolite and calcified zeolite as well as {beta}-zeolite increased the crystallization temperature of iPP. The zeolite and calcified zeolite filled iPP composites mainly crystallized in the {alpha}-crystal form and the strong {beta}-heterogeneous nucleation of {beta}-zeolite results in the formation of only {beta}-crystal in {beta}-zeolite filled iPP composites. The zeolite filled {beta}-iPP composites with high {beta}-crystal contents (above 0.90) can be easily obtained by adding {beta}-zeolite into iPP matrix.

  16. Automated Precision Maneuvering and Landing in Extreme and Constrained Environments

    Data.gov (United States)

    National Aeronautics and Space Administration — Autonomous, precise maneuvering and landing in extreme and constrained environments is a key enabler for future NASA missions. Missions to map the interior of a...

  17. Two-dimensional zeolites: dream or reality?

    Czech Academy of Sciences Publication Activity Database

    Roth, W. J.; Čejka, Jiří

    2011-01-01

    Roč. 1, č. 1 (2011), s. 43-53 ISSN 2044-4753 R&D Projects: GA AV ČR KAN100400701; GA ČR GA104/09/0561; GA ČR GA203/08/0604 Institutional research plan: CEZ:AV0Z40400503 Keywords : catalysis * physical chemistry * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry

  18. Zeolite from fly ash: synthesis and characterization

    Indian Academy of Sciences (India)

    Unknown

    brought the success in obtaining Na–A zeolite also. Lin and Hsi (1995) extensively investigated effects of ... the reaction parameters to obtain best quality product. They carried out experiments in open as well as in .... and data files compiled in the book by Szostak (1976). The diffractograms show that the original crystalline ...

  19. Extreme Flexibility in a Zeolitic Imidazolate Framework

    DEFF Research Database (Denmark)

    Wharmby, M.T.; Henke, S.; Bennett, T.D.

    2015-01-01

    Desolvated zeolitic imidazolate framework ZIF-4(Zn) undergoes a discontinuous porous to dense phase transition on cooling through 140 K, with a 23% contraction in unit cell volume. The structure of the non-porous, low temperature phase was determined from synchrotron X-ray powder diffraction data...

  20. Ultrasound-assisted dealumination of zeolite Y

    Indian Academy of Sciences (India)

    We demonstrate a new procedure for dealumination of zeolite Y. The method employs a 28 KHz ultrasound bath and an ethanolic acetylacetone solution. Acetylacetone was used as chelating agent and ultrasound irradiation was used as extraction intensifier. Four types of samples, as-synthesized, ammoniumexchanged, ...

  1. Zeolites Promoting Quinoline Synthesis via Friedlander Reaction

    Czech Academy of Sciences Publication Activity Database

    López-Sanz, J.; Pérez-Mayoral, E.; Vitvarová, Dana; Martín-Aranda, R. M.; López-Peinado, A. J.

    2010-01-01

    Roč. 53, 19-20 (2010), s. 1430-1437 ISSN 1022-5528 R&D Projects: GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40400503 Keywords : heterogeneous catalysis * zeolites * quinolines Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.359, year: 2010

  2. Ultrasound-assisted dealumination of zeolite Y

    Indian Academy of Sciences (India)

    Higher dealumination was observed for those samples subjected to both ultrasound irradiation and acetylacetone extraction. Keywords. Microporous; zeolite Y; dealumination; ultrasound irradiation; extraction. 1. ..... ture has also been claimed while ultrasound waves were used for the extraction of contaminants in food and.

  3. Selective synthesis of FAU-type zeolites

    Science.gov (United States)

    Garcia, Gustavo; Cabrera, Saúl; Hedlund, Jonas; Mouzon, Johanne

    2018-05-01

    In the present work, parameters influencing the selectivity of the synthesis of FAU-zeolites from diatomite were studied. The final products after varying synthesis time were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and gas adsorption. It was found that high concentrations of NaCl could completely inhibit the formation of zeolite P, which otherwise usually forms as soon as maximum FAU crystallinity is reached. In the presence of NaCl, the FAU crystals were stable for extended time after completed crystallization of FAU before formation of sodalite. It was also found that addition of NaCl barely changed the crystallization kinetics of FAU zeolite and only reduced the final FAU particle size and SiO2/Al2O3 ratio slightly. Other salts containing either Na or Cl were also investigated. Our results suggest that there is a synergistic effect between Na+ and Cl-. This is attributed to the formation of (Na4Cl)3+ clusters that stabilize the sodalite cages. This new finding may be used to increase the selectivity of syntheses leading to FAU-zeolites and avoid the formation of undesirable by-products, especially if impure natural sources of aluminosilica are used.

  4. Multicomponent liquid ion exchange with chabazite zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, S.M.; Arnold, W.D. Jr.; Byers, C.W.

    1993-10-01

    In spite of the increasing commercial use of zeolites for binary and multicomponent sorption, the understanding of the basic mass-transfer processes associated with multicomponent zeolite ion-exchange systems is quite limited. This study was undertaken to evaluate Na-Ca-Mg-Cs-Sr ion exchange from an aqueous solution using a chabazite zeolite. Mass-transfer coefficients and equilibrium equations were determined from experimental batch-reactor data for single and multicomponent systems. The Langmuir isotherm was used to represent the equilibrium relationship for binary systems, and a modified Dubinin-Polyani model was used for the multicomponent systems. The experimental data indicate that diffusion through the microporous zeolite crystals is the primary diffusional resistance. Macropore diffusion also significantly contributes to the mass-transfer resistance. Various mass-transfer models were compared to the experimental data to determine mass-transfer coefficients. Effective diffusivities were obtained which accurately predicted experimental data using a variety of models. Only the model which accounts for micropore and macropore diffusion occurring in series accurately predicted multicomponent data using single-component diffusivities. Liquid and surface diffusion both contribute to macropore diffusion. Surface and micropore diffusivities were determined to be concentration dependent.

  5. UTL zeolite and the way beyond

    Czech Academy of Sciences Publication Activity Database

    Shvets, O. V.; Nachtigall, P.; Roth, Wieslaw Jerzy; Čejka, Jiří

    2013-01-01

    Roč. 182, DEC 2013 (2013), s. 229-238 ISSN 1387-1811 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : zeolite UTL * synthesis * hydrolysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.209, year: 2013

  6. Dispersion enhanced metal/zeolite catalysts

    Science.gov (United States)

    Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

    1987-01-01

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  7. Utilization of Zeolites in environmentally protection

    Energy Technology Data Exchange (ETDEWEB)

    Kallo, D. [Hungarian Academy of Sciences, Chemical Research Center, Institute of Chemistry, Budapest (Hungary)

    2000-07-01

    It has been attempted to present the most important fields of natural zeolite applications in environmental protection. Realized and approved utilizations were demonstrated inciting the reader to take these materials into consideration for solution of similar problems. The outlined properties can be used for other purposes not discussed in this review. They can be applied, e.g., in fish farming, transportation of living fishes when simultaneous ammonium and carbon dioxide removals is required: ammonium is exchanged for calcium present in the zeolite and CO{sub 2} is then precipitated in the form of CaCO{sub 3}; in treatment of diluted manure when undesired organics can be fixed and bactericide effects can be attained. Natural zeolites are used, therefore, as deodorant of litter of dogs or cats. Small amounts of metal cations, e.g., Cu{sup 2+}, Ag{sup +} or Zn{sup 2+}, introduced by ion exchange may disinfect contacting water. Due to water adsorption and desorption capability natural zeolite as construction materials exert some conditioning effect without any mechanical accessory. It seems likely the human ingenuity will continue to discover new applications in the future.

  8. Synthesis of Diphenylamine Catalyzed by Zeolites

    Czech Academy of Sciences Publication Activity Database

    Hronec, M.; Cvengrošová, Z.; Čejka, Jiří

    2003-01-01

    Roč. 255, - (2003), s. 197-202 ISSN 0926-860X Institutional research plan: CEZ:AV0Z4040901 Keywords : zeolites beta * bentonite * Bronsted site Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.825, year: 2003

  9. Detergents - Zeolites and Enzymes Excel Cleaning Power

    Indian Academy of Sciences (India)

    Presently used detergent formulations generally consist of surfactants, builder and cobuilder, bleaching agents, addi- tives for secondary benefits and enzymes. Zeolites are basically hydrated crystalline aluminium silicates which function as ion exchangers and make the water soft by removing calcium, magnesium and ...

  10. Ultrasound-assisted dealumination of zeolite Y

    Indian Academy of Sciences (India)

    Higher dealumination was observed for those samples subjected to both ultrasound irradiation and acetylacetone extraction ... lite was prepared upon conventional ion-exchange treat- ment using an aqueous solution of 0.4 M NH4Cl at 25. ◦. C ... form of the zeolite to acidic one, it was heated in a muf- fle furnace at rate of 10.

  11. Factors affecting drug adsorption on beta zeolites.

    Science.gov (United States)

    Pasti, Luisa; Sarti, Elena; Cavazzini, Alberto; Marchetti, Nicola; Dondi, Francesco; Martucci, Annalisa

    2013-05-01

    The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO2/Al2O3 ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X-ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Transport through zeolite filled polymeric membranes

    NARCIS (Netherlands)

    Boom, J.P.; Boom, J.P.; Punt, Ineke G.M.; Zwijnenberg, Harmen Jan; Bargeman, D.; de Boer, R.; Smolders, C.A.; Bargeman, D.; Strathmann, H.; Smolders, C.A.

    1998-01-01

    In this paper the effect of zeolite particles incorporated in rubbery polymers on the pervaporation properties of membranes made from these polymers is discussed. Pervaporation of methanol/toluene mixtures was carried out with membranes prepared from the toluene selective polymer EPDM and the

  13. MERCURY SEPARATION FROM POLLUTANT WATER USING ZEOLITES

    Science.gov (United States)

    Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water has been examined at room temperature. Experiments have...

  14. Environmental application of russian natural zeolites

    International Nuclear Information System (INIS)

    Fursenko, B.

    1998-01-01

    There are more than 70 deposits and localities of zeolite-containing rocks (ZCR) in Russia. Total resources of relatively rich (more than 40% of zeolites) rocks are estimated as 3.8 billion tons. The main Russian deposits are located in Siberia and Far East. A number of traditional ways of ZCR utilization for environmental protection have been developed in Russia during last two decades, when a few governmental scientific programs were in operation. These were: (1) waste water treatment (galvanic waste, oil-product pollution, municipal waste water, radioactive pollution); (2) drinking water preparation (municipal and individual filters, coagulation method, lemonade production); (3) gas drying and purification (natural gas drying, stack-gas cleanup, oxygen enriched air production). Growing interest was attracted to zeolites due to their potential utilization in the nuclear waste treatment, re-cultivation of technically polluted territories and especially after they were used for localization of the radioactive accidents on the atomic power stations (Three Mile Island, U.S.A. in 1981 and Chernobyl, USSR in 1986). Structure, ion-exchange capacity and phase transformations of the zeolites are discussed

  15. Constrained CPn models

    International Nuclear Information System (INIS)

    Latorre, J.I.; Luetken, C.A.

    1988-11-01

    We construct a large new class of two dimensional sigma models with Kaehler target spaces which are algebraic manifolds realized as complete interactions in weighted CP n spaces. They are N=2 superconformally symmetric and particular choices of constraints give Calabi-Yau target spaces which are nontrivial string vacua. (orig.)

  16. In-situ application of Ultrasonic Pulse Velocity measurements to determine the degree of zeolitic alteration of ignimbrites

    Science.gov (United States)

    Evren Çubukçu, H.; Yurdakul, Yasin; Erkut, Volkan; Akkaş, Efe; Akın, Lütfiye; Ulusoy, İnan; Şen, Erdal

    2016-04-01

    The velocity of P-waves passing through a rock body is strongly dependent on the petrographical properties such as texture, crystallinity, porosity and fracture network. For this reason, the measurement of ultrasonic pulse velocities (UPV) has been widely used in various applications interested in mechanical properties of solid rock bodies. An ignimbrite is a deposit of pyroclastic density current originating from an explosive volcanic eruption and comprises of vitric volcanic ash, free crystals, juvenile magma fragments (pumice) and accidental xenoliths. The complex nature of the componentry of ignimbrites also exhibits spatial variation depending on the location of deposition. Furthermore, both syn- and post-depositional processes (i.e. welding, alteration etc.) may have drastic impact on the mechanical characteristics of the ignimbrites. Alteration can be defined as the devitrification and the crystallization of vitric components and the transformation of pre-existing minerals of the ignimbrite into new minerals under changing thermodynamic conditions. In this context, zeolitization is an alteration process in which metastable (vitric) components of an ignimbrite body are replaced by zeolite group of minerals under low temperature and pressure induced by hydrothermal activity. The crystallization of zeolite minerals in the pore space promotes an increase in crystallinity and therefore a decrease in porosity. Hence, the velocity of P-waves passing through a zeolitized ignimbrite will be considerably higher compared to those in unaltered counterparts. Within the scope of a TUBİTAK project (No:113Y439) in which the alteration properties of Cappadocian Ignimbrites (Nevşehir, Turkey) are being investigated, in-situ UPV measurements have been performed using a portable pulse test instrument. The acquired velocity data has been correlated with the modal proportions of secondary zeolite minerals obtained by SEM-EDS. The results demonstrate that the measured P

  17. Constraining entropic cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Koivisto, Tomi S. [Institute for Theoretical Physics and the Spinoza Institute, Utrecht University, Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands); Mota, David F. [Institute of Theoretical Astrophysics, University of Oslo, 0315 Oslo (Norway); Zumalacárregui, Miguel, E-mail: t.s.koivisto@uu.nl, E-mail: d.f.mota@astro.uio.no, E-mail: miguelzuma@icc.ub.edu [Institute of Cosmos Sciences (ICC-IEEC), University of Barcelona, Marti i Franques 1, E-08028 Barcelona (Spain)

    2011-02-01

    It has been recently proposed that the interpretation of gravity as an emergent, entropic phenomenon might have nontrivial implications to cosmology. Here several such approaches are investigated and the underlying assumptions that must be made in order to constrain them by the BBN, SneIa, BAO and CMB data are clarified. Present models of inflation or dark energy are ruled out by the data. Constraints are derived on phenomenological parameterizations of modified Friedmann equations and some features of entropic scenarios regarding the growth of perturbations, the no-go theorem for entropic inflation and the possible violation of the Bekenstein bound for the entropy of the Universe are discussed and clarified.

  18. Zeolite and swine inoculum effect on poultry manure biomethanation

    DEFF Research Database (Denmark)

    Kougias, Panagiotis; Fotidis, Ioannis; Zaganas, I.D.

    2013-01-01

    Poultry manure is an ammonia-rich substrate that inhibits methanogenesis, causing severe problems to the anaerobic digestion process. In this study, the effect of different natural zeolite concentrations on the mesophilic anaerobic digestion of poultry waste inoculated with well-digested swine...... manure was investigated. A significant increase in methane production was observed in treatments where zeolite was added, compared to the treatment without zeolite.Methane production in the treatment with 10 g dm-3 of natural zeolite was found to be 109.75% higher compared to the treatment without...... zeolite addition. The results appear to be influenced by the addition of zeolite, which reduces ammonia toxicity in anaerobic digestion and by the ammonia-tolerant swine inoculum....

  19. Zeolites as candidate materials for aqueous tritiated waste storage

    International Nuclear Information System (INIS)

    Todorovic, M.; Radak-Jovanovic, Z.; Gal, I.J.; Brucher, H.

    1987-01-01

    Zeolites have been considered as storage materials for aqueous tritiated waste, owing to their relatively high water contents, low diffusion coefficient of water in their pores and their accessibility. The diffusion coefficient of tritiated water in the solid particles seems to be the most important factor in the selection of zeolites for tritiated water storage. This work summarizes investigations done in The Boris Kidric Institute and Juelich Nuclear Research Center on zeolites as storage materials for tritiated water. Modified 4A zeolites as CsA, ZnA, CoA, Fe(III)A, as well as synthetic and natural analcime, have been investigated. Self-diffusion coefficients of THO in zeolites have been calculated using the Boyd-Reichenberg model of diffusion. The results obtained are discussed from the point of view of using zeolites as storage materials for tritiated waste water. In this respect, natural and synthetic analcime seem to be promising

  20. Synthesis of Silicalite Membrane with an Aluminum-Containing Surface for Controlled Modification of Zeolitic Pore Entries for Enhanced Gas Separation

    Directory of Open Access Journals (Sweden)

    Shaowei Yang

    2018-02-01

    Full Text Available The separation of small molecule gases by membrane technologies can help performance enhancement and process intensification for emerging advanced fossil energy systems with CO2 capture capacity. This paper reports the demonstration of controlled modification of zeolitic channel size for the MFI-type zeolite membranes to enhance the separation of small molecule gases such as O2 and N2. Pure-silica MFI-type zeolite membranes were synthesized on porous α-alumina disc substrates with and without an aluminum-containing thin skin on the outer surface of zeolite membrane. The membranes were subsequently modified by on-stream catalytic cracking deposition (CCD of molecular silica to reduce the effective openings of the zeolitic channels. Such a pore modification caused the transition of gas permeation from the N2-selective gaseous diffusion mechanism in the pristine membrane to the O2-selective activated diffusion mechanism in the modified membrane. The experimental results indicated that the pore modification could be effectively limited within the aluminum-containing surface of the MFI zeolite membrane to minimize the mass transport resistance for O2 permeation while maintaining its selectivity. The implications of pore modification on the size-exclusion-enabled gas selectivity were discussed based on the kinetic molecular theory. In light of the theoretical analysis, experimental investigation was performed to further enhance the membrane separation selectivity by chemical liquid deposition of silica into the undesirable intercrystalline spaces.

  1. Treatments of reverse osmosis concentrate using natural zeolites

    OpenAIRE

    Taherifar Hossein; Rezvantalab Sima; Bahadori Fatemeh; Khoei Omid Sadrzadeh

    2015-01-01

    The purpose of the current study is to experimentally investigate the reduction of sodium adsorption ratio (SAR) from a concentrated stream of reversed osmosis (RO) using natural zeolites. In order to reduce the salinity of solution, experiments were carried out using zeolites of varying concentration, pretreatment of adsorbents, and the addition of Ethylenediaminetetraacetic acid (EDTA). The results show that both zeolites can be used in an RO brine treatment; however, Rhyolitic tuff is more...

  2. Multi-elemental characterization of Cuban natural zeolites

    International Nuclear Information System (INIS)

    Diaz Rizo, O.; Herrera Peraza, E.F.

    1996-01-01

    Concentrations of 38 elements in samples from four important Cuban zeolite bed have beam obtained by Instrumental Neutron Activation (INAA) and X-Ray Fluorescence Analysis (XRFA). In comparison with other analytical techniques good agreement was achieved. The concentration values of minor element Ba, Sr, Zn, and Mn, and 25 trace element (including 9 REE) are at the first time reported in Cuban zeolite. It is important for the zeolite evaluation in different industrial uses

  3. Influence of zeolite nanofillers on properties of polymeric materials

    OpenAIRE

    Kopcová, M.; Ondrušová, D.; Krmela, J.; Průša, P.; Pajtášová, M.; Jankurová, Z.

    2012-01-01

    The present work deals with the preparation and study of modified polymeric materials with the replacement of carbon black by nanofillers on the basis of zeolite that is environmentally friendly. Natural zeolites from a group of aluminosilicate nanoporous materials have wide range of possibilities for applications that are environmentally friendly. Zeolites can be used in the role of fillers into the polymer materials too [1]. The given work deals with the preparation and study of modif...

  4. Aqueous interactions of zeolitic material in acidic and basic solutions

    OpenAIRE

    Polatoğlu, İlker; Çakıcıoğlu Özkan, Seher Fehime

    2010-01-01

    Aqueous interactions of natural zeolitic material in as-received and modified forms were studied. The zeolitic materials was interacted with acidic (hydrochloric acid, lactic acid, acetic acid) and basic (sodium hydroxide) solutions. Ion exchange, adsorption, complex formation, precipitation and cation hydrolysis were possible interaction mechanisms affected by the amount and cation content of zeolite and pH. The dominant mechanisms seemed to be ion exchange and adsorption in HCl solution whe...

  5. Phonolite-hosted zeolite deposits in the Kaiserstuhl Volcanic Complex, Germany

    Science.gov (United States)

    Weisenberger, Tobias; Spürgin, Simon

    2014-05-01

    Several subvolcanic phonolitic intrusions occur within the Miocene Kaiserstuhl Volcanic Complex (KVC) located in the central-southern segment of the Upper Rhine Graben, which is part of the European Cenozoic Rift System. Hydrothermally altered phonolitic rocks are of economic interest, due to the high (>40 wt%) zeolite content, which accounts for the remarkable zeolitic physicochemical properties of the ground rock. These properties have widespread industrial application in water softening, catalysis, remediation of soils and soil quality, wastewater treatment, and as additive in the cement industry. Currently the largest phonolite intrusion Fohberg is active in mining, located in the eastern part of the KVC. The Endhale phonolite, approximately 1.5 km to the north marks a further deposit currently under exploration. Both phonolites are hosted in Tertiary sedimentary units. The aim of this study is to carry out a new mineralogical and geochemical data a) to evaluate the manifestation of hydrothermal alteration of the Fohberg and Endhale phonolitic intrusions, and b) to constrain the physical and chemical properties of the fluids, which promoted hydrothermal replacement of primary igneous minerals. The high degree of alteration is in contrast to the only slightly altered Kirchberg phonolite in the western KVC. The alkaline intrusive bodies are characterized by the primary mineralogy: feldspathoid mineral, K-feldspar, aegirine-augite, wollastonite, and andradite, with additional REE-minerals (e.g. götzenite). Fluid-induced re-equilibration of feldspathoid minerals and wollastonite caused breakdown to a set of secondary phases. Feldspathoid minerals are totally replaced by secondary phases including various zeolite species, calcite, and barite. Wollastonite breakdown results in the formation of various zeolites, calcite, pectolite, sepiolite, and quartz. The large variability of secondary minerals indicates a heterogenic fluid composition throughout the phonolitic

  6. Formal language constrained path problems

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, C.; Jacob, R.; Marathe, M.

    1997-07-08

    In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a formal language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free language is solvable efficiently in polynomial time, when the mode choice is specified as a regular language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.

  7. ZEOLITIZATION OF SEWAGE SLUDGE ASH WITH A FUSION METHOD

    Directory of Open Access Journals (Sweden)

    Jolanta Latosińska

    2016-11-01

    Full Text Available The study shows the results of zeolitization of municipal sewage sludge ash with the indirect fusion method followed by a hydrothermal method. The zeolitization of sewage sludge ash was conducted at the melting temperature of 550°C and the melting time of 60 minutes, crystallization temperatures of 60°C and 90°C, crystallization time of 6 hours and the SSA:NaOH ratio of 1:1.8; 1:1.4. The research of modified sewage sludge ashes included the observation of changes of ash particles surface and the identification of crystalized phases. The zeolitization of sewage sludge ash at the ratio of SSA:NaOH 1.0:1.4 did not cause the formation of zeolite phases. On the other hand, the zeolitization at the ratio of SSA:NaOH 1.0:1.8 resulted in the formation of desired zeolite phases such as zeolite Y (faujasite and hydroxysodalite. The presented method of sewage sludge ash zeolitization allows to obtain highly usable material. Synthesized zeolites may be used as adsorbents and ion exchangers. They can be potentially used to remove heavy metals as well as ammonia from water and wastewater.

  8. Aluminum-rich mesoporous MFI - type zeolite single crystals

    DEFF Research Database (Denmark)

    Kustova, Marina; Kustov, Arkadii; Christensen, Christina Hviid

    2005-01-01

    are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature programmed desorption (NH3-TPD), and N-2 adsorption measurements. The obtained zeolites combine the high crystallinity and the characteristic micropores of zeolites with an intracrystalline mesopore system....... With this technique, only zeolites with relatively low Al contents were reported (Si/Al ratio about 100). In this work, the preparation of aluminum-rich mesoporous MFI-type zeolite single crystals (Si/Al similar to 16-50) using aluminum isopropoxide as the aluminum Source is reported for the first time. All samples...

  9. Human bile sorption by cancrinite-type zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Linares, Carlos F. [Laboratorio de Catalisis y Metales de Transicion, Facultad de Ciencias y Tecnologia, Departamento de Quimica, Universidad de Carabobo, Valencia. Edo. Carabobo, Apartado Postal 3336 (Venezuela, Bolivarian Republic of)], E-mail: clinares@uc.edu.ve; Colmenares, Maryi; Ocanto, Freddy [Laboratorio de Catalisis y Metales de Transicion, Facultad de Ciencias y Tecnologia, Departamento de Quimica, Universidad de Carabobo, Valencia. Edo. Carabobo, Apartado Postal 3336 (Venezuela, Bolivarian Republic of); Valbuena, Oscar [Facultad de Ciencias y Tecnologia, Departamento de Biologia, Universidad de Carabobo, Valencia. Edo. Carabobo, Apartado Postal 3336 (Venezuela, Bolivarian Republic of)], E-mail: ovalbuena@uc.edu.ve

    2009-01-01

    A nitrated cancrinite-type zeolite was synthesized from zeolite X, NaOH and NaNO{sub 3} solutions under autogeneous pressure at 80 deg. C for 48 h. This zeolite was characterized by X-ray diffraction (XRD), FT-IR-spectroscopy, scanning electron microscopy (SEM) and BET surface area. XRD, SEM and FT-IR confirmed the presence of nitrated cancrinite-type zeolite without other collateral phases as sodalite. Then, this sodium zeolite was exchanged with potassium and calcium cations and finally, these modified zeolites were reacted with biliar solutions from human gallbladder. Several factors such as: mass of used cancrinite, nature of the exchanged cation and reaction time of the cancrinite-bile solution interactions were studied. The composition of bile solutions (bile acids, phospholipids and bilirubin) was analyzed before and after the cancrinite-bile solution reaction. Results showed that the components of the bile were notably reduced after the contact with solids. Ca-cancrinite, 120 min of reaction time and 500 mg of solids were the best conditions determined for the bile acid reduction in human bile. When the modified zeolites were compared with the commercial cholestyramine, it was found that zeolites were more active than the latter. These zeolites may be an alternative choice to diminish cholesterol levels in hypercholesterolemic patients.

  10. Hydrothermal synthesis of free-template zeolite T from kaolin

    Science.gov (United States)

    Arshad, Sazmal E.; Yusslee, Eddy F.; Rahman, Md. Lutfor; Sarkar, Shaheen M.; Patuwan, Siti Z.

    2017-12-01

    Free-template zeolite T crystals were synthesized via hydrothermal synthesis by utilizing the activated kaolin as silica and alumina source, with the molar composition of 1 SiO2: 0.04 Al2O3: 0.26 Na2O: 0.09 K2O: 14 H2O. Observation of the formation of free-template zeolite crystals were done at temperature 90°C, 100 °C and 110 °C respectively. It was therefore determined that during the 120 h of the synthesis at 90 °C, zeolite T nucleated and formed a first competitive phase with zeolite L. As temperature increases to 100 °C, zeolite T presented itself as a major phase in the system at time 168 h. Subsequently, development of Zeolite T with second competitive phase of zeolite W was observed at temperature 110 °C. In this study, XRD and SEM instruments were used to monitor the behavior of zeolite T crystals with respect of temperature and time. By using natural resource of kaolin clay as a starting material, this paper hence aims to provide new findings in synthesis of zeolite T using low energy consumption and low production cost.

  11. Progress on Zeolite-membrane-aided Organic Acid Esterification

    Science.gov (United States)

    Makertiharta, I. G. B. N.; Dharmawijaya, P. T.

    2017-07-01

    Esterification is a common route to produce carboxylic acid esters as important intermediates in chemical and pharmaceutical industries. However, the reaction is equilibrium limited and needs to be driven forward by selective removal one of the products. There have been some efforts to selectively remove water from reaction mixture via several separation processes (such as pervaporation and reactive distillation). Integrated pervaporation and esterification has gained increasing attention towards. Inorganic zeolite is the most popular material for pervaporation due to its high chemical resistant and separation performance towards water. Zeolite also has proven to be an effective material in removing water from organic compound. Zeolite can act not only as selective layer but also simultaneously act as a catalyst on promoting the reaction. Hence, there are many configurations in integrating zeolite membrane for esterification reaction. As a selective layer to remove water from reaction mixture, high Si/Al zeolite is preferred to enhance its hydrophilicity. However, low Si/Al zeolite is unstable in acid condition due to dealumination thus eliminate its advantages. As a catalyst, acid zeolites (e.g. H-ZSM-5) provide protons for autoprotolysis of the carboxylic acid similar to other catalyst for esterification (e.g. inorganic acid, and ion exchange resins). There are many studies related to zeolite membrane aided esterification. This paper will give brief information related to zeolite membrane role in esterification and also research trend towards it.

  12. Influencing the selectivity of zeolite Y for triglycine adsorption.

    Science.gov (United States)

    Wijntje, R; Bosch, H; de Haan, A B; Bussmann, P J T

    2007-02-16

    In prior work we studied the adsorption of triglycine on zeolite Y under reference conditions. This study aims to solve the question of which adsorbent properties and process conditions influence the adsorption triglycine from an aqueous solution by zeolite Y. Relevant zeolite parameters to study are: the amount of acidic sites (Si/Al(2) ratio), counter ion, micropore structure. Process conditions that may influence triglycine adsorption are pH, other components such as sugars, amino acids and salts, and temperature. Adsorption of triglycine on zeolite HY is dominated by ionic interaction. The capacity and selectivity of zeolite HY for triglycine can be changed by choosing different Si/Al(2) ratios or changing the counter ion. The presence of cations and basic anions in solutions reduces triglycine adsorption. Fructose and glycine have no significant influence on triglycine adsorption. Temperature only has a slight influence. The pore structure of zeolite Y is not a critical factor for triglycine adsorption, provided pores are accessible to triglycine and in the micropore range (<2 nm). While this allows other zeolites than zeolite Y to be applied, the presence of the supercage structure of zeolite Y is beneficial to obtain better adsorption of triglycine in its neutral form.

  13. Regeneration of zeolite catalysts of isobutane alkylation with butenes

    Energy Technology Data Exchange (ETDEWEB)

    Manza, I.A.; Tsupryk, I.N.; Bartyshevskii, V.A.; Gaponenko, O.I.; Petrilyak, K.I.

    1986-12-10

    The industrial adoption of alkylation of isoalkanes with alkenes is held back by the rapid and irreversible deactivation of the zeolite catalysts appropriate to the process. This paper is aimed specifically at the restoration of the catalytic activity and increase in the service life of zeolite alkylation catalysts. The catalyst chosen for the investigation was HLaCaNaX zeolite both unmodified and modified with various multivalence cations. The thermochemical and oxidative regeneration process as well as the equipment utilized are described. Both the advantages and the drawbacks of the method are given; explanations for the possibly irreversible losses of the catalytic properties in the regenerated zeolites are also put forward.

  14. Performance of zeolite scavenge column in Xe monitoring system

    International Nuclear Information System (INIS)

    Wang Qian; Wang Hongxia; Li Wei; Bian Zhishang

    2010-01-01

    In order to improve the performance of zeolite scavenge column, its ability of removal of humidity and carbon dioxide was studied by both static and dynamic approaches. The experimental results show that various factors, including the column length and diameter, the mass of zeolite, the content of water in air, the temperature rise during adsorption, and the activation effectiveness all effect the performance of zeolite column in scavenging humanity and carbon dioxide. Based on these results and previous experience, an optimized design of the zeolite column is made for use in xenon monitoring system. (authors)

  15. Selective Production of Aromatics from 2-Octanol on Zinc Ion-Exchanged MFI Zeolite Catalysts

    Directory of Open Access Journals (Sweden)

    Masakazu Iwamoto

    2015-12-01

    Full Text Available The aromatization of 2-octanol derived from castor oil as a byproduct in the formation of sebacic acid was investigated on various zeolite catalysts. Zn ion-exchanged MFI (ZSM-5 zeolites with small silica/alumina ratios and zinc contents of 0.5 to 2.0 wt. % were determined to exhibit good and stable activity for the reaction at 623 to 823 K. The yield of aromatics was 62% at 773 K and the space velocity 350 to 1400 h−1. The temperature and contact time dependences of the product distributions indicated the reaction pathways of 2-octanol→dehydration to 2-octene→decomposition to C5 and C3 compounds→further decomposition to small alkanes and alkenes→aromatization with dehydrogenation. Alcohols with carbon numbers of 5 to 8 exhibited similar distributions of products compared to 2-octanol, while corresponding carbonyl compounds demonstrated different reactivity.

  16. Rapid crystallization and morphological adjustment of zeolite ZSM-5 in nonionic emulsions

    Science.gov (United States)

    Zhang, Ying; Jin, Chao

    2011-01-01

    Zeolite ZSM-5 was synthesized for the first time in a nonionic emulsion composed of polyoxyethylated alkylphenol, butanol, cyclohexane and tetraethylammonium hydroxide (TEAOH)-containing zeolite synthesis mixture. The crystallization kinetics in the emulsion was investigated and the ZSM-5 product was characterized in detail by XRD, SEM, FT-IR, TG, N 2 adsorption and CHN analysis techniques. Compared with the conventionally hydrothermal synthesis with the same structure directing agent TEAOH, the emulsion system allows rapid crystallization of ZSM-5. The ZSM-5 product exhibits unusual agglomerated structure and possesses larger specific surface area. The FT-IR, TG results plus CHN analysis show the encapsulation of a trace of emulsion components in the emulsion ZSM-5. Control experiments show the emulsion system exerts the crystallization induction and morphological adjustment effects mainly during the aging period. The effects are tentatively attributed to the confined space domains, surfactant-water interaction as well as surfactant-growing crystals interaction existing in the emulsion.

  17. A modeling study of methane hydrate decomposition in contact with the external surface of zeolites.

    Science.gov (United States)

    Smirnov, Konstantin S

    2017-08-30

    The behavior of methane hydrate (MH) enclosed between the (010) surfaces of the silicalite-1 zeolite was studied by means of molecular dynamics simulations at temperatures of 150 and 250 K. Calculations reveal that the interaction with the hydrophilic surface OH groups destabilizes the clathrate structure of hydrate. While MH mostly conserves the structure in the simulation at the low temperature, thermal motion at the high temperature breaks the fragilized cages of H-bonded water molecules, thus leading to the release of methane. The dissociation proceeds in a layer-by-layer manner starting from the outer parts of the MH slab until complete hydrate decomposition. The released CH 4 molecules are absorbed by the microporous solid, whereas water is retained at the surfaces of hydrophobic silicalite and forms a meniscus in the interlayer space. Methane uptake reaches 70% of the silicalite sorption capacity. The energy necessary for the endothermic MH dissociation is supplied by the exothermic methane absorption by the zeolite.

  18. Zeolites as possible biofortifiers in Maitake cultivation

    Directory of Open Access Journals (Sweden)

    Vunduk Jovana

    2014-01-01

    Full Text Available The levels of Ni, Cu and Mg in Grifola frondosa (also known as Maitake mushroom fruit body produced on zeolite Minazel Plus (MG-supplemented substrate were measured with inductively coupled plasma optical emission spectrometry (ICP-OES. Two different concentrations of MG were added to the substrate for mushroom cultivation. Levels of selected metals were measured in cultivated dry carpophores. The content of Ni increased in fruit bodies produced on supplemented substrate, while in case of Cu, a pronounced decrease was observed. When two different concentrations of MG were implemented, the Mg level showed both positive and negative trend, depending on the applied concentration of zeolite. MG in a concentration of 1% showed the strongest influence on the observed elements in the cultivated fruiting body of Maitake mushroom. [Projekat Ministarstva nauke Republike Srbije, br. 46010

  19. Sharp spatially constrained inversion

    DEFF Research Database (Denmark)

    Vignoli, Giulio G.; Fiandaca, Gianluca G.; Christiansen, Anders Vest C A.V.C.

    2013-01-01

    We present sharp reconstruction of multi-layer models using a spatially constrained inversion with minimum gradient support regularization. In particular, its application to airborne electromagnetic data is discussed. Airborne surveys produce extremely large datasets, traditionally inverted...... by using smoothly varying 1D models. Smoothness is a result of the regularization constraints applied to address the inversion ill-posedness. The standard Occam-type regularized multi-layer inversion produces results where boundaries between layers are smeared. The sharp regularization overcomes...... inversions are compared against classical smooth results and available boreholes. With the focusing approach, the obtained blocky results agree with the underlying geology and allow for easier interpretation by the end-user....

  20. Ring-constrained Join

    DEFF Research Database (Denmark)

    Yiu, Man Lung; Karras, Panagiotis; Mamoulis, Nikos

    2008-01-01

    We introduce a novel spatial join operator, the ring-constrained join (RCJ). Given two sets P and Q of spatial points, the result of RCJ consists of pairs (p, q) (where p ε P, q ε Q) satisfying an intuitive geometric constraint: the smallest circle enclosing p and q contains no other points in P, Q....... This new operation has important applications in decision support, e.g., placing recycling stations at fair locations between restaurants and residential complexes. Clearly, RCJ is defined based on a geometric constraint but not on distances between points. Thus, our operation is fundamentally different...... from the conventional distance joins and closest pairs problems. We are not aware of efficient processing algorithms for RCJ in the literature. A brute-force solution requires computational cost quadratic to input size and it does not scale well for large datasets. In view of this, we develop efficient...

  1. Zeolite membranes for effective production of biofuels

    OpenAIRE

    Sjöberg, Erik

    2012-01-01

    To deal with the increasing demand of renewable fuels, more efficient processes for the production of biofuels are needed. Zeolite membranes have the potential to improve many existing processes that could be used for production of biofuels. Methanol is a potential biofuel that may be produced from synthesis gas in an equilibrium limited reaction. The production of methanol from synthesis gas could be improved by use of a membrane reactor, which could increase the conversion of synthesis gas ...

  2. Acylation Reactions over Zeolites and Mesoporous Catalysts

    Czech Academy of Sciences Publication Activity Database

    Voláková, Martina; Vitvarová, Dana; Čejka, Jiří

    2009-01-01

    Roč. 2, č. 6 (2009), s. 486-499 ISSN 1864-5631 R&D Projects: GA ČR GA104/07/0383; GA ČR GD203/08/H032; GA MPO FT-TA5/005 Institutional research plan: CEZ:AV0Z40400503 Keywords : acylation * ketones * mesoporous materials * shape-selectivity * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.767, year: 2009

  3. Transformations of aromatic hydrocarbons over zeolites

    Czech Academy of Sciences Publication Activity Database

    Voláková, Martina; Žilková, Naděžda; Čejka, Jiří

    2008-01-01

    Roč. 34, 5-7 (2008), s. 439-454 ISSN 0922-6168 R&D Projects: GA ČR GA203/05/0197; GA AV ČR 1QS400400560; GA AV ČR KJB4040402 Institutional research plan: CEZ:AV0Z40400503 Keywords : aromatic hydrocarbons * zeolites * alkylation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.514, year: 2008

  4. Characterization of active sites in zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, J. [Los Alamos National Lab., NM (United States); Bug, A. [Swarthmore Coll., PA (United States); Nicol, J.M. [MOLTECH (United States)] [and others

    1997-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Atomic-level details of the interaction of adsorbed molecules with active sites in catalysts are urgently needed to facilitate development of more effective and/or environmentally benign catalysts. To this end the authors have carried out neutron scattering studies combined with theoretical calculations of the dynamics of small molecules inside the cavities of zeolite catalysts. The authors have developed the use of H{sub 2} as a probe of adsorption sites by observing the hindered rotations of the adsorbed H{sub 2} molecule, and they were able to show that an area near the four-rings is the most likely adsorption site for H{sub 2} in zeolite A while adsorption of H{sub 2} near cations located on six-ring sites decreases in strength as Ni {approximately} Co > Ca > Zn {approximately} Na. Vibrational and rotational motions of ethylene and cyclopropane adsorption complexes were used as a measure for zeolite-adsorbate interactions. Preliminary studies of the binding of water, ammonia, and methylamines were carried out in a number of related guest-host materials.

  5. Periodic modeling of zeolite Ti-LTA.

    Science.gov (United States)

    Hernandez-Tamargo, Carlos E; Roldan, Alberto; Ngoepe, Phuti E; de Leeuw, Nora H

    2017-08-21

    We have proposed a combination of density functional theory calculations and interatomic potential-based simulations to study the structural, electronic, and mechanical properties of pure-silica zeolite Linde Type A (LTA), as well as two titanium-doped compositions. The energetics of the titanium distribution within the zeolite framework suggest that the inclusion of a second titanium atom with configurations Ti-(Si) 0 -Ti, Ti-(Si) 1 -Ti, and Ti-(Si) 2 -Ti is more energetically favorable than the mono-substitution. Infra-red spectra have been simulated for the pure-silica LTA, the single titanium substitution, and the configurations Ti-(Si) 0 -Ti and Ti-(Si) 2 -Ti, comparing against experimental benchmarks where available. The energetics of the direct dissociation of water on these Lewis acid sites indicate that this process is only favored when two titanium atoms form a two-membered ring (2MR) sharing two hydroxy groups, Ti-(OH) 2 -Ti, which suggests that the presence of water may tune the distribution of titanium atoms within the framework of zeolite LTA. The electronic analysis indicates charge transfer from H 2 O to the Lewis acid site and hybridization of their electronic states.

  6. Isotopic exchange of deuterium in zeolites

    International Nuclear Information System (INIS)

    Novakova, J.; Kubelkova, L.; Jiru, P.

    1981-01-01

    The information obtainable from the study of deuterium isotope exchange in zeolites by i.r. and m.s. methods is discussed. The conditions necessary for high sensitivity determination of OH groups by gas-phase analysis are mentioned together with a determination of the hydroxyl number in the 3 types of OH groups found in HNaY zeolite by solid-phase analysis. The advantage of the i.r. method in the study of hydroxyl heterogeneity in isotopic exchange is compared with the limited success of the m.s. method. The evaluation of the rates of homo- and hetero-exchange and their dependences on cationic exchange, stabilization and the pretreatment of Msup(n+)HY zeolites are shown. The activation of hydrogen molecules seems to be the slowest step in the exchange which proceeds by a single-step mechanism. The OH groups alone do not activate hydrogen molecules as opposed to Lewis sites formed by dehydroxylation and cations and/or metal particles in suitable concentrations at suitable locations. (author)

  7. Adsorption of ions onto treated natural zeolite

    Directory of Open Access Journals (Sweden)

    Cristiane da Rosa Oliveira

    2007-12-01

    Full Text Available This work presents studies of modification of a natural zeolite by activation with Na+ cations and functionalisation with Ba+2 and/or Cu2+ ions (FZ. The zeolite was characterized, modified and applied in adsorption studies of sulphate and isopropilxanthate ions as flocculated and powdered forms. The reuse of SO4Ba-FZ was investigated by adsorption-removal of either Ba2+ or sulphate ions in stages. Equilibrium data showed that the FZ, flocculated or as powder, provide considerable removal of sulphate ions (q mLangmuir: 1.15 and 1.35 meq.g-1, respectively and isopropilxanthate (q mLangmuir: 0.35 and 0.93 meq.g-1, respectively. The reuse of the SO4-FZ, either powdered or flocculated also uptake significant amount of Ba2+ or sulphate ions (q mLangmuir: 1.15 meq.g-1, providing a new alternative for the exhausted adsorbent. Thus the activated and functionalised zeolites create new options on the materials engineering area with applications in environmental applied adsorption processes.

  8. Hydrophilic and hydrophobic adsorption on Y zeolites

    Science.gov (United States)

    Halasz, Istvan; Kim, Song; Marcus, Bonnie

    The uniform large micropores of hydrothermally stable Y zeolites are used widely to confine both polar and non-polar molecules. This paper compares the physisorption of water, methanol, cyclohexane, benzene and other adsorbates over various Y zeolites. These adsorbents are commercial products with reproducibly controllable physical and chemical characteristics. Results indicate that the type I isotherms typical for micropore adsorption can turn into type II or type III isotherms depending on either or both the hydrophobicity of the adsorbent and the polarity of the adsorbate. Methanol produced a rare type V isotherm not reported over zeolites before. Canonical and grand canonical Monte Carlo molecular simulations with Metropolis importance sampling reproduced the experimental isotherms and showed characteristic geometric patterns for molecules confined in Na-X, Na-Y, dealuminated Y, and ZSM5 structures. Adsorbate-adsorbate interactions seem to determine the micropore condensation of both polar and non-polar molecules. Exchanged ions and lattice defects play a secondary role in shaping the adsorption isotherms. The force field of hydrophobic Y appears to exert an as yet unexplored sieving effect on adsorbates having different dipole moments and partial charge distributions. This mechanism is apparently different from both the monolayer formation controlled adsorption on hydrophobic mesopores and macropores and the polarizability and small-pore opening controlled micropore confinement in hydrophobic ZSM5.

  9. Hierarchical zeolites: progress on synthesis and characterization of mesoporous zeolite single crystal catalysts

    DEFF Research Database (Denmark)

    Kustova, Marina; Egeblad, Kresten; Christensen, Claus H.

    2007-01-01

    in a hierarchical pore size distribution. In this work, the preparation of mesoporous ZSM-12 single crystal catalysts using a new improved procedure for directly introducing carbon in the reaction mixture is reported. The microwave heating technique is also applied for the synthesis of mesoporous silicalite-1...... measurements. Additionally, the results of diffusion of n-hexadecane in conventional and mesoporous zeolites are presented. Isomerization and cracking of n-hexadecane was chosen as model test reaction for these materials. All results support that mesoporous zeolites are superior catalysts due to improved mass...

  10. New antiaxillary odour deodorant made with antimicrobial Ag-zeolite (silver-exchanged zeolite).

    Science.gov (United States)

    Nakane, T; Gomyo, H; Sasaki, I; Kimoto, Y; Hanzawa, N; Teshima, Y; Namba, T

    2006-08-01

    The causative substances for axillary osmidrosis, which are often found in apocrine sweat, are the decomposed/denatured products of short-chain fatty acid and other biological metabolite compounds produced by axillary-resident bacteria. Conventional underarm deodorants suppress the process of odour production mostly by the following mechanism: (1) suppression of perspiration, (2) reduction in numbers of resident bacteria, (3) deodorization and (4) masking. The most important and effective method to reduce odour is to suppress the growth of resident bacteria with antimicrobials, which have several drawbacks, especially in their safety aspect. To solve these problems, we focused on Ag-zeolite (silver-exchanged zeolite) that hold stable Ag, an inorganic bactericidal agent, in its structure, and therefore, poses less risk in safety. Its bactericidal effect on skin-resident bacteria was found to be excellent and comparable with that of triclosan, a most frequently used organic antimicrobial in this product category. The dose-response study of Ag-zeolite powder spray (0-40 w/w%) using 39 volunteers revealed that 5-40 w/w% Ag-zeolite could show a sufficient antimicrobial effect against skin-resident bacteria. The comparison study using 0.2 w/w% triclosan as the control and 10 w/w% Ag-zeolite indicated that: (1) one application of the powder spray containing 10 w/w% Ag-zeolite could show a sufficient antimicrobial effect against the resident bacteria and its effect continued for 24 h, (2) a powder spray containing 0.2 w/w% triclosan was unable to show a sufficient antimicrobial effect, and (3) no adverse event was observed. These studies show that Ag-zeolite has a superior antimicrobial ability that is rarely found in conventional antimicrobials used in deodorant products and a strong antiaxillary odour deodorant ability because of its long-lasting effect. During clinical study, patch tests with humans and other clinical studies of this product showed no adverse events

  11. Comparing charcoal and zeolite reflection filters for volatile anaesthetics: A laboratory evaluation.

    Science.gov (United States)

    Sturesson, Louise W; Frennström, Jan O; Ilardi, Marcella; Reinstrup, Peter

    2015-08-01

    A modified heat-moisture exchanger that incorporates a reflecting filter for use with partial rebreathing of exhaled volatile anaesthetics has been commercially available since the 1990 s. The main advantages of the device are efficient delivery of inhaled sedation to intensive care patients and reduced anaesthetic consumption during anaesthesia. However, elevated arterial CO2 values have been observed with an anaesthetic conserving device compared with a conventional heat and moisture exchanger, despite compensation for larger apparatus dead space. The objective of this study is to thoroughly explore the properties of two reflecting materials (charcoal and zeolites). A controlled, prospective, observational laboratory study. Lund University Hospital, Sweden, from December 2011 to December 2012. None. Three filters, with identical volumes, were compared using different volatile anaesthetics at different conditions of temperature and moisture. The filtering materials were charcoal or zeolite. Glass spheres were used as an inert control. Consumption of volatile anaesthetics using different reflecting materials in filters at different conditions regarding temperature and moisture. CO2 reflection by the filtering materials: glass spheres, charcoal or zeolite. Isoflurane consumption in an open system was 60.8 g h(-1). The isoflurane consumption in dry, warm air was 39.8 g h(-1) with glass spheres. Changing to charcoal and zeolite had a profound effect on isoflurane consumption, 11.8 and 10.7 g h(-1), respectively. Heating and humidifying the air as well as the addition of N2O created only minor changes in consumption. The percentage of isoflurane conserved by the charcoal filter was independent of the isoflurane concentration (0.5 to 4.5%). Reflection of sevoflurane, desflurane and halothane by the charcoal filter was similar to reflection of isoflurane. Both charcoal and zeolite filters had CO2 reflecting properties and end-tidal CO2 increased by 3 to 3.7% compared

  12. Design and characterization of chitosan/zeolite composite films — Effect of zeolite type and zeolite dose on the film properties

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Gustavo P.; Debone, Henrique S. [Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema (Brazil); Severino, Patrícia [Universidade Tiradentes, Instituto de Tecnologia e Pesquisa, Aracaju (Brazil); Souto, Eliana B. [Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra (Portugal); Center for Neuroscience and Cell Biology & Institute for Biomedical Imaging and Life Sciences (CNC-IBILI), University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra (Portugal); Silva, Classius F. da, E-mail: cfsilva@unifesp.br [Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema (Brazil)

    2016-03-01

    Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance. - Highlights: • Zeolite/chitosan composite films were prepared by casting technique. • Micrographs showed slight difference according to the content and A-type zeolite. • The barrier properties of the films were suitable to the dressing application. • Film characterization suggested that zeolites interacted with the chitosan chain.

  13. Comparison of the defluoridation capacity of zeolites from Ethiopia ...

    African Journals Online (AJOL)

    Fluorosis, either dental or skeleton, is often due to the high fluoride content of well waters. In this work, using solutions which contain different amounts of fluoride, natural zeolites from Ethiopia and Mexico were tested. It is shown that, although zeolites are known to be cationic exchangers, their extra-framework aluminum ...

  14. Rotational dynamics of propylene inside Na-Y zeolite cages

    Indian Academy of Sciences (India)

    of propylene molecules (r ~ 1.91 Å), shape (asymmetry of propylene molecules) and higher concentration of propylene molecules in Na-Y zeolite (~5 molecules per supercage). References. [1] G Tomlinson, Modern zeolites, structure and function in detergents and petrochemicals. (Traw Tech Publications Ltd., Switzerland, ...

  15. Zeolite H-BEA catalysed multicomponent reaction: One-pot ...

    Indian Academy of Sciences (India)

    lent thermal stability which make them economically and environmentally feasible.2 The use of zeolites as a ... of zeolite H-BEA was added. The mixture was stirred under thermal solvent-free condition at 120. ◦. C in oil bath for 5–7min and the reaction was followed by. TLC. After completion of reaction, mass was cooled to.

  16. Inelastic neutron scattering from non-framework species within zeolites

    International Nuclear Information System (INIS)

    Newsam, J.M.; Brun, T.O.; Trouw, F.; Iton, L.E.; Curtiss, L.A.

    1990-01-01

    Inelastic and quasielastic neutron scattering have special advantages for studying certain of the motional properties of protonated or organic species within zeolites and related microporous materials. In this paper these advantages and various experimental methods are outlined, and illustrated by measurements of torsional vibrations and rotational diffusion of tetramethylammonium (TMA) cations occluded within zeolites TMA-sodalite, omega, ZK-4 and SAPO-20

  17. Structure modification of natural zeolite for waste removal application

    Science.gov (United States)

    Widayatno, W. B.

    2018-03-01

    Tremendous industrialization in the last century has led to the generation of huge amount of waste. One of the recent hot research topics is utilizing any advance materials and methods for waste removal. Natural zeolite as an inexpensive porous material with a high abundance holds a key for efficient waste removal owing to its high surface area. However, the microporous structure of natural zeolite hinders the adsorption of waste with a bigger molecular size. In addition, the recovery of natural zeolite after waste adsorption into its pores should also be considered for continuous utilization of this material. In this study, the porosity of natural zeolite from Tasikmalaya, Indonesia, was hydrothermally-modified in a Teflon-lined autoclave filled with certain pore directing agent such as distilled water, KOH, and NH4OH to obtain hierarchical pore structure. After proper drying process, the as-treated natural zeolite is impregnated with iron cation and heat-treated at specified temperature to get Fe-embedded zeolite structure. XRD observation is carried out to ensure the formation of magnetic phase within the zeolite pores. The analysis results show the formation of maghemite phase (γ-Fe2O3) within the zeolite pore structure.

  18. Nonionic emulsion-mediated synthesis of zeolite beta

    Indian Academy of Sciences (India)

    Zeolite beta synthesis was first carried out in a newly developed emulsion system containing nonionic polyoxyethylated alkylphenol surfactant, which showed interesting non-conventional features. Compared to the conventional hydrothermal synthesis of zeolite beta, the reported nonionic emulsion system showed a faster ...

  19. Use of Natural Zeolite to Upgrade Activated Sludge Process

    Directory of Open Access Journals (Sweden)

    Hanife Büyükgüngör

    2003-01-01

    Full Text Available The objective of this study was to achieve better efficiency of phosphorus removal in an enhanced biological phosphorus removal process by upgrading the system with different amounts of natural zeolite addition. The system performance for synthetic wastewater containing different carbon sources applied at different initial concentrations of phosphorus, as well as for municipal wastewater, was investigated. Natural zeolite addition in the aerobic phase of the anaerobic/aerobic bioaugmented activated sludge system contributed to a significant improvement of phosphorus removal in systems with synthetic wastewater and fresh municipal wastewater. Improvement of phosphorus removal with regard to the control reactors was higher with the addition of 15 than with 5 g/L of natural zeolite. In reactors with natural zeolite addition with regard to the control reactors significantly decreased chemical oxygen demand, ammonium and nitrate, while higher increment and better-activated sludge settling were achieved, without changes in the pH-values of the medium. It was shown that the natural zeolite particles are suitable support material for the phosphate-accumulating bacteria Acinetobacter calcoaceticus (DSM 1532, which were adsorbed on the particle surface, resulting in increased biological activity of the system. The process of phosphorus removal in a system with bioaugmented activated sludge and natural zeolite addition consisted of: metabolic activity of activated sludge, phosphorus uptake by phosphate-accumulating bacteria adsorbed on the natural zeolite particles and suspended in solution, and phosphorus adsorption on the natural zeolite particles.

  20. Efficacy of natural zeolite and pigments on yolk color and ...

    African Journals Online (AJOL)

    user

    2011-04-16

    Apr 16, 2011 ... The YI was significantly affected by zeolite and pigment levels. Hens fed zeolite tended (P = 0.062) to lay eggs with a lighter shell weight (%) during the entire period compared with the control group. This effect was signifi- cant in 49 to 50 weeks of age, in a quadratic manner. A linear decrease in YI between ...

  1. 3D Nanoscale Imaging and Quantitative Analysis of Zeolite Catalysts

    NARCIS (Netherlands)

    Zecevic, J.

    2013-01-01

    Zeolites are crystalline microporous aluminosilicates, one of the most versatile and widely used class of materials.The unique physico-chemical properties of zeolites are found to be irreplaceable in many industrial processes such as separation, adsorption and catalysis. To exploit their full

  2. Mesoporous zeolite and zeotype single crystals synthesized in fluoride media

    DEFF Research Database (Denmark)

    Egeblad, Kresten; Kustova, Marina; Klitgaard, Søren Kegnæs

    2007-01-01

    We report the synthesis and characterization of a series of new mesoporous zeolite and zeotype materials made available by combining new and improved procedures for directly introducing carbon into reaction mixtures with the fluoride route for conventional zeolite synthesis. The mesoporous...

  3. Defluorination of drinking water using surfactant modified zeolites ...

    African Journals Online (AJOL)

    This study focused on the removal of fluoridefrom groundwater by employing surfactant modified zeolites (SMZ) synthesized using locallyavailable kaolin material as precursor. The zeolite synthesis involved calcination of kaolin, alkaline fusion and hydrothermal treatment. The final product was modified with 5g/L ...

  4. Nonionic emulsion-mediated synthesis of zeolite beta

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Zeolite beta synthesis was first carried out in a newly developed emulsion system containing nonionic polyoxyethylated alkylphenol surfactant, which showed interesting non-conventional features. Compared to the conventional hydrothermal synthesis of zeolite beta, the reported nonionic emulsion system showed ...

  5. Zeolite Membranes : Ozone Detemplation, Modeling, and Performance Characterization

    NARCIS (Netherlands)

    Kuhn, J.

    2009-01-01

    Membrane technology plays an increasingly important role in developing a more sustainable process industry. Zeolites are a novel class of membrane materials with unique properties enabling molecular sieving and affinity based separations. This thesis proposes some new concepts in zeolite membrane

  6. Zeolite H-BEA catalysed multicomponent reaction: One-pot ...

    Indian Academy of Sciences (India)

    attention because of their tunable acidity and the vari- ety of structures and pore dimensions. The other salient features of zeolite include their low cost and excel- lent thermal stability which make them economically and environmentally feasible.2 The use of zeolites as a catalyst is important in the development of clean tech-.

  7. FUNDAMENTALS AND APPLICATIONS OF PERVAPORATION THROUGH ZEOLITE MEMBRANES

    Science.gov (United States)

    Zeolite membranes are well suited for separating liquid-phase mixtures by pervaporation because of their molecular-sized pores and their hydrophilic/hydrophobic nature, and the first commercial application of zeolite membranes has been for dehydrating organics [1]. Because of ...

  8. A novel urea conductometric biosensor based on zeolite immobilized urease.

    Science.gov (United States)

    Kirdeciler, Salih Kaan; Soy, Esin; Oztürk, Seçkin; Kucherenko, Ivan; Soldatkin, Oleksandr; Dzyadevych, Sergei; Akata, Burcu

    2011-09-15

    A new approach was developed for urea determination where a thin film of silicalite and zeolite Beta deposited onto gold electrodes of a conductometric biosensor was used to immobilize the enzyme. Biosensor responses, operational and storage stabilities were compared with results obtained from the standard membrane methods for the same measurements. For this purpose, different surface modification techniques, which are simply named as Zeolite Membrane Transducers (ZMTs) and Zeolite Coated Transducers (ZCTs) were compared with Standard Membrane Transducers (SMTs). Silicalite and zeolite Beta with Si/Al ratios 40, 50 and 60 were used to modify the conductometric electrodes and to study the biosensor responses as a function of changing zeolitic parameters. During the measurements using ZCT electrodes, there was no need for any cross-linker to immobilize urease, which allowed the direct evaluation of the effect of changing Si/Al ratio for the same type of zeolite on the biosensor responses for the first time. It was seen that silicalite and zeolite Beta added electrodes in all cases lead to increased responses with respect to SMTs. The responses obtained from ZCTs were always higher than ZMTs as well. The responses obtained from zeolite Beta modified ZMTs and ZCTs increased as a function of increasing Si/Al ratio, which might be due to the increased hydrophobicity and/or the acid strength of the medium. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Generalized synthesis of mesoporous shells on zeolite crystals

    KAUST Repository

    Han, Yu

    2010-12-30

    A simple and generalized synthetic approach is developed for creating mesoporous shells on zeolite crystals. This method allows for the tailoring of thickness, pore size, and composition of the mesoporous shell, and can be applied to zeolites of various structures, compositions, and crystal sizes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Adsorption selectivity of benzene and propene mixtures for various zeolites

    NARCIS (Netherlands)

    Ban, S.|info:eu-repo/dai/nl/304837288; van Laak, A.N.C.|info:eu-repo/dai/nl/304833223; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; van der Eerden, J.P.J.M.|info:eu-repo/dai/nl/068420471; Vlugt, T.J.H.|info:eu-repo/dai/nl/205040187

    2007-01-01

    The nine-site benzene model of Zhao et al. (J. Phys. Chem. B 2005, 109, 5368-5374) has been used to systematically study the adsorption of benzene, propene, and benzene-propene mixtures in zeolites mordenite, Y, , silicalite, and MCM22. Interaction parameters for the benzene-zeolite interactions

  11. Early cosmology constrained

    Energy Technology Data Exchange (ETDEWEB)

    Verde, Licia; Jimenez, Raul [Institute of Cosmos Sciences, University of Barcelona, IEEC-UB, Martí Franquès, 1, E08028 Barcelona (Spain); Bellini, Emilio [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Pigozzo, Cassio [Instituto de Física, Universidade Federal da Bahia, Salvador, BA (Brazil); Heavens, Alan F., E-mail: liciaverde@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: cpigozzo@ufba.br, E-mail: a.heavens@imperial.ac.uk, E-mail: raul.jimenez@icc.ub.edu [Imperial Centre for Inference and Cosmology (ICIC), Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2017-04-01

    We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω{sub MR} < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N {sub eff} < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r {sub s} = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r {sub s} = 150 ± 5 Mpc.

  12. Treatments of reverse osmosis concentrate using natural zeolites

    Directory of Open Access Journals (Sweden)

    Taherifar Hossein

    2015-06-01

    Full Text Available The purpose of the current study is to experimentally investigate the reduction of sodium adsorption ratio (SAR from a concentrated stream of reversed osmosis (RO using natural zeolites. In order to reduce the salinity of solution, experiments were carried out using zeolites of varying concentration, pretreatment of adsorbents, and the addition of Ethylenediaminetetraacetic acid (EDTA. The results show that both zeolites can be used in an RO brine treatment; however, Rhyolitic tuff is more effective than clinoptilolite for the reduction of water salinity. The experiments show that Rhyolitic tuff decreases salinity of RO concentrate to nearly one – third of the initial value. Statistical analyses show that the effect of zeolite concentration is negligible. Furthermore, the addition of EDTA and pretreatment of zeolite increase the SAR values.

  13. Tailoring the porosity of hierarchical zeolites by carbon-templating

    DEFF Research Database (Denmark)

    Zhu, Kake; Egeblad, Kresten; Christensen, Claus H.

    2008-01-01

    We report the synthesis and characterization of a series of hierarchical porous zeolite single crystal materials with a range of porosities made available by carbon-templating using differently-sized carbon particles as templates for the additional non-micropore porosity. The materials were...... prepared by adsorption of the required zeolite synthesis gel components onto various commercially available carbon black powders followed by crystallization of the zeolite crystals in the presence of the inert carbon matrix and subsequent removal of the carbon particles embedded in the zeolite crystals...... by combustion. It is shown that the additional porosity of the hierarchical zeolites can be tailored by encapsulation of the differently-sized carbon particles during crystallization....

  14. Synthesis and catalytic applications of combined zeolitic/mesoporous materials

    Directory of Open Access Journals (Sweden)

    Jarian Vernimmen

    2011-11-01

    Full Text Available In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials.

  15. Fly ash based zeolitic pigments for application in anticorrosive paints

    International Nuclear Information System (INIS)

    Shaw, Ruchi; Tiwari, Sangeeta

    2016-01-01

    The purpose of this work is to evaluate the utilization of waste fly ash in anticorrosive paints. Zeolite NaY was synthesized from waste fly ash and subsequently modified by exchanging its nominal cation Na + with Mg 2+ and Ca 2+ ions. The metal ion exchanged zeolite was then used as anticorrosive zeolitic pigments in paints. The prepared zeolite NaY was characterized using X-Ray diffraction technique and Scanning electron microscopy. The size, shape and density of the prepared fly ash based pigments were determined by various techniques. The paints were prepared by using fly ash based zeolitic pigments in epoxy resin and the percentages of pigments used in paints were 2% and 5%. These paints were applied to the mild steel panels and the anticorrosive properties of the pigments were assessed by the electrochemical spectroscopy technique (EIS).

  16. Note on constrained cohomology

    International Nuclear Information System (INIS)

    Delduc, F.; Maggiore, N.; Piguet, O.; Wolf, S.

    1996-08-01

    The cohomology of the BRS operator corresponding to a group of rigid symmetries is studied in a space of local field functionals subjected to a condition of gauge invariance. We propose a procedure based on a filtration operator counting the degree in the infinitesimal parameters of the rigid symmetry transformations. An application to Witten's topological Yang-Mills theory is given. (author). 18 refs

  17. Theoretical investigation of layered zeolite frameworks: Interaction between IPC-1P layers derived from zeolite UTL

    Czech Academy of Sciences Publication Activity Database

    Grajciar, L.; Bludský, Ota; Roth, Wieslaw Jerzy; Nachtigall, P.

    2013-01-01

    Roč. 204, Apr 15 (2013), s. 15-21 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : layered zeolites * density functional theory * hydrogen bonding * structure Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.309, year: 2013

  18. Adsorption of CO2 in FAU zeolites: Effect of zeolite composition

    Czech Academy of Sciences Publication Activity Database

    Thang, H. V.; Grajciar, L.; Nachtigall, P.; Bludský, Ota; Areán, C. O.; Frýdová, E.; Bulánek, R.

    2014-01-01

    Roč. 227, May 15 (2014), s. 50-56 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 Keywords : DFT/CC * CO2 * carbon capture and storage * zeolite * adsorption calorimetry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  19. Q-deformed systems and constrained dynamics

    International Nuclear Information System (INIS)

    Shabanov, S.V.

    1993-01-01

    It is shown that quantum theories of the q-deformed harmonic oscillator and one-dimensional free q-particle (a free particle on the 'quantum' line) can be obtained by the canonical quantization of classical Hamiltonian systems with commutative phase-space variables and a non-trivial symplectic structure. In the framework of this approach, classical dynamics of a particle on the q-line coincides with the one of a free particle with friction. It is argued that q-deformed systems can be treated as ordinary mechanical systems with the second-class constraints. In particular, second-class constrained systems corresponding to the q-oscillator and q-particle are given. A possibility of formulating q-deformed systems via gauge theories (first-class constrained systems) is briefly discussed. (orig.)

  20. Removal of pyridine and quinoline by bio-zeolite composed of mixed degrading bacteria and modified zeolite

    International Nuclear Information System (INIS)

    Bai Yaohui; Sun Qinghua; Xing Rui; Wen Donghui; Tang Xiaoyan

    2010-01-01

    In the process of the biodegradation of pyridine and quinoline, ammonium is often generated because of the transformation of N from pyridine and quinoline. Zeolite has been proven to be an effective sorbent for the removal of the ammonium. The natural zeolite can be modified to be the macroporous carrier in the biological wastewater treatment process. In this study, a specific bio-zeolite composed of mixed bacteria (a pyridine-degrading bacterium and a quinoline-degrading bacterium) and modified zeolite was used for biodegradation and adsorption in two types of wastewater: sterile synthetic and coking wastewater. The experimental results indicated that pyridine and quinoline could be degraded simultaneously by the mixed bacteria. Furthermore, NH 4 + -N transformed from pyridine and quinoline could be removed by the modified zeolite. In addition, the bacterial community structures of the coking wastewater and the bio-zeolite were monitored by the amplicon length heterogeneity polymerase-chain reaction (LH-PCR) technique. Both LH-PCR results and scanning electron microscope (SEM) observations indicated that the microorganisms, including BW001 and BW003, could be easily attached on the surface of the modified zeolite and that the bio-zeolite could be used in the treatment of wastewater containing pyridine and/or quinoline.

  1. Constraining neutrinoless double beta decay

    International Nuclear Information System (INIS)

    Dorame, L.; Meloni, D.; Morisi, S.; Peinado, E.; Valle, J.W.F.

    2012-01-01

    A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum-rules (MSR). We show how these theories may constrain the absolute scale of neutrino mass, leading in most of the cases to a lower bound on the neutrinoless double beta decay effective amplitude.

  2. Adsorption of Indigo Carmine Dye Using Cetyltrimethylammonium Bromide (CTAB) Surfactant Modified Zeolite

    OpenAIRE

    Fauziyah, Nurul; Sriatun, Sriatun; Pardoyo, Pardoyo

    2015-01-01

    Research of indigo carmine dye adsorption using natural zeolite modified by cetyltrimethylammonium bromide (CTAB) surfactant has been done. The purpose of this study was to modify the natural zeolite using CTAB surfactant and to determine its ability on the adsorption of indigo carmine dye. The stages of the study included the activation of zeolites, modifying zeolites using CTAB surfactant and adsorption test of indigo carmine dye. The results showed that the zeolites could be modified by CT...

  3. Altering bio-oil composition by catalytic treatment of pinewood pyrolysis vapors over zeolites using an auger - packed bed integrated reactor system

    Directory of Open Access Journals (Sweden)

    Vamshi Krishna Guda

    2016-09-01

    Full Text Available Pine wood pyrolysis vapors were catalytically treated using Zeolite catalysts. An auger fed reactor was used for the pinewood pyrolysis while a packed bed reactor mounted on the top of the auger reactor housed the catalyst for the treatment of pinewood pyrolytic vapors. The pyrolytic vapors produced at 450 oC were passed through zeolite catalysts maintained at 425 oC at a weight hourly space velocity (WHSV of 12 h-1. Five zeolites, including ZSM-5, mordenite, ferrierite, Zeolite-Y, and Zeolite-beta (all in H form, were used to study the effect of catalyst properties such as acidity, pore size, and pore structure on catalytic cracking of pinewood pyrolysis vapors. Product bio-oils were analyzed for their chemical composition using GC-MS, water content, density, viscosity, acid value, pH, and elemental compositions. Thermogravimetric analysis (TGA was performed to analyze the extent of coking on zeolite catalysts. Application of catalysis to biomass pyrolysis increased gas product yields at the expense of bio-oil yields. While all the zeolites deoxygenated the pyrolysis vapors, ZSM-5 was found to be most effective. The ZSM-5 catalyzed bio-oil, rich in phenolics and aromatic hydrocarbons, was less viscous, had relatively lower acid number and high pH, and possessed oxygen content nearly half that of un-catalyzed bio-oil. Brønsted acidity, pore size, and shape-selective catalysis of ZSM-5 catalyst proved to be the determining factors for its activity. TGA results implied that the pore size of catalysts highly influenced coking reactions. Regeneration of the used catalysts was successfully completed at 700 oC.

  4. [Zeolite catalysis in conversion of cellulosics

    Energy Technology Data Exchange (ETDEWEB)

    Tsao, G.T.

    1992-12-31

    To transform biomass into fermentable substrate for yeast, we are using zeolites instead of enzymes to catalyze the two bottleneck reactions in biomass conversion, xylose isomerization and ceuobiose hydrolysis. The experimental results on these reactions carried out over various zeolites and other catalysts are presented herein. The advantages and disadvantages of using these catalysts over enzymes are also discussed. Heterogeneous solid catalysts other than zeolites has been employed for cellobiose-to-glucose hydrolysis. The size and shape selectivity that makes zeoutes unique for some reactions can add diffusional hindrance. We have spent some time screening various known solid acidic catalysts. We report that a class of cationic ion exchange resins in the acidified form (e.g. Amberlite) has worked well as an acidic catalyst in hydrolyzing cellobiose to glucose. Our experimental results, together with those obtained from a homogeneous acid catalyst (e.g. sulfuric acid) for comparison are provided. Having succeeded in finding an alternative solid acid catalyst for hydrolysis, we explored other solid resin or other homogeneous but non-enzyme catalyst to carry out the xylose-to-xylulose isomerization. A fairly extensive search has been made. We explored the use of sodium aluminates in the homogeneous phase isomerization of glucose to fructose and obtained a very high conversion of glucose to fructose with the final mixture containing 85% of fructose instead of the common 45%. Fructose apparently complexes with aluminates, and its equilibrium concentration is shifted to considerably higher values than permitted by simple glucose/fructose equilibrium. We have recently found a number of catalysts capable of promoting isomerization between aldoses and ketoses. One solid resin, known as polyvinyl pyridine (PVP), is able to convert xylose to xylulose at a pH below 7. Our usage of alternative isomerization catalysts, including PVP, are described.

  5. [Zeolite catalysis in conversion of cellulosics

    Energy Technology Data Exchange (ETDEWEB)

    Tsao, G.T.

    1992-01-01

    To transform biomass into fermentable substrate for yeast, we are using zeolites instead of enzymes to catalyze the two bottleneck reactions in biomass conversion, xylose isomerization and ceuobiose hydrolysis. The experimental results on these reactions carried out over various zeolites and other catalysts are presented herein. The advantages and disadvantages of using these catalysts over enzymes are also discussed. Heterogeneous solid catalysts other than zeolites has been employed for cellobiose-to-glucose hydrolysis. The size and shape selectivity that makes zeoutes unique for some reactions can add diffusional hindrance. We have spent some time screening various known solid acidic catalysts. We report that a class of cationic ion exchange resins in the acidified form (e.g. Amberlite) has worked well as an acidic catalyst in hydrolyzing cellobiose to glucose. Our experimental results, together with those obtained from a homogeneous acid catalyst (e.g. sulfuric acid) for comparison are provided. Having succeeded in finding an alternative solid acid catalyst for hydrolysis, we explored other solid resin or other homogeneous but non-enzyme catalyst to carry out the xylose-to-xylulose isomerization. A fairly extensive search has been made. We explored the use of sodium aluminates in the homogeneous phase isomerization of glucose to fructose and obtained a very high conversion of glucose to fructose with the final mixture containing 85% of fructose instead of the common 45%. Fructose apparently complexes with aluminates, and its equilibrium concentration is shifted to considerably higher values than permitted by simple glucose/fructose equilibrium. We have recently found a number of catalysts capable of promoting isomerization between aldoses and ketoses. One solid resin, known as polyvinyl pyridine (PVP), is able to convert xylose to xylulose at a pH below 7. Our usage of alternative isomerization catalysts, including PVP, are described.

  6. Epoxy Nanocomposites Containing Zeolitic Imidazolate Framework-8.

    Science.gov (United States)

    Liu, Cong; Mullins, Michael; Hawkins, Spencer; Kotaki, Masaya; Sue, Hung-Jue

    2018-01-10

    Zeolitic imidazole framework-8 (ZIF-8) is utilized as a functional filler and a curing agent in the preparation of epoxy nanocomposites. The imidazole group on the surface of the ZIF-8 initiates epoxy curing, resulting in covalent bonding between the ZIF-8 crystals and epoxy matrix. A substantial reduction in dielectric constant and increase in tensile modulus were observed. The implication of the present study for utilization of metal-organic framework to improve physical and mechanical properties of polymeric matrixes is discussed.

  7. Temperature dependence of Raman spectroscopy of molecular iodine trapped in zeolite crystals

    Science.gov (United States)

    Guo, Wenhao; Wang, Dingdi; Hu, Juanmei; Tang, Zikang; Du, Shengwang

    2012-02-01

    Molecular iodine has been pursued for many practical applications, such as molecular clock, molecule-based quantum information processing, due to its narrow-linewidth hyperfine optical transitions. But because of its low vapor pressure, the experimental setup employing a free-space-based iodine vapor cell is very space-consuming. Recently, it is reported that the iodine molecule can be loaded into the channels of zeolite crystals, the density there could be orders improved and its space orientation can be precisely controlled. It may drastically reduce the size of molecular iodine experiment setup, and have many potential applications in microchip technology. We have studied the Raman spectroscopy of iodine molecule confined in zeolite crystals, AlPO4-5 (AFI) and AlPO4-11 (AEL), under different temperatures. The results show that in AEL, where the molecules are intensely confined, the ground vibrational states are close to that of an ideal 1D harmonic oscillator, while in AFI, where the molecules have a bit more freedom, they vibrate like in the free space, but with a loosened spring. And we come up a reasonable theoretical model to explain the Raman width dependence on temperature for these systems

  8. Distribution of metal and adsorbed guest species in zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  9. Positron annihilation in modified zeolites LTA and 13X

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Prieto, A.; Garcia-Sosa, I.; Jimenez-Becerril, J. [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Col. Escandon, Del. M. Hidalgo, Mexico D. F., c. p. 11801 (Mexico); Lopez-Castanares, R.; Olea-Cardoso, O. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Paseo Tollocan esquina paseo Tollocan, esquina paseo Colon, Toluca, c. p. 50120, Estado de Mexico (Mexico)

    2007-07-01

    The pick-off annihilation lifetimes of o -Ps, {tau}{sub po}, in dehydrated Co{sup 2+} and Mn{sup 2+} exchanged zeolites LTA, in dehydrated Co{sup 2+} exchanged zeolite 13X, and in dehydrated Na{sup +} zeolites LTA and 13X, are estimated. Although {tau}{sub po} can be estimated from the lifetime spectra of the cation exchanged zeolites LTA and 13X, this lifetime can not be estimated from those spectra of Na{sup +} zeolite LTA unambiguously. The estimated pick-off lifetimes due to the annihilation of o-Ps in the internal walls of the zeolites are systematically lower than the average lifetime of p-Ps and o-Ps in vacuum {tau}{sub a}=0.5 ns. Since the pick-off process of o-Ps occurs particularly on the internal cavity walls of dehydrated zeolites, the replacement of {tau}{sub a} by {tau}{sub po} within the classical model of Tao-Eldrup to calculate cavity radius should provide more realistic cavity radii of these porous materials than when using {l_brace}{tau}{sub a}{r_brace}. This suggestion is supported by previous and present results. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Introduction to chemistry of crystalline zeolites and its applications

    International Nuclear Information System (INIS)

    Lobo Cabezas, Raul Francisco

    2006-01-01

    Establishes the zeolites as the most important group of solid acids and its relation to the contemporaneous chemical industry. It describes that zeolites are used in the following applications: refineries, chemicals/petrochemicals, environmental chemistry, separation of gas, adsorbent ia and ionic exchange in water purification in mineral processes, medicine and agricultural industry. Zeolites are defined as crystalline aluminium silicates with a compound structure of interconnected tetrahedrons. It mentions the key components in zeolites structure. It focuses that structural basic unity of the zeolite is the tetrahedron and compound structural unities are: cells and columns. Besides, it describes that pore system defines a lot of all its properties; but chemical composition affects them. Composition and properties of zeolites are established: adsorption, molecular sieves, acidity, selectivity, transition state in the hydrocarbon's chemistry. It concludes that the newer application of zeolite is in oxidations: Titanium-Silicate-1; production of propylene's oxide using peroxide of hydrogen as oxidizing. The catalysis is an active area of research, and the most popular areas are related to chemicals and the environment [es

  11. Zeolite-catalyzed hydrogenation of carbon dioxide and ethene.

    Science.gov (United States)

    Chan, Bun; Radom, Leo

    2008-07-30

    Ab initio molecular orbital theory and density functional theory calculations have been used to study the three-stage zeolite-catalyzed hydrogenation of CO2 to methanol and the hydrogenation of C2H 4 to ethane, with the aim of designing an effective zeolite catalyst for these reactions. Both Brønsted acid (XH) and alkali metal (XM) sites in model zeolites (-X-Al-XH- or -X-Al-XM-) have been examined. It is found that appropriately designed zeolites can provide excellent catalysis for these reactions, particularly for the hydrogenation of CO2, HCO2H and CH2O, with uncatalyzed barriers of more than 300 kJ mol(-1) being reduced to as little as 17 kJ mol(-1) (in the case of CH2O). The reaction barrier depends on the acidity of the XH moiety or the nature of the metal cation M in the XM moiety, and the basicity of the adjacent X group in the catalyst. For a catalyst based on alkali metal zeolites (XM), the catalytic activity is relatively insensitive to the nature of X in the XM group. As a result, the catalytic activity for these types of zeolites increases as X becomes more basic. We propose that alkali metal zeolites with Ge and N incorporated into the framework could be very effective catalysts for hydrogenation processes.

  12. CoX zeolites and their exchange with deuterium

    International Nuclear Information System (INIS)

    Novakova, J.; Kubelkova, L.; Jiru, P.

    1976-01-01

    An analysis of the gaseous phase using a mass spectrometer and analysis of the solid phase using an infrared spectrophotometer was made to investigate the deuterium exchange with hydrogen mostly bound in hydroxyl groups of zeolites CoX(21 and 47%) and NaX. It was found that with the increasing amount of cobalt ions the number of exchangeable hydrogens of the zeolite increases; the respective types of the hydrogen are discussed with respect to the particular dehydration temperatures. The rate of the D 2 +OH exchange is substantially faster with the CoX than with the NaX zeolite, and exhibits a decrease with increasing dehydration. On the other hand, the rate of D 2 +H 2 exchange without zeolite hydrogen incorporation, catalyzed by CoX zeolites, increases with increasing dehydration. The increased activation of gaseous hydrogen molecules is related to the presence in the zeolite of cobalt ions whose properties change during dehydration with the change in their environment. Hydroxyl groups of the CoX zeolites are not equivalent during the exchange; the hydroxyl hydrogens of the 3740 cm -1 band are exchanged more slowly than are the other hydrogens. (author)

  13. Distribution of metal and adsorbed guest species in zeolites

    International Nuclear Information System (INIS)

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes 129 Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of 129 Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, 129 Xe NMR is insensitive to fine structural details at room temperature

  14. Fabrication of 6FDA-durene membrane incorporated with zeolite T and aminosilane grafted zeolite T for CO2/CH4 separation

    Science.gov (United States)

    Jusoh, Norwahyu; Fong Yeong, Yin; Keong Lau, Kok; Shariff, Azmi Mohd

    2017-08-01

    In the present work, zeolite T and aminosilane grafted zeolite T are embedded into 6FDA-durene polyimide phase for the fabrication of mixed matrix membranes (MMMs). FESEM images demonstrated that the improvement of interfacial adhesion between zeolite and polymer phases in MMM loaded with aminosilane grafted zeolite T was not significant as compared to zeolite T/6FDA-durene MMM. From the gas permeation test, CO2/CH4 selectivity up to 26.4 was achieved using MMM containing aminosilane grafted zeolite T, while MMM loaded with ungrafted zeolite T showed CO2/CH4 selectivity of 19.1. In addition, MMM incorporated with aminosilane grafted zeolite T particles successfully lies on Robeson upper bound 2008, which makes it an attractive candidate for CO2/CH4 separation.

  15. Sorption of 60 Co in natural zeolite (clinoptilolite)

    International Nuclear Information System (INIS)

    Hernandez B, E.

    1996-01-01

    A Mexican zeolite (clinoptilolite) from Taxco, Guerrero, was partially stabilized with sodium cations. Radioactive Cobalt ( 60 Co) was used to study the Co 2+ sorption in the stabilized zeolite (Na + ). It was found that sorption in general does not favour the diffusion of cobalt between framework, it explains because of it is a natural zeolite and its composition heterogeneous decrease its exchange capacity by the generated competence to the existence other type of exchange ions. The cobalt retention reached the highest level, around 0.408 m eq Co 2+ /g in the Na-Clinoptilolite. The crystallinity of the aluminosilicates was maintained during experiments, it was verified by XRD patterns. (Author)

  16. Zeolite-catalyzed isomerization of tetroses in aqueous medium

    DEFF Research Database (Denmark)

    Shunmugavel, Saravanamurugan; Riisager, Anders

    2014-01-01

    The isomerization of erythrose (ERO) was studied in water over commercially available large-pore zeolites such as, e.g. H-Y, H-USY and H-beta. Among the employed zeolites, H-USY(6) was found to efficiently isomerize the sugar yielding 45 % erythrulose (ERU), 42 % ERO and 3 % of the epimer threose...... in water. Hence, the results demonstrate water to be a preferred solvent compared to lower alcohols for zeolite-catalyzed tetrose isomerization, which is opposite to what previously have been found for analogous pentose and hexose isomerization. A reuse study revealed further that H-USY(6) could be applied...

  17. Zeolite-catalyzed biomass conversion to fuels and chemicals

    DEFF Research Database (Denmark)

    Taarning, Esben; Osmundsen, Christian Mårup; Yang, Xiaobo

    2011-01-01

    Heterogeneous catalysts have been a central element in the efficient conversion of fossil resources to fuels and chemicals, but their role in biomass utilization is more ambiguous. Zeolites constitute a promising class of heterogeneous catalysts and developments in recent years have demonstrated...... their potential to find broad use in the conversion of biomass. In this perspective we review and discuss the developments that have taken place in the field of biomass conversion using zeolites. Emphasis is put on the conversion of lignocellulosic material to fuels using conventional zeolites as well...

  18. Hierarchical zeolites from class F coal fly ash

    Science.gov (United States)

    Chitta, Pallavi

    Fly ash, a coal combustion byproduct is classified as types class C and class F. Class C fly ash is traditionally recycled for concrete applications and Class F fly ash often disposed in landfills. Class F poses an environmental hazard due to disposal and leaching of heavy metals into ground water and is important to be recycled in order to mitigate the environmental challenges. A major recycling option is to reuse the fly ash as a low-cost raw material for the production of crystalline zeolites, which serve as catalysts, detergents and adsorbents in the chemical industry. Most of the prior literature of fly ash conversion to zeolites does not focus on creating high zeolite surface area zeolites specifically with hierarchical pore structure, which are very important properties in developing a heterogeneous catalyst for catalysis applications. This research work aids in the development of an economical process for the synthesis of high surface area hierarchical zeolites from class F coal fly ash. In this work, synthesis of zeolites from fly ash using classic hydrothermal treatment approach and fusion pretreatment approach were examined. The fusion pretreatment method led to higher extent of dissolution of silica from quartz and mullite phases, which in turn led to higher surface area and pore size of the zeolite. A qualitative kinetic model developed here attributes the difference in silica content to Si/Al ratio of the beginning fraction of fly ash. At near ambient crystallization temperatures and longer crystallization times, the zeolite formed is a hierarchical faujasite with high surface area of at least 360 m2/g. This work enables the large scale recycling of class F coal fly ash to produce zeolites and mitigate environmental concerns. Design of experiments was used to predict surface area and pore sizes of zeolites - thus obviating the need for intense experimentation. The hierarchical zeolite catalyst supports tested for CO2 conversion, yielded hydrocarbons

  19. Performance Evaluations of Ion Exchanged Zeolite Membranes on Alumina Supports

    Energy Technology Data Exchange (ETDEWEB)

    Bhave, Ramesh R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jubin, Robert Thomas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Spencer, Barry B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nair, Sankar [Georgia Inst. of Technology, Atlanta, GA (United States)

    2017-08-27

    This report describes the synthesis and evaluation of molecular sieve zeolite membranes to separate and concentrate tritiated water (HTO) from dilute HTO-bearing aqueous streams. In the first phase of this effort, several monovalent and divalent cation-exchanged silico alumino phosphate (SAPO-34) molecular sieve zeolite membranes were synthesized on disk supports and characterized with gas and vapor permeation measurements. In the second phase, Linde Type A (LTA) zeolite membranes were synthesized in disk and tubular supports. The pervaporation process performance was evaluated for the separation and concentration of tritiated water.

  20. Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Wang, Feng

    2014-01-01

    With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high...... zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50% conversion of ethanol with 98...

  1. Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Wang, Feng

    2014-01-01

    With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite‐1 is reported and their high...... zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2–3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98...

  2. Method of preparing sodalite from chloride salt occluded zeolite

    Science.gov (United States)

    Lewis, M.A.; Pereira, C.

    1997-03-18

    A method is described for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistant sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1000 K to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

  3. Nanomodified natural zeolite as a fertilizer of prolonged activity

    Directory of Open Access Journals (Sweden)

    G. Tsintskaladze

    2016-09-01

    Full Text Available Natural zeolites of sedimentary origin are widely used in agriculture both as individual fertilizer and a mix of mineral and organic fertilizers. Natural zeolites are crystalline nanoporous hydrated aluminosilicates. Fertilizer of prolonged activity enriched with macro- and microelements is obtained by fusing zeolite with dehydrated ammonium using nanotechnological method of modification. The structure and some physical and chemical properties of a novel nanomaterial were studied by the methods of X-ray diffraction, IR-spectroscopy, absorption and thermal analysis. It was shown that the obtained fertilizer may be used in both protected and open grounds.

  4. Encapsulation of noble gas in zeolites

    International Nuclear Information System (INIS)

    Dorea, A.

    1987-04-01

    The noble gases neon, argon, krypton and xenon were encapsulated hydrothermally as pure gases as well as in the form of mixtures in type A zeolite of various cationic compositions. As opposed to the starting material the encapsulates are X-ray amorphous and posess a very small specific surface area. Irrespective of the thermal pretreatment of the zeolites the optimal loading occured within a certain temperature window. The amount of gas trapped was essentially a function of the fixation pressure. Within the pressure range 50-2200 bar the obtained loading was independent from the type of noble gas. When mixtures of noble gases were encapsulated a small enrichment of the heavier noble gas, caused by kinetic and thermodynamic effects, was observed. The thermal stability of the encapsulates was found to be very high. Even at temperatures as high as 750 0 C a recrystallization to anorthite was only observed after practically all the trapped gas had been released. Experiments destined to clarify the mechanism of gas leckage at temperatures below 750 0 C suggest a diffusion controlled mechanism described by a √t law. Even at loadings of 45 ml/(STP) Kr/g the leckage predicted under conditions as expected during longterm storage of Kr-85 is extremely small. Kinetic data demonstrate that the gas is not trapped in the form of agglomerates but rather exists homogeneously distributed within the encapsulate. This result is substantiated by electron beam microanalysis. (orig./RB) [de

  5. Multicolor photoluminescence in ITQ-16 zeolite film

    KAUST Repository

    Chen, Yanli

    2016-09-07

    Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence of Ge atoms. Various intrinsic defects of ITQ-16 films were fully studied through photoluminescence and FTIR characterizations. It was found that both the as-synthesized and calcined ITQ-16 films displayed multicolor photoluminescence including ultraviolet, blue, green and red emissions by exciting upon appropriate wavelengths. The results indicate that Si―OH and non-bridging oxygen hole centers(NBOHCs) are responsible for the origin of green and red emissions at 540―800 nm, while according to a variety of emission bands of calcined ITQ-16 film, blue emission bands at around 446 and 462 nm are attributed to peroxy free radicals(≡SiO2), ultraviolet emissions ranging from 250 nm to 450 nm are suggested originating from a singlet-to-triplet transition of two-fold-coordinated Si and Ge, respectively. © 2016, Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH.

  6. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    Science.gov (United States)

    Nicholas, Christopher P; Boldingh, Edwin P

    2013-12-17

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  7. Reaction Mechanism and Deactivation Pathways in Zeolite catalyzed Isobutane/2-Butene Alkylation

    OpenAIRE

    Feller, Andreas

    2007-01-01

    In this thesis, the isobutane/2-butene alkylation was studied on lanthanum-exchanged zeolite X in a CSTR-type slurry reactor. Catalysts with a high concentration of strong Brønsted acid sites and a high Brønsted to Lewis acid site ratio exhibited higher active catalytic lifetimes than samples with lower ratios. Isobutane self-alkylation activity was also increasing with increasing Brønsted/Lewis ratio. The integral productivity of the catalysts was found to be independent of the butene space ...

  8. Carbon Dioxide Adsorption on a 5A Zeolite Designed for CO2 Removal in Spacecraft Cabins

    Science.gov (United States)

    Mulloth, Lila M.; Finn, John E.

    1998-01-01

    Carbon dioxide adsorption data were obtained for a 5A zeolite manufactured by AlliedSignal Inc. (Des Plaines, Illinois). The material is planned for use in the Carbon Dioxide Removal Assembly (CDRA) for U.S. elements of the International Space Station. The family of adsorption isotherms covers a temperature range of O to 250 C, and a pressure range of 0.001 to 800 torr. Coefficients of the Toth equation are fit to the data. Isosteric heats of adsorption are derived from the equilibrium loading data.

  9. Lightweight cryptography for constrained devices

    DEFF Research Database (Denmark)

    Alippi, Cesare; Bogdanov, Andrey; Regazzoni, Francesco

    2014-01-01

    Lightweight cryptography is a rapidly evolving research field that responds to the request for security in resource constrained devices. This need arises from crucial pervasive IT applications, such as those based on RFID tags where cost and energy constraints drastically limit the solution...... complexity, with the consequence that traditional cryptography solutions become too costly to be implemented. In this paper, we survey design strategies and techniques suitable for implementing security primitives in constrained devices....

  10. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Alejandro, Serguei [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Núcleo de Energías Renovables (F. Ingeniería), Universidad Católica de Temuco, Rudecindo Ortega 02950, Temuco (Chile); Valdés, Héctor, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Manéro, Marie-Hélène [Université de Toulouse (France); INPT, UPS (France); Laboratoire de Génie Chimique, 4, Allée Emile Monso, F–31030 Toulouse (France); CNRS (France); Laboratoire de Génie Chimique, F–31030 Toulouse (France); Zaror, Claudio A. [Departamento de Ingeniería Química (F. Ingeniería), Universidad de Concepción, Concepción, Correo 3, Casilla 160–C (Chile)

    2014-06-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

  11. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    International Nuclear Information System (INIS)

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A.

    2014-01-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity

  12. Kr atoms and their clustering in zeolite A

    CERN Document Server

    Lim, W T; Jung, K J; Heo, N H

    2001-01-01

    The positions of Kr atoms encapsulated in the molecular-dimensioned cavities of fully dehydrated zeolite A of unit-cell composition Cs sub 3 Na sub 8 HSi sub 1 sub 2 Al sub 1 sub 2 O sub 4 sub 8 (Cs sub 3 -A) have been determined. Cs sub 3 -A was exposed to 1025 atm of krypton gas at 400 .deg. C for four days, followed by cooling at pressure to encapsulate Kr atoms. The resulting crystal structure of Cs sub 3 -A(6Kr) (a=12.247(2) A, R sub 1 =0.078, and R sub 2 =0.085) has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(1) .deg. C and 1 atm. In the crystal structure of Cs sub 3 -A(6Kr), six Kr atoms per unit cell are distributed over three crystallographically distinct positions: each unit cell contains one Kr atom at Kr(1) on a threefold axis in the sodalite unit, three at Kr(2) opposite four-rings in the large cavity , and two at Kr(3) on threefold axes in the large cavity . Relatively strong interactions of Kr atoms at Kr(1) and Kr(3) with Na sup + ions of ...

  13. Current progress on zeolite membrane reactor for CO2 hydrogenation

    Science.gov (United States)

    Makertiharta, I. G. B. N.; Dharmawijaya, P. T.; Wenten, I. G.

    2017-01-01

    Carbon capture and storage via catalytic hydrogenation into methanol have been recognized as the most promising solution to not only global warming issue but also high fuel and methanol demand worldwide. However, methanol synthesis from CO2 involves equilibrium limited reaction that can be optimized using membrane reactor (MR). Among all selective membrane layer, the zeolite is the most promising material because it can selectively remove water and methanol from reaction mixture component, especially H2. To present a clear background of zeolite membrane reactor, this paper will bring the brief discussion on the recent progress towards utilization of zeolite membrane reactor for CO2 hydrogenation. The progress of selective layer used in said MR will be examined in detail. Critical issues related to zeolite membrane reactor will also be discussed to develop it further.

  14. Obtaining zeolite Y synthesized by hydrothermal treatment assisted by microwave

    International Nuclear Information System (INIS)

    Simoes, A.N.; Simoes, V.N.; Neiva, L.S.; Rodrigues, M.G.F.; Gama, L.; Oliveira, J. B.L.

    2011-01-01

    n search of new catalysts several man-made structures have been developed. The use of zeolites in catalysis is applied due to its ability to associate activity, selectivity and stability, the main conditions to have an effective catalyst. Thus, studies have been done on the hydrothermal synthesis of zeolites by microwave assisted, since the use of microwave radiation offers several advantages over conventional heating. In this context, this work aims to synthesis and characterization of zeolite Y via hydrothermal treatment in a microwave oven. The sample obtained was characterized by XRD, BET and SEM. XRD results showed the formation of zeolite Y in just 60 minutes. The sample showed high value of surface area, the latter being of 476.2 m² / g. The particles are agglomerated, but with a narrow distribution of size. (author)

  15. Ammoniacal nitrogen removal from groundwaters using natural and synthetic zeolites

    OpenAIRE

    Matsiyevska, Oksana; Chverenchuk, Andrii; Soprunko, Svitlana; Berezyuk, Roman; Pidlisny, Bogdan

    2013-01-01

    In article results of ammoniacal nitrogen occurrence ways into groundwaters analysis was represented. NH4+ removing effectivity from simulative solutions by natural (Sokyrnytsia minefield, Ukraine) and synthetic zeolites was compared.

  16. Catalytic Cracking of Used Palm Oil using Composite Zeolite

    International Nuclear Information System (INIS)

    Chang, W.H.; Tye, C.T.

    2013-01-01

    The rapid expansion of human society implies greater energy demand and environmental issues. In face of depletion energy resources, research is being carried out widely in order to convert the plant oil into biofuel. In this research, the production of liquid biofuels via catalytic cracking of used palm oil in the presence of composite zeolite was studied. The performance of composite zeolite of different properties in the reaction has been evaluated. The catalytic cracking reactions were carried out in a batch reactor at reaction temperature of 350 degree Celsius for an hour. In the present study, adjusting the ratio of meso porous coating to microporous zeolite and magnesium loading on composite zeolite catalyst were found to be able to increase the gasoline fraction and overall conversion of the reaction. (author)

  17. Solubilisation of dye-loaded zeolite L nanocrystals

    NARCIS (Netherlands)

    Devaux, A.; Popović, Z.; Bossart, O.; De Cola, L.; Kunzmann, A.; Calzaferri, G.

    2006-01-01

    Solubilisation of zeolite L nanocrystals in different solvents is reported. Grafting alkoxysilane derivatives with a hydrophobic part leads to transparent suspensions in non-polar solvents while modification with a positively charged complex leads to solubilisation in water.

  18. Characterization structural and morphology ZSM-5 zeolite by hydrothermal synthesis

    International Nuclear Information System (INIS)

    Silva, V.J.; Crispim, A.C.; Queiroz, M.B.; Laborde, H.M.; Rodrigues, M.G.F.; Menezes, R.R.

    2009-01-01

    Solid acids are catalytic materials commonly used in the chemical industry. Among these zeolites are the most important business processes including water treatment, gas separation, and cracking long hydrocarbon chains to produce high octane gasoline. Its synthesis, characterization and applications have been widely studied. The objective this study was to synthesize the ZSM-5 zeolite for future use in separation processes and catalysis. The zeolite ZSM-5 was prepared by hydrothermal synthesis at 170°C, using silica, deionized water and the director of structures (TPABr - tetrapropylammonium bromide). The materials were characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and semiquantitative chemical analysis by X ray fluorescence (XRF). According to the XRD was possible to observe the formation of ZSM-5 zeolite, with peaks intense and well defined. The SEM showed the formation of individual particles, clean, rounded shapes. (author)

  19. Iba of Zeolites Exchanged with Lithium for Co2 Retention

    Science.gov (United States)

    Andrade, E.; Alfaro, S.; Valenzuela, M. A.; Solis, C.; Zaval, E. P.; Rocha, M. F.; Cruz, J.; Pfeiffer, H.; Bosch, P.; Contreras, C.; Baptiste, J.

    2009-03-01

    A great concern on the global climatic change, partially due to industry CO2 expelled to the atmosphere, has motivated the search of new materials able to retain this gas. Clays, perovskites, zeolites and membranes have been utilized to trap the CO2. Zeolites are widely used as molecular sieves in different industrial processes related to gas purification or gas separation. Synthetic zeolites exchanged with lithium were prepared as potential material for CO2 retention. A NRA method using the 7Li (p,α)4He was performed in order to measure the the Li contents. With SEM-EDS the atomic concentrations of elements as C, Na, Si, Al, K, Ca, Fe, etc. were determined. Zeolites were also characterized by XRD.

  20. Moderate temperature zeolitic alternation in a cooling pyroclastic deposit

    International Nuclear Information System (INIS)

    Levy, S.S.; O'Neil, J.R.

    1984-01-01

    The locally zeolitized Topopah Spring Member of the Paintbrush Tuff, Yucca Mountain, Nevada, USA is part of a thick sequence of zeolitized pyroclastic units. Most of the zeolitized units are nonwelded tuffs that were altered during low temperature diagenesis, but the distribution and textural setting of zeolite (heulandite-clinoptilolite and smectite in the densely welded Topopah Spring tuff suggests that these hydrous minerals formed while the tuff was still cooling after pyroclastic emplacement and welding. The hydrous minerals are concentrated within a transition zone between devitrified tuff in the central part of the unit and underlying vitrophyre. Movement of liquid and convected heat along fractures from the devitrified tuff to the vitrophyre caused local devitrification and hydrous mineral crystallization. Oxygen isotope geothermometry of cogenetic quartz confirms the nondiagnetic moderate temperature origin of the hydrous minerals at temperatures of about 40 to 100 0 C, assuming a meteoric water source. 14 refs., 3 figs., 1 tab

  1. Microporous Cokes Formed in Zeolite Catalysts Enable Efficient Solar Evaporation

    KAUST Repository

    Wang, Jianjian

    2017-03-13

    Cokes are inevitably generated during zeolite-catalyzed reactions as deleterious side products that deactivate the catalyst. In this study, we in-situ converted cokes into carbons within the confined microporous zeolite structures and evaluated their performances as absorbing materials for solar-driven water evaporation. With a properly chosen zeolite, the cokederived carbons possessed ordered interconnected pores and tunable compositions. We found that the porous structure and the oxygen content in as-prepared carbons had important influences on their energy conversion efficiencies. Among various investigated carbon materials, the carbon derived from the methanol-to-olefins reaction over zeolite Beta gave the highest conversion efficiency of 72% under simulated sunlight with equivalent solar intensity of 2 suns. This study not only demonstrates the great potential of traditionally useless cokes for solar thermal applications but also provides new insights into the design of carbon-based absorbing materials for efficient solar evaporation.

  2. Solvation and Acid Strength Effects on Catalysis by Faujasite Zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Gounder, Rajamani P.; Jones, Andrew J.; Carr, Robert T.; Iglesia, Enrique

    2012-02-01

    reactivity by Na+ cations. Monomolecular isobutane cracking and dehydrogenation rate constants (per H+; 763 K), however, were higher on H-USY than CD-HUSY (by a factor of 1.4). Equilibrium constants for the formation of protonated methanol dimers via adsorption of gaseous methanol onto adsorbed methanol monomers, determined from kinetic studies of methanol dehydration to dimethyl ether (433 K), were also higher on H-USY than CD-HUSY (by a factor of 2.1). These larger constants predominantly reflect stronger dispersive interactions in H-USY, consistent with its smaller supercage voids that result from the occlusion of void space by extraframework Al (Alex) residues. These findings appear to clarify enduring controversies about the mechanistic interpretation of the effects of Na+ and Alex species on the catalytic reactivity of FAU zeolites. They also illustrate the need to normalize rates by the number of active sites instead of more convenient but less accurate structural proxies for such sites.

  3. Regioselective nitration of aromatic substrates in zeolite cages

    Indian Academy of Sciences (India)

    Unknown

    selective nitration with a nitrogen dioxide-oxygen-zeolite H-β/HY as a solid inorganic catalyst.14 Recently .... acetic anhydride/CCl4 with an isomer distribution of ortho 23, meta 1 and para 76%.18. Smith has shown that .... all the zeolites, except CaY, recovered mass balance was about 90%. 3.2c Nitration of toluene and ...

  4. Investigation of zeolites by solid state quadrapole NMR

    International Nuclear Information System (INIS)

    Janssen, R.

    1990-01-01

    The subject of this thesis is the NMR investigation of zeolites. The nature and properties of zeolites are discussed. Some of the basic priniples of NMR techniques on quadrupole nuclei are presented. A special technique, namely a two-dimensional nutation experiment is discussed in detail. The theory of the nutation experiment for quadrupole spin species with spin quantum number 3/2 as well as 5/2 is presented. For both spin spcies the theoretical spectra are compared with experimental results. It is also shown that the nutation expeirment can be performed with several pulse schemes. It is shown how phase-sensitive pure-absorption nutation spectra can be obtained and an NMR-probe is presented that is capable of performing NMR experiments at high (up to 500 degree C) temperatures. The two-dimensional nutation NMR technique has been applied to sodium cations in zeolite NaA. For this purpose a numbre of zeolite samples were prepared that contained different amounts of water. With the aid of nutation NMR the hydration of the zeolite can be studied and conclusions can be drawn about the symmetry of the surrounding of the sodium cations. With the aid of an extension of the nutation NMR experiment: Rotary Echo Nutation NMR, it is shown that in zeolite NaA, in various stages of hydration, the sodium cations or water molecules are mobile. Proof is given by means of high-temperature 23 Na-NMR that dehydrates zeolite NaA undergoes a phase transition at ca. 120 degree C. In a high-temperature NMR investigation of zeolite ZSM-5 it is shown that the sodium ions start to execute motions when the temperature is increased. (author). 198 refs.; 72 figs.; 6 tabs

  5. Zeolite and zeotype-catalysed transformations of biofuranic compounds

    DEFF Research Database (Denmark)

    Li, Hu; Yang, Song; Riisager, Anders

    2016-01-01

    ,5-furandicarboxylic acid can be obtained from hexoses and pentoses via selective dehydration and subsequent etherification, hydrogenation, oxidation reactions, which show great potential for industrial applications to replace petroleum-based chemicals and fuels. Zeolite and zeotype micro- and mesoporous materials...... introducing zeolite-catalysed hydrolysis of di-, oligo- and polysaccharides and isomerization reactions of monomeric sugars. Subsequently, the catalytic dehydration reactions of hexoses and pentoses to obtain HMF and furfural are reported. Particularly, a variety of reaction pathways towards upgrading...

  6. Pemanfaatan Zeolit Alam Untuk Pengeringan Karaginan Dengan Spray Dryer

    OpenAIRE

    M.H, Babar Priyadi; Afifi, Thufail Khoirul; Sasongko, Setia Budi

    2012-01-01

    The problem that will be faced in drying is quite high relative humidity, therefore carrageenan drying process using spray dryer with zeolite as humidity absorber becomes alternative option to achieve heat effectiveness of air dryer. The research is purposed to examine the effect of temperature and level of zeolite to relative humidity and product quality on carrageenan drying process. Spray dryer is a dryer used to produce powder material from feeds which have liquid and pasta form. The Resu...

  7. Synthesis of Zeolite Materials for Noble Gas Separation

    Energy Technology Data Exchange (ETDEWEB)

    Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rivera, O. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Wellons, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-02

    Microporous zeolite adsorbent materials are widely used as a medium for separating gases. Adsorbent gas separation systems can run at ambient temperature and require minimal pressure to flow the input gas stream across the adsorbent bed. This allows for low energy consumption relative to other types of separation systems. Specific zeolites also have a high capacity and selectivity for the gases of interest, leading to compact and efficient separation systems. These characteristics are particularly advantageous for the application of signatures detection for non-proliferation, which often requires portable systems with low power draw. Savannah River National Laboratory currently is the leader in using zeolites for noble gas sampling for non-proliferation detection platforms. However, there is a constant customer need for improved sampling capabilities. Development of improved zeolite materials will lead to improved sampling technology. Microwave-assisted and conventional hydrothermal synthesis have been used to make a variety of zeolites tailored for noble gas separation. Materials characterization data collected in this project has been used to help guide the synthesis of improved zeolite materials. Candidate materials have been down-selected based on highest available surface area, maximum overall capacity for gas adsorption and highest selectivity. The creation of improved adsorbent materials initiated in this project will lead to development of more compact, efficient and effective noble gas collectors and concentrators. The work performed in this project will be used as a foundation for funding proposals for further material development as well as possible industrial applications.

  8. Effects of Zeolite (Clinoptelolite on Performance Characteristics of

    Directory of Open Access Journals (Sweden)

    A Hassan Abadim

    2011-12-01

    Full Text Available A 70-days experiment was conducted to investigate the effects of natural zeolite (clinoptelolite on the performance of commercial laying hens. 288 Hy-Line W36 strain laying hens (50 weeks old were allotted to 6 dietary treatments including basal diet as control and basal diet supplemented with 1, 2, 3, 4 and 5% zeolite that were fed ad -libitum throughout the experiment. Experimental diets for the 6 treatments were prepared to be iso-caloric and iso-nitrogenous. A completely randomized design with six treatments, eight replicates of six birds per replicate was used at this experiment. Daily feed intake (DFI, feed conversion ratio (FCR, egg production, egg weight, egg white quality, eggshell quality (thickness and percentage and body weight changes were measured during the experiment. Results of this experiment showed that DFI, FCR, egg production and egg abnormality were not significantly (P>0.05 affected by zeolite supplementation. Zeolite supplementation significantly increased egg weight, eggshell thickness and live body weight gain of the hens. Dietary zeolite significantly decreased haugh unit of the eggs. In conclusion, natural zeolite significantly improved egg weight and eggshell quality, decreased haugh unit and live weight gain, and had no significant effects on other parameters.

  9. Catalytic conversion of ethanol on H-Y zeolite

    Directory of Open Access Journals (Sweden)

    Čegar Nedeljko

    2005-01-01

    Full Text Available The catalytic activity of the H-form of synthetic zeolite NaY was examined in this study. The catalytic activity was determined according to the rate of ethanol conversion in a gas phase in the static system. In the conversion of ethanol on synthetic NaY zeolite at 585, 595, and 610 K, on which the reaction develops at an optimal rate, ethene and diethyl ether are evolved in approximately the same quantity. After transforming the NaY zeolite into the H-form, its catalytic activity was extremely increases so, the reaction develops at a significantly lower temperature with a very large increase in the reaction rate. The distribution of the products also changes, so that at lower temperatures diethyl ether is elvolved in most cases, and the development of ethene is favored at higher ones, and after a certain period of time there is almost complete conversion of ethanol into ethene. The increase in catalytic activity, as well as the change of selectivity of conversion of ethanol on the H-form of zeolite, is the result of removing Na+ cations in the NaY zeolite, so that more acidic catalyst is obtained which contains a number of acidic catalytically active centers, as well as a more powerful one compared to the original NaY zeolite.

  10. Inhibition of palm oil oxidation by zeolite nanocrystals.

    Science.gov (United States)

    Tan, Kok-Hou; Awala, Hussein; Mukti, Rino R; Wong, Ka-Lun; Rigaud, Baptiste; Ling, Tau Chuan; Aleksandrov, Hristiyan A; Koleva, Iskra Z; Vayssilov, Georgi N; Mintova, Svetlana; Ng, Eng-Poh

    2015-05-13

    The efficiency of zeolite X nanocrystals (FAU-type framework structure) containing different extra-framework cations (Li(+), Na(+), K(+), and Ca(2+)) in slowing the thermal oxidation of palm oil is reported. The oxidation study of palm oil is conducted in the presence of zeolite nanocrystals (0.5 wt %) at 150 °C. Several characterization techniques such as visual analysis, colorimetry, rheometry, total acid number (TAN), FT-IR spectroscopy, (1)H NMR spectroscopy, and Karl Fischer analyses are applied to follow the oxidative evolution of the oil. It was found that zeolite nanocrystals decelerate the oxidation of palm oil through stabilization of hydroperoxides, which are the primary oxidation product, and concurrently via adsorption of the secondary oxidation products (alcohols, aldehydes, ketones, carboxylic acids, and esters). In addition to the experimental results, periodic density functional theory (DFT) calculations are performed to elucidate further the oxidation process of the palm oil in the presence of zeolite nanocrystals. The DFT calculations show that the metal complexes formed with peroxides are more stable than the complexes with alkenes with the same ions. The peroxides captured in the zeolite X nanocrystals consequently decelerate further oxidation toward formation of acids. Unlike the monovalent alkali metal cations in the zeolite X nanocrystals (K(+), Na(+), and Li(+)), Ca(2+) reduced the acidity of the oil by neutralizing the acidic carboxylate compounds to COO(-)(Ca(2+))1/2 species.

  11. Applications of natural zeolites on agriculture and food production.

    Science.gov (United States)

    Eroglu, Nazife; Emekci, Mevlut; Athanassiou, Christos G

    2017-08-01

    Zeolites are crystalline hydrated aluminosilicates with remarkable physical and chemical properties, which include losing and receiving water in a reverse way, adsorbing molecules that act as molecular sieves, and replacing their constituent cations without structural change. The commercial production of natural zeolites has accelerated during the last 50 years. The Structure Commission of the International Zeolite Association recorded more than 200 zeolites, which currently include more than 40 naturally occurring zeolites. Recent findings have supported their role in stored-pest management as inert dust applications, pesticide and fertilizer carriers, soil amendments, animal feed additives, mycotoxin binders and food packaging materials. There are many advantages of inert dust application, including low cost, non-neurotoxic action, low mammalian toxicity and safety for human consumption. The latest consumer trends and government protocols have shifted toward organic origin materials to replace synthetic chemical products. In the present review, we summarize most of the main uses of zeolites in food and agruculture, along with the with specific paradigms that illustrate their important role. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  12. Xylenes transformation over zeolites ZSM-5 ruled by acidic properties

    Science.gov (United States)

    Gołąbek, Kinga; Tarach, Karolina A.; Góra-Marek, Kinga

    2018-03-01

    The studies presented in this work offer an insight into xylene isomerization process, followed by 2D COS analysis, in the terms of different acidity of microporous zeolites ZSM-5. The isomerisation reaction proceeded effectively over zeolites ZSM-5 of Si/Al equal of 12 and 32. Among them, the Al-poorer zeolite (Si/Al = 32) was found to offer the highest conversion and selectivity to p-xylene with the lowest number of disproportionation products, both in ortho- and meta-xylene transformation. Further reduction of Brønsted acidity facilitated the disproportionation path (zeolites of Si/Al = 48 and 750). The formation of intermediate species induced by the diffusion constraints for m-xylene in 10-ring channels was rationalized in the terms of the methylbenzenium ions formation inside the rigid micropore environment. Finally, both microporous character of zeolite and the optimised acidity were found to be crucial for high selectivity to the most desired product i.e. p-xylene. The analysis of asynchronous maps allowed for concluding on the order of the appearance of the respective products on the zeolite surface.

  13. Influence of zeolitized perlite on blended cement properties

    Directory of Open Access Journals (Sweden)

    Vaičiukynienė Danutė

    2016-01-01

    Full Text Available Perlite is the mineral of volcanic origin. Expanded perlite has good heat insulation and sound absorption properties. It is light, resistant to fire, moisture and micro-organisms, harmless to health. However, due to the presence of hyaline phase, its use in Portland cement mixture is problematic. In this paper, the zeolitization of expanded perlite was carried out to improve its hydraulic properties. The conversion of expanded perlite into zeolite material was carried out when Na2O : Al2O3 : SiO2 : H2O molar ratio was equal to 2: 1: 2: 10 and the suspension of starting materials was treated for 3 hours at 100°C temperature. Mechanical and physical properties of hardened cement paste containing 0%, 5%, 10%, and 15% of pure perlite admixtures, zeolitized perlite, and perlite altered to calcium (Ca2+ zeolite were researched. The results showed that zeolitization of expanded perlite activates its hydraulic properties; after 28 days of hydration under normal conditions, the compressive strength of the specimens modified with 5% of zeolitized perlite admixture was 49-50 MPa, whereas the compressive strength of the specimens containing 5% of pure perlite admixture was only 33 MPa.

  14. Synthesis of uniform-sized zeolite from windshield waste

    International Nuclear Information System (INIS)

    Kim, Jae-Chan; Choi, Mingu; Song, Hee Jo; Park, Jung Eun; Yoon, Jin-Ho; Park, Kyung-Soo; Lee, Chan Gi; Kim, Dong-Wan

    2015-01-01

    We demonstrate the synthesis of A-type zeolite from mechanically milled windshield waste via acid treatment and a low-temperature hydrothermal method. As-received windshield cullet was crushed to a fine powder and impurities were removed by HNO 3 treatment. The resulting glass powder was used as the source material for the hydrothermal synthesis of A-type zeolite. Crystal structure, morphology, and elemental composition changes of the windshield waste were evaluated at each step of the process through scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectrometry, etc. After a high-energy milling process, the glass had an average particle size of 520 nm; after acid treatment, its composition was over 94% silica. Zeolite was successfully synthesized in the A-type phase with a uniform cubic shape. - Highlights: • Environmental-friendly recycling of windshield waste for high valuable product of zeolite. • Synthesis of zeolite form windshield waste via a low-temperature hydrothermal process. • High-energy milling effect on the uniform cubic shape and high-purity A-type zeolite.

  15. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  16. Polypropylene obtained through zeolite supported catalysts

    Directory of Open Access Journals (Sweden)

    Queli C. Bastos

    2004-01-01

    Full Text Available Propylene polymerizations were carried out with f2C(Flu(CpZrCl2 and SiMe2(Ind2ZrCl2 catalysts supported on silica, zeolite sodic mordenite (NaM and acid mordenite (HM. The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]. The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f2C(Flu(CpZrCl2, SiO2 and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereoregularity.

  17. Exchange of Co(II) Ions in H-BEA Zeolites. Identification of Aluminium Pairs in the Zeolite Framework

    Czech Academy of Sciences Publication Activity Database

    Bortnovsky, Oleg; Sobalík, Zdeněk; Wichterlová, Blanka

    2001-01-01

    Roč. 46, č. 2 (2001), s. 265-275 ISSN 1387-1811 R&D Projects: GA AV ČR IBS4040015; GA MŠk OC D15.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : BEA zeolites * cobalt ion exchange * zeolite framework aluminium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.497, year: 2001

  18. Pyrolysis of scrap tyres with zeolite USY

    International Nuclear Information System (INIS)

    Shen Boxiong; Wu Chunfei; Wang Rui; Guo Binbin; Liang Cai

    2006-01-01

    A zeolite catalyst of ultrastable Y-type (USY) was investigated in the research of two staged pyrolysis-catalysis of scrap tyres. Scrap tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary catalytic reactor. The main objective of this paper was to investigate the effect of zeolite USY on the yield of products and the composition of derived oil. The influences of several parameters such as pyrolysis temperature, catalytic temperature, catalyst/tyre ratio, heating rate, etc. on the yield of the derived oil, char and gas were investigated. It showed that the increase of catalytic temperature and catalyst/tyre ratio resulted in high yield of gas at the expense of the oil yield. For example, when the catalyst/tyre ratio increased from 0.25 to 1.0, the yield of gas increased from 30.5 to 49.9 wt.%, and the oil yield decreased nearly two-fold from 31.6 to 12.7 wt.%. The concentration of light naphtha (boiling point < 160 deg. C) was also investigated in this study. And the high catalyst/tyre ratio favored to increase the concentration of light naphtha (<160 deg. C) in oil. In order to study the composition of derived oil, a distilled fraction (<280 deg. C), which was 92.5 wt.% of the oil obtained from catalytic pyrolysis of scrap tyre at a pyrolysis temperature, catalytic temperature and catalyst/tyre ratio of 500, 400 deg. C and 0.5, respectively, was analyzed with gas chromatography/mass spectrometry (GC/MS). The distillate was found to contain 1.23 wt.% benzene, 9.35 wt.% toluene, 3.68 wt.% ethylbenzene, 12.64 wt.% xylenes, 1.81 wt.% limonene and 13.89 wt.% PAHs, etc., where the single ring aromatics represented a significant potential use as chemicals

  19. Pyrolysis of scrap tyres with zeolite USY.

    Science.gov (United States)

    Shen, Boxiong; Wu, Chunfei; Wang, Rui; Guo, Binbin; Liang, Cai

    2006-09-21

    A zeolite catalyst of ultrastable Y-type (USY) was investigated in the research of two staged pyrolysis-catalysis of scrap tyres. Scrap tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary catalytic reactor. The main objective of this paper was to investigate the effect of zeolite USY on the yield of products and the composition of derived oil. The influences of several parameters such as pyrolysis temperature, catalytic temperature, catalyst/tyre ratio, heating rate, etc. on the yield of the derived oil, char and gas were investigated. It showed that the increase of catalytic temperature and catalyst/tyre ratio resulted in high yield of gas at the expense of the oil yield. For example, when the catalyst/tyre ratio increased from 0.25 to 1.0, the yield of gas increased from 30.5 to 49.9 wt.%, and the oil yield decreased nearly two-fold from 31.6 to 12.7 wt.%. The concentration of light naphtha (boiling point tyre ratio favored to increase the concentration of light naphtha (composition of derived oil, a distilled fraction (tyre at a pyrolysis temperature, catalytic temperature and catalyst/tyre ratio of 500, 400 degrees C and 0.5, respectively, was analyzed with gas chromatography/mass spectrometry (GC/MS). The distillate was found to contain 1.23 wt.% benzene, 9.35 wt.% toluene, 3.68 wt.% ethylbenzene, 12.64 wt.% xylenes, 1.81 wt.% limonene and 13.89 wt.% PAHs, etc., where the single ring aromatics represented a significant potential use as chemicals.

  20. PENJERAPAN P-KHLOROFENOL DALAM AIR LIMBAH DENGAN ZEOLIT (Adsorption of p-Chlorophenol from Wastewater using Zeolite

    Directory of Open Access Journals (Sweden)

    Sarto Sarto

    2007-07-01

    Full Text Available ABSTRAK Penelitian ini bertujuan untuk mempelajari kemampuan zeolit untuk menjerap p-khlorofenol dari limbah cair secara batch, pada suhu 30 °C dan tekanan 1 atmosfer. Hasil penelitian menunjukkan bahwa proses penjerapan mengikuti persamaan Freundlich dan bersifat reversibel sebagian. Nisbah kinerja desorbsi dan penjerapan adalah antara 31,85 % dan 49,36 %. Kemampuan zeolit untuk menjerap p-khlorofenol meningkat dengan semakin rendahnya pH. pada nilai pH 3,92, berat zeolit 30 g, dan konsentrasi awal p-khlorofenol 97,302 mg/L. Adapun jumlah p-khlorofenol yang terjerap adalah sebesar 8,319 mg/L.   ABSTRACT The aim of this research is to study the characteristics of zeolit to adsorb p-chlorophenol from wastewater in a batch reactor at 30 oC and atmospheric conditions. The experimental results show that the adsorbtion process is partially reversible and fits with Freundlich Equation. The ratio of  desorption and adsortion performance is between 31.85 % and 49.36 %.  The performance of zeolit to adsorb p-chlorophenol increases with decreasing pH. At  pH about 3.92, using 30 g zeolit and 97.302 mg  p-chlorophenol/L. The concentration of adsorbed p-chlorophenol is about 8.319 mg/L.

  1. Sympletic quantization of constrained systems

    Energy Technology Data Exchange (ETDEWEB)

    Barcelos-Neto, J.; Wotzasek, C. (Inst. de Fisica, Univ. Federal do Rio de Janeiro, Caixa Postal 68528, 21945 Rio de Janeiro (BR))

    1992-06-21

    In this paper it is shown that the symplectic two-form, which defines the geometrical structure of a constrained theory in the Faddeev-Jackiw approach, may be brought into a non-degenerated form, by an iterative implementation of the existing constraints. The resulting generalized brackets coincide with those obtained by the Dirac bracket approach, if the constrained system under investigation presents only second-class constraints. For gauge theories, a symmetry breaking term must be supplemented to bring the symplectic form into a non-singular configuration. At present, the singular symplectic two-form provides directly the generators of the time independent gauge transformations.

  2. Constraining the evolution of the Hubble Parameter using cosmic chronometers

    Science.gov (United States)

    Dickinson, Hugh

    2017-08-01

    Substantial investment is being made in space- and ground-based missions with the goal of revealing the nature of the observed cosmic acceleration. This is one of the most important unsolved problems in cosmology today.We propose here to constrain the evolution of the Hubble parameter [H(z)] between 1.3 fundamental nature of dark energy.

  3. A discretized algorithm for the solution of a constrained, continuous ...

    African Journals Online (AJOL)

    A discretized algorithm for the solution of a constrained, continuous quadratic control problem. ... Numerical solution techniques such as Function space algorithm (FSA), Extended conjugate gradient method (ECGM) and Imbedding extended conjugate gradient method (MECGM) are common techniques for solving optimal ...

  4. Effect of Gravity Level on the Particle Shape and Size During Zeolite Crystal Growth

    Science.gov (United States)

    Song, Hong-Wei; Ilebusi, Olusegun J.; Sacco, Albert, Jr.

    2003-01-01

    A microscopic diffusion model is developed to represent solute transport in the boundary layer of a growing zeolite crystal. This model is used to describe the effect of gravity on particle shape and solute distribution. Particle dynamics and crystal growth kinetics serve as the boundary conditions of flow and convection-diffusion equations. A statistical rate theory is used to obtain the rate of solute transport across the growing interface, which is expressed in terms of concentration and velocity of solute species. Microgravity can significantly decrease the solute velocity across the growing interface compared to its earth-based counterpart. The extent of this reduction highly depends on solute diffusion constant in solution. Under gravity, the flow towards the crystal enhances solute transport rate across the growing interface while the flow away from crystals reduces this rate, suggesting a non-uniform growth rate and thus an elliptic final shape. However, microgravity can significantly reduce the influence of flow and obtain a final product with perfect spherical shape. The model predictions compare favorably with the data of space experiment of zeolites grown in space.

  5. Hybrid Zeolitic Imidazolate Frameworks: Controlling Framework Porosity and Functionality by Mixed-Linker Synthesis

    KAUST Repository

    Thompson, Joshua A.

    2012-05-22

    Zeolitic imidazolate frameworks (ZIFs) are a subclass of nanoporous metal-organic frameworks (MOFs) that exhibit zeolite-like structural topologies and have interesting molecular recognition properties, such as molecular sieving and gate-opening effects associated with their pore apertures. The synthesis and characterization of hybrid ZIFs with mixed linkers in the framework are described in this work, producing materials with properties distinctly different from the parent frameworks (ZIF-8, ZIF-90, and ZIF-7). NMR spectroscopy is used to assess the relative amounts of the different linkers included in the frameworks, whereas nitrogen physisorption shows the evolution of the effective pore size distribution in materials resulting from the framework hybridization. X-ray diffraction shows these hybrid materials to be crystalline. In the case of ZIF-8-90 hybrids, the cubic space group of the parent frameworks is continuously maintained, whereas in the case of the ZIF-7-8 hybrids there is a transition from a cubic to a rhombohedral space group. Nitrogen physisorption data reveal that the hybrid materials exhibit substantial changes in gate-opening phenomena, either occurring at continuously tunable partial pressures of nitrogen (ZIF-8-90 hybrids) or loss of gate-opening effects to yield more rigid frameworks (ZIF-7-8 hybrids). With this synthetic approach, significant alterations in MOF properties may be realized to suit a desired separation or catalytic process. © 2012 American Chemical Society.

  6. The Effect of Zeolite on Aggregate Stability Indices

    Directory of Open Access Journals (Sweden)

    F. Sohrab

    2016-02-01

    Full Text Available Introduction: Soil structural stability affects the profitability and sustainability of agricultural systems. Particle size distribution (PSD and aggregate stability are the important characteristics of soil. Aggregate stability has a significant impact on the development of the root system, water and carbon cycle and soil resistance against soil erosion. Soil aggregate stability, defined as the ability of the aggregates to remain intact when subject to a given stress, is an important soil property that affects the movement and storage of water, aeration, erosion, biological activity and growth of crops. Dry soil aggregate stability (Mean Weight Diameter (MWD, Geometric Mean Diameter (GMD and Wet Aggregate Stability (WAS are important indices for evaluating soil aggregate stability.To improve soil physical properties, including modifying aggregate, using various additives (organic, inorganic and chemicals, zeolites are among what has been studied.According to traditional definition, zeolites are hydratealuminosilicates of alkaline and alkaline-earth minerals. Their structure is made up of a framework of[SiO4]−4 and [AlO4]−5 tetrahedron linked to each other's cornersby sharing oxygen atoms. The substitution of Si+4 by Al+3 intetrahedral sites results inmore negative charges and a high cation exchange capacity.Zeolites, as natural cation exchangers, are suitable substitutes to remove toxic cations. Among the natural zeolites,Clinoptilolite seems to be the most efficient ion exchanger and ion-selective material forremoving and stabilizing heavy metals.Due to theexisting insufficient technical information on the effects of using different levels of zeolite on physical properties of different types of soils in Iran, the aim of this research was to assess the effects of two different types of zeolite (Clinoptilolite natural zeolite, Z4, and Synthetic zeolite, A4 on aggregate stability indicesof soil. Materials and Methods: In this study at first

  7. Utilization of zeolites synthesized from coal fly ash for the purification of acid mine waters

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, N.; Querol, X.; Ayora, C.; Pereira, C.F.; Janssen-Jurkovicova, M. [CSIC, Barcelona (Spain). Inst. of Earth Sciences ' Jaume Almera'

    2001-09-01

    Two pilot plant products containing 65 and 45% NaP1 zeolite were obtained from two Spanish coal fly ashes (Narcea and Teruel Power Station, respectively). The zeolitic product obtained showed a cation exchange capacity (CEC) of 2.7 and 2.0 mequiv/g, respectively. Decontamination tests of three acid mine waters from southwestern Spain were carried out using the zeolite derived from fly ash and commercial synthetic zeolite. The results demonstrate that the zeolitic material could be employed for heavy metal uptake in the water purification process. Doses of 5-30 g of zeolite/L have been applied according on the zeolite species and the heavy metal levels. Moreover, the application of zeolites increases the pH. This causes metal-bearing solid phases to precipitate and enhances the efficiency of the decontamination process. 31 refs., 4 figs., 5 tabs.

  8. Synthesis and characterization of zeolite material from coal ashes modified by surfactant

    International Nuclear Information System (INIS)

    Fungaro, D.A.; Borrely, S.I.

    2010-01-01

    Coal ash was used as starting material for zeolite synthesis by means of hydrothermal treatment. The surfactant-modified zeolite (SMZ) was prepared by adsorbing the cationic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) on the external surface of the zeolite from coal ash. The zeolite structure stability was monitored during the characterization of the materials by FTIR, XDR and SEM. The structural parameters of surfactant-modified zeolite are very close to that of corresponding non-modified zeolite which indicates that the crystalline nature of the zeolite remained intact after required chemical treatment with HDTMA-Br molecules and heating treatment for drying. The most intense peaks in the FTIR spectrum of HDTMA-Br were observed in SMZ spectrum confirming adsorption of surfactant on zeolites. (author)

  9. How Our Biology Constrains Our Science

    Directory of Open Access Journals (Sweden)

    Vlerick Michael

    2017-04-01

    Full Text Available Reasoning from a naturalistic perspective, viewing the mind as an evolved biological organ with a particular structure and function, a number of influential philosophers and cognitive scientists claim that science is constrained by human nature. How exactly our genetic constitution constrains scientific representations of the world remains unclear. This is problematic for two reasons. Firstly, it often leads to the unwarranted conclusion that we are cognitively closed to certain aspects or properties of the world. Secondly, it stands in the way of a nuanced account of the relationship between our cognitive and perceptual wiring and scientific theory. In response, I propose a typology or classification of the different kinds of biological constraints and their sources on science. Using Boden’s (1990 notion of a conceptual space, I distinguish between constraints relating to the ease with which we can reach representations within our conceptual space (which I call ‘biases’ and constraints causing possible representations to fall outside of our conceptual space. This last kind of constraints does not entail that some aspects or properties of the world cannot be represented by us – as argued by advocates of ‘cognitive closure’ – merely that some ways of representing the world are inaccessible to us. It relates to what Clark (1986 and Rescher (1990 have framed as ‘the alien scientist hypothesis’ (the possibility that alien scientists, endowed with radically different cognitive abilities, could produce representations of the world that are unintelligible to us. The purpose of this typology is to provide some much needed clarity and structure to the debate about biological constraints on science.

  10. Antifungal activities against toxigenic Fusarium specie and deoxynivalenol adsorption capacity of ion-exchanged zeolites.

    Science.gov (United States)

    Savi, Geovana D; Cardoso, William A; Furtado, Bianca G; Bortolotto, Tiago; Zanoni, Elton T; Scussel, Rahisa; Rezende, Lucas F; Machado-de-Ávila, Ricardo A; Montedo, Oscar R K; Angioletto, Elidio

    2018-03-04

    Zeolites are often used as adsorbents materials and their loaded cations can be exchanged with metal ions in order to add antimicrobial properties. The aim of this study was to use the 4A zeolite and its derived ion-exchanged forms with Zn 2+ , Li + , Cu 2+ and Co 2+ in order to evaluate their antifungal properties against Fusarium graminearum, including their capacity in terms of metal ions release, conidia germination and the deoxynivalenol (DON) adsorption. The zeolites ion-exchanged with Li + , Cu 2+ , and Co 2+ showed an excellent antifungal activity against F. graminearum, using an agar diffusion method, with a zone of inhibition observed around the samples of 45.3 ± 0.6 mm, 25.7 ± 1.5 mm, and 24.7 ± 0.6 mm, respectively. Similar results using agar dilution method were found showing significant growth inhibition of F. graminearum for ion-exchanged zeolites with Zn 2+ , Li + , Cu 2+ , and Co 2+ . The fungi growth inhibition decreased as zeolite-Cu 2+ >zeolite-Li + >zeolite-Co 2+ >zeolite-Zn 2+ . In addition, the conidia germination was strongly affected by ion-exchanged zeolites. With regard to adsorption capacity, results indicate that only zeolite-Li + were capable of DON adsorption significantly (P concentration. The antifungal effects of the ion-exchanged zeolites can be ascribed to the interactions of the metal ions released from the zeolite structure, especially for zeolite-Li + , which showed to be a promising agent against F. graminearum and its toxin.

  11. Molecular interactions of alcohols with zeolite BEA and MOR frameworks.

    Science.gov (United States)

    Stückenschneider, Kai; Merz, Juliane; Schembecker, Gerhard

    2013-12-01

    Zeolites can adsorb small organic molecules such as alcohols from a fermentation broth. Also in the zeolite-catalyzed conversion of alcohols to biofuels, biochemicals, or gasoline, adsorption is the first step. Several studies have investigated the adsorption of alcohols in different zeolites experimentally, but computational investigations in this field have mostly been restricted to zeolite MFI. In this study, the adsorption of C1-C4 alcohols in BEA and MOR was investigated using density functional theory (DFT). Calculated adsorption geometries and the corresponding energies of the designed cluster models were comparable to periodic calculations, and the adsorption energies were in the same range as the corresponding computational and experimental values reported in the literature for zeolite MFI. Thus, BEA and MOR may be good adsorption materials for alcohols in the field of downstream processing and catalysis. Aside from the DFT calculations, adsorption isotherms were determined experimentally in this study from aqueous solutions. For BEA, the adsorption of significant amounts of alcohol from aqueous solution was observed experimentally. In contrast, MOR was loaded with only a very small amount of alcohol. Although differences were found between the affinities obtained from gas-phase DFT calculations and those observed experimentally in aqueous solution, the computational data presented here represent molecular level information on the geometries and energies of C1-C4 alcohols adsorbed in zeolites BEA and MOR. This knowledge should prove very useful in the design of zeolite materials intended for use in adsorption and catalytic processes, as it allows adsorption behavior to be predicted via judiciously designed computational models.

  12. Tritium and deuterium NMR studies of zeolite catalyzed isotope exchange reactions

    International Nuclear Information System (INIS)

    Garnett, J.L.; Long, M.A.; Williams, P.G.

    1986-01-01

    The use of 3 H and 2 H nmr spectroscopy in studies of hydrogen isotope exchange over zeolites and metal loaded zeolites is important for both development of new catalytic methods of producing labelled compounds and for investigation of the mechanisms of catalysis over zeolites, as selected examples illustrate. 9 refs.; 1 figure; 2 tabs

  13. Effect of rare earth cations on activity of type Y zeolites in ethylene transformations

    International Nuclear Information System (INIS)

    Amezhnova, G.N.; Zhavoronkov, M.N.; Dorogochinskij, A.Z.; Proskurin, A.L.; Shmailova, V.I.

    1984-01-01

    The ethylene transformations on type Y rare earth zeolites with high degrees of sodium exchange are studied. It is shown that rare earth cations increase zeolites activity with growth of electronoacceptor capacity. The ethylene oligomerization occurs on polyvalent cations while subsequent oligomer transformations - on hydroxyl groups of zeolites

  14. Fabrication of zeolite/polymer multilayer composite membranes for carbon dioxide capture: Deposition of zeolite particles on polymer supports.

    Science.gov (United States)

    Ramasubramanian, Kartik; Severance, Michael A; Dutta, Prabir K; Ho, W S Winston

    2015-08-15

    Membranes, due to their smaller footprint and potentially lower energy consumption than the amine process, offer a promising route for post-combustion CO2 capture. Zeolite Y based inorganic selective layers offer a favorable combination of CO2 permeance and CO2/N2 selectivity, membrane properties crucial to the economics. For economic viability on large scale, we propose to use flexible and scalable polymer supports for inorganic selective layers. The work described in this paper developed a detailed protocol for depositing thin zeolite Y seed layers on polymer supports, the first step in the synthesis of a polycrystalline zeolite Y membrane. We also studied the effects of support surface morphology (pore size and surface porosity) on the quality of deposition and identified favorable supports for the deposition. Two different zeolite Y particles with nominal sizes of 200 nm and 40 nm were investigated. To obtain a complete coverage of zeolite particles on the support surface with minimum defects and in a reproducible manner, a vacuum-assisted dip-coating technique was developed. Images obtained using both digital camera and optical microscope showed the presence of color patterns on the deposited surface which suggested that the coverage was complete. Electron microscopy revealed that the particle packing was dense with some drying cracks. Layer thickness with the larger zeolite Y particles was close to 1 μm while that with the smaller particles was reduced to less than 0.5 μm. In order to reduce drying cracks for layers with smaller zeolite Y particles, thickness was reduced by lowering the dispersion concentration. Transport measurement was used as an additional technique to characterize these layers. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Characterization of Mexican zeolite minerals; Caracterizacion de minerales zeoliticos mexicanos

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez C, M.J

    2005-07-01

    50% of the Mexican territory is formed by volcanic sequences of the Pliocene type, which appear extensively in the northwest states (Sonora, Sinaloa, Chihuahua, Durango) and west of Mexico (Jalisco and Nayarit), in central Mexico (Zacatecas, Guanajuato, San Luis Potosi, Queretaro, Hidalgo) and south of Mexico (Guerrero, Oaxaca); therefore, it is to be expected that in our country big locations of natural zeolites exist in its majority of the clinoptilolite type. The present study was focused toward the characterization of two Mexican natural zeolite rocks presumably of the clinoptilolite and filipsite types, one of them comes from the state of Chihuahua and the other of a trader company of non metallic minerals, due that these materials are not characterized, its are not known their properties completely and therefore, the uses that can be given to these materials. In this investigation work it was carried out the characterization of two Mexican zeolite rocks, one coming from the Arroyo zone, municipality of La Haciendita, in the state of Chihuahua; and the other one was bought to a trader company of non metallic minerals. The two zeolites so much in their natural form as conditioned with sodium; they were characterized by means of X-ray diffraction, scanning electron microscopy of high vacuum and elementary microanalysis (EDS), surface area analysis (BET), thermal gravimetric analysis. To differentiate the heulandite crystalline phase of the other clinoptilolite rock, its were carried out thermal treatments. The quantification of Al, Na, Ca, K, Mg, Fe was carried out in solution, by means of atomic absorption spectroscopy and the quantity of Si was determined by gravimetry. The zeolite rocks presented for the major part the crystalline heulandite and clinoptilolite phases for the most part, and it was found that the zeolite coming from the state of Chihuahua possesses a bigger content of heulandite and the denominated filipsite it is really a zeolite

  16. Preparation and Characterization of Zeolite Membrane for Bioethanol Purification

    Directory of Open Access Journals (Sweden)

    Aprilina Purbasari

    2013-06-01

    Full Text Available The use of bioethanol as an alternative fuel with a purity of more than 99.5% wt has prompted research on bioethanol purification. One of the promising methods used for bioethanol purification is pervaporation membrane. This research is aimed to prepare and characterize zeolite membranes for pervaporation membrane. The membrane preparation consisted of two stages, namely support preparation and zeolite deposition on the support. In support preparation, α- alumina and kaolin with specific composition (50:30; 40:40; 50:30 was mixed with additives and water. After pugging and aging process, the mixture became paste and extruded into tubular shape. The tube was then calcined at temperature of 1250 °C for 3 hours. After that, zeolite 4A was deposited on the tubes using clear solution made of 10 %wt zeolite and 90 %wt water and heated at temperature of 80 °C for 3 hours. Furthermore, the resulting zeolite membranes was washed with deionized water for 5 minutes and dried in oven at temperature of 100 °C for 24 hours. Characterization of zeolite membranes included mechanical strength test, XRD, and SEM. In the mechanical strength test, the membrane sample with α- alumina:kaolin = 50:30 (membrane A has the highest mechanical strength of 46.65 N/mm2. Result of XRD analysis for the membrane A indicated that mullite and corundum phases were formed, which mullite phase was more dominant. Meanwhile the result of SEM analysis shows that zeolite crystals have been formed and covered the pores support, but the deposition of zeolite has not been optimal yet. The performance examination for bioethanol purification showed that the membrane could increase the purity of bioethanol from 95% to 98.5% wt. © 2013 BCREC UNDIP. All rights reservedReceived: 23rd October 2012; Revised: 15th February 2013; Accepted: 16th February 2013[How to Cite: Purbasari, A., Istirokhatun, T., Devi, A.M., Mahsunnah, L. , Susanto, H. (2013. Preparation and Characterization of Zeolite

  17. Modification of Polyamide Knitted Fabric using Different Zeolites

    Directory of Open Access Journals (Sweden)

    Ojsteršek Alenka

    2017-05-01

    Full Text Available The aim of this research was to apply three different types of zeolites and the combination thereof in the form of a very fine powder, together with different chemicals and additives on polyamide knitted fabric according to an industrially acceptable exhaustion procedure in order to study changes in the morphology, optical properties and wettability of surfaces. Zeolites were analysed using Scanning Electron Microscopy (SEM, Fourier Transform Infrared Spectroscopy (FTIR and gas physiosorption. Additionally, the morphology of zeolite-coated surfaces was examined closely using SEM, while changes in molecular-chemical level were examined by means of IR spectroscopy. Optical properties were studied using CIE colour measurement and diffuse refl ectance profile determination, while the hydrophilic/hydrophobic character was examined using goniometry. The obtained results show the suitability of the employed exhaustion procedure, depending on the type of zeolite and the composition of the treatment bath. The results also provided evidence of the enhanced wettability of PA fabrics using 4A and 13X zeolites in combination with selected additives.

  18. Synthesis of type A zeolite from calcinated kaolin

    International Nuclear Information System (INIS)

    Rodrigues, E.C.; Neves, R.F.; Souza, J.A.S.; Moraes, C.G.; Macedo, E.N.

    2011-01-01

    The mineral production has caused great concern in environmental and industrial scenario due to the effects caused to the environment. The industries of processing kaolin for paper are important economically for the state of Para, but produce huge quantities of tailings, which depend on large areas to be stocked. This material is rich in silico-aluminates can be recycled and used as raw material for other industries. The objective is to synthesize zeolite A at different temperatures of calcination and synthesis. The starting materials and synthesis of zeolite A have been identified and characterized through analysis of X-ray diffraction (DRX) and scanning electron microscopy (MEV). The synthesis process of zeolite A, using as source of silica and the aluminum metakaolin, which was calcined at temperatures of 700 ° C and 800 ° C for 2 hours of landing in a burning furnace type muffle. Observed in relation to the calcination of kaolin as the main phase, the metakaolin. This is just a removal of water from its structure, so we opted for the lower temperature, less energy consumption. The synthesis process of zeolite A, produced good results for the formation of zeolites type A, which were characterized with high purities. (author)

  19. Copper removal using bio-inspired polydopamine coated natural zeolites.

    Science.gov (United States)

    Yu, Yang; Shapter, Joseph G; Popelka-Filcoff, Rachel; Bennett, John W; Ellis, Amanda V

    2014-05-30

    Herein, for the first time, natural clinoptilolite-rich zeolite powders modified with a bio-inspired adhesive, polydopamine (PDA), have been systematically studied as an adsorbent for copper cations (Cu(II)) from aqueous solution. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) revealed successful grafting of PDA onto the zeolite surface. The effects of pH (2-5.5), PDA treatment time (3-24h), contact time (0 to 24h) and initial Cu(II) ion concentrations (1 to 500mgdm(-3)) on the adsorption of Cu(II) ions were studied using atomic absorption spectroscopy (AAS) and neutron activation analysis (NAA). The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. The maximum adsorption capacities of Cu(II) were shown to be 14.93mgg(-1) for pristine natural zeolite and 28.58mgg(-1) for PDA treated zeolite powders. This impressive 91.4% increase in Cu(II) ion adsorption capacity is attributed to the chelating ability of the PDA on the zeolite surface. Furthermore studies of recyclability using NAA showed that over 50% of the adsorbed copper could be removed in mild concentrations (0.01M or 0.1M) of either acid or base. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Methanation of CO2 over Zeolite-Encapsulated Nickel Nanoparticles

    DEFF Research Database (Denmark)

    Goodarzi, Farnoosh; Kang, Liqun; Wang, Feng Ryan

    2018-01-01

    Efficient methanation of CO2 relies on the development of more selective and stable heterogeneous catalysts. Here we present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite-1. In this method, the zeolite is modified by selective desilication, which creates intr...... Ni h-1. The encapsulated Ni nanoparticles show no change in activity or selectivity after 50 h of operation, although post-catalysis characteri-sation reveals some particle migration.......Efficient methanation of CO2 relies on the development of more selective and stable heterogeneous catalysts. Here we present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite-1. In this method, the zeolite is modified by selective desilication, which creates intra......-particle voids and mesopores that facilitate the formation of small and well-dispersed nanoparticles upon impregnation and reduction. TEM and XPS analysis confirm that a significant part of the Ni nanoparticles are situated inside the zeolite rather than on the outer surface. The encapsulation results...

  1. Bendable Zeolite Membranes: Synthesis and Improved Gas Separation Performance.

    Science.gov (United States)

    Wang, Bo; Ho, W S Winston; Figueroa, Jose D; Dutta, Prabir K

    2015-06-23

    Separation and sequestration of CO2 emitted from fossil energy fueled electric generating units and industrial facilities will help in reducing anthropogenic CO2, thereby mitigating its adverse climate change effects. Membrane-based gas separation has the potential to meet the technical challenges of CO2 separation if high selectivity and permeance with low costs for large-scale manufacture are realized. Inorganic zeolite membranes in principle can have selectivity and permeance considerably higher than polymers. This paper presents a strategy for zeolite growth within the pores of a polymer support, with crystallization time of an hour. With a thin coating of 200-300 nm polydimethylsiloxane (PDMS) on the zeolite-polymer composite, transport data for CO2/N2 separation indicate separation factors of 35-45, with CO2 permeance between 1600 and 2200 GPU (1 GPU = 3.35 × 10(-10) mol/(m(2) s Pa)) using dry synthetic mixtures of CO2 and N2 at 25 °C. The synthesis process results in membranes that are highly reproducible toward transport measurements and exhibit long-term stability (3 days). Most importantly, these membranes because of the zeolite growth within the polymer support, as contrasted to conventional zeolite growth on top of a support, are mechanically flexible.

  2. Phenol removal from wastewater by adsorption on zeolitic composite.

    Science.gov (United States)

    Bizerea Spiridon, Otilia; Preda, Elena; Botez, Alexandru; Pitulice, Laura

    2013-09-01

    It is well known that adsorption is an efficient method of removal of various pollutants from wastewater. The present study examines the phenol removal from water by adsorption on a new material, based on zeolitic volcanic tuff. This compound contains zeolitic tuff and cellulose, another known adsorbent, in a mass ratio of 4 to 1. The performances of the new adsorbent composite were compared with those of a widely used adsorbent material, zeolitic volcanic tuff. The adsorbent properties were tested on batch synthetic solutions containing 1-10 mg L(-1) (1-10 ppm) phenol, at room temperature without pH adjustment. The influence of the adsorbent dose, pH and contact time on the removal degree of phenol from water was investigated. The experimental data were modeled using the Langmuir, Freundlich, and Temkin adsorption isotherms. The Langmuir model was found to best represent our data revealing a monolayer adsorption with a maximum adsorption capacity between 0.12 and 0.53 mg g(-1) at 25 °C, for 2.00 g of adsorbent, depending on the initial phenol concentration. The adsorption kinetic study was performed using a pseudo-first- and pseudo-second-order kinetic models illustrating that phenol adsorption on zeolite composite is well described by pseudo-first kinetic equations. Our results indicated that phenol adsorption on the new adsorbent composite is superior to that on the classic zeolite.

  3. Synthesis of high ion exchange zeolites from coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Querol, X.; Moreno, N.; Alastuey, A.; Juan, R.; Andres, J.M.; Lopez-Soler, A.; Ayora, C.; Medinaceli, A.; Valero, A. [CSIC, Barcelona (Spain)

    2007-07-01

    This study focuses on the synthesis at a pilot plant scale of zeolitic material obtained from the coal fly ashes of the Teruel and Narcea power plants in Spain. After the optimisation of the synthesis parameters at laboratory scale, the Teruel and Narcea fly ashes were selected as low and high glass fly ashes. The pilot plant scale experiments were carried out in a 10 m{sup 3} reactor of Clariant SA (Barcelona, Spain). The results allowed obtaining 1.1 and 2.2 tonnes of zeolitic material with 40 and 55% of NaP1 content, in two single batch experiments of 24 and 8 hours, for Teruel and Narcea fly ashes, respectively. The cation exchange capacities (CEC) of the final product reached 2.0 and 2.7 meq g{sup -1} for Teruel and Narcea zeolitic material, respectively, which are very close to the usual values reached by the high quality natural zeolitic products. Finally, with the aim of testing possible applications of the commercial NaP1-IQE and pilot plant NaP1-Narcea zeolitic products in water decontamination, efficiency for metal uptake from waste waters from electroplating baths was investigated.

  4. Enhanced water transport and salt rejection through hydrophobic zeolite pores

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O’Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N.

    2017-12-01

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  5. Intensified Biobutanol Recovery by using Zeolites with Complementary Selectivity.

    Science.gov (United States)

    Van der Perre, Stijn; Gelin, Pierre; Claessens, Benjamin; Martin-Calvo, Ana; Cousin Saint Remi, Julien; Duerinck, Tim; Baron, Gino V; Palomino, Miguel; Sánchez, Ledys Y; Valencia, Susana; Shang, Jin; Singh, Ranjeet; Webley, Paul A; Rey, Fernando; Denayer, Joeri F M

    2017-07-21

    A vapor-phase adsorptive recovery process is proposed as an alternative way to isolate biobutanol from acetone-butanol-ethanol (ABE) fermentation media, offering several advantages compared to liquid phase separation. The effect of water, which is still present in large quantities in the vapor phase, on the adsorption of the organics could be minimized by using hydrophobic zeolites. Shape-selective all-silica zeolites CHA and LTA were prepared and evaluated with single-component isotherms and breakthrough experiments. These zeolites show opposite selectivities; adsorption of ethanol is favorable on all-silica CHA, whereas the LTA topology has a clear preference for butanol. The molecular sieving properties of both zeolites allow easy elimination of acetone from the mixture. The molecular interaction mechanisms are studied by density functional theory (DFT) simulations. The effects of mixture composition, humidity and total pressure of the vapor stream on the selectivity and separation behavior are investigated. Desorption profiles are studied to maximize butanol purity and recovery. The combination of LTA with CHA-type zeolites (Si-CHA or SAPO-34) in sequential adsorption columns with alternating adsorption and desorption steps allows butanol to be recovered in unpreceded purity and yield. A butanol purity of 99.7 mol % could be obtained at nearly complete butanol recovery, demonstrating the effectiveness of this technique for biobutanol separation processes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Catalytic activities of zeolite compounds for decomposing aqueous ozone.

    Science.gov (United States)

    Kusuda, Ai; Kitayama, Mikito; Ohta, Yoshio

    2013-12-01

    The advanced oxidation process (AOP), chemical oxidation using aqueous ozone in the presence of appropriate catalysts to generate highly reactive oxygen species, offers an attractive option for removing poorly biodegradable pollutants. Using the commercial zeolite powders with various Si/Al ratios and crystal structures, their catalytic activities for decomposing aqueous ozone were evaluated by continuously flowing ozone to water containing the zeolite powders. The hydrophilic zeolites (low Si/Al ratio) with alkali cations in the crystal structures were found to possess high catalytic activity for decomposing aqueous ozone. The hydrophobic zeolite compounds (high Si/Al ratio) were found to absorb ozone very well, but to have no catalytic activity for decomposing aqueous ozone. Their catalytic activities were also evaluated by using the fixed bed column method. When alkali cations were removed by acid rinsing or substituted by alkali-earth cations, the catalytic activities was significantly deteriorated. These results suggest that the metal cations on the crystal surface of the hydrophilic zeolite would play a key role for catalytic activity for decomposing aqueous ozone. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  7. Impact protection behavior of a mordenite zeolite system

    Science.gov (United States)

    Xu, J.; Hu, R.; Chen, X.; Hu, D.

    2016-05-01

    By combining zeolite with water, a novel nanocomposite may exhibit extraordinary capability of energy absorption and impact mitigation. The multiple size of zeolite may lead to simultaneous yet different infiltration behaviors of water molecules, and thus multi-staged energy mitigation characteristics (which may benefit the scope of application). In this study, we investigate the dynamic infiltration behavior of water into mordenite zeolite (MOR) using molecular dynamics (MD) simulations. Thanks to its hydrophobicity and multi pore-sized structure, the MOR system has a decent energy mitigation performance upon high impact speed. Parametric studies are carried out to investigate the effects of various parameters, including the impact speed, mass, and water/zeolite ratio, on energy mitigating characteristics. The MOR/water mixture may perform better at a higher impact energy with higher MOR zeolite-water ratio. Upon unloading, the defiltration of water molecules is faster and more complete at higher impact speed. Results may guide the design and application of the energy mitigation nanosystem.

  8. Recent Advances on Bioethanol Dehydration using Zeolite Membrane

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Dharmawijaya, P. T.; Wenten, I. G.

    2017-07-01

    Renewable energy has gained increasing attention throughout the world. Bioethanol has the potential to replace existing fossil fuel usage without much modification in existing facilities. Bioethanol which generally produced from fermentation route produces low ethanol concentration. However, fuel grade ethanol requires low water content to avoid engine stall. Dehydration process has been increasingly important in fuel grade ethanol production. Among all dehydration processes, pervaporation is considered as the most promising technology. Zeolite possesses high potential in pervaporation of bioethanol into fuel grade ethanol. Zeolite membrane can either remove organic (ethanol) from aqueous mixture or water from the mixture, depending on the framework used. Hydrophilic zeolite membrane, e.g. LTA, can easily remove water from the mixture leaving high ethanol concentration. On the other hand, hydrophobic zeolite membrane, e.g. silicate-1, can remove ethanol from aqueous solution. This review presents the concept of bioethanol dehydration using zeolite membrane. Special attention is given to the performance of selected pathway related to framework selection.

  9. Dissolution of Iron During Biochemical Leaching of Natural Zeolite

    Directory of Open Access Journals (Sweden)

    Lengauer C.

    2004-12-01

    Full Text Available Natural zeolite, including clinoptilolite, often contains iron and manganese which decrease the whiteness of this sharp angular material.The biological treatment of zeolite enables its use as an substitute for tripolyphosphates in wash powders which have to comply with strict requirements as far as whiteness is concerned and rounded off grain content. Insoluble Fe3+ and Mn4+ in the zeolite could be reduced to soluble Fe2+ and Mn2+ by silicate bacteria of Bacillus spp. These metals were efficiently removed from zeolite as documented by Fe2O3 decrease (from 1.37% to 1.08% and MnO decrease (from 0.022% to 0.005% after bioleaching. The whiteness of zeolite was increased by 8%. The leaching effect, observed by scanning electron microscopy, caused also a chamfer of the edges of sharp angular grains. Despite the enrichment by fine-grained fraction, the decrease of the surface area of clinoptilolite grains from the value 24.94 m2/g to value 22.53 m2/g was observed. This fact confirms the activity of bacteria of Bacillus genus in the edge corrosion of mineral grains.Removal of iron and manganese as well as of sharp edges together with the whiteness increase would provide a product suitable for industrial applications.

  10. Zeolite and wollastonite synthesis from rice hull ash

    International Nuclear Information System (INIS)

    Fernandes, Alberto de Andrade

    2006-01-01

    Rice hull ash (RHA) is a industry scrap rich in amorphous silica. A simple and low-energy cost method for the extraction of this silica was researched. A low level of impurity and high reactivity material was produced, which is appropriate for the synthesis of zeolites and wollastonite (CaSiO 3 ). The synthetic zeolites has not similar structures in nature, and they have been more and more valued in the market due to their purity and efficiency in specific applications like ion exchange, molecular sieve and catalysis areas. High purity wollastonite has many applications in manufacturing and agriculture. The mineral wollastonite can be formed in nature in different ways; it is generally accepted two forming processes, both encompassing limestone metamorphism (heat and pressure). In this work, a new process for the synthesis of zeolites and wollastonite from RHA colloidal silica was developed. Moreover, the process is aimed at lower energy costs, fewer stages and fewer reactants consume. In this work, zeolite A used in detergent and zeolite ZSM-5, employed in the petrochemical industry due to its high selectivity in catalytic reactions and its high thermo and acid stability, were synthesized. The first step of the wollastonite synthesis was studied, with the purpose of obtaining calcium hydrosilicate. Eleven different hydrosilicates occur in the system Ca(OH) 2 -SiO 2 -H 2 O, in the second step it was annealed to form the wollastonite phase. (author)

  11. Colorimetric characterization of LCD based on constrained least squares

    Science.gov (United States)

    LI, Tong; Xie, Kai; Wang, Qiaojie; Yao, Luyang

    2017-01-01

    In order to improve the accuracy of colorimetric characterization of liquid crystal display, tone matrix model in color management modeling of display characterization is established by using constrained least squares for quadratic polynomial fitting, and find the relationship between the RGB color space to CIEXYZ color space; 51 sets of training samples were collected to solve the parameters, and the accuracy of color space mapping model was verified by 100 groups of random verification samples. The experimental results showed that, with the constrained least square method, the accuracy of color mapping was high, the maximum color difference of this model is 3.8895, the average color difference is 1.6689, which prove that the method has better optimization effect on the colorimetric characterization of liquid crystal display.

  12. Statistical mechanics of budget-constrained auctions

    International Nuclear Information System (INIS)

    Altarelli, F; Braunstein, A; Realpe-Gomez, J; Zecchina, R

    2009-01-01

    Finding the optimal assignment in budget-constrained auctions is a combinatorial optimization problem with many important applications, a notable example being in the sale of advertisement space by search engines (in this context the problem is often referred to as the off-line AdWords problem). On the basis of the cavity method of statistical mechanics, we introduce a message-passing algorithm that is capable of solving efficiently random instances of the problem extracted from a natural distribution, and we derive from its properties the phase diagram of the problem. As the control parameter (average value of the budgets) is varied, we find two phase transitions delimiting a region in which long-range correlations arise

  13. Experimental Determination of the Molar Absorption Coefficient of n-Hexane Adsorbed on High-Silica Zeolites.

    Science.gov (United States)

    Gatti, Giorgio; Olivas Olivera, Diana F; Sacchetto, Vittoria; Cossi, Maurizio; Braschi, Ilaria; Marchese, Leonardo; Bisio, Chiara

    2017-09-06

    Determination of the molar absorption coefficients of the CH 3 bending mode at ν˜ =1380 cm -1 (ϵ 1380 ) of n-hexane adsorbed from the gas phase on two different dealuminated zeolites is derived by a combination of IR spectroscopy and microgravimetric analysis. High-silica zeolite Y (HSZ-Y) and zeolite ZSM-5 (with SiO 2 /Al 2 O 3 ratios of 200 and 280, respectively) with different textural and surface features are selected to evaluate the effect of the pore structure and architecture on the value of ϵ 1380 of the adsorbed n-hexane. Experimental data indicate that the molecule experiences a different adsorption environment inside zeolites; thus resulting in a significant change of the dipole moment and very different ϵ 1380 values: (0.278±0.018) cm μmol -1 for HSZ-Y and (0.491±0.032) cm μmol -1 for ZSM-5. Experimental data are also supported by computational modeling, which confirms the effect of different matrices on the IR absorption intensity. This study reveals that the use of probe molecules for quantitative measurements of surface sites has to be judiciously adopted, especially if adsorption occurs in the restricted spaces of microporous materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Trends in PDE constrained optimization

    CERN Document Server

    Benner, Peter; Engell, Sebastian; Griewank, Andreas; Harbrecht, Helmut; Hinze, Michael; Rannacher, Rolf; Ulbrich, Stefan

    2014-01-01

    Optimization problems subject to constraints governed by partial differential equations (PDEs) are among the most challenging problems in the context of industrial, economical and medical applications. Almost the entire range of problems in this field of research was studied and further explored as part of the Deutsche Forschungsgemeinschaft (DFG) priority program 1253 on “Optimization with Partial Differential Equations” from 2006 to 2013. The investigations were motivated by the fascinating potential applications and challenging mathematical problems that arise in the field of PDE constrained optimization. New analytic and algorithmic paradigms have been developed, implemented and validated in the context of real-world applications. In this special volume, contributions from more than fifteen German universities combine the results of this interdisciplinary program with a focus on applied mathematics.   The book is divided into five sections on “Constrained Optimization, Identification and Control”...

  15. Constraining spacetime torsion with LAGEOS

    Science.gov (United States)

    March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone

    2011-11-01

    We compute the corrections to the orbital Lense-Thirring effect (or frame-dragging) in the presence of spacetime torsion. We analyze the motion of a test body in the gravitational field of a rotating axisymmetric massive body, using the parametrized framework of Mao, Tegmark, Guth and Cabi. In the cases of autoparallel and extremal trajectories, we derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of Celestial Mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter. We also show how the LAser GEOdynamics Satellites (LAGEOS) can be used to constrain torsion parameters. We report the experimental constraints obtained using both the nodes and perigee measurements of the orbital Lense-Thirring effect. This makes LAGEOS and Gravity Probe B complementary frame-dragging and torsion experiments, since they constrain three different combinations of torsion parameters.

  16. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    Science.gov (United States)

    Nicholas, Christpher P; Boldingh, Edwin P

    2013-12-17

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and show to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hyrdocarbons into hydrocarbons removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  17. Nondestructive depth profiling of rare-earth and actinide zeolites via Rutherford backscattering methods

    International Nuclear Information System (INIS)

    Baumann, S.A.; Strathman, M.D.; Suib, S.L.

    1988-01-01

    Rutherford backscattering (RBS) methods have been used to study rare-earth and actinide-ion-exchanged small pore (A) and large pore (Y) zeolites. A theoretical discussion of the RBS method and a novel method of data treatment are given. Experimental data for zeolites have been simulated and theoretical depth profiles have been determined. Both experimental and theoretical data suggest that uranyl-exchanged A zeolite has a large uranium to oxygen surface ratio while the corresponding Y zeolite has a large uranium to oxygen bulk ratio. Relative atomic fractions of all zeolite elements are also given

  18. Water and water vapor sorption studies in polypropylene-zeolite composites

    OpenAIRE

    Pehlivan, H.; Özmıhçı, Filiz; Tıhmınlıoğlu, Funda; Balköse, Devrim; Ülkü, Semra

    2003-01-01

    Water and water vapor sorption to porous polypropylene-zeolite composites prepared by hot pressing have been studied as a function of zeolite loading. This work presents the first report on the effect of the zeolite as a filler on the water-sorption properties of PP composites. Water swelling experiments were conducted at 25°C using pure PP and PP-zeolite films samples having different zeolite loadings (6-40 wt %). Because PP is a hydrophobic polymer, it does not sorp any water, but the compo...

  19. Recent progress in the direct synthesis of hierarchical zeolites: synthetic strategies and characterization methods

    KAUST Repository

    Liu, Zhaohui

    2017-06-16

    Hierarchically structured zeolites combine the merits of microporous zeolites and mesoporous materials to offer enhanced molecular diffusion and mass transfer without compromising the inherent catalytic activities and selectivity of zeolites. This short review gives an introduction to the synthesis strategies for hierarchically structured zeolites with emphasis on the latest progress in the route of ‘direct synthesis’ using various templates. Several characterization methods that allow us to evaluate the ‘quality’ of complex porous structures are also introduced. At the end of this review, an outlook is given to discuss some critical issues and challenges regarding the development of novel hierarchically structured zeolites as well as their applications.

  20. Loading and leakage of krypton immobilized in zeolites and glass

    International Nuclear Information System (INIS)

    Christensen, A.B.; Del Debbio, J.A.; Knecht, D.A.; Tanner, J.E.

    1980-01-01

    Krypton-85 is formed in nuclear power reactors and remains trapped until the fuel is reprocessed. Federal regulations limit the release of 85 Kr to the environment, requiring recovery and storage of 85% of the 85 Kr produced in commercial light-water reactors after January 1, 1983. One of the long-term storage options involves encapsulating 85 Kr in zeolites or glasses at high pressure and temperature. This paper presents experimental results for krypton encapsulation and leakage in sodalite, zeolite 5A, and Vycor Thristy glass. The results show that all three materials are feasible for 85 Kr immobilization and long-term storage, although zeolite 5A and Thirsty Vycor are preferable due to lower leakage rates

  1. Methanol conversion to lower olefins over RHO type zeolite

    KAUST Repository

    Masih, Dilshad

    2013-07-01

    Eight-membered ring small-pore zeolite of RHO-type topology has been synthesized, characterized and tested for methanol-to-olefin (MTO) reaction. The zeolite was hydrothermally crystallized from the gel with Si/Al ratio of 5.0. It showed a high BET specific surface area (812 m2 g-1), micropore volume (0.429 cm3 g-1), and acid amount (2.53 mmol g-1). Scanning electron microscopy observations showed small crystallites of about 1 μm. The zeolite was active for MTO reaction with 100% methanol conversions at 623-723 K, whereas selectivity to lower olefins changed with time. © 2013 Elsevier B.V.

  2. Synthesis and Evaluation of Zeolite Surface-Modified Perlite

    Directory of Open Access Journals (Sweden)

    Kasai Makoto

    2017-01-01

    Full Text Available Perlite is volcanic glass mainly composed of amorphous aluminum silicate, mainly composed SiO2 and Al2O3 with less impurities such as heavy metals. Amorphous (glassy perlite is used in lightweight aggregate and insulation. In addition, it has also been used as a filter aid by grinding the expanded perlite. However, it has not been used as environmental cleanup materials, because the ion exchange capacity of the perlite is very low. In this study, we tried to synthesize the hybrid filter aid with chemical adsorption capacity by synthesizing the zeolite on the surface of the perlite. As a result, by using the hydrothermal synthesis method, zeolite surface modified perlite was synthesized in which the LTA type zeolites were generated on the surface of the perlite.

  3. Mesoporous Zeolite Single Crystals for Catalytic Hydrocarbon Conversion

    DEFF Research Database (Denmark)

    Schmidt, I.; Christensen, Claus H.; Kustova, Marina

    2005-01-01

    Recently, mesoporous zeolite single crystals were discovered. They constitute a novel family of materials that features a combined micropore and mesopore architecture within each individual crystal. Here, we briefly summarize recent catalytic results from cracking and isomerization of alkalies......, alkylation of aromatics and present new results on isomerization of aromatics. Specifically, the shape-selective isomerization of meta-xylenc into para-xylene and ortho-xylene is studied. In all these reactions, rnesoporous zeolite single crystals prove to be unique catalysts since they provide easy...... transport to and from active sites and at the same time maintain the shape-selectivity required. Thus, all these results support the idea that the beneficial effect of the mesopores system in the mesoporous zeolite single crystals call be solely attributed to enhanced mass transport....

  4. The zeolite mediated isomerization of allyl phenyl ether

    Science.gov (United States)

    Pebriana, R.; Mujahidin, D.; Syah, Y. M.

    2017-04-01

    Allyl phenyl ether is an important starting material in organic synthesis that has several applications in agrochemical industry. The green transformation of allyl phenyl ether assisted by heterogeneous catalyst is an attractive topic for an industrial process. In this report, we investigated the isomerization of allyl phenyl ether by heating it in zeolite H-ZSM-5 and Na-ZSM-5. The conversion of allyl phenyl ether (neat) in H-ZSM-5 was 67% which produced 40% of 2-allylphenol, 17% of 2-methyldihydrobenzofuran, and other product (4:1.7:1), while in Na-ZSM-5 produced exclusively 2-allylphenol with 52% conversion. These results showed that zeolite properties can be tuned to give a selective transformation by substitution of metal ion into the zeolite interior.

  5. Evaluation of paddy quality dried with zeolite under medium temperature

    Science.gov (United States)

    Irfandy, F.; Djaeni, M.

    2018-01-01

    Drying becomes important role to obtain good quality product in post-harvest treatment for paddy. Adsorption drying process taken place on medium operation temperature can be an option to enhance paddy quality. The aim of this study was to evaluate the quality of paddy dried with zeolite as adsorbent. In case, paddy from local farmer in Semarang was dried from initial moisture content 23% (wet basis) under different temperature 40 and 60°C, both with and without zeolite. Moisture content was observed by gravimetry every 15 minutes during 60 minutes drying time. Furthermore, the quality of paddy represented by percentage of head rice and proximate was analyzed after drying process completed. Results showed that compared to conventional drying without zeolite, the adsorption dryer was more superior in term of drying time as well as product quality improvement and there are no much differences in proximate analyzed result.

  6. Zeolites as Catalysts for Fuels Refining after Indirect Liquefaction Processes

    Directory of Open Access Journals (Sweden)

    Arno de Klerk

    2018-01-01

    Full Text Available The use of zeolite catalysts for the refining of products from methanol synthesis and Fisher–Tropsch synthesis was reviewed. The focus was on fuels refining processes and differences in the application to indirect liquefaction products was compared to petroleum, which is often a case of managing different molecules. Processes covered were skeletal isomerisation of n-butenes, hydroisomerisation of n-butane, aliphatic alkylation, alkene oligomerisation, methanol to hydrocarbons, ethanol and heavier alcohols to hydrocarbons, carbonyls to hydrocarbons, etherification of alkenes with alcohols, light naphtha hydroisomerisation, catalytic naphtha reforming, hydroisomerisation of distillate, hydrocracking and fluid catalytic cracking. The zeolite types that are already industrially used were pointed out, as well as zeolite types that have future promise for specific conversion processes.

  7. Improvement of adsorption properties of zeolites and their characterization - 15133

    International Nuclear Information System (INIS)

    Mimura, H.; Rahman, M.S.; Yamagishi, I.; Matsukura, M.; Kuroda, A.

    2015-01-01

    The improvement of adsorption properties of radioactive Cs and Sr was evaluated for different kinds of zeolites treated with various methods; calcination, conditioning, surface alteration, fine-granulation, mixture-granulation, honeycomb modeling and loading. Their characteristics were examined by instrumental analyses (SEM, EPMA, XRD, IR) and batch and column adsorption methods. As for the calcination treatment, the calcined natural mordenite was prepared by heat treatment at different temperatures up to 1000 C. degrees. The improvement of adsorption rate was observed for the calcined mordenite at 500 C. degrees. The conditioning with H + , Na + and K + ions was ineffective for the enhancement of adsorption properties of mordenites. Comparing the adsorption properties of Sr 2+ for A-type zeolites having various particle sizes, the adsorption kinetics tended to increase with decreasing particle size in the order of A powder > A0.5(0.5 mm) > A0.5HP(0.5 mm) > A1.5(1.5 mm). In particular, A0.5HP with no binder exhibited a relatively large uptake (%) of Sr 2+ above 80% in seawater, which is the largest value in the conventional granular zeolites. For multi-nuclide decontamination, composite zeolites such as AMXα and AMXβ were prepared by mixing three kinds of zeolites; A zeolite, Mordenite and X zeolite. The mixing ratios of AMXα and AMXβ were 1: 1: 1 and 0.5: 1: 0.5, respectively. Composite zeolites had relatively large uptake (%) above 95% for Cs + , Sr 2+ and Co 2+ ions in 1/10 diluted seawater. Zeolites honeycomb can be used for the continuous concentration of Cs + and Sr 2+ ions in seawater. Uptake (%) of Cs + ions for mordenite honeycomb at V/m= 100 cm 3 /g was estimated to be 86.8% and 57.9% within 18 h in pure water and 15 h in seawater, respectively. Uptake (%) of Sr 2+ ions for A-type zeolite honeycomb was estimated to be 99.2% within 24 h and 69.0% within 3 h in pure water and seawater, respectively. As for the Cs adsorption on mordenite honeycomb at a

  8. Selective reduction of NO over copper-containing modified zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Halasz, J.; Varga, J.; Schoebel, G.; Kiricsi, I.; Hernadi, K.; Hannus, I.; Varga, K.; Fejes, P. [Applied Chemistry Dept., Jozsef Attila Univ., Szeged (Hungary)

    1995-12-31

    The most efficient method for NO removal from stationary and mobile sources is catalytic reduction with ammonia, hydrocarbons, CO or H{sub 2}. Modified zeolites are active catalysts in these processes. For Cu-ZSM-5 especially high activity and stability have been reported. In this work the properties of copper-containing ZSM-5 zeolites prepared by wet or solid state ion-exchange have been investigated. The Broensted acidity of the Cu{sup 2+}-exchanged samples was much lower than that of the parent zeolites, and they had high activity in selective reduction with ammonia, propene or propane. A comparison of Cu-ZSM-5 activity in the decomposition of NO and in the reaction of NO with propene or propane revealed that the hydrocarbons as well as the nitrogen oxides play important roles in the performance of NO reduction catalysis. 8 figs., 1 tab., 16 refs.

  9. D2-H2 equilibration over γ-irradiated zeolites

    International Nuclear Information System (INIS)

    Novakova, J.; Wichterlova, B.

    1987-01-01

    D 2 -H 2 equilibration was studied at 77 and 298 K over HY, AlHY, HZSM-5 and Alsub(x)Osub(y)HZSM-5 zeolites which had been γ-irradiated at 77 and/or 298 K. The exchange rate was found to be higher at the lower temperature regardless of the temperature of irradiation. Moreover, at 77 K the exchange rates were similar and more stable over the individual zeolites than at 298 K, thus indicating a common reaction path at 77 K. The exchange rate at 298 K depended on the zeolite type: it was more stable and higher over HZSM-5 than over HY, and extra-lattice Al increased both these properties on HY as well as on HZSM-5. The reaction mechanism is discussed in connection with the nature of defects generated by γ-irradiation. (author)

  10. On gauge fixing and quantization of constrained Hamiltonian systems

    International Nuclear Information System (INIS)

    Dayi, O.F.

    1989-06-01

    In constrained Hamiltonian systems which possess first class constraints some subsidiary conditions should be imposed for detecting physical observables. This issue and quantization of the system are clarified. It is argued that the reduced phase space and Dirac method of quantization, generally, differ only in the definition of the Hilbert space one should use. For the dynamical systems possessing second class constraints the definition of physical Hilbert space in the BFV-BRST operator quantization method is different from the usual definition. (author). 18 refs

  11. Novel modified zeolites for energy-efficient hydrocarbon separations.

    Energy Technology Data Exchange (ETDEWEB)

    Arruebo, Manuel (University of Colorado, Boulder, CO); Dong, Junhang; Anderson, Thomas (Burns and McDonnell, Kansas City, MO); Gu, Xuehong; Gray, Gary (Goodyear Chemical Company, Akron, OH); Bennett, Ron (Goodyear Chemical Company, Akron, OH); Nenoff, Tina Maria; Kartin, Mutlu; Johnson, Kaylynn (Goodyear Chemical Company, Akron, OH); Falconer, John (University of Colorado, Boulder, CO); Noble, Richard (University of Colorado, Boulder, CO)

    2006-11-01

    We present synthesis, characterization and testing results of our applied research project, which focuses on the effects of surface and skeletal modification of zeolites for significant enhancements in current hydrocarbon (HC) separations. Zeolites are commonly used by the chemical and petroleum industries as catalysts and ion-exchangers. They have high potential for separations owing to their unique pore structures and adsorption properties and their thermal, mechanical and chemical properties. Because of zeolites separation properties, low cost, and robustness in industrial process, they are natural choice for use as industrial adsorbents. This is a multidisciplinary effort to research, design, develop, engineer, and test new and improved materials for the separation of branched vs. linear organic molecules found in commercially important HC streams via adsorption based separations. The focus of this project was the surface and framework modification of the commercially available zeolites, while tuning the adsorption properties and the selectivities of the bulk and membrane separations. In particular, we are interested with our partners at Goodyear Chemical, on how to apply the modified zeolites to feedstock isoprene purification. For the characterization and the property measurements of the new and improved materials powder X-ray diffraction (PXRD), Residual Gas Analyzer-Mass Spectroscopy (RGA-MS), Electron Microscopy (SEM/EDAX), temperature programmed desorption (TPD) and surface area techniques were utilized. In-situ carbonization of MFI zeolite membranes allowed for the maximum separation of isoprene from n-pentane, with a 4.1% enrichment of the binary stream with n-pentane. In four component streams, a modified MFI membrane had high selectivities for n-pentane and 1-3-pentadiene over isoprene but virtually no separation for the 2-methyl-2-butene/isoprene pair.

  12. Regeneration of clinoptilolite zeolite used for the ammonium removal

    International Nuclear Information System (INIS)

    Garcia G, M.C.

    2002-01-01

    The use of zeolites has been increased in the last years with different applications and with a great boom in the environmental area, but a little had been make about the regeneration of such zeolites. The presence of nitrogen-ammonia in water may cause serious pollution problems since it results to be toxic for fishes and other aquatic life forms, also it provokes the algae growing. The natural clinoptilolite contains interchangeable ions such as the sodium (Na + ), potassium (K + ), magnesium (Mg 2+ ) and calcium (Ca 2+ ) in different proportions depending on the mineral origin When the zeolite is upgraded to its sodium form, the cation exchange capacity and the preference by the nitrogen-ammonia are increased, allowing the reversible process of sorption. In this work it was proposed the regeneration to its sodium form about the ammonia clinoptilolite zeolite. The natural mineral was characterized using the methods such as: X-ray diffraction, Infrared spectroscopy, Thermal gravimetric analysis and surface area. The results show that the ammonium sorption was between 95% and 98.7% such an ambient temperature as a flow back. the zeolite was regenerated approximately from 60% in the first cycle up to 97% in the last cycle at flow back temperature and of 59.2% up to 96.9% at ambient temperature, it was not presented any significant effect which could be attributed to the temperature. During the exchange process, the cations present in the natural zeolite were exchanged with the ammonium ions, this process was not completed due to that retained ammonium quantity was major that of the desorpted ions, what shows that in addition of ion exchange, another type of sorption process exists. (Author)

  13. Copper removal using bio-inspired polydopamine coated natural zeolites

    International Nuclear Information System (INIS)

    Yu, Yang; Shapter, Joseph G.; Popelka-Filcoff, Rachel; Bennett, John W.; Ellis, Amanda V.

    2014-01-01

    Highlights: • Natural zeolites were modified with bio-inspired polydopamine. • A 91.4% increase in Cu(II) ion adsorption capacity was observed. • Atomic absorption and neutron activation analysis gave corroborative results. • Neutron activation analysis was used to provide accurate information on 30+ elements. • Approximately 90% of the adsorbed copper could be recovered by 0.1 M HCl treatment. - Abstract: Herein, for the first time, natural clinoptilolite-rich zeolite powders modified with a bio-inspired adhesive, polydopamine (PDA), have been systematically studied as an adsorbent for copper cations (Cu(II)) from aqueous solution. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) revealed successful grafting of PDA onto the zeolite surface. The effects of pH (2–5.5), PDA treatment time (3–24 h), contact time (0 to 24 h) and initial Cu(II) ion concentrations (1 to 500 mg dm −3 ) on the adsorption of Cu(II) ions were studied using atomic absorption spectroscopy (AAS) and neutron activation analysis (NAA). The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. The maximum adsorption capacities of Cu(II) were shown to be 14.93 mg g −1 for pristine natural zeolite and 28.58 mg g −1 for PDA treated zeolite powders. This impressive 91.4% increase in Cu(II) ion adsorption capacity is attributed to the chelating ability of the PDA on the zeolite surface. Furthermore studies of recyclability using NAA showed that over 50% of the adsorbed copper could be removed in mild concentrations (0.01 M or 0.1 M) of either acid or base

  14. [Biodegradation and adsorption of bio-zeolite on pyridine and quinoline].

    Science.gov (United States)

    Bai, Yao-Hui; Sun, Qing-Hua; Xing, Rui; Wen, Dong-Hui; Tang, Xiao-Yan

    2010-09-01

    The study was to explore the treatment of pyridine, quinoline and their transformation product, NH(4+) -N, by the biodegradation and adsorption of a natural and a modified bio-zeolites. The experiment results demonstrated that the mixed bacteria on the bio-zeolites, a pyridine-degrading bacterium and a quinoline-degrading bacterium, could degrade pyridine and quinoline simultaneously. The NH(4+) -N transformed from pyridine and quinoline could be adsorbed by the natural and modified zeolites. The adsorption capacity of the modified zeolite was lower than that of the natural zeolite. However, more microorganisms could attach on the surface of the modified zeolite, so the application of the modified bio-zeolite has a better prospect in actual treatment of pyridine and/ or quinoline pollution.

  15. Adsorpsi Ion Logam Tembaga Menggunakan Nano Zeolit Alam yang Diaktivasi

    OpenAIRE

    Yulianis Yulianis; Mahidin Mahidin; Syaifullah Muhammad

    2017-01-01

    This study was aimed to find out the ability of natural zeolite coming from Blang Pidie, South West Aceh District, Aceh Province, Indonesia, which was applied as an adsorbent to adsorp heavy metal copper (Cu²⁺) ions in aqueous solution. This research was conducted to enhance the performance of natural zeolite by downsizing it to nano particles, then activated physically and chemically using 0.05 M HCl, then calcined at temperature 350°C for 2 hours. Test of Cu²⁺ metal ion adsorption to nano n...

  16. Deuteration of piperylene on zeolite NaY

    International Nuclear Information System (INIS)

    Kharlamov, V.V.; Kadentsev, V.I.; Kharatishvili, N.G.; Minachev, Kh.M.

    1982-01-01

    In order to further refine the mechanism of hydrogenation reaction on zeolites, the deuteration of piperylene on NaY was studied. The kinetic isotope effect in the hydrogenation of piperylene on zeolite NaY indicates that hydrogen takes part in the limiting step of the process and the 1-pentene and 2-pentene formed in the deuteration of piperylene have a wide isotope distribution, with a maximum amount of the d 2 isotope, and an average number of deuterium atoms in the molecules equal to 2.25-2.36

  17. Nonlinear upconversion based infrared spectroscopy on ZSM-5 zeolite

    DEFF Research Database (Denmark)

    Kehlet, Louis Martinus; Beato, Pablo; Tidemand-Lichtenberg, Peter

    2017-01-01

    We present a spectroscopic measurement of zeolite ZSM-5 in the mid-IR following the methanol attachment to active sites at 200 °C. The spectra are measured using nonlinear frequency upconversion to the near-IR spectral region.......We present a spectroscopic measurement of zeolite ZSM-5 in the mid-IR following the methanol attachment to active sites at 200 °C. The spectra are measured using nonlinear frequency upconversion to the near-IR spectral region....

  18. Method for encapsulating nanoparticles in a zeolite matrix

    Science.gov (United States)

    Coker, Eric N.

    2007-12-11

    A method for preparing a metal nanocluster composite material. A porous zeolitic material is treated with an aqueous metal compound solution to form a metal ion-exchanged zeolitic material, heated at a temperature ramp rate of less than 2.degree. C./min to an elevated temperature, cooled, contacted with an organic monomer and heating to induce polymerization, and heating the composite material to greater than 350.degree. C. under non-oxidizing conditions to form a metal nanocluster-carbon composite material with nanocluster sizes between approximately 0.6 nm and 10 nm.

  19. Effect of zeolite on health condition of canines

    Directory of Open Access Journals (Sweden)

    Vučićević Ivana

    2008-01-01

    Full Text Available The paper shows the results of investigations of elementary hematological and biochemical blood parameters of German Shepherd dogs administered zeolite through feed daily for a period of 50 days. No undesired effects were established during the period of observation, and in fact there was a full normalization of the condition of the dogs that previously exhibited transitory symptoms of gastrointestinal tract disorders. No significant digressions were observed in the examined biochemical parameters of blood, either, that could indicate any harmful effects of zeolite, with the exception of the tendency toward a reduction in the concentrations of phosphorus and calcium, which was not manifest clinically as well during this period.

  20. Zeolite-like metal-organic frameworks with ana topology

    KAUST Repository

    Eddaoudi, Mohamed

    2017-04-20

    Embodiments of the present disclosure describe a zeolite-like metal-organic framework composition comprising a metal-organic framework composition with ana topology characterized by the formula [MIII(4, 5-imidazole dicarboxylic acid)2X(solvent)a]n wherein MIII comprises a trivalent cation of a rare earth element, X comprises an alkali metal element or alkaline earth metal element, and solvent comprises a guest molecule occupying pores. Embodiments of the present disclosure describe a method of separating paraffins comprising contacting a zeolite-like metal-organic framework with ana topology with a flow of paraffins, and separating the paraffins by size.

  1. Investigation of Y, FAU-zeolites containing rare earth cations

    International Nuclear Information System (INIS)

    Gardos, G.; De Jonge, A.; Halmos, F.; Kristof, J.; Redey, A.

    1984-01-01

    Polycationic zeolites were made of the H (NHsub(4))-Y, FAU form one. The change of Broensted acid sites was followed as a function of the pretreating temperature by infrared spectroscopy for mixed (La, Ce) form zeolites. It was stated that the 3630 cmsup(-1) absorption band can be related to the acidic OH-groups responsible for the catalytic activity in the alkylating reaction of isobutane with 1-butene, while the band at 3510 cmsup(-1) is characteristic of the non-acidic hydroxyl-groups and has no relation with the catalytic activity. (author)

  2. EFFECT OF GRAIN SIZE AND ACTIVATION TIME OF ZEOLITE TO ADSORPTION AND DESORPTION OF NH4OH AND KCL AS MODEL OF FERTILIZER-ZEOLITE MIX

    Directory of Open Access Journals (Sweden)

    Muhammad Prasantio Bimantio

    2017-10-01

    Full Text Available Zeolites can be used as adsorbent, ion exchange, catalyst, or catalyst carrier. Application of fertilizer use in the zeolite also be one of the interesting topic. Zeolites in a mixture of fertilizer can use to control the release of nutrients. The purpose of this research is to study the effect of grain size and time of the activation of zeolite to adsorption and desorption of NH4OH and KCl as modeling of ZA and KCl fertilizer, to obtain the value of adsorption rate constant (ka and desorption rate constant (kd. This research procedure include: the process of adsorption by adding zeolite with various size and time of activation into a sealed beaker glass and let the adsorption process occurs for 24 hours. After 24 hours, the solution was filtered, the zeolite then put in 100 ml of aquadest into a sealed beaker glass and let the desorption process happened for another 24 hours. Three samples with the largest difference solution concentrations looked for the value of the ka and kd. Zeolite configuration with the largest ka is trialed with fertilizer and compared with the value of ka obtained from modeling. The result for NH4OH adsorbate, -50+60 mesh 2 hours configuration zeolite give the largest ka. For KCl adsorbate, -30+40 mesh 4 hours configuration zeolite give the largest ka. The value between modeling and trials with fertilizers are not much different.

  3. Beyond Creation of Mesoporosity: The Advantages of Polymer-Based Dual-Function Templates for Fabricating Hierarchical Zeolites

    KAUST Repository

    Tian, Qiwei

    2016-02-05

    Direct synthesis of hierarchical zeolites currently relies on the use of surfactant-based templates to produce mesoporosity by the random stacking of 2D zeolite sheets or the agglomeration of tiny zeolite grains. The benefits of using nonsurfactant polymers as dual-function templates in the fabrication of hierarchical zeolites are demonstrated. First, the minimal intermolecular interactions of nonsurfactant polymers impose little interference on the crystallization of zeolites, favoring the formation of 3D continuous zeolite frameworks with a long-range order. Second, the mutual interpenetration of the polymer and the zeolite networks renders disordered but highly interconnected mesopores in zeolite crystals. These two factors allow for the synthesis of single-crystalline, mesoporous zeolites of varied compositions and framework types. A representative example, hierarchial aluminosilicate (meso-ZSM-5), has been carefully characterized. It has a unique branched fibrous structure, and far outperforms bulk aluminosilicate (ZSM-5) as a catalyst in two model reactions: conversion of methanol to aromatics and catalytic cracking of canola oil. Third, extra functional groups in the polymer template can be utilized to incorporate desired functionalities into hierarchical zeolites. Last and most importantly, polymer-based templates permit heterogeneous nucleation and growth of mesoporous zeolites on existing surfaces, forming a continuous zeolitic layer. In a proof-of-concept experiment, unprecedented core-shell-structured hierarchical zeolites are synthesized by coating mesoporous zeolites on the surfaces of bulk zeolites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Evaluation of synthetic zeolite as engineering passive permeable reactive barrier

    International Nuclear Information System (INIS)

    Ibrahim, O.A.A.

    2011-01-01

    The presence of toxic pollutants in groundwater brings about significant changes in the properties of water resources and has to be avoided in order to preserve the environmental quality. Heavy metals are among the most dangerous inorganic water pollutants, that related to many anthropogenic sources and their compounds are extremely toxic. The treatment of contaminated groundwater is among the most difficult and expensive environmental problems. Over the past years, permeable reactive barriers have provided an increasingly important role in the passive insitu treatment of contaminated groundwater. There are a large number of materials that are able to immobilize contaminants by sorption, including granulated active carbon, zeolite, montmorillonite, peat, compost, sawdust, etc. Zeolite X is a synthetic counterpart of the naturally occurring mineral Faujasite. It has one of the largest cavities and cavity entrances of any known zeolites. The main aim of this work is to examine the possibility of using synthetic zeolite X as an engineering permeable reactive barrier to remove heavy metals from a contaminated groundwater. Within this context, the following investigations were carried out: 1. Review on the materials most commonly used as engineered permeable reactive barriers to identify the important features to be considered in the examination of the proposed permeable reactive barrier material (zeolite X). 2. Synthesis of zeolite X and characterization of the synthesized material using different techniques. 3. Batch tests were carried out to characterize the equilibrium and kinetic sorption properties of the synthesized zeolite X towards the concerned heavy metals; zinc and cadmium ions. 4. Column tests were also performed to determine the design factors for permeable reactive barrier against zinc and cadmium ions solutions.Breakthrough curves measured in such experiments used to determine the hydrodynamic dispersion coefficients for both metal ions. 5. Analytical

  5. Disposal of Kr-85 in compressed gas cylinders and in zeolites; application of the zeolite method to other radioactive gases

    International Nuclear Information System (INIS)

    Penzhorn, R.D.

    1983-01-01

    Ultimate storage of Kr-85 in compressed gas cylinders of structural steel or austenic special steels is possible for the required storage time of 100 years at temperatures of up to 200 0 C, since Rb corrosion under ultimate storage conditions may be neglected. When Kr is stored in CaNaA zeolite at temperatures from 340-650 0 C, the pressure is of secondary importance. CO 2 and CH 4 can also be durably solidified in zeolites 4A and 5A. It is presently being assessed whether this method is applicable to T and J-129. (DG) [de

  6. Space space space

    CERN Document Server

    Trembach, Vera

    2014-01-01

    Space is an introduction to the mysteries of the Universe. Included are Task Cards for independent learning, Journal Word Cards for creative writing, and Hands-On Activities for reinforcing skills in Math and Language Arts. Space is a perfect introduction to further research of the Solar System.

  7. Coherent states in constrained systems

    International Nuclear Information System (INIS)

    Nakamura, M.; Kojima, K.

    2001-01-01

    When quantizing the constrained systems, there often arise the quantum corrections due to the non-commutativity in the re-ordering of constraint operators in the products of operators. In the bosonic second-class constraints, furthermore, the quantum corrections caused by the uncertainty principle should be taken into account. In order to treat these corrections simultaneously, the alternative projection technique of operators is proposed by introducing the available minimal uncertainty states of the constraint operators. Using this projection technique together with the projection operator method (POM), these two kinds of quantum corrections were investigated

  8. Constrained minimization in C ++ environment

    International Nuclear Information System (INIS)

    Dymov, S.N.; Kurbatov, V.S.; Silin, I.N.; Yashchenko, S.V.

    1998-01-01

    Based on the ideas, proposed by one of the authors (I.N.Silin), the suitable software was developed for constrained data fitting. Constraints may be of the arbitrary type: equalities and inequalities. The simplest of possible ways was used. Widely known program FUMILI was realized to the C ++ language. Constraints in the form of inequalities φ (θ i ) ≥ a were taken into account by change into equalities φ (θ i ) = t and simple inequalities of type t ≥ a. The equalities were taken into account by means of quadratic penalty functions. The suitable software was tested on the model data of the ANKE setup (COSY accelerator, Forschungszentrum Juelich, Germany)

  9. Constraining walking and custodial technicolor

    DEFF Research Database (Denmark)

    Foadi, Roshan; Frandsen, Mads Toudal; Sannino, Francesco

    2008-01-01

    We show how to constrain the physical spectrum of walking technicolor models via precision measurements and modified Weinberg sum rules. We also study models possessing a custodial symmetry for the S parameter at the effective Lagrangian level-custodial technicolor-and argue that these models...... cannot emerge from walking-type dynamics. We suggest that it is possible to have a very light spin-one axial (vector) boson. However, in the walking dynamics the associated vector boson is heavy while it is degenerate with the axial in custodial technicolor Udgivelsesdato: 19 May...

  10. Constraining the noncommutative spectral action via astrophysical observations.

    Science.gov (United States)

    Nelson, William; Ochoa, Joseph; Sakellariadou, Mairi

    2010-09-03

    The noncommutative spectral action extends our familiar notion of commutative spaces, using the data encoded in a spectral triple on an almost commutative space. Varying a rather simple action, one can derive all of the standard model of particle physics in this setting, in addition to a modified version of Einstein-Hilbert gravity. In this Letter we use observations of pulsar timings, assuming that no deviation from general relativity has been observed, to constrain the gravitational sector of this theory. While the bounds on the coupling constants remain rather weak, they are comparable to existing bounds on deviations from general relativity in other settings and are likely to be further constrained by future observations.

  11. High-pressure alchemy on a small-pore zeolite

    Science.gov (United States)

    Lee, Y.

    2011-12-01

    While an ever-expanding variety of zeolites with a wide range of framework topology is available, it is desirable to have a way to tailor the chemistry of the zeolitic nanopores for a given framework topology via controlling both the coordination-inclusion chemistry and framework distortion/relaxation. This is, however, subjected to the ability of a zeolitic nanopore to allow the redistribution of cations-water assembly and/or insertion of foreign molecules into the pores and channels. Small-pore zeolites such as natrolite (Na16Al16Si24O80x16H2O), however, have been known to show very limited capacity for any changes in the confinement chemistry. We have recently shown that various cation-exchanged natrolites can be prepared under modest conditions from natural sodium natrolite and exhibit cation-dependent volume expansions by up to 18.5% via converting the elliptical channels into progressively circular ones. Here, we show that pressure can be used as a unique and clean tool to further manipulate the chemistry of the natrolite nanopores. Our recent crystallographic and spectroscopic studies of pressure-insertion of foreign molecules, trivalent-cation exchange under pressure, and pressure-induced inversion of cation-water coordination and pore geometry in various cation-exchanged natrolites will be presented.

  12. Mobil/Badger to market zeolite-based cumene technology

    International Nuclear Information System (INIS)

    Rotman, D.

    1993-01-01

    Badger (Cambridge, MA) and Mobil (Fairfax, VA) are ready to jointly license a new cumene technology that they say achieves higher yields and product purity than existing processes. The zeolite-based technology is scheduled to be introduced at next month's DeWitt Petrochemical Review in Houston. The Mobil/Badger technology aims to challenge the dominant position of UOP's (Des Plaines, IL) solid phosphoric acid (SPA) catalyst process - which accounts for 80%-90% of the world's cumene production. In addition, Monsanto/Kellogg's aluminum chloride-based technology has gained significant momentum since its introduction in the 1980s. And late last year, ABB Lummus Crest (Bloomfield, NJ) also began marketing a zeolite-based cumene technology. While all the technologies make cumene via the alkylation of benzene with propylene, the Mobil/Badger process uses a zeolite-containing catalyst designed by Mobil to selectively catalyze the benzene/propylene reaction, avoiding unwanted propylene oligomerization. Because the olefin reactions are so fast, says Frank A. Demers, Badger's v.p./technology development and marketing, other zeolite technologies are forced to use complex reactor arrangements to stop the propylene-propylene reactions. However, he says, 'Mobil has designed a catalyst that wants to react benzene with propylene to make cumene.'

  13. Rotational dynamics of propylene inside Na-Y zeolite cages

    Indian Academy of Sciences (India)

    We report here the quasielastic neutron scattering (QENS) studies on the dynamics of propylene inside Na-Y zeolite using triple axis spectrometer (TAS) at Dhruva reactor, Trombay. Molecular dynamics (MD) simulations performed on the system had shown that the rotational motion involves energy larger than that involved ...

  14. The effect of feeding clinoptilolite (zeolite) to laying hens

    African Journals Online (AJOL)

    The effect of feeding clinoptilolite (zeolite) to laying hens. M.D. Olver. Animal and Dairy Science Research Institute, lrene. One hundred and twenty 4-month-old, single-combed, brown. Hy-Line pullets were fed two isocaloric diets containing 16 or. 13,5o/o protein with and without 5% clinoptilolite in four.

  15. Use of natural zeolite-supplemented litter increased broiler production

    African Journals Online (AJOL)

    The aim of this study was to ascertain the influence of natural zeolite, consisting mainly of clinoptilolite and mordenite, as a component of the litter material in broiler houses on the performance of the broilers and on some litter characteristics. Live weight gain, feed consumption, feed efficiency, viability and leg and body ...

  16. Use of natural zeolite-supplemented litter increased broiler production

    African Journals Online (AJOL)

    smyo

    Abstract. The aim of this study was to ascertain the influence of natural zeolite, consisting mainly of clinoptilolite and mordenite, as a component of the litter material in broiler houses on the performance of the broilers and on some litter characteristics. Live weight gain, feed consumption, feed efficiency, viability and leg and ...

  17. Synthesis and properties of porous zeolite aluminosilicate adsorbents

    International Nuclear Information System (INIS)

    Shilina, A.S.; Milinchuk, V.K.; Burukhin, S.B.; Gordienko, A.B.

    2015-01-01

    Environmentally safe non-energy-intensive methods of the synthesis have been developed and the properties of solid inorganic nanostructured zeolite-like adsorbents of a broad spectrum have been studied. The sorption capacities of the adsorbents with respect to various components of water pollution have been determined [ru

  18. The ADOR synthesis of new zeolites: In silico investigation

    Czech Academy of Sciences Publication Activity Database

    Trachta, Michal; Nachtigal, P.; Bludský, Ota

    2015-01-01

    Roč. 243, Apr (2015), s. 32-38 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388963 Keywords : ADOR * DFT calculations * zeolites * synthesis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.312, year: 2015

  19. Nonionic emulsion-mediated synthesis of zeolite beta

    Indian Academy of Sciences (India)

    Administrator

    taining OP to obtain the emulsion system. Finally, the emulsion system was transferred to Teflon-lined stainless steel autoclaves and crystallized at 413 K for 48 h and then 443 K for 48 h. For comparison, the conventional zeolite beta synthesis was also carried out under the same crystallization conditions. Notably, when the ...

  20. Aldol condensation of furfural and acetone on zeolites

    Czech Academy of Sciences Publication Activity Database

    Kikhtyanin, O.; Kelbichová, V.; Vitvarová, Dana; Kubů, Martin; Kubička, D.

    2014-01-01

    Roč. 227, MAY 2014 (2014), s. 154-162 ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : aldol condensation * oligomerization * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  1. Intercalation chemistry of layered zeolite precursor IPC-1P

    Czech Academy of Sciences Publication Activity Database

    Mazur, Michal; Eliášová, Pavla; Roth, Wieslaw Jerzy; Čejka, Jiří

    2014-01-01

    Roč. 227, MAY 2014 (2014), s. 37-44 ISSN 0920-5861 R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : UTL germanosilicate * IPC-1P layered precursor * Two-dimensional zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  2. Regioselective nitration of aromatic substrates in zeolite cages

    Indian Academy of Sciences (India)

    Phenol is nitrated regioselectively by fuming nitric acid inside the cages of faujasite zeolites (dependent on the loading level) and a remarkable orthoselectivity is observed in solid state nitration. Toluene and chlorobenzene also containing ortho-/para-orienting substituents, undergo faster nitration, though the ...

  3. Zeolite-derived hybrid materials with adjustable organic pillars

    Czech Academy of Sciences Publication Activity Database

    Opanasenko, Maksym; Shamzhy, Mariya; Yu, F.; Zhou, W.; Morris, R. E.; Čejka, Jiří

    2016-01-01

    Roč. 7, č. 6 (2016), s. 3589-3601 ISSN 2041-6520 R&D Projects: GA ČR GP13-17593P; GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : zeolites * inorganic aluminosilicate * nanoporous materials Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 8.668, year: 2016

  4. Selective oxidation of propane over cation exchanged zeolites

    NARCIS (Netherlands)

    Xu, J.

    2005-01-01

    This thesis focuses on investigation of the fundamental knowledge on a new method for selective oxidation of propane with O2 at low temperature (< 100°C). The relation between propane catalytic selective oxidation and physicochemical properties of cation exchanged Y zeolite has been studied. An

  5. Zeolitic imidazolate frameworks for kinetic separation of propane and propene

    Science.gov (United States)

    Li, Jing; Li, Kunhao; Olson, David H.

    2014-08-05

    Zeolitic Imidazolate Frameworks (ZIFs) characterized by organic ligands consisting of imidazole ligands that are either essentially all 2-chloroimidazole ligands or essentially all 2-bromoimidazole ligands are disclosed. Methods for separating propane and propene with the ZIFs of the present invention, as well as other ZIFs, are also disclosed.

  6. Ethylene formation by dehydration of ethanol over medium pore zeolites

    Science.gov (United States)

    Gołąbek, Kinga; Tarach, Karolina A.; Filek, Urszula; Góra-Marek, Kinga

    2018-03-01

    In this work, the role of pore arrangement of 10-ring zeolites ZSM-5, TNU-9 and IM-5 on their catalytic properties in ethanol transformation were investigated. Among all the studied catalysts, the zeolite IM-5, characterized by limited 3-dimensionality, presented the highest conversion of ethanol and the highest yields of diethyl ether (DEE) and ethylene. The least active and selective to ethylene and C3 + products was zeolite TNU-9 with the largest cavities formed on the intersection of 10-ring channels. The catalysts varied, however, in lifetime, and their deactivation followed the order: IM-5 > TNU-9 > ZSM-5. The processes taking place in the microporous zeolite environment were tracked by IR spectroscopy and analysed by the 2D correlation analysis (2D COS) allowing for an insight into the nature of chemisorbed adducts and transition products of the reaction. The cage dimension was found as a decisive factor influencing the tendency for coke deposition, herein identified as polymethylated benzenes, mainly 1,2,4-trimethyl-benzene.

  7. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Xingu-Contreras, E., E-mail: nyleve-18@hotmail.com; García-Rosales, G., E-mail: gegaromx@yahoo.com.mx [Instituto Tecnológico de Toluca (Mexico); García-Sosa, I., E-mail: irma.garcia@inin.gob.mx; Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Solache-Ríos, M., E-mail: marcos.solache@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química (Mexico)

    2015-06-15

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45{sup ∘} (2θ), inferring the presence of nanocrystals of Fe{sub 2}B as identified from Mössbauer Spectroscopy. The size of these Fe{sub 2}B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %.

  8. Effect of micronized zeolite addition to lamb concentrate feeds on ...

    African Journals Online (AJOL)

    Effect of micronized zeolite addition to lamb concentrate feeds on growth performance and some blood chemistry and metabolites. ... No differences were observed between the groups in terms of blood urea nitrogen, plasma glucose, serum creatinine, triglyceride, sodium, potassium and chlorine concentration. However ...

  9. Opportunities and limitations of hydrogen storage in zeolitic clathrates

    NARCIS (Netherlands)

    Van den Berg, A.W.C.

    2006-01-01

    The feasibility of using zeolites, and more specifically the clathrasil subgroup, for hydrogen storage has been investigated by comparing their H2 loading rate and storage capacity to the technically required values. The uptake rate and capacity are determined by means of computational modelling for

  10. USE OF SYNTHETIC ZEOLITES FOR ARSENATE REMOVAL FROM POLLUTANT WATER

    Science.gov (United States)

    Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water below the current and proposed EPA MCL has been examined...

  11. Sorption of Cs-137 and Co-60 in Natural Zeolites

    International Nuclear Information System (INIS)

    Chales Suarez, G.; Moreno Alvarez, D.; Coutin Correa, D.

    1996-01-01

    The sorption of Cs-137 and Co-60 in natural zeolites under different conditions was studied. The behaviour of samples of mineral and rock from different deposit of the country was obtained and the decontamination of radioactive waters containing both radionuclides was performed; as part of the research to determine its application in the treatment of radioactive wastes in the country

  12. Rotational dynamics of propylene inside Na-Y zeolite cages

    Indian Academy of Sciences (India)

    molecules etc. Several such dependences have been under investigation [2]. We have in particular been investigating the diffusivities of hydrocarbons in Na-Y ze- olitic cages. In this context we had earlier reported the translational diffusivities of propane, acetylene and 1,3-butadiene in Na-Y zeolite [3–5]. The translational.

  13. Peculiarities of unusual electret state in porous zeolite microstructure

    Science.gov (United States)

    Bunyatova, U.; Orbukh, V. I.; Eyvazova, G. M.; Lebedeva, N. N.; Agamaliev, Z. A.; Koçum, I. C.; Ozer, M.; Salamov, B. G.

    2017-11-01

    This study explores, for the first time to our knowledge, the influence of electret state on the dielectric parameters of porous zeolite of frequencies up to 106 Hz, at room temperature and normal atmospheric pressure. The I-V characteristics with unusual hysteresis loop in the wide pressure range were measured on zeolite plates having three different material characteristics: A) plate, cut out from a monoblock natural zeolite; B) plate, modified by silver ions, and C) plate containing silver nanoparticles. Zeolite samples were exposed to an electric field (Ep = 2 kV cm-1) in an air atmosphere for 240 min. It is established, that the stability of electret state and value of the dielectric response ε‧ and ε″ for clinoptilolite Ag nanoparticles containing plates changed under influence of DC electric field. During some time the dielectric response is restored and observed unique phenomenon indicates on the electret behavior of clinoptilolite samples. These changes are observed within a few days consequently, there is long-term dynamics of the dielectric response changes. This interpretation is based on the assumption that due influence of the dc electric field part of the silver atoms in nanoparticles decays into ions and electrons.

  14. Efficacy of natural zeolite and pigments on yolk color and ...

    African Journals Online (AJOL)

    An in vivo study was conducted to evaluate pigment adsorptive ability of a natural zeolite in laying hens. This experiment was performed with three hundred sixty Hy-line W-36 strain of laying hens at 43 weeks of age. After a two weeks adaptation period, they received six experimental diets with a 3 × 2 factorial arrangement ...

  15. Computer Simulation of Zeolites : Adsorption, Diffusion and Dealumination

    NARCIS (Netherlands)

    Ban, S.

    2009-01-01

    Zeolites are microporous materials with pores that have about the same size as small molecules like water or benzene. They are important catalysts in the petrochemical industry, for example for catalytic cracking, and isomerization- and alkylation reactions. This thesis deals with molecular aspects

  16. Redox Catalysis over Metallo-Zeolites. Contribution to Environmental Catalysis

    Czech Academy of Sciences Publication Activity Database

    Wichterlová, Blanka; Sobalík, Zdeněk; Dědeček, Jiří

    2003-01-01

    Roč. 41, - (2003), s. 97-114 ISSN 0926-3373 R&D Projects: GA AV ČR IBS4040016; GA AV ČR IAA4040007 Institutional research plan: CEZ:AV0Z4040901 Keywords : metallo-zeolites * Co-beta * Fe-ZSM-5 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.476, year: 2003

  17. Detergents–Zeolites and Enzymes Excel Cleaning Power

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 9; Issue 8. Detergents – Zeolites and Enzymes Excel Cleaning Power. B S Sekhon Manjeet K Sangha. General Article Volume 9 Issue 8 August 2004 pp 35-45. Fulltext. Click here to view fulltext PDF. Permanent link:

  18. Development of ZSM-5 Zeolite from Dealuminated Nigerian Ahoko ...

    African Journals Online (AJOL)

    The synthesis of ZSM-5 from dealuminated kaolin was a follow up to the earlier work on the synthesis of ZSM-5 zeolite from Nigerian Ahoko Kaolin in which external silica was added to make up for the Si/Al ratio requirement in MFI synthesis. In this work the dealumination of Ahoko metakaolin was carefully carried out to ...

  19. SYNTHESIS AND CHARACTERIZATION OF POLYIMIDE-ZEOLITE MIXED MATRIX MEMBRANE

    Directory of Open Access Journals (Sweden)

    Budiyono Budiyono

    2012-02-01

    Full Text Available Biogas has become an attractive alternative energy source due to the limitation of energy from fossil. In this study, a new type of mixed matrix membrane (MMM consisting of polyimide-zeolite was synthesized and characterized for biogas purification. The MMM consists of medium concentration of polymer (20% wt polyimide, 80% N-Methyl-2-pyrrolidone (NMP and 25% zeolite 4A in total solid were prepared by a dry/wet phase inversion technique.  The fabricated MMM was characterized using SEM, DSC, TGA and gas permeation. Post treatment coating procedure was also conducted. The research showed that surface coating by 3% silicone rubber toward MMM PI 20% gave the significant effect to improve membrane selectivity. The ideal selectivity for CO2/CH4 separation increased from 0.99 for before coating to 7.9 after coating for PI-Zeolite MMM, respectively. The results suggest that PI-Zeolite MMM with good post treatment procedure will increase the membrane selectivity and permeability with more saver polymer requirement as well as energy saving due to low energy for mixing.

  20. Microwave heating and the fast ADOR process for preparing zeolites

    Czech Academy of Sciences Publication Activity Database

    Navarro, M.; Morris, S. A.; Mayoral, A.; Čejka, Jiří; Morris, R. E.

    2017-01-01

    Roč. 5, č. 17 (2017), s. 8037-8043 ISSN 2050-7488 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : membranes * zeolites * microwave heating Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 8.867, year: 2016

  1. Silicalite-1 zeolite membranes on unmodified and modified surfaces

    Indian Academy of Sciences (India)

    Silicalite-1 zeolite membranes were prepared hydrothermally on the porous ceramic supports, both unmodified and modified with 3-aminopropyl triethoxysilane (APTES) as a coupling agent following ex situ (secondary) crystal growth process. The microstructure of the membranes was examined by scanning electron ...

  2. Simulation of Water Gas Shift Zeolite Membrane Reactor

    Science.gov (United States)

    Makertiharta, I. G. B. N.; Rizki, Z.; Zunita, Megawati; Dharmawijaya, P. T.

    2017-07-01

    The search of alternative energy sources keeps growing from time to time. Various alternatives have been introduced to reduce the use of fossil fuel, including hydrogen. Many pathways can be used to produce hydrogen. Among all of those, the Water Gas Shift (WGS) reaction is the most common pathway to produce high purity hydrogen. The WGS technique faces a downstream processing challenge due to the removal hydrogen from the product stream itself since it contains a mixture of hydrogen, carbon dioxide and also the excess reactants. An integrated process using zeolite membrane reactor has been introduced to improve the performance of the process by selectively separate the hydrogen whilst boosting the conversion. Furthermore, the zeolite membrane reactor can be further improved via optimizing the process condition. This paper discusses the simulation of Zeolite Membrane Water Gas Shift Reactor (ZMWGSR) with variation of process condition to achieve an optimum performance. The simulation can be simulated into two consecutive mechanisms, the reaction prior to the permeation of gases through the zeolite membrane. This paper is focused on the optimization of the process parameters (e.g. temperature, initial concentration) and also membrane properties (e.g. pore size) to achieve an optimum product specification (concentration, purity).

  3. zeolite catalysts for the selective synthesis of mono- and diethylamines

    NARCIS (Netherlands)

    Veefkind, V.A.; Lercher, J.A.

    1998-01-01

    The kinetics and mechanism of ethylamine synthesis from ammonia and ethanol over several large pore acid catalysts are described. Mordenite produced higher monoethylamine yields than the zeolites beta, Y, mazzite, and amorphous silica–alumina. The reaction proceeds via the initial formation of

  4. Two component permeation through thin zeolite MFI membranes

    NARCIS (Netherlands)

    Keizer, K.; Burggraaf, A.J.; Vroon, Z.A.E.P.; Verweij, H.

    1998-01-01

    Two component permeation measurements have been performed by the Wicke-Kallenbach method on a thin (3 μm) zeolite MFI (Silicalite-1) membrane with molecules of different kinetic diameters, d(k). The membrane was supported by a flat porous α-Al2O3 substrate. The results obtained could be classified

  5. Two-Dimensional Zeolites: Current Status and Perspectives

    Czech Academy of Sciences Publication Activity Database

    Roth, Wieslaw Jerzy; Nachtigall, P.; Morris, R. E.; Čejka, Jiří

    2014-01-01

    Roč. 114, č. 9 (2014), s. 4807-4837 ISSN 0009-2665 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : zeolites * mesoporous molecular sieves * Fischer-Tropsch synthesis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 46.568, year: 2014

  6. Hydrodesulfurization over PdMo/HY zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pawelec, B.; Navarro, R.; Fierro, J.L.G.; Cambra, J.F.; Zugazaga, F.; Guemez, M.B.; Arias, P.L. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain)

    1997-01-01

    A series of palladium-promoted Mo catalysts was prepared by a two-step impregnation procedure using an ultrastable HY zeolite carrier. The mutual effect of Pd and Mo phases and zeolitic support was investigated in hydrodesulfurization (HDS) of dibenzothiophene (DBT) and diesel oil (1.1. wt% S), Pd/HY was more active than its binary PdMo/HY counterparts, suggesting an inhibitory effect of Mo on Pd. The incorporation of Pd probably prevented deactivation of PdMo catalysts in HDS of DBT. The initial sulfur conversion in HDS of gas oil over Pd/HY was similar to that on a commercial CoMo/Al{sub 2}O{sub 3} catalysts; however, both Pd/HY catalyst and the blank HY zeolite deactivated very fast at short times on-stream. On the basis of catalyst characterization by X-ray photoelectron spectroscopy, Fourier transform i.r. spectroscopy of adsorbed CO and pyridine, and temperature-programmed reduction, it is concluded that formation of hydride-like species in PdMo zeolites are probably responsible for the inhibitory effect on HDS activity. 38 refs., 8 figs., 3 tabs.

  7. Hydrocracking activity of NiMo-USY zeolite hydrotreating catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Egia, B.; Cambra, J.F.; Gueemez, B.; Arias, P.L. [Departamento de Ingeniera Quimica y del Medio Ambiente. Escuela de Ingenieros, Bilbao (Spain); Pawelec, B.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain)

    1997-07-01

    In previous works the hydrodesulfurization and hydrodenitrogenation activities of Ni, Mo and MoNi zeolite supported catalysts were studied, and a remarkable initial deactivation by cocking was detected. In the present work the hydrocracking activity of these catalysts in the sulfided state has been studied. 21 refs.

  8. Detergents – Zeolites and Enzymes Excel Cleaning Power

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 9; Issue 8. Detergents – Zeolites and Enzymes Excel Cleaning Power. B S Sekhon Manjeet K Sangha. General Article Volume 9 Issue 8 August 2004 pp 35-45. Fulltext. Click here to view fulltext PDF. Permanent link:

  9. Preparation of High Grade Silica from Rice Husk for Zeolite ...

    African Journals Online (AJOL)

    ABSTRACT: Silica powder with approximately 96% purity was extracted from rice husk (RH) and used as a silica source for the synthesis of zeolite Y by hydrothermal process. The effect of synthesis parameters such as pH, temperature of burning the rice husk, acid leaching prior to formation of rice husk ash (RHA) on the ...

  10. Vanadia supported on zeolites for SCR of NO by ammonia

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Riisager, Anders; Fehrmann, Rasmus

    2010-01-01

    , acidity and micropore structure of the support. Apparently the support hosted the potassium oxide on the acid sites, thereby protecting the active vanadium species from poisoning. Zeolite based catalysts might therefore prove useful for SCR of NO in alkali-containing flue gases from, e.g. biomass fired...

  11. Pore Topology Effects in Positron Annihilation Spectroscopy of Zeolites.

    Science.gov (United States)

    Zubiaga, Asier; Warringham, Robbie; Mitchell, Sharon; Gerchow, Lars; Cooke, David; Crivelli, Paolo; Pérez-Ramírez, Javier

    2017-03-03

    Positron annihilation spectroscopy (PAS) is a powerful method to study the size and connectivity of pores in zeolites. The lifetime of positronium within the host material is commonly described by the Tao-Eldrup model. However, one of its largest limitations arises from the simple geometries considered for the shape of the pores, which cannot describe accurately the complex topologies in zeolites. Here, an atomic model that combines the Tao potential with the crystallographic structure is introduced to calculate the distribution and lifetime of Ps intrinsic to a given framework. A parametrization of the model is undertaken for a set of widely applied zeolite framework types (*BEA, FAU, FER, MFI, MOR, UTL), before extending the model to all known structures. The results are compared to structural and topological descriptors, and to the Tao-Eldrup model adapted for zeolites, demonstrating the intricate dependence of the lifetime on the pore architecture. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Zeolit Sintetis Terfungsionalisasi 3-(Trimetoksisilil-1-Propantiol sebagai Adsorben Kation Cu(II dan Biru Metilena

    Directory of Open Access Journals (Sweden)

    Sri Sugiarti

    2017-05-01

    Full Text Available The more commonly used method for making synthetic zeolite from kaolin is hydrothermal method. This research tested a sol-gel method in processing synthetic zeolit  using kaolin as the basic ingrediant. The synthetic  zeolite  derived from the sol-gel method was then characterized using X-ray Difractometer and Scanning Electron Microscope, which found resulting products zeolite-A, zeolite Y and sodalite. The adsorption ability of the synthetic zeolites was tested using Cu(II and methylene blue.  Functionalization of the synthetic zeolites by 3-(trimetoksisilil-1-propantiol was  done to increase adsorption capacity. Zeolite A modified by 3-(trimetoksisilil-1-propantiol  had the greater capacity to adsorb methylene blue at 30.11 mg/g. The adsorption isotherms of all the synthetic zeolites approached the Langmuir form. The adsorption energy off all synthetic zeolites approached the chemical adsorption.DOI: http://dx.doi.org/10.15408/jkv.v0i0.5144

  13. Possibility of Modification of Zeolites by Iron Oxides and its Utilization for Removal of Pb(II from Water Solutions

    Directory of Open Access Journals (Sweden)

    Michal Lovás

    2004-12-01

    Full Text Available Ion-exchange properties of cations from lattice and ions from solutions are characteristic for zeolites. Zeolites as sorbents are used in many branches of industry. Ion-exchange reactions of cations on zeolites have been a theme of many works. With the exception of using natural zeolites as the sorbent, a modification of surface of zeolites and preparation of synthetic zeolites has received interest lately. One of the common modification of zeolites is modification by iron oxides, which increases capacity of adsorption. In this work, we prepared a modified zeolite by the precipitation of magnetite on the surface of zeolite. This new adsorbent was used to remove of Pb(II from waste water. The maximum adsorption capacity was 73,25 mg/g from the solution of Pb with the concentration of 400 mg/l.

  14. The role of the zeolite channel architecture and acidity on the activity and selectivity in aromatic transformations: The effect of zeolite cages in SSZ-35 zeolite

    Czech Academy of Sciences Publication Activity Database

    Žilková, Naděžda; Voláková, Martina; Gil, B.; Zones, S. I.; Burton, A. W.; Chen, C.-Y.; Musilová, Zuzana; Košová, Gabriela; Čejka, Jiří

    2009-01-01

    Roč. 266, č. 1 (2009), s. 79-91 ISSN 0021-9517 R&D Projects: GA AV ČR 1QS400400560; GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40400503 Keywords : zeolite architecture * cage effect * acidity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.288, year: 2009

  15. Adsorption of nicotine on different zeolite types, from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Stošić Dušan K.

    2007-01-01

    Full Text Available The plant alkaloid, nicotine, is a strongly toxic heterocyclic compound: the lethal dose for an adult human being (40-60 mg is importantly lower in comparison with the other known poisons such as arsenic or strychni­ne. Cigarettes represent "the most toxic and addictive form of nicotine". Besides the negative effects of nicotine on public health produced by self-administration, recently another potentially very dangerous effect has been recognized: because of its miscibility with water, nicotine can be found in industrial wastewaters, and consequently, in groundwater. Therefore, the problem of nicotine removal from aqueous solutions has became an interesting topic. In this work, the removal of nicotine has been probed by adsorption on solid materials. Adsorption of nicotine on different zeolites (clinoptilolite, ZSM-5 and β zeolite and on activated carbon was investigated from aqueous solutions, at 298 K. The obtained results are presented as adsorption isotherms: the amount of adsorbed nicotine as a function of equilibrium concentration. These data were obtained from the residual amount of nicotine in the aqueous phase, by the use of UV spectroscopy. The highest amounts of adsorbed nicotine was found for activated carbon and p zeolite (~ mmol·g-1. The attempt to modify the adsorption properties of ZSM-5 zeolite has been also done: ZSM-5 was modified by ion-exchange with VIII group metal (Cu2+ and Fe3+. In addition, the adsorption of nicotine on ZSM-5 zeolite with different Si/Al ratios has been done. It has been noticed that ion-exchange did not improve the adsorption possibilities, while the adsorption was importantly lower in the case of higher silicon content in ZMS-5 structure. 13C NMR spectra were collected for suspensions formed of solid adsorbent and aqueous solution of nicotine; in this way, the part of nicotine molecule which is most probably connected with the adsorbent was recognized.

  16. Synthesis of highly effective adsorbents from natural raw materials (zeolites)

    International Nuclear Information System (INIS)

    Shopova, N.; Schwieger, W.; Makraduli, M.

    1996-01-01

    Natural raw materials bentonite, silica tuff and diatomaceous earth from Macedonia were used in synthesis of zeolites type A, ZSM-5 and multilayer silicate magadiite-adsorbents. The bentonite was subject to pretreatment with acids (HCl and H 2 SO 4 - 5, 10, 15 and W%) or NaOH, and used in synthesis of zeolite type A having molar ratio of: 2Na 2 O : Al 2 O 3 : 2SiO 2 : 100H 2 O. Silicate tuff was applied (without any pretreatment, in a two stage reaction) in a high temperature synthesis, using butylamine as an organic 'template' component in order to get high silica zeolite type ZSM-5 having molar ratio of: 59.37SiO 2 : Al 2 O 3 : 3.84Na 2 O : 1.90R 2 O : 2025.10H 2 O. Multilayer silicate magadiite MS-H was synthesized from natural raw material diatomaceous earth. The product with a molar ratio of: 8SiO 2 : Na 2 O : 75H 2 O showed the best characteristics. The proposed method of alkaline pretreatment is a new one and it is acceptable from the economy point of view due to low energy consumption. The conclusion shows that the final result of the synthesis was not perfect, i.e. it has 70% of zeolite ZSM-5 and the rest were some amorphous phases. This product is suitable for industrial application in catalytic processes due to the fact that commercial catalyst contain typically 20 to 50% of zeolite type ZSM-5. On the other hand, the magadiite being multilayer silicate with no aluminium inside, is well suited as a carrier due to its ability of intercalation. The experimental results indicate that natural raw materials from Macedonia could be used for synthesis of synthetical silicates with high qualities and acceptable overall costs, specially when alkaline pretreatment is used. 14 refs., 4 tabs., 11 figs

  17. FTIR Study of Metal Zeolites. Determination of Co(II) Cation in Co-BETA Zeolite by Deuterated Acetonitrile Adsorption

    Czech Academy of Sciences Publication Activity Database

    Kuriyavar, S.; Bortnovsky, Oleg; Tvarůžková, Zdenka; Sobalík, Zdeněk

    2001-01-01

    Roč. 66, č. 4 (2001), s. 685-692 ISSN 0010-0765 R&D Projects: GA AV ČR IBS4040016 Institutional research plan: CEZ:AV0Z4040901 Keywords : deuterated acetonitrile * cobalt * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.778, year: 2001

  18. Synthesis of a hierarchically structured zeolite-templated carbon starting from fly ash-derived zeolite X

    CSIR Research Space (South Africa)

    Musyoka, Nicholas M

    2014-05-01

    Full Text Available the need for the use of structure directing template as well as from a waste material. Therefore the process of synthesizing hierachical carbon replicas starting from fly-ash derived zeolites presents a cost-effective alternative for producing carbonaceous...

  19. Acid-catalyzed Synthesis of Mono and Diakyl Benzenes over Zeolites. Active Sites, Zeolite Topology, and Reaction Mechanisms

    Czech Academy of Sciences Publication Activity Database

    Čejka, Jiří; Wichterlová, Blanka

    2002-01-01

    Roč. 44, - (2002), s. 375-422 ISSN 0161-4940 R&D Projects: GA AV ČR IAA4040001; GA AV ČR IAA4040707 Institutional research plan: CEZ:AV0Z4040901 Keywords : alkyl aromatic * zeolites * molecular sieves Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.455, year: 2002

  20. The Effect of Zeolite Composition and Grain Size on Gas Sensing Properties of SnO2/Zeolite Sensor

    Directory of Open Access Journals (Sweden)

    Yanhui Sun

    2018-01-01

    Full Text Available In order to improve the sensing properties of tin dioxide gas sensor, four kinds of different SiO2/Al2O3 ratio, different particle size of MFI type zeolites (ZSM-5 were coated on the SnO2 to prepared zeolite modified gas sensors, and the gas sensing properties were tested. The measurement results showed that the response values of ZSM-5 zeolite (SiO2/Al2O3 = 70, grain size 300 nm coated SnO2 gas sensors to formaldehyde vapor were increased, and the response to acetone decreased compared with that of SnO2 gas sensor, indicating an improved selectivity property. The other three ZSM-5 zeolites with SiO2/Al2O3 70, 150 and 470, respectively, and grain sizes all around 1 μm coated SnO2 sensors did not show much difference with SnO2 sensor for the response properties to both formaldehyde and acetone. The sensing mechanism of ZSM-5 modified sensors was briefly analyzed.

  1. Bagging constrained equity premium predictors

    DEFF Research Database (Denmark)

    Hillebrand, Eric; Lee, Tae-Hwy; Medeiros, Marcelo

    2014-01-01

    The literature on excess return prediction has considered a wide array of estimation schemes, among them unrestricted and restricted regression coefficients. We consider bootstrap aggregation (bagging) to smooth parameter restrictions. Two types of restrictions are considered: positivity of the r......The literature on excess return prediction has considered a wide array of estimation schemes, among them unrestricted and restricted regression coefficients. We consider bootstrap aggregation (bagging) to smooth parameter restrictions. Two types of restrictions are considered: positivity...... of the regression coefficient and positivity of the forecast. Bagging constrained estimators can have smaller asymptotic mean-squared prediction errors than forecasts from a restricted model without bagging. Monte Carlo simulations show that forecast gains can be achieved in realistic sample sizes for the stock...... return problem. In an empirical application using the data set of Campbell and Thompson (2008), we show that we can improve the forecast performance further by smoothing the restriction through bagging....

  2. The study on effect of zeolite on nitrogen use efficiency of corn by 15N-isotope dilution method

    International Nuclear Information System (INIS)

    Li Changhong; Li Huaxing; Zhang Xinming; Liu Yuanjin

    2002-01-01

    A pot experiment was carried out to study the effect of natural zeolite on nitrogen use efficiency of corn by using 15 N-isotope dilution method. The results showed that application of zeolite could improve the corn growth and enhance the biomass of the corn seedling. By using zeolite, nitrogen use efficiency (NUE) of corn was increased by 23.2%-33.1% as compared with no-zeolite treatment; and the residual nitrogen has no significant difference between zeolite treatment and no-zeolite treatment

  3. Linde Type A and nano magnetite/NaA zeolites: cytotoxicity and doxorubicin loading efficiency

    Directory of Open Access Journals (Sweden)

    Divband B.

    2018-02-01

    Full Text Available Different cation-exchanged (K+, Na+ & Ca2+ nano-zeolites withi magnetite nanocomposites were synthesized and their suitability for drug loading was studied. Nanocomposites with different Fe3O4 contents were synthesized by adding magnetic Fe3O4 nanoparticles to the zeolite crystallization solution. The zeolite and its nanocomposites had high surface areas and enough adsorption capacity to load and release sufficient amounts of the chemotherapeutic doxorubicin. None or the zeolites or nanocomposites showed toxicity to SKBr3 or MCF-7 cancer cells. However, DOX@zeolite inhibits cell growth more than the non-encapsulated drug. Thus zeolites and their magnetite nanocomposites show potential as biocompatible medical devices.

  4. Dispersible Exfoliated Zeolite Nanosheets and Their Application as a Selective Membrane

    Science.gov (United States)

    Varoon, Kumar; Zhang, Xueyi; Elyassi, Bahman; Brewer, Damien D.; Gettel, Melissa; Kumar, Sandeep; Lee, J. Alex; Maheshwari, Sudeep; Mittal, Anudha; Sung, Chun-Yi; Cococcioni, Matteo; Francis, Lorraine F.; McCormick, Alon V.; Mkhoyan, K. Andre; Tsapatsis, Michael

    2011-10-01

    Thin zeolite films are attractive for a wide range of applications, including molecular sieve membranes, catalytic membrane reactors, permeation barriers, and low-dielectric-constant materials. Synthesis of thin zeolite films using high-aspect-ratio zeolite nanosheets is desirable because of the packing and processing advantages of the nanosheets over isotropic zeolite nanoparticles. Attempts to obtain a dispersed suspension of zeolite nanosheets via exfoliation of their lamellar precursors have been hampered because of their structure deterioration and morphological damage (fragmentation, curling, and aggregation). We demonstrated the synthesis and structure determination of highly crystalline nanosheets of zeolite frameworks MWW and MFI. The purity and morphological integrity of these nanosheets allow them to pack well on porous supports, facilitating the fabrication of molecular sieve membranes.

  5. The Usage of Natural Zeolites for the Adsorption of Radionuclides, particularly in emergency situations

    International Nuclear Information System (INIS)

    Reitbauer, Franz

    2012-09-01

    Specific natural zeolites have proven their capability to bind nuclear radiation During the last decades, numerous research work has proven the potential of natural zeolites to adsorb nuclear radiation through their cation exchange properties. Zeolites have been used successfully in Chernobyl, and are used in Fukushima and in nuclear waste repositories today. Within the various kinds of zeolites the special type clinoptilolite particularly binds 137-cesium as well as 90- strontium ions. Therefore zeolites with high contents of clinoptilolite are the first choice for this purpose. High contents of clinoptilolite can be defined as being above 90 %. Such zeolites are typically capable of binding some 2,50 meq/g of cesium ions and some 1,40 meq/g of strontium ions. (authors)

  6. Palm oil mill effluent treatment: Influence of zeolite, municipal wastewater and combined aerobic SBR system

    Science.gov (United States)

    Farraji, Hossein; Zaman, Nastaein Qamaruz; Aziz, Hamidi Abdul; Sa'at, Siti Kamariah Md

    2017-10-01

    Anaerobically treated palm oil mill effluent (POME) used as an infant in the aerobic sequencing batch reactor (SBR). Three different treatments such as 15 g/L zeolite, municipal wastewater (MWW) and combining zeolite and municipal wastewater in comparing with the only aeration used in a lab scale batch study. Spectrophotometric analysis carried out for chemical oxygen demand (COD), ammonia nitrogen, total suspended solids, colour and total phosphorus as target characteristics of raw and treated POME. Zeolite and MWW augmented SBR contain POME + zeolite + MWW had significantly more performance compared with POME (blank) in all analyzed target factors. The results of this study indicate that MWW has significantly higher influence in decontamination of POME in comparing with zeolite. Combining zeolite and MWW in aerobic SBR could meet Malaysian environmental discharge for POME in 22 hours.

  7. Obtaining of supports macro and micro nutrients with base in zeolites mexicans

    International Nuclear Information System (INIS)

    Cordova H, A.; Islas M, M.; Bascunan S, C.; Martines G, M.; Nikolaev N, S.

    2001-01-01

    Study the effect of application of the zeolites modified by the ionico interchange with fertilizers (NPK), N-p in the production of tomatos. The cultive of tomatos was made in lands of the Benemerita Autonoma Universidad de Puebla, Mexico, taking equal quadrants with the following ground treatments: 1) zeolite interchanged with fertilizers, 2) zeolite interchanged with a solution that contained only N-p, 3) natural zeolite without ionica modification and a quadrant witness represented by the ground without treatment. The collected data show an increase in the harvest of tomatos, as well as the retention of the decomposition of the harvested tomatos. In addition, it determinated that the optimal concentrations in the case of the zeolite dealt with 3% of fertilizer NPK are: 0,91% of potassium and 0.61% of nitrogen. These results allow to suggest the use of zeolites modified by ionico interchange in agriculture to elevate the level of the harvests of the tomato [es

  8. Environmental applications of natural zeolitic materials based on their ion-exchange properties

    International Nuclear Information System (INIS)

    Colella, C.

    1998-01-01

    Natural zeolites, such as clinoptilolite, chabazite, phillipsite and mordenite, exhibit good selectivities for some water pollutants, e.g., Cs + , NH 4 + and Pb 2+ . Zeolite-rich tuffs may be therefore utilized for removing the above and other cations from wastewaters before discharge. Continuous processes with fixed beds are usually employed for water purification, such as those in service in the U.S.A for ammonium removal from municipal sewage. Direct action of the ion exchanger is needed when the pollutant must be removed from soil and trapped in the zeolite framework. Discontinuous processes (addition of zeolite to the waste solution) are also possible, provided the polluted zeolitic sludge is stabilized-solidified in a cement matrix matrix before disposal. Removal of radionuclides from nuclear power plant waters with natural zeolites is discussed

  9. Characterization of natural and modified zeolites using ion beam analysis techniques

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, E. [Instituto de Fisica, Departamento de Fisica Experimental, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 (Mexico)], E-mail: andrade@fisica.unam.mx; Solis, C. [Instituto de Fisica, Departamento de Fisica Experimental, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 (Mexico); Aceves, J.M.; Miranda, R. [Facultad de Estudios Superiores Cuautitlan Itzcalli, Departamento de Quimica, Universidad Nacional Autonoma de Mexico, 1 de Mayo S/N, Cuatitlan Itzcalli, Edo. de Mexico, C.P. 74540 (Mexico); Cruz, J. [Instituto de Fisica, Departamento de Fisica Experimental, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 (Mexico); Rocha, M.F. [Escuela Superior de Ingenieria Mecanica y Electrica, Instituto Politecnico Nacional, U.P. ' Adolfo Lopez Mateos' , Zacatenco, Del. Gustavo A. Madero, Mexico D.F. 07738 (Mexico); Zavala, E.P. [Instituto de Fisica, Departamento de Fisica Experimental, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 (Mexico)

    2008-05-15

    Zeolites are very important materials in catalytic and industrial processes. Natural, modified and synthetic zeolites have a wide range of uses because of their good adsorption, ion exchange capacity and catalytic properties. Mexico is an import source of natural zeolites, however their utilization in the natural form is limited due to the presence of trace metallic impurities. For example, metals such as vanadium and chromium inhibit the elimination of sulfur in hydrocarbons. Therefore, it is important to know the precise composition of the zeolite material. In this work, we report the elemental characterization of zeolites using various IBA techniques. {sup 3}He{sup +} and {sup 2}H{sup +} beams were used to measure the major element concentrations (Si, Al, O, C) by RBS and NRA. PIXE and SEM-EDS were used to measure the total trace element content (V, Cr, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Pb, etc). Additionally, XRD was used to study the zeolite crystal structure.

  10. Quantization in curved space

    International Nuclear Information System (INIS)

    Oliveira, N.T. de; Lobo, R.

    1980-01-01

    The quantization of systems moving in Riemannian manifold is performed by first embeding the space into a larger Euclidean space. The reduction to the original manifold is performed using Dirac's treatment of degenerate Lagrangean and Faddeev-Fradkin quantization technique for constrained Hamiltonian systems. (L.C.) [pt

  11. Studies of zeolite-based artificial photosynthetic systems

    Science.gov (United States)

    Zhang, Haoyu

    Two ruthenium polypyridyl compounds of structural formula [(bpy) 2RuL]2+ (RuL) and [(bpy)2RuLDQ]4+ (RuLDQ) (where bpy = bipyridine, L = trans-1,2-bis-4-(4'-methyl)-2,2'-bipyridyl) ethane, LDQ = 1-[4-(4'-methyl)-2,2'-bipyridyl)]-2-[4-(4'-N,N'-tetramethylene-2,2'-bipyridinium)] ethene) were synthesized and purified. From pH titrations, it was found that the Ru complex was a stronger base (pKa* = 6) in the excited state than in the ground state (pKa = 4). Photolysis of the RuL complex in solutions at pH 7 and 12 led to formation of species with increased emission quantum yields, ˜55 nm blue-shift of the emission maximum to 625 nm and disappearance of the absorption band at 330 nm, the latter arising from the olefinic bond of the L ligand. Photoproducts formed at neutral pH have been analyzed. It was found that the major product was a dimer of RuL, dimerizing around the double bond. Photoreactions did not occur in the dark or in the aprotic solvent acetonitrile. We proposed that a Ru(III) radical intermediate was formed by photoinduced excited-state electron and proton transfer, which initiated the dimerization. The radical intermediate also underwent photochemical degradative reductions. Below pH 4, the emission quenching was proposed to arise via protonation of the monoprotonated RuLH + followed by electron transfer to the viologen-type moiety created by protonation. The products of photodegradation at pH > 12 were different from those of pH 7, but the mechanism of the degradation at pH > 12 was not elucidated. RuLDQ was stable under visible irradiation. We examined nanocrystalline zeolite as a host for light absorbing sensitizers (electron donors) and electron acceptors. Nanocrystalline zeolite Y (NanoY) with uniform particle size, pure phase was prepared. NanoY was obtained by periodically removing nanocrystals from the mother liquor and recycling the unused reagents. The nanoparicles were characterized by XRD and TEM. Optically clear colloidal solutions of Nano

  12. Zeolite Membranes in Catalysis—From Separate Units to Particle Coatings

    OpenAIRE

    Radostina Dragomirova; Sebastian Wohlrab

    2015-01-01

    Literature on zeolite membranes in catalytic reactions is reviewed and categorized according to membrane location. From this perspective, the classification is as follows: (i) membranes spatially decoupled from the reaction zone; (ii) packed bed membrane reactors; (iii) catalytic membrane reactors and (iv) zeolite capsuled catalyst particles. Each of the resulting four chapters is subdivided by the kind of reactions performed. Over the whole sum of references, the advantage of zeolite membran...

  13. Tailoring ZSM-5 Zeolites for the Fast Pyrolysis of Biomass to Aromatic Hydrocarbons

    DEFF Research Database (Denmark)

    Hoff, Thomas C.; Gardner, David W.; Thilakaratne, Rajeeva

    2016-01-01

    The production of aromatic hydrocarbons from cellulose by zeolite-catalyzed fast pyrolysis involves a complex reaction network sensitive to the zeolite structure, crystallinity, elemental composition, porosity, and acidity. The interplay of these parameters under the reaction conditions represents...... a major roadblock that has hampered significant improvement in catalyst design for over a decade. Here, we studied commercial and laboratory-synthesized ZSM-5 zeolites and combined data from 10 complementary characterization techniques in an attempt to identify parameters common to high...

  14. Aluminum sulphate production and zeolite from residual muds of the company Extralum S.A

    International Nuclear Information System (INIS)

    Carranza, C.; Montero, M.

    2002-01-01

    As part of our research on alternative raw materials for the chemical industry we studied sludge from an anodizing process at Extralum S.A. The sludge contains mainly bayerite, Al(OH) 3 and bohemite A1O (OH). Starting from these we developed a hydrothermal synthesis of Aluminium sulphate and Zeolite A. The Zeolite A was identified by Powder X-ray crystallography. The scanning electron microscope image of the Zeolite A shows a very high degree of crystallinity. (Author) [es

  15. Effects of reactive filters based on modified zeolite in dairy industry wastewater treatment process

    OpenAIRE

    Kolaković, Srđan; Stefanović, Dragoslav; Milićević, Dragan; Trajković, Slaviša; Milenković, Slobodan; Kolaković, Slobodan S.; Anđelković, Ljiljana

    2013-01-01

    Application of adsorbents based on organo-zeolites has certain advantages over conventional methods applied in food industry wastewater treatment process. The case study presented in this paper examines the possibilities and effects of treatment of dairy industry wastewater by using adsorbents based on organo-zeolites. The obtained results indicate favorable filtration properties of organo-zeolite, their high level of adsorption of organic matter and nitrat...

  16. The potential of Saudi Arabian natural zeolites in energy recovery technologies

    International Nuclear Information System (INIS)

    Nizami, A.S.; Ouda, O.K.M.; Rehan, M.; El-Maghraby, A.M.O.; Gardy, J.; Hassanpour, A.; Kumar, S.; Ismail, I.M.I.

    2016-01-01

    Energy consumption in KSA (kingdom of Saudi Arabia) is growing rapidly due to economic development with raised levels of population, urbanization and living standards. Fossil fuels are currently solely used to meet the energy requirements. The KSA government have planned to double its energy generating capacity (upto 120 GW (gigawatts)) by 2032. About half of the electricity capacity of this targeted energy will come from renewable resources such as nuclear, wind, solar, WTE (waste-to-energy) etc. Natural zeolites are found abundantly in KSA at Jabal Shamah occurrence near Jeddah city, whose characteristics have never been investigated in energy related applications. This research aims to study the physical and chemical characteristics of natural zeolite in KSA and to review its potential utilization in selected WTE technologies and solar energy. The standard zeolite group of alumina–silicate minerals were found with the presence of other elements such as Na, Mg and K etc. A highly crystalline structure and thermal stability of natural zeolites together with unique ion exchange, adsorption properties, high surface area and porosity make them suitable in energy applications such as WTE and solar energy as an additive or catalyst. A simple solid–gas absorption system for storing solar energy in natural zeolites will be a cheap alternative method for KSA. In AD (anaerobic digestion), the dual characteristics of natural zeolite like Mordenite will increase the CH 4 production of OFMSW (organic fraction of municipal solid waste). Further investigations are recommended to study the technical, economical, and environmental feasibility of natural zeolite utilization in WTE technologies in KSA. - Highlights: • A highly crystalline structure is found in natural zeolites. • Natural zeolites will store solar energy in solid–gas absorption system. • The composites of natural zeolites will produce more liquid fuel like gasoline. • The natural zeolite will increase

  17. Alkali-activated blast furnace slag-zeolite cements and concretes

    International Nuclear Information System (INIS)

    Rakhimov, R.; Rakhimova, N.

    2012-01-01

    The aim of this work has been the study of alkali-activated slag-zeolite cements and concretes based on them. Various compositions have been tested and some characteristics such as the compressive strength have been measured versus zeolite additions. A table lists the specific surface area and particle size distributions of different cements. The conclusions of the study are the following. First, alkali-activated slag cements and concretes based on them are effective for immobilization of radioactive wastes and the production of building structures, designed for high radiation load. Secondly, zeolite-containing mineral additions are able to increase the immobilization capacity and radiation resistance of alkali-activated blast furnace slag cements and concretes. Thirdly, the efficiency of different zeolite-containing additions - 10% to increase alkali-activated blast furnace slag-zeolite cement strength was established. It is with alkaline components of water-glass, sodium carbonate, sodium sulphate. Fourth, the effective way of introducing zeolite additions in alkali-activated blast furnace slag-zeolite cement is inter-grinding of the slag and addition. Increase in strength of alkali-activated blast furnace slag-zeolite cement stone is 40% higher than that of the stone of a mixture of separately milled components. Fifth, Alkali-activated blast furnace slag-zeolite cements with zeolite-containing additions with a compressive strength of 10.1 to 140 MPa; alkali-activated blast furnace slag-zeolite cements mortars with compressive strength from 35.2 to 97.7 MPa; alkali-activated blast furnace slag-zeolite cements concretes with compressive strength up to 84.5 MPa and frost resistant up to 800 cycles were obtained

  18. Isobutane/2-butene alkylation with zeolite Y without BrÆnsted acidity

    OpenAIRE

    Rosenbach Jr,Nilton; Mota,Claudio J. A.

    2005-01-01

    Alkylation of isobutane with 2-butene was performed on metal-exchanged Y zeolites, using an alkylchloride as carbocation initiator. The results indicated that, compared with a protonic zeolite, the deactivation was significantly slower and the production of trimethylpentanes was higher on the metal-exchanged zeolites. The metal cations act as Lewis acids, interacting with the chloride initiating the carbocationic reactions. The results also support the view that protonic sites on the catalyst...

  19. Treatment of effluent containing uranium with magnetic zeolite

    International Nuclear Information System (INIS)

    Craesmeyer, Gabriel Ramos

    2013-01-01

    Within this work, a magnetic-zeolite composite was successfully synthesized using ferrous sulfate as raw material for the magnetic part of the composite, magnetite, and coal fly ash as raw material for the zeolitic phase. The synthesis of the zeolitic phase was made by alkali hydrothermal treatment and the magnetite nanoparticles were obtained through Fe 2+ precipitation on alkali medium. The synthetic process was repeated many times and showed good reproducibility comparing the zeolitic nanocomposite from different batches. The final product was characterized using infrared spectroscopy, powder X-ray diffraction, X-ray fluorescence, scanning electron microscopy with coupled EDS. Specific mass, specific surface area and other physicochemical proprieties. The main crystalline phases found in the final product were magnetite, zeolites types NaP1 and hydroxysodalite, quartz and mullite, those last two remaining from the raw materials. Uranium removal capacity of the magnetic zeolite composite was tested using batch techniques. The effects of contact time and initial concentration of the adsorbate over the adsorption process were evaluated. Equilibrium time was resolved and the following kinetics and diffusion models were evaluated: pseudo-first order kinetic model, pseudo-second order kinetic model and interparticle diffusion model. A contact time of 120 min turned out to be enough to reach equilibrium of the adsorption process. The rate of adsorption followed the pseudo-second order model and the intra particle diffusion did not turn out to be a speed determinant step. Two adsorption isotherms models, the Langmuir model and the Freundlich model, were also evaluated. The Langmuir model was the best fit for the obtained experimental data. Using the best fitted adsorption isotherm and kinetic model, the theoretical maximum adsorption capacity of uranium over the composite was determined for both models. The maximum removal capacity calculated was 20.7 mg.g -1 for the

  20. Immobilization of krypton-85 in zeolite 5A

    International Nuclear Information System (INIS)

    Christensen, A.B.; Del Debbio, J.A.; Knecht, D.A.; Tanner, J.E.; Cossel, S.C.

    1983-01-01

    This paper describes the technical feasibility and presents a summary of a preconceptual design and cost estimate for a process to immobilize krypton-85 by sintering in zeolite 5A at 700 0 C and 100 MPa for 2 to 4 h. Krypton loading of 30 to 60 m 3 at STP per m 3 solid can be achieved. The initial water concentration in zeolite 5A has a catalytic effect on the sintering rate and must be kept at about 1 wt% by heating prior to the encapsulation run. High initial water loadings and/or encapsulation times longer than 4 h must be avoided because the sintered zeolite 5A recrystallizes to an anorthite-type feldspar and releases the trapped krypton. Data are presented to show how the process conditions affect krypton encapsulation in zeolie 5A and how to assure the quality of the product. By adding a powdered glass frit to the commercial zeolite 5A 2 mm beads, a solid mass is formed during encapsulation, which can be further compacted using standard hot isotatic pressing techniques at 33 MPa and 600 0 C to form a fused glassy matrix enclosing the amorphous zeolite. A process for encapsulating the annual krypton-85 production at a commercial 2000 metric ton of heavy metal spent fuel reprocessing plant is developed. A hot isostatic press (HIP) with an isolated work zone of 8 or 16 L capacity is required to operate for 600 or 300 cycles per year, respectively. Existing HIP technology uses work zones from 1 to 3500 L capacity at similar production rates. A combined encapsulation/compaction cycle is proposed as an option to most effectively immobilize the krypton and the zeolite. A preconceptual design and cost estimate is given for a commercial-scale Kr encapsulation facility. The facility is designed to withstand a worst case rupture of the HIP. The maximum lease is estimated to result in an off-site dose well below accident protective action guidance levels

  1. Effect of the framework structure on the dealumination-realumination behavior of zeolite

    International Nuclear Information System (INIS)

    Oumi, Y.; Nemoto, S.; Nawata, S.; Fukushima, T.; Teranishi, T.; Sano, T.

    2003-01-01

    The dealumination-realumination processes of MOR, MFI, FER and BEA zeolites were investigated by means of XRD, 27 Al MAS NMR, FT-IR and N 2 adsorption. Framework aluminums of BEA zeolite were easily removed from the framework by HCl treatment. Dealumination of MOR zeolite was performed by a combination of calcination in air and HCl treatment. However, in the case of MFI and FER zeolites, although the aluminums were taken out of their frameworks by calcination, they remained in the zeolites even after subsequent HCl treatment. This indicates that the structure type is one of the major factors that influence the dealumination behavior. From realumination of various dealuminated zeolites by pH control in solution, it was also found that aluminum species in the solution, which are eliminated from the frameworks of BEA and MOR zeolites by HCl treatment, are easily reinserted into the frameworks by controlling the pH value of the suspension below 7. The amount of incorporated aluminums increased with an increase in the pH value. However, in the case of MOR zeolite, all of incorporated aluminums were not necessarily responsible for generation of tetrahedral coordinated sites. Reinsertion of non-framework aluminums into the dealuminated MFI and FER zeolites hardly occurred

  2. Langmuir and Freundlich Isotherm Adsorption Equations for Chromium (VI) Waste Adsorption by Zeolite

    International Nuclear Information System (INIS)

    Murni Handayani; Eko Sulistiyono

    2009-01-01

    The research of chromium (VI) waste adsorption by zeolite has done. Wastes which are produced by Industries, both radioactive waste and heavy metal waste need done more processing so that they are not endanger environment and human health. Zeolite has very well-ordered crystal form with cavity each other to way entirely so that cause surface wide of zeolite become very big and very good as adsorbents. This research intends to know appropriate isotherm adsorption method to determine maximum capacity of zeolite to chromium (VI) waste. The equations which used in adsorption process are Langmuir and Freundlich isotherm Adsorption equations. The instrument was used in adsorption process by using Atomic Adsorption Spectroscopy (AAS). The experiment result showed that the biggest mass of chromium (VI) metal ion which was absorb by zeolite in 20 ppm concentration was 7.71 mg/gram zeolite. Adsorption process of Chromium (VI) waste by zeolite followed Langmuir and Freundlich isotherm equations with R 2 >0,9 . Appropriate equation to determine maximum adsorption capacity of zeolite for chromium (VI) waste adsorption is Langmuir equation. The maximum adsorption capacity of zeolite is 52.25 mg/gram. (author)

  3. The Separation and the Concentration of Minerals from the Zeolitic Volcanic Tuffs. Analytical Composition

    Directory of Open Access Journals (Sweden)

    Dumitru Bulgariu

    2002-04-01

    Full Text Available The separation and concetration of minerals from zeolitic volcanic tuffs represent one of the problems for which the literature not offer, to much practically solutions. The experimental strategy used by as, for the separation minerals from zeolitic volcanic tuffs to comprise the following methods: heavy liquids separation; magnetic separation and electrophoresis separation. For zeolites, silica polymorphs, feldspars and other minerals separated from zeolitic volcanic tuffs, the work eighth conditions and the proper experimental strategy efficiency has been estabilish. The purity for mineral fractions can be separated has been between 95.0 – 99.6 %.

  4. Zeolite Membranes in Catalysis—From Separate Units to Particle Coatings

    Directory of Open Access Journals (Sweden)

    Radostina Dragomirova

    2015-12-01

    Full Text Available Literature on zeolite membranes in catalytic reactions is reviewed and categorized according to membrane location. From this perspective, the classification is as follows: (i membranes spatially decoupled from the reaction zone; (ii packed bed membrane reactors; (iii catalytic membrane reactors and (iv zeolite capsuled catalyst particles. Each of the resulting four chapters is subdivided by the kind of reactions performed. Over the whole sum of references, the advantage of zeolite membranes in catalytic reactions in terms of conversion, selectivity or yield is evident. Furthermore, zeolite membrane preparation, separation principles as well as basic considerations on membrane reactors are discussed.

  5. Isomerization of glucose into fructose by environmentally friendly Fe/β zeolite catalysts.

    Science.gov (United States)

    Xu, Siquan; Zhang, Lei; Xiao, Kehao; Xia, Haian

    2017-06-29

    Herein, the environmentally friendly Fe/β zeolite for glucose isomerization to fructose in aqueous media was reported for the first time. The effects of various reaction conditions including reaction temperature, reaction time, catalyst dosage, etc. on the isomerization reaction over Fe/β zeolite were studied in detail. Under the optimized conditions, yield of fructose higher than 20% were obtained. Moreover, the Fe/β zeolite catalysts were stable and remained constant catalytic activity after five consecutive runs. The possible active Fe species for isomerization of glucose in Fe/β zeolite is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. REMOVAL OF DIQUATERNARY AMMONIUM CATIONS FROM AS-SYNTHESIZED SSZ-16 ZEOLITE

    Directory of Open Access Journals (Sweden)

    Tatana Supinkova

    2017-07-01

    Full Text Available Zeolites are stable microporous aluminosilicates with numerous applications in chemical technology such as separation of species and catalytic transformations. Our study is focused on a weakly explored zeolite SSZ-16 with pore constrictions defined by 8-membered oxygen rings. Key results are the preparation of Et6-diquat-5 dication used as a structure directing agent (SDA and finding the optimum synthesis conditions with respect to zeolite phase purity. Stability of SDA was examined in conditions similar to those of autoclave synthesis (concentration, pH, temperature. Moreover, the content and location of SDA species in zeolite phase and conditions of SDA decomposition were investigated.

  7. Synthesis of Zeolite Nanomolecular Sieves of Different Si/Al Ratios

    Directory of Open Access Journals (Sweden)

    Pankaj Sharma

    2015-01-01

    Full Text Available Nanosized zeolite molecular sieves of different Si/Al ratios have been prepared using microwave hydrothermal reactor (MHR for their greater application in separation and catalytic science. The as-synthesized molecular sieves belong to four different type zeolite families: MFI (infinite and high silica, FAU (moderate silica, LTA (low silica and high alumina, and AFI (alumina rich and silica-free. The phase purity of molecular sieves has been assessed by X-ray diffraction (XRD analysis and morphological evaluation done by electron microscopy. Broad XRD peaks reveal that each zeolite molecular sieve sample is composed of nanocrystallites. Scanning electron microscopic images feature the notion that the incorporation of aluminum to MFI zeolite synthesis results in morphological change. The crystals of pure silica MFI zeolite (silicalite-1 have hexagon lump/disk-like shape, whereas MFI zeolite particles with Si/Al molar ratios 250 and 100 have distorted hexagonal lump/disk and pseudo spherical shapes, respectively. Furthermore, phase pure zeolite nanocrystals of octahedron (FAU, cubic (LTA, and rod (AFI shape have been synthesized. The average sizes of MFI, FAU, LTA, and AFI zeolite crystals are 250, 150, 50, and 3000 nm, respectively. Although the length of AFI zeolite rods is in micron scale, the thickness and width are of a few nanometers.

  8. Lithium modified zeolite synthesis for conversion of biodiesel-derived glycerol to polyglycerol

    Energy Technology Data Exchange (ETDEWEB)

    Ayoub, Muhammad, E-mail: muhammad.ayoub@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS, 31750, Tronoh, Perak, Malaysia and School of Chemical Engineering, Universiti Sains Malaysia, 43000, Pinang (Malaysia); Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my [School of Chemical Engineering, Universiti Sains Malaysia, 43000, Pinang (Malaysia); Inayat, Abrar, E-mail: abrar.inayat@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS, 31750, Tronoh, Perak (Malaysia)

    2014-10-24

    Basic zeolite has received significant attention in the catalysis community. These zeolites modified with alkaline are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. The present paper covers the preparation of lithium modified zeolite Y (Li-ZeY) and its activity for solvent free conversion of biodiesel-derived glycerol to polyglycerol via etherification process. The modified zeolite was well characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Nitrogen Adsorption. The SEM images showed that there was no change in morphology of modified zeolite structure after lithium modification. XRD patterns showed that the structure of zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N{sub 2} adsortion-desorption technique and found some changes in surface area and pore size. In addition, the basic strength of prepared materials was measured by Hammet indicators and found that basic strength of Li-ZeY was highly improved. This modified zeolite was found highly thermal stable and active heterogamous basic catalyst for conversion of solvent free glycerol to polyglycerol. This reaction was conducted at different temperatures and 260 °C was found most active temperature for this process for reaction time from 6 to 12 h over this basic catalyst in the absence of solvent.

  9. Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts.

    Science.gov (United States)

    Choi, Minkee; Na, Kyungsu; Kim, Jeongnam; Sakamoto, Yasuhiro; Terasaki, Osamu; Ryoo, Ryong

    2009-09-10

    Zeolites-microporous crystalline aluminosilicates-are widely used in petrochemistry and fine-chemical synthesis because strong acid sites within their uniform micropores enable size- and shape-selective catalysis. But the very presence of the micropores, with aperture diameters below 1 nm, often goes hand-in-hand with diffusion limitations that adversely affect catalytic activity. The problem can be overcome by reducing the thickness of the zeolite crystals, which reduces diffusion path lengths and thus improves molecular diffusion. This has been realized by synthesizing zeolite nanocrystals, by exfoliating layered zeolites, and by introducing mesopores in the microporous material through templating strategies or demetallation processes. But except for the exfoliation, none of these strategies has produced 'ultrathin' zeolites with thicknesses below 5 nm. Here we show that appropriately designed bifunctional surfactants can direct the formation of zeolite structures on the mesoporous and microporous length scales simultaneously and thus yield MFI (ZSM-5, one of the most important catalysts in the petrochemical industry) zeolite nanosheets that are only 2 nm thick, which corresponds to the b-axis dimension of a single MFI unit cell. The large number of acid sites on the external surface of these zeolites renders them highly active for the catalytic conversion of large organic molecules, and the reduced crystal thickness facilitates diffusion and thereby dramatically suppresses catalyst deactivation through coke deposition during methanol-to-gasoline conversion. We expect that our synthesis approach could be applied to other zeolites to improve their performance in a range of important catalytic applications.

  10. Effect of combination of irradiation and zeolite on pyrolysis of polymer materials

    International Nuclear Information System (INIS)

    Hasegawa, S.; Takesita, H.; Yoshii, F.; Makuuchi, K.; Nishimoto, S.I.

    1998-01-01

    Fo0r recycling of waste polymers, degradation behavior of polypropylene (PP) and polyoxymethylene (POM) was studied by a combination of radiolysis and thermolysis methods. The results revealed that thermal degradation temperature of PP was significantly reduced when PP was irradiated in the presence of zeolite. Irradiation induced temperature reduction depended on zeolite structure and composition as well as on the morphology of the mixture. In the presence of zeolite, a series of oxidized products were formed. Initial temperature for the pyrolysis of POM was depressed by irradiation and the irradiated POM had lower final temperature of pyrolysis in the presence of zeolite

  11. Effects of ultrasonic irradiation on crystallization and structural properties of EMT-type zeolite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Eng-Poh, E-mail: epng@usm.my [School of Chemical Sciences, Universiti Sains Malaysia, USM, 11800 Penang (Malaysia); Awala, Hussein [Laboratoire Catalyse & Spectrochimie, CNRS-ENSICAEN, Université de Caen (France); Ghoy, Jia-Pei [School of Chemical Sciences, Universiti Sains Malaysia, USM, 11800 Penang (Malaysia); Vicente, Aurélie [Laboratoire Catalyse & Spectrochimie, CNRS-ENSICAEN, Université de Caen (France); Ling, Tau Chuan [Institute of Biological Sciences, Faculty of Science, University of Malaya (Malaysia); Ng, Yun Hau [School of Chemical Engineering, The University of New South Wales, Sydney (Australia); Mintova, Svetlana [Laboratoire Catalyse & Spectrochimie, CNRS-ENSICAEN, Université de Caen (France); Adam, Farook, E-mail: farook@usm.my [School of Chemical Sciences, Universiti Sains Malaysia, USM, 11800 Penang (Malaysia)

    2015-06-01

    Synthesis of EMT zeolite nanocrystals from rice husk ash biomass (RHA) under continuous ultrasonic irradiation is reported. The aging, nucleation and crystallization stages of EMT zeolite in the system were monitored at ambient temperature, and compared with the conventional hydrothermal method. It was found that ultrasonic wave induced rapid crystal growth of the nanosized EMT zeolite. Complete crystallization of EMT nanocrystals was achieved within 24 h which was much faster than conventional hydrothermal synthesis (36 h). Furthermore, XRD and TEM analyses revealed that more nuclei were formed during the nucleation stage, allowing the preparation of smaller zeolite nanocrystals with high crystallinity. The results also showed that sonocrystallization produced EMT zeolite with high yield (ca. 80%). The ultrasound-prepared EMT nanocrystals were also found to have high porosity and high hydrophilicity, making the material promising for water sorption applications including vapor sensing, heat pump and adsorption technologies. - Highlights: • Nanosized EMT zeolites are formed from rice husk ash under ultrasonic irradiation. • The effects of ultrasonic waves in nanosized EMT zeolite synthesis are studied. • Ultrasound induces rapid crystal growth and produces high zeolite yield. • Smaller zeolite nanocrystals with high crystallinity and large defect sites are obtained. • Improved surface hydrophilicity of crystals is beneficial for water sorption applications.

  12. Sintesis Zeolit dari Abu Layang dengan Metode Hidrotermal dan Uji Adsorptivitas Terhadap Logam Timbal (Pb

    Directory of Open Access Journals (Sweden)

    Rismang Rismang

    2017-12-01

    Full Text Available Synthesis of zeolite from fly ash obtained from Jeneponto Bosowa energypower plant have been conducted by hydrothermal method. This study was conducted to determine the characteristics of a synthetic zeolite fly ash and synthetic zeolite adsortivitas to metallic lead (Pb. Fly ash which is the main source of silica prepared by the process of concentration variations reflux with HCl (2M; 3M; 4M and 5M. Manufacture of sodium silicate solution by dissolving NaOH fly ash into the proportion of 10 ml per 1 gram of fly ash. Synthesis process by adding sodium aluminate into a solution of sodium silicate with a ratio of 1: 1 and then put in an autoclave as a hydrothermal process at a temperature of 120 ° C for 2 hours. Hydrothermal product obtained is characterized by X-Ray Diffraction (XRD to determine the type and intensity of the zeolite crystals obtained from the synthesis process. XRD analysis results showed the highest intensities are in the process of reflux 5M with type zeolite obtained in the form of zeolite ITQ-34, zeolite (K, Ba -G, L, sodalite and alumina-silica minerals such as eucryptit and aluminum oxide. The resulting zeolite able to absorb the metals Pb2+ at 99.04%, which is made with a concentration of 20 ppm of 50 mL with a mass of 1 gram of zeolite.

  13. A tangent formula derived from Patterson-function arguments. Pt. 3. Structure determination of zeolitic and layered materials from low-resolution powder diffraction data

    International Nuclear Information System (INIS)

    Rius, J.; Sane, J.; Miravitlles, C.; Gies, H.; Marler, B.; Oberhagemann, U.

    1995-01-01

    The viability of solving the structure type of zeolitic and layered materials applying multisolution direct methods to low-resolution (∼2.2 A) powder diffraction data is shown. The phases are refined with the tangent formula derived from Patterson-function arguments and the correct phase sets are discriminated with the conventional figures of merit. The two test examples presented are (a) the already known tetragonal zeolite ZSM-11 (space group I anti 4m2) at 2.3 A resolution and (b) the hitherto unknown layer silicate RUB-15 (Ibam) at 2.2 A resolution. In both cases, the tetrahedral Si units appear as resolved peaks in the Fourier maps computed with the phases of the highest-ranked direct-methods solutions. (orig.)

  14. Constrained Supersymmetric Flipped SU(5) GUT Phenomenology

    CERN Document Server

    Ellis, John; Olive, Keith A

    2011-01-01

    We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, $M_{in}$, above the GUT scale, $M_{GUT}$. We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino and the lighter stau is sensitive to $M_{in}$, as is the relationship between the neutralino mass and the masses of the heavier Higgs bosons. For these reasons, prominent features in generic $(m_{1/2}, m_0)$ planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to $M_{in}$, as we illustrate for several cases with tan(beta)...

  15. Constraining Amazonian Methane Emission from Wetlands

    Science.gov (United States)

    Boesch, Hartmut; Parker, Robert; Webb, Alex; Wilson, Chris; Chipperfield, Martyn; Gloor, Emanuel; Feng, Liang; Palmer, Paul

    2017-04-01

    The Amazon Basin contains large wetland ecosystems which are important sources of methane (CH4). Spaceborne observations provide detailed information about the spatio-temporal distributions of atmospheric methane over the Amazon Basin which will provide a strong constrain on the underlying emissions and their year to year variations. Methane observations from space are available from the Japanese GOSAT instrument since 2009. We use the proxy retrieval method which provides much greater coverage over the Amazon region compared to so-called Full-Physics methods due to their lower sensitivity to thin clouds. Validation of GOSAT retrieval over the Amazon using the ground-based TCCON network is currently not possible due to a lack of data and we have used routine aircraft profiles to show that GOSAT columns are sufficiently accurate for estimating surface flux for the region. Using a variational flux inverse system together with the 3-D atmospheric chemical transport model TOMCAT, we infer surface fluxes for the Amazon region from GOSAT observations which are used to analyse the spatial distribution of methane wetlands emissions as well as annual variations in emissions with a focus on periods 2011/2012 and 2013/14 which are characterized by large variations in rainfall.

  16. Power Absorption by Closely Spaced Point Absorbers in Constrained Conditions

    DEFF Research Database (Denmark)

    De Backer, G.; Vantorre, M.; Beels, C.

    2010-01-01

    , representing the wave climate at Westhinder on the Belgian Continental Shelf The impact of slamming, stroke and force restrictions on the power absorption is evaluated and optimal PTO parameters are determined For multiple bodies optimal control parameters (CP) are not only dependent on the incoming waves...... are applied to two array layouts consisting of 12 buoys in a staggered grid and 21 buoys in an aligned grid Compared to DO, it was found that individually optimising the CP increased the energy absorption at Westhinder with about 16-18% for the two layouts, respectively...

  17. How to constrain inflationary parameter space with minimal priors

    International Nuclear Information System (INIS)

    Hamann, Jan; Lesgourgues, Julien; Valkenburg, Wessel

    2008-01-01

    We update constraints on the Hubble function H(φ) during inflation, using the most recent cosmic microwave background (CMB) and large scale structure (LSS) data. Our main focus is on a comparison between various commonly used methods of calculating the primordial power spectrum via analytical approximations and the results obtained by integrating the exact equations numerically. In each case, we impose naive, minimally restrictive priors on the duration of inflation. We find that the choice of priors has an impact on the results: the bounds on inflationary parameters can vary by up to a factor of two. Nevertheless, it should be noted that, within the region allowed by the minimal prior of the exact method, the accuracy of the approximations is sufficient for current data. We caution, however, that a careless minimal implementation of the approximative methods allows models for which the assumptions behind the analytical approximations fail, and recommend using the exact numerical method for a self-consistent analysis of cosmological data

  18. Performance of Closely Spaced Point Absorbers with Constrained Floater Motion

    DEFF Research Database (Denmark)

    De Backer, G.; Vantorre, M.; Beels, C.

    2009-01-01

    The performance of a wave energy converter array of twelve heaving point absorbers has been assessed numerically in a frequency domain model. Each point absorber is assumed to have its own linear power take-off. The impact of slamming, stroke and force restrictions on the power absorption...

  19. Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments

    Directory of Open Access Journals (Sweden)

    Yasuhiro Ishida

    2011-01-01

    Full Text Available In liquid crystals (LCs, molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of “controlling molecular events within LC media” seems reasonable. As a suitable system for investigating this challenge, we have recently developed a new class of ionic LCs; the salts of amphiphilic carboxylic acids with 2-amino alcohols, or those of carboxylic acids with amphiphilic 2-amino alcohols, have a strong tendency to exhibit thermotropic LC phases. Because of the noncovalent nature of the interaction between molecules, one of the two components can easily be exchanged with, or transformed into, another molecule, without distorting the original LC architecture. In addition, both components are common organic molecules, and a variety of compounds are easily available. Taking advantage of these characteristics, we have succeeded in applying two‑component LCs as chiral media for molecular recognition and reactions. This review presents an overview of our recent studies, together with notable reports related to this field.

  20. Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments.

    Science.gov (United States)

    Ishida, Yasuhiro

    2011-01-11

    In liquid crystals (LCs), molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of "controlling molecular events within LC media" seems reasonable. As a suitable system for investigating this challenge, we have recently developed a new class of ionic LCs; the salts of amphiphilic carboxylic acids with 2-amino alcohols, or those of carboxylic acids with amphiphilic 2-amino alcohols, have a strong tendency to exhibit thermotropic LC phases. Because of the noncovalent nature of the interaction between molecules, one of the two components can easily be exchanged with, or transformed into, another molecule, without distorting the original LC architecture. In addition, both components are common organic molecules, and a variety of compounds are easily available. Taking advantage of these characteristics, we have succeeded in applying two‑component LCs as chiral media for molecular recognition and reactions. This review presents an overview of our recent studies, together with notable reports related to this field.

  1. Mesh dependence in PDE-constrained optimisation an application in tidal turbine array layouts

    CERN Document Server

    Schwedes, Tobias; Funke, Simon W; Piggott, Matthew D

    2017-01-01

    This book provides an introduction to PDE-constrained optimisation using finite elements and the adjoint approach. The practical impact of the mathematical insights presented here are demonstrated using the realistic scenario of the optimal placement of marine power turbines, thereby illustrating the real-world relevance of best-practice Hilbert space aware approaches to PDE-constrained optimisation problems. Many optimisation problems that arise in a real-world context are constrained by partial differential equations (PDEs). That is, the system whose configuration is to be optimised follows physical laws given by PDEs. This book describes general Hilbert space formulations of optimisation algorithms, thereby facilitating optimisations whose controls are functions of space. It demonstrates the importance of methods that respect the Hilbert space structure of the problem by analysing the mathematical drawbacks of failing to do so. The approaches considered are illustrated using the optimisation problem arisin...

  2. Fabrication of hydrophobic zeolites using triethoxyfluorosilane and their application as supports for TiO(2) photocatalysts.

    Science.gov (United States)

    Kuwahara, Yasutaka; Kamegawa, Takashi; Mori, Kohsuke; Yamashita, Hiromi

    2008-10-21

    Hydrophobically modified Y-zeolites were prepared by simple modification with triethoxyfluorosilane (TEFS). These zeolites, used as supports, enhanced the efficiency of deposited TiO(2) for the photocatalytic degradation of organics diluted in water.

  3. Thermophysical properties of novel zeolite materials for sorption cycles

    KAUST Repository

    Thu, Kyaw

    2013-08-01

    his article discusses the thermophysical properties of zeolite-based adsorbents. Three types of zeolite (Z-01, Z-02 and Z-05) with different chemical compositions developed by Mitsubishi Plastics, Inc. are analyzed for possible applications in adsorption chillers and desalination cycles driven by low-temperature waste heat sources. The experiments are performed using static volumetric method with N2 gas sorption at 77 K. Thermophysical properties such as pore surface area, micropore volume and pore size distribution are evaluated using standard multipoint Brunauer-Emmett-Teller (BET) and Non-Local Density Functional Theory (NLDFT) methods. It is observed that Aluminosilicate functionalized Z-02 exhibits the highest surface area with huge micropore volume. © (2013) Trans Tech Publications, Switzerland.

  4. Structural simulation of natural zeolites; Simulacion estructural de zeolitas naturales

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez P, E.; Carrera G, L.M. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The application of X-ray diffraction (XRD) in the study of crystalline structures of the natural and modified zeolites allows the identification, lattice parameter determination and the crystallinity grade of the sample of interest. Until two decades ago, simulation methods of X-ray diffraction patterns were developed with which was possible to do reliable determinations of their crystalline structure. In this work it is presented the first stage of the crystalline structure simulation of zeolitic material from Etla, Oaxaca which has been studied for using it in the steam production industry and purification of industrial water. So that the natural material was modified for increasing its sodium contents and this material in its turn was put in contact with aqueous solutions of Na, Mg and Ca carbonates. All the simulations were done with the Lazy-Pulverix method. The considered phase was clinoptilolite. It was done the comparison with three clinoptilolite reported in the literature. (Author)

  5. Removal of uranium from water media by bentonite and zeolite

    International Nuclear Information System (INIS)

    Viglasova, E.; Krajnak, A.; Galambos, M.; Rosskopfova, O.

    2014-01-01

    The removal and recovery of uranium from contaminated surface, environment and ground water, as result of nuclear industries, has attracted more and more attentions. Several methods are available for removing of uranium, but adsorption among the others, is the most attractive. In case of management of radioactive waste, the adsorption of radionuclides plays significant role. Among the natural sorbents applied to the adsorption of uranium zeolites and bentonites offer a number of advantages. The main aims of this work are investigations of adsorption properties of Greek zeolite Metaxades and Greek bentonite Kimolos during adsorption of uranium from water solutions, comparison of their adsorption characteristics, fitting with isotherms (Freundlich, Langmuir and DR isotherm) and its behaviour during kinetics process influenced by temperature. (authors)

  6. Modified Asphalt Binder with Natural Zeolite for Warm Mix Asphalt

    Directory of Open Access Journals (Sweden)

    Dubravský Marián

    2015-11-01

    Full Text Available In recent years, warm mix asphalt (WMA is becoming more and more used in the asphalt industry. WMA provide a whole range of benefits, whether economic, environmental and ecological. Lower energy consumption and less pollution is the most advantages of this asphalt mixture. The paper deals with the addition of natural zeolite into the sub base asphalt layers, which is the essential constituent in the construction of the road. Measurement is focused on basic physic – mechanical properties declared according to the catalog data sheets. The aim of this article is to demonstrate the ability of addition the natural zeolite into the all asphalt layers of asphalt pavement. All asphalt mixtures were compared with reference asphalt mixture, which was prepared in reference temperature.

  7. GREEN CHEMISTRY. Shape-selective zeolite catalysis for bioplastics production.

    Science.gov (United States)

    Dusselier, Michiel; Van Wouwe, Pieter; Dewaele, Annelies; Jacobs, Pierre A; Sels, Bert F

    2015-07-03

    Biodegradable and renewable polymers, such as polylactic acid, are benign alternatives for petrochemical-based plastics. Current production of polylactic acid via its key building block lactide, the cyclic dimer of lactic acid, is inefficient in terms of energy, time, and feedstock use. We present a direct zeolite-based catalytic process, which converts lactic acid into lactide. The shape-selective properties of zeolites are essential to attain record lactide yields, outperforming those of the current multistep process by avoiding both racemization and side-product formation. The highly productive process is strengthened by facile recovery and practical reactivation of the catalyst, which remains structurally fit during at least six consecutive reactions, and by the ease of solvent and side-product recycling. Copyright © 2015, American Association for the Advancement of Science.

  8. Fission product removal from molten salt using zeolite

    International Nuclear Information System (INIS)

    Pereira, C.; Babcock, B.D.

    1996-01-01

    Spent nuclear fuel (SNF) can be treated in a molten salt electrorefiner for conversion into metal and mineral waste forms for geologic disposal. The fuel is dissolved in molten chloride salt. Non-transuranic fission products in the molten salt are ion-exchanged into zeolite A, which is subsequently mixed with glass and consolidated. Zeolite was found to be effective in removing fission product cations from the molten salt. Breakthrough of cesium and the alkaline earths occurred more rapidly than was observed for the rare earths. The effluent composition as a function of time is presented, as well as results for the distribution of fission products along the length of the column. Effects of temperature and salt flow rate are also discussed

  9. Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, Raz [Univ. of California, Berkeley, CA (United States)

    1993-07-01

    Goal is to study the organization and structures of guest atoms and molecules and their reactions on internal surfaces within pores of zeolites and aluminophosphate molecular sieves. 27Al and 23Na double rotation NMR (DOR) is used since it removes the anisotropic broadening in NMR spectra of quadrupolar nuclei, thus increasing resolution. This work concentrates on probing aluminum framework atoms in aluminophosphate molecular sieves and sodium extra framework cations in porous aluminosilicates. In aluminophosphates, ordering and electronic environments of the framework 27Al nuclei are modified upon adsorption of water molecules within the channels; a relation is sought between the sieve channel topology and the organization of adsorbed water, as well as the interaction between the Al nuclei and the water molecules. Extra framework Na+ cations are directly involved in adsorption processes and reactions in zeolite cavities.

  10. Impact of steel slag on the ammonium adsorption by zeolite and a new configuration of zeolite-steel slag substrate for constructed wetlands.

    Science.gov (United States)

    Shi, Pengbo; Jiang, Yingbo; Zhu, Hongtao; Sun, Dezhi

    2017-07-01

    The CaO dissolution from slag, as well as the effects of influencing parameters (i.e. pH and Ca 2+ concentration) on the ammonium adsorption onto zeolite, was systematically studied in this paper. Modeling results of Ca 2+ and OH - release from slag indicated that pseudo-second-order reaction had a better fitness than pseudo-first-order reaction. Changing pH value from 7 to 12 resulted in a drastic reduction of the ammonium adsorption capacity on zeolite, from the peak adsorption capacity at pH 7. High Ca 2+ concentration in solution also inhibited the adsorption of ammonium onto zeolite. There are two proposed mechanisms for steel slag inhibiting the ammonium adsorption capacity of zeolite. On the one hand, OH - released from steel slag can react with ammonium ions to produce the molecular form of ammonia (NH 3 ·H 2 O), which would cause the dissociation of NH 4 + from zeolite. On the other hand, Ca 2+ could replace the NH 4 + ions to adhere onto the surface of zeolite. An innovative substrate filling configuration with zeolite placed upstream of the steel slag was then proposed to eliminate the disadvantageous effects of steel slag. Experimental results showed that this novel filling configuration was superior to two other filling configurations in terms of ammonium removal.

  11. Conditions for the Solvability of the Linear Programming Formulation for Constrained Discounted Markov Decision Processes

    Energy Technology Data Exchange (ETDEWEB)

    Dufour, F., E-mail: dufour@math.u-bordeaux1.fr [Institut de Mathématiques de Bordeaux, INRIA Bordeaux Sud Ouest, Team: CQFD, and IMB (France); Prieto-Rumeau, T., E-mail: tprieto@ccia.uned.es [UNED, Department of Statistics and Operations Research (Spain)

    2016-08-15

    We consider a discrete-time constrained discounted Markov decision process (MDP) with Borel state and action spaces, compact action sets, and lower semi-continuous cost functions. We introduce a set of hypotheses related to a positive weight function which allow us to consider cost functions that might not be bounded below by a constant, and which imply the solvability of the linear programming formulation of the constrained MDP. In particular, we establish the existence of a constrained optimal stationary policy. Our results are illustrated with an application to a fishery management problem.

  12. The ADOR mechanism for the synthesis of new zeolites

    Czech Academy of Sciences Publication Activity Database

    Eliášová, Pavla; Opanasenko, Maksym; Wheatley, P. S.; Shamzhy, Mariya; Mazur, Michal; Nachtigall, P.; Roth, Wieslaw Jerzy; Morris, R. E.; Čejka, Jiří

    2015-01-01

    Roč. 44, č. 20 (2015), s. 7177-7206 ISSN 0306-0012 R&D Projects: GA ČR GBP106/12/G015; GA ČR(CZ) GP14-30898P Institutional support: RVO:61388955 Keywords : STRUCTURE -DIRECTING AGENTS * LARGE-PORE ZEOLITES * PILLARED MOLECULAR-SIEVE Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 34.090, year: 2015

  13. Zeolite and bentonite as caesium binders in reindeer feed

    Directory of Open Access Journals (Sweden)

    Birgitta Åhman

    1990-09-01

    Full Text Available The effects of zeolite and bentonite on the accumulation and excretion of radiocaesium (Cs-137 in reindeer were studied in two feeding experiments. Six animals in each experiment were given lichens contaminated with radiocaesium from fallout after the Chernobyl nuclear power plant accident. In addition, they were fed pellets containing bentonite (Experiment I or zeolite (Experiment II. Two animals, controls, in each experiment received no caesium-binder. The activity concentration of radiocaesium in blood was used to evalute the radiocaesium level in the body. Faeces and urine were collected to measue the excration of radiocaesium. The animals in Experiment I were depleted of radiocaesium before the start of the experiment. After three weeks, with an intake of 17 - 18 kBq Cs-137/day, the controls had reached activity concentrations of radiocaesium in blood corresponding to 4 - 4.5 kBq Cs-137/kg in muscle. Reindeer fed 23 or 46 g of bentonite per day stabilized at values below 0.8 kfiq/kg in muscle. In Experiment II, the reindeer started with radiocaesium activity concentrations in blood corresponding to 2 - 4.5 kBq Cs-137/kg in muscle. After four weeks of feeding, with an intake at about 8.5 kBq Cs-137/day, controls had increased their radiocaesium values by an average of 40%. Reindeer receiving 25 or 50 g zeolite per day decreased with 18 and 45%, respectively. Net absorption of radiocaesium from the gastro-intestinal tract was calculated at 50 -70% in animals receiving no caesium-binder. Reindeer fed bentonite had an absorption below 10% while those fed zeolite absorbed around 35%.

  14. High flux zeolite membranes for efficient production of biofuels

    OpenAIRE

    Sandström, Linda

    2012-01-01

    The greenhouse effect and the limited fossil oil resources have increased the demand for renewable fuels. Zeolite membranes have potential applications in numerous separation processes, and could be useful in the development of efficient processes for renewable fuel production.Synthesis gas is a gas mixture containing mainly carbon monoxide, hydrogen and carbon dioxide. Synthesis gas produced from biomass usually contains more carbon dioxide than desired, and it also contains hydrogen sulphid...

  15. Metal exchanged zeolites for catalytic decomposition of N2O

    Czech Academy of Sciences Publication Activity Database

    Lebhsetwar, N.; Dhakad, M.; Biniwale, R.; Mitsuhasi, T.; Haneda, H.; Reddy, P.S.S.; Bakardjieva, Snejana; Šubrt, Jan; Kumar, S.; Kumar, V.; Saiprasad, P.; Rayalu, S.

    2009-01-01

    Roč. 141, 1-2 (2009), s. 205-210 ISSN 0920-5861. [18th National Symposium and Indo-US seminar on Catalysis. Dehradun, 16.04.2007-18.04.2007] Grant - others:CSIR(IN) SIP-16 (1,3) Institutional research plan: CEZ:AV0Z40320502 Keywords : N2O decomposition * catalyst * zeolite Subject RIV: CA - Inorganic Chemistry Impact factor: 3.526, year: 2009

  16. Epitaxially Grown Layered MFI–Bulk MFI Hybrid Zeolitic Materials

    KAUST Repository

    Kim, Wun-gwi

    2012-11-27

    The synthesis of hybrid zeolitic materials with complex micropore-mesopore structures and morphologies is an expanding area of recent interest for a number of applications. Here we report a new type of hybrid zeolite material, composed of a layered zeolite material grown epitaxially on the surface of a bulk zeolite material. Specifically, layered (2-D) MFI sheets were grown on the surface of bulk MFI crystals of different sizes (300 nm and 10 μm), thereby resulting in a hybrid material containing a unique morphology of interconnected micropores (∼0.55 nm) and mesopores (∼3 nm). The structure and morphology of this material, referred to as a "bulk MFI-layered MFI" (BMLM) material, was elucidated by a combination of XRD, TEM, HRTEM, SEM, TGA, and N2 physisorption techniques. It is conclusively shown that epitaxial growth of the 2-D layered MFI sheets occurs in at least two principal crystallographic directions of the bulk MFI crystal and possibly in the third direction as well. The BMLM material combines the properties of bulk MFI (micropore network and mechanical support) and 2-D layered MFI (large surface roughness, external surface area, and mesoporosity). As an example of the uses of the BMLM material, it was incorporated into a polyimide and fabricated into a composite membrane with enhanced permeability for CO2 and good CO2/CH4 selectivity for gas separations. SEM-EDX imaging and composition analysis showed that the polyimide and the BMLM interpenetrate into each other, thereby forming a well-adhered polymer/particle microstructure, in contrast with the defective interfacial microstructure obtained using bare MFI particles. Analysis of the gas permeation data with the modified Maxwell model also allows the estimation of the effective volume of the BMLM particles, as well as the CO2 and CH4 gas permeabilities of the interpenetrated layer at the BMLM/polyimide interface. © 2012 American Chemical Society.

  17. Use of zeolite to neutralise nickel in a soil environment.

    Science.gov (United States)

    Boros-Lajszner, Edyta; Wyszkowska, Jadwiga; Kucharski, Jan

    2017-12-30

    Nickel is a heavy metal which is a stable soil pollutant which is difficult to remediate. An attempt to reduce its impact on the environment can be made by changing its solubility. The right level of hydrogen ions and the content of mineral and organic colloids are crucial in this regard. Therefore, methods to neutralise heavy metals in soil are sought. There are no reports in the literature on the possibility of using minerals in the detoxication of a soil environment contaminated with metals. It is important to fill the gap in research on the effect of zeolites on the microbiological, biochemical and physicochemical properties of soils under pressure from heavy metals. Therefore, a pot experiment was conducted on two soils which examined the effect of various levels of contamination of soil with nickel on the activity of soil enzymes, physical and chemical properties and growth and development of plants. An alleviating effect of zeolite Bio.Zeo.S.01 on the negative impact of nickel on the soil and a plant (oats) was examined. The enzyme activity and the oat yield were found to be significantly and negatively affected by an excess of nickel in the soil, regardless of the soil type. The metal was accumulated more in the oat roots than in the above-ground parts. An addition of zeolite decreased the level of accumulation of nickel in oats grown only on sandy-silty loam. Zeolite Bio.Zeo.S.01 used in the study only slightly alleviated the negative effect of nickel on the biochemical properties of soil. Therefore, its usability in the remediation of soil contaminated with nickel is small.

  18. PHENOL OXIDATION USING NATURAL ZEOLITE SUPPORTED METAL ION CATALYST

    Directory of Open Access Journals (Sweden)

    Sri Wardhani

    2010-06-01

    Full Text Available Phenol which contained in waste water has to be reduced and it could be done by oxygen oxidation.  In order to increase the rate of reaction it was needed a catalyst. In this research the capability of various catalysts, namely zeolite-Zn(II, zeolite-Cu(II and zeolite-Co(IIin oxidation of phenol has been investigated. The aim of this research was to study the type of metal ion catalyst towards the percentage of oxidated phenol. The oxidation process were carried out in an aqueous phenol of 100 ppm with oxygen flow rate of 200 mL/min. in the presence of catalysts with 0.2M of initial impregnation concentration. The capabilities of catalysts were performed by calculating the activation energy and it was done at two different temperatures, i.e. 70 and 90 oC. The percentage of oxidated phenol was determinated by measuring its concentration using UV-VIS spectrophotometer. In addition, the impregnated metal was calculated by measuring the ion concentration remains in the filtrate solution and it was determined using Atomic Absorption Spectrophotometer. The results showed that metal ion types affected the catalytic activity. The order of phenol oxidationactivity decreased as Co(II > Cu(II > Zn(II. The surface characteristics of catalysts were supported by pore volume and pore diameter i.e 0.009 cm3/g and 16.59 Å for Zn(II whereas specific surface area was 10.32 m2/g for Zn(II, 0.004 cm3/g and 24.37 Å for Cu(II whereas specific surface area was 3.57 m2/g for Cu(II, 0.001 cm3/g and 19.63 Å for Co(II whereas specific surface area was 10.26m2/g for Co(II.   Keywords: phenol,natural zeolite, catalyst, oxidation

  19. Butane isomer separation with composite zeolite MFI mebranes

    Czech Academy of Sciences Publication Activity Database

    Hrabánek, Pavel; Zikánová, Arlette; Bernauer, B.; Fíla, V.; Kočiřík, Milan

    2009-01-01

    Roč. 245, 1-3 (2009), s. 437-443 ISSN 0011-9164 R&D Projects: GA ČR GA203/07/1443; GA AV ČR KAN400720701; GA AV ČR(CZ) 1QS401250509 Institutional research plan: CEZ:AV0Z40400503 Keywords : zeolite MFI * membranes * separation * butane isomers Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.034, year: 2009

  20. Incorporation of aluminium and iron into the zeolite MCM-58

    Czech Academy of Sciences Publication Activity Database

    Košová, Gabriela; Ernst, S.; Hartmann, M.; Čejka, Jiří

    -, č. 6 (2005), s. 1154-1161 ISSN 1434-1948 R&D Projects: GA AV ČR(CZ) KJB4040402; GA ČR GA203/03/0804 Grant - others:Volkswagen-Stiftung(DE) I/75 886 Institutional research plan: CEZ:AV0Z40400503 Keywords : acidity * aluminum * kinetics * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.514, year: 2005

  1. Characterization of zeolite-based coatings for adsorption heat pumps

    CERN Document Server

    Freni, Angelo; Bonaccorsi, Lucio; Chmielewski, Stefanie; Frazzica, Andrea; Calabrese, Luigi; Restuccia, Giovanni

    2015-01-01

    This book proposes a radically new approach for characterizing thermophysical and mechanical properties of zeolite-based adsorbent coatings for Adsorptive Heat Transformers (AHT). It presents a developed standard protocol for the complete characterization of advanced coated adsorbers. Providing an in-depth analysis of the different procedures necessary for evaluating the performance of adsorbers, it also presents an analysis of their stability under the hydrothermal and mechanical stresses during their entire life cycle. Adsorptive Heat Transformers (AHT), especially adsorption chillers and

  2. Alcohol and water adsorption in zeolitic imidazolate frameworks

    KAUST Repository

    Zhang, Ke

    2013-01-01

    Alcohol (methanol, ethanol, 1-propanol, 2-propanol and 1-butanol) and water vapor adsorption in zeolitic imidazolate frameworks (ZIF-8, ZIF-71 and ZIF-90) with similar crystal sizes was systematically studied. The feasibility of applying these ZIF materials to the recovery of bio-alcohols is evaluated by estimating the vapor-phase alcohol-water sorption selectivity. © 2013 The Royal Society of Chemistry.

  3. Constraining new physics models with isotope shift spectroscopy

    Science.gov (United States)

    Frugiuele, Claudia; Fuchs, Elina; Perez, Gilad; Schlaffer, Matthias

    2017-07-01

    Isotope shifts of transition frequencies in atoms constrain generic long- and intermediate-range interactions. We focus on new physics scenarios that can be most strongly constrained by King linearity violation such as models with B -L vector bosons, the Higgs portal, and chameleon models. With the anticipated precision, King linearity violation has the potential to set the strongest laboratory bounds on these models in some regions of parameter space. Furthermore, we show that this method can probe the couplings relevant for the protophobic interpretation of the recently reported Be anomaly. We extend the formalism to include an arbitrary number of transitions and isotope pairs and fit the new physics coupling to the currently available isotope shift measurements.

  4. Library Support for Resource Constrained Accelerators

    DEFF Research Database (Denmark)

    Brock-Nannestad, Laust; Karlsson, Sven

    2014-01-01

    Accelerators, and other resource constrained systems, are increasingly being used in computer systems. Accelerators provide power efficient performance and often provide a shared memory model. However, it is a challenge to map feature rich APIs, such as OpenMP, to resource constrained systems...

  5. How our biology constrains our science

    NARCIS (Netherlands)

    Vlerick, Michael

    2017-01-01

    Reasoning from a naturalistic perspective, viewing the mind as an evolved biological organ with a particular structure and function, a number of influential philosophers and cognitive scientists claim that science is constrained by human nature. How exactly our genetic constitution constrains

  6. Bayesian evaluation of inequality constrained hypotheses

    NARCIS (Netherlands)

    Gu, X.; Mulder, J.; Deković, M.; Hoijtink, H.

    2014-01-01

    Bayesian evaluation of inequality constrained hypotheses enables researchers to investigate their expectations with respect to the structure among model parameters. This article proposes an approximate Bayes procedure that can be used for the selection of the best of a set of inequality constrained

  7. On using cold baryogenesis to constrain the two-Higgs doublet model

    DEFF Research Database (Denmark)

    Tranberg, A.; Wu, B.

    2013-01-01

    We consider the creation of the cosmological baryon asymmetry in the Two Higgs Doublet Model. We imagine a situation where the masses of the five Higgs particles and the two Higgs vevs are constrained by collider experiments, and demonstrate how the requirement of successful baryogenesis can be u...... be used to further constrain the remaining 4-dimensional parameter space of the model. We numerically compute the asymmetry within the scenario of Cold Electroweak Baryogenesis, which is particularly straightforward to simulate reliably....

  8. Space station molecular sieve development

    Science.gov (United States)

    Chang, C.; Rousseau, J.

    1986-01-01

    An essential function of a space environmental control system is the removal of carbon dioxide (CO2) from the atmosphere to control the partial pressure of this gas at levels lower than 3 mm Hg. The use of regenerable solid adsorbents for this purpose was demonstrated effectively during the Skylab mission. Earlier sorbent systems used zeolite molecular sieves. The carbon molecular sieve is a hydrophobic adsorbent with excellent potential for space station application. Although carbon molecular sieves were synthesized and investigated, these sieves were designed to simulate the sieving properties of 5A zeolite and for O2/N2 separation. This program was designed to develop hydrophobic carbon molecular sieves for CO2 removal from a space station crew environment. It is a first phase effort involved in sorbent material development and in demonstrating the utility of such a material for CO2 removal on space stations. The sieve must incorporate the following requirements: it must be hydrophobic; it must have high dynamic capacity for carbon dioxide at the low partial pressure of the space station atmosphere; and it must be chemiclly stable and will not generate contaminants.

  9. Unexpected Molecular Sieving Properties of Zeolitic Imidazolate Framework-8.

    Science.gov (United States)

    Zhang, Chen; Lively, Ryan P; Zhang, Ke; Johnson, Justin R; Karvan, Oguz; Koros, William J

    2012-08-16

    We studied molecular sieving properties of zeolitic imidazolate framework-8 (ZIF-8) by estimating the thermodynamically corrected diffusivities of probe molecules at 35 °C. From helium (2.6 Å) to iso-C4H10 (5.0 Å), the corrected diffusivity drops 14 orders of magnitude. Our results further suggest that the effective aperture size of ZIF-8 for molecular sieving is in the range of 4.0 to 4.2 Å, which is significantly larger than the XRD-derived value (3.4 Å) and between the well-known aperture size of zeolite 4A (3.8 Å) and 5A (4.3 Å). Interestingly, because of aperture flexibility, the studied C4 hydrocarbon molecules that are larger than this effective aperture size still adsorb in the micropores of ZIF-8 with kinetic selectivities for iso-C4H8/iso-C4H10 of 180 and n-C4H10/iso-C4H10 of 2.5 × 10(6). These unexpected molecular sieving properties open up new opportunities for ZIF materials for separations that cannot be economically achieved by traditional microporous adsorbents such as synthetic zeolites.

  10. Sonochemical synthesis of zeolite NaP from clinoptilolite.

    Science.gov (United States)

    Behin, Jamshid; Kazemian, Hossein; Rohani, Sohrab

    2016-01-01

    In the present work, natural clinoptilolite was converted to zeolite NaP using ultrasonic energy, in which the transformation time shortened remarkably. The effect of post-synthesis treatment using conventional hydrothermal was also investigated. The synthesized powders were characterized by XRD, TGA/DTA, SEM, and PSD analysis. The results showed that, increasing the sonication time (energy) has no significant effect on the product's morphology. The crystallinity of the synthesized samples increased slightly with increasing sonication time, but their yield remained relatively unchanged. Furthermore, post-synthesis hydrothermal treatment showed very little influence on properties of the final product. Because the ultrasonic irradiation creates acoustic cavitation cracks on the surface structure of clinoptilolite particulates and increases the concentration of soluble alumino-silicate species, which favors the prevailing super-saturation, crystallization and crystal growth of zeolite NaP happen faster. The particles of zeolite NaP synthesized by ultrasonic irradiation consist of small crystallites of uniform size. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Zeolites on Mars: Possible environmental indicators in soils and sediments

    International Nuclear Information System (INIS)

    Ming, D.W.; Gooding, J.L.

    1988-01-01

    Weathering products should serve as indicators of weathering environments and may provide the best evidence of the nature of climate change on Mars. No direct mineralogical measurements of Martian regolith were performed by the Viking missions, but the biology and X-ray fluorescence experiments provided some information on the physiochemical properties of Martian regolith. Most post-Viking studies of candidate weathering products have emphasized phyllosilicates and Fe-oxides; zeolites are potentially important, but overlooked, candidate Martian minerals. Zeolites would be important on Mars for three different reasons. First, they are major sinks of atmospheric gases and, per unit mass, are stronger and more efficient sorbents than are phyllosilicates. Secondly, they can be virtually unique sorbents and shelters for organic compounds and possible catalysts for organic-based reactions. Finally, their exchangeable ions are good indicators of the chemical properties of solutions with which they have communicated. Accordingly, the search for information on past compositions of the Martian atmosphere and hydrosphere should find zeolites to be rich repositories

  12. Investigation of the thermal behavior of Philippine natural zeolites

    Science.gov (United States)

    Olegario-Sanchez, Eleanor; Felizco, Jenichi Clairvaux; Mulimbayan, Francis

    2017-12-01

    This study aims to investigate the thermal behavior of natural zeolites from Mangatarem, Pangasinan, Philippines. Results obtained from the XRD pattern revealed that the sample is largely composed of mordenite, a Type I zeolite. In the chemical analysis, Si and Al are proven to be the primary components of the sample, which is typical in an aluminosilicate material. It also has a high Si/Al ratio, which suggests that the material is hydrophilic and thermally stable. The TGA analysis showed that dehydration processes dominate the sample's reaction upon heating up to 1000 °C. The initial dehydration process led to a weight loss that is almost equivalent to the moisture content, as measured by chemical analysis. The succeeding weight loss is most probably due to the dehydration of tightly-bound water and cation dehydration. No structural collapse was observed even up to 1000 °C, which suggests that the material is ideal for industrial applications. Lastly, FTIR results revealed that heating the zeolitic tuff led to possible de-alumination.

  13. Synthesis and characterization of Ce doped MFI zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, Banani [Department of Chemistry, Gauhati University, Guwahati, Assam 781014 (India); Talukdar, Anup K., E-mail: anup_t@sify.com [Department of Chemistry, Gauhati University, Guwahati, Assam 781014 (India)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Cerium was incorporated into the tetrahedral position of MFI zeolite structure. Black-Right-Pointing-Pointer Unit cell volume increases with an increase of Ce content in the framework of MFI. Black-Right-Pointing-Pointer A band at 310 nm in the UV-vis spectra indicates Ce incorporation in MFI structure. Black-Right-Pointing-Pointer The mass loss (%) in the region 373-423 K decreases with increase of Ce in MFI. - Abstract: Ce doped MFI (mobil five) zeolites with different Si to (Ce + Al) and different Ce to Al ratios were synthesized by a hydrothermal synthesis method. All the samples were characterized by different techniques such as X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-vis diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The results showed that almost pure MFI phase was obtained in all cases with incorporation of cerium metal into the framework. The increase in unit cell parameters observed with an increase in Ce content is indicative of incorporation of Ce into the framework structure of microporous material MFI. Corroboration of the framework incorporation of Ce into the MFI zeolite structure was also obtained from the UV-vis DRS spectra by the presence of an absorption band at 280 nm. TGA and SEM of the samples provide complementary evidence for Ce incorporation into the framework MFI structure.

  14. Unexpected Molecular Sieving Properties of Zeolitic Imidazolate Framework-8

    KAUST Repository

    Zhang, Chen

    2012-08-16

    We studied molecular sieving properties of zeolitic imidazolate framework-8 (ZIF-8) by estimating the thermodynamically corrected diffusivities of probe molecules at 35 °C. From helium (2.6 Å) to iso-C 4H 10 (5.0 Å), the corrected diffusivity drops 14 orders of magnitude. Our results further suggest that the effective aperture size of ZIF-8 for molecular sieving is in the range of 4.0 to 4.2 Å, which is significantly larger than the XRD-derived value (3.4 Å) and between the well-known aperture size of zeolite 4A (3.8 Å) and 5A (4.3 Å). Interestingly, because of aperture flexibility, the studied C 4 hydrocarbon molecules that are larger than this effective aperture size still adsorb in the micropores of ZIF-8 with kinetic selectivities for iso-C 4H 8/iso-C 4H 10 of 180 and n-C 4H 10/iso-C 4H 10 of 2.5 × 10 6. These unexpected molecular sieving properties open up new opportunities for ZIF materials for separations that cannot be economically achieved by traditional microporous adsorbents such as synthetic zeolites. © 2012 American Chemical Society.

  15. Unconventional, highly selective CO2 adsorption in zeolite SSZ-13.

    Science.gov (United States)

    Hudson, Matthew R; Queen, Wendy L; Mason, Jarad A; Fickel, Dustin W; Lobo, Raul F; Brown, Craig M

    2012-02-01

    Low-pressure adsorption of carbon dioxide and nitrogen was studied in both acidic and copper-exchanged forms of SSZ-13, a zeolite containing an 8-ring window. Under ideal conditions for industrial separations of CO(2) from N(2), the ideal adsorbed solution theory selectivity is >70 in each compound. For low gas coverage, the isosteric heat of adsorption for CO(2) was found to be 33.1 and 34.0 kJ/mol for Cu- and H-SSZ-13, respectively. From in situ neutron powder diffraction measurements, we ascribe the CO(2) over N(2) selectivity to differences in binding sites for the two gases, where the primary CO(2) binding site is located in the center of the 8-membered-ring pore window. This CO(2) binding mode, which has important implications for use of zeolites in separations, has not been observed before and is rationalized and discussed relative to the high selectivity for CO(2) over N(2) in SSZ-13 and other zeolites containing 8-ring windows. © 2012 American Chemical Society

  16. Theoretical maximal storage of hydrogen in zeolitic frameworks.

    Science.gov (United States)

    Vitillo, Jenny G; Ricchiardi, Gabriele; Spoto, Giuseppe; Zecchina, Adriano

    2005-12-07

    Physisorption and encapsulation of molecular hydrogen in tailored microporous materials are two of the options for hydrogen storage. Among these materials, zeolites have been widely investigated. In these materials, the attained storage capacities vary widely with structure and composition, leading to the expectation that materials with improved binding sites, together with lighter frameworks, may represent efficient storage materials. In this work, we address the problem of the determination of the maximum amount of molecular hydrogen which could, in principle, be stored in a given zeolitic framework, as limited by the size, structure and flexibility of its pore system. To this end, the progressive filling with H2 of 12 purely siliceous models of common zeolite frameworks has been simulated by means of classical molecular mechanics. By monitoring the variation of cell parameters upon progressive filling of the pores, conclusions are drawn regarding the maximum storage capacity of each framework and, more generally, on framework flexibility. The flexible non-pentasils RHO, FAU, KFI, LTA and CHA display the highest maximal capacities, ranging between 2.86-2.65 mass%, well below the targets set for automotive applications but still in an interesting range. The predicted maximal storage capacities correlate well with experimental results obtained at low temperature. The technique is easily extendable to any other microporous structure, and it can provide a method for the screening of hypothetical new materials for hydrogen storage applications.

  17. Bioconjugated fluorescent zeolite L nanocrystals as labels in protein microarrays.

    Science.gov (United States)

    Li, Zhen; Luppi, Gianluigi; Geiger, Albert; Josel, Hans-Peter; De Cola, Luisa

    2011-11-18

    Zeolite L nanocrystals, as inorganic host material containing hydrophobic fluorophore N,N'-bis(2,6-dimethylphenyl)perylene-3,4,9,10-tetracarboxylic diimide in the unidirectional channels, are developed as new labels for biosensor systems. The external surface of the particles is modified with carboxylic acid groups for conjugation to primary amines of biomolecules such as antibodies. Anti-digoxigenin (anti-DIG) is selected to be immobilized on zeolite L via N-hydroxysulfosuccinimide ester linker. Together with DIG, it serves as a good universal binding pair for diverse analyte detection owing to the high binding affinity and low background noise. The conjugates are characterized by the dynamic light scattering technique for their hydrodynamic diameters and by enzyme-linked immunosorbent assay for antigen-antibody binding behavior. The characterizations prove that anti-DIG antibodies are successfully immobilized on zeolite L with their binding activities maintained. The microarray fluorescent sandwich immunoassay based on such nanocrystalline labels shows high sensitivity in a thyroid-stimulating hormone assay with the lower detection limit down to the femtomolar range. These new fluorescent labels possess great potential for in vitro diagnostics applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Molecular dynamics simulation of pervaporation in zeolite membranes

    Science.gov (United States)

    Jia, W.; Murad, S.

    The pervaporation separation of liquid mixtures of water/ethanol and water/methanol using three zeolite (Silicalite, NaA and Chabazite) membranes has been examined using the method of molecular dynamics. The main goal of this study was to identify intermolecular interactions between water, methanol, ethanol and the membrane surface that play a critical role in the separations. This would then allow better membranes to be designed more efficiently and systematically than the trial-and-error procedures often being used. Our simulations correctly exhibited all the qualitative experimental observations for these systems, including the hydrophobic or hydrophilic behaviour of zeolite membranes. The simulations showed that, for Silicalite zeolite, the separation is strongly influenced by the selective adsorption of ethanol. The separation factor, as a consequence, increases almost exponentially as the ethanol composition decreases. For ethanol dehydration in NaA and Chabazite, pore size was found to play a very important role in the separation; very high separation factors were therefore possible. Simulations were also used to investigate the effect of pore structure, feed compositions and operating conditions on the pervaporation efficiency. Finally, our simulations also demonstrated that molecular simulations could serve as a useful screening tool to determine the suitability of a membrane for potential pervaporation separation applications. Simulations can cost only a small fraction of an experiment, and can therefore be used to design experiments most likely to be successful.

  19. DESAIN EKSPERIMEN PENGARUH ZEOLIT TERHADAP PENURUNAN LIMBAH KADMIUM (Cd

    Directory of Open Access Journals (Sweden)

    Merry Siska

    2012-12-01

    Full Text Available Pencemaran lingkungan yang terjadi banyak disebabkan oleh limbah dari logam berat suatu industri, terutama industri pelapisan logam. Logam berat seperti kadmium (Cd merupakan limbah dari pelapisan logam yang memiliki efek negatif bagi makhluk hidup. Penelitian ini dilakukan untuk mengetahui pengaruh penggunaan zeolit dalam menurunkan kadar limbah kadmium (Cd dari proses pelapisan logam. Bahan kajian dalam penelitian ini adalah kemampuan zeolit dalam menurunkan limbah kadmium (Cd pada proses pelapisan logam. Penelitian ini menggunakan metode desain eksperimen rancangan acak lengkap untuk mengoptimalkan paduan parameter-parameter dan variabel yang ada dan hal yang berkaitan dengan penetapan baku mutu limbah agar dapat dibuang ke lingkungan. Setelah dilakukan eksperimen dan pengolahan data didapat nilai FHitung (0.22924 < F(Tabel, α, 0.05 (3.49 untuk tingkat kepercayaan 95% dan pada tingkat kepercayaan 99% FHitung (0.22924 < F(Tabel, α, 0.01 (5.95 maka hipotesis yang diajukan ditolak, sehingga hasil ini mengemukakan bahwa zeolit memberikan manfaat yang nyata terhadap penurunan kadar kadmium (Cd limbah pelapisan logam. Disarankan bagi perusahaan untuk mengatasi permasalahan yang terjadi dalam mengatasi limbah ini, harus ada penggunaan bahan alternatif yang dapat digunakan untuk mengatasi limbah kadmium agar dapat dibuang ke lingkungan dan sesuai ketetapan kementerian lingkungan hidup tanpa mengakibatkan polusi dan merusak ekosistem makhluk hidup lainnya.

  20. Development of Zeolite Nonwoven for the Adsorption of Radioactive Cesium - 13288

    Energy Technology Data Exchange (ETDEWEB)

    Murao, Ayako; Nakai, Tomonori; Mimura, Hitoshi [Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan); Miura, Teruo; Aoyama, Yoshihito [OJI KINOCLOTH K.K., 1-2-5 Iriyamase Fuji-shi, Shizuoka-ken 491-0204 (Japan)

    2013-07-01

    The zeolite nonwoven fabric produced by TDS (Totally Dry System) process has some advantages such as the control of zeolite content, flexibility, strength and water-resistant property depending on the purpose. Hence the zeolite nonwoven fabric is expected for the application in various fields of the decontamination of Cs-contaminated water. In this study, Cs adsorption properties of zeolite nonwoven fabrics were examined by batch experiments, and the radiation stability, thermal stability and chemical durability were evaluated. As for batch adsorption properties, relatively large uptake rate of Cs{sup +} was obtained; the uptake equilibrium attained within 20 min and the uptake (%) was above 95%. The differences in zeolite content had no effects on the Cs{sup +} uptake (%). The uptake (%) of Cs{sup +} in seawater was slightly lowered compared to that in the presence of HNO{sub 3}. The uptake (%) of Cs{sup +} in seawater was estimated to be above 90% after 2 h-shaking, indicating the considerable enhancement of uptake rate compared to the conventional granular zeolites. The uptake (%) of Cs{sup +} for the zeolite high content type was estimated to be above 99% by using {sup 137}Cs tracer. As for the comparison of sealing treatment, the uptake (%) for the zeolite sheet treated with edge sealing was larger than that with rapping treatment. The uptake (%) for the zeolite sheet (zeolite high content type) was estimated to be about 95%, which is independent of sealing treatment and NaOH concentration. As for the stability, the surface morphology and the structure of zeolite sheet were not altered by the treatment with acid and alkaline solutions under the experimental conditions. The zeolite sheets were also stable after {sup 60}Co-γ ray irradiation up to 7.01x10{sup 6} R. On the other hand, color change for both fiber and zeolite and the shrinkage of the fiber were observed after heat treatment at 150 deg. C for 2 h. Thus the considerable enhancement of adsorption