Controlled pilot oxidizer for a gas turbine combustor

Science.gov (United States)

Laster, Walter R.; Bandaru, Ramarao V.

2010-07-13

A combustor (22) for a gas turbine (10) includes a main burner oxidizer flow path (34) delivering a first portion (32) of an oxidizer flow (e.g., 16) to a main burner (28) of the combustor and a pilot oxidizer flow path (38) delivering a second portion (36) of the oxidizer flow to a pilot (30) of the combustor. The combustor also includes a flow controller (42) disposed in the pilot oxidizer flow path for controlling an amount of the second portion delivered to the pilot.

Metal-core@metal oxide-shell nanomaterials for gas-sensing applications: a review

Energy Technology Data Exchange (ETDEWEB)

Mirzaei, A.; Janghorban, K.; Hashemi, B. [Shiraz University, Department of Materials Science and Engineering (Iran, Islamic Republic of); Neri, G., E-mail: gneri@unime.it [University of Messina, Department of Electronic Engineering, Chemistry and Industrial Engineering (Italy)

2015-09-15

With an ever-increasing number of applications in many advanced fields, gas sensors are becoming indispensable devices in our daily life. Among different types of gas sensors, conductometric metal oxide semiconductor (MOS) gas sensors are found to be the most appealing for advanced applications in the automotive, biomedical, environmental, and safety sectors because of the their high sensitivity, reduced size, and low cost. To improve their sensing characteristics, new metal oxide-based nanostructures have thus been proposed in recent years as sensing materials. In this review, we extensively review gas-sensing properties of core@ shell nanocomposites in which metals as the core and metal oxides as the shell structure, both of nanometer sizes, are assembled into a single metal@metal oxide core–shell. These nanostructures not only combine the properties of both noble metals and metal oxides, but also bring unique synergetic functions in comparison with single-component materials. Up-dated achievements in the synthesis and characterization of metal@metal oxide core–shell nanostructures as well as their use in MOS sensors are here reported with the main objective of providing an overview about their gas-sensing properties.

Virtual gas. The TTF. Principles, judicial implications and the new Dutch Natural Gas Act

International Nuclear Information System (INIS)

Zafirova, Z.Z.

2009-01-01

Crucial legal and regulatory aspects of gas transactions taking place at virtual trading locations, in particular at the TTF (Title Transfer Facility) are described. The second section provides a factual description of the establishment and development of the TTF in the framework of the liberalization of the Dutch gas market and the products that are traded at the TTF. The third section elaborates on a number of legal issues in the framework of the contractual relations on a virtual hub (as the TTF). The fourth section discusses the role of the Bill for a New Gas Act. [nl

Effective enhancement of gas separation performance in mixed matrix membranes using core/shell structured multi-walled carbon nanotube/graphene oxide nanoribbons

Science.gov (United States)

Xue, Qingzhong; Pan, Xinglong; Li, Xiaofang; Zhang, Jianqiang; Guo, Qikai

2017-02-01

Novel core/shell structured multi-walled carbon nanotube/graphene oxide nanoribbons (MWCNT@GONRs) nanohybrids were successfully prepared using a modified chemical longitudinal unzipping method. Subsequently, the MWCNT@GONRs nanohybrids were used as fillers to enhance the gas separation performance of polyimide based mixed matrix membranes (MMMs). It is found that MMMs concurrently exhibited higher gas selectivity and higher gas permeability compared to pristine polyimide. The high gas selectivity could be attributed to the GONRs shell, which provided a selective barrier and large gas adsorbed area, while the high gas permeability resulted from the hollow structured MWCNTs core with smooth internal surface, which acted as a rapid transport channel. MWCNT@GONRs could be promising candidates to improve gas separation performance of MMMs due to the unique microstructures, ease of synthesis and low filling loading.

Advances in the Partial Oxidation of Methane to Synthesis Gas

Institute of Scientific and Technical Information of China (English)

Quanli Zhu; Xutao Zhao; Youquan Deng

2004-01-01

The conversion and utilization of natural gas is of significant meaning to the national economy,even to the everyday life of people. However, it has not become a popular industrial process as expected due to the technical obstacles. In the past decades, much investigation into the conversion of methane,predominant component of natural gas, has been carried out. Among the possible routes of methane conversion, the partial oxidation of methane to synthesis gas is considered as an effective and economically feasible one. In this article, a brief review of recent studies on the mechanism of the partial oxidation of methane to synthesis gas together with catalyst development is wherein presented.

Guidelines Gas Act. Information and Consultation Document 2001

International Nuclear Information System (INIS)

De Groene, P.; Teljeur, E.; Verdonkschot, I.R.

2001-06-01

This Information and Consultation Document has been drawn up for the consultation period that will be held prior to the approval of the new Guidelines, in accordance with sections 13 and 18 of the Dutch Gas Act. In determining the topics for discussion in the consultation document, DTe has based its decision on the scope and aim of these Guidelines. In doing so, DTe's objective is to achieve these aims in a responsible manner, with limited interventions in the market. The Guidelines focus firstly on gas transport companies, in so far as they transport gas to supply eligible customers. In the year 2002, customers with an annual off-take of 1 million m 3 or more will be eligible. Secondly, the Guidelines focus on gas storage companies that have a dominant position or are deemed to have a dominant position, in accordance with section 18(2) of the Gas Act. In determining the Guidelines, in accordance with section 13(1) of the Gas Act, the Director of DTe has to take into account the promotion of trade and the promotion of the efficient operation of gas transport companies and users of the gas network. In addition, it appears from the Parliamentary Proceedings that the Guidelines also have the aim of preventing abuse of a dominant position. This document indicates the way DTe intends to achieve the statutory aims referred to above. Partly on the basis of experience in other countries, DTe assumes that realising these aims and creating a 'level playing field' on the Dutch gas market is a gradual process that may take several years. It will not be possible to realise all the conditions for achieving the above-mentioned objectives, as outlined by DTe in the Information and Consultation Document, in 2002. DTe therefore intends to limit the Guidelines for the year 2002 to the conditions that have priority. The aim of the consultation process and the responses of the various markets players is partly to determine the conditions that have priority. For the purposes of

The influence of N-acetyl-L-cysteine on oxidative stress and nitric oxide synthesis in stimulated macrophages treated with a mustard gas analogue

Directory of Open Access Journals (Sweden)

Smith Milton

2008-06-01

Full Text Available Abstract Background Sulphur mustard gas, 2, 2'-dichlorodiethyl sulphide (HD, is a chemical warfare agent. Both mustard gas and its monofunctional analogue, 2-chloroethyl ethyl sulphide (CEES, are alkylating agents that react with and diminish cellular thiols and are highly toxic. Previously, we reported that lipopolysaccharide (LPS significantly enhances the cytotoxicity of CEES in murine RAW 264.7 macrophages and that CEES transiently inhibits nitric oxide (NO production via suppression of inducible NO synthase (iNOS protein expression. NO generation is an important factor in wound healing. In this paper, we explored the hypotheses that LPS increases CEES toxicity by increasing oxidative stress and that treatment with N-acetyl-L-cysteine (NAC would block LPS induced oxidative stress and protect against loss of NO production. NAC stimulates glutathione (GSH synthesis and also acts directly as a free radical scavenger. The potential therapeutic use of the antibiotic, polymyxin B, was also evaluated since it binds to LPS and could thereby block the enhancement of CEES toxicity by LPS and also inhibit the secondary infections characteristic of HD/CEES wounds. Results We found that 10 mM NAC, when administered simultaneously or prior to treatment with 500 μM CEES, increased the viability of LPS stimulated macrophages. Surprisingly, NAC failed to protect LPS stimulated macrophages from CEES induced loss of NO production. Macrophages treated with both LPS and CEES show increased oxidative stress parameters (cellular thiol depletion and increased protein carbonyl levels. NAC effectively protected RAW 264.7 cells simultaneously treated with CEES and LPS from GSH loss and oxidative stress. Polymyxin B was found to partially block nitric oxide production and diminish CEES toxicity in LPS-treated macrophages. Conclusion The present study shows that oxidative stress is an important mechanism contributing to CEES toxicity in LPS stimulated macrophages and

Effects of reaction temperature and inlet oxidizing gas flow rate on IG-110 graphite oxidation used in HTR-PM

International Nuclear Information System (INIS)

Sun Ximing; Dong Yujie; Zhou Yangping; Shi Lei; Sun Yuliang; Zhang Zuoyi; Li Zhengcao

2017-01-01

The oxidation behavior of a selected nuclear graphite (IG-110) used in Pebble-bed Module High Temperature gas-cooled Reactor was investigated under the condition of air ingress accident. The oblate rectangular specimen was oxidized by oxidant gas with oxygen mole fraction of 20% and flow rates of 125–500 ml/min at temperature of 400–1200°C. Experiment results indicate that the oxidation behavior can also be classified into three regimes according to temperature. The regime I at 400–550°C has lower apparent activation energies of 75.57–138.59 kJ/mol when the gas flow rate is 125–500 ml/min. In the regime II at 600–900°C, the oxidation rate restricted by the oxygen supply to graphite is almost stable with the increase of temperature. In the regime III above 900°C, the oxidation rate increases obviously with the increase of temperature.With the increase of inlet gas flow from 125 to 500 ml/min, the apparent activation energy in regime I is increased and the stableness of oxidation rate in regime II is reduced. (author)

Prospect of shale gas recovery enhancement by oxidation-induced rock burst

Directory of Open Access Journals (Sweden)

Lijun You

2017-11-01

Full Text Available By horizontal well multi-staged fracturing technology, shale rocks can be broken to form fracture networks via hydraulic force and increase the production rate of shale gas wells. Nonetheless, the fracturing stimulation effect may be offset by the water phase trapping damage caused by water retention. In this paper, a technique in transferring the negative factor of fracturing fluid retention into a positive factor of changing the gas existence state and facilitating shale cracking was discussed using the easy oxidation characteristics of organic matter, pyrite and other minerals in shale rocks. Furthermore, the prospect of this technique in tackling the challenges of large retention volume of hydraulic fracturing fluid in shale gas reservoirs, high reservoir damage risks, sharp production decline rate of gas wells and low gas recovery, was analyzed. The organic matter and pyrite in shale rocks can produce a large number of dissolved pores and seams to improve the gas deliverability of the matrix pore throats to the fracture systems. Meanwhile, in the oxidation process, released heat and increased pore pressure will make shale rock burst, inducing expansion and extension of shale micro-fractures, increasing the drainage area and shortening the gas flowing path in matrix, and ultimately, removing reservoir damage and improving gas recovery. To sum up, the technique discussed in the paper can be used to “break” shale rocks via hydraulic force and to “burst” shale rocks via chemical oxidation by adding oxidizing fluid to the hydraulic fracturing fluid. It can thus be concluded that this method can be a favorable supplementation for the conventional hydraulic fracturing of shale gas reservoirs. It has a broad application future in terms of reducing costs and increasing profits, maintaining plateau shale gas production and improving shale gas recovery.

18 CFR 380.12 - Environmental reports for Natural Gas Act applications.

Science.gov (United States)

2010-04-01

... effects of those hazards on the facility, and methods proposed to reduce the effects or risks. Resource... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Environmental reports... THE NATIONAL ENVIRONMENTAL POLICY ACT § 380.12 Environmental reports for Natural Gas Act applications...

Durable zinc oxide-containing sorbents for coal gas desulfurization

Science.gov (United States)

Siriwardane, Ranjani V.

1996-01-01

Durable zinc-oxide containing sorbent pellets for removing hydrogen sulfide from a gas stream at an elevated temperature are made up to contain titania as a diluent, high-surface-area silica gel, and a binder. These materials are mixed, moistened, and formed into pellets, which are then dried and calcined. The resulting pellets undergo repeated cycles of sulfidation and regeneration without loss of reactivity and without mechanical degradation. Regeneration of the pellets is carried out by contacting the bed with an oxidizing gas mixture.

18 CFR Appendix A to Part 380 - Minimum Filing Requirements for Environmental Reports Under the Natural Gas Act

Science.gov (United States)

2010-04-01

... Requirements for Environmental Reports Under the Natural Gas Act A Appendix A to Part 380 Conservation of Power... Filing Requirements for Environmental Reports Under the Natural Gas Act Environmental Reports Under the Natural Gas Act. Resource Report 1—General Project Description 1. Provide a detailed description and...

Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

Energy Technology Data Exchange (ETDEWEB)

Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

2011-07-01

Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

Partial oxidation process for producing a stream of hot purified gas

Science.gov (United States)

Leininger, T.F.; Robin, A.M.; Wolfenbarger, J.K.; Suggitt, R.M.

1995-03-28

A partial oxidation process is described for the production of a stream of hot clean gas substantially free from particulate matter, ammonia, alkali metal compounds, halides and sulfur-containing gas for use as synthesis gas, reducing gas, or fuel gas. A hydrocarbonaceous fuel comprising a solid carbonaceous fuel with or without liquid hydrocarbonaceous fuel or gaseous hydrocarbon fuel, wherein said hydrocarbonaceous fuel contains halides, alkali metal compounds, sulfur, nitrogen and inorganic ash containing components, is reacted in a gasifier by partial oxidation to produce a hot raw gas stream comprising H{sub 2}, CO, CO{sub 2}, H{sub 2}O, CH{sub 4}, NH{sub 3}, HCl, HF, H{sub 2}S, COS, N{sub 2}, Ar, particulate matter, vapor phase alkali metal compounds, and molten slag. The hot raw gas stream from the gasifier is split into two streams which are separately deslagged, cleaned and recombined. Ammonia in the gas mixture is catalytically disproportionated into N{sub 2} and H{sub 2}. The ammonia-free gas stream is then cooled and halides in the gas stream are reacted with a supplementary alkali metal compound to remove HCl and HF. Alkali metal halides, vaporized alkali metal compounds and residual fine particulate matter are removed from the gas stream by further cooling and filtering. The sulfur-containing gases in the process gas stream are then reacted at high temperature with a regenerable sulfur-reactive mixed metal oxide sulfur sorbent material to produce a sulfided sorbent material which is then separated from the hot clean purified gas stream having a temperature of at least 1000 F. 1 figure.

Catalysts for oxidation of mercury in flue gas

Science.gov (United States)

Granite, Evan J [Wexford, PA; Pennline, Henry W [Bethel Park, PA

2010-08-17

Two new classes of catalysts for the removal of heavy metal contaminants, especially mercury (Hg) from effluent gases. Both of these classes of catalysts are excellent absorbers of HCl and Cl.sub.2 present in effluent gases. This adsorption of oxidizing agents aids in the oxidation of heavy metal contaminants. The catalysts remove mercury by oxidizing the Hg into mercury (II) moieties. For one class of catalysts, the active component is selected from the group consisting of iridium (Ir) and iridum-platinum (Ir/Pt) alloys. The Ir and Ir/Pt alloy catalysts are especially corrosion resistant. For the other class of catalyst, the active component is partially combusted coal or "Thief" carbon impregnated with Cl.sub.2. Untreated Thief carbon catalyst can be self-activating in the presence of effluent gas streams. The Thief carbon catalyst is disposable by means of capture from the effluent gas stream in a particulate collection device (PCD).

75 FR 35632 - Transparency Provisions of Section 23 of the Natural Gas Act

Science.gov (United States)

2010-06-23

...; Order No. 704-C] Transparency Provisions of Section 23 of the Natural Gas Act Issued June 17, 2010... No. 552, under which natural gas market participants must annually report information regarding physical natural gas transactions that use an index or that contribute to or may contribute to the...

On the fission gas release from oxide fuels during normal grain growth

International Nuclear Information System (INIS)

Paraschiv, M.C.; Paraschiv, A.; Glodeanu, F.

1997-01-01

A mathematical formalism for calculating the fission gas release from oxide fuels considering an arbitrary distribution of fuel grain size with only zero boundary condition for gas diffusion at the grain boundary is proposed. It has also been proved that it becomes unnecessary to consider the grain volume distribution function for fission products diffusion when the grain boundary gas resolution is considered, if thermodynamic forces on grain boundaries are only time dependent. In order to highlight the effect of the normal grain growth on fission gas release from oxide fuels Hillert's and Lifshitz and Slyozov's theories have been selected. The last one was used to give an adequate treatment of normal grain growth for the diffusion-controlled grain boundary movement in oxide fuels. It has been shown that during the fuel irradiation, the asymptotic form of the grain volume distribution functions given by Hillert and Lifshitz and Slyozov models can be maintained but the grain growth rate constant becomes time dependent itself. Experimental results have been used to correlate the two theoretical models of normal grain growth to the fission gas release from oxide fuels. (orig.)

Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

Directory of Open Access Journals (Sweden)

M. Cihan Çakır

2016-09-01

Full Text Available Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption–dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors.

Science.gov (United States)

Çakır, M Cihan; Çalışkan, Deniz; Bütün, Bayram; Özbay, Ekmel

2016-09-29

Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO) heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption-dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

Flue gas cleanup using the Moving-Bed Copper Oxide Process

Energy Technology Data Exchange (ETDEWEB)

Pennline, Henry W; Hoffman, James S

2013-10-01

The use of copper oxide on a support had been envisioned as a gas cleanup technique to remove sulfur dioxide (SO{sub 2}) and nitric oxides (NO{sub x}) from flue gas produced by the combustion of coal for electric power generation. In general, dry, regenerable flue gas cleanup techniques that use a sorbent can have various advantages, such as simultaneous removal of pollutants, production of a salable by-product, and low costs when compared to commercially available wet scrubbing technology. Due to the temperature of reaction, the placement of the process into an advanced power system could actually increase the thermal efficiency of the plant. The Moving-Bed Copper Oxide Process is capable of simultaneously removing sulfur oxides and nitric oxides within the reactor system. In this regenerable sorbent technique, the use of the copper oxide sorbent was originally in a fluidized bed, but the more recent effort developed the use of the sorbent in a moving-bed reactor design. A pilot facility or life-cycle test system was constructed so that an integrated testing of the sorbent over absorption/regeneration cycles could be conducted. A parametric study of the total process was then performed where all process steps, including absorption and regeneration, were continuously operated and experimentally evaluated. The parametric effects, including absorption temperature, sorbent and gas residence times, inlet SO{sub 2} and NO{sub x} concentration, and flyash loadings, on removal efficiencies and overall operational performance were determined. Although some of the research results have not been previously published because of previous collaborative restrictions, a summary of these past findings is presented in this communication. Additionally, the potential use of the process for criteria pollutant removal in oxy-firing of fossil fuel for carbon sequestration purposes is discussed.

Study of non-stoichiometric BaSrTiFeO3 oxide dedicated to semiconductor gas sensors

International Nuclear Information System (INIS)

Fasquelle, D.; Verbrugghe, N.; Deputier, S.

2016-01-01

Developing instrumentation systems compatible with the European RoHS directive (restriction of hazardous substances) to monitor our environment is of great interest for our society. Our research therefore aims at developing innovating integrated systems of detection dedicated to the characterization of various environmental exposures. These systems, which integrate new gas sensors containing lead-free oxides, are dedicated to the detection of flammable and toxic gases. We have firstly chosen to study semiconductor gas sensors implemented with lead-free oxides in view to develop RoHS devices. Therefore thick films deposited by spin-coating and screen-printing have been chosen for their robustness, ease to realize and ease to finally obtain cost-effective sensors. As crystalline defects and ionic vacancies are of great interest for gas detection, we have decided to study a non-stoichiometric composition of the BaSrTiFeO 3 sensible oxide. Nonstoichiometric BaSrTiFeO 3 lead-free oxide thick films were deposited by screen-printing on polycrystalline AFO 3 substrates covered by a layer of Ag-Pd acting as bottom electrode. The physical characterizations have revealed a crystalline structure mainly composed of BaTiO 3 pseudo-cubic phase and Ba 4 Ti 12 O 27 monoclinic phase for the powder, and a porous microstructure for the thick films. When compared to a BSTF thick film with a stoichiometric composition, a notable increase in the BSTF dielectric constant value was observed when taking into account of a similar microstructure and grain size. The loss tangent mean value varies more softly for the non-stoichiometric BaSrTiFeO 3 films than for the perovskite BSTF film as tanδ decreases from 0.45 to 0.04 when the frequency increases from 100 Hz to 1 MHz. (paper)

Method for combined removal of mercury and nitrogen oxides from off-gas streams

Science.gov (United States)

Mendelsohn, Marshall H [Downers Grove, IL; Livengood, C David [Lockport, IL

2006-10-10

A method for removing elemental Hg and nitric oxide simultaneously from a gas stream is provided whereby the gas stream is reacted with gaseous chlorinated compound to convert the elemental mercury to soluble mercury compounds and the nitric oxide to nitrogen dioxide. The method works to remove either mercury or nitrogen oxide in the absence or presence of each other.

Oxidation-sulfidation behavior of Ni aluminide in oxygen-sulfur mixed-gas atmospheres

International Nuclear Information System (INIS)

Natesan, K.

1988-01-01

Oxidation-sulfidation studies were conducted with sheet samples of nickel aluminide, containing 23.5 at. % Al, 0.5 at. % Hf, and 0.2 at. % B, in an annealed condition and after preoxidation treatments. Continuous weight-change measurements were made by a thermogravimetric technique in exposure atmospheres of air, a low-pO/sub 2/ gas mixture, and low-pO/sub 2/ gas mixtures with several levels of sulfur. The air-exposed specimens developed predominantly nickel oxide; the specimen exposed to a low-pO/sub 2/ environment developed an aluminum oxide scale. As the sulfur content of the gas mixture increased, the alumina scale exhibited spallation and the alloy tended to form nickel sulfide as the reaction phase. The results indicated that the sulfidation reaction of nickel aluminide specimens (both bare and preoxidized) was determined by the rate of transport of nickel from the substrate through the scale to the gas/alumina scale interface, the mechanical integrity of the oxide scale, and the H/sub 2/S concentration in the exposure environment

Gas sensing behaviour of cerium oxide and magnesium aluminate

Indian Academy of Sciences (India)

Gas sensing behaviour of cerium oxide and magnesium aluminate composites ... A lone pairof the electron state was identified from the electro paramagnetic ... carbon monoxide (CO) (at 0.5, 1.0 and 1.5 bar) and ethanol (at 50 and 100 ppm) was ... The magnitude of the temperature varied linearly regardless of the gas ...

Zinc oxide hollow micro spheres and nano rods: Synthesis and applications in gas sensor

International Nuclear Information System (INIS)

Jamil, Saba; Janjua, Muhammad Ramzan Saeed Ashraf; Ahmad, Tauqeer; Mehmood, Tahir; Li, Songnan; Jing, Xiaoyan

2014-01-01

Zinc oxide nano rods and micro hollow spheres are successfully fabricated by adopting a simple solvo-thermal approach without employing any surfactant/template by keeping heating time as variable. The prepared products are characterized by using different instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to investigate the morphological dependence on the reaction time, analogous experiments with various reaction times are carried out. Depending upon heating time, different morphological forms have been identified such as hollow microsphere (4 μm to 5 μm) and nano rods with an average diameter of approximately 100 nm. The fabricated materials are also tested for ethanol gas sensor applications and zinc oxide hollow microsphere proven to be an efficient gas sensing materials. Nitrogen adsorption–desorption measurement was performed to understand better performance of zinc oxide micro hollow spheres as effective ethanol gas sensing material. - Graphical abstract: Graphical abstract is represented by zinc oxide sphere (prepared by simple solvothermal approach), its XRD pattern(characterization) and finally its application in gas sensing. - Highlights: • Zinc oxide spheres were prepared by using solvothermal method. • Detailed description of the morphology of microspheres assembled by nano rods. • Formation mechanism of zinc oxide spheres assembled by nano rods. • Zinc oxide spheres and nano rods displayed very good gas sensing ability

Low-temperature plasma-catalytic oxidation of formaldehyde in atmospheric pressure gas streams

International Nuclear Information System (INIS)

Ding Huixian; Zhu Aimin; Lu Fugong; Xu Yong; Zhang Jing; Yang Xuefeng

2006-01-01

Formaldehyde (HCHO) is a typical air pollutant capable of causing serious health disorders in human beings. This work reports plasma-catalytic oxidation of formaldehyde in gas streams via dielectric barrier discharges over Ag/CeO 2 pellets at atmospheric pressure and 70 0 C. With a feed gas mixture of 276 ppm HCHO, 21.0% O 2 , 1.0% H 2 O in N 2 , ∼99% of formaldehyde can be effectively destructed with an 86% oxidative conversion into CO 2 at GHSV of 16500 h -1 and input discharge energy density of 108 J l -1 . At the same experimental conditions, the conversion percentages of HCHO to CO 2 from pure plasma-induced oxidation (discharges over fused silica pellets) and from pure catalytic oxidation over Ag/CeO 2 (without discharges) are 6% and 33% only. The above results and the CO plasma-catalytic oxidation experiments imply that the plasma-generated short-lived gas phase radicals, such as O and HO 2 , play important roles in the catalytic redox circles of Ag/CeO 2 to oxidize HCHO and CO to CO 2

Reactor modeling and process analysis for partial oxidation of natural gas

NARCIS (Netherlands)

Albrecht, B.A.

2004-01-01

This thesis analyses a novel process of partial oxidation of natural gas and develops a numerical tool for the partial oxidation reactor modeling. The proposed process generates syngas in an integrated plant of a partial oxidation reactor, a syngas turbine and an air separation unit. This is called

Design of Highly Selective Gas Sensors via Physicochemical Modification of Oxide Nanowires: Overview

Directory of Open Access Journals (Sweden)

Hyung-Sik Woo

2016-09-01

Full Text Available Strategies for the enhancement of gas sensing properties, and specifically the improvement of gas selectivity of metal oxide semiconductor nanowire (NW networks grown by chemical vapor deposition and thermal evaporation, are reviewed. Highly crystalline NWs grown by vapor-phase routes have various advantages, and thus have been applied in the field of gas sensors over the years. In particular, n-type NWs such as SnO2, ZnO, and In2O3 are widely studied because of their simple synthetic preparation and high gas response. However, due to their usually high responses to C2H5OH and NO2, the selective detection of other harmful and toxic gases using oxide NWs remains a challenging issue. Various strategies—such as doping/loading of noble metals, decorating/doping of catalytic metal oxides, and the formation of core–shell structures—have been explored to enhance gas selectivity and sensitivity, and are discussed herein. Additional methods such as the transformation of n-type into p-type NWs and the formation of catalyst-doped hierarchical structures by branch growth have also proven to be promising for the enhancement of gas selectivity. Accordingly, the physicochemical modification of oxide NWs via various methods provides new strategies to achieve the selective detection of a specific gas, and after further investigations, this approach could pave a new way in the field of NW-based semiconductor-type gas sensors.

Gas generation over plutonium oxides in the 94-1 shelf-life surveillance program

International Nuclear Information System (INIS)

Berg, J.M.; Harradine, D.M.; Hill, D.D.; McFarlan, James T.; Padilla, D.D.; Prenger, F. Coyne; Veirs, D.K.; Worl, L.A.

2002-01-01

The Department of Energy (DOE) is embarking upon a program to store large quantities of plutonium-bearing materials for up to fifty years. The Los Alamos National Laboratory Shelf Life Project was established to bound the behavior of plutonium-bearing material meeting the DOE 3013 Standard. The shelf life study monitors temperature, pressure and gas composition over oxide materials in a limited number of large-scale 3013 inner containers and in many small-scale containers. For the large-scale study, baseline plutonium oxides, oxides exposed to high-humidity atmospheres, and oxides containing chloride salt impurities are planned. The first large-scale container represents a baseline and contains dry plutonium oxide prepared according to the 3013 Standard. This container has been observed for pressure, temperature and gas compositional changes for less than a year. Results indicate that no detectable changes in pressure and gas composition are observed.

Oxidation of ammonium sulfite by a multi-needle-to-plate gas phase pulsed corona discharge reactor

Science.gov (United States)

Ren, Hua; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

2013-03-01

The oxidation of ammonium sulfite in the ammonia-based flue gas desulfurization (FGD) process was investigated in a multi-needle-to-plate gas phase pulsed corona discharge reactor in this paper. The effect of several parameters, including capacitance and peak pulse voltage of discharge system, electrode gap and bubbling gas flow rate on the oxidation rate of ammonium sulfite was reviewed. The oxidation rate of ammonium sulfite could reach 47.2% at the capacitance, the peak pulse voltage, electrode gap and bubbling gas flow rate equal to 2 nF, -24.6 k V, 35 mm and 4 L min-1 within treatment time of 40 min The experimental results indicate that the gas phase pulsed discharge system with a multi-needle-to-plate electrode can oxide the ammonium sulfite. The oxidation rate increased with the applied capacitance and peak pulse voltage and decreased with the electrode gap. As the bubbling gas flow rate increased, the oxidation rate increased first and then tended to reach a stationary value. These results would be important for the process optimization of the (NH4)2SO3 to (NH4)2SO4 oxidation.

Sulfur-doped graphene via thermal exfoliation of graphite oxide in H2S, SO2, or CS2 gas.

Science.gov (United States)

Poh, Hwee Ling; Šimek, Petr; Sofer, Zdeněk; Pumera, Martin

2013-06-25

Doping of graphene with heteroatoms is an effective way to tailor its properties. Here we describe a simple and scalable method of doping graphene lattice with sulfur atoms during the thermal exfoliation process of graphite oxides. The graphite oxides were first prepared by Staudenmaier, Hofmann, and Hummers methods followed by treatments in hydrogen sulfide, sulfur dioxide, or carbon disulfide. The doped materials were characterized by scanning electron microscopy, high-resolution X-ray photoelectron spectroscopy, combustible elemental analysis, and Raman spectroscopy. The ζ-potential and conductivity of sulfur-doped graphenes were also investigated in this paper. It was found that the level of doping is more dramatically influenced by the type of graphite oxide used rather than the type of sulfur-containing gas used during exfoliation. Resulting sulfur-doped graphenes act as metal-free electrocatalysts for an oxygen reduction reaction.

Ultrafine particles and nitrogen oxides generated by gas and electric cooking

OpenAIRE

Dennekamp, M; Howarth, S; Dick, C; Cherrie, J; Donaldson, K; Seaton, A

2001-01-01

OBJECTIVES—To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.
METHODS—Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser. A TSI 3934 scanning mobility particle sizer was used to measure average nu...

Gas sensing properties of indium–gallium–zinc–oxide gas sensors in different light intensity

Directory of Open Access Journals (Sweden)

Kuen-Lin Chen

2015-06-01

Full Text Available We have successfully observed the change in indium–gallium–zinc–oxide (IGZO gas sensor sensitivity by controlling the light emitting diode (LED power under the same gas concentrations. The light intensity dependence of sensor properties is discussed. Different LED intensities obviously affected the gas sensor sensitivity, which decays with increasing LED intensity. High LED intensity decreases not only gas sensor sensitivity but also the response time (T90, response time constant (τres and the absorption rate per second. Low intensity irradiated to sensor causes high sensitivity, but it needs larger response time. Similar results were also observed in other kinds of materials such as TiO2. According to the results, the sensing properties of gas sensors can be modulated by controlling the light intensity.

Progress in the development of semiconducting metal oxide gas sensors: a review

International Nuclear Information System (INIS)

Moseley, Patrick T

2017-01-01

Since the first suggestion, during the 1950s, that high-surface-area metal oxides could be used as conductometric gas sensors enormous efforts have been made to enhance both the selectivity and the sensitivity of such devices, and to reduce their operational power requirements. This development has involved the exploration of response mechanisms, the selection of the most appropriate oxide compositions, the fabrication of two-phase ‘hetero-structures’, the addition of metallic catalyst particles and the optimisation of the manner in which the materials are presented to the gas—the structure and the nanostructure of the sensing elements. Far more of the scientific literature has been devoted to seeking such improvements in metal oxide gas sensors than has been directed at all other solid-state gas sensors together. Recent progress in the research and development of metal oxide gas sensor technology is surveyed in this invited review. The advances that have been made are quite spectacular and the results of individual pieces of work are drawn together here so that trends can be seen. Emerging features include: the significance of n-type/p-type switching, the enhancement of sensing performance of materials through the incorporation of secondary components and the advantages of interrogating sensors with alternating current rather than direct current. (topical review)

Microbial methane oxidation processes and technologies for mitigation of landfill gas emissions

DEFF Research Database (Denmark)

Scheutz, Charlotte; Kjeldsen, Peter; Bogner, J.E.

2009-01-01

Landfill gas containing methane is produced by anaerobic degradation of organic waste. Methane is a strong greenhouse gas and landfills are one of the major anthropogenic sources of atmospheric methane. Landfill methane may be oxidized by methanotrophic microorganisms in soils or waste materials...... to predict methane emissions from landfills. Additional research and technology development is needed before methane mitigation technologies utilizing microbial methane oxidation processes can become commercially viable and widely deployed....

Method and system for purification of gas streams for solid oxide cells

DEFF Research Database (Denmark)

2011-01-01

of: - providing at least one scrubber in the gas stream at the inlet side of the first electrode of the solid oxide cell; and/or providing at least one scrubber in the gas stream at the inlet side of the second electrode of the solid oxide cell; and - purifying the gas streams towards the first...... and second electrode; wherein the at least one scrubber in the gas stream at the inlet side of the first electrode and/or the at least one scrubber in the gas stream at the inlet side of the second electrode comprises a material suitable as an electrolyte material and a material suitable as an electrode...... material, and wherein the material suitable as an electrolyte material and a material suitable as an electrode material form triple phase boundaries similar to or identical to the triple phase boundaries of the electrode for which the gas stream is purified with the at least one scrubber....

Fission gas behavior in mixed-oxide fuel during transient overpower

International Nuclear Information System (INIS)

Randklev, E.H.; Treibs, H.A.; Mastel, B.; Baldwin, D.L.

1979-01-01

Fission gas behavior can be important in determining fuel pin and core performance during a reactor transient. The results are presented of examinations characterizing the changes in microstructural distribution and retention of fission gas in fuel for a series of transient overpower (50 cents/s) tested mixed-oxide fuel pins and their steady state siblings

Metal Oxides Doped PPY-PVA Blend Thin Films Based Gas Sensor

Directory of Open Access Journals (Sweden)

D. B. DUPARE

2009-02-01

Full Text Available Synthesis of metal oxides doped polypyrrole–polyvinyl alcohol blend thin films by in situ chemical oxidative polymerization, using microwave oven on glass substrate for development of Ammonia and Trimethyl ammine hazardous gas sensor. The all experimental process carried out at room temperature(304 K. These polymer materials were characterized by Chemical analyses, spectral studies (UV-visible and IR and conductivity measurement by four –probe technique. The surface morphology as observed in the SEM image was observed to be uniformly covering the entire substrate surface. The sensor was used for different concentration (ppm of TMA and Ammonia gas investigation at room temperature (304 k. This study found to possess improved electrical, mechanical and environmental stability metal oxides doped PPY-PVA films.

Monoterpene oxidation in an oxidative flow reactor: SOA yields and the relationship between bulk gas-phase properties and organic aerosol growth

Science.gov (United States)

Friedman, B.; Link, M.; Farmer, D.

2016-12-01

We use an oxidative flow reactor (OFR) to determine the secondary organic aerosol (SOA) yields of five monoterpenes (alpha-pinene, beta-pinene, limonene, sabinene, and terpinolene) at a range of OH exposures. These OH exposures correspond to aging timescales of a few hours to seven days. We further determine how SOA yields of beta-pinene and alpha-pinene vary as a function of seed particle type (organic vs. inorganic) and seed particle mass concentration. We hypothesize that the monoterpene structure largely accounts for the observed variance in SOA yields for the different monoterpenes. We also use high-resolution time-of-flight chemical ionization mass spectrometry to calculate the bulk gas-phase properties (O:C and H:C) of the monoterpene oxidation systems as a function of oxidant concentrations. Bulk gas-phase properties can be compared to the SOA yields to assess the capability of the precursor gas-phase species to inform the SOA yields of each monoterpene oxidation system. We find that the extent of oxygenated precursor gas-phase species corresponds to SOA yield.

Heavy haze in winter Beijing driven by fast gas phase oxidation

Science.gov (United States)

Lu, K.; Tan, Z.; Wang, H.; Li, X.; Wu, Z.; Chen, Q.; Wu, Y.; Ma, X.; Liu, Y.; Chen, X.; Shang, D.; Dong, H.; Zeng, L.; Shao, M.; Hu, M.; Fuchs, H.; Novelli, A.; Broch, S.; Hofzumahaus, A.; Holland, F.; Rohrer, F.; Bohn, B.; Georgios, G.; Schmitt, S. H.; Schlag, P.; Kiendler-Scharr, A.; Wahner, A.; Zhang, Y.

2017-12-01

Heavy haze conditions were frequently presented in the airsheds of Beijing and surrounding areas, especially during winter time. To explore the trace gas oxidation and the subsequent formation of aerosols, a comprehensive field campaign was performed at a regional site (in the campus of University of Chinese Academy of Science, UCAS) in Beijing winter 2016. Serious haze pollution processes were often observed with the fast increase of inorganic salt (especially nitrate) and these pollutions were always associated with enhanced humidity and the concentrations of PAN (PeroxyAcyl Nitrates) which is normally a marker of gas phase oxidations from NOx and VOCs. Moreover, based on the measurements of OH, HO2, RO2, total OH reactivity, N2O5, NO, NO2, SO2, particle concentrations/distributions/chemical compositions, and meteorological parameters, the gas phase oxidation rates that leads to the formation of sulfate, nitrate and secondary organic aerosols were estimated. These determined formation rates were clearly enhanced by several folds during pollution episodes compared to that of the clean air masses. Preliminary analysis result showed that the gas phase formation potential of nitrate and secondary organic aerosols were larger than the observed concentrations of nitrate and SOA of which the excess production may be explained by deposition and dilution.

KINETICS OF DIRECT OXIDATION OF H2S IN COAL GAS TO ELEMENTAL SULFUR; F

International Nuclear Information System (INIS)

K.C. Kwon

2002-01-01

Removal of hydrogen sulfide (H(sub 2)S) from coal gasifier gas and sulfur recovery are key steps in the development of Department of Energy's (DOE's) advanced Vision 21 plants that employ coal and natural gas and produce electric power and clean transportation fuels. These Vision 21 plants will require highly clean coal gas with H(sub 2)S below 1 ppm and negligible amounts of trace contaminants such as hydrogen chloride, ammonia, alkali, heavy metals, and particulate. The conventional method of sulfur removal and recovery employing amine, Claus, and tail-gas treatment is very expensive. A second generation approach developed under DOE's sponsorship employs hot-gas desulfurization (HGD) using regenerable metal oxide sorbents followed by Direct Sulfur Recovery Process (DSRP). However, this process sequence does not remove trace contaminants and is targeted primarily towards the development of advanced integrated gasification combined cycle (IGCC) plants that produce electricity (not both electricity and transportation fuels). There is an immediate as well as long-term need for the development of cleanup processes that produce highly clean coal gas for next generation Vision 21 plants. To this end, a novel process is now under development at Research Triangle Institute (RTI) in which the H(sub 2)S in coal gas is directly oxidized to elemental sulfur over a selective catalyst. Such a process is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H(sub 2)S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and HGD/DSRP. The objective of this research is to support the near- and long-term DOE efforts to commercialize this direct oxidation technology. Specifically, we aim to: Measure the kinetics of direct oxidation of H(sub 2)S to elemental sulfur over selective catalysts in the presence of major

Ethanol gas sensing performance of high-dimensional fuzz metal oxide nanostructure

Science.gov (United States)

Ibano, Kenzo; Kimura, Yoshihiro; Sugahara, Tohru; Lee, Heun Tae; Ueda, Yoshio

2018-04-01

Gas sensing ability of the He plasma induced fiber-like nanostructure, so-called fuzz structure, was firstly examined. A thin Mo layer deposited on a quartz surface was irradiated by He plasma to form the fuzz structure and oxidized by annealing in a quartz furnace. Electric conductivity of the fuzz Mo oxide layer was then measured through the Au electrodes deposited on the layer. Changes in electric conductivity by C2H5OH gas flow were examined as a function of temperature from 200 to 400 °C. Improved sensitivities were observed for the specimens after a fuzz nanostructure formation. However, the sensor developed in this study showed lower sensitivities than previously reported MoO3 nano-rod sensor, further optimization of oxidation is needed to improve the sensitivity.

Semiconducting oxide gas-sensitive resistors

International Nuclear Information System (INIS)

Dusastre, V.J.

1998-01-01

The overall aim of this thesis is to describe the gas sensing behaviour of a wide range of metal oxide semiconductors which exhibit tremendous changes in their electrical resistance at high temperatures (typically > 300 deg. C) upon exposure to traces (ppm) of reactive gases present in the air. The effects of surface segregation in antimony-doped tin dioxide (Sn 1-y Sb y O 2 ) on both the electrical response to water vapour and the catalytic combustion of methane in the presence of water vapour were demonstrated. Effects of microstructure, and especially particle size, on the behaviour (sensitivity and selectivity) of these compounds to carbon monoxide and methane were also demonstrated. A change in behaviour correlating with the Debye length was shown. Theoretical calculation methods were used to model surface segregation and surface defects. Antimony segregates as Sb 3+ and the complex (Sn(II).V o ) is a stable surface species. A model for gas response and surface reaction involving this complex is proposed. The properties of solid solution series prepared by systematic cation substitution as a way of understanding the gas response mechanism linked to the surface chemistry has been examined in (CrNbO 4 )x(Sn 1-y Sb y O 2 ) 1-x , Ti x (Sn 1-y Sb y ) 1-x O 2 , and (MWO 4 )x([Sn-Ti]O 2 ) 1x [with M: Mn, Fe, Co, Ni, Cu, Zn]. Effects of stoichiometry, microstructure, combustion gradient and surface segregation on gas (water, carbon monoxide, methane, propane and ammonia) sensitivity and selectivity have been observed and discussed. (author)

The Role of Post Flame Oxidation on the UHC Emission for Combustion of Natural Gas and Hydrogen Containing fuels

DEFF Research Database (Denmark)

Jensen, Torben Kvist; Schramm, Jesper

2003-01-01

In-cylinder post flame oxidation of unburned hydro-carbons from crevices in a lean burn spark ignition engine has been examined for natural gas and mixtures of natural gas and a hydrogen containing producer gas. For this purpose a model was developed to describe the mixing of cold unburned...... during in-cylinder post oxidation. The Arrhenius parameters were determined using the reaction mechanism, which gave the prediction of the results from the combustion reactor experiments. The investigation showed that addition of producer gas to natural gas promotes the in-cylinder post oxidation...... significantly. Furthermore it was found that the cyclic variation in the post oxidation is reduced by addition of producer gas to natural gas....

Improved zinc oxide film for gas sensor applications

Indian Academy of Sciences (India)

Zinc oxide (ZnO) is a versatile material for different commercial applications such as transparent electrodes, piezoelectric devices, varistors, SAW devices etc because of its high piezoelectric coupling, greater stability of its hexagonal phase and its pyroelectric property. In fact, ZnO is a potential material for gas sensor ...

Anodic ammonia oxidation to nitrogen gas catalyzed by mixed biofilms in bioelectrochemical systems

International Nuclear Information System (INIS)

Zhan, Guoqiang; Zhang, Lixia; Tao, Yong; Wang, Yujian; Zhu, Xiaoyu; Li, Daping

2014-01-01

In this paper we report ammonia oxidation to nitrogen gas using microbes as biocatalyst on the anode, with polarized electrode (+600 mV vs. Ag/AgCl) as electron acceptor. In batch experiments, the maximal rate of ammonia-N oxidation by the mixed culture was ∼ 60 mg L −1 d −1 , and nitrogen gas was the main products in anode compartment. Cyclic voltammetry for testing the electroactivity of the anodic biofilms revealed that an oxidation peak appeared at +600 mV (vs. Ag/AgCl), whereas the electrode without biofilms didn’t appear oxidation peak, indicating that the bioanode had good electroactivities for ammonia oxidation. Microbial community analysis of 16S rRNA genes based on high throughput sequencing indicated that the combination of the dominant genera of Nitrosomonas, Comamonas and Paracocus could be important for the electron transfer from ammonia oxidation to anode

AMMONIA REMOVAL AND NITROUS OXIDE PRODUCTION IN GAS-PHASE COMPOST BIOFILTERS

Science.gov (United States)

Biofiltration technology is widely utilized for treating ammonia gas (NH3), with one of its potential detrimental by-products being nitrous oxide (N2O), a greenhouse gas approximately 300 times more reactive to infrared than CO2. The present work intends to provide the relation between NH3 removal d...

Regeneration of iron oxide containing pellets used for hot gas clean up

Energy Technology Data Exchange (ETDEWEB)

Palmer, A.; Heeney, P.; Furimsky, E. (CANMET, Ottawa, Ontario (Canada). Energy Research Laboratories)

1989-09-01

Four iron-containing pelletized solids used for H{sub 2}S removal from hot gas were oxidized in a Cahn electrobalance and in a fixed bed reactor. The main reactions included the sequence in which FeS was oxidized to iron sulphate which then decomposed rapidly yielding SO{sub 2} and iron oxides. The oxidation occurred predominantly on the outer surface of the pellets. 12 refs., 5 figs., 5 tabs.

Nanocrystalline samarium oxide coated fiber optic gas sensor

International Nuclear Information System (INIS)

Renganathan, B.; Sastikumar, D.; Srinivasan, R.; Ganesan, A.R.

2014-01-01

Highlights: • This fiber optic gas sensor works at room temperature. • As-prepared and annealed Sm 2 O 3 nanoparticles are act as sensor materials. • Sm 2 O 3 clad modified fiber detect the ammonia, ethanol and methanol gases. • The response of evanescent wave loss has been studied for different concentrations. - Abstract: Nanocrystalline Sm 2 O 3 coated fiber optic sensor is proposed for detecting toxic gases such as ammonia, methanol and ethanol vapors. Sm 2 O 3 in the as prepared form as well as annealed form have been used as gas sensing materials, by making them as cladding of a PMMA fiber. The spectral characteristics of the Sm 2 O 3 gas sensor are presented for ammonia, methanol and ethanol gases with different concentrations ranging from 0 to 500 ppm. The sensor exhibits a linear variation in the output light intensity with the concentration. The enhanced gas sensitivity and selectivity of the sensor for ethanol is discussed briefly

Gas-phase advanced oxidation as an integrated air pollution control technique

Directory of Open Access Journals (Sweden)

Getachew A. Adnew

2016-03-01

Full Text Available Gas-phase advanced oxidation (GPAO is an emerging air cleaning technology based on the natural self-cleaning processes that occur in the Earth’s atmosphere. The technology uses ozone, UV-C lamps and water vapor to generate gas-phase hydroxyl radicals that initiate oxidation of a wide range of pollutants. In this study four types of GPAO systems are presented: a laboratory scale prototype, a shipping container prototype, a modular prototype, and commercial scale GPAO installations. The GPAO systems treat volatile organic compounds, reduced sulfur compounds, amines, ozone, nitrogen oxides, particles and odor. While the method covers a wide range of pollutants, effective treatment becomes difficult when temperature is outside the range of 0 to 80 °C, for anoxic gas streams and for pollution loads exceeding ca. 1000 ppm. Air residence time in the system and the rate of reaction of a given pollutant with hydroxyl radicals determine the removal efficiency of GPAO. For gas phase compounds and odors including VOCs (e.g. C6H6 and C3H8 and reduced sulfur compounds (e.g. H2S and CH3SH, removal efficiencies exceed 80%. The method is energy efficient relative to many established technologies and is applicable to pollutants emitted from diverse sources including food processing, foundries, water treatment, biofuel generation, and petrochemical industries.

Effects of oxygen gas pressure on properties of iron oxide films grown by pulsed laser deposition

International Nuclear Information System (INIS)

Guo, Qixin; Shi, Wangzhou; Liu, Feng; Arita, Makoto; Ikoma, Yoshifumi; Saito, Katsuhiko; Tanaka, Tooru; Nishio, Mitsuhiro

2013-01-01

Highlights: ► Pulsed laser deposition is a promising technique for growing iron oxide films. ► Crystal structure of the iron oxide films strongly depends on oxygen gas pressure. ► Optimum of the oxygen gas pressure leads single phase magnetite films with high crystal quality. -- Abstract: Iron oxide films were grown on sapphire substrates by pulsed laser deposition at oxygen gas pressures between 1 × 10 −5 and 1 × 10 −1 Pa with a substrate temperature of 600 °C. Atomic force microscope, X-ray diffraction, Raman spectroscopy, X-ray absorption fine structure, and vibrational sample magnetometer analysis revealed that surface morphology and crystal structure of the iron oxide films strongly depend on the oxygen gas pressure during the growth and the optimum oxygen gas pressure range is very narrow around 1 × 10 −3 Pa for obtaining single phase magnetite films with high crystal quality

Gas cleaning and hydrogen sulfide removal for COREX coal gas by sorption enhanced catalytic oxidation over recyclable activated carbon desulfurizer.

Science.gov (United States)

Sun, Tonghua; Shen, Yafei; Jia, Jinping

2014-02-18

This paper proposes a novel self-developed JTS-01 desulfurizer and JZC-80 alkaline adsorbent for H2S removal and gas cleaning of the COREX coal gas in small-scale and commercial desulfurizing devices. JTS-01 desulfurizer was loaded with metal oxide (i.e., ferric oxides) catalysts on the surface of activated carbons (AC), and the catalyst capacity was improved dramatically by means of ultrasonically assisted impregnation. Consequently, the sulfur saturation capacity and sulfur capacity breakthrough increased by 30.3% and 27.9%, respectively. The whole desulfurizing process combined selective adsorption with catalytic oxidation. Moreover, JZC-80 adsorbent can effectively remove impurities such as HCl, HF, HCN, and ash in the COREX coal gas, stabilizing the system pressure drop. The JTS-01 desulfurizer and JZC-80 adsorbent have been successfully applied for the COREX coal gas cleaning in the commercial plant at Baosteel, Shanghai. The sulfur capacity of JTS-01 desulfurizer can reach more than 50% in industrial applications. Compared with the conventional dry desulfurization process, the modified AC desulfurizers have more merit, especially in terms of the JTS-01 desulfurizer with higher sulfur capacity and low pressure drop. Thus, this sorption enhanced catalytic desulfurization has promising prospects for H2S removal and other gas cleaning.

Screen-printed Tin-doped indium oxide (ITO) films for NH3 gas sensing

International Nuclear Information System (INIS)

Mbarek, Hedia; Saadoun, Moncef; Bessais, Brahim

2006-01-01

Gas sensors using metal oxides have several advantageous features such as simplicity in device structure and low cost fabrication. In this work, Tin-doped indium oxide (ITO) films were prepared by the screen printing technique onto glass substrates. The granular and porous structure of screen-printed ITO are suitable for its use in gas sensing devices. The resistance of the ITO films was found to be strongly dependent on working temperatures and the nature and concentration of the ambient gases. We show that screen-printed ITO films have good sensing properties toward NH 3 vapours. The observed behaviors are explained basing on the oxidizing or the reducer nature of the gaseous species that react on the surface of the heated semi-conducting oxide

Studies on nitric oxide removal in simulated gas compositions under plasma-dielectric/catalytic discharges

International Nuclear Information System (INIS)

Rajanikanth, B.S.; Rout, Satyabrata

2001-01-01

Application of pulsed electrical discharges for gas cleaning is gaining prominence, mainly from the energy consideration point of view. This present paper presents recent work on applying the electrical discharge plasma technology for treating gaseous pollutants, in general, and nitric oxide, in particular, as this is one of the major contributors to air pollution. The present work focuses attention on pulsed electrical discharge technique for nitric oxide removal from simulated gas compositions and study of effect of packed dielectric pellets, with and without a coating of catalyst, on the removal process. Experiments were conducted in a cylindrical corona reactor energized by repetitive high voltage pulses. The effects of various parameters, viz. pulse voltage magnitude, pulse frequency, initial nitric oxide concentration and gas mixture composition on nitric oxide removal efficiency, are discussed. When the reactors were filled with different dielectric pellets like, barium titanate, alumina, and alumina coated with palladium catalyst, the improvement in nitric oxide removal efficiency is studied and discussed. The power dissipated in the reactor and the energy consumed per nitric oxide molecule removed was calculated. Further results and comparative study of various cases are presented in the paper

Nanostructured tin oxide films: Physical synthesis, characterization, and gas sensing properties.

Science.gov (United States)

Ingole, S M; Navale, S T; Navale, Y H; Bandgar, D K; Stadler, F J; Mane, R S; Ramgir, N S; Gupta, S K; Aswal, D K; Patil, V B

2017-05-01

Nanostructured tin oxide (SnO 2 ) films are synthesized using physical method i.e. thermal evaporation and are further characterized with X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy measurement techniques for confirming its structure and morphology. The chemiresistive properties of SnO 2 films are studied towards different oxidizing and reducing gases where these films have demonstrated considerable selectivity towards oxidizing nitrogen dioxide (NO 2 ) gas with a maximum response of 403% to 100ppm @200°C, and fast response and recovery times of 4s and 210s, respectively, than other test gases. In addition, SnO 2 films are enabling to detect as low as 1ppm NO 2 gas concentration @200°C with 23% response enhancement. Chemiresistive performances of SnO 2 films are carried out in the range of 1-100ppm and reported. Finally, plausible adsorption and desorption reaction mechanism of NO 2 gas molecules with SnO 2 film surface has been thoroughly discussed by means of an impedance spectroscopy analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

Minimising protein oxidation in retail-packed minced beef using three-gas MA-packaging

DEFF Research Database (Denmark)

Spanos, Dimitrios; Baussa Cano, Laura; Baron, Caroline P.

beef. To establish whether three-gas MAP (O2, CO2 and N2), instead of two-gas MAP (O2 and CO2), would affect sensory attributes, shelf life, protein and lipid oxidation, minced beef was packed in MAP with either 40%, 50% or 80% O2 and 20% or 40% CO2 with N2 as filler gas. When comparing traditional MA-packaging......Minced beef is usually packed in high oxygen modified atmosphere packaging (MAP) with a gas mixture consisting of 70-80% oxygen (O2) and 20-30% carbon dioxide (CO2). Unfortunately, this results in rubbery and less juicy beef patties with a more rancid flavour compared with fresh or nonoxygen packed...... (80% O2 + 20% CO2) with a low oxygen packaging atmosphere (40% O2 + 20% CO2 + 40% N2), the latter is seen to increase the meat oxidative stability during storage but decrease acceptability and shelf life. In contrast, high oxygen MAP (80% and 50% O2) results in more oxidation but a longer shelf life...

Sensing characteristics of nanocrystalline bismuth oxide clad-modified fiber optic gas sensor

Science.gov (United States)

Manjula, M.; Karthikeyan, B.; Sastikumar, D.

2017-08-01

Gas sensing properties of nanocrystalline bismuth oxide clad - modified fiber optic sensor is reported for ammonia, ethanol, methanol and acetone gasses at room temperature. The output of sensor increases or decreases for certain gasses when the concentration of the gas is increased. The sensor exhibits high response and good selectivity to methanol gas. Time response characteristics of the sensor are also reported.

Performance evaluation of non-thermal plasma injection for elemental mercury oxidation in a simulated flue gas

Energy Technology Data Exchange (ETDEWEB)

An, Jiutao; Shang, Kefeng; Lu, Na [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education of the People' s Republic of China, Dalian 116024 (China); Jiang, Yuze [Shandong Electric Power Research Institute, Jinan 250002 (China); Wang, Tiecheng [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education of the People' s Republic of China, Dalian 116024 (China); Li, Jie, E-mail: lijie@dlut.edu.cn [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education of the People' s Republic of China, Dalian 116024 (China); Wu, Yan [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education of the People' s Republic of China, Dalian 116024 (China)

2014-03-01

Graphical abstract: - Highlights: • The use of non-thermal plasma injection approach to oxidize Hg{sup 0} in simulated flue gas at 110 °C was studied. • A high Hg{sup 0} oxidation efficiency was observed in the mixed flue gas that included O{sub 2}, H{sub 2}O, SO{sub 2}, NO and HCl. • Chemical and physical processes (e.g., ozone, N{sub 2} metastable states and UV-light) contributed to Hg{sup 0} oxidation. • Mercury species mainly existed in the form of HgO(s) adhering to the suspended aerosols in the gas-phase. - Abstract: The use of non-thermal plasma (NTP) injection approach to oxidize elemental mercury (Hg{sup 0}) in simulated flue gas at 110 °C was studied, where a surface discharge plasma reactor (SDPR) inserted in the simulated flue duct was used to generate and inject active species into the flue gas. Approximately 81% of the Hg{sup 0} was oxidized and 20.5 μg kJ{sup −1} of energy yield was obtained at a rate of 3.9 J L{sup −1}. A maximal Hg{sup 0} oxidation efficiency was found with a change in the NTP injection air flow rate. A high Hg{sup 0} oxidation efficiency was observed in the mixed flue gas that included O{sub 2}, H{sub 2}O, SO{sub 2}, NO and HCl. Chemical and physical processes (e.g., ozone, N{sub 2} metastable states and UV-light) were found to contribute to Hg{sup 0} oxidation, with ozone playing a dominant role. The deposited mercury species on the internal surface of the flue duct was analyzed using X-ray photoelectron spectroscopy (XPS) and electronic probe microanalysis (EPMA), and the deposit was identified as HgO. The mercury species is thought to primarily exist in the form of HgO(s) by adhering to the suspended aerosols in the gas-phase.

Formation of oxides particles in ferritic steel by using gas-atomized powder

International Nuclear Information System (INIS)

Liu Yong; Fang Jinghua; Liu Donghua; Lu Zhi; Liu Feng; Chen Shiqi; Liu, C.T.

2010-01-01

Oxides dispersion strengthened (ODS) ferritic steel was prepared by using gas-atomized pre-alloyed powder, without the conventional mechanical alloying process. By adjusting the volume content of O 2 in the gas atmosphere Ar, the O level in the ferritic powder can be well controlled. The O dissolves uniformly in the ferritic powder, and a very thin layer of oxides forms on the powder surface. After hot deformation, the primary particle boundaries, which retain after sintering, can be disintegrated and near fully dense materials can be obtained. The oxide layer on the powder surface has a significant effect on the microstructural evolution. It may prevent the diffusion in between the primary particles during sintering, and may dissolve and/or induce the nucleation of new oxides in the ferritic matrix during recrystallization. Two kinds of oxide particles are found in the ferritic steel: large (∼100 nm) Ti-rich and fine (10-20 nm) Y-Ti-rich oxides. The hardness of the ferritic steel increases with increasing annealing temperatures, however, decreases at 1400 deg. C, due to the coarsening of precipitates and the recrystallization microstructure.

A Robust and Low-Complexity Gas Recognition Technique for On-Chip Tin-Oxide Gas Sensor Array

Directory of Open Access Journals (Sweden)

Farid Flitti

2008-01-01

Full Text Available Gas recognition is a new emerging research area with many civil, military, and industrial applications. The success of any gas recognition system depends on its computational complexity and its robustness. In this work, we propose a new low-complexity recognition method which is tested and successfully validated for tin-oxide gas sensor array chip. The recognition system is based on a vector angle similarity measure between the query gas and the representatives of the different gas classes. The latter are obtained using a clustering algorithm based on the same measure within the training data set. Experimented results on our in-house gas sensors array show more than 98% of correct recognition. The robustness of the proposed method is tested by recognizing gas measurements with simulated drift. Less than 1% of performance degradation is noted at the worst case scenario which represents a significant improvement when compared to the current state-of-the-art.

Formation of gas-phase π-allyl radicals from propylene over bismuth oxide and γ-bismuth molybdate catalysts

International Nuclear Information System (INIS)

Martir, W.; Lunsford, J.H.

1981-01-01

Gas-phase π-allyl radicals were produced when propylene reacted over Bi 2 O 3 and γ-bismuth molybdate catalysts at 723 K. The pressure in the catalyst zone was varied between 5 x 10 -3 and 1 torr. The radicals were detected by EPR spectroscopy together with a matrix isolation technique in which argon was used as the diluent. The matrix was formed on a sapphire rod at 12 K which was located 33-cm downstream from the catalyst. Bismuth oxide was more effective in the production of gas-phase allyl radicals than γ-bismuth molybdate. By contrast α-bismuth molybdate was ineffective in forming allyl radicals and MoO 3 acted as a sink for radicals which were produced elsewhere in the system. Comparison of the π-allyl radical and the stable product concentrations over Bi 2 O 3 revealed that gas-phase radical recombination reactions served as a major pathway for the formation of 1,5-hexadiene. Addition of small amounts of gas-phase oxygen increased the concentration of allyl radicals, and at greater oxygen levels allyl peroxy radicals were detected. Because of the effect of temperature on the equilibrium between allyl and allyl peroxy radicals, the latter product must be formed in the cooler part of the system

Effects of gas flow on oxidation reaction in liquid induced by He/O{sub 2} plasma-jet irradiation

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Atsushi; Uchida, Giichiro, E-mail: uchida@jwri.osaka-u.ac.jp; Takenaka, Kosuke; Setsuhara, Yuichi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Kawasaki, Toshiyuki [Department of Mechanical and Electrical Engineering, Nippon Bunri University, Oita, Oita 870-0397 (Japan); Koga, Kazunori; Sarinont, Thapanut; Amano, Takaaki; Shiratani, Masaharu [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Fukuoka 819-0395 (Japan)

2015-07-28

We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much faster gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface.

Gas Selectivity Control in Co3O4 Sensor via Concurrent Tuning of Gas Reforming and Gas Filtering using Nanoscale Hetero-Overlayer of Catalytic Oxides.

Science.gov (United States)

Jeong, Hyun-Mook; Jeong, Seong-Yong; Kim, Jae-Hyeok; Kim, Bo-Young; Kim, Jun-Sik; Abdel-Hady, Faissal; Wazzan, Abdulaziz A; Al-Turaif, Hamad Ali; Jang, Ho Won; Lee, Jong-Heun

2017-11-29

Co 3 O 4 sensors with a nanoscale TiO 2 or SnO 2 catalytic overlayer were prepared by screen-printing of Co 3 O 4 yolk-shell spheres and subsequent e-beam evaporation of TiO 2 and SnO 2 . The Co 3 O 4 sensors with 5 nm thick TiO 2 and SnO 2 overlayers showed high responses (resistance ratios) to 5 ppm xylene (14.5 and 28.8) and toluene (11.7 and 16.2) at 250 °C with negligible responses to interference gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co 3 O 4 sensor did not show remarkable selectivity toward any specific gas. The response and selectivity to methylbenzenes and ethanol could be systematically controlled by selecting the catalytic overlayer material, varying the overlayer thickness, and tuning the sensing temperature. The significant enhancement of the selectivity for xylene and toluene was attributed to the reforming of less reactive methylbenzenes into more reactive and smaller species and oxidative filtering of other interference gases, including ubiquitous ethanol. The concurrent control of the gas reforming and oxidative filtering processes using a nanoscale overlayer of catalytic oxides provides a new, general, and powerful tool for designing highly selective and sensitive oxide semiconductor gas sensors.

Effect of water injection on nitric oxide emissions of a gas turbine combustor burning natural gas fuel

Science.gov (United States)

Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

1973-01-01

The effect of direct water injection on the exhaust gas emissions of a turbojet combustor burning natural gas fuel was investigated. The results are compared with the results from similar tests using ASTM Jet-A fuel. Increasing water injection decreased the emissions of oxides of nitrogen (NOX) and increased the emissions of carbon monoxide and unburned hydrocarbons. The greatest percentage decrease in NOX with increasing water injection was at the lowest inlet-air temperature tested. The effect of increasing inlet-air temperature was to decrease the effect of the water injection. The reduction in NOX due to water injection was almost identical to the results obtained with Jet-A fuel. However, the emission indices of unburned hydrocarbons, carbon monoxide, and percentage nitric oxide in NOX were not.

Closed-cage tungsten oxide clusters in the gas phase.

Science.gov (United States)

Singh, D M David Jeba; Pradeep, T; Thirumoorthy, Krishnan; Balasubramanian, Krishnan

2010-05-06

During the course of a study on the clustering of W-Se and W-S mixtures in the gas phase using laser desorption ionization (LDI) mass spectrometry, we observed several anionic W-O clusters. Three distinct species, W(6)O(19)(-), W(13)O(29)(-), and W(14)O(32)(-), stand out as intense peaks in the regular mass spectral pattern of tungsten oxide clusters suggesting unusual stabilities for them. Moreover, these clusters do not fragment in the postsource decay analysis. While trying to understand the precursor material, which produced these clusters, we found the presence of nanoscale forms of tungsten oxide. The structure and thermodynamic parameters of tungsten clusters have been explored using relativistic quantum chemical methods. Our computed results of atomization energy are consistent with the observed LDI mass spectra. The computational results suggest that the clusters observed have closed-cage structure. These distinct W(13) and W(14) clusters were observed for the first time in the gas phase.

Electrospray-printed nanostructured graphene oxide gas sensors

Science.gov (United States)

Taylor, Anthony P.; Velásquez-García, Luis F.

2015-12-01

We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors’ response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%-60% relative humidity range while consuming recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ˜5 × 10-4 T) at ˜1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems.

Gas Generation from Actinide Oxide Materials

International Nuclear Information System (INIS)

Bailey, George; Bluhm, Elizabeth; Lyman, John; Mason, Richard; Paffett, Mark; Polansky, Gary; Roberson, G. D.; Sherman, Martin; Veirs, Kirk; Worl, Laura

2000-01-01

This document captures relevant work performed in support of stabilization, packaging, and long term storage of plutonium metals and oxides. It concentrates on the issue of gas generation with specific emphasis on gas pressure and composition. Even more specifically, it summarizes the basis for asserting that materials loaded into a 3013 container according to the requirements of the 3013 Standard (DOE-STD-3013-2000) cannot exceed the container design pressure within the time frames or environmental conditions of either storage or transportation. Presently, materials stabilized and packaged according to the 3013 Standard are to be transported in certified packages (the certification process for the 9975 and the SAFKEG has yet to be completed) that do not rely on the containment capabilities of the 3013 container. Even though no reliance is placed on that container, this document shows that it is highly likely that the containment function will be maintained not only in storage but also during transportation, including hypothetical accident conditions. Further, this document, by summarizing materials-related data on gas generation, can point those involved in preparing Safety Analysis Reports for Packages (SARPs) to additional information needed to assess the ability of the primary containment vessel to contain the contents and any reaction products that might reasonably be produced by the contents

Gas Generation from Actinide Oxide Materials

Energy Technology Data Exchange (ETDEWEB)

George Bailey; Elizabeth Bluhm; John Lyman; Richard Mason; Mark Paffett; Gary Polansky; G. D. Roberson; Martin Sherman; Kirk Veirs; Laura Worl

2000-12-01

This document captures relevant work performed in support of stabilization, packaging, and long term storage of plutonium metals and oxides. It concentrates on the issue of gas generation with specific emphasis on gas pressure and composition. Even more specifically, it summarizes the basis for asserting that materials loaded into a 3013 container according to the requirements of the 3013 Standard (DOE-STD-3013-2000) cannot exceed the container design pressure within the time frames or environmental conditions of either storage or transportation. Presently, materials stabilized and packaged according to the 3013 Standard are to be transported in certified packages (the certification process for the 9975 and the SAFKEG has yet to be completed) that do not rely on the containment capabilities of the 3013 container. Even though no reliance is placed on that container, this document shows that it is highly likely that the containment function will be maintained not only in storage but also during transportation, including hypothetical accident conditions. Further, this document, by summarizing materials-related data on gas generation, can point those involved in preparing Safety Analysis Reports for Packages (SARPs) to additional information needed to assess the ability of the primary containment vessel to contain the contents and any reaction products that might reasonably be produced by the contents.

Gas phase reactions of nitrogen oxides with olefins

Energy Technology Data Exchange (ETDEWEB)

Altshuller, A P; Cohen, I

1961-01-01

The nature of the condensation products formed in the gas phase reactions of nitrogen dioxide and nitric oxide with pentene-1, 2-methylbutene-2, and 2-methylbutadiene-1,3 was investigated. The reactants were combined at partial pressures in the range of 0.1 to 2.5 mm with the total pressure at one atmosphere. The products were determined by infrared and ultraviolet spectroscopy and colorimetry. The condensates included primary and secondary nitro compounds and alkyl nitrates. Strong hydroxyl and single bond carbon to oxygen stretching vibrations indicate the presence of either nitroalcohols or simple aliphatic alcohols formed through oxidation reactions. Carbonyl stretching frequencies observable in some of the reactions support the conclusion that a portion of the reactants disappear by oxidation rather than by nitration processes. The available results do not indicate the presence of appreciable amounts of tert.-nitro compounds, conjugated nitro-olefins, or gem-dinitro-alkanes. The reactivities of the olefins with the nitrogen oxides are in the decreasing order: 2-methyl-butadiene-1,3, 2-methylbutene-2, pentene-1. 20 references.

Comparison Between Conventional Design and Cathode Gas Recirculation Design of a Direct-Syngas Solid Oxide Fuel Cell–Gas Turbine Hybrid Systems Part I: Design Performance

Directory of Open Access Journals (Sweden)

Vahid Azami

2017-06-01

Keywords: Solid oxide fuel cell, Gas turbine, Cathode gas recirculation, Exergy. Article History: Received Feb 23rd 2017; Received in revised form May 26th 2017; Accepted June 1st 2017; Available online How to Cite This Article: Azami, V, and Yari, M. (2017 Comparison between conventional design and cathode gas recirculation design of a direct-syngas solid oxide fuel cell–gas turbine hybrid systems part I: Design performance. International Journal of Renewable Energy Develeopment, 6(2, 127-136. https://doi.org/10.14710/ijred.6.2.127-136

Intensification of oxidative desulfurization of gas oil by ultrasound irradiation: Optimization using Box–Behnken design (BBD)

International Nuclear Information System (INIS)

Jalali, Mohammad Reza; Sobati, Mohammad Amin

2017-01-01

Highlights: • Ultrasound-assisted oxidative desulfurization (UAOD) of gas oil was studied. • The influences of the different operating parameters were investigated. • Response surface methodology (RSM) was used to find the best operating parameters. • An accurate correlation was developed for the sulfur removal. • Ultrasound-assisted desulfurization process was compared with conventional process. - Abstract: In the present work, ultrasound assisted oxidative desulfurization (UAOD) of gas oil as the feedstock with sulfur content of 2210 ppmw was investigated using a mixture of hydrogen peroxide and formic acid as the oxidant and catalyst, respectively. The influences of main process variables such as sonication time (2–30 min), oxidation temperature (40–70 °C), hydrogen peroxide to sulfur molar ratio (10–50), formic acid to oxidant molar ratio (2–4), ultrasound power per gas oil volume (5.56–8.89 W/mL), and number of extraction stages (1–4) on the sulfur removal of gas oil were investigated. Response surface methodology (RSM) based on Box–Behnken design (BBD) and single-factor experiments were employed. The best performance of UAOD process for gas oil was achieved at 50 °C of reaction temperature, oxidant to sulfur molar ratio of 46.36, formic acid to oxidant molar ratio of 3.22, sonication time of 19.81 min, and 7.78 W/mL as the ultrasound power per gas oil volume. The sulfur removal of UAOD process was evaluated after oxidation under the abovementioned conditions followed by (a) one stage extraction and (b) four stages extraction using acetonitrile as solvent. The observed sulfur removal was 87 for case (a) and 96.2% for case (b). The UAOD process was also compared with conventional ODS process. Considerable improvement on the sulfur removal was observed specially in lower reaction time in the case of using ultrasound irradiation in comparison with conventional mixing.

Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

Directory of Open Access Journals (Sweden)

Anna Kachina

2007-01-01

Full Text Available Gas-phase photocatalytic oxidation (PCO and thermal catalytic oxidation (TCO of dimethylamine (DMA on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

Variation in excess oxidant factor in combustion products of MHD generator. [Natural gas fuel

Energy Technology Data Exchange (ETDEWEB)

Pinkhasik, M S; Mironov, V D; Zakharko, Yu A; Plavinskii, A I

1977-12-01

Methods and difficulties associated with determining the excess oxidant factor for natural gas-fired MHD generators are discussed. The measurement of this factor is noted to be essential for the optimization of the combustion chamber and operation of MHD generators. A gas analyzer of electrochemical type is considered as a quick - response sensor capable of analyzing the composition of the combustion products and thus determining accurately the excess oxidant factor. The principle of operation of this sensor is discussed and the dependence of the electrochemical sensor emf on excess oxidant factor is shown. Three types of sensors are illustrated and tables of test results are provided.

Graphene oxide for gas detection under standard humidity conditions

International Nuclear Information System (INIS)

Donarelli, Maurizio; Prezioso, Stefano; Perrozzi, Francesco; Ottaviano, Luca; Giancaterini, Luca; Cantalini, Carlo; Treossi, Emanuele; Palermo, Vincenzo; Santucci, Sandro

2015-01-01

Graphene oxide (GO) synthesis is the easiest way to functionalize graphene, preserving the high graphene surface to volume ratio. Therefore, GO is a promising candidate for gas sensing applications. In this paper, an easy-to-fabricate and high sensitivity GO-based gas sensor is proposed. The device is fabricated by drop-casting a solution of GO flakes dispersed in water on a prepatterned Si 3 N 4 substrate with 30 μm spaced Pt electrodes. The sensing material has been studied using scanning electron microscopy and x-ray photoelectron spectroscopy. The large lateral dimensions of the flakes (tens of microns) allow single GO flake to bridge adjacent electrodes. The high quality of the synthesized flakes results in the gas sensor high sensitivity to and low detection limit (20 ppb) of NO 2 . The gas sensor response to NO 2 has been studied in various relative humidity environments and it is demonstrated not to be affected by the presence of water vapor. Finally, the gas sensor responses to acetone, toluene, ethanol, and ammonia are reported. (paper)

Selective catalytic oxidation: a new catalytic approach to the desulfurization of natural gas and liquid petroleum gas for fuel cell reformer applications

Science.gov (United States)

Lampert, J.

In both natural gas and liquid petroleum gas (LPG), sulfur degrades the performance of the catalysts used in fuel reformers and fuel cells. In order to improve system performance, the sulfur must be removed to concentrations of less than 200 ppbv (in many applications to less than 20 ppbv) before the fuel reforming operation. Engelhard Corporation presents a unique approach to the desulfurization of natural gas and LPG. This new method catalytically converts the organic and inorganic sulfur species to sulfur oxides. The sulfur oxides are then adsorbed on a high capacity adsorbent. The sulfur compounds in the fuel are converted to sulfur oxides by combining the fuel with a small amount of air. The mixture is then heated from 250 to 270 °C, and contacted with a monolith supported sulfur tolerant catalyst at atmospheric pressure. When Engelhard Corporation demonstrated this catalytic approach in the laboratory, the result showed sulfur breakthrough to be less than 10 ppbv in the case of natural gas, and less than 150 ppbv for LPG. We used a simulated natural gas and LPG mixture, doped with a 50-170 ppmv sulfur compound containing equal concentrations of COS, ethylmercaptan, dimethylsulfide, methylethylsulfide and tetrahydrothiophene. There is no need for recycled H 2 as in the case for hydrodesulfurization.

Method for removing heavy metal and nitrogen oxides from flue gas, device for removing heavy metal and nitrogen oxides from flue gas

Energy Technology Data Exchange (ETDEWEB)

Huang, Hann-Sheng; Livengood, Charles David

1997-12-01

A method for the simultaneous removal of oxides and heavy metals from a fluid is provided comprising combining the fluid with compounds containing alkali and sulfur to create a mixture; spray drying the mixture to create a vapor phase and a solid phase; and isolating the vapor phase from the solid phase. A device is also provided comprising a means for spray-drying flue gas with alkali-sulfide containing liquor at a temperature sufficient to cause the flue gas to react with the compounds so as to create a gaseous fraction and a solid fraction and a means for directing the gaseous fraction to a fabric filter.

Conductometric gas sensors based on metal oxides modified with gold nanoparticles: a review

International Nuclear Information System (INIS)

Korotcenkov, Ghenadii; Cho, Beong K.; Brinzari, Vladimir

2016-01-01

This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required. (author)

Numerical modelling of methane oxidation efficiency and coupled water-gas-heat reactive transfer in a sloping landfill cover.

Science.gov (United States)

Feng, S; Ng, C W W; Leung, A K; Liu, H W

2017-10-01

Microbial aerobic methane oxidation in unsaturated landfill cover involves coupled water, gas and heat reactive transfer. The coupled process is complex and its influence on methane oxidation efficiency is not clear, especially in steep covers where spatial variations of water, gas and heat are significant. In this study, two-dimensional finite element numerical simulations were carried out to evaluate the performance of unsaturated sloping cover. The numerical model was calibrated using a set of flume model test data, and was then subsequently used for parametric study. A new method that considers transient changes of methane concentration during the estimation of the methane oxidation efficiency was proposed and compared against existing methods. It was found that a steeper cover had a lower oxidation efficiency due to enhanced downslope water flow, during which desaturation of soil promoted gas transport and hence landfill gas emission. This effect was magnified as the cover angle and landfill gas generation rate at the bottom of the cover increased. Assuming the steady-state methane concentration in a cover would result in a non-conservative overestimation of oxidation efficiency, especially when a steep cover was subjected to rainfall infiltration. By considering the transient methane concentration, the newly-modified method can give a more accurate oxidation efficiency. Copyright © 2017. Published by Elsevier Ltd.

Evaluation of the oxide and silicide fuels reactivity in the RSG-GAS core

International Nuclear Information System (INIS)

S, Tukiran; M S, Tagor; S, Lily; Pinem, S.

2000-01-01

Fuel exchange of The RSG-GAS reactor core from uranium oxide to uranium silicide in the same loading, density, and enrichment, that is, 250 gr, 2.98 gr/cm 3 , and 19.75 % respectively, will be performed in-step wise. In every cycle of exchange with 5/l mode, it is needed to evaluate the parameter of reactor core operation. One of the important operation parameters is fuel reactivity that gives effect to the core reactivity. The experiment was performed at core no. 36, BOC, low power which exist 2 silicide fuels. The evaluation was done based on the RSG-GAS control rod calibration consisting of 40 fuels and 8 control rod.s. From 40 fuels in the core, there are 2 silicide fuels, RI-225/A-9 and RI-224/C-3. For inserting 2 silicide fuels, the reactivity effect to the core must be know. To know this effect , it was performed fuels reactivity experiment, which based on control rod calibration. But in this case the RSG-GAS has no other fresh oxide fuel so that configuration of the RSG-GAS core was rearranged by taking out the both silicide fuels and this configuration is used as reference core. Then silicide fuel RI-224 was inserted to position F-3 replacing the fresh oxide fuel RI-260 so the different reactivity of the fuels is obtained. The experiment result showed that the fuel reactivity change is in amount of 12.85 cent (0.098 % ) The experiment result was compared to the calculation result, using IAFUEL code which amount to 13.49 cent (0.103 %) The result showed that the reactivity change of oxide to silicide fuel is small so that the fuel exchange from uranium oxide to uranium silicide in the first step can be done without any significant change of the operation parameter

Online Measurements of Highly Oxidized Organics in the Gas and Particle phase during SOAS and SENEX

Science.gov (United States)

Lopez-Hilfiker, F.; Lee, B. H.; Mohr, C.; Ehn, M.; Rubach, F.; Mentel, T. F.; Kleist, E.; Thornton, J. A.

2014-12-01

We present measurements of a large suite of gas and particle phase organic compounds made with a Filter Inlet for Gas and AEROsol (FIGAERO) coupled to a high resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington and with airborne HR-ToF-CIMS measurements. The FIGAERO instrument was deployed on the Jülich Plant Atmosphere Chamber to study α-pinene oxidation, and subsequently at the SMEAR II forest station in Hyytiälä, Finland and the SOAS ground site, in Brent Alabama. During the Southern Atmosphere Study, a gas-phase only version of the HR-ToF-CIMS was deployed on the NOAA WP-3 aircraft as part of SENEX. We focus here on highly oxygenated organic compounds derived from monoterpene oxidation detected both aloft during SENEX and at the ground-based site during SOAS. In both chamber and the atmosphere, many highly oxidized, low volatility compounds were observed in the gas and particles and many of the same compositions detected in the gas-phase were detected in the particles upon temperature programmed thermal desorption. The fraction of a given compound measured in the particle phase follows expected trends with elemental composition such as O/C ratios, but many compounds would not be well described by an absorptive partitioning model assuming unity activity coefficients. The detailed structure in the thermograms reveals a significant contribution from large molecular weight organics and/or oligomers in both chamber and ambient aerosol samples. Approximately 50% of the measured organics in the particle phase are associated with compounds having effective vapour pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. We discuss the implications of these findings for measurements of gas-particle partitioning and for evaluating the contribution of monoterpene oxidation to organic aerosol formation and growth. We also use the aircraft measurements and a

Performing in-situ chemical oxidation with Fenton's Reagent at a former gas work in Rotterdam

Energy Technology Data Exchange (ETDEWEB)

Plaisier, W.; Pancras, T. [In-situ Technieken BV, Wageningen (Netherlands); Bennen, M.; Bouwhuis, E. [Public Works Rotterdam (Netherlands)

2003-07-01

In-Situ Technieken BV is the first company in the Netherlands to apply full-scale in-situ chemical oxidation (ISCO) by means of Fenton's reagent or permanganates. The use of ISCO for soil remediation purposes originated in the USA. After three years of practical experience in the Netherlands it can be stated that ISCO has become a proven technology for source area treatment in the Netherlands as well. We present the results of a pilot ISCO treatment program with Fenton's reagent that was performed at the former gas works facility 'Feyenoord'. The site is one of the largest gas works facilities built in Rotterdam. The former gas production activities have lead to severe pollution of soil and groundwater over an area of approximately 3 hectares. Both laboratory and field observations showed that it would be very difficult to execute an efficient Fenton's reagent ISCO treatment program at this specific site for the following reasons. First of all, the contamination consisting of tar and tar-related compounds is found in an anthropogenic (man-made) soil of 9 meter in thickness. Secondly, high contents of carbonates and organic material were found in the soils, which act as a scavenger for the hydroxyl free radical in a Fenton's reagent ISCO system. The pilot test was performed in two phases with an intermediate period of 2 months. The injection of totally 24 tonnes hydrogen peroxide (50%) was anticipated. Reactions of the reagents in the soil were very strong. The presence of old (forgotten) boreholes and an intensive drainage system, in combination with the aggressive reaction resulted in short-circuiting of reagents to the surface. Out of the proposed 24 tonnes of hydrogen peroxide (50%) only 14.5 tonnes were injected. This would have effect on the amount of contamination oxidized. Nevertheless, the oxidation had a significant effect on the soil contamination. A reduction of approximately 90% for PAH was obtained. Reduction was also

Influence of fuel composition on the non-oxidizing heating of steel in a waste gas atmosphere

Energy Technology Data Exchange (ETDEWEB)

Minkler, W [LOI Industrieofenanlagen G.m.b.H., Essen (Germany, F.R.)

1979-04-01

On the basis of a number of graphs and data on theoretical combustion temperatures and the difference between the heating value of the fuel and the waste gas in respect of 1 m/sup 3/ of waste gas, the author demonstrates the influence of fuel composition on the non-oxidizing heating of steel in a waste gas atmosphere derived from five different fuels. A rotary-hearth furnace is described for the non-oxidizing heating of pressings from plain carbon and alloy steel.

How Pt nanoparticles affect TiO2-induced gas-phase photocatalytic oxidation reactions

NARCIS (Netherlands)

Fraters, B.D.; Amrollahi Buky, Rezvaneh; Mul, Guido

2015-01-01

The effect of Pt nanoparticles on the gas-phase photocatalytic oxidation activity of TiO2 is shown to be largely dependent on the molecular functionality of the substrate. We demonstrate that Pt nanoparticles decrease rates in photocatalytic oxidation of propane, whereas a strong beneficial effect

Treatment of reduced sulphur compounds and SO2 by Gas Phase Advanced Oxidation

DEFF Research Database (Denmark)

Meusinger, Carl; Bluhme, Anders Brostrøm; Ingemar, Jonas L.

2017-01-01

Reduced sulphur compounds (RSCs) emitted from pig farms are a major problem for agriculture, due to their health and environmental impacts and foul odour. This study investigates the removal of RSCs, including H2S, and their oxidation product SO2 using Gas Phase Advanced Oxidation (GPAO). GPAO...... is a novel air cleaning technique which utilises accelerated atmospheric chemistry to oxidise pollutants before removing their oxidation products as particles. Removal efficiencies of 24.5% and 3.9% were found for 461 ppb of H2S and 714 ppb of SO2 in a laboratory system (volumetric flow Q = 75 m3/h......). A numerical model of the reactor system was developed to explore the basic features of the system; its output was in fair agreement with the experiment. The model verified the role of OH radicals in initiating the oxidation chemistry. All sulphur removed from the gas phase was detected as particulate matter...

Electrospray-printed nanostructured graphene oxide gas sensors

International Nuclear Information System (INIS)

Taylor, Anthony P; Velásquez-García, Luis F

2015-01-01

We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors’ response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%–60% relative humidity range while consuming <6 μW. Devices with GO layers printed by different deposition recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ∼5 × 10"−"4 T) at ∼1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems. (paper)

Indium oxide octahedrons based on sol–gel process enhance room temperature gas sensing performance

Energy Technology Data Exchange (ETDEWEB)

Mu, Xiaohui [Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, Shandong (China); Chen, Changlong, E-mail: chem.chencl@hotmail.com [Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, Shandong (China); Han, Liuyuan [Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, Shandong (China); Shao, Baiqi [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Wei, Yuling [Instrumental Analysis Center, Qilu University of Technology, Jinan 250353, Shandong (China); Liu, Qinglong; Zhu, Peihua [Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, Shandong (China)

2015-07-15

Highlights: • In{sub 2}O{sub 3} octahedron films are prepared based on sol–gel technique for the first time. • The preparation possesses merits of low temperature, catalyst-free and large production. • It was found that the spin-coating process in film fabrication was key to achieve the octahedrons. • The In{sub 2}O{sub 3} octahedrons could significantly enhance room temperature NO{sub 2} gas sensing performance. - Abstract: Indium oxide octahedrons were prepared on glass substrates through a mild route based on sol–gel technique. The preparation possesses characteristics including low temperature, catalyst-free and large production, which is much distinguished from the chemical-vapor-deposition based methods that usually applied to prepare indium oxide octahedrons. Detailed characterization revealed that the indium oxide octahedrons were single crystalline, with {1 1 1} crystal facets exposed. It was found that the spin-coating technique was key for achieving the indium oxide crystals with octahedron morphology. The probable formation mechanism of the indium oxide octahedrons was proposed based on the experiment results. Room temperature NO{sub 2} gas sensing measurements exhibited that the indium oxide octahedrons could significantly enhance the sensing performance in comparison with the plate-like indium oxide particles that prepared from the dip-coated gel films, which was attributed to the abundant sharp edges and tips as well as the special {1 1 1} crystal facets exposed that the former possessed. Such a simple wet-chemical based method to prepare indium oxide octahedrons with large-scale production is promising to provide the advanced materials that can be applied in wide fields like gas sensing, solar energy conversion, field emission, and so on.

Indium oxide octahedrons based on sol–gel process enhance room temperature gas sensing performance

International Nuclear Information System (INIS)

Mu, Xiaohui; Chen, Changlong; Han, Liuyuan; Shao, Baiqi; Wei, Yuling; Liu, Qinglong; Zhu, Peihua

2015-01-01

Highlights: • In 2 O 3 octahedron films are prepared based on sol–gel technique for the first time. • The preparation possesses merits of low temperature, catalyst-free and large production. • It was found that the spin-coating process in film fabrication was key to achieve the octahedrons. • The In 2 O 3 octahedrons could significantly enhance room temperature NO 2 gas sensing performance. - Abstract: Indium oxide octahedrons were prepared on glass substrates through a mild route based on sol–gel technique. The preparation possesses characteristics including low temperature, catalyst-free and large production, which is much distinguished from the chemical-vapor-deposition based methods that usually applied to prepare indium oxide octahedrons. Detailed characterization revealed that the indium oxide octahedrons were single crystalline, with {1 1 1} crystal facets exposed. It was found that the spin-coating technique was key for achieving the indium oxide crystals with octahedron morphology. The probable formation mechanism of the indium oxide octahedrons was proposed based on the experiment results. Room temperature NO 2 gas sensing measurements exhibited that the indium oxide octahedrons could significantly enhance the sensing performance in comparison with the plate-like indium oxide particles that prepared from the dip-coated gel films, which was attributed to the abundant sharp edges and tips as well as the special {1 1 1} crystal facets exposed that the former possessed. Such a simple wet-chemical based method to prepare indium oxide octahedrons with large-scale production is promising to provide the advanced materials that can be applied in wide fields like gas sensing, solar energy conversion, field emission, and so on

Studies on Gas Sensing Performance of Pure and Surface Chrominated Indium Oxide Thick Film Resistors

Directory of Open Access Journals (Sweden)

D. N. CHAVAN

2010-12-01

Full Text Available The thick films of AR grade In2O3 were prepared by standard screen-printing technique. The gas sensing performance of thick film was tested for various gases. It showed maximum gas response to ethanol vapor at 350 oC for 80 ppm. To improve the gas response and selectivity of the film towards a particular gas, In2O3 thick films were modified by dipping them in an aqueous solution of 0.1 M CrO3 for different intervals of time. The surface chrominated (20 min In2O3 thick film showed maximum response to H2S gas (40 ppm than pure In2O3 thick film at 250 oC. Chromium oxide on the surface of the film shifts the gas response from ethanol vapor to H2S gas. A systematic study of sensing performance of the sensor indicates the key role played by chromium oxide on the surface of thick film. The selectivity, gas response and recovery time of the sensor were measured and presented.

Fission gas release from oxide fuels at high burnups (AWBA development program)

International Nuclear Information System (INIS)

Dollins, C.C.

1981-02-01

The steady state gas release, swelling and densification model previously developed for oxide fuels has been modified to accommodate the slow transients in temperature, temperature gradient, fission rate and pressure that are encountered in normal reactor operation. The gas release predictions made by the model were then compared to gas release data on LMFBR-EBRII fuels obtained by Dutt and Baker and reported by Meyer, Beyer, and Voglewede. Good agreement between the model and the data was found. A comparison between the model and three other sets of gas release data is also shown, again with good agreement

Gas Sensors Based on Tin Oxide Nanoparticles Synthesized from a Mini-Arc Plasma Source

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Ganhua Lu

2006-01-01

Full Text Available Miniaturized gas sensors or electronic noses to rapidly detect and differentiate trace amount of chemical agents are extremely attractive. In this paper, we report on the fabrication and characterization of a functional tin oxide nanoparticle gas sensor. Tin oxide nanoparticles are first synthesized using a convenient and low-cost mini-arc plasma source. The nanoparticle size distribution is measured online using a scanning electrical mobility spectrometer (SEMS. The product nanoparticles are analyzed ex-situ by high resolution transmission electron microscopy (HRTEM for morphology and defects, energy dispersive X-ray (EDX spectroscopy for elemental composition, electron diffraction for crystal structure, and X-ray photoelectron spectroscopy (XPS for surface composition. Nonagglomerated rutile tin oxide (SnO2 nanoparticles as small as a few nm have been produced. Larger particles bear a core-shell structure with a metallic core and an oxide shell. The nanoparticles are then assembled onto an e-beam lithographically patterned interdigitated electrode using electrostatic force to fabricate the gas sensor. The nanoparticle sensor exhibits a fast response and a good sensitivity when exposed to 100 ppm ethanol vapor in air.

The ideal oxygen/nitrous oxide fresh gas flow sequence with the Anesthesia Delivery Unit machine.

Science.gov (United States)

Hendrickx, Jan F A; Cardinael, Sara; Carette, Rik; Lemmens, Hendrikus J M; De Wolf, Andre M

2007-06-01

To determine whether early reduction of oxygen and nitrous oxide fresh gas flow from 6 L/min to 0.7 L/min could be accomplished while maintaining end-expired nitrous oxide concentration > or =50% with an Anesthesia Delivery Unit anesthesia machine. Prospective, randomized clinical study. Large teaching hospital in Belgium. 53 ASA physical status I and II patients requiring general endotracheal anesthesia and controlled mechanical ventilation. Patients were randomly assigned to one of 4 groups depending on the duration of high oxygen/nitrous oxide fresh gas flow (two and 4 L/min, respectively) before lowering total fresh gas flow to 0.7 L/min (0.3 and 0.4 L/min oxygen and nitrous oxide, respectively): one, two, three, or 5 minutes (1-minute group, 2-minute group, 3-minute group, and 5-minute group), with n = 10, 12, 13, and 8, respectively. The course of the end-expired nitrous oxide concentration and bellows volume deficit at end-expiration was compared among the 4 groups during the first 30 minutes. At the end of the high-flow period the end-expired nitrous oxide concentration was 35.6 +/- 6.2%, 48.4 +/- 4.8%, 53.7 +/- 8.7%, and 57.3 +/- 1.6% in the 4 groups, respectively. Thereafter, the end-expired nitrous oxide concentration decreased to a nadir of 36.1 +/- 4.5%, 45.4 +/- 3.8%, 50.9 +/- 6.1%, and 55.4 +/- 2.8% after three, 4, 6, and 8 minutes after flows were lowered in the 1- to 5-minute groups, respectively. A decrease in bellows volume was observed in most patients, but was most pronounced in the 2-minute group. The bellows volume deficit gradually faded within 15 to 20 minutes in all 4 groups. A 3-minute high-flow period (oxygen and nitrous oxide fresh gas flow of 2 and 4 L/min, respectively) suffices to attain and maintain end-expired nitrous oxide concentration > or =50% and ensures an adequate bellows volume during the ensuing low-flow period.

Nitric oxide coordinates metabolism, growth, and development via the nuclear receptor E75

OpenAIRE

Cáceres, Lucía; Necakov, Aleksandar S.; Schwartz, Carol; Kimber, Sandra; Roberts, Ian J.H.; Krause, Henry M.

2011-01-01

Nitric oxide gas acts as a short-range signaling molecule in a vast array of important physiological processes, many of which include major changes in gene expression. How these genomic responses are induced, however, is poorly understood. Here, using genetic and chemical manipulations, we show that nitric oxide is produced in the Drosophila prothoracic gland, where it acts via the nuclear receptor ecdysone-induced protein 75 (E75), reversing its ability to interfere with its heterodimer part...

Enhancement of methane gas sensing characteristics of graphene oxide sensor by heat treatment and laser irradiation.

Science.gov (United States)

Assar, Mohammadreza; Karimzadeh, Rouhollah

2016-12-01

The present study uses a rapid, easy and practical method for cost-effective fabrication of a methane gas sensor. The sensor was made by drop-casting a graphene oxide suspension onto an interdigital circuit surface. The electrical conductivity and gas-sensing characteristics of the sensor were determined and then heat treatment and in situ laser irradiation were applied to improve the device conductivity and gas sensitivity. Real-time monitoring of the evolution of the device current as a function of heat treatment time revealed significant changes in the conductance of the graphene oxide sensor. The use of low power laser irradiation enhanced both the electrical conductivity and sensing response of the graphene oxide sensor. Copyright © 2016 Elsevier Inc. All rights reserved.

Tungsten Oxide Photonic Crystals as Optical Transducer for Gas Sensing.

Science.gov (United States)

Amrehn, Sabrina; Wu, Xia; Wagner, Thorsten

2018-01-26

Some metal oxide semiconductors, such as tungsten trioxide or tin dioxide, are well-known as resistive transducers for gas sensing and offer high sensitivities down to the part per billion level. Electrical signal read-out, however, limits the information obtained on the electronic properties of metal oxides to a certain frequency range and its application because of the required electrical contacts. Therefore, a novel approach for building an optical transducer for gas reactions utilizing metal oxide photonic crystals is presented here. By the rational design of the structure and composition it is possible to synthesize a functional material which allows one to obtain insight into its electronic properties in the optical frequency range with simple experimental measures. The concept is demonstrated by tungsten trioxide inverse opal structure as optical transducer material for hydrogen sensing. The sensing behavior is analyzed in a temperature range from room temperature to 500 °C and in a wide hydrogen concentration range (3000 ppm to 10%). The sensing mechanism is mainly the refractive index change resulting from hydrogen intercalation in tungsten trioxide, but the back reaction has also impact on the optical properties of this system. Detailed chemical reaction studies provide suggestions for specific sensing conditions.

Spectroscopic and electrical sensing mechanism in oxidant-mediated polypyrrole nanofibers/nanoparticles for ammonia gas

International Nuclear Information System (INIS)

Ishpal; Kaur, Amarjeet

2013-01-01

Ammonia gas sensing mechanism in oxidant-mediated polypyrrole (PPy) nanofibers/nanoparticles has been studied through spectroscopic and electrical investigations. PPy nanofibers/nanoparticles have been synthesized by chemical oxidation method in the presence of various oxidizing agents such as ammonium persulfate (APS), potassium persulfate (PPS), vanadium pentoxide (V 2 O 5 ), and iron chloride (FeCl 3 ). Scanning electron microscopy study revealed that PPy nanofibers of about 63, 71 and 79 nm diameters were formed in the presence of APS, PPS, V 2 O 5 , respectively, while PPy nanoparticles of about 100–110 nm size were obtained in the presence of FeCl 3 as an oxidant. The structural investigations and confirmation of synthesis of PPy were established through Fourier transform infrared and Raman spectroscopy. The gas sensing behavior of the prepared PPy samples is investigated by measuring the electrical resistance in ammonia environment. The observed gas sensing response (ΔR/Rx100) at 100 ppm level of ammonia is ∼4.5 and 18 % for the samples prepared with oxidizing agents FeCl 3 and APS, respectively, and by changing the ammonia level from 50 to 300 ppm, the sensing response varies from ∼4.5 to 11 % and ∼10 to 39 %, respectively. Out of all four samples, the PPy nanofibers prepared in the presence of APS have shown the best sensing response. The mechanism of gas sensing response of the PPy samples has been investigated through Raman spectroscopy study. The decrease of charge carrier concentration through reduction of polymeric chains has been recognized through Raman spectroscopic measurements recorded in ammonia environment.

Studies on Gas Sensing Performance of Cr-doped Indium Oxide Thick Film Sensors

Directory of Open Access Journals (Sweden)

D. N. Chavan

2011-02-01

Full Text Available A series of In1-xCrxO3 composites, with x ranging from 0.01 to 0.5wt% were prepared by mechanochemically starting from InCl3 and CrO3. Structural and micro structural characteristics of the sample were investigated by XRD, SEM with EDAX. Thick films of pure Indium Oxide and composites were prepared by standard screen printing technique. The gas sensitivity of these thick films was tested for various gases. The pure Indium Oxide thick film (x=0 shows maximum sensitivity to ethanol vapour (80 ppm at 350 oC, but composite-A (x=0.01 thick film shows maximum sensitivity to H2S gas (40 ppm at 250 oC, composite-B (x=0.1 thick film shows higher sensitivity to NH3 gas (80 ppm at 250 oC and composite-C (x=0.5 thick film shows maximum sensitivity to Cl2 gas (80 ppm at 350 oC. A systematic study of gas sensing performance of the sensors indicates the key role played by concentration variation of Cr doped species. The sensitivity, selectivity and recovery time of the sensor were measured and presented.

Ethylene Gas Sensing Properties of Tin Oxide Nanowires Synthesized via CVD Method

Science.gov (United States)

Akhir, Maisara A. M.; Mohamed, Khairudin; Rezan, Sheikh A.; Arafat, M. M.; Haseeb, A. S. M. A.; Uda, M. N. A.; Nuradibah, M. A.

2018-03-01

This paper studies ethylene gas sensing performance of tin oxide (SnO2) nanowires (NWs) as sensing material synthesized using chemical vapor deposition (CVD) technique. The effect of NWs diameter on ethylene gas sensing characteristics were investigated. SnO2 NWs with diameter of ∼40 and ∼240 nm were deposited onto the alumina substrate with printed gold electrodes and tested for sensing characteristic toward ethylene gas. From the finding, the smallest diameter of NWs (42 nm) exhibit fast response and recovery time and higher sensitivity compared to largest diameter of NWs (∼240 nm). Both sensor show good reversibility features for ethylene gas sensor.

Zinc oxide nanostructured layers for gas sensing applications

Science.gov (United States)

Caricato, A. P.; Cretí, A.; Luches, A.; Lomascolo, M.; Martino, M.; Rella, R.; Valerini, D.

2011-03-01

Various kinds of zinc oxide (ZnO) nanostructures, such as columns, pencils, hexagonal pyramids, hexagonal hierarchical structures, as well as smooth and rough films, were grown by pulsed laser deposition using KrF and ArF excimer lasers, without use of any catalyst. ZnO films were deposited at substrate temperatures from 500 to 700°C and oxygen background pressures of 1, 5, 50, and 100 Pa. Quite different morphologies of the deposited films were observed using scanning electron microscopy when different laser wavelengths (248 or 193 nm) were used to ablate the bulk ZnO target. Photoluminescence studies were performed at different temperatures (down to 7 K). The gas sensing properties of the different nanostructures were tested against low concentrations of NO2. The variation in the photoluminescence emission of the films when exposed to NO2 was used as transduction mechanism to reveal the presence of the gas. The nanostructured films with higher surface-to-volume ratio and higher total surface available for gas adsorption presented higher responses, detecting NO2 concentrations down to 3 ppm at room temperature.

Effect of Annealing on Tungsten Oxide Thin Films for Acetone Gas ...

Indian Academy of Sciences (India)

11

Abstract: The gas sensing properties and topology of tungsten oxide thin films ..... Figure 3: Atomic force microscopy images of sensing film for (a) as-deposited (a) .... the surface, it forms compounds with the oxygen ions species present on the ...

A conceptual and calculational model for gas formation from impure calcined plutonium oxides

International Nuclear Information System (INIS)

Lyman, John L.; Eller, P. Gary

2000-01-01

Safe transport and storage of pure and impure plutonium oxides requires an understanding of processes that may generate or consume gases in a confined storage vessel. We have formulated conceptual and calculational models for gas formation from calcined materials. The conceptual model for impure calcined plutonium oxides is based on the data collected to date

Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide.

Science.gov (United States)

Hirai, Kenji; Isobe, Shigehito; Sada, Kazuki

2015-12-18

Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants.

The gas phase oxide and oxyhydroxide chemistry of trace amounts of rhenium

International Nuclear Information System (INIS)

Eichler, R.; Eichler, B.; Jost, D.T.; Dressler, R.; Tuerler, A.; Gaeggeler, H.W.

1999-01-01

In preparation of experiments to investigate the chemical properties of bohrium (Bh, element 107) the behaviour of Re, its lighter homologue in group 7, was studied in different oxidizing chemical systems. The adsorption data of Re oxide and oxyhydroxide compounds on quartz surfaces were evaluated from results of thermochromatography experiments and confirmed in isothermal gas chromatography experiments applying 1 cm as standard state for the simple gas adsorption process: X(g) ↔ X(ads) (X = ReO 3 , HReO 4 ) ΔH ads (ReO 3 ) = -190 ± 10 kJ/mol; ΔS ads (ReO 3 ) = -179±30 J/mol K; ΔH ads (HReO 4 ) = -77 ± 5 kJ/mol; ΔS ads (HReO 4 ) = -187±50 J/mol K. An on-line separation method for oxides and oxyhydroxides of short lived Re isotopes using isothermal high temperature gas-solid adsorption chromatography was developed. Separation yields and times of group 7 elements from lanthanides (model for actinides), polonium and bismuth were determined using the model isotopes 169,170,174,176 Re, 152-155 Er, 151-154 Ho, 218 Po, and 214 Bi. An updated correlation function between the microscopic adsorption enthalpy and the macroscopic sublimation enthalpy was calculated from the experimental adsorption data of this work and literature data. (orig.)

CdO Doped Indium Oxide Thick Film as a Low Temperature H2S Gas Sensor

Directory of Open Access Journals (Sweden)

D. N. CHAVAN

2011-06-01

Full Text Available The thick films of AR grade In2O3 were prepared by standard screen-printing technique. The gas sensing performance of thick film was tested for various gases. It showed maximum gas response to ethanol vapor at 350 oC for 80 ppm. To improve the gas response and selectivity of the film towards a particular gas, In2O3 thick films were modified by dipping them in an aqueous solution of 0.1 M CdCl2 for different intervals of time. The surface modified (10 min In2O3 thick film showed maximum response to H2S gas (10 ppm than pure In2O3 thick film at 150 oC. Cadmium oxide on the surface of the film shifts the gas response from ethanol vapor to H2S gas. A systematic study of sensing performance of the thick films indicates the key role played by cadmium oxide on the surface of thick films. The selectivity, gas response and recovery time of the thick films were measured and presented.

Nitrogen gas plasma treatment of bacterial spores induces oxidative stress that damages the genomic DNA.

Science.gov (United States)

Sakudo, Akikazu; Toyokawa, Yoichi; Nakamura, Tetsuji; Yagyu, Yoshihito; Imanishi, Yuichiro

2017-01-01

Gas plasma, produced by a short high‑voltage pulse generated from a static induction thyristor power supply [1.5 kilo pulse/sec (kpps)], was demonstrated to inactivate Geobacillus stearothermophilus spores (decimal reduction time at 15 min, 2.48 min). Quantitative polymerase chain reaction and enzyme‑linked immunosorbent assays further indicated that nitrogen gas plasma treatment for 15 min decreased the level of intact genomic DNA and increased the level of 8-hydroxy-2'-deoxyguanosine, a major product of DNA oxidation. Three potential inactivation factors were generated during operation of the gas plasma instrument: Heat, longwave ultraviolet-A and oxidative stress (production of hydrogen peroxide, nitrite and nitrate). Treatment of the spores with hydrogen peroxide (3x2‑4%) effectively inactivated the bacteria, whereas heat treatment (100˚C), exposure to UV-A (75‑142 mJ/cm2) and 4.92 mM peroxynitrite (•ONOO‑), which is decomposed into nitrite and nitrate, did not. The results of the present study suggest the gas plasma treatment inactivates bacterial spores primarily by generating hydrogen peroxide, which contributes to the oxidation of the host genomic DNA.

The Influences of Water Vapor/Hydrogen Ratio, Gas-Flow Rate and Antimony on the Surface Oxidation of Trip Steels

International Nuclear Information System (INIS)

Kwon, You Jong; Zhu, Jing Xi; Sridhar, Seetharaman; Sohn, Il Ryong

2011-01-01

In the current paper, we are reporting the results from an investigation of the surface and sub-surface oxidation of a TRIP steel containing 2 wt.% Mn and 0.5 wt.% Al with and without 0.03 wt.% Sb. The oxidizing conditions in the gas were successively varied in terms of the linear gas flow-rate and dew-point, from conditions were gas-phase mass transport limited conditions prevailed, to those were solid state processes became the rate determining conditions. It was found, that at sufficient low oxidizing conditions (defined as flow-rate/dew-point), the metal surfaces were clear of any external oxides, and as the oxidizing conditions were increased, Mn- and Si- oxide nodules formed along with magnetite. As the oxidizing conditions were increased further, a dense magnetite layer was present. The limits of the various regions were experimentally quantified and a proposed hypothesis for their occurrences is presented. No obvious effect of Sb was noted in this micro-structural research of the oxides that results from the various conditions investigated in this study

Heterogeneous metal-oxide nanowire micro-sensor array for gas sensing

International Nuclear Information System (INIS)

DeMeo, Dante; E Vandervelde, Thomas; MacNaughton, Sam; Sonkusale, Sameer; Wang, Zhilong; Zhang, Xinjie

2014-01-01

Vanadium oxide, manganese oxide, tungsten oxide, and nickel oxide nanowires were investigated for their applicability as chemiresistive gas sensors. Nanowires have excellent surface-to-volume ratios which yield higher sensitivities than bulk materials. Sensing elements consisting of these materials were assembled in an array to create an electronic nose platform. Dielectrophoresis was used to position the nanomaterials onto a microfabricated array of electrodes, which was subsequently mounted onto a leadless chip carrier and printed circuit board for rapid testing. Samples were tested in an enclosed chamber with vapors of acetone, isopropanol, methanol, and aqueous ammonia. The change in resistance of each assembly was measured. Responses varied between nanowire compositions, each demonstrating unique and repeatable responses to different gases; this enabled direct detection of the gases from the ensemble response. Sensitivities were calculated based on the fractional resistance change in a saturated environment and ranged from 6 × 10 −4 to 2 × 10 −5 %change ppm −1 . (papers)

Synthesis and evaluation of gas sensing properties of PANI based graphene oxide nanocomposites

International Nuclear Information System (INIS)

Gaikwad, Ganesh; Patil, Pritam; Patil, Devidas; Naik, Jitendra

2017-01-01

Highlights: • Developed GO, ZnO, PANI nanocomposites. • Evaluated for effect of GO addition on gas sensing performance. • Performed ammonia gas sensing at room temperature. • Obtained excellent recovery time of gas sensor. - Abstract: Polyaniline (PANI) nanofibers and Polyaniline/Graphene Oxide (PANI/GO), Polyaniline/Graphene Oxide/Zinc Oxide (PANI/GO/ZnO) nanocomposites were successfully prepared by nanoemulsion method. The synthesized nanofibers and nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Field emission scanning electron microscope (FE-SEM), has showed the evidence of interaction between PANI nanofibers, GO nanosheets and ZnO nanoparticles, respectively. PANI nanofibers and nanocomposites were used for the sensing of NH_3_, LPG, CO_2 and H_2S gases respectively at room temperature. It was observed that the PANI nanofibers and PANI/GO, PANI/GO/ZnO nanocomposites with different weight ratios of ZnO and GO had better selectivity and sensitivity towards NH_3 at room temperature. Best performance was shown by PANI/GO/ZnO nanocomposite response of 5.706 (10.3 times better response than PANI sensor) for 1000 ppm NH_3 at 80 ± 1 °C with the recovery time of 1 min 30 s only.

Synthesis and evaluation of gas sensing properties of PANI based graphene oxide nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Gaikwad, Ganesh [Department of Chemical Engineering, University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, Maharashtra (India); Patil, Pritam [SVMIT, College of Engineering, Bharuch 392001, Gujarat (India); Patil, Devidas [Bulk and Nanomaterials Research Laboratory, Rani Laxmibai Mahavidyalaya Parola, Jalgaon 425111, Maharashtra (India); Naik, Jitendra, E-mail: jbnaik@nmu.ac.in [Department of Chemical Engineering, University Institute of Chemical Technology, North Maharashtra University, Jalgaon 425001, Maharashtra (India)

2017-04-15

Highlights: • Developed GO, ZnO, PANI nanocomposites. • Evaluated for effect of GO addition on gas sensing performance. • Performed ammonia gas sensing at room temperature. • Obtained excellent recovery time of gas sensor. - Abstract: Polyaniline (PANI) nanofibers and Polyaniline/Graphene Oxide (PANI/GO), Polyaniline/Graphene Oxide/Zinc Oxide (PANI/GO/ZnO) nanocomposites were successfully prepared by nanoemulsion method. The synthesized nanofibers and nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Field emission scanning electron microscope (FE-SEM), has showed the evidence of interaction between PANI nanofibers, GO nanosheets and ZnO nanoparticles, respectively. PANI nanofibers and nanocomposites were used for the sensing of NH{sub 3,} LPG, CO{sub 2} and H{sub 2}S gases respectively at room temperature. It was observed that the PANI nanofibers and PANI/GO, PANI/GO/ZnO nanocomposites with different weight ratios of ZnO and GO had better selectivity and sensitivity towards NH{sub 3} at room temperature. Best performance was shown by PANI/GO/ZnO nanocomposite response of 5.706 (10.3 times better response than PANI sensor) for 1000 ppm NH{sub 3} at 80 ± 1 °C with the recovery time of 1 min 30 s only.

Online gas composition estimation in solid oxide fuel cell systems with anode off-gas recycle configuration

Science.gov (United States)

Dolenc, B.; Vrečko, D.; Juričić, Ð.; Pohjoranta, A.; Pianese, C.

2017-03-01

Degradation and poisoning of solid oxide fuel cell (SOFC) stacks are continuously shortening the lifespan of SOFC systems. Poisoning mechanisms, such as carbon deposition, form a coating layer, hence rapidly decreasing the efficiency of the fuel cells. Gas composition of inlet gases is known to have great impact on the rate of coke formation. Therefore, monitoring of these variables can be of great benefit for overall management of SOFCs. Although measuring the gas composition of the gas stream is feasible, it is too costly for commercial applications. This paper proposes three distinct approaches for the design of gas composition estimators of an SOFC system in anode off-gas recycle configuration which are (i.) accurate, and (ii.) easy to implement on a programmable logic controller. Firstly, a classical approach is briefly revisited and problems related to implementation complexity are discussed. Secondly, the model is simplified and adapted for easy implementation. Further, an alternative data-driven approach for gas composition estimation is developed. Finally, a hybrid estimator employing experimental data and 1st-principles is proposed. Despite the structural simplicity of the estimators, the experimental validation shows a high precision for all of the approaches. Experimental validation is performed on a 10 kW SOFC system.

Clad modified optical fiber gas sensors based on nanocrystalline nickel oxide embedded coatings

Science.gov (United States)

Yamini, K.; Renganathan, B.; Ganesan, A. R.; Prakash, T.

2017-07-01

A clad modified optical fiber gas sensor for sensing volatile organic compound vapours (VOCs) such as formaldehyde (HCHO), ammonia (NH3), ethanol (C2H5OH) and methanol (CH3OH) up to 500 ppm was studied using nanocrystalline nickel oxide embedded coatings. Prior to the measurements, nickel oxide in two different crystallite sizes such as 24 nm and 76 nm was synthesized by calcination of reverse precipitated nickel hydroxide subsequently at 450 °C and 900 °C for 30 min. Then, samples physical properties were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Our gas sensing measurement concludes that the lower crystallite size (24 nm) nickel oxide nanocrystals exhibits superior performance to formaldehyde and ethanol vapours as compared with other two VOCs, the observed experimental results were discussed in detail.

A Gas Cell Based on Hollow-Core Photonic Crystal Fiber (PCF and Its Application for the Detection of Greenhouse Gas (GHG: Nitrous Oxide (N2O

Directory of Open Access Journals (Sweden)

Jonas K. Valiunas

2016-01-01

Full Text Available The authors report the detection of nitrous oxide gas using intracavity fiber laser absorption spectroscopy. A gas cell based on a hollow-core photonic crystal fiber was constructed and used inside a fiber ring laser cavity as an intracavity gas cell. The fiber laser in the 1.55 μm band was developed using a polarization-maintaining erbium-doped fiber as the gain medium. The wavelength of the laser was selected by a fiber Bragg grating (FBG, and it matches one of the absorption lines of the gas under investigation. The laser wavelength contained multilongitudinal modes, which increases the sensitivity of the detection system. N2O gas has overtones of the fundamental absorption bands and rovibrational transitions in the 1.55 μm band. The system was operated at room temperature and was capable of detecting nitrous oxide gas at sub-ppmv concentration level.

Comprehensive Analysis of the Gas- and Particle-Phase Products of VOC Oxidation

Science.gov (United States)

Bakker-Arkema, J.; Ziemann, P. J.

2017-12-01

Controlled environmental chamber studies are important for determining atmospheric reaction mechanisms and gas and aerosol products formed in the oxidation of volatile organic compounds (VOCs). Such information is necessary for developing detailed chemical models for use in predicting the atmospheric fate of VOCs and also secondary organic aerosol (SOA) formation. However, complete characterization of atmospheric oxidation reactions, including gas- and particle-phase product yields, and reaction branching ratios, are difficult to achieve. In this work, we investigated the reactions of terminal and internal alkenes with OH radicals in the presence of NOx in an attempt to fully characterize the chemistry of these systems while minimizing and accounting for the inherent uncertainties associated with environmental chamber experiments. Gas-phase products (aldehydes formed by alkoxy radical decomposition) and particle-phase products (alkyl nitrates, β-hydroxynitrates, dihydroxynitrates, 1,4-hydroxynitrates, 1,4-hydroxycarbonyls, and dihydroxycarbonyls) formed through pathways involving addition of OH to the C=C double bond as well as H-atom abstraction were identified and quantified using a suite of analytical techniques. Particle-phase products were analyzed in real time with a thermal desorption particle beam mass spectrometer; and off-line by collection onto filters, extraction, and subsequent analysis of functional groups by derivatization-spectrophotometric methods developed in our lab. Derivatized products were also separated by liquid chromatography for molecular quantitation by UV absorbance and identification using chemical ionization-ion trap mass spectrometry. Gas phase aldehydes were analyzed off-line by collection onto Tenax and a 5-channel denuder with subsequent analysis by gas chromatography, or by collection onto DNPH-coated cartridges and subsequent analysis by liquid chromatography. The full product identification and quantitation, with careful

Multilayered metal oxide thin film gas sensors obtained by conventional and RF plasma-assisted laser ablation

International Nuclear Information System (INIS)

Mitu, B.; Marotta, V.; Orlando, S.

2006-01-01

Multilayered thin films of In 2 O 3 and SnO 2 have been deposited by conventional and RF plasma-assisted reactive pulsed laser ablation, with the aim to evaluate their behaviour as toxic gas sensors. The depositions have been carried out by a frequency doubled Nd-YAG laser (λ = 532 nm, τ = 7 ns) on Si(1 0 0) substrates, in O 2 atmosphere. The thin films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrical resistance measurements. A comparison of the electrical response of the simple (indium oxide, tin oxide) and multilayered oxides to toxic gas (nitric oxide, NO) has been performed. The influence on the structural and electrical properties of the deposition parameters, such as substrate temperature and RF power is reported

75 FR 30392 - Transparency Provisions of Section 23 of the Natural Gas Act; Notice of Extension of Time

Science.gov (United States)

2010-06-01

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. RM07-10-002] Transparency Provisions of Section 23 of the Natural Gas Act; Notice of Extension of Time May 24, 2010. In comments following the March 25, 2010 Technical Conference in the above-referenced proceeding, the Natural Gas Supply...

A study of the accelerated zircaloy-4 oxidation reaction with H2O/H2 mixture gas

International Nuclear Information System (INIS)

Kim, Y. S.; Cho, I. J.

2001-01-01

A study of the Zircaloy-4 reaction with H 2 O/H 2 mixture gas is carried out by using TGA (Thermo Gravimetric Apparatus) to estimate the hydrogen embrittlement which can possibly cause catastrophic nuclear fuel rod failure. Reaction rates are measured as a function of H 2 /H 2 O. In the experiments reaction temperature is set at 500 .deg. C and total pressure of the mixture gas is maintained at 1 atm. Experimental results reveal that hydriding and oxidation reaction are competing. In early stage, hydriding kinetics is faster than oxidation, however, oxidant in H 2 O forms oxide on the surface as steam environment is maintained, thus, this growing oxide begins to protect the zirconium base metal against hydrogen permeation. In this second stage, the total kinetic rate follows enhanced oxidation kinetics. In the final stage, it is observed that the oxide is broken down and massive hydriding takes place through the mechanical defects in the oxide, whose kinetics is similar to pure hydriding kinetics. These results are confirmed by SEM and EDX analysis along with hydrogen concentration measurements

Gas-Phase Oxidation of Aqueous Ethanol by Nanoparticle Vanadia/Anatase Catalysts

DEFF Research Database (Denmark)

Jørgensen, Betina; Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas

2009-01-01

The gas-phase oxidation of aqueous ethanol with dioxygen has been examined with a new nanoparticle V2O5/TiO2 catalyst. Product selectivity could to a large extent be controlled by small alterations of reaction parameters, allowing production of acetaldehyde at a selectivity higher than 90%, near...

Gas chromatography of adducts of rare earth dipivaloylmethanates with triphenylphosphine oxide

International Nuclear Information System (INIS)

Magazeeva, N.V.; Martynenko, L.I.; Murav'eva, I.A.; Spitsyn, V.I.

1987-01-01

A gas chromatographic method for determination of stability provisional constants of dipivaloylmethanates of REE with triphenylphosphine oxide is suggested, and ML 3 xTPPO adduct stability is shown to decrease in Ho-Lu series. ML 3 chromatographing at the presence of TPPO is stated to increase the coefficients of REE separation

Application of the Coasting Trade Act to offshore oil and gas operations

International Nuclear Information System (INIS)

De Jonge, B.B.

2002-01-01

The main features of the 1992 Coasting Trade Act are summarized. The main purpose of the Act is to protect Canadian ship owners and to ensure they have an opportunity to recover their investments in having Canadian built and crewed vessels. The Coasting Trade Act replaces provisions of the Canada Shipping Act which prohibited non-British ships from entering into Canadian domestic trade. The intention for the Coasting Trade Act is to reserve the coasting trade of Canada to Canadian-registered ships. However, when a Canadian ship is not available, a suitable foreign ship may be temporarily permitted to engage in the Canadian coasting trade as long as Canadian safety standards are met and duties are paid. The Canada Customs and Revenue Agency deals with licence applications while the Canadian Transportation Agency deals with unfair practices and enforcement. The provisions relating to the Coasting Trade License applications are examined along with how they are administered with particular reference to offshore oil and gas operations. The paper also presents recent decisions regarding application licences for Tycom (US) Inc., the Norwegian Polar Ship Management, and the Cyprus-registered seismic vessel, the Northern Access. It is noted that in evaluating the suitability and availability of a Canadian vessel for an activity proposed to be performed by a foreign vessel, the Canadian Transportation Agency examines the technical, financial and commercial elements brought by the parties

Gas-permeation properties of poly(ethylene oxide) poly(butylene terephthalate block copolymers

NARCIS (Netherlands)

Metz, S.J.; Mulder, M.H.V.; Wessling, Matthias

2004-01-01

This paper reports the gas-permeation properties of poly(ethylene oxide) (PEO) poly(butylene terephthalate) (PBT) segmented multiblock copolymers. These block copolymers allow a precise structural modification by the amount of PBT and the PEO segment length, enabling a systematic study of the

Nanoscale Metal Oxide Semiconductors for Gas Sensing

Science.gov (United States)

Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

2011-01-01

A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical

The Measurement of Fuel-Air Ratio by Analysis for the Oxidized Exhaust Gas

Science.gov (United States)

Gerrish, Harold C.; Meem, J. Lawrence, Jr.

1943-01-01

An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy fuel Specification No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs for the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124.

The Measurement of Fuel-air Ratio by Analysis of the Oxidized Exhaust Gas

Science.gov (United States)

Memm, J. Lawrence, Jr.

1943-01-01

An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy Fuel Specification, No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs or the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124

The Role of Post Flame Oxidation on the UHC Emission for Combustion of Natural Gas and Hydrogen Containing fuels

DEFF Research Database (Denmark)

Jensen, Torben Kvist; Schramm, Jesper

2003-01-01

In-cylinder post flame oxidation of unburned hydro-carbons from crevices in a lean burn spark ignition engine has been examined for natural gas and mixtures of natural gas and a hydrogen containing producer gas. For this purpose a model was developed to describe the mixing of cold unburned...... reactants from crevices and hot burned bulk gas and to describe the oxidation of the unburned fuel. The post oxidation was described by a single step chemical reaction mechanism instead of detailed chemical kinetics in order to reduce the calculation time. However, the exploited Arrhenius expressions used...... to describe the chemical reactions were deduced from a detailed reaction mechanism. Different detailed reaction mechanisms were compared with results from combustion reactor experiments. Experiments and simulations were compared at different pressures and excesses of air similar to the conditions present...

Oxidation method of trivalent plutonium to tetravalent plutonium

International Nuclear Information System (INIS)

Ozawa, Masaki; Washitani, Tadahiro; Kawada, Tomio; Hayashi, Shotaro.

1993-01-01

The present invention concerns a Pu reoxidation step and a Pu condensation step in a purex process for recovering U and Pu in spent nuclear fuels. A nitric acid solution incorporating Pu 3+ , hydroxyl amine nitrate and hydrazine is oxidized under electrolysis. Pu 3+ is substantially completely oxidized into Pu 4+ . At the same time, also hydroxyl nitrate amine and hydrazine are substantially completely decomposed into nitrogen gas and hydrogen gas finally. Although hydroxyl nitrate amine which is a reducing agent is extremely electrochemically stable in a nitric acid solution if Pu 3+ is not present, it can be decomposed efficiently by electrolysis if Pu 3+ is present, since the latter acts as a catalyst in an electrode reaction system. (T.M.)

Gas-phase advanced oxidation for effective, efficient in situ control of pollution

DEFF Research Database (Denmark)

Johnson, Matthew Stanley; Nilsson, Elna Johanna Kristina; Svensson, Erik Anders

2014-01-01

In this article, gas-phase advanced oxidation, a new method for pollution control building on the photo-oxidation and particle formation chemistry occurring in the atmosphere, is introduced and characterized. The process uses ozone and UV-C light to produce in situ radicals to oxidize pollution......, generating particles that are removed by a filter; ozone is removed using a MnO2 honeycomb catalyst. This combination of in situ processes removes a wide range of pollutants with a comparatively low specific energy input. Two proof-of-concept devices were built to test and optimize the process...... particulate mass. Secondary pollution including formaldehyde and ultrafine particles might be generated, depending on the composition of the primary pollution....

Thermodynamic analysis of a gas turbine cycle equipped with a non-ideal adiabatic model for a double acting Stirling engine

International Nuclear Information System (INIS)

Korlu, Mahmood; Pirkandi, Jamasb; Maroufi, Arman

2017-01-01

Highlights: • A gas turbine cycle equipped with a double acting Stirling engine is proposed. • The hybrid cycle effects, efficiency and power outputs are investigated. • The energy dissipation, the net enthalpy loss and wall heat leakage are considered. • The hybrid cycle improves the efficiency from 23.6 to 38.8%. - Abstract: The aim of this study is to investigate the thermodynamic performance of a gas turbine cycle equipped with a double acting Stirling engine. A portion of gas turbine exhaust gases are allocated to providing the heat required for the Stirling engine. Employing this hybrid cycle improves gas turbine performance and power generation. The double acting Stirling engine is used in this study and the non-ideal adiabatic model is used to numerical solution. The regenerator’s net enthalpy loss, the regenerator’s wall heat leakage, the energy dissipation caused by pressure drops in heat exchangers and regenerator are the losses that were taken into account for the Stirling engine. The hybrid cycle, gas turbine governing equations and Stirling engine analyses are carried out using the Matlab software. The pressure ratio of the compressor, the inlet temperature of turbine, the porosity, length and diameter of the regenerator were chosen as essential parameters in this article. Also the hybrid cycle effects, efficiency and power outputs are investigated. The results show that the hybrid gas turbine and Stirling engine improves the efficiency from 23.6 to 38.8%.

Direct gas-phase epoxidation of propylene to propylene oxide through radical reactions: A theoretical study

Science.gov (United States)

Kizilkaya, Ali Can; Fellah, Mehmet Ferdi; Onal, Isik

2010-03-01

The gas-phase radical chain reactions which utilize O 2 as the oxidant to produce propylene oxide (PO) are investigated through theoretical calculations. The transition states and energy profiles were obtained for each path. The rate constants were also calculated. The energetics for the competing pathways indicate that PO can be formed selectively due to its relatively low activation barrier (9.3 kcal/mol) which is in a good agreement with the experimental value (11 kcal/mol) of gas-phase propylene epoxidation. The formation of the acrolein and combustion products have relatively high activation barriers and are not favored. These results also support the recent experimental findings.

Rio Vista gas leak study: Belleaire Gas Field, California

International Nuclear Information System (INIS)

Wilkey, P.L.

1992-08-01

The Rio Vista gas leak study evaluated methods for remotely sensing gas leaks from buried pipelines and developed methods to elucidate methane transport and microbial oxidation in soils. Remote-sensing methods were evaluated by singing gas leaks along an abandoned Pacific Gas and Electric (PG ampersand E) gas field collection line in northern California and applying surface-based and airborne remote-sensing techniques in the field, including thermal imaging, laser imaging, and multispectral imagery. The remote-sensing techniques exhibited limitations in range and in their ability to correlate with ground truth data. To elucidate methane transport and microbial oxidation in soils, a study of a controlled leak permitted field testing of methods so that such processes could be monitored and evaluated. Monitoring and evaluation techniques included (1) field measurement of soil-gas concentrations, temperatures, and pressures; (2) laboratory measurement of soil physical/chemical properties and activity of methane-oxidizing microorganisms by means of field samples; and (3) development of a preliminary numerical analysis technique for combined soil-gas transport/methane oxidation. Soil-gas concentrations at various depths responded rapidly to the high rate of gas leakage. The number of methane-oxidizing microorganisms in site soils rapidly increased when the gas leak was initiated and decreased after the leak was terminated. The preliminary field, laboratory, and numerical analysis techniques tested for this study of a controlled gas leak could be successfully applied to future studies of gas leaks. Because soil-gas movement is rapid and temporally variable, the use of several complementary techniques that permit generalization of site-specific results is favored

Code of Conduct for Gas Marketers : rule made under part 3 of the Ontario Energy Board Act, 1998

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-02

Text of the code of conduct for gas marketers in Ontario is presented. This code sets the minimum standards under which a gas marketer may sell or offer to sell gas to a low-volume consumer, or act as an agent or broker with respect to the sale of gas. The document describes the standards and principles regarding: (1) fair marketing practices, (2) identification, (3) information to be maintained by a gas marketer, (4) confidentiality of consumer information, (5) conditions in offers, (6) contracts, (7) contract renewals, (8) assignment, sale and transfer contracts, (9) independent arms-length consumer complaints resolution process, and (10) penalties for breach of this code.

Code of Conduct for Gas Marketers : rule made under part 3 of the Ontario Energy Board Act, 1998

International Nuclear Information System (INIS)

1999-01-01

Text of the code of conduct for gas marketers in Ontario is presented. This code sets the minimum standards under which a gas marketer may sell or offer to sell gas to a low-volume consumer, or act as an agent or broker with respect to the sale of gas. The document describes the standards and principles regarding: (1) fair marketing practices, (2) identification, (3) information to be maintained by a gas marketer, (4) confidentiality of consumer information, (5) conditions in offers, (6) contracts, (7) contract renewals, (8) assignment, sale and transfer contracts, (9) independent arms-length consumer complaints resolution process, and (10) penalties for breach of this code

Crystalline mesoporous tungsten oxide nanoplate monoliths synthesized by directed soft template method for highly sensitive NO2 gas sensor applications

International Nuclear Information System (INIS)

Hoa, Nguyen Duc; Duy, Nguyen Van; Hieu, Nguyen Van

2013-01-01

Graphical abstract: Display Omitted Highlights: ► Mesoporous WO 3 nanoplate monoliths were obtained by direct templating synthesis. ► Enable effective accession of the analytic molecules for the sensor applications. ► The WO 3 sensor exhibited a high performance to NO 2 gas at low temperature. -- Abstract: Controllable synthesis of nanostructured metal oxide semiconductors with nanocrystalline size, porous structure, and large specific surface area is one of the key issues for effective gas sensor applications. In this study, crystalline mesoporous tungsten oxide nanoplate-like monoliths with high specific surface areas were obtained through instant direct-templating synthesis for highly sensitive nitrogen dioxide (NO 2 ) sensor applications. The copolymer soft template was converted into a solid carbon framework by heat treatment in an inert gas prior to calcinations in air to sustain the mesoporous structure of tungsten oxide. The multidirectional mesoporous structures of tungsten oxide with small crystalline size, large specific surface area, and superior physical characteristics enabled the rapid and effective accession of analytic gas molecules. As a result, the sensor response was enhanced and the response and recovery times were reduced, in which the mesoporous tungsten oxide based gas sensor exhibited a superior response of 21,155% to 5 ppm NO 2 . In addition, the developed sensor exhibited selective detection of low NO 2 concentration in ammonia and ethanol at a low temperature of approximately 150 °C.

Use of gas-phase ethanol to mitigate extreme UV/water oxidation of extreme UV optics

Science.gov (United States)

Klebanoff, L. E.; Malinowski, M. E.; Clift, W. M.; Steinhaus, C.; Grunow, P.

2004-03-01

A technique is described that uses a gas-phase species to mitigate the oxidation of a Mo/Si multilayer optic caused by either extreme UV (EUV) or electron-induced dissociation of adsorbed water vapor. It is found that introduction of ethanol (EtOH) into a water-rich gas-phase environment inhibits oxidation of the outermost Si layer of the Mo/Si EUV reflective coating. Auger electron spectroscopy, sputter Auger depth profiling, EUV reflectivity, and photocurrent measurements are presented that reveal the EUV/water- and electron/water-derived optic oxidation can be suppressed at the water partial pressures used in the tests (~2×10-7-2×10-5 Torr). The ethanol appears to function differently in two time regimes. At early times, ethanol decomposes on the optic surface, providing reactive carbon atoms that scavenge reactive oxygen atoms before they can oxidize the outermost Si layer. At later times, the reactive carbon atoms form a thin (~5 Å), possibly self-limited, graphitic layer that inhibits water adsorption on the optic surface. .

Integrating Metal-Oxide-Decorated CNT Networks with a CMOS Readout in a Gas Sensor

Directory of Open Access Journals (Sweden)

Suhwan Kim

2012-02-01

Full Text Available We have implemented a tin-oxide-decorated carbon nanotube (CNT network gas sensor system on a single die. We have also demonstrated the deposition of metallic tin on the CNT network, its subsequent oxidation in air, and the improvement of the lifetime of the sensors. The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy. The read-out integrated circuit (ROIC was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way. The ROIC is fabricated using a 0.35 µm CMOS process, and the whole sensor system consumes 30 mA at 5 V. The sensor system was successfully tested in the detection of ammonia gas at elevated temperatures.

Improving methane gas sensing properties of multi-walled carbonnanotubes by vanadium oxide filling

CSIR Research Space (South Africa)

Chimowa, George

2017-08-01

Full Text Available Manipulation of electrical properties and hence gas sensing properties of multi-walled carbon nanotubes (MWNTs) by filling the inner wall with vanadium oxide is presented. Using a simple capillary technique, MWNTs are filled with vanadium metal...

Staged membrane oxidation reactor system

Science.gov (United States)

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2012-09-11

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

The GC/AED studies on the reactions of sulfur mustard with oxidants

International Nuclear Information System (INIS)

Popiel, StanisIaw; Witkiewicz, Zygfryd; Szewczuk, Aleksander

2005-01-01

A gas chromatograph coupled with an atomic emission detector was used to identify and to determine the products formed on oxidation of sulfur mustard. The oxidation rate and the resulting oxidates were studied in relation to oxidant type and reaction medium parameters. Hydrogen peroxide, sodium hypochlorite, sodium perborate, potassium monopercarbonate, ammonium peroxydisulfate, potassium peroxymonosulfate (oxone), and tert-butyl peroxide were used as oxidants. Oxidations were run in aqueous media or in solvents of varying polarities. The oxidation rate was found to be strongly related to oxidant type: potassium peroxymonosulfate (oxone) and sodium hypochlorite were fast-acting oxidants; sodium perborate, hydrogen peroxide, ammonium peroxydisulfate, and sodium monopercarbonate were moderate oxidants; tert-butyl peroxide was the slowest-acting oxidant. In non-aqueous solvents, the oxidation rate was strongly related to solvent polarity. The higher the solvent polarity, the faster the oxidation rate. In the acid and neutral media, the mustard oxidation rates were comparable. In the alkaline medium, oxidation was evidently slower. A suitable choice of the initial oxidant-to-mustard concentration ratio allowed to control the type of the resulting mustard oxidates. As the pH of the reaction medium was increased, the reaction of elimination of hydrogen chloride from mustard oxidates becomes more and more intensive

Partial catalytic oxidation of CH{sub 4} to synthesis gas for power generation - Final report

Energy Technology Data Exchange (ETDEWEB)

Mantzaras, I.; Schneider, A.

2006-03-15

The partial oxidation of methane to synthesis gas over rhodium catalysts has been investigated experimentally and numerically in the pressure range of 4 to 10 bar. The methane/oxidizer feed has been diluted with large amounts of H{sub 2}O and CO{sub 2} (up to 70% vol.) in order to simulate new power generation cycles with large exhaust gas recycle. Experiments were carried out in an optically accessible channel-flow reactor that facilitated laser-based in situ measurements, and also in a subscale gas-turbine catalytic reactor. Full-elliptic steady and transient two-dimensional numerical codes were used, which included elementary hetero-/homogeneous chemical reaction schemes. The following are the key conclusions: a) Heterogeneous (catalytic) and homogeneous (gas-phase) schemes have been validated for the partial catalytic oxidation of methane with large exhaust gas recycle. b) The impact of added H{sub 2}O and CO{sub 2} has been elucidated. The added H{sub 2}O increased the methane conversion and hydrogen selectivity, while it decreased the CO selectivity. The chemical impact of CO{sub 2} (dry reforming) was minimal. c) The numerical model reproduced the measured catalytic ignition times. It was further shown that the chemical impact of H{sub 2}O and CO{sub 2} on the catalytic ignition delay times was minimal. d) The noble metal dispersion increased with different support materials, in the order Rh/{alpha}-Al{sub 2}O{sub 3}, Rh/ZrO{sub 2}, and Rh/Ce-ZrO{sub 2}. An evident relationship was established between the noble metal dispersion and the catalytic behavior. (authors)

Sulfur oxides and nitrogen oxides gas treating process

International Nuclear Information System (INIS)

Forbes, J. T.

1985-01-01

A process is disclosed for treating particle-containing gas streams by removing particles and gaseous atmospheric pollutants. Parallel passage contactors are utilized to remove the gaseous pollutants. The minimum required gas flow rate for effective operation of these contactors is maintained by recycling a variable amount of low temperature gas which has been passed through a particle removal zone. The recycled gas is reheated by heat exchange against a portion of the treated gas

Dissolving method for nuclear fuel oxide

International Nuclear Information System (INIS)

Tomiyasu, Hiroshi; Kataoka, Makoto; Asano, Yuichiro; Hasegawa, Shin-ichi; Takashima, Yoichi; Ikeda, Yasuhisa.

1996-01-01

In a method of dissolving oxides of nuclear fuels in an aqueous acid solution, the oxides of the nuclear fuels are dissolved in a state where an oxidizing agent other than the acid is present together in the aqueous acid solution. If chlorate ions (ClO 3 - ) are present together in the aqueous acid solution, the chlorate ions act as a strong oxidizing agent and dissolve nuclear fuels such as UO 2 by oxidation. In addition, a Ce compound which generates Ce(IV) by oxidation is added to the aqueous acid solution, and an ozone (O 3 ) gas is blown thereto to dissolve the oxides of nuclear fuels. Further, the oxides of nuclear fuels are oxidized in a state where ClO 2 is present together in the aqueous acid solution to dissolve the oxides of nuclear fuels. Since oxides of the nuclear fuels are dissolved in a state where the oxidizing agent is present together as described above, the oxides of nuclear fuels can be dissolved even at a room temperature, thereby enabling to use a material such as polytetrafluoroethylene and to dissolve the oxides of nuclear fuels at a reduced cost for dissolution. (T.M.)

Nitrous oxide (laughing gas) inhalation as an alternative to electroconvulsive therapy.

Science.gov (United States)

Milne, Brian

2010-05-01

Electroconvulsive therapy (ECT) is used widely in the treatment of psychiatric conditions; however, its use is not without controversy with some recommending a moratorium on its clinical use. Complications and side effects of ECT include memory loss, injury, problems originating from sympathetic stimulation such as arrhythmias and myocardial ischemia and the risk of general anesthesia. Nitrous oxide (laughing gas) could potentially substitute for ECT as it shares some similar effects, has potential beneficial properties for these psychiatric patients and is relatively safe and easy to administer. Nitrous oxide induces laughter which has been described as nature's epileptoid catharsis which one might surmise would be beneficial for depression. It also produces a central sympathetic stimulation similar to ECT and causes release of endogenous opioid peptides, which are potential candidates for the development of antidepressant drugs. Nitrous oxide is also associated with seizure like activity itself. Administration of nitrous oxide as a substitute for ECT is eminently feasible and could be given in a series of treatments similar to ECT therapy.

Comparison of Elemental Mercury Oxidation Across Vanadium and Cerium Based Catalysts in Coal Combustion Flue Gas: Catalytic Performances and Particulate Matter Effects.

Science.gov (United States)

Wan, Qi; Yao, Qiang; Duan, Lei; Li, Xinghua; Zhang, Lei; Hao, Jiming

2018-03-06

This paper discussed the field test results of mercury oxidation activities over vanadium and cerium based catalysts in both coal-fired circulating fluidized bed boiler (CFBB) and chain grate boiler (CGB) flue gases. The characterizations of the catalysts and effects of flue gas components, specifically the particulate matter (PM) species, were also discussed. The catalytic performance results indicated that both catalysts exhibited mercury oxidation preference in CGB flue gas rather than in CFBB flue gas. Flue gas component studies before and after dust removal equipment implied that the mercury oxidation was well related to PM, together with gaseous components such as NO, SO 2 , and NH 3 . Further investigations demonstrated a negative PM concentration-induced effect on the mercury oxidation activity in the flue gases before the dust removal, which was attributed to the surface coverage by the large amount of PM. In addition, the PM concentrations in the flue gases after the dust removal failed in determining the mercury oxidation efficiency, wherein the presence of different chemical species in PM, such as elemental carbon (EC), organic carbon (OC) and alkali (earth) metals (Na, Mg, K, and Ca) in the flue gases dominated the catalytic oxidation of mercury.

Measurement system for nitrous oxide based on amperometric gas sensor

Science.gov (United States)

Siswoyo, S.; Persaud, K. C.; Phillips, V. R.; Sneath, R.

2017-03-01

It has been well known that nitrous oxide is an important greenhouse gas, so monitoring and control of its concentration and emission is very important. In this work a nitrous oxide measurement system has been developed consisting of an amperometric sensor and an appropriate lab-made potentiostat that capable measuring picoampere current ranges. The sensor was constructed using a gold microelectrode as working electrode surrounded by a silver wire as quasi reference electrode, with tetraethyl ammonium perchlorate and dimethylsulphoxide as supporting electrolyte and solvent respectively. The lab-made potentiostat was built incorporating a transimpedance amplifier capable of picoampere measurements. This also incorporated a microcontroller based data acquisition system, controlled by a host personal computer using a dedicated computer program. The system was capable of detecting N2O concentrations down to 0.07 % v/v.

Pressurization of Containment Vessels from Plutonium Oxide Contents

International Nuclear Information System (INIS)

Hensel, S.

2012-01-01

Transportation and storage of plutonium oxide is typically done using a convenience container to hold the oxide powder which is then placed inside a containment vessel. Intermediate containers which act as uncredited confinement barriers may also be used. The containment vessel is subject to an internal pressure due to several sources including; (1) plutonium oxide provides a heat source which raises the temperature of the gas space, (2) helium generation due to alpha decay of the plutonium, (3) hydrogen generation due to radiolysis of the water which has been adsorbed onto the plutonium oxide, and (4) degradation of plastic bags which may be used to bag out the convenience can from a glove box. The contributions of these sources are evaluated in a reasonably conservative manner.

Performance evaluation of a fuel cell with NiO-YSV anode operating with natural gas; Avaliacao do desempenho de uma celula a combustivel com anodo de NiO YSZ operando com gas natural

Energy Technology Data Exchange (ETDEWEB)

Nobrega, Shayenne Diniz da; Vasconcelos, Carmel Suzarte Ayres; Lima, Luiz Rogerio Pinho de Andrade [Universidade Federal da Bahia (UFBa), Salvador, BA (Brazil). Escola Politecnica. Dept. de Ciencia e Tecnologia dos Materiais]. E-mail: shayennedn@yahoo.com.br

2008-07-01

Fuel cell is an electrochemical device that converts the chemical energy into electric energy. The natural gas, for its proven improvement in the income of the equipment in relation to other energy ones, has been very used to feed the solid oxide fuel cell (SOFC) in the generation of electric power. Ceramics of Yttria-stabilized zirconia had been used as electrolyte and when supported with nickel oxide they act as anode in the solid oxide fuel cell, due to raised ionic conductivity that these materials present in high temperatures, while lanthanum with strontium and manganite are used as cathode. In the composition of the anode, the concentration of Ni O, acting as catalytic in the YSZ confers high electric conductivity and high electrochemical activity of the reactions, providing the internal reform in the SOFC. In this work, the solid oxide fuel cell, formed by Yttria- stabilized zirconia, nickel oxide, and lanthanum with strontium and manganite were tested in the reform had been prepared samples of electrode/electrolyte for use in SOFC of the natural gas in the presence of low water text, similar condition to the operation of the SOFC, operating in temperatures range from 700 to 800 deg C. This cell also was characterized using the impedance spectroscopy technique. These results allowed the development of components of the current versus voltage. (author)

Thermodynamic Performance Study of Biomass Gasification, Solid Oxide Fuel Cell and Micro Gas Turbine Hybrid Systems

DEFF Research Database (Denmark)

Bang-Møller, Christian; Rokni, Masoud

2010-01-01

A system level modelling study of three combined heat and power systems based on biomass gasification is presented. Product gas is converted in a micro gas turbine (MGT) in the first system, in a solid oxide fuel cell (SOFC) in the second system and in a combined SOFC–MGT arrangement in the third...

Thermochemical Analysis of Gas-Cooled Reactor Fuels Containing Am and Pu Oxides

International Nuclear Information System (INIS)

Lindemer, T.B.

2002-01-01

Literature values and estimated data for the thermodynamics of the actinide oxides and fission products are applied to explain the chemical behavior in gas-cooled-reactor fuels. Emphasis is placed on the Am-O-C and Pu-O-C systems and the data are used to plot the oxygen chemical potential versus temperature of solid-solid and solid-gas equilibria. These results help explain observations of vaporization in Am oxides, nitrides, and carbides and provide guidance for the ceramic processing of the fuels. The thermodynamic analysis is then extended to the fission product systems and the Si-C-O system. Existing data on oxygen release (primarily as CO) as a function of burnup in the thoria-urania fuel system is reviewed and compared to values calculated from thermodynamic data. The calculations of oxygen release are then extended to the plutonia and americia fuels. Use of ZrC not only as a particle coating that may be more resistant to corrosion by Pd and other noble-metal fission products, but also as a means to getter oxygen released by fission is discussed

Tuneable diode laser gas analyser for methane measurements on a large scale solid oxide fuel cell

Science.gov (United States)

Lengden, Michael; Cunningham, Robert; Johnstone, Walter

2011-10-01

A new in-line, real time gas analyser is described that uses tuneable diode laser spectroscopy (TDLS) for the measurement of methane in solid oxide fuel cells. The sensor has been tested on an operating solid oxide fuel cell (SOFC) in order to prove the fast response and accuracy of the technology as compared to a gas chromatograph. The advantages of using a TDLS system for process control in a large-scale, distributed power SOFC unit are described. In future work, the addition of new laser sources and wavelength modulation will allow the simultaneous measurement of methane, water vapour, carbon-dioxide and carbon-monoxide concentrations.

Nitric oxide coordinates metabolism, growth, and development via the nuclear receptor E75.

Science.gov (United States)

Cáceres, Lucía; Necakov, Aleksandar S; Schwartz, Carol; Kimber, Sandra; Roberts, Ian J H; Krause, Henry M

2011-07-15

Nitric oxide gas acts as a short-range signaling molecule in a vast array of important physiological processes, many of which include major changes in gene expression. How these genomic responses are induced, however, is poorly understood. Here, using genetic and chemical manipulations, we show that nitric oxide is produced in the Drosophila prothoracic gland, where it acts via the nuclear receptor ecdysone-induced protein 75 (E75), reversing its ability to interfere with its heterodimer partner, Drosophila hormone receptor 3 (DHR3). Manipulation of these interactions leads to gross alterations in feeding behavior, fat deposition, and developmental timing. These neuroendocrine interactions and consequences appear to be conserved in vertebrates.

Boltorn-Modified Poly(2,6-dimethyl-1,4,phenylene oxide) Gas Separation Membranes

NARCIS (Netherlands)

Sterescu, D.M.; Stamatialis, Dimitrios; Mendes, Eduardo; Kruse, Jan; Rätzke, Klaus; Faupel, Franz; Wessling, Matthias

2007-01-01

This paper describes the preparation, characterization and the permeation properties of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) dense polymer films containing aliphatic hyperbranched polyesters, Boltorn (H20, H30, and H40). The Boltorn are dispersed in PPO at various concentrations. The gas

Mechanism and Microstructure of Oxide Fluxes for Gas Tungsten Arc Welding of Magnesium Alloy

Science.gov (United States)

Liu, L. M.; Zhang, Z. D.; Song, G.; Wang, L.

2007-03-01

Five single oxide fluxes—MgO, CaO, TiO2, MnO2, and Cr2O3—were used to investigate the effect of active flux on the depth/width ratio in AZ31B magnesium alloy. The microstructure and mechanical property of the tungsten inert gas (TIG) welding seam were studied. The oxygen content in the weld seam and the arc images during the TIG welding process were analyzed. A series of emission spectroscopy of weld arc for TIG welding for magnesium with and without flux were developed. The results showed that for the five single oxide fluxes, all can increase the weld penetration effectively and grain size in the weld seam of alternating current tungsten inert gas (ACTIG) welding of the Mg alloy. The oxygen content of the welds made without flux is not very different from those produced with oxide fluxes not considering trapped oxide. However, welds that have the best penetration have a relatively higher oxygen content among those produced with flux. It was found that the arc images with the oxide fluxes were only the enlarged form of the arc images without flux; the arc constriction was not observed. The detection of arc spectroscopy showed that the metal elements in the oxides exist as the neutral atom or the first cation in the weld arc. This finding would influence the arc properties. When TIG simulation was carried out on a plate with flux applied only on one side, the arc image video showed an asymmetric arc, which deviated toward the flux free side. The thermal stability, the dissociation energy, and the electrical conductivity of oxide should be considered when studying the mechanism for increased TIG flux weld penetration.

Sulfur isotope fractionation during oxidation of sulfur dioxide: gas-phase oxidation by OH radicals and aqueous oxidation by H2O2, O3 and iron catalysis

Directory of Open Access Journals (Sweden)

J. N. Crowley

2012-01-01

Full Text Available The oxidation of SO2 to sulfate is a key reaction in determining the role of sulfate in the environment through its effect on aerosol size distribution and composition. Sulfur isotope analysis has been used to investigate sources and chemical processes of sulfur dioxide and sulfate in the atmosphere, however interpretation of measured sulfur isotope ratios is challenging due to a lack of reliable information on the isotopic fractionation involved in major transformation pathways. This paper presents laboratory measurements of the fractionation factors for the major atmospheric oxidation reactions for SO2: Gas-phase oxidation by OH radicals, and aqueous oxidation by H2O2, O3 and a radical chain reaction initiated by iron. The measured fractionation factor for 34S/32S during the gas-phase reaction is αOH = (1.0089±0.0007−((4±5×10−5 T(°C. The measured fractionation factor for 34S/32S during aqueous oxidation by H2O2 or O3 is αaq = (1.0167±0.0019−((8.7±3.5 ×10−5T(°C. The observed fractionation during oxidation by H2O2 and O3 appeared to be controlled primarily by protonation and acid-base equilibria of S(IV in solution, which is the reason that there is no significant difference between the fractionation produced by the two oxidants within the experimental error. The isotopic fractionation factor from a radical chain reaction in solution catalysed by iron is αFe = (0.9894±0.0043 at 19 °C for 34S/32S. Fractionation was mass-dependent with regards to 33S/32S for all the reactions investigated. The radical chain reaction mechanism was the only measured reaction that had a faster rate for the light isotopes. The results presented in this study will be particularly useful to determine the importance of the transition metal-catalysed oxidation pathway compared to other oxidation pathways, but other main oxidation pathways can not be distinguished based on stable sulfur isotope measurements alone.

Porous screen printed indium tin oxide (ITO) for NOx gas sensing

International Nuclear Information System (INIS)

Mbarek, H.; Saadoun, M.; Bessais, B.

2007-01-01

Tin-doped Indium Oxide (ITO) films were prepared by the screen printing method. Transparent and conductive ITO thin films were obtained from an organometallic based paste fired in an Infrared furnace. The Screen printed ITO films were found to be granular and porous. This specific morphology was found to be suitable for sensing different gaseous species. This work investigates the possibility of using screen printed (ITO) films as a specific material for efficient NO x gas sensing. It was found that screen printed ITO is highly sensitive and stable towards NO x , especially for gas concentration higher than 50 ppm and starting from a substrate working temperature of about 180 C. The sensitivity of the ITO films increases with increasing NO x concentration and temperature. The sensitivity and stability of the screen printed ITO based sensors were studied within time. The ITO crystallite grain size dimension was found to be a key parameter that influences the gas response characteristics. Maximum gas sensitivity and minimum response time were observed for ITO films having lower crystallite size dimensions. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Crystalline mesoporous tungsten oxide nanoplate monoliths synthesized by directed soft template method for highly sensitive NO{sub 2} gas sensor applications

Energy Technology Data Exchange (ETDEWEB)

Hoa, Nguyen Duc, E-mail: ndhoa@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST) (Viet Nam); Duy, Nguyen Van [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST) (Viet Nam); Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST) (Viet Nam)

2013-02-15

Graphical abstract: Display Omitted Highlights: ► Mesoporous WO{sub 3} nanoplate monoliths were obtained by direct templating synthesis. ► Enable effective accession of the analytic molecules for the sensor applications. ► The WO{sub 3} sensor exhibited a high performance to NO{sub 2} gas at low temperature. -- Abstract: Controllable synthesis of nanostructured metal oxide semiconductors with nanocrystalline size, porous structure, and large specific surface area is one of the key issues for effective gas sensor applications. In this study, crystalline mesoporous tungsten oxide nanoplate-like monoliths with high specific surface areas were obtained through instant direct-templating synthesis for highly sensitive nitrogen dioxide (NO{sub 2}) sensor applications. The copolymer soft template was converted into a solid carbon framework by heat treatment in an inert gas prior to calcinations in air to sustain the mesoporous structure of tungsten oxide. The multidirectional mesoporous structures of tungsten oxide with small crystalline size, large specific surface area, and superior physical characteristics enabled the rapid and effective accession of analytic gas molecules. As a result, the sensor response was enhanced and the response and recovery times were reduced, in which the mesoporous tungsten oxide based gas sensor exhibited a superior response of 21,155% to 5 ppm NO{sub 2}. In addition, the developed sensor exhibited selective detection of low NO{sub 2} concentration in ammonia and ethanol at a low temperature of approximately 150 °C.

Graphene oxide foams and their excellent adsorption ability for acetone gas

International Nuclear Information System (INIS)

He, Yongqiang; Zhang, Nana; Wu, Fei; Xu, Fangqiang; Liu, Yu; Gao, Jianping

2013-01-01

Graphical abstract: - Highlights: • GO and RGO foams were prepared using a simple and green method, unidirectional freeze-drying. • The porous structure of the foams can be adjusted by changing GO concentrations. • GO and RGO foams show good adsorption efficiency for acetone gas. - Abstract: Graphene oxide (GO) and reduced graphene oxide (RGO) foams were prepared using a unidirectional freeze-drying method. These porous carbon materials were characterized by thermal gravimetric analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy and scanning electron microscopy. The adsorption behavior of the two kinds of foams for acetone was studied. The result showed that the saturated adsorption efficiency of the GO foams was over 100%, and was higher than that of RGO foams and other carbon materials

Removal of nitrogen compounds from gasification gas by selective catalytic or non-catalytic oxidation; Typpiyhdisteiden poisto kaasutuskaasusta selektiivisellae katalyyttisellae ja ei-katalyyttisellae hapetuksella

Energy Technology Data Exchange (ETDEWEB)

Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

1996-12-01

In gasification reactive nitrogenous compounds are formed from fuel nitrogen, which may form nitrogen oxides in gas combustion. In fluidized bed gasification the most important nitrogenous compound is ammonia (NH{sub 3}). If ammonia could be decomposed to N{sub 2} already before combustion, the emissions if nitrogen oxides could be reduced significantly. One way of increasing the decomposition rate of NH{sub 3} could be the addition of suitable reactants to the gas, which would react with NH{sub 3} and produce N{sub 2}. The aim of this research is to create basic information, which can be used to develop a new method for removal of nitrogen compounds from gasification gas. The reactions of nitrogen compounds and added reactants are studied in reductive atmosphere in order to find conditions, in which nitrogen compounds can be oxidized selectively to N{sub 2}. The project consists of following subtasks: (1) Selective non-catalytic oxidation (SNCO): Reactions of nitrogen compounds and oxidizers in the gas phase, (2) Selective catalytic oxidation (SCO): Reactions of nitrogen compounds and oxidizers on catalytically active surfaces, (3) Kinetic modelling of experimental results in co-operation with the Combustion Chemistry Research Group of Aabo Akademi University. The most important finding has been that NH{sub 3} can be made to react selectively with the oxidizers even in the presence of large amounts of CO and H{sub 2}. Aluminium oxides were found to be the most effective materials promoting selectivity. (author)

The Saskatchewan Environmental Assessment Act Guide to Proposal Development : oil and natural gas projects

International Nuclear Information System (INIS)

1999-02-01

The manner in which requests for review of oil and natural gas projects are to be provided under the Environmental Assessment Act in Saskatchewan is described. The provisions of the Guide apply to all seismic projects on private or Crown lands, all drilling projects, flowline projects, access routes and production facilities on any land, except where the project is on cultivated land where it does not interfere with water bodies or endangered species. It also applies to any project that has the potential to meet the definition of 'development' under the Environmental Assessment Act. Basically, the following information is required for all proposals: (1) project description, (2) project evaluation, (3) description of proposed waste management practices, and (4) description of the proposed environmental monitoring. 4 refs

Inhibition of inducible Nitric Oxide Synthase by a mustard gas analog in murine macrophages

Directory of Open Access Journals (Sweden)

Smith Milton

2006-11-01

Full Text Available Abstract Background 2-Chloroethyl ethyl sulphide (CEES is a sulphur vesicating agent and an analogue of the chemical warfare agent 2,2'-dichlorodiethyl sulphide, or sulphur mustard gas (HD. Both CEES and HD are alkylating agents that influence cellular thiols and are highly toxic. In a previous publication, we reported that lipopolysaccharide (LPS enhances the cytotoxicity of CEES in murine RAW264.7 macrophages. In the present investigation, we studied the influence of CEES on nitric oxide (NO production in LPS stimulated RAW264.7 cells since NO signalling affects inflammation, cell death, and wound healing. Murine macrophages stimulated with LPS produce NO almost exclusively via inducible nitric oxide synthase (iNOS activity. We suggest that the influence of CEES or HD on the cellular production of NO could play an important role in the pathophysiological responses of tissues to these toxicants. In particular, it is known that macrophage generated NO synthesised by iNOS plays a critical role in wound healing. Results We initially confirmed that in LPS stimulated RAW264.7 macrophages NO is exclusively generated by the iNOS form of nitric oxide synthase. CEES treatment inhibited the synthesis of NO (after 24 hours in viable LPS-stimulated RAW264.7 macrophages as measured by either nitrite secretion into the culture medium or the intracellular conversion of 4,5-diaminofluorescein diacetate (DAF-2DA or dichlorofluorescin diacetate (DCFH-DA. Western blots showed that CEES transiently decreased the expression of iNOS protein; however, treatment of active iNOS with CEES in vitro did not inhibit its enzymatic activity Conclusion CEES inhibits NO production in LPS stimulated macrophages by decreasing iNOS protein expression. Decreased iNOS expression is likely the result of CEES induced alteration in the nuclear factor kappa B (NF-κB signalling pathway. Since NO can act as an antioxidant, the CEES induced down-regulation of iNOS in LPS

Tuning the Electron Gas at an Oxide Heterointerface via Free Surface Charges

Energy Technology Data Exchange (ETDEWEB)

Bell, Christopher

2011-08-11

Oxide heterointerfaces are emerging as one of the most exciting materials systems in condensed matter science. One remarkable example is the LaAlO{sub 3}/SrTiO{sub 3} (LAO/STO) interface, a model system in which a highly mobile electron gas forms between two band insulators, exhibiting two dimensional superconductivity and unusual magnetotransport properties. An ideal tool to tune such an electron gas is the electrostatic field effect. In principle, the electrostatic field can be generated by bound charges due to polarization (as in the normal and ferroelectric field effects) or by adding excess free charge. In previous studies, a large modulation of the carrier density and mobility of the LAO/STO interface has been achieved using the normal field effect. However, little attention has been paid to the field effect generated by free charges. This issue is scarcely addressed, even in conventional semiconductor devices, since the free charges are typically not stable. Here, we demonstrate an unambiguous tuning of the LAO/STO interface conductivity via free surface charges written using conducting atomic force microscopy (AFM). The modulation of the carrier density was found to be reversible, nonvolatile and surprisingly large, {approx}3 x 10{sup 13} cm{sup -2}, comparable to the maximum modulation by the normal field effect. Our finding reveal the efficiency of free charges in controlling the conductivity of this oxide interface, and suggest that this technique may be extended more generally to other oxide systems.

Dynamic measurement of mercury adsorption and oxidation on activated carbon in simulated cement kiln flue gas

DEFF Research Database (Denmark)

Zheng, Yuanjing; Jensen, Anker Degn; Windelin, Christian

2012-01-01

of the sulfite converter is short and typically within 2min. Dynamic mercury adsorption and oxidation tests on commercial activated carbons Darco Hg and HOK standard were performed at 150°C using simulated cement kiln gas and a fixed bed reactor system. It is shown that the converter and analyzer system...... are still under development and are investigated in this work. A commercial red brass converter was tested at 180°C and it was found that the red brass chips work in nitrogen atmosphere only, but do not work properly under simulated cement kiln flue gas conditions. Test of the red brass converter using only...... elemental mercury shows that when HCl is present with either SO2 or NOx the mercury measurement after the converter is unstable and lower than the elemental mercury inlet level. The conclusion is that red brass chips cannot fully reduce oxidized mercury to elemental mercury when simulated cement kiln gas...

Design study of shaft face seal with self-acting lift augmentation. 5: Performance in simulated gas turbine engine operation

Science.gov (United States)

Ludwig, L. P.; Johnson, R. L.

1971-01-01

The feasibility and the noncontact operation of the self-acting seal was demonstrated over a range of simulated gas turbine engine conditions from 200 to 500 ft/sec sliding speed. Sealed pressure differentials were 50 to 300 psi and sealed temperatures were 150 to 1200 F. Low leakage (about 1/10 that of conventional labyrinth seals) was exhibited in two endurance runs (200 and 338 hr) at 400 ft/sec, 200 psi and 1000 F (gas temperature). For these endurance runs, the self-acting pad wear was less than 3.8 micrometers (0.00015 in.); this low wear was attributed to the noncontact operation of the primary seal. Operating problems identified were fretting wear of the secondary seal and erosion of the primary seal by hard particles.

Methane oxidation over noble metal catalysts as related to controlling natural gas vehicle exhaust emissions

International Nuclear Information System (INIS)

Oh, S.H.; Mitchell, P.J.; Siewert, R.M.

1992-01-01

Natural gas has considerable potential as an alternative automotive fuel. This paper reports on methane, the principal hydrocarbon species in natural-gas engine exhaust, which has extremely low photochemical reactivity but is a powerful greenhouse gas. Therefore, exhaust emissions of unburned methane from natural-gas vehicles are of particular concern. This laboratory reactor study evaluates noble metal catalysts for their potential in the catalytic removal of methane from natural-gas vehicle exhaust. Temperature run-up experiments show that the methane oxidation activity decreases in the order Pd/Al 2 O 3 > Rh/Al 2 O 3 > Pt/Al 2 O 3 . Also, for all the noble metal catalysts studied, methane conversion can be maximized by controlling the O 2 concentration of the feedstream at a point somewhat rich (reducing) of stoichiometry

System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures

KAUST Repository

Ehrhart, Brian D.

2016-09-22

The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas-gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered. © 2016 Hydrogen Energy Publications LLC.

Solving widespread low-concentration VOC air pollution problems: Gas-phase photocatalytic oxidation answers the needs of many small businesses

Energy Technology Data Exchange (ETDEWEB)

Lyons, C; Turchi, C; Gratson, D

1995-04-01

Many small businesses are facing new regulations under the 1990 Amendments to the Clean Air Act. Regulators, as well as the businesses themselves, face new challenges to control small point-source air pollution emissions. An individual business-such as a dry cleaner, auto repair shop, bakery, coffee roaster, photo print shop, or chemical company-may be an insignificant source of air pollution, but collectively, the industry becomes a noticeable source. Often the businesses are not equipped to respond to new regulatory requirements because of limited resources, experience, and expertise. Also, existing control strategies may be inappropriate for these businesses, having been developed for major industries with high volumes, high pollutant concentrations, and substantial corporate resources. Gas-phase photocatalytic oxidation (PCO) is an option for eliminating low-concentration, low-flow-rate emissions of volatile organic compounds (VOCs) from small business point sources. The advantages PCO has over other treatment techniques are presented in this paper. This paper also describes how PCO can be applied to specific air pollution problems. We present our methodology for identifying pollution problems for which PCO is applicable and for reaching the technology`s potential end users. PCO is compared to other gas-phase VOC control technologies.

Change of properties after oxidation of IG-11 graphite by air and CO2 gas

International Nuclear Information System (INIS)

Lim, Yun-Soo; Chi, Se-Hwan; Cho, Kwang-Yun

2008-01-01

Artificial graphite is typically manufactured by carbonization of a shaped body of a kneaded mixture using granular cokes as a filler and pitch as a binder. It undergoes a pitch impregnation process if necessary and finally applying graphitization heat treatment. The effect of thermal oxidation in air or a CO 2 atmosphere on IG-11 graphite samples is investigated in this study. The results show a localized oxidation process that progressively reveals the large coke particles with increasing level of overall weight loss in air. The surface of the graphite was peeled off and no change was found in the specific gravity after air oxidation. However, the specific gravity of graphite was continuously decreased by CO 2 oxidation. The decrease in the specific gravity by CO 2 oxidation was due to CO 2 gas that progressed from the surface to the interior. The pore shape after CO 2 oxidation differed from that under air oxidation

Gas dusulfurization

International Nuclear Information System (INIS)

Powell, B.E.; Bakhshi, V.S.; Randolph, D.A.

1984-01-01

A process for adsorbing sulfur dioxide from a gas comprising contacting a gas containing SO 2 , such as a flue gas, with about stoichiometric amounts of a specially prepared calcium oxide so that substantially all of the sulfur dioxide content is reacted throughout the calcium oxide particle to form a calcium sulfate reaction product. The useful calcium oxide particles comprise a highly voided skeletal structure of very large surface area and large pore volume with numerous macro pores. Such particles are obtained by flash calcining sand-size grains of calcium carbonate, such as aragonite, calcite or dolomite

Tungsten oxide coatings deposited by plasma spray using powder and solution precursor for detection of nitrogen dioxide gas

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chao, E-mail: zhangc@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Wang, Jie [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Geng, Xin [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

2016-05-25

Increasing attention has been paid on preparation methods for resistive-type gas sensors based on semiconductor metal oxides. In this work, tungsten oxide (WO{sub 3}) coatings were prepared on alumina substrates and used as gas sensitive layers. The coatings were deposited by atmospheric plasma spray using powder, solution precursor, or a combination of both. Tungsten oxide powder through a powder port and ammonium tungstate aqueous solution through a liquid port were injected into plasma stream respectively or together to deposit WO{sub 3} coatings. Phase structures in the coatings were characterized by X-ray diffraction analyzer. The field-emission scanning electron microscopy images confirmed that the coatings were in microstructure, nanostructure or micro-nanostructure. The sensing properties of the sensors based on the coatings exposed to 1 ppm nitrogen dioxide gas were characterized in a home-made instrument. Sensing properties of the coatings were compared and discussed. The influences of gas humidity and working temperature on the sensor responses were further studied. - Highlights: • Porous gas sensitive coatings were deposited by plasma spray using powder and solution precursor. • Crystallized WO{sub 3} were obtained through hybrid plasma spray plus a pre-conditioned step. • Plasma power had an important influence on coating microstructure. • The particle size of atmospheric plasma-sprayed microstructured coating was stable. • Solution precursor plasma-sprayed WO{sub 3} coatings had nanostructure and showed good responses to 1 ppm NO{sub 2}.

Colonic production of nitric oxide gas in ulcerative colitis, collagenous colitis and uninflamed bowel

DEFF Research Database (Denmark)

Perner, Anders; Lassen, Inge Nordgaard; Matzen, Peter

2002-01-01

BACKGROUND: Nitric oxide (NO) produced in excess by the inflamed human colon is generally considered a pathway of mucosal damage. In an attempt to quantify colonic mucosal production of NO in various forms of colitis we performed 'steady-state' gas perfusion of whole colon in 11 patients...... by neutron activation analysis and the chemiluminescence technique, respectively. RESULTS: The use of argon as a marker of colonic NO output was justified by complete recovery (96%+/-2; mean +/- s(x); n = 5) of argon in gas collected from the rectum and a constant output of NO at varying perfusion rates (25...... higher (P gas perfusion of whole colon using chemiluminescence technique for measurement of NO is a reliable method...

Gas-exfoliated porous monolayer boron nitride for enhanced aerobic oxidative desulfurization performance

Science.gov (United States)

Wu, Yingcheng; Wu, Peiwen; Chao, Yanhong; He, Jing; Li, Hongping; Lu, Linjie; Jiang, Wei; Zhang, Beibei; Li, Huaming; Zhu, Wenshuai

2018-01-01

Hexagonal boron nitride has been regarded to be an efficient catalyst in aerobic oxidation fields, but limited by the less-exposed active sites. In this contribution, we proposed a simple green liquid nitrogen gas exfoliation strategy for preparation of porous monolayer nanosheets (BN-1). Owing to the reduced layer numbers, decreased lateral sizes and artificially-constructed pores, increased exposure of active sites was expected, further contributed to an enhanced aerobic oxidative desulfurization (ODS) performance up to ˜98% of sulfur removal, achieving ultra-deep desulfurization. This work not only introduced an excellent catalyst for aerobic ODS, but also provided a strategy for construction of some other highly-efficient monolayer two-dimensional materials for enhanced catalytic performance.

Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion

OpenAIRE

Lawton, Thomas J.; Rosenzweig, Amy C.

2016-01-01

Biological conversion of natural gas to liquids (Bio-GTL) represents an immense economic opportunity. In nature, aerobic methanotrophic bacteria and anaerobic archaea are able to selectively oxidize methane using methane monooxygenase (MMO) and methyl coenzyme M reductase (MCR) enzymes. Although significant progress has been made toward genetically manipulating these organisms for biotechnological applications, the enzymes themselves are slow, complex, and not recombinantly tractable in tradi...

Highly selective gas sensor arrays based on thermally reduced graphene oxide.

Science.gov (United States)

Lipatov, Alexey; Varezhnikov, Alexey; Wilson, Peter; Sysoev, Victor; Kolmakov, Andrei; Sinitskii, Alexander

2013-06-21

The electrical properties of reduced graphene oxide (rGO) have been previously shown to be very sensitive to surface adsorbates, thus making rGO a very promising platform for highly sensitive gas sensors. However, poor selectivity of rGO-based gas sensors remains a major problem for their practical use. In this paper, we address the selectivity problem by employing an array of rGO-based integrated sensors instead of focusing on the performance of a single sensing element. Each rGO-based device in such an array has a unique sensor response due to the irregular structure of rGO films at different levels of organization, ranging from nanoscale to macroscale. The resulting rGO-based gas sensing system could reliably recognize analytes of nearly the same chemical nature. In our experiments rGO-based sensor arrays demonstrated a high selectivity that was sufficient to discriminate between different alcohols, such as methanol, ethanol and isopropanol, at a 100% success rate. We also discuss a possible sensing mechanism that provides the basis for analyte differentiation.

Intelligent Design of Metal Oxide Gas Sensor Arrays Using Reciprocal Kernel Support Vector Regression

Science.gov (United States)

Dougherty, Andrew W.

Metal oxides are a staple of the sensor industry. The combination of their sensitivity to a number of gases, and the electrical nature of their sensing mechanism, make the particularly attractive in solid state devices. The high temperature stability of the ceramic material also make them ideal for detecting combustion byproducts where exhaust temperatures can be high. However, problems do exist with metal oxide sensors. They are not very selective as they all tend to be sensitive to a number of reduction and oxidation reactions on the oxide's surface. This makes sensors with large numbers of sensors interesting to study as a method for introducing orthogonality to the system. Also, the sensors tend to suffer from long term drift for a number of reasons. In this thesis I will develop a system for intelligently modeling metal oxide sensors and determining their suitability for use in large arrays designed to analyze exhaust gas streams. It will introduce prior knowledge of the metal oxide sensors' response mechanisms in order to produce a response function for each sensor from sparse training data. The system will use the same technique to model and remove any long term drift from the sensor response. It will also provide an efficient means for determining the orthogonality of the sensor to determine whether they are useful in gas sensing arrays. The system is based on least squares support vector regression using the reciprocal kernel. The reciprocal kernel is introduced along with a method of optimizing the free parameters of the reciprocal kernel support vector machine. The reciprocal kernel is shown to be simpler and to perform better than an earlier kernel, the modified reciprocal kernel. Least squares support vector regression is chosen as it uses all of the training points and an emphasis was placed throughout this research for extracting the maximum information from very sparse data. The reciprocal kernel is shown to be effective in modeling the sensor

Expansion of the acceptance program: nitrous oxide scavenging equipment and nitrous oxide trace gas monitoring equipment

Energy Technology Data Exchange (ETDEWEB)

1977-10-01

The Acceptance Program for dental materials and devices and the general guidelines for submission of products have been reported in the Journal (88:615 March 1974). At its April 1977 meeting, the Council included equipment for scavenging and monitoring trace nitrous oxide gas in its Acceptance Program. The Council has established the effective date for classification of products under these two sets of guidelines as one year from the date of publication of this announcement. After that date, classification of a product will be required before promotion or exhibition in Association media.

The Effect of the Concentration of Oxidant, Cr(VI), on the Iron Oxidation in Saline Water

Science.gov (United States)

Ahn, H.; Jo, H. Y.; Ryu, J. H.; Koh, Y. K.

2014-12-01

Deep geological disposal is currently considered as the most appropriate method to isolate high level radioactive wastes (HLRWs) from the ecosystem. If groundwater seeps into underground disposal facilities, water molecules can be dissociated to radicals or peroxides, which can oxidize metal canisters and HLRWs. The oxidized radionuclides with a high solubility can be dissolved in the groundwater. Some dissolved radionuclides can act as oxidants. The continuous radiolysis of water molecules, which results from continuous seepage of groundwater, can enable the continuous production of the radioactive oxidants, resulting in an increase in concentration of oxidants. In this study, the effect of oxidant concentration on iron oxidation in the presence of salt was evaluated. Zero valent iron (ZVI) particles were reacted with Cr(VI) solutions with initial Cr(VI) concentrations ranged from 50 to 300 mg/L in reactors. The initial pH and NaCl concentration were fixed at 3 and 0.5 M, respectively. An increase in the initial Cr(VI) concentration caused an increase in the rate and extend of H2 gas production. The decrement of Cr(VI) was increased as the initial Cr(VI) concentration was increased. The penetration of H+ ions in the presence Cl- ions through the passive film on the ZVI particles caused the reaction between H+ ions and ZVI particles, producing H2 gas and Fe2+ ions. The passive film was damaged during the reaction due to the eruption of H2 gas or peptization by Cl- ions. The Fe2+ ions were reacted with Cr(VI) ions in the solution, producing Fe(III)-Cr(III) (oxy)hydroxides on the passive film of ZVI particles or in the solution as colloidal particles. The Fe(III)-Cr(III) (oxy)hydroxides tends to be precipitated as colloidal particles at a high Cr(VI) concentration and precipitated on the passive film at a low Cr(VI) concentration. The passive film was repaired or thickened by additional formation of Fe(III)-Cr(III) (oxy)hydroxides at a lower Cr(VI) concentration.

PALLADIUM DOPED TIN OXIDE BASED HYDROGEN GAS SENSORS FOR SAFETY APPLICATIONS

International Nuclear Information System (INIS)

Kasthurirengan, S.; Behera, Upendra; Nadig, D. S.

2010-01-01

Hydrogen is considered to be a hazardous gas since it forms a flammable mixture between 4 to 75% by volume in air. Hence, the safety aspects of handling hydrogen are quite important. For this, ideally, highly selective, fast response, small size, hydrogen sensors are needed. Although sensors based on different technologies may be used, thin-film sensors based on palladium (Pd) are preferred due to their compactness and fast response. They detect hydrogen by monitoring the changes to the electrical, mechanical or optical properties of the films. We report the development of Pd-doped tin-oxide based gas sensors prepared on thin ceramic substrates with screen printed platinum (Pt) contacts and integrated nicrome wire heaters. The sensors are tested for their performances using hydrogen-nitrogen gas mixtures to a maximum of 4%H 2 in N 2 . The sensors detect hydrogen and their response times are less than a few seconds. Also, the sensor performance is not altered by the presence of helium in the test gas mixtures. By the above desired performance characteristics, field trials of these sensors have been undertaken. The paper presents the details of the sensor fabrication, electronic circuits, experimental setup for evaluation and the test results.

Interfacial-Bonding-Regulated CO Oxidation over Pt Atoms Immobilized on Gas-Exfoliated Hexagonal Boron Nitride

KAUST Repository

Liu, Xin; Zhu, Hongdan; Linguerri, Roberto; Han, Yu; Chambaud, Gilberte; Meng, Changgong

2017-01-01

We compared the electronic structure and CO oxidation mechanisms over Pt atoms immobilized by both B-vacancies and N-vacancies on gas-exfoliated hexagonal boron nitride. We showed that chemical bonds are formed between the B atoms associated

Fiber optic hydrogen gas sensor utilizing surface plasmon resonance and native defects of zinc oxide by palladium

International Nuclear Information System (INIS)

Tabassum, Rana; Gupta, Banshi D

2016-01-01

We present an experimental study on a surface plasmon resonance (SPR) based fiber optic hydrogen gas sensor employing a palladium doped zinc oxide nanocomposite (ZnO (1−x) Pd x , 0 ≤ x ≤ 0.85) layer over the silver coated unclad core of the fiber. Palladium doped zinc oxide nanocomposites (ZnO (1−x) Pd x )  are prepared by a chemical route for different composition ratios and their structural, morphological and hydrogen sensing properties are investigated experimentally. The sensing principle involves the absorption of hydrogen gas by ZnO (1−x) Pd x , altering its dielectric function. The change in the dielectric constant is analyzed in terms of the red shift of the resonance wavelength in the visible region of the electromagnetic spectrum. To check the sensing capability of sensing probes fabricated with varying composition ratio (x) of nanocomposite, the SPR curves are recorded typically for 0% H 2 and 4% H 2 in N 2 atmosphere for each fabricated probe. On changing the concentration of hydrogen gas from 0% to 4%, the red shift in the SPR spectrum confirms the change in dielectric constant of ZnO (1−x) Pd x on exposure to hydrogen gas. It is noted that the shift in the SPR spectrum increases monotonically up to a certain fraction of Pd in zinc oxide, beyond which it starts decreasing. SEM images and the photoluminescence (PL) spectra reveal that Pd dopant atoms substitutionally incorporated into the ZnO lattice profoundly affect its defect levels; this is responsible for the optimal composition of ZnO (1−x) Pd x to sense the hydrogen gas. The sensor is highly selective to hydrogen gas and possesses high sensitivity. Since optical fiber sensing technology is employed along with the SPR technique, the present sensor is capable of remote sensing and online monitoring of hydrogen gas. (paper)

Study of the oxidation mechanisms between impurities and surfaces applied to the future gas-cooled nuclear reactors

International Nuclear Information System (INIS)

Duval, A.

2010-01-01

Inconel 617, main candidate for the heat exchangers of the gas-cooled next generation of nuclear reactors has been investigated. Two different problems occurring in the cooling system splits the study into two parts. Oxidizing impurities contained in the coolant can cause severe corrosion at 850 C. Radioactive impurities, coming from the fission reaction of the core can, in another hand contaminate the cooling loop and cause radioprotection problem for the maintenance and dismantling operations. Firstly, oxidizing gas partial pressure influence on oxidation of IN 617 at 850 C was investigated varying oxygen and water vapour partial pressure between 1.10 -5 mbar and 200 mbar. Oxide layers were characterized using XPS, SEM, EDX, GD-OES, XRD. Influence of partial pressure on layers structure and composition was determined. Effect of water vapour and partial pressure on growth mechanisms were also investigated. The second part of this study is focused on diffusion of Ag, stable isotope of Ag-110m in IN617 alloy and in the oxide layer forming at its surface at 850 C. Concentration profiles were obtained by GD-OES calibrated analysis. Diffusion coefficient could be obtained from these diffusion profiles: volume diffusion and grain boundary diffusion coefficients for the diffusion in the alloy, and an apparent diffusion coefficient for the diffusion in the oxide, due to the porosity of the structure. (author) [fr

Thin-film transistors with a channel composed of semiconducting metal oxide nanoparticles deposited from the gas phase

International Nuclear Information System (INIS)

Busch, C.; Schierning, G.; Theissmann, R.; Nedic, A.; Kruis, F. E.; Schmechel, R.

2012-01-01

The fabrication of semiconducting functional layers using low-temperature processes is of high interest for flexible printable electronics applications. Here, the one-step deposition of semiconducting nanoparticles from the gas phase for an active layer within a thin-film transistor is described. Layers of semiconducting nanoparticles with a particle size between 10 and 25 nm were prepared by the use of a simple aerosol deposition system, excluding potentially unwanted technological procedures like substrate heating or the use of solvents. The nanoparticles were deposited directly onto standard thin-film transistor test devices, using thermally grown silicon oxide as gate dielectric. Proof-of-principle experiments were done deploying two different wide-band gap semiconducting oxides, tin oxide, SnO x , and indium oxide, In 2 O 3 . The tin oxide spots prepared from the gas phase were too conducting to be used as channel material in thin-film transistors, most probably due to a high concentration of oxygen defects. Using indium oxide nanoparticles, thin-film transistor devices with significant field effect were obtained. Even though the electron mobility of the investigated devices was only in the range of 10 −6 cm 2V−1s−1 , the operability of this method for the fabrication of transistors was demonstrated. With respect to the possibilities to control the particle size and layer morphology in situ during deposition, improvements are expected.

Slovak Republic Act of 11 February 1998 on the energetics and on alterations to Act No. 455/1991 Collection of Acts of CSFR on small business (trade Act) in version of posterior regulations

International Nuclear Information System (INIS)

1998-01-01

This act constitute: (a) conditions of undertaking in electro-energetic, gas industry, and heat supply (in next only 'energetic' branches) ; (b) rights and responsibility of physical and act person undertaking in energetic branches; (c) rights and responsibility of customers of electricity, gas, and heat; counteract measures in the need situations, (d) and at prevention before need situations in energetic branches; (e) state regulation in energetic; (f) authority on keep of this act. The act is divided into for parts: (1) General constitutions, (2) Energetic branches; (3) The state authority; (4) Common, transient and invalidation constitutions.This act deals with the specific conditions for undertaking in nuclear power plants, too (licensing, security). This act shall into effect on 1 July 1998

Solid gas reaction phase diagram under high gas pressure

International Nuclear Information System (INIS)

Ishizaki, K.

1992-01-01

This paper reports that to evaluate which are the stable phases under high gas pressure conditions, a solid-gas reaction phase diagram under high gas pressure (HIP phase diagram) has been proposed by the author. The variables of the diagram are temperature, reactant gas partial pressure and total gas pressure. Up to the present time the diagrams have been constructed using isobaric conditions. In this work, the stable phases for a real HIP process were evaluated assuming an isochoric condition. To understand the effect of the total gas pressure on stability is of primary importance. Two possibilities were considered and evaluated, those are: the total gas pressure acts as an independent variable, or it only affects the fugacity values. The results of this work indicate that the total gas pressure acts as an independent variable, and in turn also affects the fugacity values

Pre-reforming of natural gas in solid oxide fuel-cell systems

Energy Technology Data Exchange (ETDEWEB)

Peters, R.; Riensche, E.; Cremer, P. [Institute for Materials and Processes Systems IWV 3: Energy Process Engineering, Forschungszentrum Juelich (Germany)

2000-03-01

Several measures concerning fuel processing in a solid oxide fuel cell (SOFC) system offer the possibility of significant cost reduction and higher system efficiencies. For SOFC systems, the ratio between internal and pre-reforming has to be optimized on the basis of experimental performance data. Furthermore, anode gas recycling by an injector in front of the pre-reformer can eliminate the steam generator and the corresponding heat of evaporation. A detailed study is carried out on pre-reforming in a reformer of considerable size (10 kW{sub el}). Simulating anode gas recycling with an injector, the influence of carbon dioxide on reactor performance was studied. Also, the dependence of the methanol conversion on mass flow and temperature will be discussed. In addition, some results concerning the dynamic behaviour of the pre-reformer are given. (orig.)

Kinetics of the gas-phase tritium oxidation reaction

International Nuclear Information System (INIS)

Failor, R.A.

1989-01-01

Homogeneous gas-phase kinetics of tritium oxidation (2T 2 + O 2 →2T 2 O) have been studied with a model that accounts explicitly for radiolysis of the major species and the kinetics of the subsequent reactions of ionic, excited-state, and neutral species. Results from model calculations are given for 10 -4 -1.0 mol% T 2 in O 2 (298 K, 1 atm). As the reaction evolves three different mechanisms control T 2 O production, each with a different overall rate expression and a different order with respect to the T 2 concentration. The effects of self-radiolysis of pure T 2 on the tritium oxidation reaction were calculated. Tritium atoms, the primary product of T 2 self-radiolysis, altered the oxidation mechanism only during the first few seconds following the initiation of the T 2 -O 2 reaction. Ozone, an important intermediate in T 2 oxidation, was monitored in-situ by U.V. absorption spectroscopy for 0.01-1.0 mol% T 2 an 1 atm O 2 . The shape of the experimental ozone time profile agreed with the model predictions. As predicted, the measured initial rate of ozone production varied linearly with initial T 2 concentration ([T 2 ] 0.6 o ), but at an initial rate one-third the predicted value. The steady-state ozone concentration ([O 3 ]ss) was predicted to be dependent on [T 2 ] 0.3 o , but the measured value was [T 2 ] 0.6 o , resulting in four times higher [O 3 ]ss than predicted for a 1.0% T 2 -O 2 mixture. Adding H 2 to the T 2 -O 2 mixture, to provide insight into the differences between the radiolytic and chemical behavior of the tritium, produced a greater decrease in [O 3 ]ss than predicted. Adjusting the reaction cell surface-to-volume ratio showed implications of minor surface removal of ozone

Gas replacement system for fuel cell. Nenryo denchi no gas chikan hoshiki

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, T

1990-02-14

When stopping the operation of a fuel cell, the gas in the reaction gas system is purged using such an inert gas as nitrogen for inactivation. A gas source such as inert gas bomb must be prepared beforehand for the purpose. This invention relates to a method of production of inert gas from the air collected from atmosphere to use it as the purge gas. The air collected from the atmosphere is passed through an oxygen remover filled with oxidation catalyst to remove oxygen, and dehumidified by a dehumidifier filled with drying agent, the obtained inert drying gas with nitrogen as the main constituent being used as the purge gas. Copper system catalyst supported by silica is used as the oxidation catalyst, and silica gel as the drying agent. After the operation of the fuel cell is re-started, a part of the high temperature fuel gas extracted from the reaction gas system is introduced to the oxygen remover for the reduction of oxidation catalyst and for heat regeneration of dehumidifying agent by the contained hydrogen. 1 fig.

On-chip growth of semiconductor metal oxide nanowires for gas sensors: A review

Directory of Open Access Journals (Sweden)

Chu Manh Hung

2017-09-01

Full Text Available Semiconductor metal oxide nanowires (SMO-NWs show great potential for novel gas sensor applications because of their distinct properties, such as a high surface area to volume aspect ratio, high crystallinity and perfect pathway for electron transfer (length of NW. SMO-NW sensors can be configured as resistors or field-effect transistors for gas detection and different configurations, such as a single NW, multiple NWs, and networked NW films, have been established. Surface-functionalizing NWs with catalyst elements and self-heating NWs provide additional advantages for highly selective and low-power consumption gas sensors. However, an appropriate design of SMO-NWs is of practical importance in enhancing the gas-sensing performance of SMO-NW sensors. The on-chip growth of SMO-NWs possesses many advantages which can thus be effectively used for the large-scale fabrication of SMO-NW sensors with improved gas response and stability. This review aims to provide up-to-date information on the on-chip fabrication of SnO2, ZnO, WO3, CuO, and other SMO-NW sensors. It also discusses a variety of promising approaches that help advance the on-chip fabrication of SMO-NW-based gas sensors and other NW-based devices.

STUDY OF THE EFFECT OF CHLORINE ADDITION ON MERCURY OXIDATION BY SCR CATALYST UNDER SIMULATED SUBBITUMINOUS COAL FLUE GAS

Science.gov (United States)

An entrained flow reactor is used to study the effect of addition of chlorine-containing species on the oxidation of elemental mercury (Hgo)by a selective catalytic reduction (SCR) catalyst in simulated subbituminous coal combustion flue gas. The combustion flue gas was doped wit...

Reducibility of ceria-lanthana mixed oxides under temperature programmed hydrogen and inert gas flow conditions

International Nuclear Information System (INIS)

Bernal, S.; Blanco, G.; Cifredo, G.; Perez-Omil, J.A.; Pintado, J.M.; Rodriguez-Izquierdo, J.M.

1997-01-01

The present paper deals with the preparation and characterization of La/Ce mixed oxides, with La molar contents of 20, 36 and 57%. We carry out the study of the structural, textural and redox properties of the mixed oxides, comparing our results with those for pure ceria. For this aim we use temperature programmed reduction (TPR), temperature programmed desorption (TPD), nitrogen physisorption at 77 K, X-ray diffraction and high resolution electron microscopy. The mixed oxides are more easy to reduce in a flow of hydrogen than ceria. Moreover, in an inert gas flow they release oxygen in higher amounts and at lower temperatures than pure CeO 2 . The textural stability of the mixed oxides is also improved by incorporation of lanthana. All these properties make the ceria-lanthana mixed oxides interesting alternative candidates to substitute ceria in three-way catalyst formulations. (orig.)

Plasmachemical oxidation processes in a hybrid gas-liquid electrical discharge reactor

Energy Technology Data Exchange (ETDEWEB)

Lukes, Petr; Locke, Bruce R [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, Florida (United States)

2005-11-21

Oxidation processes induced in water by pulsed electrical discharges generated simultaneously in the gas phase in close proximity to the water surface and directly in the liquid were investigated in a hybrid series gas-liquid electrical discharge reactor. The mechanism of phenol degradation was studied through its dependence on the gas phase and liquid phase compositions using pure argon and oxygen atmospheres above the liquid and different initial pH values in the aqueous solution. Phenol degradation was significantly enhanced in the hybrid-series reactor compared with the phenol removal by the single-liquid phase discharge reactor. Under an argon atmosphere the mechanism of phenol degradation was mainly caused by the electrophilic attack of OH{center_dot} radicals produced by the liquid phase discharge directly in water and OH{center_dot} radicals produced by the gas phase discharge at the gas-liquid interface. Under an oxygen atmosphere the formation of gaseous ozone dominated over the formation of OH{center_dot} radicals, and the contribution of the gas phase discharge in this case was determined mainly by the dissolution of gaseous ozone into the water and its subsequent interaction with phenol. At high pH phenol was degraded, in addition to the direct attack by ozone, also through indirect reactions of OH{center_dot} radicals formed via a peroxone process by the decomposition of dissolved ozone by hydrogen peroxide produced by the liquid phase discharge. Such a mechanism was proved by the detection of cis,cis-muconic acid and pH-dependent degradation of phenol, which resulted in significantly higher removal of phenol from alkaline solution observed under oxygen atmosphere than in argon.

Plasmachemical oxidation processes in a hybrid gas-liquid electrical discharge reactor

International Nuclear Information System (INIS)

Lukes, Petr; Locke, Bruce R

2005-01-01

Oxidation processes induced in water by pulsed electrical discharges generated simultaneously in the gas phase in close proximity to the water surface and directly in the liquid were investigated in a hybrid series gas-liquid electrical discharge reactor. The mechanism of phenol degradation was studied through its dependence on the gas phase and liquid phase compositions using pure argon and oxygen atmospheres above the liquid and different initial pH values in the aqueous solution. Phenol degradation was significantly enhanced in the hybrid-series reactor compared with the phenol removal by the single-liquid phase discharge reactor. Under an argon atmosphere the mechanism of phenol degradation was mainly caused by the electrophilic attack of OH· radicals produced by the liquid phase discharge directly in water and OH· radicals produced by the gas phase discharge at the gas-liquid interface. Under an oxygen atmosphere the formation of gaseous ozone dominated over the formation of OH· radicals, and the contribution of the gas phase discharge in this case was determined mainly by the dissolution of gaseous ozone into the water and its subsequent interaction with phenol. At high pH phenol was degraded, in addition to the direct attack by ozone, also through indirect reactions of OH· radicals formed via a peroxone process by the decomposition of dissolved ozone by hydrogen peroxide produced by the liquid phase discharge. Such a mechanism was proved by the detection of cis,cis-muconic acid and pH-dependent degradation of phenol, which resulted in significantly higher removal of phenol from alkaline solution observed under oxygen atmosphere than in argon

Analysis of a gas-liquid film plasma reactor for organic compound oxidation

Energy Technology Data Exchange (ETDEWEB)

Hsieh, Kevin [Department of Chemical and Biomedical Engineering, Florida State University, Tallahassee, FL 32310 (United States); Wang, Huijuan [School of Environmental and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China); Locke, Bruce R., E-mail: blocke@fsu.edu [Department of Chemical and Biomedical Engineering, Florida State University, Tallahassee, FL 32310 (United States)

2016-11-05

Highlights: • Non-homogeneous filamentary plasma discharge formed along gas-liquid interface. • Hydrogen peroxide formed near interface favored over organic oxidation from liquid. • Post-plasma Fenton reactions lead to complete utilization of hydrogen peroxide. - Abstract: A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas and a liquid water film was analyzed using methylene blue as a liquid phase hydroxyl radical scavenger and simultaneous measurements of hydrogen peroxide formation. The effects of liquid flow rate, liquid conductivity, concentration of dye, and the addition of ferrous ion on dye decoloration and degradation were determined. Higher liquid flow rates and concentrations of dye resulted in less decoloration percentages and hydrogen peroxide formation due to initial liquid conductivity effects and lower residence times in the reactor. The highest decoloration energy yield of dye found in these studies was 5.2 g/kWh when using the higher liquid flow rate and adding the catalyst. The non-homogeneous nature of the plasma discharge favors the production of hydrogen peroxide in the plasma-liquid interface over the chemical oxidation of the organic in the bulk liquid phase and post-plasma reactions with the Fenton catalyst lead to complete utilization of the plasma-formed hydrogen peroxide.

Functionalised zinc oxide nanowire gas sensors: Enhanced NO(2) gas sensor response by chemical modification of nanowire surfaces.

Science.gov (United States)

Waclawik, Eric R; Chang, Jin; Ponzoni, Andrea; Concina, Isabella; Zappa, Dario; Comini, Elisabetta; Motta, Nunzio; Faglia, Guido; Sberveglieri, Giorgio

2012-01-01

Surface coating with an organic self-assembled monolayer (SAM) can enhance surface reactions or the absorption of specific gases and hence improve the response of a metal oxide (MOx) sensor toward particular target gases in the environment. In this study the effect of an adsorbed organic layer on the dynamic response of zinc oxide nanowire gas sensors was investigated. The effect of ZnO surface functionalisation by two different organic molecules, tris(hydroxymethyl)aminomethane (THMA) and dodecanethiol (DT), was studied. The response towards ammonia, nitrous oxide and nitrogen dioxide was investigated for three sensor configurations, namely pure ZnO nanowires, organic-coated ZnO nanowires and ZnO nanowires covered with a sparse layer of organic-coated ZnO nanoparticles. Exposure of the nanowire sensors to the oxidising gas NO(2) produced a significant and reproducible response. ZnO and THMA-coated ZnO nanowire sensors both readily detected NO(2) down to a concentration in the very low ppm range. Notably, the THMA-coated nanowires consistently displayed a small, enhanced response to NO(2) compared to uncoated ZnO nanowire sensors. At the lower concentration levels tested, ZnO nanowire sensors that were coated with THMA-capped ZnO nanoparticles were found to exhibit the greatest enhanced response. ΔR/R was two times greater than that for the as-prepared ZnO nanowire sensors. It is proposed that the ΔR/R enhancement in this case originates from the changes induced in the depletion-layer width of the ZnO nanoparticles that bridge ZnO nanowires resulting from THMA ligand binding to the surface of the particle coating. The heightened response and selectivity to the NO(2) target are positive results arising from the coating of these ZnO nanowire sensors with organic-SAM-functionalised ZnO nanoparticles.

Optimizing The Efficiency of a Dielectric Barrier Discharge Reactor for Removal of Nitric Oxides in Gas Phase

International Nuclear Information System (INIS)

Siti Aiasah Hashim; Wong, C.S.; Abas, M.R.

2016-01-01

A dielectric barrier discharge (DBD) reactor was built and used to remove nitric oxides in gas phase. In the preliminary work, it was found that the DBD reactor can used for direct processing of contaminated air stream. It was observed that if the applied energy is sufficiently high, reduction can overcome the oxidation process. The other characteristics that can affect the efficiency of the reactor are the processing flow rate, number of DBD tubes used and how the tubes are connected. The composition of the feed gas also plays important role. To improve the efficiency, more tubes were added and configured in combination of serial and parallel connections to achieve the best result. The reactor was found to be most efficient when using 6 tubes configured to have 2 sets of 3 tubes in series connected in parallel. The maximum flow rate that can be treated is 5 scfh. When operated with the optimum input voltage of 32 kV, the reactor can remove up to 80 % nitric oxide in the reduction mode. This means that the energy is sufficiently high to sustain the reduction mode and prevent further oxidation. (author)

Oxidation and Condensation of Zinc Fume From Zn-CO2-CO-H2O Streams Relevant to Steelmaking Off-Gas Systems

International Nuclear Information System (INIS)

Bronson, Tyler Mark; Ma, Naiyang; Zhu, Liang Zhu; Sohn, Hong Yong

2017-01-01

Here the objective of this research was to study the condensation of zinc vapor to metallic zinc and zinc oxide solid under varying environments to investigate the feasibility of in-process separation of zinc from steelmaking off-gas dusts. Water vapor content, temperature, degree of cooling, gas composition, and initial zinc partial pressure were varied to simulate the possible conditions that can occur within steelmaking off-gas systems, limited to Zn-CO 2 -CO-H 2 O gas compositions. The temperature of deposition and the effect of rapidly quenching the gas were specifically studied. A homogeneous nucleation model for applicable experiments was applied to the analysis of the experimental data. It was determined that under the experimental conditions, oxidation of zinc vapor by H 2 O or CO 2 does not occur above 1108 K (835 °C) even for highly oxidizing streams (CO 2 /CO = 40/7). Rate expressions that correlate CO 2 and H 2 O oxidation rates to gas composition, partial pressure of water vapor, temperature, and zinc partial pressure were determined to be as follows: Rate ((mol)/(m 2 s)) = 406 exp ((−50.2kJ/mol)/(RT)) (pZnpCO 2 − PCO/K eq CO 2 ) ((mol)/(m 2 xs)) Rate (((mol)/(m 2 s))) = 32.9 exp (((−13.7kJ/mol)/(RT))) (pZnPH 2 O − PH 2 /K eq H 2 O) ((mol)/(m 2 xs)). It was proven that a rapid cooling rate (500 K/s) significantly increases the ratio of metallic zinc to zinc oxide as opposed to a slow cooling rate (250 K/s). SEM analysis found evidence of heterogeneous growth of ZnO as well as of homogeneous formation of metallic zinc. The homogeneous nucleation model fit well with experiments where only metallic zinc deposited. An expanded model with rates of oxidation by CO 2 and H 2 O as shown was combined with the homogenous nucleation model and then compared with experimental data. The calculated results based on the model gave a reasonable fit to the measured data. For the conditions used in this study, the rate equations for the oxidation of zinc by

Calculation of gas-flow in plasma reactor for carbon partial oxidation

Science.gov (United States)

Bespala, Evgeny; Myshkin, Vyacheslav; Novoselov, Ivan; Pavliuk, Alexander; Makarevich, Semen; Bespala, Yuliya

2018-03-01

The paper discusses isotopic effects at carbon oxidation in low temperature non-equilibrium plasma at constant magnetic field. There is described routine of experiment and defined optimal parameters ensuring maximum enrichment factor at given electrophysical, gas-dynamic, and thermodymanical parameters. It has been demonstrated that at high-frequency generator capacity of 4 kW, supply frequency of 27 MHz and field density of 44 mT the concentration of paramagnetic heavy nuclei 13C in gaseous phase increases up to 1.78 % compared to 1.11 % for natural concentration. Authors explain isotopic effect decrease during plasmachemical separation induced by mixing gas flows enriched in different isotopes at the lack of product quench. With the help of modeling the motion of gas flows inside the plasma-chemical reactor based on numerical calculation of Navier-Stokes equation authors determine zones of gas mixing and cooling speed. To increase isotopic effects and proportion of 13C in gaseous phase it has been proposed to use quench in the form of Laval nozzle of refractory steel. The article represents results on calculation of optimal Laval Nozzle parameters for plasma-chemical reactor of chosen geometry of. There are also given dependences of quench time of products on pressure at the diffuser output and on critical section diameter. Authors determine the location of quench inside the plasma-chemical reactor in the paper.

Reaction scheme of partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia

NARCIS (Netherlands)

Zhu, J.J.; van Ommen, J.G.; Lefferts, Leonardus

2004-01-01

The partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia (YSZ) was studied with in situ FTIR and both steady-state and transient experiments. The four major products, CO, H2, CO2, and H2O, are primary products of CPOM over YSZ. Besides these major products and traces of

Detection of OH on photolysis of styrene oxide at 193 nm in gas phase

Science.gov (United States)

Kumar, Awadhesh; SenGupta, Sumana; Pushpa, K. K.; Naik, P. D.; Bajaj, P. N.

2006-10-01

Photodissociation of styrene oxide at 193 nm in gas phase generates OH, as detected by laser-induced fluorescence technique. Under similar conditions, OH was not observed from ethylene and propylene oxides, primarily because of their low absorption cross-sections at 193 nm. Mechanism of OH formation involves first opening of the three-membered ring from the ground electronic state via cleavage of either of two C sbnd O bonds, followed by isomerization to enolic forms of phenylacetaldehyde and acetophenone, and finally scission of the C sbnd OH bond of enols. Ab initio molecular orbital calculations support the proposed mechanism.

Oxidation damage evaluation by non-destructive method for graphite components in high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Shibata, Taiju; Tada, Tatsuya; Sumita, Junya; Sawa, Kazuhiro

2008-01-01

To develop non-destructive evaluation methods for oxidation damage on graphite components in High Temperature Gas-cooled Reactors (HTGRs), the applicability of ultrasonic wave and micro-indentation methods were investigated. Candidate graphites, IG-110 and IG-430, for core components of Very High Temperature Reactor (VHTR) were used in this study. These graphites were oxidized uniformly by air at 500degC. The following results were obtained from this study. (1) Ultrasonic wave velocities with 1 MHz can be expressed empirically by exponential formulas to burn-off, oxidation weight loss. (2) The porous condition of the oxidized graphite could be evaluated with wave propagation analysis with a wave-pore interaction model. It is important to consider the non-uniformity of oxidized porous condition. (3) Micro-indentation method is expected to determine the local oxidation damage. It is necessary to assess the variation of the test data. (author)

Reduction of nitrogen oxides from simulated exhaust gas by using plasma-catalytic process

International Nuclear Information System (INIS)

Mok, Young Sun; Koh, Dong Jun; Shin, Dong Nam; Kim, Kyong Tae

2004-01-01

Removal of nitrogen oxides (NO x ) using a nonthermal plasma reactor (dielectric-packed bed reactor) combined with monolith V 2 O 5 /TiO 2 catalyst was investigated. The effect of initial NO x concentration, feed gas flow rate (space velocity), humidity, and reaction temperature on the removal of NO x was examined. The plasma reactor used can be energized by either ac or pulse voltage. An attempt was made to utilize the electrical ignition system of an internal combustion engine as a high-voltage pulse generator for the plasma reactor. When the plasma reactor was energized by the electrical ignition system, NO was readily oxidized to NO 2 . Performance was as good as with ac energization. Increasing the fraction of NO 2 in NO x , which is the main role of the plasma reactor, largely enhanced the NO x removal efficiency. In the plasma-catalytic reactor, the increases in initial NO x concentration, space velocity (feed gas flow rate) and humidity lowered the NO x removal efficiency. However, the reaction temperature in the range up to 473 K did not significantly affect the NO x removal efficiency in the presence of plasma discharge

Quantitative and Qualitative Aspects of Gas-Metal-Oxide Mass Transfer in High-Temperature Confocal Scanning Laser Microscopy

Science.gov (United States)

Piva, Stephano P. T.; Pistorius, P. Chris; Webler, Bryan A.

2018-05-01

During high-temperature confocal scanning laser microscopy (HT-CSLM) of liquid steel samples, thermal Marangoni flow and rapid mass transfer between the sample and its surroundings occur due to the relatively small sample size (diameter around 5 mm) and large temperature gradients. The resulting evaporation and steel-slag reactions tend to change the chemical composition in the metal. Such mass transfer effects can change observed nonmetallic inclusions. This work quantifies oxide-metal-gas mass transfer of solutes during HT-CSLM experiments using computational simulations and experimental data for (1) dissolution of MgO inclusions in the presence and absence of slag and (2) Ca, Mg-silicate inclusion changes upon exposure of a Si-Mn-killed steel to an oxidizing gas atmosphere.

Sulfur Poisoning of the Water Gas Shift Reaction on Anode Supported Solid Oxide Fuel Cells

DEFF Research Database (Denmark)

Hagen, Anke

2013-01-01

resistance increased both in the high and low frequency region, which indicates a strong poisoning of the water gas shift reaction and thus a lack of hydrogen fuel in addition to the poisoning of the electrochemical hydrogen oxidation. All poisoning effects are reversible under the applied operating...

Analysis of Gas Leakage and Current Loss of Solid Oxide Fuel Cells by Screen Printing

DEFF Research Database (Denmark)

Jia, Chuan; Han, Minfang; Chen, Ming

2017-01-01

Two types of anode supported solid oxide fuel cell (SOFC) NiO-YSZ/YSZ/GDC/LSCF with the same structure and different manufacturing process were tested. Gas leakage was suspected for cells manufactured with screen printing technique. Effective leak current densities for both types of cells were...... calculated. Their performances of electrochemical impedance spectroscopy (EIS) were compared and distribution function of relaxation times (DRT) technique was also used to find the clue of gas leakage. Finally, thinning and penetrating holes were observed in electrolyte layer, which confirmed the occurrence...

Oxidation of urate by a therapeutic nitric oxide/air mixture

International Nuclear Information System (INIS)

Hicks, M.; Nguyen, L.; Day, R.; Rogers, P.

1996-01-01

Full text: Little is known about the potential toxicological consequences of therapeutic exposure of lung tissue to inhaled nitric oxide (NO). This route of administration is currently being successfully employed for the treatment of pulmonary hypertension and other lung pathologies including acute reperfusion injury in lung transplant patients. The toxicity of NO lies in its ability to act as an oxidant either in its own right or in concert with oxygen or with the superoxide free radical. One important interaction may be the reaction of these products with protective antioxidants in the lung epithelial lining fluid. One such antioxidant found in significant concentrations in both upper and lower airways is uric acid. In the present study, urate solutions (30μM) were exposed to a therapeutic concentration of NO gas, (35 ppm in air), for up to 90 minutes. Oxidative changes were followed spectrophotometrically and by HPLC. Significant loss of uric acid was observed with a concomitant formation of nitrite and allantoin, the stable oxidation product of NO and the major oxidation product of uric acid, respectively. No oxidation of urate was observed in the presence of air alone or when urate was incubated with nitrite. Uric acid oxidation could also be prevented by passing the NO / air stream through 10% KOH before the uric acid solution. This strategy removed trace amounts of higher oxides of nitrogen, (especially NO 2 ), from the NO / air stream. Thus, therapeutic inhalation of NO may deplete soluble antioxidants such as uric acid, especially during long-term chronic exposure unless care is taken to minimise formation of higher oxides of nitrogen

Photoluminescent properties of complex metal oxide nanopowders for gas sensing

Science.gov (United States)

Bovhyra, R. V.; Mudry, S. I.; Popovych, D. I.; Savka, S. S.; Serednytski, A. S.; Venhryn, Yu. I.

2018-03-01

This work carried out research on the features of photoluminescence of the mixed and complex metal oxide nanopowders (ZnO/TiO2, ZnO/SnO2, Zn2SiO4) in vacuum and gaseous ambient. The nanopowders were obtained using pulsed laser reactive technology. The synthesized nanoparticles were characterized by X-ray diffractometry, energy-dispersive X-ray analysis, and scanning and transmission electron microscopy analysis for their sizes, shapes and collocation. The influence of gas environment on the photoluminescence intensity was investigated. A change of ambient gas composition leads to a rather significant change in the intensity of the photoluminescence spectrum and its deformation. The most significant changes in the photoluminescent spectrum were observed for mixed ZnO/TiO2 nanopowders. This obviously is the result of a redistribution of existing centers of luminescence and the appearance of new adsorption centers of luminescence on the surface of nanopowders. The investigated nanopowders can be effectively used as sensing materials for the construction of the multi-component photoluminescent sensing matrix.

Surface water and atmospheric carbon dioxide and nitrous oxide observations by shipboard automated gas chromatography: Results from expeditions between 1977 and 1990

International Nuclear Information System (INIS)

Weiss, R.F.; Van Woy, F.A.; Salameh, P.K.; Sepanski, R.J.

1992-12-01

This document presents the results of surface water and atmospheric carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) measurements carried out by shipboard gas chromatography over the period 1977--1990. These data include results from 11 different oceanic surveys for a total of 41 expedition legs. Collectively, they represent a globally distributed sampling that includes locations in the Atlantic, Pacific, Indian, and Southern Oceans, as well as the Mediterranean and Red Seas. The measurements were made by an automated high-precision shipboard gas chromatographic system developed during the late 1970s and used extensively over the intervening years. This instrument measures CO 2 by flame ionization after quantitative reaction to methane in a stream of hydrogen. Nitrous oxide is measured by a separate electron capture detector. The chromatographic system measures 196 dry-gas samples a day, divided equally among the atmosphere, gas equilibrated with surface water, a low-range gas standard, and a high-range gas standard

Thermodynamic simulation of biomass gas steam reforming for a solid oxide fuel cell (SOFC system

Directory of Open Access Journals (Sweden)

A. Sordi

2009-12-01

Full Text Available This paper presents a methodology to simulate a small-scale fuel cell system for power generation using biomass gas as fuel. The methodology encompasses the thermodynamic and electrochemical aspects of a solid oxide fuel cell (SOFC, as well as solves the problem of chemical equilibrium in complex systems. In this case the complex system is the internal reforming of biomass gas to produce hydrogen. The fuel cell input variables are: operational voltage, cell power output, composition of the biomass gas reforming, thermodynamic efficiency, electrochemical efficiency, practical efficiency, the First and Second law efficiencies for the whole system. The chemical compositions, molar flows and temperatures are presented to each point of the system as well as the exergetic efficiency. For a molar water/carbon ratio of 2, the thermodynamic simulation of the biomass gas reforming indicates the maximum hydrogen production at a temperature of 1070 K, which can vary as a function of the biomass gas composition. The comparison with the efficiency of simple gas turbine cycle and regenerative gas turbine cycle shows the superiority of SOFC for the considered electrical power range.

Landfill gas: planning and regulation

International Nuclear Information System (INIS)

Nealon, T.

1991-01-01

There is no legislation in the UK that relates directly to landfill gas. However, various pieces of legislation do exist which control all aspects of landfill and therefore, indirectly, landfill gas. This legislation includes Planning Acts, The Control of Pollution Act, Health and Safety at Work Acts, and Public Health Acts, and affects landfill gas throughout the life of the site - from planning stage to long after the last load has been deposited and restoration has been carried out. Responsibility for ensuring compliance with these various Acts lies with a variety of Authorities, including Plannning Authorities, Waste Disposal Authorities, and Environmental Health Authorities. Responsibility for actual compliance with the Acts lies with the operator, for active sites, and the landowner in the case of closed sites. (author)

Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion.

Science.gov (United States)

Lawton, Thomas J; Rosenzweig, Amy C

2016-08-03

Biological conversion of natural gas to liquids (Bio-GTL) represents an immense economic opportunity. In nature, aerobic methanotrophic bacteria and anaerobic archaea are able to selectively oxidize methane using methane monooxygenase (MMO) and methyl coenzyme M reductase (MCR) enzymes. Although significant progress has been made toward genetically manipulating these organisms for biotechnological applications, the enzymes themselves are slow, complex, and not recombinantly tractable in traditional industrial hosts. With turnover numbers of 0.16-13 s(-1), these enzymes pose a considerable upstream problem in the biological production of fuels or chemicals from methane. Methane oxidation enzymes will need to be engineered to be faster to enable high volumetric productivities; however, efforts to do so and to engineer simpler enzymes have been minimally successful. Moreover, known methane-oxidizing enzymes have different expression levels, carbon and energy efficiencies, require auxiliary systems for biosynthesis and function, and vary considerably in terms of complexity and reductant requirements. The pros and cons of using each methane-oxidizing enzyme for Bio-GTL are considered in detail. The future for these enzymes is bright, but a renewed focus on studying them will be critical to the successful development of biological processes that utilize methane as a feedstock.

Oxidative stress and pathogenic attack in plants, studied by laser based photoacoustic trace gas detection

NARCIS (Netherlands)

Santosa, Ignatius Edi

2002-01-01

Photoacoustic detection has proven to be a sensitive method, which is suitable for trace gas measurement. In this thesis, we improved the photoacoustic detection system to measure new biologically interesting gases, ethane (C2H6) and nitric oxide (NO). A new design of grating holder is incorporated

Evaluation of disposal methods for oxidized FGD sludge

International Nuclear Information System (INIS)

Yu, W.C.

1992-01-01

The implementation of wet flue gas desulfurization - in response to the Clean Air Act of 1990 - will cause many power generators and state regulatory personnel to face important decisions on the disposal of large volumes of resultant solid waste. Even with the selection of forced oxidation technology, it is widely recognized that the vast majority of flue gas desulfurization by-products will be disposed. This paper analyzes the water quality issues associated with gypsum stacking, macroencapsulation of gypsum, and the stabilization/fixation of gypsum. Water quality issues include leachate quality, leachate generation, runoff management, and groundwater impact. The following analysis uses both field and literature data to measure the environmental impact of the three most discussed disposal options

Pyrite oxidation in unsaturated aquifer sediments. Reaction stoichiometry and rate of oxidation

DEFF Research Database (Denmark)

Andersen, Martin Søgaard; Larsen, Flemming; Postma, Diederik Jan

2001-01-01

The oxidation of pyrite (FeS2) contained in unsaturated aquifer sediment was studied by sediment incubation in gas impermeable polymer laminate bags. Reaction progress was followed over a period of nearly 2 months by monitoring the gas composition within the laminate bag. The gas phase in the inc......The oxidation of pyrite (FeS2) contained in unsaturated aquifer sediment was studied by sediment incubation in gas impermeable polymer laminate bags. Reaction progress was followed over a period of nearly 2 months by monitoring the gas composition within the laminate bag. The gas phase...... in the incubation bags became depleted in O2 and enriched in CO2 and N2 and was interpreted as due to pyrite oxidation in combination with calcite dissolution. Sediment incubation provides a new method to estimate low rates of pyrite oxidation in unsaturated zone aquifer sediments. Oxidation rates of up to 9.4â10......-10 mol FeS2/gâs are measured, and the rates are only weakly correlated with the sediment pyrite content. The reactivity of pyrite, including the inhibition by FeOOH layers formed on its surface, apparently has a major effect on the rate of oxidation. The code PHREEQC 2.0 was used to calculate...

Highly Efficient Gas-Phase Oxidation of Renewable Furfural to Maleic Anhydride over Plate Vanadium Phosphorus Oxide Catalyst.

Science.gov (United States)

Li, Xiukai; Ko, Jogie; Zhang, Yugen

2018-02-09

Maleic anhydride (MAnh) and its acids are critical intermediates in chemical industry. The synthesis of maleic anhydride from renewable furfural is one of the most sought after processes in the field of sustainable chemistry. In this study, a plate vanadium phosphorus oxide (VPO) catalyst synthesized by a hydrothermal method with glucose as a green reducing agent catalyzes furfural oxidation to MAnh in the gas phase. The plate catalyst-denoted as VPO HT -has a preferentially exposed (200) crystal plane and exhibited dramatically enhanced activity, selectivity and stability as compared to conventional VPO catalysts and other state-of-the-art catalytic systems. At 360 °C reaction temperature with air as an oxidant, about 90 % yield of MAnh was obtained at 10 vol % of furfural in the feed, a furfural concentration value that is much higher than those (<2 vol %) reported for other catalytic systems. The catalyst showed good long-term stability and there was no decrease in activity or selectivity for MAnh during the time-on-stream of 25 h. The high efficiency and catalyst stability indicate the great potential of this system for the synthesis of maleic anhydride from renewable furfural. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrical and optical properties of thin indium tin oxide films produced by pulsed laser ablation in oxygen or rare gas atmospheres

DEFF Research Database (Denmark)

Thestrup, B.; Schou, Jørgen; Nordskov, A.

1999-01-01

Films of indium tin oxide (ITO) have been produced in different background gases by pulsed laser deposition (PLD). The Films deposited in rare gas atmospheres on room temperature substrates were metallic, electrically conductive, but had poor transmission of visible light. For substrate temperatu......Films of indium tin oxide (ITO) have been produced in different background gases by pulsed laser deposition (PLD). The Films deposited in rare gas atmospheres on room temperature substrates were metallic, electrically conductive, but had poor transmission of visible light. For substrate...

75 FR 54621 - Transparency Provisions of Section 23 of the Natural Gas Act; Notice of Availability of Revised...

Science.gov (United States)

2010-09-08

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. RM07-10-002] Transparency Provisions of Section 23 of the Natural Gas Act; Notice of Availability of Revised Form No. 552 for eFiling August 31, 2010. On August 17, 2010, the Office of Management and Budget approved a revised Form No. 552...

Oxidation of nitrobenzene by ozone in the presence of faujasite zeolite in a continuous flow gas-liquid-solid reactor.

Science.gov (United States)

Reungoat, J; Pic, J S; Manéro, M H; Debellefontaine, H

2010-01-01

This work investigates the oxidation of nitrobenzene (NB) by ozone in the presence of faujasite zeolite. Experiments were carried out in a gas-liquid-solid reactor were ozone transfer and NB oxidation took place at the same time. Three configurations of the reactor were compared: empty, filled with inert glass beads and filled with faujasite pellets. First, ozone transfer coefficient (k(L)a) and decomposition rate constant (k(C)) were determined for each configuration. In presence of solid, k(L)a was 2.0 to 2.6 times higher and k(C) was 5.0 to 6.4 times higher compared to the empty reactor. Then, the various configurations were evaluated in terms of NB removal and chemical oxygen demand (COD) decrease. The faujasite reactor showed higher removal of NB and decrease of COD compared to other configurations under the same conditions suggesting that the faujasite increases the oxidation rate of NB. Oxidation of NB in presence of faujasite also proved to be limited by the transfer of ozone from the gas to the liquid phase.

Evaluation Of Oxide And Silicide Mixed Fuels Of The RSG-GAS Core

International Nuclear Information System (INIS)

Tukiran; Sembiring, Tagor Malem; Suparlina, Lily

2000-01-01

Fuel exchange of the RSG-GAS reactor core from uranium oxide to uranium silicide in the same loading, density, and enrichment, that is 250 gr, 2.98 gr/cm 3 , and 19.75%, respectively, will be performed in-step wise. In every cycle of exchange with 5/1 mode, it is needed to evaluate the parameter of reactor core operation. The parameters of the reactor operation observed are criticality mass of fuels, reactivity balance, and fuel reactivity that give effect to the reactor operation. The evaluation was done at beginning of cycle of the first and second transition core with compared between experiment and calculation results. The experiments were performed at transition core I and II, BOC, and low power. At transition core I, there are 2 silicide fuels (RI-224 and R1-225) in the core and then, added five silicide fuels (R1-226, R1-252, R1-263, and R1-264) to the core, so that there are seven silicide fuels in the transition core II. The evaluation was done based on the experiment of criticality, control rod calibration, fuel reactivity of the RSG-GAS transition core. For inserting 2 silicide fuels in the transition core I dan 7 fuels in the transition core II, the operation of RSG-GAS core fulfilled the safety margin and the parameter of reactor operation change is not occur drastically in experiment and calculation results. So that, the reactor was operated during 36 days at 15 MW, 540 MWD at the first transition core. The general result showed that the parameter of reactor operation change is small so that the fuel exchange from uranium oxide to uranium silicide in the next step can be done

Method for the combustion of a gas, in fixed bed, with an oxidized solid and associated installation

OpenAIRE

Abanades García, Juan Carlos; Fernández García, José Ramón

2014-01-01

[EN] The present invention pertains to the field of the generation of energy from combustible gases, incorporating the capture of carbon dioxide for use or permanent storage and, specifically relates to cyclical methods of gas combustion with oxidized solids (chemical looping processes), in fixed bed, for solving the problem of controlling temperature in the combustion of gaseous fuels in fixed beds of metal oxides operating at high pressures, and also the associated installation.

Gas-Phase Thermolysis of a Thioketen-S-Oxide

DEFF Research Database (Denmark)

Carlsen, Lars; Egsgaard, Helge; Schaumann, Ernst

1980-01-01

The unimolecular gas-phase thermolytic decomposition of 1,1,3,3-tetramethyl-2-thiocarbonylcyclohexane S-oxide (3) has been studied as a function of temperature by a flash vacuum thermolysis (f.v.t.) technique. The products detected are the carbenes (4) and (5), the ketone (6), the keten (7......), the thioketone (8), and the thioketen (9). The product ratio is highly dependent on the thermolysis temperature. The thermolysis of (3) is mechanistically rationalized by assuming the existence of only two concurrent primary processes, which are (a) extrusion of atomic oxygen, leading to the thioketen (9...... and CSO leading to the carbenes (5) and (4), respectively, are observed. Owing to an apparently very short half-life of the oxathiiran (10), only the decomposition products of the three-membered ring compound have been detected. These are the thioketone (8), formed by rearrangement of (10) into the α...

Electron microscopic studies of natural gas oxidation catalyst – Effects of thermally accelerated aging on catalyst microstructure

DEFF Research Database (Denmark)

Honkanen, Mari; Hansen, Thomas Willum; Jiang, Hua

2017-01-01

Structural changes of PtPd nanoparticles in a natural gas oxidation catalyst were studied at elevated temperatures in air and low-oxygen conditions and in situ using environmental transmission electron microscopy (ETEM). The fresh catalyst shows

Development of a novel gas sensor based on oxide thick films

International Nuclear Information System (INIS)

Arshak, K.; Gaidan, I.

2005-01-01

Zinc and iron oxide thick film gas sensors were fabricated using screen-printing technology on glass substrates that had silver interdigitated electrodes. The sensor was used to detect methanol, ethanol and propanol with a concentration range of 0-8000 ppm. Using the formula to calculate a change in resistance, ΔR = R gas - R air, resistance was seen to increase linearly alongside increasing concentrations of the gas vapours. The sensor showed the highest sensitivity to propanol followed by ethanol and methanol when the operating temperature was 25 deg. C. The sensitivities (slope of graphs) of methanol, ethanol and propanol changed from 0.07, 0.5, and 3.54 to 0.075, 0.115, and 0.5 Ω/ppm when the operating temperature was increased from 25 to 50 deg. C. The response/recovery times of the sensor for 4000 ppm at room temperature were, 10/10, 15/20 and 40/70 s for methanol, ethanol and propanol, respectively. X-ray diffraction (XRD) was used to examine the final composition of the film, while scanning electron microscopy (SEM) was used to examine the final composition of grain size. The final composition has two phases: ZnO and ZnFe 2 O 4

Effect of surface composition of yttrium-stabilized zirconia on partial oxidation of methane to synthesis gas.

NARCIS (Netherlands)

Zhu, J.J.; van Ommen, J.G.; Knoester, A.; Lefferts, Leonardus

2005-01-01

Catalytic partial oxidation of methane to synthesis gas (CPOM) over yttrium-stabilized zirconia (YSZ) was studied within a wide temperature window (500¿1100 °C). The catalysts were characterized by X-ray fluorescence (XRF) and low-energy ion scattering (LEIS). The influence of calcination

Preparation and characterization of indium tin oxide thin films for their application as gas sensors

International Nuclear Information System (INIS)

Vaishnav, V.S.; Patel, P.D.; Patel, N.G.

2005-01-01

The structural and electrical properties of indium tin oxide (In 2 O 3 /SnO 2 ) thin films grown using direct evaporation technique on various substrates at different temperatures were studied. The effect of annealing, of films with different weight percent concentration of SnO 2 in In 2 O 3 and of different thickness on the structural and electrical properties were studied and optimized for use as gas sensor. The stability of the films against time and temperature variations was studied. The effect of the catalytic layers on the sensor microstructure and its performance towards the gas sensing application was observed

Mathematical modeling of synthesis gas fueled electrochemistry and transport including H2/CO co-oxidation and surface diffusion in solid oxide fuel cell

Science.gov (United States)

Bao, Cheng; Jiang, Zeyi; Zhang, Xinxin

2015-10-01

Fuel flexibility is a significant advantage of solid oxide fuel cell (SOFC). A comprehensive macroscopic framework is proposed for synthesis gas (syngas) fueled electrochemistry and transport in SOFC anode with two main novelties, i.e. analytical H2/CO electrochemical co-oxidation, and correction of gas species concentration at triple phase boundary considering competitive absorption and surface diffusion. Staring from analytical approximation of the decoupled charge and mass transfer, we present analytical solutions of two defined variables, i.e. hydrogen current fraction and enhancement factor. Giving explicit answer (rather than case-by-case numerical calculation) on how many percent of the current output contributed by H2 or CO and on how great the water gas shift reaction plays role on, this approach establishes at the first time an adaptive superposition mechanism of H2-fuel and CO-fuel electrochemistry for syngas fuel. Based on the diffusion equivalent circuit model, assuming series-connected resistances of surface diffusion and bulk diffusion, the model predicts well at high fuel utilization by keeping fixed porosity/tortuosity ratio. The model has been validated by experimental polarization behaviors in a wide range of operation on a button cell for H2-H2O-CO-CO2-N2 fuel systems. The framework could be helpful to narrow the gap between macro-scale and meso-scale SOFC modeling.

75 FR 11171 - Transparency Provisions of Section 23 of the Natural Gas Act; Supplemental Notice to Form No. 552...

Science.gov (United States)

2010-03-10

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. RM07-10-002] Transparency Provisions of Section 23 of the Natural Gas Act; Supplemental Notice to Form No. 552 Technical Conference March 1, 2010. As announced in the Notice of Technical Conference issued on February 22, 2010, a...

Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

DEFF Research Database (Denmark)

Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

1995-01-01

Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost...

Development of a selective oxidation CO removal reactor for methanol reformate gas

Energy Technology Data Exchange (ETDEWEB)

Okada, Shunji; Takatani, Yoshiaki; Terada, Seijo; Ohtani, Shinichi [Kawasaki Heavy Industry, Ltd., Hyogo-ken (Japan)] [and others

1996-12-31

This report forms part of a joint study on a PEFC propulsion system for surface ships, summarized in a presentation to this Seminar, entitled {open_quotes}Study on a Polymer Electrolyte Fuel Cell (PEFC) Propulsion System for Surface Ships{close_quotes}, and which envisages application to a 1,500 DWT cargo vessel. The aspect treated here concerns laboratory-scale tests aimed at reducing by selective oxidation to a level below 10 ppm the carbon monoxide (CO) contained to a concentration of around 1% in reformate gas.

Transient redistribution of intragranular fission gas in irradiated mixed oxide

International Nuclear Information System (INIS)

Hinman, C.A.; Randklev, E.H.

1981-01-01

Safety analyses for an LMFBR require a knowledge of the fuel and fission gas behavior under transient conditions. Analyses of microstructural data derived from transiently heated, irradiated, mixed oxide fuel specimens have allowed the calculation of the degree of nonequilibrium of intragranular bubbles formed during the transient. It is hypothesized that the observed over-pressurization of the intragranular bubbles mechanically loads the fuel within the grain, leading to a stress gradient derived force upon near-grain-surface bubbles, driving them preferentially to the grain boundaries. Using existing models for forced diffusion it can be estimated that the stress derived forces on bubbles are within the same magnitude, and possibly greater, than the forces derived from the thermal gradient

The fabrication of high sensitivity gold nanorod H2S gas sensors utilizing the highly uniform anodic aluminum oxide template

Directory of Open Access Journals (Sweden)

Chien-Yu Li

2016-12-01

Full Text Available Gold nanorod were fabricated using anodic alumina oxide template for H2S gas detection. The nanorod gas sensor exhibits high surface density and contact area, which can increase detection sensitivity. The anodic alumina oxide template contains an array of pores, with a width of 70 nm and a length of 27μm. Au nanorod were obtained through electro-deposition under a pulse bias of −1 V. The resistance of the Au nanorod was recorded upon exposure to various concentrations of H2S. The resistance could be attributed to the high electron affinity between sulfide and Au nanorod. Au–sulfide bonds provide strong bonding, which could alter the conductivity of the sensor. The gas sensor exhibits high sensitivity and short response time for H2S detection at room temperature.

Characterization and gas-sensing behavior of an iron oxide thin film prepared by atomic layer deposition

International Nuclear Information System (INIS)

Aronniemi, Mikko; Saino, J.; Lahtinen, J.

2008-01-01

In this work we investigate an iron oxide thin film grown with atomic layer deposition for a gas sensor application. The objective is to characterize the structural, chemical, and electrical properties of the film, and to demonstrate its gas-sensitivity. The obtained scanning electron microscopy and atomic force microscopy results indicate that the film has a granular structure and that it has grown mainly on the glass substrate leaving the platinum electrodes uncovered. X-ray diffraction results show that iron oxide is in the α-Fe 2 O 3 (hematite) phase. X-ray photoelectron spectra recorded at elevated temperature imply that the surface iron is mainly in the Fe 3+ state and that oxygen has two chemical states: one corresponding to the lattice oxygen and the other to adsorbed oxygen species. Electric conductivity has an activation energy of 0.3-0.5 eV and almost Ohmic current-voltage dependency. When exposed to O 2 and CO, a typical n-type response is observed

High pressure operation of tubular solid oxide fuel cells and their intergration with gas turbines

Energy Technology Data Exchange (ETDEWEB)

Haynes, C.; Wepfer, W.J. [Georgia Institute of Technology, Atlanta, GA (United States)

1996-12-31

Fossil fuels continue to be used at a rate greater than that of their natural formation, and the current byproducts from their use are believed to have a detrimental effect on the environment (e.g. global warming). There is thus a significant impetus to have cleaner, more efficient fuel consumption alternatives. Recent progress has led to renewed vigor in the development of fuel cell technology, which has been shown to be capable of producing high efficiencies with relatively benign exhaust products. The tubular solid oxide fuel cell developed by Westinghouse Electric Corporation has shown significant promise. Modeling efforts have been and are underway to optimize and better understand this fuel cell technology. Thus far, the bulk of modeling efforts has been for operation at atmospheric pressure. There is now interest in developing high-efficiency integrated gas turbine/solid oxide fuel cell systems. Such operation of fuel cells would obviously occur at higher pressures. The fuel cells have been successfully modeled under high pressure operation and further investigated as integrated components of an open loop gas turbine cycle.

Room temperature H2S gas sensing property of indium oxide thin films obtained by pulsed D.C. magnetron sputtering

International Nuclear Information System (INIS)

Nisha, R.; Madhusoodanan, K.N.; Karthikeyan, Sreejith; Hill, Arthur E.; Pilkington, Richard D.

2013-01-01

Indium oxide thin films were prepared by pulsed dc magnetron sputtering technique with no substrate heating. X-ray diffraction was used to investigate the structural properties and AFM was used to study the surface morphology gas sensing performance were conducted using a static gas sensing system. Room temperature gas sensing performance was conducted in range of 17 to 286 ppm. The sensitivity, response and recovery time of the sensor was also determined. (author)

75 FR 9202 - Transparency Provisions of Section 23 of the Natural Gas Act; Notice of Form No. 552 Technical...

Science.gov (United States)

2010-03-01

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. RM07-10-002] Transparency... will be open to the public; there is no registration to attend.\\2\\ \\1\\ Transparency Provisions of...); Transparency Provisions of Section 23 of the Natural Gas Act, Order No. 704-A, FERC Stats. & Regs. ] 31,275...

The Oxidation of Dibenzothiophene using Oxidovanadium(IV ...

African Journals Online (AJOL)

NICOLAAS

progress of oxidation was followed with a gas chromatograph fitted with a flame ionization detector. ... the extraction of the oxidation products.11–17. Several oxidants ..... house-gas footprint of natural gas from shale formations, Clim. Change ...

Analyzer for measurement of nitrogen oxide concentration by ozone content reduction in gas using solid state chemiluminescent sensor

Science.gov (United States)

Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.

2014-05-01

Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01

Deregulation of natural gas in Georgia

International Nuclear Information System (INIS)

Wise, S.

2002-01-01

The Natural Gas Competition and Deregulation Act of 1997 in Georgia is discussed. New legislation passed the Natural Gas Consumer Relief Act in 2002 legislative session to provide additional protection and increase competition. This Act and its impacts are discussed in detail. Additional commission responsibilities are summarized. (R.P.)

Investigation of Pristine Graphite Oxide as Room-Temperature Chemiresistive Ammonia Gas Sensing Material

Directory of Open Access Journals (Sweden)

Alexander G. Bannov

2017-02-01

Full Text Available Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10–1000 ppm and under different relative humidity levels (3%–65%. It was concluded that the graphite oxide–based sensor possessed a good response to NH3 in dry synthetic air (ΔR/R0 ranged from 2.5% to 7.4% for concentrations of 100–500 ppm and 3% relative humidity with negligible cross-sensitivity towards H2 and CH4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level.

Gas atomized precursor alloy powder for oxide dispersion strengthened ferritic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Rieken, Joel [Iowa State Univ., Ames, IA (United States)

2011-12-13

Gas atomization reaction synthesis (GARS) was employed as a simplified method for producing precursor powders for oxide dispersion strengthened (ODS) ferritic stainless steels (e.g., Fe-Cr-Y-(Ti,Hf)-O), departing from the conventional mechanical alloying (MA) process. During GARS processing a reactive atomization gas (i.e., Ar-O₂) was used to oxidize the powder surfaces during primary break-up and rapid solidification of the molten alloy. This resulted in envelopment of the powders by an ultra-thin (t < 150 nm) metastable Cr-enriched oxide layer that was used as a vehicle for solid-state transport of O into the consolidated microstructure. In an attempt to better understand the kinetics of this GARS reaction, theoretical cooling curves for the atomized droplets were calculated and used to establish an oxidation model for this process. Subsequent elevated temperature heat treatments, which were derived from Rhines pack measurements using an internal oxidation model, were used to promote thermodynamically driven O exchange reactions between trapped films of the initial Cr-enriched surface oxide and internal Y-enriched intermetallic precipitates. This novel microstructural evolution process resulted in the successful formation of nano-metric Y-enriched dispersoids, as confirmed using high energy X-ray diffraction and transmission electron microscopy (TEM), equivalent to conventional ODS alloys from MA powders. The thermal stability of these Y-enriched dispersoids was evaluated using high temperature (1200°C) annealing treatments ranging from 2.5 to 1,000 hrs of exposure. In a further departure from current ODS practice, replacing Ti with additions of Hf appeared to improve the Y-enriched dispersoid thermal stability by means of crystal structure modification. Additionally, the spatial distribution of the dispersoids was found to depend strongly on the original rapidly solidified microstructure. To exploit this, ODS microstructures were engineered from

A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas.

Science.gov (United States)

Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J; Lang, Walter

2017-10-07

Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system.

Validation of an analytical method for nitrous oxide (N2O) laughing gas by headspace gas chromatography coupled to mass spectrometry (HS-GC-MS): forensic application to a lethal intoxication.

Science.gov (United States)

Giuliani, N; Beyer, J; Augsburger, M; Varlet, V

2015-03-01

Drug abuse is a widespread problem affecting both teenagers and adults. Nitrous oxide is becoming increasingly popular as an inhalation drug, causing harmful neurological and hematological effects. Some gas chromatography-mass spectrometry (GC-MS) methods for nitrous oxide measurement have been previously described. The main drawbacks of these methods include a lack of sensitivity for forensic applications; including an inability to quantitatively determine the concentration of gas present. The following study provides a validated method using HS-GC-MS which incorporates hydrogen sulfide as a suitable internal standard allowing the quantification of nitrous oxide. Upon analysis, sample and internal standard have similar retention times and are eluted quickly from the molecular sieve 5Å PLOT capillary column and the Porabond Q column therefore providing rapid data collection whilst preserving well defined peaks. After validation, the method has been applied to a real case of N2O intoxication indicating concentrations in a mono-intoxication. Copyright © 2015 Elsevier B.V. All rights reserved.

Integration of A Solid Oxide Fuel Cell into A 10 MW Gas Turbine Power Plant

Directory of Open Access Journals (Sweden)

Denver F. Cheddie

2010-04-01

Full Text Available Power generation using gas turbine power plants operating on the Brayton cycle suffers from low efficiencies. In this work, a solid oxide fuel cell (SOFC is proposed for integration into a 10 MW gas turbine power plant, operating at 30% efficiency. The SOFC system utilizes four heat exchangers for heat recovery from both the turbine outlet and the fuel cell outlet to ensure a sufficiently high SOFC temperature. The power output of the hybrid plant is 37 MW at 66.2% efficiency. A thermo-economic model predicts a payback period of less than four years, based on future projected SOFC cost estimates.

Yellowing of coated papers under the action of heat, daylight radiation, and nitrogen oxide gas

International Nuclear Information System (INIS)

Mailly, V.; Le Nest, J.F.; Tosio, J.M.S.; Silvy, J.

1997-01-01

In the area of coated papers, a high degree of whiteness is often required to carry a quality image. Coated papers however are sensitive to the environment where they are stored and have tendency to yellow. The aim of this work was to study the influence of(i) daylight radiation and (ii) nitrogen oxide gas (NO2 ) on the yellowing of coated papers. In a previous study (l), we had established the presence of NO2 in the environment of some coating machines because of the transformation of ammonium hydroxide (NH4 OH, a component of some coating colors) into nitrogen oxide through the burners of hot air supplier-systems

Managing of gas sensing characteristic of a reduced graphene oxide based gas sensor by the change in synthesis condition: A new approach for electronic nose design

Energy Technology Data Exchange (ETDEWEB)

Alizadeh, Taher, E-mail: talizadeh@ut.ac.ir [Department of Analytical Chemistry, Faculty of Chemistry, University College of Science, University of Tehran, P.O. Box 14155-6455, Tehran (Iran, Islamic Republic of); Hamedsoltani, Leyla [Department of Applied Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

2016-11-01

Natural graphite was oxidized and exfoliated via two different methods, leading to two types of graphene oxide (GO) materials. The obtained materials were reduced by three different reducing agents including: hydrazine hydrate, ascorbic acid and sodium borohydride, giving thus six kinds of reduced graphene oxide (RGO) materials. The obtained materials were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The RGOs were then used to fabricate different gas sensors and their electrical resistances were recorded upon exposing to various volatile organic compounds vapors (VOCs). Gas sensing selectivity of each RGO was significantly affected by the synthesis condition. The RGO-based sensor array was fabricated and its capability for discrimination of seven kinds of VOCs was evaluated, utilizing principal component analysis and cluster analysis methods. Loading plot indicated that the presence of five RGO-based sensors could effectively discriminate the aimed vapors. The electronic nose, containing five kinds of RGOs, was used for the classification of seven kinds of VOCs at their different concentrations. - Highlights: • Two oxidation procedures and three reducing agents were utilized to produce six kinds of RGOs. • The synthesized different RGOs exhibited significantly different sensing behaviors. • Seven kinds of organic vapors were chosen for the evaluation of discrimination power of EN. • Using PCA, it was found that seven of six RFGOs were appropriate number to use in final EN. • The developed EN was capable of properly discrimination of tested vapors.

Alternative anode materials for solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Goodenough, John B.; Huang, Yun-Hui [Texas Materials Institute, ETC 9.102, 1 University Station, C2200, The University of Texas at Austin, Austin, TX 78712 (United States)

2007-11-08

The electrolyte of a solid oxide fuel cell (SOFC) is an O{sup 2-}-ion conductor. The anode must oxidize the fuel with O{sup 2-} ions received from the electrolyte and it must deliver electrons of the fuel chemisorption reaction to a current collector. Cells operating on H{sub 2} and CO generally use a porous Ni/electrolyte cermet that supports a thin, dense electrolyte. Ni acts as both the electronic conductor and the catalyst for splitting the H{sub 2} bond; the oxidation of H{sub 2} to H{sub 2}O occurs at the Ni/electrolyte/H{sub 2} triple-phase boundary (TPB). The CO is oxidized at the oxide component of the cermet, which may be the electrolyte, yttria-stabilized zirconia, or a mixed oxide-ion/electron conductor (MIEC). The MIEC is commonly a Gd-doped ceria. The design and fabrication of these anodes are evaluated. Use of natural gas as the fuel requires another strategy, and MIECs are being explored for this application. The several constraints on these MIECs are outlined, and preliminary results of this on-going investigation are reviewed. (author)

Decision NSUARB-NG-98: in the matter of the Gas Distribution Act and in the matter of franchise applications for the distribution of natural gas in the province of Nova Scotia

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-16

A decision was rendered following a public hearing conducted by the Nova Scotia Utility and Review Board (the Board) over 49 hearing days between April 12, 1999 and July 29, 1999, in the matter of applications for franchises to construct and operate natural gas delivery systems in the province of Nova Scotia under the authority of various acts. Part One of the report consists of the Board's findings on the province-wide franchise applications. Each application was evaluated in the context of the statutory, regulatory and policy criteria established by the Act and GIC Regulations. The Board drew from these criteria upon which its decision was based. A brief summary of the evidence provided by each applicant in respect of each key factor is presented, followed by the Board's findings in respect of that factor. Part two deals with the applications by the municipalities and co-operatives. A brief summary of each proposal is set out along with the Board's findings. Part three consists of comments by the Board in respect of other issues, including the regulatory environment, single end user franchises and municipal fees. Part four contains a summary of the Board's findings and conclusions. An addendum contains six schedules. Pursuant to Section 8 of the Gas Distribution Act, the Board granted a full regulation class franchise for a period of 25 years to Sempra Atlantic Gas Inc., subject to the approval of the Governor in Council and subject to the conditions set forth in Schedule 'A' attached; all other applications denied.

Operation of real landfill gas fueled solid oxide fuel cell (SOFC) using internal dry reforming

DEFF Research Database (Denmark)

Langnickel, Hendrik; Hagen, Anke

2017-01-01

Biomass is one renewable energy source, which is independent from solar radiation and wind effect. Solid oxide fuel cells (SOFC’s) are able to convert landfill gas derived from landfill directly into electricity and heat with a high efficiency. In the present work a planar 16cm2 SOFC cell...... was necessary to prevent poisoning and thereby to decrease the degradation rate....

Methane Emissions from Landfill: Isotopic Evidence for Low Percentage of Oxidation from Gas Wells, Active and Closed Cells

Science.gov (United States)

Lowry, David; Fisher, Rebecca; Zazzeri, Giulia; al-Shalaan, Aalia; France, James; Lanoisellé, Mathias; Nisbet, Euan

2017-04-01

Large landfill sites remain a significant source of methane emissions in developed and developing countries, with a global estimated flux of 29 Tg / yr in the EDGAR 2008 database. This is significantly lower than 20 years ago due to the introduction of gas extraction systems, but active cells still emit significant amounts of methane before the gas is ready for extraction. Historically the methane was either passively oxidized through topsoil layers or flared. Oxidation is still the primary method of methane removal in many countries, and covered, remediated cells across the world continue to emit small quantities of methane. The isotopic signatures of methane from landfill gas wells, and that emitted from active and closed cells have been characterized for more than 20 UK landfills since 2011, with more recent work in Kuwait and Hong Kong. Since 2013 the emission plumes have been identified by a mobile measurement system (Zazzeri et al., 2015). Emissions in all 3 countries have a characteristic δ13C signature of -58 ± 3 ‰ dominated by emissions from the active cells, despite the hot, dry conditions of Kuwait and the hot, humid conditions of Hong Kong. Gas well samples define a similar range. Surface emissions from closed cells and closed landfills are mostly in the range -56 to -52 ‰Ṫhese are much more depleted values than those observed in the 1990s (up to -35 ) when soil oxidation was the dominant mechanism of methane removal. Calculations using isotopic signatures of the amount of methane oxidised in these closed areas before emission to atmosphere range from 5 to 15%, but average less than 10%, and are too small to calculate from the high-emitting active cells. Compared to other major methane sources, landfills have the most consistent isotopic signature globally, and are distinct from the more 13C-enriched natural gas, combustion and biomass burning sources. Zazzeri, G. et al. (2015) Plume mapping and isotopic characterization of anthropogenic methane

Scalable fractionation of iron oxide nanoparticles using a CO2 gas-expanded liquid system

International Nuclear Information System (INIS)

Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B.

2015-01-01

Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO 2 gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

Characterization of Reduced Graphene Oxide (rGO-Loaded SnO2 Nanocomposite and Applications in C2H2 Gas Detection

Directory of Open Access Journals (Sweden)

Lingfeng Jin

2016-12-01

Full Text Available Acetylene (C2H2 gas sensors were developed by synthesizing a reduced graphene oxide (rGO-loaded SnO2 hybrid nanocomposite via a facile two-step hydrothermal method. Morphological characterizations showed the formation of well-dispersed SnO2 nanoparticles loaded on the rGO sheets with excellent transparency and obvious fold boundary. Structural analysis revealed good agreement with the standard crystalline phases of SnO2 and rGO. Gas sensing characteristics of the synthesized materials were carried out in a temperature range of 100–300 °C with various concentrations of C2H2 gas. At 180 °C, the SnO2–rGO hybrid showed preferable detection of C2H2 with high sensor response (12.4 toward 50 ppm, fast response-recovery time (54 s and 23 s, limit of detection (LOD of 1.3 ppm and good linearity, with good selectivity and long-term stability. Furthermore, the possible gas sensing mechanism of the SnO2–rGO nanocomposites for C2H2 gas were summarized and discussed in detail. Our work indicates that the addition of rGO would be effective in enhancing the sensing properties of metal oxide-based gas sensors for C2H2 and may make a contribution to the development of an excellent ppm-level gas sensor for on-line monitoring of dissolved C2H2 gas in transformer oil.

Development of metal oxide gas sensors for very low concentration (ppb) of BTEX vapors

Science.gov (United States)

Favard, A.; Aguir, K.; Contaret, T.; Caris, L.; Bendahan, M.

2017-12-01

The control and analysis of air quality have become a major preoccupation of the last twenty years. In 2008, the European Union has introduced a Directive (2008/50/EC) to impose measurement obligations and thresholds to not exceed for some pollutants, including BTEX gases, in view of their adverse effects on the health. In this paper, we show the ability to detect very low concentrations of BTEX using a gas microsensor based on metal oxide thin-film. A test bench able to generate very low vapors concentrations has been achieved and fully automated. Thin metal oxides layers have been realized by reactive magnetron sputtering. The sensitive layers are functionalized with gold nanoparticles by thermal evaporation technique. Our sensors have been tested on a wide range of concentrations of BTEX (5 - 500 ppb) and have been able to detect concentrations of a few ppb for operating temperatures below 593 K. These results are very promising for detection of very low BTEX concentration for indoor as well as outdoor application. We showed that the addition of gold nanoparticles on the sensitive layers decreases the sensors operating temperature and increases the response to BTEX gas. The best results are obtained with a sensitive layer based on ZnO.

Elimination of methane in exhaust gas from biogas upgrading process by immobilized methane-oxidizing bacteria.

Science.gov (United States)

Wu, Ya-Min; Yang, Jing; Fan, Xiao-Lei; Fu, Shan-Fei; Sun, Meng-Ting; Guo, Rong-Bo

2017-05-01

Biogas upgrading is essential for the comprehensive utilization of biogas as substitute of natural gas. However, the methane in the biogas can be fully recovered during the upgrading process of biogas, and the exhaust gas produced during biogas upgrading may contain a very low concentration of methane. If the exhaust gas with low concentration methane releases to atmosphere, it will be harmful to environment. In addition, the utilization of large amounts of digestate produced from biogas plant is another important issue for the development of biogas industry. In this study, solid digestate was used to produce active carbon, which was subsequently used as immobilized material for methane-oxidizing bacteria (MOB) in biofilter. Biofilter with MOB immobilized on active carbon was used to eliminate the methane in exhaust gas from biogas upgrading process. Results showed porous active carbon was successfully made from solid digestate. The final methane elimination capacity of immobilized MOB reached about 13molh -1 m -3 , which was more 4 times higher than that of MOB without immobilization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study of a hybrid system using solid oxide fuel cells (SOFC) and gas turbine; Estudo de um sistema hibrido empregando celula de combustivel de oxido solido (SOFC) e turbina a gas

Energy Technology Data Exchange (ETDEWEB)

Souza, Antonio Carlos Caetano de; Gallo, Giulliano Batelochi; Silveira, Jose Luz [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia. Dept. de Energia], e-mail: caetano@feg.unesp.br

2004-07-01

In this paper a hybrid solid oxide fuel cell (SOFC) system, applying a combined cycle using gas turbine for rational decentralized energy production is analyzed. The relative concepts about the fuel cell are presented, followed by some chemical and technical information such as the change of Gibbs free energy in isothermal fuel oxidation directly into electricity. This represents a very high fraction of the lower heating value (LHV) of a hydrocarbon fuel. In the next step a methodology for the study of SOFC and gas turbine system is developed, considering the electricity and steam production for a hospital. This methodology is applied to energetic analysis. Natural gas is considered as a fuel. A Sankey Diagram shows that the hybrid SOFC system is a good opportunity to strengthen the decentralized energy production in Brazil. It is necessary to consider that the cogeneration in this version also is a good technical alternative, demanding special methods of design, equipment selection and contractual deals associated to electricity and fuel supply. (author)

Accidental behaviour of nuclear fuel in a warehousing site under air: investigation of the nuclear ceramic oxidation and of fission gas release

International Nuclear Information System (INIS)

Desgranges, L.

2006-12-01

After a brief presentation of the context of his works, i.e. the nuclear fuel, its behaviour in a nuclear reactor, and studies performed in high activity laboratory, the author more precisely presents its research topic: the behaviour of defective nuclear fuel in air. Then, he describes the researches performed in three main directions: firstly, the characterization and understanding of fission gas localisation (experimental localisation, understanding of the bubble forming mechanisms), secondly, the determination of mechanisms related to oxidation (atomic mechanisms related to UO 2 oxidation, oxidation of fragments of irradiated fuel, the CROCODILE installation). He finally presents his scientific project which notably deals with fission gas release (from UO 2 to U 3 O 7 , and from U 3 O 7 to U 3 O 8 ), and with further high activity laboratory experiments

75 FR 13523 - Transparency Provisions of Section 23 of the Natural Gas Act; Notice of the Agenda for Form No...

Science.gov (United States)

2010-03-22

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. RM07-10-002] Transparency Provisions of Section 23 of the Natural Gas Act; Notice of the Agenda for Form No. 552 Technical Conference March 15, 2010. In a ``Notice of Technical Conference'' issued on February 22, 2010 in the above...

Natural gas and the environment

International Nuclear Information System (INIS)

DeCarufel, A.

1991-01-01

The role of various atmospheric pollutants in environmental changes and the global water cycle, carbon cycle, and energy balance is explained. The role of sulfur dioxide and nitrogen oxides in acid deposition is also outlined. The pollutants that contribute to environmental problems include nitrogen oxides and volatile organic compounds, carbon dioxide, and other greenhouse gases. The potential for natural gas utilization to mitigate some of these pollution problems is explored. Natural gas combustion emits less carbon dioxide and nitrogen oxides than combustion of other fossil fuel, and also does not produce sulfur dioxide, particulates, or volatile organics. Other pollution controlling opportunities offered by natural gas include the use of low-polluting burners, natural gas vehicles, and cogeneration systems. 18 figs., 4 tabs

Amendment of the Energy Economy Act. Novellierung des Energiewirtschaftsgesetzes

Energy Technology Data Exchange (ETDEWEB)

1990-12-20

The Federal Association of German Industry deliberates on the reform of the Energy Economy Act, arriving at the following intermediate result that is to be discussed by the member associations. The following might be essential points for the attitude of the industry regarding the reform of the energy economy act: deregulation, qualitative modernization, concentration on electric power and gas, differentiated regulations for power and gas, limitation of municipal influence (outside the scope of the energy economy act: reform of the municipal right of way), secure power and gas supply at internationally competitive prices. This is followed by considerations regarding the individual provisions of the energy economy act and their discussion. (orig./HSCH).

Macular hole surgery with short-acting gas and short-duration face-down positioning

Directory of Open Access Journals (Sweden)

Xirou T

2012-07-01

Full Text Available Tina Xirou,1 Panagiotis G Theodossiadis,2 Michael Apostolopoulos,3 A Stamatina Kabanarou,1 Elias Feretis,1 Ioannis D Ladas,3 Chrysanthi Koutsandrea31Vitreoretinal Unit, Red Cross Hospital, 2B Department of Ophthalmology, University of Athens, Greece; 3A Department of Ophthalmology, University of Athens, GreecePurpose: To report on the outcomes of vitrectomy and sulfur hexafluoride (SF6 gas tamponade for idiopathic macular holes with 2 days of face-down positioning.Patients and methods: This was a prospective, nonrandomized, observational sequential case-series study on 23 consecutive patients receiving macular hole surgery using 20% SF6 and advised to stay in a face-down position for 2 days postoperatively (SF6 group. These patients were compared to 23 consecutive patients who had previously undergone macular hole surgery, had received 14% C3F8, and were advised to maintain a face-down position for 2 days (C3F8 group. Patients in both groups underwent vitrectomy, internal limiting membrane peeling, and fluid gas exchange using either SF6 or C3F8. Preoperative and postoperative data included best corrected visual acuity recorded in LogMAR units, slit-lamp biomicroscopy, and optical coherence tomography.Results: At a 6-month follow-up, macular hole closure was noted in 23/23 eyes (100% and in 22/23 eyes (96% in the SF6 and C3F8 groups, respectively. The improvement in visual acuity (measured through Snellen acuity lines both preoperatively until 6 months postoperatively was 4.08 ± 2.31 (95% confidence interval [CI]: 3.08–5.08 for the SF6 group and 2.87 ± 2.30 (95% CI: 1.87–3.86 for the C3F8 group; this difference was not statistically significant (P = 0.06.Conclusion: Vitrectomy with internal limiting membrane peeling and a short-acting gas tamponade using SF6 with posture limitation for 2 days may give a high success rate in macular hole surgery.Keywords: idiopathic macular holes, SF6 gas tamponade, C3F8 gas tamponade

Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing in Aerospace Applications

Science.gov (United States)

VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.; Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.

2009-01-01

A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine an activation energy for the catalyst-assisted systems.

Improved enrichment culture technique for methane-oxidizing bacteria from marine ecosystems: the effect of adhesion material and gas composition.

Science.gov (United States)

Vekeman, Bram; Dumolin, Charles; De Vos, Paul; Heylen, Kim

2017-02-01

Cultivation of microbial representatives of specific functional guilds from environmental samples depends largely on the suitability of the applied growth conditions. Especially the cultivation of marine methanotrophs has received little attention, resulting in only a limited number of ex situ cultures available. In this study we investigated the effect of adhesion material and headspace composition on the methane oxidation activity in methanotrophic enrichments obtained from marine sediment. Addition of sterilized natural sediment or alternatively the addition of acid-washed silicon dioxide significantly increased methane oxidation. This positive effect was attributed to bacterial adhesion on the particles via extracellular compounds, with a minimum amount of particles required for effect. As a result, the particles were immobilized, thus creating a stratified environment in which a limited diffusive gas gradients could build up and various microniches were formed. Such diffusive gas gradient might necessitate high headspace concentrations of CH 4 and CO 2 for sufficient concentrations to reach the methane-oxidizing bacteria in the enrichment culture technique. Therefore, high concentrations of methane and carbon dioxide, in addition to the addition of adhesion material, were tested and indeed further stimulated methane oxidation. Use of adhesion material in combination with high concentrations of methane and carbon dioxide might thus facilitate the cultivation and subsequent enrichment of environmentally important members of this functional guild. The exact mechanism of the observed positive effects on methane oxidation and the differential effect on methanotrophic diversity still needs to be explored.

Characterization and Gas Sensing Properties of Copper-doped Tin Oxide Thin Films Deposited by Ultrasonic Spray Pyrolysis

Directory of Open Access Journals (Sweden)

Zhaoxia ZHAI

2016-05-01

Full Text Available Tin oxide-based thin films are deposited by ultrasonic spray pyrolysis technology, in which Cu addition is introduced to enhance the gas sensing performance by H2S detection. The thin films are porous and comprise nano-sized crystallites. One of the Cu-containing thin film sensors demonstrates a fast and significant response to H2S gas. The values of power law exponent n are calculated to discuss the sensitivity of the sensors, which is significantly promoted by Cu additive. The sensitivity of Cu-doped SnO2 gas sensors is determined by two mechanisms. One is the normal gas sensing mechanism of SnO2 grains, and the other is the promoted mechanism caused by the transformation between CuO and CuS in the H2S detection. DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12917

Soot oxidation over NOx storage catalysts. Activity and deactivation

International Nuclear Information System (INIS)

Krishna, K.; Makkee, M.

2006-01-01

Soot oxidation activity and deactivation of NO x storage and reduction (NSR) catalysts containing Pt, K, and Ba supported on Al 2 O 3 , are studied under a variety of reaction conditions. K-containing catalysts decrease soot oxidation temperature with O 2 alone and the presence of Pt further enhance the activity due to synergetic effect. The active species responsible for synergism on Pt/K-Al 2 O 3 are unstable and cannot be regenerated. Soot oxidation temperature decreases by about 150 o C with NO+O 2 exhaust feed gas and under lean conditions NSR system acts as catalysed soot filter (CSF). The reactions that are mainly responsible for decreasing soot oxidation temperature are: (1) soot oxidation with NO 2 followed by NO recycles to NO 2 , and (2) soot oxidation with O 2 assisted by NO 2 . Only a part of the stored NO x that is decomposed at high temperatures under lean conditions is found to be useful for soot oxidation. NO x storage capacity of NSR catalysts decreases upon ageing under soot oxidising conditions. This will lead to a decreased soot oxidation activity on stored nitrate decomposition. Pt/K-Al 2 O 3 catalyst is more active, but least stable compared with Pt/Ba-Al 2 O 3 . (author)

Selective carbon monoxide oxidation over Ag-based composite oxides

Energy Technology Data Exchange (ETDEWEB)

Guldur, C. [Gazi University, Ankara (Turkey). Chemical Engineering Department; Balikci, F. [Gazi University, Ankara (Turkey). Institute of Science and Technology, Environmental Science Department

2002-02-01

We report our results of the synthesis of 1 : 1 molar ratio of the silver cobalt and silver manganese composite oxide catalysts to remove carbon monoxide from hydrogen-rich fuels by the catalytic oxidation reaction. Catalysts were synthesized by the co-precipitation method. XRD, BET, TGA, catalytic activity and catalyst deactivation studies were used to identify active catalysts. Both CO oxidation and selective CO oxidation were carried out in a microreactor using a reaction gas mixture of 1 vol% CO in air and another gas mixture was prepared by mixing 1 vol% CO, 2 vol% O{sub 2}, 84 vol% H{sub 2}, the balance being He. 15 vol% CO{sub 2} was added to the reactant gas mixture in order to determine the effect of CO{sub 2}, reaction gases were passed through the humidifier to determine the effect of the water vapor on the oxidation reaction. It was demonstrated that metal oxide base was decomposed to the metallic phase and surface areas of the catalysts were decreased when the calcination temperature increased from 200{sup o}C to 500{sup o}C. Ag/Co composite oxide catalyst calcined at 200{sup o}C gave good activity at low temperatures and 90% of CO conversion at 180{sup o}C was obtained for the selective CO oxidation reaction. The addition of the impurities (CO{sub 2} or H{sub 2}O) decreased the activity of catalyst for selective CO oxidation in order to get highly rich hydrogen fuels. (author)

Selective catalytic oxidation of ammonia

Energy Technology Data Exchange (ETDEWEB)

Leppaelahti, J; Koljonen, T [VTT Energy, Espoo (Finland)

1997-12-31

In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

Selective catalytic oxidation of ammonia

Energy Technology Data Exchange (ETDEWEB)

Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

1996-12-31

In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

Improved methane removal in exhaust gas from biogas upgrading process using immobilized methane-oxidizing bacteria.

Science.gov (United States)

Sun, Meng-Ting; Yang, Zhi-Man; Fu, Shan-Fei; Fan, Xiao-Lei; Guo, Rong-Bo

2018-05-01

Methane in exhaust gas from biogas upgrading process, which is a greenhouse gas, could cause global warming. The biofilter with immobilized methane-oxidizing bacteria (MOB) is a promising approach for methane removal, and the selections of inoculated MOB culture and support material are vital for the biofilter. In this work, five MOB consortia were enriched at different methane concentrations. The MOB-20 consortium enriched at the methane concentration of 20.0% (v/v) was then immobilized on sponge and two particle sizes of volcanic rock in biofilters to remove methane in exhaust gas from biogas upgrading process. Results showed that the immobilized MOB performed more admirable methane removal capacity than suspended cells. The immobilized MOB on sponge reached the highest methane removal efficiency (RE) of 35%. The rough surface, preferable hydroscopicity, appropriate pore size and particle size of support material might favor the MOB immobilization and accordingly methane removal. Copyright © 2018 Elsevier Ltd. All rights reserved.

A quorum-sensing molecule acts as a morphogen controlling gas vesicle organelle biogenesis and adaptive flotation in an enterobacterium

Science.gov (United States)

Ramsay, Joshua P.; Williamson, Neil R.; Spring, David R.; Salmond, George P. C.

2011-01-01

Gas vesicles are hollow intracellular proteinaceous organelles produced by aquatic Eubacteria and Archaea, including cyanobacteria and halobacteria. Gas vesicles increase buoyancy and allow taxis toward air–liquid interfaces, enabling subsequent niche colonization. Here we report a unique example of gas vesicle-mediated flotation in an enterobacterium; Serratia sp. strain ATCC39006. This strain is a member of the Enterobacteriaceae previously studied for its production of prodigiosin and carbapenem antibiotics. Genes required for gas vesicle synthesis mapped to a 16.6-kb gene cluster encoding three distinct homologs of the main structural protein, GvpA. Heterologous expression of this locus in Escherichia coli induced copious vesicle production and efficient cell buoyancy. Gas vesicle morphogenesis in Serratia enabled formation of a pellicle-like layer of highly vacuolated cells, which was dependent on oxygen limitation and the expression of ntrB/C and cheY-like regulatory genes within the gas-vesicle gene cluster. Gas vesicle biogenesis was strictly controlled by intercellular chemical signaling, through an N-acyl homoserine lactone, indicating that in this system the quorum-sensing molecule acts as a morphogen initiating organelle development. Flagella-based motility and gas vesicle morphogenesis were also oppositely regulated by the small RNA-binding protein, RsmA, suggesting environmental adaptation through physiological control of the choice between motility and flotation as alternative taxis modes. We propose that gas vesicle biogenesis in this strain represents a distinct mechanism of mobility, regulated by oxygen availability, nutritional status, the RsmA global regulatory system, and the quorum-sensing morphogen. PMID:21873216

A quorum-sensing molecule acts as a morphogen controlling gas vesicle organelle biogenesis and adaptive flotation in an enterobacterium.

Science.gov (United States)

Ramsay, Joshua P; Williamson, Neil R; Spring, David R; Salmond, George P C

2011-09-06

Gas vesicles are hollow intracellular proteinaceous organelles produced by aquatic Eubacteria and Archaea, including cyanobacteria and halobacteria. Gas vesicles increase buoyancy and allow taxis toward air-liquid interfaces, enabling subsequent niche colonization. Here we report a unique example of gas vesicle-mediated flotation in an enterobacterium; Serratia sp. strain ATCC39006. This strain is a member of the Enterobacteriaceae previously studied for its production of prodigiosin and carbapenem antibiotics. Genes required for gas vesicle synthesis mapped to a 16.6-kb gene cluster encoding three distinct homologs of the main structural protein, GvpA. Heterologous expression of this locus in Escherichia coli induced copious vesicle production and efficient cell buoyancy. Gas vesicle morphogenesis in Serratia enabled formation of a pellicle-like layer of highly vacuolated cells, which was dependent on oxygen limitation and the expression of ntrB/C and cheY-like regulatory genes within the gas-vesicle gene cluster. Gas vesicle biogenesis was strictly controlled by intercellular chemical signaling, through an N-acyl homoserine lactone, indicating that in this system the quorum-sensing molecule acts as a morphogen initiating organelle development. Flagella-based motility and gas vesicle morphogenesis were also oppositely regulated by the small RNA-binding protein, RsmA, suggesting environmental adaptation through physiological control of the choice between motility and flotation as alternative taxis modes. We propose that gas vesicle biogenesis in this strain represents a distinct mechanism of mobility, regulated by oxygen availability, nutritional status, the RsmA global regulatory system, and the quorum-sensing morphogen.

Plasma-assisted partial oxidation of methane at low temperatures: numerical analysis of gas-phase chemical mechanism

Energy Technology Data Exchange (ETDEWEB)

Goujard, Valentin; Nozaki, Tomohiro; Yuzawa, Shuhei; Okazaki, Ken [Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, 1528552, Tokyo (Japan); Agiral, Anil, E-mail: tnozaki@mech.titech.ac.jp [Mesoscale Chemical Systems, MESA Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands)

2011-07-13

Methane partial oxidation was investigated using a plasma microreactor. The experiments were performed at 5 and 300 deg. C. Microreactor configuration allows an efficient evacuation of the heat generated by methane partial oxidation and dielectric barrier discharges, allowing at the same time a better temperature control. At 5 deg. C, liquid condensation of low vapour pressure compounds, such as formaldehyde and methanol, occurs. {sup 1}H-NMR analysis allowed us to demonstrate significant CH{sub 3}OOH formation during plasma-assisted partial oxidation of methane. Conversion and product selectivity were discussed for both temperatures. In the second part of this work, a numerical simulation was performed and a gas-phase chemical mechanism was proposed and discussed. From the comparison between the experimental results and the simulation it was found that CH{sub 3}OO{center_dot} formation has a determinant role in oxygenated compound production, since its fast formation disfavoured radical recombination. At 5 deg. C the oxidation leads mainly towards oxygenated compound formation, and plasma dissociation was the major phenomenon responsible for CH{sub 4} conversion. At 300 deg. C, higher CH{sub 4} conversion resulted from oxidative reactions induced by {center_dot}OH radicals with a chemistry predominantly oxidative, producing CO, H{sub 2}, CO{sub 2} and H{sub 2}O.

Crystallographic studies with xenon and nitrous oxide provide evidence for protein-dependent processes in the mechanisms of general anesthesia.

Science.gov (United States)

Abraini, Jacques H; Marassio, Guillaume; David, Helene N; Vallone, Beatrice; Prangé, Thierry; Colloc'h, Nathalie

2014-11-01

The mechanisms by which general anesthetics, including xenon and nitrous oxide, act are only beginning to be discovered. However, structural approaches revealed weak but specific protein-gas interactions. To improve knowledge, we performed x-ray crystallography studies under xenon and nitrous oxide pressure in a series of 10 binding sites within four proteins. Whatever the pressure, we show (1) hydrophobicity of the gas binding sites has a screening effect on xenon and nitrous oxide binding, with a threshold value of 83% beyond which and below which xenon and nitrous oxide, respectively, binds to their sites preferentially compared to each other; (2) xenon and nitrous oxide occupancies are significantly correlated respectively to the product and the ratio of hydrophobicity by volume, indicating that hydrophobicity and volume are binding parameters that complement and oppose each other's effects; and (3) the ratio of occupancy of xenon to nitrous oxide is significantly correlated to hydrophobicity of their binding sites. These data demonstrate that xenon and nitrous oxide obey different binding mechanisms, a finding that argues against all unitary hypotheses of narcosis and anesthesia, and indicate that the Meyer-Overton rule of a high correlation between anesthetic potency and solubility in lipids of general anesthetics is often overinterpreted. This study provides evidence that the mechanisms of gas binding to proteins and therefore of general anesthesia should be considered as the result of a fully reversible interaction between a drug ligand and a receptor as this occurs in classical pharmacology.

Morphology and oxide shell structure of iron nanoparticles grown by sputter-gas-aggregation

International Nuclear Information System (INIS)

Wang, C M; Baer, D R; Amonette, J E; Engelhard, M H; Qiang, Y; Antony, J

2007-01-01

The crystal faceting planes and oxide coating structures of core-shell structured iron/iron-oxide nanoparticles synthesized by a sputter-gas-aggregation process were studied using transmission electron microscopy (TEM), electron diffraction and Wulff shape construction. The particles grown by this process and deposited on a support in a room temperature process have been compared with particles grown and deposited at high temperature as reported in the literature. It has been found that the Fe nanoparticles formed at RT are invariantly faceted on the {100} lattice planes and truncated by the {110} planes at different degrees. A substantial fraction of particles are confined only by the 6{100} planes (not truncated by the {110} planes); this contrasts with the Fe particles formed at high temperature (HT) for which a predominance of {110} planes has been reported. Furthermore, at RT no particle was identified to be only confined by the 12{110} planes, which is relatively common for the particles formed at HT. The Fe cubes defined by the 6{100} planes show a characteristic inward relaxation along the and directions and the reason for this behaviour is not fully understood. The oxide shell on the Fe{100} plane maintains an orientation relationship: Fe(001) parallel Fe 3 O 4 (001) and Fe[100] parallel Fe 3 O 4 [110], which is the same as the oxide formed on a bulk Fe(001) through thermal oxidation. Orientation of the oxide that forms on the Fe{110} facets differs from that on Fe{001}: therefore, properties of core-shell structured Fe nanoparticle faceted primarily with one type of lattice plane may be fully different from that faceted with another type of lattice plane

Self-acting and hydrodynamic shaft seals

Science.gov (United States)

Ludwig, L. P.

1973-01-01

Self-acting and hydrodynamic seals are described. The analytical procedures are outlined for obtaining a seal force balance and the operating film thickness. Particular attention is given to primary ring response (seal vibration) to rotating seat face runout. This response analysis revealed three different vibration modes. Proposed applications of self-acting seals in gas turbine engines and in rocket vehicle turbopumps are described. Also experimental data on self-acting face seals operating under simulated gas turbine conditions are given; these data show the feasibility of operating the seal at conditions of 345 newtons per square centimeter (500 psi) and 152 meters per second (500 ft/sec) sliding speed.

Two-Dimensional Electron Gas at SrTiO3-Based Oxide Heterostructures via Atomic Layer Deposition

Directory of Open Access Journals (Sweden)

Sang Woon Lee

2016-01-01

Full Text Available Two-dimensional electron gas (2DEG at an oxide interface has been attracting considerable attention for physics research and nanoelectronic applications. Early studies reported the formation of 2DEG at semiconductor interfaces (e.g., AlGaAs/GaAs heterostructures with interesting electrical properties such as high electron mobility. Besides 2DEG formation at semiconductor junctions, 2DEG was realized at the interface of an oxide heterostructure such as the LaAlO3/SrTiO3 (LAO/STO heterojunction. The origin of 2DEG was attributed to the well-known “polar catastrophe” mechanism in oxide heterostructures, which consist of an epitaxial LAO layer on a single crystalline STO substrate among proposed mechanisms. Recently, it was reported that the creation of 2DEG was achieved using the atomic layer deposition (ALD technique, which opens new functionality of ALD in emerging nanoelectronics. This review is focused on the origin of 2DEG at oxide heterostructures using the ALD process. In particular, it addresses the origin of 2DEG at oxide interfaces based on an alternative mechanism (i.e., oxygen vacancies.

KINETIC STUDY OF SELECTIVE GAS-PHASE OXIDATION OF ISOPROPANOL TO ACETONE USING MONOCLINIC ZRO2 AS A CATALYST

Directory of Open Access Journals (Sweden)

Mohammad Sadiq

2015-08-01

Full Text Available Zirconia was prepared by a precipitation method and calcined at 723 K, 1023 K, and 1253 K in order to obtain monoclinic zirconia. The prepared zirconia was characterized by XRD, SEM, EDX, surface area and pore size analyzer, and particle size analyzer. Monoclinic ZrO2 as a catalyst was used for the gas-phase oxidation of isopropanol to acetone in a Pyrex-glass-flow-type reactor with a temperature range of 443 K - 473 K. It was found that monoclinic ZrO2 shows remarkable catalytic activity (68% and selectivity (100% for the oxidation of isopropanol to acetone. This kinetic study reveals that the oxidation of isopropanol to acetone follows the L-H mechanism.

Ammonia gas sensing property of gadolinium oxide using fiber optic gas sensor

Science.gov (United States)

Kumar, J. Santhosh; Ranganathan, B.; Sastikumar, D.

2017-05-01

The design of fiber optic sensor is based on a cladding modification methodology. A fiber-optic chemical sensor is developed by replacing a certain portion of the original cladding with a chemically sensitive material, specifically, calcinated gadolinium oxide (Gd2O3).Both the light absorption co-efficient and refractive index change upon exposure to chemical vapours of volatile organic compounds (VOCs) such as ammonia (NH3), ethanol (CH3CH2OH), and methanol (CH3OH). The spectral characteristics of the sensor were studied for different concentrations ranging from 0-500 ppm. These changes induced the optical intensity modulation of the transmitted optical signal. During interaction between the sensing material and VOCs, the output intensity is taken into account to detect the toxic VOCs present in the environment. This was systematically investigated by X-ray diffractometer (XRD) and SEM. The XRD analysis indicated that the calcinated Gd2O3 was formed in cubic structure with the crystallite size of 13 nm. The Gd2O3 nanorods with thickness ranging from 80 to 120 nm were confirmed from SEM. The ammonia gas response of the Gd2O3 sensor is presented. A model is proposed for understanding the spectral intensity variations.

Effect of exhaust gas recirculation on diesel engine nitrogen oxide reduction operating with jojoba methyl ester

Energy Technology Data Exchange (ETDEWEB)

Saleh, H.E. [Mechanical Power Department, Faculty of Engineering, Mattaria, Helwan University, 9 k Eltaaweniat, Nasr Road, P.O. Box 11718, Cairo (Egypt)

2009-10-15

Jojoba methyl ester (JME) has been used as a renewable fuel in numerous studies evaluating its potential use in diesel engines. These studies showed that this fuel is good gas oil substitute but an increase in the nitrogenous oxides emissions was observed at all operating conditions. The aim of this study mainly was to quantify the efficiency of exhaust gas recirculation (EGR) when using JME fuel in a fully instrumented, two-cylinder, naturally aspirated, four-stroke direct injection diesel engine. The tests were carried out in three sections. Firstly, the measured performance and exhaust emissions of the diesel engine operating with diesel fuel and JME at various speeds under full load are determined and compared. Secondly, tests were performed at constant speed with two loads to investigate the EGR effect on engine performance and exhaust emissions including nitrogenous oxides (NO{sub x}), carbon monoxide (CO), unburned hydrocarbons (HC) and exhaust gas temperatures. Thirdly, the effect of cooled EGR with high ratio at full load on engine performance and emissions was examined. The results showed that EGR is an effective technique for reducing NO{sub x} emissions with JME fuel especially in light-duty diesel engines. With the application of the EGR method, the CO and HC concentration in the engine-out emissions increased. For all operating conditions, a better trade-off between HC, CO and NO{sub x} emissions can be attained within a limited EGR rate of 5-15% with very little economy penalty. (author)

Sintering uranium oxide in the reaction product of hydrogen-carbon dioxide mixtures

International Nuclear Information System (INIS)

De Hollander, W.R.; Nivas, Y.

1975-01-01

Compacted pellets of uranium oxide alone or containing one or more additives such as plutonium dioxide, gadolinium oxide, titanium dioxide, silica, and alumina are heated to 900 to 1599 0 C in the presence of a mixture of hydrogen and carbon dioxide, either alone or with an inert carrier gas and held at the desired temperature in this atmosphere to sinter the pellets. The sintered pellets are then cooled in an atmosphere having an oxygen partial pressure of 10 -4 to 10 -18 atm of oxygen such as dry hydrogen, wet hydrogen, dry carbon monoxide, wet carbon monoxide, inert gases such as nitrogen, argon, helium, and neon and mixtures of ayny of the foregoing including a mixture of hydrogen and carbon dioxide. The ratio of hydrogen to carbon dioxide in the gas mixture fed to the furnace is controlled to give a ratio of oxygen to uranium atoms in the sintered particles within the range of 1.98:1 to about 2.10:1. The water vapor present in the reaction products in the furnace atmosphere acts as a hydrolysis agent to aid removal of fluoride should such impurity be present in the uranium oxide. (U.S.)

Scalable fractionation of iron oxide nanoparticles using a CO{sub 2} gas-expanded liquid system

Energy Technology Data Exchange (ETDEWEB)

Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B., E-mail: croberts@eng.auburn.edu [Auburn University, Department of Chemical Engineering (United States)

2015-10-15

Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO{sub 2} gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

High temperature oxidation behaviour of nanostructured cermet coatings in a mixed CO2 - O2 environment

Science.gov (United States)

Farrokhzad, M. A.; Khan, T. I.

2014-06-01

Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (α-Al2O3 and TiO2) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500°C, 600°C and 700°C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15% CO2, 10% O2 and 75% N2. This research investigates the effects of CO2 and O2 partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO2 at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO2 in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO2 acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO2 particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Ni-Ti compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings.

Experimental research on influencing factors of wet removal of NO from coal-fired flue gas by UV/H2O2 advanced oxidation process

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

Wet removal of NO from coal-fired flue gas by UV/H2O2 Advanced Oxidation Process (AOP) were investigated in a self-designed UV-bubble reactor. Several main influencing factors (UV intensity, H2O2 initial concentration, initial pH value, solution temperature, NO initial concentration, liquid-gas ratio and O2 percentage content) on the NO removal efficiency were studied. The results showed that UV intensity, H2O2 initial concentration, NO initial concentration and liquid-gas ratio are the main influencing factors. In the best conditions, the highest NO removal efficiency by UV/H2O2 advanced oxidation process could reach 82.9%. Based on the experimental study, the influencing mechanism of the relevant influencing factors were discussed in depth.

Short-Acting Gas Tamponade with Strict Face-Down Posturing for the Treatment of Idiopathic Macular Hole.

Science.gov (United States)

Gotzaridis, Stratos; Liazos, Efstathios; Petrou, Petros; Georgalas, Ilias

2017-01-01

A retrospective consecutive case series to evaluate the safety and efficacy of 25 gauge pars plana vitrectomy, ILM peeling, 20% SF 6 gas tamponade and strict posturing for the treatment of idiopathic full-thickness macular holes. We report the results of 106 consecutive eyes that underwent standard 25-gauge pars plana vitrectomy, brilliant peel-assisted internal limiting membrane peel, fluid:gas exchange with 20% SF 6 and strict posturing for one week. All patients were followed up at one week, one month, three months, and nine months postoperatively. Biomicroscopy at day 1 and biomicroscopy and OCT at week 1, months 1, 3, and 9 were used to assess macular hole status postoperatively. Pre- and postoperative logMAR visual acuity was compared. The macular hole was closed in 102/106 eyes postoperatively (96.2%). Four eyes showed unclosed macular holes and underwent additional SF 6 intravitreal injection and strict posturing for 10 days. All macular holes were eventually closed without the need of a second surgical procedure. Mean visual acuity improved from 0.63 logMAR preoperatively to 0.39 logMAR postoperatively. One case of retinal toxicity was reported due to accidental intravitreal injection of antibiotic. 25-gauge vitrectomy, ILM peel, and short-acting gas tamponade are highly effective for the treatment of macular holes. Additional intravitreal gas injection followed by strict posturing seems to be a simple and effective treatment for unclosed holes.

The gas-solid trickle-flow reactor for the catalytic oxidation of hydrogen sulphide: a trickle-phase model

NARCIS (Netherlands)

Verver, A.B.; van Swaaij, Willibrordus Petrus Maria

1987-01-01

The oxidation of H2S by O2 producing elemental sulphur has been studied at temperatures of 100–300°C and at atmospheric pressure in a laboratory-scale gas-solid trickle-flow reactor. In this reactor one of the reaction products, i.e. sulphur, is removed continuously by flowing solids. A porous,

Molybdenum-based additives to mixed-metal oxides for use in hot gas cleanup sorbents for the catalytic decomposition of ammonia in coal gases

Science.gov (United States)

Ayala, Raul E.

1993-01-01

This invention relates to additives to mixed-metal oxides that act simultaneously as sorbents and catalysts in cleanup systems for hot coal gases. Such additives of this type, generally, act as a sorbent to remove sulfur from the coal gases while substantially simultaneously, catalytically decomposing appreciable amounts of ammonia from the coal gases.

Kinetics of solid-gas reactions characterized by scanning AC nano-calorimetry with application to Zr oxidation

International Nuclear Information System (INIS)

Xiao, Kechao; Lee, Dongwoo; Vlassak, Joost J.

2014-01-01

Scanning AC nano-calorimetry is a recently developed experimental technique capable of measuring the heat capacity of thin-film samples of a material over a wide range of temperatures and heating rates. Here, we describe how this technique can be used to study solid-gas phase reactions by measuring the change in heat capacity of a sample during reaction. We apply this approach to evaluate the oxidation kinetics of thin-film samples of zirconium in air. The results confirm parabolic oxidation kinetics with an activation energy of 0.59 ± 0.03 eV. The nano-calorimetry measurements were performed using a device that contains an array of micromachined nano-calorimeter sensors in an architecture designed for combinatorial studies. We demonstrate that the oxidation kinetics can be quantified using a single sample, thus enabling high-throughput mapping of the composition-dependence of the reaction rate.

Death from Nitrous Oxide.

Science.gov (United States)

Bäckström, Björn; Johansson, Bengt; Eriksson, Anders

2015-11-01

Nitrous oxide is an inflammable gas that gives no smell or taste. It has a history of abuse as long as its clinical use, and deaths, although rare, have been reported. We describe two cases of accidental deaths related to voluntary inhalation of nitrous oxide, both found dead with a gas mask covering the face. In an attempt to find an explanation to why the victims did not react properly to oncoming hypoxia, we performed experiments where a test person was allowed to breath in a closed system, with or without nitrous oxide added. Vital signs and gas concentrations as well as subjective symptoms were recorded. The experiments indicated that the explanation to the fact that neither of the descendents had reacted to oncoming hypoxia and hypercapnia was due to the inhalation of nitrous oxide. This study raises the question whether nitrous oxide really should be easily, commercially available. © 2015 American Academy of Forensic Sciences.

Catalytic oxidation using nitrous oxide

Directory of Open Access Journals (Sweden)

Juan Carlos Beltran-Prieto

2017-01-01

Full Text Available Nitrous oxide is a very inert gas used generally as oxidant as it offers some advantage compared with other oxidants such as O2 but a considerably higher temperature (> 526 °C is often required. For particular cases such as the oxidation of sugar alcohols, especially for the oxidation of primary alcohols to aldehydes, N2O has the advantage over O2 of a higher reaction selectivity. In the present paper we present the modelling of oxidation reaction of sugar alcohols using an oxidizing agent in low concentrations, which is important to suppress subsequent oxidation reactions due to the very low residual concentrations of the oxidizing agent. For orientation experiments we chose nitrous oxide generated by thermal decomposition of ammonium nitrate. Kinetic modeling of the reaction was performed after determination of the differential equations that describe the system under study.

Nitric Oxide: A Multitasked Signaling Gas in Plants

KAUST Repository

Domingos, Patricia

2014-12-01

Nitric oxide (NO) is a gaseous reactive oxygen species (ROS) that has evolved as a signaling hormone in many physiological processes in animals. In plants it has been demonstrated to be a crucial regulator of development, acting as a signaling molecule present at each step of the plant life cycle. NO has also been implicated as a signal in biotic and abiotic responses of plants to the environment. Remarkably, despite this plethora of effects and functional relationships, the fundamental knowledge of NO production, sensing, and transduction in plants remains largely unknown or inadequately characterized. In this review we cover the current understanding of NO production, perception, and action in different physiological scenarios. We especially address the issues of enzymatic and chemical generation of NO in plants, NO sensing and downstream signaling, namely the putative cGMP and Ca2+ pathways, ion-channel activity modulation, gene expression regulation, and the interface with other ROS, which can have a profound effect on both NO accumulation and function. We also focus on the importance of NO in cell–cell communication during developmental processes and sexual reproduction, namely in pollen tube guidance and embryo sac fertilization, pathogen defense, and responses to abiotic stress.

Thin film deposition and characterization of pure and iron-doped electron-beam evaporated tungsten oxide for gas sensors

Energy Technology Data Exchange (ETDEWEB)

Tesfamichael, Tuquabo, E-mail: t.tesfamichael@qut.edu.a [Faculty of Built Environment and Engineering, School of Engineering Systems, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000 (Australia); Arita, Masashi [Graduate School of Information Science and Technology, Hokkaido University, Kita-14, Nishi-9, Kita-ku, Sapporo, 060-0814 (Japan); Bostrom, Thor [Faculty of Science and Technology, School of Physical and Chemical Sciences, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000 (Australia); Bell, John [Centre for Built Environment and Engineering Research, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000 (Australia)

2010-06-30

Pure tungsten oxide (WO{sub 3}) and iron-doped (10 at.%) tungsten oxide (WO{sub 3}:Fe) nanostructured thin films were prepared using a dual crucible Electron Beam Evaporation (EBE) technique. The films were deposited at room temperature under high vacuum onto glass as well as alumina substrates and post-heat treated at 300 {sup o}C for 1 h. Using Raman spectroscopy the as-deposited WO{sub 3} and WO{sub 3}:Fe films were found to be amorphous, however their crystallinity increased after annealing. The estimated surface roughness of the films was similar (of the order of 3 nm) to that determined using Atomic Force Microscopy (AFM). As observed by AFM, the WO{sub 3}:Fe film appeared to have a more compact surface as compared to the more porous WO{sub 3} film. X-ray photoelectron spectroscopy analysis showed that the elemental stoichiometry of the tungsten oxide films was consistent with WO{sub 3}. A slight difference in optical band gap energies was found between the as-deposited WO{sub 3} (3.22 eV) and WO{sub 3}:Fe (3.12 eV) films. The differences in the band gap energies of the annealed films were significantly higher, having values of 3.12 eV and 2.61 eV for the WO{sub 3} and WO{sub 3}:Fe films respectively. The heat treated films were investigated for gas sensing applications using noise spectroscopy. It was found that doping of Fe to WO{sub 3} produced gas selectivity but a reduced gas sensitivity as compared to the WO{sub 3} sensor.

Process for removal of sulfur oxides from hot gases

International Nuclear Information System (INIS)

Bauerle, G. L.; Kohl, A. L.

1984-01-01

A process for the removal of sulfur oxides from two gas streams containing the same. One gas stream is introduced into a spray dryer zone and contacted with a finely dispersed spray of an aqueous medium containing an absorbent for sulfur oxides. The aqueous medium is introduced at a controlled rate so as to provide water to the gas in an amount to produce a cooled product gas having a temperature at least 7 0 C. above its adiabatic saturation temperature and from about 125-300% of the stoichiometric amount of absorbent required to react with the sulfur oxides to be removed from the gas stream. The effluent from the spray dryer zone comprises a gas stream of reduced sulfur oxide content and contains entrained dry particulate reaction products including unreacted absorbent. This gas stream is then introduced into a particulate removal zone from which is withdrawn a gas stream substantially free of particles and having a reduced sulfur oxide content. the dry particulate reaction products are collected and utilized as a source of absorbent for a second aqueous scrubbing medium containing unreacted absorbent for the sulfur oxides. An effluent gas stream is withdrawn from the aqueous scrubbing zone and comprises a water-saturated gas stream of reduced sulfur oxide content and substantially free of particles. The effluent gas streams from the particulate removal zone and the aqueous scrubbing zone are combined in such proportions that the combined gas stream has a temperature above its adiabatic saturation temperature

Gas sensing in 2D materials

Science.gov (United States)

Yang, Shengxue; Jiang, Chengbao; Wei, Su-huai

2017-06-01

Two-dimensional (2D) layered inorganic nanomaterials have attracted huge attention due to their unique electronic structures, as well as extraordinary physical and chemical properties for use in electronics, optoelectronics, spintronics, catalysts, energy generation and storage, and chemical sensors. Graphene and related layered inorganic analogues have shown great potential for gas-sensing applications because of their large specific surface areas and strong surface activities. This review aims to discuss the latest advancements in the 2D layered inorganic materials for gas sensors. We first elaborate the gas-sensing mechanisms and introduce various types of gas-sensing devices. Then, we describe the basic parameters and influence factors of the gas sensors to further enhance their performance. Moreover, we systematically present the current gas-sensing applications based on graphene, graphene oxide (GO), reduced graphene oxide (rGO), functionalized GO or rGO, transition metal dichalcogenides, layered III-VI semiconductors, layered metal oxides, phosphorene, hexagonal boron nitride, etc. Finally, we conclude the future prospects of these layered inorganic materials in gas-sensing applications.

Energy Policy Act

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Energy Policy Act (EPA) addresses energy production in the United States, including: (1) energy efficiency; (2) renewable energy; (3) oil and gas; (4) coal; (5)...

Iodine removal from a gas phase

International Nuclear Information System (INIS)

Vikis, A. Ch.

1982-01-01

Iodine, e.g. radioactive iodine, present as one or more organic iodides, optionally with elemental iodine, in a gas phase (e.g. air) are removed by photochemically decomposing the organic iodides to elemental iodine, reacting the iodine produced, and any initially present with excess ozone, preferably photochemically produced in situ in the gas phase to produce solid iodine oxides, and removing the solid oxides from the gas phase. (author)

Iodine removal from a gas phase

International Nuclear Information System (INIS)

Vikis, A.C.

1984-01-01

Iodine, e.g. radioactive iodine, present as one or more organic iodides, optionally with elemental iodine, in a gas phase (e.g. air) are removed by photochemically decomposing the organic iodides to elemental iodine, reacting the iodine produced, and any initially present with excess ozone, preferably photochemically produced in situ in the gas phase to produce solid iodine oxides, and removing the solid oxides from the gas phase

Hydroperoxide Measurements During Low-Temperature Gas-Phase Oxidation of n-Heptane and n-Decane

KAUST Repository

Rodriguez, Anne

2017-02-13

A wide range of hydroperoxides (C-C alkyl hydroperoxides, C-C alkenyl hydroperoxides, C ketohydroperoxides, and hydrogen peroxide (HO)), as well as ketene and diones, have been quantified during the gas-phase oxidation of n-heptane. Some of these species, as well as C alkenyl hydroperoxides and ketohydroperoxides, were also measured during the oxidation of n-decane. These experiments were performed using an atmospheric-pressure jet-stirred reactor at temperatures from 500 to 1100 K and one of three analytical methods, time-of-flight mass spectrometry combined with tunable synchrotron photoionization with a molecular beam sampling: time-of-flight mass spectrometry combined with laser photoionization with a capillary tube sampling, continuous wave cavity ring-down spectroscopy with sonic probe sampling. The experimental temperature at which the maximum mole fraction is observed increases significantly for alkyl hydroperoxides, alkenyl hydroperoxides, and then more so again for hydrogen peroxide, compared to ketohydroperoxides. The influence of the equivalence ratio from 0.25 to 4 on the formation of these peroxides has been studied during n-heptane oxidation. The up-to-date detailed kinetic oxidation models for n-heptane and for n-decane found in the literature have been used to discuss the possible pathways by which these peroxides, ketene, and diones are formed. In general, the model predicts well the reactivity of the two fuels, as well as the formation of major intermediates. (Figure Presented).

Hydroperoxide Measurements During Low-Temperature Gas-Phase Oxidation of n-Heptane and n-Decane

KAUST Repository

Rodriguez, Anne; Herbinet, Olivier; Meng, Xiangzan; Fittschen, Christa; Wang, Zhandong; Xing, Lili; Zhang, Lidong; Battin-Leclerc, Fré dé rique

2017-01-01

A wide range of hydroperoxides (C-C alkyl hydroperoxides, C-C alkenyl hydroperoxides, C ketohydroperoxides, and hydrogen peroxide (HO)), as well as ketene and diones, have been quantified during the gas-phase oxidation of n-heptane. Some of these species, as well as C alkenyl hydroperoxides and ketohydroperoxides, were also measured during the oxidation of n-decane. These experiments were performed using an atmospheric-pressure jet-stirred reactor at temperatures from 500 to 1100 K and one of three analytical methods, time-of-flight mass spectrometry combined with tunable synchrotron photoionization with a molecular beam sampling: time-of-flight mass spectrometry combined with laser photoionization with a capillary tube sampling, continuous wave cavity ring-down spectroscopy with sonic probe sampling. The experimental temperature at which the maximum mole fraction is observed increases significantly for alkyl hydroperoxides, alkenyl hydroperoxides, and then more so again for hydrogen peroxide, compared to ketohydroperoxides. The influence of the equivalence ratio from 0.25 to 4 on the formation of these peroxides has been studied during n-heptane oxidation. The up-to-date detailed kinetic oxidation models for n-heptane and for n-decane found in the literature have been used to discuss the possible pathways by which these peroxides, ketene, and diones are formed. In general, the model predicts well the reactivity of the two fuels, as well as the formation of major intermediates. (Figure Presented).

High temperature oxidation behaviour of nanostructured cermet coatings in a mixed CO2 – O2 environment

International Nuclear Information System (INIS)

Farrokhzad, M A; Khan, T I

2014-01-01

Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (α-Al 2 O3 and TiO 2 ) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500°C, 600°C and 700°C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15% CO 2 , 10% O 2 and 75% N 2 . This research investigates the effects of CO 2 and O 2 partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO 2 at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO 2 in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO2 acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO 2 particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Ni-Ti compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings

Environmental requirements for oil and gas operations in Saskatchewan

International Nuclear Information System (INIS)

Nystuen, L.J.

1997-01-01

The administration and regulation of environmental issues regarding the oil and gas industry in Saskatchewan were discussed. The political and cultural differences in Saskatchewan that make environmental processes distinct from its neighbouring jurisdictions were described. The following Saskatchewan legislation deals with environmental requirements: Environmental Management and Protection Act, Environmental Assessment Act, Oil and Gas Conservation Act, Wildlife Habitat Protection Act, Clean Air Act, Planning and Development Act, Forest Act, Water Corporation Act, Heritage Property Act, and Parks Act. The Saskatchewan Department of Energy and Mines (SEM) is the primary regulator of the upstream oil and gas industry. It regulates the construction, operation, reporting and abandonment requirements for oilfield operations. SEM also manages crude oil prior to refining and manages the wastes contaminated with crude oil. Provisions of the relevant Acts regarding drilling in environmentally sensitive areas, flaring requirements, transporting and disposing of oilfield wastes, road-building, operating restrictions, emergency response plans, spill clean-up responsibilities, well abandonment and site reclamation responsibilities were discussed. 8 refs., 2 tabs

Enhanced visible-light photocatalysis and gas sensor properties of polythiophene supported tin doped titanium nanocomposite

Science.gov (United States)

Chandra, M. Ravi; Siva Prasada Reddy, P.; Rao, T. Siva; Pammi, S. V. N.; Siva Kumar, K.; Vijay Babu, K.; Kiran Kumar, Ch.; Hemalatha, K. P. J.

2017-06-01

The polythiophene supported tin doped titanium nanocomposites (PTh/Sn-TiO2) were synthesized by modified sol-gel process through oxidative polymerization of thiophene. The fourier transform infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectroscopy (UV-DRS) analysis confirms the existence of synergetic interaction between metal oxide and polymer along with extension of absorption edge to visible region. The composites are found to be in spherical form with core-shell structure, which is confirmed by scanning electron spectroscopy (SEM) and transmission electron microscopy (TEM) images, the presence of all respective elements of composite are proven by energy-dispersive X-ray spectroscopy (EDX) analysis. The importance of polythiophene on surface of metal oxide has been were studied as a function of photocatalytic activity for degradation of organic pollutant congo red and gas sensor behavior towards liquid petroleum gas (LPG). All the composites are photocatalytically active and the composite with 1.5 wt% thiophene degrades the pollutant congo red within 120 min when compared to remaining catalysts under visible light irradiation. On the other hand, same composite have shown potential gas sensor properties towards LPG at 300 °C. Considering all the results, it can be noted that polythiophene acts as good sensitizer towards LPG and supporter for the tin doped titania that improve the photocatalytic activity under visible light.

Design optimisation of a hybrid solid oxide fuel cell and gas turbine power generation system

Energy Technology Data Exchange (ETDEWEB)

Williams, G.J.; Siddle, A.; Pointon, K.

2001-07-01

The objectives of the combined ALSTOM Power Technology and Advantica Technologies project are reported as: (a) to design a gas turbine (GT) unit compatible with a solid oxide fuel cell (SOFC) in a high efficiency power system and aimed at the Distributed Power application range of 1-20MW, and (b) to identify the main features and components of a 'Proof of Concept' hybrid unit of output around 0.1MW, based on existing or near-market technology. The study showed: (i) while the potential for high efficiency SOFC + GT hybrid cycles is clear, little effort has been put into the design of the gas turbine and some other components and (ii) there is room for commercial exploitation in the areas of both component manufacture and system supply.

Oxidative potential of gas phase combustion emissions - An underestimated and potentially harmful component of air pollution from combustion processes

Science.gov (United States)

Stevanovic, S.; Vaughan, A.; Hedayat, F.; Salimi, F.; Rahman, M. M.; Zare, A.; Brown, R. A.; Brown, R. J.; Wang, H.; Zhang, Z.; Wang, X.; Bottle, S. E.; Yang, I. A.; Ristovski, Z. D.

2017-06-01

The oxidative potential (OP) of the gas phase is an important and neglected aspect of environmental toxicity. Whilst prolonged exposure to particulate matter (PM) associated reactive oxygen species (ROS) have been shown to lead to negative health effects, the potential for compounds in gas phase to cause similar effects is yet to be understood. In this study we describe: the significance of the gas phase OP generated through vehicle emissions; discuss the origin and evolution of species contributing to measured OP; and report on the impact of gas phase OP on human lung cells. The model aerosol for this study was exhaust emitted from a Euro III Common-rail diesel engine fuelled with different blends of diesel and biodiesel. The gas phase of these emissions was found to be potentially as hazardous as the particle phase. Fuel oxygen content was found to negatively correlate with the gas phase OP, and positively correlate with particle phase OP. This signifies a complex interaction between reactive species present in gas and particle phase. Furthermore, this interaction has an overarching effect on the OP of both particle and gas phase, and therefore the toxicity of combustion emissions.

A novel surface-enhanced Raman scattering (SERS) detection for natural gas exploration using methane-oxidizing bacteria.

Science.gov (United States)

Liang, Weiwei; Chen, Qiao; Peng, Fang; Shen, Aiguo; Hu, Jiming

2018-07-01

Methane-oxidizing bacteria (MOB), a unique group of Gram-negative bacteria utilizing methane as a sole source of carbon and energy, have been proved to be a biological indicator for gas prospecting. Field and cultivation-free detection of MOB is important but still challenging in current microbial prospecting of oil and gas (MPOG) system. Herein, SERS was used for the first time to our knowledge to investigate two species of methanotrophs and four closely relevant bacteria that universally coexisted in the upper soil of natural gas. A special but very simple approach was utilized to make silver nanoparticles (Ag NPs) sufficiently contact with every single bacterial cell, and highly strong and distinct Raman signals free from any native fluorescence have been obtained, and successfully utilized for distinguishing MOB from other species. A more convincing multi-Raman criterion based on single Raman bands, and further the entire Raman spectrum in combination with statistical analysis (e.g., principal component analysis (PCA)), which were found capable of classifying MOB related bacterial cells in soil with an accuracy of 100%. This study therefore demonstrated sensitive and rapid SERS measurement technique accompanied by complete Raman database of various gas reservoirs related bacteria could aid field exploration of natural gas reservoir. Copyright © 2018 Elsevier B.V. All rights reserved.

Cryogenic treatment of gas

Science.gov (United States)

Bravo, Jose Luis [Houston, TX; Harvey, III, Albert Destrehan; Vinegar, Harold J [Bellaire, TX

2012-04-03

Systems and methods of treating a gas stream are described. A method of treating a gas stream includes cryogenically separating a first gas stream to form a second gas stream and a third stream. The third stream is cryogenically contacted with a carbon dioxide stream to form a fourth and fifth stream. A majority of the second gas stream includes methane and/or molecular hydrogen. A majority of the third stream includes one or more carbon oxides, hydrocarbons having a carbon number of at least 2, one or more sulfur compounds, or mixtures thereof. A majority of the fourth stream includes one or more of the carbon oxides and hydrocarbons having a carbon number of at least 2. A majority of the fifth stream includes hydrocarbons having a carbon number of at least 3 and one or more of the sulfur compounds.

Environmental and economic benefits of natural gas use for pollution control

International Nuclear Information System (INIS)

Dey, P.R.; Berkau, E.E.; Schnelle, K.B.

1993-01-01

One of the primary goals of this research effort was to document and compare the economic and environment benefits of using natural gas for pollution control in boilers, furnaces and internal combustion engines, with conventional control technologies. The study indicated that replacement of 15% of the coal used in coal-fired boilers employed in the generation of electric power in the US, with natural gas, would considerably reduce the emissions of acid rain precursors such as sulfur and nitrogen oxides, and do so in a cost-effect manner. The reductions achieved were also in concordance with the reductions in sulfur dioxide emissions mandated by the new Clean Air Act (CAA) Amendments of 1990. The combustion of natural gas would also produce less carbon dioxide as compared to the combustion of coal with an equivalent amount of heat content. Carbon dioxide is a greenhouse gas, i.e., it is believed to play a major role in global warming. Natural gas technology therefore presents a cost-effective step in the eventual mitigation of two of the main environmental problems presently facing us, acid rain, and global warming

Non-catalytic plasma-arc reforming of natural gas with carbon dioxide as the oxidizing agent for the production of synthesis gas or hydrogen

OpenAIRE

Blom, P.W.E.; Basson, G.W.

2013-01-01

The world’s energy consumption is increasing constantly due to the growing population of the world. The increasing energy consumption has a negative effect on the fossil fuel reserves of the world. Hydrogen has the potential to provide energy for all our needs by making use of fossil fuel such as natural gas and nuclear-based electricity. Hydrogen can be produced by reforming methane with carbon dioxide as the oxidizing agent. Hydrogen can be produced in a Plasma-arc reforming ...

Gas-phase photocatalysis in μ-reactors

DEFF Research Database (Denmark)

Vesborg, Peter Christian Kjærgaard; Olsen, Jakob Lind; Henriksen, Toke Riishøj

2010-01-01

Gas-phase photocatalysis experiments may benefit from the high sensitivity and good time response in product detection offered by μ-reactors. We demonstrate this by carrying out CO oxidation and methanol oxidation over commercial TiO2 photocatalysts in our recently developed high-sensitivity reac......Gas-phase photocatalysis experiments may benefit from the high sensitivity and good time response in product detection offered by μ-reactors. We demonstrate this by carrying out CO oxidation and methanol oxidation over commercial TiO2 photocatalysts in our recently developed high...

The Clean Air Act Amendments of 1990

International Nuclear Information System (INIS)

Mosby, R.C.

1991-01-01

The natural gas liquids industry and specifically the gas processing business has not been rosy the last several years. processors have been faced with low NGL prices, high inventories and more regulations which have forced product margins to all time lows and have resulted in plant closings, mergers and a determined search for those processors that are left for ways to make ends meet until times get better. Whether a barometer for the future or merely a fluke in the economy, things got better in 1990. Last year represented a change for the positive in all the indicators characterizing the gas processing business. An early winter in 1989, propane distribution problems, overall increases in petrochemical demand for NGLs and the fear brought on by events in Kuwait all contributed to changes in the marketplace. For the gas processor, these events combined with relatively low natural gas prices to produce wider processing margins and a degree of prosperity. The biggest regulatory event in 1990 however was without a doubt the Clean Air Act Amendments. These sweeping changes to the 1970 Clean Air Act promise to affect the economy and public health well into the next century. The purpose of this paper is to examine first the major provisions of the Clean Air Act Amendments of 1990 and then relate those anticipated changes to the gas processing industry. As will be examined later, the Amendments will create both threats and opportunities for gas processors

Experimental and numerical investigation of the catalytic partial oxidation of methane to synthesis gas for power generation applications[Dissertation 17183

Energy Technology Data Exchange (ETDEWEB)

Schneider, A.

2007-07-01

The present work addresses the catalytic partial oxidation (CPO) of methane to synthesis gas, with particular emphasis on power generation applications. A combined experimental and numerical investigation of methane partial oxidation to synthesis gas (H{sub 2}, CO) over rhodium-based catalysts has been carried out at pressures of up to 10 bar. The reactivity of the produced hydrogen and the suitably-low light-off temperatures of the CPO reactor, greatly facilitate operation of power generation gas turbines with reduced NO{sub x} emissions, stable operation with low calorific value fuels, and new combustion strategies for efficient CO{sub 2} capture. Those strategies utilize CPO of methane with oxygen (separated from air) and large exhaust gas recycle (H{sub 2}O and CO{sub 2}). An optically accessible catalytic channel-flow reactor was used to carry out Raman spectroscopy of major gas-phase species and laser induced fluorescence (LIF) of formaldehyde, in order to gain fundamental information on the catalytic and gas-phase chemical pathways. Transverse concentration profiles measured by the spontaneous Raman scattering technique determined the catalytic reactivity, while the LIF provided flame shapes and anchoring positions that, in turn, characterized the gaseous reactivity. Comparison between measurements and 2-D CFD computations, led to the validation of detailed catalytic and gas-phase reaction mechanisms. Experiments in a subscale gas-turbine honeycomb catalytic reactor have shown that the foregoing reaction mechanisms were also appropriate under gas-turbine relevant conditions with short reactant residence times. The light-off behavior of the subscale honeycomb reactor was reproduced by transient 2-D CFD computations. Ignition and extinction in CPO was studied. It was shown that, despite the chemical impact of the H{sub 2}O diluent during the transient catalytic ignition event, the light-off times themselves were largely unaffected by the exhaust gas dilution

Effects of hydrogen gas on properties of tin-doped indium oxide films deposited by radio frequency magnetron sputtering method

International Nuclear Information System (INIS)

Kim, Do-Geun; Lee, Sunghun; Lee, Gun-Hwan; Kwon, Sik-Chol

2007-01-01

Tin-doped indium oxide (ITO) films were deposited at ∼ 70 deg. C of substrate temperature by radio frequency magnetron sputtering method using an In 2 O 3 -10% SnO 2 target. The effect of hydrogen gas ratio [H 2 / (H 2 + Ar)] on the electrical, optical and mechanical properties was investigated. With increasing the amount of hydrogen gas, the resistivity of the samples showed the lowest value of 3.5 x 10 -4 Ω.cm at the range of 0.8-1.7% of hydrogen gas ratio, while the resistivity increases over than 2.5% of hydrogen gas ratio. Hall effect measurements explained that carrier concentration and its mobility are strongly related with the resistivity of ITO films. The supplement of hydrogen gas also reduced the residual stress of ITO films up to the stress level of 110 MPa. The surface roughness and the crystallinity of the samples were investigated by using atomic force microscopy and x-ray diffraction, respectively

In vitro determination of oxidation of atmospheric tritium gas in vegetation and soil in Ibaraki and Gifu, Japan

International Nuclear Information System (INIS)

Ichimasa, Michiko; Ichimasa, Yusuke; Suzuki, Masatomo; Obayashi, Haruo; Sakuma, Youichi

1999-01-01

To quantify the rate of oxidation of tritium gas (referred to as HT) to tritiated water in the environment, various woody and herbaceous plant leaves and roots, mosses and lichens taken from a forest and fields in Ibaraki prefecture, and a forest in Toki, Gifu prefecture, were investigated as to their ability to oxidize atmospheric HT in vitro experiments. The HT oxidation activity in vegetation was compared with that in the surrounding surface soil (0-5 cm in depth). The rate of oxidation of HT in woody plant leaves including pine needles was extremely low, only about 1/10000-1/1000 that in the surface soil, as well as in herbaceous plant leaves with some exceptions (Phalaris arundinacea and Vaccinium smallii), whereas the rate in mosses and lichens was 50-500 times that in pine needles. The HT oxidation activity in roots of several plants including Phalaris arundinacea, Pieris japonica and Lespedeza homoloba was quite high and comparable to that in the surrounding surface soil. These results suggest that mosses, lichens and the leaves or roots of particular plants with high HT oxidation activity can be used to monitor the accidental release of HT into the environment. (author)

Theoretical treatment of the spin-orbit coupling in the rare gas oxides NeO, ArO, KrO, and XeO

Science.gov (United States)

Langhoff, S. R.

1980-01-01

Off-diagonal spin-orbit matrix elements are calculated as a function of internuclear distance for the rare gas oxides NeO, ArO, KrO, and XeO using the full microscopic spin-orbit Hamiltonian, including all one- and two-electron integrals, and POL-CI wave functions comparable to those of Dunning and Hay (1977). A good agreement was found when comparing these results in detail with the calculations of Cohen, Wadt and Hay (1979) that utilize an effective one-electron one-center spin-orbit operator. For the rare gas oxide molecules, it is suggested that the numerical results are a more sensitive test of the wave functions (particularly to the extent of charge transfer) than the exact evaluation of all terms in the full spin-orbit operator.

Slow photon amplification of gas-phase ethanol photo-oxidation in titania inverse opal photonic crystals

Energy Technology Data Exchange (ETDEWEB)

Jovic, Vedran, E-mail: vjov001@aucklanduni.ac.nz [School of Chemical Sciences, Science Centre, Building 301, 23 Symonds Street, Auckland 92019 (New Zealand); Idriss, Hicham, E-mail: IdrissH@sabic.com [Corporate Research and Development (CRD), Saudi Basic Industries Corporation (SABIC) at KAUST (Saudi Arabia); Waterhouse, Geoffrey I.N., E-mail: g.waterhouse@auckland.ac.nz [School of Chemical Sciences, Science Centre, Building 301, 23 Symonds Street, Auckland 92019 (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Dodd Walls Centre for Photonic and Quantum Technologies (New Zealand)

2016-11-10

Here we describe the successful fabrication of six titania inverse opal (TiO{sub 2} IO) photocatalysts with fcc[1 1 1] pseudo photonic band gaps (PBGs) tuned to span the UV–vis region. Photocatalysts were fabricated by a colloidal crystal templating and sol-gel approach – a robust and highly applicable bottom-up scheme which allowed for precise control over the geometric and optical properties of the TiO{sub 2} IO photocatalysts. Optical properties of the TiO{sub 2} IO thin films were investigated in detail by UV–vis transmittance and reflectance measurements. The PBG along the fcc[1 1 1] direction in the TiO{sub 2} IOs was dependent on the inter-planar spacing in the [1 1 1] direction, the incident angle of light and the refractive index of the medium filling the macropores in the IOs, in agreement with a modified Bragg’s law expression. Calculated photonic band structures for the photocatalysts revealed a PBG along the Γ → L direction at a/λ ∼ 0.74, in agreement with the experimental optical data. By coupling the low frequency edge of the PBG along the [1 1 1] direction with the electronic absorption edge of anatase TiO{sub 2}, a two-fold enhancement in the rate of gas phase ethanol photo-oxidation in air was achieved. This enhancement appears to be associated with a ‘slow photon’ effect that acts to both enhance TiO{sub 2} absorption and inhibit spontaneous emission (i.e. suppress electron-hole pair recombination).

Electric plants to gas, influence of both Mineral Matter and Air Oxidation in coal pyrolysis

International Nuclear Information System (INIS)

Mondragon, F.; Jaramillo, A.; Quintero, G.

1995-01-01

In this work some coal samples from different Colombia's deposits are analyzed. In first stage, material matter is removed from coal by acid treatment with HF/HCl, and aerial oxidation of coal is made with air in oven to 150 Centigrade degree temperature. In second stage, pyrolysis is carried out in two different techniques: 1. Thermogravimetric Analysis (TGA) and 2. Programmed Temperature Pyrolysis (PTP) in a pyrolyzer equipped with a quadrupole mass spectrometer. In both techniques, the coal samples are heated in different rates to 650 Centigrade degree. During PTP trials the evolution of CH4, H2S, hydrocarbons (m/z=42), CO2, benzene and toluene are monitored. Studied coal samples showed: 1). A gas conversion range between 48.8% to 21.8%; 2). A decrease in the gas conversion between 2% to 4%, when oxidation it is applied; 3). The temperature at the one which is presented the maximum evolution of CH4 is similar for all coal samples; 4). The maximum evolution of H2S depends on mineral matter composition, occurs between 480 to 550 Centigrade degrees and is presented due to pyrite decomposition. 5). The evolution of CO2 occurs between 100 to 650 Centigrade degree, its production is generated in different stage of the mentioned temperature range, and in some coal samples is presented due to inorganic origin

Comparative study of the influence of the gas injection system on the Nd:yttrium-aluminum-garnet laser cutting of advanced oxide ceramics

International Nuclear Information System (INIS)

Quintero, F.; Pou, J.; Lusquinos, F.; Boutinguiza, M.; Soto, R.; Perez-Amor, M.

2003-01-01

Cutting of advanced oxide ceramics is still a difficult task. In this work, the possibility to effectively cut them using a Nd:YAG laser guided by an optical fiber is demonstrated. The key points are the aerodynamic interactions of the assist gas jet in the fusion laser cutting of ceramics. A comprehensive study of the influence of these aerodynamic interactions on the laser cutting of advanced oxide ceramics has been carried out. The characteristics of the heat affected zone (HAZ) were studied related to the efficiency of the assist gas to eject the molten material. It has been demonstrated that the HAZ can be avoided with a suitable design of the gas injection system combined with an appropriate selection of the values of the processing parameters. With the aim of improving the efficiency of the assist gas injection system, a new cutting head with an off-axis supersonic nozzle was developed. Furthermore, a comparison between the utilization of a conventional coaxial conical nozzle to inject the assist gas and the new system is presented. The results obtained give clear proof that the use of the new gas injection system leads to a great improvement on the cut quality by means of a more efficient removing of the molten material out of the cutting front. This result is of special interest in the laser fusion cutting of thick ceramic plates at high processing rates

Absorption of nitric oxide from simulated flue gas using different absorbents at room temperature and atmospheric pressure

International Nuclear Information System (INIS)

Yu, Hesheng; Zhu, Qunyi; Tan, Zhongchao

2012-01-01

Effective removal of nitrogen oxides (NO x ) from flue gas allows more fossil fuels to be produced and utilized with less negative impact on the environment. It would be more cost-effective, however, if nitric oxide (NO) is oxidized to soluble nitrate and nitrite and then removed from the air by existing desulfurization wet scrubbers. This paper compares the effectiveness of three different oxidants for this purpose, namely, ethylenediaminetetraacetic acid; iron (2+) (Fe(II)–EDTA), hexamminecobalt(II) chloride ([Co(NH 3 ) 6 ]Cl 2 ), and hydrogen peroxide (H 2 O 2 ). Experimental results using column reactors showed that [Co(NH 3 ) 6 ]Cl 2 was more effective over the same period of time. The best initial NO removal efficiency of about 96.45% was measured at the inlet flow rate of 500 ml/min; the temperature of approximately 19 °C; the pH value of around 10.5; and the concentrations of [Co(NH 3 ) 6 ]Cl 2 , NO and O 2 of 0.06 mol/L, 500 ppm and 5.0%, respectively.

Development of selective catalytic oxidation (SCO) for NH{sub 3} and HCN removal from gasification gas; Selektiivisen katalyyttisen hapetusprosessin (SCO) kehittaeminen kaasutuskaasun NH{sub 3}:n ja HCN:n poistoon

Energy Technology Data Exchange (ETDEWEB)

Leppaelahti, J.; Koljonen, T.; Heiskanen, K. [VTT Energy, Espoo (Finland)

1997-10-01

In gasification, reactive nitrogen compounds (mainly NH{sub 3} and HCN) are formed from fuel nitrogen. If the gas containing NH{sub 3} is burned, a high NO{sub x} emission may be formed. The content of nitrogen compounds of the hot gasification gas could be reduced in Selective Catalytic Oxidation (SCO) process. In this process small amounts of reactive oxidisers are injected into the gas in order to convert NH{sub 3} to N{sub 2}. The utilization of SCO process together with low NO{sub x} burners in advanced gasification power stations might offer an alternative for flue gas treatment technologies like SCR (Selective Catalytic Reduction). In the earlier research, conditions were found, where oxidizers reacted selectively with ammonia in the gasification gas. Highest ammonia reduction took place in the aluminium oxide bed in the presence of NO and O{sub 2}. The aim of this study is to examine the reaction mechanism in order to be able to further evaluate the development possibilities of this kind process. The effect of composition and the amount of added oxidizer, the content of combustible gas components, space velocity, pressure and temperature will be studied. The experiments are carried out with the laboratory scale high pressure flow reactor of VTT Energy. Kinetic modelling of the experimental results is carried out in co-operation with the combustion chemistry group of Aabo Akademi. The aim of the modelling work is to bring insight to the gas-phase reactions that are important for the SCO-process. (orig.)

Understanding the petroleum and natural gas regime in Saskatchewan

International Nuclear Information System (INIS)

Lothian, E.C.

1997-01-01

Some of the legal issues relating to exploring for and operating oil and gas properties in Saskatchewan were discussed. An overview of key legislation was provided. The purpose of the Oil and Gas Conservation Act (OGCA) was explained, i.e., (1) to prevent waste, (2) to regulate all oil and gas operations to maximize ultimate recovery through prudent operations, (3) to allow each owner the opportunity to recover its share of oil or gas from a pool, (4) to develop, protect and conserve Saskatchewan's oil and gas resources, and (5) to protect the environment from the harmful effects of oil and gas operations. Legislation regarding vertical wells, horizontal wells, and horizontal well spacing was reviewed. Similar explanations were provided for the key features of the Petroleum and Natural Gas Regulations, the Freehold Oil and Gas Production Tax Act, the Mineral Taxation Act, the Land Titles Act, and the Builder's Lien Act. Registration issues for Crown and freehold lands, and non-contractual operator's duties were also reviewed. A brief reference was also made to a recent report entitled the 'Saskatchewan External Cost Review' which indicated that Saskatchewan had certain advantages for producing oil and gas compared to Alberta, Manitoba, British Columbia and North Dakota. Unfortunately, the report also indicated that the external costs ( crown royalties, freehold production taxes, income taxes, sales taxes, etc.), were the highest in Saskatchewan of the four jurisdictions reviewed

Laboratory Connections--Gas Monitoring Transducers Part III: Combustible Gas Sensors.

Science.gov (United States)

Powers, Michael H.; Dahman, Doug

1989-01-01

Describes an interface that uses semiconductor metal oxides to detect low gas concentrations. Notes the detector has long life, high stability, good reproducibility, low cost, and is able to convert the gas concentration to an electrical signal with a simple circuit. Theory, schematic, and applications are provided. (MVL)

Regenerable cobalt oxide loaded magnetosphere catalyst from fly ash for mercury removal in coal combustion flue gas.

Science.gov (United States)

Yang, Jianping; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

2014-12-16

To remove Hg(0) in coal combustion flue gas and eliminate secondary mercury pollution of the spent catalyst, a new regenerable magnetic catalyst based on cobalt oxide loaded magnetospheres from fly ash (Co-MF) was developed. The catalyst, with an optimal loading of 5.8% cobalt species, attained approximately 95% Hg(0) removal efficiency at 150 °C under simulated flue gas atmosphere. O2 could enhance the Hg(0) removal activity of magnetospheres catalyst via the Mars-Maessen mechanism. SO2 displayed an inhibitive effect on Hg(0) removal capacity. NO with lower concentration could promote the Hg(0) removal efficiency. However, when increasing the NO concentration to 300 ppm, a slightly inhibitive effect of NO was observed. In the presence of 10 ppm of HCl, greater than 95.5% Hg(0) removal efficiency was attained, which was attributed to the formation of active chlorine species on the surface. H2O presented a seriously inhibitive effect on Hg(0) removal efficiency. Repeated oxidation-regeneration cycles demonstrated that the spent Co-MF catalyst could be regenerated effectively via thermally treated at 400 °C for 2 h.

Ethylene oxide gas sterilization does not reduce the osteoinductive potential of demineralized bone in rats

DEFF Research Database (Denmark)

Solheim, E; Pinholt, E M; Bang, G

1995-01-01

It has been shown that different sterilization procedures of demineralized bone may influence its osteoinductive properties. The aim of this study was to evaluate the effect of ethylene oxide sterilization for 1, 3, and 6 hours on the osteoinductive potential of allogeneic demineralized bone...... implanted heterotopically in rats. Sixty male Wistar rats were randomly assigned to one of four groups, A through D, and four demineralized bone chips (2.8 mg) were implanted in a pouch created between the right oblique abdominal muscles in each animal. In Group A, the demineralized bone was implanted...... without prior sterilization of the material, whereas the demineralized bone implanted in Groups B, C, and D had been sterilized in ethylene oxide gas for 1, 3, or 6 hours, respectively, and aerated for 48 hours. At 4 weeks postoperatively, bone formation was evaluated quantitatively by strontium 85 uptake...

Effect of cathode gas humidification on performance and durability of Solid Oxide Fuel Cells

DEFF Research Database (Denmark)

Nielsen, Jimmi; Hagen, Anke; Liu, Yi-Lin

2010-01-01

The effect of cathode inlet gas humidification was studied on single anode supported Solid Oxide Fuel Cells (SOFC's). The studied cells were Risø 2 G and 2.5 G. The former consists of a LSM:YSZ composite cathode, while the latter consists of a LSCF:CGO composite cathode on a CGO protection layer....... The humidification effect was found to be dependent on both the degree of humidification and the cathode polarization. No significant effect of humidification was found at OCV which rules out the possibility of a traditional poisoning effect with a blocking of active sites. Post-mortem high resolution FEG......-SEM analysis showed clear changes at and around the cathode/electrolyte contact area. In contrast to Risø 2 G cells, a very high tolerance towards humidification of cathode gas air was observed for Risø 2.5 G cells with no detectable effect of humidification even when the humidification was as high as 12.8 mol%...

UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides

Directory of Open Access Journals (Sweden)

Kuang-Hung Tseng

2014-06-01

Full Text Available The purpose of this study was to investigate the difference between tungsten inert gas (TIG welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO2 leads to a satisfactory surface appearance compared to that of the TIG weld made with Al2O3. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO2, the TIG welding with nanoparticle SiO2 has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al2O3 does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO2 uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al2O3 results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

Tritium oxidation and exchange: preliminary studies

International Nuclear Information System (INIS)

Phillips, J.E.; Easterly, C.E.

1978-05-01

The radiological hazard resulting from an exposure to either tritium oxide or tritium gas is discussed and the factors contributing to the hazard are presented. From the discussion it appears that an exposure to tritium oxide vapor is 10 4 to 10 5 times more hazardous than exposure to tritium gas. Present and future sources of tritium are briefly considered and indicate that most of the tritium has been and is being released as tritium oxide. The likelihood of gaseous releases, however, is expected to increase in the future, calling to task the present general release assumption that 100% of all tritium released is as oxide. Accurate evaluation of the hazards from a gaseous release will require a knowledge of the conversion rate of tritium gas to tritium oxide. An experiment for determining the conversion rate of tritium gas to tritium oxide is presented along with some preliminary data. The conversion rates obtained for low initial concentrations (10 -4 to 10 -1 mCi/ml) indicate the conversion may proceed more rapidly than would be expected from an extrapolation of previous data taken at higher concentrations

Methane oxidation and formation of EPS in compost: effect of oxygen concentration

International Nuclear Information System (INIS)

Wilshusen, J.H.; Hettiaratchi, J.P.A.; Visscher, A. de; Saint-Fort, R.

2004-01-01

Oxygen concentration plays an important role in the regulation of methane oxidation and the microbial ecology of methanotrophs. However, this effect is still poorly quantified in soil and compost ecosystems. The effect of oxygen on the formation of exopolymeric substances (EPS) is as yet unknown. We studied the effect of oxygen on the evolution of methanotrophic activity. At both high and low oxygen concentrations, peak activity was observed twice within a period of 6 months. Phospholipid fatty acid analysis showed that there was a shift from type I to type II methanotrophs during this period. At high oxygen concentration, EPS production was about 250% of the amount at low oxygen concentration. It is hypothesized that EPS serves as a carbon cycling mechanism for type I methanotrophs when inorganic nitrogen is limiting. Simultaneously, EPS stimulates nitrogenase activity in type II methanotrophs by creating oxygen-depleted zones. The kinetic results were incorporated in a simulation model for gas transport and methane oxidation in a passively aerated biofilter. Comparison between the model and experimental data showed that, besides acting as a micro-scale diffusion barrier, EPS can act as a barrier to macro-scale diffusion, reducing the performance of such biofilters. - 1.5% oxygen resulted in a slightly higher and more stable methane oxidation activity

Method for the removal of elemental mercury from a gas stream

Science.gov (United States)

Mendelsohn, Marshall H.; Huang, Hann-Sheng

1999-01-01

A method is provided to remove elemental mercury from a gas stream by reacting the gas stream with an oxidizing solution to convert the elemental mercury to soluble mercury compounds. Other constituents are also oxidized. The gas stream is then passed through a wet scrubber to remove the mercuric compounds and oxidized constituents.

Fast response of carbon monoxide gas sensors using a highly porous network of ZnO nanoparticles decorated on 3D reduced graphene oxide

Science.gov (United States)

Ha, Nguyen Hai; Thinh, Dao Duc; Huong, Nguyen Thanh; Phuong, Nguyen Huy; Thach, Phan Duy; Hong, Hoang Si

2018-03-01

Zinc oxide (ZnO) nanoparticles loaded onto 3D reduced graphene oxide (3D-RGO) for carbon monoxide (CO) sensing were synthesized using hydrothermal method. The highly porous ZnO/3D-RGO configuration was stable without collapsing and was deposited on the micro-heater of the CO gas sensor. The resulting CO gas sensor displayed high sensitivity, fast response/recovery, and good linearity. The sensor achieved a response value of 85.2% for 1000 ppm CO at a working temperature of 200 °C. The response and recovery times of the sensor were 7 and 9 s for 1000 ppm CO at 200 °C. Similarly, the response value, response time, and recovery time of the sensor at room temperature were 27.5%, 14 s, and 15 s, respectively. The sensor demonstrated a distinct response to various CO concentrations in the range of 1-1000 ppm and good selectivity toward CO gas. In addition, the sensor exhibited good repeatability in multi-cycle and long-term stability.

Comparing the effects of cryotherapy with nitrous oxide gas versus topical corticosteroids in the treatment of oral lichen planus

Directory of Open Access Journals (Sweden)

Dariush Amanat

2014-01-01

Conclusion: Cryotherapy with nitrous oxide gas is as effective as topical triamcinolone acetonide in the treatment of OLP with no systemic side effects and needs less patient compliance. It can be considered as an alternative or adjuvant therapy in OLP patients to reduce the use of treatments with adverse effects.

Thermodynamic analysis of solid oxide fuel cell gas turbine systems operating with various biofuels

Energy Technology Data Exchange (ETDEWEB)

Patel, H.C.; Woudstra, T.; Aravind, P.V. [Process and Energy Laboratory, Delft University of Technology, Section Energy Technology, Leeghwaterstraat 44, 2628 CA Delft (Netherlands)

2012-12-15

Solid oxide fuel cell-gas turbine (SOFC-GT) systems provide a thermodynamically high efficiency alternative for power generation from biofuels. In this study biofuels namely methane, ethanol, methanol, hydrogen, and ammonia are evaluated exergetically with respect to their performance at system level and in system components like heat exchangers, fuel cell, gas turbine, combustor, compressor, and the stack. Further, the fuel cell losses are investigated in detail with respect to their dependence on operating parameters such as fuel utilization, Nernst voltage, etc. as well as fuel specific parameters like heat effects. It is found that the heat effects play a major role in setting up the flows in the system and hence, power levels attained in individual components. The per pass fuel utilization dictates the efficiency of the fuel cell itself, but the system efficiency is not entirely dependent on fuel cell efficiency alone, but depends on the split between the fuel cell and gas turbine powers which in turn depends highly on the nature of the fuel and its chemistry. Counter intuitively it is found that with recycle, the fuel cell efficiency of methane is less than that of hydrogen but the system efficiency of methane is higher. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

High temperature oxidation behaviour of nanostructured cermet coatings in amixed CO/sub 2/ - O/sub 2/ environment

International Nuclear Information System (INIS)

Farrokhzad, M. A.; Khan, T. I.

2013-01-01

Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (alpha-Al /sub 2/O/sub 3/ and TiO/sub 2/) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500 degree C, 600 degree C and 700 degree C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15 percentage CO/sub 2/, 10 percentage O/sub 2/ and 75 percentage N/sub 2/. This research investigates the effects of CO/sub 2/ and O/sub 2/ partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO/sub 2/ at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO/sub 2/ in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO/sub 2/ acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO/sub 2/ particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Nu i-Tau i compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings. (author)

The enhancement of CuO modified V2O5-WO3/TiO2 based SCR catalyst for Hg° oxidation in simulated flue gas

Science.gov (United States)

Chen, Chuanmin; Jia, Wenbo; Liu, Songtao; Cao, Yue

2018-04-01

CuO modified V2O5-WO3/TiO2 based SCR catalysts prepared by improved impregnation method were investigated to evaluate the catalytic activity for elemental mercury (Hg°) oxidation in simulated flue gas at 150-400 °C. Nitrogen adsorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. It was found that V0.8WTi-Cu3 catalyst exhibited the superior Hg° oxidation activity and wide operating temperature window at the gas hourly space velocity (GHSV) of 3 × 105 h-1. The BET and XRD results showed that CuO was well loaded and highly dispersed on the catalysts surface. The XPS results suggested that the addition of CuO generated abundant chemisorbed oxygen, which was due to the synergistic effect between CuO and V2O5. The existence of the redox cycle of V4+ + Cu2+ ↔ V5+ + Cu+ in V0.8WTi-Cu3 catalyst enhanced Hg° oxidation activity. The effects of flue gas components (O2, NO, SO2 and H2O) on Hg° oxidation over V0.8WTi-Cu3 catalyst were also explored. Moreover, the co-presence of NO and NH3 remarkably inhibited Hg° oxidation, which was due to the competitive adsorption and reduction effect of NH3 at SCR condition. Fortunately, this inhibiting effect was gradually scavenged with the decrease of GHSV. The mechanism of Hg° oxidation was also investigated.

18 CFR 157.212 - Synthetic and liquefied natural gas facilities.

Science.gov (United States)

2010-04-01

... natural gas facilities. 157.212 Section 157.212 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER NATURAL GAS ACT APPLICATIONS FOR CERTIFICATES... 7 OF THE NATURAL GAS ACT Interstate Pipeline Blanket Certificates and Authorization Under Section 7...

Method for the removal of elemental mercury from a gas stream

Science.gov (United States)

Mendelsohn, M.H.; Huang, H.S.

1999-05-04

A method is provided to remove elemental mercury from a gas stream by reacting the gas stream with an oxidizing solution to convert the elemental mercury to soluble mercury compounds. Other constituents are also oxidized. The gas stream is then passed through a wet scrubber to remove the mercuric compounds and oxidized constituents. 7 figs.

Effects of H2/O2 mixed gas plasma treatment on electrical and optical property of indium tin oxide

International Nuclear Information System (INIS)

Kim, Jun Young; Lee, Dong-Min; Kim, Jae-Kwan; Yang, Su-Hwan; Lee, Ji-Myon

2013-01-01

Highlights: ► The specific resistivity of ITO was enhanced by H 2 + O 2 mixed gas plasma treatment. ► The transmittance was same as that of untreated ITO after plasma treatment. ► The process was carried out at room temperature without any step of post-treatment. - Abstract: This study examined the effects of H 2 and H 2 + O 2 mixed gas plasma treatment on the properties of ITO films. The films were deposited on corning glass by RF magnetron sputtering under Ar and Ar/O 2 mixed gas ambient. After a H 2 plasma treatment, the ITO films showed an improved specific resistance due to the formation of oxygen vacancies acting as shallow donors, but showed quenched transmittance due to the formation of agglomerated metals on the surface. After an H 2 + O 2 mixed gas plasma treatment, the specific resistance of the film was improved without deteriorating transmittance. The enhanced specific resistance by mixed gas plasma treatment was attributed to the formation of free electrons by the incorporation of H in the lattice.

Non-CO2 greenhouse gas emissions associated with food production: methane (CH4) and nitrous oxide (N2O)

International Nuclear Information System (INIS)

Carlsson-Kanyama, Annika

2007-01-01

It is well known that the agriculture and livestock sectors are large contributors of N 2 O and CH 4 emissions in countries with agricultural activities and that remedial measures are needed in these sectors in order to curb contributions to global warming. This study examines non- CO 2 greenhouse gas emissions associated with the production of food. Methane (CH 4 ) and nitrous oxide (N 2 O) are the most relevant greenhouse gases in this category, and they are emitted mainly in the agricultural sector. These greenhouse gases have a Global Warming Potential much higher than CO 2 itself (25- and 298-fold higher, respectively, in a 100-year perspective). Emission intensities and the corresponding uncertainties were calculated based on the latest procedures and data published by the Intergovernmental Panel on Climate Change and used to facilitate calculations comparing greenhouse gas emissions for food products and diets. When the proposed emission intensities were applied to agricultural production, the results showed products of animal origin and the cultivation of rice under water to have high emissions compared with products of vegetable origin cultivated on upland soils, such as wheat and beans. In animal production the main source of greenhouse gas emissions was methane from enteric fermentation, while emissions of nitrous oxides from fertilisers were the main sources of greenhouse gas emissions for cereal and legume cultivation. For rice cultivation, methane emissions from flooded rice fields contributed most. Other significant sources of greenhouse gas emissions during animal production were manure storage and management. We suggest that the proposed emission factors, together with the associated uncertainties, can be a tool for better understanding the potential to mitigate emissions of greenhouse gases through changes in the diet

Removal of 14C from nitrogen annulus gas

International Nuclear Information System (INIS)

Cheh, C.H.

1985-01-01

A dry, ambient temperature process using Ca(OH) 2 as the sorbent to remove 14 CO 2 from moderator cover gas was further developed to remove 14 C from the extremely dry nitrogen annulus gas. Thermal gravimetric analysis was carried out to study the thermal stability of Ca(OH) 2 and the CO 2 -Ca(OH) 2 reaction at elevated temperatures under extremely low humidity conditions. Results shows that to achieve high utilization and avoid decomposition of Ca(OH) 2 , humidification of the annulus gas was necessary at high or low temperatures. Results of the bench scale (1-10 L/min) oxidizer study showed that, with 0.5% Pd or alumina as the catalyst, it was possible to achieve complete oxidation of CO and over 80% oxidation of CH 4 with 1% hydrogen in the nitrogen. The gas superficial velocity should be less than or equal to30 cm/s and the residence time greater than or equal to0.5 s. A pilot scale (up to 160 L/min) system including a catalytic oxidizer, a humidifier/demister, a Ca(OH) 2 reactor, a condenser/demister and regenerable molecular sieve dryers, was assembled and tested with simulated nitrogen annulus gas. Results showed that complete oxidation of the CO and 60-100% oxidation of the CH 4 with 0.5% H 2 in the simulated gas were achieved in the pilot plant. The CO 2 concentration was reduced from 30-60 μL/L at the inlet of the Ca(OH) 2 reactor to 1 μL/L or less at the outlet. After modifications of the dryer to overcome the problems encountered, the simulated annulus gas was dried to 0 C dew point before recirculation. Equipment specifications and operating conditions of a 14 C removal system for nitrogen annulus gas are summarized

Shrinkage Effects of the Conduction Zone in the Electrical Properties of Metal Oxide Nanocrystals: The Basis for Room Temperature Conductometric Gas Sensor

Directory of Open Access Journals (Sweden)

M. Manzanares

2009-01-01

Full Text Available The influence of charge localized at the surface of minute metal oxide nanocrystals was studied in WO3 and In2O3 nanostructures, which were obtained replicating mesoporous silica templates. Here, it is shown that the very high resistive states observed at room temperature and dark conditions were originated by the total shrinkage of the conductive zone in the inner part of these nanocrystals. On the contrary, at room temperature and under UV illumination, both photogenerated electron-hole pairs and empty surface states generated by photons diminished the negative charge accumulated at the surface, enlarging the conductive zone and, as a consequence, leading to a reduction of the electrical resistance. Under these conditions, empty surface states produced by UV light reacted with oxidizing gaseous molecules. The charge exchange associated to these reactions also affected the size of the inner conductive zone, and leaded to a new steady-state resistance. These chemical, physical and geometrical effects can be used for gas detection, and constitutes the basis for developing novel room temperature conductometric gas sensors responsive to oxidizing species.

Effect of PEEP and inhaled nitric oxide on pulmonary gas exchange during gaseous and partial liquid ventilation with small volumes of perfluorocarbon.

Science.gov (United States)

Max, M; Kuhlen, R; Falter, F; Reyle-Hahn, M; Dembinski, R; Rossaint, R

2000-04-01

Partial liquid ventilation, positive end-expiratory pressure (PEEP) and inhaled nitric oxide (NO) can improve ventilation/perfusion mismatch in acute lung injury (ALI). The aim of the present study was to compare gas exchange and hemodynamics in experimental ALI during gaseous and partial liquid ventilation at two different levels of PEEP, with and without the inhalation of nitric oxide. Seven pigs (24+/-2 kg BW) were surfactant-depleted by repeated lung lavage with saline. Gas exchange and hemodynamic parameters were assessed in all animals during gaseous and subsequent partial liquid ventilation at two levels of PEEP (5 and 15 cmH2O) and intermittent inhalation of 10 ppm NO. Arterial oxygenation increased significantly with a simultaneous decrease in cardiac output when PEEP 15 cmH2O was applied during gaseous and partial liquid ventilation. All other hemodynamic parameters revealed no relevant changes. Inhalation of NO and instillation of perfluorocarbon had no additive effects on pulmonary gas exchange when compared to PEEP 15 cmH2O alone. In experimental lung injury, improvements in gas exchange are most distinct during mechanical ventilation with PEEP 15 cmH2O without significantly impairing hemodynamics. Partial liquid ventilation and inhaled NO did not cause an additive increase of PaO2.

Cu-modified carbon spheres/reduced graphene oxide as a high sensitivity of gas sensor for NO2 detection at room temperature

Science.gov (United States)

Su, Zhibin; Tan, Li; Yang, Ruiqiang; Zhang, Yu; Tao, Jin; Zhang, Nan; Wen, Fusheng

2018-03-01

Nitrogen dioxide (NO2) as one of the most serious air pollution is harmful to people's health, therefore high-performance gas sensors is critically needed. Here, Cu-modified carbon spheres/reduced graphene oxide (Cu@CS/RGO) composite have been prepared as NO2 gas sensor material. Carbon sphere in the interlayer of RGO can increase the specific surface area of RGO. Copper nanoparticles decorated on the surface of CS can effectively enhance the adsorption activity of RGO as supplier of free electrons. The experimental results showed that its particular structure improved the gas sensitivity of RGO at different NO2 concentrations at room temperature.

Effects of gas flow rate on the structure and elemental composition of tin oxide thin films deposited by RF sputtering

Science.gov (United States)

Al-Mansoori, Muntaser; Al-Shaibani, Sahar; Al-Jaeedi, Ahlam; Lee, Jisung; Choi, Daniel; Hasoon, Falah S.

2017-12-01

Photovoltaic technology is one of the key answers for a better sustainable future. An important layer in the structure of common photovoltaic cells is the transparent conductive oxide. A widely applied transparent conductive oxide is tin oxide (SnO2). The advantage of using tin oxide comes from its high stability and low cost in processing. In our study, we investigate effects of working gas flow rate and oxygen content in radio frequency (RF)-sputtering system on the growth of intrinsic SnO2 (i-SnO2) layers. X-ray diffraction results showed that amorphous-like with nano-crystallite structure, and the surface roughness varied from 1.715 to 3.936 nm. X-Ray photoelectron spectroscopy analysis showed different types of point defects, such as tin interstitials and oxygen vacancies, in deposited i-SnO2 films.

Effects of gas flow rate on the structure and elemental composition of tin oxide thin films deposited by RF sputtering

Directory of Open Access Journals (Sweden)

Muntaser Al-Mansoori

2017-12-01

Full Text Available Photovoltaic technology is one of the key answers for a better sustainable future. An important layer in the structure of common photovoltaic cells is the transparent conductive oxide. A widely applied transparent conductive oxide is tin oxide (SnO2. The advantage of using tin oxide comes from its high stability and low cost in processing. In our study, we investigate effects of working gas flow rate and oxygen content in radio frequency (RF-sputtering system on the growth of intrinsic SnO2 (i-SnO2 layers. X-ray diffraction results showed that amorphous-like with nano-crystallite structure, and the surface roughness varied from 1.715 to 3.936 nm. X-Ray photoelectron spectroscopy analysis showed different types of point defects, such as tin interstitials and oxygen vacancies, in deposited i-SnO2 films.

Exhaust gas treatment by electron beam irradiation

International Nuclear Information System (INIS)

Shibamura, Yokichi; Suda, Shoichi; Kobayashi, Toshiki

1991-01-01

Among global environmental problems, atmospheric pollution has been discussed since relatively old days, and various countermeasures have been taken, but recently in connection with acid rain, the efficient and economical treatment technology is demanded. As the denitration and desulfurization technology for the exhaust gas from the combustion of fossil fuel, the incineration of city trash and internal combustion engines, three is the treatment method by electron beam irradiation. By irradiating electron beam to exhaust gas, nitrogen oxides and sulfur oxides are oxidized to nitric acid and sulfuric acid, and by promoting the neutralization of these acids with injected alkali, harmless salts are recovered. This method has the merit that nitrogen oxides and surfur oxides can be removed efficiently with a single system. In this report, as for the exhaust gas treatment by electron beam irradiation, its principle, features, and the present status of research and development are described, and in particular, the research on the recent exhaust gas treatment in city trash incineration is introduced. This treatment method is a dry process, accordingly, waste water disposal is unnecessary. The reaction products are utilized as fertilizer, and waste is not produced. (K.I.)

Sn and Cu oxide nanoparticles deposited on TiO{sub 2} nanoflower 3D substrates by Inert Gas Condensation technique

Energy Technology Data Exchange (ETDEWEB)

Kusior, A., E-mail: akusior@agh.edu.pl [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Kollbek, K. [Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Kowalski, K. [Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Borysiewicz, M. [Institute of Electron Technology, al. Lotnikow 32/46, 02-668 Warszawa (Poland); Wojciechowski, T. [Institute of Physics Polish Academy of Science, al. Lotnikow 32/46, 02-668 Warszawa (Poland); Adamczyk, A.; Trenczek-Zajac, A.; Radecka, M. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Zakrzewska, K. [Faculty of Computer Science, Electronics and Telecommunications, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland)

2016-09-01

Graphical abstract: - Highlights: • Inert Gas Condensation method yields non-agglomerated nanoparticles. • The growth of nanoparticles is controllable at the level of deposition. • Electrical conductivity increases with respect to pure nanostructured TiO{sub 2}. - Abstract: Sn and Cu oxide nanoparticles were deposited by Inert Gas Condensation (IGC) technique combined with dc magnetron sputtering onto nanoflower TiO{sub 2} 3D substrates obtained in the oxidation process of Ti-foil in 30% H{sub 2}O{sub 2}. Sputtering parameters such as insertion length and Ar/He flow rates were optimized taking into account the nanostructure morphology. Comparative studies with hydrothermal method were carried out. Surface properties of the synthesized nanomaterials were studied by Scanning Electron Microscopy, SEM, Atomic Force Microscopy, AFM, and X-ray Photoelectron Spectroscopy, XPS. X-ray diffraction, XRD and Raman spectroscopy were performed in order to determine phase composition. Impedance spectroscopy demonstrated the influence of nanoparticles on the electrical conductivity.

Visualization of Gas Distribution in a Model AP-XPS Reactor by PLIF: CO Oxidation over a Pd(100 Catalyst

Directory of Open Access Journals (Sweden)

Jianfeng Zhou

2017-01-01

Full Text Available In situ knowledge of the gas phase around a catalyst is essential to make an accurate correlation between the catalytic activity and surface structure in operando studies. Although ambient pressure X-ray photoelectron spectroscopy (AP-XPS can provide information on the gas phase as well as the surface structure of a working catalyst, the gas phase detected has not been spatially resolved to date, thus possibly making it ambiguous to interpret the AP-XPS spectra. In this work, planar laser-induced fluorescence (PLIF is used to visualize the CO2 distribution in a model AP-XPS reactor, during CO oxidation over a Pd(100 catalyst. The results show that the gas composition in the vicinity of the sample measured by PLIF is significantly different from that measured by a conventional mass spectrometer connected to a nozzle positioned just above the sample. In addition, the gas distribution above the catalytic sample has a strong dependence on the gas flow and total chamber pressure. The technique presented has the potential to increase our knowledge of the gas phase in AP-XPS, as well as to optimize the design and operating conditions of in situ AP-XPS reactors for catalysis studies.

Influence of Gas Atmosphere Dew Point on the Selective Oxidation and the Reactive Wetting During Hot Dip Galvanizing of CMnSi TRIP Steel

Science.gov (United States)

Cho, Lawrence; Lee, Seok Jae; Kim, Myung Soo; Kim, Young Ha; De Cooman, Bruno C.

2013-01-01

The selective oxidation and reactive wetting of intercritically annealed Si-bearing CMnSi transformation-induced plasticity steels were investigated by high-resolution transmission electron microscopy. In a N2 + 10 pct H2 gas atmosphere with a dew point (DP) ranging from 213 K to 278 K (-60 °C to 5 °C), a continuous layer of selective oxides was formed on the surface. Annealing in a higher DP gas atmosphere resulted in a thinner layer of external oxidation and a greater depth of internal oxidation. The hot dipping was carried out in a Zn bath containing 0.22 mass pct Al, and the bath temperature was 733 K (460 °C). Coarse and discontinuous Fe2Al5- x Zn x grains and Fe-Zn intermetallics (ζ and δ) were observed at the steel/coating interface after the hot dip galvanizing (HDG) of panels were annealed in a low DP atmosphere 213 K (-60 °C). The Fe-Zn intermetallics were formed both in areas where the Fe2Al5- x Zn x inhibition layer had not been formed and on top of non-stoichiometric Fe-Al-Zn crystals. Poor wetting was observed on panels annealed in a low DP atmosphere because of the formation of thick film-type oxides on the surface. After annealing in higher DP gas atmospheres, i.e., 263 K and 278 K (-10 °C and 5 °C), a continuous and fine-grained Fe2Al5- x Zn x layer was formed. No Fe-Zn intermetallics were formed. The small grain size of the inhibition layer was attributed to the nucleation of the Fe2Al5- x Zn x grains on small ferrite sub-surface grains and the presence of granular surface oxides. A high DP atmosphere can therefore significantly contribute to the decrease of Zn-coating defects on CMnSi TRIP steels processed in HDG lines.

Greenhouse gas emission and exergy analyses of an integrated trigeneration system driven by a solid oxide fuel cell

International Nuclear Information System (INIS)

Chitsaz, Ata; Mahmoudi, S. Mohammad S.; Rosen, Marc A.

2015-01-01

Exergy and greenhouse gas emission analyses are performed for a novel trigeneration system driven by a solid oxide fuel cell (SOFC). The trigeneration system also consists of a generator-absorber heat exchanger (GAX) absorption refrigeration system and a heat exchanger to produce electrical energy, cooling and heating, respectively. Four operating cases are considered: electrical power generation, electrical power and cooling cogeneration, electrical power and heating cogeneration, and trigeneration. Attention is paid to numerous system and environmental performance parameters, namely, exergy efficiency, exergy destruction rate, and greenhouse gas emissions. A maximum enhancement of 46% is achieved in the exergy efficiency when the SOFC is used as the primary mover for the trigeneration system compared to the case when the SOFC is used as a standalone unit. The main sources of irreversibility are observed to be the air heat exchanger, the SOFC and the afterburner. The unit CO 2 emission (in kg/MWh) is considerably higher for the case in which only electrical power is generated. This parameter is reduced by half when the system is operates in a trigeneration mode. - Highlights: • A novel trigeneration system driven by a solid oxide fuel cell is analyzed. • Exergy and greenhouse gas emission analyses are performed. • Four special cases are considered. • An enhancement of up to 46% is achieved in exergy efficiency. • The CO 2 emission drops to a relatively low value for the tri-generation case

The Energy Policy Act of 1992 and reductions in greenhouse gas emissions: The petroleum industry perspective

International Nuclear Information System (INIS)

Baer, M.T.

1994-01-01

The Energy Policy Act of 1992 (EPAct) directs the US Department of Energy policies, programs and regulations to stabilize and reduce the quantities of greenhouse gas emissions. These objectives will be accomplished through the regulation of sources associated with the production, transportation/distribution, and end-use of energy resources. Almost all of the 30 titles of the Act affect these sources: from the energy efficiency provisions of Titles 1 and XXI to the alternative fuels and vehicles programs of Titles 3 through 5; from the global climate change requirements of Title XVI to the petroleum alternative research programs of Titles VI, XII, XIII, XX, and XXI; and from the multiple titles pertaining to the development and regulation of nuclear facilities, supplies, and waste. The goals of the law are to: (1) reduce the use of oil in the domestic energy mix from 40% in 1990 to 35% by the year 2005, (2) require the use of alternative fuels and alternative fuel vehicles in designated fleets, (3) replace up to 30% of motor fuels with ''replacement fuels'' by the year 2010, (4) increase the overall efficiency of consumer, residential, and commercial products, (5) reduce and stabilize the emissions of greenhouse gases, and (6) encourage the development and commercialization of renewable and non petroleum energy resources. All these goals are intended to reduce the emissions of greenhouse gases as well. The EPAct's potential to impact all forms of energy and all energy producers and suppliers is obvious and substantial. This paper assesses three goals of the EPAct, now under study by the petroleum industry, that will affect the production, supply, composition, and use of petroleum products, most notably gasoline and natural gas

Valve for gas centrifuges

Science.gov (United States)

Hahs, Charles A.; Burbage, Charles H.

1984-01-01

The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

Impact of pH on hydrogen oxidizing redox processes in aquifers due to gas intrusions

Science.gov (United States)

Metzgen, Adrian; Berta, Marton; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

2017-04-01

Hydrogen production from excess energy and its storage can help increasing the efficiency of solar and wind in the energy mix. Therefore, hydrogen needs large-scale intermediate storage independent of the intended later use as hydrogen gas or as reactant to produce methane in the Sabatier process. A possible storage solution is using the geological subsurface such as caverns built in salt deposits or aquifers that are not used for drinking water production. However, underground storage of hydrogen gas potentially leads to accidental gas leakages into near-surface potable aquifers triggering subsequent geochemical processes. These leakages pose potential risks that are currently not sufficiently understood. To close this gap in knowledge, a high-pressure laboratory column system was used to simulate a hydrogen gas intrusion into a shallow aquifer. Water and sediment were gained from a sandy Pleistocene aquifer near Neumünster, Germany. In the first stage of the experiment, 100% hydrogen gas was used to simulate dissolved hydrogen concentrations between 800 and 4000 µM by varying pH2 between 2 and 15 bars. pH values rose to between 7.9 and 10.4, partly due to stripping CO2 from the groundwater used during H2 gas addition. In a second stage, the pH was regulated in a range of 6.7 to 7.9 by using a gas mixture of 99% H2 and 1% CO2 at 5 bars of total gas pressure. Observed processes included hydrogen oxidation, sulfate reduction, acetogenesis, formate production, and methanogenesis, which were independent of the hydrogen concentration. Hydrogen oxidation and sulfate reduction showed zeroth order reaction rates and rate constants (106 to 412 µM/h and 12 to 33 µM/h, respectively) in the pH range between 8 and 10. At pH levels between 7 and 8, both reactions started out faster near the column's inflow but then seemed limited towards the columns outflow, suggesting the dependence of sulfate reduction on the pH-value. Acetogenesis dominated the pH range between 8 and 10

Metal oxide gas sensors on the nanoscale

Science.gov (United States)

Plecenik, A.; Haidry, A. A.; Plecenik, T.; Durina, P.; Truchly, M.; Mosko, M.; Grancic, B.; Gregor, M.; Roch, T.; Satrapinskyy, L.; Moskova, A.; Mikula, M.; Kus, P.

2014-06-01

Low cost, low power and highly sensitive gas sensors operating at room temperature are very important devices for controlled hydrogen gas production and storage. One of the disadvantages of chemosensors is their high operating temperature (usually 200 - 400 °C), which excludes such type of sensors from usage in explosive environment. In this report, a new concept of gas chemosensors operating at room temperature based on TiO2 thin films is discussed. Integration of such sensor is fully compatible with sub-100 nm semiconductor technology and could be transferred directly from labor to commercial sphere.

[Efficiency of oxidant gas generator cells powered by electric or solar energy].

Science.gov (United States)

Brust Carmona, H; Benitez, A; Zarco, J; Sánchez, E; Mascher, I

1998-02-01

Diseases caused by microbial contaminants in drinking water continue to be a serious problem in countries like Mexico. Chlorination, using chlorine gas or chlorine compounds, is one of the best ways to treat drinking water. However, difficulties in handling chlorine gas and the inefficiency of hypochlorite solution dosing systems--due to sociopolitical, economic, and cultural factors--have reduced the utility of these chlorination procedures, especially in far-flung and inaccessible rural communities. These problems led to the development of appropriate technologies for the disinfection of water by means of the on-site generation of mixed oxidant gases (chlorine and ozone). This system, called MOGGOD, operates through the electrolysis of a common salt solution. Simulated system evaluation using a hydraulic model allowed partial and total costs to be calculated. When powered by electrical energy from the community power grid, the system had an efficiency of 90%, and in 10 hours it was able to generate enough gases to disinfect about 200 m3 of water at a cost of approximately N$8 (US $1.30). When the electrolytic cell was run on energy supplied through a photoelectric cell, the investment costs were higher. A system fed by photovoltaic cells could be justified in isolated communities that lack electricity but have a gravity-fed water distribution system.

Emission of nitrous oxide during combustion of organic fuels

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.R.; Gol' dberg, A.S.

1990-11-01

Analyzes formation of nitrogen oxides during combustion of coal, natural gas and mazout: chemical reactions that lead to formation of nitrous oxide during coal combustion, reaction kinetics and reaction yields, factors that influence emission of nitrogen oxides from a furnace, factors that influence formation of nitrous oxide (temperature effects, air excess ratio, coal burnout degree, etc.), effects of fuel type and its chemical composition, effects of flue gas desulfurization and denitrification methods on nitrous oxide yield. Analyses show that yield of nitrous oxide is low and does not exceed 5 cm{sup 3}/m{sup 3} flue gas (0.0005%). However chemical reactions of nitrogen oxides, sulfur dioxide and water vapor in the atmosphere are said to form additional quantities of nitrous oxide which negatively influence the ozone layer. 4 refs.

Impact of ethylene oxide gas sterilization of duodenoscopes after a carbapenem-resistant Enterobacteriaceae outbreak.

Science.gov (United States)

Naryzhny, Igor; Silas, Dean; Chi, Kenneth

2016-08-01

Carbapenem-resistant Enterobacteriaceae (CRE) outbreaks have been implicated at several medical institutions involving gastroenterology laboratories and, specifically, duodenoscopes. Currently, there are no specific guidelines to eradicate or prevent the outbreak of this bacteria. We describe ethylene oxide (ETO) gas sterilizations of duodenoscopes to address this issue. A complete investigation of the gastroenterology laboratory and an evaluation by the Centers for Disease Control and Prevention concluded that no lapses were found in the reprocessing of the equipment. With no deficiencies to address, we began a novel cleaning process using surgical ETO gas sterilizers in addition to standard endoscope reprocessing recommendations and guidelines, all while trying to eradicate the CRE contamination and prevent future recurrences. We also instituted a surveillance system for recurrence of CRE contamination via monthly cultures of the duodenoscopes. Between October 2013 and April 2014, 589 ERCPs were performed with 645 ETO gas sterilizations of 6 duodenoscopes. Given the extra 16 hours needed to sterilize the duodenoscopes, our institution incurred costs resulting from purchasing additional equipment and surveillance cultures. Four duodenoscopes sustained damage during this period; however, this could not be directly attributed to the sterilization process. Furthermore, after an 18-month success period we encountered a positive CRE culture after sterilization, albeit of a different strain than originally detected during the outbreak. The duodenoscope underwent additional ETO gas sterilization, with a negative repeated culture; all potentially exposed individuals screened negative for CRE. Proper use of high-level disinfection alone may not eliminate multidrug-resistant organisms from duodenoscopes. In this single-center study, the addition of ETO sterilization and frequent monitoring with cultures reduced duodenoscope contamination and eliminated clinical infections

Investigation on the combined operation of water gas shift and preferential oxidation reactor system on the kW scale

NARCIS (Netherlands)

O'Connell, M.; Kolb, G.A.; Schelhaas, K.P.; Schuerer, J.; Tiemann, D.; Keller, S.; Reinhard, D.; Hessel, V.

2010-01-01

A 5 kWel water gas shift reactor was integrated with a 5 kWel preferential oxidation reactor for the purposes of reducing the carbon monoxide levels in a reformate exit stream to levels below 100 ppm. The integrated system worked best at partial load with CO concentrations being reduced to 40 ppm at

Photocatalytic Activity of Nanotubular TiO2 Films Obtained by Anodic Oxidation: A Comparison in Gas and Liquid Phase

Directory of Open Access Journals (Sweden)

Beatriz Eugenia Sanabria Arenas

2018-03-01

Full Text Available The availability of immobilized nanostructured photocatalysts is of great importance in the purification of both polluted air and liquids (e.g., industrial wastewaters. Metal-supported titanium dioxide films with nanotubular morphology and good photocatalytic efficiency in both environments can be produced by anodic oxidation, which avoids release of nanoscale materials in the environment. Here we evaluate the effect of different anodizing procedures on the photocatalytic activity of TiO2 nanostructures in gas and liquid phases, in order to identify the most efficient and robust technique for the production of TiO2 layers with different morphologies and high photocatalytic activity in both phases. Rhodamine B and toluene were used as model pollutants in the two media, respectively. It was found that the role of the anodizing electrolyte is particularly crucial, as it provides substantial differences in the oxide specific surface area: nanotubular structures show remarkably different activities, especially in gas phase degradation reactions, and within nanotubular structures, those produced by organic electrolytes lead to better photocatalytic activity in both conditions tested.

Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO₂ Gas Sensor.

Science.gov (United States)

Zou, Bin; Guo, Yunlong; Shen, Nannan; Xiao, Anshan; Li, Mingjun; Zhu, Liang; Wan, Pengbo; Sun, Xiaoming

2017-12-19

Ultrasensitive room temperature real-time NO₂ sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO₂ gas sensors with highly operated temperatures (200-600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultrasensitive NO₂ sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN) nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO) was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO₂ sensing performance (10 ppb to 20 ppm) at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO₂ sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors.

A Customized Metal Oxide Semiconductor-Based Gas Sensor Array for Onion Quality Evaluation: System Development and Characterization

Directory of Open Access Journals (Sweden)

Tharun Konduru

2015-01-01

Full Text Available A gas sensor array, consisting of seven Metal Oxide Semiconductor (MOS sensors that are sensitive to a wide range of organic volatile compounds was developed to detect rotten onions during storage. These MOS sensors were enclosed in a specially designed Teflon chamber equipped with a gas delivery system to pump volatiles from the onion samples into the chamber. The electronic circuit mainly comprised a microcontroller, non-volatile memory chip, and trickle-charge real time clock chip, serial communication chip, and parallel LCD panel. User preferences are communicated with the on-board microcontroller through a graphical user interface developed using LabVIEW. The developed gas sensor array was characterized and the discrimination potential was tested by exposing it to three different concentrations of acetone (ketone, acetonitrile (nitrile, ethyl acetate (ester, and ethanol (alcohol. The gas sensor array could differentiate the four chemicals of same concentrations and different concentrations within the chemical with significant difference. Experiment results also showed that the system was able to discriminate two concentrations (196 and 1964 ppm of methlypropyl sulfide and two concentrations (145 and 1452 ppm of 2-nonanone, two key volatile compounds emitted by rotten onions. As a proof of concept, the gas sensor array was able to achieve 89% correct classification of sour skin infected onions. The customized low-cost gas sensor array could be a useful tool to detect onion postharvest diseases in storage.

WATER-GAS SHIFT KINETICS OVER IRON OXIDE CATALYSTS AT MEMBRANE REACTOR CONDITIONS; A

International Nuclear Information System (INIS)

Carl R.F. Lund

2001-01-01

This report covers the second year of a project investigating water-gas shift catalysts for use in membrane reactors. It has been established that a simple iron high temperature shift catalyst becomes ineffective in a membrane reactor because the reaction rate is severely inhibited by the build-up of the product CO(sub 2). During the past year, an improved microkinetic model for water-gas shift over iron oxide was developed. Its principal advantage over prior models is that it displays the correct asymptotic behavior at all temperatures and pressures as the composition approaches equilibrium. This model has been used to explore whether it might be possible to improve the performance of iron high temperature shift catalysts under conditions of high CO(sub 2) partial pressure. The model predicts that weakening the surface oxygen bond strength by less than 5% should lead to higher catalytic activity as well as resistance to rate inhibition at higher CO(sub 2) partial pressures. Two promoted iron high temperature shift catalysts were studied. Ceria and copper were each studied as promoters since there were indications in the literature that they might weaken the surface oxygen bond strength. Ceria was found to be ineffective as a promoter, but preliminary results with copper promoted FeCr high temperature shift catalyst show it to be much more resistant to rate inhibition by high levels of CO(sub 2). Finally, the performance of sulfided CoMo/Al(sub 2)O(sub 3) catalysts under conditions of high CO(sub 2) partial pressure was simulated using an available microkinetic model for water-gas shift over this catalyst. The model suggests that this catalyst might be quite effective in a medium temperature water-gas shift membrane reactor, provided that the membrane was resistant to the H(sub 2)S that is required in the feed

Energy Efficiency and Renewable Energy Research, Development, and Deployment in Meeting Greenhouse Gas Mitigation Goals. The Case of the Lieberman-Warner Climate Security Act of 2007 (S. 2191)

Energy Technology Data Exchange (ETDEWEB)

Showalter, Sharon [OnLocation, Inc./ Energy Systems Consulting, Vienna, VA (United States); Wood, Frances [OnLocation, Inc./ Energy Systems Consulting, Vienna, VA (United States); Vimmerstedt, Laura [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2010-06-01

The U.S. federal government is considering actions to reduce greenhouse gas emissions. Renewable energy and energy efficiency technologies could help reduce greenhouse gas emissions, so the cost of these technologies could significantly influence the overall cost of meeting greenhouse gas limits. This paper examines the potential benefit of reduced technology cost by analyzing the case of the Lieberman-Warner Climate Security Act of 2007 (S.2191). This act had a goal of reducing national carbon emissions in 2050 to levels 72 percent below 2006 emission levels. In April 2008, the U.S. Department of Energy, Energy Information Administration (EIA) published an analysis of the effects of S.2191 on the U.S. energy sector. This report presents a similar analysis: both analyses examined the impacts of S.2191, and both used versions of the National Energy Modeling System. The analysis reported here used modified technology assumptions to reflect U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) program goals. The results show that achieving EERE program goals could reduce the cost of meeting greenhouse gas limits, reduce the cost of renewable electricity generation and biofuels, and reduce energy intensity.

Energy Efficiency and Renewable Energy Research, Development, and Deployment in Meeting Greenhouse Gas Mitigation Goals: The Case of the Lieberman-Warner Climate Security Act of 2007 (S.2191)

Energy Technology Data Exchange (ETDEWEB)

Showalter, S.; Wood, F.; Vimmerstedt, L.

2010-06-01

The U.S. federal government is considering actions to reduce greenhouse gas emissions. Renewable energy and energy efficiency technologies could help reduce greenhouse gas emissions, so the cost of these technologies could significantly influence the overall cost of meeting greenhouse gas limits. This paper examines the potential benefit of reduced technology cost by analyzing the case of the Lieberman-Warner Climate Security Act of 2007 (S.2191). This act had a goal of reducing national carbon emissions in 2050 to levels 72 percent below 2006 emission levels. In April 2008, the U.S. Department of Energy, Energy Information Administration (EIA) published an analysis of the effects of S.2191 on the U.S. energy sector. This report presents a similar analysis: both analyses examined the impacts of S.2191, and both used versions of the National Energy Modeling System. The analysis reported here used modified technology assumptions to reflect U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) program goals. The results show that achieving EERE program goals could reduce the cost of meeting greenhouse gas limits, reduce the cost of renewable electricity generation and biofuels, and reduce energy intensity.

Nitrous oxide production and consumption: regulation of gene expression by gas-sensitive transcription factors

Science.gov (United States)

Spiro, Stephen

2012-01-01

Several biochemical mechanisms contribute to the biological generation of nitrous oxide (N2O). N2O generating enzymes include the respiratory nitric oxide (NO) reductase, an enzyme from the flavo-diiron family, and flavohaemoglobin. On the other hand, there is only one enzyme that is known to use N2O as a substrate, which is the respiratory N2O reductase typically found in bacteria capable of denitrification (the respiratory reduction of nitrate and nitrite to dinitrogen). This article will briefly review the properties of the enzymes that make and consume N2O, together with the accessory proteins that have roles in the assembly and maturation of those enzymes. The expression of the genes encoding the enzymes that produce and consume N2O is regulated by environmental signals (typically oxygen and NO) acting through regulatory proteins, which, either directly or indirectly, control the frequency of transcription initiation. The roles and mechanisms of these proteins, and the structures of the regulatory networks in which they participate will also be reviewed. PMID:22451107

Nitrous oxide production and consumption: regulation of gene expression by gas-sensitive transcription factors.

Science.gov (United States)

Spiro, Stephen

2012-05-05

Several biochemical mechanisms contribute to the biological generation of nitrous oxide (N(2)O). N(2)O generating enzymes include the respiratory nitric oxide (NO) reductase, an enzyme from the flavo-diiron family, and flavohaemoglobin. On the other hand, there is only one enzyme that is known to use N(2)O as a substrate, which is the respiratory N(2)O reductase typically found in bacteria capable of denitrification (the respiratory reduction of nitrate and nitrite to dinitrogen). This article will briefly review the properties of the enzymes that make and consume N(2)O, together with the accessory proteins that have roles in the assembly and maturation of those enzymes. The expression of the genes encoding the enzymes that produce and consume N(2)O is regulated by environmental signals (typically oxygen and NO) acting through regulatory proteins, which, either directly or indirectly, control the frequency of transcription initiation. The roles and mechanisms of these proteins, and the structures of the regulatory networks in which they participate will also be reviewed.

Reversible solid oxide fuel cell for natural gas/renewable hybrid power generation systems

Science.gov (United States)

Luo, Yu; Shi, Yixiang; Zheng, Yi; Cai, Ningsheng

2017-02-01

Renewable energy (RE) is expected to be the major part of the future energy. Presently, the intermittence and fluctuation of RE lead to the limitation of its penetration. Reversible solid oxide fuel cell (RSOFC) as the energy storage device can effectively store the renewable energy and build a bidirectional connection with natural gas (NG). In this paper, the energy storage strategy was designed to improve the RE penetration and dynamic operation stability in a distributed system coupling wind generators, internal combustion engine, RSOFC and lithium-ion batteries. By compromising the relative deviation of power supply and demand, RE penetration, system efficiency and capacity requirement, the strategy that no more than 36% of the maximum wind power output is directly supplied to users and the other is stored by the combination of battery and reversible solid oxide fuel cell is optimal for the distributed system. In the case, the RE penetration reached 56.9% and the system efficiency reached 55.2%. The maximum relative deviation of power supply and demand is also lower than 4%, which is significantly superior to that in the wind curtailment case.

Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO2 Gas Sensor

OpenAIRE

Zou, Bin; Guo, Yunlong; Shen, Nannan; Xiao, Anshan; Li, Mingjun; Zhu, Liang; Wan, Pengbo; Sun, Xiaoming

2017-01-01

Ultrasensitive room temperature real-time NO2 sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO2 gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultr...

UK emissions of the greenhouse gas nitrous oxide

Science.gov (United States)

Skiba, U.; Jones, S. K.; Dragosits, U.; Drewer, J.; Fowler, D.; Rees, R. M.; Pappa, V. A.; Cardenas, L.; Chadwick, D.; Yamulki, S.; Manning, A. J.

2012-01-01

Signatories of the Kyoto Protocol are obliged to submit annual accounts of their anthropogenic greenhouse gas emissions, which include nitrous oxide (N2O). Emissions from the sectors industry (3.8 Gg), energy (14.4 Gg), agriculture (86.8 Gg), wastewater (4.4 Gg), land use, land-use change and forestry (2.1 Gg) can be calculated by multiplying activity data (i.e. amount of fertilizer applied, animal numbers) with simple emission factors (Tier 1 approach), which are generally applied across wide geographical regions. The agricultural sector is the largest anthropogenic source of N2O in many countries and responsible for 75 per cent of UK N2O emissions. Microbial N2O production in nitrogen-fertilized soils (27.6 Gg), nitrogen-enriched waters (24.2 Gg) and manure storage systems (6.4 Gg) dominate agricultural emission budgets. For the agricultural sector, the Tier 1 emission factor approach is too simplistic to reflect local variations in climate, ecosystems and management, and is unable to take into account some of the mitigation strategies applied. This paper reviews deviations of observed emissions from those calculated using the simple emission factor approach for all anthropogenic sectors, briefly discusses the need to adopt specific emission factors that reflect regional variability in climate, soil type and management, and explains how bottom-up emission inventories can be verified by top-down modelling. PMID:22451103

Two-dimensional simulation of gas concentration impedance for a planar solid oxide fuel cell

International Nuclear Information System (INIS)

Fadaei, M.; Mohammadi, R.; Ghassemi, M.

2014-01-01

Highlights: • The 2D simulation shows another feature in concentration impedance. • The channel gas transport causes a capacitive behavior. • Anode polarization variation has a significant influence on velocity distribution. • The influence of 2D simulation is important for channel height bigger than 2 mm. - Abstract: This paper presents a two-dimensional model for a planar solid oxide fuel cell (SOFC) anode in order to simulate the steady-state performance characteristics as well as the electrochemical impedance spectra. The developed model couples the mass transport with the electrochemical kinetics. The transient conservation equations (momentum and species equations) are solved numerically and the linear kinetic is used for the anode electrochemistry. In order to solve the system of the nonlinear equations, an in-house code based on the finite volume method is developed and utilized. A parametric study is also carried out and the results are discussed. Results show a capacitive semicircle in the Nyquist plot which is identical to the gas concentration impedance. The simulation results are in good agreement with published data

Thin, High-Flux, Self-Standing, Graphene Oxide Membranes for Efficient Hydrogen Separation from Gas Mixtures.

Science.gov (United States)

Bouša, Daniel; Friess, Karel; Pilnáček, Kryštof; Vopička, Ondřej; Lanč, Marek; Fónod, Kristián; Pumera, Martin; Sedmidubský, David; Luxa, Jan; Sofer, Zdeněk

2017-08-22

The preparation and gas-separation performance of self-standing, high-flux, graphene oxide (GO) membranes is reported. Defect-free, 15-20 μm thick, mechanically stable, unsupported GO membranes exhibited outstanding gas-separation performance towards H 2 /CO 2 that far exceeded the corresponding 2008 Robeson upper bound. Remarkable separation efficiency of GO membranes for H 2 and bulky C 3 or C 4 hydrocarbons was achieved with high flux and good selectivity at the same time. On the contrary, N 2 and CH 4 molecules, with larger kinetic diameter and simultaneously lower molecular weight, relative to that of CO 2 , remained far from the corresponding H 2 /N 2 or H 2 /CH 4 upper bounds. Pore size distribution analysis revealed that the most abundant pores in GO material were those with an effective pore diameter of 4 nm; therefore, gas transport is not exclusively governed by size sieving and/or Knudsen diffusion, but in the case of CO 2 was supplemented by specific interactions through 1) hydrogen bonding with carboxyl or hydroxyl functional groups and 2) the quadrupole moment. The self-standing GO membranes presented herein demonstrate a promising route towards the large-scale fabrication of high-flux, hydrogen-selective gas membranes intended for the separation of H 2 /CO 2 or H 2 /alkanes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas chromatographic determination with electron capture detection of residual ethylene oxide in intraocular lenses

Energy Technology Data Exchange (ETDEWEB)

Kikuchi, H.; Nakamura, A.; Tsuji, K.

1988-01-01

A sensitive method is described to determine trace quantities of ethylene oxide (EO) in EO-sterilized intraocular lenses (IOLs). An IOL is dipped in ethanol containing 0.25 ppm propylene oxide (PO) in a 4 mL vial, 2 drops of freshly distilled hydrobromic acid is added through a septum, and the mixture is warmed at 50/sup 0/C for 24 h. It is then neutralized by vigorous shaking with sodium bicarbonate, dehydrated with anhydrous sodium sulfate, and filtered. The filtrate is injected into a gas chromatograph with electron-capture detection, and the peak height ratio of ethylene bromohydrin/propylene bromohydrin is measured. EO residue is calculated from the calibration curve obtained through a similar procedure with the standard EO/PO solutions. The limit of determination is 0.04 ..mu..g/lens (ca 2.0 ppm). When EO residue levels were determined for IOLs sampled at 3 different aeration periods after stabilization, the authors found that 9 days of aeration was necessary to meet the US Food and Drug Administration proposed limit for EO residue in IOLs.

Superlubricating graphene and graphene oxide films

Science.gov (United States)

Sumant, Anirudha V.; Erdemir, Ali; Choi, Junho; Berman, Diana

2018-02-13

A system and method for forming at least one of graphene and graphene oxide on a substrate and an opposed wear member. The system includes graphene and graphene oxide formed by an exfoliation process or solution processing method to dispose graphene and/or graphene oxide onto a substrate. The system further includes an opposing wear member disposed on another substrate and a gas atmosphere of an inert gas like N2, ambient, a humid atmosphere and a water solution.

Application of near ambient pressure gas-phase X-ray photoelectron spectroscopy to the investigation of catalytic properties of copper in methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Prosvirin, Igor P., E-mail: prosvirin@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Bukhtiyarov, Andrey V., E-mail: avb@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva ave. 5, 630090 Novosibirsk (Russian Federation); Research and Educational Center for Energy Efficient Catalysis, Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Bluhm, Hendrik, E-mail: hbluhm@lbl.gov [Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bukhtiyarov, Valerii I., E-mail: vib@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Research and Educational Center for Energy Efficient Catalysis, Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation)

2016-02-15

Graphical abstract: - Highlights: • Selective oxidation of CH{sub 3}OH to CH{sub 2}O over a Cu foil has been studied by in situ gas phase XPS. • C1s and O1s spectra were used for identification of reagents and reaction products in a gas phase. • Catalytic data (conversions and reaction products yields) calculated from XPS spectra are in a good agreement with QMS results. • The possible reasons of the observed variations in reaction mechanism have been discussed. - Abstract: Application of near ambient pressure (NAP) X-ray photoelectron spectroscopy for characterization of catalytic properties of a heterogeneous catalyst through measurement and analysis of the core-level spectra from gas phase constituents, which become measurable in submillibar pressure range, has been demonstrated for the reaction of methanol oxidation over polycrystalline copper foil. To improve the accuracy of quantitative analysis of the gas phase signals for the routine XPS spectrometer with double Al/Mg anode used in these experiments, the sample was removed from XPS analysis zone, but it was still located in high-pressure gas cell. As consequence, only gas phase peaks from reagents and reaction products have been observed in XPS spectra. Quantitative analysis of the spectra has allowed us to calculate conversions of the reagents and yields of the reaction products, or, other words, to characterize the catalytic properties of the catalyst and to track their changes with temperature. Further comparison of the catalytic properties with concentration of the surface species measured by in situ XPS in separate experiments, but under the same conditions, gives a possibility to discuss the reaction mechanisms.

Dependence of the optical constants and the performance in the SPREE gas measurement on the thickness of doped tin oxide over coatings

Science.gov (United States)

Fischer, D.; Hertwig, A.; Beck, U.; Negendank, D.; Lohse, V.; Kormunda, M.; Esser, N.

2017-11-01

In this study, thickness related changes of the optical properties of doped tin oxide were studied. Two different sets of samples were prepared. The first set was doped with iron or nickel on silicon substrate with thicknesses of 29-56 nm, the second was iron doped on gold/glass substrate with 1.6-6.3 nm. The optical constants were determined by using spectral ellipsometry (SE) followed by modelling of the dielectric function with an oscillator model using Gaussian peaks. The analysis of the optical constants shows a dependence of the refraction and the absorption on the thickness of the doped tin oxide coating. In addition to the tin oxide absorption in the UV, one additional absorption peak was found in the near-IR/red which is related to plasmonic effects due to the doping. This peak shifts from the near-IR to the red part of the visible spectrum and becomes stronger by reducing the thickness, probably due to the formation of metal nanoparticles in this layer. These results were found for two different sets of samples by using the same optical model. Afterwards the second sample set was tested in the Surface Plasmon Resonance Enhanced Ellipsometric (SPREE) gas measurement with CO gas. It was found that the thickness has significant influence on the sensitivity and thus the adsorption of the CO gas. By increasing the thickness from 1.6 nm to 5.1 nm, the sensing ability is enhanced due to a higher coverage of the surface with the over coating. This is explained by the high affinity of CO molecules to the incorporated Fe-nanoparticles in the tin oxide coating. By increasing the thickness further to 6.3 nm, the sensing ability drops because the layer disturbs the SPR sensing effect too much.

Biotransformation of natural gas and oil compounds associated with marine oil discharges.

Science.gov (United States)

Brakstad, Odd Gunnar; Almås, Inger K; Krause, Daniel Franklin

2017-09-01

Field data from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico (GoM) suggested that oxidation of gas compounds stimulated biodegradation of oil compounds in the deep sea plume. We performed experiments with local seawater from a Norwegian fjord to examine if the presence of dissolved gas compounds (methane, ethane and propane) affected biodegradation of volatile oil compounds, and if oil compounds likewise affected gas compound oxidation. The results from the experiment showed comparable oil compound biotransformation rates in seawater at 5 °C between seawater with and without soluble gases. Gas oxidation was not affected by the presence of volatile oil compounds. Contrary to DWH deep sea plume data, propane oxidation was not faster than methane oxidation. These data may reflect variations between biodegradation of oil and gas in seawater environments with different history of oil and gas exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Absorption and oxidation of nitrogen oxide in ionic liquids

DEFF Research Database (Denmark)

Kunov-Kruse, Andreas Jonas; Thomassen, Peter Langelund; Riisager, Anders

2016-01-01

A new strategy for capturing nitrogen oxide, NO, from the gas phase is presented. Dilute NO gas is removed from the gas phase by ionic liquids under ambient conditions. The nitrate anion of the ionic liquid catalyzes the oxidation of NO to nitric acid by atmospheric oxygen in the presence of water....... The nitric acid is absorbed in the ionic liquid up to approximately one mole HNO3 per mole of the ionic liquid due to the formation of hydrogen bonds. The nitric acid can be desorbed by heating, thereby regenerating the ionic liquid with excellent reproducibility. Here, time-resolved in-situ spectroscopic...... investigations of the reaction and products are presented. The procedure reveals a new vision for removing the pollutant NO by absorption into a non-volatile liquid and converting it into a useful bulk chemical, that is, HNO3....

Tuning the conductivity threshold and carrier density of two-dimensional electron gas at oxide interfaces through interface engineering

Directory of Open Access Journals (Sweden)

H. J. Harsan Ma

2015-08-01

Full Text Available The two-dimensional electron gas (2DEG formed at the perovskite oxides heterostructures is of great interest because of its potential applications in oxides electronics and nanoscale multifunctional devices. A canonical example is the 2DEG at the interface between a polar oxide LaAlO3 (LAO and non-polar SrTiO3 (STO. Here, the LAO polar oxide can be regarded as the modulating or doping layer and is expected to define the electronic properties of 2DEG at the LAO/STO interface. However, to practically implement the 2DEG in electronics and device design, desired properties such as tunable 2D carrier density are necessary. Here, we report the tuning of conductivity threshold, carrier density and electronic properties of 2DEG in LAO/STO heterostructures by insertion of a La0.5Sr0.5TiO3 (LSTO layer of varying thicknesses, and thus modulating the amount of polarization of the oxide over layers. Our experimental result shows an enhancement of carrier density up to a value of about five times higher than that observed at the LAO/STO interface. A complete thickness dependent metal-insulator phase diagram is obtained by varying the thickness of LAO and LSTO providing an estimate for the critical thickness needed for the metallic phase. The observations are discussed in terms of electronic reconstruction induced by polar oxides.

Recovery of vanadium oxide

International Nuclear Information System (INIS)

Bates, C.P.; Clark, N.E.

1985-01-01

This invention relates to the recovery of vanadium oxide from molten metal. The invention provides a method for recovering vanadium oxide from molten metal, which includes passing oxygen and at least one coolant gas or shroud into the molten metal by way of at least one elongate lance. The invention also provides an arrangement for the recovery of vanadium oxide from molten metal, which includes at least one elongate lance extending into the molten metal. The lance is provided with at least one elongate bore extending therethrough. Means are provided to allow at least oxygen and at least one coolant gas to pass through the lance and into the molten metal

Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications

Directory of Open Access Journals (Sweden)

Yousri M.A. Welaya

2013-12-01

Full Text Available Strong restrictions on emissions from marine power plants (particularly SOx, NOx will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heat-recovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications

Science.gov (United States)

Welaya, Yousri M. A.; Mosleh, M.; Ammar, Nader R.

2013-12-01

Strong restrictions on emissions from marine power plants (particularly SOx, NOx) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heatrecovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

Gas phase deposition of oxide and metal-oxide coatings on fuel particles

International Nuclear Information System (INIS)

Patokin, A.P.; Khrebtov, V.L.; Shirokov, B.M.

2008-01-01

Production processes and properties of oxide (Al 2 O 3 , ZrO 2 ) and metal-oxide (Mo-Al 2 O 3 , Mo-ZrO 2 , W-Al 2 O 3 , W-ZrO 2 ) coatings on molybdenum substrates and uranium dioxide fuel particles were investigated. It is shown that the main factors that have an effect on the deposition rate, density, microstructure and other properties of coatings are the deposition temperature, the ratio of H 2 and CO 2 flow rates, the total reactor pressure and the ratio of partial pressures of corresponding metal chlorides during formation of metal-oxide coatings

Gas sensor

International Nuclear Information System (INIS)

Dorogan, V.; Korotchenkov, Gh.; Vieru, T.; Prodan, I.

2003-01-01

The invention relates to the gas sensors on base of metal-oxide films (SnO, InO), which may be used for enviromental control, in the fireextinguishing systema etc. The gas includes an insulating substrate, an active layer, a resistive layer with ohmic contacts. The resistive layer has two or more regions with dofferent resistances , and on the active layer are two or more pairs of ohmic contacts

Compositional simulations of producing oil-gas ratio behaviour in low permeable gas condensate reservoir

OpenAIRE

Gundersen, Pål Lee

2013-01-01

Master's thesis in Petroleum engineering Gas condensate flow behaviour below the dew point in low permeable formations can make accurate fluid sampling a difficult challenge. The objective of this study was to investigate the producing oil-gas ratio behaviour in the infinite-acting period for a low permeable gas condensate reservoir. Compositional isothermal flow simulations were performed using a single-layer, radial and two-dimensional, gas condensate reservoir model with low permeabili...

Gas-phase fragmentation of coordination compounds: loss of CO(2) from inorganic carbonato complexes to give metal oxide ions

Science.gov (United States)

Dalgaard; McKenzie

1999-10-01

Using electrospray ionization mass spectrometry, novel transition metal oxide coordination complex ions are proposed as the products of the collision-induced dissociation (CID) of some carbonato complex ions through the loss of a mass equivalent to CO(2). CID spectra of [(tpa)CoCO(3)](+) (tpa = tris(2-pyridylmethyl)methylamine), [(bispicMe(2)en)Fe(&mgr;-O)(&mgr;-CO(3))Fe(bispicMe(2)en)]2+ (bispicMe(2)en = N,N'-dimethyl-N,N'-bis(2-pyridylmethy)eth- ane-1, 2-diamine) and [(bpbp)Cu(2)CO(3)](+) (bpbp(-) = bis[(bis-(2-pyridylmethyl)amino)methyl]-4-tertbutylpheno-lato(1-)), show peaks assigned to the mono- and dinuclear oxide cations, [(tpa)CoO](+), [(bispicMe(2)en)(2)Fe(2)(O)(2)]2+ and [(bpbp)Cu(2)O](+), as the dominant species. These results can be likened to the reverse of typical synthetic reactions in which metal hydroxide compounds react with CO(2) to give metal carbonato compounds. Because of the lack of available protons in the gas phase, novel oxide species rather than the more common hydroxide ions are generated. These oxide ions are relevant to the highly oxidizing species proposed in oxygenation reactions catalysed by metal oxides and metalloenzymes. Copyright 1999 John Wiley & Sons, Ltd.

Kolkhoung (Pistacia khinjuk) Hull Oil and Kernel Oil as Antioxidative Vegetable Oils with High Oxidative Stability 
and Nutritional Value.

Science.gov (United States)

Asnaashari, Maryam; Hashemi, Seyed Mohammad Bagher; Mehr, Hamed Mahdavian; Yousefabad, Seyed Hossein Asadi

2015-03-01

In this study, in order to introduce natural antioxidative vegetable oil in food industry, the kolkhoung hull oil and kernel oil were extracted. To evaluate their antioxidant efficiency, gas chromatography analysis of the composition of kolkhoung hull and kernel oil fatty acids and high-performance liquid chromatography analysis of tocopherols were done. Also, the oxidative stability of the oil was considered based on the peroxide value and anisidine value during heating at 100, 110 and 120 °C. Gas chromatography analysis showed that oleic acid was the major fatty acid of both types of oil (hull and kernel) and based on a low content of saturated fatty acids, high content of monounsaturated fatty acids, and the ratio of ω-6 and ω-3 polyunsaturated fatty acids, they were nutritionally well--balanced. Moreover, both hull and kernel oil showed high oxidative stability during heating, which can be attributed to high content of tocotrienols. Based on the results, kolkhoung hull oil acted slightly better than its kernel oil. However, both of them can be added to oxidation-sensitive oils to improve their shelf life.

Gas-Phase Thermolyses

DEFF Research Database (Denmark)

Carlsen, Lars; Egsgaard, Helge

1982-01-01

The unimolecular gas-phase thermolyses of 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide have been studied by the flash vacuum thermolysis–field ionization mass spectrometry (f.v.t.–f.i.m.s.) technique in the temperature range from 1 043 to 1 404 K. The reactions are rationalized in terms of sulp...

Oxidation of elemental mercury by modified spent TiO2-based SCR-DeNOx catalysts in simulated coal-fired flue gas.

Science.gov (United States)

Zhao, Lingkui; Li, Caiting; Zhang, Xunan; Zeng, Guangming; Zhang, Jie; Xie, Yin'e

2016-01-01

In order to reduce the costs, the recycle of spent TiO2-based SCR-DeNOx catalysts were employed as a potential catalytic support material for elemental mercury (Hg(0)) oxidation in simulated coal-fired flue gas. The catalytic mechanism for simultaneous removal of Hg(0) and NO was also investigated. The catalysts were characterized by Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) method. Results indicated that spent TiO2-based SCR-DeNOx catalyst supported Ce-Mn mixed oxides catalyst (CeMn/SCR1) was highly active for Hg(0) oxidation at low temperatures. The Ce1.00Mn/SCR1 performed the best catalytic activities, and approximately 92.80% mercury oxidation efficiency was obtained at 150 °C. The inhibition effect of NH3 on Hg(0) oxidation was confirmed in that NH3 consumed the surface oxygen. Moreover, H2O inhibited Hg(0) oxidation while SO2 had a promotional effect with the aid of O2. The XPS results illustrated that the surface oxygen was responsible for Hg(0) oxidation and NO conversion. Besides, the Hg(0) oxidation and NO conversion were thought to be aided by synergistic effect between the manganese and cerium oxides.

Interfacial-Bonding-Regulated CO Oxidation over Pt Atoms Immobilized on Gas-Exfoliated Hexagonal Boron Nitride

KAUST Repository

Liu, Xin

2017-10-12

We compared the electronic structure and CO oxidation mechanisms over Pt atoms immobilized by both B-vacancies and N-vacancies on gas-exfoliated hexagonal boron nitride. We showed that chemical bonds are formed between the B atoms associated with dangling bonds around the vacancies and Pt atoms. These bonds not only alter the thermodynamics and kinetics for the aggregation and effectively immobilize Pt atoms, but also significantly change the composition and energetic distribution of the electronic states of the composites to circumvent CO poisoning and to favour coadsorption of CO and O2, which further regulates the reactions to proceed through a Langmuir-Hinshelwood mechanism. The CO oxidation over Pt atoms immobilized at N-vacancies involves formation of an intermediate with –C(O)-O−O- bonded to Pt, the generation of CO2 by peroxo O−O bond scission and the reduction of the remnant oxygen, and the calculated energy barriers are 0.49, 0.23 and 0.18 eV, respectively. Such small energy barriers are comparable to those over Pt atoms trapped at B-vacancies, showing the effectiveness of Pt/hexagonal boron nitride atomic composites as catalysts for CO oxidation. These findings also suggest the feasibility of regulating the reaction pathways over single atom catalysts via interfacial engineering.

Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation

Directory of Open Access Journals (Sweden)

Ricardo López Antón

2017-03-01

Full Text Available Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h. The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased and soft (unbiased components; however, the precise origin of the soft phase is as yet unresolved.

Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere

Science.gov (United States)

van Sebille, M.; Fusi, A.; Xie, L.; Ali, H.; van Swaaij, R. A. C. M. M.; Leifer, K.; Zeman, M.

2016-09-01

We report the effect of hydrogen on the crystallization process of silicon nanocrystals embedded in a silicon oxide matrix. We show that hydrogen gas during annealing leads to a lower sub-band gap absorption, indicating passivation of defects created during annealing. Samples annealed in pure nitrogen show expected trends according to crystallization theory. Samples annealed in forming gas, however, deviate from this trend. Their crystallinity decreases for increased annealing time. Furthermore, we observe a decrease in the mean nanocrystal size and the size distribution broadens, indicating that hydrogen causes a size reduction of the silicon nanocrystals.

Quantification of Nitrous Oxide from Fugitive Emissions by Tracer Dilution Method using a Mobile Real-time Nitrous Oxide Analyzer

Science.gov (United States)

Mønster, J.; Rella, C.; Jacobson, G. A.; He, Y.; Hoffnagle, J.; Scheutz, C.

2012-12-01

Nitrous oxide is a powerful greenhouse gas considered 298 times stronger than carbon dioxide on a hundred years term (Solomon et al. 2007). The increasing global concentration is of great concern and is receiving increasing attention in various scientific and industrial fields. Nitrous oxide is emitted from both natural and anthropogenic sources. Inventories of source specific fugitive nitrous oxide emissions are often estimated on the basis of modeling and mass balance. While these methods are well-developed, actual measurements for quantification of the emissions can be a useful tool for verifying the existing estimation methods as well as providing validation for initiatives targeted at lowering unwanted nitrous oxide emissions. One approach to performing such measurements is the tracer dilution method (Galle et al. 2001), in which a tracer gas is released at the source location at a known flow. The ratio of downwind concentrations of both the tracer gas and nitrous oxide gives the ratios of the emissions rates. This tracer dilution method can be done with both stationary and mobile measurements; in either case, real-time measurements of both tracer and analyte gas is required, which places high demands on the analytical detection method. To perform the nitrous oxide measurements, a novel, robust instrument capable of real-time nitrous oxide measurements has been developed, based on cavity ring-down spectroscopy and operating in the near-infrared spectral region. We present the results of the laboratory and field tests of this instrument in both California and Denmark. Furthermore, results are presented from measurements using the mobile plume method with a tracer gas (acetylene) to quantify the nitrous oxide and methane emissions from known sources such as waste water treatment plants and composting facilities. Nitrous oxide (blue) and methane (yellow) plumes downwind from a waste water treatment facility.

A novel polygeneration process to co-produce ethylene and electricity from shale gas with zero CO2 emissions via methane oxidative coupling

International Nuclear Information System (INIS)

Khojasteh Salkuyeh, Yaser; Adams, Thomas A.

2015-01-01

Highlights: • Development of an ethylene plant from shale gases with zero CO 2 emissions. • Oxidative coupling of methane is used for the conversion of gas to ethylene. • Polygeneration strategy is used to improve the profitability of plant. - Abstract: A techno-economic analysis of a novel process to co-produce ethylene and electricity using a recently developed methane oxidative coupling catalyst is presented. Several design variants are considered, featuring the use of traditional gas turbines, chemical looping combustion, and 100% carbon dioxide capture. Mass and energy balance simulations were carried out using Aspen Plus simulations, and particle swarm optimization was used to determine the optimal process design under a variety of market scenarios. A custom model for the gas turbine section was used to ensure that the negative impacts of various cooling strategies were factored into the analysis. The results show that by synergistically co-producing power and ethylene using this catalyst, ethylene can be produced at costs close to traditional steam cracking methods with nearly zero carbon dioxide emissions, even when factoring in the relatively poor conversion and selectivity of the chosen catalyst

Unintended inhalation of nitric oxide by contamination of compressed air: physiologic effects and interference with intended nitric oxide inhalation in acute lung injury.

Science.gov (United States)

Benzing, A; Loop, T; Mols, G; Geiger, K

1999-10-01

Compressed air from a hospital's central gas supply may contain nitric oxide as a result of air pollution. Inhaled nitric oxide may increase arterial oxygen tension and decrease pulmonary vascular resistance in patients with acute lung injury and acute respiratory distress syndrome. Therefore, the authors wanted to determine whether unintentional nitric oxide inhalation by contamination of compressed air influences arterial oxygen tension and pulmonary vascular resistance and interferes with the therapeutic use of nitric oxide. Nitric oxide concentrations in the compressed air of a university hospital were measured continuously by chemiluminescence during two periods (4 and 2 weeks). The effects of unintended nitric oxide inhalation on arterial oxygen tension (n = 15) and on pulmonary vascular resistance (n = 9) were measured in patients with acute lung injury and acute respiratory distress syndrome by changing the source of compressed air of the ventilator from the hospital's central gas supply to a nitric oxide-free gas tank containing compressed air. In five of these patients, the effects of an additional inhalation of 5 ppm nitric oxide were evaluated. During working days, compressed air of the hospital's central gas supply contained clinically effective nitric oxide concentrations (> 80 parts per billion) during 40% of the time. Change to gas tank-supplied nitric oxide-free compressed air decreased the arterial oxygen tension by 10% and increased pulmonary vascular resistance by 13%. The addition of 5 ppm nitric oxide had a minimal effect on arterial oxygen tension and pulmonary vascular resistance when added to hospital-supplied compressed air but improved both when added to tank-supplied compressed air. Unintended inhalation of nitric oxide increases arterial oxygen tension and decreases pulmonary vascular resistance in patients with acute lung injury and acute respiratory distress syndrome. The unintended nitric oxide inhalation interferes with the

Surface plasmon resonance-based fiber-optic hydrogen gas sensor utilizing palladium supported zinc oxide multilayers and their nanocomposite.

Science.gov (United States)

Tabassum, Rana; Gupta, Banshi D

2015-02-10

We analyze surface plasmon resonance-based fiber-optic sensor for sensing of small concentrations of hydrogen gas in the visible region of the electromagnetic spectrum. One of the two probes considered has multilayers of zinc oxide (ZnO) and palladium (Pd) while the other has layer of their composite over a silver coated unclad core of the fiber. The analysis is carried out for different volume fractions of palladium nanoparticles dispersed in zinc oxide host material in the nanocomposite layer. For the analysis, a Maxwell-Garnett model is adopted for calculating the dielectric function of a ZnO:Pd nanocomposite having nanoparticles of dimensions smaller than the wavelength of radiation used. The effects of the volume fraction of the nanoparticles in the nanocomposite and the thickness of the nanocomposite layer on the figure of merit of the sensor have been studied. The film thickness of the layer and the volume fraction of nanoparticles in the ZnO:Pd nanocomposite layer have been optimized to achieve the maximum value of the figure of merit of the sensor. It has been found that the figure of merit of the sensing probe coated with ZnO:Pd nanocomposite is more than twofold of the sensing probe coated with multilayers of Pd and ZnO over a silver coated unclad core of the fiber; hence, the sensor with a nanocomposite layer works better than that with multilayers of zinc oxide and palladium. The sensor can be used for online monitoring and remote sensing of hydrogen gas.

Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

Directory of Open Access Journals (Sweden)

Konrad Maier

2015-09-01

Full Text Available In this work the low temperature response of metal oxide semiconductor gas sensors is analyzed. Important characteristics of this low-temperature response are a pronounced selectivity to acid- and base-forming gases and a large disparity of response and recovery time constants which often leads to an integrator-type of gas response. We show that this kind of sensor performance is related to the trend of semiconductor gas sensors to adsorb water vapor in multi-layer form and that this ability is sensitively influenced by the surface morphology. In particular we show that surface roughness in the nanometer range enhances desorption of water from multi-layer adsorbates, enabling them to respond more swiftly to changes in the ambient humidity. Further experiments reveal that reactive gases, such as NO2 and NH3, which are easily absorbed in the water adsorbate layers, are more easily exchanged across the liquid/air interface when the humidity in the ambient air is high.

UV-laser-light-controlled photoluminescence of metal oxide nanoparticles in different gas atmospheres: BaTiO3, SrTiO3 and HfO2

International Nuclear Information System (INIS)

Mochizuki, Shosuke; Saito, Takashi; Yoshida, Kaori

2012-01-01

The photoluminescence (PL) enhancement has been studied at room temperature using various specimen atmospheres (O 2 gas, CO 2 gas, CO 2 -H 2 mixture gas, Ar-H 2 mixture gas and vacuum) under 325 nm laser light irradiation on various metal oxides. Of them, the results obtained for BaTiO 3 nanocrystals, SrTiO 3 ones and HfO 2 powder crystal are given in the present paper. Their PL were considerably increased in intensity by irradiation of 325 nm laser light in CO 2 gas and CO 2 -H 2 mixture gas. The cause of the PL intensity enhancements is discussed in the light of the exciton theory, the defect chemistry and the photocatalytic theory. The results may be applied for the utilization of greenhouse gas (CO 2 ) and the optical sensor for CO 2 gas.

Oxidation catalysts on alkaline earth supports

Science.gov (United States)

Mohajeri, Nahid

2017-03-21

An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

Atmospheric oxidation of 1,3-butadiene: characterization of gas and aerosol reaction products and implication for PM2.5

Science.gov (United States)

Jaoui, M.; Lewandowski, M.; Docherty, K.; Offenberg, J. H.; Kleindienst, T. E.

2014-06-01

Secondary organic aerosol (SOA) was generated by irradiating 1,3-butadiene (13BD) in the presence of H2O2 or NOx. Experiments were conducted in a smog chamber operated in either flow or batch mode. A filter/denuder sampling system was used for simultaneously collecting gas- and particle-phase products. The chemical composition of the gas phase and SOA was analyzed using derivative-based methods (BSTFA, BSTFA + PFBHA, or DNPH) followed by gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC) analysis of the derivative compounds. The analysis showed the occurrence of more than 60 oxygenated organic compounds in the gas and particle phases, of which 31 organic monomers were tentatively identified. The major identified products include glyceric acid, d-threitol, erythritol, d-threonic acid, meso-threonic acid, erythrose, malic acid, tartaric acid, and carbonyls including glycolaldehyde, glyoxal, acrolein, malonaldehyde, glyceraldehyde, and peroxyacryloyl nitrate (APAN). Some of these were detected in ambient PM2.5 samples and could potentially serve as organic markers of 1,3-butadiene (13BD). Furthermore, a series of oligoesters were detected and found to be produced from esterification reactions among compounds bearing alcoholic groups and compounds bearing acidic groups. Time profiles are provided for selected compounds. SOA was analyzed for organic mass to organic carbon (OM / OC) ratio, effective enthalpy of vaporization (ΔHvapeff), and aerosol yield. The average OM / OC ratio and SOA density were 2.7 ± 0.09 and 1.2 ± 0.05, respectively. The average ΔHvapeff was 26.1 ± 1.5 kJ mol-1, a value lower than that of isoprene SOA. The average laboratory SOA yield measured in this study at aerosol mass concentrations between 22.5 and 140.2 μg m-3 was 0.025 ± 0.011, a value consistent with the literature (0.021-0.178). While the focus of this study has been examination of the particle-phase measurements, the gas

Atmospheric oxidation of 1,3-butadiene: characterization of gas and aerosol reaction products and implications for PM2.5

Science.gov (United States)

Jaoui, M.; Lewandowski, M.; Docherty, K.; Offenberg, J. H.; Kleindienst, T. E.

2014-12-01

Secondary organic aerosol (SOA) was generated by irradiating 1,3-butadiene (13BD) in the presence of H2O2 or NOx. Experiments were conducted in a smog chamber operated in either flow or batch mode. A filter/denuder sampling system was used for simultaneously collecting gas- and particle-phase products. The chemical composition of the gas phase and SOA was analyzed using derivative-based methods (BSTFA, BSTFA + PFBHA, or DNPH) followed by gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC) analysis of the derivative compounds. The analysis showed the occurrence of more than 60 oxygenated organic compounds in the gas and particle phases, of which 31 organic monomers were tentatively identified. The major identified products include glyceric acid, d-threitol, erythritol, d-threonic acid, meso-threonic acid, erythrose, malic acid, tartaric acid, and carbonyls including glycolaldehyde, glyoxal, acrolein, malonaldehyde, glyceraldehyde, and peroxyacryloyl nitrate (APAN). Some of these were detected in ambient PM2.5 samples, and could potentially serve as organic markers of 13BD. Furthermore, a series of oligoesters were detected and found to be produced through chemical reactions occurring in the aerosol phase between compounds bearing alcoholic groups and compounds bearing acidic groups. SOA was analyzed for organic mass to organic carbon (OM /OC) ratio, effective enthalpy of vaporization (Δ Hvapeff), and aerosol yield. The average OM /OC ratio and SOA density were 2.7 ± 0.09 and 1.2 ± 0.05, respectively. The average Δ Hvapeff was -26.08 ± 1.46 kJ mol-1, a value lower than that of isoprene SOA. The average laboratory SOA yield measured in this study at aerosol mass concentrations between 22.5 and 140.2 μg m-3 was 0.025 ± 0.011, a value consistent with the literature (0.021-0.178). While the focus of this study has been examination of the particle-phase measurements, the gas-phase photooxidation products have also been

7 CFR 2900.4 - Natural gas requirements.

Science.gov (United States)

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Natural gas requirements. 2900.4 Section 2900.4..., DEPARTMENT OF AGRICULTURE ESSENTIAL AGRICULTURAL USES AND VOLUMETRIC REQUIREMENTS-NATURAL GAS POLICY ACT § 2900.4 Natural gas requirements. For purposes of Section 401(c), NGPA, the natural gas requirements for...

Selective oxidation

International Nuclear Information System (INIS)

Cortes Henao, Luis F.; Castro F, Carlos A.

2000-01-01

It is presented a revision and discussion about the characteristics and factors that relate activity and selectivity in the catalytic and not catalytic partial oxidation of methane and the effect of variables as the temperature, pressure and others in the methane conversion to methanol. It thinks about the zeolites use modified for the catalytic oxidation of natural gas

Magnetic susceptibility as a direct measure of oxidation state in LiFePO4 batteries and cyclic water gas shift reactors.