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Sample records for acyl-coa dehydrogenation deficiency

  1. Fuel utilization in patients with very long-chain acyl-coa dehydrogenase deficiency

    DEFF Research Database (Denmark)

    ØRngreen, Mette C; Nørgaard, Mette; Sacchetti, Massimo

    2004-01-01

    Fuel utilization in two adult patients with the myopathic form of very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency and five healthy subjects was investigated with stable isotopes during exercise at 50% of VO2max. The findings indicate that residual VLCAD activity in the patients...

  2. Lipid-storage myopathy and respiratory insufficiency due to ETFQO mutations in a patient with late-onset multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, R K J; Pourfarzam, M; Morris, A A M

    2004-01-01

    We report a patient with lipid-storage myopathy due to multiple acyl-CoA dehydrogenation deficiency (MADD). Molecular genetic analysis showed that she was compound heterozygous for mutations in the gene for electron transfer flavoprotein:ubiquinone oxidoreductase (ETFQO). Despite a good initial r...

  3. The ETFDH c.158A>G Variation Disrupts the Balanced Binding of ESE and ESS Proteins Causing Missplicing and Multiple acyl-CoA Dehydrogenation Deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Brøner, Sabrina; Sabaratnam, Rugivan

    2013-01-01

    Multiple acyl-CoA dehydrogenation deficiency is a disorder of fatty acid and amino acid oxidation caused by defects of electron transfer flavoprotein (ETF) or its dehydrogenase (ETFDH). A clear relationship between genotype and phenotype makes genotyping of patients important not only diagnostica......Multiple acyl-CoA dehydrogenation deficiency is a disorder of fatty acid and amino acid oxidation caused by defects of electron transfer flavoprotein (ETF) or its dehydrogenase (ETFDH). A clear relationship between genotype and phenotype makes genotyping of patients important not only......-down of nuclear proteins, we show that the c.158A>G variation increases the strength of a preexisting exonic splicing silencer (ESS) motif UAGGGA. This ESS motif binds splice inhibitory hnRNP A1, hnRNP A2/B1, and hnRNP H proteins. Binding of these inhibitory proteins prevents binding of the positive splicing...

  4. Transient multiple acyl-CoA dehydrogenation deficiency in a newborn female caused by maternal riboflavin deficiency

    DEFF Research Database (Denmark)

    Chiong, M A; Sim, K G; Carpenter, K

    2007-01-01

    A newborn female presented on the first day of life with clinical and biochemical findings consistent with multiple acyl-CoA dehydrogenase deficiency (MADD). Riboflavin supplementation corrected the biochemical abnormalities 24 h after commencing the vitamin. In vitro acylcarnitine profiling...

  5. Decarbonylation and dehydrogenation of carbohydrates

    Science.gov (United States)

    Andrews, Mark A.; Klaeren, Stephen A.

    1991-01-01

    Carbohydrates, especially aldose or ketose sugars, including those whose carbonyl group is masked by hemi-acetal or hemi-ketal formation, are decarbonylated by heating the feed carbohydrate together with a transition metal complex in a suitable solvent. Also, primary alcohols, including sugar alditols are simultaneously dehydrogenated and decarbonylated by heating a mixture of rhodium and ruthenium complexes and the alcohol and optionally a hydrogen acceptor in an acceptable solvent. Such defarbonylation and/or dehydrogenation of sugars provides a convenient procedure for the synthesis of certain carbohydrates and may provide a means for the conversion of biomass into useful products.

  6. Deficiencies

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of all deficiencies currently listed on Nursing Home Compare, including the nursing home that received the deficiency, the associated inspection date,...

  7. Supported organoiridium catalysts for alkane dehydrogenation

    Science.gov (United States)

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  8. High fat fed heart failure animals have enhanced mitochondrial function and acyl-coa dehydrogenase activities

    Science.gov (United States)

    We have previously shown that administration of high fat in heart failure (HF) increased mitochondrial respiration and did not alter left ventricular (LV) function. PPARalpha is a nuclear transcription factor that activates expression of genes involved in fatty acid uptake and utilization. We hypoth...

  9. Catalytic Conversion of Methanol by Oxidative Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study investigates the effects of addition of oxygen on the oxidative dehydrogenation (ODH) of methanol when a fluorotetrasilicic mica ion-exchanged with palladium (Pd2+-TSM) was used as the catalyst. The reaction proceeded at a very low temperature in the presence of oxygen, and HCOOCH3 was obtained at high selectivity. By calculating the equilibrium conversion, it has been shown that substantial ODH took place for HCOOCH3 production. Consequently, this reaction would make dehydrogenation the dominant reaction at equilibrium. Not all the H dissociated from CH3OH was converted to H2O by oxidation. It has been shown that the H2O was not produced from oxidative dehydrogenation by the direct reaction of CH3OH and O2 when an attempt was made to carry out oxidative dehydrogenation using an isotope oxygen trace method in the gas phase. Therefore, when CH3OH was converted to CO2 and dehydrogenated to HCOOCH3, the C-O bonds were not dissociated.

  10. Dehydrogenation of liquid fuel in microchannel catalytic reactor

    Science.gov (United States)

    Toseland, Bernard Allen; Pez, Guido Peter; Puri, Pushpinder Singh

    2009-02-03

    The present invention is an improved process for the storage and delivery of hydrogen by the reversible hydrogenation/dehydrogenation of an organic compound wherein the organic compound is initially in its hydrogenated state. The improvement in the route to generating hydrogen is in the dehydrogenation step and recovery of the dehydrogenated organic compound resides in the following steps: introducing a hydrogenated organic compound to a microchannel reactor incorporating a dehydrogenation catalyst; effecting dehydrogenation of said hydrogenated organic compound under conditions whereby said hydrogenated organic compound is present as a liquid phase; generating a reaction product comprised of a liquid phase dehydrogenated organic compound and gaseous hydrogen; separating the liquid phase dehydrogenated organic compound from gaseous hydrogen; and, recovering the hydrogen and liquid phase dehydrogenated organic compound.

  11. On the biologic origin of C6-C10-dicarboxylic and C6-C10-omega-1-hydroxy monocarboxylic acids in human and rat with acyl-CoA dehydrogenation deficiencies: in vitro studies on the omega- and omega-1-oxidation of medium-chain (C6-C12) fatty acids in human and rat liver.

    Science.gov (United States)

    Gregersen, N; Mortensen, P B; Kølvraa, S

    1983-10-01

    C6-C10-dicarboxylic acid C6-C10-omega-1-hydroxy monocarboxylic acids were measured in postmitochondrial (10,000 g) fractions of rat liver after incubation with hexanoic, octanoic, and decanoic acids. In livers both from fed and starved rats, the proportion of decanoic acid converted to sebacic acid was high (approximately 25%) with only minor accumulation of the intermediate 10-hydroxy decanoic acid (1-2%). The conversion of octanoic and hexanoic acids to suberic and adipic acids, respectively, was low (less than 1%). The intermediate 8-hydroxy octanoic and 6-hydroxy hexanoic acids were also accumulated in very small amounts (less than 1%). It was concluded that cytochrome-P-450-mediated omega-hydroxylation was of decisive importance for the production rate of the dicarboxylic acids. Analysis of kinetic parameters of human and rat liver microsomal omega- and omega-1-hydroxylation of hexanoic, octanoic, decanoic, and dodecanoic acids gave the following results: in rats, the apparent Km values for the omega-hydroxylation for dodecanoic and decanoic acids are low, ie., 171 and 3.1 mumole/liter, respectively, whereas they are high for octanoic and hexanoic acids (8211 and 8822 mumole/liter, respectively). In two different humans, the corresponding Km values for dodecanoic, decanoic, octanoic, and hexanoic acids are 3.6-186, 522-247, 4861-3892, and 6825-10400 mumole/liter, respectively. Based on these results, it is argued that adipic and suberic acids found in urine from rats and humans with acyl-CoA dehydrogenation deficiencies are not biosynthesized by direct omega-oxidation of hexanoic and octanoic acids, but most probably by means of beta-oxidation of sebacic and dodecanedioic acids, produced by direct omega-oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

    KAUST Repository

    Al-ShaikhAli, Anaam H.

    2016-11-30

    of strongly chemisorbed intermediate originating from TOL. DFT calculation indicated that Zn metal prefers to occupy the step sites of Ni where unselective C–C bond breaking was considered to preferentially occur, explaining suppression of hydrogenolysis activity. Additionally, it confirmed that the H-deficient species at methyl position group (C6H5CH2) was stable on the surface, making its hydrogenation being rate determining step, consistent with positive order in H2 pressure on TOL formation rate. This may explain the conclusive role by H2 in facilitating desorption of the H-deficient surface species that was produced through further dehydrogenation of TOL.

  13. Thermodynamic aspects of dehydrogenation reactions on noble metal surfaces.

    Science.gov (United States)

    Svane, K L; Hammer, B

    2014-11-01

    The reaction free energy for dehydrogenation of phenol, aniline, thiophenol, benzoic acid, and 1,4-benzenediol on the close packed copper, silver, and gold surfaces has been studied by density functional theory calculations. Dehydrogenation of thiophenol is found to be favourable on all three surfaces while aniline does not dehydrogenate on any of them. For phenol, benzenediol and benzoic acid dehydrogenation is favourable on copper and silver only, following the general trend of an increasing reaction free energy when going form gold to silver to copper. This trend can be correlated with the changes in bond lengths within the molecule upon dehydrogenation. While copper is able to replace hydrogen, leaving small changes in the bond lengths of the aromatic ring, the metal-molecule bond is weaker for silver and gold, resulting in a partial loss of aromaticity. This difference in bond strength leads to pronounced differences in adsorption geometries upon multiple dehydrogenations.

  14. Transition metal catalysed ammonia-borane dehydrogenation in ionic liquids.

    Science.gov (United States)

    Wright, William R H; Berkeley, Emily R; Alden, L R; Baker, R Tom; Sneddon, Larry G

    2011-03-21

    Significant advantages result from combining the disparate hydrogen release pathways for ammonia-borane (AB) dehydrogenation using ionic liquids (ILs) and transition metal catalysts. With the RuCl(2)(PMe(3))(4) catalyst precursor, AB dehydrogenation selectivity and extent are maximized in an IL with a moderately coordinating ethylsulfate anion.

  15. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    DEFF Research Database (Denmark)

    Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

    2016-01-01

    We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from...

  16. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    DEFF Research Database (Denmark)

    Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

    2016-01-01

    We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from...

  17. Microchannel apparatus and methods of conducting catalyzed oxidative dehydrogenation

    Science.gov (United States)

    Tonkovich, Anna Lee; Yang, Bin; Perry, Steven T.; Mazanec, Terry; Arora, Ravi; Daly, Francis P.; Long, Richard; Yuschak, Thomas D.; Neagle, Paul W.; Glass, Amanda

    2011-08-16

    Methods of oxidative dehydrogenation are described. Surprisingly, Pd and Au alloys of Pt have been discovered to be superior for oxidative dehydrogenation in microchannels. Methods of forming these catalysts via an electroless plating methodology are also described. An apparatus design that minimizes heat transfer to the apparatus' exterior is also described.

  18. Catalytic dehydrogenation of light alkanes on metals and metal oxides

    NARCIS (Netherlands)

    Sattler, Jesper J H B|info:eu-repo/dai/nl/328235601; Ruiz-Martinez, Javier|info:eu-repo/dai/nl/341386405; Santillan-Jimenez, Eduardo|info:eu-repo/dai/nl/323171958; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2014-01-01

    A study is conducted to demonstrate catalytic dehydrogenation of light alkanes on metals and metal oxides. The study provides a complete overview of the materials used to catalyze this reaction, as dehydrogenation for the production of light olefins has become extremely relevant. Relevant factors,

  19. Iridium-catalyzed intermolecular dehydrogenative silylation of polycyclic aromatic compounds without directing groups.

    Science.gov (United States)

    Murai, Masahito; Takami, Keishi; Takai, Kazuhiko

    2015-03-16

    This study describes the iridium-catalyzed intermolecular dehydrogenative silylation of C(sp(2))-H bonds of polycyclic aromatic compounds without directing groups. The reaction produced various arylsilanes through both Si-H and C-H bond activation, with hydrogen as the sole byproduct. Reactivity was affected by the electronic nature of the aromatic compounds, and silylation of electron-deficient and polycyclic aromatic compounds proceeded efficiently. Site-selectivity was controlled predominantly by steric factors. Therefore, the current functionalization proceeded with opposite chemo- and site-selectivity compared to that observed for general electrophilic functionalization of aromatic compounds.

  20. Dehydrogenation of ammonia borane in fluoro alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Kalidindi, Suresh Babu; Nethaji, Munirathinam; Jagirdar, Balaji R. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India)

    2010-10-15

    Dehydrogenation of ammonia borane was carried out in fluoro alcohol solvent in order to obtain compounds that are more likely candidates suitable for regeneration. Even though ammonia borane undergoes self-dissociation in 2,2,2-trifluoroethanol to liberate H{sub 2}, decent hydrogen release rates were obtained by using Co-Co{sub 2}B, Ni-Ni{sub 3}B, and Co-Ni-B nanocomposites as catalysts. These catalysts are magnetic in nature and hence can be separated from the reaction mixture using a magnet for re-use. The final by-product NH{sub 4}{sup +} B(OCH{sub 2}CF{sub 3}){sub 4}{sup -} obtained after the catalytic dehydrogenation of ammonia borane was thoroughly characterized using {sup 1}H, {sup 11}B, and {sup 13}C NMR and IR spectroscopies. The FTIR data showed that the B-O bond in NH{sub 4}{sup +} B(OCH{sub 2}CF{sub 3}){sub 4}{sup -} is slightly weaker compared to boric acid. Preliminary investigations on the regenerative routes for ammonia borane from the by-product NH{sub 4}{sup +} B(OCH{sub 2}CF{sub 3}){sub 4}{sup -} showed indications of the formation of BNH{sub x} species. (author)

  1. Production of pure hydrogen by ethanol dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples ' ' Federico II' ' Univ. (Italy). Dept. of Chemistry

    2010-12-30

    Hydrogen production from bio-ethanol is one of the most promising renewable processes to generate electricity using fuel cells. In this work, we have studied the production of pure hydrogen as by product of ethanol dehydrogenation reaction. This reaction is promoted by copper based catalysts and according to the catalyst used and the operative conditions gives place to acetaldehyde or ethyl acetate as main products. We studied in particular the performance of a commercial copper/copper chromite catalyst, supported on alumina and containing barium chromate as promoter that has given the best results. By operating at low pressure and temperature with short residence times, acetaldehyde is more selectively produced, while, by increasing the pressure (10-30 bars), the temperature (200-260 C) and the residence time (about 100 (grams hour/mol) of ethanol contact time) the selectivity is shifted to the production of ethyl acetate. However, in both cases pure hydrogen is obtained, as by product, that can easily be separated. Hydrogen obtained in this way is exempt of CO and can be directly fed to fuel cells without any inconvenience. In this work, runs performed in different operative conditions have been reported with the scope to individuate the best conditions. A carrier of H{sub 2} 6% in N{sub 2} has been used. The studied catalyst has also shown a good thermal stability with respect to sintering phenomena, that generally occurs during the dehydrogenation on other copper catalysts. Hydrogen productivities of 8-39 mol{sub H2} (gcat){sup -1}(h){sup -1} have been obtained for the explored temperature range 200-260 C. At last, the most accredited reaction mechanism is reported and discussed on the basis of the obtained results. (orig.)

  2. Tailored ceria nanoparticles for CO2 mediated ethylbenzene dehydrogenation

    NARCIS (Netherlands)

    Kovacevic, M.

    2016-01-01

    Styrene production via ethylbenzene dehydrogenation (EBDH) is one of the ten most important petrochemical processes. Possessing highly reactive double bond which facilitates self-polymerization and polymerization with other monomers, styrene is the fourth utmost essential bulk monomer at present.

  3. Adsorption and dehydrogenation of tetrahydroxybenzene on Cu(111)

    DEFF Research Database (Denmark)

    Bebensee, Fabian; Svane, K.; Bombis, Christian

    2013-01-01

    Adsorption of tetrahydroxybenzene (THB) on Cu(111) and Au(111) surfaces is studied using a combination of STM, XPS, and DFT. THB is deposited intact, but on Cu(111) it undergoes gradual dehydrogenation of the hydroxyl groups as a function of substrate temperature, yielding a pure dihydroxy......-benzoquinone phase at 370 K. Subtle changes to the adsorption structure upon dehydrogenation are explained from differences in molecule–surface bonding....

  4. Disruption of the acyl-coa binding protein gene delays hepatic adaptation to metabolic changes at weaning

    DEFF Research Database (Denmark)

    Neess, Ditte; Bloksgaard, Maria; Sørensen, Signe Bek;

    2011-01-01

    , little is known about the in vivo function in mammalian cells. We have generated mice with targeted disruption of ACBP (ACBP-/-). These mice are viable and fertile and develop normally. However, around weaning the ACBP-/- mice go through a crisis with overall weakness, and a slightly decreased growth...... rate. Using microarray analysis we show that the liver of ACBP-/- mice display a significantly delayed adaptation to weaning with late induction of target genes of the sterol regulatory element binding protein (SREBP) family. As a result, hepatic de novo cholesterogenesis is decreased at weaning....... The delayed induction of SREBP target genes around weaning is caused by a compromised processing and decreased expression of SREBP precursors leading to reduced binding of SREBP to target sites in chromatin. In conclusion, lack of ACBP interferes with the normal metabolic adaptation to weaning and leads...

  5. Dehydrogenation of polycyclic aromatic hydrocarbons in the diffuse interstellar medium

    CERN Document Server

    Foing, B H

    2000-01-01

    We present a model for the hydrogenation states of Polycyclic Aromatic Hydrocarbons (PAHs) in the diffuse interstellar medium. First, we study the abundance of hydrogenation and charge states of PAHs due to photo-ionization, photo-dissociation in the interstellar UV field, electron recombination and chemical reactions between PAH cations and H or H_2. For PAH cations, we find that the dehydrogenation effects are dominant. The hydrogenation state of PAHs depends strongly on the H density, the size of the molecule and UV field. In diffuse clouds with low H density and normal UV radiation, PAHs containing less than 40 C are completely or strongly dehydrogenated whereas at high H density, they are normally hydrogenated. The partially dehydrogenated species dominate in intermediate density clouds. PAHs above 40 C are quite stable and are fully hydrogenated, which would favor their spectroscopic search in near IR surveys of Diffuse Interstellar Bands (DIBs).

  6. Ruthenium-Catalyzed Ammonia Borane Dehydrogenation: Mechanism and Utility.

    Science.gov (United States)

    Zhang, Xingyue; Kam, Lisa; Trerise, Ryan; Williams, Travis J

    2017-01-17

    One of the greatest challenges in using H2 as a fuel source is finding a safe, efficient, and inexpensive method for its storage. Ammonia borane (AB) is a solid hydrogen storage material that has garnered attention for its high hydrogen weight density (19.6 wt %) and ease of handling and transport. Hydrogen release from ammonia borane is mediated by either hydrolysis, thus giving borate products that are difficult to rereduce, or direct dehydrogenation. Catalytic AB dehydrogenation has thus been a popular topic in recent years, motivated both by applications in hydrogen storage and main group synthetic chemistry. This Account is a complete description of work from our laboratory in ruthenium-catalyzed ammonia borane dehydrogenation over the last 6 years, beginning with the Shvo catalyst and resulting ultimately in the development of optimized, leading catalysts for efficient hydrogen release. We have studied AB dehydrogenation with Shvo's catalyst extensively and generated a detailed understanding of the role that borazine, a dehydrogenation product, plays in the reaction: it is a poison for both Shvo's catalyst and PEM fuel cells. Through independent syntheses of Shvo derivatives, we found a protective mechanism wherein catalyst deactivation by borazine is prevented by coordination of a ligand that might otherwise be a catalytic poison. These studies showed how a bidentate N-N ligand can transform the Shvo into a more reactive species for AB dehydrogenation that minimizes accumulation of borazine. Simultaneously, we designed novel ruthenium catalysts that contain a Lewis acidic boron to replace the Shvo -OH proton, thus offering more flexibility to optimize hydrogen release and take on more general problems in hydride abstraction. Our scorpionate-ligated ruthenium species (12) is a best-of-class catalyst for homogeneous dehydrogenation of ammonia borane in terms of its extent of hydrogen release (4.6 wt %), air tolerance, and reusability. Moreover, a synthetically

  7. Embedded silicene nanostructures in partly-dehydrogenated polysilane.

    Science.gov (United States)

    Li, Xiuling; Zeng, Xiao Cheng; Wu, Xiaojun

    2017-04-05

    Developing freestanding silicene nanostructures with tunable electronic and magnetic properties is of particular importance for their applications in nanoelectronics, but still faces big challenges. On the basis of first-principles calculations, here we predict that embedded silicene nanoflakes and nanoribbons can be realized by partly dehydrogenating a freestanding polysilane (Si6H6) sheet. Born-Oppenheimer molecular dynamics simulations indicate that the embedded silicene nanostructures show good thermal stability at 500 K. In particular, the embedded silicene nanostructures exhibit similar electronics properties to those of isolated ones. These findings imply a practical solution to produce embedded silicene nanostructures from partly dehydrogenated freestanding polysilane.

  8. Dehydrogenation of goethite in Earth’s deep lower mantle

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qingyang; Kim, Duck Young; Liu, Jin; Meng, Yue; Yang, Liuxiang; Zhang, Dongzhou; Mao, Wendy L.; Mao, Ho-kwang

    2017-01-31

    The cycling of hydrogen influences the structure, composition, and stratification of Earth’s interior. Our recent discovery of pyrite-structured iron peroxide (designated as the P phase) and the formation of the P phase from dehydrogenation of goethite FeO2H implies the separation of the oxygen and hydrogen cycles in the deep lower mantle beneath 1,800 km. Here we further characterize the residual hydrogen, x, in the P-phase FeO2Hx. Using a combination of theoretical simulations and high-pressure–temperature experiments, we calibrated the x dependence of molar volume of the P phase. Within the current range of experimental conditions, we observed a compositional range of P phase of 0.39 < x < 0.81, corresponding to 19–61% dehydrogenation. Increasing temperature and heating time will help release hydrogen and lower x, suggesting that dehydrogenation could be approaching completion at the high-temperature conditions of the lower mantle over extended geological time. Our observations indicate a fundamental change in the mode of hydrogen release from dehydration in the upper mantle to dehydrogenation in the deep lower mantle, thus differentiating the deep hydrogen and hydrous cycles.

  9. Transfer Methane to Fragrant Hydrocarbon by Direct Catalyzed Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Sponsored by NSFC,a research project -"Transfer methane to fragrant hydrocarbon by direct catalyzed dehydrogenation",directed by Prof.Xin Bao from Dalian Institute of Chemical Physics of CAS,honored the 2nd class National Science & Technology Award in 2005.

  10. Characterizing the infrared spectra of small, neutral, fully dehydrogenated PAHs

    CERN Document Server

    Mackie, C J; Bauschlicher, C W; Cami, J

    2014-01-01

    We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2$\\mu$m, 5.5$\\mu$m and 10.6$\\mu$m; at longer wavelengths, there is a forest of emission features in the 16--30$\\mu$m range that appears as a structured continuum, but with a clear peak cent...

  11. Propane Dehydrogenation on Metal and Metal Oxide Catalysts

    NARCIS (Netherlands)

    Sattler, Jesper

    2014-01-01

    In this PhD thesis, the catalytic performance and deactivation of various propane dehydrogenation catalysts is studied. First of all, a literature study is performed, where the three most commonly used formulations, namely Pt-, CrOx- and GaOx-based catalysts are compared in terms of yield relative t

  12. Combustion kinetics of the coke on deactivated dehydrogenation catalysts

    NARCIS (Netherlands)

    Luo, Sha; He, Songbo; Li, XianRu; Li, Jingqiu; Bi, Wenjun; Sun, Chenglin

    2015-01-01

    The coke combustion kinetics on the deactivated catalysts for long chain paraffin dehydrogenation was studied by the thermogravimetry and differential thermogravimetry (TG–DTG) technique. The amount and H/C mole ratio of the coke were determined by the TG and elemental analysis. And the comprehensiv

  13. Propane Dehydrogenation on Metal and Metal Oxide Catalysts

    NARCIS (Netherlands)

    Sattler, Jesper

    2014-01-01

    In this PhD thesis, the catalytic performance and deactivation of various propane dehydrogenation catalysts is studied. First of all, a literature study is performed, where the three most commonly used formulations, namely Pt-, CrOx- and GaOx-based catalysts are compared in terms of yield relative t

  14. Carbon mediated catalysis:A review on oxidative dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    De Chen; Anders Holmen; Zhijun Sui; Xinggui Zhou

    2014-01-01

    Carbon mediated catalysis has gained an increasing attention in both areas of nanocatalysis and nanomaterials. The progress in carbon nanomaterials provides many new opportunities to manip-ulate the types and properties of active sites of catalysts through manipulating structures, function-alities and properties of carbon surfaces. The present review focuses on progresses in carbon medi-ated oxidative dehydrogenation reactions of ethylbenzene, propane, and butane. The state-of-the-art of the developments of carbon mediated catalysis is discussed in terms of fundamental studies on adsorption of oxygen and hydrocarbons, reaction mechanism as well as effects of carbon nano-material structures and surface functional groups on the catalytic performance. We highlight the importance and challenges in tuning of the electron density of carbon and oxygen on carbon surfac-es for improving selectivity in oxidative dehydrogenation reactions.

  15. Kinetic modeling of ethylbenzene dehydrogenation over hydrotalcite catalysts

    KAUST Repository

    Atanda, Luqman

    2011-07-01

    Kinetics of ethylbenzene dehydrogenation to styrene was investigated over a series of quaternary mixed oxides of Mg3Fe0.25Me0.25Al0.5 (Me=Co, Mn and Ni) catalysts prepared by calcination of hydrotalcite-like compounds and compared with commercial catalyst. The study was carried out in the absence of steam using a riser simulator at 400, 450, 500 and 550°C for reaction times of 5, 10, 15 and 20s. Mg3Fe0.25Mn0.25Al0.5 afforded the highest ethylbenzene conversion of 19.7% at 550°C. Kinetic parameters for the dehydrogenation process were determined using the catalyst deactivation function based on reactant conversion model. The apparent activation energies for styrene production were found to decrease as follows: E1-Ni>E1-Co>E1-Mn. © 2011 Elsevier B.V.

  16. Hydrogen Production by Homogeneous Catalysis: Alcohol Acceptorless Dehydrogenation

    DEFF Research Database (Denmark)

    Nielsen, Martin

    2015-01-01

    in hydrogen production from biomass using homogeneous catalysis. Homogeneous catalysis has the advance of generally performing transformations at much milder conditions than traditional heterogeneous catalysis, and hence it constitutes a promising tool for future applications for a sustainable energy sector......, and are fundamental for the thrive of almost all business fields. The latter include the industries of agriculture, food additives, pharmaceuticals, electronics, plastic, fragrances, and more. Today, the major source of both energy and bulk chemicals is fossil fuels, being responsible for more than 80 % of the energy...... dehydrogenation. The third chapter, Biorelevant Substrates, concentrates on the use of alcohols such as ethanol, which are biomass related. The topic is alcohol acceptorless dehydrogenation reactions for both H2 production and the concurrent synthetic application. Finally, Chap. 4, Substrates for H2 Storage...

  17. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    Directory of Open Access Journals (Sweden)

    Rasmus Bjerregaard Christensen

    2016-01-01

    Full Text Available We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces.

  18. Dehydrogenation of Light Alkanes over Supported Pt Catalysts

    OpenAIRE

    Wu, Jason

    2015-01-01

    The production of light alkenes comprises a 250 million ton per year industry due to their extensive use in the production of plastics, rubbers, fuel blending agents, and chemical intermediates. While steam cracking and fluid catalytic cracking of petroleum crude oils are the most common methods for obtaining light alkenes, rising oil prices and low selectivities toward specific alkenes have driven the search for a more economical and efficient process. Catalytic dehydrogenation of light alka...

  19. Effect of alloying on carbon formation during ethane dehydrogenation

    DEFF Research Database (Denmark)

    Rovik, Anne; Kegnæs, Søren; Dahl, Søren

    2009-01-01

    The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested in the c......The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested...... in the conversion of ethane. A tendency is clear for all catalysts: In the first period of time 100% ethane is converted and roughly half of the carbon is converted into coke and deposited on the catalyst. The other half of the carbon is converted into methane. The active sites in the hydrogenolysis are blocked...... by coke during the initial period where after dehydrogenation of ethane is observed. It has previously been predicted in surface science studies that Ag covers the steps of certain transition metals. Here it is documented that the hydrogenolysis and coking reactions are significantly suppressed by co...

  20. Dehydrogenation kinetics and reversibility of LiAlH4-LiBH4 doped with Ti-based additives and MWCNT

    Science.gov (United States)

    Thaweelap, Natthaporn; Utke, Rapee

    2016-11-01

    Dehydrogenation kinetics and reversibility of LiAlH4-LiBH4 doped with Ti-based additives (TiCl3 and Ti-isopropoxide), multiwall carbon nanotubes (MWCNT), and MWCNT impregnated with Ti-based additives are proposed. Reduction of dehydrogenation temperature as well as improvements of kinetics and reversibility, especially decomposition of thermodynamically stable hydride (LiBH4) is obtained from the samples doped with Ti-isopropoxide and MWCNT. This can be due to the fact that the formations of LixAl(1-x)B2 and LiH-Al containing phase during dehydrogenation favor decomposition of LiH, leading to increment of hydrogen capacity, and stabilization of boron in solid state, resulting in improvement of reversibility. Besides, the curvatures and thermal conductivity of MWCNT benefit hydrogen diffusion and heat transfer during de/rehydrogenation. Nevertheless, deficient hydrogen content reversible is observed in all samples due to the irreversible of LiAlH4 and/or Li3AlH6 as well as the formation of stable phase (Li2B12H12) during de/rehydrogenation.

  1. Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

    Institute of Scientific and Technical Information of China (English)

    Masoud Hasany; Mohammad Malakootikhah; Vahid Rahmanian; Soheila Yaghmaei

    2015-01-01

    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.

  2. Structures of the dehydrogenation products of methane activation by 5d transition metal cations

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Redlich, B.; van der Meer, A. F. G.; Oomens, J.; Bakker, J. M.; Sweeney, A.; Mookherjee, A.; Armentrout, P. B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M +) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H]+ and H2. However, the structure of the dehydrogenation

  3. Structures of the dehydrogenation products of methane activation by 5d transition metal cations

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Redlich, B.; van der Meer, A. F. G.; Oomens, J.; Bakker, J. M.; Sweeney, A.; Mookherjee, A.; Armentrout, P. B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M +) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H]+ and H2. However, the structure of the dehydrogenation

  4. Photocatalytic acceptorless alkane dehydrogenation: scope, mechanism, and conquering deactivation with carbon dioxide.

    Science.gov (United States)

    Chowdhury, Abhishek Dutta; Julis, Jennifer; Grabow, Kathleen; Hannebauer, Bernd; Bentrup, Ursula; Adam, Martin; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2015-01-01

    Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make use of heterogeneous catalysts, which suffer from harsh reaction conditions and a lack of selectivity, whereas homogeneous methodologies rely mostly on unsolicited waste generation from hydrogen acceptors. Conversely, acceptorless photochemical alkane dehydrogenation in the presence of trans-Rh(PMe3 )2 (CO)Cl can be regarded as a more benign and atom efficient alternative. However, this methodology suffers from catalyst deactivation over time. Herein, we provide a detailed investigation of the trans-Rh(PMe3 )2 (CO)Cl-photocatalyzed alkane dehydrogenation using spectroscopic and theoretical investigations. These studies inspired us to utilize CO2 to prevent catalyst deactivation, which leads eventually to improved catalyst turnover numbers in the dehydrogenation of alkanes that include liquid organic hydrogen carriers.

  5. Propane Dehydrogenation over a Commercial Pt-Sn/Al2O3 Catalyst for Isobutane Dehydrogenation: Optimization of Reaction Conditions

    Institute of Scientific and Technical Information of China (English)

    Farnaz Tahriri Zangeneh; Saeed Sahebdelfar; Mohsen Bahmani

    2013-01-01

    The applicability of a commercial Pt-Sn/Al2O3 isobutane dehydrogenation catalyst in dehydrogenation of propane was studied.Catalyst performance tests were carried out in a fixed-bed quartz reactor under different operating conditions.Generally,as the factors improving propane conversion decrease the propylene selectivity,the optimal operating condition to maximize propylene yield is expected.The optimal condition was obtained by the experimental design method.The investigated parameters were temperature,hydrogen/hydrocarbon (H2/HC) ratio and space velocity,being changed in three levels.Constrains such as the susceptibility of the catalyst components to sintering or phase transformation were also taken into account.Activity,selectivity and stability of the catalyst were considered as the measured response factors,while the space-time-yield (STY) was considered as the variable to be optimized due to its commercial interest.A STY of 16 mol·kg-1·h-1 was achieved under the optimal conditions of T=620 ℃,H2/HC =0.6 and,weight hourly space velocity (WHSV) =2.2 h-1.Single carbon-carbon bond rupture was found to be the main route for the formation of lower hydrocarbon byproducts.

  6. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  7. An efficient strategy for designing ambipolar organic semiconductor material: Introducing dehydrogenated phosphorus atoms into pentacene core

    Science.gov (United States)

    Tang, Xiao-Dan

    2017-09-01

    The charge transport properties of phosphapentacene (P-PEN) derivatives were systematically explored by theoretical calculation. The dehydrogenated P-PENs have reasonable frontier molecular orbital energy levels to facilitate both electron and hole injection. The reduced reorganization energies of dehydrogenated P-PENs could be intimately connected to the bonding nature of phosphorus atoms. From the idea of homology modeling, the crystal structure of TIPSE-4P-2p is constructed and fully optimized. Fascinatingly, TIPSE-4P-2p shows the intrinsic property of ambipolar transport in both hopping and band models. Thus, introducing dehydrogenated phosphorus atoms into pentacene core could be an efficient strategy for designing ambipolar material.

  8. Kinetics with deactivation of methylcyclohexane dehydrogenation for hydrogen energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Maria, G.; Marin, A.; Wyss, C.; Mueller, S.; Newson, E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The methylcyclohexane dehydrogenation step to recycle toluene and release hydrogen is being studied as part of a hydrogen energy storage project. The reaction is performed catalytically in a fixed bed reactor, and the efficiency of this step significantly determines overall system economics. The fresh catalyst kinetics and the deactivation of the catalyst by coke play an important role in the process analysis. The main reaction kinetics were determined from isothermal experiments using a parameter sensitivity analysis for model discrimination. An activation energy for the main reaction of 220{+-}11 kJ/mol was obtained from a two-parameter model. From non-isothermal deactivation in PC-controlled integral reactors, an activation energy for deactivation of 160 kJ/mol was estimated. A model for catalyst coke content of 3-17 weight% was compared with experimental data. (author) 3 figs., 6 refs.

  9. PNP pincer osmium polyhydrides for catalytic dehydrogenation of primary alcohols.

    Science.gov (United States)

    Bertoli, Marcello; Choualeb, Aldjia; Gusev, Dmitry G; Lough, Alan J; Major, Quinn; Moore, Brandon

    2011-09-21

    This paper reports the synthesis, structure, and properties of a series of PNP pincer complexes of osmium OsH(3)Cl[HN(C(2)H(4)P(i)Pr(2))(2)] (1), OsH(3)[N(C(2)H(4)P(i)Pr(2))(2)] (2), OsH(4)[HN(C(2)H(4)P(i)Pr(2))(2)] (3), and OsH(2)(PMe(3))[HN(C(2)H(4)P(i)Pr(2))(2)] (4). The tetrahydride 3 operates as an efficient catalyst at 0.1 mol% loading for the reactions of amination and dehydrogenative coupling of primary alcohols, producing secondary amines and symmetrical esters, respectively. The catalyst 3 is distinguished by outstanding stability, and it can be used in an aqueous environment at temperatures as high as 200 °C.

  10. Spectroscopic evidence for origins of size and support effects on selectivity of Cu nanoparticle dehydrogenation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Witzke, M. E.; Dietrich, P. J.; Ibrahim, M. Y. S.; Al-Bardan, K.; Triezenberg, M. D.; Flaherty, D. W.

    2016-12-12

    Selective dehydrogenation catalysts that produce acetaldehyde from bio-derived ethanol can increase the efficiency of subsequent processes such as C–C coupling over metal oxides to produce 1-butanol or 1,3-butadiene or oxidation to acetic acid. Here, we use in situ X-ray absorption spectroscopy and steady state kinetics experiments to identify Cuδ+ at the perimeter of supported Cu clusters as the active site for esterification and Cu0 surface sites as sites for dehydrogenation. Correlation of dehydrogenation and esterification selectivities to in situ measures of Cu oxidation states show that this relationship holds for Cu clusters over a wide-range of diameters (2–35 nm) and catalyst supports and reveals that dehydrogenation selectivities may be controlled by manipulating either.

  11. Regioselective acceptorless dehydrogenative coupling of N-heterocycles toward functionalized quinolines, phenanthrolines, and indoles.

    Science.gov (United States)

    Talwar, Dinesh; Gonzalez-de-Castro, Angela; Li, Ho Yin; Xiao, Jianliang

    2015-04-20

    A new strategy has been developed for the oxidant- and base-free dehydrogenative coupling of N-heterocycles at mild conditions. Under the action of an iridium catalyst, N-heterocycles undergo multiple sp(3) CH activation steps, generating a nucleophilic enamine that reacts in situ with various electrophiles to give highly functionalized products. The dehydrogenative coupling can be cascaded with Friedel-Crafts addition, resulting in a double functionalization of the N-heterocycles.

  12. Water co-catalyzed selective dehydrogenation of methanol to formaldehyde and hydrogen

    Science.gov (United States)

    Shan, Junjun; Lucci, Felicia R.; Liu, Jilei; El-Soda, Mostafa; Marcinkowski, Matthew D.; Allard, Lawrence F.; Sykes, E. Charles H.; Flytzani-Stephanopoulos, Maria

    2016-08-01

    The non-oxidative dehydrogenation of methanol to formaldehyde is considered a promising method to produce formaldehyde and clean hydrogen gas. Although Cu-based catalysts have an excellent catalytic activity in the oxidative dehydrogenation of methanol, metallic Cu is commonly believed to be unreactive for the dehydrogenation of methanol in the absence of oxygen adatoms or oxidized copper. Herein we show that metallic Cu can catalyze the dehydrogenation of methanol in the absence of oxygen adatoms by using water as a co-catalyst both under realistic reaction conditions using silica-supported PtCu nanoparticles in a flow reactor system at temperatures below 250 °C, and in ultra-high vacuum using model PtCu(111) catalysts. Adding small amounts of isolated Pt atoms into the Cu surface to form PtCu single atom alloys (SAAs) greatly enhances the dehydrogenation activity of Cu. Under the same reaction conditions, the yields of formaldehyde from PtCu SAA nanoparticles are more than one order of magnitude higher than on the Cu nanoparticles, indicating a significant promotional effect of individual, isolated Pt atoms. Moreover, this study also shows the unexpected role of water in the activation of methanol. Water, a catalyst for methanol dehydrogenation at low temperatures, becomes a reactant in the methanol steam reforming reactions only at higher temperatures over the same metal catalyst.

  13. A visible light photocatalytic cross-dehydrogenative coupling/dehydrogenation/6π-cyclization/oxidation cascade: synthesis of 12-nitroindoloisoquinolines from 2-aryltetrahydroisoquinolines.

    Science.gov (United States)

    Rusch, Fabian; Unkel, Lisa-Natascha; Alpers, Dirk; Hoffmann, Frank; Brasholz, Malte

    2015-06-01

    A visible light-induced photocatalytic dehydrogenation/6π-cyclization/oxidation cascade converts 1-(nitromethyl)-2-aryl-1,2,3,4-tetrahydroisoquinolines into novel 12-nitro-substituted tetracyclic indolo[2,1-a]isoquinoline derivatives. Various photocatalysts promote the reaction in the presence of air and a base, the most efficient being 1-aminoanthraquinone in combination with K3 PO4 . Further, the 12-nitroindoloisoquinoline products can be accessed directly from C1-unfunctionalized 2-aryl-1,2,3,4-tetrahydroisoquinolines by extending the one-pot protocol with a foregoing photocatalytic cross-dehydrogenative coupling reaction, resulting in a quadruple cascade transformation.

  14. Process for alkane group dehydrogenation with organometallic catalyst

    Science.gov (United States)

    Kaska, William C.; Jensen, Craig M.

    1998-01-01

    An improved process is described for the catalytic dehydrogenation of organic molecules having a ##STR1## group to produce a ##STR2## group. The organic molecules are: ##STR3## wherein: A.sup.1, A.sup.2, A.sup.3, and A.sup.4 are each independently P, As or N: E.sup.2 is independently C or N; E.sup.3 is independently C, Si or Ge; E.sup.4 is independently C, Si, or Ge; and E.sup.5 is independently C, Si or Ge; M.sup.1, M.sup.2, M.sup.3, and M.sup.4 each is a metal atom independently selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium and platinum; Q.sup.1, Q.sup.2, Q.sup.3, and Q.sup.4 are each independently a direct bond, --CH.sub.2 --, --CH.sub.2 CH.sub.2 --, or CH.dbd.CH--; in structure I, structure II or structure IV, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are each independently selected from alkyl, alkenyl, cycloalkyl, and aryl, or R.sup.1 and R.sup.2 together and R.sup.3 and R.sup.4 together form a ring structure having from 4 to 10 carbon atoms, or in structure III, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are each independently selected from alkyl, alkenyl, cycloalkyl, and aryl, or R.sup.5 and R.sup.6 together and R.sup.7 and R.sup.8 together form a ring structure having from 4 to 10 carbon atoms, at a temperature of between about 100.degree. and 250.degree. C. for between about 1 hr and 300 days in the absence of N.sub.2. The surprisingly stable catalyst is a complex of an organic ligand comprising H, C, Si, N, P atoms, and a platinum group metal. The dehydrogenation is performed between about 100 to 200.degree. C., and has increased turnover.

  15. Arabidopsis CER8 encodes LONG-CHAIN ACYL-COA SYNTHETASE 1 (LACS1) that has overlapping functions with LACS2 in plant wax and cutin synthesis.

    Science.gov (United States)

    Lü, Shiyou; Song, Tao; Kosma, Dylan K; Parsons, Eugene P; Rowland, Owen; Jenks, Matthew A

    2009-08-01

    Plant cuticle is an extracellular lipid-based matrix of cutin and waxes, which covers aerial organs and protects them from many forms of environmental stress. We report here the characterization of CER8/LACS1, one of nine Arabidopsis long-chain acyl-CoA synthetases thought to activate acyl chains. Mutations in LACS1 reduced the amount of wax in all chemical classes on the stem and leaf, except in the very long-chain fatty acid (VLCFA) class wherein acids longer than 24 carbons (C(24)) were elevated more than 155%. The C(16) cutin monomers on lacs1 were reduced by 37% and 22%, whereas the C(18) monomers were increased by 28% and 20% on stem and leaf, respectively. Amounts of wax and cutin on a lacs1-1 lacs2-3 double mutant were much lower than on either parent, and lacs1-1 lacs2-3 had much higher cuticular permeability than either parent. These additive effects indicate that LACS1 and LACS2 have overlapping functions in both wax and cutin synthesis. We demonstrated that LACS1 has synthetase activity for VLCFAs C(20)-C(30), with highest activity for C(30) acids. LACS1 thus appears to function as a very long-chain acyl-CoA synthetase in wax metabolism. Since C(16) but not C(18) cutin monomers are reduced in lacs1, and C(16) acids are the next most preferred acid (behind C(30)) by LACS1 in our assays, LACS1 also appears to be important for the incorporation of C(16) monomers into cutin polyester. As such, LACS1 defines a functionally novel acyl-CoA synthetase that preferentially modifies both VLCFAs for wax synthesis and long-chain (C(16)) fatty acids for cutin synthesis.

  16. Moessbauer spectra of ferrite catalysts used in oxidative dehydrogenation

    Science.gov (United States)

    Cares, W. R.; Hightower, J. W.

    1971-01-01

    Room temperature Mossbauer spectroscopy was used to examine bulk changes which occur in low surface area CoFe2O4 and CuFe2O4 catalysts as a result of contact with various mixtures of trans-2-butene and O2 during oxidative dehydrogenation reactions at about 420 C. So long as there was at least some O2 in the gas phase, the CoFe2O4 spectrum was essentially unchanged. However, the spectrum changed from a random spinel in the oxidized state to an inverse spinel as it was reduced by oxide ion removal. The steady state catalyst lies very near the fully oxidized state. More dramatic solid state changes occurred as the CuFe2O4 underwent reduction. Under severe reduction, the ferrite was transformed into Cu and Fe3O4, but it could be reversibly recovered by oxidation. An intense doublet located near zero velocity persisted in all spectra of CuFe2O4 regardless of the state of reduction.

  17. Coverage- and temperature-dependent metalation and dehydrogenation of tetraphenylporphyrin on Cu(111).

    Science.gov (United States)

    Röckert, Michael; Franke, Matthias; Tariq, Quratulain; Ditze, Stefanie; Stark, Michael; Uffinger, Patrick; Wechsler, Daniel; Singh, Upendra; Xiao, Jie; Marbach, Hubertus; Steinrück, Hans-Peter; Lytken, Ole

    2014-07-14

    Using temperature-programmed desorption, supported by X-ray photoelectron spectroscopy and scanning tunneling microscopy, a comprehensive overview of the main reactions of 5,10,15,20-tetraphenyl-21H,23H-porphyrin (2HTPP) on Cu(111) as a function of coverage and temperature is obtained. Three reactions were identified: metalation with Cu substrate atoms, stepwise partial dehydrogenation, and finally complete dehydrogenation. At low coverage the reactions are independent of coverage, but at higher coverage metalation becomes faster and partial dehydrogenation slower. This behavior is explained by a weaker interaction between the iminic nitrogen atoms and the Cu(111) surface in the high-coverage checkerboard structure, leading to faster metalation, and the stabilizing effect of T-type interactions in the CuTPP islands formed at high coverage after metalation, leading to slower dehydrogenation. Based on the amount of hydrogen released and the appearance in STM, a structure of the partially dehydrogenated molecule is suggested. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. A New Homogeneous Catalyst for the Dehydrogenation of Dimethylamine Borane Starting with Ruthenium(III Acetylacetonate

    Directory of Open Access Journals (Sweden)

    Ebru Ünel Barın

    2015-06-01

    Full Text Available The catalytic activity of ruthenium(III acetylacetonate was investigated for the first time in the dehydrogenation of dimethylamine borane. During catalytic reaction, a new ruthenium(II species is formed in situ from the reduction of ruthenium(III and characterized using UV-Visible, Fourier transform infrared (FTIR, 1H NMR, and mass spectroscopy. The most likely structure suggested for the ruthenium(II species is mer-[Ru(N2Me43(acacH]. Mercury poisoning experiment indicates that the catalytic dehydrogenation of dimethylamine-borane is homogeneous catalysis. The kinetics of the catalytic dehydrogenation of dimethylamine borane starting with Ru(acac3 were studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Evaluation of the kinetic data provides the activation parameters for the dehydrogenation reaction: the activation energy Ea = 85 ± 2 kJ·mol−1, the enthalpy of activation ∆H# = 82 ± 2 kJ·mol−1 and the entropy of activation; ∆S# = −85 ± 5 J·mol−1·K−1. The ruthenium(II catalyst formed from the reduction of ruthenium(III acetylacetonate provides 1700 turnovers over 100 hours in hydrogen generation from the dehydrogenation of dimethylamine borane before deactivation at 60 °C.

  19. Theoretical investigation of the selective dehydration and dehydrogenation of ethanol catalyzed by small molecules.

    Science.gov (United States)

    Wang, Yanqun; Tang, Yizhen; Shao, Youxiang

    2017-09-01

    Catalytic dehydration and dehydrogenation reactions of ethanol have been investigated systematically using the ab initio quantum chemistry methods The catalysts include water, hydrogen peroxide, formic acid, phosphoric acid, hydrogen fluoride, ammonia, and ethanol itself. Moreover, a few clusters of water and ethanol were considered to simulate the catalytic mechanisms in supercritical water and supercritical ethanol. The barriers for both dehydration and dehydrogenation can be reduced significantly in the presence of the catalysts. It is revealed that the selectivity of the catalytic dehydration and dehydrogenation depends on the acidity and basicity of the catalysts and the sizes of the clusters. The acidic catalyst prefers dehydration while the basic catalysts tend to promote dehydrogenation more effectively. The calculated water-dimer catalysis mechanism supports the experimental results of the selective oxidation of ethanol in the supercritical water. It is suggested that the solvent- and catalyst-free self-oxidation of the supercritical ethanol could be an important mechanism for the selective dehydrogenation of ethanol on the theoretical point of view. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Industrial development of long chain paraffin (n-C10-C13) dehydrogenation catalysts and the deactivation characterization

    NARCIS (Netherlands)

    He, Songbo; Wang, Bin; Dai, Xihai; Sun, Chenglin; Bai, Ziwu; Wang, Xiao; Guo, Qi

    2015-01-01

    Pt–Sn–K–Mg/Al2O3 catalysts for the dehydrogenation of long chain paraffins (n-C100–C130) were successfully developed and applied in the industry. The catalysts were tested on both the industrial side fixed bed reactor and the industrial PACOL dehydrogenation plant. The industrially deactivated Pt–Sn

  1. Dehydrogenation characteristics of MgnH2n (n = 1-32) nanoclusters: A first-principles DFT study

    Science.gov (United States)

    Banerjee, P.; Chandrakumar, K. R. S.; Das, G. P.

    2015-06-01

    Ground state structures and dehydrogenation characteristics of MgnH2n (n = 1-32) nanoclusters have been investigated using first principles DFT approach. Dehydrogenation temperature gets reduced compared to the bulk rutile phase of MgH2, indicating its favorable usage for hydrogen storage.

  2. Oxidative dehydrogenation of ethane to ethylene using vanadia based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Ailing; Kalevaru, V.N. [Univ. Rostock e.V., Rostock (Germany). Leibniz-Inst. fuer Katalyse; Humar, A.S.; Lingaiah, N.; Sai Prasad, P.S.; Martin, A. [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2011-07-01

    In this work, we describe the application of V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalysts for the oxidative dehydrogenation (ODH) of ethane to ethylene. A series of Nb{sub 2}O{sub 5} supported V{sub 2}O{sub 5} catalysts were prepared by impregnation technique. NH{sub 4}VO{sub 3} was used as a precursor for V{sub 2}O{sub 5}. The content of V{sub 2}O{sub 5} is varied in the range from 5 to 20 wt%. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 500 to 600 C. The conversion of ethane has been increased from ca. 20 to 35 % with increase in temperature from 500 to 600 C, while the yield of ethylene is increased from about 5 to 12 % only. CO and CO{sub 2} are the only major by-products of the reaction. The activity tests were performed at low O{sub 2} concentration in the feed and hence low conversions were achieved. Furthermore, the conversion of ethane is found to increase continuously with increase in V{sub 2}O{sub 5} loading while the yield of C{sub 2}H{sub 4} increased only up to 10wt% V{sub 2}O{sub 5} and then decreased. Results revealed that the catalytic activity and selectivity is found to depend on the V{sub 2}O{sub 5} loading. Among all, 10wt% V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalyst has displayed the superior performance. (orig.)

  3. Oxidative dehydrogenation of ethane to ethylene using vanadia based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Ailing; Kalevaru, V.N. [Univ. Rostock e.V., Rostock (Germany). Leibniz-Inst. fuer Katalyse; Humar, A.S.; Lingaiah, N.; Sai Prasad, P.S.; Martin, A. [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2011-07-01

    In this work, we describe the application of V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalysts for the oxidative dehydrogenation (ODH) of ethane to ethylene. A series of Nb{sub 2}O{sub 5} supported V{sub 2}O{sub 5} catalysts were prepared by impregnation technique. NH{sub 4}VO{sub 3} was used as a precursor for V{sub 2}O{sub 5}. The content of V{sub 2}O{sub 5} is varied in the range from 5 to 20 wt%. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 500 to 600 C. The conversion of ethane has been increased from ca. 20 to 35 % with increase in temperature from 500 to 600 C, while the yield of ethylene is increased from about 5 to 12 % only. CO and CO{sub 2} are the only major by-products of the reaction. The activity tests were performed at low O{sub 2} concentration in the feed and hence low conversions were achieved. Furthermore, the conversion of ethane is found to increase continuously with increase in V{sub 2}O{sub 5} loading while the yield of C{sub 2}H{sub 4} increased only up to 10wt% V{sub 2}O{sub 5} and then decreased. Results revealed that the catalytic activity and selectivity is found to depend on the V{sub 2}O{sub 5} loading. Among all, 10wt% V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalyst has displayed the superior performance. (orig.)

  4. In situ Raman spectroscopy study of metal-enhanced hydrogenation and dehydrogenation of VO2

    Science.gov (United States)

    Wu, Hao; Fu, Qiang; Bao, Xinhe

    2016-11-01

    Vanadium dioxide (VO2) has a phase transition from insulator to metal at 340 K, and this transition can be strongly modified by hydrogenation. In this work, two dimensional (2D) VO2 sheets have been grown on Si(1 1 1) surfaces through chemical vapor deposition, and metal (Au, Pt) thin films were deposited on VO2 surfaces by sputtering. The hydrogenation and dehydrogenation of VO2 and metal-decorated VO2 structures in H2 and in air were in situ studied by Raman. We found that hydrogenation and dehydrogenation temperatures have been significantly decreased with the VO2 surface decorated by Au and Pt. The enhanced hydrogenation and dehydrogenation reactions can be attributed to catalytic dissociation of H2 and O2 molecules on metal surfaces and subsequent spillover of dissociated H and O atoms to the oxide surfaces.

  5. Uniform dehydrogenation of amorphous silicon thin films using a wide thermal annealing system

    Science.gov (United States)

    Jung, Yong Chan; Seong, Sejong; Lee, Taehoon; Ahn, Jinho; Kim, Tae Hyun; Yeo, Won-Jae; Park, In-Sung

    2017-02-01

    To prevent ablation caused by sudden hydrogen eruption during crystallization of hydrogenated amorphous Si (a-Si:H) thin films, a wide dehydrogenation thermal annealing (wDTA) system was developed to reduce hydrogen content in a-Si:H film prior to its crystallization process. The annealed a-Si:H films were fully dehydrogenated and nanocrystallized by the wDTA system. Raman scattering measurement revealed that the dehydrogenation process lowers the hydrogen content through disappearance of the peak intensity at 2000 cm-1. The a-Si:H film was transformed into nanocrystallized Si with lower residual stress. The major advantage of this wDTA was the large area uniformity of the thermal and the resulting material properties for 8 generation display. The uniform material characteristics of the hydrogen content, thickness, energy bandgap, and transmittance of the annealed Si films in the overall area was confirmed by Raman spectroscopy, spectroscopic ellipsometry, and UV-vis spectrometer measurement.

  6. Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals

    Science.gov (United States)

    Kislitsyn, Dmitry A.; Mills, Jon M.; Kocevski, Vancho; Chiu, Sheng-Kuei; DeBenedetti, William J. I.; Gervasi, Christian F.; Taber, Benjamen N.; Rosenfield, Ariel E.; Eriksson, Olle; Rusz, Ján; Goforth, Andrea M.; Nazin, George V.

    2016-06-01

    We present results of a scanning tunneling spectroscopy (STS) study of the impact of dehydrogenation on the electronic structures of hydrogen-passivated silicon nanocrystals (SiNCs) supported on the Au(111) surface. Gradual dehydrogenation is achieved by injecting high-energy electrons into individual SiNCs, which results, initially, in reduction of the electronic bandgap, and eventually produces midgap electronic states. We use theoretical calculations to show that the STS spectra of midgap states are consistent with the presence of silicon dangling bonds, which are found in different charge states. Our calculations also suggest that the observed initial reduction of the electronic bandgap is attributable to the SiNC surface reconstruction induced by conversion of surface dihydrides to monohydrides due to hydrogen desorption. Our results thus provide the first visualization of the SiNC electronic structure evolution induced by dehydrogenation and provide direct evidence for the existence of diverse dangling bond states on the SiNC surfaces.

  7. Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles.

    Science.gov (United States)

    Kojima, Masahiro; Kanai, Motomu

    2016-09-26

    Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.

  8. Theoretical investigation of the mechanism of tritiated methane dehydrogenation reaction using nickel-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Li, Jiamao; Deng, Bing; Yang, Yong; Wang, Heyi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Li, Shuo, E-mail: lishuo@cqut.edu.cn [School of Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Tan, Zhaoyi, E-mail: tanzhaoyi@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-06-15

    Graphical abstract: - Highlights: • Four-step dehydrogenation of CT{sub 4} catalyzed by Ni to form Ni–C by releasing T{sub 2}. • The process of Ni + CT{sub 4} → NiCT{sub 2} + T{sub 2} is more achievable than that of NiCT{sub 2} → NiC + T{sub 2}. • TNiCT → T{sub 2}NiC step is the RDS with the rate constant of k = 2.8 × 10{sup 13} exp(−313,136/RT). • The hydrogen isotope effect value of k{sub H}/k{sub T} is 2.94, and k{sub D}/k{sub T} is 1.39. • CH{sub 4} and CD{sub 4} dehydrogenations are likely to occur, accompanied by the CT{sub 4} cracking. - Abstract: The mechanism of tritiated methane dehydrogenation reaction catalyzed by nickel-based catalyst was investigated in detail by density functional theory (DFT) at the B3LYP/[6-311++G(d, p), SDD] level. The computational results indicated that the dehydrogenation of tritiated methane is endothermic. The decomposition of tritiated methane catalyzed by Ni to form Ni-based carbon (Ni–C) after a four-step dehydrogenation companied with releasing tritium. After the first and second dehydrogenation steps, Ni + CT{sub 4} formed NiCT{sub 2}. After the third and fourth dehydrogenation steps, NiCT{sub 2} formed NiC. The first and second steps of dehydrogenation occurred on both the singlet and triplet states, and the lowest energy route is Ni + CT{sub 4} → {sup 1}COM → {sup 1}TS1 → {sup 3}IM1 → {sup 3}TS2 → {sup 3}IM2. The third and fourth steps of dehydrogenation occurred on both the singlet and quintet states, and the minimum energy reaction pathway appeared to be IM3 → {sup 1}TS4 → {sup 5}IM4 → {sup 5}TS5 → {sup 5}IM5 → {sup 5}pro + T{sub 2}. The fourth step of dehydrogenation TNiCT → T{sub 2}NiC was the rate-determining step of the entire reaction with the rate constant of k{sub 2} = 2.8 × 10{sup 13} exp(−313,136/RT) (in cm{sup 3} mol{sup −1} s{sup −1}), and its activation energy barrier was calculated to be 51.8 kcal/mol. The Ni-catalyzed CH{sub 4} and CD{sub 4} cracking

  9. Hydrogenation/Dehydrogenation Performances of the MgH2-WS2 Composites

    Institute of Scientific and Technical Information of China (English)

    WANG Jiasheng; ZHANG Wei; CHENG Ying; KE Dandan; HAN Shumin

    2015-01-01

    The hydrogenation/dehydrogenation kinetics and thermodynamic behaviors of the MgH2-WS2 composites were investigated. The TPD (Temperature-Programmed-Desorption) curves showed that the onset dehydrogenation temperature of the MgH2 + 20wt% WS2 composite was 615 K, 58 K lower than that of the pristine MgH2. The kinetic measurements showed that within 21 min, the MgH2 + 20wt% WS2 composite could absorb 2.818wt% at 423 K, and release 4.244 wt% of hydrogen at 623 K, while the hydriding/dehydriding capacity of MgH2 reached only 0.979wt% and 2.319wt% respectively under identical conditions. The improvement of hydrogenation/dehydrogenation performances for the composite was attributed to the co-catalytic effect between the new phases W and MgS which formed during the ball-milling process.

  10. Manipulation of the electronic structure by reversible dehydrogenation of tetra(p-hydroxyphenyl)porphyrin molecules

    CERN Document Server

    Smykalla, Lars; Mende, Carola; Rüffer, Tobias; Lang, Heinrich; Hietschold, Michael

    2014-01-01

    The controlled and reversible interconversion between the free-base and the doubly dehydrogenated form of a 5,10,15,20-tetra(p-hydroxyphenyl)porphyrin molecule in an ordered array is demonstrated. This is achieved through voltage pulses by hydrogen transfer between the center of the porphyrin and the tip of a scanning tunneling microscope (STM). The local dehydrogenation leads to significant shifts in the energetic positions of the molecular orbitals. Density functional theory (DFT) calculations corroborate our conclusions and allow to gain more insight into the different energy level alignment before and after dehydrogenation. Due to the different conductance at a given voltage a clear distinction of both molecular species is possible, which also enables the application as a single-molecular switch.

  11. Aerobic dehydrogenation of cyclohexanone to cyclohexenone catalyzed by Pd(DMSO)2(TFA)2: evidence for ligand-controlled chemoselectivity.

    Science.gov (United States)

    Diao, Tianning; Pun, Doris; Stahl, Shannon S

    2013-06-05

    The dehydrogenation of cyclohexanones affords cyclohexenones or phenols via removal of 1 or 2 equiv of H2, respectively. We recently reported several Pd(II) catalyst systems that effect aerobic dehydrogenation of cyclohexanones with different product selectivities. Pd(DMSO)2(TFA)2 is unique in its high chemoselectivity for the conversion of cyclohexanones to cyclohexenones, without promoting subsequent dehydrogenation of cyclohexenones to phenols. Kinetic and mechanistic studies of these reactions reveal the key role of the dimethylsulfoxide (DMSO) ligand in controlling this chemoselectivity. DMSO has minimal kinetic influence on the rate of Pd(TFA)2-catalyzed dehydrogenation of cyclohexanone to cyclohexenone, while it strongly inhibits the second dehydrogenation step, conversion of cyclohexenone to phenol. These contrasting kinetic effects of DMSO provide the basis for chemoselective formation of cyclohexenones.

  12. Role of Ti doping and Al and B vacancies in the dehydrogenation of Al(BH₄)₃

    Indian Academy of Sciences (India)

    INDRANI CHOUDHURI; ARUP MAHATA; KUBER SINGH RAWAT; BISWARUP PATHAK

    2016-10-01

    Metal borohydrides such as Al(BH₄)₃ is thermodynamically very stable but has weak dehydrogenation property. In contrast, Ti(BH₄)₃ has less stability (25◦C) but excellent dehydrogenation property. Hence, we have studied Ti-doped aluminium borohydride systems in order to improve the dehydrogenation property. Our density functional studies (DOS and pDOS) show that Ti interacts more strongly with the BH₄ unit and such strong interaction weakens the B-H bond and improves the dehydrogenation property. Ti-doped Al(BH₄)₃ system improves the overall stability due to the formation of a stronger Ti-B bond. Our study on defects in Al(BH₄)₃ suggests that B-defect system has the best dehydrogenation property compared to the pure and Ti-doped Al(BH₄)₃ systems.

  13. Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille

    2015-01-01

    cycles. One carbon monoxide ligand was shown to remain coordinated to iridium throughout the reaction, and release of carbon monoxide was suggested to occur from a dicarbonyl complex. IrH2Cl(CO)(rac-BINAP) was also synthesized and detected in the dehydrogenation of benzyl alcohol. In the same experiment......The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving...

  14. Mechanistic insights into the oxidative dehydrogenation of amines to nitriles in continuous flow

    DEFF Research Database (Denmark)

    Corker, Emily C.; Ruiz-Martínez, Javier; Riisager, Anders;

    2015-01-01

    The oxidative dehydrogenation of various aliphatic amines to their corresponding nitrile compounds using RuO2/Al2O3 catalysts in air was successfully applied to a continuous flow reaction. Conversions of amines (up to >99%) and yields of nitriles (up to 77%) varied depending on reaction conditions...... and the amine utilised. The presence of water was found to be important for the activity and stability of the RuO2/Al2O3 catalyst. The Hammett relationship and in situ infrared spectroscopy were applied to divulge details about the catalytic mechanism of the oxidative dehydrogenation of amines over RuO2/Al2O3...

  15. Oxidative dehydrogenation of isobutane over supported V–Mo mixed oxides

    Directory of Open Access Journals (Sweden)

    IOAN-CEZAR MARCU

    2010-08-01

    Full Text Available Vanadium–molybdenum oxides supported on Al2O3, CeO2 and TiO2 were prepared by a “wet” impregnation method, characterized using XRD, N2 adsorption, UV–Vis spectroscopy, electrical conductivity measurements and tested in the oxidative dehydrogenation of isobutane. The catalytic performance in the oxidative dehydrogenation of isobutane at 400–550 °C depended on the nature of support and on the content of VMoO species on the support. The catalysts supported on alumina were more active and selective than those supported on ceria and titania.

  16. Dehydrogenative Aromatization of Saturated Aromatic Compounds by Graphite Oxide and Molecular Sieves

    Institute of Scientific and Technical Information of China (English)

    张轩; 徐亮; 王希涛; 马宁; 孙菲菲

    2012-01-01

    Graphite oxide (GO) has attracted much attention of material and catalysis chemists recently. Here we describe a combination of GO and molecular sieves for the dehydrogenative aromatization. GO prepared through improved Hummers method showed high oxidative activity in this reaction. Partially or fully saturated aromatic compounds were converted to their corresponding dehydrogenated aromatic products with fair to excellent conversions and selectivities. As both GO and molecular sieves are easily available, cheap, lowly toxic and have good tolerance to various functional groups, this reaction provides a facile approach toward aromatic compounds from their saturated precursors

  17. Studies on dehydrogenation of cyclohexanol to cyclohexanone over mesoporous SiO₂ supported copper catalysts

    Indian Academy of Sciences (India)

    B SRIDEVI; P NAGAIAH; A H PADMASRI; B DAVID RAJU; K S RAMA RAO

    2017-05-01

    SBA-15, KIT-6, SiO₂ supported catalysts with 10% Cu loading have been prepared by impregnation techniques. The prepared catalysts have been characterized by BET technique, X-ray diffraction, Temperature programmed reduction (TPR), XPS and N₂O pulse chemisorption techniques. Dehydrogenation of cyclohexanol has been performed over these catalysts in vapour phase at 523 K. SBA-15 and KIT-6 supported copper catalystsshowed higher activity than SiO₂ supported Cu catalyst in dehydrogenation of cyclohexanol, which can be attributed to better Cu dispersion, small copper particle size and more number of Cu active species presented on the surface of mesoporous supported catalysts.

  18. Iodine Deficiency

    Science.gov (United States)

    ... 2017 By ATA | Featured , Iodine Deficiency , News Releases , Potassium Iodide (KI) | No Comments IDD NEWSLETTER – February 2017 VOLUME ... 2016 By ATA | Featured , Iodine Deficiency , News Releases , Potassium Iodide (KI) | No Comments IDD NEWSLETTER – November 2015 (PDF ...

  19. Application of Heterogeneous Copper Catalyst in a Continuous Flow Process: Dehydrogenation of Cyclohexanol

    Science.gov (United States)

    Glin´ski, Marek; Ulkowska, Urszula; Iwanek, Ewa

    2016-01-01

    In this laboratory experiment, the synthesis of a supported solid catalyst (Cu/SiO2) and its application in the dehydrogenation of cyclohexanol performed under flow conditions was studied. The experiment was planned for a group of two or three students for two 6 h long sessions. The copper catalyst was synthesized using incipient wetness…

  20. Dehydrogenation of methanol on Pd(100): comparison with the results of Pd(111).

    Science.gov (United States)

    Jiang, Ruibin; Guo, Wenyue; Li, Ming; Lu, Xiaoqing; Yuan, Jianye; Shan, Honghong

    2010-07-28

    Dehydrogenation of methanol on Pd(100) is systematically investigated using self-consistent periodic density functional theory. The theoretical results are compared with those of the same reaction on Pd(111) published very recently [J. Phys. Chem. C, 2009, 113, 4188-4197]. Switching from (111) to (100), adsorptions are strengthened for most species except for CHO, CO and H at hollow sites. Moreover, Pd(100) affords relatively low energy barriers and higher rate constants for most elementary dehydrogenation steps as well as smaller desorption rates for the saturated adsorbates (methanol and formaldehyde), suggesting that the more open Pd surface indeed possesses the higher activity and selectivity for the complete dehydrogenation of methanol. At lower temperatures (e.g., 250 K), Pd(100) affords the same dehydrogenation path as Pd(111) for methanol, which is unchanged on the latter surface at both lower and higher temperatures; whereas at the typical steam re-forming (MSR) temperature (500 K), the path on Pd(100), i.e., CH(3)OH --> CH(3)O and/or CH(2)OH --> CH(2)O --> CHO --> CO, is different from the situation of Pd(111). In both cases, the initial bond scission process constitutes the rate-determining step.

  1. Iridium complexes of new NCP pincer ligands: catalytic alkane dehydrogenation and alkene isomerization.

    Science.gov (United States)

    Jia, Xiangqing; Zhang, Lei; Qin, Chuan; Leng, Xuebing; Huang, Zheng

    2014-09-28

    Iridium complexes of novel NCP pincer ligands containing pyridine and phosphinite arms have been synthesized. One Ir complex shows good catalytic activity for alkane dehydrogenation, and all complexes are highly active for olefin isomerization. A combination of the Ir complex and a (PNN)Fe pincer complex catalyzes the formation of linear alkylboronates selectively from internal olefins via sequential olefin isomerization-hydroboration.

  2. Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

    KAUST Repository

    Shaikh Ali, Anaam

    2015-07-06

    Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

  3. Dehydrogenation of light alkanes over rhenium catalysts on conventional and mesoporous MFI supports

    DEFF Research Database (Denmark)

    Rovik, Anne Krogh; Hagen, Anke; Schmidt, I.;

    2006-01-01

    Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing amounts of ethene were produced with time on s...

  4. Hydrogen peroxide modified Mg-Al-O oxides supported Pt-Sn catalysts for paraffin dehydrogenation

    NARCIS (Netherlands)

    Lai, Y.; He, Songbo; Luo, S.; Bi, W.; Li, XianRu; Sun, Chenglin; Seshan, Kulathuiyer

    2015-01-01

    In this work, a new method to prepare Mg–Al–O oxide by co-precipitation method with addition of H2O2 was developed. The application of Mg–Al–O as a support of Pt–Sn catalysts for paraffin dehydrogenation was investigated. Characterization results indicated that modification of H2O2 (i) enlarged the

  5. Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille;

    2015-01-01

    The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving dehyd...... a rate-determining phosphine dissociation for the decarbonylation of aldehydes....

  6. Copper oxide as efficient catalyst for oxidative dehydrogenation of alcohols with air

    DEFF Research Database (Denmark)

    Poreddy, Raju; Engelbrekt, Christian; Riisager, Anders

    2015-01-01

    The oxidative dehydrogenation of alcohols to carbonyl compounds was studied using CuO nanoparticle catalysts prepared by solution synthesis in buffered media. CuO nanoparticles synthesized in N-cyclohexyl- 3-aminopropanesulfonic acid buffer showed high catalytic activity for the oxidation...

  7. Oxidative dehydrogenation of ethylbenzene using nitrous oxide over vanadia-magnesia catalysts

    NARCIS (Netherlands)

    Shiju, N.R.; Anilkumar, M.; Gokhale, S.P.; Rao, B.S.; Satyanarayana, C.V.V.

    2011-01-01

    A series of V-Mg-O catalysts with different loadings of vanadia were prepared by the wet impregnation method and the effect of the local structure of these catalysts on the oxidative dehydrogenation of ethylbenzene with N2O was investigated. High styrene selectivity (97%) was obtained at 773 K. The

  8. Structures of the Dehydrogenation Products of Methane Activation by 5d Transition Metal Cations

    NARCIS (Netherlands)

    Lapoutre, V.J.F.; Redlich, B.; Meer, A.F.G.; Oomens, J.; Bakker, J.M.; Sweeney, A.; Mookherjee, A.; Armentrout, P.B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M+) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H](+) and H-2. However, the structure of the

  9. Palladium-catalyzed aerobic dehydrogenative aromatization of cyclohexanone imines to arylamines.

    Science.gov (United States)

    Hajra, Alakananda; Wei, Ye; Yoshikai, Naohiko

    2012-11-02

    Dehydrogenative aromatization of cyclohexanone imines to arylamines has been achieved using a palladium catalyst under aerobic conditions. The reaction is applicable to a variety of imines that are either preformed or generated in situ from cyclohexanone derivatives and aryl or alkylamines.

  10. Acceptorless Dehydrogenation of N-Heterocycles by Merging Visible-Light Photoredox Catalysis and Cobalt Catalysis.

    Science.gov (United States)

    He, Ke-Han; Tan, Fang-Fang; Zhou, Chao-Zheng; Zhou, Gui-Jiang; Yang, Xiao-Long; Li, Yang

    2017-03-06

    Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N-heterocycles, by merging visible-light photoredox catalysis and cobalt catalysis at ambient temperature, is described. The potential applications to organic transformations and hydrogen-storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.

  11. Iridium‐Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols with the Liberation of Syngas

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Madsen, Robert

    2012-01-01

    to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)–BINAP species. First, dehydrogenation...

  12. Cooperative dehydrogenation of N-heterocycles using a carbon nanotube-rhodium nanohybrid.

    Science.gov (United States)

    Jawale, Dhanaji V; Gravel, Edmond; Shah, Nimesh; Dauvois, Vincent; Li, Haiyan; Namboothiri, Irishi N N; Doris, Eric

    2015-05-04

    Rhodium nanoparticles were anchored on carbon nanotubes and the resulting nanohybrid was studied as co-catalyst, along with tert-butylcatechol, for the dehydrogenation of various N-heterocycles. The co-catalytic system operates in high yields, under the mildest conditions reported so far, and can be applied to a wide variety of secondary amine-containing scaffolds.

  13. Demonstration of a packed bed membrane reactor for the oxidative dehydrogenation of propane

    NARCIS (Netherlands)

    Kotanjac, Zeljko; van Sint Annaland, M.; Kuipers, J.A.M.

    2010-01-01

    An experimental demonstration of the oxidative dehydrogenation of propane (ODHP) in a lab-scale packed bed membrane reactor has been performed. Experiments were carried out with both premixed and distributed oxygen feed over a Ga2O3/MoO3 catalyst and compared, and the influence of the gas

  14. Simultaneous dehydrogenation of organic compounds and hydrogen removal by hydride forming alloys

    NARCIS (Netherlands)

    Appelman, W.J.T.M.; Kuczynski, M.; Versteeg, G.F.

    1992-01-01

    The applicability of hydrogen-absorbing metals in dehydrogenation reactions was investigated. Based on thermodynamic considerations, operating ranges were defined within which an increase of the reactant conversion can he achieved owing to an in situ hydrogen removal by the alloy. Low plateau pressu

  15. Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation

    DEFF Research Database (Denmark)

    Leth, Karen Thrane; Rovik, Anne Krogh; Holm, Martin Spangsberg

    2008-01-01

    difference being the morphology of the crystals. The catalytic properties of the samples were tested in ethane dehydrogenation at 823 K and at atmospheric pressure. The two Ga-MFI samples differ greatly in conversion of ethane, as a result of their difference in porosity, and it is found that the conversion...

  16. Unravelling The Mechanism of Basic Aqueous Methanol Dehydrogenation Catalyzed By Ru-PNP Pincer Complexes

    DEFF Research Database (Denmark)

    Alberico, Elisabetta; Lennox, Alastair J. J.; Vogt, Lydia K.;

    2016-01-01

    Ruthenium PNP complex 1a (RuH(CO)Cl(HN(C2H4Pi-Pr2)2)) represents a state-of-the-art catalyst for low-temperature (methanol dehydrogenation to H2 and CO2. Herein, we describe an investigation that combines experiment, spectroscopy, and theory to provide a mechanistic rationale...

  17. CHARACTERIZING THE INFRARED SPECTRA OF SMALL, NEUTRAL, FULLY DEHYDROGENATED POLYCYCLIC AROMATIC HYDROCARBONS

    Energy Technology Data Exchange (ETDEWEB)

    Mackie, C. J.; Peeters, E.; Cami, J. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Bauschlicher, C. W. Jr., E-mail: mackie@strw.leidenuniv.nl [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035 (United States)

    2015-02-01

    We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2 μm, 5.5 μm, and 10.6 μm; at longer wavelengths, there is a forest of emission features in the 16-30 μm range that appears as a structured continuum, but with a clear peak centered around 19 μm. We searched for these features in Spitzer-IRS spectra of various positions in the reflection nebula NGC 7023. We find a weak emission feature at 10.68 μm in all positions except that closest to the central star. We also find evidence for a weak 19 μm feature at all positions that is not likely due to C{sub 60}. We interpret these features as tentative evidence for the presence of a small population of fully dehydrogenated PAHs, and discuss our results in the framework of PAH photolysis and the formation of fullerenes.

  18. Spontaneous dehydrogenation of methanol over defect-free MgO(100) thin film deposited on molybdenum

    CERN Document Server

    Song, Zhenjun

    2016-01-01

    The dehydrogenation reaction of methanol on metal supported MgO(100) films has been studied by employing periodic density functional calculations. As far as we know, the dehydrogenation of single methanol molecule over inert oxide insulators such as MgO has never been realized before without the introduction of defects and low coordinated atoms. By depositing the very thin oxide films on Mo substrate we have successfully obtained the dissociative state of methanol. The dehydrogenation reaction is energetically exothermic and nearly barrierless. The metal supported thin oxide films studied here provide a versatile approach to enhance the activity and properties of oxides.

  19. Disaccharidase deficiency.

    Science.gov (United States)

    Bayless, T M; Christopher, N L

    1969-02-01

    This review of the literature and current knowledge concerning a nutritional disorder of disaccharidase deficiency discusses the following topics: 1) a description of disorders of disaccharide digestion; 2) some historical perspective on the laboratory and bedside advances in the past 10 years that have helped define a group of these digestive disorders; 3) a classification of conditions causing disaccharide intolerance; and 4) a discussion of some of the specific clinical syndromes emphasizing nutritional consequences of these syndromes. The syndromes described include congenital lactase deficiency, acquired lactase deficiency in teenagers and adults, acquired generalized disaccharidase deficiency secondary to diffuse mucosal damage, acquired lactose intolerance secondary to alterations in the intestinal transit, sucrase-isomaltase deficiencies, and other disease associations connected with lactase deficiency such as colitis.

  20. Theoretical Studies on Dehydrogenation Reactions in Mg2(BH4)2(NH2)2 Compounds

    Institute of Scientific and Technical Information of China (English)

    Zheng Chen; Zhe-ning Chen; An-an Wu; Guo-tao Wu; Zhi-tao Xiong; Ping Chen; Xin Xu

    2012-01-01

    Borohydrides have been recently hightlighted as prospective new materials due to their high gravimetric capacities for hydrogen storage.It is,therefore,important to understand the underlying dehydrogenation mechanisms for further development of these materials.We present a systematic theoretical investigation on the dehydrogenation mechanisms of the Mg2(BH4)2(NH2)2 compounds.We found that dehydrogenation takes place most likely via the intermolecular process,which is favorable both kinetically and thermodynamically in comparison with that of the intramolecular process.The dehydrogenation of Mg2(BH4)2(NH2)2 initially takes place via the direct combination of the hydridic H in BH4-and the protic H in NH2-,followed by the formation of Mg-H and subsequent ionic recombination of Mg-Hδ-… Hδ+-N.

  1. CO2 emission free co-generation of energy and ethylene in hydrocarbon SOFC reactors with a dehydrogenation anode.

    Science.gov (United States)

    Fu, Xian-Zhu; Lin, Jie-Yuan; Xu, Shihong; Luo, Jing-Li; Chuang, Karl T; Sanger, Alan R; Krzywicki, Andrzej

    2011-11-21

    A dehydrogenation anode is reported for hydrocarbon proton conducting solid oxide fuel cells (SOFCs). A Cu-Cr(2)O(3) nanocomposite is obtained from CuCrO(2) nanoparticles as an inexpensive, efficient, carbon deposition and sintering tolerant anode catalyst. A SOFC reactor is fabricated using a Cu-Cr(2)O(3) composite as a dehydrogenation anode and a doped barium cerate as a proton conducting electrolyte. The protonic membrane SOFC reactor can selectively convert ethane to valuable ethylene, and electricity is simultaneously generated in the electrochemical oxidative dehydrogenation process. While there are no CO(2) emissions, traces of CO are present in the anode exhaust when the SOFC reactor is operated at over 700 °C. A mechanism is proposed for ethane electro-catalytic dehydrogenation over the Cu-Cr(2)O(3) catalyst. The SOFC reactor also has good stability for co-generation of electricity and ethylene at 700 °C.

  2. Preparation of zwitterionic hydroquinone-fused [1,4]oxazinium derivatives via a photoinduced intramolecular dehydrogenative-coupling reaction.

    Science.gov (United States)

    Yi, Chenyi; Liu, Shi-Xia; Neels, Antonia; Renaud, Philippe; Decurtins, Silvio

    2009-12-03

    A simple and efficient photochemical reaction can be performed to construct functionalized [1,4]oxazinium derivatives via a direct dehydrogenative coupling between sp(3)- and sp(2)-hybridized C-atoms, starting from easily accessible stable semiquinone radicals.

  3. Mechanisms for dehydrogenation and hydrogenation of N-heterocycles using PNP-pincer-supported iron catalysts: a density functional study.

    Science.gov (United States)

    Sawatlon, Boodsarin; Surawatanawong, Panida

    2016-10-14

    The catalytic dehydrogenation and hydrogenation of N-heterocycles have potential applications in organic hydrogen storage. Recently, Fe(HPNP)(CO)(H)(HBH3) (cp1) and Fe(HPNP)(CO)(H)(Br) (cp2), the iron(ii) complexes supported by bis(phosphino)amine pincer (Fe-PNP) (PNP = N(CH2CH2P(i)Pr2)2), have been reported to be the starting complexes which can catalyze the dehydrogenation and hydrogenation of N-heterocycles. The active species were proposed to be the trans-dihydride complexes, Fe(HPNP)(CO)(H)2 (cp4) and Fe(PNP)(CO)(H) (cp3), which can be interconverted. Here, our density functional study revealed that the N-heterocyclic substrate plays a role in the formation of cp4 from cp1, while the tert-butoxide base assists with the formation of cp3 from cp2. The mechanism for cp3 catalyzed dehydrogenation of a 1,2,3,4-tetrahydroquinoline (THQ) substrate to quinoline (Q) involves two main steps: (i) dehydrogenation of THQ to 3,4-dihydroquinoline (34DHQ) and (ii) dehydrogenation of 34DHQ to Q. In each dehydrogenation step, the proton is transferred from the substrate to the N of the PNP ligand of cp3. An ion-pair complex between Fe-PNP and the deprotonated substrate is then formed before the hydride at the adjacent C is transferred to Fe. Notably, the isomerization of 34DHQ to 14DHQ or 12DHQ is not necessary, as the bifunctionality of Fe-PNP in cp3 can stabilize the ion-pair complex and facilitate direct dehydrogenation of the C3-C4 bond in 34DHQ. On the other hand, the mechanism for hydrogenation of Q involves the initial formation of 14DHQ, which can easily isomerize to 34DHQ with the assistance of a tert-butoxide base. Finally, 34DHQ is dehydrogenated to THQ. As the overall energy barriers for cp3 catalyzed dehydrogenation of THQ (+27.6 kcal mol(-1)) and cp4 catalyzed hydrogenation of Q (+23.8 kcal mol(-1)) are only slightly different, reaction conditions can be conveniently adjusted to favor either the dehydrogenation or hydrogenation process. Insights into the role of

  4. Prolidase deficiency

    Directory of Open Access Journals (Sweden)

    Masood Qazi

    2007-01-01

    Full Text Available Prolidase deficiency is a rare inborn disorder of collagen metabolism characterized by chronic recurrent skin ulceration. A seven-year-old girl and her younger sibling with clinical features and laboratory criteria fulfilling the diagnosis of prolidase deficiency are presented in view of rarity of the condition.

  5. Iodine Deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.

    2009-01-01

    Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected. Howeve

  6. Iodine Deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.

    2009-01-01

    Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected. Howeve

  7. Size-controllable APTS stabilized ruthenium(0) nanoparticles catalyst for the dehydrogenation of dimethylamine-borane at room temperature.

    Science.gov (United States)

    Zahmakıran, Mehmet; Philippot, Karine; Özkar, Saim; Chaudret, Bruno

    2012-01-14

    Dimethylamine-borane, (CH(3))(2)NHBH(3), has been considered as one of the attractive materials for the efficient storage of hydrogen, which is still one of the key issues in the "Hydrogen Economy". In a recent communication we have reported the synthesis and characterization of 3-aminopropyltriethoxysilane stabilized ruthenium(0) nanoparticles with the preliminary results for their catalytic performance in the dehydrogenation of dimethylamine-borane at room temperature. Herein, we report a complete work including (i) effect of initial [APTS]/[Ru] molar ratio on both the size and the catalytic activity of ruthenium(0) nanoparticles, (ii) collection of extensive kinetic data under non-MTL conditions depending on the substrate and catalyst concentrations to define the rate law of Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine-borane at room temperature, (iii) determination of activation parameters (E(a), ΔH(#) and ΔS(#)) for Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine-borane; (iv) demonstration of the catalytic lifetime of Ru(0)/APTS nanoparticles in the dehydrogenation of dimethylamine-borane at room temperature, (v) testing the bottlability and reusability of Ru(0)/APTS nanocatalyst in the room-temperature dehydrogenation of dimethylamine-borane, (vi) quantitative carbon disulfide (CS(2)) poisoning experiments to find a corrected TTO and TOF values on a per-active-ruthenium-atom basis, (vii) a summary of extensive literature review for the catalysts tested in the catalytic dehydrogenation of dimethylamine-borane as part of the results and discussions.

  8. Dehydrogenation of Isobutane with Carbon Dioxide over SBA-15-Supported Vanadium Oxide Catalysts

    Directory of Open Access Journals (Sweden)

    Chunling Wei

    2016-10-01

    Full Text Available A series of vanadia catalysts supported on SBA-15 (V/SBA with a vanadia (V content ranging from 1% to 11% were prepared by an incipient wetness method. Their catalytic behavior in the dehydrogenation of isobutane to isobutene with CO2 was examined. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, and temperature-programmed reduction (TPR. It was found that these catalysts were effective for the dehydrogenation reaction, and the catalytic activity is correlated with the amount of dispersed vanadium species on the SBA-15 support. The 7% V/SBA catalyst shows the highest activity, which gives 40.8% isobutane conversion and 84.8% isobutene selectivity. The SBA-15-supported vanadia exhibits higher isobutane conversion and isobutene selectivity than the MCM-41-supported one.

  9. Experimental Study of Interfacial Friction in NaBH{sub 4} Solution in Microchannel Dehydrogenation Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seok Hyun; Hwang, Sueng Sik; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2014-02-15

    Sodium borohydride (NaBH{sub 4}) is considered as a secure metal hydride for hydrogen storage and supply. In this study, the interfacial friction of two-phase flow in the dehydrogenation of aqueous NaBH{sub 4} solution in a microchannel with a hydraulic diameter of 461 μm is investigated for designing a dehydrogenation chemical reactor flow passage. Because hydrogen gas is generated by the hydrolysis of NaBH{sub 4} in the presence of a ruthenium catalyst, two different flow phases (aqueous NaBH{sub 4} solution and hydrogen gas) exist in the channel. For experimental studies, a microchannel was fabricated on a silicon wafer substrate, and 100-nm ruthenium catalyst was deposited on three sides of the channel surface. A bubbly flow pattern was observed. The experimental results indicate that the two-phase multiplier increases linearly with the void fraction, which depends on the initial concentration, reaction rate, and flow residence time.

  10. Dehydration and dehydrogenation of ethylene glycol on rutile TiO2(110).

    Science.gov (United States)

    Li, Zhenjun; Kay, Bruce D; Dohnálek, Zdenek

    2013-08-07

    The interactions of ethylene glycol with a partially reduced rutile TiO2(110) surface have been studied using temperature programmed desorption (TPD). The saturation coverage on surface Ti rows is determined to be 0.43 monolayer (ML), slightly less than one ethylene glycol per two Ti sites. Most of the adsorbed ethylene glycol (∼80%) undergoes further reactions to yield other products. Two major channels are observed, dehydration yielding ethylene and water and dehydrogenation yielding acetaldehyde and hydrogen. Hydrogen formation is rather surprising as it has not been observed previously on TiO2(110) from simple organic molecules. The coverage dependent yields of ethylene and acetaldehyde correlate well with those of water and hydrogen, respectively. Dehydration dominates at lower ethylene glycol coverages (ethylene glycol coverages (>0.2 ML). Our results suggest that the observed dehydration and dehydrogenation reactions proceed via different surface intermediates.

  11. Excellent catalytic effects of highly crumpled graphene nanosheets on hydrogenation/dehydrogenation of magnesium hydride

    Science.gov (United States)

    Liu, Guang; Wang, Yijing; Xu, Changchang; Qiu, Fangyuan; An, Cuihua; Li, Li; Jiao, Lifang; Yuan, Huatang

    2013-01-01

    Highly crumpled graphene nanosheets (GNS) with a BET surface area as high as 1159 m2 g-1 was fabricated by a thermal exfoliation method. A systematic investigation was performed on the hydrogen sorption properties of MgH2-5 wt% GNS nanocomposites acquired by ball-milling. It was found that the as-synthesized GNS exhibited a superior catalytic effect on hydrogenation/dehydrogenation of MgH2. Differential Scanning Calorimetry (DSC) and isothermal hydrogenation/dehydrogenation measurements indicated that both hydrogen sorption capacity and dehydrogenation/hydrogenation kinetics of the composites improved with increasing milling time. The composites MgH2-GNS milled for 20 h can absorb 6.6 wt% H2 within 1 min at 300 °C and 6.3 wt% within 40 min at 200 °C, even at 150 °C, it can also absorb 6.0 wt% H2 within 180 min. It was also demonstrated that MgH2-GNS-20 h could release 6.1 wt% H2 at 300 °C within 40 min. In addition, microstructure measurements based on XRD, SEM, TEM as well as Raman spectra revealed that the grain size of thus-prepared MgH2-GNS nanocomposites decreased with increasing milling time, moreover, the graphene layers were broken into smaller graphene nanosheets in a disordered and irregular manner during milling. It was confirmed that these smaller graphene nanosheets on the composite surface, providing more edge sites and hydrogen diffusion channels, prevented the nanograins from sintering and agglomerating, thus, leading to promotion of the hydrogenation/dehydrogenation kinetics of MgH2.Highly crumpled graphene nanosheets (GNS) with a BET surface area as high as 1159 m2 g-1 was fabricated by a thermal exfoliation method. A systematic investigation was performed on the hydrogen sorption properties of MgH2-5 wt% GNS nanocomposites acquired by ball-milling. It was found that the as-synthesized GNS exhibited a superior catalytic effect on hydrogenation/dehydrogenation of MgH2. Differential Scanning Calorimetry (DSC) and isothermal hydrogenation/dehydrogenation

  12. Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    L. L(a)te; E.A. Blekkan

    2002-01-01

    The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts forthe dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, theonly by-products were CO and CO2. The reaction rate of propane was found to be first order in propaneand close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with theactivation of the hydrocarbon as the rate determining step. The activation energy of the conversion ofpropane was found to be 122±6 kJ/mol.

  13. Kinetics of Oxidative Dehydrogenation of Propance over a VMgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    L.Late; E.A.Blekkan

    2002-01-01

    The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃ over a VMgO catalyst,Vanadium-magnesium-oxides are among the moste selective and active catalysts for the dehydrogenation of propance to propylene Selectivity to propylene up to about 60% was obtained at 10% conversion ,but the selectivity decreased with increasing conversion.No oxygenates were detected,the only by-products were CO and CO2 ,The reaction rate of propane was found to be first order in propane and close to zero order in oxygen ,which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate detemining step.The activation energy,of the conversion of propane was found to be 122±6 kJ/mol.

  14. A dehydrogenation mechanism of metal hydrides based on interactions between Hdelta+ and H-.

    Science.gov (United States)

    Lu, Jun; Fang, Zhigang Zak; Sohn, Hong Yong

    2006-10-16

    This paper describes a reaction mechanism that explains the dehydrogenation reactions of alkali and alkaline-earth metal hydrides. These light metal hydrides, e.g., lithium-based compounds such as LiH, LiAlH4, and LiNH2, are the focus of intense research recently as the most promising candidate materials for on-board hydrogen storage applications. Although several interesting and promising reactions and materials have been reported, most of these reported reactions and materials have been discovered by empirical means because of a general lack of understanding of any underlying principles. This paper describes an understanding of the dehydrogenation reactions on the basis of the interaction between negatively charged hydrogen (H-, electron donor) and positively charged hydrogen (Hdelta+, electron acceptor) and experimental evidence that captures and explains many observations that have been reported to date. This reaction mechanism can be used as a guidance for screening new material systems for hydrogen storage.

  15. Role of catalysts in dehydrogenation of MgH2 nanoclusters.

    Science.gov (United States)

    Larsson, Peter; Araújo, C Moysés; Larsson, J Andreas; Jena, Puru; Ahuja, Rajeev

    2008-06-17

    A fundamental understanding of the role of catalysts in dehydrogenation of MgH(2) nanoclusters is provided by carrying out first-principles calculations based on density functional theory. It is shown that the transition metal atoms Ti, V, Fe, and Ni not only lower desorption energies significantly but also continue to attract at least four hydrogen atoms even when the total hydrogen content of the cluster decreases. In particular, Fe is found to migrate from the surface sites to the interior sites during the dehydrogenation process, releasing more hydrogen as it diffuses. This diffusion mechanism may account for the fact that a small amount of catalysts is sufficient to improve the kinetics of MgH(2), which is essential for the use of this material for hydrogen storage in fuel-cell applications.

  16. Selection of mixed conducting oxides for oxidative dehydrogenation of propane with pulse experiments

    NARCIS (Netherlands)

    Crapanzano, Salvatore; Babich, Igor V.; Lefferts, Leon

    2011-01-01

    In this study, propane pulse experiments at 550 °C are used as a method to select suitable oxides for further operation of catalytic dense membrane reactor (CDMR) for oxidative dehydrogenation of propane. Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), La2NiO4+δ (LN) and PrBaCo2O5+δ (PBC) powders were used as mode

  17. Titania-catalysed oxidative dehydrogenation of ethyl lactate: effective yet selective free-radical oxidation

    NARCIS (Netherlands)

    Ramos-Fernandez, E.V.; Geels, N.J.; Shiju, N.R.; Rothenberg, G.

    2014-01-01

    We research here the catalytic oxidative dehydrogenation of ethyl lactate, as an alternative route to ethyl pyruvate. Testing various solid catalysts (Fe2O3, TiO2, V2O5/MgO-Al2O3, ZrO2, CeO2 and ZnO), we find that simple and inexpensive TiO2 efficiently catalyses this reaction under mild conditions.

  18. Crystal-phase control of molybdenum carbide nanobelts for dehydrogenation of benzyl alcohol.

    Science.gov (United States)

    Li, Zhongcheng; Chen, Chunhui; Zhan, Ensheng; Ta, Na; Li, Yong; Shen, Wenjie

    2014-05-04

    Belt-shaped molybdenum carbides in α- and β-phases were synthesized by reducing and carburizing a nano-sized α-MoO3 precursor with hydrocarbon-hydrogen mixtures at appropriate temperatures; the β-Mo2C nanobelts with a higher fraction of coordinatively unsaturated Mo sites were more active than the α-MoC1-x nanobelts in dehydrogenation of benzyl alcohol to benzaldehyde.

  19. First-principles calculation of dehydrogenating properties of MgH2-V systems

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Dianwu; PENG; Ping; LIU; Jinshui

    2006-01-01

    Based on experimental results in which VH0.81/MgH2 interface was found during the process of mechanically milling MgH2+5at%V nanocomposite, a VH/MgH2 interface is designed and constituted in this work. A first-principles plane-wave pseudopotential method based on Density Functional Theory (DFT) has been used to investigate the vanadium alloying effects on the dehydrogenating properties of magnesium hydride, i.e., MgH2. A low absolute value of the negative heat of formation of VH/MgH2 interface compared with that of MgH2 indicates that vanadium hydrides befit to improve the dehydrogenating properties of MgH2. Based on the analysis of the density of states (DOS) and the total valence electron density distribution of MgH2 before and after V alloying, it was found that the improvement of the dehydrogenating properties of MgH2 caused by V alloying originates from the increasing of the valence electrons at Fermi level (EF) and the decreasing of the HOMO-LUMO gap (△EH-L) after V alloying. The catalysis effect of V on dehydrogenating kinetics of MgH2 may attribute to a stronger bonding between V and H atoms than that between Mg and H atoms, which leads to nucleation of the α-Mg at the VH/MgH2 interface in the MgH2-V systems easier than that in pure MgH2 phase.

  20. Highly Ordered Mesoporous Metal Oxides as Catalysts for Dehydrogenation of Cyclohexanol

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eunok; Jin, Mingshi; Kim, Ji Man [Sungkyunkwan University, Suwon (Korea, Republic of)

    2013-08-15

    Cyclohexanone is important intermediate for the manufacture of caprolactam which is monomer of nylron. Cyclohexanone is generally produced by dehydrogenation reaction of cyclohexanol. In this study, highly mesoporous metal oxides such as meso-WO{sub 3}, meso-TiO{sub 2}, meso-Fe{sub 2}O{sub 3}, meso-CuO, meso-SnO{sub 2} and meso-NiO were synthesized using mesoporous silica KIT-6 as a hard template via nano-replication method for dehydrogenation of cyclohexanol. The overall conversion of cyclohexanol followed a general order: meso-WO{sub 3} >> meso-Fe{sub 2}O{sub 3} > meso-SnO{sub 2} > meso-TiO{sub 2} > meso-NiO > meso-CuO. In particular, meso-WO{sub 3} significantly showed higher activity than the other mesoporous metal oxides. Therefore, the meso-WO{sub 3} has wide range of application possibilities for dehydrogenation of cyclohexanol.

  1. Theoretical Study of Palladium Membrane Reactor Performance During Propane Dehydrogenation Using CFD Method

    Directory of Open Access Journals (Sweden)

    Kamran Ghasemzadeh

    2017-04-01

    Full Text Available This study presents a 2D-axisymmetric computational fluid dynamic (CFD model to investigate the performance Pd membrane reactor (MR during propane dehydrogenation process for hydrogen production. The proposed CFD model provided the local information of temperature and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of CFD model results was carried out by other modeling data and a good agreement between CFD model results and theoretical data was achieved. Indeed, in the present model, a tubular reactor with length of 150 mm was considered, in which the Pt-Sn-K/Al2O3 as catalyst were filled in reaction zone. Hence, the effects of the important operating parameter (reaction temperature on the performances of membrane reactor (MR were studied in terms of propane conversion and hydrogen yield. The CFD results showed that the suggested MR system during propane dehydrogenation reaction presents higher performance with respect to once obtained in the conventional reactor (CR. In particular, by applying Pd membrane, was found that propane conversion can be increased from 41% to 49%. Moreover, the highest value of propane conversion (X = 91% was reached in case of Pd-Ag MR. It was also established that the feed flow rate of the MR is to be the one of the most important factors defining efficiency of the propane dehydrogenation process.

  2. Identifying active functionalities on few-layered graphene catalysts for oxidative dehydrogenation of isobutane.

    Science.gov (United States)

    Dathar, Gopi Krishna Phani; Tsai, Yu-Tung; Gierszal, Kamil; Xu, Ye; Liang, Chengdu; Rondinone, Adam J; Overbury, Steven H; Schwartz, Viviane

    2014-02-01

    The general consensus in the studies of nanostructured carbon catalysts for oxidative dehydrogenation (ODH) of alkanes to olefins is that the oxygen functionalities generated during synthesis and reaction are responsible for the catalytic activity of these nanostructured carbons. Identification of the highly active oxygen functionalities would enable engineering of nanocarbons for ODH of alkanes. Few-layered graphenes were used as model catalysts in experiments to synthesize reduced graphene oxide samples with varying oxygen concentrations, to characterize oxygen functionalities, and to measure the activation energies for ODH of isobutane. Periodic density functional theory calculations were performed on graphene nanoribbon models with a variety of oxygen functionalities at the edges to calculate their thermal stability and to model reaction mechanisms for ODH of isobutane. Comparing measured and calculated thermal stability and activation energies leads to the conclusion that dicarbonyls at the zigzag edges and quinones at armchair edges are appropriately balanced for high activity, relative to other model functionalities considered herein. In the ODH of isobutane, both dehydrogenation and regeneration of catalytic sites are relevant at the dicarbonyls, whereas regeneration is facile compared with dehydrogenation at quinones. The catalytic mechanism involves weakly adsorbed isobutane reducing functional oxygen and leaving as isobutene, and O2 in the feed, weakly adsorbed on the hydrogenated functionality, reacting with that hydrogen and regenerating the catalytic sites.

  3. An experimental survey of additives for improving dehydrogenation properties of magnesium hydride

    Science.gov (United States)

    Zhou, Chengshang; Fang, Zhigang Zak; Sun, Pei

    2015-03-01

    The use of a wide range of additives has been known as an important method for improving hydrogen storage properties of MgH2. There is a lack of a standard methodology, however, that can be used to select or compare the effectiveness of different additives. A systematic experimental survey was carried out in this study to compare a wide range of additives including transitions metals, transition metal oxides, hydrides, intermetallic compounds, and carbon materials, with respect to their effects on dehydrogenation properties of MgH2. MgH2 with various additives were prepared by using a high-energy-high-pressure planetary ball milling method and characterized by using thermogravimetric analysis (TGA) techniques. The results showed that additives such as Ti and V-based metals, hydride, and certain intermetallic compounds have strong catalytic effects. Additives such as Al, In, Sn, Si showed minor effects on the kinetics of the dehydrogenation of MgH2, while exhibiting moderate thermodynamic destabilizing effects. In combination, MgH2 with both kinetic and thermodynamic additives, such as the MgH2-In-TiMn2 system, exhibited a drastically decreased dehydrogenation temperature.

  4. Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

    Directory of Open Access Journals (Sweden)

    Zeeshan Nawaz

    2009-12-01

    Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

  5. Experimental Study and Kinetic Modeling of Decoking of Pacol Process Dehydrogenation Catalyst

    Directory of Open Access Journals (Sweden)

    M. Toghyani

    2015-07-01

    Full Text Available The Pt/γ-Al2O3 catalyst life time was limited by the formation of coke on the external and internal surfaces of catalyst in dehydrogenation reactors. The kinetics of decoking of dehydrogenation catalyst was studied in a pilot scale fixed bed reactor experimentally. The effects of temperature, oxygen concentration and other operating conditions on decoking process were investigated. A kinetic model was deve-loped to describe the decoking of mentioned catalyst. An objective function was defined as the sum of squares of the deviations among the calculated and plant data. Accordingly the appropriate values were found in order to minimize this function. It was concluded that there was a good agreement between simulation results and experimental data.  © 2015 BCREC UNDIP. All rights reservedReceived: 18th September 2014; Revised: 28th February 2015; Accepted: 9th March 2015How to Cite: Toghyani, M., Rahimi, A., Mamanpoush, M., Kazemian, R., Harandizadeh, A.H. (2015. Experimental Study and Kinetic Modeling of Decoking of Pacol Process Dehydrogenation Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 155-161. (doi:10.9767/bcrec.10.2.7357.155-161 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7357.155-161  

  6. Iodine Deficiency

    Science.gov (United States)

    ... 0 Iodine Daily Serving now recommended in Multivitamin/Mineral Supplements for Pregnant and Lactating Women By ATA | 2015 News Releases , Iodine Deficiency , News Releases , Thyroid Disease and Pregnancy | No Comments Falls Church, February 10, 2015 —The ...

  7. Iron deficiency.

    Science.gov (United States)

    Scrimshaw, N S

    1991-10-01

    The world's leading nutritional problem is iron deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. Iron deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune system which reduces the body's ability to fight infection. Iron deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's iron. This iron is always being recycled as more red blood cells are made. The rest of the needed iron does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This iron comes from our diet, especially meat. Even though some plants, such as spinach, are high in iron, the body can only absorb 1.4-7% of the iron in plants whereas it can absorb 20% of the iron in red meat. In many developing countries, the common vegetarian diets contribute to high rates of iron deficiency. Parasitic diseases and abnormal uterine bleeding also promote iron deficiency. Iron therapy in anemic children can often, but not always, improve behavior and cognitive performance. Iron deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess iron can be damaging. Too much supplemental iron in a malnourished child promotes fatal infections since the excess iron is available for the pathogens use. Many countries do not have an effective system for diagnosing, treating, and preventing iron deficiency. Therefore a concerted international effort is needed to eliminate iron deficiency in the world.

  8. Influence of Particle Size on Reaction Selectivity in Cyclohexene Hydrogenation and Dehydrogenation over Silica-Supported Monodisperse Pt Particles

    Energy Technology Data Exchange (ETDEWEB)

    Rioux, R. M.; Hsu, B. B.; Grass, M. E.; Song, H.; Somorjai, Gabor A.

    2008-07-11

    The role of particle size during the hydrogenation/dehydrogenation of cyclohexene (10 Torr C{sub 6}H{sub 10}, 200-600 Torr H{sub 2}, and 273-650 K) was studied over a series of monodisperse Pt/SBA-15 catalysts. The conversion of cyclohexene in the presence of excess H{sub 2} (H{sub 2}:C{sub 6}H{sub 10} ratio = 20-60) is characterized by three regimes: hydrogenation of cyclohexene to cyclohexane at low temperature (< 423 K), an intermediate temperature range in which both hydrogenation and dehydrogenation occur; and a high temperature regime in which the dehydrogenation of cyclohexene dominates (> 573 K). The rate of both reactions demonstrated maxima with temperature, regardless of Pt particle size. For the hydrogenation of cyclohexene, a non-Arrhenius temperature dependence (apparent negative activation energy) was observed. Hydrogenation is structure insensitive at low temperatures, and apparently structure sensitive in the non-Arrhenius regime; the origin of the particle-size dependent reactivity with temperature is attributed to a change in the coverage of reactive hydrogen. Small particles were more active for dehydrogenation and had lower apparent activation energies than large particles. The selectivity can be controlled by changing the particle size, which is attributed to the structure sensitivity of both reactions in the temperature regime where hydrogenation and dehydrogenation are catalyzed simultaneously.

  9. Cobalamin deficiency.

    Science.gov (United States)

    Herrmann, Wolfgang; Obeid, Rima

    2012-01-01

    Cobalamin (Cbl, vitamin B12) consists of a corrinoid structure with cobalt in the centre of the molecule. Neither humans nor animals are able to synthesize this vitamin. Foods of animal source are the only natural source of cobalamin in human diet. There are only two enzymatic reactions in mammalian cells that require cobalamin as cofactor. Methylcobolamin is a cofactor for methionine synthase. The enzyme methylmalonyl-CoA-mutase requires adenosylcobalamin as a cofactor. Therefore, serum concentrations of homocysteine (tHcy) and methylmalonic acid (MMA) will increase in cobalamin deficiency. The cobalamin absorption from diet is a complex process that involves different proteins: haptocorrin, intrinsic factor and transcobalamin (TC). Cobalamin that is bound to TC is called holotranscobalamin (holoTC) which is the metabolically active vitamin B12 fraction. HoloTC consists 6 and 20% of total cobalamin whereas 80% of total serum cobalamin is bound to another binding protein, haptocorrin. Cobalamin deficiency is common worldwide. Cobalamin malabsorption is common in elderly subjects which might explain low vitamin status. Subjects who ingest low amount of cobalamin like vegetarians develop vitamin deficiency. No single parameter can be used to diagnose cobalamin deficiency. Total serum cobalamin is neither sensitive nor it is specific for cobalamin deficiency. This might explain why many deficient subjects would be overlooked by utilizing total cobalamin as status marker. Concentration of holotranscobalamin (holoTC) in serum is an earlier marker that becomes decreased before total serum cobalamin. Concentrations of MMA and tHcy increase in blood of cobalamin deficient subjects. Despite limitations of these markers in patients with renal dysfunction, concentrations of MMA and tHcy are useful functional markers of cobalamin status. The combined use of holoTC and MMA assays may better indicate cobalamin status than either of them. Because Cbl deficiency is a risk factor

  10. Dehydrogenation of propane in the presence of carbon dioxide over chromium and gallium oxides catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Menshova, M.V.; Kunusova, R.M. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2011-07-01

    Effective chromium and gallium oxides supported catalysts were prepared and tested in longduration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of active metals were found. It was shown that the activity, selectivity and stability of chromium oxides catalysts were higher than these parameters for gallium ones. Mechanism of propane oxidative dehydrogenation was studied over both catalysts using unstationary and spectroscopic methods. The employment of these methods allowed to establish the differences in process mechanism. It was shown that surface hydroxides took participation in propene formation over Cr-catalysts and hydrides - over Ga-ones. Propane and carbon dioxide participated in the reaction from the adsorbed state over both catalysts but they were differed by the adsorption capacity of the reaction components: CO2 was tied more firmly than C{sub 3}H{sub 6} over both catalysts, CO{sub 2} and C{sub 3}H{sub 6} were tied more strongly with Cr-catalysts than with Ga-ones. It was shown that CO{sub 2} took active participation in reverse watergas shift reaction and in oxidation of catalyst surface over chromium oxides catalysts. The main role of CO{sub 2} in propane dehydrogenation over gallium catalysts consisted in a decrease of coke formation. Step-schemes of propene and cracking products formation were proposed on the basis of literature and obtained data: via the redox mechanism over Cr-catalysts and through a heterolytic dissociation reaction pathway over Ga-ones. (orig.)

  11. Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

    1998-12-31

    Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

  12. VLCAD deficiency

    DEFF Research Database (Denmark)

    Boneh, A; Andresen, B S; Gregersen, N

    2006-01-01

    We diagnosed six newborn babies with very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) through newborn screening in three years in Victoria (prevalence rate: 1:31,500). We identified seven known and two new mutations in our patients (2/6 homozygotes; 4/6 compound heterozygotes). Blood...

  13. Effect of catalyst structure on oxidative dehydrogenation of ethane and propane on alumina-supported vanadia

    Energy Technology Data Exchange (ETDEWEB)

    Argyle, Morris D.; Chen, Kaidong; Bell, Alexis T.; Iglesia, Enrique

    2001-09-11

    The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm2) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominantly as isolated monovanadate species below {approx}2.3 V/nm2. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm2) along with increasing amounts of V2O5 crystallites at surface densities above 7.0 V/nm2. The rate constant for oxidative dehydrogenation (k1) and its ratio with alkane and alkene combustion (k2/k1 and k3/k1, respectively) were compared for both alkane reactants as a function of vanadia surface density. Propene formation rates (per V-atom) are {approx}8 times higher than ethene formation rates at a given reaction temperature, but the apparent ODH activation energies (E1) are similar for the two reactants and relatively insensitive to vanadia surface density. Ethene and propene formation rates (per V-atom) are strongly influenced by vanadia surface density and reach a maximum value at intermediate surface densities ({approx}8 V/nm2). The ratio of k2/k1 depends weakly on reaction temperature, indicating that activation energies for alkane combustion and ODH reactions are similar. The ratio of k2/k1 is independent of surface density for ethane, but increase slightly with vanadia surface density for propane, suggesting that isolated structures prevalent at low surface densities are slightly more selective for alkane dehydrogenation reactions. The ratio of k3/k1 decreases markedly with increasing reaction temperature for both ethane and propane ODH. Thus, the apparent activation energy for alkene combustion (E3) is much lower than that for alkane dehydrogenation (E1) and the difference between these two activation energies decreases with increasing surface density. The lower alkene selectivities observed at high vanadia surface densities are attributed to an

  14. A STUDY ON MEMBRANE PROCESS WITH γ-ALUMINA MEMBRANE REACTOR FOR ETHYLBENZENE DEHYDROGENATION TO STYRENE

    Institute of Scientific and Technical Information of China (English)

    Chen Qingling; Xu Zhongqiang

    2001-01-01

    The membrane reaction of ethylbenzene(EB) dehydrogenation to styrene(ST) has been studied by using K2O/Fe2O3 industrial catalyst and γ-alumina ceramic membrane developed by our institute. In comparison with the packed bed reactor (that is, plug flow reactor, abbr. PFR) in industrial practice, the yield of styrene was increased by 5%~10% in the membrane reactor. Furthermore, mathematical modeling of membrane reaction has been studied to display the principle of optimal match between the catalytic activity and the membrane permeability.

  15. Ammonia-Borane and Amine-Borane Dehydrogenation Mediated by Complex Metal Hydrides.

    Science.gov (United States)

    Rossin, Andrea; Peruzzini, Maurizio

    2016-08-10

    This review is a comprehensive survey of the last 10 years of research on ammonia-borane and amine-borane dehydrogenation mediated by complex metal hydrides (CMHs), within the broader context of chemical hydrogen storage. The review also collects those cases where CMHs are the catalyst spent form or its resting state. Highlights on the reaction mechanism (strictly dependent on the CMH of choice) and the catalysts efficiency (in terms of equivalents of H2 produced and relative reaction rates) are provided throughout the discussion.

  16. Oxidative Dehydrogenation of Ethane to Ethylene over LiCI/MnOx/PC Catalysts

    Institute of Scientific and Technical Information of China (English)

    葛庆杰; 李文钊; 于春英; 徐恒泳

    2001-01-01

    The caalytic stability of LiCl/MnOx/PC catalyst have been investigated, the deactivation mechanism was discussed. Tne experimental results show that ethane conversion decreases and etihylene selectivotu keeps about 90% as reaction time increases. The main deactivation reasons LiCI/MnOx/PCcatalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transiton of active species Mn2O3 TO MnOspecies and the loss of active component Cl in catalyst. Instead of ethane with FCC tailed-gas, the stability of LiCl/MnOx/PC catalyst has been largely improved.

  17. Dynamic Structure of Mo-O Species in Ag-Mo-P-O Catalyst for Oxidative Dehydrogenation of Propane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The dynamic structure of Mo-O species in Ag-Mo-P-O catalyst was studied by in situ confocal microprobe laser Raman spectroscopy (LRS) and catalytic test. The results indicate Mo-O species of MoO3 transformed to Mo-O species of AgMoO2PO4 in C3H8/O2/N2 (3/1/4) flow at 773 K. This behavior is closely relative to oxidative dehydrogenation of propane and intrinsic properties of Mo-O species. The Mo-O species of AgMoO2PO4 may be active species for oxidative dehydrogenation of propane.

  18. DNA-based prenatal diagnosis for severe and variant forms of multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Andresen, Brage S; Christensen, Ernst;

    2005-01-01

    , prenatal diagnosis of MADD has relied mostly on second-trimester biochemical analyses of amniotic fluid or cultured amniocytes. We report here on an alternative DNA-based approach for prenatal diagnosis in pregnancies at risk of MADD. METHODS: We used our knowledge of the mutational status in three...

  19. Clear relationship between ETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Andresen, Brage S; Christensen, Ernst;

    2003-01-01

    activity, we have investigated the molecular genetic basis for disease development in nine patients representing the phenotypic spectrum of MADD. We report the genomic structures of the ETFA, ETFB, and ETFDH genes and the identification and characterization of seven novel and three previously reported...

  20. ETFDH mutations as a major cause of riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Olpin, Simon E; Andresen, Brage S;

    2007-01-01

    of riboflavin. It is unknown whether these patients have defects in the flavoproteins themselves or defects in the formation of the cofactor, FAD, from riboflavin. We report 15 patients from 11 pedigrees. All the index cases presented with encephalopathy or muscle weakness or a combination of these symptoms...

  1. Effect of Impregnation Sequence on Propane Dehydrogenation Performance of PtSnNa/ZSM-5 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Liu Hui; Zhou Yuming; Zhang Yiwei; Sheng Xiaoli; Zhang Zewu; Zhou Shijiang

    2013-01-01

    The effects of the sequence for impregnation of metal precursors on the performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation to propene were studied in this paper. Some methods such as XRD, TPDA,BET, H2-TPR, XPS, ICP, TEM and hydrogen chemisorption were used to characterize the catalysts. The structure of ZSM-5 zeolite was not destroyed by the introduction of metal components. Meanwhile the different impregnation sequence of metal precursors could affect the behavior of Sn4+ species entering the ZSM-5 channel, and the interaction between platinum and tin species, as well as the degree for reduction of Pt and Sn components. As a result, the prepared catalysts exhibited different reac-tion activity and selectivity. Compared with the co-impregnation treated catalyst, the catalysts prepared by the sequential impregnation method showed better catalytic activity in propane dehydrogenation, especially the one prepared through im-pregnation with tin precursor at ifrst. Finally, a model for the effect of impregnation sequence on the distribution of Pt and Sn species in PtSnNa/ZSM-5 catalyst was proposed.

  2. Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Baroi, Chinmoy; Gaffney, Anne M.; Fushimi, Rebecca

    2017-05-01

    Olefins or unsaturated hydrocarbons play a vital role as feedstock for many industrially significant processes. Ethylene is the simplest olefin and a key raw material for consumer products. Oxidative Dehydrogenation (ODH) is one of the most promising new routes for ethylene production that can offer a significant advantage in energy efficiency over the conventional steam pyrolysis process. This study is focused on the ODH chemistry using the mixed metal oxide MoVTeNbOx catalysts, generally referred to as M1 for the key phase known to be active for dehydrogenation. Using performance results from the patent literature a series of process simulations were conducted to evaluate the effect of feed composition on operating costs, profitability and process safety. The key results of this study indicate that the ODH reaction can be made safer and more profitable without use of an inert diluent and furthermore by replacing O2 with CO2 as an oxidant. Modifications of the M1 catalyst composition in order to adopt these changes are discussed.

  3. Final Technical Report: Tandem and Bimetallic Catalysts for Oxidative Dehydrogenation of Light Hydrocarbon with Renewable Feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Omar, Mahdi [Purdue Univ., West Lafayette, IN (United States)

    2017-01-06

    An estimated 490 million metric tons of lignocellulosic biomass is available annually from U.S. agriculture and forestry. With continuing concerns over greenhouse gas emission, the development of efficient catalytic processes for conversion of biomass derived compounds is an important area of research. Since carbohydrates and polyols are rich in oxygen, approximately one oxygen atom per carbon, removal of hydroxyl groups via deoxygenation is needed. The necessary hydrogen required for hydrodeoxygenation (HDO) would either come from reforming biomass itself or from steam reforming of natural gas. Both processes contribute to global CO2 emission. The hope is that eventually renewable sources such as wind and solar for hydrogen production will become more viable and economic in the future. In the meantime, unconventional natural gas production in North America has boomed. As a result, light hydrocarbons present an opportunity when coupled with biomass derived oxygenates to generate valuable products from both streams without co-production of carbon dioxide. This concept is the focus of our current funding period. The objective of the project requires coupling two different types of catalysis, HDO and dehydrogenation. Our hypothesis was formulated around our success in establishing oxorhenium catalysts for polyol HDO reactions and known literature precedence for the use of iridium hydrides in alkane dehydrogenation. To examine our hypothesis we set out to investigate the reaction chemistry of binuclear complexes of oxorhenium and iridium hydride.

  4. Low-valent iron(i) amido olefin complexes as promotors for dehydrogenation reactions.

    Science.gov (United States)

    Lichtenberg, Crispin; Viciu, Liliana; Adelhardt, Mario; Sutter, Jörg; Meyer, Karsten; de Bruin, Bas; Grützmacher, Hansjörg

    2015-05-01

    Fe(I) compounds including hydrogenases show remarkable properties and reactivities. Several iron(I) complexes have been established in stoichiometric reactions as model compounds for N2 or CO2 activation. The development of well-defined iron(I) complexes for catalytic transformations remains a challenge. The few examples include cross-coupling reactions, hydrogenations of terminal olefins, and azide functionalizations. Here the syntheses and properties of bimetallic complexes [MFe(I) (trop2 dae)(solv)] (M=Na, solv=3 thf; M=Li, solv=2 Et2 O; trop=5H-dibenzo[a,d]cyclo-hepten-5-yl, dae=(N-CH2 -CH2 -N) with a d(7) Fe low-spin valence-electron configuration are reported. Both compounds promote the dehydrogenation of N,N-dimethylaminoborane, and the former is a precatalyst for the dehydrogenative alcoholysis of silanes. No indications for heterogeneous catalyses were found. High activities and complete conversions were observed particularly with [NaFe(I) (trop2 dae)(thf)3 ].

  5. Oxidative dehydrogenation of ethane on rare-earth oxide-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Buyevskaya, O.; Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    1998-12-31

    Results on the oxidative dehydrogenation of ethane on rare-earth oxide (REO) based catalysts (Na-P-Sm-O, Sm-Sr(Ca)-O, La-Sr-O and Nd-Sr-O) are described. Oxygen adsorption was found to be a key factor which determines the activity of this type of catalysts. Continuous flow experiments in the presence of catalysts which reveal strong oxygen adsorption showed that the reaction mixture is ignited resulting in an enhanced heat generation at the reactor inlet. The heat produced by the oxidative reactions was sufficient under the conditions chosen for the endothermic thermal pyrolysis which takes place preferentially in the gas phase. Ignition of the reaction mixture is an important catalyst function. Contrary to non-catalytic oxidative dehydrogenation, reaction temperatures above 700 C could be achieved without significant external heat input. Ethylene yields of up to 34-45% (S=66-73%) were obtained on REO-based catalysts under non-isothermal conditions (T{sub max}=810-865 C) at contact times in the order of 30 to 40 ms. (orig.)

  6. Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Luma M. Ahmed

    2014-01-01

    Full Text Available Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100. The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, atomic force microscopy (AFM, and UV-visible diffuse spectrophotometry (UV-Vis. XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

  7. Effect of transition-metal additives on dehydrogenation kinetics of MgH2

    Science.gov (United States)

    Roy, Anindya; Janotti, Anderson; van de Walle, Chris G.

    2013-03-01

    Using first-principles calculations based on hybrid density functional theory we study the (de)hydrogenation process in MgH2, an important solid-state hydrogen storage material. This reaction proceeds through diffusion processes, mediated by native point defects such as vacancies and interstitials. Reducing the formation energy of relevant defects increases their concentrations, resulting in higher diffusion rates and an enhancement in kinetics. We investigate the formation energies of native point defects in MgH2 and determine the position of the Fermi level in the band gap using the charge neutrality condition. The presence of transition-metal (TM) impurities (Ti, Fe, Co and Ni) causes the Fermi level to shift according to the position of the TM acceptor/donor levels in the band gap. This shift can bring down the formation energy of native defects. Our calculations predict that all of the TM additives, in either interstitial or substitutional configurations, may cause such a shift in the Fermi level and thus increase the concentration of the hydrogen vacancies that govern hydrogen diffusion. Our proposed mechanism explains the experimentally observed enhancement in the rate of dehydrogenation of MgH2 upon addition of TM impurities. U.S. Department of Energy (Grant No. DE-FG02-07ER46434), National Energy Research Scientific Computing Center

  8. Formic Acid Dehydrogenation on Au-Based Catalysts at Near-Ambient Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda, Manuel; Iglesia, Enrique

    2008-11-24

    Formic acid (HCOOH) is a convenient hydrogen carrier in fuel cells designed for portable use. Recent studies have shown that HCOOH decomposition is catalyzed with Ru-based complexes in the aqueous phase at near-ambient temperatures. HCOOH decomposition reactions are used frequently to probe the effects of alloying and cluster size and of geometric and electronic factors in catalysis. These studies have concluded that Pt is the most active metal for HCOOH decomposition, at least as large crystallites and extended surfaces. The identity and oxidation state of surface metal atoms influence the relative rates of dehydrogenation (HCOOH {yields} H{sub 2} + CO{sub 2}) and dehydration (HCOOH {yields} H{sub 2}O + CO) routes, a selectivity requirement for the synthesis of CO-free H{sub 2} streams for low-temperature fuel cells. Group Ib and Group VIII noble metals catalyze dehydrogenation selectively, while base metals and metal oxides catalyze both routes, either directly or indirectly via subsequent water-gas shift (WGS) reactions.

  9. Theoretical Study on the Dehydrogenation Reaction of H2S by VS+ (3∑-)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The dehydrogenation reaction of H2S by the 3∑- ground state of VS+: VS+ + H2S → VS2+ + H2 has been studied by using Density Functional Theory (DFT) at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways (A and B) yielding two isomer dehydrogenation products VS2+-1 (3B2) and VS2+-2 (3A1), respectively. For both pathways,the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V+, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.

  10. ENHANCEMENT OF EQUILIBRIUMSHIFT IN DEHYDROGENATION REACTIONS USING A NOVEL MEMBRANE REACTOR

    Energy Technology Data Exchange (ETDEWEB)

    Shamsuddin Ilias, Ph.d., P.E.; Franklin G. King, D.Sc.

    2001-02-13

    With the advances in new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Inorganic and composite membranes are being considered as potential candidates for use in membrane-reactor configuration for effectively increasing reaction rate, selectivity and yield of equilibrium limited reactions. To investigate the usefulness of a palladium-ceramic composite membrane in a membrane reactor-separator configuration, we investigated the dehydrogenation of cyclohexane by equilibrium shift. A two-dimensional pseudo-homogeneous reactor model was developed to study the dehydrogenation of cyclohexane by equilibrium shift in a tubular membrane reactor. Radial diffusion was considered to account for the concentration gradient in the radial direction due to permeation through the membrane. For a dehydrogenation reaction, the feed stream to the reaction side contained cyclohexane and argon, while the separation side used argon as the sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. The present study showed that 100% conversion could be achieved by equilibrium shift using Pd-ceramic membrane reactor. For a feed containing cyclohexane and argon of 1.64 x 10{sup -6} and 1.0 x 10{sup -3} mol/s, over 98% conversion could be readily achieved. The dehydrogenation of cyclohexane was also experimentally investigated in a palladium-ceramic membrane reactor. The Pd-ceramic membrane was fabricated by electroless deposition of palladium on ceramic substrate. The performance of Pd-ceramic membrane was compared with a commercially available hydrogen-selective ceramic membrane. From limited experimental data it was observed that by appropriate choice of feed flow rate and sweep gas rate, the conversion of cyclohexane to benzene and hydrogen can increased to 56% at atmospheric pressure and 200 C in a Pd-ceramic membrane reactor. In the commercial ceramic membrane

  11. ENHANCEMENT OF EQUILIBRIUMSHIFT IN DEHYDROGENATION REACTIONS USING A NOVEL MEMBRANE REACTOR

    Energy Technology Data Exchange (ETDEWEB)

    Shamsuddin Ilias, Ph.d., P.E.; Franklin G. King, D.Sc.

    2001-02-13

    With the advances in new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Inorganic and composite membranes are being considered as potential candidates for use in membrane-reactor configuration for effectively increasing reaction rate, selectivity and yield of equilibrium limited reactions. To investigate the usefulness of a palladium-ceramic composite membrane in a membrane reactor-separator configuration, we investigated the dehydrogenation of cyclohexane by equilibrium shift. A two-dimensional pseudo-homogeneous reactor model was developed to study the dehydrogenation of cyclohexane by equilibrium shift in a tubular membrane reactor. Radial diffusion was considered to account for the concentration gradient in the radial direction due to permeation through the membrane. For a dehydrogenation reaction, the feed stream to the reaction side contained cyclohexane and argon, while the separation side used argon as the sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. The present study showed that 100% conversion could be achieved by equilibrium shift using Pd-ceramic membrane reactor. For a feed containing cyclohexane and argon of 1.64 x 10{sup -6} and 1.0 x 10{sup -3} mol/s, over 98% conversion could be readily achieved. The dehydrogenation of cyclohexane was also experimentally investigated in a palladium-ceramic membrane reactor. The Pd-ceramic membrane was fabricated by electroless deposition of palladium on ceramic substrate. The performance of Pd-ceramic membrane was compared with a commercially available hydrogen-selective ceramic membrane. From limited experimental data it was observed that by appropriate choice of feed flow rate and sweep gas rate, the conversion of cyclohexane to benzene and hydrogen can increased to 56% at atmospheric pressure and 200 C in a Pd-ceramic membrane reactor. In the commercial ceramic membrane

  12. Oxidative Dehydrogenation of n-Butenes to 1,3-Butadiene over Bismuth Molybdate and Ferrite Catalysts: A Review

    KAUST Repository

    Hong, Eunpyo

    2015-11-02

    1,3-Butadiene, an important raw material for a variety of chemical products, can be produced via the oxidative dehydrogenation (ODH) of n-butenes over multicomponent oxide catalysts based on bismuth molybdates and ferrites. In this review, the basic concept, reaction mechanism, and catalysts typically used in an ODH reaction are discussed. © 2015, Springer Science+Business Media New York.

  13. The kinetic and mechanistic aspects of the oxidative dehydrogenation of ethane over Li/Na/MgO catalysts

    NARCIS (Netherlands)

    Swaan, H.M.; Swaan, H.M.; Toebes, A.; Toebes, A.; van Ommen, J.G.; Seshan, Kulathuiyer; Ross, J.R.H.; Ross, J.R.H.

    1992-01-01

    Kinetic and mechanistic aspects of the oxidative dehydrogenation of ethane catalysed by Li/MgO and Li/Na/MgO have been investigated. Initial rate measurements at 600°C; revealed that the Li/MgO catalyst produced C2H4, CO2, CO and H2 by parallel reactions whereas the sodium-promoted catalyst produced

  14. The oxidative dehydrogenation of methanol to formaldehyde over silver catalysts in relation to the oxygen-silver interaction

    NARCIS (Netherlands)

    Lefferts, Leonardus; van Ommen, J.G.; Ross, J.R.H.

    1986-01-01

    The properties of silver in the oxidative dehydrogenation of methanol were studied in a flow reactor under near industrial conditions. The influences of temperature, concentration of both reactants, gas velocity, space velocity, the form of the silver catalyst and surface composition of the catalyst

  15. Base-Free Production of H-2 by Dehydrogenation of Formic Acid Using An Iridium-bisMETAMORPhos Complex

    NARCIS (Netherlands)

    Oldenhof, S.; de Bruin, B.; Lutz, M.; Siegler, M.A.; Patureau, F.W.; van der Vlugt, J.I.; Reek, J.N.H.

    2013-01-01

    An iridium complex based on a cooperative ligand that functions as an internal base is reported. This complex can rapidly and cleanly dehydrogenate formic acid in absence of external base, a reaction that is required if formic acid is to be exploited as an energy carrier (see scheme).

  16. Influence of Ionic Liquids on an Iron(III) Catalyzed Three-Component Coupling/Hydroarylation/Dehydrogenation Tandem Reaction.

    Science.gov (United States)

    Muntzeck, Maren; Wilhelm, René

    2016-06-01

    A three-component oxidative dehydrogenation tandem reaction via the coupling and hydroarylation of benzaldehyde, aniline and phenylacetylene to a quinoline derivate was catalyzed by an iron-containing ionic liquid. The reaction was air mediated and could be performed under neat conditions. The iron(III) of the ionic liquid was the oxidizing species.

  17. Making coke a more efficient catalyst in the oxidative dehydrogenation of ethylbenzene using wide-pore transitional aluminas

    NARCIS (Netherlands)

    Zarubina, V.; Nederlof, C.; Linden, B. van der; Kapteijn, F.; Heeres, H.J.; Makkee, M.; Melián-Cabrera, I.

    2014-01-01

    The thermal activation of a silica-stabilized gamma-alumina impacts positively on the oxidative dehydrogenation of ethylbenzene (EB) to styrene (ST). A systematic thermal study reveals that the transition from gamma-alumina into transitional phases at 1050 degrees C leads to an optimal enhancement o

  18. A Free-Radical-Promoted Site-Specific Cross-Dehydrogenative-Coupling of N-Heterocycles with Fluorinated Alcohols.

    Science.gov (United States)

    Xu, Zhengbao; Hang, Zhaojia; Chai, Li; Liu, Zhong-Quan

    2016-09-16

    A C-C formation of an electron-rich N-heterocycle with fluorinated alcohol is developed. Through this radical-triggered cross-dehydrogenative coupling strategy, a wide range of useful building blocks such as C3 hydroxyfluoroalkylated indoles and pyrroles can be site-specifically synthesized. Mechanistic studies indicate a single-electron-transfer initiated radical cycle would be involved.

  19. Facile preparation of β-/γ-MgH₂ nanocomposites under mild conditions and pathways to rapid dehydrogenation.

    Science.gov (United States)

    Xiao, Xuezhang; Liu, Zhe; Saremi-Yarahmadi, Sina; Gregory, Duncan H

    2016-04-21

    A magnesium hydride composite with enhanced hydrogen desorption kinetics can be synthesized via a simple wet chemical route by ball milling MgH2 with LiCl as an additive at room temperature followed by tetrahydrofuran (THF) treatment under an Ar atmosphere. The as-synthesized composite comprises ca. 18 mass% orthorhombic γ-MgH2 and 80 mass% tetragonal β-MgH2 as submicron-sized particles. The β-/γ-MgH2 nanocomposite exhibits a dehydrogenation capacity of 6.6 wt% and starts to release hydrogen at ∼260 °C; ca. 140 °C lower than that of commercial MgH2. The apparent activation energy for dehydrogenation is 115 ± 3 kJ mol(-1), which is ca. 46% lower than that of commercial MgH2. Analysis suggests that the meta-stable γ-MgH2 component either directly dehydrogenates exothermically or first transforms into stable β-MgH2 very close to the dehydrogenation onset. The improved hydrogen release performance can be attributed both to the existence of the MgH2 nanostructure and to the presence of γ-MgH2.

  20. Kinetics and Mechanism of the Reaction of Coherently Synchronized Oxidation and Dehydrogenation of Cyclohexane by Hydrogen Peroxide

    Directory of Open Access Journals (Sweden)

    Aghamammadova S.

    2016-01-01

    Based on this experimental researches, the complex reaction, consisting of parallel-sequential oxidation and dehydrogenation reactions, which are coherently synchronized, proceeds during the process of cyclohexane oxidation with biomimetic catalyst. Depending on the reaction parameters it is possible to deliberately adjust the direction of oxidation reaction and reaction rate.

  1. Compositional effects on the hydrogen storage properties of Mg(NH2)2-2LiH-xKH and the activity of KH during dehydrogenation reactions.

    Science.gov (United States)

    Li, Chao; Liu, Yongfeng; Pang, Yuepeng; Gu, Yingjie; Gao, Mingxia; Pan, Hongge

    2014-02-14

    Potassium hydride (KH) was directly added to a Mg(NH2)2-2LiH system to improve the hydrogen storage properties; the corresponding mechanisms were elucidated. The Mg(NH2)2-2LiH-0.08KH composite displays optimized hydrogen-storage properties, reversibly storing approximately 5.2 wt% hydrogen through a two-stage reaction and a dehydrogenation onset at 70 °C. The 0.08KH-added sample fully dehydrogenated at 130 °C begins to absorb hydrogen at 50 °C, and takes up approximately 5.1 wt% of hydrogen at 140 °C. Adding KH significantly enhances the de-/hydrogenation kinetic properties; however, an overly rapid hydrogenation rate enlarges the particle size and raises the dehydrogenation temperature. A cycling evaluation reveals that the KH-added Mg(NH2)2-2LiH system possesses good reversible hydrogen storage abilities, although the operational temperatures for de-/hydrogenation increase during cycling. Detailed mechanistic investigations indicate that adding KH catalytically decreases the activation energy of the first dehydrogenation step and reduces the enthalpy of desorption during the second dehydrogenation step as a reactant, significantly improving the hydrogen storage properties of Mg(NH2)2-2LiH.

  2. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  3. THE MATHEMATICAL MODEL DEVELOPMENT OF THE ETHYLBENZENE DEHYDROGENATION PROCESS KINETICS IN A TWO-STAGE ADIABATIC CONTINUOUS REACTOR

    Directory of Open Access Journals (Sweden)

    V. K. Bityukov

    2015-01-01

    Full Text Available The article is devoted to the mathematical modeling of the kinetics of ethyl benzene dehydrogenation in a two-stage adiabatic reactor with a catalytic bed functioning on continuous technology. The analysis of chemical reactions taking place parallel to the main reaction of styrene formation has been carried out on the basis of which a number of assumptions were made proceeding from which a kinetic scheme describing the mechanism of the chemical reactions during the dehydrogenation process was developed. A mathematical model of the dehydrogenation process, describing the dynamics of chemical reactions taking place in each of the two stages of the reactor block at a constant temperature is developed. The estimation of the rate constants of direct and reverse reactions of each component, formation and exhaustion of the reacted mixture was made. The dynamics of the starting material concentration variations (ethyl benzene batch was obtained as well as styrene formation dynamics and all byproducts of dehydrogenation (benzene, toluene, ethylene, carbon, hydrogen, ect.. The calculated the variations of the component composition of the reaction mixture during its passage through the first and second stages of the reactor showed that the proposed mathematical description adequately reproduces the kinetics of the process under investigation. This demonstrates the advantage of the developed model, as well as loyalty to the values found for the rate constants of reactions, which enable the use of models for calculating the kinetics of ethyl benzene dehydrogenation under nonisothermal mode in order to determine the optimal temperature trajectory of the reactor operation. In the future, it will reduce energy and resource consumption, increase the volume of produced styrene and improve the economic indexes of the process.

  4. Highly selective oxidative dehydrogenation of ethane with supported molten chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.A.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

    2011-07-01

    Ethene production is one of the most important transformations in chemical industry, given that C{sub 2}H{sub 4} serves as building block for many mass-market products. Besides conventional thermal processes like steam cracking of ethane, ethane can be produced selectively by catalytic processes. One of the classes of catalysts that have been reported in literature as active and highly selective for the oxidative dehydrogenation of ethane is that of supported molten chloride catalysts, containing an alkali chloride overlayer on a solid support. This work deals with fundamental aspects of the catalytic action in latter class of catalysts. Results from kinetic reaction studies are related to observations in detailed characterization and lead to a comprehensive mechanistic understanding. Of fundamental importance towards mechanistic insights is the oxygen storage capacity of the catalysts that has been determined by transient step experiments. (orig.)

  5. Synthesis of carbon-supported copper catalyst and its catalytic performance in methanol dehydrogenation

    Science.gov (United States)

    Shelepova, Ekaterina V.; Vedyagin, Aleksey A.; Ilina, Ludmila Yu.; Nizovskii, Alexander I.; Tsyrulnikov, Pavel G.

    2017-07-01

    Carbon-supported copper catalyst was prepared by incipient wetness impregnation of Sibunit with an aqueous solution of copper nitrate. Copper loading was 5 wt.%. Temperature of reductive pretreatment was varied within a range of 200-400 °C. The samples were characterized by transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron and X-ray absorption spectroscopies. Catalytic activity of the samples was studied in a reaction of methanol dehydrogenation. Silica-based catalyst with similar copper loading was used as a reference. It was found that copper is distributed over the surface of support in the form of metallic and partially oxidized particles of about 12-17 nm in size. Diminished interaction of copper with support was supposed to be responsible for high catalytic activity.

  6. Influence of promoters and oxidants on propane dehydrogenation over chromium-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Shaporeva, N.Yu.; Trushin, D.V.; Gaidai, N.A.; Nekrasov, N.V. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2010-12-30

    Possibilities for increasing the efficiency of supported on SiO{sub 2} chromium-oxide catalysts in propane oxidative dehydrogenation in CO{sub 2} presence are investigated: the introduction of Li, Na, K, Ca in catalysts and the addition of O{sub 2} in the reaction mixture. It was been found that the positive role of K - the increase of the selectivity to propene and stability of catalysts at long-duration tests - appeared at the relation of Cr:K=20. It was shown that the presence of little amount of O{sub 2} (2%) in the reaction mixtures of propane and carbon dioxide resulted in the increase of propene yield and catalyst stability. (orig.)

  7. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2015-03-05

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH) of ethane to ethylene at a relatively low temperature (T<300°C). These catalysts appear to be much more stable than the corresponding composites prepared by other chemical methods; more than 90% of their original intrinsic activity was retained after 50h with time on-stream. Furthermore, the stability was much less affected by the Nb content than in composites prepared by classical "wet" syntheses. These materials, obtained in a solvent-free way, are thus promising green and sustainable alternatives to the current Ni-Nb candidates for the low-temperature ODH of ethane.

  8. Phosphate-modified carbon nanotubes in the oxidative dehydrogenation of isopentanes.

    Science.gov (United States)

    Huang, Rui; Liu, Hong Yang; Zhang, Bing Sen; Sun, Xiao Yan; Liang, Chang Hai; Su, Dang Sheng; Zong, Bao Ning; Rong, Jun Feng

    2014-12-01

    Ketonic/quinonic C=O groups on the surface of a carbon matrix are capable of abstracting hydrogen in C=H bonds from hydrocarbons and enable them to selectively convert into corresponding unsaturated hydrocarbons; this process is the oxidative dehydrogenation (ODH) reaction. However, a variety of inevitable defects or graphene edges and other oxygen-containing groups on the carbon matrix are detrimental to the selective production of alkenes due to their high activity towards overoxidation. Herein, we show that phosphate can not only impede the total oxidation but also cover the selective C=O groups, hence allowing its use as a modulator to defects and oxygen-containing functional groups on the multiwalled carbon nanotubes, regulating the distribution of active sites and related catalytic targets.

  9. Ethanol dehydrogenation on copper catalysts with ytterbium stabilized tetragonal ZrO2 support

    Science.gov (United States)

    Chuklina, S. G.; Pylinina, A. I.; Podzorova, L. I.; Mikhailina, N. A.; Mikhalenko, I. I.

    2016-12-01

    The physicochemical and catalytic properties of Cu-containing crystalline zirconia, obtained via sol-gel synthesis in the presence of Yb3+ ions and polyvinylpyrrolidone, are studied. DTG/DSC, TEM, XRD and BET methods are used to analyze the crystallization, texture, phase uniformity, surface and porosity of ZrO2 nanopowders. It is shown that increasing the copper content (1, 3, and 5 wt % from ZrO2) raises the dehydrogenation activity in the temperature range of 100-400°C and lowers the activation energy of acetaldehyde formation. It is found that the activity of all Cu/ t-ZrO2 catalysts grows under the effects of the reaction medium, due to the migration and redispersion of copper.

  10. Titanocene(III) complexes with 2-phosphinoaryloxide ligands for the catalytic dehydrogenation of dimethylamine borane.

    Science.gov (United States)

    Klahn, Marcus; Hollmann, Dirk; Spannenberg, Anke; Brückner, Angelika; Beweries, Torsten

    2015-07-21

    A study of the dehydrogenation of dimethylamine borane using different titanocene(III) complexes with 2-phosphinoaryloxide ligands is presented. Complexes Cp2Ti(κ(2)-O, P-O-C6H4-PR2) (3a: R = i-Pr, 3b: R = Ph) (Cp = η(5)-cyclopentadienyl) and Cp*2Ti(κ(1)-O-O-C6H4-PR2) (5a: R = i-Pr, 5b: R = Ph) (Cp* = η(5)-pentamethylcyclopentadienyl) were prepared by reactions of the 2-phosphinophenol ligand with different titanocene sources and fully characterised. Their catalytic activity depends on the steric influence of the cyclopentadienyl ligand, the coordination mode of the 2-phosphinoaryloxide ligand and on the used solvent. Complex 3a showed a turnover number of 43.2 in the neat substrate after 24 hours. EPR investigations were used to elucidate the fate of the Ti(III) catalyst.

  11. Concept and progress in coupling of dehydrogenation and hydrogenation reactions through catalysts

    Indian Academy of Sciences (India)

    C V Pramod; C Raghavendra; K Hari Prasad Reddy; G V Ramesh Babu; K S Rama Rao; B David Raju

    2014-03-01

    This review focuses on the importance of coupling of catalytic reactions which involves dehydrogenation and hydrogenation simultaneously and the study of catalytic materials that are designed, adopted and/or modified for these reactions. The special features of these reactions are minimization of H2 utilization and reduction in production cost. Structural and textural properties also play a decisive role in this kind of coupled reactions. This particular review although not comprehensive discusses the significant progress made in the area of coupled reactions and also helps future researchers or engineers to find out the improvements required in areas such as advancements in catalytic material preparation, design of the new reactors and the application of new technologies.

  12. Compensation Effect in the Hydrogenation/Dehydrogenation Kinetics of Metal Hydrides

    DEFF Research Database (Denmark)

    Andreasen, A.; Vegge, T.; Pedersen, Allan Schrøder

    2005-01-01

    The possible existence of a compensation effect, i.e. concurrent changes in activation energy and prefactor, is investigated for the hydrogenation and dehydrogenation kinetics of metal hydrides, by analyzing a series of reported kinetic studies on Mg and LaNi5 based hydrides. For these systems, we...... find a clear linear relation between apparent prefactors and apparent activation energies, as obtained from an Arrhenius analysis, indicating the existence of a compensation effect. Large changes in apparent activation energies in the case of Mg based hydrides are rationalized in terms of a dependency...... analysis rather than a physical phenomenon. In the case of LaNi5 based hydrides, observed scatter in reported apparent activation energies is less pronounced supporting the general experience that LaNi5 is less sensitive toward surface contamination....

  13. Dehydrogenation in lithium borohydride/conventional metal hydride composite based on a mutual catalysis

    DEFF Research Database (Denmark)

    Yu, X.B.; Shi, Qing; Vegge, Tejs;

    2009-01-01

    The dehydrogenation of LiBH4 ball-milled with hydrogenated 40Ti–15Mn–15Cr–30V alloy was investigated. It was found that there is a mutual catalysis between the two hydrides, lowering the temperature of hydrogen release from both hydrides. In the case of 1h milled LiBH4/40Ti–15Mn–15Cr–30V...... with a mass ratio of 1:4, the peak temperatures of 40Ti–15Mn–15Cr–30V and LiBH4 were decreased to 195 and 390°C, respectively, which are 77 and 50°C lower than the respective hydride on its own....

  14. Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2014-06-01

    The sol-gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni-W-O and Ni-Ti-O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction. © 2014 Elsevier B.V. All rights reserved.

  15. Desolvation and dehydrogenation of solvated magnesium salts of dodecahydrododecaborate: relationship between structure and thermal decomposition.

    Science.gov (United States)

    Chen, Xuenian; Liu, Yi-Hsin; Alexander, Anne-Marie; Gallucci, Judith C; Hwang, Son-Jong; Lingam, Hima Kumar; Huang, Zhenguo; Wang, Cong; Li, Huizhen; Zhao, Qianyi; Ozkan, Umit S; Shore, Sheldon G; Zhao, Ji-Cheng

    2014-06-10

    Attempts to synthesize solvent-free MgB12H12 by heating various solvated forms (H2O, NH3, and CH3OH) of the salt failed because of the competition between desolvation and dehydrogenation. This competition has been studied by thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). Products were characterized by IR, solution- and solid-state NMR spectroscopy, elemental analysis, and single-crystal or powder X-ray diffraction analysis. For hydrated salts, thermal decomposition proceeded in three stages, loss of water to form first hexahydrated then trihydrated, and finally loss of water and hydrogen to form polyhydroxylated complexes. For partially ammoniated salts, two stages of thermal decomposition were observed as ammonia and hydrogen were released with weight loss first of 14 % and then 5.5 %. Thermal decomposition of methanolated salts proceeded through a single step with a total weight loss of 32 % with the release of methanol, methane, and hydrogen. All the gaseous products of thermal decomposition were characterized by using mass spectrometry. Residual solid materials were characterized by solid-state (11)B magic-angle spinning (MAS) NMR spectroscopy and X-ray powder diffraction analysis by which the molecular structures of hexahydrated and trihydrated complexes were solved. Both hydrogen and dihydrogen bonds were observed in structures of [Mg(H2O)6B12H12]⋅6 H2O and [Mg(CH3OH)6B12H12]⋅6 CH3OH, which were determined by single-crystal X-ray diffraction analysis. The structural factors influencing thermal decomposition behavior are identified and discussed. The dependence of dehydrogenation on the formation of dihydrogen bonds may be an important consideration in the design of solid-state hydrogen storage materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

    KAUST Repository

    Balasamy, Rabindran J.

    2010-12-20

    A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

  17. Kinetics modeling of ethylbenzene dehydrogenation to styrene over a mesoporous alumina supported iron catalyst

    KAUST Repository

    Hossain, Mohammad M.

    2012-10-01

    The kinetics of ethylbenzene (EB) dehydrogenation over a FeO x-meso-Al 2O 3 catalyst is studied. The models were developed based on physicochemical characterization and a CREC fluidized Riser Simulator data. N 2 adsorption shows that the synthesized FeO x-meso-Al 2O 3 catalyst is mesoporous with pore size between 9 and 35nm. TPR profile indicates that iron on meso-Al 2O 3 forms easily reducible nanostructured crystals which is confirmed by TEM image. NH 3- and CO-TPD analysis, respectively reveals the availability of both acidic and basic sites. The dehydrogenation of ethylbenzene on FeO x-meso-Al 2O 3 catalyst mainly gives styrene (∼99%) while a small amount of benzene, toluene and coke are also detected. Based on the experimental observations two Langmuir-Hinshelwood type kinetics models are formulated. The possible catalyst deactivation is expressed as function of EB conversion. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one type site Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the physical constraints. The activation energy for the formation of styrene (80kJ/mol) found to be significantly lower than that of the undesired products benzene (144kJ/mol) and toluene (164kJ/mol). The estimated heat of adsorptions of EB and ST are found to be 55kJ/mol and 19kJ/mol, respectively. © 2012 Elsevier B.V.

  18. A study of the isobutane dehydrogenation in a porous membrane catalytic reactor: design, use and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Casanave, D.

    1996-01-26

    The aim of this study was to set up and model a catalytic fixed-bed membrane reactor for the isobutane dehydrogenation. The catalyst, developed at Catalysis Research Institute (IRC), was a silicalite-supported Pt-based catalyst. Their catalytic performances (activity, selectivity, stability) where found better adapted to the membrane reactor, when compared with commercial Pt or Cr based catalysts. The kinetic study of the reaction has been performed in a differential reactor and led to the determination of a kinetic law, suitable when the catalyst is used near thermodynamic equilibrium. The mass transfer mechanisms were determined in meso-porous and microporous membranes through both permeability and gas mixtures (iC{sub 4}/H{sub 2}/N{sub 2}) separation measurements. For the meso-porous {gamma}-alumina, the mass transfer is ensured by a Knudsen diffusion mechanism which can compete with surface diffusion for condensable gas like isobutane. The resulting permselectivity H{sub 2}/iC4 of this membrane is low ({approx} 4). For the microporous zeolite membrane, molecular sieving occurs due to steric hindrance, leading to higher permselectivity {approx}14. Catalyst/membrane associations were compared in terms of isobutane dehydrogenation performances, for both types of membranes (meso-porous and microporous) and for two different reactor configurations (co-current and counter-current sweep gas flow). The best experimental results were obtained with the zeolite membrane, when sweeping the outer compartment in a co-current flow. The equilibrium displacement observed with the {gamma}-alumina membrane was lower and mainly due to a dilution effect of the reaction mixture by the sweep gas. A mathematical model was developed, which correctly describes all the experimental results obtained with the zeolite membrane, when the co-current mode is used. (Abstract Truncated)

  19. Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

    KAUST Repository

    Shaikh Ali, Anaam

    2017-01-18

    Liquid organic chemical hydrides are effective hydrogen storage media for easy and safe transport. The chemical couple of methylcyclohexane (MCH) and toluene (TOL) has been considered one of the feasible cycles for a hydrogen carrier, but the selective dehydrogenation of MCH to TOL has been reported using only Pt-based noble metal catalysts. This study reports MCH dehydrogenation to TOL using supported NiZn as a selective, non-noble-metal catalyst. A combined experimental and computational study was conducted to provide insight into the site requirements and reaction mechanism for MCH dehydrogenation to TOL, which were compared with those for cyclohexane (CH) dehydrogenation to benzene (BZ). The kinetic measurements carried out at 300-360°C showed an almost zero order with respect to MCH pressure in the high-pressure region (≥10 kPa) and nearly a positive half order with respective to H pressure (≤40 kPa). These kinetic data for the dehydrogenation reaction paradoxically indicate that hydrogenation of a strongly chemisorbed intermediate originating from TOL is the rate-determining step. Density functional theory (DFT) calculation confirms that the dehydrogenated TOL species at the aliphatic (methyl) position group (CHCH) were strongly adsorbed on the surface, which must be hydrogenated to desorb as TOL. This hydrogen-assisted desorption mechanism explains the essential role of excess H present in the feed in maintaining the activity of the metallic surface for hydrogenation. The rate of the CH to BZ reaction was less sensitive to H pressure than that of MCH to TOL, which can be explained by the absence of a methyl group in the structure, which in turn reduces the binding energy of the adsorbed species. DFT suggests that the improved TOL selectivity by adding Zn to Ni was due to Zn atoms preferentially occupying low-coordination sites on the surface (the corner and edge sites), which are likely the unselective sites responsible for the C-C dissociation of the

  20. Bulk binary ZrO2-based oxides as highly active alternative-type catalysts for non-oxidative isobutane dehydrogenation.

    Science.gov (United States)

    Otroshchenko, Tatyana; Radnik, Jörg; Schneider, Matthias; Rodemerck, Uwe; Linke, David; Kondratenko, Evgenii V

    2016-06-21

    Bulk binary ZrO2-based oxides efficiently catalyse non-oxidative dehydrogenation of isobutane to isobutylene. Their activity strongly depends on the kind of second metal oxide. So designed CrZrOx showed superior activity to industrially relevant catalysts with supported Pt or CrOx species. It was also stable under alternating dehydrogenation and oxidative regeneration cycles over ca. 110 h under different reaction conditions between 550 and 600 °C.

  1. Vitamin Deficiency Anemia

    Science.gov (United States)

    ... are unique to specific vitamin deficiencies. Folate-deficiency anemia risk factors include: Undergoing hemodialysis for kidney failure. ... the metabolism of folate. Vitamin B-12 deficiency anemia risk factors include: Lack of intrinsic factor. Most ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... at highest risk for iron-deficiency anemia. Outlook Doctors usually can successfully treat iron-deficiency anemia. Treatment ... poor skin tone, dizziness, and depression. After her doctor diagnosed her with iron-deficiency anemia, Susan got ...

  3. Effect of Porphyrin Ligands on the Regioselective Dehydrogenation versus Epoxidation of Olefins by Oxoiron(IV) Mimics of Cytochrome P450

    Science.gov (United States)

    Kumar, Devesh; Tahsini, Laleh; Visser, Sam P. De; Kang, Hye Yeon; Kim, Soo Jeong; Nam, Wonwoo

    2009-08-01

    The cytochromes P450 are versatile enzymes involved in various catalytic oxidation reactions, such as hydroxylation, epoxidation and dehydrogenation. In this work, we present combined experimental and theoretical studies on the change of regioselectivity in cyclohexadiene oxidation (i.e., epoxidation vs dehydrogenation) by oxoiron(IV) porphyrin complexes bearing different porphyrin ligands. Our experimental results show that meso-substitution of the porphyrin ring with electron-withdrawing substituents leads to a regioselectivity switch from dehydrogenation to epoxidation, affording the formation of epoxide as a major product. In contrast, electron-rich iron porphyrins are shown to produce benzene resulting from the dehydrogenation of cyclohexadiene. Density functional theory (DFT) calculations on the regioselectivity switch of epoxidation vs dehydrogenation have been performed using three oxoiron(IV) porphyrin oxidants with hydrogen atoms, phenyl groups, and pentachlorophenyl (ArCl5) groups on the meso-position. The DFT studies show that the epoxidation reaction by the latter catalyst is stabilized because of favorable interactions of the substrate with halogen atoms of the meso-ligand as well as with pyrrole nitrogen atoms of the porphyrin macrocycle. Hydrogen abstraction transition states, in contrast, have a substrate-binding orientation further away from the porphyrin pyrrole nitrogens, and they are much less stabilized. Finally, the regioselectivity of dehydrogenation versus hydroxylation is rationalized using thermodynamic cycles.

  4. Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

    Directory of Open Access Journals (Sweden)

    Shujun Qiu

    2017-01-01

    Full Text Available Doping with additives in a Li-Mg-N-H system has been regarded as one of the most effective methods of improving hydrogen storage properties. In this paper, we prepared Li3AlH6 and evaluated its effect on the dehydrogenation properties of 2LiNH2-MgH2. Our studies show that doping with Li3AlH6 could effectively lower the dehydrogenation temperatures and increase the hydrogen content of 2LiNH2-MgH2. For example, 2LiNH2-MgH2-0.1Li3AlH6 can desorb 6.43 wt % of hydrogen upon heating to 300 °C, with the onset dehydrogenation temperature at 78 °C. Isothermal dehydrogenation testing indicated that 2LiNH2-MgH2-0.1Li3AlH6 had superior dehydrogenation kinetics at low temperature. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of the thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the fact that doping with Li3AlH6 could improve the heat transfer for solid–solid reaction.

  5. Direct and Efficient Dehydrogenation of Tetrahydroquinolines and Primary Amines Using Corona Discharge Generated on Ambient Hydrophobic Paper Substrate

    Science.gov (United States)

    Davis, Kathryn M.; Badu-Tawiah, Abraham K.

    2016-10-01

    The exposure of an aqueous-based liquid drop containing amines and graphite particles to plasma generated by a corona discharge results in heterogeneous aerobic dehydrogenation reactions. This green oxidation reaction occurring in ambient air afforded the corresponding quinolines and nitriles from tetrahydroquinolines and primary amines, respectively, at >96% yields in less than 2 min of reaction time. The accelerated dehydrogenation reactions occurred on the surface of a low energy hydrophobic paper, which served both as container for holding the reacting liquid drop and as a medium for achieving paper spray ionization of reaction products for subsequent characterization by ambient mass spectrometry. Control experiments indicate superoxide anions (O2 •-) are the main reactive species; the presence of graphite particles introduced heterogeneous surface effects, and enabled the efficient sampling of the plasma into the grounded analyte droplet solution.

  6. Direct and Efficient Dehydrogenation of Tetrahydroquinolines and Primary Amines Using Corona Discharge Generated on Ambient Hydrophobic Paper Substrate

    Science.gov (United States)

    Davis, Kathryn M.; Badu-Tawiah, Abraham K.

    2017-04-01

    The exposure of an aqueous-based liquid drop containing amines and graphite particles to plasma generated by a corona discharge results in heterogeneous aerobic dehydrogenation reactions. This green oxidation reaction occurring in ambient air afforded the corresponding quinolines and nitriles from tetrahydroquinolines and primary amines, respectively, at >96% yields in less than 2 min of reaction time. The accelerated dehydrogenation reactions occurred on the surface of a low energy hydrophobic paper, which served both as container for holding the reacting liquid drop and as a medium for achieving paper spray ionization of reaction products for subsequent characterization by ambient mass spectrometry. Control experiments indicate superoxide anions (O2 •-) are the main reactive species; the presence of graphite particles introduced heterogeneous surface effects, and enabled the efficient sampling of the plasma into the grounded analyte droplet solution.

  7. Porous AgPt@Pt Nanooctahedra as an Efficient Catalyst toward Formic Acid Oxidation with Predominant Dehydrogenation Pathway.

    Science.gov (United States)

    Jiang, Xian; Yan, Xiaoxiao; Ren, Wangyu; Jia, Yufeng; Chen, Jianian; Sun, Dongmei; Xu, Lin; Tang, Yawen

    2016-11-16

    For direct formic acid fuel cells (DFAFCs), the dehydrogenation pathway is a desired reaction pathway, to boost the overall cell efficiency. Elaborate composition tuning and nanostructure engineering provide two promising strategies to design efficient electrocatalysts for DFAFCs. Herein, we present a facile synthesis of porous AgPt bimetallic nanooctahedra with enriched Pt surface (denoted as AgPt@Pt nanooctahedra) by a selective etching strategy. The smart integration of geometric and electronic effect confers a substantial enhancement of desired dehydrogenation pathway as well as electro-oxidation activity for the formic acid oxidation reaction (FAOR). We anticipate that the obtained nanocatalyst may hold great promises in fuel cell devices, and furthermore, the facile synthetic strategy demonstrated here can be extendable for the fabrication of other multicomponent nanoalloys with desirable morphologies and enhanced electrocatalytic performances.

  8. Facile synthesis of TiN decorated graphene and its enhanced catalytic effects on dehydrogenation performance of magnesium hydride

    Science.gov (United States)

    Wang, Ying; Li, Li; An, Cuihua; Wang, Yijing; Chen, Chengcheng; Jiao, Lifang; Yuan, Huatang

    2014-05-01

    TiN@rGO nanohybrids were successfully synthesized by a simple ``urea glass'' technique. Experimental results demonstrated that TiN nanocrystals, with an average particle size of 20 nm, were uniformly anchored onto highly reduced graphene nanosheets. The as-synthesized TiN@rGO nanohybrids showed a porous planar-like structure, which had a large surface area of 177 m2 g-1. More importantly, the as-prepared TiN@rGO hybrids showed enhanced catalytic effects on the dehydrogenation of MgH2. The dehydrogenation thermodynamics and kinetics of the MgH2-TiN@rGO composites were systematically investigated and some significant improvements were confirmed. It was found that the 10 wt% TiN@rGO doped MgH2 sample started to release hydrogen at about 167 °C, and roughly 6.0 wt% hydrogen was released within 18 min when isothermally heated to 300 °C. In contrast, the onset dehydrogenation temperature of the pure MgH2 sample was about 307 °C, and only 3.5 wt% hydrogen was released even after 120 min of heating under identical conditions. In addition, the catalytic mechanism of TiN@rGO on the dehydrogenation of MgH2 was discussed using the Johnson-Mehl-Avrami (JMA) model and X-ray diffraction equipment.TiN@rGO nanohybrids were successfully synthesized by a simple ``urea glass'' technique. Experimental results demonstrated that TiN nanocrystals, with an average particle size of 20 nm, were uniformly anchored onto highly reduced graphene nanosheets. The as-synthesized TiN@rGO nanohybrids showed a porous planar-like structure, which had a large surface area of 177 m2 g-1. More importantly, the as-prepared TiN@rGO hybrids showed enhanced catalytic effects on the dehydrogenation of MgH2. The dehydrogenation thermodynamics and kinetics of the MgH2-TiN@rGO composites were systematically investigated and some significant improvements were confirmed. It was found that the 10 wt% TiN@rGO doped MgH2 sample started to release hydrogen at about 167 °C, and roughly 6.0 wt% hydrogen was released

  9. Synthesis and applications of mesoporous Cu-Zn-Al2O3 catalyst for dehydrogenation of 2-butanol

    Institute of Scientific and Technical Information of China (English)

    Deren Fang; Wanzhong Ren; Zhongmin Liu; Xiufeng Xu; Lei Xu; Hongying L(u); Weiping Liao; Huimin Zhang

    2009-01-01

    A series of mesoporous Cu-Zn-Al2O3 materials have been synthesized at ambient temperature and their structure was characterized by XRD, N2 physical adsorption and TPR techniques. Their catalytic applications for the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were evaluated in a fixed-bed flow reactor at atmospheric pressure. It is demonstrated from the XRD patterns that both the as-synthesized samples and calcined samples have the typical XRD patterns of meso-structured materials and the results of N2O chemical adsorption showed that Cu was embedded in the framework of the mesoporous materials and homogeneously dispersed in the mesoporous Cu-Zn-Al2O3 materials. The catalytic activity of 2-hntanol dehydrogenation was varied in the order of CZA(10)

  10. Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites

    KAUST Repository

    Tope, Balkrishna B.

    2011-11-01

    Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni2+ in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co3+/Co2+ in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe3+ active sites by forming Fe3+-O-Co 3+/2+(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and π-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe3+ acid sites via π-bonding and the dehydrogenation was initiated by α-H+ abstraction from ethyl group on Mg2+-O2- basic sites, followed by C-O-Mg bond formation. The α-H+ abstraction by O2-(-Mg 2+) was likely followed by β-H abstraction, leading to the formations of styrene and H2. Such catalytic mechanism by the Fe 3+ acid-O2-(-Mg2+) base couple and the Fe 3+/Fe2+ reduction-oxidation cycle was further assisted by Co3+/Co2+, leading to a good catalytic activity for the dehydrogenation of ethylbenzene. © 2011 Elsevier B.V. All rights reserved.

  11. Highly practical synthesis of nitriles and heterocycles from alcohols under mild conditions by aerobic double dehydrogenative catalysis.

    Science.gov (United States)

    Yin, Weiyu; Wang, Chengming; Huang, Yong

    2013-04-19

    A mild, aerobic, catalytic process for obtaining nitriles directly from alcohols and aqueous ammonia is described. The reaction proceeds via a dehydrogenation cascade mediated by catalytic CuI, bpy, and TEMPO in the presence of O2. The substrate scope is broad including various functionalized aromatic and aliphatic alcohols. This protocol enabled the one-pot synthesis of various biaryl heterocycles directly from commercially available alcohols.

  12. Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples Univ. (Italy). Dept. of Chemistry

    2011-07-01

    The oxidative dehydrogenation (ODH) of propane has been investigated by using many different vanadia based catalysts, prepared by grafting technique and containing variable amounts of active phase supported on SiO{sub 2} previously coated, by grafting in three different steps, with multilayer of TiO{sub 2}. A depth catalytic screening, conducted in a temperature range of 400-600 C, at atmospheric pressure and in a range of residence time W/F=0.08-0.33 ghmol{sub -1}, has shown that the vanadium oxide catalysts on TiO{sub 2}-SiO{sub 2} support, prepared by grafting have good performances in the ODH of propane. In particular, a preliminary study has demonstrated that higher selectivities can be obtained employing catalysts having a well dispersed active phase that can be achieved with a V{sub 2}O{sub 5} content lower than 10%{sub w}t. It is well known that, in the case of redox catalysts, an increase of the selectivity can be achieved not only by using an adequate catalytic system but also via engineering routes like decoupling catalytic steps of reduction and re-oxidation. In fact it has been observed that by operating in dehydrogenating mode, on the same catalysts, a higher selectivity is obtained although the catalyst is poisoned by the formation of coke on the surface. As consequence of the results obtained in dehydrogenation, in this work has been explored the possibility to feed low amounts of oxygen, below the stoichiometric level with the aim to keep clean the surface from coke but maintaining high the selectivity, because, dehydrogenation reaction prevails. In this work, the behavior of catalysts containing different amounts of V2O5 has been studied in the propane-propene reaction by using different ratios C{sub 3}H{sub 8}/O{sub 2} included in the range 0-2. (orig.)

  13. Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

    Directory of Open Access Journals (Sweden)

    Kuppusamy Bharathimohan

    2014-12-01

    Full Text Available Herein, we describe a one-pot protocol for the synthesis of a novel series of polycyclic triazole derivatives. Transition metal-catalyzed decarboxylative CuAAC and dehydrogenative cross coupling reactions are combined in a single flask and achieved good yields of the respective triazoles (up to 97% yield. This methodology is more convenient to produce the complex polycyclic molecules in a simple way.

  14. Effects of Al{sub 2}O{sub 3} phase and Cl component on dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Liu, Changcheng; Ma, Aizeng; Rong, Junfeng; Da, Zhijian, E-mail: dazhijianripp@163.com; Zheng, Aiguo; Qin, Ling

    2016-04-15

    Graphical abstract: - Highlights: • Comparative study of Al{sub 2}O{sub 3} phase on dehydrogenation of propane was implemented. • Pore structures and acid properties of Pt-Al{sub 2}O{sub 3} are correlated to the activities. • Pt-θ-Al{sub 2}O{sub 3} with abundant Cl content shows the highest activity and stability. - Abstract: The effects of two Al{sub 2}O{sub 3} phases, γ- and θ-Al{sub 2}O{sub 3}, and Cl component on the performances of Pt-Al{sub 2}O{sub 3} catalysts in the dehydrogenation of propane were investigated in this work. The catalysts were systematically characterized by various techniques, such as scanning transmission electron microscopy (STEM), temperature-programmed desorption with ammonia as probe molecules (NH{sub 3}-TPD) and temperature-programmed oxidation (TPO). The characterizations and catalytic results show that: (i) the pore structures and acid properties of the two Al{sub 2}O{sub 3} phases can change the quantity, location and property of the carbon deposition, (ii) the existence of Cl plays a significant role on the agglomeration of Pt particles and carbon deposition, which further influence the catalytic performances of Pt-Al{sub 2}O{sub 3} catalysts with different support phases for propane dehydrogenation.

  15. Towards understanding a mechanism for reversible hydrogen storage: theoretical study of transition metal catalysed dehydrogenation of sodium alanate.

    Science.gov (United States)

    Ljubić, Ivan; Clary, David C

    2010-04-28

    On the basis of density functional theory and coupled-cluster CCSD(T) calculations we propose a mechanism of the dehydrogenation of transition metal doped sodium alanate. Insertion of two early 3d-transition metals, scandium and titanium, both of which are promising catalysts for reversible hydrogen storage in light metal hydrides, is compared. The mechanism is deduced from studies on the decomposition of a model system consisting of one transition metal atom and two NaAlH(4) units. Subsequently, the significance of such minimal cluster model systems to the real materials is tested by embedding the systems into the surface of the NaAlH(4) crystal. It is found that the dehydrogenation proceeds via breaking of the bridge H-Al bond and consequent formation of intermediate coordination compounds in which the H(2) molecule is side-on (eta(2)-) bonded to the transition metal centre. The total barrier to the H(2) release is thus dependent upon both the strength of the Al-H bond to be broken and the depth of the coordinative potential. The analogous mechanism applies for the recognized three successive dehydrogenation steps. The gas-phase model structures embedded into the surface of the NaAlH(4) crystal exhibit an unambiguous kinetic stability and their general geometric features remain largely unchanged.

  16. Ultrasound promoted catalytic liquid-phase dehydrogenation of isopropanol for Isopropanol-Acetone-Hydrogen chemical heat pump.

    Science.gov (United States)

    Xu, Min; Xin, Fang; Li, Xunfeng; Huai, Xiulan; Liu, Hui

    2015-03-01

    The apparent kinetic of the ultrasound assisted liquid-phase dehydrogenation of isopropanol over Raney nickel catalyst was determined in the temperature range of 346-353 K. Comparison of the effects of ultrasound and mechanical agitation on the isopropanol dehydrogenation was investigated. The ultrasound assisted dehydrogenation rate was significantly improved when relatively high power density was used. Moreover, the Isopropanol-Acetone-Hydrogen chemical heat pump (IAH-CHP) with ultrasound irradiation, in which the endothermic reaction is exposure to ultrasound, was proposed. A mathematical model was established to evaluate its energy performance in term of the coefficient of performance (COP) and the exergy efficiency, into which the apparent kinetic obtained in this work was incorporated. The operating performances between IAH-CHP with ultrasound and mechanical agitation were compared. The results indicated that the superiority of the IAH-CHP system with ultrasound was present even if more than 50% of the power of the ultrasound equipment was lost. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Genotypic and phenotypic spectrum of pyridoxine-dependent epilepsy (ALDH7A1 deficiency)

    DEFF Research Database (Denmark)

    Mills, Philippa B; Footitt, Emma J; Mills, Kevin A

    2010-01-01

    Pyridoxine-dependent epilepsy was recently shown to be due to mutations in the ALDH7A1 gene, which encodes antiquitin, an enzyme that catalyses the nicotinamide adenine dinucleotide-dependent dehydrogenation of l-alpha-aminoadipic semialdehyde/L-Delta1-piperideine 6-carboxylate. However, whilst t...... to pyridoxine. These findings support the use of biochemical and DNA tests for antiquitin deficiency and a clinical trial of pyridoxine in infants and children with epilepsy across a broad range of clinical scenarios.......Pyridoxine-dependent epilepsy was recently shown to be due to mutations in the ALDH7A1 gene, which encodes antiquitin, an enzyme that catalyses the nicotinamide adenine dinucleotide-dependent dehydrogenation of l-alpha-aminoadipic semialdehyde/L-Delta1-piperideine 6-carboxylate. However, whilst...... with suspected or clinically proven pyridoxine-dependent epilepsy and to characterize further the phenotypic spectrum of antiquitin deficiency. Urinary L-alpha-aminoadipic semialdehyde concentration was determined by liquid chromatography tandem mass spectrometry. When this was above the normal range, DNA...

  18. Improvement in Hydrogention and Dehydrogenation Characteristics of Magnesium by Addition of Titanium (III Chloride via Transformation-Accompanying Milling

    Directory of Open Access Journals (Sweden)

    Myoung Youp SONG

    2017-08-01

    Full Text Available A specimen consisting of 90 wt.% Mg and 10 wt.% TiCl3 (called 95 Mg + 10 TiCl3 was made by transformation-accompanying milling, and its hydrogenation and dehydrogenation features were checked. The activation of 95 Mg + 10 TiCl3 was not demanded. 95 Mg + 10 TiCl3 revealed an useful hydrogenation-dehydrogenation capacity (the quantity of hydrogen absorbed in 60 min of about 5.6 wt.%. At n = 1, the specimen absorbed 4.06 wt.% of hydrogen in 5 min, 5.09 wt.% of hydrogen in 10 min, and 5.59 wt.% of hydrogen in 60 min at 593 K in 1.2 MPa H2. At n = 1, the specimen desorbed 0.47 wt.% of hydrogen in 2.5 min, 3.81 wt.% of hydrogen in 30 min, and 5.20 wt.% of hydrogen in 60 min at 593 K in 0.1 MPa H2. The XRD pattern of 95 Mg + 10TiCl3 dehydrogenated at the 4th hydrogenation-dehydrogenation cycle included Mg, β-MgH2, MgO, and a small amount of TiH1.924 phases. The P (equilibrium hydrogen pressure-C (composition-T (temperature curve at 593 K revealed an equilibrium plateau pressure at about 0.25 MPa. 95 Mg + 10 TiCl3 had a higher early hydrogenation rate and a larger amount of hydrogen absorbed in 60 min than Mg, 90 Mg + 10 Fe2O3, 90 Mg + 10 MnO, and 90 Mg + 10 TaF5, the hydrogenation and dehydrogenation features of which were before informed of.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16375

  19. Hydrogen liberation from the hydrolytic dehydrogenation of dimethylamine-borane at room temperature by using a novel ruthenium nanocatalyst.

    Science.gov (United States)

    Caliskan, Salim; Zahmakiran, Mehmet; Durap, Feyyaz; Özkar, Saim

    2012-04-28

    Herein we report the discovery of an in situ generated, highly active nanocatalyst for the room temperature dehydrogenation of dimethylamine-borane in water. The new catalyst system consisting of ruthenium(0) nanoparticles stabilized by the hydrogenphosphate anion can readily and reproducibly be formed under in situ conditions from the dimethylamine-borane reduction of a ruthenium(III) precatalyst in tetrabutylammonium dihydrogenphosphate solution at 25 ± 0.1 °C. These new water dispersible ruthenium nanoparticles were characterized by using a combination of advanced analytical techniques. The results show the formation of well-dispersed ruthenium(0) nanoparticles of 2.9 ± 0.9 nm size stabilized by the hydrogenphosphate anion in aqueous solution. The resulting ruthenium(0) nanoparticles act as a highly active catalyst in the generation of 3.0 equiv. of H(2) from the hydrolytic dehydrogenation of dimethylamine-borane with an initial TOF value of 500 h(-1) at 25 ± 0.1 °C. Moreover, they provide exceptional catalytic lifetime (TTO = 11,600) in the same reaction at room temperature. The work reported here also includes the following results; (i) monitoring the formation kinetics of the in situ generated ruthenium nanoparticles, by using the hydrogen generation from the hydrolytic dehydrogenation of dimethylamine-borane as a catalytic reporter reaction, shows that sigmoidal kinetics of catalyst formation and concomitant dehydrogenation fits well to the two-step, slow nucleation and then autocatalytic surface growth mechanism, A → B (rate constant k(1)) and A + B → 2B (rate constant k(2)), in which A is RuCl(3)·3H(2)O and B is the growing, catalytically active Ru(0)(n) nanoclusters. (ii) Hg(0) poisoning coupled with activity measurements after solution infiltration demonstrates that the in situ generated ruthenium(0) nanoparticles act as a kinetically competent heterogeneous catalyst in hydrogen generation from the hydrolytic dehydrogenation of dimethylamine

  20. Carnitine Deficiency and Pregnancy

    OpenAIRE

    Anouk de Bruyn; Yves Jacquemyn; Kristof Kinget; François Eyskens

    2015-01-01

    We present two cases of carnitine deficiency in pregnancy. In our first case, systematic screening revealed L-carnitine deficiency in the first born of an asymptomatic mother. In the course of her second pregnancy, maternal carnitine levels showed a deficiency as well. In a second case, a mother known with carnitine deficiency under supplementation was followed throughout her pregnancy. Both pregnancies had an uneventful outcome. Because carnitine deficiency can have serious complications, su...

  1. Synergistic effect between Sn and K promoters on supported platinum catalyst for isobutane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Yiwei Zhang; Yuming Zhou; Lihui Wan; Mengwei Xue; Yongzheng Duan; Xuan Liu

    2011-01-01

    Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction.

  2. Dehydrogenative silane coupling on silicon surfaces via early transition metal catalysis.

    Science.gov (United States)

    Li, Yun-Hui; Buriak, Jillian M

    2006-02-01

    Derivatization of silicon surfaces is an area of intense interest due to the centrality of silicon in the microelectronics industry and because of potential promise for a myriad of other applications. In this paper, we investigate the feasibility of Si-Si bond formation directly on the surface to contrast with the more widely studied Si-C and Si-O bond forming reactions. Functionalization of hydride-terminated silicon surfaces with silanes is carried out via early transition metal mediated dehydrogenative silane coupling reactions. Zirconocene and titanocene catalyst systems were evaluated for heterocoupling of a molecular silane, RSiH3, with a surface Si-H group on Si(s). The zirconocene catalysts proved to be much more reactive than the titanium system, and so the former was examined exclusively. The silanes, aromatic or aliphatic, are bonded to the silicon surface through direct Si-Si bonds, although the level of incorporation of the trihydroarylsilanes was substantially higher than that of the aliphatic silanes. The reaction proceeds on nanocrystalline hydride-terminated porous silicon surfaces, as well as flat Si(100)-H(x) and Si(111)-H interfaces. The reactions were studied by a variety of techniques, including FTIR, SIMS, and XPS.

  3. Technique for regenerating the immobile hydrocarbon dehydrogenation layer of the catalyzer

    Energy Technology Data Exchange (ETDEWEB)

    Abayev, G.N.; Kuznetsov, Yu.I.; Ostrovskiy, N.M.; Rumyantsev, V.G.; Slin' ko, M.G.

    1980-01-25

    An improved regeneration method is claimed. To reduce regeneration time and to decrease use of 0/sub 2/-containing gas, regeneration is carried out with initial volume rate of 120-8000 hour/sup -1/, and a gradual decrease toward end of regeneration by 1.7136 times. For example, dehyrogenation of isoamilenes into isoprene is carried out in an adiabatic reactors at a temp. of 640/sup 0/C, volume feed rate of raw material of 150 hour/sup -1/ and mol. dilution of raw material with water vapor 1:20, above Ca-Ni-phosphate-catalyzer in the mixture with granulated A1/sub 2/0/sub 3/. Overall cycle time is 30 min., including: dehydrogenation, 15 min, steam blowing 1.5 min, regeneration with steam/air mixture, 12 min, steam blowing 1.5 min; air feed rate at Pr 120 hour/sup -1/. Coke baking comprised 6.5 min, air used 15 m/sup 4/. Carrying regeneration in the same conditions, but with initial air feed rate at 220 hour/sup -1/, and decreasing it to the end of the regeneration to 30 hour/sup -1/, the coke baking time comprised 5.5 min, and air use 11.5 m/sup 3/.

  4. Catalytic propane dehydrogenation over In₂O₃–Ga₂O₃ mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Shuai; Gil, Laura Briones; Subramanian, Nachal; Sholl, David S.; Nair, Sankar; Jones, Christopher W.; Moore, Jason S.; Liu, Yujun; Dixit, Ravindra S.; Pendergast, John G. (Dow); (GIT)

    2015-08-26

    We have investigated the catalytic performance of novel In₂O₃–Ga₂O₃ mixed oxides synthesized by the alcoholic-coprecipitation method for propane dehydrogenation (PDH). Reactivity measurements reveal that the activities of In₂O₃–Ga₂O₃ catalysts are 1–3-fold (on an active metal basis) and 12–28-fold (on a surface area basis) higher than an In₂O₃–Al₂O₃ catalyst in terms of C₃H₈ conversion. The structure, composition, and surface properties of the In₂O₃–Ga₂O₃ catalysts are thoroughly characterized. NH₃-TPD shows that the binary oxide system generates more acid sites than the corresponding single-component catalysts. Raman spectroscopy suggests that catalysts that produce coke of a more graphitic nature suppress cracking reactions, leading to higher C₃H₆ selectivity. Lower reaction temperature also leads to higher C₃H₆ selectivity by slowing down the rate of side reactions. XRD, XPS, and XANES measurements, strongly suggest that metallic indium and In₂O₃ clusters are formed on the catalyst surface during the reaction. The agglomeration of In₂O₃ domains and formation of a metallic indium phase are found to be irreversible under O₂ or H₂ treatment conditions used here, and may be responsible for loss of activity with increasing time on stream.

  5. Molecular lifting, twisting, and curling during metal-assisted polycyclic hydrocarbon dehydrogenation

    Science.gov (United States)

    Curcio, Davide; Omiciuolo, Luca; Pozzo, Monica; Lacovig, Paolo; Lizzit, Silvano; Jabeen, Naila; Petaccia, Luca; Alfe, Dario; Baraldi, Alessandro

    Through a combined experimental and theoretical approach, we show that coronene molecules adsorbed on Ir(111) undergo major changes in conformation during the dissociation process, which brings the molecules from a flat configuration to graphene, through a series of exotic configurations. The complex reaction path involves the tilting upwards of the molecules, which subsequently experience a rotation with respect to the surface. During the lifting, the C-C strain is initially relieved, while as the dehydrogenation proceeds, the molecules experience a progressive increase in the average interatomic distance, and gradually settle to form peculiar dome shaped nanographenes. This reaction mechanism can provide new insight into the surface assisted break-up mechanism of PAHs, which has been demonstrated to be an effective strategy for the synthesis of low dimensional carbon-based materials. Beside the peculiarity of the reaction pathway, using these processes we envisage the unique possibility of creating new structures with different functionalities by encapsulating single atoms below the carbon dome.

  6. Effect of surface phosphorus on the oxidative dehydrogenation of ethane: A first-principles investigation

    Science.gov (United States)

    Maiti, Amitesh; Govind, Niranjan; Kung, Paul; King-Smith, Dominic; Miller, James E.; Zhang, Conrad; Whitwell, George

    2002-11-01

    Oxidative dehydrogenation (ODH) of small-chain alkanes has the potential to displace thermal cracking as the preferred method of light olefin production. Many heterogeneous catalysts for the ODH reaction have been discussed in the literature, including oxides, vanadates, and phosphates of rare earth and transition metals. Our experiments and the literature indicate that for most of these catalysts, including silica gel and alumina, a phosphorus-enriched surface enhances the ODH yield of ethane to ethylene. To understand the role of P, the ODH reactions were simulated on a silica surface, with and without P, using the density functional theory code DMol3 in a periodic supercell. Optimized structures for all intermediates as well as transition states were obtained for full catalytic cycles. The simulations reveal that activation barriers for the rate-limiting steps are lowered by ˜10 kcal/mol in the presence of P. The decrease results from a transition state in which the P atom remains quasi-5-valent and fourfold coordinated.

  7. Control of Reactivity and Regioselectivity for On-Surface Dehydrogenative Aryl-Aryl Bond Formation.

    Science.gov (United States)

    Kocić, Nemanja; Liu, Xunshan; Chen, Songjie; Decurtins, Silvio; Krejčí, Ondřej; Jelínek, Pavel; Repp, Jascha; Liu, Shi-Xia

    2016-05-04

    Regioselectivity is of fundamental importance in chemical synthesis. Although many concepts for site-selective reactions are well established for solution chemistry, it is not a priori clear whether they can easily be transferred to reactions taking place on a metal surface. A metal will fix the chemical potential of the electrons and perturb the electronic states of the reactants because of hybridization. Additionally, techniques to characterize chemical reactions in solution are generally not applicable to on-surface reactions. Only recent developments in resolving chemical structures by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) paved the way for identifying individual reaction products on surfaces. Here we exploit a combined STM/AFM technique to demonstrate the on-surface formation of complex molecular architectures built up from a heteroaromatic precursor, the tetracyclic pyrazino[2,3-f][4,7]phenanthroline (pap) molecule. Selective intermolecular aryl-aryl coupling via dehydrogenative C-H activation occurs on Au(111) upon thermal annealing under ultrahigh vacuum (UHV) conditions. A full atomistic description of the different reaction products based on an unambiguous discrimination between pyrazine and pyridine moieties is presented. Our work not only elucidates that ortho-hydrogen atoms of the pyrazine rings are preferentially activated over their pyridine equivalents, but also sheds new light onto the participation of substrate atoms in metal-organic coordination bonding during covalent C-C bond formation.

  8. Defective fullerenes as catalyst for dehydrogenation from NaAlH4 clusters

    Science.gov (United States)

    Agnihotri, Deepak; Meenakshi, Sharma, Hitesh

    2015-06-01

    In the present work we have shown that C60 with defect can act as an effective catalyst for dehydrogenation from NaAlH4 clusters. The investigations have been performed using density functional theory calculations. The NaAlH4 interact weakly with the C60 with vacancy defect with binding energy of 0.26eV. The hydrogen release energy shows sharp decrease in magnitude from 3.82eV in NaAlH4 to 1.97 eV in C59NaAlH4 and 1.63eV in C58BNaAlH4. The results may be explained on the basis of change in the net charge at Na and AlH4 resulting in weaker ionic interaction due to interaction between NaAlH4 cluster and C60 with defect. The present results may provide valued insights of experimental work for exploring the catalytic potential of C60 with various defects.

  9. Compensation effect in the hydrogenation/dehydrogenation kinetics of metal hydrides.

    Science.gov (United States)

    Andreasen, Anders; Vegge, Tejs; Pedersen, Allan S

    2005-03-03

    The possible existence of a compensation effect, i.e. concurrent changes in activation energy and prefactor, is investigated for the hydrogenation and dehydrogenation kinetics of metal hydrides, by analyzing a series of reported kinetic studies on Mg and LaNi(5) based hydrides. For these systems, we find a clear linear relation between apparent prefactors and apparent activation energies, as obtained from an Arrhenius analysis, indicating the existence of a compensation effect. Large changes in apparent activation energies in the case of Mg based hydrides are rationalized in terms of a dependency of observed apparent activation energy on the degree of surface oxidation, i.e., a physical effect. On the other hand, we find the large concurrent changes in apparent prefactors to be a direct result of the Arrhenius analysis. Thus, we find the observed compensation effect to be an artifact of the data analysis rather than a physical phenomenon. In the case of LaNi(5) based hydrides, observed scatter in reported apparent activation energies is less pronounced supporting the general experience that LaNi(5) is less sensitive toward surface contamination.

  10. Study of the hydrogenation/dehydrogenation process in the Mg–Ni–C–Al system

    Energy Technology Data Exchange (ETDEWEB)

    Palumbo, O. [CNR-ISC, U.O.S. La Sapienza, Piazzale A. Moro 5, 00185 Roma (Italy); Research Center Hydro-Eco, Sapienza University of Rome, Via A. Scarpa 14, 00161 Roma (Italy); Trequattrini, F. [Physics Department, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Roma (Italy); Vitucci, F.M. [CNR-ISC, U.O.S. La Sapienza, Piazzale A. Moro 5, 00185 Roma (Italy); Bianchin, A. [MBN Nanomaterialia S.p.A., Via G. Bortolan 42, 31040 Vascon di Carbonera-TV (Italy); Paolone, A., E-mail: annalisa.paolone@roma1.infn.it [CNR-ISC, U.O.S. La Sapienza, Piazzale A. Moro 5, 00185 Roma (Italy); Research Center Hydro-Eco, Sapienza University of Rome, Via A. Scarpa 14, 00161 Roma (Italy)

    2015-10-05

    Highlights: • A Mg–Ni–C–Al mixture synthesized for application as pellets in a tank is studied. • It is the combination of a hydrogen storing composite with a binding phase. • The storage properties are studied by PCI curves, TGA–DSC and XRD. • The hydrogen absorbtion/desorption occurs in two steps. • The thermodynamics of the first more massive step is improved compared to MgH{sub 2}. - Abstract: In this work we present a detailed study of the hydrogenation and dehydrogenation processes of a nanostructured Mg–Ni–C–Al mixture. The sample has been characterized by means of X-ray diffraction, concomitant thermogravimetric and differential scanning calorimetry measurements and pressure-composition isothermal analyses. The hydrogenation takes place in two steps and is compatible with the formation of MgH{sub 2} and Mg{sub 2}NiH{sub 4}. The enthalpy and the activation energy measured for the main hydrogen desorption are lower than those ones reported for magnesium hydride.

  11. Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

    Directory of Open Access Journals (Sweden)

    Ryo eWatanabe

    2013-10-01

    Full Text Available For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1–xSrxFeyMn1–yO3–d(0 ≤ x≤ 1, 0.2 ≤ y≤ 0.8, perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst with that of an industrial potassium promoted iron (Fe–K catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d and the Fe–K catalysts in aH2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst while the Fe–K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3–d was superior to that of Fe–K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d perovskite oxide.

  12. Nb effect in the nickel oxide-catalyzed low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2012-01-01

    A method for the preparation of NiO and Nb-NiO nanocomposites is developed, based on the slow oxidation of a nickel-rich Nb-Ni gel obtained in citric acid. The resulting materials have higher surface areas than those obtained by the classical evaporation method from nickel nitrate and ammonium niobium oxalate. These consist in NiO nanocrystallites (7-13 nm) associated, at Nb contents >3 at.%., with an amorphous thin layer (1-2 nm) of a niobium-rich mixed oxide with a structure similar to that of NiNb 2O 6. Unlike bulk nickel oxides, the activity of these nanooxides for low-temperature ethane oxidative dehydrogenation (ODH) has been related to their redox properties. In addition to limiting the size of NiO crystallites, the presence of the Nb-rich phase also inhibits NiO reducibility. At Nb content >5 at.%, Nb-NiO composites are thus less active for ethane ODH but more selective, indicating that the Nb-rich phase probably covers part of the unselective, non-stoichiometric, active oxygen species of NiO. This geometric effect is supported by high-resolution transmission electron microscopy observations. The close interaction between NiO and the thin Nb-rich mixed oxide layer, combined with possible restructuration of the nanocomposite under ODH conditions, leads to significant catalyst deactivation at high Nb loadings. Hence, the most efficient ODH catalysts obtained by this method are those containing 3-4 at.% Nb, which combine high activity, selectivity, and stability. The impact of the preparation method on the structural and catalytic properties of Nb-NiO nanocomposites suggests that further improvement in NiO-catalyzed ethane ODH can be expected upon optimization of the catalyst. © 2011 Elsevier Inc. All rights reserved.

  13. Simulation of the styrene production process via catalytic dehydrogenation of ethylbenzene using CHEMCAD® process simulator

    Directory of Open Access Journals (Sweden)

    Amaury Pérez Sánchez

    2017-07-01

    Full Text Available Background: Process simulation has been extensively used in recent years to design, evaluate or optimize processes, systems and specific operations of the chemical industry and its related disciplines. Currently, CHEMCAD® constitute one of the most used process simulators because of the great number of chemical and petrochemical processes that can be simulated. Method: The simulation of the production process of styrene via catalytic dehydrogenation of ethyl-benzene is carried out by using the process simulator CHEMCAD® version 5.2.0, in order to determine the composition and mass flow-rate of each process involved in the production, as well as the main operating parameters of the equipment used. Two sensitivity studies were carried out: firstly, the influence of the temperature and pressure values applied at the LLV Separator on the amounts of ethyl-benzene and styrene to be obtained by the intermediate and top currents of this equipment; secondly, the influence of the operating pressure of the Distillation Column No. 1 (benzene-toluene column on the quantity of ethyl-benzene and styrene obtained at the bottom stream. The simulating software MATLAB® version 7.8.0 was used to process the results obtained. Results: Around 9234.436 kg/h of styrene is obtained in the last distillation column with 99.6% purity. Additionally, it was found that the water is the main impurity found on this stream, which represents 0.35% of the weight. Conclusions: The LLV Separator must operate at a low temperature (5 – 10 ºC and at a relatively high pressure (10 bar, whereas the Distillation Column No. 1 must work at a pressure near atmospheric (1.0 bar, or preferably under vacuum conditions in order to obtain the highest yields of styrene and ethyl-benzene.

  14. Oxidative dehydrogenation of isobutane over vanadia catalysts supported by titania nanoshapes

    Energy Technology Data Exchange (ETDEWEB)

    Kraemer, Shannon; Rondinone, Adam J.; Tsai, Yu-Tong; Schwartz, Viviane; Overbury, Steven H.; Idrobo, Juan-Carlos; Wu, Zili

    2016-04-01

    Support plays a complex role in catalysis by supported metal oxides and the exact support effect still remains elusive. One of the approaches to gain fundamental insights into the support effect is to utilize model support systems. In this paper, we employed for the first time titania nanoshapes as the model supports and investigated how the variation of surface structure of the support (titania, TiO2) impacts the catalysis of supported oxide (vanadia, VOx). TiO2 truncated rhombi, spheres and rods were synthesized via hydrothermal method and characterized with XRD and TEM. These TiO2 nanoshapes represent different mixtures of surface facets including [1 0 1], [0 1 0] and [0 0 1] and were used to support vanadia. The structure of supported VOx species was characterized in detail with in situ Raman spectroscopy as a function of loading on the three TiO2 nanoshapes. Oxidative dehydrogenation (ODH) of isobutane to isobutene was used as a model reaction to test how the support shape influences the activity, selectivity and activation energy of the surface VOx species. It was shown that the shape of TiO2 support does not pose evident effect on either the structure of surface VOx species or the catalytic performance of surface VOx species in isobutane ODH reaction. This insignificant support shape effect was ascribed to the small difference in the surface oxygen vacancy formation energy among the different TiO2 surfaces and the multi-faceting nature of the TiO2 nanoshapes.

  15. Modeling-based optimization of a fixed-bed industrial reactor for oxidative dehydrogenation of propane

    Institute of Scientific and Technical Information of China (English)

    Ali Darvishi; Razieh Davand; Farhad Khorasheh; Moslem Fattahi

    2016-01-01

    An industrial scale propylene production via oxidative dehydrogenation of propane (ODHP) in multi-tubular re-actors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of smal diameter tubes immersed in a shel through a proper coolant flows. Herein, a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence olefin over V2O5/γ-Al2O3 catalyst was presented. Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions, gas process and coolant temperatures, as well as other pa-rameters affecting the reactor performance such as pressure. Furthermore, the applied model showed that a double-bed multitubular reactor with intermediate air injection scheme was superior to a single-bed design due to the increasing of propylene selectivity while operating under lower oxygen partial pressures resulting in propane conversion of about 37.3%. The optimized length of the reactor needed to reach 100%conversion of the oxygen was theoretically determined. For the single-bed reactor the optimized length of 11.96 m including 0.5 m of inert section at the entrance region and for the double-bed reactor design the optimized lengths of 5.72 m for the first and 7.32 m for the second reactor were calculated. Ultimately, the use of a distributed oxygen feed with limited number of injection points indicated a significant improvement on the reactor performance in terms of propane conversion and propylene selectivity. Besides, this concept could overcome the reactor run-away temperature problem and enabled operations at the wider range of conditions to obtain enhanced propyl-ene production in an industrial scale reactor.

  16. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    Science.gov (United States)

    Kootenaei, A. H. Shahbazi; Towfighi, J.; Khodadadi, A.; Mortazavi, Y.

    2014-04-01

    Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

  17. Familial lipoprotein lipase deficiency

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000408.htm Familial lipoprotein lipase deficiency To use the sharing features on this page, please enable JavaScript. Familial lipoprotein lipase deficiency is a group of rare genetic ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... This Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video— ... treatment. For more information about living with and managing iron-deficiency anemia, go to the Health Topics ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type ... of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require ...

  20. Folate-deficiency anemia

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000551.htm Folate-deficiency anemia To use the sharing features on this page, please enable JavaScript. Folate-deficiency anemia is a decrease in red blood cells (anemia) ...

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... severity of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require treatment in a hospital, blood ... With and Managing Iron-Deficiency Anemia 05/18/2011 This video— ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type ... condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require treatment in ...

  3. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Deficiency Anemia What Is... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL ... and women are the two groups at highest risk for iron-deficiency anemia. Outlook Doctors usually can ...

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Deficiency Anemia Explore Iron-Deficiency Anemia What Is... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS ... Google+ SITE INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA NO FEAR ACT OIG CONTACT US National Institutes of Health ...

  5. Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2015-09-01

    The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

  6. Effect of Ce addition on the surface properties and n-dodecane dehydrogenation performance of Pt-Sn/Ce-Al2O3 catalyst

    Science.gov (United States)

    Li, Xianru; He, Songbo; Wei, Huangzhao; Luo, Sha; Gu, Bin; Sun, Chenglin

    2015-08-01

    Ce-modified alumina carriers with different Ce content were prepared by vacuum isovolume impregnation method aiming to improve the n-dodecane catalytic dehydrogenation performance of PtSn/Al2O3 catalyst. The support and catalyst were characterized by XRD, N2 adsorption-desorption, NH3-TPD, H2-TPR, CO-pulse adsorption and TG-DTG. Results showed that Ce addition decreased the surface acid amount significantly and inhibited the reduction of SnO x species. Besides, Ce containing catalyst showed higher n-dodecane dehydrogenation activity and stability and lower coke deposition amount and coke burning temperature. In our study, the optimal Ce addition amount for n-dodecane dehydrogenation was 2%.

  7. Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

    KAUST Repository

    Chen, Tao

    2016-05-31

    In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

  8. Synthesis and Characterization of Nearly Monodisperse Pt Nanoparticles for C1 to C3 Alcohol Oxidation and Dehydrogenation of Dimethylamine-borane (DMAB).

    Science.gov (United States)

    Erken, Esma; Yildiz, Yunus; Kilbaş, Benan; Sen, Fatih

    2016-06-01

    Highly efficient nearly monodisperse Pt NPs catalyze C1 to C3 alcohol oxidation with very high electrochemical activities and provides one of the highest catalytic activities (TOF = 21.50 h(-1)) in the dehydrogenation of DMAB at room temperature. The exceptional stability towards agglomeration, leaching and CO poisoning for the prepared catalyst allow these particles to be recycled and reused in the catalysis of both DMAB dehydrogenation and C1 to C3 alcohol oxidation. After four subsequent reaction and recovery cycles, catalyst retained ≥ 80% activity towards the complete dehydrogenation of DMAB. The prepared catalyst structures were determined by the X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) respectively.

  9. The influence of surface oxygen and hydroxyl groups on the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate on pure Pd(1 0 0): A DFT study

    Science.gov (United States)

    Huang, Yanping; Dong, Xiuqin; Yu, Yingzhe; Zhang, Minhua

    2016-12-01

    On the basis of a Langmuir-Hinshelwood-type mechanism, the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate (VAH) on pure Pd(1 0 0) with surface oxygen atoms (Os) and hydroxyl groups (OHs) was studied with density functional theory (DFT) method. Our calculation results show that both Os and OHs can consistently reduce the activation energies of dehydrogenation of ethylene, acetic acid and VAH to some degree with only one exception that OHs somehow increase the activation energy of VAH. Based on Langmuir-Hinshelwood mechanism, the three dehydrogenation reactions in presence of surface Os and OHs are almost consistently favored, compared with the corresponding processes on clean Pd(1 0 0) surfaces, and thus a Langmuir-Hinshelwood-type mechanism may not be excluded beforehand when investigating the microscopic performance of the oxygen-assisted vinyl acetate synthesis on Pd(1 0 0) catalysts.

  10. Alloying effect via comparative studies of ethanol dehydrogenation on Cu(1 1 1), Cu3Pd(1 1 1), and Cu3Pt(1 1 1)

    Science.gov (United States)

    Wu, Ruitao; Wang, Lichang

    2017-06-01

    Ethanol dehydrogenations on Cu(1 1 1), Cu3Pd(1 1 1), and Cu3Pt(1 1 1) were studied using density functional theory with a PBE functional. The α-C-H and β-C-H scissions are endothermic on all surfaces while the O-H scission is exothermic on Cu(1 1 1) and Cu3Pt(1 1 1) but endothermic on Cu3Pd(1 1 1). The ethanol dehydrogenation occurs on Cu(1 1 1) through both α-C-H and O-H scissions but on Cu3Pd(1 1 1) and Cu3Pt(1 1 1) through only α-C-H scission. Furthermore, alloying Pt or Pd with Cu shows an increase in reaction rate at 493 K by more than 3 orders of magnitude, thus illustrating the promise of alloying Pt or Pd in Cu catalysts for ethanol dehydrogenation.

  11. Metal free synthesis of functionalized 1-aryl isoquinolines via iodine mediated oxidative dehydrogenation and ring opening of lactam in isoindoloisoquinolinones

    Indian Academy of Sciences (India)

    KAMSALI MURALI MOHAN ACHARI; MUTHUPANDI KARTHICK; CHINNASAMY RAMARAJ RAMANATHAN

    2017-06-01

    A facile and convenient method for the synthesis of substituted 2-(isoquinolin-1-yl)benzoic acids from isoindoloisoquinolinones in the presence of molecular iodine under sealed tube condition at 100◦C has been developed. This methodology involves the oxidative dehydrogenation and ring opening of hydroxylactam/methoxy lactam to furnish the 2-(isoquinolin-1-yl)benzoic acids. Some of these acids are successfully cyclized to furnish the azabenzanthrone derivatives, the potential precursors for the synthesis of menisporphine alkaloids and daurioxoisoaporphines.

  12. Oxidative dehydrogenation of propane with K-MoO3/MgAl2O4 catalysts

    Indian Academy of Sciences (India)

    Serkan Naci Koc; Kubra Dayioglu; Hasan Ozdemir

    2016-01-01

    In this study, for the first time, MoO3/MgAl2O4 catalysts and their potassium-promoted forms were prepared and tested for oxidative dehydrogenation of propane. Catalysts were characterized with XRD, BET, NH3-TPD, TPR and XPS methods. Catalytic activity measurement was done with quartz microreactor between 450 and 550°C. It has been observed that the conversion of propane increased with temperature and total hydrocarbon selectivity increased with molybdenum oxide content. The acidity of catalysts decreased with potassium addition due to interaction with MoO3 sites. For this reason total hydrocarbon selectivity highly increased.

  13. Coupling dehydrogenation of isobutane in the presence of carbon dioxide over chromium oxide supported on active carbon

    Institute of Scientific and Technical Information of China (English)

    Jian Fei Ding; Zhang Feng Qin; Xue Kuan Li; Guo Fu Wang; Jian Guo Wang

    2008-01-01

    The dehydrogenation of isobutane (IB) to produce isobutene coupled with reverse water gas shift in the presence of carbon dioxide was investigated over the catalyst Cr2O3 supported on active carbon (Cr2O3/AC). The results illustrated that isobutane c onversion and isobutene yield can be enhanced through the reaction coupling in the presence of carbon dioxide. Moreover, carbon dioxide can partially eliminate carbonaceous deposition on the catalyst and keep the active phase (Cr2O3), which are then helpful to alleviate the catalyst deactivation.

  14. Iron-Deficiency Anemia

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, ... Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by ...

  15. Iron-Deficiency Anemia

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Deficiency Anemia? Español Iron-deficiency anemia is a common, easily treated condition that occurs if you don' ... from food. Overview Iron-deficiency anemia is a common type of anemia . The term "anemia" usually refers ...

  19. Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp2 C–H and sp3 C–H bonds

    Science.gov (United States)

    Bhunia, Subhajit

    2016-01-01

    Summary The synthesis of a variety of 2-oxindoles bearing an all-carbon quaternary center at the pseudo benzylic position has been achieved via a ‘transition-metal-free’ intramolecular dehydrogenative coupling (IDC). The construction of 2-oxindole moieties was carried out through formation of carbon–carbon bonds using KOt-Bu-catalyzed one pot C-alkylation of β-N-arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction. PMID:27559367

  20. Kinetic and thermodynamic parameters of hydrogen release during the heterogeneous catalytic dehydrogenation of cis- and trans-isomers of perhydro-m-terphenyl

    Science.gov (United States)

    Kalenchuk, A. N.; Bogorodskii, S. E.; Bogdan, V. I.

    2016-10-01

    Comparative studies on the temperature dependence of the dehydrogenation of cis- and trans-isomers of perhydro- m-terphenyl are performed in a flow catalytic reactor. Rate constants and equilibrium constants of all elementary acts of this reaction are calculated on basis of experimental data using the KINET 0.8 program for the mathematical modeling of the kinetics of complex reactions. The resulting data indicate that perhydro- m-terphenyl cis- and trans-isomers structural differences have no appreciable effect on dehydrogenation.

  1. Aerobic dehydrogenation of cyclohexanone to phenol catalyzed by Pd(TFA)2/2-dimethylaminopyridine: evidence for the role of Pd nanoparticles.

    Science.gov (United States)

    Pun, Doris; Diao, Tianning; Stahl, Shannon S

    2013-06-05

    We have carried out a mechanistic investigation of aerobic dehydrogenation of cyclohexanones and cyclohexenones to phenols with a Pd(TFA)2/2-dimethylaminopyridine catalyst system. Numerous experimental methods, including kinetic studies, filtration tests, Hg poisoning experiments, transmission electron microscopy, and dynamic light scattering, provide compelling evidence that the initial Pd(II) catalyst mediates the first dehydrogenation of cyclohexanone to cyclohexenone, after which it evolves into soluble Pd nanoparticles that retain catalytic activity. This nanoparticle formation and stabilization is facilitated by each of the components in the catalytic reaction, including the ligand, TsOH, DMSO, substrate, and cyclohexenone intermediate.

  2. One-Pot Cascade Synthesis of Quinazolin-4(3H)-ones via Nickel-Catalyzed Dehydrogenative Coupling of o-Aminobenzamides with Alcohols.

    Science.gov (United States)

    Parua, Seuli; Das, Siuli; Sikari, Rina; Sinha, Suman; Paul, Nanda D

    2017-07-21

    In this paper, we report a general, efficient, and environmentally benign method for the one-pot cascade synthesis of quinazolin-4(3H)-ones via acceptorless dehydrogenative coupling of o-aminobenzamide with alcohols catalyzed by a simple Ni(II) catalyst, [Ni(MeTAA)], featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)). A wide variety of substituted quinazolin-4(3H)-ones were synthesized in high yields starting from readily available benzyl alcohols and o-aminobenzamides. Several controlled reactions along with deuterium labeling studies were carried out to establish the acceptorless dehydrogenative nature of the reactions.

  3. Carnitine Deficiency and Pregnancy

    Directory of Open Access Journals (Sweden)

    Anouk de Bruyn

    2015-01-01

    Full Text Available We present two cases of carnitine deficiency in pregnancy. In our first case, systematic screening revealed L-carnitine deficiency in the first born of an asymptomatic mother. In the course of her second pregnancy, maternal carnitine levels showed a deficiency as well. In a second case, a mother known with carnitine deficiency under supplementation was followed throughout her pregnancy. Both pregnancies had an uneventful outcome. Because carnitine deficiency can have serious complications, supplementation with carnitine is advised. This supplementation should be continued throughout pregnancy according to plasma concentrations.

  4. A New Solid Sorbent System for Rapid Monitoring of Dehydrogenated Nicotine by Using Furfural-hydrochloric Acid

    Institute of Scientific and Technical Information of China (English)

    B. AMBADE; E. K. JANGHEL; M. K. RAI; G. L. MUNDHARA

    2006-01-01

    A new solid sorbent system is developed for the monitoring of dehydrogenated nicotine in the environment. The reagent system for the indicator tube consists of furfural-hydrochloric acid and phosphoric acid impregnated over a cellulose fibre (cotton) and a humectant calcium chloride. The reagent system has also been used for the preparation of reagent paper. After exposing the indicator tubes and test paper to dehydrogenated nicotine, for a constant time, the red-violet colour developed could be compared with those obtained from standards. Alternatively the coloured compound was extracted in water and the absorbance measured at 540 nm. The lower limit of detection is 0.03 μg/m3 of nicotine for the reagent papers and indicator tubes. The lower limit of determination by spectrophotometric procedure is 0.001 μg/m3 of air.The preparation of indicator tubes, test papers and their applications for the detection and determination of nicotine in environmental tobacco smoke (ETS), mainstream smoke (MS), side stream smoke (SS) and biological samples is described in this paper.

  5. Thermally Stable and Regenerable Platinum-Tin Clusters for Propane Dehydrogenation Prepared by Atom Trapping on Ceria

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Haifeng [Department of Chemical & Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque NM 87131 USA; Lin, Sen [Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350002 China; Goetze, Joris [Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99 3584 CG Utrecht The Netherlands; Pletcher, Paul [Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99 3584 CG Utrecht The Netherlands; Guo, Hua [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque NM 87131 USA; Kovarik, Libor [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA; Artyushkova, Kateryna [Department of Chemical & Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque NM 87131 USA; Weckhuysen, Bert M. [Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99 3584 CG Utrecht The Netherlands; Datye, Abhaya K. [Department of Chemical & Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque NM 87131 USA

    2017-06-28

    CeO2 supports are unique in their ability to trap ionic Pt, providing exceptional stability for isolated single atoms of Pt. Here, we explore the reactivity and stability of single atom Pt species for the industrially important reaction of light alkane dehydrogenation. The single atom Pt/CeO2 catalysts are stable during propane dehydrogenation, but we observe no selectivity towards propene. DFT calculations show strong adsorption of the olefin produced, leading to further unwanted reactions. In contrast, when Sn is added to ceria, the single atom Pt catalyst undergoes an activation phase where it transforms into Pt-Sn clusters under reaction conditions. Formation of small Pt-Sn clusters allows the catalyst to achieve high selectivity towards propene, due to facile desorption of the product. The CeO2-supported Pt-Sn clusters are very stable, even during extended reaction at 680 °C. By adding water vapor to the feed, coke formation can almost completely be suppressed. Furthermore, the Pt-Sn clusters can be readily transformed back to the atomically dispersed species on ceria via oxidation, making Pt-Sn/CeO2 a fully regenerable catalyst.

  6. VO x /SiO 2 Catalyst Prepared by Grafting VOCl 3 on Silica for Oxidative Dehydrogenation of Propane

    KAUST Repository

    Zhu, Haibo

    2015-09-07

    The VOx/SiO2 catalysts for oxidative dehydrogenation of propane were synthesized by a simple grafting method. The VOCl3 was first grafted at the surface of SiO2, which was dehydrated at different temperature (from 200 to 1000°C). The formed grafted complexes were then calcined in air, leading to the formation of VOx/SiO2 catalysts. The synthesized catalysts were characterized by nitrogen adsorption, SEM, Raman spectroscopy, temperature-programmed reduction, and extended X-ray absorption fine structure analysis. The SiO2 pretreatment temperature has an evident effect on the loading and dispersion of VOx on SiO2, which finally affects their catalytic performance. High SiO2 treatment temperature is beneficial to dispersing the vanadium oxide species at the SiO2 surface. These materials are efficient catalysts for the catalytic oxidative dehydrogenation of propane to propylene. The best selectivity to propylene is achieved on the VOx/SiO2-(1000) catalyst. The high selectivity and activity are well maintained for three days catalytic reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Cu, Fe, or Ni doped molybdenum oxide supported on Al2O3 for the oxidative dehydrogenation of ethylbenzene

    Institute of Scientific and Technical Information of China (English)

    Tiago Pinheiro Braga; Antônio Narcísio Pinheiro; Edson R. Leite; Regina Cláudia R. dos Santos; Antoninho Valentini

    2015-01-01

    Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an unconventional route that combined the polymeric precursor method (Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, temperature-programmed reduction of H2 (H2-TPR), and thermogravimetric (TG) analysis. XRD results showed that the added metals were well dis-persed on the alumina support. The addition of the metal oxide (Ni, Cu, or Fe) of 2 wt% by wet im-pregnation did not affect the texture of the support. TPR results indicated a synergistic effect be-tween the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conver-sion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity.

  8. Microcalorimetric Adsorption of Alumina Oxide Catalysts for Combination of Ethylbenzene dehydrogenation and carbon Dioxide Shift-reaction

    Institute of Scientific and Technical Information of China (English)

    GE Xin; SHEN Jian-yi

    2004-01-01

    Styrene (STY) is now produced industrially in fairly large quantities by the dehydrogenation of ethylbenzene (EB) using promoted iron oxide catalyst with superheated steam.In this case, small amount of carbon dioxide formed as a by-product was known to inhibit the catalytic activity of commercial catalyst. Recently, there have been some reports which carbon dioxide showed positive effects to promote catalytic activities on the reaction over several catalysts.In this study, we attempted to combine the dehydrogenation of EB to STY with the carbon dioxide shift-reaction. The combine reaction (EB + CO2 → STY + H2O + CO) can be considered as one of the ways of using CO2 resources and can yield simultaneously STY and Carbon oxide.Alumina oxide catalysts such as Al2O3, Na2O/Al2O3 and K2O/Al2O3 were prepared by the usual impregnation method with an aqueous solution of NaNO3 and KNO3, and then calcined at 650℃ for 5 h in a stream of air. The reaction condition is 600℃, flow of CO2 38ml/mon and space velocity (EB) 1.28h-1.

  9. Oxidative dehydrogenation of propane on the VO x /CeZrO/Al2O3 supported catalyst

    Science.gov (United States)

    Turakulova, A. O.; Kharlanov, A. N.; Levanov, A. V.; Lunin, V. V.

    2017-05-01

    The oxidative dehydrogenation of propane on a supported vanadium catalyst was studied (the support was a complex oxide system consisting of a ceria-zirconia solid solution deposited on γ-Al2O3 (CeZrO/γ-Al2O3)). A comparative analysis of the properties of the support and the catalyst prepared on its basis was performed. The support and catalyst were characterized by the BET method, scanning electron microscopy, X-ray diffraction analysis, and Raman spectroscopy. The catalytic properties of the catalyst and support were studied in propane oxidation at 450 and 500°C with pulse feeding of the reagent. The effect of propane on the support was found to improve the oxidative properties of the latter. This behavior of the support is related to the preparation procedure, which leads to the formation on its surface of the crystalline phase of the ceria-zirconia solid solution and amorphous ZrO2 and Al2O3 phases and/or their solid solution. Similar processes occur with the catalyst support during the oxidative dehydrogenation, giving rise to additional active centers (CeVO4).

  10. Ru-N-C Hybrid Nanocomposite for Ammonia Dehydrogenation: Influence of N-doping on Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Bich Hien

    2015-06-01

    Full Text Available For application to ammonia dehydrogenation, novel Ru-based heterogeneous catalysts, Ru-N-C and Ru-C, were synthesized via simple pyrolysis of a mixture of RuCl3·6H2O and carbon black with or without dicyandiamide as a nitrogen-containing precursor at 550 °C. Characterization of the prepared Ru-N-C and Ru-C catalysts via scanning transmission electron microscopy, in conjunction with energy dispersive X-ray spectroscopy, indicated the formation of hollow nanocomposites in which the average sizes of the Ru nanoparticles were 1.3 nm and 5.1 nm, respectively. Compared to Ru-C, the Ru-N-C nanocomposites not only proved to be highly active for ammonia dehydrogenation, giving rise to a NH3 conversion of >99% at 550 °C, but also exhibited high durability. X-ray photoelectron spectroscopy revealed that the Ru active sites in Ru-N-C were electronically perturbed by the incorporated nitrogen atoms, which increased the Ru electron density and ultimately enhanced the catalyst activity.

  11. Mechanistic and kinetic analysis of the oxidative dehydrogenation of ethane via novel supported alkali chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.; Veen, A.C. van; Lercher, J.A. [Technische Universitaet Muenchen (Germany). Catalysis Research Center

    2013-11-01

    The oxidative dehydrogenation of ethane over advanced catalysts is promising to selectively produce ethylene, an essential building block for the chemical industry. In this way, ethane from shale gas can be efficiently valorized. Supported alkali chloride catalysts are investigated in this work. Essential feature of those materials is the presence of a solid core (magnesium oxide in part doped with Dy{sub 2}O{sub 3}) covered under reaction conditions with a molten alkali chloride shell. It is shown that especially the lowered melting point of eutectic mixtures of LiCl with other alkali/alkaline earth metals is the key to taylor highly efficient materials. Elucidating the ODH reaction mechanism is essential to understand the reactivity of this novel catalyst class and provides the basis for improving performances. Information about elementary steps and the rate determining step were extracted from kinetic measurements, both in steady state and in transient configuration. Furthermore, isotopic labelling studies were performed, i.e. SSITKA studies and temperature programmed isotopic exchange experiments. Step experiments showed a significant oxygen uptake by the catalysts. Retained oxygen reacted quantitatively with ethane at nearly 100% selectivity to ethylene and conversion rates were comparable with rates observed during steady state operation. Thus, chemically bound oxygen in the melt is the active and selective intermediate in the ODH. Therefore, it is required to consider an intermediate and the activation is concluded to relate to the oxygen dissociation. The total concentration of stored oxygen can be correlated to the steady-state activity, while the viscosity of the melts mainly influences the selectivity towards ethene. Properties of the solid core impact on the catalyst efficiency suggesting that the oxygen species forms at the interface between support and overlayer. The quantity of retained oxygen additionally depends on the properties of the chloride

  12. Mo-V-Te-Nb oxides as catalysts for ethene production by oxidative dehydrogenation of ethane

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, D. [Technische Universitaet Muenchen, Garching (Germany). Dept. of Chemistry and Catalysis Research Center; Meiswinkel, A.; Thaller, C.; Bock, M.; Alvarado, L. [Linde AG, Pullach (Germany)

    2013-11-01

    The availability of ethane in shale gas, as well as the interest in valorising previously underutilized carbon feedstocks, makes the oxidative dehydrogenation (ODH) of ethane an attractive alternative to the industrially established processes for production of ethylene. Mo-V-Te-Nb mixed oxide has been chosen as catalyst for the ODH reaction in view of its outstanding ability to activate alkane molecules. Catalytic test results showed that this type of catalyst can selectively oxidize ethane to ethene at moderate temperatures (350-400 C) with minor production of CO{sub x}. The catalytic performance of Mo-V-Te-Nb mixed-oxide is mainly attributable to the crystalline phase 'M1'. Rietveld analysis of the X-Ray diffractograms allowed us to quantify the amount of MoVTeNb oxide that has crystallized as M1. In this way, it was possible to find a linear correlation of the reaction rate with the abundance of M1 in the solid. Therefore, it is clear that for improving the efficiency of MoVTeNb oxide in ODH, the amount of M1 in the catalyst should be maximized. With this purpose, several MoVTeNb oxides were subject to different thermal treatments prior to the catalytic test. Structural changes in the catalyst were monitored by in-situ XRD technique. Under oxidative atmosphere, it was observed a recrystallization of M2 and possibly, amorphous oxide, into M1 phase, leading to correspondingly more active and selective catalysts (selectivities above 95 % for ethane conversions up to 40 % under industrially relevant conditions). The active site of M1 involves V species, likely with redox properties enhanced by the proximity of Mo and Te species, while the function of the crystalline structure itself is to provide the spatial configuration that allows interaction between these species. However, ethene formation rate was observed to be independent of the V content of the samples. The vanadium species exposed at the surface were studied by LEIS and by IR spectroscopy of CO

  13. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  14. Acquired color vision deficiency.

    Science.gov (United States)

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  15. Influence of the Pressure on the Product Distribution in the Oxidative Dehydrogenation of Propane over a Ga2O3/MoO3 Catalyst

    NARCIS (Netherlands)

    Kotanjac, Zeljko; Niederer, John; Versteeg, Geert

    2007-01-01

    The yields and selectivities in both the catalyzed and non-catalyzed oxidative dehydrogenation of propane were found to increase with increasing pressure. The results showed that the maximum yields of valuable ODH products could be obtained by adjusting only reactants' partial pressure, while

  16. Direct Dehydrogenation of n-Butane Over Pt/Sn/Zn-K/Al2O3 Catalyst: Effect of Hydrogen in the Feed.

    Science.gov (United States)

    Lee, Jong Kwon; Seo, Hyun; Kim, Jeong Kwon; Seo, Hanuk; Cho, Hye-Ran; Lee, Jinsuk; Chang, Hosik; Song, In Kyu

    2016-05-01

    Al2O3 was prepared by a sol-gel method for use as a support. Pt/Sn/Zn-K/Al2O3 catalyst was then prepared by a sequential impregnation method, and it was applied to the direct dehydrogenation of n-butane to n-butenes and 1,3-butadiene. Physicochemical properties of Pt/Sn/Zn-K/Al2O3 catalyst were examined by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, inductively coupled plasma atomic emission spectroscopy (ICP-AES), temperature-programmed reduction (TPR), CO chemisorption, and temperature-programmed oxidation (TPO) measurements. In order to improve the catalyst stability, the effect of hydrogen in the feed on the catalytic performance in the direct dehydrogenation of n-butane was studied. The catalyst stability and reusability in the direct dehydrogenation of n-butane was also investigated. Experimental results revealed that the addition of hydrogen in the feed decreased conversion of n-butane and yield for total dehydrogenation products but improved the stability of the catalyst. The catalytic activity and stability of regenerated Pt/Sn/Zn-K/Al2O3 catalyst in the presence of hydrogen slightly decreased compared to those of fresh Pt/Sn/Zn-K/Al2O3 catalyst due to the slight sintering of platinum particles.

  17. Carbon covered alumina prepared by the pyrolysis of sucrose: A promising support material for the supported Pt-Sn-bimetallic dehydrogenation catalysis

    NARCIS (Netherlands)

    Luo, S.; He, S.; Li, X.R.; Seshan, K.

    2014-01-01

    Sucrose was pyrolyzed on gamma alumina surface to prepare carbon covered alumina (CCA) material. Alumina and CCA supported Pt–Sn catalysts were prepared by the complex impregnation method under vacuum. Dehydrogenation of n-octadecane was performed to study the effect of carbon addition, Pt loading a

  18. Real-Time Quantitative Operando Raman Spectroscopy of a CrOx/Al2O3 Propane Dehydrogenation Catalyst in a Pilot-Scale Reactor

    NARCIS (Netherlands)

    Sattler, Jesper J. H. B.|info:eu-repo/dai/nl/328235601; Mens, Ad M.; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2014-01-01

    Combined operando UV/vis-Raman spectroscopy has been used to study the deactivation of CrOx/Al2O3 catalyst extrudates in a pilot scale propane dehydrogenation reactor. For this purpose, UV/vis and Raman optical fiber probes have been designed, constructed and tested. The light absorption measured by

  19. Dehydrogenation kinetics for pure and nickel-doped magnesium hydride investigated by in-situ, time-resolved powder diffraction (poster)

    DEFF Research Database (Denmark)

    Jensen, T.R.; Andreasen, A.; Vegge, T.;

    2004-01-01

    under isothermal conditions with a time resolution of 45 s. Three phases were identified, Mg,MgH2 and MgO, and the phase fractions were extracted for each phase. Dehydrogenation curves wereconstructed and analyzed by the Johnson-Mehl-Avrami formalism in order to derive rateconstants at different...

  20. Solid-Solid heterogeneous catalysis: the role of potassium in promoting the dehydrogenation of the Mg(NH(2))(2)/2 LiH composite.

    Science.gov (United States)

    Wang, Jianhui; Chen, Ping; Pan, Hongge; Xiong, Zhitao; Gao, Mingxia; Wu, Guotao; Liang, Chu; Li, Cao; Li, Bo; Wang, Jieru

    2013-11-01

    Considerable efforts have been devoted to the catalytic modification of hydrogen storage materials. The K-modified Mg(NH2 )2 /2 LiH composite is a typical model for such studies. In this work, we analyze the origin of the kinetic barrier in the first step of the dehydrogenation and investigate how K catalyzes this heterogeneous solid-state reaction. Our results indicate that the interface reaction of Mg(NH2 )2 and LiH is the main source of the kinetic barrier at the early stage of the dehydrogenation for the intensively ball-milled Mg(NH2 )2 /2 LiH sample. K can effectively activate Mg(NH2 )2 as well as promote LiH to participate in the dehydrogenation. Three K species of KH, K2 Mg(NH2 )4 , and Li3 K(NH2 )4 likely transform circularly in the dehydrogenation (KH↔K2 Mg(NH2 )4 ↔KLi3 (NH2 )4 ), which creates a more energy-favorable pathway and thus leads to the overall kinetic enhancement. This catalytic role of K in the amide/hydride system is different from the conventional catalysis of transition metals in the alanate system. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. On the stability of conventional and nano-structured carbon-based catalysts in the oxidative dehydrogenation of ethylbenzene under industrially relevant conditions

    NARCIS (Netherlands)

    Zarubina, Valeriya; Talebi, Hesamoddin; Nederlof, Christian; Kapteijn, Freek; Makkee, Michiel; Melian-Cabrera, Ignacio

    2014-01-01

    Relevant carbon-based materials, home-made carbon-silica hybrids, commercial activated carbon, and nanostructured multi-walled carbon nanotubes (MWCNT) were tested in the oxidative dehydrogenation of ethylbenzene (EB). Special attention was given to the reaction conditions, using a relatively concen

  2. Carbon covered alumina prepared by the pyrolysis of sucrose: A promising support material for the supported Pt-Sn-bimetallic dehydrogenation catalysis

    NARCIS (Netherlands)

    Luo, S.; He, Songbo; Li, X.R.; Seshan, Kulathuiyer

    2014-01-01

    Sucrose was pyrolyzed on gamma alumina surface to prepare carbon covered alumina (CCA) material. Alumina and CCA supported Pt–Sn catalysts were prepared by the complex impregnation method under vacuum. Dehydrogenation of n-octadecane was performed to study the effect of carbon addition, Pt loading

  3. DDQ-promoted dehydrogenation from natural rigid polycyclic acids or flexible alkyl acids to generate lactones by a radical ion mechanism.

    Science.gov (United States)

    Ding, Ye; Huang, Zhangjian; Yin, Jian; Lai, Yisheng; Zhang, Shibo; Zhang, Zhiguo; Fang, Lei; Peng, Sixun; Zhang, Yihua

    2011-09-07

    A novel and facile DDQ-mediated dehydrogenation from natural rigid polycyclic acids or flexible alkyl acids to generate lactones is described. The formation of lactones proceeds by a radical ion mechanism, which has been established by DPPH˙-mediated chemical identification, ESR spectroscopy and an enol intermediate trapping.

  4. Synthesis of bis- and tris(indolylmethanes catalyzed by an inorganic nano-sized catalyst followed by dehydrogenation to hyperconjugated products

    Directory of Open Access Journals (Sweden)

    Khorshidi Alireza

    2016-01-01

    Full Text Available A set of bis- and tris(indolylmethanes were prepared and dehydrogenated to their hyperconjugated products in a one-pot fashion. Nano-sized-SO3H functionalized mesoporous KIT-6 coated on magnetite nanoparticles (Fe3O4@SiO2@KIT-6-OSO3H was used as an efficient catalyst in the first step of synthesis, and dehydrogenation was performed by using (NH42S2O8 after removal of the catalyst. The catalyst was fully characterized by Fourier transform infrared spectroscopy (FT-IR, transmission electron microscopy (TEM and X-ray powder diffraction (XRD, as well as nitrogen adsorption-desorption isotherms. The bis- and tris(indolylmethanes were studied by UV-Vis spectroscopy before and after dehydrogenation, and effect of the ambient parameters on their spectra was investigated. It was found that bis- and tris(indolylmethanes have no considerable absorption in the visible range and what makes them colorful is partial dehydrogenation due to exposure to air. Our catalyst as a new combination of known materials, showed superiority in terms of yield, time, and mild reaction conditions in comparison with previous reports.

  5. A kinetic rate expression for the time-dependent coke formation rate during propane dehydrogenation over a platinum alumina monolithic catalyst.

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2001-01-01

    Coke formation rates under propane dehydrogenation reaction conditions on a used monolithic Pt/y-Al2O3 catalyst have been experimentally determined in a thermogravimetric analyser (TGA) as a function of time on stream covering wide temperature and concentration ranges. For relatively short times on

  6. Reversible cyclometalation at Rh-I as a motif for metal-ligand bifunctional bond activation and base-free formic acid dehydrogenation

    NARCIS (Netherlands)

    Jongbloed, L.S.; de Bruin, B.; Reek, J.N.H.; Lutz, M.; van der Vlugt, J.I.

    2016-01-01

    Reversible cyclometalation is demonstrated as a strategy for the activation of small protic molecules, with a proof-of-principle catalytic application in the dehydrogenation of formic acid in the absence of an exogenous base. The well-defined RhI complex Rh(CO)(L) 1, bearing the reactive cyclometala

  7. Reversible cyclometalation at RhI as a motif for metal–ligand bifunctional bond activation and base-free formic acid dehydrogenation

    NARCIS (Netherlands)

    Jongbloed, L. S.; De Bruin, B.; Reek, J. N. H.; Lutz, M.|info:eu-repo/dai/nl/304828971; Van Der Vlugt, J. I.

    2016-01-01

    Reversible cyclometalation is demonstrated as a strategy for the activation of small protic molecules, with a proof-of-principle catalytic application in the dehydrogenation of formic acid in the absence of an exogenous base. The well-defined RhI complex Rh(CO)(L) 1, bearing the reactive cyclometala

  8. Dehydrogenation kinetics of pure and nickel-doped magnesium hydride investigated by in situ time-resolved powder X-ray diffraction

    DEFF Research Database (Denmark)

    Jensen, T.R.; Andreasen, A.; Vegge, Tejs

    2006-01-01

    by the Johnson-Mehi-Avrami formalism in order to derive rate constants at different temperatures. The apparent activation energies for dehydrogenation of pure and Ni-doped magnesium hydride were E-A approximate to 300 and 250 kJ/mol, respectively. Differential scanning calorimetry gave, E-A = 270 k...

  9. Carbon covered alumina prepared by the pyrolysis of sucrose: A promising support material for the supported Pt-Sn-bimetallic dehydrogenation catalysis

    NARCIS (Netherlands)

    Luo, S.; He, Songbo; Li, X.R.; Seshan, Kulathuiyer

    2014-01-01

    Sucrose was pyrolyzed on gamma alumina surface to prepare carbon covered alumina (CCA) material. Alumina and CCA supported Pt–Sn catalysts were prepared by the complex impregnation method under vacuum. Dehydrogenation of n-octadecane was performed to study the effect of carbon addition, Pt loading a

  10. Dimethylammonium hexanoate stabilized rhodium(0) nanoclusters identified as true heterogeneous catalysts with the highest observed activity in the dehydrogenation of dimethylamine-borane.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ozkar, Saim

    2009-09-21

    Herein we report the discovery of a superior dimethylamine-borane dehydrogenation catalyst, more active than the prior best heterogeneous catalyst (Jaska, C. A.; Manners, I. J. Am. Chem. Soc. 2004, 126, 9776) reported to date for the dehydrogenation of dimethylamine-borane. The new catalyst system consists of rhodium(0) nanoclusters stabilized by C(5)H(11)COO(-) anions and Me(2)H(2)N(+) cations and can reproducibly be formed from the reduction of rhodium(II) hexanoate during dehydrogenation of dimethylamine-borane at room temperature. Rhodium(0) nanoclusters in an average particle size of 1.9 +/- 0.6 nm Rh(0)(approximately 190) nanoclusters) provide 1040 turnovers over 26 h with a record initial turnover frequency (TOF) of 60 h(-1) (the average TOF value is 40 h(-1)) in the dehydrogenation of dimethylamine-borane, yielding 100% of the cyclic product (Me(2)NBH(2))(2) at room temperature. The work reported here also includes the full experimental details of the following major components: (i) Characterization of dimethylammonium hexanoate stabilized rhodium(0) nanoclusters by using TEM, STEM, EDX, XRD, UV-vis, XPS, FTIR, (1)H, (13)C, and (11)B NMR spectroscopy, and elemental analysis. (ii) Collection of a wealth of previously unavailable kinetic data to determine the rate law and activation parameters for catalytic dehydrogenation of dimethylamine-borane. (iii) Monitoring of the formation kinetics of the rhodium(0) nanoclusters by a fast dimethylamine-borane dehydrogenation catalytic reporter reaction (Watzky, M. A.; Finke, R. G. J. Am. Chem. Soc. 1997, 119, 10382) at various [Me(2)NH.BH(3)]/[Rh] ratios and temperatures. Significantly, sigmoidal kinetics of catalyst formation was found to be well fit to the two-step, slow nucleation and then autocatalytic surface growth mechanism, A --> B (rate constant k(1)) and A + B --> 2B (rate constant k(2)), in which A is [Rh(C(5)H(11)CO(2))(2)](2) and B is the growing, catalytically active rhodium(0) nanoclusters. (iv) Mercury

  11. Metal-Borohydride-Modified Zr(BH4 )4 ⋅8 NH3 : Low-Temperature Dehydrogenation Yielding Highly Pure Hydrogen.

    Science.gov (United States)

    Huang, Jianmei; Ouyang, Liuzhang; Gu, Qinfen; Yu, Xuebin; Zhu, Min

    2015-10-12

    Due to its high hydrogen density (14.8 wt %) and low dehydrogenation peak temperature (130 °C), Zr(BH4 )4 ⋅8 NH3 is considered to be one of the most promising hydrogen-storage materials. To further decrease its dehydrogenation temperature and suppress its ammonia release, a strategy of introducing LiBH4 and Mg(BH4 )2 was applied to this system. Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 and Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 composites showed main dehydrogenation peaks centered at 81 and 106 °C as well as high hydrogen purities of 99.3 and 99.8 mol % H2 , respectively. Isothermal measurements showed that 6.6 wt % (within 60 min) and 5.5 wt % (within 360 min) of hydrogen were released at 100 °C from Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 and Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 , respectively. The lower dehydrogenation temperatures and improved hydrogen purities could be attributed to the formation of the diammoniate of diborane for Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 , and the partial transfer of NH3 groups from Zr(BH4 )4 ⋅8 NH3 to Mg(BH4 )2 for Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 , which result in balanced numbers of BH4 and NH3 groups and a more active H(δ+) ⋅⋅⋅(-δ) H interaction. These advanced dehydrogenation properties make these two composites promising candidates as hydrogen-storage materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Effective participation of Li4(NH2)3BH4 in the dehydrogenation pathway of the Mg(NH2)2-2LiH composite.

    Science.gov (United States)

    Amica, G; Cova, F; Arneodo Larochette, P; Gennari, F C

    2016-07-21

    Lithium fast-ion conductors have shown positive effects on the hydrogen storage properties of the Li-Mg-N-H system. In the present work, Li4(NH2)3BH4 doped Mg(NH2)2-2LiH was formed by milling the 2LiNH2-MgH2-0.2LiBH4 composite and posterior annealing under hydrogen pressure to reduce the kinetic barrier of the Li-Mg-N-H system. The effect of repetitive dehydrogenation/rehydrogenation cycles on the kinetic and thermodynamic performance was evaluated. The dehydrogenation rate in the doped composite was twice that in the un-doped sample at 200 °C, while hydrogenation was 20 times faster. The activation energy decreases by 9% due to the presence of Li4(NH2)3BH4 compared to the un-doped composite, evidencing its catalytic role. The presence of Li4(NH2)3BH4 in the composite stabilized the hydrogen storage capacity after successive sorption cycles. Thermodynamic studies revealed a variation in the pressure composition isotherm curves between the first dehydrogenation cycle and the subsequent. The Li4(NH2)3BH4 doped composite showed a sloped plateau region at higher equilibrium pressure in regard to the flat plateau of the un-doped composite. Detailed structural investigations revealed the effective influence of Li4(NH2)3BH4 in different reactions: the irreversible dehydrogenation in the presence of MgH2 and the reversible hydrogen release when it reacts with Li2Mg2(NH)3. The role of Li4(NH2)3BH4 in improving the dehydrogenation kinetics is associated with the weakening of the N-H bond and the mobile small ion mass transfer enhancement.

  13. Copper-based nanocatalysts for 2-butanol dehydrogenation: Screening and optimization of preparation parameters by response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Geravand, Elham; Shariatinia, Geravand; Yaripour, Fereydoon [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sahebdelfar, Saeed [National Iranian Petrochemical Company, P. O. Box 1493, Tehran (Iran, Islamic Republic of)

    2015-12-15

    Two types of copper-based dehydrogenation nanocatalysts (Cu/ZnO/Al{sub 2}O{sub 3} and Cu/SiO{sub 2}) were prepared from various precursors by impregnation (IM), sol-gel (SG) and co precipitation (COPRE) methods. The structures of samples were characterized by N{sub 2} adsorption-desorption, XRD, XRF, TPR, N{sub 2}O-Titration, FT-IR, FE-SEM and TEM techniques. The catalytic performance tests in vapor-phase dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were carried out in a fixed-bed reactor at a temperature of 260 .deg. C under atmospheric pressure and LHSV of 4mL/(h·g cat). The experimental results indicated that (i) the copper oxide over the COPRE nanocatalyst was reduced at a lower temperature (222 .deg. C) in comparison with the CuO reduced on the SG and IM samples (243 and 327 .deg. C, respectively). Also, the percentage of reduction of CuO species on COPRE catalyst was the highest (98.8%) in comparison with the two other samples, (ii) the COPRE nanocatalyst exhibited the highest activity for the dehydrogenation of 2-butanol to MEK, and (iii) co-precipitation method was selected as an optimum method for preparation of nanocatalyst. The central composite experimental design method was applied for investigation of the effects of four critical preparation factors on the MEK selectivity of Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst. The results showed that Cu/Zn molar ratio and precipitation pH are the most effective factors on the response and the optimum conditions for synthesis of Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst with maximum selectivity of MEK were T(pre)=67.5 .deg. C, T(aging)=68.8 .deg. C, pH(pre)=7.27 and Cu/Zn molar ratio=1.38. The performance of the prepared nanocatalyst at the optimum conditions was comparable to the commercially available nanocatalyst.

  14. Crystal chemistry of volcanic allanites indicative of naturally induced oxidation-dehydrogenation

    Science.gov (United States)

    Hoshino, Mihoko; Kimata, Mitsuyoshi; Chesner, Craig A.; Nishida, Norimasa; Shimizu, Masahiro; Akasaka, Takeshi

    2010-05-01

    welding of the Youngest Toba Tuff caused the following post-crystallization changes to occur in YTT allanite: oxidation of Fe2+ to Fe3+, release of H2, and the concomitant replacement of OH- by O2-. These oxidation and dehydrogenation processes advanced during the welding to thereby produce oxyallanite. Oxyallanite had been reported only in laboratory studies where it was produced by heating natural allanite. Our report on natural oxyallanite suggests that it may be present in other welded silicic volcanic rocks as well.

  15. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Blood Tests Blood Transfusion Restless Legs Syndrome Send a link to NHLBI to someone by E-MAIL | ... Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily treated condition that occurs if you ...

  17. Iron deficiency anemia

    Science.gov (United States)

    Anemia - iron deficiency ... iron from old red blood cells. Iron deficiency anemia develops when your body's iron stores run low. ... You may have no symptoms if the anemia is mild. Most of the time, ... slowly. Symptoms may include: Feeling weak or tired more often ...

  18. Muscle phosphorylase kinase deficiency

    DEFF Research Database (Denmark)

    Preisler, N; Orngreen, M C; Echaniz-Laguna, A;

    2012-01-01

    To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD).......To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD)....

  19. Growth Hormone Deficiency

    Directory of Open Access Journals (Sweden)

    Ömer Tarım

    2010-05-01

    Full Text Available Growth hormone deficiency is the most promising entity in terms of response to therapy among the treatable causes of growth retardation. It may be due to genetic or acquired causes. It may be isolated or a part of multiple hormone deficiencies. Diagnostic criteria and therefore treatment indications are still disputed. (Journal of Current Pediatrics 2010; 8: 36-8

  20. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... periods. By following her treatment plan and making smart lifestyle choices, Susan continues to feel better and see the benefits of treatment. For more information about living with and managing iron-deficiency anemia, go to the Health Topics Iron-Deficiency Anemia article. Updated: March 26, ...

  2. Iron induced nickel deficiency

    Science.gov (United States)

    It is increasingly apparent that economic loss due to nickel (Ni) deficiency likely occurs in horticultural and agronomic crops. While most soils contain sufficient Ni to meet crop requirements, situations of Ni deficiency can arise due to antagonistic interactions with other metals. This study asse...

  3. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  4. Deficiently Extremal Gorenstein Algebras

    Indian Academy of Sciences (India)

    Pavinder Singh

    2011-08-01

    The aim of this article is to study the homological properties of deficiently extremal Gorenstein algebras. We prove that if / is an odd deficiently extremal Gorenstein algebra with pure minimal free resolution, then the codimension of / must be odd. As an application, the structure of pure minimal free resolution of a nearly extremal Gorenstein algebra is obtained.

  5. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Blood Tests Blood Transfusion Restless Legs Syndrome Send a link to NHLBI to someone by E-MAIL | ... Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily treated condition that occurs if you ...

  6. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  7. Preparation and characterization of Ni-Zr-O nanoparticles and its catalytic behavior for ethane oxidative dehydrogenation

    Science.gov (United States)

    Wu, Ying; Gao, Jing; He, Yiming; Wu, Tinghua

    2012-03-01

    Ni-Zr-O nanoparticles with various Zr contents were prepared by a modified sol-gel method and characterized by X-ray diffraction (XRD), scanning/high-resolution transmission electron microscope (SEM/HRTEM), BET surface area analysis, H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and O2 temperature-programmed desorption (O2-TPD). The oxidative dehydrogenation of ethane (ODHE) to ethylene was applied to evaluate catalytic performance of the samples. The results show that the doping of Zr affected the cell parameter and the chemical environment of the catalysts, indicating the existence of strong interaction between Ni and Zr. The interaction plays an important role in the lessened reducibility and the distribution of adsorbed oxygen species, consequently influence their catalytic performance. The best yield to ethylene was obtained over the 10% Ni-Zr-O catalyst with 60% ethane conversion and 66% ethylene selectivity.

  8. Mathematical Modeling and Simulation of the Dehydrogenation of Ethyl Benzene to Form Styrene Using Steady-State Fixed Bed Reactor

    Directory of Open Access Journals (Sweden)

    Zaidon M. Shakoor

    2013-05-01

    Full Text Available In this research, two models are developed to simulate the steady state fixed bed reactor used for styrene production by ethylbenzene dehydrogenation. The first is one-dimensional model, considered axial gradient only while the second is two-dimensional model considered axial and radial gradients for same variables.The developed mathematical models consisted of nonlinear simultaneous equations in multiple dependent variables. A complete description of the reactor bed involves partial, ordinary differential and algebraic equations (PDEs, ODEs and AEs describing the temperatures, concentrations and pressure drop across the reactor was given. The model equations are solved by finite differences method. The reactor models were coded with Mat lab 6.5 program and various numerical techniques were used to obtain the desired solution.The simulation data for both models were validated with industrial reactor results with a very good concordance.

  9. Catalytic synthesis of 2-methylpyrazine over Cr-promoted copper based catalyst via a cyclo-dehydrogenation reaction route

    Indian Academy of Sciences (India)

    Fangli Jing; Yuanyuan Zhang; Shizhong Luo; Wei Chu; Hui Zhang; Xinyu Shi

    2010-07-01

    The cyclo-dehydrogenation of ethylene diamine and propylene glycol to 2-methylpyrazine was performed under the atmospheric conditions at 380°C. The Cr-promoted Cu-Zn/Al2O3 catalysts were prepared by impregnation method and characterized by ICP-AES, N2 adsorption/desorption, XRD, XPS, N2O chemisorption, TPR and NH3-TPD techniques. The amorphous chromium species existing in Cu-Zn-Cr/Al2O3 catalyst enhanced the dispersion of active component Cu, promoted the reduction of catalyst. Furthermore, the catalytic performance was significantly improved. The acidity of the catalyst played an important role in increasing the 2-MP selectivity. To optimize the reaction parameters, influences of different chromium content, reaction temperature, liquid hourly space velocity (LHSV), reactants molar ratio and time on stream on the product pattern were studied. The results demonstrated that addition of chromium promoter revealed satisfying catalytic activity, stability and selectivity of 2-methylpyrazine.

  10. A Moessbauer spectroscopic study on the action of Ce in the catalyst for dehydrogenation of etylbenzene to styrene

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Keyu, E-mail: keyujiang@126.com [East China Normal University, Department of Physics (China); Fan Qin; Chen Tong; Miao Changxi [Shanghai Research Institute of Petrochemical Technology, SINOPEC (China); Zhao Zhenji; Yang Xielong [East China Normal University, Department of Physics (China)

    2012-03-15

    Two series of Fe-K catalysts for dehydrogenation of ethylbenzene to styrene were prepared with different amounts and different compounds of the additional element Ce. Moessbauer spectroscopy has been used to determine the Fe compound in the catalyst and to investigate the effect of Ce. The catalytic properties of the catalysts have also been measured. The results show that the element Ce in the catalyst is favorable to form the predecessor of the catalytic active phase, the compound KFe{sub 11}O{sub 17} and that the optimal percentage of CeO{sub 2} is 8%{approx}15% in the catalyst which is favorable to the formation of KFe{sub 11}O{sub 17} and to get better catalytic properties.

  11. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    Science.gov (United States)

    Seffer, J.-F.; Detriche, S.; Nagy, J. B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR3) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl2 catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  12. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    Energy Technology Data Exchange (ETDEWEB)

    Seffer, J.-F., E-mail: jean-francois.seffer@unamur.be; Detriche, S.; Nagy, J.B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR{sup ′}{sub 3}) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl{sub 2} catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  13. Novel mesoporous mixed Nb-M (M = V, Mo, and Sb) oxides for oxidative dehydrogenation of propane.

    Science.gov (United States)

    Yuan, Li; Bhatt, Salil; Beaucage, Gregory; Guliants, Vadim V; Mamedov, Sergey; Soman, Rajiv S

    2005-12-15

    Novel thermally stable mesoporous mixed metal Nb-M (M = V, Mo and Sb) oxides were synthesized in the presence of a nonionic Pluronic P123 surfactant. These oxides displayed promising pore structures and chemical compositions for selective oxidative functionalization of propane: high surface areas (up to 200 m2/g), large pore sizes (5-14 nm), and high pore volumes (up to 0.46 cm3/g). The oxidative dehydrogenation of propane to propylene over mesoporous mixed metal Nb-M oxides employed as a probe reaction suggested that the M component was dispersed as the molecular surface species and also formed a solid solution with NbOx in the inorganic walls of these mesoporous mixed metal oxides.

  14. Cluster-derived Ir-Sn/SiO2 catalysts for the catalytic dehydrogenation of propane: A spectroscopic study

    KAUST Repository

    Gallo, Alessandro

    2013-01-01

    Ir-Sn bimetallic silica-based materials have been prepared via deposition of the molecular organometallic clusters (NEt4)2[Ir 4(CO)10(SnCl3)2] and NEt 4[Ir6(CO)15(SnCl3)] or via deposition of Sn organometallic precursor Sn(n-C4H9) 4 onto pre-formed Ir metal particles. These solids possess promising properties, in terms of selectivity, as catalysts for propane dehydrogenation to propene. Detailed CO-adsorption DRIFTS, XANES and EXAFS characterization studies have been performed on these systems in order to compare the structural and electronic evolution of systems in relation to the nature of the Ir-Sn bonds present in the precursor compounds and to propose a structural model of the Ir-Sn species present at the silica surface of the final catalyst. © 2013 The Royal Society of Chemistry.

  15. Influence of phosphorous addition on Bi3Mo2Fe1 oxide catalysts for the oxidative dehydrogenation of 1-butene

    KAUST Repository

    Park, Jung-Hyun

    2016-01-22

    Bi3Mo2Fe1Px oxide catalysts were prepared by a co-precipitation method and the influence of phosphorous content on the catalytic performance in the oxidative dehydrogenation of 1-butene was investigated. The addition of phosphorous up to 0.4mole ratio to Bi3Mo2Fe1 oxide catalyst led to an increase in the catalytic performance; however, a higher phosphorous content (above P=0.4) led to a decrease of conversion. Of the tested catalysts, Bi3Mo2Fe1P0.4 oxide catalyst exhibited the highest catalytic performance. Characterization results showed that the catalytic performance was related to the quantity of a π-allylic intermediate, facile desorption behavior of adsorbed intermediates and ability for re-oxidation of catalysts. © 2015 Korean Institute of Chemical Engineers, Seoul, Korea

  16. Pressure Drop and Catalytic Dehydrogenation of NaBH{sub 4} Solution Across Pin Fin Structures in a Microchannel Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Ki Moon [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of); Choi, Seok Hyun [Key Valve Technologies Ltd., Siheung (Korea, Republic of); Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2017-06-15

    Dehydrogenation from the hydrolysis of a sodium borohydride (NaBH{sub 4}) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.%) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a NaBH4 solution over both a single microchannel with a hydraulic diameter of 300 μm and a staggered array of micro pin fins in the microchannel with hydraulic diameter of 50 μm. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.%. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

  17. Oxidative dehydrogenation of ethane over RE-NiO (RE=La, Nd, Sm, Gd)catalysts

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qin; ZHOU Dishan; WU Ying; WU Tinghua

    2013-01-01

    RE-NiO (RE=La,Nd,Sm,Gd) catalysts were prepared by a modified sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),BET surface area analysis,H2 temperature-programmed reduction (H2-TPR),and O2 temperature-programmed desorption (O2-TPD).The oxidative dehydrogenation of ethane (ODHE) to ethylene was applied to evaluate catalytic performance of the samples.The results showed that the doping of RE affected the physicochemical properties of the catalysts.The strong interaction between Gd and NiO played an important role in the lessened reducibility and the distribution of adsorbed oxygen species,consequently influenced the catalytic performance.The best yield to ethylene of 29% was obtained over the Gd-NiO catalyst with an ethane conversion of 56%.

  18. Genotypic and phenotypic spectrum of pyridoxine-dependent epilepsy (ALDH7A1 deficiency)

    DEFF Research Database (Denmark)

    Mills, Philippa B; Footitt, Emma J; Mills, Kevin A

    2010-01-01

    Pyridoxine-dependent epilepsy was recently shown to be due to mutations in the ALDH7A1 gene, which encodes antiquitin, an enzyme that catalyses the nicotinamide adenine dinucleotide-dependent dehydrogenation of l-alpha-aminoadipic semialdehyde/L-Delta1-piperideine 6-carboxylate. However, whilst...... with suspected or clinically proven pyridoxine-dependent epilepsy and to characterize further the phenotypic spectrum of antiquitin deficiency. Urinary L-alpha-aminoadipic semialdehyde concentration was determined by liquid chromatography tandem mass spectrometry. When this was above the normal range, DNA......, through abnormal foetal movements and a multisystem neonatal disorder, to the onset of seizures and autistic features after the first year of life. Our relatively large series suggested that clinical diagnosis of pyridoxine dependent epilepsy can be challenging because: (i) there may be some response...

  19. Synergic catalytic effect of Ti hydride and Nb nanoparticles for improving hydrogenation and dehydrogenation kinetics of Mg-based nanocomposite

    Directory of Open Access Journals (Sweden)

    Xiujuan Ma

    2017-02-01

    Full Text Available The Mg-9.3 wt% (TiH1.971-TiH−0.7 wt% Nb nanocomposite has been synthesized by hydrogen plasma-metal reaction (HPMR approach to enhance the hydrogen sorption kinetics of Mg at moderate temperatures by providing nanosizing effect of increasing H “diffusion channels” and adding transition metallic catalysts. The Mg nanoparticles (NPs were in hexagonal shape range from 50 to 350 nm and the average size of the NPs was 177 nm. The small spherical TiH1.971, TiH and Nb NPs of about 25 nm uniformly decorated on the surface of the big Mg NPs. The Mg-TiH1.971-TiH-Nb nanocomposite could quickly absorb 5.6 wt% H2 within 5 min at 573 K and 4.5 wt% H2 within 5 min at 523 K, whereas the pure Mg prepared by HPMR could only absorb 4 and 1.5 wt% H2 at the same temperatures. TiH1.971, TiH and Nb NPs transformed into TiH2 and NbH during hydrogenation and recovered after dehydrogenation process. The apparent activation energies of the nanocomposite for hydrogenation and dehydrogenation were 45.0 and 50.7 kJ mol−1, which are much smaller than those of pure Mg NPs, 123.8 and 127.7 kJ mol−1. The improved sorption kinetics of the Mg-based nanocomposite at moderate temperatures and the small activation energy can be interpreted by the nanostructure of Mg and the synergic catalytic effects of Ti hydrides and Nb NPs.

  20. Sn surface-enriched Pt-Sn bimetallic nanoparticles as a selective and stable catalyst for propane dehydrogenation

    KAUST Repository

    Zhu, Haibo

    2014-12-01

    A new one pot, surfactant-free, synthetic route based on the surface organometallic chemistry (SOMC) concept has been developed for the synthesis of Sn surface-enriched Pt-Sn nanoparticles. Bu3SnH selectively reacts with [Pt]-H formed in situ at the surface of Pt nanoparticles, Pt NPs, obtained by reduction of K2PtCl4 by LiB(C2H5)3H. Chemical analysis, 1H MAS and 13C CP/MAS solid-state NMR as well as two-dimensional double-quantum (DQ) and triple-quantum (TQ) experiments show that organo-tin moieties Sn(n-C4H9) are chemically linked to the surface of Pt NPs to produce, in fine, after removal of most of the n-butyl fragment, bimetallic Pt-Sn nanoparticles. The Sn(n-CH2CH2CH2CH3) groups remaining at the surface are believed to stabilize the as-synthesized Pt-Sn NPs, enabling the bimetallic NPs to be well dispersed in THF. Additionally, the Pt-Sn nanoparticles can be supported on MgAl2O4 during the synthesis of the nanoparticles. Some of the Pt-Sn/MgAl2O4 catalyst thus prepared exhibits high activity in PROX of CO and an extremely high selectivity and stability in propane dehydrogenation to propylene. The enhanced activity in propane dehydrogenation is associated with the high concentration of inactive Sn at the surface of Pt nanoparticles which ”isolates” the active Pt atoms. This conclusion is confirmed by XRD, NMR, TEM, and XPS analysis.

  1. Characterization of Industrial Pt-Sn/Al2O3 Catalyst and Transient Product Formations during Propane Dehydrogenation

    Directory of Open Access Journals (Sweden)

    Kah Sing Ho

    2013-06-01

    Full Text Available The major problem plaguing propane dehydrogenation process is the coke formation on the Pt-Sn/Al2O3 catalyst which leads to catalyst deactivation. Due to information paucity, the physicochemical characteristics of the commercially obtained regenerated Pt-Sn/Al2O3 catalyst (operated in moving bed reactor and coke formation at different temperatures of reaction were discussed. The physicochemical characterization of regenerated catalyst gave a BET surface area of 104.0 m2/g with graphitic carbon content of 8.0% indicative of incomplete carbon gasification during the industrial propylene production. Effect of temperatures on coke formation was identified by studying the product yield via temperature-programmed reaction carried out at 500oC, 600oC and 700oC. It was found that ethylene was precursor to carbon laydown while propylene tends to crack into methane. Post reaction, the spent catalyst possessed relatively lower surface area and pore radius whilst exhibited higher carbon content (31.80% at 700oC compared to the regenerated catalyst. Significantly, current studies also found that higher reaction temperatures favoured the coke formation. Consequently, the propylene yield has decreased with reaction temperature. © 2013 BCREC UNDIP. All rights reservedReceived: 10th March 2013; Revised: 28th April 2013; Accepted: 6th May 2013[How to Cite: Kah, S.H., Joanna Jo, E.C., Sim, Y.C., Chin, K.C. (2013. Characterization of Industrial Pt-Sn/Al2O3 Catalyst and Transient Product Formations during Propane Dehydrogenation. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 77-82. (doi:10.9767/bcrec.8.1.4569.77-82][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4569.77-82] | View in  |

  2. Kinetics of propane dehydrogenation in CO{sub 2} presence over chromium and gallium oxide catalysts based on MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Gaidai, N.A.; Nekrasov, N.V.; Agafonov, A.Yu.; Botavina, M.A. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2012-07-01

    Chromium and gallium catalysts based on MCM-41 with different contents of active metals were prepared and tested for propane dehydrogenation in the presence and absence of CO{sub 2}. It was shown that CO{sub 2} increased the yield of propene and decreased considerably the rate of deactivation of Cr/MCM-41 and decreased propene yield and slightly improved the stability of Ga/MCM-41. The study of kinetics in unstationary and stationary fields showed that the decrease of propene yield was connected with strong competitive adsorption of CO{sub 2} over Ga-catalysts what presented difficulties for propane adsorption. The formation of cracking products was decreased in CO{sub 2} presence over both catalysts. The catalysts were differed by the adsorption capacity of the reaction components: C{sub 3}H{sub 6} was tied more strongly than CO{sub 2} over Cr-catalysts, CO{sub 2} was tied more firmly than C{sub 3}H{sub 6} over Ga-catalysts. Kinetic data showed that of H{sub 2} was bounded with the surface of Ga-catalysts very firmly, reverse watergas shift reaction proceeded in considerably more extent over Cr-catalysts than over Gaones. CO{sub 2} took active participation in oxidation of coke and surface of Cr-catalysts. The positive role of CO{sub 2} in propane dehydrogenation over Ga-catalysts consisted in a decrease of coke and cracking products. Kinetic equations and step-schemes for propene and cracking products formation were proposed. (orig.)

  3. Lipid-storage myopathy and respiratory insufficiency due to ETFQO mutations in a patient with late-onset multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke Katrine Jentoft; Pourfarzam, M; Morris, A A M;

    2004-01-01

    response to treatment, she developed respiratory insufficiency at age 14 years and has required long-term overnight ventilation. Thus, MADD is one of the few conditions that can cause a myopathy with weakness of the respiratory muscles out of proportion to the limb muscles. Udgivelsesdato: 2004-null...

  4. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... severity of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may ...

  5. Factor II deficiency

    Science.gov (United States)

    ... if one or more of these factors are missing or are not functioning like they should. Factor II is one such coagulation factor. Factor II deficiency runs in families (inherited) and is very rare. Both parents must ...

  6. Factor VII deficiency

    Science.gov (United States)

    ... if one or more of these factors are missing or are not functioning like they should. Factor VII is one such coagulation factor. Factor VII deficiency runs in families (inherited) and is very rare. Both parents must ...

  7. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... of Intramural Research Research Resources Research Meeting Summaries Technology Transfer Clinical Trials What Are Clinical Trials? Children & ... of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require ...

  8. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-rich protein that carries oxygen from the lungs to the rest of the body. Iron-deficiency ... 2011 This video—presented by the National Heart, Lung, and Blood Institute, part of the National Institutes ...

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL TRIALS LINKS Related Topics ... Doctors usually can successfully treat iron-deficiency anemia. Treatment will depend on the cause and severity of ...

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... deficiency anemia may require treatment in a hospital, blood transfusions , iron injections, or intravenous iron therapy. Rate This ... video—presented by the National Heart, Lung, and Blood Institute, part of the National ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... such as tiredness, poor skin tone, dizziness, and depression. After her doctor diagnosed her with iron-deficiency ... to stop her monthly periods. By following her treatment plan and making smart lifestyle choices, Susan continues ...

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Digg. Share this page from the NHLBI on Facebook. Add this link to the NHLBI to my ... Deficiency Anemia article. Updated: March 26, 2014 Twitter Facebook YouTube Google+ SITE INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA ...

  13. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... chest pain, and other symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, and other complications. Infants and young children and ...

  14. Iron-Deficiency Anemia

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    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... food. Overview Iron-deficiency anemia is a common type of anemia . The term "anemia" usually refers to ...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... the body. Iron-deficiency anemia usually develops over time if your body doesn't have enough iron ...

  16. Sleep Deprivation and Deficiency

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Are Sleep Deprivation and Deficiency? Sleep deprivation (DEP-rih-VA- ... Rate This Content: NEXT >> Updated: June 7, 2017 Sleep Infographic Sleep Disorders & Insufficient Sleep: Improving Health through ...

  17. Iron-Deficiency Anemia

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    Full Text Available ... chest pain, and other symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, and other complications. Infants and young children and ...

  18. Iron-Deficiency Anemia

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    Full Text Available ... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL TRIALS LINKS Related Topics ... Doctors usually can successfully treat iron-deficiency anemia. Treatment will depend on the cause and severity of ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... a waste product) from your body. Anemia also can occur if your red blood cells don't ... have less hemoglobin than normal. Iron-deficiency anemia can cause fatigue (tiredness), shortness of breath, chest pain, ...

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Intramural Research Research Resources Research Meeting Summaries Technology Transfer Clinical Trials What Are Clinical Trials? Children & Clinical ... iron-deficiency anemia may require treatment in a hospital, blood transfusions , iron injections, or intravenous iron therapy. ...

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in ... 18/2011 This video—presented by the National Heart, Lung, and Blood Institute, part of the National ...

  2. Iron-Deficiency Anemia

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    Full Text Available ... of breath, chest pain, and other symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, and other complications. Infants and young children and ...

  3. Iron-Deficiency Anemia

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    Full Text Available ... Digg. Share this page from the NHLBI on Facebook. Add this link to the NHLBI to my ... Deficiency Anemia article. Updated: March 26, 2014 Twitter Facebook YouTube Google+ SITE INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA ...

  4. Iron deficiency anemia

    OpenAIRE

    Naigamwalla, Dinaz Z.; Webb, Jinelle A.; Giger, Urs

    2012-01-01

    Iron is essential to virtually all living organisms and is integral to multiple metabolic functions. The most important function is oxygen transport in hemoglobin. Iron deficiency anemia in dogs and cats is usually caused by chronic blood loss and can be discovered incidentally as animals may have adapted to the anemia. Severe iron deficiency is characterized by a microcytic, hypochromic, potentially severe anemia with a variable regenerative response. Iron metabolism and homeostasis will be ...

  5. Proximal Focal Femoral Deficiency

    OpenAIRE

    Vishal Kalia, Vibhuti

    2008-01-01

    Proximal focal femoral deficiency (PFFD) is a developmental disorder of the proximal segment of thefemur and of acetabulum resulting in shortening of the affected limb and impairment of the function. It isa spectrum of congenital osseous anomalies characterized by a deficiency in the structure of the proximalfemur. The diagnosis is often made by radiological evaluation which includes identification and descriptionof PFFD and evaluation of associated limb anomalies by plain radiographs. Contra...

  6. Glucose-6-phosphatase deficiency.

    OpenAIRE

    Labrune Philippe; Gajdos Vincent; Eberschweiler Pascale; Hubert-Buron Aurélie; Petit François; Vianey-Saban Christine; Boudjemline Alix; Piraud Monique; Froissart Roseline

    2011-01-01

    Abstract Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, betw...

  7. Vitamin B12 deficiency.

    Science.gov (United States)

    Oh, Robert; Brown, David L

    2003-03-01

    Vitamin B12 (cobalamin) deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders. The role of B12 deficiency in hyperhomocysteinemia and the promotion of atherosclerosis is only now being explored. Diagnosis of vitamin B12 deficiency is typically based on measurement of serum vitamin B12 levels; however, about 50 percent of patients with subclinical disease have normal B12 levels. A more sensitive method of screening for vitamin B12 deficiency is measurement of serum methylmalonic acid and homocysteine levels, which are increased early in vitamin B12 deficiency. Use of the Schilling test for detection of pernicious anemia has been supplanted for the most part by serologic testing for parietal cell and intrinsic factor antibodies. Contrary to prevailing medical practice, studies show that supplementation with oral vitamin B12 is a safe and effective treatment for the B12 deficiency state. Even when intrinsic factor is not present to aid in the absorption of vitamin B12 (pernicious anemia) or in other diseases that affect the usual absorption sites in the terminal ileum, oral therapy remains effective.

  8. Influence of the pressure on the product distribution in the oxidative dehydrogenation of propane over a Ga2O3/MoO3 catalystInfluence of the pressure on the product distribution in the oxidative dehydrogenation of propane over a Ga2O3/MoO3 catalyst

    NARCIS (Netherlands)

    Kotanjac, Z. S.; Niederer, J. P. M.; Versteeg, G. F.

    2007-01-01

    The yields and selectivities in both the catalyzed and non-catalyzed oxidative dehydrogenation of propane were found to increase with increasing pressure. The results showed that the maximum yields of valuable ODH products could be obtained by adjusting only reactants' partial pressure, while

  9. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  10. Inlfuence of the Alkali Treatment of HZSM-5 Zeolite on Catalytic Performance of PtSn-Based Catalyst for Propane Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Huang Li; Zhou Shijian; Zhou Yuming; Zhang Yiwei; Xu Jun; Wang Li

    2013-01-01

    The porous material ATZ with micro-mesopore hierarchical porosity was prepared by alkali treatment of parent HZSM-5 zeolite and applied for propane dehydrogenation. The zeolite samples were characterized by XRD, N2-physisorption, and NH3-TPD analysis. The results showed that the alkali treatment can modify the physicochemical prop-erties of HZSM-5 zeolite. In this case, the porous material ATZ showed larger external surface area with less acid sites as compared to the HZSM-5 zeolite. It was found out that the alkali treatment of HZSM-5 zeolite could promote the catalytic performance of PtSn/ATZ catalyst. The possible reason was ascribed to the low acidity of ATZ. Furthermore, the presence of mesopores could reduce the carbon deposits on the metallic surface, which was also favorable for the dehydrogenation reaction.

  11. DH-2型脱氢催化剂的使用及维护%Use and Maintenance of DH-2 Dehydrogenation Catalyst

    Institute of Scientific and Technical Information of China (English)

    任玉兵

    2014-01-01

    介绍CO2汽提法尿素装置应用DH‐2型脱氢催化剂的情况,包括脱氢原理、工艺操作指标、催化剂装填、运行中的注意事项、影响其活性的因素,以及异常情况的处理等。%Describe the use of the DH‐2 dehydrogenation catalyst in the CO2 stripping urea plant , w hich including the dehydrogenation mechanism , the process operation index , the catalyst loading , the operation precautions , the catalyst activity affecting factor and the abnormal situation handling , etc .

  12. Dehydrogenation properties and mechanisms of MgH2-NiCl2 and MgH2-NiCl2-graphene hydrogen storage composites

    Science.gov (United States)

    Zhang, J.; Qu, H.; Yan, S.; Yin, L. R.; Zhou, D. W.

    2017-07-01

    The four hydrogen storage systems including pure MgH2, MgH2-5 wt%NiCl2, MgH2-10 wt%NiCl2 and MgH2-10 wt%NiCl2-10 wt%graphene were prepared by ball-milling in this work. Using experimental X-ray diffraction, scanning electron microscopy and differential scanning calorimetry testing methods in combination with first-principle calculations, the dehydrogenation properties and mechanisms of NiCl2 single-doped and NiCl2-graphene co-doped MgH2 composites were systematically investigated. Experimental results show that the NiCl2 single-doping is conductive to decreasing the size of MgH2 grains and particles. The co-doping of NiCl2 and graphene not only reduces the size of MgH2 grains and particles, but also contributes to the uniformity of MgH2 particles. As compared with milled pure MgH2, the dehydrogenation peak temperatures are decreased by 24 °C and 47 °C for the 10 wt%NiCl2 single-doped and 10 wt%NiCl2-10 wt%graphene co-doped MgH2 systems, respectively. It is demonstrated that the co-doping of NiCl2 and graphene exhibits the synergistic effects of confinement and catalysis on improving the dehydrogenation properties of MgH2. The first-principle calculations indicate that the co-doping of NiCl2 and graphene leads to the distortion of MgH2 atomic-configuration and results in the charge transfer between the dopants and MgH2, which induce the weakened structural stability and decreased dehydrogenation enthalpy of MgH2.

  13. Unexpected dehydrogenation behaviors of the 2LiBH4-MgH 2 composite confined in a mesoporous carbon scaffold

    CSIR Research Space (South Africa)

    Wang, K

    2014-11-01

    Full Text Available on the reversible dehydrogenation property and reaction mechanism pathway of the 2LiBH(sub4)–MgH(sub2) composite system. Compared to the bulk 2LiBH(sub4)–MgH(sub2) composite, the 2LiBH(sub4)–MgH(sub2) confined in the mesoporous carbon (CMK-3) scaffold host exhibits...

  14. Dehydrogenative [2 + 2 + 1] Heteroannulation Using a Methyl Group as a One-Carbon Unit: Access to Pyrazolo[3,4-c]quinolines.

    Science.gov (United States)

    Deng, Guo-Bo; Li, Hai-Bing; Yang, Xu-Heng; Song, Ren-Jie; Hu, Ming; Li, Jin-Heng

    2016-05-06

    A practical and straightforward access to pyrazolo[3,4-c]quinolines by molecular sieve mediated dehydrogenative [2 + 2 + 1] heteroannulation of N-(o-alkenylaryl)imines with aryldiazonium salts is described using a sp(3)-hybrid carbon atom as a one-carbon unit. The reaction enables the formation of three new chemical bonds, a C-C bond and two C-N bonds, in a single reaction and features simple operation and excellent functional group tolerance.

  15. Dehydrogenation kinetics, reversibility, and reaction mechanisms of reversible hydrogen storage material based on nanoconfined MgH2-NaAlH4

    Science.gov (United States)

    Plerdsranoy, Praphatsorn; Meethom, Sukanya; Utke, Rapee

    2015-12-01

    Studies of dehydrogenation kinetics, reversibility, and reaction mechanisms during de/rehydrogenation of nanoconfined MgH2-NaAlH4 into carbon aerogel scaffold (CAS) for reversible hydrogen storage material are for the first time proposed. Two different MgH2:NaAlH4 molar ratios (1:1 and 2:1) of hydride composite are melt infiltrated into CAS under 1:1 (CAS:hydride composite) weight ratio. Successful nanoconfinement is confirmed by N2 adsorption-desorption. Multiple-step dehydrogenation of milled samples is reduced to two-step reaction due to nanoconfinement. Peak temperatures corresponding to main dehydrogenation of nanoconfined samples significantly reduce as compared with those of milled samples, i.e., ∆T=up to 50 and 34 °C for nanoconfined sample with 1:1 and 2:1 (MgH2:NaAlH4) molar ratios, respectively. Hydrogen content released (the 1st cycle) and reproduced (the 2nd, 3rd, and 4th cycles) of nanoconfined samples enhance up to 80% and 68% with respect to theoretical hydrogen storage capacity, respectively, while those of milled samples are 71% and 38%, respectively. Remarkable hydrogen content reproduced after nanoconfinement is due to the fact that metallic Al obtained after dehydrogenation (T=300 °C under vacuum) of nanoconfined samples prefer to react with MgH2 and produces Al12Mg17, favorable for reversibility of MgH2-NaAlH4 system, whereas that of milled samples stays in the form of unreacted Al under the same temperature and pressure condition.

  16. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen

    Directory of Open Access Journals (Sweden)

    Bashir Ahmad Dar

    2012-06-01

    Full Text Available The present work is intended to determine the catalytic activity of Mixed Oxide supported gold for aerobic oxidative dehydrogenation of amines to imines using Ceria as a main constituent of the each support. The model catalysts Au/CeO2:TiO2 Au/CeO2:SiO2, Au/CeO2:ZrO2 and Au/CeO2:Al2Os were prepared by deposition co-precipitation method and deposition of gold was determined by EDEX analysis. The supported nano-gold catalyzes the dehydrogenation of secondary amines to imines without loss of activity. On recycling good amount of product yield is obtained. Oxidation of secondary amines to imines is carried at 100˚C and almost 90 % conversion was obtained with >99% selectivity. © 2012 BCREC UNDIP. All rights reservedReceived: 26th December 2011; Revised: 7th June 2012; Accepted: 13rd June 2012[How to Cite: B.A. Dar, M. Sharma, B. Singh. (2012. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen. Bulletin of Chemical Reaction Engineering & Catalysis, 7(1: 79-84.  doi:10.9767/bcrec.7.1.1257.79-84][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1257.79-84 ] | View in 

  17. Ultraviolet-Visible (UV-Vis) Microspectroscopic System Designed for the In Situ Characterization of the Dehydrogenation Reaction Over Platinum Supported Catalytic Microchannel Reactor.

    Science.gov (United States)

    Suarnaba, Emee Grace Tabares; Lee, Yi Fuan; Yamada, Hiroshi; Tagawa, Tomohiko

    2016-11-01

    An ultraviolet visible (UV-Vis) microspectroscopic system was designed for the in situ characterization of the activity of the silica supported platinum (Pt) catalyst toward the dehydrogenation of 1-methyl-1,4-cyclohexadiene carried out in a custom-designed catalytic microreactor cell. The in situ catalytic microreactor cell (ICMC) with inlet/outlet ports was prepared using quartz cover as the optical window to facilitate UV-Vis observation. A fabricated thermometric stage was adapted to the UV-Vis microspectrophotometer to control the reaction temperature inside the ICMC. The spectra were collected by focusing the UV-Vis beam on a 30 × 30 µm area at the center of ICMC. At 393 K, the sequential measurement of the spectra recorded during the reaction exhibited a broad absorption peak with maximum absorbance at 260 nm that is characteristic for gaseous toluene. This result indicates that the silica supported Pt catalyst is active towards the dehydrogenation of 1-methyl-1,4-cyclohexadiene at the given experimental conditions. The onset of coke formation was also detected based on the appearance of absorption bands at 300 nm. The UV-Vis microspectroscopic system developed can be used further in studying the mechanism of the dehydrogenation reaction. © The Author(s) 2016.

  18. Dehydrogenation kinetics of pure and nickel-doped magnesium hydride investigated by in situ time-resolved powder X-ray diffraction

    DEFF Research Database (Denmark)

    Jensen, T.R.; Andreasen, A.; Vegge, Tejs;

    2006-01-01

    conditions. A quartz capillary cell allowed the in situ study of gas/solid reactions. Three phases were identified: Mg, MgH2 and MgO and their phase fractions were extracted by Rietveld refinement or integration of selected reflections from each phase. Dehydrogenation curves were constructed and analysed...... by the Johnson-Mehi-Avrami formalism in order to derive rate constants at different temperatures. The apparent activation energies for dehydrogenation of pure and Ni-doped magnesium hydride were E-A approximate to 300 and 250 kJ/mol, respectively. Differential scanning calorimetry gave, E-A = 270 k......J/mol for dehydrogenation of the Ni-doped sample. The relatively high activation energies are due to MgO surface layers, retarding the diffusion of hydrogen (H-2) out of MgH2/Mg. The observed difference in E-A of ca. 50 kJ/moI is likely due to the catalytic effect of Ni on the recombination of H atoms to H-2 molecules...

  19. Aqueous solution synthesis of Pt-M (M = Fe, Co, Ni) bimetallic nanoparticles and their catalysis for the hydrolytic dehydrogenation of ammonia borane.

    Science.gov (United States)

    Wang, Shuai; Zhang, Duo; Ma, Yanyun; Zhang, Hui; Gao, Jing; Nie, Yuting; Sun, Xuhui

    2014-08-13

    Platinum-based bimetallic nanocatalysts have attracted much attention due to their high-efficiency catalytic performance in energy-related applications such as fuel cell and hydrogen storage, for example, the hydrolytic dehydrogenation of ammonia borane (AB). In this work, a simple and green method has been demonstrated to successfully prepare Pt-M (M = Fe, Co, Ni) NPs with tunable composition (nominal Pt/M atomic ratios of 4:1, 1:1, and 1:4) in aqueous solution under mild conditions. All Pt-M NPs with a small size of 3-5 nm show a Pt fcc structure, suggesting the bimetallic formation (alloy and/or partial core-shell), examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS) analysis. The catalytic activities of Pt-M NPs in the hydrolytic dehydrogenation of AB reveal that Pt-Ni NPs with a ratio of 4:1 show the best catalytic activity and even better than that of pure Pt NPs when normalized to Pt molar amount. The Ni oxidation state in Pt-Ni NPs has been suggested to be responsible for the corresponding catalytic activity for hydrolytic dehydrogenation of AB by XAFS study. This strategy for the synthesis of Pt-M NPs is simple and environmentally benign in aqueous solution with the potential for scale-up preparation and the in situ catalytic reaction.

  20. Reaction of niobium and tantalum neutral clusters with low pressure, unsaturated hydrocarbons in a pickup cell: From dehydrogenation to Met-Car formation

    Science.gov (United States)

    He, S.-G.; Xie, Y.; Dong, F.; Bernstein, E. R.

    2006-10-01

    Neutral niobium and tantalum clusters (Nbn and Tan) are generated by laser ablation and supersonic expansion into a vacuum and are reacted in a pickup cell with various low pressure (˜1mTorr) unsaturated hydrocarbons (acetylene, ethylene, propylene, 1-butene, 1,3-butadiene, benzene, and toluene) under nearly single collision conditions. The bare metal clusters and their reaction products are ionized by a 193nm laser and detected by a time of flight mass spectrometer. Partially and fully dehydrogenated products are observed for small (n⩽m) and large (n⩾m) neutral metal clusters, respectively, with m ranging from 2 to 5 depending on the particular hydrocarbon. In addition to primary, single collision products, sequential addition products that are usually fully dehydrogenated are also observed. With toluene used as the reactant gas, carbon loss products are observed, among which Nb8C12 and Ta8C12 are particularly abundant, indicating that the Met-Car molecule M8C12 can be formed from the neutral metal cluster upon two collisions with toluene molecules. The dehydrogenation results for low pressure reactions are compared with those available from previous studies employing flow tube (high pressure) reactors. Low pressure and high pressure cluster ion reactions are also compared with the present neutral metal cluster reactions. Reactions of unsaturated hydrocarbons and metal surfaces are discussed in terms of the present neutral cluster results.

  1. Insights into dehydrogenative coupling of alcohols and amines catalyzed by a (PNN)-Ru(II) hydride complex: unusual metal-ligand cooperation.

    Science.gov (United States)

    Zeng, Guixiang; Li, Shuhua

    2011-11-07

    Density functional theory calculations were performed to elucidate the mechanism of dehydrogenative coupling of primary alcohols and amines mediated by a PNN-Ru(II) hydride complex (PNN = (2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)pyridine)). A plausible reaction pathway was proposed which contains three stages: (1) The alcohol dehydrogenation reaction to generate the aldehyde and H(2); (2) The aldehyde-amine condensation reaction to form the hemiaminal intermediate; (3) The dehydrogenation process of the hemiaminal intermediate to yield the final amide product with the liberation of H(2). The first and third stages occur via a similar pathway: (a) Proton transfer from the substrate to the PNN ligand; (b) Intramolecular rearrangement of the deprotonated substrate to form an anagostic complex; (c) Hydride transfer from the deprotonated substrate to the Ru center to yield the trans-dihydride intermediate and the aldehyde (or amide); (d) Benzylic proton migration from the PNN ligand to the metal center forming a dihydrogen complex and subsequent H(2) liberation to regenerate the catalyst. In all these steps, the metal-ligand cooperation plays an essential role. In proton transfer steps (a) and (d), the metal-ligand cooperation is achieved through the aromatization/dearomatization processes of the PNN ligand. While in steps (b) and (c), their collaboration are demonstrated by the formation of an anagostic interaction between Ru and the C-H bond and two ionic hydrogen bonds supported by the PNN ligand.

  2. Density functional investigations of electronic structure and dehydrogenation reactions of Al- and Si-substituted magnesium hydride.

    Science.gov (United States)

    Kelkar, Tuhina; Pal, Sourav; Kanhere, Dilip G

    2008-04-21

    The effect on the hydrogen storage attributes of magnesium hydride (MgH(2)) of the substitution of Mg by varying fractions of Al and Si is investigated by an ab initio plane-wave pseuodopotential method based on density functional theory. Three supercells, namely, 2 x 2 x 2, 3 x 1 x 1 and 5 x 1 x 1 are used for generating configurations with varying amounts (fractions x=0.0625, 0.1, and 0.167) of impurities. The analyses of band structure and density of states (DOS) show that, when a Mg atom is replaced by Al, the band gap vanishes as the extra electron occupies the conduction band minimum. In the case of Si-substitution, additional states are generated within the band gap of pure MgH(2)-significantly reducing the gap in the process. The reduced band gaps cause the Mg--H bond to become more susceptible to dissociation. For all the fractions, the calculated reaction energies for the stepwise removal of H(2) molecules from Al- and Si-substituted MgH(2) are much lower than for H(2) removal from pure MgH(2). The reduced stability is also reflected in the comparatively smaller heats of formation (DeltaH(f)) of the substituted MgH(2) systems. Si causes greater destabilization of MgH(2) than Al for each x. For fractions x=0.167 of Al, x=0.1, 0.167 of Si (FCC) and x=0.0625, 0.1 of Si (diamond), DeltaH(f) is much less than that of MgH(2) substituted by a fraction x=0.2 of Ti (Y. Song, Z. X. Guo, R. Yang, Mat. Sc. & Eng. A 2004, 365, 73). Hence, we suggest the use of Al or Si instead of Ti as an agent for decreasing the dehydrogenation reaction and energy, consequently, the dehydrogenation temperature of MgH(2), thereby improving its potential as a hydrogen storage material.

  3. Iron deficiency anaemia.

    Science.gov (United States)

    Lopez, Anthony; Cacoub, Patrice; Macdougall, Iain C; Peyrin-Biroulet, Laurent

    2016-02-27

    Anaemia affects roughly a third of the world's population; half the cases are due to iron deficiency. It is a major and global public health problem that affects maternal and child mortality, physical performance, and referral to health-care professionals. Children aged 0-5 years, women of childbearing age, and pregnant women are particularly at risk. Several chronic diseases are frequently associated with iron deficiency anaemia--notably chronic kidney disease, chronic heart failure, cancer, and inflammatory bowel disease. Measurement of serum ferritin, transferrin saturation, serum soluble transferrin receptors, and the serum soluble transferrin receptors-ferritin index are more accurate than classic red cell indices in the diagnosis of iron deficiency anaemia. In addition to the search for and treatment of the cause of iron deficiency, treatment strategies encompass prevention, including food fortification and iron supplementation. Oral iron is usually recommended as first-line therapy, but the most recent intravenous iron formulations, which have been available for nearly a decade, seem to replenish iron stores safely and effectively. Hepcidin has a key role in iron homoeostasis and could be a future diagnostic and therapeutic target. In this Seminar, we discuss the clinical presentation, epidemiology, pathophysiology, diagnosis, and acute management of iron deficiency anaemia, and outstanding research questions for treatment.

  4. [Vitamin deficiencies and hypervitaminosis].

    Science.gov (United States)

    Mino, M

    1999-10-01

    There have recently been very few deficiencies with respect to fat soluble and water soluble vitamins in Japan All-trans-retinoic acid as induction or maintenance treatment improves disease free and overall survival against acute promyelocytic leukemia. In the isolated vitamin E deficiencies gene mutation has been cleared for alpha-tocopherol transferprotein. Recently, a relation of nutritional vitamin K intake and senile osteoporosis in women was epidemiologically demonstrated on a prospective study. Thiamin was yet noticed as development of deficiency in alcoholism, while the importance of supplemental folic acid during pregnancy has become especially clear in light of studies showing that folic acid supplements reduce the risk of neural tube defects in the fetus. With respect to hypervitaminosis, the Council for Responsible Nutrition (CRN), USA, has established safe intakes by identifying the NOAEL (No Observed Adverse Effect Level) and LOAEL (Lowest Observed Adverse Effect Level). Summaries of NOAEL and LOAEL for individual vitamins were shown.

  5. Antepartum Ornithine Transcarbamylase Deficiency

    Directory of Open Access Journals (Sweden)

    Hitoshi Nakajima

    2014-11-01

    Full Text Available Ornithine transcarbamylase deficiency (OTCD is the most common type urea cycle enzyme deficiencies. This syndrome results from a deficiency of the mitochondrial enzyme ornithine transcarbamylase, which catalyzes the conversion of ornithine and carbamoyl phosphate to citrullin. Our case was a 28-year-old female diagnosed with OTCD following neurocognitive deficit during her first pregnancy. Although hyperammonemia was suspected as the cause of the patient's mental changes, there was no evidence of chronic liver disease. Plasma amino acid and urine organic acid analysis revealed OTCD. After combined modality treatment with arginine, sodium benzoate and hemodialysis, the patient's plasma ammonia level stabilized and her mental status returned to normal. At last she recovered without any damage left.

  6. Mortality and GH deficiency

    DEFF Research Database (Denmark)

    Stochholm, Kirstine; Gravholt, Claus Højbjerg; Laursen, Torben;

    2007-01-01

    OBJECTIVE: To estimate the mortality in Denmark in patients suffering from GH deficiency (GHD). DESIGN: Mortality was analyzed in 1794 GHD patients and 8014 controls matched on age and gender. All records in GHD patients were studied and additional morbidity noted. Patients were divided into chil......OBJECTIVE: To estimate the mortality in Denmark in patients suffering from GH deficiency (GHD). DESIGN: Mortality was analyzed in 1794 GHD patients and 8014 controls matched on age and gender. All records in GHD patients were studied and additional morbidity noted. Patients were divided...

  7. Effect of cerium addition on catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mengwei Xue; Yuming Zhou; Yiwei Zhang; Xuan Liu; Yongzheng Duan; Xiaoli Sheng

    2012-01-01

    The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNa/ZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD,BET,TEM,XPS.NH3-TPD,H2 chemisorption,TPR and TPO techniques.It has been found that with suitable amount of cerium addition,the platinum dispersion increased,while the carbon deposition tended to be eliminated easily.In these cases,the presence of cerium could not only realize the better distribution of metallic particles on the support,but also strengthen the interactions between Sn species and the support.Additionally,XPS spectra confirmed that more amounts of tin could exist in oxidized form,which was advantageous to the reaction.In our experiments,PtSnNaCe (1.1 wt%)/ZSM-5 catalyst exhibited the best catalytic performance.After running the reaction for 750 h,propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.

  8. An Intramolecular Silylene Borane Capable of Facile Activation of Small Molecules, Including Metal-Free Dehydrogenation of Water.

    Science.gov (United States)

    Mo, Zhenbo; Szilvási, Tibor; Zhou, Yu-Peng; Yao, Shenglai; Driess, Matthias

    2017-02-27

    The first single-component N-heterocyclic silylene borane 1 (LSi-R-BMes2 ; L=PhC(N(t) Bu)2 ; R=1,12-xanthendiyl spacer; Mes=2,4,6-Me3 C6 H2 ), acting as a frustrated Lewis pair (FLP) in small-molecule activation, can be synthesized in 65 % yields. Its HOMO is largely localized at the silicon(II) atom and the LUMO has mainly boron 2p character. In small-molecule activation 1 allows access to the intramolecular silanone-borane 3 featuring a Si=O→B interaction through reaction with O2 , N2 O, or CO2 , and formation of silanethione borane 4 from reaction with S8 . The Si(II) center in 1 undergoes immediate hydrogenation if exposed to H2 at 1 atm pressure in benzene, affording the silane borane 5-H2 , L(H2 )Si-R-BMes2 . Remarkably, no H2 activation occurs if the single silylene LSiPh and Mes3 B intermolecularly separated are exposed to dihydrogen. Unexpectedly, the pre-organized Si-B separation in 1 enables a metal-free dehydrogenation of H2 O to give the silanone-borane 3 as reactive intermediate.

  9. Dehydrogenation of ethane to ethylene via radical pathways enhanced by alkali metal based catalyst in oxysteam condition

    KAUST Repository

    Takanabe, Kazuhiro

    2016-08-21

    The dehydrogenation of ethane to ethylene in the presence of oxygen and water was conducted using Na2WO4/SiO2 catalyst at high temperatures. At 923 K, the conversion rate without water was proportional to ethane pressure and a half order of oxygen pressure, consistent with a kinetically relevant step where an ethane molecule is activated with dissociated oxygen on the surface. When water was present, the ethane conversion rate was drastically enhanced. An additional term in the rate expression was proportional to a quarter of the oxygen pressure and a half order of the water pressure. This mechanism is consistent with the quasi-equilibrated OH radical formation with subsequent ethane activation. The attainable yield can be accurately described by taking the water contribution into consideration. At high conversion levels at 1073 K, the C2H4 yield exceeded 60% in a single-pass conversion. The C2H4 selectivity was almost insensitive to the C2H6 and O2 pressures. © 2016 American Institute of Chemical Engineers.

  10. Kinetics of the Oxidative Dehydrogenation of Isobutane over Cr2O3/La2(CO3)3

    Institute of Scientific and Technical Information of China (English)

    Yanping Sun; Tracey A. Robson; Trevor C. Brown

    2002-01-01

    The oxidative dehydrogenation (ODH) of isobutane over Cr2O3/La2(CO3)3 has been investi-gated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reactionsteps can be accurately determined. By heating the catalyst at a constant rate from 150-300 ℃, temper-ature fluctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show thatODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from thecatalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of thecatalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3catalyst. The intrinsic Arrhenius rate constant for the ODH of isobutane isk(s-1) = 1011.5±2.2exp{-((55 ± 5) - △Hads kJmol-1)/RT}The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with asmall surface area and limited porosity.

  11. Studies on ethylbenzene dehydrogenation with CO2 as soft oxidant over Co3O4/COK-12 catalysts

    Indian Academy of Sciences (India)

    Ramudu Pochamoni; Anand Narani; Mohan Varkolu; Murali Dhar Gudimella; S Sai Prasad Potharaju; David Raju Burri; Seetha Rama Rao Kamaraju

    2015-04-01

    Oxidative dehydrogenation of ethylbenzene to styrene has been studied over Co3O4 supported on mesoporous silica (COK-12) with CO2 as soft oxidant in a fixed bed reactor at atmospheric pressure in the temperature range of 723 to 923K. While COK-12 has been prepared by self-assembly method using long chain ionic surfactant i.e., P123 as template, cobalt oxide supported on COK-12 catalysts with variable Co content have been synthesised by simple wet impregnation technique. All the catalysts were characterized by N2 adsorption - desorption, XRD, FT-IR, TPR, UV-Vis and XPS techniques. XRD and pore size distribution studies indicate the intactness of mesoporous structure of SiO2 even after incorporation of Co3O4. Presence of Co3O4 crystallites were observed beyond 5 wt% Co loading. High ethylbenzene conversion and stable styrene yields have been observed over 3% Co3O4/COK-12 catalyst due to the presence of large number of active Co3O4 catalytic sites. Enhancement in the activity has been observed with CO2 as soft oxidant than with N2 as diluent. This is because of the fact that the liberated H2 reacts with CO2 in the form of reverse water gas shift reaction.

  12. Effects of CeO2 Support Facets on VOx/CeO2 Catalysts in Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Peden, Charles HF; Wang, Yong

    2014-05-13

    CeO2 supports with dominating facets, i.e., low index (100), (110) and (111) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (100) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (100) facets show better dispersion, followed by (110) and (111) facets. The VOx species on CeO2 nanorods with (110) and (100) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (111) facets and CeO2 nanocubes with dominating (100) facets. The higher activity for VOx/CeO2(110) might be related to the more abundant oxygen vacancies present on the (110) facets, evidenced from Raman spectroscopic measurements.

  13. Propane dehydrogenation catalyzed by ZSM-5 zeolites. A mechanistic study based on the selective energy transfer (SET) theory.

    Science.gov (United States)

    Larsson, Ragnar

    2015-02-02

    Experimentally determined activation energies of propane dehydrogenation catalyzed by ZSM-5 zeolites have been used to test the SET theory. The basis of this theory is that the catalyst system transfers vibrational energy via a resonance process to a specific vibration mode of the reacting molecule. Being excited up to a certain number of vibrational quanta the molecule is brought to reaction. By analyzing the above-mentioned activation energies we found the wave number of this "specific mode" to be 1065 cm-1. This is very close to the rocking vibration of propane (1053 cm-1). We suggest that the propane molecule reacts when excited so that the CH3 group has been forced towards a flat structure with a carbon atom hybridization that is more sp2 than sp3. Consequently there is no way for three H-atoms to bind to the carbon and one of them must leave. This is the starting point of the reaction. The isokinetic temperature of the system was found as Tiso = 727 ± 4 K. From the SET formula for Tiso when both energy-donating (ω) and energy-accepting (ν) vibrations have the same frequency, viz., Tiso = Nhcν/2R, we obtain ν = ω = 1011 ± 6 cm-1. This agrees rather well with the CH3 rocking mode (1053 cm-1) and also with asymmetric "TO4" stretching vibrations of the zeolite structure (ω).

  14. Ruthenium nanoparticles confined in SBA-15 as highly efficient catalyst for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

    Science.gov (United States)

    Yao, Qilu; Lu, Zhang-Hui; Yang, Kangkang; Chen, Xiangshu; Zhu, Meihua

    2015-10-01

    Ultrafine ruthenium nanoparticles (NPs) within the mesopores of the SBA-15 have been successfully prepared by using a “double solvents” method, in which n-hexane is used as a hydrophobic solvent and RuCl3 aqueous solution is used as a hydrophilic solvent. After the impregnation and reduction processes, the samples were characterized by XRD, TEM, EDX, XPS, N2 adsorption-desorption, and ICP techniques. The TEM images show that small sized Ru NPs with an average size of 3.0 ± 0.8 nm are uniformly dispersed in the mesopores of SBA-15. The as-synthesized Ru@SBA-15 nanocomposites (NCs) display exceptional catalytic activity for hydrogen generation by the hydrolysis of ammonia borane (NH3BH3, AB) and hydrazine borane (N2H4BH3, HB) at room temperature with the turnover frequency (TOF) value of 316 and 706 mol H2 (mol Ru min)-1, respectively, relatively high values reported so far for the same reaction. The activation energies (Ea) for the hydrolysis of AB and HB catalyzed by Ru@SBA-15 NCs are measured to be 34.8 ± 2 and 41.3 ± 2 kJ mol-1, respectively. Moreover, Ru@SBA-15 NCs also show satisfied durable stability for the hydrolytic dehydrogenation of AB and HB, respectively.

  15. Effect of aluminum modification on catalytic properties of PtSn-based catalysts supported on SBA-15 for propane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Yongzheng Duan; Yuming Zhou; Yiwei Zhang; Xiaoli Sheng; Shijian Zhou; Zewu Zhang

    2012-01-01

    The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15,such as Al-incorporated SBA-15 (AlSBA-15) and alumina-modified SBA-15 (Al2O3/SBA-15),for propane dehydrogenation were investigated.Al2O3/SBA-15 was prepared either by an impregnation method using aluminum nitrate aqueous solution,or by the treatment of SBA-15 with a Al(OC3H7)3 solution in anhydrous toluene.N2-physisorption,FT-IR spectroscopy,solid-state 27Al MAS NMR spectroscopy,hydrogen chemisorption,XRF,NH3 temperature-programmed desorption,X-ray photoelectron spectroscopy and TPO were used to characterize these samples.Among these catalysts,the PtSn-based catalyst supported on Al2O3/SBA-15,which was grafted with Al(OC3H7)3,exhibited the best catalytic performance in terms of activity and stability The possible reason was due to the high Pt metal dispersion and/or the strong interactions among Pt,Sn,and the support.

  16. Optimized synthesis of L-sorbose by C(5)-dehydrogenation of D-sorbitol with Gluconobacter oxydans.

    Science.gov (United States)

    De Wulf, P; Soetaert, W; Vandamme, E J

    2000-08-01

    The optimization of L-sorbose synthesis by regiospecific dehydrogenation of D-sorbitol using Gluconobacter oxydans is reported. The current L-sorbose production processes that are based on G. oxydans and other bacterial strains are suboptimal as to yield and rate of L-sorbose synthesis. One reason for these problems is the toxicity that is induced by the substrate D-sorbitol when used in concentrations of >10% (w/v). This phenomenon significantly limits the potentials of L-sorbose production from an industrial point of view. The goal of this study was to develop a fast production process that yields L-sorbose in stoichiometric amounts starting from D-sorbitol concentrations that exceed 10% (w/v). A gradual improvement of the inoculum build-up procedure, culture medium composition, and process parameters ultimately led to a theoretically maximal L-sorbose productivity (200 g L(-1) of L-sorbose from 200 g L(-1) of D-sorbitol in 28 h of fermentation) using a Gluconobacter oxydans mutant strain that was selected under conditions of substrate inhibition. Because the D-sorbitol/L&HYPHEN;sorbose bioconversion is used to mass-produce vitamin C, the procedure reported here will contribute to a more efficient and more economic synthesis of vitamin C.

  17. Propane Dehydrogenation Catalyzed by ZSM-5 Zeolites. A Mechanistic Study Based on the Selective Energy Transfer (SET Theory

    Directory of Open Access Journals (Sweden)

    Ragnar Larsson

    2015-02-01

    Full Text Available Experimentally determined activation energies of propane dehydrogenation catalyzed by ZSM-5 zeolites have been used to test the SET theory. The basis of this theory is that the catalyst system transfers vibrational energy via a resonance process to a specific vibration mode of the reacting molecule. Being excited up to a certain number of vibrational quanta the molecule is brought to reaction. By analyzing the above-mentioned activation energies we found the wave number of this “specific mode” to be 1065 cm−1. This is very close to the rocking vibration of propane (1053 cm−1. We suggest that the propane molecule reacts when excited so that the CH3 group has been forced towards a flat structure with a carbon atom hybridization that is more sp2 than sp3. Consequently there is no way for three H-atoms to bind to the carbon and one of them must leave. This is the starting point of the reaction. The isokinetic temperature of the system was found as Tiso = 727 ± 4 K. From the SET formula for Tiso when both energy-donating (ω and energy-accepting (ν vibrations have the same frequency, viz., Tiso = Nhcν/2R, we obtain ν = ω = 1011 ± 6 cm−1. This agrees rather well with the CH3 rocking mode (1053 cm−1 and also with asymmetric “TO4” stretching vibrations of the zeolite structure (ω.

  18. Kinetic study of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst

    Institute of Scientific and Technical Information of China (English)

    Farnaz; Tahriri; Zangeneh; Abbas; Taeb; Khodayar; Gholivand; Saeed; Sahebdelfar

    2013-01-01

    The kinetics of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst were studied.Performance test runs were carried out in a fixed-bed integral reactor.Using a power-law rate expression for the surface reaction kinetics and independent law for deactivation kinetics,the experimental data were analyzed both by integral and a novel differential method of analysis and the results were compared.To avoid fluctuation of time-derivatives of conversion required for differential analysis,the conversion-time data were first fitted with appropriate functions.While the time-zero and rate constant of reaction were largely insensitive to the function employed,the rate constant of deactivation was much more sensitive to the function form.The advantage of the proposed differential method,however,is that the integration of the rate expression is not necessary which otherwise could be complicated or impossible.It was also found that the reaction is not limited by external and internal mass transfer limitations,implying that the employed kinetics could be considered as intrinsic ones.

  19. Photocatalytic Ethanol Oxidative Dehydrogenation over Pt/TiO2: Effect of the Addition of Blue Phosphors

    Directory of Open Access Journals (Sweden)

    J. J. Murcia

    2012-01-01

    Full Text Available Ethanol oxidative dehydrogenation over Pt/TiO2 photocatalyst, in the presence and absence of blue phosphors, was performed. The catalyst was prepared by photodeposition of Pt on sulphated TiO2. This material was tested in a gas-solid photocatalytic fluidized bed reactor at high illumination efficiency. The effect of the addition of blue phosphors into the fluidized bed has been evaluated. The synthesized catalysts were extensively characterized by different techniques. Pt/TiO2 with a loading of 0.5 wt% of Pt appeared to be an active photocatalyst in the selective partial oxidation of ethanol to acetaldehyde improving its activity and selectivity compared to pure TiO2. In the same way, a notable enhancement of ethanol conversion in the presence of the blue phosphors has been obtained. The blue phosphors produced an increase in the level of ethanol conversion over the Pt/TiO2 catalyst, keeping at the same time the high selectivity to acetaldehyde.

  20. Improvement in dehydrogenation of MXH4 where M = Na, Li and X = Al, B confined in CNTs: a DFT investigation

    Science.gov (United States)

    Meenakshi; Agnihotri, Deepak; Jeet, Kiran; Sharma, Hitesh

    2016-11-01

    Nanoconfinement improves dehydrogenation kinetics of complex metal hydrides. The present paper reports effect of confinement of MXH4, where M = Na, Li and X = Al, B inside carbon nanotubes (CNTs) (n, 0) n = 9-11 chirality and diameter of 7.47 Å, 7.87 Å, 8.73 Å, respectively, using Density Functional calculations. The MXH4 interacts strongly with the surface atoms of CNT (11, 0) and is found to be the smallest stable system for confinement of MXH4 clusters. The Hydrogen release energy (E Hre) of NaAlH4 decreases sharply by 68.3 % , w.r.t. pure NaAlH4 cluster when confined inside CNT(11, 0). Similarly, in CNT (11, 0) E Hre decreases by 38.1 % for LiAlH4, 12.7 % for NaBH4 and 19.1 % for LiBH4. Thus, resulting confinement had a profound effect in improving the energetics of complex metal hydride nanoparticles without catalyst.

  1. Thermochemical Energy Storage through De/Hydrogenation of Organic Liquids: Reactions of Organic Liquids on Metal Hydrides.

    Science.gov (United States)

    Ulmer, Ulrich; Cholewa, Martin; Diemant, Thomas; Bonatto Minella, Christian; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

    2016-06-08

    A study of the reactions of liquid acetone and toluene on transition metal hydrides, which can be used in thermal energy or hydrogen storage applications, is presented. Hydrogen is confined in TiFe, Ti0.95Zr0.05Mn1.49V0.45Fe0.06 ("Hydralloy C5"), and V40Fe8Ti26Cr26 after contact with acetone. Toluene passivates V40Fe8Ti26Cr26 completely for hydrogen desorption while TiFe is only mildly deactivated and desorption is not blocked at all in the case of Hydralloy C5. LaNi5 is inert toward both organic liquids. Gas chromatography (GC) investigations reveal that CO, propane, and propene are formed during hydrogen desorption from V40Fe8Ti26Cr26 in liquid acetone, and methylcyclohexane is formed in the case of liquid toluene. These reactions do not occur if dehydrogenated samples are used, which indicates an enhanced surface reactivity during hydrogen desorption. Significant amounts of carbon-containing species are detected at the surface and subsurface of acetone- and toluene-treated V40Fe8Ti26Cr26 by X-ray photoelectron spectroscopy (XPS). The modification of the surface and subsurface chemistry and the resulting blocking of catalytic sites is believed to be responsible for the containment of hydrogen in the bulk. The surface passivation reactions occur only during hydrogen desorption of the samples.

  2. Iodine-deficiency disorders

    NARCIS (Netherlands)

    Zimmermann, M.B.; Jooste, P.L.; Pandav, C.S.

    2008-01-01

    billion individuals worldwide have insufficient iodine intake, with those in south Asia and sub-Saharan Africa particularly affected. Iodine deficiency has many adverse effects on growth and development. These effects are due to inadequate production of thyroid hormone and are termed iodine-deficien

  3. Factor V deficiency

    Science.gov (United States)

    ... When certain blood clotting factors are low or missing, your blood does not clot properly. Factor V deficiency is rare. It may be caused by: A defective Factor V gene passed down through families (inherited) An antibody that interferes with normal Factor ...

  4. Alpha1-antitrypsin deficiency

    DEFF Research Database (Denmark)

    Stolk, Jan; Seersholm, Niels; Kalsheker, Noor

    2006-01-01

    biennially to exchange views and research findings. The fourth biennial meeting was held in Copenhagen, Denmark, on 2-3 June 2005. This review covers the wide range of AAT deficiency-related topics that were addressed encompassing advances in genetic characterization, risk factor identification, clinical...... epidemiology, inflammatory and signalling processes, therapeutic advances, and lung imaging techniques....

  5. MCAD deficiency in Denmark

    DEFF Research Database (Denmark)

    Andresen, Brage Storstein; Lund, Allan Meldgaard; Hougaard, David Michael

    2012-01-01

    Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most common defect of fatty acid oxidation. Many countries have introduced newborn screening for MCADD, because characteristic acylcarnitines can easily be identified in filter paper blood spot samples by tandem mass spectrometry (MS...

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... blood transfusions , iron injections, or intravenous iron therapy. Rate This Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the National Heart, Lung, and Blood Institute, part of the National ...

  7. Iodine-deficiency disorders

    NARCIS (Netherlands)

    Zimmermann, M.B.; Jooste, P.L.; Pandav, C.S.

    2008-01-01

    billion individuals worldwide have insufficient iodine intake, with those in south Asia and sub-Saharan Africa particularly affected. Iodine deficiency has many adverse effects on growth and development. These effects are due to inadequate production of thyroid hormone and are termed iodine-deficien

  8. Vitamin B12 deficiency

    Science.gov (United States)

    Vitamin B12 (B12; also known as cobalamin) is a B vitamin that has an important role in cellular metabolism, especially in DNA synthesis, methylation and mitochondrial metabolism. Clinical B12 deficiency with classic haematological and neurological manifestations is relatively uncommon. However, sub...

  9. Morbidity and GH deficiency

    DEFF Research Database (Denmark)

    Stochholm, Kirstine; Laursen, Torben; Green, Anders;

    2008-01-01

    OBJECTIVE: To estimate morbidity in Denmark in all patients with GH deficiency (GHD). DESIGN: Morbidity was analyzed in 1794 GHD patients and 8014 controls matched on age and gender. All records in the GHD patients were studied and additional morbidity noted. Diagnoses and dates of admissions were...

  10. Diagnosing oceanic nutrient deficiency

    Science.gov (United States)

    Moore, C. Mark

    2016-11-01

    The supply of a range of nutrient elements to surface waters is an important driver of oceanic production and the subsequent linked cycling of the nutrients and carbon. Relative deficiencies of different nutrients with respect to biological requirements, within both surface and internal water masses, can be both a key indicator and driver of the potential for these nutrients to become limiting for the production of new organic material in the upper ocean. The availability of high-quality, full-depth and global-scale datasets on the concentrations of a wide range of both macro- and micro-nutrients produced through the international GEOTRACES programme provides the potential for estimation of multi-element deficiencies at unprecedented scales. Resultant coherent large-scale patterns in diagnosed deficiency can be linked to the interacting physical-chemical-biological processes which drive upper ocean nutrient biogeochemistry. Calculations of ranked deficiencies across multiple elements further highlight important remaining uncertainties in the stoichiometric plasticity of nutrient ratios within oceanic microbial systems and caveats with regards to linkages to upper ocean nutrient limitation. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  11. Manganese deficiency in plants

    DEFF Research Database (Denmark)

    Schmidt, Sidsel Birkelund; Jensen, Poul Erik; Husted, Søren

    2016-01-01

    Manganese (Mn) is an essential plant micronutrient with an indispensable function as a catalyst in the oxygen-evolving complex (OEC) of photosystem II (PSII). Even so, Mn deficiency frequently occurs without visual leaf symptoms, thereby masking the distribution and dimension of the problem...

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... blood transfusions , iron injections, or intravenous iron therapy. Rate This Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the National Heart, Lung, and Blood Institute, part of the National ...

  13. Application of De-hydrogen Technology of High Pressure Carbon Dioxide in Urea Plant%高压二氧化碳脱氢技术在尿素装置的应用

    Institute of Scientific and Technical Information of China (English)

    左玉静; 张丛志

    2013-01-01

    In order to increase the safety of urea plant, the de-hydrogen device was arranged in the urea plant with CO2 stripping method with a ca-pacity of 400,000 t/a of Shandong Hualu Hengsheng Chemical Engineering Stock Company Ltd., before the raw gas of CO2 entered into high pressure system of urea.Author has introduced the working principle and the physical and chemical properties for de-hydrogen catalyst; has briefly described the process flow of the de-hydrogen device; has summarized the running situation of the de-hydrogen device; has presented the related matters to be noticed in case of applying of CO2 de-hydrogen technology.%山东华鲁恒升化工股份有限公司40万t/a CO2气提法尿素装置在原料气CO2进入尿素高压系统前设置了脱氢装置,以提高尿素装置的安全性。介绍了脱氢催化剂的工作原理和物化性能;简述了脱氢装置的工艺流程;总结了脱氢装置的运行情况;提出了应用CO2脱氢技术时应注意的相关事项。

  14. Genetics Home Reference: carbonic anhydrase VA deficiency

    Science.gov (United States)

    ... hyperammonemia due to carbonic anhydrase VA deficiency hyperammonemic encephalopathy due to carbonic anhydrase VA deficiency mitochondrial carbonic anhydrase va deficiency Related Information How are ...

  15. Glucose-6-phosphate dehydrogenase deficiency

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000528.htm Glucose-6-phosphate dehydrogenase deficiency To use the sharing features on this page, please enable JavaScript. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a condition in which ...

  16. Cobalamin deficiency, hyperhomocysteinemia, and dementia

    National Research Council Canada - National Science Library

    Werder, Steven F

    2010-01-01

    ...) What is to be expected from treatment? (7) How is B12 deficiency treated? On January 31st, 2009, a Medline search was performed revealing 1,627 citations related to cobalamin deficiency, hyperhomocysteinemia, and dementia...

  17. Growth Hormone Deficiency in Children

    Science.gov (United States)

    Fact Sheet Growth Defici H e o n r c m y one in Children What is growth hormone deficiency? Growth hormone deficiency (GHD) is a rare condition in which the body does not make enough growth hormone (GH). GH is made by the pituitary ...

  18. Iron deficiency and cognitive functions

    Directory of Open Access Journals (Sweden)

    Jáuregui-Lobera I

    2014-11-01

    Full Text Available Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with emotions and behavior, often directly related to the presence of iron deficiency anemia. In addition, iron deficiency without anemia may cause cognitive disturbances. At present, the prevalence of iron deficiency and iron deficiency anemia is 2%–6% among European children. Given the importance of iron deficiency relative to proper cognitive development and the alterations that can persist through adulthood as a result of this deficiency, the objective of this study was to review the current state of knowledge about this health problem. The relevance of iron deficiency and iron deficiency anemia, the distinction between the cognitive consequences of iron deficiency and those affecting specifically cognitive development, and the debate about the utility of iron supplements are the most relevant and controversial topics. Despite there being methodological differences among studies, there is some evidence that iron supplementation improves cognitive functions. Nevertheless, this must be confirmed by means of adequate follow-up studies among different groups. Keywords: iron deficiency, anemia, cognitive functions, supplementation

  19. [Selective immunoglobulin A deficiency].

    Science.gov (United States)

    Binek, Alicja; Jarosz-Chobot, Przemysława

    2012-01-01

    Immunoglobulin class A is the main protein of the mucosal immune system. Selective immunoglobulin A deficiency (sIgAD) is the most common primary immunodeficiency in Caucasians. sIGAD is strongly associated with the certain major histocompatibility complex region. Most individuals with sIgAD are asymptomatic and identified coincidentally. However, some patients may present with recurrent infections, allergic disorders and autoimmune manifestations. Several autoimmune diseases, such as systemic lupus erythematosus, diabetes mellitus type 1, Graves disease and celiac disease, are associated with an increased prevalence of sIgAD. Screening for sIgAD in coeliac disease is essential. Patients need treatment of associated diseases. It is also known that IgA deficiency may progress into a common variable immunodeficiency (CVID). Pathogenesis and molecular mechanism involved in sIgAD should be elucidated in the future.

  20. Isolated sulfite oxidase deficiency.

    Science.gov (United States)

    Relinque, B; Bardallo, L; Granero, M; Jiménez, P J; Luna, S

    2015-03-10

    Sulfite oxidase deficiency is an uncommon metabolic disease. Only few cases of its isolated form have been reported in the literature. We report a case of severe neonatal onset. A newborn baby of 41 weeks gestational age, weighted at birth of 3240 grams and had an Apgar score of 6-10-10. Fifty-three hours after being born, the baby started with seizures that were refractory to antiepileptic treatment. Brain function was monitored using a-EEG. Laboratory and imaging tests were performed. All of them were consistent with sulfite oxidase deficiency. The diagnosis was confirmed by genetic testing. We highlight the importance of this disease as part of the differential diagnosis of seizures during the neonatal period, as well as the importance of the therapeutic support based on dietary restrictions. It's also remarkable the possibility of prenatal diagnosis by quantifying enzyme activity and it's also possible carrying out DNA mutational analysis.

  1. Proximal Focal Femoral Deficiency

    Directory of Open Access Journals (Sweden)

    Vishal Kalia, Vibhuti

    2008-01-01

    Full Text Available Proximal focal femoral deficiency (PFFD is a developmental disorder of the proximal segment of thefemur and of acetabulum resulting in shortening of the affected limb and impairment of the function. It isa spectrum of congenital osseous anomalies characterized by a deficiency in the structure of the proximalfemur. The diagnosis is often made by radiological evaluation which includes identification and descriptionof PFFD and evaluation of associated limb anomalies by plain radiographs. Contrast arthrography orMagnetic Resonance Imaging is indicated when radiological features are questionable and to disclose thepresence and location of the femoral head and any cartilagenous anlage. The disorder is more commonlyunilateral and is apparent at birth. However, bilateral involvement is rarely seen. Therapy of the disorder isdirected towards satisfactory ambulation and specific treatment depending on the severity of dysplasia.

  2. Methanol Oxidative Dehydrogenation on Oxide Catalysts: Molecular and Dissociative Routes and Hydrogen Addition Energies as Descriptors of Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Deshlahra, Prashant; Iglesia, Enrique

    2014-11-13

    The oxidative dehydrogenation (ODH) of alkanols on oxide catalysts is generally described as involving H-abstraction from alkoxy species formed via O–H dissociation. Kinetic and isotopic data cannot discern between such routes and those involving kinetically-relevant H-abstraction from undissociated alkanols. Here, we combine such experiments with theoretical estimates of activation energies and entropies to show that the latter molecular routes prevail over dissociative routes for methanol reactions on polyoxometalate (POM) clusters at all practical reaction temperatures. The stability of the late transition states that mediate H-abstraction depend predominantly on the stability of the O–H bond formed, making H-addition energies (HAE) accurate and single-valued descriptors of reactivity. Density functional theory-derived activation energies depend linearly on HAE values at each O-atom location on clusters with a range of composition (H3PMo12, H4SiMo12, H3PW12, H4PV1Mo11, and H4PV1W11); both barriers and HAE values reflect the lowest unoccupied molecular orbital energy of metal centers that accept the electron and the protonation energy of O-atoms that accept the proton involved in the H-atom transfer. Bridging O-atoms form O–H bonds that are stronger than those of terminal atoms and therefore exhibit more negative HAE values and higher ODH reactivity on all POM clusters. For each cluster composition, ODH turnover rates reflect the reactivity-averaged HAE of all accessible O-atoms, which can be evaluated for each cluster composition to provide a rigorous and accurate predictor of ODH reactivity for catalysts with known structure. These relations together with oxidation reactivity measurements can then be used to estimate HAE values and to infer plausible structures for catalysts with uncertain active site structures.

  3. Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101:Insight into chromium species on activity and selectivity

    Institute of Scientific and Technical Information of China (English)

    Huahua Zhao; Huanling Song; Zhichao Miao; Lingjun Chou

    2014-01-01

    Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCrAl-I1 with largest specific surface area of 198 m2·g−1 prepared with aluminium isopropoxide (Al(i-OC3H7)3) by ultrasonic im-pregnation method. However, the catalyst KCrAl-I2 synthesized by stirring impregnation possessed crystallineα-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich CrxAl2−xO3 solid solutions, designated as CrAl-I and CrAl-II phase, were formed over the catalysts KCrAl-I3 (prepared by Al(i-OC3H7)3 with nitric acid regulation), KCrAl-C4 (prepared by aluminium chloride hexahydrate) and KCrAl-N5 (prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCrAl-I1 exhibited the high isobutane con-version due to its highly dispersed chromium species. However, KCrAl-I3, KCrAl-C4 and KCrAl-N5 showed the higher isobutene selectivity (95.2%−96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.

  4. Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

    Directory of Open Access Journals (Sweden)

    A.M. Elfadly

    2013-12-01

    Full Text Available Nano alumina-supported V2O5 catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO2 as an oxidant. High surface area nano-alumina was prepared and used as support for V2O5 as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW, respectively. The V2O5 loading was varied on nano-alumina from 5 to 30 wt%. The support and catalysts were characterized by X-ray diffraction (XRD, Barett–Joyner–Halenda (BJH pore-size distribution, N2-adsorption isotherms, Fourier transform infrared (FT-IR, scanning electron microscopy (SEM, transmission electron microscopy (TEM and temperature programed desorption (TPD-NH3. The characterization results indicated that V2O5 is highly dispersed on alumina up to 30%-V2O5/γ-Al2O3-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600 °C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (∼100% toward styrene production were obtained using 10% V2O5/γ-Al2O3-MW catalyst treated with microwave.

  5. Rare earth oxides doped NiO/γ-Al2O3 catalyst for oxidative dehydrogenation of cyclohexane

    Institute of Scientific and Technical Information of China (English)

    Hany M AbdelDayem; M Faiz; Hesham S Abdel-Samad; Salah A Hassan

    2015-01-01

    The effect of rare earth oxides (RE=Ce, La, Gd, and Dy) doping of alumina support in NiO/γ-Al2O3 system was investi-gated on its catalytic performance in oxidative dehydrogenation (ODH) of cyclohexane. The physicochemical properties of various samples were followed up through N2 physisorption, temperature programmed reduction (H2-TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and potentiometric acid-base titration techniques. In the parent NiO/γ-Al2O3 catalyst, Ni species were found to be strongly interacted with alumina surface. Addition of rare earth dopants toγ-Al2O3 in the catalyst system affected the nickel-alumina interaction and resulted in significant modifications in the catalytic performances in the ODH reaction. The results re-vealed the beneficial role of both La2O3 and Gd2O3 doping in enhancing the ODH catalytic activity and selectivity to cyclohexene. H2-TPR and XPS results indicated that majority of Ni species in NiO/La2O3 modifiedγ-Al2O3 were more weakly interacted with La2O3 and alumina whereas both NiO like species and nickel aluminate were present on the surface. Doping with cerium or dyspro-sium increased the nickel-support interaction and led to a decrease in surface nickel concentration. In case of doping with Ce, surface concentration of cerium oxide was higher than those of the other RE oxides; the doped catalyst reached its steady state activity faster than the other catalysts. The acid-base results suggested that RE metals were interacted most likely with acidic surface hydroxyl groups. The degree of nickel-alumina interaction decreased in the following order: LaAl>GdAl>CeAl>DyAl.

  6. Significantly improved dehydrogenation of ball-milled MgH2 doped with CoFe2O4 nanoparticles

    Science.gov (United States)

    Shan, Jiawei; Li, Ping; Wan, Qi; Zhai, Fuqiang; Zhang, Jun; Li, Ziliang; Liu, Zhaojiang; Volinsky, Alex A.; Qu, Xuanhui

    2014-12-01

    CoFe2O4 nanoparticles are added to magnesium hydride (MgH2) by high-energy ball milling in order to improve its hydriding properties. The hydrogen storage properties and catalytic mechanism are investigated by pressure-composition-temperature (PCT), differential thermal analysis (DTA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nonisothermal desorption results show that the onset desorption temperature of the MgH2 + 7 mol% CoFe2O4 is 160 °C, which is 200 °C lower than of the as-received MgH2. The dehydrogenation process of the MgH2 doped with the CoFe2O4 nanoparticles includes two steps. DTA curves and XRD patterns reveal that a chemical reaction happens between MgH2 and CoFe2O4, forming the final products of the ternary combination, corresponding to Co3Fe7, MgO and Co. The onset desorption temperature of the ball-milled MgH2 doped with Co3Fe7, MgO and Co is about 260 °C, approximately 100 °C lower than the un-doped MgH2, demonstrating that the ternary combination (Co3Fe7, MgO, and Co) also has a great catalytic effect on the MgH2 hydrogen storage properties. It is also confirmed that the various methods of adding the ternary combination have different effects on the MgH2 hydriding-dehydriding process.

  7. Micronutrient deficiency in children.

    Science.gov (United States)

    Bhan, M K; Sommerfelt, H; Strand, T

    2001-05-01

    Malnutrition increases morbidity and mortality and affects physical growth and development, some of these effects resulting from specific micronutrient deficiencies. While public health efforts must be targeted to improve dietary intakes in children through breast feeding and appropriate complementary feeding, there is a need for additional measures to increase the intake of certain micronutrients. Food-based approaches are regarded as the long-term strategy for improving nutrition, but for certain micronutrients, supplementation, be it to the general population or to high risk groups or as an adjunct to treatment must also be considered. Our understanding of the prevalence and consequences of iron, vitamin A and iodine deficiency in children and pregnant women has advanced considerably while there is still a need to generate more knowledge pertaining to many other micronutrients, including zinc, selenium and many of the B-vitamins. For iron and vitamin A, the challenge is to improve the delivery to target populations. For disease prevention and growth promotion, the need to deliver safe but effective amounts of micronutrients such as zinc to children and women of fertile age can be determined only after data on deficiency prevalence becomes available and the studies on mortality reduction following supplementation are completed. Individual or multiple micronutrients must be used as an adjunct to treatment of common infectious diseases and malnutrition only if the gains are substantial and the safety window sufficiently wide. The available data for zinc are promising with regard to the prevention of diarrhea and pneumonia. It should be emphasized that there must be no displacement of important treatment such as ORS in acute diarrhea by adjunct therapy such as zinc. Credible policy making requires description of not only the clinical effects but also the underlying biological mechanisms. As findings of experimental studies are not always feasible to extrapolate to

  8. Orexin deficiency and narcolepsy

    OpenAIRE

    Sakurai, Takeshi

    2013-01-01

    Orexin deficiency results in the sleep disorder narcolepsy in many mammalian species, including mice, dogs, and humans, suggesting that the orexin system is particularly important for normal regulation of sleep/wakefulness states, and especially for maintenance of wakefulness. This review discusses animal models of narcolepsy; the contribution of each orexin receptor subtype to the narcoleptic phenotypes; and the etiology of orexin neuronal death. It also raises the possibility of novel thera...

  9. Mg3(VO4)2-MgO-ZrO2 nano-catalysts for oxidative dehydrogenation of n-butane.

    Science.gov (United States)

    Lee, Jong Kwon; Seo, Hyun; Hong, Ung Gi; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Park, Gle; Chang, Hosik; Song, In Kyu

    2014-11-01

    A series of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts with different vanadium content (X = 3.3, 5.3, 7.0, 10.2, and 13.4) were prepared by a single-step citric acid-derived sol-gel method for use in the oxidative dehydrogenation of n-butane to n-butene and 1,3-butadiene. The effect of vanadium content of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts on their physicochemical properties and catalytic activities in the oxidative dehydrogenation of n-butane was investigated. Successful formation of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts was confirmed by XRD, Raman spectroscopy, and ICP-AES analyses. The catalytic performance of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts strongly depended on vanadium content. All the X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts showed a stable catalytic performance without catalyst deactivation during the reaction. Among the catalysts tested, 7.0-Mg3(VO4)2-MgO-ZrO2 nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butene and 1,3-butadiene). TPRO (temperature-programmed reoxidation) experiments were carried out to measure the oxygen capacity of the catalyst. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic performance. Yield for TDP increased with increasing oxygen capacity of the catalyst.

  10. A liquid-based eutectic system: LiBH4·NH 3-nNH3BH3 with high dehydrogenation capacity at moderate temperature

    KAUST Repository

    Tan, Yingbin

    2011-01-01

    A novel eutectic hydrogen storage system, LiBH4·NH 3-nNH3BH3, which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH 4·NH3 and NH3BH3 (AB). In the temperature range of 90-110 °C, the eutectic system showed significantly improved dehydrogenation properties compared to the neat AB and LiBH 4·NH3 alone. For example, in the case of the LiBH4·NH3/AB with a mole ratio of 1:3, over 8 wt.% hydrogen could be released at 90 °C within 4 h, while only 5 wt.% hydrogen released from the neat AB at the same conditions. Through a series of experiments it has been demonstrated that the hydrogen release of the new system is resulted from an interaction of AB and the NH3 group in the LiBH4·NH3, in which LiBH4 works as a carrier of ammonia and plays a crucial role in promoting the interaction between the NH3 group and AB. The enhanced dehydrogenation of LiBH 4·NH3/AB may result from the polar liquid state reaction environments and the initially promoted formation of the diammoniate of diborane, which will facilitate the B-H⋯H-N interaction between LiBH4·NH3 and AB. Kinetics analysis revealed that the rate-controlling steps of the dehydrogenation process are three-dimensional diffusion of hydrogen at temperatures ranging from 90 to 110 °C. This journal is © The Royal Society of Chemistry.

  11. Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

    KAUST Repository

    Balasamy, Rabindran J.

    2011-05-01

    A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

  12. Genotypic and phenotypic spectrum of pyridoxine-dependent epilepsy (ALDH7A1 deficiency).

    Science.gov (United States)

    Mills, Philippa B; Footitt, Emma J; Mills, Kevin A; Tuschl, Karin; Aylett, Sarah; Varadkar, Sophia; Hemingway, Cheryl; Marlow, Neil; Rennie, Janet; Baxter, Peter; Dulac, Olivier; Nabbout, Rima; Craigen, William J; Schmitt, Bernhard; Feillet, François; Christensen, Ernst; De Lonlay, Pascale; Pike, Mike G; Hughes, M Imelda; Struys, Eduard A; Jakobs, Cornelis; Zuberi, Sameer M; Clayton, Peter T

    2010-07-01

    Pyridoxine-dependent epilepsy was recently shown to be due to mutations in the ALDH7A1 gene, which encodes antiquitin, an enzyme that catalyses the nicotinamide adenine dinucleotide-dependent dehydrogenation of l-alpha-aminoadipic semialdehyde/L-Delta1-piperideine 6-carboxylate. However, whilst this is a highly treatable disorder, there is general uncertainty about when to consider this diagnosis and how to test for it. This study aimed to evaluate the use of measurement of urine L-alpha-aminoadipic semialdehyde/creatinine ratio and mutation analysis of ALDH7A1 (antiquitin) in investigation of patients with suspected or clinically proven pyridoxine-dependent epilepsy and to characterize further the phenotypic spectrum of antiquitin deficiency. Urinary L-alpha-aminoadipic semialdehyde concentration was determined by liquid chromatography tandem mass spectrometry. When this was above the normal range, DNA sequencing of the ALDH7A1 gene was performed. Clinicians were asked to complete questionnaires on clinical, biochemical, magnetic resonance imaging and electroencephalography features of patients. The clinical spectrum of antiquitin deficiency extended from ventriculomegaly detected on foetal ultrasound, through abnormal foetal movements and a multisystem neonatal disorder, to the onset of seizures and autistic features after the first year of life. Our relatively large series suggested that clinical diagnosis of pyridoxine dependent epilepsy can be challenging because: (i) there may be some response to antiepileptic drugs; (ii) in infants with multisystem pathology, the response to pyridoxine may not be instant and obvious; and (iii) structural brain abnormalities may co-exist and be considered sufficient cause of epilepsy, whereas the fits may be a consequence of antiquitin deficiency and are then responsive to pyridoxine. These findings support the use of biochemical and DNA tests for antiquitin deficiency and a clinical trial of pyridoxine in infants and

  13. [Iron deficiency, thrombocytosis and thromboembolism].

    Science.gov (United States)

    Evstatiev, Rayko

    2016-10-01

    Iron deficiency, the most common nutritional deficiency worldwide, is often associated with reactive thrombocytosis. Although secondary thrombocytosis is commonly considered to be harmless, there is accumulating evidence that elevated platelet counts, especially in the setting of iron deficiency, can lead to an increased thromboembolic risk in both arterial and venous systems. Here we present the mechanisms of iron deficiency-induced thrombocytosis and summarize its clinical consequences especially in patients with inflammatory bowel diseases, chronic kidney disease or cancer. We hypothesize that iron deficiency is an underestimated thromboembolic risk factor, and that iron replacement therapy can become an effective preventive strategy in a variety of clinical settings.

  14. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... TV, Video Games, and the Internet Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia Print A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  15. How Is Iron-Deficiency Anemia Treated?

    Science.gov (United States)

    ... the NHLBI on Twitter. How Is Iron-Deficiency Anemia Treated? Treatment for iron-deficiency anemia will depend ... may be advised. Treatments for Severe Iron-Deficiency Anemia Blood Transfusion If your iron-deficiency anemia is ...

  16. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... Your 1- to 2-Year-Old Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia A A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  17. Effect of the plasma-chemical treatment of ZnO and NiO on their activity in the dehydrogenation of isopropanol

    Science.gov (United States)

    Danilova, M. N.; Pylinina, A. I.; Platonov, E. A.; Yagodovskii, V. D.

    2015-08-01

    Treating ZnO and NiO oxides with glow discharge oxygen plasma and high-frequency argon plasma is found to affect the catalytic activity of these oxides in the dehydrogenation reaction of isopropanol, leading to an increase in the conversion of alcohol and the yield of acetone. The increased activity of ZnO is due to the high number of acid sites induced by plasma-chemical treatment. With NiO, the increased activity results from the formation of new, more active sites with low experimental activation energy, rather than a change in the surface acidity.

  18. Generation of decarboxylated and dehydrogenated betacyanins in thermally treated purified fruit extract from purple pitaya (Hylocereus polyrhizus) monitored by LC-MS/MS.

    Science.gov (United States)

    Wybraniec, Sławomir; Mizrahi, Yosef

    2005-08-24

    Pigments of purple pitaya [Hylocereus polyrhizus (F.A.C. Weber) Britton and Rose] fruits were submitted to extraction and were decarboxylated during heating experiments in acidified ethanolic and aqueous solutions. Groups of betacyanins with different decarboxylation levels were identified in the heating products by LC-DAD and LC-MS/MS. The main decarboxylation products were 2-decarboxy-betacyanins, 17-decarboxy-betacyanins, and 2,17-bidecarboxy-betacyanins. The structures of other compounds were assigned to 2,15,17-tridecarboxy-betacyanins and 14,15-dehydrogenated derivatives (neo-derivatives) of all decarboxylated betacyanins found.

  19. Effects of Zeolite Structure and Si/Al Ratio on Adsorption Thermodynamics and Intrinsic Kinetics of Monomolecular Cracking and Dehydrogenation of Alkanes over Bronsted Acid Sites

    Science.gov (United States)

    Janda, Amber Leigh

    It is well known that the efficacy of acidic zeolite catalysts for the cracking of hydrocarbons originates from the shape and size of the zeolite pores. However, the mechanisms by which changes in pore structure influence cracking kinetics are not well understood or exploited. The aim of this dissertation is to use experiments and simulations to shed light on the ways by which zeolite structure and acid site location affect the apparent and intrinsic kinetics of n-alkane monomolecular cracking and dehydrogenation. In the rate-determining step of these processes, C-C or C-H bonds are cleaved catalytically by Bronsted protons. Thus, the kinetics of monomolecular activation reactions are useful for characterizing the influence of active site structural environment on catalysis. In Chapter 2, the effects of active site distribution on n-butane monomolecular activation kinetics are investigated for commercial samples of MFI having a range of the Si/Al ratio. Based on UV-visible spectroscopic analyses of (Co,Na)-MFI, it is inferred that, with increasing Al concentration, the fraction of Co---and, by extension, Bronsted protons in H-MFI---located at channel intersections increases relative to the fraction located at channels. Concurrently, the first-order rate coefficients (kapp) for cracking and dehydrogenation, the selectivity to terminal cracking versus central cracking, and the selectivity to dehydrogenation versus cracking increase. The stronger dependence of the selectivity to dehydrogenation on Al content is attributed to a product-like transition state, the stability of which is more sensitive to confinement than the stabilities of cracking transition states, which occur earlier along the reaction coordinate. For terminal cracking and dehydrogenation, the intrinsic activation entropy (DeltaS‡int ) increases with Al content, consistent with the larger dimensions of intersections relative to channels. Surprisingly, the rate of dehydrogenation is inhibited by

  20. CATALYTIC DEHYDROGENATION OF LONG CHAIN ALKANES IN SUPERCRITICAL PHASE%超临界相中的长链烷烃催化脱氢

    Institute of Scientific and Technical Information of China (English)

    魏伟; 孙予罕; 钟炳

    1999-01-01

    @@ The preparation of olefins from long chain alkanes by catalytic dehydrogenation is an important process in synthetic detergents and surface-active agents[1]. Because of equilibrium limitation, the present process only reaches about 10 % of the conversion with 90 % of the selectivity. In addition, the lifetime of the catalysts ( e. g. Pt-Sn/Al2O3) is around 40 d owing to the severe coke formation even with n(H2 )/n(alkane)= 8. Although the catalysts have been well improved, both conversion and selectivity were hardly enhanced. New technique is therefore required to improve the process.

  1. Palladium(II)-Catalyzed Cross-Dehydrogenative Coupling (CDC) of N-Phthaloyl Dehydroalanine Esters with Simple Arenes: Stereoselective Synthesis of Z-Dehydrophenylalanine Derivatives.

    Science.gov (United States)

    Bartoccini, Francesca; Cannas, Diego Maria; Fini, Francesco; Piersanti, Giovanni

    2016-06-03

    Pd(II)-catalyzed cross-dehydrogenative coupling (CDC) of methyl N-phthaloyl dehydroalanine esters with simple aromatic hydrocarbons is reported. The reaction, which involves the cleavage of two sp(2) C-H bonds followed by C-C bond formation, stereoselectively generates highly valuable Z-dehydrophenylalanine skeletons in a practical, versatile, and atom economical manner. In addition, a perfluorinated product was expediently converted into important nonproteinogenic amino acid building blocks through copper-catalyzed conjugate additions of boron, silicon, and hydride moieties.

  2. Silver-Free Direct Synthesis of Alkynylphosphine Oxides via spC-H/P(O)-H Dehydrogenative Coupling Catalyzed by Palladium.

    Science.gov (United States)

    Zhang, Jian-Qiu; Chen, Tieqiao; Zhang, Ji-Shu; Han, Li-Biao

    2017-09-01

    A silver-free palladium-catalyzed dehydrogenative phosphorylation of terminal alkynes with hydrogen phosphine oxides has been developed. Both aromatic and aliphatic terminal alkynes including those bearing functional groups coupled readily with hydrogen phosphine oxides, producing the corresponding value-added alkynylphosphine oxides in good to excellent yields. This reaction could be easily conducted at gram scales (10 mmol) without any decrease of the reaction efficiency, showing highly potential synthetic value in organic synthesis. A plausible Pd(0)/Pd(II) mechanism is proposed.

  3. Hydroformylation of olefins and reductive carbonylation of aryl halides with syngas formed ex situ from dehydrogenative decarbonylation of hexane-1,6-diol

    DEFF Research Database (Denmark)

    Christensen, Stig Holden; Olsen, Esben Paul Krogh; Rosenbaum, Jascha;

    2014-01-01

    A variety of primary alcohols have been investigated as convenient substrates for the ex situ delivery of carbon monoxide and molecular hydrogen in a two-chamber reactor. The gaseous mixture is liberated in one chamber by an iridium-catalysed dehydrogenative decarbonylation of the alcohol...... and then consumed in the other chamber in either a rhodium-catalysed hydroformylation of olefins or a palladium-catalysed reductive carbonylation of aryl halides. Hexane-1,6-diol was found to be the optimum alcohol for both reactions where moderate to excellent yields were obtained of the product aldehydes...

  4. Phenylalanine hydroxylase deficiency.

    Science.gov (United States)

    Mitchell, John J; Trakadis, Yannis J; Scriver, Charles R

    2011-08-01

    Phenylalanine hydroxylase deficiency is an autosomal recessive disorder that results in intolerance to the dietary intake of the essential amino acid phenylalanine. It occurs in approximately 1:15,000 individuals. Deficiency of this enzyme produces a spectrum of disorders including classic phenylketonuria, mild phenylketonuria, and mild hyperphenylalaninemia. Classic phenylketonuria is caused by a complete or near-complete deficiency of phenylalanine hydroxylase activity and without dietary restriction of phenylalanine most children will develop profound and irreversible intellectual disability. Mild phenylketonuria and mild hyperphenylalaninemia are associated with lower risk of impaired cognitive development in the absence of treatment. Phenylalanine hydroxylase deficiency can be diagnosed by newborn screening based on detection of the presence of hyperphenylalaninemia using the Guthrie microbial inhibition assay or other assays on a blood spot obtained from a heel prick. Since the introduction of newborn screening, the major neurologic consequences of hyperphenylalaninemia have been largely eradicated. Affected individuals can lead normal lives. However, recent data suggest that homeostasis is not fully restored with current therapy. Treated individuals have a higher incidence of neuropsychological problems. The mainstay of treatment for hyperphenylalaninemia involves a low-protein diet and use of a phenylalanine-free medical formula. This treatment must commence as soon as possible after birth and should continue for life. Regular monitoring of plasma phenylalanine and tyrosine concentrations is necessary. Targets of plasma phenylalanine of 120-360 μmol/L (2-6 mg/dL) in the first decade of life are essential for optimal outcome. Phenylalanine targets in adolescence and adulthood are less clear. A significant proportion of patients with phenylketonuria may benefit from adjuvant therapy with 6R-tetrahydrobiopterin stereoisomer. Special consideration must be

  5. Discussion pressure swing adsorption technology of Butane dehydrogenation tail gas extracting hydrogen%从丁烷脱氢尾气提取氢气的变压吸附方法讨论

    Institute of Scientific and Technical Information of China (English)

    屈玉玺; 迟建光

    2015-01-01

    丁烷脱氢尾气提取氢气变压吸附技术是一种新型的气体分离技术,本文探讨从丁烷脱氢尾气提取氢气的变压吸附方法。%Butane dehydrogenation tail gas extracting hydrogen pressure swing adsorption technology is a new type of gas separation technology, this paper discusses the pressure swing adsorption method of extracting hydrogen from butane dehydrogenation tail gas.

  6. Dehydrogenation kinetics of air-exposed MgH2/Mg2Cu and MgH2/MgCu2 studied with in situ X-ray powder diffraction

    DEFF Research Database (Denmark)

    Andreasen, A.; Sørensen, M.B.; Burkarl, R.

    2006-01-01

    The dehydrogenation kinetics of air exposed samples of MgH2/Mg2Cu and MgH2/MgCu2 have been studied with in situ time resolved X-ray powder diffraction. The X-ray setup enabled the recording of full diffraction patterns within 150 s, thereby allowing the study of structural changes combined...... sample was found to be 108 kJ/mol and 160 kJ/mol, respectively. Furthermore, substantially improved dehydrogenation kinetics of MgH2 and resistance towards oxidation of Mg due to the presence of Mg2Cu/MgCu2 are discussed in relation to previous work....

  7. Catalytic Dehydrogenation over Pd-Supported ZSM-5 Zeolite for o-Phenylphenol Synthesis%载钯ZSM-5分子筛催化脱氢合成邻苯基苯酚

    Institute of Scientific and Technical Information of China (English)

    蔡春; 吕春绪

    2001-01-01

    Pd-supported ZSM-5 zeolites prepared through ion exchange technique were used as a dehydrogenation catalyst for synthesis of o-phenylphenol from cyclohexanone. When Si/A1 ratio in the catalyst was 85: 1 or more, an obvious reduction in attenuation rate of catalyst activity was observed.When the Si/Al ratio was of 17 . 1 or less, polymer compounds could be formed on the surface of zeolite, that would decrease the dehydrogenation activity due to the reduction of the specific surface area of the catalyst.

  8. Iatrogenic nutritional deficiencies.

    Science.gov (United States)

    Young, R C; Blass, J P

    1982-01-01

    This article catalogs the nutritional deficiencies inadvertently introduced by certain treatment regimens. Specifically, the iatrogenic effects on nutrition of surgery, hemodialysis, irradiation, and drugs are reviewed. Nutritional problems are particularly frequent consequences of surgery on the gastrointestinal tract. Gastric surgery can lead to deficiencies of vitamin B12, folate, iron, and thiamine, as well as to metabolic bone disease. The benefits of small bowel bypass are limited by the potentially severe nutritional consequences of this procedure. Following bypass surgery, patients should be monitored for signs of possible nutritional probems such as weight loss, neuropathy, cardiac arrhythmias, loss of stamina, or changes in mental status. Minimal laboratory tests should include hematologic evaluation, B12, folate, iron, albumin, calcium, phosphorus, alkaline phosphatase, transaminases, sodium, potassium, chloride, and carbon dioxide levels. Roentgenologic examination of the bone should also be obtained. Loss of bone substance is a major consequence of many forms of treatment, and dietary supplementation with calcium is warranted. Patients undergoing hemodialysis have shown carnitine and choline deficiencies, potassium depletion, and hypovitaminosis, as well as osteomalacia. Chronic drug use may alter intake, synthesis, absorption, transport, storage, metabolism, or excretion of nutrients. Patients vary markedly in the metabolic effects of drugs, and recommendations for nutrition must be related to age, sex, reproductive status, and genetic endowment. Moreover, the illness being treated can itself alter nutritional requirements and the effect of the treatment on nutrient status. The changes in nutritional levels induced by use of estrogen-containing oral contraceptives (OCs) are obscure; however, the effects on folate matabolism appear to be of less clinical import than previously suggested. Reduction in pyridoxine and serum vitamin B12 levels has been

  9. Treatment of carnitine deficiency.

    Science.gov (United States)

    Winter, S C

    2003-01-01

    Carnitine deficiency is a secondary complication of many inborn errors of metabolism. Pharmacological treatment with carnitine not only corrects the deficiency, it facilitates removal of accumulating toxic acyl intermediates and the generation of mitochondrial free coenzyme A (CoA). The United States Food and Drug Administration (US FDA) approved the use of carnitine for the treatment of inborn errors of metabolism in 1992. This approval was based on retrospective chart analysis of 90 patients, with 18 in the untreated cohort and 72 in the treated cohort. Efficacy was evaluated on the basis of clinical and biochemical findings. Compelling data included increased excretion of disease-specific acylcarnitine derivatives in a dose-response relationship, decreased levels of metabolites in the blood, and improved clinical status with decreased hospitalization frequency, improved growth and significantly lower mortality rates as compared to historical controls. Complications of carnitine treatment were few, with gastrointestinal disturbances and odour being the most frequent. No laboratory or clinical safety issues were identified. Intravenous carnitine preparations were also approved for treatment of secondary carnitine deficiency. Since only 25% of enteral carnitine is absorbed and gastrointestinal tolerance of high doses is poor, parenteral carnitine treatment is an appealing alternative therapeutic approach. In 7 patients treated long term with high-dose weekly to daily venous boluses of parenteral carnitine through a subcutaneous venous port, benefits included decreased frequency of decompensations, improved growth, improved muscle strength and decreased reliance on medical foods with liberalization of protein intake. Port infections were the most troubling complication. Theoretical concerns continue to be voiced that carnitine might result in fatal arrhythmias in patients with long-chain fat metabolism defects. No published clinical studies substantiate these

  10. Novel Flower-Like Ag-SiO2-MgO-Al2O3 Material: Preparation, Characterization and Catalytic Application in Methanol Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    LI,Jing-Xia; REN,Li-Ping; DAI,Wei-Lin; CAO,Yong; FAN,Kang-Nian

    2008-01-01

    Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag-SiO2-MgO-Al2O3 catalysts prepared by sol-gel method.The optimal preparation mass fractions were determined as 8.3% MgO,16.5% Al2O3 and 20% silver loading.Using this optimum catalyst,excellent activity and selectivity were obtained.The conversion of methanol and the selectivity to formaldehyde both reached 100%,which were much higher than other previously reported silver supported catalysts.Based on combined characterizations,such as X-ray diffraction (XRD),scanning electronic microscopy (SEM),diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis,DRS),nitrogen adsorption at low temperature,temperature programmed desorption of ammonia (NH3-TPD),desorption of CO2 (CO2-TPD),etc.,the correlation of the catalytic performance to the structural properties of the Ag-SiO2-MgO-Al2O3 catalyst was discussed in detail.This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side-products is attributed to its unique flower-like structure with a surface area less than 1 m2/g,and the strong interactions between neutralized support and the nano-sized Ag particles as active centers.

  11. Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR) for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst.

    Science.gov (United States)

    Medrano, José-Antonio; Julián, Ignacio; Herguido, Javier; Menéndez, Miguel

    2013-05-14

    Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR) provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR), where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500-575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol-1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB). The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen), the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors.

  12. Dehydrogenation of propane in the presence of CO{sub 2} over polyacid chromium oxide catalysts modified by Mo, W and Mn

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Davydov, P.E. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    Effective chromium oxide catalysts without additions and with addition of Mo, W and Mn were prepared and tested in long-duration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of metals were found. It was shown that the best combination of acid-base and redox properties necessary for a decrease of aggregation of chromium-oxide particles was observed over the following catalyst: (3.0 wt.%Cr-1.5 wt.% Mn)/SiO{sub 2}. This catalyst worked stably in durable tests (500 h). Mechanism of propane oxidative dehydrogenation was studied using unstationary response method. It was shown that the process mechanism was similar over all studied catalysts but the catalysts were differed by the adsorption capacity of the reaction components: CO{sub 2} was tied more firmly than C{sub 3}H{sub 6} over Cr and Cr-Mn, C{sub 3}H{sub 6} was tied more strongly than CO{sub 2} over Cr-W. The reverse water-gas shift reaction proceeded in more extent over chromium-oxide catalysts without additions. (orig.)

  13. The Effect of Sulphate Doping on Nanosized TiO2 and MoOx/TiO2 Catalysts in Cyclohexane Photooxidative Dehydrogenation

    Directory of Open Access Journals (Sweden)

    P. Ciambelli

    2008-01-01

    Full Text Available The effect of sulphate doping of titania in promoting activity and selectivity of MoOx/TiO2 catalysts for the cyclohexane photooxidative dehydrogenation has been investigated in a gas-solid fluidized bed reactor. Sulphate and/or molybdate-modified titania catalysts were prepared by incipient wet impregnation of nanosized (5–10 nm crystallite size samples. At 60% of titania surface coverage by MoOx, sulphate surface density was obtained up to 19 μmol/m2 without formation of MoO3. The catalysts were characterized by N2 adsorption-desorption at −196∘C, micro-Raman and UV-visible reflectance spectroscopy, thermogravimetric analysis coupled with mass spectroscopy (TG-MS, and mass titration. Unsulphated and sulphated titania are both active in cyclohexane total oxidation, but sulphate doping of titania has a detrimental effect on the reaction rate. On Mo-based catalysts, polymolybdate species enabled sulphated titania to convert cyclohexane to benzene (99% selectivity and cyclohexene, reducing at zero the formation of CO2. Cyclohexane conversion to benzene is almost linearly dependent on sulphate surface density, resulting in enhanced yield to benzene. The enhanced photooxidative dehydrogenation activity and benzene yield by sulphate doping could be attributed to the increase of surface acidity and, as a consequence, of cyclohexane adsorption.

  14. Single-Site VO x Moieties Generated on Silica by Surface Organometallic Chemistry: A Way To Enhance the Catalytic Activity in the Oxidative Dehydrogenation of Propane

    KAUST Repository

    Barman, Samir

    2016-07-26

    We report here an accurate surface organometallic chemistry (SOMC) approach to propane oxidative dehydrogenation (ODH) using a μ2-oxo-bridged, bimetallic [V2O4(acac)2] (1) (acac = acetylacetonate anion) complex as a precursor. The identity and the nuclearity of the product of grafting and of the subsequent oxidative treatment have been systematically studied by means of FT-IR, Raman, solid-state (SS) NMR, UV-vis DRS, EPR and EXAFS spectroscopies. We show that the grafting of 1 on the silica surface under a rigorous SOMC protocol and the subsequent oxidative thermal treatment lead exclusively to well-defined and isolated monovanadate species. The resulting material has been tested for the oxidative dehydrogenation of propane in a moderate temperature range (400-525 °C) and compared with that of silica-supported vanadium catalysts prepared by the standard impregnation technique. The experimental results show that the catalytic activity in propane ODH is strongly upgraded by the degree of isolation of the VOx species that can be achieved by employing the SOMC protocol. © 2016 American Chemical Society.

  15. Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield

    Science.gov (United States)

    Araújo, Paulo Jardel P.; Leite, Manuela Souza; Kakuta Ravagnani, Teresa M.

    2016-01-01

    Styrene is an important monomer in the manufacture of thermoplastic. Most of it is produced by the catalytic dehydrogenation of ethylbenzene. In this process that depends on reversible reactions, the yield is usually limited by the establishment of thermodynamic equilibrium in the reactor. The styrene yield can be increased by using a hybrid process, with reaction and separation simultaneously. It is proposed using permselective composite membrane to remove hydrogen and thus suppress the reverse and secondary reactions. This paper describes the simulation of a dehydrogenation process carried out in a tubular fixed-bed reactor wrapped in a permselective composite membrane. A mathematical model was developed, incorporating the various mass transport mechanisms found in each of the membrane layers and in the catalytic fixed bed. The effects of the reactor feed conditions (temperature, steam-to-oil ratio, and the weight hourly space velocity), the fixed-bed geometry (length, diameter, and volume), and the membrane geometry (thickness of the layers) on the styrene yield were analyzed. These variables were used to determine experimental conditions that favour the production of styrene. The simulation showed that an increase of 40.98% in the styrene yield, compared to a conventional fixed-bed process, could be obtained by wrapping the reactor in a permselective composite membrane. PMID:27069982

  16. Nanoflake-assembled Al2O3-supported CeO2-ZrO2 as an efficient catalyst for oxidative dehydrogenation of ethylbenzene with CO2

    Science.gov (United States)

    Wang, Tehua; Guan, Xiaolin; Lu, Huiyi; Liu, Zhongwen; Ji, Min

    2017-03-01

    An Al2O3 material assembled by nanoflakes was used to prepare supported CeO2-ZrO2 catalyst via a deposition-precipitation method for oxidative dehydrogenation of ethylbenzene with CO2. Both unsupported and commercial Al2O3-supported CeO2-ZrO2 were prepared for comparison. It was found that the CeO2-ZrO2/nanoflake-assembled Al2O3 catalyst exhibited the best catalytic activity. The characterization results revealed that the slit-shape pores existing in nanoflake-assembled Al2O3 were responsible for the small particle size and high Ce/Zr surface ratio of supported CeO2-ZrO2 species. The dispersion of Ce1-xZrx(OH)4 precursors onto Al2O3 support surface during the deposition-precipitation process was proposed. The high dispersion and large numbers of surface oxygen vacancies of the CeO2-ZrO2 species on nanoflake-assembled Al2O3 contributed to the excellent catalytic performance in oxidative dehydrogenation of ethylbenzene with CO2. This kind of special Al2O3 is expected to be a promising support for preparing highly dispersed metal/metal oxide catalysts.

  17. Synthesis of defect-rich, (001) faceted-ZnO nanorod on a FTO substrate as efficient photocatalysts for dehydrogenation of isopropanol to acetone

    Science.gov (United States)

    Tan, Sin Tee; Umar, Akrajas Ali; Salleh, Muhamad Mat

    2016-06-01

    Highly oriented ZnO nanorod was successfully synthesised on Ag nanoseed coated FTO substrate via a microwave hydrolysis approach. It was found that the morphology and the optical properties of the ZnO nanorod are strongly influenced by the power of the microwave irradiation used during the growth process. The aspect ratio of the nanorods changed from high to low with the increasing of microwave power. It was also found that the optical band gap of the ZnO nanorod red shifted with the increasing of the microwave power, reflecting an excellent tune ability of the optical properties of ZnO nanorods. The photocatalytic activity of these unique nanorod was evaluated by a dehydrogenation process of isopropanol to acetone in the presence of ZnO nanorod. It was found that the ZnO nanorod exhibited an excellent catalytic performance by showing an ability to accelerate the production of 0.031 mol L-1 of acetone within only 35 min or 0.9 mmol L-1 min-1 from isopropyl alcohol dehydrogenation. It was almost no conversion from isopropyl alcohol when ZnO nanorods was absence during the reaction. In this report, a detailed mechanism of ZnO nanorod formation and the relationship between morphology and optical energy band gap are described.

  18. Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield

    Directory of Open Access Journals (Sweden)

    Paulo Jardel P. Araújo

    2016-01-01

    Full Text Available Styrene is an important monomer in the manufacture of thermoplastic. Most of it is produced by the catalytic dehydrogenation of ethylbenzene. In this process that depends on reversible reactions, the yield is usually limited by the establishment of thermodynamic equilibrium in the reactor. The styrene yield can be increased by using a hybrid process, with reaction and separation simultaneously. It is proposed using permselective composite membrane to remove hydrogen and thus suppress the reverse and secondary reactions. This paper describes the simulation of a dehydrogenation process carried out in a tubular fixed-bed reactor wrapped in a permselective composite membrane. A mathematical model was developed, incorporating the various mass transport mechanisms found in each of the membrane layers and in the catalytic fixed bed. The effects of the reactor feed conditions (temperature, steam-to-oil ratio, and the weight hourly space velocity, the fixed-bed geometry (length, diameter, and volume, and the membrane geometry (thickness of the layers on the styrene yield were analyzed. These variables were used to determine experimental conditions that favour the production of styrene. The simulation showed that an increase of 40.98% in the styrene yield, compared to a conventional fixed-bed process, could be obtained by wrapping the reactor in a permselective composite membrane.

  19. Organometallic model complexes elucidate the active gallium species in alkane dehydrogenation catalysts based on ligand effects in Ga K-edge XANES

    Energy Technology Data Exchange (ETDEWEB)

    Getsoian, Andrew “Bean”; Das, Ujjal; Camacho-Bunquin, Jeffrey; Zhang, Guanghui; Gallagher, James R.; Hu, Bo; Cheah, Singfoong; Schaidle, Joshua A.; Ruddy, Daniel A.; Hensley, Jesse E.; Krause, Theodore R.; Curtiss, Larry A.; Miller, Jeffrey T.; Hock, Adam S.

    2016-01-01

    Gallium-modified zeolites are known catalysts for the dehydrogenation of alkanes, reactivity that finds industrial application in the aromatization of light alkanes by Ga-ZSM5. While the role of gallium cations in alkane activation is well known, the oxidation state and coordination environment of gallium under reaction conditions has been the subject of debate. Edge shifts in Ga K-edge XANES spectra acquired under reaction conditions have long been interpreted as evidence for reduction of Ga(III) to Ga(I). However, a change in oxidation state is not the only factor that can give rise to a change in the XANES spectrum. In order to better understand the XANES spectra of working catalysts, we have synthesized a series of molecular model compounds and grafted surface organometallic Ga species and compared their XANES spectra to those of gallium-based catalysts acquired under reducing conditions. We demonstrate that changes in the identity and number of gallium nearest neighbors can give rise to changes in XANES spectra similar to those attributed in literature to changes in oxidation state. Specifically, spectral features previously attributed to Ga(I) may be equally well interpreted as evidence for low-coordinate Ga(III) alkyl or hydride species. These findings apply both to gallium-impregnated zeolite catalysts and to silica-supported single site gallium catalysts, the latter of which is found to be active and selective for dehydrogenation of propane and hydrogenation of propylene.

  20. ED-XAS Data Reveal In-situ Time-Resolved Adsorbate Coverage on Supported Molybdenum Oxide Catalysts during Propane Dehydrogenation

    Science.gov (United States)

    Ramaker, David; Gatewood, Daniel; Beale, Andrew M.; Weckhuysen, Bert M.

    2007-02-01

    Energy-Dispersive X-ray Absorption Spectroscopy (ED-XAS) data combined with UV/Vis, Raman, and mass spectrometry data on alumina- and silica-supported molybdenum oxide catalysts under propane dehydrogenation conditions have been previously reported. A novel Δμ adsorbate isolation technique was applied here to the time-resolved (0.1 min) Mo K-edge ED-XAS data by taking the difference of absorption, μ, at t>1 against the initial time, t=0. Further, full multiple scattering calculations using the FEFF 8.0 code are performed to interpret the Δμ signatures. The resulting difference spectra and interpretation provide real time propane coverage and O depletion at the MoOn surface. The propane coverage is seen to correlate with the propene and/or coke production, with the maximum coke formation occurring when the propane coverage is the largest. Combined, these data give unprecedented insight into the complicated dynamics for propane dehydrogenation.

  1. In-situ catalyzation approach for enhancing the hydrogenation/dehydrogenation kinetics of MgH2 powders with Ni particles

    Science.gov (United States)

    El-Eskandarany, M. Sherif; Shaban, Ehab; Ali, Naser; Aldakheel, Fahad; Alkandary, Abdullah

    2016-11-01

    One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides nanocrystalline powders. According to its high hydrogen capacity and low cost of production, magnesium hydride (MgH2) is a desired hydrogen storage system. Its slow hydrogenation/dehydrogenation kinetics and high thermal stability are the major barriers restricting its usage in real applications. Amongst the several methods used for enhancing the kinetics behaviors of MgH2 powders, mechanically milling the powders with one or more catalyst species has shown obvious advantages. Here we are proposing a new approach for gradual doping MgH2 powders with Ni particles upon ball milling the powders with Ni-balls milling media. This proposed is-situ method showed mutually beneficial for overcoming the agglomeration of catalysts and the formation of undesired Mg2NiH4 phase. Moreover, the decomposition temperature and the corresponding activation energy showed low values of 218 °C and 75 kJ/mol, respectively. The hydrogenation/dehydrogenation kinetics examined at 275 °C of the powders milled for 25 h took place within 2.5 min and 8 min, respectively. These powders containing 5.5 wt.% Ni performed 100-continuous cycle-life time of hydrogen charging/discharging at 275 °C within 56 h without failure or degradation.

  2. Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst

    Directory of Open Access Journals (Sweden)

    Miguel Menéndez

    2013-05-01

    Full Text Available Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR, where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500–575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol−1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB. The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen, the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors.

  3. Phosphorus Deficiency in Ducklins

    Institute of Scientific and Technical Information of China (English)

    CuiHengmin; LuoLingping

    1995-01-01

    20 one-day-old Tianfu ducklings were fed on a natural diet deficient in phosphorus(Ca 0.80%,P 0.366%)for three weeks and examined for signs and lesions.Signs began to appear at the age of one week,and became serous at two weeks.13 ducklings died during the experiment.Morbidity was 100% and mortality was 65%.The affected ducklings mainly showed leg weakness,severe lamencess,deprssion,lack of appetite and stunted growth,The serum alkaline phosphatase activities increased markedly.The serum phosphorus concentration,tibial ash,ash calcium and phosphorus content decreased obviously.At necropsy,maxillae and ribe were soft,and the latter was crooked.Long ones were soft and broke easily.The hypertrophic zone of the growth-plate in the epiphysis of long ones was lengthened and osteoid tissue increased in the metaphyseal spongiosa histopathologically.The above mentioned symptoms and lesions could be prevented by adding phosphorus to the natural deficient diet(up to 0.65%),The relationship between lesions and signs,pathomorphological characterisation and pathogensis were also discussed in this paper.

  4. Glucose-6-phosphatase deficiency

    Directory of Open Access Journals (Sweden)

    Labrune Philippe

    2011-05-01

    Full Text Available Abstract Glucose-6-phosphatase deficiency (G6P deficiency, or glycogen storage disease type I (GSDI, is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea. Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty, generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency. GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib. Mutations in the genes G6PC (17q21 and SLC37A4 (11q23 respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most

  5. Glucose-6-phosphatase deficiency.

    Science.gov (United States)

    Froissart, Roseline; Piraud, Monique; Boudjemline, Alix Mollet; Vianey-Saban, Christine; Petit, François; Hubert-Buron, Aurélie; Eberschweiler, Pascale Trioche; Gajdos, Vincent; Labrune, Philippe

    2011-05-20

    Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea). Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty), generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma) and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency). GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia) which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib). Mutations in the genes G6PC (17q21) and SLC37A4 (11q23) respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most commonly confirmed

  6. Management of Iron Deficiency Anemia

    OpenAIRE

    Jimenez, Kristine; Kulnigg-Dabsch, Stefanie; Gasche, Christoph

    2015-01-01

    Anemia affects one-fourth of the world’s population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blo...

  7. [Iron deficiency and digestive disorders].

    Science.gov (United States)

    Cozon, G J N

    2014-11-01

    Iron deficiency anemia still remains problematic worldwide. Iron deficiency without anemia is often undiagnosed. We reviewed, in this study, symptoms and syndromes associated with iron deficiency with or without anemia: fatigue, cognitive functions, restless legs syndrome, hair loss, and chronic heart failure. Iron is absorbed through the digestive tract. Hepcidin and ferroportin are the main proteins of iron regulation. Pathogenic micro-organisms or intestinal dysbiosis are suspected to influence iron absorption. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  8. Nutritional deficiencies after bariatric surgery.

    Science.gov (United States)

    Bal, Bikram S; Finelli, Frederick C; Shope, Timothy R; Koch, Timothy R

    2012-09-01

    Lifestyle intervention programmes often produce insufficient weight loss and poor weight loss maintenance. As a result, an increasing number of patients with obesity and related comorbidities undergo bariatric surgery, which includes approaches such as the adjustable gastric band or the 'divided' Roux-en-Y gastric bypass (RYGB). This Review summarizes the current knowledge on nutrient deficiencies that can develop after bariatric surgery and highlights follow-up and treatment options for bariatric surgery patients who develop a micronutrient deficiency. The major macronutrient deficiency after bariatric surgery is protein malnutrition. Deficiencies in micronutrients, which include trace elements, essential minerals, and water-soluble and fat-soluble vitamins, are common before bariatric surgery and often persist postoperatively, despite universal recommendations on multivitamin and mineral supplements. Other disorders, including small intestinal bacterial overgrowth, can promote micronutrient deficiencies, especially in patients with diabetes mellitus. Recognition of the clinical presentations of micronutrient deficiencies is important, both to enable early intervention and to minimize long-term adverse effects. A major clinical concern is the relationship between vitamin D deficiency and the development of metabolic bone diseases, such as osteoporosis or osteomalacia; metabolic bone diseases may explain the increased risk of hip fracture in patients after RYGB. Further studies are required to determine the optimal levels of nutrient supplementation and whether postoperative laboratory monitoring effectively detects nutrient deficiencies. In the absence of such data, clinicians should inquire about and treat symptoms that suggest nutrient deficiencies.

  9. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra

    NARCIS (Netherlands)

    Marashdeh, A.; Frankcombe, T.J.

    2008-01-01

    The dehydrogenation enthalpies of Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4 have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski’s direct method. The dehydrog

  10. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra.

    Science.gov (United States)

    Marashdeh, Ali; Frankcombe, Terry J

    2008-06-21

    The dehydrogenation enthalpies of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski's direct method. The dehydrogenation of Ca(AlH(4))(2) is exothermic, indicating a metastable hydride. Calculations for CaAlH(5) including ZPE effects indicate that it is not stable enough for a hydrogen storage system operating near ambient conditions. The destabilized combination of LiBH(4) with CaH(2) is a promising system after ZPE-corrected enthalpy calculations. The calculations confirm that including ZPE effects in the harmonic approximation for the dehydrogenation of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) has a significant effect on the calculated reaction enthalpy. The contribution of ZPE to the dehydrogenation enthalpies of Ca(AlH(4))(2) and CaAlH(5) calculated by the direct method phonon analysis was compared to that calculated by the frozen-phonon method. The crystal structure of CaAlH(5) is presented in the more useful standard setting of P2(1)c symmetry and the phonon density of states of CaAlH(5), significantly different to other common complex metal hydrides, is rationalized.

  11. In situ UV–Vis diffuse reflectance spectroscopy — on line activity measurements of supported chromium oxide catalysts: relating isobutane dehydrogenation activity with Cr-speciation via experimental design

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Verberckmoes, A.A.; Debaere, J.; Ooms, K.; Langhans, I.; Schoonheydt, R.A.

    2000-01-01

    The dehydrogenation of isobutane over supported chromium oxide catalysts was studied by a combination of in situ UV–Vis diffuse reflectance spectroscopy and on line GC analysis. A well-defined set of experiments, based on an experimental design, was carried out to develop mathematical models, which

  12. Iron deficiency and iron deficiency anemia in women.

    Science.gov (United States)

    Coad, Jane; Pedley, Kevin

    2014-01-01

    Iron deficiency is one of the most common nutritional problems in the world and disproportionately affects women and children. Stages of iron deficiency can be characterized as mild deficiency where iron stores become depleted, marginal deficiency where the production of many iron-dependent proteins is compromised but hemoglobin levels are normal and iron deficiency anemia where synthesis of hemoglobin is decreased and oxygen transport to the tissues is reduced. Iron deficiency anemia is usually assessed by measuring hemoglobin levels but this approach lacks both specificity and sensitivity. Failure to identify and treat earlier stages of iron deficiency is concerning given the neurocognitive implications of iron deficiency without anemia. Most of the daily iron requirement is derived from recycling of senescent erythrocytes by macrophages; only 5-10 % comes from the diet. Iron absorption is affected by inhibitors and enhancers of iron absorption and by the physiological state. Inflammatory conditions, including obesity, can result in iron being retained in the enterocytes and macrophages causing hypoferremia as a strategic defense mechanism to restrict iron availability to pathogens. Premenopausal women usually have low iron status because of iron loss in menstrual blood. Conditions which further increase iron loss, compromise absorption or increase demand, such as frequent blood donation, gastrointestinal lesions, athletic activity and pregnancy, can exceed the capacity of the gastrointestinal tract to upregulate iron absorption. Women of reproductive age are at particularly high risk of iron deficiency and its consequences however there is a controversial argument that evolutionary pressures have resulted in an iron deficient phenotype which protects against infection.

  13. Iodine deficiency in Europe.

    Science.gov (United States)

    Delange, F

    1995-01-18

    Iodine is a trace element present in the human body in minute amounts (15-20 mg in adults, i.e. 0.0285 x 10(-3)% of body weight). The only confirmed function of iodine is to constitute an essential substrate for the synthesis of thyroid hormones, tetraiodothyronine, thyroxine or T4 and triiodothyronine, T3 (1). In thyroxine, iodine is 60% by weight. Thyroid hormones, in turn, play a decisive role in the metabolism of all cells of the organism (2) and in the process of early growth and development of most organs, especially of the brain (3). Brain development in humans occurs from fetal life up to the third postnatal year (4). Consequently, a deficit in iodine and/or in thyroid hormones occurring during this critical period of life will result not only in the slowing down of the metabolic activities of all the cells of the organism but also in irreversible alterations in the development of the brain. The clinical consequence will be mental retardation (5). When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur (Table 1), including thyroid function abnormalities and, when iodine deficiency is severe, endemic goiter and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death, and infant mortality. These complications, which constitute an hindrance to the development of the affected population, are grouped under the general heading of Iodine Deficiency Disorders, IDD (6). Broad geographic areas exist in which the population is affected by IDD.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Iron deficiency anemia in children

    OpenAIRE

    Pochinok, T. V.

    2016-01-01

    In the article the role of iron in the human body is highlighted. The mechanism of development of iron deficiency states, their consequences and the basic principles of diagnosis and correction of children of different ages are shown.Key words: children, iron deficiency anemia, treatment.

  15. Iron deficiency and cardiovascular disease

    NARCIS (Netherlands)

    von Haehling, Stephan; Jankowska, Ewa A.; van Veldhuisen, Dirk J.; Ponikowski, Piotr; Anker, Stefan D.

    2015-01-01

    Iron deficiency affects up to one-third of the world's population, and is particularly common in elderly individuals and those with certain chronic diseases. Iron excess can be detrimental in cardiovascular illness, and research has now also brought anaemia and iron deficiency into the focus of card

  16. Newborn screening for MCAD deficiency

    DEFF Research Database (Denmark)

    Horvath, Gabriella A; Davidson, A G F; Stockler-Ipsiroglu, Sylvia G

    2008-01-01

    BACKGROUND: Medium Chain Acyl-CoA Dehydrogenase (MCAD) Deficiency is an autosomal recessive disorder of fatty acid oxidation, with potential fatal outcome. MCAD deficiency is diagnosed by acylcarnitine analysis on newborn screening blood spot cards by tandem mass spectrometry. Early diagnosis of ...

  17. Iron deficiency anemia in children.

    Science.gov (United States)

    Subramaniam, Girish; Girish, Meenakshi

    2015-06-01

    Iron deficiency is not just anemia; it can be responsible for a long list of other manifestations. This topic is of great importance, especially in infancy and early childhood, for a variety of reasons. Firstly, iron need is maximum in this period. Secondly, diet in infancy is usually deficient in iron. Thirdly and most importantly, iron deficiency at this age can result in neurodevelopmental and cognitive deficits, which may not be reversible. Hypochromia and microcytosis in a complete blood count (CBC) makes iron deficiency anemia (IDA) most likely diagnosis. Absence of response to iron should make us look for other differential diagnosis like β thalassemia trait and anemia of chronic disease. Celiac disease is the most important cause of true IDA not responding to oral iron therapy. While oral ferrous sulphate is the cheapest and most effective therapy for IDA, simple nonpharmacological and pharmacological measures can go a long way in prevention of iron deficiency.

  18. Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Amende, Max, E-mail: max.amende@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Kaftan, Andre, E-mail: andre.kaftan@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Bachmann, Philipp, E-mail: philipp.bachmann@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Brehmer, Richard, E-mail: richard.brehmer@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Preuster, Patrick, E-mail: patrick.preuster@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Koch, Marcus, E-mail: marcus.koch@crt.cbi.uni-erlangen.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); and others

    2016-01-01

    Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al{sub 2}O{sub 3} model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al{sub 2}O{sub 3} catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al{sub 2}O{sub 3} model catalyst and

  19. Genetics Home Reference: protein C deficiency

    Science.gov (United States)

    ... Management Genetic Testing (1 link) Genetic Testing Registry: Thrombophilia, hereditary, due to protein C deficiency, autosomal dominant ... my area? Other Names for This Condition hereditary thrombophilia due to protein C deficiency PROC deficiency Related ...

  20. Genetics Home Reference: glutathione synthetase deficiency

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions glutathione synthetase deficiency glutathione synthetase deficiency Enable Javascript to view the expand/ ... boxes. Download PDF Open All Close All Description Glutathione synthetase deficiency is a disorder that prevents the ...

  1. Genetics Home Reference: GLUT1 deficiency syndrome

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions GLUT1 deficiency syndrome GLUT1 deficiency syndrome Enable Javascript to view the expand/ ... boxes. Download PDF Open All Close All Description GLUT1 deficiency syndrome is a disorder affecting the nervous ...

  2. Genetics Home Reference: familial HDL deficiency

    Science.gov (United States)

    ... Genetics Home Health Conditions familial HDL deficiency familial HDL deficiency Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Familial HDL deficiency is a condition characterized by low levels ...

  3. Genetics Home Reference: isolated growth hormone deficiency

    Science.gov (United States)

    ... Genetic Testing (4 links) Genetic Testing Registry: Ateleiotic dwarfism Genetic Testing Registry: Autosomal dominant isolated somatotropin deficiency ... in my area? Other Names for This Condition dwarfism, growth hormone deficiency dwarfism, pituitary growth hormone deficiency ...

  4. Genetics Home Reference: lactate dehydrogenase deficiency

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions lactate dehydrogenase deficiency lactate dehydrogenase deficiency Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Lactate dehydrogenase deficiency is a condition that affects how the ...

  5. Iron deficiency and thrombocytosis.

    Science.gov (United States)

    Holbro, A; Volken, T; Buser, A; Sigle, J P; Halter, J P; Passweg, J R; Tichelli, A; Infanti, L

    2017-01-01

    According to many textbooks, iron deficiency (ID) is associated with reactive thrombocytosis. In this study, we aimed to investigate the correlation between serum ferritin levels and platelet counts in a large cohort of healthy blood donors. We included all whole blood and apheresis donors aged 18 years or older with at least one ferritin measurement and one platelet count performed at the same visit between 1996 and 2014. A total of 130 345 blood counts and ferritin measurements obtained from 22 046 healthy donors were analysed. Overall, no correlation between serum ferritin and platelet count was observed (r = -0.03, ρ = 0.04 for males, and r = 0.01, ρ = -0.02 for females, respectively). Associations remained clinically negligible after adjusting for age, time since previous blood donation, number of donations and restricting the analysis to ferritin deciles. In this large, retrospective single-centre study, correlations between low ferritin and platelet count in a large and homogeneous cohort of healthy donors were negligible. Further studies in patients with more severe anaemia and patients with inflammation are warranted. © 2016 International Society of Blood Transfusion.

  6. Iron Deficiency Anemia in Pregnancy.

    Science.gov (United States)

    Breymann, Christian

    2015-10-01

    Anemia is a common problem in obstetrics and perinatal care. Any hemoglobin below 10.5 g/dL can be regarded as true anemia regardless of gestational age. Reasons for anemia in pregnancy are mainly nutritional deficiencies, parasitic and bacterial diseases, and inborn red blood cell disorders such as thalassemias. The main cause of anemia in obstetrics is iron deficiency, which has a worldwide prevalence between estimated 20%-80% and consists of a primarily female population. Stages of iron deficiency are depletion of iron stores, iron-deficient erythropoiesis without anemia, and iron deficiency anemia, the most pronounced form of iron deficiency. Pregnancy anemia can be aggravated by various conditions such as uterine or placental bleedings, gastrointestinal bleedings, and peripartum blood loss. In addition to the general consequences of anemia, there are specific risks during pregnancy for the mother and the fetus such as intrauterine growth retardation, prematurity, feto-placental miss ratio, and higher risk for peripartum blood transfusion. Besides the importance of prophylaxis of iron deficiency, the main therapy options for the treatment of pregnancy anemia are oral iron and intravenous iron preparations.

  7. Catalytic Dehydrogenation of n-Butane over V/SiO2 Catalyst: A Comparison with Cr/SiO2 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Xu Yuebing; Fu Wenting; Lu Jiangyin; Wang Jide

    2008-01-01

    V/SiO2 catalysts compared to Cr/SiO2 catalysts were studied for dehydrogenation of n-butane to butenes.Several methods for characterization of catalysts such as FT-IR,UV-vis and Raman spectroscopies were used.Some differences between two catalysts were showed,including the performances of catalysts,distribution of products and mechanism of reactions.The results showed that prepared catalysts with 12m% of active component loading all demonstrated best conversion of n-butane to butene at a reaction temperature of around 590℃.Two different reaction mechanisms were mentioned to well explain why iso-butene was produced on V/SiO2 catalysts but not on Cr/SiO2 catalysts.

  8. Synthesis and characterization of TiO2 –SiO2 nanoparticles as catalyst for dehydrogenation of 1,4-dihydropyridines

    Indian Academy of Sciences (India)

    F Farzaneh; L Jafarie Fourozune

    2014-02-01

    Nanoparticles of binary TiO2–SiO2 mixed oxides was prepared via sol–gel method using tetraethylorthosilicate (TEOS) and titanium isopropoxide (TIPP) in different reaction conditions (solvent and pH) using ammonium hyhdroxide, acetic acid, sodium hydroxide, ethyleneglycol and polyethylene glycol followed by calcination at 850–970° C. The morphologies, structures and chemical compositions were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transmission infrared spectroscopy (FTIR) techniques. The catalytic activity of the obtained nanomaterials was explored for the dehydrogenation of 1,4-dihydropyridines (1,4-DHPs). Observation of 86–100% conversion and 100% selectivity towards the formation of desired products with prepared nanoparticles will be discussed here.

  9. Core-shell structured nanospheres with mesoporous silica shell and Ni core as a stable catalyst for hydrolytic dehydrogenation of ammonia borane

    Institute of Scientific and Technical Information of China (English)

    Hua; Liu; Changyan; Cao; Ping; Li; Yu; Yu; Weiguo; Song

    2014-01-01

    Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5,and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.

  10. Probing the electronic structure of M-graphene oxide (M = Ni, Co, NiCo) catalysts for hydrolytic dehydrogenation of ammonia borane

    Science.gov (United States)

    Zhao, Binhua; Liu, Jinyin; Zhou, Litao; Long, Dan; Feng, Kun; Sun, Xuhui; Zhong, Jun

    2016-01-01

    Various metal elements (M = Ni, Co, NiCo) were dispersed on graphene oxide (GO) to form the M-GO hybrids by a facile way. The hybrids showed good catalytic activities in the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3), which were significantly enhanced when compared to the metal nanoparticles or GO alone. The electronic structure of the hybrids has been probed by scanning transmission X-ray microscopy (STXM). The distribution of metal elements was clearly imaged with identical electronic structure. Moreover, an interfacial interaction between metal and GO was observed with the peak intensity proportional to the catalytic performance in the hydrolysis of AB. The results provide new insight into the enhanced performance of the M-GO hybrids and may help for the design of advanced catalysts.

  11. Mechanical and Thermal Dehydrogenation of Lithium Alanate (LiAlH4 and Lithium Amide (LiNH2 Hydride Composites

    Directory of Open Access Journals (Sweden)

    Leszek Zbroniec

    2012-04-01

    Full Text Available Hydrogen storage properties of the (nLiAlH4 + LiNH2 hydride composite where n = 1, 3, 11.5 and 30, synthesized by high energy ball milling have been investigated. The composite with the molar ratio n = 1 releases large quantities of H2 (up to ~5 wt.% during ball milling up to 100–150 min. The quantity of released H2 rapidly decreases for the molar ratio n = 3 and is not observed for n = 11.5 and 30. The XRD studies indicate that the H2 release is a result of a solid state decomposition of LiAlH4 into (1/3Li3AlH6 + (2/3Al + H2 and subsequently decomposition of (1/3Li3AlH6 into LiH + (1/3Al + 0.5H2. Apparently, LiAlH4 is profoundly destabilized during ball milling by the presence of a large quantity of LiNH2 (37.7 wt.% in the n = 1 composite. The rate of dehydrogenation at 100–170 °C (at 1 bar H2 is adversely affected by insufficient microstructural refinement, as observed for the n = 1 composite, which was milled for only 2 min to avoid H2 discharge during milling. XRD studies show that isothermal dehydrogenation of (nLiAlH4 + LiNH2 occurs by the same LiAlH4 decomposition reactions as those found during ball milling. The ball milled n = 1 composite stored under Ar at 80 °C slowly discharges large quantities of H2 approaching 3.5 wt.% after 8 days of storage.

  12. In vitro analysis of the monolignol coupling mechanism using dehydrogenative polymerization in the presence of peroxidases and controlled feeding ratios of coniferyl and sinapyl alcohol.

    Science.gov (United States)

    Moon, Sun-Joo; Kwon, Mi; Choi, Donha; Won, Keehoon; Kim, Yong Hwan; Choi, In-Gyu; Choi, Joon Weon

    2012-10-01

    In this study, dehydrogenative polymers (DHP) were synthesized in vitro through dehydrogenative polymerization using different ratios of coniferyl alcohol (CA) and sinapyl alcohol (SA) (10:0, 8:2, 6:4, 2:8, 0:10), in order to investigate the monolignol coupling mechanism in the presence of horseradish peroxidase (HRP), Coprinus cinereus peroxidase (CiP) or soybean peroxidase (SBP) with H(2)O(2), respectively. The turnover capacities of HRP, CiP and SBP were also measured for coniferyl alcohol (CA) and sinapyl alcohol (SA), and CiP and SBP were found to have the highest turnover capacity for CA and SA, respectively. The yields of HRP-catalyzed DHP (DHP-H) and CiP-catalyzed DHP (DHP-C) were estimated between ca. 7% and 72% based on the original weights of CA/SA in these synthetic conditions. However, a much lower yield of SBP-catalyzed DHP (DHP-S) was produced compared to that of DHP-H and DHP-C. In general, the DHP yields gradually increased as the ratio of CA/SA increased. The average molecular weight of DHP-H also increased with increasing CA/SA ratios, while those of DHP-C and DHP-S were not influenced by the ratios of monolignols. The frequency of β-O-4 linkages in the DHPs decreased with increasing CA/SA ratios, indicating that the formation of β-O-4 linkages during DHP synthesis was influenced by peroxidase type.

  13. Metallic glassy Zr70Ni20Pd10 powders for improving the hydrogenation/dehydrogenation behavior of MgH2.

    Science.gov (United States)

    El-Eskandarany, M Sherif

    2016-05-25

    Because of its low density, storage of hydrogen in the gaseous and liquids states possess technical and economic challenges. One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides. Magnesium hydride (MgH2) remains the best hydrogen storage material due to its high hydrogen capacity and low cost of production. Due to its high activation energy and poor hydrogen sorption/desorption kinetics at moderate temperatures, the pure form of MgH2 is usually mechanically treated by high-energy ball mills and catalyzed with different types of catalysts. These steps are necessary for destabilizing MgH2 to enhance its kinetics behaviors. In the present work, we used a small mole fractions (5 wt.%) of metallic glassy of Zr70Ni20Pd10 powders as a new enhancement agent to improve its hydrogenation/dehydrogenation behaviors of MgH2. This short-range ordered material led to lower the decomposition temperature of MgH2 and its activation energy by about 121 °C and 51 kJ/mol, respectively. Complete hydrogenation/dehydrogenation processes were successfully achieved to charge/discharge about 6 wt.%H2 at 100 °C/200 °C within 1.18 min/3.8 min, respectively. In addition, this new nanocomposite system shows high performance of achieving continuous 100 hydrogen charging/discharging cycles without degradation.

  14. Metallic glassy Zr70Ni20Pd10 powders for improving the hydrogenation/dehydrogenation behavior of MgH2

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2016-05-01

    Because of its low density, storage of hydrogen in the gaseous and liquids states possess technical and economic challenges. One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides. Magnesium hydride (MgH2) remains the best hydrogen storage material due to its high hydrogen capacity and low cost of production. Due to its high activation energy and poor hydrogen sorption/desorption kinetics at moderate temperatures, the pure form of MgH2 is usually mechanically treated by high-energy ball mills and catalyzed with different types of catalysts. These steps are necessary for destabilizing MgH2 to enhance its kinetics behaviors. In the present work, we used a small mole fractions (5 wt.%) of metallic glassy of Zr70Ni20Pd10 powders as a new enhancement agent to improve its hydrogenation/dehydrogenation behaviors of MgH2. This short-range ordered material led to lower the decomposition temperature of MgH2 and its activation energy by about 121 °C and 51 kJ/mol, respectively. Complete hydrogenation/dehydrogenation processes were successfully achieved to charge/discharge about 6 wt.%H2 at 100 °C/200 °C within 1.18 min/3.8 min, respectively. In addition, this new nanocomposite system shows high performance of achieving continuous 100 hydrogen charging/discharging cycles without degradation.

  15. Genetics Home Reference: hereditary antithrombin deficiency

    Science.gov (United States)

    ... Merck Manual Home Edition for Patients and Caregivers: Thrombophilia National Blood Clot Alliance: Antithrombin Deficiency Orphanet: Hereditary thrombophilia due to congenital antithrombin deficiency Patient Support and ...

  16. Main: 1W07 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1; Arabidopsis Thaliana Molecule: Acyl-Coa Oxidase; Chain: A, B; Mutation: Yes; Engineered: Yes Oxidoreducta...AGSRHAFEVSDRIARLVASDPVFEKSNRARLSRKELFKSTLRKCAHAFKRIIELRLNEEEAGRLRHFIDQPAYVDLHWGMFVPAI...YLWCSGLPELFAVYVPACTYEGDNVVLQLQVARFLMKTVAQLGSGKVPVGTTAYMGRAAHLLQCRSGVQKAEDWLNPDVVLEAFEARALRMAVTCAKNLSKFENQEQGFQELLADLVEAAI

  17. Gel-assisted crystallization of [Ir 4 (IMe) 7 (CO)H 10 ] 2+ and [Ir 4 (IMe) 8 H 9 ] 3+ clusters derived from catalytic glycerol dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Sharninghausen, Liam S. [Yale University; New Haven, USA; Mercado, Brandon Q. [Yale University; New Haven, USA; Crabtree, Robert H. [Yale University; New Haven, USA; Balcells, David [The Centre for Theoretical and Computational Chemistry (CTCC); Department of Chemistry, University of Oslo; N-0315 Oslo, Norway; Campos, Jesús [Yale University; New Haven, USA

    2015-01-01

    Two unique Ir4clusters isolated during catalytic glycerol dehydrogenation, crystallized using aqueous and organic gel matrices and displaying remarkable structural features are described.

  18. [Niacin deficiency and cutaneous immunity].

    Science.gov (United States)

    Ikenouchi-Sugita, Atsuko; Sugita, Kazunari

    2015-01-01

    Niacin, also known as vitamin B3, is required for the synthesis of coenzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). Niacin binds with G protein-coupled receptor (GPR) 109A on cutaneous Langerhans cells and causes vasodilation with flushing in head and neck area. Niacin deficiency due to excessive alcohol consumption, certain drugs or inadequate uptake in diet causes pellagra, a photosensitivity dermatitis. Recently several studies have revealed the mechanism of photosensitivity in niacin deficiency, which may pave a way for new therapeutic approaches. The expression level of prostaglandin E synthase (PTGES) is up-regulated in the skin of both pellagra patients and niacin deficient pellagra mouse models. In addition, pellagra is mediated through prostaglandin E₂-EP4 (PGE₂-EP4) signaling via reactive oxygen species (ROS) production in keratinocytes. In this article, we have reviewed the role of niacin in immunity and the mechanism of niacin deficiency-induced photosensitivity.

  19. Genetics Home Reference: transcobalamin deficiency

    Science.gov (United States)

    ... deficiency often develop a blood disorder called megaloblastic anemia . Megaloblastic anemia results in a shortage of red blood cells, ... and Prevention: Intellectual Disability (PDF) Children's Hospital Boston: Megaloblastic Pernicious Anemia Children's Hospital Boston: White Blood Cell Disorders CLIMB: ...

  20. Genetics Home Reference: prolidase deficiency

    Science.gov (United States)

    ... Cetta G, Forlino A. Human prolidase and prolidase deficiency: an overview on the characterization of the enzyme involved in proline recycling and on the effects of its mutations. Amino Acids. 2008 Nov;35(4):739-52. doi: 10. ...

  1. Genetics Home Reference: proopiomelanocortin deficiency

    Science.gov (United States)

    ... energy from food taken into the body and energy spent by the body. The correct balance is important to control eating and weight. POMC gene mutations that cause POMC deficiency result in production ...

  2. Helicobacterpy loriinfection and micronutrient deficiencies

    Institute of Scientific and Technical Information of China (English)

    Javed Yakoob; Wasim Jafri; Shahab Abid

    2003-01-01

    It is known that deficiencies of micronutrients due to infections increase morbidity and mortality. This phenomenon depicts itself conspicuously in developing countries.Deficiencies of iron, vitamins A, E, C, B12, etc are widely prevalent among populations living in the third world countries. Helicobacterpylori (Hpylori) infection has a high prevalence throughout the world. Deficiencies of several micronutrients due to Hpylori infection may be concomitantly present and vary from subtle sub-clinical states to severe clinical disorders. These essential trace elementsl micronutrients are involved in host defense mechanisms,maintaining epithelial cell integrity, glycoprotein synthesis,transport mechanisms, myocardial contractility, brain development, cholesterol and glucose metabolism. In this paper Hpyloriinfection in associaed with various micronutrients deficiencies is briefly reviewed.

  3. Vitamin D deficiency in adolescents

    OpenAIRE

    Ashraf T Soliman; Vincenzo De Sanctis; Rania Elalaily; Said Bedair; Islam Kassem

    2014-01-01

    The prevalence of severe vitamin D deficiency (VDD) in adolescents is variable but considerably high in many countries, especially in Middle-east and Southeast Asia. Different factors attribute to this deficiency including lack of sunlight exposure due to cultural dress codes and veiling or due to pigmented skin, and less time spent outdoors, because of hot weather, and lower vitamin D intake. A potent adaptation process significantly modifies the clinical presentation and therefore clinical ...

  4. Iron deficiency and cognitive functions

    OpenAIRE

    Jáuregui-Lobera I

    2014-01-01

    Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with...

  5. Iron deficiency and cognitive functions

    OpenAIRE

    Jáuregui-Lobera I

    2014-01-01

    Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with...

  6. Non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} on dehydrogenation high-energy ball milled MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hou, Xiaojiang; Hu, Rui; Kou, Hongchao; Li, Jinshan

    2016-11-01

    MgH{sub 2}-M (M = TiF{sub 3} or Nb{sub 2}O{sub 5} or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH{sub 2} with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH{sub 2} with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF{sub 3} and Nb{sub 2}O{sub 5} evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH{sub 2} and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH{sub 2} reduce from 417 °C to 341 °C for TiF{sub 3} and from 417 °C to 336 °C for Nb{sub 2}O{sub 5}, respectively. The desorption peak temperature reaches as low as 310 °C for MgH{sub 2} catalyzed by TiF{sub 3} coupling with Nb{sub 2}O{sub 5}. The non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH{sub 2}. - Highlights: • Catalytic surface for MgH{sub 2} is achieved by high-energy ball milling. • Non-isothermal dehydrogenation behavior of MgH{sub 2} with TiF{sub 3} and/or Nb{sub 2}O{sub 5} is illustrated. • Dehydrogenation activation energies of synergetic catalyzed MgH{sub 2} are obtained. • Synergetic catalytic-dehydrogenation mechanism of TiF{sub 3} and Nb{sub 2}O{sub 5} is proposed.

  7. Clinical manifestation of myeloperoxidase deficiency.

    Science.gov (United States)

    Lanza, F

    1998-09-01

    Myeloperoxidase (MPO), an iron-containing heme protein localized in the azurophilic granules of neutrophil granulocytes and in the lysosomes of monocytes, is involved in the killing of several micro-organisms and foreign cells, including bacteria, fungi, viruses, red cells, and malignant and nonmalignant nucleated cells. Despite the primary role of the oxygen-dependent MPO system in the destruction of certain phagocytosed microbes, subjects with total or partial MPO deficiency generally do not have an increased frequency of infections, probably because other MPO-independent mechanism(s) for microbicidal activity compensate for the lack of MPO. Infectious diseases, especially with species of Candida, have been observed predominantly in MPO-deficient patients who also have diabetes mellitus, but the frequency of such cases is very low, less than 5% of reported MPO-deficient subjects. Evidence from a number of investigators indicates that individuals with total MPO deficiency show a high incidence of malignant tumors. Since MPO-deficient PMNs exhibit in vitro a depressed lytic action against malignant human cells, it can be speculated that the neutrophil MPO system plays a central role in the tumor surveillance of the host. However, any definitive conclusion on the association between MPO deficiency and the occurrence of cancers needs to be confirmed in further clinical studies. Clinical manifestations of this disorder depend on the nature of the defect; an acquired abnormality associated with other hematological or nonhematological diseases has been occasionally described, but the primary deficiency is the form more commonly reported. Another area of interest pertinent to MPO expression is related to the use of anti-MPO monoclonal antibodies for the lineage assignment of acute leukemic cells, the definition of FAB MO acute myeloid leukemia, the identification of biphenotypic acute leukemias, and their distinction from acute leukemia with minimal phenotypic deviation

  8. EFFECT OF FREE FATTY ACIDS ON LONG-CHAIN ACYL-COA SYNTHETASE 1 EXPRESSION LEVEL AND LIPID METABOLISM IN LIVER CELLS%游离脂肪酸对肝细胞ACSL1表达及相关脂代谢的影响

    Institute of Scientific and Technical Information of China (English)

    刘艳; 施文荣; 洪振丰; 郑海音; 李颖

    2013-01-01

    目的 研究游离脂肪酸(FFA)的诱导对L02肝细胞长链脂酰CoA合成酶1(ACSL1)的表达及相关代谢的影响.方法 用含不同浓度(0.2、0.4、0.8 mmol/L) FFA的培养液诱导L02细胞48 h,Western blot检测ACSL1蛋白水平,荧光定量PCR检测ACSL1 mRNA水平,比色法测定甘油三酯(TG)含量、ATP水平和培养上清FFA浓度变化,生化法测定酮体含量和培养上清葡萄糖浓度变化.结果 FFA的诱导可显著提高ACSL1蛋白表达水平(P<0.01),但对ACSL1 mRNA水平无明显影响(P>0.05),细胞内TG含量显著升高(P<0.01或P<0.05),酮体含量显著升高(P<0.05),培养上清葡萄糖消耗显著增加(P<0.01),胞内ATP水平无明显变化(P>0.05),与0.2 mmol/L、0.4 mmol/L FFA组相比,0.8 mmol/L FFA组培养上清FFA消耗显著增加(P<0.01或P<0.05).结论 FFA通过上调ACSL1蛋白表达水平致肝细胞TG蓄积.%Objective To investigate the effect of free fatty acids (FFA) on long-chain acyl-CoA synthetase l(ACSL1) expression level and lipid metabolism in L02 cells.Methods The cells were treated by FFA (0.2,0.4,0.8 mmol/L) for 48 h.ACSL1 mRNA level was measured by quantitative real-time polymerase chain reaction (PCR) and protein level by Western blotting.Cellular triglyceride (TG),ketone bodies (Ket),ATP and consumption of FFA and glucose in culture supernatant were measured.Results Compared with normal control group,treatment of L02 cells with FFA did not affect ACSL1 mRNA expression level but significantly increased ACSL1 protein expression level.TG content,Ket level and consumption of glucose in culture supernatant were significantly higher and ATP level was not affected.Compared with 0.2 and 0.4 mmol/L FFA group,the consumption of FFA in culture supernatant was significantly higher in treatment with 0.8 mmol/L FFA.Conclusion FFA induced intracellular TG accumulation by up-regulating ACSL1 protein level in L02 cells.

  9. [Iron deficiency and iron deficiency anemia are global health problems].

    Science.gov (United States)

    Dahlerup, Jens; Lindgren, Stefan; Moum, Björn

    2015-03-10

    Iron deficiency and iron deficiency anemia are global health problems leading to deterioration in patients' quality of life and more serious prognosis in patients with chronic diseases. The cause of iron deficiency and anemia is usually a combination of increased loss and decreased intestinal absorption and delivery from iron stores due to inflammation. Oral iron is first line treatment, but often hampered by intolerance. Intravenous iron is safe, and the preferred treatment in patients with chronic inflammation and bowel diseases. The goal of treatment is normalisation of hemoglobin concentration and recovery of iron stores. It is important to follow up treatment to ensure that these objectives are met and also long-term in patients with chronic iron loss and/or inflammation to avoid recurrence of anemia.

  10. Iron deficiency in blood donors

    Directory of Open Access Journals (Sweden)

    Armando Cortés

    2005-03-01

    Full Text Available Context: Blood donation results in a substantial loss of iron (200 to 250 mg at each bleeding procedure (425 to 475 ml and subsequent mobilization of iron from body stores. Recent reports have shown that body iron reserves generally are small and iron depletion is more frequent in blood donors than in non-donors. Objective: The aim of this study was to evaluate the frequency of iron deficiency in blood donors and to establish the frequency of iron deficiency in blood donors according to sex, whether they were first-time or multi-time donors. Design: From march 20 to April 5, 2004, three hundred potential blood donors from Hemocentro del Café y Tolima Grande were studied. Diagnostic tests: Using a combination of biochemical measurements of iron status: serum ferritin (RIA, ANNAR and the hemoglobin pre and post-donation (HEMOCUE Vital technology medical . Results: The frequency of iron deficiency in potential blood donors was 5%, and blood donors accepted was 5.1%; in blood donors rejected for low hemoglobin the frequency of iron deficiency was 3.7% and accepted blood donors was 1.7% in male and 12.6% in female. The frequency of iron deficiency was higher in multi-time blood donors than in first-time blood donors, but not stadistic significative. Increase nivel accepted hemoglobina in 1 g/dl no incidence in male; in female increase of 0.5 g/dl low in 25% blood donors accepted with iron deficiency, but increased rejected innecesary in 16.6% and increased is 1 g/dl low blood donors female accepted in 58% (7/12, but increased the rejected innecesary in 35.6%. Conclusions: We conclude that blood donation not is a important factor for iron deficiency in blood donors. The high frequency of blood donors with iron deficiency found in this study suggests a need for a more accurate laboratory trial, as hemoglobin or hematocrit measurement alone is not sufficient for detecting and excluding blood donors with iron deficiency without anemia, and ajustes hacia

  11. Iron deficiency and cardiovascular disease.

    Science.gov (United States)

    von Haehling, Stephan; Jankowska, Ewa A; van Veldhuisen, Dirk J; Ponikowski, Piotr; Anker, Stefan D

    2015-11-01

    Iron deficiency affects up to one-third of the world's population, and is particularly common in elderly individuals and those with certain chronic diseases. Iron excess can be detrimental in cardiovascular illness, and research has now also brought anaemia and iron deficiency into the focus of cardiovascular medicine. Data indicate that iron deficiency has detrimental effects in patients with coronary artery disease, heart failure (HF), and pulmonary hypertension, and possibly in patients undergoing cardiac surgery. Around one-third of all patients with HF, and more than one-half of patients with pulmonary hypertension, are affected by iron deficiency. Patients with HF and iron deficiency have shown symptomatic improvements from intravenous iron administration, and some evidence suggests that these improvements occur irrespective of the presence of anaemia. Improved exercise capacity has been demonstrated after iron administration in patients with pulmonary hypertension. However, to avoid iron overload and T-cell activation, it seems that recipients of cardiac transplantations should not be treated with intravenous iron preparations.

  12. Effect of Fe additive on the hydrogenation-dehydrogenation properties of 2LiH + MgB2/2LiBH4 + MgH2 system

    Science.gov (United States)

    Puszkiel, J. A.; Gennari, F. C.; Larochette, P. Arneodo; Ramallo-López, J. M.; Vainio, U.; Karimi, F.; Pranzas, P. K.; Troiani, H.; Pistidda, C.; Jepsen, J.; Tolkiehn, M.; Welter, E.; Klassen, T.; Bellosta von Colbe, J.; Dornheim, M.

    2015-06-01

    Lithium reactive hydride composite 2LiBH4 + MgH2 (Li-RHC) has been lately investigated owing to its potential as hydrogen storage medium for mobile applications. However, the main problem associated with this material is its sluggish kinetic behavior. Thus, aiming to improve the kinetic properties, in the present work the effect of the addition of Fe to Li-RHC is investigated. The addition of Fe lowers the starting decomposition temperature of Li-RHC about 30 °C and leads to a considerably faster isothermal dehydrogenation rate during the first hydrogen sorption cycle. Upon hydrogenation, MgH2 and LiBH4 are formed whereas Fe appears not to take part in any reaction. Upon the first dehydrogenation, the formation of nanocrystalline, well distributed FeB reduces the overall hydrogen storage capacity of the system. Throughout cycling, the agglomeration of FeB particles causes a kinetic deterioration. An analysis of the hydrogen kinetic mechanism during cycling shows that the hydrogenation and dehydrogenation behavior is influenced by the activity of FeB as heterogeneous nucleation center for MgB2 and its non-homogenous distribution in the Li-RHC matrix.

  13. [Vitamin A deficiency and xerophtalmia

    Science.gov (United States)

    Diniz, A da S; Santos, L M

    2000-11-01

    OBJECTIVE: To review cases of vitamin A deficiency and the effects of vitamin A supplementation on child morbidity and mortality. METHODS: Articles published in scientific journals, technical and scientific books, and also publications by international organizations were used as source of information. RESULTS: Clinical manifestations of xerophthalmia affect the retina (night blindness), the conjunctiva (conjunctival xerosis, with or without Bitot spots), and the cornea (corneal xerosis). Corneal xerosis may lead to corneal ulceration and liquefactive necrosis (keratomalacia). A priori, these signs and symptoms are the best indicators of vitamin A deficiency; they are, however, extremely rare. Laboratory indicators include Conjunctival Impression Cytology and serum retinol concentrations. The World Health Organization (WHO) recommends the use of two biological markers in order to characterize vitamin A deficiency in a given population. If only one biological marker is used, this marker has to be backed up by a set of at least four additional risk factors. Corneal xerophthalmia should be treated as a medical emergency; In the event of suspected vitamin A deficiency, a 200,000 IU vitamin A dose should be administered orally, repeating the dose after 24 hours (half the dose for infants younger than one year). Vitamin A supplementation in endemic areas may cause a 23 to 30% reduction in the mortality rate of children aged between 6 months and five years, and attenuate the severity of diarrhea. The methods for the control of vitamin A deficiency are available in the short (supplementation with megadoses), medium (food fortification), and long run (diet diversification). CONCLUSION: There is evidence of vitamin A deficiency among Brazilian children. Pediatricians must be aware of the signs and symptoms of this disease, however sporadic they might be. It is of paramount importance that vitamin A be included in public policy plans so that we can ensure the survival of

  14. Contamination Effects on Improving the Hydrogenation/Dehydrogenation Kinetics of Binary Magnesium Hydride/Titanium Carbide Systems Prepared by Reactive Ball Milling.

    Science.gov (United States)

    El-Eskandarany, M Sherif; Shaban, Ehab

    2015-10-10

    Ultrafine MgH₂ nanocrystalline powders were prepared by reactive ball milling of elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy. The as-synthesized MgH₂ was doped with previously prepared TiC nanopowders, which were contaminated with 2.4 wt. % FeCr (materials of the milling media), and then ball milled under hydrogen gas atmosphere for 50 h. The results related to the morphological examinations of the fabricated nanocomposite powders beyond the micro-and nano-levels showed excellent distributions of 5.2 wt. % TiC/4.6 wt. % FeCr dispersoids embedded into the fine host matrix of MgH₂ powders. The as-fabricated nanocomposite MgH₂/5.2 wt. % TiC/4.6 wt. % FeCr powders possessed superior hydrogenation/dehydrogenation characteristics, suggested by the low value of the activation energy (97.74 kJ/mol), and the short time required for achieving a complete absorption (6.6 min) and desorption (8.4 min) of 5.51 wt. % H₂ at a moderate temperature of 275 °C under a hydrogen gas pressure ranging from 100 mbar to 8 bar. van't Hoff approach was used to calculate the enthalpy (DH) and entropy (DS) of hydrogenation for MgH₂, which was found to be -72.74 kJ/mol and 112.79 J/mol H₂/K, respectively. Moreover, van't Hoff method was employed to calculate the DH and DS of dehydrogenation, which was found to be 76.76 kJ/mol and 119.15 J/mol H₂/K, respectively. This new nanocomposite system possessed excellent absorption/desorption cyclability of 696 complete cycles, achieved in a cyclic-life-time of 682 h.

  15. Contamination Effects on Improving the Hydrogenation/Dehydrogenation Kinetics of Binary Magnesium Hydride/Titanium Carbide Systems Prepared by Reactive Ball Milling

    Science.gov (United States)

    El-Eskandarany, M. Sherif; Shaban, Ehab

    2015-01-01

    Ultrafine MgH2 nanocrystalline powders were prepared by reactive ball milling of elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy. The as-synthesized MgH2 was doped with previously prepared TiC nanopowders, which were contaminated with 2.4 wt. % FeCr (materials of the milling media), and then ball milled under hydrogen gas atmosphere for 50 h. The results related to the morphological examinations of the fabricated nanocomposite powders beyond the micro-and nano-levels showed excellent distributions of 5.2 wt. % TiC/4.6 wt. % FeCr dispersoids embedded into the fine host matrix of MgH2 powders. The as-fabricated nanocomposite MgH2/5.2 wt. % TiC/4.6 wt. % FeCr powders possessed superior hydrogenation/dehydrogenation characteristics, suggested by the low value of the activation energy (97.74 kJ/mol), and the short time required for achieving a complete absorption (6.6 min) and desorption (8.4 min) of 5.51 wt. % H2 at a moderate temperature of 275 °C under a hydrogen gas pressure ranging from 100 mbar to 8 bar. van’t Hoff approach was used to calculate the enthalpy (∆H) and entropy (∆S) of hydrogenation for MgH2, which was found to be −72.74 kJ/mol and 112.79 J/mol H2/K, respectively. Moreover, van’t Hoff method was employed to calculate the ΔH and ΔS of dehydrogenation, which was found to be 76.76 kJ/mol and 119.15 J/mol H2/K, respectively. This new nanocomposite system possessed excellent absorption/desorption cyclability of 696 complete cycles, achieved in a cyclic-life-time of 682 h. PMID:28793606

  16. Contamination Effects on Improving the Hydrogenation/Dehydrogenation Kinetics of Binary Magnesium Hydride/Titanium Carbide Systems Prepared by Reactive Ball Milling

    Directory of Open Access Journals (Sweden)

    M. Sherif El-Eskandarany

    2015-10-01

    Full Text Available Ultrafine MgH2 nanocrystalline powders were prepared by reactive ball milling of elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy. The as-synthesized MgH2 was doped with previously prepared TiC nanopowders, which were contaminated with 2.4 wt. % FeCr (materials of the milling media, and then ball milled under hydrogen gas atmosphere for 50 h. The results related to the morphological examinations of the fabricated nanocomposite powders beyond the micro-and nano-levels showed excellent distributions of 5.2 wt. % TiC/4.6 wt. % FeCr dispersoids embedded into the fine host matrix of MgH2 powders. The as-fabricated nanocomposite MgH2/5.2 wt. % TiC/4.6 wt. % FeCr powders possessed superior hydrogenation/dehydrogenation characteristics, suggested by the low value of the activation energy (97.74 kJ/mol, and the short time required for achieving a complete absorption (6.6 min and desorption (8.4 min of 5.51 wt. % H2 at a moderate temperature of 275 C under a hydrogen gas pressure ranging from 100 mbar to 8 bar. van’t Hoff approach was used to calculate the enthalpy (DH and entropy (DS of hydrogenation for MgH2, which was found to be 72.74 kJ/mol and 112.79 J/mol H2/K, respectively. Moreover, van’t Hoff method was employed to calculate the DH and DS of dehydrogenation, which was found to be 76.76 kJ/mol and 119.15 J/mol H2/K, respectively. This new nanocomposite system possessed excellent absorption/desorption cyclability of 696 complete cycles, achieved in a cyclic-life-time of 682 h.

  17. [Phosphate metabolism and iron deficiency].

    Science.gov (United States)

    Yokoyama, Keitaro

    2016-02-01

    Autosomal dominant hypophosphatemic rickets(ADHR)is caused by gain-of-function mutations in FGF23 that prevent its proteolytic cleavage. Fibroblast growth factor 23(FGF23)is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. Low iron status plays a role in the pathophysiology of ADHR. Iron deficiency is an environmental trigger that stimulates FGF23 expression and hypophosphatemia in ADHR. It was reported that FGF23 elevation in patients with CKD, who are often iron deficient. In patients with nondialysis-dependent CKD, treatment with ferric citrate hydrate resulted in significant reductions in serum phosphate and FGF23.

  18. Iron deficiency in the tropics.

    Science.gov (United States)

    Fleming, A F

    1982-06-01

    Iron in food is classified as belonging to the haem pool, the nonhaem pool, and extraneous sources. Haem iron is derived from vegetable and animal sources with varying bioavailability. Hookworm infestation of the intestinal tract affects 450 million people in the tropics. Schistosoma mansoni caused blood loss in 7 Egyptian patients of 7.5- 25.9 ml/day which is equivalent to a daily loss of iron of .6-7.3 mg daily urinary loss of iron in 9 Egyptian patients. Trichuris trichiura infestation by whipworm is widespread in children with blood loss of 5 ml/day/worm. The etiology of anemia in children besides iron deficiency includes malaria, bacterial or viral infections, folate deficiency and sickle-cell disease. Severe infections cause profound iron-deficiency anemia in children in central American and Malaysia. Plasmodium falciparum malaria-induced anaemia in tropical Africa lowers the mean haemoglobin concentration in the population by 2 g/dI, causing profound anaemia in some. The increased risk of premature delivery, low birthweight, fetal abnormalities, and fetal death is directly related to the degree of maternal anemia. Perinatal mortality was reduced from 38 to 4% in treated anemic mothers. Mental performance was significantly lower in anemic school children and improved after they received iron. Supplements of iron, soy-protein, calcium, and vitamins given to villagers with widespread malnutrition, iron deficiency, and hookworm infestation in Colombia reduced enteric infections in children. Severe iron-deficiency anemia was treated in adults in northern Nigeria by daily in Ferastral 10 ml, which is equivalent to 500 mg of iron per day. Choloroquine, folic acid, rephenium hydroxynaphthoate, and tetrachlorethylene treat adults with severe iron deficiency from hookworm infestation in rural tropical Africa. Blood transfusion is indicated if the patient is dying of anaemia or is pregnant with a haemoglobin concentration 6 gm/dl. In South East Asia, mg per day

  19. Differential diagnosis of iron deficiency

    OpenAIRE

    2010-01-01

    A deficiência de ferro é considerada a patologia hematológica mais prevalente no homem. Assim, é fundamental a adequada identificação de suas causas, bem como a diferenciação com outras patologias distintas para adequada abordagem da deficiência de ferro. Neste artigo são brevemente descritas outras condições que podem cursar com anemia microcítica, tais como: talassemias, anemia de doença crônica, anemia sideroblástica e envenenamento por chumbo, patologias estas que devem ser afastadas dura...

  20. Primary Carnitine (OCTN2) Deficiency Without Neonatal Carnitine Deficiency

    NARCIS (Netherlands)

    Boer, L. de; Kluijtmans, L.A.J.; Morava, E.

    2013-01-01

    Although the diagnosis of a primary carnitine deficiency is usually based on a very low level of free and total carnitine (free carnitine: 1-5 muM, normal 20-55 muM) (Longo et al. 2006), we detected a patient via newborn screening with a total carnitine level 67 % of the normal value. At the age of

  1. Genetics Home Reference: CLPB deficiency

    Science.gov (United States)

    ... Med Genet. 2015 May;52(5):303-11. doi: 10.1136/jmedgenet-2014-102952. Citation on PubMed GeneReview: CLPB Deficiency Kanabus M, Shahni R, Saldanha JW, Murphy E, ... 2015 Mar;38(2):211-9. doi: 10.1007/s10545-015-9813-0. Citation on ...

  2. Educational paper: Primary antibody deficiencies

    NARCIS (Netherlands)

    G.J.A. Driessen (Gertjan); M. van der Burg (Mirjam)

    2011-01-01

    textabstractPrimary antibody deficiencies (PADs) are the most common primary immunodeficiencies and are characterized by a defect in the production of normal amounts of antigen-specific antibodies. PADs represent a heterogeneous spectrum of conditions, ranging from often asymptomatic selective IgA a

  3. Deficiencies in Indian Joint Operations

    Science.gov (United States)

    2016-05-26

    compartmentalization, and bureaucratic inefficiencies. Indian regional hegemony in South Asia faces significant risks without critically needed reforms to enable...illustrates India’s limited capability to conduct joint operations. Specifically, India demonstrated critical planning deficiencies in joint...society, and this has influenced its understanding of theory and concepts, and its application of those ideas in the development of its own joint

  4. Dopamine beta-hydroxylase deficiency

    Directory of Open Access Journals (Sweden)

    Senard Jean-Michel

    2006-03-01

    Full Text Available Abstract Dopamine beta-hydroxylase (DβH deficiency is a very rare form of primary autonomic failure characterized by a complete absence of noradrenaline and adrenaline in plasma together with increased dopamine plasma levels. The prevalence of DβH deficiency is unknown. Only a limited number of cases with this disease have been reported. DβH deficiency is mainly characterized by cardiovascular disorders and severe orthostatic hypotension. First symptoms often start during a complicated perinatal period with hypotension, muscle hypotonia, hypothermia and hypoglycemia. Children with DβH deficiency exhibit reduced ability to exercise because of blood pressure inadaptation with exertion and syncope. Symptoms usually worsen progressively during late adolescence and early adulthood with severe orthostatic hypotension, eyelid ptosis, nasal stuffiness and sexual disorders. Limitation in standing tolerance, limited ability to exercise and traumatic morbidity related to falls and syncope may represent later evolution. The syndrome is caused by heterogeneous molecular alterations of the DBH gene and is inherited in an autosomal recessive manner. Restoration of plasma noradrenaline to the normal range can be achieved by therapy with the synthetic precursor of noradrenaline, L-threo-dihydroxyphenylserine (DOPS. Oral administration of 100 to 500 mg DOPS, twice or three times daily, increases blood pressure and reverses the orthostatic intolerance.

  5. Deferasirox in pyruvate kinase deficiency

    OpenAIRE

    Deeren, Dries

    2008-01-01

    Deferasirox in pyruvate kinase deficiency phone: +32-51-237437 (Deeren, Dries) (Deeren, Dries) Department of Haematology, Heilig-Hartziekenhuis Roeselare-Menen vzw - Wilgenstraat 2 - B-8800 - Roeselare - BELGIUM (Deeren, Dries) BELGIUM Registration: 2008-09-10 Received: 2008-09-05 Accepted: 2008-09-10 ePublished: 2008-09-23

  6. Epigenetic Deficiencies and Replicative Stress

    DEFF Research Database (Denmark)

    Shoaib, Muhammad; Sørensen, Claus Storgaard

    2015-01-01

    Cancer cell-specific synthetic lethal interactions entail promising therapeutic possibilities. In this issue of Cancer Cell, Pfister et al. describe a synthetic lethal interaction where cancer cells deficient in H3K36me3 owing to SETD2 loss-of-function mutation are strongly sensitized to inhibiti...

  7. Management of Iron Deficiency Anemia

    Science.gov (United States)

    Jimenez, Kristine; Kulnigg-Dabsch, Stefanie

    2015-01-01

    Anemia affects one-fourth of the world’s population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blood transfusions. Treatment options include oral and intravenous iron therapy; however, the efficacy of oral iron is limited in certain gastrointestinal conditions, such as inflammatory bowel disease, celiac disease, and autoimmune gastritis. This article provides a critical summary of the diagnosis and treatment of iron deficiency anemia. In addition, it includes a management algorithm that can help the clinician determine which patients are in need of further gastrointestinal evaluation. This facilitates the identification and treatment of the underlying condition and avoids the unnecessary use of invasive methods and their associated risks. PMID:27099596

  8. Congenital β-lipoprotein deficiency

    NARCIS (Netherlands)

    Buchem, F.S.P. van; Pol, G.; Gier, J. de; Böttcher, C.J.F.; Pries, C.

    1966-01-01

    There are several degrees of β-lipoprotein deficiency. If there is no β-lipoprotein present, or if there are only traces of it, the Bassen-Kornzweig syndrome develops. A constant feature of this syndrome is disturbed fat absorption with accumulation of fat in the epithelium of intestinal mucosa and

  9. The effect of mixed HCl-KCl competitive adsorbate on Pt adsorption and catalytic properties of Pt-Sn/Al2O3 catalysts in propane dehydrogenation

    Science.gov (United States)

    Zangeneh, Farnaz Tahriri; Taeb, Abbas; Gholivand, Khodayar; Sahebdelfar, Saeed

    2015-12-01

    The effect of competitive adsorbate concentration and combination on the adsorption of H2PtCl6 onto γ-Al2O3 in the preparation and performance of PtSnK/γ-Al2O3 catalyst for propane dehydrogenation was investigated. The catalysts were prepared by sequential impregnation of Sn and Pt precursors. The effect of competitor concentration on Pt adsorption was studied by using hydrochloric acid (0.1-0.3 M) and the effect of pH was studied by using KCl/HCl mixtures at constant (0.1 M) total chloride ion concentration. The catalysts were characterized by nitrogen adsorption/desorption, XRD, XRF, SEM and CO chemisorption. The catalytic performance tests were carried out in a fixed-bed quartz reactor under kinetic controlled condition for proper catalyst screening. It was found that the corrosive competitor HCl could be partially substituted with KCl without appreciable impact on catalyst performance with the advantage of lower acid attack on the support and reduced leaching of the deposited tin. A model based on initial concentration and uptake of the adsorbates was developed to obtain the adsorption parameters. Values of 890 μmol/g and 600 lit/mol were obtained for adsorption site concentration of the tin-impregnated support and equilibrium constant for Pt adsorption, respectively, for HCl concentration range of 0.1-0.3 M.

  10. A study by electrical conductivity measurements of the semiconductive and redox properties of Nb-doped NiO catalysts in correlation with the oxidative dehydrogenation of ethane.

    Science.gov (United States)

    Popescu, Ionel; Skoufa, Zinovia; Heracleous, Eleni; Lemonidou, Angeliki; Marcu, Ioan-Cezar

    2015-03-28

    Nb-doped nickel oxides with Nb contents in the range from 1 to 20% and, for comparison, pure NiO, were characterized using in situ electrical conductivity measurements in correlation with their catalytic performances for the oxidative dehydrogenation (ODH) of ethane into ethylene. Their electrical conductivity was studied as a function of temperature and oxygen partial pressure and was followed with time during sequential exposures to air, ethane-air mixture (reaction mixture) and pure ethane in conditions similar to those of catalysis. All the oxides were p-type semiconductors under air. Their electrical conductivity in the reaction temperature range decreased in the following order: NiO > Nb(1)NiO > Nb(5)NiO > Nb(10)NiO > Nb(15)NiO > Nb(20)NiO. This correlates well with the catalytic activity expressed as the intrinsic rate of ethane consumption. All the catalysts were partially reduced under the reaction mixture in the reaction temperature range, an inverse correlation between their conductivity in these conditions and the ODH selectivity being observed. The ODH reaction of ethane takes place via a heterogeneous redox mechanism involving the surface lattice O(-) species.

  11. Deactivation of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the reaction of oxidative ethane dehydrogenation

    Science.gov (United States)

    Mishanin, I. I.; Kalenchuk, A. N.; Maslakov, K. I.; Lunin, V. V.; Koklin, A. E.; Finashina, E. D.; Bogdan, V. I.

    2016-06-01

    The operational stability of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the oxidative dehydrogenation of ethane (ratio of C2H6: O2 = 3: 1) is studied in a flow reactor at temperatures of 340-400°C, a pressure of 1 atm, and a WHSV of the feed mixture of 800 h-1. It is found that the selectivity toward ethylene is 98% at 340°C, but the conversion of ethane at this temperature is only 6%; when the temperature is raised to 400°C, the conversion of ethane is increased to 37%, while the selectivity toward ethylene is reduced to 85%. Using physical and chemical means (XPS, SEM), it is found that the lack of oxidant in the reaction mixture leads to irreversible changes in the catalyst, i.e., reduced selectivity and activity. Raising the reaction temperature to 400°C allows the reduction of tellurium by ethane, from the +6 oxidation state to the zerovalent state, with its subsequent sublimation and the destruction of the catalytically active and selective phase; in its characteristics, the catalyst becomes similar to the Mo-V-Nb-O system containing no tellurium.

  12. Photofragmentation of the closo-carboranes part II: VUV assisted dehydrogenation in the closo-carboranes and semiconducting B10C2H(x) films.

    Science.gov (United States)

    Rühl, Eckart; Riehs, Norman F; Behera, Swayambhu; Wilks, Justin; Liu, Jing; Jochims, H-W; Caruso, Anthony N; Boag, Neil M; Kelber, Jeffry A; Dowben, Peter A

    2010-07-15

    The dehydrogenation of semiconducting boron carbide (B(10)C(2)H(x)) films as well as the three closo-carborane isomers of dicarbadodecaborane (C(2)B(10)H(12)) and two isomers of the corresponding closo-phosphacarborane (PCB(10)H(11)) all appear to be very similar. Photoionization mass spectrometry studies at near-threshold gas phase photoionization indicate that the preferred pathway for dissociation of the parent cation species (C(2)B(10)H(10)(+) or PCB(10)H(9)(+)) is, in all cases, the loss of H(2). Ab initio density functional theory (DFT) calculations indicate that energetically preferred sites for exopolyhedral hydrogen (B-H) bond dissociation are in all cases at B atoms opposite the C atoms in the parent cage molecule. The site of photodissociation of hydrogen from semiconducting boron carbide (B(10)C(2)H(x)) films, fabricated by plasma-enhanced chemical vapor deposition, is a cage boron atom that can bond to nitrogen upon exposure to VUV light in the presence of NH(3). Shifts in core level binding energies due to nitrogen bond formation indicate that B-N bond formation occurs only at B atoms bound to other boron atoms (B-B sites) and not at B-C sites or at C sites, in agreement with gas phase results.

  13. One-pot synthesis of core-shell Cu@SiO2 nanospheres and their catalysis for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

    Science.gov (United States)

    Yao, Qilu; Lu, Zhang-Hui; Zhang, Zhujun; Chen, Xiangshu; Lan, Yaqian

    2014-12-01

    Ultrafine copper nanoparticles (Cu NPs) within porous silica nanospheres (Cu@SiO2) were prepared via a simple one-pot synthetic route in a reverse micelle system and characterized by SEM, TEM, EDX, XRD, N2 adsorption-desorption, CO-TPD, XPS, and ICP methods. The characterized results show that ultrafine Cu NPs with diameter of around 2 nm are effectively embedded in the center of well-proportioned spherical SiO2 NPs of about 25 nm in diameter. Compared to commercial SiO2 supported Cu NPs, SiO2 nanospheres supported Cu NPs, and free Cu NPs, the synthesized core-shell nanospheres Cu@SiO2 exhibit a superior catalytic activity for the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3) and hydrazine borane (HB, N2H4BH3) under ambient atmosphere at room temperature. The turnover frequencies (TOF) for the hydrolysis of AB and HB in the presence of Cu@SiO2 nanospheres were measured to be 3.24 and 7.58 mol H2 (mol Cu min)-1, respectively, relatively high values for Cu nanocatalysts in the same reaction. In addition, the recycle tests show that the Cu@SiO2 nanospheres are still highly active in the hydrolysis of AB and HB, preserving 90 and 85% of their initial catalytic activity even after ten recycles, respectively.

  14. Effect of CO{sub 2}-admixture on the catalytic performance of Ni-Nb-M-O catalysts in oxidative dehydrogenation of ethane to ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, A.; Kalevaru, V.N.; Martin, A. [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse e.V.; Hari Kumar, A. Sri; Lingaiah, N.; Prasad, P.S. Sai [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2012-07-01

    In this work, we report the synthesis, characterization and application of Ni-Nb-M-O catalysts with different promoters (M = Cr, Mo, W) for the oxidative dehydrogenation (ODH) of ethane to ethylene. Ni:Nb:M ratio was kept at 1:0.176:0.1 (atomic ratio). The catalysts were calcined at 450 C/5h/air. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 300 to 450 C, with a fixed W/F (1.02 g/cm{sup 3} . s{sup -1}) but with changing mole ratios of C{sub 2}H{sub 6}:O{sub 2}:CO{sub 2}:N{sub 2} (1:0-1.4:1.4-0:2). The product analysis was made off-line using GC equipped with FID. It is evident that the CO{sub 2}-admixture to the reactant feed caused a slight decrease in the conversion of ethane but considerably improved the selectivity of ethylene. Among the three promoters of the same group applied, Cr exhibited superior performance compared to other two. This means increase in d-character of transition metal (i.e. from 3d to 5d) has shown an adverse effect on the conversion of ethane and selectivity of ethylene. (orig.)

  15. Preparation of Highly Active Pt-K/γ-AI203 Catalyst for 0-Phenylphenol Synthesis from 0-Cyclohexenyl-cyclohexanone Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    DING Jie-lian; LIN Ling; XU Jian-dong; ZENG Chong-yu

    2008-01-01

    0.5%Pt-K/y-Al2O3 catalysts for the synthesis of 0-phenylphenol(OPP) from 0-cyclohexenyl-cyciohexanone (dimer) dehydrogenation were prepared by means of a two subsequent impregnation method.The effects of catalyst preparation parameters,such as K promoters,calcination,and reduction conditions,were investigated.The results showed that the addition of K2SO4 to Pt/y-Al2O3 catalyst notably promoted the selectivity of OPP,and its optimum content was found to be 6% in mass fraction.The higher activity was obtained when Pt/y-Al2O3 catalyst was calcined in nitrogen atmosphere at 400-500℃ and then reduced at the same temperature for 3 h in hydrogen atmosphere.The conversion of the dimer and the selectivity of OPP were always above 99% and 90%,respectively,over 0.5%Pt-6% K2SO4/γ-Al2O3 catalyst during the pilot scale test of 8000 h.

  16. Effect of gallium,aluminium,and chromium on silica supported V-Mg-O catalysts during oxidative dehydrogenation of propane:Kinetic study

    Institute of Scientific and Technical Information of China (English)

    B.Ravi Kumar; Rajeev Kumar

    2008-01-01

    The oxidative dehydrogenation(ODH)of propane was conducted on gallium,aluminum.and chromium doped Si30VMgO catalysts.On doping,the concentrations of the phases responsible for the activity and selectivity increased in their concentrations.The reaction studies were conducted in a tubular steel reactor at temperatures of 753,783,813.and 843 K and atmospheric pressure.The total flow rates of the feed were chosen as 30,40,50,and 60 ml/min.The propane to oxygen ratios were chosen at 1:1,2:1,and 3:1,respectively.The effect of various dopants on the activity and selectivity of the catalysts was studied.Deactivation studies were conducted over all the catalysts.The kinetic data were analyzed in terms of power law models and Langmuir-Hinshelwood(LH)models.The kinetic data results were analyzed by comparing the effect of dopants.Statistical model discrimination was done for the proposed models.AIC and BIC criteria were used for discrimination of the models.

  17. V{sub 2}O{sub 5}-ZrO{sub 2} catalysts for the oxidative dehydrogenation of propane - influence of the niobium oxide doping

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, S.; Hallmeier, K.H.; Wendt, G. [Leipzig Univ. (Germany). Fakultaet fuer Chemie und Mineralogie; Lippold, G. [Leipzig Univ. (Germany). Fakultaet fuer Physik und Geowissenschaften

    1998-12-31

    The oxidative dehydrogenation (ODH) of light alkanes is an alternative way for the production of olefins. A wide variety of catalytic systems has been investigated. Vanadium oxide based catalysts were described in the literature as effective catalysts for the ODH of propane. The catalytic activity and selectivity depend on the kind of support material, the kind of dopants and the formation of complex metal oxide phases. In recent papers it was claimed that both orthovanadate and/or pyrovanadate species are selective for the ODH of propane. Niobia based materials were investigated as catalysts for acidic and selective oxidation type reactions. In the ODH of propane niobia exhibited a high selectivity to propene but the conversion of propane was low. V{sub 2}O{sub 5}-Nb{sub 2}O{sub 5} catalysts proved to be catalytically active and selective and showed no formation of oxygenates. In the present study the influence of the niobia dopant of the catalytic properties of V{sub 2}O{sub 5}-ZrO{sub 2} catalysts in the ODH of propane was examined. The structural and textural properties of the catalysts were investigated using several methods. (orig.)

  18. Catalytic amine-borane dehydrogenation by a PCP-pincer palladium complex: a combined experimental and DFT analysis of the reaction mechanism.

    Science.gov (United States)

    Rossin, Andrea; Bottari, Giovanni; Lozano-Vila, Ana M; Paneque, Margarita; Peruzzini, Maurizio; Rossi, Andrea; Zanobini, Fabrizio

    2013-03-14

    Catalytic dehydrogenation of ammonia-borane (NH(3)·BH(3), AB) and dimethylamine borane (NHMe(2)·BH(3), DMAB) by the Pd(II) complex [((tBu)PCP)Pd(H(2)O)]PF(6) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] leads to oligomerization and formation of spent fuels of general formula cyclo-[BH(2)-NR(2)](n) (n = 2,3; R = H, Me) as reaction byproducts, while one equivalent of H(2) is released per amine-borane equivalent. The processes were followed through multinuclear ((31)P, (1)H, (11)B) variable temperature NMR spectroscopy; kinetic measurements on the hydrogen production rate and the relative rate constants were also carried out. One non-hydridic intermediate could be detected at low temperature, whose chemical nature was explored through a DFT modeling of the reaction mechanism, at the M06//6-31+G(d,p) computational level. The computational output was of help to propose a reliable mechanistic picture of the process.

  19. Mechanical and Thermal Dehydrogenation of the Mechano-Chemically Synthesized Calcium Alanate (Ca(AlH42 and Lithium Chloride (LiCl Composite

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-06-01

    Full Text Available LiAlH4 and CaCl2 were employed for mechano-chemical activation synthesis (MCAS of Ca(AlH42 and LiCl hydride composite. After short ball milling time, their X-ray diffraction (XRD peaks are clearly observed. After ball milling for a longer duration than 0.5 h, the CaAlH5 diffraction peaks are observed which indicates that Ca(AlH42 starts decomposing during ball milling into CaAlH5+Al+1.5H2. It is estimated that less than 1 wt % H2 was mechanically dehydrogenated in association with decomposition reaction. After 2.5 h of ball milling, no Ca(AlH42 diffraction peaks were observed on XRD patterns which suggests that Ca(AlH42 was decomposed. Thermal behavior of ball milled powders, which was investigated by thermal gravimetric analysis (TGA and differential scanning calorimetry (DSC, indicates that a certain fraction of Ca(AlH42 could have been disordered/amorphized during ball milling being undetectable by XRD. The apparent activation energy for the decomposition of Ca(AlH42 and CaAlH5 equals 135 kJ/mol and 183 kJ/mol, respectively.

  20. Catalytic properties of the VO x /Ce0.46Zr0.54O2 oxide system in the oxidative dehydrogenation of propane

    Science.gov (United States)

    Turakulova, A. O.; Kharlanov, A. N.; Levanov, A. V.; Isaikina, O. Ya.; Lunin, V. V.

    2017-01-01

    Ce0.46Zr0.54O2 solid solution prepared using a cellulose template was employed as a carrier for vanadium catalysts of the oxidative dehydrogenation of propane. The properties of VO x /Ce0.46Zr0.54O2 catalyst (5 wt % vanadium) are compared with the properties of the neat support. The carrier and catalyst are studied by means of BET, SEM, DTA, XRD, and Raman spectroscopy. It is shown that the CeVO4 phase responsible for the ODH process is formed upon interaction between vanadate ions and cerium ions on the surface of the solid solution. The catalytic properties of the catalyst and the support are studied in the propane oxidation reaction at temperatures of 450 and 500°C with pulse feeding of the reagent. It is found that the complete oxidation of propane occurs on the support with formation of CO2 and H2O. Three products (propene, CO2, and H2O) form in the presence of the vanadium catalyst. It is suggested that there are two types of catalytic centers on the catalyst's surface. It is concluded that the centers responsible for the complete oxidation of propane are concentrated mainly on the carrier, while the centers responsible for propane ODH are on the CeVO4.