نتایج جستجو برای: Pt–based catalysts

تعداد نتایج: 32940  

2014
Qing Li Gang Wu David A. Cullen Karren L. More Nathan H. Mack Hoon T. Chung Piotr Zelenay

Increased oxygen reduction reaction (ORR) kinetics, improved CO tolerance, and more efficient water and heat management represent significant advantages that high-temperature polymer electrolyte fuel cells (HT-PEFCs) operating with a phosphoric acid-doped polybenzimidazole (PBI) membrane offer over traditional Nafion-based, low-temperature PEFCs. However, before such HT-PEFCs become viable, the...

2017
Zhi-you Zhou Shaowei Chen

Low temperature fuel cells are a promising clean energy source, which can directly convert the chemical energy stored in hydrogen and small organic molecules (e.g., methanol, ethanol, and formic acid) into electrical energy with high efficiency, and thus find extensive applications in, for instance, automobiles and portable electronic devices. However, the commercialization of fuel cells is ser...

2011
Jana Schäferhans Santiago Gómez-Quero Daria V Andreeva Gadi Rothenberg

The importance of solid catalysts for converting petroand bulk chemicals is reflected in the sheer magnitude of their market size: catalysts sales topped nine billion dollars in 2009. This large value mirrors also the increasing academic interest in heterogeneous catalysis research. As far as bulk chemicals (such as ethene, propene, and their derivatives) are concerned, there is a strong demand...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - پژوهشکده علوم 1388

heteropoly acids (hpa) and their salts have advantages as catalysts which make them both economically and environmentally attractive, strong br?nsted acidity, exhibiting fast reversible multi-electron redox transformations under rather mild conditions, very high solubility in polar solvents, fairly high thermal stability in the solid states, and efficient oxidizing ability, so that they are imp...

Journal: :polyolefins journal 0
natalya n. chumachenko boreskov institute of catalysis, siberian branch, russian academy of sciences, prospect akademika lavrentieva 5, novosibirsk 630090 , russian federation vladimir a. zakharov boreskov institute of catalysis, siberian branch, russian academy of sciences, prospect akademika lavrentieva 5, novosibirsk 630090 , russian federation sergey a. sergeev boreskov institute of catalysis, siberian branch, russian academy of sciences, prospect akademika lavrentieva 5, novosibirsk 630090 , russian federation svetlana v. cherepanova boreskov institute of catalysis, siberian branch, russian academy of sciences, prospect akademika lavrentieva 5, novosibirsk 630090 , russian federation

supported catalysts synthesized via the interaction of mg(oet)2 with ticl4 in the presence or absence of an internal stereoregulating donor (di-n-butyl phthalate), with different solvents (chlorobenzene, n-undecane, n-heptane) at different titanation temperatures have been studied by a set of physicochemical methods. data on the chemical composition, x-ray structure and pore structure of these ...

Journal: :journal of the iranian chemical research 0
sedigheh vaezifar department of chemistry, university of isfahan, isfahan 81746-73441, iran fadak chemical company, isfahan science and technology town (istt), isfahan, iran hossein faghihian department of chemistry, university of isfahan, isfahan 81746-73441, iran mehdi kamali central laboratory, faculty of modern sciences & technologies, university of isfahan, isfahan 81746-73441, iran

in this research different types of al2o3 were used as supports to prepare catalysts for dehydrogenation of isobutane to isobutene. these supports were al2o3 from merck, axen and gamma al2o3 synthesized from al(oh)3. sn/pt/al2o3 catalysts were prepared by sequential impregnation, at first pt and then sn was deposited. characterization of catalysts was performed by x-ray powder diffraction (xrd)...

Journal: :iranian journal of chemistry and chemical engineering (ijcce) 2009
sedigheh vaezifar hossein faghihian mahdi kamali

in this research na-y was synthesized by hydrothermal method and used as support for preparation of sn/pt/na-y catalysts using two different tin precursors, bu3sn(cl) and sncl2.2h2o, by sequential impregnation, in which the pt  was deposited first and in the next step sn was deposited. the catalysts were characterized by h2 chemisorption, transmission electron microscopy (tem), scanning electro...

Journal: :iranian journal of chemistry and chemical engineering (ijcce) 2008
layla abadian azim malekzadeh abbas ali khodadadi yadollah mortazavi

catalysts with the formula of laco(1+x)o(3+δ), where 0 ≤ x ≤ 1, were studied for oxidation of co and c2h6 in a synthetic exhaust gas, comprising 6.0 % co and 0.2 % c2h6 in ar. ethane was selected as a model for hydrocarbons in the exhaust gas. the performance of catalysts is correlated to their properties, particularly their redox in oxidizing and reducing atmospheres. xrd patterns show perovsk...

Journal: :polyolefins journal 1999
giovanni ricci giuseppe leone

the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

Journal: :polyolefins journal 2015
helmut g. alt

eethylene polymerization catalysts became available in an enormous variety. the challenge in this research is to find catalysts that are able to connect ethylene molecules in such a way that not only linear chains are produced but variations like branched materials that possess very interesting mechanical properties like linear low density polyethylene (lldpe). in this contribution, three diffe...

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