نتایج جستجو برای: shape selective catalysts

تعداد نتایج: 415754  

2010
Jurriaan Beckers Gadi Rothenberg

This Perspective covers sustainable oxidation processes using doped cerias, ceria-supported catalysts and ceria-based mixed oxides. Firstly, we consider the general properties of ceria-based catalysts. We outline the advantages of the ceria redox cycle, and explain the dynamic behaviour of these catalysts in the presence of metal additives and dopants. We then review three types of catalytic ox...

2009
Graham J. Hutchings

Heterogeneous catalysis plays a key role in the manufacture of essential products in key areas of agriculture and pharmaceuticals, but also in the production of polymers and numerous essential materials. Our understanding of heterogeneous catalysts is advancing rapidly, especially by using the latest characterisation methods on these relatively complex effect materials. At the heart of these ca...

Journal: :iranian journal of catalysis 2015
najme kalvari janaki razieh fazaeli hamid aliyan

a series of fe3o4 supported on mesoporous fdu-12 silica systems were prepared by the hydrothermal conditions. the surface properties of the functionalized catalyst were analyzed by a series of characterization techniques like ftir, xrd, n2 adsorption–desorption and tem. xrd and adsorption–desorption analysis shows that the mesostructure of fdu silica remains intact after fe3o4 modifications, wh...

2005

The Society of Automotive Engineers’ (Sm) Detroit World Congress in the Cob0 Center (5th-8th March) was a great success, with some 50,000 delegates, and about 1300 technical presentations. There were many well-attended sessions on the control of engine exhaust emissions, and this selective review focuses on papers concerned with platinum group metal @gm) catalysts. Platinum oxidation catalysts ...

2017
Chang Hyuck Choi Won Seok Choi Olga Kasian Anna K Mechler Moulay Tahar Sougrati Sebastian Brüller Kara Strickland Qingying Jia Sanjeev Mukerjee Karl J J Mayrhofer Frédéric Jaouen

Fe-N-C catalysts with high O2 reduction performance are crucial for displacing Pt in low-temperature fuel cells. However, insufficient understanding of which reaction steps are catalyzed by what sites limits their progress. The nature of sites were investigated that are active toward H2 O2 reduction, a key intermediate during indirect O2 reduction and a source of deactivation in fuel cells. Cat...

Journal: :Organometallics 2013
Koji Endo Myles B Herbert Robert H Grubbs

A series of ruthenium catalysts bearing five-membered chelating NHC architectures that exhibit very high Z-selectivity in a variety of metathesis reactions have recently been reported. It was envisioned that catalysts possessing sixmembered chelates could similarly exhibit high Z-selectivity and address limitations of this methodology. We thus prepared a number of new catalysts and systematical...

Journal: :Acta chimica Slovenica 2010
Sameh M K Aboul-Fotouh Marwa M I Hassan

This paper deals with maximizing dimethyl ether (DME) production from methanol due to its industrial importance as a future diesel fuel. The high acidity and the micro-porous structure of the catalysts encouraged this reaction. Catalysts containg 6% CuO supported on H-ZSM-5 and H-MOR zeolites give high activities for DME production. The 6% CuO/HMOR is more selective for DME production, while th...

2012
Phillip A. Lichtor Scott J. Miller

Selectivity in the catalytic functionalization of complex molecules is a major challenge in chemical synthesis. The problem is magnified when there are several possible stereochemical outcomes and when similar functional groups occur repeatedly within the same molecule. Selective polyene oxidation provides an archetypical example of this challenge. Historically, enzymatic catalysis has provided...

2017
Marianna Casavola Jingxiu Xie Johannes D. Meeldijk Nynke A. Krans Andrey Goryachev Jan P. Hofmann A. Iulian Dugulan Krijn P. de Jong

Colloidal synthesis routes have been recently used to fabricate heterogeneous catalysts with more controllable and homogeneous properties. Herein a method was developed to modify the surface composition of colloidal nanocrystal catalysts and to purposely introduce specific atoms via ligands and change the catalyst reactivity. Organic ligands adsorbed on the surface of iron oxide catalysts were ...

2003
G. J. Hutchings J. A. Lopez-Sanchez J. K. Bartley J. M. Webster A. Burrows C. J. Kiely A. F. Carley C. Rhodes M. Hävecker A. Knop-Gericke R. W. Mayer R. Schlögl J. C. Volta M. Poliakoff

A new preparative route for vanadium phosphate catalysts is described using supercritical CO2 as an antisolvent. The amorphous microspheroidal VPO produced is shown to be more active than comparable crystalline VPO catalysts for the selective oxidation of n-butane to maleic anhydride and, furthermore, does not require an extensive pre-treatment or activation period to establish full catalytic a...

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