نتایج جستجو برای: catalysts

تعداد نتایج: 32940  

Journal: :Physical chemistry chemical physics : PCCP 2014
Daojian Cheng Xiangguo Qiu Haiyan Yu

Despite remarkable efforts have been put into the field of Pt-shelled catalysts containing an atomically thin Pt surface layer for the oxygen reduction reaction (ORR) in the last decade, further development of new Pt-shelled catalysts is still necessary. Here, a new set of Pt-shelled catalysts by subsurface alloying with early transition metals such as Mn and Fe is predicted to be a good candid...

2015
Zheng Cheng Rendang Yang Bin Wang Fei Yang

Heterogeneous Fe-Mn/sepiolite catalysts were prepared by the coprecipitation method, followed by heat treatment. The catalysts were characterized by several techniques; analysis by X-ray fluorescence (XRF) and scanning electron microscopy (SEM) confirmed the existence of fine Fe and Mn particles in the catalysts. Compared to natural sepiolite, the specific surface area of the Fe-Mn/sepiolite ca...

2016
Jose A Rodriguez

The water-gas shift reaction (WGS: CO + H2O  H2 + CO2) is a critical process in providing pure hydrogen for fuel cells and other applications. Improved air-tolerant, cost-effective WGS catalysts for lower temperature processing are needed. Ceria-, titaniaand molybdena-based catalysts are expected to be the next generation of WGS catalysts for industrial applications. The design and optimizatio...

Journal: :Journal of the American Chemical Society 2015
Keary M Engle Gang Lu Shao-Xiong Luo Lawrence M Henling Michael K Takase Peng Liu K N Houk Robert H Grubbs

A series of second-generation ruthenium olefin metathesis catalysts was investigated using a combination of reaction kinetics, X-ray crystallography, NMR spectroscopy, and DFT calculations in order to determine the relationship between the structure of the chelating o-alkoxybenzylidene and the observed initiation rate. Included in this series were previously reported catalysts containing a vari...

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...

Journal: :Angewandte Chemie 2017
Mark C Lipke Allegra L Liberman-Martin T Don Tilley

Hydrosilation reactions represent an important class of chemical transformations and there has been considerable recent interest in expanding the scope of these reactions by developing new catalysts. A major theme to emerge from these investigations is the development of catalysts with electrophilic character that transfer electrophilicity to silicon by Si-H activation. This type of mechanism h...

2014
Graham E. Dobereiner Gulin Erdogan Casey R. Larsen Douglas B. Grotjahn Richard R. Schrock

A tandem catalytic reaction has been developed as part of a process to discover tungsten-based olefin metathesis catalysts that have a strong preference for terminal olefins over cis or trans internal isomers in olefin metathesis. This tandem isomerization/terminal olefin metathesis reaction (ISOMET) converts Cn trans internal olefins into C2n−2 cis olefins and ethylene. This reaction is made p...

2008
B. Zeifert J. S. Blásquez

Raney catalysts were prepared by a combination of mechanical alloying and leaching as an alternative in the synthesis of Raney-Nickel catalysts. Binary Al-Ni and ternary Al-Ni-Fe alloys with nominal compositions Al65Ni35, Al75Ni25, Al65Ni30Fe5, Al75Ni20Fe5 (in atomic percent), were processed from pure elemental powders; they consisted mainly of the intermetallic B2 AlNi phase. Aluminum was sele...

2017
T. Patrick Montgomery Adam M. Johns Robert H. Grubbs

Olefin metathesis is a prevailing method for the construction of organic molecules. Recent advancements in olefin metathesis have focused on stereoselective transformations. Ruthenium olefin metathesis catalysts have had a particularly pronounced impact in the area of stereoselective olefin metathesis. The development of three categories of Z-selective olefin metathesis catalysts has made Z-ole...

2012
M. S. WONG E. N. MUHAMAD

Ni-, Co-, and Ptpromoted MoVNbOx mixed metal oxide catalysts were prepared by impregnation method. The physicochemical properties of the catalysts showed that the BET surface area of the promoted catalysts was lower when compared to the unpromoted catalysts due to the filling of open pores by the promoters. X-ray diffraction (XRD) analysis indicated that the main reflections were consistent wit...

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