نتایج جستجو برای: catalyst

تعداد نتایج: 44027  

Journal: :Chemical communications 2014
Yongsheng Yang Jiayi Guo Huimin Ng Zhiyong Chen Peili Teo

The hydration of terminal olefins to secondary alcohols has been achieved using a Pd(II)/Ru(II) catalyst combination with high regioselectivity and yields. Both vinyl arenes and aliphatic olefins can be hydrated easily with the tandem catalyst system using a low catalyst loading of 1 mol%.

2014
Michaela Nebel Thomas Erichsen Wolfgang Schuhmann

Multidimensional shearforce-based constant-distance mode scanning electrochemical microscopy (4D SF/CD-SECM) was utilized for the investigation of the activity distribution of oxygen reduction catalysts. Carbon-supported Pt model catalyst powders have been immobilized in recessed microelectrodes and compared to a spot preparation technique. Microcavities serve as platform for the binder-free ca...

Journal: :Molecules 2013
Jinlong Wang Hongbo Yu Zhen Ma Shenghu Zhou

An egg-shell Pd/Al2O3 catalyst showed higher activity than a regular Pd/Al2O3 catalyst in the partial oxidation of methane to syngas, but a common problem of this reaction is the catalyst deactivation on stream. We attempted to modify the egg-shell catalyst via impregnation with some metal oxide additives. Although the addition of MgO did not show any beneficial effect, the addition of CaO and/...

2004
Sudip Mukhopadhyay Alexis T. Bell

Direct sulfonation of methane with SO3 to methanesulfonic acid (MSA) is accomplished in sulfuric acid with almost 100% selectivity in the presence of a catalyst, namely, Ce and Rh salts and molecular oxygen as the catalyst regenerator. In the absence of O2, the catalyst remains effective but the selectivity to MSA decreases to 53% and byproducts, principally CH3OSO3H, are formed. The effects of...

2001
Pranav Anand David Anderson John D. Burger John Griffith Marc Light Scott A. Mardis Alexander A. Morgan

Qanda is MITRE’s entry into the question-answering (QA) track of the TREC conference(Voorhees & Harman 2002). This year, Qanda was re-engineered to use a new architecture for human language technology called Catalyst, developed at MITRE for the DARPA TIDES program. The Catalyst architecture was chosen because it was specifically designed for fast processing and for combining the strengths of In...

Journal: :Dalton transactions 2017
Yulian Duan Tao Wang Qingxiao Xie Xiaobo Yu Weijie Guo Shutao Wu Danfeng Li Jianhui Wang Guiyan Liu

An indolinooxazolidine tagged N-heterocyclic carbene Ru olefin metathesis catalyst was synthesized and the molecular structure of this new Ru complex was determined by single crystal X-ray diffraction. This complex is a homogeneous catalyst and can be recovered by controlling the polarity of the indolinooxazolidine tag. Under acidic conditions the indolinooxazolidine tag exists as an open proto...

Journal: :iranian journal of chemistry and chemical engineering (ijcce) 2004
shohreh fatemi giti abolhamd mohammad ali moosavian yadollah mortazavi

a study was made of the coking of a commercial fresh sulfide ni-mo/al2o3 catalyst in a fixed-bed reactor. the catalyst was coked using different coke precursors in the gas oil under accelerated conditions at temperatures of 400 to 450°c to yield different deactivated catalysts containing 2-20 wt% c. two cases were studied; crushed catalyst without diffusional resistance and extruded pellets wit...

Journal: :journal of nanostructures 2012
j. safaei-ghomi s. rohani a. ziarati

cui nanoparticles as an expedient and recyclable catalyst for the synthesis of n-cyclohexyl-3-aryl-quinoxaline-2-amines in ethanol via a multi-component reaction are established. the products were separated from the catalyst simply by filtration. the catalyst could be recycled and reused for several times without noticeably decreasing the catalytic activity.

2010
Eugene Leo Draine Mahmoud

Due to the feasibility of ethanol production in the United States, ethanol has become more attractive as a fuel source and a possible energy carrier within the hydrogen economy. Ethanol can be stored easily in liquid form, and can be internally pre-formed prior to usage in low temperature (200 o C – 400 o C) solid acid and polymer electrolyte membrane fuel cells. However, complete electrochemic...

2009
Jianfen Li Bo Xiao Rong Yan Jianjun Liu

The objective of this study was to develop a supported tri-metallic catalyst (nano-Ni-La-Fe/γ-Al2O3) for tar removal in biomass steam gasification, to significantly enhance the quality of the produced gas. For this purpose, the supported tri-metallic catalysts were prepared by a deposition-precipitation (DP) method. Different analytical approaches were used to characterize the synthesized catal...

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