نتایج جستجو برای: homogenous catalysts

تعداد نتایج: 43488  

2008
P. Deshlahra

Introduction Model supported catalysts on flat surfaces form an important link between single crystal surfaces and real world supported catalysts. The use of nanofabrication techniques to prepare such model catalysts has received a lot of attention in recent years [1]. In the present study Pt/TiO2 catalysts have been fabricated using e-beam lithography (EBL) and used to characterize the electri...

Journal: :Journal of the American Chemical Society 2009
Prabani Dissanayake Matthew J Allen

There is tremendous interest in water-compatible lanthanide triflate-based catalysts for carbon-carbon bond forming reactions; however, poor understanding of their aqueous mechanism severely limits the ability to increase the utility of these catalysts. Here, we report dynamic measurements of the water-coordination number of lanthanide triflate-based catalysts using luminescence-decay measureme...

2014
P. K. Saini C. K. Williams

Some of the most active catalysts for carbon dioxide and epoxide copolymerization are dinuclear metal complexes. Whilst efficient homodinuclear catalysts are known, until now heterodinuclear catalysts remain unreported. Here, a facile, in situ route to a catalyst system comprising amixture of homoand heteronuclear Zn–Mg complexes is presented. This catalyst system shows excellent polymerization...

2016
Wei Xu Zucheng Wu Shanwen Tao

Recently mesoporous materials have drawn great attention in fuel cell related applications, such as preparation of polymer electrolyte membranes and catalysts, hydrogen storage and purification. In this mini-review, we focus on recent developments in mesoporous electrocatalysts for polymer electrolyte membrane fuel cells, including metallic and metal-free catalysts for use as either anode or ca...

2013
Hui Mao Hong Yu Jing Chen Xuepin Liao

In the field of catalysis, it is highly desired to develop novel catalysts that combine the advantages of both homogeneous and heterogeneous catalysts. Here we disclose that the use of plant polyphenol as amphiphilic large molecule ligand/stabilizer allows for the preparation of noble metal complex and noble metal nanoparticle catalysts. These catalysts are found to be highly selective and acti...

2016
Jason A. Varnell Edmund C. M. Tse Charles E. Schulz Tim T. Fister Richard T. Haasch Janis Timoshenko Anatoly I. Frenkel Andrew A. Gewirth

The widespread use of fuel cells is currently limited by the lack of efficient and cost-effective catalysts for the oxygen reduction reaction. Iron-based non-precious metal catalysts exhibit promising activity and stability, as an alternative to state-of-the-art platinum catalysts. However, the identity of the active species in non-precious metal catalysts remains elusive, impeding the developm...

2016
Koji Endo Robert H. Grubbs

The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(i) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelat...

Journal: :Electronic Colloquium on Computational Complexity (ECCC) 2013
Mrinal Kumar Shubhangi Saraf

We study the class of homogenous ΣΠΣΠ(r) circuits, which are depth 4 homogenous circuits with top fanin bounded by r. We show that any homogenous ΣΠΣΠ(r) circuit computing the permanent of an n× n matrix must have size at least exp ( n ) . In a recent result, Gupta, Kamath, Kayal and Saptharishi [6] showed that any homogenous depth 4 circuit with bottom fanin bounded by t which computes the per...

2010
Xiaoming Wang Nan Li Lisa D. Pfefferle Gary L. Haller

Pt monometallic and Pt-Co bimetallic catalysts have been prepared on single-walled carbon nanotubes (SWNT) with and without HNO3 treatment. The HNO3 treatment introduced oxygen containing groups (OCGs), which affect both the structure and activity of the catalyst. The introduction of OCGs does not affect the structure of Pt monometallic catalysts but increased the dispersion in the bimetallic c...

2011
Xianlong Zhang Bowen Shi Xueping Wu Zhanggen Huang Zhenyu Liu Baojun Yang Cuiping Zhang

Simulated compounds were prepared by loading K2SO4 onto V2O5/AC catalysts. Study the effect of K2SO4 on V1/AC catalysts in the presence of low concentration SO2. Transient response techniques, TPD was carried out. The results indicated that the DeNO activity of V1/AC catalysts was decreased seriously in the early period of operation, but the deactivation was gradually diminished with SO2 adsorp...

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