Gold-based catalyst

Liu Z-P, Gong X-Q, Kohanoff J, et al. 2003. Catal3dic role of metal oxides in gold-based catalysts A first principles study of CO oxidation on Ti02 supported Au. Phys Rev Lett 91 266102. 

Gold-based catalysis has attracted considerable attention in recent years. A gold-catalyzed aziridination reaction has recently been reported <06JOC5876>. A series of gold catalysts were examined for their ability to catalyze the aziridination of styrene with p-nitrophenylsulfonamide (NsNH2). Styrene and phenyl-substituted styrenes provided the N-nosyl aziridines in good to excellent yields. Cinnamate however provided the aziridine product in only 25% yield. The use of other sulfonamides (e.g. tosyl, trichloroethyl) gave much lower yields of the aziridine product. 

Intermolecular addition of activated methylenes to unsaturated systems has been investigated with silver,36 silver/ gold, and palladium catalysts. Thus, C-H addition of 2,4-pentandione to 1,3-cyclohexadiene occurs in THF at 0°C with 5mol% of palladium(ll) catalyst without base. Josiphos ligand 20 is used as a chirality source to induce... 

Selective Oxidation with Molecular Oxygen on Gold-based Catalysts 237... 

CHAPTER 14. Gold-Based Nanoparticle Catalysts for Fuel Cell... 

For the study of the electrocatalytic reduction of oxygen and oxidation of methanol, our approach to the preparation of catalysts by two-phase protocol " provides a better controllability over size, composition or surface properties in comparison with traditional approaches such as coprecipitation, deposition-precipitation, and impregnation. " The electrocatalytic activities were studied in both acidic and alkaline electrolytes. This chapter summarizes some of these recent results, which have provided us with further information for assessing gold-based alloy catalysts for fuel cell reactions. 

Rossignol, C. and Arrii, S. and Morfin, F. and Piccolo, L. and Caps, V. and Roussel, J. (2005). Selective oxidation of CO over model gold-based catalysts in the presenee of H2. Journal of Catalysis, 230,476-483. 

Another way to produce acetic acid is based on a carbonylation of methanol in the so called Monsanto process, which is the dominant technology for the production of acetic acid today [15]. Acetic acid then is converted to VAM by addition of ethylene to acetic acid in the gas phase using heterogeneous catalysts usually based on palladium, cadmium, gold and its alloys (vinylation reaction 3 in Fig. 2) [16] supported on silica structures. 

Oxidation of Glucose over Gold-Based Solid Catalysts. 83... 

In this chapter, it will be shown that the detection of sodium dithionite on bare gold electrodes can be improved by electrocatalysis using a cobalt(II)tetrasulphonated phthalocyanine, sodium salt (CoTSPc) or a 5,10,15,20-tetrakis-(4-sulphonatophenyl)porphyrin cobalt(II), tetrasodium salt (CoTSPor) as catalyst. The selection of these catalysts was based on... 

The catalyst plays a crucial role in technology. Previously, catalysts were based on palladium of 1 to 5 wt% impregnated on silica with alkali metal acetates as activators. Modern catalysts employ as enhancers noble metals, mostly gold. A typical Bayer-type catalyst consists of 0.15-1.5 wt% Pd, 0.2-1.5 wt% Au, 4-10 wt% KOAc on spherical silica particles of 5 mm diameter [14], The reaction is very fast and takes place mainly inside a thin layer on the particle surface (egg-shell catalyst). 

A gold-based material has been formulated for use as a three-way catalyst in gasoline and diesel applications.28 This catalyst, developed at Anglo American Research Laboratories in South Africa, consisted of 1% Au supported on zirconia-stabilized-Ce02, ZrC>2 and TiC>2, and contained 1% CoOx, 0.1% Rh, 2% ZnO, and 2% BaO as promoters. The catalytically active gold-cobalt oxide clusters were 40-140 nm in size. This catalyst was tested under conditions that simulated the exhaust gases of gasoline and diesel automobiles and survived 773 K for 157 h, with some deactivation (see Section 11.2.7). 

Moving from a fixed to a fluidised-bed operation also required a new catalyst, and the one selected was a supported gold palladium system in the form of very fine spheres, prepared in collaboration with Johnson Matthey. Hence, gold-based catalysts are being used for this new fluidised-bed process, and are well established in fixed-bed processes for the large-scale manufacture of VAM. 

Diver has recently reported new entries for the assembly of tetracyclic derivatives [89]. Interestingly, ruthenium metathesis-type catalysts have also given birth to tricyclic derivatives incorporating a cyclopropane from di-enynes [90]. Cationic gold-based catalysts have proven to be even more reactive promotors of various reactions resulting from a preliminary electrophilic activation [91]. They also allow the formation of tetracyclic derivatives 140 from acyclic precursors 139 at low temperature and as single diastereomers. In one case, the minor metathesis diene 141 was isolated. Tetracyclic products... 

HIV-1 integrase ChemBridge (150,000) HipHop/Catalyst + GOLD Ligand-based pharmacophore + docking 110 18.0 20 (llpM) [52]... 

Over rhodium-supported on AI2O3, the reaction takes place at temperatures above 400 K [508,509], showing that under oxygen-free conditions, gold-based catalysts easily outperform those based on the PGMs for this reaction. 

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