Chemical vapor deposition of gold on Al2O3, SiO2, and TiO2 for the oxidation of CO and of H2
ABSTRACT In order to clarify the effect of metal oxide support on the catalytic activity of gold for CO oxidation, gold has been deposited on SiO2 with high dispersion by chemical vapor deposition (CVD) of an organo-gold complex. Comparison of Au/SiO2 with Au/Al2O3 and Au/TiO2, which were prepared by both CVD and liquid phase methods, showed that there were no appreciable differences in their catalytic activities as far as gold is deposited as nanoparticles with strong interaction. The perimeter interface around gold particles in contact with the metal oxide supports appears to be essential for the genesis of high catalytic activities at low temperatures.
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ABSTRACT: The meso silica supported novel nano-size gold catalysts promoted by MgO have been synthesized using deposition–precipitation technique for the total oxidation of carbon monoxide. The effects of MgO promoter and preparation procedure on the structure and performance of gold catalysts have been investigated. Better gold dispersion, smaller average size of Au particles and more oxygen mobility were observed in the Au/MgO/SiO2-SH catalyst using NaOH as precipitation agent, over which the turnover frequency (TOF) was much better than that of the sample without promotion. The temperature of the CO total conversion over the sample Au/MgO/SiO2-SH is about 250K lower than that over the silica which directly supported gold catalyst.Chemical Engineering Journal 06/2011; 170(2):419-423. DOI:10.1016/j.cej.2010.12.051 · 4.32 Impact Factor
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ABSTRACT: AbstractGold nanoparticles (AuNPs) have been incorporated into undoped Si-MCM-41 by direct one-pot and post-synthesis approaches. Through a “modified deposition–precipitation” (mDP) method, whereby ethylenediamine served as both a base and complexing agent for the Au(III) species, Au nanoparticles have been prepared exclusively inside the pore channels of Si-MCM-41 materials. The method exploits Coulombic interactions between the occluded cationic surfactant template and the anionic [AuCl4]− to yield a controlled distribution and in-pore generation of AuNPs, i.e., DP of the Au precursor was aided by electrostatics. This method is simple and yields well-dispersed gold nanoparticles (AuNPs). The nanoparticles inside the matrix were seen to aggregate and migrate to the surface upon calcination at 500°C, but showed a narrow Au particle size distribution. The nanocomposite materials synthesized in this study exhibited catalytic activity for the CO oxidation reaction, with CO conversion of<100% even at temperatures as high as 500°C. Graphical Abstract KeywordsModified deposition–precipitation-As-synthesized Si-MCM-41-Gold nanoparticles-Surface migration-Coulombic interactionsCatalysis Letters 03/2010; 135(1):1-9. DOI:10.1007/s10562-010-0300-9 · 2.29 Impact Factor
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ABSTRACT: We investigated Au catalysts supported on TiO2, Fe2O3, and ZnO for their preferential oxidation of CO in a H2-rich atmosphere. Both full conversion and selectivity were achieved over Au/Fe2O3 and Au/ZnO around room temperature, but at higher temperatures the CO conversion was suppressed due to competition between CO and H2.Catalysis Letters 08/2008; 124(1):68-73. DOI:10.1007/s10562-008-9501-x · 2.29 Impact Factor