Gold catalysts, supported nanocrystalline

Tang, Z., Edwards, J., Bartley, J., Taylor, S., Carley, A., Herzing, A., Kiely, C., and Hutchings, G. (2007) Nanocrystalline cerium oxide produced by supercritical antisolvent precipitation as a support for high-activity gold catalysts. J. Catal,... 

Cyclic Voltammetry as a Potential Predictive Method for Supported Nanocrystalline Gold Catalysts for Oxidation in Aqueous Media... 

Recent studies of ceria systems have focused on the development of synthetic approaches to make size-controlled and shape-controlled nanostructures. The thermolysis of an acidified Ce(N03)4 solution was reported as a method for the preparation of nanocrystalline CeOg ( 4 nm, surface area 180 m -g ). The deposition of gold on these nanocrystalline particles provides experimental evidence for the size effect of supports. It was shown that the activity of the resulting gold catalyst in CO oxidation was two orders of magnitude higher than that of catalysts prepared by co-precipitation or by Au deposition on a regular cerium oxide support (surface area 70 m -g ). 

Nanoparticlulated gold supported by nanocrystalline or mesostruc-tured nanocrystalline ceria catalysts represents an alternative to catalysts for selective aerobic oxidation of aliphatic and aromatic aldehydes which is much better than the gold supported by the precipitated ceria (Corma and Domine, 2005). The ceria or yttria supported Au are also active and extremely selective for the homocoupling of arylboronic acids, and the activity is directly correlated with Au(lll) (Carrettin et al., 2005). 

Catalytic properties Phosphorus is known to have deactivation effects for some automotive catalysts and the formation of CeP04 has been identified in phosphorus contaminated catalysts (Uy et al., 2003). Nanocrystalline LaP04 would act as Lewis acid in a catalytic process, which could be determined by a temperature-programmed ammonia adsorption/desorption process (Onoda et al., 2002 Rajesh et al., 2004, 2007). In addition, the rare earth phosphate NCs could act as supports for example, Pd, Pt, or Rh supported on RPO4 show excellent catalytic reduction of NO into N2 and O2 (Tamai et al., 2000), and gold supported on RPO4 shows catalytic activity and stability for CO oxidation. 

Gold derivatives have also been found to facilitate the Mannich reaction.Thus, the heterogeneous catalyst, gold supported on nanocrystalline Ce02 or Zr02, was found to accelerate the reaction of aldehyde 26, amine 54, and acetylide 55 to produce 56, with a turn-over number (TON) 50-fold greater than the homogeneous variation. 

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