Monolithic gold catalysts: Preparation and their catalytic performances in water gas shift and CO oxidation reactions

Two different protocols for washcoating supported Au powder catalysts, prepared via different methods, onto a cordierite monolith were developed. The influence of the pH, the type of washcoat binder and organic solvent on the Au particle size and on the washcoat adherence was investigated. For Au powder catalysts prepared by a sonochemical method, the Au particle size was mainly influenced by the pH value, thus an one-stage coating process was applied at pH between 6–8; for Au powder catalysts prepared by co-precipitation and deposition-precipitation methods, the Au particle size was mainly influenced by the type of organic solvent and binders used. Therefore, a two-stage washcoating process was developed, in which, the catalyst support (α-Fe2O3) was first coated, and the Au powder catalyst was then successively coated on this first layer with a benign solvent. The catalytic performances of the powder and monolithic Au catalysts in CO oxidation and WGS reactions were investigated.