Studies on Au catalysts for water gas shift reaction

Gold-supported catalysts on alumina and ceria were prepared by means of deposition–precipitation method at different pH and molarity of the precursor solution. The screening at the powder level in a fixed bed micro-reactor of the catalytic activity of the 3% Au prepared catalysts, in terms of CO conversion for the WGS reaction, highlighted that the catalysts on alumina were not so active (maximum conversion of 30%), despite a satisfactory gold deposition on the support. On the contrary, ceria-based catalysts displayed better performances. By feeding only CO and H2O, with H2O/CO ratio equal to 4, catalysts prepared at different pH and M = 1 × 10−3 approached satisfactorily the equilibrium WGS conditions, in particular when pH = 8.5 was used. However, catalytic activity tests carried out with a realistic reformate feed (containing also H2 and CO2) showed fairly low CO conversions also at high temperature. Then, on this catalyst, tests at different weight space velocities WSV were carried out obtaining better performance by lowering WSV.