Studies on Au catalysts for water gas shift reaction

摘要

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 H2_O, with H2_O/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 H_2 and CO_2) 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.