Synthesis and characterization of novel Au/θ-Al2-xFexO3 nanomaterials with high thermal stability in catalytic oxidation of carbon monoxide

Abstract

Applications as a catalyst in engine exhaust systems require a uniform distribution of gold nanoparticles on a thermally stable alumina support. The novel thermally stable nanomaterials comprised of gold nanoparticles on the iron-modified theta-alumina support have been synthesized by the method of deposition-precipitation using urea. The material precursor was proved to involve both a gold precursor and adsorbed urea. The generation of gold nanoparticles from the gold precursor occurred below 300°C, whereas the complete elimination of organic compounds proceeded only at 500°C in air or even at 650–700°C in a reducing gas flow. The gold particle size distribution was narrow with a mean size about 2nm and 3.4nm after calcination at 300°C and 500°C respectively. The prepared materials are highly active and stable as the catalysts of carbon monoxide oxidation in the presence of ammonia, and maintain the catalytic activity even after prolong thermal treatment at 750°C.