Preparation Of Alumina Supported Gold Catalyst For CO Oxidation

It is now apparent that the preparation of catalyst with high activity and gold stability in CO oxidation has witnessed a rapid growth of interest in the field of chemical processing, such as pollution abatement, fuel cells, gas masks, enclosed CO2 lasers. Due to the outstanding low-temperature activity of CO oxidation, the supported gold catalyst has a broad prospect of application, but limited by its unsatisfied catalytic stability. Therefore, the preparation of active and stable gold catalyst has becoming a challenging research project.In this paper, alumina materials and Au/Al2O3 catalysts were prepared by different routes. Besides, we studied the catalytic activity and thermostability for CO oxidation, the stability in reactive and moisture atmospheres, and the life of catalysts in room temperature. In addition, the influence of preparation methods, pretreatment conditions and chloride ion were also investigated.In the first part, glassy alumina with different pore structures was prepared in nanocasting method, using carbon aerogels as templates. Then, gold nanoparticles were supported on this alumina by deposition of colloidal gold sol or deposition-precipitation method. It suggests that the catalytic activity of Au/Al2O3 catalysts in deposition-precipitation method was higher than that prepared by deposition of colloidal gold sol. It is strange that, the activity of the catalysts decrease slightly when increasing the BET surface area of the supports.In the second part, hierarchical flake-like Al2O3 materials were synthesized by a non-template hydrothermal route using aluminium nitrate as precursor and X as precipitating agent. The Au/Al2O3 catalyst supported on this alumina shows great performance in CO oxidation. After calcinated at 700℃in air for 2 h, the completely transfer temperature of CO can still as low as 30℃, and the average partcle size of the gold particles is 2.2 nm.Finally, modified alumina supports with different morphology were synthesized by hydrothermal method. Then the performance of the gold catalysts supported on the alumina was tested. The experiment results proved that, the Au/Al2O3 catalyst supported on aloe-like alumina shows great react stability in both normal reaction atmosphere and the reaction atmosphere with 5.8% moisture. It also can maintain long catalyst life when exposed to the air and light.