Study On The Catalytic Performance Of Au/perovskite For The Oxidation Of CO

Two concepts have been considered here to synthesize new types of Au catalysts to improve their adaptability to H2O in a more practicable way. Firstly, reasonable elements together with Au are deliberately chosen to form a possible peroskite-type catalyst according to the theory of crystalline structure. The method of sol-gel is introduced to prepare the catalysts. The selection of different ligands, the span and the temperature of calcination adopted for the formation of the particular structure, as well as the influence of ions occupying the position of B in an ABO3 lattice are discussed. Secondly, Au catalysts with a mixture of MgO and Fe2O3 as the support are synthesized by means of co-precipitation. The catalytic activities of these samples on the oxidation of CO are measured and their properties are characterized by means of XRD,TPR, BET, SEM, etc..The performances of LaCoO3 and LaFeO3 are partly increased when the content of Au is no more than 3 percent. Not All the atoms of Au can occupy the positions of the lattice in the perovskite for over-loaded samples. It will depress the activity of such a catalyst because of the agglomeration of Au atoms. But for LaMnO3, things go different. Its activity will certainly decrease when Au is introduced. The ions occupying the position of B in the lattice has a notable influence on the activity of the oxidation of CO. Au-LaCoO3 is the most active with the same content of Au.Among all the Au catalysts acquired here, the sample of is more dispersed and active for the oxidation of CO than the other. There are so many complicate ingredients in the support that it can't beascribed to a simple mixture of MgO and Fe2O3. It can be concluded that the kind and the content of such ingredients have a deep influence on the catalytic activity.Attention should be paid to the span and the temperature of calcination. The higher the temperature or the longer the span is, the larger the size of Au particle would be. The existence of Cl－ tends to debase, to be more serious, even make the catalyst entirely lose the its activity. In the case of Au catalysts, it is important to adopt reasonable methods to remove Cl－ caused by source materials for fulfill the excellent capability of low-temperature oxidation of CO.