Study Of CO Selective Oxidation In Catalysts In Hydrogen-Rich Gas

The catalysts of activity and selectivity for CO oxidation in hydrogen-rich gas, prepared by coprecipitation, impregnation and deposition-precipition method, was studied. Effects of preparation condition and reaction condition on the catalytic performance have been investigated and the catalysts were characterized by XRD,TEM and FT-IR methods.It was found that the preparation condition has great influence on the catalytic performance of the catalysts,Au(2%)/ZnO(2%)/TiO₂ and Au(2%)/NiO (5%)/TiO₂ catalysts prepared by deposition- precipition method has higher activity than other catalysts. The results indicated that catalyst has best performance when it is calcinated at 300℃for 3h, pretreated in H₂ at 300℃for 6h, urea as precitant and PH value should be controlled in the range of 9-11.Effect of reactions on the catalysts was investigated. Because the reaction of CO selective oxidation in hydrogen-gas is emitting heat reaction, The optimum reactive conditions for catalyst are: the reaction optimum temperature at 30℃, the catalyst Au(2%)/NiO(5%)/TiO₂ can keep good stability for 48h when Space velocity ( WHSV ) reaches to 3000h^-1, and the catalyst Au/ZnO/TiO₂ keep good stability for 28h when Space velocity reaches to 2000h^-1. The best method of regeneration is catalysts calcinated at300℃for 6h.It was found that add promoter can improve the distribution of active components of catalyst with the aid of TEM and XRD patterns. But the experiments' data indicated that the catalyst's deactivation was caused by C-O bond compound which produced during reaction process.To sum up, Au(2%)/ZnO(2%)/ TiO₂ and Au(2%)/ NiO(5%)/TiO₂ catalysts prepared in a certain condition can be promising candidates for selective oxidation of CO in hydrogen-rich environment under a certain reaction condition.