Study of H_2-TPR and Performance of Pd Catalysts for CH_4 Concentration Detection

A catalyst support γ-Al2O3 with pore size distribution of 50-100 nm was prepared by a sol-gel method,and promoters CeO2,K2O and MgO were loaded on the support by a dip-molding method.The catalytic activity of the catalysts Pd/Al2O3modified by promoters for CH4 oxidation reaction was investigated.The results show that the catalytic activity and stability of these catalysts were improved.The catalyst loaded with 20% CeO2 is of better catalytic activity and stability.The conversion ratio of CH4 of 90% and 10% were achieved at 351 ℃ and 252 ℃ respectively.Compared with catalyst Pd/Al2O3,the corresponding temperature were decreased by 125℃ and 118℃ respectively while the same conversion ratio of CH4.The results tested by H2-TPR show that only one reduction peak of PdO species on the catalyst appeared at 110-170 ℃.The peak size and the temperature of PdO species reduced by H2 were coincident with the catalytic activity of the catalyst.