Influence of Pd/γ-Al2O3 catalyst modified by La/Mn on methane catalytic combustion

Four kinds of palladium catalysts, supported on γ-Al2O3 and promoted by La and/or Mn, were prepared by impregnation method. The physico-chemical properties of these catalysts were characterized by BET and XRD techniques. The effect of methane combustion activity of the catalyst samples were investigated. The results indicat that the catalyst mixed with the transition metal Mn leads to an enhancement in methane combustion, whereas accelerates transition of γ-Al2O3 to α-Al2O3. The catalyst mixed with the earth metal La does not improve methane combustion activity obviously, but restrains transition γ-Al2O3 to α-Al2O3 as well as enhances thermal stability of catalysts under high-temperature calcination. 0.5Pd/Mn/Al2O3 performs reasonably better catalytic activity during low temperature stage, however 0.5Pd/LaMnAl11O19 shows the best catalytic active among the all catalysts under high temperature stage. As a interim product of CH4, CO yield increases gradually between 700C and 800C, which is caused by decomposition of PdO to Pd with less activity. After that, CO yield derceases quickly and nearly disappears when the temperature rises to 830C caused by cooperate effect of catalytic activity and homogeneous combustion. ©2009 Chin. Soc. for Elec. Eng.