Effects of partial substitution of Cu by Mn and Co in LaCu0.5Ni0.5O3 catalyst synthesized by mechanochemical method in the total oxidation of methane

摘要

This study pertains to the effects of Cu substitution by Mn and Co on the textural properties and catalytic activity of the LaCu0.5-xMnxNi0.5O3 (x= 0, 0.1, 0.3) and LaCu0.4Co0.1Ni0.5O3 catalysts for methane catalytic combustion. The perovskite catalysts were prepared by a solvent-free mechanochemical synthesis method. The catalytic results showed that adding Mn into the structure of LaCu0.5Ni0.5O3 improved the catalytic activity and thermal stability and also increased the specific surface area, whereas the addition of Co=0.1 led to a slight decrease in catalytic performance and specific surface area. The H-2-TPR results illustrated that the substitution of Mn improved the reducibility feature of the catalysts. Among all the samples, LaCu0.2Mn0.3Ni0.5O3 catalyst exhibited the highest catalytic activity. The combustion of methane is a type of interfacial reaction, and considering the Mars-Van Krevelen mechanism, the increase in the catalytic activity can be related to the increment of lattice oxygen mobility and oxygen vacancy. Moreover, the decrease in calcination temperature of the LaCu0.2Mn0.3Ni0.5O3 improved the catalytic activity due to the increase in the BET area and the concentration of oxygen vacancy.