Preparation and evaluation of the LaCu1-xNixO3 (x = 0, 0.1, 0.3, 0.5 and 0.7) perovskite catalysts for total oxidation of methane

A series of Ni-substituted LaCu_1-xNi_xO₃ (x = 0, 0.1, 0.3, 0.5 and 0.7) catalysts were prepared by a mechanochemical synthesis method and the prepared samples were used in catalytic combustion of methane. The catalytic results indicated that the partial substitution of Ni affected the catalytic performance and the increase in nickel content increased the catalytic activity and among the prepared catalysts the LaCu_0.5Ni_0.5O₃ sample possessed the highest catalytic activity and thermal stability. The results showed that methane conversion reached from 7.8 to 73.8% at 500 °C with the substitution of Ni in the amount of x = 0.5. Also, the addition of Ni instead of Cu in the LaCu_1-xNi_xO₃ led to an increase in total pore volume and specific surface area and a decrease in average crystalline size. According to O₂-TPD profiles of the LaCu_1-xNi_xO₃ catalysts, mobility of lattice oxygen (O²⁻) has a crucial role in determining the performance of these catalysts. The H₂-TPR results indicated that the addition of Ni slightly improved the reducibility of catalysts. Furthermore, a decrease in calcination temperature of LaCu_0.5Ni_0.5O₃ catalyst resulted in an increase in the catalytic activity due to the enhancement in the concentration of oxygen vacancy and specific surface area. Also, the results revealed that the increase in feed ratio (CH₄/O₂) leads to an increment in methane conversion.