A highly-efficient La–MnOx catalyst for propane combustion: the promotional role of La and the effect of the preparation method

Abstract

A La-modified MnO_x catalyst was developed for the total oxidation of C₃H₈. The promotional role of La and the effect of the preparation method on the structural, physicochemical and catalytic properties of the La–MnO_x catalyst were investigated. The results show that the presence of La in MnO_x can remarkably improve the oxygen reactivity of MnO_x and promotes the reduction properties of Mn species with the aid of a strong interaction between Mn and La. The preparation method obviously affected the crystal structure, lattice defects, surface phase composition, reduction properties and apparent morphology of the La_0.4–MnO_x catalyst. When the La_0.4–MnO_x (C-0.4) catalyst was prepared by using the co-precipitation method, it exhibited excellent catalytic performance, good thermal stability and enhanced H₂O resistance to the title reation, because the C-0.4 sample possesses a higher atomic ratio of Mn⁴⁺/Mn³⁺ (2.03) and contains more absorbed oxygen species and high activity and mobility of lattice oxygen. In addition, the catalytic reaction mechanism of C₃H₈ oxidation was not changed by La doping but promoted the C₃H₈ adsorption on the catalyst surface, resulting in the acceleration of its rate-determining step to a large extent.