Catalytic oxidation of toluene using layer-modified Mn-Ce solid solution with high specific surface area

Abstract

Numerous studies have been reported on the application of Mn-Ce catalysts for the catalytic oxidation of toluene, and the modification of their physical structure has become an important method to favour toluene adsorption. This paper modified (MnCe)Ox by using a series of organic solutions. The catalysts modified by different organic solutions were prepared for the catalytic oxidation of toluene by impregnation method with calcination at 500 °C. Activity test results showed that the MC-TPAOH catalyst modified by tetrapropylammonium hydroxide solution had the best catalytic performance, with T50 and T90 of 192 °C and 221 °C. The MnO2 species on the surface of the catalyst modified by the organic solution were in an amorphous state, and the solid-solution effect of Mn-Ce was enhanced. Tetrapropylammonium hydroxide has greater solubility in polar solvents due to its higher number of C atoms and exhibits stronger phase-transfer ability, which was favourable to the Mn-Ce interaction. The structural properties of the catalyst were modulated by lamellar modification, which increased the specific surface area and formed a porous structure. The redox capacity was greatly improved, and more oxygen vacancies were exposed on the surface, which was conducive to the migration of active oxygen species. Reactive oxygen species present on the catalyst surface were the basis for its excellent activity. This study modifies (MnCe)Ox by organic solution to avoid the introduction of impurity ions. It opens a new direction for the physical structure modulation of Mn-Ce composite oxides and lays a research foundation for the organic modification of Mn-Ce composite oxides.