Surface engineering of ternary mixed transition metal oxides for highly efficient catalytic oxidation of low concentration VOCs

Abstract

With the widespread application of waterborne painting process, effective removal technologies for low concentration volatile organic compounds (VOCs) is a major concern of the painting industries due to the low mass transfer efficiency. This work presents a unique approach for the molecular-level preparation of precious-metal-free mixed aliovalent-substituted, CeCuOx binary oxide and NiO-modified yNi/CeCuOx ternary mixed metal oxide catalysts. In addition, the excellent catalytic selectivity (no catalytic activity decreases under 5.0 vol% water vapor) of the catalysts was successfully achieved by microstructures optimization and grafting octadecyltrichlorosilane (OTS). Its catalytic activity in the oxidation of toluene at low concentrations (50 ppm) was studied. The 3Ni/CeCuOx sample exhibits the best performance, which achieve 90 % catalytic oxidation of toluene at 197 °C without using noble metals. This results from that the ternary doping and the growth of NiO increases the specific surface area, active lattice oxygen species, activates molecular oxygen species, and provides more catalytic sites, which improve the adsorption and catalysis of toluene. Furthermore, the catalytic stability of the catalysts is also significantly improved by the addition of the hydrophobic coating. Therefore, the unique catalysts have great potential in practical applications for low concentration VOCs removal of painting industries.