Defect engineering on Ce2Co1Cu1Ox catalyst surface via NaOH modification: Boosting the catalytic oxidation toluene performance by reducing intermediates and increasing ring-open ability of benzoate

Abstract

Catalytic oxidation is still an effective approach to eliminate volatile organic compound (VOCs). In order to explore the promotion mechanism for the improvement of toluene oxidation capacity over NaOH-modified Ce2Co1Cu1 catalyst (Ce2Co1Cu1-AT), NaOH-modified catalysts with similar physical-structure and chemical properties were prepared by modified co-precipitation, impregnation and etching methods, respectively. Characterization results revealed that NaOH modification could generate a large number of defects, oxygen vacancies as well as abundant active sites on the surface of Ce2Co1Cu1, the concentration of surface adsorbed oxygen species and the mobility of surface lattice oxygen species were both increased. Hence, the catalyst's redox capacity was enhanced, the accumulation rates of benzyl alcohol and benzaldehyde were much lower (reduced about 69 % and 83 %, respectively), and the negative effect of the accumulation of intermediate species covering the reactive site was weakened. Benefiting from these, the toluene oxidation performance of the NaOH-modified catalysts was significantly improved, with T90 (191 ℃) of Ce2Co1Cu1-AT was nearly 20 ℃ lower than that of the un-modified catalyst, which is among the best reported activity values. Additionally, it also exhibited excellent thermal stability and water resistance. This work may provide a new strategy to design and synthesize the high-efficiency VOCs catalyst.