Catalytic oxidation of acetone in air over Ag modified CeO2 catalysts under VUV irradiation: Comparison of different treatment process, performance, and mechanism studies

Abstract

In this study, the performance of different treatment processes, including UV photolysis, ozonation, UV photolysis + ozonation, and vacuum ultraviolet (VUV) photolysis for oxidation of acetone in the presence and absence of Ag modified CeO2 photocatalysts was investigated. The as-synthesized catalysts were characterized using XRD, XPS, Raman Spectroscopy, BET, SEM, HRTEM, and EDX techniques. The attained data showed that by introducing Ag nanoparticles into the CeO2 network, the oxygen storage capability of the catalyst increases, which facilitates the generation of oxygen vacancies leading to the activation of lattice oxygen. The mechanism of the acetone oxidation and the contribution of each participating reaction mechanism were determined. The obtained results indicated that the VUV treatment system shows the best performance among different treatment processes, leading to more than 40% acetone conversion at room temperature. Moreover, the addition of Ag/CeO2 photocatalysts to the VUV treatment process not only increases the acetone conversion up to 76% but also, by involving the catalytic ozonation as a participating acetone oxidation pathway, can eliminate the generated ozone during the treatment process. The results revealed that adding Ag to CeO2 photocatalyst under VUV irradiation oxidized the produced CO, significantly improving the reaction selectivity and leading the acetone degradation reactions to total oxidation level of up to 96%. The stability of the Ag/CeO2 photocatalysts under VUV irradiation was investigated, and an in-situ regeneration process was employed for suppressing the catalyst deactivation process. The durability tests showed more than 73% acetone oxidation even after three consecutive runs and 990 min irradiation.