Oxidation behavior and kinetics of representative VOCs emitted from petrochemical industry over CuCeO_x composite oxides

CuCeO_x composite catalysts were synthesized via coprecipitation (COP-CuCeO_x) and incipient impregnation (IMP-CuCeO_x) methods, respectively. The physicochemical properties of the samples were characterized by XRD, low-temperature N₂ sorption, H₂-TPR and O₂-TPD. The influences of reactant composition and concentration, reaction space velocity, O₂ content, H₂O concentration, and catalyst type on the oxidation behaviors of benzene, toluene, and n-hexane emitted from petrochemical industry were systematically investigated. In addition, the related kinetic parameters were model fitted. Compared with IMP-CuCeO_x, COP-CuCeO_x had well-dispersed active phase, better low-temperature reducibility, and more active surface oxygen species. The increase of reactant concentration was unfavorable for toluene oxidation, while the opposite phenomenon could be observed in n-hexane oxidation. The inlet concentration of benzene was irrelevant to its conversion under high oxidation rate. The introduction of benzene obviously inhibited the oxidation of toluene and n-hexane, while the presence of toluene had a positive effect on benzene conversion. The presence of n-hexane could promote the oxidation of toluene, while toluene had a negative influence on n-hexane oxidation. Both low space velocity and high oxygen concentration were beneficial for the oxidation process, and the variation of oxygen content had negligible effect on n-hexane and benzene oxidation. The presence of H₂O noticeably inhibited the oxidation of toluene, while significantly accelerated the oxidation procedure of benzene and n-hexane. COP-CuCeO_x had superior catalytic performance for toluene and benzene oxidation, while IMP-CuCeO_x showed higher n-hexane oxidation activity under dry condition. The oxidation behaviors under different conditions could be well fitted and predicted by the pseudo first-order kinetic model.