Synergistic effect in bimetal Cr-Pt/ZSM-5 catalysts with high activity for CVOCs low-temperature removal

A series of Cr-Pt/ZSM-5 catalysts (0.5 wt% Pt) with various doping amounts of Cr species were prepared to investigate the synergy effect of MOx and ZSM-5 zeolites with micro-mesoporous structure on the oxidation performance of CVOCs low-temperature removal. The results indicate that the strong interaction between Pt and Cr species can be promoted by the doping of appropriate amount of Cr species, which is beneficial for the formation of more Cr6+ species and acid sites (especially for the strong acid sites). The synergistic effect of strong oxidizing sites (Cr6+/Pt species) and abundant acid sites (ZSM-5) is in favor of the dechlorination of DCE as well as the deep oxidation of intermediate products and by-products. Among these catalysts, the 10%Cr-Pt/ZSM-5 catalyst possesses the greatest oxidation activity for 1,2-dichloroethane (DCE) degradation with the T90% value as low as 255 °C, and also possesses excellent durability and catalytic activity for other non-chlorinated VOCs degradation. However, the structure of ZSM-5 zeolites is partly destroyed by the introduction of excess Cr species and the serious agglomeration of Cr species also occurs, which would weaken the interaction between Cr/Pt species and ZSM-5, resulting in a significant decline in its Cr6+ species and strong acid sites.