Synthesis of hierarchical MFI zeolite by interzeolite conversion of spent FAU zeolite for the methanol-to-olefins reaction

Developing a strategy for the resource utilization of spent zeolite catalysts is essential for addressing the environmental hazards of spent catalysts. In this study, the hierarchical ZSM-5 zeolite was synthesized through interzeolite conversion of spent Y zeolite catalyst in the absence of template. The synthesized ZSM-5 catalyst demonstrated excellent catalytic stability and propene selectivity in the MTO reaction, with a catalytic lifespan approximately twice as long as that of the conventional ZSM-5 catalyst. The results suggested that carbon deposited in spent Y zeolite serves as a hard template during the synthesis of ZSM-5, contributing to the formation of mesopores and inhibiting crystal growth. Furthermore, the existence of hierarchical pores enhanced product diffusion rates, preventing secondary reactions within the channels. This work offers a general and efficient approach for converting spent zeolite catalysts into more valuable hierarchical zeolites, thereby promoting the resource utilization of hazardous spent zeolite catalysts and mitigating their environmental impact.