Abstract: Propane dehydrogenation (PDH) is regarded as one of the most promising routes for propylene production owing to its advantages of high product purity and low separation energy consumption. Developing efficient and stable catalytic materials is crucial for improving PDH performance. In this work, the controllable synthesis and thermal stability of pure-silica ZSM-12 zeolite with a twelve-membered-ring pore structure were systematically investigated. By tuning the gel composition and crystallization conditions, the optimized synthetic parameters for ZSM-12 zeolite were established.In addition, the NH4+-exchanged ZSM-12 zeolite retains high crystallinity even after calcination at 1100 °C, demonstrating excellent thermal stability. On this basis, highly dispersed Co catalysts encapsulated in ZSM-12 zeolite was successfully constructed via a ligand-protected in situ synthesis strategy. The catalyst exhibited excellent catalytic performance in PDH at 550 °C, achieving a propylene formation rate of 16.4 mmolC3H6 gcat-1 h-1. Moreover, after a long-term reaction of 1600 min, its activity could be nearly restored to the initial level through regeneration, indicating good structural stability and regenerability. This study provides useful guidance for the design and preparation of pure silica large-pore zeolite and the development of efficient and stable PDH catalysts.

Key words: ZSM-12 zeolite, Thermal stability, Metal loading, Propane dehydrogenation, Light olefins