Synthesis and Methanol to Propylene Properties of Flowerlike Spheroidal Morphology Hierarchical ZSM-5
TONG Weiyi1, SONG Jiaqing2, ZHAO Yu1
1. State Key Laboratory of Green Chemical Engineering and Industrial Catalysis, Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208, China;
2. State Key Laboratory of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China
Abstract：In order to study the selectivity of ZSM-5 in methanol to olefins reaction, the core-shell structure, ordered hierarchical porous and flowerlike spheroidal morphology ZSM-5 samples, were obtained by post-treatment modification and controllable synthesis methods. The SiO2/Al2O3 ratio of the samples was similar, and all with high crystallinity. Compare with the conventional ZSM-5 sample, the selectivity of olefins could increased in methanol to propylene (MTP) reaction. Among the samples, Spheroidal morphology hierarchical ZSM-5 (S-HP) was synthesized by the combination of additives (urea and ammonium fluoride), and self-assembled to form uniform flowerlike spheroid morphology with the size of 200-500 nm. N2 adsorption and desorption data showed that S-HP sample had the largest mesoporous volume and average pore size, in the case of small external specific surface area, the special hierarchical porous and efficient matching of micro and mesoporous, which was conducive to mass transfer and diffusion. Meanwhile, the NH3 temperature programmed desorption (NH3-TPD) characterization showed the S-HP, with especially close desorption peaks, and the active sites of medium strong acid were significantly enhanced, which provided excellent active adsorption sites for MTP reaction. In the MTP reaction evaluation, S-HP compared with the conventional ZSM-5, the selectivity of propylene and ethylene increased from 11% and 9% to 30% and 15% respectively, and the selectivity of alkanes (methane, ethane and propane) decreased from 13.5%, 3% and 25.5% to 3%, 0.3% and 5.5% respectively, which significantly suppressed the hydrogen transfer reaction, S-HP showed the best reaction stability. The results showed that the selectivity and stability of MTP reaction were affected by the crystal structure and acid distribution of ZSM-5 zeolites.
TONG Weiyi1,SONG Jiaqing2,ZHAO Yu1. Synthesis and Methanol to Propylene Properties of Flowerlike Spheroidal Morphology Hierarchical ZSM-5[J]. Chemical Reaction Engineering and Technology, 2021, 37(6): 505-512.
