Synthesis of ZSM-5/SAPO-34 Composite Molecular Sieves by Dry-Gel Conversion and Its Performance in Methanol-to-Aromatic Reaction
State Key Laboratory of Green Chemical Engineering and Industrial Catalysis, Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208, China
Abstract：ZSM-5/SAPO-34 composite molecular sieves were successfully synthesized by dry-gel conversion (DGC) method. The effects of synthesis conditions including dry-gel composition, dry-gel treatment conditions and crystallization time on the composite molecular sieves were studied. Methanol-to-Aromatic (MTA) probe reaction was used to test the catalytic performance of ZSM-5/SAPO-34 composite molecular sieves, which were prepared by DGC, embedding method (EBM) and mechanical blending (MEB) respectively. The results showed that the content of SAPO-34 in the ZSM-5/SAPO-34 composite molecular sieves could be modulated by adjusting dry-gel composition. Mild drying conditions of the dry-gel were in favor of the synthesis of ZSM-5/SAPO-34, and much too high temperature or too long drying time of the dry-gel would lead to the formation of ZSM-5/SAPO-5 composite molecular sieve. Proper prolonging of crystallization time was beneficial to improve the crystallinity of SAPO-34 zeolite in the composite molecular sieve, while after the crystallization time was prolonged to 96 h, the SAPO-34 would gradually be transformed into the SAPO-5. Compared to the EBM and MEB method, the aromatization activity of ZSM-5/SAPO-34 composite molecular sieves prepared by the DGC method was slightly lower, but the selectivity of the reaction product to xylene was more than 10% higher, which exhibited excellent shape-selectivity.
Chen Xiqiang. Synthesis of ZSM-5/SAPO-34 Composite Molecular Sieves by Dry-Gel Conversion and Its Performance in Methanol-to-Aromatic Reaction[J]. 化学反应工程与工艺, 2018, 34(1): 36-42.
