The Influence of Metal Cations on Crystal Morphology of OFF Zeolite and Their Methanol-to-Olefins Performance
MA Duozheng, LIU Chuang, WANG Zhendong
State Key Laboratory of Green Chemical Engineering and Industrial Catalysis, SINOPEC (Shanghai) Research Institute of Petrochemical Technology Company Limited, Shanghai 201208, China
Abstract：The crystal size and shape of zeolites can have a significant impact on the results of catalytic reactions. In this study, hexamethyldiammonium hydroxide was used as the organic structure-directing agent (OSDA), and the morphology of the OFF zeolite was regulated by adding metal cations to the initial gel. The Mg-OFF (spindle-like), Li-OFF (needle-like), Rb-OFF (plate-like), Cs-OFF (blocky), and Zr-OFF (spherical) zeolites were successfully synthesized. The effects of different metal cations on the products were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption-desorption and NH3 temperature programmed desorption (NH3-TPD). Compared with the traditional hexagonal prism c-OFF zeolite (1.0 μm×5.0 μm), the addition of metal cations can significantly reduce the crystal size. The catalytic performance of the different morphologies zeolites was evaluated using methanol-to-olefins (MTO) as probe reaction. The results show that the Cs-OFF and Zr-OFF zeolite with a smaller length-to-diameter ratio have relatively longer reaction lifetime, while the Li-OFF and Rb-OFF zeolite with a higher length-to-diameter ratio have shorter reaction lifetime and an increase in the by-product C5+.
MA Duozheng,LIU Chuang,WANG Zhendong. The Influence of Metal Cations on Crystal Morphology of OFF Zeolite and Their Methanol-to-Olefins Performance[J]. Chemical Reaction Engineering and Technology, 2025, 41(3): 361-369.
