分子筛的晶体尺寸和形貌会对催化反应结果产生较大影响。本研究以氢氧化六甲双铵为有机模板剂，通过在初始凝胶中加入金属阳离子的策略调节OFF分子筛形貌，成功合成了c-OFF（六棱柱）、Mg-OFF（纺锤体）、Li-OFF（针棒状）、Rb-OFF（板状）、Cs-OFF（墩状）、Zr-OFF（椭球体）分子筛，并采用X射线衍射（XRD）、扫描电子显微镜（SEM）、N2吸附-脱附和氨气程序升温脱附（NH3-TPD）等表征手段考察了不同金属阳离子对产物的影响。与传统六棱柱c-OFF分子筛（1.0 μm×5.0 μm）相比，金属阳离子的加入可显著降低晶粒尺寸。以甲醇制烯烃（MTO）为探针反应，对合成的不同形貌OFF分子筛催化性能进行评价，结果表明具有较小长径比的Cs-OFF和Zr-OFF分子筛寿命相对较长，而具有较高长径比的Li-OFF和Rb-OFF分子筛寿命短且副产物C5+增多。"/>
The Influence of Metal Cations on Crystal Morphology of OFF Zeolite and Their Methanol-to-Olefins Performance
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.
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.
