Niu Xianjun, Bai Yang, Du Yi-En, Qi Hongxue, Chen Yongqiang
Department of Chemistry and Chemical Engineering, Jinzhong University, Jinzhong, Shanxi 030619, People's Republic of China.
R Soc Open Sci. 2022 Mar 23;9(3):211284. doi: 10.1098/rsos.211284. eCollection 2022 Mar.
ZSM-5 zeolites were hydrothermally synthesized with commercial silica sol, and the crystal size was controlled by adding silicalite-1 seed in the synthetic system. The crystal size of ZSM-5 was affected by the crystallization time of seed, seed content and seed size. ZSM-5 zeolites with controllable particle size in the range of 200-2200 nm could be obtained. The prepared samples with different particle sizes were used for the reaction of methanol conversion to aromatics (MTA). The results suggested that the HZSM-5 catalyst with small crystal size showed much longer catalyst lifetime and higher selectivity for C hydrocarbons and aromatics, especially C aromatics in the MTA reaction. Moreover, the introduction of zinc (Zn) into the HZSM-5 zeolites can considerably promote the selectivity to aromatics in the products. Zn modified HZSM-5 zeolites with different Zn loading amounts were prepared by the incipient wetness impregnation method, and the highest aromatics selectivity was obtained when the Zn loading was 1.0%. The improvement of methanol aromatization was ascribed to the synergistic effect of Brønsted acid sites and the newly formed Zn-Lewis acid sites.
采用市售硅溶胶水热合成ZSM-5沸石，并通过在合成体系中添加Silicalite-1晶种来控制晶体尺寸。ZSM-5的晶体尺寸受晶种的晶化时间、晶种含量和晶种尺寸的影响。可获得粒径在200-2200nm范围内可控的ZSM-5沸石。将制备的不同粒径的样品用于甲醇制芳烃（MTA）反应。结果表明，小晶体尺寸的HZSM-5催化剂在MTA反应中显示出更长的催化剂寿命以及对C烃和芳烃，尤其是C芳烃更高的选择性。此外，将锌（Zn）引入HZSM-5沸石中可显著提高产物中芳烃的选择性。采用初湿浸渍法制备了不同锌负载量的Zn改性HZSM-5沸石，当锌负载量为1.0%时，芳烃选择性最高。甲醇芳构化的改善归因于布朗斯台德酸位点和新形成的Zn-路易斯酸位点的协同作用。
