晶种辅助预晶化法合成纳米ZSM-5分子筛及其在丙烷芳构化反应中的应用  

Synthesis of nano ZSM-5 molecular sieve by seed-assisted and pre-crystallization and its application in aromatization of propane

作　　者：王晗斌 张鹏 杨帆 刘新辉 庄建国 赵溢涛 朱学栋[1] WANG Hanbin;ZHANG Peng;YANG Fan;LIU Xinhui;ZHUANG Jianguo;ZHAO Yitao;ZHU Xuedong(Engineering Research Center of Large Scale Reactor Engineering and Technology,Ministry of Education,School of Chemical Engineering,East China University of Science&Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化工学院大型工业反应器工程教育部工程技术研究中心,上海200237

出　　处：《低碳化学与化工》2024年第2期67-73,104,共8页Low-Carbon Chemistry and Chemical Engineering

基　　金：国家自然科学基金(21776076);中央高校基本科研业务费专项资金(JKA01211710)。

摘　　要：在丙烷芳构化反应中,常规分子筛催化剂易积炭失活,导致催化性能及使用寿命均不理想。采用全硅分子筛Silicalite-1(S-1)作为晶种,结合晶种法和预晶化法合成了纳米ZSM-5分子筛(ZSM-5-Nano)。采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和N2物理吸/脱附表征了ZSM-5-Nano的结构。结果表明,ZSM-5-Nano是由粒径为50 nm左右的小颗粒堆积而成的,其比表面积高达395 m^(2)/g,同时富含晶间介孔。将ZSM-5-Nano负载Zn后得到催化剂Zn-ZSM-5-Nano,然后在固定床反应器中评价了该催化剂在丙烷芳构化反应(n(N_(2)):n(C_(3)H_(8))=7:3、空速为3000 h^(-1)、反应温度为550℃)中的催化性能。结果表明,Zn/ZSM-5-Nano拥有相对温和的酸性质,在丙烷芳构化反应中表现出了良好的催化性能,5 h内的丙烷转化率和轻芳烃(苯、甲苯和二甲苯)选择性分别高达88.4%和86.7%,且在5 h内基本不失活,催化性能优于微米ZSM-5分子筛(水热法)负载Zn催化剂和纳米ZSM-5分子筛(预晶化法)负载Zn催化剂。构效分析结果表明,Zn/ZSM-5-Nano的形貌和酸性共同作用提升了其催化性能,更短的扩散距离和更温和的酸性有效延缓了积炭的生成。In the aromatization reaction of propane,the conventional molecular sieve catalyst is prone to carbon deposition and deactivation,resulting in unsatisfactory catalytic performance and service life.Nanometer ZSM-5 molecular sieve(ZSM-5-Nano)was synthesized with pure silica molecular sieve Silicalite-1(S-1)as seed by combination with seed method and pre-crystallization method.The structure of ZSM-5-Nano was characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD)and N_(2) physical adsorption/desorption.The results show that ZSM-5-Nano is composed of small particles with a particle size of about 50 nm,its specific surface area is up to 395 m^(2)/g,and it is rich in intergranular mesopores.The catalyst Zn-ZSM-5-Nano was prepared by loading Zn with ZSM-5-Nano,and then the catalytic performance of the catalyst for the aromatization reaction(n(N_(2)):n(C_(3)H_(8))=7:3,space velocity of 3000 h^(-1) and reaction temperature of 550℃)of propane was evaluated in a fixed bed reactor.The results show that Zn/ZSM-5-Nano has relatively mild acid properties,and shows good catalytic performance in the aromatization reaction of propane.The conversion rate of propane and the selectivity of light aromatics(benzene,toluene and xylene)within 5 h are as high as 88.4%and 86.7%,respectively,and the activity is stable within 5 h.The catalytic performance is better than that of the micrometer ZSM-5 molecular sieve(hydrothermal method)supported Zn catalyst and the nanometer ZSM-5 molecular sieve(pre-crystallization method)supported Zn catalyst.The results of structure activity analysis show that the better catalytic performance of Zn/ZSM-5-Nano is the result of the combination of morphology and acidity,and the shorter diffusion distance and milder acidity effectively delay the formation of carbon deposition.

关 键 词：丙烷芳构化 晶种辅助 预晶化法纳米 纳米ZSM-5分子筛 

分 类 号：TQ203.2[化学工程—有机化工]