晶种法制备多级孔ZSM-5分子筛的研究
Study on synthesis of hierarchical ZSM-5 zeolite by seed method
韩文华 1洪鲁伟 2李滨 2周微 2刘冠锋 2王银斌2
作者信息
- 1. 中海油惠州石化有限公司,广东惠州 516086
- 2. 中海油天津化工研究设计院有限公司,天津 300131
- 折叠
摘要
以铝酸钠为铝源、硅溶胶为硅源、Silicalite-1(S-1)为晶种,引入碳酸铵作为助剂,采用晶种法制备多级孔纳米ZSM-5团簇分子筛,考察了碳酸铵加入量、晶种加入量、水硅比和晶化温度对多级孔ZSM-5分子筛物性的影响.X射线衍射(XRD)、扫描电子显微镜(SEM)和N2吸附-脱附表征结果表明:碳酸铵的加入降低了体系pH,减缓了分子筛成核速率,显著降低了ZSM-5分子筛的相对结晶度;当S-1加入量为5%～7%(质量分数)时,能够提高ZSM-5分子筛的比表面积和孔容;此外,水硅比对ZSM-5分子筛形貌影响显著,当水硅比为45时,能够合成出介孔分布更为集中的多级孔ZSM-5分子筛.由于多级孔纳米结构提高了活性位点与反应物的可接近性,同时降低了反应产物在孔道中停留时间,因此与分子筛ZSM-5-180相比,该分子筛在偏三甲苯与甲醇烷基化反应中表现出优异的稳定性及均四甲苯选择性.
Abstract
Hierarchical nano-sized ZSM-5 aggregate zeolite was synthesized by seed-assisted method with sodium alumi-nate as aluminum source,silica sol as silicon source,Silicalite-1(S-1)as seeds and ammonium carbonate as auxiliary agent.The effects of the amount of ammonium carbonate,the amount of seed,the H2O/SiO2 ratio and the crystallization tem-perature on the physical properties of the hierarchical ZSM-5 zeolite were investigated.The characterization results of X-ray diffraction(XRD),scanning electron microscopy(SEM),and N2 adsorption-desorption indicated that the addition of ammonium carbonate reduced the pH value of the system,which slowed down the nucleation rate of the zeolite,and significantly reduced the relative crystallinity(RC)of ZSM-5.S-1 could increase the specific surface area and pore volume of ZSM-5 zeolite when it was added at a dosage of 5%～7%(mass fraction).Furthermore,the H2O/SiO2 ratio had a significant effect on the morphology of ZSM-5 zeolite.The hierarchical ZSM-5 zeolite with more concentrated mesoporous distribution could be synthesized with H2O/SiO2 ratio of 45.Due to the improved accessibility of active centers and reac-tants,as well as the reduced residence time of reaction products in the pores,the zeolite exhibited excellent stability and se-lectivity for the alkylation of trimethylbenzene with methanol compared with the ZSM-5-180 zeolite.
关键词
晶种法/碳酸铵/多级孔/ZSM-5/烷基化Key words
seed-assisted method/ammonium carbonate/hierarchical/ZSM-5/alkylation引用本文复制引用
基金项目
中国海洋石油集团有限公司CCUS重大专项(KJGG-2022-12-CCUS-030403)
出版年
2024
NETL
NSTL
万方数据