高硅分子筛ZSM-23的合成及表征

Synthesis and Characterization of ZSM-23 Zeolite with High Silica

采用静态水热晶化法以吡咯烷为模板剂,合成出结晶度良好的ZSM-23分子筛晶体.对合成条件的研究结果表明,合成的关键是避免ZSM-35分子筛的生成.当n(Si)/n(Al)=25～110,n(H20)/n(SiO2)=1.3～4.8,n(pyr.)/n(SiO2)=0.12～0.5时,均能稳定生成ZSM-23分子筛晶体.当n(Si)/n(Al)>110时,不能得到分子筛晶体;当n(Si)/n(Al)<25时,生成的是ZSM-35分子筛晶体.采用XRD,SEM,TG-DTA,FTIR等技术,对合成的ZSM-23分子筛晶体的形貌,以及影响分子筛合成的因素进行了详细的研究.

Pure and well crystallized zeolite ZSM-23 was synthesized under static hydrothermal crystallization condition using pyrrolidine as template. Under the conditions of n(Si)/n(Al) =25～110, n(H_2O) / n(SiO_2)=1.3～4.8, and n(pyr.) / n(SiO_2)= 0.12～0.5, the ZSM-23 was obtained as a pure phase. The investigation of the crystallization conditions indicates that the product obtained and its trans-crystllization depend on the Si/Al ratios of the gel system. When the Si/Al ratios equal to 25～110, the product obtained is ZSM-23, which may be trans-crystallized into ZSM-35 at a lower Si/Al ratio such as 20. When the Si/Al ratio is higher than 110, the zeolite crystal can not be obtained. The morphology of ZSM-23 and the roles of water? template and the effect of Si/Al ratios on acid property of ZSM-23 were studied by XRD, TEM, TG-DTA and FTIR techniques.