以四丁基氢氧化铵为模板剂、正硅酸乙酯为硅源,采用变温晶化法制备了自柱撑型纳米分子筛。利用XRD、SEM、TEM、N₂物理吸附-脱附、NH₃-TPD等表征手段对模板剂添加量、分子筛的生长过程、硅铝摩尔比调变范围进行了系统考察。结果表明,80℃低温晶化72 h、170℃高温晶化3 h就可得到结晶度良好的自柱撑型纳米分子筛;低温晶化时间的延长,有利于自柱撑纳米结构的形成;随着模板剂与二氧化硅的摩尔比由0.2增加至0.5,自柱撑型纳米分子筛的分支程度明显变高;通过变温晶化法可制备出硅铝摩尔比为50~300的自柱撑型纳米分子筛。研究了不同硅铝摩尔比自柱撑型纳米分子筛在正庚烷裂解反应中的性能,结果表明,硅铝摩尔比为300的分子筛催化正庚烷裂解具有最高的丙烯与丁烯选择性;随着硅铝摩尔比的降低,催化剂的稳定性逐渐提高。

Self-pillared molecular sieve is synthesized via a temperature-variable crystallization method by using tetrabutylammonium hydroxide as template and ethyl orthosilicate as silicon source.XRD,SEM,TEM,N₂ physical adsorption-desorption,NH₃-TPD and other characterization methods are employed to systematically investigate the dosage of template,the growth process of molecular sieve and the varying range of Si/Al ratio.It is found from the study that self-pillared molecular sieve with a good crystallinity can be obtained by a 72-hour low temperature crystallization at 80℃ and a 3-hour high temperature crystallization at 170℃.A longer crystallization time at low temperature is conducive to the formation of self-pillared nanostructures.As the molar ratio of template to silica increases from 0.2 to 0.5,the branching degree of self-pillared nano molecular increases significantly.Self-pillared molecular sieve with a silicon-alumina ratio between 50 and 300 can be synthesized by a temperature-variable crystallization method.The performance of self-pillared molecular sieve with different Si/Al ratios in n-heptane cracking reaction is studied.Results show that the molecular sieve with a Si/Al ratio of 300 can lead to the highest propene and butene selectivity in n-heptane cracking.With the decrease of Si/Al ratio,the stability of the catalyst improves gradually.

陈毅(1997-),男,硕士研究生,研究方向为分子筛合成、改性及工业化应用,cy3011056538@163.com。