氟化铵改性HUSY分子筛催化异丁烷/1-丁烯烷基化反应的研究

Alkylation of isobutane/1-butene over ammonium fluoride modified HUSY molecular sieves

利用氟化铵溶液对HUSY分子筛进行改性,采用扫描电镜、X射线衍射、N2吸附-脱附、NH3-程序升温脱附等方法对改性前后分子筛的形貌特征、晶相结构、孔道结构和酸性等进行表征,并考察了氟化铵处理时间对分子筛催化异丁烷/1-丁烯烷基化性能的影响。结果表明,氟化铵改性后分子筛的基本骨架结构得以保持,比表面积和微孔孔容减小,介孔孔容增加,中强酸与弱酸量的比值增大。HUSY经氟化铵溶液处理5 min后,其异丁烷/1-丁烯烷基化性能大幅度提高。

HUSY molecular sieves is treated by ammonium fluoride solution.The morphology,crystal structure,pore structure and acidity of the molecular sieves before and after modification are characterized by SEM,XRD,N2 adsorptiondesorption and NH3-TPD,respectively.Effects of treatment time on the performance of the modified molecular sieves in catalyzing alkylation of isobutane/1-butene are researched.It is indicated that fundamental framework of the molecular sieves modified by ammonium fluoride remains unchanged,while the pore structure and acidity are regulated.The modified molecular sieves have a smaller specific surface area and micropore pore volume,but a higher mesoporous volume than the parent molecular sieves.In addition,the ratio of medium-strong acid sites to weak acid sites is improved.HUSY molecular sieves that have been treated by ammonium fluoride for 5 minutes show a significantly improved performance in isobutane/1-butene alkylation.