Beta分子筛中Al的分布和Brφnsted酸的酸性强度  

Location of Al and Acid Strength of Brφnsted Acid in Beta Zeolite

作　　者：孙秀良[1] 黄崇品[1] 张傑[1] 陈标华[1] 

机构地区：[1]北京化工大学化工资源有效利用国家重点实验室,北京100029

出　　处：《物理化学学报》2009年第6期1136-1142,共7页Acta Physico-Chimica Sinica

基　　金：国家重点基础研究发展规划(973)(2004CB217804);国家杰出青年科学基金(20625621)资助

摘　　要：基于量子化学中的密度泛函理论(DFT),研究了Beta分子筛中骨架Al在9个不同T位的分布和Brφnsted酸的分布及其强度.计算采用8T簇模型和B3LYP/6-31G(d,p)方法,得到了不同T位的Al/Si替代能、(Al,H)/Si替代能和质子亲和势,以及碱性探针分子NH3在Beta分子筛酸性位的吸附能.结果表明,骨架Al和Brφnsted酸优生位于Beta分子筛的T5和T6位;其中酸性最强的位置是Al5-O14-Si9,最弱的位置是Al7-O3-Si1.Density functional theory （DFT） was applied to study the distribution of framework aluminum atoms at nine inequivalent T sites and the acidity of Brφnsted acid sites in Beta zeolite. The calculation was carried out at B3LYP/6-31G （d,p） level based on the 8T cluster model According to the calculated AI/Si substitution energies, （Al, H）/Si substitution energies, proton affinities and the adsorption energies of ammonia （NH3）, we propose that the most favorable sites for A1 substitution and Brφnsted acid sites are at the T5 and T6 sites. The acidity of A15-O14-Si9 is the highest among the preferred Brφnsted acid sites and the A17-O3-Sil site is the lowest.

关 键 词：Beta分子筛 BRΦNSTED酸 密度泛函理论 

分 类 号：O643.36[理学—物理化学]