NMR探针分子表征分子筛酸性的理论研究  

Characterization of Acidity of Zeolites by NMR Probe Molecules:A Theoretical Investigation

作　　者：邬忠琴[1] 郑安民[1] 杨俊[1] 邓风[1] 

机构地区：[1]波谱与原子分子物理国家重点实验室(中国科学院武汉物理与数学研究所)

出　　处：《波谱学杂志》2007年第4期501-509,共9页Chinese Journal of Magnetic Resonance

基　　金：国家自然科学基金资助项目(20425311)

摘　　要：用量子化学计算的方法,采用三甲基氧膦(TMPO)、吡啶和三甲基膦(TMP)3种探针分子,研究了工业上常用的3种分子筛H-Y、H-ZSM5、H-MOR的Brφnsted酸强度,讨论了这3种探针分子化学位移与Brφnsted相对酸强度的相关性,揭示了各种探针分子在表征Brφnsted酸性上的适用性.In this contribution, trimethylphosphine oxide （TMPO）, pyridine and trimethylphosphine （TMP） were selected as NMR probe molecules to study the acid strength of several industrially used zeolites （H-Y, H-ZSM5 and H-MOR） theoretically. The relationship between chemical shifts of these probe molecules and acid strength of zeolites was revealed. In the meanwhile, the applicability of probe molecules on the characterization of Bronsted acidity was discussed. Since the 1H, 15N and 31p chemical shift ranges of adsorbed DS-pyridine and TMP on the Bronsted acid sites in zeolites .were relatively very smaller （i. e. , δ 18.2 - 18.7, δ --191.0--186.9, 8 --8.7--3.5 for 1H, 15N and 31p, respectively）, they were only used to detect the existence of acidic protons in the zeolites. However, the 31p chemical shift range of adsorbed TMPO ranges from 3 62.8 to 8 90.5, and it may be expected that the adsorbed TMPO were very sensitive to measure solid acid strengths of the zeolites catalysts, compared with the 31p NMR of adsorbed TMPO.

关 键 词：核磁共振 化学位移 探针分子 量化计算 分子筛 吸附能 

分 类 号：O641.12[理学—物理化学]