摘要
富Ti的Ti-YNU-1分子筛的红外光谱中930 cm~(-1)特征峰属于一种新的骨架钛物种,而且表现出更高的催化活性。这个新型钛物种的结构以及催化作用机理尚不明确。本文应用密度泛函理论计算,研究了Ti-YNU-1分子筛上骨架钛物种的结构和振动光谱,考察了活性中心结构以及1-己烯环氧化反应的催化机理,并与Ti-MWW分子筛进行对比。所有计算在B3LYP/6-31G(d,p)理论水平进行。结果表明,在富Ti的Ti-YNU-1分子筛的红外光谱中930 cm~(-1)的Ti特征峰归属于Ti1OH(T6nest)或Ti6OH物种。在层间开放位点的钛氧活性中心上,1-己烯环氧化反应的活化能更低,表明Ti-YNU-1分子筛的活性高于Ti-MWW分子筛,与实验结果很好地吻合。
Density functional theory was used to study the microstructure,vibrational spectra of framework Ti species in Ti-YNU-1 zeolite.We also explored the structure of active centers and the mechanism of 1-hexene epoxidation in Ti-YNU-1 and compared with Ti-MWW zeolite.The results indicated that the Ti-specific peak at 930 cm~(-1) in the IR spectrum of Ti-rich Ti-YNU-1 is attributed to Ti1OH(T6nest) or Ti60 H species.The activation energy of1-hexene epoxidation at interlayer open site is lower,showing that Ti-YNU-1 is more active than Ti-MWW,which is in very good agreement with the experiment measurements.
引文
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