表征Y分子筛Brnsted酸中心强度的结构参数  

The Structure Parameters for Brnsted Acid Site Strength of Y Zeolite

作　　者：袁帅[1] 龙军[1] 赵毅[1] 田辉平[1] 刘宇键[1] 许昀[1] 代振宇[1] YUAN Shuai LONG Jun ZHAO Yi TIAN Huiping LIU Yujian XU Yun DAI Zhenyu(Research Institute of Petroleum Proccessing, SINOPEC, Beijing 100083, China)

机构地区：[1]中国石化石油化工科学研究院,北京100083

出　　处：《石油学报（石油加工）》2016年第6期1083-1089,共7页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家自然科学基金项目(U1463209)资助

摘　　要：采用量子力学方法研究了具有不同Brnsted酸强度的Y分子筛酸中心的结构特性,计算了O—H键长(dO—H)、H的Mulliken电荷(qH)、O—H伸缩振动频率(νO—H)、∠Si—O—Al、分子轨道能量等结构参数,并探讨了这些结构参数与分子筛酸强度的对应关系。研究表明,dO—H、qH、νO—H、∠Si—O—Al与分子筛Brnsted酸强度并不呈严格的对应关系,而酸性羟基O—H的反键轨道能量(EO—H*)与酸强度存在良好的对应关系,EO—H*越低,Brnsted酸性越强。因为EO—H*越低,O—H反键轨道越容易被电子填充;反键轨道被电子填充后,体系能量升高,O—H键越容易被破坏,越容易给出H+,从而Brnsted酸性越强。因此,提出可以用EO—H*表征Y分子筛Brnsted酸强度,补充和完善了表征分子筛酸强度的结构参数。The quantum mechanics method was applied to investigate the structure characteristics of Y zeolite with different Brnsted acid strength.The structural parameters,such as O—H bond distance（dO—H）,H Mulliken charge（qH）,O—H stretching vibration frequency（νO—H）,Si—O—Al angle and molecular orbital energy,were calculated.The relationship between these structural parameters and Brnsted acid strength was discussed.The results showed that there were poor correlations between qH,dO—H,νO—Hor Si—O—Al angle and B-acidity,however,there was a better correlation between anti-bonding orbita energy（EO—H＊）and B-acidity.The lower the EO—H＊,the stronger the B-acidity.An anti-bonding orbit with lower EO—H＊was more easily filled with electron,due to which the energy of the system would rise up to cause the O—H bond broken to give H＋,thus the B-acidity would be stronger.On this basis,EO—H＊was put forward to characterize Brnsted acid strength of Y zeolite,which would be a good complement to the structure parameters for acid site strength of Y zeolite.

关 键 词：分子筛 酸强度 结构参数 分子轨道能量 

分 类 号：O641[理学—物理化学]