Study of the coordinative nature of alkylaluminum modified Phillips CrO_x/SiO_2 catalyst by multinuclear solid-state NMR

作     者：Zhang Qin-Hui Yan Fang Xia Wei Liu Chenguang 

作者机构：State Key Laboratory of Heavy Oil Processing College of Chemical Engineering China University of Petroleum 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2013年第10卷第4期

页      面：577-583页

核心收录：

学科分类：081702[工学-化学工艺] 081705[工学-工业催化] 08[工学] 0817[工学-化学工程与技术] 

基　　金：project sponsored by the Fundamental Research Funds for the Central Universities (No. 13CX05011A and R1304013A) 

主　　题：Phillips catalyst alkylaluminum ethylene polymerization solid-state NMR 

摘      要：Solid-state nuclear magnetic resonance spectroscopy was used to investigate the coordinative states of surface Al species on various alkylaluminum-modified Phillips CrOx/SiO2 *** alkylaluminum-modified Phillips CrOx/SiO2 catalysts were examined via ethylene homopolymerization.1H and 27Al magic angle spinning（MAS） nuclear magnetic resonance（NMR） spectra clearly demonstrated that the existing states of surface Al species in alkylaluminum-modified catalysts strongly depended on the type of alkylaluminum cocatalyst,concentration of alkylaluminum and the calcination temperature.1H MAS NMR spectra of alkylaluminum-modified Phillips CrOx/SiO2 catalysts,calcined at two different temperatures,exhibited similar trends in peak shift.1H spectra showed that with an increase of Al/Cr ratio and calcination temperature,the main peak shifted to high field,indicating that the dominant surface proton species changed from hydroxyl to ethoxyl and ethyl groups.27Al MAS NMR spectra showed the presence of three different coordination states（6-,5-,and 4-coordinated Al species） in the alkylaluminummodified Phillips *** comparison of different alkylaluminum cocatalysts,it was found that the reactivity of alkylaluminum modified Phillips catalyst decreased in the order of TEA〉DEAH〉*** amount of 4-coordinated Al species of Phillips catalysts modified by TEA,DEAE and DEAH also decreased in the order of TEA〉DEAH〉DEAE,indicating that the presence of 4-coordinated Al species is related to the polymerization activity.