文献类型：期刊文献

英文题名：High-resolution spectroscopy (XPS, 1H MAS solid-state NMR) and DFT investigations into Ti-modified Phillips CrOx/SiO2 catalysts

作者：Cheng, Ruihua[1]; Xu, Chen[1]; Liu, Zhen[1]; Dong, Qi[1]; He, Xuelian[1]; Fang, Yuwei[2]; Terano, Minoru[2]; Hu, Yatao[3]; Pullukat, Thomas J.[3]; Liu, Boping[1]

机构：[1] State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China; [2] School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan; [3] Research and Development Center, PQ Corporation, 280 Cedar Grove Road, Conshohocken, PA 19428-2240, United States

年份：2010

卷号：273

期号：2

起止页码：103

外文期刊名：Journal of Catalysis

收录：EI(收录号：20103313159155)

语种：英文

外文关键词：Density functional theory - Spectroscopic analysis - Catalysts - Ethylene - Photons - Light polarization - Molecular weight distribution - Nuclear magnetic resonance spectroscopy - Photoelectrons - Polymerization - Chromates

摘要：Ti-modified Phillips catalyst is a most important industrial catalyst widely used in ethylene polymerization, but the mechanism still remains mysterious. In this work, Ti-modified Phillips catalysts were characterized by high-resolution X-ray photoelectron spectroscopy (XPS) and 1H magic-angle-spin solid-state nuclear magnetic resonance (1H MAS solid-state NMR) combined with density functional investigations into the effects of Ti-modification on promotion of polymerization activity and regulation of microstructures of the polymer chains. XPS data revealed Ti-modification caused increase in electron-deficiency and photo-stability of the surface chromate species. 1H NMR provided the first direct evidence of surface residual Ti-OH groups. Modeling results rationalized well the effects of Ti-modification on promotion of polymerization activity, extension of molecular weight distribution (MWD) to lower MW region, improvement of the distribution of inserted co-monomer and enhancement of 2,1-insertion in regioselectivity of Phillips catalysts. It was the first time the Ti-modification on Phillips catalysts were theoretically elucidated. ? 2010 Elsevier Inc. All rights reserved.