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 CrO_x/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]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Japan Adv Inst Sci & Technol, Sch Mat Sci, Nomi, Ishikawa 9231292, Japan;[3]PQ Corp, Ctr Res & Dev, Conshohocken, PA 19428 USA

年份：2010

卷号：273

期号：2

起止页码：103

外文期刊名：JOURNAL OF CATALYSIS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000280658500003)】；

基金：The authors thank the financial support by Key Projects in the National Science & Technology Pillar Program during the 11th Five-Year Plan Period (2007BAE50B04) and National Natural Science Foundation of China (20774025), the research program of the State Key Laboratory of Chemical Engineering, Shanghai Pujiang Talent Plan Project (08PJ14032) and the Program of Introducing Talents of Discipline to Universities (B08021), and also the kind donation of the Ti-modified Phillips catalysts from PQ Corporation.

语种：英文

外文关键词：Phillips CrOx/SiO2 catalyst; Ti-modification; X-ray photoelectron spectroscopy; H-1 magic-angle-spin solid-state nuclear magnetic resonance; Density functional theory

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 H-1 magic-angle-spin solid-state nuclear magnetic resonance (H-1 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. H-1 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. (C) 2010 Elsevier Inc. All rights reserved.