CO2-Mediated Formation of Chiral Carbamates from meso-Epoxides via Polycarbonate Intermediates
发表时间：2019-03-12
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- 论文类型：
- 期刊论文
- 第一作者：
- Han, He
- 通讯作者：
- Guo, XW; Song, CS (reprint author), Dalian Univ Technol, Sch Chem Engn, State Key Lab Fine Chem, PSU DUT Joint Ctr Energy Res, Dalian 116024, Liaoning Provin, Peoples R China.
- 合写作者：
- Liu, Min,Nie, Xiaowa,Ding, Fanshu,Wang, Yiren,Li, Junjie,Guo, Xinwen,Song, Chunshan
- 发表时间：
- 2016-11-01
- 发表刊物：
- MICROPOROUS AND MESOPOROUS MATERIALS
- 收录刊物：
- SCIE、EI、Scopus
- 文献类型：
- J
- 卷号：
- 234
- 页面范围：
- 61-72
- ISSN号：
- 1387-1811
- 关键字：
- Toluene; Methanol; Styrene; Zeolite X; Alkali metal
- 摘要：
- The side-chain alkylation of toluene with methanol was investigated on a series of catalysts which were prepared by ion-exchange or subsequent impregnation of zeolie X with potassium hydroxide or cesium hydroxide aqueous solution. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, Ar physical adsorption-desorption, NH3 temperature-programmed desorption (TPD), CO2-TPD, pyridine adsorption Fourier-transform infrared (FT-IR) spectroscopy, FT-IR spectroscopy in O-H stretch region, thermogravimetric/differential thermal analysis, ultraviolet Raman spectroscopy, and X-ray photoelectron spectroscopy. It was found that alkali metal oxide played extremely important roles in the modification of catalysts and in the catalytic reaction pathway. Strong basic sites were formed by modification of basic zeolite X with alkali metal oxide. These basic sites promoted the dehydrogenation of methanol to formaldehyde which was recognized as the true alkylating agent in side-chain alkylation. Consequently, side-chain alkylation of toluene with formaldehyde was enhanced. As toluene was mainly adsorbed and activated on alkali metal cations bonded on the zeolite framework, the synergistic effects between alkali metal oxide and alkali metal cations were proposed. One of the possible reaction path ways for side-chain alkylation of toluene with methanol over basic zeolite was described. Alkali metal ion-exchanged zeolite X modified with alkali metal oxide demonstrated relatively high side-chain alkylation activity. However, the improvement of styrene selectivity faced with great challenges. (C) 2016 Elsevier Inc. All rights reserved.
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- 否
