The role of copper chloride hydroxides in the oxidative carbonylation of methanol for dimethyl carbonate synthesis

Authors
Han, MSLee, BGAhn, BSKim, HSMoon, DJHong, SI
Issue Date
2003-09-01
Publisher
ELSEVIER
Citation
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL, v.203, no.1-2, pp.137 - 143
Abstract
Dimethyl carbonate (DMC) synthesis by oxidative carbonylation of methanol has been studied using vapor phase flow reaction system in the presence of CuCl2/NaOH/AC (AC, activated carbon) catalysts. A series of CuCl2/NaOH/AC catalysts have been prepared by the conventional impregnation method with varying the molar ratio of OH/Cu from 0.0 to 1.0. The catalytic activity Of CuCl2/NaOH/AC catalysts has been found to increase continuously with the increase of OH/Cu molar ratio as compared with CuCl2/AC catalyst. The morphological analysis by X-ray diffraction, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) has shown that the improved performance of CuCl2/NaOH/AC catalysts was closely related with the existence of copper chloride hydroxides (Cu-2(OH)(3)Cl). Two different crystal habits of Cu-2(OH)(3)Cl were observed in the catalyst surface based on the OH/Cu molar ratio. One is alpha-Cu-2(OH)(3)Cl (atacamite) which is orthorhombic, while the other is gamma-Cu-2(OH)(3)Cl (paratacamite) which is rhombohedral. The catalyst phase was revealed to change from alpha-Cu-2(OH)(3)Cl to gamma-Cu-2(OH)(3)Cl with the increase of OH/Cu molar ratio. The catalyst phase was alpha-Cu-2(OH)(3)Cl dominant at the molar ratio of OH/Cu = 0.5, while at the molar ratio of OH/Cu = 1.0, gamma-Cu-2(OH)(3)Cl dominant. The gamma-type catalyst was found to be more favorable to DMC synthesis than the alpha-type catalyst. The CO temperature-programmed desorption (TPD) experiments on the employed catalysts also strongly supported these observations. (C) 2003 Elsevier B.V. All rights reserved.
Keywords
CATALYTIC-PROPERTIES; DMC; PARATACAMITE; ATACAMITE; CUCL2; CATALYTIC-PROPERTIES; DMC; PARATACAMITE; ATACAMITE; CUCL2; dimethyl carbonate (DMC); oxidative carborylation of methanol; copper chloride hydroxides (Cu-2(OH)(3)Cl); atacamite; paratacamite
ISSN
1381-1169
URI
https://pubs.kist.re.kr/handle/201004/138241
DOI
10.1016/S1381-1169(03)00131-6
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KIST Article > 2003
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