Synthesis of dimethyl carbonate from methanol and carbon dioxide in the presence of polyoxometalates under mild conditions
Synthesis of dimethyl carbonate from methanol and carbon dioxide in the presence of polyoxometalates under mild conditions
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DOI：
10.1016/s0926-860x(03)00400-9
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发表时间：
2003-12-30
影响因子：
5.5
通讯作者：
Wang, EB
中科院分区：
文献类型：
--
作者：
Jiang, CJ;Guo, YH;Wang, EB
采用溶胶-凝胶法制备了氧化锆负载Keggin单元12-钨磷酸/氧化锆（H3 PW 12 O 40/ZrO 2）。采用ICP-AES、IR、N2吸附、X射线衍射（XRD）和P-31魔角旋转NMR（MAS NMR）等方法对复合材料进行了表征，结果表明复合材料的Keggin结构在形成后保持完整，同时含有Bronsted酸中心和刘易斯酸中心。以H3 PW 12 O 40/ZrO 2为催化剂，甲醇和CO2为原料，在温和条件下选择性合成碳酸二甲酯（DMC）。考察了催化剂用量、反应温度和CO2压力等因素对DMC生成的影响，结果表明，催化剂活性强烈依赖于CO2压力。当反应在不同CO2压力下进行时，DMC合成在4和7.6 MPa下出现两个最大值，并且几乎没有检测到二甲醚和CO等副产物。H3 PW 12 O 40/ZrO 2复合材料中的B酸中心可用于甲醇活化和提高ZrO 2载体的催化活性。(C)2003 Elsevier B. V.保留所有权利。
Zirconia supported Keggin unit, 12-tungstophosphoric acid/zirconia (H3PW12O40/ZrO2), was prepared via sol-gel technique. As-synthesized composites were characterized by ICP-AES, IR spectroscopy, nitrogen adsorption determination, X-ray diffraction (XRD), and P-31 magic-angle spinning NMR spectroscopy (MAS NMR), indicating that the primary Keggin structure remained intact after formation of the composites, and that the composites contained both Bronsted and Lewis acid sites. Selective synthesis of dimethyl carbonate (DMC) from methanol and CO2 was investigated in the presence of H3PW12O40/ZrO2 catalysts under mild conditions. The effects such as the amount of catalysts, reaction temperature and CO2 pressure on the DMC formation were studied, indicting that the catalytic activity depend strongly on the CO2 pressure. When the reaction was carried out at various pressure of CO2, two maxima in DMC synthesis were observed at 4 and 7.6 MPa, and the byproducts such as dimethyl ether and CO were hardly detected. Bronsted acid sites in the H3PW12O40/ZrO2 composites can devote to methanol activation and to the enhancement of the catalytic activity of ZrO2 support. (C) 2003 Elsevier B.V. All rights reserved.