Oxidative gas phase carbonylation of methanol to dimethyl carbonate over chloride-free Cu-impregnated zeolite Y catalysts at elevated pressure
Oxidative gas phase carbonylation of methanol to dimethyl carbonate over chloride-free Cu-impregnated zeolite Y catalysts at elevated pressure
复制标题
DOI：
10.1016/j.apcatb.2006.11.015
复制
发表时间：
2007-05-11
影响因子：
22.1
通讯作者：
Fricke, R.
中科院分区：
文献类型：
--
作者：
Richter, M.;Fait, M. J. G.;Fricke, R.
用硝酸铜（II）溶液初湿浸渍Y型沸石并在650 ℃下惰性活化导致用于在气相中甲醇氧化羰基化成碳酸二甲酯的活性催化剂。在升高的压力（0.4- 1.6MPa）下测量活性，进料组成为CO/MeOH/O-2 = 40/20/6- 1.5vol. %（通过N-2平衡）在负载有10-17 wt.%铜可以表明，在650 ℃下的惰性活化提高了活性，并且14-17重量%的Cu负载量可以提高活性。给出了最好的表现。结合XRD、TEM、TPR和DRIFT表征发现，惰性活化引发了CuO晶体的分散、Cu ~（2+）自动还原为Cu ~+以及Cu ~（2+）在沸石超笼中的再分布和富集。发现进料的O-2含量控制碳酸二甲酯的选择性。在140-170 ℃的温度范围内，在1.5体积%的O-2含量下，实现了70-75%的碳酸二甲酯选择性。这使得碳酸二甲酯的时空产率高达632 g l（cat）（-1）h（-1），甲醇转化率为5- 12%。主要副产物二甲氧基甲烷的形成令人惊讶地受到CO的影响，这与所提出的反应途径不一致。提出了一种机制，包括形成表面碳酸盐结构作为共同的中间体。(c)2007年由Elsevier B. V.出版。
Incipient wetness impregnation of zeolite Y with copper(II) nitrate solution and inert activation at 650 degrees C led to active catalysts for the oxidative carbonylation of methanol to dimethyl carbonate in the gas phase. Activities were measured under elevated pressure (0.4-1.6 MPa) with feed compositions of CO/MeOH/O-2 = 40/20/6-1.5 vol.% (balanced by N-2) over zeolite Y loaded with 10-17 wt.% copper. It could be shown that inert activation at 650 degrees C enhanced the activity, and that Cu loading of 14-17 wt.% gave the best performance. By combined XRD, TEM, TPR and DRIFT characterization it was found that the inert activation initiated dispersion of crystalline CuO, auto-reduction of Cu2+ to Cu+ and redistribution of copper ions with enrichment inside the supercages of the zeolite. The O-2 content of the feed was found to control the selectivity to dimethyl carbonate. Dimethyl carbonate selectivities of 70-75% were achieved within the temperature range of 140-170 degrees C at an O-2 content of 1.5 vol.%. This allowed space-time yields of dimethyl carbonate up to 632 g l(cat)(-1) h(-1) at methanol conversions of 5-12%. Formation of the main side product, dimethoxy methane, was surprisingly affected by CO, which is not in line with suggested reaction pathways. A mechanism is proposed including formation of surface carbonate structures as common intermediate. (c) 2007 Published by Elsevier B.V.