One-step synthesis of dimethyl ether from the gas mixture containing CO₂ with high space velocity

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• 作者：Wei-Hsin Chen^a ; ^{weihsinchen@gmail.com} ; Bo-Jhih Lin^a ; How-Ming Lee^b ; Men-Han Huang^b
• 关键词：Dimethyl ether (DME) ; One-step and direct synthesis ; Bifunctional catalyst ; Cu&ndash ; ZnO&ndash ; Al2O3 catalyst and ZSM5 ; High space velocity ; Synthesis gas and CO2
• 刊名：Applied Energy
• 出版年：2012
• 期刊代码：2_03062619
• 类别：pw
• 出版时间：October, 2012
• 卷：98
• 期：Complete
• 页码：92-101
• 文件大小：1399 K

摘要

Dimethyl ether (DME) has been considered as a potential hydrogen carrier used in fuel cells; it can also be consumed as a diesel substitute or chemicals. To develop the technique of DME synthesis, a bifunctional Cu-ZnO-Al₂O₃/ZSM5 catalyst is prepared using a coprecipitation method. The reaction characteristics of DME synthesis from syngas at a high space velocity of 15,000 mL (g_cat h)^鈭? are investigated and the effects of reaction temperature, pressure, CO₂ concentration and ZSM5 amount on the synthesis are taken into account. The results suggest that an increase in CO₂ concentration in the feed gas substantially decreases the DME formation. The optimum reaction temperature always occurs at 225 掳C, regardless of what the pressure is. It is thus recognized that the DME synthesis is governed by two different mechanisms when the reaction temperature varies. At lower reaction temperatures (<225 掳C) the reaction is dominated by chemical kinetics, whereas thermodynamic equilibrium is the dominant mechanism as the reaction temperature is higher (>225 掳C). For the CO₂ content of 5 vol.%and the pressure of 40 atm, the maximum DME yield is 1.89 g (g_cat h)^鈭?. It is also found that 0.2 g of ZSM5 is sufficient to be blended with 1 g of the catalyst for DME synthesis.