甲醇气相脱水合成二甲醚用固体酸催化剂的研究

SOLID-ACID CATALYSTS FOR VAPOR PHASE DEHYDRATION OF METHANOL TO DIMETHYL ETHER

研究了耐温阳离子交换树脂、γ-氧化铝、分子筛等固体酸催化剂对甲醇气相脱水制二甲醚反应的催化性能,酸碱滴定、氨程序升温脱附、X射线衍射、热重-差热分析对催化剂样进行了表征。结果表明,达到相同的甲醇转化率,催化反应温度顺序为:t(γ-氧化铝)>t(树脂)>t(分子筛)。以耐温阳离子交换树脂为催化剂,甲醇转化率低于70%,当反应温度高于190℃时树脂很快失活;以γ-氧化铝为催化剂,在280～380℃之间,甲醇转化率高于80%,当温度为365℃时寿命大于500 h;以分子筛为催化剂,在200～280℃之间,甲醇转化率高于85%,分子筛易积碳失活。

The catalytic conversion of methanol to dimethyl ether （DME） was studied over a series of solid-acid catalysts, such as cationic resin , γ-alumina （γ-A12 03 ） and A zeolite. The samples were characterized by acid-base titration, temperature-programmed desorption （TPD） of ammonia, X-ray dif- fraction （XRD） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results indi- cated that to achieve the same conversion of methanol, reaction temperature decreased in the order of γ-Al2O3 〉cationic resin〉zeolite. The conversion of methanol on the cationic resin was below 70% and the cationic resin deactivated rapidly when the temperature was above 190 ℃. While on γ-A1203 cata- lyst,the conversion was above 80% in a wide range of temperatures （280 - 380 ℃） and the lifetime was more than 500 h at 365 ℃. On the zeolite catalyst,the conversion was above 85% when the tem- perature was between 200 and 280 ℃ and the catalyst deactivated with coking.