氟硅酸铵改性对HMCM-22酸性及双功能催化剂催化合成二甲醚性能的影响  

Effects of Ammonium Hexafluorosilicate Modification on Acidity of HMCM-22 and Catalytic Performance of CuO-ZnO-Al_2O_3/HMCM-22 for Dimethyl Ether Synthesis

作　　者：毛东森[1] 夏建超[2] 陈庆龄[2] 卢冠忠[1] 

机构地区：[1]上海应用技术学院化学工程系应用催化研究所,上海200235 [2]中国石油化工股份有限公司上海石油化工研究院,上海201208

出　　处：《催化学报》2008年第12期1242-1246,共5页

基　　金：国家重点基础研究发展计划(973计划,2003CB615801);上海市自然科学基金(06ZR14080);上海市曙光计划(06SG35)

摘　　要：用氟硅酸铵对HMCM-22分子筛进行了改性处理,并采用氨程序升温脱附和吡啶吸附红外光谱法测定了其酸性.结果表明,随着氟硅酸铵处理温度的提高,HMCM-22分子筛的B酸和L酸中心的酸量均逐渐减少.以氟硅酸铵改性的HMCM-22分子筛为甲醇脱水活性组分与铜基甲醇合成活性组分(CuO-ZnO-Al2O3)组成双功能催化剂,在连续流动加压固定床反应器上考察了其对合成气直接制二甲醚反应的催化性能.结果表明,对HMCM-22分子筛在适当温度(45℃)下进行氟硅酸铵改性,可使反应产物中烃类和CO2副产物的选择性下降,使目的产物二甲醚的选择性显著升高.当氟硅酸铵处理温度过高(85℃)时,CO的转化率和二甲醚的选择性均大幅度降低。HMCM-22 zeolite was modified with ammonium hexafluorosilicate and characterized by temperature-programmed desorption of ammonia and pyridine adsorption infrared spectroscopy. The results indicated that the amounts of both Bronsted and Lewis acid sites were decreased with the increase of modification temperature. The direct synthesis of dimethyl ether （DME） from syngas was carried out in a pressurized fixed-bed reactor under cominuous flow conditions over a bifunctional catalyst composed of CuO-ZnO-Al2O3 and HMCM-22. The modification of HMCM-22 at proper temperature （45 12 ） decreased the selectivity for undesired hydrocarbons and CO2 and thus significantly enhanced the selectivity for DME. However, when the zeolite was treated at 85℃ , both the CO conversion and DME selectivity were decreased remarkably.

关 键 词：HMCM-22分子筛 氟硅酸铵 改性 甲醇脱水催化剂 双功能催化剂 合成气 二甲醚 

分 类 号：TQ223.24[化学工程—有机化工]