镁改性HZSM-5对Cu-ZnO-Al2_O_3/HZSM-5催化合成气直接制二甲醚反应的影响  

Effect of Mg-Modified HZSM-5 on Catalytic Performance of Cu-ZnO-Al_2O_3/HZSM-5 for Direct Synthesis of Dimethyl Ether from Syngas

作　　者：毛东森[1] 张斌[1] 宋庆英[1] 杨为民[1] 陈庆龄[1] 

机构地区：[1]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》2005年第5期365-370,共6页

基　　金：国家重点基础研究发展规划项目 (973计划 ) (2 0 0 3CB615 80 1);中国石油化工股份有限公司科技发展基金资助项目(2 0 0 0 0 2 )

摘　　要：采用浸渍法制备了一系列MgO改性的HZSM 5分子筛,并以MgO/HZSM 5为甲醇脱水催化剂与Cu ZnO Al2 O3 甲醇合成催化剂组成双功能催化剂,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,以适量MgO改性的HZSM 5分子筛组成的双功能催化剂上,二甲醚选择性可高达6 4 8% ,CO2 和烃类副产物的选择性分别为30 2 %和0 4 % ;由未改性的HZSM 5分子筛组成的双功能催化剂上,二甲醚选择性仅为4 9 1% ,CO2 和烃类副产物的选择性则分别高达37 1%和9 3% .当MgO含量过高时,则CO转化率和二甲醚选择性均降低.根据实验结果,提出了甲醇在MgO/HZSMA series of HZSM-5 zeolites modified by MgO were prepared by impregnation and characterized by N_2 adsorption, XRD, NH_3-TPD, CO_2-TPD and Py-IR methods. The direct synthesis of dimethyl ether (DME) from syngas was carried out over Cu-ZnO-Al_2O_3∥MgO/HZSM-5 under pressurized fixed-bed continuous flow conditions. The results indicated that the HZSM-5 modified with suitable amount of MgO could significantly enhance the selectivity for DME from 49 1% to 64 8%,and decreased the selectivity for the undesired hydrocarbons and CO_2 from 9 3% and 37 1% to 0 4% and 30 2%, respectively. However, when the MgO contents were higher than 5%, both the CO conversion and DME selectivity were decreased remarkably. A mechanism for methanol dehydration to DME involving both acidic and basic sites on MgO/HZSM-5 was proposed based on the experimental results.

关 键 词：合成气 二甲醚 双功能催化剂 甲醇脱水 甲醇合成 HZSM-5分子筛 氧化镁 铜 氧化锌 氧化铝 

分 类 号：O643.3[理学—物理化学]