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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/HZSM 5上脱水的反应机理
A series of MgO-modified HZSM 5 molecular sieves were prepared by impregnation method. The bifunctional catalyst was synthesized by using MgO / HZSM 5 as methanol dehydration catalyst and Cu ZnO Al 2 O 3 as methanol synthesis catalyst. The results showed that the DME modified HZSM 5 molecular sieve composition bifunctional catalyst, DME selectivity up to 68%, CO2 and hydrocarbons deputy The selectivity of the product was 30 2% and 0 4%, respectively. The selectivity to dimethyl ether from the unmodified HZSM 5 molecular sieve was only 491%. The selectivity of CO 2 and hydrocarbon by-products Respectively, up to 371% and 93% respectively.When the content of MgO is too high, the conversion of CO and the selectivity of DME decrease.According to the experimental results, the reaction mechanism of methanol dehydration on MgO / HZSM 5 is proposed