Al-MCM-41分子筛的制备及其催化合成聚甲氧基二甲醚  

Preparation of Al-MCM-41 zeolite and its catalytic performance in the synthesis of polymethoxy dimethyl ether

作　　者：李国斌 徐彩霞 陈立宇[1] Li Guobin;Xu Caixia;Chen Liyu(School of Chemical Engineering,Northwest University,Xi’an Shaanxi 710069,China)

机构地区：[1]西北大学化工学院,陕西西安710069

出　　处：《石油化工》2021年第2期103-111,共9页Petrochemical Technology

摘　　要：采用水热合成法制备了不同Al含量的Al-MCM-41介孔分子筛,考察了分子筛催化甲醇和多聚甲醛合成聚甲氧基二甲醚(PODEn,n为聚合度)的性能;采用XRD、FTIR、N2吸附-脱附、ICP-OES、SEM、NH3-TPD等方法分析了分子筛的孔结构和酸性质对产物分布的影响,并对PODEn的合成工艺条件进行了优化。实验结果表明,制备的Al-MCM-41分子筛具有二维六方有序介孔结构;Al的掺入导致分子筛的比表面积、孔体积和孔径出现不同程度的减小,但有效提高了分子筛的中强酸量,进而促进高聚合度产物的生成;硅铝比为40的Al-MCM-41(40)分子筛的催化性能最优。PODEn最佳合成条件为:135℃、5 h、甲醇与多聚甲醛的摩尔比为1.5、催化剂的用量为2%(w),在此条件下,甲醇转化率达74.5%,PODE3~5选择性达31.3%。Al-MCM-41(40)分子筛重复使用5次仍具有较好的催化活性。Al-MCM-41 mesoporous zeolite with different Al contents were synthesized by the hydrothermal method.The catalytic performances of Al-MCM-41 zeolite in the synthesis of polyoxymethylene dimethyl ethers(PODEn,n represents degree of polymerization)with methanol and paraformaldehyde were investigated.XRD,FTIR,N2 adsorption-desorption,ICP-OES,SEM,and NH3-TPD techniques were used to analyze the pore structure and acid properties of Al-MCM-41,whose influence on the product distribution was discussed.The synthesis process conditions of PODEn were further optimized.The results show that the prepared Al-MCM-41 has an ordered two-dimensional hexagonal mesoporous structure.The doping of Al causes the specific surface area,pore volume and pore size of the zeolite decrease,while effectively increases the amount of medium-strong acid in zeolite which promotes the formation of high polymerization products.When the molar ratio of Si/Al is 40,the Al-MCM-41(40)zeolite shows the best catalytic performance.The optimal synthesis condition for PODEn is that the reaction temperature being 135℃,reaction time being 5 h,the ratio molar of methanol to paraformaldehyde being 1.5,and the amount of catalyst being 2%(w).Under the optimal condition,the conversion of methanol reaches 74.5%and the selectivity to PODE3-5 is up to 31.3%.Al-MCM-41(40)zeolite catalyst exhibited good catalytic activity after being reused for 5 times.

关 键 词：MCM-41分子筛 聚甲氧基二甲醚 铝改性 酸催化 多聚甲醛 

分 类 号：TQ426.94[化学工程]