运用密度泛函理论研究了B和Ga改性的ZSM-5分子筛催化基于芳烃侧链机理的MTO(methanol to olefin)反应,并与未改性的ZSM-5催化反应的结果进行了比较。结果表明:在三个分子筛(ZSM-5,B-ZSM-5和Ga-ZSM-5)中,对于整个基于芳烃的侧链机理,决...运用密度泛函理论研究了B和Ga改性的ZSM-5分子筛催化基于芳烃侧链机理的MTO(methanol to olefin)反应,并与未改性的ZSM-5催化反应的结果进行了比较。结果表明:在三个分子筛(ZSM-5,B-ZSM-5和Ga-ZSM-5)中,对于整个基于芳烃的侧链机理,决速步骤是对二甲苯的甲基化。从中间体M5开始,生成乙烯的决速步骤都是乙烯的消除;而对于生成丙烯,其决速步骤都是3,3-二甲基-6-亚乙基-1,4-环己二烯的甲基化。与未改性的ZSM-5相比,B改性的ZSM-5分子筛尽管反应活性降低了,但使得甲醇制乙烯的选择性高于制丙烯的选择性,而Ga改性的ZSM-5分子筛对甲醇制乙烯和丙烯的选择性和活性影响都不大。展开更多
采用水热合成法辅加磁场成功制备了b、c复合轴向型ZSM-5分子筛,考察了磁感线分布、磁场强度和作用时间对ZSM-5分子筛结构和甲醇芳构化反应催化性能的影响。结果表明,磁场强度和作用时间可以精密调控材料的孔径分布;磁场强度47.1 m T,平...采用水热合成法辅加磁场成功制备了b、c复合轴向型ZSM-5分子筛,考察了磁感线分布、磁场强度和作用时间对ZSM-5分子筛结构和甲醇芳构化反应催化性能的影响。结果表明,磁场强度和作用时间可以精密调控材料的孔径分布;磁场强度47.1 m T,平行磁感线位置下作用5 h,合成材料具有b、c-复合轴取向结构,介孔的比表面积和孔容比分别达到67%和78%。相比常规ZSM-5,新材料具有更高的催化稳定性,反应20 h后的甲醇转化率和芳烃收率保持在98%和36%以上。展开更多
Continuous and perfect single-layer B-Al-ZSM-5 zeolite membranes with c-axis orientation, self-transformation from B-containing porous gla ss disks w ith rough and uneven surfaces full of pits, have been in-situ prepa...Continuous and perfect single-layer B-Al-ZSM-5 zeolite membranes with c-axis orientation, self-transformation from B-containing porous gla ss disks w ith rough and uneven surfaces full of pits, have been in-situ prepared on the su bstrates surfaces in a mixed vapor of ethylenediamine, tri-n-propylamine a nd H 2O . The thickness of the membranes is ca. 60 μm. Under the conditions of 20 ℃ and 0.1 MPa pressure difference, the permeabilities of H 2, O 2 and N 2 thro ugh the calcined B-Al-ZSM-5 zeolite membranes are 2 298×10 -8 , 1 176 ×10 -8 and 1 368×10 -9 mol/(m 2·s·Pa), respectively. The calculated values of ideal se lectivities of H 2 an d O 2 over N 2 are 16 8 and 8 60, respectively. The data indicate that the c alcin ed zeolite membranes are non-pinhole, non-crack, continuous and perfect.展开更多
文摘运用密度泛函理论研究了B和Ga改性的ZSM-5分子筛催化基于芳烃侧链机理的MTO(methanol to olefin)反应,并与未改性的ZSM-5催化反应的结果进行了比较。结果表明:在三个分子筛(ZSM-5,B-ZSM-5和Ga-ZSM-5)中,对于整个基于芳烃的侧链机理,决速步骤是对二甲苯的甲基化。从中间体M5开始,生成乙烯的决速步骤都是乙烯的消除;而对于生成丙烯,其决速步骤都是3,3-二甲基-6-亚乙基-1,4-环己二烯的甲基化。与未改性的ZSM-5相比,B改性的ZSM-5分子筛尽管反应活性降低了,但使得甲醇制乙烯的选择性高于制丙烯的选择性,而Ga改性的ZSM-5分子筛对甲醇制乙烯和丙烯的选择性和活性影响都不大。
文摘采用水热合成法辅加磁场成功制备了b、c复合轴向型ZSM-5分子筛,考察了磁感线分布、磁场强度和作用时间对ZSM-5分子筛结构和甲醇芳构化反应催化性能的影响。结果表明,磁场强度和作用时间可以精密调控材料的孔径分布;磁场强度47.1 m T,平行磁感线位置下作用5 h,合成材料具有b、c-复合轴取向结构,介孔的比表面积和孔容比分别达到67%和78%。相比常规ZSM-5,新材料具有更高的催化稳定性,反应20 h后的甲醇转化率和芳烃收率保持在98%和36%以上。
文摘Continuous and perfect single-layer B-Al-ZSM-5 zeolite membranes with c-axis orientation, self-transformation from B-containing porous gla ss disks w ith rough and uneven surfaces full of pits, have been in-situ prepared on the su bstrates surfaces in a mixed vapor of ethylenediamine, tri-n-propylamine a nd H 2O . The thickness of the membranes is ca. 60 μm. Under the conditions of 20 ℃ and 0.1 MPa pressure difference, the permeabilities of H 2, O 2 and N 2 thro ugh the calcined B-Al-ZSM-5 zeolite membranes are 2 298×10 -8 , 1 176 ×10 -8 and 1 368×10 -9 mol/(m 2·s·Pa), respectively. The calculated values of ideal se lectivities of H 2 an d O 2 over N 2 are 16 8 and 8 60, respectively. The data indicate that the c alcin ed zeolite membranes are non-pinhole, non-crack, continuous and perfect.
