H-Zr-MCM-48的合成及其正庚烷异构性能

通过水热法成功合成了锆掺杂的MCM-48(Zr-MCM-48)介孔材料,并用离子交换制得H-Zr-MCM-48催化剂。采用X射线衍射(XRD)、透射电镜(TEM)、氮气吸附-脱附等测试手段对样品进行表征。结果表明,所合成的Zr-MCM-48及H-Zr-MCM-48仍保持立方有序介孔结构,H-Zr-MCM-48催化剂的酸性及催化稳定性均有所提高。在正庚烷异构化探针反应中,同等反应条件(锆/硅摩尔比为0.02、反应温度为260℃、反应时间为130min)下,与Zr-MCM-48相比,H-Zr-MCM-48对正庚烷异构化反应的催化性能更好,转化率和选择性分别达到44.6%和94.5%。相对较高的多支链异庚烷产物比例表明,所合成的H-Zr-MCM-48催化剂对于烷烃异构化有良好的应用潜力。

Keggin Structure and Surface Acidity of 12-Phosphotungstic Acid Grafted Zr-MCM-48 Mesoporous Molecular Sieves

A zirconium modified MCM-48 mesoporous material was synthesized by surfactant-templated method. Surface grafting Zr-MCM-48 with tungstophosphoric acid led to a great enhancement of both the number of the Br?nsted acid sites and acidity strength in comparison with the bare support. At 100°C, the 30 wt% H3PW12O40/Zr-MCM-48 contained 174 μmol/g Br?nsted acid sites which were 14.5 times greater than that of Zr-MCM-48. The Keggin structure of the grafted heteropolyacid was rather stable after calcination at 400°C for 2 h, approximately 93.3% of Keggin structure in the dispersed heteropolyacid were remained without destruction but slightly distorted in some degree, as evidenced by FTIR characterization and 31P NMR-MAS analysis. This H3PW12O40/Zr-MCM-48 solid with three dimensional mesoporous system, large surface area and very strong Br?nsted acidity will be a promising catalyst for acid catalytic reactions.

锆掺杂MCM-48氧化硅的合成及其表征

以正硅酸乙酯为硅源,丙醇锆为锆源,十六烷基三甲基溴化铵为模板剂,通过水热合成法制备Zr-MCM-48介孔材料,提高材料的耐碱性能。利用XRD、N2吸附-脱附、XPS等手段对产物进行了结构和性能的分析。XRD检测显示当Zr/Si物质的量比小于0.1时,可以获得长程有序的MCM-48结构。N2吸附-脱附实验、XPS测试等证实Zr已经掺入MCM-48骨架中。稳定性实验结果表明Zr/Si物质的量比为0.03时,Zr-MCM-48材料的耐碱性能明显增强,进一步表明Zr掺入了MCM-48材料的骨架中。