Synthesis, structure, and acidic properties of MCM-41 functionalized with phosphate and titanium phosphate groups.
Synthesis, structure, and acidic properties of MCM-41 functionalized with phosphate and titanium phosphate groups.
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DOI：
10.1021/jp0580625
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发表时间：
2005-06
期刊：
影响因子：
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通讯作者：
T. Kovalchuk;H. Sfihi;A. Korchev;A. Kovalenko;V. G. Il’in;V. Zaitsev;J. Fraissard
中科院分区：
文献类型：
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作者：
T. Kovalchuk;H. Sfihi;A. Korchev;A. Kovalenko;V. G. Il’in;V. Zaitsev;J. Fraissard
介孔分子筛Si-MCM-41（纯硅质）和Ti-MCM-41（部分覆盖有TiO 2表面层）通过用POCl 3处理而用磷酸根基团官能化（分别表示为-MCM-41（P）和Ti-MCM-41（P））。使用TEM，X-射线衍射，和N2吸附，它表明，最初的六方结构，高比表面积，和孔隙率保留在功能化的材料，但不如在起始材料。1HMASNMR和31 PMASNMR分析表明，Si-MCM-41（P）表面由磷酸硅和焦磷酸硅组成。Ti-MCM-41（P）的分子筛还含有二氢钛、氢钛和焦磷酸钛，后者是主要的。吸附氨的Si-MCM-41（P）和Ti-MCM-41（P）的TPD表明，功能化导致中，强酸中心的创建。介孔结构与酸性的结合使得MCM-41被磷酸基团官能化，有望用作固体酸催化剂。
Mesoporous molecular sieves Si-MCM-41 (purely siliceous) and Ti-MCM-41 (partly covered with a surface layer of TiO2) were functionalized with phosphate groups by treatment with POCl3 (denoted -MCM-41(P)and Ti-MCM-41(P), respectively). With the use of TEM, X-ray diffraction, and N2 adsorption, it was shown that the initial hexagonal structure, the high specific surface area, and porosity are retained in the functionalized materials but are not as good as in the starting materials. 1H MAS NMR and 31P MAS NMR revealed that the surface of Si-MCM-41(P) consists of silicon phosphate and pyrophosphate species. That of Ti-MCM-41(P) additionally contains titanium dihydro-, hydro-, and pyrophosphate species, the latter being predominant. TPD of adsorbed ammonia for Si-MCM-41(P) and Ti-MCM-41(P) showed that functionalization leads to the creation of moderate and strong acid sites. A combination of mesoporous structure with acidic properties makes the MCM-41 functionalized with phosphate groups promising for use as solid acid catalysts.