Enhancement in microporosity and catalytic activity on grafting silica and organosilica moieties in lamellar titanium phosphate framework
Enhancement in microporosity and catalytic activity on grafting silica and organosilica moieties in lamellar titanium phosphate framework
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DOI：
10.1016/j.apcata.2008.03.018
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发表时间：
2008-07
影响因子：
5.5
通讯作者：
K. Sarkar;Mahasweta Nandi;A. Bhaumik
中科院分区：
文献类型：
--
作者：
K. Sarkar;Mahasweta Nandi;A. Bhaumik
在水热条件下，在酸性条件下，不需要任何模板剂或结构导向剂的辅助，合成了新型硅接枝层状半晶磷酸钛（sc-TiOP）、硅钛磷酸盐（STP）和有机-无机杂化硅钛磷酸盐（HSTP）。通过元素分析、粉末XRD、场发射扫描电子显微镜（FE-SEM）、透射电子显微镜（TEM）、N2吸附和光谱研究对材料进行了表征。N2吸附研究表明，当Si原子被纳入层状磷酸钛骨架时，表面积显着增加。在HSTP材料中接枝有机硅烷部分，表面积进一步提高。傅立叶变换红外光谱（FT IR）、紫外-可见光谱（UV-vis）和X射线光电子能谱（XPS）分析结果表明，这些新型微孔材料中存在Si-O-P、Ti-O-Si键和Ti（IV）的八面体配位。Si和Si-CH_2CH_2-Si接枝的材料对苯乙烯、α-甲基苯乙烯、环己烯和丙烯酸的液相部分氧化反应具有显著的催化活性。在氨水和稀H_2O_2水溶液存在下，与无硅的sc-TiOP类似物相比，这些材料在环己酮氨肟化反应中表现出优异的催化活性和选择性。
New silica-grafted analogs of lamellar semicrystalline titanium phosphate (sc-TiOP), silicotitanium phosphate (STP) and organic–inorganic hybrid silicotitanium phosphate (HSTP) have been synthesized under hydrothermal condition without the assistance of any template or structure-directing agent under acidic pH conditions. These materials were characterized by elemental analysis, powder XRD, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N2sorption and spectroscopic studies. N2adsorption studies revealed that the surface area increased significantly when the Si atoms were incorporated into the layered titanium phosphate framework. The surface area improves further with the grafting of organosilane moiety in HSTP material. Fourier-transformed infrared (FT IR), UV–vis and X-ray photoelectron spectroscopic (XPS) results suggested the presence of Si–O–P, Ti–O–Si bonds and octahedral coordination of Ti(IV) in these novel microporous materials. Si- and Si–CH2CH2–Si-grafted materials showed considerable enhancement in catalytic activity towards the liquid phase partial oxidation of styrene, α-methyl styrene, cyclohexene and acrylic acid using dilute H2O2as an oxidant. These materials also showed excellent catalytic activity and selectivity in ammoximation of cyclohexanone to cyclohexanone oxime in the presence of aqueous ammonia and dilute aqueous H2O2with reference to the silica-free sc-TiOP analogue.