Silylation of [Nb]-MCM-41 as an efficient tool to improve epoxidation activity and selectivity
Silylation of [Nb]-MCM-41 as an efficient tool to improve epoxidation activity and selectivity
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DOI：
10.1016/j.jcat.2006.07.002
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发表时间：
2006-10-01
影响因子：
7.3
通讯作者：
Schuchardt, U.
中科院分区：
文献类型：
--
作者：
Gallo, J. M. R.;Pastore, H. O.;Schuchardt, U.
在室温下合成了有序的[Nb]-MCM-41，样品中几乎所有的铌都被取代到硅骨架中。该材料经煅烧后用六甲基二矽氮烷（HMDS）进行硅化。采用x射线衍射（XRD）、紫外-可见漫反射、电感耦合等离子体发射（ICP-OES）、红外光谱（FTIR）、低温N-2吸附、热重（TG）和Si-29魔角纺丝核磁共振（NMR-MAS）对煅烧和硅化材料进行了表征。以这些材料为催化剂，以过氧化叔丁基（TBHP）和70%的双氧水为氧化剂，对顺式环烯进行了环氧化反应，验证了硅基化对活性和选择性的影响。结果表明，硅氧烷化后的材料对两种氧化剂均具有较高的反应活性，在三必和必特条件下反应48 h可达到62%的转化率和94%的选择性，在双氧水条件下反应5 h可达到13%的转化率和80%的选择性。(c) 2006爱思唯尔公司版权所有。
Well-ordered [Nb]-MCM-41 was synthesized at room temperature with essentially all niobium present in the sample substituted into the silica framework. The material was calcined and then silylated using hexamethyldisilazane (HMDS). Both calcined and silylated materials were characterized by X-ray diffraction (XRD), diffuse reflectance UV-vis, inductively coupled plasma emission (ICP-OES), infrared spectroscopy (FTIR), N-2 adsorption at low temperatures, thermogravimetry (TG), and nuclear magnetic resonance of Si-29 with magic-angle spinning (NMR-MAS). The materials were used as catalysts in the epoxidation of cis-cyclooctene with tert-butyl hydroperoxide (TBHP) and 70 wt% aqueous hydrogen peroxide as oxidants, to verify the influence of the silylation on the activity and selectivity. It was observed that the silylated material was more active for both oxidants, reaching 62% conversion and 94% selectivity after 48 h with TBHP and 13% conversion and 80% selectivity after 5 h with aqueous hydrogen peroxide. (c) 2006 Elsevier Inc. All rights reserved.