Highly Active/Selective Heterogeneous Catalyst Co/Ts-1 for Epoxidation of Styrene by Molecular Oxygen: Effects of Cataly
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Highly Active/Selective Heterogeneous Catalyst Co/Ts-1 for Epoxidation of Styrene by Molecular Oxygen: Effects of Catalyst Preparation Conditions and Reaction Conditions on the Reaction Jian Jiang Æ Rong Li Æ Huanling Wang Æ Yunfeng Zheng Æ Hangning Chen Æ Jiantai Ma
Received: 2 July 2007 / Accepted: 6 September 2007 / Published online: 25 September 2007 Springer Science+Business Media, LLC 2007
Abstract In the study, highly active/selective heterogeneous catalyst Co/TS-1 has been prepared successfully. The catalyst was characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), diffuse reflectance UV–visible(DR UV–vis) and transmission electron microscopy (TEM). Liquid-phase catalytic epoxidation of styrene to styrene epoxide by molecular oxygen was carried out at atmospheric pressure in the presence of Co/TS-1 catalyst. Sacrificial co-reductant or other promoted reagent such as t-butyl hydroperoxide (TBHP) was not added in the reaction system. A 94.5 mol% conversion of styrene with an epoxide selectivity of 74.3 mol% was attained after 3.5 h reaction. It is noteworthy that there is a synergy between the Co and the Ti in the catalyst in the liquid phase epoxidation of styrene. Keywords Styrene epoxidation Molecular oxygen Co/TS-1 Effect factors
1 Introduction Epoxide compounds are commercially important intermediates [1–4] in the synthesis of the chemicals and pharmaceuticals as they can be easily transformed into a large variety of compounds by means of regioselective ring opening reactions [5]. Epoxide compounds are usually synthesized by epoxidation of alkenes. Therefore, the epoxidation of alkenes is a highly significant chemical reaction. J. Jiang R. Li H. Wang Y. Zheng H. Chen J. Ma (&) College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P.R. China e-mail: [email protected]
Conventionally, the epoxidation of alkenes was usually carried out with organic peracid as an oxidant or by a chlorohydrin process [3, 6]. A lot of waste was formed in either case [7–9]. Now, organic peroxides and especially hydrogen peroxide are used as oxidants for the epoxidation of alkenes under the condition of heterogeneous catalyst. For example, N.S. Patil and coworkers researched the epoxidation of styrene by anhydrous t-butyl hydroperoxide over Au/TiO2 catalyst [10, 11]. D. H. Yin and co-workers found that gold nanoparticles deposited on mesoporous alumina could efficiently catalyze the epoxidation of styrene by anhydrous t-butyl hydroperoxide (TBHP) [12]. Meanwhile, hydrogen peroxide was also widely used as an oxidant for epoxidation of alkenes. Titanium silicalite (TS-1) was reported to catalyze the epoxidation of styrene by anhydrous urea–hydrogen peroxide adduct with good conversion and selectivity [13, 14]. The epoxidation of styrene by aqueous hydrogen peroxide was carried out over TS-1 with high selectivity to styrene oxide ([92%) under the alkali promoted condition [15]. Compared with organic peroxides and hydrogen peroxide, molecular oxygen is
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