Synthesis and investigation of anchored copper (II) complexes within MCM-41 as selective catalysts for epoxidation of ol
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Synthesis and investigation of anchored copper (II) complexes within MCM-41 as selective catalysts for epoxidation of olefins Somayyeh Kalami • Hamid Reza Aghabozorg Behdad Ghaderi Ashtiani
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Published online: 8 December 2012 Ó Springer Science+Business Media New York 2012
Abstract In the present study, preparation, characterization and catalytic activity of encapsulated copper (II) complexes within MCM-41 were investigated. The mesoporous molecular sieve MCM-41 was synthesized and grafted with 3-(trimethoxysilyl)-1-propanethiol to give a thiol modified material (MCM-41-S). The prepared material successively was reacted with acrylic acid and acrylonitrile to give AA-MCM-41 and AN-MCM-41, respectively. Using hexamethyldisilazane and copper (II) chloride, copper (II) complexes in the cavities of MCM-41 (Cu-AA-MCM-41 and Cu-AN-MCM-41) were prepared. The presence of copper (II) complex on the surfaces of host matrix and the structure of prepared catalyst is investigated by FT-IR, inductively coupled plasma-optical emission spectroscopy (ICP-OES), powder X-ray diffraction (XRD) and BET nitrogen adsorption–desorption methods. The catalytic activities of the catalysts were studied in epoxidation of olefins. The results showed that activities of the prepared catalysts (Cu-AA-MCM-41 and Cu-AN-MCM41) and their selectivity to corresponding epoxides were more than those of MCM-41. In addition, the synthesized heterogeneous catalysts were truly reusable.
Dedicated to the memory of Professor Hossein Aghabozorg. S. Kalami Faculty of Chemistry, Tarbiat Moallem University, Tehran, Iran H. R. Aghabozorg (&) Catalysis Research Center, Research Institute of Petroleum Industry (RIPI), Tehran, Iran e-mail: [email protected] B. G. Ashtiani Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Keywords MCM-41 Acrylic acid Acrylonitrile Epoxidation Copper (II) complex
1 Introduction Mesoporous materials especially MCM-41, with high surface area, large pore volume, optimal pore size, precisely ordered pore structure and high chemical and thermal stability are highly attractive for applications in heterogeneous catalysts [1–3]. Moreover, the abundant silanol groups (Si–OH) on their surfaces make them easily organically functionalized and metal complexes grafted them to catalytic active species [4–6]. Among the variety of catalytically active metal complexes, copper-containing molecular sieves are important catalysts in many liquid-phase oxidation reactions such as epoxidation of alkenes [7] and partial oxidation of alkyl aromatics [8]. The demand for the use of environmentally friendly copper-containing catalyst in the liquid-phase oxidation catalysis provides a powerful means for the development of recyclable catalysts. A number of works have dealt with the immobilization of copper complexes onto different supports such as, silicates, zeolites and other molecular sieves [9]. A major drawback encountered in this regard is the instability of the metal ion in the structure of cat
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