Selective Oxidation of Cyclohexane by Oxygen in a Solvent-Free System over Lanthanide-Containing AlPO-5
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Selective Oxidation of Cyclohexane by Oxygen in a Solvent-Free System over Lanthanide-Containing AlPO-5 Jun Li • Xu Li • Yong Shi • Dongsen Mao Guanzhong Lu
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Received: 3 February 2010 / Accepted: 14 April 2010 / Published online: 30 April 2010 Springer Science+Business Media, LLC 2010
Abstract Ln-containing AlPO-5 (Ln = La, Ce, Sm, Dy, Y, Gd) were synthesized hydrothermally in the presence of HF, and characterized by XRD, UV-vis, SEM, N2 adsorption/desorption, FT-IR, solid state 27Al MAS NMR and ICP-AES techniques. The results showed that all the samples had good crystallinity and high specific area. Isomorphous substitution of Ln ions for Al?3 occurred. The lanthanide ions were incorporated into the frameworks or were highly dispersed on extra frameworks of the samples. The newly synthesized catalysts all were efficient for the oxidation of cyclohexane in a solvent-free system, especially Gd–AlPO-5. Near 13% conversion of cyclohexane were achieved on the catalyst Gd(60)–AlPO-5 with Al/Gd of 60 under the conditions of 0.5 MPa O2, 413 K and 4 h reaction. The total selectivity to cyclohexanol and cyclohexanone was up to 92%. In addition, the catalyst Gd(60)– AlPO-5 was recyclable for the titled reaction system.
J. Li (&) X. Li Y. Shi D. Mao G. Lu Research Institute of Applied Catalysis, Shanghai Institute of Technology, 200235 Shanghai, People’s Republic of China e-mail: [email protected] X. Li e-mail: [email protected] Y. Shi e-mail: [email protected] D. Mao e-mail: [email protected] G. Lu e-mail: [email protected] G. Lu Research Institute of Industrial Catalysis, East China University of Science and Technology, 200235 Shanghai, People’s Republic of China
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Keywords AlPO-5
Cyclohexane Oxidation Lanthanide
1 Introduction Heterogeneous catalytic oxidations are of growing importance for modern chemical industry, such as selective oxidation of cyclohexane. Cyclohexane can be oxidized to cyclohexanol and cyclohexanone, which are important intermediates in the production of adipic acid and caprolactam. Caprolactam is often used to manufacture nylon-6 and nylon-66 polymers [1–4]. In addition, cyclohexanol and cyclohexanone were also used as the solvent of lacquers and homogenizers for soaps and synthetic detergent emulsions [2]. However, cyclohexane oxidation was considered to be the least efficient in all major industrial chemical processes [5]. Cyclohexane conversion was lower than 5% in order to obtain high selectivity to the goal products. Moreover, in most cases, extreme reaction conditions such as high pressure and high temperature in conjunction with low activity make the process less attractive. So, it’s necessary to find environmentally friendly catalytic system for activation of cyclohexane under mild reaction conditions. Recently, some new catalyst materials and catalytic systems have been developed for the selective oxidation of cyclohexane. Fe(III) and Mn(III) complexes were synthesized and employed as catalysts in the oxidation of cyclohexane under mild conditions, convers
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