Solventless hydrogenation of benzene to cyclohexane over a heterogeneous Ru–Pt bimetallic catalyst Hongli Liu, Ruiqi Fang, Zhong Li, Yingwei Li n School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China HIGHLIGHTS  Ru–Pt/MIL-101 was prepared by a colloidal deposition method.  Ru and Pt showed a positive synergistic effect on the hydrogenation.  The catalyst exhibited excelling activities in neat benzene hydrogenation.  The reaction showed a first-order dependence on H 2 pressure. article info Article history: Received 20 June 2014 Received in revised form 22 September 2014 Accepted 25 September 2014 Available online 7 October 2014 Keywords: Catalysis Kinetics Metal–organic frameworks Nanoparticle Hydrogenation abstract The hydrogenation of benzene to cyclohexane has attracted renewed attention in the chemical and petroleum industry, due to its application in the synthesis of many useful chemical intermediates. However, the development of highly efficient hydrogenation processes under mild solvent-free conditions is still a great challenge. Herein, we report a highly efficient Ru–Pt bimetallic catalyst, which was deposited on a zeolite-type MOF (MIL-101) by a simple colloidal deposition method, for neat benzene hydrogenation to cyclohexane. The catalyst system was shown to be able to provide excellent activities with a high selectivity for cyclohexane (in up to 499% yield). The enhanced reactivity is rationalized in terms of the synergy of Ru and Pt. The kinetics of neat benzene hydrogenation by the Ru–Pt/MIL-101 catalyst was investigated. The reaction showed a zero-order dependence on benzene while a first-order dependence on H 2 pressure. A kinetic model of hydrogenation of neat benzene over the Ru–Pt catalyst was established based on the experimental results. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction The hydrogenation of benzene to cyclohexane is of crucial importance in both laboratory and industrial synthetic chemistry (Weissermel and Arpe, 2003). For instance, millions of tons of benzene are hydrogenated annually to give cyclohexane, which is known as one of the key industrial intermediates in the manu- facturing of Nylon-6 and Nylon-66. At present, most of the worldwide production capacity of cyclohexane is obtained from the process of benzene hydrogenation (Vangelis et al., 2010). However, owning to the resonance stabilization resulting from the strong π-conjugation in the aromatic ring (Graham and Frhyle, 2011), the hydrogenation generally performs at temperatures 4373 K and initial H 2 pressures over 30 bar, and/or in dilute solvent systems, leading to unavoidable problems of undesired by-product and time- and resource-consuming steps to separate products (Cimpeanu et al., 2009; Duan et al., 2013; Indra et al., 2013; Chen et al., 2005; Hubert et al., 2011). To date, the complete hydrogenation of benzene to cyclohexane under mild solvent-free conditions with acceptable rates still remains a challenge (Tonbul et al., 2014; Zahmakıran et al., 2010a, 2010b, 2012; Pan and Wai, 2009; Mévellec et al., 2004; Bayram et al., 2010; Zahmakiran and Özkar, 2008). In view of these premises, aiming at promoting the sustainable development of the chemical industry, it is desirable to develop highly active and selective catalysts for the hydrogenation of benzene under mild solventless conditions. Recently, a large number of research has demonstrated that the properties of bimetallic catalysts are significantly different from their corresponding monometallic constituents in many catalytic systems because of the positive synergistic effects between the two metals (Sankar et al., 2012; Yu et al., 2012; Balu et al., 2010). Meanwhile, bimetallic catalysts have also been reported for a range of hydro- genation reactions including benzene hydrogenation (e.g., Pd–Rh/ CNT, Pt–Co/γ-Al 2 O 3 , Ru–Ni/C), exhibiting enhanced catalytic perfor- mance in both activity and selectivity (Duan et al., 2013; L. Zhu et al., 2013; Q.L. Zhu et al., 2013; Yoon et al., 2009; Lu et al., 2008; Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ces Chemical Engineering Science http://dx.doi.org/10.1016/j.ces.2014.09.050 0009-2509/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author. E-mail address: liyw@scut.edu.cn (Y. Li). Chemical Engineering Science 122 (2015) 350–359