Synthesis, characterization and catalytic application of bi- and trimetallic Al-HMS supported catalysts in hydroconversion of n-heptane M.H. Peyrovi a, *, T. Hamoule a , B. Sabour a , M. Rashidzadeh b a Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran 1983963113, Iran b Research Institute of Petroleum Industry (RIPI), Tehran 1485733111, Iran 1. Introduction Hydroconversion of straight-chain paraffins plays a crucial role in the oil refining industry to enhance the octane number of gasoline, to improve the low temperature performance of diesel, and to produce lube oils with a high viscosity index [1,2]. This reaction is carried out using Pt/Al 2 O 3 –Cl catalyst as a bifunctional catalyst [3–5]. It is well known that addition of second metal such as rhenium, iridium or tin can modify the activity, selectivity and stability of platinum catalyst [6–12]. The major reactions promoted by bifunctional catalysts are hydrogenation, dehydro- genation, isomerization, cyclization and hydrocracking [13–15]. The acid function, supplied by the support, catalyses isomerization and cyclization reactions needed for producing high octane compounds such as aromatic hydrocarbons and multibranched isoparaffins [16]. It has been reported that Pt–Re and Pt–Ir have high activity for the hydrogenolysis of hydrocarbons, producing methane and other light hydrocarbons of low value [17]. In the industrial practice this undesirable activity is suppressed by sulfidation. This is a costly operation that must be performed after regeneration of catalyst. For this reason the use of trimetallic catalysts aims primarily at the elimination of sulfidation. Sn is one of the most used elements among other inactive metals. In the past few decades, many studies have been performed on the catalytic performance of metal-loaded zeolite bifunctional catalysts. It was generally considered that microporous zeolite-based catalyst have advantages in producing lower coking and higher hydrocracking activity with respect to the amorphous catalysts [18]. However, their applications were limited in the conversion of large molecules due to the small pore size channel of microporous zeolites [19]. Recently, researchers reported the n-paraffin hydroconversion over monometallic mesoporous catalysts and found remarkable selectivity to aromatics and isomers due to high acidity content of these materials especially in the case of Al containing mesoporous materials [20–28]. In the previous work, for the first time we reported mesoporous Pt/Al-HMS catalysts with different Si/Al ratios showing high catalytic activity for n- heptane reforming with unique selectivity to multibranched isoheptanes and aromatic products [29]. This results encouraged us to investigated the activity and selectivity of bi- and trimetallic mesoporous catalysts in hydroconversion of n-heptane. Therefore, in this work, we have investigated the catalytic activities of Pt–Sn, Pt–Re and Pt–Re–Sn catalysts supported on Al-HMS materials for the hydroconversion of n-heptane. 2. Experimental 2.1. Materials and methods The Al-HMS material was synthesized by sol–gel method similar to that described by Mokaya and Jones [30] using tetraethylorthosilicate (TEOS, Merck) as the silica source, alumi- num isopropoxide (Merck) as the aluminum source and dodecy- lamine (Merck) as the surfactant. The sample was obtained by Journal of Industrial and Engineering Chemistry 18 (2012) 986–992 A R T I C L E I N F O Article history: Received 31 July 2011 Accepted 15 October 2011 Available online 11 January 2012 Keywords: Al-HMS support Bimetallic catalyst Trimetallic catalyst Hydroconversion n-Heptane A B S T R A C T Bi (Pt–Sn and Pt–Re) and trimetallic (Pt–Sn–Re) catalysts supported on Al-HMS material (Si/Al = 10) were prepared and characterized by X-ray diffraction, N 2 adsorption–desorption and temperature programmed reduction techniques. TPR results showed the interaction between metal species and mesoporous framework that can affect the acidity of mesoporous materials. Catalytic performance of samples was investigated for hydroconversion of n-heptane. A comparison of Pt–Re and Pt–Sn catalysts supported on Al-HMS-10 and Al 2 O 3 –Cl under the same conditions is made. Mesoporous catalysts exhibited better activity in comparison with Al 2 O 3 –Cl supported catalysts. Performance of trimetallic catalysts is better than bimetallic catalysts. ß 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +98 21 29902892; fax: +98 21 22431663. E-mail address: m-peyrovi@cc.sbu.ac.ir (M.H. Peyrovi). Contents lists available at SciVerse ScienceDirect Journal of Industrial and Engineering Chemistry jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jiec 1226-086X/$ – see front matter ß 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.jiec.2011.10.003