Dehydrogenation of tetralin on Pd/C and Te-Pd/C catalysts in the liquid-film state under distillation conditions
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Catalysis Letters Vol. 110, Nos. 3–4, September 2006 (Ó 2006) DOI: 10.1007/s10562-006-0108-9
Dehydrogenation of tetralin on Pd/C and Te-Pd/C catalysts in the liquid-film state under distillation conditions Wataru Ninomiya,a Yasuhiko Tanabe,b Yuya Uehara,b Ken-Ichiro Sotowa,b,c and Shigeru Sugiyamab,c,* a Corporate Research Laboratories, Mitsubishi Rayon Co. Ltd., 2-1 Miyuki-cho, Otake, Hiroshima, 739-0693, Japan Department of Chemical Science and Technology, Faculty of Engineering, The University of Tokushima, Minamijosanjima, Tokushima, 770-8506, Japan c Department of Geosphere Environment and Energy, Center for Frontier Research of Engineering, The University of Tokushima, Minamijosanjima, Tokushima, 770-8506, Japan b
Received 31 March 2006; accepted 15 June 2006
The dehydrogenation of tetralin to naphthalene in the liquid-film state on Pd/C and Te-Pd/C catalysts was investigated under reactive distillation conditions at 493 K. The conversion of tetralin was high, when observed using 0.3 g of Pd/C at a specific volume of tetralin (0.9 mL) was used, while the addition of tellurium into the Pd/C catalyst resulted in a similar high conversion using 0.3 g of Te-Pd/C with a somewhat wider volumetric range (0.8–1.1 mL) of tetralin. KEY WORDS: dehydrogenation; tetralin; naphthalene; palladium; tellurium.
1. Introduction The combination of decalin/naphthalene system has been proposed as an effective carrier of hydrogen [1]. The catalytic hydrogenation of naphthalene to decalin was established in the 1940s [2] while active catalysts for the dehydrogenation of decalin to naphthalene have been developed more recently. Saito and co-workers reported that, under reactive distillation conditions, the catalytic dehydrogenation of decalin could be accomplished effectively in the liquid-film state with a Pt/C catalyst [3–5]. In the liquid-film state, the volume of decalin and catalyst are limited, not to suspend the catalyst but to keep wet. For example, the combination of a specific volume of decalin (1.0 mL) and catalyst (0.3 g) was suggested for the liquid-film state while a volume of decalin less or more than 1.0 mL was not suitable for use in the liquid-film state [3–5]. Under these conditions, the temperature of the catalyst layer in the ‘‘liquid-film’’ state exceeds the boiling point of the solution. It has been proposed that such high temperature conditions accelerate the rates of both dehydrogenation and product desorption [5]. Different from conventional gas or liquid phase reactions, the dehydrogenation of decalin (boiling point, 458 and 466 K for the trans- and cis-isomers, respectively) occurs efficiently at 483 K on Pt/C in the ‘‘liquid film state’’ because of the smooth release of hydrogen from the reaction media and the suppression of the reverse reaction [6]. However, such limited conditions are not suitable from a practical
point of view since it is difficult to maintain the specific ratio of the catalyst/substrate in a commercial reaction system. If various volumes of substrate instead of a specific volume of substrate could
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