Marked Effect of Mo and Fe Addition Upon Liquid Phase Methanol Reforming with Water Over Al 2 O 3 Supported Pt Catalysts
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Marked Effect of Mo and Fe Addition Upon Liquid Phase Methanol Reforming with Water Over Al2O3 Supported Pt Catalysts Takehiko Sakamoto Æ Hiroyuki Morishima Æ Akihiro Yoshida Æ Shuichi Naito
Received: 15 June 2009 / Accepted: 9 July 2009 / Published online: 21 July 2009 Ó Springer Science+Business Media, LLC 2009
Abstract Successively impregnated Pt–Mo/Al2O3 and Pt–Fe/Al2O3 catalysts exhibited large enhancement effect in H2 formation rate of liquid phase methanol reforming. Added Mo oxide forms monolayer on Al2O3 and facilitates the higher dispersion of Pt particles. In the case of Fe, formation of some surface bimetallic clusters between Pt and Fe was confirmed by XAS analysis, which causes the enhancement effect of H2 formation in MeOH–H2O reaction. Keywords Liquid phase methanol reforming Pt–Mo/Al2O3 Pt–Fe/Al2O3 Bimetallic cluster
1 Introduction The shortage of fossil fuels and the associated pollution problems during their combustion has attracted great attention towards the search of alternative fuels [1]. Hydrogen gas is the most excellent alternative candidate, since it is an inherently clean fuel to form only water and is highly reactive so that excellent thermal efficiencies can be obtained [2]. Concerning to the purpose for the reduction of significant emissions, fuel cells are superior in terms of potentially high energy conversion efficiencies, and for these, hydrogen is much more reactive than any other fuels [3]. However, the generation of hydrogen gas consumes a large amount of energy, either from natural gas or via the electrolysis of water [4].
T. Sakamoto H. Morishima A. Yoshida S. Naito (&) Department of Material and Life Chemistry, Kanagawa University, 3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama, 221-8686, Japan e-mail: [email protected]
Liquid phase reforming of methanol with water is one of the most promising processes for hydrogen production. As compared with the usual steam reforming reaction, the advantages of liquid phase reforming are the possibility to make more compact and simple reaction equipment and needless of the evaporation energy of methanol aqueous solution. In spite of its importance, there are few researchers that dealt with the liquid phase reaction from the point of heterogeneous catalysis except for an anode reaction in direct methanol fuel cell (DMFC) [5, 6]. Dumesic et al. [7, 8] reported the liquid phase reaction of methanol and other oxygenates with water over supported Pt catalysts at 500 K. The activity of hydrogen production was highly dependent on the employed supported materials and Pt/TiO2 catalysts is the most active among CeO2, ZnO and SiO2 supported Pt catalysts. Okamoto et al. [9] reported the liquid phase reforming of methanol to form hydrogen over Cu/ZnO catalysts at 500 K with the high selectivity (more than 99%) for CO2. However, these studies are performed relatively high pressures (around 10 MPa) and temperatures (above 500 K). The most significant issue to be solved for the development of useful high efficiency methanol fuel cells
