Integration of methanol steam reforming and combustion in a microchannel reactor for H 2 production: A CFD simulation study G. Arzamendi a , P.M. Die ´ guez a , M. Montes b , M.A. Centeno c , J.A. Odriozola c , L.M. Gandı ´a a, * a Departamento de Quı´mica Aplicada, Edificio de los Acebos, Universidad Pu ´blica de Navarra, Campus de Arrosadı´a s/n, E-31006 Pamplona, Spain b Departamento de Quı´mica Aplicada, Facultad de Ciencias Quı´micas de San Sebastia ´n, Universidad del Paı´s Vasco, P8 Manuel de Lardiza ´bal 3, E-20018 San Sebastia ´n, Spain c Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-Universidad de Sevilla, Avda. Ame ´rico Vespucio 49, 41092 Sevilla, Spain 1. Introduction There is an increasing interest in methanol as a fuel for power units based on low-temperature small size fuel cells, mainly of the proton-exchange-membrane (PEMFC) type. Main applications of these systems are the replacement of batteries in portable electronics as well as auxiliary power units [1]. Another important application of fuel cells will be in the transportation sector; in this regard, methanol can be used also as a fuel for onboard production of the hydrogen to be fed to the fuel cells of the vehicles driven by electric engines [2]. The advantages of using methanol for hydrogen production can be summarized as follows [1,3]: (i) high hydrogen to carbon ratio (4, like methane); (ii) it is liquid at ambient conditions thus overcoming the problems of hydrogen distribution and storage; (iii) is miscible with water so both methanol and water can be premixed in fuel cartridges; (iv) is biodegradable and free of sulfur; (v) the absence of C–C bonds and its reactivity allows conversion to hydrogen (reforming) at lower temperatures (200–350 8C) than for most other hydrocarbon fuels (above 500–600 8C); (vi) low temperature reforming with selective catalysts leads to low levels of CO formation so secondary conversion such as the water gas shift (WGS) reaction is generally unnecessary in the case of methanol; (vii) its net energy content is comparable to that of gasoline on a well-to-wheel basis; (viii) the theoretical energy input required (145 J/kg of usable H 2 ) for the steam reforming of methanol (SRM) is about the same that for other fuels. Of course, there are also some drawbacks: methanol is toxic, being ingestion the main concern, and the H 2 yield is relatively low (18.9 g H 2 per 100 g of steam-reformed methanol) compared with other fuels (50.3 g H 2 per 100 g of steam- reformed CH 4 ). As concerns the use of fuel cells for portable applications, one of the most important challenges is the availability of a compact and light unit of H 2 supply. Catalytic microreactors can contribute to solve this technological problem [1,4–6]. Microreactors are very compact, have a high surface to volume ratio, exhibit enhanced heat and mass transfer rates, produce extremely low pressure drop and allow easy thermal integration of the processes involved. Within this context, the aim of this computational fluid dynamics (CFD) simulation study is to guide the design of an unit based on catalytic microchannel reactors for the production of hydrogen from methanol. This work forms part of a joint project with the final goal of constructing the fuel microprocessor including both the primary conversion of methanol and the CO mitigation stages and put it into operation. This paper is only concerned with the initial conversion unit and the idea is simple: to couple in the same device the endothermic (DH  250  C ¼ 59:5 kJ=mol) steam reforming of metha- nol (SRM) with the exothermic combustion of methanol (DH  250  C ¼673:2 kJ=mol) in air for heating purposes. The SRM reaction has been extensively studied; it is catalyzed by a variety of compounds mainly based on copper or palladium and the state of the art on this subject has been updated and can be consulted in excellent reviews [1,2,7]. Catalysis Today 143 (2009) 25–31 ARTICLE INFO Article history: Available online 18 November 2008 Keywords: Hydrogen for PEMFC Microchannel reactor Methanol steam reforming Methanol combustion Computational fluid dynamics (CFD) ABSTRACT A computational fluid dynamics (CFD) study of the thermal integration of the steam reforming of methanol (SRM) and the combustion of methanol in a catalytic microchannel reactor is presented. This issue is of interest for in situ H 2 production for portable power units based on low-temperature PEM fuel cells. Three-dimensional simulations have been carried out under relevant conditions for the SRM reaction that have shown that microreactors allow achieving complete methanol reforming and combustion at space velocities as high as 50,000 h 1 , with selectivities for H 2 above 99% at relatively low temperatures in the 270–290 8C range. ß 2008 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +34 948 169605; fax: +34 948 169606. E-mail address: lgandia@unavarra.es (L.M. Gandı ´a). Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod 0920-5861/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.cattod.2008.09.034