Simulation of Surface Chemical Reactions in a Monolith Channel for Hydrogen Production N. Pacheco *,1 , D. Pavone 1 , K. Surla 1 , J.L. Houzelot 2 and E. Schaer 2 1 IFP-Lyon, 2 ENSIC *Corresponding author: IFP-Lyon, BP3, 69360 Solaize, France, nuno-manuel.pacheco-magalhaes@ifp.fr Abstract: This paper intends to show a model of a monolithic reactor for the autothermal reforming process (ATR). This process uses hydrocarbons (fossil fuels or biofuels) to produce H 2 . The ATR chemical reactions take place on the surface of monolith channels coated with a catalyst. The isothermal ATR reactor is modeled using 42 catalytic surface chemical reactions that involve 13 solid species and 7 gas species. To solve the model, two numerical techniques are compared: the Surface Model using weak form equations (SM) and a standard thin Volume Model (VM). This paper shows that the surface modeling (SM) is the better way to calculate the monolith catalytic reactions. Because this simulator is a preliminary version not yet experimentally validated, and in order to verify the simulator result consistency, results are compared with thermodynamic equilibriums calculated by COMSOL. The conclusions are that the results given by the dynamic simulator are in agreement with the thermodynamic equilibriums. Keywords: Autothermal Reforming, Monolith, Methane, Hydrogen, Surface Chemical Reaction, Weak Form, Thermodynamic Equilibrium 1. Introduction IFP has been developing economic and clean processes for hydrogen production for several years. [1] Two main sources are considered: hydrocarbons and biomass. The hydrogen is nowadays considered as a promising energy source for the future. It appears as an interesting way to limit the use of fossil fuels and it could reduce the emissions of greenhouse gases. However, the hydrogen is not a primary source of energy and therefore it must be produced hence, the hydrogen production itself must use low emissions of CO 2 techniques. One efficient way to produce H 2 is via Autothermal Reforming (ATR). This process is mainly based in three chemical reactions: 2 2 4 3H CO O H CH +   →  +  ← (1) I O H CO O CH 2 2 2 4 2 2 + →  + (2) I 2 2 2 H CO O H CO +  →  +  ← (3) I However, this chemical reaction system needs to be catalyzed for the process optimization. To hold the catalyst, IFP decided to use monoliths in the reactor (Figure 1). Figure 1. Monolith examples From a process point of view, the monolith offers advantages like low pressure drop and no fine particle production. In addition, from a research point of view, the monolith channel geometry is well-known and hence can be perfectly described in COMSOL, which is not the case for random loading in packed beds. 2. Objective The aim of this work is to build an ATR monolith reactor simulator using COMSOL. It will take multiphysics into account, mainly mass balances including a surface chemical reaction mechanism involving 42 chemical reactions, 7 gas species and 13 adsorbed species. The monolith considered in this work has deposited over its walls a washcoat impregnated with catalyst sites. This chemically active region will be modeled considering it numerically as a surface (SM) or as a thin volume (VM). The objective is to use the best numerical way to simulate such a thin section of catalyst. In addition, the thermodynamic equilibriums will be calculated in COMSOL to be compared Excerpt from the Proceedings of the COMSOL Conference 2008 Hannover