CFD Online Discussion Forums - porous medium and reactions

Dear users: I am simulating "Flow and Heat Transfer in a fixed bed reactor Catalytic. Enters the catalytic reactor a gas stream. I intend to model chemical species transport and chemical reaction (Endothermic, exothermic and reversible), which are as follows: CH4 + H2O<--->CO + 3H2 CO + H2O<---->CO2 + H2 The idea is to use the model of porous medium for the area was packed and behave as a catalyst for such reactions. My questions are as follows: - What considerations should I specify to ensure that the porous medium acting as a catalyst for the reactions involved in the problem? - What model must be activated so that the reactions occurring in the porous medium: volumetric reaction, reaction on the surface of the wall? -Is it necessary to define areas or sites where chemical reactions occur involved in the problem? - The system "porous medium and reactions" Is it as a homogeneous system or should be defined two phases (phase gas and solid phase) and to note that the program holds the porous medium as fluid? In addition it is intended to model the heat transfer in the porous medium and want to specify what constitutes material, it will act at once as a catalyst for the reactions that I gave earlier. How Fluent manages this data? If the program finds the porous medium as fluid and as porous assure you that this area does not move. What is the best representation of packed bed reactor? I hope can help me. Thank you!