Polymer electrolyte membrane fuel c

Polymer electrolyte membrane fuel cells (PEMFCs) for household applications utilizeH2 produced from natural gas via steam reforming followed by a water gas shift (WGS) unit.The H2-rich gas contains CO2 and small amounts of CO, which is a poison for PEMFCs. Today, CO ismostly converted by addition of O2 and preferential oxidation, but H2 is then also partly oxidized.An alternative is selective CO methanation, studied in this work. CO2 methanation is then a highlyunwanted reaction, consuming additional H2. The kinetics of CO methanation in CO2/H2 rich gaseswere studied with a home-made Ru catalyst in a fixed bed reactor at 1 bar and 160–240 ◦C. Both COand CO2 methanation can be well described by a Langmuir Hinshelwood approach. The rate ofCO2 methanation is slow compared to CO. CO2 is directly converted to methane, i.e., the indirectroute via reverse water gas shift (WGS) and subsequent CO methanation could be excluded bythe experimental data and in combination with kinetic considerations. Pore diffusion may affectthe CO conversion (>200 ◦C). The kinetic equations were applied to model an adiabatic fixed bedmethanation reactor of a fuel cell appliance.