Integration of catalytic methane oxy-reforming and water gas shift membrane reactor for intensified pure hydrogen production and methanation suppression over Ce0.5Zr0.5O2 based catalysts

The production of pure hydrogen from methane or biomethane is a multistep process that can be intensified by the use of membrane reactors. In this study we have synthetized by microemulsion technique Rh and Pt supported over Ce0.5Zr0.5O2 to be applied to the catalytic methane oxy-reforming and water gas shift (WGS) reaction respectively. At first the reformate produced by the reforming process at 750 ◦C was purified using and hydrogen selective empty Pd-based membrane operated at 400 ◦C. This led to pure hydrogen production but it resulted also in a not-fully exploitation of the membrane performances. Thus, the Pt-based catalyst was loaded in the membrane reactor configuration leading to in situ hydrogen production that helped to increase the separation driving force. The water gas shift reaction downstream oxy-reforming was also studied on the Pt/Ce0.5Zr0.5O2 catalyst and evidenced the consumption of hydrogen by methanation at high H2/H2O ratio. Comparing the WGS membrane reactor with a classical fixed bed demonstrated that removing hydrogen led to increased CO conversion over the equilibrium of an analogous fixed bed, higher H2 yield and suppression of the methanation reaction, even at high inlet H2/H2O ratio. Optimizing the reaction conditions allowed to reach high hydrogen recoveries (89 %) for the integrated oxy-reforming/membrane water gas shift at high GHSV and without the need of a sweep gas.