Hydrogen production through CO2 reforming of CH4 over Pt/CeZrO2/Al2O3 catalysts using a Pd–Ag membrane reactor

CeZrO2/Al2O3 supports with different CeZrO2 loadings were used to obtain stable, high-dispersion Pt (1.5%) catalyts. The solids were evaluated in a conventional fixed-bed reactor and the most stable one was used in a membrane reactor. The fresh and used catalysts were characterized through X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. Pulse experiments were designed to evaluate the oxygen storage capacity of the catalysts. The stable formulation containing 20% CeZrO2 on alumina was shown to be a homogeneous solid solution (Ce0.5Zr0.5O2). The less stable sample, containing 40% of CeZrO2 showed a mixture of phases and its oxygen storage capacity was lower than that of the 20%-loaded formulation. The Pt/20%CeZrO2/Al2O3 catalyst was tested in a membrane reactor built using a self-standing Pd/Ag film with infinite H2 selectivity. When a CH4/CO2 equimolar mixture was fed to the reactor at 823 K, WHSV = 312 h−1, a 75% hydrogen recovery was obtained with a methane conversion 60% above the one that could be obtained in a conventional reactor operating at equilibrium conditions.

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► The stable formulation containing 20% CeZrO2 on alumina was shown to be a homogeneous solid solution (Ce0.5Zr0.5O2).
► The solid solution has a higher oxygen storage capacity than the individual oxides, which inhibited carbon deposition.
► Both Pt/Al2O3 and Pt/40%CeZrO2/Al2O3 deactivated catalysts contained graphitic residues detected through Raman spectroscopy.
► In the membrane reactor the methane conversion was 60% above equilibrium and the H2 recovery was 75%.