Effective hydrogen productions from propane steam reforming over spinel-structured metal-manganese oxide redox couple catalysts

In this study, redox couple metal components (MMn) were introduced in a catalyst design. Main catalytic components (MFe, Co, Ni, or Cu) were combined with Mn, resulting in spinel-structured M2MnO4 for applications to the propane steam reforming reaction as catalysts. Hydrogen selectivity and propane conversions over spinel-structured 30.0 wt% M2MnO4 loaded on 70.0 wt% gamma-Al2O3 support were comparable. The Ni2MnO4/Al2O3 exhibited extremely stable catalytic performance for 3 recycling tests. Catalytic activities decreased in the order Ni2MnO4/Al2O3 > Co2MnO4/Al2O3 > Fe2MnO4/Al2O3 > Cu2MnO4/Al2O3 > Mn2O3/Al2O3. A mechanism for propane steam reforming over M2MnO4 was suggested, and it was found that the catalytic performance for the reforming reaction was closely related to the stability of metal oxidation states via Mn oxide assistance. Furthermore, this study suggested that the Mn oxide delivered oxygen to the main catalytic active site, in particular the Ni component, leading to the rapid cracking and oxidation of C3H8, C2H4, and CH4, and increased hydrogen production.