Ordered mesoporous Fe-Al2O3 based-catalysts synthesized via a direct "one-pot" method for the dry reforming of a model biogas mixture

Biogas plays a vital role in the emerging renewable energy sector and its efficient utilization is attracting significant attention as an alternative energy carrier to non-renewable fossil fuel resources. Since biogas consists mainly of CH₄ and CO₂, dry reforming of methane arises as an appropriate process enabling its chemical conversion to high-quality synthesis gas (syngas: H₂ and CO mixtures). In this study, we synthesized via a direct "one-pot" method following an evaporation-induced self-assembly approach, ordered mesoporous Fe_10%, Ni_5% and Fe_x%Ni_(1-x) (x: 2.5, 5 or 7.5%) in Al₂O₃ as catalysts for syngas production via dry reforming of a model biogas mixture (CH₄/CO₂ = 1.8, at a temperature of 700 °C). Monometallic Fe_10%Al₂O₃ catalyst presented lower reactivity levels and slightly deactivated during catalysis compared to stable Ni_5%Al₂O₃. According to physico-chemical characterization techniques, the incomplete reduction of Fe₂O₃ into Fe₃O₄ rather than Fe⁰ nanoparticles (catalytically active) coupled with the segregation of Fe₃O₄ oxides were the main factors leading to the low performance of mesoporous Fe_10%Al₂O₃. These drawbacks were overcome upon the partial substitution of Fe by Ni (another transition metal) forming specifically bimetallic Fe_5%Ni_5%Al₂O₃ displaying reactivity levels close to thermodynamic expected ones. The formation of Fe-Ni alloys stabilized iron inside alumina matrix and protected it from segregation. Along with the confinement effect, spent catalyst characterizations showed high resistance towards coke deposition.