Development of multifunctional Ni/CaO-Al₂O₃ pellet for hydrogen production from sorption-enhanced steam reforming of simulated biogas

Multifunctional material, Ni/CaO-Al₂O₃ was successfully developed in pellet form for practical application for hydrogen production via sorption-enhanced steam reforming of biogas. The pellet possesses mechanical robustness but led to diffusion limitation, lowering H₂ purity to 80% at 650 °C and 1 bar. To improve performance, CeO₂ and MgO promoters were introduced. The Ce-modified pellets (Ni-Ce/CaO-Al₂O₃) showed superior properties due to higher surface area, improved Ni dispersion, and oxygen vacancies. They maintained stable H₂ purity (77% v/v) under CO₂-rich conditions (CH₄/CO₂ = 60/40% v/v) and achieved high purity at an optimal S/C ratio of 2, reducing energy demand by ∼28% compared with S/C = 3. Long-term stability over 20 cycles confirmed a minor drop in H₂ purity, decreasing from 77% to 72% with no significant changes in CO, CH₄, or CO₂, indicating strong resistance to deactivation.