Performance of Ni-M/Ca12Al14O33 (M= Co, Cu and Fe) bimetallic catalysts in sorption-enhanced steam methane reforming for blue hydrogen production

Abstract

The sorption-enhanced steam methane reforming (SE-SMR) represents a significant advancement in clean hydrogen production. By integrating methane steam reforming with in-situ CO₂ capture, this process offers a sustainable method for hydrogen production while minimizing CO₂ emissions. This study investigates the catalytic performance of monometallic Ni/Ca₁₂Al₁₄O₃₃ and three bimetallic catalysts (Ni-M/Ca₁₂Al₁₄O₃₃, where M=Co, Cu, and Fe) for the SE-SMR reaction. The materials were synthesized using a wet impregnation method and characterized through XRD, XRF, BET, SEM, and TGA to assess their structural, textural, and CO₂ sorption properties. The SE-SMR reaction was conducted in a fixed bed reactor at 700 ℃ with a steam-to-carbon (S/C) ratio of 3, focusing on evaluating catalyst activity, stability, and he synergistic effects of catalytic reforming and CO₂ sorption capacity. The XRD analysis of fresh samples revealed the presence of free CaO, which aids in capturing CO₂ during the reaction. The Ni/Ca₁₂Al₁₄O₃₃ catalyst displayed promising initial activity, which gradually decreased due to sorbent saturation. Among the bimetallic catalysts, Ni-Co/Ca₁₂Al₁₄O₃₃ exhibited the highest average hydrogen purity (78 %) and superior stability due to the synergistic effect of Co and Ni. The Ni-Cu catalyst demonstrated moderate hydrogen purity (∼50 %), whereas the Ni-Fe catalyst showed relatively poor performance, likely due to unfavourable interactions between Ni and Fe, as indicated by XRD. Additionally, the TGA results revealed that Ni-Co/Ca₁₂Al₁₄O₃₃ also maintained excellent cyclic stability for CO₂ adsorption and regeneration over 10 cycles. The kinetic parameters of CO₂ adsorption were estimated using a double exponential method, which indicated the highest specific sorption rate constant for the Ni-Co/Ca₁₂Al₁₄O₃₃ sample.