Co nanoparticles embedded Co-phyllosilicate/ZSM-5 catalyst for boosting hydrogen production from ethanol steam reforming

Abstract

A catalyst supported on kaolin-derived ZSM-5 was designed to immobilize cobalt species for ethanol steam reforming (ESR), demonstrating enhanced activity and stability compared to its counterpart on commercial ZSM-5. The introduction of a Co-phyllosilicate phase grafted onto the ZSM-5 surface resulted in enhanced metal-support interaction within the Co-PS/ZSM-5 catalyst, which provided the active sites with high accessibility and sintering resistance. In contrast to the significant aggregation of Co⁰ nanoparticles observed in the Co/ZSM-5 and Co/CZSM-5 catalysts, the homogeneous Co active sites formed via exsolution from the Co-phyllosilicate precursor effectively suppressed metal sintering and coke deposition. Physicochemical characterization of the catalysts revealed that the Si-O-Co bonds in the residual Co-phyllosilicate played a key role in stabilizing the dispersed Co active sites and suppressing the competing reaction pathway of ethanol dehydration versus dehydrogenation. Consequently, the catalyst avoided the marked decline in H₂ yield associated with the formation and encapsulation of carbon nanotubes on Co sites. Among all tested catalysts, Co-PS/ZSM-5 demonstrated optimal performance, achieving near-complete conversion (∼100%), a high H₂ yield (∼76%), and stable operation over 50 h at 600 °C. This work presents a strategy for utilizing kaolin-derived ZSM-5 as a support for Co-based catalysts, demonstrating their potential for long-term, commercially viable ESR operation.