(387h) CeO2-Ni-Phyllosilicate Core Shell Catalyst for Stable CH4 Cracking Activity: Regeneration of Deactivated Catalysts with CO2 and Insights on Coke Removal Studies By Drifts

This study reveals the inhibition of coke deposition on a core-shell structured CeO₂-Ni- phyllosilicate (CNP) catalyst during CH₄ cracking in the presence of Ni nanoparticles encapsulated between silica and ceria. At low temperatures (~550 °C), the core-shell catalyst demonstrated excellent H₂ yields with less coke deposition. The deactivated catalyst was treated with CO₂ as a gasifier to regenerate the cracking activity. Due to the high oxygen storage capacity of ceria, which could prevent the coke and speed up the gasification of deposited carbon under methane cracking conditions, the core-shell catalyst exhibited better performance. The increased reducibility and dispersion of Ni in the core-shell catalyst are the reasons for the improved performance of the core-shell catalyst. The TEM, H₂ pulse chemisorption and XRD results emphasized that the core-shell catalyst exhibits high resistance to Ni particle sintering during CH₄ cracking when compared to Ni-PS and Ni-CeO₂ catalysts. The DRIFT spectroscopic analysis of the CNP catalyst revealed an active involvement of CeO₂ derived oxygen species in carbon gasification. Structural changes occurred in the core-shell catalyst due to interaction of Ni with silica and ceria and lack of bulk oxygen resulting in steady activity for over 4 h which was supplemented by the H₂-TPR and in-situ DRIFTS analysis.