Regenerable oxygen-deficient Ni/y-Al2O3 catalyst for efficient glycerol aqueous phase reforming

Authors: PARK, JUNG HYUN - University Of Illinois Urbana-Champaign; LU, HONG - University Of Illinois Urbana-Champaign; Sharma, Brajendra; Johnston, David; RAJAGOPALAN, NANDAKISHORE - University Of Illinois Urbana-Champaign; KIM, JAEMIN - University Of Illinois Urbana-Champaign

Submitted to: Journal of Materials Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2025
Publication Date: 12/5/2025
Citation: Park, J., Lu, H., Sharma, B.K., Johnston, D., Rajagopalan, N., Kim, J. 2025. Regenerable oxygen-deficient Ni/y-Al2O3 catalyst for efficient glycerol aqueous phase reforming. Journal of Materials Chemistry. https://doi.org/10.1039/D5TA08347H.
DOI: https://doi.org/10.1039/D5TA08347H

Interpretive Summary: Producing fuel gases such as hydrogen and methane from sustainable feedstock is key to developing cleaner energy routes. Glycerol, a renewable byproduct from biodiesel manufacturing and bioethanol production, is an attractive feedstock for converting to fuel gases, like hydrogen and methane, due to its oversupply relative to demand. The fuel gas yield is strongly influenced by the catalyst used in this process. For practical applications, catalysts must exhibit excellent hydrothermal stability to sustain fuel gas production over time. The desired catalyst possesses uniform dispersion of active metals, small particle size, strong metal-support interactions, and highly exposed boundaries among catalyst, support, and reactants. This study describes the careful selection of catalyst materials with tailored synthesis methods to develop durable, regenerable, practical catalysts with enhanced activity for sustainable fuel gas production. The outcome from this work can be applied to convert a variety of waste biomass/biorefinery byproducts for the sustainable production of gaseous fuel, which will help improve the economics of biorefineries and thereby help farmers by increasing the value of waste biomass generated on the farms, and also the utilization of organic waste present in various streams, like bioethanol production.

Technical Abstract: Aqueous phase reforming (APR) of glycerol represents a promising pathway for sustainable fuel gas production. Nickel-immobilized gamma alumina (Ni/y-Al2O3) has been recognized as an effective and alternative to noble metal catalysts, but the phase transformation from y-Al2O3 to AlOOH under hydrothermal conditions negatively affects its long-term catalytic performance. To address this challenge, we synthesized a Ni/y-Al2O3 catalyst via a Ni-exsolution technique from NiAl2O4 spinel oxide. The catalyst achieved a gasification yield of 49.2% with a higher heating value (HHV) of 9.2 MJ/kg of glycerol in 45 min at 250 C, producing hydrogen, carbon monoxide, and methane, which is comparable to that of Ru-catalyst. The spent catalyst was regenerated, resulting in an increased gasification yield of 52.6% and HHV of 10.3 MJ/kg of glycerol, with enhanced H2 (106.7%) and CH4 (123.0%) production compared to the fresh catalyst. This remarkable performance is primarily attributed to improved crystallinity of the y-Al2O3 and strengthened Ni and y-Al2O3 interactions induced by increased oxygen vacancies and electron density. This study highlights the significance of the metal exsolution approach in catalyst preparation, demonstrating that chemical structure modulation through regeneration is crucial for enhancing both the catalytic activity and durability of y-Al2O3 supported catalysts in glycerol APR.