CO ₂ -assisted glycerol reforming for bio-syngas production: catalyst design, reaction kinetics, and process intensification

The rapid growth of biodiesel production has resulted in a significant surplus of glycerol, creating an urgent need for sustainable glycerol valorization technology. Among the various approaches, CO2-assisted glycerol reforming has emerged as a promising pathway for simultaneous glycerol conversion, greenhouse gas utilization, and sustainable syngas production. This review critically discusses major glycerol reforming pathways, including steam reforming, dry reforming, autothermal reforming, aqueous phase reforming, and supercritical water reforming, with particular emphasis on CO2-assisted reforming systems. This review highlights the influence of catalyst physicochemical properties, including metal dispersion, catalyst defect sites, surface basicity, oxygen mobility, and metal–support interactions, on CO2 activation, reforming activity, syngas selectivity, and coke suppression. Thereaction mechanisms, thermodynamic behavior, kinetic models, and rate-controlling steps governing glycerol reforming performance are systematically discussed. Particular attention is given to the synergistic roles of catalyst defect sites, reducible oxide supports, and oxygen mobility in improving carbon utilization efficiency and catalyst stability. Recent advances in process intensification strategies, including chemical looping reformers, membrane reactors, electrified reforming systems, and microchannel reactors are also evaluated for their ability to improve heat and mass transfer, thermal management, and reforming efficiency compared with conventional packed-bed reactors. Finally, the major challenges associated with catalyst durability, energy demand, and industrial scalability are discussed, together with future perspectives on integrated catalyst kinetics and reactor engineering for sustainable glycerol-to-syngas conversion and circular carbon utilization.