Durability and regeneration of Ni-Mg-Ca multifunctional catalyst in plasma-assisted and sorption-enhanced H₂ production

The conversion of carbonaceous solid wastes into H₂-rich syngas is an important route for sustainable energy transition. However, maintaining catalyst stability under complex processing conditions remains a major challenge. This study investigates the durability and regeneration behavior of Ni-Mg-Ca multifunctional catalysts during a plasma-assisted and sorption-enhanced reforming system for biomass and plastics co-pyrolysis. The synergistic effects of plasma-catalysis and in-situ CO₂ capture significantly improved performance, achieving a maximum H₂ yield of 71.22 mmol/g (∼69 vol%) while reducing the CO₂ concentration to ∼9 vol%. During cyclic tests, catalyst deactivation was mainly caused by carbon deposition and sintering of active metals. Two different regeneration routes were employed and showed distinct performance and mechanisms. Thermal regeneration (TR) restored approximately 92% of catalytic activity through fully oxidizing coke accumulation and rebuilding the crystalline structure. In contrast, plasma regeneration (PR) recovered over 80% of the initial activity via selective removal of amorphous carbon and the introduction of oxygen vacancies, while largely preserving the catalyst texture. Based on these findings, a hybrid regeneration strategy of frequent non-invasive plasma cleaning and periodic thermal treatment is proposed as an effective way to extend catalyst lifetime and improve the cost effectiveness of waste-to-hydrogen technologies.