Resource utilization of waste CeO₂-based deNO_x composite catalysts for hydrogen production via steam reforming

Resource utilization of waste deNO_x catalysts has become a major demand. A new resource utilization way of waste Ce–W-O_x/TiO₂ (TCW) deNO_x catalysts for steam reforming reaction using different hydrogen resources was verified. The waste TCW carrier supported NiO (N/TCW) exhibited excellent catalytic performance and formaldehyde was verified as the optimum hydrogen resource. The optimum N/TCW showed 104.5% H₂ selectivity at 500 °C and high H₂ production rate (13.1 L min⁻¹). Its formaldehyde conversion was higher than 96.0% at the range of 450–600 °C. Analysis showed that the richness of hydroxyl group determined the reaction rate and selectivity. The enhancement of surface acid quantity and redox properties could improve the catalytic selectivity and activity. The in situ DRIFT study verified that water molecules must participate in the two types of reaction processes for the steam reforming reaction and the hydrogen bond accelerate the reaction by reducing reaction steps. The adsorbed formaldehyde species firstly converted to di-oxymethylene, then transformed to formate, species. Finally, the H₂ and CO₂ generated by the dehydrogenation of intermediate. The solution can solve two problems at the same time: solid pollution of waste Ce–W-O_x/TiO₂ catalyst and energy shortage.