Ethanol CO₂ reforming on La₂O₃ and CeO₂-promoted Cu/Al₂O₃ catalysts for enhanced hydrogen production

[Graphic abstract]

3%Ce- and 3%La-promoted 10%Cu/Al₂O₃ catalysts were synthesized via a sequential incipient wetness impregnation approach and implemented for ethanol CO₂ reforming (ECR) at 948–1023 K and stoichiometric feed ratio. CeO₂ and La₂O₃ promoters reduced CuO crystallite size from 32.4 to 27.4 nm due to diluting impact and enhanced the degree of reduction of CuO → Cu⁰. Irrespective of reaction temperature, 3%La–10%Cu/Al₂O₃ exhibited the highest reactant conversions, H₂ and CO yields followed by 3%Ce–10%Cu/Al₂O₃ and 10%Cu/Al₂O₃. The greatest C₂H₅OH and CO₂ conversions of 87.6% and 55.1%, respectively were observed on 3%La–10%Cu/Al₂O₃ at 1023 K whereas for all catalysts, H₂/CO ratios varying from 1.46 to 1.91 were preferred as feedstocks for Fischer-Tropsch synthesis. Activation energy for C₂H₅OH consumption was also reduced with promoter addition from 53.29 to 47.05 kJ mol⁻¹. The thorough CuO → Cu⁰ reduction by H₂ activation was evident and the Cu⁰ active phase was resistant to re-oxidation during ECR for all samples. Promoters addition reduced considerably the total carbon deposition from 40.04% to 27.55% and greatly suppressed non-active graphite formation from 26.94% to 4.20% because of their basic character and cycling redox enhancement.