Statistical optimization of hydrogen production from bio-methanol steam reforming over Ni-Cu/Al₂O₃ catalysts

Hydrogen has emerged its importance for decarbonization to approach net-zero emissions in 2050. This study aims to develop three highly-porous Ni-Cu/Al₂O₃ catalysts (Ni-to-Cu weight ratio = 10 %, 20 %, and 30 %) for hydrogen production from the steam reforming of “Green” methanol (or bio-methanol). The prepared catalysts require no organic templates, thereby efficiently reducing unnecessary costs. With Taguchi orthogonal array design and analysis of variance (ANOVA), the impacts of selected operating factors on hydrogen productivity under ultrasonic sprays are investigated. The results reveal that the carrier gas flow rate is the most influential factor in H₂ yield at the steam-to-methanol molar ratio (S/C) of 1.5, whereas the temperature is the most impactful factor at S/C = 2.0. The regression between the Taguchi effect value and the ANOVA F value develops a strong linear relationship. The optimal experimental conditions of Ni-Cu(30 %)/Al₂O₃, reaction temperature of 300 °C, N₂ flow rate of 1,000 mL⋅min⁻¹, and S/C = 2.0, achieve 100 % methanol conversion, 39.74 vol% H₂ concentration in the product gas, and 2.93 mol⋅(mol CH₃OH)^-1 H₂ yield. Thes data also show superior performance compared to those in the literature. In long-term stability tests, the prepared catalysts also exhibit high stability and effectiveness commensurate with commercialized Cu-based catalysts.