Synthesis and regeneration of mesoporous Ni–Cu/Al2O4 catalyst in sub-kilogram-scale for methanol steam reforming reaction

A green template-free method is proposed for the synthesis of mesoporous Ni–Cu/Al₂O₄ catalyst in sub-kilogram scale. In the convenient synthetic method, an intermediate is formed via electrostatic forces and hydrogen bonding interactions between the aluminate ions and the metal ions and/or metal hydroxides under suitable pH conditions. The desired Ni–Cu/Al₂O₄ composites, with Ni/Cu molar ratios of 10%, 20% and 30% of Cu at Cu/Al molar ratio of 10.0%, respectively, are then obtained from calcination. The nitrogen adsorption-desorption isotherms show that the Ni–Cu/Al₂O₄ composites have specific surface areas of 136–170 m²g^-1. The Ni–Cu/Al₂O₄ products are used as catalyst materials in the methanol steam reforming (MSR) of hydrogen and are shown to have a high conversion efficiency (>99%), a low methane concentration, good stability, and a high hydrogen yield (H₂/methanol molar ratio ≈ 3.0) at low reaction temperatures in the range of 200–300 °C. In addition, the coke formation on the catalyst surface is less than 1.0 wt% even after a reaction time of 30 h. Notably, the Ni–Cu/Al₂O₄ catalyst can be regenerated by calcination at 800 °C and retains a high methanol conversion efficiency of close to >99% when reused in MSR.