One-pot catalytic conversion of cellulose biomass to bioethanol at low pressure and temperature conditions: H₂O as a self-hydrolytic agent

The development of sustainable protocols for the synthesis of bioethanol from cellulose biomass using reduction-free heterogenous catalysts without external H₂ is a challenging task. In this work, a highly active and robust Ni-Pd/iron oxide catalyst has been reported for the synthesis of bioethanol from microcrystalline cellulose (MCC) in a single-step, one-pot process using H₂O as a green solvent. The catalysts were synthesized by facile and scalable co-precipitation and wet-impregnation methods. H₂O functions as a hydrolytic agent, and Ni-Pd composites play the role of the hydrogenolysis/hydrogenation active sites. The different catalytic profiles were obtained over wet-impregnated and co-precipitated catalysts by altering the temperatures and pressure conditions, respectively. The wet-impregnated Pd-Ni/iron oxide catalyst provided improved catalytic activity due to uniformly distributed active metal particles observed from FE-SEM analysis, optimum crystalline size, particle size, and high surface area. In addition, the spent catalyst was tested and proven to be reusable with comparable bioethanol yields and greater cellulose conversion under optimized experimental conditions. In brief, the finding further expands the possible valorization of any cellulosic-based biomass into a high-value bioethanol chemical and fuel.