Catalytic valorization of lignocellulosic biomass: progress, challenges, and emerging opportunities in metal-based catalysis

The escalating demand for sustainable energy sources and chemical feedstocks has intensified research efforts toward the catalytic conversion of lignocellulosic biomass into value-added products. This comprehensive review critically examines recent advances in metal-based catalytic systems for biomass valorization, encompassing noble metals, transition metals, and their alloys. We systematically analyze the fundamental mechanisms governing catalytic transformations of cellulose, hemicellulose, and lignin, with particular emphasis on structure-activity relationships and catalyst design principles. The review addresses critical challenges including catalyst deactivation, selectivity control, and scalability, while highlighting emerging opportunities in single-atom catalysis, bimetallic synergies, and integrated biorefinery concepts. Furthermore, we discuss the role of advanced characterization techniques and computational approaches in accelerating catalyst discovery. This work provides a roadmap for future research directions aimed at achieving economically viable and environmentally sustainable biomass conversion technologies.