Perspectives on the Catalytic Processes for the Deep Valorization of Carbohydrates into Fuels and Chemicals

The global depletion of fossil resources, combined with accelerating climate change and environmental concerns, is driving intensive research into alternative, sustainable sources of energy and raw materials. Particular attention is being paid to lignocellulosic biomass as the most abundant and renewable organic resource. The catalytic conversion of biomass-derived carbohydrates into high-value-added products (fuels and chemicals) aligns with the principles of sustainable development and offers a viable alternative to petroleum-based feedstocks. This review provides a product-oriented perspective on the deep valorization of carbohydrates, focusing on catalytic strategies that enable the production of renewable fuels and chemicals. It highlights two key stages in the valorization of lignocellulosic biomass: (1) the acid-catalyzed conversion of carbohydrates into platform molecules (furfural, 5-hydroxymethylfurfural, and levulinic acid); and (2) the selective hydrogenation and hydrogenolysis of these intermediates to obtain target end products. These target products fall into two major categories: (i) biofuels and fuel additives; and (ii) green chemicals, such as solvents, pharmaceuticals, agrochemicals, cosmetics, and intermediates for the synthesis of biobased polymeric materials, including polyesters, resins, and polyurethanes. Particular emphasis is placed on recent advances in the development of heterogeneous catalysts. Solid acid catalysts used in the synthesis of platform molecules are discussed, along with ruthenium-based catalysts employed in the subsequent hydrogenation and hydrogenolysis steps. Recent efforts toward integrating both catalytic stages into a single one-pot processes using bifunctional metal-acid catalysts and dual catalytic systems based on ruthenium are also reviewed, as they represent a promising route to simplify biomass valorization schemes and improve product selectivity toward fuels and chemicals.