Valorization of biodiesel waste glycerol to sustainable chemicals

Abstract Biodiesel is an ecofriendly alternative to fossil fuels. Its production generates substantial amounts of crude glycerol, which can pose environmental hazards. Converting glycerol into value‐added chemicals offers a practical strategy to mitigate these risks. Recent advances make it possible to transform crude glycerol directly into high‐value products, including diols (1,3‐propanediol, propylene glycol), polyols, solketal, epichlorohydrin, glycerol carbonate, and biofuels using catalytic (acetalization, dehydration, hydrogenation, oxidation, esterification, and etherification) and biological (fermentation) processes. Heterogeneous catalysts enhance recyclability and process efficiency, and both catalytic and biocatalytic methods have achieved high yields. The integration of microbial and chemical processes in hybrid technologies enables closed‐loop biorefineries that convert waste glycerol into fuels, polymers, cosmetics, and pharmaceuticals. This review highlights recent developments in crude glycerol conversion, emphasizing reaction mechanisms, catalyst design, techno‐economic challenges, and potential industrial applications. These approaches aim to enhance biodiesel sustainability and promote a robust bioeconomy by redefining crude glycerol as a versatile feedstock rather than a waste liability.