Exploring catalytic pathways for glycerol valorization into 1,3-propanediol: A review on hydrogenolysis

Glycerol, as the main by-product in the biodiesel production industry, has attracted attention of numerous researchers as a platform chemical to make wide variety of value added products that has domestic and commercial applications worldwide. The growing surplus of crude glycerol has intensified interest in its valorization into high-value-added chemicals. However, the complex composition of crude glycerol poses substantial challenges in purification, which needs to be addressed to enable its efficient downstream applications. This review critically explores the production and purification of crude glycerol, followed by a comprehensive overview of its transformation into value-added derivatives. Particular emphasis is placed on the catalytic hydrogenolysis of glycerol to 1,3-propanediol (1,3-PD), a promising bio-based chemical with broad industrial and commercial applications. Recent advancements in catalytic designs, particularly the systems based on Pt, Ir, and cost-effective transition metals, are critically examined, with a focus on mechanistic pathways, bifunctional catalytic behavior, operating conditions, stability, and reusability. The review further addresses key techno-economic considerations, environmental sustainability metrics, and the prevailing industrial and commercial landscape, highliting the absence of commercial-scale 1,3-PD production through catalytic glycerol transformation despite promising laboratory-scale achievements. Finally, the downstream purification of 1,3-PD is identified as a critical bottleneck due to its technical and scale-up challenges and costly separation process. The review concludes by outlining the major technological gaps, regulatory challenges, and policy interventions necessary to realize the industrial potential of glycerol hydrogenolysis, positioning it as a viable pathway in the transition toward circular and sustainable biorefinery frameworks.