Insights on production mechanism and industrial applications of renewable propylene glycol

Propylene glycol is a ubiquitous sustainable chemical that have several industrial applications. It can be used as a non-toxic antifreeze, moisturizers, and in cosmetics products. Commercial production of propylene glycol uses petroleum-based propylene oxide. Therefore, there is a need to develop alternative and renewable propylene glycol production routes. Renewable propylene glycol can be produced from catalytic hydrogenolysis of glycerol. This study reviews different catalyst for glycerol hydrogenolysis, the reaction mechanism, and process challenges. Additionally, previous studies related to the economic and environmental assessment of propylene glycol production are presented in detail. The technology readiness level of different production pathways were outlined as well as the challenges and future direction of propylene glycol production from glycerol and other renewable feedstocks. Catalytic transfer hydrogenolysis, a process that uses renewable H-donors in liquid medium for hydrogenolysis reaction is also discussed and compared with conventional hydrogenolysis.