Solketal Production via Solvent-Free Acetalization of Glycerol over Triphosphonic-Lanthanide Coordination Polymers

Biodiesel is one of the most significant and valuable alternatives to fossil fuels. In the process of transesterification to produce biodiesel from various feedstocks, glycerol is one of the side products obtained, in a high glycerol: biodiesel weight ratio (1:10). Therefore, the growing world demand for biodiesel prompted a glycerol surplus. It is, thus, of interest to find new and added-value paths for the transformation of this abundant chemical. One of the most auspicious glycerol applications is the production of fuel additives, namely cyclic acetals and ketals, from aldehydes and ketones, respectively. In this work, coordination polymers based on nitrile (trimethylphosphonic acid) and Ln3+/Eu3+ are used as catalysts for the acetalization of the bio-renewable glycerol into oxygenated fuel additives. Solketal is the major product obtained from the reaction of glycerol with acetone. This product improves the cold flow properties, lowering the viscosity of biodiesel, improving combustion, and boosting the octane number. The stability of the materials is studied as well as their recovery and reuse.