(136g) Carboxylation of Glycerol in a Biodiesel Plant

Conversion of glycerol into value-added chemicals has emerged in recent years as a result of glycerol's bioavailability, and renewability [1]. About one kilogram of glycerol is produced for every ten kilograms of biodiesel. Glycerol is also produced during soap manufacturing, fatty acid production, and fermentation of sugars directly or as a by-product of the ethanol production from lignocelluloses. Selective glycerol-based catalytic processes [2], such as oxidation, hydrogenolysis, dehydration, esterification, and carboxylation, can produce polymers, ethers, and various fine chemical compounds including hydrogen and glycerol carbonate. Glycerol reacts with carbon dioxide at 5 MPa and 450 K in presence of Sn-catalysts (n-Bu2Sn(OMe)2, n-Bu2SnO or Sn(OMe)2 ), using either glycerol or tetraethylene glycol dimethyl ether as reaction medium to produce glycerol carbonate [1,2]. Glycerol carbonate is an intermediate chemical with many potential areas of application, such as: - reactive protic solvent, a substitute for ethylene carbonate, propylene carbonate; - cyclocarbonate derivatives: solvents for battery electrolyte, filming lubricants, filming plastifiers, agrosynthons, ingredients for cosmetics, and monomers for polymerization. It is also a novel component of gas separation membranes, coatings, paints and surfactants. It can act as a nonvolatile reactive solvent for several types of materials. In addition, it could serve as a source of new polymeric materials for the production of polycarbonates and polyurethanes. Glycerol carbonate could also be used to produce glycidol, which can be used to prepare special types of polyurethanes or it can serve as surfactant. This paper analysis a process of conversion of triacylglyceride and carbon dioxide into biodiesel and glycerol carbonate at an industrial scale. Carbon dioxide from bioethanol plants is used in the process. Rate based distillation columns are used in the purification of glycerol. Aspen Plus based block flow diagram, and process flow diagrams [3] are simulated for an optimal design of the plant. The analysis shows that an optimized biodiesel plant with glycerol carbonate production can be a more economically feasible operation.

1. Guerrero-Perez, M.O., Rosas, J.M. Bedia, J., Rodriguez Mirasol, J., Cordero, T., Recent inventions in glycerol transformations and processing, Recent Patents in Chem. Eng. 2 (2009) 11-21. 2. Aresta, M., Dibenedetto, A., Focito, F., Pastore, C., A study on the carboxylation of glycerol to glycerol carbonate with carbon dioxide: The role of the catalyst, solvent and reaction conditions, J. Molecular Catalysis A: Chemical 257 (2006) 149-153 3. Nguyen, N., Demirel, Y., Retrofit of distillation columns in biodiesel production plants, Energy, The Int. J. 35 (2010) 1625-1632.