(229c) Process Design and Economic Analysis of the Production of Sucrose Esters Using a Solvent-Free Transesterification

Sucrose esters are biobased surfactants produced from sucrose (from sugar cane) and fatty acid methyl esters (derived from vegetable oils). Due to their properties such as rapid biodegradability, biocompatibility, and biocide potential for certain microorganisms [1], they are used in cosmetic, food and pharmaceutical green products.

Sucrose esters are commonly produced through base-catalyzed transesterification of sucrose and fatty acid methyl esters (FAMEs) under vacuum to remove produced methanol. Depending on the esterification degree of the sucrose molecule, sucrose esters can be produced in a wide range of polarities (i.e. Hydrophilic-Lipophilic-Balance, HLB), which is related with its final application. In the transesterification route, the reactants incompatibility is generally overcome by the use of solvents of medium polarity such as dimethylsulfoxide (DMSO) or dimethylformamide (DMF), in which both reactants are soluble [2,3]. A drawback in the use of these solvents is need of exhaustive solvent removal owing to the health concerns of DMF and DMSO, taking into account the final use of sucrose esters [1,2,4].

An alternative process to overcome the reactants incompatibility is the use of emulsifiers as contact agents in a solvent-free process [5–8]. Our last studies have been focused on the experimental study and kinetic modeling of this heterogeneous reactive system. Operational conditions regarding the optimal particle sizes (of sucrose and catalyst), temperature, reactants ratio, catalyst concentration and contact agent (emulsifier) concentration to maximize the performance of the reaction have been determined.

In the solvent-free transesterification, considerable amounts of non-reactive sucrose and FAME remain on the final mixture. The reported purification processes to obtain commercial sucrose ester propose the use of an organic non-polar solvent to extract the residual FAMEs [9–14]. Then, water or other polar solvent is used to wash the precipitated sucrose esters and to separate them from residual sucrose and catalyst. Our recent studies have been focused on the solvent selection and the determination of the operation conditions of the FAME and sucrose extraction, as well as on the product bleaching.

In this work, results of the previous works were used to propose a process design to produce sucrose esters via solvent-free transesterification. The batch operation and continuous operation were compared in two different process designs. Moreover, the process to produce three different final products: one of high HLB using potassium palmitate as contact agent (SE-KP-72), one of medium HLB using sodium stearate as contact agent (SE-NaS-51), and one of low HLB using sodium stearate as contact agent (SE-NaS-30). For all processes, equipment was selected and sized using the generated experimental information, kinetic models, empirical models and patented operation conditions. Then, correlations were used to calculate capital and operating costs, and the processes were economically assessed using two profitability indicators and the cost distribution. In general, the sucrose ester production using the solvent-free transesterification is competitive compared with the solvent transesterification. Batch and continuous processes showed similar profitability, while products using sodium stearate as contact agent had better values of the economic indicators. Obtained results can be used for the identification of the key design and operation variables affecting the economic viability of the process. These parameters should be further studied and optimized to continue with the process implementation.

References

[1] N. Otomo, Basic properties of sucrose fatty acid esters and their applications, in: D.G. Hayes, D. Kitamoto, D.K.Y. Solaiman, R.D. Ashby (Eds.), Biobased Surfactants Deterg., AOCS Press, Urbana, Illinois, 2009: pp. 275–298.

[2] P.S. Deshpande, T.D. Deshpande, R.D. Kulkarni, P.P. Mahulikar, Synthesis of Sucrose–Coconut Fatty Acids Esters: Reaction Kinetics and Rheological Analysis, Ind. Eng. Chem. Res. 52 (2013) 15024–15033. doi:10.1021/ie401524g.

[3] H.B. Hass, N.J. Summit, F.D. Snell, W.C. York, L.I. Osipow, Process for producing Sugar Esters, 2893990, 1959.

[4] Y. Shi, J. Li, Y.-H. Chu, Enzyme-catalyzed regioselective synthesis of sucrose-based esters, J. Chem. Technol. Biotechnol. 86 (2011) 1457–1468. doi:10.1002/jctb.2711.

[5] K.J. Parker, K. James, J. Hurford, Sucrose Ester Surfactants — A Solventless Process and the Products Thereof, in: J.L. Hickson (Ed.), Sucrochemistry, American Chemical Society, Washington, DC, 1977: pp. 97–114.

[6] J. Fitremann, Y. Queneau, J. Maitre, A. Bouchu, Co-melting of solid sucrose and multivalent cation soaps for solvent-free synthesis of sucrose esters, Tetrahedron Lett. 48 (2007) 4111–4114. doi:10.1016/j.tetlet.2007.04.015.

[7] H.R. Galleymore, K. James, H.F. Jones, C.L. Bhardwaj, Process for the production of a surfactant containing sucrose esters, 4298730, 1981.

[8] G.P. Rizzi, H.M. Taylor, Synthesis of higher polyol fatty acid polyesters, US 3963699, 1976.

[9] K. James, Purification of Sucrose Esters, US 4104464, 1978.

[10] S. Kea, C.E. Walker, Separation and purification of sugar esters synthesized from both aqueous and nonaqueous systems, US 4710567, 1987.

[11] S. Matsumoto, Y. Hatakawa, A. Nakajima, Process for purifying sucrose fatty acid esters, US 5008387, 1991.

[12] S. Matsumoto, Y. Hatakawa, A. Nakajima, Process for recovering unreacted sucrose from reaction mixture synthesis of sucrose fatty acid esters, US 4995911, 1991.

[13] S. Matsumoto, Y. Hatakawa, A. Nakajima, Method of producing powdery high hlb sugar fatty acid ester, US 5144022, 1992.

[14] Y. Koyama, N. Kawase, H. Yamamoto, S. Kawata, Y. Kasori, Process for producing sucrose fatty acid ester, EP 0659760A2, 1994.