Synthesis of oxygenated compounds using the simulated moving bed reactor: Synthesis of the acetal 1,1-diethoxybutane.

Nuno Graça, Mehabub Rahaman, Aida Delgado, Carla Pereira and Alírio Rodrigues
The application of integrated separation/reaction processes such Simulated Moving Bed Reactor (SMBR) has shown good results in the production of acetals such as 1,1- dimethoxyethane [1], 1,1-diethoxyethane [2] and 1,1-dibutoxyethane [3]. The present work describes the complete procedure for the application of the SMBR process in the synthesis of the acetal 1,1-diethoxybutane (DEB) from the direct acetalization of butyraldehyde with ethanol using as catalyst/adsorbent the ion-exchange resin
Amberlyst-47®. The first step was the determination of reaction thermodynamic and
kinetic data, this was achieved by performing a set of batch reactor experiments at different temperatures (293 K, 303 K, 313 K and 323 K) , catalyst weight (0.5wt%,
1wt% and 1.5wt%) and reactants molar ratio (2.1, 3.1 and 4.1). A complete batch reactor mathematical model was used to simulate the operation. The reaction thermodynamic and kinetic data were obtained using both experimental data and mathematical model. For this reaction the estimated reaction enthalpy and activation energy are -8.6 kJ/mol and 37.9 kJ/mol, respectively.
Adsorption/desorption experiments with the non-reactive pairs were performed in a fixed-bed column at 303 K packed with the Amberlyst-47®. The data obtained allowed to determine the parameters of the multicomponent Langmuir isotherm used to describe the adsorption equilibrium. Reaction experiments were performed by feeding the column with the reactive mixture (ethanol and butyraldehyde). The reaction data was used to validate the fixed-bed reactor mathematical model.
The feasibility of the application of SMBR in the synthesis of DEB was studied using a mathematical model of the process comprising the reaction, adsorption and mass transfer data obtained.
References
[1] G.K. Gandi, V.M.T.M. Silva and A.E. Rodrigues, Process development for dimethylacetal synthesis: Thermodynamics and reaction kinetics. Ind. Eng. Chem. Res., 44 (2005), 7287-7297.

[2] V.M.T.M. Silva and A.E. Rodrigues, Kinetic studies in a batch reactor using ion exchange resin catalysts for oxygenates production: Role of mass transfer mechanisms. Chern. Eng. Sci., 61 (2006), 316-331.

[3] N.S. Gra9a, L.S. Pais, V.M.T.M. Silva and A.E. Rodrigues, Oxygenated biofuels from butanol for diesel blends: Synthesis of the acetal 1,1-dibutoxyethane catalyzed by amberlyst-15 ion-exchange resin. Ind. Eng. Chern. Res., 49 (2010),

6763-6771.