(577g) Transesterification of Propylene Glycol Methyl Ether Using Heterogeneous and Homogeneous Catalyst in Simulated Moving Bed Reactor

Authors: 
Oh, J., Georgia Institute of Technology
Sreedhar, B., The Dow Chemical Company
Donaldson, M., Georgia Institute of Technology
Schultz, A., The Dow Chemical Company
Frank, T. C., The Dow Chemical Company
Bommarius, A., Georgia Institute of Technology
Kawajiri, Y., Georgia Institute of Technology
Reactive chromatography is an integrated process that combines reaction and separation in a single unit that leads to a higher productivity. This process is especially advantageous when the reaction is equilibrium limited where in-situ separation of product shifts the equilibrium in the direction of conversion increase. A continuous reactive separation process, simulated moving bed reactor (SMBR), utilizes this principle in a train of multiple chromatographic columns that are packed with an adsorbent that also acts as a catalyst.

In the present work, we study SMBR for the catalytic synthesis of propylene glycol methyl ether acetate using two types of catalysts: AMBERLITEâ?¢ IRA-904 and sodium alkoxide. Heterogeneous catalyst, AMBERLITEâ?¢ IRA-904, has an advantage of not requiring the separation of catalyst from the product. On the other hand, the homogeneous catalyst, sodium alkoxide, shows a higher activity for the transesterification and also deactivation of catalyst is prevented by continuously feeding fresh homogeneous catalyst into the system. The benefits of each catalyst are discussed with comparisons throughout the study.

Case studies of process development for the ester product are discussed using heterogeneous and homogeneous catalysts. For heterogeneous catalysis, AMBERLITEâ?¢ IRA-904 is employed that acts both as catalyst and adsorbent. When homogeneous catalyst was used, AMBERLITEâ?¢ IRA-904 in an inactive ionic form was used as a packing material that functions as an adsorbent. Equilibria and kinetics of the reaction and adsorption are investigated by carrying out batch reaction experiments and chromatographic pulse tests. Model parameters are obtained from batch experiments by the inverse method, where a transport dispersive model with a linear driving force for the adsorption rate is used for modeling. Using parameters obtained from the experiments, the SMBR is designed and optimized considering multiple objectivesâ??to maximize the production rate of DOWANOLâ?¢ PMA glycol ether acetate, to maximize the conversion of the transesterification reaction, and to minimize the consumption of the excess reactant, DOWANOLâ?¢ PM glycol ether, which also acts as the desorbent in the chromatographic separation. The two SMBR processes are compared systematically at the optimal operating conditions.

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