Title : Process intensification for the production of 2, 2-dimethoxypropane using Fixed BED Chromatographic Reactor (FBCR)
Abstract:
Introduction: 2,2-Dimethoxypropane (DMP) is a crucial intermediate in vitamin synthesis and serves as an effective water scavenger. The conventional synthesis of DMP from methanol and acetone is characterized by an equilibrium-limited reaction, yielding water as a byproduct, with equilibrium conversion rates typically below 5%. Traditional batch reactors are highly energy-intensive due to low one-pass conversion rates. In this study, we introduce a multifunctional reactor, specifically a Fixed Bed Chromatographic Reactor (FBCR), to facilitate the synthesis of DMP. Notably, we explore the innovative use of non-polar solvents to enhance productivity in reactive chromatography. Employing dry Amberlyst-15 as a catalyst, we demonstrate that the FBCR allows for simultaneous reaction and chromatographic separation, resulting in a remarkable 2.5-fold increase in reaction productivity. This approach not only optimizes the synthesis process but also significantly reduces energy consumption, marking a novel advancement in the production of DMP.
Experimental procedure: A tubular reactor filled with catalysts can act as FBCR reactor, and an additional cooling jacket is provided to maintain the internal temperature of the reactor. The packing density is maintained such that there will be free movement of feed material and the channeling effect can be eliminated. Amberlyst-15 dry has a relatively high affinity towards water. Hence, it gets adsorbed on the catalyst and the reaction moves in the forward direction according to Le Chatelier's principle. After the reactor bed is saturated with water, the catalyst is regenerated using one of the reactants that is methanol. The use of one of reactant is helpful in terms of the separation and purity of the desired product. This reaction is carried out at a sub-ambient temperature, we have carried out experiments at 5 degrees Celsius. We observed a vital role of solvent in this reaction and hence we studied reaction performance with various solvents, we found that non-polar solvents increased productivity considerably, and n-decane was one of the productive solvents for this reaction in FBCR. The use of solvent in FBCR is the first time introduced. The solvent extracts product from the reaction phase and by that increase’s overall productivity. Experiments were performed to optimize the reaction conditions. The solvent can be recovered by distillation. We have estimated adsorption parameters for all compounds in the reaction mixture using multicomponent Langmuir adsorption isotherm, The Langmuir adsorption isotherm is used to describe the equilibrium between adsorbate and adsorbent system, for that binary nonreactive pair adsorption experiments were done in the same reactor.
Result and discussion: We found that water has a maximum adsorption coefficient and n-decane has a minimal adsorption coefficient. The reaction kinetics was studied to get kinetic parameters for this reaction. These the adsorption and kinetics parameter we have used for overall process development. Based on product purity, solvent consumption, and energy required, we found n-decane to be one of the best solvents; it does not form azeotrope and can be easily separated using distillation. Methanol can be conveniently used as a catalyst regeneration solvent. We did not observe any considerable difference in catalytic activity even after 10 successive cycles. To design FBCR and its corresponding continuous counterpart i.e. Twin tower chromatographic reactor, kinetic and adsorption parameters are used. Downstream distillation separation sequencing is done using aspen simulator and we can get 98% pure DMP product. Reactants and solvents recycled back to the feed. A novel process is developed for continuous synthesis of DMP, this process will be less energy-intensive and more productive.
Conclusion: Synthesis of 2,2-dimethoxypropane (DMP) using a continuous Fixed Bed Chromatographic Reactor (FBCR) with n-decane as a reaction solvent demonstrates significant improvements in energy efficiency and reaction yield. This innovative approach not only reduces the energy demands typically associated with conventional batch processes but also enhances the overall productivity of DMP synthesis. The integration of non-polar solvents in this system represents a notable advancement, paving the way for more sustainable and efficient processes in fine chemical manufacturing.
