An energy efficient route for the dehydration of 2-Methylpropan-2-ol: Experimental investigation, modeling and process optimization

Abstract

Abstract In the prospect of bio-refinery industries and escalating demand towards renewable energy resources, etherification of glycerol with 2-Methylpropan-2-ol (2M2P) could be a promising solution to supersede conventional petroleum derived fuel additives. However, the presence of water in 2M2P restricts its applicability as an etherifying agent to produce tert-butyl ethers of glycerol. Thus, a novel and energy efficient Saline Entrainer Extractive Distillation (SEED) process is investigated for the dehydration of 2M2P, which utilizes an organic solvent: glycerol and an inorganic salt: MgCl2, as an effectual combined entrainer. The present work exhibits a practical approach towards the design and optimization of SEED based on a suitable thermodynamic model. In this context, phase equilibrium data was determined for different binary systems in consideration. The symmetric eNRTL thermodynamic model was found to best describe the experimental data. The modeled parameters successfully demonstrated the feasibility of the proposed process in terms of ternary; 2M2P + water + glycerol and quaternary; 2M2P + water + glycerol + MgCl2 system. The preferential energetic interaction of MgCl2 with glycerol and water modifies the phase equilibrium, thereby eliminating the azeotrope of 2M2P + water system. In addition, the SEED process was successfully implemented at laboratory-scale which resulted in 99.5 wt% of 2M2P. Finally, based on process design and optimization, a reduction of 30.5% in energy, 44.7% in capital expenditures and 50% in number of stages was obtained with the use of combined entrainer as compared to glycerol as an entrainer in the dehydration process.