Process Intensification with a Polar Solvent in Liquid Phase Methanol Synthesis

The effects of various operating and design parameters in reactive distillation for methanol synthesis using a polar solvent (tetraglyme) and Cu-Zn-Al2O3 catalyst on the process performance are investigated in this simulation work. It is observed that trade-offs exist between the reaction (reactant conversion) and separation (methanol purity) as these parameters are varied. The most sensitive parameters are the solvent flow rate, temperature of feed streams, reflux ratio, and cooling duties on the stages. Following the parametric studies, optimization of the RD column was performed to maximize the methanol production and recovery. The optimum case resulted in a methanol productivity of 2.7 mol/kg(catalyst) h which is an increase of 12.5%, and CO and H-2 conversions of 44% and 31% vis-a-vis 39% and 28%, respectively, in the base case. The product purity in the distillate for the optimum case also improved to 87% from 82.4% in the base case. The observed catalyst loading in the optimum cases is explained on the basis of the approach to equilibrium for the methanol synthesis reaction. Based on comparison with the conventional packed bed reactor, it is concluded that a more active catalyst for liquid phase methanol synthesis is needed to make RD competitive in terms of methanol productivity.

Automated summary

By investigating and optimizing the operating and design parameters of reactive distillation, the production efficiency and product purity of methanol synthesis can be significantly improved. It is important to balance the trade-offs between reaction and separation, and adjust various parameters accordingly to achieve the best results.