Synthesis of dimethyl carbonate and propylene glycol in a pilot-scale reactive distillation column: Experimental investigation, modeling and process analysis

Abstract

The transesterification of propylene carbonate with methanol to produce the two valuable products dimethyl carbonate and propylene glycol is associated with an unfavorable chemical equilibrium and complex thermodynamic behavior. This results in a challenging and cost-intensive process currently used for their production. The application of reactive distillation, which integrates chemical reaction and distillation into one single column is considered as potential candidate to improve efficiencies and product yields within chemical-equilibrium-limited systems. However, the design of such a column for industrial-scale applications is challenging as it needs the integration of model-based approaches with reliable experimental data. This paper presents an experimental and theoretical investigation of the simultaneous production of dimethyl carbonate and propylene glycol in a pilot-scale reactive distillation column. Experiments varying decisive operating parameters were successfully performed showing the feasibility of simultaneously producing dimethyl carbonate and propylene glycol in a reactive distillation column. The experimental results were used to select and validate a modeling approach for the simulation of the reactive distillation process. The successfully validated non-equilibrium stage model was applied to perform a process analysis pointing out the trends of both the reactant conversions and the product purities. The simulation results showed the option of achieving high propylene carbonate conversions while recovering an azeotropic mixture of dimethyl carbonate and methanol in the distillate. These results define the operating range for the economic optimization and establishment of an industrial-scale reactive distillation process for this chemical system.