Pilot plant synthesis of n-propyl propionate via reactive distillation with decanter separator for reactant recovery. Experimental model validation and simulation studies

Successful process intensification (PI) stories applied broadly are the reactive distillation (RD) processes used in esterification syntheses. One application is developed here with the heterogeneously catalyzed synthesis of n-propyl propionate (ProPro) from 1-propanol (ProOH) and propionic acid (ProAc). In this investigation, conventional RD of ProPro was further improved. With the objective to recover product and reactant, an experimental column set-up was equipped with a decanter on top enabling to separate the distillate product into two main streams. The aqueous phase was discharged and part of the organic phase was refluxed back to the column. Experimental results comprising temperature and composition column profiles were obtained in a pilot-scale column (DN-50), equipped with structured packings (Sulzer BX and Katapak-SP 11 with Amberlyst 46™ for the reactive part). For simulation studies a non-equilibrium stage model (NEQ model) was applied which shows satisfactory agreement with the performed experiments. Further theoretical investigations of relevant operating parameters (total feed, molar feed ratio, reflux ratio and heat duty) and their effect on the overall process performance were realized. Studies with the given column configuration showed that product purity in the bottom stream could be increased to w ProPro,bottom = 91.0 % and maximum ProAc conversions to XProAc = 94.5%.