Energy saving potential of hybrid membrane and distillation process in butanol purification: Experiments, modelling and simulation

• Three organophilic PV membranes are investigated with the help of DoE.
• Functions for component permeance are regressed for the most promising membrane.
• A PV user defined unit operation is proposed and implemented in AspenPlus.
• Mass and energy balances for total flowsheet and each processes step are calculated.
• Sensitivity analysis reveals energy saving potentials for the combined process steps.

Pervaporation experiments of dilute aqueous butanol solutions were carried out with three PDMS [poly(dimethyl siloxane)] membranes. Based on the experimental results of the best performing membrane a regression for both butanol and water permeability was done in the software R and implemented in a user defined pervaporation unit operation in the software Aspen Custom Modeler. With the implementation of the pervaporation step in Aspen Plus the hybrid pervaporation and distillation purification chain can be simulated in consistent way.Calculation of pervaporation of a 0.5 wt% BuOH-water solution with the experimentally investigated PDMS membrane results in a permeate stream with a concentration of 9 wt% BuOH. Application of membrane distillation resulted in a permeate butanol concentration of only 3 wt% and a considerable higher specific energy demand compared to pervaporation.For product purities of 99 wt% of BuOH a hybrid pervaporation and distillation process saves around 50% of the energy demand compared to state of the art distillation. A sensitivity analysis of the pervaporation step reveals, that for the hybrid pervaporation and distillation process compared to state of the art distillation the energy demand decreases already exceeding 5 wt% BuOH in the permeate stream.