Impact of membrane material properties on the performance of a combined pervaporation and distillation process for biobutanol concentration

  • Posted on: 11 June 2018
  • By: mmiltner
TitleImpact of membrane material properties on the performance of a combined pervaporation and distillation process for biobutanol concentration
Publication TypeConference Paper
Year of Publication2017
AuthorsKirchbacher F, Miltner M, Friedl A, Wukovits W
Conference Name10th World Congress of Chemical Engineering WCCE10, Barcelona, Spain

A sustainable energy production is one of the main goals of today’s society. Fossil fuels are still the backbone of the energy carrier market and chemical industries. To minimize their use and reduce the impact on climate change biofuels produced from renewable sources are of high interest. Biobutanol offers distinct advantages over other biofuels under consideration. It offers a high energy density compared to other biofuels like ethanol as well as lower corrosiveness and volatility. Furthermore, it can be used in multiple processes as a bulk chemical, for example in chemical synthesis or as a solvent.

Although the production of biobutanol from biomass via acetone-butanol-ethanol (ABE) fermentation is well known, it is not economically feasible at the moment. As the fermentation product contains only 1.5 w% or less butanol due to self-inhibition at 13g/l, direct distillation consumes large amounts of energy. To circumvent this problem pre-enrichment before the distillation is a given necessity. An interesting option for this intermediate step is pervaporation currently under research within the European Union’s Horizon 2020 research and innovation project Waste2Fuels.

Pervaporation is a thermal driven separation process applying dense polymeric membranes. Due to the selective layer of the used membrane and the activity coefficients of solvents in the ABE-water system high separation factors for butanol are observed. Furthermore, compared to distillation in pervaporation only the permeate is evaporated. Although pervaporation generally reduces energy demand in combination with distillation [1], the overall performance of the system strongly depends on membrane properties like selectivity as well as process design specifications like membrane area.

Two different membrane materials – polydimethylsiloxane (PDMS) and polyoctylmethylsiloxane (POMS) – were tested experimentally and further analysed using process simulation applying the commercial software Aspen Plus®. To properly model pervaporation an in-house developed user defined unit operation is implemented and parameterized using the experimental results. Simulation of the distillation was carried out by using the provided Aspen Plus® models. The effect of the membrane materials and process parameters are investigated via sensitivity analysis and case studies. First calculations showed promising results for the POMS membrane. The final results of the simulation as well as technical improvements based on the findings will be presented.