Enhanced biobutanol separation by a heat pump assisted azeotropic dividing-wall column

Stronger sustainability needs for the production of fuels and chemicals have spurred extensive research to substitute fossil fuel sources by renewable sources. Yet, the major cost of biorefineries is in the downstream processing. This issue has to be addressed properly to make biofuels an economically viable alternative. As a renewable fuel, biobutanol is produced from biomass feedstocks. But after the fermentation step it has a very low concentration (less than 3 %wt) that leads to high energy requirements for onventional downstream separation. To reduce the energy penalty, we describe here a new hybrid separation process based on a heat pump assisted azeotropic dividing-wall column (A-DWC). CAPE tools and Pinch analysis were used for the process synthesis, design and optimization of the process. The plant capacity considered here is 40 ktpy butanol (99.4 %wt). Remarkably, the energy requirement for butanol separation using heat integration and vapour recompression assisted A-DWC is reduced by 58% from 6.3 to 2.7 MJ/kg butanol.