Improvement of bark pyrolysis oil and value added chemical recovery by pervaporation

Pyrolysis oil produced from forestry residues is used as a low-grade fuel in applications such as heating oil. However, the high water and acid content can lead to fuel instability, phase separation, poor lubrication, and corrosion. In this work, pervaporation has been studied as a process to simultaneously upgrade a pyrolysis oil produced from Canadian softwood bark to meet a boiler fuel standard and extract value-added chemicals. Commercial polyacrylonitrile-supported polyvinyl alcohol membranes from DeltaMem AG were used at temperatures of 60 and 80 degrees C to separate water and volatile organic components, including methanol, acetic acid, and acetol. A design of experiment study was used to define the range of operating conditions. A temperature of 80 degrees C and a low feed flow rate of 0.1 mL min(-1) resulted in the highest quality oil. The upgraded pyrolysis oil (pervaporation retentate) showed an increased heating value from incomplete combustion to 16.07 MJ kg(-1) and the water content was lowered from 70.2 wt% in the feedstock to 21.4 wt%, demonstrating the potential for this process on a larger scale.