Re-homogenization of phase separated forest residue pyrolysis oil by blending

Abstract The forest industry sector generates a large amount of low quality wood fractions, known as forest residues, which represent a significant potential resource for cheap bioenergy production. A feasible thermochemical route for valorisation of forest residues is fast pyrolysis. Phase separation is one of the main disadvantages of fast pyrolysis liquids as compared to conventional fossil fuels. In this work it is demonstrated that it is possible to homogenize even naturally aged phase-separated forest residue pyrolysis oil by blending with alcohol (methanol or 1-butanol), obtaining a single-phase fuel suitable for heating and power applications. Differences in homogenization mechanism have been found depending on which alcohol is used. Water content analysis and light microscopy were found to be useful techniques for detailed assessment of homogeneity and storage stability of pyrolysis oil/alcohol blends. Light microscopy is a rigorous and time consuming technique but it allows detection of in-homogeneities in a sample which water content analysis may miss.