Review of recent developments to improve storage and transportation stability of bio-oil

The technology of fast pyrolysis is regarded as a promising route to convert lignocellulose biomass into liquid oil (bio-oil) which can be upgraded to transportable fuels and intermediate chemicals. However, the bio-oil is a complex mixture of organic compounds that are obtained in a non-equilibrium state. Therefore, the physical properties of bio-oil such as density, acidity, viscosity and chemical compositions change during storage and transportation, which is one of the most challenging problems in using bio-oil for any applications including as transportation fuels. This paper summarizes phenomena that lead to unstable properties of bio-oil and reviews recent developments in techniques used to improve the bio-oil properties for making bio-oil a stable intermediate product that can be easily handled and processed.