Physical properties and their measuring methods of hydrothermal liquefaction bio-crude from microalgae:a review

Hydrothermal liquefaction(HTL) bio-crude from microalgae cannot be directly used as transportation fuels,but can find new applications when integrated with modern petroleum processing techniques. The physical properties of HTL bio-crude from microalgae,including density,viscosity,acidity,elemental composition,heating value,boiling range distribution and average molecular weight,were summarized and compared to heavy crude oil and residue oil. The measuring methods were also briefly introduced. Upgrading of HTL bio-crude from microalgae was reviewed based on comparing various upgrading methods and performances. It is important to point out that compared with heavy crude oil and residue oil,HTL bio-crude from microalgae has similar density and viscosity,higher acidity,lower heating value,higher content of oxygen and nitrogen and high boiling point components and larger average molecular weight. Hydrotreating of HTL bio-crude from microalgae can significantly improve its quality. However,it was constrained by coking of the reactor,high catalysts cost and hydrogen consumption.