Catalytic hydrothermal liquefaction of microalgae over reduced graphene oxide support Ni catalyst.

In this study, a reduced graphene oxide (RGO) material loaded with nickel was prepared, and to the best of the authors' knowledge, it was the first time that RGO material used as a catalyst in the hydrothermal liquefaction (HTL) of microalgae. The effect of RGO support Ni catalyst on the yield and quality of bio-oil derived from HTL of Spirulina was studied in this research. The results showed that the catalyst could improve the yield of bio-oil, and the performance in improving the quality of bio-oil was significantly increased. GC–MS analysis showed that RGO catalyst could promote the formation of hydrocarbons. When the loading amount of Ni was 5%, the oxygen content of bio-oil was the lowest (14.79%), and when the loading amount of Ni was increased to 25%, the content of hydrocarbons was the highest (11.41%). In addition, RGO catalyst also increased the content of low boiling point components (<400°C) in bio-oil from 68% to 81%. This study can provide valuable information for the further application of graphene in microalgae HTL and the production of high-quality bio-oil in the future. • The first time that RGO material used as the catalyst in hydrothermal liquefaction. • The catalyst significantly increased the yield of hydrocarbons and changed the composition of bio-oil. • The mechanism was explored that the catalyst significantly promoted hydrolysis and decarboxylation. [ABSTRACT FROM AUTHOR]