Catalytic Hydrothermal Liquefaction of Algae for Production of Bio-oil with Solid Superacid Catalyst SO42−/ZrO2

Solid superacid SO42−/ZrO2 as heterogeneous catalyst was prepared to upgrade the bio-oil in the progress of hydrothermal liquefaction (HTL) for the represented algae of Chlorella vulgaris and Enteromorpha prolifera. The solid superacid catalyst could obviously adjust the composition of the bio-oil and improve the higher heating values (HHVs). The catalytic performance could be regulated by adjusting the acid amount and acid strength of SO42−/ZrO2. Furthermore, it was explored the catalytic effects of SO42−/ZrO2 by the HTL for algae major model components, including polysaccharides, proteins, lipids, binary mixture and ternary mixture. The results showed that the introducing of SO42−/ZrO2 catalyst could increase the yields of bio-oil from proteins and lipids, and avoid the Maillard reaction between polysaccharides and proteins. Moreover, a possible reaction pathway and mechanisms has proposed for the formation of bio-oils from HTL of algae catalyzed by SO42−/ZrO2 based on the systematic research of the producing bio-oil from major model components.