Catalytic hydrothermal liquefaction of Gracilaria corticata macroalgae: Effects of process parameter on bio-oil up-gradation

Hydrothermal liquefaction (HTL) of Gracilaria corticata (GC) macroalgae was studied over a series of nickel-iron-layered double oxides (NiFe-LDO) supported on activated bio-char catalysts at 280 degrees C and different solvents medium. Maximum bio-oil yield (56.2 wt%) was found with 5%Ga/NiFe-LDO/AC catalyst at 280 degrees C under ethanol solvent. The catalytic HTL up-gradation decreased the bio-char yield significantly. However the bio-oil quality significantly improved with using the 5%Ga/NiFe-LDO/AC catalyst. Also, improved performance with higher amount of bio-oil and lower amounts of bio-char and gas were achieved, which is due the several reactions happening during the HTL process. Catalytic HTL also revealed that introducing NiFe-LDO nanosheets into the activated char could result in NiFe-LDO/AC catalysts of higher surface area and increased active sites. Being impregnated by 5%Ga, catalysts with improved acid sites and thereby, advanced deoxygenation and aromatization activities were achieved. Hence Ga/NiFe-LDO/AC could be considered as a promising catalyst HTL bio-oil upgrading.

Automated summary

The study demonstrates that using Ga/NiFe-LDO/AC catalyst can lead to higher bio-oil yield, reduced bio-char and gas production. Catalytic HTL upgrading significantly improves the quality of bio-oil, making the catalyst have more active sites and surface area.