Pyrolysis of Macroalgae and Its Residue for Bio-oil

Abstract

Biofuels from renewable biomass sources, with zero net CO2 emissions, are considered the most promising substitute for the limitedness of fossil fuels. Furthermore, biofuels, which can be produced via bio-oil upgrading and refining, are proven to be less polluted than fossil fuels. This review evaluates the quantity and quality of bio-oil produced from the pyrolysis of macroalgae biomass and macroalgae residue. The maximum yield of bio-oil is dependent on a number of factors, including the moisture content of the biomass, the ash content of the biomass, the pyrolysis temperature, and the vapor residence time. Macroalgae with a high ash content produce little bio-oil and produce a lot of biochar via secondary tar reactions. In comparison, the increased presence of alkali metals in pyrolysis has significantly increased bio-oil production. Studies showed that the calorific value (HV) of bio-oil produced from the pyrolysis of macroalgae is higher than the calorific value (HV) of macroalgae biomass. The quality of bio-oil can be improved through a catalytic process by removing oxygen and nitrogen to obtain high-efficiency biofuels. When considering the content of C-organic in the macroalgae as the feasibility basis of bio-oils sources, solid waste of Gracilaria sp. with C-organic content at 13.93% has high potential to be used as a raw material for bio-oil.