Fast microwave-assisted pyrolysis of microalgae using microwave absorbent and HZSM-5 catalyst

Fast microwave-assisted pyrolysis (fMAP) in the presence of a microwave absorbent (SiC) and catalyst (HZSM-5) was tested on a Chlorella sp. strain and on a Nannochloropsis strain. The liquid products were characterized, and the effects of temperature and catalyst:biomass ratio were analyzed. For Chlorella sp., a temperature of 550 °C, with no catalyst were the optimal conditions, resulting in a maximum bio-oil yield of 57 wt.%. For Nannochloropsis, a temperature of 500 °C, with 0.5 of catalyst ratio were shown to be the optimal condition, resulting in a maximum bio-oil yield of 59 wt.%. These results show that the use of microwave absorbents in fMAP increased bio-oil yields and quality, and it is a promising technology to improve the commercial application and economic outlook of microwave pyrolysis technology. Additionally, the use of a different catalyst needs to be considered to improve the bio-oil characteristics.