Desulphurization of drop-in fuel produced through lipid pyrolysis using brown grease and biosolids feedstocks

Biosolids can be incorporated as a water replacement into a two-stage thermal process for biofuel production from brown greases, significantly reducing the overall environmental impact of the process. Unfortunately, the use of biosolids resulted in an appreciable amount of sulphur in the pyrolytic oils produced in the final stage of the process. Here, we first evaluated the relationship between the sulphur content of fatty acids pyrolysis liquid products and pyrolytic conditions. Afterwards, we evaluated the sulphur removal efficiency of several approaches such as distillation, extraction and adsorption. Through a combination of distillation and liquid-liquid extraction, we achieved a desulphurization of up to 95% reaching a final sulphur concentration of 15 ± 4 ppm.