Two-stage thermal conversion of inedible lipid feedstocks to renewable chemicals and fuels

• Thermal hydrolysis–pyrolysis was used to produce hydrocarbon from inedible lipids.
• Feedstock fatty acid composition did not influence organic liquid product yield.
• Organic liquid product had compounds in the gasoline and diesel boiling range.
• The organic liquid product mostly met the CGSB specification for diesel fuel.

The aim of this work was to study the conversion of inedible, low cost lipid feedstocks to renewable hydrocarbons using a two stage thermal hydrolysis–pyrolysis method. Beef tallow, yellow grease, brown grease and cold pressed camelina oil were first hydrolyzed and the fatty acids produced were recovered and pyrolyzed in batch reactors. The pyrolysis products were identified and quantified using gas chromatography and mass spectrometry. The pyrolysis product yields were similar for all the feedstock used with the organic liquid fraction (OLF) accounting for 76–80% of the product. The OLF consisted predominantly of n-alkanes. Approximately 30% OLF constituted a gasoline-equivalent fraction and 50% a diesel fraction. Other fuel property test showed that the OLF met the specifications set out by the Canadian general standards board. This research demonstrated a novel two-stage thermal hydrolysis–pyrolysis conversion method for producing OLF from inedible and low-value lipids.