New path in the thermal cracking of triacylglycerols (canola and soybean oil)

Abstract

Triacylglycerols (TGs) are naturally occurring oils abundant in many crops. A series of batch uncatalyzed thermal decomposition experiments were performed using canola and soybean oils to explore pathways of TG cracking. A detailed gas chromatographic protocol based on mass spectrometric identification and flame ionization quantification was applied to the organic liquid product generated upon cracking. Reaction conditions were identified that resulted in a novel organic liquid product (OLP) composition compared to previously reported work. Under these conditions (temperatures within a 420–440°C range) a new route for TG thermolysis was discovered in which cracking reactions of original TG-bound fatty acids were nearly complete and led to the formation of 15–25wt.% C2–C10 linear saturated monocarboxylic acids and ca. 30% linear alkanes. Less than 2wt.% C16–C18 fatty acids which were originally present in the feedstocks as glycerol triesters were found in the OLP. These reactions appear to be kinetically controlled due to abundant hydrogen formation. This route provides a significant enrichment of low-MW compounds in the OLP (65–70wt.% being <C11) and thus may be considered as a new option for the production of replacement products for petroleum-based fuels and chemicals.