Elucidation of the catalytic cracking pathway for unsaturated mono-, di-, and triacylglycerides on solid acid catalysts

Abstract

Heterogeneous catalytic transformation of lipids to transportation fuels offers a unique opportunity to provide sustainable energy while utilizing the current petroleum refining infrastructure. The reaction chemistry for the heterogeneous catalytic cracking of unsaturated acylglycerides was studied. Mono-, di-, and triolein, which are acylglycerides with oleic acid as the fatty acid constituent, were reacted at 400 °C over H +ZSM-5, faujasite, and silica–alumina catalysts. Reactions were carried out using a pulse-type microreactor utilizing online GC analysis. This technique allowed real time evaluation of reaction products using mass spectrometry and quantitation using a thermal conductivity detector. Selected products of these reactions were further reacted in an effort to elucidate the reaction pathway for producing green fuels from unsaturated lipids. The results indicated the removal of the heteroatom from the oxygenated feedstock by formation of CO and CO 2. The shape-selective zeolite catalysts (i.e. H +ZSM-5 and faujasite) promoted the formation of aromatic compounds as tertiary cracking products. Silica–alumina, an amorphous catalyst, promoted the formation of linear dienes. A reaction scheme has been proposed for the deoxygenation of lipid compounds. These results reveal the potential of using lipid feedstocks for transportation fuels.