The production of light olefins by catalytic cracking of the microalga Isochrysis zhanjiangensis over a modified ZSM-5 catalyst

Abstract

This study investigated the catalytic cracking of the microalga Isochrysis zhanjiangensis over a modified ZSM-5 catalyst with the aim of producing C2–C4 light olefins. Compared with the thermal cracking process, the catalytic cracking of this microalga displayed higher selectivity for and greater yield of these olefins. The catalytic cracking of extracted lipids and the corresponding residues of the microalga was also examined, and the results showed that the lipids could be efficiently converted to light olefins. The catalytic cracking of lipids extracted by different solvents demonstrated that neutral lipids gave the highest yield of light olefins at 36.7%. The yields of light olefins obtained from catalytic cracking of the extraction residues were much lower than the yields obtained from lipids, and thus the lipids, especially the neutral lipids, are the primary contributors to the generation of light olefins. Isochrysis zhanjiangensis with an elevated neutral lipid content will therefore give the highest yield of light olefins through catalytic cracking. The catalytic cracking of a microalga resulted in an 11.0% yield of light olefins. When the neutral lipid content in the microalga was increased to 33.9%, the yield of light olefins was improved to 16.4%.