Recovery utilization of triolein for producing short chain alkane by combining biocatalysis and inorganic catalysis

The production of waste cooking oil (WCO) has been increasing year by year and brought the serious environmental problems. A considerable research effort has been focused on the reuse of WCO. Utilizing the triolein existing in great quantity on olive oil and rapeseed oil is an effective strategy to realize the reuse of WCO. This work introduces a novel process for producing short-chain alkane from triolein based on the convenience of products separation. The continuous process including the hydrolysis of triolein into fatty acid by lipase, the oxidation of fatty acid for producing short-chain fatty acid, and the light-driven decarboxylation of short chain fatty acids was established to produce alkane. The feasibility of the proposed process was demonstrated using model substances. The influences of various operational parameters on hydrolysis, oxidation, and decarboxylation using model substances were studied systematically. The optimized yields of the hydrolysis, oxidation, and decarboxylation reactions were 78.7%, 52.1%, and 78.9%, respectively. The free lipase is reused under the optimal condition and observed that 31.9% decay in catalytic activity even 5 cycles. Immiscible reaction systems are used to facilitate separation of products. The decarboxylation with decarboxylase (CvFAP) for short-chain fatty acid lead to higher alkane yields in 15 min. In addition, the octane yield of 16.2% using triolein as the raw material was obtained in the continuous process. Although this approach results in a low total yield of gasoline, it highlights the potential applications in the production of hydrocarbon fuel with WCO.