The modified supercritical media for one-pot biodiesel production from Chlorella vulgaris using photochemically-synthetized SrTiO3 nanocatalyst

In this research, a one-pot production of biodiesel, hydrocarbons, oxygenates, and aromatics form Chlorella vulgaris was performed in supercritical methanol without catalyst and in the presence of TiO2 and SrTiO3 nanocatalysts. The reaction in the presence of SrTiO3 showed the highest production yield of fatty acid methyl esters (FAMEs). The co-solvents water, chloroform, diethyl ether, and n-hexane were used for modifying the supercritical medium to affect the product yields in SrTiO3-catalyzed process. The SrTiO3 nanocatalyst was photochemically prepared and the leaching of catalysts into the products was evaluated. Results showed that for all products except oxygenates, the addition of diethyl ether and chloroform to methanol had a slightly positive effect on the production yields. For all products, n-hexane co-solvent showed the best performance with production yields of 16.65, 2.42, 2.12, and 0.57 mg.g−1biomass for FAMEs, oxygenates, hydrocarbons, and aromatics, respectively. Furthermore, the water showed no significant effect on production yields except in the case of oxygenates. The results may be due to the high ability of n-hexane for dissolving the biomass in the reaction condition. Also, the ICP-OES detected no trace amounts of catalyst in the final product and it confirms that the photochemical method for catalyst preparation can prevent the catalyst leaching.