Valorization of microalgae: Efficient conversion of Chlorella sp. biomass into ethyl levulinate

Microalgae have significant promise as sustainable bioresources for the synthesis of biofuels, biochemicals, and biomaterials. This study synthesized ethyl levulinate (EL) by thermochemical conversion of microalgae using methanesulfonic acid (MSA) as a catalyst. To optimize the conversion factors influencing the synthesis of EL from microalgae, the one-factor-at-a-time technique was applied to the reaction performed in ethanol media. The addition of water to the reactant strongly inhibited the formation of EL. Under the optimized conditions of 2.5 % microalgae biomass with 0.5 M MSA at 170 °C for 45 min, a 65.76 ± 0.57 % EL yield carbohydrate content basis (34.31 ± 0.30 % based on biomass amount) was achieved. Furthermore, the EL yields increased linearly with the combined severity (CS) until 3.4 and then slightly declined thereafter. The highest yields were achieved near CS 3.4. The results indicated that microalgae, which are easily accessible and potentially significant bioresources, together with MSA, an ecologically benign and highly effective acid catalyst, might be used for the production of promising biorefinery products.