Study of KOH/Al2O3 as heterogeneous catalyst for biodiesel production via in situ transesterification from microalgae

Heterogeneous KOH/Al2O3 catalysts, synthesized by the wet impregnation method with different KOH loadings (20-40 wt%) and calcination temperatures from 400 degrees C to 800 degrees C, were used to produce biodiesel from Chlorella vulgaris biomass by in situ transesterification. The highest yield of biodiesel of 89.53 +/- 1.58% was achieved at calcination temperature of 700 degrees C for 2 h and 35 wt% loading of KOH, and at the optimal reaction condition of 10 wt% of catalyst content, 8mL/g of methanol to biomass ratio and at 60 degrees C for 5 h. The characteristics of the catalysts were analysed by X-ray diffraction, scanning electron microscopy and Brunauer-Emmett-Teller.