Synthesis and characterization of carbon-based MgO catalysts for biodiesel production from castor oil

The main purpose of this work was to develop a highly efficient and stable solid base catalyst for the preparation of biodiesel to meet the needs for green and clean production. To this end, a series of carbon-based magnesium oxide (MgO) solid base catalysts with high specific surface area were prepared by a sol-gel method and calcination for biodiesel production from castor oil. The effects of different organic additives and calcination temperatures on the physicochemical properties of catalysts were analyzed and evaluated by XRD, SEM, EDX, BET, FTIR and TGA. SEM and BET results indicated that the carbon-based MgO catalysts have a proper particle size distribution and a higher specific surface area. Meanwhile, EDX and TG analysis evidenced the presence of residual carbon in the MgO samples, which was confirmed to have a positive effect on the performance of the catalysts. The transesterification reaction was carried out in a batch reactor with condensed reflux to assess the performance of the catalysts. The MgO-UREA-800 catalyst exhibited impressive catalytic performance and an optimum biodiesel yield of 96.5% was obtained at the molar ratio of ethanol to oil of 12: 1, catalyst loading of 6 wt%, reaction temperature of 75 degrees C and reaction time of 60 min. The catalyst durability tests showed that the catalysts could be reused in five cycles of operation without significant losses in activity.