Biodiesel production from sheep fat catalyzed by CaO-SrO(x)/BCs(y) acid-base bifunctional catalyst and process optimization

In this study, an environmentally friendly and recyclable acid-base bifunctional CaO-SrO/biomass chars (BCs) catalyst was prepared using egg shells and poplar leaves as the base materials, and it was used to transesterify waste sheep fat into biodiesel. The structure and properties of the catalysts were investigated by EDX/SEM, BET, NH3 TPD, and XRD analyses. Biodiesel yield was optimized for maximum values using RSM and ANN. The highest biodiesel yield of 98.83 % was achieved at a catalyst amount of 6 wt%, an alcohol-oil ratio of 8:1, a reaction time of 1.5 h, and a reaction temperature of 65 °C. The catalyst maintained 80.3 % yield after five cycles and showed good acid resistance. By studying the thermodynamics and kinetics behavior of transesterification, the results showed that the doping of SrO reduced the activation energy of the reaction, the activation energy of the reaction is 45.38 kJ/mol. These results show the great potential of our catalyst in transesterification reactions. In addition, the quality of sheep fat biodiesel meets the ASTM D6751 standard. In a life cycle cost analysis, it is shown that our process is relevant for the scale-up and to industrialize of biodiesel production.