Preparation and performance investigation of a lignin-based solid acid catalyst manufactured from olive cake for biodiesel production

The results revealed that a sulfonated lignin-derived acid catalyst has a high potential to esterify waste vegetable oil to about (92%) conversion. Furthermore, it demonstrated about 57% conversion to fatty acid methyl esters (FAME) under the following optimum condition: sulfonation time of 1 h, catalyst loading of 10 wt %, the methanol-to-WVO molar ratio of 35:1, a reaction temperature of 65 °C and reaction time of 6 h. Also, the results showed that the lignin-based acid catalyst can be reused at least ten times with high FFA conversion (>75%).