Carbon-based solid acid catalyst from de-oiled canola meal for biodiesel production

Abstract A carbon-based acid catalyst was prepared by the sulfonation of partially carbonized de-oiled canola meal (DOCM), a by-product of canola seed processing. Partial carbonization of DOCM was carried out at 300 and 400 °C and the partially carbonized material prepared at 400 °C was steam activated to improve its surface properties. Four types of carbon catalysts were prepared using the partially carbonized material and DOCM by concentrated sulfuric acid treatment. The spectral and elemental analysis clearly indicated that the catalyst had enough acidic sites in the form of sulfonate groups having the ability to promote esterification reaction. The catalyst partially carbonized at 300 °C established various functional groups such as aromatic carbon atoms, phenolic-OH, COOH, and carbonyl groups on the surface as evidenced by the MAS 13 C NMR and FTIR spectra. The catalyst produced by partial carbonization at 300 °C followed by sulfuric acid treatment showed better performance towards esterification of oleic acid and high FFA canola oil. The maximum conversion reached 93.8% after 24 h at 65 °C using 1:60 mol:mol of FFA to methanol and 7.5 wt.% of catalyst to FFA. The performance of the catalyst was reduced gradually during its recycling and reached to 40.5% at the end of 4th cycle.