Abstract: A carbon-based solid acid catalyst was prepared by a carbonization-sulphonation method from natural biomass wooden powder. The esterification of oleic acid and methanol was taken as the model reaction to investigate the impact of  preparation parameters on the catalyst activity. X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, high-resolution transmission electron microscopy, and elemental analysis were used to characterize the catalyst. The results showed that the carbon-based solid acid catalyst prepared under the optimal conditions of carbonization at 400 ^oC for 0.5 h and then sulphonation at 135 ^oC for 1 h exhibited higher catalytic activity. The conversion of oleic acid reached 96% after reaction for 2 h in an equipment of continuous esterification with a rectifying column for removing water from the system. The biomass carbon-based solid acid catalyst had turbostratic carbon structure, and the sulfuric acid group (–SO₃H) content reached 13.25%. The catalyst showed considerable heat stability below 220 ^oC.

Key words: biomass, biodiesel, carbon-based solid acid, oleic acid, methanol, esterification