Activity of the carbon-based heterogeneous acid catalyst derived from bamboo in esterification of oleic acid with ethanol

Heterogeneous acid catalysts are derived from bamboo through the method of partial carbonization with sulfonation in succession and the catalytic activity is validated through the esterification of oleic acid with ethanol for biodiesel production. Meanwhile, catalysts are characterized by thermogravimetric (TG), nitrogen adsorption, energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and acid-base titration. Under the optimal conditions of carbonization at 350 °C with 2 h duration and sulfonation at 105 °C with 2 h duration, the bamboo derived catalyst possesses amorphous carbon structure with high sulfur content. It shows considerable heat stability below 220 °C and gains the total acid amount of 1.74 mmol g−1. This catalyst could supply the esterification efficiency of 98.4% for acid value reduction with the molar ratio of ethanol to oleic acid of 7, heterogeneous acid addition of 6%, esterification temperature of 90 °C and esterification time of 2 h. In addition, the reused catalyst could be satisfyingly reactivated with the esterification activity of 93.66% under the same esterification condition.