Pyrolysis and modification of coconut shell into sulfonated biochar and its catalytic activity on cellobiose conversion

Coconut shell was successfully valorized into sulfonated biochar through carbonization in various temperatures and duration. This work aims to provide suitable solid acid carbonaceous catalyst for cellobiose conversion into valuable product. Sulfonated biochar is characterized to evaluate its crystallinity, sulfonate, and oxygenated functional groups by XRD method and FTIR spectroscopy. The resulting solid acid carbonaceous material was tested toward cellobiose hydrolysis to assess its catalytic activity in various time, temperature, and catalyst weight. FTIR spectra reveals some of the biochar product has sulfonate group as indicated by absorbance band at 1234 cm‒1, 1070 cm‒1 and 1180 cm‒1, which belongs to -SO3H and O=S=O vibration. The most noticeable spectra are found on biochar prepared at 800℃ in 1.5 h to 2 h carbonization. Diffraction pattern shows similar peak that characteristic of biochar at 2θ 23 and 44°. Long duration process and higher temperature of carbonization affects the product to becomes less crystalline and smaller amplitude. Catalytic activity of sulfonated biochar toward cellobiose hydrolysis shows mixed result of total reducing sugar yield. Overall, sulfonated biochar able to hydrolyze cellobiose at optimum condition 12 h and 150℃ resulting in total reducing sugar by 178 ppm.