(176e) Sulfonated Coconut Shell Biochar As an Acid Catalyst for the Hydrolysis of Waste Cellulosic Biomass

The valorization of coconut-shell waste by converting it to acid catalyst particles can circumvent the need for its disposal by CO₂-generating combustion. In this paper, the physicochemical characteristics of sulfonic acid functionalized biochar, derived by the carbonization of coconut shell, will be discussed and correlated to its catalytic activity. Coconut shell biochar was obtained by carbonization at temperatures in the range of 400 to 700 °C and sulfonated by treatment with concentrated sulfuric acid. The BET surface area of the biochar was ~400 m² g^-1 but decreased about a hundred-fold after sulfonation. The total acid density, determined by the Boehm titration method, increased with the carbonization temperature. The sulfonic acid density was also separately quantified. Since a relative excess of concentrated sulfuric acid (5 to 50 mL/g-biochar) was used in the sulfonation step, the sulfonic acid density of the biochar would be expected to be independent of the sulfuric acid amount. However, interestingly, it decreased with the amount of sulfuric acid. The biochar solid acid catalyst was used to hydrolyze corncob, and the reducing sugar concentration in the hydrolysate was measured. The sugar yield increased with the sulfonic acid density of the catalyst particles.

Reference:

Igboke, O. J.; Orimolade, T.; Prevatt, G. H.; Odejobi, O. J.; Krishnan, S. Composition and Morphological Characteristics of Sulfonated Coconut Shell Biochar and its Use for Corncob Hydrolysis. Waste and Biomass Valorization 2023. https://doi.org/10.1007/s12649-023-02080-0