Transcripción del resumen del autor. Heterogeneous catalysts bearing sulfonic acid groups were prepared using biochar as the carbon support. Biochar samples were first treated with KOH before carbonization at different temperatures (450, 675, and 875 °C) then sulfonated using fuming H2SO4 at 150 °C for 15 h. The sulfonated catalysts were characterized using BET surface area and porosity, elemental analysis, total acid density, FT-IR spectroscopy, X-ray diffraction, and thermogravimetric analysis. Catalytic performance was determined via the transesterification of canola oil with methanol. The reaction yield was found to be dependent on both catalyst surface area and total acid density, suggesting that the maximum yield would be obtained for a catalyst prepared from char carbonized between 675 and 875 °C. FT-IR spectra and XRD patterns reveal that higher carbonization temperatures cause an increasing reorientation of the biochar’s carbon sheets toward a more graphite-like structure, decreasing the total acid density despite the increasing surface area. Catalyst reusability was poor under high temperature/pressure conditions.

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