Simultaneous carbonization and sulfonation of microcrystalline cellulose to obtain solid acid catalyst and carbon quantum dots
2022
Souza, M.C.G. | Batista, A.C.F. | Cuevas, R.F. | da Silva Filho, W.J.F. | Balanta, M.A.G. | Champi, A. | de Assunção, R.M.N.
Lignocellulosic materials have been successfully used in the production of solid acid catalysts (SACs), generally prepared in two steps: Biomass thermal or hydrothermal carbonization followed by sulfonation. The process' supernatant is usually discarded; however, this liquid fraction may contain potentially important substances. In this work, the production of SACs was carried out by simultaneous carbonization/sulfonation of Microcrystalline Cellulose (MCC) by direct reaction with concentrated sulfuric acid. The obtained catalyst have excellent characteristics, with an ionic exchange capacity of 1.3 mmol g⁻¹. The SAC's catalytic activity was evaluated in oleic acid esterification with methanol in a molar ratio of 1:20, yielding up to 80 % conversion in 6 h of reaction at 65 °C. The supernatant showed the presence of carbon dots (CD) characterized by solution UV/Vis spectra pattern and Fluorimetry assays. Thus, the presented process allows obtaining SACs and CDs that can act as catalysts in a series of physicochemical processes.
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