Upgrading catalytic efficiency of activated carbons by tailoring lignocellulosic biomass waste for sustainable conversion of glycerol to solketal

Abstract

This study introduces a novel strategy for boosting both surface acidic properties and textural features of a series of activated carbons from petiole of Mauritia flexuosa Linnaeus fillius, a lignocellulosic biomass waste. The structure, state and concentration of lignin, cellulose and hemicellulose into the selected precursor underwent a reconfiguration protocol aiming at tunning surface features of the carbons-based catalyst chemically activated with H3PO4. In fact, the modified precursors gave rise to activated carbons that boast surface area of up to 2349 m2.g−1 and total acidity ranging from 2.22 to 3.13 mmol.g−1, making them suitable candidate to promote the conversion of glycerol to solketal. The catalysts were successfully applied in the solvent-free acetalization of glycerol with acetone achieving glycerol conversion higher than 83% (selectivity around 98% toward solketal) with remarkable turnover frequencies as well as a notable reusability in consecutive runs. Further, it was noticed that the diversity of acid strength of the reactive sites played an important role in each step of the reaction mechanism synergically improving catalytic performance. The physicochemical and surface chemistry properties of the activated carbons were characterized by means of N2 adsorption/desorption isotherms, thermal analysis, elemental analysis, surface functional groups titration, X-rays diffraction, scanning electron microscopy and FTIR spectroscopy.