Arylsulfonic acid functionalized hollow mesoporous carbon spheres for efficient conversion of levulinic acid or furfuryl alcohol to ethyl levulinate

• ArSO3H-based hollow mesoporous carbon spheres ArSO3H-HMCSs are prepared.
• ArSO3H-HMCSs exhibit excellent catalytic activity in synthesis of ethyl levulinate.
• Hollow mesoporous spherical morphologies positively influence the catalytic activity.
• ArSO3H-HMCSs can be reused at least 10 times without loss of catalytic activity.

A series of arylsulfonic acid functionalized hollow mesoporous carbon spheres (ArSO3H-HMCSs) with controllable ArSO3H loadings (1.8 and 3.2 wt%) and inner diameters (120–260 nm) were successfully prepared by chemical bonding ArSO3H groups to furfuryl alcohol-derived hollow mesoporous carbon spheres via diazonium coupling. The morphology, textural properties and chemical structure of as-prepared ArSO3H-HMCSs were well characterized by TEM, FESEM, nitrogen gas porosimetry measurement, XRD measurement, Raman scattering and FT-IR spectroscopy as well as XPS surface probe technique. As the novel solid acid catalysts, the catalytic activity and stability of the ArSO3H-HMCSs were evaluated by synthesis of ethyl levulinate from biomass-derived platform molecules, levulinic acid or furfuryl alcohol. The obtained excellent acid catalytic activity in comparison of other carbon-based SO3H catalysts such as ArSO3H-functionalized ordered mesoporous carbon, sulfonated hollow mesoporous carbon spheres as well as sulfonated incompletely carbonized d-glucose and cellulose was explained in terms of their strong Brønsted acidity and perfect hollow nanospherical morphology with thin mesoporous shell.

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