Regulation of oxygen-containing functional groups of dual acid core-shell carbon-based catalysts and induction of xylose hydrothermal conversion

A core-shell carbon-based catalyst mZSM-5@SO42-/mC-1.5N with mZSM-5 as core and SO42-/mC-1.5 N as shell was prepared using phenolic resin as carbon source. The conversion of xylose was 97.4% and the furfural yield was 75.4% at 140 ℃ for 1 h when the catalyst was used to the reaction of xylose to furfural. The high activity of mZSM-5@SO42-/mC-1.5 N was attributed to the core-shell structure could construct a high activity Brønsted acid-Lewis acid (BA-LA) interface, which promoted the synergistic effect of LA and BA and was conducive to the xylose-furfural cascade reaction. In additon, the combination of HNO3 activation and H2SO4 grafting method adjusted the density of -OH, -COOH and -SO3H on the mC surface, improved the Brønsted/Lewis (B/L) and hydrophilicity of the catalyst, and promoted the adsorption, fixation and transformation of xylose. Then, the effect -OH, -COOH and -SO3H in the reaction of xylose-furfural was studied by characterization analysis. Finally, the experimental results showed that mZSM-5@SO42-/mC-1.5 N could reduce the activation energy of the xylose-furfural reaction, and the catalyst could maintain good stability after recycling and regeneration.