Introducing the sulfone group as a cellulose-binding site to improve the hydrolysis performance of the solid acid

To clarify the role of the specific sulfur-containing functional groups of solid acids in the hydrolysis of cellulose, it is necessary to prepare a solid acid bearing relatively single sulfur-containing functional groups apart from the –SO 3 H group. However, diphenylsulfone cannot be polymerized through Friedel-Crafts alkylation, limiting the possibility of preparing sulfone-based solid acids. Therefore, diphenyl sulfide was crosslinked through Friedel-Crafts alkylation, followed by sulfonation and oxidation. The results showed that the sulfone group was successfully introduced onto the solid acid, and the density of –SO 3 H groups increased by 80.88 % through this strategy. The sulfone group is a strong adsorption site for cellulose, and its introduction leads to a decrease in apparent activation energy. Cellulose conversion and glucose selectivity are as high as 77.54 % and 97.13 %, respectively. Unexpectedly, the stability of the functional groups and carbon skeleton is significantly improved due to the conjugation effect of the sulfone group.