Modulation of sulfur-containing groups in the carbon skeleton of solid acids by liquid sulfur carbonization to promote cellulose hydrolysis

Abstract

Improving carbon skeleton structure of solid acids is essential to enhance their hydrolysis activity. In this work, sulfur-modified solid acid was prepared by liquid sulfur carbonization for the hydrolysis of cellulose. The liquid sulfur environment makes the cellulose adequate contact with sulfur during the carbonization process, which is beneficial for the entry of sulfur into the carbon skeleton. Sulfur is doped into the solid acids in various forms and the forms and content of sulfur-containing groups in the solid acids were successfully regulated by adjusting the ratio of cellulose to sulfur. As the ratio of cellulose to sulfur increases, the different sulfur-containing groups show regular changes, influencing hydrolysis activity. Because of hydrogen bonding between SO and cellulose, SO3H group is more accessible to the cellulose which leads to a significant increase in the hydrolysis activity of the solid acid.