Cellulose hydrolysis over silica modified with chlorosulphonic acid in one pot synthesis

• Chlorosulfonic acid was immobilized onto silica in simple and direct method using a homogenous rout.
• The FT-IR showed the presence of –SO2– absorption band, while the BET measurements showed the surface area to be 80 m2 g−1.
• The XPS identified O, Si, and S elements in the sample.
• A mixture of DMF/LiCl or cyclohexanol/LiCl has high ability to dissolve cellulose and make the hydrolysis easer.
• A high glucose yield of 99% was achieved over the catalyst with 100% selectivity at 120 °C in 8 h.

Titration of chlorosulphonic acid against sodium silicate was carried out via a simple one pot synthesis at room temperature to form an acid catalyst denoted as RHSO3H. The BET measurements of the catalyst showed the surface area to be 80 m2 g−1. The FT-IR clearly showed the presence of –SO2– absorption band at the expected range. The XPS showed the presence of O, Si, and S. The presence of S 2p on the XPS spectra indicated that the sulphonic acid groups (–SO3H) are included into the catalyst structure. The RHSO3H was efficient for the hydrolysis of cellulose, with maximum glucose yields over 99% at 120 °C with 100% selectivity. As the solubility of cellulose is very important factor to make the hydrolysis much more easily. It was observed that the mixture of DMF/LiCl or cyclohexanol/LiCl has high ability to dissolve cellulose. The catalyst was simple in its preparation, stable during the cellulose hydrolysis in addition to repeatedly without a significant loss of its catalytic activity.

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