Formation of hydroxyl-rich carbon layer coated silica microspheres and its application to enhance hydrolysis of cellulose to sugar

The formation of hydroxyl-rich carbon layer coated silica microspheres (SiO 2 –NH 2 @C) under hydrothermal carbonization (HTC) conditions is demonstrated for the catalytic hydrolysis of regenerated cellulose to sugar. The driving factors for the formation of the SiO 2 –NH 2 @C and the different morphologies are investigated through the surface amino modification of silica and the control of the carbon source concentration during the HTC cladding process . The surface silica atom content after hydrothermal treatment of unmodified and modified silica is 14.24% versus 1.17% respectively. This shows the introduction of amino groups can drive the formation of the carbon layer coated structure through electrostatic interactions . As can be seen from the SEM and TEM images, 2 nd HTC and adjustment of the concentration of the carbon source can control the morphology of the SiO 2 –NH 2 @C. With the strong adsorption between the hydroxyl-rich hydrothermal carbon outer layer and the cellulose, it is possible to hydrolyze 96.4% of the regenerated cellulose to glucose under pure aqueous phase ultra-dilute acid conditions, with a glucose yield of 75.8%. A clearer understanding of the driving factors and control conditions for the formation of the hydroxyl-rich SiO 2 –NH 2 @C structure is provided, along with a more definite direction for the preparation of similar nanomaterials .