Solid Urea Sulfate Catalyst for Hydrolysis of Cellulose

Abstract

A new treatment has been demonstrated for urea to synthesis solid-state form of urea sulfate onto silica extracted from rice husk ash via 3-(chloropropyl)triethoxysiline. The 3-(chloropropyl)triethoxysilane was immobilized onto silica at room temperature to functionalize the silica with chloride end groups. The chloride groups were reacted with urea by a nucleophilic substitution reaction. The resulting silica with urea (which had amine end groups) was sulfated with diluted sulfuric acid to produce a novel solid state form catalyst designated RHAUR-SO4H (RHA = rice husk ash). The XPS, EDX and CHNS analysis show that the expected elements were presents in RHAUR-SO4H. The FT-IR spectrum showed the presence of absorption bands attributed to the +NH3 and O=S=O ions groups which confirmed the results were coming from elemental analysis. The TGA\DSC analysis shows that the catalyst is stable at temperatures below 185 °C. Cellulose was hydrolyzed to glucose over RHAUR-SO4H in 2 h, and the glucose was hydrolyzed afterwards to other products within 7 h using a mixture of cyclohexanol\LiCl as a novel solvent system. The catalyst is reusable without a significant loss of catalytic activity.