Solid Acid Catalyst Derived from Cotton for Conversion of Xylose and Corn Cob to Furfural

Carbon-based solid acid catalysts (CS-SO3H) were prepared by one-pot carbonization-sulfonation method with concentrated sulfuric acid using cotton as raw material, which was used to transformation of xylose and corn cob to furfural. The catalyst preparation conditions were optimized to be that the cotton mass/sulfuric acid volume ratio is 1 : 20 (g/mL), and the reaction is carried out at 160 degrees C for 10 h. The morphology, functional groups and surface chemical state were investigated. The yield of furfural can reach 87.3 % from xylose under the optimal reaction condition of 0.1 g xylose, 0.05 g catalyst, 180 degrees C for 90 min in 5.0 mL gamma-valerolactone-water solvent. The yield of furfural can reach 63.2 % by the direct one-pot conversion of corn cob over the CS-SO3H under the optimal reaction condition of 0.1 g corn cob, 0.1 g catalyst, 190 degrees C for 90 min in 5.0 mL gamma-valerolactone-water solvent. The catalytic activity gradually declined when it was cycled for four times. The reason was determined to be the partial shedding of the sulfonic acid groups grafted on the catalyst during the reaction and insoluble humus accumulated on the catalyst surface. After regeneration, the catalytic activity can be restored.