Study On Cellulose Hydrolysis Using Carbon-based Solid Acid Catalyst

At present, the production and life of human are mainly based on fossil fuels. With energy crisis and series of pollution problems highlighting, people force to develop and make use of clean renewable energy. Biomass, the fourth largest energy source, attract concerns all over the word. Biomass providest an important choice to prepare the platform compounds by chemical conversion of biomass. Cellulose derived platform compounds are value added. Cellulose saccharification is the main approach toobtaining the important monosaccharide glucose. Generally the liquid acid catalyst is used for hydrolysis of cellulose. However, liquid acid bring the potencail environmental pollution, equipment corrosion and separation problems. More and more sreearch group resor to the solid acid. Currently H-type zeolite, cation-exchange resins, transition metal oxides, heteropoly acids are employed por cellulose hydrolysis. Some obstacles influce the large scale utilization of these catalyst, such as low catalytic efficiency, poor thermal stability and low recovery. Therefore, the study of novel solid acids catalyzed hydrolysis of cellulose has an important significance.Activated carbon and multi-walled carbon nanotubes as raw materials, carbon-based solid acid catalyst was prepared by charring sulfonation methods. To characterize the morphology of the catalyst and discuss the glucose yield of microcrystalline cellulose hydrolysis with catalytic at the different conditions for optimum hydrolysis conditions.Activated carbon-based solid acid is prepared with activated carbon by heating for 6 hours at 150 ℃ concentrated sulfuric acid. The optimum glucose yields of 17.52% was obtained in catalyzed hydrolysis of cellulose experiment(120℃,3 hours, catalyst dosage 0.15 g). The optimum yields of cellulose glucose was 14.78%by carbon nanotube-based solid acid (120℃,3 hours, catalyst dosage 0.15 g), which was obtained via multi-walled carbon nanotubes sulfonation by concentrated sulfuric acid at 150℃ for 6 hours. The two catalysts are amorphous structure containing sulfonic acid groups, carboxyl groups and hydroxyl groups. Activated carbon-based solid acid and carbon nanotube-based solid acid catalyst to optimize the transformation were coated with a glucose solution of activated carbon and carbon nanotubes, and then pyrolysis carbonization at 400 ℃, and then sulfonated in concentrated sulfuric acid, prepared deposited in situ of activated carbon solid acid and deposition in situ of carbon nanotubes solid acid.After optimization of the hydrolysis conditions, highest glucose yield of 29.12% was obtained by deposition in situ of carbon nanotubes solid acid at a temperature of 120 "C, for 3 hours time, catalyst dosage 0.15 g, much higher than the best deposition in situ of activated carbon solid acid production rate of 16.74%.In order to better separation and recovery of deposition in situ of carbon nanotubes solid acid, it is filled Fe3O4 magnetic particles in its interior to prepare magnetic deposition in situ solid acid. The catalysts were characterized by X-ray diffraction, physical adsorption, X-ray photoelectron spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy and Raman spectroscopy. The evidence that the catalyst with high specific surface area is deposited by amorphous polycyclic aromatic carbon layers polycyclic aromatic, having Fe3O4 nanoparticles, introducing sulfonic acid groups, carboxyl groups and hydroxyl groups. The optimal glucose yield of cellulose hydrolyzing is 28.38% with 0.15 g catalyst at 120℃ for 3 hours. Reuse of solid acid properties were studied. The basic stability of the catalytic efficiency is around 28% at the first five use times. The catalyst from the first use to be reused seven times, glucose yield decreased from 28.38% to 24.56%, indicating that the catalyst has good re-use performance.The environment friendly carbon-based solid acid catalyst exhibits the high catalytic activity, thermal stability, good reusing properties. Tt is the most promising "green catalyst" and likely to play an important role in terms of catalytic cellulose hydrolyzing.