Catalytic Production Of Reducing Sugar From Bio-cellulosic Materials Over Acidic Clay Catalysts

Cellulose is an abundant biomass resource which can be considered as one of the most attractive alternatives to replace fossil resources.However,the hydrolysis of cellulosic materials to useful products seems far from being satisfactory,because cellulose is the most difficult hydrolysis material in biomass.In the traditional process,liquid acid,alkali or enzyme were used as catalyst to conversion cellulose to glucose,and then further convert to energy or other fine chemicals further.The long,irreversible route leads to the recovery of waste acid,processing,and certain environmental pollution.Therefore,we use relatively more green solid catalyst to catalytic conversion of cellulose.The preparation of the solid catalyst is simple,while the catalysts have good thermal stability,easy separation and non-corrosive,etc.,so the replacement of liquid catalyst with the solid catalyst will be friendly to the environment.So far,the montmorillonite catalysts have not been reported on conversion of cellulose,also conversion of cellulose at low temperatures is still a challenge.The structures of the acid treated montmorillonite,microcrystalline cellulose and bamboo materials were characterized by using modern physical and chemical techniques,such as X-ray diffraction(XRD),fourier transformation infra-red spectra(FT-IR),scanning electron micrograph(SEM)and thermogravimetry-differential thermal analyzer(TG/DTA).For the system of catalytic conversion of microcrystalline cellulose,the montmorillonite-based catalysts have better catalytic properties than others.Furthermore,the catalytic properties montmorillonite can be greatly improved after acid-treated.The catalytic activity of inorganic acid-treated montmorillonite is higher than the organic acid-treated montmorillonite.Generally,when using H2SO4/MMT as catalyst,conversion of cellulose is higher than H3PO4/MMT and PTSA/MMT,and the maximum conversion can be achieved as up to 91.15 wt%when using 20%H2S04/MMT as a catalyst.While for the yield of reducing sugar,using H3PO4/MMT as catalyst was higher than H2SO4/MMT and PTSA/MMT,and the maximum yield was up to 16.94 wt%when using 10%H3PO4/MMT as a catalyst,which indicates that H3PO4/MMT had the best catalytic activity in the conversion of cellulose to reducing sugar.For the catalytic conversion of bamboo system,when using PTSA/MMT as catalyst,conversion of bamboo is higher than H2SO4/MMT and H3PO4/MMT,and the maximum yield of reducing sugar was up to 8.08 wt%when using 10%PTSA/MMT as a catalyst.No matter using which kinds of acid-treated montmorillonite,conversion of bamboo was not changed much,all in the range of 64-72 wt%.However,after bacterial treatment,the conversion of bamboo changed greatly,and the range was expanded from 50 wt%to 90 wt%.Compared with the before bacteria-treated bamboo,the conversion of bamboo was slightly increased.The highest conversion of bamboo was 89.84 wt%when using 20%H2SO4/MMT as catalyst,and the highest yield of reducing sugar was 8.75 wt%when using 20%PTSA/MMT as catalyst.The typical diffraction peaks of cellulose were found in the X-ray powder diffraction patterns of bamboo samples.After reaction 4 hours at 473 K,the bamboo was completely destroyed.