Design And Synthesis Solid Catalyst To Apply In Hydrolysis Of Cellulose To Glucose

Cellulose as a main kind of polysaccharide, is widely in nature. The moleculer ofcellulose is connected by β-1,4glucosidic with many glucose units. In water ororganic solvent, cellulose can be hydrolyzed into fuel and chemicals, such as glucose,5-HMF and levulinic acid et al. But as the special structure of cellulose, the aboveprocesses are different to perform, and needed for the help of catalyst. There are manydisadvantages for the traditional enzyme hydrolysis and chemical hydrolysis, forexample the long reaction time, corrosion for the equipments and enviromentalpollution. So the efficient, green and economic catalyst is needed for the economicand social value.Heteropolyacids are a kind of solid acid, which have the strong Br nsted acidity（B-acid） and can be dissolved in water. When the hydrogen ion is replaced bydifferent cations, there will be many new catalysts. These new catalysts not onlycontain the Br nsted acidity, but also the character of cations.As the above reasons, we want to find some efficient and green catalysts for theconversion of polysaccharide under mild conditions. The main results of our paper areas follows:1. Part of hydrogen ions of12-tungsten phosphoric acid (H₃PW₁₂O₄₀) arereplaced by hexadecyl trimethyl ammonium Bromide [CH₃（CH₂）₁₅N（CH₃）₃Br] toform the micelle catalyst of B-acid [CH₃（CH₂）₁₅N（CH₃）₃]H₂PW₁₂O₄₀, which have theboth characters of B-acid and surfactant. It was characterized by using infraredspectra （IR）, elemental analysis,31P （NMR） and transmission electron micrograph（TEM）.（1）(C₁₆TA)H₂PW₁₂O₄₀as a solid acid catalyst was used for the hydrolysis ofsucrose. The reaction conditions: a mixture of sucrose （1.6g） and catalyst （0.263g） indistilled water （8mL） were heated at80°C in a steal autoclave lined with Teflonunder air for1h with agitation. The conversion of sucrose and the selectivity ofmonosaccharide are100%and99.6%, respectively. The reaction mixture wascentrifuged to separate the catalyst from the products after the reaction. And thecatalyst can be resued after washing the impurities and drying.（2）(C₁₆TA)H₂PW₁₂O₄₀as the solid acid catalyst was used for the hydrolysis ofstarch. The result shows that: a mixture of starch （0.1g） and catalyst （0.07mmol） in7 mL water were heated at120oC for5h with agitation. The conversion of starch andthe selectivity of glucose are96.1%and85.7%, respectively.（3）(C₁₆TA)H₂PW₁₂O₄₀as the solid acid catalyst was used for the hydrolysis ofcellulose. The result shows that: a mixture of cellulose （0.1g） and catalyst （0.07mmol） in distilled water （7mL） were heated at170°C in a steal autoclave lined withTeflon under air for8h with agitation. The yield of total reducing sugar （TRS） andglucose are39.9%and38.3%, respectively. The reaction mixture was centrifuged toseparate the unreacted cellulose and catalyst after the reaction. Continue the abovereaction, the yield of TRS and glucose are38.6%and37.7%，respectively. And thethird reaction, TRS and glucose are9.0%and8.7%. Result shows that this catalystcab be reused.2. C₇H₁₂N₂SO₃H（MIMPS）replaced some hydrogen ions of H₃PW₁₂O₄₀to formthe B-acid catalyst [MIMPS]H₂PW₁₂O₄₀, which contained the imidazolyl cation. Itwas characterized by using infrared spectra （IR）,1H nuclear magnetic resonance（NMR）.[MIMPS]H₂PW₁₂O₄₀was used for the hydrolysis of cellulose. The resultshows that: a mixture of cellulose （0.1g） and catalyst （0.07mmol） in0.5mL waterwith5mL MIBK were heated at140oC for5h with agitation. The conversion ofcellulose and the yield of glucose are55.1%and36.0%, respectively.