Synthesis Of Tungsten Based Nanomaterials And Its Application In Catalytic Hydrogenation Of Cellulose

Energy and environmental crisis threaten human survival in the modern society. Cellulose is the most abundant and renewable biomass in nature, which is a linear polymer of D-glucose with β-1,4-glycosidic bonds. Catalytic conversion of cellulose to fine chemicals by tungsten based nanomaterials has great significance for the world to solve the energy crisis. Moreover, the photocatalytic properties of tungsten based nanomaterials can be improved by decoration. Therefore, it can be applied to solve water pollution.MCM-41 supported Ru, Pt, Pd, Rh and WO3 with different weight loadings were prepared by incipient impregnation and applied to the hydrogenalysis of cellulose. The effects of reaction temperature, time, pressure of H2, the influence of Ru, WO3 loading and kind of noble metal on the conversion of cellulose have been investigated. The tungsten species can promote the selective cleavage of the C-C bonds in the sugar intermediates, thus leading to the preferential formation of ethylene glycol.The results show that Ru, Pt, Pd, Rh and WO3 are deposited inside the mesochannels and are well dispersed on the surface of the hexagonally ordered mesoporous MCM-41 support. The selective of ethylene glycol is the best when Ru-WO3/MCM-41 is selected as the catalyst in the hydrogenalysis of celluose. The conversion of cellulose and maximum yield of ethylene glycol were 90.6% and 55.6%, respectively, at optimal reaction condition of 240℃ and 4.0 MPa H2 for 0.5h with 2%Ru-15%WO3/MCM-41 catalyst.In addition, a series of Mo-doped WO3 rectangular nanosheets are synthesized for the first time through a hydrothermal synthetic method. The effect of doping Mo and the photocatalytic mechanism have been investigated by degradation of RhB organic dyes under visible-light irradiation. The results show that a homogeneous distribution of Mo in the as-prepared samples. The photodegradation of RhB over pure WO3 is merely 59.2% after 3 h of visible light irradiation at pH 12, while the degradation rate will reach a peak value 92.0% at the doping amount of 1% Mo. This improvement relied on the synergy of the well narrowed band gap of WO3, which decline from 2.60eV to 2.51eV, and facilitated separation of the photo-excited electrons and holes, both of which were created by Mo doping.