Ning Yin

Synthesis of glycerol carbonate by transesterification of glycerol and dimethyl carbonate over KF/γ-Al2O3 catalyst

A series of KF/γ-Al2O3 solid base catalysts were prepared by a wet impregnation method and applied to the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate. The influences of KF loading and calcination temperature of catalyst on the synthesis were investigated. The results showed that KF/γ-Al2O3 catalysts could promote glycerol conversion to GC efficiently. The structure and properties of the catalysts were studied by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2-adsorption, CO2-temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and Hammett indicator method. It was found that several types of basic centers such as KF, KAlO2, KOH and possibly coordinately unsaturated F- ion existed on the catalysts. The strong basic centers could not only accelerate the conversion of glycerol, but also enhance the formation of glycidol from the decomposition of GC. The recycling of KF/γ-Al2O3 revealed that deactivation of catalyst was strengthened with the reuse times, which was mainly caused by the partial leaching of active potassium species. High calcination temperature favored the transformation of KF to KAlO2 and alleviated the deactivation of the catalyst. Based on the product distribution and obtained results, a possible reaction mechanism on reaction of glycerol with dimethyl carbonate was proposed.

Hydrolytic hydrogenation of cellulose over Ni-WO3/SBA-15 catalysts

Abstract Series of non-precious metal catalysts Ni-WO 3 /SBA-15 were prepared by means of incipient impregnation and applied to the hydrogenolysis of cellulose in aqueous solution. The effect of reaction temperature on the hydrolysis and morphology of cellulose, and the influence of Ni, WO 3 loading on the conversion of cellulose were investigated. High crystalline cellulose was transformed gradually into amorphous state with the increase of reaction temperature. H 2 temperature program reduction of the catalyst proved that a strong interaction existed between nickel and tungsten trioxide, which enhanced the ability of tungsten species to the cleavage of C-C bond and the activity of hydrogenation of nickel. Thus, the transformation of cellulose into ethylene glycol was strengthened markedly. The complete conversion of cellulose and 70.7% ethylene glycol yield were obtained over a 3% Ni-15% WO 3 /SBA-15 catalyst under the reaction condition of 230°C and 6.0 MPa H 2 for 6.0 h.

Preparation and properties of rigid polyurethane foam based on modified castor oil

Castor oil polyol (COP) having a hydroxyl number of 400 mg KOH/g was prepared through the transesterification reaction of castor oil with glycerol. The effect of reaction temperature on the composition, hydroxyl number and viscosity of the COP products was studied. A series of rigid polyurethane foams were synthesised using the mixtures comprising COP and a petroleum-based polyol with various proportions as polyol component. It was found that the foaming rate, compressive strength and dimensional stability and morphology of resulting foams were dominated by the foam formulation, in a more accurate way, COP content in the polyol mixtures. The combination of expandable graphite and dimethyl methyl phosphonate exhibited stronger flame retardant function which was ascribed to the synergistic effect associated with the simultaneous presence of the two additives. An improvement in thermal stability was observed due to the inclusion of the flame retardants.