Maoqing Kang

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.

Catalytic conversion of glucose and cellobiose to ethylene glycol over Ni–WO3/SBA-15 catalysts

Hydrogenolysis of glucose and cellobiose, used as the model feedstocks, over Ni–WO3/SBA-15 catalysts has been investigated to probe the influencing factors for the conversion of cellulose to ethylene glycol (EG). The conversion of glucose and cellobiose to EG showed different dependencies on reaction temperature; a lower reaction temperature was needed for the former. Additionally, the surface atomic ratio of W to Ni on the Ni–WO3/SBA-15 catalysts was the key factor for the product distribution. Both glucose and cellobiose had their own optimum W–Ni ratio for the production of EG, and the ratio of W to Ni for glucose was slightly lower than that of cellobiose. On the other hand, the Ni–WO3/SBA-15 catalysts were thoroughly characterized by N2 adsorption–desorption, X-ray diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results indicated that the reducibility of Ni–WO3/SBA-15 catalysts with high Ni loading was more similar to that of pure NiO. More importantly, the change of surface atomic content of Ni and W of Ni–WO3 catalysts with various Ni loadings resulted from the surface W species of the catalysts being gradually covered by Ni species with the increase of Ni loading.

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.

A Novel Non-phosgene Approach to the Synthesis of Methyl N-phenyl Carbamate by a Reaction of Methanol with Phenylurea

A novel non-phosgene process for the synthesis of methyl N-phenyl carbamate (MPC) by a reaction of phenylurea with methanol was studied. The reaction between phenylurea and methanol was found to be a spontaneous reaction that took place in the absence of catalyst and gave MPC as the main product. Addition of a catalyst markedly influenced the reaction behavior. A basic catalyst greatly enhanced the yield of MPC, whereas an acidic catalyst promoted the formation of aniline and methyl carbamate. Moderate strength of basicity showed the best catalytic performance in the cases studied. The mechanism of reaction and catalyst functioning was discussed.

Catalytic conversion of glucose and cellobiose into ethylene glycol over various tungsten-based catalysts

Abstract Glucose and cellobiose were used as model compounds to investigate the effect of retro-aldol condensation and hydrogenation rates on the product distribution of cellulose conversion. It was shown that the product distribution obtained over the physical mixture of Ni/SBA-15 and WO 3 /SBA-15 in the glucose and cellobiose conversions were different from that attained on the Ni-WO 3 /SBA-15 prepared by the co-impregnation method. The ethylene glycol (EG) yield depended on the structures of tungstic compounds, and it increased in the order of WO 3 3 /SBA-15 4 ) 6 W 7 O 24 ·6H 2 O (AMT), while the particle sizes of them decreased in such an order. Regardless of the types of tungstic compounds, the EG yield obtained in the glucose conversion is lower than that attained in the cellobiose conversion at the same amount of catalyst.

Synthesis of a novel CO2-based alcohol amine compound and its usage in obtaining a water- and solvent-resistant coating

A five-membered cyclo-carbonate, prepared by cycloaddition reaction from CO2 and 1,4-butanediol diglycidyl ether, was reacted with excessive diamine and formed a urethane group-containing new product. Structural characterization was performed for the new alcohol amine, which can be applied to the manufacture of polyurethane coatings as a chain extender. The new chain extender-based polyurethane coatings exhibited excellent water, salt, and solvent resistance and promising mechanical strength. Importantly, the unique performance of the prepared polyurethane coatings should be ascribed to the introduction of a hydroxyl group in the polyurethane molecule. The strengthened hydrogen bonding enlarged the cohesion of the polyurethane coatings and prohibited the solvents from permeating.

Supported ZnBr2 and carbon nitride bifunctional complex catalysts for the efficient cycloaddition of CO2 with diglycidyl ethers

The cycloaddition reaction of carbon dioxide (CO2) and bisepoxides is an interesting route for CO2 utilization and green non-isocyanate polyurethane (NIPU) synthesis. In this work, a series of γ-Al2O3 supported ZnBr2 and carbon nitride complex catalysts (Zn–CN/γ-Al2O3) were prepared by a simple thermal polymerization method and applied to the cycloaddition reaction. The results showed that 0.05Zn–CN/γ-Al2O3 exhibited high catalytic activity, over which 91.4% 1,4-butanediol diglycidyl ether (BDODGE) conversion and 98.9% cyclic carbonate selectivity were acquired under solvent and co-catalyst free conditions. The relationship between the structural properties and catalytic performance of Zn–CN/γ-Al2O3 catalysts was studied in detail. It is found that the high surface area and the synergistic effect of Lewis acid–base duality are key factors for the high activity of catalysts. Introducing ZnBr2 could provide acid sites and induce structure change of carbon nitride, which could determine the basic intensity of catalysts. Moreover, based on the elaborate discussions, a plausible catalytic reaction mechanism was proposed.