Showing papers by "Gongying Wang published in 2007"
TL;DR: In this article, the adsorption of cationic starch on the kaolin surface followed Langmuir isotherm (R2 < 0.98) and showed that increase in flocculant dosage resulted in higher rate constants for the flocculation process and lower rate constant for the aggregate breakage.
105 citations
TL;DR: In this paper, a pure V 2 O 5 catalyst prepared by calcination of NH 4 VO 3 at 550°C in air, was used for the synthesis of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate with phenol.
Abstract: A novel heterogeneous catalyst, pure V 2 O 5 catalyst prepared by calcination of NH 4 VO 3 at 550 °C in air, was used for the synthesis of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol The effects of V 2 O 5 amount, reaction time and molar ratio of dimethyl carbonate to phenol were investigated Under the conditions of mass fraction of catalyst 16%, molar ratio of DMC/phenol of 15:1 and a reaction time 9 h, the maximum conversion of phenol and total yields of methyl phenyl carbonate (MPC) and DPC were 420 and 401%, respectively Reuse of the catalysts revealed an appreciable deactivation X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) characteristics of the fresh and used catalyst samples had been recorded The results showed that the deactivation of the catalyst was mainly ascribed to the conversion of crystal structure Moreover, the deactivated catalyst could be easily reactivated by calcination in air, and the regenerated catalyst showed the catalytic activity almost as high as that of the fresh sample However, a small difference in catalytic activities between regenerated and fresh catalysts was possibly owing to the sintering of the regenerated catalyst
33 citations
TL;DR: In this paper, it was found that titanocene catalysts modified by various substituents would strongly influence the steric and electronic properties of the catalytic centers, the stability of the transition states and their catalytic behaviors.
30 citations
TL;DR: In this paper, various 12-molybdophosphoric salts were used in the transesterification of dimethyl carbonate and phenol to diphenyl carbonate (DPC) and methyl phenyl carbonates (MPC) as novel solid catalysts.
27 citations
TL;DR: In this paper, Cationic starch is found to be an effective flocculant for removal of anionic suspension particles and changes in the electrokinetics of kaolin as a function of pH were investigated.
Abstract: The flocculation characteristics of cationic starches with degree of substitution (DS 0.32–0.63) have been evaluated in 1.0 wt % kaolin suspension by spectrophotometry and colloid titration. Cationic starch is found to be an effective flocculant for removal of anionic suspension particles. Changes in the electrokinetics of kaolin as a function of pH were investigated in the absence of flocculant. The results show that kaolin in water exhibits a negative surface charge at pH > 2.5. The negative hydrophilic surface sites of kaolin are responsible for the adsorption of cationic starch molecules. The experimental data of the adsorption of cationic starch (DS 0.51) follow a Langmuir isotherm with maximum adsorption capacities of 16.89 mg/g. For the adsorption of cationic starch, chemical reaction seems significant in the rate-controlling step and the pseudosecond-order chemical reaction kinetics provides the best correlation for the experimental data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
23 citations
TL;DR: Graft copolymerization of corn starch with acrylamide using ceric ammonium sulphate/citric acid initiation system has been studied under nitrogen atmosphere in aqueous medium.
Abstract: Graft copolymerization of corn starch with acrylamide using ceric ammonium sulphate/citric acid initiation system has been studied under nitrogen atmosphere in aqueous medium. The grafting parameters are favored by increasing monomer concentration and reaction time but are affected by higher concentration of initiator and high temperature. The optimum conditions established for grafting were as follows: the concentration of initiator, 0.003 mol/L; the concentration of citric acid, 0.03 mol/L; monomer/starch, 1:1 feed ratio (w/w); reaction time, 3.0 h; and temperature, 35°C. The extent of grafting was examined by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Both swelling power and solubility increased with the increase in temperature. Graft copolymerization increased swelling power and reduced solubility. Rapid visco-analyzer pasting profile was studied. Graft copolymerization of corn starch results in high pasting temperature, high peak viscosity, and setback as compared with native starch. Breakdown was retarded at low percentage grafting (6.60%) but increased at high percentage grafting (60.27%). POLYM. COMPOS. 28:47–56, 2007. © 2007 Society of Plastics Engineers
16 citations
TL;DR: In this article, Me-HMS was used for the synthesis of diphenyl carbonate by transesterification between dimethyl carbonate (DMC) and phenol.
12 citations
TL;DR: In this article, the V-Cu composite oxide was used for the synthesis of diphenyl carbonate (DPC) by transesterification of dimethyl carbonate with phenol.
9 citations
TL;DR: Stannous-acetylacetonate was used for poly(trimethylene terephthalate) (PTT) synthesis in this paper, where it was shown to be more active and promising than tetrabutyl titanate and stannous octoate for PTT synthesis.
9 citations
TL;DR: In this paper, the coupling reaction of formaldehyde (FA) and methyl formate (MF) to form MG and MG, catalyzed by p -toluenesulfonic acid (p -TsOH) as well as assisted by different kinds of solvents or Ni-containing compounds, was investigated.
5 citations
TL;DR: In this article, the condensation reaction of formaldehyde and methyl formate to form methyl glycolate and methyl methoxy acetate catalyzed by p -toluenesulfonic acid and different Lewis acid compounds has been investigated.
TL;DR: In this paper, the reaction between ethylene carbonate and poly(ethylene terephthalate) was carried out for the simultaneous synthesis of dimethyl carbonate, and the metal acetate catalysts used for this reaction are discussed in detail.
TL;DR: In this article, the transesterification of ethylene carbonate (EC) with dimethyl terephthalate (DMT) was carried out under the following conditions: the reaction temperature 250°C, molar ratio of EC to DMT 3:1, reaction time 3h, and catalyst amount 0.004.