Molar Ratio Of Dimethyl Carbonate Research Articles

Coupling reaction and azeotropic distillation for the synthesis of glycerol carbonate from glycerol and dimethyl carbonate

A new process, coupling reaction and azeotropic distillation was proposed for the synthesis of glycerol carbonate (GC) from glycerol (G) and dimethyl carbonate (DMC). The bench scale experimental investigation was systematically conducted for this new process. With calcium oxide (CaO) as the solid catalyst, the high yield of glycerol carbonate can be obtained at a low molar ratio of dimethyl carbonate to glycerol with the method of coupling reaction and azetropic distillation. The effect of azeotropic agents on glycerol carbonate yield was explored, and indicated that benzene was the most effective azeotropic agent. The effects of the process parameters, tower height, amount of added benzene, final temperature of tower bottom and reflux ratio were investigated. Glycerol carbonate yield can be as high as 98% under the conditions at molar ratio of dimethyl carbonate to glycerol 1:1, final temperature of tower bottom 85 °C, 1.5 mass ratio of added benzene to that in the azeotrope with methanol theoretically produced and reflux ratio 4. By continuously removing methanol from reaction system with the method of coupling reaction and azeotropic distillation, the yield of glycerol carbonate can be retained at high level using the recycled catalyst.

Transesterification of dimethyl carbonate with phenol to diphenyl carbonate over V 2O 5 catalyst

A novel heterogeneous catalyst, pure V 2O 5 catalyst prepared by calcination of NH 4VO 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 2O 5 amount, reaction time and molar ratio of dimethyl carbonate to phenol were investigated. Under the conditions of mass fraction of catalyst 1.6%, molar ratio of DMC/phenol of 1.5:1 and a reaction time 9 h, the maximum conversion of phenol and total yields of methyl phenyl carbonate (MPC) and DPC were 42.0 and 40.1%, 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.