Isobaric vapor-liquid equilibrium for methyldichlorosilane- dimethyldichlorosilane-benzene system

The elucidation of vapor-liquid equilibrium (VLE) of the halogenated silane was necessary for the production of silicon derivatives, especially for methylvinyldichlorosilane, due to the lack of the relevant reports. Isobaric VLE for the system methyldichlorosilane-dimethyldichlorosilane-benzene and isobaric VLE of the three binary systems were measured with a new pump-ebulliometer at the pressure of 101.325 kPa. These binary compositions of the equilibrium vapor were calculated according to the Q function of molar excess Gibbs energy by the indirect method and the resulted VLE data agreed well with the thermo-dynamic consistency. Moreover, the experimental data were correlated with the Wilson, NRTL, Margules and van Laar equations by means of the least-squares fit, the acquired optimal interaction parameters were fitted to experimental vapor-liquid equilibrium data for binary systems. The binary parameters of Wilson equation were also used to calculate the bubble point temperature and the vapor phase composition for the ternary mixtures without any additional adjustment. The predicted vapor-liquid equilibrium for the ternary system was in a good agreement with the experimental results. The VLE of binary and multilateral systems provided essential theory for the production of the halogenated silane.

Redistribution Mechanism of Chloromethylsilanes Catalyzed by HZSM-5 with Big and Small Apertures

The disproportionation to produce （CH3）2SiC12 can convert CH3SiC13 and（CH3）3SiCI wastes into treasure. In this paper, B3LYP/6-311＋＋G （3dr, 2pd） basis set was used tocalculate the mechanism of disproportionation, reaction catalyzed by 7T cluster HZSM-5 withsmall aperture and 24T cluster HZSM-5 with large aperture. The results showed that the activationenergies for the rate-determining step of the reaction catalyzed by 7T and 24T HZSM-5 were362.06 and 220.05 kJ/mol, respectively. In combination with the structural analysis, activationenergy analysis and LOL analysis were carried out for 7 T and 24 T HZSM-5. The obtained resultsshow that the 24T HZSM-5 with large aperture is good for disproportionation reaction compared to7T HZSM-5 with small aperture.

HIGH ACTIVITY AND GOOD HYDROGEN RESPONSE SILICA-SUPPORTED ZIEGLER-NATTA CATALYST FOR ETHYLENE POLYMERIZATION

A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane （DMDS） as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalyst exhibited higher catalytic activity, better hydrogen response ability and better copolymerization ability than the commercial M catalyst. Pilot screen in ethylene gas phase fluidized bed polymerization, the catalytic activity of the new catalyst was up to 8000 g PE/g cat, which was twice of that of the commercial M catalyst. The bulk density of polyethylene obtained with the new catalyst was 0.38 g/cm^3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.