Vetkav R. Parameswaran

N.m.r. analysis of polypropylene-maleic anhydride copolymer

Abstract Polypropylene-maleic anhydride (PP-MA) copolymer was prepared by the solid phase graft copolymerization process. The grafted polymer was analysed by Fourier transform infrared spectroscopy, wet chemical methods, solid state 13 C n.m.r. analysis, and by liquid state 13 C n.m.r. spectroscopy. The solid state, 50 MHz, 13 C n.m.r. showed a distinct peak at 175 ppm indicating the presence of maleic anhydride functionality in the copolymer. These peaks were not detected in the liquid state 13 C n.m.r. spectra due to the presence of dipolar broadening. The structure of the PP-MA copolymer as determined by n.m.r. was in agreement with the proposed structure given by Minoura et al . 1 based on FT i.r. analysis. The extracted solution was analysed by g.c.-m.s. and it was found that unreacted maleic anhydride was extracted by the water. The presence of maleic anhydride in the copolymer was also confirmed by FT i.r.

In-situ reduction of a methanol synthesis catalyst in a three-phase slurry reactor

ABSTRACT In the liquid phase methanol synthesis process, syngas reacts in the presence.of fine catalyst particles slurried in the oil phase, in a three phase slurry reactor system. A method for activating high concentration ( ⩽25 wt. %) of the CuO-ZnO-Al2O3 catalyst in the catalyst-oil slurry has been successfully developed. This catalyst activation process can be of crucial significance in the research and development of the methanol synthesis process in a liquid entrained reactor. The reducing gas contains 2% hydrogen in nitrogen mixture and this activation procedure is carried out at a pressure of 125 psi. The catalyst-oil slurry is subjected to a controlled temperature ramping from 110° to 250° C. The catalyst has beemshown to be effectively reduced after following this activation procedure, that is valid especially for high catalyst loadings in slurry. Since the reduction is carried out in the process liquid medium and inside the reactor system, the catalyst-oil slurry after the treatment is ready fo...

The roles of carbon dioxide in methanol synthesis

ABSTRACT The roles played by carbon dioxide in the chemistry of methanol synthesis over CuO/ZnO/A12O3 catalysts have been experimentally investigated. It was concluded based on reaction rate measurements and thermodynamic considerations, that the two reactions that best describe the chemical system of methanol synthesis are the CO2-hydrogenation and water-gas shift reactions. It was also found experimentally that the presence of CO2 is vital for maintaining the catalytic activity. The significance of the study is enhanced by the fact that this was the first such investigation of the global chemistry of methanol synthesis to be based on the novel liquid phase process. It was also observed that the rates of methanol synthesis attained a maximum when the concentration of carbon dioxide in the reactor feed was controlled at a certain optimal value. The optimal CO2 content was found to be a function of the operating temperature and syngas composition. The experimental data are especially important because the ...

THE ROLE OF WATER IN METHANOL SYNTHESIS

Abstract This work focuses on the influence of water in determining the rate of methanol synthesis over CuO/ZnO/Al2O3 catalysts. The experimental investigations were conducted in a 1-L slurry reactor based on the novel liquid phase methanol synthesis process. The liquid medium used was a blend of paraffinic and naphthenic mineral oils with a mean molecular mass of 250. It was found that the methanol rates attained a maximum at an optimal water content which was dependent on the reaction temperature. The catalytic activity was found to decline with time at lower temperatures in the presence of a relatively large excess of water. The influence of water was also found to be firmly linked to the corresponding carbon dioxide content in the reactor feed. The experimental data bear additional significance because this was the first such study to be performed on the liquid phase process. Emphasis was therefore placed on the use of a CO-rich syngas in order to simulate anticipated process conditions.

MASS TRANSFER IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT The mass transfer characteristics of the liquid phase methanol synthesis process were experimentally investigated using a one-liter, mechanically agitated slurry reactor. The CuO/ZnO/Al2O3 catalyst was crushed to -140 mesh and suspended in an inert mineral oil (Witco # 40). The catalyst loading was varied within limits of experimental feasibility. The effects of temperature, pressure, level of oil, impeller speed, and gas flow rate on the overall gas-liquid mass transfer coefficient KLiaB were studied The results obtained using a two-level, half-fractional factorial design of experiments indicated that the impeller speed, feed flow rate, and temperature had significant effects on the mass transfer coefficient at the experimental conditions examined. Correlations were developed for the Sherwood number based on the Reynolds number, the Schmidt number, the reciprocal gas flow number, the gas-liquid viscosity ratio, and the dimensionless temperature. A simplified power-law type approach was also used...

Supercritical extraction of stuart oil shale

This paper describes the recovery of oil from Stuart oil shale using a supercritical extraction technique employing carbon dioxide as solvent. This supercritical technique provides yields superior to comparable retorting techniques. The importance of extraction temperature, pressure, and time has been investigated. In addition, the chemical composition of the oil extracted from the shale is presented. Simulated distillation has been employed to assess the effect of extraction conditions on the quality of the shale oil extracted.