Mass transfer and solubility in autocatalytic oxidation of cyclohexane

Abstract

Mass transfer coefficients for the solution, without reaction, of oxygen in cyclohexane over a wide range of temperature and pressure have been measured in a flat interface reactor (FIR) and a gas sparged stirred-tank reactor (STR). Solubilities have also been measured and it is suggested that a modified Henry's law coefficient of 1.09 x lo-' kmol/m3 . bar can be regarded as constant over the temperature range 293-435 K. The physical mass transfer coefficient in the STR shows very little variation over this temperature range and a value of 3.5 x m / s can be assumed for 423-435 K. However, coefficients in the FIR increase with agitation rate as expected. The difference is ascribed to interference by neighboring bubbles in the transfer process, when diffusivities are high, and also to the lowering of surface tension at high temperatures. A model proposed by Gal-Or and Resnick is reviewed in its application to the present system.

Catalytic Properties of Alumina-Supported Ruthenium, Platinum, and Cobalt Nanoparticles towards the Oxidation of Cyclohexane to Cyclohexanol and Cyclohexanone

“…These results show that when the temperature increased from 25 to 70 °C, the conversion and selectivity towards cyclohexanone and cyclohexanol increased and The second order plots gave a straight line, indicating that the reaction is of the 2 nd order, as shown in Figure 6. The activation energy, calculated from the slope of the straight line (Figure 6), is 31.23 kJ mol -1 , which is lower than the values reported in several previous works [42][43][44][45][46][47]. The effect of the mole ratio was examined by varying the cyclohexane/TBHP mole ratios (1:1 and 1:2), with 0.05 g of Ru/Al2O3 catalyst at 70 °C, for 6 h (Figure 7).…”

Autocatalytic oxidation of cyclohexane—modeling reaction kinetics

“…The mass transfer coefficients shown in the figures are the values obtained from the data in the slow reaction regime (Suresh et al, 1987). The reaction rates are seen to correlate very well with conversion at a given temperature in the initial part of the experiments.…”

Photo-catalytic oxidation of cyclohexane over TiO2: a novel interpretation of temperature dependent performance

“…The intensity of the absorption band of adsorbed hexanoic acid was compared to that of adsorbed cyclohexanone (not shown) and the first was around two times larger than the second, so the calibration factor of carboxylates was set at two times the value for cyclohexanone. The temperature dependency of the oxygen solubility in cyclohexane 12,13 has also been taken into account.…”