The kinetics of the reaction of dimethyl carbonate (DMC) and phenol to methyl phenyl carbonate (MPC) and the subsequent disproportion and transesterification reaction of methyl phenyl carbonate (MPC) to diphenyl carbonate (DPC) have been studied. Experiments were carried out in a closed batch reactor in the temperature range from 160 to 200°C for initial reactant ratios of DMC/phenol from 0.25 to 3 and varying catalyst (titanium-(n-butoxide)) concentrations. The concept of a closed, ideally stirred, isothermal batch reactor incorporating an activity based reaction rate model has been used to fit kinetic parameters to the experimental data taking into account the catalyst concentration, the initial reactant ratio DMC/phenol and the temperature.

The oxidation of ferrous ions in acidic sulfate solutions at elevated air pressures was investigated. The effect of the Fe2+ concentration, initial H2SO4 concentration and partial oxygen pressure on the reaction rate were determined at three different temperatures, that is, T = 90, 70, and 50 °C. The effect on the reaction rate of the components that H2SO4 dissociates into, that is, HSO4 –, H3O+, and SO4 2–, was established as well. A second order of reaction in Fe2+ and a first order of reaction in O2 were determined. No clear order in either H2SO4 or the components H2SO4 dissociates into, could be established. For the experiments with initial concentrations of H2SO4 of 1 M and higher the oxidation rate was not affected, that is, a zero order of reaction in H2SO4 for these concentrations. Therefore, the kinetic rate expression for the oxidation of Fe2+ at concentrations of H2SO4 of 1 M and higher can be calculated with R Fe2+ = d­[Fe2+]/dt = k[Fe2+]2 P O2 , where the activation energy E A was determined to be 60.3 kJ/mol.

The oxidation of ferrous ions in acidic sulfate solutions in the presence of cupric ions at elevated air pressures was investigated in a high-intensity gas-liquid contactor. The study was required for the design of the regeneration steps of the novel Vitrisol V R desulphurization process. The effects of the Fe 2þ concentration, Cu 2þ concentration, Fe 3þ concentration, initial H 2 SO 4 concentration, and partial oxygen pressure on the reaction rate were determined at three different temperatures, i.e., T ¼ 50 C, 70 C, and 90 C. Most of the experiments were determined to be affected by the mass transfer of oxygen, and therefore true intrinsic kinetics could not be fully determined. An increase in Fe 2þ and Cu 2þ concentrations, as well as the partial pressure of oxygen and temperature, increased the Fe 2þ oxidation rate. H 2 SO 4 did not influence the Fe 2þ oxidation rate. An increase in Fe 3þ concentration decreased the Fe 2þ oxidation rate. Although determined from experiments partially affected by mass transfer, a first order of reaction in Fe 2þ was observed, fractional orders in both Cu 2þ and O 2 were measured, a zero order in H 2 SO 4 was determined, and a negative, fractional order in Fe 3þ was obtained. The activation energy was estimated to be 31.3 kJ/mol. KEYWORDS Gas-liquid reaction; H 2 S removal; Fe(II) oxidation; influence of Cu(II); mass transfer; reaction behavior Fe 2 ðSO 4 Þ 3 þ CuSðsÞ ! 2FeSO 4 þ CuSO 4 þ S o ðsÞ: (2)

The oxidation of ferrous ions in acidic sulfate solutions at elevated air pressures was investigated. The effect of the Fe2+ concentration, Fe3+ concentration, H2SO4 concentration, and partial oxygen pressure on the reaction rate were determined at three different temperatures, that is, T = 90, 70, and 50 °C. A second order of reaction in Fe2+ and a first order of reaction in O2 were determined, respectively. A slight inhibition by Fe3+ on the Fe2+ oxidation reaction was observed. The reaction is first order in Fe3+ in the kinetic term for the inhibition by Fe3+. Concentrations of H2SO4 up to 1 M result in a fractional negative order of −0.6; concentrations of H2SO4 above 1 M result in a zero order. One kinetic equation for the oxidation of Fe2+ was postulated, in which the order of reaction in H2SO4 is changed depending on the H2SO4 concentration. R FE2+ = −d­[Fe2+]/dt = k[Fe2+]2 P O2 [H2SO4] c /(1 + A[Fe3+]), with c = −0.6 for [H2SO4] < 1 M, and c = 0 for [H2SO4] > 1 M. The activation energy was determined to be E A = 62.1 kJ/mol. The order c in H2SO4 is either −0.6 or zero, depending on the H2SO4 concentration.