The kinetics of the reaction between CO2 and diethanolamine in aqueous ethyleneglycol at 298 K: a viscous gas—liquid reaction system for the determination of interfacial areas in gas—liquid contactors

The reaction between CO2 and diethanolamine (DEA) in aqueous ethyleneglycol (ETG) at 298 K has been studied over the complete composition range. The application of this reaction as a viscous gas—liquid system for the determination of interfacial areas in gas—liquid contactors by the chemical method is discussed. The reaction kinetics have been determined by mass transfer experiments of CO2 into solutions of DEA in aqueous ETG. To this end laboratory-scale stirred cell reactors with a flat surface have been used. In accordance with the same reaction in water at 298 K the reaction between CO2 and DEA in aqueous ETG at 298 K can be described by the zwitterion mechanism of Caplow. Special attention has been paid to the reversibility of the reaction between CO2 and DEA. Calculation show that the influence of the reversibility on the mass transfer rate can be neglected for partial pressures of CO2 below 3 kPa. It is demonstrated that the reaction between CO2 and DEA in aqueous ETG can be used for the determination of interfacial areas in gas—liquid contactors at higher viscosities

Development of catalytic hydrogenation reactors for the fine chemicals industry

A survey is given of the problems to be solved before catalytic hydrogenation reactors can be applied in a multiproduct plant in which selectivity problems are experienced. Some results are reported on work done on the reaction kinetics of two multistep model reactions and on mathematical modelling and experimental verification of the models. Since hydrogenation reactions are often very exothermic, cooling by solvent evaporation has been applied where appropriate. Sufficient information has been collected and correlated to enable operation of multiproduct catalytic reactors of the slurry or packed bubble column type; interdependence of operating variables is so complex that a mathematical model is indispensable

Residence time distribution of the gas phase in a mechanically agitated gas-liquid reactor

In this study we present a measuring method and extensive experimental data on the gas phase RTD in a mechanically agitated gas-liquid reactor with standard dimensions over a wide range of superficial gas velocities, agitation rates and agitator sizes. The results are modelled successfully, using the weighed moments method, by a simple RTD model of one mixer in series with a plug flow zone. All results are correlated in one relation, which can be used for scale-up

Interfacial areas and gas hold-ups in gas-liquid contactors at elevated pressures from 0.1 to 8.0 MPa

Interfacial areas and gas hold-ups have been determined at pressures up to 8.0 MPa in a mechanically agitated gas—liquid reactor and a bubble column with a diameter of 81 mm for superficial gas velocites between 1 and 5 and 1 and 10 cm/s, respectively. The interfacial areas have been determined by the chemical method using the model reaction between CO2 and aqueous diethanolamine (DEA). Contrary to earlier reported results on interfacial areas in a mechanically agitated reactor at pressures up to 1.7 MPa, a positive influence of pressure on the interfacial areas has been observed for higher pressures and higher superficial gas velocities. The product of the gas density G and the superficial gas velocity at the orifice υG, or was found to be an important parameter for the manifestation of the pressure effect. For values of GυG, or larger than 200 kg/m2 s the interfacial areas increase with increasing reactor pressure. Below this value of 200 kg/m2 s no influence of pressure could be observed. The gas hold-ups in the bubble column in water as well as in an aqueous solution of DEA with antifoam increase with increasing pressure. This pressure effect on the gas hold-up in bubble columns originates from the formation of smaller bubbles at the gas distributor. The relative increase in the gas hold-ups is smaller in water and also if a porous plate instead of a perforated plate is used as gas distributor. The differences in the magnitude of the pressure effect are caused by differences in the coalescence behaviour of the gas bubbles in both liquids and by differences in the bubble formation process at the two types of gas distributors, respectively. The interfacial areas in the bubble column also increase with increasing pressure. The relative increase in the interfacial areas aP/aatm with increasing pressure may be as large as 200% for a pressure increase from P = 0.15 to 8.0 MPa, depending on the type of gas distribution and the superficial gas velocity used