Mass transfer with complex reversible chemical reactions—II. parallel reversible chemical reactions

An absorption model has been developed which can be used to calculate rapidly absorption rates for the phenomenon mass transfer accompanied by multiple complex parallel reversible chemical reactions. This model can be applied for the calculation of the mass transfer rates, enhancement factors and concentration profiles for a wide range of processes and conditions, for both film and penetration model. With the aid of this mass transfer model it is demonstrated that the absorption rates in systems with multiple reversible reactions can be substantially greater than the summation of the absorption rates derived for the single systems. This latter fact provides a scienctific basis for the application of aqueous mixed amine solutions for industrial sour gas treating. Also it is shown that for kinetic studies by means of abosorption experiments for reversible reactions the presence of small amounts of fast reacting contaminants can have an overruling effect on the outcome of the determination of the reaction kinetics. It is shown that the concepts of shuttle mechanism and homogeneous catalysis refer to asymptotic situations,for practical situations intermediate behaviour was observed which was previously not accessible for analysis. Experimentally determined absorption rates of CO2 in aqueous solutions of various mixtures of alkanolamines (MMEA-MDEA, MEA-MDEA, DIPA-MDEA and MEA-DEA-MDEA) can be prdicted extremely well for the several mass transfer regimes which were studied experimentally. The experiments were carried out in a stirred vessel with a flat surface over a wide range of process conditions.