Reaction Kinetics of Carbonyl Sulfide (COS) with Diethanolamine in Methanolic Solutions

Abstract

In this work, the kinetics of carbonyl sulfide (COS) absorption in a hybrid solvent containing diethanolamine (DEA) dissolved in methanol was studied. The amine concentrations and temperatures ranged from 380 to 2030 mol m−3 and from 298 to 323 K, respectively. With the purpose of estimating reaction rate constants for the COS−DEA system, the rigorous modeling of COS absorption was carried out based on the two-step zwitterion mechanism, used until now in the modeling of the absorption of carbon dioxide and sulfur compounds by alkanolamine aqueous solutions. A downhill simplex optimization method was developed to determine the reaction rate constants, and simultaneously an iterative procedure was followed to estimate the enhancement factor of the COS absorption. As the results show, these optimization procedures led successfully to the appropriate fitting between the experimental and modeled data and also confirm the two-step zwitterion mechanism for this absorption system.