Gas–Liquid Reaction Kinetics: A Review of Determination Methods PRAKASH D. VAIDYA AND EUGENY Y. KENIG Department of Biochemical and Chemical Engineering, University of Dortmund, Dortmund, Germany The aim of this article is to provide comprehensive insight into the determination and interpretation of reaction kinetics of two-phase (gas–liquid) systems. Various aspects of the methodologies used for the measurements of kinetic parameters (such as equipment design, corresponding theoretical background, main steps, advantages, and limitations) are discussed in detail. In addition, an illustrating example is provided based on an industrially relevant absorption system. Keywords Absorption; Gas-liquid reactions; Reaction kinetics Introduction Gas-liquid reactions have received considerable attention by both academicians and industry. Some examples of industrial relevance are absorption of CO 2 into aqueous alkanolamines, absorption of H 2 S into ferric sulphate solutions, absorption of NO or NO 2 into solutions containing reactive species, absorption of O 2 in sodium sul- phite solutions, hydrogenation of olefins using homogeneous catalysts, recovery of iso-butylene from C 4 streams (by selective absorption in sulphuric acid), and chlori- nation in aqueous solutions containing phenol and substituted phenols. A detailed knowledge of reaction kinetics for such reaction systems is essential for the design of suitable reactors and prediction of reactor performance. Absorption experiments are therefore performed on a laboratory scale to facilitate fundamental understand- ing of these reactions, to study the effect of the chemical reaction on mass transfer rates, and to describe the reaction rate as a function of process variables, e.g., tem- perature and reactant concentration. Such bench-scale kinetic experiments are performed in the range of temperatures and concentrations typical for industrial absorbers. Danckwerts (1970) and Doraiswamy and Sharma (1984) have earlier out- lined the theory of mass transfer with chemical reaction and suggested models that can be employed to study the kinetics of gas–liquid reaction systems. Experimental techniques used to obtain the kinetic data for such systems may differ. Further, experimental measurements may at times be erroneous. In addition, different theoretical models can be used for the parameter treatment. Hence, even for identical conditions, some deviations in estimated kinetic parameters may arise in different investigations. Aboudheir et al. (2003) compiled literature data on the reac- tion between CO 2 and aqueous monoethanolamine (MEA) and showed that the Address correspondence to Eugeny Y. Kenig, Department of Biochemical and Chemical Engineering, University of Dortmund, 44227 Dortmund, Germany. E-mail: e.kenig@bci. uni-dortmund.de Chem. Eng. Comm., 194:1543–1565, 2007 Copyright # Taylor & Francis Group, LLC ISSN: 0098-6445 print/1563-5201 online DOI: 10.1080/00986440701518314 1543