The performance and efficiency of a chemical reactor with respect of conversion and selectivity depend on the intrinsic kinetics of the various chemical reactions, and on physical rate processes such as intraphase mass and heat transfer. The effects of these chemical and physical rate processes in turn depend upon the non-ideal flow behavior of the various phases in the reactor. Many gas-liquid reactions of industrial importance are carried out in bubble column reactors including chlorination of organic compounds, ammination of fatty acids, oxidation of molecular pollution abatement. Such reactors are simple and inexpensive to operate, do not have any moving parts, and it is easy to vary liquid residence time. Bubble columns are difficult to design because their complex flow characteristics combined with the reaction kinetics result in a system whose behavior can not be predicted a priori based on data from another column of, for example, different size, flow regime, or gas holdup. One factor that contributes to this problem is gas phase backmixing which results from partial recycling of the gas phase which is in turn reflected in the residence time distribution of the gas phase. In this work the PI will attempt to propose and experimentally verify a new correlation to compute gas phase backmixing in bubble column reactors. He plans to use a mass spectrometer to measure gas phase dispersion in two separate columns of different diameters. Two reactions will be run in each column which represent typical reacting systems carried out in bubble column: (1) cobalt-catalyzed oxidation of sodium sulfite solutions by air and (2) absorption of CO2 (diluted with air) in alkaline buffer solution. The gas dispersion data will be utilized to create a comprehensive model incorporating the effect of physical properties of the liquid, the diameter of the column, and the superficial gas and liquid velocities in an equation for gas phase mixing in bubble columns.
