Chemical Engineering & Technology, Vol.29, No.9, 1084-1089, 2006
Chemisorptive removal of carbon dioxide from process streams using a reactive bubble column with simultaneous production of usable materials
In the context of attempts to improve the protection of the environment, a novel process where the carbon dioxide reacts rapidly with almost 100% conversion under mild conditions, is proposed. The chemisorptive process takes place in a slurry bubble column which operates with countercurrent flow, utilizing special solutions of primary long chain amines in a nonaqueous media. The product obtained is insoluble and separated by filtration. Because of its molecular structure, this product possesses tenside properties and can be used as an industrial additive. Typically the liquid phase consists of a mixture of hexadecylamine (C16H33NH2) or dodecylamine (C12H25NH2) in various concentrations with methanol or other alcohols as the solvent. Numerous parameters have been studied including different column heights, gas inlet compositions, gas flow rates and solvent type. Efficiencies of up to 99% are achievable for CO2 absorption, with methanol as the solvent. The second solvent examined, isopropanol, shows lower CO2 conversion rates. This can be attributed to its physical properties, mainly higher viscosity and hence, smaller mass transfer coefficient. In order to simulate real gas conditions, the influence of other sour gases, e.g., SO2 was also investigated experimentally. Because of coabsorption of the two gases, the CO2 efficiency was lower in this instance. In both solvents, the absorption efficiency with respect to SO2 is more than 99% due to its high solubility and reactivity. A complex mathematical model has been developed and applied to describe the mass and enthalpy transport in the reactive bubble column.