Mass transfer and kinetics of CO2 absorption into alkanolamines

Abstract

In recent years, global warming and climate change are the prime environmental issues caused by greenhouse gases (GHGs) emitted from various sources. CO2 is the major component, with approximately 60% share among GHGs. Currently, 85% of energy demand to the world is supplied by fossil fuels and major anthropogenic CO2 emission comes from coal-fired thermal power plants. The basic options to mitigate CO2 are efficient use of energy, progress on renewable energies and enhancing CO2 sequestration. Carbon capture and sequestration (CCS) is the major strategy that can be used to reduce CO2 emission. There are three methods for CCS: pre-combustion, postcombustion and oxy-fuel combustion. Among them, post-combustion is the most matured option because it offers flexibility and retrofitting option to existing power plant. Various capture technologies like absorption, adsorption, membrane separation, cryogenic, etc. are used for CO2 separation. Among various CO2 separation processes, absorption is the most commonly adopted option due to its higher CO2 removal efficiency and easy absorbent regeneration to get concentrated CO2 for reuse. In this chapter, the chemical absorption using alkanolamines and their different blended solutions has been emphasized through reaction mechanism and process chemistry of CO2 with alkanolamines, solubility of CO2 in single and blended alkanolamines, kinetics and related mass transfer phenomenon. CO2 solubility using various operating parameters such as partial pressure of CO2 in inlet gas stream, temperature of absorbent, contact time, absorbent concentration, etc. have been discussed. A comprehensive analysis of literature on kinetics of CO2 capture into alkanolamines (kinetic parameters, Arrhenius constants etc.) has been carried out. Mass transfer characteristics such as mass transfer coefficient, Henry’s law constant and two-film theory of mass transfer have been assessed for both gas and liquid phase. © 2016 Nova Science Publishers, Inc.