Heat-Stable Salts and Methods for Their Removal from Alkanolamine Carbon Dioxide Absorbents (Review)

Abstract

Absorption using aqueous solutions of alkanolamines is the most widely used procedure for removal of carbon dioxide from natural gas, flue gases from power-generating facilities, and other mixtures. Its main drawback is degradation/deactivation of alkanolamine under the process conditions (high temperatures, presence of oxygen and other impurities) with the formation of heat-stable salts consisting of alkanolammonium cation and anions of organic and inorganic acids. The main operation problems caused by heat-stable salts are considered in the review. Three main methods for removal of heat-stable salts from alkanolamine adsorbents are described in detail: distillation, ion exchange, and electrodialysis. The main characteristics of these methods and their advantages and drawbacks are described, and a comparative analysis is made. The history and state-of-the art of studies within the framework of each method are presented.