Influence of Hydrophobicity of Backbone Polymer in Thermo-responsive Hydrogel with Immobilized Amine on Cycle Capacity for Absorption and Recovery of CO.

The chemisorption process with amines is the major separation and recovery method of CO because of its high processing capacity and simplicity. However, large energy consumption for the desorption of CO is also associated with the process. To develop a separation and recovery process that is capable of desorbing CO at low temperatures and with minimal energy consumption, polymer hydrogels with a lower critical solution temperature (LCST) polymer network and amine groups immobilized in the polymer network of the hydrogels were exploited. Thermo-responsive amine gels with a series of hydrophobicity of polymer networks were systematically synthesized, and the influence of the hydrophobicity of the gels on the CO desorption temperature and cycle capacity (CO amount that can be separated and recovered by 1 cycle of temperature swing operation) was investigated using slurries with the series of gels. A significant decrease in the CO desorption temperature and increase in the cycle capacity occurred simultaneously by lowering the LCST of the gels via hydrophobisation of the polymer network. Based on an equilibrium adsorption model representing the CO separation and a recovery system with the gel slurries, an analysis of the system dynamics was performed in order to understand the recovery mechanism in the process.