The Nature of Adsorbed CO sub(2) and Amine Sites on the Immobilized Amine Sorbents Regenerated by Industrial Boiler Steam

• Published in: Industrial & engineering chemistry research Vol. 52; no. 35; pp. 12530 - 12539-12530-12539
• Main Authors: Isenberg, Mathew, Chuang, Steven SC
• Format: Journal Article
• Language: English
• Published: 04.09.2013
• Subjects: Amines; Boilers; Carbon capture and storage; Carbon dioxide; Coal fired powerplants; Copper; Sorbents; Steam electric power generation
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie401892u

The nature of adsorbed CO sub(2) on immobilized amine sorbents regenerated with utility boiler steam was studied by in-situ infrared spectroscopy. The use of industrial boiler steam is the key factor lowering the overall operating cost of the immobilized amine CO sub(2) capture process for megawatt-scale coal-fired power plants. The industrial steam is known to contain trace amounts of Cu, Fe, and Zn species. The present study was undertaken to understand the chemistry occurring between the Cu contaminants in the steam and the amine sites on the sorbent. Cu-containing steam from the utility boilers resulted in a 91% loss of CO sub(2) capture capacity over 30 continuous CO sub(2) capture and regeneration cycles. UV-vis and in-situ IR studies suggest that the degraded sorbent contained Cu super(II) ions coordinated with nitrogen atoms of an imine species. These imine species are incapable of adsorbing CO sub(2). The remaining amine species could bind weakly with CO sub(2), mainly in the form of carbamic acid. The formation of ammonium ion species was inhibited by adsorbed Cu species on the degraded sorbent. Cu-free steam is required for stripping adsorbed CO sub(2) from the amine sorbent in the CO sub(2) capture process. The findings presented here should be considered before implementing a pilot-scale CO sub(2) capture process from coal-fired power plant flue gas.