Effects of Sodium Thiosulfate and Sodium Sulfide on the Corrosion Behavior of Carbon Steel in an MDEA-Based CO 2 Capture
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JMEPEG DOI: 10.1007/s11665-016-2458-9
Effects of Sodium Thiosulfate and Sodium Sulfide on the Corrosion Behavior of Carbon Steel in an MDEA-Based CO2 Capture Process W. Emori, S.L. Jiang, D.L. Duan, and Y.G. Zheng (Submitted July 25, 2016; in revised form October 19, 2016) The corrosion behavior of carbon steel has been tested in the presence of sodium thiosulfate and sodium sulfide in an MDEA-based CO2 capture system using electrochemical methods, weight loss measurements and surface analysis. The results of electrochemical measurements revealed that both thiosulfate and sulfide showed corrosion resistance properties to carbon steel corrosion. The corrosion resistance for the system with thiosulfate increased with concentration, while the system with sulfide yielded better corrosion resistance to carbon steel at lower concentrations as increase in sulfide concentration decreased the corrosion resistance. The corrosion inhibition behaviors for both systems at 0.05 M salt concentrations were confirmed by weight loss measurement, and the solution with sodium sulfide exhibited a better inhibition with time. Keywords
carbon steel, CO2 capture, CO2 corrosion, corrosion inhibition, MDEA, sulfide, thiosulfate
1. Introduction The chemical absorption method for carbon capture and storage (CCS) to reduce anthropogenic CO2 emission in industrial flue gas streams has become increasingly popular with time. The method typically involves the reaction of an absorbent with CO2 to form salts. After the capture process, CO2 is recovered by a reversal of the chemical reaction achieved by the application of heat, a reduction in pressure or both (Ref 1, 2). Many researchers have focused on the choice, potency and reliability of a number of absorbents particularly amine-based (Ref 3-11), as well as improvement of operations (Ref 12-18). Operating parameters such as amine concentration, dissolved CO2, process temperature and some amine degradation products have been highlighted to induce corrosion in postcombustion units (Ref 19). Although there are extensive research data available for post-combustion acid gas capture using amine solution, it is worthwhile to investigate the corrosivity effects of contaminants in the systems. The high level of oxygen, SOx and NOx in post-combustion acid gas capture becomes one of the primary routes for contaminant source where they either lead to the formation of heat-stable salts (Ref 20) or react with the amine to produce degradation products (Ref 6). Another source may be by direct contaminant introduction through make-up water (Ref 21).
W. Emori, S.L. Jiang, D.L. Duan, and Y.G. Zheng, CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, CAS, Shenyang 110016, PeopleÕs Republic of China. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
It is generally reported that both amine degradation products and heat-stable salts influence the corrosivity of amine solutions and that heat-stable salts reduce the acid gas removal capacity of the a
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