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New Reactive Extraction Based Reclaiming Technique for Amines Used in Carbon Dioxide Capture Process from Industrial Flue Gases

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journal contribution
posted on 07.04.2016, 00:00 by Phattara Akkarachalanont, Chintana Saiwan, Teeradet Supap, Raphael Idem, Paitoon Tontiwachwuthikul
A new reclaiming technique based on reactive extraction for removal of heat stable salts (HSS) from monoethanolamine (MEA) used in carbon dioxide (CO2) capture process has been developed. The extraction process was based on the use of tri-n-octylamine (TOA), Aliquat 336, OH modified Aliquat 336, a two-step extraction (modified Aliquat followed by TOA), and mixed extractant (modified Aliquat and TOA) in 1-octanol diluent. The best parameters were 69% OH modified Aliquat, two-step extraction, and mixed extractant (modified Aliquat and TOA) and under optimum extraction conditions were able to improve the extraction efficiency of the original Aliquat and TOA to over 90%. The two-step extraction and mixed extractant were also capable of managing Cl contamination in MEA solution. Extraction was found to be independent of temperature whereas efficiency reduced with increase of CO2 loading. Therefore, it is recommended to apply this extraction technique to the lean MEA stream after the rich/lean heat exchanger either with or without cooling. Regeneration of used extractant (OH Aliquat) was implemented and optimized with the use of 4 kmol/m3 NaOH. In addition to HSS removal, the new extraction technique was also able to remove major nonionic degradation products also by up to 90%.