CO2 Absorption Rate into Concentrated Aqueous Monoethanolamine and Piperazine

• Published in: Journal of chemical and engineering data Vol. 56; no. 5; pp. 2187 - 2195
• Main Authors: Dugas, Ross E, Rochelle, Gary T
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.05.2011
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solutions; Gas absorption; Ethanolamine; Aminoalcohol; Piperazines; Mixed solvent; Carbon dioxide; Hydroorganic solvent
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je101234t

The CO2 equilibrium partial pressure and liquid film mass transfer coefficient (k g′) in (7, 9, 11, and 13) m monoethanolamine (MEA) and (2, 5, 8, and 12) m piperazine (PZ) were measured in a wetted wall column. Also examined was 7 m MEA/2 m PZ. Absorption and desorption experiments were performed at (40, 60, 80, and 100) °C over a range of CO2 loading. Amine concentration does not affect the CO2 partial pressure of PZ or MEA solutions as a function of CO2 loading with less than 0.45 mols CO2/mol alkalinity. Changes in amine concentration and temperature often do not affect the measured value of k g′. At higher temperature and CO2 loading in PZ, the diffusion of reactants and products limits CO2 transfer, and k g′ is depressed. PZ (8 m) exhibits a 70 % greater CO2 capacity than 7 m MEA and a 50 % greater CO2 capacity than 11 m MEA. k g′ decreases by a factor of 30 in aqueous MEA with 0.23 to 0.50 CO2 loading. k g′ decreases by a factor of 20 in aqueous PZ with 0.21 to 0.41 CO2 loading. PZ is shown to absorb CO2 2 to 3 times faster than MEA.