In-situ synthesis of useful polyamines for CO2 capture from piperazine

Omkar Namjoshi, Yang Du, Han Li, Mark Goldman, Gary Rochelle

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Concentrated piperazine (PZ) is considered to be a promising solvent for use in post-combustion CO2 capture from coal-derived flue gas due to its fast rate of CO2 absorption, high CO2 capacity, and low degradation rates. However, this solvent has a limited solubility window at conditions corresponding to the operating temperature of a CO2 capture plant, limiting its use in commercial CO2 capture systems. Blending PZ with a triamine analogue of PZ, such as aminoethylpiperazine (AEP), can widen the solubility window while maintaining many of the properties that make concentrated PZ attractive. With the exception of AEP, many of the triamine PZ analogues are expensive and are not commercially available. They can, however, be made in-situ in the regeneration section of the CO2 capture plant by the selective reaction of PZ with an amine that forms an oxazolidinone (either a primary or secondary alkanolamine) as its initial thermal degradation byproduct. The data suggests that the structure of the oxazolidinone is a strong function of reactivity with PZ. Increasing steric hindrance - such as increasing the chain length between the amino group or hydroxyl group or by adding alkyl functional groups to the carbon chain between the hydroxyl and amino groups - can reduce reaction rates by a factor of three to five. Secondary amines that form oxazolidinones react four times as fast as primary oxazolidinone-forming amines. Piperazine and solvent alkalinity losses are reduced significantly (∼0.2%/week) once the oxazolidinone-forming amine is completely consumed, indicating that the synthesized amine blend is thermally stable.

Original languageEnglish (US)
Title of host publicationAIChE 2012 - 2012 AIChE Annual Meeting, Conference Proceedings
StatePublished - 2012
Externally publishedYes
Event2012 AIChE Annual Meeting, AIChE 2012 - Pittsburgh, PA, United States
Duration: Oct 28 2012Nov 2 2012

Publication series

NameAIChE Annual Meeting, Conference Proceedings


Other2012 AIChE Annual Meeting, AIChE 2012
Country/TerritoryUnited States
CityPittsburgh, PA


  • Amine synthesis
  • Carbon capture
  • Oxazolidinones
  • Piperazine

ASJC Scopus subject areas

  • General Chemical Engineering
  • General Chemistry


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