Author Faculty (Discipline)

Science

Document Type

Article

Publication Date

7-11-2014

Journal

Industrial & Engineering Chemistry Research

Volume Number

53

Issue Number

32

Page Numbers

12848-12855

ISSN

0888-5885

Embargo Period

7-23-2018

ANZSRC / FoR Code

03 CHEMICAL SCIENCES

Peer Review

Before publication

Abstract

Amino acid salts have greater potential for CO2 capture at high temperatures than typical amine-based absorbents because of their low volatility, high absorption rate, and high oxidative stability. The protonation constant (pKa) of an amino acid salt is crucial for CO2 capture, as it decreases with increasing absorption temperature. However, published pKa values of amino acid salts have usually been determined at ambient temperatures. In this study, the pKa values of 11 amino acid salts were determined in the temperature range of 298–353 K using a potentiometric titration method. The standard-state molar enthalpies (ΔHm0) and entropies (ΔSm0) of the protonation reactions were also determined by the van’t Hoff equation. It was found that sarcosine can maintain a higher pKa than the other amino acids studied at high temperatures. We also found that the CO2 solubilities and overall mass-transfer coefficients of 5 m′ sarcosinate (moles of sarcosine per kilogram of solution) at 333–353 K are higher than those of 30% MEA at 313–353 K. These results show that some possible benefits can be produced from the use of sarcosine as a fast solvent for CO2 absorption at high temperatures. However, the pronotation reaction of sarcosine is the least exothermic among those of all amino acids studied. This could lead to a high regeneration energy consumption in the sarcosinate-based CO2 capture process

Link to publisher version (DOI)

https://doi.org/10.1021/ie502256m

Comments

Used by permission: the author(s)

The document available for download is the accepted manuscript version of this article. The final published version may be accessed from the publisher here.

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