- Title
- Toward rational design of amine solutions for PCC applications: the kinetics of the reaction of CO₂(aq) with cyclic and secondary amines in aqueous solution
- Creator
- Conway, William; Wang, Xiaoguang; Fernandes, Debra; Burns, Robert; Lawrance, Geoffrey; Puxty, Graeme; Maeder, Marcel
- Relation
- Environmental Science & Technology Vol. 46, Issue 13, p. 7422-7429
- Publisher Link
- http://dx.doi.org/10.1021/es300541t
- Publisher
- American Chemical Society
- Resource Type
- journal article
- Date
- 2012
- Description
- The kinetics of the fast reversible carbamate formation reaction of CO₂(aq) with a series of substituted cyclic secondary amines as well as the noncyclic secondary amine diethanolamine (DEA) has been investigated using the stopped-flow spectrophotometric technique at 25.0 °C. The kinetics of the slow parallel reversible reaction between HCO₃– and amine has also been determined for a number of the amines by ¹H NMR spectroscopy at 25.0 °C. The rate of the reversible reactions and the equilibrium constants for the formation of carbamic acid/carbamate from the reactions of CO₂ and HCO₃– with the amines are reported. In terms of the forward reaction of CO₂(aq) with amine, the order with increasing rate constants is as follows: diethanolamine (DEA) < morpholine (MORP) ∼ thiomorpholine (TMORP) < N-methylpiperazine (N-MPIPZ) < 4-piperidinemethanol (4-PIPDM) ∼ piperidine (PIPD) < pyrrolidine (PYR). Both 2-piperidinemethanol (2-PIPDM) and 2-piperidineethanol (2-PIPDE) do not form carbamates. For the carbamate forming amines a Brønsted correlation relating the protonation constant of the amine to the carbamic acid formation rate and equilibrium constants at 25.0 °C has been established. The overall suitability of an amine for PCC in terms of kinetics and energy is discussed.
- Subject
- amine solutions; PCC applications; CO₂(aq); kinetics
- Identifier
- http://hdl.handle.net/1959.13/1311598
- Identifier
- uon:22247
- Identifier
- ISSN:0013-936X
- Language
- eng
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