5. Conclusions
The establishment of a molecularly correct mechanism for the formation of carbamates from CO2/carbonates and
primary amines is of fundamental importance, it is basic physical organic chemistry. It is also highly relevant for
amine-based post combustion capture.
PCC is necessarily a cyclic process where the amine solution is absorbing CO2 under one set of conditions, releasing
it under a different set and then recycled to absorb again. Temperature is the most likely candidate for driving the
cycle, but it could at least theoretically also be a cyclic pressure regime. Whatever the process is, the accurate
knowledge of all chemical processes involved is invaluable.
Presently the rate and equilibrium constants for MEA have only been determined in this way at one temparature
(and pressure). The determination of the activation parameters for all rate constants and reaction entropies and
enthalpies for all equilibria is recquired for the complete modelling of an absorber plant. Of particular importance
are the reaction enthalpies as they define the ultimately important energy consumption per unit of absorbed CO2.
An additional advantage of fundamental understanding is the possibility of rational design of new chemicals such as
amines or parts of the process conditions such as concentrations, temperature profiles, and addition of supporting
chemicals such as acids and bases.
5. Conclusions The establishment of a molecularly correct mechanism for the formation of carbamates from CO2/carbonates and primary amines is of fundamental importance, it is basic physical organic chemistry. It is also highly relevant for amine-based post combustion capture. PCC is necessarily a cyclic process where the amine solution is absorbing CO2 under one set of conditions, releasing it under a different set and then recycled to absorb again. Temperature is the most likely candidate for driving the cycle, but it could at least theoretically also be a cyclic pressure regime. Whatever the process is, the accurate knowledge of all chemical processes involved is invaluable. Presently the rate and equilibrium constants for MEA have only been determined in this way at one temparature (and pressure). The determination of the activation parameters for all rate constants and reaction entropies and enthalpies for all equilibria is recquired for the complete modelling of an absorber plant. Of particular importance are the reaction enthalpies as they define the ultimately important energy consumption per unit of absorbed CO2.An additional advantage of fundamental understanding is the possibility of rational design of new chemicals such as amines or parts of the process conditions such as concentrations, temperature profiles, and addition of supporting chemicals such as acids and bases.
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