CO2 capture in aqueous ammonia solutions: a computational chemistry perspective

Twenty-five transition structures (TS's) for CO(2) fixation by up to four base molecules (ammonia or ammonia + water) were located using M06-2X/6-311++G(d,p). All lead to either carbamate (NH(2)CO(2)(-)) or bicarbonate (HCO(3)(-)) products. Single-point energies at CCSD(T)/maug-cc-pVTZ//M06-2X/...

Full description

Saved in:
Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2012-12, Vol.14 (47), p.16301-16311
Main Authors: JACKSON, P, BESTE, A, ATTALLA, M. I
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
General and physical chemistry
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Twenty-five transition structures (TS's) for CO(2) fixation by up to four base molecules (ammonia or ammonia + water) were located using M06-2X/6-311++G(d,p). All lead to either carbamate (NH(2)CO(2)(-)) or bicarbonate (HCO(3)(-)) products. Single-point energies at CCSD(T)/maug-cc-pVTZ//M06-2X/6-311++G(d,p) were added to SM8/M06-2X/6-311++G(d,p) energies to obtain best-estimate aqueous activation energies. All theories agree that: (i) NH(2)CO(2)(-) formation has a lower free energy of activation (best est. 44-45 kJ mol(-1)) than HCO(3)(-) formation (best est. 86 kJ mol(-1)), and (ii) free energies of activation for CO(2) fixation are lowered when an ammonia molecule accepts the proton from the nucleophilic base. The theory also supports a key role for ammonium ions in the observed decomposition of NH(2)CO(2)(-) near pH 9.
ISSN:1463-9076
1463-9084
DOI:10.1039/c2cp43459h