Innovative Carbon Dioxide‐Capturing Organic Solvent: Reaction Mechanism and Kinetics

Abstract

The reaction rates of CO 2 with an innovative CO 2 -capturing organic solvent (CO 2 COS), consisting of blends of 2-tert-butyl-1,1,3,3-tetramethylguanidine (BTMG) and 1-propanol, were obtained as function of BTMG concentration and temperature. A stopped-flow apparatus with conductivity detection was used. The reaction was modeled by means of a modified termolecular reaction mechanism which resulted in a second-order rate constant, and activation energies were calculated for a defined temperature range. Quantum chemical calculations at the B3LYP/6-31G(d) level also produced the activation energy of this reaction system which strongly supports the experimental findings.

Theoretical investigation of carbon dioxide capture by aqueous boric acid solution: A termolecular reaction mechanism

“…A similar termolecular reaction mechanism which was previously suggested in our studies for similar carbon dioxide capturing systems [18][19][20] can be adapted to current reaction system which contains boric acid, carbon dioxide and water. different concentrations are also used in the carbon dioxide capture [21][22][23][24][25].…”

“…As a continuation to our studies on the CO 2 capture [18][19][20]27], in which CO 2 was captured by different amine-alcohol mixtures through a single step termolecular mechanism as explained above [18][19][20] and also CO 2 was trapped between the amorphous form or crystalline ice slab of the water and methylamine [27], an alternative single step termolecular reaction mechanism among carbon dioxide, boric acid and water is suggested in the current study, and the methodology used and results obtained are given in the following sections.…”

“…Other than amine based solvent and alcohol mixtures, aqueous potassium carbonate and boric acid mixtures at the B3LYP/6-31G(d) level of theory [28][29][30][31][32]. This level calculations yielded well results in our previously performed similar reaction mechanism studies [18][19][20]. After obtaining the most stable isolated structures of the boric acid, CO 2 and water molecules, reactant and product systems for the interaction of these molecules according to the termolecular reaction mechanism are prepared.…”

“…Recently, in our combined experimental and theoretical studies, we followed the single step termolecular reaction mechanism for the capture of carbon dioxide by 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN)/1-propanol and 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD)/1butanol mixtures [18], DBN/1-hexanol, TBD/1-hexanol and 2-tert-butyl-1,1,3,3-tetramethylguanidine (BTMG)/ 1-hexanol mixtures [19], and BTMG/1-propanol mixture [20]. Our findings in these combined experimental and theoretical studies [18,19,20] were in good agreement and our results suggested that the reaction among carbon dioxide, amine based organic solvent and alcohol takes place very likely according to the single step termolecular mechanism. Other than amine based solvent and alcohol mixtures, aqueous potassium carbonate and boric acid mixtures at the B3LYP/6-31G(d) level of theory [28][29][30][31][32].…”

Effect of 1‐Methylimidazole on CO2 Absorption by Diethylenetriamine Aqueous Solutions

“…The absorption process by an aqueous amine solvent is the most common one for CO 2 capturing from postcombustion flue gases due to its high flexibility for existing power plants . Although aqueous amine solvents such as monoethanolamine (MEA), methyldiethanolamine (MDEA), and piperazine (PZ) are known to be effective for the chemical absorption of CO 2 , they require high amounts of energy during the solvent regeneration step due to the large latent heat of water , .…”