CO2 capture from ambient air via crystallization with tetraalkylammonium hydroxides. Issue 46 (8th November 2022)

• Record Type: Journal Article
• Authors: Mishra, Manish Kumar; Smetana, Volodymyr; Hiti, Ethan A.; Wineinger, Hannah B.; Qu, Fengrui; Mudring, Anja-Verena; Rogers, Robin D.
• Is Part Of: Dalton transactions. Volume 51:Issue 46(2022)
• Page Start: 17724
• Page End: 17732
• Publication Date: 2022-11-08
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d2dt02262a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Aqueous solutions of tetra( n -alkyl)ammonium hydroxides, [N nnnn ][OH] with n = 2: n -ethyl, 3: n -propyl, 4: n -butyl are effective in direct air carbon capture (DAC) with high CO2 /[N nnnn ][OH] ratio. Abstract : Aqueous solutions of a series of short carbon chain tetra( n -alkyl)ammonium hydroxides, [N nnnn ][OH] with n = 2: n -ethyl, 3: n -propyl, 4: n -butyl, have been serendipitously found to be potential candidates for direct air carbon capture (DAC) when being used as reagents in more complicated reactions. Aqueous solutions of [N3333 ][OH], [N2222 ][OH], or [N3333 ][OH] with UO2 SO4 ·3H2 O and 1, 4-diamidoximylbenzene, and [N4444 ][OH] with cytosine (HCyt) directly absorb CO2 from the atmosphere upon mild heating in the open atmosphere crystallizing in complexes reaching up to 2 : 1 CO2 /[N nnnn ]OH ratio. [N2222 ][HCO3 ]·3H2 O (1 ), [N2222 ]2 [H(HCO3 )3 ]·5H2 O (2 ), [N3333 ][HCO3 ]·0.5H2 O (3 ), [N3333 ][H(HCO3 )2 ] (4 ), [N3333 ]2 [(tpa)(H2 CO3 )2 ] (5 ; tpa = terephthalate), [N4444 ][H(Cyt)(HCO3 )]·H2 O (6 ) and [N4444 ][H2 (Cyt)2 (HCO3 )]·H2 O (7 ) have been isolated in crystalline form and structurally characterized by single crystal X-ray diffraction. The compounds are characterized by complex polyanionic formations from bicarbonate dimers ([(HCO3 )2 ·(H2 O)]2 4− ) or chains ([H(HCO3 )2 ] n n − or [H2 (tpa)(HCO3 )2 ] n 2 n − ) to water-bicarbonate associates ([(HCO3 )2 ·6H2 O] 2− and [(H2 CO3 ·(HCO3 )2 )2 ·6H2 O·2H2 O] 2− ) and three-component anionic layers ([H(Cyt)(HCO3 )·H2 O] n n − and [H2 (Cyt)2 (HCO3 )·H2 O] n n − ) frequently showing proton sharing. While some hydroxides themselves can maintain a high CO2 /[N nnnn ][OH] ratio, particularly 2 and 4, the presence of secondary hydrogen bond donors/acceptors may increase the sorption efficiency through decreased solubility and enhanced crystallization.