Role of Hydrogen‐Bond Interactions in CO₂ Capture by Wet Phosphonium Formate Ionic Liquid: A Raman Spectroscopic Study

Abstract

The mechanism of CO absorption by a formate ionic liquid, [P ]HCOO, was studied by Raman spectroscopy. The band area for the symmetric CO stretching of the formate anion linearly decreases with the CO loading. From the slope of the decrease, 1 : 1 stoichiometry is proven between CO and the formate anion. The result favors the mechanism we proposed in a preceding work [J. Chem. Eng. Data 61, 837 (2016)]: HCOO +CO +H O→HCOOH+HCO →[HCOOH…HCO ]. Further support for the mechanism is obtained by the observation of antisymmetric vibration of CO for the proposed hydrogen-bonded complex between HCOOH and HCO . The bands appeared as a doublet (1677 and 1730 cm ) as this complex has two carbonyl groups. Based on DFT calculations, the [HCOOH…HCO ] complex is supposed to be the most abundant form of chemisorbed CO .

Pressure dependence in aqueous-based electrochemical CO2 reduction

“…10). In particular, a strong characteristic peak of HCOO − emerged at 1356 cm −1 , arising from the C−O symmetric stretch 35 , which could not be observed under the same conditions without applying a potential (Fig. 2a).…”

Pressure dependence in aqueous-based electrochemical CO2 reduction

“…10 ). In particular, a strong characteristic peak of HCOO − emerges at 1356 cm −1 , arising from the C − O symmetric stretch 46 , which cannot be observed under the same conditions without applying a potential (Fig. 2a ).…”

A depth-suitable and water-stable trap for CO2 capture

“…Bicarbonate is a reasonable explanation, and Yasaka et al considered that bicarbonate is stabilized by a hydrogen bond with a carboxylic acid. 25 However, those systems are viscous and not stable in water, and the CO 2 sorption shrinks down sharply with an increase in water concentration.…”

“…The energy change may come from crystallization, which forms new hydrogen bonds. 25 So, this reaction step is a part of the united hydrogen bond reaction. For tributyl- n -dodecylphosphonium-2-ethylhexylate (3) aqueous solution, after it reacts with CO 2 for 12 h, beside the solid, there is also a little organic liquid phase in the system (liquid–liquid–solid state), and this shows that the solid of 3 + CO 2 + H 2 O is not as stable as the solid of 2 + CO 2 + H 2 O.…”