Highly Efficient and Reversible Absorption and Oxidation of Low-Concentration Nitric Oxide by Functionalized Ionic Liquids

Abstract

A novel method of using anion-functionalized ionic liquids (ILs) with high NO absorption capacity and reversibility for the capture and in situ oxidation of low-concentration NO was established. For the mixed gas containing 0.25% NO, the accumulation rate of nitric acid in these ILs was significantly higher than that in the conventional ILs; after absorption and oxidation reached equilibrium, the molar ratio of HNO 3 to [P 4446 ][PhSO 3 ] was 0.86, which was 5 times as high as that of the conventional IL. Therefore, the problems of low efficiency and poor reversibility of traditional ILs in the absorption and oxidation process were solved. Through absorption and oxidation experiments, quantum chemical calculation, NMR, and time-resolved in situ ATR-FTIR spectroscopic investigation, the results demonstrated that such a high accumulation rate of HNO 3 originated from high uptake of NO through multiple-site interaction. Moreover, high reversibility is attributed to low volatility of conjugated acid of anions and decreased basicity of O sites on anions. We believe that such highly efficient and reversible conversion of low-concentration NO to HNO 3 by ILs provides a new strategy for improving atomic economy of fossil fuel combustion, that is, converting post-combustion pollutants to good valuable chemicals.

Study on Mechanism and Thermodynamics of NO Absorption by Acetylcholine‐chloride Type Deep Eutectic Solvents

“…The new peak at 1299 cm −1 was the N−O bond stretching vibration peak in the −NONO structure. The last peak at 1005 cm −1 was the N− bond stretching vibration peak [22,31,32] …”

“…The last peak at 1005 cm À 1 was the NÀ bond stretching vibration peak. [22,31,32] The mechanism of NO absorption by acetylcholine-chloridetype DES was investigated by comparing the 1 H NMR spectra of DES before and after NO gas absorption. The 1 H NMR spectra of acetylcholine-methyl urea DES before and after NO absorption are presented in the Figure 6.…”

“…The frequency analysis was conducted to verify the optimized structures, minima on the potential energy surface, and represented no imaginary frequencies at the same theoretical level. [31,39]…”

Combined Superbase Ionic Liquid Approach to Separate CO2 from Flue Gas

“…This technology has the potential to be applied to NO x removal, as well as SO 2 . A number of ILs, including [P 66614 ]­[Tetz], have been shown to display large “working” capacities for NO, presenting an opportunity for removing both contaminants simultaneously through multisite absorption capability. ,− However, it is essential to study conditions that are representative of real-world environments to assess the impact of realistic amounts of flue gas contaminants on the ability of IL sorbents to reversibly capture CO 2 . − Gas capture in thin films of ILs, such as [P 66614 ]­[Benzim], is also being investigated as studies have shown that their behavior differs in comparison to bulk solution …”

NH3 production from absorbed NO with synergistic catalysis of Pd/C and functionalized ionic liquids

“…In recent years, ionic liquids (ILs) have been widely used in the field of gas absorption due to their advantages of low vapor pressure, adjustable structure and recyclability. 19,20 For example, amino acid-based ILs, 21 imidazolium-based ILs 22 and carboxyl-based ILs 23 could absorb low-concentration NO with high efficiency. However, most studies only used ILs to absorb NO, and then the NO was desorbed by vacuum flash evaporation at high temperatures, which usually results in high energy consumption and prevents the effective utilization of NO resources.…”