Reversible Construction of Ionic Networks Through Cooperative Hydrogen Bonds for Efficient Ammonia Absorption

Abstract

ILs with reversible construction of ionic networks, which mainly consist of cooperative hydrogen bonds (CHBs) were designed for sigmoidal ammonia (NH3) absorption isotherm, which leads to efficient absorption, energy-saving desorption, and high reversibility. Combined with NH3 absorption–desorption experiments, spectroscopic investigations, NH3–TPD measurement, and quantum-chemical calculations, NH3 absorption mechanism was proposed as the hydrogen bond interaction with IL by overcoming the heat for disorganizing ionic networks, including CHBs breakage and the phase change of IL from solid to liquid. Reversely, the NH3 desorption would be promoted by the heat release for the reformation of ionic networks. Thereinto, [BzAm]­[Tf2N] with ionic networks showed NH3 absorption with threshold pressure at 0.28 bar and NH3 capacity of 2.8 mol NH3/mol IL at 1 bar as well as be desorpted completely just through pressure swing, calorimetric test indicated the exothermic reformation of ionic networks provided 31.8% of energy for NH3 desorption from [BzAm]­[Tf2N]. Furthermore, the ammonia capacity as well as the threshold pressure would be changed by varying the CHBs interaction in IL, that [2PyH]­[Tf2N] with weaker interaction of CHBs indicating decreased threshold pressure at 0.04 bar and enhanced NH3 capacity of 3.8 mol NH3/mol IL at 1 bar. We believe this highly efficient and reversible process by reversible construction of absorbents can provide a potential alternative for NH3 as well as other gas absorption.

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

“…Ionic liquids (ILs) possess many good properties, such as negligible vapor pressure, wide liquid temperature range, high thermal stability, and tunable properties. Because of their unique properties, ILs have been regarded as ideal absorbents for many gases in recent years. − Inspired by the reaction between NO and primary or secondary amines in the presence of a strong base under high NO pressure, − Wang et al reported chemisorption of NO by azole-based ILs, where the molar ratio of NO to IL was as high as 4.52 . After that, a number of works related to the capture and utilization of NO had been reported. − For example, Wu et al proposed the application of amino-acid-based ILs to the absorption of low-concentration NO, and the absorption capacity was 0.51 mol of NO per mol of IL .…”

Protic ionic liquid‐based deep eutectic solvents with multiple hydrogen bonding sites for efficient absorption of NH3

“…Ammonia (NH 3 ) is an important chemical raw material, especially in nitrogenous fertilizers and nitric acid 1,2 . However, NH 3 -containing gases released to air by fertilizer industries, fossil fuel combustion, refrigeration processes and so on [3][4][5] , also cause serious environmental issues by combining with NO x or SO x in atmosphere to form ammonium salts, a main component of PM2.5 (Particulate Matter 2.5) [6][7][8][9] . The traditional methods to remove NH 3 are water scrubbing and acid scrubbing, however, water scrubbing needs higher energy consumption for NH 3 recovery due to the high volatility of water, and acid absorption produces irreversible ammonium salts that does not satisfy the sustainable requirement 10 .…”

Process Simulation and Optimization of Ammonia-Containing Gas Separation and Ammonia Recovery with Ionic Liquids

“…Water scrubbing and acid scrubbing process are the main treatment technologies for NH 3 -containing tail gas treatment in industries. However, these technologies have several drawbacks such as high energy consumption, high purification cost, NH 3 -containing waste water discharge, solid waste pollution, equipment corrosion, and low NH 3 recovery ratio. , Recently, ionic liquid (IL) has been paid more attention and is considered as a favorable solvent for a green gas separation process because of its nonvolatility, thermal stability, programmability and tunability, which helps to reduce energy consumption and secondary pollution. , IL-based treatment processes are gaining popularity in the field of NH 3 separation and purification; − a few researchers have studied IL-based NH 3 absorption/adsorption using different ILs or related materials, for example, Yu et al developed a new IL-supported NH 3 adsorbent with good NH 3 selectivity and fast adsorption rate; Shang et al synthesized a new functional protic IL, which shows much higher NH 3 capacity than conventional ILs. Palomar et al used a computational experimental study to select ILs for NH 3 absorption.…”