Investigation on Protic Ionic Liquids as Physical Solvents for Absorption of NO at Low Pressures

Abstract

Nitric oxide (NO) absorption in ionic liquids (ILs) is an interesting issue, but little attention has been focused on the removal of NO at low partial pressures. Herein, a series of protic ionic liquids (PILs) based on polyamines as the cation and hydroxybenzenes as the anion were prepared for capturing lowconcentration NO (0−0.6 bar). Triethylenetetramine phenolate ([TETAH][PhO]) showed an excellent absorption performance, with low viscosity, fast absorption rate, and high absorption capacity. The experimental solubility data were fitted by the Krichevsky−Kasarnovsky (K−K) equation, and the absorption enthalpy (ΔH) of NO in [TETAH][PhO] was thus calculated to be −43.60 kJ/mol. Density functional theory calculations were further performed to better understand the interaction of [TETAH][PhO] with NO on the molecular level, and the results suggest that the weak interaction of NO with the PIL was induced by the presence of H protons. It is believed that this work may provide a new method for the efficient and reversible absorption of low-concentration NO.

Absorption and Conversion of SO2 in Functional Ionic Liquids: Effect of Water on the Claus Reaction

“…The emission of sulfur dioxide (SO 2 ), which is mainly emitted from burning of coal, brings harm to not only the human body but also environmental safety. , Traditional flue gas desulfurization technologies, for example, limestone scrubbing, are deficient in absorbents regeneration and SO 2 utilization. − Ionic liquids (ILs), which have many superior properties, have been widely studied in gas separation. − Besides, ILs are promising reaction mediums because of their inherent catalytic reactivity for numerous reactions. − Among them, functional ILs with some special groups can chemically absorb SO 2 so that SO 2 with low concentrations (like 0.2 vol %) in flue gas can be removed efficiently. − Wang et al summarized the solubility of low-concentration SO 2 in various functional ILs . However, the chemical interactions between SO 2 and functional ILs are quite strong, which make it difficult to be regenerated.…”

Relationship between Structure and Properties of Nonstoichiometric Protic Ionic Liquids: n-Butylammonium Butyrate System

“…Protic ionic liquids (PILs) are a subclass of ionic liquids which are formed by proton transfer from Brønsted acids to Brønsted bases via the reaction HA + B = A – + BH + . Because of their low vapor pressure, good thermal stability, high ionic conductivity, , and protic nature, there are abundant applications, such as batteries, chemical synthesis, , gas capture, − extraction and separation, , and so on . Nonstoichiometric protic ionic liquids (PILs) are formed when precursor acid and base which are not equimolecular are mixed.…”