EP4626877A1

EP4626877A1 - Nicotine-based ionic liquids for water vapor removal

Info

Publication number: EP4626877A1
Application number: EP23818315.6A
Authority: EP
Inventors: Theofilos IOANNIDES; Vassilios DRACOPOULOS; Dionisios VROULIAS
Original assignee: Foundation of Research and Technology Hellas/ Institute of Chemical Engineering Sciences (FORTH/ICE-HT)
Current assignee: Foundation of Research and Technology Hellas/ Institute of Chemical Engineering Sciences (FORTH/ICE-HT)
Priority date: 2022-12-01
Filing date: 2023-11-27
Publication date: 2025-10-08
Also published as: WO2024115403A1; GR20220100996A

Abstract

The invention relates to water vapor removal (dehumidification) with the use of ionic liquids. Membranes prepared from these ionic liquids can be useful for the removal of water vapor in isothermal processes, including dehumidification of natural gas and biogas, dehumidification of flue gas, removal of water vapor from reactive gas streams, and dehumidification of atmospheric air during ventilation and air conditioning applications and systems.

Description

NICOTINE-BASED IONIC LIQUIDS FOR WATER VAPOR REMOVAL

DESCRIPTION

Technical Field of Invention

The present invention relates generally to water vapor removal (dehumidification) from gaseous streams, including natural gas, biogas, flue gas, industrial process streams and humidified air by combining membrane technology with ionic liquids.

Background of Invention

Natural gas is a relatively clean burning fossil fuel, accounting for 24.7% of total primary energy consumption¹. However, natural gas produced from gas wells and biogas produced by fermentation processes is saturated with water vapor. Water along with the presence of gases like CH4, C2H6, CO2 and H2S lead to the formation of ice-like crystalline solids called gas hydrates². These hydrates are responsible for the plugging of pipelines leading to the blockage of natural gas (or biogas) distribution². As a result, natural gas (or biogas) dehydration (typically up to 7 Ib/MMscf) is mandatory in any natural gas (or biogas) plant.

Apart from natural gas, coal is another fossil fuel, accounting for 27.2% of total primary energy consumption¹. Both natural gas and coal are used in combustion processes for power generation. The produced flue gas contains mainly CO2, N2, O2, water vapor and air pollutants (SO2, NOx and fly ash). Besides the emission of CO2 in the atmosphere, CO2 can be used in CO2 utilisation processes such as food and beverage industry and chemical production (e.g., methanol, urea). Thus, cleaning of flue gas is essential. A selective catalytic reduction process is used to convert NO_X into N2 and water, SO2 is removed with a desulfurization unit and ash particles are trapped with an electrostatic precipitator³. During all these cleaning steps, gas stream becomes saturated with water, causing corrosion problems. As a result, flue gas dehydration is also essential in any power plant, and it is important before entering utilisation facilities. Another application, where N2 or air dehumidification is important, is ventilation and air- conditioning systems. In most countries, air-conditioning systems are very common features in buildings for maintaining thermal comfort. In 2013, the air-conditioning market was estimated to be over US$91.6 billion, including unit sales, new installation, equipment, and replacement of the existing units³. It is estimated that by 2050 the energy cooling demand for air-conditioning services will be tripled due to the ambient temperature increase⁴.

Another application refers to removal of water vapor from industrial gaseous process streams. Examples of such streams include the hydrogen-rich reformate gas produced from steam reforming of methane or other hydrocarbons. In addition, selective removal of water vapor from reactive gas streams could promote the yield of equilibrium-limited chemical reactions, in which water is among the reaction products.

The three most common water vapor removal methods are absorption by liquid desiccants, adsorption by solid desiccants and vapor condensation by lowering the temperature using a heat-exchanger or employing the Joule-Thompson (JT) effect⁵. The state-of-the-art technology for gas dehydration is based on absorption by liquid desiccants. Glycol solutions such as mono-ethylene glycol (EG), and triethylene glycol (TEG), are the most common liquid desiccants used in dehydration units due to their high-water affinity, low solubility in gas and low vapor pressure⁶. However, this technology faces environmental problems due to gas loss from pneumatic controllers and decomposition of glycols in regeneration boilers, emitting hazardous air pollutants, benzene, toluene, ethylbenzene, and xylenes (BTEX) in case of natural gas dehydration⁷. Other disadvantages are the complexity of the operating system (separator, absorber, filter, reboiler, heat exchangers) and the high maintenance cost⁷. Although other technologies such as dehydration based on adsorption by solid desiccants (e.g., calcium chloride, silica gel, alumina, zeolites) or dehydration based on condensation employing the Joule-Thompson effect have less maintenance costs, absorption is more suitable due to less demanding heating requirements⁸.

Regarding air conditioning technologies, the indirect evaporative cooler is the most economical choice, but it requires a low outdoor air humidity as its performance degrades when the air humidity is high. Membranes

Membranes are an alternative technology with high potential for water vapor removal. Membrane units are economically attractive mainly in smaller scales (lower than 10 MMscf/d) but their modular nature renders them also adaptable to larger scales¹⁰. In all cases, highly permeable and selective membranes with a long lifetime are desirable.

This invention focuses on the combination of nicotine-derived ionic liquids (ILs) with membrane-based technology. ILs are salts composed of an organic cation and an inorganic anion, with melting point below 100 °C. During the last two decades, ILs have gained attention due to their wide liquid range, low volatility, non-flammability, high thermal and water stability, and simple regeneration¹¹. It has also been reported that properties and especially the water solubility of ILs can be tuned by changing the chemical structure of the cation and/or selection of a more hydrophilic counter anion¹². For this reason, various nicotine-derived ILs with different anion are included in this invention focusing on water vapor removal in combination with membrane technology.

It is not intended to limit the invention to the forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the invention.

Regarding dehumidification, dehydration or drying of gases and process streams and operation of air-conditioning systems, using membranes is an attractive alternative technology due to its many benefits, as referred in the background of the invention. In this process, a humidified gas mixture passes over a membrane surface at ambient pressure and on the opposite side, a vacuum pressure is applied. Thus, a driving force is created for water vapor to pass through the membrane. Over the last two decades, many types of materials have been explored as perm selective membranes for water vapor removal processes.

The most common commercial hydrophilic glassy polymer applied in dehydration membranes is cellulose acetate with a water vapor permeability of 1 x 10⁵ Barrer (extrapolated to zero water activity) and H2O/CH4 selectivity of 1.9 x 10⁵ at room temperature and ambient pressure⁸. Polyimides (e g., Kapton) is another commercial type of membrane proposed for H2O/CH4 separation. Among polyimides, sulfonated polyamideimide) (BDSA-40%) is almost as water vapor permeable as cellulose acetate with H2O/CH4 selectivity of 1.6 x 10⁶ (extrapolated to zero water activity) under the same conditions¹³. However, condensed water can damage cellulose acetate membranes and it can decrease the performance of polyimides during operation¹⁰.

MTR Inc. has developed thin film composite membranes based on a block copolymer made up of rigid polyamide blocks and soft polyether blocks, commercially available with the trademark Pebax®. H2O permeance was 0.055 m³(STP)/(m² h bar) at 30-60 bar¹⁴. However, the H2O/CH4 selectivity was very low making Pebax® polymer not applicable for natural gas dehydration. Among other rubbery polymers, a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer, commercially available under the name Nafion® 117, exhibits very high-water vapor permeability (4.1 x 10⁵ Barrer) at 30-35 °C and 1 atm with selectivity one order of magnitude higher than permeability (extrapolated to zero water activity)¹³. This polymer is yet to be applied in commercial membrane units, mainly due to its poor mechanical properties for operation at high pressures.

There are also a couple of polymer membranes tested at lab-scale, PIL-MeSC (main chain pyridine containing aromatic polyethers) and PEGMA-9502 (amphiphilic tercopolymer comprising polyacrylonitrile, polyethylene glycol) methyl ether methacrylate, and poly(N,N-dimethyl amino ethyl methacrylate) segments) with water vapor permeability of 1.8 x 10⁵ Barrer and 1.7 x 10⁵ Barrer, respectively and H2O/CH4 selectivity of 1.8 x 10⁵ for both polymers at room temperature and ambient pressure^15,16. The performance of these membranes has been tested only under laboratory conditions.

Until now, only Air Liquide has employed membrane technology for natural gas dehydration. The PEEK-Sep™ or PoroGen membranes are asymmetric hollow fibers based on porous polyether ether ketone (PEEK)¹². They are formed by melt extrusion process with a 12-inch module containing 0.5-1.0 x 10⁶ PEEK fibers¹⁷. The PEEK polymer exhibits extremely high-water vapor permeability of 6.1 x 10⁵ Barrer, thermal (max. 239 - 260 °C) and mechanical strength (tensile strength of 7 x 10⁷ - 1 x 10⁸ Pa), chemical resistance, and a CO2 footprint of 12.3 - 13.6 kg CCh/kg PEEK, making them applicable in natural gas dehydration¹⁸.

Table 1 contains hydrophilic polymers typically proposed for air dehumidification and flue gas dehydration along with other lab tested polymers reported recently. Among all polymers, the lab tested sulfonated styrenic pentablock copolymer, Nexar synthesized in THF solution is the most permeable to water vapor (5.5 x 10⁵ Barrer) with a H2O/N2 selectivity of 1.5 x 10⁶. Although, the sulfonated poly(ether ether ketone) (SPEEK) polymer is almost one order of magnitude less water vapor permeable, its H2O/N2 selectivity is 1 x 10⁷, the highest reported so far. Regarding H2O/CO2 separation, the lab-tested PIL-MeSCL membrane is the more selective towards water vapor.

Table 1. Water vapor and N2, CO2 permeability and selectivity for various polymers at 25 - 35 °C.

Zeolite membranes have been also synthesized and investigated for water vapor removal. The zeolite membranes contain molecular-size pores which provide better separation performance. Other benefits are also their high thermal and chemical stability. A silica- alumina layer was coated on the outer surface of ceramic tubes (ID = 10 mm, thickness = 1 mm, porosity = 50%, average pore size =1 pm) and tested in H2O/N2 separation at 40 - 50 °C, applying vacuum pressure in lumen side and ambient pressure in the shell side. Water vapor permeance was in the range of 12 - 33 GPU andlUO/lSh selectivity was above l,000³¹' ³³. One other possible solution to improve the properties of polymeric membranes would be the incorporation of inorganic fillers into the polymeric matrix, creating mixed matrix membranes (MMMs). However, in both cases, drawbacks including preparation problems (e.g., interfacial defects between the two phases in MMMs) and cost need to be reduced before their industrial use³⁴.

Ionic liquids on a matrix

Another strategy to overcome the drawbacks of polymer, zeolitic and mixed matrix membrane materials, would be the combination of ionic liquids (ILs) with membrane-based technology. The potential of using supported IL membranes (SILMs) in water vapor removal processes was first explored by P. Scovazzo³⁵ and Kudasheva et al.³⁶. P. Scovazzo³⁵ studied H2O permeability through supported polyethylenesulfone (PES) membranes with l-ethyl-3- methylimidazole bis(trifluoromethanesulfonyl)imide ([emimJfTfzN]), l-ethyl-3- methylimidazole dicyanamide ([emim][dca]) and l-ethyl-3 -methylimidazole tetrafluoroborate ([emim][BF4]) and they exhibited H2O permeabilities of 283,000 - 354,000 Barrer. Sullivan-Gonzalez et al.³⁷ evaluated seven different SILMs in CH4 dehydration. Among all, the two ILs l-ethyl-3-methylimidazolium dicyanamide ([emim][dca]) and 1- butyl-3-methylimidazolium nitrate ([bmim][NC>3]) which were immobilized on a polyvinylidene difluoride (PVDF) support, exhibited a water permeance of 3,000 and 2,600 GPU at 80% relative humidity with a H2O/CH4 separation factor of 39,000 and 100,000, respectively. SILMs were also stable and could operate in a wide range of relative humidity for a long period of time^35,37. Recently, encapsulation of ILs in metal-organic framework (MOF) membranes and carbon capsules dispersed in thin polydimethylsiloxane (PDMS) coating layers on a hollow fiber have been also suggested^38,39. Thus, the use of appropriate ionic liquids (ILs) can be a potential solution for the application of membrane-based technology in gas dehydration.

Description of the invention

The invention relates to water vapor removal (dehumidification) with the use of nicotinederived ionic liquids. Membranes prepared from these ionic liquids are used for the removal of water vapor in isothermal processes, including dehumidification of natural gas and biogas, dehumidification of flue gas, removal of water vapor from reactive gas streams, and dehumidification of atmospheric air during ventilation and air conditioning applications and systems.

The disclosed ionic liquid membranes, not only have the best water vapor permeability and selectivity among the ionic liquid membranes reported so far, but also exhibit comparable water vapor separation properties and compare or surpass the respective properties of polymeric membranes. For this reason, the disclosed ionic liquids could be used in various water vapor removal processes (dehumidification, dehydration or drying), as described in the embodiments below. Nicotine-derived ionic liquids for water vapor removal can be defined as salts formed of a cationic species based on the nicotine molecule and an anionic species, with a melting point lower than 100 °C and a negligible vapor pressure close to room temperature. They can also be defined as liquid chemical compounds with a thermal stability up to 300 °C. These ionic liquids have been applied herein as separation technology for water vapor removal from gas streams, such as natural gas, biogas, flue gas and air.

The Nicotine-based ionic liquids for water vapor removal disclosed in the invention, are defined as chemical compounds represented by the general formula (1) where X' is an anion and R is any group of the following: methoxymethyl group, ethoxymethyl group, 2-methoxyethyl group, 2-ethoxyethyl group, octyloxymethyl group, vinyloxyethyl group, benzyloxymethyl group, 2-(trimethylsilyl)ethoxymethyl group, (triisopropylsiloxy)methyl, 2-((t-butyldimethylsilyl)oxy)ethyl group, 3-((t- butyldimethylsilyl)oxy)propyl group, 4-((isopropyldimethylsilyl)oxy)butyl group, 6- ((isopropyldimethylsilyl)oxy)hexyl group, 2-(methoxymethoxy)ethyl group, 2-(2- hydroxyethoxy)ethyl group, 2-(2-methoxyethoxy)ethyl group, 2-(2-(2- hydroxyethoxy)ethoxy)ethyl group, 2-(2-(2-methoxyethoxy)ethoxy)ethyl group, 2- ((tetrahydro-2H-pyran-2-yl)oxy)ethyl group, 3 -((tetrahydro-2H-pyran-2-yl)oxy)propyl group, 6-((tetrahydro-2H-pyran-2-yl)oxy)hexyl group, 2,2-dimethoxyethyl group, 3,3- dimethoxypropyl group, 2, 2-di ethoxy ethyl group, l,l-diethoxypropan-2-yl group, 4,4- dimethoxybutyl group, oxetan-3-yl group, ox etan-3 -ylmethyl group, tetrahydro-2H-pyran- 4-yl group, (tetrahydro-2H-pyran-4-yl)methyl group, (tetrahydrofuran-2-yl)methyl group, (tetrahydrofuran-3-yl)methyl group, (l,3-dioxolan-2-yl)methyl group, (2-methyl-l,3- dioxolan-2-yl)methyl group, (2-methyl-l,3-dioxolan-2-yl)ethyl group, 2-(l,3-dioxolan-2- yl)ethyl group, 3-(l,3-dioxolan-2-yl)propyl group, 4-(l,3-dioxolan-2-yl)butyl group, 2-(l,3- dioxan-2-yl)ethyl group.

Nicotine-derived ionic liquids for water vapor removal can be defined as containing a cationic species mentioned in the previous paragraph in combination with an anionic species. Disclosed anionic species or anions include the: halides (e.g., chloride, bromide, iodide), polyhalides (e.g., pentaiodide, eneaiodide, diiodobromate, dibromoiodate, di odochl orate), borate anions (e.g., tetrafluoroborate, (trifluoromethyl)trifluoroborate, perfluoroethyltrifluoroborate, (heptafluoro-n-propyl)trifluoroborate, (nonafluoro-n- butyl)trifluorobrate, bis(salicylat[2-])borate, tetraphenylborate, triethylammonium-closo- dodecaborate, hexafluorophosphate, perchlorate, nitrate, cyano-based anions (e.g., thiocyanate, dicyanamide, tricyano methanide, tetracyanoborate, dicyanoaurate), metal complex anions (e.g., tetrachloroferrate, tetrachlorocobalt, tetrachloromanganese, hexachlorogadolinium), carboxylate anions (e.g., formate, acetate, (phenylthio)acetate, propionate, benzoate, 2-(methylthio)benzoate, hexanoate, decanoate, lactate, malonate, maleate, levulinate, sec-octylphenoxy acetate, 2-(methylthio)benzoate), fluorocarboxylate anions (e.g., trifluoroacetate, pentafluoropropanoate, heptafluorobutanoate, nonafluoropentanoate, pentadeca fluorooctanoate), sulfonate anions (e.g., hydrogen sulfite, methanesulfonate, ethanesulfonate, dodecylbenzenesulfonate), fluoroalkanesulfonate anions (e.g. trifluoromethanesulfonate, pentafluoroethanesulfonate, 2,2,2-trifluoroehatnesulfonate, heptafluoropropanesulfonate, 2,2,3 -trifluoroethanesulfonate, 2, 2, 3,3,3- pentafluoropropanesulfonate, nonfluorobutanesulfonate, heptadecafluorooctanesulfonate), alkyl sulfate anions (e.g., sulfonate, methyl sulfate, ethyl sulfate, diethyleneglycol monomethylethersulfate), bis(fluoroalkanesulfonyl)imide anions (e g-, bis(trifluoromethanesulfonyl)imide, bis(pentafluoroethanesulfonyl)imide, bis(heptafluoropropanesulfonyl)imide, bis(nonafluorobutanesulfonyl)imide, bis(undecafluoropentanesulfonyl)imide, (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide, trifluoromethanesulfonyl)(heptafluoropropanesulfonyl)imide, (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl) imide, bis(2,2,2- trifluoroethanesulfonyl)imide, (trifluoromethanesulfonyl)(2,2,2-trifluoroethanesulfonyl) imide), bis(fluorosulfonyl)amide anion, tosylate anion, thioacetamide anion, dihexylsulfosuccinate anion, phosphate anions (e.g., dimethyl phosphate, diethyl phosphate, bis(2-ethylhexyl)phosphate, tris(pentafluoroethyl)trifluorophosphate), bis(2,4,4- trimethylpentyl)phosphinate anion, bis(2-ethylhexyl)phosphoric acid anion, anions based on 21 proteinogenic a-amino acids (e.g., glycinate, alaninate, serinate, prolinate). Further examples of the anionic species include saccharinate anion, salycilate anion, thiosalycilate anion, vanillate anion, lauroyl sarcosinate anion, bis(fluorosulfonyl)azanide anion, bis(2- ethylhexyl)di glycol amate anion and phosphotungstate anion.

In some embodiments the anionic species halide, carboxylate and sulfonate anions are preferably used as components of the nicotine-derived ionic liquids for water vapor removal processes.

In one embodiment, the nicotine-based ionic liquids containing the combination of one cation and one anion from those mentioned above are used as a sorbent for selective water vapor absorption from gaseous streams. In another embodiment they are used as a dense layer supported on a porous substrate or they are encapsulated in a substrate forming dense membranes. Suitable substrates can be grouped in two categories, namely, symmetrical or asymmetrical. A symmetrical type of substrate is uniform in composition, structure, and pore size. In contrast, an asymmetrical type of substrate is chemically or physically heterogeneous across its layer. Porous substrates can be polymeric, inorganic, or metallic. In another embodiment, the polymeric materials are from poly(trifluoroethylene), poly(vinylidene chloride), poly(trifluorochloroethylene-co-ethylene) (PTFCE), polyethylene (PE), poly(vinyl fluoride) (PVF), polyvinylalcohol (PVA), polytetrafluoroethylene (PTFE), polypropylene (PP), poly(tetrafluoroethylene-co-ethylene) (ETFE), isobutene-isoprene copolymer (98:2) (Butyl R), butyl rubber, poly(ethylene terephthalate) (PET), crystalline, poly(ethylene-co-vinyl alcohol) (EVOH), polyamide/Nylon 6, poly(vinyl chloride) (PVC), poly(acrylonitrile) (PAN), poly(methacrylonitrile) (PM), gutta percha (GP), methacryl onitrile-styrene butadiene copolymer (88:7:5) (MSB), polyimide (Kapton) (PI), acrylonitrile-styrene copolymer (SAN), neoprene, polystyrene (PS), polycarbonate (PC), polyether-polyurethane (PE-PU), cellulose (Cellophane), polysulfone (PSf), natural rubber (NR), polyethersulfone (PES), sulfonated polyetherketone with Cardo (SPEK-C), poly(ethyl methacrylate) (PEMA), sulfonated poly (ether sulfone) (SPES), poly(phenylene oxide) (PPO), sulfonated poly(amide-imide) (BDSA-40%) (SPAI), poly( 1,3 -butadiene) (PB), cellulose acetate (CA), cellulose nitrate (CN), sulfonated poly(ether ether ketone), ethyl cellulose (EC), poly(ethylene-co-vinyl acetate) (EVA), polyimide 4,40- (hexafluoroisopropylidene) diphthalic anhydride 2,3,5,6-tetramethyl-l,4-phenylenediamine (6FDA-TMPDA), sulfonated poly(ether ether ketone) (SPEEK), polybenzimidazole (PBI), polydimethylsiloxanes (PDMS), poly(ethyleneoxide)-ran-poly(propylene oxide), Nexar, a copolymer of polyethylene oxide and polybutylene terephthalate (IOOOPEO56PBT44), sulfonated polyimides (e.g., NTDA-DMBDSA/BAPF (9/1)), Nafion®. In another embodiment inorganic materials were used, from carbon, silica, zeolite, and various oxides (e.g., AI2O3, TiCE, ZrCE). In a further embodiment zeolites were used, wherein their pores are constructed from aluminium, oxygen, and silicon with alkali or alkaline-earth metals such as sodium, potassium, and magnesium.

In another embodiment, metals forming a porous membrane substrate were used such as palladium, silver, their alloys, and stainless steel. Other metals such as gold, copper, nickel, aluminum, magnesium, titanium, chromium, tungsten, and molybdenum are also used.

Another aspect of the present invention is that the Nicotine-derived ionic liquids are supported or encapsulated in a porous substrate as mentioned above, in the form of flat-sheet, tube or hollow-fibre configuration. Flat-sheet membranes are large sheets, usually on the order of 100 pm thick and they can be packed in modules similar to plate-and-frame heat exchangers. In these modules, counter current flow with the feed and permeate streams in opposite direction, is preferable than co-current flow. Hollow fibres are tubes, typically around 500 pm in diameter, and they can be packed in modules similar to shell -and-tube heat exchanger. The most common flow configuration for these modules is cross-plug flow with the feed stream perpendicular to the permeate stream.

The nicotine-derived ionic liquids disclosed above are ionic liquids showing exceptionally high performance in selective water vapor removal from gas streams. In one embodiment they are used in natural gas (or biogas) dehydration, where water vapor is separated from the constituents of natural gas or biogas.

In another aspect of the invention, the nicotine-derived ionic liquids mentioned are used in removing water vapor from flue gas produced from combustion of carbon (e.g., coal, lignite), natural gas or higher hydrocarbons and oxygen containing organic compounds (e.g., alcohols, phenols, ethers, aldehydes, ketones, carboxylic acids, and esters):

C(s) + O_2(g) CO_2(g) (2)

Separating water vapor from CO2 is very important if CO2 of high purity is needed e.g., in CO2 capture and utilisation processes such as food and beverage industry and chemical production (e.g., methanol, urea).

In another embodiment, nicotine-derived ionic liquids mentioned above can be used in removing water vapor from reformate product gas streams. Steam reforming of natural gas (eq. 5), coal and other hydrocarbons is the main process to produce synthesis gas, a mixture of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2) and steam (H2O). CO2 is produced due to the occurrence of the water - gas shift reaction (eq. 6). Another process for producing synthesis gas is partial oxidation of methane (CH4) with air as an oxidizing agent (eq. 7).

^CH4(_g) + H₂0_(g) CO_(g) + 3H_2Cg) (5)

^C0(g) + H₂0_(g) CO_2(g) + H_2(g) (6)

^CH4(_g) + l/2O_2(g) C0_(g) + 2H_2(g) (7)

H2O has to be separated from the reformate stream to acquire H2 of high purity. In another embodiment, nicotine-based ionic liquids mentioned above are used in these processes.

Another aspect of the invention is the use of the disclosed nicotine-derived ionic liquids for air dehumidification. Separating water vapor from air, thus keeping the relative humidity controlled at desired levels is very important for thermal comfort. In one embodiment, the air is passed over a membrane surface containing nicotine-derived ionic liquids mentioned above at normal pressure. In a preferable embodiment, vacuum can be applied on the opposite side of the membrane to create a driving force for water to permeate through the membrane. The advantages of the disclosed invention are that humid air can be dehumidified without any temperature change and then, the dried air can be cooled down to the thermal comfort level with minimal energy consumption. Finally, nicotine-based ionic liquids mentioned above are used in separation of water vapor contained in a products stream produced in a chemical reaction. Thus, if the chemical reaction is equilibrium limited and water vapor is one of the products of the reaction, removal of water vapor can shift the equilibrium towards the products, leading to higher conversion of the reactants and increase of product yield. An example of such a chemical reaction is the synthesis of dimethyl carbonate from carbon dioxide and methanol:

C0₂ + 2CH₃OH CH₃O)₂C = 0 + 2H₂O (8)

Examples

The invention relates to water vapor removal (dehumidification, dehydration or drying) with the use of nicotine-derived ionic liquids and they are represented with chemical structural formula (1). Representative examples include:

Example 1. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium bromide, [EtOEtNic] [Br]

8 ml (50 mmol) of S-(-)-nicotine and 1.2 eq (60 mmol) of 2-bromoethyl ethyl ether were added in 50 ml of chloroform. The resulting solution was, then, refluxed at 80 °C for 24 hours under stirring, followed by chloroform evaporation at 50 °C under vacuum. The resulting product was washed with diethyl ether to remove unreacted reagents and dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, CDC1₃): 59.33 (d, J=6.0 Hz, 1H), 9.02 (s, 1H), 8.41 (d, J=8.1 Hz, 1H), 7.99 (t, J=7.1 Hz, 1H), 5.02 (t, J=6.7 Hz, 2H), 3.82 (t, J=4.9 Hz, 2H), 3.52 (t, J=8.1 Hz, 1H), 3.33 (q, J=6.9 Hz, 2H), 3.13 (t, J=7.3 Hz, 1H), 2.39-2 31 (m, 1H), 2.25-2.31 (m, 1H), 2.13 (s, 3H), 1.88-1.78 (m, 1H), 1.78-1.70 (m, 1H), 1.61-1.53 (m, 1H), 0.93 (t, J=6.8 Hz, 3H) PPm

¹³C-NMR(151 MHZ, CDCI3): 5 145.02, 144.36, 144.22, 144.04, 127.98, 68.50, 66.87, 66.64, 61.47, 56.54, 40.22, 35.35, 22.96, 14.78 ppm ATR-FTIR: 3417 (H₂O), 3230 (H₂O), 3138 (H₂O), 3000, 2972, 2940, 2874, 2786, 2673, 1633, 1591, 1500, 1473, 1449, 1420, 1378, 1350, 1311, 1292, 1240, 1209, 1155, 1114, 1070, 1045, 1025, 965, 932, 903, 816, 748, 718, 690, 659 cm’¹

Various ionic liquids comprising l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium cation and typical anions were synthesized and examined in combination with membranes for water vapor removal. Representative examples of ionic liquids produced here include:

Example 2. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide, [EtOEtNic] [NTf₂]

0.49 g (8.7 mmol) of potassium hydroxide and 1 eq of l-(2-Ethoxyethyl)-l-methyl-2-(3- pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of ethanol. 2.50 g (8.7 mmol) ofbis(trifluoromethanesulfonyl)imide were also dissolved in 5 ml ethanol under argon atmosphere. Potassium hydroxide solution was, then, mixed with bis(trifluoromethanesulfonyl)imide solution under stirring to form the soluble potassium bis(trifluoromethanesulfonyl)imide salt, followed by adding the remaining l-(2- Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium bromide solution. After half an hour, the resulting solution was centrifugated at 4500 rpm for 20 min to remove the precipitated potassium bromide, followed by ethanol evaporation at 50 °C under vacuum. Finally, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

T l-NMR (600 MHz, DMSO-d₆): 8 9.09 (s, 1H), 8.99 (d, J=4.4 Hz, 1H), 8.67 (br, 1H), 8.18 (t, J=6.3 Hz, 1H), 4.89-4.72 (m, 2H), 3.89-3.81 (br, 2H), 3.53-3.26 (m, 6H), 2.46-2.26 (br, 3H), 2.11-1.86 (br, 3H), 1.01 (t, J=7.0 Hz, 3H) ppm

¹³C-NMR (151 MHz, DMSO-de): 8 145.62, 145.47, 145.25, 145.12, 128.20, 119.74 (q, bis(trifluoromethanesulfonyl)imide anion), 68.22, 67.35, 66.14, 61.17, 56.44, 39.51, 32.90, 22.47, 15.02 ppm

ATR-FTIR (peaks attributed to anion): 1347 (v_a ^ipSO₂), 1328 (v_a ^opSO₂, v_sR, vCC), 1225 (v_aCF₃, vCN), 1176 (v_sR, vNCH_x, v_aCF₃), 1131 (v_sCF₃), 1050 (v_aR, vCC, tNCH_x, v_aSNS), 1036 (v_sR, vNCH_x, vSO, v_s ^ipR), 789 (vCS, 8_aHCCH), 762 (v_sSNS, 8_aHCCH), 739 (8_SCF₃, 5R, NCH_X, 8^ipR, 5_SR,HC-CH), 653 (8_aR, 5SNS), 612 (5_a ^opR, 5SNS, 8_a ^opSO₂), 599 (8_a ^ipSO₂, NCH_X, 8_s ^ipR), 568 (8_aCF₃, 6_aR), 509 (6_aCF₃) cm’¹

Example 3. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium hexafluorophosphate, [EtOEtNic] [PFg]

1.84 g (10.0 mmol) of potassium hexafluorophosphate and 1 eq of 1 -(2 -Ethoxy ethyl)- 1- methyl-2-(3-pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of triple distilled water. After mixing of the two solutions, the mixture was left under stirring overnight. The ionic liquid phase was, then, separated from the aqueous phase and it was washed with triple distilled water until no AgBr precipitate is detected in aqueous phase (droplets of AgNO₃/HNO₃ solution were added in the aqueous phase each time after separation from ionic liquid phase to check for the presence of Br anion). Finally, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, DMSO-d₆): 3 8.93 (s, 1H), 8.89 (d, J=6.0 Hz, 1H), 8.53 (d, J=9.4 Hz, 1H), 8.09 (t, J=6.8 Hz, 1H), 4.77 (t, J=5.0 Hz, 2H), 3.82 (t, J=5.0 Hz, 2H), 3.45-3.39 (m, 3H), 3.17 (t, J=9.5 Hz, 1H), 2.35 (q, J=8.9 Hz, 1H), 2.32-2.25 (m, 1H), 2.15 (s, 3H), 1.93- 1.84 (m, 1H), 1.84-1.76 (m, 1H), 1.67-1.58 (m, 1H), 0.99 (t, J=7.0 Hz, 3H) ppm

¹⁹F-NMR (565 MHz, DMSO-d₆): 8 -70.17 (d, J=711.2 Hz) ppm

³¹P-NMR (243 MHz, DMSO-d₆): 8 -143 86 (hept, J=711.2 Hz) ppm

ATR-FTIR (peaks attributed to anion): 824 (vaPF₆'), 739 (v_sPF₆'), 554 (5PF₆'), 470 (5PF₆ ) cm'¹

Example 4. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium tetrafluoroborate, [EtOEtNic] [BF4]

1.10 g (10.0 mmol) of sodium tetrafluoroborate and 1 eq of l-(2-Ethoxyethyl)-l-methyl-2- (3-pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of triple distilled water. After mixing of the two solutions, the mixture was left under stirring overnight. The ionic liquid phase was, then, separated from the aqueous phase and it was washed with triple distilled water until no AgBr precipitate is detected in the aqueous phase (droplets of AgNO₃/HNO₃ solution were added in the aqueous phase each time after separation from ionic liquid phase to check for the presence of Br anion). Finally, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, DMSO-d₆): 8 8.93 (s, 1H), 8.89 (d, J=6.0 Hz, 1H), 8.54 (d, J=8.0 Hz, 1H), 8.10 (t, J=7.0 Hz, 1H), 4.77 (t, J=4.9 Hz, 2H), 3.82 (t, J=5.0 Hz, 2H), 3.49-3.38 (m, 3H), 3.18 (t, J=8.0 Hz, 1H), 2.36 (q, J=8.7 Hz, 1H), 2.33-2.25 (m, 1H), 2.15 (s, 3H), 1.92- 1.84 (m, 1H), 1.84-1.77 (m, 1H), 1.68-1.58 (m, 1H), 0.99 (t, J=7.0 Hz, 3H) ppm

¹⁹F-NMR (565 MHz, DMSO-d₆): 8 -148.28 (s, ¹⁰BF₄ ), -148.34 (s, “BFF) ppm

ATR-FTIR (peaks attributed to anion): 1044 (vaBFF), 1026 (vaBFF), 764 (VSBFF), 521 (SBFF) cm'¹

Example 5. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium trifluoromethanesulfonate, [EtOEtNic] [TFO]

0.49 g (8.7 mmol) of potassium hydroxide and 1 eq of l-(2-Ethoxyethyl)-l-methyl-2-(3- pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of ethanol. 1.31 g (8.7 mmol) of trifluoromethanesulfonic (triflic) acid were also dissolved in 5 ml ethanol. Potassium hydroxide solution was, then, mixed with 1 -(2 -Ethoxyethyl)- 1 -methyl - 2-(3-pyridinyl)pyrrolidinium bromide under stirring. After half an hour, the solution was centrifugated at 4500 rpm for 20 min to remove the precipitated potassium bromide. Then, the remaining trifluoromethanesulfonic (triflic) acid solution was added in the later solution and left under stirring overnight. After ethanol evaporation at 50 °C under vacuum, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, DMSO-d₆): 8 9.15 (s, 1H), 9.07 (d, J=6.1 Hz, 1H), 8.77 (d, J=8.1 Hz, 1H), 8.26 (t, J=7.2 Hz, 1H), 4.83-4.71 (m, 2H), 4.62 (t, J= 8.6Hz, 1H), 3.91-3.3.80 (m, 3H), 3.48-3.39 (m, 2H), 3.29 (q, J=9.5 Hz, 2H), 2.79 (s, 3H), 2.56-2.50 (m, 1H), 2.33-2.26 (m, 1H), 2.24-2.11 (m, 2H), 1.02 (t, J=7.1 Hz, 3H) ppm

¹³C-NMR (151 MHz, DMSO-d₆): 8 146.56, 146.43, 146.38, 133.84, 128.39, 121.11 (q, CF₃SO₃'), 68.15, 67.99, 66.12, 61.33, 56.40, 39.06, 30.67, 22.09, 15.17 ppm. ¹⁹F-NMR (565 MHz, DMSO-d₆): 5 -77.76 (s, CF₃SO₃ ) ppm

ATR-FTIR (peaks attributed to anion): 1285 (v_aSO₃), 1209 (v_sSO₃), 1159 (v_aCF₃), 1021 (v_sSO₃), 762 (8_SCF₃), 630 (8_sSO₃), 573 (8_aCF₃), 513 (8_aSO₃) cm

Example 6. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium methanesulfonate, [EtOEtNic] [MeSCh]

0.49 g (8.7 mmol) of potassium hydroxide and 1 eq of l-(2-Ethoxyethyl)-l-methyl-2-(3- pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of ethanol. 0.84 g (8.7 mmol) of methanesulfonic acid were also dissolved in 5 ml ethanol. Potassium hydroxide solution was, then, mixed with 1 -(2 -Ethoxy ethyl)- 1 -methyl -2-(3- pyridinyl)pyrrolidinium bromide under stirring. After half an hour, the solution was centrifugated at 4500 rpm for 20 min to remove the precipitated potassium bromide. Then, the remaining methanesulfonic acid solution was added in the later solution and left under stirring overnight. After ethanol evaporation at 50 °C under vacuum, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, DMSO-d₆): 8 9.32 (s, 1H), 9.10 (d, J=5.7 Hz, 1H), 8.86 (d, J=7.7 Hz, 1H), 8.27 (t, J=7.0 Hz, 1H), 4.90-4.82 (m, 1H), 4.82-4.73 (m, 2H), 3.93-3.3.85 (m, 2H), 3.85- 2.29 (m, 1H), 3.44 (q, J=6.6 Hz, 2H), 3.31 (t, J=8.6 Hz, lH), 2.78 (s, 3H), 2.58-2.51 (m, 1H), 2.41 (s, 3H), 2.35-2.29 (m, 1H), 2.25-2.14 (m, 2H), 1.00 (t, J=6.8 Hz, 3H) ppm

¹³C-NMR(151 MHz, DMSO-de): 8 146.60, 146.57 (double intensity), 133.87, 128.37, 68.17, 67.72, 66.06, 61.19, 56.24, 40.11 (CH₃SO₃’), 38.84, 30.76, 21.97, 15.25 ppm

ATR-FTIR (peaks attributed to anion): 1205 (v_aSO₃), 1188 (v_sSO₃), 1155 (v_sSO₃), 1112 (8SOH), 1036 (v_sSO₃), 770 (vC-S, v_sSO₃), 550 (vC-S, 8_sSO₃), 521 (8_aSO₃) cm⁴

Example 7. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium trifluoroacetate, [EtOEtNic] [TFA]

0.49 g (8.7 mmol) of potassium hydroxide and 1 eq of l-(2-Ethoxyethyl)-l-methyl-2-(3- pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of ethanol. 0.99 g (8.7 mmol) of trifluoroacetic acid were also dissolved in 5 ml ethanol. Potassium hydroxide solution was, then, mixed with 1 -(2 -Ethoxy ethyl)- 1 -methyl -2-(3- pyridinyl)pyrrolidinium bromide under stirring. After half an hour, the solution was centrifugated at 4500 rpm for 20 min to remove the precipitated potassium bromide. Then, the remaining trifluoroacetic acid solution was added in the later solution and left under stirring overnight. After ethanol evaporation at 50 °C under vacuum, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, DMSO-d₆): 5 9.29 (s, 1H), 9.09 (d, J=6.0 Hz, 1H), 8.82 (d, J=8. 1 Hz, 1H), 8.25 (t, J=7. 1 Hz, 1H), 4.86-4.75 (m, 2H), 4.71-4.60 (br, 1H), 3.91-3.83 (m, 3H), 3.81- 3.73 (br, 1H), 3.47-3.39 (m, 2H), 3.32-3.19 (br, 1H), 2.77-2.68 (s, 3H), 2.56-2.50 (m, 1H), 2.36-2.26 (br, 1H), 2.21-2.14 (m, 2H), 1.01 (t, J=7.0 Hz, 3H) ppm

¹³C-NMR (151 MHz, DMSO-d₆): 5 159.07 (q, CF₃COO ), 146.45 (three times intensity), 146.37, 128.23, 117.28 (q, CF₃COO ), 68.18, 67.61, 66.05, 61.17, 56.03, 38.80, 31.02, 22.11, 15.14 ppm

¹⁹F-NMR (565 MHz, DMSO-d₆): 5 -73.96 (s, CF₃COO ) ppm

ATR-FTIR (peaks attributed to anion): 1670 (v_aCOO), 1412 (v_sCOO), 1197 (vCF₃), 1168 (vCF₃), 1116 (vCOH), 826 (vCC), 799 (SaOCO), 719 (5_SOCO), 595 (5_s ^ipCF₃), 517 (5_a ^opCF₃) cm'¹

Example 8. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium acetate, [EtOEtNic][Ac]

0.49 g (8.7 mmol) of potassium hydroxide and 1 eq of l-(2-Ethoxyethyl)-l-methyl-2-(3- pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of ethanol. 0.52 g (8.7 mmol) of acetic acid were also dissolved in 5 ml ethanol. Potassium hydroxide solution was, then, mixed with l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium bromide under stirring. After half an hour, the solution was centrifugated at 4500 rpm for 20 min to remove the precipitated potassium bromide. Then, the remaining acetic acid solution was added in the later solution and left under stirring overnight. After ethanol evaporation at 50 °C under vacuum, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows. 'H-NMR (151 MHz, DMSO-d₆): 5 8.99 (br, 2H), 8.55 (d, J=7.5 Hz, 1H), 8.12 (t, J=6.4 Hz, 1H), 4.82 (t, J=4.9 Hz, 2H), 3.83 (t, J=5.5 Hz, 2H), 3.49-3.35 (m, 3H), 3.13 (t, J=7.1 Hz, 1H), 2.40-2.23 (m, 2H), 2.13 (s, 3H), 1.94-1.83 (m, 1H), 1.83-1.77 (m, 1H), 1.73 (s, 3H), 1.67-1.55 (m, 1H), 0.98 (t, J=6.9 Hz, 3H) ppm

¹³C-NMR (151 MHz, DMSO-de): 5 173.73 (CH₃COO ), 144.86 (double intensity), 144.49, 144.25, 128.10, 68.50, 66.99, 66.02, 60.76, 56.73, 40.38, 35.25, 23.66, 23.09 (CH₃COO ), 15.18 ppm

ATR-FTIR (peaks attributed to anion): 1703 (vC=O), 1571 (v_aCOO), 1359 (v_sCOO), 1242 (vC-O), 875 (vCC), 654 (5OCO), 608 (pCOO), 445 (pCOO) cm’¹

Example 9. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium dicyanamide, [EtOEtNic][DCA]

0.89 g (10.0 mmol) of sodium dicyanamide and 1.70 g (10.0 mmol) of silver nitrate were separately dissolved in 10 ml of triple distilled water and mixed under stirring for 10 min in darkness. Aqueous phase was removed, and white solid (sodium dicyanamide) was washed three times with 10 ml of triple distilled water. 1 eq of 1 -(2 -Ethoxy ethyl)- 1 -methyl -2-(3- pyridinyl)pyrrolidinium bromide (Example 1) was dissolved in 10 ml of triple distilled water and sodium dicyanamide obtained was added under stirring in darkness. After 24 h, the solution was filtrated to remove silver bromide and the filtrate was washed three times with 10 ml of di chloromethane. After di chloromethane evaporation at 50 °C under vacuum, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

‘H-NMR (600 MHz, DMSO-d₆): 8 8.93 (s, 1H), 8.89 (d, J=6.1 Hz, 1H), 8.54 (d, J=8.1Hz, 1H), 8.10 (t, J=7.0 Hz, 1H), 4.78 (t, J=4.9 Hz, 2H), 3.83 (t, J=4.9 Hz, 2H), 3.45-3.39 (m, 3H), 3.17 (t, J-7.4 Hz, 1H), 2.35 (q, J=8.8Hz, 1H), 2.32-2.25 (m, 1H), 2.15 (s, 3H), 1.92- 1.84 (m, 1H), 1.84-1.76 (m, 1H), 1.68-1.57 (m, 1H), 0.99 (t, J=7.0 Hz, 3H) ppm

¹³C-NMR (151 MHz, DMSO-ds): 5 144.39, 144.33, 143.87, 143.56, 127.49, 118.98 (N(CN)₂’), 67.96, 66.48, 65.50, 60.31, 56.17, 39.83, 34.71, 22.55, 14.62 ppm

ATR-FTIR (peaks attributed to anion): 2230 (v_aON, v_sCAN), 2193 (v_aON), 2127 (v_sON), 1308 (vaC-N), 902 (v_sC-N), 521 (y_sN-C=N), 511 (y_aN-C=N), 492 (5_aN-C=N) cm’¹ Example 10. Production of l-(2-Ethoxyethyl)-l-methyl-2-(3-pyridinyl)pyrrolidinium tricyano methanide, [EtOEtNic][TCM]

1.13 g (10.0 mmol) of sodium tricyano methanide and 1 eq of 1 -(2 -Ethoxyethyl)- 1-methyl- 2-(3-pyridinyl)pyrrolidinium bromide (Example 1) were separately dissolved in 10 ml of acetonitrile. After mixing of two solutions, the mixture was left under stirring overnight. Then, the solution was centrifugated at 4500 rpm for 20 min to remove the precipitated sodium bromide. After acetonitrile evaporation at 50 °C under vacuum, the product obtained was dried at 50 °C under vacuum for 48 hours. The analytical data of the target product were as follows.

'H-NMR (600 MHz, DMSO-d₆): 8 8.95 (s, 1H), 8.91 (d, J=6.1 Hz, 1H), 8.55 (d, J=7.9Hz, 1H), 8.10 (t, J=7.0 Hz, 1H), 4.78 (t, J=4.9 Hz, 2H), 3.83 (t, J=5.0 Hz, 2H), 3.55-2.45 (br, 1H), 3.42 (q, J=7.0 Hz, 2H), 3.20 (t, J=7.0 Hz, 1H), 2.45-2.35 (br, 1H), 2.35-2.26 (m, 1H), 2.18 (s, 3H), 1.95-1.86 (m, 1H), 1.86-1.77 (m, 1H), 1.73-1.60 (br, 1H), 1.00 (t, J=7.1 Hz, 3H) ppm

¹³C-NMR (151 MHz, DMSO-de): 3 144.40, 143.97, 143.70, 143.68, 127.49, 120.40 (C(CN)₃’), 67.95, 66.51, 65.52, 60.33, 56.14, 39.80, 34.50, 22.50, 14.61, 4.68 (C(CN)₃‘) ppm

ATR-FTIR (peaks attributed to anion): 2154 (v_aON), 1232 (vC-CN, 8(CN)C(CN)), 562 (8CCN) cm’¹

Example 11. Measurement of water vapor permeability and selectivity towards CH4, CO2 and N2 for selected disclosed membranes prepared as supported nicotine-derived ionic liquid.

Nicotine-derived ionic liquids were supported on a hydrophobic flat PVDF substrate (thickness: 125 pm, pore size: 0.22 pm, porosity: 70%) and water vapor permeation properties were determined using the Wicke-Kallenbach method at 30 °C and 1 atm. Supported membranes in the shape of circular discs were placed in a homemade permeation cell. CO2, CH4, N2 or 3% H2O/He gas streams were applied in the retentate side with flow in the range 20-50 cm³ min ¹. In the case of water vapor containing stream, a He flow was passed through a water saturator at 30 °C. Also, the He flow rate in the permeate side was varied in the range 20-100 cm³ min ¹ depending on the magnitude of the flux of the specific membrane and gas combination. The gas composition at the permeate side was analyzed by a gas chromatograph equipped with a flame ionization and a thermal conductivity detector. Measurements of water vapor permeability and selectivity towards CH4, CO2 and N2 for the membranes prepared as supported nicotine-derived ionic liquids are given in Table 2.

Table 2. Water vapor permeability and selectivity towards CH4, CO2 and N2 for various supported nicotine-based ionic liquids membranes at 30 °C and 1 atm compared to Nexar- THF²⁹ polymeric membrane and supported membranes mentioned in the work of Scovazzo³⁵. estimated H2O/CH4 and H2O/N2 selectivities are shown in Table 2.

By changing the type of the anion, water vapor permeability changes in line with the hydrophilicity of the anion. The [EtOEtNic][MeSO₃] ionic liquid exhibits the highest water vapor permeability of 1.46 x 10⁶ Barrer and H2O/N2 selectivity (> 14,600,000) compared to membranes in the literature [29] and [35] (as depicted in Table 2). CH4 and N2 gases are not detected and thus the minimum H2O/CH4 and H2O/N2 selectivities are presented in Table 2. Other ionic liquids such as [EtOEtNic][Ac], [EtOEtNic][DCA] and [EtOEtNic][TfO] also show exceptionally good separation properties. References

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Claims

1. An ionic liquid of the formula wherein X' is an anion and R is any group of the following: methoxymethyl group, ethoxymethyl group, 2-methoxyethyl group, 2-ethoxyethyl group, octyloxymethyl group, vinyloxyethyl group, benzyloxymethyl group, 2-(trimethylsilyl)ethoxymethyl group, (triisopropylsiloxy)methyl, 2-((t-butyldimethylsilyl)oxy)ethyl group, 3-(('t- butyl dimethyl silyl)oxy)propyl group, 4-((isopropyldimethylsilyl)oxy)butyl group, 6- ((isopropyldimethylsilyl)oxy)hexyl group, 2-(methoxymethoxy)ethyl group, 2-(2- hydroxyethoxy)ethyl group, 2-(2-methoxyethoxy)ethyl group, 2-(2-(2- hydroxyethoxy)ethoxy)ethyl group, 2-(2-(2-methoxyethoxy)ethoxy)ethyl group, 2- ((tetrahydro-2H-pyran-2-yl)oxy)ethyl group, 3 -((tetrahydro-2H-pyran-2-yl)oxy)propyl group, 6-((tetrahydro-2H-pyran-2-yl)oxy)hexyl group, 2,2-dimethoxyethyl group, 3,3- dimethoxypropyl group, 2, 2-di ethoxy ethyl group, l,l-diethoxypropan-2-yl group, 4,4- dimethoxybutyl group, ox etan-3 -yl group, oxetan-3-ylmethyl group, tetrahydro-2H-pyran- 4-yl group, (tetrahydro-2H-pyran-4-yl)methyl group, (tetrahydrofuran-2-yl)methyl group, (tetrahydrofuran-3-yl)methyl group, (l,3-dioxolan-2-yl)methyl group, (2-methyl-l,3- dioxolan-2-yl)methyl group, (2-methyl-l,3-dioxolan-2-yl)ethyl group, 2-(l,3-dioxolan-2- yl)ethyl group, 3-(l,3-dioxolan-2-yl)propyl group, 4-(l,3-dioxolan-2-yl)butyl group, 2- (l,3-dioxan-2-yl)ethyl group.

2. An ionic liquid according to claim 1 wherein X" is one of the following anions: chloride, bromide, iodide, pentaiodide, eneaiodide, diiodobromate, dibromoiodate, diodochlorate, tetrafluoroborate, (trifluoromethyl)trifluoroborate, perfluoroethyltrifluoroborate, (heptafluoro-n-propyl)trifluoroborate, (nonafluoro-n-butyl)trifluorobrate, bis(salicylat[2- ])borate, tetraphenylborate, triethylammonium-closo-dodecaborate, hexafluorophosphate, perchlorate, nitrate, thiocyanate, dicyanamide, tricyano methanide, tetracyanoborate, dicyanoaurate, tetrachloroferrate, tetrachlorocobalt, tetrachloromanganese, hexachlorogadolinium, formate, acetate, (phenylthio)acetate, propionate, benzoate, 2- (methylthio)benzoate, hexanoate, decanoate, lactate, malonate, maleate, levulinate, secoctylphenoxy acetate, 2-(methylthio)benzoate), trifluoroacetate, pentafluoropropanoate, heptafluorobutanoate, nonafluoropentanoate, pentadeca fluorooctanoate, hydrogen sulfite, methanesulfonate, ethanesulfonate, dodecylbenzenesulfonate, trifluoromethanesulfonate, pentafluoroethanesulfonate, 2,2,2-trifluoroehatnesulfonate, heptafluoropropanesulfonate, 2,2,3 -trifluoroethanesulfonate, 2, 2, 3, 3,

3 -pentafluoropropanesulfonate, nonfluorobutanesulfonate, heptadecafluorooctanesulfonate), sulfonate, methyl sulfate, ethyl sulfate, di ethyleneglycol monomethylethersulfate), bis(fluoroalkanesulfonyl)imide , bis(trifluoromethanesulfonyl)imide, bis(pentafluoroethanesulfonyl)imide, bis(heptafluoropropanesulfonyl)imide, bis(nonafluorobutanesulfonyl)imide, bis(undecafluoropentanesulfonyl)imide, (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide, trifluoromethanesulfonyl)(heptafluoropropanesulfonyl)imide, (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl) imide, bis(2,2,2- trifluoroethanesulfonyl)imide, (trifluoromethanesulfonyl)(2,2,2-trifluoroethanesulfonyl) imide), bis(fluorosulfonyl)amide anion, tosylate anion, thioacetamide anion, dihexylsulfosuccinate anion, dimethyl phosphate, diethyl phosphate, bis(2- ethylhexyl)phosphate, tris(pentafluoroethyl)trifluorophosphate), bis(2,4,

4- trimethylpentyl)phosphinate anion, bis(2-ethylhexyl)phosphoric acid anion, glycinate, alaninate, serinate, prolinate An ionic liquid according to any of the previous claims wherein the ionic liquid is preferably one of the following compounds: l-(2-ethoxy ethyl)- l-methyl-2-(3- pyridinyl)pyrrolidine methanesulfonate ([EtOEtNic][MeSC>3]), l-(2 -ethoxyethyl)- 1- methyl-2-(3-pyridinyl)pyrrolidine dicyanamide ([EtOEtNic][DMA]), l-(2-ethoxyethyl)-l- methyl-2-(3-pyridinyl)pyrrolidine acetate ([EtOEtNic] [Ac]), l-(2-ethoxyethyl)-l -methyl - 2-(3-pyridinyl)pyrrolidine trifluoroacetate ([EtOEtNic][TFA]). A membrane comprising a layer of the ionic liquid of any of the claims 1 to 3 and a porous substrate, wherein the ionic liquid is placed on the porous substrate.

5. A membrane according to claim 4 wherein the porous substrate is polymeric and preferably poly(trifluoroethylene), poly(vinylidene chloride), poly(trifluorochloroethylene-co-ethylene) (PTFCE), polyethylene (PE), poly(vinyl fluoride) (PVF), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), polypropylene (PP), poly(tetrafluoroethylene-co-ethylene) (ETFE), isobutene-isoprene copolymer (98:2) (Butyl R), butyl rubber, poly(ethylene terephthalate) (PET), crystalline, poly(ethylene-co- vinyl alcohol) (EVOH), polyamide/Nylon 6, poly(vinyl chloride) (PVC), poly(acrylonitrile) (PAN), poly(methacrylonitrile) (PM), gutta percha (GP), methacrylonitrile-styrene butadiene copolymer (88:7:5) (MSB), polyimide (Kapton) (PI), acrylonitrile-styrene copolymer (SAN), neoprene, polystyrene (PS), polycarbonate (PC), polyether-polyurethane (PE-PU), cellulose (Cellophane), polysulfone (PSf), natural rubber (NR), polyethersulfone (PES), sulfonated polyetherketone with Cardo (SPEK-C), poly(ethyl methacrylate) (PEMA), sulfonated poly (ether sulfone) (SPES), poly(phenylene oxide) (PPO), sulfonated poly(amide-imide) (BDSA-40%) (SPAI), poly (1,3 -butadiene) (PB), cellulose acetate (CA), cellulose nitrate (CN), sulfonated poly(ether ether ketone), ethyl cellulose (EC), poly(ethylene-co-vinyl acetate) (EVA), polyimide 4,40- (hexafluoroisopropylidene) diphthalic anhydride 2,3,5,6-tetramethyl-l,4- phenylenediamine (6FDA-TMPDA), sulfonated poly(ether ether ketone) (SPEEK), polybenzimidazole (PBI), polydimethylsiloxanes (PDMS), poly(ethyleneoxide)-ran- poly(propylene oxide), Nexar, a copolymer of polyethylene oxide and polybutylene terephthalate (IOOOPEO56PBT44), sulfonated polyimides.

6. A membrane according to claim 4 wherein the porous substrate comprises carbon, graphite, graphene, SiCh, AI2O3, TiCh, ZrCh, mullite, steel or stainless steel alloys, copper or copper alloys, aluminum or aluminum alloys, titanium or titanium alloys.

7. A membrane according to any of the claims 4 to 6, wherein the membrane has the form of a flat-sheet, or a tube or a hollow-fiber configuration.

8. Use of a membrane described in any of the claims 4 to 7 for the removal of water vapor from a gas or a mixture of gases.

9. Use of a membrane according to claim 8 for the removal of water vapor from natural gas, or from biogas, or from hydrogen, or from flue gas produced from combustion of carbon containing fuel, or from higher hydrocarbons and oxygen containing organic compounds, or from CO2 or from the gases produced during the process of producing synthesis gas from methane or hydrocarbons.

10. Use of a membrane according to claim 8 for air dehumidification.

11. Use of a membrane according to claim 8 for the removal of water vapor from a gaseous product stream produced in a chemical reaction.

12. Process of dehydration of a gas or a mixture of gases comprising passing the gas or the mixture of gases over one or more of the membranes described in the claims 4 to 7 comprising the ionic liquid disclosed in the claims 1 to 3.

13. Process according to the previous claim where the gas or the mixture of gases pass over one or more membranes described in claims 4 to 7 comprising the ionic liquid of claims 1 to 3, from the one side of the membrane the gas or mixture of gases has a flow direction towards the membrane and on the other side of the membrane vacuum is applied.