Ionic liquid mediated valorisation of carbon dioxide

Abstract

The present invention relates to CO2 valorisation into value-added products such as formic acid. In particular, such valorisation is achieved in a reaction media comprising a catalyst and an ionic liquid.

Description

[0001] P7243PC00

[0002] Ionic liquid mediated valorisation of carbon dioxide

[0003] Technical field

[0004] The present invention relates to CO2 valorisation into value-added products such as formic acid. In particular, such valorisation is achieved in a reaction media comprising a catalyst and an ionic liquid.

[0005] Background

[0006] Reducing or halting the still increasing level of atmospheric greenhouse gases (GHGs) such as carbon dioxide (CO2) remains a challenge which occupies most of the industrialised world. Sustainable solutions are particularly sought which allows humanity to continue chemical production using carbon-based feedstocks but without the need for further crude oil extractions. To this end, carbon-capture and utilization (CCU) holds great promise in mitigating atmospheric CO2 levels while at the same time providing a building block for the synthesis of a wide range of industrially relevant chemicals including so-called energy carriers that can reversibly take-up and release hydrogen upon appropriate stimulation.

[0007] Exemplary, formic acid obtained by hydrogenation of CO2 could be used as a liquid organic hydrogen carrier (LOHC) for long-term safe and practical storage of hydrogen.

[0008] L. Piccirilli et al., (2023) employs ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIM-OAc) in combination with various Ru-PNP pincer catalysts and subject to high partial pressures of CO2 and H2 to achieve formic acid via hydrogenation of CO2. The reversible reaction, i.e. dehydrogenation of FA to H2 and CO2 is also exemplified in 1- butyl-3-methylimidazolium acetate (BMIM-OAc).

[0009] The proof-of-concept system disclosed by Piccirilli et al., unfortunately has certain drawbacks, one being the very slow reaction kinetics and yields, achieving only low FA / IL (mol%) yields even after several (+24) hours, and another drawback being the preference for changing catalytic system between hydrogenation and dehydrogenation cycles, hydrogenation being favored in EMIM-OAc, dehydrogenation in BMIM-OAc.

[0010] The present invention sets out to mitigate at least some of the here-above mentioned drawbacks in order to improve the industrial viability of such CO2 conversion systems. P7243PC00

[0011] Summary

[0012] The present invention is directed to methods and systems which can be used to hydrogenate CO2 into value-added products such as formic acid. Formic acid is also in the field known as a liquid organic hydrogen carrier (LOHC) compound and the present invention is also directed at catalytic systems comprising a reaction media in the form of an ionic liquid and a catalyst which can be used in hydrogenation / dehydrogenation cycles of LOHC compounds. Such reactivity and systems find use in combination with fuels cells for production of electricity.

[0013] A first aspect of the present invention is a method for the catalytic hydrogenation of carbon dioxide (CO2) into a value-added product selected from formic acid (FA), methyl formate, methyl propionate and methanol, the method comprising a step of contacting a feed stream comprising CO2 and H2 with a reaction media, wherein the reaction media comprises an ionic liquid (IL) and a ruthenium (Ru)-based pincer complex, further wherein the H2 / CO2 volume ratio in the feed stream is from 50:1 to 1 :1000.

[0014] Within the present invention, the ionic liquid is preferably 1-ethyl-3-methylimidazolium propionate (EMIM-propionate) and the ruthenium-based pincer complex is preferably carbonylchlorohydrido[bis(2-diisopropylphosphinoethyl)amine]ruthenium(ll), which for brevity is referred to as Ru-2 herein.

[0015] Another aspect of the present invention is a catalytic system for reversible hydrogenation and dehydrogenation of a liquid organic hydrogen carrier (LOHC) pair, the system comprising the ionic liquid EMIM-propionate and the transition metal pincer complex Ru(H)(CO)(CI)(iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

[0016] Another aspect of the present invention is use of the catalytic system described above for providing hydrogen to a fuel cell for producing electricity.

[0017] Another aspect of the present invention is also an apparatus for producing electricity comprising a fuel cell and the above described catalytic system, wherein the LOHC pair is FA / CO2. P7243PC00

[0018] Another aspect of the present invention relates to the use of the ionic liquid EMIM- propionate as a media for capture and storage of CO2, such as in carbon capture and storage (CCS). The source of CO2 may be ambient air or up-concentrated streams of CO2, and may be both gaseous or liquid.

[0019] Description of Drawings

[0020] Figure 1 : Hydrogenation screening of EMIM-OAc and EMIM-propionate. Reaction conditions: 10:20 bar (CO2:H2, totalling 30 bars), 1 ml of IL, 420 rpm, 18h with 0.02 mmol Ru-2 at desired temperature. TON numbers correspond to the highest mol% FA / IL values.

[0021] Figure 2: CO2 hydrogenation experiments comparing efficiency of EMIM-OAc and EMIM-propionate with the specified catalyst. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, 18h with 0.02 mmol catalyst at 30 °C. TON numbers correspond to the highest mol% FA / IL values.

[0022] A) carbonyldihydrido[bis(2-diisopropylphosphinoethyl)amine]ruthenium(ll) (Ru-1) employed as hydrogenation catalyst.

[0023] B) carbonylchlorohydrido[bis(2-diisopropylphosphinoethyl)amine]ruthenium(ll), (Ru-2) employed as hydrogenation catalyst.

[0024] Figure 3: Results from screening base additives for CO2 hydrogenation. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of EMIM-OAc, 90 mol% base / IL, 420 rpm, 18h with 0.02 mmol Ru-2 at 30 °C.

[0025] Figure 4: Kinetic study of CO2 hydrogenation in combination with EMIM-propionate and Bronsted acid or non-Bronsted acid additives. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL, 30 mol% additive / IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C.

[0026] Figure 5: Screening CO2 hydrogenation experiments between ionic liquid (IL) and different mol% ratios between Et3N and IL. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, 18h with 0.02 mmol Ru-2 at specified temperature. TON numbers correspond to the highest mol% FA / IL values. P7243PC00

[0027] A) IL = EM IM -form ate; temperature is 30 °C or 50 °C

[0028] B) IL = EMIM-acetate; temperature is 30 °C or 50 °C

[0029] Figure 6: Screening CO2 hydrogenation experiments between EMIM-propionate (IL) and different mol% ratios between Et3N and IL over time. Reaction conditions: 10:20 bar (CC>2:H2), 1 ml of IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C. TON numbers correspond to the highest mol% FA / IL value. Reaction time is 3h, 6h or 18h.

[0030] Figure 7: Hydrogenation experiments between EMIM-propionate and different mol% ratios between MeOH and IL over time. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C. TON numbers correspond to the highest mol% FA / IL value. Reaction time is 3h, 6h or 18h.

[0031] Figure 8: CO2 Hydrogenation experiments between the specified ionic liquid (IL) and different mol% ratios between H2O (neutral additive) and IL over time. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C. TON numbers correspond to the highest mol% FA / IL value.

[0032] A) IL = EMIM-acetate

[0033] B) IL = EMIM-propionate

[0034] Figure 9: CO2 hydrogenation using EMIM-propionate or EMIM-OAc as the ionic liquid in combination with their respective optimized mol% Et3N / IL (base additive). Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C.

[0035] Figure 10: CO2 hydrogenation obtained using the ionic liquid EMIM-propionate with or without initial addition of 30 mol% formic acid (FA). Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL , 30 mol% FA / IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C

[0036] Figure 11 : CO2 hydrogenation experiments utilizing EMIM-OAc as the ionic liquid in combination with a base (Et3N) and / or Bronsted acid (FA) additive. Reaction conditions: 10:20 bar (CO2:H2), 1 ml of IL , 90 mol% Et3N / IL, 30 mol% FA / IL, 420 rpm, with 0.02 mmol Ru-2 at 30 °C.

[0037] Figure 12: FA conversion rate (mol% FA / IL) vs time for the continuous flow of CO2hydrogenation experiment. P7243PC00

[0038] A) Reaction conditions: 1 :5 volume-flow ratio (20 mL / min CO2 and 100 mL / min H2) at 1 bar and 30 °C, with 0.02 mmol of Ru-2 and 1 mL of EMIM-propionate.

[0039] B) Reaction conditions: 1 :5 volume-flow ratio (20 mL / min CO2 and 100 mL / min H2) at 1 bar and 30 °C, with 0.1 mmol of Ru-2 and 1 mL of EMIM-propionate.

[0040] C) Reaction conditions: 1 :10 volume-flow ratio (10 mL / min 20% CO2 and 100 mL / min H2) at 1 bar and 30 °C, with 0.1 mmol of Ru-2 and 1 mL of EMIM-propionate.

[0041] Figure 13: Temperature optimization for formic acid (FA) dehydrogenation batch experiments. Reaction conditions 1 mL of EMIM-propionate, 420 rpm, 0.5 mL of FA.

[0042] A) 0.02 mmol of Ru-2 as catalyst

[0043] B) 0.1 mmol of Ru-2 as catalyst

[0044] Figure 14: GC-TCD analysis of gas feed initially containing 500 ppm CO2 in N2 before and after it has been exposed to EMIM-propionate for 1 hour at 30 °C. The data shows that nearly all CO2 has been removed from the gas feed.

[0045] Figure 15: CO2 hydrogenation yields following sequential CO2 capture and hydrogenation as described in Example 2.2. Reaction conditions for CO2 hydrogenation: 1 :20 bar (CO2:H2), 1 ml of EMIM-propionate, 420 rpm, 18h with 0.02 mmol Ru-2 at 30 °C. TON numbers correspond to the highest mol% FA / IL values.

[0046] Figure 16: Exemplary1H-NMR spectrum (400 MHz, CDCI3) measured on a sample obtained from hydrogenation of CO2 following generalized procedure 1.1 outlined in the Examples, and used in the quantification of hydrogenation yields by evaluating the formate hydrogen peak. Reaction conditions: 1mL EMIM-propionate, 1 :20 bars CO2:H2, 0.02 mmol Ru-2, 420 rpm, 30 °C 18h.

[0047] Figure 17: CO2 absorption over time using EMIM-propionate (1 mL) and a flow of 100 mL / min of imitated air at 30 °C. Gravimetric CO2 / IL ratio (top) and percentage of CO2 trapped from the feed (bottom)

[0048] Figure 18: Total amount of CO2 (mmol) desorbed from 1 mL EMIM-propionate over time using subjected to a flow of 2 mL / min of N2 at different temperatures. From top to bottom, the desorption data represents 100 °C, 80 °C, 60 °C, and 40 °C. P7243PC00

[0049] Detailed description

[0050] To mitigate global warming and in particular the increasing levels of atmospheric CO2, catalytic hydrogenation has been highlighted as one possible solution to reducing CO2 levels.

[0051] The present disclosure provides in one embodiment a method for the catalytic hydrogenation of carbon dioxide (CO2) into formic acid or a chemical derived from reaction with formic acid during said catalytic hydrogenation, the method comprising contacting a feed stream comprising CO2 and H2 with a reaction media, wherein the reaction media comprises an ionic liquid (IL) and a ruthenium (Ru)-based homogeneous catalyst, further wherein the H2 / CO2 volume ratio in the feed stream is from 50: 1 to 1 : 1000.

[0052] Preferably the hydrogenation product is formic acid. In other embodiments, the formic acid may react further to give other products such as methyl formate, methyl propionate and methanol. These products are also preferred as the result of CO2 hydrogenation within the present disclosure.

[0053] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in art to which the subject matter herein belongs. As used herein, the following definitions are supplied to facilitate the understanding of the present invention.

[0054] The term “comprise” is generally used in the sense of include, that is to say permitting the presence of one or more features or components. In addition, as used in the specification and claims, the language "comprising" can include analogous embodiments described in terms of “consisting of” and / or “consisting essentially of”.

[0055] As used in the specification and claims, the term "and / or" used in a phrase such as "A and / or B" herein is intended to include "A and B", "A or B", "A", and "B".

[0056] As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. Similarly, terms such as “one or more” or “at least one” include both the singular and plural form of the respective feature. P7243PC00

[0057] It is a preferred embodiment of the present disclosure that the method for the catalytic hydrogenation of carbon dioxide (CO2) into formic acid or a chemical derived from reaction with formic acid comprises a step of contacting a feed stream comprising CO2 and H2, together or separately, with a reaction media, wherein the reaction media comprises ionic liquid (IL) 1-ethyl-3-methyl-imidazolium propionate (EMIM-propionate) and a ruthenium (Ru)-based homogeneous catalyst, further wherein the H2 / CO2 volume ratio in the feed stream is from 50:1 to 1 : 1000. As used herein, the term ruthenium (Ru)-based homogenous catalyst should be construed as referring to the Ru-pincer complexes described herein. In particular, the Ru-pincer complexes described herein serve to function as catalysts for the valorisation of carbon dioxide into value-added products.

[0058] In one embodiment, the feed steam may be either gaseous or liquid. Most often, feed streams of CO2 will be gaseous, but may exemplary when related to capture and storage of CO2 be liquefied at high pressures. Thus, the feed steam comprising CO2 may also be liquid. In other embodiments, the feed stream will be ambient air.

[0059] “Ambient air” as described herein refers to conventional atmospheric air, also sometimes simply referred to in the public space as outdoor air. In one embodiment, ambient air may comprise approximately 78% nitrogen, 21% oxygen and the remaining 1% being a mixture of carbon oxide(s), nitrogen oxide(s), sulphur oxide(s), helium, argon and methane.

[0060] In one embodiment of the present disclosure, the ionic liquid comprised in the reaction media comprises an imidazolium-based cation and an anion wherein the anion is a Ci- 024 carboxylate, such as C1-C12 carboxylate or Ci-Ce carboxylate, preferably wherein the carboxylate is a monocarboxylate, such as a linear or unbranched monocarboxylate. In one embodiment the ionic liquid anion is Ci-Ce carboxylate, Cl , Br, I, hexafluorophosphate, tetrafluoroborate, trifluoromethanesulfonate, bis(trifluoromethanesulfonimide), C1-C12 dialkylphosphate or hydrogen sulphate.

[0061] In one embodiment, the ionic liquid anion is formate, acetate (OAc), propionate or butanoate. P7243PC00

[0062] Specifically, the ionic liquid is in one embodiment 1-ethyl-3-methylimidazolium formate (EMIM-formate), 1-ethyl-3-methylimidazolium acetate (EM IM -acetate), 1-ethyl-3- methylimidazolium propionate (EMIM-propionate), 1-propyl-3-methylimidazolium formate (PMIM-formate), 1-propyl-3-methylimidazolium acetate (PMIM-acetate), 1- propyl-3-methylimidazolium propionate (PMIM-propionate), 1-butyl-3- methylimidazolium formate (BMIM-formate), 1-butyl-3-methylimidazolium acetate (BMIM-acetate), 1-butyl-3-methylimidazolium propionate (BM I M-propionate), 1 ,3- dimethylimidazolium formate (DMIM-formate), 1,3-dimethylimidazolium acetate (DMIM- acetate), 1 ,3-dimethylimidazolium propionate (DMIM-propionate), or 1 ,3- dimethylimidazolium dimethylphosphate (DMIM-DMP).

[0063] In one embodiment, the ionic liquid is EMIM-propionate, EMIM-acetate or EMIM- formate, preferably EMIM-propionate.

[0064] In one embodiment, the ionic liquid is not EMIM-acetate.

[0065] The hydrogenation method described herein makes use of a homogeneous catalyst. Such types of catalysts are well-known to those skilled in the field.

[0066] A “catalyst” as described herein is a substance that increases the rate of a chemical reaction or reactions without itself undergoing any permanent chemical change.

[0067] A “homogeneous catalyst” as described herein refers to a catalyst that is present, such as dissolved, in the same phase (e.g., liquid or gas) as the ionic liquid phase of the system during catalysis.

[0068] Of particular importance within the present disclosure are homogeneous catalysts in the form of metal complexes comprising a metallic ion ligated by one tridentate ligand and one to three monodentate ligands. The tridentate ligand may be a PNP, CNC, PPP, NNN or NON type tridentate ligand, preferably of the type PNP, such as in pincer ligands which when coordinated in a metal complex results in a pincer complex.

[0069] A “pincer complex” as described herein refers to a transition metal coordination complex with a pincer ligand. Pincer ligands are compounds that coordinate with a metal through three coplanar sites. When the metal is surrounded by six ligation points in octahedral symmetry, this coordination form is also known as meridional coordination geometry. P7243PC00

[0070] In one embodiment of the present disclosure, the pincer complex is of formula (I) wherein,

[0071] M is ruthenium;

[0072] W is an atom selected from the group consisting of P, C, O, and N;

[0073] R1a, R1a’, R1band R1b’ are each independently selected from the group consisting of Ci- Ce alkyl, isopropyl, terf-butyl, a C3-C7 cycloalkyl, a C3-C7 heterocycloalkyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl;

[0074] Z is selected from CO, P(RIH)3, As(RIH)3, isonitrile (CN-R111), NO and N2; and

[0075] X is selected from the group consisting of a hydridoborate, such as tetrahydridoborate (BH4-), a halide, such as F, Cl, Br, or I, a carboxylate, such as formate, acetate or propionate, and H, wherein R111is each individually selected from Ci-Ce alkyl, isopropyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl.

[0076] In one embodiment the pincer complex is of formula (II) P7243PC00 wherein,

[0077] M is ruthenium;

[0078] R1a, R1a’, R1band R1b’ are each independently selected from the group consisting of Ci- Ce alkyl, isopropyl, terf-butyl, a C3-C7 cycloalkyl, a C3-C7 heterocycloalkyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl;

[0079] Z is selected from CO and NO; and

[0080] X is selected from H, BH4, and Cl.

[0081] The term “alkyl” as used herein refers to a linear or branched hydrocarbon moiety

[0082] The term "alkoxy" as used herein refers to a group of formula -O- alkyl, wherein alkyl is defined as above. In particular, C1-C3 -alkoxy is intended to indicate such hydrocarbon having 1 , 2 or 3 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, and isopropoxy.

[0083] As used herein the term “cycloalkyl” refers to a monocyclic or polycyclic system. The term “cycloalkyl” as used herein can optionally contain one or more unsaturations or substituents. The term “heterocycloalkyl” refers to monocyclic or polycyclic systems where at least one of the ring atoms are heteroatoms(s). Examples of heteroatoms include N, O, S, As, B or P.

[0084] The term "aryl" refers to a cyclic or polycyclic moiety having a conjugated unsaturated (4n+2)TT electron system (where n is a positive integer), sometimes referred to as a delocalized TT electron system. The term “heteroaryl” refers to aryl moieties wherein at least one of the ring atoms are heteroatom(s).

[0085] In one embodiment of formula (II), R1a, R1a’, R1band R1b’ are each independently selected as phenyl or isopropyl, each of which may optionally be substituted by one or more selected from halogen, cyano, amino, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5- C10 aryl. P7243PC00

[0086] In one embodiment of formula (II), R1a, R1a’, R1band R1b’ are each independently selected as phenyl or isopropyl. In another embodiment R1a, R1a’, R1band R1b’ are all selected as either phenyl or isopropyl.

[0087] In one embodiment of formula (II), Z is CO and X is H. In another embodiment, Z is CO and X is Cl. In another embodiment, Z is CO and X is BH4.

[0088] In one embodiment, the pincer complex is of formula (III) wherein X is Cl or H.

[0089] In one embodiment of the present disclosure, the pincer complex is Ru(H)2(CO)(iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

[0090] In one embodiment of the present disclosure, the pincer complex is of formula (IV)

[0091] In one embodiment of the present disclosure, the pincer complex is Ru(H)(CO)(CI)(iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

[0092] In one embodiment, the pincer complex is of formula (V) P7243PC00 formula (V)

[0093] Within the present disclosure it is understood that the pincer complex has the function of a catalyst, such as a homogeneous catalyst when used in relation to CO2hydrogenation.

[0094] In one embodiment of the present disclosure, the catalyst is present in an amount between 0.01% and 5% (w / w) based on weight of the ionic liquid. Preferably, the catalyst is present in an amount between 0.1% and 1.0% (w / w) based on weight of the ionic liquid, such as between 0.1% and 0.2% (w / w), 0.2% and 0.3% (w / w), 0.3% and 0.4% (w / w), 0.4% and 0.5% (w / w), 0.5% and 0.6% (w / w), 0.6% and 0.7% (w / w), 0.7% and 0.8% (w / w), 0.8% and 0.9% (w / w) or 0.9% and 1.0% (w / w). In one embodiment, the catalyst is present in an amount between 1.0% and 5.0% (w / w) based on weight of the ionic liquid such as between 1.0% and 1.2% (w / w), 1.2% and 1.5% (w / w), 1.5% and 1.8% (w / w), 1.8% and 2.2% (w / w), 2.2% and 2.6% (w / w), 2.6% and 3.0% (w / w), 3.0% and 3.8% (w / w), 3.8% and 4.5% (w / w) or 4.5% and 5.0% (w / w).

[0095] In one embodiment of the present disclosure, the catalyst is present in an amount between 0.01% and 5% (mol%) based on the amount of the ionic liquid. Preferably, the catalyst is present in an amount between 0.1% and 1.0% (mol%) based on weight of the ionic liquid, such as between 0.1% and 0.2% (mol%), 0.2% and 0.3% (mol%), 0.3% and 0.4% (mol%), 0.4% and 0.5% (mol%), 0.5% and 0.6% (mol%), 0.6% and 0.7% (mol%), 0.7% and 0.8% (mol%), 0.8% and 0.9% (mol%) or 0.9% and 1.0% (mol%). In one embodiment, the catalyst is present in an amount between 1.0% and 5.0% (mol%) based on weight of the ionic liquid such as between 1.0% and 1.2% (mol%), 1.2% and 1.5% (mol%), 1.5% and 1.8% (mol%), 1.8% and 2.2% (mol%), 2.2% and 2.6% (mol%), 2.6% and 3.0% (mol%), 3.0% and 3.8% (mol%), 3.8% and 4.5% (mol%) or 4.5% and 5.0% (mol%).

[0096] In one embodiment of the present disclosure, the ionic liquid is EMIM-propionate and the catalyst is present in an amount between 0.01% and 5.0% (mol%) based on the P7243PC00 amount of the EMIM-propionate, such as between 0.1% and 2.5% (mol%), such as between 1.0% and 2.5% (mol%) based on the amount of the EMIM-propionate, such as preferably wherein the catalyst is of formula (V).

[0097] In one embodiment of the present disclosure, the ionic liquid is EMIM-acetate and the catalyst is present in an amount between 0.01% and 5.0% (mol%) based on the amount of the EMIM-acetate, such as between 0.1% and 2.5% (mol%), such as between 1.0% and 2.5% (mol%) based on the amount of the EMIM-acetate, such as preferably wherein the catalyst is of formula (V).

[0098] In one embodiment of the present disclosure, the ionic liquids described herein can be combined with solid porous materials, leading to heterogeneous supported ionic liquid systems, in which the Pincer-type catalyst is dissolved in the ionic liquid that resides in the pores of the solid material.

[0099] Such systems are commonly referred to as SILP (Supported Ionic Liquid Phase) materials. The supports implemented in SILP materials are similar to, or the same, materials as typically used as support materials for heterogeneous catalysts, such as organic polymers (examples can be polystyrene-, divinylbenzene-, PEG-based polymers), alumina, titania, silica, carbon, MgO, ceria, zirconia, or mixed oxides, such as MgAI spinel, ZrCe oxides. One embodiment of the present disclosure thereby combines an ionic liquid, a homogeneous catalyst and a solid porous support in order to arrive at a SILP catalyst, which can be directly implemented in the catalytic hydrogenation of CO2 into value-added chemicals such as formic acid.

[0100] In one embodiment, the SILP catalyst comprises EMIM-propionate, EMIM-acetate, EMIM-formate or EMIM-butanoate as the ionic liquid.

[0101] In one embodiment, the SILP catalyst comprises any one of the catalysts described herein as Ru-2 or Ru-1. In one embodiment, the catalyst may be provided in an amount corresponding to from 0.1 wt% to 10 wt% of the porous solid material, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 2.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10 wt% or any 0.1 wt% incremental value therein between. P7243PC00

[0102] In one embodiment, the SILP catalyst comprises a porous solid material having a pore volume of 0.20 cm3 / g to 5.00 cm3 / g, such as 0.20 cm3 / g to 0.25 cm3 / g, such as 0.25 cm3 / g to 0.30 cm3 / g, such as 0.30 cm3 / g to 0.35 cm3 / g, such as 0.35 cm3 / g to 0.40 cm3 / g, such as 0.40 cm3 / g to 0.45 cm3 / g, such as 0.45 cm3 / g to 0.50 cm3 / g, such as 0.50 cm3 / g to 0.55 cm3 / g, such as 0.55 cm3 / g to 0.60 cm3 / g, such as 0.60 cm3 / g to 0.65 cm3 / g, such as 0.65 cm3 / g to 0.70 cm3 / g, such as 0.70 cm3 / g to 0.75 cm3 / g, such as 0.75 cm3 / g to 0.80 cm3 / g, such as 0.80 cm3 / g to 0.85 cm3 / g, such as 0.85 cm3 / g to 0.90 cm3 / g, such as 0.90 cm3 / g to 0.95 cm3 / g, such as 0.95 cm3 / g to 1.00 cm3 / g, such as 1.00 cm3 / g to 1.20 cm3 / g, such as 1.20 cm3 / g to 1.40 cm3 / g, such as 1.40 cm3 / g to 1.60 cm3 / g, such as 1.60 cm3 / g to 1.80 cm3 / g, such as 1.80 cm3 / g to 2.00 cm3 / g, such as 2.00 cm3 / g to 2.50 cm3 / g, such as 2.50 cm3 / g to 3.00 cm3 / g, such as 3.00 cm3 / g to 4.00 cm3 / g, such as 4.00 cm3 / g to 5.00 cm3 / g or any 0.05 cm3 / g incremental value therein between. The pore volume may in one embodiment be determined via N2-physisoprtion as routinely done in the art.

[0103] In one embodiment, the SILP catalyst comprises a porous solid material having a pore volume of 0.20 cm3 / g to 1 .00 cm3 / g, such as 0.20 cm3 / g to 0.25 cm3 / g, such as 0.25 cm3 / g to 0.30 cm3 / g, such as 0.30 cm3 / g to 0.35 cm3 / g, such as 0.35 cm3 / g to 0.40 cm3 / g, such as 0.40 cm3 / g to 0.45 cm3 / g, such as 0.45 cm3 / g to 0.50 cm3 / g, such as 0.50 cm3 / g to 0.55 cm3 / g, such as 0.55 cm3 / g to 0.60 cm3 / g, such as 0.60 cm3 / g to 0.65 cm3 / g, such as 0.65 cm3 / g to 0.70 cm3 / g, such as 0.70 cm3 / g to 0.75 cm3 / g, such as 0.75 cm3 / g to 0.80 cm3 / g, such as 0.80 cm3 / g to 0.85 cm3 / g, such as 0.85 cm3 / g to 0.90 cm3 / g, such as 0.90 cm3 / g to 0.95 cm3 / g, such as 0.95 cm3 / g to 1.00 cm3 / g or any 0.05 cm3 / g incremental value therein between.

[0104] In one embodiment, the SILP catalyst comprises a porous solid material characterized by being mesoporous. In one embodiment, the SILP catalyst comprises a porous solid material characterized by an average pore diameter of 2 nm to 50 nm, such as from 2 nm to 4 nm, such as from 4 nm to 6 nm, such as from 6 nm to 8 nm, such as from 8 nm to 10 nm, such as from 10 nm to 15 nm, such as from 15 nm to 20 nm, such as from 20 nm to 25 nm, such as from 25 nm to 30 nm, such as from 30 nm to 35 nm, such as from 35 nm to 40 nm, such as from 40 nm to 45 nm, such as from 45 nm to 50 nm or any 1.0 nm incremental value therein between. P7243PC00

[0105] In one embodiment, the SILP catalyst comprises a porous solid material having a surface area of 70 m2 / g to 300 m2 / g, such as 70 m2 / g to 85 m2 / g, such as 85 m2 / g to 100 m2 / g, such as 100 m2 / g to 120 m2 / g, such as 120 m2 / g to 150 m2 / g, such as 150 m2 / g to 160 m2 / g, such as 160 m2 / g to 170 m2 / g, such as 170 m2 / g to 190 m2 / g, such as 190 m2 / g to 220 m2 / g, such as 220 m2 / g to 250 m2 / g, such as 250 m2 / g to 275 m2 / g, such as 275 m2 / g to 300 m2 / g or any 5 m2 / g incremental value therein between. The surface area may in one embodiment be determined via BET analysis as is commonly performed in the art. Such surface areas are also referred to as BET surface areas.

[0106] As used herein, unless otherwise specified, surface area refers to BET surface area and pore volume refers to pore volume as determined by N2-physisoprtion at -196 °C.

[0107] In one embodiment, the porous solid material is alumina, titania, silica, carbon, MgO, ceria, zirconia, or mixed oxides, such as MgAI spinel and ZrCe oxides.

[0108] In one embodiment, the SILP catalyst comprises EMIM-propionate, Ru-2 and silica, wherein the silica has a pore volume of 0.55(5) cm3 / g and a surface area of 160(5) m2 / g.

[0109] The working conditions (temperature, gas pressures) are overall the same as for the homogeneous liquid solution. The SILP catalysts are typically used for continuous- flow gas-phase reactions with the catalyst-containing SILP residing in a fixed, or fluidized, bed reactor, and may in one embodiment optionally be subjected to pressures in the range of 1 to 100 bars of each of CO2 and H2 if desired, more preferably 5-50 bars, IQ- 50 bars, 10-30 bars, or 5-10 bars of each of CO2 and H2 if desired.

[0110] The SILP catalysts of the present disclosure may advantageously be prepared by combining the Ru-2 catalyst with the relevant ionic liquid and porous solid material (support) in a low-boiling solvent, preferably a non-coordinating solvent, which can easily be removed later by simple evaporation, optionally under a vacuum. In one embodiment, the low-boiling solvent is acetone, methanol, acetonitrile, chloroform or dichloromethane. Preferably, the low-boiling non-coordinating solvent is a chlorinated alkane, such as dichloromethane or chloroform, preferably dichloromethane also commonly referred to as DCM. P7243PC00

[0111] In one embodiment of the present disclosure, the feed stream used for the described hydrogenation method comprises essentially of CO2 and H2, provided together or separately. That is to say, the method may make use of two separate feed streams, one dedicated for CO2 and another dedicated for H2.

[0112] In one embodiment of the present disclosure, the feed stream comprises CO2 in a concentration from 1.000 ppm to 500.000 ppm, such as from 10.000 ppm to 200.000 ppm. In one embodiment of the present disclosure, the feed stream comprises CO2 in a concentration of less than 50.000 ppm, such as less than 5.000 ppm, such as less than 1.000 ppm, such as in a concentration from 200 to 1 .000 ppm. In one embodiment of the present disclosure, the feed stream comprises CO2 in a concentration of 200 ppm to 400 ppm, 400 ppm to 600 ppm, 600 ppm to 1.000 ppm, 1.000 ppm to 2.000 ppm, 2.000 ppm to 4.000 ppm, 4.000 ppm to 6.000 ppm or 6.000 ppm to 10.000 ppm. In one embodiment of the present disclosure, the feed stream is atmospheric air or imitated air comprising 400 ppm to 500 ppm CO2, such as approximately 450 ppm CO2, such as approximately 420 ppm CO2.

[0113] In one embodiment of the present disclosure, the CO2 feed stream is provided at a pressure between 1 and 40 bar, such as between 1 and 15 bar. In one embodiment, the CO2 feed stream is provided at a pressure of 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 bar.

[0114] In one embodiment of the present disclosure, the hydrogen feed stream is provided at a pressure between 1 and 40 bar, such as between 1 and 20 bar. In one embodiment, the H2 feed stream is provided at a pressure of 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19 or 20 bar. In some embodiments, the hydrogen feed stream is provided at a pressure between 20 and 40 bars such as between 28-32 bars, preferably 30 bars.

[0115] In one embodiment of the present disclosure, the H2 / CO2 ratio as provided by the feed stream is from 50:1 to 1 :1000. In one embodiment, the H2 / CO2 ratio 20:1 , 15:1 , 10:1 , 5:1 , 4:1 , 3:1 , 2:1 , 1 :1 , 1 :2, 1 :5, 1 :10 or 1 :20. In one embodiment, the H2 / CO2 ratio is 1 :300, 1 :400, 1 :500 or 1 :1000. 1 :1000 is approximately the same H2 / CO2 ratio as found in ambient air. P7243PC00

[0116] In one embodiment of the present disclosure, the H2 / CO2 ratio is 20:1. In one embodiment of the present disclosure, the H2 / CO2 ratio is 5:1. In one embodiment of the present disclosure, the H2 / CO2 ratio is 1 :1.

[0117] In one embodiment of the present disclosure, the method is conducted under ambient pressure and / or temperature. In one embodiment, the feed stream is ambient air.

[0118] In one embodiment of the present disclosure, the feed stream is provided at a total pressure between 1 and 200 bar, such as between 1 and 40 bar, such as between 1 and 20 bar. Total pressure as used herein refers to the accumulation of all partial pressures of the gaseous species comprised in the feed stream.

[0119] In one embodiment of the present disclosure, the hydrogenation method is carried out at temperature between 25 °C and 200 °C, such as at 25 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C or 200 °C.

[0120] In one embodiment of the present disclosure, the hydrogenation is carried out at 30(±5) °C, such as 30 °C. In another embodiment, the hydrogenation is carried out at temperature between 50(±5) °C, such as 50 °C.

[0121] It has been found that the CO2 hydrogenation into formic acid by the ionic liquid / catalyst pairs described herein can be greatly influenced by addition of certain compounds into the reaction mixture, also referred to herein as additives. The hydrogenation may be affected both such that the total yield of formic acid is increased and / or such that the rate at which formic acid is produced is accelerated.

[0122] One embodiment of the present disclosure thus comprise the hydrogenation method described herein and further comprising the addition of at least one additive in an amount which increases at least one of: i) formic acid yield; and / or ii) formic acid production rate, as compared to without addition of said additive under the same reaction conditions. It is preferred that the reaction conditions for the additive / non-additive comparison is at least 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, 18h with 0.02 mmol catalyst at 30 °C. P7243PC00

[0123] In one embodiment of the present disclosure, the at least one additive is a Bronsted acid.

[0124] In one embodiment of the present disclosure, the at least one additive is a base, with the proviso that the base is not trioctylamine, preferably wherein the at least one base is a C3-15 alkylamine, preferably a secondary or tertiary C3-15 alkylamine.

[0125] In one embodiment of the present disclosure, the at least one additive is selected from H3PO4, formic acid, ethanoic acid, propionic acid, dibutylamine, diethylamine, dipropylamine, tributylamine, triethylamine, propylamine, tripropylamine, N,N- diethylethylenediamine, water, methanol, and ethanol.

[0126] In one embodiment of the present disclosure, the at least one additive is selected from H3PO4, formic acid, propionic acid, dipropylamine, and triethylamine.

[0127] In one embodiment of the present disclosure, the at least one additive is a mixture of a Bronsted acid and a base, such as a mixture of formic acid and triethylamine.

[0128] In one embodiment of the present disclosure, the additive is added in an amount ranging from 1 mol% to 300 mol% based on the amount of ionic liquid.

[0129] In one embodiment of the present disclosure, the additive is added in an amount ranging from 1 mol% to 300 mol%, such as from 1 mol% to 2 mol%, such as from 2 mol% to 3 mol%, such as from 3 mol% to 5 mol%, such as from 5 mol% to 10 mol%, such as from 10 mol% to 20 mol%, such as from 20 mol% to 30 mol%, such as from 30 mol% to 50 mol%, such as from 50 mol% to 60 mol%, such as from 60 mol% to 70 mol%, such as from 70 mol% to 80 mol%, such as from 80 mol% to 90 mol%, such as from 90 mol% to 100 mol%, such as from 100 mol% to 120 mol%, such as from 120 mol% to 150 mol%, such as from 150 mol% to 200 mol%, such as from 200 mol% to 250 mol%, such as from 250 mol% to 300 mol%, based on the amount of ionic liquid.

[0130] In one embodiment of the present disclosure, the additive is triethylamine and is added in an amount ranging from 80 mol% to 90 mol% based on the amount of ionic liquid. P7243PC00

[0131] In one embodiment of the present disclosure, the ionic liquid is EM IM -acetate and the additive is triethylamine, preferably in an amount corresponding to 33 mol% to 125 mol%, more preferably 90 mol% triethylamine based on the amount of EMIM-acetate.

[0132] In one embodiment of the present disclosure, the ionic liquid is EMIM-propionate and the additive is triethylamine, preferably 3 mol% to 80 mol%, more preferably 50 mol% triethylamine based on the amount of EMIM-propionate.

[0133] In one embodiment of the present disclosure, the ionic liquid is EMIM-propionate and the additive is methanol, preferably 10 mol% to 50 mol% methanol based on the amount of EMIM-propionate.

[0134] In one embodiment of the present disclosure, the at least one additive is water. In other embodiments, and although the broad applicability of the described method means that it can be applied in non-anhydrous conditions, the at least one additive is preferably not water.

[0135] The present disclosure also provides in one embodiment, the use of a reaction media comprising 1-ethyl-3-methylimidazolium propionate (EMIM-propionate) and homogeneous catalyst Ru(H)(CO)(CI)(iPrPNP) for hydrogenation of CO2 into formic acid (FA).

[0136] In one embodiment of the use, the reaction media may optionally not comprise water, and / or may optionally further comprise a Bronsted acid and / or Bronsted base.

[0137] The present disclosure also provides a method which has implications for hydrogen storage and energy, in particular related to fuel cells. In hydrogen fuel cells, energy is liberated by electrochemical reaction between hydrogen and oxygen to create water and electrical energy. Herein, hydrogen is supplied to the anode side where it is catalytically split by the anode into protons and electrons. The protons migrate to the cathode side where they react with a stream of oxygen also provided at the cathode side.

[0138] However, for the stable operation of hydrogen fuel cells, hydrogen storage is of paramount importance and presents a major technical challenge. Liquid organic compounds that can be used to store hydrogen are generally referred to as Liquid Organic Hydrogen Carriers (LOHCs). These are unsaturated organic compounds that P7243PC00 can store useful amounts of hydrogen. These LOHCs are hydrogenated for storage and dehydrogenated again when the hydrogen is needed, e.g. for a fuel cell.

[0139] The functioning of an LOHC is described as follows. The low-energy form of the LOHC is reversibly converted by means of hydrogenation by hydrogen into the energy-rich form, which, in a reverse reaction, recovers hydrogen from the hydrogenated product with the formation of the low-energy form merely by a temperature increase and / or reduction of the hydrogen pressure. The reaction is therefore reversible. Reversible means, that the materials undergo cyclic transformation from a low-energy dehydrogenated state to an energy-rich hydrogenated state and back to the dehydrogenation state, without a significant loss of the LOHC material. In an optimal case, these cycles can be repeated indefinitely even on a continuous basis. In practice, both the hydrogenation and dehydrogenation reaction require a catalyst. The hydrogenation and dehydrogenation reactions can be done in different locations, and in this way the LOHC materials provide a method to transport energy in the form of hydrogen, without any loss or consumption of the LOHC materials. Particularly, advantageously usable LOHCs allow this reversible conversion under technically relevant conditions, pressure and temperature being mentioned by way of example. Within the present inventions, the LOHC system is preferably CO2 / formic acid, with formic acid representing the high-energy form of the LOHC.

[0140] One embodiment of the present disclosure is thus a catalytic system for reversible hydrogenation and dehydrogenation of a liquid organic hydrogen carrier (LOHC) pair, the system comprising the ionic liquid EMIM-propionate and the transition metal pincer complex Ru(H)(CO)(CI)(iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine). In a preferred embodiment, the LOHC pair is FA / CO2.

[0141] Within the scope of the present invention is also an embodiment directed to use of the catalytic system described herein above for providing hydrogen to a fuel cell for producing electricity. The present disclosure also encompasses in one embodiment an apparatus for producing electricity comprising a fuel cell and the catalytic system as described herein above.

[0142] It has also been surprisingly found that the ionic liquid EMIM-propionate functions as a potent scavenger of CO2, and may found use in CO2 capture and storage processes. P7243PC00

[0143] As evident from Example 2, EMIM-propionate potentially removes more than 95% of gaseous carbon dioxide from ambient air in a relatively short time span of 1 hour. The present disclosure thereby encompasses in one embodiment the use of EMIM- propionate as a media for capture of CO2, such as in carbon capture and storage (CCS) processes.

[0144] In one embodiment of the present disclosure related to capture of CO2, it is preferred that the CO2 is captured from an atmospheric source, and may optionally be under ambient pressure and / or temperature. More preferably, the source comprises CO2 in a concentration of less than 5.000 ppm, more preferably in the range of 200 ppm to 1.000 ppm.

[0145] The present invention will now be described in more detail by the presented examples here below. It would be understood by any person skilled in the art that the below examples are not to be considered as limiting on the scope and applicability of the described method and only serves for illustrative purposes of the broadly applicable nature of the described method.

[0146] Examples

[0147] Carbonyldihydrido[bis(2-diisopropylphosphinoethyl)amine]ruthenium(ll), was synthesized as described below. For brevity, this Ru-complex is referred to herein as Ru-1.

[0148] Commercial carbonylchlorohydrido[bis(2- diisopropylphosphinoethyl)amine]ruthenium(ll) (CAS 1311164-69-8) with a purity > 97% was obtained from STREM chemicals. For brevity, this Ru-complex is referred to herein as Ru-2. 1-ethyl-3-methylimidazolium methylcarbonate was bought from IOLITEC >97% purity, 30% in MeOH (CAS 251102-25-7).

[0149] Unless specifically stated otherwise, all other chemicals employed were bought from Merck, with purities >97% and used as received.

[0150] Synthesis of Ru-1

[0151] In a round-bottom flask, 50 mg (54.47 pmol) of Ru[CO(PPh3)3(H)2] was mixed with 54.47 pmol (1 equivalent) of the PNP-ligand bis[(2-diisopropylphosphino)ethyl]amine dissolved in THF. The reaction mixture was stirred for 3 hours. After this period, a dark P7243PC00 gold solution was observed which by the addition of pentane causes a crude product to precipitate out.

[0152] The crude product was washed with a 1 :2 volume ratio of THF to pentane to remove any remaining PNP ligand. The resulting white powder precipitate, corresponding to Ru-1 , was then filtered. A recrystallization process was performed with pentane.

[0153] All manipulations were carried out under inert atmosphere. The intended product was verified by NMR analysis. Purity was verified by31P NMR spectroscopy (162 MHz, CeDerevealing a single signal at 93 ppm.

[0154] Synthesis of Ionic liquids

[0155] All of the EMIM ionic liquids were synthetised via an anion exchange methodology employing 1-ethyl-3-methylimidazolium methylcarbonate as a substrate.

[0156] In a two-neck flask, connected to a bubbler, the desired amount of 1 -ethyl-3- methylimidazolium methylcarbonate (30% in MeOH) was mixed dropwise with the desired counter anion in its acid form, (propionic acid for the purpose of obtaining EMIM propionate etc.), in a 1 :1 molar ratio mixture at room temperature for 5 hours under a gentle argon flow to facilitate the release of the vigorous gas formation. Subsequently, the ionic liquid was dried under vacuum for 3 days to remove all traces of methanol. A light-gold viscous ionic liquid was obtained as the desired product.

[0157] The above general procedure was employed for the successful synthesis of the ionic liquids EMIM-propionate, EMIM-formate, EMIM-acetate and EMIM-butanoate.

[0158] Evaluation of CO2 hydrogenation and formic acid dehydrogenation yields

[0159] Yields were evaluated based on1H-NMR spectra. In a characteristic1H-NMR (400 MHz, CDCI3) of a sample obtained from a hydrogenation experiment of CO2 to formic acid (FA), the spectrum will usually comprise at least 7 signals corresponding to EMIM- propionate: 1.06 (t, 3H, CH3, anion), 2.27 (q, 2H, CH2, anion), 1.53 (t, 3H, CH3, cation), 4.01 (s, 3H, CH3, cation), 4.32 (q, 2H, CH2, cation), 7.34 (d, 2H, CH, CH, cation) and 10.85 (s, 1 H, CH, cation). If the hydrogenation is successful an additional signal at 8.6 (s, 1 H, HCOO) will appear corresponding to the formate proton in formic acid. In order to quantify the conversion yield, the signal of the EMIM-methyl group at approximately 4.0 ppm is set as reference (3H). The conversion of CO2 into formic acid expressed as a formic acid yield corresponds to the integrated area of the peak corresponding to the carbon-bonded hydrogen of formic acid, located at approximately 8.6 ppm. Illustrated in P7243PC00

[0160] Fig. 16, this area is 0.60 (reference peak is 3.00) corresponding to a yield of 60 mol% FA / IL.

[0161] For experiments where an additive is included in the reaction mixture, the analysis and quantification of yield does not change as the yield is only dependent on the area of the formate hydrogen peak relative to the hydrogen peak of the methyl group of the EMIM cation reference peak.

[0162] For experiments where formic acid (FA) was used as the additive, a baseline1H NMR spectrum was first obtained from a sample obtained by adding FA before the hydrogenation reaction took place. The resulting formate peak was integrated to establish the initial amount of FA. After the completed hydrogenation reaction, the formate peak of a post-reaction sample was re-integrated, and the integrated area corresponding to the original amount of FA added (exemplary 30 mol% FA / IL) was subtracted from this integration, such as in a conventional baseline correction. This methodology was used for all data points obtained from samples where FA was acting as an additive.

[0163] By the same methodology, the degree of dehydrogenation starting from formic acid can be evaluated by evaluating the decrease in the1H-NMR signal (400 MHz, CD3CN) at approximately 8.6 (s, 1H, HCOO) corresponding to a consumption of formic acid. If the dehydrogenation of formic acid into CO2 is successful, the formate hydrogen peak decrease to an extent corresponding to the consumption of FA. In order to quantify the conversion, the signal of the methyl group of the EMIM cation at approximately 4.0 ppm is set as reference (3H). The consumption of formic acid corresponds to the decrease of the integration of its respectively formate hydrogen peak at 8.6 ppm until this signal does not decrease anymore, typically when it is not observable anymore.

[0164] For experiments using EMIM-formate or EMIM-acetate as the ionic liquid, the1H-NMR will contain comparatively fewer peaks, however the analysis is the same as the methyl hydrogen atoms of the EMIM cation are used for reference.

[0165] For quantification of other reaction products such as methanol, methyl formate and methyl propionate, the1H-NMR integrated area of methyl hydrogens (from each respective product) were similarly evaluated using the hydrogen atoms of the methyl group of the EMIM cation as a reference to obtain the yield relative to ionic liquid. P7243PC00

[0166] Example 1 - Experimental procedures for hydrogenation / dehydrogenation reactions

[0167] 1. 1 Generalized procedure for batch hydrogenation of CC at high pressure

[0168] A high-pressure reactor Teflon cup (max. volume 5 mL) was filled with 1 mL of the chosen ionic liquid and 0.02 mmol of the desired catalyst (here exemplified with Ru-2, 10 mg). Afterwards the reactor was purged three times with CO2, to remove all remnant air from the vessel, and pressurized with the desired amount of CO2, (e.g. 10 bars), followed by the addition of the desired amount of H2 (e.g. 20 bars), under stirring at 420 rpm. The reaction mixture was left running at the specified temperature and time. The reaction was stopped by releasing the remanent of pressure and the reaction mixture collected and analyzed by1H NMR using the ionic liquid as reference.

[0169] 1.2 Generalized procedure for batch hydrogenation of CO2 at high pressure with the addition of additives

[0170] The desired amount of additive (here exemplified with 90 mol% Et3N / l L (IL = ionic liquid), corresponding to 0.75 mL of Et3N) was added to the ionic liquid and catalyst mixture prior to purging with CO2. Aside from the additive addition, this methodology follows the same procedure as described above for batch hydrogenation without any additives present.

[0171] 1.3 Generalized procedure for hydrogenation of CO2 in continuous flow

[0172] In a 25 mL round bottom flask, 1 mL of the chosen ionic liquid and 0.02 mmol of the desired catalyst (here exemplified with Ru-2, 10 mg) were mixed at room temperature, under non-inert conditions in an open vial at a stirring of 420 rpm. Once a homogeneous solution was obtained and heated to the specified temperature, a mixture of CO2 and H2, the respective flows controlled by mass flow meters, were bubbled through the reaction mixture at different volume flow ratios ranging between 20 to 120 ml / min.1H NMR samples were taken during the selected reaction time to follow the conversion into formic acid.

[0173] The above-described procedure was also utilized and applies for imitated-air flow experiments and experiments that utilize low-concentration CO2 gas sources such as e.g., 500 ppm of CO2 in N2, or atmospheric air. P7243PC00

[0174] 7.4 Generalized procedure for batch dehydrogenation experiments of formic acid.

[0175] In a 50 mL two-neck flask, 1 mL of the chosen ionic liquid and 0.02 mmol of the desired catalyst (here exemplified with Ru-2, 10 mg) under stirring at 420 rpm at the set temperature (e.g. 80 °C, preferably above 45 °C). The flask was fitted with a condenser and a gentle flow of Ar was introduced to facilitate diffusion and outlet of any released gases (CO2 and H2). Once a homogeneous solution was obtained, 13.25 mmol (0.5 mL) of formic acid was added slowly to the reaction mixture. A vigorous gas formation was observed immediately. Samples were taken at different time points, e.g. after 30 min, to follow the dehydrogenation process until no formic acid could be identified by1H NMR (400 MHz, CD3CN) with a reaction limit of 3 hours. After the reaction time limit was reached (3h) the experiment was stopped, and the reaction mixture allowed to cool and collected for1H NMR analysis using the hydrogen signals of the methyl group of the EMIM cation as reference as described above.

[0176] 1.5 Generalized procedure for MeOH production

[0177] A high-pressure reactor Teflon cup (max volume 5 mL) was filled with 1 mL of the chosen ionic liquid and 0.02 mmol of the desired catalyst (here exemplified with Ru-2, 10 mg) and methyl formate (MF) (80-200 mol% MF / IL). Afterwards the reactor was purged gently three times with N2 to remove all air from the vessel, and loaded with the desired amount of H2 (e.g. 20 bars), under stirring at 420 rpm at 60 °C. The reaction mixture was subsequently left running at the specified temperature and time. After the reaction time was reached the experiment was stopped by releasing the remanent of pressure. The reaction mixture was collected and analysed by1H NMR using the ionic liquid as reference, giving a MeOH / IL yield of 33 % based on the hydrogen peak of the methyl group of methanol at 3.41 ppm (Reaction conditions 1mL EMIM-propionate, 20 bars H2, 0.02 mmol Ru-2, 200 mol% MF / IL, 420 rpm, 60 °C,18h).

[0178] 1.6 Generalized procedure for Methyl formate production

[0179] In a 100 mL round bottom flask, 10 mL of EMIM-propionate (59.7 mmol), 5 equivalents of formic acid (298 mmol, 15.10 mL) and 5 equivalents of MeOH (12.11 mL, 298.5 mmol) were stirred at 420 rpm under reflux (90-100 °C) for 18-20h. The system was connected to a cooling system (operation T < 6 °C) to avoid loss of solvent. Once the reaction was finished a1H-NMR sample was taken to quantify and verify methyl formate (MF) production and methyl propionate (MP) yielding a MF / IL yield of 68 % based on the peak at 3.75 ppm and a MP / IL yield of based on the peak at 3.66 ppm P7243PC00

[0180] (Reaction conditions 10 mL EMIM-propionate, 5 equivalents of FA and MeOH , 420 rpm, reflux 100 °C,18h).

[0181] 1.7 Generalized alternative procedure for batch hydrogenation of CO2 to methanol at high pressure

[0182] A high-pressure reactor Teflon cup (max. volume 5 mL) was filled with 1.5 g of the chosen ionic liquid, 0.05 mmol of the desired catalyst (here represented with commercial Ru-MACHO-BH CAS 1295649-41-0; Merck; 29 mg), and 0.1 mmol of the chosen additive (additives are the same as those represented by the data of Figs. 3- 11). Afterwards the reactor was purged three times with CO2, to remove all remnants air from the vessel, and pressurized with the desired amount of CO2, (e.g. 5 bars), followed by the addition of the desired amount of H2 (e.g. 30 bars), under stirring at 420 rpm. The reaction mixture was left running at 120-150 °C for 20-72h to achieve sufficient conversion. The reaction was stopped by releasing the remanent of pressure in a gas bag for GC analysis and the reaction mixture collected and analyzed by1H NMR using the ionic liquid as reference. Compared to procedure 1.1 , the lowered pressure of CO2 and increased pressure of H2 results in higher yield of methanol, which is advantageous because of a higher utilization degree of CO2.

[0183] Hydrogenation: a high-pressure reactor Teflon cup (max. volume 5 mL) was filled with 1 mL of the chosen ionic liquid and 0.05 mmol of the desired catalyst (here exemplified with Ru-2, 23.5 mg). Afterwards the reactor was purged three times with CO2, to remove all remnants air from the vessel, and pressurized with the desired amount of CO2, (e.g. 5 bars), followed by the addition of the desired amount of H2 (e.g. 15 bars), under stirring at 420 rpm. The reaction mixture was left running at 25-30 °C for a maximum of 24 hours. The reaction was stopped by releasing the remanent of pressure and the reaction mixture collected and analyzed by1H NMR using the ionic liquid as reference. Compared to procedure 1.1 , the lowered pressure of CO2 and increased pressure of H2 results in higher yield of formic acid, which is advantageous because of a higher utilization degree of CO2.

[0184] Dehydrogenation: after the hydrogenation step, the reaction mixture was heated to a temperature of 40-100 °C and maintained for a maximum of 24 hours under stirring at P7243PC00

[0185] 420 rpm leaving the autoclave open to release H2 and CO2. The reaction was stopped by cooling down at room temperature and the reaction mixture collected and analyzed by1H NMR using the ionic liquid as reference.

[0186] 1.9 Generalized alternative procedure for Methyl formate production using smaller amounts of FA and MeOH

[0187] In a 100 mL round bottom flask, 2 g of EM IM -form ate (12.8 mmol), 0.6 equivalents of formic acid (7.68 mmol, 0.29 mL) and 1.2 equivalents of MeOH (15.3 mmol, 0.62 mL) were stirred at 420 rpm under reflux (80 °C) for 20h. The system was cooled with ice to avoid loss of solvent. Once the reaction was finished a 1 H-NMR sample was taken to quantify and verify methyl formate (MF) production (yield of 16 % based on FA). The yield may be increased to 20% by increasing the reflux time to 72h. optionally, a small amount (50 pL) cone. H2SO4 may also be added to the reaction mixture to facilitate an increase in yield.

[0188] (Reaction conditions 2 g EMIM-propionate, 0.5 equivalents of FA, and 3 equivalents of MeOH, 420 rpm, reflux 80 °C, 20h). Compared to 1.6, the substoichiometric amount of formic acid to ionic liquid resembles a situation where formic acid is generated arise from catalytic CO2 hydrogenation.

[0189] Results

[0190] Exemplary Figs. 1 and 2 illustrate the different CO2 hydrogenation yields obtained following the procedure outlined in Example 1.1 by investigation various combinations of specific catalyst and ionic liquid combination. In particular, the combination Ru- 2 / EMIM-propionate provides a superior yield which could not have been predicted and significantly improves on already established state-of-the art Ru-1 / EMIM-acetate known from Piccirilli et al (2023). The results obtained at 30 °C are summarized in Table 1 here below, but the superiority of Ru-2 / EMIM-propionate is also evident at higher temperatures such as 50 °C.

[0191] Table 1 - Hydrogenation results (mol% (FA / IL yield)) obtained from variation of ionic liquid and catalyst. Reaction conditions: 10:20 bar (CO2:H2, totalling 30 bars), 1 ml of IL, 420 rpm, 6h / 18h with 0.02 mmol catalyst at 30 °C. P7243PC00

[0192] The effect of various additives on the formic acid (FA) yield as obtained by hydrogentation of CO2 in the presence of an ionic liquid and a suitable Ru-based catalyst is investigated following the generalized procedure outlined in Example 1.2 and illustrated in Figs. 3 to 11.

[0193] Fig. 3 illustrates the effect of adding a base to the reaction mixture in an amount corresponding to 90 mol% base / IL wherein the reaction media comprises the Ru- 2 / EMIM-acetate pair. It is noteworthy that base additives generally increase formic acid yields substantially, with the exception of very apolar bases such as trioctylamine. In particular dipropylamine and triethylamine more than triple the FA yield from 34 mol% (no base additive) to 108 mol% and 111 mol% respectively which could not have been predicted beforehand (Reaction conditions: 10:20 bar (CO2:H2), 1 ml of EMIM-OAc, 90 mol% base / IL, 420 rpm, 18h with 0.02 mmol Ru-2 at 30 °C).

[0194] Fig. 4 illustrates the effect of adding an acid to the reaction mixture in an amount corresponding to 30 mol% acid / IL wherein the reaction media comprises the Ru- 2 / EMIM-propionate pair. Even more noteworthy is that the formic acid yield seems not to be exclusively favoured by base additives, but also by Bronsted acid additives such as in particular phosphoric acid (H3PO4) and propionic acid which consistently increase the yield approximately 5-fold and 3.5-fold, respectively. Neutral additives such as water and methanol also increase the formic acid yield, albeit to a lesser extent.

[0195] Figs. 5A-5B illustrates the formic acid yield by CO2 hydrogenation using triethylamine as an additive and screening the amount of additive included in the reaction mixture. Specifically, Fig. 5A evaluates IL = EMIM-formate and finds that in general, triethylamine has a positive effect on the formic acid yield with 50 mol% being the optimum. Fig. 5B evaluates IL = EM IM -acetate and finds that at relative low concentrations (33-80 mol%) the effect is negligible whereas at 200 mol% or above, the effect on FA yield becomes negative. However, at 90 mol% and 125 mol%, the Ru- P7243PC00

[0196] 2 / EMIM-acetate / EtsN mixture presents an optimum experiencing a drastic positive increase in FA / IL yield, especially at 30 °C increase from 34 mol% FA / IL in the neat case, and up to 110 mol% FA / IL and 102 mol% FA / IL. Fig. 6 evaluates formic acid yield by CO2 hydrogenation using triethylamine as an additive under the same reaction conditions as presented for Fig. 5A-5B (except IL = EMIM-propionate and temp = 30 °C) and generally finds FA yields to be higher for this ionic liquid than for the formate and acetate counterparts. 80 mol% Et3N represents the optimum amount of this base additive to achieve the highest mol% FA / IL yield In the Ru-2 / EMIM-propionate / Et3N mixture.

[0197] Fig. 7 evaluates the effect of methanol as an additive for CO2 hydrogenation.

[0198] Fig. 8 evaluates the effect of water as an additive for CO2 hydrogenation in both EMIM- acetate (Fig. 8A) and EMIM-propionate (Fig. 8B). Furthermore, the fact that water can be included as an additive also highlights an important feature of the described methodology, namely that it does not require strictly anhydrous conditions, and in fact under certain conditions can benefit from the inclusion of water into the reaction mixture.

[0199] Interestingly, Figs. 9 to 11 shed light on the kinetics of CO2 hydrogenation in the presence of triethylamine (i.e. as additive), and demonstrates (see Fig. 9) that although the Ru-2 / EMIM-propionate system achieves the highest overall FA yield, the Ru- 2 / EMIM-OAc system achieves a very high yield of 111 mol% FA / IL already after 6 hours, whereas the Ru2-EMIM-propionate requires 18 hours for the same conversion.

[0200] For Bronsted acid additives, formic acid itself may also function as an accelerator for hydrogenation, as evidenced in Fig. 10. Here, 30 mol% FA is added directly to the reaction media comprising Ru-2 / EMIM-propionate before any CO2 is introduced. As a consequence, the FA yield shoots up after only three hours of conversion reaching 50 mol% FA / IL at 3 hours and 68 mol% FA / IL at 6 hours, which is striking when compared to the identical non-additive reaction yielding only 6 mol% and 10 mol% FA / IL at 3 and 6 hours of hydrogenation, respectively.

[0201] Combining the teachings obtained from Fig. 9 and Fig 10, CO2 hydrogenation under batch conditions (still as outlined under generalized procedure 1.2) was performed P7243PC00 using a mixture of both Bronsted acid and base additives. To that end, a CO2 hydrogenation experiment was conducted utilizing both 90 mol% triethylamine and 30 mol% formic acid as additives ahead of starting hydrogenation (Ru-2 / EMIM-acetate pair). For completeness, the comparative single-additive experiments were also performed and included in Fig. 11.

[0202] Surprisingly, the multi-additive experiment demonstrated a synergistic effect between using a base and a Bronsted acid additive, reaching a staggering 30 mol% FA / IL yield after only 2 hours of operation. By contrast, each of the single-additive experiments (30 mol% FA or 90 mol% EtsN) achieved less than 10 mol% FA / IL (7 mol% and 2 mol% FA / IL, respectively).

[0203] To examine hydrogenation under continuous flow conditions, the generalized procedure outlined in 1.3 was implemented in a series of experiments and results obtained from these experiments using various volume-flow conditions and Ru-2 catalyst loadings can be found in Figs. 12A-12C. Together, these data clearly demonstrate the broad applicability of the described system, specifically the mixture of EMIM-propionate and Ru-2 catalyst for hydrogenation of CO2 into formic acid, achieving yields up to 67 mol% FA / IL in less than 3 hours of continuous operation depending on the amount of catalyst used and concentration of CO2 in the feed gas.

[0204] Turning to the reverse reaction, namely dehydrogenation of formic acid as outlined in generalized procedure 1.4, the results obtained from formic acid dehydrogenation batch experiments using various temperatures and Ru-2 catalyst loadings can be found in Figs 13A-13B. Together, these data clearly demonstrate that formic acid can be efficiently (up to 100%) dehydrogenated in a mixture of EMIM-propionate and Ru-2, and rapidly so, when the temperature is at least 50 °C. With higher loadings of catalyst, the temperature may be lowered even further to 40 °C to reduce energy requirements while still favouring dehydrogenation.

[0205] Example 2 - using EMIM-propionate for direct capture of CO2 from ambient air

[0206] 2. 1 Removal of CC from imitated air in low concentrations.

[0207] In this experiment, a gas feed initially containing 500 ppm CO2 in N2 was exposed to EMIM-propionate for 1 hour at 30 °C. GC-TCD analysis of the gaseous parts were P7243PC00 done both before and after contact. In the ‘after contact’ sample, the intensity of the GC-TCD peak corresponding to carbon dioxide had decreased from 3217.9 to only 55.6, indicating that >98% of CO2 has been removed from the gas phase of the mixture (see Fig. 14).

[0208] No catalyst was added to the mixture in this experiment and consequently, the data credibly demonstrates that the ionic liquid EMIM-propionate alone may function as a very efficient CO2 scavenger even in low-concentration atmospheres such as ambient air.

[0209] 2.2 One-pot sequential capture and hydrogenation of CO2 into formic acid.

[0210] In these experiments, the entire process was carried out inside a single reactor. CO2(1 bar) was flowed over the surface of EMIM-propionate for 5, 15, and 30 minutes or bubbled through the IL, which was in either case pre-mixed with 0.02 mmol Ru-2 and kept at 30 °C. After each specified reaction time, the CO2gas source was switched off, and no CO2was left inside the reactor. Then, 20 bars of H2were added, and the reaction was stirred for 18 h at 30 °C.

[0211] Fig. 15 further shows that the hydrogenation of CO2 to formic acid can be done sequentially in a two-step manner if desired, such as to initially capture CO2 from the atmosphere or other source, and subsequently hydrogenate the captured CO2.

[0212] 2.3 CO2 capture in ionic liquids evidenced with isotopically enriched CO2.

[0213] The hydrogenation experiments were conducted using 0.02 mmol of Ru-2 catalyst under varying pressure conditions, utilizing either 10 bars or 1 bar of CO2 in N2 (provided as 500 ppm13CC>2 in N2) in combination with 20 bars of H2 as the hydrogenation feed stream, each time in conjunction with 1 ml of EMIM-propionate. Prior to initiating the reaction, the system was purged with N2. The reactions were maintained at a constant temperature of 30 °C for 18 h. Conversion rates were quantified via1H and13C NMR spectroscopy as previously described.

[0214] The MS analysis conducted on the reaction mixture (here exemplified from a reaction employing 1 bar of CO2 in N2 (provided as 500 ppm13CC>2 in N2) in combination with 20 bars of H2) revealed a spectra exhibiting distinct peaks at m / z 44.998 and 45.993, which were identified as12C-formate (H12COO‘) and13C-formate (H13COO‘) P7243PC00 respectively. The precise alignment of these measurements with the calibrated mass accuracy of the spectrometric equipment confirms the conversion of13CC>2 into formate at a concentration even as low as 500 ppm, supporting the functionality of the EMIM- propionate in facilitating this transformation.

[0215] The MS data was acquired and analysed on an Orbitrap Exploris 120 from Thermo Fisher Scientific equipped with a heated electrospray ionization (HESI) probe. This instrument operated at a full width at half maximum (FWHM) resolution of 30,000 at m / z 200, with a scan rate of 12 Hz..

[0216] The presence of formate peaks corresponding to both12CO2and13CO2can be attributed to the IL capturing CO2from the air, indicating that the formic acid produced originated from both ambient CO2and, the 1 bar input of13CO2at 500 ppm. This dual source of CO2highlights the IL's ability to capture and convert CO2from different environments, thereby supporting the overall efficiency of the reaction.

[0217] 2.4 Cyclic CO2 capture from imitated air in low concentrations and release at higher concentrations.

[0218] Absorption: a gas feed imitating air containing 500 ppm CO2in N2 was exposed to 1 mL of EMIM-propionate for the desired time (2-18 h) at 30 °C. MicroGC analysis of the gaseous parts were done after contact at a rate of one measurement every 6 minutes. In the ‘after contact’ measurements, MicroGC indicated that CO2 has been removed from the gas phase of the mixture and accumulated in the IL (Figure 17).

[0219] Desorption: the IL mixture containing absorbed CO2 was heated at the desired temperature (40-100 °C) and flushed with the desired flow of nitrogen (here exemplified with a modest flow of 2 mL / min) to facilitate the release of CO2. The desorbed CO2 was measured by MicroGC (Figure 18). Once the CO2 was fully removed, the system was cooled at room temperature for a new absorption cycle.

[0220] Example 3 - SILP (supported ionic liquid phase) materials

[0221] 3. 1 General procedure for Ru-SILP preparation.

[0222] All manipulations are performed under Schlenk conditions or inside a glovebox. For this example, the solid porous material was for illustrative purposes selected as a silica P7243PC00

[0223] (pore volume of 0.55 cm3 / g; surface area of 161 m2 / g) but it will be readily apparent to the skilled person that other porous materials could be used as alternatives. Brunauer- Emmett-Teller (BET) surface area and porosity analysis were conducted by nitrogen physisorption performed at -196 °C by a Micromeritics ASAP 2020 instrument.

[0224] The amount of IL for the SILP preparation is calculated using the generalized formula here below:

[0225] (0 * msi02* pvsi02* pIL)

[0226] 100 “m,L

[0227] 0 = desired pore filling expressed in %, e.g., 20 msiO2= mass of silica in g pv so2= pore volume of the silica in cm3 / g p = density of the IL in g / cm3mu. = mass of the IL in g

[0228] The SILP catalysts were prepared by the impregnation method. The desired amount of IL (based on the selected pore filling, 0) was firstly dissolved in dry DCM with the desired amount of Ru catalyst, (calculated as Ru / SiC>2wt%) under inert conditions. Once a homogenous solution is obtained, the required amount of silica is combined to the DCM mixture, and the solution is stirred extremely slowly for no more than 20 min to avoid mechanical stress on the support material. Finally, the solvent is evaporated under vacuum, and the Ru-SILP material is stored in a glovebox until use. Prior to initiating the SILP synthesis, the silica support was calcined at 500 °C overnight with the intention of removing water and any impurities from the material and stored in a glovebox before use.

[0229] SILP catalysts were produced following the above generalized procedure for IL = EMIM-propionate, EMIM-acetate, EMIM-formate; and for Ru / SiC>2 wt% loadings from 1.0 to 2.5 wt%. with pore fillings from 20 % to 50%. The ionic liquid density was set at 1.1 g / cm3. P7243PC00

[0230] 3.2 Hydrogenation of CO2 into formic acid using SILP materials.

[0231] The experimental procedure consisted of placing the SILP catalyst (EMIM-propionate, Ru / SiC>2 1wt%) into a continuous-flow reactor and exposing it to a gas flow mixture of 2000 ppm CO2 in H2 at a flow rate of 6 L / h, with temperature ramps of 10 °C / h starting from 80 °C to 140 °C. The total duration was approximately 8 h including reactor cool down. The exhaust from the gas flow mixture was analysed every 5 seconds using IR- FID throughout the entire experimental process. This temperature range was chosen to evaluate the performance of the SILPs with the aim of combining CO2 capture with simultaneous hydrogenation to FA and its subsequent release from the SILP catalyst.

[0232] Five further hydrogenation cycles were tested.

[0233] The first two hydrogenation cycles followed a similar procedure as had previously been tested for EMIM-acetate, where the sample was submitted to a gas mixture of 2,000 ppm of CO2 in H2 at 6L / h with 10 °C / h temperature ramps starting from 40 °C to 80 °C.

[0234] The third hydrogenation cycles followed the same experimental protocol as described immediately above (gas mixture of 2,000 ppm of CO2 in H2 at 6L / h with 10 °C / h temperature ramps starting from 40 °C to 80 °C), but extending the duration at 80 °C for 4 h while maintaining the CO2 / H2 gas mixture flow through the SILP.

[0235] The fourth hydrogenation cycle was conducted with modified temperature conditions, starting from 30 °C to 140 °C, with 10 °C / h ramps and a gas flow mixture of 2,000 ppm CO2 in H2 at 6L / h.

[0236] The fifth hydrogenation cycle was conducted first by heating the sample at 140 °C under N2 flow for cleaning until no FA was observed. Then, the gas flow was switched back to the 2,000 ppm CO2 in H2 mixture (6L / h) while maintaining the temperature at 140 °C.

[0237] In all of the above hydrogenation experiments, FA was observed as produced and released from the SILP material. It is noted in this regard that the present experiments were conducted at ambient pressure and low CO2 concentration which does not favour very high yields, but nevertheless illustrates that the EMIM-propionate SILP material can hydrogenate CO2 into formic acid. P7243PC00

[0238] To further test the SILP system, the CO2 concentration of the feed stream was elevated from 2,000 ppm to 20% (200,000 ppm). Simultaneously, the Ru / SiC>2 weight percentage was increased from 1% to 2.5%.

[0239] Experiments were conducted at temperatures exceeding 80 °C to assess both FA production and its subsequent release. These investigations were designed to validate the temperature threshold required for FA release without competing with the dehydrogenation process and, to ascertain the SILPs' capability to absorb CO2 at temperatures surpassing 30 °C.

[0240] Three hydrogenation cycles were performed. The initial two hydrogenation cycles involved a temperature decrease from 110 °C to 80 °C, while the third cycle entailed an increase in the temperature range from 110 °C to 150 °C. In between of every cycle a pre-cleaning procedure under N2 flow at 110 °C was performed until no FA was detected from previous hydrogenation cycles before switching back the 20% CO2 / H2 gas flow mixture.

[0241] The results revealed a notable CO 2 uptake during the first two hydrogenation cycles, accompanied by the detection of FA. For both the EMIM-propionate- and EMIM- acetate-SILP, FA desorption followed the temperature fluctuations, decreasing concurrently with each temperature reduction.

[0242] For the third hydrogenation cycle, CO2 uptake is observed and FA detected in the product. As expected, FA concentration increase with every temperature ramp.

[0243] Interestingly, the observed FA concentration achieved using the EMIM-propionate SILP was 533% higher as what was achieved with the analogous EMIM-acetate-SILP.

[0244] This indication points out that propionate is a better anion for CO2 hydrogenation. In addition, no modification in the CO2 concentration was observed indicating that dehydrogenation does not take place to any measurable extent. P7243PC00

[0245] References

[0246] Piccirilli et al (2023) - Versatile CO2 hydrogenation-dehydrogenation catalysis with Ru- PNP / ionic liquid system; J. Am. Chem. Soc, 2023, Vol 145, 10, 5655-5663 https: / / d0i.0rg / l 0.1021 / jacs.2c10399

[0247] Items

[0248] 1. A method for the catalytic hydrogenation of carbon dioxide (CO2) into a value- added product selected from formic acid, methyl formate, methyl propionate and methanol, the method comprising a step of contacting a feed stream comprising CO2 and H2 with a reaction media, wherein the reaction media comprises an ionic liquid (IL) and a ruthenium (Ru)-based pincer complex, further wherein the H2 / CO2 volume ratio in the feed stream is from 50:1 to 1:1000.

[0249] 2. The method according to any one of the preceding items, wherein the feed stream is gaseous or liquid.

[0250] 3. The method according to any one of the preceding items, wherein feed stream comprises contaminant gasses or impure gasses, such as wherein the feed stream is ambient air.

[0251] 4. The method according to any one of the preceding items, wherein the value added product is formic acid.

[0252] 5. The method according to any one of the preceding items, wherein the value added product is methyl formate.

[0253] 6. The method according to any one of the preceding items, wherein the ionic liquid comprises an imidazolium-based cation and an anion which is a Ci-Ce carboxylate, Cl , Br, I, hexafluorophosphate, tetrafluoroborate, trifluoromethanesulfonate, bis(trifluoromethanesulfonimide) or hydrogen sulphate. P7243PC00

[0254] 7. The method according to any one of the preceding items, wherein the ionic liquid anion is formate, acetate (OAc), propionate or butanoate .

[0255] 8. The method according to any one of the preceding items, wherein the ionic liquid is 1-ethyl-3-methylimidazolium formate (EMIM-formate), 1-ethyl-3- methylimidazolium acetate (EM IM -acetate), 1-ethyl-3-methylimidazolium propionate (EMIM-propionate), 1-propyl-3-methylimidazolium formate (PMIM- formate), 1-propyl-3-methylimidazolium acetate (PMIM-acetate), 1-propyl-3- methylimidazolium propionate (PMIM-propionate), 1-butyl-3-methylimidazolium formate (BMIM-formate), 1-butyl-3-methylimidazolium acetate (BM IM -acetate) or 1-butyl-3-methylimidazolium propionate (BMIM-propionate).

[0256] 9. The method according to any one of the preceding items, wherein the ionic liquid is EMIM-propionate, EMIM-acetate or EMIM-formate, preferably EMIM- propionate.

[0257] 10. The method according to any one of the preceding items, wherein the pincer complex is of formula (I) wherein,

[0258] M is ruthenium;

[0259] W is an atom selected from the group consisting of P, C, O, and N;

[0260] R1a, R1a’, R1band R1b’ are each independently selected from the group consisting of Ci-Ce alkyl, isopropyl, tert-butyl, a C3-C7 cycloalkyl, a C3-C7 heterocycloalkyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl;

[0261] Z is selected from CO, P(RIH)3, As(RIH)3, NO and N2; and P7243PC00

[0262] X is selected from the group consisting of a hydridoborate, such as tetrahydridoborate (BH4'), a halide, such as F, Cl, Br, or I, a carboxylate, such as formate, acetate or propionate, and H, wherein R111is each individually selected from Ci-Ce alkyl, isopropyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl.

[0263] 11 . The method according to any one of the preceding items, wherein the pincer complex is of formula (II) wherein,

[0264] M is ruthenium;

[0265] R1a, R1a’, R1band R1b’ are each independently selected from the group consisting of Ci-Ce alkyl, isopropyl, tert-butyl, a C3-C7 cycloalkyl, a C3-C7 heterocycloalkyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl;

[0266] Z is selected from CO and NO; and

[0267] X is selected from H and Cl.

[0268] 12. The method according to any one of the preceding items, wherein R1a, R1a’, R1band R1b’ are each independently selected as phenyl or isopropyl, each of which may optionally be substituted by one or more selected from halogen, cyano, amino, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl. P7243PC00

[0269] 13. The method according to any one of the preceding items, wherein R1a, R1a’, R1band R1b’ are each independently selected as phenyl or isopropyl.

[0270] 14. The method according to any one of the preceding items, wherein R1a, R1a’, R1band R1b’ are all selected as either phenyl or isopropyl.

[0271] 15. The method according to any one of the preceding items, wherein the pincer complex is of formula (III) wherein X is Cl or H.

[0272] 16. The method according to any one of the preceding items, wherein Z is CO and X is H.

[0273] 17. The method according to any one of the preceding items, wherein the pincer complex is Ru(H)2(CO)(iPrPNP) (iPrPNP: bis(2- (diisopropylphosphaneyl)ethyl)amine).

[0274] 18. The method according to any one of the preceding items, wherein the pincer complex is of formula (IV) P7243PC00

[0275] 19. The method according to any one of items 10 to 14, wherein Z is CO and X is Cl.

[0276] 20. The method according to any one of items 10 to 14, wherein the pincer complex is Ru(H)(CO)(CI)(iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

[0277] 21. The method according to any one of items 10 to 14, wherein the pincer complex is of formula (V) formula (V)

[0278] 22. The method according to any one of the preceding items, wherein the pincer complex has the function of a catalyst, such as a homogeneous catalyst.

[0279] 23. The method according to any one of the preceding items, wherein the catalyst is present in an amount between 0.01% and 5% (w / w) based on weight of the ionic liquid.

[0280] 24. The method according to any one of the preceding items, wherein the catalyst is present in an amount between 0.01% and 5% (mol%) based on the amount of the ionic liquid.

[0281] 25. The method according to any one of the preceding items, wherein the ionic liquid is EMIM-propionate and the catalyst is present in an amount between 0.01% and 5% (mol%) based on the amount of the EMIM-propionate, such as between 0.1% and 1% (mol%) based on the amount of the EMIM-propionate.

[0282] 26. The method according to any one of the preceding items, wherein the ionic liquid is EMIM-acetate and the catalyst is present in an amount between 0.01% and 5% (mol%) based on the amount of the EMIM-acetate, such as between 0.1% and 1% (mol%) based on the amount of the EMIM-acetate . P7243PC00

[0283] 27. The method according to any one of the preceding items, wherein the feed stream comprises essentially of CO2 and H2.

[0284] 28. The method according to any one of the preceding items, wherein the feed stream comprises CO2 in a concentration from 1000 ppm to 500.000 ppm, such as from 10.000 ppm to 200.000 ppm.

[0285] 29. The method according to any one of the preceding items, wherein the feed stream comprises CO2 in a concentration of less than 50000 ppm.

[0286] 30. The method according to any one of the preceding items, wherein the feed stream comprises CO2 in a concentration of less than 5000 ppm.

[0287] 31 . The method according to any one of the preceding items, wherein the feed stream comprises CO2 in a concentration from 200 to 1000 ppm.

[0288] 32. The method according to any one of the preceding items, wherein the CO2 is provided at a pressure between 1 and 40 bar, such as between 1 and 15 bar.

[0289] 33. The method according to any one of the preceding items, wherein the hydrogen is provided at a pressure between 1 and 40 bar, such as between 1 and 20 bar.

[0290] 34. The method according to any one of the preceding items, wherein the H2 / CO2 ratio is from 50:1 to 1 :2

[0291] 35. The method according to any one of the preceding items, wherein the H2 / CO2 ratio is 20:1.

[0292] 36. The method according to any one of the preceding items, wherein the H2 / CO2 ratio is 5:1.

[0293] 37. The method according to any one of the preceding items, wherein the H2 / CO2 ratio is 1 :1. P7243PC00

[0294] 38. The method according to any one of the preceding items being performed under ambient pressure and / or temperature.

[0295] 39. The method according to any one of the preceding items wherein the feed is ambient air.

[0296] 40. The method according to any one of the preceding items, wherein the feed stream is provided at a total pressure between 1 and 200 bar, such as between 1 and 40 bar, such as between 1 and 20 bar.

[0297] 41. The method according to any one of the preceding items, wherein the hydrogenation is carried out at temperature between 25 °C and 200 °C.

[0298] 42. The method according to any one of the preceding items, wherein the hydrogenation is carried out at 30(±5) °C, such as 30 °C.

[0299] 43. The method according to any one of the preceding items, wherein the hydrogenation is carried out at temperature between 50(±5) °C, such as 50 °C.

[0300] 44. The method according to any one of the preceding items, further comprising the addition of at least one additive in an amount which increases at least one of: i) formic acid yield; and / or ii) formic acid production rate, as compared to without addition of said additive under the same reaction conditions.

[0301] 45. The method according to any one of the preceding items, wherein the reaction conditions are at least 10:20 bar (CO2:H2), 1 ml of IL, 420 rpm, 18h with 0.02 mmol catalyst at 30 °C.

[0302] 46. The method according to any one of the preceding items, wherein the at least one additive is a Bronsted acid.

[0303] 47. The method according to any one of the preceding items, wherein the at least one additive is a base, with the proviso that the base is not trioctylamine. P7243PC00

[0304] 48. The method according to any one of the preceding items, wherein the at least one additive is a C3-15 alkylamine, preferably a secondary or tertiary C3-15 alkylamine.

[0305] 49. The method according to any one of the preceding items, wherein the at least one additive is selected from H3PO4, formic acid, ethanoic acid, propionic acid, dibutylamine, diethylamine, dipropylamine, tributylamine, triethylamine, propylamine, tripropylamine, N,N-diethylethylenediamine, water, methanol, and ethanol.

[0306] 50. The method according to any one of the preceding items, wherein the at least one additive is selected from H3PO4, formic acid, propionic acid, dipropylamine, and triethylamine.

[0307] 51 . The method according to any one of the preceding items wherein the at least one additive is a mixture of a Bronsted acid and a base, such as a mixture of formic acid and triethylamine.

[0308] 52. The method according to any one of the preceding items, wherein the additive is added in an amount ranging from 1 mol% to 300 mol% based on the amount of ionic liquid.

[0309] 53. The method according to any one of the preceding items, wherein the additive is triethylamine and is added in an amount ranging from 80 mol% to 90 mol% based on the amount of ionic liquid.

[0310] 54. The method according to any one of the preceding items, wherein the ionic liquid is EM IM -acetate and the additive is triethylamine, preferably in an amount corresponding to 33 mol% to 125 mol%, more preferably 90 mol% triethylamine based on the amount of EMIM-acetate.

[0311] 55. The method according to any one of the preceding items, wherein the ionic liquid is EMIM-propionate and the additive is triethylamine, preferably 3 mol% to P7243PC00

[0312] 80 mol%, more preferably 50 mol% triethylamine based on the amount of EMIM-propionate.

[0313] 56. The method according to any one of the preceding items, wherein the ionic liquid is EMIM-propionate and the additive is methanol, preferably 10 mol% to 50 mol% methanol based on the amount of EMIM-propionate.

[0314] 57. The method according to any one of the preceding items, wherein the at least one additive is not water.

[0315] 58. A catalytic system for reversible hydrogenation and dehydrogenation of a liquid organic hydrogen carrier (LOHC) pair, the system the ionic liquid EMIM- propionate and the transition metal pincer complex Ru(H)(CO)(CI)(iPrPNP) (iprPNp:bis(2-(diisopropylphosphaneyl)ethyl)amine).

[0316] 59. The system according to item 58, wherein the LOHC pair is FA / CO2.

[0317] 60. An apparatus for producing electricity comprising a fuel cell and a catalytic system according to any one of items 58 to 59.

[0318] 61 . Use of the catalytic system according to any one of items 58 to 59 for providing hydrogen to a fuel cell for producing electricity.

[0319] 62. Use of a reaction media comprising 1-ethyl-3-methylimidazolium propionate (EMIM-propionate) and homogeneous catalyst Ru(H)(CO)(CI)(iPrPNP) for hydrogenation of CO2 into formic acid (FA).

[0320] 63. The use according to item 62 wherein the reaction media does not comprise water.

[0321] 64. The use of any one of items 62 to 63 wherein the reaction media further comprises a Bronsted acid and / or Bronsted base.

[0322] 65. Use of EMIM-propionate as a media for capture of CO2. P7243PC00

[0323] 66. The use according to item 65 wherein the CO2 is captured directly from an atmospheric source.

[0324] 67. The use according to any one of items 65 to 66, wherein the CO2 is captured under ambient conditions, such as under ambient pressure and / or temperature.

[0325] 68. The use according to any one of items 65 to 67, wherein the atmospheric source comprises CO2 in a concentration of less than 5000 ppm.

[0326] 69. The use according to any one of items 65 to 68, wherein the atmospheric source comprises CO2 in a concentration of 200 ppm to 1000 ppm.

[0327] 70. The method according to any one of items 1 to 57, wherein the reaction media further comprises a porous solid material, such as wherein the reaction media is a SILP (supported ionic liquid phase), optionally wherein the porous solid material is alumina, titania, silica, carbon, MgO, ceria, zirconia, or mixed oxides, such as MgAI spinel and ZrCe oxides, preferably silica.

[0328] 71 . The method according to item 70, wherein the pincer complex catalyst may be provided in an amount corresponding to from 0.1 wt% to 10 wt% of the porous solid material, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 .0 wt%, 2.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10 wt% or any 0.1 wt% incremental value therein between.

[0329] 72. The method according to any one of items 70 to 71 , wherein the pincer complex catalyst may be provided in an amount corresponding to from 1.0 wt% to 5 wt%.

[0330] 73. The method according to any one of items 70 to 72, wherein the porous solid material is characterized by a pore volume from 0.20 cm3 / g to 1.00 cm3 / g, preferably from 0.40 cm3 / g to 0.80 cm3 / g, more preferably from 0.50 cm3 / g to 0.60 cm3 / g. P7243PC00

[0331] 74. The method according to any one of items 70 to 73, wherein the porous solid material is characterized by a surface area from 70 m2 / g to 300 m2 / g, preferably from 120 m2 / g to 200 m2 / g, more preferably from 140 m2 / g to 180 m2 / g. 75. The method according to any one of items 70 to 74, wherein the SILP comprises EMIM-propionate, Ru-2 and silica, wherein the silica has a pore volume of 0.55(5) cm3 / g and a surface area of 160(5) m2 / g.

[0332] P7243PC00

[0333] Items 2

[0334] 1. A method for catalytic hydrogenation of carbon dioxide (CO2) into formic acid, the method comprising a step of contacting a feed stream comprising CO2 and H2, together or separately, with a reaction media, wherein the reaction media comprises an ionic liquid (IL) 1-ethyl-3-methyl-imidazolium propionate (EMIM- propionate) and a ruthenium (Ru)-based homogeneous catalyst, further wherein the H2 / CO2 volume ratio in the feed stream is from 50:1 to 1 :1000.

[0335] 2. The method according to item 1 , wherein the catalyst is of formula (II) wherein,

[0336] M is ruthenium;

[0337] R1a, R1a’, R1band R1b’ are each independently selected from the group consisting of Ci-Ce alkyl, isopropyl, tert-butyl, a C3-C7 cycloalkyl, a C3-C7 heterocycloalkyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl;

[0338] Z is selected from CO and NO; and

[0339] X is selected from H and Cl.

[0340] 3. The method according to any one of the preceding items, wherein the catalyst is of formula (III) P7243PC00

[0341] (HI) wherein X is Cl or H.

[0342] 4. The method according to any one of the preceding items, wherein the catalyst is of formula (V) formula (V)

[0343] 5. The method according to any one of the preceding items, wherein the catalyst is present in an amount between 0.01 and 5% (mol%) based on the amount of the EMIM-propionate.

[0344] 6. The method according to any one of the preceding items, wherein the feed stream comprises CO2 in a concentration from 10 ppm to 50.000 ppm, wherein the H2 / CO2 ratio is between 5:1 and 1 :2 and wherein the hydrogenation is carried out at temperature between 25 °C and 55 °C.

[0345] 7. The method according to any one of the preceding items, further comprising addition of at least one additive in an amount ranging from 3 mol% to 300 mol% based on the amount of the ionic liquid which increases at least one of: i) formic acid yield; and / or ii) formic acid production rate, as compared to the same reaction without the addition of said additive, performed under the conditions 10:20 bar (CO2:H2), 1 ml of the ionic liquid, 420 rpm, 18 hours reaction time with 0.02 mmol catalyst at 30 °C.

[0346] 8. The method according to any one of the preceding items, wherein the at least one additive is one or more of formic acid, H3PO4, propionic acid, triethylamine or dipropylamine. P7243PC00

[0347] 9. The method according to any one of the preceding items, wherein the at least one additive is a mixture of triethylamine and formic acid.

[0348] 10. The method according to any one of the preceding items, wherein the ionic liquid is EMIM-propionate and the additive is triethylamine, preferably 3 mol% to 80 mol%, more preferably 50 mol% triethylamine; or wherein the ionic liquid is EMIM-propionate and the additive is methanol, preferably 10 mol% to 50 mol% methanol.

[0349] 11 . A catalytic system for reversible hydrogenation and dehydrogenation of a liquid organic hydrogen carrier (LOHC) pair, the system comprising the ionic liquid EMIM-propionate and the transition metal pincer complex Ru(H)(CO)(CI)( iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine), wherein the LOHC pair is formic acid / CO2.

[0350] 12. Apparatus for producing electricity comprising a fuel cell and the catalytic system according to item 11 .

[0351] 13. Use of the catalytic system of item 11 for providing hydrogen to a fuel cell for producing electricity.

[0352] 14. Use of a reaction media comprising 1-ethyl-3-methylimidazolium propionate (EMIM-propionate) and homogeneous catalyst Ru(H)(CO)(CI)(iPrPNP) in hydrogenation of CO2 into formic acid (FA).

[0353] 15. Use of EMIM-propionate as a media for capture of CO2 from a gaseous source, such as an atmospheric source.

Claims

1. P7243PC00Claims1 . A method for catalytic hydrogenation of carbon dioxide (CO2) into formic acid, the method comprising a step of contacting a feed stream comprising CO2 and H2, together or separately, with a reaction media, wherein the reaction media comprises an ionic liquid (IL) 1-ethyl-3-methyl-imidazolium propionate (EMIM- propionate) and a ruthenium (Ru)-based homogeneous catalyst, further wherein the H2 / CO2 volume ratio in the feed stream is from 50:1 to 1 :1000.

2. The method according to the preceding claim, wherein the feed stream is gaseous or liquid.

3. The method according to any one of the preceding claims, wherein feed stream comprises contaminant gasses or impure gasses, such as wherein the feed stream is ambient air.

4. The method according to any one of the preceding claims, wherein the catalyst is of formula (II)wherein,M is ruthenium;R1a, R1a’, R1band R1b’ are each independently selected from the group consisting of Ci-Ce alkyl, isopropyl, tert-butyl, a C3-C7 cycloalkyl, a C3-C7 heterocycloalkyl, phenyl, and C5-C10 aryl, each of which may optionally be substituted by one or more selected from halogen, CN, NH2, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl;Z is selected from CO and NO; andX is selected from H, BH4, and Cl.P7243PC005. The method according to claim 4, wherein R1a, R1a’, R1band R1b’ are each independently selected as phenyl or isopropyl, each of which may optionally be substituted by one or more selected from halogen, cyano, amino, Ci-Ce alkyl, Ci-Ce alkoxy, phenyl, and C5-C10 aryl.

6. The method according to any one of claims 4 to 5, wherein R1a, R1a’, R1band R1b’ are each independently selected as phenyl or isopropyl.

7. The method according to any one of claims 4 to 6, wherein R1a, R1a’, R1band R1b’ are all selected as either phenyl or isopropyl.

8. The method according to any one of the preceding claims, wherein the catalyst is of formula (III)wherein X is Cl or H.

9. The method according to any one of claims 4 to 8, wherein Z is CO and X is H.

10. The method according to any one of the preceding claims, wherein the catalyst is Ru(H)2(CO)(iPlPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

11. The method according to any one of the preceding claims, wherein the catalyst complex is of formula (IV)P7243PC0012. The method according to any one of claims 4 to 8, wherein Z is CO and X is Cl.

13. The method according to any one of claims 4 to 8, wherein the catalyst is Ru(H)(CO)(CI)(iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

14. The method according to any one of claims 4 to 8, wherein the catalyst is of formula (V)formula (V)15. The method according to any one of the preceding claims, wherein the catalyst is present in an amount between 0.01% and 5% (w / w) based on weight of the ionic liquid.

16. The method according to any one of the preceding claims, wherein the catalyst is present in an amount between 0.01% and 5% (mol%) based on the amount of the ionic liquid.

17. The method according to any one of the preceding claims, wherein the ionic liquid is EMIM-propionate and the catalyst is present in an amount between 0.01% and 5% (mol%) based on the amount of the EMIM-propionate, such as between 0.1% and 1% (mol%) based on the amount of the EMIM-propionate.P7243PC0018. The method according to any one of the preceding claims, wherein the feed stream comprises CO2 and H2, optionally in combination with one or more carrier gasses or trace impurities.

19. The method according to any one of the preceding claims, wherein the feed stream comprises CO2 in a concentration from 1000 ppm to 500.000 ppm, such as from 10.000 ppm to 200.000 ppm.

20. The method according to any one of the preceding claims, wherein the feed stream comprises CO2 in a concentration of less than 50000 ppm.

21. The method according to any one of the preceding claims, wherein the feed stream comprises CO2 in a concentration of less than 5000 ppm.

22. The method according to any one of the preceding claims, wherein the feed stream comprises CO2 in a concentration from 200 to 1000 ppm.

23. The method according to any one of the preceding claims, wherein the CO2 is provided at a pressure between 1 and 40 bar, such as between 1 and 15 bar.

24. The method according to any one of the preceding claims, wherein the hydrogen is provided at a pressure between 1 and 40 bar, such as between 1 and 20 bar.

25. The method according to any one of the preceding claims, wherein the H2 / CO2 ratio is from 50:1 to 1 :

226. The method according to any one of the preceding claims, wherein the H2 / CO2 ratio is 20:1.

27. The method according to any one of the preceding claims, wherein the H2 / CO2 ratio is 5:1.

28. The method according to any one of the preceding claims, wherein the H2 / CO2 ratio is 1 :1.P7243PC0029. The method according to any one of the preceding claims being performed under ambient pressure and / or temperature.

30. The method according to any one of the preceding claims, wherein the feed stream is provided at a total pressure between 1 and 200 bar, such as between 1 and 40 bar, such as between 1 and 20 bar.

31. The method according to any one of the preceding claims, wherein the hydrogenation is carried out at temperature between 25 °C and 200 °C.

32. The method according to any one of the preceding claims, wherein the hydrogenation is carried out at 30(±5) °C, such as 30 °C.

33. The method according to any one of claims 1 to 31 , wherein the hydrogenation is carried out at temperature between 50(±5) °C, such as 50 °C.

34. The method according to any one of the preceding claims, further comprising the addition of at least one additive in an amount which increases at least one of: i) formic acid yield; and / or ii) formic acid production rate, as compared to without addition of said additive under the same reaction conditions.

35. The method according to any one of the preceding claims, wherein the reaction conditions are at least 10:20 bar (CO2:H2), 18h with 0.02 mmol catalyst at 30 °C.

36. The method according to any one of claims 34 to 35, wherein the at least one additive is a Bronsted acid.

37. The method according to any one of claims 34 to 35, wherein the at least one additive is a base, with the proviso that the base is not trioctylamine.P7243PC0038. The method according to any one of claims 34 to 35, wherein the at least one additive is a C3-15 alkylamine, preferably a secondary or tertiary C3-15 alkylamine.

39. The method according to any one of claims 34 to 35, wherein the at least one additive is selected from H3PO4, formic acid, ethanoic acid, propionic acid, dibutylamine, diethylamine, dipropylamine, tributylamine, triethylamine, propylamine, tripropylamine, N,N-diethylethylenediamine, water, methanol, and ethanol.

40. The method according to claim 39, wherein the at least one additive is selected from H3PO4, formic acid, propionic acid, dipropylamine, and triethylamine.41 . The method according to any one of claims 39 to 40, wherein the at least one additive is a mixture of a Bronsted acid and a base, such as a mixture of formic acid and triethylamine.

42. The method according to any one of claims 39 to 41 , wherein the additive is added in an amount ranging from 1 mol% to 300 mol% based on the amount of ionic liquid.

43. The method according to any one of claims 39 to 42, wherein the additive is triethylamine and is added in an amount ranging from 80 mol% to 90 mol% based on the amount of ionic liquid.

44. The method according to any one of claims 39 to 42, wherein the ionic liquid is EMIM-propionate and the additive is triethylamine, preferably 3 mol% to 80 mol%, more preferably 50 mol% triethylamine based on the amount of EMIM- propionate.

45. The method according to any one of claims 39 to 42, wherein the ionic liquid is EMIM-propionate and the additive is methanol, preferably 10 mol% to 50 mol% methanol based on the amount of EMIM-propionate.

46. The method according to any one of claims 34 to 45, wherein the at least one additive is not water.P7243PC0047. A catalytic system for reversible hydrogenation and dehydrogenation of a liquid organic hydrogen carrier (LOHC) pair, the system comprising the ionic liquid EMIM-propionate and the transition metal pincer complex Ru(H)(CO)(CI)( iPrPNP) (iPrPNP: bis(2-(diisopropylphosphaneyl)ethyl)amine).

48. The system according to claim 47, wherein the LOHC pair is FA / CO2.

49. An apparatus for producing electricity comprising a fuel cell and a catalytic system according to any one of claims 47 to 48.

50. Use of the catalytic system according to any one of claims 47 to 48 for providing hydrogen to a fuel cell for producing electricity.

51. Use of a reaction media comprising 1-ethyl-3-methylimidazolium propionate (EMIM-propionate) and homogeneous catalyst Ru(H)(CO)(CI)(iPrPNP) for hydrogenation of CO2 into formic acid (FA).

52. The use according to claim 51 wherein the reaction media does not comprise water.

53. The use of any one of claims 51 to 52 wherein the reaction media further comprises a Bronsted acid and / or Bronsted base.

54. Use of EMIM-propionate as a media for capture of CO2.

55. The use according to claim 54 wherein the CO2 is captured directly from an atmospheric source.

56. The use according to any one of claims 54 to 55, wherein the CO2 is captured under ambient conditions, such as under ambient pressure and / or temperature.

57. The use according to any one of claims 54 to 56, wherein the atmospheric source comprises CO2 in a concentration of less than 5000 ppm.P7243PC0058. The use according to any one of claims 54 to 57, wherein the atmospheric source comprises CO2 in a concentration of 200 ppm to 1000 ppm.

59. The use according to any one of claims 54 to 58, wherein the EMIM-propionate captures and stores at least 60% of the available CO2, such as at least 70%, such as at least 80%.

60. The method according to any one of claims 1 to 46 further comprising a step of formic acid conversion into at least one or methanol or methyl formate.

61. The method according to claim 60, wherein the conversion may be catalytic, or non-catalytic.

62. The method according to any one of claims 1 to 46, wherein the reaction media further comprises a porous solid material, such as wherein the reaction media is a SILP (supported ionic liquid phase), optionally wherein the porous solid material is alumina, titania, silica, carbon, MgO, ceria, zirconia, or mixed oxides, such as MgAI spinel and ZrCe oxides, preferably silica.

63. The method according to claim 62, wherein the catalyst may be provided in an amount corresponding to from 0.1 wt% to 10 wt% of the porous solid material, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 2.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10 wt% or any 0.1 wt% incremental value therein between.

64. The method according to claim 63, wherein the catalyst may be provided in an amount corresponding to from 1 .0 wt% to 5 wt%.

65. The method according to any one of claims 62 to 64, wherein the porous solid material is characterized by a pore volume, such as determined by nitrogen physisorption, from 0.20 cm3 / g to 1.00 cm3 / g, preferably from 0.40 cm3 / g to 0.80 cm3 / g, more preferably from 0.50 cm3 / g to 0.60 cm3 / g.P7243PC0066. The method according to any one of claims 62 to 65, wherein the porous solid material is characterized by a surface area, such as BET surface area, from 70 m2 / g to 300 m2 / g, preferably from 120 m2 / g to 200 m2 / g, more preferably from 140 m2 / g to 180 m2 / g.

67. The method according to any one of claims 62 to 66, wherein the SILP comprises EMIM-propionate, Ru-2 and silica, wherein the silica has a pore volume of 0.55(5) cm3 / g and a BET surface area of 160(5) m2 / g.

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