Methods and Devices for Storage and Release of Hydrogen

Abstract

The invention relates to a process for generating hydrogen, comprising decomposing in a reaction vessel aqueous alkali formate in the presence of a transition metal-containing catalyst system dissolved in one or more organic solvent(s), characterized in that said organic solvent(s) comprise at least one solvent which is water-immiscible, thereby releasing hydrogen and forming bicarbonate in the aqueous phase, and separating the catalyst-containing organic solvent(s) from said bicarbonate. Also disclosed are apparatuses for carrying out hydrogen generation.

Claims

1) A process for generating hydrogen, comprising decomposing in a reaction vessel aqueous alkali formate in the presence of a transition metal-containing catalyst system dissolved in one or more organic solvent(s), characterized in that said organic solvent(s) comprise at least one solvent which is water-immiscible, thereby releasing hydrogen and forming bicarbonate in the aqueous phase, and separating the catalyst-containing organic solvent(s) from said bicarbonate.

2) A process according to claim 1, wherein the alkali formate is KHCO.sub.2.

3) A process according to claim 1, wherein the water-immiscible organic solvent is selected from the group consisting of aliphatic and cyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, esters, ketones, ethers, higher alkanols and carbonate solvents.

4) A process according to claim 1, wherein the catalyst system is dissolved in a mixture of solvents comprising a first organic solvent, which is the water-immiscible solvent, and a second solvent, which is a polar solvent.

5) A process according to claim 4, wherein the second solvent is polar protic organic solvent.

6) A process according to claim 5, wherein the polar protic solvent is selected from the group consisting of C2-C6 alkanols.

7) A process according 6, wherein the catalyst system is dissolved in a mixture of solvents comprising at least a first solvent and a second solvent, characterized in that the first solvent is an aliphatic or cyclic hydrocarbon selected from the group consisting of C6-C10 alkanes, C6-C10 alkenes, cycloalkanes and cycloalkenes, and the second solvent is selected from the group consisting of C2-05 alkanols.

8) A process according 6, wherein the catalyst system is dissolved in a mixture of solvents comprising at least a first solvent and a second solvent, characterized in that the first solvent is an aromatic hydrocarbon selected from the group consisting of alkyl-substituted benzenes, and the second solvent is selected from the group consisting of C2-05 alkanols.

9) A process according 6, wherein the catalyst system is dissolved in a mixture of solvents comprising at least a first solvent and a second solvent, characterized in that the first solvent is a halogenated hydrocarbon selected from the group consisting of halogenated C1-C3 alkanes, C2-C3 alkenes, halogen-substituted cyclic hydrocarbons and halogen-substituted aromatic hydrocarbons, and the second solvent is selected from the group consisting of C2-05 alkanols.

10) A process according 6, wherein the catalyst system is dissolved in a mixture of solvents comprising at least a first solvent and a second solvent, characterized in that the first solvent is selected from the group consisting of water -immiscible esters, water-immiscible ethers, water-immiscible ketones and water-immiscible alkanols having not less than 6 carbon atoms, and the second solvent is selected from the group consisting of C2-05 alkanols.

11) A process according 6, wherein the catalyst system is dissolved in a mixture of solvents comprising at least a first solvent and a second solvent, characterized in that the first solvent is a carbonate liquid selected from the group consisting of (R.sub.1).sub.nXC(O)X(R.sub.2).sub.n where X indicates oxygen, R.sub.1 and R.sub.2, which may be the same or different, are C1-C3 alkyl groups and n is 1, and the second solvent is selected from the group consisting of C2-05 alkanols.

12) A process according to claim 6, wherein the alkanol is selected from the group consisting of ethanol, n-butanol, n-pentanol or a mixture thereof.

13) A process according to claim 1, wherein the transition metal is a platinum-group metal.

14) A process according to claim 13, wherein the platinum-group metal is ruthenium.

15) A process according to claim 13, wherein the catalyst system comprises: a catalyst precursor which is a platinum-group metal complex or a platinum-group metal salt; an additive phosphorous ligand.

16) A process according to claim 15, wherein the catalyst precursor is selected from the group consisting of [RuX.sub.2(arene)].sub.2, wherein arene indicates an aromatic hydrocarbon selected from the group consisting of benzene and alkyl-substituted benzene, and X is halide.

17) A process according to claim 16, wherein the [RuX.sub.2(arene)].sub.2 is [RuX.sub.2(cymene)].sub.2.

18) A process according to claim 15, wherein the additive phosphorous ligand is selected from the group consisting of: 1,1-bis(diphenylphosphino)methane; 1,3 bis(diphenylphosphinomethyl)benzene; triphenylphosphine (P(Ph).sub.3) and tetraphos (PP3).

19) A process according to claim 15, wherein the catalyst system is activated in-situ.

20) A process according to claim 15, wherein the catalyst system is activated ex-situ, by combining in an organic solution the catalyst precursor and the additive phosphorous ligand in the presence of a reducing agent to form a catalytically active form, and supplying said organic solution to the reaction vessel to decompose formate.

21) A process according to claim 1, wherein a surfactant is present in the reaction vessel.

22) A process for generating hydrogen according to claim 1, comprising continuously feeding to the reaction vessel an aqueous MHCO.sub.2 stream and an organic stream in which the metal-containing catalyst system is dissolved in the organic solvent(s), dehydrogenating said MHCO.sub.2 in said reaction vessel, thereby releasing hydrogen and forming bicarbonate (MHCO.sub.3) slurry, continuously discharging from said reaction vessel a reaction mixture consisting of solid bicarbonate and a liquid component, continuously separating the reaction mixture into solid and one or more liquid components, collecting said solid bicarbonate and recycling one or more liquid component(s) to said reactor.

23) A power system comprising at least one fuel cell a hydrogen-generating unit for delivering hydrogen to the fuel cell, wherein said hydrogen-generating unit comprises a tank for holding an aqueous MHCO.sub.2 solution, a tank for holding an organic solution having one or more catalyst components, said tanks and being connected by mens feed lines and to at least one reactor provided with a discharge line having downstream processing devices including separation units coupled to a storage container, wherein recycle line existing separation unit is connected to an inlet opening in said reactor, to recycle liquid stream from said separation unit to said reactor, and wherein said reactor is optionally provided with one or more hydrogen-collecting means in fluid communication with said fuel cell.

24) A power system comprising at least one fuel cell and a hydrogen-generating unit for delivering hydrogen to the fuel cell, wherein said hydrogen-generating unit comprises a tank for holding an aqueous MHCO.sub.2 solution, a tank for holding an organic solution having one or more catalyst components, said tanks and being connected by feed lines and to at least a first reactor and a second reactor each of which is provided with discharge lines and having downstream processing devices including separation units and coupled to storage containers and respectively, wherein recycle lines, existing separation units, respectively, are connected to inlet openings in said reactors and to recycle liquid streams from said separation units to said reactors, and wherein said reactors and are optionally provided with one or more hydrogen-collecting means in fluid communication with said fuel cell, wherein an array of valves is further incorporated into the apparatus, to control the flow of feed streams to either reactor or.

25) (canceled)

26) (canceled)

27) (canceled)

Description

IN THE DRAWINGS

[0091] FIG. 1 shows the solubility curves of potassium bicarbonate and potassium formate.

[0092] FIG. 2 schematically illustrates an apparatus for carrying out the dehydrogenation reaction.

[0093] FIG. 3 schematically illustrates an apparatus for carrying out the dehydrogenation reaction in a continuous mode of operation, where the separation of the reaction mixture into its components is achieved with the aid of hydro cyclone and a centrifugal separator.

[0094] FIG. 4 schematically illustrates an apparatus for carrying out the dehydrogenation reaction in a continuous mode of operation, where the separation of the reaction mixture into its components is achieved with the aid of hydro cyclone and a drum filter.

[0095] FIG. 5 schematically illustrates an apparatus for carrying out the dehydrogenation reaction in a continuous mode of operation, where the separation of the reaction mixture into its components is achieved with the aid of hydro cyclone alone.

[0096] FIG. 6 schematically illustrates an apparatus for carrying out the hydrogenation reaction of the invention.

[0097] FIG. 7 schematically illustrates an apparatus for carrying out the hydrogenation reaction in a continuous mode of operation, employing hydro cyclone separation.

[0098] FIG. 8 illustrates an apparatus for carrying out the hydrogenation reaction in a batch or continuous mode of operation, with the aid of hydro cyclone separation and filtration/centrifugal separation.

[0099] FIG. 9 provides photos showing the solidification of the reaction mixture under prior art conditions (A) as opposed to the fluid, easily separable reaction mixture obtained according to the invention (B).

EXAMPLES

Preparation 1

[{RuCl.SUB.2.(cymene)}.SUB.2.]

[0100] A solution of hydrated ruthenium trichloride (2 g, approx. 7.7 mole) in 100 mL ethanol is treated with 10 mL -phellandrene and heated under reflux in a 150-mL, round-bottomed flask for 4 hours under nitrogen atmosphere. The solution is allowed to cool to room temperature, and the red-brown, microcrystalline product is filtered off. Additional product is obtained by evaporating the orange-yellow fitrate under reduced pressure to approximately half-volume and refrigerating overnight.

Preparation 2

Supported Palladium Catalyst

[0101] Palladium (II) nitrate dihydrate (0.096 mmol, Sigma 76070) was dissolved in water (1 L). Activated carbon (Sigma C-3345) was heated to 200 C. for 1 hour. The treated activated carbon (25 g in order to get 0.4% Pd/C) was added into the palladium solution and stirring was activated to 700 rpm for 1 hour. Then an aqueous solution of potassium formate (0.081 g in 200 ml of water) that was used as a reduction agent was added dropwise for 30 minutes at 25 C. (molar ratio between palladium and reduction agent is 10:1, total concentration of formate in the vessel was 0.008M). Following that the mixture was left while stirring continued at room temperature for 24 hours. After 24 hours the mixture was filtered, washed thoroughly with deionized water and left to dry at room temperature.

Examples 1-7

Dehydrogenation of Aqueous Potassium Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Single Organic Solvent

[0102] Dppm in an organic solvent was heated at 60 C. during 15 min, followed by the addition of aqueous potassium formate solution with a concentration 15.7 M. The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0103] The experimental details [organic solvent used, volume of organic solvent (V.sub.solvent) volume of KHCO.sub.2 solution (V.sub.KHCO2) and number of moles of ruthenium metal source added (n.sub.Ru); the molar ratio Ru:DPPM was 1:3 in all of these examples] are set out in Table 1, along with the performance of the catalyst measured after one hour.

TABLE-US-00004 TABLE 1 V.sub.solvent V.sub.KHCO2 n.sub.Ru TON Example solvent (ml) (ml) (mmol) (1 h) 1 dichloroethane 2 18 0.08 46.04 2 trichloroethane 2 18 0.08 56.27 3 2-octanol 2 18 0.08 51.15 4 trimethylhexanol 2 18 0.08 71.62 5 ethylHexanol 10 10 0.2 51.15 6 butylacetate 10 10 0.2 20.46 7 hexanol 10 10 0.2 104.35

Examples 8-10

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents Consisting of Aliphatic Solvent and Alkanol

[0104] Dppm (0.6 mmol) in a 10 ml mixture of organic solvents (S1:S2) was heated at 60 C. during 15 min, followed by the addition of 10 ml of aqueous potassium formate solution (with a concentration 15.7 M; 0.16 mol). 0.2 mmol The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0105] The experimental details [mixture of organic solvents used (S1:S2) and their volumetric ratio (V.sub.S1:V.sub.S2)] are set out in Table 2, along with the performance of the catalyst measured after one hour.

TABLE-US-00005 TABLE 2 Example S1:S2 V.sub.S1:V.sub.S2 TON (1 h) 8 2,2,4-trimethylpentane:ethanol 1:1 14.94 9 Heptane:ethanol 3:1 81.85 10 Methylcyclohexane:ethanol 1:1 35.40

Examples 11- 14

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents Consisting of Aromatic Solvent and Alkanol

[0106] Dppm in a solvent mixture (S1:S2) was heated at 60 C. during 15 min, followed by the addition of aqueous potassium formate solution with a concentration 15.7 M. The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0107] The experimental details (mixture of organic solvents used (S1:S2), the volumes of the two solvents (V.sub.S1 and V.sub.S2, respectively), volume of KHCO.sub.2 solution (V.sub.KHCO2) and number of moles of ruthenium metal source added (n.sub.Ru); the molar ratio Ru:DPPM was 1:3 in all of these examples) are set out in Table 3, along with the performance of the catalyst measured after one hour.

TABLE-US-00006 TABLE 3 V.sub.KHCO2 n.sub.Ru Example S1:S2 V.sub.S1 (ml):V.sub.S2 (ml) (ml) (mmol) TON (1 h) 11 Xylene:butanol 5:5 2.5 0.04 133 12 Mesitylene:butanol 0.6:1.4 18 0.08 153.46 13 Cymene:butanol 4:6 10 0.2 151.42 14 Toluene:ethanol 7.5:2.5 10 0.2 110.49

Examples 15-18

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents Consisting of Halogenated Hydrocarbon and Alkanol

[0108] Dppm in a solvent mixture (S1:S2) was heated at 60 C. during 15 min, followed by the addition of aqueous potassium formate solution with a concentration 15.7 M. The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0109] The experimental details [mixture of organic solvents used (S1:S2), the volumes of the two solvents (V.sub.S1 and V.sub.S2, respectively), volume of KHCO.sub.2 solution (V.sub.KHCO2) and number of moles of ruthenium metal source added (n.sub.Ru); the molar ratio Ru:DPPM was 1:3 in all of these examples] are set out in Table 4, along with the performance of the catalyst measured after one hour.

TABLE-US-00007 TABLE 4 V.sub.KHCO2 n.sub.Ru Ex. S1:S2 V.sub.S1 (ml):V.sub.S2 (ml) (ml) (mmol) TON (1 h) 15 tetrachlorethylene:butanol 0.8:1.2 18 0.04 93.98 16 trichlorethylene:butanol 1:1 20 0.08 51.15 17 trichloroethane:butanol 1:1 20 0.16 66.50 18 1,2 dichloroethane:ethanol 15:5 5 0.01 122.77

Examples 19-22

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents Consisting of Polar Aprotic Solvent and Alkanol

[0110] Dppm in a solvent mixture (S1:S2) was heated at 60 C. during 15 min, followed by the addition of aqueous potassium formate solution with a concentration 15.7 M. The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0111] The experimental details [mixture of organic solvents used (S1:S2), volumes of the two solvents (V.sub.S1 and V.sub.S2, respectively), volume of KHCO.sub.2 solution (V.sub.KHCO2) and number of moles of ruthenium metal source added (n.sub.Ru); the molar ratio Ru:DPPM was 1:3 in all of these examples] are set out in Table 5, along with the performance of the catalyst measured after one hour.

TABLE-US-00008 TABLE 5 V.sub.KHCO2 n.sub.Ru Ex. S1:S2 V.sub.S1 (ml):V.sub.S2 (ml) (ml) (mmol) TON (1 h) 19 Ethyl acetate:butanol 1:1 20 0.8 30.69 20 methylethylketone:butanol 1:1 20 0.16 51.15 21 anisole:ethanol 3.75:1.25 15 0.2 104.42 22 butylacetate:butanol 5:5 10 0.2 102.31

Examples 23-24

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents Consisting of a Carbonate Solvent and Alkanol

[0112] Dppm in 10 ml of a solvent mixture (S1:S2) was heated at 60 C. during 15 min, followed by the addition of of aqueous potassium formate solution with a concentration 14 M. The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0113] The experimental details [mixture of organic solvents used (S1:S2), volumes of the two solvents (V.sub.S1 and V.sub.S2, respectively), volume of KHCO.sub.2 solution (V.sub.KHCO2) and number of moles of ruthenium metal source added (n.sub.Ru); the molar ratio Ru:DPPM was 1:3 in all of these examples] are set out in Table 6, along with the performance of the catalyst measured after one hour and three hours.

TABLE-US-00009 TABLE 6 V.sub.KHCO2 n.sub.Ru TON Ex. S1:S2 V.sub.S1 (ml):V.sub.S2 (ml) (ml) (mol) (1 h); (3 h) 23 Dimethylcarbonate:butanol 6.0:4.0 1.46 10 204.6; 532.0 24 Diethylcarbonate:ethanol 7.5:2.5 2.96 20 522.1; 1044.2

Examples 25-27

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture Consisting of Eiethyl Carbonate and Ethanol

[0114] Dppm (30.0 mol) in a mixture consisting of diethyl carbonate and ethanol (S1:S2) was heated at 60.sup.0C during 15 min, followed by the addition of aqueous alkali formate solution. 10 mol of the ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate.

[0115] The experimental details [volumes of the two organic solvents (V.sub.S1 and V.sub.S2, respectively), alkali formate solution (MHCO.sub.2), its concentration (C.sub.MHVO2) and volume (V.sub.MHCO2)] are set out in Table 7, along with the performance of the catalyst measured after one hour.

TABLE-US-00010 TABLE 7 V.sub.MHCO2 TON Example V.sub.S1 V.sub.S2 MHCO.sub.2 C.sub.MHCO2 (M) (ml) (1 h) 25 16 4 NaHCO.sub.2 4 5 409.2 26 15 5 KHCO.sub.2 4 2 204.6 27 7.5 2.5 KHCO.sub.2 10 2.5 1253.0

Examples 28-29 (of the Invention) and 30 (Comparative)

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Dissolved in a Mixture of Solvents in the Presence of Formic Acid

[0116] In the next set of Examples, the effect of addition of formic acid on the dehydrogenation of alkali formate at different temperatures was investigated.

[0117] Dppm (75 pmol) in 10 ml of a solvent mixture consisting of tetrachloroethylene and ethanol (1:1 volumetric ratio) was heated at a fixed temperature during 15 min, followed by the addition of aqueous potassium formate solution with a concentration 15.7 M and 0.7 ml of formic acid (illustrated in Examples 28 and 29; Example 30 is a comparative example, devoid of potassium formate). Then, 98 pmol of the ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma (Ru:L=1:2) was introduced into the reaction mixture at the fixed temperature. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0118] The experimental details [Reaction temperature] along with the performance of the catalyst measured after one hour and three hours are set forth in Table 8.

TABLE-US-00011 TABLE 8 TON Example T ( C.) (1 h); (3 h) 28 40 31.3; 292.4 29 60 563.9; 835.4 30 60 41.8; 62.7

Examples 31-33

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents in the Presence of a Surfactant

[0119] In the next set of Examples, the effect of addition of surfactant(s) on the dehydrogenation of alkali formate was investigated. The surfactant was added to the solvents mixture. When a pair of surfactants was tested, the surfactants were added separately to the organic and aqueous components.

[0120] Dppm in 10 ml of a solvent mixture (S1:S2), which was previously mixed with a surfactant A, was heated at 60 C. during 15 min, followed by the addition of 10 ml aqueous potassium formate solution with a concentration 15.7 M, to which surfactant B was previously charged.

[0121] Then, ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0122] The experimental details [mixture of organic solvents used (S1:S2) and the volumetric ratio between the two solvents, surfactant A added to the organic phase; surfactant B added to the aqueous solution; number of moles of ruthenium metal source added (n.sub.Ru); the molar ratio Ru:DPPM was 1:3 in all of these examples] are set out in Table 9, along with the performance of the catalyst measured after one hour.

TABLE-US-00012 TABLE 9 Surfactant Surfactant A B n.sub.Ru TON Ex. S1:S2 (% wt)* (% wt)** (mol) (1 h) 31 Tetrachloroethylene:butanol Aliquat 98 125.3 (10%) 32 Tetrachloroethylene:butanol TBACl 98 167.1 (10%) 33 mesitylene:butanol Span 80 Tween 198 250.6 (1%) 80 (9%) *% by weight based on the organic phase **% by weight based on the organic phase

Example 34

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents

[0123] Dppm (44.09 mmol) in a mixture consisting of 375 ml of mesitylene and ethanol (1:1 volumetric ratio) was heated at 60 C. during 15 min, followed by the addition of 375 ml of aqueous alkali formate solution. 14.69 mmol of the ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a mechanical stirrer (1400 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate. The number TON after 15 min was evaluated at 83.57.

Examples 35-65

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Phosphorous Ligand Dissolved in a Mixture of Solvents Under Different Conditions

[0124] The data presented in Table 10 illustrate the efficacy of the dehydrogenation reaction under various conditions. The data were generated during experiments carried out according to the typical procedures set forth in previous examples.

TABLE-US-00013 TABLE 10 V.sub.KHCO2 n.sub.Ru TON Ex. S1:S2 V.sub.S1 (ml); V.sub.S2 (ml) (ml) (mol) Ru:L (1 h) 35 Anisole:ethanol 6; 4 10 196.0 1:3 302.8 36 Anisole:butanol 5; 5 10 196.0 1:3 156.6 37 Anisole:butanol 5; 5 10 196.0 1:2 250.6 38 Anisole:pentanol 4; 6 10 196.0 1:3 271.5 39 Anisole:hexanol 2; 8 10 196.0 1:3 168.3 40 MEK:ethanol 6; 4 10 200.0 1:3 145.3 41 MEK:ethanol 15; 5 5 10.0 1:3 409.2 42 MEK:butanol 1; 1 20 80.0 1:3 133.0 43 MEK:butanol 5; 5 10 200.0 1:3 87.0 44 Ethyl acetate:ethanol 15; 5 5 10.0 1:3 532.0 45 Ethyl acetate:butanol 1; 1 20 160.0 1:3 70.34 46 Mesitylene:ethanol 5; 5 10 196.0 1:2 313.3 47 Mesitylene:butanol 4; 6 10 196.0 1:2 167.1 48 Mesitylene:pentanol 3; 7 10 196.0 1:3 167.1 49 Mesitylene:hexanol 3; 7 10 196.0 1:3 114.86 50 Mesitylene:ethylhexanol 2; 8 10 200.0 1:3 24.55 51 Xylene:ethanol 15; 5 5 10.0 1:3 409.2 52 Xylene:pentanol 7; 3 2.5 40.0 1:3 51.2 53 Xylene:pentanol 5; 5 2.5 40.0 1:3 194.4 54 Dichloroethane:butanol 1; 1 20 48.0 1:3 149.2 55 Trichloroethane:ethanol 15; 5 5 10.0 1:3 204.6 56 Trichloroethane:butanol 1; 1 20 80.0 1:3 112.5 57 Trichloroethylene:butanol 1; 1 20 160.0 1:3 102.3 58 Tetrachloroethylene:ethanol 7; 3 10 196.0 1:3 177.5 59 Tetrachloroethylene:butanol 4; 6 2.5 39.2 1:3 86.7 60 Tetrachloroethylene:butanol 8; 8 4 313.5 1:2 126.6 61 Tetrachloroethylene:pentanol 0.8; 1.2 18 39.2 1:3 229.7 62 Dimethyl carbonate:ethanol 16; 4 5 10.0 1:3 1677.9 63 Dimethyl carbonate:butanol 1; 1 20 160.0 1:3 117.7 64 Diethyl carbonate:ethanol 15; 5 10 10.0 1:3 2250.8 65 Diethyl carbonate:butanol 5; 5 2.5 19.6 1:3 835.4

Examples 66-72

Preparation of Storable Metal-solution Catalysts and their use for Dehydrogenating Formate

[0125] In the next set of Examples, several active catalysts (desinated M1-M7) were prepared in advance, stored for a period of time of about one day to fifteen days, and then tested in the dehydrogenation reaction.

[0126] a) Preparation Metal-solution Catalytic M1:

[0127] Dppm (0.6mmol) in 10 ml of anisole:butanol (1:1) mixture was heated at 60 C. during 15 min, followed by the addition of 10 ml of aqueous potassium formate solution (15.7 M PF; 0.16 mol). 0.2 mmol of the ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, (Ru:L=1:3) was introduced into the preparation mixture at 60 C. After 10 minutes of stirring with a magnetic stirrer (1500 rpm), the catalytic organic liquid phase (M1) was separated easily from the aqueous phase and stoked under argon.

[0128] b) Preparation Metal-solution Catalytic M2 at 80 C.

[0129] Dppm (0.6mmol) in 10 ml of mesitylene:butanol (2:3) mixture was heated at 80 C. during 15 min, followed by the addition of 10 ml of aqueous potassium formate solution (15.7 M PF; 0.16 mol). 0.2 mmol of the ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, (Ru:L=1:3) was introduced into the preparation mixture at 80 C. After 5 minutes of stirring with a magnetic stirrer (1500 rpm), the catalytic organic liquid phase (M2) was separated easily from the aqueous phase and stoked under argon.

[0130] c) Preparation Metal-solution Catalytic M3, M4, M5, M6 and M7 with Different Reducing Agents:

[0131] Dppm (0.12mmol) in 2 ml of tetrachloroethylene:butanol (1:1) mixture was heated at 60 C. during 15 min, followed by the addition of 0.5 ml of aqueous reducing solution (containing 4mmol of reducer agent: sodium borohydride for M3, formic acid for M4, potassium citrate for M5 or citric acid for M6) or 2.5 ml of aqueous potassium formate solution (15.7 M PF; 4mmol) for M7. 40 pmol of the ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, (Ru:L=1:3) was introduced into the preparation mixture at 60 C. After 30 minutes of stirring with a magnetic stirrer (1500 rpm), the catalytic preparation mixture is cooled and stoked under argon.

[0132] The catalysts M1-M7 were stored (see storage periods in the Table 11 below) and used in the dehydrogenation reaction according to the following typical procedure. The metal-containing solution was heated at 60 C. during 15 min, followed by the addition of aqueous potassium formate solution (15.7 M) heated previously at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started and the gas evolved was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate.

[0133] The experimental details and the performance of the catalysts are set out in Table 11.

TABLE-US-00014 TABLE 11 Storage period V.sub.catalyst TON Example catalyst (days) (ml) V.sub.KHCO2 (ml) (1 h) 66 M1 1 2 18 313.3 67 M2 15 10 10 177.5 68 M3 1 2 4.5 208.8 69 M4 1 2 4.5 261.1 70 M5 1 2 4.5 104.4 71 M6 7 2 4.5 261.1 72 M7 7 2 4.75 417.7

Examples 73-75

Dehydrogenation of Aqueous Alkali Formate with the Aid of Various Metal Catalysts Dissolved in a Mixture Consisting of Diethyl Carbonate and Ethanol

[0134] Dppm (0.4mmol) in 10 ml of tetrachloroethylene : butanol (1:1) mixture was heated at 60 C. during 15 min, followed by the addition of 10 ml of aqueous potassium formate solution (15.7 M PF; 0.16 mol). 0.2 mmol of the metal source, [IrCl(CO) [P(Ph).sub.3].sub.2], [RhCl[P(Ph).sub.3].sub.3] or[Pd(OAc).sub.2] commercially available from Sigma, (Ru:L=1:3) was introduced into the reaction mixture at 60 C., which was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry. The performance of the catalysts was measured after twenty four hours and is reported in Table 12.

TABLE-US-00015 TABLE 12 Example metal source TON (24 h) 73 IrCl(CO)[P(Ph).sub.3].sub.2 46.0 74 RhCl[P(Ph).sub.3].sub.3 35.8 75 Pd(OAc).sub.2 69.6

Examples 76-79

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalysts Prepared from Various Ruthenium Sources and Dissolved in a Solvent Mixture

[0135] In this set of examples, different ruthenium compounds were used as the metal source. The ligand employed in all experiments was the same (DPPM). The ruthenium sources tested were:

[0136] [RuCl.sub.3] (R1); [RuCl.sub.2[P(Ph).sub.3].sub.3] (R2); [{RuCl.sub.2(benzene)}.sub.2] (R3); and [{RuCl.sub.2(Hexamethylbenzene)}.sub.2] (R4), all commercially available from Sigma.

[0137] Dppm in solvent mixture (S1:S2) was heated at 60 C. during 15 min, followed by the addition of aqueous alkali formate solution. The ruthenium source was introduced into the reaction mixture at 60 C. ((Ru:L=1:3). The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0138] The experimental details and performance of the catalysts, which was measured after twenty four hours, are tabulated in Table 13 (DMC=dimethyl carbonate; DEC=diethyl carbonate).

TABLE-US-00016 TABLE 13 Ru n.sub.Ru MHCO.sub.2 V.sub.MHCO2 TON Ex. source (mol) S1:S2 V.sub.S1 (ml):V.sub.S2 (ml) C.sub.MHCO2 (M) (ml) (1 h) 76 R1 25 DMC:ethanol 15:5 NaHCO2 5 81.85 4M 77 R2 25 DMC:ethanol 15:5 KHCO2 5 204.6 4M 78 R3 10 DEC:ethanol 16:4 NaHCO2 5 732.6 4M 79 R4 214 Mesitylene:butanol 4:6 KHCO2 10 430.5 16M

Examples 80-82

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalysts Dissolved in a Solvent Mixture Consisting of Tetrachloroethylene and Butanol (in the Absence of Additive Ligand)

[0139] Tetrachloroethylene:butanol (1:1) mixture was heated at 60 C. during 15 min, followed by the addition of aqueous potassium formate solution (15.7M). The ruthenium source, [Milstein's catalyst] (R5), [Ru(COD)Cl.sub.2]n] (R6), or [Ru-MACHO] (R7) commercially available from Sigma, was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the evolved gases were collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0140] The experimental details [volume of the solvent mixture (V.sub.S1+S2), volume of KHCO.sub.2 solution (V.sub.KHCO2) and number of moles of ruthenium metal source added (n.sub.Ru) are set out in Table 14, along with the performance of the catalyst measured after three hours.

TABLE-US-00017 TABLE 14 Ru TON Ex. source n.sub.Ru (mmol) V.sub.S1+S2 (ml) V.sub.MHCO2 (ml) (3 h) 80 R5 0.2 15 5 30.7 81 R6 0.2 15 5 61.4 82 R7 0.32 16 4 188.6

Examples 83-86

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Precursor and Various Additive Ligands Dissolved in a Solvent Mixture

[0141] In this set of examples, the metal source used was [RuCl.sub.2(cymene)].sub.2 in all experiments, but the ligands were changed. The following ligands were tested: 1,3 bis(diphenylphosphinomethyl)benzene (L1); triphenylphosphine (P(Ph).sub.3) (L2); (1S,2S)-p-Tosyl-1,2-diphenylethylenediamine (tsdpen) (L3) or tetraphos (PP3) (L4).

[0142] The ligand was heated at 60 C. during 15 min in tetrachloroethylene: butanol (1:1) mixture, followed by the addition of aqueous potassium formate solution (15.7M). The ruthenium source, [{RuCl.sub.2(cymene)}.sub.2] commercially available from Sigma, (Ru:L=1:2), was introduced into the reaction mixture at 60 C. The reaction mixture was stirred with a magnetic stirrer (1500 rpm). Gas evolution then started, and the gas was collected with an automatic gas burette. At the end of the reaction, the organic phase was separated easily from the bicarbonate slurry.

[0143] The experimental details along with the performance of the catalyst measured after one hour and three hours are set forth in Table 15.

TABLE-US-00018 TABLE 15 n.sub.Ru V.sub.MHCO2 TON Example ligand (mmol) V.sub.S1+S2 (ml) (ml) (1 h) (3 h) 83 L1 25 10 10 10.2 35.8 84 L2 25 10 10 4.1 57.3 85 L3 10 10 4 26.9 99.1 86 L4 214 10 4 7.7 35.2

Examples 87-89

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Dissolved in Diethyl Carbonate

[0144] Dppm (30.0 pmol) in 20 ml of diethyl carbonate (in the presence of some ethanol) was heated at 60 C. during 15 min, followed by the addition of aqueous alkali formate solution (4M; 20 mmol dissolved in 5 ml of water). 5 pmol of the Ru source, [{RuCl.sub.2(cymene)}.sub.2] of Preparation 1, or [{RuCl.sub.2(benzene)}.sub.2] commercially available from Sigma, was introduced into the reaction mixture at 60 C., which was stirred with a magnetic stirrer (1000 rpm). Gas evolution then started, and the evolved gases were collected with an automatic gas burette.

[0145] At the end of the reaction, the organic phase was separated easily from the bicarbonate. Notably, the reaction is devoid of CO.sub.2 formation.

[0146] The experimental details, amount of hydrogen gas generated (measured after three hours of reaction) and the performance of the catalysts are set out in Table 16.

TABLE-US-00019 TABLE 16 MHCO.sub.2 V.sub.H2 TOF TON Example solution Ru complex source (ml) (min.sup.1) (3 h) 87 NaHCO.sub.2 [{RuCl.sub.2(cymene)}.sub.2] 350 11.94 1432.31 88 NaHCO.sub.2 [{RuCl.sub.2(benzene)}.sub.2] 250 10.91 1023.08 89 KHCO.sub.2 [{RuCl.sub.2(cymene)}.sub.2] 260 6.82 1064.00

Example 90 (comparative)

Dehydrogenation of Aqueous Alkali Formate with the Aid of Ruthenium Catalyst Dissolved in DMF According to Angew.

Chem. Int. Ed. 50, p. 6411-6414(2011)

[0147] Dppm (30pmol) in 120 ml of DMF was heated at 60 C. during 15 min, followed by the addition of 5 ml of aqueous potassium formate solution (4 M; 20mmol). 10 pmol of the ruthenium source, [{RuCl.sub.2(benzene)}.sub.2], commercially available from Sigma, (Ru:L=1:3) was introduced into the reaction mixture at 60 C., which was stirred with a magnetic stirrer (1000 rpm). Gas evolution then started, and the evolved gases were collected with an automatic gas burette.

[0148] Shortly after set off of the reaction, the formed non-soluble product, bicarbonate, precipitates and causes the reaction mixture to solidify. A white solid is formed which traps the catalyst and the catalytic reaction. A photo of the white solid mixture formed during the reaction is shown in FIG. 9A. For the purpose of comparison, a photo showing the fluid, easily separable reaction mixture (B) obtained according to a typical procedure set forth in the previous examples, is also provided (using [{RuCl.sub.2(cymene)}.sub.2] in diethyl carbonate: ethanol]. The two separable phases in the reaction mixture (B) are readily visible: the upper yellow layer consists of the organic catalytic system and the lower layer is the aqueous formate phase with the white bicarbonate precipitate.