MATERIALS COMPRISING CARBON-EMBEDDED COBALT NANOPARTICLES, PROCESSES FOR THEIR MANUFACTURE, AND USE AS HETEROGENEOUS CATALYSTS

Abstract

The present invention relates to catalytically active material, comprising grains of non-graphitizing carbon with cobalt nanoparticles dispersed therein, wherein d.sub.p, the average diameter of cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 1 nm to 20 nm, D, the average distance between cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 2 nm to 150 nm, and ω, the combined total mass fraction of metal in the non-graphitizing carbon grains, is in the range of 30 wt % to 70 wt % of the total mass of the non-graphitizing carbon grains, and wherein d.sub.p, D and ω conform to the following relation: 4.5 d.sub.p/ω>D≥0.25 d.sub.p/ω. The present invention, further, relates to a process for the manufacture of material according to the invention, as well as its use as a catalyst.

Claims

1-14. (canceled)

15. Catalytically active material, comprising grains of non-graphitizing carbon with cobalt nanoparticles dispersed therein, wherein: d.sub.p, the average diameter of cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 1 nm to 20 nm; D, the average distance between cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 2 nm to 150 nm; and ω, the combined total mass fraction of metal in the non-graphitizing carbon grains, is in the range of 30 wt % to 70 wt % of the total mass of the non-graphitizing carbon grains; wherein d.sub.p and D are measured by TGZ-TEM, and d.sub.p, D and ω conform to the following relation: 4.5 d.sub.p/ω>D≥0.25 d.sub.p/ω.

16. The catalytically active material of claim 15, wherein the non-graphitizing carbon grains exhibit the following particle size distribution: d10=5 μm, d50=40 μm, and d90=150 μm.

17. The catalytically active material of claim 15, wherein the total mass fraction of nitrogen in the non-graphitizing carbon grains is less than 1 wt % of the total mass of the non-graphitizing carbon grains.

18. The catalytically active material of claim 15, wherein d.sub.p is in the range of 1 nm to 10 nm.

19. The catalytically active material of claim 15, wherein d.sub.p is in the range of 2 nm to 6 nm.

20. The catalytically active material of claim 15, wherein the catalytically active material has been doped with a dopant metal selected from the group consisting of: Mn; Cu; and mixtures thereof, and the non-graphitizing carbon grains exhibit a molar ratio RDM=n(cobalt):n(dopant metal) in the range of 2 to 15.

21. The catalytically active material of claim 15, wherein the total mass fraction of Cu is less than 10.sup.−4 wt % of the total mass of the non-graphitizing carbon grains.

22. The catalytically active material of claim 16, wherein the total mass fraction of nitrogen in the non-graphitizing carbon grains is less than 1 wt % of the total mass of the non-graphitizing carbon grains.

23. The catalytically active material of claim 16, wherein d.sub.p is in the range of 1 nm to 10 nm.

24. The catalytically active material of claim 16, wherein the material has been doped with a dopant metal selected from the group consisting of: Mn; Cu; and mixtures thereof, and the non-graphitizing carbon grains exhibit a molar ratio RDM=n(cobalt):n(dopant metal) in the range of 2 to 15.

25. The catalytically active material of claim 16, wherein the total mass fraction of Cu is less than 10.sup.−4 wt % of the total mass of the non-graphitizing carbon grains.

26. The catalytically active material of claim 17, wherein the material has been doped with a dopant metal selected from the group consisting of: Mn; Cu; and mixtures thereof, and the non-graphitizing carbon grains exhibit a molar ratio RDM=n(cobalt):n(dopant metal) in the range of 2 to 15.

27. The catalytically active material of claim 26, wherein d.sub.p is in the range of 1 nm to 10 nm.

28. A process for making the catalytically active material of claim 15, comprising the following steps: (a) providing an aqueous solution comprising a metal precursor and an organic carbon source, wherein: the metal precursor comprises one or more organic, at least partially water soluble, salts of cobalt; and the organic carbon source comprises one or more saturated, aliphatic di-, tri-, or polycarboxylic acids; (b) spray drying or freeze drying the aqueous solution of the metal precursor and the organic carbon source, and thus obtaining intermediate product P; and (c) thermo-treating intermediate product P at a temperature in the range from 200° C. to 380° C.

29. The process of claim 28, wherein the organic carbon source is selected from the group consisting of: malonic acid; tartaric acid; citric acid; and mixtures thereof.

30. The process of claims 28, wherein intermediate product P is thermo-treated at a temperature in the range from 255° C. to 375° C. for 1 to 4 hours.

31. The process of claim 28, wherein an intermediate product P is thermo-treated at a temperature in the range from 300° C. to 350° C. for 1 to 4 hours.

32. A chemical reaction comprising the catalytically active material of claim 15, as a catalyst.

33. The chemical reaction of claim 32, wherein the reaction is a hydrogenation of organic compounds; a reductive amination of carbonyl compounds; or a hydroformylation of organic compounds.

34. The chemical reaction of 32, comprising reacting carbon monoxide, carbon dioxide or mixtures thereof, with hydrogen, to form alcohols, alkenes, alkanes or mixtures thereof.

Description

FIGURE LEGENDS

[0099] FIG. 1:

[0100] TEM Image of carbon embedded cobalt nanoparticles (Cat. 1b) according to the invention.

EXAMPLES

Examples 1 a,b

Preparation of Carbon Embedded Co-Nanoparticles

[0101] Carbon embedded Co-nanoparticles were prepared by dissolving 14.4 g citric acid (puriss, Sigma Aldrich) in 75 mL of deionized water under constant stirring at room temperature. In a second beaker 18.7 g Cobalt(II)-acetate tetrahydrate ((CH.sub.3COO).sub.2Co*4 H.sub.2O, Sigma Aldrich) was dissolved in 75 mL of deionized water under constant stirring at room temperature. The Cobalt-acetate solution was slowly added to the citric acid solution and stirred for another 30 min at room temperature. The resultant solution was spray dried using a conventional mini spray dryer (Büchi, Mini Spray Dryer B-290) with constant inlet temperature of 220° C., outlet temperature of 120° C. and 20% pump speed. The obtained powder was split into two fractions with identical mass for the final thermo-treatment.

[0102] The first sample was thermo-treated in a tubular furnace under nitrogen atmosphere, with a 180 min ramp to 300° C., where temperature was maintained for another 4 h followed by natural cooling down. The resultant catalyst powder was labeled Cat. 1a.

[0103] The second sample was thermo-treated in a similar fashion under nitrogen atmosphere. The sample was heated up to 350° C. within 180 min where temperature was maintained for 4 h followed by natural cool down. The resultant catalyst powder was labeled Cat. 1 b.

[0104] The materials exhibit the following characteristics which were determined by XRF (X-ray fluorescence) and TGZ analysis using a calibrated Hitachi H-7500 field transmission electron microscope operated at 100 keV, equipped with a CCD-Camera:

TABLE-US-00001 ID d.sub.p ω D 1a 3.0 nm 0.54 7 nm 1b 3.5 nm 0.59 6 nm

Example 2

Preparation of Carbon Embedded Co—Cu-Nanoparticles

[0105] Carbon embedded Co-Cu-nanoparticles were prepared by dissolving 19.4 g citric acid (puriss, Sigma Aldrich) in 100 mL of deionized water under constant stirring at room temperature. In a second beaker 19.9 g Cobalt(II)-acetate tetrahydrate ((CH.sub.3COO).sub.2Co*4 H.sub.2O, Sigma Aldrich) and 3.9 g Cu(II)-acetate-Monohydrate ((CH.sub.3COO).sub.2Cu*H.sub.2O, Alfa Aesar) were dissolved in 100 mL of deionized water under constant stirring at room temperature. The Cobalt-Copper-solution was slowly added to the citric acid solution and stirred for another 30 min at room temperature. The resultant solution was spray dried using a conventional mini spray dryer (Büchi, Mini Spray Dryer B-290) with constant inlet temperature of 220° C., outlet temperature of 130° C. and 30% pump speed. The obtained powder was thermo-treated in a tubular furnace under nitrogen atmosphere, with a 180 min ramp to 350° C., where temperature was maintained for another 4 h followed by natural cooling down. The resultant catalyst powder was labeled Cat. 2.

[0106] The materials exhibit the following characteristics which were determined by XRF (X-ray fluorescence) and TGZ analysis using a calibrated Hitachi H-7500 field transmission electron microscope operated at 100 keV, equipped with a CCD-Camera:

TABLE-US-00002 ID d.sub.p ω D 2 5.0 nm 0.65 9 nm

Examples 3 a,b

Preparation of Carbon Embedded Co—Mn-Nanoparticles

[0107] Carbon embedded Co-Mn-nanoparticles were prepared by dissolving 14.4 g citric acid (puriss,

[0108] Sigma Aldrich) in 75 mL of deionized water under constant stirring at room temperature. In a second beaker 18.7 g Cobalt(II)-acetate tetrahydrate ((CH.sub.3COO).sub.2Co*4 H.sub.2O, Sigma Aldrich) and 1.5 g Mn(II)-acetate tetrahydrate (Mn(CH.sub.3COO)2*4 H.sub.2O, Sigma Aldrich) were dissolved in 75 mL of deionized water under constant stirring at room temperature. The Cobalt-Manganese-solution was slowly added to the citric acid solution and stirred for another 30 min at room temperature. The resultant solution was spray dried using a conventional mini spray dryer (Büchi, Mini Spray Dryer B-290) with constant inlet temperature of 220° C., outlet temperature of 125° C. and 25% pump speed. The resultant powder was split into two fractions with identical mass for the final thermo-treatment.

[0109] The first sample was thermo-treated in a muffle furnace under nitrogen atmosphere, with a 180 min ramp to 300° C., where temperature was maintained for another 4 h followed by natural cooling down. The resultant catalyst powder was labeled Cat. 3a.

[0110] The second sample was thermo-treated in a similar fashion under nitrogen atmosphere. The sample was heated up to 350° C. within 180 min where temperature was maintained for 4 h followed by natural cool down. The resultant catalyst powder was labeled Cat. 3b.

[0111] The materials exhibit the following characteristics which were determined by XRF (X-ray fluorescence) and TGZ analysis using a calibrated Hitachi H-7500 field transmission electron microscope operated at 100 keV, equipped with a CCD-Camera:

TABLE-US-00003 ID d.sub.p ω D 3a 4.0 nm 0.54 10 nm 3b 4.0 nm 0.6  9 nm

Examples 4 a,b

Preparation of Carbon Embedded Co—Cu—Mn-Nanoparticles

[0112] Carbon embedded Co-Cu-Mn-nanoparticles were prepared by dissolving 14.4 g citric acid (puriss,

[0113] Sigma Aldrich) in 75 mL of deionized water under constant stirring at room temperature. In a second beaker 14.9 g Cobalt(II)-acetate tetrahydrate ((CH.sub.3COO).sub.2Co*4 H.sub.2O, Sigma Aldrich), 2.9 g Cu(II)-acetate-Monohydrate ((CH.sub.3COO).sub.2Cu*H.sub.2O, Alfa Aesar) and 1.5 g Mn(II)-acetate tetrahydrate (Mn(CH.sub.3COO).sub.2*4 H.sub.2O, Sigma Aldrich) were dissolved in 75 mL of deionized water under constant stirring at room temperature. The Cobalt-Copper-Manganese-solution was slowly added to the citric acid solution and stirred for another 30 min at room temperature. The resultant solution was spray dried using a conventional mini spray dryer (Büchi, Mini Spray Dryer B-290) with constant inlet temperature of 220° C., outlet temperature of 125° C. and 25% pump speed. The obtained powder was split into two fractions with identical mass for the final thermo-treatment.

[0114] The first sample was thermo-treated in a muffle furnace under nitrogen atmosphere, with a 180 min ramp to 300° C., where temperature was maintained for another 4 h followed by natural cooling down. The resultant catalyst powder was labeled Cat. 4a.

[0115] The second sample was thermo-treated in a similar fashion under nitrogen atmosphere. The sample was heated up to 350° C. within 180 min where temperature was maintained for 4 h followed by natural cooling down. The resultant catalyst powder was labeled Cat. 4b.

[0116] The materials exhibit the following characteristics which were determined by XRF (X-ray fluorescence) and TGZ analysis using a calibrated Hitachi H-7500 field transmission electron microscope operated at 100 keV, equipped with a CCD-Camera:

TABLE-US-00004 ID d.sub.p ω D 4a 4.5 nm 0.51 11 nm 4b 5.0 nm 0.58 10 nm

Comparative Examples

[0117] For comparison to the state of the art, two “Cobalt on carbon support”-catalysts was prepared according to Westerhaus, Felix A., et al. “Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes” Nature Chemistry (2013).

[0118] A catalyst with 3 wt % Cobalt on a conventional Vulcan XC72R Carbon support was obtained according to Westerhaus et al. (Westerhaus, Felix A., et al. “Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes” Nature Chemistry (2013) page 538, table 1, entry 1) and labeled as Cat. 5.

[0119] A highly loaded catalyst with 20 wt % Cobalt on a conventional Vulcan XC72R Carbon support was obtained according to Westerhaus et al. (Westerhaus, Felix A., et al. “Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes” Nature Chemistry (2013) page 538, table 1, entry 1; with higher Co-loading) and labeled as Cat. 6.

[0120] Furthermore, a highly disperse Co/TiO.sub.2 was prepared according to Van Deelen, T. W., et al. “Preparation of Cobalt Nanocrystals Supported on Metal Oxides to Study Particle Growth in Fischer—Tropsch Catalysts.” ACS Catalysis (2018).

[0121] A catalyst with 7 wt % Cobalt on a conventional Evonik Aeroxide P25 TiO.sub.2-support was obtained according to Van Deelen et al. (Van Deelen, T. W., et al. “Preparation of Cobalt Nanocrystals Supported on Metal Oxides to Study Particle Growth in Fischer—Tropsch Catalysts.” ACS Catalysis (2018) page 10582, Incipient Wetness Impregnation) and labeled as Cat. 7.

[0122] The materials exhibit the following characteristics which were determined by XRF (X-ray fluorescence) and TGZ analysis using a calibrated Hitachi H-7500 field transmission electron microscope operated at 100 keV, equipped with a CCD-Camera:

TABLE-US-00005 ID d.sub.p ω D Cat. 5 30 nm 0.03 n.d.* Cat. 6 55 nm 0.20 n.d.* Cat. 7 45 nm 0.07 n.d.* *Catalyst materials Cat. 5, Cat. 6, and Cat. 7 exhibit a very inhomogeneous distribution of their metal content, with lager metal clusters in apparently random arrangement, instead of a finely dispersed nano-particle collocation as found in the materials obtained from examples 1 to 4. Determining D-values, therefore, does not appear meaningful.

Testing Catalytic Activity

[0123] Experiments to determine Catalytic activity and selectivity of the materials were performed in a batch-wise fashion using 200 mg of catalyst and 5 mmol of substrate in 5 ml of methanol.

[0124] Autoclaves were heated to the desired reaction temperature and agitated under a constant hydrogen pressure of 50 bar for all experiments. Reaction products were filtered and analyzed by means of GC-MS.

[0125] I. Hydrogenation of Methyl Crotonate to Methyl Butyrate

##STR00001##

TABLE-US-00006 Duration Temp. T reactant product ID Cat. ID h ° C. % %  1 Cat. 1 a 3.00 80.00 0.00 100.00  2 Cat. 1 b 2.00 80.00 0.00 100.00  3 Cat. 2 0.3 80.00 0.00 100.00  4 Cat. 4 a 2.00 80.00 0.00 100.00  5 Cat. 4 b 1.80 80.00 0.00 100.00  6 Cat. 4 a 35.00 25.00 0.00 100.00  7 Cat. 4 b 10.00 25.00 0.00 100.00  8 Cat. 3 a 8.00 80.00 0.00 100.00  9 Cat. 3 b 7.00 80.00 0.00 100.00 10 Cat. 5 20.00 80.00 67.10 32.90 11 Cat. 6 20.00 80.00 0.00 100.00 12 Cat. 7 20.00 80.00 0.00 100.00

[0126] II. Hydrogenation of Acetylnaphthalene

##STR00002##

TABLE-US-00007 Duration Temp. T reactant product side-product ID Cat. ID h ° C. % % % 13 Cat. 1 a 19.00 80.00 49.70 50.30 0.00 14 Cat. 1 b 19.00 80.00 0.00 100.00 0.00 15 Cat. 2 19.00 80.00 0.00 100.00 0.00 16 Cat. 4 a 0.40 80.00 0.00 96.20 3.8 17 Cat. 4 b 0.25 80.00 0.00 95.40 4.6 18 Cat. 3 a 8.00 80.00 0.00 76.5 23.5 19 Cat. 3 b 8.00 80.00 41.8 58.2 0.00 20 Cat. 5 20.00 80.00 98.1 0.00 1.8 21 Cat. 6 20.00 80.00 49.3 46.7 4.0 22 Cat. 7 20.00 80.00 97.1 0.00 2.9

[0127] III. Hydrogenation of N-Benzylidene-Benzylamine

##STR00003##

TABLE-US-00008 Duration Temp T reactant product side-product ID Cat. ID h ° C. % % % 23 Cat. 1 a 8.00 100.00 0.00 89.1 7.10 24 Cat. 1 b 10.00 100.00 0.00 90.3 4.40 25 Cat. 2 1.00 100.00 1.50 91.4 2.50 26 Cat. 4 a 6.00 100.00 0.00 99.2 0.6 27 Cat. 4 b 5.00 100.00 0.00 99.4 0.8 28 Cat. 4 a 48.00 25.00 0.00 100.00 29 Cat. 4 b 48.00 25.00 0.00 100.00 30 Cat. 3 a 8.00 100.00 0.00 98.5 1.5 31 Cat. 3 b 8.00 100.00 0.00 99.3 0.7 32 Cat. 5 12.50 100.00 3.00 95.3 1.70 33 Cat. 6 9.50 100.00 3.30 94.1 2.60 34 Cat. 7 9.50 100.00 97.40 0.00 2.60

[0128] IV. Hydrogenation of Dodecannitrile

##STR00004##

TABLE-US-00009 Duration Temp. T reactant product side-product ID Cat. ID h ° C. % % % 35 Cat. 1 a 18.00 80.00 81.0 17.50 1.30 36 Cat. 1 b 10.00 80.00 0.00 90.40 9.60 37 Cat. 2 10.00 80.00 0.00 89.40 10.60 38 Cat. 4 a 3.00 80.00 0.00 100.00 39 Cat. 4 b 4.00 80.00 0.00 75.8 24.2 40 Cat. 3 a 3.00 80.00 0.00 76.2 23.8 41 Cat. 3 b 4.00 80.00 53.1 40.4 6.4 42 Cat. 5 20.00 80.00 100.0 0.00 0.00 43 Cat. 6 20.00 80.00 29.1 60.7 10.4 44 Cat. 7 20.00 80.00 95.2 3.3 1.4

[0129] V. Amination of Cyclohexanone

##STR00005##

TABLE-US-00010 Duration Temp T reactant product side-product ID Cat. ID h ° C. % % % 45 Cat. 1 a 2.00 100.00 0.00 89.60 5.80 46 Cat. 1 b 3.00 100.00 0.00 93.40 6.60 47 Cat. 2 1.00 100.00 0.00 92.30 7.70 48 Cat. 4 a 2.00 100.00 0.00 64.6 35.4 49 Cat. 4 b 2.00 100.00 0.00 81.7 18.3 50 Cat. 3 a 2.00 100.00 0.00 90.0 10.0 51 Cat. 3 b 2.00 100.00 0.00 89.9 10.1 52 Cat. 5 24.0 100.00 24.4 9.2 66.5 53 Cat. 6 24.0 100.00 0.00 85.7 14.3 54 Cat. 7 24.0 100.00 0.00 72.1 27.9