PROCESS FOR THE PREPARATION OF TRANSITION METAL NANOPARTICLES

Abstract

A process for the preparation of transition metal nanoparticles, the process comprising: (a) providing a mixture comprising one or more salts of one or more transition metals M, one or more complexing agents C, and a solvent system S; (b) optionally adjusting the pH of the mixture provided in (a) to a pH comprised in the range of from 4 to 8; (c) heating the mixture provided in (a) or obtained in (b) for obtaining a colloidal suspension of transition metal nanoparticles; (d) optionally isolating the transition metal nanoparticles obtained in (c), preferably by centrifugation and/or evaporation to dryness of the colloidal suspension obtained in (c) wherein the mixture provided in (a) and heated in (c) or obtained in (b) and heated in (c) does not comprise polyvinyl sulfate and/or polyvinylpyrrolidone.

Claims

1. A process for the preparation of transition metal nanoparticles, the process comprising: (a) providing a mixture comprising one or more salts of one or more transition metals M, one or more complexing agents C, and a solvent system S; (b) optionally adjusting the pH of the mixture provided in (a) to a pH comprised in the range of from 4 to 8; (c) heating the mixture provided in (a) or obtained in (b) for obtaining a colloidal suspension of transition metal nanoparticles; and (d) optionally isolating the transition metal nanoparticles obtained in (c), preferably by centrifugation and/or evaporation to dryness of the colloidal suspension obtained in (c); wherein the mixture provided in (a) and heated in (c) or obtained in (b) and heated in (c) does not comprise polyvinyl sulfate and/or polyvinylpyrrolidone.

2. The process of claim 1, wherein the mixture provided in (a) and heated in (c) or obtained in (b) and heated in (c) does not comprise a polyvinyl sulfate, polyvinylpyrrolidone, a copolymer comprising vinylpyrrolidone, and/or a fatty acid-substituted or unsubstituted polyoxyethylene.

3. The process of claim 1, wherein the mixture provided in (a) and heated in (c) or obtained in (b) and heated in (c) does not comprise ascorbic acid, an ascorbate, formic acid, a formate, and/or a borohydride.

4. The process of claim 1, wherein the mixture provided in (a) and heated in (c) or obtained in (b) and heated in (c) consists of the one or more salts of one or more transition metals M, the one or more complexing agents C, the solvent system, and optionally one or more compounds employed for adjusting the pH of the mixture in (b).

5. The process of claim 1, wherein the one or more complexing agents C are selected from the group consisting of carboxylates and salts thereof.

6. The process of claim 1, wherein the mixture provided in (a) and heated in (c) or obtained in (b) and heated in (c) does not comprise a complexing agent other than the one or more complexing agents C.

7. The process of claim 1, wherein in (b) the pH of the mixture provided in (a) is adjusted to a pH comprised in the range of from 5 to 7.

8. The process of claim 1, wherein in (a) the one or more transition metals M are selected from the group consisting of Cu, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, and Au, including mixtures of two or more thereof.

9. The process of claim 1, wherein in the mixture provided in (a), the C : M molar ratio of the one or more complexing agents C to the one or more transition metals M is comprised in the range of from 1 to 200.

10. The process of claim 1, wherein in the mixture provided in (a), the S : M molar ratio of the solvent system S to the one or more transition metals M is comprised in the range of from 50 to 3500.

11. The process of claim 1, wherein the process further comprises: (e) contacting the colloidal suspension of transition metal nanoparticles obtained in (c) or the transition metal nanoparticles obtained in (d) with a support material for supporting the transition metal nanoparticles on the support material.

12. A colloidal suspension of transition metal nanoparticles obtainable and/or obtained according to the process of claim 1.

13. Transition metal nanoparticles obtainable and/or obtained according to the process of claim 1 comprising (d).

14. A catalyst comprising transition metal nanoparticles obtainable and/or obtained according to the process of claim 11.

15. (canceled)

Description

BRIEF DESCRIPTION OF FIGURES

[0164] FIG. 1: shows a TEM image of a sample colloidal suspension prepared according to Example 1.

[0165] FIG. 2: shows a particle size distribution of a sample colloidal suspension prepared according to Example 1. On the abscissa, the particle size is given in nm and on the ordinate the frequency is given in %.

[0166] FIG. 3: shows the yield of saturated aldehyde for a common catalyst. On the abscissa, the reaction time in hours is given, and on the ordinate, the yield in % is given. The line starting at about 1 hour with a yield of 40% relates to the first cycle, and the other four lines relate to the following four recycles.

[0167] FIG. 4: shows the yield of saturated aldehyde for a heterogeneous catalyst according to Example 3 of the present invention. On the abscissa, the time in hours is given, and on the ordinate, the yield in % is given. The upper line relates to the first cycle, and the other four lines relate to the following four recycles.

[0168] FIG. 5: shows the selectivity towards alcohol for a common catalyst. On the abscissa, the reaction time in hours is given, and on the ordinate, the selectivity towards alcohol in % is given.

[0169] FIG. 6: shows the selectivity towards alcohol for a heterogeneous catalyst according to Example 3 of the present invention. On the abscissa, the reaction time in hours is given, and on the ordinate, the selectivity towards alcohol in % is given.

[0170] FIG. 7: shows the selectivity towards fully saturated aldehyde for a common catalyst. On the abscissa, the reaction time in hours is given, and on the ordinate, the selectivity towards fully saturated aldehyde in % is given.

[0171] FIG. 8: shows the selectivity towards fully saturated aldehyde for a heterogeneous catalyst according to Example 3 of the present invention. On the abscissa, the reaction time in hours is given, and on the ordinate, the selectivity towards fully saturated aldehyde in % is given. The upper line shows the first cycle.

CITED LITERATURE

[0172] M. Michaelis et al. in J. Phys. Chem. 1994, 98, pp. 6212-6215 [0173] M. Shao et al. in Chem. Commun. 2011, 47, pp. 6566-6568 [0174] Z.-L. Wang et al. in Scientific Reports 2 : 598, pp. 1-6 [0175] H. Lv et al. in Nano Energy 2016, 29, 149-165 [0176] US 10,493,433 B2