METAL POWDEROUS CATALYST FOR HYDROGENATION PROCESSES

Abstract

The present invention relates to a metal powder catalyst and its use in the selective catalytic hydrogenation of organic starting materials comprising a carbon-carbon triple bond. The powder catalyst comprises a metal alloy carrier, wherein the metal alloy comprises (i) 55 weight-% (wt-%)-80 wt-%, based on the total weight of the metal alloy, of Co, and (ii) 20 wt-%-40 wt-%, based on the total weight of the metal alloy, of Cr, and (iii) 2 wt-%-10 wt-%, based on the total weight of the metal alloy, of Mo, and wherein the said metal alloy is coated by a metal oxide layer and impregnated with Pd, and is characterized in that the metal oxide layer comprises CeO.sub.2.

Claims

1. Use of a powderous catalytic system which comprises a metal alloy carrier, wherein the metal alloy comprises (i) 55 weight-% (wt-%)-80 wt-%, based on the total weight of the metal alloy, of Co, and (ii) 20 wt-%-40 wt-%, based on the total weight of the metal alloy, of Cr, and (iii) 2 wt-%-10 wt-%, based on the total weight of the metal alloy, of Mo, and wherein the said metal alloy is coated by a metal oxide layer and impregnated with Pd, characterized in that the metal oxide layer comprises CeO.sub.2, in selective catalytic hydrogenation with hydrogen of organic starting material comprising a carbon-carbon triple bond (preferably alkynol compounds).

2. Use according to claim 1, wherein the organic starting material comprising a carbon-carbon triple bond is a compound of formula (I) ##STR00005## wherein R.sub.1 is linear or branched C.sub.1-C.sub.35 alkyl or linear or branched C.sub.5-C.sub.35 alkenyl moi-ety, wherein the C chain can be substituted, and R.sub.2 is linear or branched C.sub.1-C.sub.4 alkyl, wherein the C chain can be substituted, and R.sub.3 is H or C(CO)C.sub.1-C.sub.4alkyl.

3. Use according to claim 1, wherein the organic starting material comprising a carbon-carbon triple bond is any compound of the following formulae ##STR00006##

4. Use according to claim 1, wherein hydrogen is used in the form of H.sub.2 gas.

5. Use according to claim 1, wherein the metal alloy carrier comprises (i) 55 wt-%-70 wt-%, based on the total weight of the metal alloy, of Co, and (ii) 20 wt-%-35 wt-%, based on the total weight of the metal alloy, of Cr, and (iii) 4 wt-%-10 wt-%, based on the total weight of the metal alloy, of Mo.

6. Use according to claim 1, wherein the metal alloy comprises at least one further metal chosen from the group consisting of Cu, Fe, Ni, Mn, Si, Ti, Al and Nb.

7. Use according to claim 1, wherein the metal alloy comprises carbon.

8. Use according to claim 1, wherein the metal alloy is coated with a layer of CeO.sub.2 and optionally at least one further metal (Cr, Mn, Mg, Cu and/or Al) oxide.

9. Powderous catalytic system which comprises a metal alloy carrier, wherein the metal alloy comprises (i) 55 weight-% (wt-%)-80 wt-%, based on the total weight of the metal alloy, of Co, and (ii) 20 wt-%-40 wt-%, based on the total weight of the metal alloy, of Cr, and (iii) 2 wt-%-10 wt-%, based on the total weight of the metal alloy, of Mo, and wherein the said metal alloy is coated by a metal oxide layer and impregnated with Pd, characterized in that the metal oxide layer comprises CeO.sub.2.

Description

EXAMPLES

Example 1: Preparation of Metal Powder Catalyst

[0114] The EOS CobaltChrome MP1 was heated at 450 C. for 3 h in air. For preparation of the primer solution, Ce(NO.sub.3).sub.3.6H.sub.2O (508 mmol) and 700 mL water were added to a beaker. The mixture was stirred until the salt was completely dissolved. The solution was heated to 90 C. and ZnO (508 mmol) was slowly added to the solution. The stirring was maintained at 90 C. and 65% nitric acid was added dropwise until all ZnO was completely dissolved (final c.sub.HNO3=1 M). Afterwards the solution was cooled to room temperature and filtrated through a 0.45 m membrane filter. The deposition of ZnO/CeO.sub.2 was performed by adding thermally treated MP1 powder (10.0 g) to 25 mL of the precursor solution. This mixture was stirred at room temperature for 15 min. Afterwards the suspension was filtered via a 0.45 m membrane filter and dried under vacuum at 40 C. for 2 h followed by calcination at 450 C. for 1 h. This process was repeated until the desired number of primer layers had been deposited.

[0115] Sodium tetrachloropalladate(II) (0.48 mmol) was dissolved in 133 mL of Millipore water and PEG-MS40 (3.2 mmol) was added. The solution was heated to 60 C. and sonication was started at this temperature. A fresh prepared solution of sodium formate (16 mM, 67 mL) were added. The solution was sonicated for further 60 minutes at this temperature and then cooled to room temperature followed by addition of the coated MP1 (10.0 g). The suspension was stirred at room temperature for 60 minutes followed by filtration via a 0.45 m membrane filter. The residue was washed with water and dried under vacuum at 40 C. for 2 h. The catalyst was subjected to a temperature treatment at 300 C. for 4 h (temperature ramp10/min) under H.sub.2-Ar flow (1:9; total flow rate450 ml/min).

[0116] Hydrogenation Examples

[0117] Selective Semi-Hydrogenation of an Alkyne to an Alkene

[0118] 40.0 g of 2-methyl-3-butyne-2-ol (MBY) and the desired amount of metal powder catalyst were added to a 125 mL autoclave reactor. Isothermal conditions during the hydrogenation reaction (338 K) were maintained by a heating/cooling jacket. The reactor was equipped with a gas-entrainment stirrer. Pure hydrogen was supplied at the required value under nitrogen atmosphere. After purging with nitrogen, the reactor was purged with hydrogen and heated to the desired temperature. The pressure in the reactor (3.0 bar) was maintained during the experiments by supplying hydrogen from external reservoir. The reaction mixture was stirred with 1000 rpm. Liquid samples (200 L) were periodically withdrawn from the reactor starting at a minimum conversion of 95% of MBY and analysed by gas-chromatography (HP 6890 series, GC-system). Selectivity is reported as amount of the desired semi-hydrogenation product (2-methyl-3-butene-2-ol (MBE)) compared to all reaction products.

[0119] Tables 1a and 1b: Test Results of Different Oxide Layers, Pd-Source, Pd-Amount and Pd-Reduction

[0120] The catalysts prepared according to the process described in the example above and they were thermal activated as mentioned in the preparation procedure Reaction conditions for a: 500 mg catalyst, 40.0 MBY, 1000 rpm, 3.0 bar H.sub.2, 65 C. Reaction conditions for b: 158 mg catalyst, 30.0 MBY, 1000 rpm, 3.0 bar H.sub.2, 65 C.

[0121] Exp. 1 is a comparison example using an oxide layer known from the prior art.

TABLE-US-00001 TABLE 1a Oxide Layer & Pd-source Exp Layer # (loading wt %) Pd-reduction procedure 1a Al.sub.2O.sub.3/ZnO (3) PdCl.sub.2 (0.50) H.sub.2 bubbling (25 C.) 2b CeO.sub.2/ZnO (3) Na.sub.2PdCl.sub.4 (0.50) H.sub.2 bubbling (25 C.) 3b CeO.sub.2/ZnO (3) Na.sub.2PdCl.sub.4 (0.5) HCOONa, PEG, sonication (60 C.)

TABLE-US-00002 TABLE 1b Conv. Time Select. Activity Exp (%) (min) (%) (mmol/sg.sub.Pd) 1a 99.8 740 95.3 122.8 2b 99.9 122 95.6 317.1 3b 99.7 122 96.9 335.0

[0122] It can be seen that the new metal oxide powders show an improved activity as well as an improved selectivity.

.sup.a Conditions: 500 mg catalyst, 40.0 MBY, 1000 rpm, 3.0 bar H.sub.2, 65 C.
.sup.b Conditions: 158 mg catalyst, 30.0 MBY, 1000 rpm, 3.0 bar H.sub.2, 65 C.

[0123] The catalyst according to the present invention show improved properties when used in selective hydrogenation processes.