Catalyst and method for its preparation

Abstract

A catalyst including gold, or a compound thereof, and sulphur, a compound of sulphur, trichloroisocyanuric acid or a metal dichloroisocyanurate on a support, together with a process for manufacturing the catalyst and its use in a chemical process are described.

Claims

1. A catalyst comprising gold, or a compound thereof, and trichloroisocyanuric acid or a metal dichloroisocyanurate on a support.

2. The catalyst according to claim 1, comprising from 0.01-10% of gold, by weight based on the weight of the total catalyst.

3. The catalyst according claim 1, wherein said support comprises carbon.

4. The catalyst according to claim 1, wherein said support comprises a metal oxide.

5. The catalyst according to claim 1, wherein said support is in the form of a powder, granulate or shaped unit.

6. The catalyst according to claim 1, wherein at least some of the gold is in a positive oxidation state.

7. The catalyst according to claim 1, further comprising a metal or a compound of a metal selected from the group consisting of cobalt, copper, lanthanum, cerium, lithium, sodium, potassium, rubidium, caesium, magnesium, calcium, strontium and barium.

8. A method of manufacturing the catalyst of claim 1, comprising the steps of: impregnating a catalyst support with a solution of gold or a compound thereof and a solution of at least one of trichloroisocyanuric acid or a metal dichloroisocyanurate; and drying the impregnated catalyst support.

9. A chemical process comprising reacting at least one chemical substrate in the presence of a catalyst comprising: a) gold, or a compound thereof; and b) trichloroisocyanuric acid or a metal dichloroisocyanurate, on a support.

10. The chemical process according to claim 9, comprising oxidation of said chemical substrate.

11. The process according to claim 9, wherein the chemical process is hydrochlorination of an alkyne comprising reacting said alkyne with hydrogen chloride in the presence of said catalyst.

12. The process according to claim 11, wherein the catalyst comprises from 0.01-10% by weight of gold.

13. The process according to claim 12, wherein the catalyst comprises from 0.01-0.6% by weight of gold.

14. The process according to claim 11, further comprising a step of treating said catalyst with hydrogen chloride in the absence of acetylene.

15. The process according to claim 11, wherein said support comprises carbon.

16. The process according to claim 11, wherein said support comprises a metal oxide.

17. The process according to claim 11, wherein said support is in the form of a powder, granulate or shaped unit.

18. The process according to claim 11, wherein at least some of the gold is in a positive oxidation state.

19. The process according to claim 11, wherein said catalyst further comprises a metal or a compound of a metal selected from the group consisting of cobalt, copper, lanthanum, cerium, lithium, sodium, potassium, rubidium, caesium, magnesium, calcium, strontium and barium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be further described in the following examples with reference to the attached drawings.

(2) FIG. 1: Plot of conversion vs time for catalysts of Examples 1 and 2

(3) FIG. 2: Plot of conversion vs time for catalyst of Examples 1 and 4

EXAMPLES

Example 1

Preparation of Catalyst According to the Invention

(4) A sufficient quantity of 3 mm steam activated carbon extrudates was crushed, and then sieved, to yield 52 g of particles with diameters between 0.7 mm and 1.4 mm. This material was soaked in a solution of HCl, made by dilution of 60 ml 36% HCl with 240 ml demineralised water, for 20 minutes and then washed twice with 300 ml demineralised water per wash. Thereafter the material was dried at 105 C.

(5) Ammonium thiosulphate (0.460 g) was dissolved in 42 ml water. A solution of HAuCl.sub.4 containing 0.143 g Au was added slowly to this solution with stirring to give a deep yellow-brown solution. 47.3 g of the sieved and acid-washed carbon was then impregnated with the gold thiosulphate solution described above using an incipient wetness technique. After standing for 30 minutes the material was dried overnight at 120 C. The resulting catalyst contained 0.34% Au, by weight. Analysis of the samples to determine the concentration of metals was carried out by ICP-OES (inductively coupled plasma-optical emission spectroscopy) following microwave digestion of the samples.

Example 2

(Comparative) Preparation of a Prior Art Catalyst

(6) An aqua-regia solution was prepared by mixing 5.8 ml HNO.sub.3 (69%) with 19.3 ml HCl (36%) and 3.9 ml of demineralised water. A solution of HAuCl.sub.4 containing 0.336 g Au was added to the aqua regia solution. 35 g of crushed and sieved carbon extrudates, (sieved to a particle size range of 0.7-1.4 mm) were impregnated with the gold-aqua regia solution using an incipient wetness technique. After standing for about 16 hours, the material was dried at 140 C. for 7 hours. The resulting catalyst contained 0.75% Au, by weight.

Example 3

Test for Activity Over Time in Hydrochlorination of Acetylene.

(7) 12.0 g of a catalyst as described in Example 1 (or Example 2) was loaded into a 7 mm diameter stainless steel tube, coiled so as to form a spiral shape, giving a bed length of 1 metre. Initially the sample was dried at 120 C. under a stream of dry nitrogen. The reactor was then heated to 180 C., and a flow of the mixed reactant gases was initiated (85 ml/min acetylene, 102 ml/min hydrogen chloride). Initially nearly 100% conversion was achieved, which slowly decreased to about 70% over the course of 24 days. The results (shown in FIG. 1) show that the activity of the 0.3% Au thiosulphate catalyst of Example 1 is comparable with the catalyst made in Example 2 from an aqua regia solution, having a much higher gold content (0.75%).

Example 4

Activity of Pre-Chlorinated Catalyst

(8) 12.0 g of a catalyst made as described in Example 1 was loaded into a 7 mm diameter stainless steel tube reactor, as described in Example 3. Initially the sample was dried at 120 C. under a stream of dry nitrogen. The reactor was then heated to 180 C., and a stream of hydrogen chloride (102 ml/min) was passed through the reactor for 4 hours to activate the catalyst. Acetylene was then introduced to give a mixed gas flow of 85 ml/min acetylene, 102 ml/min hydrogen chloride. The results (FIG. 2) show that the HCl pre-activation produces a significant increase in conversion compared with the non-activated sample during the course of the run.

Example 5

Preparation of Catalyst According to the Invention

(9) 5.8 g of 3 mm steam-activated carbon extrudates were soaked in 100 ml of 2M HCl for 30 minutes. The carbon was then washed with 250 ml portions of deionised water and dried at 120 C.

(10) Ammonium thiosulphate (0.186 g) was dissolved in 4.8 ml water. A solution of HAuCl.sub.4 containing 0.06 g of gold was added slowly to this solution with stirring to give a deep yellow-brown solution. The acid-washed carbon was then impregnated with this solution using the incipient wetness technique. The product was dried at overnight at 120 C. The resulting catalyst contained 1.0% Au, by weight.

(11) Analysis of the resulting catalyst particles by electron probe microanalysis (EPMA) showed that the particles had a gold layer around their periphery to a thickness of about 200 microns

Example 6

(Comparative) Preparation of Prior-Art Catalyst.

(12) 58 g of carbon extrudates were impregnated with an aqua-regia solution of gold chloride prepared by mixing 9.5 ml HNO.sub.3 (69%) with 32 ml HCl (36%) and 6.5 ml of demineralised water and a solution of HAuCl.sub.4 containing 0.58 g Au. After standing for about 16 hours, the material was dried at 140 C. for 7 hours. Inspection of the resulting catalyst particles by EPMA showed that the particles had a gold layer around their periphery to a thickness of about 200 microns.

Example 7

(Comparative) Preparation of Catalyst from Aqueous Gold Chloride

(13) A gold solution was prepared by mixing 0.14 g of HAuCl.sub.4 aqueous solution containing 41% Au with 4.8 ml of water. 6 g of 3 mm carbon extrudates were impregnated with this solution to incipient wetness. After standing the material was dried overnight at 105 C. The particles contained 1% gold, by weight. EPMA showed a gold layer having a thickness of 10 microns. This result indicates that the gold(III) ions are reduced to metallic gold when they contact the carbon of the support, which is a reducing material. The gold is therefore poorly dispersed and predominantly in a less active state than in the catalysts of the invention.

Example 8

Test for Activity at 24 Hours

(14) 1.5 g of catalyst was loaded into a 4 mm diameter glass reactor, giving a bed depth of 30 cm. Initially the sample was dried at 110 C. under a stream of dry nitrogen. The reactor was then maintained at 110 C., and a flow of the mixed reactant gases was initiated, diluted with nitrogen (50 ml/min acetylene, 60 ml/min hydrogen chloride, 120 ml/min nitrogen). These conditions are selected to give a maximum conversion for the catalysts of about 50% in order that different catalysts can be compared.

(15) The catalysts typically take up to 24 hours for the conversion behaviour to stabilise, thereafter following a more gradual and predictable decline. The conversion value after 24 hours, used as a measure of the relative activity of the catalyst, is shown in Table 1.

Examples 9-16

(16) Catalysts were prepared by impregnation of the carbon support with a solution of a gold compound/complexing agent, using the incipient wetness method as generally described in Examples 5-7. The amount of gold in the solution was calculated to provide a finished catalyst containing 1% of gold by weight. The gold compound, complexing agent and the solvent used are listed in Table 1. Example 9 was made without using any gold compound, i.e. as a blank for comparison. The catalysts were tested using the procedure described in Example 8 and the results, in the form of conversion % after 24 hours, are shown in Table 1.

(17) TABLE-US-00001 TABLE 1 % Conversion Catalyst Gold precursor compound solvent at 24 hours Example 5 HAuCl.sub.4 + (NH.sub.4).sub.2S.sub.2O.sub.3 water 23 Example 6 HAuCl.sub.4 + aqua regia aqua regia 22 (Comparative) Example 7 HAuCl.sub.4 water 5 (Comparative) Example 9 none aqua regia 3 (Comparative) Example 10 HAuCl.sub.4 + (Na).sub.2S.sub.2O.sub.3 water 27 Example 11 HAuCl.sub.4 + CaS.sub.2O.sub.3 water 23 Example 12 HAuCl.sub.4 + methanol 22 trichloroisocyanuric acid Example 13 HAuCl.sub.4 + sodium water 20 dichloroisocyanurate Example 14 HAuCl.sub.4 + potassium water 13 dichloroisocyanurate Example 15 sodium gold thiosulphate water 13 Example 16 HAuCl.sub.4 + thiomalic acid water 10

Example 17

Preparation of Catalyst According to the Invention

(18) 3 mm diameter carbon extrudates (2065 g) were soaked in hydrochloric acid, prepared by dilution of 0.75 I 36% HCl with 2.90 I demineralised water, for 1.5 hour and thereafter washed with demineralised water and dried at 110 C. overnight. A solution of HAuCl.sub.4 containing 11.00 g Au was diluted in 270 ml demineralised water. 35.66 g ammonium thiosulphate was dissolved in 1.0 I demineralised water. A gold thiosulphate solution was prepared by addition of the HAuCl.sub.4 solution to the ammonium thiosulphate solution with stirring. 1810 g of the same carbon extrudates were then impregnated with the gold thiosulphate solution using an incipient wetness technique. After standing the material was dried overnight at 125 C. The resulting catalyst contained 0.66% Au by weight.

Example 18

Preparation of Catalyst According to the Invention

(19) 3 mm diameter carbon extrudates (7100 g) were soaked in hydrochloric acid, prepared by dilution of 2.575 I 36% HCl with 10.000 I demineralised water, for 1 hour and thereafter washed with demineralised water and dried at 125 C. overnight.

(20) A solution of HAuCl.sub.4 containing 21.10 g Au was diluted in 1.35 I demineralised water. 68.46 g ammonium thiosulphate was dissolved in 3.5 I demineralised water. A gold thiosulphate solution was prepared by addition of the HAuCl.sub.4 solution to the ammonium thiosulphate solution with stirring and diluted to a final solution volume of 4875 ml. 6950 g of the carbon extrudates were then impregnated with the gold thiosulphate solution using an incipient wetness technique. After standing the material was dried overnight at 125 C. The resulting catalyst contained 0.37% Au by weight.

Example 19

(21) Catalysts according to the invention were tested using the procedure described in Example 8 and the results, in the form of conversion % after 24 hours, are shown in Table 2.

(22) TABLE-US-00002 TABLE 2 Catalyst % Au in catalyst % Conversion at 24 hours Example 5 1.00 23 Example 17 0.66 26 Example 18 0.37 15

Example 20

(23) A solution of HAuCl4 containing 2.71 g Au was diluted in 470 ml demineralised water and added to a solution of 8.78 g ammonium thiosulphate dissolved in 470 ml demineralised water. Thereafter the solution was diluted to a final volume of 950 ml. Carbon extrudates (3 mm diameter, acid washed, steam activated carbon) were used as received from commercial suppliers. 1888 g of the carbon extrudates were impregnated with the gold containing impregnation solution using an incipient wetness technique. After standing, the material was dried overnight at 120 C. ICP-OES analysis of the material produced indicated an Au assay of % Au=0.130% by weight.

(24) The catalyst was tested as described in Example 8 and the conversion after 24 hours was found to be 11.6%.

Example 21

Preparation and Testing of Catalyst Including Co

(25) A different sample of a catalyst was prepared substantially as described in Example 18, and tested according to the procedure described in Example 8. After 24 hours, a conversion of 19% was measured. 5.8 g of the same fresh catalyst was impregnated with 4.8 ml of an aqueous solution of the cobalt complex [Co(NH.sub.3).sub.4]Cl.sub.3, the concentration of Co being such as to give a 3:1 Co:Au molar ratio. After drying overnight at 125 C., the resulting Co-doped catalyst was tested as described in Example 8. After 24 hours, a conversion of about 33% was measured, showing a substantial enhancement over the original catalyst.

Example 22

(26) A solution of HAuCl.sub.4 containing 0.972 g Au was diluted in 100 ml demineralised water and added to a solution containing ammonium thiosulphate (3.0 g) in 100 ml demineralised water. The resultant solution was further diluted with demineralised water to a final volume of 375 ml. 4 mm diameter commercially supplied carbon extrudates (acid washed, steam activated carbon) were used as received. 635 g of the carbon extrudates were impregnated with the gold containing impregnation solution using an incipient wetness technique. After standing, the material was dried overnight at 105 C.

(27) ICP-OES analysis of the material produced indicated an Au assay of Au=0.130% by weight.

Example 23

Preparation of Catalyst Including Ca

(28) 0.174 g of Ca(OH).sub.2 was dissolved/slurried in 50 ml demineralised water and added to a solution of HAuCl.sub.4 containing 0.927 g Au in 50 ml demineralised water to form a solution of Ca(AuCl.sub.4).sub.2. Ammonium thiosulphate (3.0 g) was dissolved in 50 ml demineralised water and added to the solution of Ca(AuCl.sub.4).sub.2. The resultant impregnation solution was diluted to a final volume of 375 ml. 635 g of 4 mm diameter commercially supplied carbon extrudates (acid washed, steam activated carbon) were impregnated with the gold containing impregnation solution using an incipient wetness technique. After standing, the material was dried overnight at 105 C. ICP-OES analysis of the dried material indicated assays of Au=0.125%, Ca=0.04% by weight.

Example 24

Alternative Preparation of Catalyst Including Ca

(29) A solution of HAuCl.sub.4 containing 0.927 g Au in 100 ml demineralised water was added to a solution containing ammonium thiosulphate (3.0 g) and CaCl.sub.2 (0.5 g) in 100 ml demineralised water. The resultant solution was further diluted with demineralised water to a final volume of 375 ml. 635 g of the 4 mm diameter carbon extrudates (acid washed, steam activated carbon) were impregnated with the gold-containing impregnation solution using an incipient wetness technique. After standing, the material was dried overnight at 105 C. ICP-OES analysis of the material produced indicated assays of Au=0.130%, Ca=0.05% by weight.

Example 25

Catalyst Testing

(30) Catalysts prepared as described in Examples 22-24 were tested using the following method. 4.36 g of catalyst, in the form of 4 mm extrudates, was loaded into a 40 mm diameter glass reactor, giving a bed depth of 20 cm. Initially the sample was dried at 120 C. under a stream of dry nitrogen. The reactor was then maintained at 120 C., the nitrogen flow stopped, and a flow of the mixed reactant gases was initiated (28.5 ml/min acetylene, 34.2 ml/min hydrogen chloride). The flow of the reactant gases was then increased in steps over a 45 minute period, reaching the maximum flow of 114 ml/min acetylene, 125 ml/min hydrogen chloride, which was maintained over the duration of the experiment. Whilst the external temperature was maintained at 120 C., the internal bed temperature was monitored to ensure that the temperature did not exceed 180 C. as the gas flow was increased. These conditions are selected so as to minimise thermal deactivation caused by the exothermic reaction of acetylene with hydrogen chloride.

(31) The catalysts typically take up to 24 hours for the conversion behaviour to stabilise, thereafter following a more gradual and predictable decline. The conversion value after 24 hours, used as a measure of the relative activity of the catalyst, is shown in Table 3.

(32) TABLE-US-00003 TABLE 3 Other metal present % Conversion Catalyst % Au in catalyst (% by weight) at 24 hours Example 22 0.130 none 55 Example 23 0.125 Ca (0.04) 49 Example 24 0.130 Ca (0.05) 49