GOLD CONTAINING CATALYST, METHOD OF PREPARATION AND USE

Abstract

The present invention relates to improvements in known gold containing catalysts. In particular, the present invention relates to improving the stability and/or inhibition of deactivation of gold containing catalysts via the addition of an inorganic oxide, hydroxide, oxo-salt or oxo-acid. There is also disclosed a method for preparing said catalyst most suitably via an impregnation method. Such catalysts are useful in the production of vinyl chloride monomer.

Claims

1-15. (canceled)

16. A catalyst comprising: a complex of gold with a sulphur-containing ligand; and an additive selected from the group consisting of: an inorganic oxide, hydroxide, oxo-salt or oxo-acid; on a support.

17. The catalyst according to claim 16, wherein the additive is: (i) an oxide or hydroxide of a metallic, metalloid or non-metal element; or (ii) an oxo-salt or oxo-acid of a metalloid or non-metallic element.

18. The catalyst according to claim 16, wherein the additive is an oxide, hydroxide, oxo-salt or oxo-acid of an element selected from the group consisting of: boron, silicon, sulfur or phosphorus.

19. The catalyst according to claim 16, wherein the additive is an oxide, hydroxide, oxo-salt or oxo-acid of boron, silicon or phosphorus and the catalyst has a boron, silicon, sulfur or phosphorus content of 0.01-10 wt %.

20. The catalyst according to claim 16, comprising between 10 and 0.1% of said additive, by weight based on the total weight of the catalyst.

21. The catalyst according to claim 16, wherein the additive is selected from the group consisting of: a boric acid, a silicic acid, phosphoric acid or sulphuric acid.

22. The catalyst according to claim 16, wherein the additive is selected from the group consisting of: sodium metasilicate pentahydrate, sodium tetraborate, boric acid, and trisodium orthophosphate.

23. The catalyst according to claim 16, comprising no more than 0.1% of gold, by weight based on the total weight of the total catalyst.

24. The catalyst according to claim 16, comprising no more than 0.05% of gold, by weight based on the total weight of the catalyst.

25. The catalyst according to claim 16, wherein said support comprises carbon.

26. The catalyst according to claim 16, wherein said sulphur-containing ligand is selected from the group consisting of a sulphate, a sulphonate, a thiosulphate, a thiocyanate, a thiourea, a thiol or thionyl chloride.

27. A method of manufacturing a catalyst according to claim 16, wherein, i) a solution of gold is provided, ii) a solution of sulphur containing ligand is provided, iii) a solution of an additive or precursor thereof is provided, iv) the gold solution is mixed with the sulphur containing ligand solution to provide a gold complex impregnation solution, and v-i) a catalyst support is impregnated with the gold complex impregnation solution, followed by drying the impregnated support, then impregnated with the solution from (iii), followed by drying the impregnated support, or v-ii) a catalyst support is impregnated with the solution from step (iii), followed by drying then impregnated support, then impregnated with the gold complex impregnation solution, followed by drying the impregnated support.

28. A method of manufacturing a catalyst according to claim 16, wherein, i) an impregnation solution is provided comprising a gold complex and an additive or a precursor thereof; ii) a catalyst support is impregnated with the solution from step (i) to produce an impregnated support, followed by drying the impregnated support.

29. The method according to claim 27, wherein the additive precursor is transformed into an inorganic oxide, hydroxide, oxo-salt or oxo-acid via a thermal or chemical degradation.

30. The method according to claim 28, wherein the additive precursor is transformed into an inorganic oxide, hydroxide, oxo-salt or oxo-acid via a thermal or chemical degradation.

31. A process for the hydrochlorination of an alkyne comprising reacting said alkyne with hydrogen chloride in the presence of a catalyst according to claim 16.

Description

[0081] The invention will now be further described in the following examples with reference to the attached drawings, in which:—

[0082] FIG. 1 is an SEM image of a fresh untreated 0.1% gold containing catalyst surface.

[0083] FIG. 2 is an SEM image of a fresh 1% boric acid treated 0.1% gold containing catalyst surface.

[0084] FIG. 3 is an SEM image of nanotube formation on the used untreated 0.1% gold containing catalyst surface.

[0085] FIG. 4 is an SEM image of the used 1% boric acid treated 0.1% gold containing catalyst devoid of nanocarbon tube formation.

[0086] FIG. 5 illustrates the relative conversion rates to VCM obtained for untreated 0.1 and 0.05% gold containing catalysts versus a 0.05% gold containing catalyst treated with the addition of sodium silicate.

[0087] FIG. 6 illustrates a significant increase in VCM conversion obtained by a 0.05% gold containing catalyst with the addition of a silicate salt versus a gold containing catalyst in the absence of such a silicate salt.

EXAMPLES

Example 1 (Comparative). Preparation of a 0.1% Au Thiosulphate Catalyst According to the Prior Art

[0088] 0.142 g of an HAuCl.sub.4 solution containing 41% Au was diluted in 24 ml of water. Separately, 0.186 g of anhydrous sodium thiosulphate was dissolved in 24 ml of water. The gold-containing solution was then added to the thiosulphate solution with stirring, to give a pale yellow mixed solution of prepared gold complex. 4.8 ml of this gold complex solution was then added to 5.8 g of commercially available activated carbon pellets, with stirring. The carbon absorbed all the liquid within about 5 minutes. After leaving the product to air-dry for about one hour, the material was then dried at 120° C. overnight, to give a catalyst containing approximately 0.1% Au. FIG. 1 is an SEM image of this freshly prepared untreated catalyst.

Example 2. Test for Carbon Nanotube Formation

[0089] 5 g of the catalyst prepared as in example 1, was loaded into a 2 cm diameter stainless steel tube, and the bed formed supported at either end with silica wool packing. The tube was then placed in a tube furnace. A mixture of HCl and C.sub.2H.sub.2 (molar ratio 1.2:1) was passed over the catalyst at a flow rate of 240 ml/min, at a temperature of 220° C. Initial conversion to VCM was about 90%, falling to 65% after 48 hours. After 48 hours, the catalyst was flushed with nitrogen, cooled, and then removed from the furnace. Optical examination showed the presence of carbon nanotubes on the carbon pellets. The degree of nanotube formation was assessed as follows: 0=no nanotubes present; 1=nanotubes present on some particles; 2=nanotubes present on many particles; 3=nanotubes present on most particles.

[0090] SEM examination showed the coating to consist of a mass of carbon nanotubes, each nucleated by a gold particle as shown in FIG. 3. The degree of nanotube formation for this example was 3.

Example 3. Preparation of a Catalyst According to the Present Invention

[0091] The catalyst was prepared as in example 1, except that 0.58 g of an additive in the form of sodium metasilicate pentahydrate was dissolved in the HAuCl.sub.4 solution. Thereafter the procedure was the same as for example 1.

Example 4. Preparation of a Catalyst According to the Present Invention

[0092] The catalyst was prepared as in example 1, except that 0.58 g of an additive in the form of sodium tetraborate was dissolved in the HAuCl.sub.4 solution. Thereafter the procedure was the same as for example 1.

Example 5. Preparation of a Catalyst According to the Present Invention

[0093] The catalyst was prepared as in example 1, except that 0.58 g of boric acid was dissolved in the HAuCl.sub.4 solution. Thereafter the procedure was the same as for example 1. FIG. 2 is an SEM image of this fresh boric acid treated catalyst.

Example 6. Preparation of a Catalyst According to the Invention

[0094] The catalyst was prepared as in example 1, except that 0.58 g of trisodium orthophosphate was dissolved in the HAuCl.sub.4 solution. Thereafter the procedure was the same as for example 1.

Example 7. Testing of Catalysts According to the Invention for Nanotube Formation

[0095] Catalysts prepared as in examples 3-6 were tested for nanotube formation, according to the method given in Example 2, for time periods ranging from two to five days. In all cases carbon nanotube formation was either completely prevented (degree of nanotube formation=0) or present only on a few microscopic areas of the pellets (degree of nanotube formation=1). FIG. 4 is an SEM image of the boric acid treated catalyst of Example 5, after testing in accordance with the method of Example 2; here it can be seen that there is an increase in gold particle size, but no discernible nanotube growth. The degree of nanotube formation for this example was 0.

Example 8 (Comparative). Preparation of a 0.05% Au Catalyst According to the Prior Art

[0096] The catalyst was prepared as in example 1, except that 0.071 g of an HAuCl.sub.4 solution containing 41% Au was used to prepare the diluted HAuCl.sub.4 solution; and 0.093 g of sodium thiosulphate was used to prepare the thiosulphate solution. The resulting catalyst contained approximately 0.05% Au.

Example 9. Preparation of an 0.05% Au Catalyst According to the Present Invention

[0097] The catalyst was prepared as in example 8, except that 0.58 g of sodium metasilicate pentahydrate was dissolved in the HAuCl.sub.4 solution. Thereafter the procedure was the same as for example 8.

Example 10. Testing of 0.05% Au Catalyst According to the Present Invention for Increased Activity

[0098] The 0.05% Au catalyst with the silicate additive, according to Example 9, was subjected to the conversion test described in example 2. The rates of conversion are shown in FIG. 6, where it can be seen that a significant increase in conversion to VCM was obtained by the catalyst containing the silicate, versus the catalyst in which no silicate is present. For the material prepared in Example 9, nanotube formation was absent after six days, as can be seen in FIG. 5.

[0099] FIG. 5 shows the rate of conversion to VCM at 220° C. as per Example 2, but over a longer time period (up to 6 days, opposed to 48 hours) for two untreated catalysts, one containing 0.1% Au, and the other 0.05% Au, as compared to the 0.05% Au when treated with sodium silicate addition, as described above. In FIG. 5 it can be clearly seen that the addition of the sodium silicate allows the lower 0.05% Au containing catalyst to achieve a selectivity comparable to the higher 0.1% Au containing (but untreated) catalyst.

[0100] The improvement in conversion demonstrated in Example 10 for a 0.05% Au and silicate containing catalyst does not apparently occur for an 0.1% Au catalyst, although nanotube formation is advantageously inhibited. Therefore, the present invention is particularly suited and desirable in catalysts which have less than 0.1% gold.

Examples 11-17

[0101] A solution of HAuCl.sub.4 containing 0.100 g Au was diluted with the amount of demineralised water (DI) indicated. Separately, solutions of the sulfur-containing ligand and the additive were prepared with the amount of demineralised water (DI) indicated. The solutions were combined in the order indicated to produce a gold containing impregnation solution. This solution was then added to 100 g (dry weight) commercially available activated carbon pellets, via the incipient wetness technique, with mixing. The impregnated material was left to stand for approximately 30 minutes, during which all the added solution was adsorbed. The material was then dried at 105° C. overnight to give a catalyst containing approximately 0.1% Au.

[0102] In the case of Example 17, pH adjustment was carried out as follows. A solution of HAuCl.sub.4 containing 0.100 g Au was diluted with 30 ml of demineralised water. A ca. 5% KOH solution was prepared by dissolving 5 g NaOH in 100 ml demineralised water. Approximately 1 ml of the KOH solution was added dropwise to the gold containing solution to form a solution having a pH of ca. 6.8. Separately 0.336 g ammonium thiosulphate was dissolved in 30 ml demineralised water. The gold-containing solution was then added to the ammonium thiosulphate solution with stirring, to give a mixed solution of prepared gold complex. The resulting solution was then used in the incipient wetness technique according to the above procedure.

[0103] XPS analysis of examples 11-16 indicated the presence of SiO.sub.2 in the material formed following drying at 105° C. overnight.

[0104] The catalysts were tested for carbon nanotube formation according to the procedure in Example 2.

TABLE-US-00001 TABLE 1 Degree of HAuCl4 solution Ligand solution Additive solution Order of addition to form nanotube Example [HAuCl.sub.4] [Ligand] [Additive] impregnation solution pH adjustment formation 11 0.100 g HAuCl.sub.4 0.373 g sodium 1.162 g sodium [HAuCl.sub.4] to [Ligand] then −None  0 in 12 mL DI thiosulphate metasilicate pentahydrate add [Additive] in 24 mL DI in 24 mL DI 12 0.100 g HAuCl.sub.4 0.372 g sodium 1.161 g sodium [HAuCl.sub.4] to [Additive] −None  0 in 12 mL DI thiosulphate metasilicate pentahydrate then add [Ligand] in 24 mL DI in 24 mL DI 13 0.100 g HAuCl.sub.4 — 1.160 g sodium [HAuCl.sub.4] to [Additive] None 3 (Comparative) in 30 mL DI metasilicate pentahydrate in 30 mL DI 14 0.100 g HAuCl.sub.4 0.200 g sodium 1.162 g sodium [HAuCl.sub.4] to [Ligand] then None — in 12 mL DI thiocyanate metasilicate pentahydrate add [Additive] in 24 mL DI in 24 mL DI 15 0.100 g HAuCl.sub.4 0.200 g sodium 1.162 g sodium [HAuCl.sub.4] to [Additive] None 3 in 12 mL DI thiocyanate metasilicate pentahydrate then add [Ligand] in 24 mL DI in 24 mL DI 16 0.100 g HAuCl.sub.4 0.180 g thiourea 0.350 g silicic acid [HAuCl.sub.4] to [Ligand] then None 1 in 12 mL DI in 24 mL DI in 24 mL DI add [Additive] 17 0.100 g HAuCl.sub.4 0.336 g ammonium — [HAuCl.sub.4] to [Ligand] [HAuCl.sub.4] adjusted to pH — (Comparative) in 30 mL DI thiosulphate 6.8 using 1M KOH in 30 mL DI

[0105] Zr, Ce and La Precursors

Example 18 (Comparative)

[0106] A solution of HAuCl.sub.4 containing 0.100 g Au was diluted with 12 ml of demineralised water. A ca. 1M NaOH solution was prepared by dissolving 4 g NaOH in 100 ml demineralised water. 1.60 g of the prepared 1M NaOH solution was added dropwise to the gold containing solution to form solution having a pH of ca. 6.5. Separately 0.336 g sodium thiosulphate was dissolved in 12 ml demineralised water. The gold-containing solution was then added to the sodium thiosulphate solution with stirring, to give a mixed solution of prepared gold complex, having a pH of ca. 11.2. A further 12 ml of the previously prepared 1M NaOH solution and 22 ml demineralised water were added to the gold containing solution to give a solution of the prepared gold complex, having a pH of ca. 12.3. The resultant gold containing solution was then added to 100 g (dry weight) commercially available activated carbon pellets, via the incipient wetness technique, with mixing. The impregnated material was left to stand for approximately 30 minutes, during which all the added solution was adsorbed. The material was then dried at 105° C. overnight to give an Au/C catalyst containing approximately 0.1% Au. This catalyst was tested as in Example 2. The degree of carbon nanotube formation was 1.

Example 19

[0107] 0.1% Au/C catalyst was prepared was prepared as in example 18. Separately, 1.467 g zirconyl oxynitrate dihydrate [ZrO(NO.sub.3).sub.2.2H.sub.2O] was dissolved in 30 ml demineralised water and this solution was added to 50 g of the dried gold containing carbon pellets via the incipient wetness impregnation technique. After leaving the material to stand for approximately 30 minutes, the material was dried at 105° C. overnight, to give a catalyst containing ca. 0.1% Au and 1% Zr.

Example 20

[0108] 0.1% Au/C catalyst was prepared was prepared as in example 18. Separately 1.550 g cerium nitrate hexahydrate [Ce(NO.sub.3).sub.3.6H.sub.2O] was dissolved in 30 ml demineralised water and this solution was added to 50 g of the dried gold containing carbon pellets via the incipient wetness impregnation technique. After leaving the material to stand for approximately 30 minutes, the material was dried at 105° C. overnight, to give a catalyst containing ca. 0.1% Au and 1% Ce. This catalyst was tested as in Example 2. The degree of carbon nanotube formation was 1.

Example 21

[0109] 0.1% Au/C catalyst was prepared was prepared as in example 18. Separately 1.335 g lanthanum chloride heptahydrate [LaCl.sub.3.7H.sub.2O] was dissolved in 30 ml demineralised water and this solution was added to 50 g of the dried gold containing carbon pellets via the incipient wetness impregnation technique. After leaving the material to stand for approximately 30 minutes, the material was dried at 105° C. overnight, to give a catalyst containing ca. 0.1% Au and 1% La.

[0110] It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.

[0111] The invention also includes the following embodiments: [0112] 1. A catalyst comprising a complex of gold with a sulphur-containing ligand and inorganic salt or acid on a support. [0113] 2. A catalyst according to embodiment 1, comprising between 10 and 0.1% inorganic salt or acid, by weight based on the total weight of the catalyst. [0114] 3. A catalyst according to embodiment 1, comprising between 5 and 0.1% inorganic salt or acid, by weight based on the total weight of the catalyst. [0115] 4. A catalyst according to embodiment 1, comprising between 3 and 0.5% inorganic salt or acid, by weight based on the total weight of the catalyst. [0116] 5. A catalyst according to any preceding embodiment, wherein the inorganic acid or salt is an inorganic acid selected from a boric acid, phosphoric acid or sulphuric acid. [0117] 6. A catalyst according to any one of embodiments 1 to 4, wherein the inorganic acid or salt is an inorganic salt selected from an ammonium, silicate, borate or phosphate salt. [0118] 7. A catalyst according to embodiment 6, wherein the inorganic salt is a sodium silicate, sodium borate or sodium phosphate salt. [0119] 8. A catalyst according to embodiment 7, wherein the inorganic salt is selected from sodium metasilicate pentahydrate, sodium tetraborate, boric acid, and trisodium orthophosphate. [0120] 9. A catalyst according to embodiment 6, wherein the inorganic salt is an ammonium salt. [0121] 10. A catalyst according to any preceding embodiment, comprising less than 1.0% of gold, by weight based on the total weight of the total catalyst. [0122] 11. A catalyst according to any preceding embodiment, comprising no more than 0.1% of gold, by weight based on the total weight of the total catalyst. [0123] 12. A catalyst according to any preceding embodiment, comprising no more than 0.05% of gold, by weight based on the total weight of the catalyst. [0124] 13. A catalyst according to any preceding embodiment, wherein said support comprises carbon. [0125] 14. A catalyst according to any preceding embodiments, wherein said support is in the form of a powder, granulate or shaped unit. [0126] 15. A catalyst according to any preceding embodiment, wherein at least some of the gold is in a positive oxidation state. [0127] 16. A catalyst according to any preceding embodiment, wherein said sulphur-containing ligand is an oxidising ligand containing sulphur in a positive oxidation state. [0128] 17. A catalyst according to embodiment 16, wherein said sulphur-containing ligand is selected from the group consisting of a sulphonate, thiosulphate, thiocyanate, thiourea, thionyl chloride, thiopropionic acid and thiomalic acid. [0129] 18. A catalyst according to any preceding embodiment, comprising sulphur in the range from about 0.005 to 15% by weight based on the total weight of the total catalyst. [0130] 19. A catalyst according to any preceding embodiment, 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. [0131] 20. A method of manufacturing a catalyst according to anyone of embodiments 1 to 19, wherein, [0132] i) a solution of gold is provided, [0133] ii) a solution of sulphur containing ligand is provided, [0134] iii) a solution of an inorganic salt or acid is provided, [0135] iv) the gold solution is mixed with the sulphur containing ligand solution to provide a gold complex impregnation solution, [0136] v) a catalyst support is impregnated with the gold complex impregnation solution, followed by drying the impregnated support, [0137] vi) the catalyst support is impregnated with the inorganic salt or acid, followed by drying the impregnated support. [0138] 21. A method of manufacturing a catalyst according to any one of embodiments 1 to 19, characterised in that, [0139] i) a solution of gold is provided, [0140] ii) a solution of sulphur-containing ligand is provided, [0141] iii) an inorganic salt or acid is added to either the solution of gold, or the solution of sulphur-containing ligand, prior to step iv) [0142] iv) the gold solution is mixed with the sulphur-containing ligand solution, wherein either the gold or sulphur-containing ligand solution also comprises the inorganic salt or acid, to provide a gold complex and inorganic salt or acid containing impregnation solution, [0143] v) a catalyst support is impregnated with the gold complex and inorganic salt or acid containing impregnation solution, followed by drying the impregnated support. [0144] 22. A method in accordance with embodiment 20 or 21, wherein the inorganic salt or acid is derived from a precursor which has been transformed. [0145] 23. A method in accordance with embodiment 22 where the precursor is transformed via a thermal or chemical degradation. [0146] 24. A method in accordance with any one of embodiments 20 to 23, further comprising an activation step. [0147] 25. A chemical process comprising reacting at least one chemical substrate in the presence of a catalyst according to any one of embodiments 1 to 19, or made by a process according to embodiment 20 or 21. [0148] 26. A chemical process according to embodiment 23, comprising the oxidation of said chemical substrate. [0149] 27. A process for the hydrochlorination of an alkyne comprising reacting said alkyne with hydrogen chloride in the presence of a catalyst according to any one of embodiments 1 to 19. [0150] 28. A process for the hydrochlorination of an alkyne, according to embodiment 25, comprising a step of treating said catalyst with hydrogen chloride in the absence of acetylene.