Gold-containing catalysts, methods of preparation, and uses

Abstract

This specification describes a method for producing a hydrochlorination catalyst, comprising the steps of: i) preparing an impregnation solution by combining a gold source and a ligand in a solvent comprising an organic solvent; ii) impregnating a support with the impregnation solution from step (i); and iii) drying the product of step (ii) to obtain a catalyst. Also described is a hydrochlorination catalyst comprising a complex of gold and a ligand of formula (I) supported on a support. These catalysts are particularly suitable for the conversion of acetylene to vinyl chloride monomer.

Description

[Technical field]

[0001] The present invention relates to a gold-containing catalyst, in particular for the conversion of acetylene to vinyl chloride monomer (VCM). [Background technology]

[0002] The hydrochlorination of acetylene to produce VCM as a precursor to polyvinyl chloride (PVC) is currently a large-scale industrial process through the natural gas to acetylene route, particularly in coal-rich and natural gas-rich regions such as China. Over 20,000,000 tonnes of VCM are produced annually by acetylene hydrochlorination, the majority utilizing a mercuric chloride (HgCl2) catalyst supported on activated carbon. Mercury catalysts pose significant environmental problems, up to 0.6 kg Hg / tonne VCM produced, due to volatile HgCl2 subliming from the catalyst bed. Due to the environmental impact of this process, the recently ratified Minamata Convention stipulates that all new VCM plants must use mercury-free catalysts, and that in the near future all existing industrial plants must switch to mercury-free alternatives. This has revived commercial interest in using gold and other metals as catalysts for this reaction.

[0003] From WO 2010 / 055341 (Johnson Matthey PLC and Aker Process BV), it is known that Au-containing catalysts prepared by wet impregnation with a mixture of HAuCl4 / aqua regia are active for the conversion of acetylene to VCM. The catalysts are believed to comprise gold particles with a metallic gold core and a shell of higher oxidation state species including Au(I) and Au(III), which are believed to be the active species for the hydrochlorination reaction.

[0004] WO 2013 / 008004 (Johnson Matthey PLC) describes the development of catalysts based on HAuCl4 by including sulfur-containing ligands such as thiosulfate, which are believed to form complexes with Au atoms, thereby stabilizing Au(I) and Au(III), which are the active species in the hydrochlorination reaction.

[0005] Further developments of the above catalysts are described in WO 2020 / 254817 (Johnson Matthey PLC), in which inorganic oxides, hydroxides, oxo salts or oxo acids are included to improve the catalyst's resistance to carbon nanotube formation.

[0006] VCM catalysts comprising complexes of gold with thiosulfate ligands on carbon supports are marketed by Johnson Matthey under the trademark PRICAT™ MFC. Although these catalysts have been commercially successful, their very high initial activity in the highly exothermic acetylene hydrochlorination reaction needs to be carefully optimized for a particular system. If the initial catalyst activity is too high, localized hot spots can form in the catalyst bed, which can lead to deactivation. There is a need for alternative catalysts that have a more stable activity profile and are less susceptible to initial overheating. The present invention addresses this problem. Summary of the Invention

[0007] The inventors have found that by modifying the manufacturing methods described in WO 2013 / 008004 and WO 2020 / 254817, catalysts with stable activity profiles that are less susceptible to initial overheating can be prepared. The methods exemplified in these references include forming an aqueous impregnation solution containing a complex of gold and a sulfur-containing ligand and applying it onto a carbon support. The inventors have surprisingly found that the initial activity of the catalyst can be reduced by replacing the aqueous solvent of the impregnation solution with an organic solvent or a mixture of an organic solvent and an aqueous solvent. Without wishing to be bound by theory, it is believed that this change changes the wetting between the catalyst and the impregnation solution, which changes the dispersion of the gold complex on the support.

[0008] In a first aspect, the present invention provides a method for producing a hydrochlorination catalyst comprising the steps of: i) preparing an impregnation solution by combining a gold source and a ligand in a solvent comprising an organic solvent; ii) impregnating the support with the impregnation solution from step (i); and iii) drying the product of step (ii) to obtain the catalyst.

[0009] WO 2020 / 016555 (University College Cardiff Consultants Ltd) describes a method for the preparation of a hydrochlorination catalyst by combining gold, an organic solvent and a support material. In the examples of this reference, the catalyst is prepared by impregnation with a solution of HAuCl4·3H2O in an organic solvent. The advantage of this method is that no ligand is required. The method according to the first aspect is similar to the method in WO 2020 / 016555, but requires that the impregnation is carried out using an impregnation solution that contains a ligand in addition to the gold source.

[0010] The method according to the first aspect may be used to prepare complexes similar to those described in WO 2013 / 008004 and WO 2020 / 254817, i.e. complexes in which the ligands are sulfur-containing. However, further advantages in terms of stability can be achieved by replacing the sulfur-containing ligands with ligands of formula (I) described herein.

[0011] In a second aspect, the present invention relates to a catalyst comprising a complex of gold and a ligand of formula (I)

[0012] [ka] (In the formula, X is O or S; n is 1 or 2; R is H or a C1-C10 hydrocarbon group optionally containing one or more heteroatoms selected from halogens (F, Cl, Br, I), oxygen, or nitrogen; The complex is supported on a support.

[0013] A catalyst comprising gold and a ligand of formula I can be prepared as a coordination complex (e.g., a complex of the formula Au[ligand] 4-x Cl x , where x=1-4) or an adduct (e.g., [AuCl3] ligand) is not yet fully understood. This may vary depending on the choice of ligand. As used herein, the term "complex" encompasses both possibilities. For the avoidance of doubt, the oxidation state of Au in the complex may be +1 or +3.

[0014] It is known that complexes of copper and nitrogen-containing ligands can be used as catalysts in the conversion of acetylene to VCM. CN111774094 and CN111715253 (Nankai University) describe a method for preparing copper-based catalysts for vinyl chloride production. The method includes impregnating a carbon support with an impregnation solution containing copper chloride and various additives, which may be nitrogen-containing ligands. CN110743624 (Zhejiang University of Technology) describes a comparative example prepared by combining a solution of CuCl2·2H2O and N-methyl pyrrolidone (NMP) with activated carbon, followed by drying and treatment with hydrogen chloride gas. To the best of our knowledge, a similar complex of gold with NMP has not been described before.

[0015] In a third aspect, the present invention relates to a process for the catalytic hydrochlorination of a substrate containing an alkyne unit, wherein the reaction is carried out in the presence of a catalyst according to the second aspect, or a catalyst prepared or preparable by a method according to the first aspect.

[0016] The process is particularly suitable for producing VCM using acetylene as the substrate. The conversion of acetylene to VCM is preferably carried out in the gas phase. [Brief description of the drawings]

[0017] [Figure 1] 1 shows the activity over time of catalysts E1 to E11. [Diagram 2] 1 shows the activity over time of catalysts E2-1.2, E2-2.0 and E2-4.0. [Diagram 3] NMR spectra of NMP and the complex formed by combining HAuCl4·3H2O and NMP in a 1:4 molar ratio. [Figure 4] 1 shows the activity of catalyst E2-1.2 at various temperatures. [Diagram 5] 1 shows the activity over time of catalysts E12 to E18. [Figure 6]1 shows the activity over time of catalysts E19 (comparison) and E20. [Figure 7] 4 shows the activity over time of catalysts E21 and E22. [Figure 8] The single crystal X-ray structure of [HAuCl4](NMP)2 is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In this specification, all percentages refer to weight percentage of the total catalyst weight, unless otherwise stated.

[0019] Catalyst Production A first aspect of the present invention provides a method for producing a hydrochlorination catalyst, comprising the steps of: i) preparing an impregnation solution by combining a gold source and a ligand in a solvent comprising an organic solvent; ii) impregnating the support with the impregnation solution from step (i); and iii) drying the product of step (ii) to obtain the catalyst.

[0020] It is believed that in step (i) a complex is formed between gold and the ligand. The impregnation solution is preferably prepared by adding the ligand to a solution containing the gold source and the solvent. However, it is also possible to add the gold source to a solution containing the ligand and the solvent. It is also envisaged that the catalyst can be prepared by sequentially treating the support with the gold source and then with the ligand, or vice versa.

[0021] The gold source is typically a gold salt capable of forming a complex with a ligand. A preferred gold source is HAuCl4, either as a solid (e.g., HAuCl4·3H2O) or as a solution (e.g., HAuCl4 in HCl / water).

[0022] The solvent comprises an organic solvent. It is believed that the presence of an organic solvent in the impregnation solution alters the wetting between the impregnation solution and the support, resulting in improved dispersion of gold compared to when an aqueous solution of the gold complex is used as the impregnation solution.

[0023] In some embodiments, the solvent consists of an organic solvent, which may be preferred when both the gold source and the ligand are soluble in the organic solvent.

[0024] In some embodiments, the solvent comprises a mixture of an organic solvent and an aqueous solvent. This may be necessary if either the gold source or the ligand is poorly soluble in the organic solvent. For example, if the gold source is soluble in organic solvent but the ligand is poorly soluble in organic solvent, the ligand may be dissolved in an aqueous solvent and then added to a solution of gold in the organic solvent.

[0025] Suitable organic solvents are described in WO 2020 / 016555, the contents of which are incorporated herein by reference.

[0026] In some embodiments, the organic solvent has an E of 62 or less, e.g., 60 or less, 55 or less, or 50 or less. T (30) It is preferable that the polarity is present. T (30) Polarity is measured by the method described in C. Reichardt, Agnew. Chem. Int. Ed., 1979, 18, pp. 98-110. If the solvent comprises a mixture of organic solvents or is a mixture of organic solvent(s) and water, E T (30) Polarity refers to the solvent as a whole.

[0027] In some embodiments, it is preferred that the organic solvent has a boiling point of 120° C. or less, such as 100° C. or less or 90° C. or less, at 1 atmosphere.

[0028] The organic solvent is preferably selected from the group consisting of alcohols, ketones, esters, ethers, sulfoxides, nitriles, amides, or mixtures thereof.

[0029] Preferred alcohol solvents are methanol, ethanol, propanol and butanol.

[0030] Preferred ketone solvents are acetone, butanone and cyclohexanone, with acetone being a particularly preferred solvent.

[0031] The preferred ester solvent is ethyl acetate.

[0032] Preferred ethereal solvents are diethyl ether and tetrahydrofuran.

[0033] The preferred sulfoxide solvent is dimethyl sulfoxide.

[0034] The preferred amide solvent is dimethylformamide.

[0035] In some embodiments, the ligand is a sulfur-containing ligand. Suitable ligands are described in WO 2013 / 008004, the contents of which are incorporated herein by reference. When the ligand is sulfur-containing, it is preferred that the ligand is selected from sulfonate, thiosulfate, thiocyanate, thiourea or thiol. Preferred ligands include thiosulfate, thiocyanate, thiopropionic acid and thiomalic acid. Thiosulfate is a particularly preferred ligand.

[0036] In an alternative embodiment, the ligand is of formula (I) as defined below in relation to the catalyst.

[0037] The molar equivalents of the ligand of formula (I) added relative to the gold are preferably 1:1 to 1:4, for example 1:1 to 1:2. Including more than 4 equivalents of the ligand does not appear to adversely affect the catalyst performance, but is not preferred for cost reasons. Using 1.2 molar equivalents of the ligand is generally sufficient to fully complex the gold.

[0038] In step (ii), the support is impregnated with the impregnation solution formed in step (i). Impregnation techniques are well known to those skilled in the art.

[0039] In step (iii), the catalyst is dried to remove the organic solvent. Drying techniques are well known to those skilled in the art. A typical procedure involves heating the catalyst at a temperature of 100° C. or higher for 12 hours or more. A gas stream can be used to assist in the removal of the organic solvent. It will be appreciated that the temperature and duration of drying will vary depending on the scale at which the preparation is carried out.

[0040] catalyst The present invention also relates to a catalyst comprising a complex of gold with a ligand of formula (I),

[0041] [ka] (In the formula, X is O or S; n is 1 or 2; R is H or a C1-C10 hydrocarbon group optionally containing one or more heteroatoms selected from halogens (F, Cl, Br, I), oxygen, or nitrogen; The complex is supported on a support.

[0042] It is preferred that X is O. The use of ligands where X is S tends to have lower activity compared to when X is O.

[0043] In one embodiment, R is a C1-C10 hydrocarbon group, such as a C1-C6 hydrocarbon group, containing one or more heteroatoms selected from halogens (F, Cl, Br, I), oxygen (e.g. OH) or nitrogen (e.g. NH2). For example, a C1-C6 hydrocarbyl group or a C1-C3 hydrocarbyl group, in each case containing one or more heteroatoms selected from halogens (F, Cl, Br, I), oxygen (e.g. OH) or nitrogen (e.g. NH2). The presence of heteroatoms in the group R may be beneficial to improve the solubility of the ligand in highly polar solvents.

[0044] In one embodiment, R is a C1-C10 hydrocarbyl group consisting of only C and H atoms, such as a C1-C6 hydrocarbyl group, for example a C1-C6 hydrocarbyl group or a C1-C3 hydrocarbyl group. The absence of heteroatoms in the group R may be beneficial to improve the solubility of the ligand in low polarity solvents.

[0045] It is preferred that R is H or Me, and it is preferred that R is Me. The use of ligands where R is H tends to have lower activity compared to when R is Me.

[0046] It is preferred that n=1.

[0047] Preferred ligands are N-methyl-2-pyrrolidone (NMP) and N-methyl-2-piperidone. These ligands show acetylene conversions that are comparable or better than comparative catalysts containing gold thiosulfate complexes. NMP is a particularly preferred ligand.

[0048] For the avoidance of doubt, NMP has the following structure:

[0049] [ka]

[0050] The role of the ligand is to stabilize Au in the Au(I) or Au(III) oxidation state. The process of the present invention makes it possible to prepare catalysts with high dispersion of Au and a high proportion of Au(I) and Au(III) species, which are believed to be the active species for hydrochlorination.

[0051] The amount of Au added is a trade-off between the cost of Au and the activity of the catalyst. A typical Au content of the catalyst is typically 0.01-5 wt.%, based on the weight of the total catalyst. Typically, the amount of Au added is 0.01-2 wt.%, such as 0.05-1.5 wt.%, for example 0.2-1.5 wt.%.

[0052] In some embodiments, in addition to Au, the catalyst may include one or more promoter metals. The presence of a promoter metal may help improve the activity of the catalyst and / or maintain the activity of the catalyst over time. Suitable promoters include Group 1 and Group 2 metals, as well as cobalt, copper, lanthanum and cerium.

[0053] Any known catalyst support may be used to make the catalyst of the present invention. Typical metal oxide supports such as alumina, silica, zeolites, silica-alumina, titania, or zirconia, and composites thereof may be used. The support is preferably a carbon support. The carbon may be derived from natural sources (e.g., peat, wood, coal, graphite) or may be synthetic carbon. The carbon is preferably activated carbon, e.g., activated carbon that is chemically activated by steam, acid, or other methods.

[0054] The support may be in the form of a powder, granules or shaped particles. Examples of shaped particles include macroscopic catalyst units such as spheres, tablets, cylinders, multi-lobed cylinders (e.g. trilobes), rings, miniliths, etc., or monoliths. Alternatively, the catalyst in powder form may be included in a coating formulation and coated onto a reactor wall or onto a shaped substrate such as a monolith. One preferred form of catalyst support comprises a plurality of shaped units in the form of cylinders, spheres, or lobed cylinders, each having a diameter of 0.1 to 10 mm, or more preferably a diameter in the range of 1 to 3 mm. In the case of cross-sectional shapes with non-uniform diameters, such as lobed cylinders, this diameter is the average diameter. Cylindrical and trilobed shapes are particularly preferred shapes of support.

[0055] Use of catalysts It is envisioned that the catalysts of the present invention are useful in any chemical process in which gold-containing catalysts are known to find utility. The catalysts are particularly suited for the hydrochlorination of compounds containing an alkyne moiety, in particular the conversion of acetylene to VCM.

[0056] The conversion of acetylene to VCM is typically carried out at high temperatures, usually around 100°C to 250°C. The reaction temperature is a balance between conversion and the economics of operating the reactor at higher temperatures. Furthermore, at temperatures significantly above 200°C, coking can become significant. Surprisingly, catalysts containing the ligand of formula (I) are active at lower temperatures than existing Au-based catalysts.

[0057] The HCl and acetylene are preferably premixed and preferably preheated to the reaction temperature. Usually, the HCl is present in an amount in excess of that required for the stoichiometric reaction. The catalyst may be present in the reactor in the form of a fixed bed of catalyst particles arranged so that the feed gas passes over or through the catalyst bed. Alternative reactor configurations may be used, including fluidized beds or other moving bed configurations. Alternatively, the catalyst may be provided in the form of a monolith or coated on the wall of the reactor vessel. The catalyst bed may be provided with a means for regulating the temperature to avoid overheating due to the exothermic reaction or to increase the temperature if necessary. It may be preferable to treat the catalyst with HCl before use in the process. This treatment is typically carried out by flowing HCl over the catalyst for at least 1 hour at a temperature of at least 50° C., more particularly above 100° C. This pretreatment may be carried out in the reactor by operating with a flow of HCl without acetylene at a suitable temperature.

[0058] The present invention also includes the following embodiments. 1. A method for producing a hydrochlorination catalyst, comprising the steps of: i) preparing an impregnation solution by combining a gold source and a ligand in a solvent comprising an organic solvent; ii) impregnating the support with the impregnation solution from step (i); and iii) drying the product of step (ii) to obtain the catalyst. 2. The method of embodiment 1, wherein the solvent comprises an organic solvent. 3. The method of embodiment 1, wherein the solvent consists of a mixture of an organic solvent and an aqueous solvent. 4. The method of any one of the preceding embodiments, wherein the support is a carbon support. 5. The method of any of the preceding embodiments, wherein the organic solvent is selected from the group consisting of alcohols, ketones, esters, ethers, sulfoxides, nitriles, amides, or mixtures thereof. 6. The method of any of the preceding embodiments, wherein the organic solvent comprises or consists of acetone. 7. The method of any one of the preceding embodiments, wherein the ligand is a sulfur-containing ligand. 8. The method of embodiment 7, wherein the sulfur-containing ligand is selected from the group consisting of sulfonates, thiosulfates, thiocyanates, thioureas, or thiols. 9. The method of embodiment 7, wherein the sulfur-containing ligand is a thiosulfate. 10. The ligand is of formula (I),

[0059] [ka] (In the formula, X is O or S; n is 1 or 2; 7. The method of any one of the preceding claims, wherein R is H or a C1-C10 hydrocarbon group optionally containing one or more heteroatoms selected from halogen (F, Cl, Br, I), oxygen or nitrogen. 11. The method of embodiment 10, wherein X is O. 12. The method of embodiment 10 or embodiment 11, wherein R is Me. 13. The method of embodiment 10, wherein the ligand is N-methyl-2-pyrrolidone. 14. The method of any of embodiments 10 to 13, wherein the molar ratio of Au:ligand in step (i) is 1:1 to 1:2. 15. A hydrochlorination catalyst comprising a complex of gold with a ligand of formula (I),

[0060] [ka] (In the formula, X is O or S; n is 1 or 2; R is H or a C1-C10 hydrocarbon group optionally containing one or more heteroatoms selected from halogens (F, Cl, Br, I), oxygen, or nitrogen; A hydrochlorination catalyst, in which the complex is supported on a carrier. 16. The catalyst of embodiment 15, wherein X is O. 17. The catalyst according to embodiment 15 or embodiment 16, wherein R is H. 18. The catalyst according to embodiment 15 or embodiment 16, wherein R is Me. 19. The catalyst according to embodiment 15, wherein the ligand is N-methyl-2-pyrrolidone. 20. The catalyst of any one of embodiments 15 to 19, wherein the molar ratio of Au:ligand is from 1:1 to 1:4. 21. The catalyst according to any one of embodiments 15 to 20, wherein the content of Au in the catalyst is 0.01 to 5 wt.%. 22. The catalyst of any one of embodiments 15 to 21, wherein the support is in the form of a powder, granules, or shaped particles. 23. The catalyst according to any one of embodiments 15 to 22, wherein the support is a carbon support. 24. A process for the catalytic hydrochlorination of a substrate containing an alkyne unit, wherein the reaction is carried out in the presence of a catalyst according to any one of embodiments 15 to 23 or a catalyst preparable by the method according to any one of embodiments 1 to 14. 25. The process of embodiment 24, wherein the substrate is acetylene. EXAMPLES

[0061] General procedure for catalyst testing A sample of catalyst (~90 mg) was loaded onto glass wool in a reaction tube. The feed stream was prepared by combining 24.00 mL / min of C2H2 (5% acetylene in argon), 30.00 mL / min of HCl (5% HCl in argon), and 4.10 mL / min of argon. The temperature of the feed stream was set at 180°C unless otherwise stated. Acetylene conversion was measured by gas chromatography.

[0062] Example 1 - Preparation of Ligand-Free Comparative Catalyst (E1) Catalyst E1 was prepared by the impregnation method. Activated carbon (NORIT ROX 0.8) was first ground and sieved (150 mesh) to obtain a powder with a particle size less than 150 μm. The gold precursor, HAuCl4·3H2O (solid from Alfa Aesar, 20 mg, assay 49%), was dissolved in dry acetone (2.7 mL) and stirred for 10 min. This solution was added dropwise to the ground, activated, dry carbon powder (0.99 g) with stirring. The solution was stirred at room temperature for 1 h and finally dried at 45 °C under nitrogen for 16 h.

[0063] Examples 2 to 11 - Role of the Ligand Examples 2-11 reported in Table 1 were prepared by the same method as described for Example 1, with the following modifications: The ligand was weighed into a vial. An acetone solution of HAuCl4·3H2O was added to the ligand, and the resulting solution was used for impregnation of carbon powder as described in Example 1. The Au:ligand (mol:mol) ratio was 1:1.2, 1:2, or 1:4. The final Au loading was 1 wt%.

[0064] [Table 1]

[0065] These catalysts were tested for their acetylene conversion according to the general procedure, and the results are shown in Figure 1. All catalysts were deactivated during the course of the test, except for E1 (no ligand), E2-1.2 (NMP) and E10 (benzyl isothiocyanate).

[0066] The role of ligand equivalents The role of ligand equivalents for E2-1.2, E2-2.0 and E2-4.0 is compared in Figure 2. Performance was similar, but generally E2-4.0>E2-2.0>E2-1.2.

[0067] NMP in d6-acetone and E2-4.0 prepared in d6-acetone 1An overlay of the 1 H NMR spectra is shown in Figure 3. All of the peaks associated with NMP are shifted in the complex, suggesting that NMP is coordinated.

[0068] The role of temperature The activity of Example E2-1.2 was tested at temperatures of 30, 65, 120, 180, 200 and 220° C. The results are shown in FIG. 4. The activity increased with increasing temperature. The acetylene conversion was highest at 220° C., but the amount of acetylene converted did not correspond to the amount of VCM produced. This discrepancy is believed to be related to the formation of coke at high temperatures.

[0069] Examples 12-18 - Alternative Ligands The catalysts in Table 2 were prepared following the same procedure as Examples 2 to 11, using 1.2 equivalents of ligand. The final Au loading was 1 wt%.

[0070] [Table 2]

[0071] These catalysts were tested for their acetylene conversion according to the general procedure. The results are shown in Figure 5. Catalyst E2-1.2 containing NMP ligand showed the highest activity of all catalysts and had a relatively stable activity over time. Catalyst E12 containing N-methyl-2-piperidone ligand also showed good activity and was relatively stable, but was slightly less active than E1 containing thiosulfate ligand.

[0072] The other catalysts were less active and showed gradual deactivation from the start in the case of E13 containing 2-pyrrolidinone and E15 containing 1-methylpyrrolidine.

[0073] Examples 19 and 20 - Role of Solvent Catalysts containing in each case 1% Au complexed with thiosulfate ligand were prepared by the following procedure.

[0074] Activated carbon (NORIT ROX 0.8) was ground to powder and sieved to less than 180 microns. Ammonium thiosulfate (0.975 g) and CaCl2 (0.175 g) were dissolved in 17 mL of demineralized water. HAuCl4 solution (Johnson Matthey, 0.25 g Au, assay 41.76%) was diluted with 17 mL of demineralized water and this solution was added to the ammonium thiosulfate-containing solution. Carbon powder (dry weight 24.75 g) was impregnated with the gold-containing solution by incipient wetness technique. The impregnated mass was left for 1 hour and then dried in air at 105°C for 16 hours to obtain catalyst E19.

[0075] Activated carbon (NORIT ROX 0.8) was ground to powder and sieved to less than 180 microns. Ammonium thiosulfate (0.975 g) was dissolved in 15 mL of demineralized water. HAuCl4 solution (Johnson Matthey, 0.25 g Au, assay 41.76%) was diluted with 25 mL of acetone and this solution was added to the ammonium thiosulfate-containing solution. Carbon powder (dry weight 24.75 g) was impregnated with the gold-containing solution by incipient wetness technique. The impregnated mass was left in flowing air at room temperature for 12 hours and then dried in air at 105°C for 16 hours to obtain catalyst E20.

[0076] Catalytic testing was performed using a fritted reactor tube. 150 mg of SiC was placed on the frit, followed by 300 mg of catalyst. A sample of the catalyst (approximately 300 mg) was loaded onto glass wool in the reactor tube. The feed stream was prepared by combining (5.83 mL / min of acetylene (5% acetylene in argon)) and 6.03 mL / min of HCl (5% HCl in argon). The temperature of the feed stream was set at 180° C. unless otherwise stated. Acetylene conversion was measured by gas chromatography. The results are shown in FIG. 6.

[0077] The catalyst (E19) prepared using an impregnation solution containing 1% Au showed an initial conversion of about 70% and stabilized at about 45% conversion, which was about 65% of the initial activity.

[0078] In contrast, the catalyst prepared using the acetone / water impregnation solution (E20) initially showed about 50% conversion and stabilized at about 45% conversion. The stable value was about 90% of the initial activity. This catalyst showed a much more stable activity profile without high initial activity. This is expected to be advantageous in avoiding local hot spots in the initial activation of the catalyst.

[0079] Examples 21 and 22 - Alternative Sulfur-Containing Ligands A catalyst containing 1% Au (E21) was prepared following the procedure used to prepare E20, except that the aqueous solution of ammonium thiosulfate was replaced with a solution of sodium thiocyanate (0.530 g) in 25 mL of acetone. The solution of HAuCl4 was diluted with 15 mL of acetone instead of 25 mL. The solutions were mixed together and used immediately to impregnate carbon powder.

[0080] A catalyst containing 0.5% Au (E22) was prepared according to the procedure used to prepare E21, except that 0.125 g Au as a HAuCl4 solution was used instead of 0.25 g Au as a HAuCl4 solution.

[0081] The aqueous solution of ammonium thiosulfate was replaced with a solution of sodium thiocyanate (0.530 g) dissolved in 25 mL of acetone. The solution of HAuCl4 was diluted with 15 mL of acetone instead of 25 mL. The solutions were mixed together and used immediately to impregnate carbon powder.

[0082] The results are shown in Figure 7. In each case, the catalysts exhibited stable activity profiles without an initial spike in catalytic activity, which is expected to be advantageous in avoiding localized hot spots during the initial activation of the catalyst.

[0083] Preparation of [HAuCl4](NMP)2 Acetone (15 mL) was added to a solution of 2.50 g of HAuCl4 (40.02% Au) containing 1.00 g of Au. To this solution was added a solution containing 4 molar equivalents of N-methylpyrrolidine (2.01 g) in 15 mL of acetone. The resulting solution was mixed and allowed to react for 30 minutes, after which the solution was evaporated under vacuum to give an oily residue. After washing with an aliquot of cyclohexane, a solid product was obtained which was recrystallized from 1-propanol-cyclohexane to give a crop of fine bright yellow needles in high yield. Single needle crystals suitable for X-ray crystallography were obtained by slow crystallization from 1-propanol-cyclohexane.

[0084] AuC 10 Cl4H 19 Calculated elemental analysis for N2O2 required Cl 26.4%, C 22.3%, H 3.6%, N 5.2% and was found to be Cl 26.4%, C 22.3%, H 3.5%, N 5.2%.

[0085] Single crystal structure determination by X-ray diffraction analysis at 296 K using radiation with a wavelength of 0.71073 Å showed that the material has the following properties: monoclinic, space group P21 / n, a = 14.2719(8) Å, b = 7.6086(5) Å, c = 16.5447(15) Å), α = 90°, β = 98.485(7)°, γ = 90°, Z = 4, crystal dimensions 0.380 × 0.140 × 0.090 mm. 3 A total of 4383 independent reflections were collected.

[0086] An image of the measured structure showing the NMP coordination around the AuCl4 center is shown in Figure 8. The N-Au distances were 3.726 Å and 3.929 Å.

Claims

1. 1. A method for producing a hydrochlorination catalyst, comprising: i) preparing an impregnation solution by combining a gold source and a ligand in a solvent, wherein the solvent comprises an organic solvent that includes or consists of acetone; ii) impregnating a support with the impregnation solution from step (i); iii) drying the product of step (ii) to obtain the catalyst; The ligand is of formula (I): 【Chemical 1】 (In the formula, X is O or S; n is 1 or 2; R is H or a C1-C10 hydrocarbon group optionally containing one or more heteroatoms selected from halogen (F, Cl, Br, I), oxygen or nitrogen.

2. The method of claim 1 , wherein the solvent consists of the organic solvent.

3. 10. The method of claim 1, wherein the solvent comprises a mixture of an organic solvent and an aqueous solvent.

4. The method of any one of claims 1 to 3, wherein the ligand is N-methyl-2-pyrrolidone.

5. 1. A hydrochlorination catalyst comprising a complex of gold with a ligand of formula (I), 【Chemistry 2】 (In the formula, X is O or S; n is 1 or 2; R is H or a C1-C10 hydrocarbon group optionally containing one or more heteroatoms selected from halogen (F, Cl, Br, I), oxygen, or nitrogen; A hydrochlorination catalyst, wherein the complex is supported on a carrier.

6. The catalyst of claim 5, wherein the ligand is N-methyl-2-pyrrolidone.

7. 7. The catalyst of claim 5 or 6, wherein the support is in the form of a powder, granules or shaped particles.

8. 7. The catalyst according to claim 5, wherein the support is a carbon support.

9. 10. A process for the catalytic hydrochlorination of a substrate containing an alkyne unit, wherein the reaction is carried out in the presence of a catalyst according to claim 5 or a catalyst preparable by the process according to claim 1.

10. 10. The process of claim 9, wherein the substrate is acetylene.

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