Recycling of components of supported palladium and platinum catalysts.

Abstract

A method for recycling a supported palladium catalyst or a supported platinum catalyst comprising palladium or platinum and a base metal disposed on a ceramic support, the method comprising: leaching the palladium or platinum and the base metal from the ceramic support using a hydrochloric acid leach solution to produce a hydrochloric acid leach solution containing palladium or platinum and the base metal; passing the leach solution through a column comprising a material that selectively adsorbs palladium or platinum; eluting the palladium or platinum from the column using an eluent to produce a solution containing palladium or platinum; and treating the solution containing palladium or platinum to recover the palladium or platinum.

Description

[Technical Field]

[0001] This specification relates to a method for recycling components of supported palladium and platinum catalysts. [Background technology]

[0002] Catalysts comprising one or more platinum group metals (PGMs) are well known to be useful in a wide range of applications. One or more PGMs can also be combined with one or more base metals to provide mixed metal catalysts. Additionally, PGM catalysts can be provided on a support material, such as a ceramic support material, to provide a supported catalyst material.

[0003] Palladium and platinum catalysts are particularly useful in certain applications. As generally discussed above for PGM catalysts, such catalysts may include palladium or platinum in combination with one or more base metals (or non-PGMs), and such catalysts may be provided on a support material, such as a ceramic support.

[0004] As the demand for PGMs increases, so does the need to recycle and reuse these materials. Furthermore, there is a growing need to achieve recycling of PGMs in a more energy-efficient, economical, sustainable and environmentally friendly manner. Furthermore, there is a need to recycle PGMs from multi-component materials in a manner that allows for the recycling of one or more other components, for example, the support material of supported PGM catalysts.

[0005] In regard to the above, recovery of platinum group metals (PGMs) from supported catalyst materials is typically achieved by smelting, which involves heat treating the supported PGM material, is energy intensive, costly, and can cause environmental damage and pollution. In the case of mixed metal catalysts, such smelting processes can result in mixed metal alloys that require significant further processing to extract and purify the PGM components. Furthermore, such smelting processes can damage the support material, rendering it unsuitable for reuse.

[0006] The purpose of this document is to address these issues. Summary of the Invention

[0007] The present specification provides a method for recycling a supported palladium catalyst or a supported platinum catalyst comprising palladium or platinum and a base metal disposed on a ceramic support, the method comprising: leaching palladium or platinum and a base metal from the ceramic support using a hydrochloric acid leachate to produce a hydrochloric acid leachate containing palladium or platinum and a base metal; passing the leachate through a column containing a material that selectively adsorbs palladium or platinum; eluting the palladium or platinum from the column with an eluent to produce a solution comprising palladium or platinum; treating the solution containing palladium or platinum to recover the palladium or platinum.

[0008] This process has the potential to recover palladium or platinum and reuse the ceramic support via a hydrometallurgical route. Supported palladium / platinum catalysts do not require heat treatment, providing a more sustainable recycling route compared to smelting. The ceramic support can be a metal oxide, metal nitride, or metal carbide material. An advantage of the exemplary method of the present invention is that the ceramic support does not undergo thermal or chemical decomposition treatment. Therefore, after leaching the palladium or platinum and base metals from the ceramic support, the ceramic support can be recovered and reused.

[0009] The base metal may include two or more base metals. For example, the base metal may include or consist of one or more transition metals and / or one or more post-transition metals. Examples include tin and / or molybdenum. The ceramic support may include or consist of zirconia. It has been found that leaching palladium / platinum and base metals, such as tin and molybdenum, from a ceramic support, such as zirconia, using a hydrochloric acid leachate can produce a hydrochloric acid leachate containing palladium / platinum and the base metals. Furthermore, the ceramic support can be recovered and reused.

[0010] It has further been found that commercially available ion exchange / molecular recognition materials can be used in columns to selectively adsorb palladium / platinum from the leachate using base metals that pass through the column. The palladium / platinum can then be eluted from the column and recovered, for example, by precipitating as palladium / platinum salts. This method thus allows for the recovery of both palladium / platinum and the ceramic support (and optionally the base metal) using a hydrometallurgical route that avoids smelting and processing that would damage the support material.

[0011] The hydrochloric acid leachate may have a hydrochloric acid concentration of at least 1M, 2M, or 3M and not more than 8M, 7.5M, or 7M, or within a range defined by any combination of the aforementioned lower and upper limits. The hydrochloric acid leachate may further include an oxidizing agent, such as hydrogen peroxide or chlorate. The leaching process may be carried out at a temperature of at least 20°C, 30°C, or 40°C and not more than 95°C, 80°C, or 70°C, or within a range defined by any combination of the aforementioned lower and upper limits. Furthermore, the supported palladium catalyst / platinum catalyst may be crushed or milled prior to leaching. Crushing or milling the supported palladium catalyst / platinum catalyst can reduce the need for an oxidizing agent. It should be noted that while crushing or milling can reduce the particle size of the ceramic support material, the material is not thermally or chemically degraded and therefore can still be recycled.

[0012] The column used to selectively adsorb palladium / platinum from the leachate can contain a polymeric ion exchange resin / molecular recognition resin, such as a commercially available SuperLig™ resin (e.g., SuperLig™ 2 resin for selective Pd extraction). The palladium / platinum can then be recovered from the column. For example, palladium can be recovered by precipitation as the Pd(NH)Cl salt after elution with (NH)SO or NHHSO, for example, by treating the eluate with HCl and HO.

[0013] After leaching the palladium / platinum and base metals from the ceramic support, the ceramic support can be recovered and reused. [Brief explanation of the drawings]

[0014] For a better understanding of the invention and to show how the same may be carried into effect, certain embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1]1 shows a graph of metal leaching (%) versus acid molarity for palladium, tin, and molybdenum. [Figure 2] 1 shows a graph of metal leaching mass versus volume of oxidant added for palladium, tin, and molybdenum. [Figure 3] 1 shows a graph of % metal leached versus volume of oxidant added for palladium, tin, and molybdenum. [Figure 4] The supported catalyst (palladium, tin, and molybdenum on zirconia) is shown before leaching. [Figure 5] Catalyst of FIG. 4 after leaching. [Figure 6] 1 shows a graph of leached metal concentration versus time during an initial leach using HCl only, followed by a leach using HCl and sodium chlorate. [Figure 7] 1 shows a graph of metal leaching (%) versus time during an initial leach using HCl only, followed by a leach using HCl and sodium chlorate; and [Figure 8] 1 shows a graph of metal leaching (%) versus volume of H2O2 added. DETAILED DESCRIPTION OF THE INVENTION

[0015] As described in the Overview section, the present specification provides a method for recycling a supported palladium catalyst or a supported platinum catalyst comprising palladium or platinum and a base metal disposed on a ceramic support, the method comprising: leaching palladium or platinum and a base metal from the ceramic support using a hydrochloric acid leachate to produce a hydrochloric acid leachate containing palladium or platinum and a base metal; passing the leachate through a column containing a material that selectively adsorbs palladium (e.g., an ion exchange resin or a molecular recognition resin); eluting the palladium or platinum from the column with an eluent to produce a solution comprising palladium or platinum; treating the solution containing palladium or platinum to recover the palladium or platinum.

[0016] This process offers the potential for recovering palladium or platinum and reusing the ceramic support via a hydrometallurgical route. The supported palladium / platinum catalyst does not require heat treatment, and the ion exchange / molecular recognition column can be reused for hundreds of cycles before replacing the ion exchange / molecular recognition resin, providing a more sustainable recycling route compared to smelting.

[0017] This process has been exemplified for a catalyst comprising Pd / Sn / Mo supported on zirconia. It has been demonstrated that Pd / Sn / Mo can be leached in HCl (0-8M) with or without the addition of an oxidizing agent such as hydrogen peroxide or chloric acid. The process can be carried out at temperatures ranging from 20-95°C, and the catalyst material can be treated as received or by crushing or milling prior to leaching.

[0018] After leaching, the leachate can be concentrated (e.g., by boiling) and passed through an ion exchange / molecular recognition resin such as SuperLig™ 2; Pd is retained on the resin, while Sn and Mo pass through the column. Pd can then be removed from the column, for example, using ammonium sulfite. The Pd ammonium sulfite solution can then be treated with HCl and hydrogen peroxide, and Pd precipitates as diamminedichloropalladium.

[0019] The process can be carried out as a batch or continuous process. Catalyst leaching can be carried out by packing the catalyst into a column and then circulating / recirculating the acid leachate through the column.

[0020] This process allows for a Pd or Pt recovery route for supported Pd (or Pt) / base metal catalysts, such as catalysts comprising Pd / Sn / Mo supported on zirconia. [Example]

[0021] Example 1: Leaching of catalytic materials (palladium, tin, and molybdenum on zirconia) with various HCl molarities 40.2 g of spent catalyst (palladium, tin, and molybdenum on zirconia) was weighed directly into a 1 L flat-bottom, baffled, borosilicate flanged glass reactor. After adding 400 mL of demineralized water, an overhead stirrer was inserted and a five-port borosilicate glass lid was attached and clamped in place. The stirrer was attached to an overhead stirrer motor, and the reactor was clamped in place. Three of the five ports were closed with glass stoppers. The stirrer was submerged approximately 3 cm from the bottom of the reactor. The experiment was conducted at room temperature. The reactor contained the supported catalyst (palladium, tin, and molybdenum on zirconia) in demineralized water prior to the addition of HCl.

[0022] The stirrer was set to 300 rpm. There was a slight visual change from clear to cloudy, likely due to the presence of fines within the material, and some air bubbles were released. A sample was taken after 20 minutes. To take the sample, the stirrer motor was stopped and 5 mL was measured using a plastic pipette into a 5 mL graduated cylinder and transferred to a sample vial.

[0023] After the first sample was taken, a first addition of 20 mL of 37% HCl from a graduated cylinder was made through one of the open ports. An immediate color change from cloudy to pale orange was visible. The reaction mixture was allowed to stand for 10 minutes and then sampled.

[0024] The addition of 20 mL of HCl was repeated 11 more times at 10 minute intervals, with 5 mL samples taken as before before the acid addition.

[0025] During these additions the color gradually darkened through a more intense orange to brown to brown-green, then became so dark in the reactor that it was difficult to discern the color change.

[0026] Starting with the 13th addition, the acid volume was increased to accommodate a larger total volume and increase the molarity during each addition: 13th addition = 30 mL; 14th addition = 35 mL; 15th addition = 40 mL; 16th addition = 45 mL; 17th addition = 50 mL. The reaction vessel was subjected to stepwise addition of HCl before filtration. During the stepwise addition of HCl, a series of samples were taken from the reaction vessel for subsequent metal content analysis.

[0027] After the final acid addition sample was taken, the stirrer motor was stopped and the reaction was allowed to stand for approximately 30 minutes before being filtered by vacuum filtration through a 7 cm diameter GF / F (0.7 μm porosity) filter into a 1 L Buchner flask. This took approximately 5 minutes. The solution was weighed, the volume measured, and then transferred to a 1 L bottle (net volume 711 mL, net weight 781.15 g). A sample of the final filtrate was taken.

[0028] The same filter and Buchner flask were used to wash the remaining solids and rinse the solution from the associated glassware. This was left to dry for approximately 5 minutes until the sample appeared clean and dry. The wash liquid was clear with a pale orange color. These were weighed, the volume was measured, and then transferred to a 500 mL bottle (net weight 291.63 g and net volume 290 mL).

[0029] All samples were sent for metal content analysis by ICP (inductively coupled plasma) spectroscopy. Figure 1 shows a graph of metal leaching (%) versus acid molarity for palladium, tin, and molybdenum. It is noteworthy that the base metals (Sn and Mo) were leached along with the palladium, and selective leaching of palladium was not achieved. Therefore, these tests indicated that palladium and the base metals should be leached together and then separated from the base metals to recover the palladium, for example, via reduction to Pd metal or via precipitation as a Pd salt.

[0030] Example 2: HCl leaching of catalytic materials using H2O2 as the oxidizing agent Following the previous example, the objective is to strip all, or at least substantially all, of the Pd, Mo, and Sn from the zirconia base of the spent catalyst material using 7 M HCl and oxidant (H2O2) at a maximum flow rate of 0.17 mL / min.

[0031] 35 g of catalyst material was weighed into a 500 mL flange vessel and placed on a hot plate equipped with an overhead stirrer, condenser, and temperature probe. 350 mL of 7 M HCl was added to one of the available ports using a glass funnel, and the temperature was set to 70°C. The Gilson pump was set to a pumping flow rate of 0.5 (0.05 mL / min). Tubing was prepared and inserted into an available port via a connector and sealed with parafilm. The overhead stirrer was set to 150 rpm.

[0032] After reaching a temperature of 70°C, peroxide addition was begun at the minimum rate and monitored to ensure the reaction was not excessively foamy. After 5 minutes, the peroxide addition rate was increased to 0.75 (0.08 mL / min), then to 1 (0.11 mL / min) after 17 minutes, then again to 1.25 (0.14 mL / min) after 15 minutes, and finally to 1.5 (0.17 mL / min) after 30 minutes.

[0033] The reaction was continued for 3.5 hours at a flow rate of 0.17 mL / min. Samples were taken before H2O2 addition and then every hour. Further samples were taken after cooling, and a final sample was taken after filtration. The resulting solution was filtered through GF / F filter paper into a Buchner funnel by vacuum filtration. The residue was dried under vacuum for 10 minutes and then air-dried.

[0034] Seven samples were analyzed by ICP spectroscopy. Figure 2 shows a graph of metal mass leached versus volume of oxidant added for palladium, tin, and molybdenum, and Figure 3 shows a graph of metal leaching (%) versus volume of oxidant added for palladium, tin, and molybdenum.

[0035] The results show increased leaching of all metals when using a combination of hydrogen peroxide and HCl compared to using HCl alone. 80% of the Pd and Sn were removed with the first 8 mL of peroxide (about 1 hour), followed by another 10% with about 3 hours or 30 mL of peroxide. This process can remove virtually all metals when carried out for longer periods of time.

[0036] Example 3: HCl leaching of catalytic materials using sodium chlorate as the oxidant Leaching of a Pd / Mo / Sn / zirconia material using hydrochloric acid and sodium chlorate as oxidizing agents is described in this example.

[0037] 7 mol / L hydrochloric acid was prepared by diluting 585 mL (7 mol) of 37% (w / w) concentrated analytical reagent grade hydrochloric acid in a 1 liter volumetric flask. The solution was made up to volume with demineralized water and shaken to ensure homogeneity. The density of the prepared acid was 1.11 g / cm 3 It was.

[0038] 400 mL of 7 mol / L hydrochloric acid was weighed into a 500 mL flat-bottom, baffled (x3) borosilicate glass reactor. The 5-port borosilicate glass lid was clamped in place, and the reactor was placed on a hot plate. A stirrer guide was connected to the center port, through which a 5 cm diameter Teflon™-coated, pitched-blade (downward flow) impeller was submerged in the acid approximately 1 cm from the bottom of the vessel. The impeller shaft was connected to an overhead stirrer motor.

[0039] The temperature was controlled by a thermostat connected to a hot plate and a Teflon™ probe in the solution. The volume was kept constant by using a spiral reflux condenser connected to a port in the reactor lid. Unused ports were plugged. Teflon™ joint clips were used to prevent the ground glass adapter from loosening.

[0040] The catalyst sample (40.12 g) was slowly charged through a glass funnel into the acid stirred at 300 rpm at 19° C. After the addition was complete, the funnel was removed and replaced with a stopper. A few bubbles were observed during the addition, some immediate dissolution occurred, and the solution turned pale orange. The temperature was maintained constant during the addition of the solid, and the addition was complete in less than 5 minutes.

[0041] Thus, the apparatus was set up to leach metals from the supported catalyst using HCl. Upon heating to 95°C (which took 45 minutes), the solution darkened to a deep orange color, indicating that further dissolution had occurred. A sample (5 mL) was taken using a 0.45 μm syringe filter disk to remove solids. The reaction was then allowed to continue for an additional 90 minutes, with samples taken at 45 and 90 minutes. There was no visible color difference between the samples.

[0042] Because there was no visible color difference between samples taken between 45 and 90 minutes, sodium chlorate was added to ensure the leaching of residual palladium. Narrow-bore (0.8 mm) tubing was connected to a peristaltic pump to deliver a 450 g / L sodium chlorate solution from a graduated cylinder. The sodium chlorate line was primed for air removal, and the tubing was attached to a connector and placed in a port on the vessel lid. A nitrogen line was added with a flow rate set at 1.0 L / min. This modified setup was used to leach metals from supported catalysts using HCl with added sodium chlorate.

[0043] Sodium chlorate addition was initially started at 0.5 mL / min, but this was too rapid, as evidenced by the large amount of chlorine evolved. After the first 5 minutes, a sample was taken and the chlorate addition rate was reduced to 0.25 mL / min. Further samples were taken 55 and 175 minutes after chlorate addition. The mixture was then stirred for approximately 1 hour, while cooling under a nitrogen stream, until the leachate temperature reached 40°C.

[0044] The leachate was filtered by vacuum through a 7 cm diameter GF / F (0.7 μm porosity) filter into a 1 L Buchner flask, then transferred to a 500 mL bottle, shaken, and sampled.

[0045] A second 1 L flask was used to collect the demineralized water wash from the reactor to aid in transfer and to wash the solids. The total wash volume was 183 mL. The wash appeared slightly cloudy. The leached catalyst was then dried and weighed (41.11 g).

[0046] FIG. 4 shows the supported catalyst before leaching, and FIG. 5 shows the catalyst after leaching.

[0047] Leachate samples were analyzed using ICP spectroscopy. Figure 6 shows a graph of leached metal concentration versus time during an initial leaching using HCl only, followed by leaching using HCl and sodium chlorate. Figure 7 shows a graph of metal leaching (%) versus time during an initial leaching using HCl only, followed by leaching using HCl and sodium chlorate.

[0048] The results show that hydrochloric acid (7M) is a suitable leaching agent for dissolving Pd from the support at 95°C under reflux conditions. Leaching efficiencies for Pd (78%), Sn (69%), and Mo (54%) were all high and all exhibited fast rates. The ZrO2 support remained virtually insoluble throughout. The addition of sodium chlorate showed improved leachability for Pd (86%) and Sn (77%).

[0049] Example 4: HCl / H2O2 leaching of crushed catalyst material The objective of this example is to leach all or substantially all of the Pd, Mo, and Sn from the zirconia base of the catalyst using 7 M HCl and H2O2 at a maximum flow rate of 0.17 mL / min. The catalyst material is crushed prior to leaching.

[0050] 34 g of spent catalyst was weighed, transferred to a clean pestle and mortar, and crushed. After crushing, the material was transferred to a 500 mL flanged vessel and weighed by difference. 33.21 g was used for leaching. 330 mL of 7 M HCl was added to the flanged vessel through one of the open ports, and the temperature was set to 70°C. Other ports included a condenser, an overhead stirrer, tubing for hydrogen peroxide addition, and two stoppered ports.

[0051] The Gilson pump was set to a pumping rate of 1.25 (0.14 mL / min). Tubing was prepared and inserted into an available port via the connector and sealed with parafilm. The overhead stirrer was set to 150 rpm. After reaching a temperature of 70°C, the peroxide addition was started and the reaction was monitored to ensure it was not too foamy.

[0052] After 3 minutes, there was no excessive reaction, so the peroxide addition rate was increased to 1.5 (0.17 mL / min). The reaction continued for 2 hours at a rate of 0.17 mL / min, then accelerated to 1.75 (0.2 mL / min). Peroxide addition continued at 0.2 mL / min for another hour, then increased to 2 (0.23 mL / min) over the final hour. Samples were taken before the H2O2 addition and then every hour. Further samples were taken after cooling, and a final sample was taken after filtration. All samples for analysis were filtered through a 0.45 μm SFCA filter. The resulting solution was filtered by vacuum filtration through GF / F filter paper into a Buchner funnel. The residue was dried under vacuum for 10 minutes and then air-dried.

[0053] The samples were analyzed using ICP spectroscopy. Figure 8 shows a graph of metal leaching (%) versus volume of H2O2 added.

[0054] Crushing the spent catalyst increased the available surface area, allowing more metals to be leached into the acid before the addition of peroxide, as shown in Figure 8. Furthermore, crushing allowed peak metal leaching to be reached earlier and with less peroxide.

[0055] Example 5: Varying the parameters for leaching Samples of supported catalyst material were subjected to leaching in both crushed and uncrushed forms at a number of different temperatures (20°C, 70°C, 95°C). The method involved weighing 30 g of spent catalyst into a 500 mL baffled flange-top vessel equipped with an overhead stirrer, a port to allow for H2O2 addition, a PTFE temperature probe, and two stoppered ports. Samples were taken after 1 hour of leaching without oxidant and after an additional hour of leaching using hydrogen peroxide as the oxidant. Both acid and water washed samples were also obtained. All samples were analyzed by ICP spectroscopy. The results are summarized in the table below.

[0056] [Table 1]

[0057] [Table 2]

[0058] The results show that palladium can be leached using HCl over a range of temperatures, and that crushing the catalyst material or using an oxidizing agent is not essential, although there are some advantages to crushing and using an oxidizing agent as described above. It is envisioned that the solids loading can be increased (e.g., to 20% or 30%) and that the leachate can be recycled with unleached spent catalyst to concentrate the leachate.

[0059] Example 6: Treatment of leachate to recover palladium The leachate and wash solutions from the previous example were combined and boiled to concentrate the solution, which was then passed through a column packed with an ion exchange medium / molecular recognition medium to separate Pd from base metals, particularly Sn.

[0060] The leachate and wash solutions were combined in a 2-L beaker and stirred for 30 minutes. A sample was taken for analysis. Approximately half of the solution was transferred to a 2-L round-bottom flask and placed in a distillation apparatus set at a mantle temperature of 180°C (vapor temperature of 105-110°C), and the flask was refilled until all the solution had been added. The solution was boiled until approximately 100 mL remained, and then further diluted to 160 mL with 6 M HCl.

[0061] 16.05 g of SuperLig™ 2 resin was weighed into a beaker and mixed with approximately 10 mL of 6 M HCl. After allowing the resin to soak briefly, it was transferred to a column (35 mm diameter with two adjustable end pieces), the excess acid was drained off, and the column was filled to a bed height of 2.7 cm and 25.96 cm. 3 A bed volume of 1000 ml was left. The feed (5.5 g / L Pd) was filtered under vacuum through a 0.45 μm PVDF membrane before passing through the column. The feed was introduced into the column at 1.5 mL / min (Gilson Mini Pump 3 set at 25.5) with the intention of overloading by 110%. 160 mL of feed was passed through the column and the raffinate was collected and sampled. A 6 M HCl wash was passed through the column at 1.5 mL per minute, followed by a water wash at the same flow rate. These fractions were pooled together and sampled.

[0062] 1M ammonium sulfite was passed through the column to elute Pd at a flow rate of 0.75 mL / min, and the strip was collected as a Pd(NH3)(SO4) solution. The column was again washed with water and 6M HCl at a flow rate of 0.75 mL / min, and these fractions were collected and sampled. The Pd(NH3)(SO4) solution was then treated with HCl and H2O2 to precipitate palladium as the Pd(NH3)2Cl2 salt. Recovery of palladium as the precipitated Pd(NH3)2Cl2 salt was thus achieved. An example of how to use Superlig™2 is published by IBC Advanced Technologies, Inc. (See, e.g., Izatt, SR; Bruening, RL; Izatt, NE, "Green Chemistry Approach to Platinum Group Metals Refining," International Precious Metals Institute, 38th Annual Conference, Orlando, FL, June 7–10, 2014; "Selective Recovery of Platinum Group Metals and Rare Earth Metals from Complex Matrices Using a Green Chemistry / Molecular Recognition Technology Approach," Metal Sustainability: Global Challenges, Consequences, and Prospects, First Edition. Edited by Reed M. Izatt, © 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd.; and other publications from IBC Advanced Technologies, Inc.) A mass balance of the output indicated a Pd recovery of 99.2%. Furthermore, the precipitated Pd(NH3)2Cl2 salt met market-grade specifications.

[0063] It should also be noted that while the process herein is exemplified for supported palladium catalysts, the technology described herein can also be used to recycle supported platinum catalysts using an acid leaching process followed by platinum recovery using a different ion exchange / molecular recognition resin selective for platinum. For example, a publication by IBC Advanced Technologies, Inc. discloses Superlig™ resins, which are selective for platinum over palladium, and can be used in conjunction with an acid leaching process as described herein to recover platinum from ceramic-supported platinum catalysts without the need for refining. Thus, the present disclosure also enables platinum recovery via a hydrometallurgical route with the potential for reuse of the ceramic support, enabling a more sustainable recycling route for both ceramic-supported platinum catalysts and ceramic-supported palladium catalysts.

[0064] While the present invention has been particularly shown and described with reference to certain specific embodiments, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the scope of the invention as defined by the appended claims.

Claims

1. 1. A method for recycling a supported palladium catalyst or a supported platinum catalyst comprising palladium or platinum and a base metal disposed on a ceramic support, the method comprising: leaching the palladium or platinum and the base metal from the ceramic support using a hydrochloric acid leachate to produce a hydrochloric acid leachate containing the palladium or platinum and the base metal; passing the leachate through a column containing a material that selectively adsorbs the palladium or the platinum; eluting the palladium or platinum from the column using an eluent to produce a solution containing the palladium or platinum; treating a solution containing the palladium or the platinum to recover the palladium or the platinum; A method comprising:

2. 2. The method of claim 1, wherein the base metal comprises one or more transition metals and / or one or more post-transition metals, optionally one or both of tin and molybdenum.

3. The method of claim 1 or claim 2, wherein the ceramic support is a metal oxide material, a metal nitride material, or a metal carbide material.

4. The method of any one of claims 1 to 3, wherein the ceramic support comprises zirconia.

5. The method according to any one of claims 1 to 4, wherein the ceramic support is not subjected to a pyrolysis or chemical decomposition process.

6. The method according to any one of claims 1 to 5, wherein after the palladium or platinum and the base metal are leached from the ceramic support, the ceramic support is recovered and reused.

7. 7. The method of any one of claims 1 to 6, wherein the hydrochloric acid leachate has a hydrochloric acid concentration of at least 1 M, 2 M, or 3 M and not more than 8 M, not more than 7.5 M, or not more than 7 M, or a hydrochloric acid concentration within a range defined by any combination of said lower and upper limits.

8. The method of any one of claims 1 to 7, wherein the hydrochloric acid leachate further comprises an oxidizing agent.

9. 9. The method of claim 8, wherein the oxidizing agent is hydrogen peroxide or chloric acid.

10. 10. The method of any one of claims 1 to 9, wherein the leaching step is carried out at a temperature of at least 20°C, 30°C, or 40°C, but not more than 95°C, not more than 80°C, or not more than 70°C, or at a temperature within a range defined by any combination of the lower and upper limits.

11. The method of any one of claims 1 to 10, wherein the supported palladium catalyst or the supported platinum catalyst is crushed or milled before leaching.

12. The method of any one of claims 1 to 11, wherein the material in the column comprises a polymer resin.

13. The method of claim 12 , wherein the polymeric resin comprises an ion exchange resin or a molecular recognition resin.

14. The supported catalyst is a supported palladium catalyst, and the eluate is (NH ４ ) ２ SO ３ or NH ４ HSO ３ The method according to any one of claims 1 to 13, comprising:

15. After the palladium is eluted, the solution containing palladium is treated with HCl and H ２ O ２ Pd(NH ３ ) ２ Cl ２ 15. The method of claim 14, wherein the palladium that precipitates as a salt is recovered.

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