Recycling components of supported palladium and platinum catalysts

Abstract

A method of recycling a supported palladium or platinum catalyst, the supported palladium or 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 to produce a hydrochloric acid leach comprising the palladium or platinum and the base metal; passing the leachate through a column comprising a material that selectively adsorbs the palladium or platinum; eluting the palladium or platinum from the column using an eluent to produce a solution comprising the palladium or platinum; and treating the solution comprising the palladium or platinum to recover the palladium or platinum.

Description

Technical Field

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

[0002] It is well known that catalysts containing one or more platinum group metals (PGMs) can be used in a wide range of applications. One or more PGMs can also be combined with one or more base metals to provide a mixed metal catalyst. In addition, PGM catalysts can be provided on a support material, such as a ceramic support material, to provide a supported catalyst material.

[0003] Palladium catalysts and platinum catalysts are particularly suitable for certain applications. As generally described above for PGM catalysts, such catalysts can contain palladium or platinum combined with one or more base metals (or non-PGMs), and such catalysts can be provided on a support material such as a ceramic support.

[0004] As the demand for PGMs increases, the demand for recycling and reusing these materials also increases. In addition, there is an increasing need to recycle PGMs in a more energy-efficient, economical, sustainable, and environmentally friendly manner. In addition, there is a need to recycle PGMs from multi-component materials in a way that can also recycle one or more other components, such as the support material of the supported PGM catalyst.

[0005] Regarding the above, the recovery of platinum group metals (PGMs) from supported catalyst materials is typically achieved by smelting. This involves heat-treating the supported PGM material, which can be energy-consuming, costly, and can cause environmental damage and pollution. For mixed metal catalysts, such smelting processes may produce a mixed metal alloy that requires significant further processing to extract and purify the PGM component. In addition, such smelting processes may also damage the support material, making it unsuitable for reuse.

[0006] The aim of this specification is to solve these problems. Summary of the Invention

[0007] This specification provides a method for recycling a supported palladium catalyst or a platinum catalyst, the supported palladium catalyst or platinum catalyst comprising palladium or platinum and a base metal disposed on a ceramic support, the method comprising:

[0008] leaching palladium or platinum and the base metal from the ceramic support using a hydrochloric acid leaching solution to produce a hydrochloric acid leaching solution containing the palladium or platinum and the base metal;

[0009] passing the leaching solution through a column containing a material that selectively adsorbs palladium or platinum;

[0010] eluting palladium or platinum from the column using an eluent to produce a solution containing palladium or platinum; and

[0011] Treating a solution containing palladium or platinum to recover palladium or platinum.

[0012] This method recovers palladium or platinum through a hydrometallurgical route, where the ceramic support can be reused. Compared with smelting, it provides a more sustainable recycling route because the supported palladium catalyst / platinum catalyst does not require heat treatment. The ceramic support can be a metal oxide, metal nitride, or metal carbide material. An advantage of an example of the method of the present invention is that the ceramic support is not subjected to heat or chemical decomposition treatment. Thus, after leaching palladium or platinum and base metals from the ceramic support, the ceramic support can be recovered and reused.

[0013] The base metals can include more than one type of base metal. For example, the base metals can include one or more transition metals and / or one or more post-transition metals or consist of them. Examples include one or both of tin and molybdenum. The ceramic support can include zirconia or consist of zirconia. It has been found that using a hydrochloric acid leaching solution can leach palladium / platinum and base metals (such as tin and molybdenum) from a ceramic support (such as zirconia) to produce a hydrochloric acid leaching solution containing palladium / platinum and base metals. In addition, the ceramic support can be recovered and reused.

[0014] It has also been found that commercially available ion exchange materials / molecular recognition materials in a column can be used to selectively adsorb palladium / platinum from the leaching solution, while the base metals pass through the column. Then, palladium / platinum can be eluted from the column and recovered, for example, by precipitation in the form of palladium salts / platinum salts. Thus, this method is capable of recovering palladium / platinum and the ceramic support (and optionally base metals) using a hydrometallurgical route, avoiding smelting and treatments that damage the support material.

[0015] The hydrochloric acid leaching solution can have the following hydrochloric acid concentrations: at least 1 M, 2 M, or 3 M; not exceeding 8 M, 7.5 M, or 7 M; or within a range defined by any combination of the above lower and upper limits. The hydrochloric acid leaching solution can also contain an oxidant, such as hydrogen peroxide or chlorate. The leaching step can be carried out at the following temperatures: at least 20 °C, 30 °C, or 40 °C; not exceeding 95 °C, 80 °C, or 70 °C; or within a range defined by any combination of the above lower and upper limits. In addition, the supported palladium catalyst / platinum catalyst can be ground or milled before leaching. Grinding or milling the supported palladium catalyst / platinum catalyst can reduce the need for an oxidant. It should be noted that although grinding or milling may reduce the particle size of the ceramic support material, the material does not thermally degrade or chemically degrade and can still be recycled.

[0016] The column for selectively adsorbing palladium / platinum from the leaching solution can contain a polymeric ion exchange resin / molecular recognition resin, such as commercially available SuperLig TM resin (e.g., SuperLig for selective Pd extraction TM2 resin). The palladium / platinum can then be recovered from the column. For example, palladium can be recovered by elution using (NH4)2SO3 or NH4HSO3, and subsequently the eluted solution is treated with, for example, HCl and H2O2 to precipitate in the form of Pd(NH3)2Cl2 salt.

[0017] After leaching palladium / platinum and base metals from the ceramic support, the ceramic support can be recovered and reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a better understanding of the present invention and to show how it may be practiced, certain embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0019] Figure 1 A graph showing the relationship of the leached metal % with respect to the molar concentration of the acid for palladium, tin, and molybdenum;

[0020] Figure 2 A graph showing the relationship of the leached metal mass with respect to the volume of the oxidizing agent added for palladium, tin, and molybdenum;

[0021] Figure 3 A graph showing the relationship of the leached metal % with respect to the volume of the oxidizing agent added for palladium, tin, and molybdenum;

[0022] Figure 4 Showing the supported catalyst before leaching (palladium, tin, and molybdenum on zirconia);

[0023] Figure 5 Showing after leaching Figure 4 of the catalyst;

[0024] Figure 6 A graph showing the relationship of the leached metal concentration with respect to time during initial leaching with only HCl and then leaching with HCl and sodium chlorate;

[0025] Figure 7 A graph showing the relationship of the leached metal % with respect to time during initial leaching with only HCl and then leaching with HCl and sodium chlorate; and

[0026] Figure 8 A graph showing the relationship of the leached metal % with respect to the volume of H2O2 added. DETAILED DESCRIPTION

[0027] As described in the Summary of the Invention section, this specification provides a method for recycling a supported palladium catalyst or a platinum catalyst, the supported palladium catalyst or platinum catalyst comprising palladium or platinum and base metals disposed on a ceramic support, the method comprising:

[0028] Leaching palladium or platinum and base metals from a ceramic support using a hydrochloric acid leachate to produce a hydrochloric acid leachate containing the palladium or platinum and the base metals;

[0029] Passing the leachate through a column containing a material that selectively adsorbs palladium (such as an ion exchange resin or a molecular recognition resin);

[0030] Eluting palladium or platinum from the column using an eluent to produce a solution containing the palladium or platinum; and

[0031] Processing the solution containing palladium or platinum to recover the palladium or platinum.

[0032] This method recovers palladium or platinum through a hydrometallurgical route, where the ceramic support can be reused. Compared to smelting, it provides a more sustainable recycling route because the supported palladium catalyst / 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.

[0033] This method has been exemplified with a catalyst containing Pd / Sn / Mo supported on zirconia. It has been demonstrated that Pd / Sn / Mo can be leached in HCl (0M - 8M) with or without the addition of an oxidant (such as hydrogen peroxide or chlorate). This method can be carried out at temperatures in the range of 20°C - 95°C, and the catalyst material can be processed as it is or by grinding or milling before leaching.

[0034] After leaching, the leachate can then be concentrated (e.g., by boiling down) and passed through an ion exchange / molecular recognition resin, such as SuperLig TM 2, where Pd is retained on the resin while Sn and Mo pass through the column. Then Pd can be removed from the column using, for example, ammonium sulfite. The ammonium palladium sulfite solution can then be treated with HCl and hydrogen peroxide, and Pd precipitates in the form of diamminedichloropalladium.

[0035] This method can operate in a batch process or a continuous process. The leaching of the catalyst can be carried out by filling the catalyst into a column and then circulating / recycling the acid leachate through the column.

[0036] This method enables a Pd or Pt recovery route for supported Pd (or Pt) / base metal catalysts (such as a catalyst containing Pd / Sn / Mo supported on zirconia).

[0037] Example

[0038] Example 1: Leaching of Catalyst Material (Palladium, Tin, and Molybdenum on Zirconia) at Different HCl Molar Concentrations

[0039] 40.2 g of spent catalyst (palladium, tin, and molybdenum on zirconia) was directly weighed into a 1 L flat-bottomed baffled borosilicate flanged glass reactor. 400 mL of demineralized water was added, then a top-mounted stirrer was inserted, and a five-port borosilicate glass lid was attached and clamped in place. The stirrer was connected to the top-mounted stirrer motor, and the reaction vessel was clamped in place. Three of the five ports were sealed with glass stoppers. The stirrer was immersed to a depth of approximately 3 cm from the bottom of the reactor. The experiment was conducted at room temperature. Prior to the addition of HCl, the reaction vessel contained demineralized water with the supported catalyst (palladium, tin, and molybdenum on zirconia).

[0040] The stirrer was set to 300 rpm. There was a slight visual change from clear to turbid, most likely due to the presence of fine particles within the material, and some 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 bottle.

[0041] After taking the initial sample, the first addition of 20 mL of 37% HCl was added from the graduated cylinder through one of the open ports. An immediate color change was visible - from turbid to light orange. The reaction mixture was allowed to stand for 10 minutes, then a sample was taken.

[0042] For the next 11 additions, the 20 mL HCl addition was repeated at 10-minute intervals. A 5 mL sample was taken prior to the acid addition, as described previously.

[0043] During these additions, the color gradually darkened, passing through darker orange, to brown, to brownish green, and then became very dark in the reactor, making it difficult to identify any color change.

[0044] Starting from the 13th addition, the acid volume was increased to account for a larger total volume, and the molar concentration was increased between each addition: 13th addition = 30 mL; 14th addition = 35 mL; 15th addition = 40 mL; 16th addition = 45 mL; 17th addition = 50 mL. Thus, the reaction vessel was subjected to stepwise addition of HCl prior to filtration. During the stepwise addition of HCl, a series of samples were taken from the reaction vessel for subsequent metal content analysis.

[0045] After taking the sample after the last acid addition, the stirrer motor was stopped, and the reactants were allowed to stand for approximately half an hour, then vacuum filtered through a 7 cm diameter GF / F (0.7 μm porosity) filter into a 1 L Buchner flask, which took approximately 5 minutes. The liquid was weighed, and the volume was measured prior to transfer to a 1 L bottle (net volume 711 mL, net weight 781.15 g). A sample of the finally filtered liquid was taken.

[0046] Use the same filter and Büchner flask to wash the remaining solid and rinse off any associated glassware of the liquid. Let it drain for about 5 minutes until the sample is convincingly clean and dry. The wash liquid is light orange and transparent. Weigh these and measure the volume before transferring to a 500 mL bottle (net weight 291.63 g and net volume 290 mL).

[0047] All samples were analyzed for metal content by ICP (Inductively Coupled Plasma) spectrometry. Figure 1 Plots of the leached metal % vs. the molar concentration of the acid are shown for palladium, tin, and molybdenum. It is noted that base metals (Sn and Mo) are leached together with palladium and selective leaching of palladium is not achieved. Thus, these tests indicate that palladium and base metals should be leached together and then palladium subsequently separated from the base metals for palladium recovery, e.g., by reduction to Pd metal or by precipitation in the form of Pd salts.

[0048] Example 2: HCl Leaching of Catalyst Material Using H2O2 as Oxidant

[0049] Following the previous example, the aim was to strip all or at least substantially all of the Pd, Mo, and Sn from the zirconia substrate of the spent catalyst material using 7M HCl and an oxidant (H2O2) at a maximum flow rate of 0.17 mL / min.

[0050] Weigh 35 g of the catalyst material into a 500 mL flanged container and set it on a hot plate with an overhead stirrer, condenser, and temperature probe. Add 350 mL of 7M HCl through one of the available ports using a glass funnel and set the temperature to 70 °C. Set the Gilson pump with the pump speed set to 0.5 speed (0.05 mL / min). Prime the tubing and insert it into the available port through the connector and seal with parafilm. Set the overhead stirrer to 150 rpm.

[0051] Once the 70 °C temperature is reached, start adding peroxide at the lowest rate and observe to ensure the reaction is not overly effervescent. After 5 minutes, increase the addition rate of peroxide to 0.75 (0.08 mL / min). Further increase it to 1 (0.11 mL / min) after 17 minutes, and again to 1.25 (0.14 mL / min) after 15 minutes, and finally to 1.5 (0.17 mL / min) after 30 minutes.

[0052] The reaction continued at a rate of 0.17 mL / min for 3.5 hours. Samples were taken before adding H2O2 and then hourly. Samples were taken again after cooling and a final sample was taken after filtration. The resulting liquid was filtered through a GF / F filter paper via vacuum filtration into a Büchner funnel. The residue was dried in vacuo for 10 minutes and then air-dried.

[0053] Seven samples were analyzed by ICP spectrometry. Figure 2 Plots are shown of the mass of leached metal versus the volume of added oxidant for palladium, tin, and molybdenum, while Figure 3 Plots are shown of the % of leached metal versus the volume of added oxidant for palladium, tin, and molybdenum.

[0054] Results showed that the leaching of all metals increased when using a combination of hydrogen peroxide and HCl compared to using HCl alone. Eighty percent of Pd and Sn were removed in the first 8 mL (about 1 hour), followed by an additional approximately 10% over about 3 hours or 30 mL of peroxide. If run for a longer period, the method can remove substantially all of the metals.

[0055] Example 3: HCl Leaching of Catalyst Material Using Sodium Chlorate as Oxidant

[0056] Leaching of Pd / Mo / Sn / zirconia materials with hydrochloric acid and sodium chlorate as the oxidant is described in this example.

[0057] 7 mol / L hydrochloric acid was prepared by diluting 585 mL (7 moles) of 37% w / w concentrated analytical reagent grade hydrochloric acid in a 1 L 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 .

[0058] 400 mL of 7 mol / L hydrochloric acid was measured into a 500 mL flat-bottomed baffled (x3) borosilicate glass reactor. A 5-port borosilicate glass lid was clamped in place and the reactor was positioned on top of a hot plate. A stirrer guide was attached to the middle port and through this stirrer guide, a 5 cm diameter Teflon TM coated pitched blade (downflow) impeller was immersed in the acid approximately 1 cm from the bottom of the vessel. The impeller shaft was connected to an overhead stirrer motor.

[0059] The temperature was controlled using a thermostat connected to the hot plate and through a Teflon TM probe in the solution. The volume was kept constant by using a spiral reflux condenser connected to a port on the reactor lid. A stopper was used in the free port. Teflon TM union clamps were used to prevent the ground glass adapters from loosening.

[0060] The catalyst sample (40.12 g) was slowly loaded into the acid stirred at 300 rpm and 19 °C through a glass funnel. After the addition was complete, the funnel was removed and replaced with a stopper. Some bubbles were seen during the addition, and some of the bubbles immediately dissolved, and the solution turned light orange. The temperature remained constant during the addition of the solid, and the addition was completed in less than five minutes.

[0061] Therefore, the equipment was set up for leaching metals from the supported catalyst using HCl. When heated to 95 °C (which took 45 minutes), further dissolution occurred as evidenced by the darkening of the solution color to dark orange. Samples (5 mL) were taken using a 0.45 μm syringe filter disc to remove any solids. The reaction was then allowed to continue for another 90 minutes, and samples were taken after 45 minutes and 90 minutes. There was no visible color difference between these samples.

[0062] Since there was no visible color difference in the samples taken between 45 minutes and 90 minutes, sodium chlorate was added to ensure the leaching of the remaining palladium. A narrow-bore (0.8 mm) tube 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 to remove air, the tube was installed in the connector and placed into the port on the container lid. A nitrogen gas line was added at a flow rate set to 1.0 L / min. This modified equipment was set up for leaching metals from the supported catalyst using HCl and adding sodium chlorate.

[0063] The addition of sodium chlorate was initially started at 0.5 mL / min, but this was too fast as evidenced by the production of a large amount of chlorine. After the first 5 minutes, a sample was taken and the chlorate addition was reduced to 0.25 mL / min. Additional samples were taken 55 minutes and 175 minutes after the chlorate addition. The mixture was then stirred while cooling under a nitrogen stream for approximately 1 hour until the temperature of the leachate reached 40 °C.

[0064] The leachate was vacuum filtered through a 7 cm diameter GF / F (0.7 μm porosity) filter into a 1 L Buchner flask. The leachate was then transferred to a 500 mL bottle, shaken, and sampled.

[0065] A second 1 L flask was used to collect the demineralized water washings from the reactor to aid in the transfer and washing of the solid. The total wash volume was 183 mL. The washings appeared slightly turbid. The leached catalyst was then dried and weighed (41.11 g).

[0066] Figure 4 shows the supported catalyst before leaching, while Figure 5 shows the catalyst after leaching.

[0067] Samples of the leachate were analyzed using ICP spectrometry. Figure 6Shows a graph of the metal concentration leached during initial leaching with only HCl and then leaching with HCl and sodium chlorate as a function of time. Figure 7 Shows a graph of the percentage of metal leached during initial leaching with only HCl and then leaching with HCl and sodium chlorate as a function of time.

[0068] The results show that hydrochloric acid (7M) is a suitable leaching agent for dissolving Pd from the support at 95 °C under reflux conditions. The leaching efficiencies of Pd (78%), Sn (69%) and Mo (54%) are all high and all show rapid kinetics. The ZrO2 support remains essentially insoluble throughout. The addition of sodium chlorate shows an improvement in the leachability of Pd (86%) and Sn (77%).

[0069] Example 4: HCl / H2O2 Leaching of Ground Catalyst Material

[0070] The purpose of this example is to leach all or substantially all of Pd, Mo and Sn from the zirconia substrate of the catalyst using 7M HCl and H2O2 at a maximum flow rate of 0.17 mL / min. The catalyst material is crushed before leaching.

[0071] Weigh 34 g of the spent catalyst, transfer it to a clean pestle and mortar and crush it. Once crushed, transfer the material to a 500 mL flanged container and weigh by difference. 33.21 g is used in the leaching. Add 330 mL of 7M HCl to the flanged container via one of the open ports and set the temperature to 70 °C. The other ports contain a condenser, a overhead stirrer, a line for hydrogen peroxide addition and two stoppered ports.

[0072] Set up a Gilson pump with the pump speed set to 1.25 speed (0.14 mL / min). Prime the tubing and insert it into the available port through a connector and seal with paraffin film. Set the overhead stirrer to 150 rpm. Once the temperature of 70 °C is reached, start adding peroxide and observe to ensure that the reaction does not foam too much.

[0073] After 3 minutes, the addition rate of the peroxide was increased to 1.5 (0.17 mL / min) as there was no overreaction. The reaction continued at a rate of 0.17 mL / min for 2 hours and then increased to 1.75 (0.2 mL / min). The peroxide was added for another hour at 0.2 mL / min and then increased to 2 (0.23 mL / min) in the last hour. Samples were taken before the addition of H2O2 and then hourly. Samples were taken again after cooling and a final sample was taken after filtration. All samples for analysis were filtered through a 0.45 um SFCA filter. The resulting liquid was filtered through a GF / F filter paper via vacuum filtration into a Buchner funnel. The residue was dried under vacuum for 10 minutes and then air-dried.

[0074] The samples were analyzed using ICP spectroscopy. Figure 8 A graph showing the relationship of leached metal % vs. volume of H2O2 added is presented.

[0075] Crushing the spent catalyst increased the available surface area, which allowed more metal to be leached in the acid before the addition of the peroxide, as Figure 8 shown. Additionally, crushing achieved an earlier peak in metal leaching and less peroxide was used.

[0076] Example 5: Variation of Leaching Parameters

[0077] Samples of the supported catalyst material were leached in both crushed and uncrushed forms at multiple different temperatures (20 °C, 70 °C, 95 °C). The method involved weighing 30 g of the spent catalyst into a 500 mL baffled top-flange container equipped with an overhead stirrer, a port for the addition of H2O2, a PTFE temperature probe, and two stoppered ports. Samples were taken after leaching for 1 hour without the use of an oxidant and then after another hour of leaching with hydrogen peroxide as the oxidant. Pickled and washed samples were also obtained. All samples were analyzed by ICP spectroscopy. The results are summarized in the table below.

[0078]

[0079]

[0080]

[0081] The results showed that palladium can be leached using HCl within a certain temperature range and it is not necessary to crush the catalyst material or use an oxidant, but there are some advantages to using the crushed material and oxidant as previously described. It is envisioned that the solid loading will be increased (e.g., increased to 20% or 30%) and the leachate will be reused with the un-leached spent catalyst to concentrate the leachate.

[0082] Example 6: Treatment of Leachate for Palladium Recovery

[0083] The leachate and wash liquor produced by the foregoing examples are combined and boiled down to concentrate the liquid, and then passed through a column filled with an ion exchange / molecular recognition medium to separate Pd from base metals, especially Sn.

[0084] The leachate and wash liquor were combined in a 2 L beaker and stirred for 30 minutes. Samples were taken and analyzed. Approximately half of the liquid was transferred to a 2 L round-bottom flask and placed in a distillation apparatus set at a jacket temperature of 180 °C (vapor temperature of 105 °C - 110 °C), and filled up until all the liquid was added. The liquid was boiled down until approximately 100 mL remained, and then further diluted to 160 mL with 6 M HCl.

[0085] 16.05 g of SuperLig TM 2 resin was weighed into a beaker and combined with approximately 10 mL of 6 M HCl. The resin was soaked briefly, and then transferred to a column (35 mm diameter, equipped with 2 adjustable end pieces) and the excess acid was drained off, leaving a bed height of 2.7 cm and a bed volume of 25.96 cm 3 Before passing through the column, the feed (Pd 5.5 g / L) was vacuum filtered through a 0.45 μm PVDF membrane. The feed was introduced into the column at 1.5 mL / min (Gilson minipump 3, set at 25.5) with the aim of overloading by 110%. 160 mL of the feed was passed through the column, the raffinate was collected and sampled. 6 M HCl wash liquor was passed through the column at 1.5 mL / min, and then washed with water at the same rate. These fractions were collected together and sampled.

[0086] 1 M ammonium sulfite was passed through at a rate of 0.75 mL / min to elute the Pd on the column, and the strip was collected in the form of a Pd(NH3)(SO4) solution. The column was again washed with water and 6 M HCl at a rate of 0.75 mL / min, and these fractions were collected together and sampled. Then the Pd(NH3)(SO4) solution was treated with HCl and H2O2 to precipitate the palladium in the form of the Pd(NH3)2Cl2 salt. The recovery of palladium in the form of the precipitated Pd(NH3)2Cl2 salt was thus achieved. How to use Superlig TMExamples of 2 have been published by IBC Advanced Technologies, Inc. (see, e.g., Izatt, S.R.; Bruening, R.L.; Izatt, N.E. 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, published by 2016 John Wiley & Sons, Ltd. (2016); and other publications from IBC Advanced Technologies, Inc.). Mass balance on the product found the Pd recovery to be 99.2%. Additionally, the precipitated Pd(NH3)2Cl2 salt met the market grade specifications.

[0087] While the methods of this specification have been illustrated for supported palladium catalysts, it should also be noted that the techniques described herein can also be used to recycle supported platinum catalysts using an acid leaching method and then recovering the platinum using a different ion exchange / molecular recognition resin selective for platinum. For example, publications from IBC Advanced Technologies, Inc. also disclose Superlig TM resins that are selective for platinum rather than palladium, and these resins can be used in conjunction with the acid leaching method described herein to recover platinum from ceramic supported platinum catalysts without the need for smelting. Thus, this specification is also capable of recovering platinum via a hydrometallurgical route where the ceramic support can be reused, thereby enabling a more sustainable recycling route for both ceramic supported platinum catalysts and ceramic supported palladium catalysts.

[0088] Although the present invention has been specifically shown and described with reference to certain examples, those skilled in the art should understand that various changes in form and detail may be made without departing from the scope of the present invention as defined by the appended claims.

Claims

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

2. The method according to claim 1, Wherein the base metals comprise one or more transition metals and / or one or more post-transition metals, optionally one or both of tin and molybdenum.

3. The method according to claim 1 or 2, Wherein the ceramic support is a metal oxide, a metal nitride or a metal carbide material.

4. The method according to any one of the preceding claims, Wherein the ceramic support comprises zirconia.

5. The method according to any one of the preceding claims, Wherein the ceramic support is not subjected to heat or chemical decomposition treatment.

6. The method according to any one of the preceding claims, Wherein after leaching the palladium or platinum and the base metals from the ceramic support, the ceramic support is recovered and reused.

7. The method according to any one of the preceding claims, Wherein the hydrochloric acid leaching solution has the following hydrochloric acid concentration: at least 1M, 2M or 3M; not exceeding 8M, 7.5M or 7M; or within a range defined by any combination of the above lower and upper limits.

8. The method according to any one of the preceding claims, Wherein the hydrochloric acid leaching solution further comprises an oxidant.

9. The method according to claim 8, Wherein the oxidant is hydrogen peroxide or chlorate.

10. The method according to any one of the preceding claims, Wherein the leaching step is carried out at the following temperature: at least 20°C, 30°C or 40°C; not exceeding 95°C, 80°C or 70°C; or within a range defined by any combination of the above lower and upper limits.

11. The method according to any one of the preceding claims, Wherein the supported palladium catalyst or the supported platinum catalyst is ground or milled before leaching.

12. The method according to any one of the preceding claims, Wherein the material in the column comprises a polymer resin.

13. The method according to claim 12, Wherein the polymer resin comprises an ion exchange resin or a molecular recognition resin.

14. The method according to any one of the preceding claims, Wherein the supported catalyst is a supported palladium catalyst, and the eluent comprises (NH4)2SO3 or NH4HSO3.

15. The method according to claim 14, Wherein after eluting the palladium, the solution containing the palladium is treated with HCl and H2O2 to recover the palladium precipitated in the form of Pd(NH3)2Cl2 salt.

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