KR20230097378A - Method for recovering high purity platinum from a waste catalyst for fuel cells - Google Patents

Abstract

The present invention relates to a method for recovering platinum from a spent catalyst generated during the process of manufacturing a platinum catalyst for a fuel cell. In the present invention, as an embodiment, the first step of putting the spent catalyst in a crucible made of quartz and heating it at a temperature of 180 ° C to 220 ° C for 5 hours or more and the spent catalyst after performing the first step are heated in the crucible at 830 ° C to 870 ° C A method for recovering high-purity platinum from a spent catalyst for a fuel cell including a second step of heating at a temperature of 6 hours or more is proposed.

Description

Method for recovering high purity platinum from a waste catalyst for fuel cells}

The present invention relates to a method for recovering platinum, a precious metal, in high purity from a spent catalyst generated during the production of a platinum catalyst for a fuel cell.

Polymer electrolyte fuel cells are being developed in various fields with advantages such as excellent energy conversion efficiency and high current density that can be obtained even at low temperatures. The performance of the fuel cell is highly dependent on the characteristics of the membrane-electrode assembly, and in order to secure a wide reaction area even at low temperatures, the catalyst is manufactured by forming fine platinum particles on the support with a high amount of support.

In the process of preparing a catalyst for a fuel cell, if the size of the catalyst, the content of platinum, and the degree of dispersion of the catalyst do not satisfy the required conditions, it is difficult to use it as a waste catalyst. In this way, it is necessary to appropriately recover platinum, which is a valuable metal and a limited resource, from waste catalyst generated during the process of producing catalysts for fuel cells.

Methods for recovering platinum from conventional waste catalysts are largely divided into wet methods and dry methods. Of these, the dry method uses a smelter and is more suitable than the wet method for separating and recovering platinum from waste catalyst for fuel cells using carbon as a carrier.

At this time, in the case of the dry method using an incinerator, impurities generated due to corrosion of the incinerator itself may contaminate the separated platinum and reduce its purity. Therefore, it needs improvement.

Republic of Korea Patent Publication No. 10-2021-0098577 (2021.08.11) Republic of Korea Patent Registration No. 10-1452809 (2014.10.14)

The main object of the present invention is to solve the problems of the prior art. The method for recovering platinum using an incinerator according to the prior art has a problem in that impurities generated due to corrosion of the incinerator itself contaminate the separated platinum to reduce purity.

Other detailed objects of the present invention will be clearly identified and understood by experts or researchers in the art through the specific contents described below.

In order to solve the above problems, the present invention, as an embodiment, is a method of recovering platinum from a waste catalyst generated during the process of manufacturing a platinum catalyst for a fuel cell. Recovering high-purity platinum from the spent catalyst for a fuel cell, which includes a first step of heating for 5 hours or more and a second step of heating the spent catalyst after performing the first step in the crucible at a temperature of 830° C. to 870° C. for 6 hours or more. Suggest how to do it.

As an additional step, after the second step, a third step of removing residual carbon by introducing compressed air at a rate of 0.5 to 1 liter per minute while maintaining the temperature of the crucible at 450 ° C to 550 ° C is further performed. can

According to an embodiment of the present invention, high-purity platinum can be obtained from waste catalyst generated during the process of manufacturing a platinum catalyst for a fuel cell.

Other effects of the present invention will be clearly identified and understood by experts or researchers in the art through the specific details described below or during the course of practicing the present invention.

1 is a view showing a schematic structure of a combustion furnace according to an embodiment of the present invention.
FIG. 2 is a flow chart of a method for recovering high-purity platinum from a spent catalyst for a fuel cell according to the embodiment shown in FIG. 1;

Since the present invention can make various changes and have various embodiments, specific embodiments will be exemplified and described in detail.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention.

Singular expressions include plural expressions unless the context clearly indicates otherwise. The terminology in this application is intended to designate that the features, numbers, elements, or combinations thereof described in the specification exist, but the presence or possibility of addition of one or more other features, numbers, elements, or combinations thereof is determined in advance. It should be understood that it is not excluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as consistent with meanings in the context of the related art, and unless explicitly defined in this application, they are not interpreted in an ideal or excessively formal meaning.

Hereinafter, a method for recovering high-purity platinum from a spent catalyst for a fuel cell according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 schematically shows a combustion furnace to which a method of recovering high-purity platinum from a spent catalyst for a fuel cell according to an embodiment of the present invention is applied.

The combustion furnace 100 includes a housing 10 in which a container-type crucible 30 with an open top is mounted, and an upper structure 20 coupled to the housing 10 to form a cover.

The housing 10 is provided with a recessed groove shape where the crucible is detachably mounted, and a heating means 11 for heating the crucible is provided on the inner circumferential surface of the groove. Here, the heating means 11 may be one of various known means capable of heating the crucible to a high temperature, and may be, for example, a heater wire heated by receiving power. Further, the housing is provided with a flame retardant insulating sheet, a thermal sensor, etc. to block heat loss to the outside.

The upper structure 20 is provided with an exhaust pipe 21 vertically connected to the upper part of the crucible and discharging gas generated as the crucible is heated to an external purification device.

In addition, the upper structure 20 is connected to a separate compressed air supply means (not shown), so that the air supplied by the compressed air supply means is introduced into the upper part of the crucible. Here, the compressed air supply means may be configured to directly compress and provide atmospheric air with a compressor, or to provide the corresponding gas through a gas storage tank and a regulator.

In addition, the compressed air supply means may include a means for removing moisture from the gas to be provided, a means for raising the temperature to a high temperature, and a means for precisely adjusting the flow rate of the provided air. Means for improving air quality in this way may be the same as those already known.

The upper structure 20 is provided with a pipe 22 forming a flow path through which the high-pressure gas provided from the compressed air supply means is directly or indirectly exposed to the waste metal inside the crucible, and an outlet or nozzle is provided at the end of the pipe 22 are provided As a result, the compressed gas supplied from the pipe 22 quickly releases the light substance and discharges it to the exhaust communication 21.

The material of the crucible 30 is quartz. In particular, a quartz glass crucible manufactured by forming a SiO ₂ particle layer on the inner wall of a porous metal mold for which a vacuum-assisted forming method can be used and sintering the SiO 2 particle layer may be used.

The waste catalyst to which the embodiment of the present invention is applied is a platinum catalyst for a fuel cell in which carbon is used as a support and platinum is supported on the carbon. The object to be recovered from the waste catalyst is expensive platinum, and carbon used as a support is treated as an impurity.

A method for recovering high-purity platinum from a spent fuel cell catalyst according to an embodiment of the present invention includes the steps of a) removing moisture by placing the spent catalyst in a quartz crucible and heating it, and b) heating the dried waste catalyst to a high temperature. and separating and removing the carbon. During the process of heating the spent catalyst to a high temperature, since impurities are not introduced into the quartz crucible, the remaining platinum purity can be increased.

Furthermore, after the carbon is first removed, step c) of blowing high-pressure gas at a relatively low temperature to more reliably remove the residual carbon may be further performed. Step c) is an additional process and may be omitted according to embodiments.

a) In the step of drying the spent catalyst, the crucible is heated at a temperature of 180 ° C to 220 ° C for 5 hours or more. As the spent catalyst is heated for a sufficient time (around 5 hours), remaining moisture and volatile substances are removed.

b) The temperature of the crucible is raised to a temperature of 830 ° C to 870 ° C, and the spent catalyst is heated for 6 hours or more. This removes carbon and leaves platinum remaining. The heating time may vary depending on the amount of the spent catalyst, and is preferably 6 to 8 hours depending on the time for which carbon is expected to be sufficiently removed, and heating may be longer.

On the other hand, in step c), which is additionally performed after removing carbon by heating, while maintaining the temperature of the crucible at 450 ° C to 550 ° C, the gas provided from the compressed air supply means is injected into the combustion furnace at a rate of 0.5 liter to 1 liter per minute. As the gas supplied from the compressed air supply unit, general compressed air having a pressure of 1.1 to 1.3 atm may be used.

The gas injected into the combustion furnace is supplied to the spent catalyst contained in the crucible and circulated so that remaining carbon and other light foreign substances can be discharged and removed.

Next, an embodiment of a method for recovering high-purity platinum from a spent catalyst for a fuel cell according to an embodiment of the present invention will be described in detail. The following examples are merely illustrative of one form of the present invention, and the scope of the present invention is not limited by the following examples.

[Example 1]

300 g of waste fuel cell catalyst (platinum/carbon) generated during the manufacture of fuel cell catalysts was weighed and placed in a 5L quartz crucible. Thereafter, the crucible was put into a furnace and heated at a temperature of 200° C. for 2 hours to remove moisture. After the moisture was removed, the temperature was raised to 850° C., heated for 6 hours to remove carbon, and then allowed to cool to room temperature. The sample was then weighed and analyzed.

[Example 2]

300 g of waste fuel cell catalyst (platinum/carbon) generated during the manufacture of fuel cell catalysts was weighed and transferred to a 5 L quartz crucible. Thereafter, the crucible was put into a furnace and heated at a temperature of 200° C. for 2 hours to remove moisture. After the moisture was removed, the temperature was raised to 850° C. and the carbon was first removed by heating for 6 hours. Thereafter, the temperature was cooled to 500° C., and the remaining carbon was secondarily removed by injecting high-pressure gas at a flow rate of 1 L/min for 1 hour, followed by cooling to room temperature. The sample was then weighed and analyzed.

[Comparative Example 1]

300 g of spent fuel cell catalyst (platinum/carbon) generated during the manufacture of fuel cell catalysts was weighed and transferred to a 5 L metal crucible for incineration. Thereafter, the crucible was put into a furnace, heated at a temperature of 500° C. for 5 hours, and then cooled to room temperature. The sample was then weighed and analyzed.

[Comparative Example 2]

As a conventional method for recovering platinum, 450 g of silica sand, 1050 g of calcium carbonate, 350 g of iron oxide, and 350 g of copper oxide, along with 300 g of waste fuel cell catalyst (platinum/carbon) generated during the manufacture of fuel cell catalysts, are weighed and put into a mixer at 150 RPM. After mixing, it was transferred to a carbon crucible. Thereafter, the crucible was put into a high-frequency melting furnace and heated at a temperature of 1350° C. for 0.5 hour. Thereafter, the slag component at the top was removed, and oxygen was added at a level of 2 L/mim for 2 hours to remove impurities, and then the mixture was cooled to room temperature. The samples were then weighed and analyzed.

The results of analyzing the components of Examples 1 to 3 and Comparative Examples 1 and 2 above are shown in Table 1 below.

element raw material Example 1 Example 2 Comparative Example 1 Comparative Example 2 B 0 0 0 3 80 Ca 0 0 0 0 28000 Cr 86 86 86 424 40 Cu 0 0 0 0 280000 Fe 150 200 200 5000 350000 K 35 50 50 40 50 Na 15 20 20 18 0 Ni 88 120 120 0 0 Si 50 60 60 55 0 Impurity Total
(ppm) 424 536 536 5540 658170 Insoluble residue in sample (%) 40 1.5 0.5 8 0 Raw material amount (g) 300 300 300 300 300 Weight after pretreatment (g) - 184.5 181.5 204 650.5 Sample loss rate (%) - 38.5 39.5 32 -116.8

Al, Bi, Cd, Co, Mg, Mn, Sn, and Zn not shown in Table 1 above were not detected. In Examples 1 and 2, it was possible to recover high-purity platinum (99.9%) with an impurity content of 1000 ppm or less.

It is obvious that the specific description of the present invention described above is likely to be variously practiced by those skilled in the art.

Such modified embodiments should not be individually understood from the technical spirit or perspective of the present invention, and thus modified embodiments will be said to fall within the scope of the claims of the present invention.

Although the detailed description of the present invention described above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those having ordinary knowledge in the art will find the spirit of the present invention described in the claims to be described later. And it will be understood that the present invention can be variously modified and changed without departing from the technical scope.

100: furnace
10: housing 11: heating means
20: superstructure 21: exhaust communication 22: piping
30 : crucible

Claims (2)

A method of recovering platinum from waste catalyst generated during the process of manufacturing a platinum catalyst for a fuel cell,
A first step of putting the spent catalyst in a quartz crucible and heating it at a temperature of 180 ° C to 220 ° C for 5 hours or more; and
A second step of heating the spent catalyst after performing the first step in the crucible at a temperature of 830 ° C to 870 ° C for 6 hours or more
A method for recovering high-purity platinum from spent catalysts for fuel cells.
In paragraph 1,
After going through the second step
While maintaining the temperature of the crucible at 450 ° C. to 550 ° C., a third step of removing residual carbon by introducing compressed air at 0.5 liter to 1 liter per minute is further performed.
A method for recovering high-purity platinum from spent catalysts for fuel cells.

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