KR101226946B1 - Method for recycling platinum from platinum based catalysts - Google Patents

Abstract

The present invention relates to a method for recovering platinum from a platinum-based catalyst, and more particularly, to prepare a platinum chloride solution by adding aqua regia to a platinum-based spent catalyst, and then adding acetone together with triphenylphosphine to form tetrakis. It relates to a method for recovering platinum by precipitating (triphenylphosphine) platinum (Tetrakis (triphenylphosphine) platinum). Platinum recovery method of the present invention has no chlorine gas discharge as compared to the conventional method for recovering platinum by firing ammonium chloroplatinic acid, it is possible to recover the platinum at a calcination temperature of 380 ~ 500 ℃ mild conditions. In addition, the recovered platinum can be applied again to the production of platinum-based catalysts, etc., and thus it is possible to cope with the increasing demand for platinum.

Description

Platinum recovery method from platinum-based catalyst {METHOD FOR RECYCLING PLATINUM FROM PLATINUM BASED CATALYSTS}

The present invention relates to a method for recovering platinum, which is an effective resource, from a platinum-based spent catalyst.

Catalysts are used to control the reaction rate (Reaction Rate Control) in a variety of processes, the faster reaction rate is called a forward catalyst, the slower reaction rate is called a subcatalyst. Catalysts are mainly used in the production of products by chemical companies, petroleum refining companies, food companies, and pharmaceutical companies. Spent catalysts are called waste catalysts because their function is lost after use.

In general, platinum group metals (PGMs) are used as raw materials for catalysts due to their excellent physical and chemical properties, and their demand is rapidly increasing as the industry develops. In particular, as the fuel cell that converts chemical energy generated by oxidation of fuel into direct electric energy has been spotlighted as the next generation energy source, research in the automobile industry is actively conducted, and the demand for platinum for fuel cell electrode catalysts is expected to increase significantly. have. However, since platinum group metals are expensive and have limited reserves, interest in recycling platinum group metals is increasing.

Developed countries have already developed technologies to commercially extract and recover precious metals such as Pt, Pd, and Rh from spent catalysts, but Korea does not have the technology to extract and recover these platinum group metals. There is a vicious cycle of exporting used waste catalyst to Japan and other places at low prices and importing expensive high-purity platinum groups.

The techniques for recovering platinum group metals from spent catalysts are roughly classified into dry and wet methods, which are known to be suitable for large-capacity treatments of 100 tons / month and wet methods to treat waste catalysts of about 30 tons / month. In developed countries such as Japan and the United Kingdom, waste catalysts are processed in large quantities by a dry method using a smelter that is suitable for large-capacity processing of 100 tons / month or more. However, in the dry method, the initial investment costs such as the construction of large furnaces are excessive, there is a problem of generating bulky slag and loss of precious metals, and air pollution cannot be ignored. On the other hand, the wet method is advantageous in that the process installation cost is low, no slag is generated, and carbon, alumina, silica, etc., which are the main components of the carrier, can be recovered.

As one of the wet methods, aqua regia is added to platinum scrap, heated and decomposed to prepare a chloroplatinic acid solution, and platinum is recovered from this. In Republic of Korea Patent No. 10-0209124, Republic of Korea Patent Publication No. 10-2007-0089978 and the like to add aqua regia to the platinum-based catalyst to make a chloroplatinic acid solution, to which ammonium chloride (ammonium chloride) is added to ammonium chloride A method of recovering platinum by forming a precipitate of hexachloroplatinate) and then filtering and calcining the precipitate is disclosed. However, in this case, the firing temperature is 700 ~ 800 ℃ or more, there is a problem that chlorine gas (Cl ₂ ) that affects the equipment is toxic and corrosive to the human body is generated.

Accordingly, the present inventors tried to solve the above problems, and after adding aqua regia to the platinum-based waste catalyst to prepare a chloroplatinic acid solution, by adding triphenylphosphine (triphenylphosphine) platinum (triphenylphosphine) platinum ( When acetone is added to precipitate Tetrakis (triphenylphosphine) platinum), the properties of acetone that are well soluble in water and well mixed with organic solvents cause the mixture of chloroplatin chloride solution and triphenylphosphine dissolved in organic solvent chloroform to mix well. The precipitation activity of triphenylphosphine) platinum can be increased, and then, by firing tetrakis (triphenylphosphine) platinum to remove triphenylphosphine, without generating toxic gas such as chlorine gas, It has been found that high purity platinum can be recovered at low firing temperatures to complete the present invention.

That is, an object of the present invention is to provide a method for recovering platinum under mild reaction conditions without toxic gas emissions from the platinum-based spent catalyst.

The present invention

Adding aqua regia to the platinum-based catalyst to prepare a chloroplatinic acid solution;

Filtering the chloroplatinic acid solution to separate insoluble solid components;

Adding acetone and triphenylphosphine to the filtrate obtained by the filtration to precipitate tetrakis (triphenylphosphine) platinum; And

Recovering platinum by calcining the tetrakis (triphenylphosphine) platinum precipitate;

Characterized in that the method for recovering platinum from a platinum-based catalyst comprising a.

According to the method for recovering platinum from the platinum-based catalyst according to the present invention, the precipitation activity can be increased by adding acetone in the step of precipitating tetrakis (triphenylphosphine) platinum. In addition, there is no emission of chlorine gas, which improves the working environment, prevents the problem of equipment corrosion, and reduces the energy consumption because platinum can be recovered under mild reaction conditions with a relatively low firing temperature. In particular, by recovering high-purity platinum, which is an expensive rare metal, from the platinum-containing catalyst that has been discarded or exported at a low value, it is expected to be able to respond to the fuel cell electrode catalyst field in which the demand for platinum is rapidly increasing.

1 is a diagram illustrating a method for recovering platinum from the platinum catalyst of the present invention.
FIG. 2 shows the amount of platinum dissolved according to temperature and time of aqua regia when 10 mL of aqua remnant is added to 500 mg of Pt / C catalyst (19.7 wt% of Pt loading).

Hereinafter, the present invention will be described in more detail.

In the present invention, after adding aqua regia to the platinum-based waste catalyst to prepare a chloroplatinic acid solution, triphenylphosphine (triphenylphosphine) is added to precipitate tetrakis (triphenylphosphine) platinum, and this It relates to a method of recovering platinum by firing.

In the step of preparing a chloroplatinic acid solution by adding aqua regia to the platinum-based catalyst, if the platinum-based catalyst is a catalyst containing platinum, the type is not particularly limited, and a catalyst in which platinum is supported on carbon, alumina, silica, etc. may also be used. have. The aqua regia is a mixture of nitric acid (HNO ₃ ) 1 volume ratio and hydrochloric acid (HCl) 3 volume ratio, by adding aqua regia, the platinum in the catalyst is dissolved in the chloroplatinic acid to prepare a chloroplatinic acid solution. It is preferable that the temperature of aqua regia is 75-90 degreeC. If the temperature of the aqua regia is lower than 75 ° C, platinum contained in the catalyst may not remain completely dissolved as chloroplatinic acid, and thus may have a problem in that the recovery rate of platinum is lowered. It is preferable to select a temperature in the above range. Figure 2 shows the dissolved amount of platinum with the temperature and time of aqua regia when 10 mL of aqua remnant is added to 500 mg of Pt / C catalyst (Pt loading amount 19.7% by weight), stirring at room temperature for 25 hours, Or the ultrasonic dispersion shows that the platinum does not melt completely. In addition, the amount of aqua regia is preferably 10 to 15 mL based on 500 mg of catalyst. If the amount of aqua remnants is too small, platinum may not be sufficiently dissolved. On the contrary, when the amount of aqua regia is too large, tetrakis (triphenylphosphine) is used. Since there may be a problem that the speed is slow when forming the platinum precipitate, it is better to select the above range.

In the step of filtering the chloroplatinic acid solution to separate the insoluble solid component, the insoluble solid component is a carrier, such as carbon, alumina, silica, and other impurities that are not dissolved by aqua regia, and is separated by filtration. It is preferable to use a membrane filter for filtration. To recover the chloroplatinic acid solution absorbed in the carrier and impurities, it is preferable to perform filtration while sufficiently washing the carrier and impurities with an organic solvent such as acetone or ethyl alcohol. Do. The chloroplatinic acid solution recovered by filtration is preferably subjected to a process of evaporating the organic solvent introduced in the washing process, in order to match the correct ratio of acetone added to the chloroplatinic acid solution.

In the step of precipitating tetrakis (triphenylphosphine) platinum by adding acetone and triphenylphosphine to the filtrate obtained by the filtration, the acetone increases the precipitation activity of tetrakis (triphenylphosphine) platinum to recover platinum. Add to improve Acetone is well soluble in water and well mixed with organic solvents, so when added, triphenylphosphine dissolved in chloroplatinic acid solution and organic solvent chloroform is mixed well to improve the precipitation activity of tetrakis (triphenylphosphine) platinum. Can be. At this time, the volume ratio of the filtrate and acetone is preferably 1: 0.1 to 1.0, preferably 1: 0.3 to 0.5. If the amount of acetone is added below 0.1, the increase in precipitation activity is not sufficient. If so, due to the dilution effect, there may be a problem that the precipitation activity falls again. In addition, the triphenyl phosphine reacts with chloroplatinic acid in 4: 1 equivalent to precipitate yellow tetrakis (triphenylphosphine) platinum. Triphenylphosphine is a crystalline material, preferably dissolved in a solvent to accelerate the formation of tetrakis (triphenylphosphine) platinum. Although triphenylphosphine is insoluble in water, it is known to dissolve in organic solvents such as chloroform, benzene, ether, carbon tetrachloride, acetic acid, etc. Of these, it is preferable to select chloroform as a solvent because it dissolves quickly in chloroform.

When tetrakis (triphenylphosphine) platinum precipitates, it is filtered through a membrane filter and recovered by drying. When performing the filtration process using a membrane filter, the filtration process is performed while washing with an organic solvent, for example, alcohol such as methyl alcohol or ethyl alcohol, to increase the purity of tetrakis (triphenylphosphine) platinum. Preferably, washing is carried out until the filtrate becomes colorless and transparent. The tetrakis (triphenylphosphine) platinum recovered through the drying process is then calcined to recover platinum. The firing temperature is preferably 380 ~ 500 ℃, if the temperature is less than 380 ℃ lower than the boiling point of the triphenyl phosphine may be a problem that can not be removed, on the contrary, if it exceeds 500 ℃ of the tetrakis (triphenyl phosphine) platinum There may be a problem that the loss of platinum caused by volatilization.

In the method for recovering platinum from the platinum-based catalyst according to the present invention, there is no generation of harmful gases, such as chlorine gas, compared to the process of calcining ammonium chloroplatinic acid. In terms of advantages. In addition, by adding triphenylphosphine to the chloroplatinic acid solution to precipitate the tetrakis (triphenylphosphine) platinum, by adding acetone, the precipitation activity can be increased to increase the platinum recovery rate.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

[Example]

Example 1

500 mg of Pt / C catalyst (Pt loading amount 19.7% by weight) was placed in a 50 mL beaker, 10 mL of aqua regia was added, and then maintained at 80 ° C. for 1 hour to prepare a chloroplatinic acid solution in which the supported platinum was completely dissolved. After cooling the chloroplatinic acid solution to room temperature and filtering it using a membrane filter, the filtered insoluble carbon carrier was again filtered with washing with acetone to separate the carrier. The chloroplatinic acid solution as a filtrate was left at room temperature for 3 hours to evaporate all acetone introduced during washing. After all the acetone has been evaporated, aqua regia is added to the chloroplatinic acid solution to replenish the evaporated aqua regia. The total volume of the chloroplatinic acid solution is adjusted to 10 mL, and 1 mL of acetone is added, followed by chloroform in which triphenylphosphine is dissolved. 1 mL of solution (concentration 2M) was added to precipitate tetrakis (triphenylphosphine) platinum. Subsequently, the precipitated tetrakis (triphenylphosphine) platinum is filtered through a membrane filter, and the filtered tetrakis (triphenylphosphine) platinum is filtered again while washing with ethyl alcohol until the filtrate becomes colorless and transparent. 1 hour drying in 80 ℃ oven to recover the tetrakis (triphenylphosphine) platinum. Thereafter, tetrakis (triphenylphosphine) platinum was calcined at 400 ° C. for 3 hours in a furnace to recover platinum.

Examples 2 to 5

In the same manner as in Example 1, but adjust the total volume of the chloroplatinic acid solution to 10 mL, acetone 2 mL (Example 2), 4 mL (Example 3), 6 mL (Example 4), 8 mL (Example 5) was added.

Comparative example

In the same manner as in Example 1, the total volume of the chloroplatinic acid solution was adjusted to 10 mL, and then tetrakis (triphenylphosphine) platinum was added by adding only a chloroform solution in which triphenylphosphine was dissolved without adding acetone. Precipitated.

division Acetone addition amount (mL) Recovered platinum (mg) Recovery rate (%) Example 1 One 61.3 62.2 Example 2 2 73.7 74.8 Example 3 4 95.6 97.1 Example 4 6 80.5 81.7 Example 5 8 73.0 74.1 Comparative example 0 49.9 50.7

Table 1 shows the mass and recovery of platinum recovered in Examples 1 to 5 and Comparative Examples. As can be seen in Table 1, when acetone is not added, the recovery rate is the lowest as 50.7%, and the recovery rate increases as the acetone is added little by little, and when the volume ratio of chloroplatinic acid solution and acetone is 1: 0.4, the recovery of platinum is 97.1. Highest in%. This is because the addition of acetone increases the precipitation activity of the tetrakis (triphenylphosphine) platinum and increases the mass of the precipitate used for firing. However, when the amount of acetone added exceeds 0.4 and the volume ratio is increased to 0.6 and 0.8 by volume, the dilution effect causes the precipitation activity and the recovery rate of tetrakis (triphenylphosphine) platinum to fall again. Did not do it. In addition, 10 mg of the recovered platinum was dissolved in 3 mL of aqua regia. As a result of ICP analysis, it was confirmed that the purity was 100% at 3341 ppm.

As a result, according to the platinum recovery method of the present invention, it was confirmed that high purity platinum can be recovered from the platinum-based waste catalyst in a simple and economical manner without the release of toxic gases under mild reaction conditions.

Claims (4)

Adding aqua regia to the platinum-based catalyst to prepare a chloroplatinic acid solution;
Filtering the chloroplatinic acid solution to separate insoluble solid components;
Adding acetone and triphenylphosphine to the filtrate obtained by the filtration to precipitate tetrakis (triphenylphosphine) platinum; And
Recovering platinum by calcining the tetrakis (triphenylphosphine) platinum precipitate;
Platinum recovery method from a platinum-based catalyst comprising a.
The method of claim 1, wherein the temperature of the aqua regia is 75 to 90 ℃.
The method for recovering platinum from a platinum-based catalyst according to claim 1, wherein the volume ratio of the filtrate obtained by filtration and the acetone is 1: 0.1 to 1.0.
The method for recovering platinum from a platinum-based catalyst according to claim 1, wherein the calcination is performed at 380 to 500 ° C.

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