JPH05212297A - Platinum group metal recovering method from metallic foil carrier catalyst - Google Patents

Abstract

PURPOSE:To provide a method for efficiently recovering a platinum group metal from a metallic foil carrier catalyst made by allowing to form a coating layer prepared by using a metallic material such as stainless steel, Fe-Cr-Al. CONSTITUTION:By treating a metallic foil carrier catalyst with as a grinding sand, an alumina coating layer carrying catalytically active component is peeled off and the alumina coating layer and the grinding sand are separated, the alumina coating layer alone is separated and recovered, and then is treated with chemicals to recover the platinum group metal.

Description

Detailed Description of the Invention

[0001]

This invention relates to stainless steel and
Using a metal material such as Fe-Cr-Al, a metal foil carrier is coated with an alumina coat layer carrying a platinum group metal, and only the alumina coat layer is recovered from the metal foil carrier catalyst. A method for recovering metal. INDUSTRIAL APPLICABILITY The present invention was developed for efficient recovery of platinum group metals from metal foil carrier catalysts such as those used to purify harmful components of exhaust gas emitted from internal combustion engines of automobiles and the like. It is a thing.

[0002]

2. Description of the Related Art As a conventional platinum group metal recovery method, there is an acid dissolution method represented by hydrochloric acid, aqua regia, etc., which is well known as a platinum group metal recovery method from a ceramic carrier catalyst. Further, an alkali dissolution method in which a metal foil carrier catalyst is leached in sodium hydroxide and a platinum group metal is recovered in a black form is also well known.

[0003]

However, since the acid dissolution method dissolves the metal foil carrier as well as the platinum group metal, in addition to requiring a large amount of chemicals, separation of the platinum group metal after dissolution, It is necessary to perform neutralization in order to efficiently separate and collect in the refining process, and as a result, the hydroxide of the metal that is the metal foil carrier raw material precipitates, leading to a decrease in efficiency and an industrially optimum method. I can't say. Further, as a problem of the alkali dissolution method, since the metal foil carrier catalyst is treated with a chemical, elution of metal from the metal foil carrier is unavoidable. There was a problem called.

[0004]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to such conventional problems, and it is possible to physically form an alumina coat layer carrying a platinum group metal without dissolving a metal foil carrier. A simple and efficient method of recovering a platinum group metal by peeling it off and treating only the alumina coat layer with a chemical is provided. The present invention will be described below.

The present invention relates to a method for recovering a platinum group metal from a metal foil carrier catalyst, wherein a catalyst having a platinum group metal carried on a metal foil carrier is treated by sandblasting with iron powder to carry the platinum group metal. This is a method of peeling only the alumina coat layer. The stripping method does not need to disassemble the metal foil carrier catalyst. All the alumina coat layers in the metal foil carrier catalyst can be peeled off by simply sandblasting one of the honeycomb structures of the metal foil carrier catalyst.

The alumina coat layer is peeled off by the iron powder and is recovered from the other side of the honeycomb structure together with the iron powder and the air. The alumina coat layer and iron powder are first separated from the air by a filter. Next, the alumina coat layer and the iron powder can be easily separated by using a magnet. The separated and recovered platinum group metal-supported alumina coat layer is treated by, for example, a method of eluting the platinum group metal from the catalyst layer with aqua regia or a method of eluting the platinum group metal with hydrochloric acid and chlorine gas. Recover platinum group metals.

[0007]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples. Example 1 A metal foil carrier of Fe-20Cr-5Al (400 cells, 1.3 L) was oxidized, and 260 g of an alumina coating layer was applied to the metal foil carrier. The catalyst was treated with sandblasting using iron powder for 5 minutes, and a filter and a magnet were used. When the alumina coat layer was separated and collected, the recovery rate of the alumina coat layer was 99% or more. Example 2 A catalyst prepared by carrying Pt 1.46 g and Rh 0.146 g on a metal foil carrier coated with an alumina coat layer in Example 1 was treated by sandblasting to separate and recover the alumina coat layer, and a conventional acid using aqua regia was used. When the platinum group was separated by the elution method, the recoveries of platinum and rhodium were Pt = 98% and Rh = 97%. Example 3 A catalyst prepared by supporting Pd 1.46 g and Rh 0.146 g on a metal foil carrier coated with an alumina coat layer in Example 1 was treated by sandblasting to separate and recover the alumina coat layer, and the same procedure as in Example 2 was conducted. When the platinum group metal was separated by the acid elution method, the recovery rates of palladium and rhodium were Pd = 98% and Rh =
It was 97%. Example 4 The metal foil carrier catalyst obtained in Example 2 was exposed to the exhaust gas of an actual engine at 850 ° C. for 100 hours, and platinum and rhodium were separated by the same method.
%, Rh = 96%. Comparative Example 1 As in Example 4, the metal foil carrier catalyst exposed in the engine exhaust gas was immersed in 5 L of a 20 wt% sodium hydroxide solution,
Leached overnight at ℃. After cooling, the platinum group metal was separated by filtration, dissolved in aqua regia, denitrated, and then separated from platinum and rhodium by a conventional separation method in which platinum was precipitated with ammonium chloride.
As a result, the recovery rates of platinum and rhodium were Pt = 82% and Rh = 68.
%Met.

[0008]

As described above, according to the present invention, only the alumina coat layer can be peeled from the metal foil carrier catalyst without using chemicals. Since only the alumina coat layer can be separated, the platinum group metal can be recovered in the same manner as the ceramic carrier catalyst. Therefore, it can be expected that the platinum group metal can be recovered from the used metal foil carrier catalyst which is considered to be generated in the future, and the effective activity of the resource can be achieved.

Claims (1)

[Claims] 1. A metal foil carrier catalyst is treated by sandblasting using iron powder as a grindstone to physically peel off an alumina coat layer carrying a catalytically active component composed of a platinum group metal, and the alumina coat layer and the grindstone. A method for recovering a platinum group metal from a metal foil carrier catalyst, characterized in that the platinum group metal is recovered by separating and recovering only the alumina coat layer and treating only the alumina coat layer with a chemical.