JPH05309221A - Cleaning method - Google Patents

Abstract

PURPOSE: To leave a metal catalyst existing in pores of a sinter and to clean the sinter until gas formation ceases by treating the sinter used for filtration of metal catalyst suspension with an aqueous solution of hydrogen peroxide. CONSTITUTION: In a cleaning apparatus of a first metal filter of hydrogen peroxide plant, a cover 2 of a filter unit having a sinter 3 is disposed between an upper part 4 and a lower part 5 of a cleaning tank 1. Upon cleaning an aqueous solution of hydrogen peroxide is conducted from a container 6 along the tube 16. Thus the aqueous solution of hydrogen peroxide flows from the upper part 4 into the sinter 3, that is, to their so called clean side and through the sinter 3 into the lower part 5, that is, to the so called dirty side. That is, the solution of hydrogen peroxide flows in the opposite direction of the direction in which a metal catalyst suspension flows during the filtering of the metal catalyst in the catalytic hydrogenation of anthraquinone or the like and releases the metal catalyst caught in the pores of the sinter 3. And ceasing of gas formation indicates that no significant quantities of metal catalysts are left.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a filter, and more particularly to a method for cleaning a sintered product used for filtering a metal catalyst suspension. The present invention is particularly directed to a filter consisting of a number of sinters and contaminated by the effluents from catalytic hydrotreating of anthraquinone or its derivatives, i.e. for the purification treatment of primary filter units of hydrogen peroxide plants. Suitable for cleaning unit equipment.

[0002]

Hydrogen peroxide is produced by the so-called anthraquinone process, as is well known in the art. In the process, the anthraquinone derivative is dissolved in an organic solvent consisting of one or more components. The solution thus produced is commonly referred to as a treatment solution and is first treated in a hydrotreating step. In the hydrotreatment, a part of the anthraquinone derivative is reduced by hydrogen gas to the corresponding anthraquinone derivative in the presence of a catalyst. The catalyst is separated from the treatment solution in the next step, i.e. before the oxidation. This separation of the catalyst is most often done by filtration. In the oxidation stage, the anthraquinone derivative is oxidized by air or oxygen and is the opposite of the previous hydrogenation state, that is,
Return to anthraquinone derivative. At the same time, hydrogen peroxide is produced. The hydrogen peroxide thus produced is separated from the treatment solution by being extracted with water. After extraction, the treatment solution is dried and back-treated for hydrogenation. The aqueous solution of hydrogen peroxide obtained by the extraction stage is purified and condensed. (Kirk-Othmer, Encyclopedia of
Chemical Technology, 3 panios, Vol. 13 , pages 16-
(See 21)

[0003]

In order to separate a suspension catalyst produced by filtration, for example, a ceramic or metal sintered product filter (Chemical Processing, January 1982, p.
age 24) as well as carbon filter (DE-PS-1,27
See also 2,292). In the repeated filtration process, the filter gradually blocks despite the use of a recleaning system.

It is an object of the present invention to provide a process for cleaning sintered metal or ceramic articles more effectively than before. The sintered product is used to filter a metal catalyst suspension of fine powder metal catalyst that has entered the pores.

The sintered metal filter is typically removed from the cover plate of the primary filter unit and placed in a basin, where the filters are separately submerged in the processing solution. The water washing process consists of several steps that require some human intervention and is therefore cumbersome and time consuming.

Therefore, another object of the present invention is to remove the filter unit from the cover plate of the filter unit, which is made up of a large number of sinters and is contaminated by the emissions from the catalytic hydrotreating of anthraquinone or its derivatives. It is an object of the present invention to provide a method for cleaning without removing individual sintered products. Therefore, the present invention is very suitable for cleaning filters used to separate precious metal catalysts. Further, it is suitable for washing the filter used for filtering the noble metal catalyst in the hydrogen peroxide production process.

US Pat. No. 4,113,613 discloses, as is well known in the prior art, a device comprising a fixed filter consisting of a rough base such as a sand filter by catalytically generating bubbles in the layer. ing. The bubbles trap the coarse filter material, which makes the filter more permeable as a dry filter. This technique does not give any suggestions regarding the cleaning of sintered articles. However, it does offer suggestions as to how to improve the characteristics of layers of filter rough material.

[0008]

The cleaning method of the present invention is a method for cleaning a sintered product used for filtering a metal catalyst suspension, which is generated by decomposition of hydrogen peroxide generated by a metal catalyst. The gas that is present indicates that there is no substantial amount of metal catalyst in the sintered product in order to replace the metal catalyst present in the pores of the sintered product, until the gas production is stopped until the gas production is stopped. It is characterized in that the product is treated with an aqueous hydrogen peroxide solution, whereby the above object is achieved.

The cleaning method of the present invention also uses a filter unit having a large number of sinters and contaminated with materials from the catalytic hydrotreating of anthraquinone or its derivatives to dissolve the anthraquinone or its derivatives. A method of cleaning by solvent cleaning with a liquid of a solvent, and steam cleaning the filter unit to liberate the solvent, wherein the solvent-cleaned and steam-cleaned filter unit comprises
Treated with 50% aqueous hydrogen peroxide solution for a sufficient amount of time or a sufficient number of times so that it is substantially gas-free, after which the filter unit is washed with water and finally dried. That is, the above object is achieved.

In particular, the filter unit is treated with a dilute aqueous hydrogen peroxide solution at 5 to 15 percent, for example about 10 percent.

The water washed filter unit melts the metal catalyst prior to subsequent hydrogen peroxide treatment, water washing and final drying in order to more completely remove the metal catalyst from the sintered product in the filter unit. It is washed again with the warm acidic aqueous solution.

The purifying effect is obtained by washing the filter unit after the solvent washing and the steam washing with the warm alkaline aqueous solution before the actual hydrogen peroxide treatment.
Further strengthened. The washing process is further enhanced by treating the filter unit before it is washed with the aqueous hydrogen peroxide solution and the aqueous alkaline solution and then with water.

As the acidic aqueous solution, a 10-50% nitric acid aqueous solution is used, for example, at a temperature of 20-80 ° C. Particularly, a nitric acid aqueous solution of 25 to 35%, for example, about 30% is
It is preferably used at 0 to 70 ° C, for example, about 65 ° C.

The alkaline aqueous solution is 1 to 20 ° C.
(Preferably about 5%), 70 to 90 ° C, for example 80 ° C
To the extent that aqueous sodium hydroxide solution is used.

The percentages shown here are volume percentages unless otherwise specified.

The cleaning method according to the invention is particularly suitable for cleaning ceramic or metal porous sintered products. The sinter is used to filter precious metal catalysts, especially palladium black.

[0017]

The cleaning method of the present invention is extremely excellent in that the generation of gas generated by the decomposition of hydrogen peroxide is particularly concentrated in the pores of the metal catalyst in the filter having the above metal catalyst. There is. The produced gas effectively "collides" with the fine powder metal catalyst emerging from the pores of the sintered article. The advantage of this method is that gas production stops when a substantial amount of the metal catalyst disappears in the pores of the sintered product, which makes it easy to determine that the sintered product has been sufficiently purified. ..

The cleaning method according to the invention is particularly suitable for cleaning filter units which consist of a large number of sinters and which are contaminated by the effluents from the catalytic hydrotreating of anthraquinone or its derivatives. This eliminates the need for separate sintered products from the cover plate of the primary filter unit. Along with this, there is no need to separate the sintered products, and at the same time, there is no risk of the individual sintered products being destroyed. The cleaning method of the present invention also substantially reduces the need to seal the filter. Further, according to the present invention, it is no longer necessary to separate individual sintered products from the filter unit, which is effective from the viewpoint of such occupational hygiene.

[0019]

The details of the present invention will be described below. FIG. 1 shows a schematic of a cleaning device suitable for carrying out the process of the invention.

FIG. 1 shows a cleaning device for cleaning a metallic primary filter of a hydrogen peroxide plant. The actual wash tank is indicated generally by the reference numeral 1.
The cleaning tank has an upper part 4 and a lower part 5, and a cover 2 of a filter unit having a sintered product 3 is firmly attached in a detachable state between them. The metal sinter 3 is an elongated filter element attached to the lower end, the open upper ends of which are positively connected to the openings evenly arranged in the cover 2. As a result, the steam between the upper side and the lower side of the cover 2 passes through the opening and the sintered product 3 bonded to the cover 2
Pass through the wall.

Dry air is introduced into the upper part 4 of the tank 1 from inside the tube 14. The tube 14 is equipped with a heat exchanger 12 'for heating the dry air by means of steam 13', which is taken out of the heat exchanger 12 'as a compressed product 15'. Steam is directly introduced into the upper portion 4 from the pipeline 13. Reference number 17
Relates to an exhaust pipe which is connected to the upper part 4.
Further, the hydrogen peroxide aqueous solution is supplied from the container 6 to the tube 16
Is transported along. Thus, the aqueous hydrogen peroxide solution flows from the upper part 4 into the sintered product 3 toward the so-called clean side, passes through the sintered product 3 to the lower part 5, that is, toward the so-called contaminated side of the sintered product 3. Flowing. In other words, the hydrogen peroxide solution flows during the filtration of the metal catalyst in the anthraquinone or its derivative in the direction opposite to the direction in which the catalyst suspension of the metal flows. This is a particularly effective mode, and helps release the metal catalyst trapped in the pores of the sintered product 3. This is because the metal catalyst can easily move in the original direction. That is, when hydrogen peroxide decomposes, water and oxygen gas are produced, which are
The pressure applied to the clean side of the sintered product 3 was increased to such an extent that different pressures were generated between the clean side and the contaminated side, and the metal catalyst trapped in the pores of the sintered product 3 as a filter component. Is removed from the pores in the same direction that the catalyst entered the pores.

The cleaning unit further comprises a container 7 of nitric acid aqueous solution, a container 8 of alkaline aqueous solution and a container 9 of water, which are selectively arranged in the lower part 5 of the cleaning tank along the tube 11. Supplied. The pipeline 11 also has a heat exchanger 12 for indirectly heating the above-mentioned flow by means of steam 13.

At the upper part of the lower part 5 of the cleaning tank 1, a drain pipe 18 for overflowing the cleaning solution from the lower part, a bottom part of the lower part 5 of the cleaning container 1, and the containers 6, 7, 8, 9 are provided. Through the discharge pipe 19 connected to the attached filter 10, each container 6,
A pipe 20 for returning the corresponding liquid to 7, 8, 9 is attached. The pore size of this filter 10 is
It must be smaller than the pore size of the sintered metal article to prevent solvent impurities from entering each container 6, 7, 8, 9. It goes without saying that new solutions are added to the vessels 6, 7, 8, 9 if necessary.

The method of the present invention is implemented by such a system as follows.

As shown in the figure, the so-called short-term cleaning process is carried out in the cleaning unit of the hydrogen peroxide plant.

A cover 2 (trade name "Pall Filters PSS" Pall in one filter unit having the sintered product 3
Corporation, Great Britain), the filter unit is re-cleaned together with a solvent component (aromatic hydrocarbon) and then fed into the cleaning tank 1. In the upper part 4 of the washing tank 1, ie on the so-called clean side, the filtered vapor 1
3 (about 2-2.5 atmospheres (aty), 135-140 ° C.) is introduced, and its vapor is discharged through the ventilation tube 18 on the contaminated side while a small amount of compressed material remains in the washing tank 1. To be done. The ion-exchange purified water 9 is steam-washed, and then is injected into the contaminated side of the filter component through the heat exchanger 12 (65 ° C.) and the tube 11 for about 15 minutes. Water from the contaminated side is overflowed 20 from the lower part 5 of the wash tank 1 through the filter 10 back into the water tank 9. Next, for about 20 minutes
Dilute aqueous hydrogen peroxide solution _{(10% H 2 0 2)} 6 , the room temperature (20
C.) through the filter component 3 and from the clean side of the tank 1 into the contaminated side. After the hydrogen peroxide treatment, it is washed with water (as described above, 65 ° C., 15 ° C.).
Minutes). Prior to the final drying, the sinter 3 is heated on the clean side for 15 minutes by the steam 13 introduced. The uncompressed vapor is conveyed into the ventilation tube 18 and the compressed matter is conveyed into the water tank 9 at the end of the steam cleaning. Finally, the dried product of the sinter is reduced to about 20 by the filtered hot (105 ° C.) compressed air 14 introduced.
It is carried out for a minute. The air is then displaced through the ventilation tube 18 on the contaminated side.

A second embodiment of the cleaning method of the present invention will be described below.

The cleaning method of this embodiment is also carried out by the cleaning system shown in FIG.

The cover plate 2 (trade name “Pall Filter PS
S ”) is sucked up into the wash tank 1. Before the transportation, the sintered product 3 is washed with an organic solvent. First, in the upper part 4 of the washing tank 1, the so-called clean side, steam 1
3 (2-2.5 atm, 135-140 ℃) was introduced,
The vapor may be discharged through the ventilation tube 18 on the contaminated side. Then, a small amount of the compressed product thus produced remains in the cleaning tank 1. Following such steam flow, ion-exchange purified water 9 is fed through the heat exchanger 12 on the contaminated side of the sintered article 3 for about 15 minutes. From the contaminated side of the wash tank 1, water is transported as drainage into the water tank 9 through the filter 10.
Then, for 20 minutes, dilute aqueous hydrogen peroxide solution (10
%) 6 is fed from the clean side to the contaminated side through the sintered article 3 at room temperature. Following the hydrogen peroxide treatment, cleaning with water is performed (same as the previous time, 65 ° C., 15 minutes).
After washing, preheated nitric acid solution (30%)
7 was again fed from the heat exchanger 12 to the cleaning tank 1 on the contaminated side of the sintered product 3 at a temperature of 65 ° C. From the contaminated side of the cleaning tank 1, the nitric acid aqueous solution was discharged as drainage 20. It is fed to the nitric acid tank 7 through the filter 10. After acid treatment, wash with water (65 ℃, 15
Minutes). Prior to final drying, the sinter 3 is heated by the steam 13 introduced on the clean side for 15 minutes. The uncompressed vapor is fed into the ventilation tube 18 and the compressed product is introduced into the water tank 9 at the end of the vapor treatment. Finally, the dried sinter 2 is treated with the filtered hot (105 ° C.) compressed air introduced for 20 minutes on the clean side, and the air is exhausted through the ventilation tube 18 on the contaminated side.

Further, a third embodiment of the cleaning method of the present invention will be described below.

This embodiment is also carried out by the cleaning system shown in FIG.

The cover plate 2 in one filter unit having the sintered product 3 (trade name "Pall Filters P
SS ”) is lowered into the water tank 1. The filtered steam 13 (2-2.5 atm, 135-140 ° C.) is introduced into the so-called clean side in the upper part of the washing tank 1. This vapor is the ventilation tube 18 on the contaminated side.
Exhausted through. Then, a small amount of the compressed product thus generated remains in the water tank 1. The preheated alkaline solution 8 (5% NaOH) is used in the heat exchanger 12.
Through the tube 11 at about 80 ° C. for 30 minutes to the washing tank. From wash tank 1,
The alkaline solution is returned as drainage 20 through the filter 10 to the alkaline solution container 8. During evaporation,
The decomposed catalyst and the alkali cleaning are decomposed by the filter 10 in the alkali cycle. After alkaline cleaning, the solution is separated from the cleaning tank through tube 19.
After the alkali cleaning, the purified ion-exchanged water 9 is used in the heat exchanger 1
1 through the contaminated side of the sintered product at about 65 ° C through 2
Delivered over 5 minutes. The water discharged as the overflow 20 is returned from the contaminated side to the water tank 9 through the filter 10. Then, for about 20 minutes, dilute aqueous hydrogen peroxide solution (10%) 6 is fed from the clean side to the contaminated side through the filter 10 at room temperature (20 ° C.). Following the hydrogen peroxide treatment, washing with water is performed (as in the previous time, 65 ° C., 15 minutes). Next, the preheated nitric acid solution 7 (30%) is fed into the wash tank at about 65 ° C. through the heat converter 12 and the tube 11.
Again, it returns to the contaminated side of the sintered product 3. From the contaminated side of the wash tank 1, the nitric acid solution is treated as an overflow 20 and returned to the nitric acid container 7 through the filter 10. After the acid treatment, washing with water (65 ° C., 15 min), hydrogen peroxide treatment _{(10% H 2 0 2,} 20 ℃, 20 minutes), water cleaning (65 ° C., 15 minutes) is performed. Before the final drying, the sintered product is 1
Heat for 5 minutes. The uncompressed vapor is fed to the ventilation tube 18, and the compressed product is introduced into the water tank 9 after the vapor cleaning is completed. Finally,
The dried product of the sinter is filtered to a high temperature (105
C.) compressed air for 20 minutes on clean side. And the air is the ventilation tube 1 on the contaminated side.
Exhausted from 8.

[0033]

With the cleaning method of the present invention, a very successful final result is obtained as compared with a treatment that is simply mixed with hydrogen peroxide.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cleaning system used for carrying out a cleaning method of the present invention.

[Explanation of symbols]

 1 Cleaning tank 2 Cover 3 Sintered product 12 Heat exchanger

Claims (10)

[Claims] 1. A method for cleaning a sintered product used for filtering a metal catalyst suspension, comprising the steps of: Treating the sintered article with an aqueous solution of hydrogen peroxide until the production of gas is stopped, which is shown to be depleted of the metal catalyst in the sintered article in order to replace the metal catalyst present in the sintered article. A method for cleaning a sintered product, comprising: 2. A filter unit having a large number of sinters and contaminated with substances from the catalytic hydrotreating of anthraquinone or its derivatives, and a solvent of the solvent used to dissolve the anthraquinone or its derivatives. A method of cleaning by cleaning and steam cleaning the filter unit to liberate the solvent, wherein the solvent-cleaned and steam-cleaned filter unit is a 5-50% aqueous hydrogen peroxide solution. A cleaning method, characterized in that it is treated for a sufficient time or a sufficient number of times so that substantially no gas is generated, after which the filter unit is washed with water and finally dried. 3. A cleaning method according to claim 2, characterized in that the filter unit is treated with an aqueous solution of hydrogen peroxide of 5 to 15%, for example 10%. 4. The filter unit washed with water is washed with a warm acidic aqueous solution in which the metal catalyst is melted before being newly treated with hydrogen peroxide, washed with water and finally dried. The cleaning method according to claim 2 or 3. 5. The filter unit according to claim 4, wherein the filter unit is washed with a warm alkaline aqueous solution and with water after the solvent cleaning and the steam cleaning and before the hydrogen peroxide treatment. Cleaning method. 6. The cleaning method according to claim 5, wherein the filter unit is treated with an aqueous hydrogen peroxide solution and washed with water before being washed with the warm alkaline aqueous solution. 7. A 10 to 50 percent aqueous nitric acid solution is 2
It is used at 0 to 80 ° C. 7.
The cleaning method according to any one of 1. 8. The cleaning method according to claim 7, wherein a nitric acid aqueous solution of 25 to 35%, for example, about 30% is used at 60 to 70 ° C., for example, about 65 ° C. 9. 1-20%, preferably 5%
An aqueous solution of NaOH is 20 ° C or higher, preferably 70 to 90 ° C,
The cleaning method according to any one of claims 5 to 8, which is used at, for example, about 80 ° C. 10. A cleaning method according to any of the preceding claims, characterized in that the ceramic or metal sinter used to filter the noble metal catalyst, in particular palladium (Pd), is cleaned.