FI86380C - FOER REFRIGERATION FOR FILTER. - Google Patents

Description

1 86380

The present invention relates to a method for cleaning a filter and in particular a sinter used for filtering a metal catalyst suspension. The present invention is particularly well suited for the purification of a multi-sinter filter unit derived from the catalytic hydrogenation of anthraquinone or a derivative thereof, i.e. for the purification treatment of a primary filter unit of a hydrogen peroxide plant.

As is known, hydrogen peroxide can be prepared by the so-called anthraquinone-niprosessilla. In this method, the anthraquinone derivative 15 is dissolved in an organic solvent consisting of one or more components. The solution thus prepared, which is generally called a working solution, is first passed to a hydrogenation step. In the hydrogenation step, a portion of the anthraquinone derivative is reduced with hydrogen gas in the presence of catalyst 20 to the corresponding anthrahydroquinone derivative. Before the next step, oxidation, the catalyst is separated from the working solution. The separation of the catalyst is most often done by filtration. In the oxidation step, the anthrahydroquinone derivative is oxidized with air or oxygen, whereby it returns to its pre-hydrogenation form, i.e. to the anthraquinone derivative. At the same time, hydrogen peroxide is formed. The hydrogen peroxide formed is removed from the working solution by extraction with water. After extraction, the working solution is dried and returned to hydrogenation. The aqueous hydrogen peroxide solution obtained in the extraction step is purified and concentrated (Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd edition, Vol. 13, pages 16-21).

For the separation of the suspension catalyst by filtration, e.g. ceramic or metal sinter filters; 35 (Chemical Processing, January 1982, page 24) and carbon filters 2,86380 (DE-PS-1 272 292). In continuous filtration, the filters gradually become clogged despite the back-rinsing systems in use.

It is therefore an object of the present invention to provide a method for purifying a metallic or ceramic sinter used for filtering a metal catalyst suspension more efficiently from a fine metal catalyst which has penetrated its pores.

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Metal sinter filters are usually cleaned by removing them from the cover plates of the primary filter unit and transferring them to sinks, where they are loosely immersed in the washing solutions. The washing operation involves several craft steps 15 and is thus both cumbersome and time consuming.

It is therefore a further object of the present invention to provide a method for purifying a filter unit consisting of a plurality of Sint-20 blades from the catalytic hydrogenation of anthraquinone or a derivative thereof without removing individual sinter from the cover plate of the filter unit. The invention is thus well suited for the purification of filters used for the separation of noble metal catalysts and very particularly well for the purification of filters used in the hydrogen peroxide production process for the filtration of noble metal catalysts.

The main features of the invention appear from the appended claims.

In the process of the invention, the metallic or ceramic porous sinter is treated with an aqueous solution of hydrogen peroxide to displace the metal catalyst in the sinter pores by the gas generated by the decomposition of the hydrogen peroxide by the metal catalyst until gas evolution ceases to indicate that the sinter no longer contains significant amounts of metal catalyst.

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The process according to the present invention is thus highly selective, since the evolution of gas due to the decomposition of hydrogen peroxide is concentrated precisely on those pores in the sinter with a metal catalyst. The evolving gas 5 effectively "blows" the finely divided metal catalyst out of the sinter pores. The advantage of the method is that the evolution of gas ceases when there are no longer significant amounts of metal catalyst in the pores of the sinter, from which it can easily be stated that the sinter is sufficiently pure.

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The process according to the invention is particularly well suited for the purification of a multi-sinter filter unit derived from the catalytic hydrogenation of anthraquinone or a derivative thereof, whereby the individual sinter need not be removed from the cover plate of the primary filter unit. This avoids handling loose sinter and at the same time minimizes the risk of damage to individual sinter. With this solution, the need for sealing the filters is also substantially reduced. The invention also achieves the most economically advantageous solution when it is not necessary to remove individual sinks from the filter unit.

According to the invention, the filter unit rinsed as a solvent used for dissolving anthraquinone or a derivative thereof and then freed from the solvent by steam stripping is treated with a 5-50% aqueous solution of hydrogen peroxide until the gas no longer substantially evolves, after which the filter unit is washed with water and dried. finally.

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It has been found particularly advantageous to treat the filter unit with a dilute 5-15%, for example 10% aqueous solution of hydrogen peroxide.

35 The water-washed filter unit can still be washed with a warm aqueous solution of a metal catalyst dissolving acid before a further hydrogen peroxide treatment, water washing and final drying to more accurately remove the metal catalyst from the sinter units of the filter unit j 4 86380. The purification efficiency can be further enhanced by washing the filter unit after solvent rinsing and evaporation with a warm aqueous alkaline solution and rinsing with water before the actual hydrogen peroxide treatment.

The purification treatment can be further enhanced by treating the filter unit with an aqueous solution of hydrogen peroxide before washing with a warm aqueous aqueous solution and then performing a water wash.

As the aqueous acid solution, a 10-50% aqueous nitric acid solution having a temperature of 20-80 ° C can be used. It is particularly preferred to use a 25-35%, for example 30% aqueous solution of nitric acid at a temperature of 60-70 ° C, for example about 65 ° C.

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As the basic aqueous solution, 1 to 20%, preferably about 5%, aqueous sodium hydroxide solution having a temperature above 20 ° C, preferably 70 to 90 ° C, for example about 80 ° C, can be used.

20 In this context, all percentages are by volume unless otherwise indicated.

The process according to the invention is particularly well suited for the purification of ceramic or metallic porous sinter. which sinks have been used for the filtration of precious metal catalysts, in particular palladium black.

The invention will now be described in more detail with reference to the accompanying drawing, which shows a schematic, cross-sectional vertical view of a washing apparatus suitable for carrying out the method according to the invention.

The figure below shows a washing unit for cleaning primary metallic filters in a hydrogen peroxide plant. The arm-- · 'female wash tank is generally indicated by reference numeral 1 and consists of a top 4 and a bottom 5, between which ·'. the cover 2 of the filter unit with its sinter 3 can be tightly fitted. Metallisintterit 3 are closed at the lower end of elongate filter elements having an open upper end of the cover 2 is closely linked to a corresponding position in the opening so that the upper and the lower side of the cover 5 currents passing through said openings and associated sintte-3 esters of the walls.

Drying air is introduced into the upper part 4 of the tank 1 in a pipe 14 to which a heat exchanger 12 'is connected for heating the drying air by means of steam 13' which leaves the heat exchanger 12 'as condensate 15'. Steam can also be introduced directly into the upper part 4 from the pipeline 13. Reference numeral 17 denotes an outlet line associated with the upper part 4. In addition, an aqueous solution of hydrogen peroxide is introduced into the upper part 4 from the tank 6 via line 16 to 15. The aqueous hydrogen peroxide solution thus flows from the top 4 inside the sinter 3 to their so-called clean side and through the sinter to the bottom 5, i.e. the so-called dirty side of the sinter 3, i.e. in the opposite direction to the metal catalyst suspension flowing during the metal catalyst filtration or anthraquinone filtration. the hydrogenation. This contributes particularly effectively to the removal of the metal catalyst adhering to the pores of the sinter 3, since the metal catalyst is easier to remove in the direction from which it has come. The hydrogen peroxide decomposition generated 25 namely water and oxygen gas which raises the pressure in three clean side travertine, so that the travertine three clean and dirty side of a pressure differential which forces the filter elements 3 in the pores adhered to the metal out of the pores in the same way as they are for these into 30 mesh stack, displaced.

The washing unit further comprises tanks for an aqueous solution of nitric acid 7, an aqueous solution of lye 8 and water 9, which are fed alternately via a pipe 11 to the lower part 5, 35 of the washing tank 1, the pipe 11 also having a heat exchanger 12 for heating these flows indirectly by steam 13.

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The upper part of the lower part 5 of the washing tank 1 is further connected to an outlet line 18 and a line 20 for removing washing solutions from the lower part 5 as an overflow to return them to their tank 6, 7, 8 or 9 in an outlet pipe 19 connected to the bottom of the lower part 5 and each tank 6, 7, 8 and 9. through the associated filter 10. The pore size of the filters 10 should be smaller than the pore size of the metal sinter 3 to prevent solid contaminants from entering the tanks 6, 7, 8 and 9. Naturally, this fresh solution 10 is added to the tanks 6, 7, 8 and 9 as needed.

The invention is described in more detail below by means of examples.

15 Example 1

At the hydrogen peroxide plant, the so-called a short washing program with the washing unit according to the figure

The lid 2 of one filter unit with sinter 3 (Pall Filters 20 PSS, Pali Corporation, England) was lifted into the wash tank 1 after the filter unit was back-rinsed with the solvent component of the working solution (aromatic hydrocarbon). In the upper part of the washing tank 1 4 ns. the clean side of the steam introduced into the filtered 13 (2-2,5 ATY 135-140 ° C), vapor Other in-25 were to leave the dirty side hönkäputkesta 18 while receiving a resulting small kondenssimäärä remain in the washing tank 1. After the vapor deposition was pumped into the preheated ion exchanger, pure water Tua 9 through the heat exchanger 12 (65 ° C) and line 11 to the dirty side of the filter element 3 for about 15 to 30 minutes. From the dirty side, the water was led from the lower part 5 of the washing tank 1 overflow 20 through the filter 10 back to the water tank 9. Next, a dilute (10% H2O2) room temperature (20 ° C) aqueous hydrogen peroxide solution was pumped from the tank 6 through the filter elements 3 for about 20 minutes. (as above 65 ° C, 15 min.). Prior to final drying, the sinter 3 was heated by passing steam 13 to its clean side for about 5 minutes, uncondensed 7 86380 steam was passed to a tubing 18 and condensation at the end of evaporation to a water tank 9. Finally, the sinter 3 was dried by passing hot air at 105 ° to the clean side. for about 20 minutes, air 5 is removed from the dirty side 18 hönkäputkesta.

Example 2

At the hydrogen peroxide plant, the so-called a medium washing program with the washing unit 10 according to Fig. 1

The cover plate 2 of one filter unit with its sinter 3 (Pall Filters PSS) was lifted into the washing tank 1. The sinter 3 had been rinsed before transfer as an organic solvent. First, the top of the washing tank 1 4 ns. the clean side of the guide rod 15, the steam is filtered 13 (2-2,5 ATY 135-140 ° C), vapor was allowed to leave the dirty side hönkäputkesta 18 and the resulting small kondenssimäärä was left after washing tank 1. The vapor deposition was pumped into a clean, deionized water heat exchanger 12 9 ( 65 ° C) through the sinter 3 to the dirty 20 sides for about 15 minutes. From the dirty side of the wash tank 1, water was returned to the water tank 9 via an overflow 20 through a filter 10. Next, a dilute (10%), room temperature (20 ° C) aqueous solution of hydrogen peroxide 25 was pumped through the sinter 3 for about 20 minutes 6. Hydrogen peroxide treatment followed by water rinsing 65 ° C, 15 min.). After rinsing with water, the preheated nitric acid solution 7 (30%) was pumped through the heat exchanger 12 to the washing tank 1 at about 65 ° C, again to the dirty side of the sinter 3. From the dirty side of the wash tank 1, the nitric acid solution was passed back to the nitric acid tank 7 via an overflow 20 through a filter 10. After the acid treatment, a water rinse was performed (65 ° C, 15 min.). Prior to final drying, the sinter 3 was heated by passing steam 13 to its clean side for about 5 minutes, uncondensed steam 35 was passed to a tubing 18 and condensation at the end of evaporation to a water tank 9. Finally, the sinter 3 was dried by passing filtered (8,86380) to the clean side. compressed air 14 to about 20 minutes, removed from the dirty air side 18 hönkäputkesta.

Example 3 At a hydrogen peroxide plant, a so-called long washing program with the washing unit according to the figure

The cover plate 2 of one filter unit with its sinter 3 (Pall Filters PSS) was lifted into the washing tank 1. In the upper part of the washing tank 1 10 4 ns. the clean side of the steam introduced into the filtered 13 (2-2,5 ATY 135-140 ° C), vapor was allowed to leave the dirty side hönkäputkesta 18 and the resulting small kondenssimäärä was left washing tank 1. A pre eight sodium hydroxide solution (5% NaOH) was pumped through the heat exchanger 12 to about 15 At 80 ° C to the wash tank via line 11 for about 30 minutes. The liquor from the washing tank 1 escaped in an overflow 20 through the filter 10 back to the liquor tank 8. The catalyst detached during the evaporation and lye washing was separated by a lye circulation filter 10. After the alkali washing was completed, the solution was drained from the 20 washing tanks via line 19. After the alkali wash, pure, deionized water 9 was pumped through the heat exchanger 12 at about 65 ° C to the dirty side of the sinter for about 15 minutes. From the dirty side, the water was led back to the water tank 9 via an overflow 20 through a filter 10.

Next, a dilute (10%) room temperature (20 ° C) aqueous hydrogen peroxide solution 6 was pumped through the sinter 3 for about 20 minutes. The hydrogen peroxide treatment was followed by a water rinse (as above 65 ° C, 15 min.). Next, the preheated nitric acid-30 stream 7 (30%) was pumped through the heat exchanger 12 and line 11 to the wash tank at about 65 ° C again on the dirty side of the sinter 3. On the dirty side of the washing tank 1, the nitric acid solution was returned to the nitric acid tank 7 via an overflow 20 through a filter 10. After the acid treatment, a water-35 rinse (65 ° C, 15 min.) And a hydrogen peroxide treatment (10% HaOa, 20 ° C, 20 min.) (65 ° C, 15 min.). Prior to final drying, the sinter 3 was heated by passing steam 13 to its clean side for about 5 minutes, 9,86380 non-condensable steam was passed to a tubing 18 and condensate at the end of evaporation to a water tank 9. Finally, the sinter 3 was dried by passing about 14 ° C to the clean side. 20 min at 5, the air removed from the dirty side 18 hönkäputkesta.

The washing programs according to the invention give a very particularly good result compared to treating the filter unit with an aqueous solution of hydrogen peroxide alone.

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Claims (10)

A method for purifying a sinter used to filter a metal catalyst suspension, characterized in that the sinter is treated with an aqueous solution of hydrogen peroxide to displace the metal catalyst in the pores of the sinter 5 by a gas generated by the metal catalyst catalyst decomposition A process for purifying a sintered filter unit derived from the catalytic hydrogenation of anthraquinone or a derivative thereof according to claim 1 by rinsing the filter unit as a solvent used to dissolve anthraquinone or a derivative thereof and evaporating the filter unit to remove the solvent therefrom. with a% aqueous solution until the gas is substantially no longer evolved, after which the filter unit is washed with water and finally dried. Process according to Claim 2, characterized in that the filter unit is treated with a 5-15%, for example 10%, aqueous solution of hydrogen peroxide. Process according to Claim 2 or 3, characterized in that the water-washed filter unit is washed with a warm, aqueous solution of a metal catalyst-dissolving acid before a further hydrogen peroxide treatment, water washing and final drying. Process according to Claim 4, characterized in that, after solvent rinsing and evaporation, the filter unit is washed with warm basic aqueous solution 35 and rinsed with water before the actual hydrogen peroxide treatment. 11 86380 Method according to Claim 5, characterized in that before washing with a warm aqueous aqueous solution, the filter unit is treated with an aqueous hydrogen peroxide solution and washed with water. 5 Process according to one of Claims 4 to 6, characterized in that a 10 to 50% aqueous solution of nitric acid at a temperature of 20 to 80 ° C is used. Process according to Claim 7, characterized in that a 25-35%, for example about 30%, aqueous solution of nitric acid at a temperature of 60-70 ° C, for example about 65 ° C, is used. Process according to one of Claims 5 to 8, characterized in that an aqueous solution of 1 to 20%, preferably about 5%, of NaOH is used, the temperature of which is above 20 ° C, preferably 70 to 90 ° C. , for example about 80 ° C. Process according to one of the preceding claims, characterized in that the ceramic or metal sinter used for the filtration of the precious metal catalyst, in particular Pd black, is washed. i2 86380