DE2042523B2 - PROCESS FOR REGENERATING PRECIOUS METAL CATALYSTS FOR HYDROGEN PEROXIDE SYNTHESIS BY THE ANTHRACHINONE PROCESS - Google Patents

Description

So-called regeneration containing anthraquinone compounds is used.

Unemployment in the circle back in the hydrogenation guided. The point of view was that unchanged hydrogen-In this cycle it comes to undesirable peroxide, i.e. the active oxygen, although no noticeable side reactions, in which compounds the damaging one, but at least one damaging one of the most varied types. As should have a special effect on the catalyst. Extremely disturbing have become resinous and decomposition should the unemployment with constant cycle breakdown products proven unexplained constitution. guided by the constant presence of water-this Compounds, for example, cause all-substance peroxide to be changed. It was now showing gradual decrease in the activity of the hydrogenation, surprising that in the presence of hydrogen cycle, resulting in excessively high catalyst costs peroxide preserve the catalyst in its activity compared to the total cost of production and unemployment was not attacked. Even Hydrogen peroxide. Usually the work is done after constant circulation in its activity -diminished or used 55 solution in tact. Even the selectivity of the catalyst The catalyst was removed from the system and remained unchanged.

It is even possible to use a catalyst whose

but at least the hydrogenation tower during the regeneration activity through the circulation of the hitherto customary ones

ration switched off. In particular when working with working solution egg has decreased due to the addition of

Fixed-bed hydrogenation makes this working 60 hydrogen peroxide in the specified amounts

wisely noticeable as time consuming and costly. to regenerate back to the old values. To this

So far, however, there is still no really usable way of removing the costly

Process for reactivating the catalyst in situ playful regeneration apparatus, which also

known. Demand, avoid extensive maintenance.

It is true that according to German patent specification 1 055 513 65, the special stages required in addition to the actual

a resuscitation process for the hydrogenation catalysis regeneration yes also various washing pre-

Sator of the anthraquinone process indicated after gears to make the catalyst fully operational again

to make the catalyst in the hydrogenation stage a periodic one. Certain losses also occurred here

3 4

Catalyst metal, d. H. of precious metal, on; it is any interruption of the overall

because, the oxidizing agents and detergents were developed. Besides, the working solution - too

appropriately worked up with long-term circulation - not

In the method according to the invention, a deficiency is damaged

from 300 to 1000 mg hydrogen peroxide per liter 5 The invention is based on the following

Working solution preferred. Examples explained:

This amount of hydrogen peroxide can either be Example 1
by a correspondingly lower extraction with

Water or desorption with organic vapors in a working solution consisting of 150 g / l ethyl

the working solution remain, or it can be in the io anthraquinone and lSOg / lTetrahydroäthylanthraquinone

Working solution after extraction or desorption in a mixture of 60 parts by volume of tributylphosphate

be adjusted again, either by adding phat and 40 parts by volume of methylnaphthalene (= techn.

a side stream from the oxidation or by mixing the isomers 1 and 2) was over at 60 ° C

Adding 100% hydrogen peroxide or a fixed bed contact (0.3% Pd on pebble)

highly concentrated aqueous solutions. This high - 15 corresponding to a hydrogen peroxide content of

concentrated aqueous solutions can be hydrogenated at 30 g / l and, after fine filtration, with air

most professional and economical by extraction of the 60 ⁰ C in an oxidation tower to anthraquinone /

according to German patents 1 802 003 and tetrahydroanthraquinone and hydrogen peroxide

1951211 accruing solutions with re-oxidized accordingly. The hydrogen peroxide was using

Produce small amounts of water (see German Offen- 20 Butyl acetate desorbed. The from hydrogen peroxide

document 20 42 522). set aside work solution, either a residual salary

It is only essential that the working solution contained 0.3 g / l hydrogen peroxide or the medium

enters the hydrogenation tower the minimum amount of reac- a side stream from the oxidation or with the aid

possesses capable hydrogen peroxide. of 10% by weight hydrogen peroxide in butyl acetate

The support for the catalyst is silica 25 with a content of 0.3 g / l hydrogen peroxide

Acidic materials as well as aluminum oxides or had been brought into the hydrogenation tower

Activated carbon in question. returned. After 1200 hours, the hydrogenation

As a suspension contact, the catalysts cannot yet reduce their activity,

how to be used as fixed bed catalysts. Example 2

The regeneration according to the invention is suitable

- as I said - both for a system with water A working solution according to Example 1 was up to

extraction as for a system with desorption of a residual content of 0.001 g / l hydrogen peroxide from

Hydrogen peroxide from organic vapors. Freed in hydrogen peroxide. After 12 hours it was

in the latter case it is particularly effective since the degree of hydrogenation has fallen so far that it is only 20 g / l

Experience has shown that hydrogenation catalyst there corresponded more rapidly to hydrogen peroxide. After that, the

fatigued than with water extraction. Working solution desorbs to a residual content of

The technical progress of the present invention, 0.5 to 0.8 g of hydrogen peroxide per liter of working manure, therefore lies in avoiding the separate dissolution and the working solution in the hydrogenation generation levels and their difficulties. After another 12 hours the with complete retention of the catalytic effect achieved again without full hydrogenation activity.

Claims (1)

ι 2 Reduction of the hydrogen peroxide pressure below Claim: Simultaneous introduction of inert gas is exposed. However, the hydrogenation itself must take place during this time Process for the production of hydrogen - either very throttled or even completely under- peroxide according to the anthraquinone method in 5 are broken. The presence of hydrogenation catalysts on supports was also known to increase the catalyst activity by means of germ materials from the platinum metal group by setting a certain amount of water in the Ar-Periodic Table, preferably palladium starting solution (see U.S. Pat 867 507). However, this could not be used to moor the platinum group - and to prevent the regeneration of the io, that in the course of time the hydrogenation catalyst obtained in this way, whereby the working solution gradually decreased due to poisons which were brought into the hydrogenation with the working solution when they re-entered the hydrogenation stage,
a content of reactive hydrogen after the process of the German patent peroxide of at least 250 mg / 1 working solution 913 888 is indeed an unemployment that has after, characterized in that the 15 extraction with water still 0.01 to 0.03 mol Water-noble metal catalysts at full performance are substance peroxide that remained in the hydner stage of the hydrogenation stage with that from the extraction and / or again. The used or inactive desorption step coming unemployment without hydrogenation catalyst but after separate separation during the hydrogenation of this process must be removed from the unemployment and regenerated. 20 can be reactivated in a separate stage with the aid of an oxidizing agent. So it was previously unknown, the regeneration carry out the hydrogenation catalyst itself at full performance in the hydrogenation stage. The invention relates to a method for in-situ 25 In contrast, it has now been found that in the Regeneration of noble metal catalysts in the preparation of hydrogen peroxide after the preparation thrachinone process, in which the active metal is a thraquinone process, the reactivation of hydration Metal of the platinum group of the periodic table in catalysts on support materials from the Mixture with other metals of the platinum group of the platinum metal group of the periodic table, before- Periodic table preferably used on supports, preferably palladium - optionally in a mixture will. with other platinum group metals - essential It is well known that hydrogen peroxide can be used in a recycle at least Cycle process are produced in which anthraquinone has 250 mg hydrogen peroxide per liter, combined compounds alternately hydrogenated and oxidized can fold when the noble metal catalysts will. Reduction and oxidation take place in a full driving performance of the hydrogenation stage without a separate one organic solvent or solvent mixture separation regenerated during the hydrogenation instead that both the anthraquinone and the become. Keeps anthrahydroquinone compounds in solution. That it was not foreseeable that the regeneration in the oxidation of the hydroquinone to the quinone of the noble metal catalysts by the remaining water Hydrogen peroxide formed is from the organic 40 hydrogen peroxide proceeds faster than the hydrogenation Phase isolated by known methods and the water. Therefore, special levels have been used so far