DE2222120A1 - CATALYST FOR THE PRODUCTION OF HYDROXYLAMINE - Google Patents

Description

GENTEALA IKDUSTRIALA DE FIBER CHIMIGE Savinesti - Piatra Neamt - Romania

Catalyst for hydroxylamine generation

The invention relates to a platinum-based catalyst for the production of hydroxylamine by reducing nitrogen oxides, nitric acid, nitrate ion, etc. with hydrogen in a strongly acidic medium

The hydroxylamine is still non-catalytic Process like the Rashig process produces which low Yields and those difficult to utilize By-products. In the last few years, the more advantageous catalytic processes have become more and more popular by.

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Several processes are known for producing the hydroxylamine by catalytic ^ reduction of nitrogen monoxide, nitrogen dioxide, -trioxide, nitric acid or nitrate ion in a medium of strong mineral acid.

Catalysts based on platinum or platinum alloy are used here. The main reaction products are hydroxylamine and ammonia. The best conversions and yields are obtained with catalysts on inert carriers, such as carbon, graphite, silica gel or alumina, in a ratio of 0.3 to 13% platinum, in a 10 to 20% hydrochloric or sulfuric acid medium. The working temperature varies between -5 ° 0 and 100 ⁰ O, and the pressure between 1 ata and 10 ata. The ratio between hydrogen and nitrogen monoxide also varies between 1:10 and 10: 1, while the ratio between the catalyst and the acid, cca. 0.1 g of platinum per 300 cnr of acidic solution.

The catalyst is activated and regenerated on site by heating the reaction mixture to a temperature that is 10 - 40 ° 0 higher than the temperature at which the process is ahead goes, accompanied by the 5 minutes to 1 hour lasting Surge of hydrogen or nitrogen monoxide, after which the ongoing generation of the hydroxylamine is resumed by the addition of the mixture of hydrogen and nitric oxide.

It is also known that the selectivity of the cat-

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lysators through small additions of metals, such as Qu © eksilber, Lead or sulfur, selenium, etc., which are added during its preparation or in the reaction medium, can also be used for the purpose of Extension of the life of the catalyst, the acid used as the reaction medium, an oxidation treatment with Perhydrol, Oaro's Acid, Sodium Permanganate, etc.

Under such conditions, the hydroxylamine yields reach the nitric oxide conversion and the catalyst activity according to the most favorable - "- indications the following Values: 9O #, $ 95 and 64.7 g NO / g Pt.h. Less complete Data show that the activation and regeneration of the catalyst usually take place at intervals of a few Hours to be made.

On the other hand, one knows no effective experiences for them Activation of catalysts that have been poisoned by metal ions.

The known platinum catalysts for hydroxylamine synthesis have the following disadvantages: low activity and selectivity, low resistance to metal ion poisoning. In addition, theirs interrupt Activation and regeneration, which are carried out at high temperatures and at short intervals, the manufacturing process too often and lead to a modification of their intimate structure and implicit shortening of the Recuperation cycle.

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The invention eliminates the disadvantages of the catalysts known for this purpose.

The present invention provides a platinum-based catalyst, possibly with small additions of precious metals, This catalyst is on an inert carrier and is used for the production of hydroxylamine by the usual reduction of nitrogen monoxide, possibly of Nitric oxide or trioxide, from nitric acid, from " Nitration or from alkyl nitritea with hydrogen determined.

The catalyst according to the invention is produced by the reduction with excess formaldehyde in an alkaline medium of a concentrated hexachloroplatinic acid solution in the presence of an inert carrier, preferably graphite powder, the suspension being stabilized by a protective colloid such as gelatin, gluten, gum arabic, etc., ie reduction executed on a mixture whose temperature is tas. -JO ⁰ O to +100 ⁰ G, and takes at least 5 minutes, - ^ s are young about 0.05 to 5 g of protective colloid and 1 to 300 g of inert carrier for 1 g of platinum used.

After the reduction, the paste obtained is left at a Temperature from +10 to + 100 ° 0 for a minimum of 5 minutes, after which it is filtered while the catalyst washed on the filter with water.

The catalyst can often contain additions of precious metals, such as

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Gold, ruthenium, rhodium ", palladium, osmium or iridium, which in addition to the platinum in the original Hexachloroplatiascfcure are present

The washed and wet catalyst is activated by intensive contact with hydrogen in an acidic medium, preferably dilute sulfuric acid, at a temperature of +20 to 10O ⁰ G, for a minimum of 5 minutes, in the presence of small amounts of ferric chloride * There are 1 g Platinum 0.1 mg to 0.1 g ferric chloride used.

Activation takes place preferably in the hydroxylamine synthesis apparatus. Rapid and favorable results in terms of activation and synthesis are achieved by a continuously keeping the phases in contact, e.g. through Planetary motions in a horizontally lying device j the satellite waves carrying blades and with planetary mechanisms is provided »

In the following, the invention is based on three embodiments examples explained in more detail:

1) for the preparation of the catalyst and its Activation; ,

2) for the use of the catalyst in the hydroxylamine « symthesis and

3) for the activation and regeneration of the catalyst »

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example 1

For the reduction with formaldehyde in an alkaline medium, a solution of 24 ml of hexaehloroplatinic acid with 6 g of platinum content is prepared, which is heated to boiling and into which all supports 54 g of graphite powder and 4.15 g of alimentary gelatine are mixed as a protective colloid. The paste obtained is ^{stored in a lump cabinet at 60 °} C. for at least 30 minutes. The reduction is then carried out at ^{0 0 0 for} 30 minutes with 40% formaldehyde in excess with respect to the theoretically required amount in a strongly alkaline medium consisting of sodium hydroxide. After the end of the reduction, the presence of chloroplatinic ions can no longer be determined.

After reduction, the paste obtained is left to ^{rest at a temperature of 50 0} O for 2 hours, after which it is filtered while the catalyst on the support is washed with water on the filter until the chlorine ion disappears from the filtrate.

The washed catalyst is then activated by intensive contact with vase material in 25% strength Sulfuric acid medium with the addition of 1.5 mg ferric chloride at a temperature of 60 ° Ö for 30 minutes. the Activation takes place in the hydroxylamine synthesis apparatus, as shown in more detail in the following example.

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Example 2

A horizontal, cylindrical apparatus is used for the phase contacting, which is provided with a central drive shaft without blades and with three satellite shafts equipped with blades and which has a volume of 22 liters. && mg with an addition of ferric chloride are added 1.5 führts 12 1 sulfuric acid solution 25 $, 60 g PI _a tinkatalysator 1Q #, to graphite powder. The catalyst was prepared according to Example 1 and then it is activated.

The air is removed from the apparatus by washing with hydrogen. A pressure of 1.4 ata is maintained in the apparatus, the temperature of the reaction mixture is slowly increased to 60 ° 0 by heating through the jacket of the apparatus and the agitation, which lasts for 30 minutes, begins. The catalyst is now activated. It is activated now cooled in the same "ice to 25 ⁰ O and it begins the continuous supply of the reacting gases, hydrogen and nitrogen monoxide, in a space ratio of 1.8 / 1, as well as the continuous discharge of the non-reacted gases, whereby a working pressure of 2 ata is maintained in the apparatus.

If a concentration of 9.7 g hydroxylamine /! is reached, begins the continuous supply of sulfuric acid 25 # and the continuous discharge of the hydroxylamine sulfate solution, see above that the amount of the reaction mixture in the apparatus is kept uniform.

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The apparatus is left in operation for 20 days. In this An average hydroxylamine yield is obtained over a period of time of 90 # compared to the consumed ^ nitrogen monoxide and an average catalyst activity of 118.0 g NO / g Pt.h. The original activity of the catalytic converter experiences a reduction of only $ 35 during this time

After the catalyst has been separated by clarification from the mixture degreased from the apparatus, the catalyst according to Example 3 is reactivated and regenerated. The catalyst treated in this way, the activity of which has been brought back to the original ^value , is reintroduced into the apparatus, where the synthesis of the hydroxylamine begins and is then continued for 10 days. The subsequently separated catalyst shows an activity reduction of only 18 $.

As a result, two activations and two regenerations or applications are carried out successively with the same catalyst carried out during the synthesis, the synthesis periods being 7 days each. Each time the - "- activity of the catalyst and its hydroxylamine yield practically reproduced under the previous conditions.

Example 3

The spent catalyst obtained by decanting the acidic mixture removed from the hydroxylamine synthesis apparatus in Example 2 was separated with agitation

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Treated with 30 cm hydrogen peroxide $ 15, that afterwards was poured off. The catalyst was then intensively treated with 80 g of strongly acidic cation exchanger, Type I dejr jfirma Merck, mixed as this treatment for the A catalyst poisoned with metal ions is necessary.

After its separation from the cation exchanger, the Catalyst again an activation-regeneration treatment subjected, under the conditions of the original activation described in Example 1

The prepared and activated or reactivated and regenerated catalyst according to the invention has an increased original selectivity and activity, resulting in increased hydroxylamine yields - of over 95 # im Comparison to the nitric oxide consumed - leads »

In addition, the catalyst has an increased resistance against poisoning and a slow decrease in activity during the synthesis process on what a long-lasting Use - from 20 to 40 days - of the catalyst is permitted until it is activated and regenerated.

After a number of periods of work, it was discovered that the new catalyst after each reactivation and regeneration its activity and Bydroxylaminausbeute recovers again and that he same slowly sinking Kurv · maintain over time, as in his first B _en EXPLOITATION and thus a satisfactory reproduction - Has decorativeness. .

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When the invention is used, a catalyst is obtained for the synthesis of hydroxylamine by the hydrogenation of oil monoxide, etc., which include the following Offers advantages:

- increased selectivity and activity, increased resistance against poisoning and increased mechanical resistance, with a long service life;

- Through reactivation and regeneration, it can retain its original properties that were found in its preparation owned, recovered, with the same long re-use period

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Claims (2)

Fat withdrawal Platinum catalyst, possibly with additions of noble metals, stored on an inert carrier, intended for the production of hydroxylamine through the reduction of nitrogen monoxide, possibly of nitrogen oxide or trioxide, of nitric acid, nitrate ion or alkyl nitrites with hydrogen,
characterized by the following features: - to the hexachloroplatinum solution heated to boiling solution, a protective colloid such as gelatine, gluten or gum arabic and then an inert! preferably added graphite powder; The hexachloroplatinic acid in the paste obtained is ^{reduced at a temperature of -30 to +100 0 for a} minimum of 5 minutes with excess formaldehyde in a strongly alkaline medium, preferably in sodium hydroxide, whereupon the paste is reduced at a temperature of +10 Allowed to rest to + 10O ⁰ O for at least 15 minutes and then filtered, the catalyst being washed on the filter with water; - The washed and wet catalyst is activated by intensive contact with hydrogen in an acidic medium, preferably in dilute sulfuric acid, at a temperature of +20 to 105 ⁰ C, for a minimum of 5 minutes, in the presence of a small amount of ferric chloride « 2. platinum catalyst according to claim 1, characterized in that that in its preparation 0.05 to 5 g protective colloid and 1 to 300 g inert carrier, preferably graphite powder, can be used per 1 g of platinum. 3098U / 1Q41 222212 $. Platinum catalyst according to Claim 2, characterized in that that the amount of ferric chloride present during activation is 0.1 mg to 0.1 g per 1 g of platinum. 4-, platinum catalyst according to claim 1, characterized marked, that its reactivation and regeneration after its Use in the synthesis takes place in three stages - The catalyst on the carrier that is made of was separated from the acidic medium of the synthesis apparatus, becomes under agitation with a minimum of 0.5 cnr hydrogen peroxide $ 15> per gram, treated according to what that Hydrogen peroxide is poured off; - In the case of poisoning with metal ions, the catalyst on the 'friiger is intensive with cca 1.25 to 1.5 g of strongly acidic cation exchanger mixed per gram, from which it is subsequently separated; - on it the catalyst, for the purpose of reactivation and regeneration of a treatment by intensive bringing into contact with hydrogen in an acidic medium, preferably subjected to dilute sulfuric acid, like θ «in - ^ nsp, ruch 1 in - ^ with reference to the original Activation has been described. 3098U / KK1