NL7808206A - Iridium or iridium-ruthenium catalyst for hydrazine decomposition - comprises metal deposited on a carrier of specific pore vol. and surface area - Google Patents

Abstract

Catalyst for hydrazine decompsn. consists of a carrier having apore vol. >=0.1 cc./g. and a specific surface area 195 (Cp + 0.013 + 0.736 Vp), where Cp = carrier specific heat capacity at 25 degrees C. in cals./g./degrees C. and Vp = pore vol. in cc./g.; and Ir or Ir/Ru in an amt. 20-40 wt.% of catalyst. The metal is distributed through the pores in discrete particles sufficiently sepd. so as not to sinter or fuse at hydrazine decompsn. temp. For use as propellant system in rocket engines and gas generation chambers. Prod. has long effective life as a spontaneous catalyst and has good mechanical properties. A prepn. catalyst is capable of at least ten firings of 1 min. each from cold starts with 50 msec. delay and no initial overpressure. Crush strength is pref. 10-30 lbs.

Description

_ 1 __ H Oltói'cnv'itb Ctó> - '

Shell Oil Company at TTClJllllTgt'Un, Ver.St.v. America ! !

Process for the production of a catalyst.

The invention relates to the catalytic decomposition of hydrazine and relates to a new and more advantageous catalyst for promoting this decomposition. The invention also relates to an improved process for decomposing hydrazine and alkyl-5 substituted hydrazines using these new catalysts.

Hydrazine and lower alkyl-substituted hydrazines; are useful as disposable propellants for missiles and other projectiles. They decompose liberating heat and energy j j and can be used to generate gas for propulsion turbines | 10 as well as for operating control missiles for spacecraft and the like. The catalysts proposed so far for additives fits for promoting these decompositions have serious drawbacks. Platinum group metal catalysts are shown, for example, in U.S. Pat. Nos. 3,081,595 and 3,086,945. As previously suggested, these catalysts do not have all the required properties for successful use in propellants and gas generators. These requirements include the ability to initiate hydrazine decomposition at relatively low temperatures, for example, catalyst temperatures as high as 0 ° F with liquid hydrazine as high as 35 ° F. The catalyst must also be capable of at least ten firings per minute from the cold starts with less than 100 milliseconds delay and no significant overpressure at the start. The catalyst must further be resistant to temperatures of the order of 2000 ° F often encountered in the hydrazine decomposition. It must have adequate physical strength to withstand the treatment it undergoes in missile applications and must be effective after approximately one year in a space environment. These are essential requirements, not all of which are met by hydrazine decomposition catalysts prepared by the conventional methods.

Thus, an important object of the invention is to provide a catalyst which meets the above requirements! i in the decomposition of hydrazine and substituted hydrazines, hereinafter collectively referred to as hydrazines. Since hydrazine is a relatively stable chemical that can be stored in unventilated tanks! 5 for a long time, a very active catalyst is required for spontaneous 1 ignition at the high flow rates used in rocket engines. Since the temperature reached in the hydrazine decomposition j is high, with respect to normal catalytic processes, the catalyst must further have extraordinary stability for it to be able to restart many reams. The new catalysts have these requirements and have a long effective life as spontaneous catalysts for the decomposition of hydrazines, 1 meaning a spontaneous catalyst which will initiate and maintain the decomposition of the hydrazines when injected into! 15 the catalyst at the high speeds used in rocket engines and gas generator chambers. Still other advantages of the new catalysts will become apparent from the following description of the invention, in which some of the suitable catalysts are illustrated by representation; tative examples, which should not be construed as limiting the broader scheme of the invention.

It has been found that a special type of iridium metal catalyst deposited in a particular manner and in a critical high concentration on a special form support has a unique combination of properties, thereby fulfilling the appropriate requirements such as high activity and good stability. for an improved catalyst for decomposition of hydrazines. The new catalysts have an essential 2.

component a carrier with a specific specific gravity Ss m m / g given by the equation

S £ 195 (C + 0.013 + 0.736V) s P P

Wherein the specific heat capacity of the support is at about 25 ° C in calories per gram per ° C and the pore volume in cm3 / g. should not fall below 0.1. With a support of this kind there will not only be a suitable pore volume for applying the required amount of catalytic metal essential in the new catalysts without limitation of the pores such that the contact of hydrazines with the catalytic 7808206-3 metal is disrupted, but also there will be a desired mean temperature rise of at least 20 ° C of the heat of humidification of the porous catalyst volume when the pores are filled with liquid hydrazine at the time of starting. With the new catalysts prepared with supports of this kind, smooth spontaneous decomposition of hydrazines can be obtained even under unfavorable starting conditions.

Iridium has excellent advantages as the catalytic metal in the new catalysts, not only when used as the sole catalytic metal, but also in its particularly effective combinations with ruthenium. In these combinations, it is desirable to use about 30-80 atomic percent iridium in the ruthenium mixture. In order for the catalyst to have the desired high activity for spontaneous decomposition of hydrazines, it is essential that the iridium or mixture of iridium and ruthenium is present in an amount between 20-40% by weight of the final catalyst. This metal must be properly dispersed on the surface of the support if the catalyst is to have the stability that allows them to be used successfully for many consecutive starts. The metal or metals must be deposited as individual particles sufficiently separated from each other so that they do not sinter together or fuse together at the high temperatures achieved when decomposing hydrazines. Most desirably, the catalytic metal is uniformly distributed over the surface of the support into particles of about 10-100 in in diameter, which are separated from each other by an average of 20-200 8.. Most advantageously, the catalytic metal is present in particles of about 20 diameter diameter separated by about 50 van of each other. Separations are here understood to mean idealized distances j i measured along surfaces, and not directly the distances transverse j through pore walls.

The required catalytic metal distribution cannot be obtained by conventional catalyst fabrication methods.

It is necessary to use special methods which avoid the more or less uniform continuous coating of catalyst supports with metal, which would be encountered when using hitherto used methods for the production of hydrazine decomposition catalysts. It is necessary to diffuse the required amount of the indicated metal or mixture of 7808206-4 metals deep into the pores of the chosen support, and then build an increasingly heavier concentration of metal or metals outward from the deep interior until the concentration is very high in the external part of the carrier, in particular the peripheral skin portion of about 0.5 mm thickness of the carrier particles. The carrier which is suitably in the form of spheres or cylindrical pills, although other shapes or sizes are suitable, must not be so excessively loaded with metal in this "skin" portion that the penetration of the hydrazines to be decomposed exceeds necessary is disrupted.

It appears that most hydrazine decomposition takes place in the "skin" of the pill, ie, 0.1-0.5 mm thickness. The penetrated metal (or metals) is likely to serve two purposes: 1) it contributes to heat transfer through the pill, thereby reducing sudden thermal shock to the insulating support, and 2) continuing to catalyze the reaction after small amounts of the heavier metal-loaded exterior surface gradually erode with successive firings.

A particularly advantageous procedure for the production of the new catalysts uses repeated impregnations of the support with dilute solutions of an iridium salt with or without a ruthenium salt. With each impregnation, the metal-bearing ions are adsorbed on the support surface. When using a concentrated solution, the metal ions clump together in high concentrations and the resulting metal particles formed after decomposition and reduction are too large or too close together. When the dilute impregnation is merely followed by drying, seed crystals remain which cause the subsequent deposit to be deposited in the same places so that the same difficulties are encountered as when using solution. singings with too high a concentration. Therefore, it is necessary to use a treatment which changes the metal ions for the next impregnation with the dilute solution. The treatment should also be one that redissolves; prevents the deposition of salt deposited during the next impregnation and which promotes deposition at points on the support surface which have not previously been covered. In this multiple impregnation treatment it is advantageous to degass the carrier pills for the best final catalyst behavior by 7808206.

evacuation during some of the first impregnations, so that a better penetration of said solution is obtained.

Methods of achieving good metal distribution vary with the type of salt (or salts) used, the ion species present, and their distributions. These, in turn, are influenced by the nature of the solvent, the pH, salt concentration, and whether or not the saline solutions are "aged" before use. It is important to set conditions such that deep penetration of the pill is achieved at the beginning of the multiple impregnations, and that at these early stages a heavy internal coating which would interfere with the purpose of the invention does not is being formed.

In this multiple impregnation method, it is advantageous to use a solution of a metal salt for the impregnations, which can be decomposed by heating at a temperature below about 450 ° C and thus thermally decomposes the deposited salt after each impregnation. Suitable salts of iridium and ruthenium which can be used in this way include, for example, H2IrClg, H3IrCl6, HIrCl2 (OH) 2, IrCl3.H20, (NH4) 3IrCl6, (NH ^ IrClg (H20), / lr ( NH3) 4Cl2_7cl, / lr (NH3) 5 (H2) _7ci3, RuCl3, HClClg, (NH ^ RuClg and 20 [Ru (NH3) 4Cl2 / C1). Particularly useful results are obtained with the chlorides. Particularly useful for making the preferred iridium catalysts are hexachloroiridate (HglrClg), highly acidic solution of iridium trichloride such as IrCl3.3HCl or H3IrClg and iridium trichloride hydrate. these two metals on the carrier.

Solutions of the selected metal salt or salts in water alone, or aqueous or anhydrous alcohols such as, for example, the water-miscible alcohols methanol, ethanol, isopropanol and tertiary butanol, etc., are useful for the multiple impregnations. Generally, the solutions will contain salts in an amount of 0.02-1 gram atom of the required metal or metal mixture per liter, more advantageously about 0.1-0.6 gram atom per liter.

It has been found that iridium-containing catalysts with a more satisfactory overall behavior in the decomposition of hydrazines can be obtained if the alcoholic or aqueous solutions are aged before using them to impregnate the hydrazines. carrier. Not only are the solutions more homogeneous and therefore more suitable for uniform distribution of the catalyst metal throughout the support, but also the metal ions are often less strongly adsorbed from the aged solutions and are thus more able to penetrate the carrier pills more gradually and more uniformly. are deposited on the interior surface area through the pills. This is illustrated in tests conducted on the adsorption of aqueous iridium trichloride solutions containing about 0.02 g iridium per ml and 0.15 M relative to added HCl on an alumina support. Standing overnight provides a homogeneous solution. Particles of the alumina support with 156 m / g specific surface, a pore volume of 0.343 ml / g, a specific heat capacity at 20 ° C of 0.18 calories per gram per ° C and a size range of 100-200 mesh in a 1 mm ID column around a bed of! 8x9 inches deep over which the iridium chloride solution is poured. After passage of the aged solution, the alumina column is pale pale green over 1-1 / 16 inch, blue to pale green over the next, 2-3 / 4 inch, and then light yellow over the next 1/4 inch. This shows a rather weak adsorption and verifies the observation that rapid penetration of pills occurs with this type of said solution. More concentrated acid causes further spreading (tailing) of the color bands and more dilute acid causes less spreading. Catalytically, the best results are obtained with iridium trichloride alone with the dilute acid type solution. Absorption of IrClg from isopropyl alcohol solution on the same support shows such results. With a fresh solution, very strong adsorption occurs, with the iridium being essentially taken up at the head of the column, where a 0.5 inch dark band is formed. In aged solutions, only a trace of the dark band is present at the beginning of the column, and there is an extensive pale yellow colored band. The aged less strongly adsorbed ions are thus able to penetrate the aluminum oxide deeper. In the catalyst preparations this makes the metal more uniformly deposited in the internal pores.

35 The mechanism by which the more advantageous | 7 8 0 8 2 0 6 - 7 - catalysts are produced by using aged solutions, is not fully understood. In the case of the alcoholic solutions, there may be a reduction of catalyst metal ions to 3+ species such as Ir, or slow formation of a complex ion. Whatever the explanation of the improvement, it is usually desirable that the impregnation solutions used age for at least about 24 hours before application to the selected catalyst support. Fresh solutions can strongly deposit in a thick layer on the peripheral surface of the pills and the desired deep penetration in successive impregnations can thus not be achieved.

As previously explained, the pH of impregnation solution affects the deposition of the catalyst metal or metals on the surface of the support. Iridium salts such as, for example, iridium trichloride hydrate, hexachloriridate and iridium tetrachloride, an acidic pH in the range of about 0.5-4 is desirable, while a pH of about 2-3 is more advantageous in the solution. There is some increase in pH j of the residual aqueous hexachloroiridate solutions after the first subsequent impregnation of the alumina pills. Thus hydrogen ion as well as the iridium-containing ion species are adsorbed or react with the aluminum oxide. The equilibrium probably shifts to polymeric iridium species because of the decrease in hydrogen ion concentration. Gradual thickening of the solutions is observed with many impregnations. This again emphasizes the importance of deep penetration of the 25 pills at an early stage in the series of successive impregnations.

However, alkaline solutions can be used when using amine complexes of the metals. Thus, there are advantages in using iridium chloropentamine solutions for the multiple impregnation of the support, and in this case ammonia solutions having a pH of 8-10 are suitable.

In a successful method for carrying out the multiple impregnations, the selected catalyst support is immersed in the solution of the catalyst metal salt for a period of the order of about 10-60 minutes, until appropriate penetration of the support pores occurs had. The excess solution 78 0 8 2 0 6 1 - 8 is then allowed to drain in about 1-20 min. And the carrier is dried in the warm air stream preferably at about 120-150 ° C. The partially dried carrier particles are then heated gradually to about 250-450 ° C to complete the drying and effect partial decomposition of the catalyst metal salt. Usually about 10-60 minutes are sufficient to complete this operation, after which the support is cooled and the same series of treatments repeated until the required amount of catalyst salt is deposited to provide the necessary amount of catalyst metal in subsequent reduction, as mentioned above. Usually, at least seven separate impregnations will be required, and generally it will therefore be found to be more economical to operate with a single batch of impregnation solution which is reused until complete uptake by the wearer. However, it is also possible to continuously or intermittently add fresh catalyst metal salt solution to the solution applied to the support, or work in other ways to provide the desired catalyst metal deposition as described above. !

For the final reduction of the deposited decomposition products of the starting metal salt or salts, one can successfully use gaseous hydrogen at about 250-600 ° C. More generally, it is preferable to start with the reduction diluted with hydrogen increase nitrogen at about 300 ° C and the temperature and hydrogen concentration in the gases until the reduction is complete by heating at about 550 ° C for about 30 min with undiluted hydrogen.

The invention will now be illustrated with the following examples.

Example I

The preparation of an iridium-on-alumina catalyst by multiple impregnation of the support with an ammonia solution of Ircl 2 is carried out as follows:

An ammonia solution containing 9.2 g Ir per 100 ml is prepared by dissolving 25.0 g iridium trichloride with 54.6% iridium in 85 ml water by heating to 50 ° C, cooling and adding 60 ml 3 N ammonia.

j 35 The alumina support has a specific surface j i

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v 8 0 8 2 0 6 - 9 - 2 3 'of 156 m / g, a pore volume of 0.34 cm / g and is in the form of cylindrical pills of 1/8 inch diameter. The crush strength of individual pills, measured between flat plates, averages 17 pounds.

55 g of the carrier are soaked in the above solution for 10 min, dripped for 5 min, dried for 2-5 min with a hot air stream and then 15 min in a single layer in a 6 inch petri dish a heating plate, which is on high. In addition, the hot air stream of a 20 amp blower is sprayed onto the catalyst from a distance of 10 inches. The catalyst reaches a temperature of about 10 380 ° C and acid and ammonium chloride vapors are generated. The material is cooled and weighed.

The procedure just described is performed a total of six times to use all of the solution. The pills are then heated in; dry nitrogen at 300 ° C and reduce with a mixture of nitrogen and hydrogen (about 1:10) passed over the catalyst at 300 ° C for 0.5 hour, during which time much hydrogen chloride is released. The pills are cooled in nitrogen and then oxidized by exposure to air. The pills are then washed with three 100 ml portions of water each. A small amount of aluminum chloride (probably oxychloride) is removed, but no ammonium chloride is observed. The washing step may not be necessary, but in this case it is performed to remove any undecomposed ammonium chloride (nothing is observed). The pills are dried on the heating plate.

The pills are then treated for a second series of 25 with a freshly prepared ammonia iridium trichloride solution, as just described. This series also requires six treatments to remove all dissolving; adsorption. The reduction and washing is carried out as described above, and the final catalyst is then heated again to 300 ° C in nitrogen, followed by 0.5 hour in nitrogen / hydrogen at 300 ° C, and finally in hydrogen at 550 ° C for half an hour. .

This catalyst has an iridium content of 32% by weight. When tested for hydrazine decomposition in a 5 pound impact reactor with a cylinder of 1.04 inch internal diameter and 3.5 inch long at a feed temperature of 3-5 ° C and a feed rate of 13.6 g hydrazine per second, very good firing is observed. The ignition delay i _ _ ____________________________________j 7808206 _ 10 __ at 10 starting the reactor at 2-4 ° C is initially less than 25 milliseconds and increases to 90 milliseconds at the end of the sequence. Steadfast pressures of 185-192 psig are recorded and there are no overprints at the start. The ammonia decomposition is 57-62% and the catalyst loss as a fine dust is about 1% per minute firing.

Example II

The necessity to use more than seven impregnations in the preparation of the catalysts is shown by the following results obtained with iridium or alumina catalysts prepared by the following method:

Catalysts are prepared by soaking aluminum oxide pills of the type described in Example X in separate aqueous acid solutions of H 2 ClCl 3 for 1 hour. The pills are dripped, dried by a hot air stream, and then decomposed in air at 380 ° C for about 1 hour. The above procedure is repeated five times for Catalyst A using a solution with an iridium concentration of 21 g iridium per 100 ml, and 20 times for Catalyst B, the concentration of the impregnation solution being 6 g iridium per 100 ml. After the final impregnation and decomposition, each catalyst is reduced in a stream of hydrogen at 500-550 ° C. The results obtained are shown in the following Table A, the hydrazine decomposition test being carried out in the 5-pound impact reactor described in example. I.

Catalyst Table A A B

25 Number of impregnations 5 20

Iridium content of final catalyst,% 32 33

Hydrogen chemisorption, micromoles per gram 100 370

Catalyst activity fairly good

Ignition delay, milliseconds at shot 2Q number 10 in hydrazine decomposition 127 80

Catalyst Loss Rate, Percent Per Minute 2.4 0.8 The major difference in hydrogen chemisorption observed shows the large difference in the state of subdivision of the deposited metal. The smaller the size of the deposited metal particles, the larger the area will be suitable for hydrogen chemisorption and for 1 78 0 82 0 6 _ 11 ....

catalytic activity in the decomposition of hydrazines. The catalyst prepared by five impregnations has an iridium surface area of only about 1/4 that of the catalyst prepared by impregnation. rings, even though the total iridium content is about the same. The; Average metal particle diameter is about 17 lb in the catalyst prepared by 20 impregnations leading to very superior hydrazine decomposition.

Example III

The following data shows the excellent results obtained with a catalyst prepared from an aqueous hexachloroiridate solution, which has been aged overnight, before impregnating the same aluminum oxide support described in Example 1 with it. The alumina is baked at 700 ° C for 1 hour. The impregnation solution contains 0.29 grams of iridium per liter and 0.3 N of hydrochloric acid added. A total of 20 consecutive impregnations and decompositions are made, the impregnation time being varied from 5-10 minutes to 16 hours to achieve the desired metal salt penetration into the pills. The reduced catalyst contains 35% iridium metal.

In the 5-pound shock reactor motor described in Example I, the ignition delay at 10 starting the reactor at 2-4 ° C is initially less than 40 milliseconds, and increases to 80 milliseconds at the end of the sequence. Stable pressures of 185-189 psig are recorded and there are no overprints at the sturgeon. The catalyst loss as a fine material is only 0.5% per minute firing.

Example IV

The utility of other iridium salt solutions as impregnating agents to prepare the new catalysts is utilized. showed by the following results obtained with catalysts prepared in the general manner of Examples II and III using the same alumina support and solutions with 0.29 grams of iridium per liter. The number of successive impregnations ranges from 17-20 and the deposited salt is decomposed by heating after each impregnation. These catalysts contained 30-35 wt% iridium on the 1/8 inch pills used in a 45 cm bed for hydrazine decomposition at a hydrazine feed rate of 13.6 g / sec. The initial temperatures are 2-4 ° C before

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78 0 82 06 - 12 - both the feed and the catalyst and each firing lasts 60 sec.

TABLE B

Impregnation Solution Number of Ignition Catalyst Loss, Firing Delay% per Minute, Range (Milliseconds)

IrCl. in aqueous 0.02 N 6 25-30 1.0 HCl H ^ IrClg in isopropyl 7 20-30 0.9 alcohol 10 I ^ IrClg in aqueous HCl 10 20-45 0.3

IrClg in water 10 60-125 0.8 ^ IrClg in aqueous HCl 10 20-40 0.5

HjIrClg in aqueous HCl 10 20-80 0.5 15

Example V

The results obtained with catalysts prepared with mixtures of iridium and ruthenium metals applied to the alumina support of Example I in the same manner as in Examples II and 20 III were tested for hydrazine decomposition as described in Example I, as follows. In all cases, the catalyst contains 25-32% ruthenium plus iridium and more than 10 impregnations are used in its preparation

TABLE C

25 Impregnation Solution Ru / Ir Number Ignition Catalyst Firing Retardation Torque Ratio Groin (%

(millisec.) per min.) C

RuCl, in 10% H 2 O-90% IPAa) b) 117 H2lrèl 6 in 0.1 N HCl (ag.) ° 2 13 89 117 ° 6 "30 RuCl, in 10% HO-90% IPA - _ _ , c

IrCl3 in 0.3N2HCl (aq.) ° 3 8 2 ° "145 lfS

RuCi xn i °% H2O-90% IPA 0 21 5 20-179 2.8 H.IrCl- m 1.5 N HCl (aq.) Δ 6

RuCl- in 10% Η „Ο-90% IPA

H2IrClg in 0.15 N HCl (aq.) 0.21 3 80 1.535 0.21 2 125 1.9

Hgl-rClg-m 0-, 15-N HCl (aq.) ------------------------------—- 7808206 13 a) Isopropyl alcohol.

2 b) Prepared from alumina with a specific surface area of 80 m / g, a 3 pore volume of 0.29 cm / g and washing the final catalyst with 0.1 N hydrochloric acid.

5 c) Weight loss plus fine material, passing through a 10 mesh screen.

Example VI

A hydrazine decomposition catalyst is prepared, specially adapted for use in small control motors with only the low thrust (about 1 pound or less) required for position control, supplementary vernier thrust and the like, where periodically small amounts of hydrazine are to be decomposed by impregnation of 16-28 mesh grains of the alumina support of Example I with 31% iridium according to the method described in that example, using such a solution of ammonia iridium trichloride and seven impregnations averaging 15 min each.

This catalyst fires very well in a small reactor using 2.3 cm @ 3 catalyst. At about 3 ° C, at least six 9-second shots are successfully performed using 8 ml of hydrazine per shot and equally good results are obtained with repeated firing after the catalyst has been in the reactor for 6 weeks.

Although the use of alumina supports has been emphasized in the previous examples because of their superiority in the production of particularly active and stable catalysts, it will be understood that the invention is not limited thereto, as advantageously new catalysts for the decomposition of hydrazines can be prepared with other supports having specific surfaces conforming to the above formula and adequate pore volume. These include, for example, zirconium oxide, boron carbide, titanium nitride, zirconium nitride, boron nitride, zirconium carbide, carbon, zirconium boride, calcium zirconate and the like highly refractory supports. Among the aluminum oxides, the very stable forms derived from gels (such as gelatinous boehmite) are particularly advantageous.

The invention is also not limited to decomposition 7808206

Claims (7)

1. Hydrazine decomposition catalyst, characterized in that it consists essentially of a support with a pore volume of 3 2 at least 0.1 cm / g and a specific surface area, measured in m / g, equal to 195 (C ^ + 0.013 + 0.736 Vp) where C ^ is the specific heat capacity of the support at about 25 ° C in calories per gram per degree and V 3 ^ 10 the pore volume of the support in cm / g, and metal of the group consisting of iridium, and mixtures consisting of iridium and ruthenium deposited on said support in an amount of 20-40% by weight of the catalyst and divided by its pores into discrete particles sufficiently separated so that they do not sinter or melt together when the hydrizine decomposition temperature catalyst. ! Catalyst according to claim 1, characterized in that the support is aluminum oxide with a specific surface area of about 2 3 100-300 m / g, a pore volume of about 0.3-0.5 cm / g and a crushing strength. from about 10-30 pounds. Catalyst according to claim 2, characterized in that the metal on the alumina support consists only of iridium. Catalyst according to claim 3, characterized in that the metal on the alumina support is a mixture of about 30-80 atomic percent iridium with the remainder ruthenium. Process for preparing a catalyst for the spontaneous decomposition of hydrazine and capable of at least 10 firings of 1 minute each from the cold start with less than 50 milliseconds delay and no significant overpressure at the start, characterized in that one is in the pores of the support with a pore volume of at least 0.1 cm / g and a specific surface area measured in m / g equal to 195 (C + 0.013 + 0.736 V) in which C is the specific heat capacity P 3? 3? i of the support at about 25 ° C in calories per gram and V the pore volume 3 P] of the support in cm / g, brings a solution of a salt of the group consisting of iridium salts and mixtures of salts of iridium and ruthenium, which salt decomposes at a temperature below 450 ° C, which contains 7808206-15 said solution said metal in an amount of 0.02-0.6 gram atom of said metal per liter and with a pH of about 0.5-4, the solution-containing carrier d aims to deposit said salt in its pores, then the carrier is heated to decompose the deposited salt, impregnates the pores of the carrier again with said salt solution, the carrier dries again and the salt decomposes, the impregnation of the carrier with said salt is repeated, as is the drying of the re-impregnated support and the decomposition of the deposited salt at least seven times until the catalyst contains about 20-40% by weight of said metal, and the catalyst is heated in a stream of hydrogen gas at a temperature between 200 and 500 ° C to convert the decomposition products of the deposited salt into catalytically active metal. 6. Process according to claim 5, characterized in that the impregnations of the support are carried out with metal salt solution, which has been aged for at least 24 hours before immersing the support in it. 7. Process for preparing a catalyst for the spontaneous decomposition of hydrazine and capable of at least 10 firings of 1 minute each from the cold start, with less than 50 milliseconds delay and no significant overpressure at the start, characterized that aluminum oxide pills with a pore volume 3 of at least 0.1 cm / g and a specific surface area, measured in m / g, equal to 195 (C + 0.013 + 0.736 V), in which C is the specific heat-P PP capacity of the alumina at about 25 ° C in calories per 3 grams and V the pore volume of alumina in cm / g, immersed in an ammonia solution of an iridiura salt, which undergoes decomposition at a temperature below 450 ° C, which solution contains about 0.02-0.6 gram atom of iridium per liter and has an alkaline pH, the obtained aluminum oxide, containing said solution, dries to decompose the iridium salt in its pores, then the aluminum oxide is heated to 3 0 to decompose deposited iridium salt, perform the series of impregnation, drying and decomposition steps of the deposited iridium salt at least seven times, until the aluminum oxide pellets contain about 20-40% by weight iridium, after which the decomposed iridium salt is reduced to catalytically active metal by heating with hydrogen at about 200-500 ° C 35 f 7808206 / Ί W.