FI64750C - CATALYSIS FOR SOURCE ADJUSTMENT AV HYDRAZIN - Google Patents

Description

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Patent- och registerst / relsen 'AnsSkan utltgd och utUkrlftM published 30.09.83 (32) (33) (31) Requested ttuolkuu »- Begird priorltat (Tl) Shell Oil Company, One Shell Plaza, P.0. Box 2U63, Houston, Texas 77001, USA (72) Warren E. Armstrong, Cypress, Texas, Lloyd B. Ryland, El Cerrito, California, Hervey H. Voge, Sebastapol, California, USA (7 ^ +) Oy Kolster Ab (5M Catalyst for the decomposition of hydrazine - Catalyst for hydrogenation of hydrazine

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 the decomposition of hydrazine and alkyl-substituted hydrazines using these novel catalysts.

Hydrazine and lower alkyl substituted hydrazines are useful as propellant monofuels in rockets and other propulsion devices. They decompose, releasing heat and energy, and can be used to generate gas for use in turbines, as well as to direct position control jets, for example in rockets and spacecraft. The known catalysts proposed for use in accelerating this decomposition reaction have serious drawbacks. For example, platinum group metal catalysts have been disclosed in U.S. Patent Nos. 3,099,595 and 3,086,945. To date, it has not been possible to produce catalysts that meet all of these stringent requirements.

64750 which are set for their successful use in propellers and gas generators. These requirements include the ability to accelerate the decomposition of hydrazine at relatively low temperatures, for example catalyst temperatures as low as -17.8 ° C, and with liquid hydrazine at up to 1.7 ° C. The catalyst must also be capable of igniting at least ten one-minute ignitions, each of the cold outputs with a delay of less than 100 milliseconds without significant overpressure at the output. In addition, the catalyst should be able to withstand temperatures of the order of 1090 ° C, which often occur in the decomposition of hydrazine. It must have sufficient physical strength to withstand the stresses of rocket applications and should be operational after about a year in space. These are essential requirements that not all hydrazine decomposition catalysts prepared by conventional known methods meet.

The catalyst of the present invention meets the above requirements in the decomposition of hydrazine and substituted hydrazines, hereinafter collectively referred to as hydrazines. Because hydrazine is a relatively stable chemical that can be stored in closed containers for long periods of time, a highly active catalyst is needed to initiate and maintain a rapid reaction at the high flow rates used in rocket engines. In addition, because the temperature achieved in the decomposition of hydrazine is high compared to the temperature used in normal catalytic processes, the catalyst must be exceptionally stable if it is to be capable of many re-ignitions. The new catalysts meet these requirements and have long been useful as spontaneous catalysts in the decomposition of hydrazines, whereby a spontaneous catalyst refers to a catalyst that initiates and maintains the decomposition of hydrazines when injected into the catalyst at high speeds used in rocket engines and gas engines. Other advantages of the new catalysts will become apparent from the following description of the invention, in which some suitable catalysts are described by way of representative examples.

It has been found that an 8-type iridium metal catalyst catalyzed in a special manner and at a critical concentration of 3,64750 has a unique combination of properties that makes it meet the stringent requirements set out above for activity and good stability, so the new catalyst is very useful. in the breakdown of racins.

This new catalyst is characterized in that it consists essentially of a support with a pore volume of

O

at least 0,1 cm / g and a specific surface area of 195 (C + 0,013 +

2 P

0.736 V) m / g, where C is the specific heat capacities of the support-P ^ Q P

ti at about 25 ° C (kal / g / C) and V is the pore volume of the carrier 3 P

(cm / g} and a metal of iridium or a mixture of iridium and ruthenium, precipitated on this support in an amount of about 20 to 40% by weight of the catalyst and distributed in its pores as discrete particles spaced sufficiently apart so that they do not precipitate or fuse together when the catalyst is at the decomposition temperature of hydrazine.

The specific surface area of the carrier, Sg, is obtained from the equation S} 195 (C + 0.013 + 0.0736 Vp) m 2 / g where the pore volume V should be at least 0.1. This

P

the supported support has a sufficiently large pore volume to be able to receive the required amount of catalyst metal without the pores shrinking to such an extent as to interfere with hydrazine contact with the catalyst metal and in addition the desired temperature rise of at least 20 ° C under the wetting temperature are met with liquid hydrazine-1a at the time of initiation. The new catalyst, made with a support of this type, achieves uniform spontaneous decomposition of hydrazines under very unfavorable starting conditions.

Iridium has considerable advantages as a catalyst metal in these new catalysts, either as the sole catalyst metal or also in excellent effective combinations with ruthenium. These combinations preferably contain about 30-80 mole percent iridium and the rest rutBnium. In order for the catalyst to have the desired high activity for spontaneous decomposition of hydrazine, it is essential that the catalyst contain iridium or a mixture of iridium and ruthenium in an amount of about 20 to 40% by weight of the catalyst. This metal or alloy 64750 must be properly applied to the surface of the support in order for the catalyst to be stable, i.e., usable in many successive starts. The metal or alloy must be layered as separate particles sufficiently separated from each other so that they do not precipitate or fuse together at the high temperatures achieved in the decomposition of hydrazines. Most preferably, the catalyst stream 11i is evenly distributed over the entire surface of the support in the form of particles having a diameter of about 10 to 100 Å and spaced apart by an average of about 20 to 200 Å. Most preferably, the catalyst metal is present as particles of about 20 Å in diameter and spaced about 50 Å apart. Here, distances refer to imaginary distances measured along surfaces rather than direct distances cutting through pore walls.

The desired distribution of the catalyst metal is not achieved by conventional catalyst preparation methods. It is necessary to use a special process which avoids a more or less uniform continuous coating of the support with metal, which would be the case if previous processes for the preparation of hydrazine decomposition catalysts were used. It is necessary to diffuse the required amount of metal or mixture of metals deep into the pores of the carrier and then, as it moves outward from the deep interior, provide an increasing concentration of the metal or metals until the concentration is quite high in the outer portion of the carrier, especially the carrier and carrier grain of about 0.5 mm. in a thick surface layer. The carrier is preferably in the form of spheres or cylindrical pellets, but other forms are also suitable. However, the metal content of the surface layer of the catalyst must not be so high as to make it difficult for the hydrazines to be decomposed to penetrate. It seems likely that most of the degradation of hydrazine occurs in said surface layer, at a depth of about 0.1 to 0.5 mm from the surface of the granule. The infiltrated metal (or metals) presumably serves two purposes: (1) it assists in heat transfer through the pellet, thereby reducing the sudden heat shock to the poorly heat-conducting support, and (2) continues to catalyze the reaction after small amounts of heavily metal-loaded outer surface in successive ignitions.

The process according to the invention for preparing this new catalyst, which spontaneously decomposes hydrazine 5 64750 and is capable of igniting at least ten one minutes, each from a cold start, with a delay of less than 50 milliseconds and without significant overpressure, is characterized by a carrier volume of at least , 1 cm / g and a specific surface area of 195 (C + + 0.013 + 0.736 V g), an iridium salt or a mixture of iridium and ruthenium salts is introduced into the pores in the form of a solution which is decomposed at a temperature below 450 ° C and which contains a solution containing about 0.02 to 0.6 mol / l of metal, and the carrier containing the solution is dried. to retain the salt in its pores, then heating the carrier to decompose the doped salt, resaturating the pores of the carrier with this saline solution, drying the carrier again and a decomposing the salt, repeating the impregnation of the support with this salt, drying the resaturated support and decomposing the precipitated salt at least seven times until the catalyst contains n.

20 to about 40% by weight of this metal, and heating the catalyst in hydrogen gas at about 200-500 ° C to convert the decomposition products of the precipitated salt to the catalytically active metal.

At each impregnation, metal-containing ions are adsorbed on the surface of the support. If a concentrated solution is used, the metal ions will accumulate in large concentrations and the resulting metal particles formed after decomposition and reduction will be too large or too close to each other. If dilute impregnation is followed by drying alone, seed crystals remain, which cause the next precipitate to settle in the same places, so that the same difficulties are encountered as when using too concentrated solutions. Therefore, it is necessary to use a treatment that converts metal ions before the next impregnation with a dilute solution. The treatment must also be such as to prevent redissolution of the deposited salt during subsequent impregnation and to favor deposition at points on the surface of the carrier which have not previously been covered. In order to obtain the most active catalyst possible, in this multiple impregnation treatment, it is advantageous to remove gas from the carrier granules using a vacuum during which the impregnation is forgotten, whereby better penetration of the brine is achieved.

6,64750

Methods for achieving good metal distribution will vary depending on the type of metal salt (or salts) used, the type of ion present and their distribution, which in turn will be affected by the nature of the solvent, pH, salt concentration and whether or not the saline solutions are "aged" before use. it is important that the conditions are adjusted so as to achieve deep penetration at the beginning of the multi-stage impregnations and that no heavy outer coating is formed during these early stages, thus preventing deep penetration.

Suitable salts of iridium and ruthenium which can be used in this way are, for example, H2R1Cl2, H2O2Cl2, H2ClCl2CO2) (H2Cl3H2O), (NH4) 3IrCl2, (NH4) 2IrCl2H2O, /? / Γγ (ΝΗ3) 5 (Η20 17C13, RuCl3, HgRuClg, (NH4 gRuClg and / Ru (NH3) ^ 1 ^ Cl. Particularly advantageous results have been obtained with chlorides. Particularly useful for the preparation of preferred iridium catalysts are hexachloroiridate (H2IrCl , such as strongly acidic solutions of IrCl3 <3HCl or H3IrClg, as well as iridium trichloride hydrate Mixtures of ruthenium trichloride and said iridium salts provide quite advantageous impregnants for use in the preparation of new catalysts.

Aqueous solutions of salt (or salts) or aqueous or non-aqueous alcoholic solutions are used for impregnation. Suitable alcohols include water-miscible alcohols such as methanol, ethanol, isopropyl alcohol and tertiary butyl alcohol. As a general rule, solutions containing salts of about 0.02 to 0.6 moles of metal or alloy per liter are even more preferably about n.

0.1 to 0.6 moles per liter are suitable.

It has been found that iridium-containing catalysts with a more satisfactory overall performance in the decomposition of hydrazines are obtained if alcoholic or aqueous solutions are aged before being used to impregnate the support. Not only are the solutions more homogeneous and therefore more suitable for even distribution of the catalyst metal throughout the support, but the metal ions are also often less strongly adsorbed from the aged solutions and thus able to penetrate the support pores more gradually and deposit more evenly in the support. . This has been demonstrated by adsorption experiments performed with IrCl 2 solutions and the solutions contained about 0.02 g of iri-644750 dium / ml and about 0.15 moles of hydrogen chloride / l and the adsorbent was alumina. Standing overnight gave a homogeneous solution. Alumina support particles with a specific surface area of 156 rrr / g, a pore volume of 0.343 ml / g and a specific heat capacity at 20 ° C of 0.10 kal / g / ° C and a screen size of 100-200 mesh , was loaded onto a 1 mm diameter column to form a 20-23 cm long layer and the iridium chloride solution was poured onto the column. After passing through the aged solution, the alumina column was bright light green for 2.7 cm, blue to light green for the next 7 cm, and then bright yellow for the next 0.6 cm. This indicates a rather poor adsorption and confirms the observation that rapid penetration into the carrier granules occurs with this type of saline solution. The more concentrated acid caused further spreading of the ribbons (tail formation) and less spreading occurred in the more dilute acid solution. The best catalytic results were obtained with IrCl 2 alone with a dilute acid solution. Adsorption of f-IrClgCl from a solution of isopropyl alcohol on the same support gave similar results. A very strong adsorption takes place with the fresh solution, whereby iridium is mainly absorbed at the top of the column, where the dark quality formed a band of about 1.2 cm. The aged solutions gave a narrow dark line at the top of the column and had a broad light green band. Thus, aged, less strongly adsorbed ions were able to penetrate deeper into the alumina. In the preparation of the catalyst, this achieves a more uniform deposition of the metal in the inner pores.

The mechanism by which more preferred catalysts are prepared using aged solutions has not been fully solved. In the case of alcoholic solutions, it may be that there is a reduction of catalyst metal 3+ li ions to the Ir form, or that slow complex ion formation occurs. Whatever the explanation for the improvement, it has proved advantageous to stop the solutions used for impregnation at least n. 24 hours before being used to impregnate the catalyst support. Fresh solutions can be deposited as a strongly thick coating on the outermost surface layer of the granules and thus the desired deep penetration is not achieved immediately in subsequent impregnations.

8 64750

As noted above, the pH of the impregnation solution affects the deposition of the catalyst metal or metals on the surface of the support. When an iridium salt such as iridium trichloride hydrate, hexachloroiridate or iridium tetrachloride is used, the pH should be about 0.5 to 4, preferably about 2 to 3. There is some increase in the pH of the remaining aqueous hexachlor iridate solutions. after the first successive impregnation of the alumina pellets. Thus, hydrogen ions as well as the ionic species containing iridium are adsorbed on or reacted with alumina. The equilibrium is likely to shift towards polymeric iridium species due to a decrease in hydrogen ion content. Gradual thickening of the solutions has been observed after many impregnations. This again underscores the importance of the depth of penetration into the pellets at the beginning of the series of successive impregnations.

However, basic solutions can be used when amine complexes of metals are used. Thus, it is preferred to use solutions of iridium chloropentamine in the multiple impregnation of the carrier, and in this case ammonia-containing solutions having a pH between about 8 and 10 are suitable.

In one successful method of performing multiple impregnations, the support is immersed in a solution of the catalyst metal salt for about 10 to 60 minutes until sufficient penetration into the pores of the support has occurred. The excess solution is then drained off in about 1-20 minutes and the carrier is dried in a stream of warm air, preferably at about 120-150 ° C. The partially dried support is then slowly heated to about 250-450 ° C to complete the drying and to partially decompose the catalyst metal salt. Usually, about 10 to 60 minutes are sufficient to complete this delivery, after which the support is cooled and the same series of treatments is repeated until the required amount of catalyst salt has deposited to achieve the desired catalyst metal salt concentration. Usually at least seven separate impregnations are required and it is generally found to be more economical to operate with a single batch of impregnating solution that is reused until it is fully received by the carrier. However, it is also possible to continuously or intermittently add a fresh catalyst metal salt solution to the solution to be applied to the support or to operate in other ways to give the desired deposition of the catalyst metal described above.

For the final reduction of the layered decomposition products of the starting metal salt (or salts), gaseous hydrogen can be successfully used at about 250-600 ° C. More generally, it is preferred to begin the reduction with hydrogen diluted with hydrogen at about 300 ° C, and to increase the temperature and hydrogen content of the gases, whereby the reduction is completed by heating in undiluted hydrogen at about 350 ° C for about 30 minutes.

The following examples further illustrate methods for preparing these new catalysts and illustrate some of their advantages.

Example I

The preparation of the iridium / alumina catalyst by multiple impregnation of the support with an ammonia-containing solution of IrCl 2 was carried out as follows:

An ammonia-containing solution containing 9.2 g Ir / 100 ml was prepared by dissolving 25.0 g iridium trichloride containing 54.6% Ir in 85 ml by heating to 50 ° C, cooling and adding 60 ml of 3 N IMH.OH. The alumina support had a surface area of 156 m / g, a pore volume of 0.34 cm / g and was in the form of cylindrical granules with a diameter of 3.2 mm. The crushing strength of the individual granules, measured between the flat plates, averaged 7.7 kg. 55 g of carrier were dissolved in the previous solution for 10 minutes, drained for five minutes, pre-dried for 2-5 minutes with a stream of hot air and then dried for 15 minutes in one layer in a 15 cm petri dish on a hot plate at high temperature. In addition, hot air flow from the 20 A heat pump was directed to the catalyst at a distance of 25 cm. The catalyst reached a temperature of about 380 ° C and acid and ammonium chloride vapors were evolved. The material was cooled and weighed.

This procedure just described was performed a total of six times to consume all of the solution. The granules were then heated in dry nitrogen at 300 ° C and reduced (ca. 1:10) with a mixture which was passed to the catalyst at over 300 ° C for half an hour during which time a large amount of HCl was released. The granules were cooled in vacuo and then allowed to oxidize by exposing to air. The granules were then washed with three 100 ml portions of water. A small amount of 10,647,750 aluminum chloride (probably oxychloride) was removed, but no ammonium chloride was detected. The washing step may be unnecessary and was performed in this case to remove undegradable ammonium chloride (not observed). The granules were dried on a hot plate.

The granules were then treated in a second series with a freshly prepared ammonia-containing iridium trichloride solution as already described. This kit also requires six treatments to adsorb the entire solution. The reduction and washing were performed as described above, and the final catalyst was again heated to 300 ° C, followed by half an hour in a mixture of 300/10 h at 300 ° C and finally half an hour at 550 ° C. .

The iridium content of this catalyst was 32% by weight. In hydrazine decomposition tests in a 2.3 kg thrust reactor with an inner diameter of 2.6 cm and a length of 8.9 cm, a feed temperature of 3-5 ° C and a feed rate of 13.6 g hydrazine / s, a fairly good ignition was observed. The ignition delay at ten start-ups in the reactor at 2-4 ° C was initially less than 25 milliseconds, increasing to 90 milliseconds at the end of the series. Steady pressures of 1275-1324 kPa were recorded and no overpressures occurred during start-up. The decomposition of ammonia was 57-62% and the fine catalyst loss was about 1% / minute of ignition.

Example II

The need to use more than seven impregnations in the preparation of catalysts is demonstrated by the following results obtained with iridium / alumina catalysts prepared by the following method.

The catalysts were prepared by dissolving the image-type alumina granules in Example I in separate aqueous acidic solutions of H 2 O 2 Cl 2 for one hour. The granules were drained, dried with a stream of hot air and then decomposed in air at 380 ° C for about one hour. The above procedure was repeated five times for Catalyst A using a solution with an iridium content of 22 g Ir / 100 ml and 20 times for Catalyst B with a saturation solution concentration of 6 g Ir / 100 ml. After final impregnation and decomposition, each catalyst was reduced under a stream of hydrogen at 500-550 ° C. The results obtained are shown in the following table, in which the decomposition test for hydrazine referred to was carried out in a 2.3 kg thrust reactor described in Example I.

11 64750

catalyst A B

number of impregnations 5 20 iridium content of finished catalyst,% by weight 32 33 hydrogen chemisorption, micromoles / g ICO 370 catalyst activity moderate good ignition delay, milliseconds In shot no. 10 in hydrazine decomposition 127 60 number of catalyst,% / min. 2.4 0.8

The large observed difference in hydrogen chemisorption indicates a large difference in the state of underdistribution of the deposited metal. The smaller the size of the deposited metal particles, the larger the surface area available for hydrogen chemisorption and also for catalytic activity in the decomposition of hydrazines. The iridium surface area of the catalyst made with five impregnations was only about a quarter compared to the catalyst made with 20 impregnations, although the total iridium content was approximately the same. The average diameter of the metal particle was about 17 Åstroms in the catalyst made with 20 impregnations, resulting in a much better decomposition of hydrazine.

Example III

The following values show excellent results obtained with a catalyst prepared from an aqueous hexachloroiridate solution which was allowed to stand overnight before impregnation with the same alumina support described in Example I. The alumina had been treated in a muffle furnace at 700 ° C for one hour. The impregnation solution contained 0.29 moles of Ir / l and was about 0.3 N with respect to the hydrochloric acid added. A total of 20 consecutive impregnations and decompositions were performed with impregnation times ranging from 5-10 minutes to 16 hours to achieve the desired penetration of the metal salt into the granules. The reduced catalyst contained 35% iridium metal.

In the 2.3 kg thrust engine described in Example I, the ignition delay at 10 starts at 2-4 ° C was initially less than 40 milliseconds, increasing to 80 milliseconds at the end of the series. Steady substances of 1275-1303 kPa were recorded and there were no overpressures in the start-up pair. The fine catalyst loss was only 0.5% / minute of ignition.

12,64750

Example IV

The utility of other iridium salt solutions as impregnants in the preparation of these new catalysts is demonstrated by the following results obtained with catalysts prepared by the general method of Examples II and III using the same alumina support and solutions with 0.29 moles of Ir / l. The number of successive impregnations ranged from 17 to 20, and the deposited salt was decomposed by heating after each impregnation. The catalysts contained 30-35% by weight of iridium in 0.3 cm granules used in a 45 cm mattress for decomposing hydrazine at a hydrazine feed rate of 13.6 g / s. The outlet temperatures were 2-4 ° C for both feed and catalyst and the duration of each ignition was 60 seconds.

Impregnation solution Ignition Ignition Catalyst delay loss% / min range (milliseconds)

IrCl 2 in aqueous 0.02 N

In HCl 6 25-30 1.0 h ^ IrClg in isopropyl alcohol 7 20-30 0.9 h ^ IrClg in aqueous HCl 10 20-45 0.3

IrCl 2 in water 10 60-125 0.6 h ^ IrCl 2 in aqueous HCl 10 20-40 0.5 h ^ IrCl 2 in aqueous HCl 10 20-80 0.5

Example V

The results obtained with catalysts made with mixtures of iridium and ruthenium metals applied to the alumina support of Example I in the same general manner as in Examples II and III and tested for hydrazine decomposition as described in Example I are as follows. The catalysts in all cases contained 25-32% ruthenium + iridium and were prepared using more than 10 impregnations.

13,64750

Impregnation solution Ru / Ir- IgnitionK- Ignition- Catalyst No. with its loss, ratio · excitation% / min range (milliseconds)

RuClo 10% H 2 O-90% in IPAaT H 2 IrrCl 6 0.15 N ..

In HCl (aq.) 0.2DJ 13 89-117 0.6

RuCl 3 in 10% H 2 O-90% IPAr

IrCl 3 0.3 N HCl (a q.): S s a 0.3 0.3 20-145 1, 5

RuCl 3 10% H 2 O-90% in IPA H 2 IrCl 6 in 1.5 N HCl (aq.) 0.21 5 20-179 2.8

RuCl 3 in 10% H 2 O-90% in IPA H 2 IrrClg 0.15 N HOI (aq.) 0.21 3 80 1.5

RuCl 3 10% H 2 O-90% in IPA H 2 Ir 2 Cl in 0.15 N HCl (aq.) 0.21 2 125 1.9 a) isopropyl alcohol 2 b) made of alumina with a surface area of 80 m / g, 3 porosity 0.29 cm / g and the final catalyst washed with 0.1 N HCl c) weight loss + fines passing through a 10-mesh sieve

Example VI

The hydrazine decomposition catalyst, which is specially adapted for use in small control motors with only a small thrust (about 0.45 kg or less) and required for position control, replenishment-fine control operation, etc., where small amounts of hydrazine have to be intermittently decomposed, was prepared by impregnating 16- 28 mesh granules of the alumina support of Example I with 31% iridium according to the procedure described in Example I using a similar ammonia-containing iridium trichloride solution and using seven impregnations for an average duration of 15 minutes each.

the catalyst ignited very well in a small reactor using 2.3 cm 2 of catalyst. At about 3 ° C, at least six nine-second shots were successfully made using 8 ml of hydrazine per shot, and equally good results were obtained with repeated ignition of the catalyst to stand in the reactor for six weeks.

While the use of alumina supports has been highlighted in the above examples due to their superiority in the suppression of highly active and stable catalysts, it is to be understood that the invention is not limited thereto, as preferred novel catalysts for decomposing hydrazines can be prepared with other supports. the areas meet the requirements of the above formula and have a sufficient pore volume. These include, for example, zirconia, boron carbide, titanium nitride, zirconium nitride, boron nitride, zirconium carbide, carbon, zirconium boride, lithium zirconate, and the like, highly refractory carriers. Of the aluminas, highly stable, gel-derived forms (such as jelly boehmite) are particularly preferred.

The invention is also not limited to the decomposition of hydrazine, but can be used to decompose substituted hydrazines such as monomethylhydrazine, asymmetric dimethylhydrazine, etc. Thus, it is seen that the invention has many advantages and can be widely modified.

Claims (10)

1. Catalyst for the decomposition of hydrazine, characterized in that it consists mainly of a carrier material with a pore volume of at least 0.1 cm / g and a specific surface area of 195 (C + 0.013 + 0.736 V). g / g, where C is the specific surface P PDP heating capacity of the support material at about 25 C (cal / g / C) and 3 Vp is the pore volume of the support material (cm / g), and of a metal which is iridium or a mixture of iridium and ruthenium, stored on this support material in an amount between about 20-40% by weight of the catalyst and distributed in its pores as free-standing particles located at a sufficient distance from each other, so that they do not sintered or fused, where the catalyst is at the decomposition temperature of the hydrazine. 2. Catalyst according to claim 1, characterized in that the support material is an alumina having a surface area of about 100-300 m 2, pore volume of about 0.3 - about 0.5 cm / g and a crushing strength of approx. 4.5 - 14 kg. Catalyst according to claim 2, characterized in that the metal on the surface of the alumina support material is purely iridium. Catalyst according to claim 3, characterized in that the metal on the surface of the alumina support material is a mixture of about 30 -0 mole% iridium while the rest is ruthenium. A process for preparing a catalyst according to claims 1-4, which catalyst spontaneously decomposes hydrazine and is capable of at least ten ignitions of one minute, each from a kail start, with less than 50 milliseconds of delay and without significant overpressure at the start. , characterized in that in the pores of the support material having a pore volume of 3 at least 0.1 cm / g and a specific surface area of 195 (C + 0.013 + 2 + 0.736 Vp) rri / g, where Cp is the specific heat capacity of the carrier material at about 25 ° C (cal / g) and Vp is the pore volume of the carrier material (cm 2 / g), prior to an iridium salt or a mixture of iridium and ruthenium salts in the form of a solution which is decomposed at a temperature below 450 ° C and which solution contains the metal in an amount of about 0.02-0.6 mol / l, it dries the solution containing the carrier material to deposit the salt in its pores.