DE1816822C3 - Process for the production of a catalyst and its use for the conversion of hydrocarbons - Google Patents

Description

Zeolites already have a catalytic activity, for example for hydrocarbon conversions, however, they are generally made with one or more hydrogenating metals loaded, which give the finished catalyst the desired hydrogenation-dehydrogenation properties. Zeolites of the type are particularly suitable as catalysts or as support material for catalysts Faujasites, especially zeolite Y, and of the mordenite type.

In general, zeolites also contain alkali metals and / or alkaline earth metals, which, however, worsen the yield of the conversion products and also favor sintering of the zeolite material at high temperatures. Because of this, treated the zeolite material with a suitable cation exchange solution. In general if an aqueous solution of an acid or an ammonium compound is used for this ion exchange treatment, whereby the zeolite is then formed in the so-called hydrogen or ammonium form.

After the ion-exchange treatment, the zeolite material is removed from adhering exchange solution exempted a washing treatment and then dried and calcined, preferably in an oxidizing atmosphere, like air. If the catalyst is to be loaded with a metal having a hydrogenating effect the zeolite in the hydrogen form or ammonium form brought into contact with a solution which has a contains a suitable compound of the desired metal, and only then is the calcination carried out.

In some cases it has been found that calcining treatment of the ammonium treated Zeolite is detrimental to the catalyst activity of the finished catalyst. This catalyst deactivation originates from sintering of the hydrogenating metal and / or from destruction of the active sites of the zeolitic carrier material.

According to the invention, it is possible to overcome this deficiency, which occurs in particular in the case of catalysts which mii Ammonium compounds have been treated to eliminate.

The inventive method for producing a catalyst, wherein a support material from Zeolite type treated with ammonia and / or ammonium ions, with one or more hydrogenating agents acting metals and the catalyst in

ίο Presence of a containing or free oxygen is calcined from it existing gas at two different temperatures, is characterized by that the catalyst by competitive ion exchange by means of a solution, the ammonium ions and Contains noble metal ions in an ion ratio of at least 10: 1, in such an amount with Palladium and platinum are loaded so that the finished catalyst is 0.05 to 5 percent by weight of the noble metal contains that the catalyst with regulation of the gas flow at a first temperature of 200 to 400 ° C and then calcined to a final calcining temperature is heated from 400 to 900 ° C.

By means of the two-stage controlled calcination carried out according to the invention, any Avoid catalyst deactivation. The oxidative calcination according to the invention is based on the knowledge that ammonia is released from the zeolite material during the calcination treatment, immediately is oxidized to nitrogen and water according to the equation below:

2NHj IV2O2- + N ₂ + 3H ₂ O

The high rate of oxidation is based on the catalytic activity of what is present in the catalyst hydrogenating metal. This reaction is strongly exothermic and the heat released is 75 kcal / mole NH3. The released energy can locally overheat the material to be calcined lead, whereby the damage already described above are inflicted on the catalyst. Until now however, it was generally believed that the calcination of a metal-laden and ammonium ion containing zeolite material does not differ significantly from the calcination treatment of a non-ammonium ion loaded zeolite material differs

In view of the exothermic reaction explained above, however, it is of great importance that the Calcination temperature is strictly controlled.

For this reason, according to the invention, the zeolite material is first heated to a first calcination temperature heated in the range from 200 to 400 ° C, preferably very gradually. At this first one Calcination temperature is the temperature at which the decomposition of the zeolite in the Ammonium form uses, whereby gaseous ammonia is released, which then - like explained above - under the influence of the hydrogenating effect present in the catalyst material-

_b0 the metal is oxidized. The zeolite material is held at this first calcination temperature until practically all of the zeolite has been decomposed in the ammonium form. The temperature is then gradually increased to the second or final calcination temperature in the range from 400 to 900 ° C., preferably again very gradually.

The method according to the invention is special

suitable for the manufacture of catalysts on the Based on aluminosilicates with a molar silica-alumina ratio of at least 3: 1; these can through their composition the general molar formula below

Me ₂₁₁ P ■ AI2O3 - ArSiO ₂ yH ₂ O

be reproduced.

In this formula, Me denotes a metal with a valency n, in particular potassium, sodium or calcium knen, χ is a number in the range from 3.0 to 15.0 and y is a number in the range from 0 to 15. Particularly important representatives of this class of aluminosilicates are zeolite Y with a molar ratio of SiO ₂ : Al2O3 between 3: 1 and 6.5: 1 and mordenite with a molar ratio of SiO ₂ : Al2O3 of about 10: 1.

The two-stage controlled oxidative calcination according to the invention is of particular importance for the production of molded isomerization catalysts based on mordenite, platinum or palladium as hydrogenating metals and in which these metals in a high degree of dispersion are present. Such catalysts are because of their high activity for hydrocarbon conversion reactions particularly suitable The degree of metal dispersion can be determined by the atomic ratio H: Pt or H: Pd, which is determined by hydrogen emisorption. The highest activity will at atomic ratios H: Pt or H: Pd of 1: 1, with the noble metal on the carrier material has a maximum degree of dispersion.

The technique of hydrogen chemisorption is discussed in the following first references explained: "! .Catalysis" 1 (1962), p.336 and in "J.Catalysis" IO (1968), p.224.

In order to ensure a high degree of dispersion of the platinum or palladium on the catalyst, the metals concerned by means of a competitive ion exchange deposited on and / or in the zeolite material. This measure is particular then used with advantage when shaped zeolite catalysts, for example extrudates, pellets or tablets to be loaded with these metals. In the competition ion exchange it says Platinum or palladium in the cationic form with others present in the ion exchange solution Ions compete for exchangeable places on and / or in the zeolite material. in the In the context of the invention, the ammonium ion is used as a competitive ion

The platinum or palladium cations can be used in the form of a wide variety of salts or complexes will. Such cations are preferably used in the form of their amine complexes, which are derive from ammonia or N-substituted ammonia compounds, for example alkylamines, alkenyipolyamines and hydroxylamines. Examples of corresponding suitable compounds are

Tetramine platinum dichloride (Pt (NH 1J ₄ CI ₂ ),
Hexaminplatinteirach '^ - iH (Pt (NH 5JbCU) ₁
Di- (ethylenediamine) p.aur.uichlorid
(Pt (NH ₂ - C ₂ H ₄ - NH ₂ J ₂ Cl ₂ ) and
Tetramine palladium dichloride (Pd (NH ₃ J ₄ CI ₂ ).

The platinum or palladium compound must be used in such amounts that the finished catalyst Contains 0.05 to 5.0 percent by weight of the precious metal

Those used in the ion exchange treatment

60 ammonium ions can be derived from ammonium salts of mineral acids or lower organic acids with up to 10 carbon atoms in the molecule. For example, such salts are ammonium nitrate, ammonium sulfate, ammonium chloride, ammonium iormat, ammonium acetate and ammonium citrate. However, preference is given to using salts which leave no acid group in the calcined catalyst. The competitive ion should be present in a large excess compared to the noble metal, so that the latter is deposited in a finely divided and homogeneous form on and / or in the zeolite material. Therefore, the ion ratio between the competitive ion and the noble metal ion is at least 10: 1, and preferably this ratio is in the range of about 100: 1 and above. Very good results have been achieved with solutions which contain the competitive ion in concentrations of at least 0.7 molar and preferably 1 to 2 molar.

In order to achieve high atomic ratios H: Pt or H: Pd, it has proven to be very advantageous that To neutralize zeolite material before loading with the hydrogenating metal, preferably up to a pH 7. This neutralization treatment offers particular advantages when it comes to shaped Zeolite material of the zeolite type Y and the mordenite is. For such a neutralization that will Zeolite material brought into contact with ammonia or an organic nitrogen base, preferably along with ammonium ions.

Ammonia and / or ammonium ions can also be used to reduce the content of alkali metal or alkaline earth metal in the zeolite material by ion exchange. For the purposes of the present invention, a zeolite material treated with ammonia and / or ammonium compounds is referred to as NH ₄ zeolite. The temperature at which the decomposition of such an NH ₄ zeolite begins depends on the type of the particular zeolite material used. The decomposition of the NH ₄ -zeolite Y begins for example at about 250 ⁰ C while a NH ₄ mordenite only begins at about 350 ° C to decompose.

The final calcination temperature is more or less the same for all types of zeolite that are calcined. However, it must be taken into account that metal hydrosilicates of the zeolite type generally become thermally unstable or are deactivated above a certain maximum temperature, the value of the maximum temperature being different for each zeolite type. For example, mordenite is thermally inactivated at temperatures above 650 ° C, while Y zeolite is thermally unstable at temperatures above 85O ⁰ C. In the process according to the invention, zeolites containing platinum and palladium are preferably subjected to the final calcination at a temperature in the range from 475 to 650.degree. Calcination temperatures of about 500 to 600 ° C. are particularly preferred.

Generally, the zeolite material is at the first calcination temperature for at least 15 minutes held.

During the preferably gradual heating of the zeolite material to the first Calcination temperature, air can be used as the oxygen-containing gas. At the beginning, the Oxygen content of the gas be 20 percent by volume or even more. As soon as the first calcination

temperature is reached, the oxygen supply is reduced per unit of time, if necessary the entire Oxygen supply and inert gas is fed in at the same time or the gas supply is increased overall. These Gas flows are regulated in the required manner, depending on the heat released at the first calcination temperature. Because you can use platinum or palladium-containing zeolites calcined, it is essential to keep the oxygen content as high as possible in order to be highly active catalysts receive. As soon as the temperature is increased to the final calcination temperature, preferably again gradually, the oxygen content of the gas is no longer critical. The calcination in the final stage can be carried out in be carried out in the usual manner in a stream of air or oxygen.

The controlled calcination is preferably carried out in such a way that the material temperature during the first calcination stage is practically constant. This means, however, that that of the incoming The amount of heat dissipated from gases should practically correspond to the heat generated.

No specific values can be given for the flow velocities of the gas, as they depend on many factors, such as the amount of material to be calcined, whether this Material spread in thin layer or not, of the type of furnace used, of the construction material of the furnace and the like. However, Ks is lür that It is not difficult for a person skilled in the art to regulate the gas flow in an appropriate manner.

The invention is explained in more detail with reference to the drawings (FIGS. 1 to 6). ^{The temperature in 0} ° C. is given on the abscissa in each case. The figures show records of the heat released which have been obtained by means of thermogravimetric analysis and thermal differential analysis on microsamples of zeolite material treated with ammonium compounds. These recordings clearly show the occurrence of an exothermic reaction, the maximum of the curve generated by the reaction determining the first calcination temperature of the process according to the invention.

Fig. 1 shows a block diagram by means of a thermogravimetric balance when heating NH4-mordenite is obtained in air. The weight losses at each temperature level are plotted of 40 ° C. The decomposition of the N m zeolite begins slowly below 600 ° C.

Fig.2 shows a block diagram that occurs during heating a mordenite impregnated with an ammoniacal platinum chloride solution in air by means of a thermogravimetric Libra is obtained. The decomposition of the platinum-containing NHU zeolite takes place between 360 and 520 ° C.

F i g. 3 shows the recording of the heat of reaction obtained when an NH-t-mordenite impregnated with an ammoniacal solution of platinum chloride is heated in air. A device for differential thermal analysis was used for the recording (reference connection: Λ-ΑΙ2Ο3). The exothermic maximum at 36O ⁰ C, and the first calcination temperature is preferably selected to be somewhat below this maximum

F i g. FIG. 4 shows a differential thermal analysis record of the same material as FIG. 3, but using NH ₄ mordenite as a reference component.

F i g. 5 shows the thermal behavior of an ammoniacal Platinum chloride solution of impregnated NhU zeolite Y for differential thermal analysis in air (connection: «-AI2O3). The decomposition takes place in Range between 240 and 470 ° C and it becomes a wider exothermic effect observed starting at around 250 ° C and extending to around 450 ° C.

F i g. 6 shows the recording of the thermal behavior of the material analyzed in FIG. 5 and explains this thermal release of ammonia in a nitrogen atmosphere. The maximum amount of ammonia is released at around 300 ° C. A total of about 3.96 percent by weight of ammonia is formed.

A comparison of Fig.2 and i> shows that when calcining a noble metal halligen NFU zeolite Y in air, the exothermic oxidation of ammonia is more difficult to control than in the case of a corresponding metal-laden NH ^ -Mordenite, because the rapid thermal decomposition of the first mentioned Material takes place at a much lower temperature.

As can be seen from the foregoing, the recordings were obtained on microsamples. For the industrial implementation of the method according to the invention, for example, the following can be used Duty cycle can be used:

(a) Heating the ammonium treated and noble metal loaded zeolite material inside a period of at least 1 hour, preferably from 3 to 6 hours, to the first Calcination temperature;

(b) Maintaining the zeolite material at that temperature regulate simultaneously for at least 15 minutes, preferably for at least 1 hour the oxygen supply during process steps (a) and (b);

(c) increasing the temperature in the course of at least 1 hour, preferably from 2 to 5 hours, on the final calcination temperature and

(d) calcining the material at this final temperature for at least 1 hour, preferably for 2 to 6 hours.

The zeolite-based catalysts prepared according to the invention can be used for a wide variety of hydrocarbon conversion processes be used, for example, for hydrogenative cleavage, polymerization, alkylation and dealkylation, for reforming and isomerization. Precious metal loaded catalysts based on mordenite are however, particularly suitable for the isomerization of lower hydrocarbons in the presence of Hydrogen, in particular, can riiii such Noble metal catalyst any aliphatic hydrocarbon with at least 4 carbon atoms in the Molecule can be converted into a corresponding, more highly branched hydrocarbon. The concerned Catalysts are therefore particularly suitable for the isomerization of hydrocarbons with 5 to 10 Carbon atoms and mixtures of such hydrocarbons. Usually used as a starting material Hydrocarbons or hydrocarbon mixtures boiling only below about 600 ° C used Very suitable hydrocarbon starting mixtures are the directly distilled fractions obtained from petroleum, the hydrocarbons containing 4 to 7 carbon atoms.

If hydrogen is also used to prevent deactivation of the catalyst, it is

lü

possible to treat hydrocarbon mixtures containing olefinic hydrocarbons, since the Isomerization the unsaturated compounds are converted into the corresponding isoparaffins. In The alkyl and alkenyl groups of alkyl and alkenyl aromatics can also be used in a corresponding manner isomerized and, if desired, hydrogenated. It is also possible to use naphthenic compounds to isomerize.

example 1

1 kg of NH4 mordenite is produced by first treating synthetic powdery mordenite with a two-molar aqueous hydrochloric acid solution, then washing the mordenite with deionized water and subjecting it to an ion exchange treatment using a one-molar aqueous ammonium nitrate solution. The ΝΗ, ι-mordenite obtained in this way is then treated in ion exchange with an ammoniacal platinum chloride solution which contains 1.44 g of Pt / liter (2.5 liters of solution per kg of mordenite, calculated on a dry basis). The suspension is ^{heated to 50 °} C. and kept at this temperature for several hours with stirring. The supernatant liquid is then decanted off and the zeolite material is washed with one liter of deionized water per kg of mordenite. The mordenite loaded with platinum is dried ^{in flowing air at 120 °} C. in a tube furnace equipped with several thermocouples. After a drying time of 4 hours, the temperature is increased to 350 ° C (temperature of the material) and the temperature is kept constant by increasing the gas flow through the oven by introducing nitrogen in each case when the temperature of the sample recorded by the thermocouples increases rapidly begins. After the temperature has still maintained an additional hour at 350 ⁰ C, it is increased within 4 hours at 51O ⁰ C and then held for 3 hours at this value. The finished catalyst shows a high degree of isomerization accessibility with n-pentane. The H: Pt atomic ratio determined by hydrogen chemisorption is 0.6.

Example 2

45

Using commercially available mordenite extrudates having a particle size of 1.587 mm, a molded mordenite catalyst is produced.

1 kg Mordenitextrudate having a sodium content of 7.0 wt .-% Na 2 O is first heated together with 10 liters of an aqueous two-molar hydrochloric acid solution to about 100 ⁰ C is then washed with deionized water and still heated three times each for one hour at about 100 ° C with an aqueous one molar ammonium nitrate solution, each time a fresh solution in an amount of 1 liter of solution per 100 g of mordenite is used. The loaded in this manner with ammonium ion exchange in the mordenite is dried washed with deionized water at 12O ⁰ C and ω

The dried shaped catalyst particles are loaded with platinum through competitive ion exchange. For this purpose, 1 kg of the dried mordenite is suspended at room temperature in a two-molar ammonium nitrate solution (0.25 liter of solution per 100 g of mordenite). This suspension is neutralized to a pH of 7 using 28% strength by weight aqueous ammonia. By adding more ammonia, the pH of the slurry is repeatedly adjusted to this value until it remains constant for at least an hour. Then an aqueous solution of Pt (NHs ^ Ck is added to the slurry (23 g Pt / liter solution). The platinum is used in an excess of 30% compared to the theoretically required amount, which has a platinum content of 0.4 wt .-%, to the finished catalyst. during the addition of the platinum-containing solution, the slurry is well stirred and the stirring is still a further 8 hours continuously, while the temperature is maintained at 50 ⁰ C. the supernatant liquid is decanted and the molded Catalyst particles are washed with deionized water and then dried at 120 ° C.

The mordenite particles loaded with platinum are calcined in flowing air. The mordenite is spread in a thin layer of 4 mm in an oven equipped with several thermocouples. The temperature is slowly increased to 350 ^° C. (measured in the material) and then kept at this value as precisely as possible by increasing the air flow every time the thermocouples indicate a rapid increase in the material temperature. The temperature is kept at 350 ^° C. for one hour and then increased to 510 ^° C. over the course of 4 hours, after which it is kept at this value for three hours. The finished catalyst has an Na2O content of 0.15% by weight, of platinum of 0.36% by weight and has an H: Pt atomic ratio of 0.8, determined by hydrogen chemisorption.

Example 3

Starting from a powdery mordenite, a catalyst based on mordenite in the form of formed particles.

350 g of a commercially available mordenite powder with an average particle size of 5 Microns are mixed with 3.5 liters of a two molar aqueous hydrochloric acid solution for one hour cooked. The powder is then filtered off and washed with one liter of deionized water. Then the mordenite is treated in a percolation column with an aqueous one molar Ammonium nitrate solution converted to the ammonium form at room temperature. The treatment will be like this continued until the drain is free of sodium ions. The thus obtained NH4 mordenite with a Sodium content of 0.04 wt .-% Na2O is then added Washed deionized water and slurried again in deionized water (0.5 liters of water 100 g powder each). To this slurry with a pH of about 4, 26.9 ml of a aqueous solution of Pt (NHiJiCb added. This Treatment solution contains 29 mg platinum per ml. The slurry is stirred for at least half an hour, then filter it and dry the mordenite powder at 120 ° C.

The mordenite powder is ground with 85 g of ammonium bentonite in a ball mill and then 525 g of water are added to the dry powder mixture. Milling is continued until an extrudable paste is obtained. This paste is extruded to give extrudates of 3 mm which are dried at 12O ⁰ C. The ammonium bentonite is obtained as follows:

Commercially available bentonite is boiled twice

030 249/12

for one hour each in an aqueous two-molar ammonium nitrate solution (one liter of solution per 100 g Bentonite). The NH4 bentonite obtained in this way is then filtered off, washed with deionized water and treated with Dried at 120 ° C.

The dried extrudates are calcined in the manner explained in Example 2. The finished catalyst contains 0.4 wt .-% platinum and has an atomic H: Pt ratio of 0.6. It contains about 20% by weight of the bentonite binder.

The activity of the catalyst obtained in this way is tested in a standard experiment using the isomerization of n-pentane under the following conditions: temperature 250 ° C., pressure 30 kg / cm ² , space velocity 1 g n-pentane per g catalyst per hour, molar ratio H. ₂ : n-pentane 2.5. Before carrying out the experiment, the catalyst is reduced in a hydrogen atmosphere at 500 ° C.

The results obtained are summarized in the table below:

Table 1

Composition of the reaction product

after 2h after 9h

<C ₅ , wt% 2.0 2.2

iC ₅ , wt% 65.1 62.5

nC ₅ , wt% 32.9 35.3

Example 4

This example illustrates the influence of the controlled calcination according to the invention on the isomerization activity of the catalyst.

According to Example 2, samples of a non-calcined, platinum-loaded, molded mordenite catalyst are used made containing 0.4 wt .-% platinum. This shaped catalyst is after calcined by various methods. In experiments Nos. 1 and 2, the shaped catalyst is used in the usual way Calcined manner, with the zeolite material slowly heated to a calcination temperature of about 500 ° C will. In experiments no. 3 and 4, a step-shaped calcination is carried out, but in the

ίο the first calcination ^{temperature of 35O 0} C there is no strict temperature control. In experiment no. 5, the exothermic heating effect is controlled by feeding in nitrogen as in Example 1. A muffle furnace is used in experiments 1-4.

on the other hand, in experiment 5 a tube furnace, as is usually used for catalyst regeneration. The effect of the calcination measures on the H: Pt atomic ratio is shown below Table II.

The shaped catalyst particles thus calcined are used for isomerization of n-hexane used. To do this, the catalysts are first carefully treated with hydrogen in the following manner reduced:

Before being introduced into the reactor, the extrudates are allowed to become loaded with moisture in equilibrium with the water content of the air. Then the catalyst using 560 normal liters of hydrogen per liter of catalyst per hour at an absolute pressure of 30 kg / cm ² and a temperature between 250 and 35O ⁰ C for one hour is reduced. Following this reduction, the temperature to 24O ⁰ C is lowered, and then is passed η-hexane in the reactor at an hourly space velocity of 2 g η-hexane per g catalyst per hour and using a molar ratio hydrogen: η-hexane of 2.5. Under these conditions, the n-hexane conversion shown in the table below is achieved.

Table II

attempt
No.

Calcination treatment

Atom-
relationship
H: Pt conversion
of n-hexane
Wt% 0.12
0.16 29.5
44.0 0.29 49.8 0.44 52.2 0.52 54.3

3 hours at 500 C, 3 hours at 500 C; thick material layer (250 g) moist sample introduced into the oven at 500 C, 3 hours at 500 C (5 g)
2 hours at 350 C, 2 sid. at 350 C, 1 hour at 500 C ",

1 hour at 500 C; thick material layer (250 g)

2 hours aur350 C, 2 hours at 350 C, 1 hour at 500 C, 1.5 hours at 500 C; thin layer of material (250 g)

2 hours at 350 C ^- , 1.5 hours at 350 C, 2 hours at 500 C, 5 hours at 500 C; Temperature rise during calcination treatment at 350 C * suppressed by introducing nitrogen (200 g)

The above data confirm that the calcination treatment of the present invention is too highly active Isomerization leads, as can be seen from the Atomic ratio H: Pt and obtained from the percentage conversion.

Example 5

This example explains the influence of the procedure according to the invention on the production of with Noble metal loaded zeolite catalysts, both with regard to the metal distribution and the

Isomerization activity of the finished catalyst.

According to Example 2, 3 mm mordenite extrudates with a low sodium content are prepared. These are loaded with tetramine-platinum compounds using various methods. After a final calcination carried out for 3 hours at 500 ^° C., the catalysts obtained in this way are tested for their isomerization activity in a microflow reactor. The catalysts are tested

reduced beforehand by means of hydrogen at 250 ^° C. and a pressure of 30 kg / cm ^2.

N-Pentane is used as the feed material for the isomerization. The isomerization is carried out under the following conditions: temperature 250 ° C., pressure 30 kg / cm ² , molar ratio of hydrogen to n-pentane 2.5: 1, hourly space velocity 1 g of n-pentane per g of catalyst per hour. The results obtained are summarized in the table below.

Table III

Pt-switch of the loading of the shaped catalyst Catalyst

Weight K

Pt distribution i-pentane (visually) content of Reaction product Wt% inhomogeneous 44-46 inhomogeneous 40-41 almost homogeneous 55

Ion exchange with Pt (NH ₃ ) ₄ (NO3) ₂ Impregnation with Pt (NH ₃ J ₄ CI ₂ Ion exchange with a solution of Pt (NH ₃ ) ₄ (NO ₃ ) ₂ containing 1 mol of NH ₄ NO ₃ per liter ( See Example 2) Ion exchange with a solution of Pt (NH ₃ I ₄ Cl ₂ , which contains 2 mol NH ₄ NO ₃ per liter (see Example 2) homogeneously

58

Example 6

This example illustrates the influence of an excessively high final calcination temperature on the platinum dispersion and the activity of the finished catalyst.

According to Example 3, mordenite powder is pretreated with an aqueous hydrochloric acid solution and an aqueous ammonium nitrate solution, as a result of which the sodium content is reduced to 0.04% by weight Na ₂ O. The mordenite powder modified in this way is loaded with 0.36% by weight of platinum according to the competitive ion exchange method according to Example 2. The material is then subjected to a controlled calcination at a first calcination temperature of 350 ° C and a Schlußkalzinierung at a temperature of 51O ⁰ C. The catalyst obtained in this way has an atomic H: Pt ratio of 0.94. Part of the catalyst is carefully reduced with hydrogen ^{at 250 °} C. and a pressure of 30 kg / cm ^2. After the reduction treatment, n-pentane is fed in and isomerized at the same temperature and the same pressure, an hourly space velocity of 1 g of n-pentane per g of catalyst per hour being used. The molar ratio of hydrogen to starting material is 2 ^>. Thereby 68% is converted into isopentane

Another part of the calcined catalyst is calcined again for 3 hours at 650 "C The atomic ratio H: Pt of the re-calcined catalyst is 0.08. The catalyst is in the reduced form used for isomerization under the conditions mentioned above and the Conversion of n-pentane to isopentane is only 40%.

Example 7

Starting from a commercially available powdery zeolite Y, a catalyst is on the Base made of faujasite in the form of particles

By treatment of a commercially available powdered zeolite Y, which is that by heating the powder several times with fresh two molar ammonium nitrate solution, the powder is then calcined (temperature 550 ⁰ C) and heating the calcined material with a fresh molar ammonium nitrate solution once again be 0, 76 kg of a decationized zeolite Y with a low alkali metal _{content was obtained (0.3% by weight Na 2} O, water content about 21.0% by weight). The catalyst is slurried in 1.5 liters of a 2 molar ammonium nitrate solution. The pH of the solution is adjusted to about 7 by adding concentrated 28% strength by weight ammonia, and more ammonia solution is added until the pH is one hour remains constant at this value. 130 ml of a _{solution containing Pd (NH 3} ) 4 (NO ₃ ) 3 and containing 30 mg of palladium per ml are then added to this slurry. The solution is added with stirring. The mixture is stirred for a further 16 hours at a temperature of

so 50 ⁰ C, then filtered off the solid material, washed with deionized water and dried at 120 ° C.

The zeolite Y loaded with palladium is mixed with 985 g of ammonium bentonite in a ball mill for 30 minutes (Water content about 8.6% by weight) mixed. The bentonite in the ammonium form is according to FIG Procedure of Example 3 has been obtained. Then 1.6 liters of deionized water are added and by further grinding it becomes a paste that can be pressed out. This paste becomes particles of 3 mm pressed which are dried at 120 ° C.

The pressed-out particles are calcined at a first calcination temperature of 250 ⁰ C to control the temperature of the material to be treated and treated at 500 ⁰ C, finally for 3 hours The final catalyst has a Na ₂ O-GeIIaIt of 02 wt .-% and a palladium content of from 0 , 2% by weight. It contains about 56.4% by weight of the bentonite binder.

In addition 6 sheets of drawings

Claims (2)

Patent claims: 1. A process for producing a catalyst, wherein a support material of the zeolite type is treated with ammonia and / or ammonium ions, loaded with one or more hydrogenating metals and the catalyst is calcined in the presence of a gas containing or consisting of free oxygen at two different temperatures is, characterized in that the catalyst by competitive ion exchange using a solution containing ammonium ions and noble metal ions in an ion ratio of at least 10: 1, is loaded with palladium and platinum in such an amount that the finished catalyst 0.05 to 5 percent by weight of the Noble metal contains that the catalyst is calcined with regulation of the gas flow at a first temperature of 200 to 400 ⁰ C and then heated to a final calcination temperature of 400 to 900 ° C. 2. Use of a catalyst prepared according to claim 1 for the conversion of hydrocarbons.