Composition based on zirconium oxide, titanium oxide or mixed zirconium and titanium oxide, applied on aluminium oxide or aluminium oxyhydroxide carrier, methods of its obtaining and its application as catalyst. RU patent 2476381.

FIELD: chemistry.

SUBSTANCE: invention relates to field of chemistry, in particular, to catalytic compositions, applied as catalyst. Claimed are catalytic composition, methods of its application and catalytic system. Catalytic system, which contains at least one oxide on carrier, selected from zirconium oxide, titanium oxide or mixed zirconium and titanium oxide, applied on aluminium oxide or aluminium oxyhydroxide carrier, and which has after burning at 900°C for 4 hours size of particles of oxide on carrier not larger than 10 nm, if oxide on carrier is obtained on zirconium oxide base or not larger than 15 nm, if oxide on carrier is obtained on the base of titanium oxide or mixed zirconium and titanium oxide. Catalytic system contains claimed catalytic composition.

EFFECT: ensuring high catalytic properties of catalyst work at high and room temperature with preservation of dispersity of active phase on carrier.

15 cl, 1 dwg, 7 ex

The present invention relates to a composition based on zirconium oxide, titanium oxide or a mixed oxide of zirconium and titanium supported on a carrier of alumina or oxyhydroxide aluminum, the means of its production and its use as a catalyst.

Catalysts often consist of an active phase which is a phase with desired catalytic properties, and the media, which caused the aforementioned active phase. For catalyst efficiency is important that the active phase was more finely dispersed on the carrier, so that this active phase was on a carrier in the form of finely dispersed, not subjected to aggregation of particles. In addition, since the catalysts are often exposed to high temperatures, it is also necessary to finely dispersed state of the active phase was preserved even at this temperature. In other words, should not occur sintering of particles.

The aim of the present invention is to develop catalysts that meet these requirements.

For such purpose, the composition according to the invention contains at least one oxide on the carrier, selected from among zirconium oxide, titanium oxide or a mixed oxide of zirconium and titanium supported on a carrier of alumina or oxigeno the sid aluminum, and is characterized by the fact that after firing at 900°C for 4 hours, the oxide on the carrier is in the form of particles deposited on said media, which are:

not more than 10 nm, if the oxide on the carrier obtained on the basis of zirconium oxide;

not more than 15 nm, if the oxide on the carrier based on titanium oxide or a mixed oxide of zirconium and titanium.

Other distinctive features, details and advantages of the present invention become clearer upon reading the following further description and from the drawing, and:

the drawing is a RD-the diffraction pattern of the product according to the invention and in accordance with the prior art.

Under rare earth element understand the elements from the group consisting of yttrium and elements of the periodic system having an atomic number lying in the range from 57 to 71 inclusive.

In the continuation of the present description under understand specific surface the specific surface according to BET, defined by nitrogen adsorption in accordance with ASTM D 3663-78 established on the basis of the method of brunauer, Emmett and teller described in The Journal of the American Chemical Society, 60, 309 (1938).

In addition, calcination at a given temperature for a specified time, unless the opposite, firing in the air after establishing a constant temperature in the course of the specified time.

For the continuation of the present description should also clarify that, if you don't specify the opposite of all the above intervals or limits of values boundary values are included in their composition, therefore, the interval or range of values defined in a similar way, cover all values not smaller lower bound and/or large upper bound.

The composition according to the invention contains an oxide on a carrier in the form of particles of nanometric size, the mentioned particles supported on a carrier.

This oxide on the media first of all can be a zirconium oxide without additives, i.e. a simple oxide in the form of ZrO₂.

The oxide on the carrier can also be a doped zirconium oxide, i.e. it can consist of zirconium oxide and at least one oxide of another element M selected from among praseodymium, lanthanum, neodymium and yttrium. In this case, the zirconium oxide ZrO₂is a major or dominant component, whereas the element or elements M is the rest of oxide on the carrier.

The content of the element M is not more than 50 wt.%, moreover, the zirconium oxide is at least 50 wt.% oxide on the carrier. This value content, expressed as weight of oxide of the element M or set of elements of M with respect to the weight of all the hydroxy is and on the media (Zirconia and oxide(s) element(s) M). The value of the content of the element M may vary in a wide interval, in particular, it may be in the range from 5 to 40%, preferably from 10% to 40%. This is most preferably may be in the range from 10% to 30%.

The oxide on the carrier can also be a titanium oxide TiO₂.

In addition, the oxide on the carrier may be a mixed oxide of zirconium and titanium. The mixed oxide in this case it is necessary to understand the solid solution of oxides of titanium and zirconium in the form of pure crystallographic phase with the structure ZrTiO₄. In this case, the analysis of the product using the method of x-ray diffraction (RD) does not allow to establish the existence of different patterns, in addition to ZrTiO₄. This structure corresponds to the card 34-415 joint Committee on powder diffraction standards (JCPDS). Such solid solution is generally in a state in which the proportion of titanium oxide relative to the total weight of the mixed oxide may be in the range from 30 wt.% up to 40 wt.%.

Here it should be noted that the composition may contain several types of oxides on the carrier, i.e. to simultaneously contain particles of zirconium oxide, particles of titanium oxide and particles of mixed oxide, and each of the said oxides at the same time is in the form of particles having the above RA the measures.

The oxide on the carrier is in crystalline form.

It should be noted that the oxide particles on the carrier can either be solid or may be in the form of units.

The values of the dimensions given in this description represent the average values of the dimensions specified way RD. The value measured by the method of EP corresponds to the size of the domain of coherence calculated from the width of the three most intense diffraction beams in the spatial group x, y, z using the model of Debye-sherrer.

Above were given the particle size of the oxide on the carrier depending on the type of oxide on the carrier and calcining the composition. As mentioned above, particles are deposited on the media. Under this it should be understood that the oxide particles on the media are predominantly located on the surface of said carrier, and it is assumed that the particles can be inside the pores of the support, however, remain on the surface of the above-mentioned pores.

In addition, the oxide on the carrier completely has the form of particles on the carrier in the above sense, i.e. this means that in the compositions according to the invention, there is no part of the above-mentioned oxide, which simply would be in the form of a mixture of this part of the oxide with the rest of the song; the rest of the song, in this case, the content of the Ala would the media and the rest of the oxide in the deposited media form.

The size of the oxide particles on the media after firing at 900°C for 4 hours is preferably not more than 9 nm, if the oxide on the carrier is an oxide of zirconium, possibly doped, and not more than 12 nm, if the oxide on the carrier is a titanium oxide or a mixed oxide of zirconium and titanium.

After calcination for 4 hours at 1000°C, the particle size of the oxide on the carrier is not more than 20 nm, preferably not more than 17 nm, if the oxide on the carrier is an oxide of zirconium, possibly doped, and not more than 30 nm, if the oxide on the carrier is a titanium oxide or a mixed oxide of zirconium and titanium.

The minimum particle size are not critical and can be very low. Solely as an example, you can specify that the size of the particles may be at least 4 nm, in particular at least 6 nm, if the oxide on the carrier is an oxide of zirconium, possibly doped, and at least 8 nm, in particular at least 10 nm, if the oxide on the carrier is a titanium oxide or a mixed oxide of zirconium and titanium. These minimum values are also given for the compositions subjected to calcination at 900°C for 4 hours.

The advantage of the compositions according to the invention compared with the known compositions of the same type is possible the TB incorporating a larger amount of oxide on the carrier in the absence of it causes sintering of the particles of oxide when exposed to the composition of the high temperature.

The content of the oxide on the carrier in the composition according to the invention is usually not more than 50 wt.% from the whole composition. In particular, it can be no more than 30%.

The minimum content of the oxide on the media has such a value, which is the specialist in the art it is known that, since it is possible to achieve a sufficient catalytic activity, and is determined depending on the desired performance of the composition. Just as an example, you can specify that the mentioned minimum value is usually at least 3 wt.%, more preferably at least 4 wt.%. It can also be at least 10%, more preferably at least 15%, even more preferably at least 20%.

The oxide content in the media, in particular, may lie in the range from 10% to 50%, more preferably from 10% to 30%. It may also lie in the range from 15% to 30% or from 20% to 30%.

The media in the composition according to the invention first of all can be a carrier based on alumina. These media preferably should have a high and stable, i.e. keeping a high enough value even after exposure to high temperature, the specific surface.

In the present invention may use any type of oxide of al is MINIA, can have a value of specific surface area, sufficient for use in catalysis. Thus, in particular, it is possible to use aluminum oxide having a specific surface area equal to at least 150 m²/g, preferably at least 200 m²/g, even more preferably at least 300 m²/year

Mention can be made of aluminum oxide obtained by the rapid dehydration of at least one kind of aluminum hydroxide, including bayerite, hydrargillite or gibbsite, nordstrandite, and/or at least one type of oxyhydroxide aluminum, including boehmite, pseudoboehmite and the Diaspora.

The media can also be a carrier-based oxyhydroxide aluminum aforementioned species also possess proper, i.e. corresponding said above in respect of the aluminum oxide, the value of the specific surface.

According to the private variant of implementation of the present invention, use is stable and/or doped aluminum oxide or oxyhydroxide aluminum. As a stabilizing and/or deruosi elements can be called rare earth elements, barium, strontium and silicon. As the rare earth elements in particular can be called cerium, praseodymium, neodymium, lanthanum or a mixture of lanthanum and neodymium. These elements can be used separately and in combination. As preferred combinations can be called La-Ba, Ba-Pr, La-Pr-Ba and La-Pr.

It should be noted that in the continuation of the present description, the terms "stable", "doped", "stabilizing" or "deruosi" should be understood as non-restrictive; deruosi element, therefore, can be considered as a stabilizing factor, and Vice versa.

Preparation of stable and/or doped aluminum oxide or oxyhydroxide aluminium carried out by a commonly known method, in particular by impregnation of alumina or oxyhydroxide aluminum salt solutions, including nitrates, the above-mentioned stabilizing and/or deruosi elements, as well as through co-drying the precursor of aluminium oxide and salts of the above elements and subsequent firing.

You can also mention another way of obtaining a stabilized alumina, which alumina powder obtained by the rapid dehydration of the hydroxide or oxyhydroxide aluminum is subjected to technological operations of aging in the presence of a stabilizing agent consisting of compounds of lanthanum and possibly compounds of neodymium, and this connection, in particular, can be a salt. Aging may be carried out by suspension of alumina in water with posledujushhim to the temperature lying in the interval, for example, from 70 to 110°C. After aging the alumina is subjected to heat treatment.

Another way to obtain is similar to the processing with the use of barium or strontium.

The content of stabilizing and/or operauser element, expressed as the ratio of the mass of the stabilizing oxide and/or operauser element to the mass of the stabilized and/or doped aluminum oxide or oxyhydroxide aluminum is typically in the range from 1.5% to 35%, or from 1.5% to 25%, or from 1.5% to 15%. This value content, in particular, may be in the range from 2.5% to 20%, more preferably from 2.5 to 11% or from 5% to 20%.

According to the private variant implementation, the stabilizing element is a barium and/or strontium, and its contents, expressed as the ratio of the mass of the oxide stabilizing element to the mass of the stabilized aluminum oxide or stabilized oxyhydroxide aluminum is not more than 10%.

Finally, the composition of the invention can have a high specific surface area by BET, is able to make after firing at 900°C for 4 hours, at least 80 m²/g, more preferably at least 120 m²/g, even more preferably at least 150 m²/g After calcination for 4 hours at 1000°C. such compositions can have from the part surface, equal to at least 50 m²/g, more preferably at least 80 m²/g, even more preferably at least 100 m²/year

The composition of the invention can be prepared in various ways, which are described next.

A. the First method of preparation of the compositions according to the invention

The first method includes the following steps:

- cast colloidal dispersions of compounds of zirconium and/or titanium, and may compound of the element M in contact with the connection of aluminium;

- spray drying thus obtained mixture;

- firing the dried product obtained in this way.

Thus, the first step of this method consists in casting aluminum compounds into contact with a dispersion with the formation of a mixture on the basis of a colloidal dispersion of zirconium compounds, colloidal dispersion of titanium compounds or colloidal dispersion containing a compound of zirconium, and a compound of titanium, depending on the nature of the oxide on the carrier in the composition that you want to cook. In the case of the preparation of compositions in which the oxide on the carrier is a mixture of zirconium oxide and at least one oxide of another element M, the mixture also contains a colloidal dispersion of the oxide of this element. You can also use one number is odnoy dispersion, the basis of colloids in which is a mixed oxide of zirconium and of an element M of Course, this description applies to the case where the oxide on the carrier contains several elements of M; in this case, it is clear that this can be applied several dispersions of the various elements of M, or perhaps only one colloidal dispersion containing all of the elements of M. For brevity, in the remainder of this description reference will be made to only one dispersion of one element M, however, the present description should be understood as applicable to the above case.

Under the colloidal dispersion understand any system that consists of finely dispersed solid particles of colloidal dimensions, i.e. dimensions lying in the range from approximately 1 nm to approximately 100 nm (the size measured by the method of quasielastic light scattering), on the basis of zirconium compounds, titanium and/or of the element M, and a similar connection is typically an oxide and/or hydroxide, in the form of a stable suspension in an aqueous liquid phase, and the particles, in addition, can also contain residual amounts associated with or adsorbed ions, including, for example, the nitrate, acetate-, floridino or ammonium ions. It should be noted that in such a colloidal dispersion of zirconium, titanium or element M can either be entirely in the form of the of olloidal, either simultaneously be in the form of ions and colloids.

The mixture is produced from the dispersion and aluminum compounds. Such connection of the aluminum can represent the actual media, in particular, in the form of aluminum oxide or oxyhydroxide aluminum, and the above-mentioned aluminum oxide or oxyhydroxide aluminum in this case should be considered as relating to the above types and how, in particular, can be stabilized and/or doped as described above; a compound of aluminum may also be a precursor of aluminum oxide, i.e. a compound capable of forming the aluminum oxide after firing. You can use dried, i.e. having a loss on ignition of not more than 50%, in particular more than 25%of its predecessors. Thus, the above mentioned compound may be selected from hydroxides or oxyhydroxides aluminum. So, they may be aluminum hydroxide, including bayerite, hydro-argillite or gibbsite, nordstrandite, or oxyhydroxide aluminum, including boehmite, pseudoboehmite and diasporas. The connection of the aluminum can be in the form of a suspension, in particular, aqueous suspension.

The mixture is produced in the aqueous phase, usually water, for example, distilled or permuteran water.

The second step of the method is a step of drying.

Drying spend p is the spray.

Under spray drying understand the drying by spraying the mixture in a hot atmosphere (spray-drying). Spraying can be carried out using any well-known type of spray, for example, spray shower head type sprayer or otherwise. It is also possible to implement a so-called turbine nozzles. Information about the various methods of spraying, suitable for use in the present method, it is possible, in particular, be found in the seminal work of masters, entitled "Spray drying" (K. Masters, Spray-drying, 2^nded., 1976, George Godwin, London).

The temperature at the outlet of the atomizer may lie in the range of, for example, from 80°C to 150°C.

The last step of the method is the step of firing.

Such firing provides the possibility of increasing the crystallinity of the product on the media; the firing method can also be adjusted and/or selected depending on the temperature further application, intended for the composition according to the invention, while taking into account the fact that the specific surface of the product is lower the higher the applied temperature firing. Such firing is usually carried out in air, but, of course, does not rule out the firing, for example, in an inert gas or in a controlled (oxidizing or reducing) atmosphere.

In practice temperaturehigh usually limit the range of values, lying between 500°C and 800°C, preferably between 600°C and 700°C. the firing Time pick a known manner; it may vary, for example, from 30 minutes to 4 hours, but usually the lower, the higher the temperature.

B. the Second method of preparation of the compositions according to the invention

The composition of the invention can also be prepared by the second method described below.

This method contains the following steps:

- obtaining a liquid mixture containing a salt of zirconium or titanium, and may element M, and the connection of aluminium;

- heating the thus obtained mixture to a temperature equal to at least 100°C;

the extract thus obtained precipitate;

- firing is referred to sludge.

In the first stage, as in the previous method, apply compound of aluminum, and above for the first stage regarding this connection is applicable to this case. However, in the second method it is mixed with the salt of zirconium and/or titanium salt and, in the case of compositions in which the oxide on the carrier obtained on the basis of zirconium oxide and an oxide of another element M, with a salt of the element M, the Mixing is carried out in aqueous phase, usually in water. It should be noted that in the case of the use of aluminum compounds in suspension this original suspension, if necessary, may be acidified.

Salt can be in the gap among nitrates, sulfates, acetates and chlorides.

Thus, in the examples, in particular, to mention sulfate Zirconia, nitrate Zirconia and chloride Zirconia. You can also use oxychloride or oxysulfate titanium.

The next step of the method is a step of heating the thus obtained liquid mixture.

The temperature to which the heated liquid mixture is at least 100°C., more preferably at least 130°C. It can also be in the range from 100°C. to 150°C. the heating Operation can be carried out by placing the liquid mixture in a closed shell (closed-type reactor of the autoclave). As an illustration, you can specify that in the above temperature conditions in the aquatic environment pressure in the closed reactor can vary over a range of values from more than 1 bar (10⁵PA) and 165 bar (1,65^.10⁷PA), preferably between 5 bar (5^.10⁵PA) and 165 bar (1,65^.10⁷PA). At temperatures close to 100°C, it is also possible implementation of heating in an open reactor.

Heating can be carried out either in air or in an atmosphere of inert gas, preferably nitrogen.

Heating time may vary within wide limits, components, for example, from 1 to 48 hours, preferably from 2 to 24 hours. The temperature increase perform at a speed that is not critical is eskay; so, given the reaction temperature can be achieved by heating the liquid mixture, for example, during the time of 30 minutes to 4 hours, and mentioned only that values are given only as an example.

After the step of heating the extracted solid residue, which may be separated from its containing environment using any classical method of separation of solid and liquid phases, including, for example, filtration, decantation, drying or centrifuging.

The extracted product can then be subjected to the procedures of washing, which in this case is carried out by means of water or perhaps a basic solution such as ammonia solution or an acidic solution, such as, for example, nitric acid.

In accordance with the private embodiment of the present invention, the method includes the step of aging.

Mentioned aging usually carried out in a suspension obtained after repeated cultivation of sediment in the water, particularly after washing. Aging is carried out by re-heating of the suspension. The temperature to which heat the suspension is at least 40°C., more preferably at least 60°C., even more preferably at least 100°C. Typically, this temperature is not more than 200°C., more preferably not more than 150°C. With the food support at a constant temperature over time, usually at least 30 minutes, more preferably at least 1 hour. Aging may be carried out at atmospheric pressure or, possibly, at higher pressure.

The last step of annealing the second method can be carried out in the same way as in the first method, therefore, discussed above, regarding the firing is applicable to this case.

In the case of the preparation of compositions containing as a carrier of aluminum oxide or oxyhydroxide aluminum, stable and/or doped with a stabilizing and/or deruosi element selected from among rare earth elements, barium and strontium, you can use two other methods (third and fourth), which are described next.

C. a Third method of preparation of the compositions according to the invention

The third method includes the following steps:

- a₁) obtaining a liquid mixture containing a colloidal dispersion of oxide on the media and, perhaps, the oxide of the element M, the connection of aluminum and a compound of the stabilizing element;

- b₁) cast just mentioned mixture in contact with the ground with obtaining a suspension containing the precipitate;

in₁) drying of the suspension obtained in this way;

- g₁) firing thus obtained dried product.

Mix on stage and₁exercise is in the aqueous phase, usually in the water.

As oxide on the media used any colloidal dispersion of the above described type.

The connection of the stabilizing element, in particular, can be a salt, including the nitrate, acetate, chloride, sulphate, in the form of a solution.

The connection of aluminium applies to the types described above for the first method.

The second step of the method consists in bringing the mixture obtained in stage a₁in contact with the ground.

As a basis you can use products like, for example, hydroxides, carbonates or basic carbonates. Mention can be made of hydroxides of alkaline or alkaline earth metals, secondary, tertiary or Quaternary amines. However, amines and ammonia may be preferred for the reason that they reduce the risk of contamination of the cations of the alkaline or alkaline earth metals. You can also mention urea.

The bringing into contact can be carried out in a liquid medium in any order.

The addition of a base, in particular, is carried out until reaching the pH of the reaction medium, is equal to at least 7.

Making contact with the ground is a consequence of the sediment suspended in the liquid reaction medium.

According to one of embodiments of this method, if necessary, it may contain additional e the AP, single action on the suspension obtained at the previous stage b₁by aging. Aging is carried out by heating the suspension to a temperature component of at least 60°C., more preferably at least 80°C. This temperature is usually not more than 200°C., more preferably not more than 150°C. Environment support at a constant temperature for a period of time, usually at least 30 minutes, more preferably at least 1 hour. Aging may be carried out at atmospheric pressure or, possibly, at higher pressure.

At the end of stage b₁or perhaps stage of aging, if applicable, carry out the above steps in₁and g₁. These two stages are similar to the last two steps of the first method according to the invention, and all that has been said above on this occasion, similarly applicable to the stages in₁and g₁. However, it should be noted that drying can be carried out by a method other than sputtering, for example, in an oven.

The third way you can apply a variant implementation. This variant is that at the end of stage b₁or perhaps stage of aging, if applicable, the precipitate was separated from the suspension, washed and re-dispersed in water with the aim of obtaining in the second dispersion. Last dispersion is then subjected to a drying phase in₁.

, The Fourth method of producing compositions according to the invention

The fourth method of preparation includes the following steps:

- a₂) obtaining a liquid mixture containing a colloidal dispersion of oxide on the media and, perhaps, the oxide of the element M, and the connection of aluminium;

- b₂) cast just mentioned mixture in contact with the ground with obtaining a suspension containing the precipitate;

in₂) adding to the suspension thus obtained, the compounds of the stabilizing element;

- g₂) drying of the suspension obtained in the previous step;

- d₂) firing thus obtained dried product.

This method differs from the third way that the connection stabilizing element type on a separate stage at the end of stage b₂or perhaps stage of aging, which in this case may be performed after step b₂. As a consequence, all that was said in the description of the third method, similarly applicable in this case. In particular, the connection of the stabilizing element refers to the same types as for the above-described method. In addition, it is also possible to apply a variant described above for the third method, according to which at the end of stage b₂or possibly what about, stage of aging, if applicable, the precipitate was separated from the suspension, washed and re-dispersed in water to obtain a second dispersion. In this case, the connection of the stabilizing element is added to the second suspension.

Described only the fourth method is particularly suitable for the case where the stabilizing element is a barium or strontium.

D. the Fifth method of preparation of the compositions according to the invention

The fifth method comprises the following steps:

- obtaining a liquid mixture containing compound of aluminum and at least one salt of zirconium or titanium, and may element M;

- bringing the just-mentioned mixture in contact with the base with the purpose of obtaining a precipitate;

- removing the precipitate, thus obtained;

- firing above the sediment.

The first phase of the fifth method is similar to the first stage of the second method, so the above on this issue is applicable to this case.

The second step consists in obtaining a precipitate from the reaction mixture obtained in the previous step, to the base. Mentioned above in relation to stage b₁the third method is similarly applicable in this case.

The addition of a base, in particular, is carried out until reaching the pH of the reaction medium, is equal to at least 7.

The extraction and burning of sludge spend ways, similar to the one described above, in particular, for the second method.

The composition of the invention, such as those described above or the like obtained by the methods described above have the form of powders, however, they may be molded in order to give them the form of granules, beads, cylinders or honeycombs of various sizes.

The composition of the invention can be used as catalysts. Therefore, the present invention also relates to catalytic systems containing compositions according to the invention. Such systems contain coating (primer, washable coating (wash coat)with catalytic properties derived from such compositions, and a binder is applied onto a substrate type, for example, metal or ceramic monolithic. The coating is obtained by mixing the composition with a binder so as to form a suspension, which can then be applied to the substrate.

Such catalytic systems, in particular, the composition according to the invention can find a lot of different ways. They are particularly well adapted to the conditions and, therefore, Aleutskaya for the catalysis of various reactions including, for example, dehydration, hydrocortisone, gidrogenizirovanii, desulfuromonas, hydrodesulfurised, dehydrohalogenation, reforming, steam reforming, cracking, hydrocracking, hydrogenation, dehydrogenation, isomerization, disproportionation, oxychlorination process, dehydrocyclization hydrocarbons or other organic compounds, oxidation reactions and/or recovery, the Claus reaction, treatment of exhaust gases of internal combustion engines, including afterburning of exhaust gases, in particular, in the three-component converters, demetilirovania, mahanirvana, shift-conversion, catalytic oxidation of soot generated by internal combustion engines, including diesel or petrol engines mode low loads. Finally, the catalytic system and the composition of the invention can find application as catalysts for selective reduction of NOx by reduction reaction of NOx in any reductant hydrocarbon nature, as well as ammonia or urea, and, in the latter case, as catalysts for hydrolysis or decomposition of urea to ammonia (method SCR).

In the above-mentioned applications in catalysis compositions according to the invention can be used in combination with precious metals, as well as with the transitional meta is Lamy in the form of oxides, sulphides or in another form, and thereby play the role of the media data for metals. The nature of these metals and methods of their introduction in the compositions carriers are well known to the person skilled in the art. For example, the metals may include gold, silver, platinum, rhodium, palladium or iridium, molybdenum, tungsten, Nickel, cobalt, manganese or vanadium; they can be used separately or in combination with each other and, in particular, can be incorporated into the compositions by impregnation.

When processing the exhaust gases of the system described above by known methods installed in the exhaust of motor vehicles.

Further, the present invention is illustrated in the examples.

Example 1

This example relates to the preparation of the first method according to the invention, a composition based on zirconium oxide dispersed on a carrier of alumina, when the respective mass fractions of oxides, equal to 30% and 70%.

Previously conducted preparation of colloidal solution of ZrO₂. To this concentrated solution of ZrO(NO₃)₂diluted permuteran water to obtain 600 ml of a solution of ZrO(NO₃)₂concentration equal to 80 g/l in terms of ZrO₂pH is equal to 2. Instantly added a 28% solution of NH₃so of course the pH reached 10, and observed the formation of sludge. The precipitate was filtered, then washed with 6 l of permuteran water. The filter cake is re-suspended in permuteran water (pH=7,5) and acidified by addition of 68% nitric acid solution so that the suspension concentration was 10 wt.% in terms of ZrO₂. After keeping under stirring for one night got a clear view of the colloidal solution, the particle size of which is measured using quasi-elastic light scattering, was 4 nm.

To 430 g of this colloidal solution under stirring was added aminocaproic acid in order to increase pH and to stabilize it with the value of 4.5 (98% 6-aminocaproic acid obtained from Aldrich), and then with stirring, was added 100 g of the powder of the transition gamma-alumina subjected to calcination at 500°C. and having a specific surface area of 320 m²/g, pore volume of 0.82 cm²/g and a loss on ignition of 5.1%. Thus obtained suspension was maintained for 30 minutes under stirring, and then sprayed at 110°C. (outlet temperature 110°C, inlet temperature 220°C) and flow rate of 1 l/h of the Obtained powder was subjected to calcination in air at 700°C for 4 hours.

Example 2

This example relates to the production on the fifth method according to the invention the composition n the basis of zirconium oxide on a carrier of alumina in the respective mass fractions of oxides, equal to 30% and 70%.

In the reactor while stirring the mixed 44,25 g of powdery aluminum oxide from example 1 with 420 ml of water to which was added 14.5 g of concentrated HNO₃to achieve a pH of 1.5. Then added 89,45 g ZrO(NO₃)₂dissolved in 138,3 ml of water. After this was added 10% NH₄OH to bring the pH to 7.

The system was placed in an autoclave and maintained at 150°C under stirring speed of 300 rpm for 4 hours.

The cooled mixture was separated by filtration, and 3 times washed at room temperature for a volume of water equal to the volume of the original solution. The residue after filtration was then subjected to calcination in air at 700°C for 4 hours.

Example 3

This example relates to the production of compositions based on titanium oxide on a carrier of alumina in the respective mass fractions of oxides, equal to 30% and 70%.

Pre-prepared colloidal solution of TiO₂. 32 g of the solution TiOCl₂(25 wt.% in terms of TiO₂) was cooled to 3-4°C, followed by stirring instantly added to 768 g permuteran water, supported at 3-4°C. after addition was added 1 ml of 20% solution of NH₃that led to the emergence of colloids. The reaction mixture is kept at 3-4°C for 10 min under stirring. The mixture is then washed by dialysis relatively VT is mounted water within 48 hours. The washed and extracted at the end of dialysis colloidal solution was concentrated using a tangential ultrafiltration, which led to the final concentration value of at TiO₂equal to 2.1 wt.%. The size of the aggregates measured by the method of quasielastic light scattering, was 7 nm when the index polydispersity, equal to 0.35.

A mixture containing 70% Al₂O₃and 30% of TiO₂, was obtained by mixing 7 g of alumina powder dispersed in 70 ml of water, to which was added 1 g of HNO₃in order to achieve a pH equal to 2 into the reactor under stirring. Used aluminum oxide represented a transition gamma alumina stabilized with silicon, in weight percentage, equal to 90% alumina and 10% silica and having a specific surface after calcination at 600°C, equal to 278 m²/, Then added 142,9 g 2,1% colloidal solution of TiO₂.

Thus obtained suspension was maintained for 30 minutes under stirring, and then sprayed at 110°C. (outlet temperature 110°C, inlet temperature 220°C) and flow rate of 1 l/h of the Obtained powder was subjected to calcination in air at 700°C for 4 hours.

Example 4

This example relates to the production on the fifth method according to the invention the composition of the oxide ZrTiO₄on the media aluminum oxide comply with the mass fractions of oxides, equal to 30% and 70%.

In the reactor while stirring the mixed 44,25 g of powdery aluminum oxide from example 1 with 500 ml of water to which was added 11.4 g of concentrated HNO₃to reach pH 1. Then added 52 g ZrOCl₂and 28.2 g TiOCl₂dissolved in 203 ml of water. After this was added to 95 g of 10% NH₄OH (with a speed of 10 ml/min) in order to bring the pH to 7.

Then in the same manner as in example 2, was carried out by autoclaving, washing and roasting.

RD-analysis performed on the obtained composition and of the same composition after firing at 900°C for 4 hours and at 1000°C for 4 hours, allowed to establish the existence of a single phase ZrTiO₄.

The following examples are comparative examples in which applied the known impregnation method.

Comparative example 5

This example relates to the preparation of a composition based on zirconium oxide on a carrier of alumina in the respective mass fractions of oxides, equal to 30% and 70%.

A similar composition was obtained by dry impregnation ratio of 36.9 g of alumina of example 1 with an aqueous solution containing 74,54 g ZrO(NO₃)₂.

Then the powder was dried at 110°C for 2 hours in a ventilated drying Cabinet and subjected to calcination in air at 700°C for 4 hours.

Comparative example 6

This example belongs to p. the receiving composition based on titanium oxide on a carrier of alumina in the respective mass fractions of oxides, equal to 30% and 70%.

A similar composition was obtained by dry impregnation 16,39 g of alumina of example 1 17.9 g TiOCl₂dissolved in water.

Then the powder was dried at 110°C for 2 hours in a ventilated drying Cabinet and subjected to calcination in air at 700°C for 4 hours.

Comparative example 7

This example relates to the production of compositions based on titanium oxide and zirconium oxide on a carrier of alumina in the respective mass fractions of oxides, equal to 30% and 70%.

A similar composition was obtained by dry impregnation 16,39 g of alumina of example 1 with an aqueous solution containing KZT 12.39 g ZrOCl₂and 6,72 g TiOCl₂.

Then the powder was dried at 110°C for 2 hours in a ventilated drying Cabinet and subjected to calcination in air at 700°C for 4 hours.

In the following next table summarizes the characteristics of the compositions obtained in the various examples, i.e. their specific surface area by BET and the size of the oxide particles on the media at different temperatures of firing.

Roasting mentioned in the table, held for songs that have already been fired at 700°C.

Preliminarily it should be noted that for the compositions according to the invention from examples 1-4 RD-analysis conducted on the compositions obtained directly after the implementation described in the examples, methods, i.e. after firing at 700°C, did not allow the predelete the size of the oxide particles on the media.

This means that was the limit of detection of way RD, which implies that the particle size is less than about 2 nm.

It is seen that the composition of the invention in General contain oxides on the carrier, the particle size of which is considerably less compared to the oxides in the compositions obtained by the known impregnation method.

In the particular case of example 4, the oxide on the carrier after firing at 900°C and 1000°C is present in the form of pure phase ZrTiO₄whereas in comparative example 7 this oxide is present in the form of a mixture of phases ZrO₂, TiO₂and ZrTiO₄. The particle sizes shown in the table for example 7, correspond to the size of the particles ZrTiO₄. Particles ZrO₂and TiO₂have a large size, having approximately the same order as for the other comparative examples.

The accompanying drawing represents the x-ray diffraction pattern obtained for the products of examples 4 and 7 after firing at 900°C.

1. Catalytic composition comprising at least one oxide on the carrier, selected from among zirconium oxide, oxide Titus is on or mixed oxide of zirconium and titanium, supported on a carrier of alumina or oxyhydroxide aluminum, and having, after calcination at 900°C for 4 h, the particle size of the oxide on the media:
not more than 10 nm, if the oxide on the carrier obtained on the basis of zirconium oxide, or
not more than 15 nm, if the oxide on the carrier based on titanium oxide or a mixed oxide of zirconium and titanium.

2. The composition according to claim 1, characterized in that the carrier based on alumina or oxyhydroxide aluminum, stable and/or doped with at least one stabilizing element selected from among rare earth elements, barium, strontium and silicon.

3. The composition according to claim 1 or 2, characterized in that the oxide content on the media it is not more than 50 wt.%, more preferably from 20 to 30 wt.%.

4. The composition according to claim 1 or 2, characterized in that the oxide on the carrier is an oxide of zirconium and at least one element M selected from among praseodymium, lanthanum, neodymium and yttrium.

5. The composition according to claim 1 or 2, characterized in that after firing at 900°C for 4 h, the particle size of the oxide on the carrier is not more than 9 nm, if the oxide on the carrier is a zirconium oxide, and not more than 10 nm, if the oxide on the carrier is a titanium oxide or a mixed oxide of zirconium and titanium.

6. Catalytic composition containing at least one oxide on the carrier, selected from among zirconium oxide, titanium oxide or a mixed oxide of zirconium and titanium supported on a carrier of alumina or oxyhydroxide aluminum, and having, after calcination for 4 hours at 1000°C, the particle size of the oxide on the media:
not more than 20 nm, preferably not more than 17 nm, if the oxide on the carrier obtained on the basis of zirconium oxide, or
not more than 30 nm, if the oxide on the carrier based on titanium oxide or a mixed oxide of zirconium and titanium.

7. The method of preparation of the catalytic composition according to any one of claims 1 to 6, characterized in that it comprises the following stages:
bringing colloidal dispersions of compounds of zirconium and/or titanium, and may compound of the element M in contact with the connection of aluminum selected from aluminum oxide, hydroxides or oxyhydroxides aluminium;
spray drying of the thus obtained mixture;
firing the dried product obtained in this way.

8. The method of preparation of the catalytic composition according to any one of claims 1 to 6, characterized in that it comprises the following stages:
obtaining a liquid mixture containing a salt of zirconium or titanium, and possibly the element M and the connection of aluminum selected from aluminum oxide, hydroxides or oxyhydroxides aluminium;
heating the thus obtained mixture to a temperature equal to at least 100°C;
from the treatment of the thus obtained precipitate;
firing is referred to sludge.

9. The method of preparation of the catalytic composition according to any one of claim 2 to 6, characterized in that it comprises the following stages:
a₁) obtaining a liquid mixture containing a colloidal dispersion of oxide on the media and, perhaps, the oxide of the element M, the connection of aluminum selected from aluminum oxide, hydroxides or oxyhydroxides aluminum, and connect the stabilizing element;
b₁) bringing the above-mentioned mixture in contact with the ground with obtaining a suspension containing the precipitate;
in₁) drying the suspension thus obtained;
g₁) firing thus obtained dried product.

10. The method according to claim 9, characterized in that before step₁the suspension obtained at the end of stage b₁subjected to aging.

11. The method of preparation of the catalytic composition according to any one of claim 2 to 6, characterized in that it includes the following stages:
and₂) obtaining a liquid mixture containing a colloidal dispersion of oxide on the media and, perhaps, the oxide of the element M and the connection of aluminum, selected from among aluminum oxide, hydroxides or oxyhydroxides aluminium;
b₂) bringing the above-mentioned mixture in contact with the ground with obtaining a suspension containing the precipitate;
in₂) adding to the suspension obtained in this way, the connection stable welding temperature, the ith element;
g₂) drying of the suspension obtained in the previous step;
d₂) firing thus obtained dried product.

12. The method according to claim 11, characterized in that before step₂the suspension obtained at the end of stage b₂expose aging.

13. The method of preparation of the catalytic composition according to any one of claims 1 to 6, characterized in that it includes the following stages:
obtaining a liquid mixture containing compound of aluminum, selected from among aluminum oxide, hydroxides or oxyhydroxides aluminum, and at least one salt of zirconium or titanium, and may element M;
bringing the mixture into contact with a base to obtain a precipitate;
removing the precipitate obtained in this way;
firing above the sediment.

14. The method according to item 13, wherein the precipitate obtained after adding the substrate, is subjected to aging.

15. The catalytic system, characterized in that it contains a composition according to any one of claims 1 to 6.