DE102013014241A1 - Process for the preparation of a catalyst, catalyst and process for the oxidative dehydrogenation of hydrocarbons - Google Patents

Abstract

The invention relates to a process for producing a catalyst, wherein a catalyst is provided in the form of a metal oxide catalyst comprising at least one element selected from Mo, Te, Nb, V, Cr, Dy, Ga, Sb, Ni, Co, Pt and Ce having. According to the invention it is provided that the catalyst K is subjected to a post-treatment to increase the proportion of the M1 phase, wherein the catalyst K is brought into contact with water vapor at a pressure below 100 bar to produce a post-treated catalyst K 'and / or in contact with oxygen is brought. The invention further relates to a catalyst K 'produced by the process and to a process for the oxidative dehydrogenation with a catalyst K' according to the invention.

Description

The invention relates to a process for the preparation of a catalyst according to claim 1, to a catalyst prepared thereby according to claim 11 and to a process for oxidative deheating according to claim 12.

In such a process for producing a catalyst to be used particularly in an oxidative dehydrogenation, there is provided a catalyst in the form of a metal oxide catalyst comprising at least one of Mo, Te, Nb, V, Cr, Dy, Ga, Sb , Ni, Co, Pt and Ce.

Such metal oxide catalysts and in particular metal oxide catalysts of the general composition MovTeNbO _x are known from the prior art and are also used for oxidative processes. To describe z. B. K. Amakawa et al. in ACS Catalysis, 2013, 3, 1103-1113 the selective oxidation of propane and benzyl alcohol. Products are acrylic acid or benzaldehyde. In this case, the M1 phase of the catalyst is attributed a crucial role for the catalytic effect. The M1 phase is a bronze-like crystalline structure consisting of a network of octahedrally located molybdenum and vanadium centers linked by common oxygen atoms in the corner positions. These units form a structure of repeating layers with five-, six- and seven-membered channels perpendicular to the layers. Niobium is located within the five-membered channels, while tellurium partially occupies the channels formed by six and seven octahedrons, respectively. A detailed description of the crystalline structure can be found DeSanto, P., Jr., et al., Structural aspects of the M1 and M2 phases in MoVNbTeO propane ammoxidation catalysts. Journal of Crystallography, 2004. 219 (3): p. 152-165 ,

Furthermore, in the prior art, the oxidative dehydrogenation (also referred to as ODH) of ethane and propane to the corresponding olefins in F. Cavani et al., Catalysis Today 2007, 127, 113-131 described in detail. Here, among other things, the coking problem and the resulting rapid deactivation of the catalyst used as a technological challenge pointed out. In P. Botella, E. Garcia-Gonzalez, A. Dejoz, JM Lopez-Nieto, MI Vazquez, J. Gonzalez-Calbet, "Selective Oxidative Dehydrogenation of Ethanes on MoVTeNbO Mixed Metal Oxide Catalysts", Journal of Catalysis 225 (2004), 428-438 and F. Ivars, P. Botella, A. Dejoz, JM Lopez-Nieto, P. Concepcion, MI Vazquez, "Selective Oxidation of Short-Chain Alkanes over Hydrothermally Prepared MoVTenBo Cataylsts", Topics in Catalysis 38 (2006), 59-67 are described by the authors known MoVTeNbO _x catalysts. Furthermore, detailed descriptions can be found in Catalysis Today 2004, 91-92, 241-245 and in Catalysis Today 2010, 157, 291-296 , Here, investigations on ODH with MoVTeNbOx catalysts with yields of up to 75% are explicitly described. Here, too, the presence of an M1 phase is regarded as a decisive criterion. Furthermore, there is a current overview in C. Gärtner, AC van Veen, JA Lercher, ChemCatChem 2013, 5, doi: 10.1002 / cctc.201200966 , Here, the current state of the art to various catalyst systems is described, in particular vanadium oxide, molybdenum Mischmetalloxid-, Ni, Co, rare earth, supported alkali metal or chloride-based systems.

Furthermore, there is a detailed explanation of the importance of the M1 phase for the propane oxidation to propylene in R. Schlögl, Topics Catalysis 2011, 54, 627-638 , It also emphasizes the importance of VxOy species.

Finally, will also be in EM Thorsteinson, TP Wilson, FG Young, PH Kasai (Journal of Catalysis 52 (1977), 116-132) "The Oxidative Dehydrogenation of Ethane over Catalysts Containing Mixed Oxides of Molybdenum and Vanadium" treated the ODH of ethane over mixed oxide catalysts with Mo and V.

In an oxidative process such as ODH, oxygen (eg in the form of air) is used. Therefore, it may come to the outlet of the reactor device to a residual content of O ₂ . This means a challenge in the subsequent decomposition part, where it can lead to accumulations and formation of ignitable mixtures.

Previously known catalysts can not usually be operated in the range of low oxygen residual concentrations. In general, when the material is heated under reducing conditions, a partial self-reduction is observed here so that part of the metal is no longer present as an oxide, which impairs the stability of the crystal structure, which can lead to collapse of this structure. According to the prior art, on the one hand, therefore, this can be achieved only by appropriate dilution or by the involvement of an additional apparatus for oxygen removal downstream of the reactor device, such. In US20100256432 described, be accomplished.

Furthermore, the concerns US2005085678 as well as the WO2010096909 a catalyst for the ODH. The US2001025129 describes a NiO catalyst for the ODH. The US4899003 describes a method for the ODH with a multi-stage reactor. Furthermore, from the US4739124 Such a method with at least two beds known.

The WO2005060442A2 relates to the production of olefins by ODH with an additional CO feed. The WO2010115108A1 relates to a process for ethylene production by means of ODH and the WO2010115099A1 relates to a process for the treatment of a catalyst for the production of olefins from a hydrocarbon.

Furthermore, the describes DE 11 2009 000 404 T5 a "pTT treatment" to increase the proportion of the M1 phase in which a MoVTeNbOx catalyst is treated with steam. Without exception, very high pressures of at least 10 MPa and temperatures greater than 400 ° C are required.

On this basis, it is an object of the present invention to provide an improved process for the preparation of a catalyst or a catalyst and a process for the oxidative dehydrogenation with such a catalyst.

This object is achieved by a method having the features of claim 1.

Advantageous embodiments are specified in the associated subclaims.

According to claim 1, it is provided that the catalyst is subjected to an after-treatment to increase the proportion of the M1 phase (in the present case, the M1 or M 2 content is always stated below as weight percent, whereby this M1 content or M2 content relates in each case to the entire catalyst material in crystalline and amorphous form), wherein the catalyst is brought to form an aftertreated catalyst with water vapor at a pressure below 100 bar, preferably below 80 bar, preferably below 50 bar in contact and / or with Oxygen is brought into contact.

By the aftertreatment of the catalyst according to the invention, an optimization of the catalyst for oxidative reactions, in particular for the oxidative dehydrogenation of alkanes, can be achieved. In particular, this is done by the above-mentioned exposure to steam (also referred to as steaming) and / or the above exposure to oxygen. It has been shown that this surprisingly increases the proportion of the effective M1 phase in particular comparatively low pressures and thus the catalyst can be made more robust and stable. This concerns z. As the operation at low oxygen concentrations. At the same time, the proportion of unselective by-products (CO and CO ₂ ), which contribute significantly to the release of heat, minimized, so that there are corresponding advantages for a technical process using the aftertreated catalyst.

The contacting of the catalyst in the aftertreatment with water vapor and / or oxygen is preferably carried out by the catalyst is subjected to a stream comprising water vapor and / or oxygen. This can be carried out in particular in a reactor device in which the aftertreated catalyst is subsequently used for an ODH (see below).

According to a preferred embodiment it is provided that the catalyst in the after-treatment at a temperature of at least 200 ° C, preferably at a temperature of at least 350 ° C, preferably at a temperature of at least 350 ° C, preferably at a temperature in the range of 200 ° C to 650 °, preferably at a temperature in the range of 300 ° C to 650 ° C, preferably at a temperature in the range of 350 ° C to 600 ° C, preferably at a temperature in the range of 350 ° C to 550 ° C. , preferably at a temperature in the range of 350 ° C to 400 ° C, or preferably at a temperature in the range of 400 ° C to 500 ° C, is brought into contact with the water vapor.

Furthermore, it is provided according to a preferred embodiment of the invention that the catalyst in the after-treatment at a temperature of at least 200 ° C, preferably at a temperature of at least 350 ° C, preferably at a temperature of at least 400 ° C, preferably at a temperature in the range of 200 ° C to 650 ° C, preferably at a temperature in the range of 300 ° C to 650 ° C, preferably at a temperature in the range of 350 ° C to 600 ° C, preferably at a temperature in the range of 350 ° C to 550 ° C, preferably at a temperature in the range of 350 ° C to 400 ° C, or preferably at a temperature in the range of 400 ° C to 500 ° C, is brought into contact with the oxygen.

Furthermore, it is provided according to a preferred embodiment that the catalyst in the aftertreatment with the steam at a pressure in the range of 0.5 bar to 100 bar, preferably 0.5 bar to 90 bar, preferably 0.5 bar to 80 bar, preferably 0.5 bar to 70 bar, preferably 0.5 bar to 60 bar, preferably 0.5 bar to 50 bar, preferably 0.5 bar to 40 bar, preferably 0.5 bar to 30 bar, preferably 0.5 bar to 20 bar, preferably 0.5 bar to 10 bar, preferably 0.5 bar to 5 bar, preferably 0.5 bar to 4 bar, preferably 0.5 bar to 3 bar, preferably 0.5 bar to 2 bar, preferably 0 , 5 bar to 1.5 bar, preferably 0.8 bar to 1.2 bar, preferably 0.9 bar to 1.1 bar, preferably at 1 bar, is brought into contact.

Furthermore, it is provided according to a preferred embodiment of the invention that the catalyst in the aftertreatment with the oxygen at a pressure in the range of 0.5 bar to 100 bar, preferably 0.5 bar to 90 bar, preferably 0.5 bar to 80 bar , preferably 0.5 bar to 70 bar, preferably 0.5 bar to 60 bar, preferably 0.5 bar to 50 bar, preferably 0.5 bar to 40 bar, preferably 0.5 bar to 30 bar, preferably 0.5 bar up to 20 bar, preferably 0.5 bar to 10 bar, preferably 0.5 bar to 5 bar, preferably 0.5 bar to 4 bar, preferably 0.5 bar to 3 bar, preferably 0.5 bar to 2 bar, preferably 0.5 bar to 1.5 bar, preferably 0.8 bar to 1.2 bar, preferably 0.9 bar to 1.1 bar, preferably at 1 bar, is brought into contact.

Preferably, the catalyst provided is obtained before the post-treatment by calcining a catalyst-precursor mixture. For this purpose, the catalyst precursor mixture, which is preferably obtained by means of a hydrothermal synthesis, z. B. in an oxygen-containing atmosphere for a predefinable period of time, in particular in the range of 2 h to 4 h, a predefinable temperature, in particular in the range of 175 ° C to 250 ° C, exposed and then preferred in a stream of an inert gas for a pre-definable Period of time, in particular in the range of 2 hours to 6 hours, exposed to a predefinable temperature, in particular in the range of 600 ° C to 650 ° C. The respective temperature is preferably set at a heating rate in the range of 5 ° C / min to 15 ° C / min. The flow of the inert gas is preferably in the range from 50 ml / min to 150 ml / min, preferably 100 ml / min. The calcination can take place at atmospheric pressure.

In the said hydrothermal synthesis, an aqueous solution of ammonium heptamolybdate tetrahydrate, telluric acid, vanadyl sulfate and niobium (V) ammonium oxalate hydrate is preferably mixed with stirring at 80 ° C., the resulting suspension being stirred at elevated temperature, preferably at temperatures within the range from 175 ° C to 185 ° C, and a synthesis time in the range of preferably 24 hours to 120 hours is stirred.

In particular, the calcination removes the volatile constituents of the precursor mixture and in particular converts the metal elements of the catalyst into their respective oxides.

According to a preferred embodiment, the catalyst to be subjected to the post-treatment is a metal oxide catalyst comprising the elements Mo, V, Te, Nb.

Preferably it is in the ready joined, the post-treatment to be subjected to catalyst is a catalyst of the class MoV _a Te _b Nb _c O _x, where a is preferably in the range of 0.05 to 0.4, and wherein b is preferably in the range of 0 , 02 to 0.2, and wherein c is preferably in the range of 0.05 to 0.3.

In a further embodiment, a is preferably in the range of 0.12 to 0.25, wherein b is preferably in the range of 0.04 to 0.1, and wherein c is preferably in the range of 0.1 to 0.18.

In the above formula MoV _a Te _b Nb _c O _x , x is the molar number of oxygen that binds to the metal atoms of the catalyst, which follows from the relative amount and valency of the metal elements. This can also be expressed by the formula Mo ^s V _a ^p Te _b ^q Nb _c ^r O _x , where s, p, q, r are the oxidation states of Mo, V, Te and Mb, respectively, and 2 x = x s + p · a + b · q + c · r. Mo can be present in the oxidation state +5 as well as in the oxidation state +6. V can be present in the oxidation state +4 and +5, depending on the position in the crystal. Niobium is present in the +5 oxidation state. Tellurium is present in the oxidation state +4.

According to a preferred embodiment, it is further provided that the catalyst in the after-treatment for a period of at least one hour, in particular for a period of time in the range of one hour to one week, in particular for a period in the range of one hour to 24 hours, especially for a Time range in the range of one hour to 12 hours, in particular for a period in the range of one hour to 11 hours, in particular for a period in the range of one hour to 10 hours, in particular for a period in the range of one hour to 9 hours, in particular for a period in the range of one hour to 8 hours, in particular for a period in the range of one hour to 7 hours, in particular for a period of time Range of one hour to 6 hours, in particular for a period in the range of one hour to 5 hours, in particular for a period in the range of one hour to 4 hours, in particular for a period in the range of one hour to 3 hours, in particular for a Time span in the range of one hour to two hours, is brought into contact with water vapor.

According to a preferred embodiment it is provided that the catalyst in the after-treatment for a period of at least one hour, in particular for a period in the range of one to five hours, in particular for a period of time of one to 4 hours, in particular for a period of time Range of one to three hours, especially for a period of time of one to three hours, especially for a period of time in the range of one to two hours is brought into contact with oxygen.

According to a preferred embodiment, it is further provided that the catalyst is brought into contact during the aftertreatment with a mixture comprising water vapor and oxygen, wherein in this case preferably the temperature of water vapor and oxygen, the period of contact with the mixture and the prevailing pressure in the respective Intersection of the areas for water vapor and oxygen with separate contacting are.

Alternatively, the catalyst is preferably brought into contact with the after-treatment in any sequence, in particular alternately, either with water vapor or with oxygen, in particular in the above-mentioned conditions in terms of temperature, pressure and time span, where also sequences can be present in which Catalyst with the above mixture of water vapor and oxygen is applied.

According to a preferred embodiment, the catalyst is brought into contact with the oxygen in the after-treatment, by oxygen in the form of pure oxygen (the concentration of oxygen preferably at least 90 vol .-%, at least 95 vol .-%, at least 98 vol % or at least 99% by volume), in the form of air, in particular oxygen-enriched or depleted air, or in the form of a mixture comprising oxygen and at least one further gas, in particular from the group steam, He, Ar and N ₂ , wherein oxygen in the mixture preferably with a concentration greater than or equal to 10 vol .-%, in particular greater than or equal to 20 vol .-%, in particular greater than or equal to 30 vol .-%, in particular greater than or equal to 30 vol. %, in particular greater than or equal to 40% by volume, in particular greater than or equal to 50% by volume, in particular greater than or equal to 60% by volume, in particular greater than or equal to 70% by volume, in particular Other greater than or equal to 80 vol .-%, in particular greater than or equal to 90 vol .-%, in particular greater than or equal to 95 vol .-%, in particular greater than or equal to 98 vol .-%, in particular greater than or equal to 99 vol .-% is present ,

According to a further preferred embodiment, the oxygen required for the aftertreatment of the catalyst is provided by means of a known pressure swing adsorption.

Furthermore, the problem according to the invention is solved by a catalyst having the features of claim 11, which was produced by the production or after-treatment process according to the invention.

Furthermore, the problem of the invention by a method for oxidative dehydrogenation with the features of claim 12 is achieved.

Thereafter, it is envisaged that the ODH process comprises the process steps of the production process according to the invention, wherein a feed stream containing an alkane (preferably having two to four carbon atoms), in particular ethane, is fed in a reactor means the aftertreated catalyst, wherein by oxidative dehydrogenation of the alkane with Oxygen in the presence of the aftertreated catalyst an alkene-containing product stream is generated.

According to a preferred embodiment it is provided that the catalyst outside the reactor device is subjected to the aftertreatment, z. Example, at a location remote from the reactor device location, and then transported in after-treated form, ie, after the aftertreatment, to Reaktoreinrichung is and is arranged as intended in the reactor device. After this, the aftertreated catalyst can be used in the reactor equipment for the ODH.

According to a preferred alternative embodiment, it is provided that the (possibly calcined) catalyst is disposed in the reactor device according to the intended purpose before the aftertreatment, and then subjected to aftertreatment in the reactor device and used after the aftertreatment in the same reactor device for the ODH. This has the particular advantage that any existing technical facilities, such. B. a steam or oxygen feed into the reactor device are already present and can therefore be used for the aftertreatment.

In principle, there is the possibility that several, z. B. parallel connected, reactor devices can be used. So z. B. in a reactor device an ODH be performed while in another reactor means the catalyst is being replaced or a catalyst is post-treated according to the invention or a catalyst is regenerated with a suitable procedure. As a result, z. B. be ensured that an ODH can be carried out continuously. So z. B. be switched from a reactor device with catalyst in need of replacement to a reactor device with fresh, post-treated catalyst. In the taken out of the process catalyst device then a new catalyst can be filled and there optionally aftertreated while the ODH continues in the other reactor device.

According to a further preferred embodiment it is provided that a diluent is introduced into the reactor device which is inert or has at least one inert component, in particular to control the heat of reaction in the oxidative dehydrogenation of the alkane, in particular an explosion in the oxidative dehydrogenation of the alkane to prevent.

The diluent used is preferably one of the following substances or a combination of several of the following: water vapor, nitrogen and / or air.

Furthermore, to control the heat of reaction in the ODH, the catalyst itself may be diluted with an inert material. In this case, the catalyst can be diluted before the aftertreatment according to the invention with the inert material or after the aftertreatment according to the invention. The inert material may preferably be one of the following or any combination of the following: alumina, silica, silicon carbide, quartz or ceramics.

The (in particular post-treated) catalyst may, for. B. in the reactor device in the form of at least one fixed bed, which is formed from at least a plurality of those catalyst having first particles, in particular those first particles also have the inert material and / or wherein the fixed bed for diluting the catalyst with a plurality of the first particles mixed second particles, which are formed from the inert material.

Furthermore, oxygen or air is preferably introduced into the reactor device to provide oxygen as the oxidant. In this case, nitrogen can be enriched or discharged in the air, furthermore, oxygen can be enriched or depleted in the air.

Further details and advantages of the invention will be explained by the following description of exemplary embodiments with reference to the figures.

Show it:

1 a diagram in which on the abscissa A the velocity constant k ₁ (μmolg ^-1 s ^-1 bar ^-1 ) for the ODH C ₂ H ₆ -> C ₂ H ₄ at 370 ° C is given and on the ordinate B the M1 Concentration of each MoVTeNbO _x catalyst used;

2 a diagram in which on the abscissa A ', the concentration of V (V / (Mo + V + Te + Nb)) is indicated on the surface of the MoVT _e N _b O _x catalyst and on the ordinate B, the M1 concentration the catalyst;

3 a block diagram of an apparatus for carrying out the process according to the invention for the oxidative dehydrogenation of alkanes;

4 a diagram in which on the lower abscissa D is the time in hours and on the upper abscissa G, the O ₂ concentration at the inlet of the reactor device (mol%) is plotted on the ordinate, the conversion of O ₂ and C ₂ H _{6 is} plotted in%;

5 a diagram in which on the lower abscissa the D is the time in hours and on the upper abscissa G 'the O ₂ concentration at the inlet of the reactor device (mol%) is plotted on the ordinate the yield of CO, CO ₂ and C ₂ H _{4 is} plotted in%;

6 a diagram in which on the abscissa the sample number of 12 different catalyst patterns K 'and plotted on the ordinate of the respective proportion of M1, M2 and amorphous phase; and

7 two diagrams in which the abscissa shows the temperature in ° C during the passage of a temperature profile and the ordinate represents the respective proportion of M1 and M2 phase (in this section, the% data refers only to the ratio) M1 to M2 phase, the amorphous portion is not taken into account here). In the upper diagram, the catalyst was aftertreated only under helium atmosphere, while it was treated in the lower diagram under synthetic air (each at a pressure of 1 bar).

• – MoV_0,08-0,4Te_0,02-0,2Nb_0,08-0,30O_x,
• – insbesondere MoV_0,12-0,25Te_0,0a-0,10Nb_0,10-0,18O_x,

in Betracht (auch Varianten mit zusätzlichen Dotierungen mit weiteren Metallen, z. B. Sb sind möglich). Prinzipiell ist aber auch die Verwendung anderer geeigneter Katalysatoren, z. B. basierend auf den Metallen V, Cr, Dy, Ga, Sb, Mo, Ni, Nb, Co, Pt, oder Ce bzw. deren Oxiden oder auch Mischungen, insbesondere Vanadiumoxide, NiNbOx, denkbar. Der Katalysator kann auch durch ein geeignetes Inertmaterial verdünnt bzw. im Katalysatorkörper verdünnt sein.For the aftertreatment according to the invention, according to one embodiment of the invention, preference is given to using a catalyst K of the composition

• MoV _0.08-0.4 Te _0.02-0.2 Nb _0.08-0.30 O _x ,
• In particular MoV _0.12-0.25 Te _0.0a-0.10 Nb _0.10-0.18 O _x ,

into consideration (variants with additional doping with other metals, eg Sb are possible). In principle, however, the use of other suitable catalysts, for. B. based on the metals V, Cr, Dy, Ga, Sb, Mo, Ni, Nb, Co, Pt, or Ce or their oxides or mixtures, in particular vanadium oxides, NiNbOx, conceivable. The catalyst may also be diluted by a suitable inert material or diluted in the catalyst body.

For practical implementation, it then depends on maximizing activity and selectivity.

In the case of the preferred catalyst K mentioned above, this maximization is promoted inter alia by the proportion of the M1 phase. The proportion of this M1 phase is crucial for the selective oxidation of hydrocarbons and the highest possible ratio M1: M2 is to be strived for.

6 shows the distribution between M1, M2 and amorphous phase for various inventively post-treated catalyst pattern K '. The proportion of M1 phase varies between 20% by weight and 90% by weight, while the proportion of M2 phase is below 10% by weight. The remainder is present as an amorphous phase. By post-treatment, M1 contents of between 20% by weight and at least 90% by weight, preferably more than 70% by weight, can be achieved. Preferably, M2-phase fractions of less than 5% by weight and not more than 30% by weight of amorphous phase are achieved here.

For this purpose, the catalyst K can first be prepared by a suitable synthesis. In the case of the present invention, for. B. the hydrothermal synthesis can be used (see Example 1).

Surprisingly, it was found that the proportion of the M1 phase could be further increased by the treatment steps according to the invention, whereby M1 contents of more than 90% by weight were achieved.

As in 1 experiments have shown that the M1 phase is the only active phase in the ODH. Although the M2 phase can further oxidize the alkene, it does not activate the underlying alkane. This can easily be seen from 1 which shows the rate constant k ₁ (in units of μmolg ^-1 s ^-1 bar ^-1 ) for the ODH C ₂ H ₆ -> C ₂ H ₄ at 370 ° C on the abscissa A and the M1 concentration (in % By weight) of the particular MoVTeNbO _x catalyst used on the ordinate B. Thereafter, the rate constant increases in proportion to the concentration of the M1 phase.

It has been found that for the above catalysts, the M1 concentration can be increased when the catalyst z. B. according to Examples 2 and 3 with steam (so-called "steaming") as well as with oxygen or air according to Examples 4 and 5 is treated.

The air used here may also be synthetically produced or be enriched in oxygen or nitrogen. In particular, the use of pressure swing adsorption process or the recourse to an existing air separation plant, if appropriate infrastructure is available, comes into consideration. Furthermore, such a treatment step can also take place by feeding in a further inert or dilution medium or a mixture can also be used (for example a mixture of steam and (for example synthetic) air or oxygen).

Furthermore, it has been shown that the V content represents a relevant size on the surface of the catalyst. In this regard, it was found that, apart from the proportion of the crystalline M1 phase, the amount of vanadium at the surface, which by means of LEIS spectroscopy (this is the so-called low-energy ion scattering, a spectroscopic method that the chemical The composition of the outermost layer of a solid can be measured), both with the ethene yield and with the M1 proportion correlated, as in 2 is plotted on the abscissa A ', the concentration of vanadium (V / (Mo + V + Te + Nb)) on the surface of the MoVTeNbO _x catalyst and on the ordinate B, the M1 concentration of the catalyst.

example 1

To carry out the aftertreatment according to the invention, several MoV _y Te _0.1 Nb _0.1 O _x catalysts with y from the range 0.25 to 0.45 were prepared by a hydrothermal synthesis. For the preparation of 10 g of MoV _y Te _0.1 Nb _0.1 O _x catalyst, an appropriate amount of ammonium heptamolybdate (NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O was dissolved in 40 mL double-distilled water and heated to 80 ° C , Te, V and Nb precursors - telluric acid Te (OH) ₆ , vanadyl sulfate VOSO ₄ and ammonium niobium oxalate C ₄ H ₄ NNbO ₉ · xH ₂ O - were each dissolved in 10 mL of double distilled H ₂ O. First, the Te solution was added to the Mo at 80 ° C. After stirring for 20 minutes, the V solution was added dropwise over 20 minutes. After stirring the Mo-V-Te solution for 15 minutes, the Nb solution was added and the four-element mixture was stirred for an additional 10 minutes. The synthesis temperature was maintained above 80 ° C throughout the mixing procedure of the reactants. The solution was then placed in an autoclave and made up to a volume of 280 mL with double distilled water.

The remaining volume of gas was purged with N ₂ prior to synthesis. The hydrothermal treatment was carried out at temperatures in the range of 175 ° C to 185 ° C and the synthesis time was 24 to 120 hours. Thereafter, the catalyst was filtered, washed with double-distilled water and dried at 80 ° C overnight. The calcination was carried out in two steps: 2 hours at 250 ° C in synthetic air followed by a thermal treatment at 600 ° C (heating rate 10 ° C / min) for a further 2 hours with an inert gas stream (e.g., N ₂ , Ar or He) of 100 ml / min.

Example 2

It was found that the application of the catalysts K with steam at temperatures between 400 ° C and 500 ° C and a pressure of 1 bar for a period of 1 hour to 24 hours (1 week at 400 ° C gave similar results) the catalytic Performance in terms of activity increased. Analysis of the catalysts by XRD before and after the steam treatment has shown that this increase is due to an increased proportion of the M1 phase (XRD stands for X-ray diffraction, the diffraction patterns obtained by this technique being a Rietveld lattice refinement The amorphous contribution was also quantified by calibration using an amorphous and a highly crystalline standard).

So z. Example, a sample with nominal formula MoV _0.25 Te _0.1 Nb _0.1 O _x (chemical composition determined by ICP-OES: MoV _0.13 Te _0.06 Nb _0.1 0O _x , where ICP-OES to the so-called Inductive Coupled Plasma Optical Emission Spectrometry is) contacted with steam at 500 ° C at 1 bar for 2 hours. In this case, an increase in the M1 content by about 5 wt .-% (from 45 wt .-% to 51 wt .-%) was observed. Consistent with this increase in the active M1 phase, an increase in ethene yield was observed in the activity test (temperature in the range of 370 ° C to 430 ° C, 300 mg catalyst, total flow in the range of 33 to 74 mL / min, Table 1) , Gas composition: molar ratio of C ₂ H ₆ : O ₂ : He = 1: 1: 9): Table 1 M1 (wt%) Ethene yield (400 ° C 66 mL / min) (%) Ethene yield (400 ° C 74 mL / min) (%) Ethene yield (430 ° C 74 mL / min) (%) Before the aftertreatment 45 2.25 1.87 3.80 After the aftertreatment 51 2.59 2.25 4.45

Example 3

Was continued. a sample with nominal formula MoV _0.40 Te _0.10 Nb _0.10 O _x (chemical composition determined by ICP-OES: MoV _0.20 Te _0.05 Nb _0.10 O _x ) contacted with steam at 400 ° C and 1 bar for 2 hours. In this case, an increase in the M1 content according to Table 2 was observed by about 5% by weight (from 84% by weight to 89% by weight) M1 (wt%) Ethene yield (370 ° C 68 mL / min) (%) Ethene yield (400 ° C 68 mL / min) (%) Before the aftertreatment 84 12.2 23.3 After the aftertreatment 89 16.9 27.9

Example 4

The post-treatment of the MoVTeNbOx catalysts for 1 to 2 hours at 400 ° C and a pressure of 1 bar under a flow of 10 vol .-% 02 and 90 vol .-% He or a synthetic air flow also increased the ethane reaction. This increase could again be attributed to an increase in the M1 concentration, as before by further crystallization of the amorphous component and by conversion of the M2 phase into the M1 phase.

So z. B. a sample with nominal formula MoV _0.45 Te _0.1 Nb _0.1 O _x (chemical composition determined by ICP-OES: MoV _0.25 Te _0.07 Nb _0.10 O _x ) 2 hours at 400 ° C and a pressure of 1 bar with O ₂ contacted ( synthetic air with 21 vol.% O ₂ ). It was observed that the M1 content increased by 5% by weight through the post-treatment (from 20% by weight to 25% by weight).

The fresh catalyst K contained about 3.5 wt .-% M2 phase, but only 0.05 wt .-% M2 phase after the post-treatment with O ₂ . By in-situ XRD, it was observed that the post-treatment with O ₂ recrystallizes the inactive M2 phase into the active M1 phase (cf. 7 ). This phenomenon is not observed when the same thermal treatment is carried out under inert gas (cf. 7 ).

As a result of the higher M1 concentration of the post-treated catalyst K ', an increase in the ethene yield in the activity tests (temperature 370 ° C to 430 ° C, 300 mg to 315 mg catalyst, flow 33 mL / min to 74 mL / min) be determined. These results are in the Table 3 summarized: Table 3 M1 (wt%) Ethene yield (370 ° C 33 mL / min) (%) Ethene yield (370 ° C 74 mL / min) (%) Ethene yield (400 ° C 74 mL / min) (%) Before the aftertreatment 20 5.27 2.84 6.07 After the aftertreatment 25 6.44 3.31 6.56

Example 5

Furthermore, a sample with nominal formula MoV _0.40 Te _0.1 Nb _0.1 O _x (chemical composition determined by ICP-OES: MoV _0.27 Te _0.09 Nb _0.10 O _x ) 2 hours at 400 ° C and a pressure of 1 bar contacted with O ₂ . Here, according to Table 4, it was observed that the M1 content increased by 1 wt% by the post-treatment (from 49 wt% to 50 wt%). Table 4 M1 (wt%) Ethene yield (370 ° C, 33 mLmin) (%) Ethene yield (400 ° C, 33 mL / min) (%) Ethene yield (400 ° C, 60 mL / min) (%) Before the aftertreatment 49 22.0 39.2 27.1 After the aftertreatment 50 22.7 40.0 30.2

3 shows an embodiment of the invention for the oxidative dehydrogenation of an alkane to the corresponding alkene, z. Ethane to ethene, using a catalyst K 'of the invention.

Thereafter, as feed gases (feed stream E) an alkane, in this case ethane, and oxygen and / or air as the oxidant 10 in a reactor device 1 fed to a catalyst K, which is a MoVTeNbO _x catalyst after-treated according to the invention.

Here, the catalyst K 'in already post-treated form in the reactor device 1 be introduced or only there by application of steam and / or oxygen to be subjected to a post-treatment (K -> K ') with the M1 content is increased.

In the presence of the catalyst K ', the ethane is oxidatively oxidized to give an ethylene-containing product stream P (in place of ethane, propane and / or butane are also suitable as the insert). This is a highly exothermic process. In particular, in the formation of by-products by over-oxidation to CO and CO ₂ disproportionately much heat is released. For controlled reaction outside explosion areas, therefore, an inert diluent V is added to the reactor equipment 1 initiated, the z. As water vapor 11 can have.

The ethylene-containing stream P is from the reactor device 1 withdrawn and cooled against the insert E. 12 , then cooled further 9 . 8th and in a separator 2 separated into a liquid phase and a gaseous phase. The liquid phase consists essentially of water and is discarded 7 or, if necessary, against the product stream P for generating the water vapor 11 evaporated 9 ,

In a CO ₂ removal unit 3 is removed in the product stream P CO ₂ contained 5 ,

After the CO2 removal unit 3 the product stream P passes through a decomposition part 3 ' in which Inert 4 (For example, N2, Ar, He) and unreacted ethane E 'are removed from the product stream P and into the reactor device 1 or the insert E are returned, with inert 4 as diluent V in the reactor device 1 can be returned or if necessary be led out of the process 6 ,

The reactor device 1 can be both isothermal and adiabatic.

• – Druck in der Reaktoreinrichtung 1 von 0,5 bar bis 35 bar, bevorzugt 1 bar bis 15 bar, besonders bevorzugt 2 bar bis 10 bar.
• – Temperatur in der Reaktoreinrichtung 1 zwischen 250°C bis 650°C, bevorzugt 280°C bis 550°C, besonders bevorzugt 350°C bis 480°C.
• – Feedzusammensetzungen (Einsatzstrom E): bevorzugt 5 Vol.-% bis 60 Vol.-% Ethan, 1 Vol.-% bis 40 Vol.-% O₂, 0 Vol.-% bis 70 Vol.-% H₂O, Rest N₂, bevorzugt 10 Vol.-% bis 55 Vol.-% Ethan, 5 Vol.-% bis 35 Vol.-% O2, 0 Vol.-% bis 60 Vol.-% H₂O, Rest N₂, besonders bevorzugt 30 Vol.-% bis 50 Vol.-% Ethan, 10 Vol.-% bis 30 Vol.-% O₂, 0 Vol.-% bis 50 Vol.-% H₂O, Rest N₂.
• – Die WHSV (weight hourly space velocity) liegt vorzugsweise im Bereich von 1.0 kg bis 40 kg C₂H₆/h/kgKat, bevorzugt im Bereich von 2 kg bis 25 kg C₂H₆/h/kgKat, besonders bevorzugt im Bereich von 5 kg bis 20 kg C₂H₆/h/kgKat.

As process data for the reactor device 1 in the form of an isothermal reactor, e.g. B. carried out as a salt melt reactor, for example, the following parameters can be used:

• - Pressure in the reactor device 1 from 0.5 bar to 35 bar, preferably 1 bar to 15 bar, more preferably 2 bar to 10 bar.
• - Temperature in the reactor device 1 between 250 ° C to 650 ° C, preferably 280 ° C to 550 ° C, more preferably 350 ° C to 480 ° C.
• Feed compositions (feed stream E): preferably 5% by volume to 60% by volume of ethane, 1% by volume to 40% by volume of O ₂ , 0% by volume to 70% by volume of H ₂ O, balance N _2, preferably 10 vol .-% to 55 vol .-% ethane, 5 vol .-% to 35 vol .-% O2, 0 vol .-% to 60 vol .-% H ₂ O, remainder N _2, more preferably 30% by volume to 50% by volume of ethane, 10% by volume to 30% by volume of O ₂ , 0% by volume to 50% by volume of H ₂ O, balance N ₂ .
• The WHSV (weight hourly space velocity) is preferably in the range of 1.0 kg to 40 kg C ₂ H ₆ / h / kg cat, preferably in the range of 2 kg to 25 kg C ₂ H ₆ / h / kg cat, particularly preferably in the range from 5 kg to 20 kg C ₂ H ₆ / h / kg cat.

• – Druck in der Reaktoreinrichtung 1 von 0,5 bar bis 35 bar, bevorzugt 1 bar bis 15 bar, besonders bevorzugt 2 bar 10 bar.
• – Temperatur in der Reaktoreinrichtung 1 zwischen 250°C bis 650°C, bevorzugt 280°C bis 550°C, besonders bevorzugt 350°C bis 480°C.
• – Feedzusammensetzungen (Einsatzstrom E): bevorzugt 1 Vol.-% bis 20 Vol.-% Ethan, 1 Vol.-% bis 15 Vol.-% O₂, 10 Vol.-% bis 95 Vol.-% H₂O, Rest N₂, bevorzugt 1 Vol.-% bis 15 Vol.-% Ethan, 1 Vol.-% bis 10 Vol.-% O₂, 20 Vol.-% bis 90 Vol.-% H₂O, Rest N₂, besonders bevorzugt 2 Vol.-% bis 8 Vol.-% Ethan, 1 Vol.-% bis 5 Vol.-% O₂, 25 Vol.-% bis 80 Vol.-% H₂O, Rest N₂,
• – die WHSV liegt bevorzugt im Bereich von 2.0 kg bis 50 kg C₂H₆/h/kgKat, bevorzugt im Bereich von 5 kg bis 30 kg C₂H₆/h/kgKat, besonders bevorzugt im Bereich von 10 kg bis 25 kg C₂H₆/h/kgKat.
• – Der Anteil des Intermaterials an dem Festbett bzw. Katalysator K, K' beträgt vorzugsweise 30 Vol.-% bis 90 Vol.-%, bevorzugt 50 Vol.-% bis 85 Vol.-%, besonders bevorzugt 60 Vol.-% bis 80 Vol.-%. Ein folgendes optionales zweites oder weiteres Festbett kann ohne Intertmaterial ausgeführt sein.

As process data for the reactor device 1 in the form of an adiabatic reactor z. For example, the following parameters can be used:

• - Pressure in the reactor device 1 from 0.5 bar to 35 bar, preferably 1 bar to 15 bar, more preferably 2 bar 10 bar.
• - Temperature in the reactor device 1 between 250 ° C to 650 ° C, preferably 280 ° C to 550 ° C, more preferably 350 ° C to 480 ° C.
• Feed compositions (feed stream E): preferably 1% by volume to 20% by volume of ethane, 1% by volume to 15% by volume of O ₂ , 10% by volume to 95% by volume of H ₂ O, Residual N ₂ , preferably 1 vol.% To 15 vol.% Ethane, 1 vol.% To 10 vol.% O ₂ , 20 vol.% To 90 vol.% H ₂ O, balance N ₂ , particularly preferably 2% by volume to 8% by volume of ethane, 1% by volume to 5% by volume of O ₂ , 25% by volume to 80% by volume of H ₂ O, balance N ₂ ,
• - The WHSV is preferably in the range of 2.0 kg to 50 kg C ₂ H ₆ / h / kgKat, preferably in the range of 5 kg to 30 kg C ₂ H ₆ / h / kgKat, more preferably in the range of 10 kg to 25 kg C ₂ H ₆ / h / kg cat.
• The proportion of the intermaterial on the fixed bed or catalyst K, K 'is preferably 30% by volume to 90% by volume, preferably 50% by volume to 85% by volume, particularly preferably 60% by volume 80% by volume. A following optional second or further fixed bed can be designed without intert material.

Another aspect is the avoidance of potentially explosive atmospheres in order to exclude hazards to people, the plant and the environment.

In the decomposition part 3 ' It can come by partial decomposition of the product stream P to an accumulation of unreacted oxygen in partial streams, so that here again can give a critical composition. Such a composition should be avoided. According to the prior art, this z. B. by the use of washes, adsorbents or a targeted Abreaktion of unreacted O ₂ (see. US20100256432 ). However, this means additional investment and operating costs as well as a burden on the environment.

In the case of the catalyst K according to the invention, however, such additional apparatus can be omitted, in which the reactor device 1 is operated so that only minimal O ₂ concentrations are achieved at the reactor outlet.

This can also be used to operate a multistage reactor design, only small amounts of O ₂ are added in the in each stage, so that safe operation outside the relevant explosion areas is also possible here. This also promotes the selective formation of ethylene and suppresses the further oxidation to CO and CO2. Furthermore, the heat development can be safely controlled, as only in oxidation, ie in the presence of a corresponding amount of O ₂ , heat is released. In each further reactor stage is then again feeding a corresponding amount of O ₂ . Intermediate cooling can optionally be carried out between the reaction stages. In the limiting case, it may even be a reaction apparatus which has the appropriate staged O ₂ feed. Such process operation is possible only with a suitable robust catalyst K 'as provided by the present invention.

Example 6

To optimize oxidative dehydrogenation (eg, from ethane to ethene), it is desirable to achieve a very low concentration of O ₂ at the reactor exit. This means a low concentration of oxygen in the feed E for the reactor device 1 , However, this jeopardizes the stability of the MoVTeNbO _x catalysts in that this material undergoes reduction in the absence of O ₂ at the reaction temperature, which accompanies loss of the M1 structure and irreversible deactivation.

There were therefore different oxygen concentration in the reactor device 1 at 430 ° C and a pressure of 1 bar to determine a minimum O ₂ concentration, which can be used in the ODH without the stability of the catalyst K 'too strong to affect. In the in the 3 Measured for 2 hours at 430 ° C with decreasing O ₂ concentration, starting from an initial value of 9.1% mol (molar ratio 1: 1 with respect to ethene) to 1% mol.

4 in this case shows on the lower abscissa D, the time in hours and on the upper abscissa G, the O ₂ concentration at the inlet of the reactor device (mol%), where plotted on the ordinate F, the conversion of O ₂ or C ₂ H ₆ in% is. The total flow was maintained at 33 mL / min for 300 mg of catalyst K 'and the feed composition (E) was 9.1 mol% C ₂ H ₆ , x mol% O ₂ and the balance He (100 - 9.1 - x% mol). After each measurement, the O ₂ concentration was again increased to the initial value for 2 hours (9.1 mol% O ₂ ) to verify that no deactivation of the MoVTeNbO _x catalyst had taken place. Under these conditions, it has been observed that the conversion of O ₂ can reach a maximum of 90% without causing irreversible catalyst reduction.

5 on the lower abscissa the D shows the time in hours and on the upper abscissa G 'the O ₂ concentration at the reactor inlet (mol%), where on the ordinate F the yield of CO, CO ₂ and C ₂ H ₄ in % is applied. It becomes clear that in particular at 4 mol% O ₂ in use E, in which the O ₂ content at the outlet of the reactor device 1 at 0.5% mol, no significant deactivation of the catalyst K 'after 80 hours at 90% O ₂ conversion could be found.

As a result, this shows the robustness of a catalyst K 'optimized by the aftertreatment according to the invention, which advantageously has an operation under low oxygen concentrations at the outlet of the reactor device 1 allows.

Example 7

A gas stream of 24.63 Nl / h consisting of 81.8 vol .-% N ₂ , 9, 1 vol .-% 0 ₂ and 9.1 vol .-% ethane is a catalyst bed (length 72 mm) consisting of 4.0 g of a MoVaTe invention _b NbcO _x catalyst K ', which was aftertreated with steam, and from 22.7 g of inert material (balls of glass shot, diameter about 2 mm) passed, which is located in an electrically tempered tubular reactor. The pressure is varied between 1 and 5 bar at a temperature of 370 ° C and 400 ° C. The product gas is cooled by means of a heat exchanger with water cooling and then the composition analyzed by gas chromatography. This results in the conversions and selectivities that can be seen and calculated from the following Table 5. Table 5 temperature 1.0 barg 2.5 barg 5.0 barg 370 ° C Ethane turnover [%] 20.94 32,99 37.91 Ethene selectivity [%] > 99% 96.23 89.12 Ethene yield [%] 21.61 31.74 37.91 400 ° C Ethane turnover [%] 37.18 50.87 61.95 Ethene selectivity [%] 92.86 87.22 77.72 Ethene yield [%] 34.53 44.37 48.14 reference numeral 1 reactor means 2 separators 3 CO ₂ removal 3 ' disassembling part 4 inert 5 . 6 . 7 Purge 8th . 9 . 12 Heat exchanger 10 oxidant 11 Steam V Diluent, z. As water vapor e commitment e ' Ethan P product flow K Catalyst (untreated) K ' Catalyst aftertreated

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 20100256432 [0008, 0086]
• US 2005085678 [0009]
• WO 2010096909 [0009]
• US2001025129 [0009]
• US 4899003 [0009]
• US 4739124 [0009]
• WO 2005060442 A2 [0010]
• WO 2010115108 A1 [0010]
• WO 2010115099 A1 [0010]
• DE 112009000404 T5 [0011]

Cited non-patent literature

• K. Amakawa et al. in ACS Catalysis, 2013, 3, 1103-1113 [0003]
• DeSanto, P., Jr., et al., Structural aspects of the M1 and M2 phases in MoVNbTeO propane ammoxidation catalysts. Journal of Crystallography, 2004. 219 (3): p. 152-165 [0003]
• F. Cavani et al., Catalysis Today 2007, 127, 113-131 [0004]
• P. Botella, E. Garcia-Gonzalez, A. Dejoz, JM Lopez-Nieto, MI Vazquez, J. Gonzalez-Calbet, "Selective Oxidative Dehydrogenation of Ethanes on MoVTeNbO Mixed Metal Oxide Catalysts", Journal of Catalysis 225 (2004), 428-438 [0004]
• F. Ivars, P. Botella, A. Dejoz, JM Lopez-Nieto, P. Concepcion, MI Vazquez, "Selective Oxidation of Short-Chain Alkanes over Hydrothermally Prepared MoVTenBo Cataylsts", Topics in Catalysis 38 (2006), 59-67 [0004]
• Catalysis Today 2004, 91-92, 241-245 [0004]
• Catalysis Today 2010, 157, 291-296 [0004]
• C. Gärtner, AC van Veen, JA Lercher, ChemCatChem 2013, 5, doi: 10.1002 / cctc.201200966 [0004]
• R. Schlögl, Topics Catalysis 2011, 54, 627-638 [0005]
• EM Thorsteinson, TP Wilson, FG Young, PH Kasai (Journal of Catalysis 52 (1977), 116-132) "The Oxidative Dehydrogenation of Ethane over Catalysts Containing Mixed Oxides of Molybdenum and Vanadium" [0006]

Claims (15)

A process for producing a catalyst, wherein a catalyst is provided in the form of a metal oxide catalyst having at least one element selected from Mo, Te, Nb, V, Cr, Dy, Ga, Sb, Ni, Co, Pt and Ce characterized in that the catalyst (K) is subjected to an after-treatment to increase the proportion of the M1 phase of the catalyst (K), the catalyst (K) to produce a post-treated catalyst (K ') with steam at a pressure below 100 bar , preferably below 80 bar, preferably below 50 bar, is brought into contact, and / or - brought into contact with oxygen. A method according to claim 1, characterized in that the catalyst (K) in the after-treatment at a temperature of at least 200 ° C, preferably at a temperature of at least 350 ° C, preferably at a temperature of at least 400 ° C, preferably at a temperature in the range of 200 ° C to 650 ° C, preferably at a temperature in the range of 300 ° C to 650 ° C, preferably at a temperature in the range of 350 ° C to 600 ° C, preferably at a temperature in the range of 350 ° C to 550 ° C, preferably at a temperature in the range of 350 ° C to 400 ° C, preferably at a temperature in the range of 400 ° C to 500 ° C, is brought into contact with the water vapor and / or oxygen. Process according to Claim 1 or 2, characterized in that the catalyst (K) is a metal oxide catalyst comprising the elements Mo, V, Te, Nb. A method according to claim 1 or 2, characterized in that the catalyst is a catalyst of the form MoV _a Te _b Nb _c O _x , wherein a in the range of 0.05 to 0.4, preferably 0.12 to 0 , 25, and wherein b is in the range of 0.02 to 0.2, preferably 0.04 to 0.1, and wherein c in the range of 0.05 to 0, 3, preferably 0.1 to 0 , 18, lies. Method according to one of the preceding claims, characterized in that the catalyst (K) in the after-treatment for a period of at least one hour, in particular for a period of time in the range of one hour to one week, in particular for a period in the range of one hour to 24 hours, with which water vapor is brought into contact. Method according to one of the preceding claims, characterized in that the catalyst (K) in the after-treatment for a period of at least one hour, in particular for a period in the range of one to five hours, in particular for a period in the range of one to two hours , is brought into contact with the oxygen. Method according to one of the preceding claims, characterized in that the catalyst (K) in the aftertreatment with the steam and / or oxygen at a pressure in the range of 0.5 bar to 100 bar, preferably 0.5 bar to 90 bar, preferably 0.5 bar to 80 bar, preferably 0.5 bar to 70 bar, preferably 0.5 bar to 60 bar, preferably 0.5 bar to 50 bar, preferably 0.5 bar to 40 bar, preferably 0.5 bar up to 30 bar, preferably 0.5 bar to 20 bar, preferably 0.5 bar to 10 bar, preferably 0.5 bar to 5 bar, preferably 0.5 bar to 4 bar, preferably 0.5 bar to 3 bar, preferably 0.5 bar to 2 bar, preferably 0.5 bar to 1.5 bar, preferably 0.8 bar to 1.2 bar, preferably 0.9 bar to 1.1 bar, preferably at a pressure of 1 bar, in Contact is brought. Method according to one of the preceding claims, characterized in that the catalyst (K) in the after-treatment with a mixture comprising water vapor and oxygen is brought into contact, or that the catalyst during the aftertreatment in any sequence, in particular alternately, with water vapor or oxygen is brought into contact. Method according to one of the preceding claims, characterized in that the catalyst (K) is brought into contact with the oxygen in the after-treatment by oxygen to the catalyst (K) - in the form of pure oxygen, - in the form of air, in particular synthetic air , in particular oxygen-enriched or oxygen-depleted air, or - in the form of a mixture comprising oxygen and another gas, in particular from the group He, Ar and N, is supplied, wherein oxygen is present in the mixture, in particular with a concentration of at least 10 vol .-% , Method according to one of the preceding claims, characterized in that the oxygen for the post-treatment of the catalyst (K) is generated by means of pressure swing adsorption. Catalyst, in particular for oxidative dehydrogenation, prepared by a process according to one of Claims 1 to 10. A process for oxidative dehydrogenation, which comprises the process according to any one of claims 1 to 10, wherein a feed stream (E) comprising an alkane, in particular ethane, in a reactor device ( 1 ) is fed to the post-treated catalyst (K '), wherein an alkene-containing product stream (P) is produced by oxidative dehydrogenation of the alkane with oxygen in the presence of the post-treated catalyst (K'). A method according to claim 12, characterized in that the catalyst (K) outside the reactor device ( 1 ) is subjected to the post-treatment and then into the reactor device ( 1 ) or that the catalyst (K) in the reactor device ( 1 ) is subjected to the aftertreatment. A method according to claim 12 or 13, characterized in that the catalyst (K, K ') is diluted with an inert material, wherein in particular the catalyst (K, K') is diluted before or after the post-treatment with the inert material. Method according to one of claims 12 to 14, characterized in that a diluent (V) in the reactor device ( 1 ), which is inert or has at least one inert component, in particular to control the heat of reaction in the oxidative dehydrogenation of the alkane, in particular to prevent an explosion in the oxidative dehydrogenation of the alkane, in particular as diluent one of the following substances or a Combination of several of the following substances is used: - water vapor, - nitrogen, - air.

Images