EP2054358A1

EP2054358A1 - Use of a catalyst based on zeolites in the conversion of oxygenates to lower olefins, and associated method

Info

Publication number: EP2054358A1
Application number: EP07765300A
Authority: EP
Inventors: Arno Tissler; Rainer Albert Rakoczy; Roderik Althoff
Original assignee: Sued Chemie AG
Current assignee: Sued Chemie IP GmbH and Co KG
Priority date: 2006-08-08
Filing date: 2007-05-31
Publication date: 2009-05-06
Also published as: RU2009108303A; CN101500966A; US20090326299A1; ZA200900504B; WO2008017529A1; DE102006037314A1; CN101500966B; RU2422418C2

Abstract

The invention relates to the use of a catalyst based on crystalline aluminosilicates for the conversion of oxygenates to lower olefins, the catalyst having an SiO2/Al2O3 molar ratio of 20 to 200 and being modified with 0.1% to 10% by weight of readily oxidant metal (calculated as the corresponding metal oxide) and/or with 0.05% to 5% by weight of cerium (calculated as Ce2O3), and also to an associated method.

Description

Use of a catalyst based on zeolites in the reaction of oxygenates to lower olefins and processes for this purpose

The present invention relates to the use of a catalyst based on crystalline aluminosilicate which is modified with a readily oxidizing metal and / or cerium in the reaction of oxygenates, such as methanol, ethanol, dimethyl ether or diethyl ether, to lower olefins, such as propylene, as well as a corresponding method.

A typical conversion reaction for the use according to the invention and the process according to the invention is described by the following equation:

H ₃ C-OH -H ₂ O

CH ₃ OCH ₃ →. C, = or C ₉ = H ₃ C-OH + H ₂ O.

For the first step, the equilibrium reaction, a conventional dehydrogenation catalyst, for example γ-alumina, or else a catalyst described in the context of the present invention can be used as a so-called upstream catalyst. In principle, the reaction of the methanol and / or dimethyl ether vapor and steam-containing reaction mixture in a tubular reactor may take place on an indirectly cooled catalyst, such as in EP 0 448 000 A1, which is incorporated by reference into the disclosure of the present invention should, is described. In particular, the method described in line 28 on page 6 to line 8 on page 7 of EP 0 448 000 A1 is used in the context of the present invention, wherein the catalyst described in the context of this invention is used.

In the second step, the reaction reaction to olefins, on the one hand finds the catalyst described in the context of the present invention application; On the other hand, other zeolite-based catalysts can be used. Fundamentally suitable catalysts based on crystalline aluminosilicates of the pentasil type are known from the prior art.

For example, EP 1 424 128 A1 discloses such a catalyst, which is composed of primary crystallites having an average diameter of at least 0.01 μm and less than 0.1 μm and at least 20% to agglomerates of from 5 to 500 μm are united, wherein the primary crystallites or agglomerates are connected by finely divided aluminum oxide, whose BET surface area is 300 to 600 m ² / g and whose pore volume is 0.3 to 0.8 cm ³ / g, in the H-form is present and in which the amount of finely divided alumina binder 10 to 40 wt .-%, based on the total weight of aluminosilicate and binder, wherein the finely divided alumina binder is present in the reaction mixture as a peptizable alumina hydrate, wherein as the aluminum and alkali source sodium aluminate is used and the primary synthesis of the crystalline aluminosilicate takes place without acid addition.

Furthermore, EP 0 369 364 A2 discloses such a catalyst having an Si / Al atomic ratio of at least 10, which is composed of primary crystallites with an average diameter of at least 0.1 μm and at most 0.9 μm, which are partially combined to give agglomerates, wherein the primary crystallites or agglomerates are interconnected by finely divided aluminum oxide, which is obtainable by hydrolysis of organoaluminum compounds, whose BET surface area is 300 to 600 m ² / g and whose pore volume is 0.3 to 0.8 cm ³ / g is.

A disadvantage of these and other zeolite catalysts is that they tend to reversible coking or for irreversible dealumination, resulting in a diffusion inhibition of the catalytic reaction or to reduce the intrinsic activity to the complete deactivation of the catalyst.

To revise the coking, the catalyst must be regenerated at regular intervals. This regeneration is carried out at temperatures between 500 and 800 ° C and damages the zeolite catalyst in addition to the already running under normal reaction conditions slow deactivation. Furthermore, the repeated regeneration shortens the cycle times and thus worsens the effectiveness of the catalyst.

In irreversible dealumination, the catalyst is damaged by the high water vapor content of the process gas and by the high reaction temperature, more precisely dealuminated, and thus deactivated.

EP 0 955 080 A1 discloses a zeolite-based catalyst exclusively for the removal of nitrogen oxides from exhaust gases containing oxygen and water, which contains at least one metallic catalytic component, for example iron, and a process for its preparation. The object of the present invention is to provide a catalyst which is suitable for the conversion of oxygenates to lower olefins and which has a slower rate of coking and a reduced degree of thermal dealumination in the context of this reaction.

Surprisingly, this object is achieved by the use of a catalyst modified with a slightly oxidizing metal and / or cerium based on crystalline aluminosilicates, preferably of the pentasil type, in the reactions mentioned at the outset.

The introduction of slightly oxidizing metals, for example iron, manganese, chromium or cobalt, in particular iron, surprisingly in the presence of water vapor, as it is present in the reactions mentioned above, that the coke formed under the reaction conditions partially oxidized again is, without oxidizing the educts or products in turn. This extends the time until the necessary regeneration.

The introduction of cerium surprisingly leads to a significant increase in the remaining active sites in the case of a hydrothermal deactivation (dealumination). For example, an increase by a factor of 2 to 3 is observed. The number of possible regeneration cycles thus increases by a comparable factor.

If both a slightly oxidizing metal, such as iron, manganese, chromium or cobalt, and cerium in a zeolite catalyst, for example of the pentasil type, are introduced, there is a synergistic effect in the conversion of oxygenates to lower olefins results in both an extended cycle time and an increased cycle count.

The introduction of one or more further metals from the group Zr, Ag, W, La and Th in zeolite catalysts leads to a further improvement of the reaction. For example, a combination of cerium and zirconium exhibits a synergistic effect on the catalytic reaction, and a combination of iron and silver has a synergistic effect on the hydrothermal stability of the catalyst. Usually zeolites are used in the prior art for the described reaction reaction of oxygenates to lower olefins, which have a SiO ₂ / Al ₂ O ₃ - module (ie a molar ratio) of greater than 100. These zeolites are hydrothermally more stable than those with a lower SiO ₂ / Al ₂ O ₃ modulus, but have a lower starting activity. However, if zeolites with lower SiO ₂ / Al ₂ O ₃ modules are modified with a metal and / or cerium having a slightly oxidizing action, then these too show good stability, thus increasing the number of possible regeneration cycles. Consequently, zeolites with an SiO ₂ / Al ₂ O ₃ module range below 100 are also suitable for the present invention. A SiO ₂ / Al ₂ O ₃ molar ratio of from 20 to 200, particularly preferably from 40 to 200, is preferred here.

The zeolites which can be used for the invention have, for example, an average pore diameter of 0.5 to 1 nm, preferably 0.5 to 0.6 nm. Particularly preferred in the context of the present invention are zeolites of the pentasil type, which may have two different pore diameters, namely 0.54 and 0.57 nm. The pore diameters are determined crystallographically.

Zeolites which can be used for the invention have from 0.1 to 10% by weight, preferably from 0.5 to 2% by weight, of easily oxidizing metal (calculated as the corresponding metal oxide) and / or from 0.05 to 5 wt .-%, preferably 0.1 to 1 wt .-% cerium (calculated as Ce ₂ O ₃ ) on. Iron is preferred as the lightly oxidizing metal, with the weight percentages then referring to Fe ₂ O ₃ . These and other weight percentages given in the context of the present invention are based on the total weight of all solids, unless stated otherwise in the individual case.

The catalysts which can be used for the invention may additionally contain from 0.1 to 1% by weight, preferably from 0.1 to 0.5% by weight, of one or more metals of the group consisting of Zr, Ag, W, La and Th to be modified.

The basis for the catalysts which can be used in the context of the invention are described, for example, in EP 1 424 128 A1 and EP 0 369 364 A2. However, it is also possible to use other commercially available zeolites, in particular of the pentasil type, for the preparation of these catalysts.

In any case, the obtained or commercially available zeolite catalysts must still be modified with at least one readily oxidizing metal and / or cerium to be suitable for the invention. This modification can basically over Solid-state ion exchange, liquid ion exchange with aqueous metal salt solutions or by impregnation.

For solid-state ion exchange, for example, the process described and claimed in EP 0 955 080 A1 is suitable. Specifically, this includes the following steps:

(A) incorporation of iron and / or cerium and optionally Zr, Ag, W, La and / or Th in a synthetic zeolite material, whereby a dry mixture of the following components is prepared:

Component 1, consisting of ammonium salts, NH ₃ / NH ₄ zeolites or N-containing compounds,

Component 2, consisting of highly silicate zeolite structures with a SiO ₂ -Al ₂ O ₃ ratio of 20 to 200, Component 3 an active component selected from a compound of the aforementioned group of active components,

(B) mixing the components 1, 2 and 3 in a mill under normal pressure and normal temperature and

(C) tempering at a temperature of at least 300 ° C until the ion exchange is complete,

(D) Cool to room temperature.

The incorporation of iron in the zeolite by solid-state ion exchange is also in the magazines Studies in Surface Science and Catalysis 69, page 1641-1645 (1991) for zeolite Y and Studies in Surface Science and Catalysis 94, page 665-672 for zeolites ZSM-5 described. In the method of solid-state ion exchange, mixtures of the NH ₄ and / or H form of the zeolite and an iron salt are prepared mechanically by intensive mechanical mixing in a ball mill at room temperature to produce the Fe zeolites. Thereafter, this mixture is calcined in a chamber furnace in air. After calcination, the Fe-ZSM-5 zeolites are washed thoroughly in distilled water and dried after filtering off the zeolite.

Basically, the following solid-state ion exchange method is applicable for the preparation of the catalysts used in the present invention:

(a) providing a crystalline aluminosilicate, preferably of the pentasil type; (t> 1) introduction of easily oxidizing metal and / or cerium into the aluminosilicate from step (a) by mixing the aluminosilicate with suitable compounds of the easily oxidizing metal and / or suitable cerium compounds; or (b2) introduction of easily oxidizing metal into the aluminosilicate from step (a) and subsequent introduction of cerium into the product obtained in the first substep or introduction of cerium into the aluminosilicate from step (a) and subsequent introduction of slightly oxidizing action Metal in the product obtained in the first partial step in each case by mixing with suitable compounds of the easily oxidizing metal or suitable cerium

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(b3) optionally introducing Zr, Ag, W, La and / or Th into the product obtained in step (b1) or (b2) by mixing with suitable compounds of Zr, Ag, W, La and / or Th; (c) heat treating or calcining the product obtained from step (b1), (b2) or (b3) (solid-state ion exchange step);

(d) combining the product of step (c) with 10 to 90% by weight (based on the total amount of ion-exchanged aluminosilicate) of a binder or a mixture of individual binders selected from the group consisting of: aluminum or silicon based binders , Alumina, alumina hydrate, SiO ₂ , TiO ₂ , WO ₃ or ZrO ₂ compounds; and

(E) temperature treatment of the product from step (d) at 400 to 700 ° C, preferably 450 to 600 ° C.

The preparation of crystalline aluminosilicate, preferably of the pentasil type, for step (a) is well known. For example, it can be represented by the methods in EP 1 424 128 A1 or EP 0 369 364.

The steps (b1) and (b2) are preferably carried out by grinding the aluminosilicate, preferably in its NH ₄ form, with FeCl ₂ .4H ₂ O or CeCl ₂ .7H ₂ O, preferably under reductive conditions.

The necessary amount of salt used of lightly oxidizing metal or of cerium is at least so much that the final product with 0.1 to 10 wt .-% slightly oxidizing metal (calculated as the corresponding metal oxide) and / or with 0.05 bis 5 wt .-% cerium (calculated as Ce ₂ O ₃ ) is modified. The preferred NH ₄ form of the zeolite is obtained from the Na or H form by treatment with dilute ammonium salt solution, preferably NH ₄ NO ₃ or (NH ₄ ) ₂ SO ₄ solution. For example, 10 to 100 g, preferably 20 to 80 g of salt per liter of water is used, wherein the zeolite for 1 to 12 hours, preferably 2 to 4 hours in this solution, for example, with stirring, at a temperature of 20 to 100 ° C, preferred 50 to 80 ° C is maintained. The zeolite content in the solution is for example 10 to 30 wt .-%, preferably 15 to 25 wt .-%.

Preferably, step (b3) is carried out by grinding the product of step (b1) or (b2) with the halogen salts, preferably the chlorides and / or nitrates, of the indicated metals, preferably under reductive conditions.

Further, step (c) is preferably carried out at 400 to 600 ° C for 1 to 100 hours, preferably under reductive conditions, preferably at an oxygen content below the oxygen content of air (eg, below 21% by volume and 23% by mass, respectively). An implementation of step (c) under protective gas, such as NH ₃ or H ₂ is also conceivable. For example, step (c) is carried out in a batch oven as part of a batch process, preferably using a well bed with a bed height of 5 to 20 cm. For example, working at a slight negative pressure, for example, 1 to 5% below the ambient pressure.

To increase the concentration of the desired ions in the zeolite, ie the easily oxidizing metal and / or the cerium and optionally the metals selected from the group consisting of Zr, Ag, W, La and Th, the steps (b1) or (b2) or (b3) and (c) are repeated.

In order to bring the product from step (c) into an appropriate form for the conversion of oxygenates to olefins, it is in step (d) with 10 to 90 wt .-%, preferably 15 to 30 wt .-% of an aluminum or Silicon based binder (based on the total amount of ion-exchanged aluminosilicate and binder) treated. Preferred binders or mixtures of individual binders are selected from the group consisting of: aluminum-based or silicon-based binders, aluminum oxide, aluminum oxide hydrate, SiO ₂ , TiO ₂ , WO ₃ or ZrO ₂ compounds. Also suitable are SiO ₂ or its precursors. Preference is further given to the primary crystallites or the agglomerates by means of finely divided aluminum oxide or SiO ₂ , which is preferably obtainable by hydrolysis of organoaluminum or organosilicon compounds, connected to each other.

The product obtained after step (d) is finally calcined in step (e) at 400 to 700 ° C, preferably 450 to 600 ° C to obtain a usable catalyst.

The liquid ion exchange to be used as an alternative is carried out by introducing, preferably stirring the aluminosilicate, preferably in its NH ₄ form, into an aqueous solution of a salt of the easily oxidizing metal, preferably an iron salt solution, preferably an FeSO ₄ solution or FeCl ₂ , or in an aqueous cerium salt solution, preferably in a Ce (SO ₄ ) ₂ solution. Suitable temperatures are in the range of 20 to 100 ° C, preferably from 50 to 80 ° C. Suitable concentrations of the salt solutions are in the range of 1 to 10 wt .-%, preferably 2 to 8 wt .-% total solids content. Suitable residence times are in the range of 1 to 12 hours, preferably 2 to 4 hours. A suitable zeolite content in solution is 10 to 30 wt .-%, preferably 15 to 25 wt .-%.

After the introduction of the metals by impregnation, aqueous ion exchange or by grinding with solid salts (solid-state ion exchange) and subsequent heat treatment, the catalyst material can be used, for example, either in pellet form, as an extrudate, as an extruded or coated honeycomb body.

The catalyst suitable for the invention is composed, for example, of primary crystallites having an average diameter of from 0.01 to 0.9 μm. These primary crystallites are, for example, at least 20% combined to form agglomerates of 5 to 500 μm, the primary crystallites or agglomerates being connected to one another by means of a binder based on aluminum or silicon. The primary crystallites preferably have an average diameter of from 0.01 to 0.06 μm, in particular from 0.015 to 0.05 μm.

The mean diameter of the primary crystallites is defined here as the arithmetic mean, averaged over a multiplicity of crystallites, between the largest and the smallest diameter of a single crystallite, determined by means of scanning electron microscopic investigations at a magnification of 80,000 (see below). This definition has its meaning in crystallites with an irregular Crystal habit, eg in rod-shaped crystallites. In the case of spherical or approximately spherical crystallites, the largest and the smallest diameter coincide.

The reported values for the primary crystallites are the average dimensions (arithmetic mean of the largest and the smallest dimension, averaged over a plurality of crystallites). These values are determined with a LEO Field Emission Scanning Electron Microscope (LEO Electron Microscopy Inc., USA) using powder samples of the catalyst which had previously been redispersed in acetone, sonicated for 30 seconds and then applied to a support (Sample Current Range: 4pA to 10nA). The measurement takes place at 80,000 times magnification. The values could be confirmed at 253,000 times magnification.

The BET surface area of the catalyst usable for the present invention is for example 200 to 600 m ² / g, preferably 250 to 400 m ² / g (determined according to DIN 66 131) and its pore volume (determined by mercury porosimetry according to DIN 66 133; Total pore volume) 0.3 to 0.8 cm ³ / g.

Further, the catalyst is preferably in the H form.

The invention further relates to a process for the catalytic production of lower olefins from oxygenates, wherein a catalyst is used which is based on crystalline aluminosilicate, preferably a pentasil-type zeolite, and

a SiO ₂ / Al ₂ O 3 molar ratio of from 20 to 200 and from 0.1 to 10% by weight of easily oxidizing metal (calculated as the corresponding metal oxide) and / or from 0.05 to 5% by weight of cerium (calculated as Ce ₂ Os).

The catalytic production of lower olefins from oxygenates is preferably carried out by reacting a mixture of oxygenate vapor and / or the vapor of the product and water vapor obtained by splitting off at least one molecule of water from at least two molecules of oxygenate and optionally additionally supplied water vapor in a tubular reactor on a indirectly cooled catalyst. In the case of methanol as an oxygenate, therefore, by splitting off a molecule of water from two molecules of methanol, dimethyl ether is firstly produced, which rather, subsequently converted to lower olefins using, for example, ethylene (C2 =) or propylene (C3 =) using the catalyst described in the present invention.

Particular embodiments of this method will become apparent from the corresponding dependent claims. The associated advantages have already been described above in the context of the use according to the invention.

The invention also relates to the use of a catalyst based on crystalline aluminosilicates having a SiO ₂ / Al ₂ O ₃ molar ratio of from 20 to 200, containing from 0.1 to 10% by weight of easily oxidizing metal (calculated as the corresponding Metal oxide) and / or with 0.05 to 5 wt .-% cerium (calculated as Ce ₂ O ₃ ) is modified in organic synthesis reactions with oxygenates as reactants and high water vapor concentrations, wherein in the synthesis reactions a water to oxygenate molar ratio of 0 , 5 to 10 is present. Preferably, in these reactions, there is a water to oxygenate mole ratio of 2 to 4. In the above-described reaction of methanol to dimethyl ether and finally to propylene or ethylene, for example, there is a water to oxygenate molar ratio of 4. The catalysts suitable for such reactions are those described above. A high water to oxygenate molar ratio is achieved, for example, by the addition of additional water vapor to the reactants.

The advantages of the catalysts described above in the context of the present invention will be apparent from the following examples and the figure.

FIG. 1 shows the desorption curves of NH ₃ at the H, Fe or Fe / Ce-modified zeolite of Example 1, aged at 800 ° C., 10% steam in air, 24 hours in a tube furnace.

Example 1: Modification of a zeolite with iron or iron and cerium

The pentasil type starting zeolite used was the Ammon-MFI type T 4480 from Süd-Chemie, Germany.

Modification with iron: In a ball mill one hour 1 kg starting zeolite together with 25 g of FeCl ₂ ^* 4 H ₂ O were long-milled at room temperature. The mixture was heated in a chamber oven in air from room temperature to 550 ° C in 3 hours and held there for 6 hours. After cooling the mixture, a modified zeolite with 1 wt.% Fe content, calculated as Fe ₂ C> ₃ , was obtained.

Modification with iron and cerium:

In a ball mill were taken one hour at room temperature for 1 kg starting zeolite together with 25 g of FeCl ₂ ^* 4 H ₂ O and 11, 7 milled 4 g CeCl ₃ ^* H ₂ O. The mixture was heated in a chamber oven in air from room temperature to 550 ° C in 3 hours and held there for 6 hours. After cooling the mixture, a modified zeolite having 1 wt% Fe content calculated as Fe ₂ O ₃ and 0.5 wt% cerium content calculated as Ce ₂ O _{3 was} obtained.

EXAMPLE 2 Detection of the Increased Hydrothermal Stability of the Zeolite from Example 1 Within the Present Invention (Compared to a Non-Metal-modified Zeolite)

From Fig. 1 it can be clearly seen that when using a Fe-modified zeolite better results are achieved, so there is a better hydrothermal stability, than when using the same zeolite in its H-form. In particular, in the case of Fe-modified zeolite, the adsorption band (marked by an arrow) is present in the range from about 380 to 400 ° C., whereas in the case of the H zeolite it is absent. However, this higher temperature band is the measure of the hydrothermal stability of the zeolite, as the zeolite is apparently still capable of adsorbing NH ₃ at these elevated temperatures.

Even better are the results using zeolites modified with both Fe and Ce. Here already at about 280 ° C a clear (marked by an arrow) Adsorptionsbande can be seen.

The partial pressure (mbar) of the mass 16, which was determined in a mass spectrometer from AMETEK combined with an absorption / desorption apparatus AMI 200 from Zeton / Altamira, is plotted on the Y axis of FIG. The corresponding temperature (° C) is indicated on the X-axis. To carry out the measurement, the sample is saturated after activation at 550 ° C in a helium stream at 1 10 ° C with NH ₃ and slowly heated to 750 ° C after flushing the excess NH ₃ and thereby desorbing NH ₃ with the mass spectrometer (mass 16) detected.

Claims

claims

1. Use of a catalyst based on crystalline aluminosilicates for reacting oxygenates to lower olefins, characterized in that the catalyst has a SiO ₂ / Al ₂ O ₃ molar ratio of 20 to 200 and 0.1 to 10 wt. % slightly oxidizing metal (calculated as the corresponding metal oxide) and / or with 0.05 to 5 wt .-% cerium (calculated as Ce ₂ Os) is modified.

2. Use according to claim 1, characterized in that the catalyst is additionally modified with 0.1 to 1 wt .-% of a metal of the group consisting of Zr, Ag, W, La and Th.

3. Use according to one of the preceding claims, characterized in that the crystalline aluminosilicate has an average pore diameter of 0.5 to 1 nm, preferably from 0.5 to 0.6 nm.

4. Use according to one of the preceding claims, characterized marked, that the aluminosilicate of the pentasil type.

5. Use according to one of the preceding claims, characterized in that the catalyst is obtainable by the following steps:

(a) providing a crystalline aluminosilicate, preferably of the pentasil type;

(b1) introduction of easily oxidizing metal and / or cerium into the aluminosilicate from step (a) by mixing the aluminosilicate with suitable compounds of the easily oxidizing metal and / or suitable cerium compounds; or (b2) introducing slightly oxidizing metal into the aluminosilicate

Step (a) and subsequent introduction of cerium into the product obtained in the first substep or introduction of cerium into the aluminosilicate from step (a) and subsequent introduction of slightly oxidizing metal into the product obtained in the first substep, in each case by mixing suitable compounds of the easily oxidizing metal or suitable cerium compounds; and (b3) optionally introducing Zr, Ag, W, La and / or Th into the product obtained in step (b1) or (b2) by mixing with suitable compounds of Zr, Ag, W, La and / or Th;

(c) heat treating or calcining the product obtained from step (b1), (b2) or (b3) (solid-state ion exchange step);

(d) combining the product of step (c) with 10 to 90% by weight (based on the total amount of ion-exchanged aluminosilicate) of a binder or mixture of individual binders selected from the group consisting of: aluminum or silicon based binders - alumina, alumina hydrate, SiO ₂ -, TiO ₂ -, WO ₃ - or ZrO ₂ -

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6. Use according to one of the preceding claims, characterized in that iron (Fe) is used as lightly oxidizing metal (calculation of wt .-% - information as Fe ₂ O ₃ ).

7. Use according to one of the preceding claims, characterized marked, that the oxygenate methanol and / or dimethyl ether and the lower olefin

Propylene and / or ethylene is.

8. A process for the catalytic production of lower olefins from oxygenates, characterized in that a catalyst is used which is based on crystalline aluminosilicate and has a SiO ₂ / Al ₂ O ₃ molar ratio of 20 to 200 and 0.1 to 10 wt .-% slightly oxidizing metal (calculated as the corresponding metal oxide) and / or 0.05 to 5 wt .-% cerium (calculated as Ce ₂ O ₃ ) contains.

9. The method according to claim 8, characterized in that the oxygenate is methanol and / or dimethyl ether and the lower olefin is propylene and / or ethylene.

10. The method according to claim 8 or 9, characterized in that the catalyst is additionally modified with 0.1 to 1 wt .-% of a metal of the group consisting of Zr, Ag, W, La and Th.

1 1. The method according to any one of claims 8 to 10, characterized in that the crystalline aluminosilicate has an average pore diameter of 0.5 to 1 nm, preferably from 0.5 to 0.6 nm.

12. The method according to any one of claims 8 to 11, characterized in that the crystalline aluminosilicate of the pentasil type.

13. The method according to any one of claims 8 to 12, characterized in that the catalyst is obtainable by the following steps:

(a) providing a crystalline aluminosilicate, preferably of the pentasil type;

(b1) introduction of easily oxidizing metal and / or cerium into the aluminosilicate from step (a) by mixing the aluminosilicate with suitable compounds of the easily oxidizing metal and / or suitable cerium compounds; or

(b2) introduction of slightly oxidizing metal into the aluminosilicate from step (a) and subsequent introduction of cerium into the product obtained in the first substep or introduction of cerium into the aluminosilicate from step (a) and subsequent introduction of slightly oxidizing action

Metal in the product obtained in the first step in each case by mixing with suitable compounds of the easily oxidizing metal or suitable cerium compounds; and

(b3) optionally introducing Zr, Ag, W, La and / or Th into the product obtained in step (b1) or (b2) by mixing with suitable compounds of Zr, Ag, W, La and / or Th;

(d) combining the product of step (c) with 10 to 90% by weight (based on the total amount of ion-exchanged aluminosilicate) of a binder or a mixture of individual binders selected from the group consisting of: aluminum or silicon based binders Alumina, alumina hydrate, SiO 2, TiO 2, WO 3 or ZrO 2 compounds; and (e) heat treating the product of step (d) at 400 to 700 ° C, preferably 450 to 600 ° C.

14. The method according to any one of claims 8 to 13, characterized in that is used as lightly oxidizing metal iron (Fe) (calculation of wt .-% - information as Fe ₂ O ₃ ).

15. Use of a catalyst based on crystalline aluminosilicates having a SiO ₂ / Al ₂ O ₃ molar ratio of from 20 to 200, containing from 0.1 to 10% by weight of easily oxidizing metal (calculated as corresponding metal oxide) and / or in 0.05 to 5 wt .-% cerium (calculated as Ce ₂ O ₃ ) is modified, in organic synthesis reactions with oxygenates as starting materials and high water vapor concentrations, wherein in the synthesis reactions a water to oxygenat-

Molar ratio of 0.5 to 10 is present.