DE19608660A1 - Process for the preparation of epsilon-caprolactam - Google Patents

Abstract

Prodn. of iota -caprolactam (I) comprises Beckmann rearrangement of cyclohexanone oxime (II) in the gas phase at 250-450 deg C on catalysts (III) consisting of MFI-zeolites with surface OH gps. in a symmetrical orientation towards one another due to the absence of central metal atoms. Also claimed are (i) a process for the prodn. of (III); and (ii) a process for regenerating (III) by treatment with pure nitrogen at 400-650 deg C.

Description

The invention relates to an improved method for Preparation of ε-caprolactam from cyclohexanone oxime in the Gas phase using MFI catalysts, on whose Surface symmetrically arranged OH groups are located.

As a starting point for the nylon 6 synthesis is ε-caprolactam of high economic importance. in the Nowadays mostly used classical manufacturing Cyclohexanone oxime is carried out on fuming sulfuric acid by Beckmann rearrangement to ε-caprolactam implemented. A disadvantage of this method is the Neutralization of sulfuric acid necessary use of Ammonia, with an ammonium sulfate attack of up to 4.5 t per t caprolactam is connected. To this undesirable Byproducts have been avoided since the mid-sixties Years of effort, the reaction heterogeneous to carry out catalytically.

It is known that ε-caprolactam from cyclohexanone oxime in the gas phase on solid catalysts, for example Zeolites with MFI structure can be produced.

X and Y zeolites and mordenites in the H form or doped with rare earth metals or transition metals deactivate extremely fast. On these catalysts 5-cyanopent-1-ene, cyclohexanone and cyclo are reinforced hexanol formed as by-products. As a process parameter Temperatures below 400 ° C were atmospheric pressure proposed. Furthermore, non-polar solvents should be used such as cyclohexane, benzene or toluene be more advantageous than more polar solvents.  

The partial blockage of the acidic centers of the HY zeolites with Na did not improve the Results [M. Burquet et al., An. Quim. Ser. A 81 (1985) 259; A. Aucejo et al., Appl. Catal, 22 (1986) 187 and A. Corma et al. Zeolites 11 (1991) 593]. Rather, ask the authors noted that strong for the Beckmann rearrangement acid brönsted acidic centers with pKa 1.5 are necessary and that the selectivity-reducing by-product is 5-cyano pent-1-ene both at the acidic sites and at the Na + Ions is formed. Furthermore, the authors suspect that the deactivation of the zeolite catalyst by basic By-products such as aniline and methylpyridine take place and not by coke formation on the catalyst surface, since after the reaction, the color of the catalyst is still nearly is white.

To the disadvantages of rapid aging of the X and To avoid Y zeolite catalysts were pentasil zeolites (MFI structure).

In the patents EP 0 494 535 and EP 0 544 530 are also considered zeolites with MFI structure as favorable. However, here it becomes a high Si / M ratio of 5 to above 500, with the metal for Al, B, Ga under other things can stand. As additional components or solutions Medium is called alcohols and ethers and water. The maximum water addition is 0.06-2.5 moles per mole Oxime.

The attempts to improve the service life of the catalyst also went in the direction that one the outer surface a boron MFI zeolite covered with Na ions, so the To neutralize acidity on the outer surface [EP 0 086 543 (7.5.1986) Stamicarbon]. A mix of Cyclohexanone oxime, toluene, carbon dioxide and water in molar ratio 1: 3: 7: 1 at 340 ° C, the cyclo Hexanonoxim reacted quantitatively on this catalyst. The selectivity for ε-caprolactam is given as 58%.  

The lifetime of the Na-ion treated catalyst is 15 hours and is more than 3 times as long as on untreated boron MFI zeolite. Also on this Catalyst becomes strong byproduct 5-cyanopent-1-ene formed and thus does not represent a satisfactory result.

The object of the invention is the process for the preparation of ε-caprolactam by the Beckmann rearrangement in the Gas phase using modified zeolites of the MFI type as catalysts to improve.

The invention relates to a process for the preparation of ε-caprolactam by Beckmann rearrangement of cyclohexa Nonoxime in the gas phase in the temperature range from 250 to 450 ° C of zeolite catalysts characterized is that one uses MFI zeolites, which at the surface due to the absence of central metal atoms such as Si, Al and B have OH groups that are symmetrical to each other are arranged.

Crystalline silicates with MFI structure are long gone known in the art. On the one hand you can only be constructed of SiO₄ tetrahedra, on the other side However, in the majority of aluminosilicates to count or silicates in which other metal atoms instead of the aluminum present in the lattice framework.

The first synthesis of an aluminosilicate with MFI structure is published in US Patent 3,702,886, where there the Designation "Zeolite ZSM-5" was selected. He became the Labeling classified as pentasil zeolite. The use areas are in the field of catalysis, the Molecular sieves or as a drying agent. The together Substitution of this zeolite class can be as follows describe:

0.9 ± 0.2 M _{2 / n} O: Al₂O₃: 5 - 100 SiO₂: zH₂O

where M is a cation, n is the charge of this cation and z is a number between 0 and 40. The making of this Type of catalyst is carried out in a hydrothermal synthesis. To It is usually a silicon source with an aluminum source in the presence of water and the template Tetrapropylammonium hydroxide dissolved and in an autoclave under stirring or static conditions Crystallization brought.

Suitable synthesis conditions cause an isomorphic Substitution of aluminum or silicon. Such scaffolding substituted zeolites with MFI structure for Example trivalent and divalent elements, such as B, Ga, Fe, Cr, Be, As, Sb and Bi in place of the aluminum or tetravalent elements such as Ge, Ti, Zr, Hf instead of silicon.

The catalytic properties of this material in the in general by exchanging the sodium ions for Example protons or metal cations.

A particular embodiment of zeolite production consists of an alkali-free synthesis. The aluminosilicate zeolite can be made, for example, from an aluminum compound, preferably Al (OH) ₃ or Al₂ (SO₄) ₃, and a silicon component, preferably fumed silica in aqueous amine solution, in particular 1,6-hexanediamine or 1,3-propanediamine or triethylenetriamine solution with and without alkali or Erdalkalizusatz at 100 to 200 ° C below autogenous pressure. The thus obtained Aluminosilicates contain depending on the choice of the starting material Amounts a SiO₂ / Al₂O₃ ratio of 10 to 40,000. Such preparations are described for example in EP 0 007 081. The aluminosilicate zeolites can also be obtained in ethereal medium such as diethylene glycol dimethyl ether or 1,4-butanediol or in water produce.  

The borosilicate zeolite may be, for example, at 90 to 200 ° C be synthesized under autogenous pressure by adding a Boron compound, for example H₃BO₃, with a silicon compound, preferably fumed silica, in aqueous amine solution, especially in 1,6-hexanediamine or 1,3-propanediamine or triethylenetetramine solution with and in particular without alkali or alkaline earth metal addition to the reaction brings. This is described, for example, in EP 0 007 081. You can in this reaction instead of an aqueous amine Solution an ethereal solution, for example with diethylene glycol dimethyl ether, or an alcoholic solution, for Example with 1,6-hexanediol, use as solvent.

The iron silicate zeolite is obtained for example from a Iron compound, preferably Fe₂ (SO₄) ₃ and a silicon compound, preferably also fumed silica, in aqueous amine solution, in particular 1,6-hexanediamine, with and without alkali or alkaline earth at 100 to 200 ° C. under autogenous pressure, as for example in EP 0 007 081 described.

Particularly preferred are alumino-, boro- and iron silicate zeolites of the pentasil type, as well as those described in DE-OS 30 06 471, EP 0 034 727 and EP 0 046 504 are isotactic Zeolites.

The molecular sieves thus produced can according to their Isolation, drying at 100 to 160 ° C, preferably 110 ° C, and calcination at 450 to 600 ° C, preferably 550 ° C, with a binder in the ratio 90: 10 to 40: 60 wt .-% to strands or tablets are deformed. Suitable binders are various aluminas, preferably boehmite, amorphous aluminum silicates with a SiO₂ / Al₂O₃ ratio of 25: 75 to 95: 5, preferably 75: 25, silica, preferably fumed SiO₂, Mixtures of highly dispersed SiO₂ and highly dispersed Al₂O₃, highly dispersed TiO₂ and clay. After deformation will be  the extrudates or pellets dried at 110 ° C / 16 h and calcined at 550 ° C / 6 h.

Particularly advantageous such catalysts by preparing the isolated molecular sieve deformed immediately after drying and first after the Deformation of a calcination subjects. The molecular but sieves can also be used in pure form, without binders, as Strands or tablets are used. This deformation occurs with the addition of distension or peptization such as methyl cellulose, hexaethyl cellulose, oxalic acid, nitric acid, ammonia, amine, Silicoester, graphite or mixtures thereof. Out of that too Strands of deformed zeolites can be prepared by grinding and Seven obtained the desired catalyst particle size. Particle sizes are suitable for use in fluidized beds between 0.1 and 0.6 mm, in fixed beds become particles sizes between 1 to 5 mm, in liquid phase Batch reactors are preferably used powder.

The particular suitability of the MFI invention used Zeolites arises because of a known per se Manufacturing process following aftertreatment. These causes on the inner and outer surface of the Zeolites symmetrically arranged "nests" of OH groups arise.

By a suitable treatment, Si or others become Metal atoms such as B, Fe, Ga from the oxide crystal lattice removed, with the released in this way Oxygen bonds are saturated by hydrogen ions become. The use of borosilicate zeolites is preferred as a precursor.

If it is a trivalent element, for example B, which is released, also arise symmetrically arranged silanol groups according to the following drawing

The hydrogen bonded OH groups The "nests" can be, for example, by FT-IR sub to prove these.

However, the formation of silanol nests is not alone Borzeolith limited.

The geometric arrangement as well as the weak acid Behavior of the four silanol groups on the surface of the Zeolite crystals surprisingly has a special effect favorable for the rearrangement of cyclohexanone oxime to ε- Caprolactam in the gas phase.

The suitable crystallite size for the inventive Method is <5 microns, preferably <2 microns, in particular <1 μm. A range of 0.05-0.5 microns proves to be extremely advantageous.

Is it highly silicious MFI zeolites such as Example silicalites with monoclinic structure, so this is by a basic treatment at higher temperatures in transformed the orthorhombic structure. The structure Conversion can be done, for example, with X-ray diffractometry be detected.

For this purpose, the catalyst is, for example, in a stirred flask or in an autoclave under autogenous pressure at a Temperature of 20 to 150 ° C, preferably 60-150 ° C, with a solution of ammonium salts (nitrate, chloride) and / or aqueous ammonia solution brought into contact. Subsequently The catalyst thus obtained is at 110 ° C / 12 hours  dried. One then receives an orthorhombic crystal structure with the described active hydroxyl.

For boron-containing MFI zeolites is an essential Possibility of modification in that one the zeolitic material - deformed or undeformed - one Treatment with acids such as hydrochloric acid, hydrofluoric acid, phosphorus acid and / or water vapor exposes. This one goes to Example so that zeolites in powder form with 0.5 to 3 n phosphoric acid for 0.5 to 10 hours at 40 to 100 ° C. treated. After the treatment is washed with water, dried at 80 to 100 ° C for 0.5 to 10 h and at 350 to Calcined at 650 ° C for 1 to 10 hours. After another The procedure is to treat zeolites before or after their Deformation with binders, for example, 1 to 3 hours at temperatures of 60-80 ° C with a 3- to 25 wt .-%, in particular 12-20 wt .-%, aqueous Hydrochloric acid. Subsequently, the thus treated zeolite with Washed water, dried and at 400-500 ° C. calcined.

A preferred modification of the MFI zeolites is after described below.

If the zeolitic powder is treated with steam, is it expedient, at a temperature of 300-650 ° C, completely more preferably 400-500 ° C, over a period of 0.5-3 hours, preferably 1-2 hours, to work and a mixture of nitrogen or air and water vapor with a water vapor partial pressure of 0.01-1 bar, preferably 0.05-0.8 bar, most preferably from 0.1-0.5 bar, to use. This treatment can become an acid Treatment with, for example, aqueous hydrochloric acid with a pH between 4-6, preferably 5-6, connect. The so treated zeolite is washed with water and at 110 ° C / 16 hours dried.  

Another preferred embodiment is the calcination of Zeolites under oxygen at a temperature of 450-600 ° C, preferably at 500-550 ° C, especially if one of Boron and Fe zeolites go out. Here is a Demetallierung or expelling the elements of the Grid framework instead. They remain as amorphous constituents in oxidic form in the pores back.

After drying at 100-150 ° C, preferably at 110-120 ° C, and calcination at 450-600 ° C, preferably at 500-550 ° C, the zeolites can be tableted or with a binder in the ratio 90: 10 to 40: 60 wt .-% be superseded. As binders are various Aluminas, preferably boehmite, amorphous aluminosilicates with a SiO₂ / Al₂O₃ ratio of 25: 75 to 95: 5, preferably 75:25, silica, preferably highly dispersed SiO₂ mixtures of highly dispersed SiO and fumed Al₂O₃ and clay. After deformation, the extrudates become or briquettes dried at 110 ° C / 16 h and at 550 ° C / 16 h calcined.

But there is also the possibility of the zeolites for the first time to undergo calcination after deformation.

Are the zeolites without binders as strands or Tablets used, so can peptizer for Stabilization of deformation can be used. For this For example, ethylcellulose, stearic acid, Potato starch, formic acid, oxalic acid, acetic acid, Nitric acid, ammonia, amines, silicates and graphite or their mixtures.

The operating pressure is between 0.01-1 bar, preferably 0.05-0.5 bar, more preferably 0.08-0.25 bar. On narrow temperature range around 300 ° C and especially smaller 300 ° C is particularly favorable at a pressure of 0.08-0.25 bar.  

The loading of the catalyst with cyclohexanone oxime, expressed by the weight hourly space velocity (kg / h of oxime per kg of catalyst), is WHSV = 0.1-10 h ^-1 , preferably 0.2-5 h ^-1 . Water is preferably used in a ratio of <2.5 mol: 1 (oxime). The reaction can be carried out both in a fixed bed and in a fluidized bed.

In a fixed bed process, the starting materials are mixed in the Usually before passing through an evaporator in the reaction zone be directed. As catalysts come here tabletted or extruded moldings are used, the middle Grain sizes between 0.5 and 5 mm can be.

In the fluidized bed process, the individual components mixed or separated via a pre-evaporator or directly be guided into the fluidized bed. This proves itself Fluidized material in extruded form with average diameters of 80-250 microns as particularly favorable.

Sales fall short of a certain trial duration of a fixed value, the activity of the Catalyst recovered by recalcination become. The regeneration temperature is 350-650 ° C, preferably 400-550 ° C, most preferably 450-500 ° C. The regeneration time depends on the rest activity of the catalyst and is between 16 hours and 96 hours. This can be pure oxygen, air or Surprisingly, pure nitrogen used become. If nitrogen is used as a regeneration gas, The treatment time is longer than when using air.

The following examples illustrate this inventive method.

Description of the catalysts

Catalyst A approach [G] SiO2 (Aerosil 200) 64.0 B (OH) 3 12.2 Hexamethylenediamine (50% solution in water) 800.0.

The hexamethylenediamine solution is placed in a PE beaker submitted. To this is added with stirring the boric acid and Stir until it is completely dissolved. These Solution is introduced into a stirred autoclave and the SiO added with stirring within 10 min. you synthesized in a sealed autoclave for 14 days 170 ° C with a stirrer speed of 50 U / min. To Cooling the batch will remove this from the autoclave away. The supernatant solution becomes cautious decanted and the remaining solid on a Filter applied and thoroughly with deionized water rewashed. The product is left at 110 ° C for 12 h dried and then 12 h at 550 ° C under air calcined.

shape

100 g of the catalyst powder is intimately mixed with a shaping aid and 100 g of water. The mixture is extruded at a pressure of 80 bar to strands of 2 mm diameter. The strands are dried for 12 h at 110 ° C and calcined at 550 ° C for 12 h. Crushing on a sieve with the desired mesh size and screening of the fine fraction brings the catalyst grains to the correct grain size.

Catalyst B approach [G] Silica sol (LUDOX) 79.6 borate 3.9 tetrapropylammonium 22.2 deionized water 89.0 Ammonia solution (25% by weight) 72.0.

Silica sol, TPAOH, the deionized water and the Borguelle are presented in a stirred autoclave. This suspension the ammonia solution is added. One synthesizes in sealed autoclave for 7 days at 185 ° C with a Stirrer speed of 100 rpm. After cooling the Approach, this is removed from the autoclave. The supernatant solution is carefully decanted off and the remaining solid is applied to a filter and with thoroughly washed with deionized water. The product is dried for 12 h at 110 ° C and then 12 h calcined at 550 ° C under air.

shape

The shaping takes place as in Catalyst A.

Catalyst C approach [G] SiO₂ (Aerosil) 8.0 B (OH) ₃ 3:39 tetrapropylammoniumbromide 8.61 ammonium fluoride 2:47 deionized water 168.0.

The deionized water in a 200 ml PTFE beaker submitted. The boric acid is dissolved in the water with stirring.  

Subsequently, first ammonium fluoride, then TPABr added. Finally, SiO₂ is stirred. you synthesized in a sealed autoclave for 8 days 186. ° C. After cooling, the supernatant solution carefully decanted off and the remaining solid on applied a filter and with deionized water thoroughly washed. The product is added over 12 h Dried at 110 ° C and then 12 h at 550 ° C under air calcined.

shape

The shaping takes place as in Catalyst A.

Catalyst D

Commercially available HZSM-5 with Si / Al = 54; ZEOCAT PZ- 2 / 54H of Uetikon

Catalyst E

Commercially available catalyst from Degussa; Aerosil 200
Characterization: SiO₂

Catalyst F approach [G] tetraethylorthosilicate 500 ethanol 1070 Tetra-n-propylammonium hydroxide (10% solution in water) 1120th

Tetraethyl orthosilicate, tetra-n-propylammonium hydroxide and Ethanol is in a 5-liter steel autoclave for 120 min intensively mixed. Subsequently, the lid  closed and at 105 ° C with vigorous stirring, the solution crystallized. After 96 hours, the Synthesis stopped, the catalyst washed, at Dried at 110 ° C / 16 h and calcined at 550 ° C / 12 h. It Silicalite was obtained.

shape

The shaping takes place as in Catalyst A.

Catalyst G

5 g of the undeformed catalyst F were mixed with a Mixture of 5 g aqueous ammonium nitrate solution (7.5% strength) and 10 g of aqueous ammonia (28%) in an hour Stir 100 ml of one-necked flask at room temperature. The Catalyst was filtered off and the same procedure subjected to another three times. Subsequently, the powder became washed and dried. It was compressed into tablets and crushed into grains of grain size 1-1.6 mm.

Catalyst H

Preparation such as Catalyst G. The treatment, however, becomes in an autoclave at 90 ° C under autogenous pressure carried out.

Catalyst I

5 g of the powdery catalyst B are in a Ceramic tube of 4 cm diameter at 400 ° C of a Nitrogen-steam mixture overflowed for 2 hours. The Mass fraction of the water is 50%. After Steam treatment, the catalyst is in a 100 ml One-necked flask in an aqueous HCl solution (pH 6) at Room temperature stirred for 24 h. Subsequently, the  Drying. The dried powder becomes tablets compressed and comminuted into grains of grain size 1-1.6 mm.

Catalyst J

Production and shaping of this catalyst takes place as in Catalyst I. The steam treatment, however performed at 550 ° C pressure.

After the steam treatment, the catalyst is in a 100 ml one-necked flask in an aqueous HCl solution (pH 6) stirred at room temperature for 24 h. Then done Drying and shaping as in Catalyst I.

Description of the pilot plant with fixed bed reactor

The catalytic investigations in a fixed bed were carried out in a tubular reactor with an inner diameter of 6 mm carried out. The reaction zone was in an oven one uniform temperature over the entire reaction path pretending. At the end of the reaction zone prevented a stitch wire discharging the catalyst grains. cyclohexanone was mixed with the solvents and any addition components in a storage container and mixed over one Mini dosing pump fed into the pre-evaporator. Here was the mixture mixed with the carrier gas and gaseous in led the reactor. The reaction products were in a Cold trap cooled with liquid nitrogen, collected, thawed and a gas chromatographic Subjected to analysis. The mass balances were over 99%.  

Table 1

Influence of temperature and pressure reduction

Example 8

Diagram 1: Influence of the pressure reduction at 300 ° C and 350 ° C:

Example 9

Diagram 2: Influence of the temperature at 0.1 and 1 bar:

Examples 10-12

Table 2

Influence of the residence time and the pressure on the reaction

Examples 13-17

Influence of various solvents on the reaction at 300 ° C and underpressure

Example 18

Diagram 3: Course of conversion and selectivity over 20 hours

Examples 19-24

Table 4

Influence of addition of water and negative pressure in the presence of ethanol

Table 5

Influence of addition of water and negative pressure in the presence of methanol

Example 25

Diagram 4: Influence of water on the service life of the catalyst

Examples 26-28

Table 6

Influence of crystallite size

Example 29

The example shows the regeneration with oxygen

Table 7

Turnover and selectivity after several regeneration cycles

Example 30

The example shows the regeneration with nitrogen

Table 8

Turnover and selectivity after several regeneration cycles

Examples 31 * and 32 *

Table 9

Turnover and selectivity of highly silical catalysts

Examples 33 and 34

Catalyst F was treated as follows:
The catalyst granules were stirred in a solution of aqueous ammonia and ammonium nitrate three times for one hour, washed and dried at 110 ° C. This treatment was carried out on the one hand in a one-necked flask at room temperature (Example 33) and on the other in an autoclave at 90 ° C under autogenous pressure (Example 34). The experimental results obtained with the treated catalysts are shown in Table 10.

Table 10

Conversion and selectivity of the modified highly silicitic MFI zeolite (silicalite)

Frequencies of the individual silanol groups in FT-IR:
terminal ⇒ n = 3745 ± 5 cm ^-1
geminal ⇒ n = 3725 cm ^-1
vicinal bridges ⇒ n = 3725 u. 3500 cm ^-1
Silanolnest ⇒ n = 3500 cm ^-1

Examples 35-37

These examples show the influence of water vapor and Acid treatment on the catalytic activity and Selectivity.

Table 11

Catalyst treatment with water vapor (2 h) and aqueous HCl solution (pH 4, 24 h)

Description of the pilot plant with fluidized bed reactor:
In the fluidized bed process, a vortex reactor with an inner diameter of 51 mm and a vortex zone of 600 mm was used. The catalysts were on a glass frit with pore sizes less than 30 microns. Cyclohexanone oxime was mixed with the solvents and any additional components in a receiver and passed through a Minidosierpumpe in the pre-evaporator. Here, the mixture was mixed with the carrier gas and passed in gaseous form into the reactor. The mixture could also be injected directly into the vortex zone. The reaction products were passed through a water cooler and then the uncondensed portions were collected in a liquid nitrogen cooled cold trap. For analysis purposes, a partial gas stream was discharged directly from the settling zone of the vortex reactor and analyzed by gas chromatography.

Examples 38 and 39

Diagram 5

Influence of the educt feed on the selectivity for ε-caprolactam

The conversion in both examples is 100% by weight.  

Examples 40-42

Diagram 6

Influence of the temperature on the conversion of cyclohexanone oxime

Diagram 7

Influence of the temperature on the selectivity for ε-caprolactam

Examples 43-45

Table 12

Conversion and selectivity upon addition of water to the starting material

Claims (15)

1. A process for the preparation of ε-caprolactam by Beckmann rearrangement of cyclohexanone oxime in the gas phase in the temperature range of 250-450 ° C to zeolite catalysts, characterized in that one uses MFI zeolites, which at the surface due to the absence of central metal atoms OH groups which are arranged symmetrically to each other. 2. Method according to claim 1, characterized, the central metal atoms from the group Si, Al, B, Fe, Ga, Cr, Be, As, Sb, Ge, Ti, Zr or Hf come. 3. Method according to claim 1, characterized, that one built only from silicon tetrahedra orthorhombic zeolite with MFI structure. 4. The method according to claim 1, characterized, that is a substituted with B atoms MFI zeolite used as precursor. 5. The method according to claim 4, characterized, the ratio Si: B is between 5 and 40: 1. 6. The method according to claim 4 and 5, characterized, that the boron-MFI zeolites with the help of diamines and Triamines were synthesized alkali-free.   7. The method according to one or more of the claims 1 to 6, characterized, that the primary particle size of the MFI zeolite crystals smaller than 5 μm. 8. The method according to one or more of the claims 1 to 7, characterized, that per mole of cyclohexanone oxime more than 2.5 moles of water be used. 9. The method according to one or more of the claims 1 to 8, characterized, that the reaction at a pressure in the range of 0.01-1 bar and a temperature of 280-310 ° C performed becomes. 10. The method according to one or more of the claims 1 to 9, characterized, that when using a fluidized bed process the Starting materials are fed directly into the vortex zone. 11. Process for the preparation of zeolitic Catalysts for use in processes according to the Claims 1 to 3, characterized, that highly silicious MFI zeolites (silicalite) with monoclinic structure at 20 to 150 ° C under autogenous Pressure in an autoclave with a solution of Ammonia salts and / or aqueous ammonia solution in Contact, the orthorhombic product after that Reaction separates and dries. 12. Process for the preparation of zeolitic Catalysts for use in processes according to the  Claims 1, 4 and 5, characterized, that boron-containing MFI zeolites at a temperature from 300-650 ° C treated with steam and optionally an acid treatment at a pH from 4-6 connects. 13. Process for the preparation of zeolitic Catalysts for use in processes according to the Claims 1, 4 and 5, characterized, that boron-containing MFI zeolites at a temperature from 60-80 ° C with a 3-25 wt .-% aqueous Acid treated, then washed and at 400-500 ° C. dries. 14. Process according to claims 1 to 5, characterized, that B-containing zeolites of MFI-type at temperatures calcined between 500 and 700 ° C under oxygen become. 15. Process for the regeneration of zeolitic Catalysts according to claims 11 to 14, characterized, that the regeneration of the catalysts with pure Nitrogen in the temperature range of 400-650 ° C performs.