TW201429547A - Methanol treatment of aluminosilicate-containing ATAE cleavage catalysts - Google Patents

Abstract

The invention relates to a process for producing an aluminosilicate-containing catalyst which is intended for use in the cleavage of alkyl tert-alkyl ethers (ATAE) to form olefins and alcohols. It has the object of providing a process for producing an acidic heterogeneous catalyst which displays a reduced initial activity in the ATAE cleavage. The object is achieved by the catalyst being treated with methanol before being used in the ATAE cleavage.

Description

Methanol treatment method for aluminum citrate catalyst for alkyl tertiary alkyl ether (ATAE) cracking

This invention relates to a process for the preparation of a catalyst comprising aluminum ruthenate which is intended for the cracking of alkyl tertiary alkyl ethers to form olefins and alcohols. The invention further relates to a process for the cracking of alkyl tertiary alkyl ethers to olefins and alcohols in the presence of such a catalyst.

Alkyl tertiary alkyl ether (ATAE) is a compound of formula II

Wherein the R group is an alkyl group having 1 or 2 carbon atoms, the R ¹ group is H or a methyl or ethyl group, and the R ² and R ³ groups are each a methyl or ethyl group, wherein R ^{The 2} and R ³ groups may be the same or different.

Important representatives of the ATAE class are methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE) and tertiary amyl methyl ether (TAME).

Olefins (also known as alkenes) are unsaturated hydrocarbons of formula I

Wherein the R group is an alkyl group having 1 or 2 carbon atoms, the R ¹ group is H or a methyl or ethyl group, and the R ² and R ³ groups are each a methyl or ethyl group, wherein R ^{The 2} and R ³ groups may be the same or different.

Isobutylene is an olefin within the meaning of the meaning herein.

For the purposes of the present invention, an alcohol is a compound of formula III R-OH III

Wherein the R group is an alkyl group having 1 or 2 carbon atoms.

Examples of alcohols are methanol and ethanol.

Pure olefins can be synthesized by selective catalytic cracking of the ethers based on them. Thus, for example, isobutylene can be prepared by cleavage of methyl or ethyl tertiary butyl ether (MTBE or ETBE). The corresponding alcohol (methanol or ethanol) is obtained as a by-product of the reaction. The cracking industry can be carried out in the gas phase, in the liquid phase or in a gas/liquid mixed phase. Since the equilibrium of the endothermic reaction shifts to favor the product when the reaction temperature is increased, the reaction in the gas phase is often preferred.

The cleavage reaction can be carried out on an acidic or basic catalyst. In the gas phase process, it is usually used in Br Nsted acid amorphous aluminum citrate or zeolite-based catalyst.

In addition to the main reaction, a series of undesirable secondary and/or subsequent reactions occur, particularly at relatively high reaction temperatures. The most commonly described in the literature for this type of reaction is the formation of methanol, dimethyl ether (diethyl ether or ethanol formed from a) from the target and olefins (e.g., isobutylene to C ₈ - or more olefinic) polymerization of the oligonucleotide .

Since by-products are sometimes difficult to separate from the target product of the reaction, the selective reduction of the product often means a significant increase in the cost for purification.

The development of a catalyst in which the cleavage reaction of ether is carried out at a high rate but whose target product is still highly selective is therefore extremely important.

A number of different cracking catalysts, mainly amorphous or crystalline aluminum silicates doped with or without foreign metals, have been described. These catalysts show significantly different activities for the cleavage reaction and also different selectivity to the target product.

No. 5,227,564 describes a ZSM-5 zeolite catalyst which achieves a 97% MTBE conversion at 190 ° C and 1 bar with an isobutylene selectivity of 99.5% and a methanol selectivity of 96.5%.

On the other hand, EP 1 876 621 A1 describes an amorphous aluminum silicate which is doped with an alkali metal oxide and/or an alkaline earth metal oxide as a catalyst. This catalyst was used to achieve a high isobutylene selectivity of >99.9% and a high methanol selectivity of >97.0% compared to 85% when the reactor was operated at 250 ° C and a gauge pressure of 7 bar. However, this doping results in a significant reduction in the activity of the catalytic material.

A more active catalyst is also described, for example, in the patent application DE 10 2011 005 608 A1, which is hereby incorporated by reference. These can be operated at lower temperatures of 220 ° C with the same conversion of 85%. However, it has been reported that the catalyst must be diluted with twice its catalytically inactive material because of its high activity.

This dilution leads to a permanent reduction in activity and therefore needs to be higher than when The reaction temperature when using undiluted catalyst material.

Dilution also means an increased reactor volume at a given space time yield, which results in higher capital costs and thus adversely affects the economics of the process.

Another possible way to compensate for the decrease in activity is to increase the residence time. However, it can be seen from the data in DE 10 2011 005 608 A1 that the catalyst is also aged like the catalyst described in EP 1 846 621 A1, which leads to a further decrease in activity during the operation, after which the reaction temperature must be increased up to 248 ° C after 1600 hours of operation. Keep conversion rates.

In summary, the prior art knows four different ways to reduce catalyst activity:

. The acid catalyst material is doped with an oxide such as an alkali metal and an alkaline earth metal, which is described, for example, in EP 1946621 A1. This doping leads to neutralization of the active site and thus to a permanent reduction in activity. The aging of the catalyst is not affected by this.

. The catalytically active material is diluted with an inert solid as described, for example, in DE 10 2011 005 608 A1. As a possibility, the dilution can be carried out by mixing the catalytic material and the inert material before the formation of the catalyst, which are then only shaped (for example, ingot or extruded) to produce a shaped body having a reduced content of catalytically active sites. Secondly, the finished forming catalyst can also be introduced into the reactor together with the shaped body of the inert material. Regardless of the type of dilution, significant aging of the catalyst was observed and the final activity after aging was permanently lower than that of the undiluted material.

. WO2011161045A1 describes diluting a feed stream with an inert ingredient. This results in a decrease in reaction rate and an increase in selectivity, but has no effect on the catalyst. A disadvantage of this method is the necessity to separate the inert components from the product stream, which is usually associated with additional often energy consuming separation methods such as rectification or condensation.

. WO 2011161045 A1 additionally describes the continuous introduction of various catalytic toxins into the feed stream in a reactor in order to dissociate the alcohols to form olefins. During the operation, these toxins poison a portion of the active site. Ammonia or all types of organic nitrogen compounds are suggested as suitable materials. In addition, aldehydes, ketones and carboxylic acid esters are said to be suitable. Disadvantages of this method are the necessity of continuously introducing toxic components and the need to separate these compounds from the product stream. Furthermore, it cannot be excluded that the ingredients mentioned react with the starting materials or products of the actual dissociation reaction. Nor does it show that the method can be applied to the cleavage of ethers.

In view of the prior art, it is an object of the present invention to provide a process for preparing an acidic heterogeneous catalyst which exhibits a reduction in initial activity in the cleavage of ATAE. At the same time, the final activity should not be adversely affected in the operation of the catalyst produced. Finally, no inert ingredients or catalytic toxins should be introduced continuously. Another aspect of the invention is to reduce by-product formation by dimerization of the product olefins in the ATAE cracking, as well as to reduce the reduction in activity caused by catalyst aging.

It has now surprisingly been found that the initial activity of the industrial catalyst can be reduced by treatment with methanol as long as this is carried out before the ether cracking. This means that methanol does not have to be introduced continuously into the cracking, but only beforehand. In addition, it has been observed that the methanol treated catalyst forms a minor amount of undesirable by-products. This object is therefore achieved by treating the catalyst with methanol before the catalyst is used in the ATAE cracking.

The present invention therefore provides a process for the preparation of an aluminum phthalate-containing catalyst intended for use in the cracking of alkyl tertiary alkyl ethers to form olefins and alcohols, wherein the catalyst is treated with methanol prior to use.

The present invention can be used in an amorphous or crystalline aluminum-containing catalyst, that is, a catalyst mainly composed of alumina (Al ₂ O ₃ ) and cerium oxide (SiO ₂ ). In particular, the present invention can also be applied to a catalyst comprising an amorphous or crystalline aluminum silicate, i.e., a compound of aluminum oxide and cerium oxide, wherein aluminum also occupies a lattice position. Therefore, it is also expressly included that a compound mainly composed of cerium oxide and containing 1% or less of alumina. This type of catalyst is a group of acidic heterogeneous catalysts.

Even though the catalyst used in accordance with the invention consists almost entirely of alumina and ceria, trace amounts of alkali metal oxides and/or alkaline earth metal oxides may additionally be present. These are naturally present in the material, such as K ₂ O, or deliberately introduced into the catalyst, such as MgO.

The composition of the catalyst that has been treated in accordance with the present invention can be defined as follows:矽: from 50 to 99.9% by mass (calculated as SiO ₂ ); Aluminum: from 0.1 to 50% by mass, preferably from 0.1 to 20% by mass, particularly preferably from 0.5 to 11% by mass (calculated as Al ₂ O ₃ ); Alkali metal: from 0 to 15% by mass (calculated as M ₂ O, where M is an alkali metal); Alkaline earth metal: from 0 to 30% by mass (calculated as MO, where M is an alkaline earth metal).

It can be seen from this definition that the content of alkaline earth metal oxides and alkali metal oxides is not mandatory. Of course, the ratio of the components present is 100% by mass in total.

The present invention focuses on the treatment of such catalysts with methanol. The preparation of the aluminum citrate catalyst prior to the methanol treatment is the subject of patent application DE 10 2011 005 608 A1, which is not yet disclosed on the filing date. The significant implementation steps for the preparation of the catalyst according to the invention are therefore: a) flame hydrolysis preparation of mixed oxides containing cerium and aluminum; b) conversion of mixed oxides into catalyst intermediates; c) treatment with methanol Medium intermediate to produce a catalyst.

Flame hydrolysis preparation of mixed oxides containing cerium and aluminum

Flame-hydrolyzed preparations of mixed oxides of cerium and aluminum have been described in the prior art, in particular in DE 198 761 716 A1, DE 196 650 550 A1, EP-A 0 850 876 and Koth et al. Chem.-Ing.-Tech. 1980, 52, 628 ff. And below.

Here, in the so-called "co-fumed process", volatile bismuth and aluminum compounds (which are often ruthenium tetrachloride and aluminum trichloride) are sprayed into a composition consisting of hydrogen and oxygen or air. In the H ₂ /O ₂ flame. The volatile cerium and aluminum compound are hydrolyzed by water formed in the H ₂ /O ₂ flame to form a mixed type oxide and an acid of a counter ion of the cerium and the aluminum compound.

In an alternative doping method, the aerosol is fed into a H ₂ /O ₂ flame, wherein the oxide (eg, cerium oxide) is formed by a volatile compound (eg, hafnium tetrachloride) present in the aerosol. The flame is hydrolyzed by introducing a salt of an element (for example, aluminum) as a dopant and thus forms a corresponding mixed type oxide.

In the two processes, the coproducts formed are subsequently subjected to various steps, in particular, as in DE 198 16 761 A1, DE 19 650 500 A1, EP-A 0 850 876 and Koth et al. Chem.-Ing.-Tech. 1980, 52, 628 ff and below. The removal.

The oxide or mixed oxide obtained by flame hydrolysis has the following characteristics: High chemical purity, Clearly defined spherical original particles, There is almost no internal surface area.

In the preparation method of the present invention, it is preferred to use a cerium-aluminum mixed type oxide powder mainly or completely in the form of aggregated primary particles and therein. The weight ratio of (Al ₂ O ₃ /SiO ₂ ) _ttl in the total primary particles is from 0.002 to 0.05, preferably from 0.003 to 0.015, and particularly preferably from 0.005 to 0.01. By weight of the surface layer having a thickness of about 5nm primary particle ratio _{(Al 2 O 3 / SiO 2} ) less than the total _{surface of} the original system and those particles. BET surface area from 50 lines to 250m ² / g, preferably from 100 to 200m ² / g.

The bismuth-aluminum mixed type oxide powder is characterized in particular by the fact that the proportion of alumina is very small compared to cerium oxide and the weight ratio of the original particles in the surface layer (Al ₂ O ₃ /SiO ₂ ) _surface It is less than the weight ratio in the total original particles. This indicates that the alumina concentration at the surface is further reduced. The total primary particles include the proportion of cerium oxide and aluminum oxide in the surface layer. Preferably, it may be a bismuth-aluminum mixed type oxide powder according to the present invention, wherein the _surface of (Al ₂ O ₃ /SiO ₂ ) _ttl /(Al ₂ O ₃ /SiO ₂ ) _is from 1.3 to 20, preferably from 1.4 to 10 and particularly preferred from 1.6 to 5, where "ttl." denotes the total primary particles.

The cerium-aluminum mixed type oxide powder prepared in the step a) preferably has a weight ratio of (Al ₂ O ₃ /SiO ₂ ) _ttl of from 0.005 to 0.015, and a ratio of from 1.3 to 20 (Al ₂ O ₃ /SiO ₂ ) _ttl / (Al ₂ O ₃ /SiO ₂ ) _surface and BET surface area from 100 to 200 m ² /g.

For the purpose of the present invention, the mixed oxide powder is an atomic-level intimate mixture of the mixed oxide component alumina and ceria, and the primary particles also have Si-O-Al bonds. The surfaces of these primary particles are substantially completely non-porous.

The bismuth-aluminum mixed type oxide powder is preferably obtained by flame hydrolysis and/or flame oxidation in a flame produced by the reaction of hydrazine and an aluminum compound by hydrogen and oxygen. These powders are described as "pyrolysis" or "smoke". The reaction first forms finely divided primary particles which grow together during further reaction to form aggregates which can be further combined to form agglomerates.

The weight ratio on the surface can be determined, for example, by X-ray induced photoelectron spectroscopy (XPS analysis) of the powder. In addition, the composition of the surface composition The signal can be measured by energy dispersive X-ray irradiation (TEM-EDX analysis) of individual primary particles.

The weight ratio in the total primary particles is determined by chemical or physicochemical methods such as X-ray fluorescence analysis of the powder.

Further, it has been found that when the bismuth-aluminum mixed type oxide powder has a dibutyl citrate value of 300 to 350 (expressed as g/100 g of a mixed type oxide of dibutyl phthalate (DBP)), advantageous. The DBP value is a measure of the aggregate structure. A low value corresponds to a low structure and a high value corresponds to a high structure. A preferred range of 300 to 350 corresponds to a high structure. In DBP absorption, the force absorption or moment (Nm) of the DBP meter rotating blade when adding the defined amount of DBP (comparable to titration) is measured. Here, the powder according to the invention shows a sharply defined maximum and then drops when a particular DBP is added. Dibutyl phthalate absorption can be measured, for example, using a RHEOCORD 90 instrument from Haake, Karisruhe. For this purpose, 12 g of bismuth-aluminum mixed oxide powder (to an accuracy of 0.001 g) was weighed into a kneading chamber which was sealed with a lid and passed through a hole in the lid at a predetermined metering rate of 0.0667 ml/sec. Dibutyl phthalate was metered. The kneader was operated at a rotor speed of 125 rpm. After the maximum torque is reached, the metering of the kneader and DBP is automatically turned off. DBP absorption was calculated from the amount of DBP consumed and the amount of particles weighed as follows: DBP value (g/100 g) = (DBP consumption (g) / powder weight (g)) x 100.

The flame hydrolysis preparation of the cerium-aluminum mixed type oxide is preferably carried out by the following method, wherein a1) using a carrier gas will contain one or more selected from the group consisting of CH ₃ SiCl ₃ , (CH ₃ ) ₂ SiCl ₂ , (CH ₃ ) ₃ SiCl The vapor of the ruthenium compound of the group consisting of (nC ₃ H ₇ )SiCl ₃ and the vapor of the hydrolyzable and oxidizable aluminum compound are separately or together are fed into the mixing chamber, and the aluminum compound (calculated as Al ₂ O ₃ ) is a ruthenium compound. The weight ratio (calculated as SiO ₂ ) is from 0.003 to 0.05, a2) from which at least one fuel gas and air are introduced into the mixing chamber, wherein the total amount of oxygen in the air is at least sufficient for the combustion gas And complete combustion of the bismuth compound and the aluminum compound, a3) the vapor of the bismuth compound and the mixture of the aluminum compound, the combustion gas and the vapor of the air are ignited in the burner and the flame is burned into the reaction chamber, a4) subsequently from the gas The material separated off the solid and the solid was then treated with water vapor.

The process can also be carried out using a vapor of a ruthenium compound capable of containing up to 40% by weight of SiCl ₄ . A mixture of from 65 to 80% by weight of CH ₃ SiCl ₃ and from 20 to 35% by weight of SiCl ₄ may be particularly preferred. As the aluminum compound, aluminum chloride is preferred. Preferably, the fuel gas is selected from the group consisting of hydrogen, methane, ethane, propane, and mixtures thereof. Particularly good for hydrogen. The air introduced into the mixing chamber is at least sufficient for complete combustion of the fuel gas and complete combustion of the bismuth compound and the aluminum compound. Usually, excess air is used. The treatment with steam is used to remove a large amount of chlorine residue adhering to the particles such that the powder contains no more than 1% by weight of chloride, preferably no more than 0.2% by weight of chloride.

Further, the oxide or mixed type oxide produced by flame hydrolysis is X-ray-amorphous. The material is X-ray-amorphous when its long-range order is within the coherence length of the x-radiation used and therefore does not interfere with any pattern.

Conversion of mixed oxides into catalyst intermediates

For the purposes of the present invention, a catalyst intermediate is a material that catalyzes the cleavage of ATAE but has not been subjected to methanol treatment to reduce its initial activity.

Mixed oxides containing aluminum and cerium prepared by flame hydrolysis will generally be catalytically active so that they can be used in principle without further treatment as a catalyst intermediate. This is especially because the mixed oxide prepared according to the invention already has the relevant material composition of the catalyst:矽: from 50 to 99.9% by mass (calculated as SiO ₂ ); Aluminum: from 0.1 to 50% by mass, preferably from 0.1 to 20% by mass, particularly preferably from 0.5 to 11% by mass (calculated as Al ₂ O ₃ ); Alkali metal: from 0 to 15% by mass (calculated as M ₂ O, where M is an alkali metal); Alkaline earth metal: from 0 to 30% by mass (calculated as MO, where M is an alkaline earth metal).

However, it is useful to subject the mixed oxide to an additional embodiment to convert it to a photocatalyst intermediate. These steps include, inter alia, shaping and/or treatment with an aqueous solution of an acidic alkali metal and/or alkaline earth metal hydroxide or mixing of a mixed oxide with an alkali metal salt and/or an alkaline earth metal salt.

Treatment with an aqueous solution of an acidic alkali metal and/or alkaline earth metal hydroxide The mixing of the mixed oxide with the alkali metal salt and/or the alkaline earth metal salt has the purpose of introducing an alkali metal and/or an alkaline earth metal into the catalyst. Doping of these ingredients reduces activity but has no effect on aging characteristics. Therefore, the doping can be omitted, so the content of the alkali metal and/or alkaline earth metal can also be zero. Therefore, the introduction of alkali metal and/or alkaline earth metal into the catalyst intermediate will not be further described. Details of such a process can be found in the patent application DE 10 2011 005 608 A1, in particular examples 3 and 4.

More importantly, the forming takes place during the conversion of the mixed oxide into a catalyst intermediate.

Even though powdered catalysts can be used for cracking at ATBE, for industrial use, the catalyst should undergo macroscopic shaping so that it can be handled more easily to minimize flow slowing in the reactor and optimize heat transfer. The microcatalyst powder can be shaped in a manner known per se (for example EP 1 956 621 A1) to produce macroscopic tablets, granules or extrudates. If necessary, add a binder or temporary aid to form. As suitable binders, it is possible to use aluminas, ceramic clays, colloids, for example, and amorphous zeolites. As a temporary auxiliary, it is possible to use, for example, water, an aqueous solution, a water substitute such as a glycol, a polyol, and a fixing agent such as a cellulose ether, a plasticizer such as a polysaccharide, and a pressurizing aid. (such as nonionic wax dispersion).

The forming is preferably followed by calcination, during which the residual organic matter of the catalytic material is burned. In this way, the catalyst intermediate is preferably free of organic components.

The conversion of the mixed oxide into a catalyst intermediate preferably comprises the following sequential steps: b1) shaping the powdered mixed oxide giant form and temporarily using it And/or binder; b2) calcining the shaped mixed oxide to produce a catalyst intermediate.

Methanol treatment

According to the invention, the catalyst intermediate is subjected to methanol treatment in order to reduce its initial activity. Only a catalyst which can be used for the purpose of the present invention is obtained in this way.

Since methanol is re-discharged by calcination, the methanol treatment must be carried out after any calcination.

Methanol treatment can be carried out away from where the catalyst is used (offsite) or where the catalyst is used (in situ).

The off-site treatment is carried out at the catalyst factory. The finished catalyst, which has been treated with methanol, is transported from there to the reactor of the ATAE cracker where the finished catalyst is used, where it is installed and ready for use.

In the case of in-situ treatment, only catalyst intermediates that are not treated with methanol are produced in the catalyst plant. The catalyst intermediate is then transported to the reactor of the ATAE cracker where the catalyst intermediate is used and installed there. Methanol treatment was then carried out in a reactor of the ATAE cracking plant before the cracking operation started therein.

The in situ treatment of the catalyst is not known in principle: therefore, WO 2011/000695 A1 describes the regeneration of the aluminum phthalate-containing ATAE cracking catalyst where it is used. Regeneration is carried out by rinsing with water to activate the catalyst. Regeneration is required in some cases in order to restore the activity of the catalyst that is deactivated due to long-term use. So this is the methanol treatment implemented here. A measure of the opposite effect of the effect (which is used to reduce the initial activity).

The methanol treatment according to the invention is carried out by immersing the liquid and/or gaseous methanol through a catalyst or catalyst intermediate or by immersing the catalyst intermediate in a liquid and/or gaseous methanol. The temperature and pressure conditions are selected based on the desired state of the material of the methanol. It may be noted that this treatment can also be carried out using a two-phase mixture of liquid and gaseous methanol.

When methanol passes through the catalyst intermediate, the space velocity (WHSV, kg of methanol/kg/cell of catalyst) should be in the range of from 0.1 to 20 h ^-1 , preferably from 0.5 to 5 h ^-1 .

The pressure during the treatment with methanol should be in the range from 0.1 to 1.5 MPa (absolute), especially from 0.5 to 0.8 MPa (absolute). A pressure of 0.1 MPa (absolute) corresponds to normal atmospheric pressure. This will be advantageous, especially in the off-site processing of catalysts.

The temperature at which the treatment with methanol is carried out should be in the range from 50 to 300 ° C; preferably in the range from 100 to 200 ° C and the temperature should preferably be in the range from 115 to 190 ° C.

In the treatment of catalysts, it has been found to be particularly advantageous to select temperature and pressure conditions which are also substantially advantageous during subsequent ether cracking. This is particularly easy in the in-situ treatment, as this is done in a cracking plant where the reaction conditions can be applied in any case.

The acidic heterogeneous catalyst converts methanol to dimethyl ether. In order to maintain low methanol loss during the treatment of the catalyst with methanol according to the present invention, the methanol treatment should be carried out in such a manner that methanol is converted to dimethyl ether system by less than 10%, preferably less than 1% and particularly preferably less than 0.2%. The reaction conditions for the turn Turning into the key. In particular, this goal can be achieved under conditions corresponding to the conditions of ATAE cleavage.

Catalysts prepared in accordance with the present invention are used to cleave ATAE to form olefins and alcohols.

The invention therefore also relates to a process for the cleavage of an alkyl tertiary alkyl ether of formula II (ATAE) to an olefin of formula I and an alcohol of formula III,

R-OH III

Wherein, in the formulae I to III, the R group is an alkyl group having 1 or 2 carbon atoms, the R ¹ group is H or a methyl or ethyl group, and the R ² and R ³ groups are each a methyl group. Or an ethyl group wherein the R ² and R ³ groups may be the same or different, wherein the cleavage is carried out in the presence of an aluminum phthalate catalyst which has been treated with methanol.

The catalyst used in the cracking method has the following composition in a total of up to 100%:矽: from 50 to 99.9% by mass (calculated as SiO ₂ ); Aluminum: from 0.1 to 50% by mass, preferably from 0.1 to 20% by mass, particularly preferably from 0.5 to 11% by mass (calculated as Al ₂ O ₃ ); Alkali metal: from 0 to 15% by mass (calculated as M ₂ O, where M is an alkali metal); Alkaline earth metal: from 0 to 30% by mass (calculated as MO, where M is an alkaline earth metal).

If a catalyst that has been treated off-site is used, the process of the invention comprises the following sequential steps: a) introducing a catalyst that has been treated with methanol into the reactor; b) performing the cracking in the reactor.

If the catalyst is to be treated in situ with methanol, the process of the invention comprises the following sequential steps: a) introducing a catalyst or catalyst intermediate not treated with methanol into the reactor; b) treating the reactor with methanol without Treated catalyst or catalyst intermediate; c) the cleavage is carried out in a reactor.

The treatment with methanol is preferably carried out under conditions of pressure and temperature substantially corresponding to the cracking reaction, or introduction of a catalyst which has been treated under these conditions. This has the advantage that after processing, it is only necessary to change the feed to the reactor to ATAE without loss of time due to additional heating or cooling periods. Furthermore, it has been observed that under the conditions of cracking, methanol treatment shows a particularly remarkable effect and during this treatment, the conversion of methanol to dimethyl ether is in the desired low range.

In principle it is conceivable to treat the catalyst with another alcohol instead of methanol and as a result the same effect can be achieved. A variant of the invention thus includes another The alcohol completely or partially replaces the methanol which treats the catalyst. Possible alternative alcohols are in particular monohydric alcohols and in particular ethanol. For the purposes of the present invention, the complete replacement of methanol with ethanol indicates that the catalyst is treated with ethanol instead of methanol. Partial replacement with ethanol indicates that the catalyst is treated with a mixture of methanol and ethanol.

Basically, any of the ATAEs can be cleaved to the corresponding olefins and alcohols using the process of the present invention. In the cleavage method according to the invention, it is preferred to cleave the compound of formula II wherein R is a methyl or ethyl group. The alkyl tertiary alkyl ether which can be used in the cracking process of the present invention is, for example, methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE) or tertiary amyl methyl ether. (TAME). In the use according to the invention of a catalyst which has been pretreated according to the invention, it is particularly preferred that the methyl tertiary butyl ether is cleaved to isobutylene and methanol or ethyl tertiary butyl ether to be cleaved to isobutene and ethanol. Very particularly good is the cracking of MTBE into isobutylene and methanol in the gas phase.

An ATAE which can be derived from various methods is used in the lysis method of the present invention. The preparation of ATAE is known in the prior art and is carried out on a large industrial scale. A method of preparing MTBE is described, for example, in DE 10 102 082 A1. Processes for the preparation of ETBE are disclosed, for example, in DE 10 2005 062 700 A1, DE 10 2005 062 722 A1, DE 10 2005 062 699 A1 or DE 10 2006 003 492 A1.

ATAE cracking, source of starting materials and use of products

The cracking according to the invention using the treated catalyst according to the invention is preferably carried out in the gas phase at a temperature of from 110 to 400 °C. If MTBE is used as the starting material, the MTBE is cleaved into isobutylene and methanol. 150 to 350 ° C, particularly preferably from 180 to 300 ° C.

The cleavage is preferably carried out at a reaction pressure of from 1 to 20 bar (absolute). When isobutene is the product, it may be advantageous to carry out the cracking process of the present invention at a pressure of from 2 to 10 bar abs, preferably from 5 to 8 bar abs. This is particularly advantageous because isobutylene can be condensed with cooling water under these pressures.

The specific space velocity (WHSV; grams of starting material per gram of catalyst per gram per hour at room temperature) in the cracking process of the present invention is preferably from 0.1 to 100 h ^-1 , more preferably from 0.5 to 30h ^-1 . If MTBE is used as the starting material, the cleavage of MTBE to isobutylene and methanol is preferably carried out from 0.1 to 100 h ^-1 , particularly preferably from 0.25 to 25 h ^-1 of WHSV.

In order to keep the overhead of the work-up of the cleavage product mixture low, it is preferred to seek high single pass conversion. The process of the present invention is preferably carried out such that the conversion of the compound to be cleaved is higher than 70%, preferably higher than 80%, and more preferably higher than 90% to 100%. Limiting the conversion can be advantageous when the starting material contains secondary components that interfere. If, for example, the starting material mixture contains 2-methoxybutane in addition to the MTBE to be cracked, it may be desirable to reduce the single pass conversion so as not to exceed the ratio of linear butenes to isobutylene in the specified reaction mixture. . It may therefore be advantageous to limit the allowable conversion of MTBE to the higher ratio of 2-methoxybutane in the starting material mixture comprising MTBE. Limitations of conversion can be achieved, for example, by increasing WHSV and/or lowering the reaction temperature.

The activity and/or selectivity of some of the catalyst may be advantageous for the proportion of water to be added to the reactor feed. So, for example, JP 19912201 Description: Water is continuously added to an aluminum silicate salt doped with an alkali metal or alkaline earth metal to reduce the formation of secondary components.

Water is optionally added to adjust the catalyst so that the proportion of water in the inlet of the reactor is preferably from 0 to 5% by mass, particularly preferably from 0.2 to 1.5% by mass. As the water to be introduced, it is preferred to completely demineralize or distill water or water vapor.

The cleavage product mixture can be purified by known industrial methods. The unreacted starting material can optionally be recycled to the crack after partial discharge or purification.

The resulting isoolefins can be used in a variety of ways. Isobutene prepared by the cracking process of the present invention can be used, in particular for the preparation of butyl rubber, polyisobutylene, isobutylene oligomers, branched C ₅ -aldehydes, C ₅ -carboxylic acids, C ₅ -alcohols, C ₅ -Olefin, tertiary-butyl aromatics, and methacrylic acid and esters thereof.

The alcohol obtained in the cleavage of ATAE can be reused after isolation purification, for example for the synthesis of ATAE.

If the ATAE is a methyl tertiary alkyl ether (MTBE), the resulting methanol can also be used in the methanol treatment according to the invention for the catalyst. The methanol used for methanol treatment may also be used optionally for the synthesis of ATAE after purification.

Instance

The following examples illustrate the process of the present invention for methanol treatment of acidic heterogeneous catalysts and the use of ether cracking of catalysts which have been pretreated according to the invention. law.

Example 0.1: Preparation of cerium-aluminum mixed oxide powder

A vapor of a mixture of 45 kg/h of CH ₃ SiCl ₃ and 15 kg/h of SiCl ₄ and 0.6 kg/h of aluminum chloride vapor were introduced into the mixing chamber separately from each other by using nitrogen as a carrier gas. In the mixing chamber of the burner, the vapor is mixed with 14.6 standard m ³ /h of hydrogen and 129 standard m ³ /h of dry air and fed via a central tube, which is ignited at the end of the central tube and is here Burning. The formed powder was then collected on a filter and treated with steam at 400 to 700 °C. The powder contained 99% by weight of cerium oxide and 1% by weight of alumina. The BET surface area was 173 m ² /g. The DBP value is 326 g/100 g of the mixed oxide.

In order to determine the weight ratio (Al ₂ O ₃ /SiO ₂ ) _surface of the original particles in the surface layer having a thickness of about 5 nm, XPS analysis was used. This produced 0.0042 weight ratio of _{(Al 2 O 3 / SiO 2} ) _surface. The measurement of the weight ratio (Al ₂ O ₃ /SiO ₂ ) _ttl in the total primary particles was carried out on the powder by X-ray fluorescence analysis. This gives a weight ratio of 0.010 (Al ₂ O ₃ /SiO ₂ ) _ttl . This produces a value of 2.4 (Al ₂ O ₃ /SiO ₂ ) _ttl /(Al ₂ O ₃ /SiO ₂ ) _surface .

Example 0.2: Conversion of Mixed Oxide Powder to Catalytic Product by Fabrication of Catalyst Extrudate

Mixing 600 grams of pyrolyzed aluminosilicate (1% by mass of Al, calculated as Al ₂ O ₃ ), 24 grams of commercial cellulose ether, and 21 grams as a pressure assist in a mechanical mixer with a needle cyclone A commercial nonionic wax dispersion of the agent, 3 grams of commercial polysaccharide as a plasticizer, 6 grams of a 30% aqueous solution of NH ₃ , and demineralized water. Granulation is then carried out in a mechanical mixer to obtain uniform circular particles having a diameter of about 1 to 3 mm in 30-40 minutes. The wet granules were treated with a commercial extruder to produce a 3 mm extrudate (screw barrel 300 mm, screw diameter 80-64 mm, gear speed 160 rpm, extrusion pressure 31 kg/h). The extrudate obtained in this way was dried in a stream of air at 120 ° C and calcined in air at 600 ° C.

Example 1: Method for treating methanol in the gas phase (according to the invention)

210 g of an extrusion catalyst intermediate mainly composed of pyrolytic aluminum citrate (1 mass% Al) (which can be prepared as described in Examples 0.1 and 0.2) was introduced into a fixed bed reactor (length 206 cm, inner diameter 20.5) Mm), the fluid emerging from which it passes downwards from the top, introducing a bed of inert material (eg glass fragments) 20 cm long as a cooling zone below the catalyst bed and introducing a bed of the same material 30 cm long as a catalyst bed Preheating area. The reactor has a heating jacket utilizing a heat transfer oil (Marlotherm SH from Sasol Olefins & Surfactants GmbH) and a thermostat. The liquid feed stream can be completely evaporated in the evaporator tube if desired.

The reactor that had been fed was closed and the test was leak free and flushed with nitrogen. After two hours, the reactor jacket was heated to 190 ° C while maintaining nitrogen flow. The evaporator was heated to 200 °C. After an additional 2 hours, the nitrogen flow was turned off and methanol treatment was started. For this purpose, 1000 g/h of liquid methanol was continuously conveyed through the experimental apparatus at 7 bar (absolute). This corresponds to a space velocity WHSV of 4.8h ^-1 . The methanol is completely evaporated in the evaporator and the methanol vapor flows through the catalyst to be treated. The composition of the product stream downstream of the reactor was analyzed by gas chromatography and contained only from 1000 to 2000 ppm of dimethyl ether in addition to methanol. The treatment was stopped after 72 hours by stopping the introduction of methanol and flushing the reactor with nitrogen.

After the reactor has been flushed with nitrogen, the cleavage of the ATAE according to the invention can be carried out in the same reactor as described in Example 4.

Example 2: Method for treating methanol in the gas phase (according to the invention)

This was done in a manner completely analogous to Example 1. The only difference is that in this example the processing time is only 24 hours instead of 72 hours.

Example 3: Method for treating methanol in a liquid phase (according to the invention)

The reactor in which 210 g of catalyst had been fed was closed, tested without leakage and rinsed with nitrogen. After two hours, the reactor jacket and evaporator were heated to 115 °C. After an additional 2 hours, the nitrogen flow was turned off and methanol treatment was started. For this purpose, 1000 g/h of liquid methanol was continuously conveyed through the experimental apparatus at 7 bar (absolute). However, the methanol is heated in the evaporator but does not evaporate and flows in a liquid form through the catalyst to be treated. The composition of the product stream downstream of the reactor was analyzed by gas chromatography and contained only 200 ppm of dimethyl ether in addition to methanol. After 24 hours, the treatment was stopped by stopping the introduction of methanol and rinsing the reactor with nitrogen.

After rinsing the reactor with nitrogen and heating to the appropriate temperature, the cleavage of the ATAE according to the invention can be carried out in the same reactor as described in Example 4.

Example 4: Cleavage of MTBE using an untreated catalyst (not according to the invention) or a treated catalyst (according to the invention)

The cracking was carried out in a fixed bed reactor equipped with a heat transfer oil (Marlotherm SH from Sasol Olefins & Surfactants GmbH) through which a heating jacket was passed. Industrial grade MTBE (DRIVERON® from Evonik Industries AG) having a purity of 99.7 mass% was used as the feed.

The MTBE was completely evaporated in the evaporator from 180-270 °C before entering the reactor. At a temperature of 180-270 ° C (at the temperature of the Marlotherm in the feed stream to the reactor jacket) and a pressure of 7 bar (absolute), 1500 g / h of MTBE passes through about 210 g of catalyst, which corresponds to WHSV of 7.1h ^-1 . The gas product mixture was analyzed by gas chromatography. To compensate for the progressive catalyst deactivation, the temperature is continuously increased so that a conversion of 90 to 91% is always achieved.

As the catalyst, the catalysts which have been treated according to the invention from Examples 1 to 3 and the untreated catalysts of the same type are used. In addition, an industrial catalyst (Specialyst 071 from Evonik Industries AG: amorphous magnesium citrate doped with magnesium to reduce activity) was tested. 340 g of this catalyst was used because its activity was significantly less than that of other experimental pyrolytic aluminum silicates.

The isobutene conversion and the selectivity of dimethyl ether formation at various reaction times were calculated from the composition of the feed mixture and the product mixture (DME selectivity = 2 * formed by DME moles versus reacted MTBE moles) and the octene selectivity (number of moles of alkenyl oct-C ₈ = 2 * selectively formed in the MTBE number of the reacted mole). The temperature difference in the reactor was used as a measure of catalyst activity. The cleavage reaction proceeds endothermically, with the result that the temperature measured in the catalyst bed reaches a minimum. Since all experiments were carried out under the same conditions in the same experimental apparatus, the temperature difference between the reactor sheath temperature and the minimum temperature in the catalyst bed was a characteristic parameter related to catalyst activity. In addition, the minimum temperature enables the conclusion that the high boiling point (eg octene) is condensed in the pores. A low temperature difference indicates a risk of low condensation. The results are summarized in Tables 1 to 5.

Interpretation of the results

Experimental results of catalysts not treated in accordance with the present invention are shown in Table 1. It is clear that the catalyst showed very high activity at the beginning of the experiment. A conversion of 94.6% was achieved at a sheath temperature of 190 ° C, and the temperature in the catalyst bed was almost 54 K lower than the jacket temperature. The lowest temperature obtained is 136 ° C and therefore high boiling condensing occurs at a device pressure setting of 7 bar (absolute) in this temperature range, which in particular leads to pressure fluctuations of the device. Furthermore, it is apparent that the formation of diisobutylene (C8) shows an increase in the degree of secondary reaction and a C8 selectivity of more than 4%. For comparison, three experiments (Examples 1 to 3, Tables 3 to 5) using the catalysts treated according to the invention were started under the same conditions (190 ° C, 7 bar (absolute), 1500 g/h MTBE) and It is clear that the activity of the treated catalyst is significantly reduced compared to the untreated catalyst. The catalyst that had been treated according to Example 1 achieved only about 74% MTBE conversion under these conditions. However, this results in a temperature difference in the reactor being reduced to 11 K, with the result that condensation in the pores is no longer expected here. Similar observations were also made in the case of the catalysts treated according to Examples 2 and 3; the conversions at 190 ° C were about 88% and 91%, respectively, and were therefore significantly lower than in the case of untreated catalysts. The conversion and the critical temperature difference in the reactor were only 30 and 40 K, respectively. The resulting minimum temperature also does not cause condensation of high boilers in the pores. The initial C8 selectivity was significantly less than 1% for all treated catalysts, which greatly simplifies the purification of the product stream.

A typical amorphous aluminum silicate doped with magnesium (Table 2) cannot be used at 190 ° C because the activity is too low. Instead, the reaction started at 225 °C. At 92% conversion, this catalyst shows a significant increase in DME selectivity (1.2%) ). However, the C8 selectivity is slightly lower than the C8 selectivity of pyrolytic aluminum citrate (Tables 1 and 3 to 5). The temperature difference when using this catalyst is similar to the temperature difference in the case of the catalyst catalyst which has been treated in accordance with the present invention.

Due to the reduced initial activity, the treated catalyst must start at a higher temperature. Columns B of Tables 1 to 5 make it possible to compare the catalyst to a conversion of about 91%. The pressure and space velocity were not changed. The untreated catalyst was still very active (temperature 190 ° C) and showed C8 selectivity (0.8%) after 54 hours significantly lower than immediately after start-up (4%). Catalysts that have been treated in accordance with the present invention behave significantly differently here. The C8 selectivity is from 0.35 to 0.50% and therefore sometimes only one and a half of the value in the case of untreated catalyst.

The temperature difference in the reactor in the case of untreated catalyst is still critical (49.5 K). The catalyst that has been treated in accordance with the present invention exhibits a significantly smaller temperature difference from 31 to 36K. Because in the case of these catalysts, while increasing the jacket temperature (setting the conversion at 91%), the lowest temperature measured in the reactor is significantly higher than in all without the treated catalyst. The condensation range of the high boilers in the case of the treated catalyst.

The experiment then continued for up to about 1000 hours of experiment in each case, and the conversion was maintained from 90 to 91%. All catalysts are subject to some aging or deactivation, which shows that the jacket temperature of the reactor must be increased to keep the conversion constant. If this aging is checked (columns B to F of Tables 1 to 5), it is found that the untreated catalyst ages to a large extent and must increase by 36K at the jacket temperature (Table 1). On the other hand, the catalyst which has been treated according to Example 1 has significantly reduced aging and temperature and therefore must only increase by 18K. In the case of the catalyst that has been processed according to Example 2, it is necessary to increase 22K. Has The catalyst treated according to Example 3 showed that aging was similar to the aging of untreated materials.

In the operating state after about 1000 hours, all of the pyrolytic aluminum silicate catalysts showed approximately the same performance: the activities were very similar. The sheathing temperature from 90 to 91% conversion was 230 ° C ± 3%. The by-product selectivity is similar. The DME selectivity of the treated catalyst is slightly higher, while the C8 selectivity is as high as 40% lower than the untreated catalyst. The amorphous aluminum citrate here shows, in particular, the difference in activity, which is still so low despite the significantly larger mass of the catalyst, which is 245 ° C and therefore 15 K better than the average of his catalyst. On the other hand, aging is a bit less. DME selectivity is very high at 2.7%, and C8 selectivity is comparable to other catalysts.

In summary, this example shows that highly reactive catalyst materials (such as pyrolytic aluminum citrate with a low proportion of aluminum) have very high initial activity, but undergo considerable aging during the first 1000 hours of operation. It makes these catalysts difficult to use in the factory. Treatment of such materials with methanol in accordance with the present invention can significantly reduce this high initial activity. At the same time, the aging of the material during the first 1000 hours of operation was significantly reduced. After this commissioning period, the activity and selectivity are as good as in the case of the untreated catalysts and significantly better than those of conventional industrial catalysts. The treated catalyst is thus not permanently damaged, so that it can be profitable from its high activity and selectivity in steady state operation without the major problems that must be managed during the start-up phase of the plant (due to condensation in the pores of excessive exotherm) Pressure fluctuations, due to the formation of products other than the specifications for the formation of excess C8).

Claims (16)

A process for the preparation of an aluminum phthalate-containing catalyst intended for the cracking of alkyl tertiary alkyl ethers to form olefins and alcohols, characterized in that the catalyst is treated with methanol prior to use. According to the method of claim 1, wherein the catalyst has the following composition in a total of 100%:矽: from 50 to 99.9% by mass (calculated as SiO ₂ ); Aluminum: from 0.1 to 50% by mass, preferably from 0.1 to 20% by mass, particularly preferably from 0.5 to 11% by mass (calculated as Al ₂ O ₃ ); Alkali metal: from 0 to 15% by mass (calculated as M ₂ O, where M is an alkali metal); Alkaline earth metal: from 0 to 30% by mass (calculated as MO, where M is an alkaline earth metal). The method according to claim 1, comprising the steps of: a) flame hydrolysis preparation of a mixed oxide containing cerium and aluminum; b) converting the mixed oxide into a catalyst intermediate; c) treating with methanol The catalyst intermediates to produce a catalyst. The method of any one of claims 1 to 3, wherein the treatment with methanol is carried out away from the use of the catalyst. The method according to any one of claims 1 to 3, wherein the treatment with methanol is carried out using the catalyst. According to the method of any one of claims 1 to 3, the treatment with methanol is carried out by using a liquid and/or a gas methanol in a catalyst or contact The intermediate is passed through or by immersing the catalyst or catalyst intermediate in a liquid and/or gaseous methanol. The method of claim 6, wherein the space velocity WHSV of the catalyst or catalyst intermediate is from 0.1 to 20 h ^-1 , preferably from 0.5 to 5 h ^-1 when methanol is passed over the catalyst. range. The method of any one of claims 1 to 3, wherein the pressure is in the range of from 0.1 to 1.5 MPa (absolute) in the treatment with methanol, particularly wherein the pressure is from 0.5 to 0.8 MPa. (absolute) range. The method according to any one of claims 1 to 3, wherein the treatment with methanol is carried out at a temperature ranging from 50 to 300 ° C, preferably at a temperature of from 100 to 200 ° C. It is carried out at a temperature of from 115 to 190 °C. A process for the pyrolysis of an alkyl tertiary alkyl ether of formula II to an olefin of formula I and an alcohol of formula III, R-OH III wherein, in the formulae I to III, the R group is an alkyl group having 1 or 2 carbon atoms, the R ¹ group is H or a methyl or ethyl group and R ² and R ³ The groups are each a methyl or ethyl group, wherein the R ² and R ³ groups may be the same or different, characterized in that the cleavage is carried out in the presence of an aluminum phthalate catalyst which has been treated with methanol. The method according to claim 10, wherein the catalyst has a composition of up to 100% in total: 矽: from 50 to 99.9% by mass (calculated as SiO ₂ ); aluminum: from 0.1 to 50% by mass, preferably from 0.1 to 20% by mass, particularly preferably from 0.5 to 11% by mass (calculated as Al ₂ O ₃ ); alkali metal: from 0 to 15% by mass (calculated as M ₂ O, wherein M is an alkali metal); alkaline earth metal: from 0 to 30% by mass (calculated as MO, where M is an alkaline earth metal). The method according to claim 10 or 11, which comprises the following sequential steps: a) introducing a catalyst which has been treated with methanol into the reactor; b) performing the cracking in the reactor. The method according to claim 10 or 11, comprising the following sequential steps: a) introducing a catalyst or catalyst intermediate not treated with methanol into the reactor; b) treating the untreated with methanol in the reactor Catalyst or catalyst intermediate; c) the cleavage is carried out in a reactor. The method of claim 12, wherein the treatment with methanol is carried out under pressure and temperature conditions substantially equivalent to those in the cleavage reaction or in which a catalyst which has been treated under these conditions is introduced. The method according to claim 10 or 11, wherein the methanol is partially or completely substituted with another alcohol (particularly ethanol). The method of claim 10 or 11, wherein the cracking is gas phase cracking of methyl tertiary butyl ether (MTBE) to form isobutylene and methanol.