DE4409310A1 - Shell catalyst, its use in the production of aziridines and process for the production of aziridines - Google Patents

Abstract

The invention concerns a shell-type catalyst comprising a metallic carrier material and a catalytically active layer which adheres firmly thereto, which contains elements of the alkali, alkaline earth and/or lanthanide group of the periodic system of elements and which can be obtained by physical or chemical vapour deposition on the carrier material. The invention further concerns the use of shell-type catalysts and a process for preparing aziridines by the catalytic intramolecular splitting off of water in the gaseous phase from compounds of formula (I), in which R<1>, R<2>, R<3>, R<4> and R<5>, independently of one another, signify H or C1 - C4 alkyl and R<5> additionally stands for cyclohexyl, phenyl, benzyl, C1 - C8 hydroxyalkyl or C1 - C8 aminoalkyl.

Description

The invention relates to coated catalysts made of a metalli carrier material and a cataly table active layer by physical or chemical Vapor deposition under reduced pressure (physical or chemical vapor deposition) on the carrier material is available, the use of coated catalysts in the Production of aziridines and process for the production of azi ridinen by catalytic intramolecular dehydration in the gas phase of alkanolamines of the formula

in which R¹, R², R³, R⁴ and R⁵ independently of one another H or C₁- bis C₈-alkyl or aryl and R⁵ additionally for cyclohexyl, Phenyl, benzyl, C₁- to C₈-hydroxyalkyl or C₁- to C₈-aminoalkyl stands.

From EP-A-0 412 415, palladium catalysts are known which for example by tempering a stainless steel mesh at Tem temperatures up to 1000 ° C and subsequent continuous opening bring palladium as an active component in a vacuum vaporization system with the help of an electron steel the. The monolith catalysts available in this way are used in se selective hydrogenation of triple bonds to double bonds used.

From EP-B-0 166 831 and EP-B-0 172 280 are shell catalysts known that by sputtering of inert carrier materials such as Si silicon dioxide or aluminum oxide with metals such as silver, platinum, Palladium, rhodium and iridium can be obtained. The catalysts are used in the production of isocyanates from N-monosubstituted ten formamides or the synthesis of formaldehyde from methanol used.

EP-A-0 576 944 relates to coated catalysts which are phy sical and / or chemical vapor deposition (physical or chemical vapor deposition) of an alloy on moldings  for example, glass, quartz, ceramic, graphite or metal are. The alloys contain as essential elements for example aluminum, gallium, silicon, germanium, tin, Lead, bismuth, titanium, zirconium, vanadium, chrome, molybdenum, wolf ram, iron, zinc, copper or silver. The so producible Shell catalysts are used for hydrogenation, oxidation and Isomerization reactions used.

For the production of aziridines, in particular ethyleneimine, by Dehydration of alkanolamines in the gas phase are ver different catalysts used. For example, from the SU-A-230 166 discloses ethyleneimine by reaction of ethylene oxide and ammonia to form ethanolamine and dehydration of ethanolamine at temperatures of about 450 ° C with example wise with copper chloride or cobalt-II-chloride To produce calcium phosphate as a catalyst.

From JP-B-50/10593 is the production of ethylene imine Dehydration of ethanolamine in the gas phase on tungsten oxide and oxides of Li, Mg, Ni, Mo, Bi, Sn, Si or Al containing Catalysts known. According to the teaching of WO-A-89/05797 used in the dehydration of ethanolamine in the Gas phase molecular sieves made of aluminum silicates, aluminum phospha ten or silicon aluminum phosphates.

In US-A-4,289,656, US-A-4,301,036, US-A-4,337,175, US-A-4,358,405, US-A-376,732 and US-A-4,477,591 Catalysts based on niobium / tantalum oxide with the addition of alkaline earth metal oxides and / or iron / chromium oxides for the catalytic gas phase Described dehydration of monoethanolamine to ethyleneimine ben.

Other catalysts for intramolecular elimination of water Alkanolamines in the gas phase are oxide masses that are silicon or Contain phosphorus as essential components. Catalysts This type is described, for example, in EP-B-0 227 461, EP-B-0 228 898 and EP-B-0 230 776.

If one sets the above in the production of aziridines called catalysts described, so ent there are undesirable levels of oligomers and polymers of Aziridins. In addition, many catalysts are too short Service life.

The present invention is therefore based on the object to provide a new catalyst. That Kataly sator should with regard to aziridine formation from alkanolamines in the  Gas phase have a high selectivity and smaller amounts of deliver oligomeric or polymeric products than the known ones Have catalysts and a long service life.

The object is achieved with a shell catalyst sator made of a metallic carrier material and a solid adhering catalytically active layer, which by physical or chemical vapor deposition with reduced Pressure (physical or chemical vapor deposition) on the carrier material is available if the catalytically active layer Ele elements of the alkali, alkaline earth and / or lanthanide group of Pe contains periodic system.

The invention also relates to the use of the shells catalysts in the production of aziridines by catalyti intramolecular elimination of water in the gas phase Compounds of the formula

in which R¹, R², R³, R⁴ and R⁵ independently of one another H or C₁- bis C₈-alkyl or aryl and R⁵ additionally for cyclohexyl, Phenyl, benzyl, C₁- to C₈-hydroxyalkyl or C₁- to C₈-aminoalkyl stands. The substituents R¹, R², R³, R⁴ and R⁵ can also be used for are a C₃ to C₈ cycloalkyl group, for. B. cyclopropyl, cyclo hexyl, cyclopentyl or cyclooctyl.

Another object of the invention is a method for Preparation of aziridines of the formula

in which R¹, R², R³, R⁴ and R⁵ independently of one another H or C₁- bis C₈-alkyl or aryl and R⁵ additionally for cyclohexyl, Phenyl, benzyl, C₁- to C₈-hydroxyalkyl or C₁- to C₈-aminoalkyl stands by intramolecular dehydration of compounds of the formula  

in which the substituents R¹, R², R³, R⁴ and R⁵ the for it in For mel II have meaning given on solid catalysts in the Gas phase, wherein the dehydration on a fiction carries out appropriate shell catalyst or a shell catalyst sator, which is made by impregnating metallic supports materials with a catalytically active composition is available, the elements of the alkali, alkaline earth and / or lanthanide group of the periodic table. All substituents in formula II can represent a C₃- to C₈-cycloalkyl group, for. B. Cyclo pentyl or cyclohexyl.

The coated catalysts according to the invention consist of a me metallic carrier material. This can be molded articles a single metal or alloy. The metalli cal carrier material is under the conditions of the intramolecular ren catalytic elimination of water from alkanolamines dimensionally stable. It forms an inert, thermally and mechanically stable base for the catalytically active layer. The carrier material is said to be a have the largest possible geometric surface. For the metalli backing materials come as geometric shapes, for example white powder, grit, balls, wires, stretch plates, nets, Woven fabrics, nonwovens, foils, perforated foils and chips. The carrier materials are preferably used in the form of Ge weave or films that may be perforated. Such Shaped bodies can ver very well to monolithic catalysts be shaped. As is well known, monolithic metallic ones enable Catalysts a very high catalyst load with low Pressure loss, a good mixing of the reactants like quick heat and heat dissipation.

Suitable metallic carrier materials are metals of the minor group such as iron, cobalt, nickel, titanium, tungsten, Copper, silver, gold, platinum, rhodium, palladium, chrome, molyb dan, vanadium, zirconium and all types of steel. Except steels can, for example, all alloys of the above metals can be used as carrier material. The alloys can for example, elements from main groups of the periodic table included, e.g. B. carbon, silicon, boron, aluminum, phosphorus, Antimony, bismuth, nitrogen, lithium, sodium, potassium, calcium, Magnesium and / or barium. Preferably used as metal carrier material iron and iron alloys, because these  Carriers are easily accessible and can be shaped well are suitable for catalysts.

The metallic carrier material can, if necessary, before loading layering with a catalytically active layer of a pretreatment be subjected. Such pretreatment can e.g. B. in calcination, chemical treatment with an acid or a lye or in a plasma treatment (rare gas plasma or reaction gas plasma). It increases the roughness speed of the carrier surface, which increases the adhesive strength of the increased catalytically active layer, which is applied thereon.

A firmly adhering kataly is on the metallic carriers table active layer by physical or chemical Deposition over the vapor phase under reduced pressure brings. Coming as material for the catalytically active layers all compounds considered for the intramolecular Elimination of water from the compounds of the formula I in the Literature are described, cf. the above to the prior art References SU-A-230 166, JP-B-50/10593, WO-A-89/05797, EP-B-0 227 461, EP-B-0 228 898 and EP-B-0 230 776. Such alkali, alkaline earth and / or Lan are preferred thanidene compounds used in the conditions of Azi ridin synthesis are stable and in particular are not volatile and do not form volatile compounds. Examples of this are Phosphates, sulfates, niobates, tungstates, vanadates, manganates, Molybdates, rhenates, titanates and salts of heteropolyacids. The In addition to the elements of Al, catalytically active compositions contain Potash, alkaline earth and / or lanthanide group of the Periodic Sy stems preferably phosphorus and / or transition metals. Examples for such catalytically active materials are doped with lithium Tungsten oxide doped with calcium tungstate, with cesium or barium-doped iron sulfate or nickel sulfate.

Catalytically active materials are used, for example, in the EP-B-0 227 461 characterized by the following formula

Si _a X _x Y _y O _b (III),

in which Si means silicon, X consists of at least one element the group of alkali and alkaline earth metals, Y is an element from the group B, Al, Ti, Zr, Sn, Zn and Ce and O is oxygen, means and the indices a, x, y and b the respective atom specify ratios of the elements Si, X, Y and O, where if a = 1, x = 0.005-1, y = 0-1 and b has a value that is given by a, x and y is determined.  

According to EP-B-0 228 898, the catalytically active compositions have the composition

X _a P _b Y _c O _d (IV),

in which X denotes at least one element selected from alkali and Alkaline earth metals. P is phosphorus, Y is at least one element is selected from B, Al, Si, S, Sc, Ti, Cu, Y, Zr, Nb, Mo, Sn, Sb, La, Ce, Ta, W, Ti, Pb, Bi and Th, O is oxygen and the Indices a, b, c and d represent the atomic ratios of the elements X, P, Y and O and, if a = 1, b = 0.01-3 and c = 0-100 and d is a value by a, b and c and the bond state of individual elements and according to EP-B-0 230 776 the formula

X _a P _b Y _c O _d (V),

in which X is at least one element selected from elements of the Group IIIA, elements of group IVA, elements of group VA, Transition metal elements of groups I to VIII, lanthanide and Actinide elements of the periodic table, P is phosphorus, Y minde is at least one element selected from alkali and alkaline earth metals, O means oxygen and the indices a, b, c and d are Atomic ratios of the elements X, P, Y and O are given and if a = 1, b = 0.01-6 and c = 0-3 and d is a value, be agrees with a, b and c and the binding state of the respective Elements.

Further suitable catalytically active compositions are those from US-A-4,337,175, US-A-4,289,656, US-A-4,301,036, US-A-4,337,175, US-A-4,358,405, US Pat. A-4 376 732 and US-A-4 477 591 known oxides of tantalum or niobium with an alkaline earth metal oxide as a promoter. Also suitable are catalysts of the composition M₁₀Fe _0.5-2.9 Cr _0.3-1.7 or M₁₀Fe _1.0-2.1 Cr _0.6-1.7 with M = niobium, tantalum.

Instead of alkaline earth metal oxides, alkali metal oxides can also be used and or oxides of elements of the lanthamid group of the Periodi system.

The catalytically active masses are characterized by physical or chemical vapor deposition with reduced Pressure on the backing material firmly adhered. These Methods are known in the literature as physical vapor deposition (PVD) or chemical vapor deposition (CVD), cf. R.F. Bhunshah et al., Deposition Technologies for Films and Coa tings, Noyes Publications, 1982 and P. Wirz, vacuum technology, 38, 208-214 (1989). Known PVD processes are vapor deposition Cathode sputtering, which in technical parlance as  Is called sputtering, and the arc coating. Be Known CVD processes include thermal and plasma sub supported coating. These procedures are of importance, for example tion to release phosphorus from organophosphorus and in to incorporate an active catalyst layer.

The catalytically active materials can have a layer thickness of 0.1 nm to 10 microns, preferably from 1 nm to 1 micron on the metallic cal carrier material are applied. Of particular advantage are shell catalysts in which the metallic support material is a net, a fabric or a film, and in which the catalytically active layer by sputtering (Sputtering) has been applied. The carrier material is made preferably of a single metal or its alloys. For example, it can be made from transition metals or their alloys conditions exist. The coated catalysts according to the invention are preferably by sputtering elements or their Compounds, especially their oxides. Hereby manages to be one of several components in a simple manner apply standing layer on the metallic support or then to deposit layers of different compositions.

Furthermore, the microstructure of the coating can be influenced by sputtering by varying the process gas pressure and / or by applying a negative bias (bias). For example, a process gas pressure in the range of 4 · 10 ^-3 to 8 · 10 ^-3 mbar leads to a very dense, fine-crystalline layer with high corrosion stability. If a negative bias voltage is applied during the coating process, this results in an intensive ion bombardment of the metallic carrier to be coated, which generally results in a denser layer and improved adhesion of the active catalytically active layer on the metallic carrier.

In cathode sputtering, the coating material, ie the catalytically active composition, is generally applied in the form of a so-called target to the cathode of a plasma system, then under reduced pressure, for example from 1 × 10 ^-4 to 1 mbar, preferably 5 × 10 ^-4 to 5 · 10 ^-2 mbar, atomized in a process gas atmosphere by applying a plasma and deposited on the substrate to be coated, anode, ie the metallic support. In general, at least one noble gas such as helium, neon or argon, preferably argon, is selected as the process gas. The plasma usually consists of charged (ions and electrons) and neutral (sometimes radical) components of the process gas, which interact with one another via shock and radiation processes.

Various methods can be used to produce the coatings variants of cathode sputtering such as magnetron sputtering, DC and RF sputtering or bias sputtering and their combinations be applied. Magnetron sputtering is in the Rule the target to be atomized in an external magnetic field, which concentrates the plasma in the area of the target and thus increasing the atomization rate. With the DC or RF sputtering is generally the excitation of the atomization splasmas by a direct voltage (DC) or by an alternation voltage (RF), for example with a frequency in the range of 10 kHz to 100 MHz, preferably 13.6 MHz. Bias sputtering is usually the substrate to be coated with a in the Usually negative bias (bias) is evidenced, which in general during the coating to an intense bombardment of the sub leads strats with ions.

Zer to produce the coated catalysts according to the invention you generally dust a multi-component target, or two or more targets of different compositions at the same time (simultaneous atomization) or one after the other. The desired Layer thickness as well as the chemical composition and the micro The structure of the layer is essentially due to the process gas pressure, the atomization performance, the sputtering mode, the substrate influence temperature and coating time. The Zer Dusting performance is the performance that stimulates the Plasmas is used, and is usually in the range of 50 W to 10 kW.

The substrate temperature is generally chosen in the range from Room temperature to 350, preferably from 150 to 250 ° C.

The coating time essentially depends on the desired Layer thickness. Typical coating rates for sputtering are usually in the range of 0.01 to 100 nm / s.

Another preferred embodiment is the production of coatings by vapor deposition (see L. Holland, Vacuum Deposition of Thin Films, Chapman and Hay Ltd., 1970). The coating material is expediently in a known manner in a suitable evaporation source such as electrically heated evaporator boat or filled electron beam evaporator. The coating material is then evaporated under reduced pressure, usually in the range from 10 ^-7 to 10 ^-3 mbar, the desired coating being formed on the metallic supports introduced into the vacuum system.

Evaporation can be used in the production of multi-component layers material either in the appropriate composition a common source or simultaneously from different sources be evaporated.

Typical coating rates during evaporation are in general in the range from 1 nm / s to 10 µm / s.

In one embodiment, the substrate to be coated can be pre-coated or during the vapor deposition process using an RF plasma or be bombarded with ions using a conventional ion gun, to improve the microstructure and the adhesion of the layers. Furthermore, the microstructure and the adhesion of the Also affect layers by heating the substrate.

The shell catalysts can, for example, also be transition metals contained in the catalytically active mass. This about Gear metals are preferably contained in the carrier material transition metals different. Of technical importance are also shell catalysts in which the catalytically active tive mass contains phosphorus and those in which the cataly table active mass connections of main group elements of the 3rd to 7th main group contains.

The shell catalysts described above can optionally still to be treated. The aftertreatment can, for example consist of calcination or chemical treatment. In the case of chemical aftertreatment, if necessary additional components inserted into the catalytically active layer be brought. In post-treatment, for example mechanical properties and / or the porosity of the shells catalyst can be changed.

The shell catalysts described above are used in the Production of aziridines by catalytic intramolecular Elimination of water from compounds of the formula I in the gas phase used. Aziridines of the formula II given above are obtained. The preparation of the unsubstituted is particularly preferred Aziridins (ethyleneimine). The temperatures at the intramolecular Ren dehydration of alkanolamines, for example 200 to 600, preferably 300 to 500 ° C. Preferably one leads the reaction at normal pressure or in vacuum, you can depending but also work with increased pressure. When working under normal pressure is the dilution of the compounds of formula I with inert  gases such as B N₂, noble gases, H₂O etc. advantageous. The coated catalysts according to the invention can, for example, in Form of nets, fabrics or perforated foils stationary in one tubular reactor can be arranged. However, you can also in Form of a fine powder or granulate in one flow bed reactor, in a shell reactor or in a fluidized bed reactor are used.

The active catalyst compositions described above can also by precipitation on a metallic carrier material or by Impregnation of a metallic carrier material, preferably by spray impregnation. The so obtained Coatings are not as adherent to the substrates as that using the PVD or CVD process catalysts. The impregnation or precipitation on metal supported catalysts are also used as shells to address catalysts and can be used as a catalyst in the Production of aziridines by intramolecular catalytic Elimination of water from compounds of the formula I can be used. They are particularly suitable for the production of ethyleneimine as a catalyst.

From ethyleneimine, for example, polyethyleneimines with under different molecular weights. The polyethyleneimines are Process aids in the manufacture of paper.

Examples Manufacture of coated catalysts

Steel mesh from Kufferath used. The material numbers are given in the examples.

example 1

A steel mesh, tempered at 900 ° C, material number 1.4767 (mesh size = 180 µm, wire gauge = 112 µm) was placed in a cathode sputtering system. A pressed target made of Ca phosphate of the composition 30.7% Ca, 23.7% P, 0.11% Na, balance O was introduced at a distance of 56 mm. The system was evacuated to a pressure of 10 ^-6 mbar using a two-stage pump system. Thereafter, argon was admitted to a pressure of 5 × 10 ^-3 mbar. By applying an RF voltage to the carrier with an output of 250 W, the carrier was subjected to a sputter etching treatment for 1 min. After the end of the etching treatment, the Ar pressure was set to 5 × 10 ^-3 mbar. A 50 nm thick layer was deposited on the front of the metal mesh by applying an RF voltage of 500 W to the target. The back of the fabric was then coated in the same way.

Example 2

A steel mesh annealed at 900 ° C, material number 1.4767, (mesh size = 180 µm, wire gauge = 112 µm) was placed in a cathode sputtering system. A pressed target made of Ca phosphate of the composition 30.7% Ca, 23.7% P, 0.11% Na, balance O was introduced at a distance of 56 mm. The system was evacuated to a pressure of 10 ^-6 mbar using a two-stage pump system. Thereafter, argon was admitted to a pressure of 5 × 10 ^-3 mbar. By applying an RF voltage to the carrier with an output of 250 W, the carrier was subjected to a sputter etching treatment for 1 min. After the end of the etching treatment, oxygen was let in with a partial pressure of 5 × 10 ^-4 mbar, the Ar pressure being set to 5 × 10 ^-3 mbar. By applying an RF voltage of 500 W power to the target, a 50 nm thick layer was deposited on the front of the metal fabric. The back of the fabric was then coated in the same way.

Example 3

Example 1 was repeated with the exception that the layer thickness of the catalytically active mass on the support was 200 nm.

Example 4

Example 2 was repeated with the exception that the layer thickness of the catalytically active mass on the support was 200 nm.

Example 5

Example 1 was repeated with the exception that a metal network from material number 3.0280.

Example 6

Example 1 was repeated with the exception that a metal network from material number 1.4541.  

Example 7

Example 1 was repeated with the exception that a metal network from material number 1.4310.

Example 8

A steel mesh (material number 1.4767) was placed in a cathode sputtering system. A pressed target of Ca phosphate of the composition 30.7 Ca, 23.7% P, 0.11% Na, balance O was introduced at a distance of 56 mm. The system was evauated to a pressure of 10 ^-6 mbar using a two-stage pump system. Thereafter, argon was admitted to a pressure of 5 × 10 ^-3 mbar. By applying an RF voltage to the carrier with an output of 250 W, the carrier was subjected to a sputter etching treatment for 1 min. After the completion of the etching treatment, oxygen was let in with a partial pressure of 5 × 10 ^-4 inbar, the Ar pressure was set to 5 × 10 ^-3 mbar. By applying an RF voltage of 500 W to the target, a 50 nm thick layer was deposited on the front of the metal mesh. The back of the fabric was then coated in the same way. The catalyst was then heated at 900 ° C.

Example 9

A steel net annealed at 900 ° C (material number 1.4767) was placed in a vapor deposition system. The evaporation plant contained an evaporator device with two controllable, resistance-heated evaporator boats. In one of the two boats fine-grained (Ca-PO) powder with the composition 30.7% Ca, 23.7% P, rest O was poured. (Ca-O) powder was poured into the second boat. The system was evacuated to a pressure of 10 ^-5 mbar using a two-stage pump system. In the vacuum chamber was O₂ sen with a partial pressure of 5 × 10 ^-4 mbar. The evaporator boats were then heated, an evaporation rate of 10 nm / min from boat 1 and an evaporation rate of 20 nm / min from boat 2 being set. A 50 nm thick layer was thereby deposited on the carrier.

Claims (7)

1. coated catalyst from a metallic support material and a firmly adhering catalytically active layer which is obtainable by physical or chemical deposition via the vapor phase under reduced pressure (physical or chemical vapor deposition) on the support material, characterized in that the catalytically active layer Contains elements of the alkali, alkaline earth and / or lanthanide group of the periodic table. 2. coated catalyst according to claim 1, characterized in that the metallic carrier material is a mesh, a fabric or is a film and that the catalytically active layer on it has been applied by sputtering. 3. coated catalyst according to claim 1 or 2, characterized records that the carrier material from a single metal or its alloys. 4. coated catalyst according to one of claims 1 to 3, characterized characterized in that the catalytically active mass transition contains metals. 5. coated catalyst according to one of claims 1 to 4, characterized characterized in that the catalytically active mass compounds of main group elements of the 3rd to 7th main group contains. 6. Use of the coated catalysts according to one of claims 1 to 5 in the production of aziridines by catalytic intramolecular elimination of water in the gas phase from compounds of the formula (I) in which R¹, R², R³, R⁴ and R⁵ independently of one another are H or C₁- to C₈-alkyl or aryl and R⁵ additionally represents phenyl, benzyl, C₁- to C₈-hydroxyalkyl or C₁- to C₈-amino alkyl. 7. Process for the preparation of aziridines of the formula in which R¹, R², R³, R⁴ and R⁵ independently of one another are H or C₁- to C₈-alkyl or aryl and R⁵ additionally represents cyclohexyl, phenyl, benzyl, C₁- to C₈-hydroxyalkyl or C₁- to C₈-aminoalkyl, by intramolecular dehydration of compounds of the formula in which the substituents R¹, R², R³, R⁴ and R⁵ have the meanings given for this in formula II, on solid catalysts in the gas phase, characterized in that the dehydration is carried out on a coated catalyst according to one of claims 1 to 5 or a coated catalyst uses, which is obtainable by impregnating metallic support materials with a catalytically active composition which contains elements of the alkali, alkaline earth and / or lanthanide group of the periodic table.