DE19534493A1 - Finely divided shell catalyst prepn. - Google Patents

Abstract

In the prodn. of finely divided shell catalysts by the application of catalytically active material onto a finely divided support and heating this, a fluidised bed is obtd. by passing a gas stream through the finely divided support and contacting the catalytic material with the fluidised finely divided support.

Description

The invention relates to a method for producing fine particles Shell catalysts by applying catalytically active mas sen on finely divided supports and tempering the coated supports and the use of the shell catalysts available in this way the synthesis of aziridines.

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 phosphates 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 catalytic Gas phase dehydration of monoethanolamine to be ethyleneimine wrote.

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 of this type are 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 mentioned literature set described catalysts, so ent there are undesirable levels of oligomers and polymers of Aziridins. In addition, many catalysts are too short Service life.

From the older, unpublished DE application manure 195 14 146.6 shell catalysts are known from a support made of glass and in which the catalytically active Layer connections of elements of alkali metal, alkaline earth metal and / or lanthanide group of the periodic table contains. The catalytically active masses become more common with the help Methods applied to the glass balls, e.g. B. by immersion nation or spray impregnation in a moving drum. With  Using the previously used methods of impregnation fine partial carrier, however, it is practically not possible to uniform coverage of the carrier with a thin layer of to achieve catalytically active mass.

The present invention has for its object a ver to provide better catalyst. This catalytic converter tor is said to relate to aziridine formation from alkanolamines in the Gas phase have a high selectivity and smaller amounts of Oligomeric or polymeric products deliver than the known ones Have catalysts and a long service life.

The object is achieved with a method for Manufacture of finely divided shell catalysts by applying catalytically active materials on finely divided supports and annealing coated carrier when using a gas stream that is passed through finely divided carriers, a fluidized bed testifies and the catalytically active masses with the whirled up finely divided carriers in contact. Subject of the invention is also the use of the shell catalyst available in this way catalysts in the production of aziridines by intramolecular Catalytic dehydration of alkanolamines in the gas phase at temperatures of at least 250 ° C as a dehydration catalyst sator.

Inert materials, for example, are used as finely divided carriers used, whose melting point is above 450 ° C, and the Oxides, nitrides, carbides or metals with a medium Particle diameter of 10 to 1000, preferably 30 to 500 microns are. Examples of such carriers are finely divided silicon dioxide, silicon carbide, silicon nitride, zirconium oxide, aluminum oxide, aluminosilicates, borosilicates and bauxite.

Glass spheres in Be dress. Glass spheres, one of them, are preferably suitable for this have an average pore diameter of at least 10 nm.

The glasses in question should have a thermal and mecha nically stable base for the active catalyst layer. The carrier material should have the largest possible geometric surface have area. In principle, all glass comes as a catalyst carrier varieties in question under the conditions of aziridine synthesis are stable, e.g. B. sodium silicate glass, boron glass, quartz glass and Phosphate glass. Silicate glasses are preferably used. The Backing material can be in various geometric shapes be set, e.g. B. as powder, grit or balls.  

Glasses with pores larger than 10 µm in diameter are made, for example, by making one Melt from glass of table salt and after shaping and the solidification of the glass melt dissolves table salt with water. Suitable carrier materials of this type are commercially available. A suitable type of glass are e.g. B. Siran glasses from Schott. For example, these glasses have pores with a diameter of 60 to 300 µm.

In addition, finely divided metals are suitable as the carrier material preferably in the form of balls. Suitable metals are, for example wise iron and iron alloys, cobalt, nickel, titanium, tungsten, Copper, silver, gold, platinum, thodium, palladium, chrome, molyb dan, vanadium and all types of steel. Except steels for example all alloys of the above Metals as carriers material can be used. The alloys can also be elements of main groups of the periodic table, e.g. B. carbon, Silicon, boron, aluminum, phosphorus, antimony, bismuth, nitrogen, Lithium, sodium, potassium, calcium and / or barium. Preferably iron and its Le are used as the metallic carrier material alloys because these carriers are easily accessible and good in shape are to be bent, which are suitable for catalysts.

The carrier materials can be coated with a Active composition are subjected to a pretreatment. Thereby are, for example, the mechanical properties of the carrier changed, or you get a support surface increased roughness, which reduces the adhesive strength of the active Catalyst mass on the supports is improved. The pre-treatment development of the carrier can, for example, in a calcination, for. B. Heating to temperatures in the range of 100 to 1200 ° C, or in a chemical treatment of the carrier with an acid or a base. The carrier material of the coated catalytic converter is preferably in the form of spheres.

The shell catalysts contain an active layer as the outer layer Catalyst mass from alkali metal, alkaline earth metal and / or Lanthanide compounds. For the dehydration of alkanol Amines suitable catalysts are known for example from 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. Those are preferred Alkali, alkaline earth and / or lanthanide compounds used, which are stable under the conditions of aziridine synthesis and ins special are non-volatile and no volatile compounds form. Examples include phosphates, sulfates, niobates, Tungstates, vanadates, manganates, molybdates, rhenates, titanates and Salts of heteropolyacids. The catalytically active masses ent  hold in addition to the elements of alkali, alkaline earth and / or Lanthanide group of the periodic system if necessary preferably phosphorus and / or transition metals. Examples of sol che catalytically active materials are doped with lithium Tungsten oxide, sodium-doped 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 means at least one element from the Group of alkali and alkaline earth metals stands out, Y one element the group B is Al, Ti, Zr, Sn, Zn and Ce and O is oxygen, be and the indices a, x, y and b indicate the respective atomic ratios specify the elements Si, X, Y and O, where a = 1, x = 0.005-1, y = 0-1 and b has a value represented 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 X _c O _d (IV).

In formula IV, X denotes at least one element from the group of Alkali and alkaline earth metals, P phosphorus, Y at least one ele ment from group B, Al, Si, S, Sc, Ti, Cu, Y, Zr, Nb, Mo, Sn, Sb, La, Ce, Ta, W, Ti, Pb, Bi and Th and O oxygen. The Indices a, b, c and d and the atomic ratios of the elements X, P, Y and O have the following meaning: if a = 1, b = 0.01-3 and c = 0-100, d is a value divided by a, b and c and the Binding state of the individual elements is given. According to the EP-B-0 230 776 has the formula catalytically active compositions

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

in which X is at least one element that consists of 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 is selected, P = phosphorus, X is at least one element consisting of alkali and Alkaline earth metals is selected, O means oxygen and the Indices a, b, c and d represent the atomic ratios of the elements X, P, Y and O and and if a = 1, b = 0.01-6 and c = 0-3 and  d is a value represented by a, b and c and the bond state of respective elements is determined.

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 lanthanide group of the perio systems are used.

The catalytically active masses are fine on each part of the base material is firmly deposited. you will be according to the invention applied to the carrier in a fluidized bed brings.

The catalytically active compositions are preferably in the form of aqueous solutions on the fluidized bed at temperatures of Room temperature sprayed up to 800 ° C, the melting point or beginning of the softening range of the finely divided carrier material, that forms the fluidized bed, always below the respective one Temperature is at which the aqueous solutions are sprayed on the. One can spray the aqueous solutions of the cataly table active masses, however, also within the fluidized bed take by ver the nozzle through which the aqueous solutions ver be sprayed, immersed in the fluidized bed. In contrast to the usual dip impregnation or spray impregnation of Carrier materials obtained in the manufacture of catalysts one by the impregnation of the carrier according to the invention in one Vortex reactor very even and thin layers on the support ger. The layer thicknesses are, for example, 0.1 nm to 150 μm and are preferably 10 nm to 50 µm. To the aqueous solutions to atomize genes of catalytically active materials one, for example, a spray nozzle, which for example consists of a There is a double tube, the output of which tapers conically and at which the aqueous solution through the inner tube and an inert gas to Atomize the aqueous solution through the outer tube of the double jacket pipe is passed.

The catalytically active compositions can be in one or more Steps are applied to the finely divided carrier. So is it is possible, for example, to flow a gas through the fine particles Conduct carrier materials so that a fluidized bed is generated and then spray on phosphoric acid, the carrier  material is always whirled. After that you can get it up to tempera ture of about 150 ° C while maintaining the fluidized bed heat and then minde according to the invention with aqueous solutions least a combination of elements of alkali metal, earth alkali metal and / or lanthanide group of the periodic system impregnate, dry and if necessary calcine. The so he Containing coated catalysts preferably contain a kata lytically active layer, the connections of transition metals or connections of elements of the third to seventh major group of the periodic table contains. As in the manufacture of Catalysts customary can be made in the fluidized bed th catalysts are optionally aftertreated. This After-treatment can, as already mentioned above, in a Calci nation or chemical treatment. At a chemical aftertreatment may still be necessary additional components in the catalytically active layer be brought. In post-treatment, for example mechanical properties and / or the porosity of the shells catalyst can be changed. Post-treatment is done before preferably also in a fluidized bed. As a fluidizing gas at the Manufacture of the shell catalysts are preferably inert Gases into consideration, e.g. B. nitrogen, carbon dioxide, noble gases or Steam.

The production of the shell catalysts by impregnating the finely divided support with catalytically active materials takes place before preferably under atmospheric pressure. However, you can also do this optionally under increased pressure, e.g. B. 2 to 20 bar or below reduced pressure, e.g. B. 10 to 800 mbar. The temperatu ren are preferably chosen so that the water as a solvent agent for the catalytically active layers or for the individual NEN components that form the catalytically active layer the system is removed. The temperatures for manufacture the coating in the fluidized bed is 20, for example up to 800 ° C, preferably 50 ° C to 250 ° C.

Finely divided coated catalysts are obtained which have a thin, au catalytically active layer and a macroporous layer Have crystal structure. Such catalyst structures are we essential for good selectivities in the gas phase synthesis of To achieve aziridines by dehydrating alkanolamines. These catalysts have the advantage in aziridine synthesis that that by short transport routes once formed aziridine in the Desorption from the catalyst surface into the gas phase sequence reactions such as oligomerization of aziridines, be suppressed.  

The finely divided shell catalyst produced according to the invention Sators are used as a dehydration catalyst in the manufacture used aziridines. Aziridines, for example, have formula

in which R¹, R², R³, R⁴ and R⁵ independently of one another H, C₁- bis C₈-alkyl or aryl and R⁵ additionally for benzyl, C₁- to C₈-hydroxyalkyl or C₁- to c₈-aminoalkyl. Formula I should preferably characterize ethyleneimine. In this case hen R¹, R², R³, R⁴ and R⁵ each for H. The compounds of For mel I arise from intramolecular catalytic dehydration sation of alkanolamines of the formula

in which the substituents R¹, R², R³, R⁴ and R⁵ the for it in For mel I have given meaning in the gas phase at tempera tures of at least 250 ° C on the manufactured according to the invention finely divided shell catalysts as dehydration catalysts gate. The temperatures of intramolecular dehydration of Alkanolamines are, for example, 200 to 600, preferably 300 to 500 ° C. The reaction is preferably carried out at normal pressure or in a vacuum, but you can ar at elevated pressure work. The catalysts produced according to the invention are preferably used for the dehydration of monoethanolamine, to produce ethyleneimine. From ethyleneimine one obtains for example by polymerizing polyethyleneimines with under different molecular weights. The polyethyleneimines can be used as a process tools used in the manufacture of paper.

The percentages in the examples mean percent by weight.

example 1

In an electrically heated vortex reactor (length 450 mm, inside diameter 60 mm) were 240 g of silicon dioxide with an average ren particle diameter of 200 microns with the help of a nitrogen streams (200 l / h) whirled at 90 ° C. The fluidizing gas was through a glow plug (length 250 mm, inner diameter 40 mm) preheated. In order to achieve steady-state conditions, the fine-grained Silica whirled for 60 minutes. Then you sprayed inside of 2 hours 360 ml of a phosphoric acid solution containing 8.7 g of 85% Contained phosphoric acid on the fluidized bed. The vertebrate was then removed from the reactor and 2 hours at one Annealed temperature of 500 ° C. The annealed and with phosphorus acid-coated fine-particle silica was then introduced into the vortex reactor and added within 2 hours 90 ° C using an aqueous solution of 6 g of barium acetate and 7.7 g Cesium acetate coated in 360 mm distilled water, being one heats up the silicon dioxide with 200 l nitrogen per hour belte. The fluidized material thus coated was then in another Reactor for 2 hours at a temperature of 500 ° C and then Annealed for 2 hours at a temperature of 1000 ° C.

In order to spray the aqueous solutions, a 640 mm long one Double tube used, the inner tube at the exit to 1 mm Narrowed inside diameter and its outer tube 1 mm distance to Had inner tube. The double pipe (spray nozzle) was from above into the Reactor introduced. The distance of the spray nozzle from the top The limit of the fluidized fluidized material during coating was at least 30 mm. As a result, an optimal spray cone was achieved. Around Generating a fine spray was a spray gas dosage 400 l nitrogen per hour required. The spray gas temperature temperature was 90 ° C.

Example 2

Example 1 was repeated with the only exception that one a previously calcined at 500 ° C silicon dioxide with used an average particle diameter of 200 microns.

Example 3

Example 1 was repeated with the only exception that one instead of 7.7 g of cesium acetate, now use 12 g of cesium acetate sat.  

Example 4

Example 1 was repeated with the only exception that one used a spray nozzle in which the inner tube had an inside had a diameter of 0.5 mm.

Example 5

Example 1 was repeated with the only exception that one the aqueous solution of barium acetate and cesium acetate within sprayed on by 4 hours.

Example 6

Example 1 was repeated with the exception that the Phosphoric acid solution and the solution of barium acetate and cesiuma sprayed acetate at a temperature of the fluidized material of 200 ° C.

Comparative Example 1

1000 g of silicon dioxide with an average particle diameter of 200 microns were at 90 ° C in a rotating drum with 10 revolutions movements per minute. You sprayed within 2 hours 1500 ml of a phosphoric acid solution made by diluting 36.3 g 85% phosphoric acid with distilled water to 1500 ml was placed on the finely divided silicon dioxide. It was then annealed in a reactor at 500 ° C and after cooling in the rotating drum described above at 10 revolutions / min with an aqueous solution of 25 g barium acetate and 32.1 g Sprayed cesium acetate in 1500 ml of distilled water. After that the silicon dioxide thus coated was at 500 and on for 2 hours finally annealed at 1000 ° C for 2 hours.

Example 7 Manufacture of ethyleneimine

In an electrically heated quartz tube with an inside diameter water of 60 mm, 72 ml of the one described in Example 1 were fine partial shell catalyst filled. The catalyst was under a pressure of 50 mbar to a temperature of 410 ° C is heating. After the operating conditions were reached, monoethanol amine at a gas velocity of 20 cm / sec over a metal the flow floor from below through the catalyst bed. The reaction mixture coming from the reactor was over 7 hours which is absorbed by means of 0.1N sodium hydroxide solution and gas chromatographed  analyzed. The monoethanolamine conversion was 50% at one Selectivity of 86% and an ethyleneimine yield of 43%.

Comparative Example 2

Example 7 was repeated with the only exception that one 72 ml of the fine prepared according to Comparative Example 1 partial shell catalyst used. Coming from the reactor The resulting reaction mixture was aqueous over 7 hours 0.1 N sodium hydroxide solution absorbed and analyzed by gas chromatography. The monoethanolamine conversion in this case was 45% Selectivity of 69% and an ethyleneimine yield of 31%.

Claims (7)

1. A process for the preparation of finely divided coated catalysts by applying catalytically active compositions to finely divided supports and annealing the coated supports, characterized in that a fluidized bed is generated with the aid of a gas stream which is passed through finely divided supports, and the catalytically active compositions with the whirled up finely divided carriers in contact. 2. The method according to claim 1, characterized in that one uses inert materials as fine-particle carriers, the Melting point is above 450 ° C, and the oxides, Ni tride, carbide or metals with a medium particle are diameters from 10 to 1000 µm. 3. The method according to claim 1 or 2, characterized in that glass beads are used as finely divided carriers. 4. The method according to claim 1, characterized in that finely divided carriers with an average particle diameter from 30 to 500 µm. 5. The method according to any one of claims 1 to 4, characterized records that the catalytically active materials in the form of sprayed aqueous solutions onto the fluidized bed or directly injected into the fluidized bed. 6. The method according to any one of claims 1 to 5, characterized records that the catalytically active layer in a Thickness from 0.1 nm to 150 µm on the finely divided carriers brings. 7. Use of those obtainable according to claims 1 to 6 Shell catalysts in the manufacture of aziridines by intramolecular catalytic dehydration of alkanol amines in the gas phase at temperatures of at least 250 ° C as a dehydration catalyst.