DE10049873A1 - Production of catalyst with shell of catalytically-active oxide used e.g. in gas phase oxidation of propene to acrolein uses support with ring geometry - Google Patents

Abstract

Production of catalyst with support having ring geometry and shell of catalytically-active oxide (I) containing molybdenum, bismuth, iron plus cobalt and/or nickel and optionally other elements involves producing dry mixture of starting materials for (I), thermal treatment at 150-350 deg C to give precursor mass, moistening support with water, contacting with mass to form coating, drying and calcination at 400-600 deg C. Production of a catalyst with support having ring geometry and shell of catalytically-active oxide of formula (I), containing molybdenum (Mo), bismuth (Bi), iron (Fe) plus cobalt (Co) and/or nickel (Ni) and optionally other elements, by producing intimate dry mixture of starting materials for (I), thermal treatment at 150-350 deg C to give precursor mass, moistening support with water, contacting it with this mass to form coating, drying and calcination at 400-600 deg C. X<1> = cobalt (Co) and/or nickel (Ni); X<2> = silicon (Si) and/or aluminum (Al); X<3> = lithium (Li), sodium (Na), potassium (K), cesium (Cs) and/or rubidium (Rb); a = 0.2-1; b = 2-10; c = 0.5-10; d = 0-10; e = 0-0.5; y = value giving neutral charge, depending on valency and frequency of elements other than oxygen (O). An Independent claim is also included for catalysts produced in this way.

Description

The present invention relates to a process for the preparation of a catalyst which comprises a support body and a catalytically active oxide composition of the general formula I applied to the surface of the support body

Mo ₁₂ Bi _a X ¹ _b Fe _c X ² _d X ³ _e O _y (I)

With
X ¹ = Co and / or Ni,
X ² Si and / or Al,
X ³ = Li, Na, K, Cs and / or Rb,
0.2 ≦ a ≦ 1,
2 ≦ b ≦ 10,
0.5 ≦ c ≦ 10,
0 ≦ d ≦ 10,
0 ≦ e ≦ 0.5 and
y = a number which is determined under the condition of charge neutrality by the valency and frequency of the elements in I different from oxygen,
consists,
in which an intimate dry mixture is produced from starting compounds of the elementary constituents of the catalytically active oxide composition, the intimate dry mixture is thermally treated at a temperature of 150 to 350 ° C. to obtain a precursor composition, the support body is moistened with water, then brought into contact with finely divided precursor composition a layer of the precursor mass is attached to the surface of the moistened carrier body, then the coated carrier body dries and finally the dried, precursor mass-coated carrier body is calcined at a temperature of 400 to 600 ° C.

The present invention further relates to catalysts according to above methods are available and their use for the gas phase catalytic oxidation of propene to acrolein.  

The production of the important intermediate acrolein by heterogeneously catalyzed gas phase oxidation of propene is common my known (see e.g. DE-A 198 55 913).

Acrolein u. a. for the production of acrylic acid, whose alkyl esters, in particular as monomers for the production of aq ger polymer dispersions are used.

It is also known as catalysts for the heterogeneous kataly gated gas phase oxidation of propene to acrolein as catalytic active oxide compositions multimetal oxide compositions of the general formula I use.

For example, DE-A 198 55 913 recommends the use of rings formed from active multimetal oxides I only (Full catalyst rings) as well as the use of spherical Active multimetal oxides I (spherical Shell catalysts) as catalysts for the gas phases Catalytic oxidative production of acrolein from propene.

A disadvantage of the method recommended in DE-A 198 55 913 is wise, however, that on the one hand the mechanical stability of the Full catalyst rings and on the other hand the selectivity and Activity of acrolein formation in the spherical shells catalysts are not fully satisfactory. The same goes for for the spherical coated catalysts of WO 95/26820.

DE-A 44 42 346 relates to the production of annular Shell catalysts of active multimetal oxide materials of the general my formula I. As a liquid binder when applying the active multimetal oxides I recommends DE-A 44 42 346 Use of a solution consisting of 20 to 90 wt .-% water and 10 up to 80% by weight of an organic compound dissolved in water stands. A disadvantage of the ring-shaped coated catalytic converters DE-A 44 42 346 is that their activity and selectivity also relate Lich the formation of acrolein when used as catalysts for the gas phase catalytic partial oxidation of propene not to be peaceful ability.

EP-A 900774 also teaches the manufacture of trays catalysts whose active mass stoichiometry of the general For mel I corresponds.

According to the description of EP-A 900774, the geometry of the Production of the shell catalysts used arbitrarily his. Furthermore, according to the description of EP-A 900774 liquid binders of various types (a  finally water). In the embodiments of the EP-A 900774 are exclusively spherical carrier bodies an aqueous glycerin is always used as the binder solution applied.

The coated catalysts produced in EP-A 900774 are as catalysts for gas-phase catalytic oxidation Recommended by propene to acrolein, but they cannot In terms of their activity still in terms of the selectivity of the Satisfy acrolein formation.

In the earlier application DE-A 199 48 523 are also ringför shell catalysts for gas-phase oxidation recommended by propene to acrylic acid, but the DE-A 199 48 523 no specific processes for their production.

The object of the present invention was therefore a Process for producing a catalyst consisting of a Carrier body and one on the surface of the carrier body brought catalytically active oxide mass, available len, with the shell catalysts are available, which as Shell catalysts with improved activity and increased Selectivity of acrolein formation for gas phase catalytic Oxidation of propene to acrolein are suitable.

Accordingly, a process for the preparation of a catalyst consisting of a support body and a catalytically active oxide composition of the general formula I applied to the surface of the support body

Mo ₁₂ Bi _a X ¹ _b Fe _c X ² _d X ³ _e O _y (I)

With
X ¹ = Co and / or Ni,
X ² = Si and / or Al,
X ³ = Li, Na, K, Cs and / or R _b ,
0.2 ≦ a ≦ 1,
2 ≦ b ≦ 10,
0.5 ≦ c ≦ 10,
0 ≦ d ≦ 10,
0 ≦ e ≦ 0.5 and
y = a number which is determined under the condition of charge neutrality by the valency and frequency of the elements in I different from oxygen,
consists,
in which an intimate dry mixture is produced from starting compounds of the elementary constituents of the catalytically active oxide composition, the intimate dry mixture is thermally treated at a temperature of 150 to 350 ° C., preferably 220 to 280 ° C. to obtain a precursor composition, the support body is moistened with water, thereafter, by contacting finely divided precursor mass on the surface of the moistened carrier body, a layer of the precursor mass is attached, then the coated carrier body dries and finally the dried, precursor mass-coated carrier body is calcined at a temperature of 400 to 600 ° C, found that is characterized in that the carrier body has ring geometry.

The ring-shaped carrier bodies to be used according to the invention are preferably chemically inert, i. that is, they intervene in the process the catalytic gas phase oxidation of propene to acrolein, the by the shell catalysts ka produced according to the invention is essentially not analyzed. As materials for according to the invention, the carrier bodies come in particular aluminum oxide, silicon dioxide, silicates such as clay, kaolin, steatite, pumice, Aluminum silicate and magnesium silicate, silicon carbide, zircon dioxide and thorium dioxide.

The surface of the carrier body can be both smooth and rough. The surface of the support body is advantageously rough, since increased surface roughness generally results in increased adhesion of the applied shell to the catalyst precursor composition or to the oxidic active composition. The surface roughness R _{z of} the carrier body is often in the range from 40 to 200 μm, often in the range from 40 to 100 μm (determined in accordance with DIN 4768 sheet 1 using a "Hommel Tester for DIN-ISO surface measurement values" from Hommelwerke, DE) ,

Furthermore, the carrier material can be porous or non-porous. purpose moderately the carrier material is non-porous (total volume of the Pores based on the volume of the carrier body ≦ 1 vol .-%).

The length of the carrier rings to be used according to the invention is typically 2 to 10 mm and their outer diameter typically 4 to 10 mm. The wall thickness of the carrier rings is usually 1 to 4 mm. Suitable according to the invention Carrier ring dimensions are also 3 to 6 mm (length), 4 to 8 mm (Outer diameter) and 1 to 2 mm (wall thickness). Of course comes into consideration as ring geometry according to the invention 2 to  4 mm (length), 4 to 8 mm (outer diameter) and 1 to 2 mm (wall thickness).

According to the invention distinctive carrier ring geometries are z. B. 7 mm × 3 mm × 1.5 mm (outer diameter × length × wall thickness) and 5 mm × 3 mm × 1.5 mm (outer diameter × length × wall thickness).

The thickness of the shell catalyst obtainable according to the invention active oxide mass is usually 10 up to 1000 µm. But it can also 100 to 700 microns, 200 to 600 microns or 300 to 500 pin. Possible shell thicknesses are also 10 up to 500 µm or 200 to 300 µm.

The fineness of the surface of the ring-shaped carrier body mass to be applied is of course to the Adjusted the desired thickness of the active oxide mass shell. For the A shell thickness of 100 to 500 pin is suitable for. B. Powder from precursor mass, of which at least 50% of the powder particles pass a sieve with a mesh size of 1 to 10 µm and their Proportion of particles with a longest expansion above 50 µm less than 1% (based on the total number of particles) wearing. The distribution usually corresponds to the longest dimension The powder particles are produced in a Gaussian distribution development.

To achieve the desired shell thickness, it is appropriate that to repeat the method according to the invention periodically. That is, the base-coated carrier body then forms in the following Period to be moistened in the manner according to the invention and then by contact with dry, finely divided precursor mass coating "carrier body" etc. The addition of finely divided Precursor mass and binder are usually made continuously ously.

For carrying out the coating to be used according to the invention tion process on a technical scale is therefore recommended. B. the principle of the method disclosed in DE-A 29 09 671.

That is, the support bodies to be coated are expediently inclined (the angle of inclination (angle of the central axis of the container against the horizontal; see FIG. 1, in which 1 = coating drum (side view), 2 = central axis of the drum, 3 = angle of inclination, 4 = horizontal) is ≧ 0 ° and ≦ 90 °, usually ≧ 30 ° and ≦ 90 °) of rotating rotary containers (e.g. turntable or coating drum or kettle).

The rotating rotating container guides the carrier body under two in determined distance on a consecutively arranged dosing directions through. The first of the two dosing devices suitably corresponds to a nozzle (e.g. one operated with compressed air atomizer nozzle) through which the rotating rotary plate rolling carrier body sprayed with water and checked be be moistened. The second metering device is located outside of the atomizing cone of the sprayed in as a binder Water and serves to supply the finely divided precursor mass (e.g. via a shaking channel or powder screw). The control gated, moistened carrier rings take the supplied precursor mass powder, which is due to the rolling movement on the. outer surface of the annular support body to a together menstrual shell compacted (in the inner circle of the hollow cylindrical support body finds such a compacting movement does not take place, which is why this is essentially uncoated remains).

If necessary, the base body coated in this way passes through the Course of the subsequent revolution the spray nozzle again is moistened in a controlled manner so as to continue another layer of finely divided precursor mass to be able to do so etc. (intermediate drying is usually not required).

The removal of the binder to be used according to the invention as water can e.g. B. by supplying heat, e.g. B. by the action of hot gases such as N ₂ or air. Of course, drying can also be done in a drying cabinet. The drying temperature is usually 100 to 150 ° C.

Remarkably, the method according to the invention does so probably a satisfactory liability of successive layers each other, as well as the base layer on the surface of the Carrier body.

Essential for the described form of the Ver driving is that the moistening of the surface to be coated of the carrier body is carried out in a controlled manner. Short expressed this means that the support surface is appropriate so moistened that it has water absorbed, but no liquid phase as such visually in on the carrier surface Appearance occurs. If the surface of the carrier body is too moist, ag glomerates the finely divided precursor mass into separate agglomes guess instead of pulling on the surface. Detailed Anga ben can be found in DE-A 29 09 671.  

An advantage of the method according to the invention is that the removal of the water used as a binder in kon trolled way z. B. can be done by evaporation. In the simple case, this can correspond to the action of hot gases temperature (usually 100 to 150 ° C). By Exposure to hot gases can also only be predried be effective. The final drying can then, for example, in one Any kind of drying oven (e.g. belt dryer).

An essential feature of the method according to the invention is that not the catalytically active oxidic mass on the carrier body as such, but a precursor mass is applied.

The ringför coated with the precursor mass and dried Mige carrier according to the invention for generating the catalytically ak tive oxidic mass can be calcined. This can be done within a period of a few hours (typical calcination times are 2 h to 10 h, the required calcination time with increasing calcination temperature decreases) at temperatures of 400 to 600 ° C, preferably at temperatures of 430 to 500 ° C er consequences.

The calcination can be done either under oxidizing or under inert or in a reducing atmosphere. Conveniently, it takes place in air. It goes without saying that it can also work under vacuum be performed. To generate an inert gas atmosphere NEN z. B. inert gases such as molecular nitrogen and / or Noble gases like He, Ar. The implementation of the calcination can, for. B. done in a forced air oven.

To produce the catalyst precursor mass with which the ring shaped carrier are to be coated according to the invention, one goes usually from sources suitable in a manner known per se of the constituents of the catalytically active, oxidic mass and creates the most intimate, usually fine, from them Partial, dry mixture, which is then at a temperature of 150 to 350 ° C, preferably 220 to 280 ° C, thermally treated will (usually 1 h to 6 h). This thermal treatment can also under inert, reducing or oxidizing At atmosphere. It is usually carried out in air. The at the thermal treatment under which the Quel len usually decompose, resulting precursor mass can then be applied to the carrier rings in finely divided form.

It is essential that it be used according to the invention the sources are either already oxides or such Compounds made by heating, at least in the presence of  Oxygen that can be converted into oxides. Come alongside the oxides therefore primarily ammonium metallates as starting compounds, Halides, nitrates, formates, oxalates, acetates, carbonates or Hydroxides into consideration.

The intimate mixing of the starting compounds can be done in drier or in wet form. It is done in dry form, who which the starting compounds expediently as finely divided Powder used and after mixing and if necessary Pressing thermally treated according to the invention.

However, the intimate mixing is preferably carried out in wet form. The starting compounds are usually in the form of a aqueous solution or suspension mixed together. subsequently, The aqueous mass is dried. This is done with advantage Drying by spray drying (the gas inlet temperature be usually carries 280 to 420 ° C, and the gas outlet temperature is typically 100 to 150 ° C. That at the Spray drying powder proves to be immediate bare further processing often as too fine. In this fall len it can be kneaded with the addition of water. In connection the kneading material is appropriately roughly divided and kneaded dries (e.g. at temperatures from 100 to 150 ° C in the dry closet). Drying can then be carried out according to the invention Connect required thermal treatment at 150 to 350 ° C, before the precursor mass obtained for the Be layering purpose z. B. by grinding into the required fine partial form is transferred.

According to the invention, preference is given to shell catalysts whose catalytically active oxide mass has only Co as X ¹ . Preferred X ² is Si and X ³ is preferably K, Na and / or Cs, particularly preferably X ³ = K.

The stoichiometric coefficient a is advantageous 0.4 ≦ a ≦ 1, particularly preferably 0.4 ≦ a ≦ 0.95. The stoichiometri The coefficient b is preferably in the range 4 ≦ b ≦ 8, and be particularly preferred in the range 6 ≦ b ≦ 8. The value for the variable c is advantageously in the range 1 ≦ c ≦ 5 and with a special prefix part in the range 2 ≦ c ≦ 4. The stoichiometric coefficient is c expediently ≧ 0. Preferred is 0.01 ≦ e ≦ 0.5 and particularly 0.05 ≦ e ≦ 0.2 is preferred.

The value for the stoichiometric coefficient of oxygen, y results from the valence and frequency of the cations under the condition of charge neutrality. Are cheap coated catalysts according to the invention with catalytically active  Oxide masses whose molar ratio of Co / Ni is at least 2: 1, preferably at least 3: 1 and particularly preferably at least 4: 1 is. The best is only Co.

In particularly preferred coated catalysts according to the invention the value for 1.5 × (a + c) + b lies in the range ≧ 11 and ≦ 14, preferably in the range ≧ 11.5 and ≦ 13. Are particularly preferred Values for 1.5 × (a + c) + b in the range ≧ 11.8 and ≦ 12.5.

Furthermore, those shell catalysts according to the invention are according to the invention suitable catalysts whose catalytically active oxide mass is one in the DE-A 198 55 913 specified catalytically active oxide mass ent speaks.

The tray catalysts available according to the invention are proprietary not only for the selective gas phase oxidation of propene Acrolein, but also for partial gas phase oxidation and others rer organic compounds (other alkenes, alkanes, alkanones or alkenols) to α, β-unsaturated aldehydes and / or carbon acids. The production of acrylic acid may be mentioned as an example from acrolein and the production of methacrolein and methacrylic acid from isobutene, isobutane, tert-butanol or tert-butylme dimethyl ether.

The using the coated catalysts according to the invention for the gas phase catalytic oxidation of propene to acrolein General reaction conditions to be observed are found, for. B. in DE-A 40 23 239 and in DE-A 44 31 957.

The coated catalysts according to the invention are particularly suitable to carry out the partial gas phase oxidation of propene Acrolein using increased propene loads Catalyst feed as z. B. in DE-A 199 55 168, in the DE-A 199 48 523 and in DE-A 199 48 248 is described. Wesent Lich is that it increases even with increased propene load Activity and increased selectivity of acrolein formation exhibit.

In conclusion, it should be noted that the gas phase catalytically oxidative propene oxidation to acrolein, According to the invention available shell catalysts as in the EP-A 339119 can be regenerated.  

Examples and comparative examples A) Preparation of A Vorläufermässe the stoichiometry Mo ₁₂ Bi _0.6 Fe ₃ Co ₇ Si _1.6 K _{0, 08} O _x Solution A

To 3530.05 g of an aqueous cobalt (II) -ni heated to 60 ° C. Step solution (12.4 wt.% Co) were over a powder funnel with stirring within one minute while maintaining the 60 ° C 1252.51 g of iron (II) nitrate (14.2 wt .-% Fe) ben. After the addition was complete, the mixture was stirred at 60 ° C. for 30 minutes stirred. Finally, while maintaining the 60 ° C via a dropping funnel within 11 minutes 1198.99 g an aqueous bismuth nitrate solution (11.1 wt .-% Bi) stir. After stirring for ten minutes at 60 ° C, one Obtain clear, red-colored aqueous solution A.

Solution B

10.18 g of an aqueous KOH solution were added to 2500 g of water (46.8 wt .-% KOH) stirred. Then the solution heated to 60 ° C with stirring. Then you gave up maintaining the 60 ° C with stirring in portions 2249.72 g Add ammonium heptamolybdate and stir for another hour 60 ° C after. It became a slightly cloudy, pale yellow aqueous Get solution B.

precipitation

To the aqueous solution B at 60 ° C., the aqueous solution A at 60 ° C. was added with stirring within 15 minutes. After the addition had ended, the mixture was stirred at 60 ° C. for a further 5 min. 204.11 g of silica sol (Ludox®TM, Du Pont, 50% by weight SiO ₂ , density: 1.39 g / ml, pH: 8.8, alkali content ≦ 0.5% by weight) were then added with stirring. added and stirred for another five minutes at 60 ° C.

Spray drying

The aqueous mixture obtained was spray dried in a spray dryer from Niro (spray dryer Niro A / S Atomizer Transportable Minor System, centrifugal atomizer from Niro, DK). The initial temperature was 60 ° C. The gas inlet temperature was 360 ± 10 ° C, the gas outlet temperature was 115 ± 5 ° C. The entire aqueous mixture was sprayed at a flow rate of 2 l / h through a two-fluid nozzle with attached atomizer wheel with a spray nozzle pressure of 5.2 bar with air as the carrier gas (40 m ³ / h) in cocurrent. After powder separation in a cyclone, a spray powder with a particle size of 20 to 25 μm was obtained.

kneading

400 g of the spray powder were in a 1 l kneader from the company Werner & Pfleiderer type LKK 075 with the addition of Knead 44 to 65 ml of water. The kneader had two counter-rotating sigma blades. The kneading took place in three steps that lasted 5, 10 and 15 minutes. Before the third kneading step, the kneaded material was cut up by hand, mixed and detached from the Kent shovels by one to ensure uniform mixing.

desiccation

After the kneading, the kneaded material was roughly divided and for 2 hours in a drying cabinet from the company Bin the, DE, of type FD 53 (53 l internal volume) dry at 120 ° C net.

decomposition

In a convection oven from Nabertherm, DE, type N60 / A (60 l internal volume) the dried kneaded material became thermal treated. The oven was initially started within 2 hours heated to 210 ° C and held at this temperature for 10 min. The mixture was then heated to 250 ° C. within 60 ° C. This Temperature was kept constant for one hour. While the entire process became a gas through the forced air oven flow of 300 Nl / l air. One was received Forerunner mass A.

B) Preparation of a precursor mass B of stoichiometry B Mo ₁₂ Bi _0.2 Fe _4.0 CO ₇ Si _1.6 K _0.08 O _x Solution A '

To 3547.38 g of an aqueous cobalt (II) -ni heated to 60 ° C. Step solution (12.4 wt.% Co) were over a powder funnel while stirring and maintaining the 60 ° C 1678.22 g Iron (II) nitrate (14.2 wt .-% Fe) added within one minute give. After the addition was complete, the mixture was stirred at 60 ° C. for 30 minutes stirred. Finally, it took place within 2 min. the  Add 401.63 g of an aqueous bismuth nitrate solution (11.1% by weight Bi) over a dropping funnel and with stirring at 60 ° C. The mixture was then stirred at 60 ° C for 10 minutes. It a clear red-colored solution A 'was obtained.

Solution B '

10.23 g of an aqueous KOH solution were added to 2500 g of water (46.8 wt .-% KOH) stirred. The aqueous solution was under Stirring heated to 60 ° C. Subsequently, under upright maintaining the 60 ° C with stirring in portions 2260.76 g Ammonium heptamolybdate added. After that was still Stirred for 1 hour at 60 ° C and so a slightly cloudy pale yellow solution B 'obtained.

precipitation

The solution A 'at 60 ° C. was added to the aqueous solution B ′ at 60 ° C. within 15 minutes. added with stirring via a pump. After the addition had ended, the mixture was stirred at 60 ° C. for a further 5 min. Subsequently, while maintaining the 60 ° C., 205.11 g of silica sol (Ludox-®TM, Du Pont, 50% by weight SiO ₂ , density: 1.39 g / ml, pH: 8.8, alkali content ≦ 0.5 % By weight) was added and the mixture was stirred at 60 ° C. for a further five minutes.

Spray drying, kneading, drying and decomposition were on closing as performed under A) and so a precursor received mass B.

C) Production of coated catalysts according to the invention and Comparative coated catalysts General manufacturing characteristics

The precursor mass to be used for the coating was ground in a centrifugal mill (type ZM 100, from Retsch, DE) to a grain size <0 and ≦ 0.12 mm. The grain size distribution is as follows:

Here are:

D = diameter of the grain.
X = the percentage of grains whose diameter is ≧ D.
Y = the percentage of grains whose diameter is <D.

124 g of the ground precursor mass were applied to 250 g of carrier body (R _z = 45 μm, carrier material = steatite, total pore volume of the carrier ≦ 1% by volume (based on total carrier volume). For this purpose, the carrier was placed in a coating drum with a 2 l internal volume, Inclination angle of the center axis of the drum against the horizontal = 30 °). The drum was rotated at 25 revolutions per minute. An atomizer nozzle operated with compressed air was used for 60 min. sprayed away about 45 ml of liquid binder on the carrier. The nozzle was installed in such a way that the spray cone wetted the carrier bodies in the drum, which were carried by driving plates to the uppermost point of the inclined drum, in the upper half of the rolling path. The finely divided precursor mass was introduced into the drum via a powder screw, the point at which the powder was added was within the rolling zone or below the spray cone. Due to the periodic repetition of wetting and powder metering, the base-coated carrier body itself became the carrier body in the subsequent period. After completing the coating, the coated carrier body was dried for 2 hours at 120 ° C. in a drying cabinet (company Binder, DE, internal volume 53 l). The dried shell catalyst precursors were then calcined in a circulating air oven from Heraeus, DE (type K 750/2 S. internal volume 55 l) with air flowing through 800 Nl / h.

For this purpose, the convection oven was opened within 210 min. linear from 25 ° C to 470 ° C warmed. This temperature was then during Maintain for 6 hours. The manufactured in this way Shell catalysts showed an activity in all cases mass layer thickness of 370 ± 30 µm.  

Comparison cup catalyst VS1

The precursor mass A was used, balls were used as carrier bodies a diameter of 2.5 to 3.5 mm used the liquid binder was water;

Shell catalyst S1 according to the invention

Like VS1, as a support body were ever but hollow cylinder with an outside diameter of 7 mm, a length of 3 mm and an inner diameter of 4 mm used;

Comparison cup catalyst VS2

Like S1, as a liquid binder however became a 25% by weight solution Glycerin used in water;

Comparison cup catalyst VS3

Like S1, but for coating not the precursor mass A, but a 6 h at 470 ° C in the above Fan oven (of 800 Nl / h air flowed through) from the Heraeus company calcined precursor mass A used (the heating of the circulating air oven from 25 ° C to 470 ° C took place in within 210 min. through linear Temperature increase). According to the Be layering of the carrier body and Drying pending calcination was omitted.

Comparison cup catalyst VS4

Like VS1, as a precursor mass has ever been but the precursor mass B used;

Shell catalyst S2 according to the invention

Like S1, as a precursor mass has ever been but the precursor mass B used;

Comparison cup catalyst VS5

Like VS2, as a precursor mass has ever been but the precursor mass B is used.  

D) Testing the shell catalysts produced under C.

One reaction tube each was made with the shell catalysts V2A steel (outer diameter = 21 mm, inner diameter = 15 mm) fed. The loading length was so in all cases chooses that the fixed catalyst bed ent 32 to 34 g of active mass held.

The entire length of the reaction tube was covered with an it circulating salt bath tempered. As reaction gas starting mixture was a mixture of 5 vol .-% propene, 9.5 vol .-% oxygen and 85.5 vol .-% nitrogen used. The, burden on the reaction tube res with reaction gas starting mixture was in all cases 100 Nl / h. The salt bath temperature was set in this way in all cases sets that with a single pass through the reaction tube Propene conversion U of 95 mol% was achieved.

The was in the product gas stream by gas chromatography analysis Selectivity S of the product of value on acrolein determined.

U and S are defined as follows:

The following table shows the salt bath temperatures T _s [0 ° C] required with the different shell catalysts (the lower the salt bath temperature required, the higher the catalyst activity) as well as the selectivities achieved in acrolein formation and the exact conversions of propene. The selectivity data are relative selectivity data S _R. That is, within the series of shell catalysts VS1, 51, VS2 and VS3, the selectivity of acrolein formation achieved with VS1 was set to 100 and the selectivity of acrolein formation achieved with the other three shell catalysts was based on this.

Correspondingly, within the range of bowls catalysts VS4, 52 and VS5 the selectivity achieved with VS4 the acrolein formation is set to 100.  

table

Claims (17)

1. A process for the preparation of a catalyst which comprises a support body and a catalytically active oxide composition of the general formula I applied to the surface of the support body
Mo ₁₂ Bi _a X ¹ _b Fe _c X ² _d X ³ _e O _y (I)
With
X ¹ = Co and / or Ni,
X ² = Si and / or Al,
X ³ = Li, Na, K, Cs and / or Rb,
0.2 ≦ a ≦ 1,
2 ≦ b ≦ 10,
0.5 ≦ c ≦ 10,
0 ≦ d ≦ 10,
0 ≦ e ≦ 0.5 and
y = a number which is determined under the condition of charge neutrality by the valency and frequency of the elements in I other than oxygen,
consists,
in which an intimate dry mixture is produced from starting compounds of the elementary constituents of the catalytically active oxide mass, the intimate dry mixture is thermally treated at a temperature of 150 to 350 ° C. to obtain a precursor, the carrier body is moistened with water, then by bringing it into contact with finely divided particles Precursor mass adheres a layer of the precursor mass to the surface of the moistened carrier body, then dries the coated carrier body and finally calcines the dried, precursor mass-coated carrier body at a temperature of 400 to 600 ° C, as characterized in that the carrier body has a ring geometry having. 2. The method according to claim 1, characterized in that the Carrier body made of aluminum oxide, silicon dioxide, clay, kaolin, Steatite, pumice, aluminum silicate, magnesium silicate, silicon carbide, zirconium dioxide or thorium dioxide.   3. The method according to claim 1 or 2, characterized in that the surface roughness R _{z of} the carrier body is 40 to 200 microns. 4. The method according to any one of claims 1 to 3, characterized records that the total volume of the pores of the support body based on the volume of the carrier body is ≦ 1% by volume. 5. The method according to any one of claims 1 to 4, characterized records that the rings have a length of 2 to 10 mm, a Outside diameter of 4 to 10 mm and a wall thickness of 1 to 4 mm. 6. The method according to any one of claims 1 to 4, characterized records that the rings have a length of 3 to 6 mm, a Outside diameter of 4 to 8 mm and a wall thickness of 1 to 2 mm. 7. The method according to any one of claims 1 to 4, characterized records that the rings have a length of 2 to 4 mm, a Outside diameter of 4 to 8 mm and a wall thickness of 1 to 2 mm. 8. The method according to any one of claims 1 to 7, characterized records that the layer thickness of the on the surface of the Carrier body applied catalytically active oxide mass 10th is up to 1000 µm. 9. The method according to any one of claims 1 to 7, characterized records that the layer thickness of the on the surface of the Carrier body applied catalytically active oxide mass 100th is up to 500 µm. 10. A method for producing a catalyst according to one of the Claims 1 to 8, characterized in that the method according to one of claims 1 to 8 in a periodic manner as repeatedly applied, d. that is, the base coated carrier Body forms to moisturize in the subsequent period and then by contact with finely divided precursor mass coating "carrier body" etc. 11. The method according to claim 10, characterized in that the carrier body to be coated in a rotating rotation be filled container, the carrier body periodically under two consecutively arranged dosing devices directions, the first of which are in the rotie The rotating rotating body of the carrier body by spraying  moistened with water and the second the precursor mass in metered in finely divided form. 12. The method according to any one of claims 1 to 11, characterized in that X ^{1 is} exclusively Co. 13. The method according to any one of claims 1 to 12, characterized in that X ^{2 is} exclusively Si. 14. The method according to any one of claims 1 to 13, characterized in that X ^{3 is} exclusively K. 15. Catalyst, obtainable by a process according to one of the Claims 1 to 14. 16. Gas-phase catalytic process. Oxidation of propene too Acrolein, characterized in that a such is used according to claim 15. 17. Use of a catalyst according to claim 15 for gas phase catalytic oxidation of propene to acrolein.