EP2696969A1

EP2696969A1 - Process for producing a catalyst for the oxidation of ethylene to ethylene oxide

Info

Publication number: EP2696969A1
Application number: EP12772032.4A
Authority: EP
Inventors: Tobias Rosendahl; Torsten Mäurer; Cornelia Katharina Dobner
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2011-04-14
Filing date: 2012-04-13
Publication date: 2014-02-19
Also published as: CN103596677A; WO2012140613A1; JP2014512949A; EP2696969A4

Abstract

Disclosed a shaped catalyst body for preparing ethylene oxide, which comprises at least silver and rhenium applied to an alumina support, and also a process for producing it, wherein the alumina support has the geometry of a hollow cylinder and the shaped catalyst body has a rhenium content C_R and C_R/ppm by weight, based on the wall thickness of the hollow cylinder d_w in mm, and calculated as element, in the range 120≤C_R/d_w≤200.

Description

Process for preparing a catalyst for the oxidation of ethene

ethylene oxide

The present invention relates to a shaped catalyst body for the production of ethylene oxide, comprising at least silver and rhenium applied to one

Aluminum oxide, wherein the alumina support has the geometry of a hollow cylinder and wherein the shaped catalyst body has a rhenium content C _R and C _R /Gew.-ppm, based on the wall thickness of the hollow cylinder d _w / mm, in the range of 120 <C _R / d _w ^ 200 lies. Furthermore, the invention relates to a process for the preparation of this molding and the use of this molding as a catalyst for the conversion of ethene to ethylene oxide.

Ethylene oxide is an important basic chemical and is widely used industrially

Direct oxidation of ethene with oxygen in the presence of silver-containing

Catalysts produced. Mostly alumina supported catalysts are used in which the catalytically active metallic silver has been applied to an alumina support by a suitable method. In principle, various porous materials such as activated carbon, titanium oxide, zirconium oxide, silicon dioxide, aluminum oxide or ceramic compositions or mixtures of these materials can be used as the alumina support material. Particularly preferred alumina carriers are based on alpha alumina. Exemplary of the direct oxidation of ethene are DE-A-2300512, DE-A 2521906, EP-A-0014457, DE-A-2454972, EP-A-0172565, EP-A-0357293, EP-A-0266015, EP -A-001 1356, EP-A-0085237, DE 2560684 or DE-A-2753359.

In order to improve the activity and / or the selectivity of the catalysts in the oxidation of ethene to ethylene oxide, promoters are also applied to the alumina support in addition to the active material silver. Examples are alkali and / or

Called alkaline earth metal compounds, tungsten, molybdenum or rhenium, with a particularly preferred promoter being rhenium. The term "selectivity" is understood to mean the percentage of ethene used in the process, which is converted to ethylene oxide during the oxidation.With regard to the activity of the catalyst, the activity of the catalyst is higher, the lower the Reaching a predetermined concentration of ethylene oxide at the reactor outlet temperature required at otherwise constant reaction conditions.

In order to influence the activity and / or the selectivity of such catalysts, various measures are disclosed in the prior art documents.

Thus, US 2004/0260103 A1 describes influencing the activity of a catalyst by changing the geometry of the catalyst. In this context, catalysts in the form of hollow cylinders with a ratio of Outer diameter to the wall thickness in the range of 0.3 to 2 mm described as advantageous, the wall thickness being greater than commonly used

Hollow cylinders is selected. An increase in the rhenium concentration when increasing the wall thickness is not described.

EP 1 613 428 B1 describes a process for converting ethene to ethylene oxide, in the presence of a catalyst, of rhenium in an amount of at most 1.5 mmol / kg, based on the total weight of the catalyst and at most 0.0015 mmol / m ² , based on the BET surface area of the carrier. The lower initial selectivity resulting from the small amount of rhenium in the

Epoxidation reaction is compensated by gradually increasing the temperature during the epoxidation reaction. According to EP 1 613 428 B1, the catalysts described there should have a longer service life compared to those with a higher rhenium content.

An object of the present invention was to provide advantageous catalysts for the oxidation of ethene to ethylene oxide.

Surprisingly, it has been found that shaped catalyst bodies in which at least silver and rhenium on one have the geometry of a hollow cylinder

Alumina carriers have been applied and have a rhenium content C _R , wherein C _R /Gew.-ppm, based on the wall thickness of the hollow cylinder dw / mm, in the range of 120 <C _R / d _w ^ 200, advantageous selectivities and / or activities in the conversion of ethene to ethylene oxide. When changing the geometry of a catalyst were thus surprisingly by adjusting the

Rhenium concentration (increase in concentration when increasing the wall thickness), with otherwise constant composition, catalysts having particularly advantageous catalytic properties in the oxidation of ethene to ethylene oxide obtained. Therefore, the present invention also relates to a shaped catalyst body for the production of ethylene oxide, comprising at least silver and rhenium supported on an alumina support, wherein the alumina support has the geometry of a hollow cylinder and wherein the shaped catalyst body has a Rheniumgehalt C _R and C _R /Gewppppm, based on the wall thickness of the hollow cylinder dw / mm, in the range of 120 <C _R / d _w ^ 200.

Likewise, the present invention also relates to a process for the preparation of a shaped catalyst body, and to a catalyst shaped body producible or produced by this process, the process comprising:

(a) providing an alumina support having the geometry of a hollow cylinder,

(b) depositing silver and rhenium on the alumina support, wherein rhenium is present in an amount of C _R / wt ppm, based on the wall thickness of the hollow cylinder dw / mm, and calculated as an element which is in the range of 120 <C _R / d _w 200 200, is applied to the alumina support.

disk geometry

According to the present invention, the alumina carrier is in the form of a hollow cylinder. The exact dimensions of this hollow cylinder are generally from

subordinate importance. Conveniently, however, the hollow cylinders should have a size that allows unimpeded diffusion of the reaction gases to the largest possible part of the catalytically active, with silver particles and

optionally allow with other promoters occupied outer and inner surface of the alumina carrier.

In particular, the hollow cylinders have a length in the range of 5 to 10 mm, an outer diameter in the range of 5 to 10 mm and a ratio of

Outside diameter / mm to wall thickness / mm in the range of 2.5 to 4.5 on. By way of example, the following geometries of hollow cylinders which are particularly preferred for the purposes of the invention may be mentioned (outer diameter x length x inner diameter, in each case given in mm): 5x5x2, 6x6x3, 7x7x3, 8x8x3, 8x8.5x3, 8x8.5x3.5, 8.5x8x3, 5, 8,5x8x3, 9x9x3, 9,5x9x3, 9,5x9x3,5, each of these length specifications including tolerances in the range of ± 0,5 mm.

Accordingly, the present invention relates to a shaped catalyst body, as described above and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body produced or produced by this method, as described above, wherein the shaped catalyst body has the geometry of a hollow cylinder and wherein the hollow cylinder a Length L in the range 5 to 10 mm, an outer diameter d _A in the range of 5 to 10 mm and a ratio of

Outer diameter d _A / mm to wall thickness d _w / mm in the range of 2.5 to 4.5.

Preferably, the hollow cylinder has a length in the range of 6 mm to 9.5 mm, more preferably in the range of 6 mm to 9 mm, and particularly preferably a length in the range of 6 mm to 8.5 mm. Preferably, the hollow cylinder has an outer diameter in the range of 6 mm to 9.5 mm, more preferably in the range of 6 mm to 9 mm, and particularly preferably an outer diameter in the range of 6 mm to 8.5 mm.

Preferably, the hollow cylinder has a length in the range of 6 mm to 9.5 mm and an outer diameter in the range of 6 mm to 9.5 mm, more preferably a length in the range of 6 mm to 9 mm and an outer diameter in the range of 6 mm to 9 mm, and more preferably a length in the range of 6 mm to 8.5 mm and an outer diameter in the range of 6 mm to 9 mm, on. The ratio of outside diameter d _A / mm to wall thickness d _w / mm is preferably in the range of 3.0 to 4.0. Rhenium amount

As regards the amount of rhenium C _R , the catalyst preferably contains rhenium in an amount of 210 ppm by weight to 540 ppm by weight, more preferably in an amount of 250 ppm by weight to 510 ppm by weight, more preferably in an amount of 280 ppm by weight to 480 ppm by weight, and more preferably in an amount of 300 ppm by weight to 450 ppm by weight, based on the total weight of the catalyst and calculated as element, wherein C _R / Gewpppp, based on the wall thickness of the hollow cylinder dw / mm, in the range of 120 <C _R / d _w ^ 200.

Preferably, C _R / wt ppm, based on the wall thickness of the hollow cylinder dw / mm, in the range of 1 15 <C _R / d _w ^ 200, more preferably in the range of 130 <C _R / d _w ^ 195, and more preferably in the range of 140 <C _R / d _w ^ 195.

Support The term "alumina" as used herein includes all conceivable structures such as alpha, gamma or theta alumina

Embodiment, the alumina carrier is an alpha alumina carrier.

According to a further preferred embodiment, the alpha-alumina has a purity of at least 75%, preferably a purity of at least 80%, more preferably a purity of at least 85%, more preferably a purity of at least 90%. For example, the alpha alumina has a purity of at least 98%, at least 98.5% or at least 99%. The term alpha-alumina therefore also includes alpha-aluminas containing further constituents, in particular constituents selected from the group consisting of zirconium, alkali metals, alkaline earth metals, silicon, zinc, gallium, hafnium, boron, fluorine, copper, nickel, manganese, iron , Cerium, titanium, chromium and mixtures of two or more thereof.

The alpha-alumina may contain the ingredients in any suitable form, for example as an element or in the form of one or more compounds. If the alpha-alumina contains one or more constituents in the form of a compound, it contains these, for example, as oxide or mixed oxide.

As for the amount of the other ingredients, the total content of the other ingredients is preferably in a range of less than 25% by weight, more preferably less than 20% by weight, more preferably less than 15% by weight, and more preferably less than 10% by weight, based on the total weight of the alumina support and calculated as the sum of those other than aluminum and oxygen

Elements.

For example, if the alumina support contains silicon, it preferably contains it in an amount in the range of up to 10,000 ppm by weight, preferably in the range of 10 ppm by weight to 8,000 ppm by weight, more preferably in an amount of 50% by weight. ppm to 5000 ppm by weight, more preferably in an amount of 200 ppm by weight to 2800 ppm by weight, based on the total weight of the alumina support and calculated as the element. According to a particularly preferred embodiment of the invention is the

An alumina carrier is an alpha alumina carrier, wherein the alpha alumina has a purity of at least 85% and more preferably in an amount of up to 10,000 ppm by weight, preferably in the range of from 10 ppm to 8,000 ppm by weight in an amount of 50 ppm by weight to 5000 ppm by weight, more preferably in an amount of 200 ppm by weight to 2800 ppm by weight, based on the total weight of

Aluminum oxide support and calculated as element contains.

If the alumina support contains, for example, alkali metals, it preferably contains these in a total amount in the range of at most 2500 ppm by weight, more preferably in a total amount of 10 ppm by weight to 1500 ppm by weight, more preferably in a total amount of 50% by weight . ppm to 1000 ppm by weight, based on the

Total weight of alumina support and calculated as element. According to a preferred embodiment, the alumina carrier contains at least one alkali metal, in particular sodium and / or potassium.

Accordingly, the present invention also relates to a shaped catalyst body, as described above and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body prepared or prepared by this method, wherein the alumina carrier contains at least one alkali metal, in particular sodium and / or potassium.

If the alumina carrier contains sodium, it preferably contains it in an amount in the range from 10 ppm by weight to 1500 ppm by weight, more preferably in an amount of from 10 ppm by weight to 800 ppm by weight, more preferably in one Amount of 10 ppm by weight to 700 ppm by weight, more preferably in an amount of 10 ppm by weight to 500 ppm by weight, based on the total weight of the alumina support and calculated as an element, wherein the total amount of all alkali metals, such as described above, preferably in the range of 10 ppm by weight to 2500 ppm by weight.

If the alumina carrier contains potassium, it preferably contains it in an amount of at most 1000 ppm by weight, more preferably in an amount of not more than 500 Ppm by weight, more preferably in an amount of at most 200 ppm by weight,

For example, in the range of 10 ppm by weight to 100 ppm by weight, based on the

Total weight of the alumina support and calculated as element, the

Total amount of all alkali metals, as described above, preferably in the range of 10 ppm by weight to 2500 ppm by weight.

According to a preferred embodiment of the invention contains the

Aluminum oxide carrier sodium in an amount of 10 ppm by weight to 1500 ppm by weight and potassium in an amount of at most 1000 ppm by weight.

According to a further embodiment, the alumina carrier contains at least one alkaline earth metal. If the alumina carrier contains at least one alkaline earth metal, it preferably additionally contains at least one alkali metal, as described above. If the alumina carrier contains at least one alkaline earth metal, it preferably contains a total amount of alkaline earth metals in the range of at most 2500 ppm by weight, for example in the range of 1 to 2500 ppm by weight, more preferably in an amount of 10 to 1200 ppm by weight , more preferably in an amount of 100 to 800 ppm by weight based on the total weight of the alumina carrier and calculated as an element. The term "total amount of alkaline earth metals" as used herein refers to the sum of all alkaline earth metals optionally contained in the alumina support, based on the total weight of the alumina support and calculated as an element in each case according to one embodiment of the invention the alumina support comprises at least one alkaline earth metal selected from If the alumina support contains, for example, calcium, it preferably contains this in an amount in the range of 10 ppm by weight to 1500 ppm by weight, more preferably in an amount of 20 ppm by weight to 1000% by weight . ppm, more preferably in an amount of 30 ppm by weight to 700 ppm by weight, based on the total weight of

Alumina carrier and calculated as element.

If the alumina support contains, for example, magnesium, it preferably contains this in an amount in the range of at most 800 ppm by weight, preferably in an amount of from 1 ppm by weight to 500 ppm by weight, more preferably in an amount of 1% by weight. ppm to 250 ppm by weight, more preferably in an amount of 1 ppm by weight to 100 ppm by weight, based on the total weight of the alumina support and calculated as element. Accordingly, the present invention relates to a shaped catalyst body as described above and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body produced or produced by this method, wherein the alumina carrier magnesium in an amount of at most 800th Ppm by weight, and calcium in an amount of from 10 ppm by weight to 1500 ppm by weight, based in each case on the total weight of the aluminum oxide carrier and calculated as element. More preferably, the alumina support comprises sodium in an amount of 10 ppm by weight to 1500 ppm by weight, potassium in an amount of at most 1000 ppm by weight, magnesium in an amount of at most 800 ppm by weight, and calcium in one Amount of 10 ppm by weight to 1500 ppm by weight, each based on the total weight of the alumina support and calculated as element.

In the context of the invention it is particularly preferred that the alumina support contains zirconium. Contains the alumina carrier zirconium, it preferably contains this in an amount in the range of 1 ppm by weight to 10,000 ppm by weight, more preferably in the range of 10 ppm by weight to 8000 ppm by weight, more preferably in the range of 50 ppm by weight to 6000 ppm by weight, and more preferably in the range of 50 ppm by weight to 5000 ppm by weight, calculated as metal and based on the total weight of

Alumina support.

The alumina carrier of the present invention may further include zinc as

Component included. If the alumina support contains zinc as an ingredient, it contains this in an amount of at most 800 ppm by weight, preferably in an amount of at most 600, more preferably in an amount in the range of 1 ppm by weight to 400 ppm by weight, calculated as an element and based on the total weight of the

Alumina support.

If the alumina support contains further constituents, for example selected from the group consisting of gallium, hafnium, boron, fluorine, copper, nickel, manganese, iron, cerium, titanium and chromium, it preferably contains these in each case in an amount of at most 500% by weight. ppm, calculated in each case as metal and based on the total weight of the alumina support.

The alumina supports used according to the invention preferably contain a BET surface area, determined in accordance with DIN ISO 9277, of 0.1 to 5 m ² / g, more preferably in the range of 0.1 to 2 m ² / g, more preferably in the range of 0, 5 to 1, 5 m ² / g, more preferably in the range of 0.63 to 1, 3 m ² / g, more preferably in the range of 0.65 to 1, 2 m ² / g and particularly preferably in the range of 0 , 7 to 1, 2 m ² / g such as in the range of 0.7 to 1, 1 m ² / g.

Accordingly, the present invention relates to a shaped catalyst body, as described above and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body produced or produced by this method, wherein the alumina support a BET surface, determined according to DIN ISO 9277, in the from 0.1 to 5 m ² / g, more preferably in the range from 0.1 to 2 m ² / g, more preferably in the range of 0.5 to 1.5 m ² / g, more preferably in the range of 0.63 to 1.3 m ² / g, more preferably in the range of 0.65 to 1.2 m ² / g and more preferably in the range of 0.7 to 1.2 m ² / g. Furthermore, the aluminum oxide supports according to the invention preferably have pores

Diameters in the range of 0.1 to 100 μηη, wherein the pore distribution can be monomodal or polymodal, for example bimodal. Preferably, the

Aluminum oxide carrier on a bimodal pore distribution. Accordingly, the present invention also relates to a shaped catalyst body as described above, and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body produced or producible by this method, wherein the alumina carrier, preferably the alpha alumina carrier, having a bimodal pore distribution.

More preferably, the alumina supports have a bimodal pore distribution with peak maxima in the range of 0.1 μηη to 10 μηη and 15 μηη to 100 μηη, preferably in the range of 0.1 μηη to 5 μηη and 17 μηη to 90 μηη, more preferably in the range of 0.1 μηη to 3 μηη and 20 μηη to 80 μηη, more preferably in the range of 0.1 μηη to 2.0 μηη and 20 μηη to 70 μηη on. The pore diameters are determined by Hg porosimetry (DIN 66133).

Accordingly, the present invention also relates to a shaped catalyst body as described above, and a method for producing a shaped catalyst body as described above, and a shaped catalyst body produced or producible by this method, wherein the alumina carrier has a bimodal pore distribution, preferably a bimodal pore distribution at least containing pores With

Pore diameters in the range of 0.1 μηη to 10 μηη and pores with pore diameters in the range of 15 μηη to 100 μηη, determined by Hg porosimetry according to DIN 66133. The water absorption of the alumina carrier is preferably in the range of 0.35 ml / g to 0 , 65 ml / g, preferably in the range of 0.42 ml / g to 0.52 ml / g, determined by a vacuum cold water absorption.

In general, such alumina carriers are prepared by mixing the

Alumina support material, in particular the alumina, with the addition of at least one binder or at least one extrusion aid or at least one pore-forming agent or a water-containing composition or a mixture of two or more thereof and then deforming the mixture to obtain a shaped body produced.

Suitable pore formers are, for example, cellulose and cellulose derivatives, such as, for example, carboxymethyl cellulose, polyolefins, such as polyethylenes and polypropylenes. The Pore formers are usually substantially completely, preferably completely, removed by subsequent calcination of the alumina support.

Suitable binders are, for example, alumina gels with nitric acid or acetic acid, cellulose, methyl, ethylcellulose, carboxyethylcellulose, methyl or ethyl stearates, waxes, polyolefin oxides. Suitable Verstrangungshilfsmittel are described for example in EP 0496 386 B2, page 3 [0019-0021].

Usually, the molded article obtained as described above is optionally dried following the molding and calcined to obtain the alumina support according to (a). The calcination is usually carried out at temperatures in the range of 1200 ° C to 1600 ° C. Often, the alumina carrier is additionally washed after calcining to remove soluble components.

Alumina carriers are, for example, commercially available from NorPro Co.

silver

In addition to rhenium, the catalyst molding, as stated above, comprises silver as the active metal deposited on the alumina support. As for the amount of silver, the shaped catalyst body preferably comprises silver in an amount of 5 to 30% by weight, more preferably in an amount of 5 to 25% by weight, and particularly preferably in an amount of 10 to 20% by weight. -%, calculated as an element and related to the

Total weight of the catalyst molding. Accordingly, the present invention relates to a shaped catalyst body as described above, wherein the shaped catalyst body silver in an amount of 5 to 30% by weight, based on the total weight of the shaped catalyst body and calculated as an element having. Likewise, the present invention relates to a method for producing a

A shaped catalyst body as described above, and a shaped catalyst body produced or producible by this method, the method comprising (a) providing an alumina support having the geometry of a hollow cylinder,

(b) depositing silver and rhenium on the alumina support, wherein rhenium is in an amount C _R / wt ppm, based on the wall thickness of the hollow cylinder dw / mm, and calculated as an element in the range of 120 <C _R / d _w ^ 200 is applied to the support, and wherein silver in an amount of 5 to 30 wt .-%, based on the total weight of the shaped catalyst body and calculated as an element, is applied. The application of silver on the catalyst molding is preferably carried out by

Contacting the alumina support with at least one mixture G1 comprising at least one silver compound. As far as the contacting of G1 with the catalyst support is concerned, all methods by which the mixture can be applied in a suitable manner are generally suitable. The at least one mixture G1, which comprises at least one silver compound, is preferably applied to the carrier by impregnation or spraying or mixing processes. By way of example, mention may be made of the preparation processes for silver catalysts, as described in DE-A 2300512, DE-A 2521906, EP-A 14457, EP-A 85237, EP-A 384312, DE-A 2454972, DE-A 3321895, EP-A 229465 DE-A 3150205, EP-A 172565 and EP-A 357293 are disclosed.

Particularly preferred is the application of silver by vacuum impregnation at room temperature. In the case of vacuum impregnation, the catalyst support, as described above, is preferably first treated at a pressure in the range of at most 500 mbar, more preferably at a pressure of at most 250 mbar and particularly preferably at a pressure of not more than 30 mbar. This is particularly preferably carried out at a temperature in the range of 1 ° C to 80 ° C, more preferably at a temperature in the range of 3 ° C to 50 ° C, more preferably at a temperature in the range of 5 ° C to 30 ° C and particularly preferably at room temperature. The vacuum treatment is preferably carried out for a time of at least 1 min, preferably of at least 5 min, more preferably for a time in the range of 5 min to 120 min, in particular in the range of 10 min to 45 min, particularly preferably in the range of 10 min up to 30 min.

After the vacuum treatment at least mixture G1 with the

Catalyst carrier brought into contact. Preferably, mixture G1 is dripped or sprayed on, preferably sprayed on. The application is preferably carried out by means of a nozzle.

Mixture G1 contains silver, preferably in the form of at least one silver compound.

The silver compound is preferably dissolved, in particular dissolved in water, applied. Accordingly, G1 furthermore preferably contains at least one solvent, preferably water. To obtain the silver compound in soluble form, the

Silver compound, such as silver (I) oxide or silver (I) oxalate, further suitably a complexing agent, such as at least one amine, especially ethanolamine, EDTA, 1, 3 or 1, 2-propanediamine, ethylenediamine and or alkali metal oxalate , which can also act as a reducing agent at the same time.

Thus, according to a preferred embodiment, G1 contains at least one

Complexing agent, in particular ethanolamine, EDTA, 1, 3 or 1, 2-propanediamine, ethylenediamine and / or alkali metal oxalate. If G1 contains at least one complexing agent, G1 contains at least part of the silver in the form of a silver complex compound. Most preferably, G1 contains at least a portion of the silver as a cationic silver oxalatoethylenediamine compound. G1 particularly preferably comprises water, silver oxalatoethylenediamine complexes and, if appropriate, excess ethylenediamine.

As for the concentration of G1 on the silver-containing compound, it is preferably in the range of 25 to 35%, more preferably in the range of 26 to 32%, and more preferably in the range of 27 to 30%.

As stated above, in step (b), silver calculated as elemental Ag is in an amount of 5 to 30% by weight, more preferably in an amount of 5 to 25% by weight, and most preferably in an amount of 10 to 20 wt .-%, calculated as the element and based on the total weight of the shaped catalyst body, on the

Aluminum oxide carrier applied.

The application in (b) can also take place in more than one step, for example in 2, 3 or 4 steps. Between the individual steps can the

Alumina supports are each optionally optionally dried and / or calcined. If the application according to (b) is carried out in more than one step, then the total amount of silver applied after all steps on the alumina support is likewise in the range from 5 to 30% by weight, more preferably in the range from 5 to 25% by weight. , and more preferably in an amount of 10 to 20 wt .-%, calculated as an element and based on the total weight of the shaped catalyst body, as described above.

After application of the silver, at least one post-treatment step, for example a drying step, e.g. connect one, two or more drying steps. The drying is usually carried out at temperatures in the range of 2 to 200 ° C. The post-treatment step is preferably drying by means of vacuum treatment, as described above. This evacuation is preferably carried out at a pressure in the range of at most 500 mbar, more preferably at a pressure of at most 250 mbar and particularly preferably at a pressure of a maximum of 30 mbar. Preferably, the vacuum treatment is carried out at a temperature in the range of 2 to 50 ° C, more preferably at a temperature in the range of 5 to 30 ° C and more preferably at room temperature. The vacuum treatment is carried out for a time of at least 1 min, preferably of at least 5 min, more preferably for a time in the range of 5 min to 120 min, in particular in the range of 10 min to 45 min, particularly preferably in the range of 10 min to 20 min. After application of the silver and optionally the at least one

Drying step preferably includes at least one calcination step.

rhenium The shaped catalyst body according to the invention contains at least rhenium as promoter in addition to silver.

Rhenium is preferably applied to the support by impregnation or spraying or blending as described above for silver.

As regards the rhenium application time, this may be done following the application of silver and / or subsequent to the at least one post-treatment step, if any. Alternatively, it is possible that

Rhenium together with the silver compound or before applying the

Apply silver compound on the support. When the rhenium is applied to the alumina support before silver, at least one post-treatment step, for example a drying step, e.g. one, two or more drying steps, and / or for example at least one calcination step, connect. Rhenium is particularly preferably applied in step (b) simultaneously with silver on the alumina support. In this case, the rhenium can be applied in parallel to the application of silver, preferably in the form of at least one rhenium compound, in a mixture G2 on the support. In addition to the at least one silver compound, G1 preferably also contains rhenium and / or at least one rhenium compound.

The rhenium is used in particular as a compound, for example as a halide,

Oxyhalide, oxide or applied as acid. Furthermore, rhenium can be used in the form of salts of the heteropolyacids of rhenium, for example as rhenate or perrhenate in the preparation process according to the invention.

Accordingly, the present invention also relates to a process as described above, and a catalyst, preparable or prepared by this process, comprising

(a) providing an alumina support having the geometry of a hollow cylinder,

(b) applying silver and rhenium on the alumina support

Contacting the alumina support with at least one mixture G1 containing at least one silver compound and at least one

Rhenium compound, wherein the contacting preferably means

Vacuum impregnation is carried out, and wherein rhenium in an amount C _R /Gew.-ppm, based on the wall thickness of the hollow cylinder d _w / mm, and calculated as an element which is in the range of 120 <C _R / d _w ^ 200, on the Carrier is applied and wherein silver in an amount of 5 to 30 wt .-%, based on the

Total weight of the catalyst mold body and calculated as an element is applied.

Preferably, in step b) rhenium is applied as a compound on the alumina support, wherein the compound is selected from the group consisting of Ammonium perrhenate, rhenium (III) chloride, rhenium (V) chloride, rhenium (V) fluoride, rhenium (VI) oxide, and rhenium (VII) oxide. In the context of the invention, particular preference is given to using rhenium as ammonium perrhenate on the alumina support. Further promoters

In addition to rhenium, the shaped catalyst body may comprise at least one further promoter. Particularly preferably, the shaped catalyst body contains at least one further promoter.

Thus, within the scope of the invention, for example, embodiments are encompassed in which the shaped catalyst body comprises rhenium, five different promoters, four different promoters, three different promoters, two different promoters or a further promoter applied to the alumina support.

In particular, this is at least one further promoter selected from elements of groups IA, VIB, VII B and VIA of the Periodic Table of the Elements, more preferably selected from the group consisting of tungsten, lithium, sulfur, cesium, chromium, manganese, molybdenum and potassium. Accordingly, the present invention relates to a shaped catalyst body, as described above, and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body prepared or prepared by this method, wherein the shaped catalyst body at least one further promoter selected from the group consisting of elements of Group IA, VIB, VIIB and VIA, preferably selected from the group consisting of tungsten, cesium, lithium and sulfur.

According to a particularly preferred embodiment, in addition to rhenium, the catalyst contains at least cesium, lithium, tungsten and sulfur as promoters.

If the catalyst molding contains at least one further promoter, it preferably contains a total amount of these further promoters in an amount of from 10 ppm by weight to 2000 ppm by weight, preferably in an amount of from 10 to 1700 ppm, more preferably in each case in an amount of 50 ppm by weight to 1500 ppm by weight and more preferably in each case in an amount of 80 ppm by weight to 1200 ppm by weight, based on the total weight of the catalyst molding and calculated as the sum of the elements.

If the catalyst molding contains tungsten as a promoter, as described above, the tungsten is preferably applied to the support as a tungsten compound. Here, in principle, any suitable tungsten compound is usable. For example, tungsten is applied in the form of tungstate or tungstic acid. The shaped catalyst body preferably contains tungsten as promoter in an amount of up to 800 ppm by weight, preferably in an amount in the range of 5 to 500 ppm by weight, more preferably in one Amount in the range of 100 to 300 ppm by weight, based on the total weight of the catalyst mold body and calculated as element.

If the catalyst molding contains lithium as a promoter, as described above, the lithium is preferably applied to the support as a lithium compound. Here is in

Principle any suitable lithium compound usable. Preferably, lithium is applied in the form of lithium nitrate. If the catalyst molding contains lithium as a promoter, it preferably contains lithium in an amount of up to 700 ppm by weight, preferably in an amount of up to 10 ppm by weight to 500 ppm by weight, more preferably in an amount of Range from 80 ppm by weight to 250 ppm by weight, based on the total weight of the shaped catalyst body and calculated as element.

If the catalyst molding contains cesium as a promoter, as described above, the cesium is preferably applied to the support as a cesium compound. Here, in principle, any suitable cesium compound is usable. Preferably, cesium is applied in the form of cesium hydroxide. If the catalyst tablet contains cesium as a promoter, it preferably contains cesium in an amount of up to 1500 ppm by weight, preferably in an amount in the range of up to 100 ppm by weight to 800 ppm by weight, more preferably in an amount in the range of 200 ppm by weight to 600 ppm by weight, based on the total weight of the shaped catalyst body and calculated as element.

If the catalyst molding contains sulfur as a promoter, as described above, the sulfur is preferably applied to the support as a sulfur compound. Here, in principle, any suitable sulfur compound is usable. Preferably, sulfur is applied in the form of ammonium sulfate. If the catalyst molding contains sulfur as a promoter, it preferably contains sulfur in an amount of 0 to 50 ppm by weight, more preferably in an amount in the range of 1 ppm by weight to 25 ppm by weight, based on the total weight of the catalyst molding and calculated as an element. Accordingly, the present invention relates to a shaped catalyst body, as described above, and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body produced or prepared by this method, wherein the shaped catalyst body tungsten in an amount in the range of 5 ppm by weight 500 ppm by weight, cesium in an amount ranging from 100 ppm by weight to 800 ppm by weight, lithium in an amount ranging from 10 ppm by weight to 500 ppm by weight, and sulfur in an amount in the range from 0 to 50 ppm by weight, based on the

Total weight of the catalyst molding and calculated as element contains.

If the catalyst molding contains at least one further promoter, then this at least one further promoter is preferably applied to the support in the form of compounds, for example in the form of complexes or in the form of salts, for example in the form of halides, in the process according to the invention for preparing the catalyst, for example in the form of fluorides, bromides or chlorides, or in Form of carboxylates, nitrates, sulphates or sulphides, phosphates, cyanides,

Hydroxides, carbonates or as salts of heteropolyacids.

Preferably, the at least one further promoter, more preferably the at least one further promoter compound, is dissolved before application in a suitable solution, preferably in water. The alumina support is then preferably contacted (impregnated) with the resulting solution comprising one or more of the further promoters. Should several more promoters be added, they may be applied in one single step or in several steps either together or separately on the carrier. As regards the solution comprising one or more of the further promoters, it may be prepared in any suitable manner.

For example, the promoters can each be separately dissolved in each case in a solution and the resulting solutions, each containing a promoter, are then used for impregnation. It is also possible that two or more of the other promoters are dissolved together in a solution, and the resulting solution is then used for impregnation. In addition, it is possible that the solutions obtained, containing at least one promoter, are combined prior to impregnation and the solution obtained, containing all the promoters, are applied to the support.

As regards the time of application of the at least one further promoter, this may take place following the application of silver and / or rhenium and / or following at least one optionally carried out

Post-treatment step done. Alternatively, it is possible to apply the at least one further promoter together with the silver compound and / or the rhenium compound or before the silver compound and / or the rhenium compound on the support.

Particularly preferably, the at least one further promoter in step (b) is applied simultaneously with silver and rhenium on the alumina support. In this case, the at least one further promoter can be applied in parallel to the application of silver and rhenium, in a separate mixture G3 on the carrier.

The at least one further promoter is preferably applied to the aluminum oxide support as a constituent of the mixture G1, which preferably also contains rhenium and / or at least one rhenium compound in addition to the at least one silver compound. The at least one further promoter is therefore preferably applied to the alumina support together with rhenium and silver. Particularly preferred are all contained in the catalyst form body further

Promoters along with rhenium and silver on the alumina support

applied.

(a) providing an alumina support having the geometry of a hollow cylinder,

(b) applying silver, rhenium and at least one further promoter on the alumina support by contacting the alumina support with at least one mixture G1 containing at least one silver compound and at least one rhenium compound, and at least one further promoter in the form of at least one compound, the contacting preferably by means of Vacuum impregnation is carried out, and wherein rhenium in an amount C _R /Gew.-ppm, based on the wall thickness of the hollow cylinder d _w / mm, and calculated as an element which is in the range of 120 <C _R / d _w ^ 200, on the Carrier is applied, and wherein silver in an amount of 5 to 30 wt .-%, based on the

Total weight of the catalyst molding and calculated as an element is applied.

For example, if at least cesium, tungsten, lithium, sulfur are used as further promoters, according to a particularly preferred embodiment, at least one solution containing cesium (in the form of at least one compound) and tungsten (in the form of at least one compound), another solution containing lithium (in the form of at least one compound) and sulfur (in the form of at least one

Compound), and another solution containing rhenium (in the form of at least one compound).

According to one embodiment, the solutions are in separate

Impregnation steps applied to the carrier. Particularly preferably, the solutions are combined with a solution containing at least one silver compound to obtain the mixture G1. Thus, in addition to the at least one silver compound, G1 particularly preferably comprises at least one rhenium compound, at least one cesium compound, at least one lithium compound, at least one

Tungsten compound and optionally further promoters, each in the form of at least one compound.

Accordingly, the present invention relates to a shaped catalyst body as described above, and a method for producing a shaped catalyst body as described above, and a shaped catalyst body prepared or prepared by this method, wherein the catalyst additionally at least one further promoter selected from elements of group IA, VIB , VIIB and VIA of the Periodic Table of the Elements, preferably selected from the group consisting of tungsten, lithium, Sulfur, cesium, chromium, manganese, molybdenum and potassium, wherein the at least one further promoter preferably in step (b) on the alumina support by contacting the alumina support, preferably by vacuum impregnation, with the mixture G1, which additionally comprises the at least one promoter, is applied.

According to a particularly preferred embodiment, the catalyst contains tungsten in an amount of 100 ppm by weight to 500 ppm by weight, cesium in an amount of 100 ppm by weight to 800 ppm, lithium in an amount of 10 ppm by weight 500 ppm by weight and sulfur in an amount of 0 to 50 ppm by weight.

Accordingly, the present invention relates to a shaped catalyst body, as described above, and a method for producing a shaped catalyst body, as described above, and a shaped catalyst body produced or produced by this method, wherein the shaped catalyst body tungsten in an amount of 100 ppm by weight to 500 wt . ppm, cesium in an amount of 100 ppm by weight to 800 ppm, lithium in an amount of 10 ppm by weight to 500 ppm by weight and sulfur in an amount of 0 to 50 ppm by weight. Step (c)

After step (b), at least one post-treatment step, for example a drying step, e.g. one, two or more drying steps. The drying is usually carried out at temperatures in the range of 2 to 200 ° C. For example, the post-treatment step is drying by vacuum treatment as described above. This evacuation is preferably carried out at a pressure in the range of at most 500 mbar, more preferably at a pressure of at most 250 mbar and particularly preferably at a pressure of a maximum of 30 mbar. Preferably, the vacuum treatment is carried out at a temperature in the range of 2 ° C to 50 ° C, more preferably at a temperature in the range of 5 ° C to 30 ° C, and most preferably at room temperature. The vacuum treatment is carried out for a time of at least 1 min, preferably of at least 5 min, more preferably for a time in the range of 5 min to 120 min, in particular in the range of 10 min to 45 min, particularly preferably in the range of 10 min to 20 min.

Preferably, the optionally dried alumina support is calcined according to (b). Accordingly, the present invention also relates to a process as described above and a catalyst preparable or prepared by this process, comprising (c) drying and / or calcining the alumina support according to (b) to obtain the catalyst molding.

If calcination in step (c), this calcination is preferably carried out at temperatures in the range of 150 to 750 ° C, preferably in the range of 200 to 500 ° C and especially preferably in the range of 220 to 350 ° C, wherein the calcination time is generally at least 5 minutes or more, for example in the range of 5 minutes to 24 hours or in the range of 10 minutes to 12 hours. More preferably, the calcination time is in the range of 5 minutes to 3 hours. The calcination can be carried out at a constant temperature, further embodiments are included, in which the temperature is changed continuously or discontinuously during the Calcinierungsdauer. The calcination can take place under any suitable gas atmosphere,

For example, in an inert gas or a mixture of an inert gas and 10 ppm to 21 vol .-% oxygen. As an inert gas, for example, nitrogen, argon, carbon dioxide, helium and a combination of at least two of the aforementioned inert gases may be mentioned. When the calcination is carried out in an inert gas, nitrogen is particularly preferred. According to an alternative preferred embodiment, air and / or lean air is used.

Furthermore, the calcination is preferably in a muffle furnace, convection oven, in one

Rotary kiln and / or a belt calciner carried out.

Process for the preparation of ethylene oxide

The shaped catalyst bodies according to the invention or the shaped catalyst bodies produced or producible by a process according to the invention are suitable

in particular as catalysts for the production of ethylene oxide from ethene, comprising an oxidation of ethene. High selectivities, in particular advantageous starting selectivities, and good activities are achieved.

The present invention therefore also relates, according to a further aspect, to a process for the production of ethylene oxide from ethene, comprising an oxidation of ethene in the presence of a catalyst tablet for the production of ethylene oxide, as described above.

Moreover, the present invention also relates to the use of a

Catalyst molding, as described above, for the production of ethylene oxide by gas phase oxidation of ethene.

According to the invention, the epoxidation can take place according to all methods known to the person skilled in the art. Any of the reactors which can be used in the ethylene oxide preparation processes of the prior art can be used here, for example externally cooled tube bundle reactors (compare Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Vol. A-10, pages 1 17-135, 123-125 VCH-Verlagsgesellschaft, Weinheim 1987) or reactors with loose catalyst bed and cooling tubes, for example, those in DE-A 3414717, EP 0082609 and EP-A 0339748 described reactors. Preferably, the epoxidation takes place in at least one tubular reactor, preferably in a tube bundle reactor. For the production of ethylene oxide from ethene and oxygen, under conventional reaction conditions, as described, for example, in DE-A 2521906, EP-A 0 014 457, DE-A 2300512, EP-A 0 172 565, DE-A 2454972, EP-A 0 357 293, EP-A 0 266 015, EP-A 0 085 237, EP-A 0 082 609 and EP-A 0 339 748. The reaction gas containing ethene and molecular oxygen may additionally contain inert gases such as nitrogen or gases which are inert under the reaction conditions, such as water vapor, methane and optionally

Reaction moderators, for example, halogenated hydrocarbons such as ethyl chloride, vinyl chloride or 1, 2-dichloroethane are added. Conveniently, the oxygen content of the reaction gas is in a range in which no explosive gas mixtures are present. A suitable composition of the reaction gas for the production of ethylene oxide may, for. B. from an amount of ethene in the range of 10 to 80 vol .-%, preferably from 20 to 60 vol .-%, more preferably from 25 to 50 vol .-%, and particularly preferably in the range of 30 to 40 vol. %, based on the total volume of the reaction gas. The oxygen content of the reaction gas is expediently in the range of at most 10 vol .-%, preferably of at most 9 vol .-%, more preferably of at most 8 vol .-%, and most preferably of at most 7 vol .-%, based on the total volume of the reaction gas.

Preferably, the reaction gas contains a chlorine-containing reaction moderator such as

Ethyl chloride, vinyl chloride or dichloroethane in an amount of 0 to 15 ppm by weight, preferably in an amount of 0.1 to 8 ppm by weight. The remainder of the reaction gas usually consists of hydrocarbons, such as methane, or else

Inert gases such as nitrogen. In addition, other substances such as water vapor, carbon dioxide or noble gases may be contained in the reaction gas.

The components of the reaction mixture described above may optionally each have small amounts of impurities. For example, ethene may be used in any degree of purity suitable for the gas phase oxidation of the present invention. Suitable levels of purity include, but are not limited to, polymer grade ethylene, which typically has a purity of at least 99%, and chemical grade ethylene which has low purity, typically less than 95%. The impurities typically consist mainly of ethane, propane and / or propene.

The reaction or oxidation of ethene to ethylene oxide is usually carried out at elevated temperature. Preference is given to temperatures in the range of 150 to 350 ° C, more preferably in the range of 180 to 300 ° C, more preferably temperatures in

Range of 190 ° C to 280 ° C and more preferably temperatures in the range of 200 ° C to 280 ° C. Accordingly, the present invention also relates to a method, such as described above, wherein the oxidation at a temperature in the range of 180-300 ° C, preferably in the range of 200 to 280 ° C, takes place.

In the reaction according to the invention (oxidation), preference is given to working at pressures in the range from 5 bar to 30 bar. More preferably, the oxidation is carried out at a pressure in the range of 5 bar to 25 bar, preferably at a pressure in the range of 10 bar to 20 bar and in particular in the range of 14 bar to 20 bar. Accordingly, the present invention also relates to a process as described above, wherein the oxidation takes place at a pressure in the range of 14 bar to 20 bar.

Preferably, the oxidation is carried out in a continuous process. If the reaction is carried out continuously, a GHSV (gas hourly space velocity), depending on the nature of the selected reactor, for example from the

Size / average area of the reactor, the shape and size of the catalyst used, which is preferably in the range of 800 to 10,000 / h, preferably in the range of 2000 to 6000 / h, more preferably in the range of 2500 to 5000 / h, wherein the

Refer to the volume of the catalyst.

Advantageously, the production of ethylene oxide from ethene and oxygen can be carried out in a cyclic process. The reaction mixture is circulated through the reactor, where after each pass the newly formed ethylene oxide and the by-products formed in the reaction are removed from the product gas stream, which is fed back to the reactor after addition of the required amounts of ethene, oxygen and Reaktionsmoderatoren becomes. The separation of the ethylene oxide from the product gas stream and its work-up can be carried out according to the customary processes of the prior art (compare Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A-10, pp. 1 17-135, 123-125, VCH Verlagsgesellschaft, Weinheim 1987). In the following, particularly preferred embodiments of the invention are mentioned:

1 . Catalyst form body for producing ethylene oxide, comprising at least silver and rhenium supported on an alumina support, wherein the alumina support has the geometry of a hollow cylinder, and wherein the catalyst form body has a rhenium content C _R and C _R /Gew.-ppm, based on the wall thickness of Hollow cylinder dw / mm, and calculated as element, is in the range of 120 <C _R / d _w ^ 200.

Catalyst form body according to embodiment 2, wherein the hollow cylinder has a length L in the range 5 to 10 mm, an outer diameter d _A in the range of 5 to 10 mm and a ratio of outer diameter d _A / mm to wall thickness dw / mm in the range of 2.5 to 4.5. Catalyst form body according to embodiment 2, wherein the hollow cylinder has a length L in the range 6 to 9.5 mm. Catalyst form body according to one of embodiments 1 to 3, wherein the shaped catalyst body silver in an amount of 5 to 30 wt .-%, based on the total weight of the shaped catalyst body and calculated as an element. Catalyst form body according to any one of embodiments 1 to 4, wherein the alumina carrier, preferably the alpha alumina carrier, has a bimodal pore distribution. Catalyst form body according to any one of embodiments 1 to 5, wherein the alumina support has a BET surface area in the range of 0.7 to 1.2 m ² / g. The shaped catalyst body according to any one of Embodiments 1 to 6, wherein the alumina carrier contains calcium in an amount ranging from 10 ppm by weight to 1500 ppm by weight based on the total weight of the carrier and calculated as an element. Catalyst molding according to one of embodiments 1 to 7, wherein the alumina support magnesium in an amount in the range of at most 800 ppm by weight, preferably in an amount of 1 ppm by weight to 500 ppm by weight, based on the total weight of the carrier and calculated as an element containing. Catalyst form body according to any of embodiments 1 to 8, wherein the alumina support contains potassium in an amount in the range of at most 1000 ppm by weight, based on the total weight of the support and calculated as element. The shaped catalyst body according to any one of Embodiments 1 to 9, wherein the alumina carrier contains sodium in an amount ranging from 10 ppm by weight to 1500 ppm by weight based on the total weight of the carrier and calculated as an element. The shaped catalyst body according to any one of Embodiments 1 to 10, wherein the alumina carrier comprises silicon in an amount ranging from 50 ppm by weight to 10,000 ppm by weight, more preferably from 100 ppm by weight to

5000 ppm by weight, more preferably in an amount of 1000 ppm by weight

2800 ppm by weight, based on the total weight of the carrier and calculated as element. Catalyst molding according to one of embodiments 1 to 1 1, wherein the alumina support contains zirconium in an amount in the range of 1 ppm by weight to 10,000 ppm by weight, based on the total weight of the support and calculated as element.

Catalyst molding according to one of embodiments 1 to 12, wherein the catalyst comprises at least one promoter selected from the group consisting of elements of group IA, VIB, VIIB and VIA, preferably selected from the group consisting of tungsten, cesium, lithium and sulfur.

A shaped catalyst body according to any of embodiments 1 to 13, wherein the shaped catalyst body comprises tungsten in an amount ranging from 5 ppm by weight to 500 ppm by weight, cesium in an amount ranging from 100 ppm by weight to 800 ppm by weight, Lithium in an amount in the range of 10 ppm by weight to 500 ppm by weight, and sulfur in an amount in the range of 0 to 50 ppm by weight, calculated as an element and based on the total weight of the catalyst molding.

A process for preparing a shaped catalyst body comprising silver and rhenium supported on an alumina support comprising

(a) providing an alumina support having the geometry of a

Hollow cylinder has,

(b) applying silver and rhenium on the alumina support wherein rhenium in an amount C _R /Gew.-ppm, based on the wall thickness of the hollow cylinder d _w / mm, and calculated as the element, in the range of 120 _<R C / d _w ^ 200, is applied to the alumina support.

The method of embodiment 15, wherein the method further comprises

(c) calcining the alumina support obtained according to (b),

Process according to embodiment 15 or 16, wherein in (b) silver in an amount of 5 to 30 wt .-%, based on the total weight of

Catalyst form body and calculated as an element is applied.

Catalyst molding, preparable by a method according to one of

Embodiments 15 to 17.

Process for the preparation of ethylene oxide by gas phase oxidation of ethene with oxygen in the presence of a shaped catalyst body according to one of

Embodiments 1 to 14 and 18. 20. Use of a shaped catalyst body according to one of embodiments 1 to 14 and 18 as a catalyst for the preparation of ethylene oxide by

Gas phase oxidation of ethene with oxygen.

The present invention is further illustrated by the following examples.

Examples

1. General procedure for the catalyst preparation according to the invention

1.1 Used alumina carriers

Bimodal alpha-alumina supports with hollow ring geometry were used. The properties of the alpha alumina supports are summarized in Table 1 below:

Table 1: Carriers used

Preparation of the silver complex solution It was submitted to 1, 5 L of water and 550 g of silver nitrate added with stirring and completely dissolved therein. The solution was heated to 40.degree. 402.62 g of potassium hydroxide solution (47.8%) were mixed with 1.29 L of water. Subsequently, 216.31 g of oxalic acid were added and completely dissolved, and the solution was heated to 40 ° C. The potassium oxalate solution was then added within about 45 min (volume flow = about 33 ml / min) to the silver nitrate solution (40 ° C) using a metering pump. After complete addition, the resulting solution was allowed to stir for 1 h at 40 ° C. The precipitated silver oxalate was filtered off and the resulting filter cake was washed with 1 L portions of water (about 10 L) until it was free of potassium or nitrate (determined by means of conductivity measurement of the

Washing solution, potassium- or nitrate-free in the present case means a conductivity <40μ5 / ηη "ΐ.) The water was removed as completely as possible from the filter cake and the residual moisture content of the filter cake was determined to be 620 g of silver oxalate with a water content of 20.80%. receive.

306 g of ethylenediamine were cooled with an ice bath to about 10 ° C and 245 g of water in small portions. After completion of the addition of water, 484.7 g of the obtained (still moist) Silberoxalates within about 30 minutes in small portions. The mixture was stirred at room temperature overnight and the residue was then removed by centrifugation. From the remaining clear solution, the Ag content was determined by refractometry and the density using a 10 mL graduated cylinder.

The resulting solution contained 29.35% by weight of silver, calculated as element, and had a density of 1.536 g / mL. Preparation of the solution containing silver and promoters

87.61 g of the silver complex solution were initially charged. 1.1 g of a solution of lithium and sulfur (2.85% by weight of lithium and 0.21% by weight) were added thereto.

Sulfur) _, 1.66 g of a solution of tungsten and cesium (2% by weight tungsten and 3.5% by weight cesium) and ammonium perrhenate were added and the solution was stirred for 5 minutes.

The amount of ammonium perrhenate can be found in the respective examples 1 to 12. Applying the solution on the support

140 g of the respective carrier according to 1.1 (see Table 1) were in a

Submitted rotary evaporator and evacuated at 10 mbar. The carrier was pre-evacuated for about 10 min. The solution obtained under 1 .4 was dropped onto the support within 15 minutes, and then the impregnated support was allowed to rotate for a further 15 minutes in vacuo. Thereafter, the support was left for 1 h at room temperature and atmospheric pressure in the apparatus and mixed gently every 15 min.

Calcination of the impregnated carrier

The impregnated support was treated for 12 minutes at 283 ° C under 8.3 m ^{3 of} air per hour in a convection oven (HORO, type 129 ALV-SP, Fabr.Nr.:53270).

epoxidation

The epoxidation was carried out in a test reactor consisting of a vertical reaction tube made of stainless steel with an inner diameter of 6 mm and a length of 2200 mm. The jacketed

Reaction tube was heated with hot oil of temperature T flowing through the jacket. With a very good approximation, the temperature of the oil corresponds to the temperature in the reaction tube and thus the reaction temperature. The

Reaction tube was from bottom to top at a height of 212 mm with inert steatite spheres (1, 0-1, 6 mm), above at an altitude of 1100 mm with 38.2 g of catalyst chippings, particle size 0.5-0.9 mm and above it at a height of 707 mm filled with inert steatite balls (1, 0-1, 6 mm). The inlet gas entered the reactor from above and at the bottom, after passing through the catalyst bed again.

The input gas consisted of 35 vol.% Ethene, 7 vol.% Oxygen, 1 vol.% C0 ₂ (EC (ethylene chloride) moderation). At the beginning, 2.5 ppm EC was used for start-up. Depending on the catalyst and performance, the EC concentration was increased every 24 hours to a maximum of 7 ppm. The remainder of the input gas was methane. The experiments were carried out at a pressure of 15 bar and a gas load (GHSV) of 4750 / h and a space-time yield of 250 kg EO / (m ³ (Kat) xh).

The reaction temperature was controlled according to the specified ethylene oxide exhaust gas concentration of 2.7%. To optimize the catalyst in terms of selectivity and conversion were between 2.2 and 7.0 ppm

Ethylene chloride added as a moderator to the input gas.

The gas leaving the reactor was analyzed by online MS. The selectivity was determined from the analysis results. Catalysts prepared Example 1 (not according to the invention)

140 g of the carrier A were reacted according to general instructions 1 .2 - 1 .5 to the corresponding catalyst. The solution according to general procedure 1.3 contained 0.535 g of a 3.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The prepared catalyst contains 16.7% by weight of silver, tungsten in an amount of 200 ppm by weight, cesium in an amount of 460 ppm by weight, lithium in an amount of 190 ppm by weight, and sulfur in an amount of 14 ppm by weight.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 2 (not according to the invention)

140 g of the carrier A were reacted according to general instructions for the corresponding catalyst. The solution according to general procedure 1.3 contained 1, 579 g of a 2.1% aqueous rhenium solution prepared by dissolving

Ammonium perrhenate in water.

The prepared catalyst contains 16.5% by weight of silver, tungsten in an amount of 200 ppm by weight, cesium in an amount of 460 ppm by weight, lithium in an amount of 190 ppm by weight, and sulfur in an amount of 14 ppm by weight.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 3 (not according to the invention)

140 g of the carrier A were reacted according to general instructions 1 .2 - 1 .5 to the corresponding catalyst. The solution according to item 1.3 contained 1.659 g of a 3.1% aqueous rhenium solution prepared by dissolving

Ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 4

140 g of the carrier A were reacted according to general instructions 1 .2 - 1 .5 to the corresponding catalyst. The solution according to general procedure 1.3 contained 2.141 g of a 3.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 5

140 g of the carrier A were reacted according to general instructions 1 .2 - 1 .5 to the corresponding catalyst. The solution according to general procedure 1.3 contained 2.676 g of a 3.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1 .6. The result is shown in Table 2. Example 6

180 g of the carrier B were reacted according to general rule 1 .2 - 1 .5 to the corresponding catalyst. The solution of General Procedure 1.3 contained 1.63 g of a 4.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The prepared catalyst contains 16.4 wt% silver, tungsten in an amount of 200 wt ppm, cesium in an amount of 420 wt ppm, lithium in an amount of 190 wt ppm, and sulfur in an amount of 14 ppm by weight.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 7 (not according to the invention)

140 g of the carrier B were reacted according to general instructions 1 .2 - 1 .5 to the corresponding catalyst. The solution according to general procedure 1.3 contained 1, 438 g of a 4.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The produced catalyst contains 16.7% by weight of silver, tungsten in an amount of 200 ppm by weight, cesium in an amount of 420 ppm by weight, lithium in an amount of 190 ppm by weight and sulfur in an amount of 14 ppm by weight.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 8

100 g of the carrier C were converted into the corresponding catalyst according to general instructions 1.2-1.5. The solution according to general procedure 1.3 contained 1, 185 g of a 3.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The prepared catalyst contains 15.5% by weight of silver, tungsten in an amount of 200 ppm by weight, cesium in an amount of 350 ppm by weight, lithium in an amount of 190 ppm by weight, and sulfur in an amount of 14 ppm by weight.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 9

220 g of the carrier C were converted into the corresponding catalyst according to general instructions 1.2-1.5. The solution according to general procedure 1.3 contained 2.775 g of a 3.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 10 (not according to the invention) 140 g of the carrier D were converted into the corresponding catalyst according to general instructions 1.2-1.5. The solution according to general procedure 1.3 contained 1.254 g of a 4.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1 .6. The result is shown in Table 2. Example 11

120 g of the carrier D were converted into the corresponding catalyst according to general instructions 1.2-1.5. The solution according to general procedure 1.3 contained 1.318 g of a 4.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1.6. The result is shown in Table 2. Example 12

120 g of the carrier D were converted into the corresponding catalyst according to general instructions 1.2-1.5. The solution according to general procedure 1.3 contained 1.388 g of a 4.1% aqueous rhenium solution prepared by dissolving ammonium perrhenate in water.

The resulting catalyst was tested according to General Procedure 1 .6. The result is shown in Table 2. Table 2

The catalysts marked with ^* are comparative examples

The catalysts marked with ^* did not reach the desired maximum performance. The test of the catalysts based on alumina carriers with different ring geometry shows that when changing the alumina carrier geometry from 6x6x3 [mm x mm x mm] - to 8x8x3 [mm x mm x mm] rings (with otherwise identical alumina carrier properties) the rhenium concentration had to be increased to achieve comparable catalytic properties.

Claims

claims

1 . Catalyst form body for producing ethylene oxide, at least comprising silver and rhenium applied to an alumina support, wherein the alumina support has the geometry of a hollow cylinder and wherein the catalyst form body has a rhenium content C _R and C _R /Gew.-ppm, based on the wall thickness of the hollow cylinder dw / mm, in the range of 120 <C _R / d _w ^ 200.

2. Catalyst molding, wherein the hollow cylinder has a length L in the range 5 to 10 mm, an outer diameter d _A in the range of 5 to 10 mm and a ratio of outer diameter d _A / mm to wall thickness dw / mm in the range of 2.5 to 4 , 5.

3. Catalyst form body according to claim 2, wherein the hollow cylinder has a length L in the range 6 to 9.5 mm.

4. Catalyst form body according to one of claims 1 to 3, wherein the

Catalyst form body silver in an amount of 5 to 30 wt .-%, based on the total weight of the shaped catalyst body and calculated as an element having.

5. Catalyst form body according to one of claims 1 to 4, wherein the

Alumina carrier, preferably the alpha-alumina carrier, has a bimodal pore distribution.

6. Catalyst form body according to one of claims 1 to 5, wherein the

Alumina support has a BET surface area in the range of 0.7 to 1, 2 m ² / g.

7. Catalyst form body according to one of claims 1 to 6, wherein the catalyst is at least one promoter selected from the group consisting of elements of group IA, VIB, VII B and VIA, preferably selected from the group consisting of tungsten, cesium, lithium and sulfur , includes.

8. Catalyst form body according to one of claims 1 to 7, wherein the

Catalyst shaped body tungsten in an amount in the range of 5 to 500 ppm by weight, cesium in an amount in the range of 100 to 800 ppm by weight, lithium in an amount in the range 10 to 500 ppm by weight, and sulfur in an amount in the range of 0 to 50 ppm by weight, calculated as the element and based on the total weight of the shaped catalyst body. A process for preparing a shaped catalyst body comprising silver and rhenium supported on an alumina support comprising

(a) providing an alumina support having the geometry of a

Hollow cylinder has,

(b) depositing silver and rhenium on the alumina support, wherein rhenium is present in an amount of C _R / wt ppm, based on the wall thickness of the hollow cylinder d _w / mm, and calculated as an element in the range of 120 C _R / d _w ^ 200, is applied to the alumina support.

The method of claim 9, wherein the method further comprises

(c) calcining the alumina support obtained in (b).

A process according to claim 9 or 10, wherein in (b) silver is applied in an amount of 5 to 30% by weight, based on the total weight of the shaped catalyst body and calculated as element.

Catalyst shaped article, producible or produced by a process according to one of claims 9 to 11.

Process for the preparation of ethylene oxide by gas phase oxidation of ethene with oxygen in the presence of a shaped catalyst body according to one of claims 1 to 8 or 12.

Use of a shaped catalyst body according to one of claims 1 to 8 or 12 as catalyst for the preparation of ethylene oxide

Gas phase oxidation of ethene with oxygen.