WO2012140614A1

WO2012140614A1 - Process for producing catalyst for oxidation of ethylene to ethylene oxide

Info

Publication number: WO2012140614A1
Application number: PCT/IB2012/051834
Authority: WO
Inventors: Tobias Rosendahl; Torsten Mäurer; Cornelia Katharina Dobner; Thomas Geiger; Achim Gritsch
Original assignee: Basf Se; Basf (China) Company Limited
Priority date: 2011-04-14
Filing date: 2012-04-13
Publication date: 2012-10-18
Also published as: EP2696971A4; EP2696971A1; JP6062417B2; CN103608107B; CN103608107A; JP2014516310A

Abstract

The invention relates to a method for producing a catalyst used for oxidizing ethylene to obtain ethylene oxide, comprising the steps of a) providing a carrier that has a temperature T₀, contains aluminum oxide, and is impregnated with silver or a compound containing silver; and b) heating the impregnated carrier from temperature T₀ to a temperature T₁ at a minimum heating rate of 30 K/min. The invention also relates to the catalyst obtained using said method.

Description

Process for the preparation of a catalyst for the oxidation of ethene to ethylene oxide

The present invention relates to a process for preparing a catalyst which is particularly suitable for the oxidation of ethene to ethylene oxide. In the context of the process according to the invention, a carrier impregnated with an aqueous solution containing a silver-containing compound and containing aluminum oxide is preferably heated by calcination at a heating rate of at least 30 K / min. According to a preferred embodiment, this heating takes place in one

Ribbon calciner that is specifically adapted to the process of the invention.

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. Usually, supported catalysts are used in which the catalytically active, metallic silver has been applied to a support by means of a suitable process. As a carrier material can in principle be different porous

Materials such as activated carbon, titania, zirconia, silica,

Alumina or ceramic compositions or mixtures of these materials are used. Particularly preferred carriers are based on alpha alumina. 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 support in addition to the active material silver. Examples which may be mentioned are alkali and / or alkaline earth metal compounds, tungsten, molybdenum or rhenium, 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, it is the case that the activity of the catalyst is higher Reaching a predetermined concentration of ethylene oxide at the reactor outlet required temperature at otherwise constant

Reaction conditions is.

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

WO 2004/094054 A2 discloses that, in order to activate an impregnated carrier, the temperature of the carrier is first increased to a value of from 120 to 500 ° C. and the carrier, as soon as it has a temperature of more than 300 ° C., to be kept under an inert gas atmosphere. If lower temperatures of at most 300 ° C are used, it is necessary according to WO 2004/094054 A2 to carry out the calcining under air. The same describes WO 03/086624 A1 and WO 01/83105 A1. US 2008/0039316 A1 discloses that the calcination should be designed as a 2-stage process. The first calcination takes place at temperatures up to 270 ° C in air-atmosphere, while the second calcination, which is carried out under inert gas, at temperatures of 200 to 600 ° C is performed. As the examples of US 2008/0039316 A1 show, temperatures of 400 ° C. are reached in the second calcination.

WO 2007/081379 A2 discloses a method for calcination in which a furnace with several heating zones is used. With the disclosed increase in temperature to 400 ° C, the catalyst to be calcined passes a total of 4 zones.

WO 2009/042300 A1 describes calcinations at temperatures of 200 to 600 ° C., more preferably at 200 to 450 ° C., and at different calcination times of less than 300 seconds to 8 hours. Explicitly it is taught that the

Calcination time is insignificant, as long as it is ensured that the duration is suitably correlated with the calcination temperature, in order to achieve that the silver-containing compound applied to the support is completely converted to silver. As for the atmosphere under which the calcination takes place, the WO discloses

2009/042300 A1 an inert gas atmosphere with an oxygen content of 10 ppm to about 21 vol .-%. According to the embodiment calcination temperatures of 450 ° C are used.

EP 1 210 301 A1 discloses the use of a belt calciner for calcining a catalyst. As a calcination atmosphere, it is evident that supercritical steam is used in the exemplary embodiments. Part of the supercritical vapor used for calcination is returned to the calcination, part of the vapor being replaced by fresh steam.

EP 0 764 464 B1 discloses a process for the preparation of a catalyst, wherein during the preparation in a first step a porous support is impregnated with a lithium and a cesium compound and in a second step the impregnated support is impregnated with a silver compound and a cesium compound , Between the two steps, a heat treatment is mandatory. Another

Heat treatment must be carried out after the second impregnation. With respect to the heat treatment, temperatures in the range of 130 to 300 ° C are disclosed and the atmosphere generally air, inert gas or superheated steam disclosed, superheated steam is generally disclosed as particularly preferred and described in the embodiments for both heat treatments.

EP 0 384 312 A1 describes the tempering of a catalyst at temperatures of generally from 180 to 300 ° C., preferably from 220 to 250 ° C. As can be seen from the examples of EP 0 384 312 A1, a circulating air oven is preferably used for tempering. EP 1 086 743 A1 discloses the calcination of a catalyst in an inert gas atmosphere at temperatures of 400 to 700 ° C. Explicitly it is described that

Calcination temperatures of less than 400 ° C are not useful. In contradiction to

Description is used in the embodiment 1 for calcination air.

EP 0 804 289 B1 discloses a stepped impregnation of a carrier, wherein the carrier is first impregnated with a silver solution and subsequently with an alkali metal solution. It is essential that both the silver solution and de

Alkali metal solution are substantially free of water. Based on these nonaqueous solvents and the stepwise impregnation, it is further stated that quite generally the carrier obtained after impregnation by means of the anhydrous alkali metal solution is rapidly dried, temperatures ranging from 100 to 800 ° C and from 200 to 600 ° C are described. From none of the examples of EP 0 804 289 B1 it is apparent which temperature increases in the course of drying after the

Impregnation with alkali metal can actually be adjusted. In addition, all examples of the invention relate to embodiments in which the temperature of drying after impregnation with alkali metal is not higher than 200 ° C. As regards the preceding drying step, ie the drying step after impregnation with silver from an anhydrous solution, rapid drying operations are also disclosed here, for which, for example, successive temperatures of 200 ° C., 300 ° C. and 400 ° C. (see, for example, Examples 2 , 3, 10) or temperatures of 150 ° C, 200 ° C, 250 ° C, 300 ° C and 400 ° C are applicable (Examples 5 and 6) or the temperature is raised continuously to 400 ° C, this heating in a total of 7 zones of a Bandkalzinierers done (see example 3). For those on anhydrous

Catalyst preparation based on impregnation solutions thus urges EP 0 804 289 B1 to require that, after impregnation with silver, different, ever increasing temperatures of up to 400 ° C. be set either in successive steps or in different zones of a ribbon calciner. Examples 8 and 9 disclose that, under certain circumstances, even temperatures of up to 500 ° C. may be necessary, and even at such high temperatures of 500 ° C., for example, seven zones of a ribbon calciner are run through (Example 11). If, in addition to silver, the support is additionally impregnated with alkali metal according to EP 0 804 289 B1, a further impregnation step is taught in each case, which then necessarily entails a further drying step.

An object of the present invention was to provide an improved process for the preparation of catalysts for the oxidation of ethene to ethylene oxide.

Surprisingly, it has been found that for the oxidation of ethene to ethylene oxide

Excellent suitable catalysts can be obtained by first containing a suitable carrier by means of an aqueous, containing a silver-containing compound Impregnating solution, impregnated with silver and then subjected to a rapid heating.

Therefore, the present invention relates to a process for preparing a catalyst for the oxidation of ethene to ethylene oxide, comprising

a) impregnating an alumina-containing support with an aqueous solution containing a silver-containing compound, and providing the impregnated support at a temperature T ₀ ;

b) heating the impregnated carrier from the temperature T ₀ to a temperature Ti at a heating rate of at least 30 K / min.

Step a)

According to step a), an alumina-containing support is impregnated with an aqueous solution containing a silver-containing compound, and the impregnated support is provided at a temperature T ₀ .

Non-impregnated carrier Preferably, the unimpregnated carrier contains from 90 to 99% by weight, more preferably from 92 to 98% by weight, more preferably from 95 to 97% by weight, based on the total weight of the unimpregnated Support, alumina, calculated as Al ₂ O ₃ . While in principle all suitable aluminum oxide phases are conceivable, such as inter alia alpha-alumina, gamma-alumina or tetha-alumina or alumina mixed phases, alpha alumina is particularly preferred in the present invention. Further preferred are at least 95% by weight, more preferably at least 97% by weight, more preferably at least 99% by weight, more preferably at least 99.9% by weight of that contained in the unimpregnated carrier

Alumina alpha alumina.

Therefore, the present invention also relates to the method as described above

a) impregnating an alumina-containing support with an aqueous solution containing a silver-containing compound; and providing the impregnated support at a temperature T ₀ , wherein the unimpregnated support is from 95 to 97

% By weight, based on the total weight of the unimpregnated carrier,

Alumina, calculated as Al ₂ O ₃ , and at least 99% by weight of the

Alumina are alpha alumina;

b) heating the impregnated carrier from the temperature T ₀ to a temperature Ti at a heating rate of at least 30 K / min. According to a further preferred embodiment, the unimpregnated support contains at least one alkali metal, wherein the total alkali metal content of the unimpregnated support preferably in the range of up to 2500 ppm, preferably from 10 to 2500 ppm, more preferably from 50 to 1000 ppm, based in each case the total weight of the non-impregnated carrier and calculated as element.

Most preferably, the non-impregnated carrier contains sodium and / or potassium, more preferably sodium and potassium. When the non-impregnated carrier contains sodium, the sodium content is preferably in the range of 10 to 1500 ppm, more preferably 10 to 800 ppm, further preferably 10 to 600 ppm, further preferably 10 to 500 ppm based on the total weight of the non-impregnated vehicle and calculated as Na. If the unimpregnated carrier contains potassium, the potassium content is preferably at most 1000 ppm, more preferably at most 500 ppm, further preferably at most 200 ppm, for example in the range from 10 to 200 ppm, based on the total weight of the unimpregnated carrier and calculated as K. According to a further preferred embodiment, the unimpregnated support contains at least one alkaline earth metal, wherein the total alkaline earth metal content of the non-impregnated support is preferably up to 2500 ppm, for example in the range of 1 to

2500 ppm, more preferably from 10 to 1200 ppm, more preferably from 100 to 800 ppm, in each case based on the total weight of the carrier and calculated as the element.

Most preferably, the non-impregnated carrier contains calcium and / or magnesium, more preferably calcium and magnesium.

When the unimpregnated carrier contains calcium, the calcium content is preferably in the range of 10 to 1500 ppm, more preferably 20 to 1000 ppm, further preferably 30 to 600 ppm, each based on the total weight of the unimpregnated carrier and calculated as Element.

If the unimpregnated support contains magnesium, the magnesium content is preferably in the range of up to 800 ppm, preferably from 1 to 500 ppm, more preferably from 1 to 250 ppm, more preferably from 1 to 100 ppm, in each case based on the total weight of the non-impregnated vehicle and calculated as an element.

In a preferred embodiment, the unimpregnated support contains silicon in an amount ranging from 50 to 10,000 ppm, preferably from 100 to 5,000 ppm, more preferably from 100 to 2,500 ppm, each based on the total weight of the unimpregnated support and calculated as Si. In one embodiment, the unimpregnated support contains zinc in an amount in the range of from 10 to 1500 ppm, preferably from 10 to 750 ppm, more preferably from 10 to 300 ppm, based on the total weight of the unimpregnated support and calculated as Zn ,

According to one embodiment, the unimpregnated support contains zirconium in an amount in the range of 1 to 10,000 ppm, preferably 10 to 8,000 ppm, more preferably 10 to 6,000 ppm, more preferably 10 to 5,000 ppm, based in each case

Total weight of non-impregnated carrier and calculated as Zr.

In one embodiment, the unimpregnated support contains zinc in an amount ranging from 10 to 1500 ppm, preferably from 10 to 750 ppm, more preferably from 10 to 300 ppm, and zircon in an amount ranging from 1 to 10,000 ppm , preferably from 10 to 8000 ppm, more preferably from 10 to 6000 ppm, more preferably from 10 to 5000 ppm, in each case based on the total weight of the non-impregnated support and calculated as Zn or Zr.

According to another embodiment, the unimpregnated support contains less than 10 ppm zinc and less than 1 ppm zirconium, and according to this embodiment it is preferred that the unimpregnated support contain both zinc and zirconium in an amount below the respective detection limit or both zinc and zirconium free.

According to a preferred embodiment of the present invention, the non-impregnated support has a BET surface area, determined in accordance with DIN ISO 9277, in the range from 0.1 to 5 m ² / g, more preferably in the range from 0.2 to 2 m ² / g, more preferably in the range of 0.3 to 1, 5 m ² / g, more preferably in the range of 0.4 to 1, 4 m ² / g, more preferably in the range of 0.5 to 1.3 m ² / g, more preferably in the range of 0.6 to 1, 2 m ² / g and particularly preferably in the range of 0.7 to 1, 0 m ² / g.

According to a preferred embodiment of the present invention, the non-impregnated support has pores with diameters in the range from 0.1 to 100 μm, the pore distribution preferably being monomodal or polymodal, more preferably polymodal, particularly preferably bimodal. Within the scope of the particularly preferred bimodal pore distribution, the peak maxima obtained by determining the pore diameters according to Hg porosimetry according to DIN 66133 are more preferably in the range from 0.1 to 10 μm and 15 to 100 μm, preferably in the range from 0.1 to 5 μηη and 17 to 80 μηη, more preferably in the range of 0.1 to 3 μηη and 20 to 70 μηη, more preferably in the range of 0.1 to 2.5 μηη and 20 to 65 μηη.

Therefore, the present invention also relates to the method as described above Impregnating an alumina-containing support with an aqueous solution containing a silver-containing compound, and providing the impregnated support at a temperature T ₀ , wherein the unimpregnated support is from 95 to 97% by weight, based on the total weight of the unimpregnated support

Alumina, calculated as Al ₂ O ₃ , and at least 99% by weight of the

Alumina are alpha alumina; and wherein the unimpregnated support has a BET surface area determined in accordance with DIN ISO 9277 in the range from 0.1 to 5 m ² / g, in particular in the range from 0.7 to 1.0 m ² / g;

Heating the impregnated carrier from the temperature T ₀ to a temperature Ti at a heating rate of at least 30 K / min.

Likewise, the present invention also relates to the method as described above comprising

a) impregnating an alumina-containing support with an aqueous solution containing a silver-containing compound, and providing the impregnated support at a temperature T ₀ , wherein the unimpregnated support from 95 to 97 wt .-%, based on the total weight of not impregnated carrier,

Alumina, calculated as Al ₂ O ₃ , and at least 99% by weight of the

Alumina are alpha alumina; and wherein the unimpregnated support has a bimodal pore distribution, the peak maxima determined according to Hg porosimetry according to DIN 66133 being in the range from 0.1 to 10 μm and 15 to 100 μm, in particular in the range from 0.1 to 2, 5 μηη and 20 to 65 μηη are;

Preferably, the present invention also relates to the method as described above comprising

a) impregnating an alumina-containing support with an aqueous solution containing a silver-containing compound, and providing the impregnated support at a temperature T ₀ , wherein the unimpregnated support of 95 to 97 wt .-%, based on the total weight of not impregnated carrier,

Alumina, calculated as Al ₂ O ₃ , and at least 99% by weight of the

Alumina are alpha alumina; and wherein the unimpregnated support has a bimodal pore distribution, the peak maxima determined according to Hg porosimetry according to DIN 66133 being in the range from 0.1 to 10 μm and 15 to 100 μm, in particular in the range from 0.1 to 2, 5 μηη and 20 to 65 μηη and wherein the non-impregnated support has a BET surface area, determined according to DIN ISO 9277, in the range of 0.1 to 5 m ² / g, in particular in the range of 0.7 to 1, 0th m ² / g; b) heating the impregnated carrier from the temperature T ₀ to a temperature Ti at a heating rate of at least 30 K / min. The geometric shape of the unimpregnated support used according to the invention is basically arbitrary and can in principle be adapted to the specific requirements imposed on the catalyst when it is used in the gas-phase oxidation of ethene to ethylene oxide. Conveniently, the carrier has a geometry which allows unimpeded diffusion of the reaction gases used and occurring in this reaction to the largest possible part of the with the catalytically active, with

Silver particles occupied and optionally with other promoters occupied outer and inner surface of the carrier allow. According to a preferred embodiment, the carrier used according to the invention has the geometry of a strand such as a hollow strand, a star, a sphere, a ring, or cylinder. Preferably, according to the invention, a carrier is used which has the geometry of a cylinder. Further preferred is a support having the geometry of a cylinder, the cylinder having 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 outer diameter / mm to wall thickness / mm in the range of 2 , 5 to 4.5.

Particularly preferred are cylinders with the following geometries (outer diameter x length x inner diameter, in each case in mm): 5x5x2, 6x6x3, 7x7x3, 8x8x3, 8x8.5x3, 8x8.5x3.5, 8.5x8x3.5, 8.5x8x3, 9x9x3, 9.5x9x3, 9.5x9x3.5. Each length specification includes tolerances in the range of ± 0.5 mm.

The impregnation of the carrier is carried out as described above by means of an aqueous solution containing a silver-containing compound. Particularly preferred in the context of the present invention is a vacuum impregnation. In the context of this vacuum impregnation, the support is preferably first subjected to a vacuum treatment, the support being exposed to a pressure in the range of preferably at most 500 mbar, more preferably at most 250 mbar, more preferably at most 100 mbar such as 10 to 100 mbar or 20 to 100 mbar becomes. Preferably, the vacuum treatment is carried out at a temperature in the range of 1 to 80 ° C, more preferably from 3 to 50 ° C, more preferably from 5 to 30 ° C, and most preferably at room temperature. Preferably, the vacuum treatment is carried out for a period of at least 1 minute, preferably of at least 5 minutes, more preferably for a period in the range of 5 to 120 minutes, more preferably from 10 to 45 minutes, further preferably from 15 to 30 minutes. Following the

Vacuum treatment, the carrier is brought into contact with the aqueous solution containing the silver-containing compound for the purpose of impregnation. The aqueous solution is preferably added dropwise or sprayed on, more preferably added dropwise.

As far as the chemical nature of the compound containing silver is concerned, there are in principle no restrictions, as long as it is guaranteed that these are

Compound-containing aqueous solution, the silver can be suitably applied to the support. It is also possible that the aqueous solution contains two or more mutually different silver-containing compounds. Are preferred as silver containing compounds according to the invention used Ag (I) oxide or Ag (I) oxalate, with Ag (I) oxalate is particularly preferred.

If necessary, the aqueous solution may contain, in addition to the silver-containing

Compound containing a complexing agent. Preferred complexing agents are amines such as ethanolamine or ethylenediamine. Especially preferred is ethylenediamine. If the aqueous solution contains such a complexing agent, in the aqueous solution the silver is at least partially in the form of the corresponding one

Silver complex compound.

As for the concentration of the aqueous solution on the silver-containing compound, it is preferably in the range of 25 to 35% by weight, more preferably in the range of 27 to 32% by weight, and more preferably in the range of 28 to 30% by weight .-%. In the impregnation according to the invention an impregnated support is preferably prepared whose silver content, calculated as elemental Ag, in the range of 1 to 50 wt .-%, preferably in the range of 5 to 35 wt .-% and more preferably in the range of 10 to 25 wt. -%, in each case based on the weight of the present invention calcined carrier is.

According to a particularly preferred embodiment of the process according to the invention, the impregnation of the carrier according to a) provides an impregnated carrier which contains at least one promoter in addition to silver. Preferred promoters are, for example, rhenium, tungsten, lithium, cesium and sulfur. In principle, any of these promoters can be applied to the support separately from silver in a suitable form. It is conceivable that, for example, each promoter is applied in a separate impregnation step. In principle, either a drying step and / or a calcination step can be carried out between the individual impregnation steps.

Accordingly, the present invention also relates to the process as described above, wherein according to a) the alumina-containing support additionally with rhenium or with a rhenium-containing compound, preferably further additionally with tungsten or with a tungsten-containing compound and / or with lithium or with a lithium containing compound and / or with cesium or with a cesium-containing

Compound is impregnated and wherein the support is optionally impregnated with sulfur or with a sulfur-containing compound.

In the context of the present invention, however, it is particularly preferred to use the promoter or the promoters together with the silver in a single step by impregnating the support with an aqueous solution containing, in addition to the silver-containing compound, in addition a promoter-containing compound or additional promoters-containing compounds contains to apply to the carrier. Therefore, the present invention preferably relates to the method as described above, wherein according to a) the aqueous solution containing a silver-containing compound additionally comprises a rhenium-containing compound, a tungsten-containing compound, a lithium-containing compound, a cesium-containing compound and optionally a sulfur contains containing compound.

The process according to the invention is therefore characterized, inter alia, by the fact that in step a) the unimpregnated support is prepared in a single step by means of a single aqueous solution containing both silver and all promoters, in particular rhenium, tungsten, lithium, cesium and optionally Sulfur, is impregnated, which is to contain the catalyst ultimately obtained. Since the unimpregnated support is impregnated with both silver and the promoters in this single step, it is eliminated

any necessary intermediate treatments, such as drying or calcination, which may be incurred in processes with several impregnation steps.

The present invention therefore relates to a process as described above, wherein during step a) both silver and all promoters, preferably rhenium, tungsten, lithium, cesium and optionally sulfur, by impregnation in a single

Impregnation step, wherein during step a) no drying and no calcining is carried out, and wherein after step a) the impregnated support is subjected exclusively to the heat treatment according to steps b) and optionally c) and d), as described below.

The aqueous solution by means of which in step a) of the process according to the invention both silver and the promoters are applied to the support by impregnation, contains as rhenium-containing compound preferably a halide, an oxyhalide, an oxide, an acid or a salt of a heteropolyacid of the Rhenium, such as a rhenate or perrhenate. Preferably, the rhenium-containing compound is a

A compound selected from the group consisting of ammonium perrhenate, rhenium (III) chloride, rhenium (V) chloride, rhenium (V) fluoride, rhenium (VI) oxide, and rhenium (VII) oxide. Particularly preferred is ammonium perrhenate. As for the concentration of the aqueous solution on the rhenium-containing compound, it is preferably in the range of 1 to 5 wt%, more preferably in the range of 2 to 4.5 wt%, and more preferably in the range of 2, 8 to 4.2 wt .-% rhenium, each calculated as an element. At the

impregnation according to the invention is preferably prepared an impregnated support whose rhenium content, calculated as elemental Re, in the range of 100 to 1000 ppm, preferably in the range of 100 to 600 ppm and more preferably in the range of 250 to 500 ppm, each based on the weight of According to the invention calcined carrier lies. The aqueous solution, by means of which in step a) of the process according to the invention both silver and the promoters are applied to the support by impregnation, contains as tungsten-containing compound preferably a tungsten salt or tungstic acid. Particularly preferred is tungstic acid. As for the concentration of the aqueous solution to the tungsten-containing compound, it is preferably in the range of 0.1 wt .-% to 5 wt .-%, more preferably in the range of 0.5 wt .-% to 3 wt. -%, and more preferably in the range of 0.8 wt .-% to 2.5 wt .-% tungsten, each calculated as an element. In the impregnation according to the invention an impregnated support is preferably prepared whose tungsten content, calculated as elemental W, in the range of 10 to 500 ppm, preferably in the range of 50 to 300 ppm, and more preferably in the range of 80 to 250 ppm, in each case by weight of the invention calcined carrier lies.

The aqueous solution by means of which in step a) of the process according to the invention both silver and the promoters are applied to the support by impregnation, contains as lithium-containing compound preferably at least partially

water-soluble lithium salt. Particularly preferred is lithium nitrate. As for the concentration of the aqueous solution on the lithium-containing compound, it is preferably in the range of 0.5 to 5% by weight, more preferably in the range of 1 to 4% by weight, and more preferably in the range of 1, 5 to 3% by weight of lithium calculated as element. In the impregnation according to the invention an impregnated support is preferably prepared whose lithium content, calculated as elemental Li, in the range of 10 to 500 ppm, preferably in the range of 50 to 400 ppm, and more preferably in the range of 100 to 250 ppm, in each case by weight of the invention calcined carrier lies.

The aqueous solution by means of which in step a) of the process according to the invention both silver and the promoters are applied to the support by impregnation, contains as the cesium-containing compound preferably at least partially water-soluble cesium salt. Particularly preferred is cesium hydroxide. As for the concentration of the aqueous solution on the cesium-containing compound, it is preferably in the range of 0.5 to 6% by weight, more preferably in the range of 1.5 to 5.5% by weight, and more preferably in the range of Range of 3 wt .-% to 5 wt .-% cesium calculated as element. In the impregnation according to the invention, an impregnated support is preferably prepared whose cesium content, calculated as elemental Cs, is in the range from 100 to 800 ppm, preferably in the range from 200 to 700 ppm and more preferably in the range from 250 to 600 ppm, in each case by weight of the invention calcined carrier lies.

The aqueous solution by means of which in step a) of the process according to the invention both silver and the promoters are applied to the carrier by impregnation, optionally contains, as sulfur-containing compound, ammonium sulfate. As for the concentration of the aqueous solution on the sulfur-containing compound, it is preferably in the range of 0.05 to 0.5 wt%, more preferably in the range of 0.1 to 0.35 wt%, and more preferably in the range of 0.15 to 0.3% by weight of sulfur calculated as the element. In the impregnation according to the invention an impregnated support is preferably prepared whose sulfur content, calculated as elemental S, in the range of 0 to 50 ppm, preferably in the range of 2 to 30 ppm and more preferably in Range of 5 to 20 ppm, each based on the weight of the present invention calcined carrier.

According to a preferred embodiment of the method according to the invention, the impregnation solution is prepared from a solution containing tungsten and cesium, a solution containing lithium and sulfur, and a solution containing rhenium. These three solutions contain the stated promoters in quantities, so that the mixing of the three solutions gives an impregnating solution containing the promoters in the abovementioned amounts.

Temperature Tn

According to the process of the invention, in step a) the silver-containing or silver-containing compound-impregnated, alumina-containing support as described above is provided at a temperature T ₀ . Should be incurred in the context of impregnation, especially in the context of the particularly preferred one-step impregnation of the impregnated support at a temperature greater than T ₀ , it is inventively cooled first to the temperature T ₀ . In principle, temperatures T ₀ in the range of up to 35 ° C such as in

Range of up to 30 ° C conceivable. Preferably, the temperature T _{0 is} in the range of 5 to 20 ° C, more preferably in the range of 5 to 15 ° C.

In the context of the preferred embodiments according to the invention is achieved in view of the temperature T ₀ that provided in step a) carrier, according to the described above impregnation, is not subjected to pre-drying before

is heated according to the invention in step b) with a heating rate of at least 30 K / min. The present invention thus preferably relates to a process in which the catalyst obtained after impregnation of the support as described above is not exposed to a temperature greater than 35 ° C., preferably greater than 30, before heating at a heating rate of at least 30 K / min ° C, more preferably greater than 25 ° C and more preferably greater than 20 ° C.

Step b)

According to step b) of the process according to the invention, the impregnated support provided at the temperature T ₀ is heated at a heating rate of at least 30 K / min.

In principle, heating rates of up to 150 K / min, for example up to 100 K / min or up to 80 K / min are conceivable. The heating rate in step b) is preferably in the range from 30 to 80 K / min, more preferably in the range of 30 to 75 K / min, more preferably in the range of 30 to 70 K / min.

In step b) of the method according to the invention, the carrier is heated from the temperature T ₀ to the temperature Ti.

According to the invention is heated to temperatures T-i, the calcination of the

impregnated carrier are suitable. In principle, temperatures T-i of up to 350 ° C, for example of up to 340 ° C or up to 330 ° C or up to 320 ° C or up to 310 ° C or up to 300 ° C are conceivable. Preferred minimum temperatures T-i are in

Range of 250 ° C. Accordingly, temperatures T-i in the range from 250 to 310 ° C. or in the range from 250 to 300 ° C. are conceivable. According to the invention, however, it has been found that it is possible to set calcining temperatures of less than 300 ° C. Therefore, the present invention relates to the method as described above, wherein the temperature T-i is less than 300 ° C, preferably less than or equal to 299 ° C.

According to the invention, the temperature Ti is preferably in the range from 250 to 295.degree. C., more preferably in the range from 260 to 295.degree. C., more preferably in the range from 270 to 295.degree. C., more preferably in the range from 270 to 290.degree Range from 270 to 285 ° C, 275 to 290 ° C, or 275 to 285 ° C.

As far as the manner in which the heating rate according to the invention is achieved, there are basically no restrictions. Preferably, in the context of heating the present at the temperature T ₀ carrier is brought into contact with a gas, wherein more preferably the heating of the carrier takes place via this gas, the gas thus a

Temperature, which allows to heat the carrier to the temperature T-i.

As for the chemical composition of the gas which is brought into contact with the carrier for heating the carrier, there are basically none

Restrictions. Thus, it is conceivable that the gas contains oxygen, for example, oxygen contents of the gas of up to 100 vol .-% or up to 25 vol .-% may be mentioned. It is conceivable, for example, the use of air. Lower levels of oxygen are also conceivable, for example, mixtures of nitrogen and air such as lean air are conceivable. Oxygen contents of the gas of up to 20 vol.% Or up to 15 vol.% Or up to 10 vol.% Or up to 5 vol.% Or up to 1 vol.% Can be mentioned. In the context of the present invention, it is particularly preferred to use as gas for heating an inert gas or a mixture of two or more inert gases, wherein the oxygen content is preferably less than 10 ppm, more preferably in the range of 5 to 9 ppm. As inert gases are exemplified nitrogen, carbon dioxide, argon and / or helium to mention. Nitrogen is particularly preferably used as the inert gas in the context of the present invention. Accordingly, the present invention relates to the method as described above, wherein the heating according to b) by means of contacting the carrier with an inert gas \ ^ _\ done.

Preferably, the present invention relates to the process as described above, wherein the heating according to b) by contacting the support is carried out with an inert gas \ ^ _\, wherein the inert gas contains less than 10 ppm, preferably from 5 to 9 ppm, oxygen.

More preferably, the present invention relates to the process as described above, wherein the heating according to b) by contacting the support is carried out with an inert gas \ ^ _\, wherein the inert gas is nitrogen and the inert gas is less than 10 ppm, preferably from 5 to 9 ppm, Contains oxygen.

The term "inert gas \ ^ _\, containing less than 10 ppm, preferably from 5 to 9 ppm oxygen" herein refers to a gas mixture consisting of the inert gas \ ^ _\ and oxygen, wherein the oxygen content of less than 10 ppm, or from 5 to 9 ppm refers to the oxygen content of the gas mixture, and wherein the inert gas \ ^ _\ may be a mixture of 2 or more inert gases.

In the context of the present invention, it is very particularly preferred as a gas with which the support is brought into contact as part of the heating in step b)

Nitrogen, preferably obtained from air separation, typically containing nitrogen in the range of 99.995 to 99.9999% by volume, oxygen in the range of 6 to 8 ppm and in traces of noble gases. The temperature of the gas with which the support is brought into contact in the course of heating is in principle selected so that the heating rates according to the invention can be made possible and the support can be brought to the temperature T-i. Preferably, the gas with which the carrier is brought into contact in the course of heating in step b), a temperature in the range of Ti to 1, 1 Ti, more preferably in the range of Ti to 1, 07 Ti, more preferably in the range from Ti to 1, 05 Ti up.

The contacting of the carrier with the gas in the context of step b) can in principle be carried out arbitrarily, as long as it is ensured that the heating rate of the carrier according to the invention is achieved. In this regard, it is particularly preferred to bring the carrier with a stream of gas, preferably with a flow of inert gas \ ^ _\ in contact, that is to flow through the support with the gas. In this case, the volume flow of the gas is basically chosen so that the heating rate according to the invention is achieved.

In particular, the volumetric flow rate of the gas is selected such that the heating rate according to the invention is achieved with the combination of the temperature and the volumetric flow of the gas which is brought into contact with the carrier. Particularly preferred is the

Volume flow in the range from 2500 to 5000 m ³ / h, in particular preferably in the range from 3200 to 4500 m ³ / h. According to a preferred embodiment, the present invention relates to the method as described above, wherein the carrier to be heated according to b) is flowed through by an inert gas, preferably nitrogen, wherein preferably less than 10 ppm, more preferably from 5 to 9 ppm, oxygen, wherein preferably has a temperature in the range of Ti to 1, 1 Ti and wherein the carrier is preferably with a

Volume flow in the range of 2500 to 5000 m ³ / h, more preferably from 3200 to 4500 m ³ / h, flows through. As part of the heating of the carrier according to step b), the heating rate may be constant or vary as long as it is ensured that the total heating rate, calculated from the temperature difference (TT ₀ ) divided by the time required for the entire heating, at least 30 K. min, and preferably in the range of 30 to 80 K / min, more preferably in the range of 30 to 75 K / min, more preferably in the range of 30 to 70 K / min. During the entire heating process, the heating rate is preferably at least 30 K / min, more preferably in the range from 30 to 80 K / min, more preferably in the range from 30 to 75 K / min, even more preferably in the range from 30 to 70 K. / min.

Possible ranges for the heating rate according to the invention are, for example, 35 to 80 K / min or 40 to 75 K / min or 40 to 70 K / min or 45 to 70 K / min or 50 to 70 K / min or 55 to 70 K / min or 60 to 70 K / min or 65 to 70 K / min.

Step c) According to a preferred embodiment, the support heated to the temperature Ti is maintained at a temperature T ₂ , which is suitable for the purposes of the calcination according to the invention, following the heating, preferably in direct connection to the heating. In this case, temperatures T ₂ which are in the region of the temperature Ti are preferred. Particularly preferred are temperatures T ₂ , which are in the range of 0.90 to 1, 1 Ti, such as in the range of 0.95 to 1, 05 Ti, 0.96 to 1, 04 Ti, 0.97 to 1, 03rd Ti, 0.98 to 1, 02 Ti, or 0.99 to 1, 01 Ti lie. Preferably, the temperature T ₂ is chosen so that it is less than 300 ° C, preferably less than or equal to 299 ° C.

Therefore, the present invention also relates to the method as described above, further comprising

c) holding the heated to the temperature Ti carrier at a temperature T ₂ , wherein

T ₂ preferably ranges from 0.90 Ti to 1.1 Ti,

wherein, more preferably, the temperature T _{2 is} less than 300 ° C, preferably less than or equal to 299 ° C.

The holding of the carrier at the temperature T ₂ also includes embodiments in which, while being held, the value of T _{2 is} not constant, but within the above varies. Among other things, the present invention thus also encompasses embodiments according to which the holding takes place at two or more different temperatures, wherein these temperatures are within the limits T ₂ described above.

The duration of holding the carrier at the temperature T ₂ is basically not limited. In the context of the present invention, it is preferred that in c) the support be maintained at the temperature T ₂ for a time in the range from 1 to 15 minutes, preferably from 2 to 10 minutes, more preferably from 3 to 5 minutes.

As far as the manner in which the holding according to the invention according to step c) is achieved, there are basically no restrictions. Preferably, in the course of holding at the temperature T _2, the carrier is brought into contact with a gas, wherein further the gas has a temperature which makes it possible to keep the carrier at the temperature T ₂ .

As for the chemical composition of the gas, which is brought into contact with the carrier for holding the carrier at the temperature T ₂ , there are basically no restrictions. For example, it is conceivable that the gas contains oxygen, for example oxygen contents of the gas of up to 100% by volume or up to 25% by volume. It is conceivable, for example, the use of air. Lower levels of oxygen are also conceivable, for example, mixtures of nitrogen and air such as lean air are conceivable. Mention may be made of oxygen contents of the gas of up to 20% by volume or up to 15% by volume or up to 10% by volume or up to 5% by volume or up to 1% by volume. In the context of the present invention, it is particularly preferred to use as the gas for holding at the temperature T ₂ an inert gas or a mixture of two or more inert gases, wherein the oxygen content is preferably less than 10 ppm, more preferably in the range of 5 to 9 ppm lies. Examples of inert gases include nitrogen, carbon dioxide, argon and helium. Nitrogen is particularly preferably used as the inert gas in the context of the present invention.

Accordingly, the present invention relates to the method as described above, wherein the holding according to c) takes place by means of contacting the carrier with an inert gas l ₂ . Preferably, the present invention relates to the method as described above, wherein the holding according to c) is carried out by contacting the carrier with an inert gas l ₂ , wherein the inert gas contains less than 10 ppm, preferably from 5 to 9 ppm oxygen.

More preferably, the present invention relates to the method as described above, wherein the holding according to c) takes place by contacting the support with an inert gas l ₂ , wherein the inert gas is nitrogen and the inert gas contains less than 10 ppm, preferably from 5 to 9 ppm oxygen , The term "inert gas l ₂ , which contains less than 10 ppm, preferably from 5 to 9 ppm of oxygen" here denotes a gas mixture consisting of the inert gas l ₂ and oxygen, wherein the oxygen content of less than 10 ppm or from 5 to 9 ppm refers to the oxygen content of the gas mixture and wherein the inert gas is a ₂ l

Mixture of 2 or more inert gases may be.

In the context of the present invention, the use of technical nitrogen, preferably obtained from air separation, which is typically nitrogen in the range from 99.995 to 99, is most preferably used as the gas with which the carrier is brought into contact during the holding in step c). 9999 vol .-%, oxygen in the range of 6 to 8 ppm and traces of noble gases.

Therefore, the present invention relates to the method as described above, wherein the holding according to c) by means of an inert gas l ₂ , preferably by means of nitrogen, wherein the inert gas l ₂ preferably contains less than 10 ppm, more preferably from 5 to 9 ppm oxygen.

The temperature of the gas with which the carrier is brought into contact in the course of holding according to c) is basically chosen so that the inventive

Holding temperature can be enabled. The gas with which the carrier is brought into contact in the context of holding in step c) preferably has a temperature in the range from T ₂ to 1.1 T ₂ , more preferably in the range from T ₂ to 1.7 T ₂ , more preferably in the range of T ₂ to 1, 05 T ₂ such as in the range of T ₂ to 1, 04 T ₂ or in the range of T ₂ to 1, 03 T ₂ or in the range of T ₂ to 1, 02 T ₂ or in the range of T ₂ to 1, 01 T ₂ .

The contacting of the carrier with the gas in the context of step c) can in principle be carried out arbitrarily, as long as it is ensured that the holding of the carrier according to the invention is achieved at the temperature T ₂ . In this regard, it is particularly preferred to bring the carrier into contact with a stream of the gas, preferably with a stream of the inert gas l ₂ , that is to flow through the carrier with the gas. It is the

Volume flow of the gas in principle so that holding of the carrier according to the invention at the temperature T ₂ is obtained chosen. In particular, the volume flow of the gas is chosen so that is achieved with the combination of the temperature and the volume flow which is brought into contact with the carrier gas, the carrier holding the invention at the temperature T _2. Particularly preferably, the volume flow is in the range from 1000 to 3000 m ³ / h, more preferably from 1500 to 2000 m ³ / h.

According to a preferred embodiment, the present invention relates to the method as described above, wherein the carrier to be held according to c) at the temperature T _{2 is} traversed by an inert gas l ₂ , preferably nitrogen, wherein l _{2 is} preferably less than 10 ppm, more preferably contains from 5 to 9 ppm of oxygen, wherein l _{2 is} preferably a Having temperature in the range of T ₂ to 1, 05 T _2, and L _{2 is} preferably flows through the support at a flow rate in the range of 1000 to 3000 m ³ / h, more preferably 1500 to 2000 m ³ / h. Preferably, but not necessarily, in the context of the present invention as the inert gas l _2, the inert gas \ ^ _\ used, where, as described above, the volume flow of l ₂ from the volume flow of \ i and / or the temperature of l ₂ of the temperature can be different from \ i or can be. Step d)

According to a preferred embodiment, the carrier held at the temperature T _{2 is} cooled to a temperature T ₃ following the holding, preferably in direct connection to the holding. Basically, there are no particular restrictions with regard to the value for T ₃ . In the context of the present invention, temperatures T ₃ of at most 60 ° C. are preferred.

Therefore, the present invention relates to the method as described above, further comprising

d) cooling the held at the temperature T ₂ carrier to a temperature T ₃ , wherein T _{3 is} at most 60 ° C.

As far as the manner in which the cooling according to the invention according to step d) is achieved, there are basically no restrictions. Preferably, in the course of cooling to the temperature T _3, the carrier is brought into contact with a gas, wherein furthermore the gas has a temperature which makes it possible to cool the carrier to the temperature T ₃ .

As for the chemical composition of the gas which is brought into contact with the carrier to cool the carrier to the temperature T ₃ , there are basically no limitations. For example, it is conceivable that an inert gas is used as the gas, as used for example in steps b) or c). In the context of the present invention, it is particularly preferred as gas for cooling to the temperature T _3, a gas having an oxygen content of at least 5 vol .-%, preferably at least 10 vol .-%, more preferably at least 15 vol .-%, further preferably at least 20% by volume. Particular preference is given to using air according to the invention for cooling according to d).

Therefore, the present invention relates to the method as described above, wherein the cooling according to d) in an atmosphere containing at least 5 vol .-%, preferably at least 15 vol .-% oxygen, more preferably in air, takes place. In the process according to the invention, the support in step d) is preferably used with a

Cooling cooled, which is in the range of 30 to 80 K min, preferably in the range of 40 to 60 K min, more preferably in the range of 45 to 55 K min. Subsequent to step d), the correspondingly obtained, calcined and cooled carrier can either be used directly as a catalyst or else be suitably stored.

According to a preferred embodiment, the present invention relates to a process for preparing a catalyst for the oxidation of ethene to ethylene oxide, comprising a) providing a compound containing silver or with a silver

impregnated, alumina-containing carrier of a temperature T ₀ ;

b) heating the impregnated carrier from the temperature T ₀ to a temperature Ti at a heating rate of at least 30 K min, the temperature Ti is less than 300 ° C and the heating takes place by contacting the carrier with an inert gas li, wherein the inert gas Nitrogen is, and the inert gas contains less than 10 ppm of oxygen.

According to a preferred embodiment, the present invention also relates to a process for the preparation of a catalyst for the oxidation of ethene to ethylene oxide, comprising

a) providing a compound containing silver or a silver

impregnated, alumina-containing carrier of a temperature T ₀ ;

b) heating the impregnated carrier from the temperature T ₀ to a temperature Ti at a heating rate of at least 30 K min, wherein the temperature Ti is less than

300 ° C and the heating is carried out by contacting the carrier with an inert gas L-i, wherein the inert gas is nitrogen, and the inert gas contains less than 10 ppm of oxygen;

c) holding the carrier heated to the temperature Ti at a temperature T ₂ , wherein T _{2 is} less than 300 ° C and holding by contacting the carrier with a

Inertgas l ₂ takes place, wherein the inert gas is nitrogen and the inert gas contains less than 10 ppm oxygen.

a) providing a compound containing silver or a silver

impregnated, alumina-containing support of a temperature T ₀ in the range of 5 to 15 ° C;

b) heating the impregnated carrier from the temperature T ₀ to a temperature Ti in the range of 275 to 285 ° C at a heating rate of at least 30 to 70 K / min, wherein the heating means contacting the support with an inert gas \ - occurs _\, wherein the inert gas is nitrogen and the inert gas contains 5-9 ppm oxygen; c) holding the carrier heated to the temperature Ti at a temperature T ₂ , wherein T _{2 is} in the range of 0.90 Ti to 1, 1 Ti and held by contacting the carrier with an inert gas l ₂ , wherein the inert gas is nitrogen is, and the inert gas contains from 5 to 9 ppm of oxygen.

a) providing a compound containing silver or a silver

b) heating the impregnated support from the temperature T ₀ at a temperature Ti in the range between 275 and 285 ° C at a heating rate of at least 30 to 70 K / min, said heating means contacting the support is carried out with an inert gas \ ^ _\, wherein the inert gas is nitrogen and the inert gas contains from 5 to 9 ppm oxygen; c) holding the carrier heated to the temperature Ti at a temperature T ₂ , wherein T _{2 is} in the range of 0.90 Ti to 1, 1 Ti and held by contacting the carrier with an inert gas l ₂ , wherein the inert gas is nitrogen and the inert gas contains from 5 to 9 ppm of oxygen;

d) cooling the temperature of the carrier T ₂ held at a temperature T ₃ , wherein T _{3 is} at most 60 ° C and the cooling according to d) in an atmosphere containing at least 15 vol .-% oxygen.

Surprisingly, it has been found that the carrier heated with the high heating rate according to the invention in step a), in particular that in the manner described above

Inertgasatmosphäre heated carrier has advantageous properties as a catalyst in the oxidation of ethene to ethylene oxide.

Therefore, the present invention also relates to a catalyst for the oxidation of ethene to ethylene oxide, obtainable or obtained by a process as described above.

Likewise, the present invention also relates to a process for the production of ethylene oxide by gas phase oxidation of ethene by means of molecular oxygen in one

Fixed bed reactor in the presence of this catalyst.

Band calciner As far as the apparatus configuration of the method according to the invention is concerned, there are essentially no restrictions, as long as it is ensured that the

Heating according to the invention according to b), preferably further holding the invention according to c), preferably further cooling according to the invention according to d), as described above can be carried out. According to the invention are preferred

Embodiments according to which at least the heating according to b), preferably the heating according to b) and the holding according to c), and optionally also the cooling according to d), are carried out continuously. This is particularly preferred

Process according to the invention, at least with regard to step b), preferably at least with regard to steps b) and c) in a belt calciner.

In principle, the strip calciner preferably used according to the invention can have one or more heating zones in which step b) is carried out. Does the

Bandkalzinierer on several heating zones, in each heating zones identical gases, preferably inert gases are used, each of which may have different oxygen contents and / or different temperatures, and wherein in each heating different volumetric flows of the gases can be adjusted. According to the invention it has been found that it is due to the large

Heating rate of at least 30 K / min is sufficient that the used Bandkalzinierer only a single heating zone, which means that the Bandkalzinierer is less expensive to design with respect to the heating zone. Furthermore, the strip calciner preferably used according to the invention can have one or more holding zones, in which step c) is carried out. If the belt calciner has a plurality of holding zones, identical gases, preferably inert gases l ₂ , can be used in the individual holding zones, each of which can have different oxygen contents and / or different temperatures, and different volumetric flows of the gases can be set in the individual holding zones , According to the invention, it has been found that it is sufficient for the belt calciner used to have only a single holding zone, which means that the belt calciner is not very expensive to construct, not only with regard to the heating zone but also with regard to the holding zone. In the context of the present invention, it is particularly preferred for the holding zone or the first of the plurality of holding zones to be provided immediately after the heating zone or the last of the several heating zones in the belt calciner.

As regards the preferred parameters with regard to the heating according to step b) and the holding according to step c), reference is made to the above statements.

Accordingly, the present invention relates to the method as described above, wherein the Bandkalzinierer has exactly one heating zone, wherein in the heating zone of the carrier to be heated in accordance with b) is traversed by an inert gas, preferably nitrogen, preferably, less than 10 ppm, more preferably from 5 to 9 ppm oxygen, wherein preferably a temperature in the range of Ti to 1, 1 Ti, more preferably from Ti to 1, 07 Ti, more preferably from Ti to 1, 05 Ti, and wherein the carrier is preferably with a flow rate in the range of 2500 to 5000, more preferably from 3200 to 4500 m ³ / h, flows through.

According to a particularly preferred embodiment of the present invention, the gas stream introduced into the heating zone is suitably heated to the temperature in the range of ΤΊ to 1.1 Ti, more preferably in the range of ΤΊ to 1.7 Ti, more preferably in the range before introduction from ΤΊ to 1, 05 Ti, heated.

The present invention further relates to the method as described above, wherein the belt calciner has exactly one holding zone following the heating zone, wherein in the holding zone a holding of the carrier heated to the temperature Ti takes place at a temperature T ₂ , and in the holding zone carriers held at the temperature T ₂ is flowed through by an inert gas, l _2, preferably nitrogen, where l _{2 is} preferably less than 10 ppm, more 5-9 ppm preferably contains oxygen, wherein l _{2 is} preferably a temperature in the range of T ₂ to 1, 05 T ₂ , and wherein l ₂ preferably flows through the carrier with a volume flow in the range of 1000 to 3000, more preferably from 1500 to 2000 m ³ / h.

In a particularly preferred embodiment of the present invention, the introduced into the holding zone gas stream prior to insertion in an appropriate manner, to the temperature in the range of T ₂ to 1, 1 T _2, more preferably in the range of T ₂ to 1, 07 T ₂ more preferably in the range of T ₂ to 1, 05 T ₂ such as in the range of T ₂ to 1, 04 T ₂ or in the range of T ₂ to 1, 03 T ₂ or in the range of T ₂ to 1, 02 T ₂ or in the range of T ₂ to 1, 01 T ₂ , heated.

According to the present invention, in addition to the at least one, preferably exactly one heating zone and the at least one, preferably exactly one holding zone, the preferred belt calciner may comprise at least one cooling zone for performing step d), particularly preferably in the belt calciner immediately following the holding zone or the last of the holding zones is provided.

As regards the preferred parameters with regard to the cooling according to step d), reference is made to the above statements. Accordingly, the present invention also relates to the method as described above, wherein the belt calciner has a cooling zone following the holding zone and, in the cooling zone, cooling the carrier held at the temperature T ₂ to one

Temperature T ₃ , preferably at most 60 ° C, takes place. Likewise, the present invention also relates to the method as described above, wherein the belt calciner has a cooling zone following the holding zone and in the

Cooling zone, a cooling of the held at the temperature T ₂ carrier on a Temperature T ₃ , preferably at most 60 ° C, takes place, and the cooling according to d) in an atmosphere containing at least 15 vol .-% oxygen.

In the context of the present invention, either at least one of the heating zones, preferably the exactly one heating zone and / or at least one of the holding zones, preferably the exactly one holding zone and / or at least one of the cooling zones, preferably the exactly one cooling zone increased compared to the ambient pressure or have reduced pressure. If one of these zones has a pressure which is lower than the ambient pressure, the pressure is, for example, at pressures which are lower than atmospheric pressure, up to 10 mbar, preferably up to 5 mbar. If one of these zones has a pressure which is higher than the ambient pressure, the pressure is, for example, at pressures which are up to 10 mbar, preferably up to 5 mbar, compared with the ambient pressure. In accordance with the invention are preferably used belt calciner according to a preferred embodiment of the method according to the invention, the gas stream, preferably the flow of the inert gas \ ^ _\, performed in a single pass through the heating zone, whereby further preferably the gas flow from the top downward through the heating zone is passed. The term "straight passage", as used in this context, denotes a process procedure in which the gas stream is introduced into the heating zone and passed through the carrier substantially without mixing and is then discharged from the heating zone substantially without mixing and wherein it is additionally ensured that, after contact of a given volume element of the gas stream with the carrier, this volume element no longer comes into contact with the carrier It has been found within the scope of the present invention that such a straight passage is advantageous in order to achieve the high heating rates according to the invention In order to ensure such a straight passage, it has further proved expedient to dispense with devices, such as fans, which are usually provided in belt calciners and over which circulates the gas atmosphere in the individual zones becomes.

Further, in accordance with the invention are preferably used belt calciner according to a preferred embodiment of the method according to the invention, the gas stream, preferably the flow of the inert gas l _2, performed in a single pass by the retaining zone, further preferably, the gas flow from top to bottom, is guided by the holding zone.

Therefore, the present invention relates to the method as described above, wherein at least the inert gas \ ^ _\ is guided in a straight passage through the heating zone, the inert gas \ ^ _\ preferably in a single pass through the heating zone and the inert gas l ₂ in a single pass by the retaining zone be guided. The gas stream, preferably the stream of inert gas which is discharged from the heating zone after the straight pass through the heating zone, and preferably also the gas stream, preferably the stream of the inert gas l ₂ , which is discharged from the holding zone after the straight passage through the holding zone , may be supplied separately from each other or suitably combined to a suitable use. It is possible

For example, the gas streams suitable to clean and then back in the

use according to the invention. In the context of the process according to the invention, the gas streams are particularly preferably not recycled to the process. For this case, according to which no recirculation takes place, it is preferred to feed the gas streams to a purification stage in which the amines introduced during the calcination into the gas stream are preferably removed from the gas streams. A

Cleaning according to the invention is, for example, an acidic wash

Gas streams, which can be carried out for example in one or more washing columns. As the acidic washing medium, for example, an aqueous sulfuric acid solution can be used. Therefore, the present invention also relates to the process as described above, wherein at least the inert gas \ ^ _\, preferably the inert gases \ ^ _\ and l ₂ is not in the heating zone and / or the retaining zone of the Bandkalzinierers be recycled.

Therefore, the present invention also relates to the method as described above, wherein the ribbon calciner comprises:

(i) exactly one heating zone with a device for introducing a gas flow into the heating zone and a device for removing the gas flow from the heating zone;

(ii) exactly one stop zone immediately adjacent to the heating zone, with a device for introducing a gas stream into the holding zone and a device for

Discharge of the gas stream from the holding zone; and

(iii) optionally exactly one immediately following to the holding zone cooling zone with a device for supplying a gas stream in the cooling zone and a

Apparatus for discharging the gas flow from the cooling zone;

the ribbon calciner having no means for circulating the gas stream introduced into the heating zone in the heating zone and no means for circulating the gas stream introduced into the holding zone in the holding zone, and wherein the belt calciner does not provide means for returning the gas streams discharged from the heating zone and from the holding zone having.

Likewise, the present invention also relates to a belt calciner for use in a process for the preparation of a catalyst for the oxidation of ethene

Ethylene oxide, comprising

(I) exactly one heating zone with a device for introducing a gas stream in the heating zone and a device for discharging the gas stream from the

heating zone; (ii) precisely one holding zone immediately following the heating zone, with a device for introducing a gas stream into the holding zone and a device for removing the gas stream from the holding zone; and

Apparatus for discharging the gas flow from the cooling zone;

In the context of the present invention, the belt calciner can be configured such that at least the housing surrounding the heating zone is designed to be heatable. It is also possible that the housing surrounding the heating zone can be heated to a temperature which is sufficient to not negatively influence the inventively high heating rate according to step b). It is further possible that the housing surrounding the heating zone to a temperature T-i, as described above, in particular preferably to a temperature T-i in the range 250 to 295 ° C, is heatable.

In the context of the present invention, the belt calciner can be further configured such that the housing surrounding the holding zone is designed to be heatable. It is also possible that the housing surrounding the holding zone can be heated to a temperature which is sufficient to not negatively influence the holding temperature T _{2 used} according to the invention in accordance with step c). It is further possible that the housing surrounding the holding zone can be heated to a temperature T ₂ , as described above, particularly preferably to a temperature T ₂ in the range Ti to 1, 05 Ti.

According to a preferred embodiment of the present invention is the

Band calciner designed so that a zone directly surrounding housing is designed not heated. In this case, it is particularly preferred to provide a housing which encloses the individual, the heating zone and the holding zone directly surrounding housing, said surrounding housing is designed to be heated. In this case, it is further preferred to carry out the calcination according to the invention in such a way that the housing is suitably heated while the calcination is running and has a temperature of at least 130 ° C. As far as the individual housings surrounding the heating zone and the holding zone are concerned, it is preferred to thermally adequately isolate them. As described above, it is preferable in the invention that the introduced into the heating zone gas, in particular the inert gas \ ^ _\, is heated prior to insertion in an appropriate manner. As described above, it is further preferred according to the invention that the in the gas introduced the holding zone, in particular preferably the inert gas l ₂ , is heated in a suitable manner prior to introduction.

As described further above, in step a) the carrier is provided at a temperature T ₀ , wherein the temperature T _{0 is} preferably in the range of 5 to 20 ° C, more preferably in the range of 5 to 15 ° C. Within the scope of the preferred embodiment of the

According to the method of the present invention, according to which the ribbon calciner as described above is used, it is particularly preferable to supply the carrier to be calcined to the heating zone via a coolable feeder. For example, a coolable gutter or a coolable conveyor belt is preferred. This coolable supply device is preferably cooled to the temperature T ₀ .

In the context of providing according to a) it may be necessary that the carrier obtained after the impregnation is not immediately supplied to the heating according to b), but is stored for a certain time. In this case, it is preferable to store the carrier cooled after impregnation for this time, the preferred temperature at which the impregnated carrier is stored being preferably in the range of 5 to 20 ° C, more preferably in the range of 5 to 15 ° C is. The carrier stored in such a cooled manner is preferably supplied to the heating according to b) via the cooled feed device described above.

According to the invention, it has also been found that the support to be heated to the temperature Ti and preferably to be held at the temperature T ₂ in the strip calciner preferably used according to the invention is preferably guided on the strip passing through the strip calciner substantially monolayer through the strip calciner. By suitable measure, therefore, it is preferably ensured according to the invention that substantially only a single layer of the carrier is present on the belt of the belt calciner, ie the carrier shaped bodies are not adjacent to one another, but substantially adjacent to one another.

As regards the ribbon calciner per se, according to the invention, the embodiments described below and the combinations of embodiments resulting from the back covers described below are particularly preferred: 1. A belt calciner, especially for use in a process for the preparation of a catalyst for the oxidation of ethene to ethylene oxide

(ii) precisely one holding zone immediately following the heating zone, with a device for introducing a gas stream into the holding zone and a device for removing the gas stream from the holding zone; and (iii) optionally exactly one immediately adjacent to the holding zone

Cooling zone with a device for supplying a gas stream in the

Cooling zone and a device for discharging the gas stream from the cooling zone;

A ribbon calciner according to Embodiment 1, comprising a housing surrounding the heating zone, a housing surrounding the holding zone, and both the housing

Heating housing surrounding housing as well as the housing surrounding the holding zone surrounding housing, wherein both the housing surrounding the heating zone and the housing surrounding the holding zone housing heatable, preferably electrically heatable, is.

Bandkalzinierer according to embodiment 2, wherein the both surrounding the heating zone housing and surrounding the holding zone housing surrounding housing to a temperature of at least 130 ° C heatable, preferably electrically heatable, is.

A ribbon calciner according to one of embodiments 1 to 3, comprising a device upstream of the heating zone for heating the gas stream to be introduced into the heating zone, preferably for heating the gas stream to be introduced into the heating zone to a temperature in the range from Ti to 1.1 Ti, more preferably in the range from Ti to 1, 07 Ti, more preferably in the range of Ti to 1, 05

A belt calciner according to any one of embodiments 1 to 4, comprising a device preceding the holding zone for heating the device into the holding zone

to be introduced gas stream, preferably for heating the in the holding zone

gas stream to be introduced to a temperature in the range of T ₂ to 1, 1 T ₂ , more preferably in the range of T ₂ to 1, 07 T ₂ , more preferably in the range of T ₂ to 1, 05 T ₂ such as in the range of T. ₂ to 1, 04 T ₂ or in the range of T ₂ to 1, 03 T ₂ or in the range of T ₂ to 1, 02 T ₂ or in the range of T ₂ to 1, 01 T ₂ .

A belt calciner according to any one of embodiments 1 to 5, comprising a supply device, which can be cooled to a temperature T ₀ in the range of 5 to 20 ° C, for feeding the catalyst to be calcined into the heating zone. 7. The belt calciner according to any one of embodiments 1 to 6, comprising a to a temperature T ₀ in the range of 5 to 20 ° C cooled storage device for the cooled storage of the catalyst to be calcined. 8. The belt calciner according to embodiment 7, wherein the supply device according to

Claim 6 is suitably connected to the storage device according to claim 7 for receiving the stored carrier.

9. Use of a Bandkalzinieres according to one of claims 1 to 8 in one

Process for preparing a catalyst for the oxidation of ethene

Ethylene oxide.

Surprisingly, it has been found that the carrier heated with the high heating rate according to the invention in the belt calciner as described above in step a), in particular in the belt calciner described above in the manner described above

Inertgasatmosphäre heated carrier, having advantageous properties as a catalyst in the oxidation of ethene to ethylene oxide.

Fixed bed reactor in the presence of this catalyst.

Process for the preparation of ethylene oxide

According to the invention, the oxidation of ethene to ethylene oxide can be carried out by all methods known to the person skilled in the art. Any of the reactors usable in the ethylene oxide production processes of the prior art may be used, for example, externally cooled shell and tube reactors or bulk catalyst reactors

Cooling tubes. The oxidation preferably takes place in a tube reactor, preferably in a tube bundle reactor. As far as the reaction conditions are concerned, it is possible, for example, to refer to this

Disclosure in DE 25 21 906 A1, EP 0 014 457 A2, DE 2 300 512 A1, EP 0 172 565 A2, DE 24 54 972 A1, EP 0 357 293 A1, EP 0 266 015 A1, EP 0 085 237 A1, EP 0 082 609 A1 and EP 0 339 748 A2. In principle, inert gas such as nitrogen or inert gases such as water vapor, methane and optionally reaction moderators such as halides, hydrocarbons such as ethyl chloride, vinyl chloride or 1, 2-dichloroethane can additionally be mixed with the reaction gas containing ethane and oxygen. Conveniently, the oxygen content in the reactor is in a range such that no explosive gas mixture is present.

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 of ethene are, for example, "polymer grade" ethene, which typically has a purity of at least 99%, or "chemical grade" ethene, which typically has a purity of 95% or less. The impurities typically consist mainly of ethane, propane and / or propene.

The oxidation of ethene to ethylene oxide is usually carried out at elevated temperature. Preferred are temperatures in the range of 150 to 350 ° C, more preferably in the range of 180 to 300 ° C, more preferably temperatures in the range of 190 ° C to 280 ° C, and most preferably temperatures in the range of 200 ° C to 280 ° C.

The oxidation of ethene to ethylene oxide is preferably carried out at pressures in the range from 5 to 30 bar. More preferably, the oxidation takes place at a pressure in the range of 5 bar to 25 bar, more 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.

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

Size / average area of the reactor, the shape and the size of the catalyst preferably in the range of 800 / h to 10,000 / h, preferably in the range of 2000 / n to 6000 / h, more preferably in the range of 2500 / h to 5000 / h, in each case based on the volume of the catalyst bed in the reactor.

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 stream, which after supplementing with the required amounts of, for example, ethene, oxygen and / or Reaktionsmoderatoren back in the reactor is introduced.

The separation of the ethylene oxide from the product stream and the optionally subsequent work-up can be carried out according to customary processes of the prior art (cf., Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A-10, pages 1 17-135, in particular 123-125, VCH Verlagsgesellschaft, Weinheim 1987). Preferred processes and catalysts according to the invention are described in the following embodiments 1 to 22 and the combinations of embodiments resulting from the respective back references. As for preferred embodiments relating to the configuration of the band calcinating described below, reference is made to the preferred embodiments 1 to 8 described above, which are included in the context of the preferred embodiments 1 to 22 described below and are therefore to be read.

1 . Process for preparing a catalyst for the oxidation of ethene

Ethylene oxide, comprising

2. Process according to embodiment 1, wherein the heating rate is in the range of 30 to 80 K / min, preferably in the range of 40 to 75 K / min.

3. The method according to embodiment 1 or 2, wherein the temperature T ₀ in the range of 5 to 20 ° C, preferably in the range of 10 to 15 ° C, is located.

4. The method according to any one of embodiments 1 to 3, wherein the temperature T-i im

Range of 250 to 295 ° C, preferably in the range of 270 to 290 ° C, is located

5. The method according to any one of embodiments 1 to 4, wherein the heating according to b) by contacting the carrier with an inert gas \ ^ _\ , preferably with nitrogen, takes place, with \ ^ _\ preferably less than 10 ppm, more preferably from 5 to 9 ppm, contains oxygen.

6. The method according to embodiment 5, wherein \ ^ _{\ has} a temperature in the range of Ti to 1, 1 Ti.

7. The method according to any one of embodiments 1 to 6, further comprising

c) holding the carrier heated to the temperature Ti at a temperature T ₂ , wherein T _{2 is} preferably in the range of 0.90 Ti to 1, 1 Ti.

8. The method according to embodiment 7, wherein the holding according to c) by means of a

Inertgases l ₂ , preferably by means of nitrogen, is carried out, wherein the inert gas l ₂ preferably less than 10 ppm, more preferably from 5 to 9 ppm oxygen, and wherein the inert gas is preferably a temperature in the range of T ₂ to 1, 05 T ₂ having. 9. The method according to embodiment 7 or 8, wherein in c) the support is maintained at the temperature T ₂ for a time in the range of 1 to 15 minutes, preferably from 2 to 10 minutes, more preferably from 3 to 5 minutes. 10. The method according to any one of embodiments 1 to 9, further comprising

1 1. Process according to embodiment 10, wherein the cooling according to d) in a

Atmosphere containing at least 5% by volume, preferably at least 15% by volume

Oxygen, more preferably in air, takes place.

12. The method according to any one of embodiments 1 to 1 1, wherein at least the heating according to b) is carried out in a belt calciner.

13. The method of embodiment 12, wherein the belt calciner exactly one

Comprises heating zone, wherein in the heating zone of the invention) to be heated carrier of an inert gas \ ^ _\, is preferably flows of nitrogen b, where \ ^ _\ preferably less than 10 ppm more preferably contains of from 5 to 9 ppm, oxygen, \ ^ _\ preferably has a temperature in the range of Ti to 1, 1 Ti, and wherein \ ^ _\ the

Carrier preferably with a flow rate in the range of 2500 to 5000 m ³ / h, more preferably from 3200 to 4500 m ³ / h, flows through.

14. The method of embodiment 12 or 13, wherein the Bandkalzinierer has exactly one, following the heating zone holding zone, wherein in the holding zone holding the heated to the temperature Ti carrier at a temperature T ₂ , and wherein in the holding zone of the at An inert gas l ₂ , preferably of nitrogen, flows through the temperature T ₂ , wherein l ₂ preferably contains less than 10 ppm, more preferably from 5 to 9 ppm, oxygen, where l _{2 is} preferably a

Temperature T ₂ , and wherein l ₂ preferably flows through the carrier with a volume flow in the range of 1000 to 3000 m ³ / h, more preferably from 1500 to 2000 m ³ / h.

Method according to embodiment 14, wherein the belt calciner has a cooling zone following the holding zone and in the cooling zone a cooling of the carrier held at the temperature T ₂ to a temperature T ₃ , preferably at most 60 ° C., takes place.

A method according to any one of embodiments 14 or 15, wherein at least the inert gas \ ^ _\ is guided in a straight passage through the heating zone, the inert gas \ ^ _\ preferably be performed ₂ in a straight passage through the holding zone in a single pass through the heating zone and the inert gas l , 17. The method according to any of embodiments 14 to 16, wherein at least the inert gas, preferably the inert gases \ ^ _\ l and _2, are not recycled to the heating zone and / or the retaining zone of the Bandkalzinierers.

18. The method according to any one of embodiments 1 to 17, wherein according to a) of

Alumina-containing supports additionally with rhenium or with a rhenium-containing compound, preferably further additionally with tungsten or with a tungsten-containing compound and / or with lithium or with a lithium-containing compound and / or with cesium or with a cesium-containing

A compound is impregnated, and wherein the carrier is optionally impregnated with sulfur or with a sulfur-containing compound.

19. The method of embodiment 18, wherein according to a) the aqueous solution containing a silver-containing compound additionally comprises a rhenium-containing compound, preferably further additionally a tungsten-containing compound and / or a lithium-containing compound and / or a cesium-containing compound and optionally a sulfur-containing compound. 20. The method according to any one of embodiments 1 to 19, wherein the according to a)

provided, alumina-containing carrier cylinder geometry, wherein the cylinder preferably has a length in the range of 5 to 10 mm, a

Outside diameter in the range of 5 to 10 mm and a ratio of

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

21. Catalyst for the oxidation of ethene to ethylene oxide, obtainable after one

Method according to one of the embodiments 1 to 20.

22. A process for producing ethylene oxide by gas phase oxidation of ethene

by means of molecular oxygen in a fixed bed reactor in the presence of a

Catalyst according to embodiment 21.

The present invention is illustrated by the following examples and comparative examples: Examples

Reference Example 1: Preparation of an impregnated carrier

1.1 Table 1a:

Chemical and physical properties of the alumina support used according to the invention (Examples 1 to 5) with bimodal pore distribution

Table 1 b:

Chemical and physical properties of the alumina support used according to the invention (Example 6) with bimodal pore distribution

1 .2 Preparation of the silver complex solution

It was submitted to 1, 5 L of deionized water (demineralised water = demineralized water) and added with stirring 550 g of silver nitrate and completely dissolved therein. The solution was heated to 40.degree. 402.62 g of potassium hydroxide solution (47.8%) were mixed with 1.2 L of deionized 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 stirred 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 conductivity measurement of the washing solution, potassium or nitrate-free in the present case means conductivity The water was removed as completely as possible from the filter cake and the residual moisture of the filter cake was determined to give 620 g of silver oxalate having a water content of 20.80%. Cool 10 ° C. and add small portions of water (245 g) .After the addition of water, 484.7 g of the (still moist) silver oxalate obtained were added in small portions over about 30 minutes .The mixture was stirred overnight at room temperature and the residue From the remaining clear solution, the Ag content was determined by refractometry and the density was determined using a 10 mL graduated cylinder ,

The resulting solution received 29.14% by weight of silver, calculated as element, and had a density of 1.532 g / mL.

1 .3 General preparation of the solution containing silver and promoters

97.1004 g of the silver complex solution were submitted. To 1 1047 were an aqueous solution of lithium and sulfur (2.85 wt .-% lithium from lithium nitrate and 0.21 wt .-% sulfur from ammonium _sulfate), 1, 791 g of an aqueous solution of tungsten and cesium (2 wt % Tungsten from tungstic acid and 3.5% by weight cesium from cesium hydroxide 50% in H ₂ O) and 1.6492 g of an aqueous solution of rhenium (3.1% by weight of

Ammonium perrhenate) and the solution stirred for 5 min. 1 .4 General procedure for applying the solution to the support

140.61 g of the support (see Table 1) were placed in a rotary evaporator and evacuated. The vacuum was 20 mbar. The carrier was pre-evacuated for about 10 min.

The solution obtained according to procedure 1.3 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. 1 .5 General preparation of catalyst split

The resulting catalyst rings were coarsely crushed in a porcelain dish with the mortar. Subsequently, the comminuted material was brought to the desired particle size fraction (500-900 μm) by means of a screening machine, round sieve and balls. Very hard rings were completely crushed with the mortar and then sieved.

1 .6 General procedure for testing catalysts (epoxidation of ethylene)

The epoxidation was carried out in a test reactor consisting of a vertical stainless steel reaction tube having an inner diameter of 6 mm and a length of 2200 mm. The jacketed reaction tube was heated with hot oil of temperature T (oil) 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 heated from bottom to top at a height of 212 mm with inert steatite spheres (1, 0-1, 6 mm), above at a height of 1100 mm with 38.2 g of catalyst chippings, particle size 0.5-0.9 mm, and above at a height of 707 mm with inert steatite balls (1, 0-1, 6 mm) filled. 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% by volume of ethylene, 7% by volume of oxygen, 1% by volume of CO ₂ . At the beginning, 2.5 ppm of EC (ethylene chloride) was used for startup. Depending on the catalyst and performance, the EC concentration was increased every 24 hours to a maximum of 8 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 (ethylene oxide) / (m ³ (Kat) xh). The reaction temperature was controlled according to the specified ethylene oxide exhaust gas concentration of 2.7%. In order to optimize the catalyst in terms of selectivity and conversion, between 2.2 and 8.0 ppm of ethylene chloride were 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.

Example 1 (According to the Invention) 360.1 g of the support according to Table 1 a (see above 1 .1) were treated in accordance with general instructions 1.4 with 237.3 g of the impregnation solution. The

Vacuum cold water uptake of the alumina carrier was used to calculate the quantities required for the preparation according to 1.4. The following quantities were used in the preparation of the solution according to general rule 1 .4: 226.97 g silver complex solution (29.14% Ag, density 1, 528 g / ml)

2.8446 g of a solution containing 2.85% lithium and 0.21% sulfur _,

4.2669 g of a solution containing 2.00% tungsten and 3.5% cesium,

3.2262 g of a 4.1% rhenium solution.

130 g of the moist catalyst, obtained according to general procedure 1.4, were then calcined under the following conditions: oven temperature 283 ° C.,

Nitrogen flow 8.3 m ³ / h, heating rate 32 K / min, heating time 450 s to 265 ° C.

Catalyst internal temperature, holding time at 265 ° C 390 s, cooling to room temperature within 420 s. The resulting catalyst was then tested according to General Procedure 1 .6. The result is shown in Table 2.

Example 2 (According to the Invention) 100.1 g of the support according to Table 1 a (see above 1 .1) were treated in accordance with general procedure 1.4 with 65.89 g of the impregnation solution. The

Vacuum cold water uptake of the alumina carrier was used to calculate the quantities required for the preparation according to 1.4. The following quantities were used in the preparation of the solution according to general rule 1 .4:

62.64 g silver complex solution (29.35% Ag, density 1, 532 g / ml)

0.7907 g of a solution containing 2.85% lithium and 0.21% sulfur _,

1.1861 g of a solution containing 2.00% tungsten and 3.5% cesium,

0.8968 g of a solution containing 4.1% rhenium,

0.3830 g of water.

100 g of the moist catalyst obtained according to general procedure 1.4 were then calcined under the following conditions: oven temperature 283 ° C,

Nitrogen flow 8.3 m ³ / h, heating rate 40 K / min, heating time 360 s to 266 ° C.

Catalyst internal temperature, holding time at 266 ° C 360 s, cooling to room temperature within 420 s. The resulting catalyst was then tested according to General Procedure 1 .6. The result is shown in Table 2.

Example 3 (according to the invention)

330 g of the carrier according to Table 1 a (see above 1 .1) were treated according to general procedure 1.4 with 217.4 g of the impregnation solution. The vacuum cold water absorption of the alumina support was used to calculate the quantities required for the preparation according to 1 .4. The following quantities were used in the preparation of the solution according to general rule 1 .4:

205.1 g silver complex solution (29.35% Ag, density 1, 539 g / ml)

2.6041 g of a solution containing 2.85% lithium and 0.21% sulfur _,

3.9061 g of a solution containing 2.00% tungsten and 3.5% cesium,

3.9061 g of a solution containing 3.1% rhenium,

1, 8545 g of water. 63.9 g of the moist catalyst obtained according to general procedure 1 .4 were then calcined under the following conditions. Oven temperature 283 ° C,

Nitrogen flow 8.3 m ³ / h, heating rate 67 K / min, heating time 185 s to 260 ° C.

Catalyst internal temperature, hold at 262 ° C 415 s, cool to room temperature within 420 s. The resulting catalyst was then tested according to General Procedure 1 .6. The result is shown in Table 2.

Example 4 (Comparative Example)

350.1 g of the carrier according to Table 1 a (see above 1 .1) were treated in accordance with general procedure 1.4 with 230.5 g of the impregnation solution. The

Vacuum cold water uptake of the alumina carrier was used to calculate the quantities required for the preparation according to 1.4.

The following quantities were used in the preparation of the solution according to general rule 1 .4:

219.08 g silver complex solution (29.35% Ag, density 1, 532 g / ml)

2.7656 g of a solution containing 2.85% lithium and 0.21% sulfur _,

4.1484 g of a solution containing 2.00% tungsten and 3.5% cesium,

3.1366 g of a 4.1% rhenium solution,

1, 3397 g of water.

350 g of the moist catalyst obtained according to general procedure 1.4 were then calcined under the following conditions. Oven temperature 283 ° C,

Nitrogen flow 8.3 m ³ / h, heating rate 19 K / min, heating time 780 s to 266 ° C.

Catalyst internal temperature, hold at 266 ° C 720 s, cool to room temperature within 420 s. The resulting catalyst was then tested according to General Procedure 1 .6. The result is shown in Table 2. Example 5 (Comparative Example) 360.1 g of the carrier according to Table 1 a (see above 1 .1) were treated in accordance with general procedure 1.4 with 237.3 g of the impregnation solution. The

226.97 g silver complex solution (29.14% Ag, density 1, 528 g / ml)

2.8446 g of a solution containing 2.85% lithium and 0.21% sulfur _,

4.2669 g of a solution containing 2.00% tungsten and 3.5% cesium,

3.2262 g of a 4.1% rhenium solution.

160 g of the moist catalyst obtained according to general procedure 1 .4 were then calcined under the following conditions. Oven temperature 283 ° C,

Nitrogen flow 8.3 m ³ / h, heating rate 28 K / min, heating time 510 s to 264 ° C.

Catalyst internal temperature, holding time at 264 ° C 330 s, cooling to room temperature within 420 s. The resulting catalyst was then tested according to General Procedure 1 .6. The result is shown in Table 2.

Example 6 (comparative example)

400 g of the carrier according to Table 1 b (see above 1 .1) were treated according to general procedure 1.4 with 281, 36 g of the impregnation solution. The vacuum cold water absorption of the alumina carrier is used to calculate the quantities required for the preparation according to 1.4.

253.96 g silver complex solution (29.35% Ag, density 1, 532 g / ml)

3.1600 g of a solution containing 2.85% lithium and 0.21% sulfur _,

4.7400 g of a solution containing 2.00% tungsten and 4.0% cesium,

4.7400 g of a solution containing 3.1% rhenium,

14.7881 g of water.

400 g of the moist catalyst obtained according to general procedure 1 .4 were then calcined under the following conditions. Oven temperature 289 ° C,

Nitrogen flow 1, 0 m ³ / h, heating rate 26 K / min, heating time 600 s to 289 ° C

Catalyst internal temperature, holding time at 280 ° C 1800 s, cooling to room temperature within 420 s. The resulting catalyst was then tested according to General Procedure 1.6. The result is shown in Table 2. Results:

Composition of the catalysts according to Example 1 to 5:

The catalysts contained 15.5% Ag, 190 ppm Li, 14 ppm S, 200 ppm W, 350 ppm Cs, 310 ppm Re, and were varied as indicated in the examples

Heating rates calcined. It has been shown that calcination with heating rates of at least 30 K / min has a positive effect on the selectivity and activity of the silver catalyst. Compared to the catalysts, which were calcined with smaller heating rates, an improved selectivity of up to 2.6% with an improved activity of 7 ° C could be detected. At too low heating rates, significant drops in performance were visible (Examples 4 and 5 (Comparative Examples)).

Table 2

Performance results of the investigated catalysts

Claims

claims

1 . Process for preparing a catalyst for the oxidation of ethene

Ethylene oxide, comprising

2. The method of claim 1, wherein the heating rate in the range of 30 to 80 K / min, preferably in the range of 40 to 75 K / min, is located.

3. The method of claim 1 or 2, wherein the temperature T ₀ in the range of 5 to 20 ° C, preferably in the range of 10 to 15 ° C, is located.

4. The method according to any one of claims 1 to 3, wherein the temperature Ti in the range of 250 to 295 ° C, preferably in the range of 270 to 290 ° C, is located

5. The method according to any one of claims 1 to 4, wherein the heating according to b) by contacting the carrier with an inert gas \ ^ _\ , preferably with nitrogen, is carried out, wherein preferably less than 10 ppm, more preferably from 5 to 9 ppm oxygen ,

6. The method of claim 5, wherein \ ^ _{\ has} a temperature in the range of Ti to 1, 1 Ti.

7. The method according to any one of claims 1 to 6, further comprising

8. The method according to claim 7, wherein the holding according to c) by means of an inert gas l ₂ , preferably by means of nitrogen, takes place, wherein the inert gas l ₂ preferably less than 10 ppm, more preferably from 5 to 9 ppm oxygen, and wherein the inert gas preferably has a temperature in the range of T ₂ to 1, 05 T ₂ .

9. The method according to claim 7 or 8, wherein in c) the carrier at the temperature T ₂ for a time in the range of 1 to 15 minutes, preferably from 2 to 10 minutes, more preferably from 3 to 5 minutes is maintained.

10. The method according to any one of claims 1 to 9, further comprising d) cooling the held at the temperature T ₂ carrier to a temperature T ₃ , wherein T _{3 is} at most 60 ° C.

1 1. Process according to claim 10, wherein the cooling according to d) takes place in an atmosphere containing at least 5% by volume, preferably at least 15% by volume of oxygen, more preferably under air.

12. The method according to any one of claims 1 to 1 1, wherein according to a) the alumina-containing carrier additionally with rhenium or with a rhenium-containing compound, preferably further additionally with tungsten or with a tungsten

containing compound and / or with lithium or with a lithium-containing compound and / or with cesium or with a cesium-containing compound, and wherein the carrier is optionally impregnated with sulfur or with a sulfur-containing compound.

13. The method according to claim 12, wherein according to a) the aqueous solution containing a silver-containing compound additionally comprises a rhenium-containing compound, preferably further additionally a tungsten-containing compound and / or a lithium-containing compound and / or a cesium-containing compound and optionally a sulfur-containing compound.

14. The method according to any one of claims 1 to 13, wherein the provided according to a) alumina-containing carrier cylinder geometry, wherein the cylinder preferably has a length in the range of 5 to 10 mm, an outer diameter in the range of 5 to 10 mm and a ratio from outside diameter / mm to

Wall thickness / mm in the range of 2.5 to 4.5.

15. Catalyst for the oxidation of ethene to ethylene oxide, obtainable after one

Method according to one of claims 1 to 14.

16. A process for producing ethylene oxide by gas phase oxidation of ethene

by means of molecular oxygen in a fixed bed reactor in the presence of a

Catalyst according to claim 15.