JP2015518421A - Catalyst for alkene epoxidation - Google Patents

Abstract

The present invention relates to a catalyst for preparing alkylene oxide, a supported silver catalyst having a novel promoter combination. The invention further relates to a process for producing the catalyst and the use of the catalyst to oxidize alkylene to alkylene oxide. Furthermore, the present invention relates to a process for preparing ethylene oxide from ethylene comprising the step of oxidizing ethylene in the presence of the mentioned catalyst.

Description

  The present invention relates to a catalyst for preparing alkylene oxide, a supported silver catalyst having a novel promoter combination. The invention further relates to a process for producing the catalyst and the use of the catalyst to oxidize alkylene to alkylene oxide. Furthermore, the invention relates to a process for preparing ethylene oxide from ethylene comprising the step of oxidizing ethylene in the presence of the mentioned catalyst.

  Ethylene oxide is an important basic chemical and is prepared on the industrial scale by direct oxidation of ethylene using oxygen, often in the presence of a catalyst containing silver. Supported catalysts are often used in which catalytically active metallic silver is applied to the support using a suitable method. As a support, it is possible in principle to use various porous materials such as activated carbon, titanium dioxide, zirconium dioxide or silicon dioxide, or ceramic compositions, or mixtures of these materials. In general, alpha aluminum oxide is used as the support.

  Apart from silver as the active ingredient, these catalysts usually contain promoters for improving the catalyst properties (WO 2007/122090, WO 2010/123856). Examples of promoters include alkali metal compounds and / or alkaline earth metal compounds. Several documents teach the use of transition metals such as cobalt (EP 0480538), tungsten or molybdenum. A particularly preferred promoter for affecting catalyst activity and selectivity is rhenium. In the industry, due to its high selectivity, preference is given to using catalysts containing rhenium and / or other transition metal promoters in combination with alkali metal compounds and / or alkaline earth metal compounds. Selectivity is, for example, in the case of ethylene oxidation, the mole% of ethylene that reacts to form ethylene oxide. The activity of the catalyst is otherwise characterized by the ethylene oxide concentration at the reactor outlet under certain conditions, such as temperature, pressure, gas throughput, amount of catalyst, etc. The higher the ethylene oxide concentration in the reactor output stream, the higher the activity of the catalyst. The lower the temperature required to achieve a particular ethylene oxide concentration, the higher the activity. In order to achieve high selectivity, the combination of active metal and promoter and the composition of the support are usually matched to each other in order to obtain a catalyst having very good properties.

  Direct oxidation of ethylene to ethylene oxide using a supported silver catalyst includes, for example, German Offenlegungsschrift 2300512; German Offenlegungsschrift 2521906; European Patent Publication No. 0014457; Patent No. 2454972, European Patent Application Publication No. 0172565, European Patent Application Publication No. 0357293, European Patent Application Publication No. 0266015, European Patent Application Publication No. 0011356, European Patent Application This is described in Japanese Patent Publication No. 0085237, German Patent Publication No. 2560684 and German Patent Publication No. 2753359.

International Publication No. 2007/122090 Pamphlet International Publication No. 2010/123856 Pamphlet European Patent No. 0480538 German Published Patent No. 2300512 German Published Patent No. 2521906 European Patent Application Publication No. 0014457 German Published Patent No. 2454972 European Patent Application No. 0172565 European Patent Application No. 0357293 European Patent Application No. 0266015 European Patent Application Publication No. 0011356 European Patent Application Publication No. 0085237 German Published Patent No. 2560684 Specification German Published Patent No. 2753359

  It is an object of the present invention to provide novel catalysts for alkene epoxidation that exhibit advantageous activity and / or selectivity.

  Therefore, the present inventors have found a novel catalyst in which molybdenum and tin elements instead of silver and tungsten are applied to the support as promoters.

  Accordingly, the present invention provides a tungsten free catalyst for alkene epoxidation comprising silver, molybdenum and tin applied to a support.

  The catalyst of the present invention includes a support. Supports suitable for the purposes of the invention can be produced by methods known from the prior art. Examples include US 2009/0198076, WO 2006/133187, WO 03/072444, US 2005/0096219 and European Patent 0496386. There are methods described in the specification.

  Examples of suitable support materials include aluminum oxide, silicon dioxide, silicon carbide, titanium dioxide, zirconium dioxide and mixtures thereof, with aluminum oxide being preferred. Accordingly, in a preferred embodiment, the present invention provides a catalyst wherein the support is an aluminum oxide support.

  The term aluminum oxide as used herein includes all possible structures such as α, γ or θ aluminum oxide. In a preferred embodiment, the support is an alpha aluminum oxide support. Accordingly, the present invention also provides a catalyst in which the support is alpha aluminum oxide.

  In a further preferred embodiment, the alpha aluminum oxide is at least 75% pure, preferably at least 80% pure, more preferably at least 85% pure, more preferably at least 90% pure, more preferably at least 98% pure. More preferably at least 98.5% purity, particularly preferably at least 99% purity.

  Thus, the term alpha aluminum oxide also includes additional components such as zirconium, alkali metals, alkaline earth metals, silicon, zinc, gallium, hafnium, boron, fluorine, copper, nickel, manganese, iron, cerium, titanium, Also included are elements selected from the group consisting of chromium and compounds of these elements, and mixtures of two or more of these elements and / or alpha aluminum oxide containing compounds thereof.

  In general, catalyst supports suitable for the purposes of the present invention are prepared by mixing aluminum oxide with water or another suitable liquid, and a burnout material or pore former, and at least one binder. can do. Suitable pore formers are, for example, cellulose and cellulose derivatives (such as methylcellulose, ethylcellulose, carboxymethylcellulose) or polyolefins (such as polyethylene and polypropylene) or natural incineration materials (such as walnut shell grinds). The pore former is selected to burn out completely from the aluminum oxide at the furnace temperature selected for calcination to form the finished alpha aluminum oxide support. Suitable binders or extrusion aids are described, for example, in EP 0496386. By way of example, mention may be made of aluminum oxide gels comprising nitric acid or acetic acid, cellulose, for example methylcellulose, ethylcellulose or carboxyethylcellulose, or methyl stearate or ethyl stearate, polyolefin oxide, waxes and similar substances.

  The paste formed by mixing can be formed into a desired shape by extrusion. Extrusion aids can be used to assist in the extrusion process.

  The molded body obtained as described above is usually dried and fired after molding to obtain an aluminum oxide carrier. Firing is usually performed at a temperature in the range of 1200 ° C to 1600 ° C. It is usual to wash the aluminum oxide support after calcination in order to remove soluble constituents.

  The alpha aluminum oxide can comprise further components in any suitable form, for example as an element and / or in the form of one or more compounds. When alpha aluminum oxide includes one or more components in the form of a compound, alpha aluminum oxide includes these, for example, as oxides or mixed oxides. Thus, suitable carriers for the purposes of the present invention are also from the group consisting of silicon dioxide, sodium oxide, potassium oxide, calcium oxide and magnesium oxide, nickel oxide, gallium oxide, hafnium oxide, copper oxide, iron oxide and mixtures thereof. Also included is alpha aluminum oxide containing at least one additional component selected.

  With respect to the amount of further components, the total amount of further components is preferably less than 25% by weight, more preferably less than 20% by weight, more preferably less than 15% by weight, more preferably 10% by weight, based on the total weight of the support. Less than, more preferably less than 5% by weight, more preferably less than 2% by weight, more preferably less than 1.5% by weight, particularly preferably less than 1% by weight.

  When the support comprises, for example, an alkali metal, the support is preferably a total amount in the range of 10 to 2500 ppm, more preferably an amount of 10 to 1000 ppm, more preferably 50 to 50, calculated on the basis of the total weight of the support and as an element. Contains alkali metal in an amount of 850 ppm. In one embodiment, the support comprises at least one alkali metal selected from the group consisting of sodium and potassium. When the carrier comprises, for example, sodium, the carrier is preferably in an amount in the range of 10 to 1500 ppm, more preferably 10 to 800 ppm, more preferably 10 to 500 ppm, calculated on the total weight of the carrier and as an element. Containing sodium. If the support comprises, for example, potassium, the support is preferably in an amount in the range of 10 to 1000 ppm, more preferably in an amount of 10 to 500 ppm, more preferably 10 to 300 ppm, calculated as an element, based on the total weight of the support. In the amount of potassium. In one embodiment of the invention, the support comprises, for example, sodium in an amount of 10-1500 ppm and potassium in an amount of 10-1000 ppm.

  Thus, the present invention also provides that the support is in an amount of 10 to 1500 ppm sodium and an amount of 10 to 1000 ppm potassium, particularly preferably an amount of 10 to 500 ppm, calculated on the total weight of the support and in each case as an element. Also described is a catalyst comprising sodium and potassium in an amount of 10-300 ppm.

  If the support comprises, for example, an alkaline earth metal, the support is preferably a total amount in the range of up to 2500 ppm, for example in the range of 10 to 2500 ppm, more preferably 10 based on the total weight of the support and calculated as an element. An alkaline earth metal in an amount of ˜1200 ppm, more preferably in an amount of 10 to 700 ppm. In one embodiment, the support comprises at least one alkaline earth metal selected from the group consisting of calcium and magnesium. When the carrier comprises, for example, calcium, the carrier is preferably in an amount in the range of 10 to 1500 ppm, more preferably in an amount of 10 to 1000 ppm, more preferably 10 to 500 ppm, calculated as an element, based on the total weight of the carrier. Containing calcium. When the support comprises, for example, magnesium, the support is preferably in an amount in the range of 10-800 ppm, more preferably in an amount of 10-500 ppm, more preferably 10-250 ppm, calculated on the total weight of the support and as an element. In the amount of magnesium.

  Thus, the present invention also describes a catalyst wherein the support comprises an amount of 10 to 800 ppm magnesium and an amount of 10 to 1500 ppm calcium, in each case calculated on the total weight of the support and as an element. The support is particularly preferably, for example, in each case based on the total weight of the support and calculated as an element, in an amount of 10-1500 ppmn of sodium, in an amount of 10-1000 ppm of potassium, and in an amount of 10-800 ppm of magnesium. , And calcium in an amount of 10 to 1500 ppm.

  When the support comprises, for example, silicon, the support is preferably in an amount in the range of 50-10000 ppm, more preferably in the range of 50-5000 ppm, more preferably 50-600 ppm, calculated on the total weight of the support and as an element. In an amount of silicon.

  Preferred supports for the purposes of the present invention are, for example, having a purity of at least 90%, and in total 50 to 10,000 ppm of silicon, calculated as elements in each case and based on the total weight of the support, and 10 to 1500 ppm of It is alpha aluminum oxide containing sodium and 10-2500 ppm of alkaline earth metal. The support preferably contains calcium and / or magnesium as the alkaline earth metal. 50-5000 ppm silicon, 10-800 ppm sodium, 10-700 ppm alkaline earth metal, having a purity of at least 98% by weight, in total, calculated as elements in each case and based on the total weight of the support Particularly preferred is alpha aluminum oxide containing.

The support used in the catalyst of the present invention is preferably 0.1 to 5 m ² / g, more preferably from 0.1~2m ² / g, more preferably of 0.5 to 1.5 m ² / g BET surface area measured according to the method described in standard ISO 9277 in the range, more preferably in the range 0.6 to 1.3 m ² / g, particularly preferably in the range 0.6 to 1.0 m ² / g. Have.

  Furthermore, the support used in the catalyst of the present invention preferably has pores having a diameter in the range of 0.1 to 100 μm, and the pore distribution is monomodal or polymodal, For example, it can be bimodal, trimodal, or tetramodal. The support preferably has a bimodal pore distribution. The carrier is more preferably in the range of 0.1-10 μm and 15-100 μm, preferably in the range of 0.1-5 μm and 17-80 μm, more preferably in the range of 0.1-3 μm and 20-50 μm, more preferably It has a bimodal pore distribution with peak maxima in the range of 0.1-1.5 μm and 20-40 μm. The pore diameter is measured by Hg porosity measurement (described in standard DIN 66133). As used above, the term “bimodal pore distribution with peak maxima in the range of 0.1-10 μm and 15-100 μm” has one of the two peak maxima in the range of 0.1-10 μm; It shows that the other peak maximum is in the range of 15 to 100 μm.

  Thus, the present invention also provides that the support has a bimodal pore distribution, preferably a pore having a pore diameter in the range of 0.1 to 15 μm and a pore diameter in the range of 15 to 100 μm, as measured by Hg porosity measurement. Also described is a catalyst having a bimodal pore distribution comprising pores having

  Although the support geometry is generally less important, the support is advantageously a very large portion of the external surface area where the reaction gas is coated with catalytically active silver particles and optionally further promoters, as well as the internal surface area of the support. It should be in the form of particles that allow it to diffuse unimpeded. The selected geometry of the support should ensure a very small pressure drop across the reactor length. In a preferred embodiment, the carrier is used as a shaped body, for example as an extrudate, hollow extrudate, star extrudate, sphere, ring or hollow ring. The carrier is preferably a shaped body having a hollow body geometry. The following geometry (outer diameter x length x inner diameter, reported in mm for each case): 5 x 5 x 2, 6 x 6 x 3, 7 x 7 x 3, 8 x 8 x 3, 8 x 8.5 × 3, 8 × 8.5 × 3.5, 8.5 × 8 × 3.5, 8.5 × 8 × 3, 9 × 9 × 3, 9.5 × 9 × 3, 9.5 × 9 A cylinder with x3.5 is particularly preferred. Each length shown assumes a tolerance of about ± 0.5 mm.

  According to the invention, it is also possible to use the catalyst in the form of a ground catalyst material obtained from one or more of the shaped bodies mentioned.

  The water absorption of the carrier is, for example, in the range from 0.35 ml / g to 0.65 ml / g, preferably in the range from 0.42 ml / g to 0.52 ml / g, as measured by vacuum cold water uptake.

  The catalyst of the present invention contains silver as an active metal. The catalyst may comprise, for example, silver in an amount of 5 to 35% by weight, in particular 10 to 30% by weight, preferably 10 to 25% by weight, calculated as elements, based on the total weight of the catalyst. The silver is preferably applied to the support in the form of a silver compound which can be a salt or a salt complex. The silver compound is preferably applied as a solution, in particular as an aqueous solution. In order to obtain a soluble form of the silver compound, a complexing agent such as ethanolamine, EDTA, 1,3- or 1,2-propanediamine, ethylenediamine and / or an alkali metal oxalate is used in a suitable manner. For example, it can be added to silver (I) oxide or silver (I) oxalate, and this complexing agent can also act as a reducing agent at the same time. Silver is particularly preferably applied in the form of a silver-amine compound, particularly preferably a silver-ethylenediamine compound.

  Furthermore, the catalyst of the present invention contains at least one of molybdenum and elemental tin as a promoter. For the purposes of the present invention, a promoter may thereby improve one or more catalyst properties, such as selectivity, activity, conversion, yield and / or operating life, relative to a catalyst that does not contain components. The component of the catalyst achieved. Preference is given to compounds that are highly chemically stable under the reaction conditions and do not catalyze any undesirable reactions. The promoters are usually 10 to 3000 ppm total and 5 to 1500 ppm each, more preferably 10 to 1300 ppm each, particularly preferably 50 to 50 ppm each, calculated on the total weight of the catalyst and as the sum of the elements. Used in an amount of 1300 ppm. The promoter is preferably in the form of a compound, for example in the form of a complex or salt, such as a halide, fluoride, bromide or chloride, or a carboxylate, nitrate, sulfate or sulfide, phosphorus It is applied to the support in the form of acid salts, cyanides, hydroxides, carbonates, oxides, oxalates or as salts of heteropolyacids, for example in the form of rhenium heteropolyacid salts.

The catalyst of the present invention preferably contains molybdenum in an amount of 10-300 ppm, more preferably 10-200 ppm, more preferably 10-80 ppm, calculated as an element, based on the total weight of the catalyst. Molybdenum is preferably as a compound, for example, halide, oxyhalide, oxide, molybdate, permolybdate or as acid, preferably molybdenum oxide, ammonium heptamolybdate, ammonium orthomolybdate, chloride. It is applied as a compound selected from the group consisting of molybdenum, molybdenum fluoride, molybdenum sulfide and molybdic acid. For the purposes of the present invention, molybdenum is particularly preferably applied to the support as molybdic acid (MoO ₃ .H ₂ O).

  The catalyst of the present invention preferably comprises tin in an amount of 10-600 ppm, more preferably 50-400 ppm, more preferably 80-250 ppm, calculated as an element, based on the total weight of the catalyst. Tin is preferably as a compound, for example as a halide, hydroxide, oxalate, oxide, stannate or as an acid, preferably tin oxide, tin chloride, tin fluoride, sodium stannate, hexa It is applied as a compound selected from the group consisting of sodium hydroxostannate, stannic acid and tin oxalate. For the purposes of the present invention, tin is particularly preferably applied to the support as tin oxalate.

  Furthermore, the catalyst of the present invention is tungsten free. For the purposes of the present invention, a tungsten free catalyst is a catalyst having a tungsten content of less than 5 mg / kg, and tungsten is preferably not detectable by analysis. In any case, no tungsten compound is used in the production of the catalyst.

  In a preferred embodiment, the catalyst also comprises silver, molybdenum and tin and at least one further promoter, for example 5, 4, 3 or 2 further promoters or one further promoter. All accelerators known in the prior art are considered as at least one further accelerator. The at least one further promoter is preferably from lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, manganese, rhenium, cadmium, chromium, elemental sulfur and mixtures of two or more thereof. Selected from the group consisting of The catalyst particularly preferably comprises at least one further promoter selected from the group consisting of rhenium, cesium, lithium, chromium, manganese, elemental sulfur and mixtures of two or more thereof. The catalyst very particularly preferably comprises at least rhenium as further promoter and at least one element selected from the group consisting of cesium, lithium, chromium, manganese, sulfur and mixtures of two or more thereof.

  Thus, the present invention also describes a tungsten-free catalyst which is applied to the support and contains silver, molybdenum and tin in an amount of 5 to 35% by weight, based on the total weight of the catalyst, and at least rhenium as a further promoter.

  When the catalyst comprises, for example, rhenium, the catalyst is preferably in an amount of 50-600 ppm, more preferably in an amount of 100-450 ppm, more preferably in an amount of 150-400 ppm, calculated on the total weight of the catalyst and as an element. Of rhenium. Rhenium is preferably applied as a compound, for example as a halide, oxyhalide, oxide, rhenate, perrhenate or as an acid. When rhenium is used as an accelerator, rhenium is preferably ammonium perrhenate, rhenium (III) chloride, rhenium (V) chloride, rhenium fluoride (V), rhenium oxide (VI) and rhenium oxide (VII). Is applied as a compound selected from the group consisting of For the purposes of the present invention, rhenium is particularly preferably applied to the support as ammonium perrhenate.

  When the catalyst contains, for example, cesium, the catalyst preferably contains cesium in an amount of 20 to 850 ppm, in particular an amount of 100 to 600 ppm, calculated as elements, based on the total weight of the catalyst. Cesium is preferably applied to the carrier as a cesium compound. Here, in principle, any suitable cesium compound can be used. Cesium is preferably applied in the form of cesium hydroxide.

  If the catalyst comprises, for example, lithium, the catalyst preferably comprises lithium in an amount of 10 to 450 ppm, in particular 50 to 300 ppm, calculated on the total weight of the catalyst and as an element. Lithium is preferably applied to the support as a lithium compound. Here, in principle, any suitable lithium compound can be used. Lithium is preferably applied in the form of lithium nitrate.

  If the catalyst contains, for example, sulfur, the catalyst preferably contains sulfur in an amount of 5 to 300 ppm, in particular 5 to 150 ppm, calculated on the total weight of the catalyst and as an element. Sulfur is preferably applied to the support as a sulfur compound. Here, in principle any suitable sulfur compound can be used. Sulfur is preferably applied in the form of ammonium sulfate.

  In a particularly preferred embodiment, the catalyst of the present invention comprises rhenium in an amount of 150-450 ppm, cesium in an amount of 100-600 ppm, lithium in an amount of 50-300 ppm, and sulfur in an amount of 5-150 ppm.

  The accelerator, more preferably the accelerator compound, is preferably dissolved in a suitable solvent, preferably water, before application. The support is then impregnated with the resulting solution, preferably containing one or more accelerators. If multiple accelerators are added, they can be applied to the support together in a single impregnation step or separately in multiple impregnation steps. For a solution containing one or more accelerators, it can be prepared by any suitable method. For example, the accelerators can be dissolved separately in one solution each, after which the resulting solution containing in each case one accelerator is used for impregnation. It is likewise possible to dissolve two or more accelerators together in one solution and then use the resulting solution for impregnation. Furthermore, it is possible to combine the resulting solution containing at least one accelerator prior to impregnation and apply the resulting solution containing all accelerators to the support.

  For example, when at least molybdenum, tin, cesium, lithium, sulfur and rhenium are used as promoters, particularly preferred embodiments include at least one solution containing cesium, an additional solution containing molybdenum, and lithium and sulfur. A further solution, a further solution containing tin, and a further solution containing rhenium are prepared. These solutions are applied to the support in separate impregnation steps or are combined to form one solution before application, and are then used for impregnation only. These solutions are preferably applied to the support together with a mixture comprising silver, more preferably as a silver-amine compound, preferably as a silver-ethylenediamine compound.

  With respect to silver application, this can be applied to the support using all the prior art impregnation and vapor deposition methods for producing silver catalysts for preparing ethylene oxide, these methods comprising one or more Impregnation and firing steps can be included. For example, German Offenlegungsschrift 23005112, German Offenlegungsschrift 2521906, European Patent Application Publication No. 0014457, European Patent Application Publication No. 0085237, European Patent Application Publication No. 00384312 German Patent No. 2454927, German Patent No. 3321895, European Patent Application No. 0229465, German Patent No. 3150205, European Patent Application No. 0172565. And the preparation methods for silver catalysts disclosed in EP-A-0357293.

  Silver can be applied separately or together with one or more accelerators. Preference is given to applying a mixture comprising silver and at least one accelerator to the support, for example by impregnation, spraying or mixing steps. The order in which the promoter and silver are applied can generally be arbitrarily selected, i.e., embodiments in which silver and promoter are applied to the support simultaneously are included. Similarly, embodiments are included in which the silver and promoter are applied to the support in various steps, and the order of these steps can generally be selected arbitrarily. Further included are embodiments in which a portion of the accelerator is applied to the support before or after applying the silver and the remaining portion is applied simultaneously with the silver. Preference is given to the simultaneous application of silver and promoter to the support.

  The present invention further provides a method of producing a tungsten-free catalyst for alkene epoxidation comprising the steps of applying silver, molybdenum and tin to a support.

  The application can in principle be carried out by any suitable method, for example by impregnation of the support. Particularly preferably, the application is carried out by vacuum impregnation at room temperature. In vacuum impregnation, the support is preferably initially at a pressure in the range of 500 mbar or less, more preferably at a pressure of 250 mbar or less, particularly preferably at a pressure of 50 mbar or less, and preferably at a temperature in the range 2 ° C. to 50 ° C., more preferably The treatment is performed at a temperature in the range of 5 to 30 ° C., particularly preferably at room temperature. The vacuum treatment is performed, for example, for a period of at least 1 minute, preferably at least 5 minutes, more preferably in the range of 5 minutes to 120 minutes, in particular in the range of 10 minutes to 45 minutes, particularly preferably in the range of 15 minutes to 30 minutes. Do. After vacuum treatment, at least one solution, for example a mixture comprising silver, molybdenum and tin, or at least one solution comprising at least one further promoter, preferably silver, molybdenum and tin and at least one further A mixture containing an accelerator is applied to the carrier. The solution is preferably dripped or sprayed, preferably sprayed. In this case, the application is preferably performed using a nozzle. After application, the carrier is preferably further evacuated. The exhaust is preferably at a pressure in the range of 500 mbar or less, more preferably at a pressure of 250 mbar or less, particularly preferably at a pressure of 50 mbar or less, and preferably at a temperature in the range 2 ° C. to 50 ° C., more preferably 5 ° C. to 30 ° C. It is carried out at a temperature in the range, particularly preferably at room temperature. The vacuum treatment is performed, for example, for a period of at least 1 minute, preferably at least 5 minutes, more preferably in the range of 5 minutes to 120 minutes, in particular in the range of 10 minutes to 45 minutes, particularly preferably in the range of 10 minutes to 20 minutes. Do.

  The step of applying silver, molybdenum, tin and optionally further promoters to the support can be followed by at least one post-treatment step, such as one, two or more drying steps. Drying is usually performed at a temperature in the range of 2 to 200 ° C. The post-processing step is, for example, drying using the above vacuum processing.

  Accordingly, the present invention also provides a method for producing a tungsten-free catalyst for alkene epoxidation comprising the steps of applying silver, molybdenum and tin to a support and a drying step.

  After the step of applying silver, molybdenum, tin and optionally further accelerators, optionally after the drying step, the support material is preferably calcined. The firing is preferably in the range of 150 to 750 ° C, preferably in the range of 200 to 500 ° C, more preferably in the range of 220 to 350 ° C, more preferably in the range of 250 to less than 300 ° C, particularly preferably in the range of 270 to 295 ° C. The calcination time is generally at least 5 minutes or longer, for example, 5 minutes to 24 hours or 10 minutes to 12 hours. The firing time is particularly preferably in the range of 5 minutes to 3 hours. Firing can be performed at a constant temperature. Furthermore, embodiments are included in which the temperature is varied continuously or discontinuously during the firing time.

  Calcination can be performed under any gas atmosphere suitable for this purpose, for example, in an inert gas or a mixture of inert gas and 10 ppm to 21 volume% oxygen. Inert gases that may be mentioned include, for example, nitrogen, argon, carbon dioxide, helium and mixtures of the above inert gases. Nitrogen is particularly preferred when calcination is carried out in an inert gas. In an alternative preferred embodiment, air and / or lean air is used.

  Further, the firing is preferably performed in a muffle furnace, convection oven, rotary furnace and / or belt firing oven.

  Thus, the present invention also provides for the epoxidation of alkenes comprising the steps of applying silver, molybdenum and tin to the support, optionally a drying step, and preferably firing at a temperature in the range of 270-295 ° C. A method for producing a tungsten-free catalyst is also provided.

In a preferred embodiment of the invention, the support material impregnated with silver, molybdenum and tin obtained by the above method having a temperature T ₀ is calcined in a multi-stage process. This process includes at least the following steps:
(1) heating the impregnated support material from temperature T ₀ to temperature T ₁ at a heating rate of at least 30 K / min, preferably in the range of 30-80 K / min, more preferably in the range of 40-75 K / min;
(2) step of holding the temperature _{T 1} of the heated the support material temperature _T 2 _{(T 2} is preferably in the range of 0.95T ₁ ~1.1T _1);
(3) Cooling the carrier material held at temperature T ₂ to temperature T ₃ (T ₃ is 60 ° C. or lower).

The impregnated support material, impregnation, in particular, especially preferred in a single step impregnation, if obtained in T ₀ temperature exceeding, according to the present invention, which initially is cooled to a temperature T _0.

In principle, a temperature T _{0 in} the range up to 35 ° C., for example in the range up to 30 ° C., is conceivable. The temperature T ₀ is preferably in the range of 5 to 20 ° C., more preferably in the range of 10 to 15 ° C.

In a preferred embodiment, the temperature T ₀ , according to the present invention, requires that the resulting impregnated support material be subjected to pre-drying before it is heated in step (1) at a heating rate of at least 30 K / min according to the present invention. There will be no such thing.

  Thus, the present invention preferably provides a support material impregnated with silver, molybdenum, tin and optionally further promoters obtained by the above process, preferably above 35 ° C. before heating at a heating rate of at least 30 K / min. Provides a method that does not subject to temperatures above 30 ° C, more preferably above 25 ° C, more preferably above 20 ° C.

In step (1) of the firing process according to the invention, the impregnated support material provided at temperature T ₀ is heated at a heating rate of at least 30 K / min.

  A heating rate of up to 150 K / min, for example up to 100 K / min or 80 K / min is conceivable. The heating rate in step (1) is preferably in the range of 30 to 80 K / min, more preferably in the range of 40 to 75 K / min.

In step (1) of the firing process according to the invention, the support material is heated from temperature T ₀ to temperature T ₁ .

According to the invention, the heating is carried out to a temperature T ₁ suitable for firing the impregnated support material. Here, in principle, temperatures T ₁ of up to 350 ° C., for example 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 1} is about 250 ° C.. Thus, a temperature T _{1 in} the range of 250-310 ° C. or in the range of 250-300 ° C. is conceivable. However, according to the present invention, it has been found that a firing temperature of less than 300 ° C. can be set. Therefore, the present invention provides the above method wherein the temperature T ₁ is less than 300 ° C., preferably 299 ° C. or less.

According to the present invention, the temperature T ₁ is preferably in the range of 250-295 ° C., more preferably in the range of 260 ° C.-295 ° C., more preferably in the range of 270-295 ° C., more preferably in the range of 270-290 ° C., For example, it exists in the range of 270-285 degreeC, 275-290 degreeC, or 275-285 degreeC.

In principle, there is no limit as to the method for achieving the heating rate according to the invention. Preference is given to contacting the carrier material present at temperature T ₀ with the gas during heating, this gas being used to heat the carrier material, thus allowing this gas to heat the carrier material to temperature T _1. It has further priority to have a temperature.

  As a rule, there is no restriction on the chemical composition of the gas that is brought into contact with the support material in order to heat the support material. Thus, it is conceivable that the gas contains oxygen, and examples include the oxygen content of a gas of up to 100% by volume or up to 25% by volume. For example, the use of air is also conceivable. It is also conceivable that the oxygen content is low, for example a mixture of nitrogen and air, for example lean air. Mention may be made of the oxygen content of a gas of up to 20% by volume or up to 15% by volume or at most 10% by volume or at most 5% by volume or at most 1% by volume. For the purposes of the present invention, it is particularly preferable to use an inert gas or a mixture of two or more inert gases whose oxygen content is preferably in the range of less than 10 ppm, more preferably in the range of 5-9 ppm as the heating gas. have priority. Examples of the inert gas may include nitrogen, carbon dioxide, argon and / or helium. For the purposes of the present invention, nitrogen is particularly preferably used as the inert gas.

Accordingly, the present invention performs the heating in step (1) by contacting the support material with an inert gas I _1, to provide a method.

The present invention provides the above method, wherein the heating of step (1) is preferably performed by contacting the support material with an inert gas I ₁ comprising less than 10 ppm, preferably 5-9 ppm oxygen.

The present invention more preferably comprises the step (1) by contacting the support material with an inert gas I ₁ (the inert gas is nitrogen and the inert gas contains less than 10 ppm, preferably 5-9 ppm oxygen). The above method is performed.

The expression “inert gas I ₁ containing less than 10 ppm, preferably 5-9 ppm oxygen” here refers to a gas mixture comprising inert gas I ₁ and oxygen, oxygen content of less than 10 ppm or 5-9 ppm being a gas With respect to the oxygen content of the mixture, the inert gas I ₁ can be a mixture of two or more inert gases.

  For the purposes of the present invention, the gas that is contacted with the support material during the heating of step (1) is very particularly preferably typically an amount of 99.995 to 99.9999 nitrogen and an amount of 6-8 ppm. Of technical grade nitrogen, preferably obtained from a fraction of air, containing a small amount of oxygen and trace amounts of noble gases.

The temperature of the gas to be in heat contact with the carrier material enables heating rate according to the present invention in principle, be selected so as to be able to support material to a temperature T _1. Gas contacting the support material during the heating step (1) is preferably _T 1 ～1.1T ₁ range, and more preferably _T 1 ～1.07T _1, more preferably in the range of _T 1 ～1.05T Having a temperature in the range of ₁ .

Contacting the support material with the gas in step (1) can in principle be carried out in any desired manner as long as it is ensured that the heating rate according to the invention is achieved for the support material. In this regard, particular preference is given to bringing the support material into contact with a gas stream, preferably an inert gas I ₁ stream, ie passing the gas through the support material. Here, the volumetric flow rate of the gas is basically chosen so that the heating rate according to the invention is achieved. In particular, the gas volume flow rate is selected such that the heating rate according to the invention is achieved by a combination of the gas temperature and volume flow rate in contact with the support material. Volumetric flow rate, particularly preferably in the range of 2500~5000m ³ / time, a range of particularly 3200~4500m ³ / time.

In a preferred embodiment, the present invention passes an inert gas I ₁ , preferably nitrogen, through the support material heated in step (1), and I ₁ preferably contains less than 10 ppm, more preferably 5-9 ppm oxygen. preferably _{I 1} has a temperature in the range of _{T 1 ~1.1T} 1, and _{I 1} is preferably 2500~5000m ³ / hour, more preferably a carrier with a volume flow in the range of 3200~4500m ³ / time There is provided a method as described above for flowing through a material.

While heating the support material according to step (1), the heating rate is at least 30 K / min, preferably from 30 to 30 K / min, calculated from the temperature difference (T ₁ -T ₀ ) ÷ total time required for heating. As long as it is guaranteed to be in the range of 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, it may be constant or variable. The heating rate during the total heating operation is preferably at least 30 K / min, more preferably in the range of 30-80 K / min, more preferably in the range of 30-75 K / min, more preferably in the range of 30-70 K / min. .

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

In step (2) of the firing process according to the invention, the carrier material is heated to a temperature T _1, after heating, preferably immediately after heating, maintaining the temperature T ₂ suitable for the purpose of firing according to the present invention. Here, priority is given to a temperature T ₂ of about temperature T ₁ . Range 0.95~1.1T _1, for _{example, 0.95~1.05T 1, 0.96~1.04T 1, 0.97~1.03T} 1, 0.98~1.02T 1 or 0 temperature _{T 2} in the range of .99～1.01T ₁ is particularly preferential. The temperature _{T 2,} preferably below 300 ° C., preferably selected to be 299 ° C. or less.

Holding the support material at temperature T ₂ also includes embodiments where the value of T ₂ is not constant during the holding time, but instead varies within the above range. Accordingly, the present invention also includes embodiments in which the holding is performed at two or more different temperatures T ₂ within the above range.

Long to keep the carrier material to a temperature T ₂ are not subject to any restriction in principle. For the purposes of the present invention, in step (2), 15 min carriers are preferably prioritized to maintain 2-10 minutes, more preferably for a period ranging from 3 to 5 minutes, the temperature _{T 2} The

In principle, there is no limit as to how the retention according to the invention is achieved in step (2). While kept at a temperature T _2, the carrier material, preferably is contacted with the temperature of the gas make it possible to maintain the carrier to a temperature T _2.

To maintain the carrier material to a temperature T _2, with respect to the chemical composition of the gas to be contacted with the support material, there is no restriction in principle. Thus, for example, it is conceivable that the gas contains oxygen, for example, an oxygen content of gas of up to 100% by volume or up to 25% by volume is possible. For example, use of air is also conceivable. It is also conceivable that the oxygen content is low, for example a mixture of nitrogen and air, for example lean air. Mention may be made of the oxygen content of a gas of up to 20% by volume or up to 15% by volume or at most 10% by volume or at most 5% by volume or at most 1% by volume. For the purposes of the present invention, an inert gas or a mixture of two or more inert gases whose oxygen content is preferably less than 10 ppm, more preferably in the range of 5-9 ppm, as a gas for maintaining the temperature T ₂ . The use of is particularly preferred. Examples of the inert gas include nitrogen, carbon dioxide, argon and helium. Particular preference is given to using nitrogen as an inert gas for the purposes of the present invention.

Accordingly, the present invention performs the holding in step (2) by contacting the support material with an inert gas I _2, provides the above method.

The present invention is preferably a support material, less than 10 ppm, preferably for holding the step (2) by contact with an inert gas I ₂ containing oxygen 5～9Ppm, provides the above method.

The present invention more preferably comprises step (2) by contacting the support material with an inert gas I ₂ (the inert gas is nitrogen, the inert gas containing less than 10 ppm, preferably 5-9 ppm oxygen). A method as described above is provided.

The expression “inert gas I ₂ containing less than 10 ppm, preferably 5 to 9 ppm of oxygen” here refers to a gas mixture comprising inert gas I ₂ and oxygen, and an oxygen content of less than 10 ppm or 5 to 9 ppm is a gas. With respect to the oxygen content of the mixture, the inert gas I ₂ can be a mixture of two or more inert gases.

  For the purposes of the present invention, the gas with which the support material is contacted during the holding of step (2) is very particularly preferably typically nitrogen in an amount of 99.995 to 99.9999% by volume and 6-8 ppm. Of technical grade nitrogen, preferably obtained from a fraction of air, in the amount of oxygen and trace amounts of noble gases.

The temperature of the gas with which the carrier material is brought into contact during the holding of step (2) is basically chosen so that the holding temperature according to the invention is possible. Gas contacting the support material in a holding step (2), preferably in the range of _T 2 ～1.1T _2, more preferably _T 2 ～1.07T _2, more preferably in the range of _T 2 ～1.05T ₂ ranges, for _example, having a temperature of T 2 ～1.04T ₂ range or _T 2 ～1.03T ₂ range or _T 2 range ～1.02T ₂ or range of _{T 2 ~1.01T} 2.

Contacting the carrier material with the gas in step (2) can in principle be carried out in any desired manner, as long as it is ensured that the retention of the carrier material at the temperature T ₂ is achieved according to the invention. . In this regard, particular preference is given to bringing the support material in contact with a gas stream, preferably an inert gas I ₂ stream, ie passing the gas through the support material. Here, the volumetric flow rate of the gas is chosen so that essentially the retention according to the invention of the support material at temperature T ₂ is achieved. In particular, the volume flow of the gas is selected such that the retention according to the invention of the support material at the temperature T ₂ is achieved by a combination of the temperature and volume flow of the gas in contact with the support material. The volume flow rate is particularly preferably in the range of 1000 to 3000 m ³ / hour, more preferably in the range of 1500 to 2000 m ³ / hour.

In a preferred embodiment, the present invention passes an inert gas I ₂ , preferably nitrogen, through a support material maintained at temperature T ₂ in step (2), wherein I ₂ is preferably less than 10 ppm, more preferably 5-9 ppm. of containing oxygen, preferably _{I 2} has a temperature in the range of _{T 2 ~1.05T} 2, and preferably _{I 2} is 1000~3000m ³ / hour, more preferably in the range of 1500~2000m ³ / time There is provided a method as described above for flowing through a carrier material at a volumetric flow rate.

For the purposes of the present invention, an inert gas I ₁ is used as the inert gas I ₂ and, as mentioned above, the volume flow rate of I ₂ can be different from the volume flow rate of I ₁ and / or I _2. The temperature of can be different from the temperature of I ₁ , but is not required.

In step firing process according to the invention (3), the carrier material was kept at the temperature T _2, after the holding, preferably immediately after holding, cooled to a temperature T _3. With respect to the value of T _3, there is no particular restriction as a general rule. For the purposes of the present invention, a temperature T ₃ of 60 ° C. or less is preferred.

In principle, there is no limit as to how the cooling according to the invention is achieved in step (3). During cooling to temperature T ₃ , the support material is contacted with a gas having a temperature that preferably allows the support material to cool to temperature T ₃ .

With respect to the chemical composition of the gas is contacted with a carrier material to cool the carrier material to a temperature T _3, it is not limited in principle. Therefore, for example, it is conceivable to use the inert gas used in step (1) or (2) as the gas. For the purposes of the present invention, the gas for cooling to the temperature T ₃ has an oxygen content of at least 5% by volume, preferably at least 10% by volume, more preferably at least 15% by volume, more preferably at least 20% by volume. Particular preference is given to using a gas having. In particular, according to the present invention, air is used for cooling in step (3).

  In the method of the invention, in step (3), the support material is preferably cooled at a cooling rate in the range of 30-80 K / min, preferably in the range of 40-60 K / min, more preferably in the range of 45-55 K / min. To do.

  The calcined and cooled support material thus obtained can be used as a catalyst immediately after step (3) or it can be stored in a suitable manner.

  Regarding the apparatus used for the firing process, the heating according to the present invention in step (1), preferably the holding according to the present invention in step (2), preferably the cooling according to the present invention in step (3) is as described above. There is essentially no limit as long as it is guaranteed that it can be done. According to the invention, preference is given to an embodiment in which at least the heating of step (1), preferably the heating of step (1) and the holding of step (2) and the cooling of step (3) are also carried out continuously. Particularly preferably, the process according to the invention is carried out in step (1), preferably in a belt calciner, at least for steps (1) and (2).

  Regarding the time for applying the accelerator, the accelerator can be applied after the firing. Similarly, the promoter can be applied to the support together with the silver compound.

  Thus, the invention relates to at least one further accelerator, i.e. for example 5 different further accelerators, 4 different further accelerators, 3 different further accelerators, 2 different further accelerators or Embodiments are included in which one further promoter is applied to the support and the support thus treated is then calcined for the first time as described above to obtain the catalyst according to the invention.

  The present invention further provides a process for preparing ethylene oxide from ethylene comprising the step of oxidizing ethylene in the presence of a tungsten-free catalyst for epoxidation of alkenes comprising silver, molybdenum and tin applied to a support To do.

  Furthermore, the present invention also provides the use of a tungsten free catalyst comprising silver, molybdenum and tin applied to a support for alkene epoxidation.

  According to the invention, epoxidation can be carried out by all methods known to those skilled in the art. Here, all reactors that can be used in the prior art ethylene oxide production process, for example, an externally cooled shell and tube reactor (Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Volume A-10, 117- 135, pp. 123-125, VCH-Verlagsgesellschaft, Weinheim 1987) or reactors with a loose catalyst bed and cooling tubes, eg German Offenlegungsschrift 3,414,717, European Patent No. 0082609 and European Patents It is possible to use the reactor described in the published application 03039748. Epoxidation is preferably carried out in at least one tubular reactor, preferably a shell and tube reactor. The catalyst of the present invention can be used in a composite or structured catalyst bed alone or in admixture with other catalysts.

  The preparation of ethylene oxide from ethylene and oxygen is according to the invention, for example, German Offenlegungsschrift 2521906, European Patent Application No 0014457, German Offenlegungsschrift 2300512, European Patent Application. Publication No. 0172565, German Offenlegungsschrift 2,454,972, European Patent Application Publication No. 0357293, European Patent Application Publication No. 0266615, European Patent Application Publication No. 0085237, European Patent Application It can be carried out under conventional reaction conditions as described in publication 0082609 and European patent application publication 0339748. Inert gases such as nitrogen or gases such as water vapor, and methane inert under the reaction conditions, and optionally reaction modifiers such as halides, hydrocarbons (such as ethyl chloride, vinyl chloride or 1,2-dichloroethane) Can be further mixed into a reaction gas containing ethylene and oxygen molecules. The oxygen content of the reaction gas is preferably in the range in which no explosive gas mixture is present. A suitable composition of the reaction gas for preparing ethylene oxide is, for example, in the range of 10 to 80% by volume, preferably 20 to 60% by volume, more preferably 25 to 50% by volume, particularly preferably based on the total volume of the reaction gas. May contain an amount of ethylene in the range of 30-40% by volume. The oxygen content of the reaction gas is advantageously in the range of 10% by volume or less, preferably 9% by volume or less, more preferably 8% by volume or less, very particularly preferably 7% by volume or less, based on the total volume of the reaction gas.

  The reaction gas preferably contains a reactor conditioner containing chlorine such as ethyl chloride, methyl chloride, vinyl chloride or dichloroethane in an amount of 0-15 ppm, preferably 0.1-8 ppm. The remainder of the reaction gas generally comprises a hydrocarbon such as methane or else an inert gas such as nitrogen. In addition, the reaction gas can also include other materials such as water vapor, carbon dioxide or noble gases.

  The above components of the reaction mixture can optionally contain small amounts of impurities. Ethylene can be used, for example, in any purity suitable for epoxidation according to the present invention. Suitable purities include, but are not limited to, polymer grade ethylene that typically has a purity of at least 99% and chemical grade ethylene that typically has a low purity of less than 95%. Impurities typically include mainly ethane, propane and / or propene.

  Epoxidation is usually carried out at high temperatures. Preference is given to temperatures in the range of 150-350 ° C, more preferably in the range of 180-300 ° C, more preferably in the range of 190-280 ° C, particularly preferably in the range of 200-280 ° C. Thus, the present invention also provides the above process wherein the oxidation occurs at a temperature in the range of 180-300 ° C, preferably in the range of 200-280 ° C.

  The oxidation is preferably carried out at a pressure in the range from 5 bar to 30 bar. The oxidation is more preferably carried out at a pressure in the range from 5 bar to 25 bar, preferably in the range from 10 bar to 20 bar, in particular in the range from 14 bar to 20 bar. Accordingly, the present invention also provides a method as described above, wherein the oxidation is carried out at a pressure in the range of 14 bar to 20 bar.

  The oxidation is preferably performed in a continuous process. When the reaction is carried out continuously, it is preferably in the range of 800-10000 / hour, preferably 2000-6000 /, as a function of the selected reactor type, for example reactor size / cross-sectional area, catalyst shape and size. GHSV (gas space velocity) in the range of time, more preferably in the range of 2500-5000 / hr, is used (numerical values are based on the volume of the catalyst).

  The preparation of ethylene oxide from ethylene and oxygen can advantageously be carried out in a circulation process. Here, the reaction mixture is circulated through the reactor, the newly formed ethylene oxide and the by-products formed in the reaction are removed from the product gas stream after each pass, and the product stream is fed with the required amount of ethylene, oxygen and reaction modifier. After replenishment, it is fed again into the reactor. Separation of ethylene oxide from the product gas stream and subsequent treatment can be performed by conventional methods of the prior art (Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A-10, pages 117-135, 123-125. Page, VCH-Verlagsgesellschaft, Weinheim 1987).

  The invention will be described below by means of examples.

1. General method for preparing the catalyst according to the invention 1.1 Aluminum oxide support used A bimodal alpha aluminum oxide support having a hollow ring geometry and the properties shown in Table 1 was used.

1.2 Production of Silver Complex Solution 550 g of silver nitrate was dissolved in 1.5 l of water at 40 ° C. with stirring. 402.62 g of potassium hydroxide solution (47.8%) was mixed with 1.29 l of water. Thereafter, 216.31 g of oxalic acid was added to the potassium hydroxide solution, dissolved completely, and the solution was heated to 40 ° C. The potassium oxalate solution was then added to the silver nitrate solution (40 ° C.) over a period of about 45 minutes using a metering pump (volume flow rate = about 33 ml / min). After the addition was complete, the resulting solution was stirred at 40 ° C. for an additional hour. The precipitated silver oxalate is filtered off and the resulting filter cake is free of potassium and nitrate (measured by measuring the conductivity of the washings; for the purposes of the present invention, free of potassium and nitrate Washed with 1 liter of water (about 10 liters total), implying a conductivity of less than 40 μS / cm. Water was removed from the filter cake as completely as possible and the residual moisture content of the filter cake was measured. 620 g of silver oxalate having a water content of 20.80% was obtained.

  306 g of ethylenediamine was cooled to about 10 ° C. in an ice bath and 245 g of water was added in small portions. After the water addition was complete, 484.7 g of the resulting (still wet) silver oxalate was added in portions over a period of about 30 minutes. The mixture was stirred at room temperature overnight, after which the residue was removed by centrifugation. The Ag content of the remaining clear solution was measured refractometrically and the density was measured using a 10 ml graduated cylinder.

  The solution contained 29.35% by weight of silver calculated as an element and had a density of 1.536 g / ml.

1.3 Preparation of Cobalt or Palladium Complex Solution 12 g of water was cooled to 8 ° C. using an ice / water mixture, and 10 g of ethylenediamine was slowly added little by little. Then, 12.7 g of palladium acetate (Pd 45.9-48.4%) or 10.0 g of cobalt acetate (about 33% Co) was added slowly so that the temperature did not exceed 20 ° C.

1.4 Preparation of Tin Oxalate Solution The desired amount of tin oxalate was weighed and mixed with 4 parts distilled water and 1 part H ₂ O ₂ (30% strength). The reaction mixture was stirred at room temperature until a clear solution was formed.

1.5 General Method for Producing Solution Containing Silver and Accelerator The silver complex solution produced by Method 1.2 was placed in a reaction vessel. An aqueous solution containing lithium and sulfur (lithium nitrate and (NH ₄ ) ₂ SO ₄ ), an aqueous solution containing cesium (CsOH), an aqueous solution containing cesium (CsOH) and tungsten (H ₂ WO ₄ ), an aqueous palladium-ethylenediamine complex solution, cobalt -An ethylenediamine complex aqueous solution, an aqueous solution containing tin (tin oxalate, SnC ₂ O ₄ ), an aqueous solution containing molybdenum (molybdic acid, H ₂ MoO ₄ ), and / or an aqueous solution containing rhenium (ammonium perrhenate) To this and the solution was stirred for 5 minutes. Solutions for use with specific catalysts and their amounts are detailed in the examples in item 2.

1.6 Application of solution to carrier The desired amount of carrier A (see Table 1) was placed in a rotary evaporator and evacuated. The vacuum was 50 mbar. The support was pre-evacuated for about 10 minutes.

  The solution obtained by method 1.5 was added dropwise to the support over a period of 15 minutes and under reduced pressure, after which the impregnated support was spun for an additional 15 minutes under reduced pressure. The carrier was then placed in the apparatus for 1 hour at room temperature and atmospheric pressure and gently mixed every 15 minutes.

1.7 Firing the impregnated support The impregnated support was heated at 283 ° C. under 8.3 m ³ N ₂ per hour with a heating rate of 40 K / min, a heating time of 360 seconds and a holding time of 283 ° C. of 420 seconds. Treated in a convection oven (HORO, model 129ALV-SP, serial number: 53270) for 13 minutes. Cooling to room temperature was performed over a period of 420 seconds.

1.8 Production of pulverized catalyst material The obtained catalyst ring was roughly pulverized in a porcelain dish using a mortar. The ground material was then ground to the desired particle size fraction (500-900 μm) using a sieving machine (Fritsch) and two balls made of sintered alumina. The extremely hard ring was completely ground using a mortar and then screened.

1.9 Epoxidation Epoxidation was performed in an experimental reactor comprising a vertical reaction tube made of stainless steel with an inner diameter of 6 mm and a length of 2200 mm. The reaction tube equipped with the jacket was heated using hot oil of temperature T flowing through the jacket. In a very good approximation, the temperature of the oil corresponds to the temperature in the reaction tube and hence the reaction temperature.

  For epoxidation, the catalyst was used in the form of ground catalyst material (particle size fraction 500-900 μm). The reaction tube is filled with inert steatite balls (1.0 to 1.6 mm) up to a height of 212 mm from the bottom upward, and the ground catalyst material (particle size 0.5 to 0 to 1100 mm from above). .9 mm) was filled with 38.2 g and filled with inert steatite balls (1.0-1.6 mm) to a height of 707 mm from above. The feed gas entered the reactor from the top, passed through the catalyst bed and exited from the bottom again.

The feed gas contained 35% by volume of ethylene, 7% by volume of oxygen, 1% by volume of CO ₂ and an appropriate amount of EC. Initially, 2.0 ppm EC (ethylene chloride) was used for initiation. Depending on the catalyst and performance, the EC concentration was increased to a maximum of 8 ppm every 24 hours. The remainder of the feed gas contained methane. The experiment was carried out at a pressure of 15 bar and a gas space velocity (GHSV) of 4750 1 / hour and a space-time yield of EO of 250 kg / (m ³ cat × hour).

  The reaction temperature was controlled to obtain a predetermined ethylene oxide offgas concentration of 2.7%. In order to optimize the catalyst with respect to selectivity and conversion, 2.2-4.0 ppm of ethylene chloride was added as a regulator to the feed gas.

  The gas exiting the reactor was analyzed using online MS. Selectivity was determined from the analysis results.

  The results are summarized in Table 2. This table shows the performance values of the stable operating state with the optimal EC dosage after a run-in period of more than 100 hours of catalyst operating time.

2. Catalyst produced:
2.1 Catalyst 1 (Comparative Example)
300 g of support A was converted into the corresponding catalyst according to the general method 1.2-1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
Silver complex solution 190.25g (Ag 28.83%)
2.3698 g of a solution containing 2.85% lithium and 0.21% sulfur
3.5593 g of a solution containing 2.00% tungsten and 4.00% cesium
3.2991 g of a solution containing 4.1% rhenium

  The produced catalyst comprises 15.4 wt% silver, 200 wtppm tungsten, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, And 380 ppm of rhenium. The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.2 Catalyst 2 (Comparative Example)
119.9 g of support A was converted to the corresponding catalyst according to the general method 1.2-1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
75.64 g of silver complex solution (Ag 29.14%)
0.95 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4241 g of a solution containing 4.00% cesium
1.3210 g of a solution containing 4.1% rhenium
0.0681 g of water

  The catalyst produced contains 15.5 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, and 380 ppm rhenium.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.3 Catalyst 3 (according to the invention)
120.2 g of support A was converted to the corresponding catalyst according to the general method 1.2 to 1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
73.63 g of silver complex solution (Ag 29.14%)
0.9458 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4182g of solution containing 4.00% cesium
0.3576 g of a solution containing 2.00% of molybdenum
1.0632g of solution containing 2.00% tin
1.3136 g of a solution containing 4.1% rhenium

  The catalyst produced was 15.2 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 50 ppm molybdenum, 150 ppm. An amount of tin and an amount of rhenium of 380 ppm.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.4 Catalyst 4 (Comparative Example)
119.9 g of support A was converted to the corresponding catalyst according to the general method 1.2-1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
71.83 g of silver complex solution (Ag 29.24%)
0.9439 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4125 g of a solution containing 4.00% cesium
0.3551 g of a solution containing 2.00% of molybdenum
1.3101 g of a solution containing 4.1% rhenium
2.5033 g of water

  The catalyst produced was 14.9 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 50 ppm molybdenum, 380 ppm. With a quantity of rhenium.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.5 Catalyst 5 (Comparative Example)
120.0 g of support A was converted to the corresponding catalyst according to the general method 1.2 to 1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
71.90 g of silver complex solution (Ag 29.24%)
0.9439 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4149g of solution containing 4.00% cesium
1.0622g of solution containing 2.00% tin
1.3121 g of a solution containing 4.1% rhenium
1.7943 g of water

  The catalyst produced was 14.9 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 150 ppm tin, 380 ppm. With a quantity of rhenium.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.6 Catalyst 6 (Comparative Example)
120.1 g of support A was converted to the corresponding catalyst according to the general method 1.2-1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
Silver complex solution 74.16g (Ag29.55%)
0.9490 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4256 g of a solution containing 4.00% cesium and 2.00% tungsten
0.3558 g of a solution containing 2.00% of molybdenum
1.0683g of solution containing 2.00% tin
1.3191 g of a solution containing 4.1% rhenium

  The catalyst produced was 15.3 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 200 ppm tungsten, 50 ppm An amount of molybdenum, an amount of 150 ppm of tin, and an amount of rhenium of 380 ppm.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.7 Catalyst 7 (Comparative Example)
120.1 g of support A was converted to the corresponding catalyst according to the general method 1.2-1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
Silver complex solution 75.17g (Ag29.35%)
0.9506 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4247 g of a solution containing 4.00% cesium
0.2410 g of a solution containing 9.00% cobalt
0.0701 g of a solution containing 10.6% of palladium
1.3220 g of a solution containing 4.1% rhenium
0.4253 g of water

  The catalyst produced was 15.5 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 50 ppm palladium, 150 ppm. An amount of cobalt and an amount of rhenium of 380 ppm.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.8 Catalyst 8 (Comparative Example)
120.1 g of support A was converted to the corresponding catalyst according to the general method 1.2-1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
Silver complex solution 75.19g (Ag29.35%)
0.9502 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4270 g of a solution containing 4.00% cesium and 2.00% tungsten
0.2428 g of a solution containing 9.00% cobalt
0.0693 g of a solution containing 10.6% palladium
1.3199 g of a solution containing 4.1% rhenium
0.4134 g of water

  The catalyst produced was 15.5 wt% silver, 400 wtppm cesium, 200 ppm wt tungsten, 190 wtppm lithium, 14 wtppm sulfur, 50 ppm wt. An amount of palladium, an amount of cobalt of 150 ppm, and an amount of rhenium of 380 ppm.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.9 Catalyst 9 (Comparative Example)
120.2 g of support A was converted to the corresponding catalyst according to the general method 1.2 to 1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
75.23g of silver complex solution (Ag29.35%)
0.9505 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4260 g of a solution containing 4.00% cesium
0.2408 g of a solution containing 9.00% cobalt
0.3582 g of a solution containing 2.00% of molybdenum
1.3222 g of a solution containing 4.1% rhenium
0.1344 g of water

  The catalyst produced was 15.5 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 150 ppm cobalt, 50 ppm. An amount of molybdenum and an amount of rhenium of 380 ppm.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

2.10 Catalyst 10 (Comparative Example)
120.2 g of support A was converted to the corresponding catalyst according to the general method 1.2 to 1.7.

The following amounts were used in the preparation of the solution according to general method 1.5:
Silver complex solution 74.38g (Ag29.35%)
0.9496 g of a solution containing 2.85% lithium and 0.21% sulfur
1.4263 g of a solution containing 4.00% cesium
0.2388 g of a solution containing 9.00% cobalt
1.0707g of solution containing 2.00% tin
1.3101 g of a solution containing 4.1% rhenium

  The catalyst produced was 15.5 wt% silver, 400 wtppm cesium, 190 wtppm lithium, 14 wtppm sulfur, 150 ppm cobalt, 150 ppm An amount of tin and an amount of rhenium of 380 ppm.

  The resulting catalyst was then tested according to General Method 1.9. The results are shown in Table 2.

  The catalytic results show that the catalyst 3 according to the invention exhibits the best combination of activity and high selectivity. Under selected experimental parameters, a catalyst that requires a temperature in excess of 245 ° C. to achieve the desired ethylene oxide offgas concentration of 2.7% is suitable to achieve the normally required operating life of about 1 year. Not.

Claims (13)

  A tungsten-free catalyst for the epoxidation of alkenes comprising silver, molybdenum and tin applied to the support.   The catalyst according to claim 1, wherein the support is an aluminum oxide support.   The catalyst of claim 2, wherein the aluminum oxide has a purity of at least 85%.   The carrier has a bimodal pore distribution, preferably a bimodal pore distribution comprising pores having a pore diameter in the range of at least 0.1 to 10 μm and pores having a pore diameter in the range of 15 to 100 μm The catalyst according to any one of claims 1 to 3.   The catalyst according to any of claims 1 to 4, comprising silver in an amount of 5 to 35% by weight.   6. A catalyst according to any one of the preceding claims comprising molybdenum in an amount of 10-300 ppm and tin in an amount of 10-600 ppm, calculated as elements, based on the total weight of the catalyst.   7. The accelerator according to claim 1, further comprising at least one further accelerator, preferably an accelerator selected from the group consisting of rhenium, lithium, sulfur, cesium, chromium, manganese and mixtures of two or more thereof. The catalyst according to 1.   8. A catalyst according to any preceding claim, comprising rhenium in an amount of 50-600 ppm, calculated as an element, based on the total weight of the catalyst.   A method for producing a tungsten-free catalyst for alkene epoxidation comprising applying silver, molybdenum and tin to a support.   The method according to claim 9, comprising a drying step.   11. A method according to claim 9 or 10, comprising calcining at a temperature in the range of 270-295 [deg.] C.   A process for preparing ethylene oxide from ethylene comprising the step of oxidizing ethylene in the presence of a catalyst according to any of claims 1-8.   Use of a catalyst according to any of claims 1 to 8 for the epoxidation of alkenes.