Silver catalyser

<td>POLAND REPUBLIC ICE</td><td>PATENT DESCRIPTION</td><td colspan="2"> 89083</td>

<td></td><td>Additional Patent</td><td colspan="2">MKP BOlj 11/20</td>

<td></td><td>LUJ pULeilLU III</td><td></td><td></td>

<td></td><td>Reported: 05.01.73 (P. 160171)</td><td></td><td></td>

<td>OFFICE</td><td>Priority: 07.01.72 United States of America</td><td colspan="2">Int. Cl? B01J 23/50</td>

<td>patent</td><td>The application was announced: 01.08.74</td><td>j C1YTCLNIA</td><td></td>

<td>PRL</td><td>Patent description published: 30.12.1977</td><td>l ''? du · 'F- τη</td><td></td>

The inventor:

Patent holder: Shell Internationale Research Maatschappij Β. V. The Hague (Netherlands)

Oxidation catalyst and method for the preparation of oxidation catalyst and

The present invention relates to a new oxidation catalyst containing silver on a porous refractory support and containing one or more alkali compounds.

In particular, the invention relates to modified silver catalysts that can be used in oxidation processes, and in particular in the production of ethylene oxide by direct oxidation of ethylene with molecular oxygen. The invention also relates to methods for producing modified silver catalysts.

Supported silver-containing substances are known as useful catalysts for the production of ethylene oxide by controlled, incomplete oxidation of ethylene with molecular oxygen. Many different modifications have been proposed to increase the activity and selectivity silver catalysts. These modifications concerned, for example, the choice of support, the production method, the physical form of silver on the support, and some catalyst additions.

From US Patent No. 2125333 it is known that small amounts of alkali metal, including sodium or potassium and / or their eoM may be added to various silver catalysts used in the production of ethylene oxide. However, later the results of the experiments were contradictory regarding the influence of alkaline compounds.

In US Patent No. 2233474, it is written that while the addition of sodium hydroxide more or less increases the activity of oxide catalysts, potassium hydroxide negatively affects the behavior of the catalyst. After⁵ moreover, US Patent No. 2,765,283 describes that the addition of 1 to 2000 ppm by weight of an inorganic chlorine compound, e.g. sodium chloride, to the support, prior to the introduction of silver, improves the finished catalyst. In American¹⁰ Patent No. 2799687, however, describes that when introducing from 20 ppm to 1.6% by weight of inorganic, sodium or potassium chloride as separate solid particles added to the fluidized bed of the sre catalyst¹⁵ , the halide acts as an inhibitor and therefore reduces the activity of the catalyst.

Accordingly, there is no doubt that the addition of alkali metal compounds to the silver catalyst used for the manufacture²⁰ ethylene oxide either way or rather changes the properties of this catalyst. However, there is no information about the real benefits of using a specific amount of alkali metal, or about the chemical advantages,²⁵ one alkali metal relative to other alkali metals.

At present, it has surprisingly been found that it will add 0.06035 to 0.0030 grams of weight per kilogram to the carrier (in terms of

O / J weight of the entire catalyst) of one or more ions 89,083

083 more alkali, such as potassium, rubidium or cesium, including silver, increases the selectivity of the catalyst thus obtained.

In contrast, it has been found that the addition of lithium or sodium ions causes this increased selectivity to disappear. It has also been found that the addition of larger or smaller amounts of potassium, rubidium and / or cesium is not beneficial and that the introduction of the desired amount of lye (based on weight equivalent) by weight) to the carrier, it gives little or no benefit before adding silver.

The present invention relates to an improved (silver catalyst suitable for the production of ethylene oxide. In addition to silver on a refractory support, this catalyst contains from 0.00035 to 0.0030 solids per kilogram (based on the weight of the entire catalyst) of one or more metal ions alkali, such as potassium and / or rubidium and / or cesium, as cations which are deposited on the support simultaneously with silver.

According to the invention, the catalyst consists of a porous, refractory support containing on the outer and inner (pores) surface from 1.5 to 20% by weight (based on the weight of the entire catalyst), silver and some potassium, rubidium and / or or cesium. Unless otherwise stated, these three metals are understood as alkali metals in the remainder of the description. Excellent results were achieved with each of these three metals. The greatest economic benefits are provided by the use of potassium, while the use of cesium leads to the largest increase in selectivity. The introduction of rubidium gives a better catalyst than in the case of potassium. The use of alkali metal mixtures is also suitable.

Alkali metals are found in the catalyst rather in the form of sulfates. of its ions than as very active, free metals' (akalic. On the other hand, silver in the finished catalyst is in metallic form.

The amount of metal (or metals) on the surface of the catalyst is essential. It turns out that for each of these three metals, a content below 0.0003 weight factor (grw) has a kilogram or above 0.0032 grw per kilogram, it does not give a real improvement in the properties of the catalyst. The content of each and these metals. on the catalyst, one or in combination with other alkali metals of this group, it should be from about 0.00035 to about 0.0030 grw has a kilogram of ready catalyst, and preferably from about 0.0004 to 0.0027 grw per kilogram of ready catalyst. According to the method of this invention, within these contents there are smaller variations in the concentration of each of those alkali metals at which optimum selectivity is achieved by using this catalyst for partial oxidation of ethylene to ethylene oxide. Therefore, the optimal content of a given alkali metal should be given individually for each of these metals. The optimal concentration for potassium is from 0.00077 to about 0.0023 grw per kilogram of finished catalyst, and preferably from about 0.0010 to about 0.0021 grw has a kilogram of ready catalyst. The optimal concentration for rubidium is from about 0.0006. up to about 0.0030 grw per kilogram of finished catalyst, &lt;preferably 0.00075 to about 0.0027 grw per kilogram of finished catalyst. The optimal concentration for cesium is from about 0.00035 to about 0.019 grw per kilo of catalyst, and preferably from about 0.00040 to about 0.0017 grw per kilogram of finished catalyst. The content of metals and dk &lt;alkali may also be expressed in parts per million by weight (ppm by weight) on a weight basis. · The whole catalyst. In ppm units, potassium can therefore be used in an amount of 30 to 90 ppm by weight based on the weight of the entire catalyst, preferably 35 to 85 ppm by weight, preferably 40 to 80 ppm ²⁰ by weight. Analogous values ​​for rubidium are from 66 to 248 ppm by weight, preferably from 77 to 240 ppm by weight, and most preferably from 88 to 232 ppm by weight and for cesium and cod. 26 to 252 ppm by weight, more preferably and &lt;from 28 to 238 ppm by weight, and most²⁵ better from 30 to 226 ppm by weight.

It should be clarified that the amount of potassium, rubidium and / or cesium described above does not have to determine the total amount of metals in the catalyst. the amounts of alkali metals indicated above determine the amounts occurring on the surface of the catalyst, added to (the catalyst simultaneously with silver. Depending on the method of preparation of the support, it often contains in its pores significantly amounts, up to 10,000 ppm by weight, of alkali metals, usually potassium . The amount of alkali metal present in the support, in contrast to the amount introduced onto the surface simultaneously with (silver, does not affect (according to the method of this invention, it improves the properties of the catalyst and is negligible in the calculation of the metal content (akalic).

According to the invention, the catalysts contain from 3 to 15% by weight of metallic silver based on the weight of the total catalyst, preferably from 4 to 13% by weight of silver. The use of larger amounts of silver is possible but not very economically advantageous. Silver deposits on the internal and external surfaces of the catalyst and it should be evenly distributed on these surfaces.

The physical form of silver deposited on the support may change and it has not been found to have a significant effect on the catalyst properties. Excellent results have been obtained using a catalyst containing a certain amount of metal (akic on the surface when Isrebro is present in the form of homogeneous, discontinuous, adjacent, substantially hemispherical particles of uniform diameter below 1 micron, i.e. 10,000 a . The best results with this type of catalyst are obtained when the diameter of the silver particles is between 1000 and 10,000 · A and the average diameter is between 1,500 and 7,500 A.

According to the invention, a variety of typical porous, refractory supports can be used as carrier according to the invention, or inert carrier materials which are inert to the raw material and the products of uittemama ethylene ⁱⁿ pulled in the reaction. They can be natural or synthetic substances, preferably with a micro-pore structure, i.e. having a specific surface below 10 m²/^[g, and preferably below 2 m²/ G. Such carrier substances typically have an apparent porosity of over 20%. Silica and / or clay mixtures are very good carriers here. Particular examples of suitable carriers are alumina, e.g. substances sold under the trade name 'Aluindum', charcoal, pumice, magnesium oxide, zirconia, silicagel (wood), Marska clay, silicon carbide, porous mixtures containing silicon and / or silicon carbide, magnesium oxide, selected clays, natural and ^ fattening zeolites, gelled metal oxides containing heavy metal oxides, taity and molybdenum or tungsten, ceramics, etc.

According to the invention, particularly useful, refractory carriers for preparing the said catalyst are alumina materials, especially those containing alpha alumina. Among the carriers containing alpha alumina, the best are those whose specific surface area measured by the BET method is from 0.03 to 1.0 m²/ g and apparent porosity determined by a typical mercury or water adsorption method is from 25 to 50% by volume. The BET method for determining the specific surface area is described in detail by S. Brunauer, PH Emmet and E. Teller, J. Am. Chem. Soc., 60, 309-16 (1938).

The benefits of adding a special alkali metal are particularly evident in the case of the life of supports containing certain types of naphtha-alumina. These carriers exhibit relatively uniform pore diameters and have a specific surface area (BET) of 0.1 to 0.8 m²/ g, and better 0.15 to 0.6 m²/ g and apparent porosity from 42 to 56%, and preferably from 46 to 52%. Specific examples of these recommended lalfa-alumina supports are the "Alundiun" type LA-956, LA-5556 and LA-4118, sold by Norton Company. Detailed information on these carriers is given in Table I.

Table I

<td>Carrier</td><td>LA-956</td><td colspan="2">LA-5556 | LA-4118</td>

<td>Specific surface area, m²/ g</td><td> 0,17</td><td> 0,24</td><td> 0,35</td>

<td>Apparent pore volume, cm³ Ig</td><td> 0,19</td><td> 0,25</td><td> 0,31</td>

<td>Average diameter • pores, microns</td><td> 2,5</td><td> 4,4</td><td> 5,7</td>

<td>Percentage of pores with diameters between 1.5 to 15 microns</td><td> 79</td><td> 81</td><td> 47</td>

Regardless of the properties of the carrier used, it is prepared in the form of particles, blocks, pieces, lozenges, rings, balls, etc. suitable for use in a fixed bed. A typical (industrial solid bed in ethylene oxidation reactors consists of many parallel, elongated pipes (in a suitable shell) with a diameter of about 2.5 to 5.1 cm and a length of 7 to 14 m, filled with a catalyst. The carrier for such reactors should be formed in the form of rounded particles, such as balls, pellets, rings or tablets, with diameters from 2.5 to 20.3 mm.

To sum up, a suitable catalyst obtained according to the invention contains from 1.5 to 20% by weight (based on the weight of the entire catalyst) of silver and from 0.00035 to 0.0030 grw per kilogram of potassium, rubidium and / or cesium catalyst, homogeneously dispersed together with silver on the surfaces of a porous and refractory carrier.

The recommended catalyst contains from 3 to 15% by weight of silver and 0.00040-0.0027 grw per kilogram of pofas / rubidium and / or cesium catalyst uniformly deposited simultaneously on the internal and external surfaces of the porous alumina carrier with a specific surface area of ​​0.03 up to m2 / g. The best catalyst contains from 4 to 13% by weight of silver · in the form of adjacent, semi-circular, discontinuous particles with a homogeneous diameter less than 1 micron, simultaneously deposited together with 0.00040-0.0019 grw per kilogram of potassium, rubidium and / or cesium and evenly (distributed on the inner and outer surfaces of the naphtha-alumina carrier with a specific surface area of ​​0.1 to 0.8 m2 / g.

According to the method of the invention, the kaitatalizer must of course (be prepared in such a way that silver and the desired alkali metal (metals) are simultaneously deposited on the surface of the support, since it was found that simultaneous silver deposition has a significant impact on the effectiveness of alkali metal additives.

There are many known methods for introducing silver into a medium. The carrier may, for example, be impregnated with an aqueous solution of silver nitrate, dried and reduced to silver with hydrogen or hydrazine, such as in US Patent No.

575 888. The support can also be impregnated with a gamoniacal solution of oxalate or carbonate and metallic silver obtained by thermal decomposition of oxalate. The carrier can also be impregnated with special aqueous solutions of silver salts in combination with ammonia, neighboring (in the homologous series) and α-aminoamines and alkyl diamino amines, followed by thermal decomposition according to the PRL patent specification No. 73512.

It is also possible to introduce silver by impregnating the support with a silver salt solution containing ethanoroamro and reducing according to Japanese Patent Specification No. 19606/1971 or by adding a slurry of fine silver carbonate particles to the support and thermal decomposition according to US Patent No. 3043854. According to each of these methods silver is added to the support by contacting the support with the liquid phase, i.e. iiaLbo, with a silver solution or with a slurry of silver particles. These methods are great for introducing the desired alkali metals. They allow for the simultaneous · deposition with silver by dissolving the appropriate salts · of these metals in the liquid phase in such an amount that after introducing the support into it in the finished catalyst obtain the desired alkali metal content. , Suitable are those salts of the alphcal metal that dissolve in the liquid phase used for silver deposition.

No one was found. ^ &lt;3 ^^^ (^ the effect of the anion of the alkali metal salt on the operation of the catalyst. Nitrates may be used, for example,

- * nitrites, chlorides, iodides; 'bromides, acid' carbonates, oxalates, acetates, tartrates, lactates, isopropoxides and other similar alkali metal salts. However, the use of alkali metal salts which react with silver from the liquid phase should be avoided, which could compete for the premature precipitation of silver salts from the loading solution. For example, potassium chloride cannot be used according to this method if an aqueous solution of silver nitrate was used, but it can be used if an aqueous solution of amino silver complexes from which silver chloride does not precipitate was used for silver deposition.

Generally speaking, according to the method of the invention, the catalyst is prepared by plugging in a suitable solid, porous, refractory liquid phase support containing a certain amount of silver as a silver compound dissolved in the liquid phase or as a slurry of particles of a silver compound, in an amount sufficient to deposit from up to 20% by weight of silver on the surface of the support, the 'Cekła' phase also contains a certain amount of dissolved potassium salts, sufficient rubidium and / or cesium for deposition on the support surface from 0.00035-0.0030 grw per kilogram of these alkali metals in the form of (salts, thus the simultaneous deposition of this amount of silver compounds and salts of caicidal metals on the surface of the catalyst, followed by the resulting product containing the silver compound and the alkali metal salt is subjected to thermal treatment in the presence of a reducing agent to convert silver sicaLi to metallic silver.

Suitable solutions for impregnation contain, for example, from 3 to 40% by weight of silver salt and from 25 to 500 ppm by weight of the desired metal (s); Determination of the exact concentration values ​​generally requires experimental tests, since the amount of alkali metal deposited from the solution, which is crucial, depends in part on the porosity of the support used. However, methods for depositing different silver and / or alkali metal concentrations as well as methods for analytically determining the amount of actually deposited material are well known.

The method of the invention 'comprises an alternative and specific method of simultaneously depositing silver salt and an alkali metal on a surface of a support. There is an easy method of depositing a certain amount of alkali metal, i.e. a quantity determined by the method of this invention, from 0.00035 · 0.0030 grw per kilogram of ready catalyst. According to this method, a larger amount of alkali metal should be deposited simultaneously with the silver method described above. Then, the particles of the catalyst thus obtained are contacted with anhydrous alcohol with 1 to 2 carbon atoms.

The alkali metals discussed in this invention dissolve in such alcoholic solvents to a sufficient degree that after one or several alcohol washes, the excess is simultaneously removed with silver of the deposited alkali metal. The amount of alkali metal remaining on the support is in the range of concentrations typically found in this way. This method is a simple method of choosing the concentration of metal / alkiaiazene from its content, which affect the catalyst adversely to the concentration within the limits of the method of this invention, which method can easily be used on a lower industrial scale.

The selected variant of this general method is described in more detail below. After heat treatment, the purpose of which is to decompose the silver compound into metallic silver, the catalyst contacts the lower alcohol with 1 or 2 carbon atoms, i.e. methanol or ethanol. · You can also use a mixture of these two alcohols.

Slight CLoścs may be present in the solvent, e.g. up to about 5% by volume of other substances, such as for example benzene impurities in ethanol. The use of absolute and anhydrous alcohol is preferred. Avoid larger amounts of water. The temperature of the dissolution process in alcohol is not critical. The best results are obtained when using alcohol heated to a temperature from about 40 ° C to the boiling point of lacohol (methanol 65 ° C and ethanol 78 ° C).

Alcohol can be used in various amounts. When running the process in the tank, use enough alcohol to completely immerse the catalyst. In this case, the best results are obtained when the catalyst is immersed in fresh alcohol 2 to 4, preferably 3 times. Each such rinse is usually carried out within 5 to 30 minutes, although the said period of time is not critical. It should be noted that such a tank process can easily be adapted to the continuous method. After rinsing with LiUkohiol, the catalyst should be separated from the solvent. This generally requires screening and drying the catalyst by heating and passing larger amounts of drying gas over it, such as air, nitrogen, methane, ethylene, etc. Drying must be carried out to the end because the alcohol content of the catalyst is a potential impurity of ethylene oxide.

The addition of an alkali metal according to the invention is particularly effective when introducing silver into the support from an alkaline solution, in particular a basic solution containing a nitrogenous base. Examples of such nitrogenous bases are: ammonia, alkylamines and alkanolamines.

Thus, according to the invention, the catalyst is prepared by introducing into the porous alumina support from 3 to 15% by weight of silver in the form of a water-soluble * silver salt &lt;from 0.00035. up to 0.0030 grw per kilogram of potassium, rubidium and / or cesium in the form of water-soluble soda 'by contacting the carrier with an alkaline, aqueous solution of silver salt and lalikaii metal. and maintaining the product. obtained at a temperature of 100 to 500 ° C in the presence of a reducing agent over a period of time sufficient to convert silver salts into metallic silver.

A preferred modification of this method is to saturate the alumina support with certain aqueous solutions containing alkali metal and silver salts, followed by thermal reduction of the silver salt. The solution used for impregnation contains: a silver carboxylic acid salt, an alkaline solution of a lamina 'dissolving reducing agent, a potassium, rubidium and / or cesium salt, and an aqueous dissolver. Examples of suitable silver carboxylic acid salts and organic amine solutions that dissolve reducing agents as well as aqueous solvents are given in Polish Patent No. 73512.

It is also possible to use alkali metal salts of inorganic and noganic carboxylic acids. It is often convenient to use an alkali metal salt of the same carboxylic acid in the silver salt of a carboxylic acid, e.g. potassium oxalate, rubidium or cesium if silver oxalate is used.

The essential thing is that there is only a certain (specified amount of three udkalic metals). These amounts can be obtained by adding a certain amount of alkali metal salt to a silver solution containing no alkali metal salt or insufficient alkali metal salt, or by removing a specific amount of alkali metal salt from a solution that contains too much of it, or by removing and surface of the carrier determined the amount of alkali metal after deposition greater than the amount of metal needed.

For example, silver oxalate solution can be obtained by two methods. Silver oxide • may be reacted with a mixture of ethylene diamine and oxalic acid to form a solution containing a complex of silver oxalate and ethyl diquuaimine, to which a specific amount of potassium and optionally other amines such as ethanolamine are added. Alternatively, silver sorrel can be precipitated from a solution of potassium oxalate and silver nitrate, and washed several times to remove the salt. potassium &lt;until the desired potassium content is reached. Silver oxalate containing potassium is then dissolved in ammonia and / or amines.

When the support contacts the solution as described above, silver and alkali metal (s) simultaneously deposit on the surface of the support in the form of suitable salts.

The saturated support is in turn heated at a temperature of 100 to 375 ° C, preferably 125 to 325 ° C, for a period of time, usually 0.5 to 8 hours, needed to decompose the silver salt and form a layer of metallic silver particles on the surface. Avoid using than. szych -terniperatuir due to incomplete decomposition of silver salts. You do not need to use the same temperature to break down the silver salts.

Alternatively, a solution of the ethylene diamine complex and silver oxalate containing a greater than needed amount of alkali metal may be used. · '

When adding the nakalic metal and according to the invention in combination with the best silver deposition method, the resulting silver catalyst contains silver in the desired form of fine homogeneous particles.

It has been found that the silver catalysts produced according to the invention promoted by alkali metal have a particularly high selectivity in the direct oxidation of ethylene with molecular oxygen to ethylene oxide. Oxidation reaction conditions in the presence²⁰ such catalysts include the process parameters described above. This applies, for example, to temperatures, pressures, residence times, diluents such as nitrogen, carbon dioxide, steam, argon, methane or other grades2⁵ hydrocarbons, catalyst moderators, e.g. 1,2-dichloroethane, vinyl chloride or chlorinated polyphenyl compounds, process methods,. e.g. with recycling or subsequent conversion in various reactors to increase ethylene oxide yield and other specific oxide production process conditions. ethylene.

Generally, atmospheric pressure up to about 35 atm is used, although it is not necessary. higher pressure applications. The molecular oxygen used as the reactant can be obtained typically. ways. A relatively pure Uenu stream, a concentrated oxygen stream containing mainly oxygen and a small amount of one or more diluents, such as nitrogen, argon, or other oxygen-containing stream, e.g. air, may be used. It is clear, therefore, that the use of these new silver catalysts in ethylene oxidation reactions in no way limits the specific conditions for carrying out this process by known methods.

Selected method of producing ethylene oxide using the catalyst of the invention. involves contacting the quenching of an oxygen-containing gas, evolved from air and containing not less than 95% oxygen, with ethylene in the presence of a catalyst at a temperature of 210 to

285 ° C, preferably 225 to 270 ° C.

The use of silver catalysts discussed here in ethylene oxide production processes by contacting an oxygen-containing gas with an ethylene-containing gas under the conditions of ethylene oxide ιprcwαdz / to obtain fully selective oxidation of ethylene to ethylene oxide at a given ethylene conversion that is higher than was possible with using conventional catalysts.

The phenomenon of obtaining higher selectivity using the catalyst according to the invention is not fully explained. However, it should be paid

083 Note that experiments with conventional silver (non-alkali metal) catalysts used in amounts according to the method of this invention show degradation of the ethylene oxide produced, while silver catalysts which are the subject of this invention, i.e. containing from 0.00035 to. 0.0030 girws per kilogram of co-deposited · alkali metals do not cause measurable degradation of ethylene oxide.

Example 1. Catalyst A is prepared by the process of the invention as follows. The "Alundum" class LA-5556 (Nicrton Company) is used as the carrier in the form of 8 mm diameter aluminum oxide rings. · This carrier contains 99.3 '% by weight of alpha aluminum oxide, 0.4% silica and 0.3 ° / other metal oxides and has a specific surface area of ​​0.24 m²/ g and apparent porosity of 48 to 49% by volume. The average pore diameter is · 4.4 microns according to the mercury method, and the 80 ° / pore diameter ranges from 1.5 to 15 microns.

The carrier is saturated with an aqueous solution of silver salt containing a certain amount of potassium. This solution is prepared as follows. Silver oxide (purity grade of reaction reagent) is mixed with an aqueous solution of oxalic acid (purity grade of reaction reagent) dissolved in ethyl diamine to give a 4 m solution · Ag₂/ EN / 2C2O₄ (EN stands for ethylene diamine) and 10% by volume of eftandoimine, i.e. about 0.4 litter ethanolate per mole of silver, is added in order to obtain a mixture dissolving the reducing agent. This solution contains approximately 22% by weight of silver. Potassium nitrate is added to it in such an amount that the concentration of potassium is 190 ppm by weight. The support is saturated with a silver solution containing potassium, vacuum being applied to ensure complete saturation. - Excess liquid is drained off and the carrier is immediately placed in an oven with a blow of air at 290 ° C in the face of drying the catalyst and reducing the silver salt to metallic silver. The total heating time is about 3 hours. The silver content in the catalyst was found to be 7.8% by weight, and the potassium content on the surface of the catalyst was 60 ppm by weight, i.e. 0.0015 grw of potassium per kilogram of catalyst.

The silver form deposited on the catalytic converter was examined by electron microscopy and found to be single particles with a homogeneous diameter from 0.2 to 0.4 microns, i.e. 2000 to 4000 A. These particles are evenly distributed on the external and internal surfaces of the carrier. Tests and shaking of the catalyst have shown that silver particles adhere strongly to the surface of the support.

In order to compare the methods of preparation of the catalyst described above, the catalyst was re-prepared, but no potassium was added to the solution used for saturation. Based on the analysis, it was found that there was no more than 5 ppm potassium in the solution. This catalyst (Ai catalyst) contains 7.8% by weight * of silver and has a physical microstructure similar to co-isotoro A.

The A and Ai catalysts were tested comparatively in the ethylene oxide production process. In a representative experiment, 8 mm catalyst rings A and 3.5 g 30/40 mesh crushed catalyst particles were ground into reactor tube 1 with a diameter of 5 mm and a length of 125 mm. A mixture of air and ethylene was passed through the catalyst bed in the presence of chlorine as a moderator under the following reaction conditions: pressure 1 atm. . abs., volumetric speed 3300 1god: zine, 30% molar ethylene content and moderator concentration 10 to 15 ppm calculated as chlorine.

The reaction temperature was selected so as to achieve 52% oxygen conversion and the selectivity of ethylene oxide preparation was tested.

Using catalyst A, 253 ° C was needed to achieve a standard 52% conversion, and the selectivity for obtaining ethylene oxide was 70%. For comparison, the selectivity of the Ai catalyst towards ethylene oxide is only 69%.

Example II Catalyst B is prepared in a similar manner to that described in Example 1 for catalyst A.

The carrier itself is saturated with an aqueous solution of potassium and silver salts prepared by another method. An aqueous solution of silver nitrate (purity grade of the reagent for the reaction) is mixed with an aqueous solution of potassium szazawiand with the same purity grade. The silver oxalate oisadium is collected and (thoroughly washed with deionized water until a potassium content of 8 ppm per 1% by weight of silver is reached. This potassium-containing silver oxalate then dissolves in an aqueous solution of ethylenediamine and is used to saturate the support as in Example 1. The finished catalyst contains 7.8% by weight of silver and 62 ppm by weight of simultaneously potassium.

For comparison, the same method is prepared with the catalyst Βχ except that the number of rinsing of silver oxalate is changed. The catalyst contains 310 ppm by weight of simultaneously added potassium.

When catalyst B is used in the ethylene oxidation reaction carried out as described in Example 1, the standard conversion is achieved at 253 ° C and the selectivity towards ethylene oxide is 78.6%. It was found that the Bi catalyst was not "active" in the ethylene oxide production process.

Example III. Using the general method of preparation of the catalyst and starting from the materials described in Example 1, a series of catalysts containing various amounts of potassium (both according to and according to the method of this invention) was obtained. Blends of these catalysts, each containing 7.8 ± 0.3% by weight of silver, are listed in Table II.

083

Table II

<td>catalogs lizator</td><td colspan="2">Alkali metal content</td><td>Oxidation selectivity to ethylene background,%</td>

<td></td><td>grw of alkali metal per kilogram of catalyst</td><td>ppm by weight potassium</td><td></td>

<td>cr</td><td> 0,00026</td><td> 10</td><td> 68,5</td>

<td>di</td><td> 0,00037</td><td> 14</td><td> 69,4</td>

<td>E_L</td><td> 0,00062</td><td> 24</td><td> 70,6</td>

<td>Fi</td><td> 0,00065</td><td> 27</td><td> 70,4</td>

<td>D</td><td> 0,0011</td><td> 42</td><td> 74,3</td>

<td>E</td><td> 0,0012</td><td> 44</td><td> 75,0</td>

<td>F</td><td> 0,0016</td><td> 63</td><td> 76,3</td>

<td>G</td><td> 0,0016</td><td> 64</td><td> 76,2</td>

<td>H</td><td> 0,0018</td><td> 72</td><td> 76,0</td>

<td>AND</td><td> 0,0021</td><td> 82</td><td> 73,3</td>

12 m under the following reaction conditions:. pressure 15.3 atm abs., temperature 245-260 ° C, volumetric speed 3300 1 // hour, ethylene content in the raw material 3C ° / o, ethylene-oxygen ratio 3.5, oxygen conversion 52 ° / o, optimal moderator concentration 11-14 ppm in converted to chlorine. The results of these experiments are expressed as the selectivity for oxidation to ethylene oxide. also given in table II.

Example IV Using the raw materials and the method described in Example 1, catalysts containing different amounts of rubidium as an alkali are prepared. Instead of potassium, rubidium nitrate is added to the solution used for saturation. The mixtures prepared in this way are tested as ethylene oxide reaction catalysts, in the apparatus and method described in Example 1. Characteristics of these mixtures and the results obtained with them in the oxidation process Table III

<td rowspan="2">Catalyst</td><td rowspan="2">Content silver% by weight</td><td colspan="2">Alkali metal content</td><td rowspan="2">Reaction temperature to achieve 52% oxygen conversion . ° C</td><td rowspan="2">Oxidation selectivity towards ethylene oxide yellow °</td>

<td>grw per kilo</td><td>ppm by weight rubidium</td>

<td>M</td><td> 7,8</td><td> 0,00068</td><td> 58</td><td> 254,0</td><td> 73,4</td>

<td>N</td><td> 7,8</td><td> 0,0011</td><td> 90</td><td> 257,5</td><td> 77,5</td>

<td>ABOUT</td><td> 7,8</td><td> 0,0015</td><td> 125</td><td> 249,0</td><td> 79,7</td>

<td>P</td><td> 7,8</td><td> 0,0018</td><td> 155</td><td> 258,5</td><td> 79,0</td>

<td>P '</td><td> 7,8</td><td> 0,0018</td><td> 155</td><td> 255,5</td><td> 79,5</td>

<td>Q</td><td> 7,8</td><td> 0,0021</td><td> 179</td><td> 263,0</td><td> 79,9</td>

<td>R</td><td> 7,8</td><td> 0,0021</td><td> 180</td><td> 260,0</td><td> 78,3</td>

<td>s</td><td> 7,8</td><td> 0,0029</td><td> 247</td><td> 286,0</td><td> 74,0</td>

<td>S '</td><td> 7,8</td><td> 0,0032</td><td> 273</td><td> 315,0</td><td> 67,4</td>

Table IV

<td rowspan="2">Catalyst</td><td rowspan="2">Content silver % by weight</td><td colspan="2">Alkali metal content</td><td rowspan="2">Reaction temperature to achieve 52% oxygen conversion ° C</td><td rowspan="2">Ethylene oxide oxidation selectivity οθ</td>

<td>grw per kilo</td><td>ppm by weight cesium</td>

<td>T</td><td> 7,8</td><td> 0,00042</td><td> 55</td><td> 248,5</td><td> 77,2</td>

<td>at</td><td> 7,8</td><td> 0,00061</td><td> 81</td><td> 256,2</td><td> 79,4</td>

<td>V</td><td> 7,8</td><td> 0,00066</td><td> 88</td><td> 256,0</td><td> 80,0</td>

<td>in.</td><td> 7,8</td><td> 0,00068</td><td> 90</td><td> 262,5</td><td> 79,3</td>

<td>X</td><td> 7,8</td><td> 0,00071</td><td> 95</td><td> 251,0</td><td> 79,8</td>

<td>X</td><td> 7,8</td><td> 0,00071</td><td> 94</td><td> 252.0</td><td> 79,8</td>

<td>Y</td><td> 7,8</td><td> 0,00074</td><td> 96</td><td> 256,0</td><td> 80,0</td>

<td> ¥'</td><td> 7,8</td><td> 0,00074 ·</td><td> 97</td><td> 257,0</td><td> 80,3</td>

<td>FROM</td><td> 7,8</td><td> 0,00079</td><td> 105</td><td> 252,0</td><td> 81,0</td>

<td>FROM</td><td> 7,8</td><td> 0,00079</td><td> 105</td><td> . 257,5</td><td> 80,2</td>

<td>FROM</td><td> 7,8</td><td> 0,00079</td><td> 105</td><td> 254,5</td><td> 79,6</td>

<td>AA</td><td> 7,8</td><td> 0,00081</td><td> 108</td><td> 247,0</td><td> 79,5</td>

<td>BB</td><td> 7,8</td><td> ’ 0,0012</td><td> 157</td><td> 261,5</td><td> 78,2</td>

<td>CC</td><td> 7,8</td><td> 0,0016</td><td> 208</td><td> 273,5</td><td> 76,2</td>

<td>DD</td><td> 7,8</td><td> 0,0020</td><td> 265</td><td> 325,0</td><td> 65,2</td>

for ethylene oxide are shown in Table III above.

Example V. Using these raw materials and each of these catalysts was tested over a longer period of time in a pilot reactor for the production of ethylene oxide with a diameter of about 45 mm and for a long time using the catalyst described in Example 1, catalysts containing different amounts of cesium as an alkali are prepared. Instead of potassium, cesium is added in the saturation solution as cesium nitrate. The mixtures prepared in this way are tested as oxidation catalysts for ethylene oxide, in the apparatus and method described in Example 1. The characteristics of these mixtures and the results obtained using them as oxidation catalysts for ethylene oxide are presented in Table IV above.

Example VI (for comparison). Two groups of catalysts were assembled using the same raw materials and by the method described in the example

I. One group of catalysts contained. different amounts of sodium and the other different amounts of lithium.

All these catalysts contained 7.8% by weight of silver and from 0.0001 to 0.002 grw per kilogram of lithium or sodium catalyst.

These catalysts were tested in the ethylene oxidation reaction using the same apparatus and method described in Example I. Within the confines of the error of experiment, no improvement in catalyst selectivity was observed.

Example VII (for comparison). Using the method described in Example 1, a catalyst containing at most 5 ppm by weight of simultaneously deposited potassium and 7.8% by weight of silver is prepared. This catalyst, tested in the ethylene oxidation reaction, shows 69% selectivity. Samples of this catalyst were treated with aqueous potassium solutions, thereby adding various amounts of potassium. Even with the introduction of 0.00090 to 0.0022 grw per kilogram of catalyst, an improvement in selectivity was observed, by a maximum of 4-5%, i.e. 73-74%.