SE434837B - PROCEDURE FOR THE PREPARATION OF ETHYLENOXIDE BY DIRECT OXIDATION OF ETHEN IN ANGASE PHASE WITH MOLECULATED ACID IN THE PRESENT OF A SILVER CATALYST - Google Patents

Description

.78ßä959-5 2 % by weight of an inorganic halide (sodium chloride or preferably potassium chloride) are added as separate solid particles to a fluidized bed of a carrier-deposited silver catalyst lysator, the halide acts as a damping agent and inhibits depends on the activity of the catalyst. In U.S. Pat. No. 3,144,416 lists a number of promoter materials, but some critical constraints on their concentration are indicated not. The use of alkali and alkaline earth metals as engines are generally described in U.S. Pat 3,563,913, which specifically states lithium but does not contain any reference to cesium, rubidium or potassium. These pro- engines are preferably added to the catalyst support before the latter is impregnated with the solution containing silica association. The use of alumina supports with a porcelain volume between 0.15 and 0.30 m2 / g and a surface area below 10 m2 / g disclosed in U.S. Patent 3,575,888 of certain organic amine solubilizing / reducing agents for preparation of evenly distributed, adherent hemispheric deposits of metallic silver on catalyst supports are given in U.S. Pat. No. 3,702,259. If patent application 7300162, catalysts can be used, containing one or more of the alkali metals potassium, ru- bidium and / or cesium in an amount of 0.35-3.0 milligrams more alkali metal (mgat) per kg of catalyst, which metals has been deposited simultaneously with the silver on the catalyst support.

Addition of potassium, rubidium and / or cesium in amounts for the specified interval is not favorable and the addition of alkali before the addition of silver gives little or no advantage.

The state of the art thus shows that the addition of alkali pine compounds change, for better or worse, the nature of a silver ethylene oxide catalyst.

It has now been found that the deposition of potassium, rubidium or cesium before the deposition of the silver in critical amounts, as are proportional to the surface area of the support, give superior ethylene oxide catalysts. '7808959-6 3 The invention thus relates to a method for production of ethylene oxide by direct oxidation of ethylene in the vapor phase with molecular oxygen in the presence of a silver which comprises silver and one or more alkali compounds. on a porous refractory support, the process is marked by performing the procedure using a silver catalyst, which has been prepared by a process, which means that one a) impregnates a porous, refractory support with a surface area of 0.03-10 mg / g with a solution of a compound of an alkali metal with an atomic number of 19-55 in such a concentration that optionally after extraction with a solvent after either steps b) or c) below, in the finished catalyst reaches a content of 0.25-16 mg equivalent weights of the alkali metal per kg total catalyst for each m2 of support area per gram catalyst support (mg / kg) / (m g); b) at least partially dries the impregnated support from step a); c) brings the product from step b) into contact with a liquid phase, which contains a dissolved silver compound or a dissolved slurrying of particles of silver or a silver compound in an amount sufficient to deposit 1-25% by weight silver, calculated on the total catalyst, on the support surface and d) thermally treating the product from step c) for conversion of the silver compound to silver metal.

The catalysts used in the present invention comprises a porous, refractory support, on the outside and inside of which (pore) surfaces 1-25% by weight, based on the total catalyst, silica and certain amounts of potassium, rubidium and / or cesium are set aside. Of the alkali metals, ie lithium, sodium, potassium, rubidium and cesium, only the alkali metals are included atomic numbers from 19 to 55suitable, ie potassium, rubidium and cesium. Unless otherwise stated, these 3 suitable metals are meant hereinafter when the term "higher alkali metals" is used.

Excellent results are obtained with each of the three higher alkaloids. the limetals. Potassium provides benefits from a cost point of view, though cesium provides the greatest catalyst improvement. Rubidium ger - - ~ _..._....-..._.-..._..._.__-._.__._._..., 7808959- * 6 4 a greater catalyst improvement than potassium. Mixtures of the higher alkali metals are also useful.

The higher alkali metals are present on the catalysts in form of their cations, rather than as the extremely active ones the free alkali metals. Silver on the other hand is present at the finished catalysts such as silver metal.

The amount of higher alkali metal (or metals) present in the on the catalyst surface, is a critical function of the surface area.

The content of higher alkali metals has been shown to be directly proportional. relative to the surface area of the carrier, the optimum content being is generally 5: 4 and in particular 5-3 mg equivalent weights per kg of total catalyst for each mg of surface area per gram of catalyst carrier (mgev / kg) / (m2 / g). The optimum content of higher alkali pine, divided by the surface area, has in other words approximately a constant value. It has been found that, when alkali metal the content is increased from 0, the selectivity of the catalyst increases to one maximum and that at concentrations above this maximum the teten again decreases. The level at which this maximum the selectivity appearing is hereinafter referred to as "the optimum alkali metal content" of the optimal selectivity takes place gradually rather than alkali metal levels are both above and below the opti- grinding value, which also provide commercially significant improvements in catalyst selectivity and which also falls within the scope of the present invention. Alkali metal the contents consequently preferably comprise contents which: varies from 25-175% of the optimal content, especially 25-150% and in particular from 50-150% of the optimum content.

Expressed as a technically feasible range, the content is higher alkali metal, relative to the support area, 0.25-16, preferably 0.25-14 and in particular 0.5-14 mg equivalent weights per kg total catalyst for each m2 surface area per gram catalyst support (mg / kg) / (m2 / g). It seems to exist minor variations in the content range for each of the higher alkali metals of the present invention, wherein optimal selectivity is achieved when the catalysts are used 7808959- * 6 5 in the partial oxidation of ethylene to ethylene oxide according to the invention ningen. However, it is assumed that these minor differences are to attribute to indefinite experimental differences el- other unknown variables, but they are not considered significant edge. Although the optimum content of alkali metal is directly pro- proportional to the surface area of the catalyst support not all surface areas are commercially useful catalysts. Ka- talysatorium areas, which have been shown to be critical for is 0.03-10 m2 / g.

It must be made clear, that the amounts of potassium, rubidium and / or cesium not necessarily deposited are the total quantities of these metals present in the catalyst torerna. They are the amounts of these alkali metals that are present on the surface of the catalyst and intentionally placed to the catalysts before the addition of silver. It's not unusual to significant amounts, often up to 1% by weight, of higher alkali metals (usually potassium) are present in it porous support, due to the use of support material, containing naturally occurring alkali metals, or as a result of an accidental addition of alkali metal during the the position of the wearer. These amounts of higher alkali metals, which is present in the carrier in non-leachable form, appears not contribute to the improved performance of those under the present invention use the catalysts and are neglected in the determination of alkali metal concentrations. Lots of higher alkali metal, which is present in the carrier in leachable form, however, must be taken into account when determining the quantities of higher alkali metal deposited on the support. In fact constitutes an alternative method of providing all or part of the desired amount of higher alkali metal to be introduced livens the higher alkali metal with the carrier in leachable form during the manufacture of the carrier.

The catalysts used in the present invention include contains 1-25% by weight, based on the total catalyst, silver such as silver metal. Preferably they contain 2-20 and i especially 4-16% by weight of silver. The use of silver quantities fiâ08959 “6 6 exceeding 25% by weight is not excluded but is generally economical nomically unattractive. The silver is deposited over the catalyst support inner and outer surfaces and should be evenly distributed over these surfaces.

The exact physical shape of the silver on the carrier can vary and does not appear to be critical to the invention. Very excellent results are achieved, however, with the methods of the present invention. use the catalysts with a controlled surface alkaline glued metal, when the silver is present in the form of evenly distributed, discontinuous, adherent separate particles with a unitary diameter of less than 1 micron (10,000 Å). The best re- the results are obtained with this type of catalyst, as the silver have diameters of 1000 to 10,000 Å and the most common the drawn catalysts have silver particles with a average diameter in the range 1500-7500 Å.

The carrier used in the catalogs used according to the invention The lysers are selected from the large number of conventional, hot, refractory catalyst supports or support materials that are substantially inert to the ethylene oxidation starting materials, the products and the reaction conditions. Such conventional materials can have natural or synthetic origin and have preferably a macroporous structure, i.e. a structure with a surface area below 10 m2 / g and preferably below 7 m2 / g. These carrier materials usually have an apparent porosity of more than 20%.

Very suitable carriers include silicon-containing and / or aluminum minium-containing ones. Specific examples of suitable carriers are the aluminas (including the materials marketed under trade name "Alundum"), charcoal, pumice, magnesium oxide, zirconia nium oxide, diatomaceous earth, full earth, silicon carbide, porous agglomerates including silicon and / or silicon carbide, magnesium oxide, clays, synthetic and natural zeolites and ceramic materials rial. Refractory supports, which are especially useful in the status of the catheters used in the present invention lysers, include aluminum-containing materials, in particular hot ones containing G-alumina. Regarding a = alumi- nia oxide-containing supports are preferred those with a specific surface area, measured by the B.E.T. method, of 0.1-7 m 2 / g and an apparent u-a 78Û8959 ~ 6 7 porosity, measured by conventional mercury or water absorption technique, of 10-50% by volume, the B.E.T. method for determination of the specific surface area is described in detail by the nauer S., Emmett P.H. and Teller E. in J. Am. Chem. Soc. §Q (1938) 309-319.

Regardless of the nature of the carrier used, it is shaped to particles, pieces, pellets, rings, spheres and the like with a size suitable for use stationary bed systems. Conventional, commercial stationary bed ethylene oxidation reactors are usually present. gene in the form of a plurality of parallel, long tubes (in a suitable häje) reaches a diameter of about 2.5-5 cm and with a length of 7-14 meters and which are filled with catalyst. In such reactors are it is desirable to use a carrier which has a rounded shape, such as spheres, pellets, rings, tablets and the like, and which have a diameter of 2.5-20 mm.

The exact concentrations of higher alkali metal compounds and silver compounds used in the above step (a) and (c) using the impregnation solution may generally require some experiments of a routine nature, because the amount set aside is higher alkali metal compounds and silver compounds are partially dependent of the porosity and surface area of the catalyst support. Ways to vary the deposited amount of higher alkali metal and silver is conventional as well as the analytical determination of the amount of material actually present.

Preferably, the impregnating liquid in step (a) above contains the higher alkali metal compound in such a concentration that one in the final product achieves a content of higher alkali metal of 0.25-14 and in particular 0.50-14 mg equivalent weights per kg of total lysator for each m2 of support area.

Another procedure involves depositing larger quantities than required by the higher alkali metal salts of step (a) in the general procedure described above, after which brings the catalyst particles thus obtained, either 7808959-6 8 after step (b) or step (d) of the process described above, i contact with a suitable solvent, e.g. an anhydrous alkanol having one or two carbon atoms per molecule, methyl or ethyl acetate or tetrahydrofuran. The higher alkali metal salts are soluble in the solvents described in such an embodiment. to the extent that one or more washes with these solutions means will selectively remove the excess higher alkali metal, so the amount that remains intact on the support surface will be within the critical range of the invention tration interval. This procedure therefore provides a simple way to regulate the concentration of higher alkali metal from levels exceeding 16 (mg / kg) / (m2 / g) either this content is the result of intentional or unintentional measures, to specific concentrations within the range 0.25-16 (mg / kg) / (m2 / g) by a method which can be easily suitable for large-scale operation.

An excellent method of adding the desired higher alkali metal is to dissolve a compound thereof in an aqueous phase in a amount, which is regulated to give the required alkali metal content in the finished catalyst, when the support is brought into contact therewith.

Suitable higher alkali metal compounds generally include all those that are soluble in an aqueous phase. In this regard, can one does not find any unusual. efficiency when using there is a special anion in the alkali metal compounds. So e.g. hydroxides, nitrates, nitrites, chlorides, iodides, bromides ter, bicarbonates, oxalates, acetates, tartrates, lactates and isopropoxides can be used. The carrier can after impregnation with the higher alkali metal is dried in any suitable manner, preferably by raising the temperature to between 100 ° C and 2D0 ° C, e.g. for a period of 0.5-8 hours and 0.5-4 hours, with multiple temperatures being appropriate. and an inert gas is passed over the heated carrier.

Suitable inert gases are nitrogen, air, hydrogen, noble gases, carbon dioxide oxide, methane and mixtures of these gases. The drying can performed at atmospheric pressure, negative pressure or overpressure.

Vacuum and freeze drying can also be used to advantage. One 7809959-'6 9 Various methods of adding silver to carriers are known.

In a typical process, the support is impregnated with an aqueous solution of silver nitrate and dried, after which the silver is reduced. with hydrogen or hydrazine, as described in U.S. Pat U.S. Patent 3,575,888. According to another technique, impregnation the carrier with an ammoniacal solution of silver oxalate or carbonate and then the silver metal is formed by thermal decomposition of the salt. The silver can also be added by means of the technology described in U.S. Pat 3 702 259, according to which the carrier is impregnated with special aqueous solutions of silver salts and combinations of ammonium ak, vicinal alkanolamines and / or vicinal alkyldiamines and then thermally treated. Other possible methods for addition of silver involves impregnating a support with an ethanolamine-containing solution of a silver salt and thereafter reduction, as described in Japanese Pat. 19606/1971, or by adding a slurry of fine particles of silver carbonate to the support and thermal decomposition, such as U.S. Patent 3,043,854, or by the addition of silver in the form of cluster silver as is written in U.S. Pat. No. 3,781,317 and one of these methods is put silver to the wearer, then the wearer brought into contact with a liquid phase, which contains either a silver solution or a slurry of silver particles or a silver compound.

A particularly effective method of depositing the silver means that the silver is added to the support from a basic solution, in particular from a nitrogenous alkaline solution. Examples of these nitrogen bases are ammonia, the alkylamines and the alkanolamines.

In the case of a particularly preferred modification, the addition of silver to the catalyst support by the technique described in U.S. Patent 3,702,259 manufacturing method involves impregnating an aluminum oxide support with certain aqueous solutions of silver salt and a subsequent thermal reduction of the silver salt. Silverim- the impregnation solution mainly consists of: 7808959-6 10 A. a silver salt of a carboxylic acid B. an alkaline solubilizing / reducing agent in the form of an organic amine and C. an additional aqueous solvent, if required in order to achieve the desired silver content.

Suitable carboxylic acid silver salts include silver carbonate and the silver salts of mono- and polyhydric carboxyl and hydroxy carboxylic acids having up to 16 carbon atoms per molecule. Silver- carbonate and silver oxalate are especially useful silver salts, with silver oxalate being particularly preferred.

A solubilizing / reducing agent in the form of an organic amine is present in the impregnation solution used in this method of production. Suitable silver solubilizing / re- reducing agents in the form of organic amine include lower alkyl lendiamines with 1-5 carbon atoms per molecule, mixtures of a lower alkanolamine having 1-5 carbon atoms with a lower alkylenediamine with 1-5 carbon atoms as well as mixtures of ammonia with lower alkalis canolamines or lower alkylenediamines having 1-5 carbon atoms. Fy- groups of solubilizing / reducing agents in the form of ganic amine is preferred. These are the following: A. vicinal alkylenediamines having 2-4 carbon atoms; B. mixtures of (1) vicinal alkanolamines having 2-4 carbon atoms and (2) vicinal alkylenediamines having 2-4 carbon atoms; C. mixtures of vicinal alkylenediamines having 2-4 carbon atoms and ammonia; and D. mixtures of vicinal alkanolamines having 2-4 carbon atoms and ammonia.

These preferred solubilizing / reducing agents are added in generally in an amount of 0.1-10 moles per mole of silver present.

Particularly preferred solubilizing / reducing agents are: A. ethylenediamine, B. ethylenediamine in combination with ethanolamine, '7808959-6 11 C. ethylenediamine in combination with ammonia and D. ethanolamine in combination with ammonia.

Ethylenediamine, alone or in combination with ethanolamine, drawn in particular.

When ethylenediamine is used as the sole solubilizing / reducing agent means, it is necessary to add amine amounts of 0.1 ~ 5.0 moles of ethylenediamine per mole of silver.

When ethylenediamine and ethanolamine are used together as solu- mobilizing / reducing agents it is appropriate to use 0.1-3.0 moles of ethylenediamine per mole of silver and 0.1-2.0 moles of ethanol amine per mol silver.

When ethylenediamine or ethanolamine is used with ammonia, it is in generally appropriate to add at least 2 moles of ammonia per moles of silver and especially suitable to add from about 2 to about 10 moles of ammonia per mole of silver. The amount of ethylene used diamine or ethanolamine is suitably 0.1-2.0 moles per mole of silver.

As mentioned above, it is essential that only certain controls amounts of the higher alkali metals of the invention are present, these amounts being a function of catalytic the surface area of the dry carrier. These amounts are achieved either by control. addition of alkali metal to the support in the first impregnated step or by controlled removal of excess alkali metal from the impregnated catalyst support, things before or after the silver impregnation step.

The thermal treatment according to step (d) can be performed at a temperature of 100-500 ° C, preferably up to 37500 and i especially of 125-325 ° C, for a time, usually 0.5-8 hours, required to decompose the silver salt and form the adhesive, particulate deposit of metallic silver on the surfaces. Lower temperatures do not decompose the silver salt ade- and should therefore be avoided. More than one temperature can be used.

The silver catalysts, which contain the promoters of higher '7808959-6 12 alkali metal, have been found to be particularly selective catalysts in the direct oxidation of ethylene with molecular oxygen to ethylene oxide according to the invention. The conditions for such an oxidation reaction in the presence of silver catalysts. the lysators of the present invention generally include the conditions used according to the state of the art. This applies to e.g. temperature, pressure, residence times, dilution materials such as nitrogen, carbon dioxide, water vapor, argon, methane or other saturated hydrocarbon, the presence or absence of moderate agents in order to control the catalytic effect, for example 1,2-dichloroethane, vinyl chloride or chlorinated polyphenyl compounds, the desirability of using recycling procedures or to use successive conversions in different reactions in order to increase the yields of ethylene oxide and any other, special conditions that can be selected in procedures for the production of ethylene oxide. Press within the range from approximately atmospheric pressure to about 35 bar absolute pressure is used in public. However, higher pressures can be used within the framework of the invention. The molecular oxygen used as the reactant obtained from conventional sources. The oxygen reactant can be constituted of essentially relatively pure oxygen, a concentrated oxygen stream, which comprises a larger amount of oxygen and smaller amounts of one or several diluents, such as nitrogen, argon, etc., or any other oxygen-containing stream, such as air. The use of the the new silver catalysts in ethylene oxidation reactions are not in any way limited to the use of specific conditions among those known to be effective.

In a preferred embodiment according to the invention ethylene oxide by an oxygen-containing gas containing at least 95% oxygen, is contacted with ethylene in the presence of the present catalysts at a temperature in the range 210-285 ° C and preferably 225-270 ° C.

The resulting ethylene oxide is separated and recovered from the reaction. products by means known in the art and used conventional methods. The use of the new silver catalysts The yields of ethylene oxide production according to the invention give higher 7808959 “6 13 total ethylene oxidation selectivities with respect to ethylene oxide at a given degree of ethylene conversion than is possible with conventional catalysts.

Although the reasons for the higher selectivities observed with the catalysts used in the present invention are not fully clarified, experiments have shown that conventional silver catalysts (which do not contain higher alkali metals) causes ethylene oxide to burn after formation while silver catalysts, which contain higher alkali metals according to religious invention, does not give rise to an equally comprehensive ethylene oxide combustion. The invention is further illustrated by the following embodiments. examples, in which the temperatures refer to degrees Celsius.

Example 1 A series of catalysts were prepared using alumina. nia oxide support with different surface areas. The physical properties in these carriers are given in Table I below.

Table I Catalyst support A B C D E Brand Name - Carborundum Norton Girdier Pêchíney SAHT-96 Company SRS 6 LA-4102 Yuma, m 2 / g 0.19 0.51 1.07 1.32 6.55 Particulate rings spheres, cyindrines, spheres, 8 mm diam. rar, diam. diam. 5 mm diam. 15 nm 2-5 mm 5 mm Sodium shale, weight% 0.02 0.013 0.24 0.40 0.52 Zinc content, weight% - - 0.24 0.23 - Silica content, weight% 0.26 2.37 0.15 0.28 2.5 Iron haite, weight% 0.09 0.45 0.04 0.03 0.05 0.05 Other track metals than Na, Zn, Si and Fe, wt% oxides 0.33 0.85 0.25 0.3 0.3 Apparent porosity from water absorption tion, vo1% 24 50 25 25 40 78Û8959 “6 14 Table I (continued) Catalyst support A B C D E Average pore diameter, micron 3.9 2 0.8 0.6 0.25 80% of the pears had diameters within interval (microns) 1.5-15 0.3-10 0.4-1.2 0.2-1.5 0.1-0.9 Pore volume determined by partly mercury- rosimeter, m1 / g 0.23 0.25 0.22 0.45 Catalysts, designated A-1, A-2, ..., B-1, etc. were prepared in accordance with the present invention, i.e. by disposal of the alkali metal and the silver. Catalysts, designated NA-O, NB-O, ... NI-O, etc., were not according to the invention because they did not contain any alkali metal. Catalysts, cartoon NA-1, NA-2, ..., NB-1, etc, were also not in accordance with the present invention because the deposition of alkali metal the pine and the silver were made at the same time.

The preparation of catalysts in accordance with the present invention invention is illustrated below by reference to the preparation catalysts, prepared with support C. The others the catalysts of the present invention were prepared on similar way. 30 g of carrier C with a surface area of 1.07 m 2 / g were first impregnated under a pressure of 0.04 bar abs. in a rotary evaporator with 8.5 ml of an aqueous solution containing 3 mg of cesium hydroxide per ml of solution. The impregnated support was dried by heating for 30 minutes at 110 ° and then for 2 hours at 1500 ° in a stream of nitrogen.

The support was then impregnated with an aqueous solution of silver salt. This solution was prepared by the following techniques. 6 g anhydrous silver nitrate and 3.3 g potassium oxalate (K2C2O4.1 H2O) was dissolved separately in 100 ml portions of water. The solutions obtained The mixtures were mixed and heated on a steam bath. Silver oxalate the precipitate was centrifuged and the supernatant was am ... 7808959-6 15 edged. Then the precipitate was washed 5 times with 100 ml of warm (60-900) distilled water. Precipitation Centrifu- and the water was decanted after each wash. Pre- The precipitate was then dissolved in 10 ml of a mixture which consisted of 75% by volume of 1,2-diaminoethane and 25% by volume of water, wherein the mixture is cooled in ice. 30 g of the cesium-containing The reactor was then impregnated at a pressure of 0.04 bar abs. in a rotary evaporator with 8.5 ml of the latter liquid, was heated by indirect heat exchange with hot water to a temperature of 600 during rotation, again at 0.04 bar abs. for partial removal of the solvent, was poured onto a large filter paper and was gently shaken to remove any excess moisture, heated in a stream of nitrogen for 2 hours until a temperature of 3000 was reached and kept at 3000 for another 2 hours. The catalyst is cooled then to ambient temperature. Catalyst silver content was 7.8% by weight. The cesium content amounted to 3.35 mg / kg catalyst. Examination of the catalyst with an electron micrometer roscope revealed that the silver had been deposited on the carrier as ready particles with a uniform diameter of 0.05 to 0.3 micron (500-3000 Å). The silver particles were evenly distributed over the wearer's surface.

For the preparation of NA-O-, ..., NI-O series of catalysts, which did not contain any alkali metal, the above-described the first impregnation step with the cesium hydroxide solution, wherein the subsequent steps were essentially the same.

For the preparation of the NA-1, NA-2, ..., NB-5 series of catalytic which were not in accordance with the invention were omitted also the first impregnation steps with cesium hydroxide described above the. The subsequent steps were followed in a substantially similar manner except that the cesium hydroxide was added to the silver -ethylenediamine aqueous solution in sufficient amounts to give the desired alkali metal content in the finished catalyst product ten.

The catalysts prepared above were subjected to comparative testing '? 8Û8959 "6 16 with respect to the production of ethylene oxide. The reactor constitutes was made of a tube with an inner diameter of 5 mm and was in each experiments filled over a length of 12 cm with catalyst particles, whose dimensions were in the range 0.4-0.8 mm. These categories lysator particles were obtained by grinding those on the top coat prepared catalyst particles.

A mixture containing oxygen and ethylene was passed through lysator bed in the presence of a small amount of vinyl chloride such as moderator under the following conditions: Pressure ... 14.5 bar abs. volume rate. . . saoor fl Ethylene in starting material ... 30 mol% Oxygen in starting material ... 8.5 mol% Nitrogen in starting material ... 61.5 mol% Moderator conc., In volume million- parts of the starting material 10 ppm The reaction temperature was adjusted to obtain an oxygen concentration. conversion of 52% and the selectivity to ethylene oxide was determined. The selectivity with respect to ethylene oxide, expressed in%, is defined as the number of moles of ethylene oxide formed by 100 moles of converted ethylene. The results of the experiments described above are shown in Tables II-VI. As shown in these tables provides the stepwise deposition method of the present invention at the smallest bearing surface areas used similar results as the method of simultaneous disposal. With the carriers with the desired larger surface area gives the technique of the present invention ka ~ catalysts which are far superior to those of catalysts which do not have been prepared in accordance with the present invention. 7808959'6 17 Table II Catalysts prepared with supports with surface areas of 0.19 m2 / g Egëíg fi hâlš Reaktortemp. Oxidation disease Silver- weight miijen- for uppn. of the fine with respect to Cat. hait mgev / kg deiar 32% 02-conv., on ethylene oxide, 2 C A-1 *) 7.0 0.86 114 259 79.9 A-2 7.6 1.01 134 255 80.3 A-3 7.9 1.11 148 259 80.7 A ~ 4 7.6 1.49 198 265 79.8 A ~ 5 8.2 1.65 220 261 79.0 NA-0 7.8 0 0 251 69.5 NA-1 8.3 0.77 103 254 80.3 NA-2 8.3 1.08 143 258 80.6 NA-3 7.7 1.25 166 263 80.2 NA ~ 4 7.8 1.64 218 264 79.7 NA-5 8.0 1.89 252 295 76.1 *) A-1, A-2, ..., B-1, etc., catalysts are produced in accordance with the present invention. invention.

NA-0, NB-0, etc., are catalysts which are not produced in accordance with the present invention. present invention and without a1k1imeta11ti11sats.

NA-1, NA-2, ..., NB-1, etc., are catalysts which are not produced according to the present invention without being prepared by simultaneous deposition of a1ka1imeta11 and siïver.

Table11 III Catalysts made with carriers with surface areas of 0,51 m2 [g] Cesium Hait Reactor Temp. for 0xadationse1ekti- . _ - _ - _uppn. of 2% penalty with para. pâ Cat. âaI ¥ er mgev / kg deI:? 11J0n 02 '° mV' ”äc etyïenøxïd '% ß-1 *) 7.7 0.89 118 254 74.5 B-2 7.9 1.53 204 252 77.8 B-3 7.7 2.79 371 258 78.2 B-4 7.5 3.77 502 259 76.5 B-5 7.9 5.50 732> 300 70.4 NB ~ 0 7.7 0 0 251 71.0 NB-1 7.1 2.64 351 261 77.6 NB ~ 2 7.4 3.78 503 274 76.1 NB-3 8.0 5.47 728> 300 64 Ü see footnote *) in tabe11 II 7808959-6 18 Table11 IV Catalysts are provided with carriers with surface areas of 1.07 m2 / g Cesium Hait Reactor Temp. for Dxidation Selective Siïver- V1ktm11- uppn. of ä2% tet with avs. on Cat. hait mgev / kg jondeïar 02-conv., C ethylene oxide,% c-1 Ü 8.4 1.56 208 237 77.7 C-2 8.8 3.52 468 249 78.4 C-3 10.7 6.03 802 255 79.5 C-4 8.7 6.59 877 256 77.5 C-5 10.6 7.95 1058 268 76.4 NC-0 8.0 0 0 260 71.9 NC-1 8.0 1.87 249 6 251 75.1 NC-2 8.0 3.11 430 260 75.9 NC-3 8.4 4.08 543 252 76.2 NC-4 9.2 4.80 639 257 74.7 NC-5 8.0 5.43 722 320 67.8 * Ü se fame: *) i 'manen 11. 5 Tabeïï V Catalysts produced with carriers with surface areas of 1.32 m2 / g I Cesiumhaït Silver- V1Etm11- Reactor temp. for Oxidation Selection Cat. haït mgev / kg jondeïar uppn. of 32% tet with avs. pâ O2 conversion, C ethylene oxide,% k), D-1 6.6 4.19 557 260 67.0 D-2 6.0 6.35 844 265 73.2 0-3 6.9 7.69 1024 264 75.4 D-4 7.2 9.56 1272 261 74.3 ND-0 5.4 0 0 257 66.0 ND-1 5.4 4.08 543 293 65.6 ND-2 5.4 4.69 624 289 63.2 Ü se fotnaf fl taben n.

Tabe11 VI Catalysts prepared with supports with surface areas of 6.55 mz / g Cesium content Reactor temp. for Oxidation Síïver- V1Etm11- uppn. of 32% fined with para. on Cat. content mgev / kg jondeïar 02-conv., C ethylene oxide,% *> E-1 11.5 25.7 3420 207 73.3 E-2 11.0 35.3 4690 205 75.4 E-3 11.2 39.5 5250 205 75.1 NE-0 9.4 0 0 220 50.0 NE-1 11.9 42.3 5621 277 42.4 'k see footnote *) 1 table II. 7808959-6 19 The above results are also shown in the attached diagram, where the cesium contents of the catalysts in ppm are deposited along it horizontal axis and the selectivities with respect to ethyl lenoxide in% along the vertical axis. The selectivities of the catalysts, prepared from the five listed in Table I. different aluminas, are shown in the diagram with five different symbols. The five curves, based on each set of sym- bulbs, represent selectivity as a function of cellular the content of the surface area indicated by each curve. The four the curves for the surface areas 0.19, 0.51, 1.07 and 1.32 m2 / g are based itself on the left and lower scales, while the curve for the surface area 6.55 m2 / g is based on the left and upper scales. The vertical arrows pointing to each of the five curves indicates the optimal cesium content for each of the five the catalysts. These optimal cesium levels are given in the table VII below.

Table VII Alumina, Optimal cesium- Selectivity Optimal cesium- yšarea, content at optimal content divided m / g mgev / kg cesium content, with surface area 2 % (mgev / kq) / (m / g) 0.19 1.12 80.7 5.9 0.51 2.26 78.4 4.5 1.07 -6.02 79.5 5.6 1.32 _ 8.13 75.5 6.1 6.55 35.7 75.4 5.4 Example II Catalysts in accordance with the present invention, which include contained varying amounts of potassium such as higher alkali metal components. was prepared using the starting material and the general preparation methodology of Example 1. Instead to add cesium to the first impregnation solution potassium was added as potassium hydroxide. Catalyst Composition The compounds prepared in this way were tested as ethylene oxide catalysts using the apparatus and technology Example 1. The composition of these catalysts together with the results obtained are given in Table VIII below. 7808959-6 20 Table VIII Catalysts prepared with supports with surface areas of 0.19 m2 / g Potassium content Reactor temp. Oxidation Weight- for uppn. of lectivity with Silver- million- ä2% 02-conversion, regarding Cat. content mgev / kg parts C ethylene oxide,% F-f) 7.8 1.74 to 256 79.8 NF-0 7.8 0 0 251 69.5 *> see footnote *) in Table II.

Example III Catalysts in accordance with the present invention, which contained varying amounts of rubidium such as higher alkali metal component, was prepared using the starting material and the general preparation methodology of Example I. I instead of adding cesium hydroxide to the first im- the impregnation solution was added rubidium as rubidium hydride oxide. The catalyst compositions thus prepared were tested as ethylene oxide catalysts using the apparatus and technique of Example 1. composition together with the results obtained are given in Table IX below.

Table IX Catalysts prepared with supports with surface areas of 0.19 m2 / g Rubidium content Reactor temp. for Oxidation Se- Weight achievement of 52% sectivity with Silver- nüljon- 02 conversion, regarding Cat. content mgev / kg parts OC ethylene oxide,% *> G-1 7.8 1.06. 90 252 76.7 NG-0 7.8 0 0 251 69.5 *) see footnote *) in Table II.

Example IV A series of catalysts were prepared in the same manner as described white in Example I, starting from the carriers listed in Table I. B, C, D and E but using cesium nitrate instead for cesium hydroxide. Catalysts A, F, K and P, which do not x contained cesium, was incorporated into Table X below in the 7808959-6 21 purpose. The catalysts were those given in Table X below the properties. The prepared catalysts were subjected to a comparative test for the production of ethyl lenoxide in stationary bed. The reactor consisted of a tube with an inner diameter of 5 mm and was filled over in each experiment a length of 16 cm with catalyst particles, the largest of which dimensions varied between 0.4 and 0.8 mm.

A mixture containing oxygen and ethylene was passed through lysator bed in the presence of a small amount of 1,2-dichloroethane such as moderator under the following conditions: pressure ... 14.5 bar abs. volume speed ... 3000 h 1 ethylene in starting material ... 30 mol% oxygen in starting material ... 7.8 mol% nitrogen in starting material ... 62.2 mol% moderator concentration in weight million ~ parts chlorine of the starting material 1.5 ppm The reaction temperature was set to give an oxygen conversion of 40% and the selectivity with respect to ethylene oxide des. The values S40 and T4O thus obtained are given in bell X together with the number of hours of operation a moment.

Table X Try Surface area at Silver- Cesium content Diam. at Drift, aluminiEm ~ halt, hos kat., silverpar- tim- No. Cat. oxide, m / g wt% mgat / kg tiklar, S40, E 0 mar micron% 6 1 A 0.51 12.8 0 0.1-0.4 76.3 214 100 2 B **) 0.51 12.1 0.72 0.05-0.5 78.7 220 95 3 C **) 0.51 9.4 1.07 0.1-0.6 79.0 235 120 4 D 0.51 11.0 1.24 0.1-0.6 79.0 235 *) 120 5 E 0.51 9.6 1.30 0.05-0.4 79.0 222 65 6 F 1.07 9.7 0 0.1-0.4 75.4 210 40 7 G 1.07 8.5 0.32 0.05-0.3 75.9 210 115 8 H 1.07 8.4 0.68 0.1-0.3 76.3 209 117 9 I 1.07 9.0 2.21 0.1-0.4 80.6 209 75 80.5 220 103 79.7 228, 260 10 J 1.07 7.8 3.35 0.05-0.3 79.3 211) 60 11 K 1.32 8.0 0 0.05-0.2 73.9 205 85 12 L 1.32 9.5 1.07 0.05-0.2 75.6 212 150 13 M 1.32 7.5 2.19 0.05-0.3 76.8 215 145 14 N 1.32 7.8 2.26 0.05-0.3 77.1 208 50 '7808959-6 -22 Table X (continued) 77.5 223 116 77.5 222 215 15 0 1.32 7.3 2.49 0.05-0.3 77.5 227 167 16 P 6.55 9.4 0 0.05-0.3 50 215 30 17 Q 6.55 8.5 15 0.05-0.3 74.8 200 90 18 R 6.55 8.7 21 0.05-0.2 77.6 191 30 in: In this case, an amount of 3 was used instead of 1.5 ppm 1,2-dichloro- ethane, the temperature being corrected to 1.5 ppm from 3 ppm.

**) This catalyst was prepared by a single simultaneous impregnation and heated in air at 300.

Tests not performed in accordance with the present invention Serie A Catalysts, which contained varying amounts of lithium, an al- potassium metal which does not fall within the scope of the present invention was prepared using the starting material and the general preparation methodology of Example I. Instead to add cesium hydroxide to the first impregnation solution lithium such as lithium hydroxide was added. They do so prepared catalyst compositions were tested as ethylene oxide catalysts using the apparatus and technology according to Example I. The composition of these catalysts together with results obtained are presented in Table XI below.

Table XI Lithium catalysts prepared with supports with surface areas of 0.19 m2 / g Lithium content Reactor temp. for Oxidation Selection ICT achievement of 52% penalty with respect Silver-million-0? -Gm conversion, ethylene oxide, Cat, content mgev / kg parts' C% flm-o ”7.8 u o“ 251 69.5 NH-1 6.9 28 200 250 73.5 NH-2 6.9 56 390 250 72.4 6.9 72 500 252 72.8 NH-3 *) see footnote *) in Table II.

Series B: Catalysts, which contained varying amounts of sodium, an alk potassium metal which does not fall within the scope of the present invention '7808959-6 23 was prepared using the starting material and the general production method according to Example 1. In the to add cesium hydroxide to the first impregnation sodium hydroxide was added to the ring solution. They thus the prepared catalyst compositions were tested as ethylene oxide catalysts using the apparatus and technology Example I. The composition of these catalysts together with the results obtained are given in Table XII below.

Table XII Sodium catalysts prepared with supports having a surface area of 11.19 rnz / g ßzitrium content Reactor temp. for Oxidation Selectivity Silver V1lite achievement of 52 'with respect to ethylene Cat. halt mgev / kg miljon- OZ-oanvandllng, C oxide, “ß parts NI-O 7.8 Û 0 251 69.5 NI-1 7.1 1.22 28 252 72.3 NI-2 7.1 2.17 50 251 74.1 NI-3 7.1 3.22 74 249 75.7 NI-4 7.1 3.57 82 254 75.5 NI-5 7.1 4.39 101 254 75.5

Claims (2)

7808959-6 s »Patent claim Process for the production of ethylene oxide by direct oxidation of ethylene in vapor phase with molecular oxygen in the presence of a silver catalyst comprising silver and one or more alkali compounds on a porous refractory support, characterized in that the process is carried out using a silver catalyst prepared by a process which involves a) impregnating: a porous, refractory support having a surface area of 0.03-10 m 2 / g with a solution of a compound of an alkali metal having an atomic number of 19-55 in such a concentration that, optionally after extraction with a solvent following either steps b (b) or (c) given below, a content of 0.25-16 mg-equivalent weights of the alkali metal per kg of total catalyst is obtained in the finished catalyst. tor for each m2 of support area per gram of catalyst support (mg / kg) / (mz / g); b) at least partially removing the impregnated support from step a); c) contacting the product from step b) with a liquid phase containing a dissolved silver compound or a slurry of particles of silver or a silver compound in an amount sufficient to deposit 1-25% by weight of silver, based on the total catalyst, on the support surface and d) thermally treating the product from step c) to convert the silver compound to silver metal. Process according to Claim 1, characterized in that the process is carried out at a temperature of 210-285 ° C in the presence of a stationary bed of the silver catalyst.