DD151878A5 - SUPPLY CATALYST OF SILVER - Google Patents

Abstract

The present invention relates to a silver cross-linking catalyst for the production of ethylene oxide and to a process for the preparation of such catalysts and a process for the recovery of ethylene oxide with such catalysts. The object of the invention is to provide an improved process which achieves a synergistic effect on the ethylene oxide selectivity and improves the efficiency of the process. According to the invention, the new silver cross-linker catalyst contains a combination of (a) zesium and (b) at least one other alkali metal selected from the group consisting of lithium, sodium, potassium and rubidium. This combination comprises (a) and (b) in such proportions with respect to the amount of silver therein that is sufficient to increase the efficiency of production of ethylene oxide to a level greater than the efficiencies associated with general working conditions are obtained with the aid of the known catalysts containing either only the relevant amount of (a) or only the relevant amount of (b).

Description

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Supported catalyst made of silver

Field of application of the invention

The present invention relates to silver catalysts "their preparation and their use in the production of ethylene oxide"

Characteristic of the known technical solutions

The preparation of ethylene oxide by the reaction of oxygen or oxygen-containing gases with ethylene in the presence of a silver catalyst is an old and very well developed process. For example, U.S. Patent No. 2,040,782, issued May 12, 1936, describes the production of ethylene oxide by the reaction of Oxygen with Ethylene in the Presence of Silver Catalysts Containing a Class of Metal Activators * In the unaltered Keu edition of US Pat. No. 20,370 issued May 18. 1937 describes Leforte that the formation of olefin oxides causes v / ground ka ¥ m _s by the olefins are caused to combine directly with molecular oxygen in the presence of a silver catalyst. From this point on, the earlier technology has focused its efforts on improving the efficiency of the catalyst in the production of ethylene oxide *.

In the characterization of the present invention, the terms "conversion", "selectivity" and "yield" are used as defined in U.S. Patent No. 3,420,784 of January 7, 1969 at column 3 in lines 24-35 inclusive are «This definition of" selectivity "agrees with that _? as they are in the

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U.S. Patent No. 2,766,261 is described in column 6 at lines 5-22 and in U.S. Patent 3,144,916 at lines 58-61. The definitions of "yield" and "conversion" have different meanings in this field of technology and are not to be used according to the definition, for example in the above-mentioned US Pat. No. 2,766,261 "The Outputs" Efficiency " and "selectivity" as used in the present specification and points of the claim of the invention are considered synonymous.

Since their initial stage of development, the silver catalysts used in the production of ethylene oxide have undergone significant changes. As reported in the art, the silver particles were first applied to support materials with little attention paid to support properties such as effective surface area, pore volume, and chemical inertness. Further developments in this field of technology have resulted in specific technologies relating to the carrier substances or carrier materials containing the silver which have been obtained with greater efficiencies for the conversion of ethylene with oxygen to produce ethylene oxide. Nowadays, most of the vehicles for the silver catalysts are homogeneous, single particulate materials which can be introduced into the interior of a converter with the possibility of the reaction gases and gaseous products of the reaction permeating into and around these particles to move around and be recovered by the converter «. The shape of the carrier is a variable factor, and the particular shape chosen is for the converter used, for the required gas flow and

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characteristic of the effective surface. These are features for optimizing the reaction, taking into account other factors as well *

The inert materials that have been used are typically derived from inorganic materials, generally having a mineral character. In most cases, the preferred carrier is alpha alumina, as described in the patent literature; For example, see US Pat. No. 2,294,383 * 3,172,893 _? 3 332 887, 3 423 328 and 3 563 914 *

The silver applied to these vehicles is typically in the form of small particles. The patent literature shows that the size of the silver is a factor in the effectiveness of the catalyst and, in most cases, the fine particle silver is recovered using standard techniques in the art; See, for example, U.S. Patent Nos. 2,554,459, 2,831,870, 3,423,328, which specify that silver particles having a particle size of 150 to 400 S are used; U.S. Patent 3,702,259 describes a finishing process for the recovery of Silver particles having a diameter smaller than 1 / μm, and US Pat. No. 3,758,418 describe silver particles having a diameter smaller than 1,000 pounds.

The 'application of the silver on the carrier can be achieved by a number of technical _procedures? but the two most commonly used techniques involve in one case impregnating the support with a silver solution followed by heat treatment of the impregnated support for the purpose of depositing the silver on the support material and in the other case

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coating the support with the silver by depositing the silver or by forming the silver in a slurry such that the silver particles are deposited on the support while adhering to the support surface when the support or support material is heated These various processes are described in more detail in various patents, such as in US Pat. Nos. 2,773,844, 3,207,700, 3,501,407 and 3,664,970 (see GB-PS 754 593) and 3 172 893 ·

The effective surface provided by the support has been of considerable interest in the development of silver catalysts. Descriptions of the effective surface area of the catalysts can be found in the following patents: US Pat. No. 2,766,261 (here is described effective surface of 0.002 to 10 m ² / g is suitable); U.S. Pat. No. 3,172,893 (here a porosity of 35 to 65 % and a pore diameter of 80 to 200 are described); U.S. Patent 3,725,307 (which is a τ / effective surface area less than 1 m / g and an average pore diameter of 10 to 15 / μm); US Pat. No. 3,664,970 (here, a carrier having a minimum porosity of about 30 % is used, wherein at least 90 % of the pores have diameters in the range of 1 to 30 / μm and the average of these diameters is in the range of 4 to 10 μm ); and US Pat. No. 3 563 914 (here it concerns a catalyst carrier substance with a

ρ effective surface smaller than 1 m / g, a volume of Of23 ml / g and a particle size between 0.074 and 0.30 mm) *

In the earliest developments of the silver catalysts for the preparation of the prior art, it has been determined that a number of metals, when combined in a combination with

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the silver could act as activators of the silver catalyst. These materials, taken alone, are not catalysts but help to improve the percentage or amount of ethylene oxide recovered. "One of the problems in determining whether these metals appear as activators or not is the nature of the catalysts Reaction itself _β The reaction between the oxygen and the ethylene to form ethylene oxide is a highly exothermic reaction. Highly more exothermic than the reaction, however, is the combustion of ethylene or ethylene oxide to carbon dioxide. These transformations occur simultaneously, and the critical factor in determining the effectiveness of the overall process is the measure of control for these two competing reactions. "Inevitably, a material that enhances the production of ethylene oxide could also be considered as having the full complement Combustion of ethylene to ethylene oxide inhibits carbon dioxide. Thus, there is a problem in the manner of defining whether the material considered to be an activator is indeed an inhibitor of the combustion reaction. It is well known that there are materials which, when added to the reaction, contribute to the formation of a smaller amount of carbon dioxide. Such materials are referred to as inhibitors. There are also materials which, when added to the catalysts, increase contribute a greater amount of ethylene oxide. "Such materials are referred to as activators (promoters). Whether the latter materials are in fact inhibitors or activators seems to be a negligible question. What is significant is the statement that. the result of the reaction is advantageous for the recovery of ethylene oxide. "For this reason, when it comes to determining or characterizing a catalytic process for the production of ethylene oxide

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a significant factor entering into the process or contributing to the qualification of that process, in the selectivity of the process for the production of ethylene oxide ", which means the selectivity as defined above"

The use of alkali metals as activators for the silver catalyst-driven production of ethylene oxide is extremely well known in the art * U.S. Patent No. 2,177,361 issued October 1939 provides an indication of the use of alkali metals in silver catalysts U.S. Patent No. 2,238,471 discloses that the lithium is very useful as an activator, but potassium and cesium are considered undesirable. The examples of that patent use substantially 10% by mass of potassium hydroxide or cesium hydroxide with respect to silver oxide which is used in the manufacture of the catalyst. It is later found in US Pat. No. 2,404,438 that sodium and lithium are effective activators for this reaction. Essentially the same statements can be found in US Pat. No. 2,424,084. US Pat. No. 2,424,086 contains generalizations about alkali metals as activators and specifically specifies the sodium for these purposes. In US Pat. No. 2,671,764, the patentees represented US Pat Conception that the alkali metals in the form of their sulfates act as activators for such silver catalysts. In particular, the patentees found that sodium, potassium, lithium, rubidium or cesium sulfates can be used as activators. PS 2 765 283 describes the pretreatment of a carrier substance with a dilute solution of a chlorine-containing compound and led to the conclusion that such chlorine compounds should be inorganic. Special references to suitable inorganic chlorine compounds included sodium chloride, lithium chloride and

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Potassium Chlorate "This patent specified that the amount of inorganic chlorine-containing compound applied to the catalyst support accounted for 0.0001 to 0.2 mass % based on the mass of the carrier dusting. US Pat. No. 2,615,900 (Sears) describes the use of metal halides in the treatment of the supported catalyst and specifies that such halides may be alkali metals such as lithium, sodium, potassium and cesium. The metal halide is in the range of 0.01 to 50 mass% The patent also specifies that mixtures of the individual metal halides generally classified in the patent can be advantageously used to improve the break-in time of a novel catalyst composition at the same time a moderate but constant effectiveness of the catalyst over an extended period of time during the normal operation riebes is maintained. Thus, a particular metal halide-treated catalyst would develop a short-term high initial activity, whereas other metal halides would provide longer-term moderate catalyst susceptibility. "This patent assumes that the metal halides present in the catalyst in question are used to prevent the combustion of ethylene to carbon dioxide. " Therefore, these materials are classified as passivating agents for the catalyst or as antilcatalysts. US Pat. No. 2,709,173 describes the use of a silver catalyst for the production of ethylene oxide, wherein simultaneously with the introduction of the silver catalyst into the solid support, any alkali metal halides, such as lithium, sodium, potassium, and potassium Rubidiumverbindungen of chlorine, bromine and iodine, provided to increase the total production ναι ethylene oxide «. The patent specifies small amounts of "less than about 0.5 mass SS desirable". In particular, the patent

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Within the range of about 0.0001 to about 0.1 mass%, the patent states that, although the preferred catalyst composition contains a particular activator, this is not always necessary because In preparation of the catalyst, the alkali metal halide can be converted to some extent into the corresponding alkali metal oxide which acts as an activator

2766261 the statements of US Patent No. 2,238,474 appears to beher- "Zigen _s where namely cesium and potassium are considered detrimental and unwanted in silver catalysts; However, US Pat. No. 2,769,016 states that sodium, potassium, and lithium are to be considered as activators when used in silver catalysts. "This latter patent also recommends pretreatment of the carrier substanz with dilute ones Solutions of Sodium Chloride, Lithium Chloride or Potassium Chlorate U.S. Patent 2,799,687 (Gould et al.) States that the addition of the metal halides within the range described by Sears in U.S. Patent 2,615,900 is not productive for optimum results More particularly in the case of the alkali metal halides, especially the chloride and fluoride of the sodium and potassium. The patentees recommend that the inorganic halide component of the catalyst should be within the range of 0.01 to 5 mass%, preferably within the range of 0, 01 to 0.1 wt, based on the mass of the "oxidative catalytic silver component" U.S. Patent 3,144,416 mentions a variety of metals as activators, and one of them is the cesium

No. 3,258,433 indicates that the sodium hydroxide is an effective activator. US Pat. No. 3,563,913 recommends the use of alkali metals, such as lithium compounds, as active substances.

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vatoren. The preferred amount of the activating material is stated to be about 0.03 to 0.5% by weight of metal oxide based on the base of the carrier. US Pat. No. 3,585,217 states that of the alkali metal chlorides it is known Formation of carbon dioxide "and these" chlorides "can be included in the catalyst" US Pat. No. 3,125,538 discloses a silver supported catalyst having a co-deposited alkali metal selected from the group consisting of potassium, rubidium and cesium in a specified gram atom ratio relative to that Silver * The weight of silver is preferably from 2 to 5% by weight of the catalyst. "The patentees characterize this catalyst as being particularly suitable for the reaction of nitrogen H) oxide with propylene. U.S. Patent Nos. 3,962,136 and 4,012,425 the identical catalyst suitable for the production of ethylene oxide. US Pat. No. 3,962,136 describes the simultaneous application of alkali metal all with the silver on the support, v / obei the alkali metals in their final form on the support as oxide present, the oxides consist of cesium, rubidium or mixtures thereof in optional combination with a smaller amount of an oxide of potassium. The proportions of such oxides are from about 4 _s 0 χ 10 -5 mass% / kg to about 8.0 -10 mass% / kg of the total catalyst, but US Pat. No. 4,010,115, issued March 1, 1977, differs thereby in that the oxide of the potassium is used here as an oxide of the alkali metal with optional combination with a smaller proportion of an oxide of rubidium or cesium The patent application with the number Hr * 317 349 of 21 December 1972 as source for the US-PS 3 962 136 and 4 010 115 and others contain some interesting information that deserves to be mentioned.

In Example 2, which contains some comparative experiments, the preparation of a catalyst is described,

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containing 310 ppm proportions of simultaneously added potassium. It has been found in this context that when used as a catalyst for ethylene oxidation, this catalyst is inactive for the production of ethylene oxide. However, we have found that that amount of potassium in the catalyst is within the range of that disclosed in US Pat. PS described 4,010,115, is effective for the production of ethylene oxide, although no details are given in the relevant patent to "see this on · = _β to reaffirm

British Pat. No. 821,439 based on British Patent 1,489,335 discloses that a catalyst can be prepared which is as described in US Pat. Nos. 3,962,136, 4,012,425 and 4,010,115 (Nielsen et al ) in the Belgian patent and the British equivalent, a porous refractory support having a specified effective surface is first impregnated with an alkali metal in order to apply it to the substrate To apply support material in specified amounts (both the proportions and the nature of the porous support are equivalent to those which are explained in the US-PS (Meisen and others) mentioned above). The support material is then dried to bind the alkali metal, and then the silver is added to the support. This method corresponds to sequential deposition of the alkali metal promoter and the silver catalyst, and yet substantially the same type of catalyst was obtained by the simultaneous application of the alkali metal and silver "This could be demonstrated by comparing the data in the examples of the Belgian PS with the data in the above mentioned Nielsen et al. US patent" The critical element in the method of application

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of the alkali metal alloy on the carrier seems doubtful in the light of that kind of description and description in US Pat. Nos. 4,033,903 and 4,125,480, which teach that a silver-containing catalyst used is a convenient addition of one or more elements of potassium It is obvious that such a treatment regenerates the ability of the catalyst to improve the selectivity towards the ethylene oxide. Another patent which refers to a post-addition of alkali metal such as cesium , which gives results equivalent to either a previous addition or a simultaneous addition, is U.S. Patent No. 4,066,575.

US Pat. No. 3,962,136 and related patents have been assigned to U.S. Patent Application to Ifd _e Hr. US Pat. No. 3,962,136 states that "the highest selectivity with potassium-modified catalysts is typically less than that achievable with rubidium" or cesium-modified catalysts under otherwise comparable state conditions "(See US Pat column 2, lines 38 »42). U.S. Patent Application to Ifd, Ur. 216,188, contains a drawing that illustrates the relative effectiveness of rubidium, cesium, and potassium to improve the selectivity of ethylene oxide when these elements are used in a silver catalyst. The graph shows that curve C, which represents the addition of cesium, gives the greatest degree of selectivity enhancement, while curve B, which represents the addition of rubidium, takes an intermediate and is superior to the potassium addition represented by curve A. In a change of 11 April 1975 in the US patent application with the Ifd · Kr ₀ 480 896 of June 19, 1974, which is to be regarded as the source for the application of the US-PS 4,010,115, goes

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Applicant believe that the invention and the points of the invention claim do not include "synergistic effects with the use of the mixtures" of the alkali metals. The same statement can be found in the change of 11 April 1975 in the US patent application with the Lfd * ITr * 471 398 of 20, May 1974 »which is to be regarded as the source for the application of US Pat. No. 4,012.

DE-OS 2 640 540 describes in its examples a silver catalyst for the production of ethylene oxide containing sodium and either rubidium, potassium or cesium. Table 1 of this specification contains the alkali content of all the catalysts obtained in the examples of A note to the table states that the presence of potassium in all the catalysts studied (except one that did not have cesium) was attributed to the impurities in the vehicle. The concentration of such impurities was below that for The description does not state that the cesium can be advantageously combined with the potassium and / or sodium nor does the efficiencies reported in the table illustrate any synergistic interaction of the cesium with the catalyst sodium or with de n Potassium impurities in the catalysts *

The specification of Japanese Patent Application Lfd. 3STR. 95 213/75 relates to a process for the preparation of. Ethylene oxide using a catalyst composition of silver, barium, potassium and cesium in specified atomic ratios. Table 1 of this specification summarizes the efficiencies achieved with the various catalyst compositions of the Examples. No synergism with

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Cesium and potassium were demonstrated by any of the cesium-potassium, barium mixtures of the Examples. "Indeed, a comparison of some of the examples in Table 1 appears to illustrate the absence of cesium-potassium synergism, namely, that with a. Cesium-potassium mixture achieves efficiency lower than the efficiency achieved with the same amount of cesium in the absence of potassium

For example, the two examples 3 and 7 relate to catalysts having an identical atomic ratio between cesium and silver (0.05 atoms / 100 atoms Ag) but with different potassium contents. The atomic ratio of potassium in Example 3 is 0.001 atoms K / 100 Atoms Ag, and the corresponding ratio in Example 7, corresponds to 0.05. The efficiency achieved in Example 3 was 76.4 % _t and that in Example 7 was 75.9 %. Thus, the larger potassium content in Example 7 resulted in a decrease in the efficiency of the catalyst. Similarly, Examples 1 and 4 relate to catalysts having an identical atomic ratio between cesium and silver, the catalyst in Example 1 containing an amount of potassium Magnitude greater than that of the catalyst in Example 4 * Nevertheless, the reported efficiencies for both catalysts are essentially the same, 76.7 % and 76.6% for Examples 1 and 4, respectively *

US Pat. No. 4,039,561 describes a catalyst for the production of ethylene oxide. This catalyst contains silver, tin, _s, antimony, thalium, potassium, cesium, and oxygen in specified atomic ratios. "Cesium-potassium mixtures are not described as desirable combinations." In fact, Table 1 of the patent describes a silver-cesium-potassium combination. in the sense of a

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"Control" example, not in accordance with the invention described, and with a selectivity of 73 * 0 % is achieved * It is a value that is significantly smaller than the selectivities shown in the 45 examples in Moreover, the efficiencies in Tables 2 and 3 for the various catalysts can not be used to demonstrate the existence of any synergetic combination between cesium and potassium among the numerous combinations of elements. It is also noteworthy that the above-mentioned US Pat. No. 4,039,561 claims priority over a Japanese Patent Application of 1973, and following this application, the same applicant claims Japanese Patent Application No. Hei. 25 703/77, in which a catalyst for the production of ethylene oxide from the same metal The elements described in the examples of the latter Japanese patent application are similar to those in the US patent. The influence of cesium and potassium in the catalyst composition as described in the US patent is therefore likely to be insignificant.

The BE-PS 854 904 describes silver catalysts with various mixtures of sodium and cesium. GE patent application GB 2 002 252 A describes in Table 2 carrier silver catalysts with various mixtures of cesium and thallium some of which additionally contain potassium or antimony. US Pat. No. 4,007,135 generally describes (in column 2, lines 25-30) silver catalysts for the production of alkylene oxide containing silver. Together with an accelerating amount of at least one activator selected from the group lithium, potassium , Sodium, rubidium, cesium, copper,

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Gold, magnesium, zinc, cadmium, strontium, calcium, mob, tantalum, molybdenum, tungsten, chromium, vanadium and barium. * European Patent Publication No. 0003,642, in Table 3, describes silver-containing catalysts containing mixtures of potassium and cesium and the catalyst with a sodium and cesium content * The above publications contain no evidence of a synergistic interaction of the cesium with other alkali metals.

The BE-PS 867 045 describes carrier silver catalysts containing an amount of lithium, and a substantially lower Hengenanteil of an alkali metal selected from the group of cesium, rubidium and / or potassium, Table 1 of the patent describes three catalysts, all contain cesium, sodium, potassium and lithium, the lithium concentration being at least an order of magnitude greater than the concentration of cesium or potassium. Referring to Table 1, the catalysts L1, L2 and L3 have appreciably different concentrations of cesium, potassium and sodium but in Table 2 it is shown that these catalysts have substantially similar selectivities. There is no evidence of synergistic Y / echselwirkung cesium either the * ^v alium or by liatrium in the described silver catalysts

The BE-PS 867 185 describes carrier silver catalysts for the production of ethylene oxide with a specified amount of potassium and at least one other alkali metal selected from the group of rubidium and cesium, Table 1 describes the composition of 14 potassium-containing catalysts, of which two potassium in one Combination with cesium contained (catalyst G and H), It is

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it can be seen that the selectivities of catalysts G and H are identical at a pressure of 1.03 bar, but slightly different at the higher pressure of 16.55 bar. From the data, no silver-potassium-cesium synergism can be inferred. ,

Object of the invention

The object of the invention is to provide a catalyst for the production of ethylene oxide which has a synergistic effect as ethylene oxide selectivity and a selectivity greater than that anticipated or described in the prior art.

Explaining the essence of the invention

It is an object of the present invention to use at least two alkali metals (excluding prankum) for silver catalysts used in the production of ethylene oxide, of which one alkali metal corresponds to cesium and each of the alkali metals is to be used in such a proportion. that the combination thereof with respect to the proportion of silver in the catalyst gives a synergistic effect on the ethylene yield.

The catalyst according to the present invention consists of a silver support catalyst. The catalyst contains a combination of (a) cesium and (b) v / at least one other alkali metal selected from the group consisting of lithium, sodium, potassium and rubidium (a) and (b) in such Iviengenanteilen with respect to the amount of silver therein are present _s suffice the order to a 'value to increase the efficiency of the production of ethylene oxide which is higher than the efficiencies _s of the frame. general

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Working conditions can be obtained with the aid of the catalysts in question, which correspond to the catalyst according to the invention, except that one catalyst contains the relevant amount of (a) and the other catalyst the relevant amount of (b), instead of both (a) and (b Thus, during use in the production of ethylene oxide, the catalyst contains a combination of cesium and one or more other alkali metals (excluding francium) in an amount which provides a synergistic effect according to the definition given below For example, the process of the present invention defines such synergism as a puncture of the silver content of the catalyst. Thus, for any given amount of silver in the catalyst, the present invention provides the appropriate correlation between the alkali metal and the silver, thereby permitting specific combinations of cesium and one or more other alkali metals to permit efficiencies the production of ethylene oxide which exceeds the higher efficiency which can be achieved with such an amount of silver when combined with the relevant amount of either cesium or the other alkali metals in such a mixture.

The invention described in more detail below defines the binary alkali metal combinations cesium lithium, cesium = sodium, cesium potassium and cesium rubidium, which, in combination with silver in a particular catalyst support and with a corresponding catalyst preparation contribute to a synergistic result However, catalysts are not limited to binary combinations of the alkali metal. Others. Alkali metals may advantageously comprise any of the aforesaid synergistic binary

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be added to the purpose of increasing or decreasing the work tempera ture of the catalyst, to improve the initial catalyst efficiency during commissioning and / or to outperform the aging properties of the catalyst over longer working hours,. In some cases, the addition of a third or even a fourth alkali metal to an otherwise synergistic binary combination will cause a further increase in the efficiency of the catalyst.

The mathematical relationships from which the synergistic binary alkali metal combinations of the present invention are derived are discussed below and described for illustrative purposes by a cesium-potassium combination. Binary combinations of cesium with any other alkali metals in accordance with the present invention are readily understood an analogous method is determined wherein the particular alkali metal of interest for potassium is substituted in the method described below.

The relationship between cesium, potassium and silver to achieve a synergistic result, as defined herein, is characterized by a mathematical equation or mathematical model, the efficiency being expressed as a puncture of the silver in mass%, cesium in mass% and of potassium in mass% of each other * These elements are deposited on the carrier substance of the catalyst. Thus, a synergism with mixtures of cesium and potassium can be obtained at any concentration of silver in the finished catalyst *

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The general form of the mathematical equation under reference as an "efficiency model" defines the efficiency (or selectivity) as a puncture of the mass $ of silver, cesium, and potassium with deposition of these elements on the catalyst as catalyst:

Efficiency in % sb _Q + b ₁ (BG) + b ₂ (BCs) + b- (BK)

+ b ₄ (BG) ² + b ^ BCs) ² + b _g (BK) ² * b _? (BG χ BGs) + bg (BG χ BK) + b ^ BCs χ BK)

where b ₀ , b ^, bg, b «, b. _s b ^, bg, brj ₉ bg and bq are the respective coefficients for each member of the ion exchange model and are composed of a series of constants specific to a particular catalyst support and a particular method of catalyst preparation in accordance with a designated series of experiments the description below. The value of some of these coefficients can be equal to UuIl.

BG -ss (mass% Ag - mass-jS Aeg);

where mass -% Ag = average value of mass% Ag using in the intended series of experiments.

BGs = (Mass Cs - Mas se- ^ Cs);

where mass-> Cs = average value of mass ~% Cs using in the intended series of experiments «

BK = (mass% K - mass% K);

where mass ^ K = average value of mass% K using in the intended series of experiments «

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The intended series of experiments is most conveniently constructed in the form of a composite structure with three independent variables as described by · «L · Davies in the paper" The Execution and Analysis of Industrial Experiments, "Hafner Publishing Company, 1960, p. 532 . 535, planned. For this purpose, the three independent variables correspond to the mass% of silver, cesium, or potassium. The ranges of each variable are chosen so that the selectivity and activity of all catalysts in the foreseen series of experiments among the It is therefore desirable to first perform some preliminary experiments to find out the particular area in order to determine the appropriate ranges of cesium and potassium for this purpose. Hull% by mass of cesium and / or potassium corresponds to a convenient lower limit for use in the composite setup * The upper concentration limit of cesium and potassium can be readily determined by a series of experiments with catalysts which either successively add larger quantities Cesium or potassium. This is done as follows: A starting catalyst is prepared (using a manufacturing process, if desired, as further described below in the Examples) containing a small amount (of the order of about 0.001% by weight) of either cesium or Potassium with a constant amount of, say, 7% Hasse contains "% silver." The selectivity of this catalyst is then selected to yield ethylene oxide among the desired. Search conditions determined. This experiment is then repeated with a catalyst containing twice the amount (0.002 mass) of the alkali metal allene. Thus, experiments are repeated in a series of experiments, each successive experiment using a catalyst which absorbs the double

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pelten alkali metal content of the catalyst of the previous experiment, until the measured selectivity of the last tested catalyst is smaller than that of the starting catalyst, the upper limit of the cesium or potassium concentration is defined in this way for the composite structure ·

The iterative method described above can be advantageously changed to more quickly determine the upper limit of the concentration in the case where it is observed that a double increase in the alkali metal content of the catalyst does not produce a significant change in the selectivity of the catalyst. In particular, such a peak is very likely to occur, for example, when dealing with lithium or sodium catalysts (depending on the particular carrier and manufacturing process used), as opposed to other alkali metal catalysts in the context of the art general rule the efficiency is more sensitive to an increasing alkali metal concentration. Accordingly, in the event that the efficiency of the catalyst remains substantially unchanged when the alkali metal content of the catalyst has been doubled, use a 10-fold increase in the alkali metal content in the iteration described above until the measured efficiency of the last one Catalyst is smaller than that of the starting catalyst. Following this, it may be desirable to repeat the last iteration step using a lower alkali metal concentration, such as using a 3 or 5 fold increase in the alkali metal content to more accurately determine the upper limit of the alkali metal concentration for the composite construction *

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The range of silver concentration in the composite embodiment may typically be 6 to 16 mass%, with an average value of silver (mass% Ag) of 11 Hasse% to be taken. Similarly, the ranges of cesium and potassium concentrations typically correspond to 0.0 to 0.02 Hasse%. For rubidium, too, the concentration range is typically 0.0-0.02 mass%, while for lithium and sodium, the ranges are characteristically 0.0-0.1 mass%. * For some vehicles, the upper concentration limit may be cesium and / or or potassium may be about 5 to 10 times larger. "In particular, this probably applies to" inert substances containing exchangeable cations, "

Table 11 # 5 on page 533 of the above-mentioned Davies publication describes a three variable composite construction based on the units of -oC, -1, 0, +1 and + C ^, where -1 is a "low level" of represents the variable concerned; +1 expresses a "high level" of such a variable; 0 represents the average value of the variables; -o (denotes a value slightly lower than the value represented by -1, and where + CK denotes a level slightly higher than the value +1, the specific choice of ~ # and + α is not critical. However, Table 11.6 on page 534 of the Davies publication suggests values for -CC and -ΐ-CX that are particularly useful for a composite construction according to the present invention.

The envisaged series of experiments is thus typically composed of 16 to 20 experiments, testing catalysts with different concentrations of silver, cesium and potassium ". Thus, for example, a preferred composite construction results in which

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mass% of silver is 7.0 to 15.0, mass% of cesium is 0.0 to 0.02 and mass% of potassium is 0.0 to 0.01 s as follows:

Mass% Silver Mass- $ Cesium Mass% Potassium

9 0.005 0,002 13 0.005 0,002 9 0,015 0,002 13 0,015 0,002 9 0.005 0,008 13 0.005 0,008 9 0,015 0,008 13 0,015 0,008 11 0,010 0.005 11 0,010 0.005 7 0,010 0.005 15 0,010 0.005 11 0.0 0.005 11 0,020 0.005 11 0,010 0.0 11 0,010 0,010

The catalysts of the foreseen series of experiments are tested by means well known in the art for measuring their selectivity and activity. A convenient measure of the activity, d, for the degree of conversion of the reactant into a product, respectively Time unit, is the temperature required to obtain either a fixed ethylene oxide production or to obtain a selected value of ethylene conversion (or oxygen-off conversion) in H 2 O. Thus, a mathematical equation for the catalyst temperature (temperature «-

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model) in a manner similar to the efficiency model, we obtain two behaviors (selectivity and temperature) for each catalyst that correspond to the three controlled variables (percent of silver, cesium, and potassium ). The relationship between the respective behavior and the controlled variables is obtained by applying these data to equations or mathematical models according to the least squares method as described in Chapter 8 of the book "Statistical Methods in Research and Production" of 0 «. L. Davies and P, L. Goldsmith, Longman Group, Ltd., London, 4th Edition, 1976. In practice, the mathematical models of such data are routinely fit with the aid of a digital computer as described in the book "Applied Regression Analysis" by Ii, R, Draper and H. Smith, John Wiley and Sons, Ine, 1966, p resulting models (the efficiency model and the temperature model) describe the relationship between the behaviors and the controlled variables,

It is well known in the art that the number of experiments required to establish mathematical relationships among many variables depends on the reproducibility of the data. Thus, in a compound setup with approximately 16 experiments, it may occasionally be necessary to to repeat the whole series of the intended experiments or a part of these experiments to determine the relationship between the efficiency and the. Determine the Mass of Silver, Cesium, and Potassium Accurately to Achieve an Acceptable Level of Statistical Confidence "In practice, it has been found that in a given series of about 16 experiments, the silver is varied between about 7 and about 15 "

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a complete repetition of the intended experiments is usually sufficient to establish this relationship, assuming that the standard deviation of a single experimental test result is not greater than about 0.7 % efficiency units. During the course of the experimentation, data which does not correspond to the intended series of experiments can be taken over, which are useful for the development of the model described above. For example, data from both the above-mentioned preliminary experiments for finding the respective regions and any additional experimental data of interest with respect to the particular catalyst carrier and preparation process are desirably taken into account together with those data. which were derived on the basis of the composite structure. The equations are thus adapted to the data. As a result, under practical conditions, data from about 30 to 60 experiments may be available for the development of the Wir, kungsgrad and temperature models.

The general form of the mathematical equation below referred to as the "temperature model" defines the temperature as a function of mass% of silver, cesium, and potassium deposited on the support of the catalase. The notation is as follows:

temperature in a ⁰ C = _Q + a ^ BG) a ₂ -S- (BCs) +

+ a ₄ (BG) ² + a ₅ (BCs) ² +

χ BG) + a ₈ (BG x BK)

χ BK)

where a, a-, a ₂ , a-, a ,, a, -, ag, a ~, a _g and a "'denote the respective coefficients for each term in the temperature model."

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The values of some of these coefficients may be Hull, BG, BCs. The value of some of these coefficients may be Hull, BG, BCs. The value of some of these coefficients may be Hull, BG, BCs and BK correspond to the definitions given above.

The most convenient use of the efficiency and temperature models for defining the range of synergism for any selected mass% of silver in the catalyst is to represent the efficiency and temperature responses in graphical form, generally to understand level line images as described in Chapter 11 of the above-mentioned book "The Execution and Analysis of Industrial Experiments". Thus, Figures 1 and 2 contain the level diagrams and the temperature for a selected vehicle and a catalyst preparation method with 7 and 13 mass% silver, respectively. The level line images were derived from a designated series of experiments in which the hate% on silver 5 »88 to 16.05, the mass% of cesium 0.00 to 0.019 and the mass% of potassium 0.00 to 0.021 corresponded. Table 1 below contains a summary of the experimental data available for the selected catalyst support and catalyst preparation process from which the ITIVA line images were derived. The experiments were performed in two different experimental transducers according to the standard test procedure described below under the heading " catalyst comparisons ". The experiments used two similar but slightly different carriers. Table 1 represents the

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experimental data on a synthetic basis, d, h. the data are adjusted to compensate for the observed differences between the reactors and the catalyst supports used,

Table 1: Experimental data

Mass-SS Ilse ~ $ Dimensions-% Temperature ⁽⁰ O) efficiency silver cesium potassium 256.0 (%) 11.14 0.00477 0.00158 256.4 73.9 10.53 0.00897 0.0 256.0 77.5 11.14 0.00479 0.0 256.0 72.9 11.01 , 0.00941 0.00312 258.0 77.4 11.21 0.00240 0.00080 282.2 70.7 10.92 0.01865 0.0 257.2 74.3 11.04 0.00941 0.0 255.0 76.3 11.04 0.00941 0.0 270.7 76.3 11.09 0.01421 0.00412 263.0 75.7 10.41 0.0 0.0 265.0 68.5 10.41 0.0 0.0 292.6 68.4 11.16 0.01909 0.00633 267.0 72.0 10.94 0.01403 0.0 262.0 76.7 10.70 0.01128 0.00379 293.0 77.5 9.08 0.01900 0.00315 269.9 71.8 9.31 0.00968 0.00645 254.9 76.6 13.17 0.00617 0.00102 260.0 74.2 9.10 0.00323 0.00214 259.1. 72.7 13.14 0.00915 0.00613 259.6 77.5 11.11 0.00950 0.00315 260.3 77.6 Ii, 31 0.01206 O ₅ O 260.4 77.4 11.05 0.00236 0.00078 255.8 70.1 12.72 0.00311 0.00207 263.0 71.6 16.05 0.00941 0.00313 269.1 77.7 α oo \) - OO 0.00924 0.00306 76.8

2 197 62 - 28 - 8 _β 10. 1980 Efficiency (%) cesium It / la s se -% potassium AP B 01 J / 219 762 76.7 0.01421 0.00157 57 155 18 75.4 Mass% silver 0.00462 0.00450 Tempera ture ( ⁰ C) 69.9 11.04 0.0 0.00613 268.9 74.4 10.89 0.00630 0.00105 256.4 77.2 10,80 0.01288 0.0 260.5 73.7 8.93 0.01341 0.0 260.4 77.1 15.51 0.00897 0.00810 266.4 77.8 6.03 0.00888 0.00800 280.3 73.3 13.11 0.0 0.01230 266.2 76.0 16.00 0.01562 0.00469 264.3 77.0 10.93 0.01313 0.00386 263.4 68.2 12.95 0.00150 0.0 277.1 78.3 13.12 0.01047 0.00297 268.1 74.5 12.85 0.01784 0.00540 264.4 77.0 13.12 0.01384 0.00407 257.3 77.2 13.26 0.01384 0.00407 282.3 78.3 12,91 0.01038 0.00295 269.4 78.6 12,91 O _$ O1O38 0.00295 269.8 ^x 67.0 12,91 0.00150 0.02100 257.0 72.2 12,91 0.01038 0.01500 257.2 73.7 13,00 0.00150 0.01470 299.0 72.3 13,00 0.01056 0.01220 290.7 75.2 6.88 0.00594 0.01010 288.6 75.7 7.14 0.00727 0.00192 289.2 76.9 7.06 0.01153 0.00330 280.4 77.6 8.00 0.01171 0.00339 263.3 76.5 8.00 0.00749 0.00199 274.4 69.0 8.15 0.00150 0.0 272.7 75.5 8.30 0.01056 0.0 262.2 76.2 8, Q3 0.01056 O ₅ OO4OO 268.0 7 _s 00 264.0 7.00 271.0

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The specific efficiency and temperature models derived from the above data according to the above-mentioned least squares method can be stated as follows:

Efficiency in % = 77.19. + 0.196 (BG) + 133.4 (BCs)

+ 120.5 (BK) - 63787.0 (BCs) ² "- 47229.0 (BK) ² + 52.1 (BC χ BCe) - .60823.0 (BCs x BK) and

Temperature in ⁰ C = 259.44 - 1279 (BG) + 1555.8 (BCs)

+ 794.1 (BK). + 0.3466 (BG) ² + 168544.0 (BCs) ² + 146856.0 (BK) ² + 132807.0 (BCs χ BK)

v / obei: BG = (mass% Ag - 11.0) BCs = (mass% Cs - 0.01) BK = (mass% K - 0.003)

Figures 1 and 2 show high-efficiency level line images at a constant potassium / cesium concentration space temperature. The darker lines represent selectivity levels with selectivity values for each line. The brighter, discontinuous lines represent temperature level lines with temperatures indicated in ⁰ C * The efficiency and temperature for points between the designated level lines can be interpolated * The maximum selectivity achievable for each combination of cesium and potassium is as a function of the cesium concentration the curve labeled SeI ₁ , reproduced. This curve represents the maximum synergism that can be achieved for any given cesium value. The synergism curve (denoted "A" in Figures 1 and 2) separates the range of

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Synergism as defined herein and the ranges of additive and antagonistic effects. "Additive effects appear when the efficiency obtained with a combination of cesium and potassium corresponds to a weighted average of the efficiencies to be achieved under general conditions with the catalysts in question they are the same as the catalyst containing the said combination, except that instead of containing both potassium and cesium, one catalyst contains the relevant amount of cesium and the other catalyst the amount of potassium in question Efficiency, which is obtained with a mixture of cesium and potassium, less than the efficiencies iDt obtained with appropriate catalysts containing the relevant amount of cesium and the relevant amount of potassium individually as described above. The area between the ordinate, the abscissa and the synergistic curve (curve "A") defines the area of synergism in accordance with the present invention. The right place plains of the synergistic curve "A" represents the range of additive and antagonistic effects according to the present invention above description and thus defines mixtures which are not in accordance with the present invention. The preferred combinations are zvd.sch.en the cesium and potassium those selectivities in accordance with the curve ₁₁ for any given SeI Kiveaulinienbild or near dersel "- ben cause" In general, however, preferred mixtures, those in which cesium and Potassium is present in a weight ratio of about 100: 1 to 1: 100, depending on the particular catalyst carrier and manufacturing process selected. For mixtures of cesium and lithium or cesium and sodium, the preferred mixtures are most often those in which the alkali metals are in a mass ratio from about 1000: 1 to

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1: 1000 are present.

Referring to Figure 1, a catalyst having, for example, 0.003 mass% Cs. and 0 mass% K has an efficiency of about 73 % . The addition of about 0.008 mass% K to this catalyst results in an increase in efficiency to about 76.0 % _t with the maximum selectivity at this cesium concentration (i.e., the value on the SeYy, curve) ). Further additions of potassium to about 0.016 mass% K (ie, the Y on the curve "A") would give efficiencies equal to or greater than those given with the given amount of cesium alone (0.003 mass%). are to be obtained (d _e h »no alkali metal except the cesium is present); Additions of potassium in excess of the 0.016 mass K result in efficiencies lower than those obtainable with 0.003 mass% cesium alone, d. h »we are in the range of either additive effects or antagonistic effects« Nevertheless, such an amount of potassium that produces such antagonistic effects may still provide a catalyst with a rather desirable selectivity and activity for a given mode of operation *

The range of synergism varies with the silver content of the catalyst as described by the efficiency model. Figure 2 illustrates the region of synergism in a silver content of 13 mass% _e ~ SEL. The curve and the synergistic curve (curve "A") of Figure 2 correspond to the previous definition with reference to Figure 1. A comparison of Figures 1 and 2 shows that the efficiency levels are similar, but shifted with respect to the cesium and potassium axes "For example, the efficiency level line for efficiency equal to 76 % in Figure 1 covers an area that

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smaller than the area bounded by the corresponding divisional line in Figure 2. Furthermore, the maximum value of selectivity obtained at 7 % silver is d. the maximum along the SeIj ^ _x MRLs is slightly above 76 % (Figure 1), while the corresponding maximum for 13% by mass silver is slightly above 77.8 % (Figure 2).

The efficiency model and the temperature model that have been developed are specific for a particular method of catalyst preparation, for a particular catalyst support substance, as well as for a particular binary alkali metal combination, either as part of the catalyst preparation or support process, or special binary combinations can change the coefficients of the models and therefore the shape of the level line images derived from them · Thus, the curves "A" and Sei ,. consist of straight lines or curves and intersect one or both axes (namely the cesium axis and that of the other alkali metal in the binary combination) · For example, in Figures 1 and 2, the curves "A" and Se "intersect both axes and the cesium axis an angle greater than 90 °. However, for a different support, a different method of catalyst preparation, or a different binary-alkali combination with cesium, the resulting curves "A" and Sei, - the cesium axis at an angle may be less than 90

Max

cut or parallel to one of the axes. The coefficients for the model and resulting ITi-line maps may be readily determined for each of the above-mentioned changes using the intended set of experiments as described above. "

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The concentration of silver in the final catalyst may vary between 2 hss and 20 mass%, the preferred range being about 6% to about 16 mass% silver.

From an economic point of view, lower silver concentrations are preferable. However, the optimum silver concentration for any particular catalyst will depend on both the economic factors and the performance characteristics of the catalyst, such as the degree of catalyst activity, the rate of catalyst aging, and the reaction temperature.

catalyst Preparation

A variety of methods can be used to prepare catalysts containing combinations of cesium with another alkali metal or with several other alkali metals (other than proline) according to the present invention. The preferred method is composed as follows:

(1) A porous catalyst carrier substance is impregnated with a solution consisting of a solvent or a solubilizing agent, a silver salt in an amount sufficient to deposit the desired silver mass on the carrier, and salts (a) of Cesium and (b) at least one other alkali metal selected from the group consisting of lithium, sodium, potassium and rubidium, in an amount sufficient to cause the respective proportions of (a) and (b) to deposit on the support such that the efficiency of the finished catalyst for producing the ethylene oxide is increased to a level above the levels obtained under general conditions with the respective catalysts being the same as

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said catalyst, other than containing both (a) and (b), one catalyst contains the amount of (a) and the other catalyst the amount of (b) in question; and then (2) the impregnated vehicle is treated such that at least a fraction of the silver salt is converted to silver metal and deposition of silver, (a) and (b), respectively, occurs on the surface of the substrate. · Deposition of the silver and the alkali metal is generally accomplished by heating the support at elevated temperatures for the purpose of vaporizing the fluid within the support and depositing the silver and the alkali metal on the interior and exterior surfaces of the support. Alternatively, a coating of silver and alkali metals may be used on the substrate Carrier substance can be formed from an emulsion or slurry in which the elements to be deposited are, followed by heating of the carrier substance as described above. The impregnation of the carrier substance is generally the

preferred technique for the silver deposition, hereby the silver is used more effectively than in the coating or coating process. The latter are generally unable to cause significant silver deposition on the interior surfaces of the support. In addition, coated catalysts are more sensitive to silver losses due to mechanical wear.

The order of impregnation or deposition with respect to the surfaces of the carrier with silver and alkali metals is optional. Thus, impregnation and deposition of silver and alkali metals can be made simultaneously or sequentially, d "h _e alkali metals before, during or get to silver addition to the Trägersubstanz'zur deposition. The alkali metals

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can be deposited together or sequentially. For example, cesium may be deposited first, followed by the simultaneous or sequential deposition of the silver and other alkali metals (the other alkali metal), or such other alkali metal (s) may be deposited first followed by simultaneous or sequential deposition of silver and cesium.

The impregnation of the catalyst support is carried out using one or more solutions of silver and alkali metal compounds in accordance with well-known simultaneous or sequential deposition methods. In the case of simultaneous deposition, following impregnation, the impregnated support is heated or chemically treated. In the case of sequential deposition, the vehicle is initially impregnated with silver or alkali metal (depending on the order of use) and then heated or chemically treated, as above This is followed by a second impregnation section and a corresponding heating or chemical treatment to obtain the finished catalyst containing silver and alkali metals.

The silver solution used to impregnate the vehicle has a silver salt or a silver compound in a solvent or in a complexing / solubilizing agent, such as in the silver solutions known in the art * The particular silver salt used is not critical and can be made of silver nitrate, silver (I) oxide or

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Silver carboxylates, such as silver acetate, silver oxalate, silver citrate, silver phthalate, silver lactate, silver propionate and silver butyrate, as well as salts of the higher fatty acids.

A wide variety of solvents or complexing / solubilizing agents can be used to solubilize the silver in the impregnation medium to the desired concentration. Among the solvents known and suitable for this purpose in the art are lactic acid (U.S. Patents 2,477,435 (Aries) and 3,501,417 (DeHaio))} ammonia (U.S. Patent 2,463,137) 228 (West and others)); Alcohols such as ethylene glycol (U.S. Patent 2,825,701 (Endler et al.) And 3,563,914 (Wattima)); and amines and aqueous mixtures of amines (U.S. Patent 2,459,896 (Schwarz), 3,563,914 (Wattimena), 3,702,259 (Meisen) and 4,097,114 (Cavitt)).

Suitable alkali metal salts include all those salts which are soluble in the particular solvent or solubilizing agent used. Accordingly, inorganic and organic salts of the alkali metals may be used, such as nitrates, halides, hydroxides, sulfates and carboxylates. When co-deposited together with the silver, the alkali metal salt used is preferably such a salt that does not react with the silver salt in the solution to prevent premature silver precipitation from the salt. For example, alkali metal halides are preferably not used in the lactic acid solution because they interfere with the Reactive silver ions contained therein.

Following impregnation of the catalyst support with silver and alkali metal salts, the impregnated support particles are unabsorbed from any residues

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Solution or slurry removed. This is conveniently effected by removal of the excess impregnation medium, or alternatively by the use of separation techniques such as filtration or centrifugation. The impregnated support is then generally heat treated (e.g., by roasting). to decompose and reduce the silver metal alloy to metallic silver and to achieve deposition of the alkali metal ion. Such roasting may be carried out at a temperature of about 100 ^° C to 900 ^° C, preferably 200 ^° C to 700 ^° C, for a period of time sufficient to convert substantially all of the silver salt to silver metal. In general that the higher the temperature is valid, the kür ~ zer the required reduction period _β example, the reduction may be carried out in about 1 to 5 minutes at a temperature of 400 ⁰ G to 900 ⁰ C * Although an extensive range of time intervals for heating in the art has been proposed to thermally treat the impregnated support (for example, US Pat. No. 3,563,914 proposes heating below 300 seconds, with drying but no roasting being effected around the catalyst U.S. Patent 3,702,259 discloses heating for 2 to 8 hours at a temperature of 100 ^° C to 375 ^° C to reduce the silver salt in the catalyst, and U.S. Patent 3,962,136 provides ¹ / 2 to 8 hours for the same temperature range in proposal), it is only important that the time period for the reduction with the temperature be in such a correlation that substantially a k complete reduction of the silver salt to the metallic silver is considered "Purely for this purpose a continuous or stepwise heating program can be used"

The Y / heat treatment is preferably carried out in air,

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but a nitrogen or carbon dioxide atmosphere can also be used. The technical equipment used for such a heat treatment may make use of a static or flowing atmosphere of such gases to achieve the reduction.

The particle size of silver metal deposited on the support constitutes a punction of the process used to prepare the catalyst. Thus, the particular choice of solvent and / or complexing agent, silver salt, heat treatment conditions and catalyst support to varying degrees may increase the size of the resulting silver particles of affecting. For excipients of general interest for the production of ethylene oxide, a distribution of silver particle sizes in the range of 0.05 to 2.0 μm is typically obtained. However, the role of the particle size of the silver catalyst on the effectiveness of the catalyst in the production of ethylene oxide is not clearly understood. In view of the fact that the silver particles are known to migrate on the surface of the catalyst when used in a catalytic reaction, resulting in significant changes in the size and shape of the silver particles, the silver particle size can not be considered as a significant factor be considered when acting on a catalytic reaction.

Selection of the carrier substance

The catalyst support material utilized in the practice of the present invention may be selected from known porous refractory materials which are resistant to ethylene, ethylene oxide, and other reactants and prodrugs.

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inert under reaction conditions. These materials are generally referred to as "macroporous" and consist of porous materials with effective surface areas less than 10 m / g (square meter per gram of support) and preferably less than 1 m / g _e . E. T ₀ method, as described by Brunauer, S, Emmet, P * and Teller E. in Jo Am, Chem. Soc. ₉ Vol. 60, pp. 309-316 (1938). furthermore characterized by pore volumes in the range of about 0.15 to 0.8 g / g, preferably in the range of about 0.2 to 0.6 cnr / g. The pore volumes can be measured by known mercury porosimetry or by water absorption techniques. Average pore diameters for the above-described carrier substances are in the range of about 0.01 to 100 μm, a preferred range corresponds to about 0.5 to 50 μm.

The support preferably does not contain ions which are exchangeable with the alkali metals introduced into the catalyst, either in the preparation or use of the catalyst, so as not to interfere with the amount of alkali metal resulting in the desired synergism If the carrier contains such ions, they must be removed by standard chemical procedures, such as by dissolution. In addition, if the carrier contains a proportion of alkali metal that is transferable to the silver, thereby interfering with the synergistic combination The carrier may then be treated to remove such excess alkali metal, or the amount of the alkali metal incorporated into the catalyst must be less than the synergistic amount

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the transferred alkali metal brings about the desired synergistic amounts.

The chemical composition of the carrier substance is not exactly critical. The carrier substances may consist, for example, of alpha-alumina, silicon carbide, silicon dioxide, zirconium, magnesia and various clays. In general, materials based on the alpha-alumina are preferred. These alpha alumina-based materials can have a very high purity, i. h * 98% alpha alumina, with the remainder being silicon (IV) oxide, alkali metal oxides (e.g., the sodium hydroxide), and trace amounts of other metal and metal contaminants. Or, the materials may be of low purity; h »about 80% by weight of alpha-Alurniniumoxid, wherein the compensation by a mixture of silicon dioxide, various alkali oxides, alkaline earth oxides, iron oxide and other metal and Hichtmetalloxiden occurs. The lower purity carriers are prepared in such a way as to be inert during the preparation of the catalyst and under reaction conditions. A wide variety of such vehicles are commercially available. The vehicles may be in the form of pellets, extruded rope, balls, rings and the like. The size of the carriers may vary from about ¹ / 16th inch to ^1/2 in. The size of the carrier is chosen to be compatible with the type of converter used. In general, it has been found that when Pestbettumsetzeranwendungen sizes in the range of ^1/8 inch to 3/8 inch are typical in the tube converter most suitable from the use is made under kominerziellen working conditions.

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Production of ethylene oxide

The silver catalysts according to the present invention are particularly useful in the production of ethylene oxide by the vapor phase hydrogen peroxide epoxide of molecular weight * The reaction conditions for carrying out the oxidation reaction are well known and have been extensively described in the prior art processes. This refers to the reaction conditions such as the temperature, pressure, residence time, concentration of reactants, diluents (for example, nitrogen, methane and _C0?), The retarder (e.g., ethylene dichloride) and the like, "In addition, the desirability of recycling unconsumed feedstock to the circulation or use of a continuous flow system, or the use of successive reactions to enhance ethylene turnover through the use of mass transfer devices, is readily ascertained by those skilled in the art are well versed. The particular choice of the way of working is usually determined by the economics of the technical process.

Generally, the process in the Y / executed else that a feedstock, which is composed of ethylene and oxygen, continuously C containing a catalyst converter material at a temperature of about 200 ⁰ C to 300 ⁰ and. a pressure which can vary from 1 atmosphere to about 30 atmospheres depending on the mass velocity and the desired productivity * The residence times in large-scale material converters generally have orders of magnitude of about 1 to 5 seconds. The oxygen may be supplied to the reaction in an oxygen-containing stream, such as

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as an air stream or as a stream of commercial oxygen. The resulting ethylene oxide is separated and recovered from the reaction products using known methods.

catalyst comparisons

The catalysts given in Table II below were all evaluated for comparison under standard test conditions. For this purpose autoclave type "Magnedrive" with backmixing and soil agitation were used, as shown in Figure 2 of the paper by J. M. Berty "Substance converter for catalytic vapor phase studies" in Chemical Engineering Progress, Volume 70, Hr. 5, pages 78 - 84 ». The material converter became 1.0 mol%. Ethylene oxide operated in the exit gas under the following standard entry conditions:

Component Mol ~ #

Oxygen · 6.0

Ethylene 8.0

Ethane 0.50

Carbon dioxide 6.5

Nitrogen for the production of the same

weight of the gases

Ethylene chloride in ppm 7 * 5

The pressure was maintained at 19.3 at (275 psig) is constant and the total discharge amount on 0.640 iir / h (22.6 SGPH, thereby SCPH cubic feet per hour at standard temperature and standard pressure, means namely at 0 ⁰ C and 1 atmosphere) , The concentration of the exiting ethylene oxide was maintained at 1.0 % by reducing the reaction temperature.

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That 's how the people are. Temperature (in ⁰ C) and the catalyst efficiency obtained as the behaviors that describe the performance of the catalysts.

A typical test procedure for testing a catalyst consists of the following steps:

1.80 cm of the catalyst are charged in a backwashed autoclave. The volume of the catalyst is measured in a 25 "4 mm (1") ID measuring cylinder after the cylinder has been knocked out several times to allow the catalyst to fully submerge Measuring cylinder into it · The mass of the catalyst is determined and logged ·

2 * The backmixed autoclave is heated in a nitrogen flow of 0.566 m-fyh (20 SCPH), with the fan operating at 1500 rpm, almost to the reaction temperature. The nitrogen stream is then stopped and the feedstock described above is introduced into the material converter The total exit gas quantity is regulated to 0.640 Er / h (22.6 SCPH). The temperature is adjusted in the next few hours so that the concentration of ethylene oxide in the exiting gas comes to about 1.0 % .

3 * The concentration of the exiting oxide is monitored over the next 4 to 6 days to assure that the catalyst has reached its maximum steady-state performance. The temperature is periodically adjusted to produce an outgoing oxide in an amount of 1 % * The selectivity of the catalyst over the ethylene oxide and the temperature is thus obtained

2 1 Q 7 QO

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The standard deviation of a single test result with logging of the catalyst efficiency according to the method described above is equal to 0.7 % efficiency units.

Tables 2 to 6 below give test results in a summary obtained with silver catalysts without addition of additives and with silver catalysts with cesium in conjunction with an alkali metal or with several alkali metals selected from lithium, sodium, potassium and rubidium , The tests were carried out using a variety of catalyst supports and different manufacturing processes. Catalysts prepared on a similar support by the same production process are identified in the Tables by a common numeral.

Table 2: Results

Experi massed   massed Dimensions-% EPP in % Tenroeratur ment Ag Cs K -H-) in ⁰ C 1A 11.14 0.00379 0.0000 71.7 256 1B 11.14 0.00477 0.00158 73.9 256 ic 10.89 0.00461 0.00450 75.4 256 1D 10.41 0.0000 0.0000 68.4 265 1E 10,80 0.0000 0.00613 69.9 261 1P 10.93 0.0000 0.0123 73.3 264 1G 10,90 0.0000 0.0210 66.6 299 1H 11.04 0.00941 0.0000 75.6 256 11 11.06 0.00941 0.00313 76.9 258 U 10.92 0.0186 0.0000 73.1 283 1K 11.16 .0191 0.00633   72.0 293 1L 8.04 0,004 0,008 76.0 269.3 1M 7.84 - 0.0078 75.0 263.8

19762

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Experi Dimensions-% Dimensions-% Mass-SS EPP in% temperature ment AG os - K ++) in "C 11 8.28 0.0041 - 73.8 258.3 10 8.07 .- 67.3 260.0 1P 14.97 66.7 252.9 1Q 15.19 0.00405 - 72.6 252.0 1R 14,80 - 0.0079 75.5 255.5 1S 15,10 0,004 0.0081 77.9 256.6 2A 17.4 0,000 0.093 73.5 278 2 B 16.6 0.0044 0.088 74.7 279 2C 16.5 0.0085 0,089 74.2 278 2D 17.3 0,000 0,000 68-67 +) 284-299 2E 17.0 0.0044 0.0016 70.8 276 2F 15.7 0.0044 0,069 74.1 280 2G 16.5 0.0092 0.0028 72.2 275 2H 16.5 0.0092 0.088 73.2 287

+) Due to the rapid inactivation of this catalyst, the initial values are given as the final outputs.

-j * +) "EPP" corresponds to the abbreviation for the efficiency according to the previous definition.

Experiments 1B and 1C demonstrate the synergism achieved with silver catalysts containing cesium and potassium mixtures according to the present invention relative to the "cesium only" catalyst IA, which contained substantially the same concentration of silver and cesium , but not potassium. "As used herein, the term" cesium only "refers to a catalyst in which cesium is the only alkali metal which has been deposited on the carrier. * The terms" potassium only "," only " Lithium "and" only with sodium "are defined accordingly for the catalysts in question

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Thus, the efficiency with the combination of the alkali metals in Experiment 1B was about 2 % higher than the efficiency of Experiment 1A achieved with the corresponding "cesium only" catalyst. The further addition of potassium in an amount of 0.00158% by mass (Example 1B) to. to a level of 0.0045 mass% (Experiment 1C), with Ag and Cs kept substantially constant, gave an even greater improvement in the efficiency relative to 1A, which was approximately 3.7 % *. The catalyst according to Experiment 1D did not contain cesium or potassium and gave a relatively low efficiency of 68.4 %. Experiments 1E, 1P and 1G demonstrate that "potassium only" catalysts having substantially the same amount of silver as Catalysts 1B and 1C, which gave selectivity not higher than 73 ° -3 ° , was significantly lower than that achieved with Catalysts 1B and 1C with the mixtures of cesium and potassium. It should also be noted that in addition to a higher efficiency, the catalysts (1B and 1C) according to the present invention at lower temperatures than the catalysts (1Ξ, 1P and IG) "only with potassium", resulting in a h gives higher activity of the catalysts (1B and 1C). Although the "cesium only" (1A) catalyst operated at the same low temperature as the catalysts 1B and 1C, it provided significantly lower efficiency.

The catalyst of Experiment 1H was a "cesium only" catalyst with a cesium content almost twice as high as that of catalysts 1A, 1B and 1C. The addition of 0.0031% by mass of potassium to a catalyst of such composition caused an improvement in efficiency greater than 1 % _t as can be seen in Example 1.

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2 4 Q7CO j ^ / b rf £ -47-

Experiments U and 1K illustrate a non-synergistic combination of cesium and potassium. Thus, the addition of potassium to the "cesium only" U containing etv / a 11 wt.% Silver and a relatively high cesium concentration of 0.0186 wt.% Gave a lower efficiency (1K) catalyst "It can therefore be stated that the combination of potassium and cesium in the experiment 1K did not lead to a synergistic result." However, such a cesium / potassium ion mixture is not in agreement with the present invention. "

Experiments IL through 10 demonstrate the synergism of the present invention for catalysts having a silver content of about 8 mass%. The efficiency of Catalyst 1L with a synergistic combination of cesium and potassium was 1 % higher than that of Catalyst 1M with only potassium and more than 2 % higher than that with Catalyst 11 only. The silver catalyst 10, which does not contain cesium or potassium, achieved an efficiency of almost 9 % below that of the catalyst 1L.

Experiments IP to 1S demonstrate the synergism of the present invention for catalysts with a silver content of almost 15 mass%. The efficiency of Catalyst 1S, which contained a synergistic mixture of cesium and potassium, was more than 5 % higher than the efficiency of the catalyst Catalyst 1Q only with cesium, containing the relevant amount of cesium in such a mixture, and about 2.5 % higher than the efficiency of the catalyst 1R containing only potassium, containing the relevant amount of potassium in such a mixture. The catalyst 1P, which contained no additives, achieved an efficiency of about 11 % below the efficiency of the catalyst 1S ·

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Experiments 2B and 2C demonstrate the efficiencies achieved with potassium / cesium mixtures with a catalyst containing about 17% by weight of silver compared with the catalyst with only potassium of experiment 2A, the addition of 0.0044 Mass% cesium in Experiment 2B resulted in an improved efficiency of 74 »7 % _f compared to the 73» 5% efficiency achieved in Experiment 2A. The silver catalyst 2D, which did not have alkali metal deposition on the support, is shown in the table for comparison purposes.

A comparison of experiments 2E and 2F shows that an increase in the potassium concentration of 0.0016 Hasse-% to 0.069 mass- $ and at a constant cesium concentration, an improvement in the efficiency of over 3 % was achieved. Similarly, comparison of experiments 2G and 2H illustrates that increasing the potassium concentration while keeping the silver and cesium concentrations constant resulted in a 1% improvement in efficiency.

Three catalysts with a silver content of 7% by mass were prepared with the optimum cesium concentration as determined by the efficiency model as described above, obtained from a designated series of experiments. The catalysts (Experiments 3A, 3B, and 3C) all contained about 7% by mass of silver and 0.00906% of cesium without potassium. To demonstrate the mode of action of the efficiency model, three further catalysts were prepared (Experiments 3D »3Ξ and 3E ¹ )» each containing about 7.0% by mass of silver; 0.00606% by mass of cesium and 0.004% by mass of potassium. The difference in the performance of the cesium / potassium catalysts relative to the cesium-only catalysts was predicted based on the efficiency model with about 0.6% efficiency units. Again

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Table 3 below "shows that the actually observed difference in performance is 0.7%, which is to be regarded as a reflection of the agreement with the prediction from the efficiency model." Experiment 3G only provides the efficiency of a catalyst " with potassium "containing the same concentration of silver and potassium in the catalysts of experiments 3-D, 3E and 32?" This demonstrates the synergism achieved with the cesium / potassium combination ",

Table 3: Results

experiment Efficiency in % Temperature in ⁰ C 0.00906 mass% cesium 75.4 263.9 0.00906 mass% cesium 76.0 271.4 265.3 Catalysts only with cesium: 7.0% by weight of silver 75.7 261.4 0.004 Hasse- # potassium 76.1 271.5 75.4 266.1 76.4 270.9 3A Average 75? 5 - 0.17 +) Average 76.2 ~ 0.21 +) 3B Catalysts Cesium plus potassium: 7.0 mass% of silver only with potassium: 7.0 pigs of silver 3C Oj0040% by mass of potassium 72.8 - 3D 3Ξ 3P catalyst 3G.

+) These values correspond to the standard deviations

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Table 4 below illustrates the synergism achieved with a combination of cesium and lithium (Experiment 4G) relative to the corresponding catalyst only with cesium of Experiment 4A and to the corresponding catalyst with lithium only of Experiment 4B. Thus, the catalyst of Experiment 4C had one Efficiency, which was about 10 % higher than that of the catalyst 4B only with lithium and about 3 »5% above that of the catalyst 4A only with cesium *

Experiment 4D demonstrates that when the lithium concentration of the catalyst 4C was increased by about 10 times, the resulting efficiency was reduced by more than 3 % . A comparison of the catalysts 4D and 4E shows, however, that the efficiency achieved with the catalyst 4D was increased by increasing the cesium concentration from 0.0053 mass% to 0.0300 mass%. It should be noted at this point that the catalyst of experiment 4G was inactive only with cesium (corresponding to the cesium concentration of experiment 4Ξ); ie at that cesium concentration no ethylene oxide was recovered. However, the combination of this concentration of cesium with 0.0300 mass% lithium gave a very active catalyst (4E). Similarly, catalyst 4P was found to have a relatively low efficiency of 65.4 % with only lithium (corresponding to the lithium concentration of experiment 4E). Thus, the synergism inherent in catalyst 4E is underlined by the sharp contrast of its efficiency relative to the poor results achieved with catalysts 45 ¹ and 4G.

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Table 4: Results

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Catalysts with cesium and lithium Hassel silver synergistic combinations of lithium Efficiency in % Silver, Experiment 12.8 Mass% cesium 0.0000 72.6 Temperature in © Ο 4A 13.1 0.0052 0.0030 65.9 257 4B 12.8 0,000 0.0030 76.0 267 4C 13.1 0.0052 0.0302 72.8 257 4D 13.0 0.0053 0.0300 78.6 258 4E 13 0.0300 0.0300 65.4 258 4P 13.0 0,000 0,000 inactive +) 268 4G 0.0300 -

+) No measurable ethylene oxide was recovered «

Table 5 below demonstrates the synergism achieved with the catalyst of Experiment 5C relative to the corresponding catalyst of Experiment 5A only with cesium and to the corresponding catalyst of Experiment 5B with only sodium. Thus, catalyst 5C has a 6 % greater efficiency as with the catalyst 5A only with cesium and a 7j2 % greater efficiency than the catalyst 5B only with sodium. Experiment 5D shows that increasing the sodium concentration by 10 times relative to the concentration in the catalyst 5C has the effect of lowering the catalyst efficiency *

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Table 5: Results

Catalysts with synergistic combinations of silver, cesium and sodium

Experimental - mass%. "Hasse" / !? Temperature Silver cesium atrium degrees in % in C

5A 12.8 0.005 0,000 72.6 257 5B 13.0 0,000 0,010 71.4 259 50 13.0 0.005 0,010 78.6 251 5D 12.4 '0.005 0,100 77.6 263

Table 6 below demonstrates the synergism achieved with a silver and cesium catalyst in combination with potassium, sodium and lithium according to Experiment 6A.

The presence of chloride ions in the catalyst concentrations of Experiments 6A, 6B and 6C indicates that at least a portion of the alkali metal salts which were used in the catalyst preparation processes were in the form of the chlorides. The efficiency achieved with the synergistic combination of Experiment 6A was about 1.2 % higher than the efficiency of the corresponding 6C only cesium catalyst and about 9 % higher than the efficiency of the corresponding 6b catalyst with the combination of potassium, sodium and lithium ,

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Table 6: Results

6A 13 , 0 0 , 0132 0 , 001 0 002 6B 13 • 1 0 , 000. 0 , 001 0 002 6C 13 0 , 0132 0 , 000 0 , 000

Catalysts with synergistic combinations of silver, cesium, potassium, sodium and lithium

Ex mass mass "mass mass mass mass WIR Tempepe-%%%%%% Substandard temperature ri- Silver Cesium potassium Na Li CHIO degree ⁰ C ment trium thium chloride in%

0.006 0.0137 78.4 +) 262 0.006 0.0137 69.4 267 0.000 0.0035 77.2 265

+) The values for the efficiency represent the average value of two experiments ·

The catalysts of the invention can be prepared using a variety of excipients and methods of preparation. For example, the defined synergism that can be obtained with combinations of cesium with the other alkali metals is not due to a particular type or chemical composition of the catalyst support, to a particular order of deposition of the silver and the alkali metal, or to a particular class of solvents or solubilizing agents used in the manufacturing process.

The invention is explained in more detail below with reference to some examples. The examples below are detailed procedures for illustrating the methods and the carriers which can be used to prepare the catalysts according to the invention. These examples are given by way of illustration only and

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must not be construed to limit the scope of the invention described herein.

example 1

A catalyst containing 11.14% Hasse, 0.00477 mass% cesium and 0.00158 mass% potassium was prepared as described below on a carrier "A ¹ " of alpha alumina having the following chemical composition and the following physical properties:

Chemical composition of the carrier "A":

alpha alumina 98.5% by mass

Silica 0.74 Hasse ~%

Calcium oxide 0.22 mass SS

Hatrium monoxide 0.16 Hasse%

Iron (III) oxide 0.14 mass%

Potassium in oxide 0.04 mass%

Magnesium oxide 0.03 mass%

Physical properties of the carrier "A":

¥ / effective surface (1) 0.3 m ² / g

Pore volume (2) ο

(or water absorption) 0.50 cm / g

Packing density (3) 0.70 g / ml

Mean pore diameter (4) 21 / Um

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Distribution of pore size and total pore volume in % (4): pore size in, to total pore volume in %

0.1 to 1.0 '1.5

2.0 to 10.0 38.5

10.0 to 30.0 20.0

30 to 100 32.0

100 8.0

(1) The measuring method is described in the book "Adsorption, Effective Surface and Porosity" by S.J. Gregg and K, S. W · Sing, Academic Press (1967), pages 316-321.

(2) The measuring method is described in ASTM standard C 20-46.

(3) The calculated value is based on the known measurement of the mass of the carrier in a graduated cylinder of known volume ».

(4) The measuring method is described in the article "appli ~ extension of the mercury intrusion in the analysis of materials" C "Orr, Jr., Pov / O-'echnology, Volume 3 _t pages 117-123 (1970).

Carrier "A" was impregnated under vacuum conditions as described below with a solution of silver salts and alkali metals. The impregnating solution was prepared in such a concentration that the finished catalyst contained the desired proportions of silver, cesium and potassium. The required concentration of silver, cesium and potassium in the solution for the

given carrier substance is calculated from the packing density (g / cm) and the pore volume of the carrier, which are either known or can be readily determined. * Assuming that the total silver in

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of the impregnating solution, which was in the 'pores' of the carrier, is deposited on the carrier, about 21 Hasse% silver in the solution is necessary to produce a catalyst of about 11 mass% silver on the catalyst. »The required concentration of the alkali metal in solution is obtained by dividing the silver concentration in the solution by the ratio of silver to cesium or to the potassium desired in the final catalyst. Thus, by 11.0 mass% of silver and 0.0047% by mass of cesium, the ratio approximately equal to 2330, and the required cesium concentration in the solution equal to 0.009% by mass. In the same manner, the concentration of potassium in the solution was calculated to be 0.003 mass%. The solution with the desired concentrations of silver and alkali metals was prepared according to the description given below.

Production of the impregnating solution

80.16 mg of ethylenediamine (of high purity) was mixed with 176 g of distilled water. 60.06 g of anhydrous oxalic acid (reagent grade) was then added slowly to the solution at ambient temperature (23 ° C) was being constantly stirred · During this addition, the oxalic acid the solution temperature rose to about 40 ⁰ C, which by the exothermic reaction was conditional. 147 »25 g of silver (I) oxide powder was then added to the diamine-oxalic acid-water solution. Finally, 293 $ 0 g of monoethanolamine, 13 »26 g aqueous cesium solution as hydroxide (0.00444 g Cs / ml solution or 0.0589 g Cs), 34.28 g aqueous potassium solution as carbonate (0.0005669 g K / ml solution or 0.0194 g K) and 120.6 g of distilled water to complete the solution. The solution was filtered and 0.9 g of undissolved silver recovered. The specific gravity of the

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giving about 1,328 g / ml «

Preparation of the catalyst

125 g of vehicle "A" were impregnated in a 12-inch, 50-mm (2-inch) ID glass graduated cylinder fitted with a side arm and suitable stopcocks for impregnating the vehicle under vacuum conditions ~ ml ~ separating funnel containing the impregnating solution was placed through a guiamist plug in the upper part of the impregnating vessel. The impregnation vessel with the vehicle was evacuated to approximately 50.8 mm (2 inches) of mercury pressure for about 20 minutes, after which the impregnation solution was slowly added to the vehicle by opening the stopcock between the separatory funnel and the impregnation vessel until the vehicle was completely free of the carrier Solution covered. "The pressure inside the vessel was maintained at approximately 50.8 mm (2 inches) of mercury." Following the addition of the solution, the vessel was opened to the atmosphere to obtain atmospheric pressure. " The vehicle then remained in the impregnation solution at ambient conditions for about 1 hour. Thereafter, the excess solution was removed for about 30 minutes. The impregnated vehicle was then heat treated as follows to effect reduction of the silver salt and deposition of the cesium and potassium ions on the catalyst surface. The impregnated support was then spread in a single layer on an endless stainless steel (spiral-wound) belt 66.7 mm (2 to 5/8 inches) wide and passed through a square-dimensioned heating zone (50.8 mm χ) 2.5 minutes-long transported 50.8 mm (2 inches χ 2 inches), wherein the heating zone vmrde maintained at 500 ⁰ O by hot air from the bottom upward through the belt and over the catalyst with a Strömungsgeschwindig-

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speed of 7.528 m ^ / h (2β6 SCJ ¹ H) was swept passed · The hot air was generated in such a manner as to pass through a tube of stainless steel having a length of 152.4 cm (5 ft) and an inner diameter of 50, 8 mm (2 inches) heated externally by an electric furnace (tube furnace having an inside diameter of 63.5 mm (2 to 1/2 inches) and a heating zone of 91.44 cm (3 ft) in length). , This electric furnace was capable of delivering 5400 Y /. The heated air in the tube was made from an opening 50.8 mm χ 50.8 mm (2 inches χ 2 inches) just below the moving belt, Upon completion of roasting in the heating zone, the finished catalyst was weighed and calculated on the basis of the mass of the carrier and the known ratios of silver to cesium and potassium in the impregnating solution the catalyst contained 11.14% by weight of silver, 0.00477% by mass of cesium and 0.00158 % by volume of potassium. By chemical analysis, as described below, it was determined that this catalyst had 10.88 mass% of silver in close agreement with the calculated value.

Analysis of the silver was carried out according to the following procedure: Approximately 50 g of the catalyst was ground into powder in a mill and 10 g of it were weighed to the nearest 0.1 mg. The silver (and cesium etc.) in the catalyst sample is dissolved in a warm (80 ⁰ C) 50 / ÄLGEN (vol%) nitric acid solution. The insoluble particles of alminoside were filtered and rinsed with distilled water to remove any adhering nitrate salts of silver, cesium, and the like. This solution was made up to 250 ml using distilled water in a volumetric flask. An aliquot of 25 ml of this solution was prepared according to standard procedures using a 0.1 H solution of ammonium thiocyanate

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and tritrates ferric nitrate as an indicator. The amount of silver determined to be that amount in 250 ml of solution then served to calculate the% of silver in the catalyst sample.

The silver and alkali metal concentrations for all of the catalysts described herein are calculated values as described above.

A catalyst was prepared with 16.6 mass% silver, 0.0044 mass% cesium and 0.088 mass% potassium as described below on a vehicle "B" having the following characteristics:

Chemical composition of the carrier "B":

alpha-aluminum 86.0% by mass

Silica 11.8 mass-jS

Calcium oxide 0.24 mass

Sodium monoxide 0.69 mass%

Iron (III) oxide 0.30 mass- $

Potassium monoxide. 0.54 mass% '

Titanium »(IY) oxide 0.34 mass- $

Physical properties of the carrier "B":

Effective surface (1) 0.10 a / g

Pore volume (2) ~

(or water absorption) 0.40 crcr / g

Packing density 0.72 g / ml

Mean pore diameter (4) 22 / μm

pore size to in, around 0.1 to 1 , 0 1.0 to 10 10.0 to 30 30 100 > 100

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Distribution of pore size (4):

Total pore volume in %

0,0 12 55 33

0.0

(1) The measuring method is described in the book "Adsorption, Effective Surface and Porosity" by S. J. Gregg and K. S * W. Sing, Academic Press (1967), pp. 316-321.

(2) The measuring method is described in ASTM standard C 20-46.

(3) The calculated value is based on the known measurement of carrier hate in a graduated cylinder of known volume.

(4) The measuring method is described in the article "Application of mercury penetration in the context of the analysis of materials" by C. Orr, Jr., Powder Technology, Vol. 3, pages 117-123 (1970).

The manufacturing method continued as follows: a) 333.5 g lactic acid (88% in water) were heated to about 75 ⁰ C, and 1.44 g of ^K 2 ^CC> 3 ^vai ^ 4 ^»8 ^ β aqueous CsOH- Solution (containing Cs of 0.008 g / ml or 0.039 g) was added to the warmed-MiIchsäure, wherein the solution was stirred.

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b) 163.75 g AgpO were added to the heated lactic acid in small portions with stirring, so that the heat generated by the exothermic reaction of Ag "O with the lactic acid did not exceed about 85 ^° C. Most Ag ₂ O and / or silver remained suspended in the solution. This suspension was dark brownish gray in color.

Hydrogen peroxide (3j3 ml) was added in small portions to the above AgPO-lactic acid solution, stirring rapidly to achieve complete dissolution of the suspended substances. A clear yellow solution was obtained »with the temperature of the solution being about 80 ^° C. * (small amounts of lactic acid or water were added to compensate for any evaporation losses). This solution contained about 30.4 % silver, 0.12 % potassium and 0.0078 % cesium.

d) 189 g of the carrier "B" were evacuated and impregnated with the solution obtained in c), the temperature of the solution corresponding to about 80 ° C. The impregnation method for impregnating the Trägerbstbstanz was similar to that described in Example 1 with an additional measure, namely, that the serving for impregnation round vessel with the carrier was surrounded by a heating mantle, which kept the temperature of the carrier during impregnation at about 80 ⁰ C to to ensure that the silver lactate remained in solution.

e) The impregnated carrier according to d) was heat-treated at 400 ^° C. for 4 minutes using the apparatus and general method described in Example 1.

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Example 3

A catalyst containing 13.4% by mass of silver, 0.0091% by mass of cesium, and 0.0027% by mass of potassium was supported on the carrier by the following procedure; "A" (as described in Example 1)

Applying the impregnating solution

78.6 g of triethylenetetramine (of high purity) were mixed with 80 g of distilled water. 51 g of oxalic acid dihydrate (reagent grade) were then slowly added to the continuously stirred amine solution. During this addition, the temperature of the solution rose to 60 due to the exothermic reaction ⁰ C of, 5 »83 g aqueous cesium hydroxide solution (0.009728 g Cs / g solution) and 4.46 g aqueous potassium carbonate solution (0.00369 g K / g solution) were then added to the solution, followed by the addition of 89, 26 g of silver (I) oxide. Finally, 15-28 g of monoethanolaxin was added to the solution along with additional distilled water to make the total volume of the solution 250 ml. The solution was filtered and about 5 g of undissolved silver were recovered.

Preparation of the catalyst

15 g of the carrier substance "A" were evacuated at room temperature and treated with the impregnating solution described above according to the procedure in Example. 1 impregnated. Subsequent to the impregnation, a heat treatment of the support was carried out at 500 ^° C. for 2.5 minutes using the apparatus and general method described in Example 1. · The composition of the finished catalyst calculated on the basis of the mass increase of the carrier corresponded

2 19 7 6 2

the above information.

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Example 4

A catalyst containing 13.04% by mass of silver, 0.0089% by mass of cesium and 0.0026% by mass of potassium was prepared by the following procedure on the carrier "A" (as described in Example 1).

Apply the impregnation solution

114J25 g of aminoethylethanolamine (of high purity) were mixed with 80 g of distilled water. 50.42 g of oxalic acid dihydrate (reagent grade) were then added slowly to the continuously stirred amine solution, the temperature of the solution due to the exothermic reaction to about 60 C increase * 5 * 84 g aqueous cesium hydroxide solution (0.009723 g Cs / g solution) and 4.52 g of aqueous potassium carbonate solution (0.00369 S K / g solution) was then added to the solution, followed by the addition of 89 g of silver (I) oxide. Subsequently, additional distilled water was added to the solution to obtain a total volume of 250 ml.

Production of the catalyzer sector

150 g of the carrier "A" were evacuated and impregnated with the solution described above according to the method in Example 1. Subsequently, the heat treatment of the impregnated carrier substance was carried out at 500 ^° C. for 2.5 minutes using the apparatus described in Example 1 and the general method,

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Example 5

A catalyst of nominally the same composition as in the catalyst of Example 1 (especially 11.1 mass% silver, 0.0048 mass% cesium, and 0.0016 mass% potassium) was prepared as described in Example 1, With the exception that the preparation of the impregnating solution was carried out using aqueous solutions of cesium chloride and potassium chloride instead of cesium hydroxide or potassium hydroxide. After addition of such chloride salts to the silver impregnating solution, the solution remained clear, ie · No precipitation of silver chloride was observed ·

Example 6

A catalyst of nominally the same composition as in the catalyst of Example 1, except that the potassium was replaced by lithium (more specifically, 11.0% by mass of silver, 0.0047% by mass of cesium and 0.003% by weight) Hasse% lithium) was prepared as described in Example 1. The concentration of the solution of lithium was calculated to be 0.00573 mass%. The method of preparation in Example 1 was followed except that instead of adding the potassium carbonate solution to the impregnating solution, 34 g of an aqueous lithium solution as carbonate (0.001094 g lithium / ml or 0.0372 g of lithium) were added.

Example 7

A catalyst of nominally the same composition as the catalyst of Example 1 except that the potassium was replaced by sodium (more preferably 11.0% by mass of silver, 0.0047% by mass of cesium and .alpha

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0.01 Hasse% sodium) was prepared according to the procedure in Example 1. The concentration of the solution of sodium was calculated to be 0.0191 mass. The procedure of Example 1 was followed except that instead of adding the potassium carbonate 34 g of an aqueous sodium carbonate solution (0.00365 g sodium / ml or 0.12515 g sodium) were added to the impregnating solution,

Example 8

A catalyst with 12.59 Hasse-SS silver, 0.0088 mass% cesium, and 0.0025 hasse-potassium was; on a carrier substance "A" (as described in Example 1) by a successive impregnation process, whereby potassium and cesium were deposited on the carrier prior to deposition of the silver as follows: 146 »1 g of vehicle" A were impregnated with 250 ml of an aqueous solution containing 0.05696 g of cesium as the hydroxide and 0.1674 g of potassium carbonate, while maintaining the general impregnation method described in Example 1. The impregnated carrier was then erhandelt at 400 ⁰ C for 2.5 minutes according to the procedure in Example 1 wärmeb., To bring the Zäsium- and potassium ions on the surface of the carrier substance for depositing * Following this heat treatment, the carrier substance has been silver-containing impregnating solution as described below impregnated.

Preparation of the silver-containing impregnation solution

48.9 g of ethylenediamine (of high purity) was mixed with 80 cc of distilled water. 50.6 g of oxalic acid dihydrate (analytically pure) were then slowly added to the solution within 1 hour while stirring was carried out continuously. During this addition of the oxalic acid, the temperature rose.

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Tear of the solution to about 40 ⁰ C due to the exothermic reaction of. 89.34 g of silver (I) oxide powder was then added to the diamine-qalicic acid-water solution. Finally, 17.84 g of monoethanolamine were added to the solution along with additional distilled water to arrive at a total volume of the solution of 250 ml.

Production of the catalytic converter

The above-mentioned carrier "A" was impregnated with the above-described impregnating solution and then heat-treated at 400 ^° C. for 2.5 minutes according to the method described in Example 1.

Example 9

A catalyst containing 13.09% by mass of silver, 0.0089% by mass of cesium and 0.0026% by mass of potassium was prepared on a support "A" (as described in Example 1) by a sequential impregnation method the silver was applied to the support before depositing the potassium and cesium as follows:

Preparation of the silver-containing impregnation solution

48.43 g of ethylenediamine (of high purity) were mixed with 100 g of distilled water. 50.75 g of oxalic acid dihydrate (reagent grade) were then added slowly to the solution at ambient temperature, stirring continuously. The temperature of the solution increased due to the exothermic reaction to about 60 ⁰ C. 88.97 g of silver (I) oxide powder was then added to the diamine-oxalic acid-water solution. Finally, 17.7 g of honethanolamine and 44.0 g of distilled water were added to add the solution

197 62 _ ₆₇ _

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AP B 01 J / 219 762

57 155 18

The specific gravity of the solution was 1.3957 ·

Production of the jatatysator

150 g of the carrier "A" were impregnated with the solution described above and then at 500 ⁰ C for 2.5 minutes according to the method described in Example 1 v / ärmebe acts. Following this heat treatment, the vehicle was impregnated with the impregnating solution, as further described below.

Prepare the impregnating solution with the caustic and potassium

5.791 g of aqueous cesium hydroxide solution (0.009723 g Cs / g solution) and 4.415 g of aqueous potassium carbonate solution (0.00369 g K / g solution) were placed in a 250 ml 4-liter flask and then n-butanol added to the contents of the To bring the volumetric flask to the 250 ml Marlce. The flask was heated to 40 ⁰ C, capped and vigorously shaken until a clear solution was obtained ·

Preparation of the catalyst

The silver-containing carrier "A" described above was impregnated under vacuum conditions with the impregnating solution containing the cesium and the potassium for 15 minutes, and then the excess solution was removed using the method described in Example 1. The heat treatment derTrägersubstanz was then carried out for 2.5 minutes according to the method described in Example 1 at 500 ⁰ C

Claims (21)

8β10. 1980 AP B 01 J / 219 762 57 155 18 A supported catalyst of silver for the production of ethylene oxide, which consists of a combination of (a) cesium and (b) at least one other alkali metal selected from the group consisting of lithium, sodium, potassium and rubidium, characterized in that the combination of (a) and (b) amounts corresponding to the amount of silver contained therein and which is sufficient to increase the effectiveness of ethylene oxide production to a value which is greater than the effectiveness achieved under general conditions with corresponding catalysts, which are the same as the above-mentioned catalysts, except that they do not contain both (a) and (b) but contain one of them, either the corresponding amount of (a) or the corresponding amount of (b). ., (2) the treatment of the impregnated support in that at least a fraction of the silver salt is converted to silver metal and the deposition of silver is effected and of (a) or (b) on the surface of the support. 2 1 97 62 - 70-, only the corresponding amount of (a) or only the corresponding amount of (b), and 2 1 9 7 6 2 - 69 - 2. Catalyst according to item 1, characterized in that silver is present at about 2 to 20 percent by weight. 2 197 62 -68- invention claim 3. Catalyst according to item 2, characterized in that silver is present at about 6 to 15 percent by weight. 4. Catalyst according to item 1, characterized in that the alkali metal is sodium. 5. Catalyst according to item 1, characterized in that the alkali metal is lithium,. 6. Catalyst according to item 1, characterized in that the alkali metal is potassium. 7. Catalyst according to item 1, characterized in that the alkali metal is rubidium. AP B 01 J / 219 762 57 155 18 8. The catalyst according to item 6, characterized in that cesium and potassium are present in a weight ratio of about 100 to 1 to 1 to 100. 9. Catalyst according to item 1, characterized in that the supported catalyst includes alpha-aluminum. 10. Catalyst according to item 1, characterized in that the upper
is. the surface of the supported catalyst is less than 1 m / g 11. The catalyst according to item 1, characterized in that the pore volume of the iTrägerkatalysators is in the range of 0.2 to 0.6 cm / g. 12. A process for the preparation of a supported catalyst of silver for the production of ethylene oxide by means of the vapor phase oxidation of ethylene with a acidic G-as, characterized by (Ο impregnating a supported porous catalyst with a solvent or solubilizing agent-containing solution, with silver salt sufficient to deposit the desired amount of silver on the support, and salts of (a) cesium and (b) at least one other alkali metal which is selected from the group consisting of lithium, sodium, potassium and eubidium ₅ and is sufficient to deposit the appropriate amounts of (a) and (b) on the carrier, so that the effectiveness of ethylene production by means of the finished catalyst on a Value greater than that obtained under normal conditions with the corresponding catalysts, which are the same as those mentioned above, except that they are not both (a) and (b) together but AP B 01 J / 219 762 57155 18 13. The method according to item 12, characterized in that the solvent or solubilizing agent is lactic acid. 14. The method according to item 12, characterized in that the solvent or solubilizing agent is an amine or an aqueous mixture of amines. 15. A method according to item 12, characterized in that the impregnated carrier is heated at a temperature of about 200 ° C to 700 ° C. 16. The method according to item 12, characterized in that the alkali metal is sodium. 17. The method according to item 12, characterized in that the alkali metal is lithium. 18. The method according to item 12, characterized in that the alkali metal is potassium. 19. The method according to item 18, characterized in that in the solution cesium and potassium salts are present in a concentration which is sufficient to Zsäium or AP B 01 J / 219 762 57 155 18 - 71 - 20. Method according to item 12, characterized in that the amount of silver salt in the solution is sufficient to deposit about 2 to 20% by weight of silver on the support. 21 ". The method of item 12, characterized in that the amount of silver salt in the solution is sufficient to deposit about 6 to 16 percent by weight of silver on the support. For this - ^ Rarely drawings