Method for ethylene epoxydation

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for vapor-phase oxidation of ethylene to ethylene oxide. Method involves interaction of ethylene and oxygen in the presence of silver-base highly selective catalyst. On the onset stage of process fresh catalyst is used and on the additional stage of process when cumulative productivity enhances 0.01 kT of ethylene oxide per m³ of catalyst by ethylene oxide the concentration of ethylene is increased in the reaction mixture. Also, invention relates to a method for using ethylene oxide for preparing 1,2-ethanediol or corresponding 1,2-ethanediol ether involving conversion of ethylene oxide to 1,2-ethanediol or 1,2-ethanediol ether wherein ethylene oxide has been prepared by this method for producing ethylene oxide.

EFFECT: enhanced selectivity, enhanced activity of catalyst.

12 cl, 4 dwg, 1 tbl

The scope of the invention

The present invention relates to a method of performing a vapor-phase epoxidation of ethylene in the presence of supported on a carrier of highly selective catalysts based on silver.

Rationale inventions

When the catalytic epoxydecane ethylene modern supported on a carrier catalysts based on silver are highly selective with respect to the receipt of ethylene oxide. In certain operating conditions of their selectivity for ethylene oxide, expressed as the percentage of converted ethylene, can reach values above the limit in 6/7 or 85.7% of mol., previously, based on the reaction equation 7 C₂H₄+6O₂→6C₂H₄O+2CO₂+2H₂O, see Kirk-Othmer'sEncyclopedia of Chemical Technology, 3rd ed., vol. 9 (19080), p. 445, was regarded as theoretical maximum selectivity of this reaction. Such highly selective catalysts that can be included as active components, silver, rhenium, at least one additional metal and, optionally, rhenium copromoter described in EP-B-266015 and in several subsequent patent publications.

Like all catalysts are highly selective catalysts for epoxidation of ethylene on silver-base subject associated with aging deterioration characteristics during normal work and require periodic replacement. Aging is manifested in the reduction of the characteristics of both the selectivity and the activity of the catalyst. The selectivity and activity are the primary (though not the only) determinant of the efficiency of the process. There is therefore a significant economic incentive to delay the need for replacement of the catalyst, keeping these values as long as possible. There are several patent publications, which are aimed at stabilizing the catalyst for the introduction of modifications in the composition of the catalyst or of the material of the carrier, but still did not pay attention on the reaction conditions and in particular on the composition of the supply of raw materials.

It is known for example from EP-A-567273 that, when using the fresh catalyst, working at higher concentrations of ethylene and/or oxygen in the incoming gas into the reactor can lead to a better activity and better selectivity of the reaction of epoxidation of ethylene.

Now it was unexpectedly found that the aged catalysts for the oxidation of ethylene respond differently composition of the gas mixture of reagents than do fresh catalysts oxidation of ethylene, and that in this respect also highly selective catalysts differ from traditional catalysts. More specifically, if fresh, highly selective catalysts the use of higher concentrations of ethylene it turns out is no significant effect on the reaction selectivity for ethylene oxide, for aged highly selective catalysts selectivity is significantly improved. The difference in the characteristic activity of fresh and aged highly active catalysts under the same conditions increased concentration of ethylene has the same orientation. It was found that, in contrast to the highly selective catalysts, aged and fresh traditional catalysts for the oxidation of ethylene do not show such differences in their reactions to the composition of the initial gas mixture.

Brief description of the invention

The present invention therefore proposes a method of vapor-phase oxidation of ethylene to ethylene oxide, which method comprises the reaction of a reaction mixture comprising ethylene and oxygen in the presence of supported on a carrier of highly selective catalysts based on silver, by

- implementation of the initial phase of the operation, which uses fresh catalyst, and

- implementation of additional phases of the operation, when the cumulative productivity ethylene oxide exceeds 0,01 CT ethylene oxide on m³catalyst, where the specified additional phase of the operation increase the concentration of ethylene in the reaction mixture.

In the preferred implementation of the invention provides a method of vapor-phase oxidation of ethylene to ethylene oxide in the presence of supported on a carrier, visocosity the aqueous catalyst based on silver in the performance of win the range from 32 to 320 kg produced ethylene oxide on m³of catalyst per hour, the reaction mixture containing ethylene, oxygen, and optionally carbon dioxide, the moderator ("control response") of the gas phase and the balance inert gases, the reaction temperature from 180 to 325°With, the inlet pressure in the reactor of from 1000 to 3500 kPa and average hourly space velocity of gas (GHSV) of from 1500 to 10000, where the method includes

work on the initial phases of operation where the use of fresh catalyst, the reaction gas mixture containing the ethylene concentration, which is economically optimized balance between performance characteristics of the catalyst (expressed at a given performance w selectivity S in mol.% and an operating temperature T in °C), on the one hand, and losses of ethylene with Stripping, on the other hand, the oxygen concentration, which is consistent with security-related restrictions on Flammability, and

work on additional phases of operation when the catalyst has reached aging, defined by cumulative production of ethylene oxide in excess of 0.5 kt ethylene oxide on m³catalyst, especially a 1.5 CT ethylene oxide on m³catalyst, where specified in an additional phase of the operation the composition of the reaction mixture changed to contain ethylene in Konz is Tracii from 1.1 to 4 times more than the concentration of ethylene used in the initial phase of the operation, and the corresponding optimized and safe concentration of oxygen.

In a further preferred implementation of the invention provides a method of vapor-phase oxidation of ethylene to ethylene oxide in the presence of supported on a carrier of highly selective catalysts based on silver in the performance of w in the range from 32 to 320 kg produced ethylene oxide on m³of catalyst per hour, where the reaction mixture contains ethylene, oxygen, and optionally carbon dioxide, the moderator of the gas phase and the balance inert gases at the reaction temperature from 180 to 325°With, the inlet pressure in the reactor of from 1000 to 3500 kPa and a GHSV of 1500 to 10000, and the method includes

work on the initial phases of operation where the use of fresh catalyst, the reaction gas mixture containing the ethylene concentration, which is economically optimized balance between performance characteristics of the catalyst (expressed at a given performance W selectivity S in mol.% and an operating temperature T in °C), on the one hand, and losses of ethylene with Stripping, on the other hand, the oxygen concentration, which is consistent with security-related restrictions on Flammability, and

work on additional phases of operation when the catalyst has reached aging, sufficient to cause a decrease in the selectivity S of at least 2.5 mol%. and/or increased activity parameter of at least 15°where the selectivity S and the activity parameter of T is such, as will be defined hereafter, and where specified additional phases of operation change the composition of the reaction mixture so that the mixture contained ethylene in a concentration of from 1.1 to 4 times greater than the concentration of ethylene used in the initial phase of the operation, and the corresponding optimized and safe concentration of oxygen.

Brief description of drawings

Figure 1 shows the selectivity (S) as a function of the concentration of ethylene ("C₂H₄, %") in the gas supply for fresh highly selective catalyst (F S-882) and aged highly selective catalyst ("S-882").

Figure 2 shows the activity ("T") as a function of the concentration of ethylene ("C₂H₄, %") in the gas supply for fresh highly selective catalyst (F S-882) and aged highly selective catalyst ("A S-882").

Figure 3 shows the selectivity (S) as a function of the concentration of ethylene ("C₂H₄, %") in the gas supply for fresh conventional catalyst (F S-860) and aged conventional catalyst ("A S-860").

Figure 4 shows the activity ("T") as a function of the concentration of ethylene ("C₂H₄, %") in the gas supply and for fresh conventional catalyst (F S-860) and aged conventional catalyst ("A S-860").

Detailed description of the invention

The term "aged " catalyst", as used here, means the catalyst during the operation reached old age, determined by cumulative production of ethylene oxide in excess of 0.01 CT ethylene oxide on m³catalyst and fresh catalyst" means a catalyst directly after its preparation or update, or the catalyst during the operation have not yet reached old age, as defined. Often aged catalyst is old enough to cause a decrease in selectivity S on at least a 2.5 mol%. and/or increased activity parameter of T for at least 15°where the selectivity S and the activity parameter of T are as defined here below.

Headspace (direct) the oxidation of ethylene to ethylene oxide can be carried out based on the air or on the basis of oxygen, see Kirk-Othmer''s Encyclopedia of ChemicalTechnology, 3rd ed., vol. 9 (1980), p. 445-447. In the processes on the basis of air or oxygen-enriched air is injected directly into the system, whereas in the processes based on oxygen use oxygen of high purity (>95% mol.) as a source of oxidant. Currently, the majority of installations for the production of ethylene oxide are units on the basis of oxygen, and this is site is titanium implementation of the present invention.

And processes on the basis of air, and processes based on oxygen demand discharge of exhaust flow in order to avoid accumulation of inert gases, although removal process flow based on the air much longer due to the large amount of nitrogen, which is constantly introduced. In any case, at least part of the ethylene always lost with the exhaust flow. The lost thus ethylene depends on exhaust flow (which, as noted above, less facilities-based oxygen), but also on the concentration of ethylene in the gaseous reaction mixture. Technical and economic conditions (including the price of ethylene) is determined for each individual installation optimized balance between the best characteristics of the catalyst and the least loss of ethylene with reset.

Further, in order to remain outside the ignition of the gas mixture, the oxygen concentration may be reduced as increases the concentration of ethylene. The actual intervals of safe work depend, apart from the composition of the gas (reagents and carrying gases), also from the conditions on a particular installation, such as temperature and pressure. More specifically, the maximum concentration of oxygen that can be used, i.e. oxygen Flammability limit, is reduced in the case of gas containing more than the high concentrations of ethylene and/or ethylene oxide, at a higher temperature and/or at higher applied pressure, and increases in the case of a gas containing a higher concentration of paraffins, such as methane and/or ethane. At each installation use the so-called equation of Flammability in order to determine the concentration of oxygen, which can be used with any given concentration, for example, ethylene. Equation Flammability can be represented graphically in a so-called curve of ignition.

"GHSV", or hourly average volumetric gas flow rate represents the number of units of volume of gas at standard temperature and pressure passing through one unit volume of the loaded catalyst per hour. Preferably the process is carried out at GHSV in the range of from 1500 to 10000. The reaction temperature preferably is in the range from 180 to 325°S, and the inlet pressure in the reactor is preferably in the range from 1000 to 3500 kPa.

On the performance of w, which represents the number of ethylene oxide produced per unit volume of catalyst (kg m³or grams per liter, etc) affect your temperature, pressure and gas velocity. Preferably the method according to this invention is carried out at a performance in the range of from 25 to 400 kg produced ethylene oxide us ³of catalyst per hour, in particular from 32 to 320 kg produced ethylene oxide on m³of catalyst per hour, for example at 200 kg produced ethylene oxide on m³of catalyst per hour.

The value of selectivity, expressed in mol%. educated target of ethylene oxide relative to the total number of converted ethylene at a given performance, w, will vary with the size of the actual performance w.

The value of the activity parameter of the T, which is the operating temperature, expressed in °needed to achieve a given performance w will also vary with the size of w.

In the preferred implementation of this invention, the gaseous reaction mixture contains ethylene in a concentration that is economically optimized balance between the characteristics of the catalyst (expressed at a given performance w selectivity S and option activity T), on the one hand, and losses expiring on reset ethylene, and oxygen in a concentration that meets security-related restrictions Flammability.

The optimal concentration of ethylene, calculated on the entire reaction mixture, which is used in the initial phase of the operation depends on the selected system, catalyst, reaction conditions and you the early performance. Preferably the ethylene concentration, calculated on the whole, the reaction mixture should be at most 50 mol%. More preferably, it should be in the range from 2 to 45 mol%, in particular from 2 to 40 mol%. ethylene concentration, generally used on installations operating on the air, in the range from 2 to 15 mol%, and with the concentration generally used on plants operating on the oxygen, in the range from 15 to 45 mol%, preferably from 15 to 40 mol%. of ethylene.

The term "reaction mixture"as used here, means that it takes into account the composition of the gas fed to the reactor, expressed in fractions, for example, in mol % or ppm by volume (ppm vol.), in relation to all of the supplied amount of gas.

In the advanced phase of the operation according to the present invention the ethylene concentration increases, preferably to a level of from 1.1 to 4 times higher concentrations of ethylene used in the initial phase of the operation. More specifically, it needs to be raised to a value from 5 to 30 mol%. ethylene, preferably from 10 to 20 mol%. Preferably the ethylene concentration is increased to at least 30 mol%, more preferably to at least 40 mol%, particularly preferably to at least 50 mol%. Preferably the ethylene concentration increases to at most 90 mol%, more preferably up to at most 80% of the mod is., particularly preferably up to at most 70 mol%.

In the advanced phase of the operation the ethylene concentration is raised, when the cumulative production of ethylene oxide exceeds 0,01 CT ethylene oxide on m³catalyst, where kt denotes 10⁶kg is Usually the ethylene concentration is raised, when the cumulative production of ethylene oxide will exceed 0.1 kt ethylene oxide on m³the catalyst, more typically, 0,3 CT ethylene oxide on m³catalyst, preferably of 0.5 kt ethylene oxide on m³catalyst, more preferably of 1.0 kt ethylene oxide on m³catalyst, especially a 1.5 CT ethylene oxide on m³of the catalyst. Often the ethylene concentration must be raised before cumulative production of ethylene oxide exceeds 50 kt ethylene oxide on m³catalyst, more often before cumulative production of ethylene oxide exceeds 10 kt ethylene oxide on m³catalytic Converter.

The increase in the concentration of ethylene can be single-stage or multi-stage, it may also include one or more gradual increases over a period of time, or a combination of stepwise and gradual increases.

In the process oxygen is preferably used in "the corresponding optimal oxygen concentration", which is defined as the concentration of oxygen, which PR is applied conditions of temperature and pressure and in combination with a selected concentration of ethylene provides optimum performance, at the same time avoiding the limits of ignition.

Typically, the concentration of oxygen used in the initial phases of operation, should be in a wide range from 6 to 12 mol%. all of the supplied gas stream.

Preferably in the advanced phase of the operation according to the present invention is used, the oxygen concentration should be reduced to a level of from 0.98 to 0.3 times the concentration of oxygen used in the initial phases of operation, and more specifically it should be reduced in size from 0.4 to 3.5 mol%, usually depending on the level at which the increased concentration of ethylene. Usually on any mole % absolute increase in the concentration of ethylene oxygen concentration should be reduced by the amount from 0.02 to 0.15 mol.% absolute, more typically from 0.05 to 0.1 mol.% absolute, for example, 0.08 mol.% an absolute. Usually any % relative increase in the concentration of ethylene relative decrease in oxygen concentration may be from 0.05 to 0.8%, more typically from 0.15 to 0.5%, for example 0,22%. Preferably the oxygen concentration is reduced to at most 10 mol%, more preferably up to at most 8 mol%. Preferably the oxygen concentration is reduced to at least 3 mol%, more preferably to at least 4 mol%.

Usually the change of oxygen concentration, if any, can be synchronous is m by changing the concentration of ethylene.

In addition to the ethylene and oxygen in the reaction mixture of the process according to this invention may contain one or more optional components, such as carbon dioxide, moderator of the gas phase and the balance inert gas.

Carbon dioxide is a byproduct of the oxidation of ethylene. Because often unreacted ethylene continuously recycle and because the concentration of carbon dioxide in the power of the reactor, which exceeds 15 mol%. will have an adverse effect on the catalyst activity, it is necessary to avoid the accumulation of carbon dioxide by the continuous removal of carbon dioxide from the recycle gas. This can be done by suuki (venting) and by continuous absorption of the formed carbon dioxide. Practically applicable are so small the current concentrations of carbon dioxide as 1 mol%., and in the future can be achieved even lower concentrations of carbon dioxide. The method according to the present invention does not depend on the presence or absence of carbon dioxide in the reaction mixture.

To improve the selectivity in the diet may be added to the vapor moderator catalyst suppressing the undesirable oxidation of ethylene to ethylene oxide to carbon dioxide and water. It is known that in this respect can be the effective many organic compounds, in particular, organic halides, and amines, ORGANOMETALLIC compounds and aromatic hydrocarbons. The preferred gas-phase moderators catalyst are organic halides, and they are effective, not suppressing the target reaction, when they are used in concentrations in the range of from 0.1 to 25 ppm vol., in particular from 0.3 to 20 ppm. of the total volume of the source gas.

The optimal concentration of gas-phase moderator of the catalyst may depend on the conditions of operation and the type of catalyst. Conventional catalysts have relatively flat curves selectivity for the moderator (i.e. the selectivity does not change in a wide range of concentrations of the moderator), and this property does not change during long-term operation of the catalyst. Therefore, the concentration of the moderator, you can choose more freely, and it may remain the same during the entire lifetime of the catalyst. In contrast, highly selective catalysts tend to give relatively steep curves of the moderator (i.e., the selectivity varies significantly with relatively small changes in the concentration of the moderator and has a pronounced maximum at the most advantageous or optimal concentration of the moderator). Moreover, this optimum moderator tends ISM is to apply during continuous operation. Therefore, the concentration of the moderator can be re-optimized during the operation, must be supported if the maximum achievable selectivity. In the initial phase of operation, the concentration of organic halides is usually in the range from 0.5 to 10 ppm vol., preferably from 2 to 8 ppm. of the total volume of the source gas. In the advanced phase of the operation, the concentration of organic halides is usually in the range from 2 to 25 ppm vol., preferably from 3 to 16 ppm. of the total volume of the source gas.

Preferred organic halides are₁-C₈-chlorohydrocarbons or bromopentanoate. More preferably they are selected from the group consisting of methyl chloride, ethylchloride, ethylene dichloride, ethylenedibromide, vinyl chloride, or a mixture thereof. The most preferred gas-phase the moderator of the catalyst are ethylchloride and ethylene dichloride.

Carrying inert gases typically present in the reaction mixture include different concentrations of nitrogen, argon and optionally saturated hydrocarbon, such as methane or ethane. Because neprevyshenie ethylene continuously recycle and add oxygen, it is necessary to avoid accumulation of the carrying gas. The method according to the present invention does not depend on the number of inert gases in the reaction mixture.

And in the initial phases of operation, and in the advanced phase of the operation, the optimal concentration of ethylene can be determined by serial measurement in terms of S and T for a given value of w characteristics of progressively increasing concentrations of ethylene in combination with the relevant safe concentrations of oxygen, until it will be impossible to achieve further improvements.

The material of the carrier supported on a carrier of catalysts based on silver can be selected from a range of common materials that are considered inert in the presence of raw materials and products under the reaction conditions for the oxidation of ethylene. Such conventional materials can be natural or synthetic and include oxides of aluminum, magnesium oxide, zirconium dioxide, silicon dioxide, silicon carbide, clays, pumice, zeolites, and charcoal. Alpha-alumina is the preferred material for use as the main ingredient in porous media.

The carrier is porous and preferably has a specific surface area measured by the BET method, of less than 20 m²/g, more specifically from 0.05 to 20 m²/, Preferably the specific surface of the carrier according to BET is in the range from 0.1 to 1, more preferably from 0.1 to 3.0 m²/, BET Method of measuring the specific surface area was described in detail Brunauer, Emmet and Teller in J. Am. Chem. Soc. 60 (1938), p.309-316.

Highly selective supported on a carrier, the catalyst on the basis of silver according to the present invention is a catalyst which, when used fresh, has 260°From a theoretical selectivity at zero output, S₀at least 6/7 or 85.7 percent. The value of S₀for this catalyst were found when the catalyst at 260°in the range of operating capacities w, receiving interval of values of selectivity S, corresponding to the range of operating capacity w. These values of S then interpolable to theoretical values of S at zero performance using the normal approximation algorithms curves, such as the algorithms proposed by MICROSOFT® Excel.

Supported on a carrier of highly selective catalysts based on silver for use in the present invention are registertask catalysts. Such catalysts are known from EP-B-266015. Generally speaking, they contain a catalytically effective amount of silver, a promoting amount of rhenium or its compounds, promoting amount of at least one additional metal or its compounds, and not battelino, copromotion number of copromotor rhenium, which may be selected from one or more of sulfur, phosphorus, boron and their compounds, refractory carrier. More specifically, at least one additional metal such registergui catalysts are selected from the group of alkali metals, alkaline earth metals, molybdenum, tungsten, chromium, titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium and germanium and mixtures thereof. Preferably at least one additional metal selected from alkali metals such as lithium, potassium, rubidium and cesium and/or alkaline earth metals such as calcium and barium. Most preferred is lithium, potassium and/or cesium.

The preferred number of components of such catalysts in the calculation of the element to the entire catalyst, are:

- silver - from 10 to 300 g/kg;

the rhenium is from 0.01 to 15 mmol/kg;

- additional metal or metals is from 10 to 3000 mg/kg and

- optional copromotor rhenium is from 0.1 to 10 mmol/kg

The obtained ethylene oxide may be recovered from the reaction mixture by known methods, for example, by absorption of the ethylene oxide from the output stream of the reactor water and, optionally, removing ethylene oxide from aqueous solution by distillation. At least part of the aqueous solution, with whom containing a series of ethylene oxide, can be used in the subsequent process of making ethylene oxide into the 1,2-diol or a simple ester 1,2-diol.

Ethylene oxide obtained by the present method, i.e. ethylene oxide, can be converted into 1,2-ethanediol or a simple ester of 1,2-ethanediol. Improved characterization of the catalyst is achieved by means of the present invention, leads to a more attractive process for obtaining ethylene oxide and at the same time to a more attractive process, which includes obtaining ethylene oxide and subsequent use of the obtained ethylene oxide to obtain 1,2-ethanediol or a simple ester of 1,2-ethanediol.

The conversion of 1,2-ethanediol or a simple ester of 1,2-ethanediol may include, for example, the reaction of ethylene oxide with water, usually using an acidic or basic catalyst. For example, to obtain predominantly 1,2-ethanediol and to a lesser extent ethers of 1,2-ethanediol ethylene oxide can interact with a 10-fold molar excess water from the reaction in the liquid phase in the presence of an acidic catalyst, for example of 0.5-1.0% wt. sulfuric acid based on the total weight of the reaction mixture at 50 to 70°and a pressure of 1 bar abs., or by reaction in the vapor phase at 130-240°and a pressure of 20-40 bar abs., preferably in the absence of catalyst. If the proportion of water is reduced, increasing the proportion of esters of 1,2-ethanediol in re klonoa mixture. Thus obtained esters of 1,2-ethanediol can be a fluids, triavir, tetraethyl and products further esterification. Alternative ethers, 1,2-ethanediol can be obtained by conversion of ethylene oxide with an alcohol, in particular with a primary alcohol, such as methanol or ethanol, replacing at least part of the water with alcohol.

1,2-Ethanediol and ethers, 1,2-ethanediol can be used in many industrial processes, for example, in the food industry, for manufacture of beverages, tobacco, cosmetics, thermoplastic polymers, thermosetting resin systems, detergents, heat transfer systems, etc.

The following examples will explain the invention.

Part I. the Catalysts

The catalyst And was an industrial catalyst for highly selective Shell type, as defined in EP-B-266015 containing rhenium promoter and copromotor rhenium and has a theoretical efficiency of S₀93% in fresh condition.

A comparative catalyst was a S-860 industrial catalyst Shell of conventional type, as described in US-A-5380697, not containing rhenium and copromotor rhenium and has a theoretical efficiency of S₀85% in fresh condition.

The above values of S₀was determined by collecting values selectively S when many space velocities, each time with 30% er who Elena, 8% oxygen, 5% carbon dioxide and 14 bar for both catalysts, the reaction temperature was 260°for catalyst a and 235°for catalyst, and backward extrapolation to infinite volume rate (i.e. work with zero performance).

Felt fresh and aged catalyst a and the comparative catalyst Century Aged catalyst And took with industrial installations, where it was used for 21 months, having in the amount of 2400 kg of ethylene oxide per liter of catalyst. Antique comparative catalyst were taken from industrial installations, where it was used for 34 months, having in the amount of 4500 kg of ethylene oxide per liter of catalyst. Both aged catalyst was taken from the middle of the respective tubes of the reactor. They were analyzed and found that they do not contain impurities.

Part II. Test method catalyst

Each experience from 1 to 5 g of the milled catalyst (0.8 to 1.4 mm) were loaded into a microreactor consisting of a U-shaped stainless steel tube of internal diameter 3 mm U-shaped tube was immersed in a bath of molten metal tin/bismuth (heat medium) and the ends of the tube were attached to the system is the flow of gases. The mass of catalyst and the flow rate of the incoming gas was regulated in such a way as to achieve a time volumetric gas velocity of 3300 ml of gas is per ml of catalyst per hour. The inlet gas was 1600 kPa.

In each experiment examined the influence of one fresh or aged catalyst of one of the seven concentrations of ethylene in the feed, when the adjustment of the volume flow rangerovers from 25 to 55 mol%, when optimized under other conditions of food and temperature. The oxygen concentration in the diet used in each experiment was the maximum allowed within the ignition and ranged from 9 to 6.5 mol%. The concentration of carbon dioxide was set at a normal level for each type of catalyst, i.e. a 3.5% for fresh highly active catalyst and 5.0% for aged highly active catalyst for the usual catalysts. The concentration of ethylchloride optimized in the range of 2.0 to 4.0 ppm. for fresh, highly selective catalyst, optimized in the range of from 3.0 to 7.0 ppm. for aged highly selective catalyst was set at 2.5 ppm. for fresh and aged conventional catalysts. Nitrogen ballast accounted for the remaining volume of the original mixture. The temperature in each experiment was set up, raising it gradually to achieve a constant performance w (mg ethylene oxide produced per ml of catalyst per hour). In accordance with normal industry practice and consistent throughput w was 200 kg/m³/h for svezhego aged catalyst S-882 and fresh catalyst S-860 and 160 kg/m ³/h for aged catalyst S-860.

Part III. Results

The results are shown in the following table (EO represents ethylene oxide), and Fig. 1-4. In Fig. 1-4, the percentage of oxygen was regulated in accordance with Flammability.

From these results it is clear that the aged catalyst S-882 particularly different from the fresh S-882 and S-860 and aged S-860 that its characteristics (selectivity, and activity) clearly improves when the ethylene concentration in the diet raise from 25 to 55 mol%. For fresh, high-activity catalysts the selectivity of the reaction for ethylene oxide did not change significantly when a higher concentration of ethylene was combined with a lower (i.e. safe) oxygen concentration, whereas for aged highly selective catalysts selectivity under these conditions substantially increased. Differences in the characteristics of the activity in conditions of high concentrations of ethylene and low oxygen concentration between fresh and aged highly selective catalysts have the same orientation, but less pronounced. It was found that, in contrast to the highly selective catalysts, aged and fresh traditional catalysts for the oxidation of ethylene do not show such obvious differences in their reactions to the Tav source gas mixture. Thus, increasing the ethylene content in the reaction gas mixture while reducing the oxygen content to stay below the Flammability limit, and significantly improves the selectivity and activity of the aged high-activity catalyst.

1. The method of vapor-phase oxidation of ethylene to ethylene oxide, comprising the reaction of a reaction mixture comprising ethylene and oxygen in the presence of supported on a carrier of highly selective catalysts based on silver, comprising a catalytically effective amount of silver, a promoting amount of rhenium or its compounds and the promoting amount of at least one additional metal or its compounds, through the implementation of the initial phase of the operation, which uses fresh catalyst, and the implementation of additional phases of the operation, when the cumulative productivity ethylene oxide exceeds 0,01 CT ethylene oxide on 1 m³catalyst, where specified in an additional phase of the operation increase the concentration of ethylene in the reaction mixture.

2. The method according to claim 1, wherein the additional phase of the operation the ethylene concentration increases when the cumulative productivity ethylene oxide exceeds 0,3 kt ethylene oxide per 1 m³catalytic Converter.

3. The method according to claim 2, in which additional phase of the operation the concentration of the ethylene increase, when the cumulative productivity ethylene oxide will exceed 0.5 kt ethylene oxide per 1 m³catalytic Converter.

4. The method according to claim 3, in which additional phase of the operation the ethylene concentration increases when the cumulative productivity ethylene oxide exceeds 1 kt ethylene oxide per 1 m³catalytic Converter.

5. The method according to any one of claims 1 to 4, in which the ethylene concentration increases to a value of from 1.1 to 4 times higher compared with the concentration of ethylene used in the initial phase of the operation.

6. The method according to claim 5, in which the concentration of oxygen used to reduce the magnitude component from 0.98 to 0.3 times as compared with the concentration of oxygen used in the initial phase of the operation.

7. The method according to any one of claims 1 to 6, which is supported on a carrier of highly selective catalyst on the basis of silver includes a catalytically effective amount of silver, a promoting amount of rhenium or its compounds, promoting amount of at least one additional metal or its compounds selected from alkali metals, alkaline earth metals, molybdenum, tungsten, chromium, titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium, germanium and mixtures thereof, and copromotion number of copromotor rhenium selected from one or more elements from among sulfur, fo the handicap, boron and its compounds, where in the calculation of the element to the entire catalyst, the amount of silver is in the range from 10 to 300 g/kg; the amount of rhenium is in the range from 0.01 to 15 mmol/kg; the amount of additional metal or metals is in the range from 10 to 3000 mg/kg; number of optional copromotor rhenium is in the range from 0.1 to 10 mmol/kg and where the carrier is porous, its surface area is in the range from 0.05 to 20 m²/g and the material of the carrier is mainly alpha-aluminum oxide.

8. The method according to claim 7, in which at least one additional metal includes lithium, potassium and/or cesium.

9. The method according to any one of claims 1 to 8, in which the moderator gas phase is present from 0.3 to 25 ppm. organic halide comprising chloropetalum or bromopentane₁-C₈.

10. The method according to claim 9, in which the organic halide is selected from methyl chloride, ethylchloride, ethylene dichloride, ethylenedibromide, vinyl chloride and mixtures thereof.

11. The method according to any one of claims 1 to 10, in which an additional phase of the operation the composition of the reaction mixture changed so that the mixture contained in the amount of from 5 to 30 mol.% more than the concentration of ethylene used in the initial phase of the operation.

12. Method for producing 1,2-ethanediol or the corresponding simple ether of 1,2-ethanediol, VK is uchumi obtaining ethylene oxide and the conversion of ethylene oxide to 1,2-ethanediol, or a simple ester of 1,2-ethanediol, characterized in that the ethylene oxide is produced by method of production of ethylene oxide according to any one of claims 1 to 11.