Method of perfecting process of producing ethylene oxide

FIELD: chemistry.

SUBSTANCE: invention pertains to ethylene oxide and to the method of obtaining 1,2-ethanediol or a simple ether of 1,2-ethanediol, from ethylene oxide, obtained using the proposed method. The process of producing ethylene oxide involves an epoxidation reactor system, containing a volume of a high octane epoxidation catalyst. The method involves replacing part of the volume of the high octane epoxidation catalyst with a volume of highly selective catalyst and modification of the process system so as to provide for initial raw materials of the reactor of the epoxidation system, with low concentration of carbon dioxide.

EFFECT: considerable improvement in the effectiveness of the system of producing ethylene oxide due to perfection of the process and operation of the existing production system.

13 cl, 5 dwg, 5 tbl, 3 ex

The present invention relates to improvement of an existing process for the production of ethylene oxide by modification of the reactor system.

Before the discovery of highly selective catalysts for epoxidation of ethylene used for the partial oxidation of ethylene to ethylene oxide, and in some cases even after the discovery of highly selective catalyst system of the process of production of ethylene oxide was developed based on the use of highly active catalysts for the epoxidation of ethylene. The use of highly active catalysts for the epoxidation of ethylene allows you to work at lower temperatures in the reactor to achieve this performance by ethylene oxide.

In recent years, developed new highly selective catalysts for epoxidation of ethylene, which compared to conventional highly active catalysts for the epoxidation of ethylene to provide the advantages of selective action. Such highly selective catalysts are described in U.S. patent No. 4761394 and 4766105. However, due to their lower activity of highly selective catalysts are used at higher reaction temperatures to achieve a certain yield of ethylene oxide.

Normal production of ethylene oxide in the General case includes a reactor epoxidase the Oia, the allocation system of ethylene oxide and removal of carbon dioxide. Such systems are actually connected to each other so as to provide partial oxidation of ethylene with oxygen in receipt of ethylene oxide and secretion of ethylene oxide. Carbon dioxide is an unwanted by-product of the epoxidation reaction, and it is usually removed from the production of ethylene oxide with a speed that almost matches the speed of its production, in order to prevent its accumulation in the system.

Normally, the production of ethylene oxide are designed for a definite type of the proposed epoxidation catalyst, and before the introduction of highly selective catalysts for many systems the production of ethylene oxide were designed for highly active catalysts for epoxidation. As used in this description with reference to the selectivity of the catalyst, the term "selectivity", S_wmeans molar percentage (%) formed the target of ethylene oxide from the total number of converted ethylene during this performance, w, for catalyst performance, defined as the number of ethylene oxide obtained per unit volume of the catalyst (for example, kg / m³) per hour. The definition of "activity", T_wused in this description in relation to activity and catalyst, mean temperature, which is necessary given the catalyst for this performance. Thus, high activity epoxidation catalyst is a catalyst that requires lower reaction temperature to obtain this output of ethylene oxide at a given quantity of catalyst in the epoxidation compared with alternative catalyst for the epoxidation. Highly selective epoxidation catalyst is a catalyst which at this temperature provides a higher percentage of conversion of the feedstock in ethylenoxide product than an alternative catalyst for the epoxidation.

With the development of highly selective catalysts found that in many cases there may be various economic and production advantages in the use of such highly selective catalysts in the production of ethylene oxide instead of highly active catalysts. In conventional systems the production of ethylene oxide, designed for the use of highly active catalysts for the oxidation of ethylene, can be achieved a great advantage when replacing a highly active catalyst for the selective catalyst for the oxidation of ethylene. However, due to differences in the characteristics of two types of catalysts system design is produced in the production of ethylene oxide, using a highly active catalyst may be such that it prevents a simple replacement of a highly active catalyst for the selective catalyst. As a highly active catalyst is usually used to lower the temperature of the reactor than for highly selective catalyst reactor system is often designed for lower operating temperatures and pressures. In addition, the number side of the carbon dioxide produced by the reaction of epoxidation, which uses a highly active catalyst, in contrast to the epoxidation reaction, which uses highly selective catalyst, can be much larger. This leads to higher concentrations of carbon dioxide in the raw material of the epoxidation reactor and facing the flow of the epoxidation reactor. Such differences in the concentration of carbon dioxide can affect the design and operation of the system of removal of carbon dioxide, as well as the epoxidation reaction and reactor system.

Thus, in the production process of ethylene oxide, designed for the use of highly active catalyst for the epoxidation, there is a need for the replacement of highly active catalyst for the selective catalyst that could vospolzovalis the advantages of such catalysts.

Other aspects, objects and the several advantages of the invention will become apparent in light of the following description.

In accordance with this invention, a method for improving the work of the existing production process of ethylene oxide, and the method includes:

loading the first feedstock reactor containing carbon dioxide in a first concentration, in the system of the epoxidation reactor, including the epoxidation reactor containing the first volume of highly active catalyst for the epoxidation;

deducing from said system reactor epoxidation first exit stream of the reactor epoxidation;

loading at least part of the first exit stream of the reactor epoxidation in the absorber of ethylene oxide, used to separate the specified first exit stream of the reactor epoxidation on the first stream recycling, containing carbon dioxide in the second concentration, and the first stream of ethylene oxide;

the separation of the specified first stream of recycle to the first separated portion and the first remainder;

ensuring the availability of systems remove carbon dioxide, which includes an absorber of carbon dioxide and the solvent regenerator, where the specified absorber of carbon dioxide is designed to receive dioxide containing opertaional gas for introduction to the contact specified containing carbon dioxide source gas with the spent solvent to obtain enriched solvent and the gas stream with a reduced content of carbon dioxide, and where the specified solvent regenerator is designed to receive the specified enriched solvent and separation of carbon dioxide and removal of specified waste solvent and a stream of gaseous carbon dioxide;

loading at least part of the first specified remaining in the specified system removal of carbon dioxide in the form specified containing carbon dioxide source gas to produce in the form of a specified gas stream with a reduced content of carbon dioxide of the second stream recycling, containing carbon dioxide in a third concentration, and obtaining as specified stream of carbon dioxide gas in the first flow of bleed dioxide;

combining at least the first part of this separated part and at least part of the second stream recycling with oxygen and ethylene to education as a result of this first feedstock reactor;

remove from the specified epoxidation reactor, at least part of the first volume of highly active catalyst for the epoxidation and replacement of its plug-in loading of the second volume of the highly selective epoxidation catalyst with obtaining the modified system of the epoxidation reactor;

loading the second feedstock reactor, the soda is containing carbon dioxide in the fourth concentration, which is lower than the specified first concentration of carbon dioxide in the specified modified system epoxidation reactor containing the specified removable loading;

deducing from this modified system reactor epoxidation second exit stream of the reactor epoxidation;

loading at least part of the second exit stream of the reactor epoxidation specified in the absorber of ethylene oxide, used to separate the specified second exit stream of the reactor epoxidation in the third stream recycling, containing carbon dioxide in the fifth concentration, and the second stream of ethylene oxide;

the separation of the specified third stream recycling to the second separated portion, if necessary, and the second remainder;

loading at least part of the second specified remaining in the specified system removal of carbon dioxide in the form specified containing carbon dioxide source gas to produce in the form of a specified gas stream with a reduced content of carbon dioxide of the fourth stream recycling, containing carbon dioxide in the sixth concentration, and obtaining as specified stream of carbon dioxide gas of the second flow of bleed carbon dioxide; and

combining at least part of this second separated h the STI, if it is, and at least part of the flow of the fourth recycle oxygen and ethylene to produce in the result of this second feedstock reactor.

The invention also provides a method of production of ethylene oxide, including the production of ethylene oxide by the process of the production of ethylene oxide, which is improved by using the proposed method.

Fig. 1 is a system diagram of the process of production of ethylene oxide.

Fig. 2 is a system diagram of production process of ethylene oxide Fig. 1 with a modified system of the epoxidation reaction.

Fig. 3 illustrates the improvement of the service life of the catalyst and selectivity highly selective catalyst with graphs based catalyst selectivity ("S", in %) when the performance of the aggregate performance for ethylene oxide ("P", in CT/m³) when using highly selective epoxidation catalyst (I) in conditions with relatively low concentration of carbon dioxide in the feedstock epoxidation in comparison with the traditional use of highly selective epoxidation catalyst ("II") and the traditional use of highly active catalyst ("III").

Fig. 4 illustrates the improvement of the service life of the catalyst and the reaction temperature with photosurface depending on the temperature of the coolant of the reactor ("T", in ° (C) from the aggregate performance for ethylene oxide ("P", in CT/m³to use highly selective epoxidation catalyst (I) in conditions with relatively low concentration of carbon dioxide in the feedstock epoxidation compared to the traditional application of highly selective catalyst ("II") and the traditional use of highly active catalyst ("III").

Fig. 5 represents graphs of the concentrations of carbon dioxide at the inlet of the reactor ("CO₂"in % mole.) from the aggregate performance for ethylene oxide ("P", in CT/m³), corresponding to values of selectivity and refrigerant temperature of the reactor shown in Fig. 3 and Fig. 4.

The inventive method involves the improvement of the existing system of production of ethylene oxide, which is designed for use epoxidation catalysts that are highly active, but usually less selective than some recently developed highly selective catalysts for epoxidation. In the system of production of ethylene oxide of the proposed method the epoxidation reactor contains the first volume of highly active catalyst for the epoxidation. This first volume of highly active catalyst for the epoxidation replace, partially or completely, the second volume vinicole the active catalyst.

Although this more selective catalyst provides a higher yield of ethylene oxide for a given ethylene feedstock with reduced output side of the carbon dioxide, the more selective the catalyst is less active than highly active catalyst, and, therefore, requires a higher reactor temperature. Such higher temperature of the epoxidation reactor is often not achievable with existing equipment epoxidation reactor due to various mechanical limitations in systems that use highly active catalyst.

But found that when using highly selective epoxidation catalysts in the production of ethylene oxide by the partial oxidation of ethylene with oxygen at a constant conversion or performance, the concentration of carbon dioxide in the raw material of the epoxidation reactor depends on the selectivity of the catalyst, and by reducing the concentration of carbon dioxide in the raw material of the epoxidation reactor can be achieved considerable lowering of the temperature of the reactor, resulting in the possibility of realization of the benefits of replacing a highly active catalyst for the selective catalyst. Also found that a significant improvement in the period when Urby catalyst can be obtained by reducing the concentration of carbon dioxide in the raw material of the epoxidation reactor.

Thus, the method may include, along with the removal of at least part of the first volume of highly active catalyst for the epoxidation reactor and replacing the second volume of the highly selective catalyst for obtaining the modified system of the epoxidation reactor, modified work or equipment, or both, the system of removal of carbon dioxide with the possibility of removal of carbon dioxide from the system of the production process of carbon dioxide so that provided the desired lower concentration of carbon dioxide in the raw material of the epoxidation reactor.

After replacing the highly active catalyst system of the reactor highly selective epoxidation catalyst, it is important that the concentration of carbon dioxide in the feedstock reactor containing ethylene, oxygen and carbon dioxide, was kept at a low or at least lower concentrations, for example less than 3% mole. based on the total number of moles of ethylene, oxygen and carbon dioxide in the raw materials of the reactor. From the point of view the most good results, the concentration of carbon dioxide in the raw materials of the reactor, supplied in the system of the epoxidation reactor containing highly selective catalyst should be less than 2% mole., predpochtitelnei than 1.5% mole., more preferably less than 1.25% mole. and most preferably less than 1% mole. based on the total number of moles of ethylene, oxygen and carbon dioxide in the raw materials of the reactor. Although most preferably, the concentration of carbon dioxide in the raw material for the epoxidation reactor containing highly selective catalyst, was as low as possible, there may be a practical lower limit, and this lower limit may be 0.1% mole. ethylene, oxygen, and carbon dioxide feedstock reactor, but it is more likely that the lower limit is 0.2 or 0.3 % mole.

For separation of ethylene oxide in the quality of the product output stream of the epoxidation reactor is loaded into the system's absorption of ethylene oxide used for the separation of ethylene oxide from the exit stream of the reactor epoxidation and to receive the stream of product of ethylene oxide, which contains ethylene, and the gaseous stream recycling, which contains unreacted ethylene, unreacted oxygen, carbon dioxide and inert compounds. Ethylenoxide product may also include the reaction by-products, such as, for example, carboxylic acids (organic acids, aldehydes, carbon monoxide and heavier hydrocarbons.

From the point of view of the present invention is important to ncentrate of carbon dioxide in the exit stream of the reactor epoxidation of the epoxidation reactor after replacing highly active catalyst for the selective catalyst was significantly lower than the concentration of carbon dioxide to such replacement. Decreased concentration of carbon dioxide in the exit stream of the reactor epoxidation may be the result of several factors, including, for example, a modified operation of the system of removal of carbon dioxide and low output side of the carbon dioxide resulting from the lower temperature of the epoxidation reactor due to the lower concentration of carbon dioxide in the feedstock reactor epoxidation of the considered process. The flow of gaseous recycle of the absorber of ethylene oxide after the replacement of highly active catalyst for the epoxidation reactor for the selective catalyst will have a concentration of less than 5% mole. from the gaseous stream recycling. Although most favorably to the specified concentration of carbon dioxide was as low as possible, the concentration of carbon dioxide in the gaseous stream recycling after replacing the reactor epoxidation catalyst selective catalyst can typically be in the range from 1 to 5% by mole., and more specifically it is in the range from 2 to 4% mole.

Removal of carbon dioxide from the system of the production process of ethylene oxide gaseous stream recycling can be divided into the separated part and the remaining part, and the part of the military part, if it is, flow of gaseous recycle is recycled back into the epoxidation reactor, and the remaining part of the flow of gaseous recycle load in the system of removal of carbon dioxide.

The share of the flow of gaseous recycle, recycled to the epoxidation reactor, relative to the remaining part of the stream recycling, which is loaded into the system removal of carbon dioxide depends on many factors, including, for example, on the number side of the carbon dioxide obtained in the epoxidation reaction, and the efficient recovery of carbon dioxide through the system of removal of carbon dioxide. After replacing the catalyst for the epoxidation of epoxidation reactor with highly active catalyst for highly selective catalyst for the inventive method requires a reduction in the concentration of carbon dioxide in the gaseous stream recycling, resulting in a lower concentration driving force for the separation of carbon dioxide through the system of removal of carbon dioxide. Thus, the ratio of the flow of gaseous recycle the remaining part is reduced due to the need to load more raw materials in the removal of carbon dioxide after replacing the catalyst. Accordingly, after the replacement of the catalyst remaining stream recycling loaded in absor the EP of carbon dioxide, the entire stream recycling coming out of the absorber of ethylene oxide, can typically be in the range from 0.3 to 1, but is preferably from 0.4 to 1, most preferably from 0.5 to 1.

The higher the rate at which the remaining part of the gaseous stream recycling is loaded into the absorber of carbon dioxide, may require some structural changes in the absorber of carbon dioxide removal system of carbon dioxide, such as, for example, modification of the internal structure of the absorber of carbon dioxide, so as to provide a greater area of contact surface for contacting the spent solvent containing carbon dioxide feedstock. For example, within the contact zone defined by the absorber of carbon dioxide, there may be used a material with a high surface area to surface area contact within the absorber of carbon dioxide after replacing the catalyst for the epoxidation epoxidation reactor high activity for the selective catalyst was greater than before the substitution. An alternative to changing the internal design of the existing absorber of carbon dioxide is to install one or more additional absorbers of carbon dioxide, United in the operating mode in parallel with susestudio the absorber and is able to take in the view containing carbon dioxide gaseous feedstock remaining portion of the gaseous stream recycling.

System for removal of carbon dioxide is a system of solvent extraction, which includes an absorber of carbon dioxide and the solvent regenerator. The spent solvent is loaded into the absorber of carbon dioxide and injected into contact with the remaining part of the stream of gaseous recycle loaded into the absorber. Of the absorber of carbon dioxide out of enriched carbon dioxide solvent and the gaseous stream with reduced content of carbon dioxide. The gaseous stream with reduced content of carbon dioxide recycle back into the epoxidation reactor where it is mixed with the separated part of the stream of gaseous recycle, oxygen and ethylene with the receipt of raw materials to the epoxidation reactor.

Although some systems remove carbon dioxide from existing systems in the production process of ethylene oxide can meet the growing demands arising from the modification of the system of the epoxidation reactor due to the replacement of highly active catalyst for the selective catalyst, many systems remove carbon dioxide are not able to do it. Typically, as noted earlier, in the modification of epoxidation reactor by replacing the highly active catalyst for the selective catalyst concentration of carbon dioxide in the outcome of the om raw materials of the reactor should be reduced to get the most good results from the use of highly selective catalyst. This requires a lower concentration of carbon dioxide in the flow of the recycling process, resulting in a lower difference of concentrations between the initial material removal system of carbon dioxide and extraction solvent, which makes more difficult the extraction of carbon dioxide from a stream recycling.

In systems remove carbon dioxide used absorbent solvent can be an aqueous solution of a carbonate of an alkali metal such as sodium carbonate and potassium carbonate. The inventive method involves the modification of the solvent used in the removal of carbon dioxide of the invention, by creating a certain concentration of the activator or catalyst in the spent solvent. Such an activator or catalyst changes the characteristics of the mass transfer in solvent in order to improve the absorption and desorption of carbon dioxide from the remaining gaseous recycle loaded in the removal of carbon dioxide. Metavanadate potassium is an example of one suitable activators which can be used as an additive to the solvent removal system of carbon dioxide.

By modification or operation or the design of the system beats the population of carbon dioxide receive a reduced concentration of carbon dioxide in the feedstock reactor epoxidation of the proposed method. The concentration of carbon dioxide in the gaseous stream with reduced content of carbon dioxide after the replacement of highly active catalyst reactor highly selective epoxidation catalyst may comprise less than 2% mole. based on the entire flow; however, for the proposed method it is important that the concentration of carbon dioxide was as low as possible, preferably less than 1.5% mole., more preferably less than 1% mole. The usual interval for the concentration of carbon dioxide is from 0.1 to 2% mole., or from 0.15 to 1.75% mole., or from 0.2 to 1.5% mole.

Table 1 below shows a typical concentration of carbon dioxide (% mole.) in a variety of process flows in the system process ethylene production before and after the removal of highly active catalyst and replace it with a highly selective catalyst.

As a highly active catalyst, and highly selective catalyst, referred to in this description are catalysts based on silver on the carrier, but the two catalyst have different technological characteristics.

The material of the catalysts based on silver on the carrier can be selected from a wide range of porous media, in particular materials that are considered to be inert in the presence of the feedstock oxidation of ethylene, the reaction products and the conditions for this reaction. Such materials may be natural or artificial, and they can include aluminum oxide, magnesium oxide, zirconium dioxide, silicon dioxide, silicon carbide, clays, pumice, zeolites, and charcoal. Alpha-aluminum oxide which is the preferred material for use as the main ingredient in porous media.

The material of the carrier is porous and preferably has a specific surface area determined in accordance with the BET method, of less than 20 m²/g, more specifically from 0.05 to 20 m²/, Preferably the surface area of the carrier on BET is in the range from 0.1 to 10 m²/g, more preferably from 0.1 to 3.0 m²/, Method of determination of specific surface area by BET is described in detail in the publication of Brunauer, Emmet and Teller, J. Am. Chem.Soc. 60 (1938) 309-316.

Highly selective catalyst on the basis of silver on the carrier according to this invention may be a catalyst that has the original selectivity equal to at least 85%, preferably at least 86%, most preferably at least 87%. On the other hand, the initial selectivity of highly active catalysts based on silver on the carrier is less than the original selectivity highly selective catalysts based on silver on the carrier, and preferably the initial selectivity of highly active catalysts based on silver on the carrier can be less than 85%. However, consider that from a practical point of view, a highly active catalyst will have some minimal selectivity. It is considered, what is the minimum value of the selectivity is at least 78%.

The term "initial selectivity", the use of which has been created in this description, means the selectivity of this catalyst, when it is fresh and unused. It is known that the catalyst may lose activity during use. The initial selectivity of this catalyst is determined by measuring the selectivity of the catalyst using standard methods of tests. In this standard test method milled catalyst (particle size of 1.27-1,81 mm, i.e. the fraction of sieve hole size 14-20 mesh) placed inside a U-shaped stainless steel tube with a diameter of 6.35 mm (1/4 inch) of the microreactor operating in certain specific process conditions. Standard feedstock containing 30% mole. ethylene, 7% mole. carbon dioxide and 8.5% mole. oxygen and 54,5% mole. nitrogen is introduced into the microreactor with a gauge pressure 1447 kPa (gauge pressure of 210 psig) and with such speed that provides volumetric feed rate of the gaseous mixture 3300 h^-1. Selectivity, Sw, and activity, Tw, to determine the capacity at which the yield of ethylene oxide is 200 kg of ethylene oxide per hour per cubic meter of catalyst. Selectivity is expressed as a molar percentage (% mole.), and the activity present in the temperature values in degrees Celsius.

In addition to differences in the measured catalytic properties of high-level and Sokolenko catalysts may also be differences in the types and quantities of compounds, representing the promoters of the catalysts used in these two types of catalysts. One such difference is that highly selective catalysts of this invention include rhenium promoting component, while, on the other hand, highly active catalysts, if and contain a rhenium component, a minor or epromoterscom number. In addition to rhenium component of highly selective catalysts may optionally contain the promoting amount of a promoter based on an alkali metal or an additional metal promoter, or both of these supplements. Suitable highly selective catalysts are described in U.S. patent No. 4761394 and 4766105.

Thus, highly selective catalysts comprise a carrier material, a catalytically effective amount of silver, a promoting amount of rhenium and, optionally, a promoting amount of one or more alkali metals and, optionally, a promoting amount of one or more metal promoters. The amount of silver in a highly selective catalyst is in the range of catalytically effective amounts up to 40% of the mass. based on the total weight of the catalyst. Preferably the amount of silver may be in the range from 1 to 30 wt%. based on bwuu mass of catalyst and most preferably from 5 to 20 wt. -%

The amount of rhenium in the highly selective catalyst is promoting a number, usually located in the interval from a minimum of promoting amount of up to 20 micromol of rhenium per gram of catalyst. The preferred amount of rhenium in the highly selective catalyst is in the range from 0.1 to 10 micromol per gram, more preferably from 0.2 to 5 micromol per gram of total catalyst or, alternatively, from 19 to 1860 ppm, preferably from 37 to 930 hours/million based on the total weight of the catalyst.

The amount of alkali metal in a highly selective catalyst, if present, is promoting a number, usually located in the interval from a minimum of promoting amount of up to 4000 ppm based on the total weight of the catalyst (mass ppm - hours/million mass.). Preferably the amount of alkali metal, when one is present, is in the range from 10 to 3000 hours/million mass., more preferably from 15 to 2000 hours/million mass., even more preferably from 20 to 1500 hours/million masses.

Optional additional metal promoter is highly selective catalyst can be selected from the group of metals comprising sulfur, molybdenum, tungsten, chromium and mixtures of two or more of them. The amount of additional metal about Otarov in highly selective catalyst, if present, usually is in the range from 0.1 to 10 mmol per kilogram of total catalyst, and preferably from 0.2 to 5 mmol per kilogram of total catalyst.

As a highly active catalyst, besides the fact that it differs from the highly selective catalyst, is less selectivity, as described above, it usually does not contain rhenium promoter, but it may contain one or more promoters on the basis of the alkali metal. Thus, a highly active catalyst preferably may include a carrier material, a catalytically effective amount of silver and a promoting amount of alkali metal, but does not contain the promoting amount of rhenium. Thus, a highly active catalyst can also essentially be composed of a catalytically effective amount of silver, a promoting amount of alkali metal and the material of the carrier. Examples of suitable high-activity catalysts are described in U.S. patent No. 5380697.

Component of silver may be present in a highly active catalyst in amounts in the range from catalytically effective amount up to 40% of the mass. based on the total weight of the catalyst. However, preferably the silver is present in an amount in the range from 1 to 30 wt%. and most preferably from 5 to 20 wt. -%

Component SEL knogo metal may be present in a highly active catalyst in amounts in the range from promoting amount of up to 4000 hours/million masses. Preferably the alkali metal is present in an amount in the range from 10 to 3000 hours/million masses. and more preferably from 15 to 2000 hours/million masses.

Suitable reaction conditions for the epoxidation method of the present invention may include a reactor temperature in the range from 180 to 320°With, but found that the inventive method provides an opportunity to work in the area of the epoxidation reactor at lower temperatures without loss of selectivity highly selective catalyst. Indeed, the lower operating temperature of the reaction provided by the claimed method, leads to an increase of the duration of highly active catalyst and, consequently, to improve the economic efficiency of the production process of ethylene oxide. A more preferred range of temperature of the reactor is from 190 to 310°S, most preferably from 200 to 300°C. the Preferred reaction pressure is from atmospheric pressure to 35 bar. Volumetric hourly rate of the gas is in the range of from 1500 to 10000 h^-1.

With regard to Fig. 1, it presents the diagram of a typical system of the production process of ethylene oxide 10, which includes a system of epoxidation reactor 12, the system of allocation of ethylene oxide or of ethylene oxide absorber 14 and removal of carbon dioxide 16. System Rea the Torah epoxidation 12 includes the epoxidation reactor 18, which provides a means for shielding the flow of raw materials containing oxygen, ethylene and carbon dioxide, with the epoxidation catalyst under suitable reaction conditions, epoxidation, resulting in the formation of ethylene oxide. The epoxidation reactor 18 determines the area of the epoxidation reactor and contains the first volume of highly active catalyst for the epoxidation.

System for removal of carbon dioxide 16 includes an absorber of carbon dioxide 20 and the solvent regenerator 22. The absorber of carbon dioxide 20 defines the zone of absorption of carbon dioxide and provides a means for receiving, containing carbon dioxide gas with a lean solvent so as to form a rich solvent containing carbon dioxide, and the gas stream with a reduced content of carbon dioxide. The solvent regenerator 22 determines a regeneration zone of the solvent and provides a carbon dioxide-rich solvent, so that a stream of carbon dioxide and depleted in solvent, which is used as raw material for the absorber of carbon dioxide 20.

When the system is in the production process of ethylene oxide 10, which is designed to use a highly active catalyst for the epoxidation, the first feedstock reactor, with whom containing a series of carbon dioxide in the first concentration, download in the epoxidation reactor 18 through line 24, where in the epoxidation reactor 18, the first feedstock reactor comes into contact in a suitable reaction conditions epoxidation with highly active catalyst for the epoxidation.

The first exit stream of the reactor epoxidation 18 out of the epoxidation reactor 18 system epoxidation reactor 12 and loaded into the absorber of ethylene oxide 14 through line 26. The absorber of ethylene oxide 14 defines the zone of absorption of ethylene oxide and provides a means to probe the absorption solvent, such as water, with the first outgoing flow reactor epoxidation and gives the first stream recycling and the first stream of ethylene oxide. Absorption solvent is introduced into the absorber of ethylene oxide 14 through pipe 28, where in the absorber 14 ethylene oxide is introduced into contact with the first output stream of the epoxidation reactor. The first stream of ethylene oxide, containing absorption solvent and ethylene oxide, leaves of ethylene oxide absorber 14 through line 30 and the first stream recycling, containing carbon dioxide in the second concentration, comes from of ethylene oxide absorber 14 through line 32 into the recirculation compressor 34. In addition to the carbon dioxide first stream recycling also contains ethylene, oxygen and inert compounds.

Recir blaziny compressor 34 determines the compression zone and provides means for compressing a first stream recycling. Download the compressed first stream of recycle passes from the recirculation compressor 34 through line 36. The first separated portion of the compressed first stream of recycle passes through the pipe 38 and then through the pipeline 40, where it is combined with oxygen introduced through line 42, and ethylene is introduced through line 44.

The remaining part of the compressed first stream recycling is loaded into the absorber of carbon dioxide 20 system removal of carbon dioxide 16 through conduit 46 in the form containing carbon dioxide of the gaseous feedstock. Go through the pipe 48, the gas stream with a reduced content of carbon dioxide is the second stream recycling, containing carbon dioxide in a third concentration. The second stream of recycle passes into the pipe 40, where it is mixed with the first allocated part of the first compressed stream recycling, oxygen and ethylene, respectively, are introduced into the pipe 40 through the pipes 38, 42 and 44. Combining these streams form a first feedstock reactor loaded into the epoxidation reactor 18 through line 24. The first flow of bleed carbon dioxide containing carbon dioxide, is released in the form of a stream of carbon dioxide from the solvent regenerator 22 system removal of carbon dioxide 16 through line 50.

That cases the Fig. 2, it shows a typical system for the production of ethylene oxide 100 modified in accordance with the present invention. To improve the system operation process of the production of ethylene oxide 10 in Fig. 1, the system of the epoxidation reactor 12 is modified by removing at least part of the first volume of highly active catalyst contained in the epoxidation reactor 18, and replace it with a second volume of the highly selective catalyst for obtaining the modified system of the epoxidation reactor 112 with modified epoxidation reactor 118, as shown in Fig. 2. In order to replace the catalyst, the flow of the first feedstock reactor in the epoxidation reactor 18 is stopped to provide a catalyst removal and replacement.

After removal of the highly active catalyst from the reactor epoxidation 18 and replacing it with highly selective catalyst for the second feedstock reactor containing carbon dioxide in the fourth concentration, load in the epoxidation reactor 118 modified system of the epoxidation reactor 112 through line 124. Within the epoxidation reactor 118 second feedstock reactor comes into contact under suitable reaction conditions epoxidation with the selective epoxidation catalyst.

The second output is the overall flow of the epoxidation reactor is removed from the epoxidation reactor 118 modified system of the epoxidation reactor 112 and loaded into the absorber of ethylene oxide 114 through line 126. The absorber of ethylene oxide 114 defines a zone of absorption of ethylene oxide and provides a means to probe the absorption solvent, such as water, with the second output stream of the reactor epoxidation and gives the third stream recycling and the second stream of ethylene oxide. Absorption solvent is introduced into the absorber of ethylene oxide 114 through pipe 128, where the absorber of ethylene oxide 114 is inserted into contact with the second output stream of the epoxidation reactor. The second stream of ethylene oxide, containing absorption solvent and ethylene oxide, leaves the absorber of ethylene oxide 114 through line 130, and the third stream recycling, containing carbon dioxide in the fifth concentration comes from absorber of ethylene oxide 114 through line 132 to the recirculation compressor 134. In addition to carbon dioxide the third stream recycling also contains ethylene, oxygen and inert compounds.

The recirculation compressor 134 determines the compression zone and provides means for compression of the third stream recycling. Download the compressed third stream of recycle passes through the pipe 136. The second separated portion, if any, of the compressed third stream of recycle passes through the pipe 138 and then through the pipeline 140, where it is combined with oxygen introduced through line 142, and ethylene is introduced through line 144./p>

The remaining third part of the compressed stream recycling is loaded into the absorber of carbon dioxide 120 system removal of carbon dioxide 116 through line 146, in the form containing carbon dioxide of the gaseous feedstock. Go through the pipe 148 the gas stream with a reduced content of carbon dioxide is the fourth stream recycling, containing carbon dioxide in the sixth concentration. The fourth stream recycling takes place in the pipeline 140, where it is mixed with the second separate part of the compressed third stream recycling, oxygen and ethylene, respectively, are introduced into the pipe 140 through pipelines 138, 142 and 144. Combining these streams form a second feedstock reactor loaded into the epoxidation reactor 118 through line 124. The second stream of bleed carbon dioxide containing carbon dioxide, is released in the form of a stream of carbon dioxide from the solvent regenerator 122 system removal of carbon dioxide 116 through line 150.

Ethylene oxide, obtained the advanced method, can be converted into 1,2-ethanediol, a simple ester of 1,2-ethanediol or ethanolamine. Since the invention leads to a more profitable method of production of ethylene oxide, it simultaneously leads to a more attractive method, which includes obtaining the ethyl the oxide in accordance with this invention and subsequent use of ethylene oxide for the production of 1,2-ethanediol, simple ether of 1,2-ethanediol and/or ethanolamine.

The conversion of 1,2-ethanediol or a simple ester of 1,2-ethanediol may include, for example, the interaction of ethylene oxide with water at the appropriate acid or basic catalyst. For example, to obtain predominantly 1,2-ethanediol and, to a lesser extent, simple ether of 1,2-ethanediol ethylene oxide may be introduced into reaction with a tenfold molar excess of water in the liquid-phase reaction in the presence of an acid catalyst, for example of 0.5-1.0% of the mass. sulfuric acid based on the total weight of the reaction mixture at 50 to 70°and an absolute pressure of 1 bar or in gas-phase reactions in 130-240°and an absolute pressure of 20-40 bar, preferably in the absence of catalyst. If the proportion of water decreases, the number of ester 1,2-ethanediol in the reaction mixture increases. Ethers, 1,2-ethanediol, thus obtained, can be a simple diesters, treviri, therefire or subsequent esters. On the other hand, ethers, 1,2-ethanediol can be obtained by transformation of ethylene oxide with an alcohol, in particular with a primary alcohol, such as methanol or ethanol, by replacing at least part of the water with alcohol.

The transformation in ethanolamine may include, for example, the interaction of ethylene oxide with ammonia. Can be used Bessa the hydrated or aqueous ammonia, although best get monoethanolamine is typically used anhydrous ammonia. Methods that can be used for the conversion of ethylene oxide in ethanolamine described, for example, in the publication US-A-4845296.

1,2-Ethanediol and a simple ether of 1,2-ethanediol can be used in various fields of industry, for example in the food industry, beverages, tobacco products, cosmetic products, thermoplastic polymers, capable of curing polymer systems, detergents, heat exchange systems, etc. Ethanolamine can be used, for example, when processing ("elevation") of natural gas.

The following examples 1 and 2 are intended to illustrate some of the benefits of using highly selective catalyst under relatively low concentration of carbon dioxide in the raw material for epoxidation. The following example 3 is intended to illustrate some of the advantages of the present invention and by no means, as is implied, does not restrict the scope of the invention.

EXAMPLE 1

Highly selective catalyst containing silver and a promoting amount of rhenium, lithium, cesium and sulfur on alpha-aluminum oxide, feel upon receipt of ethylene oxide from ethylene and oxygen. For this sample of crushed catalyst is loaded into the U-shaped Rea is operating a stainless steel tube. The tube is immersed in a bath of molten metal (medium heat) at 180°and With the ends attached to the gas supply system. The gas mixture passed through the catalyst bed parallel. A lot of the used catalyst and the flow rate at the inlet adjusted so as to obtain a volumetric hourly rate of the gas 3300 nl/(l·h). The absolute pressure of the incoming gas is 1550 kPa.

The composition of the gas mixture regulate to obtain the following composition: 30% battilana, 8% oblitarate, 1% obliged carbon, and 2.5 parts by volume per million (volume ppm - OBC/million) ethylchloride, the rest is nitrogen.

The temperature of the catalyst layer increases at a rate of 10°per hour to 225°and then the temperature is set to be achieved by the conversion of oxygen to 40% mole. The concentration of ethylchloride in the gaseous mixture is brought to 2.5 OBC/million for optimum selectivity to ethylene oxide. The catalyst activity is expressed as the temperature at which achieved 40%molar conversion of oxygen (t); selectivity is the selectivity at a temperature of t. During the experiment, the catalyst undergoes decomposition, and to maintain a constant degree of conversion of 40% mole. the temperature is gradually increased. The results are presented in table 2.

In three similar cf is niteljnykh experiments, the concentration of carbon dioxide in the gas mixture is from 5 to 7% vol. instead of 1% vol. The average value of the three comparative experiments are also presented in table 2.

The results presented in table 2 clearly show that a lower concentration of carbon dioxide in the raw material of the epoxidation reactor improves the properties of the highly selective catalyst associated with its activity, selectivity and lifetime.

EXAMPLE 2

The calculated sample represents the data obtained using own models to predict properties of highly selective epoxidation catalyst in terms of working with an hourly space velocity 4700 nl/(l· h), a gauge pressure of 21.7 bar and performance 184 mg/(m³·h) for feedstock reactor containing 25% mole. ethylene and 8% mole. the oxygen. The model is based on the correlation data on the actual properties of the catalysts, collected from numerous sources, such as data on activity for microreactors, the data for the pilot plants, and other sources of data on the properties of the catalyst.

Fig. 3 represents the selectivity highly selective epoxidation catalyst as a function of aging of the catalyst based on the total performance of the ethylene oxide, represented ton/m³for the respective concentrations of carbon dioxide in the original reaction mixture, is shown in Fig. 4. The graphs show that there is a clear link between the life of the catalyst and the initial concentration of carbon dioxide and between the selectivity and the initial concentration of carbon dioxide. As shown in Fig. 3, the speed reduction catalyst selectivity in the processing of raw materials with the concentration of carbon dioxide of less than 1% mole. (curve I) is significantly lower than the rate of decrease in selectivity of the catalyst in the processing of raw materials containing carbon dioxide more than 4% mole. (curve II). You may also notice that the original high selectivity is selectinga catalyst is higher in the case when the concentration of carbon dioxide in the feedstock is less than 1% mole., unlike the feedstock with the concentration of carbon dioxide more than 4% mole. The presented data show that significant advantages in selectivity and lifetime of highly selective epoxidation catalyst can be obtained in the processing of raw materials epoxidation reactor with a low concentration of carbon dioxide. Other comparative data refer to the use of highly active catalyst, operating at the concentration of carbon dioxide more than 4% mole. (curve III).

Fig. 4 represents the temperature of the coolant of the reactor as a function of aging of the catalyst used in the epoxidation reaction for the respective concentrations of carbon dioxide in the raw materials shown in Fig. 5. The refrigerant temperature of the reactor is close to the reaction temperature. Data indicate that the rate of loss of activity of the epoxidation catalyst in the method of the present invention, used in the processing of raw materials epoxidation reaction with a low concentration of carbon dioxide, less than 1% mole. (curve I), significantly below the rate of loss of activity of the epoxidation catalyst used in the processing of raw materials with a higher concentration on the carbon monoxide, than in the method of the present invention (curve II). The data presented show that the stability of the highly selective epoxidation catalyst, represented as the rate of decrease in the activity of the catalyst is greatly improved when using the method of the present invention, which includes the processing of raw materials epoxidation reaction with a very low concentration of carbon dioxide. Additional comparative data refer to the use of highly active catalyst, operating at the concentration of carbon dioxide more than 4% mole. (curve III).

EXAMPLE 3

This current example provides selected information related to the concentrations of carbon dioxide in multiple threads, in the case of a hypothetical system of the production process of ethylene oxide with capacity of 800 tons per day, which uses a highly active catalyst for the epoxidation, and in the case of the same system after such a highly active catalyst for the epoxidation replaced by the selective epoxidation catalyst. Also presents the ratio of the number of raw materials loaded in the system process after replacement of the catalyst and before the replacement of the catalyst, and presents the ratio of the yield of ethylene oxide after replacement of the catalyst and to replace the cat who lyst. Data are presented on the basis of the output of their own model of a hypothetical system of the production process of ethylene oxide. In the calculations in the case of technological systems using highly selective catalyst, the assumption was made that the removal of carbon dioxide loaded 100% of the flow of recycling of ethylene oxide absorber, and in the case of the technical system using a highly active catalyst for 25% of the flow of recycling of ethylene oxide absorber, as implied, is loaded into system removal of carbon dioxide.

The data presented above in tables 3 and 4 show that the inventive method provides a significant improvement in the efficiency of the production of ethylene oxide. For this performance of ethylene oxide is a significant reduction in the number and the initial raw materials, consumed in its production. The ethylene consumption of raw materials decreased by 7.9%, and the oxygen consumption of raw materials decreased by 24.2%. Such reduction in the consumption of raw materials provide huge economic benefits that arise from the proposed method.

Although the present invention is described using a preferred variant implementation, reasonable changes and modifications feasible for professionals in this field. Such changes and modifications are within the scope of the described invention and the appended claims.

1. The method of producing ethylene oxide, which includes:

loading the first feedstock reactor containing carbon dioxide in a first concentration, in the system of the epoxidation reactor, including the epoxidation reactor containing the first volume of highly active catalyst for the epoxidation;

deducing from said system reactor epoxidation first exit stream of the reactor epoxidation;

loading at least part of the first exit stream of the reactor epoxidation in the absorber of ethylene oxide, used to separate the specified first exit stream of the reactor epoxidation on the first stream recycling, containing carbon dioxide in the second concentration, and the first is Otok of ethylene oxide;

the separation of the specified first stream of recycle to the first separated portion and the first remainder;

support removal of carbon dioxide, which includes an absorber of carbon dioxide and the solvent regenerator, where the specified absorber of carbon dioxide provides reception containing carbon dioxide feed gas and the introduction to the contact specified containing carbon dioxide feed gas with a lean solvent to obtain enriched solvent and the gas stream with a reduced content of carbon dioxide and where the specified solvent regenerator is designed to receive the specified enriched solvent and separation of carbon dioxide and removal of specified depleted solvent and a stream of gaseous carbon dioxide;

loading at least part of the first specified remaining in the specified system removal of carbon dioxide in the form specified containing carbon dioxide feed gas to produce in the form of a specified gas stream with a reduced content of carbon dioxide of the second stream recycling, containing carbon dioxide in a third concentration, and obtaining as specified stream of carbon dioxide gas in the first flow of bleed dioxide;

combining at least h is STI specified first separated part and, at least part of the second stream recycling with oxygen and ethylene to education as a result of this first feedstock reactor;

remove from the specified epoxidation reactor, at least part of the first volume of highly active catalyst for the epoxidation and replacement of its plug-in loading of the second volume of the highly selective epoxidation catalyst with obtaining the modified system of the epoxidation reactor;

loading the second feedstock reactor containing carbon dioxide in the fourth concentration, which is lower than the specified first concentration of carbon dioxide in the specified modified system epoxidation reactor containing the specified removable loading;

deducing from this modified system reactor epoxidation second exit stream of the reactor epoxidation;

loading at least part of the second exit stream of the reactor epoxidation specified in the absorber of ethylene oxide, used to separate the specified second exit stream of the reactor epoxidation in the third stream recycling, containing carbon dioxide in the fifth concentration, and the second stream of ethylene oxide;

the separation of the specified third stream recycling to the second division of the ing part, if you want, and the second remainder;

loading at least part of the second specified remaining in the specified system removal of carbon dioxide in the form specified containing carbon dioxide feed gas to produce in the form of a specified gas stream with a reduced content of carbon dioxide of the fourth stream recycling, containing dioxide in the sixth concentration of carbon, and obtaining as specified stream of carbon dioxide gas of the second flow of bleed carbon dioxide; and

combining at least part of this second separated parts, if any, and at least part of the flow of the fourth recycle oxygen and ethylene to produce in the result of this second feedstock reactor.

2. The method according to claim 1, where the fourth concentration of carbon dioxide is less than 3% based on the total number of moles of ethylene, oxygen and carbon dioxide in the raw materials of the reactor.

3. The method according to claim 2, where the fourth concentration of carbon dioxide is in the range from 0.1 to less than 2% based on the total number of moles of ethylene, oxygen and carbon dioxide feedstock reactor

4. The method according to claim 3, where the fourth concentration of carbon dioxide is in the range from 0.2 to less than 1.5% based on the total number of moles of ethylene oxygen and carbon dioxide in the raw materials of the reactor.

5. The method according to any one of claims 1 to 4, where highly selective epoxidation catalyst is a catalyst based on silver, which includes rhenium promoting component, and a highly active catalyst is a catalyst based on silver, which does not contain rhenium promoting component or contains lepromatous the amount of the rhenium component.

6. The method according to claim 5, where the highly selective epoxidation catalyst comprises a material carrier alpha-alumina, the amount of silver is in the range from 1 to 40 wt.% and the amount of rhenium is in the range from 0.1 to 10 mmol per 1 g based on the total weight of the catalyst, and where highly active catalyst contains as the material carrier of alpha-alumina, and the amount of silver is in the range from 1 to 40 wt.%.

7. The method according to claim 1, where the specified depleted solvent contains an aqueous solution of a carbonate of an alkali metal.

8. The method according to claim 7, which further includes adding the activator to the specified aqueous solution of a carbonate of an alkali metal.

9. The method of claim 8, additionally including the installation of a second absorber of carbon dioxide, United in the operating mode in parallel with the specified absorber of carbon dioxide, where the specified second absorber of carbon dioxide SPO is Aubin accept at least part of the second specified remaining part and enter it into contact with depleted solvent from the obtained at least part of the fourth stream recycling.

10. The method of claim 8, further comprising modifying the internal device specified absorber of carbon dioxide with results in improved mass transfer and a larger number of theoretical plates and improve the recovery of carbon dioxide from the specified at least part of this second allotted part.

11. The method of claim 8, additionally including work specified absorber of carbon dioxide so as to provide a fourth concentration of carbon dioxide less than the specified first concentration of carbon dioxide.

12. The method according to claim 1, where the specified first feedstock reactor contains ethylene and oxygen in addition to carbon dioxide in a concentration and a specified second feedstock reactor contains ethylene and oxygen in addition to carbon dioxide in a certain concentration.

13. Method for producing 1,2-ethanediol or a simple ester of 1,2-ethanediol, including

receipt of ethylene oxide using the method of producing ethylene oxide according to any one of claims 1 to 12 and

the conversion of ethylene oxide to 1,2-ethanediol, or a simple ester of 1,2-ethanediol.