Producing ethylene oxide using fixed concentration of retardant

FIELD: chemistry.

SUBSTANCE: invention relates to versions of a method for controlled oxidation of ethylene to form ethylene oxide, wherein ethylene and oxygen are used along with a silver-based catalyst, a retardant and a co-retardant. When controlling oxidation of ethylene, in order to optimise catalyst properties such as activity and/or selectivity, concentration of the retardant is kept constant within a relatively narrow operating concentration range, and concentration of the co-retardant is varied within a relatively wide operating concentration range. Concentration of the retardant is reduced during the service life of the catalyst.

EFFECT: maintaining efficiency of a silver-based catalyst during oxidation of ethylene as it ages.

16 cl, 3 tbl, 6 ex

BACKGROUND of INVENTION

The SCOPE of the INVENTION

The invention generally relates to process control in chemical reactions. More specifically, the invention relates to an improved process control in chemical reactions oxidation of ethylene.

DESCRIPTION of the PRIOR art

Having industrial importance of chemical reactions, in General, you can do it either in the chemical reactor of periodic action, or in the chemical reactor of continuous operation. In many chemical reactions, with industrial value, as additional substances to the reagents and reaction products include substances that represent: (1) the catalysts that facilitate chemical interaction of a particular reagent, resulting in the formation of a specific product; (2) promoters, which are usually injected into a specific catalyst to stimulate the effectiveness of specific catalyst in relation to a specific chemical reaction (that is, when the efficiency can be optimized, at least in relation to the activity and specificity of the catalyst); and (3) inhibitors, which are intended for insertion into a separate portion of reagents or the flow of reactants to appropriately slow down action is their specific catalyst with respect to a specific chemical reaction.

Along with the fact that there are many chemical reactions that has commercial value that can be used to obtain large quantities (i.e., thousands of tons per year) organic chemical intermediates or products, inorganic chemical intermediates (intermediates or products and mixed organic and inorganic chemical intermediates or products, is particularly important industrially important chemical reaction is the chemical reaction of oxidation (i.e., the chemical reaction of epoxidation) of ethylene with oxygen to form ethylene oxide (i.e., amoxicilina). In turn, the ethylene oxide, which is formed in the preceding reaction, chemical oxidation, can be subjected to hydrolysis with the formation of etilenglikola, which, in addition, contain one significant industrial organic chemical product and/or organic chemical intermediate.

Having industrial value production of ethylene oxide by catalytic reaction of ethylene with molecular oxygen by using a catalyst based on silver in novotrubnom reactor continuous action was well known, productively used and has been continuously improved over many decades. Notwithstanding the above, due to the extraordinary scale of the volume of the MOU in significant industrial production of ethylene oxide, apparently, insignificant otherwise improved method of production, is not yet implemented in the industrial production of ethylene oxide, can, however, still provide significant economic dividends.

Various aspects of the production of ethylene oxide by reaction of ethylene and molecular oxygen in the presence of a catalyst based on silver known in the field of chemical technology. Of particular interest is the use of this method chloride moderator. For example, R. McNamce, USP 2238474, described the addition of ethylene to the supplied raw materials for the oxidation of ethylene to enhance the efficiency of the catalyst.

G. Law, USP 2279469 described that the addition of halogen compounds to the raw material suppresses the formation of carbon dioxide.

G. Sears, USP 2615900 described that the addition of the metal halide to the catalyst on the basis of silver reduces the formation of carbon dioxide.

D. Sacken, USP 2765283 described that the washing medium intended for catalyst receipt of ethylene oxide, chlorine-containing compound, led to higher degrees of conversion and higher output.

Lauritzen, USP 4874879, described preliminary Floridiana fresh Re-containing catalyst prior to the addition of oxygen in the feed raw materials.

M. Nakajima, USP 4831162 described raw materials, which included “chlarotera the second retarder firing and nitric oxide for highly selective catalyst, containing Rb and silver.

So Notermann, USP 4994587 and P. Hayden, USP 5387751, both described gas flow containing chloride inhibitor and nitric oxide for the high selectivity of the catalyst.

P. Shankar, USP 5155242 showed that the preliminary Floridiana fresh catalyst will facilitate the commissioning of a catalyst containing Cs and silver. It was also shown that the preliminary Floridiana allows to introduce Re-containing catalyst at a lower temperature.

P. Hayden, EP 0057066 showed that chlorinated moderators have different efficiency. If the supplied raw material contains several compounds of the moderators on the performance of the catalyst, the effect will be to provide effective, rather than the absolute number of moderators

Y. Oka, USP 6300507, described the addition of chloride of retarder in the form of a liquid, which was injectively in the flow of supply of raw materials.

W. Evans, USP 6372925 and 6717001 showed that during operation of highly selective catalysts, in order to maintain the maximum selectivity, the concentration of retarder should already be optimized. It was also shown that minor changes in the level of the moderator have a distinct impact on the effectiveness of the catalyst.

Finally, P. Chipman, USP 7193094 showed that the operation of the selective catalysis is ora, based on silver, level moderator regulate by changing the reaction temperature.

In addition, in the open press Montrasi and others, in “Oxidation of Ethylene to Ethylene Oxide: Role of Organic Chlorides,” Oxidation Communications, Vol. 3 (3-4), 259-67 (1983)show how the substance is an organic chloride inhibitor that reversibly affects the activity and selectivity of the catalyst based on the silver catalyzed by the catalyst on the basis of silver interaction of ethylene and molecular oxygen leads to the formation of ethylene oxide. By reducing the catalyst activity level of the moderator must be improved. Also in the earlier reference has been shown that the use of the substance, which is the “acceptor chloride”, allows you to use a wider operating range for organic chloride moderator.

Having industrial importance of chemical reactions, such as, in particular, the oxidation of ethylene, undoubtedly, remain extremely important in both domestic and in the global economy. Thus, desirable are methods which can be effectively optimized these important industrial reactions oxidation of ethylene.

The INVENTION

The invention offers a method of optimizing a chemical reaction, in particular, the oxidation of ethylene. The method is applicable, in particular, for ka is alisashamay the chemical reaction of oxidation of ethylene, in which used catalyst based on silver, which shows the effect of aging. The term “aging effect” means that at least one operating parameter of the catalyst based on the silver catalyzed chemical reaction of oxidation of ethylene deteriorates depending on the time of use of the catalyst based on silver. The operating parameters may include, among others, the activity of the catalyst on the basis of silver and selectivity of the catalyst based on silver. In the chemical reaction of oxidation of ethylene using a gas mixture of reagents, which contains the moderator, which affects the performance of the catalyst based on silver in the chemical reaction of oxidation of ethylene, and co-moderator, which affects the catalyst on the basis of silver and moderator in the reaction of the chemical oxidation of ethylene. In the invention does not assume that a co-moderator to a certain extent affects the catalyst on the basis of silver (i.e., usually in the context of catalyst selectivity on the basis of silver and/or activity of the catalyst based on silver) in the absence of the moderator.

The invention brings special favor when operating concentration range co-moderator wider operational range of concentrations of the inhibitor. Under these conditions, the concentration of the inhibitor to ora effective in a more narrow range of concentrations, can be maintained constant, while the concentration co-moderator, which is effective in a wider working range of concentrations can be varied to optimize (either continuously or discretely) the chemical reaction of oxidation of ethylene, when the catalyst on the basis of silver, showing the effect of aging, aging. The invention has value, since effective regulation of the concentration of inhibitor which is effective over a wide operating range of concentrations typically occur less difficult to manage an effective chemical process than with the regulation of the concentration of the inhibitor that is effective in a narrower operating range of concentrations.

A specific method for the controlled oxidation of ethylene involves reacting ethylene with oxygen in the presence of a catalyst based on silver, moderator and co-moderator c the formation of ethylene oxide. This particular method also includes maintaining the concentration of the inhibitor constant, but varying the concentration of the co-moderator during aging of the catalyst based on silver.

Another specific method of the controlled oxidation of ethylene involves reacting ethylene with oxygen in the presence of a catalyst based on silver, which contains rhenium about otor, moderator and co-moderator, with the formation of ethylene oxide. This other particular method also includes maintaining a constant concentration of the inhibitor, but varying the concentration of the co-moderator during aging of the catalyst based on silver.

Another specific method of the controlled oxidation of ethylene involves the interaction of ethylene with oxygen in the presence of a catalyst based on silver, organic halide moderator and organic dehalogenating co-moderator, with the formation of ethylene oxide. This other particular method also includes maintaining a constant concentration of organic halide moderator, but varying the concentration of organic dehalogenating co-moderator during aging of the catalyst based on silver.

The invention also provide an effective way of maintaining performance of the catalyst at their maximum level. It was found that when the catalyst efficiency optimize by adjusting the concentration of the inhibitor, then the output of the catalyst to a new level requires a longer period of time, which is 10-24 hours. In contrast and unexpectedly, in the framework of the present invention, when the catalyst efficiency optimize by adjusting the concentration of the emission co-moderator, the output of the catalyst to a new level requires a limited period of time, which is 4-8 hours.

DESCRIPTION of the PREFERRED VARIANT of the INVENTION, the

The invention includes a method of optimizing the chemical reaction of oxidation of ethylene understandable in the context of the following description. A separate variant implementation of the invention within the following description is applicable in conditions where the chemical reagent is ethylene in the presence of a catalyst based on silver is subjected to interaction with the formation of the chemical product of ethylene oxide, where the chemical reaction of oxidation of ethylene to compensate for the effect of aging can be slowed through the use of: (1) moderator, which has activity against the catalyst; and (2) co-moderator, which has activity in relation to the catalyst, and in relation to the moderator.

Typically, in the method for industrial production of ethylene oxide provide continuous communication within the reactor oxygen-containing gas oxidant with ethylene in the presence of a catalyst based on silver, with the temperature being in the range from about 180°to about 330°C, more preferably from about 200°C to about 325°C, and most preferably from about 210°C to approximately 270°C. the pressure in the reactor may vary approximately from atmospheric pressure to about 30 atmospheres, depending on the desired mass flow rate and performance (i.e., volume). However, within any of the several embodiments of the invention can be used in higher pressure inside the reactor.

The supplied gas mixture for the oxidation of ethylene may contain about 0.5 to about 45% (by volume) of ethylene, from about 3 to 15% (volume) oxygen, and up to about 8% (by volume) of carbon dioxide. The oxygen level in the feed should not exceed a threshold level of Flammability, which will be determined by the level of hydrocarbons in the feed. The equilibrium of the supplied gas mixture may contain relatively inert substances, including, among others, nitrogen, methane, argon and the like. Usually, only a portion of gaseous ethylene reactant and gaseous oxygen oxidant interact with the passage inside the reactor above the catalyst based on silver, when gaseous ethylene reactant and gaseous oxygen oxidizer interact with the formation of ethylene oxide. After the separation of ethylene oxide, the desired product of chemical reactions, and removal of unwanted inert ha is s and gaseous by-products, unreacted gaseous ethylene reagent and unreacted gaseous oxygen oxidizer sent for recycling to the reactor.

Within the context of the description above, the present variant embodiment of the invention most often turn to the use of a moderator (that is, as a rule, gas)and co-moderator (that is, as a rule, gas) catalyzed by the catalyst on the basis of silver reaction of ethylene and oxygen, leading to the formation of ethylene oxide. Also to this variant embodiment of the invention relates to the interaction of substances moderator and matter co-moderator with a catalyst based on silver. Thus, followed by further discussion of the substance of the catalyst based on silver, substances moderator and matter co-moderator.

As seen in the context of the description above, the catalyst in the oxidation of ethylene is usually a catalyst based on silver, mounted on a ceramic carrier. Ceramic media containing alumina are particularly prevalent. It is not excluded other ceramic substrates used as an alternative or as an additive, although usually they are less common. The surface area of suitable ceramic substrates ordinary which will be from, approximately 0.3 to approximately a 2.0 square meters per gram, and the value of hygroscopicity will be, approximately, from 0.30 to about 0.60 ml per gram.

Ceramic catalyst carrier on the basis of silver contains a catalytically effective amount of silver, localized thereon and/or therein. Such catalysts based on silver get soaking the ceramic carrier, at least one precursor of silver, such as silver ion, a compound of silver, set of silver or silver salt, or, alternatively, a mixture dissolved in a suitable solvent, suitable to facilitate impregnation of at least one precursor of silver inner part or surface of the ceramic carrier. Such ceramic carrier impregnated substance is a precursor to silver, then remove from the solution of the precursor of silver. And, at least one caused the predecessor of the silver is converted into metallic silver, usually, but not exclusively, by firing at high temperature. Also preferably, the presence of deposition on the ceramic carrier before, together or after impregnation of at least one substance is a precursor of silver, at least one precursor of a promoter, which is an alkaline metal, in the form, at the ore, one ion of an alkali metal, compound or salt dissolved in a suitable solvent. Also preferably, the deposition on the ceramic carrier before, together or after impregnation of at least one precursor of silver, and/or at least one precursor of a promoter, which is an alkaline metal, at least one suitable precursor of the promoter, which is a transition metal, in the form of ion, compound, complex and/or salt, the precursor of the transition metal promoter, which is also dissolved in a suitable solvent.

Typically, the ceramic carrier is impregnated with the impregnating solution of the substance, a predecessor of silver, which preferably is an aqueous solution of silver ions. Ceramic media can also be impregnated simultaneously or at separate stages of a substance is a precursor of the promoter, which is an alkaline metal, and a substance is a precursor of the promoter, which is the transition metal, as discussed above. Catalysts based on silver, obtained and used in accordance with this embodiment of the invention usually contain up to about 45 wt.% silver, presented in the form of metal deposited on the surface and through all the pores of the ceramic carrier. The content of silver in the form of metal is one silver, which is from about 1 to about 40 wt.% from the total mass of the catalyst, is preferred. More preferably, the silver content of approximately 8 to approximately 35%. Applicable substances predecessor of silver, in particular, include, among others, silver oxalate, silver nitrate, silver oxide, silver carbonate, silver carboxylate, silver citrate, phthalate, silver, silver lactate, propionate, silver butyrate and silver salts of higher fatty acids of silver, and combinations thereof.

In accordance with the above description, the amount of silver deposited on a ceramic carrier or present on the ceramic carrier, is a quantity that is defined as “a catalytically effective amount of silver” (i.e., the number, which is economical catalyzes, for example, the reaction of ethylene and oxygen, leading to the obtaining of ethylene oxide). Used in the present description, the term “catalytically effective amount of silver” refers to the amount of silver, which with a stable activity and stable selectivity during the lifetime of the catalyst gives a significant transformation, for example, ethylene and oxygen to ethylene oxide.

As described above, adding to the catalytically effective amount of silver is, the catalyst on the basis of silver, according to the variant embodiment of the invention, also includes a promoting amount of a promoter, which represents an alkali metal and a promoting amount of a promoter, which represents a transition metal, each of which is also printed on the ceramic carrier. Used herein, the term “promoting amount” of a promoter, which represents an alkali metal or a transition metal, refers to the amount of such a component promoter that functions efficiently, ensuring the improvement of one or more catalytic properties of the catalyst based on silver, when compared with a catalyst based on silver, not containing component-specific promoter. The exact concentration of a specific promoter will depend, among other factors, the required content of silver in the catalyst based on silver, the nature of the catalyst carrier based on silver, the viscosity of the impregnating solution and the solubility of the particular predecessor of silver.

The solution of the precursor and the precursor of the promoter used for impregnation of the ceramic carrier may also contain an optional solvent or complexing/solubilizers agent known in the art. A wide variety dissolve the oil or complexing/solubilizing agents can be used, to make soluble to the desired concentration of the substance predecessor of silver in the impregnating solution. Applicable complexing/solubilizing agents include amines, ammonia or lactic acid. Amines include alkylenediamine and alkanolamine having from 1 to 5 carbon atoms. In one embodiment of the invention, specific impregnating solution comprises an aqueous solution of silver oxalate (i.e., as predecessor of silver) and Ethylenediamine. In General, the complexing/solubilizers agent may be present in the impregnating solution in an amount of from about 0.1 to about 5.0 moles of Ethylenediamine per mole of the precursor of silver, preferably from approximately 0.2 to approximately 4.0 mol, and more preferably, from about 0.3 to about 3.0 moles of Ethylenediamine per mole of precursor silver. The concentration of the precursor of silver (such as silver salt in the impregnating solution is in the range from about 1 wt.% to the maximum concentration allowed by the solubility of the used combination of the specific precursor silver/solubilizers agent. Usually it is acceptable to use the solutions of a substance, a predecessor of silver containing from about 7%to approximately 45 wt.% silver. The preferred concentration of silver ranges from about 10% to about 35 wt.%.

Impregnation of concrete ceramic media usually carry an accepted way, soaking the excess amount of the solution when the initial moisture content, and so on. Typically, the ceramic carrier is dipped in a solution of a substance predecessor of silver, up until a sufficient quantity of a solution of a precursor of silver is absorbed into the ceramic media. Preferably, when the number of solution of the precursor of the silver used for impregnation of the carrier does not exceed the number required to fill the pore volume of the carrier. The solution of the substance, a predecessor of silver and/or solution of a substance, precursor of the promoter penetrates into the pores of the ceramic media with absorption, capillary forces and/or vacuum. A single treatment or a series of impregnations can be used. They can combine or not to combine with intermediate drying, in part, depending on the concentration of the precursor of silver and/or the precursor of the promoter in the impregnating solution. Mainly you can use the well-known pre-procedure pre-precipitation, coprecipitation and post-deposition of different promoters to get the required to naliticheskie catalysts based on silver.

In particular, the standard catalyst, which contains only the silver, and cesium, obtained according to example 5 in U.S. patent (USP) 4012425. Highly selective catalyst, which also contains the Re as a promoter, was obtained according to examples 5-10 U.S. patent (USP) 4766105.

Examples of catalytic properties of the catalyst on the basis of silver include, among others, ease of use (resistance to being out of control), selectivity, activity, conversion rates, and stability. As is obvious to a person skilled in the art with the help of “promoting amount” of the promoter of one or more of the individual catalytic properties can be enhanced, while other catalytic properties may or may not be reinforced, or can even be weakened. In addition, it is clear that in different operating conditions can be reinforced with different catalytic properties. For example, a catalyst having improved selectivity for one set of conditions for chemical reactions that can be continuously optimized in accordance with the current embodiment of the invention, other conditions may be adjusted in such a way that caused the improvement carried out in relation to the activity, not selectivity. In this respect, the specific conditions of functioning the tion, inherent in the system mode of a chemical reactor such as a chemical reactor for the oxidation of ethylene, can be modified in order to take advantage of some catalytic properties, even at the expense of other catalytic properties. When this optimization conditions and results, you can take into account the cost of raw materials, energy costs, cost of removal of by-products and the like.

After impregnation, the ceramic carrier impregnated substance is a precursor of silver and substance(s)precursor(s) promoter(s), calcined (or otherwise activate alternative as appropriate) in sufficient time for the conversion of the substance, the predecessor of the silver in metallic silver and substances predecessors promoters promoters, and remove solvent and volatile products of decomposition of the resulting catalyst based on silver. In particular, the finish annealing by heating the impregnated microporous media, gradually increasing the speed of heating, preferably to a temperature in the range from approximately 200°C to about 600°C, preferably from about 220°C. to approximately 500°C; and more preferably, from approximately 240°C to about 450°C; Rea the operating pressure, in the range from 0.5 to 35 bar for a time sufficient to convert that saturates the media predecessor of silver in metallic silver and predecessors promoters promoters, and decomposition of all or essentially all present the organic substances and removing them in the form of volatile substances. In General, higher temperature calcination provide shorter time periods of annealing. Periods of time of annealing, comprising from about 10 minutes to about 24 hours are common.

In the current version of the invention, the substance moderator typically includes, among others, organic chlorides, such as, among others, the chlorine-methanes, haratani, chloropropane and other chloralkali and chloralkali, such as vinylchloride and chloropropene. It is not excluded other organic chlorides, and other organic halides. In particular, suppose that the substance of the retarder includes an effective amount of all organic chloride (or alternatively, an organic halide) parts, which are supplied in the gas mixture. The amount of organic chloride parts in the feed gas mixture is typically in the range from 0.5 to 50 parts by volume per million. At the beginning of the service life of the catalyst on the basis of sør the wall, the concentration of organic chloride is typically in the range from approximately 0.5 to approximately 5 parts per million. Agreed that this concentration will often adjust to higher concentrations, as aging during its lifetime, the catalyst based on silver. Often in a continuous way is difficult to precise regulation of the range of concentrations of the inhibitor, expressed in parts per million.

Under this variant of the invention, the substance is co-moderator typically includes, among others, organic matter, non-halide, such as organic gas that does not contain chlorides, such as, among others, ethane, propane and/or butane, or alternative related alkanes. Such organic negligently and achlorhydria substances co-moderators are usually present in the range from about 0.1 to about 10 volume percent relative to the amount of other supplied gas, which is supplied in the gas mixture.

As is clear to a person skilled in the technical field, when deposited on the carrier of the catalyst based on silver ages, it loses its activity. Thus, when high-temperature reactions will, as a rule, it is necessary (in particular, for highly selective rolled atora based on silver, besieged by the media and promoted with rhenium, compared to less selective deposited on the carrier of the catalyst based on silver, in which there is no rhenium) to support the activity and performance of the catalyst on the basis of silver during its aging. Therefore, with the increase of reaction temperature will also need to increase the concentration of gaseous moderator to maintain a constant and optimum efficiency of the catalyst based on silver.

In the current embodiment of the invention and the invention proceed from the fact that the more rational is the preservation of a fixed concentration of a substance moderator throughout the lifetime of the catalyst based on silver. Most often, within the context of a variant embodiment of the invention and of the invention, this particular concentration will be equal to or will exceed the highest concentration of a substance - moderator, intended for a specific catalyst based on silver.

For example, the effective concentration of combined chlorine-containing hydrocarbon moderators for fresh catalyst based on silver, which contains silver and cesium and rhenium as a promoter, is typically in the range from about 0.5 to about 5 parts per million. Nai is " new " concentration of the inhibitor throughout the lifetime deposited on the catalyst carrier on the basis of silver could be, approximately 5 to approximately 20 parts per million. In the current embodiment of the invention, throughout the lifetime of the catalyst based on silver use this higher concentration as a constant concentration. Within the current variant implementation of the invention involve the use of substances co-moderator as an auxiliary component in the feed gas mixture. When, as a result of aging, the capacity of the specific catalyst on the basis of silver decreases, in the current embodiment of the invention provide for re-enhancing substances co-moderator to maintain optimum efficiency of the catalyst based on silver.

Essentially, according to the present invention, at the beginning of the service life of the catalyst based on silver, the relatively high concentration of organic halide moderator, such as an organic chloride is sufficient to reduce the activity of the catalyst on the basis of silver to an undesirable level. However, the controlled addition of organic dehalogenating substances co-moderator is able to restore the optimal efficiency of the catalyst based on silver. At this stage of the service life of the catalyst based on silver, concentration and moderator, and will slow down the La are at their maximum values. Within the context of the current alternative embodiment of the invention and of the invention, when the catalyst on the basis of silver is aging, the concentration of inhibitor in the feed gas mixture do not change, but the concentration of a substance co-moderator gradually adjust to preserve and maintain the optimum efficiency of the catalyst based on silver.

As described above, co-moderator, preferably, is an organic negligently (i.e., not chloride) substance, such as, among others, ethane or propane. When the appropriate concentration of a substance co-moderator include in the feed gas mixture, the catalyst based on silver acquires a higher activity and a higher selectivity. When the catalyst on the basis of silver ages, its efficiency is deteriorating and will need to gradually reduce the concentration of a substance co-moderator. This is a controlled reduction of the concentration of a substance co-moderator is intended to restore optimum efficiency of the catalyst based on silver, in particular, in relation to the activity of the catalyst on the basis of silver, despite the fact that the catalyst based on silver is the selective catalyst based on silver.

As background information, the term “selectivity” of the catalyst on the basis of silver sublattice which implies a share of the reagent (i.e., ethylene), which is converted into a product in a specific chemical reaction.

Selectivity(%)=

Mol of ethylene converted to ethylene oxide× 100

the number of moles of reacted ethylene

In accordance with the embodiment of the invention and the invention range used in the concentration of a substance co-moderator is usually larger than the range used in the concentration of the substance-moderator. This greater range used in the concentration of a substance co-moderator is usually easy to control, and its size is usually also allows minor variations. For example, in this embodiment of the invention the fresh catalyst on the basis of silver may have a peak efficiency at a concentration of organic halide (i.e., chloride) gaseous moderator in the range from approximately 0.5 to approximately 5 ppm and the concentration of alkangovolo dehalogenating (i.e., nejarenogo) organic matter co-moderator in the range from approximately 0.1 to approximately 5% of the feed material gas mixture. In accordance with the current embodiment of the invention, at the end of the service life of the catalyst based on silver, the concentration of the organic halide gas retarder remains unchanged, but the con is entrace organic dehalogenating gaseous co-moderator can usually be in the range of concentrations from approximately 0.01 to approximately 1.0 percent.

As a more specific variant of the invention according to this invention, at the start of the oxidation reaction of ethylene with fresh catalyst based on silver, supplied material gas mixture at a lower temperature than the normal operating temperature (i.e., 120-200°C) add organic halide gas retarder. At this relatively low temperature, fresh catalyst based on silver will show no activity or reduced activity, depending on the composition of the feed material gas mixture. From the outset, the concentration of the inhibitor in the feed material gas mixture is brought to a constant level, which will be used throughout the lifetime of the catalyst based on silver. Simultaneously, the feed material gas mixture are selected so as to contain the maximum level of a substance co-moderator. When the aging of the catalyst based on silver, the efficiency of the catalyst based on silver optimize by continuous adjustment of the concentration of a substance co-moderator.

In yet another more specific embodiment of the invention, when starting a fresh catalyst on the basis of the supplied silver to mate ialu gas mixture also add organic halide vapor retarder at a lower temperature, than the normal operating temperature (i.e., 120-200°C). At this relatively low temperature, the catalyst on the basis of silver will exhibit reduced activity, depending on the specific feed material gas mixture. Since specific chemical reaction the concentration of the inhibitor in the feed material gas mixture is brought to a constant level, which will be used throughout the lifetime of the catalyst based on silver.

At this early stage in specific chemical reactions it is not necessary to add substances co-moderator. Rather, the substance co-moderator will be added when it becomes apparent that the concentration of retarder has a permanent impact on the catalyst based on silver. The detailed composition of the outgoing gas can be used to determine when this is achieved the specific condition; and at this stage, the substance co-moderator will be added to the supplied material gas mixture. Alternatively, the activity of the catalyst on the basis of silver (i.e., performance) can be used to determine if the balance of the substance of the inhibitor in the feed material gas mixture deposited on the surface of the carrier catalyst on the basis of silver. During the initial phases of the service life of the catalyst based on silver, with increased concentration of the substance - moderator, in use, the catalyst based on silver, as a rule, will have essentially reduced the activity.

When you add a substance co-moderator, the activity of the catalyst on the basis of silver increases, and, for example, effectively initiated the expected oxidation reaction of the olefin. At this stage the concentration of a substance co-moderator in the feed material gas mixture should be increased in order to achieve optimum efficiency of the catalyst based on silver and on the selectivity and activity. Optimal performance should be obvious, when further increase of the concentration of substances co-moderator leads to a drop in selectivity of the catalyst based on silver. This optimal level of substances co-moderator will be a higher level, which I would use for adjusting of activity of the catalyst based on silver.

Over the lifetime of the catalyst based on silver, the efficiency of the catalyst decreases, and usually will require increased the reaction temperature to maintain the performance of the catalyst based on silver. With this increase in the reaction temperature will usually be necessary adjustment of substances co-moderator, to restore optimalnoe efficiency deposited on the catalyst carrier based on silver. When the catalyst continues to age and after several reductions in the concentrations of substances co-moderator, subsequent optimal performance will be lower than the initial optimal efficiency of the catalyst based on silver had in early life. As a result, will receive a lower catalyst activity and/or lower the selectivity of the catalyst. At the end of the service life of the catalyst based on silver, the concentration of a substance co-moderator will be particularly low, and the efficiency of the catalyst will be reduced to the level at which, on the basis of economic considerations, it is necessary to replace the catalyst.

EXAMPLES

Examples 1-3

Upon receipt and activation of the catalyst on the basis of silver, as a rule, followed the conventional techniques described above. Before soaking 150 g portion of the carrier of aluminum oxide was placed in A flask and was pumped up to approximately (ca.), 0.1 Torr. The above-described silver solution were added aqueous solutions of cesium hydroxide, perrenial acid and ammonium sulfate, to obtain a catalyst composition in accordance with examples 5-10 U.S. patent 4766105. The wet calcination of the catalyst was carried out in the kiln, equipped with a belt conveyor. In this unit the wet catalyst is moved on the conveyor belt, done the frame stainless steel through the multi-zone furnace. All zones of the furnace continuously purge the pre-heated nitrogen, ultra high purity, and the temperature is gradually increased when the catalyst comes from one zone to the next. The heat comes from the furnace walls and from the pre-heated nitrogen.

In this example 1, the wet catalyst was done in a furnace at ambient temperature. Then the temperature is gradually increased to the maximum temperature, which constitutes approximately 450°C, when the catalyst is passed through the heated zone. In the last (cooling) zone, the temperature is now activated catalyst was rapidly lowered to a temperature lower 100°C, prior to its release into the surrounding atmosphere. The total residence time in the furnace was approximately 45 minutes.

The catalyst on the basis of silver loaded 32.5 mm reactor tube and tested using the supplied gas mixture, which included the following components:

25% ethylene;

7% oxygen;

1% carbon dioxide;

3 parts per million, ethylchloride (moderator); and

0.25% ethane (co-moderator).

The flow rate of the supplied gas mixture is regulated so as to obtain the spatial velocity of the gas component 3200 hours¹. The temperature of the reactor is optimized so that to get the performance (output), with the bringing of 220 kg of the resulting ethylene oxide per cubic meter of catalyst on the basis of silver per hour. The supplied gas mixture is modified to obtain optimal selectivity by changing the concentration or moderator or co-moderator. Measured operating parameters are given in table 1.

The results in table show that optimal conditions can be achieved in a shorter time, if you change the concentration of a substance co-moderator.

Examples 4-5

A similar catalyst on the basis of silver and similar methods used in examples 1-3, were re-used, except that the purpose of the modification of the composition of the gas mixture supplied was to optimize the reaction temperature. The results are shown in table 2.

Examples 4 and 5 illustrate that at a constant concentration of the inhibitor, the reduction of the concentration co-moderator can lead to a more efficient reaction at lower temperatures with minimal loss in selectivity.

Example 6

Again using the catalyst on the basis of silver, similar to the catalyst used in the preceding examples. In this example, the concentration of a substance co-moderator for a long time continuously reduced in order to maintain optimum efficiency of the catalyst based on silver, while the concentration of inhibitor was constant. The results are illustrated in table 3.

The results in table 3 clearly show that the concentration of inhibitor in the oxidation of ethylene can be maintained constant, a is the concentration of a substance co-moderator can be reduced when the catalyst based on silver in the oxidation of ethylene is aging, to maintain the efficiency of the catalyst based on silver in the oxidation of ethylene.

The preferred embodiment of the invention and the examples according to the invention serve to illustrate the invention and do not limit the invention. Fixes and modifications can be made in respect of processes, substances, devices, and volumes, in accordance with the preferred embodiment of the invention and the examples according to the invention, provided that the implementation of the invention and the examples according to the invention, moreover, are in accordance with the accompanying claims.

1. The way the controlled oxidation of ethylene, including:
the interaction of ethylene with oxygen in the presence rolled atora based on silver, moderator and co-moderator, leading to the formation of ethylene oxide; and
maintaining a constant concentration of the inhibitor, with a gradual decrease in the concentration of the co-moderator during the lifetime of the catalyst based on silver.

2. The method according to claim 1, in which the catalyst on the basis of silver exposed to the effect of aging that affects the activity of the catalyst based on silver.

3. The method according to claim 1, in which the catalyst on the basis of silver exposed to the effect of aging that affects the selectivity of the catalyst based on silver.

4. The method according to claim 1, in which the catalyst is based includes silver deposited on the carrier of the catalyst based on silver.

5. The method according to claim 1, in which the catalyst based on silver includes at least one promoter.

6. The method according to claim 1, in which the catalyst on the basis of silver contains rhenium.

7. The method according to claim 1, wherein the retarder comprises an organic halide.

8. The way the controlled oxidation of ethylene, including:
the interaction of ethylene with oxygen in the presence of a catalyst based on silver, which contains rhenium promoter, moderator and co-moderator, with the formation of ethylene oxide; and maintaining a constant concentration of the inhibitor, with a gradual decrease in the concentration of the co-moderator during the lifetime of the catalyst on the again of silver.

9. The method according to claim 1 or 8, in which:
the retarder is active with respect to the catalyst on the basis of silver in the first range of concentrations; and co-moderator is active with respect to the catalyst on the basis of silver and moderated in the second range of concentrations greater than the first concentration range.

10. The method according to claim 1 or 8, in which the retarder includes organic matter, which is not a halide.

11. The method according to claim 10, in which the specified organic negligence substance is or ethane, or propane, or butane.

12. The method according to claim 11, in which the specified organic negligence substance is ethane.

13. The way the controlled oxidation of ethylene, including:
interaction of ethylene and oxygen in the presence of a catalyst based on silver, organic halide moderator and organic dehalogenating co-moderator, with the formation of ethylene oxide; and maintaining a constant concentration of organic halide moderator, with a gradual decrease in the concentration of organic dehalogenating co-moderator during the lifetime of the catalyst based on silver.

14. The method according to item 13, in which the catalyst on the basis of silver contains rhenium promoter.

15. The method according to item 13, in which:
organic halide moderator JW is AESA active with respect to the catalyst on the basis of silver in the first range of concentrations; and
organic negligently co-moderator is active with respect to the catalyst on the basis of silver, and to the organic halide to the moderator in the second range of concentrations greater than the first concentration range.

16. The method according to item 13, in which the specified organic negligence substance is one of ethane, propane and butane.