Nanoscale restructuring of aluminium oxide support surface and alkene oxide synthesis catalyst

FIELD: chemistry.

SUBSTANCE: invention relates to a support, a method of preparing said support, a catalyst for epoxidation of olefins having said support and a method of oxidising ethylene to ethylene oxide. The invention describes a support for a catalyst used in epoxidation of olefins which has an inert heat-resistant solid substrate having a surface and several projections coming out of the surface which are detected at scanning frequencies in the interval from approximately 250 cycles/micrometre or more. Described is a method of making such a carrier involving processing the surface of the substrate in order to obtain several projections on the surface of the substrate. The invention describes a catalyst for epoxidation of olefins having the support described above and a catalytically effective amount of silver, and a method of oxidising ethylene to ethylene oxide using the said catalyst.

EFFECT: higher catalyst activity and stability.

21 cl, 2 ex, 6 dwg

The prior art inventions

The technical field to which the invention relates.

The invention relates to a carrier for a catalyst that is useful for epoxydecane olefins. More specifically the invention relates to a carrier and the catalyst, upon receipt of which use media that is useful for the oxidation of ethylene to ethylene oxide. The carrier includes an inert, refractory solid substrate, such as alumina, and has a surface characterized by many nanometer-sized protrusions, protruding above the surface, and comprising a catalytically effective amount of silver.

Description of the prior art,

It is well known that alumina is useful as a base catalyst for epoxidation of olefins. A particularly useful substrate is designed for catalyst comprising silver, which is used in the oxidation of ethylene to ethylene oxide. The substrate material is obtained by firing alumina of high purity in the presence or in the absence of silicon oxide. For this purpose, the substrate material typically includes 90 or more weight percent alumina and from 1 to 6 mass% of silicon oxide. They can be porous or non-porous and have a high or low surface area depending on the purpose for which they are made. The substrate can soda in order to avoid any porous, inert material which does not affect adversely on the catalytic interaction, for which it is used.

According to the method of manufacturing a substrate alumina of high purity, preferably corundum, thoroughly mixed with the auxiliary and main binders. Auxiliary binders are thermally degradable organic compounds having a medium or high molecular weight which, by decomposition, provide the desired porous structure of the substrate. The main binders are inorganic substances on the basis of clay, with a firing temperature lower than those for aluminum oxide and providing mechanical strength of the target substrate. After dry mixing to mass add sufficient amount of water or other solvent, the mass becomes pasty substance. Then pasta conventional means, such as, for example, high-pressure extrusion, granulation or other methods of forming ceramic articles, form particles of the substrate of the catalyst. Then the particles are dried and then calcined at an elevated temperature.

At the stage of burning the auxiliary binder is thermally decomposed to carbon dioxide and water and evaporate, leaving voids in the mass padlock is. These voids are precursors of the porous structure of the target substrate. Then the substrate of the catalyst is cooled, and cooling is the main curing binders, providing the binding of particles to the substrate, and thus, giving the substrate strength and providing the porous structure.

The substrate of the catalyst with the desired characteristics can be easily obtained by using the following method. The pore size distribution of pores and the porosity is easily controlled by selecting a suitable size of the original particles of aluminum oxide, and the particle size, and concentration of the auxiliary and main binders in the mixture. The original particles of aluminum oxide larger size provide greater porosity of the final catalyst. More homogeneous in size particles of aluminum oxide to provide a more uniform porous structure. Similarly the increase in the concentration of auxiliary binders will also lead to an increase in the total porosity of the final catalyst substrate.

U.S. patents describing the production of substrates and aluminum oxide, include U.S. patents 2499675, 2950169 and 3172866. In other patents, such as U.S. patents 3222129, 3223483 and 3226191, presents the active oxides of aluminum. Methods of making highly porous oxides of aluminum RAS is rity in U.S. patent 3804781, 3856708, 3907512 and 3907982. The native oxide of aluminum, having high thermal stability, are disclosed in U.S. patents 3928236. Other, more modern improvements in the manufacture of catalysts carriers are discussed in U.S. patents 3987155, 3997476, 4001144, 4022715, 4039481, 4098874 and 4242233.

It is well known the use of alkali metals and transition metals as promoters for silver catalysts used in the production of ethylene oxide by the incomplete oxidation of ethylene in the gas phase. Such are disclosed in U.S. patents 4010155, 4012425, 4123385, 4066575, 4039561 and 4350616. The promoters used in conjunction with silver located on the substrate surface.

One of the problems of catalysts of the type specified above is that they have insufficient activity and stability under operating conditions. Therefore, it is desirable increase in catalytic activity and stability of catalysts. Unexpectedly, it was found that the modification of the geometrical shape of the surface of the catalyst carrier, through the creation of surface protrusions of nanometer size on the surface of the carrier, achieved significantly improves operational quality of the catalyst. The catalysts are more active and stable when compared to similar catalysts obtained using substrates without such projections.

Brief description of the of the invention

According to the invention features a carrier for a catalyst that is useful for epoxydecane olefins, which comprises an inert refractory solid substrate having a surface and a multitude of protrusions protruding from the surface of the substrate, the protrusions which are present with a frequency in the range from priblisitelno 250 cycles/micrometer or more.

In addition, according to the invention proposes a catalyst useful for epoxydecane olefins, which includes carrier, includes an inert refractory solid substrate, the substrate having a surface and a multitude of protrusions protruding from the surface of the substrate, the protrusions which are detected during the frequency scan interval from priblisitelno 250 cycles/micrometer or more; the carrier comprising a catalytically effective amount of silver.

In addition, according to the invention proposes a method of oxidation of ethylene to ethylene oxide, which involves the oxidation of ethylene with molecular oxygen in the gas phase in a fixed bed, tubular reactor, in the presence of the aforementioned catalyst.

Brief description of drawings

Fig. 1 is an image obtained using an atomic force microscope, the view from above the surface of the carrier A.

Fig. 2 is an image obtained using atomno the power of the microscope, the view from above the surface of the carrier C.

Fig. 3 is an image obtained using an atomic force microscope, the view from above the surface of the carrier C.

Fig. 4 is a micrograph of the surface of the carrier And marked (a) and (D, marked (b), obtained with a scanning electron microscope.

Fig. 5 is an image of the appearance of the catalyst, made on the basis of carriers a, b, C and D.

Fig. 6 is an image of the appearance of the catalyst, made on the basis of carriers E, F and G.

Detailed description of the invention

Upon receipt of the carrier of the invention begins with an inert solid heat-resistant substrate, as is well known to specialists in this field, commercially available. The substrate has a surface, which is treated according to the invention, to obtain many of the projections of nanometer size, protruding above the surface of the substrate.

The substrate used according to this invention, may be selected from a large number of inert, solid, heat-resistant substrates, which may be porous or non-porous. They are relatively inert to the original substances in epoxydecane, products and terms of engagement for its intended use, such as epoxidation olefine is, for example, the oxidation of ethylene to ethylene oxide by oxidation in the gas phase ethylene with molecular oxygen. The substrate may include aluminum oxide, such as alumina, charcoal, pumice, magnesia, Zirconia, titanium dioxide, diatomaceous earth, fallerovo earth, silicon carbide, silicon oxide, silicon carbide, silicon dioxide, clays, artificial zeolites, natural zeolites, ceramic materials and their combination. Preferred carriers are particles of corundum, which is often connected among themselves by means of a bonding agent and have a very high degree of purity, i.e. approximately 95% or more, preferably 98 wt.% or more of corundum. Other components may be other phases of alumina, oxides of silicon, oxides of alkali metals (e.g. sodium oxide) and trace amounts of other metal-containing and/or metal-containing no additives or impurities. Commercially available such a wide range of media. Suitable carrier materials based on aluminum oxide produced in an industrial scale and, basically, they are commercially available in the United Catalysts, Inc., of Louisville, Kentucky and Norton Company, of Akron, Ohio.

Specific types of substrates containing corundum, are particularly preferred. These substrates, including corundum, have a relatively uniform size pore diameters and more the LNO are characterized by the fact that that have a surface area according to BET of from about 0.03 m²/g to about 10 m²/g, preferably from approximately 0.05 m²/g to about 5 m²/g, more preferably from about 0.1 m²/g to about 3 m²/g and pore volume of water from about 0.10 cm³/g to approximately 0.85 cm³/g, preferably from about 0.25 cm³/g to 0.75 cm³/g Average pore diameters for these substrates vary from about 0.5 micrometer to about 50 micrometers. The substrate can have modal, bimodal or multimodal distribution of pore sizes. The surface acidity of the substrate defined by the irreversible adsorption of ammonia at 100°C, often has a value of less than about 2 micromoles per gram of substrate, and often from about 0.05 to about 1.0 micromoles per gram of substrate. Methods of making substrates are described, for example, in U.S. patents 4575494, 3172866, 4356113, 4082697, 4001144, 3856708, 3850849 and 3526602, which are included in the description by reference. Regardless of the nature of the substrate used is usually it is given by the particle shape, lumps, pieces, pellets, rings, spheres, wagon wheels, hollow cylinders with transverse bulkhead and the like, of suitable size for use in reactors with a fixed layer. If desired, part of the s of the substrate can have an equivalent diameter in the range from approximately 3 mm to approximately 10 mm, and preferably in the range from approximately 4 mm to approximately 8 mm, which is typically comparable to the internal diameter of the pipe reactor, in which is placed the catalyst. "Equivalent diameter" is a diameter of a sphere having the same external surface area to volume (i.e. not taking into account the surface within the pores of the particles), as used particles of the substrate.

Basically, a suitable substrate of the catalyst of the present invention can be obtained by mixing the heat-resistant material, such as aluminum oxide, solvent, such as water, auxiliary binder or burnt material, the primary binder and/or agent controlling the porosity. Auxiliary binder or consumable materials include cellulose, substituted cellulose, such as methylcellulose, ethylcellulose and carboximetilzellulozu, stearates, such as the stearates of organic esters, for example, starty methyl or ethyl esters, waxes, granular polyolefins, particularly polyethylene and polypropylene, flour, walnut and the like, which are degradable at temperatures used. They provide the porosity of the substrate material. Consumable material is used primarily to ensure the safety of the porous structure during the initial the basics or phase, not including the firing, in which you can give a mixture of particle shape by molding or extrusion process. Almost all of the amount used during firing, is used to obtain the final substrate. The substrate of the invention preferably is produced by adding a binder material, such as silicon oxide with a compound of an alkali metal, sufficient for almost complete prevention of formation of crystalline compounds of silicon. The main binders include inorganic materials such as clay. The conventional material of the binder, which can be incorporated into particles of aluminum oxide, is a mixture of boehmite, silica Sol stabilized with ammonia, and soluble salts of sodium. The resulting paste is extruded or molded to obtain the desired shape and fired at a temperature of from about 1200°to about 1600°C with the formation of the substrate. When forming the particles by extrusion desirable is to add a common supporting means for the extrusion. The quantity of the component to some extent do not depend on each other and depend on a number of factors, which depend on the equipment used. However, these provisions are in good agreement with the knowledge of a specialist qualified in the field of extras and ceramic materials. Operational quality of the substrate is improved when washing to remove soluble residues.

Then inert solid heat-resistant substrate processed according to the invention for providing the geometrical shape of the surface, with many protrusions, protruding above the surface. The geometric shape of the surface is achieved by processing, effective for partial dissolution of the surface of the substrate and the formation of protrusions of nanometer size by re-allocation of part of the dissolved material on the surface in the form of elements having the form of rods, tubes, fibers or combinations thereof. The protrusions may be formed by maintaining the substrate in a solution of organic acids, inorganic acids, bases, salts or combinations thereof, within a certain period of time and at a temperature sufficient to dissolve a portion of the substrate and the distribution of the dissolved part on the surface of the substrate. A useful treatment is carried out by maintaining the substrate in a solution of alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, or acids such as HNO₃. In one embodiment the treatment is carried out by maintaining the substrate in an aqueous solution of hydroxide of alkali metal or HNO₃at a concentration in the range of from about 0.01 mol to about 10 mo the R, preferably from about 0.05 mol to about 5 mol, and more preferably from about 0.1 mol to about 3 mol. Used the time-keeping range from about 1 minute to about 30 days, preferably from 1 minute to about 5 days, more preferably from 1 minute to about 1 day. Used solution temperature can vary from approximately 0°to approximately 250°C, preferably from approximately 10°to approximately 200°C. and more preferably from approximately 20°to approximately 150°C. After curing, the substrate can be optionally dried by heating at from about 80°to about 500°C., preferably at from about 90°to about 300°C., more preferably at from about 100°to about 200°C. the Curing is possible in static conditions or in conditions of circulation of the solution. If desired, the treatment may include maintaining at the same temperature, usually higher, followed by curing at different temperatures, usually lower. With keeping in the presence of structure-forming reagent in the solution to be processed. Structure-forming reagent may be used to control the size and homogeneous the barb ridges. Suitable, but not the only structure-forming reagents include alkylamines followed, diaminoalkanes, aromatic amines, tetraalkylammonium chloride and halides, cholesterol and polypeptides of natural origin, organic acids and their salts. When using a structure-forming reagent may use solution for treatment with a concentration of from about 0.01 M to about 5 M, preferably from about 0.05 M to about 3 M, and more preferably from about 0.1 M to about 1 M. After incubation, the substrate is washed, for example, water to remove unreacted soluble material and solution for processing and, if desired, dried.

The surface can be characterized by the detection of the projections using AFM (atomic force microscope) or SEM (scanning electron microscope) and/or by measuring the change of the geometrical shape of the surface of the substrate. The protrusions have an average diameter in the range from approximately 1 nm to approximately 100 nm, preferably from about 5 nm to about 50 nm, and more preferably from approximately 10 nm to approximately 30 nm. The protrusions have an average height in the range from approximately 1 nm to approximately 300 nm, more preferably from approximately 5 nm to approximately 200 nm, more is more preferably from approximately 10 nm to approximately 100 nm. It was found that the more active and stable catalysts are obtained when modifying the geometric shape of the surface to ensure,surface, detected during the frequency scan in the range of from about 250 cycles/micrometer or more preferably from about 250 cycles/micrometer up to 800 cycles/micrometer, and more preferably from about 250 cycles/micrometer to 500 cycles/micrometer, characterized by the analysis of the power spectral density for the AFM images of the surface.

To obtain a catalyst for oxidation of ethylene to ethylene oxide carrier, possess the characteristics listed above, then equip a catalytically effective amount of silver. The catalysts obtained by impregnation of the substrate subjected to processing, ions, compounds, complexes and/or salts of silver, dissolved in a suitable solvent, for drawing connections predecessor of silver on the substrate. Then the impregnated carrier is removed from solution and deposited compound of silver is reduced to metallic silver by high temperature calcination. Also preferably applied to the substrate either before or concurrently, or after the application of silver suitable promoters in the form of ions, compounds and/or salts of alkali metals, rastvorennykh in a suitable solvent. Also on the media cause or advance, simultaneously, or after applying silver and/or alkali metals suitable ions, compounds, complexes and/or salts of transition metals, dissolved in a suitable solvent.

The above-described substrate subjected to processing, is impregnated with a solution containing silver intended for impregnation, preferably an aqueous solution of silver. Also at the same time or at separate stages of a substrate impregnated with various catalyst promoters. Obtained according to the invention, the preferred catalysts contain up to 45 wt.% silver, counting on metal, placed on the surface and inside the pores of the porous heat-resistant substrate. The content of silver, counting on the metal, from about 1 to about 40% relative to the total weight of the catalyst, is preferred at the same time, the silver content of from about 8 to about 35% is more preferable. The quantity of silver deposited on a substrate and is present in the substrate, is such a number that represents a catalytically effective amount of silver, i.e. the quantity with minimal cost catalyzes the interaction of ethylene with oxygen to obtain ethylene oxide. Used in the description, the term "catalytically effective amount is in silver" refers to the amount of silver, which provides the measured conversion of ethylene and oxygen to ethylene oxide and selectivity, activity and stability during the lifetime of the catalyst. Useful, but not the only compounds containing silver are oksolat silver, silver nitrate, silver oxide, silver carbonate, silver carboxylate, silver citrate, phthalate, silver, silver lactate, propionate, silver butyrate and silver salts of higher fatty acids and their combinations.

The catalyst includes a catalytically effective amount of silver, a promoting amount of alkali metal, a promoting amount of a transition metal, fixed on the porous heat-resistant substrate. Used in the description, the term "promoting amount" of a particular component of the catalyst refers to the amount at which the component operates effectively to improve one or more of the catalytic properties of this catalyst compared to a catalyst not containing the specified component. Used the exact concentration, of course, will depend, among other factors, the desired silver content, the nature of the substrate, the viscosity of the liquid and the solubility of silver compounds.

In addition to the silver catalyst also contains a promoter alkali metal selected from lithium, sodium, potassium, ubide, cesium or combinations thereof, and cesium is preferred. The amount of alkali metal deposited on a substrate or catalyst or present on the substrate or the catalyst should be promoting. Preferably, the number, counting on the metal will vary from approximately 10 hours per million to about 3000 hours per million, more preferably from about 15 hours/million to approximately 2000 h/m and even more preferably from approximately 20 hours/million to approximately 1500 hours/million, and even more preferably from approximately 50 hours per million to about 1000 hours/million of the total mass of the catalyst.

The catalyst also preferably contains a promoter is a transition metal, which includes the group elements of the periodic table of elements 5b, 6b, 7b and 8 and their combinations. Preferably the transition metal comprises an element selected from the group 7b of the periodic table of elements. Preferred transition metals are rhenium, molybdenum and tungsten, and most preferred are molybdenum and rhenium. The number of transition metal promoter, placed on a substrate or catalyst, or present on the substrate or the catalyst should be promoting. The promoter is a transition metal may be present in an amount of, considering the metal, is about 0.1 micromoles per gram to about 10 micromoles per gram, preferably from about 0.2 micromoles per gram to about 5 micromoles per gram, and more preferably from about 0.5 micromoles per gram to about 4 micromoles per gram of the total weight of the catalyst. In addition, the catalyst may include promoting amount of one or more components containing sulfur, one or more components containing fluorine, or combinations thereof.

The silver solution used for impregnation of the substrate may also include additional solvent or complexing/solubilizers agent, such known in this field. For solubilisation silver in the desired concentration in the environment for impregnation may use a variety of solvents or complexing/solubilizing agents. Useful complexing/solubilizing agents include amines, ammonia, lactic acid and combinations thereof. Amines include alkylenediamine having from 1 to 5 carbon atoms. In one preferred embodiment, the solution includes an aqueous solution of silver oxalate and ethylene diamine. Complexing/solubilizers agent may be present in the solution used for impregnation in the amount of from about 0.1 to about 5.0 moles of Ethylenediamine per mole of silver, preferably from about 0.2 to about 4.0 mol or more is predpochtitelno from about 0.3 to about 3.0 moles of Ethylenediamine per mole of silver.

When using the solvent may be a solvent for water-based or organic-based, and may be polar or partially, or completely non-polar. In General, the solvent should be sufficient solutious ability to solubilisation component of the solution. At the same time, it is preferable to choose a solvent so as to avoid undesirable influences or interactions with solvated by the promoters. Examples of solvents for the organic base include, but are not limited to, alcohols, particularly alkanols, glycols, specifically alkylphenol, ketones, aldehydes, amines, tetragidrofuran, nitrobenzene, nitrotoluene, slimy specifically glyme, diglyme and tetralin and the like. Preferred solvents are organic basis, which have from 1 to about 8 carbon atoms per molecule. You can use a mixture of organic solvents or water and one or more organic solvent, provided that such mixed solvents function as described in the description.

The salt concentration of silver in the solution is in the range from about 0.1 wt.% to the maximum extent possible according to the solubility of the specific applicable combination of salt/solubilizers agent. Basically particularly suitable for use are the two which are solutions of silver salts, containing from 0.5% to about 45 wt.%, preferred concentrations of silver salts from approximately 5 to 30 wt.%.

Impregnation of the selected substrate carry out common methods: impregnation in excess of the solution for impregnation, the impregnated to saturation, etc. Typically, the substrate material is kept in the silver solution until a sufficient amount is not absorbed by the substrate. Preferably the amount of silver solution used for impregnation of the porous substrate, more necessary to fill the pore volume of the substrate. The liquid containing the silver penetrates through absorption, under the action of capillary forces and/or vacuum in the pores of the substrate. You can use a single impregnation or series of impregnations, with or without intermediate drying, partly depending on the salt concentration of silver in solution. Procedures for impregnation are described in U.S. patents 4761394, 4766105, 4908343, 5057481, 5187140, 5102848, 5011807, 5099041 and 5407888, which are included in the description by reference. Possible application of known procedures of the prior application, synchronous application and the subsequent application of different promoters.

Examples of catalytic properties include, in particular, the suitability (robust operation in the operation mode), selectivity, activity, turning ability, stability and productivity. Specialist, qual is fitiavana in this area, it should be clear that one or more individual catalytic properties can be improved in the presence of "promoting amount", at the same time, other catalytic properties can be improved, or can be improved, or can even be weakened. In addition, it is clear that different catalytic properties can be improved under different operating conditions. For example, it is possible to operate the catalyst having improved selectivity for one set of operating conditions, with a different set of conditions under which, instead of improvement in activity is detected improvement in selectivity, and the operator of the plant for production of ethylene oxide can intentionally change the operating conditions to improve specific catalytic properties even at the expense of other catalytic properties to optimize conditions and results, taking into account the cost of maintaining inventory, energy consumption, costs for removal of by-products and the like. The particular combination of compounds containing silver, substrate, alkali metal promoter and promoter transition metal according to the current invention will provide an improvement in one or more catalytic properties compared with the same combination of silver and the substrate and in the absence or in the presence of only one promoter.

the donkey impregnation of the substrate, soaked in connection predecessor of silver and promoters, is subjected to calcination or activate during a period of time sufficient to recover the component of silver to metallic silver and to remove the volatile products of decomposition of the substrate, containing silver. The calcination is conducted by heating the impregnated substrate, preferably with a gradual temperature increase to a temperature in the range of from about 200°C to 600°C, preferably from about 250°C to 500°C and more preferably from about 300°C to 450°C, at pressures of interaction in the range of from 0.5 to 35 bar, over a period of time sufficient to convert the retained silver in metallic silver or decomposition of all or almost all present the organic materials and remove them in the form of a volatile component. In General, when a higher temperature is required for restoration periods. For heat treatment of the impregnated substrate was wide interval periods of heating (for example, in U.S. patent No. 3563914 offered to hold the heat in less than 300 seconds, in U.S. patent No. 3702259 disclosed heating from 2 to 8 hours at a temperature of from 100°C to 375°C for recovery of silver in the composition of the salt in the catalyst, but usually periodontally from 0.5 to 8 hours), it is important that the recovery time correlates with temperature in such a way that is almost a complete transformation of silver salts in a catalytically active metal. For this purpose you can use continuous or stepwise program of heating.

The impregnated substrate is kept in an atmosphere with a combination of inert gas and from about 10 h/m to about 5 vol.% gas that includes oxygen containing oxidizing component. For purposes of this invention, the inert gas is defined as one that, basically, does not interact with the components forming the catalyst at conditions selected to obtain a catalyst. It includes nitrogen, argon, krypton, helium and combinations thereof, and the preferred inert gas is nitrogen. The gas including the oxygen containing oxidizing component may include molecular oxygen, CO₂, NO, NO₂N₂O₃N₂O₄and N₂O₅or substance under conditions of calcination, able to form NO, NO₂N₂O₃N₂O₄or N₂O₅or combinations thereof, and optionally including SO₃, SO₂P₂O₅P₂O₃or combinations thereof. Preferred of these gases is molecular oxygen, and more preferred is a combination Of₂ 2. According to a useful embodiment, the atmosphere comprises from about 10 h/m to about 1 vol.% gas that includes oxygen containing oxidizing component. According to another useful embodiment, the atmosphere comprises from about 50 h/m to about 500 hours/million gas comprising oxygen containing oxidizing component.

The production of ethylene oxide

Basically, the processes of production of ethylene oxide applied on an industrial scale, are continuous interaction of the gas containing oxygen with ethylene in the presence of this catalyst at a temperature in the range of from about 180°to about 330°C., preferably from about 200°to about 325°C., more preferably from about 225°to about 270°C., at a pressure which may vary from about atmospheric pressure to about 30 atmospheres, depending on the mass flow rate and the desired productivity. Basically, use a pressure in the range of from about atmospheric to about 500 lb/in². However, according to the scope of the invention, it is possible to use higher pressures. The time of stay in large scale reactors, mostly are of the order of 0.1-5 seconds. Oxygen can be introduced in collaboration is their flow, containing oxygen, such as air or oxygen from a commercially available source of supply, such as a reservoir. The obtained ethylene oxide is separated and isolated from the products of interaction using conventional methods. However, according to this invention in the process of ethylene oxide is provided by conventional gas recycling, including the recycling of carbon dioxide in normal concentrations, for example, from about 0.5 to 6 percent by volume. The normal process of oxidation of ethylene to ethylene oxide involves the oxidation of ethylene with molecular oxygen in the gas phase in the presence of a catalyst of the invention in a fixed bed in a tubular reactor. Conventional commercially available reactor with a fixed bed ethylene oxide usually in the form of multiple parallel elongated tubes (in a suitable enclosure)filled with catalyst, from about 0.7 to 2.7 inch OD and from 0.5 to 2.5 inch internal Affairs and 15-45 feet in length.

It was shown that the catalysts according to the invention should be particularly selective catalysts for the oxidation of ethylene with molecular oxygen to ethylene oxide. The terms of such oxidation reactions in the presence of a catalyst, according to the present invention, in General, include those described for precede the level of technology. This applies, for example, to suitable temperatures, pressures, times, stay, such substances diluents as nitrogen, carbon dioxide, water vapor, argon, methane or other suitable hydrocarbons, the presence or absence of retarding agents to control the catalytic action, for example, 1,2-dichloroethane, vinyl chloride or chlorinated compounds of polivinil desirable to use recyclo or further transformations in different reactors to increase yield of ethylene oxide and any other special conditions that can be selected for the process of ethylene oxide. Used as a reagent molecular oxygen can be obtained from conventional sources. Suitable for supply of oxygen may represent a relatively pure oxygen, concentrated oxygen flow that includes a large amount of oxygen with lesser amounts of one or more diluents, such as nitrogen, argon, etc. or another oxygen-containing stream such as air. The use of these catalysts in the oxidation of ethylene in no way limited to use in specific conditions, which are known to be effective.

The obtained ethylene oxide is separated and recovered from the reaction products by using common methods, which are known is burnt and used in this area. The use of the silver catalysts of the invention in the production process of ethylene oxide provides in General a higher selectivity for the oxidation of ethylene to ethylene oxide at a given conversion of ethylene than possible with conventional catalysts.

In the production of ethylene oxide mixture supplied reagents may contain from 0.5 to 45% ethylene and from 3 to 15% oxygen, and the remaining part consists of relatively inert materials, including substances such as nitrogen, carbon dioxide, methane, ethane, argon and the like. Preferably the application of the silver catalysts of the invention for obtaining ethylene oxide with the oxygen content in the gas of 95% or more. Usually only a portion of the ethylene interacts in a single pass over the catalyst and after separation of the desired product of ethylene oxide and removal of a suitable purge stream and carbon dioxide to prevent the uncontrolled accumulation of inert substances and/or by-products, unreacted materials are returned to the reactor for oxidation. Only for illustrative purposes, the following terms are frequently used in commercial single reactor for ethylene oxide. SPG - 1500-10000; the inlet pressure is 150 to 400 lb/in²; supply input: ethylene - 1-40%; O₂- 3-12%; CO₂- 2-40%; ethane - 0-3%; argon and/or methane and/or nitrogen: 0,3-0 hours/million chloropyrazole regulator from the total amount of diluent; coolant temperature - 180-315°C; the temperature of the catalyst - 180°C; the degree of conversion of About₂- 10-60%; MA production (working speed) 2-16 lb. MA/cu ft. catalyst/hour.

The following non-limiting examples serve to illustrate the invention.

EXAMPLES

The media And the (comparative)

Used media And (not processed), obtained from the manufacturer. The image of the surface obtained by means of AFM, the carrier shown in Fig. 1. On the surface cannot be detected visually apparent ledges. The analysis of the spectral power density showed no elements at frequencies scan above 200 cycles/micrometer.

Media In (comparative)

Media were obtained by lavage 600 g of carrier And 780 g of circulating water 1.5 M solution of NH₄F. After the interaction between the liquid and the carrier temperature was raised from room temperature to 80°C for 30 minutes, after which the solution was decanted. For washing media used 780 g of deionized water at room temperature, when the circulation within 30 minutes, after which the water was decanted and the carrier was dried at 150°C during the night.

Recorded by visual projections were observed on the AFM image of the surface after treatment of the media, as can be seen in Fig. 2. The spectral analysis is Oh power density showed the presence of elements at frequencies scanning surface below 180 cycles/micrometer.

Media

The media, according to the invention, was obtained by processing 510 g media And 663 g of circulating 0.25 M aqueous solution of NaOH. When interacting NaOH solution with the carrier temperature was raised from room temperature to 80°C for 30 minutes and then maintained this temperature for 1 hour. After processing, the solution was decanted, and for washing media for 1 hour used 663 g of circulating deionized water for rinsing media for 1 hour, after which it was poured. The wash procedure was repeated more than 2 times. Media, processed, dried at 150°C during the night.

At AFM image of the surface can clearly see the bulges to 10 nm in height, as can be seen in Fig. 3. The analysis of the spectral power density showed the presence of elements at frequencies scan more than 200 cycles/micrometer and about 430 cycles/micrometer.

Media D

The carrier D, according to the invention, was obtained by processing 940 g of carrier And 1222 g of circulating 1,25 M aqueous solution of NaOH. When interacting NaOH solution with the carrier temperature was raised from room temperature to 80°C for 30 minutes and then maintained this temperature for 1 hour. After processing, the solution was decanted, and for washing media for 1 hour used 1222 g of circulating Denisova the Noi water, after which it was poured. The wash procedure was repeated more than 4 times. Media, processed, dried at 150°C during the night.

SEM images of the surface before processing and after processing is shown in Fig. 4. The formation of surface protrusions in the form of processed grains obvious.

Media E (comparative)

The media were represented by other media, corundum, from the same manufacturer. Basically, it has the same physical properties as the carrier of A, but has a different chemical composition.

Media F (comparative)

Carrier F was obtained by processing 600 g of the carrier E in the same way as when receiving media Century.

Carrier G

The carrier of G, according to the invention, obtained by placing 510 g of the carrier E in a plastic flask, the flask was evacuated to a pressure below 10 Torr was introduced into the flask 663 g 1 M HNO₃. Once the media becomes filled with liquid, the vacuum was dropped, and the media is filled with HNO_3,kept at room temperature for one hour.

After 1 hour, a solution of HNO₃poured, and to the media for washing was added 663 g of deionized water. The carrier was washed for 30 minutes with periodic shaking of the flask. After 30 minutes the liquid was decanted and at room temperature, was added another portion of deionized water 663 g used for prom is for an hour and then it poured. The last stage was repeated one or more times, after which the carrier is subjected to processing, dried at 150°C during the night.

Receiving catalyst and testing

1. Preparation of the starting solution of silver.

The silver solution was prepared using the following components (in weight parts):

The silver oxide - 834 parts

Oxalic acid - 444 part

The Ethylenediamine - 509 parts

The silver oxide was mixed with water at room temperature, followed by gradual addition of oxalic acid. The mixture was stirred for 15 minutes, and during this period the color black suspension of silver oxide was changed to gray/brown color of silver oxalate. The mixture was filtered and the solid is washed with 3 l of deionized water. The sample was placed in an ice bath and stirred while slowly adding Ethylenediamine and water (in the form of a mixture of 66%/34%) to maintain the reaction temperature below 33°C. After addition of a mixture of Ethylenediamine/water solution was filtered at room temperature. Clear filtrate was used as the initial solution of silver/amine to obtain a catalyst.

2. Receiving catalyst and testing.

A. Adding promoter:

Transparent original silver solution obtained as described above was diluted with a mixture of 66/34 the Ethylenediamine/water. For the catalysis of the Torah, containing a catalytically effective amount of silver and cesium, to the solution was added cesium hydroxide.

b. Impregnation of the catalyst:

From 80 g to 100 g of the sample carrier was placed in a sealed vessel and then subjected to vacuum until the pressure has dropped below 50 mm Hg. 160 ml of finished solution of silver/promoter was introduced into the flask while it was under vacuum. The pressure in the vessel was lowered to atmospheric pressure. Ready to calcination the catalyst was removed from the solution.

C. calcining the catalyst:

The calcination, i.e. the application of silver, induced by heating the catalyst to a temperature of decomposition of silver salts. This was achieved by heating in a furnace, which had multiple zones of heating in a controlled atmosphere. The catalyst was loaded on a moving conveyor belt, which came in a furnace at ambient temperature. The temperature is gradually increased as the catalyst passed from one zone to the next. It was increased to 400°C. at which the catalyst is passed through 4 zone heating. Passing zone heating, conveyor belt entered the cooling zone in which the catalyst is gradually cooled to ambient temperature. The total residence time in the furnace was 42 minutes. The atmosphere in the furnace was controlled, use the Zuya stream of nitrogen in the heating zones.

d. Testing of the catalyst:

Catalyst 2 g was tested in a heated stainless steel tubing. A gas mixture containing 15% ethylene, 7% oxygen and 78% inert substances, mainly nitrogen and carbon dioxide was passed through the catalyst at 3000 lb/in². Temperature interaction was set such that the catalyst was operated under the weight working speed (DIF) = 737.

Silver catalysts promoted with cerium, were obtained on the basis of media A, B, C, D, E, F and G. Catalysts include silver in a catalytically effective concentration. The optimal concentration of cerium was determined experimentally obtaining catalysts with the concentration of cerium, ranging from 400 h/m to more than 600 hours/million Best catalysts were selected according to the test when the weight working speed = 737.

Example 1

In Fig. 5 shows the change in activity and selectivity over time for catalysts obtained on the basis of carriers A, B, C, and D. the Catalysts made on the carriers C and D with the modified geometric shape of the surface, according to the invention, obviously, the more active and stable compared to catalysts made on the basis of media A and B without such surface modifications.

Example 2

In Fig. 6 shows the change in selectionist and activity over time for catalysts, obtained on the basis of carriers E, F and G. Catalysts based media without or following processing is not effective for modifying the surface of the media, as E and F, less stable and less active than catalysts made on the basis of the carrier of G with the surface-modified HNO_3,according to the invention.

Although the invention has been specifically illustrated and described with references to preferred embodiments, professionals, qualified in this field, it must be absolutely clear that it is possible to implement various changes and modifications without departure from the spirit and scope of the invention. It is assumed that the claims be interpreted as describing the disclosed embodiment, the alternatives discussed above and, in addition, all equivalents.

1. A carrier for a catalyst useful for the epoxidation of olefins, which comprises an inert refractory solid substrate, the substrate having a surface and a multitude of protrusions protruding from the surface of the substrate, the protrusions which are detected during the frequency scan in the range of from about 250 cycles/micrometer or more.

2. The carrier according to claim 1, where the substrate includes alumina, charcoal, pumice, magnesia, Zirconia, titanium dioxide, Kizel the Gur, fallerovo earth, silicon carbide, silicon oxide, silicon dioxide, magnesium oxide, clays, artificial zeolites, natural zeolites, ceramic materials, and combinations thereof.

3. Media of claim 1, wherein the protrusions are in the form of rods, tubes, fibers or combinations thereof.

4. Media of claim 1, wherein the protrusions have an average diameter in the range from approximately 1 nm to approximately 100 nm.

5. Media of claim 1, wherein the protrusions have an average height in the range from approximately 1 nm to approximately 300 nm.

6. The carrier according to claim 1, in which the protrusions are detected on the surface of the substrate when the frequency scanning in the range of from about 250 to about 800 cycles/micrometer, the analysis of the power spectral density.

7. The production method of a carrier for a catalyst useful for the epoxidation of olefins, which included a proposal inert refractory solid substrate, the substrate having a surface, and the surface treatment of the substrate to obtain thus many of protrusions protruding from the surface of the substrate, the protrusions which are detected during the frequency scan in the range of from about 250 cycles/micrometer or more.

8. The method according to claim 7, in which the protrusions are in the form of rods, tubes, fibers or combinations thereof.

9. The method according to claim 7, in which the protrusions have an average diameter is between approximately 1 nm to approximately 100 nm.

10. The method according to claim 7, in which the protrusions have an average height in the range from approximately 1 nm to approximately 300 nm.

11. The method according to claim 7, in which the protrusions are detected on the surface of the substrate when the frequency scanning in the range of from about 250 to about 800 cycles/micrometer analysis power spectral density.

12. The method according to claim 7, in which the treatment is carried out by maintaining the substrate in a solution of organic acids, inorganic acids, bases, salts or combinations thereof for a time and at a temperature sufficient to dissolve a portion of the substrate and re-applying the dissolved part on the surface of the substrate.

13. The method according to claim 7, in which the treatment is carried out by maintaining the substrate in a solution of the hydroxide of an alkali metal or HNO₃.

14. The method according to claim 7, in which the treatment is carried out by maintaining the substrate in a solution of the hydroxide of an alkali metal or an NGO₃at a concentration in the range of from about 0.01 mol to about 10 mol.

15. The method according to claim 7, in which the treatment is carried out by maintaining the substrate in a solution of the hydroxide of an alkali metal or an NGO₃at a concentration in the range of from about 0.01 mol to about 10 mol for from about 1 minute to about 30 days at a temperature of from about 0°C. to about 250°C is ri desire, followed by drying.

16. The catalyst useful for the epoxidation of an olefin, which comprises a carrier, which includes inert refractory solid substrate, the substrate having a surface and a multitude of protrusions protruding from the surface, the protrusions which are detected during the frequency scan in the range of from about 250 cycles/micrometer or more; the carrier comprising a catalytically effective amount of silver.

17. The catalyst according to item 16, additionally comprising the promoting amount of a promoter, the promoter comprising one or more compounds containing alkali metal, one or more compounds containing a transition metal, one or more sulfur-containing compounds, one or more compounds containing fluorine or a combination thereof.

18. The catalyst according to item 16, in which the transition metal comprises an element selected from groups 5b, 6b, 7b and 8 of the Periodic system of elements and their combinations.

19. The catalyst according to item 16, in which the transition metal comprises rhenium, molybdenum, tungsten and combinations thereof.

20. The catalyst according to item 16, in which the compound containing the alkali metal includes lithium, sodium, potassium, rubidium, cesium or combinations thereof.

21. The method of oxidation of ethylene to ethylene oxide, which involves the oxidation of ethylene with molecular oxygen in the gas phase in a fixed bed tubular reactor in the presence of the cat is Isadora on P16.