Alkylene oxide catalyst that can be produced quickly in one step

Abstract

A supported silver catalyst and its use in a process for producing an olefin oxide, such as ethylene oxide, by direct oxidation of an alkylene with oxygen or an oxygen-containing gas, wherein the catalyst provides good catalytic activity and / or efficiency despite silver loading levels in the range of 16-25%.

Description

[Technical field]

[0001] This invention relates to a supported silver catalyst, its preparation and its use in the production of alkylene oxides, particularly ethylene oxide, directly from oxygen and olefins such as ethylene. [Background technology]

[0002] Alkylene oxides are known for a variety of uses. For example, ethylene oxide is used to produce ethylene glycol, which is used in preparing polyester fibers and resins, nonionic surfactants, glycol ethers, ethanolamines, and polyethylene polyether polyols. Propylene oxide is used to produce propylene glycol and polypropylene polyether polyols, which are used in polyurethane polymer applications.

[0003] The production of ethylene oxide by the direct reaction of ethylene with oxygen or an oxygen-containing gas in the presence of a silver catalyst is an old and well-developed technology. A summary of the history of direct ethylene oxidation can be found in U.S. Patent No. 4,916,243. This patent more specifically describes a catalyst comprising silver deposited on an alumina macroporous support and further comprising cesium and at least one other alkali metal selected from the group consisting of lithium, sodium, potassium, and rubidium, such that the combination of cesium and the other alkali metal exhibits a synergistic promotion effect on the oxidation process.

[0004] Supported silver catalysts for alkylene oxide production should have acceptable activity, efficiency, and stability. The "activity" of a catalyst can be quantified in a number of ways, including the mole percent of alkylene oxide contained in the reactor outlet stream relative to the alkylene oxide in the inlet stream while the reactor temperature is maintained substantially constant (the mole percent of alkylene oxide in the inlet stream typically approaches zero percent, but not necessarily), and the temperature required to maintain a given alkylene oxide production rate. Often, activity is measured over a period of time in terms of the mole percent of alkylene oxide produced at a particular constant temperature. Alternatively, activity can be measured as a function of the temperature required to maintain a particular constant mole percent production of alkylene oxide, such as ethylene oxide. The "efficiency" of oxidation, which is synonymous with "selectivity," refers to the total amount, in mole percent, of olefins converted or reacted to form a particular product. For example, "selectivity to alkylene oxide" refers to the mole percent of olefins converted or reacted to form alkylene oxide. One measure of a catalyst's pot life is the length of time that reactants can pass through a reaction system during which acceptable productivity is obtained, taking into account all relevant factors. "Deactivation," as used herein, refers to a permanent loss of activity and / or efficiency, i.e., a decrease in activity and / or efficiency that cannot be restored. In general, deactivation tends to proceed more quickly when higher reactor temperatures are used. The "stability" of a catalyst is inversely proportional to the deactivation rate. A lower deactivation rate is generally desirable.

[0005] Recently, improvements in the activity, efficiency, and stability of alkylene oxide catalysts have been achieved by the use of modified alumina supports prepared from high purity alpha-alumina, preferably with a compositional purity of greater than 95 weight percent. For example, WO 2005 / 023417(A1) discloses the modification of high purity preformed alpha-alumina supports by impregnating the support with an alkali metal hydroxide, such as sodium hydroxide, and then washing the support to remove unbound or excess alkali. The modified support is then impregnated with additional promoters, such as silver and cesium, and optionally rhenium, manganese, and / or other alkali metals. Similarly, WO 2005 / 039757(A1) discloses the modification of high purity alpha-alumina supports with zirconium silicate (zircon), and then the zircon modified alumina is impregnated with silver and one or more promoting cations or anions. The supports and catalysts derived from these modification processes typically do not contain binders, such as clay. Avoidance of binders is desirable since they tend to introduce undesirable amounts of extraneous metals.

[0006] Other references such as WO 2007 / 123932(A1) describe highly efficient catalysts that are modified for better performance in the event of reactor upset.

[0007] These reported catalysts typically rely on relatively high loadings of silver, typically greater than 30 weight percent, or even greater than 35 weight percent. To achieve such high levels of silver, the manufacturing process typically requires multiple impregnation steps, increasing the cost of producing the catalyst and decreasing the annual production capacity of the catalyst manufacturing plant. Furthermore, especially in larger ethylene oxide production plants, the total amount of silver required can be a significant capital demand, especially in light of the rising price of silver. Therefore, it would be desirable to have a highly efficient silver catalyst for the production of ethylene oxide having a silver content of less than about 25 weight percent, especially a catalyst that can be prepared using a single step of silver deposition. Summary of the Invention

[0008] The inventors selected and screened hundreds of promoter compositions and used regression models to fit experimental data to identify trends in catalyst activity and selectivity. It was found that through the use of carefully tuned amounts of specific alkali and oxyanion promoters, lower amounts of silver could be used without unduly sacrificing either the activity or selectivity of such catalysts. Compared to catalysts with a silver content of about 33 weight percent, catalysts of the present invention with less than about 25 weight percent silver actually have higher levels of promoter. This was a surprising result, since increasing promoter levels by linear scaling tend to decrease catalyst activity (see U.S. Pat. Nos. 9,649,621(B2) and 9,908,861(B2)). For catalysts with less than 25 percent silver, it was expected that promoter levels would need to be decreased to compensate for the expected activity penalty when decreasing the silver content from about 33 weight percent to less than 25 weight percent. Thus, in one aspect, the present invention is a supported silver catalyst prepared on an alumina-containing support. The support is a high purity alumina support having greater than about 80 weight percent alpha-alumina and less than about 30 parts per million by weight of an acid leachable alkali metal selected from lithium, sodium, potassium, and mixtures thereof, the weight percent of alumina and the concentration of the acid leachable alkali metal being calculated based on the weight of the support. On this support are deposited (A) silver in an amount of 16-25 weight percent of the catalyst, and (B) a solid promoter package including cesium, sulfate, rhenium, sodium, and optionally lithium. Preferably, manganese in an amount of 20-300 ppm is also deposited on the catalyst. For promoters other than manganese, the loading is expressed in units of millimoles of promoter per kilogram of catalyst, and the loading is scaled by a factor of Q, where Q is a unitless or dimensionless scaling factor equal to the surface area of ​​the alumina-containing support prior to deposition of silver and promoter, in units of meters squared per gram divided by meters squared per gram.

[0009] The amount of components in the solid promoter package deposited on the catalyst is C Cs / Q is in the range of 3.1 to 8.7 mmol / kg catalyst, and C Na / Q is in the range of 0.5 to 7.5 mmol / kg catalyst, and C S / Q is in the range of 0.3 to 3.2 mmol / kg catalyst, and C Re / Q is in the range of 2.4 to 6.9 mmol / kg catalyst, and C Li / Q is in the range of 0 to 35 mmol / kg catalyst, where C Cs , C Li , C Na , C S , and C Re are the amounts of cesium, lithium, sodium, sulfate, and rhenium, respectively, deposited on the support, expressed in mmol of promoter per kg of catalyst.

[0010] Furthermore, these amounts are balanced such that F1 / Q is in the range of 0.3 to 5.2 mmol / kg catalyst and F2 / Q is in the range of -5.1 to 6.3 mmol / kg catalyst, where F1 and F2 are linear combinations of the promoter stack loadings as defined by the following equation: F1=C Cs +0.032·C Li +0.47·C Na -(0.72 C S +0.94·C Re ), Equation 1 F2=C Cs -0.24°C Li -0.27°C Na +0.3 C S . equation 2

[0011] The above-described catalysts of the present invention demonstrate utility in a continuous process for the production of alkylene oxides directly from olefins and oxygen or oxygen-containing gases. Advantageously, the catalysts of the present invention demonstrate comparable levels of activity and / or efficiency compared to previously reported catalysts having higher levels of silver. [Brief description of the drawings]

[0012] [Figure 1] 1 is a graph showing the selectivity and activity of catalysts 11 to 45. [Diagram 2] 1 is a graph showing the selectivity and activity of catalysts 46 to 57. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The invention described herein provides a novel supported silver catalyst useful in the direct oxidation of alkylenes (olefins) such as ethylene to form alkylene oxides such as ethylene oxide with oxygen or an oxygen-containing gas, having a silver content of 25 weight percent or less, preferably 24 weight percent or less, 23 weight percent or less, or even 22 weight percent or less. It has been found that good results in terms of ethylene oxide production can be obtained when the silver content is at least 16 weight percent, preferably 17 weight percent, 18 weight percent, or even 19 weight percent. More specifically, the supported silver catalyst of the present invention comprises an alumina support containing less than about 30 parts per million by weight, preferably less than 25 parts per million by weight of an acid leachable alkali metal, the concentration of the alkali metal being calculated based on the weight of the support, the alkali metal being selected from lithium, sodium, potassium, and mixtures thereof.

[0014] The supported silver catalyst preferably comprises an alumina support comprising at least about 80 percent or more, preferably at least 90 percent, 95 percent, or even 98 percent alpha-alumina.

[0015] The carrier is 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, or 1.0m 2 It is preferred that the support have a surface area, expressed in units of square meters of surface area per gram of support, of at least 1.5 m / g. Generally, the higher the surface area, the better, but in some embodiments the support surface area is at least 1.5 m 2 / g, or 1.4m 2 / g, or 1.3m 2 / g or less. Suitable supports can be made according to procedures known in the art, such as those described in WO 2005 / 039757.

[0016] Onto this support are deposited: (A) silver, and (B) an additional solid promoter package containing cesium, sodium, sulfate, rhenium, and optionally lithium. Preferably, manganese is also deposited as a promoter.

[0017] The preferred level (i.e. amount) of promoter will depend in part on the surface area of ​​the support, expressed in units of square meters of surface area per gram of support, where the surface area of ​​the support is measured by nitrogen BET, and the pore volume and median pore diameter are measured by mercury intrusion porosimetry, as commonly known in the art, for example as shown in WO 2007 / 123932.

[0018] The amount of manganese, if present, should be in the range of 20 to 300 ppm by weight of the catalyst. Preferably, manganese is present in an amount of at least 50, 70, or 90 ppm, up to a maximum of 250, 200, or 150 ppm.

[0019] Cesium was added at concentrations ranging from 3.1, 3.7, 4.2, or 4.7 mmol per kg of catalyst up to 8.7, 8.4, 7.8, or 7.3 mmol per kg of catalyst. Cs / Q, where Q is unitless / dimensionless and equal to the surface area of ​​the alumina-containing support prior to deposition of silver and promoter, expressed in units of meters squared per gram divided by meters squared per gram; Cs is the amount of cesium deposited on the support, expressed in mmol of promoter per kg of catalyst.

[0020] The deposited sodium was measured at C levels ranging from 0.5, 1.2, 1.8, or 2.5 mmol / kg catalyst up to 7.5, 7.0, 6.5, or 6.0 mmol / kg catalyst. Na / Q, Nais the amount of sodium deposited on the support, expressed in mmol of promoter per kg of catalyst.

[0021] Sulfates are added at C levels of 0.3, 0.5, or 0.7 mmol / kg catalyst up to 3.2, 2.7, or 2.2 mmol / kg catalyst. S / Q, S is the amount of sulfate deposited on the support, expressed in mmol of promoter per kg of catalyst.

[0022] Rhenium is added at C levels ranging from 2.4, 2.8, or 3.3 mmol / kg catalyst up to 6.9, 6.4, or 6.0 mmol / kg catalyst. Re / Q, Re is the amount of rhenium deposited on the support, expressed in mmol of promoter per kg of catalyst.

[0023] Optionally, the deposited lithium is at a C concentration of 0, 3, 6, or 10 mmol / kg catalyst up to 35, 30, or 26 mmol / kg catalyst. Li / Q, Li is the amount of lithium deposited on the support, expressed in mmol of promoter per kg of catalyst.

[0024] It should be understood that the above amounts of the various promoters are those amounts which are deposited on the support and do not include amounts which may be initially present in the alumina-containing support, for example as impurities.

[0025] As will be appreciated by those skilled in the art, the above ranges of promoters are generally higher than those previously reported. It is surprising that activity is maintained under these conditions, since publications such as US Patent Nos. 9,649,621 (B2) and 9,908,861 (B2) suggest that high amounts of alkaline promoters generally reduce the activity of the catalyst.

[0026] The promoters are preferably balanced relative to one another, with F1 / Q preferably ranging from 0.3, 0.6, 1.0, 1.5, or 1.9 mmol / kg catalyst to 5.2, 4.9, 4.5, 4.1, or 3.7 mmol / kg catalyst, and F2 / Q preferably ranging from -5.1, -4.4, -3.6, -2.5, or -1.8 mmol / kg catalyst to 6.3, 5.6, 4.7, 3.5, or 2.7 mmol / kg catalyst, where F1 and F2 are defined in Equations 1 and 2, respectively.

[0027] The accelerator may be added in any convenient form, such as cesium hydroxide, cesium acetate, lithium acetate, ammonium sulfate, ammonium perrhenate, sodium acetate, and manganese nitrate. It may be desirable to premix the manganese accelerator, if present, with ethylenediaminetetraacetic acid (EDTA) before adding it to the silver impregnation solution.

[0028] In another aspect, the present invention provides a continuous process for producing alkylene oxide comprising contacting an alkylene, preferably ethylene, in the gas phase with oxygen or an oxygen-containing gas in the presence of a supported silver catalyst, the catalyst comprising any of the compositions identified herein above, and the contacting being carried out under process conditions sufficient to produce alkylene oxide.

[0029] The alkylenes (olefins) used in the process of the present invention are preferably characterized by the following structural formula I:

[0030] [ka] In the formula, R 1 and R 2 are each independently hydrogen and a lower monovalent alkyl radical, preferably C 1~6 Alkyl radicals, such as methyl, ethyl, propyl, butyl, and higher homologues up to 6 carbon atoms.1 and R 2 are each independently selected from hydrogen, methyl, and ethyl. More preferably, each R 1 and R 2 is hydrogen and the preferred olefin is ethylene. The corresponding alkylene oxide produced in the process of the present invention is preferably characterized by the following structure II:

[0031] [ka] In the formula, R 1 and R 2 are specified hereinbefore in relation to the reactant olefin. Most preferably, the alkylene oxide is ethylene oxide.

[0032] As is known from the prior art, oxygen can be supplied to the process as pure molecular oxygen or alternatively as an oxygen-containing gas, where the gas further contains one or more gaseous components that are essentially inert with respect to the oxidation process, such as gaseous diluents, such as nitrogen, helium, methane, and argon. A suitable oxygen-containing gas is, for example, air. Additionally, the oxygen-containing gas can contain one or more of the gaseous components including water, carbon dioxide, and various gaseous promoters and / or gaseous by-product inhibitors, as discussed herein below.

[0033] The relative volume ratio of alkylene to oxygen in the feed gas can range according to any of such known conventional values. Typically, the volume ratio of alkylene to oxygen in the feed is subject to flammability limits, as is well known in the art, and can vary from about 2 / 1 to about 10 / 1. Similarly, the amounts of inert gases, diluents, or other gaseous components, such as water, carbon dioxide, gaseous promoters, and gaseous by-product suppressors, can vary according to known conventional ranges found in the art.

[0034] The catalyst support used in carrying out the present invention may be selected from any of the known alumina supports, modified or unmodified, containing high purity alumina, specifically high purity alumina compositionally comprising greater than about 80 weight percent, preferably greater than about 90 weight percent, more preferably greater than about 95 weight percent, and most preferably greater than about 98 weight percent alumina. The balance of the composition typically includes either zirconium silicate (zircon), other refractory silicates, silica, or other metal oxides. In terms of phase composition, the alumina preferably comprises alpha phase alumina (α-alumina), more preferably greater than about 99 percent alpha phase alumina (α-alumina). As a requirement, the high purity alumina support should contain less than about 30 ppm by weight, preferably less than about 25 ppm by weight, more preferably less than about 20 ppm by weight of acid leachable alkali metal, the concentration of the alkali metal being calculated based on the weight of the support, the alkali metal being selected from lithium, sodium, potassium, and mixtures thereof. Preferably, the high purity alumina support contains less than about 30 ppm by weight of acid leachable sodium, more preferably less than about 25 ppm by weight.

[0035] In some embodiments, the alumina support also contains zirconium silicate (zircon), more preferably in any amount up to about 4, 3, or 2 weight percent calculated on the weight of the support.

[0036] There is no limit to the manner in which low levels of alkali metals (Li, Na, K) that form a compositional part of the high purity alumina support are incorporated into the support, if any alkali is present. Typically, these alkali metals are introduced into the support during its synthesis, for example as impurities in one or more of the raw materials or as contaminants in the calcination environment, however, other methods of achieving such levels of these alkali metals may be possible. What is important is that the catalyst of the present invention is prepared starting from a preformed high purity alumina support having less than about 30 ppm of acid leachable alkali metals selected from lithium, sodium, potassium, and mixtures thereof. The preformed high purity alumina support is then treated to intentionally deposit, i.e., add, to it, silver and a solid promoter package including cesium, sodium, sulfate, rhenium, and optionally lithium and / or manganese.

[0037] Representative examples of materials that may be used as high purity alumina in accordance with the present invention include supports such as those manufactured by Sud Chemie, Inc., Louisville, Ky., and Saint-Gobain NorPro Corp., Akron, Ohio, and are available from other suppliers.

[0038] Suitable shapes for the high purity alumina support include any of a wide variety of shapes known for such supports or supports, including pills, chunks, tablets, pieces, pellets, rings, spheres, wagon wheels, toroids having star-shaped inner and / or outer surfaces, and the like, of sizes suitable for use in fixed bed reactors. Conventional commercial fixed bed ethylene oxide reactors are typically in the form of a plurality of parallel elongated tubes (preferred shells) packed with catalyst, having an outer diameter of about 1 to 3 inches (2.5 to 7.5 cm) and a length of about 15 to 45 feet (4.5 to 13.5 m). In such fixed bed reactors, it is desirable to use supports formed in round shapes, such as spheres, pellets, rings, tablets, etc., having diameters of about 0.1 inches (0.25 cm) to about 0.8 inches (2 cm).

[0039] There are many well-known methods for preparing alumina supports suitable for use in the alkylene oxide catalyst of the present invention. Some of these methods are described, for example, in International Publication No. 2005 / 039757(A1) and U.S. Patent Nos. 4,994,587, 4,994,588, and 5,504,053, which are incorporated herein by reference. Preferably, an alumina support of at least 90 percent purity having the desired properties (e.g., desired morphology, surface area, pore volume, and / or pore size distribution) can be prepared by compounding (mixing) raw materials, extruding, drying, and calcining at high temperature. In this case, the raw materials usually include one or more α-alumina powders with different properties, optionally materials that may be added to provide physical strength, and optionally burnout materials (usually organic compounds) used to provide the desired porosity after removal by calcination, with the proviso that the binder and burnout materials do not add alkali metals (Li, Na, K) to the carrier in amounts that exceed the required upper limit of less than about 30 ppm by weight. The level of impurities in the final carrier is largely determined by the purity of the raw materials used and their volatility during the calcination process. Common impurities include silica, alkali metal oxides, and / or alkaline earth metal oxides, as well as trace amounts of metal and / or non-metal containing additives.

[0040] Another known method for preparing high purity alpha-alumina with suitable properties includes mixing zirconium silicate with boehmite alumina (AlOOH) and / or gamma-alumina, peptizing the boehmite alumina and / or gamma-alumina in an acidic mixture containing halide anions (preferably fluoride anions) to provide an alumina halide, forming the peptized alumina halide (e.g., by extrusion or pressing) to provide a formed peptized alumina halide, drying the formed peptized alumina halide to provide a dried formed alumina, and calcining the dried formed alumina to provide an alpha-alumina support pill. When an alpha-alumina support prepared as described in this section is used, it is important that the alumina peptized with the acidic mixture containing halide anions is calcined prior to deposition of silver or a promoter metal, since halides are required to form the desired platelets of alpha-alumina, as described herein below.

[0041] The high purity α-alumina support for use in the present invention preferably has a thickness of at least about 0.5 m 2 / g, more preferably at least about 0.7m 2 / g. The surface area is typically about 10 m 2 / g or less, and in most cases, about 5m 2 / g, 2m 2 / g, or even 1.5m 2 The high purity alumina support preferably has a particle size of at least about 0.5 cm 3 / g, more preferably about 0.5 cm 3 / g ~ approx. 2.0cm 3 / g pore volume, and a median pore diameter of about 1 to about 50 microns. Preferably, the high purity alumina has a crush strength of greater than about 12 pounds. The high purity alpha-alumina preferably comprises particles having at least one substantially flat major surface (some particles having two or more flat surfaces), each of which has a lamellar or platelet morphology approximating the shape of a hexagonal plate, at least 50 percent of which (by number) have a major dimension less than about 50 microns.

[0042] The catalysts of the present invention for producing alkylene oxides, such as ethylene oxide or propylene oxide, may be prepared using the high purity alpha-alumina described above by impregnating the support with a solution of one or more silver compounds, as is well known in the art. A solid promoter package may be impregnated simultaneously with the silver impregnation, before the silver impregnation, or after the silver impregnation. It is preferred that the silver and promoter impregnations are carried out simultaneously.

[0043] The art discloses the concept of "promoters", i.e., materials that, when present in combination with catalytic silver, act to benefit one or more aspects of catalyst performance or otherwise promote the ability of the catalyst to make the desired alkylene oxide product, preferably ethylene oxide or propylene oxide. Although such promoters are not generally considered catalytic materials themselves, the presence of such promoters in the catalyst has been shown to have one or more beneficial effects on catalyst performance, such as improving the rate or amount of production of the desired product (e.g., by improving activity and / or efficiency), reducing the temperature required to achieve a suitable reaction rate, and / or reducing the rate or amount of undesirable by-product reactions. Competing reactions occur simultaneously in the reactor, and an important factor in determining the effectiveness of the overall process is the measure of control of these competing reactions. A material that is referred to as a promoter of a desired reaction may be an inhibitor of another reaction, e.g., a combustion reaction. What is important is that the effect of the promoter on the overall reaction is favorable to the efficient production of the desired product, in this case alkylene oxide, more preferably ethylene oxide.

[0044] It has been found that, when the concentrations of the various promoter components are carefully controlled, the use of the catalyst to produce alkylene oxides, particularly ethylene oxide, can result in the desired activity and selectivity levels, despite a lower amount of silver deposited on the catalyst. The concentrations of the components of the solid promoter package (cesium, sodium, sulfate, rhenium, and optionally lithium and / or manganese), as described above, are provided in promoting amounts. In this context, the term "promoting amount" refers to an amount of promoter that provides an improvement in one or more of the catalytic properties of the catalyst when compared to a comparative or reference catalyst containing the same components in the same amounts but without the promoting component, and when compared under the same (controlled) process conditions. Examples of catalytic properties include, among others, resilience, operability (resistance to runaway), activity, conversion (e.g., conversion of alkenes), efficiency (selectivity), stability, and yield. Preferably, the promoters are provided in a "synergistic combination". The term "synergistic combination" refers to the selection of appropriate amounts of promoters that can achieve greater efficiency than that obtained under similar operating conditions from each catalyst prepared from the individual components of the solid promoter package. U.S. Pat. No. 4,913,243, incorporated herein by reference, teaches silver-supported catalysts containing a synergistic combination of cesium and at least one other alkali metal selected from the group consisting of lithium, sodium, potassium, and rubidium. Although such patents describe efficiency equations that may be useful for identifying synergistic combinations of cesium and other alkali metals, the efficiency equations are not the only way to characterize synergistic combinations, but only represent one way.

[0045] Well-known methods may be used to analyze the amount of silver and the individual components of the solid promoter package deposited on the alumina support. One skilled in the art may determine the amount of any of these deposited components, for example, using a mass balance. As an example, if the alumina support is weighed before and after deposition of the silver and alkali metal-containing compounds, the difference between the two weights will equal the amount of silver and alkali metal-containing compounds deposited on the support, from which the amount of alkali metal deposited can be calculated. Additionally, the amount of silver and alkali metal-containing compounds deposited can be calculated based on the ratio of the concentration of the silver and alkali metal-containing compounds in the impregnation solution to the weight taken from the impregnation solution. Alternatively, any suitable analytical technique for determining elemental composition, such as inductively coupled plasma (ICP) or X-ray fluorescence (XRF) spectroscopy, may be used to determine the amount of deposited components. As an example, the alumina support can be analyzed by XRF to determine the amount of cesium present in the support. After impregnation with the cesium-containing compound, the impregnated support can be analyzed again by XRF to determine the total amount of cesium present in and deposited on the support. The difference in the measurements reflects the amount of cesium deposited on the support.

[0046] In addition to the solid promoter package described hereinabove, a gaseous promoter may be used with the catalyst of the present invention, if desired. A gaseous promoter is a gas-phase compound and / or mixture thereof that is introduced into a reactor for the production of alkylene oxide (preferably ethylene oxide) using gas-phase reactants such as ethylene and oxygen. Such promoters are also referred to as modifiers, inhibitors, or enhancers, and act in conjunction with or in addition to the solid promoter to further improve the performance of a given catalyst. As is well known in the art, one or more chlorine-containing components are typically used as gaseous promoters. Other halide-containing components may also be used to achieve similar effects.

[0047] The solid promoter package is generally added to the catalyst as a chemical compound prior to its use. As used herein, the term "compound" refers to the combination of a particular element with one or more different elements by surface and / or chemical bonds, such as ionic and / or covalent and / or coordinate bonds. The term "ionic" or "ion" refers to a chemical moiety that is electrically charged, with "cationic" or "cation" being positive and "anionic" or "anion" being negative. The term "oxyanionic" or "oxyanion" refers to a negatively charged moiety that contains at least one oxygen atom in combination with another element. Thus, an oxyanion is an oxygen-containing anion. It is understood that ions do not exist in a vacuum, but when added to a catalyst as a compound, they are found in combination with a charge-balancing counterion. Once in the catalyst, the form of the promoter is not necessarily known, and the promoter may exist without the counterion added during the preparation of the catalyst. For example, a catalyst made with cesium hydroxide may be analyzed to contain cesium in the final catalyst but no hydroxide. Similarly, compounds such as alkali metal oxides, e.g., cesium oxide, are not ionic but may be converted to ionic compounds during catalyst preparation or use. For ease of understanding, the solid promoters are referred to in terms of their cations and anions, regardless of their form in the prepared catalyst and / or under reaction conditions.

[0048] Generally, the support is impregnated with a catalytic amount of silver, which is any amount of silver capable of catalyzing the direct oxidation of an alkylene to the corresponding alkylene oxide with oxygen or an oxygen-containing gas. In making such catalysts, the support is typically impregnated (one or more times) with one or more silver compound solutions sufficient to load the support with the desired range of silver from about 16 weight percent up to about 25 weight percent, based on the weight of the catalyst. Most preferably, the support is impregnated once with a solution containing a silver compound to obtain the desired silver content.

[0049] The silver solution used to impregnate the support preferably consists of a silver compound in a solvent or complexing / solubilizing agent, such as silver solutions disclosed in the art. The particular silver component used may be selected from, for example, silver complexes, silver nitrate, silver oxide, or silver carboxylates, such as silver acetate, oxalate, citrate, phthalate, lactate, propionate, butyrate, and higher fatty acid salts. Silver oxide complexed with an amine is another preferred form of silver for use in the present invention.

[0050] A wide variety of solvents or complexing / solubilizing agents can be used to solubilize silver to the desired concentration in the impregnation medium. Among those disclosed as suitable for this purpose are lactic acid, ammonia, alcohols such as ethylene glycol, and amines and aqueous mixtures of amines.

[0051] For example, silver oxide (AgO) can be advantageously dissolved in a solution of oxalic acid and ethylenediamine such that the resulting impregnation solution contains approximately 26% silver oxide, 18% oxalic acid dihydrate, 17% ethylenediamine, 6% monoethanolamine, and 31% water.

[0052] About 0.7 cm of such a solution 3 Vacuum impregnation on a 200 / g porous support typically results in a catalyst containing about 20 wt. % silver, based on the total weight of the catalyst. Whereas previously it was desired to obtain catalysts having silver loadings in excess of about 25 or 30 percent and higher, it was generally necessary to subject the support to at least two or more sequential impregnations of silver, with or without promoters, until the desired amount of silver was deposited on the support, the supported catalysts of the present invention may be produced using a single step of silver impregnation, thereby greatly simplifying the process for producing the catalyst.

[0053] The silver particle size in the final catalyst is important, but the range is not narrow. Suitable silver particle sizes can range from about 10 angstroms to about 10,000 angstroms in diameter. Preferred silver particle sizes range from greater than about 100 angstroms to less than about 5,000 angstroms in diameter. It is desirable for the silver and various components of the solid promoter package to be relatively uniformly dispersed on the alumina support.

[0054] A preferred procedure for depositing the silver catalytic material and the solid promoter package includes (1) impregnating a porous alumina support according to the present invention with a solution containing a solvent or solubilizing agent, a silver complex, and a solid promoter package, and (2) thereafter treating the impregnated support to convert the silver salt to silver metal and result in the deposition of silver and promoter on the exterior and interior pore surfaces of the support. The deposition of silver and promoter is generally accomplished by heating the support at an elevated temperature to evaporate the liquid within the support and result in the deposition of silver and promoter on the interior and exterior support surfaces.

[0055] Alternatively, a coating of silver and a solid promoter package may be formed on the support from an emulsion or slurry containing the metal components, followed by heating the support as previously described herein. However, impregnation of the support is generally the preferred technique for silver deposition, as it utilizes silver more efficiently than coating procedures, which generally do not result in substantial silver deposition on the interior surfaces of the support. In addition, coated catalysts are more susceptible to silver loss due to mechanical abrasion.

[0056] Similar to silver deposition, soluble salts of the components of the solid accelerator package may be dissolved in one or more solvents and / or solubilizers and deposited on the support, preferably by impregnation. The order of impregnation or deposition of silver and the components of the solid accelerator package on the surface of the support may vary. Thus, impregnation and deposition of silver, cesium, sodium, sulfate, rhenium, and optionally lithium and / or manganese may be performed simultaneously or sequentially, e.g., cesium and sodium may be deposited before, during, or after silver deposition on the support. The individual components of the solid accelerator package may be deposited together or sequentially. For example, silver may be deposited first, followed by simultaneous or sequential deposition of cesium, lithium (if used), sulfate, and rhenium (or combinations thereof), or alternatively, cesium may be deposited first, followed by simultaneous or sequential deposition of silver and lithium (if used), sulfate and rhenium, or alternatively, lithium, if used, may be deposited first, then simultaneous or sequential deposition of silver and cesium, sulfate and rhenium, etc. When two or more impregnations are used, the impregnated support is typically dried, or calcined and / or roasted between each successive impregnation to ensure deposition of the metal on the support.

[0057] The support impregnated with silver and a solid promoter package containing cesium, sodium, sulfate, rhenium, and optionally lithium and / or manganese is then calcined or roasted in air at a temperature ranging from about 200° C. to about 600° C. and atmospheric pressure for a time ranging from about 0.01 to about 12 hours. Temperatures of 475° C. to 525° C. for 5 to 20 minutes are generally preferred. Alternatively, calcination may be carried out in two or more distinct steps, with the first step generally being carried out at a lower temperature.

[0058] The rhenium component may be provided in various forms, for example, as the metal, as a covalent compound, as a cation, or as an anion. The rhenium species that provides the improved efficiency and / or activity is uncertain and may be an added component or may be a component generated during the preparation or use of the catalyst. Examples of rhenium compounds include rhenium salts, such as rhenium halides, rhenium oxyhalides, rhenates, perrhenates, oxides of rhenium, and acids of rhenium. However, alkali metal perrhenates, ammonium perrhenate, alkaline earth metal perrhenates, silver perrhenate, other perrhenates, and rhenium heptaoxide may also be suitably utilized, provided that in the case of the alkali metal perrhenates, the amount of alkali metals therein (Cs and / or Rb, and Na and / or K) is taken into account when assessing the total amount of these cations deposited on the support. Rhenium heptaoxide, Re2O7, when dissolved in water, hydrolyzes to perrhenic acid, HReO4, or hydrogen perrhenate. Thus, for purposes of this specification, rhenium heptoxide may be considered to be a perrhenate, i.e., monoanionic ReO4.

[0059] Another class of preferred promoters and catalyst stabilizers that may be used in the present invention includes manganese components. In many cases, the manganese component may improve the activity, efficiency, and / or stability of the catalyst. The manganese species that provides the improved activity, efficiency, and / or stability is not certain and may be a component added or generated during catalyst preparation or use as a catalyst. Manganese components include, but are not limited to, manganese acetate, ammonium manganese sulfate, manganese citrate, manganese dithionate, manganese oxalate, manganese nitrate, manganese sulfate, and manganate anions, such as permanganate anion, and mixtures thereof. To stabilize the manganese component in certain impregnation solutions, it may be necessary to add a chelating compound, such as ethylenediaminetetraacetic acid (EDTA) or a suitable salt thereof.

[0060] The promotion effect provided by the solid promoter package and optional gas phase promoter can be influenced by many variables, such as the reaction conditions, the catalyst preparation technique, the surface area and pore structure, and the surface chemistry of the support, silver, and the concentration of promoter present in the catalyst.

[0061] The present invention is applicable to epoxidation reactions in any suitable reactor, such as fixed bed reactors, continuous stirred tank reactors (CSTRs), and fluidized bed reactors; a wide variety of reactors are well known to those skilled in the art and need not be described in detail herein. The desirability of increasing ethylene conversion by recycling unreacted feedstock, or using a single pass system, or using continuous reaction and reactors in a series arrangement, can also be readily determined by those skilled in the art. The particular operating mode selected is usually determined by the economics of the process. The conversion of olefins (alkylenes), preferably ethylene, to olefin oxides, preferably ethylene oxide, can be carried out, for example, by continuously introducing a feed stream containing an alkylene (e.g., ethylene) and oxygen or an oxygen-containing gas into a catalyst-containing reactor at a temperature of about 200° C. to about 300° C. and a pressure that can vary within the range of about 5 atmospheres (506 kPa) to about 30 atmospheres (3.0 MPa) depending on the desired mass rate and productivity. The residence time in a large-scale reactor is generally from about 0.1 seconds to about 5 seconds. Oxygen can be supplied to the reaction in an oxygen-containing stream such as air, or as commercially available oxygen, or as oxygen-enriched air. The resulting alkylene oxide, preferably ethylene oxide, is separated and recovered from the reaction product using conventional methods.

[0062] Prior to alkylene oxide production, it is generally desirable to activate or commission the catalyst, as is generally known to those skilled in the art. One suitable activation protocol is to expose the supported catalyst at 245° C. with a near-optimum ethyl chloride concentration for 2-5 days to rapidly achieve optimal performance.

[0063] The catalysts disclosed herein may be used under a wide variety of process conditions, as is well known to those skilled in the art.

[0064] The following examples are provided for the purpose of illustrating the present invention, but are not intended to limit the present invention in any way. Those skilled in the art will recognize various permutations and modifications of the examples that fall within the scope of the present invention. EXAMPLES

[0065] A series of high purity alpha-alumina supports having hollow shape morphology and greater than about 80 weight percent alpha-alumina and less than about 30 parts per million by weight of acid leachable alkali metals (specifically lithium, sodium, and potassium), the weight percent of alumina and the concentration of acid leachable alkali metals being calculated by weight of the support, are available from Saint-Gobain NorPro. Table 1 below shows the properties of supports A through F.

[0066] [Table 1]

[0067] Silver Compound Solution The silver impregnation solution is prepared according to the procedure described in U.S. Patent Application Publication No. 2009 / 0177000(A1) and contains approximately 27% by weight silver oxide, 18% by weight oxalic acid dihydrate, 17% by weight ethylenediamine, 6% by weight monoethanolamine, and 31% by weight water. To this pre-prepared silver solution, the individual promoter solutions are added in pre-calculated amounts to create the desired promoter composition on the final catalyst.

[0068] Synthesis by accelerator solution, vacuum impregnation Manganese nitrate (Mn(NO3)2), diammonium ethylenediaminetetraacetate ((NH4)2H2(EDTA)), cesium hydroxide (CsOH), lithium acetate (LiOCOCH3), and ammonium sulfate ((NH4)2SO4) are used as premade solutions. The manganese and EDTA solutions are premixed before being added to the premade silver solution. The CsOH solution is typically diluted with deionized water to the desired cesium concentration before use. A sodium acetate (NaOCOCH3) accelerator solution is made by dissolving the salt in deionized water. An ammonium perrhenate (NH4ReO4) accelerator solution is prepared by dissolving the salt in deionized water that is gently heated to 40-50 °C with stirring.

[0069] Catalyst synthesis by vacuum impregnation The catalysts of Examples 1-10 are synthesized by vacuum impregnation. The synthesis apparatus consists of a lower vacuum vessel, which can be sealed at the top by a Teflon stopper connected to a second vessel equipped with a stopcock. The synthesis begins by loading unladen alumina-containing support pellets into the lower vacuum vessel. The lower vessel is then sealed and placed under vacuum for 15 minutes. After evacuation, a silver impregnation solution with the desired promoter concentration is added to the upper vessel. The stopcock is opened to introduce the promoted silver solution under vacuum to the support. The vacuum is then released and the support is left immersed in the impregnation solution for 15 minutes, followed by draining for another 15 minutes. The freshly impregnated support is placed in a single layer on a stainless steel mesh tray and calcined in an air oven at 500°C for 10 minutes. The catalyst is cooled and weighed to estimate the Ag loading after impregnation.

[0070] Catalyst synthesis by incipient wetness impregnation The catalysts of Examples 11-45 are synthesized by incipient wetness impregnation method. Unpromoted silver-impregnated pills (21.5 wt% silver, prepared using a vacuum impregnation method similar to that described above using Carrier A) are crushed, sieved to 30-50 mesh, divided into 500 mg lots, and placed in a synthesis tube. A promoter solution is prepared using deionized water, cesium hydroxide, lithium acetate, sodium acetate, ammonium sulfate, ammonium perrhenate, and manganese nitrate tetrahydrate. The manganese solution is stabilized with diammonium salt of ethylenediaminetetraacetic acid and monoethanolamine. The promoter solution is combined and then added to the silver-impregnated powder, followed by mixing to achieve homogeneity. After impregnation, the samples are dried at 80°C for 30 minutes and then calcined at 500°C for 10 minutes in a box oven under air flow.

[0071] Elemental analysis of catalysts synthesized by vacuum impregnation Elemental analysis was performed by X-ray fluorescence spectrometry (XRF) for silver, cesium, sulfate, rhenium, and manganese, and by inductively coupled plasma optical emission spectrometry (ICP-OES) for lithium and sodium.

[0072] Testing Protocol, Continuously Stirred Tank Reactor For catalytic activity testing in a back-mixed Berty-type autoclave reactor (RotoBerty), a 30 cm 3(about 20 g) of catalyst is loaded. The reactor is heated to 245°C under nitrogen flow. As soon as the temperature reaches 220°C, the feed gas is introduced. The reaction conditions are 7.1 standard cubic feet per hour (scfh) total flow (201 standard liters / hr), gas hourly space velocity (GHSV) of about 6800 hr-1, total pressure of 275 psig (1900 kPa gauge), and gas inlet concentrations (by deposition) of 30% C2H4, 0.7% C2H6, 8% O2, 1% CO2, 4-5 ppm ethyl chloride (ECL), the remainder nitrogen. The catalyst is operated at these "trial run" conditions for 2-3 days unless otherwise specified in the following examples. After catalyst activation, the temperature is reduced to 235°C and optimization of the gas phase promoter is performed by varying the inlet ethyl chloride concentration from low to high. Cl optimization may also be performed using outlet concentration control at 28.3% C2H4, 6.4% O2, and 1.5% CO2. At each ethyl chloride concentration, performance is stabilized and average values ​​are recorded. Optimal performance is reported as the selectivity and activity (ΔEO) at the inlet ECl concentration where selectivity is maximized. ΔEO is the difference between the outlet ethylene oxide concentration and the inlet ethylene oxide concentration, corrected for the change in molar volume of the entire reactor, measured in mole percent. It is the reactor inlet and outlet concentrations in mole percent of ethylene oxide (EO, respectively). 入口 and E.O. 出口 ) is calculated as follows: ΔEO% = SF × EO 出口 -EO 入口 The term "SF" or "shrinkage factor" refers to the net volume reduction that occurs due to the production of ethylene oxide. For every mole of ethylene oxide produced, there is a net reduction of 0.5 moles of total gas, resulting in a corresponding reduction in volumetric flow rate. SF is typically calculated as follows: (200 + EO 入口 )÷(200+EO 出口 ), where EO 入口 and E.O. 出口 are the concentrations in mole percent of ethylene oxide in the reactor inlet and outlet gas mixtures, respectively.

[0073] Test Protocol, Plug Flow Reactor Catalyst testing for high throughput evaluation was carried out in a High Pressure Reactor Assembly Module (HPRAM) system, as described, for example, in U.S. Patent No. 9,649,621. The HPRAM reactor system includes a gas supply system, 48 reactors, two outlet modules, and three analyzers (Siemens MAXUM-II gas chromatographs (GC)). Of the 48 reactors, seven are left blank to determine gas inlet concentrations.

[0074] The test was performed at a constant catalyst bed volume (V catalyst bed = 0.1498 cm 3 The reactor is run at 100° C.), constant flow (19.6 standard cubic centimeters per minute), and constant gas hourly space velocity (GHSV=7850 / hr). The catalyst is loaded into the reactor in the form of a powder (30 / 50 mesh) without an inert diluent. The catalyst is loaded by mass into the reactor tube using the formula shown below. Packing mass (mg) = V catalyst bed PD support 100% / (100%-AGWT) where PD support is the packing density of the support listed in Table 1 and AGWT is the silver content of the catalyst in weight percent. Note that the use of total pill packing density for these tests is a model for larger scale tests. Catalyst loading masses are 100.0 mg and 93.8-100.3 mg for the tests reported in Tables 6 and 8, respectively.

[0075] The reactor is loaded with catalyst and then heated under inert gas flow (either helium or nitrogen) followed by introduction of the feed gas, excluding oxygen, into the reactor. The oxygen is added last (typically after 2-3 minutes) to avoid any opportunity of forming a flammable mixture in the system. The gas pressure and gas flow are then held constant at 10 barg and 19.6 standard cubic centimeters per minute for the duration of the test.

[0076] The catalyst tests reported in Table 6 (catalysts 11-45) are carried out as follows: After a 2 day activation period (245°C, 28 vol.% inlet ethylene, 4.8 vol.% inlet oxygen, 2.0 vol.% inlet carbon dioxide, 4 ppmv inlet ethyl chloride, 0.14 vol.% inlet ethane, 11 vol.% inlet methane, the remainder inerts), the temperature is reduced to 235°C and the gas inlet is adjusted to 32 vol.% ethylene, 7.6 vol.% oxygen, 1.5 vol.% carbon dioxide, 0.14 vol.% ethane, 11 vol.% methane, and various amounts of ethyl chloride promoter. Optimization of the gas phase promoter is carried out in a low to high plateau step with ethyl chloride ranging from 0.5 to 6.0 ppmv.

[0077] The catalyst tests reported in Table 8 (catalysts 46-57) are averages over N=2-5 reactors. These tests are carried out as follows: After a 2-day activation period (245° C., 27 vol. % inlet ethylene, 4.7 vol. % inlet oxygen, 1.7 vol. % inlet carbon dioxide, 1.4 ppmv inlet ethyl chloride, 0.12 vol. % inlet ethane, 11 vol. % inlet methane, the remainder inerts), the gas inlet is adjusted to 32 vol. % ethylene, 7.4 vol. % oxygen, 1.3 vol. % carbon dioxide, 1.8 vol. % ethane, 0.7 ppmw ethyl chloride, and 11 vol. % methane. After 5 hours of operation (T=245° C. and 1.8 vol. % ethane), the temperature is reduced to 235° C. and the ethane inlet is reduced to 0.12 vol. Optimization of the vapor phase promoter is then performed in a low to high plateau step using ethyl chloride ranging from 0.96 to 3.84 ppmv.

[0078] Catalyst produced Catalyst 1 50 g of support A are converted to "catalyst 1" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution:

[0079] 200g silver solution (27.41% Ag) 0.1987g Mn(NO3)2 solution (0.1570g Mn / g solution) 1.0963 g of (NH4)2H2(EDTA) solution (0.4030 g of EDTA / g solution) 2.4931g of CsOH solution (0.1100g of Cs / g of solution) 0.6179g LiOCOCH3 solution (0.0255g Li / g solution) 0.3472g NaOCOCH3 solution (0.0551g Na / g solution) 0.1238g of (NH4)2SO4 solution (0.2908g of SO4 / g solution) 9.4962g of NH4ReO4 solution (0.0320g of Re / g solution)

[0080] The produced catalyst contained 19.2 wt% Ag as determined by XRF. Target promoter concentrations for all promoters are listed in Table 3. Table 4 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0081] Catalyst 2 50 g of support B are converted to "catalyst 2" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (27.41% Ag) 0.1912 g Mn(NO3)2 solution (0.1570 g Mn / g solution) 1.0551 g of (NH4)2H2(EDTA) solution (0.4030 g EDTA / g solution) 2.9531g of CsOH solution (0.1100g of Cs / g of solution) 0.7319g LiOCOCH3 solution (0.0255g Li / g solution) 0.4551g NaOCOCH3 solution (0.0498g Na / g solution) 0.1467g of (NH4)2SO4 solution (0.2908g of SO4 / g solution) 11.1440 g of NH4ReO4 solution (0.0323 g Re / g solution)

[0082] The produced catalyst contained 20 wt % Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 3.

[0083] Catalyst 3 50 g of support C are converted into "catalyst 3" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (26.8% Ag) 0.1883g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.0399g of (NH4)2H2(EDTA) solution (0.4001g EDTA / g solution) 1.5583g of CsOH solution (0.1090g of Cs / g of solution) 0.6911g LiOCOCH3 solution (0.0255g Li / g solution) 0.4214g NaOCOCH3 solution (0.0491g Na / g solution) 0.0920g of (NH4)2SO4 solution (0.2944g of SO4 / g of solution) 5.2368g of NH4ReO4 solution (0.0318g of Re / g of solution)

[0084] The produced catalyst contained 21 wt % Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 3.

[0085] Catalyst 4 50 g of support C were converted to "Catalyst 4" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (26.8% Ag) 0.1882g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.0397 g of (NH4)2H2(EDTA) solution (0.4001 g of EDTA / g solution) 1.8695g of CsOH solution (0.1090g of Cs / g of solution) 1.7325g LiOCOCH3 solution (0.0255g Li / g solution) 0.2407g NaOCOCH3 solution (0.0491g Na / g solution) 0.1002g of (NH4)2SO4 solution (0.2944g of SO4 / g of solution) 5.2689g of NH4ReO4 solution (0.0316g of Re / g of solution)

[0086] The produced catalyst contained 20 wt % Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 3.

[0087] Catalyst 5 50 g of support C are converted into "catalyst 5" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (27.3% Ag) 0.1921g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.0607 g of (NH4)2H2(EDTA) solution (0.4001 g of EDTA / g solution) 1.9429g of CsOH solution (0.1105g of Cs / g of solution) 1.0626g LiOCOCH3 solution (0.0255g Li / g solution) 0.3661g NaOCOCH3 solution (0.0491g Na / g solution) 0.1018g of (NH4)2SO4 solution (0.2944g of SO4 / g of solution) 6.9093g of NH4ReO4 solution (0.0316g Re / g solution)

[0088] The produced catalyst contained 19.7 wt% Ag as determined by XRF. Target promoter concentrations for all promoters are listed in Table 3. Table 4 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0089] Catalyst 6 50 g of support D are converted into "catalyst 6" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (27.37% Ag) 0.1926g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.0639 g of (NH4)2H2(EDTA) solution (0.4001 g of EDTA / g solution) 1.9487g of CsOH solution (0.1105g of Cs / g of solution) 1.3732g LiOCOCH3 solution (0.0255g Li / g solution) 0.5383g NaOCOCH3 solution (0.0500g Na / g solution) 0.1429g of (NH4)2SO4 solution (0.2944g of SO4 / g solution) 7.8562g of NH4ReO4 solution (0.0316g of Re / g of solution)

[0090] The produced catalyst contained 19.5 wt% Ag as determined by XRF. Target promoter concentrations for all promoters are listed in Table 3. Table 4 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0091] Catalyst 7 50 g of support F are converted into "catalyst 7" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (27.37% Ag) 0.2020g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.1154 g of (NH4)2H2(EDTA) solution (0.4001 g EDTA / g solution) 1.8693g of CsOH solution (0.1105g of Cs / g of solution) 1.0528g LiOCOCH3 solution (0.0255g Li / g solution) 0.2411g NaOCOCH3 solution (0.0500g Na / g solution) 0.1014g of (NH4)2SO4 solution (0.2944g of SO4 / g solution) 5.3403g of NH4ReO4 solution (0.0316g Re / g solution)

[0092] The produced catalyst contained 16.5 wt% Ag as measured by XRF. Target promoter concentrations for all promoters are listed in Table 3. Table 4 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0093] Catalyst 8 50 g of support E are converted into "catalyst 8" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 200g silver solution (27.3% Ag) 0.2017 g of Mn(NO3)2 solution (0.1560 g Mn / g solution) 1.1140 g of (NH4)2H2(EDTA) solution (0.4001 g EDTA / g solution) 1.9760g of CsOH solution (0.1105g of Cs / g of solution) 1.1105g LiOCOCH3 solution (0.0255g Li / g solution) 0.2579g NaOCOCH3 solution (0.0491g Na / g solution) 0.1074g of (NH4)2SO4 solution (0.2944g of SO4 / g solution) 5.6454g of NH4ReO4 solution (0.0316g of Re / g of solution)

[0094] The produced catalyst contained 17.1 wt% Ag as determined by XRF. Target promoter concentrations for all promoters are listed in Table 3. Table 4 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0095] Catalyst 9 50 g of Carrier D is converted to "Catalyst 9" according to the vacuum impregnation method presented above, except for the change in the calcination treatment. Following impregnation and draining, the wet pill is treated in an air oven at 110° C. for 10 minutes before calcining at 500° C. for 10 minutes. The following amounts are used to make the impregnation solution: 200g silver solution (27.37% Ag) 0.2022g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.1167 g of (NH4)2H2(EDTA) solution (0.4001 g EDTA / g solution) 1.6208g of CsOH solution (0.1105g of Cs / g of solution) 0.7314g LiOCOCH3 solution (0.0255g Li / g solution) 0.4388g NaOCOCH3 solution (0.0500g Na / g solution) 0.0969g of (NH4)2SO4 solution (0.2944g of SO4 / g of solution) 5.5549g of NH4ReO4 solution (0.0316g of Re / g of solution)

[0096] The produced catalyst contained 21.1 wt% Ag as determined by XRF. Target promoter concentrations for all promoters are listed in Table 3. Table 4 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0097] Catalyst 10 50 g of Carrier D is converted to "Catalyst 10" according to the vacuum impregnation method presented above, except for the change in the calcination treatment. Following impregnation and draining, the wet pill is treated in an air oven at 90° C. for 90 minutes before being calcined at 500° C. for 10 minutes. The following quantities are used to generate the impregnation solution: 200g silver solution (27.37% Ag) 0.1901g Mn(NO3)2 solution (0.1560g Mn / g solution) 1.0502 g of (NH4)2H2(EDTA) solution (0.4001 g EDTA / g solution) 1.5243g of CsOH solution (0.1105g of Cs / g of solution) 0.6878g LiOCOCH3 solution (0.0255g Li / g solution) 0.4127g NaOCOCH3 solution (0.0500g Na / g solution) 0.0911g of (NH4)2SO4 solution (0.2944g of SO4 / g of solution) 5.2241g of NH4ReO4 solution (0.0316g of Re / g of solution)

[0098] The produced catalyst contained 22.4 wt% Ag as determined by XRF. The target promoter concentrations for all promoters are listed in Table 2. Table 3 shows a comparison of the target promoter concentrations to the analyzed promoter concentrations.

[0099] [Table 2]

[0100] [Table 3]

[0101] Table 4 shows the catalytic performance using the CSTR test protocol set forth above for catalysts 1 through 10. All ten catalysts are of the present invention, and each achieves selectivity of 88.4% or greater and activity of ΔEO=1.23 vol.% or greater.

[0102] [Table 4]

[0103] Catalysts 11-45 were prepared using the incipient wetness method presented above, and the performance of catalysts 11-45 was evaluated in the HPRAM reactor following the plug flow reactor testing protocol. Target promoter concentrations are shown in Table 5. Performance results are shown in Table 6 and Figure 1. As shown in Figure 1, the selectivities are in the range of 87.1-91.6% and 84.3-86.4% for the inventive and comparative catalysts, respectively.

[0104] [Table 5]

[0105] [Table 6]

[0106] [Table 7]

[0107] [Table 8]

[0108] Catalyst 46 50.09 g of support G are converted into "catalyst 46" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.04 g silver solution (25.69 wt% Ag) 0.6013 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.8065 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.4623g of CsOH solution (111.9mg of Cs / g of solution) 2.2177 g of LiOCOCH3 solution (12.00 mg of Li / g solution) 0.4091 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.7992 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 5.8594 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 21.02 wt. % Ag, as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0109] Catalyst 47 50.21 g of support G are converted into "catalyst 47" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.35 g silver solution (27.62 wt% Ag) 0.0000g Mn(NO3)2 solution (38.00mg Mn / g solution) 0.0000g of (NH4)2H2(EDTA) solution (401.0mg of EDTA / g solution) 1.6822g of CsOH solution (111.9mg of Cs / g of solution) 2.5511 g of LiOCOCH3 solution (12.00 mg of Li / g solution) 0.4704 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.9195 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 6.7391 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 20.54 wt. % Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0110] Catalyst 48 50.08 g of support G are converted into "catalyst 48" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.20 g of silver solution (25.69 wt% Ag) 1.5226 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 2.0444 g of (NH4)2H2(EDTA) solution (401.0 mg EDTA / g solution) 1.5497g of CsOH solution (111.9mg of Cs / g of solution) 2.3497 g of LiOCOCH3 solution (12.00 mg of Li / g solution) 0.4337g of NaOCOCH3 solution (50.00mg of Na / g solution) 0.8471 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 6.2084 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 19.69 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0111] Catalyst 49 50.16 g of support G are converted into "catalyst 49" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.25 g silver solution (25.69 wt% Ag) 1.0960 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 1.4711 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.5730 g of CsOH solution (111.9 mg of Cs / g of solution) 2.3847g of LiOCOCH3 solution (12.00mg of Li / g of solution) 0.4403 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.8597 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 6.3016 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 21.02 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0112] Catalyst 50 50.23 g of support G are converted into "catalyst 50" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.01 g silver solution (25.69 wt% Ag) 0.3035 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.4073 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.4903 g of CsOH solution (111.9 mg of Cs / g of solution) 2.2595 g of LiOCOCH3 solution (12.00 mg of Li / g solution) 0.4168 g of NaOCOCH3 solution (50.00 mg of Na / g solution). 0.8144 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 5.9709 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 22.06 wt. % Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0113] Catalyst 51 50.10 g of support G are converted into "catalyst 51" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.16 g silver solution (25.69 wt% Ag) 0.6126 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.8222 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.4901g of CsOH solution (111.9mg of Cs / g of solution) 0.0000g LiOCOCH3 solution (12.00mg Li / g solution) 0.4169 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.8144 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 5.9702 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 21.41 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0114] Catalyst 52 50.41 g of support G are converted into "catalyst 52" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.00 g of silver solution (25.69 wt% Ag) 0.0000g Mn(NO3)2 solution (38.00mg Mn / g solution) 0.0000g of (NH4)2H2(EDTA) solution (401.0mg of EDTA / g solution) 1.5414g of CsOH solution (111.9mg of Cs / g of solution) 0.0000g LiOCOCH3 solution (12.00mg Li / g solution) 0.4314 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.8422 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 6.1754 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 21.88 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0115] Catalyst 53 50.35 g of support G are converted into "catalyst 53" according to the vacuum impregnation method presented above. The following amounts are used to prepare the impregnation solution: 165.18 g silver solution (25.69 wt% Ag) 0.6335 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.8507 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.5416g of CsOH solution (111.9mg of Cs / g of solution) 0.0000g LiOCOCH3 solution (12.00mg Li / g solution) 0.6742 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 1.1044 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 6.1766 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 20.16 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0116] Catalyst 54 50.34 g of support H is converted to "Catalyst 54" according to the vacuum impregnation method presented above. For the preparation of this catalyst, a silver impregnation solution was prepared by diluting the silver impregnation solution used for catalyst 50 with deionized water. The following amounts are used to generate the impregnation solution: 165.10 g of silver solution (18.00 wt% Ag) 0.3558 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.4771 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 0.8036g of CsOH solution (111.9mg of Cs / g of solution) 0.4207g of LiOCOCH3 solution (12.00mg of Li / g solution) 0.1264g of NaOCOCH3 solution (50.00mg of Na / g solution) 0.5409 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 1.9589 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 16.18 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0117] Catalyst 55 50.13 g of support H is converted to "Catalyst 55" according to the vacuum impregnation method presented above. For the preparation of this catalyst, a silver impregnation solution was prepared by diluting the silver impregnation solution used for catalyst 50 with deionized water. The following amounts are used to generate the impregnation solution: 165.10 g of silver solution (20.18 wt% Ag) 0.3576 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.4798 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 0.8080g of CsOH solution (111.9mg of Cs / g of solution) 0.4228g LiOCOCH3 solution (12.00mg Li / g solution) 0.1263 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.5438 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 1.9690 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 18.36 wt. % Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

[0118] Catalyst 56 50.35 g of support H is converted to "Catalyst 56" according to the vacuum impregnation method presented above. For the preparation of this catalyst, a silver impregnation solution was prepared by diluting the silver impregnation solution used for catalyst 50 with deionized water. The following amounts are used to generate the impregnation solution: 164.90 g of silver solution (18.00 wt.% Ag) 0.5464 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.7333 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.4664g of CsOH solution (111.9mg of Cs / g of solution) 2.2263 g of LiOCOCH3 solution (12.00 mg of Li / g solution) 0.4117 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.8033 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 5.8757 g of NH4ReO4 solution (32.20 g Re / g solution). The resulting catalyst contains 15.79 wt% Ag as determined gravimetrically (i.e., 16 wt% when rounded to the nearest whole number). Target promoter concentrations for all promoters are listed in Table 7.

[0119] Catalyst 57 50.22 g of support H is converted to "Catalyst 57" according to the vacuum impregnation method presented above. For the preparation of this catalyst, a silver impregnation solution was prepared by diluting the silver impregnation solution used for catalyst 50 with deionized water. The following amounts are used to generate the impregnation solution: 165.05 g silver solution (20.18 wt% Ag) 0.5712 g of Mn(NO3)2 solution (38.00 mg Mn / g solution) 0.7661 g of (NH4)2H2(EDTA) solution (401.0 mg of EDTA / g solution) 1.5326g of CsOH solution (111.9mg of Cs / g of solution) 2.3264 g of LiOCOCH3 solution (12.00 mg of Li / g solution) 0.4297 g of NaOCOCH3 solution (50.00 mg of Na / g solution) 0.8394 g of (NH4)2SO4 solution (40.00 mg of SO4 / g solution) 6.1408 g of NH4ReO4 solution (32.20 g Re / g solution). The produced catalyst contains 17.92 wt% Ag as determined gravimetrically. Target promoter concentrations for all promoters are listed in Table 7.

Claims

1. A supported silver catalyst prepared on an alumina-containing support, wherein the support contains more than about 80 weight percent α-alumina and less than about 30 parts per million by weight of acid-leachable alkali metal, and the weight percent of the alumina and the concentration of the acid-leachable alkali metal are calculated based on the weight of the support, and the acid-leachable alkali metal is selected from lithium, sodium, potassium, and mixtures thereof, and the support has deposited thereon, (A) silver in an amount of 16 to 25 weight percent of the catalyst; and (B) a solid promoter package containing cesium, sodium, sulfate, rhenium, and optionally lithium, wherein the amounts of these promoters are expressed in millimoles of promoter per kilogram of catalyst, and the amounts of these promoters in the solid promoter package deposited on the catalyst are such that C Ｃｓ C / Q is in the range of 3.1 to 8.7 mmol / kg catalyst, C Ｎａ C / Q is in the range of 0.5 to 7.5 mmol / kg catalyst, C Ｓ C / Q is in the range of 0.3 to 3.2 mmol / kg catalyst, C Ｒｅ C / Q is in the range of 2.4 to 6.9 mmol / kg catalyst, C Ｌｉ / Q is in the range of 0 to 35 mmol / kg catalyst, F1 / Q is in the range of 0.3 to 5.2 mmol / kg catalyst, F2 / Q is in the range of -5.1 to 6.3 mmol / kg catalyst, wherein Q is a dimensionless scaling factor equal to the surface area of the alumina-containing support before deposition of silver and the promoter, expressed in units of square meters per gram divided by square meters per gram, wherein F1 and F2 are defined by the following equations, F1 = C Ｃｓ + 0.032·C Ｌｉ + 0.47·C Ｎａ −(0.72·C Ｓ + 0.94·C Ｒｅ ) F2 = C Ｃｓ -0.24 · C Ｌｉ -0.27 · C Ｎａ +0.3 · C Ｓ , wherein C Ｃｓ , C Ｌｉ , C Ｎａ , C Ｓ , and C Ｒｅ are the amounts of cesium, lithium, sodium, sulfate, and rhenium respectively deposited on the carrier, represented in mmol units of the promoter per 1 kg of the catalyst, the catalyst.

2. The catalyst according to claim 1, wherein the support further has manganese in an amount of 20 to 300 weight ppm of the catalyst deposited thereon.

3. The amount of cesium deposited on the catalyst is such that C Ｃｓ / Q is in the range of 4.2 to 7.8 mmol / kg of catalyst, the catalyst according to claim 1 or 2.

4. The amount of lithium deposited on the catalyst is such that C Ｌｉ / Q is in the range of 6 to 30 mmol / kg of catalyst, the catalyst according to claim 1 or 2.

5. The amount of sodium deposited on the catalyst is such that C Ｎａ / Q is in the range of 1.2 to 7.5 mmol / kg of catalyst, the catalyst according to claim 1 or 2.

6. The amount of rhenium deposited on the catalyst is such that C Ｒｅ / Q is in the range of 3.0 to 6.8 mmol / kg catalyst, the catalyst according to claim 1 or 2.

7. The catalyst according to claim 1 or 2, wherein the amount of the promoter deposited on the catalyst is such that F1 / Q is in the range of 1.5 to 4.1 mmol / kg catalyst.

8. The catalyst according to claim 7, wherein the amount of the promoter deposited on the catalyst is such that F1 / Q is in the range of 1.9 to 3.7 mmol / kg catalyst.

9. The catalyst according to claim 1 or 2, wherein the amount of the promoter deposited on the catalyst is such that F2 / Q is in the range of -2.5 to 3.5 mmol / kg catalyst.

10. The catalyst according to claim 9, wherein the amount of the promoter deposited on the catalyst is such that F2 / Q is in the range of -1.8 to 2.7 mmol / kg catalyst.

11. The amounts of the promoters in the solid promoter package deposited on the catalyst are C Ｃｓ / Q is in the range of 4.7 to 7.3 mmol / kg catalyst, C Ｌｉ C / Q is in the range of 10 to 26 mmol / kg catalyst, C Ｎａ C / Q is in the range of 2.5 to 7.5 mmol / kg catalyst, C Ｒｅ The catalyst according to claim 1 or 2, wherein C / Q is in the range of 3.3 to 6.7 mmol / kg catalyst, F1 / Q is in the range of 1.9 to 3.7 mmol / kg catalyst, and F2 / Q is in the range of -1.8 to 2.7 mmol / kg catalyst, in such amounts.

12. The catalyst according to claim 1 or 2, wherein the catalyst is prepared using a firing step carried out at a temperature within the range of 480 to 550 °C.

13. The catalyst according to claim 12, wherein the firing is carried out on a firing belt and the catalyst is present for a duration of 5 minutes or less within a hot zone at a temperature within the range of 480 to 550 °C.

14. The alumina-containing carrier has a surface area in the range of 0.7 to 1.5 m ２ / g, and the catalyst according to any one of claims 1 or 2.

15. Use of the catalyst according to claim 1 or 2 in the production of ethylene oxide.

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