Process for the production of ethylene oxide

Abstract

A process for the epoxidation of ethylene, the process comprising: contacting an inlet feed gas comprising ethylene, oxygen and one or more reaction modifiers consisting of organic chlorides with an epoxidation catalyst comprising a support and having silver, rhenium promoters and one or more alkali metal promoters deposited on the support; wherein the inlet feed gas has a total catalyst chloriding effectiveness value (Cleff) represented by formula (I): wherein [MC], [EC], [EDC] and [VC] are the concentrations in ppmv of chloromethane (MC), chloroethane (EC), dichloroethane (EDC) and chloroethylene (VC), respectively, and [CH4], [C2H6] and [C2H4] are the concentrations in mole percent of methane, ethane and ethylene, respectively, in the inlet feed gas; wherein the process is operated at a reaction temperature having a value T1 and with the inlet feed gas having an optimal total catalyst chloriding effectiveness value Cl 3 efficacy value Cl eff1 1, to produce ethylene oxide, wherein the ethylene oxide production parameter is a value EO1; and characterized in that the support is a fluoride mineralized alpha-alumina support, and subsequently operating the process so that at a cumulative ethylene oxide production cumEO x , wherein cumEO x is at least 0.6 kton ethylene oxide / m 3 of catalyst greater than cumEO1, the reaction temperature 5 has an increased value Tx to maintain the ethylene oxide production parameter at a value EO1, while controlling the optimal total catalyst chloriding effectiveness value Cl effx of the inlet feed gas so that the ratio Cl effx / C leff1 is in the range of 0.8 to 1.2.

Description

[0001] This invention relates to a method for producing ethylene oxide. Background Technology

[0002] Ethylene oxide (EO) is a valuable raw material known as a general chemical intermediate in the production of a wide variety of chemicals and products. For example, ethylene oxide is commonly used to produce ethylene glycol, which is used in many different applications and can be found in a variety of products, including automotive engine antifreeze, hydraulic brake fluid, resins, fibers, solvents, paints, plastics, films, household and industrial cleaners, pharmaceutical preparations, and personal care products such as cosmetics and shampoos.

[0003] In the commercial production of ethylene oxide, ethylene reacts with oxygen in an epoxidation reactor in the presence of an epoxidation catalyst to produce a gas stream containing ethylene oxide at the reactor outlet. In addition to ethylene oxide, the reactor outlet stream typically contains unreacted ethylene, unreacted oxygen, reaction modifiers (e.g., organochlorides), dilution gases (e.g., nitrogen, methane, or combinations thereof), various byproducts of the epoxidation reaction (e.g., carbon dioxide and water), and various impurities (e.g., aldehydes, acidic impurities, argon, ethane, etc.).

[0004] In the next stage, ethylene oxide is recovered from the reactor effluent stream, typically by supplying the reactor effluent stream to an ethylene oxide separation system, where the produced ethylene oxide is separated from most other gaseous components by contact with a recycle solvent (often referred to as a "lean absorbent").

[0005] The resulting ethylene oxide is typically further reacted, for example, via catalytic or non-catalytic hydrolysis to provide diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, etc.). Generally, most of the remaining gaseous components in the ethylene oxide separation system (e.g., unreacted ethylene, unreacted oxygen, reaction modifiers, dilution gases, etc.) are removed from the epoxidation reactor as an overhead gas stream. At least a portion of this overhead gas stream is typically recycled back to the epoxidation reactor via a recirculation gas loop to minimize waste and / or increase savings, as the use of the recirculation gas stream reduces the amount of fresh “replenishment” feed (e.g., ethylene, oxygen, etc.) that needs to be supplied to the epoxidation reactor. Optionally, at least a portion of the recirculation gas stream may be supplied to one or more separation and / or purification systems, such as a carbon dioxide separation system, before being supplied to the epoxidation reactor.

[0006] Ethylene oxide is formed by reacting ethylene with oxygen in the presence of a silver-based ethylene epoxidation catalyst. Catalyst performance can be evaluated based on the selectivity, activity, and stability of the operation. The selectivity of an ethylene epoxidation catalyst, also known as “efficiency,” refers to the catalyst’s ability to convert ethylene to the desired reaction product ethylene oxide relative to competing byproducts (e.g., CO2 and H2O), and is typically expressed as a percentage of the number of moles of ethylene oxide produced per mole of ethylene reacted.

[0007] Stability refers to how the selectivity and / or activity of the method change during the use of catalyst loading, i.e., when more ethylene oxide is produced.

[0008] Various methods for improving the performance of ethylene epoxidation catalysts have been investigated, including enhancing selectivity, activity, and stability. For example, modern “high-selectivity” silver-based ethylene epoxidation catalysts may include a rhenium promoter in addition to silver, and optionally one or more other promoters, such as alkali metals (e.g., cesium, lithium, etc.), alkaline earth metals (e.g., magnesium), transition metals (e.g., tungsten), and group nonmetals (e.g., sulfur), are disclosed in, for example, US 4761394 A and US 4766105 A.

[0009] Selectivity largely determines the economic attractiveness of epoxidation processes. For example, a one percent increase in selectivity in an epoxidation process can significantly reduce the annual operating costs of a large-scale ethylene oxide plant. Furthermore, the longer activity and selectivity can remain at acceptable levels, the longer the catalyst charge can remain in the reactor and the greater the product yield. Even modest improvements in selectivity, activity, and the long-term maintenance of selectivity and activity have yielded substantial benefits in terms of process efficiency.

[0010] In addition to improvements in catalyst formulation, reaction modifiers have been discovered that can be added to the feed to enhance selectivity (see, for example, EP 0352850 A1). These reaction modifiers inhibit the oxidation of undesirable ethylene or ethylene oxide to carbon dioxide and water via mechanisms that have not been previously explained, relative to the desired ethylene oxide formation. Suitable reaction modifiers are, for example, organohalides.

[0011] EP 0352850 A1 discloses that highly selective silver catalysts containing rhenium tend to exhibit relatively steep selectivity curves to modifiers. Specifically, for highly selective silver catalysts containing rhenium, the selectivity varies significantly with relatively small changes in the amount of the modifier, and the selectivity exhibits a significant maximum, or optimum, at a given amount of modifier. This is illustrated in EP 0352850 A1 (see [reference needed]). Figure 3 ).

[0012] It is also well known in the field of ethylene epoxidation that when using highly selective silver epoxidation catalysts, i.e. catalysts containing silver, rhenium promoters and optionally one or more other promoters on a solid refractory support, the catalyst activity decreases as the catalyst ages, requiring the reaction temperature to be increased over time in order to maintain ethylene oxide production at the desired level.

[0013] Furthermore, the selectivity profile and, more particularly, the amount of the reaction modifier with the highest selectivity tend to vary with reaction temperature, and thus vary during catalyst lifetime.

[0014] Therefore, when such highly selective silver epoxidation catalysts are used in combination with reaction modifiers, the selectivity can vary undesirably with changes in reaction temperature and catalyst lifetime. In other words, when the reaction temperature changes, for example to compensate for a decrease in catalyst activity, it is necessary to maintain optimal reaction conditions for maximizing the selectivity for ethylene oxide production.

[0015] Since the development of modern silver-based ethylene epoxidation catalysts in US 4761394 A and US 4766105 A, there has been continuous teaching in this field over the past 30 years (e.g., in EP 0352850A1, WO 03 / 044003A1, WO2010 / 123844 A1, WO 2010 / 123842 A1 and WO 2015 / 100209 A1) that when using such highly selective silver epoxidation catalysts, as the catalyst ages, it is necessary to increase the concentration of reaction modifiers (especially organochlorides) in the feed gas over time to maintain maximum selectivity.

[0016] Therefore, when applying reactive modifiers, the general guideline is to select a concentration in the feed that maximizes selectivity. In the past, during epoxidation processes, the optimal reactive modifier concentration for maximum selectivity was often determined through iterative trial procedures—gradually varying the reactive modifier supply rate and monitoring its effect on selectivity. However, such procedures are cumbersome and would cause the process to operate under uneconomical conditions for a period. Furthermore, when the feed composition changes, the iterative trial procedure needs to be repeated to adjust the reactive modifier concentration to the new reaction conditions.

[0017] However, given the generally accepted teaching that the optimal concentration of the chlorine reaction modifier varies with temperature when operating such catalysts, various alternative methods and mathematical relationships have been described in the art to more effectively determine the optimal concentration of the chlorine reaction modifier at a given temperature and adjust the feed gas accordingly without relying on tedious trial-and-error procedures.

[0018] The methods described in this art typically focus on determining the total chloride reaction modifier concentration (Min WO 2015 / 100209A1) or the total catalyst chlorination efficiency value (Q or Z* in WO 03 / 044003A1, WO 2010 / 123844 A1 and WO 2010 / 123842 A1) based on a list of organochlorides and hydrocarbons present in the feed gas.

[0019] As the optimal chloride concentration in the feed gas moves to higher concentrations over time and the reaction temperature increases accordingly due to catalyst aging, it should be understood that the effective teaching of the prior art is that when using an epoxidation catalyst containing silver, rhenium, and one or more alkali metal promoters on a solid refractory support, the value of the total catalytic chlorination efficiency will also increase over time.

[0020] It is recognized in the art that continuously determining the optimal chloride concentration (whether by iterative experimentation or by calculation) and adjusting the chloride reaction modifier concentration during the operation of industrial ethylene epoxidation processes is difficult and tedious.

[0021] Furthermore, as epoxidation catalysts containing silver, rhenium, and one or more alkali metal promoters age and the optimal chloride concentration shifts to higher levels, greater demands are placed on downstream purification equipment to control the increased chloride content in the reactor system. In other words, as the chloride concentration in the feed gas increases over time, downstream purification equipment will encounter increased amounts of byproduct organochlorides and acidic compounds. These acidic compounds require the addition of basic compounds such as sodium hydroxide to maintain a suitable pH in the aqueous portion of the reactor system.

[0022] Therefore, despite improvements already achieved in the field of ethylene epoxidation, further improvements to the performance of ethylene epoxidation catalysts are desired. In particular, there is a strong need to find a simplified method for operating industrial ethylene epoxidation processes at the desired ethylene oxide production levels. This method should not only avoid the need for continuous monitoring and optimization of chloride reaction modifier concentrations during operation, but also avoid the need to increase the concentration of chlorination reaction modifiers or the total catalyst chlorination efficiency over time as the epoxidation catalyst ages.

[0023] In this invention, it has been surprisingly discovered that there exist specific epoxidation catalysts comprising silver, rhenium, and one or more alkali metal promoters, which do not require the chloride concentration in the feed gas or the optimal total catalyst chlorination efficiency to increase with catalyst aging in response to rising reaction temperature in order to maintain maximum selectivity at the desired ethylene oxide production level. Summary of the Invention

[0024] This invention provides a method for ethylene epoxidation, the method comprising:

[0025] An inlet feed gas containing ethylene, oxygen, and one or more reaction modifiers composed of organochlorides is contacted with an epoxidation catalyst containing a support and having silver, rhenium, and one or more alkali metal promoters deposited on the support; wherein the inlet feed gas has a total catalytic chlorination efficiency value (Cl) expressed by the following formula. eff ):-

[0026]

[0027] Wherein [MC], [EC], [EDC] and [VC] are the concentrations of chloromethane (MC), chloroethane (EC), dichloroethane (EDC) and vinyl chloride (VC) in ppmv, respectively, and [CH4], [C2H6] and [C2H4] are the concentrations of methane, ethane and ethylene in the inlet feed gas in molar percentage, respectively;

[0028] Among them, at least 0.2 kton ethylene oxide / m 3 The cumulative ethylene oxide yield of the catalyst, cumEO1, is obtained at a reaction temperature having a value T1 and using Cl with the optimal total catalyst chlorination efficiency. eff1 The inlet feed gas is operated to produce ethylene oxide, wherein the ethylene oxide production parameter is value EO1; and is characterized in that...

[0029] The support is a fluoride-mineralized α-alumina support, and the method is subsequently operated such that the cumulative ethylene oxide production (cumEO) is increased. x At, cumEO x It is at least 0.6 kton ethylene oxide / m³ greater than cumEO1. 3 The catalyst, wherein the reaction temperature has an increased value Tx to maintain the ethylene oxide production parameters at a value EO1, while controlling the optimal total catalyst chlorination efficiency Cl of the inlet feed gas. effx , making Cl effx / Cl eff1 The ratio is in the range of 0.8 to 1.2. Attached Figure Description

[0030] Some specific example embodiments of this disclosure can be understood by referring in part to the following description and figures.

[0031] Figure 1 A schematic diagram illustrating an exemplary ethylene epoxidation process.

[0032] Figure 2 A graph showing the activity distribution of catalysts A through G tested under condition 1.

[0033] Figure 3 To depict catalysts A to G in Figure 2 The optimal total chlorination efficiency (Cl) value during the production cycle is shown. eff (The image is shown.)

[0034] Figure 4 To depict each of catalysts A through G in Figure 2 The optimal total chlorination efficiency (Cl) value at any time during the production cycle is shown. effx ) and at 0.2kton / m 3 Optimal total chlorination efficiency (C) for cumulative ethylene oxide production leff1 A graph showing the ratio of ).

[0035] Figure 5 A graph showing the activity distribution of catalysts A, B, E, H, and I tested under condition 2.

[0036] Figure 6 To depict catalysts A, B, E, H, and I in Figure 5 The optimal total chlorination efficiency (C) value during the production cycle is shown. leff (The image is shown.)

[0037] Figure 7 To depict the properties of each of catalysts A, B, E, H, and I in Figure 5 The optimal total chlorination efficiency (Cl) value at any time during the production cycle is shown. effx ) and at 0.2kton / m 3 Optimal total chlorination efficiency (C) for cumulative ethylene oxide production leff1 A graph showing the ratio of ).

[0038] Figure 8 To describe the optimal total chlorination efficiency (Cl) of catalysts A and B at any time, compared to multiple runs of catalyst J within the production cycle shown. effx ) and at 0.2kton / m 3 The optimal total chlorination efficiency (C) at the cumulative ethylene oxide production rate leff1 A graph showing the ratio of ).

[0039] While this disclosure allows for various modifications and alternatives, specific example implementations have been shown in the figures and described in more detail herein.

[0040] However, it should be understood that the description of the specific exemplary embodiments is not intended to limit the invention to the particular forms disclosed, but rather, this disclosure will cover in part all modifications and equivalents shown by the appended claims. Detailed Implementation

[0041] To facilitate understanding of this disclosure, it is useful to define certain terms related to epoxidation reactions and the performance of epoxidation catalysts.

[0042] As used herein, “ethylene oxide production parameters” are measures of the extent to which ethylene oxide is produced during a process used for ethylene epoxidation. These production parameters can be selected from a group consisting of the concentration of ethylene oxide in the product gas, the ethylene oxide production rate, and the ethylene oxide production rate / catalyst volume (also known as the operating rate (WR)).

[0043] The “activity” of an epoxidation catalyst is typically expressed as the reaction temperature required to maintain given ethylene oxide production parameters. Generally, the activity of an epoxidation catalyst is a function of both the total number of catalytically active sites present on the surface of the catalyst and the reaction rate at each site. Therefore, if the number of catalytically active sites on the surface of the epoxidation catalyst decreases and / or if the reaction rate at one or more active sites decreases (e.g., due to local poisoning), the catalyst activity will decrease (and therefore, the reaction temperature required to maintain given ethylene oxide production parameters will increase). The total number of active sites can be reduced in several ways, for example, by sintering the catalytically active particles (i.e., silver particles), which results in an increase in the size of the silver particles and a corresponding decrease in the surface area of ​​the silver. The number of active sites can also be reduced in the presence of excess of other unwanted elements such as alkali metals or sulfur, which can enter the reactor as impurities or poisons and deposit on the catalyst, through the reaction with chlorides in the inlet feed gas to form silver chloride compounds. Silver chloride compounds are inactive for the epoxidation reaction. In addition, activity may decrease due to catalyst poisoning, for example, due to exposure of the epoxidation catalyst to poisons such as sulfur, iodine, silicon and phosphorus.

[0044] In many cases, ethylene oxide production parameters are described using "operating rate," which refers to the amount of ethylene oxide produced per hour per unit volume of catalyst in the epoxidation reactor (e.g., kg or moles of ethylene oxide / hour / m³). 3 (Catalyst). As those skilled in the art will understand, under a given set of conditions, an increase in catalyst activity is reflected by the lower reaction temperature required to maintain a given operating rate under those conditions. Therefore, an epoxidation catalyst with “higher activity” compared to another epoxidation catalyst is one that uses a lower reaction temperature at a given operating rate under a given set of conditions.

[0045] Alternatively, the "activity" of an epoxidation catalyst can be expressed as the molar percentage of ethylene oxide in the reactor effluent relative to the molar percentage of ethylene oxide in the inlet feed gas (the molar percentage of ethylene oxide in the inlet feed gas is typically, but not necessarily, close to zero), while the reaction temperature remains substantially constant. Therefore, in this case, an epoxidation catalyst with "higher activity" compared to another epoxidation catalyst is one that produces more ethylene oxide (i.e., has a higher operating rate) at a given reaction temperature and under a given set of conditions.

[0046] As used herein, the “selectivity” of an epoxidation catalyst, also known as “efficiency,” refers to the ability of an epoxidation catalyst to convert ethylene into the desired reaction product ethylene oxide relative to competing byproducts (e.g., CO2 and H2O), and is typically expressed as a percentage of the number of moles of ethylene oxide produced per mole of ethylene consumed in the reactor. As those skilled in the art will understand, an epoxidation catalyst with “higher selectivity” compared to another epoxidation catalyst is one that provides a greater number of moles of ethylene oxide produced per mole of ethylene consumed under a given set of conditions.

[0047] As used herein, “deactivation” refers to the permanent reduction or loss of catalytic activity and / or selectivity. During the epoxidation process, as epoxidation catalysts are used, they eventually begin to “age” and their catalytic performance gradually deteriorates (e.g., due to reduced catalyst activity, such as silver sintering). Typically, the average lifetime of modern epoxidation catalysts is about two to five years, depending on factors such as the type of epoxidation catalyst, reaction temperature, operating conditions, exposure to catalyst poisons, etc. Typically, when catalytic activity begins to decline, the reaction temperature is increased to compensate for and maintain a constant level of ethylene oxide yield, as measured by ethylene oxide production parameters (e.g., to maintain the desired operating rate). However, such increases in reaction temperature often reduce catalyst selectivity and increase the rate of catalyst deactivation (i.e., accelerate catalyst aging). The phenomenon of decreased selectivity is complex and depends on many factors, such as catalyst activity, operating conditions, operating rate, catalyst lifetime, presence of poisons, etc. Generally, the “stability” of an epoxidation catalyst is inversely proportional to the rate of catalyst deactivation and is related to the length of time that catalyst performance and productivity can remain at acceptable levels before the catalyst needs to be replaced with a fresh one. The term "stability" can be applied to both the decrease in activity and the decrease in selectivity over time. As will be readily understood, from an economic perspective, improvements in catalyst stability (activity stability and / or selectivity stability) are highly desirable, as epoxidation catalysts represent a significant expense for the plant, as do the production losses due to plant downtime when the catalyst is replaced.

[0048] As used herein, "end of catalyst life" refers to the point at which the catalyst has achieved its final cumulative EO production before being removed from the reactor and optionally replaced with a fresh catalyst charge. That is, the catalyst is started and running, producing EO during its operation. At a later point in time, the catalyst operation is stopped, and the catalyst is removed from the reactor and replaced. The final cumulative EO production is the total amount of EO produced from the catalyst's start-up to its removal from the reactor.

[0049] As described below, normal catalyst lifetime depends on many factors. Typically, catalyst lifetime is at least 1.5 kton / m³. 3 Cumulative EO production can be extended to 4.0 kton / m³. 3 Or more cumulative EO production. The decision of when to replace the catalyst for fresh feed can depend on many factors, including key catalyst activity, catalyst selectivity and productivity, turnaround schedule, statutory inspections, major maintenance shutdowns, etc.

[0050] As discussed above, the prior art teaches that when epoxidation catalysts containing silver, rhenium and one or more alkali metal promoters experience aging-related activity decline, it is necessary to increase the reaction temperature to maintain ethylene oxide production parameters, while also increasing the concentration of organochlorine reaction modifiers in the feed gas to maintain maximum selectivity.

[0051] In this invention, it has been surprisingly discovered that there are specific epoxidation catalysts containing silver, rhenium, and one or more alkali metal co-catalysts that do not require careful control of the concentration of organochloride reaction modifiers in the feed gas to maintain maximum selectivity as the catalyst ages.

[0052] Therefore, the present invention greatly simplifies the industrial operation of the ethylene epoxidation process for equipment operators, because the maximum selectivity performance at constant values ​​of ethylene oxide production parameters can be advantageously achieved by keeping the concentration of the organochlorine reaction modifier in the feed gas constant or within a narrow concentration range for a given feed gas.

[0053] In cases where the feed gas undergoes minor variations in the concentration of other feed gas components such as ethylene or hydrocarbons (e.g., ethane), then according to the invention, when using an epoxidation catalyst comprising a fluoride-mineralized α-alumina support and having silver, rhenium, and alkali metal promoters deposited thereon, EO plant operators will find operation greatly simplified, as EO plant operators no longer need to optimize chloride concentrations and can simply ensure that the total catalyst chlorination efficiency remains within a narrow range throughout catalyst operation.

[0054] Epoxidation process

[0055] The epoxidation process of the present invention can be carried out in a variety of ways known in the art; however, a continuous gas-phase method is preferred. Similarly, the epoxidation process can be carried out in any known epoxidation reactor (e.g., any reactor vessel used to react ethylene and oxygen), such as a fixed-bed reactor (e.g., a fixed-bed tubular reactor), a continuous stirred-tank reactor (CSTR), a fluidized-bed reactor, etc. Furthermore, multiple epoxidation reactors can be used in parallel or in series.

[0056] A commercial example of a suitable epoxidation reactor is a vertical shell-and-tube heat exchanger, in which the shell contains a coolant (e.g., a heat transfer fluid such as tetrahydronaphthalene, water, etc.) to regulate the temperature of the epoxidation reactor, and multiple tubes are substantially parallel, slender tubes containing an epoxidation catalyst. While the size and number of tubes can vary from reactor to reactor, typical tubes used in commercial reactors can have lengths of 3 to 25 meters, 5 to 20 meters, or 6 to 15 meters. Similarly, reactor tubes can have inner tube diameters of 5 to 80 millimeters, 10 to 75 millimeters, or 20 to 60 millimeters. The number of tubes present in an epoxidation reactor can vary widely and can range in the thousands, for example, up to 22,000, or 1,000 to 11,000, or 1,500 to 18,500.

[0057] A portion of an epoxidation reactor containing an epoxidation catalyst (e.g., reactor tubes) is typically referred to as a "catalyst bed." The amount of epoxidation catalyst in the catalyst bed, the height of the catalyst bed, and the packing density of the epoxidation catalyst within the catalyst bed (i.e., the "tube packing density") can vary over a wide range, depending on, for example, the size and number of tubes present within the epoxidation reactor, as well as the size and shape of the epoxidation catalyst. However, a typical range for tube packing density can be 400 kg / m³. 3 Up to 1500 kg / m 3 Similarly, the typical range for catalyst bed height can be 50% to 100% of the reactor tube length. In those embodiments where the catalyst bed height is less than 100% of the reactor tube length, the remaining portion of the tube may be empty or optionally contain particles of non-catalytic or inert material.

[0058] Figure 1 This is a schematic diagram illustrating an exemplary ethylene epoxidation process. Ethylene, oxygen, dilution gas, and reactant modifiers are present in... 1 The gas is supplied to the recirculated gas stream. 14 To limit the supply to the epoxidation reactor 4 Entrance 3 Inlet feed gas 2 In the epoxidation reactor 4Inside, ethylene and oxygen react in the presence of an epoxidation catalyst. The reactor outlet stream contains ethylene oxide, unreacted ethylene, unreacted oxygen, reaction modifiers, dilution gases, various byproducts of the epoxidation reaction (e.g., carbon dioxide and water), and various impurities. 5 From epoxidation reactor 4 Extracted from and supplied to the ethylene oxide separation system 6 From the ethylene oxide separation system 6 At least a portion of the net product flow 7 Further reactions can be carried out, for example, via catalytic or non-catalytic hydrolysis to provide diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, etc.).

[0059] In ethylene oxide separation system 6 Most of the unabsorbed gaseous components (e.g., unreacted ethylene, unreacted oxygen, reactive modifiers, dilution gases, etc.) are carried over as the overhead gas stream. 8 It is drawn from and supplied to the recirculating gas compressor. 9 Then at least a portion of the airflow at the top of the tower can be... 8 Supply to carbon dioxide separation system 10 Meanwhile, the remaining portion (if any) flows through a bypass. 11 Bypassing the carbon dioxide separation system. In the carbon dioxide separation system... 10 In the process, carbon dioxide is removed and passed through a carbon dioxide stream. 12 Exhausted, while the gas flow at the top of the tower... 13 With bypass flow 11 Combined to form a recirculated gas flow 14 As mentioned earlier, the recirculated gas flow 14 Combined with "supplementary" ethylene, oxygen, dilution gas, and reaction modifier to form the inlet feed gas. 2 .

[0060] The epoxidation process described in this article is not limited to any specific reactor or flow configuration, and Figure 1 The examples described herein are merely illustrative. Furthermore, the order in which various feed components are introduced into the process, their respective introduction points, and flow connections can be varied. Figure 1 The descriptions differ from those in the text.

[0061] Inlet feed gas composition

[0062] According to the epoxidation process described herein, the inlet feed gas contains ethylene, oxygen, and one or more reaction modifiers composed of organochlorides. Optionally, the inlet feed gas may also contain non-chlorinated hydrocarbons, such as ethane, carbon dioxide, diluent gases, water vapor, and combinations thereof.

[0063] As used herein, the term "inlet feed gas" should be understood to refer to the total amount of gas flow at the inlet of the epoxidation reactor. Therefore, as those skilled in the art will understand, the inlet feed gas typically consists of a combination of one or more gas flows, such as an ethylene flow, an oxygen flow, a reaction modifier injection flow, a recirculated gas flow, etc.

[0064] Ethylene can be present in the inlet feed gas at concentrations that vary over a wide range. However, ethylene is typically present in the inlet feed gas at a concentration of at least 5 mol% relative to the total inlet feed gas, or at least 8 mol%, or at least 10 mol%, or at least 12 mol%, or at least 14 mol%, or at least 20 mol%, or at least 25 mol% on the same basis. Similarly, ethylene is typically present in the inlet feed gas at a concentration of up to 65 mol%, or up to 60 mol%, or up to 55 mol%, or up to 50 mol%, or up to 48 mol% on the same basis. In some embodiments, ethylene can be present in the inlet feed gas at a concentration of 5 mol% to 60 mol% relative to the total inlet feed gas, or 10 mol% to 50 mol%, or 12 mol% to 48 mol% on the same basis.

[0065] In addition to ethylene, the inlet feed gas also contains oxygen, which can be provided as pure oxygen or air. See "Kirk-Othmer Encyclopedia of Chemical Technology", 3rd edition, Vol. 9, 1980, pp. 445-447. In air-based processes, air or oxygen-enriched air is used, while in oxygen-based processes, high-purity (at least 95 mol%) or very high-purity (at least 99.5 mol%) oxygen is used. For a further description of oxygen-based epoxidation processes, refer to US 6040467 A, which is incorporated herein by reference. Currently, most epoxidation equipment is oxygen-based, which is preferred. Typically, in oxygen-based processes, the inlet feed gas also contains a dilution gas, which will be discussed in more detail below, to maintain the oxygen concentration below the maximum level permissible for flammability considerations.

[0066] Generally, the oxygen concentration in the inlet feed gas should be lower than the oxygen concentration that would form a combustible mixture at the reactor inlet or outlet under dominant operating conditions. Typically, in practice, the oxygen concentration in the inlet feed gas may not exceed a predetermined percentage (e.g., 95%, 90%, etc.) of the oxygen that would form a combustible mixture at the epoxidation reactor inlet or outlet under dominant operating conditions. Although the oxygen concentration can vary over a wide range, the oxygen concentration in the inlet feed gas is typically at least 0.5 mol% relative to the total inlet feed gas, or at least 1 mol%, or at least 2 mol%, or at least 3 mol%, or at least 4 mol%, or at least 5 mol% on the same basis. Similarly, the oxygen concentration in the inlet feed gas is typically at most 20 mol% relative to the total inlet feed gas, or at most 15 mol%, or at most 12 mol%, or at most 10 mol% on the same basis. In some embodiments, oxygen may be present in the inlet feed gas at a concentration of 1 mol% to 15 mol% relative to the total inlet feed gas, or 2 mol% to 12 mol% or 3 mol% to 10 mol% on the same basis. Generally, as the oxygen concentration in the inlet feed gas increases, the required operating temperature decreases. However, as previously mentioned, in practice, flammability is often the limiting factor for the maximum oxygen concentration in the inlet feed gas. Therefore, to keep it outside the flammable range, the oxygen concentration in the inlet feed gas may decrease as the ethylene concentration in the inlet feed gas increases. Determining a suitable oxygen concentration to be contained in the inlet feed gas, taking into account, for example, the composition of the total inlet feed gas and other operating conditions such as pressure and temperature, is within the capabilities of those skilled in the art.

[0067] In addition to ethylene and oxygen, the inlet feed gas also contains one or more reaction modifiers composed of organochlorides.

[0068] To avoid any doubt, the only reaction modifier in the inlet feed gas used in the method of the present invention is an organochlorine. That is, the inlet feed gas is substantially free of, and preferably completely free of, nitrogen-containing reaction modifiers. Specifically, the inlet feed gas may contain less than 100 ppm of nitrogen-containing reaction modifiers, preferably less than 10 ppm, more preferably less than 1 ppm, and most preferably 0 ppm of nitrogen-containing reaction modifiers. As used herein, the term "nitrogen-containing reaction modifier" refers to a gaseous compound or volatile liquid that exists as nitrogen oxides under oxidizing conditions or is capable of forming nitrogen oxides. Examples of nitrogen-containing reaction modifiers include, but are not limited to, NO, NO2, N2O3, N2O4, N2O5, or any substance capable of forming one of the aforementioned gases under epoxidizing conditions (e.g., hydrazine, hydroxylamine, ammonia, organic nitro compounds (such as nitromethane, nitrobenzene, etc.), amines, amides, organic nitriles (such as methyl nitrite), nitriles (such as acetonitrile)), and combinations thereof.

[0069] Examples of suitable organochlorinated reaction modifiers that can be used for inlet feed include, but are not limited to, C1 to C3 chlorinated hydrocarbons. Specific examples of suitable organochlorides include, but are not limited to, chloromethane, chloroethane, dichloroethane, vinyl chloride, and combinations thereof.

[0070] One or more reaction modifiers are typically present in the inlet feed gas at a total concentration of 0.1 parts per million (ppmv) or higher relative to the total inlet feed gas, or 0.3 ppmv or higher, or 0.5 ppmv or higher on the same basis. Similarly, one or more reaction modifiers are typically present in the inlet feed gas at a total concentration of up to 25 ppmv relative to the total inlet feed gas, or up to 22 ppmv, or up to 20 ppmv on the same basis. In some embodiments, one or more reaction modifiers may be present in the inlet feed gas at a total concentration of 0.1 ppmv to 25 ppmv relative to the total inlet feed gas, or 0.3 ppmv to 20 ppmv on the same basis.

[0071] As discussed in WO 03 / 044002 A1, WO 03 / 044003 A1 and WO 2010 / 123844 A1, it is believed that the ability of organochloride reaction modifiers to improve the performance (e.g., selectivity and / or activity) of epoxidation catalysts containing silver, rhenium and one or more alkali metal promoters on a solid refractory support in ethylene oxide production depends on the extent of the surface of the organochloride chlorination epoxidation catalyst, for example by depositing specific chlorine substances such as atomic chlorine or chloride ions onto the catalyst. However, it is believed that the presence of chlorine-atom-deficient hydrocarbons in the inlet feed gas strips the chloride from the catalyst surface and thus reduces the overall performance enhancement provided by the organochloride reaction modifier.

[0072] Alkane compounds such as ethane or methane are believed to be particularly effective at stripping chlorides from epoxidation catalysts. However, ethylene is also thought to play a role in stripping chlorides from catalysts.

[0073] Some of these hydrocarbons can also be introduced into the ethylene feed as impurities, or due to other reasons (such as the use of recirculation streams). 14 And thus it exists. Typically, when it exists, the inlet feed gas... 2 The preferred concentration of ethane is from 0 mol% to about 2 mol%.

[0074] Considering the inlet feed gas 2 The competitive effect between organochlorine reaction modifiers and chloride-removing hydrocarbons is conveniently represented by the definition of "total catalyst chlorination efficiency value," which indicates the net effect of organochlorine reaction modifiers in chlorination epoxidation catalysts.

[0075] The total chlorination efficiency of the catalyst can be defined as the dimensionless Cl. eff And expressed by the following formula:

[0076]

[0077] MC, EC, EDC, and VC are the concentrations of chloromethane (MC), chloroethane (EC), dichloroethane (EDC), and vinyl chloride (VC) in ppmv, respectively, and CH4, C2H6, and C2H4 are the concentrations of methane, ethane, and ethylene in the inlet feed gas in molar percentage, respectively.

[0078] Therefore, if chloroethane is the inlet feed gas 2 If the only organochlorine reactive modifier present in the gas is chloroethane, then the molecule in Equation (I) is the concentration of chloroethane in ppmv, because the concentrations of chloromethane, dichloroethane, and vinyl chloride will be zero and therefore will not affect the molecule in Equation (I). Similarly, if vinyl chloride, chloromethane, or dichloroethane is used alone or in combination with chloroethane in the inlet feed gas, the molecule in Equation (I) will be adjusted accordingly based on the concentration in ppmv.

[0079] In embodiments where the inlet feed gas contains organic chlorides other than chloromethane, chloroethane, dichloroethane, and / or vinyl chloride, then the Cl... eff The purpose is to subtract the concentration of the organochlorides. Similarly, if any additional hydrocarbons are present in the inlet feed gas besides CH4, C2H6, and C2H4, then the concentration of Cl is subtracted for the purpose of calculating Cl using equation (I). eff The purpose is to ignore the concentration of the additional hydrocarbons.

[0080] Although organochloride reaction modifiers can be provided as a single substance, they can form other substances upon contact with an epoxidation catalyst, resulting in a mixture of organochloride reaction modifiers in the gas phase. Therefore, if the reaction gas is recycled, such as via a recirculation stream... 14 Recirculation will result in a mixture of substances being found at the reactor inlet.

[0081] Specifically, the recirculated reaction gas at the inlet may contain chloroethane, vinyl chloride, dichloroethane, and chloromethane, even if only chloroethane or dichloroethane is supplied to the system. In calculating Cl... eff The concentrations of chloroethane, vinyl chloride, and dichloroethane must be taken into account.

[0082] In typical operation, the total chlorination efficiency (Cl) is adjusted. effThe total chlorination efficiency is selected to achieve the highest possible (maximum) selectivity under a specific set of operating conditions. In this document, the total chlorination efficiency value selected to achieve maximum selectivity under a set of operating conditions is referred to as the "optimal total chlorination efficiency value".

[0083] As described above, the prior art (WO 03 / 044003 A1, WO 2010 / 123844 A1, WO 2010 / 123842A1 and WO 2015 / 100209 A1) teaches that when an epoxidation catalyst containing silver, rhenium and one or more alkali metal promoters ages over time during a process for ethylene epoxidation and the reaction temperature is increased to offset any loss of catalyst activity, the optimal chloride concentration for maximum selectivity also shifts to a higher concentration.

[0084] However, it has been surprisingly found in this invention that the specific epoxidation catalyst described herein does not require a significant change in chloride concentration over time to maintain maximum selectivity at constant ethylene oxide production parameters when the reaction temperature increases due to catalyst aging.

[0085] Therefore, relative to the initial time point during the epoxidation process, the cumulative ethylene oxide yield cumEO1 is at least 0.2 kton ethylene oxide / m³. 3 Catalyst, preferably at least 0.25 kton ethylene oxide / m 3 Catalyst, more preferably at least 0.3 kton ethylene oxide / m 3 Catalyst, (and the process is carried out at a reaction temperature having a value T1 and with Cl having the optimal total catalyst chlorination efficiency value) eff1 The inlet feed gas is operated to produce ethylene oxide, wherein the ethylene oxide production parameters are values ​​of EO1. This invention provides EO equipment operators with a convenient method for subsequent operations of the process, as the epoxidation catalyst further ages over time.

[0086] Therefore, in this invention, when the reaction temperature rises over time to a value Tx to maintain the ethylene oxide production parameters at a value EO1, the EO equipment operator can control the optimal total catalytic chlorination efficiency (Cl) of the inlet feed gas. effx , making Cl effx / Cl eff1 The ratio is in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1, to conveniently maintain maximum catalyst selectivity.

[0087] In this invention, "keeping the ethylene oxide production parameters at the value EO1" means that the ethylene oxide production parameters are substantially the same as EO1. That is, controlling the ethylene oxide production parameters at the target value of EO1, which may fluctuate between ±5%, preferably ±3%, and more preferably ±2% of the target value due to normal operational variations in commercial practice.

[0088] In a preferred embodiment of the invention, at the cumulative ethylene oxide yield cumEOx, the reaction temperature T x It is at least 3°C ​​higher than T1, preferably at least 5°C higher, and most preferably at least 10°C higher.

[0089] In another preferred embodiment of the invention, cumEO x It is at least 0.8 kton ethylene oxide / m³ greater than cumEO1 3 The catalyst, preferably, has a ethylene oxide content at least 1.0 kton / m³ greater than cumEO1. 3 The catalyst, and the optimal total catalytic chlorination efficiency of the inlet feed gas at the cumulative EO production cumEOx. effx Make Cl effx / Cl eff1 The ratio is in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1.

[0090] In another preferred embodiment of the invention, as the cumulative ethylene oxide production increases from cumEO1 to cumEOx, Cl effx / Cl eff1 The ratio remains in the range of 0.8 to 1.2 throughout the entire period of increase, preferably in the range of 0.9 to 1.1.

[0091] In a particularly preferred embodiment of the invention, when the cumulative ethylene oxide yield increases from cumEO1 to reach its final cumEO at the end of its catalytic lifetime... x When the value is , Cl effx / Cl eff1 The ratio is maintained in the range of 0.8 to 1.2 throughout the catalyst lifetime, preferably in the range of 0.9 to 1.1.

[0092] To avoid any doubt, in the method of the present invention, the aspects of the aforementioned preferred embodiments may exist individually or in combination.

[0093] Optionally, the inlet feed gas may also contain carbon dioxide. When present, carbon dioxide is typically present in the inlet feed gas at a concentration of 0.10 mol% or higher relative to the total inlet feed gas, or 0.12 mol% or higher, or 0.15 mol% or higher, or 0.17 mol% or higher, or 0.20 mol% or higher, or 0.22 mol% or higher, or 0.25 mol% or higher on the same basis. Similarly, carbon dioxide is typically present in the inlet feed gas at a concentration of up to 10 mol% relative to the total inlet feed gas, or up to 8 mol%, or up to 5 mol%, or up to 3 mol%, or up to 2.5 mol% on the same basis. In some embodiments, carbon dioxide may be present in the inlet feed gas at a concentration of 0.10 mol% to 10 mol% relative to the total inlet feed gas, or 0.15 mol% to 5 mol%, or 0.20 mol% to 3 mol%, or 0.25 mol% to 2.5 mol% on the same basis.

[0094] As previously mentioned, carbon dioxide is generated as a reaction byproduct and is typically introduced into the inlet feed gas during epoxidation via a recirculated gas stream. Carbon dioxide generally has an adverse effect on catalyst performance, and the operating temperature increases with increasing carbon dioxide concentration in the inlet feed gas.

[0095] Therefore, in the commercial production of ethylene oxide, at least a portion of carbon dioxide is typically removed continuously from the recirculated gas stream (e.g., via a carbon dioxide separation system) to maintain the carbon dioxide concentration in the inlet feed gas at an acceptable level.

[0096] Optionally, the inlet feed gas also contains water vapor. The water vapor may be present in the inlet feed gas at a concentration of 0 mol% to 3 mol% relative to the total inlet feed gas, preferably in the range of 0.1 mol% to 2 mol% on the same basis, and more preferably in the range of 0.2 mol% to 1 mol%.

[0097] The inlet feed gas may optionally also contain a diluent gas, such as nitrogen, methane, or combinations thereof. When used, the diluent gas may be added to the inlet feed gas to increase the oxygen flammability concentration. If desired, the diluent gas may be present in the inlet feed gas at a concentration of at least 5 mol% relative to the total inlet feed gas, or at least 10 mol%, or at least 20 mol%, or at least 25 mol%, or at least 30 mol% on the same basis. Similarly, the diluent gas may be present in the inlet feed gas at a concentration of up to 80 mol% relative to the total inlet feed gas, or up to 75 mol%, or up to 70 mol%, on the same basis. In some embodiments, the diluent gas may be present in the inlet feed gas at a concentration of 20 mol% to 80 mol% relative to the total inlet feed gas, or 30 mol% to 70 mol% on the same basis.

[0098] Furthermore, as previously mentioned, the inlet feed gas may also contain one or more impurities, such as argon, ethane, etc. As those skilled in the art will understand, the type and concentration of impurities present in the inlet feed gas are determined at least in part by the purity of the oxygen and ethylene supplied to the epoxidation reactor and the extent to which any such impurities are removed during the epoxidation process.

[0099] The order and manner in which the components of the inlet feed gas are mixed before contact with the epoxidation catalyst are not limited, and they can be mixed simultaneously or sequentially. However, as those skilled in the art will recognize, for safety reasons, it may be desirable to mix certain components of the inlet feed gas in a specific order. For example, for safety reasons, oxygen may be added to the inlet feed gas after the addition of a dilution gas.

[0100] Similarly, as those skilled in the art will understand, the concentrations of various feed components present in the inlet feed gas can be adjusted throughout the epoxidation process, for example, to maintain desired productivity, optimize the epoxidation process, etc. Therefore, the concentration ranges defined above are selected to cover the maximum possible variations in the composition of the inlet feed gas during normal operation.

[0101] Operating conditions

[0102] The epoxidation process of this invention can be carried out under a wide range of operating conditions, which can vary extensively between different ethylene oxide plants, depending at least in part on the initial equipment design, subsequent expansion projects, feedstock availability, the type of epoxidation catalyst used, process economics, etc. Examples of such operating conditions include, but are not limited to, feed gas composition, reactor inlet pressure, gas flow rate through the epoxidation reactor (typically expressed as gas hourly space velocity or "GHSV"), and ethylene oxide production parameters (i.e., ethylene oxide production rate, ethylene oxide production rate / catalyst volume (operating rate), or product gas ethylene oxide concentration).

[0103] To achieve reasonable commercial ethylene oxide production rates, epoxidation reactions are typically carried out at reaction temperatures of 180°C or higher, or 190°C or higher, or 200°C or higher, or 210°C or higher, or 225°C or higher. Similarly, reaction temperatures are typically 325°C or lower, or 310°C or lower, or 300°C or lower, or 280°C or lower, or 260°C or lower. Reaction temperatures can range from 180°C to 325°C, or from 190°C to 300°C, or from 210°C to 300°C. It should be noted that, as used herein, the term "reaction temperature" refers to any selected temperature that directly or indirectly indicates the catalyst bed temperature. For example, the reaction temperature can be the catalyst bed temperature at a specific location within the catalyst bed or the numerical average of several catalyst bed temperature measurements taken along one or more catalyst bed dimensions (e.g., along length). Alternatively, the reaction temperature can be, for example, the gas temperature at a specific location in the catalyst bed, the numerical average of several gas temperature measurements taken along one or more catalyst bed dimensions, the gas temperature measured at the inlet or outlet of the epoxidation reactor, the numerical average of several coolant temperature measurements taken along one or more catalyst bed dimensions, or the coolant temperature measured at the outlet of the epoxidation reactor. An example of a known device for measuring the reaction temperature is a thermocouple.

[0104] To avoid any doubt, this invention does not rely on any specific method chosen by the operator of an ethylene oxide plant for determining the reaction temperature. The only requirement is that, once chosen, the method for determining the reaction temperature should be consistently applied throughout the entire lifespan of the catalyst.

[0105] In this invention, at the time point when the method is operated at a reaction temperature having a value T1, at least 0.2 kton ethylene oxide / m 3 Catalyst, preferably at least 0.25 kton ethylene oxide / m 3 Catalyst, and more preferably at least 0.3 kton ethylene oxide / m 3 The cumulative ethylene oxide yield cumEO1 of the catalyst.

[0106] The reaction temperature T1 is preferably in the range of 180°C to 260°C, more preferably in the range of 195°C to 250°C, and most preferably in the range of 210°C to 240°C.

[0107] In the method of this invention, as the epoxidation catalyst ages over time, the reaction temperature is increased to a value Tx to maintain the ethylene oxide production parameters at a value EO1, while simultaneously controlling the optimal total catalyst chlorination efficiency (Cl) of the inlet feed gas. effX , making Cl effx / Cl eff1 The ratio is in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1.

[0108] Therefore, the method is subsequently operated such that the cumulative ethylene oxide production cumEO... x At, cumEO x It is at least 0.6 kton ethylene oxide / m³ greater than cumEO1. 3 The catalyst, and more preferably at least 1.0 kton ethylene catalyst, and more preferably at least 0.8 kton ethylene oxide / m³. 3 The catalyst, with an elevated reaction temperature Tx, maintains the ethylene oxide production parameters at EO1 while controlling the optimal total catalyst chlorination efficiency Cl of the inlet feed gas. effX , making Cl effx / Cl eff1 The ratio is in the range of 0.8 to 1.2, preferably in the range of 0.9 to 1.1.

[0109] Reaction temperature T x Preferably, the temperature is in the range of 200°C to 300°C, more preferably in the range of 210°C to 290°C, and most preferably in the range of 220°C to 280°C.

[0110] The epoxidation processes disclosed herein are typically carried out at reactor inlet pressures ranging from 1000 kPa to 3000 kPa, or from 1200 kPa to 2500 kPa. Various known devices can be used to measure the reactor inlet pressure, such as pressure indicating sensors and pressure gauges. Selecting an appropriate reactor inlet pressure, taking into account factors such as the specific type of epoxidation reactor and the required productivity, is within the capabilities of those skilled in the art.

[0111] The gas flow through the epoxidation reactor is expressed as gas hourly space velocity (“GHSV”), which is the quotient of the volumetric flow rate of the inlet feed gas at ambient temperature and pressure (e.g., 0°C, 1 atm) divided by the catalyst bed volume (i.e., the volume of the epoxidation reactor containing the epoxidation catalyst). GHSV represents the number of times the inlet feed gas will displace the volume of the epoxidation reactor per hour if the gas is at ambient temperature and pressure (e.g., 0°C, 1 atm). Generally, as GHSV increases, catalyst selectivity increases. However, for a fixed catalyst volume, increasing GHSV typically leads to increased energy costs; therefore, there is usually an economic trade-off between higher catalyst selectivity and increased operating costs. Typically, in gas-phase epoxidation processes, GHSV ranges from 1,500 / hour to 10,000 / hour.

[0112] Ethylene oxide production parameters are typically described by the operating rate, which refers to the amount of ethylene oxide produced per hour per unit volume of catalyst. As is known to those skilled in the art, the operating rate is a function of several different variables, including but not limited to reactor temperature, reactor pressure, GHSV, and the composition of the inlet feed gas (e.g., ethylene concentration, oxygen concentration, carbon dioxide concentration, etc.). Generally, for a given set of conditions, increasing the reaction temperature increases the operating rate, resulting in increased ethylene oxide yield. However, this increase in temperature typically reduces catalyst selectivity and may accelerate catalyst aging. On the other hand, as epoxidation catalysts undergo natural catalyst aging over time, the operating rate will gradually decrease at a constant reaction temperature. In this case, the reaction temperature is increased to maintain the operating rate at the desired value. Typically, the operating rate in most reactors is 50 kg ethylene oxide / m³. 3 Catalyst / hour - 600kg ethylene oxide / m 3 catalyst / hour (kg / m 3 / h), for example, 50kg / m 3 / h-400kg / m 3 / h or 120kg / m 3 / h-350kg / m 3 / h.

[0113] Those skilled in the art who benefit from this disclosure will be able to select appropriate operating conditions, such as reaction temperature, reactor inlet pressure, GHSV and operating rate, depending on factors such as equipment design, equipment limitations, inlet feed gas composition, and the lifetime of the epoxidation catalyst.

[0114] Ethylene oxide produced by the epoxidation process disclosed herein can be recovered using methods known in the art. In some embodiments, if desired, ethylene oxide can be further reacted with water, alcohol, carbon dioxide, or amine according to known methods to form ethylene glycol, ethylene glycol ether, ethylene carbonate, or ethanolamine, respectively.

[0115] Therefore, the method of the present invention may further include reacting at least a portion of the produced ethylene oxide with at least one reagent selected from the group consisting of water, alcohols, carbon dioxide and amines to form ethylene glycol, ethylene glycol ether, ethylene carbonate and ethanolamine, respectively.

[0116] The conversion to 1,2-ethylene glycol (ethylene glycol) or 1,2-ethylene glycol ether (ethylene glycol ether) may include, for example, reacting ethylene oxide with water, appropriately using an acidic or basic catalyst. For example, to primarily prepare 1,2-ethylene glycol and a smaller amount of 1,2-ethylene glycol ether, ethylene oxide may be reacted with a ten-molar excess of water in the liquid phase at a temperature of 50°C to 70°C and an absolute pressure of 1 bar in the presence of an acid catalyst (e.g., 0.5% w to 1.0% w of sulfuric acid based on the total reaction mixture), or preferably in the gas phase at 130°C to 240°C and an absolute pressure of 20 bar to 40 bar in the absence of a catalyst. Generally, if the proportion of water is reduced, the proportion of 1,2-ethylene glycol ether in the reaction mixture increases. The resulting 1,2-ethylene glycol ether may be a diether, triether, tetraether, or subsequently an ether. Alternative 1,2-ethylene glycol ethers can be prepared by converting ethylene oxide with alcohols, particularly primary alcohols such as methanol or ethanol, by replacing at least a portion of the water with alcohols.

[0117] The conversion to ethanolamine may, for example, involve reacting ethylene oxide with ammonia. Anhydrous ammonia or aqueous ammonia solution may be used, although anhydrous ammonia is generally preferred for the production of monoethanolamine. For methods suitable for the conversion of ethylene oxide to ethanolamine, reference may be made, for example, to US 4845296 A, which is incorporated herein by reference.

[0118] Ethylene glycol and ethylene glycol ethers can be used in a variety of industrial applications, such as in food, beverages, tobacco, cosmetics, thermoplastic polymers, curable resin systems, detergents, and heat transfer systems. Ethylene carbonate can be used as a precursor in, for example, the manufacture of ethylene glycol, or as a diluent, and particularly as a solvent. Ethanolamine can be used, for example, in the treatment of natural gas (“desulfurization”).

[0119] Epoxidation catalyst

[0120] The epoxidation catalysts applicable to the methods described herein comprise a fluoride-mineralized α-alumina support and a silver, rhenium, one or more alkali metal promoters, and optionally one or more co-promoters and / or one or more additional metal promoters deposited on the support.

[0121] The following provides detailed information about the fluoride-mineralized α-alumina support and the epoxidation catalyst comprising the fluoride-mineralized α-alumina support used in the methods of the present invention.

[0122] To avoid any doubt, aspects of the preferred embodiments of the support and catalyst described below can be used alone or in combination in the methods of the present invention.

[0123] Preparation of fluoride-mineralized α-alumina support

[0124] Generally, the fluoride-mineralized α-alumina support in the catalyst used in the method of the present invention is prepared by calcining an α-alumina precursor in the presence of a fluoride mineralizing agent. The specific manner of preparing the fluoride-mineralized α-alumina support is not limited, and therefore any method known in the art for preparing fluoride-mineralized α-alumina supports can be used, such as those methods described in US 3950507 A, US 4379134 A, US 4994588 A, US 4994589 A, and US 6203773 B1, US 2012 / 0108832 A1, and US 2018 / 0161761 A1 in connection with the mineralization of α-alumina, which are incorporated herein by reference.

[0125] One method for preparing an α-alumina support for fluoride mineralization includes mixing an α-alumina precursor with a fluoride mineralizing agent and calcining the combination. The α-alumina precursor can be mixed with the fluoride mineralizing agent by any method known in the art.

[0126] Furthermore, the α-alumina precursor and fluoride mineralizer, along with any other desired raw materials, can be provided in any form and mixed in any order. For example, the α-alumina precursor is typically formed into a shaped body (e.g., a solid already formed into a selected shape suitable for its intended use), and the fluoride mineralizer can be mixed with the α-alumina precursor at any point before, during, or after the formation of such a shaped body, and similarly, it can be mixed with the α-alumina precursor at any point before or during calcination. For example, in some cases, the α-alumina precursor can be mixed with a solution containing a fluoride mineralizer, the combination can be mixed and formed into a shaped body (e.g., extruded), and the shaped body can be calcined to form a fluoride-mineralized α-alumina support. Alternatively, the α-alumina precursor can first be formed into a shaped body, and then the shaped body can be mixed with a fluoride mineralizer (e.g., by impregnating the shaped body with a solution containing a fluoride mineralizer), and subsequently calcined to form a fluoride-mineralized α-alumina support.

[0127] In other cases, the α-alumina precursor can be formed into a shaped body and then contacted with a fluoride mineralizer during calcination (e.g., by calcining the shaped body in a gaseous atmosphere containing a fluoride mineralizer). Therefore, any known preparation method can be used, provided that the α-alumina precursor is calcined in the presence of a fluoride mineralizer.

[0128] Regarding suitable α-alumina precursors, any material capable of at least partially converting to α-alumina upon heating at 1200°C or lower can be used. Suitable α-alumina precursors include, but are not limited to, aluminum trihydrate, such as gibbsite, boehmite, and neo-alumina trihydrate; aluminum oxide hydroxides, such as boehmite, pseudoboehmite, and gibbsite; transitional alumina, such as γ-alumina, δ-alumina, η-alumina, κ-alumina, χ-alumina, ρ-alumina, and θ-alumina; and combinations thereof. As previously stated, α-alumina precursors can be of any form.

[0129] Typically, the α-alumina precursor is included in an amount sufficient to provide, after calcination, a fluoride-mineralized α-alumina support containing at least 80 wt%, or at least 85 wt%, or at least 90 wt%, or at least 95 wt%, or at most 99.9 wt%, or at most 100 wt% of α-alumina.

[0130] As those skilled in the art will recognize, variations in the particle size of the alumina-alumina precursor used have an impact on the physical properties (such as pore size distribution and total pore volume) of the resulting fluoride-mineralized α-alumina support. Similarly, as those skilled in the art will understand, the level of impurities present in the fluoride-mineralized α-alumina support is determined at least in part by the purity of the α-alumina precursor used (along with any other raw materials), the degree of volatilization of impurities during calcination, and whether any impurities are removed during any subsequent washing and / or processing procedures. Common impurities may include silica, alkali metal and alkaline earth metal oxides, and trace amounts of metal- and / or non-metallic additives.

[0131] Regarding suitable fluoride mineralizers, any volatile material or material readily volatilizable under calcination conditions of the α-alumina precursor can be used. Preferably, the fluoride mineralizer is capable of providing volatile fluorine at temperatures of 1200°C or lower, typically 800°C to 1200°C. The fluoride mineralizer can be organic or inorganic and can include ionic, covalent, and polar covalent compounds. The specific form in which the fluoride mineralizer is provided is not limited, and therefore, volatile fluorine can include fluorides, fluoride ions, and fluorine-containing compounds. Similarly, the fluoride mineralizer can be provided in gaseous or liquid solution form (e.g., in the form of a solution containing the fluoride mineralizer), or in gaseous form. Examples of suitable fluoride mineralizers include, but are not limited to, F2, aluminum trifluoride (AlF3), ammonium fluorides such as ammonium hydrogen fluoride (NH4HF2) and ammonium fluoride (NH4F), hydrogen fluoride, hydrofluoric acid, dichlorodifluoromethane (CCl2F2), silicon tetrafluoride (SiF4), silicon hexafluoride ([SiF6]2-), boron trifluoride (BF3), nitrogen trifluoride (NF3), xenon difluoride (XeF2), sulfur hexafluoride (SF6), phosphorus pentafluoride (PF5), carbon tetrafluoride (CF4), trifluoromethane (CHF3), tetrafluoroethane (C2H2F4), trifluoroacetic acid, trifluoromethanesulfonic acid, hexafluorosilicate, hexafluorophosphate, tetrafluoroaluminate, alkali metal (Group 1) fluorides, alkaline earth metal (Group 2) fluorides, Group 4 metal fluorides, Group 6 metal fluorides, Group 8-13 metal fluorides, lanthanide fluorides, and combinations thereof.

[0132] Typically, fluoride mineralizers are used in an amount of at least 0.10% by weight, calculated as the weight of elemental fluorine used relative to the total weight of the α-alumina precursor to which the fluoride mineralizer is added and any optional additives. Preferably, the fluoride mineralizer is used in an amount of not less than 0.20% by weight, more preferably not less than 0.25% by weight. Typically, fluoride mineralizers are used in amounts of up to 5% by weight, or up to 3% by weight, or up to 2.5% by weight. Although amounts exceeding 5% by weight of fluoride mineralizer can be used, such amounts are generally not used as they are considered unnecessary. These amounts refer to the amount of fluoride mineralizer used to prepare the fluoride-mineralized α-alumina support and do not necessarily reflect the amount that may ultimately be present in the fluoride-mineralized α-alumina support, as these amounts will vary depending on the specific process conditions for manufacturing the fluoride-mineralized α-alumina support (e.g., calcination temperature, heating rate, type and amount of α-alumina precursor used, calcination atmosphere, etc.). For further discussion on the effects of fluoride concentration on the properties of the support, see, for example, Shaklee et al., “Growth of α-Al₂O₃ Platelets in the HF-γ-Al₂O₃ System”, Journal of the American Ceramic Society, Vol. 77, No. 11 (1994), pp. 2977-2984.

[0133] If desired, one or more optional additives may be included in the preparation of fluoride-mineralized α-alumina supports. For example, it may be desirable to include one or more additives to promote the formation of shaped bodies and / or modify one or more properties of the resulting fluoride-mineralized α-alumina supports. Suitable additives may include any of a variety of known support additives, including but not limited to binders (e.g., polyolefin oxides, cellulose, alkaline earth metal compounds such as magnesium silicate and calcium silicate, and alkali metal compounds), extrusion aids (e.g., petroleum jelly, hydrogenated oils, synthetic alcohols, synthetic esters, glycols, starches, polyolefin oxides, polyethylene glycol, and mixtures thereof), solvents (e.g., water), peptizing acids (e.g., inorganic acids (such as nitric acid), monofunctional aliphatic carboxylic acids containing 1 to 5 carbon atoms (such as acetic acid, propionic acid, and formic acid), halogenated monofunctional aliphatic carboxylic acids containing 1 to 5 carbon atoms (such as monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid), etc.), fluxes, binders, dispersants, burnout materials (also known as "pore-forming agents"), strength-enhancing additives, etc. Additionally, in some embodiments, α-alumina may be included as an additive. Those skilled in the art can select appropriate amounts of suitable additives, taking into account, for example, the desired properties of the preparation method and the resulting fluoride-mineralized α-alumina support. Furthermore, the α-alumina precursor and any other desired additives can be mixed in any form and in any order; that is, the order in which the α-alumina precursor and any other additives are added is not critical.

[0134] When preparing fluoride-mineralized α-alumina supports, burnout materials may optionally be included to facilitate the molding of the shaped articles and / or alter the porosity of the resulting fluoride-mineralized α-alumina supports. Typically, the burnout material is burned off, sublimated, or volatilized during drying or calcination. Examples of suitable burnout materials include, but are not limited to, crushed nut shells such as pecans, cashews, walnuts, peaches, apricots, and hazelnuts, and particulate polyolefins such as polyethylene and polypropylene.

[0135] Fluoride-mineralized α-alumina supports may optionally contain strength-enhancing additives, for example, to increase the crushing strength and / or improve the abrasion resistance of the fluoride-mineralized α-alumina supports. For descriptions relating to strength-enhancing additives, refer to US 7560411 B2, US 8513156 B2, US 8536083 B2, and US 8603937 B2, which are incorporated herein by reference. Examples of suitable strength-enhancing additives may include, but are not limited to, zirconium materials, lanthanide materials, Group 2 metal materials, inorganic glasses, or mixtures thereof. The specific form in which the strength-enhancing additive exists prior to its incorporation into the fluoride-mineralized α-alumina support is not limited. Thus, zirconium materials, lanthanide materials, and Group 2 metal materials include any particular element itself and compounds of that element.

[0136] Additionally, strength-enhancing additives can be used in the form of compositions comprising strength-enhancing additives, such as solutions or emulsions containing strength-enhancing additives. Exemplary strength-enhancing additives include, but are not limited to, ammonium fluorozirconate, calcium zirconate, zirconium acetate, zirconium acetylacetonate, zirconium carbonate, zirconium fluoride, zirconium oxynitrate, zirconium silicate, lanthanum carbonate, lanthanum fluoride, lanthanum nitrate, lanthanum oxalate, lanthanum oxide, cerium carbonate, cerium fluoride, cerium nitrate, cerium oxalate, cerium oxide, magnesium acetate, magnesium carbonate, magnesium fluoride, magnesium nitrate, magnesium oxalate, magnesium oxide, calcium acetate, calcium carbonate, calcium fluoride, calcium nitrate, calcium oxalate, and calcium oxide. In some embodiments, strength-enhancing additives may be included in amounts from 0.10% to 5% by weight, calculated as the amount of elements used relative to the total weight of the α-alumina precursor in which the strength-enhancing additive is added and any optional additives.

[0137] In embodiments where the strength-enhancing additives include inorganic glass, it is preferred that the melting temperature of the inorganic glass is at most the temperature at which it is calcined. For example, inorganic glass can have a melting temperature below 1200°C. The melting temperature of inorganic glass should be understood as the temperature at which the components of the inorganic glass are heated to a fluid state during glass manufacturing. Typical inorganic glasses may comprise combinations of elements such as silicon, boron, aluminum, or lead with many other elements such as alkali metals and alkaline earth metals. These elements are typically used in the form of their oxides. Exemplary inorganic glasses that can be used for the purposes of this disclosure include, in particular, the following: Na₂O.SiO₂+Na₂O.2SiO₂, Na₂O.2SiO₂+SiO₂ (quartz), K₂O.SiO₂+K₂O.2SiO₂, K₂O.2SiO₂+K₂O.4SiO₂, PbO, 2PbO.SiO₂+PbO.SiO₂, Na₂O.SiO₂+Na₂O.2SiO₂+2Na₂O.CaO.3SiO₂, K₂O.2SiO₂+K₂O.2CaO.9SiO₂+K₂O.4SiO₂, Na₂O.4B₂O₃+SiO₂, and Na₂O.2B₂O₃+Na₂O.SiO₂.

[0138] Optionally, a potassium compound may be included when preparing a fluoride-mineralized α-alumina support. It may be desirable to include a potassium compound, for example, to form a melt with a low melting point during calcination. Suitable potassium compounds may include potassium-containing inorganic or organic compounds, such as inorganic acid salts, organic acid salts, or hydroxides of potassium, for example, potassium nitrate, potassium nitrite, potassium carbonate, potassium bicarbonate, potassium fluoride, potassium sulfate, potassium stearate, potassium silicate, potassium oxalate, potassium acetate, potassium hydroxide, and potassium aluminate. In some embodiments, the potassium compound may be included in an amount from 0.01% to 3% by weight, calculated as the amount of potassium used relative to the total weight of the α-alumina precursor in which the potassium compound is added and any optional additives.

[0139] Typically, prior to calcination, the α-alumina precursor and optional fluoride mineralizer and / or one or more additives are formed into a shaped body. The method of preparing the shaped body is not limited and may include any of several known methods. In some embodiments, the shaped body may be prepared from a malleable mixture of raw materials comprising the α-alumina precursor and optional fluoride mineralizer and / or one or more additives. The malleable mixture of raw materials may be prepared according to any of several known methods (e.g., ball milling, mixing-grinding, belt blending, vertical screw mixing, V-blending, rolling, etc.) and subsequently formed into a shaped body by any of several known methods (e.g., extrusion, spraying, spray drying, agglomeration, pressing, injection molding, slurry casting, casting, roll compaction, etc.). The malleable mixture (e.g., lumps, pastes, etc.) may be prepared as dry (i.e., without a liquid medium) or wet. For applicable methods, see US 5145824 A, US5512530 A, US 5384302 A, US 5100859 A and US 5733842 A, which are incorporated herein by reference.

[0140] Once formed, the molded body can optionally be heated in an atmosphere sufficient to remove water, decompose any organic additives, or otherwise modify the molded body before calcination. Suitable atmospheres include, but are not limited to, air, nitrogen, argon, hydrogen, carbon dioxide, water vapor, those containing fluorine-containing gases, or combinations thereof. If desired, such heating is typically carried out at temperatures ranging from 20°C to 500°C, and preferably from 30°C to 300°C, typically lasting for a period of at least 1 minute to 100 hours, and preferably from 5 minutes to 50 hours. Suitable containers for drying are generally known in the art and may be the same as or different from those used for calcination.

[0141] Calcination is typically carried out at sufficiently high temperatures for sufficiently long periods to induce the mineralization of at least a portion of the α-alumina precursor. Specifically, calcination can be carried out at one or more temperatures and pressures for one or more periods sufficient to convert at least 50%, or at least 75%, or at least 85%, or at least 90%, or at least 95% of the α-alumina precursor into α-alumina. Calcination can be carried out in any suitable atmosphere, including but not limited to air, nitrogen, argon, helium, carbon dioxide, water vapor, those containing fluoride mineralizing agents, and combinations thereof. However, in embodiments in which the shaped body also contains organic burnout material, at least one of the heating and / or calcination is carried out at least partially or entirely in an oxidizing atmosphere, such as an oxygen-containing atmosphere. Calcination is typically carried out at temperatures of 1200°C or lower, and preferably at 750°C or higher, and even more preferably at 900°C or higher. It is generally desirable to maintain the calcination temperature at 1200°C or lower to prevent excessive fluoride release, as this can adversely affect the morphology of the fluoride-mineralized α-alumina support. The pressure during calcination can be any pressure, including negative atmospheric pressure, atmospheric pressure, and ultra-high atmospheric pressure. Preferably, calcination is carried out at atmospheric pressure.

[0142] Depending on the calcination temperature, calcination is typically carried out at atmospheric pressure for up to 5 hours, preferably between 0.5 and 3 hours. As those skilled in the art will recognize, if calcination is carried out at a lower temperature, the mineralization process typically requires a longer time, and similarly, if calcination is carried out at a higher temperature, the mineralization process typically requires a shorter time.

[0143] While this document provides that calcination should generally be carried out at sufficiently high temperatures for sufficiently long times to induce mineralization of at least a portion of the α-alumina precursor (e.g., at temperatures in the range of 750°C to 1200°C for a period of 0.5 to 3 hours, and at atmospheric pressure), this disclosure is not concerned with the manner in which the calcination is performed. Therefore, this disclosure considers calcination variations known in the art, such as holding at a temperature for a period of time and then raising the temperature to a second temperature during a second period of time. Similarly, it should be noted that the surface properties of the resulting fluoride-mineralized α-alumina support depend not only on the calcination temperature but also, at least in part, on the heating rate during calcination. Choosing suitable calcination conditions, considering, for example, the desired properties of the resulting fluoride-mineralized α-alumina support, is within the capabilities of those skilled in the art. For further discussion on the effects of temperature on the mineralization process, see, for example, US 4379134 A, and Daimon et al., “Morphology of Corundum Crystallized by Heating Mixture of η-Al2O3 and AlF3”, Journal of Crystal Growth, Vol. 75 (1986), pp. 348-352.

[0144] Regarding suitable containers for calcination, such containers are generally known in the art. There is no limitation on the specific container used for calcination, and therefore any suitable container known in the art can be used. Examples of such containers include, but are not limited to, furnaces, such as static kilns, rotary kilns, etc. Furthermore, the temperature and pressure within such containers can be measured by any suitable means.

[0145] Following calcination, the resulting fluoride-mineralized α-alumina support may optionally be washed and / or treated before depositing a catalyst material (e.g., silver). Similarly, if desired, any raw material used to form the fluoride-mineralized α-alumina support may be washed and / or treated prior to calcination. Any method known in the art for washing and / or treatment may be used according to this disclosure, provided that such method does not negatively affect the performance of the resulting epoxidation catalyst. For descriptions relating to such methods, reference is made to US 6368998 B1, US 7232918 B2, and US 7741499 B2, which are incorporated herein by reference. If washing is required, it is typically carried out at temperatures ranging from 15°C to 120°C for up to 100 hours, and preferably for a period of 5 minutes to 50 hours. Washing may be performed continuously or intermittently.

[0146] Examples of suitable washing solutions may include, but are not limited to, water (e.g., deionized water), aqueous solutions containing one or more salts (e.g., ammonium salts), amine solutions (e.g., ethylenediamine), aqueous organic diluents, and combinations thereof. Similarly, suitable aqueous solutions may be acidic, alkaline, or neutral. The volume of the washing solution is sufficient to impregnate the fluoride-mineralized α-alumina support until its initial wetting point is reached. Alternatively, a larger volume may be used, and excess solution may be removed from the wet support, for example, by centrifugation. Furthermore, after any washing and / or processing step, it is preferable to dry or calcine the fluoride-mineralized α-alumina support before depositing a catalytic material (e.g., silver). For example, the support may be dried in an air stream, for example, at a temperature of 80°C to 400°C for a sufficiently long period of time.

[0147] Fluoride-mineralized α-alumina supports are commercially available from support manufacturers.

[0148] Fluoride-mineralized α-alumina support - physical properties

[0149] The α-alumina support suitable for fluoride mineralization in this paper can be selected from those with a wide variety of physical properties, including shape, size, bulk density, surface area, water absorption, crushing strength, abrasion resistance, total pore volume, median pore size, pore size distribution, etc.

[0150] In a preferred embodiment, the fluoride-mineralized α-alumina support has a particulate matrix having a layered or sheet-like morphology. More preferably, the layered or sheet-like morphology results in particles with a size greater than 0.1 micrometers in at least one direction having at least one substantially flat main surface.

[0151] Suitable shapes for α-alumina used in fluoride mineralization include any of a variety of shapes known for use as supports, including but not limited to spheres, blocks, flakes, plates, granules, rings, spheres, wheels, trapezoids, annular bodies, double-eared bottles, rings, Raschig rings, honeycomb, monolithic, saddle-shaped, cylinders, hollow cylinders, multi-lobed cylinders, cross-segmented hollow cylinders (e.g., cylinders with at least one spacer extending between the walls), cylinders with gas channels from sidewall to sidewall, cylinders with two or more gas channels, and ribbed or finned structures. Although cylinders are generally circular, other cross-sections such as elliptical, hexagonal, quadrilateral, triangular, and multi-lobed shapes may also be used. Preferably, the α-alumina support for fluoride mineralization is multi-lobed. For a further description of multi-lobed supports, reference can be made to US 2012 / 0171407A1, which is incorporated herein by reference.

[0152] Furthermore, the size of the fluoride-mineralized α-alumina support is generally not limited and can include any size suitable for an epoxidation reactor. For example, the fluoride-mineralized α-alumina support can be a cylindrical shape with a length of 5 to 15 mm, an outer diameter of 5 to 15 mm, and an inner diameter of 0.2 to 4 mm. In some embodiments, the fluoride-mineralized α-alumina support can have a length-to-outer-diameter ratio of 0.8 to 1.2. Additionally, the fluoride-mineralized α-alumina support can be a hollow cylindrical shape with a wall thickness of 1 to 7 mm. Benefiting from this disclosure, considering, for example, the type and construction of the epoxidation reactor in which the fluoride-mineralized α-alumina support will be used (e.g., the length and inner diameter of the inner tube of the epoxidation reactor), selecting a suitable shape and size of the fluoride-mineralized α-alumina support is within the capabilities of those skilled in the art.

[0153] Typically, the surface area of ​​a support represents the amount of surface area per gram of support available for depositing catalytic materials (e.g., silver). The surface area of ​​the fluoride-mineralized α-alumina support used in this paper is not strictly required and can be, for example, 0.1 m² relative to the weight of the fluoride-mineralized α-alumina support. 2 / g to 10m 2 / g, or 0.5m based on the same standard. 2 / g to 5m 2 / g, or 0.7m 2 / g to 3m 2 / g, or at least 0.1m 2 / g, or at least 0.3m 2 / g, or at least 0.5m 2 / g, or at least 0.6m 2 / g, or up to 10m 2 / g, or up to 5m 2 / g, or up to 3m 2 / g. As used herein, “surface area” should be understood as the surface area of ​​a fluoride-mineralized α-alumina support as described in detail in Brunauer, S., Emmett, PY and Teller, E., J. Am. Chem. Soc., 60, 309-16 (1938) by the BET (Brunauer, Emmett and Teller) method.

[0154] The water absorption rate of a carrier is typically expressed as the weight of water absorbed into the pores of the carrier relative to its weight, and is therefore reported as grams of water per gram of carrier, and the unit may be abbreviated as "g / g". Generally, the water absorption rate of the fluoride-mineralized α-alumina carrier applicable herein can be, for example, 0.2 g / g to 1.2 g / g relative to the weight of the fluoride-mineralized α-alumina carrier, or 0.3 g / g on the same basis, or at least 0.2 g / g, or at least 0.3 g / g, or at most 0.8 g / g, or at most 0.7 g / g. As used herein, the term "water absorption rate" should be understood to refer to the water absorption rate of the carrier as measured according to the following procedure: First, a representative sample of approximately 100 g of fluoride-mineralized α-alumina carrier is dried at 110 °C for at least one hour. The sample is then cooled in a desiccator, and the dry weight (D) of each sample is then determined to be accurate to 0.01 g. The sample is then placed in a dish of distilled water and boiled for thirty minutes. When the water boils, cover the sample with the water and use setter pins or similar devices to separate the sample from the bottom and sides of the dish and from each other. After boiling for thirty minutes, transfer the sample to room temperature water and let it soak for another fifteen minutes. After returning to room temperature, gently blot each sample with a damp, lint-free linen or cotton cloth to remove all excess water from the surface and determine the saturated weight (M) of each sample to an accuracy of 0.01 g. The blotting can be done by gently rolling the sample onto a damp cloth that has been previously soaked in water and then simply pressing it to remove any water dripping from the cloth.

[0155] Over-drying should be avoided, as it will introduce errors by drawing water out of the sample's pores. The sample should be weighed immediately after drying. The entire operation should be completed as quickly as possible to minimize errors caused by water evaporation from the sample. The water absorption rate (A) is expressed as the weight of water absorbed relative to the weight of the dried carrier and is determined using the following formula: A = [(MD) / D], where the water absorption rate is expressed in grams of water per gram of carrier (“g / g”). The water absorption rate can also be expressed in “cc / g”, provided that the density of the water is corrected for under the measurement conditions. Alternatively, when measuring the water absorption rate according to the above procedure, it can be conveniently expressed as grams of water absorbed per 100 grams of carrier (e.g., 60 g / 100 g) or as a weight percentage of water absorbed per 100 g of carrier (e.g., 60%). The water absorption rate of a support can be positively correlated with and therefore interchangeable with the term "porosity," which in the field of catalyst supports is generally understood to refer to the open porosity of the support. Typically, as the water absorption rate of the support increases, the ease with which the catalyst material can be deposited on the support increases. However, at higher water absorption rates, fluoride-mineralized α-alumina supports or epoxidation catalysts containing such supports can exhibit lower crushing strength or abrasion resistance.

[0156] The crushing strength of a carrier is typically expressed as the amount of compressive force required to crush the carrier relative to its length, and is therefore reported as the amount of force per millimeter of carrier, and the unit may be abbreviated as "N / mm". The crushing strength of the fluoride-mineralized α-alumina carrier applicable to this document is not strictly required, although it should be sufficient to allow its use in the commercial production of ethylene oxide. Typically, the crushing strength of the fluoride-mineralized α-alumina carrier applicable to this document can be, for example, at least 1.8 N / mm, or at least 2 N / mm, or at least 3.5 N / mm, or at least 5 N / mm, and often up to 40 N / mm, or up to 25 N / mm, or up to 15 N / mm. As used herein, the term "crushing strength" should be understood to refer to the crushing strength of the carrier measured according to ASTM D6175-03, where the test sample is tested as is after its preparation, i.e., step 7.2 of the method, which represents the drying of the test sample, is omitted. For this crushing strength test method, the crushing strength of the carrier is usually measured as the crushing strength of a hollow cylindrical particle with an outer diameter of 8.8 mm, an inner diameter of 3.5 mm, and a length of 8 mm.

[0157] Generally, the abrasion resistance of a carrier is an indicator of its tendency to produce fine particles during transport, handling, and use. The abrasion resistance of the fluoride-mineralized α-alumina carriers used herein is not strictly required, although they should be robust enough to allow their use in the commercial production of ethylene oxide. Typically, the fluoride-mineralized α-alumina carriers used herein may exhibit abrasion of up to 50%, or up to 40%, or up to 30%, and typically at least 5%, or at least 10%, or at least 15%, or at least 20%. As used herein, “abrasion resistance” should be understood to mean the abrasion resistance of a carrier as measured according to ASTM D4058-92, where the test sample is tested as is after its preparation, i.e., step 6.4 of the method is omitted, which represents the drying of the test sample. For this test method, the abrasion resistance of the carrier is typically measured as the abrasion resistance of hollow cylindrical particles with an outer diameter of 8.8 mm, an inner diameter of 3.5 mm, and a length of 8 mm.

[0158] The total pore volume, median pore size, and pore size distribution of the carrier can be measured using a conventional mercury porosimetry apparatus, in which liquid mercury is forced into the pores of the carrier. Greater pressure is required to force mercury into smaller pores, and the measured pressure increment corresponds to the volume increment in the permeated pores, and therefore to the pore size in the incremental volume. As used herein, the pore size distribution, median pore size, and pore volume are measured using mercury porosimetry with a Micromeritics Autopore 9200 model (130° contact angle, mercury with a surface tension of 0.480 N / m, corrected for applied mercury compression) at 2.1 × 10⁻⁶. 8The pressure is measured at Pa. As used herein, median pore size should be understood as the pore size corresponding to a point in the pore size distribution where 50% of the total pore volume exists in pores with a value smaller than (or greater than) that point.

[0159] The total pore volume of the fluoride-mineralized α-alumina support used in this study is not strictly required and can be, for example, at least 0.20 mL / g, at least 0.30 mL / g, at least 0.40 mL / g, at least 0.50 mL / g, and typically at most 0.80 mL / g, at most 0.75 mL / g, or at most 0.70 mL / g. Generally, the ability to deposit catalytic material on the support increases with increasing total pore volume. However, at higher total pore volumes, the fluoride-mineralized α-alumina support or the epoxidation catalyst containing the support may have lower crush strength or abrasion resistance. The median pore size of the fluoride-mineralized α-alumina support used in this study is not strictly required and can be, for example, from 0.50 μm to 50 μm. Furthermore, the fluoride-mineralized α-alumina support used in this study can have a single-peak, bi-peak, or multi-peak pore size distribution.

[0160] As those skilled in the art will understand, the catalytic performance of epoxidation catalysts comprising fluoride-mineralized α-alumina supports will generally vary depending on the specific physical properties of the fluoride-mineralized α-alumina used. Therefore, the range of such physical properties disclosed herein is selected to cover the maximum possible variation in physical properties, the effects of which can be readily determined experimentally.

[0161] Epoxidation catalyst composition

[0162] The epoxidation catalysts applicable herein comprise a fluoride-mineralized α-alumina support as described above, and silver, rhenium, and one or more alkali metal promoters deposited on said support. Optionally, the epoxidation catalyst may also comprise one or more co-promoters, one or more additional metal promoters, and / or combinations thereof. As used herein, the term "optional promoter" refers to one or more co-promoters, one or more additional metal promoters, and any combination thereof.

[0163] In a broad sense, silver is deposited on a fluoride-mineralized α-alumina support in an amount sufficient to catalyze the gas-phase reaction of ethylene with oxygen to produce ethylene oxide. When preparing epoxidation catalysts containing different amounts of silver on supports of similar bulk density, it is convenient to compare the epoxidation catalysts based on the weight of silver, which is typically expressed as a weight percentage of silver as a function of the total weight of the epoxidation catalyst. As used herein, unless otherwise stated, the total weight of the epoxidation catalyst should be understood to refer to the weight of the fluoride-mineralized α-alumina support and all components deposited thereon, including silver, rhenium promoters, alkali metal promoters, and any optional promoters.

[0164] Typically, the epoxidation catalysts used herein contain silver in an amount of 1 wt% to 55 wt% relative to the total weight of the epoxidation catalyst, or 1 wt% to 50 wt% on the same basis, or 5 wt% to 40 wt%, or 8 wt% to 35 wt%, or 10 wt% to 30 wt%, or at least 10 wt%, or at least 15 wt%, or at most 45 wt%, or at most 40 wt%, relative to the total weight of the epoxidation catalyst. The upper and lower limits of suitable silver amounts may vary appropriately depending on the specific catalytic performance characteristics or desired effect or other variables involved, including economic factors.

[0165] Alternatively, the amount of silver contained in the epoxidation catalyst can be expressed as the mass of silver per unit volume of the epoxidation catalyst loaded into the epoxidation reactor (e.g., into a catalyst bed). In this way, the silver loading can be compared between epoxidation catalysts prepared on fluoride-mineralized α-alumina supports of different packing densities. Finally, since the catalyst bed contains a defined volume of epoxidation catalyst, this method of comparing the amount of silver deposited on the epoxidation catalyst is suitable. Therefore, the epoxidation catalyst suitable for this purpose can contain at least 50 kg / m³ relative to the total volume of the epoxidation catalyst loaded into the catalyst bed. 3 Or at least 100 kg / m² based on the same standard. 3 or at least 125 kg / m 3 or at least 150 kg / m 3 The amount of silver. Similarly, the epoxidation catalysts applicable to this document may contain up to 500 kg / m³ of epoxidation catalyst relative to the total volume of the epoxidation catalyst loaded in the catalyst bed. 3 Or, based on the same standard, a maximum of 450 kg / m 3 or up to 400 kg / m 3 or up to 350kg / m 3 The amount of silver. Preferably, the epoxidation catalyst comprises 50 kg / m³ relative to the total volume of the epoxidation catalyst loaded into the catalyst bed. 3 Up to 500kg / m 3Or, based on the same standard, 100 kg / m 3 Up to 450kg / m 3 or 125kg / m 3 Up to 350kg / m 3 Amount of silver.

[0166] In addition to silver, the epoxidation catalysts applicable to this document also include rhenium promoters, alkali metal promoters and optionally one or more co-promoters, one or more other metal promoters and / or combinations thereof.

[0167] Suitable alkali metal promoters for epoxidation catalysts can be selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and combinations thereof. Suitable co-promoters can be selected from the group consisting of sulfur, phosphorus, boron, tungsten, molybdenum, chromium, and combinations thereof. Other suitable metal promoters may include alkaline earth metals (e.g., beryllium, magnesium, calcium, strontium, barium, etc.), titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium, germanium, manganese, and combinations thereof.

[0168] In the reaction process for preparing ethylene oxide, the specific forms of rhenium accelerators, alkali metal accelerators, co-accelerators, and other metal accelerators may be unknown.

[0169] Typically, the specific form in which the rhenium accelerator, one or more alkali metal accelerators, and optional accelerators are provided is not limited, and may include any of a variety of known forms. For example, the rhenium accelerator, one or more alkali metal accelerators, and optional accelerators may suitably be provided in ionic form (e.g., cations, anions, oxoanions, etc.) or in compound form (e.g., rhenium salts, salts of co-accelerators, alkali metal salts, salts of other metal accelerators, etc.).

[0170] Generally, suitable compounds are those that are soluble in suitable solvents, such as aqueous solvents. As used herein, the term "compound" refers to a combination of a particular element with one or more different elements via surface and / or chemical bonds such as ionic and / or covalent and / or coordinate bonds. The term "ionic" or "ionic" refers to the electrochemically charged portion; "cationic" or "cationic" is positive, "anionic" or "anionic" is negative, and "oxoanionic" or "oxoanionic" is the negatively charged portion containing at least one oxygen atom combined with another element (i.e., oxoanion). It should be understood that ions do not exist in a vacuum but are added in combination with counterions that balance the charge. The term "oxidized" refers to a charged or neutral substance in which the element under consideration is bonded to oxygen and possibly one or more different elements via surface and / or chemical bonds such as ionic and / or covalent and / or coordinate bonds. Thus, an oxidized compound is an oxygen-containing compound, and it can also be a mixed, dual, or composite surface oxide. Exemplary oxidizing compounds include, but are not limited to, oxides (containing only oxygen as a second element), hydroxides, nitrates, sulfates, carboxylates, carbonates, bicarbonates, halide oxides, and surface substances, wherein the elements under consideration are directly or indirectly bonded to oxygen in the substrate or surface.

[0171] As those skilled in the art will understand, while a specific form of rhenium promoter, alkali metal promoter, or optional promoter may be provided during catalyst preparation, it is possible for the initially present specific form to transform into another form during the preparation conditions of the epoxidation catalyst and / or during use in the epoxidation process. In fact, the specific form of the rhenium promoter, alkali metal promoter, or optional promoter is not always known once deposited on a fluoride-mineralized α-alumina support and / or during use of the epoxidation catalyst. Furthermore, in many cases, analytical techniques may be insufficient to accurately identify the present form.

[0172] Therefore, this disclosure is not intended to be limited to the exact form of the rhenium promoter, alkali metal promoter, and / or optional promoter that ultimately exists on the epoxidation catalyst during use. Furthermore, it should be understood that while specific compounds may be used during catalyst preparation (e.g., adding cesium hydroxide to the impregnation solution), it is possible that counterions added during catalyst preparation may not be present in the finished epoxidation catalyst (e.g., an epoxidation catalyst prepared using an impregnation solution containing cesium hydroxide can be analyzed to contain cesium but not hydroxide in the finished epoxidation catalyst).

[0173] The epoxidation catalysts applicable herein may comprise a rhenium promoter deposited on an α-alumina support of fluoride minerals in an amount of 0.01 mmol / kg to 50 mmol / kg relative to the total weight of the epoxidation catalyst, or on the same basis, 0.1 mmol / kg to 50 mmol / kg, or 0.1 mmol / kg to 25 mmol / kg, or 0.1 mmol / kg to 20 mmol / kg, or 0.5 mmol / kg. The amount of rhenium promoter, expressed as a fraction of 10 mmol / kg, or 1 mmol / kg to 6 mmol / kg, or at least 0.01 mmol / kg, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at most 50 mmol / kg, or at most 20 mmol / kg, or at most 10 mmol / kg, or at most 6 mmol / kg, is preferably present in the epoxidation catalyst at an amount of 0.25 μmol / m² to 10 μmol / m², or 0.5 μmol / m² to 5 μmol / m², or 1 μmol / m² to 3 μmol / m². For convenience, the amount of rhenium promoter deposited on the epoxidation catalyst is measured in metallic form, regardless of its specific form.

[0174] The degree of benefit obtained within the concentration range defined above will vary depending on one or more properties and characteristics, such as epoxidation conditions, catalyst preparation conditions, physical and surface chemical properties of the support used, the amount of silver deposited on the epoxidation catalyst, the amount of deposited alkali metal promoter, the amount of deposited optional promoter (if any), and the amount of other cations and anions present in the epoxidation catalyst, alone or in combination with rhenium promoter, alkali metal promoter and / or optional promoter.

[0175] Therefore, the above-mentioned limits are chosen to cover the maximum possible variations in properties and characteristics.

[0176] As previously stated, the specific form in which rhenium promoters are provided is generally not limited and may include any of a variety of known forms. For example, rhenium promoters may be provided in the form of metals, ions (e.g., cations, anions, oxyanions, etc.), or rhenium compounds. Examples of suitable rhenium compounds include, but are not limited to, rhenium salts such as rhenium halides, rhenium halide halides, rhenium salts, perrhenium salts (e.g., ammonium perrhenate, alkali metal perrhenate, alkaline earth metal perrhenate, silver perrhenate, etc.), rhenium oxides, and acids. Specific examples of rhenium compounds include, but are not limited to, Re₂O₇, HReO₄, NH₄ReO₄, LiReO₄, NaReO₄, KReO₄, RbReO₄, CsReO₄, and combinations thereof. It should be understood that many rhenium compounds exist that are insoluble in water themselves. However, these compounds can be dissolved using various acids, bases, peroxides, alcohols, etc. After dissolution, these compounds can be used, for example, with an appropriate amount of water or other suitable solvent to provide rhenium promoters. It should also be understood that in many of these compounds, the original compound is no longer present after dissolution. For example, rhenium metal is insoluble in water. However, it is soluble in concentrated nitric acid and hydrogen peroxide solutions. Therefore, rhenium metal can be used to provide rhenium promoters by using suitable reactive solvents.

[0177] The epoxidation catalysts applicable herein may also comprise an alkali metal promoter (i.e., lithium, sodium, potassium, rubidium, cesium, or combinations thereof) deposited on a fluoride-mineralized α-alumina support, in an amount of 0.01 mmol / kg to 500 mmol / kg, or 0.01 mmol / kg to 400 mmol / kg, or 0.1 mmol / kg to 300 mmol / kg, or 0.1 mmol / kg to 250 mmol / kg, or 0.5 mmol / kg to 200 mmol / kg, or 1 mmol / kg to 100 mmol / kg, calculated relative to the total weight of the epoxidation catalyst. The amounts are measured in millimoles per kilogram (mmol / kg), or at least 0.01 mmol / kg, or at least 0.05 mmol / kg, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or up to 500 mmol / kg, or up to 400 mmol / kg, or up to 300 mmol / kg, or up to 250 mmol / kg, or up to 200 mmol / kg, or up to 150 mmol / kg, or up to 100 mmol / kg. For convenience, the amount of alkali metal deposited on the epoxidation catalyst is measured in elemental form, regardless of its form.

[0178] It should be understood that the amount of alkali metal promoter deposited on the fluoride-mineralized α-alumina support is not necessarily the total amount of alkali metal present in the epoxidation catalyst.

[0179] Conversely, the amount deposited reflects the amount of alkali metal promoter that has been added to the fluoride-mineralized α-alumina support (e.g., by impregnation). Therefore, the amount of alkali metal promoter deposited on the fluoride-mineralized α-alumina support does not include any amount of alkali metal that may be locked in the support, for example by calcination, or is unextractable and does not provide a promoting effect in suitable solvents such as water or lower alkanols or amines or mixtures thereof. It should also be understood that the source of the alkali metal promoter can be the fluoride-mineralized α-alumina support itself. That is, the fluoride-mineralized α-alumina support can contain an extractable amount of alkali metal promoter that can be extracted with a suitable solvent such as water or lower alkanols to prepare a solution from which the alkali metal promoter can be deposited or redeposited onto the fluoride-mineralized α-alumina support.

[0180] The degree of benefit obtained within the concentration range defined above will vary depending on one or more properties and characteristics, such as epoxidation conditions, catalyst preparation conditions, the physical and surface chemical properties of the support used, the amount of silver deposited on the epoxidation catalyst, the amount of rhenium promoter deposited on the epoxidation catalyst, the amount of co-promoter and / or other metal promoters deposited on the epoxidation catalyst (if any), and the amount of other cations and anions present in the epoxidation catalyst, alone or in combination with rhenium promoters and / or optional promoters. Therefore, the limits defined above are chosen to cover the maximum possible variation in properties and characteristics.

[0181] As previously stated, the specific form in which alkali metal promoters are provided is generally not limited and may include any of a variety of known forms. For example, alkali metal promoters may be provided in the form of ions (e.g., cations) or alkali metal compounds. Examples of suitable alkali metal compounds include, but are not limited to, alkali metal salts and alkali metal oxides, such as nitrates, nitrites, carbonates, bicarbonates, oxalates, carboxylates, hydroxides, halides, halide oxides, borates, sulfates, sulfites, bisulfites, acetates, tartrates, lactates, oxides, peroxides, and isopropoxides, etc.

[0182] As previously stated, alkali metal promoters may include combinations of two or more alkali metal promoters. Non-limiting examples include combinations of cesium and rubidium; combinations of cesium and potassium; combinations of cesium and sodium; combinations of cesium and lithium; combinations of cesium, rubidium, and sodium; combinations of cesium, potassium, and sodium; combinations of cesium, lithium, and sodium; combinations of cesium, rubidium, and sodium; combinations of cesium, rubidium, potassium, and lithium; and combinations of cesium, potassium, and lithium.

[0183] Furthermore, in embodiments where the epoxidation catalyst comprises a combination of two or more alkali metal promoters, it may be particularly advantageous if the alkali metal promoter comprises potassium and at least one additional alkali metal promoter selected from cesium, rubidium, and combinations thereof, preferably cesium. The amount of potassium deposited on the fluoride-mineralized α-alumina support can be from 0.01 mmol / kg to 50 mmol / kg, or from 0.1 mmol / kg to 400 mmol / kg, or from 0.2 mmol / kg to 30 mmol / kg, or from 0.5 mmol / kg to 20 mmol / kg, or from 1 mmol / kg to 15 mmol / kg, or from 1.5 mmol / kg to 10 mmol / kg, or from 2 mmol / kg to 8 mmol / kg, or at least 0.01 mmol / kg. A quantity of grams, or at least 0.1 mmol / kg, or at least 0.2 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at least 1.75 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or up to 40 mmol / kg, or up to 35 mmol / kg, or up to 30 mmol / kg, or up to 25 mmol / kg, or up to 20 mmol / kg, or up to 15 mmol / kg, or up to 10 mmol / kg. The amount of at least one additional alkali metal promoter selected from cesium, rubidium, and combinations thereof deposited on a fluoride-mineralized α-alumina support may be from 0.1 mmol / kg to 40 mmol / kg, calculated relative to the total weight of the element (e.g., cesium and / or rubidium) of the epoxidation catalyst, or from 0.2 mmol / kg to 35 mmol / kg, or from 0.25 mmol / kg to 30 mmol / kg, or from 0.5 mmol / kg to 20 mmol / kg, or from 1 mmol / kg to 15 mmol / kg, or from 3 mmol / kg to 10 mmol / kg, or to Amounts of less than 0.1 mmol / kg, or at least 0.15 mmol / kg, or at least 0.2 mmol / kg, or at least 0.25 mmol / kg, or at least 0.3 mmol / kg, or at least 0.35 mmol / kg, or at least 0.4 mmol / kg, or at least 0.45 mmol / kg, or at least 0.5 mmol / kg, or up to 40 mmol / kg, or up to 35 mmol / kg, or up to 30 mmol / kg, or up to 25 mmol / kg, or up to 20 mmol / kg, or up to 15 mmol / kg, or up to 10 mmol / kg.In addition, it may be advantageous to deposit potassium and at least one additional alkali metal promoter selected from cesium, rubidium and combinations thereof, in an amount such that the molar ratio of potassium to the additional alkali metal promoter is at least 0.25, or at least 0.5, at least 0.75, at least 1, or at least 1.25, or at most 20, at most 15, at most 10, or at most 7.5, or at most 5.

[0184] Furthermore, in those embodiments in which the alkali metal promoter comprises potassium and at least one other alkali metal promoter selected from cesium, rubidium, and combinations thereof, the deposition of a third alkali metal promoter (preferably lithium) selected from the group consisting of lithium, sodium, and combinations thereof may be additionally advantageous.

[0185] The amount of a third alkali metal promoter selected from lithium, sodium, and combinations thereof deposited on a fluoride-mineralized α-alumina support can be from 0.1 mmol / kg to 400 mmol / kg, calculated relative to the total weight of the element (e.g., lithium and / or sodium) of the epoxidation catalyst, or on the same basis, from 0.5 mmol / kg to 350 mmol / kg, or from 1 mmol / kg to 300 mmol / kg, or from 1 mmol / kg to 200 mmol / kg, or from 1 mmol / kg to 150 mmol / kg, or from 5 mmol / kg to 100 mmol / kg. A quantity of grams, or at least 0.1 mmol / kg, or at least 0.1 mmol / kg, or at least 0.25 mmol / kg, or at least 0.5 mmol / kg, or at least 0.75 mmol / kg, or at least 1 mmol / kg, or at least 2.5 mmol / kg, or at least 5 mmol / kg, or up to 400 mmol / kg, or up to 350 mmol / kg, or up to 300 mmol / kg, or up to 250 mmol / kg, or up to 200 mmol / kg, or up to 150 mmol / kg, or up to 100 mmol / kg.

[0186] Furthermore, in embodiments where the alkali metal promoter comprises potassium, it may be particularly advantageous if the fluoride-mineralized α-alumina support contains nitric acid-leached potassium in an amount less than 85 parts per million (“ppmw”) relative to the weight of the fluoride-mineralized support, or less than 80 ppmw, less than 75 ppmw, or less than 65 ppmw on the same basis. The amount of nitric acid-leached potassium is considered to be the amount that can be extracted from the fluoride-mineralized α-alumina support. Extraction involves extracting a sample of 10 g of the fluoride-mineralized α-alumina support at 100 °C (1 atm) with 100 mL of 10% w nitric acid for 30 minutes, and determining the amount of potassium present in the extract using standard atomic absorption spectrometry. Similarly, in embodiments where the alkali metal promoter comprises potassium, it may also be advantageous if the fluoride-mineralized α-alumina support contains water-leached potassium in an amount less than 40 ppmw relative to the weight of the fluoride-mineralized α-alumina support, or less than 35 ppmw, or less than 30 ppmw on the same basis. The amount of water-leached potassium in a fluoride-mineralized α-alumina support is considered to be the amount that can be extracted from the fluoride-mineralized α-alumina support. Extraction involves extracting a 2-gram sample of the fluoride-mineralized α-alumina support three times by heating at 100°C in 25 g parts of deionized water for 5 minutes, and determining the amount of alkali metal in the combined extracts using known methods, such as atomic absorption spectrometry.

[0187] In these embodiments, potassium can be deposited in amounts of at least 0.5 mmol / kg, at least 1 mmol / kg, at least 1.5 mmol / kg, and at least 1.75 mmol / kg, calculated as the total amount of potassium deposited relative to the weight of the catalyst. Similarly, potassium can be deposited in amounts of up to 20 mmol / kg, up to 15 mmol / kg, up to 10 mmol / kg, and up to 5 mmol / kg, on the same basis. Potassium can be deposited in amounts ranging from 0.5 mmol / kg to 20 mmol / kg, 1 mmol / kg to 15 mmol / kg, 1.5 mmol / kg to 7.5 mmol / kg, and 1.75 mmol / kg to 5 mmol / kg, on the same basis. Additionally, it may be advantageous if the epoxidation catalyst contains a certain amount of potassium such that the amount of water-extractable potassium in the catalyst is at least 1.25 mmol / kg, at least 1.5 mmol / kg, or at least 1.75 mmol / kg relative to the weight of the epoxidation catalyst. Suitably, the epoxidation catalyst may contain water-extractable potassium in amounts ranging from 10 mmol / kg, 7.5 mmol / kg, or 5 mmol / kg on the same basis. Suitably, the epoxidation catalyst may contain water-extractable potassium in amounts ranging from 1.25 mmol / kg to 10 mmol / kg, 1.5 mmol / kg to 7.5 mmol / kg, or 1.75 mmol / kg to 5 mmol / kg on the same basis. The source of the water-extractable potassium may be derived from the components of the fluoride-mineralized α-alumina support and / or the epoxidation catalyst. The amount of water-extractable potassium in the catalyst is considered to be the amount that can be extracted from the catalyst. The extraction involved extracting a 2-gram sample of catalyst three times by heating it at 100°C in 25 g parts of deionized water for 5 minutes, and determining the amount of potassium in the combined extracts using known methods, such as atomic absorption spectrometry.

[0188] Optionally, the epoxidation catalysts used herein may also comprise a co-promoter (e.g., sulfur, phosphorus, boron, tungsten, molybdenum, chromium, or combinations thereof) deposited on a fluoride-mineralized α-alumina support, in an amount of 0.01 mmol / kg to 500 mmol / kg, or 0.01 mmol / kg to 100 mmol / kg, or 0.1 mmol / kg to 50 mmol / kg, or 0.1 mmol / kg to 20 mmol / kg, or 0.5 mmol / kg to 10 mmol / kg, or 1 mmol / kg, calculated on the same basis, based on the amount of the element relative to the total weight of the epoxidation catalyst. The amounts are measured in grams up to 6 mmol / kg, or at least 0.01 mmol / kg, or at least 0.05 mmol / kg, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or up to 100 mmol / kg, or up to 50 mmol / kg, or up to 40 mmol / kg, or up to 30 mmol / kg, or up to 20 mmol / kg, or up to 10 mmol / kg, or up to 5 mmol / kg. For convenience, the amount of co-promoter deposited on the epoxidation catalyst is measured in elemental form, regardless of its form.

[0189] The degree of benefit obtained within the above-defined concentration range will vary depending on one or more properties and characteristics, such as epoxidation conditions, catalyst preparation conditions, the physical and surface chemical properties of the support used, the amount of silver deposited on the epoxidation catalyst, the amount of rhenium and alkali metal promoters deposited on the epoxidation catalyst, the amount of other metal promoters deposited on the epoxidation catalyst (if any), and the amount of other cations and anions present in the epoxidation catalyst, alone or in combination with rhenium promoters, co-promoters, alkali metal promoters, and / or other metal promoters. Therefore, the above-defined limits are chosen to cover the maximum possible variation in properties and characteristics.

[0190] As previously stated, the specific form in which co-accelerators are provided is generally unrestricted and may include any of a variety of known forms. For example, co-accelerators may be provided in the form of ions (e.g., cations, anions, oxyanions, etc.) or co-accelerator compounds (e.g., salts of co-accelerators). Examples of suitable co-accelerator compounds include, but are not limited to, salts of co-accelerator elements, such as oxyanionic compounds of co-accelerator elements (e.g., ammonium oxyanions, such as ammonium sulfate, ammonium molybdate, etc.; alkali metal oxyanions, such as potassium sulfate, cesium chromate, rubidium tungstate, lithium sulfate, sodium tungstate, lithium chromate, etc.). Specific examples of sulfur anions that may be suitably applied include sulfate, sulfite, bisulfite, hydrogen sulfate, sulfonate, persulfate, thiosulfate, dithionite, disulfite, etc. Specific examples of phosphorus and boron anions that may be suitably applied include phosphate, polyphosphate, etc.; and borate, etc. Specific examples of molybdenum, tungsten, and chromium anions that can be appropriately applied include molybdate, dimolybdate, secondary molybdate, other heteropolymolybdates, and heteropolymolybdates; tungstate, secondary tungstate, metatungstate, other heteropolytungstates, and heteropolytungstates; and chromate, dichromate, chromite, and halochromate. Anions can be supplied together with various counterions (e.g., ammonium, alkali metals, alkaline earth metals, and hydrogen (i.e., in acidic form)). Anions can be prepared by reactively dissolving various non-anionic materials such as oxides (e.g., SO2, SO3, MoO3, WO3, Cr2O3, etc.) and other materials such as halides, halide oxides, hydroxy halides, hydroxides, sulfides, etc., of accelerator elements.

[0191] In those embodiments in which the epoxidation catalyst used in the present invention comprises a co-promoter, it may be particularly advantageous if the co-promoter comprises a combination of a first co-promoter selected from sulfur, phosphorus, boron and combinations thereof and a second co-promoter selected from tungsten, molybdenum, chromium and combinations thereof.

[0192] The amount of the first co-promoter deposited on the fluoride-mineralized α-alumina support may be from 0.2 mmol / kg to 50 mmol / kg, calculated relative to the total weight of the epoxidation catalyst, or from 0.5 mmol / kg to 45 mmol / kg, or from 0.5 mmol / kg to 30 mmol / kg, or from 1 mmol / kg to 20 mmol / kg, or from 1.5 mmol / kg to 10 mmol / kg, or from 2 mmol / kg to 6 mmol / kg, or at least 0.2 mmol / kg. The amount may be at least 0.3 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at least 1.75 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or up to 50 mmol / kg, or up to 45 mmol / kg, or up to 40 mmol / kg, or up to 35 mmol / kg, or up to 30 mmol / kg, or up to 20 mmol / kg, or up to 10 mmol / kg, or up to 6 mmol / kg. The amount of the second co-promoter deposited on the fluoride-mineralized α-alumina support may be from 0.1 mmol / kg to 40 mmol / kg, calculated relative to the total weight of the epoxidation catalyst, or from 0.15 mmol / kg to 30 mmol / kg, or from 0.2 mmol / kg to 25 mmol / kg, or from 0.25 mmol / kg to 20 mmol / kg, or from 0.3 mmol / kg to 10 mmol / kg, or from 0.4 mmol / kg to 5 mmol / kg, or at least 0.1 mmol / kg, or An amount of at least 0.15 mmol / kg, or at least 0.2 mmol / kg, or at least 0.25 mmol / kg, or at least 0.3 mmol / kg, or at least 0.35 mmol / kg, or at least 0.4 mmol / kg, or at least 0.45 mmol / kg, or at least 0.5 mmol / kg, or up to 40 mmol / kg, or up to 35 mmol / kg, or up to 30 mmol / kg, or up to 25 mmol / kg, or up to 20 mmol / kg, or up to 15 mmol / kg, or up to 10 mmol / kg, or up to 5 mmol / kg. Furthermore, it may be advantageous to deposit the first and second co-accelerators in quantities such that the molar ratio of the first co-accelerator to the second co-accelerator is greater than 1, or at least 1.25, at least 1.5, at least 2, or at least 2.5. Further preferably, the molar ratio of the first co-accelerator to the second co-accelerator is at most 20, at most 15, at most 10, or at most 7.5. Additionally, preferably, the molar ratio of the rhenium accelerator to the second co-accelerator can be greater than 1, at least 1.25, or at least 1.5.More preferably, the molar ratio of rhenium accelerator to second co-accelerator can be up to 20, up to 15, or up to 10.

[0193] Optionally, the epoxidation catalysts used herein may additionally comprise additional metal promoters (e.g., alkaline earth metals such as beryllium, magnesium, calcium, strontium, barium, etc.; titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium, germanium, manganese, etc.) deposited on a fluoride-mineralized α-alumina support, in an amount of 0.01 mmol / kg to 500 mmol / kg relative to the total weight of the epoxidation catalyst, or on the same basis, 0.01 mmol / kg to 100 mmol / kg, or 0.1 mmol / kg to 50 mmol / kg, or 0.1 mmol / kg to 20 mmol / kg, or 0.5 mmol / kg to 10 mmol / kg. The amounts are measured in moles per kilogram, or from 1 mmol / kg to 6 mmol / kg, or at least 0.01 mmol / kg, or at least 0.05 mmol / kg, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or up to 100 mmol / kg, or up to 50 mmol / kg, or up to 40 mmol / kg, or up to 30 mmol / kg, or up to 20 mmol / kg, or up to 10 mmol / kg, or up to 5 mmol / kg. For convenience, the amount of additional metal promoters in the epoxidation catalyst is measured in elemental form, regardless of their form.

[0194] The degree of benefit obtained within the above-defined concentration range will vary depending on one or more properties and characteristics, such as epoxidation conditions, catalyst preparation conditions, the physical and surface chemical properties of the support used, the amount of silver deposited on the epoxidation catalyst, the amount of rhenium and alkali metal promoters deposited on the epoxidation catalyst, the amount of co-promoters deposited on the epoxidation catalyst (if any), and the amount of other cations and anions present in the epoxidation catalyst, alone or in combination with rhenium promoters, alkali metal promoters, and / or co-promoters. Therefore, the above-defined limits are chosen to cover the maximum possible variation in properties and characteristics.

[0195] As previously mentioned, the specific form in which additional metal promoters are provided is generally not limited and may include any of a variety of known forms. For example, additional metal promoters may be provided in the form of ions (e.g., cations, anions, oxoanions, etc.) or compounds (e.g., salts of other metals).

[0196] Examples of suitable compounds include, but are not limited to, salts of other metals, such as alkaline earth metal salts (e.g., nitrates, nitrites, carbonates, bicarbonates, oxalates, carboxylates, hydroxides, halides, halide oxides, borates, sulfates, sulfites, bisulfites, acetates, tartrates, lactates, and isopropoxides), as well as oxides, halides, and halide oxides of other metals.

[0197] The amounts of silver, rhenium promoters, alkali metal promoters, and optional promoters deposited on fluoride-mineralized α-alumina supports can be analyzed using well-known methods. Technicians can determine the amount of any of these deposited components using, for example, material balance. For instance, if the fluoride-mineralized α-alumina support is weighed before and after the deposition of silver and rhenium promoters, the difference between these two weights will equal the amount of silver and rhenium promoters deposited on the fluoride-mineralized α-alumina support, from which the amount of deposited rhenium promoter can be calculated. Alternatively, the amount of deposited silver and promoter can be calculated based on the ratio of the concentration of silver and promoter in the impregnation solution to the total weight in the finished epoxidation catalyst.

[0198] Alternatively, the amount of promoter deposited on the fluoride-mineralized α-alumina support can also be determined by known leaching methods, wherein the amount of metal leached material present in the fluoride-mineralized α-alumina support and the amount of metal leached material present in the epoxidation catalyst are determined independently, and the difference between the two measurements reflects the total amount of promoter deposited on the fluoride-mineralized α-alumina support. For example, the amount of alkali metal promoter deposited on the epoxidation catalyst can be determined as follows: 10 g of a sample of fluoride-mineralized α-alumina support and 10 g of a sample of epoxidation catalyst are leached separately at 100 °C (1 atm) with 100 mL of 10% w nitric acid for 30 minutes, and the amount of alkali metal promoter present in the extract is determined using standard atomic absorption spectrometry. The difference in the measurements between the support and the catalyst reflects the amount of alkali metal promoter deposited on the support.

[0199] Preparation of epoxidation catalysts

[0200] The preparation of silver-containing epoxidation catalysts is known in the art. There are no specific limitations on the methods used to prepare the epoxidation catalysts suitable for this document, and therefore any methods known in the art can be used. For descriptions relating to the preparation of epoxidation catalysts, references are made to US 4761394 A, US 4766105 A, US 5380697 A, US 5739075 A, US6368998 B1, and US 6656874 B2, which are incorporated herein by reference.

[0201] Generally, the epoxidation catalyst applicable to this article is prepared by the following steps: contacting (e.g., impregnating) a fluoride-mineralized α-alumina support with one or more solutions containing silver, rhenium promoters, alkali metal promoters, and (if desired) optional promoters; and subsequently depositing silver, rhenium promoters, alkali metal promoters, and (if desired) any optional promoters onto the fluoride-mineralized α-alumina support, typically by heating the impregnated support.

[0202] As used herein, the phrase “contacting a fluoride-mineralized α-alumina support with one or more solutions comprising a silver, rhenium, alkali metal, and (if desired) optional accelerators” and similar or related terms refer to the contact of a fluoride-mineralized α-alumina support with a solution comprising a silver, rhenium, alkali metal, and (if desired) optional accelerators in a single or multiple steps; or with two or more solutions (e.g., impregnation) in multiple steps, wherein each solution comprises at least one component selected from a silver, rhenium, alkali metal, and (if desired) optional accelerators, provided that all components of the silver, rhenium, alkali metal, and (if desired) optional accelerators are present individually in at least one solution.

[0203] Furthermore, as is known in the art, the order in which the fluoride-mineralized α-alumina support is contacted with one or more solutions containing silver, rhenium promoters, alkali metal promoters, and (if desired) optional promoters, and the order in which these components are deposited on the fluoride-mineralized α-alumina support, can vary. Thus, the impregnation and deposition of silver, rhenium promoters, alkali metal promoters, and optional promoters (if desired) can be performed simultaneously or sequentially. For example, rhenium promoters, alkali metal promoters, and (if desired) optional promoters can be deposited on the fluoride-mineralized α-alumina support before, simultaneously with, or after the deposition of silver and each other. Similarly, rhenium promoters, alkali metal promoters, and optional promoters can be deposited together or sequentially. Furthermore, for example, silver can be deposited first, followed by simultaneous or sequential deposition of a rhenium promoter, an alkali metal promoter, and (if desired) an optional promoter; or alternatively, a rhenium promoter can be deposited first, followed by simultaneous or sequential deposition of silver, an alkali metal promoter, and (if desired) any optional promoter; or alternatively, an optional promoter can be deposited first, followed by simultaneous or sequential deposition of silver, a rhenium promoter, and an alkali metal promoter. If two or more impregnations are used, the impregnated support is typically dried, or heated between each consecutive impregnation to ensure that the components are deposited on the support. Furthermore, if it is desired that the epoxidation catalyst contains more than 25% by weight of silver, the fluoride-mineralized α-alumina support must typically be subjected to at least two or more consecutive impregnations with a solution containing silver to obtain the desired amount of silver deposited on the support.

[0204] Although the epoxidation catalysts applicable herein are generally prepared by impregnating a fluoride-mineralized α-alumina support with one or more solutions (generally referred to as "impregnation solutions") containing silver, rhenium promoters, alkali metal promoters, and (if desired) optional promoters, this disclosure is not intended to limit it to any particular preparation method. Therefore, any known preparation method may be used, provided that the silver, rhenium promoters, alkali metal promoters, and optional promoters (if any) are deposited in a suitable manner on the fluoride-mineralized α-alumina support. Alternatively, for example, a coating of silver, rhenium promoters, alkali metal promoters, and (if desired) optional promoters may be formed on the fluoride-mineralized α-alumina support from one or more emulsions or slurries containing said components.

[0205] Regarding the specific form of silver used in one or more solutions, any of a variety of known forms may be used, provided that silver can dissolve therein. For example, silver may be suitably provided in the form of silver compounds, such as silver complexes or silver salts, such as silver nitrate, silver oxide, silver carbonate, and silver salts of monocarboxylic acids and polycarboxylic acids and hydroxycarboxylic acids having up to 16 carbon atoms, such as silver acetate, silver propionate, silver butyrate, silver oxalate, silver malate, silver maleate, silver lactate, silver citrate, silver phthalate, higher fatty acid salts, etc.

[0206] Similarly, as mentioned earlier, the specific form of the rhenium promoter, alkali metal promoter, and optional promoters (if any) is not critical, provided that they are soluble in a suitable solvent and do not react undesirably with other components present in the solution. For example, when an alkali metal promoter is deposited simultaneously with silver, the alkali metal promoter used is preferably one that does not react with silver compounds (e.g., silver salts) in the solution to avoid premature precipitation of silver from the solution.

[0207] Various solvents or complexing agents / solvents can be used in one or more solutions to dissolve silver, rhenium accelerators, alkali metal accelerators, and / or any optional accelerators to the desired concentration in the solution. There are no particular limitations on the solvents used, and they may include any solvent or reagent capable of adequately dissolving the silver compound or converting the silver compound into a soluble form, or, if the solution contains rhenium accelerators, alkali metal accelerators, and / or optional accelerators, it should be capable of adequately dissolving these components or converting them into a soluble form. Furthermore, suitable solvents or complexing agents / solvents should be readily removable in subsequent steps by washing, evaporation, or oxidation procedures. Preferably, the solvent or complexing agent / solvent is readily miscible with water, as aqueous solutions can be conveniently used. Examples of suitable solvents or complexing agents / solvents include, but are not limited to, alcohols (including glycols, such as ethylene glycol), ammonia, amines and aqueous mixtures of amines, carboxylic acids such as lactic acid, and mixtures thereof. Additionally, examples of suitable amines include, but are not limited to, organic amines, such as lower alkylene diamines having 1 to 5 carbon atoms (e.g., ethylenediamine), mixtures of lower alkanolamines having 1 to 5 carbon atoms and lower alkylene diamines having 1 to 5 carbon atoms (e.g., a combination of ethylenediamine and ethanolamine), and mixtures of ammonia with lower alkanolamines or lower alkylene diamines having 1 to 5 carbon atoms (e.g., a combination of ethanolamine and ammonia, or a combination of ethylenediamine and ammonia). In those solutions containing silver, these solubilizers / reducing agents are typically added in amounts of 0.1 to 10 moles per mole of silver present.

[0208] Optionally, one or more solutions may also contain a base, such as a metal hydroxide (e.g., lithium hydroxide, cesium hydroxide, rubidium hydroxide, sodium hydroxide), an alkylammonium hydroxide (e.g., tetraalkylammonium hydroxide, such as tetramethylammonium hydroxide or tetraethylammonium hydroxide), 1,8-bis-(dimethylamino)-naphthalene, or combinations thereof, in an amount sufficient to provide a solution having a pH greater than 11.2, more typically at least 11.7, and preferably at least 12, as measured at 20°C. It should be understood that when the solution is not aqueous, the pH of the solution may not be the true pH.

[0209] Furthermore, if a base is involved, it is generally desirable to choose a base that does not alter the metal concentration of one or more solutions, such as an organic base; however, if alteration of the metal concentration of the solution is not a concern, a metallic base may be used.

[0210] After impregnating a fluoride-mineralized α-alumina support with one or more solutions, the support is typically separated from any remaining unabsorbed solution (e.g., by draining excess solution or by using separation techniques such as filtration, centrifugation, or vacuum evaporation at a suitable temperature), and silver, rhenium promoters, alkali metal promoters, and (if desired) any optional promoters are deposited on the support, most commonly by heating (also known as “calcination”). Typically, the impregnated support is heated at a sufficiently high temperature for a sufficiently long period to reduce the silver compound (e.g., silver complex) to metallic silver and form a layer of finely ground silver that binds to the surface of the fluoride-mineralized α-alumina support, including the outer surface and the pore surface. It is observed that the phrase “reduction of silver compound to metallic silver” is used regardless of the form in which silver exists in solution prior to precipitation on the fluoride-mineralized α-alumina support, while the decomposition of the silver compound by heating typically occurs simultaneously. The term “reduction” is preferred herein, taking into account the conversion of positively charged Ag+ ions into metallic Ag atoms.

[0211] Typically, the impregnated carrier can be heated at a temperature ranging from 100°C to 600°C for a period of time ranging from 0.01 hours to 12 hours. The pressure during heating is preferably atmospheric pressure. As those skilled in the art will recognize, heating at lower temperatures generally requires a longer time period, and similarly, heating at higher temperatures generally requires a shorter time period. Although this document provides that heating should generally be carried out at a temperature ranging from 100°C to 600°C for a period of time, and at atmospheric pressure, this disclosure is not concerned with the manner in which such heating is performed. Therefore, this disclosure contemplates heating variations known in the art, such as holding at a temperature for a certain period of time and then raising the temperature to a second temperature during a second time period. Furthermore, heating can be carried out in any suitable atmosphere, such as air or other oxidizing gases, reducing gases, inert gases, or mixtures thereof. Apparatus for such heating can be used to achieve reduction using a static or flowing atmosphere (preferably a flowing atmosphere) of such gases.

[0212] Optionally, the impregnated support can be dried in the presence of an atmosphere that reduces the silver compound to metallic silver. Drying methods known in the art include steam drying, drying in an atmosphere with a controlled oxygen concentration, drying in a reducing atmosphere, and air drying.

[0213] After reduction, the diameter of suitable silver particles can be in the range of 1nm to 1000nm, or the diameter can be greater than 10nm to less than 500nm.

[0214] Although not essential, it is generally preferred that silver is deposited relatively uniformly on a fluoride-mineralized α-alumina support.

[0215] The invention has been generally described, and further understanding can be obtained by referring to the following embodiments, which are provided for illustrative purposes only and are not intended to be limiting unless otherwise stated.

[0216] The method of the present invention will now be described through the following non-limiting embodiments.

[0217] Example

[0218] Example 1 - Preparation of conventional catalysts A, B, and C

[0219] Three separate catalyst compositions, A, B, and C, contain silver, rhenium, and alkali metal promoters on different conventional (non-fluoride mineralized) α-alumina supports A and B. As shown in Table 1 below, catalyst A was prepared on support A, while catalysts B and C were prepared on support B.

[0220] All catalysts were prepared according to known methods, such as those described in WO 2006 / 133183 A2. As measured by the BET method, supports A and B each possessed [a specific characteristic] at 0.7 m [a specific value]. 2 / g to 3.0m 2 Surface area within the range of / g.

[0221] Catalysts A, B, and C each contain silver, rhenium, tungsten, sulfur, lithium, potassium, and cesium.

[0222] Example 2 - Preparation of FMA catalysts D to K

[0223] As shown in Table 1 below, various catalytic compositions D to K containing silver, rhenium promoters and alkali metal promoters on α-alumina (FMA) supports C to G with different fluoride mineralizations are prepared according to known methods, such as those described in WO 2006 / 133183 A2.

[0224] The fluoride-mineralized α-alumina supports C to G used in the catalyst composition each have a layered or sheet-like morphology, such that particles with a size greater than 0.1 micrometers in at least one direction have at least one substantially flat main surface.

[0225] Furthermore, as measured by the BET method, each of the fluoride-mineralized α-alumina supports has a [value missing] at 0.7 m [value missing]. 2 / g to 3.0m 2 The surface area is within the range of / g. The fluoride-mineralized α-alumina supports are each made from a mixture containing an α-alumina precursor, a fluoride mineralizer, and water according to a known method described in US 2018 / 0161761 A1.

[0226] Catalysts D through K each contain silver, rhenium, tungsten, sulfur, lithium, potassium, and cesium.

[0227] Table 1. Catalysts and corresponding supports

[0228]

[0229]

[0230] Example 3 - Testing of catalysts A to G and K under condition 1

[0231] Catalysts A to G and catalyst K were each tested according to the method found in Example 3 of US 8084390 B2.

[0232] Each catalyst is used to produce ethylene oxide from ethylene and oxygen.

[0233] For this purpose, the crushed catalyst was loaded into a stainless steel U-tube. The tube was immersed in a bath of molten metal (hot medium), and its end was connected to a gas flow system. The weight of the catalyst used and the inlet gas flow rate (0.249 Nl / min) were adjusted to obtain a gas hourly space velocity of 3300 Nl / (1·h), as calculated for the uncrushed catalyst. The inlet gas pressure was 1550 kPa (absolute pressure).

[0234] During the entire test run, including startup, the gas mixture passing through the catalyst bed in a "one-pass" operation consisted of 30.0 vol% ethylene, 8.0 vol% oxygen, 5.0 vol% carbon dioxide, 57 vol% nitrogen, and 1.0 to 6.0 vol% (ppmv) chloroethane.

[0235] The initial reactor temperature was 180°C, and it was increased to 225°C at a rate of 10°C / hour, and then adjusted to achieve a constant ethylene oxide content of 3.1 vol% in the outlet gas stream at a chloroethane concentration of 2.0 ppmv.

[0236] Performance data at this conversion level are typically obtained for the initial peak selectivity. The time required to reach the initial peak selectivity (i.e., the highest selectivity achieved in the initial stages of the process) can vary depending on the catalyst used and the parameters of the ethylene epoxidation process. Throughout the test run, the reactor temperature was adjusted to maintain an outlet EO concentration of 3.1% by volume, equivalent to 200 kg EO / m³ per hour. 3 The catalyst's production operating rate. The chloroethane concentration is periodically adjusted to maintain maximum catalyst selectivity.

[0237] Example 4 - Testing of catalysts A, B, E, H, and I under condition 2

[0238] Each of catalysts A, B, E, H, and I was also tested according to the following methods.

[0239] Each catalyst is used to produce ethylene oxide from ethylene and oxygen.

[0240] For this purpose, the crushed catalyst was loaded into a stainless steel U-tube. The tube was immersed in a bath of molten metal (hot medium), and its end was connected to a gas flow system. The weight of the catalyst used and the inlet gas flow rate (0.249 N / min) were adjusted to obtain a gas hourly space velocity of 4800 N / (1·h), as calculated for the uncrushed catalyst. The inlet gas pressure was 2000 kPa (absolute pressure).

[0241] During the entire test run, including startup, the gas mixture passing through the catalyst bed in a "one-pass" operation consisted of 35.0 vol% ethylene, 7.3 vol% oxygen, 0.7 vol% carbon dioxide, 57 vol% nitrogen, and 0.8 vol% to 6.5 vol% ppmv ethane.

[0242] The initial reactor temperature was 180°C, and it was increased to 225°C at a rate of 10°C / hour, and then adjusted to achieve a constant ethylene oxide content of 3.0 vol% in the outlet gas stream at a chloroethane concentration of 1.8 ppmv.

[0243] Performance data at this conversion level are typically obtained for the initial peak selectivity. The time required to reach the initial peak selectivity (i.e., the highest selectivity achieved in the initial stages of the process) can vary depending on the catalyst used and the parameters of the ethylene epoxidation process. Throughout the test run, the reactor temperature was adjusted to maintain an outlet EO concentration of 3.0% by volume, equivalent to 280 kg EO / m³ per hour. 3 The catalyst's production operating rate. The chloroethane concentration is periodically adjusted to maintain maximum catalyst selectivity.

[0244] A comparison of the reactor test conditions described in Examples 3 and 4 above is shown in Table 2 below.

[0245] Table 2. Catalyst Test Conditions

[0246] Test conditions Condition 1 Condition 2 GHSV, Nl / (1·h) 3300 4800 Inlet pressure kPa absolute pressure 1550 2000 Feed ethylene, %m 30 35 Feed oxygen, %m 8.0 7.3 <![CDATA[Feed CO2, %m]]> 5.0 0.7 Export EO, %m 3.1 3.0 <![CDATA[Working rate, kg / m 3 / hr]]> 200 280 Ethyl chloride (EC) reaction modifier, ppm Versions 1.0 to 6.0 0.8 to 6.5

[0247] Example 5 - Catalyst test results under condition 1

[0248] The test results of catalysts A to G and catalyst K under condition 1 are shown in the figure. Figures 2 to 4 middle.

[0249] Figure 2The results show that conventional catalysts A, B, and C, as well as FMA catalysts D, E, F, G, and K, at constant outlet EO concentrations from 1.6 kton EO / m³ under conditions 1 and 3.1 vol%. 3 Catalyst up to 3.0 kton EO / m 3 The cumulative activity curves of catalyst changes during the EO production cycle were tested.

[0250] Figure 3 The figure shows the optimal total chlorination efficiency (Cleff) for catalysts A through G and catalyst K within the same production cycle. It is clear from the figure that the optimal total chlorination efficiency for catalysts D through G and K remains stable, while the optimal total chlorination efficiency for catalysts A, B, and C nearly doubles over time.

[0251] All catalysts A through G and K pass through a 0.2 kton / m³ flow rate. 3 The cumulative ethylene oxide production has achieved stable steady-state operation. At 0.2 kton / m³... 3 At the cumulative ethylene oxide yield, the optimal total chlorination efficiency (GEP) values ​​for catalysts A, B, C, D, E, F, G, and K were 12.0, 8.0, 12.3, 9.1, 7.2, 7.4, 8.1, and 6.3, respectively. These values ​​were used to calculate the optimal GEP value (Cl) at any given time. effX ) and at 0.2kton / m 3 The optimal total chlorination efficiency (Cl) at the cumulative ethylene oxide production rate eff1 The ratio of ). The results of this calculation are shown in Figure 4 In the middle, the ratio of catalysts A, B, and C quickly exceeded 1.2 and continued to increase throughout the entire catalyst operation.

[0252] Surprisingly, for more than 0.2 kton / m 3 Throughout the entire operation of catalysts D, E, F, G, and K, the cumulative yield of ethylene oxide was maintained at a ratio between 0.8 and 1.2.

[0253] Example 6 - Catalyst test results under condition 2

[0254] The test results of catalysts A, B, E, H and I under condition 2 are illustrated in the figure below. Figures 5 to 7 middle.

[0255] Figure 5 The results show that conventional catalysts A and B, as well as FMA catalysts E, H, and I, at constant outlet EO concentrations of 2.1 kton EO / m³ under conditions 2 and 3.0 vol% are used. 3 Catalyst up to 4.5 kton EO / m 3 The cumulative activity curves of catalyst changes during the EO production cycle were tested.

[0256] Figure 6 The optimal total chlorination efficiency (Cl) values ​​for catalysts A, B, E, H, and I within the same production cycle are shown. eff As can be clearly seen from the figure, the optimal total chlorination efficiency values ​​of catalysts E, H, and I remain stable, while the optimal total chlorination efficiency values ​​of catalysts A and B almost double over time.

[0257] All catalysts A, B, E, H, and I pass through a 0.2 kton / m³ flow rate. 3 The cumulative ethylene oxide production has achieved stable steady-state operation. At 0.2 kton / m³... 3 At the cumulative ethylene oxide yield, the optimal total chlorination efficiency (GEP) values ​​for catalysts A, B, E, H, and I are 12.6, 5.7, 6.0, 6.0, and 5.7, respectively. These values ​​are used to calculate the optimal GEP value (Cl) at any given time. effX ) and at 0.2kton / m 3 The optimal total chlorination efficiency (Cl) at the cumulative ethylene oxide production rate eff1 The ratio of ). The results of this calculation are shown in Figure 7 In the middle. The ratio of catalyst A to B quickly exceeded 1.2 and continued to increase throughout the catalyst operation. Surprisingly, for values ​​exceeding 0.2 kton / m³... 3 Throughout the entire run of catalysts E, H, and I, the cumulative yield of ethylene oxide remained between 0.8 and 1.2. In fact, for catalysts E and I, the ratio even remained between 0.9 and 1.1.

[0258] Example 7 - Repeated catalyst test results under condition 1

[0259] At 1.5kton EO / m 3 Catalyst up to 1.9 kton EO / m 3 During the cumulative EO production cycle within the catalyst range, catalyst J was tested twice at a constant outlet EO concentration of 3.1 vol%.

[0260] The purpose of these repeated tests was to demonstrate the reproducibility of the stability of the chlorination efficiency value across multiple runs using the same catalyst formulation. Although the initial optimal total chlorination efficiency value varied slightly between runs due to normal laboratory procedures and measurement variations, each run demonstrated significant stability of the chlorination efficiency value over time.

[0261] During repeated operation of catalyst J, at 0.2 kton / m 3 The optimal total chlorination efficiency (TGE) values ​​at the cumulative ethylene oxide production rate are 6.7 and 7.0. These values ​​are used to calculate the optimal TGE value (Cl) for each corresponding operation at any given time. effX) and at 0.2kton / m 3 The optimal total chlorination efficiency (Cl) at the cumulative ethylene oxide production rate eff1 The ratio of ) was compared with the test results of catalysts A and B under condition 1 (discussed previously).

[0262] The results of these two repeated runs of catalyst J under condition 1 show that Figure 8 In the middle. As previously shown, the total chlorination efficiency ratio of catalysts A and B quickly exceeds 1.2 and continues to increase throughout the catalyst operation. However, for values ​​exceeding 0.2 kton / m³, 3 In two repeated runs of catalyst J, the cumulative ethylene oxide yield remained between 0.8 and 1.2. In fact, for almost the entire run 1 of catalyst J, the ratio even remained between 0.9 and 1.1.

[0263] To address the impact of dopant variability on Cl eff The potential impact of the required dopant levels is assessed by comparing catalysts with similar dopant levels on different supports. The selection of relative dopant levels for catalysts C, D, and E is given in Table 3. Here, the dopant level is calculated as a ratio relative to the comparison catalyst C. It is clear from Table 3 that these catalysts exhibit only minor differences in the relative amount of dopant, thus providing a means of eliminating variables affecting the dopant level differences that influence the required moderating agent concentration.

[0264] This also provides another means to compare the effects of FMA and non-FMA supports on catalyst performance, as it involves chloride moderator requirements during operation.

[0265] The data in Table 3 show that catalysts C, D, and E have very similar dopant formulations. Despite this similarity, significant differences in behavior exist when the required reaction modifier concentrations for catalyst C are compared with those for catalysts D and E.

[0266] Conversely, this is also true because a wide range of dopants for both support types is represented for non-FMA catalysts in catalysts A, B, and C, and for FMA catalysts in catalysts D to K. However, Cl was only observed in the comparison of non-FMA supported catalysts. eff The requirements have increased significantly.

[0267] Table 3. Relative Dopant Levels of Selected Catalysts

[0268] catalyst Re W S Li K Cs C* 1.0 1.0 1.0 1.0 1.0 1.0 D** 1.1 1.0 1.0 1.0 1.0 0.9 E** 1.1 1.0 1.0 1.0 1.0 1.1

[0269] *Compare

[0270] **According to the present invention

[0271] in conclusion

[0272] The lifetime of a typical commercial ethylene oxide catalyst depends on many factors, including catalyst type, operating conditions, equipment and feed constraints, operator economics, legal compliance requirements, and catalyst poisoning events. However, in terms of cumulative ethylene oxide production, the typical range for catalyst lifetime is 1.5 kton EO / m³. 3 Up to 4.0kton EO / m 3 In other words, the data presented in the embodiments of this article represent commercial performance.

[0273] Conventional (non-FMA supported) catalysts A, B, and C exhibit typical reaction modifier concentration profiles during their catalyst lifetime. As previously described in the prior art, as catalyst temperature increases due to long-term deactivation, the optimal reaction modifier concentration (i.e., the optimal total chlorination efficiency) needs to be increased to maintain maximum catalyst selectivity. For catalysts A, B, and C, the reaction modifier concentration (e.g., Cl...) eff The effect of the catalyst operation was almost doubled under conditions 1 and 2.

[0274] Surprisingly, catalysts D through K exhibited very different reaction modifier distributions on the FMA support throughout their catalyst lifetime. Each of these catalysts showed remarkable stability in reaction modifier concentration throughout its lifetime, as seen in the distribution of Cl at any point x. eff (Cl effx ) and 0.2kton / m 3 Cl at the cumulative ethylene oxide production eff (Cl eff1 The ratio indicates that the ratio remains within a narrow range of 0.8 to 1.2.

[0275] This effect is independent of the chosen operating conditions, as catalyst E demonstrated the effectiveness of this technique under both conditions 1 and 2. This effect is also independent of the catalyst dopant formulation, as demonstrated by the behavioral differences between catalyst C and catalysts D and E. Within each support type, a wide range of dopant levels has no effect on the catalyst's behavior in terms of moderating agent level requirements.

[0276] In other words, changes in the dopant levels of catalysts A, B, and C all resulted in a requirement to increase the chloride modifier during the catalyst lifetime. In contrast to non-FMA catalysts, FMA catalysts D through K, with a wide range of dopant levels, showed only small changes in modifier requirements during their catalyst lifetime.

[0277] In practice, this means that commercial equipment operators have an advantage in operating according to the claims of the invention. In the past, operators had to constantly adjust the concentration of the reaction modifier (i.e., the total chlorination efficiency value) to maintain an optimal level that changes over time. If the selected Cl... eff Too high (overly mild) or too low (too mild), this trial-and-error process of finding the optimal shift value leads equipment operators to suboptimal selectivity performance. However, according to the invention and as demonstrated in the examples, the same equipment operator can confidently maintain the reaction modifier concentration (i.e., Cleff) at a constant or near-constant value throughout the catalyst lifetime to ensure maximum catalyst performance.

Claims

1. A method for epoxidizing ethylene, the method comprising: An inlet feed gas containing ethylene, oxygen, and one or more reaction modifiers composed of organochlorides is contacted with an epoxidation catalyst containing a support and having silver, rhenium, and one or more alkali metal promoters deposited on the support; wherein the inlet feed gas has a total catalytic chlorination efficiency value (Cl) expressed by the following formula. eff ):- Wherein [MC], [EC], [EDC] and [VC] are the concentrations of chloromethane (MC), chloroethane (EC), dichloroethane (EDC) and vinyl chloride (VC) in ppmv, respectively, and [CH4], [C2H6] and [C2H4] are the concentrations of methane, ethane and ethylene in the inlet feed gas in molar percentage, respectively; Among them, at least 0.2 kton ethylene oxide / m 3 The cumulative ethylene oxide yield of the catalyst, cumEO1, is obtained at a reaction temperature having a value T1 and using Cl with the optimal total catalyst chlorination efficiency. eff1 The inlet feed gas is operated to produce ethylene oxide, wherein the ethylene oxide production parameter is value EO1; and the method is characterized in that the support is a fluoride-mineralized α-alumina support, and the method is subsequently operated such that the cumulative ethylene oxide production cumEO1 is achieved. x At, cumEO x It is at least 0.6 kton ethylene oxide / m³ greater than cumEO1. 3 Catalyst, wherein the reaction temperature has an increasing value T x To maintain the ethylene oxide production parameters at a value of EO1, while controlling the optimal total catalyst chlorination efficiency (Cl) of the inlet feed gas. effx , making Cl effx / Cl eff1 The ratio is in the range of 0.8 to 1.

2.

2. The method according to claim 1, wherein cumEO1 is at least 0.25 kton ethylene oxide / m 3 catalyst.

3. The method according to claim 1, wherein cumEO1 is at least 0.3 kton ethylene oxide / m 3 catalyst.

4. The method according to any one of claims 1 to 3, wherein the cumulative ethylene oxide production cumEO x At the reaction temperature T x It is at least 3°C ​​higher than T1.

5. The method according to any one of claims 1 to 3, wherein the cumulative ethylene oxide production cumEO x At the reaction temperature T x It is at least 5°C higher than T1.

6. The method according to any one of claims 1 to 3, wherein the cumulative ethylene oxide production cumEO x At the reaction temperature T x It is at least 10°C higher than T1.

7. The method according to any one of claims 1 to 3, wherein cumEO x It is at least 0.8 kton ethylene oxide / m³ greater than cumEO1 3 catalyst.

8. The method according to any one of claims 1 to 3, wherein cumEO x It is at least 1.0 kton ethylene oxide / m³ greater than cumEO1. 3 catalyst.

9. The method according to any one of claims 1 to 3, wherein C1 effx / Cl eff1 The ratio is in the range of 0.9 to 1.

1.

10. The method according to any one of claims 1 to 3, wherein as the cumulative ethylene oxide yield increases from cumEO1 to cumEO... x Cl effx / Cl eff1 The ratio remained in the range of 0.8 to 1.2 throughout the entire period of increase.

11. The method according to any one of claims 1 to 3, wherein as the cumulative ethylene oxide production increases from cumEO1 to cumEO... x Cl effx / Cl eff1 The ratio remained in the range of 0.9 to 1.1 throughout the entire period of increase.

12. The method according to any one of claims 1 to 3, wherein as the cumulative ethylene oxide yield increases from cumEO1 to its final cumEO at the end of the catalyst lifetime... x Value, Cl effx / Cl eff1 The ratio remained in the range of 0.8 to 1.2 throughout the catalyst lifetime.

13. The method according to any one of claims 1 to 3, wherein as the cumulative ethylene oxide yield increases from cumEO1 to its final cumEO at the end of the catalyst lifetime... x Value, Cl effx / Cl eff1 The ratio remained in the range of 0.9 to 1.1 throughout the catalyst lifetime.

14. The method according to any one of claims 1 to 3, wherein the reaction temperature T1 is a value in the range of 180°C to 260°C.

15. The method according to any one of claims 1 to 3, wherein the reaction temperature T x The value is in the range of 200℃ to 300℃.

16. The method according to any one of claims 1 to 3, wherein the ethylene oxide production parameter EO1 is the operating rate and EO1 is selected from 50 kg ethylene oxide / m³. 3 Catalyst / hour to 600 kg ethylene oxide / m 3 Catalyst per hour range.

17. The method according to any one of claims 1 to 3, wherein the inlet feed gas further comprises carbon dioxide at a concentration of 0.10 mol% to 10 mol% relative to the total inlet feed gas concentration.

18. The method according to any one of claims 1 to 3, wherein one or more reaction modifiers are selected from chloromethane, chloroethane, dichloroethane, vinyl chloride, and combinations thereof.

19. The method according to any one of claims 1 to 3, wherein the one or more alkali metal promoters are selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and combinations thereof.

20. The method according to any one of claims 1 to 3, wherein the epoxidation catalyst further comprises one or more co-promoters selected from the group consisting of sulfur, phosphorus, boron, tungsten, molybdenum, chromium, and combinations thereof.

21. The method according to any one of claims 1 to 3, wherein the epoxidation catalyst comprises: The first accelerator is selected from the group consisting of sulfur, phosphorus, boron, and combinations thereof; and The second accelerator is selected from the group consisting of tungsten, molybdenum, chromium, and combinations thereof.

22. The method according to any one of claims 1 to 3, wherein the epoxidation catalyst further comprises another metal selected from the group consisting of beryllium, magnesium, calcium, strontium, barium, titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium, germanium, manganese, and combinations thereof.

23. The method according to any one of claims 1 to 3, wherein, measured according to the BET method, the fluoride-mineralized α-alumina support has a weight of 0.1 m relative to the fluoride-mineralized α-alumina support. 2 / g to 10m 2 Surface area within the range of / g.

24. The method according to any one of claims 1 to 3, wherein, measured according to the BET method, the fluoride-mineralized α-alumina support has a weight of 0.5 m³ relative to the fluoride-mineralized α-alumina support. 2 / g to 5m 2 Surface area within the range of / g.

25. The method according to any one of claims 1 to 3, wherein, measured according to the BET method, the fluoride-mineralized α-alumina support has a weight of 0.7 m relative to the fluoride-mineralized α-alumina support. 2 / g to 3m 2 Surface area within the range of / g.

26. The method according to any one of claims 1 to 3, wherein the fluoride-mineralized α-alumina support has a particulate matrix, the particulate matrix having a layered or sheet-like morphology.

27. The method of claim 26, wherein the layered or sheet-like morphology causes particles with a size greater than 0.1 micrometers in at least one direction to have at least one substantially flat main surface.

28. The method according to any one of claims 1 to 3, further comprising: At least a portion of the generated ethylene oxide is reacted with at least one reagent selected from the group consisting of water, alcohol, carbon dioxide, and amine to form ethylene glycol, ethylene glycol ether, ethylene carbonate, and ethanolamine, respectively.

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