Tantalum-containing mixed metal oxide catalyst for ethane ODH

Abstract

A catalyst is provided that is useful for the oxidative dehydrogenation of ethane, comprising molybdenum, vanadium, tellurium, tantalum, and oxygen, and prepared using a stepwise hydrothermal synthesis procedure. The catalyst has an amorphous content of 30-50% by weight and can be combined with a support / carrier material to form a catalytic material. The catalysts and catalytic materials described exhibit high selectivity to ethylene at high temperatures, with little or no decrease in conversion and selectivity over time, and appear to be insensitive to low residual oxygen concentrations.

Description

[Technical Field]

[0001] (Claiming priority) This application claims priority to U.S. Provisional Application No. 63 / 145,943, filed on 4 February 2021, the entirety of which is incorporated herein by reference. (Technical field) This disclosure generally relates to catalysts and systems for oxidative dehydrogenation (ODH). More specifically, the catalysts include molybdenum (Mo), vanadium (V), tellurium (Te), tantalum (Ta), and oxygen (O). [Background technology]

[0002] Olefins such as ethylene, propylene, and butylene are fundamental building blocks of a variety of commercially valuable polymers. Since naturally occurring sources of olefins do not exist in commercial quantities, polymer producers rely on methods to convert more abundant lower alkanes into olefins. The method chosen by commercial-scale producers today is steam cracking. Steam cracking is a highly endothermic process that exposes alkanes diluted with steam to temperatures of at least 800°C for a short period. The overall cost increases significantly due to the fuel demand to generate the required temperature and the need for equipment capable of withstanding that temperature. Furthermore, the high temperature promotes coke formation, which accumulates in the system, requiring costly periodic reactor shutdowns for maintenance and coke removal.

[0003] Selective oxidation processes, such as oxidative dehydrogenation (ODH), are exothermic alternatives to vapor cracking, producing little to no coke. In ODH, lower alkanes such as ethane are mixed with oxygen in the presence of a catalyst and optionally an inert diluent (e.g., carbon dioxide, methane, nitrogen, or vapor) to produce the corresponding alkene at a relatively low temperature of 300°C. This process can produce a variety of other oxidation products, particularly carbon dioxide and acetic acid. ODH suffers from a lower conversion rate compared to vapor cracking, and this, combined with its low selectivity and the risk of thermal explosion due to the mixing of hydrocarbons and oxygen, may be hindering its commercial adoption.

[0004] A catalyst with high ethylene selectivity is needed for the ethane ODH process. MoVNbTeO is used in the ODH process. x The catalyst has been observed to exhibit a persistent decrease in activity and selectivity over time as the ODH temperature increases. The catalyst's robustness under oxygen-depleted ODH conditions was also tested, and while catalytic activity fully recovered after the air regeneration cycle, selectivity only partially recovered, falling below 90% at a conversion rate of 25%. Operating the reactor at a low temperature of 350°C and a low space velocity resulted in less loss of catalyst selectivity compared to operating the catalyst at temperatures above 360°C. Therefore, MoVNbTeO x To apply catalysts to commercial ODH processes, the plant must be operated at both low temperatures and GHSV temperatures to maintain high catalytic performance. Such process constraints necessitate larger reactor volume sizes (higher CAPEX), narrower operating temperature windows, and ultimately, more challenging reactor operation. [Overview of the Initiative]

[0005] This disclosure relates to a mixed metal oxide catalyst for the oxidative dehydrogenation of ethane, comprising Mo, V, Te, and Ta, which provides high conversion and selectivity. The catalyst is given by formula: Mo a V b Te c Tad O x (wherein a is 1.0, b is from about 0.35 to about 1.0, c is from about 0.1 to about 1.0, d is from about 0.06 to about 1.0, x is a number that satisfies at least the valence of the catalyst.) It is represented by The amorphous content of the catalyst is from about 30 wt% to about 50 wt%.

[0006] As described herein, a catalyst prepared using a stepwise hydrothermal synthesis involving the preparation and mixing of an aqueous precursor salt solution, the hydrothermal baking of the final solution, and calcination exhibits a high selectivity for ethylene at high temperatures.

[0007] Furthermore, Mo a V b Te c Ta d O x When the catalyst is used in an ethane oxidative dehydrogenation process, the conversion and selectivity hardly or not at all decrease over time and do not seem to be sensitive to low oxygen concentrations.

[0008] Also described herein is a process for the oxidative dehydrogenation of ethane in which a catalyst of Mo a V b Te c Ta d O x is contacted with ethane in the presence of oxygen in a reactor to produce an effluent containing ethylene.

Brief Description of the Drawings

[0009] [Figure 1] A cross-sectional view of the setup of a microreactor unit (MRU) is shown. [Figure 2] For catalyst 1.1, a plot of conversion and selectivity as a function of time is shown when the initial operating temperature is 440 °C and then the operating temperature is raised to 448 °C after about 15 hours to obtain a 50% conversion. [Figure 3] For catalyst 1.6, the conversion rate and selectivity as a function of time are plotted when the operating temperature is 442°C and maintained at that temperature. [Figure 4] The conversion rate and selectivity as a function of time for catalyst 1.6, starting at an operating temperature of 470°C and with a residual oxygen content of 0.27 mol%, are plotted. To obtain a conversion rate of 50%, the operating temperature was reduced to 455°C after approximately 87 hours. [Figure 5] The following plots show the conversion rate and selectivity as a function of time for catalyst material 1.1 (including catalyst 1.6 for comparison), when the operating temperature is maintained at 455°C to obtain a conversion rate of 50%. [Figure 6] The following plots show the conversion rate and selectivity as a function of time for catalyst material 1.2 (including catalyst 1.6 for comparison), when the operating temperature is maintained at 450°C to obtain a conversion rate of 50%. [Figure 7] Scanning electron microscope (SEM) images at a magnification of 10,000x are shown for catalysts 1.1 to 1.6 and catalyst 2.1. [Figure 8] SEM images at 10,000x magnification are shown for new and used catalyst materials 1.1, 1.4, and 1.5, as well as new catalyst materials 1.2 and 1.3. [Figure 9] The X-ray diffraction (XRD) spectra for catalysts 1.1, 1.3 to 1.6, and 2.1 are shown. [Figure 10] The XRD spectra for catalyst materials 1.1 to 1.4 and catalyst material 1.6 are shown. [Figure 11] Fourier transform infrared (FTIR) spectra are shown for catalysts 1.1 to 1.6 and catalyst 2.1. [Modes for carrying out the invention]

[0010] In the ODH reaction, which produces ethylene or other alpha-olefins from ethane, selective oxidation (SO) is generally used. Embodiments described herein provide catalytic systems for selective oxidation reactions.

[0011] This specification provides for MoVTeTaO, which is useful for the ODH process of ethane having high ethylene selectivity. x It is a catalyst. In some embodiments, the catalyst exhibits desirable process performance characteristics. In some embodiments, MoVTeTaO x The catalyst is MoVTeNbO, which is known in the art. x It exhibits improved properties compared to a catalyst. In some embodiments, MoVTeTaO x The catalyst remains stable and maintains high activity and selectivity during operation at temperatures above 400°C. In some embodiments, the catalyst maintains high activity and selectivity even after a slight loss of initial activity. In some embodiments, this slight loss of initial activity is due to the catalyst's equilibrium. The improved stability is beneficial because it provides the option to operate at higher reactor temperatures than previously considered.

[0012] In some embodiments, MoVTeTaO x The catalyst exhibits high tolerance to low residual oxygen conditions while producing high conversion and selectivity. This is beneficial because it allows for higher conversion rates and, consequently, higher ethylene yields without negatively impacting catalyst lifetime. The low residual oxygen in the resulting gaseous product stream may also contribute to reduced oxygen separation requirements downstream of the ODH process.

[0013] In some embodiments, MoVTeTaO xBy using a catalyst, acetic acid production is reduced, and high ethylene selectivity is achieved. High ethylene selectivity means that CAPEX and OPEX for acetic acid purification, which is part of the downstream process in the ODH plant, can be reduced. This also means that the sale of acetic acid products will be easier to manage, given the very low demand for acetic acid in the North American market (34 kTA).

[0014] Accordingly, the catalysts provided herein exhibit improved properties compared to other tantalum-containing ODH catalysts disclosed in the art. For example, the catalysts of the disclosure can be operated at much higher temperatures without compromising selectivity (resulting in high conversion rates); the catalysts of the disclosure are not deactivated by low oxygen concentrations (allowing for almost complete removal of O2 from the product stream); the catalysts of the disclosure produce low levels of acetic acid; the catalysts of the disclosure are prepared using stepwise hydrothermal synthesis, as opposed to "single-pot" synthesis; the catalysts of the disclosure contain a much higher M1 phase compared to previously disclosed tantalum-containing catalysts; and the catalysts of the disclosure have a distinctive X-ray diffraction (XRD) profile.

[0015] Provided herein are oxidative dehydrogenation catalyst materials comprising molybdenum (Mo), vanadium (V), tellurium (Te), tantalum (Ta), and oxygen (O). The catalyst is of the formula MoVTeTaO x It is represented by the formula Mo a V b Te c Ta d O x The catalyst has the following characteristics: a is 1.0, b is approximately 0.35 to approximately 1.0, c is approximately 0.1 to approximately 1.0, d is approximately 0.06 to approximately 1.0, and x is a number that satisfies at least the valence of the catalyst. In some embodiments, the catalyst is of the formula Mo1V 0.35-1.0 Te 0.1-1.0 Ta 0.06-1.0 It has. In some embodiments, the catalyst is of formula Mo1V 0.39-0.49 Te 0.12-0.17 Ta 0.06-0.15It has. In some embodiments, the catalyst is of formula Mo1V 0.49 Te 0.15 Ta 0.07 It has the following properties. In some embodiments, the amorphous content of the catalyst is about 30% to about 50% by weight.

[0016] In some embodiments, a is 1.0. In some embodiments, b is approximately 0.35 to approximately 1.0. In some embodiments, b is approximately 0.35 to approximately 0.75. In some embodiments, b is approximately 0.39 to approximately 0.49. In some embodiments, b is approximately 0.45 to approximately 0.7. In some embodiments, b is approximately 0.49. In some embodiments, c is approximately 0.1 to approximately 1.0. In some embodiments, c is approximately 0.1 to approximately 0.2. In some embodiments, c is approximately 0.12 to approximately 0.17. In some embodiments, c is approximately 0.14 to approximately 0.18. In some embodiments, c is approximately 0.15. In some embodiments, d is approximately 0.06 to approximately 1.0. In some embodiments, d is approximately 0.06 to approximately 0.15. In some embodiments, d is approximately 0.06 to approximately 0.15. In some embodiments, d is approximately 0.06 to approximately 0.10. In some embodiments, d is approximately 0.07. In some embodiments, x is the number of oxygen atoms required to satisfy the valence of the catalyst at least.

[0017] In some embodiments, the amorphous content of the catalyst is about 30% to about 50% by weight. In some embodiments, the amorphous content of the catalyst is about 30% to about 40% by weight. In some embodiments, the amorphous content of the catalyst is about 33% to about 36% by weight. In some embodiments, the amorphous content of the catalyst is about 34% to about 35% by weight.

[0018] MoVTeTaO xThe catalyst is preferably prepared using a synthesis procedure comprising three general steps. The first step involves preparing aqueous solutions of catalyst precursor salts of the elements molybdenum, vanadium, tellurium, and tantalum. The molybdenum and tellurium components can be prepared as a mixed aqueous preparation to which a vanadium aqueous preparation can be added. Then, an aqueous tantalum preparation can be added to form the final aqueous composition. The second step involves hydrothermally baking the final aqueous composition to form a slurry, which can be filtered and rinsed to isolate the solid catalyst. The final step involves calcining the solid catalyst. The stepwise hydrothermal method described differs from known "single-pot" synthesis procedures in that all components are added simultaneously in a single pot to form the product in situ.

[0019] The MoVTeTaO described x When the catalyst is analyzed using X-ray diffraction (XRD), it exhibits a pattern with distinct peaks. In some embodiments, the XRD pattern includes peaks at °2θ values ​​of 22.2±0.2, 26.7±0.2, and 28.3±0.2. In some embodiments, the XRD pattern includes peaks at °2θ values ​​of 7.9±0.2, 9.0±0.2, 22.2±0.2, 23.0±0.2, 25.0±0.2, 26.7±0.2, and 28.3±0.2.

[0020] Furthermore, this specification provides catalytic materials comprising a catalyst, such as the catalyst of this disclosure, and a catalyst support or carrier. Some supports are particularly suitable for catalysts in that they are chemically compatible and do not substantially affect ethylene selectivity. Other supports may be less compatible and may significantly degrade catalytic performance, such as by reducing ethylene selectivity. Therefore, not just any support can be selected, and a wise selection of support is necessary based on both short-term and long-term catalytic performance tests. In some embodiments, emphasis is placed on long-term tests demonstrating no loss of selectivity due to operating time (e.g., more than 48 hours of operating time (TOS)). In some embodiments, the catalyst support or carrier is selected from the group consisting of precipitated synthetic silica, fumed synthetic silica, silica-alumina, α-alumina, and anatase-type titania. In some embodiments, the catalyst support or carrier is precipitated synthetic silica. In some embodiments, the catalyst support or carrier is fumed silica.

[0021] Furthermore, provided herein is a process for the oxidative dehydrogenation of ethane, the process comprising contacting a gaseous feed containing ethane and oxygen with a catalyst in a reactor to produce an effluent containing ethylene, the catalyst of formula: Mo a V b Te c Ta d O x (In the formula, a is 1.0, b is approximately 0.35 to approximately 1.0. c is approximately 0.1 to approximately 1.0. d is approximately 0.06 to approximately 1.0. x is a number that satisfies at least the valence of the catalyst. It is represented as, The amorphous content of the catalyst is approximately 30% to 50% by weight.

[0022] Reactors suitable for use with the catalysts and processes described herein include fixed-bed reactors in which the catalyst is immobilized in a catalyst bed. Shell-tube reactors are particularly suitable for use with the catalysts and processes described herein, and these include, but are not limited to, shell-tube reactors equipped with molten salt cooling.

[0023] The ability of a catalyst in the ethane ODH process to convert ethane to ethylene can be evaluated by determining the conversion rate and selectivity. The conversion rate is described in terms of the temperature at which a particular molar percentage of ethane is converted to ethylene and related by-products. Selectivity is described in terms of what percentage of the converted ethane is converted to ethylene (or a specific by-product). The conversion rate typically increases with increasing temperature. Unfortunately, in some ODH catalysts, the selectivity to ethylene decreases with increasing temperature, and in some cases, the conversion rate actually decreases at sufficiently high temperatures, potentially leading to irreversible deactivation of the catalyst. Commercial success may depend on whether a catalyst that operates at higher temperatures can be used while maintaining a selectivity to ethylene above 90%. Maximizing the conversion rate while maintaining selectivity is highly beneficial.

[0024] In some embodiments, the catalyst described exhibits a conversion rate of 50 mol% and an ethylene selectivity of 90% or more at temperatures of approximately 350°C to approximately 475°C when used in a process for the oxidative dehydrogenation of ethane. In some embodiments, the catalyst described exhibits a conversion rate of 50 mol% and an ethylene selectivity of 90% or more at temperatures of 390°C to 450°C when used in a process for the oxidative dehydrogenation of ethane. In some embodiments, the catalyst described exhibits a conversion rate of 50 mol% and an ethylene selectivity of 90% or more at temperatures of 400°C to 450°C when used in a process for the oxidative dehydrogenation of ethane.

[0025] In some embodiments, when used in a process for the oxidative dehydrogenation of ethane, the catalyst described exhibits a conversion rate of 35 mol% and an ethylene selectivity of 90% or more at a temperature of at least 400°C.

[0026] Furthermore, ODH catalysts are known to decrease in activity over time, with the most significant decrease occurring immediately after the catalyst is put into use while still new. Catalysts that maintain activity and selectivity over time may prove commercially beneficial because they have a longer period before replacement is required. In some embodiments, the catalyst does not show a significant decrease in activity or selectivity for at least 110 hours after initial activation. In some embodiments, when used in a process for the oxidative dehydrogenation of ethane, the described catalyst exhibits an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at temperatures above 400°C for at least 110 hours. In some embodiments, when used in a process for the oxidative dehydrogenation of ethane, the described catalyst exhibits an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at temperatures between 350°C and 475°C for 110 hours. In some embodiments, when the catalyst described is used in a process for the oxidative dehydrogenation of ethane, it exhibits an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at a temperature of 400°C to 450°C for 110 hours.

[0027] <Definition> As used herein, the term “catalytic material” refers to a material comprising a combination of an active catalyst capable of promoting the oxidative dehydrogenation of ethane to ethylene and a support / support material. The catalytic material may be a plurality of particles or a formed catalytic material. Non-limiting examples of formed catalytic materials include extruded catalytic materials, pressed catalytic materials, and cast catalytic materials. Non-limiting examples of pressed and cast catalytic materials include pellets such as tablets, oval or spherical particles.

[0028] As used herein, the term “catalyst” generally refers to the active catalytic portion of a catalytic material. The catalyst is generally subjected to further processes to form a catalytic material. The catalytic material may also be subjected to further processes to form a final catalytic material.

[0029] As used herein, the terms “oxidative dehydrogenation” or “ODH” refer to a process that combines the endothermic dehydration of an alkane with the strong exothermic oxidation of hydrogen, as further described herein.

[0030] Where used in this disclosure, the term "35% conversion temperature" refers to the temperature at which 35 mol% of ethane in a gas stream is converted to products other than ethane, and is determined using the microreactor unit (MRU) and test conditions described below. The conversion rate of the feed gas is calculated as the change in the mass flow rate of ethane in the product compared to the mass flow rate of the feed ethane, using the following formula: TIFF0007854448000001.tif32147 Here, C is the mole percent of the feed gas converted from ethane to another product (i.e., ethane conversion), and X is the molar concentration of the corresponding product in the gaseous effluent leaving the reactor. Next, the ethane conversion rate is plotted as a function of temperature to obtain a linear algebraic equation. Solving the linear equation for the ethane conversion rate determines the temperature at which the ethane conversion rate reaches 35% (i.e., the 35% conversion temperature). The "50% conversion temperature" refers to the temperature at which 50 mole percent of ethane in the gaseous flow is converted to products other than ethane, and can be determined using the same linear equation.

[0031] As used in this disclosure, the term "selectivity to ethylene" refers to the molar percentage of ethane converted or reacted that forms ethylene. The selectivity of an oxidative dehydrogenation catalyst to ethylene can be determined using the MRU and test conditions described below. The selectivity of an oxidative dehydrogenation catalyst to ethylene can be determined using the following formula: TIFF0007854448000002.tif28147 Here, SC2H4 X is the selectivity for ethylene, and X is the molar concentration of the corresponding compound in the gaseous effluent exiting the reactor. It is noteworthy that the selectivity for ethylene is determined at either the indicated conversion temperature, the 35% conversion temperature, or the 50% conversion temperature. Thus, after the 35% conversion temperature is determined, X at the 35% conversion temperature is... C2H4 , X CO2 , X CO Using the corresponding values, the above equation for the selection rate is solved.

[0032] The oxidative dehydrogenation of ethane can also lead to the formation of various other by-products, including maleic acid, propionic acid, ethanol, acetaldehyde, and their derivatives (for example, maleic anhydride is produced from the hydrolysis of maleic acid). These by-products are present in small amounts, less than 0.1 mol% of the product, and are therefore not included in the calculations of conversion rates and selectivity.

[0033] Unless otherwise indicated in the examples of operation or elsewhere, all numbers or expressions used herein and in the claims to refer to quantities of ingredients, reaction conditions, etc., should be understood in all cases to be modified by the term "approximately." Accordingly, unless otherwise indicated, the numerical parameters described herein and in the appended claims are approximations that may vary depending on the characteristics that this disclosure wishes to achieve. At the very least, each numerical parameter should be interpreted by applying ordinary rounding techniques, at least in light of the reported number of significant figures, not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims.

[0034] Although the numerical ranges and parameters representing the broad scope of this disclosure are approximations, the numerical values ​​described in the specific examples are reported as accurately as possible. However, every numerical value inherently contains a certain degree of error that inevitably arises from the standard deviation observed in each test measurement.

[0035] Furthermore, it should be understood that the numerical ranges described herein are intended to include all subranges contained therein. For example, the range "1 to 10" is intended to include all subranges between the stated minimum value "1" and the stated maximum value "10". That is, the minimum value is 1 or greater and the maximum value is 10 or less. Since the disclosed numerical ranges are continuous, they include all values ​​between the minimum and maximum values. Unless otherwise specified, the various numerical ranges specified in this application are approximations. [Examples]

[0036] Catalysts containing Mo, V, Te, and Ta were prepared using the stepwise hydrothermal procedure described below, and their characteristics were evaluated according to activity (conversion rate and selectivity), composition (FTIR, XRD, SEM, PSD), and durability (TOS, low-oxygen conditions). The selected catalysts were further combined with selected support materials to form catalyst materials, which were then subjected to further characterization.

[0037] The general synthesis procedure involves three general steps. The first step was to prepare aqueous solutions of catalyst precursor salts of the elements molybdenum, vanadium, tellurium, and tantalum. The molybdenum and tellurium components were prepared as mixed aqueous preparations with the addition of an aqueous vanadium preparation. Then, an aqueous tantalum preparation was added to form the final aqueous composition. The second step involved hydrothermally baking the final aqueous composition to form a slurry, which was then filtered and rinsed to isolate the solid catalyst. The final step involved calcining the solid catalyst. The synthesis procedure for catalyst 1.1, including the steps described below, served as the baseline procedure for all examples. Modifications to the procedure for additional examples are noted.

[0038] <Aqueous preparation> Tantalum oxalate was prepared from tantalum ethoxide according to the general description in the literature: Grasselli et al., (2006), Topics in Catalysis 38, pp. 7-16. Aqueous oxalic acid was prepared by dissolving 12.7259 g of anhydrous oxalic acid (C2O4H2) in 118 mL of distilled water using a 65°C water bath and stirring at 250-450 rpm (enough to create a small vortex) to obtain a colorless, transparent solution. 19.10 g of Ta(OEt) was added to the aqueous oxalic acid solution. 5(l) When added all at once, a white suspension is immediately formed, which is stirred at 65°C for 2 days to obtain a concentration of 0.4 mol Ta / LH x [Ta(C2O4)] 3(aq) A colorless, transparent aqueous solution of [ ] was formed.

[0039] Ammonium heptamolybdate tetrahydrate ((NH4)6Mo7O 24 · 4H2O (s) 463.89 g of (OH) was dissolved in 3500 mL of distilled water to form a colorless, transparent solution, which was then stirred at 80°C. 6(s) , 100.55g warm aqueous (NH4)6Mo7O 24 It was added all at once to form a turbid solution. By slowly adding 191 mL of aqueous NH4OH (28 wt% NH3 in water), the pH of the turbid solution was adjusted to 7.5, forming a colorless, transparent solution. The pH of the solution was monitored with a temperature-compensated pH meter. This solution was stirred at 80°C in ambient air for approximately 48 hours to evaporate all water and isolate a colorless, transparent solid. The obtained colorless solid was crushed and dried overnight to obtain (NH4)6Mo6TeO 24 ·7H2O (s) A white powder was produced, and 59.16 g of it was dissolved in 750 mL of distilled water (reserving 50 mL of distilled water for rinsing for all subsequent mixing and transfer steps) while stirring at 60°C to prepare a colorless, transparent solution.

[0040] 39.44 g of vanadium sulfate (VOSO4·3.36H2O) was dissolved in 240 mL of distilled water while stirring at 60°C to prepare a clear blue solution. The warm VOSO4 solution was then heated in warm aqueous (NH4)6Mo6TeO 24 The solution was added dropwise over approximately 11 minutes to produce a black solution. Immediately after the black MoVTe solution was formed, H x [Ta(C2O4)] 3(aq) The entire solution of [ ] was added dropwise to produce an olive-green solution, which was then stirred in air at 60°C for 1 hour, during which time a fine precipitate formed.

[0041] <Hydrothermal Baking> The olive-green slurry at 60°C was poured into a glass liner for a 2000 mL PARR autoclave equipped with an overhead stirring reactor head and then transferred to the autoclave. The autoclave was closed, the atmosphere inside the autoclave was evacuated (vacuumed), and nitrogen (12 psig from the bulk nitrogen line) was filled 10 times. The autoclave was sealed under 12 psig of bulk nitrogen and placed inside a heating mantle for hydrothermal baking. The heating mantle and autoclave were well insulated and heated at an externally controlled temperature of 175°C for 48 hours, allowing the hydrothermal reaction to proceed in a static state. The externally set temperature was measured via a thermocouple placed on the reactor wall below the heating mantle. The temperature of the solution, measured via a wet process thermocouple through a Hastelloy thermowell, was recorded as 166°C. The time to raise the internal temperature from room temperature to 164°C was 4.5 hours.

[0042] The reactor pressure and volume were maintained using the apparatus described in U.S. Patent No. 110,589,258 (assigned to NOVA Chemicals International SA). This apparatus, mounted on the reactor head, was a tube-in-shell condenser, with 25°C cooling water circulating over the outer tubing (controlled by a closed-system cooling bath), and the inner tubing connected to the reactor (process), allowing for the release of excess gas pressure via a back pressure regulator. The back pressure regulator was set to 140 psig, and this pressure was recorded on the second day of the reaction. The pressure setting of 140 psig was determined by referencing the pressure on a steam table of water heated to 175°C, and a pressure slightly higher than the pressure indicated on the steam table was selected to ensure that the liquid reached its temperature (high boiling point). Some pressure release was observed through a glass water bubbler attached to the outlet (vent) of the back pressure regulator. Slow bubbling (pressure release of excess CO2(g) due to oxalic acid decomposition) was observed only on the second day of the 48-hour reaction.

[0043] After 48 hours, the reactor was allowed to cool to room temperature, and excess carbon dioxide (due to oxalic acid decomposition) and nitrogen pressure were evacuated into a fume hood. When the purple slurry was stirred, a vigorous bubbling of carbon dioxide occurred. The purple solid was filtered through a Buchner funnel lined with three layers of qualitative filter paper to separate the blue mother liquor from the dark purple (almost black) solid. After passing through the solid, the solid was rinsed approximately five times with 400 mL of distilled water until the filtrate no longer showed a visible blue color. The solid was then dried overnight in a 90°C oven and then ground into small particles using a mortar and pestle.

[0044] <Firing> A portion of the crushed recovered product was loaded into a quartz boat, and the quartz boat was placed inside a quartz tube for calcination. The quartz tube was purged with bulk nitrogen (oxygen less than 10 ppm) at a flow rate of 30 sccm, and air was passed through a silicone oil bubbler from the outlet side of the tube to maintain an anaerobic atmosphere. The atmosphere inside the tube was purged with bulk nitrogen (oxygen less than 10 ppm) for 6 hours, and then the inlet bulk nitrogen was redirected through an oxygen trap (LabClear OxiClear® gas purifier) ​​and the tube was further purged with purified nitrogen (oxygen less than 1 ppm) for 12 hours. Calcination proceeded under the following heating conditions with a 30 sccm purified nitrogen flow: the temperature was raised from room temperature (approximately 20°C) to 600°C in 6.25 hours (1.6°C / min), held at 600°C for 2 hours, and then allowed to cool naturally.

[0045] Additional catalyst examples were prepared by changing the amount of starting material and modifying the general procedure as follows: The amount of catalyst 1.2:tantalum ethoxide was increased to 23.1 g, and during hydrothermal baking, the external control temperature was set to 185°C and the slurry was stirred at 150 rpm. Catalyst 1.3: During hydrothermal baking, the slurry was stirred at 20 rpm. Catalyst 1.4: Instead of preparing tantalum oxalate by digesting tantalum ethoxide with oxalic acid, a commercially available catalyst was used. Catalyst 1.5: Commercially available tantalum oxalate was used, and its amount was reduced to 1.94 times that of catalyst 1.1. The procedure is the same as that used for catalyst 1.6 and catalyst 1.5. Catalyst 1.7: (NH4)6Mo6TeO 24 ·7H2O (s) It was prepared in situ in an aqueous solution, rather than being isolated as a solid. Two-step pH adjustment was performed; the first step involved NH4OH (aq) The pH was then adjusted to approximately 7.5, and the second time, H2SO4 was used. 4(aq) The pH was then adjusted to approximately 5. Catalyst 1.8: The same procedure as for catalysts 1.5 and 1.6 was followed, but NH4OH (aq) Adjust the pH to approximately 5.0 once using (NH4)6Mo6TeO 24 ·7H2O (s)It was prepared on the spot. Catalyst 1.9: The same procedure as Catalyst 1.1 was followed, but the scale was increased by approximately five times.

[0046] Comparative example catalyst 2.1 was prepared according to the procedure outlined in Example 1 of U.S. Patent Publication No. 2010 / 0222623. Specifically, 20.9995 g of (NH4)6Mo7O 24 · 4H2O (s) It was dissolved in 150 mL of distilled water while stirring at 80°C. Te(OH) 6(s) 7.64g was dissolved in 85mL of distilled water while stirring at 80°C. Te(OH) 6(aq) The solution of (NH4)6Mo7O 24(aq) The solution was added all at once at 80°C to produce a colorless, transparent solution, which was then stirred at 80°C for 15 minutes. 4.5940 g of NH4VO4 was added to the MoTe solution at 80°C. 3(s) When added all at once, a bright orange solution was instantly produced. This solution was stirred at 80°C for 5 minutes, during which time a small amount of solid precipitate formed. The stirred orange mixture was then cooled to room temperature over 45 minutes. To the room temperature orange mixture, 11.742 mmol of colorless, transparent aqueous tantalum oxalate was added dropwise over 20 minutes to obtain a clear orange solution. The aqueous tantalum oxalate used was prepared in the same manner as outlined in Example 1 (e.g., Ta(OEt)). 5(l) (Prepared from aqueous oxalic acid digest of tantalum oxide precipitated from [the substance]).

[0047] The resulting orange mixture was evaporated over a vacuum of 650 mmHg while being heated at 50°C (through a heated water bath) and stirred at 500 rpm. An orange solid was observed almost midway through the evaporation process while the water was being removed. After all visible water had been removed, a pale orange solid was obtained, which was dried in an oven at 120°C for 4 hours to produce a dark orange solid, which weighed 34.8748 g when weighed with a mortar and pestle.

[0048] 34.8748 g of the entire crushed dark orange solid was loaded into a quartz boat and calcined in a quartz tube reactor. Before calcination, the quartz tube containing the solid to be calcined was purged with bulk nitrogen (oxygen less than 10 ppm) at a flow rate of 30 sccm, and the tube was maintained in an anaerobic atmosphere by passing air through a silicone oil bubbler from the outlet side of the tube. The atmosphere inside the tube was purged with bulk nitrogen (oxygen less than 10 ppm) for 6 hours, and then the inlet bulk nitrogen was redirected through an oxygen trap (LabClear OxiClear® gas purifier) ​​and the tube was further purged with purified nitrogen (oxygen less than 1 ppm) for 12 hours. Calcination proceeded under the following heating conditions with a 30 sccm purified nitrogen flow: the temperature was raised from room temperature to 600°C in 1 hour (approximately 10°C / min), held at 600°C for 2 hours, and then allowed to cool naturally.

[0049] After firing, the weight of catalyst 2.1, a black, hard sintered powder, was 26.8901 g, and the weight yield was 77.1%. It was noted that the outlet of the quartz tube was considerably covered with gray sublimated deposits. These deposits were considerably more abundant than those observed in any of the present inventions.

[0050] <Catalyst materials> Catalyst materials, including catalysts and support / support materials, were prepared using catalyst 1.1, catalyst 1.6, and comparative catalyst 2.1. Activity evaluations were performed along with physical characterization to determine which support or carrier was suitable for use in the catalyst material. Suitability was determined by catalytic testing of the catalyst material in an MRU reactor and by observing high ethylene selectivity in the initial stages (within 8 hours of the start of testing), e.g., selectivity for ethylene exceeding 89 mol% at an ethane conversion rate of approximately 50 mol%. The preparation of the catalyst materials is as follows:

[0051] Catalyst 1.1 was produced by mixing Catalyst 1.6 with synthetic amorphous silica, targeting a total weight product of 40 wt% Catalyst 1.6 and 60 wt% Support. The synthetic amorphous silica used in this example was obtained from PQ Corporation, product identifier CS6846;PD-10042, classified as a precipitate synthesis (precipitation from alkali silicate solution), and classified as CAS-No. 112926-00-8. Catalyst 1.6 (4.0375 g) and precipitated synthetic silica (6.0493 g) were suspended together in 35 mL of distilled water to form a slurry, which was heated to 100°C and stirred at 80 rpm via a motor-driven overhead Teflon® stirrer. Stirring and heating at 100°C were continued until sufficient water evaporated and a thick paste (viscosity of modeling clay) was formed, and then it was dried overnight in an oven at 90°C. After oven drying, the remaining material (9.6999g) was loaded into a quartz boat and inserted into the quartz tube of a split tubular furnace. The tube was sealed and purged overnight at room temperature with an atmosphere of unrefined nitrogen (oxygen concentration less than 10 ppm) at a flow rate of 14 sccm. Two hours before starting furnace heating, the purge was switched to refined nitrogen (for example, unrefined nitrogen was redirected through a LabClear OxiClear® gas purifier, an oxygen trap, to produce nitrogen with less than 1 ppm of oxygen). The flow rate of refined nitrogen was reduced to 5 sccm, and the furnace was heated to 500°C at a rate of 1.6°C / min, held at 500°C for 2 hours, and then cooled (heater off). The catalyst was removed and weighed (9.2891g, 95.8 mass yield). The sample was transferred to a 50 mL beaker, and a second calcination process was performed in air at 250°C for 2 hours, with both heating and cooling occurring at a heating rate of 2 hours, to produce catalyst material 1.1.

[0052] Specifically, catalyst 1.6 was mixed with synthetic amorphous silica, aiming for a total weight product of 40% by weight of catalyst 1.6 and 60% by weight of silica. The synthetic amorphous silica used in this example was obtained from Sigma-Aldrich Corporation, product number S5130, classified as fumed synthesis (produced by flame hydrolysis of silicon tetrachloride or similar), and classified as CAS-No. 112945-52-5. Fumed synthetic silica (6.0015 g) was mixed with 50 mL of distilled water to form silica gel, which was then transferred to a 50 mL beaker containing 4.0002 g of catalyst 1.6. The contents of the beaker were mixed with a spatula to produce a slurry, which was then heated to 100°C in an oil bath and stirred at 80 rpm via a motor-driven overhead Teflon stirrer. The beaker was stirred until sufficient moisture evaporated and a thick paste (with the viscosity of modeling clay) was formed, then heated at 100°C for approximately 3.5 hours, and subsequently removed from the oil bath. The beaker containing the paste was placed in a 90°C oven and allowed to dry overnight in a static state. After oven drying, 9.6906 g of material was recovered, the entire catalyst material was ground in a mortar and pestle, loaded into a quartz boat, and inserted into the quartz tube of a split tubular furnace. The tube was sealed and purged overnight at room temperature with an atmosphere of unrefined nitrogen (oxygen concentration less than 10 ppm) at a flow rate of 14 sccm. Two hours before starting furnace heating, the purge was switched to refined nitrogen (for example, unrefined nitrogen was redirected through a LabClear OxiClear® gas purifier, an oxygen trap, to produce nitrogen with less than 1 ppm of oxygen). The flow rate of purified nitrogen was reduced to 5 sccm, and the furnace was then heated to 500°C at a rate of 1.6°C / min, held at 500°C for 2 hours, and then cooled (heater off). The catalyst was removed and its weight was measured. The weight of catalyst material 1.2 after calcination was 9.4840g (96.2% mass yield). The sample (9.3224g) was transferred to a 50mL beaker and calcined in air at 250°C for 2 hours. After the second calcination, 9.4840g of catalyst material 1.2 was recovered.

[0053] Catalyst material 1.3 was produced by mixing catalyst 1.6 with aluminum silicate, targeting a total weight product of 40 wt% catalyst 1.6 and 60 wt% aluminum silicate. The aluminum silicate used in this example was obtained from Sigma-Aldrich, with product number 343358 and product name "Silica-Alumina Catalyst Support, Grade 135". Aluminum silicate is classified as an aluminum salt of silicate based on the CAS No. 1335-30-4 assignment. Catalyst material 1.3 was prepared starting from 4.0021 g of catalyst 1.6 and 5.9995 g of Sigma-Aldrich silica-alumina catalyst support, grade 135, following the procedure used for catalyst material 1.1. The weight after nitrogen calcination at 500°C was 9.8475 g (99.9% mass yield). After calcination in air at 250°C, the mass of the recovered catalyst material 1.3 was 9.8451 g (100.01 mass% yield).

[0054] Catalyst material 1.4 was produced by mixing catalyst 1.6 with α-alumina, aiming for a total weight product of 40 wt% catalyst composition and 60 wt% support. The α-alumina used in this example was obtained from Saint-Gobain and is product name: DENSTONE® 99. DENSTONE 99 is aluminum oxide with a concentration of over 99 wt%, CAS No. 1344-28-1. Before application, the α-alumina of DENSTONE 99 was pulverized and passed through a #60 sieve to confirm that the particle size was less than 250 μm. Catalyst material 1.4 was prepared as described above for catalyst material 1.1, starting from 4.0013 g of catalyst 1.6 and 5.9998 g of pulverized α-alumina. The weight after nitrogen calcination at 500°C was 9.9876 g (99.7% mass yield). After calcination in air at 250°C, the mass of the recovered catalyst material 1.4 was 9.8959 g (100.01 mass yield).

[0055] Catalyst material 1.5 was produced by mixing catalyst 1.6 with anatase-type titania, targeting a total weight product of 40 wt% catalyst 1.6 and 60 wt% anatase-type titania. The anatase-type titania used in this example is Sigma Aldrich product number 232033, CAS number 1317-70-0. Catalyst 1.5 was prepared starting from 4.0004 g of catalyst 1.6 and 5.9999 g of anatase-type titania, following the procedure described above for catalyst 1.1. After nitrogen calcination at 500°C, the weight of catalyst material 1.5 was 9.6920 g (99.7% mass yield). After air calcination at 250°C, the mass of recovered catalyst material 1.5 was 9.6605 g (99.7% mass yield).

[0056] The following catalyst supports (carriers) were found to be incompatible with the catalyst upon mixing and were deemed unsuitable for use in catalyst materials. Incompatibility was determined by catalytic testing of the catalyst materials in an MRU reactor and observation of significant loss of ethylene selectivity (e.g., less than 90 mol% selectivity for ethylene at approximately 50 mol% ethane conversion). In some cases, if the resulting catalyst material is highly inert, the catalyst composition is also considered incompatible with the support.

[0057] Catalyst material 2.1 was produced by mixing catalyst 1.6 with silicon carbide, aiming for a total weight product of 40 wt% catalyst 1.6 and 60 wt% silicon carbide. The silicon carbide used in this example was product code: SC55167, 13 wt% SiO2, remainder SiC (CAS-No. 409-21-2), obtained from Saint-Gobain. Before application, the silicon carbide was pulverized and passed through a #60 sieve to confirm that the particle size was less than 250 μm. Catalyst material 2.1 was prepared starting from 4.0017 g of catalyst 1.6 and 6.0005 g of pulverized silicon carbide, following the procedure described above for catalyst material 1.1. The weight after nitrogen calcination at 500°C was 9.8806 g (99.5% mass yield). After firing in air at 250°C, the mass of the recovered catalyst material 2.1 was 11.9546 g (mass yield 121.0%).

[0058] Catalyst material 2.2 was produced by mixing catalyst 1.6 with colloidal alumina, targeting a total weight product of 40 wt% catalyst 1.6 and 60 wt% support. The colloidal alumina used in this example was Alfa Aesar's Cat No. 12733, containing 20 wt% Al2O3 dispersed in water. Catalyst 2.2 was prepared starting from 4.0418 g of catalyst 1.6 and 30.0648 g of 20 wt% Al2O3, following the procedure described above for catalyst 1.1.

[0059] Catalyst material 2.3 was produced by mixing catalyst 1.1 with boehmite aluminum hydroxide, targeting a total weight product of 40 wt% catalyst 1.1 and 60 wt% boehmite aluminum. The boehmite aluminum hydroxide used in this example was obtained from Honeywell UOP, product name Versal V-250 (No. 86251), described as low-density pseudoboehmite alumina (wt% < 95%; CAS-No. 1344-28-1). For synthesis, 4.0263 g of catalyst 1.1 and 6.0622 g of boehmite aluminum hydroxide were placed in a 50 mL beaker, and a sufficient amount of distilled water was added to form a suspension to form a slurry. The beaker containing the slurry was placed in an oil bath, heated to 100°C, and stirred at 85 rpm via a motor-driven overhead Teflon stirrer. The beaker was stirred until sufficient moisture evaporated and a thick paste (with the viscosity of modeling clay) was formed (approximately 3 hours), then heated to 100°C and removed from the oil bath. The beaker containing the paste was placed in a 90°C oven and allowed to dry overnight in a static state. After oven drying, the recovered material was loaded into a quartz boat, placed in a muffle furnace, and heated in air to 350°C over 4 hours, then fired in air by maintaining the temperature at 350°C overnight, followed by natural cooling (heater off). The recovered solid was used as catalyst material 2.3.

[0060] Catalyst material 2.4 was produced by mixing catalyst 1.6 with calcium titanate, aiming for a total weight product of 40 wt% catalyst 1.6 and 60 wt% calcium titanate. The calcium titanate used in this example is Goodfellow Corporation product code: CA546, classified as 80-100 wt% calcium titanium oxide (CaTiO3), and classified as CAS-No. 12049-50-2. Catalyst material 2.4 was prepared starting from 3.9986 g of catalyst material 1.6 and 6.0013 g of calcium titanate powder, following the procedure described above for catalyst material 1.1. After nitrogen calcination at 500°C, the weight was 9.7932 g (99.2% mass yield). After air calcination at 250°C, the mass of the recovered catalyst material 2.4 was 9.7813 g (100.02% mass yield).

[0061] Catalyst material 2.5 was produced by mixing catalyst 1.6 with zirconia powder, targeting a total weight product of 40 wt% catalyst 1.6 and 60 wt% support. The zirconium(IV) oxide used in this example is Sigma Aldrich product number 204994, CAS No. 1314-23-4. Catalyst material 2.5 was prepared starting from 4.0001 g of catalyst 1.6 and 6.0015 g of zirconia, following the procedure described above for catalyst material 1.1. After nitrogen calcination at 500°C, the weight was 9.6723 g (99.3% mass yield). After air calcination at 250°C, the mass of the recovered catalyst material 2.5 was 9.6725 g (101.1% mass yield).

[0062] Catalyst material 2.6 was produced by mixing catalyst 1.6 with colloidal zirconia, targeting a total weight product of 40 wt% catalyst 1.6 and 60 wt% colloidal zirconia. The colloidal zirconia used in this example was Alfa Aesar's Cat No. 40124, containing 20 wt% ZrO2 dispersed in water. Catalyst material 2.6 was prepared starting from 4.0371 g of catalyst 1.6 and 30.0044 g of 20 wt% ZrO2 colloidally dispersed in water, following the procedure described above for catalyst material 1.1.

[0063] <Performance> The prepared catalysts and catalytic materials were tested for their physical properties and their ability to convert ethane to ethylene. Catalyst performance was evaluated for 35% and 50% conversion temperatures, as well as the corresponding selectivity to ethylene. Further testing was conducted on the robustness of the catalysts and catalytic materials. Specifically, since many oxidative dehydrogenation catalysts have been shown to decrease in activity, selectivity, or both over time, testing was performed to evaluate the impact on conversion rates and selectivity over longer periods. Finally, the resilience of the catalysts and catalytic materials to low residual oxygen levels and their selectivity to acetic acid were evaluated.

[0064] <mru> The ability of the catalysts and catalytic materials described herein to participate in the oxidative dehydrogenation reaction of ethane was tested using a microreactor unit (MRU) 100, whose cross-section is shown in Figure 1. The MRU 100 consists of a vertically oriented reactor tube 1 formed from stainless steel SWAGELOK® tubing with an outer diameter of 0.5 inches, an inner diameter of 0.4 inches, and a length of 13.4 inches, surrounded by a two-zone electric heater 2 or a tubular furnace, and connected to the upper and lower tubes via SWAGELOK connectors 6. The catalyst bed 3 (gray shaded), containing the catalyst or catalytic material located in or near the center (along the length) of the reactor tube, is fixed in place by packing 4 (hatched shaded), containing glass wool, which is in contact with the upper (4a) and lower (4b) boundaries of the catalyst bed. A 6-point WIKA Instruments Ltd. K-type thermocouple 5 with an outer diameter of 0.125 inches was inserted along the length from the center of the reactor tube 1 to measure the temperature inside the catalyst bed. To control the temperature inside the reactor, the output to electric heater 2 was controlled using a temperature input from thermocouple 5. The six points indicated by the hollow circle are spread along the length of reactor tube 1, with points 3 and 4 located within the catalyst bed 3. A room-temperature stainless steel condenser was placed downstream of the reactor to collect the water / acetic acid condensate. The gaseous product flow was either discharged or sent to gas chromatography (GC; Agilent 6890N gas chromatograph, Chrom Perfect-Analysis, version 6.1.10 used for data evaluation) via a sampling loop (not shown).

[0065] To prepare catalysts and catalyst materials for testing in the MRU, the catalyst or catalyst material was loaded into a 1-inch round mold and pressed with a compression force of 12 tons, held under this pressure for at least 10 seconds. The resulting pressed pack of catalyst or catalyst material was then finely crushed using a mortar and pestle. The crushed catalyst or catalyst material was sieved to collect particles with a size of 425 μm to 1000 μm, which were loaded for testing in the MRU.

[0066] In a standard catalyst test, 2.00 g of catalyst, sieved from a pulverized press catalyst with particle sizes ranging from 425 μm to 1000 μm, was physically mixed with silica sand until the total volume of the mixture reached 6 ml. After loading the catalyst bed into the reactor and connecting it to the MRU (Measuring Unit) apparatus, a premixed feed gas containing 20 mol% ethane, 10 mol% oxygen, and 70 mol% nitrogen (ethane-to-oxygen molar ratio of 1 / 0.5) was fed from the upper pipe 8 (indicated by the hollow arrow) through reactor pipe 1, and the effluent gas exited through the lower pipe 9. The premixed feed was prepared using a gas mixing apparatus and a calibrated mass flow controller (not shown) was used. An outlet pressure of 20 psig was maintained using a back pressure regulator (not shown). In all catalyst test experiments, the time taken was 5.46 h. -1 To achieve a constant weight-force spatiotemporal velocity (WHSV), the flow rate of the premixed feed gas was controlled to 152 standard cubic cm (sccm). Here, WHSV is defined as the mass flow rate of the feed gas to the reactor divided by the weight of the catalyst in the catalyst bed. The gas exiting the reactor was analyzed by GC (Agilent 6890N gas chromatograph, Chrom Perfect-Analysis, version 6.1.10 used for data evaluation) to determine the percentages of various hydrocarbons (e.g., ethane and ethylene), and optionally other gases such as O2, CO2, CO, and acetylene. The results were used to calculate the conversion rate and selectivity defined above. Temperature was monitored in real time at all six points, and the average temperature at points 3 and 4 (inside the catalyst bed) was used for plotting the conversion rate against temperature.

[0067] Several catalysts were subjected to the modified MRU setup and operating conditions. Specifically, reactor tube 1 was 15 inches long, and the catalyst packing consisted of 2.00–4.00 g of pulverized press catalyst in a catalyst bed volume of 6 ml. Furthermore, the premixed feed gas entering reactor tube 1 was 35 mol% ethane, 17.5 mol% oxygen, and 47.5 mol% nitrogen (ethane to oxygen molar ratio of 1 / 0.5), the reactor was operated at a pressure close to the ambient reactor outlet pressure, and the internal reactor pressure due to dP from the reactor bed load was recorded as less than 3 psig. 2.79h -1 To achieve a constant weight-force space-time velocity (WHSV), the flow rate of the premixed feed gas was controlled between 76 and 152 standard cubic cm (sccm) depending on the weight-filled volume. The modified method resulted in a higher conversion temperature, which is not surprising considering the pressure difference compared to the standard method described above. The conversion rate and selectivity limits described herein are based on a 15-inch reactor tube with a 0.4-inch inner diameter, a feed gas containing 20 mol% ethane, 10 mol% oxygen, and 70 mol% nitrogen, and a WHSV of 5.46 h -1 This is intended to represent the limits measured using a standardized methodology under conditions where the device is held and the pressure is maintained at 20 psig.

[0068] Table 1 below shows the MRU catalyst test data for catalysts 1.1 to 1.9 and catalyst 2.1, in which the temperature was increased in stages to determine the catalyst performance. GC data regarding the product gas composition was collected at each temperature interval. Then, a linear algebraic equation was constructed using the raw GC data, and the results for ethane conversion rates (35 mol% and 50 mol%) and corresponding ethylene selectivity (mol%) are summarized in the table below.

[0069] The data in Table 1 shows that the conversion temperatures of most catalysts were significantly lower than those of Comparative Example 2.1, indicating low activity in Comparative Example 2.1, as the conversion rate did not reach 35 mol% or 50 mol% before the reactor temperature reached 500°C. With the exception of catalysts 1.2 and 1.7, all examples showed ethylene selectivity exceeding 90% even at a conversion temperature of 50 mol%. Furthermore, the results for catalyst 1.9 indicate that scaling up the synthesis to supply larger quantities does not negatively impact performance; in fact, catalyst 1.9 performed better than catalyst 1.1, with a lower conversion temperature and similar ethylene selectivity. Catalysts 1.1 and 1.5 were evaluated using both the standard MRU method and the modified method, and while there was no effect on selectivity, the conversion temperature was 14°C to 39°C higher with the modified method. Asterisks indicate samples evaluated only with the modified method.

[0070] [Table 1]

[0071] Catalysts 1.1 and 1.6 were selected, and appropriate supports were evaluated. Suitable or compatible supports were evaluated by determining the effect of the catalyst-support combination on selectivity and conversion rate. MRU testing of the catalyst material was performed according to the standard test procedure described above. Specifically, 4.00 to 5.00 g of pressed catalyst material with particle sizes ranging from 425 μm to 1000 μm was physically mixed with silica sand to a total volume of 6 to 8 mL. If the density of the catalyst material was too low, and 5 g of catalyst material reached a volume of 6 mL, no sand was added. If the density of the catalyst material was too low, and 5 g of catalyst exceeded 6 mL, a maximum amount of 8 mL of catalyst was loaded, and the WHSV specification of 5.47 h was met. -1 The flow rate was adjusted to maintain the specified value. Since all catalyst materials were prepared with 40% by weight of catalyst, the weight of catalyst packed into the MRU test apparatus ranged from 1.60 to 2.00 g. In all catalyst test experiments, 5.46 h -1 To achieve a constant weight-based spacetime velocity (WHSV), the flow rate of the premixed supply gas was controlled between 126 and 152 standard cubic centimeters (sccm) depending on the weight-filled volume.

[0072] As will be apparent to those skilled in the art, the same reactor dimensions, feed composition, operating pressure, and WHSV 5.47h are as described above. -1 As long as measurements can be obtained using the specified method, the use of variable catalyst amounts and total catalyst bed volumes, as described, will not significantly affect the measured values ​​of conversion rate and selectivity. The limits of conversion rate and selectivity described herein and claimed are measured under the conditions described.

[0073] The data in Table 2, collected by MRU using the standard catalyst tests described above, shows that support materials containing precipitated silica, fumed silica, aluminum silicate, α-alumina, anatase-type titania, and zirconia powder yielded the best results, maintaining conversion and selectivity below 431°C and above 87%, respectively. In contrast, support materials containing silicon carbide, colloidal alumina, boehmite aluminum, calcium titanate, and colloidal zirconia appeared unsuitable due to significantly reduced selectivity.

[0074] [Table 2]

[0075] <Robustness> New catalysts typically exhibit robust activity, which generally decreases over time. While we don't want to be constrained by theory, this effect may be due to the sublimation of elements within the catalyst, resulting in changes to its structure and composition. Catalysts with more stable structures and phase compositions can maintain high conversion rates and selectivity over time, extending their lifespan and making them suitable for commercial processes.

[0076] Robustness tests were performed on catalysts and catalyst materials in the MRU using the standard test conditions described above for catalyst packing amount, feed gas composition, pressure, and WHSV. Gas chromatography (GC) monitoring of the effluent gas was used to adjust the temperature to meet the specified criteria (either the 50% conversion temperature or the residual oxygen level (mol%)). The determination of the 50% conversion temperature for each tested catalyst material was used as an estimate of the temperature required to achieve a 50% conversion rate. Due to inherent variability (approximately 1-3 degrees), the conversion rate at the set temperature was not always 50%. In the catalyst robustness tests, the temperature was set to achieve a 50% conversion rate. If the conversion rate steadily decreased and plateaued, the temperature was adjusted to achieve a 50% conversion rate. Test runs were conducted for a maximum of 48 hours (up to 144 hours).

[0077] In the robustness tests of catalyst materials, a temperature was set and maintained throughout the entire operating time. Test runs proceeded for up to 48 hours (up to 144 hours), but were stopped when the conversion rate or selectivity dropped to an unacceptable level (e.g., catalyst material 2.1).

[0078] Figure 2 shows the effect of long-term testing of catalyst 1.1. This result was achieved over approximately 144 hours of operating time (TOS). The 50% conversion temperature of catalyst 1.1 was predetermined to be 443°C (Table 1). Based on this predetermined temperature, a similar temperature of 440°C was used for calibration. During the calibration period (approximately 15 hours), the catalyst showed a slight decrease in conversion rate (upper figure), but there was no significant change in selectivity (lower figure). The temperature was then increased to 448°C (indicated by the arrow) to obtain a 50% conversion rate, and this temperature was maintained for a period. Again, the catalyst showed a slight decrease in conversion rate over time, but the conversion rate stabilized as the curve flattened. Selectivity remained essentially constant throughout. WHSV was 5.47h -1 This remained constant throughout. These results indicate that catalyst 1.1 is stable and can maintain its activity and selectivity over time.

[0079] Figure 3 shows the effects of long-term testing of catalyst 1.6. These results were achieved by maintaining a temperature of 442°C throughout the test, with a total operating time (TOS) of approximately 96 hours. The catalyst showed no significant changes in either conversion rate (upper figure) or selectivity (lower figure). These results demonstrate that catalyst 1.6 is stable and can maintain its activity and selectivity over time at a temperature of 442°C.

[0080] Figure 4 shows the effect of long-term testing of catalyst 1.6 under low residual oxygen conditions. This result was achieved over approximately 120 hours of operation (TOS). The starting temperature for the robustness test of catalyst 1.6 was set to 470°C, the temperature at which the residual oxygen content in the effluent was approximately 0.27 mol%. The conversion rate (upper figure) slowly decreased over approximately 87 hours until the temperature was changed to 455°C (indicated by the arrow) to obtain a conversion rate of approximately 50%. The selectivity (lower figure) remained essentially constant throughout, and increased slightly after the temperature was lowered to 455°C. This result indicates that catalyst 1.6 is stable and can maintain its activity and selectivity over time. Furthermore, catalyst 1.6 appears to be resilient even at low residual oxygen levels. This is important because many known catalysts have been shown to irreversibly deactivate at low oxygen levels.

[0081] Similar results were observed with catalyst 1.5 (not shown), where the conversion rate decreased slightly over 120 hours, but the selectivity remained at approximately 91% without significant change. The comparative catalyst, catalyst 2.1, did not reach a conversion rate of 35% even at temperatures exceeding 500°C, and therefore was not included in the robustness test (Table 1).

[0082] To demonstrate the effect of catalyst-support combinations on conversion rate and selectivity, a robustness test was conducted on catalyst materials formed from catalyst 1.6. Figure 5 shows the effect of the long-term test of catalyst material 1.1. The results for catalyst material 1.6 are included for comparison, with a time of operation (TOS) of approximately 48 hours. The starting temperature for the robustness test of catalyst material 1.1 was set to 455°C, the temperature at which a conversion rate of approximately 50% (residual oxygen content of 2.06 mol%) is achieved. The conversion rate (see figure above) remained essentially constant throughout, with minimal deviation (±1~2°C), similar to catalyst 1.6. The selectivity gradually increased over time, from approximately 88% to approximately 90%. This result indicates that precipitated silica is suitable for use as a support, demonstrating good conversion rate and selectivity maintained at temperatures above 400°C for at least 48 hours.

[0083] Figure 6 shows the effects of long-term testing of catalyst material 1.2. The results for catalyst material 1.6 are included for comparison, with a total operating time (TOS) of approximately 48 hours. The starting temperature for the robustness test of catalyst material 1.2 was set to 450°C, which results in a conversion rate of approximately 50% (residual oxygen content of 2.40 mol%). The conversion rate (see figure above) remained essentially constant throughout, with minimal deviation (±1-2°C), similar to catalyst 1.6. The selectivity gradually increased over time, from approximately 88% to approximately 90%. This result indicates that fumed silica is suitable for use as a support material.

[0084] The results for catalyst materials 1.3, 1.4, and 1.5 showed similar results in terms of robustness, but the conversion rate decreased slightly before stabilizing over time. The temperature used was slightly high, set to 460°C, which may be the cause of the decrease. Despite the slight decrease, these catalyst materials demonstrate the ability to maintain relatively high selectivity (approximately 90%) even at temperatures above 450°C. Operating at lower temperatures, such as 430°C, may result in a more stable conversion rate and higher selectivity.

[0085] In contrast, catalyst materials 2.1, 2.3, 2.4, and 2.5 showed poor performance, with conversion rates significantly decreasing or selectivity dropping to a low level of approximately 65% ​​during testing. The overall results of the robustness tests are summarized in Table 3 below.

[0086] [Table 3]

[0087] <Production of Acetic Acid> Acetic acid selectivity was determined by performing an MRU test for a sufficient period (e.g., 1–5 days) to collect aqueous condensate in a condenser downstream of the MRU. After collecting the condensate samples, the samples were subjected to liquid GC analysis (Agilent 6890N gas chromatograph, Chrom Perfect-Analysis, version 6.1.10 used for data evaluation). For liquid GC analysis, 300–450 mg of liquid sample was transferred to a scintillation vial. Next, 25 mg of isopropanol (IPA) was added as an internal standard. Furthermore, 18–20 mL of distilled H2O was added to dilute the sample. The prepared samples were then transferred to GC vials and set up in sequence for testing using an autosampler. GC analysis was performed using a split injection method with a temperature program and FID detector. In addition, a set of three calibration standards was duplicated for the relative response coefficient used to calculate the acetic acid content in the sample.

[0088] Table 4 below shows the corresponding acetic acid levels (wt%) measured by GC analysis in the aqueous condensate products obtained from MRU long-term robustness test data for catalysts 1.1, 1.5, and 1.6, as well as catalyst materials 1.1 to 1.5, 2.3, and 2.5. Aqueous condensate samples were collected on the specified days, and sufficient amounts of liquid were collected and subsequently quantified by GC analysis. Due to the small scale of the MRU apparatus, it was necessary to measure acetic acid using GC analysis of the aqueous condensate. In commercial-scale applications, the amount of aqueous acetic acid is sufficiently large to measure the acetic acid level with high accuracy using mass balance calculations for the gaseous product flow. The use of GC analysis allowed for accurate measurement of the acetic acid level (wt%) of the entire reactor effluent. Note that the selectivity calculation does not include acetic acid components that were not part of the gas phase.

[0089] [Table 4]

[0090] The results showed that the acetic acid level did not exceed 3.5% by weight, although there was some daily variation. This is a fairly low value, especially considering that the measurements were taken when the conversion rate level was close to 50%. Many ODH catalysts known in this art exhibit acetic acid selectivity in the range of 5–12% by weight.

[0091] <Physical Characterization> The physical properties of the generated catalyst and catalyst material were evaluated, and the molar ratio of the elements present, the phase composition (particularly regarding the M1 phase and amorphous phase), and the particle size were determined.

[0092] <sem> Scanning electron microscope (SEM) images were acquired using a JSM-IT300LV InTouchScope™. Samples were prepared on aluminum studs using double-sided carbon tape. These samples were then scanned on the SEM stage. Figure 7 includes SEM images (10,000x magnification) of catalysts 1.1–1.6 and catalyst 2.1. The difference in appearance of catalyst 2.1 compared to catalysts 1.1–1.6 suggests a different crystal structure, which may be the cause of the significant difference in conversion rate and selectivity. Figure 8 includes SEM images (10,000x magnification) of new and used catalyst materials 1.1, 1.4, and 1.5, as well as new catalyst materials 1.2 and 1.3.

[0093] <sem-eds> Energy-dispersive X-ray spectroscopy (EDS) was performed using a JEOL JED-2300 DRY SDD EDS detector. Samples were sent to SEMx Incorporated for EDS analysis, and the molar ratios of elements present in the catalyst and catalytic material were determined. The tested catalyst and catalytic material samples were finely ground to reduce particle size and obtain a homogeneous mixture. These were then loaded into an EDS stub for SEM analysis. EDS was used for elemental analysis and surface inspection. EDS is a trace analysis technique that semi-quantitatively analyzes the elemental properties of the sample surface (e.g., top 1-3 microns). SEM is used to inspect surface morphology at magnifications of 20x to 100,000x. EDS instruments can detect elements with atomic numbers greater than or equal to sodium, but also have light element capabilities, allowing detection of carbon, nitrogen, oxygen, and fluorine. The lower limit of the estimated detection limit for any element is generally about 0.2-0.5 wt%.

[0094] To determine the elemental composition, EDS evaluation was performed on the prepared catalysts and catalyst materials. The molar ratios were determined using the EDS elemental mass weight percent of the detected elements, as shown in Figure 5. Catalysts 1.1 to 1.6 differ significantly from comparative example catalyst 2.1. Compared to the molybdenum component, V is significantly higher and Te is significantly lower. Tantalum levels are typically higher, except for catalysts 1.5 and 1.6.

[0095] [Table 5]

[0096] EDS measurements were also performed on the molar ratio of the catalyst materials. The results are shown in Table 6. Additional elements such as Si, Al, Na, and Mg, which are thought to contribute from the support material, are also indicated in the chemical formulas. The tendency of some catalysts to lose activity or selectivity over time may be due to changes in composition under the conditions of the oxidative dehydrogenation process. Several catalyst materials were re-evaluated by EDS after being used in robustness tests to check for significant changes in composition (marked "used"). No significant changes were observed in the four elements Mo, V, Te, and Te. Low levels of iron in the used catalyst materials may be due to iron leaching from the reactor tubes.

[0097] [Table 6]

[0098] <SEMによるPSD> Samples were sent to SEMx Incorporated for particle size analysis using a scanning electron microscope (SEM), model JEOL-JSM300LV. Using the SEM, particles in the sample were observed and counted to obtain a particle size distribution (PSD). For PSD measurements, photographs were taken at different magnifications using the SEM instrument. Measurements were performed on 400–800 particles at different magnifications to cover the size range (statistical population). Size was measured in micrometers, representing the longest dimension of the particle. SEM-based PSD is a suitable method for analyzing samples where particles are aggregated (clumped together). This is because the analyst can visually confirm this through the microscope and make the prudent decision to measure individual particles rather than aggregates. Statistics and analysis are based on the total count measured by the SEM.

[0099] Table 7 shows the particle size distribution results for catalysts 1.1 to 1.6 and catalyst 2.1, and Table 8 shows the particle size distribution results for catalyst materials 1.1 and 1.2.

[0100] [Table 7]

[0101] [Table 8]

[0102] <Pore volume, BET surface area analysis, BJH pore size distribution analysis> Gas adsorption manometry was used to determine the nitrogen adsorption isotherm at the temperature of liquid nitrogen (approximately 77K). The amount of adsorbed gas was evaluated by measuring the change in gas pressure. The isothermal nitrogen adsorption process was measured, and the surface area and volume were calculated by applying various theories / equations.

[0103] The total pore volume was calculated by incorporating nitrogen gas at a relative pressure P / P0 = 0.99.

[0104] The specific surface area (m²) of the solid sample was determined by applying Brunauer-Emmett-Teller (BET) analysis. 2 The volume ( / g) was quantified. BET evaluation was performed by multilayer adsorption of nitrogen and measured as a function of relative pressure. Since the shape of isotherms can differ greatly depending on the solid, it is difficult to compare them. By applying BET theory, the so-called single-layer capacity can be determined from the multilayer nitrogen adsorption experiment, allowing for a more quantitative comparison of the surface area of ​​solids. The single-layer capacity represents the total specific surface area and includes both the external area and pore area of ​​porous solids.

[0105] The Barrett-Joyner-Halenda (BJH) method is used in the Kelvin model (cm) for pore filling. 3 The pore size (Å) distribution was calculated from adsorption isotherms experimentally collected using ( / g·A). This technique characterizes the pore size distribution independently of the external area due to the particle size of the sample and can be applied to mesopores and small macropores.

[0106] Nitrogen physicoadsorption experiments were conducted using TriStar (Micromeritics Instruments), and samples were analyzed by nitrogen adsorption at 77K. The samples were loaded into a physicoadsorption cell and degassed at 200°C for 1 hour before the adsorption experiment.

[0107] Table 9 shows the measurement results for the surface area and pore volume of catalysts 1.6 and 2.1.

[0108] [Table 9]

[0109] <xrd> X-ray diffraction (XRD) data were collected using the PANalytical Aeris X-ray diffractometer at SEMx Incorporated. This data was used to determine the phase composition present in the prepared catalyst. The diffractometer consists of three basic elements: an X-ray tube, a sample holder, and an X-ray detector. X-rays are generated in a cathode ray tube (Cu source with Kα rays = 1.5418 Å) and irradiated onto the sample. By rotating the sample and detector, the intensity of the reflected X-rays is recorded, and a characteristic X-ray spectrum is obtained. When the incident X-rays reflected from the sample satisfy the Bragg equation (nλ = 2dsinθ), constructive interference occurs, resulting in an intensity peak (y-axis). The X-ray diffractometer is set up so that the sample rotates at an angle θ within the path of the X-ray beam, and the X-ray detector is mounted on an arm to collect the diffracted X-rays, rotating at an angle of 2θ from approximately 5° to 70° (x-axis).

[0110] Qualitative XRD analysis and Rietveld refinement were performed using HighScore Plus XRD analysis software. The samples were finely ground to reduce particle size and obtain a homogeneous mixture. These mixtures were then loaded into an XRD sample holder, and XRD spectra were acquired. The results of Rietveld refinement were combined with the results from Highscore Plus and EDS for qualitative and quantitative analysis.

[0111] <Determination of amorphous content> The weight percentage of the amorphous content was determined by an external standard. Using the external standard phase, the intensity constant K factor of the instrument was determined. Corundum was used as the external standard and measured with the same instrument configuration immediately after measuring the unknown sample. The K factor approach is described in O'Connor and Raven: 1988, Powder Diffraction, 3(1), pages 2-6. For each sample, in order to assign a weight percentage to the amorphous content, it was necessary to determine the weight percentage of the crystalline MoTeVTaO orthorhombic phase. The crystallinity (DOC) method was used to determine the amount of the amorphous phase based on the assumption that the total intensity of the area by each component in the analysis contributes to the entire diffraction pattern. The crystallinity is calculated as follows from the total area of the defined crystalline and amorphous components: DOC = crystalline area / (crystalline area + amorphous area) In the formula, the weight fraction of the amorphous material can be calculated as follows: W 非晶質 = 1 - DOC

[0112] ortho MoTeVTaO x Since the phase contributes to the crystalline area, it was necessary to quantify it in order to determine the amorphous area. To compensate for the fact that the effects vary depending on the material and background, some constants required for the DOC method were calibrated using a sample of the orthorhombic Pba2 MoVTeNbO x phase. In a sample containing the MoTeVTaO x orthorhombic Pba2 phase, the weight percentage of this phase was semi-quantitatively determined based on the MoVTeNbOx calibration.

[0113] <Determination of M1 phase content> MoTeVTaO x The orthorhombic Pba2 phase (also called the M1 phase in the literature) was fitted using the literature crystal structure data of compounds that are different but crystallographically similar. This is because their orthorhombic Pba2 crystal phases matched. See DeSanto.P, Jr & Buttrey, D. & Grasselli, R. & Pyrz, W. & Lugmair, C. & F, Jr & Vogt, Thomas & Toby, Brian., (2006), Topics in Catalysis 38: 31 - 40 ( "DeSanto"). Lattice parameters: a = 21.14(2) Å, b = 26.66(3) Å, c = 4.008 Å

[0114] <Comparative raw data analysis> The Rietveld refinement for the identification of Catalysts 1.1 to 1.6 and Catalyst 2.1, and the weight percentages related to the identified phases are shown in Table 10. The 9 - digit code below the chemical formula of the phase represents the corresponding reference code in PDF - 4+2020. Phase (TeO) 0.43 ((Mo 4.08 V 0.70 Ta 0.22 )O 14 ) corresponds to the phase identified in DeSanto. (TeO) 0.43 ((Mo 4.08 V 0.70 Ta 0.22 )O 14 ) The M1 phase represented by was not detected in Catalyst 1.2 and was significantly lower in Catalyst 2.1 synthesized according to the method disclosed in US Patent Publication No. 2010 / 0222623. From the perspective of the performance results, this result indicates that a significant amount of the M1 phase is essential to achieve high conversion and selectivity even at temperatures above 400°C. Furthermore, the most active catalysts contain at least 26.9 of the amorphous phase, and most examples contain 34.2 - 48.9 of the amorphous phase.

[0115]

Table 10

[0116] The Rietveld refinements for phase identification of catalyst materials 1.1 to 1.5, and the weight percentages associated with the identified phases, are shown in Table 11 below. The 9-digit code below the chemical formula of each phase represents the corresponding reference code in PDF-4+2020. Phase (TeO) 0.43 ((Mo 4.08 V 0.70 Ta 0.22 )O 14 This corresponds to the phase identified by DeSanto.

[0117] As a result, it is suspected to be phase M1 (TeO). 0.43 ((Mo 4.08 V 0.70 Ta 0.22 )O 14 The M1 phase content, while decreased compared to catalyst 1.6, is still higher than that of comparative catalyst 2.1 (see Table 10). This suggests that catalyst materials having at least 2.5% by weight of the M1 phase provide good conversion and selectivity at temperatures above 400°C. Furthermore, using the catalyst support / carrier combinations shown in Table 2 with catalysts 1.1, 1.2, 1.4, and 1.5 is unlikely to reduce the M1 phase to a level that impairs conversion and selectivity.

[0118] [Table 11]

[0119] Table 12 shows the Rietveld refinement for phase identification and the weight % associated with the identified phase for the catalyst materials selected before and after the MRU test. The 9-digit code below the chemical formula of the phase represents the corresponding reference code in PDF-4+2020. Phase (TeO) 0.43 ((Mo 4.08 V 0.70 Ta 0.22 )O 14 This corresponds to the phase identified by DeSanto. These results indicate that the M1 phase does not change significantly over time, which may explain the robustness exhibited by these catalytic materials.

[0120] [Table 12]

[0121] Figure 9 shows the XRD spectra (22.2) of catalysts 1.1, 1.3, 1.4, 1.5, 1.6, and comparative catalyst 2.1. o The plots (normalized by the nearest peak) are shown. For catalysts 1.1, 1.3, 1.4, 1.5, and 1.6 (composite), the relative peak intensities and 2θ angle ranges of the peaks identified in Figure 9 are shown in Table 13. The peaks correlate to a general pattern determined by the crystal structure. Major peaks include those around 22.2°, 26.7°, and 28.3°, which show maximum intensity at least 100%. Other notable peaks include those around 7.8°, 9.0°, 22.9°, and 25.0°. Catalyst 2.1 has some similarities but lacks the peaks around 7.8° and 9.0°.

[0122] [Table 13] TIFF0007854448000016.tif250167

[0123] Figure 10 shows plots of the XRD spectra of catalyst materials 1.1, 1.2, 1.3, 1.4, and 1.5. As can be seen from the figure, the characteristic patterns change as a result of adding the support / carrier material. The major peaks around 22.2°, 26.7°, and 28.3° are still visible, as are the peaks around 7.9° and 9.0°. Comparing the XRDs of new and used catalyst materials 1.1, 1.3, and 1.4, slight changes in the patterns were observed (data not shown), and the relevant peaks were still present.

[0124] <ftir> Fourier transform infrared spectroscopy (FTIR) is a technique used to obtain the infrared (IR) spectrum of a solid or liquid sample by irradiating the sample with monochromatic light and measuring its absorbance over a range of wavelengths. FTIR can be used as a fingerprinting technique to superimpose the IR spectrum of an unknown sample onto that of a known sample, or to identify characteristic absorptions representing specific types of molecular bonds (such as C=O, OH, NH, CH, CO, SO, S=O, etc.). For FTIR scanning, solid samples were prepared using the pressed KBr pellet technique. The instrument used in-situ was a Bruker Tensor 27 FTIR spectrophotometer with a laser operating at 633 nm. FTIR profiles for catalysts 1.1-1.6 and 2.1 are shown in Figure 11. [Industrial applicability]

[0125] This disclosure relates to a catalyst useful for the oxidative dehydrogenation of ethane. This catalyst comprises molybdenum, vanadium, terylium, and tantalum, and exhibits good conversion rate and selectivity to ethylene at temperatures above 400°C.< / ftir> < / xrd> < / sem> < / mru>

Claims

1. Formula: Mo ａ V ｂ Te ｃ Ta ｄ O ｘ (In the formula, a is 1.0, b is between 0.35 and 0.

75. c is between 0.1 and 0.

2. d is between 0.06 and 0.

15. x is a number that satisfies at least the valence of the catalyst. It is represented as, A catalyst for the oxidative dehydrogenation of ethane, having an amorphous content of 30% to 50% by weight.

2. b is between 0.45 and 0.

7. c is between 0.14 and 0.

18. The catalyst according to claim 1, wherein d is 0.06 to 0.

1.

3. Formula: Mo １ V ０．４９ Te ０．１５ Ta ０．０７ The catalyst according to claim 1 or 2, as represented by the following:

4. The catalyst according to any one of claims 1 to 3, wherein the amorphous content of the catalyst is 30% to 40% by weight.

5. The catalyst according to any one of claims 1 to 4, wherein the amorphous content of the catalyst is 33% to 36% by weight.

6. The catalyst according to any one of claims 1 to 5, having a powder X-ray diffraction pattern including peaks at °2θ values ​​of 22.2±0.2, 26.7±0.2, and 28.3±0.

2.

7. The catalyst according to any one of claims 1 to 6, having a powder X-ray diffraction pattern including peaks at °2θ values ​​of 7.9±0.2, 9.0±0.2, 22.2±0.2, 23.0±0.2, 25.0±0.2, 26.7±0.2 and 28.3±0.

2.

8. A catalyst material comprising the catalyst according to any one of claims 1 to 7 and a catalyst support or carrier.

9. The catalyst material according to claim 8, wherein the catalyst support or carrier is selected from the group consisting of precipitated synthetic silica, fumed synthetic silica, silica-alumina, α-alumina, and anatase-type titania.

10. The catalyst material according to claim 8 or 9, wherein the catalyst support or carrier is precipitated synthetic silica.

11. A process for the oxidative dehydrogenation of ethane, the process comprising contacting a gaseous feed containing ethane and oxygen with a catalyst in a reactor to produce an effluent containing ethylene, the catalyst being Formula: Mo ａ V ｂ Te ｃ Ta ｄ O ｘ (In the formula, a is 1.0, b is between 0.35 and 0.

75. c is between 0.1 and 0.

2. d is between 0.06 and 0.

15. x is a number that satisfies at least the valence of the catalyst. It is represented as, The amorphous content of the catalyst is 30% to 50% by weight in the process.

12. Formula: Mo １ V ０．４９ Te ０．１５ Ta ０．０７ The process according to claim 11, represented as:

13. The process according to claim 11 or 12, wherein the amorphous content of the catalyst is 30% to 40% by weight.

14. The process according to any one of claims 11 to 13, wherein the catalyst has an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at a temperature of 350°C to 475°C.

15. The process according to any one of claims 11 to 14, wherein the catalyst has an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at a temperature of 400°C to 450°C.

16. The process according to claim 11 or 12, wherein the catalyst has an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at a temperature of 350°C to 475°C for 110 hours.

17. The process according to claim 16, wherein the catalyst has an ethane conversion rate of 50 mol% and an ethylene selectivity of 90% or more at a temperature of 400°C to 450°C for 110 hours.

Images