Method for preparing a catalyst for oxidative dehydrogenation

Abstract

A method for preparing a catalyst is provided. An exemplary method includes forming a slurry containing a metal oxide, a reducing agent, and water, and heating the slurry to form a catalyst. The metal oxide includes molybdenum oxide, vanadium oxide, tellurium oxide, or antimony oxide, or both, and tantalum oxide or niobium oxide, or both. The ratio of water in the slurry to the amount of catalyst formed is in the range between 0.1 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

Description

[Technical Field]

[0001] This disclosure generally relates to the preparation of catalysts and catalytic materials for the oxidative dehydrogenation (ODH) of alkanes such as ethane. More specifically, catalysts prepared by the methods disclosed herein include molybdenum (Mo), vanadium (V), tellurium (Te) or antimony (Sb) or both, tantalum (Ta) or niobium (Nb) or both, 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 hydrocarbons diluted with steam to temperatures of at least 600°C for a short period. The fuel demand to generate the required temperature and the need for equipment capable of withstanding that temperature significantly increases the overall cost. 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, nitrogen, or vapor), and reacted at a relatively low temperature of 300°C to produce the corresponding alkenes. 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 low selectivity, may be hindering its commercial adoption. Furthermore, the synthesis procedures for catalysts used in ODH require large amounts of water, potentially generating significant heavy metal-contaminated waste. Improved methods are needed to prepare catalysts with high selectivity, activity, and long lifetime in the ODH reaction. [Overview of the Initiative]

[0004] Provided herein is a method for preparing a catalyst. This method comprises the steps of forming a slurry containing a metal oxide, a reducing agent, and water, and heating the slurry to form a catalyst. The metal oxides include molybdenum oxide, vanadium oxide, tellurium oxide, or antimony oxide, or both, and tantalum oxide or niobium oxide, or both. The ratio of water in the slurry to the amount of catalyst formed is in the range of 0.1 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

[0005] In some embodiments, the ratio of water in the slurry to the amount of catalyst formed is in the range between 0.2 mL of water per gram of catalyst and 1 mL of water per gram of catalyst.

[0006] In some embodiments, the slurry has a water-to-metal oxide ratio ranging from 0.2 mL of water per gram of metal oxide to 0.6 mL of water per gram of metal oxide. In some embodiments, the slurry has a water-to-metal oxide ratio ranging from 0.3 mL of water per gram of metal oxide to 0.5 mL of water per gram of metal oxide.

[0007] In some embodiments, the molybdenum oxide is MoO3.

[0008] In some embodiments, the vanadium oxide is V2O5.

[0009] In some embodiments, the oxide present is TeO2 if tellurium oxide is present, and Sb2O5 if antimony oxide is present.

[0010] In some embodiments, if tantalum oxide is present, it is Ta2O5·xH2O, and if niobium oxide is present, it is Nb2O5·xH2O.

[0011] In some embodiments, the method further includes grinding, wet milling, dry milling, or crushing the metal oxide. In some embodiments, the method further includes grinding, wet milling, dry milling, or crushing the metal oxide and the reducing agent.

[0012] In some embodiments, the reducing agent comprises an alcohol, a carboxylic acid, or an ester. In some embodiments, the reducing agent is oxalic acid or ethanol. In some embodiments, the reducing agent is oxalic acid. In some embodiments, the slurry comprises one or less reducing agents.

[0013] In some embodiments, the method includes heating the slurry by raising the temperature from the ambient temperature to a temperature of 100°C to 200°C over a heating-up time of 2 hours to 48 hours, and holding the temperature at a holding temperature of 100°C to 200°C for a holding time of 12 hours to 120 hours.

[0014] In some embodiments, the method further includes washing the catalyst with water.

[0015] In some embodiments, the method further includes firing the catalyst to form a fired catalyst. In some embodiments, the method includes firing the catalyst by placing the catalyst in a furnace in an oxygen-free environment, raising the temperature of the furnace from the ambient temperature to a temperature of 500°C to 620°C over a heating-up time of 2 hours to 10 hours, and holding the temperature of the furnace at a holding temperature of 500°C to 620°C for a holding time of 1 hour to 10 hours.

[0016] In some embodiments, the ratio of water in the slurry to the amount of the formed fired catalyst is less than 1 mL of water per 1 gram of the fired catalyst.

[0017] In some embodiments, the catalyst is Mo a V b Te c Ta d O x , Mo a V b Sb c Ta d O x , Mo a V b Te c Nb d O x , and Mo a V b Sb c Nb d O xThe formula is selected from the following, where a is 1.0, b is 0.01 to 0.4, c is 0.01 to 0.2, d is 0.01 to 0.10, x is the number of oxygen atoms required to make the catalyst electrically neutral, and a, b, c, and d are determined based on the amount of each metal oxide added to the slurry. In some embodiments, the values ​​of a, b, c, and d are also determined by elemental analysis. In some embodiments, b is 0.2 to 0.4, c is 0.03 to 0.07, and d is 0.01 to 0.06.

[0018] In some embodiments, the catalyst is Mo1V 0.31 Te 0.05 Ta 0.05 O x Mo1V 0.31 S 0.05 Ta 0.05 O x Mo1V 0.31 Te 0.05 Nb 0.05 O x , and Mo1V 0.31 S 0.05 Nb 0.05 O x It has an expression that is selected from.

[0019] In some embodiments, the catalyst is Mo1V 0.32 Te 0.05 Ta 0.02 O x Mo1V 0.32 S 0.05 Ta 0.02 O x Mo1V 0.31 Te 0.04 Nb 0.02 O x Mo1V 0.30 S 0.05 Nb 0.02 O x Mo1V 0.34 Te 0.05 Ta 0.02 Mo1V 0.34 Te 0.06 Ta 0.02 Mo1V 0.34 S 0.06 Ta 0.02 Mo1V0.34 Te 0.05 Nb 0.01 Mo1V 0.32 S 0.06 Nb 0.02 Mo1V 0.34 Te 0.05 Ta 0.02 , and Mo1V 0.34 S 0.05 Ta 0.03 It has an equation selected from the following, each equation determined by energy-dispersive X-ray spectroscopy (EDX).

[0020] In some embodiments, the metal oxide has a particle size distribution in the range of 0.5 μm to 250 μm.

[0021] In some embodiments, the ratio of the total amount of water used to prepare the catalyst is in the range of 0.2 mL of water per gram of catalyst and 25 mL of water per gram of catalyst. In some embodiments, the ratio of the total amount of water used to prepare the catalyst is in the range of 0.2 mL of water per gram of catalyst and 10 mL of water per gram of catalyst. [Brief explanation of the drawing]

[0022] [Figure 1] This is the PXRD pattern for Example 2E. [Figure 2] This is the PXRD pattern for Example 3E. [Figure 3] This is the PXRD pattern for Example 4E. [Figure 4] Examples 5E to 7E are superimposed PXRD patterns. [Figure 5] Examples 8E to 10E are superimposed PXRD patterns. [Figure 6] This is the PXRD pattern for Example 12E. [Figure 7] This is the PXRD pattern for Example 12E (pellet-shaped). [Figure 8] The scanning electron microscope (SEM) image of Example 3E is shown. [Figure 9] The SEM image of Example 4E is shown. [Figure 10] The SEM image of Example 5E is shown. [Figure 11] The SEM image of Example 6E is shown. [Figure 12] The SEM image of Example 7E is shown. [Figure 13] The SEM image of Example 9E is shown. [Figure 14] The SEM image of Example 11E is shown. [Figure 15] This is a plot of the ethane conversion rates for calcined catalyst examples 3E and 8E-10E. [Figure 16] This is a plot of the combined selectivity of ethylene and acetic acid produced by calcined catalyst examples 3E and 8E-10E. [Figure 17] This is a plot of the ethane conversion rates for calcined catalyst examples 5E and 11E. [Figure 18] This is a plot of the combined selectivity of ethylene and acetic acid produced by calcined catalyst examples 5E and 11E. [Modes for carrying out the invention]

[0023] Hereinafter, specific embodiments of the disclosed subject matter will be described in detail, examples of which are partially shown in the accompanying drawings. The disclosed subject matter will be described in conjunction with the enumerated claims, but it will be understood that the illustrated subject matter is not intended to limit the claims.

[0024] Selective oxidation (SO) is commonly used in oxidative dehydrogenation (ODH) reactions to produce alpha-olefins from corresponding alkanes, such as ethylene from ethane. Provided in this disclosure is a method for synthesizing catalysts for use, for example, in ODH processes. In this method, catalyst precursor powders are mixed, for example by grinding, and then used in a hydrothermal synthesis process to form a catalyst. Conventional procedures have used large amounts of water in the hydrothermal synthesis process. However, the use of large amounts of water in synthesis can generate large amounts of heavy metal-contaminated waste.

[0025] The catalyst synthesis embodiments described herein offer simpler procedures, utilize less water, and significantly reduce the amount of heavy metal-contaminated waste generated during synthesis. For example, the method provided herein can reduce the water used for catalyst synthesis to about 1 / 30th and the water used for washing to about 1 / 4th compared to other procedures for forming catalysts using metal oxide precursors.

[0026] Furthermore, the method provided herein does not require the complex mixing or grinding steps reported in conventional synthesis procedures for the relevant MoVNbTe oxides. The method provided herein achieves significant cost reductions and simplification compared to previously reported synthesis procedures.

[0027] Provided herein is a method for preparing a catalyst, comprising forming a slurry containing a metal oxide, a reducing agent, and water, and heating the slurry to form a catalyst. Examples of metal oxides include molybdenum oxide, vanadium oxide, tellurium oxide, or antimony oxide, or both, and tantalum oxide, or niobium oxide, or both. In some embodiments, the molybdenum oxide is MoO3. In some embodiments, the vanadium oxide is V2O5. In some embodiments, the tellurium oxide is TeO2. In some embodiments, the antimony oxide is Sb2O5. In some embodiments, the tantalum oxide is Ta2O5·xH2O. In some embodiments, the niobium oxide is Nb2O5·xH2O.

[0028] As used herein, the term “catalyst” generally refers to the active catalytic portion of a catalytic material capable of promoting oxidative dehydrogenation, such as the oxidative dehydrogenation of ethane to ethylene. The catalyst may be further processed to form a catalytic material. The catalytic material may also be further processed to form a final catalytic material.

[0029] As used herein, the term “catalytic material” refers to a material comprising an active catalyst capable of promoting the oxidative dehydrogenation of ethane to ethylene. The catalytic material may include a carrier and / or support. The catalytic material may consist substantially of a catalyst. 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, 3D printed catalytic materials, spheroidized catalytic materials, compression-molded catalytic materials, and cast catalytic materials. Non-limiting examples of compression-molded and cast catalytic materials include pellets such as tablets, elliptical or spherical particles. A binder may be used to assist in the formation of the catalytic material. The formation of the catalytic material may include optional work-up steps such as debindering, calcination / sintering, and / or activation / pretreatment. Work-up steps may be introduced to prepare the catalytic material for loading into the reactor, to achieve the expected productivity, and to mitigate unexpected thermal runaway during startup.

[0030] A method for preparing a catalyst disclosed herein involves forming a slurry containing a metal oxide, a reducing agent, and water. As used herein, the term “slurry” refers to a mixture of solids in a liquid and includes suspensions, pastes (i.e., mixtures that are viscous enough that they cannot move freely), or colloidal solutions.

[0031] The ratio of water in the slurry to the amount of catalyst formed is in the range of 0.1 ml to 10 ml of water per gram of catalyst. As used herein, the term "water in slurry" refers to the amount of water used to form the slurry for the hydrothermal synthesis reaction and does not include water that is not consumed or contaminated during the reaction, or water used after the reaction. For example, "water in slurry" does not include water present in the hydrothermal synthesis vessel for heat transfer and / or maintenance of a humid atmosphere, or water used to wash the catalyst.

[0032] As used herein, “water” may refer to deionized water, distilled water, etc. In some embodiments, water is distilled water. In some embodiments, water is distilled deionized water. In some embodiments, the water may contain high levels of contaminants without harming the catalyst.

[0033] In some embodiments, the ratio of water in the slurry to the amount of catalyst formed is in the range of 0.1 ml to 5 ml of water per gram of catalyst, for example, between 0.1 ml to 4 ml of water per gram of catalyst, between 0.1 ml to 3 ml of water per gram of catalyst, between 0.1 ml to 2 ml of water per gram of catalyst, between 0.1 ml to 1 ml of water per gram of catalyst, or between 0.1 ml to 0.5 ml of water per gram of catalyst. In some embodiments, the ratio of water in the slurry to the amount of catalyst formed is in the range of 0.2 ml to 1 ml of water per gram of catalyst. In some embodiments, the ratio of water in the slurry to the amount of catalyst formed is in the range of 0.3 ml to 0.5 ml of water per gram of catalyst.

[0034] In some embodiments, the ratio of water in the slurry to the amount of catalyst formed is 0.1 ml of water per gram of catalyst, 0.2 ml of water per gram of catalyst, 0.3 ml of water per gram of catalyst, 0.4 ml of water per gram of catalyst, 0.5 ml of water per gram of catalyst, 0.6 ml of water per gram of catalyst, 0.7 ml of water per gram of catalyst, 0.8 ml of water per gram of catalyst, 0.9 ml of water per gram of catalyst, 1 ml of water per gram of catalyst, 2 ml of water per gram of catalyst, 3 ml of water per gram of catalyst, 4 ml of water per gram of catalyst, or 5 ml of water per gram of catalyst.

[0035] In some embodiments, the amount of water used in the slurry is minimized by optimizing the ratio of water in the slurry to the amount of catalyst formed, thereby minimizing the amount of wastewater generated while maintaining the saturated vapor pressure in the hydrothermal synthesis reaction.

[0036] In some embodiments, the slurry has a water-to-metal oxide ratio in the range of 0.1 mL of water per gram of metal oxide and 10 mL of water per gram of metal oxide, for example, between 0.1 mL of water per gram of metal oxide and 5 mL of water per gram of metal oxide, between 0.1 mL of water per gram of metal oxide and 4 mL of water per gram of metal oxide, between 0.1 mL of water per gram of metal oxide and 3 mL of water per gram of metal oxide, between 0.1 mL of water per gram of metal oxide and 2 mL of water per gram of metal oxide, or between 0.1 mL of water per gram of metal oxide and 1 mL of water per gram of metal oxide.

[0037] As used herein, the phrase "ratio of water to metal oxide" refers to the ratio of water used in the slurry to the total mass of metal oxide used in the slurry, and the metal oxides include molybdenum oxide, vanadium oxide, tellurium oxide, or antimony oxide, or both, and tantalum oxide or niobium oxide, or both. In embodiments where the reducing agent is a metal oxide, the total mass of metal oxide used in the slurry does not include the mass of the metal oxide used as the reducing agent.

[0038] In some embodiments, the slurry has a water-to-metal oxide ratio in the range of 0.2 mL of water per gram of metal oxide and 0.6 mL of water per gram of metal oxide, for example, between 0.3 mL of water per gram of metal oxide and 0.5 mL of water per gram of metal oxide, or between 0.3 mL of water per gram of metal oxide and 0.4 mL of water per gram of metal oxide, or between 0.4 mL of water per gram of metal oxide and 0.45 mL of water per gram of metal oxide. In some embodiments, the slurry has a water-to-metal oxide ratio in the range of 0.40 mL of water per gram of metal oxide and 0.43 mL of water per gram of metal oxide.

[0039] In some embodiments, the slurry has a water-to-metal oxide ratio of 0.1 mL per gram of metal oxide, 0.2 mL per gram of metal oxide, 0.3 mL per gram of metal oxide, 0.4 mL per gram of metal oxide, 0.5 mL per gram of metal oxide, 0.6 mL per gram of metal oxide, 0.7 mL per gram of metal oxide, 0.8 mL per gram of metal oxide, 0.9 mL per gram of metal oxide, 1 mL per gram of metal oxide, 2 mL per gram of metal oxide, 3 mL per gram of metal oxide, 4 mL per gram of metal oxide, or 5 mL per gram of metal oxide.

[0040] In some embodiments, the slurry has a water-to-metal oxide ratio of 0.30 mL per gram of metal oxide, 0.31 mL per gram of metal oxide, 0.32 mL per gram of metal oxide, 0.33 mL per gram of metal oxide, 0.34 mL per gram of metal oxide, 0.35 mL per gram of metal oxide, 0.36 mL per gram of metal oxide, 0.37 mL per gram of metal oxide, 0.38 mL per gram of metal oxide, 0.39 mL per gram of metal oxide, 0.40 mL per gram of metal oxide, 0.41 mL per gram of metal oxide, 0.42 mL per gram of metal oxide, 0.43 mL per gram of metal oxide, 0.44 mL per gram of metal oxide, or 0.45 mL per gram of metal oxide.

[0041] The amount of reducing agent used in the slurry may be selected based in part on the properties of the reducing agent used. In some embodiments, the slurry has a ratio of reducing agent used in the slurry to the amount of metal oxide used in the slurry, ranging from 0.01 g to 1.0 g of reducing agent per gram of metal oxide. As used herein, the term "reducing agent" in the expression "ratio of reducing agent used in the slurry to the amount of metal oxide used in the slurry" refers to the total mass of reducing agent used in the slurry, which may be the mass of one type of reducing agent, the mass of one or fewer types of reducing agents, or the combined mass of two or more types of reducing agents. As used herein, the term "metal oxide used in the slurry" in the expression "ratio of reducing agent used in the slurry to the amount of metal oxide used in the slurry" refers to the total mass of metal oxide used in the slurry, which may include molybdenum oxide, vanadium oxide, tellurium oxide or antimony oxide or both, and tantalum oxide or niobium oxide or both. In embodiments where the reducing agent is a metal oxide, the total mass of metal oxides used in the slurry does not include the mass of the metal oxide used as the reducing agent.

[0042] In some embodiments, the ratio of reducing agent used in the slurry to the metal oxide used in the slurry is in the range of 0.1 g and 0.5 g of reducing agent per gram of metal oxide. In some embodiments, the ratio of reducing agent used in the slurry to the metal oxide used in the slurry is in the range of 0.15 g and 0.25 g of reducing agent per gram of metal oxide. In a non-limiting example, the reducing agent is oxalic acid, the amount of oxalic acid used in the slurry is in the range of 0.15 g and 0.25 g, and the amount of metal oxide used in the slurry is in the range of 6 g and 8 g. In another non-limiting example, the amount of oxalic acid used in the slurry is in the range of 3.5 g and 7 g, and the amount of metal oxide used in the slurry is in the range of 20 g and 35 g.

[0043] Any suitable reducing agent may be included in the slurry. As used herein, the term “reducing agent” refers to a chemical substance that can reduce the oxidation state of one or more metals among the metal oxides in the slurry. Suitable reducing agents for promoting the reaction include those that are easily decomposed or oxidized during the reaction process.

[0044] In some embodiments, the reducing agent is an alcohol, a carboxylic acid, an ester, or a metal oxide. Suitable examples of alcohol reducing agents include, but are not limited to, ethanol, methanol, reducing sugars, and polyols such as glycols and glycerol. Suitable examples of carboxylic acid reducing agents include, but are not limited to, oxalic acid, formic acid, acetic acid, and citric acid. Suitable examples of ester reducing agents include, but are not limited to, ethyl acetate, dimethyl carbonate, dimethyl oxalate, and diethyl oxalate. A suitable metal oxide is vanadium(IV) oxide. In some embodiments, the reducing agent is oxalic acid or ethanol. In some embodiments, the reducing agent is oxalic acid. In some embodiments, the reducing agent is ethanol.

[0045] The slurry may contain one reducing agent or two or more reducing agents. In some embodiments, the slurry contains one or more reducing agents. In some embodiments, the slurry contains one or fewer reducing agents. The methods disclosed herein offer the advantage of a simplified procedure using a single reducing agent compared to previously reported methods using two or more reducing agents.

[0046] The methods disclosed herein may further include processes for controlling the size of a metal oxide. For example, the metal oxide may be pulverized, wet-pulverized, dry-pulverized, or crushed. A controlled size-reducing process can reduce the size of the metal oxide to improve its reactivity, or enable the aggregation of the metal oxide to enable the production of low-dusting powders or granules, and improve the loadability of the powder into the apparatus (e.g., improve the flowability or granulation of the powder).

[0047] In some embodiments, the metal oxide has a particle size of less than 1 mm, for example, less than 60 mesh (less than 250 μm). For example, the metal oxide may have a particle size in the range of 0.5 μm to 250 μm, or 1 μm to 200 μm, or 1 μm to 150 μm, or 1 μm to 100 μm, or 1 μm to 50 μm, or 10 μm to 200 μm, or 10 μm to 150 μm, or 10 μm to 100 μm, or 10 μm to 50 μm, or 50 μm to 200 μm, or 50 μm to 150 μm, or 50 μm to 100 μm.

[0048] In some embodiments, the method further includes a process for controlling the size of the metal oxide and the reducing agent. For example, the metal oxide and the reducing agent are pulverized, wet-pulverized, dry-pulverized, or crushed.

[0049] In some embodiments, the slurry is substantially free of strong acids. Those skilled in the art will understand that strong acids are acids that are completely or nearly completely ionized in solution. For example, in some embodiments, the slurry is substantially free of nitric acid.

[0050] In some embodiments, the slurry contains a tellurium compound. In some embodiments, the slurry is substantially free of a tellurium compound. As used herein, the term “substantially free” means less than 10 ppm, less than 5 ppm, less than 2 ppm, or less than 1 ppm.

[0051] In the methods disclosed herein, the catalyst is produced in a hydrothermal synthesis reaction by heating a slurry. Any suitable reaction vessel can be used for the hydrothermal synthesis reaction. In some embodiments, the slurry is heated in a hydrothermal synthesis vessel. In some embodiments, the slurry is formed in a hydrothermal synthesis vessel and then heated in the hydrothermal synthesis vessel. In some embodiments, the slurry is transferred to a hydrothermal synthesis vessel after slurry formation and then heated in the hydrothermal synthesis vessel.

[0052] As used herein, the term “hydrothermal synthesis vessel” refers to a reaction vessel suitable for carrying out a reaction under high temperature and pressure, and includes, but is not limited to, autoclaves, decomposition tanks, pressure vessels, hydrothermal synthesis reactors, or polytetrafluoroethylene (PFTE) high-pressure tanks. In some embodiments, the hydrothermal synthesis vessel is an autoclave.

[0053] A slurry can be heated by increasing its temperature and then maintaining that temperature. Temperature increases can be used to avoid surface boiling of the slurry. As used herein, the expression "temperature increase" refers to changing the temperature from an initial temperature to a final temperature over a period of time. For example, the temperature of a slurry can be increased from an initial temperature of room temperature to a final temperature higher than room temperature over a specified period of time. The final temperature may also be the holding temperature. As used herein, the term "room temperature" refers to a temperature between 15°C and 28°C. As used herein, the term "holding temperature" refers to the temperature at which the reaction vessel is held, which can be measured by the ambient temperature of the oven in which the reaction vessel is placed.

[0054] In some embodiments, the slurry is heated by raising its temperature from ambient temperature to a temperature between 100°C and 200°C over a heating time of 2 hours and 48 hours, and then holding it at a holding temperature between 100°C and 200°C for a holding time of 12 hours and 120 hours. In some embodiments, the slurry is heated by raising its temperature from ambient temperature to a temperature between 150°C and 200°C over a heating time of 2 hours and 24 hours, and then holding it at a holding temperature between 150°C and 200°C for a holding time of 24 hours and 60 hours.

[0055] In a non-limiting example, the slurry is heated by raising its temperature from ambient temperature to 180°C over 12 hours, and then holding it at 180°C for 48 hours. In another non-limiting example, the slurry is heated by raising its temperature from ambient temperature to 180°C over 24 hours, and then holding it at 180°C for 60 hours. In yet another non-limiting example, the slurry is heated by raising its temperature from ambient temperature to 180°C over 2 hours, and then holding it at 180°C for 48 hours.

[0056] In some embodiments, the method further includes a step of washing the catalyst with water. For example, the catalyst may be washed with water until the filtrate is colorless. In some embodiments, the method further includes a step of drying the catalyst at a temperature below 100°C, for example. Drying can be carried out by any suitable method, such as drying at room temperature for a suitable amount of time, or drying overnight in an oven at a temperature of 90°C, for example.

[0057] The method may further include the step of calcining the catalyst to form a calcined catalyst. Those skilled in the art will be familiar with appropriate methods for calcining catalysts. In some embodiments, the catalyst is calcined by placing it in a furnace in an oxygen-free environment, raising the furnace temperature from ambient temperature to 500°C to 620°C over a heating time of 2 to 10 hours, and maintaining the furnace temperature at a holding temperature of 500°C to 620°C for a holding time of 1 to 10 hours. For example, the catalyst can be calcined by placing it in a furnace, raising the furnace temperature from ambient temperature to 600°C over a heating time of 6 hours, and maintaining the furnace temperature at a holding temperature of 600°C for a holding time of 2 hours.

[0058] As used herein, “oxygen-free environment” refers to an environment with a molecular oxygen content of less than 10 ppm. For example, the furnace may be placed in an inert atmosphere such as a purified nitrogen atmosphere or a purified argon atmosphere, or in a CO2 atmosphere and / or a vapor atmosphere.

[0059] In some embodiments, the ratio of water in the slurry to the amount of calcined catalyst is in the range between 0.1 mL of water per gram of calcined catalyst and 10 mL of water per gram of calcined catalyst, for example, between 0.1 mL of water per gram of calcined catalyst and 5 mL of water per gram of calcined catalyst, between 0.1 mL of water per gram of calcined catalyst and 4 mL of water per gram of calcined catalyst, between 0.1 mL of water per gram of calcined catalyst and 3 mL of water per gram of calcined catalyst, between 0.1 mL of water per gram of calcined catalyst and 2 mL of water per gram of calcined catalyst, or between 0.1 mL of water per gram of calcined catalyst and 1 mL of water per gram of calcined catalyst. As used herein, the term "amount of calcined catalyst" refers to the mass of catalyst after all catalysts obtained from catalyst synthesis have undergone calcination, such as calcination, as described herein. In non-limiting examples, the ratio of water in the slurry to the amount of calcined catalyst may be in the range between 0.3 mL of water per gram of calcined catalyst and 0.8 mL of water per gram of calcined catalyst, in the range between 0.4 mL of water per gram of calcined catalyst and 0.6 mL of water per gram of calcined catalyst, or 0.5 mL of water per gram of calcined catalyst.

[0060] In some embodiments, the ratio of water in the slurry to the amount of calcined catalyst is 0.1 mL of water per gram of calcined catalyst, 0.2 mL of water per gram of calcined catalyst, 0.3 mL of water per gram of calcined catalyst, 0.4 mL of water per gram of calcined catalyst, 0.5 mL of water per gram of calcined catalyst, 0.6 mL of water per gram of calcined catalyst, 0.7 mL of water per gram of calcined catalyst, 0.8 mL of water per gram of calcined catalyst, 0.9 mL of water per gram of calcined catalyst, 1 mL of water per gram of calcined catalyst, 2 mL of water per gram of calcined catalyst, 3 mL of water per gram of calcined catalyst, 4 mL of water per gram of calcined catalyst, or 5 mL of water per gram of calcined catalyst.

[0061] In some embodiments, the ratio of water in the slurry to the amount of calcined catalyst formed is 0.45 mL of water per gram of calcined catalyst, 0.46 mL of water per gram of calcined catalyst, 0.47 mL of water per gram of calcined catalyst, 0.48 mL of water per gram of calcined catalyst, 0.49 mL of water per gram of calcined catalyst, 0.50 mL of water per gram of calcined catalyst, 0.51 mL of water per gram of calcined catalyst, 0.52 mL of water per gram of calcined catalyst, 0.53 mL of water per gram of calcined catalyst, 0 The amounts are 0.54 mL, 0.55 mL of water per gram of calcined catalyst, 0.56 mL of water per gram of calcined catalyst, or 0.57 mL of water per gram of calcined catalyst, 0.58 mL of water per gram of calcined catalyst, 0.59 mL of water per gram of calcined catalyst, 0.60 mL of water per gram of calcined catalyst, 0.61 mL of water per gram of calcined catalyst, 0.62 mL of water per gram of calcined catalyst, or 0.63 mL of water per gram of calcined catalyst, 0.64 mL of water per gram of calcined catalyst, or 0.65 mL of water per gram of calcined catalyst.

[0062] In some embodiments, the ratio of the total amount of water used to prepare the catalyst is between 0.1 mL of water per gram of catalyst and 60 mL of water per gram of catalyst. In some embodiments, the ratio of the total amount of water used to prepare the catalyst is between 0.1 mL of water per gram of catalyst and 25 mL of water per gram of catalyst. As used herein, “total amount of water used to prepare the catalyst” includes not only water in the slurry but also water used in other steps, such as any step of washing the catalyst with water, and / or water used to transfer materials between reaction vessels.

[0063] In some embodiments, the ratio of the total amount of water used to prepare the catalyst is in the range of 0.1 mL of water per gram of catalyst and 20 mL of water per gram of catalyst, 0.5 mL of water per gram of catalyst and 15 mL of water per gram of catalyst, 1 mL of water per gram of catalyst and 10 mL of water per gram of catalyst, 5 mL of water per gram of catalyst and 10 mL of water per gram of catalyst, 0.1 mL of water per gram of catalyst and 5 mL of water per gram of catalyst, or 0.1 mL of water per gram of catalyst and 1 mL of water per gram of catalyst. In some embodiments, the ratio of the total amount of water used to prepare the catalyst is in the range of 0.2 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

[0064] In some embodiments, the methods disclosed herein may further include providing a catalytic material by combining a calcined catalyst with one or more of a solid support, a carrier, a binder, and a lubricant. In some embodiments, the catalytic material is prepared from an aqueous mixture comprising (i) a catalyst disclosed herein, (ii) a solid support or carrier, and (iii) a lubricant and / or a binder. In some embodiments, the catalytic support or carrier is at least one of precipitated synthetic silica, fumed synthetic silica, silica-alumina, α-alumina, and anatase-type titania. In some embodiments, the catalytic support or carrier is precipitated synthetic silica. In some embodiments, the catalytic support or carrier is α-alumina. In some embodiments, a binder is used to assist in the formation of the catalytic material.

[0065] In some embodiments, the formation of the catalyst material includes any work-up steps such as debinding, firing / sintering, and / or activation / pre-treatment. The work-up steps can be introduced to prepare the catalyst material to be loaded into the reactor, achieve the expected productivity, and reduce unexpected thermal runaway during startup. In some embodiments, the step of preparing the catalyst material can further include removing a substantial amount of water (e.g., 50 wt% - 99 wt%) from the aqueous mixture, for example, by heating the mixture at a temperature of 50°C to 100°C. In some embodiments, the method includes forming the catalyst material into a formed catalyst material, such as a pelletized catalyst material.

[0066] The catalyst prepared by the method disclosed herein contains molybdenum (Mo), vanadium (V), tellurium (Te) or antimony (Sb) or both, tantalum (Ta) or niobium (Nb) or both, and oxygen (O). In some embodiments, the catalyst is Mo a V b Te c Ta d O x 、Mo a V b Sb c Ta d O x 、Mo a V b Te c Nb d O x 、and Mo a V b Sb c Nb d O x and has a formula selected from. The values of a, b, c, and d may refer to values based on the amount (molar equivalent) of each metal oxide added to the slurry, or may refer to values measured by elemental analysis such as inductively coupled plasma mass spectrometry (ICP-MS), neutron activation analysis (NAA), X-ray fluorescence analysis (XRF), ion chromatography mass spectrometry (IC-MS), proton-induced X-ray analysis (PIXE), energy-dispersive X-ray spectroscopy (EDX), etc.

[0067] The catalytic chemical formula can be selected in relation to the ratios of values ​​a, b, c, and d to affect the catalytic activity, selectivity, purity, and stability. In some embodiments, the value of d is minimized to reduce costs while maintaining good catalytic performance.

[0068] In some embodiments, a is 1.0.

[0069] In some embodiments, b is 0.01 to 0.4. In some embodiments, b is 0.2 to 0.4. In some embodiments, b is 0.01 to 0.3. In some embodiments, b is 0.1 to 0.3. In some embodiments, b is 0.30 to 0.35. In some embodiments, b is 0.30 to 0.32. In some embodiments, b is 0.31.

[0070] In some embodiments, c is 0.01 to 0.2. In some embodiments, c is 0.01 to 0.1. In some embodiments, c is 0.01 to 0.09. In some embodiments, c is 0.01 to 0.07. In some embodiments, c is 0.03 to 0.07. In some embodiments, c is 0.04 to 0.05. In some embodiments, c is 0.05.

[0071] In some embodiments, d is 0.01 to 0.10. In some embodiments, d is 0.01 to 0.06. In some embodiments, d is 0.01 to 0.05. In some embodiments, d is 0.02 to 0.05. In some embodiments, d is 0.03 to 0.05. In some embodiments, d is 0.05.

[0072] Each catalyst formulation according to this disclosure contains an amount of oxygen sufficient to electrically neutralize the catalyst. Those skilled in the art will understand that oxygen-containing species can also be adsorbed or captured by the catalyst.

[0073] In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo a V b Te c Ta d O x where the values of a, b, c, and d are as described herein. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo a V b Sb c Ta d O x where the values of a, b, c, and d are as described herein. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo a V b Te c Nb d O x where the values of a, b, c, and d are as described herein. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo a V b Sb c Nb d O x where the values of a, b, c, and d are as described herein.

[0074] In some embodiments, the values of a, b, c, and d are determined by elemental analysis such as EDX. In some embodiments, b is 0.31 - 0.34, c is 0.05 - 0.06, d is 0.01 - 0.03, and the values of a, b, c, and d are determined by EDX. In some embodiments, the catalyst prepared by the method disclosed herein is Mo1V 0.32 Te 0.05 Ta 0.02 O x , Mo(1)V 0.32 Sb 0.05 Ta 0.02 O x , Mo(1)V 0.31 Te 0.04 Nb 0.02 O x , Mo(1)V 0.30 Sb 0.05Nb 0.02 O x Mo1V 0.34 Te 0.05 Ta 0.02 Mo1V 0.34 Te 0.06 Ta 0.02 Mo1V 0.34 S 0.06 Ta 0.02 Mo1V 0.34 Te 0.05 Nb 0.01 Mo1V 0.32 S 0.06 Nb 0.02 Mo1V 0.34 Te 0.05 Ta 0.02 , and Mo1V 0.34 S 0.05 Ta 0.03 It has an equation selected from the following, each equation determined by energy-dispersive X-ray spectroscopy (EDX).

[0075] In some embodiments, the catalyst prepared by the method disclosed herein is Mo1V 0.34 Te 0.05 Ta 0.02 Mo1V 0.34 Te 0.06 Ta 0.02 Mo1V 0.34 S 0.06 Ta 0.02 Mo1V 0.34 Te 0.05 Nb 0.01 Mo1V 0.32 S 0.06 Nb 0.02 , and Mo1V 0.34 S 0.05 Ta 0.03 It has an expression selected from, and each expression is determined by EDX.

[0076] In some embodiments, the catalyst prepared by the method disclosed herein is of formula Mo1V 0.32 Ta 0.02 Te 0.05 The formula is determined by EDX. In some embodiments, the catalyst prepared by the method disclosed herein is of the formula Mo1V 0.32Ta 0.02 S 0.05 The formula is determined by EDX. In some embodiments, the catalyst prepared by the method disclosed herein is of the formula Mo1V 0.31 Ni 0.02 Te 0.04 The formula is determined by EDX. In some embodiments, the catalyst prepared by the method disclosed herein is of the formula Mo1V 0.30 Ni 0.02 S 0.05 This formula has a value that is determined by EDX.

[0077] In some embodiments, the values ​​of a, b, c, and d are determined based on the amount of each metal oxide added to the slurry. In some embodiments, the catalyst prepared by the method disclosed herein is Mo1V 0.31 Te 0.5 Ta 0.5 O x Mo1V 0.31 S 0.5 Ta 0.5 O x Mo1V 0.31 Te 0.5 Nb 0.5 O x , and Mo1V 0.31 S 0.5 Nb 0.5 O x The catalyst has a formula selected from, each formula determined based on the amount of each metal oxide added to the slurry. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo1V 0.31 Te 0.05 Ta 0.05 O x The formula is determined based on the amount of each metal oxide added to the slurry. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo1V 0.31 Ta 0.05 S 0.05 O x The formula is determined based on the amount of each metal oxide added to the slurry. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo1V0.31 Nb 0.05 Te 0.05 O x The formula is determined based on the amount of each metal oxide added to the slurry. In some embodiments, the catalyst prepared by the method disclosed herein has the formula Mo1V 0.31 Nb 0.05 S 0.05 O x The formula has the following characteristics, and this formula is determined based on the amount of each metal oxide added to the slurry.

[0078] In some embodiments of the methods disclosed herein, metal oxides include molybdenum oxide, vanadium oxide, tellurium oxide, and tantalum oxide. In some embodiments, metal oxides include MoO3, V2O5, TeO2, and Ta2O5·xH2O. In some embodiments, the slurry contains MoO3, V2O5, TeO2, and Ta2O5·xH2O in a mass ratio of MoO3:V2O5:TeO2:Ta2O5·xH2O, where the mass ratio is 1 g of MoO3, 0.1 to 0.3 g of V2O5, 0.01 g to 0.10 g of TeO2, and 0.01 g to 0.10 g of Ta2O5·xH2O. This mass ratio can be used on any suitable reaction scale. For example, the slurry may contain 4-6 g of MoO3, 0.5-1.5 g of V2O5, 0.1 g-0.5 g of TeO2, and 0.2 g-0.6 g of Ta2O5·xH2O.

[0079] In some embodiments, the metal oxides include molybdenum oxide, vanadium oxide, antimony oxide, and tantalum oxide. In some embodiments, the metal oxides include MoO3, V2O5, Sb2O5, and Ta2O5·xH2O. In some embodiments, the slurry contains MoO3, V2O5, Sb2O5, and Ta2O5·xH2O in a mass ratio of MoO3:V2O5:Sb2O5:Ta2O5·xH2O, where the mass ratio is 1g MoO3:0.1-0.3g V2O5:0.01g-0.10g Sb2O5:0.01g-0.10g Ta2O5·xH2O. This mass ratio can be used on any suitable reaction scale. For example, the slurry may contain 4-6 g of MoO3, 0.5-1.5 g of V2O5, 0.1-0.5 g of Sb2O5, and 0.2-0.6 g of Ta2O5·xH2O. In another non-limiting example, the slurry may contain 15-17 g of MoO3, 2-4 g of V2O5, 0.5-1.5 g of Sb2O5, and 1-3 g of Ta2O5·xH2O.

[0080] In some embodiments, the metal oxides include molybdenum oxide, vanadium oxide, tellurium oxide, and niobium oxide. In some embodiments, the metal oxides include MoO3, V2O5, TeO2, and Nb2O5·xH2O. In some embodiments, the slurry contains MoO3, V2O5, TeO2, and Nb2O5·xH2O in a mass ratio of MoO3:V2O5:TeO2:Nb2O5·xH2O, where the mass ratio is 1g MoO3:0.1-0.3g V2O5:0.01g-0.10g TeO2:0.01g-0.10g Nb2O5·xH2O. This mass ratio can be used on any suitable reaction scale. For example, the slurry may contain 4-6 g of MoO3, 0.5-1.5 g of V2O5, 0.1-0.5 g of TeO2, and 0.1-0.4 g of Nb2O5·xH2O. In another non-limiting example, the slurry may contain 26-28 g of MoO3, 4-6 g of V2O5, 1-3 g of TeO2, and 1-3 g of Nb2O5·xH2O.

[0081] In some embodiments, the metal oxides include molybdenum oxide, vanadium oxide, antimony oxide, and niobium oxide. In some embodiments, the metal oxides include MoO3, V2O5, Sb2O5, and Nb2O5·xH2O. In some embodiments, the slurry contains MoO3, V2O5, Sb2O5, and Nb2O5·xH2O in a mass ratio of MoO3:V2O5:Sb2O5:Nb2O5·xH2O, where the mass ratio is 1g MoO3:0.1-0.3g V2O5:0.01g-0.10g Sb2O5:0.01g-0.10g Nb2O5·xH2O. This mass ratio can be used on any suitable reaction scale. For example, the slurry may contain 4-6 g of MoO3, 0.5-1.5 g of V2O5, 0.1 g-0.5 g of Sb2O5, and 0.1 g-0.4 g of Nb2O5·xH2O.

[0082] Catalysts prepared by the methods disclosed herein may be suitable as catalysts in oxidative dehydrogenation reactions. Where used herein, the terms “oxidative dehydrogenation” or “ODH” refer to alkane (C) reactions, as further described herein. n H 2n+2 This refers to a process that combines the endothermic dehydrogenation of ) with the strong exothermic oxidation of hydrogen, thereby producing alpha-olefins, among other things. In some embodiments, the alkane refers to one or more of ethane, propane, butane, pentane, hexane, octane, decane, and dodecane. In certain embodiments, the alkane refers to ethane and propane, and in some embodiments, to ethane. When testing catalysts, the ODH reaction as used herein is assumed to refer to the ODH of ethane.

[0083] The conversion rate of ethane feed gas to the product in the ODH process is calculated as the change in the volume flow rate of ethane in the product compared to the volume flow rate of the feed ethane, using the following formula:

number

[0084] In Equation 1, C is the percentage (mol %) of the ethane feed gas converted from ethane to another product (i.e., the ethane conversion rate), and X is the molar concentration of the corresponding compound in the gaseous effluent discharged from the reactor at the corresponding temperature.

[0085] Furthermore, by analyzing the gas emitted from the reactor using gas chromatography, the selectivity of the catalyst or catalytic material to ethylene (i.e., the molar proportion of ethane that produces ethylene) can be determined. The selectivity to ethylene can be determined using the following formula:

number

[0086] In formula 2, S エチレン X is the selectivity to ethylene, and X is the molar concentration of the corresponding compound in the gaseous effluent discharged from the reactor at the corresponding temperature. As used herein, the term "selectivity to ethylene" refers to the molar proportion of the conversion or reacted ethane that produces ethylene.

[0087] The gas-per-spatiotemporal velocity (GHSV) is defined as the volumetric flow rate of the reactor feed gas divided by the volume of the catalyst bed. As used herein, the term “volume of the catalyst bed” refers to the volume occupied by catalyst particles, any diluent particles, and voids within the catalyst bed. For GHSV values ​​of catalyst materials, the catalyst bed is treated as catalyst only (without support), and it is assumed that the volume of the catalyst is the total volume of the measured catalyst material multiplied by the weight percentage of the catalyst. GHSV can be calculated based on the measured volume of compressed particles (before mixing with quartz sand, as described later) and varies depending on the bulk density of each catalyst or catalyst material. For the catalyst materials discussed herein, the reported GHSV is for catalyst only, and it is assumed that the volume of the catalyst is the total volume of the measured catalyst material multiplied by the weight percentage of the catalyst.

[0088] Although the numerical ranges and parameters representing the broad scope of this disclosure are approximations, the numerical values ​​shown in specific examples are reported as accurately as possible. However, each numerical value inherently contains a certain degree of error that inevitably arises from the standard deviation found in each test measurement.

[0089] Furthermore, it should be understood that any numerical range described herein is 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 of 1 and the stated maximum value of 10, i.e., the minimum value is 1 or greater and the maximum value is 10 or less. Since the disclosed numerical ranges are continuous, all values ​​between the minimum and maximum values ​​are included. Unless otherwise specified, the various numerical ranges specified in this application are approximations.

[0090] In this document, the terms "a," "an," or "the" are used to include one or more unless the context clearly indicates otherwise. The term "or" is used to refer to a non-exclusive "or" unless otherwise specified. The phrase "at least one of A and B" is synonymous with "A, B, or A and B." Please understand that expressions and terms used herein are for illustrative purposes only and not for limitation unless otherwise defined. [Examples]

[0091] <Preparation of comparative sample 1C>

[0092] <Synthesis of ammonium molybdate tellurate hydrate> First, ammonium molybdate tellurate hydrate ((NH4)6Mo6TeO 24 Ammonium molybdate hydrate ((NH4)6Mo7O) was prepared. 24530 g of 4H2O was added to 2400 mL of 80°C distilled water with stirring to obtain a pH 5.22 solution. Separately, 115 g of telluric acid (Te(OH)6; 115 g) was dissolved in 800 mL of 60°C distilled water. Then, using a dropping funnel, this telluric acid solution was added dropwise to the molybdate solution at 63°C over 10 minutes to prepare a pH 2.4 solution. Next, ammonium hydroxide (28 wt% aqueous solution) was added little by little (235 mL was used) until the pH of the solution reached 7.5. The solution was stirred in the air at that temperature and left to stand until the water evaporated to obtain a colorless solid, which was then dried overnight in a 90°C oven. Finally, 517 g of crystalline solid was obtained.

[0093] <Synthesis of comparative sample 1C> To prepare comparative sample 1C, ammonium tellurate molybdate hydrate (59.1633 g) was dissolved in 750 mL of distilled water preheated to 60°C with stirring. Separately, vanadyl sulfate hydrate (VOSO4·3.46H2O; 39.4405 g) was dissolved in 240 mL of distilled water preheated to 60°C with stirring. Next, the vanadyl sulfate solution was added dropwise to the molybdate solution over 12 minutes with stirring at 60°C to produce a black solution. To the black molybdate solution at 60°C, tantalum oxalate solution (0.400 mol / L Ta) preheated to 60°C was added. 5+ 117.6 mL was added dropwise over 11 minutes, and after stirring at 60°C for 1 hour, an olive-green slurry was produced. The resulting solution was turbid and contained fine precipitate. Next, this mixture was added to a glass-lined steel autoclave at 60°C, sealed, purged 10 times with nitrogen, and then left to stand under a nitrogen atmosphere of 20 psi. The autoclave was then heated at 166°C for 48 hours. After cooling to room temperature, the reactor was evacuated, the solution was vacuum filtered, and washed with distilled water to obtain a purplish-black solid. The solid was then dried overnight in an oven at 90°C to obtain 60.30 g of dry powder solid. Next, a portion of this solid was calcined in a furnace under a nitrogen stream over 6 hours to 600°C, held at 600°C for 2 hours, then the furnace was turned off, and the sample was cooled to room temperature over approximately 6 hours. A mass loss of 9.3% was observed during calcination.

[0094] The total amount of water used in the synthesis (excluding the washing solvent) was 1500.7 mL, yielding 54.45 g of calcined catalyst. This corresponds to 27.6 mL of water per gram of catalyst. This includes the water required for the preparation of the initial ammonium molybdate tellurate hydrate sample.

[0095] <Preparation of Examples 2E to 4E>

[0096] <Reagents> Molybdenum(VI) oxide (MoO3), vanadium(V) oxide (V2O5), tellurium dioxide (TeO2), oxalic acid dihydrate, polyethylene glycol 1000, MOWIOL® 8-88, and polyacrylic acid were purchased from Sigma Aldrich. Tantalum pentoxide hydrate (Ta2O5·xH2O) was purchased from BassTech International. The x value of Ta2O5·xH2O was measured as 2.57 by thermogravimetric analysis. Niobium pentoxide hydrate (Nb2O5·xH2O) was purchased from Companhia Brasileira de Metalurgia e Mineracao. The x value of Nb2O5·xH2O was measured as 4.57 by thermogravimetric analysis. Alpha alumina was purchased from Fisher Scientific Canada. All reagents were used without further purification. Distilled deionized water was used.

[0097] <Preparation of catalyst> Three separate examples (Examples 2E, 3E, and 4E) were prepared using the solid reagents listed in Table 1. For each example, the solid reagents were mixed and lightly ground using a mortar and pestle. This was primarily to break down the large crystals of oxalic acid dihydrate to better disperse them with the other solids. Next, the solid mixtures were transferred to separate 8 mL glass vials and 2 mL of distilled water solvent was added. The samples were lightly stirred with a glass stirring rod to form a thick orange slurry, and any sample adhering to the stirring rod was washed off with 1 mL of water before returning the mixture to the vials.

[0098] [Table 1]

[0099] Next, these vials were placed in a glass-lined steel autoclave along with a blank reference vial filled with water, and the water was filled to a solid height around the vials to promote heat transfer and maintain a humid atmosphere inside the vessel. The autoclave was a 300 mL PARR reactor manufactured by Parr Instrument Company in Maureen, Illinois, USA (assembly head serial number: 453HC T316 091902 24820B, assembly body serial number: 452HC T316 091902 24820A).

[0100] The autoclave was sealed and heated in an oven from room temperature to 180°C over 12 hours, then maintained at 180°C for 48 hours. After that, the power was turned off and it was cooled to room temperature over 3-4 hours. After the reaction, the sample became a hard, dark purple solid, and its volume had increased by approximately 1.5 times. The sample was scraped from the vial onto filter paper in a vacuum filtration apparatus and washed with approximately 50 mL of distilled water. The filtrate was a clear, pale blue for sample 2E, and a dark blue for samples 3E and 4E. The sample was washed until the filtrate was colorless and dried on the filter paper to obtain a glossy, dark purple powder solid.

[0101] Next, these solids were calcined in a tubular autoclave under an N2 gas flow (linear velocity of 3.9 cm / min at standard temperature and pressure (STP), residual oxygen 0.25 ppm (volume)) at 60°C for 12 hours. Afterward, the temperature was increased to 600°C over 6 hours, held at 600°C for 2 hours, then the furnace power was turned off, and the samples were cooled to room temperature over approximately 12 hours. After calcination, all samples were a dark purplish-black powder. The masses of the solid samples before and after calcination are shown in Table 2.

[0102] [Table 2]

[0103] In Example 3E, excluding the washing solvent, the total amount of water used in the synthesis was 3 mL, yielding 5.9457 g of calcined catalyst. This corresponds to 0.505 mL of water per gram of calcined catalyst, indicating a 54.6-fold reduction in the amount of solvent required compared to comparative sample 1C.

[0104] <Preparation of Examples 5E to 7E> Three separate examples (Examples 5E, 6E, and 7E) were prepared using the reagents listed in Table 3. In Example 5E, the procedure in Example 4E was repeated, with the TeO2 in the reaction replaced by a molar equivalent of Sb2O5 (based on the number of moles of Sb). In Example 6E, the procedure in Example 4E was repeated, with the Ta2O5·xH2O in the reaction replaced by a molar equivalent of Nb2O5·xH2O. In Example 7E, the procedure in Example 4E was repeated, with the TeO2 in the reaction replaced by a molar equivalent of Sb2O5 (based on the number of moles of Sb), and the Ta2O5·xH2O replaced by a molar equivalent of Nb2O5·xH2O. The masses of each sample after the drying and calcination steps are also shown in Table 3.

[0105] [Table 3]

[0106] <Preparation of Examples 8E to 10E> The procedures in Examples 2E to 4E were repeated with changes to the heating conditions. For each sample 8E to 10E, the autoclave was sealed and heated in an oven from room temperature to 180°C over 2 hours, then held at 180°C for 48 hours, after which the power was turned off and it was allowed to cool passively. The amount of reagent in Example 8E was the same as in Example 2E. The amount of reagent in Example 9E was the same as in Example 3E. The amount of reagent in sample 10E was the same as in Example 4E.

[0107] <Preparation of Example 11E> The procedure in Example 5E was repeated by scaling up the amount of reagents, as shown in Table 4.

[0108] [Table 4]

[0109] A modified heating profile was used. The autoclave was sealed and placed in an oven, heated from room temperature to 180°C over 24 hours, held at 180°C for 60 hours, then the power was turned off and it was passively cooled to room temperature. A portion of the sample was calcined (8.0872g before calcination, 7.5789g after calcination).

[0110] <Preparation of Example 12E> Example 12E was synthesized following the same procedure as described for samples 2E to 4E. The amounts of reagents used are shown in Table 5.

[0111] [Table 5]

[0112] All solid components were added to a blender and ground and blended with three 1-minute pulses. The solid mixture was then transferred to a 40 mL vial. Water was added and the mixture was stirred to form an orange slurry. This vial was then placed in a 2 L steel autoclave, and the outside of the vial was filled with water to improve heat transfer and maintain a relative humidity of 100% inside the container. The autoclave was sealed and heated in an oven from room temperature to 180°C for 12 hours. After maintaining the temperature at 180°C for 48 hours, the heating was stopped and the container was passively cooled to room temperature for approximately 6 hours.

[0113] After cooling, the autoclave was evacuated and the vial was removed. As the reaction progressed, the orange slurry turned into a dark purple solid. This solid was crushed and transferred to a vacuum filter, where it was washed with water until the filtrate was colorless and clear. Next, the dark purple solid was placed in an oven and dried overnight at 90°C. After drying, 32.2259 g of purple solid was obtained.

[0114] Next, the solid sample was calcined in a tubular quartz furnace under an N2 gas flow (linear velocity of 3.9 cm / min in STP). The solid was heated to 600°C at a rate of 1.6°C / min. After holding the temperature at 600°C for 2 hours, heating was stopped, and the solid was passively cooled to room temperature under an N2 gas flow for approximately 12 hours. A mass loss of 2.45% was observed after calcination. The PXRD pattern of the calcined sample is shown in Figure 6.

[0115] <Preparation of pelletized catalyst: Example 12E (pelletized)> A pelletized catalyst using an inert support was prepared using a portion of the calcined sample 12E. Catalyst sample 12E (10.0050 g), alpha alumina (10.0207 g), polyethylene glycol 1000 (0.3986 g), MOWIOL 8-88 (0.6095 g), and polyacrylic acid (0.0230 g) were added to a 1 L beaker containing 100 mL of water. The mixture was heated to 90°C using an oil bath and stirred with an overhead stirrer. Heating was continued until most of the water evaporated, leaving a thick purple paste. The beaker was then transferred to a 90°C oven and dried completely overnight, leaving a hard purple solid. This solid was crushed using a mortar and pestle and sieved to obtain granules with a diameter of 180–500 μm.

[0116] The granules were fed into an automatic press (Dott Bonapace CPR-6) and pressed into cylindrical pellets approximately 3 mm in diameter and 5 mm in length. The pellets were sintered in a tubular quartz furnace. First, they were heated to 400°C at a rate of 1.0°C / min under a dry air flow (linear velocity of 1.8 cm / min in STP), held at 400°C for 1 hour, and then passively cooled to room temperature over approximately 8 hours. Next, the flow rate in the quartz furnace was switched to nitrogen (linear velocity of 3.9 cm / min in STP), and after allowing sufficient time to completely purge the air in the furnace, the sample was heated from room temperature to 600°C at a rate of 1.6°C / min, held at 600°C for 2 hours, and then passively cooled to room temperature over approximately 12 hours. A mass loss of 5.24% was observed after the sintering process. The PXRD pattern of sample 12E (pelletized) is shown in Figure 7.

[0117] <Equipment and Measurement>

[0118] <Elemental analysis> The catalyst metal composition of calcined samples 3E-7E, 9E, and 11E was measured by energy-dispersive X-ray spectroscopy (EDX). EDX was performed using a JEOL JED-2300 DRY SDD EDX detector. EDX scans were performed on the largest rectangular area covered by the sample (approximately 2.8 mm × 2.1 mm, typically at a magnification of approximately 50x, but this may vary depending on the sample size and coverage). Data analysis software used was AnalysisStation from JEOL. Scans were performed at an accelerating voltage of 25 kV.

[0119] The catalytic chemical formula determined by EDX is shown in Table 6 below.

[0120] [Table 6]

[0121] <Powder X-ray Diffraction (PXRD)> Powder X-ray diffraction (PXRD) experiments were performed using a PANalytical Empyrean powder X-ray diffractometer equipped with a monochromator and CuKα-ray X-ray source. Data were acquired at a scan rate of 1° / min in the range of 3–80°²θ. The data were analyzed using PANalytical HighScore software version 4.8.

[0122] Powder X-ray diffraction (PXRD) analysis was performed on samples 2E to 4E after calcination (Figures 2 to 4, respectively). PXRD analysis characterized all three samples as a doped molybdenum vanadium oxide phase known as M1 in academic literature. Sample 2E contained a trace amount of impurity MoO3 (indicated by the arrow in Figure 1), while samples 3E (Figure 2) and 4E (Figure 3) were pure M1 phase. This analysis indicates that the synthesis procedure increases the crystalline purity of the catalytically active M1 phase.

[0123] Figure 4 shows the superposition of the PXRD patterns for Examples 5E to 7E. The PXRD characterization of sample 5E shows that even if TeO2 in this synthesis is replaced with a molar equivalent of Sb2O5 (based on the number of moles of Sb), a high-purity M1 phase and active catalyst can be produced. The PXRD characterization of sample 6E shows that even if Ta2O5·xH2O in this reaction is replaced with approximately equivalent amounts of Nb2O5·xH2O, a high-purity M1 phase can be produced. The PXRD characterization of sample 7E shows that even if both TeO2 and Ta2O5·xH2O are replaced, a high-purity M1 phase can be produced. Figure 5 shows the superposition of the PXRD patterns for samples 8E to 10E, showing that the M1 phase can be produced even with shorter heating / increasing times.

[0124] <Scanning Electron Microscope> Scanning electron microscope (SEM) images were collected using a JEOL-JSM300LV scanning electron microscope. Figures 8 to 14 show SEM images of samples 3E to 7E, 9E, and 11E.

[0125] <Catalyst Testing> The catalysts described herein were tested for their ability to catalyze the oxidative dehydrogenation (ODH) of ethane using a microreactor unit (MRU). The MRU consisted of a reactor tube made of stainless steel SWAGELOK® tubing, with an outer diameter of 0.5 inches (1.27 cm), an inner diameter of 0.4 inches (1.02 cm), and a length of 13.4–15 inches (34.0–38.1 cm). The experimental temperature of the MRU was measured by inserting a 6-point WIKA Instruments Ltd. K-type thermocouple with an outer diameter of 0.125 inches (0.318 cm) into the reactor. This 6-point thermocouple was used to measure and control the temperature within the catalyst bed. A stainless steel condenser at room temperature was placed after the reactor to collect the water / acetic acid condensate. If product gas analysis was required, the gas product flow was either evacuated or directed to an Agilent 8890 "hot gas" gas chromatograph (HGGC).

[0126] The sample was compressed into pellets using a steel die and a hydraulic press, then the pellets were crushed, and particles with a size of 425-710 μm were sieved and loaded into the MRU. Approximately 2 g of the sample was placed in the reactor. In the case of 12E (pelletized), the pelletized sample was crushed using a mortar and pestle, and granules with a size of 425-710 μm were sieved and loaded into the MRU. Approximately 4 g of crushed sample was placed in the reactor to load approximately 2 g of catalyst phase. After loading the catalyst bed into the reactor and connecting it to the MRU apparatus, the test was carried out as described herein.

[0127] The catalyst bed was loaded into the intermediate zone of the reactor, and quartz sand was loaded into the remaining volume of the reactor to bring the catalyst bed volume to 6 mL, ensuring a sufficient catalyst volume to cover the thermocouple area between points 2 and 5. The materials loaded into the reactor were then secured with glass wool from both the top and bottom of the reactor. Additional quartz sand was added to bring the catalyst bed volume to 6 mL, ensuring a sufficient catalyst volume to cover the thermocouple area.

[0128] The gas supply flow rate is set to the target value of 150 sccm (space velocity per hour (WHSV) = 3.57 h). -1 The gas flow rate was adjusted to ). As used herein, the expression "space velocity per second of weight" refers to the total feed gas flow rate divided by the weight of the catalyst. In all tests, the target gas feed composition was 20 mol% ethane, 10 mol% oxygen, and 70 mol% nitrogen. The gas composition was determined by gas chromatography (GC) using an Agilent 6890N gas chromatograph, and the data was analyzed using Chrom Perfect-Analysis version 6.1.10. The samples were left in the flow at a temperature of 380-420°C for approximately 5 days until the data reached equilibrium.

[0129] The ethane conversion temperature in mol% is 3.57h for WHSV. -1 , gas space velocity per hour (GHSV) is 2000-5000 h -1The range was determined. Gaseous products discharged from the catalyst bed were exhausted during operation. When analyzing the gaseous products, they were temporarily redirected to a gas chromatograph to determine the proportions of ethane, ethylene, O2, CO2, CO, and optionally acetic acid. The gas discharged from the reactor was analyzed by gas chromatography. The conversion rate (C) of the ethane feed gas was calculated as the change in volume flow rate of ethane in the product compared to the feed ethane mass flow rate, using the following formula:

number

[0130] In Equation 1, X is the molar concentration of the corresponding compound in the gaseous effluent discharged from the reactor at the corresponding temperature. Since the molar concentration of acetic acid could not be measured at the time, it was assumed to be 0 mol%.

[0131] The gas emitted from the reactor was analyzed by GC to measure the selectivity of the catalyst or catalytic material to ethylene (i.e., the molar ratio of ethane that produces ethylene). Selectivity to ethylene (S エチレン ) was determined using the following formula:

number

[0132] In equation 2 above, S エチレン is the selectivity for ethylene, and X is the molar concentration of the corresponding compound in the gaseous effluent discharged from the reactor at the corresponding temperature. The molar concentration of acetic acid could not be measured at the time, so it was assumed to be 0 mol%. Therefore, the selectivity is reported as the combined selectivity of ethylene and acetic acid.

[0133] <Overview of catalyst performance> The results for comparative sample 1C, example 3E, and examples 5E to 11E are summarized in Table 7.

[0134] [Table 7]

[0135] As can be seen, samples 3E, 5E, and 8E-10E show higher activity and ethane conversion rates compared to sample 1C, and slightly lower selectivity for the combined ethylene and acetic acid (Table 7). Sample 11E showed improved activity and selectivity at lower temperatures compared to sample 1C. Furthermore, at approximately the same ethane conversion rate (%) as sample 1C, sample 11E showed a selectivity of 96.6% for the combined ethylene and acetic acid at 370°C (ethane conversion rate 25.4%). Therefore, the synthesis method disclosed herein can produce high-quality, active catalysts using significantly less water.

[0136] Figure 15 plots the ethane conversion rates of comparative catalyst 1C, calcined sample 3E, and calcined samples 8E-10E. Figure 16 plots the combined selectivity of ethylene and acetic acid produced by comparative catalyst 1C, calcined sample 3E, and calcined samples 8E-10E. Figure 17 plots the ethane conversion rates of comparative catalyst 1C, calcined sample 5E, and calcined sample 11E. Figure 18 plots the combined selectivity of ethylene and acetic acid produced by comparative catalyst 1C, calcined sample 5E, and calcined sample 11E. As shown in Figures 15 and 17, samples 3E, 5E, 8E-10E, and 11E showed higher ethane conversion rates (%) at lower temperatures than comparative sample 1C.

[0137] Table 8 shows the performance of the catalyst in Example 12E (pellet form). This data demonstrates that the compound catalyst prepared by the method disclosed herein is highly active for ethane ODH even at high ethane conversion rates and has high selectivity for value-added products (ethylene and acetic acid).

[0138] [Table 8]

[0139] Non-limiting embodiments of this disclosure include:

[0140] Embodiment A. A method for preparing a catalyst, comprising the steps of forming a slurry containing a metal oxide, a reducing agent, and water, and heating the slurry to form a catalyst, wherein the metal oxide includes molybdenum oxide, vanadium oxide, tellurium oxide, or antimony oxide, or both, and tantalum oxide or niobium oxide, and the ratio of water in the slurry to the amount of catalyst formed is in the range of 0.1 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

[0141] Embodiment B. The method according to Embodiment A, wherein the ratio of water in the slurry to the amount of catalyst formed is in the range between 0.2 mL of water per gram of catalyst and 1 mL of water per gram of catalyst.

[0142] Embodiment C. The method according to Embodiment A or B, wherein the slurry has a water-to-metal oxide ratio in the range of 0.2 mL of water per gram of metal oxide and 0.6 mL of water per gram of metal oxide.

[0143] Embodiment D. The method according to Embodiment A or B, wherein the slurry has a water-to-metal oxide ratio in the range between 0.3 mL of water per gram of metal oxide and 0.5 mL of water per gram of metal oxide.

[0144] Embodiment E. The method according to Embodiments A, B, C, or D, wherein the molybdenum oxide is MoO3.

[0145] Embodiment F. The method according to Embodiments A, B, C, D, or E, wherein the vanadium oxide is V2O5.

[0146] Embodiment G. The method according to Embodiments A, B, C, D, E, or F, wherein if tellurium oxide is present, it is TeO2, and if antimony oxide is present, it is Sb2O5.

[0147] Embodiment H. The method according to Embodiments A, B, C, D, E, F, or G, wherein if tantalum oxide is present, it is Ta2O5·xH2O, and if niobium oxide is present, it is Nb2O5·xH2O.

[0148] Embodiment I. The method according to Embodiments A, B, C, D, E, F, G, or H, further comprising the step of crushing, wet crushing, dry crushing, or pulverizing a metal oxide.

[0149] Embodiment J. The method according to Embodiments A, B, C, D, E, F, G, H, or I, further comprising the steps of grinding, wet grinding, dry grinding, or crushing a metal oxide and a reducing agent.

[0150] Embodiment K. The method according to Embodiments A, B, C, D, E, F, G, H, I, or J, wherein the reducing agent comprises an alcohol, a carboxylic acid, or an ester.

[0151] Embodiment L. The method according to Embodiments A, B, C, D, E, F, G, H, I, J, or K, wherein the reducing agent is oxalic acid or ethanol.

[0152] Embodiment M. The method according to Embodiments A, B, C, D, E, F, G, H, I, J, K, or L, wherein the reducing agent is oxalic acid.

[0153] Embodiment N. The method according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, or M, wherein the slurry contains one or less reducing agents.

[0154] Embodiment O. A method according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or N, comprising the step of heating a slurry by raising the temperature from ambient temperature to a temperature of 100°C to 200°C over a heating time of 2 hours to 48 hours, and holding the temperature at a holding temperature of 100°C to 200°C for a holding time of 12 hours to 120 hours.

[0155] Embodiment P. The method according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, or O, further comprising the step of washing the catalyst with water.

[0156] Embodiment Q. The method according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, or P, further comprising the step of calcining a catalyst to form a calcined catalyst.

[0157] Embodiment R. A method according to Embodiment Q, comprising the steps of calcining a catalyst by placing the catalyst in a furnace in an oxygen-free environment, raising the furnace temperature from ambient temperature to a temperature of 500°C to 620°C over a heating time of 2 to 10 hours, and maintaining the furnace temperature at a holding temperature of 500°C to 620°C for a holding time of 1 to 10 hours.

[0158] Embodiment S. The method according to Embodiment Q or R, wherein the ratio of water in the slurry to the amount of calcined catalyst formed is less than 1 mL of water per gram of calcined catalyst.

[0159] Embodiment T. The method according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, or S, wherein the catalyst is Mo a V b Te c Ta d O x Mo a V b S c Ta d O x Mo a V b Te c Nb d O x , and Mo a V b S c Nb d O xA method comprising a formula selected from, where a is 1.0, b is 0.01 to 0.4, c is 0.01 to 0.2, d is 0.01 to 0.10, x is the number of oxygen atoms required to make the catalyst electrically neutral, and a, b, c, and d are determined based on the amount of each metal oxide added to the slurry.

[0160] Embodiment U. The method according to Embodiment T, wherein the values ​​of a, b, c, and d are also determined by elemental analysis.

[0161] Embodiment V. The method according to Embodiment T or U, wherein b is 0.2 to 0.4, c is 0.03 to 0.07, and d is 0.01 to 0.06.

[0162] Embodiment W. The catalyst is Mo1V 0.31 Te 0.05 Ta 0.05 O x Mo1V 0.31 S 0.05 Ta 0.05 O x Mo1V 0.31 Te 0.05 Nb 0.05 O x , and Mo1V 0.31 S 0.05 Nb 0.05 O x The method according to embodiment T, U, or V, having an expression selected from the following.

[0163] Embodiment X. The catalyst is Mo1V 0.32 Te 0.05 Ta 0.02 O x Mo1V 0.32 S 0.05 Ta 0.02 O x Mo1V 0.31 Te 0.04 Nb 0.02 O x Mo1V 0.30 S 0.05 Nb 0.02 O x Mo1V 0.34 Te 0.05 Ta0.02 , Mo1V 0.34 Te 0.06 Ta 0.02 , Mo1V 0.34 Sb 0.06 Ta 0.02 , Mo1V 0.34 Te 0.05 Nb 0.01 , Mo1V 0.32 Sb 0.06 Nb 0.02 , and Mo1V 0.34 Sb 0.05 Ta 0.03 having a formula selected from, and each formula being determined by energy-dispersive X-ray spectroscopy (EDX), the method according to embodiment T or U.

[0164] Embodiment Y. The method according to embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, or X, wherein the metal oxide has a particle size distribution in the range of 0.5 μm to 250 μm.

[0165] Embodiment Z. The method according to embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, or Y, wherein the ratio of the total amount of water used to prepare the catalyst is in the range between 0.2 mL of water per gram of catalyst and 25 mL of water per gram of catalyst.

[0166] Embodiment AA. The method according to embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, or Z, wherein the ratio of the total amount of water used to prepare the catalyst is in the range between 0.2 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

[0167] Other embodiments are also included within the scope of the claims.

Claims

1. A method for preparing a catalyst, A step of forming a slurry containing a metal oxide, a reducing agent, and water, The process includes the step of heating the slurry to form a catalyst, Metal oxides are, Molybdenum oxide, Vanadium oxide, Tellurium oxide or antimony oxide or both, and It contains tantalum oxide or niobium oxide or both. The method involves a ratio of water in the slurry to the amount of catalyst formed, which is in the range between 0.1 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

2. The method according to claim 1, wherein the ratio of water in the slurry to the amount of catalyst formed is in the range between 0.2 mL of water per gram of catalyst and 1 mL of water per gram of catalyst.

3. The method according to claim 1, wherein the slurry has a water-to-metal oxide ratio in the range between 0.2 mL of water per gram of metal oxide and 0.6 mL of water per gram of metal oxide.

4. The method according to claim 1, wherein the slurry has a water-to-metal oxide ratio in the range between 0.3 mL of water per gram of metal oxide and 0.5 mL of water per gram of metal oxide.

5. Molybdenum oxide is MoO ３ The method according to claim 1.

6. Vanadium oxide is V ２ O ５ The method according to claim 1.

7. If tellurium oxide is present, TeO ２ And if antimony oxide is present, Sb ２ O ５ The method according to claim 1.

8. When tantalum oxide is present, Ta ２ O ５ ·xH ２ O, and when niobium oxide is present, Nb ２ O ５ ·xH ２ O, the method according to claim 1.

9. The method according to claim 1, further comprising the steps of crushing, wet crushing, dry crushing, or pulverizing a metal oxide.

10. The method according to claim 1, further comprising the steps of grinding, wet grinding, dry grinding, or crushing a metal oxide and a reducing agent.

11. The method according to claim 1, wherein the reducing agent comprises an alcohol, a carboxylic acid, or an ester.

12. The method according to claim 11, wherein the reducing agent is oxalic acid or ethanol.

13. The method according to claim 11, wherein the reducing agent is oxalic acid.

14. The method according to claim 1, wherein the slurry contains one or less reducing agents.

15. The method according to claim 1, The temperature is raised from the ambient temperature to a temperature of 100°C to 200°C over a heating time of 2 hours to 48 hours, and Maintain the temperature at a holding temperature of 100°C to 200°C for a holding time of 12 to 120 hours. A method comprising the step of heating a slurry.

16. The method according to claim 1, further comprising the step of washing the catalyst with water.

17. The method according to claim 1, further comprising the step of calcining a catalyst to form a calcined catalyst.

18. The method according to claim 17, The catalyst is placed inside a furnace in an oxygen-free environment. The furnace temperature is raised from the ambient temperature to a temperature of 500°C to 620°C over a heating time of 2 to 10 hours, and The furnace temperature is maintained at a holding temperature of 500°C to 620°C for a holding time of 1 to 10 hours. A method comprising the step of calcining a catalyst.

19. The method according to claim 17, wherein the ratio of water in the slurry to the amount of calcined catalyst formed is less than 1 mL of water per gram of calcined catalyst.

20. The method according to claim 1, wherein the catalyst is Mo ａ V ｂ Te ｃ Ta ｄ O ｘ Mo ａ V ｂ Sb ｃ Ta ｄ O ｘ Mo ａ V ｂ Te ｃ Nb ｄ O ｘ , and Mo ａ V ｂ Sb ｃ Nb ｄ O ｘ Composed of expressions selected from, a is 1.0, b is between 0.01 and 0.

4. c is between 0.01 and 0.

2. d is between 0.01 and 0.

10. x is the number of oxygen atoms required to make the catalyst electrically neutral. a, b, c, and d are determined based on the amount of each metal oxide added to the slurry, in a method.

21. The method according to claim 20, wherein the values ​​of a, b, c, and d are also determined by elemental analysis.

22. b is between 0.2 and 0.4, c is between 0.03 and 0.07, d is between 0.01 and 0.

06. The method according to claim 20.

23. The catalyst is Mo １ V ０．３１ Te ０．０５ Ta ０．０５ O ｘ Mo １ V ０．３１ Sb ０．０５ Ta ０．０５ O ｘ Mo １ V ０．３１ Te ０．０５ Nb ０．０５ O ｘ , and Mo １ V ０．３１ Sb ０．０５ Nb ０．０５ O ｘ The method according to claim 20, comprising an expression selected from.

24. The catalyst is Mo １ V ０．３２ Te ０．０５ Ta ０．０２ O ｘ 、Mo １ V ０．３２ Sb ０．０５ Ta ０．０２ O ｘ 、Mo １ V ０．３１ Te ０．０４ Nb ０．０２ O ｘ 、Mo １ V ０．３０ Sb ０．０５ Nb ０．０２ O ｘ 、Mo １ V ０．３４ Te ０．０５ Ta ０．０２ 、Mo １ V ０．３４ Te ０．０６ Ta ０．０２ 、Mo １ V ０．３４ Sb ０．０６ Ta ０．０２ 、Mo １ V ０．３４ Te ０．０５ Nb ０．０１ 、Mo １ V ０．３２ Sb ０．０６ Nb ０．０２ 、and Mo １ V ０．３４ Sb ０．０５ Ta ０．０３ having a formula selected from, and each formula being determined by energy dispersive X-ray spectroscopy (EDX), the method according to claim 21.

25. The method according to claim 1, wherein the metal oxide has a particle size distribution in the range of 0.5 μm to 250 μm.

26. The method according to claim 1, wherein the ratio of the total amount of water used to prepare the catalyst is in the range between 0.2 mL of water per gram of catalyst and 25 mL of water per gram of catalyst.

27. The method according to claim 1, wherein the ratio of the total amount of water used to prepare the catalyst is in the range between 0.2 mL of water per gram of catalyst and 10 mL of water per gram of catalyst.

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