JP2022181492A - Oxidative dehydrogenation catalyst - Google Patents

Abstract

To provide an oxidative dehydrogenation catalyst that has a higher activity and a longer life compared to the conventional catalysts, and is for producing propylene through an oxidative dehydrogenation reaction of propane.SOLUTION: An oxidative dehydrogenation catalyst is for producing propylene through an oxidative dehydrogenation reaction of propane. The oxidative dehydrogenation reaction is conducted by reacting propane with carbon dioxide. The oxidative dehydrogenation catalyst has active ingredients being supported on a ceria carrier. The active ingredients include a platinum element, an indium element, and a 3d-transition metal element.SELECTED DRAWING: None

Description

Patent Law Article 30, Paragraph 2 application filed [1] Publication date (publication date) September 9, 2020 Publications 126th Catalysis Symposium Proceedings Published by The Catalysis Society of Japan Participant-only proceedings download [2] Date (release date) September 16, 2020 (session: September 16-18, 2020) Meeting name, venue The 126th Catalysis Symposium Video conference system ( Hosted by the Catalysis Society of Japan <Document> Overview of the 126th Catalysis Symposium <Document> 126th Catalysis Symposium Proceedings Research Summary <Document> 126th Catalysis Symposium Program <Document> 126th Catalysis Symposium presentation materials

The present invention relates to an oxidative dehydrogenation catalyst.

Propylene is a key chemical for manufacturing various chemicals such as resins, surfactants, dyes, and pharmaceuticals. In recent years, the feedstock for steam crackers has shifted from naphtha derived from crude oil to ethane derived from shale gas, which has reduced the supply of propylene.

Against this background, the production of propylene by a simple dehydrogenation reaction of propane has attracted attention. A simple dehydrogenation reaction of propane proceeds according to the reaction formula represented by Formula 1 below. Since the simple dehydrogenation reaction of propane is an endothermic reaction, a high temperature of 600° C. or higher is required for the progress of the reaction.
_{C3H8 → C3H6 + H2} Formula 1

An oxidative dehydrogenation reaction of propane using carbon dioxide as an oxidizing agent has been studied as an attempt to improve the equilibrium conversion rate of the dehydrogenation reaction of propane. The oxidative dehydrogenation reaction of propane proceeds according to the reaction formula represented by Formula 2 below.
_{C3H8 + CO2} → _C3H6 + _H2O +CO _Formula 2

In the oxidative dehydrogenation reaction of propane, the equilibrium can be shifted to the product side by oxidizing the hydrogen generated in the dehydrogenation reaction of propane with carbon dioxide to produce water. Equilibrium conversion is improved over dehydrogenation.

Extensive research has been conducted on propane oxidative dehydrogenation catalysts, including chromium oxide-based catalysts, vanadium oxide-based catalysts, gallium oxide-based catalysts, indium oxide-based catalysts, palladium metal-based catalysts, and iron-nickel alloy-based catalysts. Catalysts are known.

Non-Patent Documents 1 and 2 disclose a chromium oxide-based propane oxidative dehydrogenation catalyst in which chromium oxide is supported on a mesoporous silica carrier. Further, it is disclosed that a good propylene selectivity (about 80%) was exhibited by using a chromium oxide-based catalyst for oxidative dehydrogenation of propane.

Baek, J., Yun, H. J., Yun, D., Choi, Y. & Yi, J. ACS Catal. 2, 1893-1903 (2012). Wang, H. M., Chen, Y., Yan, X., Lang, W. Z. & Guo, Y. J. Microporous Mesoporous Mater. 284, 69-77 (2019).

However, the activity of the propane oxidative dehydrogenation catalysts described in Non-Patent Documents 1 and 2 is not sufficient. In addition, the propane oxidative dehydrogenation catalysts described in Non-Patent Documents 1 and 2 have a low conversion rate of carbon dioxide. Furthermore, there is a problem that the activity rapidly decreases within several hours.
The present invention has been made in view of the above circumstances, and provides an oxidative dehydrogenation catalyst for producing propylene by the oxidative dehydrogenation reaction of propane, which has higher activity and longer life than conventional catalysts. The task is to provide

In order to solve the above problems, the present invention has the following aspects.
[1] An oxidative dehydrogenation catalyst for producing propylene by an oxidative dehydrogenation reaction of propane, wherein the oxidative dehydrogenation reaction is performed by reacting propane with carbon dioxide, and the oxidative dehydrogenation catalyst is A catalyst for oxidative dehydrogenation, wherein an active component is supported on a ceria carrier, and the active component comprises a platinum element, an indium element, and a 3d transition metal element.
[2] The oxidative dehydrogenation catalyst according to [1], wherein the 3d transition metal element is one or more elements selected from the group consisting of cobalt elements and nickel elements.
[3] The oxidative dehydrogenation catalyst according to [1] or [2], wherein the 3d transition metal element is a cobalt element.
[4] The oxidative dehydrogenation catalyst according to any one of [1] to [3], wherein the platinum element, the indium element, and the 3d transition metal element form an alloy.

According to the present invention, it is possible to provide an oxidative dehydrogenation catalyst for producing propylene by the oxidative dehydrogenation reaction of propane, which has a higher activity and a longer life than conventional catalysts.

FIG. 2 is a diagram showing the equilibrium conversion rate at normal pressure of a simple dehydrogenation reaction of propane and an oxidative dehydrogenation reaction of propane. 1 is a diagram showing the crystal structure (unit cell) of a platinum-indium-cobalt alloy; FIG. FIG. 2 is a graph showing temporal changes in propane conversion and propylene selectivity in the oxidative dehydrogenation reaction of propane using the oxidative dehydrogenation catalysts of Example 1 and Comparative Examples 1 to 4. FIG. FIG. 2 is a graph showing changes over time in the conversion rate of carbon dioxide in the oxidative dehydrogenation reaction of propane using the oxidative dehydrogenation catalysts of Example 1 and Comparative Examples 1 to 4. FIG. FIG. 2 is a graph showing temporal changes in the conversion rate of propane and carbon dioxide in the oxidative dehydrogenation reaction of propane using the oxidative dehydrogenation catalyst of Example 2, and a graph showing temporal changes in selectivity for propylene and by-products. . FIG. 3 is a graph showing temporal changes in the conversion rate of propane and carbon dioxide in the oxidative dehydrogenation reaction of propane using the oxidative dehydrogenation catalyst of Example 3, and a graph showing temporal changes in selectivity for propylene and by-products. . FIG. 2 is a graph showing temporal changes in the conversion rate of propane and the conversion rate of carbon dioxide in the oxidative dehydrogenation reaction of propane using the oxidative dehydrogenation catalysts of Example 1 and Comparative Examples 5 to 7. FIG. FIG. 2 is a diagram showing temporal changes in the conversion rate of propane in a life test (including regeneration treatment) of the oxidative dehydrogenation reaction of propane using the oxidative dehydrogenation catalyst of Example 1, and a diagram showing temporal changes in the conversion rate of carbon dioxide. be.

Embodiments of the present invention will be described in detail below, but the following description is an example of the embodiments of the present invention, and the present invention is not limited to these contents, and can be modified within the scope of the gist thereof. can do.

≪Catalyst for oxidative dehydrogenation≫
The oxidative dehydrogenation catalyst of the present embodiment is an oxidative dehydrogenation catalyst for producing propylene by an oxidative dehydrogenation reaction of propane. The oxidative dehydrogenation reaction can be carried out by reacting propane with carbon dioxide. The oxidative dehydrogenation catalyst has an active component supported on a ceria carrier. The oxidative dehydrogenation catalyst contains a platinum element, an indium element, and a 3d transition metal element as the active components.

<Active ingredient>
The oxidative dehydrogenation catalyst contains a platinum element, an indium element, and a 3d transition metal element as active components.

When the platinum element is included as an active component, propane can be activated and the propane conversion rate is improved. When a 3d transition metal element is included as an active component, carbon dioxide can be activated, and the conversion rate of carbon dioxide is improved. When the indium element is included as an active component, side reactions such as coke formation can be suppressed, and the yield of propylene is improved. In addition, by suppressing coke formation, deterioration in catalytic activity over time is suppressed.

The 3d transition metal elements include scandium elements, titanium elements, vanadium elements, chromium elements, manganese elements, iron elements, cobalt elements, nickel elements, and copper elements. Among these, the cobalt element and the nickel element are preferable, and the cobalt element is more preferable, from the viewpoint of high activating ability of carbon dioxide.

The mechanism by which the 3d transition metal element activates carbon dioxide is thought to be due to the strong adsorption of carbon dioxide by the 3d transition metal.

The molar ratio of the platinum element to the indium element (Pt/In) in the oxidative dehydrogenation catalyst is preferably 0.3 to 0.7, more preferably 0.4 to 0.6, and 0 0.5 is more preferred. When Pt/In is at least the lower limit of the above range, propylene selectivity and catalyst life are improved. When the Pt/In is equal to or less than the upper limit of the above range, the propane conversion is less likely to decrease.

In the oxidative dehydrogenation catalyst, the molar ratio of the platinum element to the 3d transition metal element (Pt/3d metal) is preferably 0.8 to 1.2, more preferably 0.9 to 1.1. Preferably, it is more preferably 1.0. When the Pt/3d metal is at or above the lower end of the range, propane conversion increases. When the Pt/3d metal content is equal to or less than the upper limit of the above range, the conversion of carbon dioxide does not decrease.

In the oxidative dehydrogenation catalyst, the molar ratio of the indium element to the 3d transition metal element (In/3d metal) is preferably 1.8 to 2.2, more preferably 1.9 to 2.1. Preferably, it is more preferably 2.0. When the In/3d metal is at least the lower limit of the above range, propylene selectivity and catalyst life are improved. When the In/3d metal is equal to or less than the upper limit of the above range, the propane conversion is less likely to decrease.

In the oxidative dehydrogenation catalyst, the molar ratio of the platinum element to the sum of the indium element and the 3d transition metal element (Pt/(In+3d metal)) is preferably 0.3 to 0.4, and 0.31 to 0. 0.35 is more preferred, and 0.33 is even more preferred. When (Pt/(In+3d metal)) is equal to or higher than the lower limit of the range, the propane conversion increases. When (Pt/(In+3d metal)) is equal to or less than the upper limit value of the above range, the propane conversion is less likely to decrease.

In the oxidative dehydrogenation catalyst, the molar ratio of the indium element to the sum of the platinum element and the 3d transition metal element (In/(Pt+3d metal)) is preferably 0.8 to 1.2, more preferably 0.9 to 1 .1 is more preferred, and 1.0 is even more preferred. When (In/(Pt+3d metal)) is at least the lower limit of the above range, propylene selectivity and catalyst life are improved. When (In/(Pt+3d metal)) is equal to or less than the upper limit value of the above range, the propane conversion is less likely to decrease.

In the oxidative dehydrogenation catalyst, the molar ratio of the 3d transition metal element to the total of the platinum element and the indium element (3d transition metal element/(Pt+In)) is preferably 0.3 to 0.4, and 0.31. ~0.35 is more preferred, and 0.33 is even more preferred. When (3d transition metal element/(Pt+In)) is equal to or higher than the lower limit of the range, the conversion rate of carbon dioxide increases. When (3d transition metal element/(Pt+In)) is equal to or less than the upper limit of the above range, propylene selectivity and catalyst life are less likely to decrease.

In the active component of the oxidative dehydrogenation catalyst, the form of the platinum element, indium element, and 3d transition metal element is not particularly limited, and metals, oxides, and alloys can be cited as examples. Among them, it is preferable that two or more of the platinum element, the indium element, and the 3d transition metal element form an alloy, and the platinum element, the indium element, and the 3d transition metal element form an alloy. is more preferred. That is, the active component preferably contains a platinum-indium-3d metal alloy (hereinafter also referred to as "three-element alloy"). The content of the three-element alloy with respect to the total mass of the active ingredients is preferably 50-100% by mass, more preferably 75-100% by mass, and even more preferably 100% by mass.

The three-element alloy of this embodiment preferably has a structure in which part of platinum in the Pt ₂ In ₃ alloy is replaced with a 3d metal. FIG. 2 shows the crystal structure (unit cell) of a platinum-indium-cobalt alloy in which the 3d metal is cobalt.

In the case of having the crystal structure shown in FIG. 2, in the X-ray diffraction pattern, part of the platinum of the Pt ₂ In ₃ alloy is replaced with a 3d metal at the position of 2θ = 39.5 to 40.5 °. peak is confirmed.
The XRD pattern of the oxidative dehydrogenation catalyst can be obtained by powder X-ray diffraction measurement using CuKα as a radiation source. For example, an XRD pattern of a powdery oxidative dehydrogenation catalyst can be obtained using an X-ray diffractometer (eg, MiniFlex II/AP manufactured by Rigaku Corporation).

The average particle size of the three-element alloy is preferably 15 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less. When the average particle size of the three-element alloy is equal to or less than the upper limit of the above range, the conversion rate of propane and carbon dioxide increases. Although the lower limit of the average particle size is not particularly limited, it may be 1 nm or more, 1.5 nm or more, or 2 nm or more. The average particle size is preferably 1 to 15 nm, more preferably 1 to 5 nm, even more preferably 1 to 3 nm. The average particle size of the three-element alloy can be measured with a transmission electron microscope (TEM). A specific method for measuring the average particle size of the three-element alloy will be described in Examples below.

<Ceria carrier>
In the oxidative dehydrogenation reaction of propane, coke is produced as a side reaction. When the coke produced on the oxidative dehydrogenation catalyst accumulates, the catalytic activity is lowered. In the oxidative dehydrogenation catalyst of the present embodiment, the lattice carbon of the ceria carrier burns the coke, thereby suppressing a decrease in catalytic activity.

As used herein, the term "ceria carrier" means a carrier containing 50% by mass or more of ceria relative to the total mass of the carrier. The content of ceria in the ceria carrier is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, even more preferably 100% by mass.

The ceria support may contain oxides other than ceria. Examples of oxides other than ceria include alumina, silica, zirconia, titania, magnesia, and the like. relative to the total weight of the ceria carrier. The content of oxides other than ceria is preferably 0 to 50% by mass, preferably 0 to 20% by mass, and more preferably not contained.

The BET specific surface area of the ceria carrier due to nitrogen adsorption is preferably 20 m ² /g or more, more preferably 50 m ² /g or more, and even more preferably 100 m ² /g or more. When the specific surface area of the ceria carrier is at least the above lower limit, the physical properties of the catalyst for oxidative dehydrogenation, which will be described later, are likely to be obtained. Although the upper limit of the BET specific surface area is not particularly limited, it may be 200 m ² /g or less. The BET specific surface area is preferably 20 to 200 m ² /g, more preferably 50 to 200 m ² /g, even more preferably 100 to 200 m ² /g.
As used herein, the "BET specific surface area" can be measured by nitrogen adsorption measurement.

(Supported amount of active ingredient)
The content ratio of the active component with respect to the total mass of the oxidative dehydrogenation catalyst is preferably 1.2 to 23% by mass, more preferably 2.3 to 12% by mass, and 3.3 to 6.0%. % by mass is more preferred. When the content of the active ingredient is at least the lower limit of the above range, the conversion of propane and the conversion of carbon dioxide increase. When the content of the active ingredient is equal to or less than the upper limit of the above range, the propane conversion rate and the carbon dioxide conversion rate are less likely to decrease.

The content ratio of the platinum element with respect to the total mass of the oxidative dehydrogenation catalyst is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, and 2 to 3% by mass. is more preferred. When the platinum element content is at least the lower limit of the above range, the propane conversion rate and the carbon dioxide conversion rate increase. When the platinum element content is equal to or less than the upper limit of the above range, the propane conversion rate and the carbon dioxide conversion rate are less likely to decrease.

The content of the indium element with respect to the total mass of the oxidative dehydrogenation catalyst is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, and 1 to 2% by mass. is more preferred. When the content of the indium element is equal to or higher than the lower limit of the above range, the propylene selectivity increases. When the content of indium element is equal to or less than the upper limit of the above range, the conversion of propane and the conversion of carbon dioxide do not decrease.

The content of the 3d transition metal element with respect to the total mass of the oxidative dehydrogenation catalyst is preferably 0.2 to 3% by mass, more preferably 0.3 to 2% by mass, and 0.3 to More preferably, it is 1% by mass. When the content of the 3d transition metal element is at least the lower limit of the above range, the carbon dioxide conversion rate and catalyst life are improved. When the content of the 3d transition metal element is equal to or less than the upper limit of the above range, the propylene selectivity is less likely to decrease.

In this specification, the content ratio of "platinum element, indium element, 3d transition metal element" can be measured by inductively coupled plasma atomic emission spectrometry (ICP). For example, after dissolving the oxidative dehydrogenation catalyst in aqua regia, the amount of each metal can be measured using an inductively coupled plasma emission spectrometer.

The degree of dispersion of the platinum element and the 3d transition metal element measured by CO adsorption of the oxidative dehydrogenation catalyst is preferably 5% or more, more preferably 10% or more, and preferably 20% or more. More preferred. When the degree of dispersion is at least the lower limit of the above range, the conversion of propane and carbon dioxide increases. Although the upper limit of the dispersity is not particularly limited, it may be 50% or less, 40% or less, or 30% or less. The dispersity is preferably 5 to 50%, more preferably 10 to 40%, even more preferably 20 to 30%. The degree of dispersion of the platinum element and the 3d transition metal element is the ratio of platinum and cobalt exposed on the surface to the total amount (100%) of platinum and cobalt contained in the oxidative dehydrogenation catalyst.
Specifically, the degree of dispersion can be calculated by the method described in Examples below.

(Physical properties of oxidative dehydrogenation catalyst)
The BET specific surface area by nitrogen adsorption of the oxidative dehydrogenation catalyst is preferably 20 m ² /g or more, more preferably 50 m ² /g or more, and even more preferably 100 m ² /g or more. When the specific surface area of the oxidative dehydrogenation catalyst is at least the lower limit of the above range, the propane conversion rate and the carbon dioxide conversion rate increase. Although the upper limit of the BET specific surface area is not particularly limited, it may be 200 m ² /g or less. The BET specific surface area is preferably 20 to 200 m ² /g, more preferably 50 to 200 m ² /g, even more preferably 100 to 200 m ² /g.

<<Method for producing oxidative dehydrogenation catalyst>>
The method for producing an oxidative dehydrogenation catalyst according to the present embodiment includes an impregnation step of impregnating a ceria carrier with an impregnation solution containing a raw material compound of the active ingredient to obtain an impregnated body, and reduction firing of the impregnated body in a reducing gas atmosphere. and a reduction firing step.

<Impregnation process>
A raw material compound containing a platinum element, a raw material compound containing an indium element, and a raw material compound containing a 3d transition metal element used in the impregnation step (hereinafter, all raw material compounds are also collectively referred to as "active ingredient raw material compounds"). As is not particularly limited, for example, inorganic salts such as chlorides, sulfides, nitrates, carbonates; organic salts such as oxalates, acetylacetonate salts, dimethylglyoxime salts, ethylenediamine acetate; chelate compounds carbonyl compounds; cyclopentadienyl compounds; ammine complexes; alkoxide compounds;

As the impregnation method, the ceria carrier is immersed in an excess impregnation solution with respect to the total pore volume of the ceria carrier, and then all the solvent is dried in the drying step described later, thereby carrying the raw material compound of the active ingredient. In the drying method, the ceria carrier is immersed in an impregnating solution that is excessive with respect to the total pore volume of the ceria carrier, followed by solid-liquid separation such as filtration, and then drying the solvent to support the raw material compound of the active ingredient. Equilibrium adsorption method for obtaining a catalyst, the ceria carrier is impregnated with an impregnating solution of approximately the same amount as the total pore volume of the ceria carrier, and in the drying step described later, the solvent is completely dried to support the raw material compound of the active ingredient. An example is a pore-filling method that As a method for impregnating the ceria carrier with raw material compounds of two or more active components, a batch impregnation method in which these components are impregnated simultaneously or a sequential impregnation method in which these components are impregnated individually may be used.

The impregnating liquid can be prepared by dissolving the raw material compound of the active ingredient in a solvent. The solvent is not particularly limited as long as it is capable of dissolving the raw material compound of the active ingredient and is removed by volatilization in the drying step described below. Examples thereof include water, ethanol, and acetone.

The drying of the solvent in the impregnating liquid can be performed by a method known in the art, and the drying temperature, drying time, and drying atmosphere can be appropriately adjusted depending on the solvent to be removed.

Hydrogen, carbon monoxide, and the like can be used as the reducing gas in the reduction firing step, and a gas diluted with an inert gas may be used. The temperature of reduction firing is preferably 400 to 700.degree. C., more preferably 500 to 700.degree. C., and preferably 600.degree.
The reduction firing time may be 1 to 2 hours, 1 to 3 hours, or 1 to 5 hours.

Between the impregnation step and the reduction firing step, an oxidation firing step of oxidizing and firing the impregnated body in an oxidizing gas atmosphere may be provided.
As an oxidizing gas in the oxidizing and baking step, oxygen or the like can be used, and a gas diluted with an inert gas may be used. Also, air may be used as the oxidizing gas.
The temperature of oxidative firing is preferably 400 to 600°C, more preferably 450 to 550°C, and preferably 500°C.
The oxidizing firing time may be 1 to 3 hours, or may be 1 to 2 hours.

<<Method for Producing Propylene>>
The method for producing propylene of the present embodiment is a method for producing propylene by subjecting the oxidative dehydrogenation catalyst of the present invention to contact treatment with a raw material gas containing propane and carbon dioxide, and subjecting propane to an oxidative dehydrogenation reaction.

The propylene production method can be carried out, for example, by filling a reactor with the above-mentioned oxidative dehydrogenation catalyst and circulating a raw material gas containing propane and carbon dioxide. The reaction system is not particularly limited as long as the effect of the present invention can be obtained.

The propylene production method may be a one-stage propylene production method in which the above-mentioned oxidative dehydrogenation catalyst is charged in a single reactor, or a multistage continuous propylene production method in which a plurality of reactors are charged. It's okay. In the case of a multi-stage continuous system, propylene may be produced in a part of the reactors, and the oxidative dehydrogenation catalyst described later may be regenerated in the remaining reactors.

The content of propane with respect to 100% by volume of the source gas is preferably 5 to 50% by volume, more preferably 20 to 30% by volume.

The carbon dioxide content is preferably 5 to 50% by volume, more preferably 20 to 30% by volume, with respect to 100% by volume of the source gas.

The raw material gas may contain gases other than propane and carbon dioxide, and examples of gases other than propane and carbon dioxide include inert gases such as helium and nitrogen.

The molar ratio of carbon dioxide to propane in the source gas (CO ₂ /C ₃ H ₈ ) is preferably 0.5 to 2, more preferably 0.75 to 1.25, and 1 is more preferred. When the above-described conventional oxidative dehydrogenation catalyst is used, the carbon dioxide conversion rate is low, and propylene cannot be efficiently produced unless the CO ₂ /C ₃ H ₈ ratio is set high. On the other hand, since the oxidative dehydrogenation catalyst of the present embodiment has a high carbon dioxide activation ability and a high carbon dioxide conversion rate, propylene is efficiently produced even at a low CO ₂ /CH ₃ H ₈ as described above. It is possible to

The reaction temperature is preferably 500-600°C, more preferably 550-600°C. When the reaction temperature is at least the lower limit of the above range, the equilibrium conversion rate increases. When the reaction temperature is equal to or lower than the upper limit of the above range, sintering of the active ingredient is suppressed, and a decrease in activity is suppressed.

The reaction pressure is preferably 0.05 to 0.1 MPa, more preferably 0.08 to 0.1 MPa, even more preferably 0.09 to 0.1 MPa. When the reaction pressure is equal to or higher than the lower limit of the above range, the conversion rate of carbon dioxide increases. When the reaction pressure is equal to or lower than the upper limit of the above range, the propane conversion rate does not decrease.

The Weight Hourly Space Velocity of propane in the raw material gas relative to the oxidative dehydrogenation catalyst is more preferably 3000 to 5000 hr ^-1 , still more preferably 3500 to 4000 hr ^-1 .

Examples of propane in the raw material gas supplied to the propylene production method of the present embodiment include shale gas-derived propane, naphtha-derived propane, biomass-derived propane, and the like.

In the method for producing propylene of the present embodiment, coke may accumulate on the oxidative dehydrogenation catalyst, resulting in a decrease in catalytic activity. A catalyst whose activity has decreased can be regenerated by contacting a regeneration gas containing an oxidizing gas.

The oxidizing gas includes oxygen, carbon dioxide, and the like. When the oxidizing gas is oxygen, air can be used as the regeneration gas.
The content of the oxidizing gas with respect to 100% by volume of the regeneration gas is preferably 20 to 100% by volume, more preferably 50 to 100% by volume.

The gas hourly space velocity (GHSV) of the oxidizing gas in the regeneration gas with respect to the oxidative dehydrogenation catalyst is more preferably 6000 to 10000 hr ^-1 , more preferably 7000 to 8000 hr ^-1 . preferable.

The regeneration temperature is preferably 400 to 600°C, more preferably 450 to 550°C. When the regeneration temperature is equal to or higher than the lower limit of the above range, combustion of coke is promoted. When the reaction temperature is equal to or lower than the upper limit of the above range, sintering of the active ingredient is suppressed, and a decrease in activity is suppressed.

The regeneration time can be appropriately adjusted according to the type of oxidizing gas, GHSV, regeneration temperature, and regeneration pressure. The playback time may be 1-2 hours, 1-3 hours, or 1-5 hours.

Since the oxidative dehydrogenation catalyst of the present embodiment contains a ceria carrier, it has a high coke combustion ability. Therefore, even if carbon dioxide is used as the oxidizing gas, the catalytic activity is sufficiently recovered. That is, by stopping the supply of propane from the raw material gas in the method for producing propylene, the catalyst can be regenerated, and propylene can be produced efficiently.

In the present embodiment, it is preferable to carry out a reduction treatment in which the regenerated catalyst is brought into contact with a reduction treatment gas containing a reducing gas. By performing the reduction treatment, if the active component is partially oxidized by the regeneration treatment, it can be converted again into an alloy or metal.

Hydrogen, carbon monoxide, etc. are mentioned as a reducing gas.
The content of the reducing gas with respect to 100% by volume of the reducing gas is preferably 20 to 100% by volume, more preferably 30 to 50% by volume.

The gas hourly space velocity (GHSV) of the reducing gas in the reducing gas with respect to the oxidative dehydrogenation catalyst is more preferably 6000 to 10000 hr ^-1 , more preferably 7000 to 8000 hr ^-1 . More preferred.

The reduction treatment temperature is preferably 400 to 600°C, more preferably 450 to 550°C.

The reduction treatment time can be appropriately adjusted according to the type of reducing gas, GHSV, regeneration temperature, and regeneration pressure. The reduction treatment time may be 0.5 to 1 hour, 0.5 to 1.5 hours, or 0.5 to 2 hours.

By using the oxidative dehydrogenation catalyst of the present invention, propylene can be produced efficiently over a longer period of time. Also, carbon dioxide can be effectively used.

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples below, but the present invention is not limited to the following examples.

<Characterization of oxidative dehydrogenation catalyst>
For the characterization of the oxidative dehydrogenation catalyst, transmission electron microscope observation and CO adsorption were performed.

(Transmission electron microscope observation)
The particle size of the oxidative dehydrogenation catalyst of each example was measured at an acceleration voltage of 200 kV using a transmission electron microscope (JOEL JEM-ARM200M) equipped with an energy dispersive X-ray (EDX) analyzer. After the oxidative dehydrogenation catalyst of each example was subjected to ultrasonic treatment with ethanol, it was dispersed on a Mo grid supported by a carbon membrane and observed. For the particle size distribution, the longest diameters of 126 particles randomly selected from 10 images were observed, and the average of these was taken as the average particle diameter.

(CO adsorption)
The degree of dispersion of platinum and cobalt in the oxidative dehydrogenation catalyst of each example was measured by CO adsorption measurement of the oxidative dehydrogenation catalyst. The degree of dispersion is the ratio of platinum and cobalt exposed on the surface to the total amount of platinum and cobalt contained in the oxidative dehydrogenation catalyst. A mixed gas containing 5% by volume of hydrogen and 95% by volume of air is passed through 40 mg of the oxidative dehydrogenation catalyst at 30 NmL/min for pretreatment at 550° C. for 30 minutes, followed by liquid nitrogen while purging helium. cooled. Next, a mixed gas containing 10% by volume of carbon monoxide and 90% by volume of helium was introduced by a pulse method. The mixed gas was introduced until it disappeared. Based on the amount of carbon monoxide adsorbed on the oxidative dehydrogenation catalyst, the distribution of platinum and cobalt is based on the premise that 1 molecule of carbon monoxide is adsorbed to 1 atom of platinum and 1 molecule of carbon monoxide is adsorbed to 1 atom of cobalt. calculated the degree.

<Oxidative dehydrogenation reaction of propane>
0.10 g of the oxidative dehydrogenation catalyst of each example was diluted with 0.90 g of sea sand (manufactured by Miyazaki Chemicals Co., Ltd.) and filled into a quartz cylindrical fixed-bed reaction tube with a diameter of 6 mm and a length of 20 cm. to form a catalyst layer. Next, the temperature of the catalyst layer was heated to 550° C., hydrogen was passed through at 10 NmL/min, and pretreatment was performed for 30 minutes. Then, instead of hydrogen, a source gas containing propane and carbon dioxide was passed through the catalyst layer at 20 NmL/min to carry out an oxidative dehydrogenation reaction of propane. The contents of propane, carbon dioxide, and helium are 25% by volume, 25% by volume, and 50% by volume, respectively, with respect to 100% by volume of the source gas.

The gas flowing out from the reactor outlet was analyzed by an online thermal conductivity detection gas chromatograph (Shimadzu Corporation, product name "GC-8A"). Propylene, propane, ethylene, ethane, methane, carbon monoxide, carbon dioxide, water, and hydrogen were detected in the reactor outlet gas.

The conversion rate of propane (X _C3H8 ) was calculated by Equation 3 below.

前記式３中、Ｆ^ｉｎ _Ｃ３Ｈ８は、反応器に流入したプロパンの流量（ｍｏｌ／ｍｉｎ）を示し、Ｆ^ｏｕｔ _Ｃ３Ｈ８は反応器から排出されたプロパンの流量（ｍｏｌ／ｍｉｎ）を示す。

In Equation 3, F ⁱⁿ _C3H8 represents the flow rate (mol/min) of propane introduced into the reactor, and F ^out _C3H8 represents the flow rate (mol/min) of propane discharged from the reactor.

The conversion rate of carbon dioxide (X _CO2 ) was calculated by Equation 4 below.

前記式４中、Ｆ^ｉｎ _ＣＯ２は、反応器に流入した二酸化炭素の流量（ｍｏｌ／ｍｉｎ）を示し、Ｆ^ｏｕｔ _ＣＯ２は反応器から排出された二酸化炭素の流量（ｍｏｌ／ｍｉｎ）を示す。

In Equation 4, F ⁱⁿ _CO2 represents the flow rate (mol/min) of carbon dioxide flowing into the reactor, and F ^out _CO2 represents the flow rate (mol/min) of carbon dioxide discharged from the reactor.

Propylene selectivity was calculated by the following equation 5.

前記式５中、Ｆ^ｏｕｔ _Ｃ３Ｈ６は、反応器から排出されたプロピレンの流量（ｍｏｌ／ｍｉｎ）を示し、Ｆ^ｏｕｔ _Ｃ２Ｈ６は、反応器から排出されたエタンの流量（ｍｏｌ／ｍｉｎ）を示し、Ｆ^ｏｕｔ _Ｃ２Ｈ４は、反応器から排出されたエチレンの流量（ｍｏｌ／ｍｉｎ）を示し、Ｆ^ｏｕｔ _ＣＨ４は、反応器から排出されたメタンの流量（ｍｏｌ／ｍｉｎ）を示す。

In Equation 5, F ^out _C3H6 represents the flow rate (mol/min) of propylene discharged from the reactor, F ^out _C2H6 represents the flow rate (mol/min) of ethane discharged from the reactor, and F ^Out _C2H4 indicates the flow rate (mol/min) of ethylene discharged from the reactor, and F ^out _CH4 indicates the flow rate (mol/min) of methane discharged from the reactor.

Propylene yield was calculated by propane conversion×propylene selectivity/100.

<Measurement of carbon content of oxidative dehydrogenation catalyst after reaction>
The amount of carbon after the reaction of the oxidative dehydrogenation catalyst of each example was measured by BELCAT II manufactured by MicrotracBEL. Helium was passed through the oxidative dehydrogenation catalyst (including sea sand) after reacting for 10 hours at 30 NmL/min, pretreatment was performed at 150° C. for 30 minutes, and then the temperature was lowered to room temperature. Next, while a mixed gas containing 50% by volume of oxygen and 50% by volume of helium was circulated at 40 NmL/min, it was heated to 40 to 900° C. at a temperature increase rate of 5° C./min. The amount of carbon dioxide in the outlet gas was quantified by an on-line mass meter.

[Example 1]
Ceria (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., reference catalyst “JRC-CEO”, specific surface area 123.1 m ² /g), H ₂ PtCl ₆ as a Pt source, and In(NO ₃ ) ₃ 3H as an In source An impregnation solution prepared by dissolving Co(NO ₃ ) ₂ 6H ₂ O as a ₂ O, 3d metal source in ion-exchanged water so as to have the composition of catalyst A shown in Table 1 was impregnated by evaporation to dryness. , and dried under reduced pressure at 50° C. to obtain an impregnated body. The impregnated body was calcined at 500° C. for 1 hour in an air stream, and then reduced and calcined at 600° C. for 1 hour in a hydrogen stream to obtain a catalyst A in which a Pt—In—Co alloy was supported on ceria. Table 1 shows the composition of catalyst A, the average particle size, the degree of dispersion of platinum and cobalt, and the amount of carbon after the reaction.

[Comparative Example 1]
Except that In(NO ₃ ) _{3.3H 2} O and Co(NO ₃ ) 2.6H ₂ O were not added and the composition of the impregnation liquid was changed so that the composition of catalyst B _shown in Table 1 was obtained, Catalyst B in which Pt metal was supported on ceria was obtained in the same manner as in Example 1. Table 1 shows the results of the composition, average particle size, degree of dispersion of platinum, and amount of carbon after the reaction of catalyst B.

[Comparative Example 2]
Ceria _{was added with} Pt- A catalyst C supporting a Co alloy was obtained. Table 1 shows the composition of catalyst C, the average particle size, the degree of dispersion of platinum and cobalt, and the amount of carbon after the reaction.

[Comparative Example 3]
Ceria _{was added with} Pt- A catalyst D supporting an In alloy was obtained. Table 1 shows the composition, average particle size, degree of dispersion of platinum, and amount of carbon after the reaction of Catalyst D.

Without adding In(NO ₃ ) _{3.3H 2} O and Co(NO ₃ ) _{2.6H 2} O, SnCl ₂ was added as a Sn source, and the impregnating solution was prepared so as to have the composition of catalyst E shown in Table 1. A catalyst E in which a Pt—Sn alloy was supported on ceria was obtained in the same manner as in Example 1, except that the composition of was changed. The composition of Catalyst E is shown in Table 1.

Using the catalysts of Example 1 and Comparative Examples 1 to 4, oxidative dehydrogenation of propane was carried out. The results are shown in FIGS.

[Example 2]
Ni(NO ₃ ) 2.6H ₂ O was added instead of Co(NO ₃ ) _{2.6H 2} O as the 3d metal source, and the composition of the impregnation liquid was changed so that the composition of catalyst F shown in Table 1 was _obtained . A catalyst F in which a Pt--In--Ni alloy was supported on ceria was obtained in the same manner as in Example 1, except for the above. The composition of Catalyst F is shown in Table 1.
Using the catalyst of Example 2, oxidative dehydrogenation of propane was carried out. The results are shown in FIG.

[Example 3]
Co(NO _{3 )} 2.6H ₂ O and Ni(NO ₃ ) 2.6H ₂ O were added as 3d metal sources, and the composition of the impregnation liquid was changed so as to obtain the composition of catalyst G shown in Table 1 _. obtained a catalyst G in which a Pt--In--Co--Ni alloy was supported on ceria in the same manner as in Example 1. The composition of Catalyst G is shown in Table 1.
Using the catalyst of Example 3, oxidative dehydrogenation of propane was carried out. The results are shown in FIG.

[Comparative Example 5]
A catalyst H in which a Pt--In--Co alloy was supported on alumina was obtained in the same manner as in Example 1, except that alumina was used as the carrier instead of ceria. The composition of Catalyst H is shown in Table 1.

[Comparative Example 6]
A catalyst I in which a Pt--In--Co alloy was supported on zirconia was obtained in the same manner as in Example 1, except that zirconia was used as the support instead of ceria. The composition of Catalyst I is shown in Table 1.

[Comparative Example 7]
A catalyst J in which a Pt--In--Co alloy was supported on titania was obtained in the same manner as in Example 1, except that titania was used instead of ceria as the carrier. The composition of Catalyst J is shown in Table 1.

Oxidative dehydrogenation of propane was carried out using the catalysts of Comparative Examples 5-7. The results are shown in FIG. For comparison, the reaction results of the catalyst of Example 1 are also shown.

[Example 1-1]
Using the catalyst A of Example 1, a catalyst life test was conducted. The reaction was carried out for about 30 hours by the method described in <Oxidative Dehydrogenation of Propane> above. After that, while maintaining the temperature of the catalyst layer at 550° C., instead of the source gas, a regeneration gas containing carbon dioxide is passed at 25 NmL/min (a mixed gas of carbon dioxide: 5 NmL/min and helium: 20 NmL/min). Regeneration treatment was performed for 5 hours. After the regeneration treatment, while the temperature of the catalyst layer was maintained at 550° C., instead of the regeneration gas, a reduction treatment gas containing hydrogen was passed at 30 NmL/min (a mixed gas of hydrogen: 10 NmL/min and helium: 20 NmL/min). Then, a reduction treatment was performed for 30 minutes. After the reduction treatment, while maintaining the temperature of the catalyst layer at 550° C., the raw material gas was again circulated instead of the reduction treatment gas to restart the reaction (2nd cycle in FIG. 8). Then, after the reaction was carried out for about 30 hours, the regeneration treatment and reduction treatment described above were carried out again, and then the reaction was restarted (3rd cycle in FIG. 8).

As shown in FIG. 3, Catalyst A of Example 1 had high propane conversion and propylene selectivity, and almost no decrease in these over time was confirmed. In addition, as shown in FIG. 4, the catalyst A of Example 1 was less likely to decrease the conversion rate of carbon dioxide over time than the catalysts B to E of Comparative Examples 1 to 4. Moreover, as shown in FIGS. 5 and 6, it was found that the same effect can be obtained when nickel is used as the 3d transition metal element.

In addition, as shown in FIG. 7, in the catalysts H to J of Comparative Examples 5 to 7 using a carrier other than ceria, the propane conversion rate and the carbon dioxide conversion rate were low in the initial stage, and these decreased with time. significantly confirmed.

Further, as shown in FIG. 8, in the life test using catalyst A of Example 1, it is possible to use carbon dioxide as the oxidizing gas, and by performing regeneration treatment twice, high propane It was possible to continue the reaction while maintaining the conversion rate and carbon dioxide conversion rate.

The oxidative dehydrogenation catalyst according to the present invention is useful because pyropyrene can be efficiently produced over a long period of time.

Claims (4)

An oxidative dehydrogenation catalyst for producing propylene by an oxidative dehydrogenation reaction of propane, wherein the oxidative dehydrogenation reaction is performed by reacting propane with carbon dioxide, and the oxidative dehydrogenation catalyst contains an active component is supported on a ceria carrier, and the oxidative dehydrogenation catalyst contains a platinum element, an indium element, and a 3d transition metal element as the active components. 2. The oxidative dehydrogenation catalyst according to claim 1, wherein said 3d transition metal element is one or more elements selected from the group consisting of cobalt element and nickel element. 3. The oxidative dehydrogenation catalyst according to claim 1, wherein said 3d transition metal element is a cobalt element. 4. The oxidative dehydrogenation catalyst according to claim 1, wherein said platinum element, said indium element, and said 3d transition metal element form an alloy.

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