Dehydrogenation catalyst, method for producing dehydrogenation catalyst, and method for producing propylene

Abstract

The present invention pertains to a dehydrogenation catalyst for producing propylene by a dehydrogenation reaction of propane, said catalyst comprising MFI type zeolite, elemental platinum, and elemental M, wherein: the molar ratio (Si / Al) of silicon to elemental aluminum of the MFI type zeolite is 50 or more; the elemental M is at least one element selected from the group consisting of elemental germanium, elemental copper, elemental indium, elemental iron, elemental ruthenium, and elemental rhenium; and the elemental platinum and the elemental M are located in a channel of the MFI type zeolite.

Description

Dehydrogenation catalyst, method for producing dehydrogenation catalyst, and method for producing propylene

[0001] The present invention relates to a dehydrogenation catalyst, a method for producing a dehydrogenation catalyst, and a method for producing propylene. This application claims priority based on Japanese Patent Application No. 2023-151834, filed on September 20, 2023, the contents of which are incorporated herein by reference.

[0002] Propylene is a key chemical used to manufacture a variety of chemicals, including resins, surfactants, dyes, and pharmaceuticals. In recent years, the supply of propylene has been declining due to a shift in the feedstock for steam crackers from naphtha derived from crude oil to ethane derived from shale gas.

[0003] Given this background, the production of propylene by the dehydrogenation of propane has attracted attention. Because the dehydrogenation of propane is an endothermic reaction, high temperatures of 600°C or higher are required for the reaction to proceed. Extensive research has been conducted on catalysts for the dehydrogenation of propane, and catalysts containing platinum metal are known. However, when the dehydrogenation of propane is carried out at temperatures above 600°C using conventional catalysts containing platinum metal, the activity decreases due to coke deposition and / or sintering.

[0004] Non-Patent Document 1 discloses a catalyst containing a platinum-based alloy. It is disclosed that the use of a catalyst containing a platinum-based alloy suppresses the decrease in activity in the dehydrogenation reaction of propane at 600°C or higher compared to conventional catalysts containing platinum metal.

[0005] J. Feng et al., Chin. J. Chem. Eng., 2014, 22, 1232.

[0006] However, the catalyst life of the propane dehydrogenation catalyst described in Non-Patent Document 1 is insufficient. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dehydrogenation catalyst for producing propylene by the dehydrogenation reaction of propane, which has a longer life than conventional catalysts, a method for producing the dehydrogenation catalyst, and a method for producing propylene using the dehydrogenation catalyst.

[0007] In order to solve the above problems, the present invention has the following aspects. [1] A dehydrogenation catalyst for producing propylene by dehydrogenation of propane, comprising an MFI zeolite, platinum, and an M element, wherein the MFI zeolite has a silicon to aluminum molar ratio (Si / Al) of 50 or more, the M element is one or more elements selected from the group consisting of germanium, copper, indium, iron, ruthenium, and rhenium, and the platinum and M element are located within the channels of the MFI zeolite. [2] The dehydrogenation catalyst according to [1], wherein the platinum and M element form alloy clusters. [3] The dehydrogenation catalyst according to [1] or [2], further comprising manganese oxide or tin oxide, wherein the manganese oxide or tin oxide is located within the channels of the MFI zeolite. [4] The dehydrogenation catalyst according to any one of [1] to [3], wherein the MFI zeolite does not contain aluminum. [5] The dehydrogenation catalyst according to any one of [1] to [4], wherein the M element is germanium. [6] A method for producing the dehydrogenation catalyst according to any one of [1] to [5], comprising: a hydrothermal synthesis step of hydrothermally synthesizing a mixed solution containing a structure-directing agent, a compound containing platinum, the compound containing M, and a compound containing silicon; an oxidation-calcination step of oxidizing and calcining the solid obtained in the hydrothermal synthesis step in an oxidizing gas atmosphere to remove the structure-directing agent; and a reduction-calcination step of reducing and calcining the calcined body obtained in the oxidation-calcination step in a reducing gas atmosphere. [7] A method for producing propylene, comprising contacting a feed gas containing propane with the dehydrogenation catalyst according to any one of [1] to [5]. [8] A method for producing propylene according to [7], wherein the reaction temperature is 550 to 650°C.

[0008] According to the present invention, it is possible to provide a dehydrogenation catalyst for producing propylene by the dehydrogenation of propane, which has a longer life than conventional catalysts, a method for producing the dehydrogenation catalyst, and a method for producing propylene using the dehydrogenation catalyst.

[0009] FIG. 1 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Examples 1 and 2 and Comparative Examples 1 and 2. FIG. 2 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Example 4 and Comparative Examples 2 to 4. FIG. 3 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Example 5 and Comparative Examples 2 and 5. FIG. 4 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Examples 6 to 8 and Comparative Example 2. FIG. 5 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Comparative Examples 2 and 6 to 8. FIG. 6 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Comparative Examples 2 and 9 to 11. FIG. 7 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Examples 1, 2, 9, and 10. FIG. 8 is a graph showing the results of propane dehydrogenation reactions using the catalysts of Examples 2, 3, 11, and 12.

[0010] The following describes in detail the embodiments of the present invention. However, the following description is an example of an embodiment of the present invention, and the present invention is not limited to these contents and can be modified and implemented within the scope of its gist.

[0011] <Dehydrogenation Catalyst> The dehydrogenation catalyst of this embodiment is a dehydrogenation catalyst for producing propylene by the dehydrogenation reaction of propane. The dehydrogenation catalyst includes MFI zeolite, platinum element, and M element. The molar ratio of silicon to aluminum element (Si / Al) of the MFI zeolite is 50 or more. The M element is one or more elements selected from the group consisting of germanium element, copper element, indium element, iron element, ruthenium element, and rhenium element. The platinum element and the M element are located within the channels of the MFI zeolite. The platinum element and the M element are active components in the dehydrogenation reaction of propane.

[0012] <MFI Zeolite> MFI zeolite is a zeolite having three-dimensional pores formed by the intersection of linear channels of 10-membered rings and sinusoidal channels of 10-membered rings. Examples of MFI zeolite include ZSM-5 containing aluminum element and silicalite not containing aluminum element.

[0013] The molar ratio of silicon to aluminum element (Si / Al) of MFI zeolite is at least 50, preferably at least 100, and more preferably at least 300, and silicalite that does not contain aluminum element is particularly preferred. When Si / Al is at least the above-mentioned lower limit, the number of acid sites in the MFI zeolite decreases, and coke formation is suppressed, resulting in less deterioration of catalytic activity.

[0014] MFI zeolite has 10-membered ring linear channels and 10-membered ring sinusoidal channels within its crystallites, which are micropores with a pore diameter of less than 2 nm. It is preferable that MFI zeolite is substantially free of mesopores with a pore diameter of 2 to 50 nm. "MFI zeolite is substantially free of mesopores" means that the ratio of the mesopore volume to the total pore volume is 10% by volume or less. The ratio of the mesopore volume to the total pore volume is preferably 5% by volume or less, more preferably 0% by volume. In this specification, "total pore volume" and "mesopore volume" can be determined from the pore distribution obtained by mercury intrusion porosimetry. Mercury intrusion porosimetry is a measurement method based on the law of capillary action. This law can be expressed, for example, by the following formula: In the formula, D is the pore diameter, P is the pressure, γ is the surface tension, and θ is the contact angle. In other words, the pore diameter D is determined from the applied pressure P. The total pore volume can be calculated by integrating the obtained pore distribution. The pore volume of mesopores can also be calculated by integrating the pores in the pore distribution over the range of 2 to 50 nm.

[0015] The BET specific surface area of ​​MFI zeolite is 250 to 700 m ２ / g, and 300 to 600m ２ / g, and more preferably 350 to 550m ２ / g. In this specification, the "BET specific surface area" can be measured by a nitrogen adsorption method.

[0016] <Active Component> The dehydrogenation catalyst contains platinum and an M element as active components. The M element is one or more elements selected from the group consisting of germanium, copper, indium, iron, ruthenium, and rhenium, preferably one or more elements selected from the group consisting of germanium, indium, and ruthenium, and more preferably germanium. The M element may be one type or two or more types.

[0017] The molar ratio of M element to platinum element (M / Pt) is preferably 0.3 to 7.0, more preferably 0.5 to 5.0, and even more preferably 1.0 to 4.5. When M / Pt is equal to or greater than the lower limit of the above range, the catalytic activity, propylene selectivity, and catalyst durability are improved. When M / Pt is equal to or less than the upper limit of the above range, the propylene selectivity and catalyst durability are improved.

[0018] The platinum element and the M element are located within the channels of the MFI zeolite. The platinum element and the M element are preferably located within the sinusoidal channels of the 10-membered ring. The location of the platinum element and the M element within the sinusoidal channels of the 10-membered ring can be confirmed by combining high-angle annular dark-field scanning transmission microscopy (HAADF-STEM) observation combined with energy-dispersive X-ray (EDX) and integrated differential phase contrast (iDPC) STEM observation. Because iDPC has high sensitivity to light elements (silicon, oxygen, etc.), it can observe the zeolite framework. On the other hand, because HAADF-STEM has high sensitivity to heavy elements (platinum, etc.), it can observe the platinum element and the M element. That is, by comparing the iDPC-STEM image with the HAADF-STEM image, the locations of the platinum element and the M element within the MFI zeolite can be confirmed. It is sufficient that at least a portion of the platinum element (the M element) is located within the channels of the MFI zeolite. The amount of platinum element (M element) located in the channel of MFI zeolite is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 100 mol% relative to the total amount of platinum element (M element).

[0019] Platinum element and M element are located within the channels of MFI zeolite, thereby suppressing sintering of platinum and M.

[0020] The platinum element and the M element may be in the form of simple metal, oxide, or an alloy of platinum and the M element. In particular, the platinum element and the M element preferably form an alloy cluster. In this specification, "cluster" refers to particles having a particle diameter of 1.2 nm or less. The average particle diameter of the alloy clusters is preferably 1.0 nm or less, more preferably 0.9 nm or less, and even more preferably 0.8 nm or less. The particle diameter of the alloy clusters can be measured by HAADF-STEM observation combined with energy dispersive X-ray (EDX) analysis. The longest diameters of 100 or more randomly selected alloy clusters can be measured, and the average of these can be used as the average particle diameter. The number of alloy clusters in the sample may be 100.

[0021] The platinum and M elements form alloy clusters, which increases the amount of platinum present on the surface of the alloy clusters compared to larger particles, leading to more efficient platinum utilization. It is also believed that the catalytic activity is improved by the geometric and electronic effects specific to cluster alloys.

[0022] <Manganese oxide, tin oxide> The dehydrogenation catalyst preferably contains manganese oxide or tin oxide. It may contain both manganese oxide and tin oxide. Of these, it is preferable to contain manganese oxide. The manganese oxide or tin oxide is preferably located within the channels of the MFI zeolite. It is more preferable that the manganese oxide or tin oxide is located within the sinusoidal channels of the 10-membered ring. The location of the manganese oxide or tin oxide within the sinusoidal channels of the 10-membered ring can be confirmed in the same manner as in the case of the platinum element and the M element described above. It is sufficient that at least a portion of the manganese oxide (tin oxide) is located within the channels of the MFI zeolite. The amount of manganese oxide (tin oxide) located within the channels of the MFI zeolite is preferably 50 mol % or more, more preferably 70 mol % or more, still more preferably 90 mol % or more, and particularly preferably 100 mol %, relative to the total amount of manganese oxide (tin oxide).

[0023] When propylene is produced by the dehydrogenation of propane, hydrogen is produced as a by-product. It is believed that this hydrogen adsorbs onto the surface of the metal (alloy) of platinum element and / or M element, which is the active component, poisoning the active component. The present inventors have discovered for the first time that by including manganese oxide or tin oxide in the dehydrogenation catalyst and positioning the manganese oxide or tin oxide in the vicinity of the active component, the manganese oxide or tin oxide adsorbs hydride during propylene production and then desorbs it as hydrogen (i.e., hydrogen is produced in the manganese oxide or tin oxide, not in the active component), thereby preventing poisoning of the active component. Furthermore, the inclusion of manganese oxide or tin oxide also prevents coking of the dehydrogenation catalyst.

[0024] <Composition> The combined content of platinum and M element relative to the total mass of the dehydrogenation catalyst is preferably 0.1 to 1.6 mass%, more preferably 0.3 to 1.4 mass%, and even more preferably 0.4 to 1.2 mass%. When the combined content of platinum and M element is equal to or greater than the lower limit of the above range, the activity per catalyst mass is improved. When the combined content of platinum and M element is equal to or less than the upper limit of the above range, alloy clusters can be appropriately formed.

[0025] The content of platinum element relative to the total mass of the dehydrogenation catalyst is preferably 0.05 to 1.0 mass%, more preferably 0.1 to 0.8 mass%, and even more preferably 0.2 to 0.6 mass%. When the content of platinum element is equal to or greater than the lower limit of the above range, the activity per catalyst mass is improved. When the content of platinum element is equal to or less than the upper limit of the above range, alloy clusters can be appropriately formed.

[0026] The content of the M element relative to the total mass of the dehydrogenation catalyst is preferably 0.05 to 0.6 mass%, more preferably 0.1 to 0.5 mass%, and even more preferably 0.2 to 0.4 mass%. When the content of the M element is equal to or greater than the lower limit of the above range, the catalytic activity, propylene selectivity, and catalyst durability are improved. When the content of the M element is equal to or less than the upper limit of the above range, the propylene selectivity and catalyst durability are improved.

[0027] The content of MFI zeolite relative to the total mass of the dehydrogenation catalyst is preferably 96 to 99.5 mass%, more preferably 97 to 99 mass%, and even more preferably 97.5 to 98.8 mass%. When the content of MFI zeolite is at least the lower limit of the above range, the catalytic activity per Pt mass is improved. When the content of MFI zeolite is at most the upper limit of the above range, the catalytic activity is improved.

[0028] When the dehydrogenation catalyst contains manganese oxide or tin oxide, the total content of elemental manganese and tin is preferably 0.05 to 2.0 mass%, more preferably 0.1 to 1.5 mass%, and even more preferably 0.2 to 1.0 mass%. When the total content of elemental manganese and tin is equal to or greater than the lower limit of the above range, the catalytic activity, propylene selectivity, and catalyst durability are improved. When the total content of elemental manganese and tin is equal to or less than the upper limit of the above range, the catalytic activity, propylene selectivity, and catalyst durability are improved.

[0029] When the dehydrogenation catalyst contains manganese oxide or tin oxide, the molar ratio of the total of elemental manganese and elemental tin to the total of elemental platinum and element M ((Mn+Sn) / (Pt+M)) is preferably 0.1 to 1.0, more preferably 0.2 to 0.9, and even more preferably 0.3 to 0.7.

[0030] When the dehydrogenation catalyst contains manganese oxide or tin oxide, the molar ratio of the sum of elemental manganese and elemental tin to elemental platinum ((Mn+Sn) / Pt) is preferably 0.2 to 3, more preferably 0.4 to 2, and even more preferably 0.6 to 1.5. When (Mn+Sn) / Pt is at least the lower limit of the above range, the catalytic activity, propylene selectivity, and catalyst durability are improved. When (Mn+Sn) / Pt is at most the upper limit of the above range, the catalytic activity and propylene selectivity are improved.

[0031] When the dehydrogenation catalyst contains manganese oxide or tin oxide, the molar ratio of the sum of elemental manganese and elemental tin to element M ((Mn+Sn) / M) is preferably 0.1 to 2, more preferably 0.3 to 1.6, and even more preferably 0.5 to 1.5.

[0032] The dehydrogenation catalyst may contain other components in addition to MFI zeolite, platinum element, M element, manganese oxide, and tin oxide. Examples of other components include metal elements other than platinum element and M element, and alkali metals derived from the production process of MFI zeolite. Preferred alkali metals are K and Na. When the dehydrogenation catalyst contains other components, the content of the other components relative to the total mass of the dehydrogenation catalyst is preferably 0.3 to 1.5 mass%, more preferably 0.4 to 1.1 mass%, and even more preferably 0.5 to 0.8 mass%. When the dehydrogenation catalyst contains an alkali metal, alloy clusters of platinum element and M element are more likely to be formed.

[0033] In this specification, the contents of "platinum element, M element, manganese element, tin element, etc." can be measured by inductively coupled plasma atomic emission spectrometry (ICP). For example, after dissolving the dehydrogenation catalyst in acid, the amount of each element can be measured using an inductively coupled plasma atomic emission spectrometry device.

[0034] <Physical properties>

[0035] The BET specific surface area of ​​the dehydrogenation catalyst is 250 to 700 m ２ / g, and 300 to 600m ２ / g, and more preferably 350 to 550m ２ It is more preferable that the SiO2 content is 1 / g.

[0036] The dehydrogenation catalyst preferably has substantially no mesopores with a pore diameter of 2 to 50 nm. "The dehydrogenation catalyst has substantially no mesopores" means that the ratio of the mesopore volume to the total pore volume is 10% by volume or less. The ratio of the mesopore volume to the total pore volume is more preferably 5% by volume or less, and even more preferably 0% by volume.

[0037] <<Method for Producing Dehydrogenation Catalyst>> The method for producing a dehydrogenation catalyst of this embodiment includes a hydrothermal synthesis step of hydrothermally synthesizing a mixed solution containing a structure-directing agent, a compound containing platinum, a compound containing M, a compound containing silicon, and, if necessary, a compound containing aluminum; an oxidation-calcination step of oxidizing and calcining the solid obtained in the hydrothermal synthesis step in an oxidizing gas atmosphere to remove the structure-directing agent; and a reduction-calcination step of reducing and calcining the calcined body obtained in the oxidation-calcination step in a reducing gas atmosphere. When the dehydrogenation catalyst contains manganese oxide or tin oxide, the mixed solution may contain a compound containing manganese or a compound containing tin. The mixed solution can be produced by a mixed solution preparation step.

[0038] <Mixture Liquid Preparation Step> As the structure-directing agent used in the mixture liquid preparation step, tetrapropylammonium hydroxide (hereinafter also referred to as "TPAOH") or tetrapropylammonium bromide, which can generate tetrapropylammonium ions, can be used.

[0039] The compound containing platinum element, the compound containing M element, the compound containing manganese element, and the compound containing tin element are not particularly limited, and examples thereof include inorganic salts such as chlorides, sulfides, nitrates, carbonates, fluoride salts, ammonium salts, and ammonium fluoride salts; organic salts such as oxalates, acetylacetonate salts, dimethylglyoxime salts, and ethylenediamine acetate salts; chelate compounds; carbonyl compounds; cyclopentadienyl compounds; ammine complexes; alkoxide compounds; and alkyl compounds.

[0040] Examples of compounds containing silicon include water glass, colloidal silica, and alkoxide compounds, with alkoxide compounds being preferred, and tetraethoxysilane (hereinafter also referred to as "TEOS") being preferred. Examples of compounds containing aluminum include aluminates and alkoxide compounds.

[0041] In order to dissolve the silicon-containing compound and the aluminum-containing compound, the mixed solution preferably contains an acid or a base, and more preferably a base. When the mixed solution contains an acid or a base, if an alkoxide compound is used as the silicon-containing compound or the aluminum-containing compound, the alkoxide compound is hydrolyzed and dissolved in the mixed solution. The base is not particularly limited, but examples thereof include hydroxides of alkali metals, and sodium hydroxide and potassium hydroxide are preferred.

[0042] Examples of the solvent for the mixed solution include water, ethanol, and acetone, with water being preferred. It is also preferred to add a dispersant in addition to the above compounds. The dispersant is preferably a compound having a nitrogen atom, and more preferably ethylenediamine.

[0043] The order of addition of the structure-directing agent, the compound containing platinum element, the compound containing M element, the compound containing silicon element (and optionally the compound containing aluminum element), the compound containing manganese element, and the compound containing tin element is not particularly limited.

[0044] <Hydrothermal synthesis step> The temperature for the hydrothermal synthesis is preferably 150 to 200° C., more preferably 160 to 190° C., and even more preferably 170 to 180° C. The time for the hydrothermal synthesis is preferably 80 to 120 hours, more preferably 70 to 110 hours, and even more preferably 80 to 105 hours.

[0045] It is preferable to separate the solid obtained in the hydrothermal synthesis step and wash it. Examples of washing liquids include water, ethanol, acetone, etc. After washing, the solid may be dried.

[0046] <Oxidation and baking step> Examples of the oxidizing gas in the oxidation and baking step include oxygen and air, and a gas diluted with an inert gas may also be used. The temperature for oxidation and baking is preferably 500 to 700°C, more preferably 520 to 660°C, and more preferably 540 to 620°C. The time for oxidation and baking may be 5 to 20 hours, 7 to 15 hours, or 8 to 12 hours. The oxidation and baking may be carried out only once, or two or more times.

[0047] The structure-directing agent can be removed by the oxidizing and baking step. Furthermore, when the mixed liquid contains a compound containing elemental manganese or a compound containing elemental tin, the oxidizing and baking step produces manganese oxide or tin oxide.

[0048] <Reducing and Firing Step> Examples of reducing gases used in the reducing and firing step include hydrogen and carbon monoxide, and gas diluted with an inert gas may also be used. The temperature for reducing and firing is preferably 500 to 720°C, more preferably 550 to 710°C, and more preferably 600 to 700°C. The time for reducing and firing may be 0.2 to 10 hours, 0.5 to 7 hours, or 1 to 5 hours. It has been confirmed that when a compound containing manganese or a compound containing tin is used, manganese and tin do not form alloys with platinum even after reducing and firing. Platinum and manganese or tin are located within the channels of MFI zeolite, but platinum-manganese alloys and platinum-tin alloys are thought to be unable to form within the pores of MFI zeolite due to their large size. It is also thought that the oxidation numbers of manganese oxide and tin oxide decrease as a result of reducing and firing. For example, MnO ２ When reducing and firing, MnO ２ A part of ２ O ３ , Mn ３ O ４ The reduction firing may be carried out only once, or may be carried out two or more times.

[0049] The reduction and calcination step is preferably carried out by passing a reducing gas through the calcined body packed during the reaction. The gas hourly space velocity of the reducing gas relative to the calcined body is 2,500 to 75,000 hr －１ It is more preferable that:

[0050] <<Propylene Production Method>> The propylene production method of the present embodiment is a method for producing propylene by a dehydrogenation reaction of propane, which includes bringing a feed gas containing propane into contact with the dehydrogenation catalyst of the present invention.

[0051] The propylene production method can be carried out, for example, by filling a reactor with the above-mentioned dehydrogenation catalyst and passing a feed gas containing propane through it. The reaction system is not particularly limited as long as the effects of the present invention can be obtained, but examples include a fixed bed system, a fluidized bed system, and a moving bed system, with the fixed bed system being preferred.

[0052] The propylene production method may be a single-stage propylene production method in which the above-mentioned dehydrogenation catalyst is packed into a single reactor, or a multi-stage continuous propylene production method in which the dehydrogenation catalyst is packed into a plurality of reactors.

[0053] The content of propane relative to 100% by volume of the raw material gas is preferably 20 to 100% by volume, and more preferably 50 to 100% by volume. Examples of gases other than propane in the raw material gas include inert gases such as helium and nitrogen.

[0054] The feed gas may contain hydrogen. When the feed gas contains hydrogen, coke formation is suppressed. The hydrogen content relative to 100% by volume of the feed gas is preferably 10 to 40% by volume, and more preferably 10 to 20% by volume. When the hydrogen content is equal to or greater than the lower limit of the above range, the catalyst life is improved. When the hydrogen content is equal to or less than the upper limit of the above range, the catalytic activity is improved. The dehydrogenation catalyst of this embodiment is less likely to experience a decrease in catalytic activity, so the catalyst life can be extended even if the feed gas does not contain hydrogen.

[0055] The reaction temperature is preferably 550 to 650°C, more preferably 580 to 640°C, and even more preferably 600 to 630°C. When the reaction temperature is equal to or higher than the lower limit of the above range, the equilibrium conversion rate and reaction rate are improved. When the reaction temperature is equal to or lower than the upper limit of the above range, sintering of the active component is suppressed, and a decrease in catalytic activity is suppressed.

[0056] The reaction pressure is preferably 0.1 to 0.3 MPa, more preferably 0.1 to 0.25 MPa, and even more preferably 0.1 to 0.2 MPa. The reaction pressure may be atmospheric pressure.

[0057] The weight hourly space velocity (WHSV) of propane in the feed gas relative to the dehydrogenation catalyst is 1 to 10 hr －１ More preferably, it is 2 to 4 hours. －１ When the WHSV is at least the lower limit of the above range, productivity is improved.

[0058] Examples of propane in the raw material gas used in the propylene production method of this embodiment include propane derived from shale gas, propane derived from naphtha, and propane derived from biomass.

[0059] By using the dehydrogenation catalyst of the present invention, it becomes possible to produce propylene over a longer period of time.

[0060] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0061] <Characterization and Analysis of Dehydrogenation Catalyst> Characterization and analysis of the dehydrogenation catalyst were carried out by high-angle scattering annular dark-field scanning transmission microscope observation, composition analysis, and measurement of the carbon content of the dehydrogenation catalyst after the reaction.

[0062] (High-Angle Scattering Annular Dark-Field Scanning Transmission Microscope Observation) The particle size of the active component (alloy cluster) of each dehydrogenation catalyst was measured using a high-angle scattering annular dark-field scanning transmission microscope (FEI Titan G-2) equipped with an energy-dispersive X-ray (EDX) analyzer at an accelerating voltage of 300 kV. Integrated differential phase contrast (iDPC) was also performed using the high-angle scattering annular dark-field scanning transmission microscope to confirm the zeolite framework. Specifically, each dehydrogenation catalyst was crushed, ultrasonicated in ethanol, and dispersed on a Mo grid supported by a carbon film for observation. The particle size distribution was determined by observing the longest diameter of at least 100 randomly selected particles (alloy clusters, the active component) in 10 images, and averaging these values ​​to determine the average particle size.

[0063] (Composition Analysis) The composition of the dehydrogenation catalyst in each example was analyzed by inductively coupled plasma atomic emission spectrometry (ICP). The dehydrogenation catalyst was dissolved in a mixed solution of hydrofluoric acid, nitric acid, and hydrochloric acid, and the amount of each element was measured using an inductively coupled plasma atomic emission spectrometer.

[0064] <Measurement of Carbon Amount of Dehydrogenation Catalyst After Reaction> The carbon amount of the dehydrogenation catalyst of each example after reaction was measured using a BELCAT II manufactured by MicrotracBEL. Helium was passed through 50 mg of the dehydrogenation catalyst after 19.5 hours of reaction at 20 NmL / min, and the catalyst was pretreated at 150°C for 1 hour, after which the temperature was lowered to 100°C. Next, a mixed gas of 2 vol% oxygen and 98 vol% helium was passed through at 50 NmL / min, and the catalyst was heated from 100 to 700°C at a constant temperature increase rate. The amount of carbon dioxide in the outlet gas was quantified using an online mass meter. Note that [g] in Table 1 refers to the carbon amount per 1 g of catalyst.

[0065] <Propane dehydrogenation reaction> The dehydrogenation catalyst of each example was packed into a cylindrical quartz fixed-bed reactor tube with a diameter of 4 mm to form a catalyst layer. Hydrogen was then passed through the catalyst layer to perform pretreatment. Thereafter, a raw material gas containing propane was passed through the catalyst layer to perform the propane dehydrogenation reaction.

[0066] The gas discharged from the reactor was analyzed by an online thermal conductivity gas chromatograph (Shimadzu Corporation, product name "GC-8A") Propylene, propane, ethylene, ethane, and methane were detected in the gas at the reactor outlet.

[0067] The propane conversion was calculated according to the following formula 1.

[0068] In the formula 1, [C ３ H ８ ] ｉｎｌｅｔ indicates the flow rate (mol / min) of propane supplied to the reactor, [C ３ H ８ ] ｏｕｔｌｅｔ indicates the flow rate (mol / min) of propane discharged from the reactor.

[0069] The selectivity of propylene was calculated by the following formula 2.

[0070] In the formula 2, [C ３ H ６ ] indicates the flow rate (mol / min) of propylene discharged from the reactor, and [C ２ H ６] indicates the flow rate (mol / min) of ethane discharged from the reactor, and [C ２ H ４ ] indicates the flow rate (mol / min) of ethylene discharged from the reactor, and [CH ４ ] indicates the flow rate (mol / min) of methane discharged from the reactor.

[0071] The propylene yield was calculated by (flow rate of propylene discharged from the reactor (mol / min) / flow rate of propane fed to the reactor (mol / min)×100.

[0072] The average catalyst life of the dehydrogenation catalyst was calculated using a first-order deactivation model. Specifically, the average catalyst life of the dehydrogenation catalyst was calculated using the following formulas 3 and 4.

[0073] In the formula 3, K ｄ is the deactivation rate constant (h －１ ), t represents the reaction time (h), and conv ｓｔａｒｔ indicates the conversion rate (%) of propane at the start of the reaction, and conv ｅｎｄ indicates the propane conversion (%) at the reaction time t (h). The propane conversion at the start of the reaction is the propane conversion of the first plot in Figures 1 to 8.

[0074] In the above formula 4, 1 / k ｄ indicates the average catalyst life (h).

[0075] Example 1 To an aqueous solution containing 35 mg of potassium hydroxide (86% by mass) and 5 g of ion-exchanged water, 8.12 g of TPAOH (20 to 25% by mass, K-free) was added dropwise, and after stirring, 4.2474 g of TEOS was further added dropwise. The resulting solution was stirred at room temperature for 24 hours, and then (NH ４ ) ２ GeF ６ An aqueous solution containing 30.5 mg of the above and 0.2 g of ion-exchanged water was added dropwise, and the mixture was further stirred for 1 hour. ２ PtCl ６ ・6H ２ 15.7 mg of O, Mn(NO ３ ) ２ ・6H ２A mixed aqueous solution containing 26.2 mg of 0 and 0.8 g of ion-exchanged water was added dropwise and stirred for 6 hours, after which 150 μL of ethylenediamine was added and stirred for another hour. The resulting solution was transferred to a PTFE container, sealed in an autoclave, and subjected to hydrothermal synthesis at 175 °C for 96 hours (heating rate: 1 °C / min). After completion of hydrothermal synthesis, the sample was cooled to room temperature, recovered using ion-exchanged water, and centrifuged. The supernatant was removed, and the resulting residue was washed by suction filtration five times with water and acetone, and then dried overnight at 90 °C. The mixture was then calcined in an air atmosphere at 560 °C for 8 hours (heating rate: 2 °C / min) and cooled to room temperature. It was further calcined in an air atmosphere at 600 °C for 2 hours (heating rate: 5 °C / min) to obtain catalyst A1 in which platinum-germanium alloy clusters and manganese oxide were supported in the pores of the silicalite. Table 1 shows the Pt content (mass%) relative to the total mass of the catalyst converted to the amount charged, and the molar ratio of other metals (such as M element) per mole of Pt (the same applies hereinafter to Examples 2 and 3 and Comparative Examples 1 to 3). The Pt content relative to the total mass of the catalyst measured by ICP was 0.43 mass%, and the molar ratios of Ge and Mn per mole of Pt were 1.8 and 3.3, respectively. Table 1 also shows the average particle size of the metal clusters. It was confirmed that the Pt and Ge metal clusters and manganese oxide were located within the sinusoidal channels of the 10-membered ring.

[0076] [Example 2] Mn(NO ３ ) ２ ・6H ２ Catalyst A2, in which platinum-germanium alloy clusters were supported in the pores of silicalite, was obtained in the same manner as in Example 1, except that O was not used. The Pt content relative to the total mass of the catalyst, as measured by ICP, was 0.46 mass%, and the molar ratio of Ge per mole of Pt was 1.6. It was confirmed that the Pt and Ge metal clusters were located within the sinusoidal channels of the 10-membered ring.

[0077] [Example 3] Mn(NO ３ ) ２ ・6H ２ Instead of O, SnCl ５ ・5H ２Catalyst A3, in which platinum-germanium alloy clusters and tin oxide were supported in the pores of silicalite, was obtained in the same manner as in Example 1, except that 50 mg of O was used. It was confirmed that the Pt and Ge metal clusters and tin oxide were located in the sinusoidal channels of the 10-membered ring.

[0078] Comparative Example 1 To an aqueous solution containing 35 mg of KOH and 5 g of ion-exchanged water, 8.12 g of TPAOH was added dropwise, and after stirring, 4.2474 g of TEOS was further added dropwise. The resulting solution was stirred at room temperature for 24 hours, and then subjected to H ２ PtCl ６ ・6H ２ 16.0 mg of O, Mn(NO ３ ) ２ ・6H ２ A mixed aqueous solution containing 39.3 mg of HCl and 1.0 g of ion-exchanged water was added dropwise and stirred for 6 hours. Then, 150 μL of ethylenediamine was added and stirred for another hour. The resulting solution was transferred to a PTFE container, sealed in an autoclave, and subjected to hydrothermal synthesis at 175 °C for 96 hours (heating rate: 1 °C / min). After hydrothermal synthesis, the sample was cooled to room temperature, recovered using ion-exchanged water, and centrifuged. The supernatant was removed, and the resulting residue was washed by suction filtration five times with water and acetone, and then dried overnight at 90 °C. The mixture was then calcined in an air atmosphere at 560 °C for 8 hours (heating rate: 2 °C / min) and cooled to room temperature. It was further calcined in an air atmosphere at 600 °C for 2 hours (heating rate: 5 °C / min) to obtain catalyst B1, in which platinum metal and manganese oxide were supported within the pores of the silicalite. The Pt content relative to the total mass of the catalyst, as measured by ICP, was 0.40% by mass. The Pt metal and manganese oxide were found to be located within sinusoidal channels of 10-membered rings.

[0079] [Comparative Example 2] Mn(NO ３ ) ２ ・6H ２ Catalyst B2, in which platinum metal was supported in the pores of silicalite, was obtained in the same manner as in Comparative Example 1, except that O was not used. The Pt content relative to the total mass of the catalyst measured by ICP was 0.43 mass%. It was confirmed that the Pt metal was located in the sinusoidal channels of the 10-membered ring.

[0080]

[0081] [Example 4] (NH ４ ) ２ GeF ６ Instead of CuCl ２ Catalyst A4, in which platinum-copper alloy clusters were supported in the pores of silicalite, was obtained by the same method as in Example 2, except that 19.3 mg of the platinum-copper alloy clusters were used. Table 2 shows the Pt content (mass %) relative to the total mass of the catalyst converted into the charged amount, and the molar ratio of other metals (M element, etc.) per mol of Pt (the same applies hereinafter to Examples 5 to 12 and Comparative Examples 3 to 11). Note that M1 in Table 2 refers to metal elements other than Pt, M element, Mn, and Sn.

[0082] [Comparative Example 3] (NH ４ ) ２ GeF ６ Instead of CoCl ２ ・6H ２ Catalyst B3 in which platinum and cobalt were supported in the pores of silicalite was obtained in the same manner as in Example 2, except that 32.7 mg of O was used.

[0083] [Comparative Example 4] (NH ４ ) ２ GeF ６ Instead of NiCl ２ ・6H ２ Catalyst B4, in which platinum and nickel were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 33.2 mg of O was used.

[0084] [Example 5] (NH ４ ) ２ GeF ６ Instead of In(NO ３ ) ３ ・nH ２ Catalyst A5, in which platinum and indium were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 62.9 mg of 0 was used.

[0085] [Comparative Example 5] (NH ４ ) ２ GeF ６ Instead of Pb(NO ３ )２ Catalyst B5, in which platinum and lead were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 45.3 mg of lead was used.

[0086] [Example 6] (NH ４ ) ２ GeF ６ Instead of FeCl ３ ・6H ２ Catalyst A6, in which platinum and iron were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 37.2 mg of O was used.

[0087] Example 7 (NH ４ ) ２ GeF ６ Instead of RuCl ３ ・nH ２ Catalyst A7, in which platinum and ruthenium were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 33.7 mg of 0 was used.

[0088] [Example 8] (NH ４ ) ２ GeF ６ Instead of (NH ４ ) ReO ４ Catalyst A8, in which platinum and rhenium were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 36.9 mg of the above was used.

[0089] [Comparative Example 6] (NH ４ ) ２ GeF ６ Instead of Zn(NO ３ ) ２ ・6H ２ Catalyst B6, in which platinum and zinc were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 41.1 mg of 0 was used.

[0090] [Comparative Example 7] (NH ４ ) ２ GeF ６ Instead of SbF ３ Catalyst B7, in which platinum and antimony were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 24.8 mg of the above was used.

[0091] [Comparative Example 8] (NH ４ ) ２ GeF ６ Instead of BiCl ３ Catalyst B8, in which platinum and bismuth were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 44.2 mg of the above was used.

[0092] [Comparative Example 9] (NH ４ ) ２ GeF ６ Instead of La(NO ３ ) ３ ・6H ２ Catalyst B9, in which platinum and lanthanum were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 59.0 mg of 0 was used.

[0093] [Comparative Example 10] (NH ４ ) ２ GeF ６ Instead of Ce(NO ３ ) ３ ・6H ２ A catalyst B10 in which platinum and cerium were supported in the pores of silicalite was obtained in the same manner as in Example 2, except that 60.3 mg of 0 was used.

[0094] [Comparative Example 11] (NH ４ ) ２ GeF ６ Instead of H ２ TeO ４ ・2H ２ A catalyst B11 in which platinum and tellurium were supported in the pores of silicalite was obtained in the same manner as in Example 2, except that 31.7 mg of O was used.

[0095] [Example 9] H ２ PtCl ６ ・6H ２ The mixture containing O further contains FeCl ２ ・6H ２ Catalyst A9, in which platinum, germanium, and iron were supported in the pores of silicalite, was obtained in the same manner as in Example 2, except that 12.4 mg of O was added. The molar ratio of other metals (M element, etc.) per 1 mol of Pt, calculated as the charged amount, was 4.5 mol of Ge and 1.5 mol of Fe.

[0096] [Example 10] H ２ PtCl ６ ・6H ２ The mixture containing O further contains CuCl ２ Catalyst A10, in which platinum, germanium, and copper were supported in the pores of silicalite, was obtained by the same method as in Example 2, except that 6.4 mg of the above was contained. The molar ratio of other metals (M element, etc.) per 1 mol of Pt, calculated as the charged amount, was 4.5 mol of Ge and 1.5 mol of Cu.

[0097] [Example 11] H ２ PtCl ６ ・6H ２ The mixture containing O further contains Ga(NO ３ ) ３ ・nH ２ A catalyst A11 in which platinum, germanium, and gallium were supported in the pores of silicalite was obtained in the same manner as in Example 2, except that 18.4 mg of O was contained.

[0098] [Example 12] H ２ PtCl ６ ・6H ２ The mixture containing O was further treated with RuCl ３ ・nH ２ Catalyst A12 in which platinum, germanium, and gallium were supported in the pores of silicalite was obtained in the same manner as in Example 2, except that 11.2 mg of O was contained. The molar ratio of other metals (M element, etc.) per 1 mol of Pt, calculated as the charged amount, was 4.5 mol of Ge and 1.5 mol of Ru.

[0099]

[0100] A propane dehydrogenation reaction was carried out using catalysts A1, A2, B1, and B2. The reaction conditions were as follows: Catalyst loading: 30 mg (150 mg for catalysts B1 and B2). Pretreatment conditions: Hydrogen was circulated through the catalyst layer at 10 mL / min, and pretreatment was carried out at 700°C for 5 hours. Reaction conditions: A mixed gas of propane and helium with a volume ratio of 1:2 was circulated through the catalyst layer at 7.5 mL / min, and the reaction was carried out at 600°C or 630°C. The reaction pressure was 0.1 MPa (atmospheric pressure).

[0101] The changes in propane conversion and propylene selectivity over time at a reaction temperature of 630°C for catalysts A1, A2, B1, and B2 are shown in Figure 1. The catalysts of Examples 1 and 2, which contained platinum, M, and MFI zeolite, had higher propane conversion and propylene selectivity over any reaction time, compared to the catalysts of Comparative Examples 1 and 2, which did not contain platinum, M, or MFI. Furthermore, the catalyst of Example 1, which further contained manganese oxide, showed less decrease in propane conversion over time than the catalyst of Example 2.

[0102] Table 1 shows the 1 / k ｄ It was found that the catalysts of Examples 1 and 2, which contained platinum element, M element, and MFI zeolite, had a longer average catalyst life than the catalysts of Comparative Examples 1 and 2, which did not contain any of platinum element, M element, and MFI zeolite. Table 1 also shows the carbon amounts of catalysts A1, A2, B1, and B2 after 19.5 hours of reaction at a reaction temperature of 600°C. It was found that the inclusion of manganese oxide suppressed coking.

[0103] A propane dehydrogenation reaction was carried out using catalysts A4 to A8, B2, and B3 to B11. The reaction conditions were as follows: Catalyst loading: 50 mg Pretreatment conditions: Hydrogen was circulated through the catalyst layer at 10 mL / min, and pretreatment was carried out at 700°C for 5 hours. Reaction conditions: A mixed gas of propane and helium with a volume ratio of 1:2 was circulated through the catalyst layer at 7.5 mL / min, and the reaction was carried out at 600°C. The reaction pressure was 0.1 MPa (atmospheric pressure).

[0104] The changes in propane conversion and propylene selectivity over time for Catalyst A4 and Catalysts B2 to B4 are shown in Figure 2. The catalyst of Example 4, which contained platinum, M, and MFI zeolite, had a higher propylene yield after 5 hours of reaction than the catalysts of Comparative Examples 2 to 4, which contained platinum and MFI zeolite but no M.

[0105] The changes in propane conversion and propylene selectivity over time for Catalyst A5, Catalyst B2, and Catalyst B5 are shown in Figure 3. The catalyst of Example 5, which contained platinum, M, and MFI zeolite, had a higher propylene yield after 15 hours of reaction, compared to the catalysts of Comparative Examples 2 and 5, which contained platinum and MFI zeolite but no M.

[0106] The changes in propane conversion and propylene selectivity over time for Catalysts A6 to A8 and Catalyst B2 are shown in Figure 4. The catalysts of Examples 6 to 8, which contained platinum, M, and MFI zeolite, had a higher propylene yield after 5 hours of reaction, compared to the catalyst of Comparative Example 2, which contained platinum and MFI zeolite but no M.

[0107] The changes in propane conversion and propylene selectivity over time for catalysts B2 and B6 to B8 are shown in Figure 5. The catalysts of Comparative Examples 6 to 8, which contained platinum element and MFI zeolite and a metal element other than the M element, had propylene yields at the same level or lower after 5 hours of reaction, compared to the catalyst of Comparative Example 2, which contained only platinum element and MFI zeolite.

[0108] The changes in propane conversion and propylene selectivity over time for catalysts B2, B9 to B11 are shown in Figure 6. The catalysts of Comparative Examples 9 to 11, which contained platinum element and MFI zeolite and a metal element other than the M element, had a lower propylene yield after 5 hours of reaction, compared to the catalyst of Comparative Example 2, which contained only platinum element and MFI zeolite.

[0109] A propane dehydrogenation reaction was carried out using catalysts A1, A2, A3, and A9 to A12. The reaction conditions were as follows: Catalyst loading: 30 mg Pretreatment conditions: Hydrogen was circulated through the catalyst layer at 10 mL / min, and pretreatment was carried out at 700°C for 5 hours. Reaction conditions: A mixed gas of propane and helium with a volume ratio of 1:2 was circulated through the catalyst layer at 7.5 mL / min, and the reaction was carried out at 630°C.

[0110] The changes in propane conversion and propylene selectivity over time for catalysts A1, A2, A9, and A10 are shown in Figure 7. The catalysts of Examples 1, 2, 9, and 10, which contained platinum, M, and MFI zeolite, suppressed the decrease in propane conversion over time. Furthermore, the propylene selectivity was consistently at a high level.

[0111] The changes in propane conversion and propylene selectivity over time for catalysts A2, A3, A11, and A12 are shown in Figure 8. The catalysts of Examples 2, 3, 11, and 12, which contained platinum, M, and MFI zeolite, suppressed the decrease in propane conversion over time. Furthermore, the propylene selectivity was consistently at a high level.

[0112] Tables 1 and 2 show the 1 / k ｄ It was found that the catalysts of Examples 3, 5, and 9 to 12, which contained platinum element, M element, and MFI zeolite, had a longer average catalyst life than the catalysts of Comparative Examples 3 to 6, 9, and 10, which contained platinum element and MFI zeolite but did not contain M element.

[0113] The dehydrogenation catalyst according to the present invention is useful because it enables propylene to be produced over a long period of time.

Claims

1. A dehydrogenation catalyst for producing propylene by a dehydrogenation reaction of propane, comprising an MFI zeolite, a platinum element, and an M element, wherein the MFI zeolite has a molar ratio of silicon to aluminum element (Si / Al) of 50 or more, the M element being one or more elements selected from the group consisting of germanium element, copper element, indium element, iron element, ruthenium element, and rhenium element, and the platinum element and the M element are located within the channels of the MFI zeolite.

2. The dehydrogenation catalyst according to claim 1, wherein the platinum element and the M element form an alloy cluster.

3. The dehydrogenation catalyst according to claim 1 or 2, further comprising manganese oxide or tin oxide, said manganese oxide or tin oxide being located within the channels of said MFI zeolite.

4. The dehydrogenation catalyst according to claim 1 or 2, wherein the MFI zeolite does not contain aluminum element.

5. The dehydrogenation catalyst according to claim 1 or 2, wherein the M element is germanium element.

6. A method for producing a dehydrogenation catalyst according to claim 1 or 2, comprising: a hydrothermal synthesis step of hydrothermally synthesizing a mixed liquid containing a structure-directing agent, a compound containing a platinum element, the compound containing an M element, and a compound containing a silicon element; an oxidation-calcination step of oxidizing and calcining the solid obtained in the hydrothermal synthesis step in an oxidizing gas atmosphere to remove the structure-directing agent; and a reduction-calcination step of reducing and calcining the calcined body obtained in the oxidation-calcination step in a reducing gas atmosphere.

7. A method for producing propylene, comprising contacting a feed gas containing propane with the dehydrogenation catalyst according to claim 1 or 2.

8. The method for producing propylene according to claim 7, wherein the reaction temperature is 550 to 650°C.

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