Catalyst for Propylene Production

Abstract

The present invention aims to provide a catalyst that maintains high catalytic performance and can be used stably when producing propylene by gas-phase catalytic reaction using ethylene and / or ethanol as raw materials. [Solution] A catalyst containing zeolite in which the circularity of each particle is calculated from the area of ​​the portion corresponding to the zeolite particle in the image obtained by binarizing the SEM image and splitting the area where two or more particles overlap is 0.878 or higher.

Description

Technical Field

[0001] As a method for producing propylene, the steam cracking method of naphtha and the fluid catalytic cracking method of vacuum gas oil have been generally practiced. However, in the field of manufacturing chemical raw materials in recent years, in order to suppress carbon dioxide generation and prepare for the future rise or depletion of petroleum resources, it has been required to convert chemical raw materials from petroleum-based resources to non-edible biomass resources. In particular, there is a demand for technology to more efficiently produce polypropylene, a typical general-purpose resin, from bioethanol, a biomass resource.

[0002] In Patent Document 1, an acid catalyst, particularly zeolite, is used as a method for producing olefins from ethanol. Further, Patent Document 2 discloses a method for producing propylene from ethanol using zeolite supported with zirconium as a catalyst. Furthermore, Patent Document 3 discloses a method using phosphate-based zeolite, Patent Document 4 discloses a method using an aluminosilicate composed of an 8-membered ring or a 9-membered ring having a pore diameter of less than 0.5 nm as a catalytic active ingredient, Patent Document 5 discloses a method using a zeolite-containing catalyst composed of zeolite, a phosphoric acid aluminum-containing binder, and a matrix, and Patent Document 6 discloses a method using a zeolite-containing catalyst composed of a modified zeolite treated with an aqueous phosphate-containing solution and a matrix.

[0003] In order to make the production of lower olefins by zeolite practical, it is necessary to significantly extend the catalyst life. Also, the catalyst life is a major problem common to reaction processes using zeolite as a catalyst, and particularly, the more severe the reaction conditions, the more significant the decrease in catalyst performance. The decrease in catalyst performance causes problems such as a decrease in the yield of the target product and an increase in the load on the purification process due to changes in the product distribution. Such a decrease in catalyst performance is mainly caused by pore blockage due to the deposition of carbonaceous substances called coke and the disappearance of acidic properties due to the desorption of aluminum components in the zeolite crystal framework by contact with high-temperature steam, etc.

[0004] Coke formation is believed to occur under harsh reaction conditions through the sequential progression of side reactions such as polymerization, cyclization, and aromatization of lower olefins. On the other hand, zeolites have clearly defined pores of a specific size derived from their crystal structure, and are characterized by shape-selective reactions proceeding at acid sites within these pores. Therefore, if zeolites without pores of 12 member rings or more are used, the spatial constraints limit the sequential side reactions that lead to coke formation within the pores. However, it is thought that a certain proportion of acid sites exist on the outer surface of zeolites, which are not restricted by pore shape, and that coke formation occurs through non-selective reactions as a result (Non-Patent Literature 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-290991 [Patent Document 2] Japanese Patent Publication No. 2010-202612 [Patent Document 3] Japanese Patent Publication No. 2007-191444 [Patent Document 4] Japanese Patent Publication No. 2007-291076 [Patent Document 5] Japanese Patent Application Publication No. 4-354541 [Patent Document 6] Japanese Patent Application Publication No. 5-64743 [Non-Patent Document 1] Journal of Chemical Engineering of Japan, vol. 42, pp. S162-S167(2009) [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to provide a catalyst that maintains high catalytic performance and can be used stably when producing propylene by gas-phase catalytic reaction using ethylene and / or ethanol as raw materials. [Means for solving the problem]

[0007] The inventors of this invention, after diligent research to solve the above problems, have found that the above problems can be solved by using a catalyst with a circularity of 0.878 or higher when producing propylene from ethylene and / or ethanol as raw materials.

[0008] In other words, the gist of the present invention is, 1) In SEM images acquired using a scanning electron microscope (SEM) under conditions of an acceleration voltage of 25kV and a magnification of 10,000x, where the area ratio of catalyst granules to the entire image is 30% to 70%, A catalyst having a zeolite in which the circularity of each particle, calculated from the area of ​​the portion corresponding to the zeolite particle in the image obtained by binarizing the SEM image and dividing the portion where two or more particles overlap, is 0.878 or higher. Here, circularity is calculated using the following formulas (1), (2), and (3) from the area and perimeter values ​​of each particle, and is the average of all particles captured in the image. Here, area refers to the area of ​​the part corresponding to the zeolite particle, and perimeter refers to the length of the outer circumference of the part corresponding to the zeolite particle. Equivalent diameter is the diameter of a perfect circle with the same area, and equivalent perimeter is the circumference of a perfect circle with the same area. (((Area) / π)^1 / 2) × 2 = (Equivalent diameter of a circle) ... (1) π * (equivalent diameter of a circle) = (equivalent circumference of a circle) ... (2) (Circularity) = (Equivalent circumference of a circle) / (Circumference) ... (3) 2) The catalyst according to 1), wherein the circularity is 0.916 or greater. 3) The catalyst is a zeolite of CHA structure with a surface area average diameter greater than 0 and not more than 0.3 μm, and is the catalyst according to 1) or 2) used for propylene production. 4) The catalyst according to any one of 1) to 3), wherein the zeolite is a zeolite of CHA structure不含phosphorus. 5) The catalyst according to any one of 1) to 4), wherein the zeolite has a SiO2 / Al2O3 molar ratio of 1 or more and 100 or less. 6) The catalyst according to any one of 1) to 5), wherein the zeolite is SSZ-13 zeolite. 7) The catalyst according to any one of 1) to 6), which is formed by shaping the zeolite. 8) A method for producing propylene using ethanol, ethylene, or a mixture of ethanol and ethylene as a raw material and the catalyst according to any one of 1) to 7). 9) The method for producing propylene according to 8), which has a catalyst regeneration step. 10) The method for producing propylene according to 8) or 9), wherein the regeneration step of the catalyst is a regeneration step using either oxygen or hydrogen, or both gases.

Advantages of the Invention

[0009] According to the present invention, when producing propylene using ethylene or / and ethanol as a raw material, the raw material conversion rate can be maintained high, and propylene can be stably produced.

Brief Description of the Drawings

[0010] [Figure 1] Figure 1 is a diagram showing the XRD chart of Catalyst 1 produced in Example 1 (Zeolite A). [Figure 2]FIG. 2 is a diagram showing the ethylene conversion rate with respect to the reaction time (hr) when a catalytic reaction is carried out using the catalysts according to Example 1 (zeolite A), Example 2 (zeolite B), Example 4 (zeolite C), and Comparative Example 1 (zeolite D). [Mode for Carrying Out the Invention]

[0011] Hereinafter, embodiments of the catalyst according to the present invention will be described.

[0012] [Measurement Method of Circularity (1)] The method for obtaining the SEM image will be described. Using a scanning electron microscope (SEM), an SEM image of the dry granules for catalyst production or the catalyst is taken under the conditions of an acceleration voltage of 25 kV and a magnification of 10,000 times. Although there is no particular specification for the method of preparing the sample used for imaging, it is prepared by placing the granules on carbon tape and then removing the excess with compressed air or the like. At that time, the amount of granules remaining on the carbon tape should be such that the ratio of the area of the granule portion occupying the entire image is 30% to 70% when measured under the above SEM measurement conditions. In the present invention, in order to analyze the shape of the particles, it is preferable to take the SEM image as a backscattered electron image and binarize the obtained SEM image, so that the contour of the particles becomes clear and the shape can be analyzed more accurately. The colors for binarization are particularly preferably white and black in order to clarify the contour of the particles. Examples of the method for binarizing the obtained SEM image include a method of adjusting the contrast and brightness to emphasize the light and dark, and a method of performing image processing using image analysis software to clarify the contour.

[0013] The method for processing the SEM image in the present invention is not particularly specified as long as the particle shape can be analyzed. As an example, a series of processing procedures described in the "MIPAR User Manual - v4.3_Last update: Jul 13, 2023" (hereinafter referred to as the user manual), an image processing software MIPAR manufactured by MIPAR Software LLC, described below can be mentioned.

[0014] First, the "Histgram Equalization" process described on page 161 of the user manual was performed with Method set to Uniform, tiles set to 114, and enhancement set to 0.01. Secondly, the "Adjust Contrast" process described on page 159 of the user manual was performed with Mode set to Manual, Low Level to 0, High Level to 255, and Gamma value to 3.834. Thirdly, the "Basic Threshold" process described on page 240 of the user manual was performed with Type set to Value, Mode to Monual, Select to Bright, and Value to 98. Fourthly, the "Uniform Dilation" process described on page 290 of the user manual was performed, with Units set to px and Depth to 6. This was then saved as a Companion Image. Fifth, the "Adaptive Threshold" process described on page 243 of the user manual was performed with Select set to Bright, Statistic set to Box Mean, Dynamic set to Off, Mask set to Companion Image, Operation set to Percentage, Percentage set to 98.925, and Window Size set to 30. Sixth, the "Smart Dilation" process described on page 291 of the user manual was performed with a Threshold of 4 and Iterations of 10. Seventh, I performed the "Separate Features" process described on page 302 of the user manual, setting Maximum Line Length to None, checking Edge Lines, Resolution to Low, Thickness to 2, and Separation to 1. Finally, the "Reject Features" process described on page 317 of the user manual was performed with Feature Parameter set to Area, Features set to Objects, Edges set to Include, Units set to Pixels, Threshold Value of Area set to 20, Type set to Peject Features < / =, and Neighbirhood Conditionals set to None.

[0015] The circularity of each particle was calculated from the processed image in this way. The circularity is calculated using the following formulas (1), (2), and (3) from the area and perimeter values of each particle, and is the average of all the particles shown in the image. Here, the area refers to the area of the part specified as white for each particle, and the perimeter refers to the length of the outer perimeter of the part specified as white for each particle. The equivalent circle diameter refers to the diameter of a perfect circle having the same area as the area of each particle, and the equivalent circle perimeter refers to the circumference of a perfect circle having the same area as the area of each particle. (((Area) / π)^1 / 2)×2 = (Equivalent circle diameter) ···(1) π*(Equivalent circle diameter) = (Equivalent circle perimeter) ···(2) (Circularity) = (Equivalent circle perimeter) / (Perimeter) ···(3)

[0016] The reaction to synthesize propylene using ethylene and / or ethanol as raw materials is a reaction that involves carbon deposition on the zeolite surface, and the conversion rate decreases as carbon deposition progresses. The inventors of this invention believe that a zeolite with a high degree of circularity allows the reaction gas to flow freely between the zeolite particles without stagnation, thereby reducing carbon deposition and suppressing the decrease in the conversion rate. The lower limits of the preferred range for circularity are, in order, 0.878, 0.900, 0.905, 0.910, 0.915, 0.916, 0.917, 0.918, and 0.919, with a value of 0.920 or higher being particularly preferred. Furthermore, the preferred upper limits for the circularity range are, in order, 1.00, 0.995, 0.990, 0.985, 0.980, 0.979, 0.978, 0.977, 0.976, and 0.975, with a particularly preferred range of 0.974 or less. Based on the above, the desirable range for circularity is 0.878 to 1.00, more preferably 0.878 to 0.995, more preferably 0.900 to 0.990, more preferably 0.905 to 0.985, more preferably 0.910 to 0.980, 0.915 to 0.979, 0.916 to 0.978, 0.917 to 0.977, 0.918 to 0.976, more preferably 0.919 to 0.975, and particularly preferably 0.920 to 0.974. This range allows for maintaining a high raw material conversion rate over the long term, enabling stable production of propylene. Furthermore, the inventors of this invention believe that this range also allows for maintaining selectivity over the long term and improving the regeneration efficiency when performing the catalyst regeneration process described later.

[0017] [Zeolite] Zeolites refer to crystalline materials in which tetrahedral TO4 units (where T is the central atom) are linked three-dimensionally by sharing an O atom, forming open, regular micropores. Specifically, they include silicates, phosphates, germanium salts, arsenates, etc., as listed in the structural committee data collection of the International Zeolite Association (IZA). Here, silicates include, for example, aluminosilicate, gallosilicate, ferricilicate, titanosilicate, borosilicate, etc., phosphates include, for example, aluminophosphate, gallophosphate, beryllophosphate, etc., germanium salts include, for example, aluminogermanium salt, etc., and arsenates include, for example, aluminoarsenate, etc. Furthermore, aluminophosphates include, for example, silicoaluminophosphates in which the T atom is partially substituted with Si, and those containing divalent or trivalent cations such as Ga, Mg, Mn, Fe, Co, Zn, etc.

[0018] The framework density of the zeolite is not particularly limited, but is preferably 18 or less, more preferably 17 or less, and the lower limit is usually 13 or more, preferably 14 or more. Here, framework density (unit: T / nm) 3 ) refers to the unit volume (1 nm) of zeolite. 3 This refers to the number of T atoms (atoms other than oxygen that make up the zeolite skeleton) present per unit area, and this value is determined by the structure of the zeolite. When zeolites are used as catalysts for propylene production, they tend to exhibit high activity, so the preferred skeleton structures of zeolites are AFX, CHA, ERI, LEV, RHO, and RTH, with CHA being the most preferred skeleton structure.

[0019] Examples of zeolites with a CHA structure include silicates and phosphates. As mentioned above, examples of silicates include aluminosilicate, gallosilicate, ferricilicate, titanosilicate, borosilicate, etc., and examples of phosphates include aluminophosphate (ALPO-34) composed of aluminum and phosphorus, and silicoaluminophosphate (SAPO-34) composed of silicon, aluminum and phosphorus. Among these, aluminosilicate and silicoaluminophosphate are preferred, and aluminosilicate is more preferred.

[0020] When the zeolite is a silicate, the SiO2 / M2O3 (where M represents a trivalent metal such as aluminum, gallium, iron, or boron) or SiO2 / TiO2 molar ratio is preferably 1, 5, 10, and 15 or higher as lower limits, more preferably 20 or higher, and preferably 100, 50, and 40 or lower as upper limits, more preferably 30 or lower. Therefore, the preferred molar ratio ranges are 1 to 100, 5 to 100, 10 to 50, 15 to 40, and more preferably 20 to 30. If this value is too low, the durability of the catalyst tends to decrease, and if it is too high, the catalytic activity tends to decrease. The composition of the zeolite can be controlled by changing the molar ratio of the raw materials. For example, in the case of aluminosilicate, the SiO2 / Al2O3 molar ratio of the resulting zeolite is approximately equal to the molar ratio of the silica raw material to the alumina source.

[0021] The aforementioned zeolite can be synthesized by known and commonly used methods, such as hydrothermal synthesis, which involves preparing an aqueous gel of a crystalline precursor containing silica raw materials, a heteroatom source, and an alkali (earth) metal element source, and then heating it, specifically by using the method described in Japanese Patent No. 5810967. The zeolite used in this invention can be any zeolite having the aforementioned physical properties and composition, and commercially available products such as SSZ-13 zeolite (manufactured by ACS Material) can be used.

[0022] The area-average diameter of the zeolite used in the present invention is not particularly limited, but considering the maintenance of high catalytic performance when the zeolite is used as a propylene production catalyst as described later, a small area-average diameter is preferable. In this invention, the area-average diameter is calculated from the area of ​​all particles captured in an image taken with a transmission electron microscope (hereinafter abbreviated as "TEM") or scanning electron microscope (SEM) using the following formula (4). Here, area refers to the area of ​​the white portion of each particle, and the average value of the area of ​​all particles means the value obtained by dividing the area of ​​all particles in the image by the number of particles. (((Average area of ​​all particles) / π)^1 / 2)×2=(Area-average diameter) ···(4)

[0023] While it is difficult to synthesize zeolites with the desired shape used in this invention, it is possible to synthesize them by using various manufacturing methods, such as adjusting the synthesis temperature conditions in the zeolite manufacturing process or adjusting the pH of the mixture to a specific value. It is also possible to adjust the shape by pulverizing the raw material zeolite and then recrystallizing it. The method of preparing the zeolite is not particularly limited, but considering that a catalyst with a more desirable circularity can be obtained and that pulverization can break the crystals (amorphization), resulting in a loss of desired performance, it is preferable to prepare the zeolite by pulverizing it followed by recrystallization.

[0024] (Zeolite used as a raw material for grinding) The raw material zeolite can have an area-average diameter of 0.6 μm or more. In this invention, from the viewpoint of obtaining fine zeolite of 0.6 μm or less in the end, it is preferable to use raw material zeolite with a particle size close to 0.6 μm in area-average diameter as the starting material, from the viewpoint of simplifying the grinding process and suppressing amorphization due to the grinding process. From this viewpoint, the lower limit of the preferred range for the area-average diameter of the raw material zeolite used in the grinding process is preferably 0.60 μm, and the upper limit of the area-average diameter is preferably 10 μm or less, preferably 5.0 μm or less, preferably 2.0 μm or less, preferably 1.5 μm or less, more preferably 1.0 μm or less, and most preferably 0.80 μm or less. Therefore, the preferred range for the area-average diameter of the raw material zeolite is more preferably 0.60 μm to 10 μm, more preferably 0.60 μm to 5.0 μm, more preferably 0.60 μm to 2.0 μm, more preferably 0.60 μm to 1.5 μm, more preferably 0.60 μm to 1.0 μm, and most preferably 0.30 μm to 0.80 μm.

[0025] (Zeolite crushing process) The pulverization process can be carried out by any method that allows the raw material zeolite to be pulverized in such a way that fine zeolite with an average area diameter of 0.6 μm or less after processing can be obtained. Examples of such pulverization methods include bead mills, ball mills, planetary ball mills, and jet mills. Of these, bead mills are preferred from the viewpoint of minimizing the amorphous formation of the zeolite during pulverization. A bead mill is a device that typically uses ceramic beads with a particle size of 30 to 1000 μm as a pulverization medium to perform pulverization and crushing. In this way, because micro-beads are used, unlike ball mills and planetary ball mills, the powder to be processed collides with the beads frequently, and the force applied to the particles during each collision is small, so efficient pulverization can be achieved while suppressing the amorphous formation of the surface of the raw material zeolite. However, even when using a bead mill, amorphous formation of the zeolite is unavoidable, and a certain degree of amorphous formation occurs. While there are no particular limitations on the amount of ceramic beads to be added, from the viewpoint of efficiently grinding the zeolite while suppressing its amorphous state, a bulk density of 60-80% of the volume in the bead mill grinding chamber is preferred, and 70% is more preferred.

[0026] Furthermore, the grinding process can be carried out wet or dry, but from the viewpoint of ease of grinding and uniformity of zeolite particle size, it is preferable to carry it out wet. When grinding is carried out wet, the raw material zeolite is dispersed in a dispersion medium. Examples of such dispersion mediums include water, alcohol such as ethanol, and mixed solvents thereof. Of these, water is preferred from the viewpoint of ease of handling and cost. Also, alcohol such as ethanol is preferred from the viewpoint of preventing re-aggregation of the ground zeolite. From the viewpoint of uniformly dispersing the raw material zeolite and ground zeolite in the dispersion medium, surfactants, anti-aggregation agents, etc. may be added as needed.

[0027] The grinding time can be appropriately determined depending on the grinding method, the desired particle size, etc. Note that the degree of amorphization tends to increase as the grinding time increases.

[0028] (Recrystallization of zeolite) The zeolite that has been pulverized as described above may be recrystallized. In this case, it is preferable to recrystallize it by placing it in an alkaline solution at 15°C to 45°C, and the recrystallization process should be carried out so that a zeolite is obtained in which the ratio of the degree of crystallinity after recrystallization (B) to the degree of crystallinity before recrystallization (A) (B / A) is 1.2 or higher.

[0029] The alkaline solution used in this invention is not particularly limited, as long as it has a pH of 13 or higher and is capable of promoting the recrystallization of zeolite that has been amorphous by grinding. Examples of such alkaline solutions include aluminosilicate solutions or similar solutions as described in Patent Document 1, silicate solutions or similar solutions as described in Patent Document 2, and aqueous solutions of alkali metal hydroxides. Of these, aqueous solutions of alkali metal hydroxides are preferred from the viewpoint of cost and from the viewpoint of suppressing crystal growth. Examples of alkali metal hydroxides include LiOH, NaOH, and KOH, with NaOH and KOH being preferred, and NaOH being more preferred. In this invention, it has been found that recrystallization can be performed even with just an aqueous solution of alkali metal hydroxide, without using special solutions such as conventional aluminosilicate solutions or silicate solutions. It is believed that a portion of the amorphous part of the pulverized zeolite dissolves in an aqueous solution of alkali metal hydroxide, effectively transforming it into an aluminosilicate solution. This then promotes recrystallization, thereby suppressing the increase in particle size without crystal growth, similar to the case when using an aluminosilicate solution.

[0030] When using an aqueous solution of alkali metal hydroxide as the alkaline solution, the concentration of alkali metal hydroxide can be appropriately determined considering the content of the pulverized zeolite, the degree of crystallinity of the zeolite, and the treatment of the waste liquid after recrystallization. However, if the concentration is too low, recrystallization tends to become difficult, and if it is too high, the viscosity of the alkaline solution tends to be high and the diffusion of alkali metal ions tends to decrease too much. Therefore, from the viewpoint of efficiently improving the degree of crystallinity, a concentration of 0.5 to 4 M is preferred, 0.75 to 3 M is more preferred, and 1 to 2.5 M is particularly preferred.

[0031] The aluminosilicate solution preferably has the composition aM2O / bAl2O3 / cSiO2 / dH2O (wherein M represents K or Na, a / d is 0.001 to 0.040, b / d is 0.000003 to 0.000250, and c / d is 0.0001 to 0.1000). Furthermore, when the Si / Al ratio of the zeolite is 2 or less, it is preferable that a / d is 0.0100 to 0.0390, b / d is 0.0000050 to 0.0002400, and c / d is 0.000330 to 0.100000. When the Si / Al ratio of the zeolite is greater than 2 and 3 or less, it is preferable that a / d is 0.00160 to 0.00500, b / d is 0.0000031 to 0.0001000, and c / d is 0.000500 to 0.003000.

[0032] The silicate solution preferably has a composition of aM2O / bSiO2 / cH2O (wherein M represents an alkali metal, the molar ratio of a / c is 0.001 to 0.040, and the molar ratio of b / c is 0.0001 to 0.1000).

[0033] In this invention, when recrystallizing pulverized zeolite, it is preferable to carry out the process in an alkaline solution, with a temperature of 15°C to 45°C. Preferably, it is 20°C to 45°C, more preferably 30°C to 45°C, and most preferably 40°C to 45°C. Below 15°C, the recrystallization rate is slow, resulting in low productivity, while above 45°C, although the recrystallization rate is fast, it tends to be difficult to obtain productivity that justifies the energy cost of heating.

[0034] If heating within such a temperature range is required, conventionally known heating devices can be used. For example, methods include, but are not limited to, installing a heater in the mixture of alkaline solution and zeolite, or installing a heater around the mixing tank containing the mixture. Furthermore, it is preferable to heat the alkaline solution, i.e., the mixture, while controlling its temperature so that it falls within a predetermined temperature range.

[0035] The weight ratio (W / Z) of the pulverized zeolite (Z) to the alkaline solution (W) during the recrystallization process is not particularly limited, but from the viewpoint of production efficiency, it is preferable that W / Z is 0.1 or more and 30 or less, and more preferably 2 or more and 5 or less.

[0036] In this invention, the recrystallization treatment can be carried out by either letting the mixture stand or stirring after mixing the pulverized zeolite with the alkaline solution. Stirring tends to improve the rate of recrystallization. The processing time for the recrystallization treatment should be determined appropriately according to various conditions, so as to achieve the desired degree of recrystallization described later.

[0037] In this invention, the degree of crystallinity can be determined from the peak intensity ratio when XRD is measured. When the intensity of the strongest peak measured by XRD before recrystallization is set to 100%, the recrystallization treatment is performed so that the peak intensity at the same 2θ position when XRD is measured after recrystallization is 30% or more. The degree of crystallinity of the zeolite after recrystallization treatment is sufficient as long as it has crystallinity that can withstand various applications, but from the viewpoint of obtaining fine zeolite with better crystallinity in order to further improve the function of various applications, it is preferable that the degree of crystallinity after recrystallization is 40% or more of that of the raw material zeolite, more preferably 45% or more, and particularly preferable 50% or more.

[0038] The yield after recrystallization treatment is preferably 85% or more of the yield before recrystallization treatment, and more preferably 90% or more, in terms of dry weight.

[0039] In the present invention, after the recrystallization process is completed, a separation process can be performed to separate the recrystallized fine zeolite from the alkaline solution. The separation method is not particularly limited, and filtration, centrifugation, etc., can be used. Washing may also be performed in the separation process, and a treatment to exchange the cations in the zeolite may be performed by a known method. In the present invention, it is preferable that the cations of the zeolite are protons. Furthermore, a calcination treatment may be performed after washing. The conditions for the calcination treatment can be appropriately determined according to the desired final form, but 400°C to 800°C is preferred, and 500°C to 700°C is more preferred. Furthermore, two or more calcination treatments can be provided by changing the temperature level, and a pre-calcination may be performed in the range of 100°C to 300°C to adjust the moisture content, followed by a main calcination at 400°C or higher. Furthermore, this calcination treatment does not have to be performed after the washing described above, but can be performed after any step in the manufacturing process of the catalyst of the present invention.

[0040] [Molding process] When using the zeolite obtained in this invention as a catalyst in a reaction, it may be used as is, or it may be modified by known methods such as silylation, specifically by the method described in Japanese Patent No. 6413823, and / or a molded product made by kneading with an inert substance and molding it may be used as a catalyst in the reaction. When decorating or molding zeolite, the zeolite usually becomes the active component of the catalyst, so when using the zeolite obtained in this invention as a catalyst, it is sometimes referred to as the "catalytically active component." When using molded zeolite, it is preferable to perform the firing at 400°C or higher after the molding process.

[0041] Substances or binders that are inert to the above reaction include alumina or alumina sol, silica, silica sol, quartz, clay minerals, and mixtures thereof.

[0042] In the present invention, the area-average diameter of the zeolite is preferably 0.6 μm or less. This area-average diameter refers to the area-average diameter of the zeolite before molding when the above molding treatment is performed, and refers to the area-average diameter of the zeolite corresponding to the above-mentioned zeolite before molding when the above molding treatment is not performed. The upper limit of the area-average diameter is preferably 0.6 μm or less, but preferably, in order, it is 0.5 μm or less, 0.49 μm or less, 0.45 μm or less, 0.40 μm or less, 0.35 μm or less, 0.34 μm or less, 0.33 μm or less, 0.32 μm or less, 0.31 μm or less, 0.30 μm or less, 0.29 μm or less, 0.28 μm or less, 0.27 μm or less, and most preferably 0.26 μm or less. The lower limit should be greater than 0, but preferably, in order, it is 0.01 μm or more, 0.05 μm or more, 0.10 μm or more, 0.15 μm or more, 0.20 μm or more, 0.21 μm or more, 0.22 μm or more, 0.23 μm or more, 0.24 μm or more, and most preferably 0.25 μm or more. Therefore, the preferred range for the area-average diameter is 0.01 μm or more and 0.6 μm or less, 0.01 μm or more and 0.5 μm or less, more preferably 0.01 μm or more and 0.49 μm or less, more preferably 0.05 μm or more and 0.45 μm or less, more preferably 0.05 μm or more and 0.40 μm or less, 0.05 μm or more and 0.35 μm or less, more preferably 0.05 μm or more and 0.34 μm or less, and more preferably 0.10 μm or more. The particle size is 0.33 μm or less, more preferably 0.15 μm to 0.32 μm, more preferably 0.20 μm to 0.31 μm, more preferably 0.21 μm to 0.30 μm, more preferably 0.22 μm to 0.29 μm, more preferably 0.23 μm to 0.28 μm, more preferably 0.24 μm to 0.27 μm, and most preferably 0.25 μm to 0.26 μm. The area-average diameter can be controlled by appropriately adjusting the particle size of the raw material subjected to the grinding process, the grinding conditions, and the recrystallization conditions.

[0043] [Method for producing propylene] The catalyst containing zeolite obtained by the manufacturing method of the present invention is suitable as a catalyst for producing propylene by contacting it with ethylene or ethanol as reaction raw materials. Propylene can be produced by known methods. Specifically, the methods described in Japanese Patent Application Publication No. 2007-291076 and International Publication No. 2010 / 128644 can be used. The reactor used may be a fixed-bed reactor, a moving-bed reactor, or a fluidized-bed reactor. When supplying the reaction materials to the reactor, it is preferable to mix them with a diluent gas before supplying them. The diluent gas is not particularly limited, but for example, nitrogen, helium, argon, and hydrogen can be used. There are no particular restrictions on the concentration of the reaction material gas supplied to the reactor, but 90 mol% or less is preferred. More preferably, it is 10 mol% to 80 mol%. If the concentration of the reaction material gas is too low, the reaction rate will be slow, requiring a large amount of catalyst to compensate or resulting in a high reaction temperature, which is undesirable. If the concentration of the reaction material gas is too high, the amount of by-products such as aromatic compounds will increase, and the yield of propylene tends to decrease. The supply rate of the reaction feedstock gas can be determined based on the activity of the catalyst used. The space velocity of ethylene GHSV0 is 1hr -1 from 1000hr -1 Preferably between 10 hours. -1 From 500hr -1 A range between these two ranges is even more preferable. The reaction temperature is not particularly limited as long as the reactants are efficiently and selectively converted to propylene, but for example, 200 to 600°C is preferred, and 300 to 500°C is particularly preferred. The conversion from reactants to propylene can be confirmed by analyzing the product gas by gas chromatography.

[0044] [Catalyst regeneration process] In this invention, a catalyst regeneration process may be performed when the conversion rate decreases. The regeneration method can be any known method that can remove the coke adhering to the catalyst, and there are no particular restrictions on the regeneration conditions. In a fixed-bed system, for example, a two-column swing system can be used to alternately perform the reaction and regeneration. In a fluidized-bed system, there are two methods: one in which the catalyst withdrawn from the reactor is regenerated and returned, and another in which a regenerator is installed alongside the reactor, and a portion of the catalyst is circulated between the reactor and the regenerator during regeneration. The gases used for regeneration are typically oxygen, hydrogen, air, or inert gases, which can be used as single gases or mixed gases, and are used to remove coke from the catalyst at temperatures between 400°C and 700°C. Of these gases, pure oxygen and / or pure hydrogen are preferred. The equipment used for regeneration is not particularly limited as long as it allows the gas used for regeneration and the catalyst to come into contact. Specifically, continuous fixed-bed regenerators, fluidized-bed regenerators, and mobile-bed regenerators are usually selected. A fluidized-bed regenerator is preferred. [Examples]

[0045] (Catalytic reaction conditions) A catalyst was packed into a stainless steel reactor with an inner diameter of 11.1 mm. The raw material gases were ethylene:nitrogen in a molar ratio of 1:2, and the space velocity of ethylene (GHSV0) was 227 hr. -1 The propylene was produced under the condition that the reaction temperature was 350°C. The generated gas was analyzed by gas chromatography, and the yield of propylene was calculated. The yield of propylene was calculated as the product of the conversion rate of ethylene and the selectivity of propylene. The conversion rate of ethylene was calculated as (moles of ethylene reacted / moles of ethylene supplied) × 100, and the selectivity of propylene was calculated as ((moles of propylene at the reactor outlet × 3) / Σ{(each product excluding ethylene at the reactor outlet) × (number of carbon atoms in each product)}) × 100. (Measurement of area-average diameter) The area-average diameter was calculated from the image processed according to the circularity measurement method (1). The area-average diameter was calculated from the area of ​​all particles in the image using the following formula (4). Here, area refers to the area of ​​the white portion of each particle, and the average value of the area of ​​all particles is the value obtained by dividing the area of ​​all particles in the image by the number of particles. (((Average area of ​​all particles) / π)^1 / 2)×2=(Area-average diameter) ···(4) (Measurement of SiO2 / Al2O3 molar ratio) The SiO2 / Al2O3 molar ratio was measured by SEM / EDS. Energy-dispersive X-ray analysis (EDS) was performed on a 26.9 μm square area of ​​dried granules for catalyst production or the catalyst itself using a scanning electron microscope (SEM) under conditions of an acceleration voltage of 15 kV and a magnification of 10,000x. There are no specific requirements for the preparation method of the sample used for imaging, but the granules are placed on a carbon tape, and then excess is removed using compressed air or the like. At that time, the amount of granules remaining on the carbon tape is set so that the area of ​​the granule portion accounts for 30% to 70% of the total image area when measured under the above SEM measurement conditions. Excluding elements other than Si, Al, O, and C, the molar ratio of Si to Al was calculated. The molar ratio here refers to the value obtained by expressing the molar amount of each element as a percentage of the sum of the molar amounts of Si, Al, O, and C. From the molar ratio of Si to Al, the SiO2 / Al2O3 molar ratio was calculated using the formula shown in (5) below. (Molar ratio of Si) / (Molar ratio of Al) × 2 = (Molar ratio of SiO2 / Al2O3) ... (5) (Measurement of crystallinity) The crystallinity of the zeolite after treatment was calculated based on the peak intensity in the XRD pattern of the zeolite before treatment. XRD was measured under the following conditions: CuKα source, voltage 40KV, current 30mA, scanning range 10~50°, scanning speed 10° / min, divergence slit 1 / 2°, divergence longitudinal limiting slit 10mm. The XRD chart is shown in Figure 1. The peak intensity referred to here is the signal intensity at 2θ = 20.8±0.3° where the signal intensity is maximum. The crystallinity was calculated using the formula shown in (6) below. As is well known to those skilled in the art, the pre-treatment and post-treatment data were normalized by the strongest peak in each chart after baseline correction and noise reduction. (Peak intensity of zeolite after treatment) / (Peak intensity of zeolite before treatment) = (Degree of crystallinity) ... (6)

[0046] [Example 1] (Catalyst manufacturing) SSZ-13 zeolite with an SiO2 / Al2O3 molar ratio of 11.9 and an area-average diameter of 0.492 μm was crushed to an area-average diameter of 0.256 μm and then recrystallized. The degree of crystallinity after recrystallization was 61% of that of the zeolite before crushing and recrystallization (Figure 1). This was designated as zeolite A. The circularity of this zeolite was 0.920. When a catalytic reaction was carried out using 1.0 g of the zeolite A obtained in the present invention, the ethylene conversion rate was 89.4% after 2 hours from the start of the reaction (Table 1, Figure 2). [Example 2] Zeolite B was obtained in the same manner as in Example 1, except that it was crushed and recrystallized so that the area-average diameter was 0.262 μm. The degree of crystallinity after recrystallization was 67% of that of the zeolite before crushing and recrystallization. When a catalytic reaction was carried out using 1.0 g of the obtained zeolite B of the present invention, the ethylene conversion rate after 2 hours from the start of the reaction was 81.1% (Table 1, Figure 2). The circularity of this zeolite was 0.916. [Example 3] When a catalytic reaction was carried out using SSZ-13 zeolite with an SiO2 / Al2O3 molar ratio of 11.9 and an area-average diameter of 0.492 μm as described in Example 1, the ethylene conversion rate after 2 hours from the start of the reaction was 40.6% (Table 1, Figure 2). The circularity of this zeolite was 0.903. [Example 4] Zeolite C was obtained in the same manner as in Example 1, except that it was crushed and recrystallized so that the area-average diameter was 0.172 μm. The degree of crystallinity after recrystallization was 57% of that of the zeolite before crushing and recrystallization. When a catalytic reaction was carried out using 1.0 g of the obtained zeolite C of the present invention, the ethylene conversion rate after 2 hours from the start of the reaction was 94.7% (Table 1, Figure 2). The circularity of this zeolite was 0.923. [Comparative Example 1] The SSZ-13 zeolite described in Example 1, with an SiO2 / Al2O3 molar ratio of 11.9 and an area-average diameter of 0.492 μm, was pulverized to obtain zeolite D. When a catalytic reaction was carried out using 1.0 g of the obtained zeolite D of the present invention, the ethylene conversion rate after 2 hours from the start of the reaction was 4.7%. The circularity of this zeolite was 0.877.

[0047] [Table 1] [Industrial applicability]

[0048] According to the present invention, propylene can be produced stably by gas-phase catalytic reaction using ethylene and / or ethanol as raw materials while maintaining catalytic performance. Therefore, propylene can be obtained with high efficiency using, for example, bioethanol, contributing to the effective industrial use of renewable energy.

Claims

1. In an SEM image taken using a scanning electron microscope (SEM) under conditions of an acceleration voltage of 25 kV and a magnification of 10,000x, where the area ratio of catalyst granules to the entire image is 30% to 70%, A catalyst having a zeolite in which the circularity of each particle, calculated from the area of ​​the portion corresponding to the zeolite particle in the image obtained by binarizing the SEM image and dividing the portion where two or more particles overlap, is 0.878 or higher. Here, circularity is calculated using the following formulas (1), (2), and (3) from the area and perimeter values ​​of each particle, and is the average of all particles captured in the image. Here, area refers to the area of ​​the part corresponding to the zeolite particle, and perimeter refers to the length of the outer circumference of the part corresponding to the zeolite particle. Equivalent diameter is the diameter of a perfect circle with the same area, and equivalent perimeter is the circumference of a perfect circle with the same area. (((Area) / π)^1 / 2) × 2 = (Equivalent diameter of a circle) ... (1) π * (equivalent diameter of a circle) = (equivalent circumference of a circle) ... (2) (Circularity) = (Equivalent circumference of a circle) / (Circumference) ... (3)

2. The catalyst according to claim 1, wherein the circularity is 0.916 or greater.

3. The catalyst is a CHA structure zeolite in which the zeolite has an area-average diameter greater than 0 and 0.3 μm or less, and is used in the production of propylene, as described in claim 1.

4. The catalyst according to any one of claims 1 to 3, wherein the zeolite is a phosphorus-free zeolite with a CHA structure.

5. The zeolite is SiO ２ / Al ２ O ３ The catalyst according to any one of claims 1 to 3, wherein the molar ratio is 1 or more and 100 or less.

6. The catalyst according to any one of claims 1 to 3, wherein the zeolite is SSZ-13 zeolite.

7. A catalyst according to any one of claims 1 to 3, which is formed by molding a zeolite.

8. A method for producing propylene using ethanol, ethylene, or a mixture of ethanol and ethylene as raw materials, and using the catalyst described in any one of claims 1 to 3.

9. A method for producing propylene according to claim 8, comprising a catalyst regeneration step.

10. The method for producing propylene according to claim 8, wherein the catalyst regeneration step is a regeneration step using either oxygen or hydrogen gas, or both.

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