Ten-membered ring zeolite catalyst used for production of aromatic compound from raw material alcohol having 1 to 4 carbon atoms

Abstract

To provide a 10-membered ring zeolite catalyst with which aromatic compounds such as benzene, toluene, xylene, and the like can be produced from a raw material alcohol having 1 to 4 carbon atoms with high selectivity.SOLUTION: A 10-membered ring zeolite catalyst is obtained by a hydrothermal reaction of a raw material mixture containing water, a silicon source, an aluminum source, a hydroxide and a branched alcohol, in which the hydroxide is one or more selected from a group consisting of an alkali metal hydroxide and an alkaline earth metal hydroxide, and the branched alcohol has 5 or more carbon atoms and further has a quaternary carbon. The 10-membered ring zeolite catalyst is used for production of an aromatic compound from a raw material alcohol having 1 to 4 carbon atoms.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a 10-membered ring zeolite catalyst used for producing aromatic compounds from raw material alcohols having 1 to 4 carbon atoms. [Background technology]

[0002] Aromatic compounds such as benzene, toluene, and xylene are essential basic chemicals in the chemical industry. In recent years, as the climate change issue becomes more serious, there is an urgent need to develop manufacturing processes that use renewable resources instead of petroleum as raw materials for chemicals. In particular, alcohols such as ethanol derived from biomass have been attracting attention as renewable resources in recent years, and there is a demand for the establishment of new technologies to manufacture aromatic compounds using alcohol as a raw material. As a method for producing aromatic compounds using ethanol as a raw material, there have been proposed a production method using a catalyst in which crystalline aluminosilicate and crystalline gallosilicate are modified with silica (Patent Document 1), a production method using a fluidized bed catalyst containing phosphorus and zinc and a silica molded body consisting of MFI type zeolite and silica binder (Patent Document 2), and as a method for producing aromatic compounds from alcohol, a production method using a 10-membered ring pore zeolite with an average particle size of 100 nm or less, an outer surface Brønsted acid amount of 0.1 to 10.0 μmol / g and a silver content of 0.05 to 3 wt% (Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5294928 [Patent Document 2] Patent No. 6574059 [Patent Document 3] Patent Publication No. 2021-159884 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method proposed in the above Patent Document 1, multiple hydrothermal synthesis is required to cover the zeolite with silicate, and there is a problem with the cost of catalyst synthesis. In addition, in the method proposed in Patent Document 2, since a fluidized bed reactor is used, productivity is low due to material loss during circulation. Furthermore, in the method for producing aromatic compounds from methanol proposed in Patent Document 3, the particle size of the zeolite, the amount of Bronsted acid on the outer surface, and the content of the modifying metal Ag are controlled, and although the effect of improving the water resistance and catalyst life of the catalyst is verified, there is room for improvement in the selectivity of aromatic compounds, and in addition, the effect of controlling the catalyst function when ethanol is used as a raw material has not been confirmed. In both proposals, the effect of improving the selectivity of aromatic compounds by controlling the distribution of Al atoms in the zeolite as a catalyst used for producing aromatic compounds by ethanol conversion has not been verified, and there is still room for improvement.

[0005] An object of the present invention is to provide a 10-membered ring zeolite catalyst capable of producing aromatic compounds such as benzene, toluene, and xylene with high selectivity from a raw material alcohol having 1 to 4 carbon atoms. [Means for solving the problem]

[0006] The present invention provides the following [1] to

[10] . [1] A 10-membered ring zeolite catalyst obtained by hydrothermal reaction of a raw material mixture containing water, a silicon source, an aluminum source, a hydroxide, and a branched alcohol, wherein the hydroxide is at least one selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and the branched alcohol has 5 or more carbon atoms and has a quaternary carbon, and the 10-membered ring zeolite catalyst is used for producing an aromatic compound from a raw material alcohol having 1 to 4 carbon atoms. [2] The 10-membered ring zeolite catalyst according to [1], wherein the branched alcohol is a polyol having 5 to 10 carbon atoms. [3] The 10-membered ring zeolite catalyst according to [1] or [2], wherein a ratio of the silicon source to the aluminum source is 20.0 to 400.0:1 in terms of a molar ratio calculated as SiO2:Al2O3. [4] The 10-membered ring zeolite catalyst according to any one of [1] to [3], which has a pentasil structure. [5] The 10-membered ring zeolite catalyst according to any one of [1] to [4], which is an MFI type. [6] The 10-membered ring zeolite catalyst according to any one of [1] to [5], wherein the raw material alcohol is ethanol. [7] A method for producing the 10-membered ring zeolite catalyst according to any one of [1] to [6], comprising a step of hydrothermally reacting a raw material mixture containing the water, the silicon source, the aluminum source, the hydroxide, and the branched alcohol. [8] A method for producing an aromatic compound, comprising a reaction step of contacting the 10-membered ring zeolite catalyst according to any one of [1] to [6] with a raw material alcohol having 1 to 4 carbon atoms to obtain a product. [9] The method for producing an aromatic compound according to [8], wherein the reaction step is carried out under a temperature condition of 200° C. or higher and 600° C. or lower and a pressure condition of atmospheric pressure or higher and 1.0 MPa or lower.

[10] The method for producing an aromatic compound according to [8] or [9], wherein the selectivity of benzene, toluene and xylene in the product is 30 mass% or more calculated in terms of carbon atoms. Effect of the Invention

[0007] According to the present invention, it is possible to provide a 10-membered ring zeolite catalyst capable of producing aromatic compounds such as benzene, toluene, and xylene with high selectivity from a raw material alcohol having 1 to 4 carbon atoms. [Brief description of the drawings]

[0008] [Figure 1] 1 is an X-ray diffraction spectrum of the zeolite catalyst obtained in Example 1. [Diagram 2] 1 is an X-ray diffraction spectrum of the zeolite catalyst obtained in Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, the upper and lower limit values ​​of the numerical ranges of "greater than or equal to", "less than or equal to", and "to" are values ​​that can be combined arbitrarily, and the numerical values ​​of the examples can also be used as the upper and lower limit values. Furthermore, provisions that are considered to be preferable can be adopted arbitrarily. In other words, one provision that is considered to be preferable can be adopted in combination with one or more other provisions that are considered to be preferable. It can be said that a combination of preferable things is more preferable.

[0010] The present inventors have investigated zeolite catalysts for producing aromatic compounds from raw material alcohols, and have found that the selectivity of benzene, toluene, and xylene (BTX) contained in the resulting aromatic compounds is improved by using a branched alcohol having 5 or more carbon atoms and a quaternary carbon as a raw material for producing a 10-membered ring zeolite catalyst. The mechanism is described in detail below. Traditionally, the synthesis of 10-membered ring zeolites, more specifically the MFI-type aluminosilicate ZSM-5, has typically been carried out using the tetrapropylammonium cation (N(CH2CH2CH3)4 + , “TPA + " was used as an organic structure directing agent (filler), and Na + In contrast, the synthesis of the 10-membered ring zeolite catalyst of the present embodiment is carried out in the presence of a polyhydric alcohol having a structure of TPA. + This is similar to the reaction described above, but is carried out using uncharged branched alcohols such as pentaerythritol (C(CH2OH)4, "PET") in the presence of hydroxide. Here, 10-membered ring zeolites such as MFI type have a three-dimensional pore structure in which 10-membered ring linear pores (straight channels) and zigzag pores (zigzag channels) intersect with each other. The diameter of the 10-membered ring pores is about 5.5 Å, but the intersections of the pores are about 10 Å, forming a wide space. And because branched alcohols such as pentaerythritol molecules are bulky, they can only exist at the intersection. In this case, Al 3+The counter cations should be able to exist uniformly in the pores, but because the intersections are occupied by pentaerythritol molecules, the Al atoms can be selectively present in the straight channels or zigzag channels, other than at the intersections. Next, when the reaction proceeds at the intersection, successive reactions take place in a large reaction field, and it is thought that aromatic compounds that are bulkier than BTX are produced. On the other hand, the size of the 10-membered ring pores is just right for BTX to be produced in a shape-selective manner. In the 10-membered ring zeolite catalyst of this embodiment, the acid site positions are selectively arranged in the straight channels and zigzag channels of the 10-membered ring, and therefore the yield of BTX is improved.

[0011] (10-membered ring zeolite catalyst) As described above, the 10-membered ring zeolite catalyst of the present embodiment is obtained by hydrothermal reaction of a raw material mixture containing water, a silicon source, an aluminum source, a hydroxide, and a branched alcohol, wherein the hydroxide is one or more selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, the branched alcohol has 5 or more carbon atoms and a quaternary carbon, and is used for producing an aromatic compound from a raw material alcohol having 1 to 4 carbon atoms. Each component used in the raw material mixture will now be described.

[0012] The silicon source can be, for example, one or more selected from the group consisting of sodium silicate, colloidal silica, silica gel, fumed silica, silicates such as tetraalkyl orthosilicate and water glass, silicon alkoxides such as tetraethoxy orthosilicate and tetramethoxysilane, organic silicon compounds, and silicalite. As the aluminum source, for example, one or more selected from aluminum sulfate, aluminum nitrate, aluminum hydroxide, sodium aluminate, aluminum oxide, alumina sol, boehmite, and organic aluminum compounds can be used.

[0013] The ratio of the silicon source to the aluminum source, in terms of a molar ratio calculated as SiO2:Al2O3, is preferably 20.0 to 400.0: 1, more preferably 30.0 to 200.0: 1, and further preferably 35.0 to 150.0: 1. Here, the above-mentioned ratio calculated as SiO2:Al2O3 refers to the ratio when all silicon atoms in the silicon source are converted to SiO2, and all aluminum atoms in the aluminum source are converted to Al2O3.

[0014] The hydroxide is at least one selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, as described above. The alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Examples of the alkaline earth metal hydroxide include magnesium hydroxide and calcium hydroxide.

[0015] The amount of the alkali metal hydroxide and alkaline earth metal hydroxide used is preferably 0.01 to 5.0 mol, more preferably 0.05 to 2.0 mol, and even more preferably 0.07 to 0.80 mol, in terms of the total amount of the alkali metal hydroxide and alkaline earth metal hydroxide per 1 mol of silicon atoms in the raw material mixture.

[0016] The branched alcohol must have 5 or more carbon atoms and a quaternary carbon in order to function as a pore filler that fills the 10-membered ring channels, and is preferably a polyol having 5 to 10 carbon atoms, specifically pentaerythritol.

[0017] The amount of the branched alcohol used is preferably 0.05 to 10.0 mol, more preferably 0.1 to 5.0 mol, and even more preferably 0.2 to 2.0 mol, per mol of Si atoms in the raw material mixture.

[0018] The amount of water used is preferably 5.0 to 300 mol, more preferably 10 to 200 mol, and even more preferably 15 to 100 mol, per mol of silicon atom in the raw material mixture.

[0019] The zeolite catalyst of this embodiment must be a 10-membered ring zeolite catalyst, because the 10-membered ring provides a pore entrance size of just over 0.5 nm, which is just the right size for benzene, toluene, and paraxylene molecules to pass through. The 10-membered ring zeolite catalyst of this embodiment is not particularly limited as long as it contains a zeolite having a 10-membered ring skeleton structure, and as the zeolite having a 10-membered ring skeleton structure, AEL, EUO, FER, HEU, MEU, MEL, MFI, NES type, etc. are preferred from the viewpoints of reaction selectivity, productivity, etc., and further, since aromatic compounds can be efficiently produced when contacted with a raw material alcohol, it is preferred that it contains MEL or MFI type, and particularly preferred that it contains MFI type. And, for example, MFI type refers to an aluminosilicate compound belonging to the structure code MFI defined by the International Zeolite Society.

[0020] The 10-membered ring zeolite catalyst of this embodiment may be a metal-supported zeolite, and examples of the metal include zinc, gallium, nickel, iridium, palladium, rhodium, cobalt, platinum, europium, lanthanum, rhenium, ruthenium, silver, and gold. Furthermore, there are no limitations on the shape of the 10-membered ring zeolite catalyst of this embodiment, and the catalyst may have various shapes, such as a powder form as it is, a spherical form, a granular form, a cylindrical form, a circular cylinder form, a polygonal cylinder form, a polygonal column form, an elliptical form, or the like.

[0021] The 10-membered ring zeolite catalyst of this embodiment may be used together with a diluent. The diluent may be any material that falls within the category of known diluents, such as silica, silica-alumina, alumina, titania, carbon, ceramic-carbon, and the like. The 10-membered ring zeolite catalyst of this embodiment may be in a form molded together with the above-mentioned diluent, and the shape of the molded form is not limited, and the catalyst may have various shapes, such as a spherical shape, a granular shape, a cylindrical shape, a circular column shape, a polygonal tube shape, a polygonal column shape, an elliptical shape, etc.

[0022] (Method of producing 10-membered ring zeolite catalyst) As described above, the method for producing the 10-membered ring zeolite catalyst of the present embodiment includes a step of hydrothermally reacting a raw material mixture containing the water, the silicon source, the aluminum source, the hydroxide, and the branched alcohol. Specifically, the method for producing the 10-membered ring zeolite catalyst of the present invention preferably includes a raw material mixing step of mixing a silicon source, an aluminum source, a hydroxide, and a branched alcohol to obtain a raw material mixture, and a hydrothermal reaction step of subjecting the raw material mixture to a hydrothermal reaction.

[0023] (Hydrothermal reaction process) The temperature condition of the hydrothermal reaction step is preferably 100°C or higher, more preferably 120 to 250°C, and even more preferably 150 to 200°C. The reaction time of the hydrothermal reaction step is preferably from 3 to 500 hours, more preferably from 6 to 200 hours, and further preferably from 12 to 150 hours. The hydrothermal reaction step is preferably carried out under pressurized conditions by sealing the raw material mixture in a pressure-resistant vessel, and is preferably carried out while stirring the raw material mixture.

[0024] In the method for producing the 10-membered ring zeolite catalyst of this embodiment, it is preferable to further provide a step of subjecting the reaction product to solid-liquid separation, washing as necessary, and then calcining after the above hydrothermal reaction step.

[0025] The temperature condition for the firing step is preferably 300°C or higher, more preferably 400 to 800°C, and even more preferably 450 to 700°C. The firing time in the firing step is preferably 1 to 100 hours, more preferably 2 to 50 hours, and further preferably 5 to 24 hours.

[0026] (Production method of aromatic compounds) The method for producing an aromatic compound of this embodiment includes a reaction step of contacting the 10-membered ring zeolite catalyst with a raw material alcohol having 1 to 4 carbon atoms to obtain a product. The raw material alcohol having 1 to 4 carbon atoms is preferably ethanol.

[0027] The reaction type in the reaction step is not particularly limited, and can usually be selected from various processes such as a fixed bed, a moving bed, a boiling bed, and a suspension bed. A fixed bed is preferred because the reactor can be more easily designed and manufactured, and the operation can be more stably carried out. As a method for distributing the raw material alcohol, a gas phase distribution system in which the raw material alcohol is supplied in a gas phase is preferred.

[0028] The temperature condition in the reaction step is preferably from 200 to 600°C, more preferably from 300 to 580°C, and further preferably from 400 to 550°C. The pressure condition in the reaction step is preferably from atmospheric pressure to 2.0 MPa, more preferably from atmospheric pressure to 1.0 MPa. EXAMPLES

[0029] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0030] Example 1 (Production of Zeolite Catalyst) In a Teflon (registered trademark) beaker, 35.34 g of water, 1.03 g of sodium hydroxide, 6.81 g of PET, 1.50 g of aluminum nitrate nonahydrate, 15.0 g of colloidal silica, and 5% by mass of silicalite-1 (structural formula: Si 96 O 192 The resulting solution was added to a Teflon (registered trademark) inner cylinder and a stainless steel pressure vessel, and heated and stirred at 170° C. for 24 hours in a hydrothermal synthesis apparatus. The resulting turbid liquid was filtered, washed with water, dried at 80°C, and calcined in an electric furnace at 550°C for 10 hours. The resulting powder was heated and stirred twice in a 1M aqueous ammonium carbonate solution at 80°C for 3 hours, washed with water, dried at 80°C, and calcined in an electric furnace at 550°C for 10 hours to obtain a zeolite catalyst. The obtained zeolite catalyst was subjected to XRD diffraction measurement, and the results are shown in Figure 1.

[0031] (Production of aromatic compounds) A fixed-bed gas-phase flow reactor with a stainless steel reaction tube (inner diameter Φ4 mm, length 270 mm) was used. 100 mg of the zeolite catalyst synthesized as described above was packed in the middle of the stainless steel reaction tube, and a heat pretreatment was performed at 520°C for 1 hour under Ar flow. The catalyst layer was then heated using a ceramic tubular furnace, and while controlling the temperature at 500°C, raw material ethanol was pumped at a flow rate of 2.1 microliters / min to initiate the synthesis of aromatic compounds. The reaction outlet was connected to a gas chromatograph, and the products were analyzed online using a gas chromatograph (Shimadzu Corporation, product name: GC-2014) equipped with an FID detector and a capillary column (Agilent, product name: HP-PLOT Q) as a separation column. As a result, the total carbon atom content of benzene, toluene and xylene based on the total carbon atoms in the product was 32.0 mass %. In addition, the conversion rate of the raw material ethanol was 100 mass %.

[0032] Comparative Example 1 (Production of Zeolite Catalyst) In a Teflon (registered trademark) beaker, 30.2 g of water, 0.50 g of aluminum nitrate nonahydrate, 0.49 g of sodium chloride, 4.24 g of tetrapropylammonium hydroxide (above "TPA"), and 5.02 g of colloidal silica were added in that order so that the molar ratio of SiO2:Al2O3:TPA2O:Na2O:H2O was 1:0.02:0.25:0.125:60, and the mixture was stirred at 80°C for 24 hours. The resulting solution was added to a Teflon (registered trademark) inner cylinder and a stainless steel pressure-resistant container, and heated and stirred at 170°C for 72 hours in a hydrothermal synthesis apparatus. The resulting turbid liquid was filtered, washed with water, dried at 80°C, and finally fired in an electric furnace at 550°C for 10 hours. The obtained zeolite catalyst was subjected to XRD diffraction measurement, and the results are shown in Figure 2.

[0033] (Production of aromatic compounds) An aromatic compound was produced in the same manner as in Example 1 using the zeolite catalyst synthesized as described above. As a result, the total carbon atom content of benzene, toluene and xylene based on the total carbon atoms in the product was 25.2 mass %. Also, the conversion rate of the raw material ethanol was 100 mass %. [Industrial Applicability]

[0034] The 10-membered ring zeolite catalyst of the present embodiment can produce aromatic compounds from raw material alcohols, and has excellent selectivity for benzene, toluene, and xylene, which are useful as basic chemicals, and is therefore suitable for use in the production of aromatic compounds.

Claims

1. The 10-membered ring zeolite catalyst is obtained by hydrothermal reaction of a raw material mixture containing water, a silicon source, an aluminum source, a hydroxide, and a branched alcohol, wherein the hydroxide is one or more selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and the branched alcohol has 5 or more carbon atoms and has a quaternary carbon, and the 10-membered ring zeolite catalyst is used for producing an aromatic compound from a raw material alcohol having 1 to 4 carbon atoms.

2. 2. The 10-membered ring zeolite catalyst according to claim 1, wherein the branched alcohol is a polyol having 5 to 10 carbon atoms.

3. The ratio of the silicon source to the aluminum source is SiO ２ :Al ２ O ３ The 10-membered ring zeolite catalyst according to claim 1, wherein the molar ratio of the 10-membered ring zeolite catalyst is 20.0 to 400.0:

1.

4. The 10-membered ring zeolite catalyst according to claim 1 having a pentasil structure.

5. 2. The 10-membered ring zeolite catalyst according to claim 1, which is an MFI type.

6. 2. The 10-membered ring zeolite catalyst according to claim 1, wherein the raw material alcohol is ethanol.

7. 2. The method for producing the 10-membered ring zeolite catalyst according to claim 1, comprising a step of hydrothermally reacting a raw material mixture containing the water, the silicon source, the aluminum source, the hydroxide, and the branched alcohol.

8. A method for producing an aromatic compound, comprising a reaction step of contacting the 10-membered ring zeolite catalyst according to claim 1 with a raw material alcohol having 1 to 4 carbon atoms to obtain a product.

9. The method for producing an aromatic compound according to claim 8, wherein the reaction step is carried out under a temperature condition of 200° C. or more and 600° C. or less and a pressure condition of atmospheric pressure or more and 1.0 MPa or less.

10. The method for producing an aromatic compound according to claim 8, wherein the selectivity of benzene, toluene and xylene in the product is 30 mass% or more calculated in terms of carbon atoms.

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