Process for producing aromatic hydrocarbons

Abstract

To provide a method for producing aromatic hydrocarbon in which, by producing a zeolite catalyst that is efficient and long-lasting and has a high selectivity for target product, an aromatic hydrocarbon having a high yield of BTX is produced from lower alkane or petroleum-derived raw material alkane containing the same.SOLUTION: By bringing a raw material composition containing alkane having 6 to 8 carbon atoms into contact with a zeolite catalyst having an MFI structure, a dehydrocyclization reaction is promoted to yield a cyclic unsaturated hydrocarbon. The zeolite catalyst uses a zeolite carrier that contains at least one metal atom selected from transition metal and post-transition metal in the zeolite skeleton and has Lewis acidity and strong solid basicity. The zeolite carrier carries platinum atom.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for dehydrogenating cyclizing lower alkanes using a catalyst to produce highly valuable aromatic hydrocarbons.

Background Art

[0002] The global market for polymer products such as synthetic rubber is expected to continue to expand in the future. On the other hand, looking at the global demand for oil, which is an important raw material in the chemical industry, the demand for oil as a fuel is sluggish, but the demand as a raw material for chemical products is on an increasing trend. Behind this is the idea that it is necessary to avoid consuming large amounts of precious resources such as oil for applications that can be replaced by raw materials such as coal (for example, power generation, etc.), and limit its use to applications with high added value that require oil (for example, raw materials for petrochemicals), that is, the noble use of oil is spreading. In the midst of the demand for the noble use of oil, the development of FCC / RFCC catalysts with high BTX yields and methods for producing BTX from biomass has become a major challenge.

[0003] Under such circumstances, technologies for producing 1,3-butadiene by the direct dehydrogenation reaction of n-butane described in Patent Document 1 have been proposed. In addition, as production technologies for aromatic compounds, in addition to the conventional production methods by hydrocracking using residual oil as a raw material and the production methods by hydrocracking using crude oil as a raw material, in recent years, the production of aromatic compounds from biomass has also attracted attention. For example, Patent Document 2 describes a method for converting paraffinic hydrocarbons having 6 to 8 carbon atoms into aromatic hydrocarbons, and Patent Document 3 describes a method for producing ethylbenzene from an 8-carbon fraction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, although the technique described in Patent Document 1 is useful for extracting hydrogen from linear compounds such as n-butane (dehydrogenation reaction), when synthesizing aromatic compounds with high added value, it is necessary to form carbon-carbon bonds (cyclization reaction). In the reaction described in Patent Document 1, the cyclization reaction could not be carried out. In the techniques described in Patent Document 2 and Patent Document 3, a catalyst composed of L-type zeolite (aluminosilicate), platinum, and halogen is used as the catalyst. However, at present, a satisfactory high-efficiency conversion catalyst has not been obtained.

[0006] By the way, for the catalyst used in the cyclization reaction, aluminum and gallium are mainly selected, platinum is not used, and zinc is designed to play an auxiliary role. With this catalyst, although aromatic compounds are indeed synthesized, a large amount of by-products are also generated, and in some cases, the amount of by-products generated is about the same as that of aromatic compounds. Therefore, it is required to develop a method for producing aromatic hydrocarbons that can efficiently and continuously produce a zeolite catalyst with a high selectivity for the target product from lower alkanes or petroleum-derived raw alkanes containing the same, in response to the increasing demand for BTX, which has become increasingly important in recent years.

Means for Solving the Problems

[0007] The inventors of the present invention have developed a catalyst useful for a selective aromatization reaction by arranging a transition metal or post-transition metal centered on zinc in the microspace of a zeolite carrier having an MFI structure and further supporting platinum on this zeolite carrier, enabling the control of the structure of the produced molecules.

[0008] The invention according to claim 1 is a method for producing aromatic hydrocarbons, comprising a dehydrogenation cyclization step of bringing a raw material composition containing an alkane having 6 to 8 carbon atoms into contact with a zeolite catalyst, wherein the zeolite catalyst has containing 1 to 15 atom% of Zn atoms relative to Si atoms and not containing Al atoms a zeolite support having an MFI structure and carrying platinum. and the zeolite carrier has Lewis acidity, and in the FT-IR analysis at room temperature of the zeolite carrier evacuated under vacuum at 450 °C for 1 hour, an absorption band derived from Zn-OH vibration is observed It is a method for producing aromatic hydrocarbons.

[0009] The invention according to claim 2 is the Zn the method for producing aromatic hydrocarbons according to claim 1, wherein the content of the atoms is 1 to 15 atom% with respect to the silicon atoms.

[0010] The invention according to claim 3 is the method for producing aromatic hydrocarbons according to claim 1 or claim 2, wherein the supported amount of the platinum is usually 0.05 to 2.5 wt% based on the total amount of the zeolite catalyst.

[0011] The invention according to claim 4 is the method for producing aromatic hydrocarbons according to any one of claims 1 to 3, wherein at least one of the alkanes is selected from n-hexane, n-heptane, n-octane, 1,2-dimethylcyclohexane, 1-octene, and 2-octene.

[0012] According to the present invention, by using a zeolite catalyst comprising a zeolite support having an MFI structure containing at least one metal atom selected from transition metals or post-transition metals in the zeolite framework and carrying platinum atoms for the production of aromatic hydrocarbons, aromatic hydrocarbons can be produced in a high yield.

[0013] Further, in the zeolite catalyst according to the present invention, there is almost no Bronsted acid, and only Lewis acid exists. Generally, it is known that the amount of by-products of the dehydrogenation reaction increases or decreases due to the presence of Bronsted acid. Since there is almost no Bronsted acid in the zeolite catalyst according to the present invention, side reactions can be controlled, and the generation of by-products can be suppressed. Therefore, by using the zeolite catalyst according to the present invention in the production of aromatic hydrocarbons, for example, side reactions can be suppressed, the selectivity of aromatic hydrocarbons can be improved, the generation of coke due to the polymerization of decomposition by-products can be suppressed, etc. Thus, aromatic hydrocarbons can be stably produced over a long period of time.

[0014] As the zeolite catalyst, one that has been subjected to a reduction treatment as a pretreatment may be used. The reduction treatment can be carried out, for example, by holding the zeolite catalyst at 400 to 600 °C in an atmosphere of a reducing gas. The holding time may be, for example, 0.5 to 5 hours. The reducing gas may contain, for example, hydrogen or the like. By using the zeolite catalyst that has been subjected to the reduction treatment, the initial induction period of the dehydrogenation reaction can be shortened. The initial induction period of the dehydrogenation reaction means a state in which very few of the supported metals in the zeolite catalyst are reduced to an active state and the activity of the catalyst is low.

[0015] Zeolites with an MFI structure are generally zeolites having thermal stability and acidic properties, but the zeolite support with an MFI structure according to the present invention has different acidic properties. That is, by introducing metal atoms such as zinc into the zeolite framework, a zeolite (the zeolite support in the present invention) having a basic structure with only Lewis acid present and exhibiting strong solid basicity can be obtained. Solid basicity means that the surface of the zeolite support exhibits basicity, and strong solid basicity means that the basicity of the surface of the zeolite support is strong.

[0016] Transition metals refer to metals belonging to Group 3 to Group 11 elements in the periodic table, and post-transition metals refer to base metals with atomic numbers later than those of transition metals in the 4th, 5th, and 6th periods of the periodic table. The metal atom may be a transition metal atom or a post-transition metal atom, but particularly, a zinc atom is preferable in terms of excellent reactivity in the dehydrogenation cyclization reaction of alkanes. The content of the metal atoms is 1 to 15 atom% relative to the Si atoms, and it is more preferable if it is within the range of 2 to 10 atom%. When the content of the metal atoms is less than 1 atom% relative to the Si atoms, the solid basicity of the zeolite support decreases, and the reactivity of the dehydrogenation cyclization reaction of alkanes is poor. Also, when the content of the metal atoms exceeds 15 atom% relative to the Si atoms, the number of metal atoms not introduced into the zeolite framework increases, and the reaction efficiency of the dehydrogenation cyclization reaction of alkanes with respect to the metal content decreases, which is not preferable. In addition to the metal atoms, other metal atoms such as copper, iron, nickel, tin, cobalt, indium, etc. may be included. Also, the content of the alkali metal contained in the zeolite support is preferably 1 atom% or less relative to the Si atoms. Although the crystallization of the zeolite is promoted when the alkali metal is added, if it exceeds 1 atom% relative to the Si atoms, the reactivity of the dehydrogenation cyclization reaction of alkanes is poor, which is not preferable. From the perspective of the reactivity of the dehydrogenation reaction of alkanes, the content of the alkali metal contained in the zeolite support is particularly preferably 0.1 atom% or less relative to the Si atoms. As the silica source, for example, hydrolyzable silicon compounds such as silicon alcoholate, silane, silicon tetrachloride, etc. can be used. The organic structure-directing agent is not particularly limited as long as a zeolite with an MFI structure can be obtained. For example, quaternary alkylammonium salts, amines, etc. can be used. The organic structure-directing agent may be used alone or in combination of two or more.

[0017] In the zeolite catalyst according to the present invention, platinum is supported on the zeolite carrier using a platinum (Pt) source. Examples of the platinum source include tetraammineplatinum (II) acid, tetraammineplatinum (II) acid salts (such as nitrates, etc.), tetraammineplatinum (II) acid hydroxide solution, dinitrodiammineplatinum (II) nitrate solution, hexahydroxoplatinum (IV) acid nitrate solution, hexahydroxoplatinum (IV) acid ethanolamine solution, and the like. As the platinum source, it is preferable to use a metal source that does not contain chlorine atoms. By using a metal source that does not contain chlorine atoms, corrosion of the device can be suppressed, and dehydrogenation of the raw material alkane can be carried out more efficiently. When platinum is supported on the zeolite carrier, the amount of platinum supported on the zeolite carrier is usually 0.05 to 2.5 wt%, preferably 0.1 to 2.0 wt% or less based on the total amount of the zeolite carrier. With such a supported amount, the platinum surface area per unit platinum weight increases, so that a more efficient reaction system can be realized. The method for supporting platinum on the zeolite carrier is not particularly limited, and for example, an impregnation method, a deposition method, a coprecipitation method, a kneading method, an ion exchange method, a pore filling method, etc. can be used.

[0018] The raw material composition only needs to contain at least a hydrocarbon compound having 6 to 8 carbon atoms. For example, it may contain n-hexane, n-heptane, n-octane, 2-methylheptane, 3-methylheptane, 1,2-dimethylcyclohexane, ethylcyclohexane, 1-octene, 2-octene, etc. As the raw material alkane, one of these may be used alone, or a mixture containing two or more may be used. The origin of the production of the raw material alkane is not particularly limited. For example, it may contain a C6 - C8 fraction mainly composed of hydrocarbons having 6 to 8 carbon atoms obtained from a naphtha pyrolysis furnace or the like. At this time, from the C6 - C8 fraction obtained from a naphtha pyrolysis furnace or a naphtha catalytic cracking furnace, a material in a state where compounds other than aromatic hydrocarbons resulting from the production method are arbitrarily mixed may be used as it is, or a purified one may be used. The feed composition may contain impurities other than the feed alkane, but it is preferable to increase the purity of the feed alkane because the activity is expected to decrease due to poisoning of platinum.

[0019] In the dehydrogenation cyclization step, for example, a reactor filled with a zeolite catalyst may be used, and the dehydrogenation cyclization reaction may be carried out by flowing the feed composition through the reactor. As the reactor, various reactors used for gas-phase reactions with solid catalysts can be used. Examples of the reactor include a fixed-bed adiabatic reactor, a radial flow reactor, a tubular reactor, and the like. The reaction mode of the dehydrogenation cyclization reaction may be, for example, a fixed-bed type, a moving-bed type, or a fluidized-bed type. Among these, the fixed-bed type is preferable from the viewpoint of equipment cost. The temperature at which the feed composition is brought into contact with the zeolite catalyst (which can also be referred to as the reaction temperature of the dehydrogenation cyclization reaction or the temperature in the reactor) may be, for example, 350 to 800°C from the viewpoint of reaction efficiency, preferably 400 to 700°C, and more preferably 450 to 650°C. If the reaction temperature is 350°C or higher, the equilibrium conversion rate of the feed alkane does not become too low, and thus the yield of aromatic hydrocarbons tends to further improve. If the reaction temperature is 800°C or lower, the coke formation rate is suppressed, and the high activity of the zeolite catalyst can be maintained for a longer period. Reaction conditions such as the pressure when the feed composition is brought into contact with the zeolite catalyst, the weight hourly space velocity (WHSV), the ratio of the feed rate of the raw material to the mass W of the zeolite catalyst (W / F), and the amounts of the raw material and the catalyst used may be designed according to the reaction apparatus, the activity of the catalyst, the reaction state, the physical properties of the raw material and the product, and the like. As described above, according to the production method of the present invention, by using a specific zeolite catalyst, aromatic hydrocarbons can be stably produced from a feed composition containing a feed alkane in a high yield over a long period of time. Thereby, the number of times of catalyst regeneration required for producing aromatic hydrocarbons can be reduced, and the production efficiency can be improved, which is very useful industrially.

Effects of the Invention

[0020] According to the present invention, by using a zeolite catalyst in which platinum atoms are supported on a zeolite support having an MFI structure containing at least one metal atom selected from transition metals or post-transition metals in a zeolite framework for the production of aromatic hydrocarbons, aromatic hydrocarbons can be stably produced from a raw material composition containing a raw material alkane in a high yield over a long period of time. As a result, the number of times of catalyst regeneration required for producing aromatic hydrocarbons can be reduced, and the production efficiency can be improved, which is very useful industrially.

[0021] In addition, the zeolite catalyst according to the present invention contains almost no Bronsted acid and only Lewis acid. Generally, it is known that the amount of by-products of dehydrogenation reaction increases or decreases due to the presence of Bronsted acid. Since the zeolite catalyst according to the present invention contains almost no Bronsted acid, side reactions can be controlled and the generation of by-products can be suppressed. Therefore, by using the zeolite catalyst according to the present invention for the production of aromatic hydrocarbons, for example, side reactions are suppressed and the selectivity of aromatic hydrocarbons is improved, and the generation of coke due to polymerization of decomposition by-products is suppressed, etc. can be considered, and thus aromatic hydrocarbons can be stably produced over a long period of time.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0023] Hereinafter, the manufacturing method of the present invention will be described in detail. However, the description of the constituent elements described below is an example as one embodiment of the present invention and is not limited to these contents.

[0024] [Preparation of Zeolite Carrier] The zeolite carrier according to this embodiment was prepared by combining and processing a silica gel aging step, a hydrothermal synthesis step, and a firing step. Here, zinc is used as the metal atom for explanation, but the same applies to the case of gallium. In the case of gallium, gallium nitrate n-hydrate was used as the introduction reagent. (1) Aging Step 4.0 g of tetraethyl orthosilicate (TEOS) and 4.6 g of 20-25 wt% tetrapropylammonium hydroxide aqueous solution (TPAOH, organic structure-directing agent) were added into a stainless steel pressure-resistant container, sealed, and stirred (aged) at 80°C for 24 hours. The state of the mixture after stirring was liquid. TPAOH is added as a structure-directing agent for constructing the zeolite structure and to make the aqueous solution basic. As a result, TEOS was polycondensed in the basic aqueous solution. (2) Hydrothermal Synthesis Step Zinc nitrate hexahydrate was dissolved in 0.5 g of ion-exchanged water. Subsequently, it was added to the mixture obtained in the (1) aging step and stirred until homogenized at room temperature (25 - 30 °C). As a result, a gel in which silica and zinc ions coexisted was obtained. The gelled mixture was put into an oven and hydrothermally synthesized at 175 °C for 24 hours while rotating at 20 rpm. (3) Firing step The mixture after the hydrothermal synthesis step was put into a centrifuge tube, and a gel-like sample was obtained by centrifugation. Then, this gel-like sample was washed with ion-exchanged water. For washing, ion-exchanged water was added to the gel-like sample for washing, followed by centrifugation. The pH of the supernatant after centrifugation was measured, and washing and centrifugation were repeated until the pH belonged to the range of 7 - 8. The washed gel-like sample was dried in an oven at 90 °C. The dried sample was put into a muffle furnace and fired at 550 °C for 8 hours in an air environment to obtain a zeolite support. As a result, the tetrapropylammonium ions (cations), which are organic substances in the zeolite, were removed.

[0025] The following measurements were performed on the zeolite support thus obtained. (a) Synchrotron XRD analysis XRD analysis was performed using a synchrotron XRD apparatus. As a result of the synchrotron XRD analysis (Figure 1), in the Zn-impregnated supported zeolite support (referring to a zeolite support in which Zn was impregnated and supported on an MFI-type zeolite without metal introduction), although peaks due to ZnO crystals were observed, no peaks derived from ZnO crystals were observed in the zeolite support in this example. (b) Solid-state NMR analysis 29Si CP-MAS NMR measurement was performed using NMR (manufactured by JEOL Ltd., ECA-600). When zeolite composed of Si, O, and Zn is measured by 29Si CP-MAS NMR, peaks appear at -110 to -120 ppm when all four bonds of Si atoms are -O-Si only, and peaks appear around -100 ppm when at least one of the four bonds of Si atoms is -O-Zn ("Synthesis and Characterization of Zincosilicates with the SOD Topology" M.A. Camblor, R.F.Lobe, H.Koller, M.E. Davis, Chemistry of materials, 6, P.2193-2199(1994)). In the zeolite carrier of this example, as shown in Figure 2, this peak at -100 ppm was observed. (c) FT-IR analysis Structural analysis was performed by FT-IR (FT / IR-4600 manufactured by JASCO Corporation). At this time, as a pretreatment, vacuum evacuation was performed at 450 °C for 1 hour. As shown in Figure 3, as a result of FT-IR analysis at room temperature after pretreatment by vacuum evacuation at 450 °C for 1 hour, an absorption band around 3640 cm -1 derived from the Zn-OH vibration of Zn was observed, and it was confirmed that Zn was incorporated into the zeolite framework and Zn atoms were isolated from each other. Also, after cooling to 150 °C after pretreatment, pyridine was introduced, and FT-IR analysis was performed after heating to 250 °C while evacuating. As a result (Figure 4), an absorption band derived from the vibration of C6H5N-H around 1560 cm -1 was not observed. On the other hand, for the absorption band around 1450 cm -1 which appears when Lewis acid is present, it could be confirmed in the zeolite carrier of this example. From this, it was found that the zeolite carrier in this example does not have Bronsted acid and has only Lewis acid. (d) CO2-TPD analysis CO2-TPD analysis was performed using a TPD analyzer (manufactured by MicrotracBEL Corp., BELCAT II). Approximately 30 mg of the zeolite support was pretreated at 500 °C for 1 hour while flowing helium gas at a flow rate of 50 mL / min. Thereafter, it was cooled to below 40 °C, and 1% CO2 / He gas was flowed at a flow rate of 50 mL / min to adsorb CO2 onto the zeolite support, and then helium gas was flowed at a flow rate of 50 mL / min for 5 minutes. Thereafter, while flowing helium gas at 30 mL / min, the temperature was raised to 800 °C at a rate of 10 °C / min, and the desorption of CO2 was analyzed using a TCD and a MASS. The MASS used was BELMass manufactured by MicrotracBEL Corp. The measurement of the base amount was calculated from the peak area by CO2-TPD. As a result of the CO2-TPD analysis (Figure 5), peaks were also observed in the vicinity of 100 °C and in the high-temperature region of 500 °C or higher, and it was confirmed that the solid basicity of this zeolite support was strong. The solid base amount calculated from the peak area in the high-temperature region of 500 °C or higher by CO2-TPD was 0 to 0.035 mmol / g. (e) NH3-TPD analysis NH3-TPD analysis was performed using a TPD analyzer (manufactured by MicrotracBEL Corp., BELCAT II). Approximately 30 mg of the zeolite support was pretreated at 500 °C for 1 hour while flowing helium gas at a flow rate of 50 mL / min. Thereafter, it was cooled to 100 °C, and 1% NH3 / He gas was flowed at a flow rate of 50 mL / min to adsorb NH3 onto the zeolite support, and then helium gas was flowed at a flow rate of 50 mL / min for 15 minutes. Thereafter, while flowing helium gas at 30 mL / min, the temperature was raised to 700 °C at a rate of 10 °C / min, and the desorption of NH3 was analyzed using a TCD and a MASS. The MASS used was BELMass manufactured by MicrotracBEL Corp. The measurement of the Lewis acid amount was calculated from the peak area by NH3-TPD. As a result of NH₃-TPD analysis (Figure 6), a large broad peak was observed from 150 °C to 500 °C. In the FT-IR analysis, it has been confirmed that the zeolite support in this example has no Bronsted acid and only Lewis acid. Therefore, this peak is considered to be derived from the desorption of NH₃ adsorbed on the Lewis acid. Also, the acid amount calculated from the peak area was 0.01 - 0.2 mmol / g.

[0026] [Loading of Platinum (Manufacture of Zeolite Catalyst)] Next, a method for loading platinum onto the zeolite support after the calcination step will be described. To 1 g of the calcined zeolite support, 0.22 g of a dinitrodiammine platinum nitrate solution with a platinum content of 4.557 wt% was added, and platinum ions were loaded by the impregnation method. Then, it was calcined in air at 550 °C for 8 hours to obtain a zeolite catalyst with platinum loaded on the zeolite support.

[0027] [Production of Aromatic Hydrocarbons] The production of aromatic hydrocarbons was carried out using a fixed-bed flow reactor (hereinafter referred to as the "reactor"). Specifically, 100 mg of the catalyst was charged into the reactor.

Example

[0028] (Production of Benzene Using n-Hexane as Raw Material) Under normal pressure and in an inert gas atmosphere, benzene was produced using n-hexane as the starting material. The catalyst used at this time was a support in which the metal atoms contained in the zeolite support were Zn atoms and the Si atom number / Zn atom number was adjusted to 10, and a zeolite catalyst with 1 wt% of platinum loaded on the support. Also, the mass of the catalyst / the flow rate of n-hexane (W / F) was 15.7 g·h·mol -1 , and the ratio of the catalyst mass to the n-hexane supply rate (i.e., the mass space velocity) was 5.5 h -1The supply amount of n - hexane was adjusted so as to achieve this. The reaction was carried out by distributing the reaction temperature at intervals of 50 °C from 450 to 600 °C. The obtained product was subjected to gas analysis using a gas chromatograph (GC - 2014 manufactured by Shimadzu Corporation). Table 1 shows the relationship between the temperature and the product composition when manufactured in this way. It became clear that benzene was obtained in a high yield.

[0029]

Table 1

[0030] In addition, the temperature was fixed at 600 °C, and the reaction was carried out by dividing the reaction time into intervals of 1 hour from 1 hour to 6 hours. The obtained product was subjected to gas analysis using a gas chromatograph (GC - 2014 manufactured by Shimadzu Corporation). Table 2 shows the relationship between the reaction time and the product composition when manufactured in this way.

[0031]

Table 2

Example

[0032] (Production of toluene using n - heptane as a raw material) Under normal pressure and in an inert gas atmosphere, toluene was produced using n - heptane as a starting material. The catalyst used at this time was a zeolite catalyst in which the metal atoms contained in the zeolite carrier were Zn atoms, the carrier was adjusted so that the number of Si atoms / number of Zn atoms was 10, and 1 wt% of platinum was supported on the carrier. Also, W / F was 17.4 g·h·mol -1 , and the supply amount of n - heptane was adjusted so that the mass space velocity was 5.7 h -1 . The reaction temperature was fixed at 600 °C, and the reaction was carried out by dividing the reaction time into intervals of 1 hour from 1 hour to 6 hours. The obtained product was subjected to gas analysis using a gas chromatograph (GC - 2014 manufactured by Shimadzu Corporation). Table 3 shows the relationship between the reaction time and the product composition when produced in this way. It was revealed that the yield of toluene was quite high, generally 40% or more.

[0033] [Table 3]

Example

[0034] (Production of xylene using n-octane as a raw material) Under normal pressure and in an inert gas atmosphere, xylene was produced using n-octane as the starting material. The catalyst used at this time was a zeolite catalyst in which the metal atoms contained in the zeolite support were Zn atoms, and the carrier was adjusted so that the number of Si atoms / number of Zn atoms was 10, and 1 wt% of platinum was supported on the carrier. Also, W / F was 19.3 g·h·mol -1 , and the supply rate of n-octane was adjusted so that the mass space velocity became 6 h -1 . The reaction temperature was fixed at 600 °C, and the production was carried out while dividing the reaction time from 1 hour to 5 hours at 1-hour intervals. The obtained product was subjected to gas analysis using a gas chromatograph (manufactured by Shimadzu Corporation, GC-2014). Table 4 shows the relationship between the reaction time and the product composition when produced in this way. It was revealed that the yield of o-xylene was higher than that of m-xylene and p-xylene.

[0035] [Table 4]

Example

[0036] Also, the reaction temperature was changed from 600 °C to 550 °C to produce xylene from n-octane. Other conditions were the same as in Example 3. Table 5 shows the relationship between the reaction time and the resulting composition when produced in this manner. Although the yield of o-xylene is higher than that of m-xylene and p-xylene, it was revealed that the yield decreases compared to the case of Example 3.

[0037]

Table 5

Example

[0038] (Production of Xylene Using n-Octane as a Raw Material) Under normal pressure and in an inert gas atmosphere, xylene was produced using n-octane as a starting material. The catalyst used at this time was a zeolite catalyst in which the metal atoms contained in the zeolite carrier were Ga atoms, and the carrier was adjusted so that the number of Si atoms / Ga atoms was 20, and 1 wt% of platinum was supported on the carrier. Also, W / F was 19.3 g·h·mol -1 , and the supply amount of n-octane was adjusted so that the mass space velocity became 6 h -1 . While fixing the reaction temperature at 600 °C, the production was carried out by dividing the reaction time from 1 hour to 6 hours every 1 hour. The obtained product was subjected to gas analysis using a gas chromatograph (GC-2014, manufactured by Shimadzu Corporation). Table 6 shows the relationship between the reaction time and the resulting composition when produced in this manner. Although the yield of o-xylene is higher than that of m-xylene and p-xylene, it was clearly shown that the yield decreases compared to Example 3.

[0039]

Table 6

[0040] As Comparative Example 1, under normal pressure and in an inert gas atmosphere, using n-octane as a starting material, xylene was produced. The catalyst used at this time was a zeolite catalyst in which the metal atoms contained in the zeolite carrier were Al atoms, and the carrier was adjusted so that the Si atom number / Al atom number was 12.5, and 1 wt% of platinum was supported on the carrier. Also, W / F was -1 19.3 g·h·mol -1 , and the supply amount of n-octane was adjusted so that the mass space velocity became 6 h . The reaction temperature was fixed at 600 °C, and the reaction time was divided into 1-hour intervals from 2 hours to 5 hours for production. The obtained product was subjected to gas analysis using a gas chromatograph (GC-2014, manufactured by Shimadzu Corporation).

[0041]

Table 7

[0042] As Comparative Example 2, under normal pressure and in an inert gas atmosphere, using n-octane as a starting material, xylene was produced. The catalyst used at this time was a zeolite catalyst in which the metal atoms contained in the zeolite carrier were Ni atoms, and the carrier was adjusted so that the Si atom number / Ni atom number was 10, and 1 wt% of platinum was supported on the carrier. Also, W / F was -1 19.3 g·h·mol -1 , and the supply amount of n-octane was adjusted so that the mass space velocity became 6 h Table 8 shows the relationship between the reaction time and the product composition when produced in this way. It was revealed that the yield decreased overwhelmingly compared to the case where the metal atom contained in the zeolite carrier was a zinc atom.

[0043]

Table 8

[0044] As Comparative Example 3, under normal pressure and in an inert gas atmosphere, using n-octane as the starting material, xylene was produced. The catalyst used at this time was a zeolite catalyst in which the metal atom contained in the zeolite carrier was a Co atom and the Si atom number / Co atom number was adjusted to 10, and 1 wt% of platinum was supported on the carrier. Also, W / F was 19.3 g·h·mol -1 , and the supply amount of n-octane was adjusted so that the mass space velocity became 6 h -1 . The reaction temperature was fixed at 550 °C, and the reaction time was divided into 1-hour intervals from 1 hour to 5 hours for production. The obtained product was subjected to gas analysis using a gas chromatograph (manufactured by Shimadzu Corporation, GC-2014). Table 9 shows the relationship between the reaction time and the product composition when produced in this way. It was revealed that the yield decreased overwhelmingly compared to the case where the metal atom contained in the zeolite carrier was a zinc atom.

[0045]

Table 9

[0046] As Comparative Example 4, under normal pressure and in an inert gas atmosphere, using n-octane as the starting material, xylene was produced. The catalyst used at this time was a zeolite catalyst in which 1 wt% of platinum was supported on a zeolite carrier containing no metal atom. Also, W / F was 19.3 g·h·mol -1 , and the mass space velocity was 6 h -1The supply amount of n-octane was adjusted so as to achieve this. While fixing the reaction temperature at 600 °C, the production was carried out by dividing the reaction time from 1 hour to 5 hours in 1-hour intervals. The obtained product was subjected to gas analysis using a gas chromatograph (GC-2014 manufactured by Shimadzu Corporation). Table 10 shows the relationship between the reaction time and the product composition when produced in this way. It became clear that the yield of xylene decreased overwhelmingly if there were no metal atoms in the zeolite carrier.

[0047]

Table 10

[0048] As Comparative Example 5, under normal pressure and in an inert gas atmosphere, using n-octane as the starting material, xylene was produced. The catalyst used at this time was a zeolite catalyst in which zinc and platinum were supported on a zeolite carrier containing no metal atoms. The supported amount of zinc was 10 wt%, and the supported amount of platinum was 1 wt%. Also, W / F was 19.3 g·h·mol -1 , and the mass space velocity was 6 h -1 The supply amount of n-octane was adjusted so as to achieve this. While fixing the reaction temperature at 600 °C, the production was carried out by dividing the reaction time from 1 hour to 5 hours in 1-hour intervals. The obtained product was subjected to gas analysis using a gas chromatograph (GC-2014 manufactured by Shimadzu Corporation). Table 11 shows the relationship between the reaction time and the product composition when produced in this way. It became clear that the yield of xylene decreased if the zeolite carrier did not contain metal atoms.

[0049]

Table 11

Examples

[0050] (Production of Aromatic Hydrocarbons from Various Hydrocarbon Compounds) Using n-octane, 2-methylheptane, 3-methylheptane, 1,2-dimethylcyclohexane, ethylcyclohexane, 1-octene, and 2-octene as starting materials, xylene was produced. The reaction conditions were the same as in Example 3. Table 12 shows the relationship between the starting materials and the product composition when produced in this way. It was revealed that the yield of xylene was extremely high when n-octane, 1,2-dimethylcyclohexane, 1-octene, and 2-octene were used as starting materials.

[0051]

Table 12

Claims

1. A method for producing aromatic hydrocarbons, comprising a dehydrogenation cyclization step of bringing a raw material composition containing an alkane having 6 to 8 carbon atoms into contact with a zeolite catalyst to obtain a cyclic unsaturated hydrocarbon, wherein the zeolite catalyst is a zeolite support having an MFI structure containing 1 to 15 atom% of Zn atoms relative to Si atoms and not containing Al atoms in the zeolite framework, on which platinum is supported, the zeolite support has Lewis acidity, and in the FT-IR analysis at room temperature of the zeolite support evacuated under vacuum at 450 °C for 1 hour, an absorption band derived from Zn-OH vibration is observed. A method for producing aromatic hydrocarbons.

2. The method for producing aromatic hydrocarbons according to Claim 1, wherein the content of the Zn atoms is 1 to 15 atom% relative to the silicon atoms.

3. The method for producing aromatic hydrocarbons according to Claim 1 or Claim 2, wherein the supported amount of the platinum is usually 0.05 to 2.5 wt% based on the total amount of the zeolite catalyst.

4. The method for producing aromatic hydrocarbons according to any one of Claims 1 to 3, wherein at least one of the alkanes is selected from n-hexane, n-heptane, n-octane, 1,2-dimethylcyclohexane, 1-octene, and 2-octene.

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