METHOD FOR REGENERATING CATALYST AND METHOD FOR PRODUCING AROMATIC COMPOUND USING THE SAME

Abstract

To provide a method for efficiently regenerating a catalyst for aromatic compound production when producing an aromatic compound, and to provide a method for producing an aromatic compound capable of stably obtaining a high aromatic yield for a long period due to using the regenerating method as a step when producing an aromatic compound from a hydrocarbon raw material of aliphatic hydrocarbon and / or alicyclic hydrocarbon.SOLUTION: A method for regenerating a catalyst for aromatic compound production includes: controlling a contact temperature between 380-530°C so that when regenerating a catalyst for aromatic compound production by bringing regeneration gas containing 2-5 wt.% of oxygen into contact with the catalyst for aromatic compound production, having as the active ingredient, zeolite deteriorated in the performance due to coke adhesion, an oxygen concentration of exhaust gas after the contact becomes 0.5-1.5 wt.%; and mixing a part of the exhaust gas with air so as to bring an oxygen concentration to 2-5 wt.% and circularly supply it as regeneration gas.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for efficiently regenerating a catalyst for producing aromatic compounds used in the production of aromatic compounds, and also to a method for producing aromatic compounds from a hydrocarbon feedstock of aliphatic hydrocarbons and / or alicyclic hydrocarbons. In particular, the present invention relates to a method for producing aromatic compounds with excellent stability, which reduces the load on the catalyst by stably repeating catalytic reaction and regeneration by adding a regeneration step. [Background technology]

[0002] Aromatic compounds such as benzene, toluene, and xylene are often obtained by decomposing feedstock oil (e.g., naphtha) obtained by petroleum refining in a thermal cracking reactor, and separating and refining the obtained thermal cracking product by distillation or extraction. In these methods for producing aromatic compounds, aliphatic hydrocarbons (paraffinic, olefinic, acetylenic, and alicyclic hydrocarbons) are by-produced as thermal cracking products other than aromatic compounds. Therefore, since aliphatic hydrocarbons are simultaneously produced in conjunction with the production of aromatic compounds, the production amount of aromatic compounds is adjusted in accordance with the production amount of aliphatic hydrocarbons, which naturally limits the production amount.

[0003] It has been proposed to produce aromatic compounds by contacting an aliphatic or alicyclic hydrocarbon raw material with a catalyst mainly containing medium pore size zeolite at a temperature of about 400° C. to about 800° C. (See, for example, Patent Documents 1-2 and Non-Patent Documents 1-4.) Compared with the method of producing aromatic compounds by thermal decomposition, these production methods have the advantage that they have low added value and can produce aromatic compounds from surplus hydrocarbon raw materials.

[0004] A problem with the production of aromatic compounds using zeolite catalysts is the accumulation of carbonaceous matter on the zeolite catalyst during aromatization reactions, resulting in a decrease in activity, known as coking. To recover from the decrease in activity caused by this coking, a regeneration process is incorporated to burn off the carbonaceous matter, and reaction and regeneration are repeated alternately to continue operation of the actual equipment. Therefore, although the decrease in activity caused by coking results in an apparent decrease in activity, the activity can be reversibly restored by regeneration. However, if the catalyst is repeatedly subjected to a load such as excessive heat generation during the regeneration process, the catalytic activity will decrease irreversibly. Furthermore, since the regeneration process is an exothermic reaction, there is a possibility that the reactor will go into thermal runaway, damaging the reaction equipment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3741455 [Patent Document 2] Patent No. 3264447 [Non-patent literature]

[0006] [Non-Patent Document 1] Industrial & Engineering Chemistry Research, Vol. 31, p. 995 (1992) [Non-Patent Document 2] Industrial & Engineering Chemistry Research, Vol. 26, p. 647 (1987) [Non-Patent Document 3] Applied Catalysis Vol. 78, p. 15 (1991) [Non-Patent Document 4] Microporous and Mesoporous Materials, Vol. 47, p. 253 (2001) DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0007] The present invention provides a method for efficiently regenerating a catalyst for producing aromatic compounds when aromatic compounds are produced, and further provides a method for producing aromatic compounds with excellent stability, which stably repeats reaction and regeneration of the catalyst when producing aromatic compounds from a hydrocarbon feedstock such as an aliphatic hydrocarbon and / or an alicyclic hydrocarbon, thereby reducing the load on the catalyst. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors to solve the above problems, they discovered that when producing aromatic compounds from hydrocarbon compounds and burning off accumulated coke, controlling the oxygen concentration of the regeneration gas and circulating and reusing the exhaust gas enables safe and stable catalyst regeneration at low cost, resulting in a production method for efficiently producing aromatic compounds stably over a long period of time, and thus completed the present invention.

[0009] That is, the present invention relates to a method for regenerating a catalyst for aromatic compound production, which comprises contacting a catalyst for aromatic compound production having zeolite as an active component, the performance of which has been deteriorated due to coke adhesion, with a regeneration gas containing 2 to 5% by weight of oxygen to regenerate the catalyst, the contact temperature being controlled between 380 and 530°C so that the oxygen concentration of the exhaust gas after the contact is 0.5 to 1.5% by weight, and a part of the exhaust gas is mixed with air so that the oxygen concentration is 2 to 5% by weight, and the mixed gas is circulated and supplied as the regeneration gas.

[0010] The present invention will be described in detail below.

[0011] The method for regenerating a catalyst for aromatic compound production of the present invention is to contact a catalyst for aromatic compound production having zeolite as an active component whose performance has been deteriorated by coke adhesion with a regeneration gas containing 2 to 5% by weight of oxygen to regenerate the catalyst for aromatic compound production, and to control the contact temperature between 380 and 530°C so that the oxygen concentration of the exhaust gas after contact is 0.5 to 1.5% by weight, and to mix a part of the exhaust gas with air while controlling the oxygen concentration to 2 to 5% by weight, and to circulate and supply it again as a regeneration gas. By adopting such a regeneration method, it is possible to regenerate a catalyst for aromatic compound production stably, safely, and efficiently. The ratio of the exhaust gas to be mixed with air as the regeneration gas is arbitrary as long as it is possible to obtain a regeneration gas containing 2 to 5% by weight of oxygen, and it is particularly preferable to mix 75 to 98% by weight of the exhaust gas discharged as the exhaust gas.

[0012] (Catalyst for producing aromatic compounds) The catalyst for producing aromatic compounds in the present invention is one that contains zeolite as an active component. The zeolite is not particularly limited as long as it is one that falls within the category of zeolites, and is preferably a zeolite having a 10-membered ring skeleton structure, specifically, AEL, EUO, FER, MWW, HEU, MEL, MFI, NES, MRE, etc. In addition, since it is more excellent in reaction selectivity and productivity of aromatic compounds, it is preferably a zeolite containing MFI type, and more preferably, MFI type zeolite that satisfies the characteristics shown in (i) to (iv) below can be mentioned. In this case, MFI type refers to an aluminosilicate compound that belongs to the structure code MFI defined by the International Zeolite Society.

[0013] (i) The mesopore distribution curve has a peak, the half width (hw) of the peak is hw≦20 nm, the maximum value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is 0.05 ml / g≦pv. (ii) In powder X-ray diffraction measurement with a diffraction angle of 2θ, there is no peak in the range of 0.1 to 3 degrees. (iii) The average particle diameter (PD) is PD≦100 nm. (iv) Differential pore volume (dV P / d(d P )) - the micropore distribution curve has a maximum value and the most differential pore volume value (dV P / d(d P The pore diameters showing the largest values ​​of )) are in the range of 0.4 to 0.5 nm.

[0014] Here, the micropores are defined by IUPAC as pores with a pore diameter of 2 nm or less. The mesopores are defined by IUPAC as pores with a pore diameter of 2 to 50 nm. The micropores and mesopores can be measured by a general nitrogen adsorption method at liquid nitrogen temperature. By analyzing the measurement results obtained by the nitrogen adsorption method, the pore volume values ​​of the micropores and mesopores and the pore distribution curves can be obtained. For example, the following method can be used for the analysis.

[0015] For micropores, the adsorption process is analyzed using the Saito-Foley method (AIChE Journal, 1991, Vol. 37, pp. 429-436). For example, the total pore volume of the micropores can be obtained by integrating the amount of nitrogen gas desorbed in the range corresponding to a pore diameter of 2 nm or less. P (mL / g), the horizontal axis is the micropore diameter d P After obtaining a cumulative curve of the amount of nitrogen gas desorbed from the micropores (nm), the vertical axis represents the differential value (dV P / d(d P )) and the differential pore volume value (dV P / d(d P ))-Micropore distribution curves can be used to obtain the peak of the increase in nitrogen desorption amount per unit mass at the micropore diameter.

[0016] For mesopores, the desorption process is analyzed using the Barret-Joyner-Halenda method (Journal of the American Chemical Society, 1951, pp. 373-380). For example, the total pore volume of mesopores can be obtained by integrating the amount of nitrogen gas desorbed in the range corresponding to a pore diameter of 2 nm to 50 nm.

[0017] First, the vertical axis represents the amount of nitrogen desorption per unit mass, V P (mL / g), the horizontal axis is the mesopore diameter D P After obtaining a cumulative curve of the amount of nitrogen gas desorbed from the mesopores (nm), the vertical axis represents the differential value (d(V P ) / d(D P )), the peak of the increase in the amount of nitrogen desorbed per unit mass at the mesopore diameter can be obtained.

[0018] The PD can be calculated from the outer surface area using the following formula (1). PD=6 / S(1 / 2.29×10 6 +0.18×10 -6 ) (1) (Here, S is the external surface area (m 2 / g) In addition, the external surface area (S(m 2 The surface area (g) can be calculated by the t-plot method using a general nitrogen adsorption method at liquid nitrogen temperature. For example, when t is the thickness of the adsorption amount, the measurement points in the range of 0.6 to 1 nm are linearly approximated for t, and the external surface area is calculated from the slope of the regression line obtained.

[0019] Another method for measuring the particle size of zeolite is to randomly select 10 or more particles from a photograph taken with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and determine their surface area average diameter.

[0020] The MFI zeolite can be produced, for example, by dealuminating aluminum in the framework of MFI zeolite, which is a raw material that satisfies the above characteristics (i) to (iii), with steam or the like. The temperature of the steam treatment is, for example, preferably 400 to 900°C, particularly preferably 450 to 800°C, and more preferably 500 to 700°C. The partial pressure of the steam is preferably 0.001 to 5 MPa, particularly preferably 0.01 to 0.5 MPa, and more preferably 0.05 to 0.2 MPa. The concentration of the steam is preferably, for example, 0.01 to 100 vol% water vapor / dilution gas. The dilution gas may be an inert gas such as nitrogen, air, oxygen, carbon monoxide, carbon dioxide, or a mixture thereof. The steam treatment time can be selected arbitrarily. Furthermore, in order to enhance the effect of the steam treatment, it is preferable to perform ion exchange before and after the calcination treatment including the steam treatment.

[0021] As a method for producing MFI zeolite, which is a raw material that satisfies the above characteristics (i) to (iii), the following method can be mentioned, for example.

[0022] Amorphous aluminosilicate gel is added to an aqueous solution of tetrapropylammonium (hereinafter sometimes referred to as "TPA") hydroxide and sodium hydroxide to form a suspension, and MFI type zeolite is added to the resulting suspension as seed crystals to form a raw material composition. The resulting raw material composition is crystallized and calcined to obtain MFI type zeolite.

[0023] The form of the catalyst for producing aromatic compounds in the present invention is not limited, and the zeolite powder can be used in any form, for example, as a catalyst as it is, after compression molding to form a specific shape, or after mixing with a binder or the like and molding to form a specific shape.

[0024] (Regeneration of catalysts for aromatic compound production) The method for regenerating a catalyst for aromatic compound production of the present invention is to regenerate a catalyst for aromatic compound production whose performance has been reduced due to coke adhesion caused by, for example, producing aromatic compounds from hydrocarbons, and to regenerate the catalyst for aromatic compound production by contacting the catalyst for aromatic compound production to which coke has adhered with a regeneration gas containing 2-5% by weight of oxygen to regenerate the catalyst for aromatic compound production. The contact temperature is controlled between 380 and 530°C so that the oxygen concentration of the exhaust gas after contact is 0.5-1.5% by weight, and a part of the exhaust gas is mixed with air while controlling the oxygen concentration to be 2-5% by weight, and is circulated and supplied as a regeneration gas. At this time, the exhaust gas is mixed with air at the weight % calculated by formula (2), thereby making it possible to control the oxygen concentration to 2-5% by weight. (21 - regeneration gas oxygen concentration) / (21 - exhaust gas oxygen concentration) x 100 (2) Here, the regeneration gas used in regenerating the catalyst for producing aromatic compounds has an oxygen content of 2 to 5% by weight, and may be prepared by mixing air or oxygen with an inert gas such as nitrogen, argon, or neon. In this case, it is preferable to use a dry gas in order to suppress the reduction in the specific surface area of ​​the zeolite and the reduction in acid sites caused by the mixed water vapor and to eliminate the influence on the catalytic activity and catalyst life. The regeneration gas is further mixed with a part of the exhaust gas having an oxygen concentration of 0.5 to 1.5% by weight, and in this case, it is preferable to mix 75 to 98% by weight of the exhaust gas and prepare it. In addition, an inert gas may also be mixed when circulating and supplying.

[0025] The regeneration of the aromatic compound production catalyst of the present invention is performed by controlling the contact temperature between 380 and 530 ° C so that the oxygen concentration of the exhaust gas after contact with the regeneration gas is 0.5 to 1.5 wt%, and the contact temperature can be appropriately selected between 380 and 530 ° C as long as the oxygen concentration of the exhaust gas is within the range of 0.5 to 1.5 wt%. Here, if the oxygen content of the regeneration gas is less than 2 wt%, or if the oxygen content of the exhaust gas is more than 1.5 wt%, the coke removal efficiency is poor and it is difficult to recover the catalytic performance. In addition, if the oxygen content of the regeneration gas exceeds 5 wt%, or if the oxygen content of the exhaust gas is less than 0.5 wt%, coke combustion proceeds excessively, which may cause deterioration of the zeolite contained in the catalyst itself or damage to the reactor.

[0026] The supply amount and contact time of the regeneration gas when regenerating the catalyst for aromatic compound production are not particularly limited as long as the catalyst can be regenerated, and since it is possible to efficiently remove coke deposited on the catalyst for aromatic compound production, it is preferable to supply the regeneration gas at a volume ratio to the catalyst volume of 1:100 to 2000. In addition, the contact time is preferably 30 to 65 hours.

[0027] (Production of aromatic compounds) The method for regenerating a catalyst for aromatic compound production of the present invention can be directly applied to the regeneration of a catalyst whose performance has been deteriorated due to coke adhesion.Furthermore, as a more preferred embodiment, it can be applied to a production method in which the production of aromatic compounds by a catalyst for aromatic compound production and the regeneration of the catalyst are repeated, and specifically, it can be applied to a production method of aromatic compounds, which includes a step of contacting a catalyst for aromatic compound production having zeolite as an active component with aliphatic hydrocarbons and / or alicyclic hydrocarbons having a carbon number of 2 to 6 at a temperature range of 400°C to 800°C to produce aromatic compounds, and a regeneration method for the catalyst for aromatic compound production described above as a step.

[0028] The aliphatic and / or alicyclic hydrocarbons having 2 to 6 carbon atoms may be any that fall within the category, such as ethane, ethylene, propane, propylene, cyclopropane, n-butane, isobutane, 1-butene, 2-butene, isobutene, butadiene, cyclobutene, cyclobutane, n-pentane, 1-pentane, 2-pentane, 1-pentene, 2-pentene, 3-pentene, n-hexane, 1-hexane, 2-hexane, 1-hexene, 2-hexene, 3-hexene, hexadiene, cyclohexane, and mixtures thereof. In addition, petroleum, for example, C4 fraction, which is a distillation mixture of hydrocarbons having 4 carbon atoms obtained by cracking fractions of naphtha, C5 fraction, which is a distillation mixture of hydrocarbons having 5 carbon atoms, and C6 fraction, which is a distillation mixture of hydrocarbons having 6 carbon atoms, may also be mentioned.

[0029] The temperature range when aromatic compounds are produced by contacting with the aromatic compound production catalyst can be 400°C or more and 800°C or less, and is preferably 450°C or more and 650°C or less, since it is particularly excellent in production efficiency. The amount of raw material supplied to the aromatic compound production catalyst is preferably 1:50-2000 in terms of gas volume ratio, in order to achieve both production efficiency and aromatic yield, and is particularly preferably 1:100-1000. There is no restriction on the pressure during production, and it is preferable to carry out production at a pressure range of, for example, about 0.05 MPa to 5 MPa. When supplying raw materials, they can be used as single gases or mixed gases of the hydrocarbons, or as diluted single or mixed gases selected from inert gases such as nitrogen, hydrogen, carbon monoxide, and carbon dioxide.

[0030] The reaction type during production is not limited, and for example, not only a fixed bed, a transport bed, a fluidized bed, a moving bed, or a multi-tubular reactor, but also a continuous flow type, an intermittent flow type, a swing type reactor, etc. are usable. In particular, the reaction type using a swing type reactor is preferable because it is a particularly efficient method for producing aromatic compounds.

[0031] The aromatic compound produced is not particularly limited as long as it belongs to the category called aromatic compounds, and examples thereof include benzene, toluene, xylene, trimethylbenzene, ethylbenzene, propylbenzene, butylbenzene, naphthalene, methylnaphthalene, etc., and in particular, benzene, toluene, and xylene are preferred. Effect of the Invention

[0032] The present invention provides a method for efficiently regenerating a catalyst used in the production of aromatic compounds when aromatic compounds are produced, and also provides a method for producing aromatic compounds that can stably obtain a high aromatic yield over a long period of time by using the regeneration process as a step when producing aromatic compounds from hydrocarbon feedstocks such as aliphatic hydrocarbons and / or alicyclic hydrocarbons, and is therefore highly useful industrially as it has excellent productivity and stability. EXAMPLES

[0033] The present invention will be specifically described below with reference to examples.

[0034] The MFI type zeolite and the aromatic compound production catalyst used in the examples were measured and defined by the following methods.

[0035] ~Measurement of pore distribution, pore diameter, and external surface area~ The pore distribution and pore diameter of the zeolite were measured by nitrogen adsorption measurements.

[0036] A general nitrogen adsorption device (product name: BELSOAP-max, manufactured by BEL Japan) was used for the nitrogen adsorption measurements, and the adsorption side was measured at relative pressure (P / P0) intervals of 0.025. The desorption side was measured at relative pressure intervals of 0.05. The external surface area was calculated by linear approximation of the adsorption layer thickness range (t = 0.6-1.0 nm) using the t-plot method. BEL Japan's BELMaster (ver. 2.3.1) was used to analyze the pore distribution curve.

[0037] The adsorption process of the nitrogen adsorption measurement was analyzed by the Saito-Foley method (AIChE Journal, 1991, Vol. 37, pp. 429-436), and a micropore distribution curve was obtained, with the horizontal axis representing the constant of the micropore microdiameter and the vertical axis representing the differential value of the desorption amount of nitrogen gas.

[0038] The desorption process of the nitrogen adsorption measurement was analyzed by the Barret-Joyner-Halenda method (Journal of the American Chemical Society, 1951, pp. 373-380), and a mesopore distribution curve was obtained in which the horizontal axis is the pore diameter constant and the vertical axis is the differential value of the desorption amount of nitrogen gas. The total pore volume of mesopores was calculated by integrating the amount of desorption of nitrogen gas in the range of 2 nm to 50 nm.

[0039] The maximum peak of the differential value (d(V / m) / d(D)) of the amount of nitrogen gas desorbed from the mesopores with respect to the mesopore diameter value was analyzed using the intensity approximation of a Gaussian function, and mesopores with diameters within a range of twice the standard deviation (2σ) (=μ±2σ) from the center value (μ) of the Gaussian function were defined as uniform mesopores. The pore volume of uniform mesopores was calculated by integrating the amount of nitrogen gas desorbed within a range of ±2σ based on the center value (μ).

[0040] ~Measurement of average particle size~ The average particle size was calculated from the external surface area using the above formula (1). In formula (1), S is the external surface area (m 2 / g), and PD is the average particle diameter (m). 2 / g) was calculated from the t-plot method using the nitrogen adsorption method at liquid nitrogen temperature.

[0041] ~Measurement of SiO2 / Al2O3 molar ratio~ The SiO2 / Al2O3 molar ratio of the zeolite was determined by dissolving the MFI zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and measuring the resultant solution by inductively coupled plasma atomic emission spectrometry (ICP-AES) using a general ICP apparatus (product name OPTIMA3300DV, manufactured by PerkinElmer).

[0042] ~Measurement of aggregate size~ The aggregate diameter was determined by the dynamic scattering method using the volume average diameter (D 50 ) was measured. A Microtrac HRA (Model 9320-x100) (manufactured by Nikkiso) (trade name) was used for the measurement. In the measurement, the particle refractive index was 1.66, the particles were set to transparent non-spherical particles, and the liquid refractive index of the solvent was 1.33.

[0043] ~Powder X-ray diffraction measurement~ An X-ray diffraction measurement device (Spectris, product name: X'pert PRO MPD) was used, and measurements were taken in air using CuKα1 at a tube voltage of 45 kV and a tube current of 40 mA. The range of 0.04 to 5 degrees was analyzed at 0.08 degrees / step and 200 seconds / step. In addition, the background corrected for the absorption rate of the direct beam was removed.

[0044] The presence or absence of a peak can be confirmed visually, or a peak search program can be used. A common peak search program can be used. For example, when the measurement results, with the horizontal axis being 2θ (degrees) and the vertical axis being intensity (au), are smoothed using the SAVITSKY & GOLAY formula and a sliding polynomial filter, and then the second derivative is performed, if there are three or more consecutive negative values, it is determined that a peak exists.

[0045] ~Aromatic compound manufacturing equipment~ A fixed-bed gas-phase flow reactor using a stainless steel reaction tube (inner diameter 38 mm, length 4000 mm) was used. The reaction tube was filled with a catalyst for aromatic compound production, and after performing a heating pretreatment under a dry air flow, the raw material gas was fed to perform the aromatic compound production reaction. The reaction tube was insulated with a heat-insulating material, and the temperature was controlled by introducing a gas heated in a heating furnace. The reactor equipment conditions and operating conditions are not limited to the conditions described in this example, and can be appropriately selected. In the aromatic compound production process, the reaction outlet gas and reaction liquid were collected, and the gas components and liquid components were analyzed individually using a gas chromatograph. The gas components were analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, (trade name) GC-14B) equipped with a TCD detector. The packing material used was PorapakQ (trade name) manufactured by Waters or MS-5A (trade name) manufactured by GL Sciences. The liquid components were analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, (trade name) GC-2025) equipped with an FID detector. A capillary column (GL Sciences, product name: TC-1) was used as the separation column. In the aromatic compound production catalyst regeneration process, component analysis at the reactor outlet was constantly performed using a zirconia oxygen concentration meter (Yokogawa Electric, product name: ZS8) and a laser gas analyzer (Yokogawa Electric, product name: TDLS8000). A portion of the exhaust gas at the reactor outlet was circulated to the reactor inlet, and the regeneration gas flow rate and oxygen concentration were controlled by the mixture ratio of air, circulating gas, and nitrogen gas.

[0046] Preparation Example 1 (Preparation of raw zeolite) MFI type zeolite was produced by the method described in JP 2013-227203 A.

[0047] Amorphous aluminosilicate gel was added to an aqueous solution of tetrapropylammonium (hereinafter sometimes abbreviated as TPA) hydroxide and sodium hydroxide and suspended. MFI type zeolite was added as seed crystals to the resulting suspension to prepare a raw material composition. The amount of seed crystals added was 0.7% by weight based on the weight of Al2O3 and SiO2 in the raw material composition.

[0048] The composition of the raw material composition is as follows: SiO2 / Al2O3 molar ratio=48, TPA / Si molar ratio=0.05, Na / Si molar ratio=0.16, OH / Si molar ratio=0.21, H2O / Si molar ratio=10.

[0049] The obtained raw material composition was sealed in a stainless steel autoclave and crystallized for 4 days while stirring at 115°C to obtain a slurry-like mixed liquid. The crystallized slurry-like mixed liquid was subjected to solid-liquid separation using a centrifugal settler, and the solid particles were washed with a sufficient amount of pure water and dried at 110°C to obtain a dry powder. The obtained dry powder was dispersed in 1 mol / L hydrochloric acid, filtered, and dried. After calcination at 550°C for 1 hour in air, a calcination treatment including steam treatment at 600°C with 50% water vapor for 2 hours was performed. The obtained powder was dispersed in 1 mol / L hydrochloric acid, filtered, and washed to obtain MFI type zeolite.

[0050] The obtained MFI type zeolite had an average particle size of 38 nm, a SiO2 / Al2O3 molar ratio of 55, and a total pore volume of 0.45 ml / g. The micropore distribution curve had a maximum value with the largest differential pore volume value at a pore diameter of 0.4125 nm. The half-width of the peak of uniform mesopores in the mesopore distribution curve was 16 nm, and the center value was 15 nm. The pore volume of the uniform mesopores was 0.40 ml / g, and the ratio of the pore volume of the uniform mesopores to the total pore volume of the mesopores was 89%. In addition, the powder X-ray diffraction of the obtained MFI type zeolite showed no peak in the range of 0.1 to 3 degrees, indicating that the mesopores were irregularly connected.

[0051] Preparation Example 2 (Forming of raw zeolite) 100 parts by weight of the MFI zeolite obtained in Preparation Example 1 were mixed with 43 parts by weight of silica (Nissan Chemical Industries, (product name) Snowtex N-30G), 4 parts by weight of cellulose, and 30 parts by weight of pure water. The mixture was then formed into a cylindrical molded body having a diameter of 3.0 mm and a length of 2.0 to 5.5 mm (average length 4.5 mm). This was dried overnight at 100°C and then sintered at 600°C for 2 hours to prepare a catalyst for producing aromatic compounds.

[0052] Example 1 2.0 kg of the aromatic compound production catalyst obtained in Preparation Example 2 was filled into the aromatic compound production apparatus described above, and a mixed gas of butenes (1-butene 60% + trans-butene 15% + isobutene 15% + cis-butene 10%) was used as the aliphatic hydrocarbon raw material to produce aromatic compounds under the following conditions. After that, the catalyst for aromatic compound production on which coke had been attached was contacted with a regeneration gas in which air was diluted with nitrogen so that the oxygen concentration was 3% by weight, while controlling the temperature of the regeneration gas between 450 and 520°C so that the oxygen concentration of the exhaust gas (oxygen concentration at the reactor outlet) was 0.7 to 1.3%, and 80 to 95% by weight of the exhaust gas was mixed with air and circulated as a regeneration gas to maintain an oxygen concentration of 3% by weight, thereby regenerating the catalyst for aromatic compound production. The regeneration conditions for the catalyst for aromatic compound production are shown below. Then, the production of aromatic compounds and the regeneration of the catalyst for aromatic compound production were repeated, and the evaluation of the production of aromatic compounds was performed 10 times. The aromatics production catalyst, which had been repeatedly subjected to aromatic compound production and catalyst regeneration, showed stable butenes conversion, benzene yield, toluene yield, and xylene yield, and was capable of stable operation without thermal runaway during regeneration. The results are shown in Table 1.

[0053] (Aromatic compound production conditions) Reaction (catalysis) temperature: 570°C. Feed gas: butene mixed gas 3.0 kg / hour. Ratio of feed gas volume to catalyst volume: 1:480. Reaction time: 48 hours.

[0054] (Catalyst regeneration conditions for aromatic compound production) Playing temperature: 450℃~520℃. Regeneration gas oxygen concentration: 3% by weight. Reactor outlet oxygen concentration: 0.7-1.3 wt%. Ratio of regeneration gas volume to catalyst volume: 1:720. Pressure: 0.1MPaG. Play time: 35 hours.

[0055] [Table 1]

[0056] Example 2 Except for the aromatic compound production conditions and aromatic compound production catalyst regeneration conditions being as follows, the aromatic compound production and aromatic compound production catalyst regeneration were repeated 10 times in the same manner as in Example 1, and evaluation was performed. The aromatic compound production catalyst that had been repeatedly subjected to aromatic compound production and catalyst regeneration showed stable butenes conversion, benzene yield, toluene yield, and xylene yield, and no thermal runaway occurred during regeneration, allowing stable operation. The results are shown in Table 2.

[0057] (Aromatic compound production conditions) Reaction (catalysis) temperature: 585°C. Feed gas: butene mixed gas 4.0 kg / hour. Ratio of feed gas volume to catalyst volume: 1:650. Reaction time: 48 hours.

[0058] (Catalyst regeneration conditions for aromatic compound production) Playing temperature: 430℃~520℃. Regeneration gas oxygen concentration: 3% by weight. Reactor outlet oxygen concentration: 0.7-1.3 wt%. Ratio of regeneration gas volume to catalyst volume: 1:980. Pressure: 0.15MPaG. Playback time: 40 hours

[0059] [Table 2]

[0060] Example 3 Except for the aromatic compound production conditions and aromatic compound production catalyst regeneration conditions being as follows, the aromatic compound production and aromatic compound production catalyst regeneration were repeated 10 times in the same manner as in Example 1, and evaluation was performed. The aromatic compound production catalyst that had been repeatedly subjected to reaction and regeneration showed stable butenes conversion, benzene yield, toluene yield, and xylene yield, and stable operation was possible without thermal runaway during regeneration. The results are shown in Table 3.

[0061] (Aromatic compound production conditions) Reaction (catalysis) temperature: 600°C. Feed gas: butene mixed gas 2.0 kg / hour. Ratio of feed gas volume to catalyst volume: 1:310. Reaction time: 48 hours.

[0062] (Catalyst regeneration conditions for aromatic compound production) Playing temperature: 470℃~520℃. Regeneration gas oxygen concentration: 4.5% by weight. Reactor outlet oxygen concentration: 0.8-1.5 wt% Ratio of regeneration gas volume to catalyst volume: 1;470. Pressure: 0.2MPaG. Play time: 42 hours.

[0063] [Table 3]

[0064] Comparative Example 1 The production of aromatic compounds and the regeneration of the catalyst for producing aromatic compounds were repeated 10 times in the same manner as in Example 1, except that the oxygen concentration of the regeneration gas was set to 7% by weight, and evaluation was performed.

[0065] The butenes conversion rate began to decrease from the fifth cycle, and the total of the benzene yield, toluene yield, and xylene yield began to decrease clearly from the sixth cycle. The evaluation results are shown in Table 4.

[0066] [Table 4]

[0067] Comparative Example 2 The aromatic compound production and the regeneration of the catalyst for aromatic compound production were repeated 10 times in the same manner as in Example 1, except that the regeneration temperature was not controlled but was set to 550°C.

[0068] From the fourth cycle, the butenes conversion rate and the total yield of benzene, toluene and xylene began to decrease obviously. The evaluation results are shown in Table 5.

[0069] [Table 5]

[0070] Comparative Example 3 An attempt was made to repeatedly produce aromatic compounds and regenerate the catalyst for producing aromatic compounds in the same manner as in Example 2, except that the oxygen concentration in the regeneration gas was set to 1.5% by weight and the oxygen concentration at the reactor outlet was controlled to 0.5 to 1.0% by weight. However, coke removal was insufficient, and it was not possible to continue evaluating the production of aromatic compounds.

[0071] Comparative Example 4 An attempt was made to repeatedly produce aromatic compounds and regenerate the catalyst for producing aromatic compounds in the same manner as in Example 3, except that the oxygen concentration of the regeneration gas was set to 10% by weight and the oxygen concentration at the reactor outlet was controlled to 7.0 to 8.0% by weight. However, an issue occurred in which the temperature inside the reactor exceeded 650°C during regeneration, making stable regeneration impossible and making it impossible to evaluate the production of aromatic compounds. [Industrial Applicability]

[0072] The present invention provides a method for efficiently regenerating a catalyst for producing aromatic compounds when aromatic compounds are produced, and by using the regeneration method as a process when producing aromatic compounds from hydrocarbon raw materials such as aliphatic hydrocarbons and / or alicyclic hydrocarbons, the reaction and regeneration of the catalyst are repeated, thereby making the method industrially extremely useful, with excellent productivity, stability and safety.

Claims

1. A method for regenerating a catalyst for producing aromatic compounds, comprising contacting a catalyst for producing aromatic compounds having zeolite as an active ingredient, the performance of which has been reduced by the adhesion of coke, with a regeneration gas containing 2 to 5% by weight of oxygen to regenerate the catalyst, the method comprising controlling the contact temperature between 380 and 530°C so that the oxygen concentration of the exhaust gas after the contact is 0.5 to 1.5% by weight, and mixing 75 to 98% by weight of the exhaust gas with air so that the oxygen concentration is 2 to 5% by weight, and circulating and supplying the mixed gas as the regeneration gas.

2. 2. The method for regenerating a catalyst for aromatic compound production according to claim 1, wherein the zeolite is an MFI type zeolite.

3. 3. The method for regenerating a catalyst for aromatic compound production according to claim 1, wherein the zeolite is an MFI type zeolite that satisfies the following characteristics (i) to (iv): (i) The mesopore distribution curve has a peak, the half width (hw) of the peak is hw≦20 nm, the center value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is 0.05 ml / g≦pv. (ii) In powder X-ray diffraction measurement at a diffraction angle of 2θ, there is no peak in the range of 0.1 to 3 degrees. (iii) the average particle diameter (PD) is PD≦100 nm; (iv) Differential pore volume value (dV Ｐ / d(d Ｐ )) - the micropore distribution curve has a maximum value and the most differential pore volume value (dV Ｐ / d(d Ｐ The pore diameters showing the largest values ​​of (a) and (b) are in the range of 0.4 to 0.5 nm.

4. 4. The method for regenerating a catalyst for aromatic compound production according to claim 1, wherein the zeolite is one that has been subjected to a calcination treatment in which steam treatment is added during the calcination treatment in the production of the zeolite.

5. 5. The method for regenerating a catalyst for producing aromatic compounds according to any one of claims 1 to 4, characterized in that the regeneration gas is supplied to the catalyst for producing aromatic compounds in a volume ratio of 1:100 to 2000.

6. A method for producing aromatic compounds, comprising the steps of: producing aromatic compounds by contacting a catalyst for producing aromatic compounds having a zeolite as an active component with an aliphatic hydrocarbon and / or an alicyclic hydrocarbon having 2 to 6 carbon atoms at a temperature range of 400° C. or higher and 800° C. or lower; and regenerating the catalyst for producing aromatic compounds according to any one of claims 1 to 5.

7. The method for producing aromatic compounds according to claim 6, characterized in that the aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 6 carbon atoms is supplied to the catalyst for producing aromatic compounds in a volume ratio of 1:50 to 2000.

8. 8. The method for producing an aromatic compound according to claim 6, wherein the aromatic compound contains at least one of the group consisting of benzene, toluene, and xylene.

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