Method and system for producing 2, 6-dimethylnaphthalene through isomerization reaction in moving bed reactor

Abstract

The invention relates to a method and system for producing 2, 6-dimethylnaphthalene through isomerization reaction in a moving bed reactor, and the method comprises the following steps: contacting dimethylnaphthalene raw oil with an isomerization catalyst in the moving bed reactor, and carrying out isomerization reaction to obtain an oil-gas mixture and a spent catalyst; and separating the oil-gas mixture to obtain the 2, 6-dimethylnaphthalene. The spent catalyst enters a catalyst hopper system to remove gas, and then enters a catalyst regenerator to be regenerated; enabling the regenerated catalyst to enter a catalyst hopper system to remove gas, and then returning to the moving bed reactor. According to the invention, the dimethylnaphthalene raw oil is contacted with the isomerization catalyst in the moving bed reactor for isomerization reaction, the deactivated catalyst is subjected to gas removal and regeneration, and the regenerated catalyst is returned to the moving bed reactor for recycling after gas removal, so that high-efficiency and continuous production of 2, 6-dimethylnaphthalene is realized.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a method and system for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor. Background Art

[0002] 2,6-Dimethylnaphthalene (2,6-DMN) is an important organic chemical raw material. Its oxide 2,6-naphthalene dicarboxylic acid reacts with ethylene glycol to produce a new high-performance polyester material polyethylene 2,6-naphthalate (PEN). PEN has excellent heat resistance, mechanical properties, gas barrier properties, chemical stability and radiation resistance, and has a very broad application prospect. At present, the production cost of 2,6-DMN is the key factor restricting the market size of PEN.

[0003] Amoco Oil Company was the first to realize the large-scale production of 2,6-DMN, using o-xylene and butadiene to produce 2,6-DMN through alkylation, cyclization, dehydrogenation, separation and isomerization. Samleng Gas Chemical Company also explored many process routes, but ultimately used the synthesis method of o-xylene and butadiene. Unlike the process of Amoco Oil Company, the cyclization and dehydrogenation of this method are carried out simultaneously in the gas phase.

[0004] ExxonMobil and Kobe Steel have developed a 2,6-DMN production process using 2-methylnaphthalene and 1-methylnaphthalene as raw materials. The process has the advantages of simple reaction process, no cyclization, mild conditions and low raw materials. However, other DMNs will be produced in the process of producing 2,6-DMN by methylation, and it is necessary to select a suitable method for isomerization to further improve the selectivity of 2,6-DMN products. DMNs can be divided into three groups and an additional single isomer. The isomers within the group are easier to isomerize with each other, while the isomerization reaction between groups is more difficult to occur. The conversion within the 2,6-traid group is the main process for isomerization production of 2,6-DMN, mainly the conversion between 1,5-DMN, 1,6-DMN and 2,6-DMN. The reaction is controlled by thermodynamics. When the reaction is close to equilibrium under controlled conditions, the yield of 2,6-DMN can only reach 48%. Samleng Gas Chemical Company's patent US5495060A uses 1,6-DMN as raw material and mordenite as catalyst to produce 2,6-DMN by liquid phase isomerization at a fixed bed temperature not exceeding 250°C. Hyosung Company's patent EP1870391A1 reports a method for producing 2,5-DMN from 1,5-DMN. The process uses H-type β molecular sieve as a catalyst to carry out isomerization reaction in a fixed bed reactor, with a reaction temperature of 250-320°C and a reaction space velocity of 2-4h -1Under the optimal reaction conditions, the content of 2,6-DMN in the products of the two methods can reach more than 40%. However, both 1,5-DMN and 1,6-DMN belong to the 2,6-traid intergroup raw materials and are difficult to apply in actual production.

[0005] The production of 2,6-DMN from naphthalene derivatives often requires the use of some expensive chemical reagents as catalysts or solvents in the reaction process, which directly leads to a decrease in economic value. Catalytic cracking diesel / light cycle oil (LCO) is one of the by-products of the catalytic cracking gasoline production process. It contains a large amount of high-value polycyclic aromatic hydrocarbons, such as naphthalene, methylnaphthalene, dimethylnaphthalene, phenanthrene, anthracene, etc., with a content of up to 80% by weight. Isomerization of dimethylnaphthalene in LCO to produce 2,6-DMN has good prospects. Patents US6018087A and US6011190A report a method for isomerizing 2,6-DMN from DMNs, using MCM-22 catalyst, the reactor is a fixed bed reactor, and the content of 2,6-DMN in the product is increased. The difference between the two methods is that the reaction temperature of the former is lower, belonging to liquid phase isomerization, and the reaction temperature of the latter is higher, belonging to gas phase isomerization.

[0006] In addition to the two processes of gas phase isomerization and liquid phase isomerization, Chevron's patent US6015930A uses a hydroisomerization method to produce 2,6-DMN. The mixed raw materials of 2,7-DMN and xylene are first hydroisomerized at low temperature and high pressure, and then dehydrogenated at high temperature and low pressure. The yield of 2,6-DMN is more than 25%. UOP's patent US4777312A also reports a method of hydroisomerization, which increases the content of 2,6-DMN in the product by introducing hydrogen during the isomerization reaction.

[0007] The isomerization reaction rate of dimethylnaphthalene is relatively slow. In the above patent report, a fixed bed reactor is used to carry out gas phase or liquid phase reaction in the presence of hydrogen or non-hydrogen atmosphere, while the regeneration of the coked catalyst needs to be carried out in a high temperature oxygen-rich atmosphere. Conventional fixed bed devices cannot meet the requirements of different gas atmospheres for reaction and regeneration, which is not conducive to the continuous production of 2,6-DMN. In addition, the fixed bed catalyst has poor thermal conductivity, and the gas flow rate is greatly limited by the pressure drop, resulting in poor heat transfer performance of the bed and difficulty in controlling the temperature.

[0008] Therefore, how to stably and continuously isomerize the LCO aromatics-rich fraction to produce 2,6-DMN is a technical problem that needs to be solved urgently. Summary of the invention

[0009] The invention provides a method and system for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, the purpose of which is to make dimethylnaphthalene raw oil undergo isomerization reaction in a moving bed reactor to efficiently and continuously produce high-value 2,6-dimethylnaphthalene products.

[0010] On the one hand, the present invention relates to a method for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, the method comprising: contacting dimethylnaphthalene feedstock oil with an isomerization catalyst in a moving bed reactor and performing an isomerization reaction to obtain an oil-gas mixture and a catalyst to be regenerated; separating the oil-gas mixture to obtain 2,6-dimethylnaphthalene; allowing the catalyst to be regenerated to enter a catalyst hopper system to remove gas, and then enter a catalyst regenerator for regeneration to obtain a regenerated catalyst; allowing the regenerated catalyst to enter a catalyst hopper system to remove gas, and then return it to the moving bed reactor.

[0011] Optionally, the dimethylnaphthalene feedstock oil is a dimethylnaphthalene isomer mixture and / or dimethylnaphthalene-rich hydrocarbon oil; the dimethylnaphthalene-rich hydrocarbon oil is selected from a combination of one or more of catalytic cracking light cycle oil, coal tar, medium wash oil and ethylene tar; and / or the dimethylnaphthalene content in the dimethylnaphthalene-rich hydrocarbon oil is not less than 20 weight %.

[0012] Optionally, the isomerization catalyst comprises an active component and a carrier, the active component comprises a zeolite molecular sieve, the carrier comprises a combination of one or more of alumina, silica and clay; the zeolite molecular sieve is a medium-pore zeolite and / or a large-pore zeolite; and / or, the zeolite molecular sieve is a combination of one or more of ZSM molecular sieve, MCM molecular sieve, Beta molecular sieve and mordenite molecular sieve; and / or, the content of the active component in the isomerization catalyst is 20 to 90 weight %; and / or, the isomerization catalyst is a spherical catalyst with a diameter of 0.3 to 5 mm.

[0013] Optionally, the isomerization catalyst comprises the following components based on the mass of the catalyst: 65-85% of a zeolite molecular sieve, 5-30% of a carrier and 5-30% of a binder, wherein the zeolite molecular sieve contains 0.1-2.0 wt% of a phosphorus compound calculated as P2O5 and 0.1-2.0 wt% of a rare earth compound calculated as RE2O3.

[0014] Optionally, the zeolite molecular sieve is mordenite or H-type mordenite; the rare earth is selected from one or more of lanthanum, cerium, neodymium, and praseodymium, preferably lanthanum and cerium; the carrier is clay, selected from one or more of pseudo-boehmite, kaolin, halloysite, montmorillonite, diatomaceous earth, hydrotalcite and bentonite, preferably kaolin or halloysite; the binder is selected from one or more of silica sol, aluminum sol, silica aluminum sol or phosphate aluminum sol, preferably silica sol.

[0015] Optionally, the isomerization reaction conditions include: the reaction atmosphere is hydrogen and / or nitrogen, the reaction temperature is 250-450° C., the reaction pressure is 0.1-1.0 MPa, the weight hourly space velocity of the dimethylnaphthalene feedstock oil is 0.01-5 h -1 , the volume ratio of hydrogen to oil is 100-200.

[0016] Optionally, the regeneration conditions include: carrying out in an oxygen-containing atmosphere, a temperature of 450-560° C., and a pressure of 0.1-1.0 MPa.

[0017] Optionally, separating the oil-gas mixture comprises the following steps: (1) separating the oil-gas mixture into a gas product and a mixed oil product; (2) fractionating the mixed oil product into gasoline, diesel and circulating oil; and (3) separating and purifying the diesel to obtain 2,6-dimethylnaphthalene and residual diesel.

[0018] Optionally, the method further includes the following step after separating the oil-gas mixture: returning the circulating oil and the remaining diesel to the moving bed reactor to contact with the isomerization catalyst and perform an isomerization reaction; and / or, the method further includes the following step before performing oil-gas separation on the oil-gas mixture: filtering the oil-gas mixture.

[0019] On the other hand, the present invention relates to a system for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, the system comprising a moving bed reactor, a separation system, a catalyst hopper system and a catalyst regenerator; the moving bed reactor comprises, from bottom to top, an inlet section, a reaction section and an outlet section; the inlet section is provided with a dimethylnaphthalene feedstock oil inlet, and the upper portion of the reaction section is provided with a catalyst inlet; the outlet section is provided with an oil and gas outlet, which is communicated with the oil and gas inlet of the separation system, and the separation system is provided with a 2,6-dimethylnaphthalene outlet; the lower portion of the reaction section is provided with an outlet for catalyst to be regenerated, which is communicated with an inlet of catalyst to be regenerated of the catalyst hopper system, which is communicated with an inlet of catalyst to be regenerated of the catalyst hopper system, which is communicated with an inlet of catalyst to be regenerated of the catalyst regenerator; the regenerated catalyst outlet of the catalyst regenerator is communicated with the regenerated catalyst inlet of the catalyst hopper system, which is communicated with the catalyst inlet of the catalyst hopper system.

[0020] Optionally, the separation system includes an oil-gas separation system, a distillation system and a separation and purification system; the oil and gas outlet of the outlet section is connected to the oil and gas inlet of the oil-gas separation system; the oil-gas separation system is provided with a gas product outlet and a mixed oil product outlet, and the mixed oil product outlet is connected to the inlet of the distillation system; the distillation system is provided with a gasoline outlet, a diesel outlet and a circulating oil outlet; the diesel outlet is connected to the inlet of the separation and purification system, and the separation and purification system is provided with a residual diesel outlet and the 2,6-dimethylnaphthalene outlet.

[0021] Optionally, the inlet section is provided with a recycled oil inlet, and the circulating oil outlet and the residual diesel outlet are respectively connected to the recycled oil inlet; and / or, the oil and gas outlet of the outlet section is connected to the oil and gas inlet of the oil and gas separation system through an oil and gas pipeline, and a filtering device is provided on the oil and gas pipeline; and / or, the outlet of the catalyst to be regenerated of the moving bed reactor is connected to the inlet of the catalyst to be regenerated of the catalyst hopper system through the regeneration conveying pipeline; and / or, the catalyst regenerator is provided with an oxygen-containing gas inlet and a flue gas outlet; and / or, the regenerated catalyst outlet of the catalyst regenerator is connected to the regenerated catalyst inlet of the catalyst hopper system through a regeneration conveying pipeline.

[0022] Beneficial effects:

[0023] The present invention allows dimethylnaphthalene feedstock oil to contact an isomerization catalyst in a moving bed reactor to carry out an isomerization reaction, removes gas from the deactivated catalyst and regenerates the catalyst, and after gas removal, the regenerated catalyst is returned to the moving bed reactor for recycling, thereby achieving efficient and continuous production of 2,6-dimethylnaphthalene. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a specific embodiment of a system for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor of the present invention;

[0025] Description of Reference Numerals

[0026] 1 Moving bed reactor 2 Xylene feedstock oil inlet 3 Pipeline for production

[0027] 4 Oil and gas pipeline 5 Oil and gas separation system 6 Gas product export

[0028] 7 Distillation system 8 Gasoline outlet 9 Diesel outlet

[0029] 10 Circulating oil outlet 11 Separation and purification system 12 2,6-dimethylnaphthalene outlet

[0030] 13 Excess diesel outlet 14 Recycled oil inlet 15 Catalyst regenerator

[0031] 16 Oxygen-containing gas inlet 17 Flue gas outlet 18 Regeneration pipeline

[0032] 19 Catalyst Hopper System

[0033] I Inlet section II Reaction section III Outlet section DETAILED DESCRIPTION

[0034] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0035] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0036] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0037] In a first aspect, the present invention relates to a method for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, the method comprising:

[0038] The dimethylnaphthalene feedstock oil is brought into contact with an isomerization catalyst in a moving bed reactor and undergoes an isomerization reaction to obtain an oil-gas mixture and a catalyst to be regenerated; the oil-gas mixture is separated to obtain 2,6-dimethylnaphthalene; the catalyst to be regenerated is introduced into a catalyst hopper system to remove gas, and then introduced into a catalyst regenerator for regeneration to obtain a regenerated catalyst; the regenerated catalyst is introduced into a catalyst hopper system to remove gas, and then returned to the moving bed reactor.

[0039] It should be noted that in the method of the present invention, the dimethylnaphthalene feedstock oil contacts the isomerization catalyst in the moving bed reactor, an isomerization reaction occurs, the generated oil and gas are separated to obtain high-value 2,6-dimethylnaphthalene, and the deactivated catalyst is recycled after gas removal and regeneration. Among them, the gas removal of the catalyst to be regenerated is mainly to remove the flammable gases such as hydrogen and light hydrocarbons entrained by the catalyst, the regeneration can be char regeneration, the gas removal of the regenerated catalyst is mainly to remove the oxygen-containing gas, and then the regenerated catalyst is returned to the moving bed reactor for recycling, that is, the isomerization reaction in the method of the present invention can be efficiently and continuously reacted and regenerated based on the moving bed reactor, and the efficient and continuous production of 2,6-dimethylnaphthalene is achieved.

[0040] According to a specific embodiment of the method described in the first aspect of the present invention, the dimethylnaphthalene feedstock oil is a dimethylnaphthalene isomer mixture and / or dimethylnaphthalene-rich hydrocarbon oil;

[0041] The dimethylnaphthalene-rich oil is selected from one or more combinations of catalytic cracking light cycle oil, coal tar, medium wash oil and ethylene tar; and / or,

[0042] The content of dimethylnaphthalene in the dimethylnaphthalene-rich hydrocarbon oil is not less than 20 weight %.

[0043] It should be noted that the dimethylnaphthalene feedstock oil can also be a dimethylnaphthalene-rich fraction from other devices, and the dimethylnaphthalene content must be no less than 20% by weight. Dimethylnaphthalene-rich hydrocarbon oil components, such as catalytic cracking diesel, coal tar, ethylene tar and medium wash oil, contain a large amount of dimethylnaphthalene, among which 2,6-DMN has a high economic value; in addition to 2,6-DMN, there are 10 or more other isomers in the dimethylnaphthalene-rich hydrocarbon oil, and an isomerization reaction is required to obtain more 2,6-DMN, thereby realizing the effective utilization of the dimethylnaphthalene-rich hydrocarbon oil.

[0044] According to another specific embodiment of the method of the first aspect of the present invention, the isomerization catalyst comprises an active component and a carrier, the active component comprises a zeolite molecular sieve, and the carrier comprises a combination of one or more of alumina, silica and clay;

[0045] The zeolite molecular sieve is a medium-pore zeolite and / or a large-pore zeolite; and / or,

[0046] The zeolite molecular sieve is selected from a combination of one or more of ZSM molecular sieve, MCM molecular sieve, Beta molecular sieve and mordenite molecular sieve; and / or,

[0047] The content of the active component in the isomerization catalyst is 20 to 90 weight %; and / or,

[0048] The isomerization catalyst is a small spherical catalyst with a diameter of 0.3 to 5 mm.

[0049] It should be noted that the content of the active component in the isomerization catalyst is preferably 30 to 80% by weight, the diameter of the isomerization catalyst is preferably 1 to 4 mm, and the carrier can be a combination of a heat-resistant inorganic oxide and clay. Based on the isomerization catalyst, the isomerization reaction can be well carried out in contact with the dimethylnaphthalene feedstock oil in a moving bed reactor to efficiently produce 2,6-dimethylnaphthalene.

[0050] According to a preferred embodiment of the method described in the first aspect of the present invention, the isomerization catalyst comprises the following components based on the mass of the catalyst: 65-85% of zeolite molecular sieve, 5-30% of carrier and 5-30% of binder, wherein the zeolite molecular sieve contains 0.1-2.0wt% of phosphorus compound calculated as P2O5 and 0.1-2.0wt% of rare earth compound calculated as RE2O3. The mass proportion of zeolite molecular sieve can also be 60-85%, specifically 62%, 62.5%, 63%, 64%, 65%, 70%, 75%, etc., and the mass content of each rare earth compound calculated as RE2O3 can be 0.1-2.0wt%.

[0051] It should be noted that when using hydrocarbon oil rich in dimethylnaphthalene such as catalytic cracking light cycle oil as a raw material for dimethylnaphthalene isomerization reaction, the isomerization catalyst needs to reduce the catalytic ability of the cracking reaction and enhance the catalytic ability of the isomerization reaction according to the raw material properties of the catalytic cracking light cycle oil itself. The above-mentioned catalyst of the present invention contains a phosphorus compound and a rare earth compound, which helps to improve the acid center of the zeolite molecular sieve through rare earth modification, and phosphorus modification helps to adjust the acid distribution of the zeolite molecular sieve, thereby reducing the cracking activity of the catalyst and improving the isomerization activity of dimethylnaphthalene, and is also conducive to increasing the thermal stability and hydrothermal stability of the catalyst.

[0052] According to one embodiment of the method described in the first aspect of the present invention, the zeolite molecular sieve is mordenite or H-type mordenite. In one embodiment, the rare earth is selected from one or more of lanthanum, cerium, neodymium, and praseodymium, preferably lanthanum and cerium. In one embodiment, the carrier is clay, selected from one or more of pseudo-boehmite, kaolin, halloysite, montmorillonite, diatomaceous earth, hydrotalcite and bentonite, preferably kaolin or halloysite. In one embodiment, the binder is selected from one or more of silica sol, aluminum sol, silica aluminum sol or phosphate aluminum sol, preferably silica sol.

[0053] It should be noted that when the isomerization raw material is a hydrocarbon oil rich in dimethylnaphthalene, such as catalytic cracking light cycle oil, the hydrocarbon oil is prone to cracking reaction to produce dry gas and coking. In addition, the existing dimethylnaphthalene isomerization catalyst is mainly composed of precious metals, molecular sieves and alumina carriers, and the mass of the molecular sieve accounts for more than 60%. The alumina carrier with a small proportion is difficult to provide the catalyst strength and hydrothermal stability required for the moving bed reactor reaction. During the research process, the inventors of this application found that the carrier obtained by combining kaolin as a carrier and silica sol as a binder has a lower cracking activity, making the mordenite molecular sieve catalyst more conducive to the isomerization reaction, and less coke and dry gas are produced. It was also found that the catalyst prepared by kaolin and silica sol has better wear strength and larger bulk density, which is more conducive to the application of the catalyst in a moving bed reactor. However, in the process of using silica sol to prepare the catalyst, the silica sol easily reacts with aluminum ions to form a precipitate and becomes a gel. The gel carrier has a strong cracking performance, which leads to an increase in the dry gas and coke content in the oil and gas products when the catalyst is used for isomerization reaction. At the same time, the gel will also reduce the wear strength of the catalyst. The inventors of the present application have found that the use of acid-modified binders and adding them after dilution can overcome this problem. The modification conditions are: adding an organic acid solution to the binder sol, especially the silica sol, so that the acid solution and the silica sol are evenly stirred to form a colloid with a pH less than 7.

[0054] Therefore, the present application provides a method for preparing the catalyst of the present application, comprising:

[0055] S1. A zeolite molecular sieve is impregnated with a mixed solution of phosphate and rare earth salt, and then dried and calcined to obtain a modified zeolite molecular sieve;

[0056] S2. The modified zeolite molecular sieve is subjected to ammonium ion exchange, and then calcined in the presence of water vapor to obtain an ultrastable H-type mordenite;

[0057] S3. The ultrastable H-type mordenite and the aged carrier are formed into a catalyst precursor slurry, an acid-modified binder and a pore-forming agent are added to form a catalyst precursor sol, and the catalyst precursor sol is formed and calcined to obtain the catalyst.

[0058] Step S1 is the phosphorus and rare earth modification of zeolite molecular sieve. A mixed solution of phosphate and rare earth salt can be prepared using deionized water, and then the zeolite molecular sieve is impregnated at 70-80°C, dried at 50-120°C, and roasted at 400-500°C for 2-4h. The phosphate is selected from one or more of neutral phosphates, hydrogen phosphates, and dihydrogen phosphates; for example, phosphates, hydrogen phosphates, and dihydrogen phosphates of alkali metals such as sodium and potassium, phosphates, hydrogen phosphates, and dihydrogen phosphates of ammonium ions. The rare earth salt is one or more of rare earth nitrates, sulfates, and chlorides, such as lanthanum nitrate, cerium nitrate, and the like.

[0059] In one embodiment, in S1, based on the molecular sieve dry basis, the mixed solution contains 0.1-2.0% of phosphorus compound calculated as P2O5, 0.1-2.0% of rare earth compound calculated as RE2O3, and the weight ratio of the mixed solution of phosphate and rare earth salt to the zeolite molecular sieve is 1-5: 1. In S1, when the zeolite molecular sieve is impregnated with the mixed solution of phosphate and rare earth salt, an equal volume impregnation or an excess impregnation method is adopted.

[0060] In one embodiment, in S1, the calcination temperature is 400-500° C. and the calcination time is 2-4 hours.

[0061] Step S2 is a hydrothermal modification step of the zeolite molecular sieve. The zeolite molecular sieve modified by phosphorus and rare earth can be subjected to ammonium ion exchange, for example, mixed with an ammonium ion solution such as a 2-4 wt% ammonium chloride aqueous solution, and then subjected to ion exchange in a reactor at a temperature of 70-80°C. The zeolite molecular sieve after ammonium ion exchange is then calcined at 400-600°C for 2-4h, and water vapor is introduced during the calcination process to obtain an ultra-stable H-type mordenite.

[0062] Step S3 is a catalyst forming step. The ultrastable H-type mordenite and the aged carrier are formed into a catalyst precursor slurry, an acid-modified binder and a pore-forming agent are added to form a catalyst precursor sol, and the catalyst precursor sol is formed and calcined to obtain the catalyst. This can be done as follows:

[0063] Use deionized water to slurry the carrier, add acid to adjust the pH to 2-4, and then let it stand for aging. Ultra-stable H-type mordenite and deionized water are slurried at a solid-liquid ratio of 1:1-1:10 and added to the carrier slurry, and an acid-modified binder and pore-forming agent are added. The mixture is placed in a mixer until a uniform sol is formed, and then the spherical ball method is used for forming.

[0064] In S3, the acid-modified binder is prepared as follows: the pH of the binder is adjusted to less than 7 with an acid, wherein the acid is preferably an organic acid, and the organic acid is selected from one or more of citric acid, acetic acid, oxalic acid, and succinic acid, preferably citric acid and acetic acid;

[0065] Before the acid-modified binder is added to the catalyst precursor slurry, deionized water is also added, and the mass ratio of the deionized water to the acid-modified binder is 1-10:1.

[0066] In one embodiment, the pore former is selected from one or more of sesbania powder, methyl cellulose, carboxymethyl cellulose and cellulose acetate.

[0067] In one embodiment, in S3, the calcination temperature is 500-800°C.

[0068] According to a specific embodiment of the method according to the first aspect of the present invention, the conditions of the isomerization reaction include:

[0069] The reaction atmosphere is hydrogen and / or nitrogen, the reaction temperature is 250-450°C, the reaction pressure is 0.1-1.0 MPa, and the weight hourly space velocity of the dimethylnaphthalene feedstock oil is 0.01-5 h -1 , the volume ratio of hydrogen to oil is 100-200.

[0070] It should be noted that the method of the present invention is based on the isomerization reaction in a moving bed reactor to produce 2,6-dimethylnaphthalene. Under the above conditions, the reaction can be carried out more efficiently, so as to produce 2,6-dimethylnaphthalene more efficiently and continuously.

[0071] According to another specific embodiment of the method according to the first aspect of the present invention, the regeneration conditions include:

[0072] It is carried out in an oxygen-containing atmosphere at a temperature of 450-560°C and a pressure of 0.1-1.0 MPa.

[0073] It should be noted that when the catalyst regenerated under the above conditions is used in a moving bed reactor to carry out the method of the present invention, it can better contact with the dimethylnaphthalene feedstock oil to carry out isomerization reaction to produce 2,6-dimethylnaphthalene.

[0074] According to a specific implementation of the method according to the first aspect of the present invention, separating the oil-gas mixture comprises the following steps:

[0075] (1) performing oil-gas separation on the oil-gas mixture to obtain a gas product and a mixed oil product;

[0076] (2) fractionating and separating the mixed oil product into gasoline, diesel and circulating oil;

[0077] (3) separating and purifying the diesel to obtain 2,6-dimethylnaphthalene and remaining diesel.

[0078] It should be noted that the oil-gas mixture is first subjected to oil-gas separation to obtain gas products and liquid products, namely mixed oil products. The oil-gas separation can be carried out by fractionation, etc. to obtain products of different fractions. The gas product can include liquefied gas and dry gas, etc.; the liquid product, namely the mixed oil product, can be separated by fractionation, etc. to obtain gasoline, diesel and circulating oil; among them, the oil rich in dimethylnaphthalene, namely diesel, can be separated by conventional methods in the art to obtain 2,6-dimethylnaphthalene. The separation method can be one or more of distillation, solvent extraction, adsorption separation, crystallization separation, etc. Specifically, diesel can be separated from aromatics after desulfurization and denitrification to obtain 2,6-dimethylnaphthalene. In addition, the oil-gas mixture can also produce coke after the separation process.

[0079] According to a specific implementation of the method of the first aspect of the present invention, the method further comprises the following steps after separating the oil-gas mixture:

[0080] returning the circulating oil and the remaining diesel to the moving bed reactor to contact with the isomerization catalyst and perform an isomerization reaction; and / or,

[0081] The method further comprises the following steps before performing oil-gas separation on the oil-gas mixture:

[0082] The oil-gas mixture is subjected to filtration.

[0083] It should be noted that by returning the circulating oil and the remaining diesel to the moving bed reactor, the regenerated thermal catalyst contacts the dimethylnaphthalene feedstock oil, the circulating oil and the remaining diesel in an atmosphere of hydrogen and / or nitrogen to carry out an isomerization reaction, so that the dimethylnaphthalene feedstock oil can be more fully utilized to save energy; filtering the oil-gas mixture before oil-gas separation is beneficial to the preparation of the target product 2,6-dimethylnaphthalene with higher purity.

[0084] In a second aspect, the present invention relates to a system for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, such as Figure 1 As shown, the system includes a moving bed reactor 1, a separation system, a catalyst hopper system 19 and a catalyst regenerator 15;

[0085] The moving bed reactor 1 comprises an inlet section I, a reaction section II and an outlet section III from bottom to top; the inlet section I is provided with a dimethylnaphthalene feedstock oil inlet 2, and the upper portion of the reaction section II is provided with a catalyst inlet; the outlet section III is provided with an oil and gas outlet, which is connected to the oil and gas inlet of the separation system, and the separation system is provided with a 2,6-dimethylnaphthalene outlet 12;

[0086] An outlet for regenerated catalyst is provided at the lower portion of the reaction section II, and the outlet for regenerated catalyst is communicated with the inlet for regenerated catalyst of the catalyst hopper system 19, and the outlet for regenerated catalyst of the catalyst hopper system 19 is communicated with the inlet for regenerated catalyst of the catalyst regenerator 15; the outlet for regenerated catalyst of the catalyst regenerator 15 is communicated with the inlet for regenerated catalyst of the catalyst hopper system 19, and the outlet for regenerated catalyst of the catalyst hopper system 19 is communicated with the catalyst inlet at the upper portion of the reaction section II.

[0087] It should be noted that the system described in the second aspect of the present invention is applicable to the method described in the first aspect of the present invention. First, dimethylnaphthalene feedstock oil (dimethylnaphthalene-rich hydrocarbon oil) preheated at 180-250°C, preferably 200-250°C, enters inlet section I from dimethylnaphthalene feedstock oil inlet 2 at the bottom of the reactor and then flows upward; an isomerization catalyst such as a regenerative heat catalyst enters reaction section II from a catalyst inlet provided at the upper part of reaction section II, and the isomerization catalyst moves from top to bottom in the reactor by gravity, and in an atmosphere containing hydrogen and / or not containing hydrogen, the dimethylnaphthalene feedstock oil reversely contacts the isomerization catalyst to undergo an isomerization reaction, thereby obtaining a catalyst to be regenerated and an oil-gas mixture. Then, the oil-gas mixture enters the separation system through the outlet section III, and the target product 2,6-dimethylnaphthalene is obtained through step-by-step separation; the catalyst to be regenerated first enters the catalyst hopper system 19 to remove hydrogen, light hydrocarbons and other flammable gases, and then enters the catalyst regenerator 15 for charring regeneration, and the obtained regenerated catalyst first enters the catalyst hopper system 19 to remove oxygen-containing gas, and then returns to the moving bed reactor through the catalyst inlet at the top of the reaction section II for recycling. In summary, it can be seen that the system of the present invention realizes the safe, efficient and continuous production of 2,6-dimethylnaphthalene.

[0088] According to a specific implementation of the system described in the second aspect of the present invention, Figure 1 As shown, the separation system includes an oil-gas separation system 5, a fractionation system 7 and a separation and purification system 11;

[0089] The oil and gas outlet of the outlet section III is connected to the oil and gas inlet of the oil and gas separation system 5; the oil and gas separation system 5 is provided with a gas product outlet 6 and a mixed oil product outlet, and the mixed oil product outlet is connected to the inlet of the distillation system 7; the distillation system 7 is provided with a gasoline outlet 8, a diesel outlet 9 and a circulating oil outlet 10; the diesel outlet 9 is connected to the inlet of the separation and purification system 11, and the separation and purification system 11 is provided with a residual diesel outlet 13 and the 2,6-dimethylnaphthalene outlet 12.

[0090] It should be noted that the oil-gas separation system 5 can be a commonly used gas-liquid separation device in the art, such as a fractionation tower, etc.; the fractionation system 7 can be a fractionation tower, an absorption-stabilization system, etc.; the separation and purification system 11 can be a distillation tower, an extraction tower, a washing tower, a crystallization tower, etc. The present invention does not limit how to separate and purify the oil-gas mixture to obtain the target product 2,6-dimethylnaphthalene, and conventional methods and separation equipment in the art can be used.

[0091] According to another specific embodiment of the system according to the second aspect of the present invention, the inlet section I is provided with a recycled oil inlet 14, and the circulating oil outlet 10 and the remaining diesel outlet 13 are respectively connected to the recycled oil inlet 14; and / or,

[0092] The oil and gas outlet of the outlet section III is connected to the oil and gas inlet of the oil and gas separation system 5 through an oil and gas pipeline 4, and a filtering device is provided on the oil and gas pipeline 4; and / or,

[0093] The catalyst outlet of the moving bed reactor 1 is connected to the catalyst inlet of the catalyst hopper system 19 via the catalyst delivery pipeline 3; and / or,

[0094] The catalyst regenerator 15 is provided with an oxygen-containing gas inlet 16 and a flue gas outlet 17; and / or,

[0095] The regenerated catalyst outlet of the catalyst regenerator 15 is connected to the regenerated catalyst inlet of the catalyst hopper system 19 through a regeneration transfer pipeline 18 .

[0096] It should be noted that the catalyst to be regenerated is lifted and transported into the catalyst hopper system through the regeneration transport pipeline 3, and the hydrogen and hydrocarbons and other flammable gases attached to the catalyst are removed in the hopper, and then it is lifted and sent to the catalyst regenerator for charring and regeneration. The main air or oxygen-containing gas enters the catalyst regenerator through the oxygen-containing gas inlet 16, and burns the coke on the catalyst to be regenerated from the catalyst hopper under the oxygen atmosphere, so that the deactivated catalyst to be regenerated is regenerated, and the flue gas enters the smoke exhaust through the flue gas outlet 17 and the pipeline. In the catalyst regenerator of the present invention, the contact between the oxygen-containing main air and the catalyst is reversible, which helps to promote the complete regeneration of the catalyst.

[0097] The present invention is further described in detail by the following examples, but the present invention is not limited thereto. The materials used in the following examples can be obtained from commercial sources unless otherwise specified; the mordenite used in the examples was purchased from Yingkou Zhongbao Molecular Sieve Co., Ltd., and the MCM-22 molecular sieve was sourced from Sinopec Petrochemical Research Institute Co., Ltd.

[0098] Example 1

[0099] This example uses catalytic cracking light cycle oil as the raw material, and the specific hydrocarbon composition is shown in Table 1. Figure 1The isomerization experiment was carried out at the distillation range (system) shown. The catalyst used was MCM-22 catalyst (CAT-1), and the catalyst entered the reaction section II through the catalyst inlet at the top. Before the first experiment, the catalyst needed to be heated to 300°C in a nitrogen atmosphere for activation for 2h. After being preheated at 250°C, the catalytic cracking light cycle oil entered the bottom of the reactor through the dimethylnaphthalene feedstock oil inlet 2, and an isomerization reaction occurred with the catalyst at a reaction temperature (reactor outlet temperature) of 275°C. Hydrogen was introduced during the reaction, and the hydrogen-oil volume ratio was 150. The oil-gas mixture after the reaction was separated by the oil-gas separation system 5 to obtain gas products (liquefied gas) and mixed oil products. The mixed oil products were separated by the fractionation system 7 to obtain gasoline, diesel (containing dimethylnaphthalene) and cycle oil. The diesel was separated by the separation and purification system 11 to obtain 2,6-DMN and residual diesel (other diesel). The separated other diesel and cycle oil entered the moving bed reactor 1 through the refining oil inlet 14 for refining. After exerting its catalytic effect, the regenerated catalyst is transported by the regenerated delivery pipeline 19 to the catalyst regenerator 15 after hydrogen and light hydrocarbon gas are removed, and air combustion is used for regeneration at a regeneration temperature of 500-560° C. The regenerated catalyst can enter the catalyst hopper system through the regeneration delivery pipeline to remove oxygen-containing gas, and then return to the moving bed reactor for recycling. The reaction conditions and product distribution are shown in Table 2.

[0100] The preparation process of MCM-22 catalyst is as follows:

[0101] 1) Using 1.0 kg of MCM-22 molecular sieve as the matrix, use deionized water to prepare a 3 wt% ammonium chloride solution, and then stir the molecular sieve powder without ion exchange in a reactor at 70-80°C for 2 hours. After the solution cools down, remove the liquid and wash with deionized water. Repeat 2-3 times to obtain an ammonium exchange molecular sieve. The molecular sieve is dried at 120°C and roasted at 500°C for 3 hours. During the roasting, 30 mL / min of water vapor is introduced to obtain an ultra-stable H-type MCM-22 molecular sieve.

[0102] 2) 0.25 kg of kaolin is selected as the carrier and added to deionized water for slurrying to obtain a slurry with a certain solid content. Then, hydrochloric acid is used to adjust the pH to 2-4, and after stirring evenly, it is allowed to stand at about 70°C for a period of time to age it to obtain a mixed slurry. The H-type MCM-22 molecular sieve obtained in step 1) is added to deionized water for slurrying at a liquid-to-solid ratio of 3.0, and then added to the mixed slurry obtained in step 2), and stirred evenly in a bonding machine. 0.17 kg of aluminum stone is added to the obtained mixed slurry, and stirring continues. 10-20 g of sesbania powder is added during stirring.

[0103] 3) Stop stirring, place and age for a period of time, and use the rolling ball method to shape the obtained sol to obtain a microspherical catalyst with a diameter of 2 to 4 mm. Dry the catalyst at about 120°C for 3 hours, and calcine it in a muffle furnace at 500°C for 3 hours to obtain the catalyst. The catalyst is recorded as CAT-1.

[0104] Example 2

[0105] The catalyst in this embodiment is synthesized according to the following steps:

[0106] 1) With 1.0 kg of mordenite molecular sieve as the matrix, 1.0 kg of deionized water is used to prepare a mixed solution of 5 g of ammonium dihydrogen phosphate as P2O5, 10 g of lanthanum nitrate as La2O3 and 16 g of cerium nitrate as CeO2, the molecular sieve is impregnated at 70-80°C for 4-8 h, dried at 50-120°C, and calcined at 400-500°C for 2-4 h.

[0107] 2) Use deionized water to prepare an ammonium chloride solution with a concentration of 3% by weight, and then stir the molecular sieve powder that has not been ion-exchanged in a reactor at 70-80°C for 2 hours. After the solution cools down, remove the liquid and wash with deionized water. Repeat 2-3 times to obtain an ammonium-exchanged molecular sieve. The molecular sieve is dried at 120°C and calcined at 500°C for 3 hours. During the calcination, 30mL / min of water vapor is introduced to obtain an ultra-stable H-type mordenite molecular sieve.

[0108] 3) 0.25 kg of kaolin is selected as the carrier and added to deionized water to obtain a slurry with a certain solid content. Then, hydrochloric acid is used to adjust the pH to 2-4, and after stirring evenly, it is allowed to stand at about 70°C for a period of time to age and form a slurry. The H-type molecular sieve obtained in step 2) is added to deionized water at a liquid-to-solid ratio of 3.0 and then added to the above slurry, and stirred evenly in a bonding machine to obtain a mixed slurry.

[0109] 4) Using citric acid, adjust the pH of 0.35 kg of silica sol to 4-5, add deionized water at a mass ratio of 5:1 to dilute, and then slowly add to the mixed slurry obtained in step 3), continue to stir evenly, and add 10-20 g of sesbania powder during the stirring process.

[0110] 5) Stop stirring and place for aging for a period of time. Use the rolling ball molding method to mold the obtained sol to obtain a microspherical catalyst with a diameter of 2 to 4 mm. Dry the catalyst at about 120°C for 3 hours and calcine it in a muffle furnace at 500°C for 3 hours to obtain the catalyst. The catalyst is recorded as CAT-2.

[0111] The same feedstock oil as in Example 1 was used, and the isomerization experiment was carried out in the system of Example 1 using the catalyst CAT-2. The isomerization reaction conditions and product distribution are shown in Table 2.

[0112] Comparative Example 1

[0113] The isomerization reaction was carried out by using the same raw oil and catalyst as in Example 1, except that: Comparative Example 1 used a fixed bed reactor, the catalytic reaction and regeneration of the coking catalyst were carried out in one device (fixed bed reactor), and they were carried out alternately; in order to maintain the reaction stability and reduce the coking, diesel and circulating oil were not recycled. The operating conditions and product distribution are listed in Table 2.

[0114] Table 1

[0115] Hydrocarbon composition / wt.% Total saturated hydrocarbons 1.6 Total aromatics 98.4 Total monocyclic aromatic hydrocarbons 16.9 Total bicyclic aromatic hydrocarbons 75.3 Dimethylnaphthalene 21.2 2,6-Dimethylnaphthalene 3.4 Total tricyclic aromatic hydrocarbons 6.2 gross weight 100

[0116] Table 2

[0117]

[0118] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of the present application. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present application.

[0119] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0120] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A method for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, wherein: The method includes: The dimethylnaphthalene raw oil is brought into contact with an isomerization catalyst in a moving bed reactor to carry out an isomerization reaction, thereby obtaining an oil-gas mixture and a catalyst to be produced; Separating the oil-gas mixture to obtain 2,6-dimethylnaphthalene; The catalyst to be regenerated is allowed to enter a catalyst hopper system to remove gas, and then enter a catalyst regenerator for regeneration to obtain a regenerated catalyst; The regenerated catalyst is passed into a catalyst hopper system to be degassed and then returned to the moving bed reactor.

2. The method according to claim 1, wherein: The dimethylnaphthalene feedstock oil is a dimethylnaphthalene isomer mixture and / or dimethylnaphthalene-rich hydrocarbon oil; The dimethylnaphthalene-rich oil is selected from one or more combinations of catalytic cracking light cycle oil, coal tar, medium wash oil and ethylene tar; and / or, The content of dimethylnaphthalene in the dimethylnaphthalene-rich hydrocarbon oil is not less than 20 weight %.

3. The method according to claim 1, wherein: The isomerization catalyst comprises an active component and a carrier, wherein the active component comprises a zeolite molecular sieve, and the carrier comprises a combination of one or more of alumina, silica and clay; The zeolite molecular sieve is a medium-pore zeolite and / or a large-pore zeolite; and / or, The zeolite molecular sieve is selected from a combination of one or more of ZSM molecular sieve, MCM molecular sieve, Beta molecular sieve and mordenite molecular sieve; and / or, The content of the active component in the isomerization catalyst is 20 to 90 weight %; and / or, The isomerization catalyst is a small spherical catalyst with a diameter of 0.3 to 5 mm.

4. The method according to claim 1, wherein: The isomerization catalyst comprises the following components based on the mass of the catalyst: 65-85% of zeolite molecular sieve, 5-30% of carrier and 5-30% of binder, wherein the zeolite molecular sieve contains 0.1-2.0wt% of phosphorus compound calculated as P2O5 and 0.1-2.0wt% of rare earth compound calculated as RE2O3.

5. The method according to claim 4, wherein: The zeolite molecular sieve is mordenite or H-type mordenite; The rare earth is selected from one or more of lanthanum, cerium, neodymium and praseodymium, preferably lanthanum and cerium; The carrier is clay, selected from one or more of pseudo-boehmite, kaolin, halloysite, montmorillonite, diatomaceous earth, hydrotalcite and bentonite, preferably kaolin or halloysite; The binder is selected from one or more of silica sol, alumina sol, silica-alumina sol or phospho-alumina sol, preferably silica sol.

6. The method according to claim 1, wherein: The conditions of the isomerization reaction include: The reaction atmosphere is hydrogen and / or nitrogen, the reaction temperature is 250-450°C, the reaction pressure is 0.1-1.0 MPa, and the weight hourly space velocity of the dimethylnaphthalene feedstock oil is 0.01-5 h -1 , the volume ratio of hydrogen to oil is 100-200.

7. The method according to claim 1, wherein: The regeneration conditions include: It is carried out in an oxygen-containing atmosphere at a temperature of 450-560°C and a pressure of 0.1-1.0 MPa.

8. The method according to claim 1, wherein: Separating the oil-gas mixture comprises the following steps: (1) performing oil-gas separation on the oil-gas mixture to obtain a gas product and a mixed oil product; (2) fractionating and separating the mixed oil product into gasoline, diesel and circulating oil; (3) separating and purifying the diesel to obtain 2,6-dimethylnaphthalene and remaining diesel.

9. The method according to claim 8, wherein: The method further comprises the following steps after separating the oil-gas mixture: returning the circulating oil and the remaining diesel to the moving bed reactor to contact with the isomerization catalyst and perform an isomerization reaction; and / or, The method further comprises the following steps before performing oil-gas separation on the oil-gas mixture: The oil-gas mixture is subjected to filtration.

10. A system for producing 2,6-dimethylnaphthalene by isomerization reaction in a moving bed reactor, wherein: The system comprises a moving bed reactor (1), a separation system, a catalyst hopper system (19) and a catalyst regenerator (15); The moving bed reactor (1) comprises, from bottom to top, an inlet section (I), a reaction section (II) and an outlet section (III); the inlet section (I) is provided with a dimethylnaphthalene feedstock oil inlet (2), and the upper part of the reaction section (II) is provided with a catalyst inlet; the outlet section (III) is provided with an oil and gas outlet, which is connected to the oil and gas inlet of the separation system, and the separation system is provided with a 2,6-dimethylnaphthalene outlet (12); The lower part of the reaction section (II) is provided with an outlet for the catalyst to be regenerated, which is communicated with the inlet for the catalyst to be regenerated of the catalyst hopper system (19), and the outlet for the catalyst to be regenerated of the catalyst hopper system (19) is communicated with the inlet for the catalyst to be regenerated of the catalyst regenerator (15); the outlet for the regenerated catalyst of the catalyst regenerator (15) is communicated with the inlet for the regenerated catalyst of the catalyst hopper system (19), and the outlet for the regenerated catalyst of the catalyst hopper system (19) is communicated with the catalyst inlet at the upper part of the reaction section (II).

11. The system according to claim 10, wherein: The separation system comprises an oil-gas separation system (5), a fractionation system (7) and a separation and purification system (11); The oil and gas outlet of the outlet section (III) is connected to the oil and gas inlet of the oil and gas separation system (5); the oil and gas separation system (5) is provided with a gas product outlet (6) and a mixed oil product outlet, and the mixed oil product outlet is connected to the inlet of the fractionation system (7); the fractionation system (7) is provided with a gasoline outlet (8), a diesel outlet (9) and a circulating oil outlet (10); the diesel outlet (9) is connected to the inlet of the separation and purification system (11), and the separation and purification system (11) is provided with a residual diesel outlet (13) and the 2,6-dimethylnaphthalene outlet (12).

12. The system according to claim 11, wherein: The inlet section (I) is provided with a recycled oil inlet (14), and the circulating oil outlet (10) and the residual diesel outlet (13) are respectively connected to the recycled oil inlet (14); and / or, The oil and gas outlet of the outlet section (III) is connected to the oil and gas inlet of the oil and gas separation system (5) via an oil and gas pipeline (4), and a filtering device is provided on the oil and gas pipeline (4); and / or, The catalyst outlet of the moving bed reactor (1) is connected to the catalyst inlet of the catalyst hopper system (19) via the catalyst transport pipeline (3); and / or, The catalyst regenerator (15) is provided with an oxygen-containing gas inlet (16) and a flue gas outlet (17); and / or, The regenerated catalyst outlet of the catalyst regenerator (15) is connected to the regenerated catalyst inlet of the catalyst hopper system (19) via a regeneration transfer pipeline (18).

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