CN112299941B - Preparation method of durene - Google Patents
Preparation method of durene Download PDFInfo
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- CN112299941B CN112299941B CN202010691197.3A CN202010691197A CN112299941B CN 112299941 B CN112299941 B CN 112299941B CN 202010691197 A CN202010691197 A CN 202010691197A CN 112299941 B CN112299941 B CN 112299941B
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- C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
- C07C2/862—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms
- C07C2/864—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms the non-hydrocarbon is an alcohol
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Abstract
DureneThe preparation method comprises the steps of mixing the pseudocumene and the methanol, heating and gasifying the mixture, then feeding the mixture into an alkylation reactor, contacting the mixture with a catalyst at the temperature of between 280 and 450 ℃ and under the pressure of between 0.1 and 3.0MPa for alkylation reaction, carrying out gas-liquid separation on a product flowing out of the alkylation reactor, discharging a water phase, discharging a gas-phase hydrocarbon component in an obtained oil phase, feeding a liquid-phase hydrocarbon component into a rectification separation system, and separating C 6 Light hydrocarbon, toluene, xylene, trimethylbenzene, tetramethylbenzene and C 11 In the aromatic hydrocarbon fraction, the durene content in the durene fraction is not less than 96% by mass. The method can obtain high-purity durene products only by rectification, does not need to be crystallized, separated and purified, and has simple separation process and high production efficiency.
Description
Technical Field
The invention relates to a method for preparing durene by alkylation, in particular to a method for preparing high-purity durene by performing alkylation reaction on pseudocumene and methanol.
Background
Durene is an important fine chemical raw material, is mainly used for preparing pyromellitic dianhydride and polyimide, wherein the polyimide has excellent mechanical property, thermal stability and chemical corrosion resistance, and is widely applied to the fields of space aviation, missiles, supersonic aircrafts, atomic energy industry, electromechanical industry and the like.
Durene is produced by two methods: physical separation from C and chemical synthesis 10 Separation of durene from aromatic hydrocarbonsIs a main production method adopted at home and abroad at present; the chemical synthesis methods mainly include tetramethylbenzene isomerization, pseudocumene disproportionation isomerization, pseudocumene chloromethylation, pseudocumene methanol alkylation and the like. Wherein is derived from C 10 The separation of durene from aromatic hydrocarbon is subject to raw material supply, the chloromethylation and disproportionation isomerization of pseudocumene can not be produced in large scale due to serious pollution or immature process, the alkylation method of pseudocumene methanol has obtained certain research results in recent years, but has not been applied in large scale industry.
CN1155533A discloses a method for synthesizing durene by mixing C 9 Aromatic hydrocarbon as raw material, methanol as alkylating agent, modified hydrogen type ZSM-5 molecular sieve as catalyst, and the reaction steps of gasifying and mixing raw material, catalytic alkylation, gas-liquid separation, normal pressure distillation, cooling crystallization and centrifugal separation to obtain durene product and C 9 The conversion rate of mixed heavy aromatics is 25-35%, and the durene content in the product is 60-80%.
CN1510017A discloses a method for preparing mesitylene and durene, which comprises using pseudocumene as raw material, and co-producing mesitylene and durene under the action of catalyst, wherein the catalyst is beta zeolite, Y zeolite, ZSM-12 zeolite, MCM-22 zeolite, nu-88 zeolite, mazzite or ERS-10 zeolite, the pseudocumene conversion rate is 50-80%, and the durene proportion in the crude product is 2-10%.
CN106565406A discloses a one-step method for preparing durene, under the conditions of 320-370 ℃ and 4.0-7.0 MPa, durene is obtained by catalyzing synthesis gas, and the catalyst is a niobium, copper, zinc, aluminum and VIII family metal or an HZSM-5 molecular sieve modified by oxides thereof. The method has the CO conversion rate of over 90mol percent and the theoretical total yield of durene of 30 to 40 percent.
Disclosure of Invention
The invention aims to provide a preparation method of durene, which takes pseudocumene and methanol as raw materials to prepare durene through alkylation reaction, the separation process of reaction products is simple, the content of durene in the obtained durene fraction is high, and high-purity durene products can be obtained without further crystallization and separation.
The preparation process of durene includes mixing pseudocumene and methanol, heating to gasify, contacting with catalyst at 280-450 deg.c and 0.1-3.0 MPa for alkylation, gas-liquid separation of the effluent from the alkylation reactor, oil-water separation, and separation of C 6 Light hydrocarbon, toluene, xylene, trimethylbenzene, tetramethylbenzene and C 11 In the aromatic hydrocarbon fraction, the durene content in the durene fraction is not less than 96% by mass.
The method prepares durene by alkylating methanol and partial trimethylbenzene, the durene product has high durene content, the high-purity durene product can be obtained only by rectification and separation, crystallization, separation and purification are not needed, the separation process is simple, and the method is environment-friendly.
Drawings
FIG. 1 is a schematic diagram of the process for the alkylation of methanol with trimellitbenzene to produce durene in accordance with the present invention.
In the figure, a 1-methanol tank, a 2-pseudocumene tank, a 3-raw material premixing tank, a 4-heating furnace, a 5, 6-alkylation reactor, a 7-gas-liquid (oil-water) separating tank, an 8-methanol recovery tower, a 9-light hydrocarbon tower, a 10-toluene tower, an 11-xylene tower, a 12-xylene tower, a 13-xylene tower, a 14-methanol circulating pipeline, a 15-wastewater pipeline and a 16-trimethylbenzene circulating pipeline.
Detailed Description
The method of the invention prepares durene by alkylating methanol and unsym-trimethylbenzene, methanol in the raw materials and the unsym-trimethylbenzene are subjected to alkylation reaction to basically generate durene, and in addition, the methanol which does not undergo alkylation reaction in the reaction process can also generate light hydrocarbon and aromatization reaction. Therefore, high-purity durene can be separated by a simple rectification method, and further crystallization and separation of durene are not needed. The method has simple process and high production efficiency.
The catalyst of the method comprises 10-90 mass% of modified molecular sieve and 10-90 mass% of alumina, and preferably comprises 40-80 mass% of modified molecular sieve and 20-60 mass% of alumina. The molecular sieve is an HZSM-5 molecular sieve (hydrogen type ZSM-5) or an HEU-1 molecular sieve (hydrogen type EU-1), modifying elements in the modified molecular sieve are halogen and rare earth metal, the halogen is preferably fluorine or chlorine, the halogen content in the modified molecular sieve is 0.5-8 mass%, preferably 1-7 mass%, and the rare earth metal content in the modified molecular sieve is 0.5-5 mass%, preferably 0.8-4 mass%, more preferably 1-3.5 mass%.
The rare earth metal in the modified molecular sieve is preferably Ce and/or La. The HEU-1 molecular sieve has a silica/alumina molar ratio of 25-70, preferably 32-52; the HZSM-5 molecular sieve has a silica/alumina molar ratio of 20 to 48, preferably 25 to 48.
The preparation method of the catalyst comprises the steps of mixing the modified molecular sieve and alumina or a precursor thereof, extruding and forming, drying and roasting at 400-580 ℃.
In the preparation method of the catalyst, the alumina precursor can be one or more of aluminum sol, aluminum gel and pseudo-boehmite, and the pseudo-boehmite is preferred. In the extrusion molding, a peptizing agent is preferably added into a mixture of the modified molecular sieve and the alumina or the precursor thereof, the peptizing agent is preferably dilute nitric acid, the concentration of the peptizing agent is preferably 0.5 to 10 mass percent, more preferably 0.5 to 7 mass percent, and the dosage of the dilute nitric acid is preferably 20 to 55 percent of the mass of the mixture. The drying temperature of the extruded strip molding is preferably 90 to 120 ℃, and the drying time is preferably 2 to 6 hours.
In the invention, the preparation method of the modified molecular sieve comprises the following steps:
(1) Impregnating an HZSM-5 molecular sieve or an HEU-1 molecular sieve with an ammonium salt or an acid solution containing halogen at 50-90 ℃, drying the impregnated solid, and roasting at 450-550 ℃ to obtain a halogen modified molecular sieve, wherein the halogen is fluorine or chlorine;
(2) And (2) carrying out ion exchange on the halogen modified molecular sieve obtained in the step (1) by using a solution containing a rare earth metal compound at the temperature of 40-90 ℃, drying the solid after ion exchange, and roasting at the temperature of 450-550 ℃.
In the above method, the halogen-containing ammonium salt is selected from NH 4 F or NH 4 Cl, halogen-containing acidsHF or HCl is selected.
The rare earth metal-containing compound is preferably a nitrate or chloride of Ce and/or La.
In the above method, the concentration of the halogen-containing ammonium salt or the acid solution is preferably 3 to 25% by mass, more preferably 4 to 18% by mass. The concentration of the rare earth metal-containing compound in the solution is preferably 2 to 10% by mass, more preferably 2 to 8% by mass.
In the preparation method of the modified molecular sieve, the HZSM-5 molecular sieve or the HEU-1 molecular sieve is impregnated by ammonium salt or acid solution containing halogen at the temperature of preferably 50-90 ℃, the impregnation time is preferably 0.3-3.0 hours, and the impregnation liquid/solid mass ratio is preferably 2-8: 1, the roasting temperature of the obtained solid after impregnation is preferably 450-550 ℃, and the roasting time is preferably 3-8 hours.
When the halogen modified molecular sieve is modified by rare earth metal, the time of ion exchange by a solution containing a rare earth metal compound is preferably 0.5 to 2.5 hours, and the liquid/solid mass ratio of the ion exchange is preferably 3 to 12: 1, the roasting temperature of the solid obtained after ion exchange is preferably 450-550 ℃, and the roasting time is preferably 3-8 hours.
In the above catalyst preparation method, the calcination temperature of the dried solid after extrusion molding is preferably 400 to 550 ℃, and the calcination time is preferably 3 to 8 hours, more preferably 4 to 6 hours.
In the method, the reaction raw materials are heated and gasified and then enter an alkylation reactor, the gasification temperature is preferably 250-380 ℃, and the pressure is preferably 0.1-0.2 MPa.
After the alkylation reaction of methanol and pseudocumene, the reaction product is subjected to gas-liquid three-phase mixture separation in a gas-liquid separation tank, a gas-phase hydrocarbon component is separated from the top, a liquid-phase hydrocarbon component separated from the middle is sent to a rectification separation system, a water phase separated from the bottom enters a methanol recovery tower, the recovered methanol is reused as a reaction raw material, and water is discharged out of the reaction system. The operation temperature of the gas-liquid separation tank is preferably 30-80 ℃, and the pressure is preferably 0.1-2.0 MPa.
The temperature of the top of the methanol recovery tower is 65-75 ℃, the pressure is 0.1-0.15 MPa, and the number of theoretical plates is preferably 12-18.
The liquid phase hydrocarbon component obtained by gas-liquid separation is sent into a rectification separation system, the rectification separation system comprises a light hydrocarbon tower, a toluene tower, a xylene tower, a toluene tower and a tetramethylbenzene tower which are sequentially connected in series, and C can be sequentially separated 4 ～C 6 Light hydrocarbon, toluene, xylene, trimethylbenzene, tetramethylbenzene and C 11 The aromatic hydrocarbon fraction above.
In the rectification separation, the top effluent (fraction) of the trimethylbenzene column is mainly pseudocumene which can be reused as raw material, the top effluent of the tetramethylbenzene column is durene product, and the bottom of the tetramethylbenzene column is mainly pentamethylene which is discharged out of the reaction system.
In the rectification separation, the temperature of the top of the light hydrocarbon tower is 30-70 ℃, and the pressure is 0.1-0.15 MPa; the temperature at the top of the toluene tower is 100-130 ℃, and the pressure is 0.1-0.15 MPa; the temperature of the top of the xylene column is 132-150 ℃, and the pressure is 0.1-0.15 MPa; the top temperature of the trimethylbenzene is 95 to 175 ℃, and the pressure is 0.01 to 0.12MPa; the temperature of the top of the tetramethylbenzene tower is 120-187 ℃, and the pressure is 0.01-0.08 MPa.
The theoretical plate number of the light hydrocarbon tower is preferably 30-45, the theoretical plate number of the toluene tower is preferably 25-36, the theoretical plate number of the xylene tower is preferably 40-50, the theoretical plate number of the trimethylbenzene tower is preferably 30-40, and the theoretical plate number of the tetramethylbenzene tower is preferably 58-70.
The alkylation reactor of the invention preferably comprises a plurality of independent reactors connected in parallel, and alkylation reaction and catalyst regeneration are alternately carried out. When one reactor is used, the catalyst needs to be shut down and regenerated after carbon deposition deactivation, and when a plurality of reactors are arranged in parallel, the reactor filled with the deactivated catalyst and the reactor filled with the fresh catalyst can alternately carry out alkylation reaction and catalyst regeneration.
The alkylation reaction temperature is 290-400 ℃, preferably 290-390 ℃, the pressure is 0.2-1.5 MPa, preferably 0.3-1.2 MPa, and the mass space velocity of the reaction raw material is 0.3-2.0 hours -1 Preferably 0.5 to 1.5 hours -1 The molar ratio of the pseudocumene to the methanol is preferably 0.5 to 4:1, more preferably 0.5 to 2:1.
the invention is further described below with reference to the accompanying drawings.
In the figure 1, methanol from a methanol tank 1 and pseudocumene from a pseudocumene tank 2 enter a raw material premixing tank 3, are uniformly mixed and then enter a heating furnace 4 for heating and gasification, and then enter an alkylation reactor 5 in a gas phase to contact with a catalyst for alkylation reaction. The other alkylation reactor 6 is connected in parallel with the alkylation reactor 5 and is switched for use after the catalyst in the alkylation reactor 5 is deactivated. The product at the outlet of the alkylation reactor 5 enters a gas-liquid (oil-water) separation tank 7 after heat exchange and cooling, and gas-phase hydrocarbon (oil-water) is discharged from the upper pipeline of the gas-liquid separation tank 7<C 4 ) The components can be used as fuel for a heating furnace, the water phase (containing water and unreacted methanol) discharged from a bottom pipeline enters a methanol recovery tower 8, the methanol is discharged from the top after distillation, the methanol returns to a raw material premixing tank 3 through a methanol circulating pipeline 14, the wastewater is discharged from a bottom wastewater pipeline 15 and is sent to a wastewater treatment device, the liquid phase hydrocarbon discharged from a middle pipeline of a gas-liquid separation tank enters a rectification separation system, the liquid phase hydrocarbon firstly enters a light hydrocarbon tower 9 from the middle part and is rectified to obtain light alkane and olefin (C) 4 ～C 6 ) Discharging from the top pipeline, feeding the bottom discharge product into a toluene tower 10 from the middle part, rectifying, discharging toluene from the top pipeline, feeding the toluene as a byproduct to a product tank, feeding the bottom discharge product into a xylene tower 11 from the middle part, rectifying, discharging xylene from the top pipeline, feeding the xylene as a byproduct to the product tank, feeding the bottom discharge product into a toluene tower 12 from the middle part, rectifying, discharging trimethylbenzene from the top pipeline, returning the trimethylbenzene to a raw material premixing tank 3 from a pipeline 16 as a reaction raw material, feeding the bottom discharge product into a toluene tower 13 from the middle part, rectifying, discharging high-purity durene from the top pipeline, feeding the durene into the product tank, and discharging C from the bottom 11 The aromatic hydrocarbon fractions above, mainly containing pentamethylene and a small amount of other aromatic hydrocarbons, are sent to a storage tank for subsequent treatment.
The two parallel alkylation reactors can be switched to use, and when the catalyst in the used reactor is deactivated due to carbon deposition, the other reactor can be switched to use, and the deactivated catalyst is regenerated at the same time. The reactors are switched to be used, and the deactivated reactors can regenerate the deactivated catalysts and can also replace the fresh catalysts.
The invention is further illustrated below by way of examples, without being limited thereto.
Example 1
(1) Preparation of modified HZSM-5 molecular sieve
Taking HZSM-5 molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 42, and using NH with the concentration of 10 mass percent 4 And (3) soaking the solution F for 1.5 hours at 70 ℃ under stirring, wherein the soaking liquid/solid mass ratio is 5:1, drying the impregnated solid at 110 ℃ for 4 hours, and roasting at 500 ℃ for 6 hours to obtain the fluorine modified HZSM-5 molecular sieve, wherein the content of the F element is 2.63 mass% (X-ray fluorescence spectroscopy (XRF) analysis, the same below).
Taking a fluorine modified HZSM-5 molecular sieve, and using La (NO) with the concentration of 4 mass percent 3 ) 3 And (3) carrying out ion exchange on the solution at the temperature of 80 ℃ for 1.5 hours, wherein the liquid/solid mass ratio of the ion exchange is 10: drying the ion-exchanged solid at 110 ℃ for 4 hours, and roasting at 520 ℃ for 5 hours to obtain the fluorine and La modified HZSM-5 molecular sieve a, wherein the content of the F element is 2.63 mass percent, and the content of the La element is 1.83 mass percent.
(2) Preparation of the catalyst
Mixing the modified HZSM-5 molecular sieve a prepared in the step (1) and pseudo-boehmite powder (produced by German Condea and under the trade name Pural SB, the same below) according to the weight ratio of 60:40, adding 1 mass percent of dilute nitric acid, kneading, wherein the added dilute nitric acid accounts for 50 mass percent of the solid powder, extruding into strips, drying at 110 ℃ for 4 hours, and roasting at 540 ℃ for 5 hours to obtain the catalyst C-1, wherein the catalyst C-1 contains 60 mass percent of modified HZSM-5 molecular sieve a and 40 mass percent of alumina.
Example 2
(1) Preparation of modified HEU-1 molecular sieves
Taking HEU-1 molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 40, and using NH with the concentration of 10 mass percent 4 And (3) soaking the solution F for 1.5 hours at 70 ℃ under stirring, wherein the soaking liquid/solid mass ratio is 5:1, drying the impregnated solid at 110 ℃ for 4 hours, and roasting at 500 ℃ for 6 hours to obtain the fluorine modified HEU-1 molecular sieve, wherein the content of the F element is 2.75 mass percent.
Fluorine-modified HEU-1 molecular sieve is prepared by adding 4 wt% Ce (NO) 3 ) 3 Ion exchange the solution at 80 ℃ for 1 hourThe mass ratio of liquid to solid exchanged was 10: drying the ion-exchanged solid at 110 ℃ for 4 hours, and roasting at 520 ℃ for 5 hours to obtain the fluorine and Ce modified HEU-1 molecular sieve b, wherein the content of the F element is 2.75 mass%, and the content of the Ce element is 1.28 mass%.
(2) Preparation of the catalyst
Mixing the modified HEU-1 molecular sieve b prepared in the step (1) and pseudo-boehmite powder according to the weight ratio of 60:40, adding 1 mass percent of dilute nitric acid, kneading, wherein the added dilute nitric acid accounts for 50 mass percent of the solid powder, extruding into strips, drying at 110 ℃ for 4 hours, and roasting at 540 ℃ for 5 hours to obtain the catalyst C-2, wherein the catalyst C-2 contains 60 mass percent of modified HEU-1 molecular sieve b and 40 mass percent of alumina.
Example 3
(1) Preparation of modified HEU-1 molecular sieves
Taking HEU-1 molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 50, and using NH with the concentration of 10 mass percent 4 And soaking the solution F for 1.5 hours at 70 ℃ under stirring, wherein the soaking liquid/solid mass ratio is 5:1, drying the impregnated solid at 110 ℃ for 4 hours, and roasting at 500 ℃ for 6 hours to obtain the fluorine modified HEU-1 molecular sieve, wherein the content of the F element is 3.21 mass%.
Fluorine-modified HEU-1 molecular sieve is taken, and Ce (NO) with concentration of 4 mass percent is used 3 ) 3 And (3) carrying out ion exchange on the solution at the temperature of 80 ℃ for 1 hour, wherein the liquid/solid mass ratio of the ion exchange is 10: drying the ion-exchanged solid at 110 ℃ for 4 hours, and roasting at 520 ℃ for 5 hours to obtain the fluorine and Ce modified HEU-1 molecular sieve c, wherein the content of the F element is 3.21 mass%, and the content of the Ce element is 1.79 mass%.
(2) Preparation of the catalyst
Mixing the modified HEU-1 molecular sieve c prepared in the step (1) with pseudo-boehmite powder according to a ratio of 60:40, adding 1 mass percent of dilute nitric acid, kneading, wherein the added dilute nitric acid accounts for 50 mass percent of the solid powder, extruding into strips, drying at 110 ℃ for 4 hours, and roasting at 540 ℃ for 5 hours to obtain the catalyst C-3, wherein the catalyst C-3 contains 60 mass percent of modified HEU-1 molecular sieve C and 40 mass percent of alumina.
Example 4
(1) Preparation of modified HEU-1 molecular sieves
Taking HEU-1 molecular sieve with molar ratio of silicon oxide to aluminum oxide of 35, and adding NH with concentration of 15 mass percent 4 And soaking the solution F for 2 hours at 80 ℃ under stirring, wherein the soaking liquid/solid mass ratio is 5:1, drying the impregnated solid at 110 ℃ for 4 hours, and roasting at 500 ℃ for 6 hours to obtain the fluorine modified HEU-1 molecular sieve, wherein the content of the F element is 5.15 mass percent.
Fluorine-modified HEU-1 molecular sieve is taken, and Ce (NO) with concentration of 2 mass percent is used 3 ) 3 And (3) carrying out ion exchange on the solution at 80 ℃ for 2 hours, wherein the liquid/solid mass ratio of the ion exchange is 10: drying the ion-exchanged solid at 110 ℃ for 4 hours, and roasting at 520 ℃ for 5 hours to obtain the fluorine and Ce modified HEU-1 molecular sieve d, wherein the content of the F element is 5.15 mass%, and the content of the Ce element is 1.08 mass%.
(2) Preparation of the catalyst
Mixing the modified HEU-1 molecular sieve d prepared in the step (1) and pseudo-boehmite powder according to the weight ratio of 60:40, adding 1 mass percent of dilute nitric acid, kneading, wherein the added dilute nitric acid accounts for 50 mass percent of the solid powder, extruding into strips, drying at 110 ℃ for 4 hours, and roasting at 540 ℃ for 5 hours to obtain the catalyst C-4, wherein the catalyst C-4 contains 60 mass percent of modified HEU-1 molecular sieve d and 40 mass percent of alumina.
Example 5
Durene was prepared from pseudocumene and methanol using catalyst C-1 according to the scheme of FIG. 1. Pseudocumene and methanol as 1:1, mixing the raw materials in a raw material premixing tank 3, heating the mixture in a heating furnace to be completely vaporized, preheating the mixture to 350 ℃ at 0.1MPa, and then entering an alkylation reactor at the temperature of 380 ℃, the pressure of 1.2MPa and the feeding mass airspeed of 0.5 hour -1 Is contacted with a catalyst to react. After reaction, the materials are collected at the bottom of the reactor, leave the reactor and enter a gas-liquid separation tank 7, gas-phase hydrocarbon and liquid-phase hydrocarbon are separated at 50 ℃ and 0.1MPa, the gas-phase hydrocarbon is discharged and used as heat supply fuel for a reaction device, the liquid-phase hydrocarbon sequentially enters a light hydrocarbon tower 9, a toluene tower 10, a xylene tower 11, a trimethylbenzene tower 12 and a tetramethylbenzene tower 13, and C is sequentially separated from the tops of the towers 4 ～C 6 Light hydrocarbon, toluene, xylene, trimethyl benzene and tetramethyl benzene, and the bottom row of tetramethyl benzene towerThe discharged material is C 11 The aromatic hydrocarbon fraction and the trimethylbenzene fraction enter the raw material premixing tank for recycling, and the durene content in the durene fraction is 96.17 mass percent and can be used as durene products. The water phase discharged from the bottom of the gas-liquid separation tank 7 enters a methanol recovery tower, the methanol obtained at the top of the tower returns to the raw material premixing tank for recycling, and the wastewater at the bottom of the tower is discharged. The operating conditions and the number of plates of each rectifying column are shown in Table 1, and the reaction results are shown in Table 2.
In Table 2, the reaction evaluation results were calculated as follows
Durene yield = mesitylene conversion × durene selectivity × 100%
Example 6
Durene was prepared from pseudocumene and methanol as in example 5, except that the molar ratio of the feeds of pseudocumene and methanol was 2:1, preheating the raw materials at 285 ℃, and reacting under the following conditions: the temperature is 320 ℃, the pressure is 1.0MPa, and the feeding mass space velocity is 1.2 hours -1 . The reaction results are shown in Table 2.
Example 7
Durene was prepared from pseudocumene and methanol as in example 5, except that the feed was preheated at 300 ℃ and the reaction conditions were: the temperature is 350 ℃, the pressure is 0.8MPa, and the feeding mass airspeed is 1.0 hour -1 . The reaction results are shown in Table 2.
Example 8
Durene was prepared from pseudocumene and methanol as in example 5, except that the molar ratio of the feed of pseudocumene to methanol was 1:2, preheating the raw materials at 280 ℃, and reacting under the conditions: the temperature is 300 ℃, the pressure is 0.5MPa, and the feeding mass airspeed is 0.8 hour -1 . The reaction results are shown in Table 2.
Example 9
Durene was prepared from pseudocumene and methanol as in example 5, except that the molar ratio of the feed of pseudocumene to methanol was 1:4, preheating the raw materials at 280 ℃, and reacting under the conditions: the temperature is 290 ℃, the pressure is 0.8MPa, and the feeding mass space velocity is 1.0 hour -1 . The reaction results are shown in Table 2.
Example 10
The deactivated catalyst from the single pass reaction of example 6 was regenerated by burning with 5 vol% oxygen-containing air, and the regenerated catalyst was further subjected to the alkylation of pseudocumene and methanol under the reaction conditions described in example 6, and after 10 regenerations, the reaction results after the last regeneration are shown in Table 2, and the cumulative service time of the catalyst was 3018 hours.
Example 11
Durene was prepared from pseudocumene and methanol according to the procedure of example 5, except that the catalyst used was C-2 and the reaction results are shown in Table 3.
Example 12
Durene was prepared from mesitylene and methanol as in example 5, except that the catalyst used was C-2 and the molar ratio of the feeds of mesitylene and methanol was 2:1, preheating raw materials at 285 ℃, and reacting under the following conditions: the temperature is 320 ℃, the pressure is 1.0MPa, and the feeding mass space velocity is 1.2 hours -1 . The reaction results are shown in Table 3.
Example 13
Durene was prepared from pseudocumene and methanol as in example 5, except that the catalyst used was C-2, the feed preheat temperature was 300 ℃ and the reaction conditions were: the temperature is 350 ℃, the pressure is 0.8MPa, and the feeding mass airspeed is 1.0 hour -1 . The reaction results are shown in Table 3.
Example 14
Preparation of mesitylene and methanol according to example 5Tetramethylbenzene, except that the catalyst used was C-2, the molar ratio of the feed of pseudocumene to methanol was 1:2, the preheating temperature of the raw materials is 280 ℃, and the reaction conditions are as follows: the temperature is 300 ℃, the pressure is 0.5MPa, and the feeding mass airspeed is 0.8 hour -1 . The reaction results are shown in Table 3.
Example 15
Durene was prepared from mesitylene and methanol as in example 5, except that the catalyst used was C-2, and the molar ratio of mesitylene to methanol fed was 1:4, preheating the raw materials at 280 ℃, and reacting under the conditions: the temperature is 290 ℃, the pressure is 0.8MPa, and the feeding mass space velocity is 1.0 hour -1 . The reaction results are shown in Table 3.
Example 16
Durene was prepared from pseudocumene and methanol as in example 14, except that the catalyst used was C-3 and the reaction results are shown in Table 3.
Example 17
Durene was prepared from pseudocumene and methanol as in example 14, except that the catalyst used was C-4 and the reaction results are shown in Table 3.
Example 18
The deactivated catalyst from the single pass reaction of example 12 was regenerated by burning with 5 vol% oxygen-containing air, and the regenerated catalyst was further alkylated with mesitylene and methanol under the reaction conditions described in example 10, and after 12 regenerations, the reaction results after the last regeneration are shown in Table 3, and the cumulative service life of the catalyst was 3420 hours.
TABLE 1
TABLE 2
* For accumulating the use time
TABLE 3
* To accumulate the usage time.
Claims (13)
1. A process for preparing sym-tetramethylbenzene includes mixing meta-trimethylbenzene with methanol, heating for gasifying, introducing it to alkylating reactor, contacting it with catalyst at 280-450 deg.C and 0.1-3.0 MPa for alkylating reaction, gas-liquid separation of the product flowing out from the alkylating reactor, discharging water phase, discharging the gas-phase hydrocarbon component from oil phase, introducing the liquid-phase hydrocarbon component to rectifying-separating system, and separating C 6 Light hydrocarbon, toluene, xylene, trimethylbenzene, tetramethylbenzene and C 11 In the aromatic hydrocarbon fraction, the durene content in the durene fraction is not less than 96 mass percent, the catalyst comprises 10-90 mass percent of modified molecular sieve and 10-90 mass percent of alumina, the molecular sieve is an HEU-1 molecular sieve or an HZSM-5 molecular sieve, modified elements in the modified molecular sieve are halogen and rare earth metal, the halogen is fluorine or chlorine, the halogen content in the modified molecular sieve is 0.5-8 mass percent, and the rare earth metal content is 0.5-5 mass percent.
2. The process according to claim 1, characterized in that the molar ratio of pseudocumene to methanol is between 0.25 and 4:1.
3. the method according to claim 1, wherein the modified molecular sieve has a halogen content of 1 to 7 mass% and a rare earth metal content of 0.8 to 4 mass%.
4. The process according to claim 1, characterized in that the HEU-1 molecular sieve has a silica/alumina molar ratio of 25 to 70 and the HZSM-5 molecular sieve has a silica/alumina molar ratio of 20 to 48.
5. The process of claim 1 wherein the rare earth metal is La and/or Ce.
6. The process according to claim 1, wherein the gasification temperature is 250 to 380 ℃ and the pressure is 0.1 to 0.2MPa.
7. The process as claimed in claim 1, wherein the gas-liquid separation of the reaction product is carried out in a gas-liquid separation tank, the gas-liquid separation tank is operated at a temperature of 30 to 80 ℃ and a pressure of 0.1 to 2.0MPa, the gas-phase hydrocarbon component is separated at the top, the liquid-phase hydrocarbon component separated at the middle is fed into a rectification separation system, the aqueous phase separated at the bottom is fed into a methanol recovery tower, the recovered methanol is reused as a reaction raw material, and the reaction system is drained.
8. The process according to claim 7, wherein the temperature at the top of the methanol recovery column is 65 to 75 ℃ and the pressure is 0.1 to 0.15MPa.
9. The method as set forth in claim 7, wherein said distillation separation system comprises a light hydrocarbon column, a toluene column, a xylene column and a xylene column connected in series.
10. The process of claim 9, wherein the light ends column overhead temperature is from 30 to 70 ℃ and the pressure is from 0.1 to 0.15MPa; the temperature at the top of the toluene tower is 100-130 ℃, and the pressure is 0.1-0.15 MPa; the top temperature of the xylene tower is 132-150 ℃, and the pressure is 0.1-0.15 MPa; the temperature of the top of the trimethylbenzene tower is 95 to 175 ℃, and the pressure is 0.01 to 0.12MPa; the temperature of the top of the tetramethylbenzene tower is 120-187 ℃, and the pressure is 0.01-0.08 MPa.
11. The process according to claim 9, wherein the top effluent of the trimethylbenzene column is reused as a raw material, the top effluent of the tetramethylbenzene column is a durene product, and the bottom effluent of the tetramethylbenzene column is discharged from the reaction system.
12. The process of claim 1 wherein the alkylation reaction temperature is between 290 and 400 ℃The pressure is 0.2 to 1.5MPa, and the mass space velocity of the reaction raw material is 0.3 to 2.0 hours -1 The mol ratio of the pseudocumene to the methanol is 0.5-2: 1.
13. the process of claim 1 wherein the alkylation reactor comprises a plurality of separate reactors connected in parallel and wherein the alkylation reaction and catalyst regeneration are alternated.
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