CN110627605A - Method for preparing durene from methanol and xylene - Google Patents
Method for preparing durene from methanol and xylene Download PDFInfo
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Abstract
The invention provides a method for preparing durene from methanol and xylene, which comprises the steps of mixing the xylene with part of methanol, feeding the mixture into a reactor from a main line at the top, feeding the rest of the methanol into the reactor in a lateral line multi-section feeding mode, converting the material into a mixed hydrocarbon component rich in durene at the temperature of 250-400 ℃ and under the pressure of 0.5-2.0 MPa, separating to obtain heavy aromatic hydrocarbon rich in durene, and obtaining high-purity durene through a multi-stage freezing crystallization and centrifugal separation squeezing system. The invention adopts side methanol multi-section feeding to control the bed temperature rise during alkylation, fully utilizes the reaction heat of the upper section bed of the reactor to preserve the heat of the middle section bed and the last section bed, and reduces the reaction temperature by using a modified nano ZSM-5 molecular sieve catalyst; the xylene and mixed aromatics thereof are continuously subjected to alkylation reaction with methanol for many times, so that the selectivity of durene in an oil phase product is improved. But also fully utilizes the reaction by-products to improve the yield of durene.
Description
Technical Field
The invention relates to a preparation method of durene in the technical field of aromatic hydrocarbon production chemical industry, in particular to a method for preparing durene from methanol and xylene.
Background
Durene (1,2,4, 5-tetramethylbenzene) is commonly called durene, is an important organic chemical raw material, and is mainly used for producing pyromellitic dianhydride and further producing polyimide. With the increasing market usage of polyimide, durene is used as the main raw material for synthesizing polyimide, and the demand is increasing.
The existing synthesis method of durene comprises the alkylation of pseudocumene methanol; isomerizing and disproportionating trimethylbenzene; chloromethylating trimethyl benzene; isomerizing tetramethylbenzene; methanol to durene, and the like. The demand of durene is increasing, and thus the search for new raw materials and process routes for preparing durene is imminent.
Chinese patent document CN106565406A reports a one-step process for preparing durene from synthesis gas, which simplifies the process flow and reduces the reaction temperature.
Chinese patent document CN106076404A reports a method for preparing durene by an alkylation reaction of methanol and pseudocumene under the conditions of 350-400 ℃ and 0.6-1.5 MPa.
However, the above method has high reaction temperature and reaction pressure and high cost. The preparation of durene by using methanol with surplus productivity and xylene which is cheaper than pseudocumene and mixed aromatics thereof has important significance for reducing the preparation cost of durene.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for preparing durene from methanol and xylene, which has the advantages of low cost of raw materials, low reaction temperature and pressure and simple reaction device.
The technical scheme of the invention is as follows:
a method for preparing durene from methanol and xylene comprises the following steps:
s1, mixing dimethylbenzene (stored in a raw material storage tank) with part of methanol, feeding the mixture into a reactor filled with a multilayer modified nano ZSM-5 molecular sieve catalyst from a top main line through a preheater, feeding the rest methanol into the reactor in a lateral line multi-stage feeding mode, and controlling the reaction temperature to be 250-400 ℃, the pressure to be 0.5-2.0 MPa and the mass space velocity of the dimethylbenzene to be 0.2-2.0 h-1The mass space velocity of the methanol is 0.2-1.0 h-1To a durene-rich mixed hydrocarbon component;
s2, separating the durene-rich mixed hydrocarbon component by an oil-water separator, a liquefied gas removal tower, a product separation tower (separating components with boiling points lower than durene) and a purification tower (separating components with boiling points lower than xylene) to obtain water, dry gas, liquefied gas, durene-rich heavy aromatic hydrocarbon, C7-C9 aromatic hydrocarbon and C5-C6 light hydrocarbon;
s3, taking the dry gas as circulating gas to drive the raw materials in the reactor to flow; the C7-C9 aromatic hydrocarbon enters a raw material storage tank to be used as a reaction raw material;
s4, subjecting the durene-rich heavy aromatic hydrocarbons to multistage freezing crystallization and centrifugal separation squeezing system to obtain solid durene and heavy aromatic hydrocarbon raffinate;
s5, discharging the solid durene serving as a product out of the system, and feeding the heavy aromatic residual liquid into a mixed aromatic storage tank to serve as a reaction raw material.
The water is discharged out of the system through an oil-water separator; discharging the liquefied gas from the system through a liquefied gas removal tower; and C5-C6 light hydrocarbon is discharged out of the system through the purification tower.
Step S1 further includes mixing the dry gas with xylene and a portion of methanol, and passing the mixture through a preheater to enter the reactor from the top main line.
The modified nano ZSM-5 molecular sieve catalyst comprises a ZSM-5 molecular sieve carrier and active metal, wherein the grain size of the ZSM-5 molecular sieve carrier is 210 nm-300 nm, the active metal is one or more of zinc, iron, magnesium, calcium and rare earth elements, and the mass fraction of the active metal is 0.1-2.0%.
The xylene in the invention is from pure xylene or mixed aromatic hydrocarbon containing xylene, i.e. the pure xylene or mixed aromatic hydrocarbon containing xylene is used as reaction raw material.
Preferably, the reaction temperature in step S1 is 250-340 ℃.
The preparation method of the modified nano ZSM-5 molecular sieve catalyst comprises the following steps:
s1, uniformly mixing a silicon source, an aluminum source, an alkali source, n-butylamine, deionized water and ZSM-5 seed crystals to form a mixed solution, crystallizing the mixed solution at 40-190 ℃ for 12-120 h, and washing, drying and roasting a solid product obtained by crystallization to obtain a ZSM-5 molecular sieve carrier;
s2, carrying out alkali treatment, ammonium exchange, extrusion molding, acid treatment and metal salt solution impregnation on the ZSM-5 molecular sieve carrier in the step S1, and roasting to obtain the modified nano ZSM-5 molecular sieve catalyst;
OH in the step S1 Mixed liquid System (crystallization reaction System)-:SiO2:A12O3The molar ratio of n-butylamine to water is 2-4:7-15:0.1-1:0.5-5: 300-1100.
Preferably OH in the mixed liquid system (crystallization reaction system) of step S1-:SiO2:A12O3The molar ratio of n-butylamine to water is 2.3-3.5:10-13.5:1:2.5-5.5: 250-.
The silicon source is one or a mixture of tetraethyl orthosilicate, silica sol and water glass; the aluminum source is one or more of aluminum sulfate, aluminum isopropoxide and sodium metaaluminate; the alkali source is at least one of sodium hydroxide and potassium hydroxide.
Preferably, the seed crystal is added in the step S1 in an amount of 1-8% of the yield of the durene-producing catalyst.
Preferably, the crystallization temperature in the step S1 is 140-190 ℃, and the crystallization time is 12-120 h.
In the step S2, the alkali treatment is to soak the ZSM-5 molecular sieve carrier in an alkali solution at 60-90 ℃ for 15-200min, wherein the alkali solution is one or two of a sodium hydroxide solution and a potassium hydroxide solution, and the concentration of the alkali solution is 0.05-0.3 mol/L.
In the step S2, the ammonium exchange is to perform ion exchange on the ZSM-5 molecular sieve carrier subjected to alkali treatment for 30-200min at 60-90 ℃ by using ammonium nitrate, and the concentration of the ammonium nitrate solution is 0.05-0.3 mol/L.
In the step S2, the acid treatment is to soak the ion exchanged ZSM-5 molecular sieve carrier for 1-5h at 60-80 ℃, wherein the acid solution is one or more of sulfuric acid, hydrochloric acid, hydrofluoric acid and acetic acid, and the concentration of the acid solution is 0.1-2.0 mol/L.
In the step S2, the metal salt solution is one or more of copper nitrate, magnesium nitrate and zinc nitrate, and the mass fraction of the impregnated metal salt is 0.01-0.05%.
The method comprises the steps of mixing dimethylbenzene and part of methanol, feeding the mixture into a reactor from a main line at the top through a preheater, feeding the rest of methanol into the reactor (alkylation reactor) in a lateral line multistage feeding mode, reacting the materials at the temperature of 250-400 ℃ and under the pressure of 0.5-2.0 MPa to convert the materials into mixed hydrocarbon components rich in durene, and separating the mixed hydrocarbon components to obtain water, dry gas, liquefied gas, heavy aromatic hydrocarbons rich in durene, C7-C9 aromatic hydrocarbons and C5-C6 light hydrocarbons. The heavy aromatic hydrocarbon rich in durene is subjected to multistage freezing crystallization and centrifugal separation squeezing system to obtain solid durene and heavy aromatic hydrocarbon residual liquid with the purity of 97%, and the C7-C9 aromatic hydrocarbon and heavy aromatic hydrocarbon residual liquid are returned to the raw material storage tank. Wherein the durene content in the oil phase of the reacted mixed hydrocarbon component reaches 19 percent.
Compared with the prior durene synthesis technology, the method has the following advantages: 1) the reaction temperature is reduced, at present, the reaction temperature of trimethylbenzene and methanol is 350-400 ℃, under the condition of the same molar weight, xylene consumes one more methanol than trimethylbenzene, so that the reaction temperature is further increased to be unfavorable for reaction (the catalyst is easy to deposit carbon), and byproducts are increased, the temperature rise of a bed layer during alkylation can be controlled by a way of adding side-line methanol multi-stage feeding in the reactor, so that the reaction can be carried out at lower temperature and pressure, the reaction heat of an upper-stage bed layer of the reactor can be fully utilized to keep the temperature of a middle-stage bed layer and a last-stage bed layer, and the reaction temperature is further reduced, the reaction temperature is further reduced by using the modified nano ZSM-5 molecular sieve catalyst, and the reaction temperature can be stably controlled at 250-360 ℃ due to high specific surface, high activity and high stability, so that the byproducts are effectively reduced; xylene and mixed aromatics (C7-C9 aromatic hydrocarbon and heavy aromatic hydrocarbon raffinate) thereof and methanol are continuously subjected to alkylation reaction for many times, so that the selectivity of durene in an oil phase product is improved to 45%; C7-C9 aromatic hydrocarbon and heavy aromatic hydrocarbon residual liquid are returned to the raw material storage tank, and the yield of durene is improved by fully utilizing reaction byproducts and can reach 35 percent.
Drawings
FIG. 1 is a flow chart of the process for preparing durene from methanol and xylene according to the present invention;
wherein 1 is a reactor, 2 is an oil-water separator, 3 is a liquefied gas removal tower, 4 is a product separation tower, 5 is a purification tower, 6 is a freezing crystallization and centrifugal separation squeezing system, and 7 is a heavy aromatic hydrocarbon storage tank.
The invention is further illustrated by the following examples.
Detailed Description
Example 1 preparation of modified Nano ZSM-5 molecular Sieve catalyst
Uniformly mixing 0.28g of sodium metaaluminate, 0.44g of sodium hydroxide and 21g of deionized water serving as reaction raw materials, adding 10g of silica sol, uniformly mixing, adding 1.2g of n-butylamine, uniformly mixing, adding 0.08g of ZSM-5 seed crystal, uniformly mixing to form a mixed solution, adding the mixed solution into a stirring kettle, adjusting the stirring speed to 300r/min, heating to 170 ℃, crystallizing for 72 hours to obtain a ZSM-5 molecular sieve carrier, wherein the grain size of the ZSM-5 molecular sieve carrier is about 220nm, taking 5g of the obtained ZSM-5 molecular sieve carrier, soaking the ZSM-5 molecular sieve carrier by using a sodium hydroxide solution with the mass fraction of 0.5% at the temperature of 80 ℃ for 2 hours, exchanging for 2 hours by using an ammonium nitrate solution with the concentration of 0.4M, and extruding and forming. Treating extruded ZSM-5 with 0.2M hydrofluoric acid solution at 40 ℃ for 4h, soaking the extruded ZSM-5 with 0.05 percent zinc nitrate for 24h, and roasting the ZSM-5 at 550 ℃ for 6h to obtain the modified nano ZSM-5 molecular sieve catalyst.
Example 2 preparation of modified Nano ZSM-5 molecular Sieve catalyst
Uniformly mixing 0.31g of sodium metaaluminate, 0.51g of sodium hydroxide and 27g of deionized water serving as reaction raw materials, adding 10g of silica sol, uniformly mixing, adding 1.48g of n-butylamine, uniformly mixing, adding 0.06g of ZSM-5 seed crystal, uniformly mixing to form a mixed solution, placing the mixed solution into a stirring kettle, adjusting the stirring speed to 300r/min, heating to 160 ℃, crystallizing for 72 hours to obtain a ZSM-5 molecular sieve carrier, wherein the grain size of the ZSM-5 molecular sieve carrier is about 300nm, taking 5g of the obtained ZSM-5 molecular sieve, treating for 2 hours at 80 ℃ by using a sodium hydroxide solution with the mass fraction of 0.4%, exchanging for 2 hours by using an ammonium nitrate solution with the concentration of 0.5M, and extruding and forming. Treating the extruded ZSM-5 with a sulfuric acid solution with the concentration of 0.2M at 50 ℃ for 4h, soaking the ZSM-5 with copper nitrate with the mass fraction of 0.04% for 24h, and roasting the ZSM-5 at 550 ℃ for 6h to obtain the modified nano ZSM-5 molecular sieve catalyst.
Example 3
Uniformly mixing 0.34g of aluminum isopropoxide, 0.41g of sodium hydroxide and 25g of deionized water serving as reaction raw materials, adding 10g of silica sol, uniformly mixing, adding 0.87g of n-butylamine, uniformly mixing, adding 0.09g of ZSM-5 seed crystal, uniformly mixing to form a mixed solution, adding the mixed solution into a stirring kettle, adjusting the stirring speed to 300r/min, heating to 170 ℃, crystallizing for 72 hours to obtain a ZSM-5 molecular sieve, wherein the grain size of a ZSM-5 molecular sieve carrier is about 210nm, taking 5g of the obtained ZSM-5 molecular sieve, treating for 2 hours at 80 ℃ by using a potassium hydroxide solution with the mass fraction of 0.5%, exchanging for 1 hour by using an ammonium nitrate solution with the concentration of 0.6M, and extruding and forming. Treating extruded ZSM-5 with a 0.2M nitric acid solution at 30 ℃ for 4h, soaking the extruded ZSM-5 with magnesium nitrate with the mass fraction of 0.05% for 24h, and roasting the impregnated ZSM-5 at 550 ℃ for 6h to obtain the modified nano ZSM-5 molecular sieve catalyst.
Example 4
As shown in FIG. 1, a reactor 1 was filled with 1200kg of the modified nano ZSM-5 molecular sieve catalyst of example 1 in five layers, and main methanol, xylene and dry gas were preheated to 320 ℃ and fed from the top of the reactor 1, with a methanol flow of 65kg/h and a xylene flow of 615 kg/h. The flow rates of methanol fed to the second, third and fourth layer side lines were 65kg/h, respectively. Keeping the temperature of each bed layer at 330-340 ℃, and the dry gas flow at 543 kg/h. The reaction product (the mixed hydrocarbon component rich in durene) is separated into dry gas, waste water, liquefied gas and mixed hydrocarbon (heavy aromatic hydrocarbon rich in durene, C7-C9 aromatic hydrocarbon and C5-C6 light hydrocarbon) by an oil-water separator 2, and the flow of the waste water is 145kg/h and is discharged out of the system; mixed hydrocarbons enter a liquefied gas removal tower 3, the pressure at the top of the liquefied gas removal tower 3 is controlled to be 0.5MPa, the temperature is controlled to be 121 ℃, liquefied gas and dry gas are produced, the liquefied gas flows through a condensing system, the liquefied gas flows are 55kg/h and is discharged out of the system, the dry gas is used as circulating gas, the mixed hydrocarbons (heavy aromatic hydrocarbons rich in durene, C7-C9 aromatic hydrocarbons and C5-C6 light hydrocarbons) at the bottom of the liquefied gas removal tower 3 enter a product separation tower 4, the temperature at the bottom of the product separation tower is controlled to be 208 ℃, the heavy aromatic hydrocarbons rich in durene are produced, the flow is 210kg/h, after multistage freezing crystallization and centrifugal separation and squeezing system 7, solid durene (the yield is 171kg/h) with the purity of 97% and heavy aromatic hydrocarbon raffinate are obtained, and the heavy aromatic hydrocarbon raffinate enters a heavy aromatic hydrocarbon storage tank 7; mixed hydrocarbons (C7-C9 aromatic hydrocarbons and C5-C6 light hydrocarbons) at the top of the product separation tower 4 enter a purification tower 5, the temperature at the bottom of the purification tower 5 is controlled at 184 ℃, the flow of the produced aromatic hydrocarbons (C7-C9 aromatic hydrocarbons) is 393kg/h, the produced aromatic hydrocarbons (C7-C9 aromatic hydrocarbons) are returned to a raw material storage tank, and the flow of the produced light hydrocarbons (C5-C6 light hydrocarbons) at the top of the purification tower 5 is 55kg/h, and the produced hydrocarbons are. The yield of durene was 35.1%.
Example 5
As shown in figure 1, a reactor 1 is filled with 1200kg of the modified nano ZSM-5 molecular sieve catalyst of the example 2 in five layers, main line methanol, xylene and circulating dry gas are preheated to 320 ℃ and fed from the top of the reactor 1, the flow rate of the methanol is 80kg/h, and the flow rate of the xylene is 820 kg/h. The flow rates of methanol fed to the second, third and fourth layer side lines were 80kg/h, respectively. Keeping the temperature of each bed layer at 340-350 ℃, and the dry gas flow at 610 kg/h. The reaction product is separated by an oil-water separator 2 to obtain dry gas, waste water and mixed hydrocarbon (rich in durene heavy aromatics, C7-C9 aromatics and C5-C6 light hydrocarbons), and the flow of the waste water is 178kg/h and is discharged out of the system; the mixed hydrocarbons enter a liquefied gas removal tower 3, the pressure at the top of the liquefied gas removal tower 3 is controlled to be 0.5MPa, the temperature is controlled to be 121 ℃, liquefied gas and dry gas are produced, the liquefied gas and the dry gas pass through a condensation system, the flow rate of the liquefied gas is 68kg/h, and the dry gas is taken as circulating gas. Mixed hydrocarbons (rich in durene heavy aromatics, C7-C9 aromatics and C5-C6 light hydrocarbons) at the bottom of the liquefied gas removal tower 3 enter a product separation tower 4, the temperature of the bottom of the product separation tower 4 is controlled to be 208 ℃, the heavy aromatics rich in durene are produced, the flow rate is 260kg/h, after multistage freezing crystallization and centrifugal separation squeezing system 7, solid durene (the yield is 210kg/h) with the purity of 97% and heavy aromatic raffinate are obtained, the heavy aromatic raffinate enters a heavy aromatic storage tank 7 and then returns to a raw material storage tank; mixed hydrocarbons (C7-C9 aromatic hydrocarbons and C5-C6 light hydrocarbons) at the top of the product separation tower 4 enter a purification tower 5, the temperature of the bottom of the purification tower 5 is controlled to be 184 ℃, the flow rate of the produced aromatic hydrocarbons (C7-C9 aromatic hydrocarbons) is 485kg/h, the produced aromatic hydrocarbons (C7-C9 aromatic hydrocarbons) return to a raw material storage tank, and the flow rate of the produced light hydrocarbons (C5-C6 light hydrocarbons) at the top of the tower is 75kg/h, and the. The yield of durene was 32.3%.
Example 6
As shown in FIG. 1, a reactor 1 was filled with 1200kg of the modified nano ZSM-5 molecular sieve catalyst of example 3 in five layers, and main line methanol, mixed aromatics containing xylene and dry gas were preheated to 320 ℃ and fed from the top of the reactor 1, with a flow rate of methanol of 65kg/h and a flow rate of mixed aromatics containing xylene of 615 kg/h. The flow rates of methanol fed to the second, third and fourth layer side lines were 65kg/h, respectively. Keeping the temperature of each bed layer at 300-320 ℃, and the flow of dry gas at 580 kg/h. The reaction product is separated by an oil-water separator 2 to obtain dry gas, waste water and mixed hydrocarbon (rich in durene heavy aromatics, C7-C9 aromatics and C5-C6 light hydrocarbons), and the flow of the waste water is 145kg/h and is discharged out of the system; mixed hydrocarbons enter a liquefied gas removal tower 3, the pressure at the top of the liquefied gas removal tower 3 is controlled to be 0.5MPa, the temperature is controlled to be 121 ℃, liquefied gas and dry gas are produced, the liquefied gas flows through a condensing system, the liquefied gas flows are 50kg/h and is discharged out of the system, the dry gas is used as circulating gas, the mixed hydrocarbons (heavy aromatic hydrocarbons rich in durene, C7-C9 aromatic hydrocarbons and C5-C6 light hydrocarbons) at the bottom of the liquefied gas removal tower 3 enter a product separation tower 4, the temperature at the bottom of the product separation tower 4 is controlled to be 208 ℃, heavy aromatic hydrocarbons rich in durene are produced, the flow is 197kg/h, after multistage freezing crystallization and centrifugal separation and squeezing system 6, solid durene (the yield is 171kg/h) with the purity of 97% and heavy aromatic hydrocarbon raffinate are obtained, and the heavy aromatic hydrocarbon raffinate enters a heavy aromatic hydrocarbon storage tank 7; mixed hydrocarbons (C7-C9 aromatic hydrocarbons and C5-C6 light hydrocarbons) at the top of the product separation tower 4 enter a purification tower 5, the temperature at the bottom of the purification tower 5 is controlled to be 184 ℃, the flow rate of the produced aromatic hydrocarbons (C7-C9 aromatic hydrocarbons) is 385kg/h, the produced aromatic hydrocarbons (C7-C9 aromatic hydrocarbons) at the top of the purification tower are returned to a raw material storage tank, and the flow rate of the produced light hydrocarbons (C5-C6 light hydrocarbons) at the top of the purification. The yield of durene was 35.1%.
Claims (5)
1. A method for preparing durene from methanol and xylene is characterized in that: the method comprises the following steps:
s1, mixing dimethylbenzene and part of methanol in a raw material storage tank, feeding the mixture into a reactor (1) filled with a multilayer modified nano ZSM-5 molecular sieve catalyst from a top main line through a preheater, feeding the rest of methanol into the reactor (1) in a lateral line multi-stage feeding mode, and controlling the reaction temperature to be 250-400 ℃, the pressure to be 0.5-2.0 MPa and the mass space velocity of the dimethylbenzene to be 0.2-2.0 h-1The mass space velocity of the methanol is 0.2-1.0 h-1To a durene-rich mixed hydrocarbon component;
s2, separating the durene-rich mixed hydrocarbon component by an oil-water separator (2), a liquefied gas removal tower (3), a product separation tower (4) and a purification tower (5) to obtain water, dry gas, liquefied gas, durene-rich heavy aromatic hydrocarbon, C7-C9 aromatic hydrocarbon and C5-C6 light hydrocarbon;
s3, taking the dry gas as circulating gas to drive the raw materials in the reactor to flow; the C7-C9 aromatic hydrocarbon enters a raw material storage tank to be used as a reaction raw material;
s4, subjecting the durene-rich heavy aromatic hydrocarbons to multistage freezing crystallization and centrifugal separation squeezing system (6) to obtain solid durene and heavy aromatic hydrocarbon raffinate;
s5, discharging the solid durene serving as a product out of the system, and feeding the heavy aromatic residual liquid into a mixed aromatic storage tank (7) to serve as a reaction raw material;
the modified nano ZSM-5 molecular sieve catalyst comprises a ZSM-5 molecular sieve carrier and active metal, wherein the grain size of the ZSM-5 molecular sieve carrier is 210 nm-300 nm, the active metal is one or more of zinc, iron, magnesium, calcium and rare earth elements, and the mass fraction of the active metal is 0.1-2.0%.
2. The method of claim 1, wherein the method comprises the following steps: step S1 further includes mixing the dry gas with xylene and a portion of methanol, and passing the mixture through a preheater to enter the reactor from the top main line.
3. The method of claim 1, wherein the method comprises the following steps: in the step S1, the reaction temperature is 250-340 ℃.
4. The method of claim 1, wherein the method comprises the following steps: the preparation method of the modified nano ZSM-5 molecular sieve catalyst comprises the following steps:
s1, uniformly mixing a silicon source, an aluminum source, an alkali source, n-butylamine, deionized water and ZSM-5 seed crystals to form a mixed solution, crystallizing the mixed solution at 40-190 ℃ for 12-120 h, and washing, drying and roasting a solid product obtained by crystallization to obtain a ZSM-5 molecular sieve carrier;
s2, carrying out alkali treatment, ammonium exchange, extrusion molding, acid treatment and metal salt solution impregnation on the ZSM-5 molecular sieve carrier in the step S1, and roasting to obtain the modified nano ZSM-5 molecular sieve catalyst;
OH in the step S1 Mixed liquid System-:SiO2:A12O3The molar ratio of n-butylamine to water is 2-4:7-15:0.1-1:0.5-5: 300-1100.
5. The method of claim 4, wherein the methanol and the xylene are used for preparing durene, and the method comprises the following steps: step S1 mixed liquid system OH in preparation method of modified nano ZSM-5 molecular sieve catalyst-:SiO2:A12O3The molar ratio of n-butylamine to water is 2.3-3.5:10-13.5:1:2.5-5.5: 250-.
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