CN106866328A - A kind of method of methyl alcohol high selectivity aromatic hydrocarbons - Google Patents

Abstract

The invention discloses a method for producing aromatics with high selectivity from methanol, which relates to aromatics. Catalyst pretreatment; catalytic reaction: After the catalyst is pretreated, the reaction raw materials are passed through to form methanol and hydrogen capture-removal agent. Under the condition of space velocity of 500-10000h- ¹ , the product aromatics is obtained through solid catalyst bed layer reaction . Add the salt compounds of metal elements into the solvent for ultrasonic dispersion, then add modified acidic zeolite molecular sieves, and continue ultrasonic dispersion to obtain a mixture; after the mixture is suction filtered and washed, the obtained filter cake is dried; the dried sample is roasted, After reduction, the catalyst is obtained. The method for producing aromatics from methanol has the characteristics of excellent aromatics selectivity, low methane and C ₅₊ hydrocarbon selectivity, and high catalyst stability, wherein the aromatics selectivity can reach more than 85%, and the methane selectivity is lower than 2%.

Description

A method for producing aromatics with high selectivity from methanol

technical field

The invention relates to aromatics, in particular to a method for producing aromatics with methanol with high selectivity.

Background technique

Aromatics are important chemical basic raw materials, and benzene, toluene and xylene (ie BTX) in light aromatics are the most important basic chemicals for petrochemical products. At present, the production of aromatics mainly comes from petroleum routes, including catalytic reforming, naphtha hydrogenation, pyrolysis gasoline hydrogenation and aromatics conversion, etc. Due to the increasingly serious problems of resource depletion and environmental pollution caused by the extensive use of petroleum, it is particularly urgent to develop methods for producing aromatics through non-petroleum routes. On the other hand, the technology of producing methanol from coal is quite mature, and methanol can be converted into important chemical raw materials including olefins and aromatics through acid-catalyzed conversion. Therefore, the development of methanol-to-aromatics technology can provide a good way for efficient and clean utilization of coal resources, and can replace or partially replace the route of petroleum resources. It is a sustainable development strategy in line with my country's national conditions.

The difficulty in the study of direct synthesis of aromatics from methanol mainly lies in the development of catalysts with high selectivity and high stability. Wei Fei et al. found that the selectivity of aromatics on the Ag-supported H-ZSM-5 catalyst was 55%, and xylene was the main component, and the yield of aromatics on the H-ZSM-5 catalyst modified by Zn and P increased to 75%. % (Acta Phys.-Chim. Sin., 2013, 29, 1281). Freeman et al. investigated the methanol-to-aromatics performance of 13 groups of oxides and H-ZSM-5 molecular sieve physical mixture, and the addition of gallium oxide can significantly increase the yield of C ₈ and C ₉ aromatics (Catal.Lett., 2002, 82, 217) . Ono et al. also found that Ga/H-ZSM-5 and Zn/H-ZSM-5 are better methanol aromatization catalysts, with yields of 48% and 67% respectively (Faraday Transactions, 1988, 84, 1091). Barthos et al. investigated the MTA reaction of H-ZSM-5 catalyst supported by metal carbide Mo ₂ C. The results showed that molybdenum carbide can also improve the yield of aromatic hydrocarbons. When the loading amount of molybdenum carbide is 5%, the yield of aromatic hydrocarbons can be It reaches 63%, which is twice the yield of no load (J. Catal., 2007, 247, 368). In addition, La, as a promoter of Zn/H-ZSM-5 catalyst, can also increase the yield of aromatics, which is 64% (J. Chem. Eng., 2011, 19, 439). Chinese patent CN200610012703.1 reports the process of converting methanol into aromatics, using modified ZSM-5 molecular sieve as a catalyst, for example, the selectivity of aromatics after Ga and La modification is 70%-75%. Chinese patent CN 201010261730.9 reports that a mixture of Zn and Ni or P and H-ZSM-5 is used as a catalyst, and the selectivity of aromatics is about 70%.

In the above results, although relatively high aromatics selectivity can be obtained on some catalysts, the content of C ₉₊ aromatics is relatively large, while the selectivity of light aromatics BTX is not high, and most of the above studies are carried out in short reaction times The experimental data obtained within (generally less than 10h). In most reactions, as the reaction proceeds, carbon deposits occur on the catalyst, which covers the acid active centers on the catalyst, resulting in a decrease in catalyst activity, and even metal sintering of catalyst promoters, resulting in poor catalyst stability and shortened life. Therefore, the development of methods and catalysts for methanol-to-aromatics with high aromatics yield and high stability is the key to the industrialization of this reaction.

Contents of the invention

The invention aims to provide a method for preparing aromatics from methanol with high selectivity.

The method for producing aromatics with high selectivity of methanol comprises the following steps:

1) catalyst pretreatment, the catalyst is metal oxide/acidic zeolite molecular sieve compound;

In step 1), the preparation method of the metal oxide/acidic zeolite molecular sieve compound can be:

(1) adding the salt compound of the metal element into the solvent for ultrasonic dispersion, then adding the modified acidic zeolite molecular sieve, and continuing the ultrasonic dispersion to obtain the mixture;

In step (1), the mass ratio of the salt compound of the metal element to the solvent can be 1: (0-100); the salt compound can be selected from nitrate, hydrochloride, acetylacetonate, vinegar At least one of salts, bromides, etc.; the time for the ultrasonic dispersion can be 0.5-10 h; the time for continuing the ultrasonic dispersion can be 0.5-10 h.

(2) After the mixture obtained in step (1) is suction filtered and washed, the gained filter cake is dried;

In step (2), vacuum drying may be used for the drying, the drying temperature may be 40-100° C., and the drying time may be 1-48 hours.

(3) Calcining and reducing the dried sample in step (2) to obtain the catalyst.

In step (3), the roasting method can be: move the dried sample to a tube furnace and roast it with NO/Ar mixed gas containing NO, the heating rate is 0.5-2°C/min, and the temperature is 300-650°C, the roasting time is 1-24h; the volume percentage of NO in the NO/Ar mixed gas can be 5%-20%; the reduction can be carried out in an atmosphere containing H ₂ , the volume percentage of H ₂ It can be 5%-50%, the heating rate is 0.5-5°C/min, the temperature is 250-500°C, and the reduction time is 0.5-10h.

The specific method of catalyst pretreatment may be: heating the catalyst from room temperature to 300-650°C at a heating rate not higher than 20°C/min in an inert gas of nitrogen, argon or helium, and keeping it for 10-300min .

2) Catalytic reaction: After the catalyst is pretreated, the reaction raw materials are passed through to form methanol and hydrogen capture-removal agent, and the product aromatics are obtained through solid catalyst bed reaction at a space velocity of 500-10000h ^-1 .

In step 2), the molar ratio of methanol and hydrogen capture-removal agent in the methanol and hydrogen capture-removal agent can be (0.05～100):1; the hydrogen capture-removal agent can be selected from carbon monoxide , carbon dioxide, sulfur dioxide, unsaturated olefins, unsaturated alkynes, nitrogen oxides, aldehyde compounds, ketone compounds, etc.; the unsaturated olefins can be selected from ethylene, propylene, butene, pentene, At least one of hexene, etc.; the unsaturated alkyne is one or more of acetylene, propyne, butyne, and the nitrogen oxide is nitrogen monoxide, nitrogen dioxide, nitrous oxide, etc. At least one of, the aldehyde compound is at least one of acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, benzaldehyde, etc., and the ketone compound can be selected from acetone, butanone, pentanone, cyclohexane At least one of ketones, etc.; the unsaturated alkene can be selected from at least one of ethylene, propylene, butene, pentene, hexene, etc.; the unsaturated alkyne can be selected from acetylene, propyne, butylene At least one of alkynes, etc., the nitrogen oxides can be selected from at least one of nitric oxide, nitrogen dioxide, nitrous oxide, etc., and the aldehyde compounds can be selected from acetaldehyde, propionaldehyde, butyrate At least one of aldehyde, valeraldehyde, benzaldehyde, etc., and the ketone compound can be selected from at least one of acetone, methyl ethyl ketone, pentanone, cyclohexanone, etc. The composition of the solid catalyst is a mixture of metal and modified acidic zeolite molecular sieve, or a mixture of metal oxide and modified acidic zeolite molecular sieve, wherein the mass percentage of metal or metal oxide can be 0.5% to 40%, and the rest is modified Acidic zeolite molecular sieve; the metal can be selected from at least one of Cu, Fe, Ni, Co, Ru, Au, Pt, Pd, Ir, Zn, Zr, Ga, Cr, M, Ti, W, etc., so The metal oxide can be selected from at least one of metal oxides such as Cu, Fe, Ni, Co, Ru, Au, Pt, Pd, Ir, Zn, Zr, Ga, Cr, M, Ti, W, etc.; The modified acidic zeolite molecular sieve can be selected from zeolite molecular sieves modified by at least one element of Zn, Zr, Mn, Mo, Cu, Cr, Ga, etc., including ion exchange, etc., wherein the mass of the modified element is 100% The content can be 0.1%～10.0%, and the rest is acidic zeolite molecular sieve; the acidic zeolite molecular sieve can be selected from H-MCM-22, H-Beta, H-Y, H-X, H-ZSM-5, H-MOR, H- At least one of SSZ-13 and the like; the temperature of the reaction may be 300-600° C., and the pressure of the reaction may be 0.1-5.0 MPa.

Compared with prior art, technical effect of the present invention is as follows:

(1) The present invention shows excellent catalytic performance for methanol-to-aromatics, that is, the addition of a hydrogen capture-removal agent significantly promotes the selectivity of aromatics, and the product distribution is characterized by low methane, low heavy alkanes, and high aromatics selectivity. The selectivity can reach more than 90%.

(2) The reaction raw material hydrogen capture-removal agent can undergo a further hydrogenation reaction with the hydrogen removed by methanol aromatization under the action of a catalyst, thereby inhibiting the hydrogen transfer reaction and improving the selectivity of aromatics.

(3) The catalyst used is a new catalyst with multifunctional synergistic coupling. The modified zeolite molecular sieve is responsible for the aromatization of methanol to aromatics, and the metal or metal oxide promotes the dehydrogenation reaction in the aromatization process to further improve the selectivity of aromatics.

(4) Since there is a large amount of hydrogen removal reactions in the reaction process, hydrogen can eliminate carbon deposits on the catalyst under reaction conditions, thus improving the reaction life.

(5) The preparation process of the catalyst used is simple and controllable, and it is easy to carry out scale-up preparation.

To sum up, the present invention can obtain high selectivity of aromatic products, good stability and good industrial application prospect.

detailed description

The method for preparing aromatics from methanol with high selectivity provided by the present invention will be further described in detail below, but the present invention is not limited thereto.

Example 1

Weigh 2.0g Cu(NO ₃ ) ₂ ·3H ₂ O, add it into 30g absolute ethanol for ultrasonic dispersion, the time is 4h; weigh 3.0g Zn ion modified H-beta zeolite molecular sieve (Zn content is 0.5wt %), added to the above solution, and continued ultrasonication for 5h; the mixture after ultrasonic dispersion was suction-filtered and washed, and the obtained filter cake was moved to a vacuum drying oven and dried at 80°C for 24h; the obtained sample was moved to a tube furnace, Introduce NO/Ar mixed gas containing 10% NO by volume fraction, heat up to 550°C at a rate of ₂ °C/min and calcinate for 6 hours; The rate is 1°C/min) for 4 hours, and the obtained sample is the catalyst.

Catalytic reactions are carried out in fixed-bed microreactors. Take 1.0 g of the catalyst and heat it from room temperature to 550 °C at a rate of 5 °C/min in a nitrogen atmosphere, and keep it for 60 min. Afterwards, methanol and carbon monoxide (the molar ratio of methanol to carbon monoxide is 10:1) are passed through the catalyst bed under the conditions of reaction pressure 0.5MPa, space velocity 4000h ^-1 , and reaction temperature 500°C for 50h . The reaction products and feed gas were analyzed online by gas chromatography. The specific reaction performance results are listed in Table 1.

Table 1

Note: C _{2-4 refers} to C ₂ -C ₄ hydrocarbons, Aromatics refers to aromatics (benzene and polymethyl-substituted benzene), Other C ₅₊ refers to alkanes and alkenes with carbon number ≥ 5.

Example 2

Weigh 3.5g Fe(NO ₃ ) ₃ 9H ₂ O, add it into 50g water for ultrasonic dispersion for 4 hours; weigh 3.0g Zr ion-modified H-MOR zeolite molecular sieve (Zr content is 0.5wt%), Add it into the above solution and continue ultrasonication for 5h; filter and wash the mixture after ultrasonic dispersion, move the obtained filter cake to a vacuum drying oven and dry at 80°C for 24h; move the obtained sample to a tube furnace, NO/Ar mixed gas with a volume fraction of 10% NO was calcined at a rate of ₂ °C/min to 550°C for 6 hours; the calcined sample was heated at 400°C (heating rate of 1 °C/min) for 4 hours, the obtained sample is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor, and the reaction conditions and product analysis were the same as in Example 1 except that the raw materials were methanol and ethylene (the feed molar ratio was 10:1), and the reaction performance was shown in Table 1.

Example 3

Weigh 3.0g Co(NO ₃ ) ₂ ·6H ₂ O, add it to 45g water and ethanol mixed solution (the mass ratio of water and ethanol is 1:1) for ultrasonic dispersion, the time is 4h; weigh 3.0g Cu ion Modified H-MCM-22 zeolite molecular sieve (Cu content is 0.5wt%) was added to the above solution, and the ultrasonic wave was continued for 5h; Dry at ℃ for 24h; move the obtained sample into a tube furnace, pass through NO/Ar mixed gas containing 10% NO by volume fraction, and heat up to 550℃ at a rate of 2℃/min for calcination for 6h; the calcined sample Using an atmosphere containing 10% H ₂ /Ar to reduce at 400° C. (heating rate 1° C./min) for 4 hours, the obtained sample is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor, except that the raw materials added were methanol and acetaldehyde (feeding molar ratio was 15:1), the reaction conditions and product analysis were the same as in Example 1, and the reaction performance was shown in Table 1.

Example 4

Weigh 5.2g of Zn(NO ₃ ) ₂ ·6H ₂ O, add it into 50g of absolute ethanol for ultrasonic dispersion for 4h; weigh 3.0g of Mo ion-modified H-ZSM-5 zeolite molecular sieve (Mo content is 0.5wt%), added to the above solution, and continued ultrasonication for 5h; the mixture after ultrasonic dispersion was suction filtered and washed, and the resulting filter cake was moved to a vacuum drying oven and dried at 80°C for 24h; the obtained sample was moved to a tube furnace In the interior, the mixed gas of NO/Ar containing 10% NO by volume was introduced, and the temperature was raised to 550°C at a rate of ₂ °C/min for calcination for 6 hours; (The heating rate is 1° C./min) and reduced for 4 hours, and the obtained sample is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor, and the reaction conditions and product analysis were the same as in Example 1 except that the raw materials were methanol and carbon dioxide (the feed molar ratio was 8:1), and the reaction performance was shown in Table 1.

Example 5

Weigh 1.2g PdCl ₂ , add it to 50g water for ultrasonic dispersion for 4 hours; weigh 3.0g Zr ion-modified HY zeolite molecular sieve (Zr content is 0.5wt%), add it to the above solution, and continue ultrasonication for 5 hours; The mixture after ultrasonic dispersion was suction-filtered and washed, and the resulting filter cake was moved to a vacuum drying oven for 24 hours at 80°C; the resulting sample was moved to a tube furnace, and mixed with NO/Ar containing 10% NO by volume gas, heating up to 550°C at a rate of 2°C/min and calcining for 6 hours; reducing the calcined sample at 400°C (heating rate of 1°C/min) in an atmosphere containing 10% H ₂ /Ar for 4 hours, and the obtained sample That is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor, and the reaction conditions and product analysis were the same as in Example 1 except that the raw materials added were methanol and acetylene (the feed molar ratio was 15:1), and the reaction performance was shown in Table 1.

Example 6

Weigh 5.2g NiCl ₂ 6H ₂ O, add it to 50g absolute ethanol for ultrasonic dispersion, the time is 4h; weigh 3.0g Ga ion modified H-SSZ-13 zeolite molecular sieve (Ga content is 0.5wt%) , added to the above solution, and continued to sonicate for 5 hours; the mixture dispersed by sonication was suction filtered and washed, and the obtained filter cake was moved to a vacuum drying oven for 24 hours at 80°C; the obtained sample was moved to a tube furnace and passed through NO/Ar mixed gas containing 10% NO by volume fraction was calcined at 550°C at a rate of ₂ °C/min for 6 hours; the calcined sample was heated at 400°C (heating rate of 1°C/min) for 4 hours, the obtained sample is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor, and the reaction conditions and product analysis were the same as in Example 1 except that the raw materials were methanol and butanone (the feed molar ratio was 10:1), and the reaction performance was shown in Table 1.

Example 7

Weigh 1.8g RuCl ₃ , add it to 30g water for ultrasonic dispersion for 4 hours; weigh 3.0g Cr ion-modified HX zeolite molecular sieve (Cr content is 0.5wt%), add it to the above solution, and continue ultrasonication for 5 hours; The mixture after ultrasonic dispersion was suction-filtered and washed, and the resulting filter cake was moved to a vacuum drying oven for 24 hours at 80°C; the resulting sample was moved to a tube furnace, and mixed with NO/Ar containing 10% NO by volume gas, heating up to 550°C at a rate of 2°C/min and calcining for 6 hours; reducing the calcined sample at 400°C (heating rate of 1°C/min) in an atmosphere containing 10% H ₂ /Ar for 4 hours, and the obtained sample That is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor. The reaction conditions and product analysis were the same as in Example 1. The reaction performance is shown in Table 1.

Example 8

Weigh 1.5g IrCl ₃ , add it to 30g absolute ethanol for ultrasonic dispersion, the time is 4h; weigh 3.0g Mn ion modified H-ZSM-5 zeolite molecular sieve (Mn content is 0.5wt%), add to the above In the solution, continue to sonicate for 5 hours; filter and wash the mixture after ultrasonic dispersion, move the resulting filter cake to a vacuum drying oven and dry at 80°C for 24 hours; move the obtained sample to a tube furnace, and pass through the %NO NO/Ar mixed gas, heated up to 550°C at a rate of ₂ °C/min and calcined for 6 hours; ) under reduction for 4h, the obtained sample is the catalyst.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor. The reaction conditions and product analysis were the same as in Example 2. The reaction performance is shown in Table 1.

Comparative example 1

Catalyst preparation is the same as in Example 4.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor. Except that only methanol was added to the reaction raw materials, the reaction conditions and product analysis were the same as in Example 4. The reaction performance was shown in Table 1.

Comparative example 2

Weigh 1.0g of H-ZSM-5 molecular sieve, and use it as a catalyst through tablet molding.

The catalytic reaction was carried out in a fixed-bed high-pressure microreactor, and the reaction conditions and product analysis were the same as in Example 4. The reaction performance is shown in Table 1.

Claims (10)

1. A method for producing aromatics with methanol high selectivity, characterized in that it may further comprise the steps: 1) catalyst pretreatment, the catalyst is metal oxide/acidic zeolite molecular sieve compound; 2) Catalytic reaction: After the catalyst is pretreated, the reaction raw materials are passed through to form methanol and hydrogen capture-removal agent, and the product aromatics are obtained through solid catalyst bed reaction at a space velocity of 500-10000h ^-1 . 2. a kind of method for producing aromatics with methanol high selectivity as claimed in claim 1, is characterized in that in step 1), the preparation method of described metal oxide/acidic zeolite molecular sieve compound is: (1) adding the salt compound of the metal element into the solvent for ultrasonic dispersion, then adding the modified acidic zeolite molecular sieve, and continuing the ultrasonic dispersion to obtain the mixture; (2) After the mixture obtained in step (1) is suction filtered and washed, the gained filter cake is dried; (3) Calcining and reducing the dried sample in step (2) to obtain the catalyst metal oxide/acidic zeolite molecular sieve composite. 3. a kind of method for producing aromatics with methanol high selectivity as claimed in claim 2, is characterized in that in step 1) in (1) part, the mass ratio of the salt compound of described metal element and solvent is 1:( 0～100); the salt compound is selected from at least one of nitrate, hydrochloride, acetylacetonate, acetate, bromide; the time of the ultrasonic dispersion is 0.5～10h; the continuous ultrasonic The dispersion time is 0.5-10h. 4. A method for producing aromatics with high selectivity from methanol as claimed in claim 2, characterized in that in step 1) part (2), the drying is vacuum drying, the drying temperature is 40-100°C, and the drying The time is 1 ~ 48h. 5. a kind of method for producing aromatics with methanol high selectivity as claimed in claim 2, is characterized in that in step 1) in (3) part, the method for described roasting is: the sample after drying is moved to tube furnace The NO/Ar mixed gas containing NO is used for roasting, the heating rate is 0.5-2°C/min, the temperature is 300-650°C, and the roasting time is 1-24h; the volume percentage of NO in the NO/Ar mixed gas is 5% to 20%; the reduction can be carried out in an atmosphere containing H ₂ , the volume percentage of H ₂ can be 5% to 50%, the heating rate is 0.5 to 5°C/min, and the temperature is 250 to 500°C. The time is 0.5-10 hours. 6. a kind of method for producing aromatics with methanol high selectivity as claimed in claim 1, is characterized in that in step 1), the concrete method of described catalyst pretreatment is: the inertness that catalyst is in nitrogen, argon or helium Heating in gas from room temperature to 300-650°C at a rate not higher than 20°C/min, and keeping it for 10-300min. 7. a kind of method for producing aromatics with methanol high selectivity as claimed in claim 1, is characterized in that in step 2), the mol ratio of methyl alcohol and hydrogen capture-removal agent in described methanol and hydrogen capture-removal agent is (0.05～100): 1; the hydrogen capture-removal agent is selected from at least one of carbon monoxide, carbon dioxide, sulfur dioxide, unsaturated olefins, unsaturated alkynes, nitrogen oxides, aldehyde compounds, and ketone compounds ; The unsaturated olefin is selected from at least one of ethylene, propylene, butene, pentene, and hexene; the unsaturated alkyne is selected from at least one of acetylene, propyne, butyne, and the nitrogen The oxide is selected from at least one of nitric oxide, nitrogen dioxide, and nitrous oxide, and the aldehyde compound is selected from at least one of acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, and benzaldehyde. The ketone compound is selected from at least one of acetone, butanone, pentanone, and cyclohexanone; the unsaturated olefin is selected from at least one of ethylene, propylene, butene, pentene, and hexene; the The unsaturated alkyne is selected from at least one of acetylene, propyne, butyne, the nitrogen oxide is selected from at least one of nitrogen monoxide, nitrogen dioxide, and nitrous oxide, and the aldehyde compound is selected from At least one of acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, and benzaldehyde, and the ketone compound is selected from at least one of acetone, butanone, pentanone, and cyclohexanone. 8. A kind of method for producing aromatics with methanol high selectivity as claimed in claim 1, is characterized in that in step 2), the composition of described solid catalyst is the mixture of metal and modified acidic zeolite molecular sieve, or metal oxide and A mixture of modified acidic zeolite molecular sieves, wherein the mass percentage of metal or metal oxide is 0.5% to 40%, and the rest is modified acidic zeolite molecular sieve; the metal is selected from Cu, Fe, Ni, Co, Ru, Au, Pt , Pd, Ir, Zn, Zr, Ga, Cr, M, Ti, W at least one, the metal oxide is selected from Cu, Fe, Ni, Co, Ru, Au, Pt, Pd, Ir, Zn , Zr, Ga, Cr, M, Ti, W oxide at least one. 9. a kind of method for producing aromatics with methanol high selectivity as claimed in claim 8, is characterized in that described modified acidic zeolite molecule is screened from at least one in Zn, Zr, Mn, Mo, Cu, Cr, Ga The element-modified zeolite molecular sieve, wherein the mass percentage of the modifying element is 0.1%-10.0%, and the rest is acidic zeolite molecular sieve; the reaction temperature is 300-600°C, and the reaction pressure is 0.1-5.0MPa. 10. The method for preparing aromatics with high selectivity of methanol as claimed in claim 9, characterized in that the method for modifying adopts an ion exchange method.