WO2007014534A1

WO2007014534A1 - Process for synthesis of dimethyl ether by catalytic distillation from methanol

Info

Publication number: WO2007014534A1
Application number: PCT/CN2006/001965
Authority: WO
Inventors: Zhongmin Liu; Xinde Sun; Shukui Zhu; Lei Xu; Zhihui Lv; Shuanghe Meng
Original assignee: Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences
Priority date: 2005-08-04
Filing date: 2006-08-04
Publication date: 2007-02-08
Also published as: CN1907932B; CN1907932A

Abstract

A process for synthesis of dimethyl ether by dehydration of methanol is disclosed. The process comprises the following steps: methanol in the material containing methanol produces mixtures of dimethyl ether and water by being dehydrated in the presence of solid acid catalyst, and the obtained mixtures are distillated to separate dimethyl ether, in which said dehydration and distillation are carried out in catalytic distillation column, and said catalytic distillation column includes tower bottom, stripping section, reacting section, rectifying section and reflux condenser in tower top in order of down-to-up. The reactive section is filled with catalytic distillation element comprising solid acid catalyst, or is alternately installed with distillation tray and catalyst bed.

Description

Catalytic distillation method for producing dimethyl ether from methanol

Technical field

The present invention relates to a process for producing dimethyl ether from methanol, and more particularly to a process for dehydrating methanol in a catalytic distillation column to produce dimethyl ether in the presence of a solid acid catalyst. Background technique

Dimethyl ether is a versatile chemical product that can be synthesized by one-step synthesis of methanol dehydration and synthesis gas. The methanol dehydration method first used sulfuric acid as a catalyst, and the reaction was carried out in the liquid phase. The main disadvantages were serious equipment corrosion and environmental pollution. In the current industrial production, a method for producing dimethyl ether by vapor phase dehydration of methanol using a solid acid catalyst has become a main production method.

U.S. Patent No. 6,674,783 discloses a molecular sieve catalyst for the production of dimethyl ether from methanol. The protons on the molecular sieve catalyst are replaced by metals or amines, and the methanol vapor is subjected to a dehydration reaction on a molecular sieve catalyst.

Chinese patent CN 1036199A discloses a method for producing dimethyl ether from methanol. The methanol vapor is dehydrated on a γ-alumina catalyst containing a small amount of silica, and the dehydrated product is sent to a rectification column for rectification, pure dimethyl The ether and impurities are separately produced as side product on a certain tray of the column.

Chinese patent CN 1125216 discloses a method for producing dimethyl ether from methanol, wherein a content of 72 to 99.9% of methanol is subjected to a gas phase catalytic dehydration reaction in a multistage chilled reactor after removing bismuth and impurities by a gasification separation column. The composite solid acid catalyst containing γ-alumina and aluminosilicate crystals has a reaction temperature of 190-380 ° C and a methanol conversion rate of ~78%.

Chinese patent CN 1322704 discloses a method for producing dimethyl ether from methanol by using a liquid composite acid composed of sulfuric acid and phosphoric acid as a catalyst, which destroys the azeotropy of water and water when a single sulfuric acid is used as a catalyst, and overcomes the single sulfuric acid. When the catalyst is not easy to be distilled out, the acidity in the gas phase is large, and the corrosion problem of the equipment is reduced. The methanol vapor is subjected to a dehydration reaction by contacting the liquid composite acid catalyst at a reaction temperature of 130 to 180 Torr and a reaction pressure of 0 to 0.03 MPa, and the reaction mixture is simultaneously vaporized in the reactor to be separated from the catalyst.

Chinese Patent Publication No. CN 1073979C discloses a method for producing and recovering dimethyl ether from methanol, that is, when unreacted methanol is separated from water rectification to recycle, the molar ratio of water to methanol in the recycled material is 0.8 to 1 The load of the unreacted methanol distillation process can be significantly reduced, and the fresh methanol feedstock can also contain 3 to 10% by weight of water while maintaining a methanol conversion rate of 76% or more. Chinese patent CN 1111231 discloses a method for preparing dimethyl ether by catalytic distillation. The catalytic distillation column is composed of a reaction kettle and a rectification column. The reaction vessel is filled with sulfuric acid having a concentration of 20 to 98% by weight as a catalyst, and the methanol is fed at a position of the fifth theoretical plate number of the rectification column at 100. Dehydration reaction is carried out at a reaction temperature of ~150 ° C and a reaction pressure of 0.05 to 0.15 MPa absolute, and heavy components such as methyl hydrogen sulfate and dimethyl sulfate are concentrated in the lower portion of the column, and continue in the reaction vessel. The methanol reaction forms a chemical equilibrium, and the light component dimethyl ether, unreacted methanol and water are concentrated in the upper part of the column, thereby inhibiting the formation of by-products and improving the selectivity of dimethyl ether. The single pass conversion of methanol is 69. ~ 78%.

Chinese Patent Authorization Publication Nos. CN 1043739C, 1047105C, 1085647C and Chinese Patent Publication No. CN 1199038, etc., disclose a catalyst and a method for directly converting synthesis gas into dimethyl ether, which are prepared by mixing an industrial synthetic methanol catalyst with an acidic component catalyst. The composite catalyst has a reaction temperature of 200 to 400 Torr, a reaction pressure of 2 to 5 MPa, a carbon monoxide conversion rate of 90%, and a dimethyl ether selectivity of 90% or more.

In the above invention, the use of a liquid acid such as sulfuric acid as a catalyst causes problems of equipment corrosion and environmental pollution, and it is difficult to obtain a dimethyl ether product of ruthenium purity by directly synthesizing dimethyl ether from a synthesis gas. Using a solid acid catalyst to dehydrate dimethyl ether from methanol to obtain dimethyl ether with a purity of 99.9%, but the reaction temperature is higher, generally 200~380 ° C, and the conversion per pass is about 70~80%. There is also a certain degree of purity. When the water content of the methanol reaction raw material is high, the single-pass conversion rate is inevitably lowered, and the higher reaction temperature is unfavorable to the stability of the catalyst. Regardless of the use of liquid acid or solid acid catalyst, in the existing method of dehydrating methanol to produce dimethyl ether, methanol cannot be completely converted in one reactor due to chemical equilibrium limitation, and the reaction mixture needs to be in two other distillation columns. The dimethyl ether product, unreacted methanol and water are separated, and the separated methanol is recycled to the reactor. Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a catalytic distillation process for producing dimethyl ether from methanol in one or two apparatuses, thereby greatly reducing equipment investment and operating costs.

The inventors of the present invention have found through intensive studies that the dehydration reaction of methanol and the rectification of dimethyl ether can be carried out in a catalytic rectification column, thereby leading to the completion of the present invention.

In particular, the present invention provides the following:

A method for producing dimethyl ether by dehydration of methanol, the method comprising the steps of:

In the presence of a solid acid catalyst, the methanol in the methanol-containing material is dehydrated to produce a mixture comprising dimethyl ether and water;

Distilling the resulting mixture to separate dimethyl ether and water; The dehydration reaction and the distillation are carried out in a catalytic distillation column, which comprises, in order from bottom to top, a column reactor, a tidying section, a reaction section, a rectifying section and an overhead condensing refluxer, wherein The reaction section is filled with a catalytic distillation element comprising a solid acid catalyst, or alternately arranged with a distillation tray and a catalyst bed.

2. The method according to item 1, wherein the catalytic distillation tower is heated by direct steam heating. 3. The method according to item 1, wherein the methanol-containing material has a methanol content of 5 to 99.99% by weight.

4. The method according to item 3, wherein the methanol-containing material is a liquid phase crude methanol material obtained by condensation and gas-liquid separation of the material flowing out of the synthetic methanol reactor when synthesizing methanol.

5. The method of item 1, wherein the side line is taken from a position of the rectifying section below the overhead condenser to obtain a main dimethyl ether-containing stream, wherein the position of the leading side line is in the material containing methanol Above the feed position.

6. The method of item 1, wherein the catalytic distillation column is operated under the following operating conditions: a pressure of 0.6~

5.0 MPa, the temperature at the top of the column is 30 to 120 ° C, the temperature in the middle of the reaction section is 120 to 220 ° C, the temperature in the column is 160 to 270 ° C, the reflux ratio is 3 to 30, and the feed volume is 0.1 to 10 ML methanol / (ml catalyst > hour).

7. The method of item 1, wherein the solid acid catalyst is an acidic cation exchange resin.

8. The method according to item 1, wherein the solid acid catalyst comprises a compound selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, Y, mordenite, zeolite beta, MCM-22, MCM. -41, MCM-56, MCM-49,

A catalyst for one or more molecular sieves of SAPO-5, SAPO-11 and SAPO-34.

9. The method of item 1, wherein the solid acid catalyst is an alumina catalyst or a catalyst comprising a heteropolyacid or a heteropolyacid salt.

10. The method according to item 1, wherein the theoretical number of the fine distillation section of the catalytic distillation column is: 5 to 40; and the theoretical number of the stripping section is 5 to 50. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic flow diagram of a first mode of operation in which methanol is nearly completely converted in a catalytic distillation column in accordance with the present invention;

2 is a schematic flow diagram of a second mode of operation for partial conversion of methanol in a catalytic distillation column in accordance with the present invention. detailed description

The technical proposal of the present invention is to carry out dehydration reaction of methanol in a catalytic distillation column to produce dimethyl ether in the presence of a solid acid catalyst, and simultaneously perform distillation separation of dimethyl ether, methanol and water. The catalytic distillation column comprises, in order from bottom to top, a column reactor, a stripping section, a reaction section, a fine enthalpy section and an overhead condensing refluxer, wherein The stage is filled with a catalytic distillation element comprising a solid acid catalyst, or alternately arranged with a distillation tray and a catalyst bed. The rectification section of the catalytic distillation column is located between the reaction section and the overhead condensing reflux unit, and the stripping section is located between the reaction section and the column reactor.

The material containing methanol is fed from the bottom of the rectifying section, the reaction section, a position of the stripping section or more than one location. The column reactor of the catalytic distillation column may be provided with any form of reboiler. When the water content of the column discharge material is 99% by weight or more, direct steaming may be employed, thereby eliminating the reboiler.

The materials in the catalytic distillation column mainly include methanol, dimethyl ether and water, wherein dimethyl ether has the highest volatility and the lowest volatility of water. Therefore, the reaction product dimethyl ether and water will leave the reaction section in time under distillation, and are respectively concentrated to the top of the column and the column, and a higher purity dimethyl ether product stream can be obtained from the top of the column, and the reaction is discharged from the column reactor. Water and the water brought in by the raw material methanol; and methanol is enriched in the reaction section in the middle of the catalytic distillation column, so that the methanol concentration is always maintained in the reaction section, and the high methanol dehydration reaction rate is maintained, thereby breaking the chemical equilibrium limit. , a methanol conversion rate higher than that of a general fixed bed reactor is obtained.

In the catalytic distillation column, the catalyst is surrounded by the liquid phase reaction mixture, and the reaction proceeds in the liquid phase, and the formed dimethyl ether forms a gas phase leaving the catalyst when it exceeds a saturated concentration. Since the boiling point of dimethyl ether is much lower than that of methanol and water, dimethyl ether is enriched in the gas phase in a gas-liquid mixed state, and the concentration of dimethyl ether in the liquid phase reaction mixture on the surface of the catalyst is very low. Since the carbon deposit on the surface of the catalyst mainly comes from the hydrocarbon by-product formed by dimethyl ether, dimethyl ether is enriched in the gas phase, which greatly slows down the carbon deposition rate of the catalyst, and the carbonaceous material has a carbon deposition precursor on the catalyst surface. A certain dissolution and scouring action, and thus the life of the catalyst is significantly prolonged compared with the gas phase method.

Another advantage of using the catalytic distillation reaction method is that the reaction heat of the methanol dehydration reaction is directly used for the rectification separation of the materials in the column, and is fully utilized, and eliminates the exothermic reaction due to the reaction in the general fixed bed reaction method. "hot spot".

The catalytic distillation column can be operated in two ways.

Figure 1 is a schematic flow diagram of a first mode of operation in which methanol is nearly completely converted in a catalytic distillation column. The catalytic distillation column is divided into three parts, from top to bottom, respectively, the fine enthalpy section, the reaction section and the stripping section; the top of the tower is produced with dimethyl ether product, and the tower kettle discharges water having a methanol content of less than 0.5% by weight; methanol The feed location of the feedstock is only marked with two locations to account for the difference in methanol feed positions for different concentrations. The actual feed position can vary depending on the methanol content.

In the first mode, the number of theoretical plates in the rectification section and the stripping section is sufficient. Under a certain methanol feed space velocity and the corresponding catalytic distillation column operating conditions, methanol is nearly completely converted in the catalytic distillation column.

In this way, the number of theoretical plates in the rectification section should be sufficient to achieve the desired purity of the overhead dimethyl ether product while maintaining a lower concentration of dimethyl ether in the reaction zone to facilitate the reaction zone. The methanol concentration increases the reaction rate. The number of theoretical plates of the rectifying section is usually 5 to 40, preferably 8 to 20. The theoretical number of stripping sections should be such that the amount of methanol in the water discharged from the column is sufficiently low, such as less than 0.5% by weight or less, to minimize the loss of methanol feedstock while maintaining a lower water concentration in the reaction zone. Thereby, it is advantageous to increase the methanol concentration in the reaction section and increase the reaction rate. The number of theoretical plates in the stripping section is usually 5 to 50, preferably 10 to 30. The trace amount of methanol contained in the water discharged from the tower is not recovered.

The top reflux ratio can be 3 to 30. The dimethyl ether and methanol should be effectively separated in the rectification section to ensure the purity of the dimethyl ether product meets the requirements. At the same time, the methanol and water should be separated in the tanning section to ensure better separation. The methanol content in the water is less than 0.5 weight to avoid excessive loss of methanol while maintaining a high methanol content in the reaction zone. Operating at a higher reflux ratio can reduce the height of the rectification section and the stripping section of the catalytic distillation column, and reduce equipment investment, but increases operating costs and requires a trade-off between the two.

Figure 2 is a schematic flow diagram of a second mode of operation for partial conversion of methanol in a catalytic distillation column. The catalytic distillation column is divided into three parts, from top to bottom, respectively, a fine section, a reaction section and a lifting section, wherein the number of theoretical plates of the stripping section is less than that of the first mode illustrated in Fig. 2; catalytic distillation The tartar product is extracted from the top of the column, and the column is discharged with water having a methanol content of 5 to 50% by weight and a dimethyl ether content of less than 1% by weight, and is introduced into a conventional atmospheric distillation column; an atmospheric distillation column The kettle discharges water having a methanol content of less than 0.5% by weight, and the top of the column produces methanol in an amount of more than 90% by weight and returns to the catalytic distillation column from the upper portion of the reaction section.

"High concentration methanol" means 85 to 99.99% by weight of methanol, and the feeding position thereof is not limited to the position indicated in the drawing, and may be a position of the catalytic distillation column reaction section or the bottom of the rectifying section. "Low concentration methanol 1" means a methanol feedstock having a concentration higher than the methanol concentration in the catalytic distillation column bottoms and less than 90% by weight, which can be fed from a certain point in the catalytic distillation column. "Low concentration methanol 2" means a methanol feedstock having a concentration higher than 5% by weight and lower than the methanol concentration in the catalyst distillation column bottoms, and can be fed from a position of a conventional atmospheric pressure steaming tower.

The second way is that the number of theoretical plates in the stripping section is less than that in the first mode described above. Most of the methanol is converted to dimethyl ether and water in the catalytic distillation column, and unreacted methanol and water are used together from catalytic distillation. After the column of the column is discharged, it is passed to a conventional atmospheric distillation column to separate the water, and the unreacted methanol is separated and returned to the catalytic distillation column to continue the reaction.

The advantage of this mode of operation is that when the operation of the catalytic distillation column fluctuates, the operating conditions can be changed to ensure the purity of the overhead dimethyl ether product without having to take into account the changes in the composition of the catalytic distillation column, in the catalytic distillation column. When the composition of the material changes, the parameters such as the feeding position and the reflux ratio of the atmospheric distillation column can be adjusted to ensure the stability of the composition of the top and the bottom of the column, so that the operation flexibility of the whole device is relatively large. At the same time, since the relative volatility of methanol relative to water under high temperature pressure is smaller than that under normal pressure, the high separation of water and methanol in the atmospheric distillation column with lower manufacturing cost is performed in the catalytic distillation column of the pressurized operation. It's easier. The number of theoretical plates in the rectification section of the catalytic distillation column should be sufficient to achieve the desired purity of the overhead dimethyl ether product, while maintaining a lower concentration of dimethyl ether in the reaction zone to facilitate increasing the methanol concentration in the reaction zone. Improve the reaction speed. The theoretical number of plates in the rectifying section is usually 5 to 40, preferably 8 to 20.

The theoretical number of plates in the stripping section of the catalytic distillation column should be such that the content of methanol in the water discharged from the column is 5 to 50% by weight and the content of dimethyl ether is less than 1% by weight, while maintaining a low water concentration in the reaction section. It is beneficial to increase the methanol concentration in the reaction section and increase the reaction rate. The number of theoretical plates in the stripping section is usually from 3 to 30, preferably from 5 to 15.

The reflux ratio of the catalytic distillation tower can be 3 to 30. The dimethyl ether and methanol should be effectively separated in the rectification section to ensure the purity of the dimethyl ether product meets the requirements. At the same time, the methanol and water should be separated in the stripping section to ensure a certain separation effect. The content of methanol and dimethyl ether meets the above requirements. Operating at a higher reflux ratio can reduce the height of the rectification section and the stripping section of the catalytic distillation column, reducing equipment investment, but increasing operating costs requires a trade-off between the two.

The theoretical atmospheric plate of the conventional atmospheric distillation column described above has a theoretical plate number of 10 to 30, and is operated at a reflux ratio of 0.5 to 8 at the top of the column, so that the content of methanol in the water discharged from the column is less than 0.5% by weight. The methanol content of the stream is higher than 90% by weight. The overhead production stream can be fed from the upper portion of the catalytic distillation column reaction section.

In the reaction process of dehydration of methanol to dimethyl ether, especially at the end of the catalyst, a very small amount of carbon monoxide, carbon dioxide and hydrogen may be generated. In order to obtain a higher purity dimethyl ether product, in the above two modes of operation, The side line can be drawn from a position of the rectifying section below the top condenser of the catalytic distillation column to obtain a dimethyl ether product stream of ruthenium purity. If the methanol-containing material is fed from the rectification section, the position of the lead-out line is above the feed position.

Another significant advantage of using the catalytic distillation reaction method is that methanol in an amount of 5 to 99.99% by weight can be used as a reaction raw material without significantly reducing the methanol treatment amount per unit amount of the catalyst. The use of low concentrations of methanol as a raw material saves the cost of purifying methanol. In the first mode of operation described above, 5 to 90% by weight of the low concentration methanol can be fed from a position in the stripping section (as shown in "low concentration methanol" in Figure 1) to maintain the reaction. The high concentration of methanol in the section; 85~99.99% by weight of the high concentration methanol can be fed from a certain position in the reaction section or the rectification section (as shown in "high concentration methanol" in Fig. 1). When using the second mode of operation described above, the methanol feedstock having a concentration of less than 5% by weight and less than the methanol concentration in the catalytic distillation column column material can be fed from a position of the conventional atmospheric distillation column. (As shown in "Low-concentration methanol 2" in Figure 2), the concentration of methanol in the distillation column of the catalytic distillation column and less than 90% by weight of the methanol feedstock can be taken from a certain position in the stripping section of the catalytic distillation column. Material (as shown in "low concentration methanol 1" in Figure 2); 85~99.99% by weight of high concentration methanol can be fed from a catalytic distillation column reaction section or a rectification section (as shown in Figure 2) "High concentration of methanol" is shown). A special case is to use a liquid phase crude methanol material obtained by condensing and gas-liquid separation of a material flowing out of a reactor for synthesizing methanol as a feed of a catalytic distillation column, thereby eliminating the purification of the existing methanol production method. The rectification tower required for methanol saves investment and operating costs and reduces production costs.

The solid acid catalyst referred to in the present invention may be an acidic cation exchange resin, a solid acid catalyst containing a molecular sieve, an alumina catalyst, or a catalyst containing a heteropoly acid or a heteropolyacid salt.

The molecular sieve may be ZSM-5, ZSM-1 ZSM-22, ZSM-23, Y, mordenite, β zeolite, MCM-22s MCM-4K MCM-56, MCM-49, SAPO-5, SAPO-1K One or more mixtures of molecular sieves such as SAPO-34, especially MCM-22, ZSM-5 or beta zeolite. For industrial application, the molecular sieve may be kneaded with a suitable binder, wherein the molecular sieve has a content of 50 to 95% (dry basis weight) and a binder content of 5 to 50% (dry basis weight). The binder is usually alumina.

The operating conditions of the catalytic distillation column are as follows: the temperature in the middle of the reaction section is maintained at 120~220 ° C, the temperature at the top of the column is 30 to 120 ° C, the temperature in the column is 160 to 270 ° C, and the operating pressure is 0.6 to 5.0 MPa (gauge pressure). The reflux ratio of the overhead is 3 to 30, and the feed volumetric space velocity is 0.1 to 10 ml of methanol / (ml of catalyst, hour).

When using an acidic cation exchange resin as a catalyst, since the resin catalyst is not resistant to high temperatures, the temperature of the reaction zone should not be higher than the maximum allowable temperature of the resin catalyst used, and should not be ultra high 17 (TC, corresponding catalytic distillation column operation). The conditions are as follows: the temperature in the middle of the reaction section is maintained at 120~170 ° C, the temperature at the top of the column is 30 to 85 ° C, the temperature in the column is 160 to 224 ° C, the operating pressure is 0.6 to 2.4 MPa (gauge pressure), and the top is refluxed. The ratio is 3 to 30, and the feed volume has a space velocity of 0.1 to 0 ml of methanol / (ml of catalyst, hour).

With the catalytic distillation method and catalyst of the present invention, under the corresponding reaction conditions, substantially no hydrocarbon by-products are produced in the reaction, and the selectivity of dimethyl ether is close to 100%. Example

The following are examples of the invention, but the invention is not limited to the following examples. Example 1

Catalytic Distillation of Methanol to Dimethyl Ether

198 g of MCM-22 zeolite raw powder (Si0 ₂ /Al ₂ 0 ₃ is 26, the base content is 77% by weight) and 97.2 g of SB powder (a kind of pseudo-boehmite imported from Germany, the dry content of 71.2% by weight And 5.4 grams of tianjing powder mixed evenly, adding 240ml of 10% by weight of dilute nitric acid and deionized water, extruded into strips, made into a strip shape of 1.6 mm in diameter, dried at 120 Torr for 2 hours, and calcined at 540 ° C in a Mafu furnace. 3 hours, then use a total of 4500 ml of 0.8 M aqueous NH ₄ N0 ₃ solution It is exchanged 3 times at 85 ° C, washed 3 times with deionized water, dried at 120 ° C for 4 hours, calcined at 530 ° C for 2 hours, then treated with steam at 300 ° C for 2 hours, and twisted into 4 to 6 mm long. Strip catalyst.

The catalytic distillation column comprises an overhead condensing reflux reactor, a rectifying section, a reaction section, a stripping section and a column reactor. The inner diameter of the tower body is 25 mm, and the effective height of the reaction section is 1 m. 98 ml of the above catalyst is mixed with 392 ml of Φ4χ4 mm stainless steel mesh ring and uniformly charged into the reaction section, which is equivalent to about 24 theoretical plates; the rectifying section and the stripping section The effective twist is 0.5 m, and the Φ3Χ3 mm stainless steel mesh ring is loaded, which is equivalent to about 20 theoretical plates. The tower kettle is heated by a tubular resistance furnace.

Industrial methanol with a purity of 99% by weight is used as a reaction raw material, and is fed between the reaction section and the rectifying section. The operating pressure in the catalytic distillation column is 2.8 MPa, the feed temperature is 160 ° C, and the temperature in the middle of the reaction section is about Under the operating conditions of 183 ° C, overhead reflux ratio of 12 and methanol feed of 200 ml methanol / hr, the methanol conversion was 99.88%, the dimethyl ether selectivity was 100%, and the dimethyl ether purity was greater than 99.9% by weight, the methanol content in the bottom water of the column was 0.43% by weight, and dimethyl ether was not detected. Example 2

Catalytic Distillation of Methanol to Dimethyl Ether

175.4 g of ammonium ZSM-5 zeolite raw powder (Si0 ₂ /Al ₂ 0 ₃ is 38, dry content of 92.8 wt%, produced by Tianjin University Catalyst Factory) and 59.2 g of pseudo-boehmite (produced by Shandong Aluminum Co., Ltd.) The dry content of 68.7 wt%) and 5.0 g of the phthalocyanine powder were uniformly mixed, and 96 ml of 5% by weight of dilute nitric acid and deionized water were added to form a strip of 2 mm in diameter and dried at 120 ° C for 2 hours. It was calcined in a muffle furnace at 550 ° C for 3 hours, and then treated with 400 Torr of steam for 2 hours, and kneaded into a strip catalyst of 4 to 6 mm in length.

The catalytic distillation column comprises an overhead condensing reflux reactor, a rectifying section, a reaction section, a lifting section and a tower kettle. The inner diameter of the tower body is 25 mm, and the effective height of the reaction section is 1 m. 98 ml of the above catalyst is mixed with 392 ml of Φ4χ4 mm stainless steel mesh ring and uniformly charged into the reaction section, which is equivalent to about 24 theoretical plates; the fine section and the stripping section The effective height is 0.5 m, and the Φ3χ3 mm stainless steel mesh ring is loaded, which is equivalent to about 20 theoretical plates. The tower kettle is heated by a tubular resistance furnace.

Industrial methanol with a purity of 99% by weight is used as a reaction raw material, and is fed between the reaction section and the rectifying section. The operating pressure in the catalytic distillation column is 2.0 MPa, the feed temperature is 150 ° C, and the temperature in the middle of the reaction section is about Under the operating conditions of 168 Torr, an overhead reflux ratio of 18, and a methanol feed of 90 ml of methanol per hour, the methanol conversion was 99.9%, the dimethyl ether selectivity was 100%, and the dimethyl ether purity was greater than 99.9. %, the methanol content in the bottom water of the tower was 0.36% by weight, and dimethyl ether was not detected. Example 3 Catalytic distillation of methanol to dehydrate to form dimethyl ether

The catalytic distillation column comprises an overhead condensing reflux reactor, a rectifying section, a reaction section, a stripping section and a column reactor. The inner diameter of the tower is 50 mm, the effective length of the reaction section is 1 m, and 390 ml of commercially available D005 macroporous strong acid resin catalyst (produced by Hebei Kerry Chemical Co., Ltd., with a specific surface area of 15 m ² /g, specific pore volume of 0.056 ml/g). , exchange capacity 1.3 mol / D into the glass cloth sewing small bag, each glass cloth small bag with 5 ~ 7 ml of resin, and then mixed with 1570 ml Φ5 χ 5 mm stainless steel mesh ring and then loaded into the reaction section, about equivalent 20 theoretical plates; the effective height of the rectifying section and the stripping section are both 0.6 m, and the Φ3Χ3 mm stainless steel mesh ring is filled, which is equivalent to about 24 theoretical plates. The tower kettle is heated by a tubular resistance furnace.

The industrial methanol with a purity of 99% by weight is used as a reaction raw material, and is fed between the reaction section and the rectifying section. The operating pressure in the catalytic distillation column is 1.0 MPa, the reflux ratio at the top of the column is 22, and the feed temperature is 110 °C. In the middle of the reaction section, the temperature is about 130 ° C, and the methanol feed rate is 234 ml of methanol per hour. The methanol conversion rate is 99.86 § %, the dimethyl ether selectivity is 100%, and the dimethyl ether purity is More than 99.9% by weight, the methanol content in the bottom water of the column was 0.48% by weight, and dimethyl ether was not detected. Example 4

Catalytic distillation of methanol to dehydrate to form dimethyl ether

The catalytic distillation column comprises an overhead condensing reflux unit, a rectifying section, a reaction section, a stripping section and a column reactor. The inner diameter of the tower body is 50 mm, the effective height of the reaction section is 1 m, and 390 ml of commercially available D005 macroporous strong acid resin catalyst (produced by Hebei Kerry Chemical Co., Ltd.) has a specific surface area of 15 m ² /g and a specific pore volume of 0.056 ml/g. Exchange capacity 1.3 mol / 1) into a small bag of glass cloth sewing, each glass cloth pouch with 5 ~ 7 ml of resin, and then mixed with 1570 ml Φ5 χ 5 mm stainless steel mesh ring and then loaded into the reaction section, about equivalent In 20 theoretical plates; the effective twist of the rectifying section and the stripping section are both 0.6 m, and the Φ3χ3 mm stainless steel mesh ring is filled, which is equivalent to about 24 theoretical plates. The tower kettle is heated by a tubular resistance furnace.

Industrial methanol with a purity of 97.5% by weight is used as a reaction raw material, and is fed between the reaction section and the rectifying section. The operating pressure in the catalytic distillation column is 1.8 MPa, the feed temperature is 135 ° C, and the temperature in the middle of the reaction section is about Under the operating conditions of 158 ° C, reflux at the top of the column, and methanol feed rate of 700 ml methanol / hr, the methanol conversion rate is 99.9%, the dimethyl ether selectivity is 100%, and the dimethyl ether purity is greater than 99.9 wt%, the methanol content in the bottom water of the column was 0.35 wt%, and dimethyl ether was not detected. Example 5 Catalytic Distillation of Methanol to Dimethyl Ether

175.4 g of ammonium type ZSM-5 zeolite raw powder (Si0 ₂ /Al ₂ 03 is 38, dry content of 92.8 wt%, produced by Tianjin University Catalyst Factory) and 59.2 g of pseudo-boehmite (produced by Shandong Aluminum Co., Ltd., dry) The base content is 68.7 wt%) and 5.0 g of the phthalocyanine powder is uniformly mixed. 96 ml of 5% by weight of dilute nitric acid and deionized water are added, and extruded into strips to form a strip shape of 2 mm in diameter, dried at 120 Torr for 2 hours, in a Mafu furnace. The 550 Ό was calcined for 3 hours, and then treated with steam at 400 ° C for 2 hours to form a strip catalyst of 4 to 6 mm length.

The catalytic distillation column comprises an overhead condensing reflux unit, a finishing section, a reaction section, a stripping section and a column reactor. The inner diameter of the tower body is 25 mm, and the effective height of the reaction section is 1 m. 98 ml of the above catalyst is mixed with 392 ml of Φ4χ4 mm stainless steel mesh ring and uniformly charged into the reaction section, which is equivalent to about 24 theoretical plates; the rectifying section and the stripping section The effective height is 0.5 m, and the Φ3χ3 mm stainless steel mesh ring is loaded, which is equivalent to about 20 theoretical plates. The tower kettle is heated by a tubular resistance furnace.

Industrial methanol with a purity of 99% by weight and deionized water were mixed into a methanol aqueous solution having a purity of 75% by weight as a reaction raw material, and fed from the top of the stripping section to the bottom 10 cm, and the operating pressure of the catalytic distillation column was 1.8 MPa. The feed temperature M4 C, the temperature in the middle of the reaction section is about 164 ° C, the reflux ratio at the top of the column is 25, and the methanol feed rate is 80 ml methanol / hour. The methanol conversion rate is 99.7%, dimethyl ether. The selectivity was 100%, the purity of the overhead dimethyl ether was more than 99.9% by weight, the methanol content in the effluent water of the column was 0.38% by weight, and dimethyl ether was not detected. Example 6

Catalytic Distillation of Methanol to Dimethyl Ether

175.4 g of ammonium ZSM-5 zeolite raw powder (Si0 ₂ /Al ₂ 0 ₃ is 38, dry content of 92.8 wt%, produced by Tianjin University Catalyst Factory) and 59.2 g of pseudo-boehmite (produced by Shandong Aluminum Co., Ltd.) The dry content of 68.7 wt%) and 5.0 g of the phthalocyanine powder were uniformly mixed, and 96 ml of 5% by weight of dilute nitric acid and deionized water were added to form a strip of 2 mm in diameter, and 12 (TC dry for 2 hours). It was calcined in a muffle furnace at 550 ° C for 3 hours, and then treated with 400 Torr of steam for 2 hours, and kneaded into a strip catalyst of 4 to 6 mm in length.

The catalytic distillation column comprises an overhead condensing reflux reactor, a rectifying section, a reaction section, a stripping section and a column reactor. The inner diameter of the tower body is 25 mm, and the effective height of the reaction section is 1 m. 98 ml of the above catalyst is mixed with 392 ml of Φ4χ4 mm stainless steel mesh ring and uniformly charged into the reaction section, which is equivalent to about 24 theoretical plates; the fine section and the stripping section The effective height is 0.5 m, and the Φ3χ3 mm stainless steel mesh ring is loaded, which is equivalent to about 20 theoretical plates. The tower kettle is heated by a tubular resistance furnace.

Industrial methanol with a purity of 99% by weight and deionized water were mixed into a methanol aqueous solution having a purity of 15% by weight as a reaction raw material, and fed 15 cm below the top of the stripping section, and the operating pressure in the catalytic distillation column was 2.3 MPa. Feeding. Temperature 155 ° C, the temperature in the middle of the reaction section is about 173 Ό, the reflux ratio at the top of the column is 23, and the methanol feed amount is 100 ml. Under methanol/hour operating conditions, the methanol conversion was 99.0%, the dimethyl ether selectivity was 100%, the dimethyl ether purity was greater than 99.9% by weight, and the methanol content in the effluent from the column was 0.15 wt%. Check out.

Claims

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Distilling the resulting mixture to separate dimethyl ether;

The dehydration reaction and distillation are carried out in a catalytic distillation column, and the catalytic distillation column comprises, in order from bottom to top, a column reactor, a stripping section, a 'reaction section, a rectifying section, and a column top condensing reflux unit. The reaction section is filled with a catalytic distillation element comprising a solid acid catalyst, or alternately arranged with a distillation tray and a catalyst bed.

The method according to claim 1, wherein the catalytic distillation column is heated by direct steam heating.

3. The method according to claim 1, wherein the methanol-containing material has a methanol content of 5 to 99.99 by weight ⁰ / ₀ .

4. The method according to claim 3, wherein the methanol-containing material is a liquid phase crude methanol material obtained by condensation and gas-liquid separation of the material flowing out of the synthetic methanol reactor when methanol is synthesized.

5. The method according to claim 1, wherein the side line is taken from a position of the rectifying section below the overhead condenser to obtain a main dimethyl ether-containing stream, wherein the position of the leading side line is in the material containing methanol Above the feed position.

6. The method according to claim 1, wherein the catalytic distillation column is operated under the following operating conditions: a pressure of 0.6 to 5.0 MPa, a temperature at the top of the column of 30 to 12 (TC, a temperature in the middle of the reaction section of 120 to 12). At 220 ° C, the temperature of the column was 160 to 270 ° C, the reflux ratio was 3 to 30, and the feed volume space velocity was 0.1 to 10 ml of methanol / (ml of catalyst - hour).

7. The method of claim 1 wherein said solid acid catalyst is an acidic cation exchange resin.

8. The method of claim 1 wherein said solid acid catalyst comprises a component selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, Y, mordenite, beta zeolite, MCM-22, MCM-4K MCM-56, MCM-49,

A catalyst for one or more molecular sieves of SAPO-5, SAPO-11 and SAPO-34.

9. The method of claim 1 wherein said solid acid catalyst is an alumina catalyst or a catalyst comprising a heteropolyacid or a heteropolyacid salt.

10. The method according to claim 1, wherein the theoretical number of the rectifying section of the catalytic distillation column is 5 to 40; and the theoretical number of the stripping section is 5 to 50.