CN114249648A - Preparation method of methyl acetate - Google Patents

Abstract

The application discloses a preparation method of methyl acetate, which at least comprises the following steps: raw materials containing acetic acid are in contact reaction with a catalyst in a reactor to obtain methyl acetate; the catalyst contains a base or acid modified molecular sieve; the acetic acid is in a gaseous state during the reaction. The preparation method of methyl acetate provided by the application can convert acetic acid into corresponding methyl acetate and carbon monoxide, and convert corrosive impurities into valuable raw materials.

Description

Preparation method of methyl acetate

Technical Field

The application relates to a preparation method of methyl acetate, belonging to the field of chemical material preparation.

Background

Methyl acetate, as a novel basic chemical raw material, has a series of excellent physical properties such as low boiling point, strong dissolving power and no pollution, and is gradually accepted by people. Methyl acetate is becoming a mature product internationally and is used for replacing acetone, butanone, ethyl acetate, cyclopentane and the like. In 2005, eastman in the united states replaced acetone solvent with methyl acetate, which is not a limited organic pollutant emission, and could meet the new environmental standards of paint, ink, resin, and adhesive factories.

Meanwhile, the biomass pyrolysis technology is one of the leading technologies of biomass energy research in the world. The technology can convert biomass mainly comprising waste such as wood chips into high-quality alternative liquid fuel (bio-oil) which is easy to store, transport and use and has high energy density in a continuous process and industrial production mode. However, bio-oil is complex in composition and contains a large amount of acetic acid substances, so that bio-oil is corrosive. Since the main component of the carboxylic acid-based substance is acetic acid, it is important to remove acetic acid. Currently, acetic acid can be removed by two reactions: ketonization and esterification reactions. The esterification reaction requires additional consumption of methanol or dimethyl ether, the ketonization process generates carbon dioxide, which reduces the utilization rate of carbon atoms, and the basic catalyst used in the ketonization process induces the condensation reaction of acetone. By utilizing the method, the acetic acid in the acetic acid can be converted into methyl acetate without adding additional chemical substances, so that the acidity of the acetic acid is reduced; simultaneously, carbon monoxide is recovered, and acetic acid is efficiently utilized.

Disclosure of Invention

The application provides a preparation method of methyl acetate, which takes acetic acid as a raw material and utilizes decarbonylation reaction to realize the preparation of methyl acetate from biomass and the sustainable development of methyl acetate.

According to a first aspect of the present application, there is provided a process for the preparation of methyl acetate, the process comprising at least: raw materials containing acetic acid are in contact reaction with a catalyst in a reactor to obtain methyl acetate;

the catalyst contains a base or acid modified molecular sieve;

the acetic acid is in a gaseous state during the reaction.

Alternatively, the catalyst herein is a solid acid catalyst.

Optionally, the reaction conditions are: the reaction temperature is 300-400 ℃; the reaction pressure is 0.1-0.8 MPa; the mass airspeed of acetic acid in the raw materials is 0.01-10.0 h^-1。

Alternatively, the upper mass space velocity limit of acetic acid in the feed is independently selected from 10.0h^-1、9h^-1、8h^-1、7h^-1、6h^-1、5.0h^-1、4h^-1、3h^-1、2h^-1、1h^-1、0.5h^-1、0.1h^-1、0.05h^-1Lower limit is independently selected from 0.01h^-1、9h^-1、8h^-1、7h^-1、6h^-1、5.0h^-1、4h^-1、3h^-1、2h^-1、1h^-1、0.5h^-1、0.1h^-1、0.05h^-1。

Alternatively, the upper limit of the reaction temperature is independently selected from 400 ℃, 390 ℃, 370 ℃, 350 ℃, 320 ℃, and the lower limit is independently selected from 300 ℃, 370 ℃, 350 ℃, 320 ℃, 390 ℃.

Alternatively, the upper limit of the reaction pressure is independently selected from 0.8MPa, 0.6MPa, 0.4MPa, 0.2MPa, and the lower limit is independently selected from 0.1MPa, 0.6MPa, 0.4MPa, 0.2 MPa.

Preferably, the reaction temperature is 300-360 ℃.

Preferably, the reaction pressure is 0.1 to 0.5 MPa.

Preferably, the mass space velocity of the acetic acid is 0.1-5 h^-1。

Optionally, the volume percentage of acetic acid in the raw material is 0.1-100%.

Optionally, the upper limit of the volume percentage content of the acetic acid in the raw materials is independently selected from 30%, 50%, 70%, 90%, 100%, and the lower limit is independently selected from 0.1%, 1%, 4.1%, 5%, 10%.

Optionally, the feed gas further comprises a diluent gas;

the diluent gas is selected from at least one of hydrogen, nitrogen, helium, argon, and carbon dioxide.

In the application, the adverse effect of the reaction heat on the system can be better relieved by adding the diluent gas, and a person skilled in the art can select whether to add the diluent gas and the type of the diluent gas according to the actual needs and the specific catalyst, and in principle, the gas which does not react with the reactant, the product and the catalyst in the system can be used as the diluent gas. Preferably, the diluent gas is selected from at least one of nitrogen, hydrogen, argon.

Optionally, the volume percentage of the diluent gas in the raw material is 0.01-99.9%.

Optionally, the upper limit of the volume percentage of the diluent gas in the feedstock is independently selected from 99.9%, 80%, 60%, 40%, 20%, 10%, 5%, 1%, 0.5%, and the lower limit is independently selected from 0.01%, 80%, 60%, 40%, 20%, 10%, 5%, 1%, 0.5%.

Preferably, the volume percentage of the diluent gas in the raw material is 10-60%.

Preferably, the alkali or acid modified molecular sieve has a silicon-aluminum atomic ratio of 5-50.

Alternatively, the alkali or acid modified molecular sieve has an upper limit on the silicon to aluminum atomic ratio independently selected from 50, 45, 40, 35, 30, 25, 20, 15 and a lower limit independently selected from 5, 45, 40, 35, 30, 25, 20, 15.

Preferably, the MOR molecular sieve is H-MOR.

Preferably, the atomic ratio Si/Al of H-MOR silicon to aluminum is 5-20.

Optionally, the base is selected from any one of sodium hydroxide and potassium hydroxide;

the acid is selected from any one of nitric acid, ammonium fluoride, oxalic acid and citric acid.

Optionally, the alkali or acid modified molecular sieve contains a binder; the binder is at least one of alumina and silica.

Alternatively, the hydrogen form MOR molecular sieve is prepared by the following method: and exchanging the roasted Na-MOR molecular sieve for 1-3 times by using an ammonium nitrate solution, wherein the exchange is carried out for 1-3 h at the temperature of 70-90 ℃ each time, then washing by using deionized water, and drying to obtain the ammonium type molecular sieve. And roasting the ammonium molecular sieve at 400-600 ℃ for 3-5 h to obtain the hydrogen molecular sieve.

Alternatively, the acid-modified molecular sieve in the present application is prepared by the following method: treating the ammonium molecular sieve in 0.05-1.0mol/L acid solution at 40-90 ℃ for 0.5-2h, washing with deionized water for 1-3 times after treatment, and roasting the modified ammonium molecular sieve at 400-600 ℃ for 3-5 h after drying to obtain the acid-modified hydrogen molecular sieve.

The alkali-modified molecular sieve is prepared by the following method: treating the ammonium type molecular sieve in 0.05-1.0mol/L aqueous alkali for 0.5-2h at 40-90 ℃, washing with deionized water for 1-3 times after the treatment, exchanging with ammonium nitrate solution for 1-3 times again after the alkali treatment, exchanging for 1-3 h at 70-90 ℃ each time, then washing with deionized water, and drying to obtain the ammonium type molecular sieve.

Preferably, the mass content of the binder in the alkali or acid modified molecular sieve is 0.01-80%.

Specifically, the strength of the catalyst is enhanced by adding a binder.

Optionally, the upper limit of the mass content of the binder in the alkali-or acid-modified molecular sieve is independently selected from 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 5%, 1%, 0.05%, and the lower limit is independently selected from 0.01%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 5%, 1%, 0.05%.

Preferably, the binder is alumina, and the content of the alumina is 30-60 wt%.

Optionally, the reactor is a fixed bed reactor.

The beneficial effects that this application can produce include:

(1) the preparation method of methyl acetate provided by the application can convert acetic acid into corresponding methyl acetate and carbon monoxide, and convert corrosive impurities into valuable raw materials.

(2) The preparation method of methyl acetate provided by the application can be used for removing acetic acid in the bio-oil, and the pH value of the bio-oil is improved and the corrosivity of the bio-oil is reduced by converting the acetic acid in the bio-oil.

(3) The catalyst used in the prior decarbonylation reaction is a catalyst taking cobalt, nickel, rhodium, palladium, platinum and other metals or noble metals as active components, and the active component of the catalyst used in the application is solid acid, so that the preparation and use costs of the catalyst are greatly reduced, and methyl acetate is generated with high selectivity.

Detailed Description

Unless otherwise specified, the raw materials and catalysts in the examples of the present application were all purchased commercially.

The analysis method in the examples of the present application is as follows:

the raw materials and the products were detected by Agilent 7890A gas chromatography from Agilent, Inc., using HP-PLOT/Q capillary column from Agilent, Inc.

According to an embodiment of the application, a fixed bed reactor is selected, the filling mass of the catalyst is 0.5-3.0 g, the reaction temperature is 280-400 ℃, and the reaction pressure is 0.1-1 MPa. The raw material carboxylic acid enters a reactor by adopting two sample introduction modes:

the first way is to use inert diluent gas to carry saturated vapor of carboxylic acid in the bubbler into the fixed bed reactor to obtain carboxylic acid raw material gas with different volume contents. The saturated vapor pressure of the raw materials can be adjusted by controlling the temperature of the bubbler, and the saturated vapor pressure of the carboxylic acid can be found on the official website of the national institute of standards and technology. Examples 1-30, 35-50 of the present application were all fed in this manner.

The second mode is that the liquid raw material carboxylic acid is directly pumped into the fixed bed reactor by a constant flow pump at different flow rates, and simultaneously, a certain flow of diluent gas is introduced, and the mass airspeed of the raw material can be adjusted by changing the flow of the constant flow pump. Examples 31-34 of the present application were fed in this manner.

The conversion, selectivity, in the examples of the present application were calculated as follows:

acetic acid conversion rate ═ [ (moles of acetic acid in feed) - (moles of acetic acid in discharge) ]/(moles of acetic acid in feed) × (100%)

Methyl acetate selectivity ═ mole of methyl acetate in product ÷ (sum of moles of all products) × 100%.

1, catalyst preparation:

1.1 preparation of Hydrogen form molecular sieves

H-MOR, i.e., a mordenite catalyst in the hydrogen form. 100 g of calcined Na-MOR molecular sieves (from Nankai catalyst works) having Si/Al atomic ratios of 5, 10,20,30 and 50, respectively, were exchanged with 0.8mol/L ammonium nitrate solution three times at 80 ℃ for 2 hours each time and washed with deionized water. After drying, the mixture was calcined at 500 ℃ for 4 hours. After being extruded and crushed, the catalyst with 40 to 60 meshes is screened for later use and is marked as No. 1, No. 2, No. 3, No. 4 and No. 5 catalysts.

1.2 preparation of sodium hydroxide modified H-MOR molecular sieves

Exchanging 100 g of baked Na-MOR molecular sieve (produced from Nankai catalyst factory) with 5 atomic ratio of silicon and aluminum for three times by 0.8mol/L ammonium nitrate solution at 80 ℃ for 2 hours, washing with deionized water, and drying to obtain NH₄-MOR. 50g of NH₄The MOR was treated with 500ml of 0.1mol/L NaOH solution at 80 ℃ for 1 h. After the treatment, the mixture was washed with deionized water 3 times. NH treated with sodium hydroxide solution₄-MOR was exchanged three more times with 0.8mol/L ammonium nitrate solution, each time for 2 hours at 80 ℃, washed with deionized water and dried. Roasting at 500 ℃ for 4H to obtain H-MOR treated by a sodium hydroxide solution. After being pressed and crushed, the catalyst with 40 to 60 meshes is screened for standby and is marked as No. 6 catalyst.

1.3 preparation of acid-modified H-MOR molecular sieves

Exchanging 100 g of baked Na-MOR molecular sieve (produced from Nankai catalyst factory) with 5 atomic ratio of silicon and aluminum for three times by 0.8mol/L ammonium nitrate solution at 80 ℃ for 2 hours, washing with deionized water, and drying to obtain NH₄-MOR. 50g of NH₄The MOR was treated with 500ml of a 0.1mol/L nitric acid solution at 80 ℃ for 1 h. After the treatment, the mixture was washed 3 times with deionized water and dried. Roasting at 500 ℃ for 4H to obtain the H-MOR treated by the nitric acid solution. After being pressed and crushed, the catalyst with 40 to 60 meshes is screened for standby, and is marked as 7# catalyst.

Ammonium fluoride, oxalic acid and citric acid modified H-MOR were treated in the same manner except for NH₄Ammonium fluoride, oxalic acid and citric acid solutions were used for MOR. The H-MOR obtained finally was designated as catalyst # 8, 9 and 10.

1.4 preparation of citric acid modified H-MOR molecular sieves

100 g of calcined Na-MOR molecular sieve (from Nankai catalyst factory) with Si/Al atomic ratio of 10,20,30 and 50 was exchanged with 0.8mol/L ammonium nitrate solution three times at 80 deg.C each timeExchanging for 2 hours, washing with deionized water, and drying to obtain NH₄-MOR. 50g of NH₄The MOR was treated with 500ml of 0.1mol/L citric acid solution at 80 ℃ for 1 h. After the treatment, the mixture was washed 3 times with deionized water and dried. Roasting at 500 ℃ for 4H to obtain the H-MOR treated by the citric acid solution. After being pressed and crushed, the catalyst with 40 to 60 meshes is screened for later use and is marked as No. 11, No. 12, No. 13 and No. 14 catalysts.

2 catalyst reaction evaluation example

2.1 reactions on different molecular sieves and results

Example 1

1g of 1# molecular sieve catalyst is filled in a fixed bed reactor with the inner diameter of 8 mm, and the catalyst is pre-activated under the condition that N is₂The flow rate is 30ml/min, the temperature is increased to 400 ℃ at the speed of 1 ℃/min, the temperature is kept at 400 ℃ for 2 hours, then the temperature is reduced to the required reaction temperature of 330 ℃ under the nitrogen atmosphere, the reaction pressure is 0.1MPa, and the total mass space velocity of the raw material acetic acid is 0.1h^-1，N₂The flow rate was 20ml/min, and the volume percentage of acetic acid was 3.36%, under the conditions shown in Table 1.

Examples 2 to 14

The reaction conditions were the same as in example 1 except that the catalysts were No. 2-No. 14, respectively, and the reaction results are shown in Table 1.

TABLE 1 results for catalysts for decarbonylation reactions of different molecular sieves and Si/Al ratios

2.3 results of different reaction temperatures

Example 15

1g of No. 10 molecular sieve catalyst is filled in a fixed bed reactor with the inner diameter of 8 mm, and the catalyst is pre-activated under the condition that N is₂A flow rate of 30ml/min, a rate of 1 ℃/min to 400 ℃, andkeeping the temperature at 400 ℃ for 2 hours, then reducing the temperature to 300 ℃ in the nitrogen atmosphere, the reaction pressure is 0.1MPa, and the total mass space velocity of the raw material acetic acid is 0.1 hour^-1，N₂The flow rate was 20ml/min, and the volume percentage of acetic acid was 3.36%, under which the reaction results are shown in Table 2.

Examples 16 to 19

The other conditions were the same as in example 15 except that the reaction temperatures were 330 ℃, 350 ℃, 380 ℃ and 400 ℃, respectively. The reaction results are shown in Table 2.

TABLE 2 results of decarbonylation reactions at different reaction temperatures

2.4 results of different reaction pressures

Example 20

1g of No. 10 molecular sieve catalyst is filled in a fixed bed reactor with the inner diameter of 8 mm, and the catalyst is pre-activated under the condition that N is₂The flow rate is 30ml/min, the temperature is increased to 450 ℃ at the speed of 2 ℃/min, the temperature is kept at 450 ℃ for 1 hour, then the temperature is reduced to the required reaction temperature of 330 ℃ under the nitrogen atmosphere, the reaction pressure is 0.1MPa, and the total mass space velocity of the raw material acetic acid is 0.1h^-1，N₂The flow rate was 20ml/min, and the volume percentage of acetic acid was 3.36%, under which the reaction results are shown in Table 3.

Examples 21 to 24

The other conditions were the same as in example 20 except that the reaction pressures were 0.3MPa, 0.5MPa, 0.7MPa and 0.8MPa, respectively. The reaction results are shown in Table 3.

TABLE 3 results of decarbonylation reactions at different reaction pressures

2.5 results of different atmospheric environments

Example 25

1g of No. 10 molecular sieve catalyst is filled in a fixed bed reactor with the inner diameter of 8 mm, and the catalyst is pre-activated under the condition that N is₂The flow rate is 30ml/min, the temperature is increased to 400 ℃ at the speed of 1 ℃/min, the temperature is kept at 400 ℃ for 2 hours, then the temperature is reduced to the required reaction temperature of 330 ℃ under the nitrogen atmosphere, the reaction pressure is 0.1MPa, and the total mass space velocity of the raw material acetic acid is 0.1h^-1，N₂The flow rate was 20ml/min, and the volume percentage of acetic acid was 3.36%, under which the reaction results are shown in Table 4.

Examples 26 to 29

The other conditions were the same as in example 25 except that the reaction atmosphere was hydrogen, helium, argon and carbon dioxide, respectively. The reaction results are shown in Table 4.

TABLE 4 decarbonylation results in different atmosphere environments

2.6 different feedstock mass airspeeds

Example 30

1g of No. 10 molecular sieve catalyst is filled in a fixed bed reactor with the inner diameter of 8 mm, and the catalyst is pre-activated under the condition that N is₂The flow rate is 30ml/min, the temperature is increased to 400 ℃ at the speed of 1 ℃/min, the temperature is kept at 400 ℃ for 2 hours, and then the temperature is reduced to the required reaction temperature of 330 ℃ under the nitrogen atmosphere, the reaction pressure is 0.1MPa, and N is₂The flow rate is 20ml/min, and the mass space velocity of the raw material acetic acid is controlled to be 0.1h by adjusting the flow of the constant flow pump^-1The volume percentage content of acetic acid under the condition is 3.36 percent. The reaction results under these conditions are shown in Table 5.

Examples 31 to 34

The other conditions were the same as in example 30 except that the mass space velocities of acetic acid were each set to 0.01h by adjusting the flow rate of the constant-flow pump^-1、1h^-1、2h^-1And 5h^-1. The reaction results are shown in Table 5.

TABLE 5 results of decarbonylation reactions at different acetic acid mass space velocities

2.7 results of different volume percentages of raw materials

Example 35

1g of No. 10 molecular sieve catalyst is filled in a fixed bed reactor with the inner diameter of 8 mm, and the catalyst is pre-activated under the condition that N is₂The flow rate is 30ml/min, the temperature is increased to 400 ℃ at the speed of 1 ℃/min, the temperature is kept at 400 ℃ for 2 hours, and then the temperature is reduced to the required reaction temperature of 330 ℃ under the nitrogen atmosphere, the reaction pressure is 0.1MPa, and N is₂The flow rate is 20ml/min, and the partial pressure of the raw materials is 1% of the reaction pressure (i.e. the volume percentage of acetic acid in the raw materials is 1% due to the utilization of N) by adjusting the temperature of the raw material bubbling tube₂Fed by bubbling and with N₂Is a diluent gas, so N₂99% by volume). The mass space velocity of the acetic acid is 0.037h^-1. The reaction results are shown in Table 6.

Examples 36 to 39

The other conditions were the same as in example 35 except that the bubbling tube temperature was adjusted so that the partial pressures of the raw materials were 5%, 10%, 40% and 60%, respectively. The reaction results are shown in Table 6.

TABLE 6 results of decarbonylation reactions with different volume contents of the starting materials

2.8 decarbonylation results with different Binders and amounts

Example 40(MOR)

1g of 10# molecular sieve catalyst is filled in a fixed material with the inner diameter of 8 mmIn a bed reactor, the catalyst is preactivated under the condition of N₂The flow rate is 30ml/min, the temperature is increased to 400 ℃ at the speed of 1 ℃/min, the temperature is kept at 400 ℃ for 2 hours, and then the temperature is reduced to the required reaction temperature of 330 ℃ under the nitrogen atmosphere, the reaction pressure is 0.1MPa, and N is₂The flow rate is 20ml/min, and the mass space velocity of the raw material acetic acid is 0.1h^-1The volume percentage of acetic acid at this time was 3.36%, and the reaction results under these conditions are shown in Table 7.

Examples 41-45 (silicon MOR), 46-50 (aluminum MOR)

Exchanging 100 g of baked Na-MOR molecular sieve (produced from Nankai catalyst factory) with 5 atomic ratio of silicon and aluminum for three times by 0.8mol/L ammonium nitrate solution at 80 ℃ for 2 hours, washing with deionized water, and drying to obtain NH₄-MOR. The obtained NH₄MOR was treated with 1000ml of 0.1mol/L citric acid solution at 80 ℃ for 1 h. After the treatment, the mixture was washed 3 times with deionized water and dried. 9g, 8g, 7g, 5g and 2g of NH4-MOR catalyst treated by citric acid is taken, 1g, 2g, 3g, 5g and 8g of silicon dioxide binder are added into the catalyst, the mixture is uniformly mixed and extruded, crushed and screened into particles of 40-60 meshes to obtain formed catalysts with the content of the binder of 10%, 20%, 30%, 50% and 80%, and the formed catalysts are roasted at 500 ℃ for 4H to obtain corresponding H-MOR, which is marked as a No. 15-19 catalyst. Catalysts using alumina as a binder, designated as catalysts # 20-24, were prepared in the same manner, and 1g of each was used as a reaction catalyst. The reaction conditions were the same as in example 40, and the reaction results are shown in Table 7.

TABLE 7 decarbonylation results for different catalyst binders and contents

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (9)

1. A method for preparing methyl acetate, characterized in that the method at least comprises the following steps: raw materials containing acetic acid are in contact reaction with a catalyst in a reactor to obtain methyl acetate;

the catalyst contains a base or acid modified molecular sieve;

the acetic acid is in a gaseous state during the reaction.

2. The method according to claim 1, wherein the reaction conditions are as follows: the reaction temperature is 300-400 ℃; the reaction pressure is 0.1-0.8 MPa; the mass airspeed of acetic acid in the raw materials is 0.01-5.0 h^-1。

3. The preparation method according to claim 1, wherein the volume percentage of acetic acid in the raw material is 0.1-100%.

4. The process of claim 1, wherein the feed gas further comprises a diluent gas;

the diluent gas is selected from at least one of hydrogen, nitrogen, helium, argon, and carbon dioxide.

5. The method according to claim 4, wherein the diluent gas is contained in the raw material in an amount of 0.01 to 99.9% by volume.

6. The method of claim 1, wherein the molecular sieve is selected from at least one of MOR molecular sieves;

preferably, the alkali or acid modified molecular sieve has a silicon-aluminum atomic ratio of 5-50.

7. The method according to claim 1, wherein the alkali is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide;

the acid is selected from any one of nitric acid, ammonium fluoride, oxalic acid and citric acid.

8. The method of claim 1, wherein the base-or acid-modified molecular sieve comprises a binder; the binder is at least one of alumina and silica.

9. The method of claim 1, wherein the reactor is a fixed bed reactor.