CN104059948B - A kind of method utilizing hydratase of acrylonitrile synthesis of acrylamide - Google Patents

Abstract

A method for synthesizing acrylamide by using acrylonitrile hydratase, comprising the following steps: providing a container containing free cell liquid; providing a membrane reactor, the membrane reactor comprising a microporous membrane, the microporous The membrane divides the membrane reactor into a first chamber and a second chamber; the free cell liquid is continuously added to the first chamber of the membrane reactor through a first delivery pipeline, and the free cell liquid is in the first chamber The chamber flows along the surface of the microporous membrane; acrylonitrile is provided, and the acrylonitrile is continuously added to the second chamber of the membrane reactor through a second delivery pipeline, and acrylonitrile enters the first chamber through the microporous membrane and is added to the flowing A mixed solution is formed after mixing in the free cell liquid; the mixed solution flows out from the second chamber into a reaction pipeline; and, the mixed solution in the reaction pipeline is circulated back to the container, and the solution in the container is recirculated into the membrane The first chamber of the reactor reacts with acrylonitrile circulating through the microporous membrane.

Description

A kind of method utilizing acrylonitrile hydratase to synthesize acrylamide

technical field

The invention relates to a method for synthesizing acrylamide by using acrylonitrile hydratase.

Background technique

As an important chemical raw material, acrylamide is mainly used for the preparation of polyacrylamide. As an excellent flocculant, polyacrylamide can be widely used in petroleum industry, mining industry, coal washing industry, metallurgical industry, water treatment, sugar industry, building materials industry and many other fields. Especially since the use of polyacrylamide in my country is still in the initial stage in the field of papermaking water treatment, with the enhancement of environmental protection awareness and emphasis on water treatment, the market demand for polyacrylamide in my country will further expand.

The traditional preparation methods of acrylamide generally include sulfuric acid hydrolysis and copper-catalyzed hydration. Among them, the sulfuric acid hydrolysis method uses acrylonitrile to react with 98% concentrated sulfuric acid, and ammonium sulfate will be produced during the reaction process. At the same time, the whole process is complicated, the consumption of sulfuric acid is large, the equipment is seriously corroded and polluted, and the cost is high, so it has gradually been adopted. disuse. The copper catalytic hydration method includes fixed bed catalytic hydration method and suspended bed catalytic hydration method. Generally, Cu-Ni and Cu-Cr catalysts are used, and its process is relatively simple compared with the sulfuric acid hydration method, but it also has the disadvantages of low conversion rate per pass and long reaction time. The emerging microbial method has a simple preparation process and a relatively green process. At the same time, due to the fast reaction speed of the enzyme-catalyzed reaction, the production efficiency can be greatly improved. Therefore, it has broad application prospects. At present, the main problems faced by the microbial method include the enzyme inactivation problem caused by mass transfer and the heat transfer problem of the hydration reaction.

Contents of the invention

Therefore, in order to overcome the above disadvantages, the present invention provides a new method for synthesizing acrylamide using acrylonitrile hydratase.

A method for synthesizing acrylamide by using acrylonitrile hydratase, comprising the following steps: providing a container containing free cell liquid, the temperature of which is less than 20 degrees Celsius; providing a membrane reactor, the membrane reactor comprising A microporous membrane, which divides the membrane reactor into a first space and a second space; the free cell liquid is continuously added to the first space of the membrane reactor through a first delivery pipeline, and the free cells The liquid flows along the surface of the microporous membrane in the first space; acrylonitrile is provided, and the acrylonitrile is continuously added to the second space of the membrane reactor through a second delivery pipeline, and the acrylonitrile enters the first space through the microporous membrane to add After being mixed into the flowing free cell liquid, a mixed solution is formed; the mixed solution flows out from the second space and enters a reaction pipeline, the temperature in the reaction pipeline is less than 20 degrees Celsius, and the length of the reaction pipeline is greater than 0.5 meters; and, the reaction pipeline The mixed solution in the reactor circulates back to the container, and the solution in the container recirculates into the first space of the membrane reactor to react with the acrylonitrile circulating through the microporous membrane.

Compared with the prior art, the present invention utilizes a membrane reactor, which can enable the two phases to be mixed rapidly and evenly under large phases by enhancing mass transfer, avoiding the problem of excessive local concentration of acrylonitrile; since acrylonitrile passes through micro After the porous membrane, it is dispersed into acrylonitrile droplets. Since the dispersed acrylonitrile droplets are small, the specific surface area of the reaction is greatly increased, thereby increasing the apparent reaction rate of the reaction. At the same time, the faster reaction can reduce the The contact time between acrylamide and cells can reduce the inhibitory effect of the product on the enzyme activity to a certain extent; due to the excellent heat transfer performance of the membrane reactor, the heat of reaction can be removed quickly, thus avoiding the damage caused by excessive reaction temperature. Enzyme inactivation problem.

Description of drawings

Fig. 1 is a flow chart of the method for preparing acrylamide using a membrane reactor provided by the present invention.

Fig. 2 is a schematic diagram of a method and device for preparing acrylamide provided by the present invention using a membrane reactor.

Fig. 3 is an enlarged schematic diagram of the membrane reactor provided by the present invention.

Description of main component symbols

container 100

Blender 102

Membrane reactor 200

Microporous membrane 202

First Space 204

Second space 206

First delivery pipeline 300

Second delivery pipeline 400

Reaction pipeline 500

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

detailed description

Please refer to Fig. 1 to Fig. 3, the present invention provides a kind of method utilizing acrylonitrile hydratase to synthesize acrylamide, which comprises the following steps:

S1: Provide a container 100, the container 100 contains free cell fluid, and the temperature of the container 100 is less than 5 degrees Celsius;

S2: provide a membrane reactor 200, the membrane reactor 200 includes a microporous membrane 202, the microporous membrane 202 divides the membrane reactor 200 into a first space 204 and a second space 206;

S3: The free cell liquid is continuously added to the first space 204 of the membrane reactor 200 through a first delivery pipeline 300, and the free cell liquid flows along the surface of the microporous membrane 202 in the first space 204;

S4: provide acrylonitrile, which is continuously added to the second space 206 of the membrane reactor 200 through a second delivery pipeline 400, and acrylonitrile passes through the microporous membrane 202 and enters the first space 204 to be added to the flowing free cell liquid form a mixture after mixing;

S5: The mixed liquid flows out from the first space 204 into a reaction pipeline 500, the temperature in the reaction pipeline 500 is less than 5 degrees Celsius, and the length of the reaction pipeline 500 is greater than 0.5 meters; and

S6: The mixed liquid in the reaction pipeline 500 circulates back to the container 100 , and the solution in the container 100 recirculates into the first space 204 of the membrane reactor 200 to react with the acrylonitrile circulating through the microporous membrane 202 .

In step S1, the container 100 can be a wide-mouthed container, such as a beaker, or a container 100 with at least three openings, such as a three-necked bottle. In the present embodiment, select three-neck bottle for use. The container 100 is placed in a water bath environment or a heat preservation device, and its temperature is kept below 20°C. The free cell liquid contains acrylonitrile hydratase, the activity of which is 1500-2500U/ml. In this embodiment, the temperature of the container 100 is maintained at 5° C., and the enzyme activity in the free cell fluid is 2000 U/ml. The container 100 further includes a stirrer 102, and the stirrer 102 continuously stirs the solution in the container 100.

In step S2, the membrane reactor is a microreactor. The micropore diameter of the microporous membrane 202 is 2-10 microns, and in this embodiment, the micropore diameter of the microporous membrane 202 is 5 microns. The micropores may be polymer materials, metal materials coated with a protective layer or other composite materials. The microporous membrane 202 has two opposing surfaces, a first surface and a second surface. The microporous membrane has a plurality of micropores passing through the microporous membrane 202 along the thickness direction. The first space 204 and the second space 206 are located on both sides of the microporous membrane 202 respectively, and their sizes can be selected according to actual requirements. The first surface of the microporous membrane 202 is located in the first space 204 , and the second surface is located in the second space 206 .

In step S3 , after the free cell liquid is added into the first space 204 , it flows in the first space 204 parallel to the first surface of the microporous membrane 202 . The flow rate of the free cell liquid is 2-4 ml/min. In this embodiment, the free cell fluid is in contact with the microporous membrane 202 and flows along a direction parallel to the first surface of the microporous membrane 202 .

In step S4, the acrylonitrile is pure acrylonitrile and is an oil phase. Acrylonitrile is continuously fed into the second space 206 through the second delivery pipe 400 . The flow rate of acrylonitrile is determined not to overflow the membrane reactor 200 . Acrylonitrile is added vertically through the second surface of the microporous membrane 202 into the flowing free cell solution. The vertical addition means that the direction of adding acrylonitrile is perpendicular to the direction of flow of free cell fluid. During this process, after passing through the microporous membrane 202, the acrylonitrile is divided into a plurality of tiny droplets. The free cells are fully dispersed in the liquid, and the reaction materials are fully mixed, so that the acrylonitrile starts to undergo hydration reaction to generate acrylamide. In this step, the membrane reactor 200 is used to avoid the problem of excessive local concentration of acrylonitrile. At the same time, because the dispersed acrylonitrile droplets are small, the specific surface area of the reaction is greatly increased, thereby improving the apparent surface area of the reaction. reaction speed. At the same time, the faster reaction can reduce the contact time between acrylamide and cells, so the inhibitory effect of the product on the enzyme activity can be reduced to a certain extent.

In step S5 , after the mixed liquid in step S4 flows into the reaction pipeline 500 , the reaction continues in the reaction pipeline 500 to form acrylamide. The length of the reaction pipeline 500 should be greater than 0.5 meters, so that the acrylonitrile and the free cell liquid have sufficient reaction time. The reaction pipeline 500 can be a convoluted pipeline. The reaction tube 500 is placed in a water bath environment so that its temperature is maintained at less than 20 °C.

In step S6, the mixed liquid is returned to the container 100 from the reaction pipeline 500, and after mixing with the solution in the container 100, the mixed liquid is transported back to the membrane reactor from the first transport pipeline 300, and is again mixed with the solution from the second transport pipeline 300. The free cell liquid passing through the microporous membrane 202 in the space 206 reacts.

According to the steps from S1 to S6, the reaction is circulated for a period of time, and acrylamide with higher concentration can be obtained after stopping. During the response process, about 2 mL of the mixture in the container 100 can be taken out at regular intervals, and the concentration of acrylamide in the product can be measured by gas chromatography. When the concentration of acrylamide reaches the desired concentration, the circulation reaction can be stopped.

In the preparation method of acrylamide provided by the present invention, acrylonitrile undergoes a hydration reaction under the catalysis of acrylonitrile hydratase in free cell fluid:

In the above reaction process, because acrylonitrile and the acrylamide produced will inhibit the enzyme activity of acrylonitrile hydratase, experiments have shown that acrylonitrile will inhibit the enzyme activity when the concentration reaches 0.4mol/L. The cell culture medium must be added slowly. Therefore, in the traditional preparation method of acrylamide, the whole reaction takes a long time, and in order to ensure sufficient mixing, strong stirring is often used to increase energy consumption to a large extent; on the other hand, since acrylamide reaches 250g/ L also has a more obvious inhibitory effect on the enzyme activity, so the traditional industrial stirred tank reactor can only obtain acrylamide products with a lower concentration in a longer reaction time. If you want to increase the product concentration, you must Adding a concentration step makes the whole process more complicated; at the same time, because the hydration reaction of acrylonitrile is a fast reaction accompanied by a large heat release, it is often cooled by liquid ammonia and frozen brine, thus further increasing the energy consumption and production of the reaction. cost.

In the present invention, the membrane reactor is used to prepare acrylamide, and the acrylonitrile is divided into a plurality of tiny droplets through the microporous membrane. , so that the droplets of acrylonitrile are fully dispersed in the free cell fluid, and the reaction materials are fully mixed, which avoids the problem of excessive local concentration of acrylonitrile; at the same time, because the dispersed acrylonitrile droplets are small, greatly increased The specific surface area of the reaction improves the apparent reaction rate of the reaction; at the same time, the faster reaction can reduce the contact time between acrylamide and cells, so the inhibitory effect of acrylamide on enzyme activity can be reduced to a certain extent; another On the one hand, due to the excellent heat transfer performance of the membrane reactor, the heat of reaction can be removed quickly, thus avoiding the problem of enzyme inactivation caused by too high reaction temperature.

The preparation process of the acrylamide of the present invention is simple and easy to operate, and the energy consumption is low. By adjusting the process conditions such as two-phase flow, two-phase phase ratio and reaction temperature, 60% of the acrylamide product can be achieved within 30 minutes under optimal conditions, and the concentration of acrylonitrile and acrylic acid in the product can be ignored. The whole preparation process is green, safe, efficient and highly controllable.

The present invention is further illustrated below by specific examples, but it is not intended to limit the scope of the present invention.

Example 1

The dispersed phase used is the oil phase, that is, pure acrylonitrile. The initial continuous phase is free cell fluid of Rhodococcus type TH3. Take 80mL of free cell solution with an enzyme activity of 2000U, put it into a three-neck flask and stir. The three-neck flask was placed in an ice-water bath to ensure that the temperature of the entire reaction system was not higher than 5°C. A membrane dispersion reactor is used to mix and react acrylonitrile and free cell liquid, the continuous phase is continuously circulated and the dispersed phase is sheared to form monodisperse acrylonitrile droplets, and the catalytic reaction is carried out. After the mixed acrylonitrile and free cell liquid are mixed, the reaction continues through a 1-meter-long coil, and the temperature in the coil is guaranteed not to be higher than 5°C. The reacted mixed solution flows into a three-necked flask to continue to catalyze the acrylonitrile and circulate continuously. 2 mL of the mixture in the three-neck flask was taken out at regular intervals, and the concentration of acrylamide in the product was determined by gas chromatography. Wherein, the ratio of the continuous phase to the dispersed phase is 30, and the flow rate of the dispersed phase is between 1-5min/mL.

Example 2

The dispersed phase used is the oil phase, that is, pure acrylonitrile. The initial continuous phase is free cell fluid of Rhodococcus type TH3. Take 80mL of free cell solution with an enzyme activity of 2000U, put it into a three-neck flask and stir. The three-neck flask was placed in an ice-water bath to ensure that the temperature of the entire reaction system was not higher than 5°C. A membrane dispersion reactor is used to mix and react acrylonitrile and free cell liquid, the continuous phase is continuously circulated and the dispersed phase is sheared to form monodisperse acrylonitrile droplets, and the catalytic reaction is carried out. After the mixed acrylonitrile and free cell liquid are mixed, the reaction continues through a 1-meter-long coil, and the temperature in the coil is guaranteed not to be higher than 5°C. The reacted mixed solution flows into a three-necked flask to continue to catalyze the acrylonitrile and circulate continuously. 2 mL of the mixture in the three-neck flask was taken out at regular intervals, and the concentration of acrylamide in the product was determined by gas chromatography. The continuous phase flow rate is 70-50mL/min, and the dispersed phase flow rate is 10-2mL/min. The above experiment was repeated and the reaction temperature was controlled at 10-20°C.

Example 3

The dispersed phase used is the oil phase, that is, pure acrylonitrile. The initial continuous phase is free cell fluid of Rhodococcus type TH3. Take 80mL of free cell solution with an enzyme activity of 2000U, put it into a three-neck flask and stir. The three-neck flask was placed in an ice-water bath to ensure that the temperature of the entire reaction system was not higher than 5°C. A membrane dispersion reactor is used to mix and react acrylonitrile and free cell liquid, the continuous phase is continuously circulated and the dispersed phase is sheared to form monodisperse acrylonitrile droplets, and the catalytic reaction is carried out. After the mixed acrylonitrile and free cell liquid are mixed, the reaction continues through a 1-meter-long coil, and the temperature in the coil is guaranteed not to be higher than 5°C. The reacted mixed solution flows into a three-necked flask to continue to catalyze the acrylonitrile and circulate continuously. 2 mL of the mixture in the three-necked flask was taken out at regular intervals, and the concentration of acrylamide in the product was determined by gas chromatography. Wherein the ratio of the continuous phase to the dispersed phase is between 40-10. The flow rate of the continuous phase was fixed at 80mL/min.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included within the scope of protection claimed by the present invention.

Claims (10)

1. the method utilizing hydratase of acrylonitrile synthesis of acrylamide, it comprises the following steps:

S1: provide a container, fills free cell liquid in this container, containing acrylonitrile water in this free cell liquid Synthase, the temperature of this container is less than 20 degrees Celsius；

S2: provide a membrane reactor, this membrane reactor includes a microporous membrane, and membrane reactor is divided into by this microporous membrane First space and second space；

S3: described free cell liquid is continuously added to membrane reactor described in S2 by one first conveyance conduit First space, and make free cell liquid Surface runoff along microporous membrane in the first space；

S4: providing acrylonitrile, this acrylonitrile is continuously added to second to membrane reactor by one second conveyance conduit Space, acrylonitrile enters the first space addition through microporous membrane and forms one to mixing in the free cell liquid of flowing Mixed liquor；

S5: described mixed liquor exits into a reacting pipe from the first space, the temperature in this reacting pipe is less than 20 degrees Celsius, the length of reacting pipe is more than 0.5 meter；

S6: described container is flowed back in the mixed liquor circulation in reacting pipe, and the recycling solution in this container flows into film First space of reactor, with the acrylonitrile circular response through microporous membrane.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most as claimed in claim 1, it is characterised in that Containing hydratase of acrylonitrile in described free cell liquid, its activity is 1500～2500U/ml.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most as claimed in claim 1, it is characterised in that The micropore size of described microporous membrane is 2～10 microns.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most as claimed in claim 1, it is characterised in that Described free cell liquid adds to the first space, along the Surface runoff being parallel to microporous membrane in the first space.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most as claimed in claim 4, it is characterised in that Described acrylonitrile directly and vertically adds to free cell liquid after microporous membrane.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most as claimed in claim 1, it is characterised in that Described acrylonitrile is pure acrylonitrile.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most according to claim 1, its feature exists In, described container and reacting pipe are placed in water bath.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most according to claim 1, its feature exists In, described container farther includes an agitator, and the solution in container is carried out continuous stirring.

The method utilizing hydratase of acrylonitrile synthesis of acrylamide the most as claimed in claim 1, it is characterised in that During circular response, at set intervals, take out the spiece in container, and by gas phase color Spectrum measures the concentration of acrylamide in this mixture.

10. the method utilizing hydratase of acrylonitrile synthesis of acrylamide, it comprises the following steps:

S1: provide a membrane reactor, this membrane reactor includes a microporous membrane, and this microporous membrane has relative first Surface and second surface；

S2: provide a free cell liquid in a container, containing hydratase of acrylonitrile in this free cell liquid, be somebody's turn to do Free cell liquid flows along the first surface of microporous membrane；

S3: provide acrylonitrile, this acrylonitrile adds the trip to flowing from the second surface of microporous membrane through microporous membrane In Cell sap, form mixed liquor；And

S4: the liquid in described mixed liquor reacts generation acrylamide, and mixed liquor flows into free cell liquid Container mixes with free cell liquid, inputs membrane reactor the most again and flows along the first surface of microporous membrane, and passes The acrylonitrile generation circular response of microporous membrane.