System and method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using jet loop reactor
阅读说明：本技术 利用喷射环流反应器连续化生产优质高选择性苯甲醛和苯甲酸的系统及方法 (System and method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using jet loop reactor ) 是由 孙波 舒振操 程娟 代飞 聂少春 黄正望 毛利民 于 2020-06-02 设计创作，主要内容包括：本发明公开了一种利用喷射环流反应器连续化生产优质高选择性苯甲醛和苯甲酸的系统及方法。该系统包括喷射环流反应器、脱甲苯塔、间壁塔和苯甲醛精馏塔；基于该系统,本发明通过以甲苯为原料,氧气为氧化剂,有机盐为催化剂,在喷射环流反应器中进行甲苯氧化反应,并将反应后的氧化液经脱甲苯塔、间壁塔和苯甲醛精馏塔进行产品提纯,从而实现连续化生产优质高选择性苯甲醛和苯甲酸。通过上述方式,本发明能够有效提高苯甲醛的选择性,并生产出纯度较高的优质苯甲酸和苯甲醛；且生产系统结构简单、设备投资低,生产方法操作简单、易于控制、反应时间短、原料利用率高,整体反应过程也安全稳定、绿色环保。(The invention discloses a system and a method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor. The system comprises a jet loop reactor, a benzene removing tower, a dividing wall tower and a benzaldehyde rectifying tower; based on the system, the invention takes toluene as raw material, oxygen as oxidant and organic salt as catalyst, carries out toluene oxidation reaction in the jet loop reactor, and carries out product purification on the oxidation liquid after reaction through a toluene removing tower, a dividing wall tower and a benzaldehyde rectifying tower, thereby realizing continuous production of high-quality and high-selectivity benzaldehyde and benzoic acid. Through the mode, the selectivity of benzaldehyde can be effectively improved, and high-quality benzoic acid and benzaldehyde with high purity are produced; and the production system has simple structure, low equipment investment, simple operation of the production method, easy control, short reaction time, high utilization rate of raw materials, safe and stable whole reaction process and environmental protection.)
1. A system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor is characterized in that: comprises a jet loop reactor, a toluene removing tower, a dividing wall tower and a benzaldehyde rectifying tower; the jet loop reactor comprises a feed inlet, a high-pressure reaction kettle, a loop circulating pump, a tubular heat exchanger, a Venturi ejector and a reaction liquid discharge port; the reaction liquid discharge port is communicated with the middle feed port of the toluene removing tower, the tower bottom discharge port of the toluene removing tower is communicated with the middle feed port of the dividing wall tower, and the tower top discharge port of the dividing wall tower is communicated with the middle feed port of the benzaldehyde rectifying tower.
2. The system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 1, wherein the system comprises: the feed inlets of the jet loop reactor comprise a nitrogen feed inlet, an oxygen feed inlet, a toluene feed inlet, a catalyst feed inlet and a recovered toluene feed inlet; a discharge hole at the top of the tower of the toluene removing tower is provided with a layering tank, a water phase outlet of the layering tank is communicated with a wastewater storage tank, and an oil phase outlet of the layering tank is respectively communicated with a reflux channel at the top of the tower and a toluene recovery channel; the toluene recovery channel is communicated with the toluene recovery feed inlet.
3. The system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 1, wherein the system comprises: the dividing wall tower adopts a packed tower, and the packing comprises a tower top rectifying section, a middle rectifying section and a tower kettle stripping section; the tower top rectifying section is communicated with a tower top discharge hole of the dividing wall tower and is used for outputting mixed liquid containing benzaldehyde; the tower kettle stripping section is communicated with a tower bottom discharge hole of the dividing wall tower and is used for outputting the rectifying kettle residues; the intermediate rectifying section is vertically provided with a partition plate, one side of the partition plate is an inlet side, the other side of the partition plate is an outlet side, and the outlet side is communicated with a lateral line discharge port of the dividing wall tower and used for outputting a finished benzoic acid product.
4. The system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 1, wherein the system comprises: and an emergency vent valve is arranged at the top end of the high-pressure reaction kettle and used for ensuring the safe reaction in the high-pressure reaction kettle.
5. A method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, which is characterized in that the method is produced by using the system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in any one of claims 1 to 4, and comprises the following steps:
s1, oxidation reaction: introducing inert gas into the top end of the jet loop reactor, and continuously adding the raw materials of toluene and the organic salt catalyst into the jet loop reactor; starting a loop circulating pump, controlling the jet flow speed, sucking oxygen into a Venturi ejector by using negative pressure formed by the Venturi ejector, fully mixing and dispersing the oxygen and reaction materials, and spraying the oxygen into a high-pressure reaction kettle for oxidation reaction to obtain reaction liquid;
s2, benzene removing treatment: inputting the reaction liquid obtained in the step S1 into a benzene removing tower, controlling the pressure of the top of the benzene removing tower to be-65 to-75 kPa, so that toluene and water are output from the top of the tower, and the liquid of the benzene removing kettle is output from the bottom of the tower; after the toluene and the water output from the tower top are layered, the lower layer of water phase enters a wastewater storage tank, one part of the upper layer of oil phase reflows to the tower top through a pump, and the other part of the upper layer of oil phase is pumped to the high-pressure reaction kettle;
s3, dividing wall column separation treatment: inputting the demethylation kettle liquid obtained in the step S2 into a dividing wall tower, controlling the pressure of the top of the dividing wall tower to be-88 to-95 kPa, so that a low-boiling mixture is output from the top of the dividing wall tower in a steam form, rectifying a high-boiling mixture to obtain a benzoic acid finished product with the purity of more than 99.5 percent, and outputting the residue of the rectifying kettle from the bottom of the tower; condensing steam output from the tower top to a reflux tank, refluxing one part of the steam to the tower top by a pump, and extracting the other part of the steam serving as mixed liquid containing benzaldehyde, wherein the content of the benzaldehyde in the mixed liquid is more than 60%;
s4, benzaldehyde rectification treatment: inputting the mixed solution containing benzaldehyde obtained in the step S2 into a benzaldehyde rectifying tower, controlling the pressure of the top of the benzaldehyde rectifying tower to be-88 to-95 kPa, outputting the obtained benzaldehyde from the top of the tower, and outputting the rectifying kettle residue from the bottom of the tower; one part of the benzaldehyde output from the tower top is refluxed to the tower top through a pump, the other part of the benzaldehyde is taken as a benzaldehyde finished product to be extracted, and the purity of the benzaldehyde finished product is 99.9%.
6. The method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 5, wherein the jet loop reactor comprises: in step S1, the jet flow speed is 50-70 m/S; the molar ratio of the toluene to the oxygen is (0.7-1.2) to 1; the pressure of the oxidation reaction is 0.3-0.8 MPa, the reaction temperature is 130-180 ℃, and the average residence time of the liquid phase substance in the jet loop reactor is 0.5-1.5 h.
7. The method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 5, wherein the jet loop reactor comprises: in step S2, the temperature of the demethanizer is 180-220 ℃, the top temperature is 65-110 ℃, and the reflux ratio is (0.5-1.5): 1.
8. The method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 5, wherein the jet loop reactor comprises: in step S3, the kettle temperature of the dividing wall tower is 180-230 ℃, the top temperature is 110-160 ℃, the internal reflux distribution ratio is 1 (1-8), the light component reflux ratio is 10-40: 1, and the finished product reflux ratio is 1 (2-6).
9. The method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 5, wherein the jet loop reactor comprises: in step S4, the temperature of the benzaldehyde rectification tower is 110-160 ℃, the top temperature is 80-130 ℃, and the reflux ratio is (5-15): 1.
10. The method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor as claimed in claim 5, wherein the jet loop reactor comprises: in step S1, the organic salt catalyst is one or more of organic salts of cobalt ions, manganese ions, and nickel ions.
Technical Field
The invention relates to the technical field of organic synthesis processes, in particular to a system and a method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor.
Background
Benzoic acid and benzaldehyde are important fine chemical products. Wherein, the benzoic acid is one of the important raw materials in the organic synthesis industry, can be used as a food preservative, an antirust agent of steel equipment, a mordant for dyeing and printing and a modifier of carboxylic acid resin, can also be used as an intermediate of pharmacy and dye, and has wide application range; benzaldehyde, which is the simplest important aromatic aldehyde, has high industrial added value and also has important value in the fields of agriculture, medicine, food, dye and the like.
At present, the industry mainly adopts a toluene liquid-phase air oxidation method to produce benzoic acid and benzaldehyde. The toluene liquid phase air oxidation method is that toluene and air are subjected to catalytic oxidation reaction in the presence of a catalyst to generate a main product benzoic acid and a certain amount of benzaldehyde as a byproduct. However, the selectivity of the benzaldehyde by-product obtained by the current method is usually low, the yield is small, the actual demand cannot be met, and the separation value is low. In addition, the toluene chlorination-hydrolysis method adopted in the prior industrial production of benzaldehyde has the problems of complex process, serious equipment corrosion, generation of a large amount of chlorine-containing wastewater, environmental pollution and the like, and the prepared benzaldehyde product is difficult to separate with a small amount of chlorine-containing impurities and can not meet the requirements of the fields of medicines, spices, foods and the like on the quality of raw materials. Therefore, there is still a need for producing benzaldehyde by toluene oxidation, and how to continuously produce benzoic acid while increasing the selectivity of benzaldehyde and obtaining high-quality and high-selectivity benzaldehyde and benzoic acid is the focus of current research.
At present, reactors used for industrially producing benzoic acid and benzaldehyde include a tank reactor and a bubble reactor. Wherein, the bubbling reactor is difficult to effectively control the process of the toluene oxidation reaction, which results in lower selectivity and yield of the intermediate product benzaldehyde; meanwhile, as the toluene liquid-phase oxidation reaction is a strong exothermic reaction, the reaction heat needs to be removed in time in the reaction process, but the bubbling reactor is additionally provided with a heat exchange device, so that the problems of complex structure, low heat removal efficiency and the like are caused; in addition, air or high-concentration oxygen is introduced into the bubbling reactor in a bubbling mode, so that the mass transfer efficiency is low, the toluene oxidation reaction time is prolonged, the selectivity of the intermediate product benzaldehyde is low, and a large amount of tail gas containing toluene or products is generated to pollute the environment.
In order to solve the problems of the bubbling reactor, the patent with the publication number of CN104907008B provides a reaction device and a method for preparing benzoic acid and benzaldehyde by direct oxidation of toluene, and the patent adopts a tubular reactor to improve the controllability of the reaction process, thereby improving the selectivity and the yield of the intermediate product benzaldehyde. However, the device provided by the patent needs to use a large number of tubular reaction sleeves, the device is complex, unreacted oxygen is easy to accumulate at the upper part of the reactor, the explosion limit is reached, potential safety hazards are formed, and the industry is not easy to realize; in addition, although the device can effectively improve the selectivity of benzaldehyde, the benzaldehyde cannot be effectively purified, the purity of the obtained product is not high, the toluene conversion rate in the production process is low, and the production efficiency is not high. Therefore, there is still a need for improvement of the apparatus and method for producing benzoic acid, which can produce high-quality and high-selectivity benzaldehyde and benzoic acid while ensuring production safety and production efficiency.
In various reactors, the jet loop reactor uses a high-speed mobile phase to entrain other phases, obtains a high mixing effect with relatively low energy consumption, and injects the mixed phase into a reaction kettle to form an overall good loop to promote the reaction to be continuously carried out, so that the jet loop reactor is very suitable for heterogeneous reaction with limited mass transfer, but the specific application mode of the jet loop reactor in the production process of benzoic acid and benzaldehyde is still to be researched.
In view of the above, there is a need for a system and a method for continuously producing benzoic acid and benzaldehyde by using a jet loop reactor, so as to safely and efficiently produce high-quality and high-selectivity benzaldehyde and benzoic acid.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, an object of the present invention is to provide a system and a method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, wherein toluene is used as a raw material, oxygen is used as an oxidant, and an organic salt is used as a catalyst, so that the toluene is subjected to a toluene oxidation reaction in the jet loop reactor, and the oxidation liquid after the reaction is subjected to product purification by a toluene removal tower, a dividing wall tower and a benzaldehyde rectification tower, thereby continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid.
In order to achieve the aim, the invention provides a system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, which comprises the jet loop reactor, a benzene removing tower, a dividing wall tower and a benzaldehyde rectifying tower, wherein the jet loop reactor is connected with the benzene removing tower; the jet loop reactor comprises a feed inlet, a high-pressure reaction kettle, a loop circulating pump, a tubular heat exchanger, a Venturi ejector and a reaction liquid discharge port; the reaction liquid discharge port is communicated with the middle feed port of the toluene removing tower, the tower bottom discharge port of the toluene removing tower is communicated with the middle feed port of the dividing wall tower, and the tower top discharge port of the dividing wall tower is communicated with the middle feed port of the benzaldehyde rectifying tower.
Further, the feed inlets of the jet loop reactor comprise a nitrogen feed inlet, an oxygen feed inlet, a toluene feed inlet, a catalyst feed inlet and a recovered toluene feed inlet; a discharge hole at the top of the tower of the toluene removing tower is provided with a layering tank, a water phase outlet of the layering tank is communicated with a wastewater storage tank, and an oil phase outlet of the layering tank is respectively communicated with a reflux channel at the top of the tower and a toluene recovery channel; the toluene recovery channel is communicated with the toluene recovery feed inlet.
Furthermore, the dividing wall tower adopts a packed tower, and the packing comprises a tower top rectifying section, an intermediate rectifying section and a tower kettle stripping section; the tower top rectifying section is communicated with a tower top discharge hole of the dividing wall tower and is used for outputting mixed liquid containing benzaldehyde; the tower kettle stripping section is communicated with a tower bottom discharge hole of the dividing wall tower and is used for outputting the rectifying kettle residues; the intermediate rectifying section is vertically provided with a partition plate, one side of the partition plate is an inlet side, the other side of the partition plate is an outlet side, and the outlet side is communicated with a lateral line discharge port of the dividing wall tower and used for outputting a finished benzoic acid product.
Furthermore, an emergency vent valve is arranged at the top end of the high-pressure reaction kettle and used for guaranteeing the safe reaction in the high-pressure reaction kettle.
In order to achieve the above object, the present invention further provides a method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, the method using the system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, the method comprising the following steps:
s1, oxidation reaction: introducing inert gas into the top end of the jet loop reactor, and continuously adding the raw materials of toluene and the organic salt catalyst into the jet loop reactor; starting a loop circulating pump, controlling the jet flow speed, sucking oxygen into a Venturi ejector by using negative pressure formed by the Venturi ejector, fully mixing and dispersing the oxygen and reaction materials, and spraying the oxygen into a high-pressure reaction kettle for oxidation reaction to obtain reaction liquid;
s2, benzene removing treatment: inputting the reaction liquid obtained in the step S1 into a benzene removing tower, controlling the pressure of the top of the benzene removing tower to be-65 to-75 kPa, so that toluene and water are output from the top of the tower, and the liquid of the benzene removing kettle is output from the bottom of the tower; after the toluene and the water output from the tower top are layered, the lower layer of water phase enters a wastewater storage tank, one part of the upper layer of oil phase reflows to the tower top through a pump, and the other part of the upper layer of oil phase is pumped to the high-pressure reaction kettle;
s3, dividing wall column separation treatment: inputting the demethylation kettle liquid obtained in the step S2 into a dividing wall tower, controlling the pressure of the top of the dividing wall tower to be-88 to-95 kPa, so that a low-boiling mixture is output from the top of the dividing wall tower in a steam form, rectifying a high-boiling mixture to obtain a benzoic acid finished product with the purity of more than 99.5 percent, and outputting the residue of the rectifying kettle from the bottom of the tower; condensing steam output from the tower top to a reflux tank, refluxing one part of the steam to the tower top by a pump, and extracting the other part of the steam serving as mixed liquid containing benzaldehyde, wherein the content of the benzaldehyde in the mixed liquid is more than 60%;
s4, benzaldehyde rectification treatment: inputting the mixed solution containing benzaldehyde obtained in the step S2 into a benzaldehyde rectifying tower, controlling the pressure of the top of the benzaldehyde rectifying tower to be-88 to-95 kPa, outputting the obtained benzaldehyde from the top of the tower, and outputting the rectifying kettle residue from the bottom of the tower; one part of the benzaldehyde output from the tower top is refluxed to the tower top through a pump, the other part of the benzaldehyde is taken as a benzaldehyde finished product to be extracted, and the purity of the benzaldehyde finished product is 99.9%.
Further, in the step S1, the jet flow speed is 50-70 m/S; the molar ratio of the toluene to the oxygen is (0.7-1.2) to 1; the pressure of the oxidation reaction is 0.3-0.8 MPa, the reaction temperature is 130-180 ℃, and the average residence time of the liquid phase substance in the jet loop reactor is 0.5-1.5 h.
Further, in step S2, the temperature of the demethanizer is 180-220 ℃, the top temperature is 65-110 ℃, and the reflux ratio is (0.5-1.5): 1.
Further, in step S3, the temperature of the intermediate wall tower is 180-230 ℃, the top temperature is 110-160 ℃, the distribution ratio of internal reflux is 1 (1-8), the reflux ratio of the light components is (10-40): 1, and the reflux ratio of the finished product is 1 (2-6).
Further, in step S4, the temperature of the benzaldehyde rectification tower is 110-160 ℃, the top temperature is 80-130 ℃, and the reflux ratio is (5-15): 1.
Further, in step S1, the organic salt catalyst is one or more of organic salts of cobalt ions, manganese ions, and nickel ions.
Compared with the prior art, the invention has the beneficial effects that:
1. the system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor comprises the jet loop reactor, the toluene removing tower, the dividing wall tower and the benzaldehyde rectifying tower, can realize continuous production of the benzoic acid and the benzaldehyde, has a simple integral structure, is easy to control, has low equipment investment, and meets the requirement of industrial production. Based on the system, the invention also provides a method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor, wherein toluene is used as a raw material, oxygen is used as an oxidant, organic salt is used as a catalyst, toluene oxidation reaction is carried out in the jet loop reactor, and the oxidation liquid after the reaction is purified by a toluene removing tower, a dividing wall tower and a benzaldehyde rectifying tower, so that high-quality and high-selectivity benzaldehyde and benzoic acid are continuously produced; the method is simple to operate, easy to control, short in reaction time, high in raw material utilization rate, safe and stable in the whole reaction process, and environment-friendly.
2. The invention adopts the jet loop reactor to carry out toluene oxidation reaction, can ensure that gas-liquid contact is more sufficient, and the reaction speed is accelerated, the reaction retention time is short, thereby effectively improving the selectivity of benzaldehyde, and increasing the proportion of benzaldehyde in the product obtained after oxidation. The price of the benzaldehyde is higher than that of benzoic acid, so that the product price can be increased by increasing the proportion of the benzaldehyde in the oxidation product, and the product has higher commercial value; meanwhile, the invention overcomes the problems that the benzaldehyde is easy to oxidize and is not easy to exist in the system, improves the proportion of the benzaldehyde in the product and has higher technical value. In addition, the shearing action of the high-speed liquid in the jet loop reactor can break the gas into very small bubbles and generate larger gas-liquid contact specific surface area, thereby realizing higher mass transfer efficiency and achieving higher conversion rate; and the toluene oxidation reaction condition in the jet loop reactor is mild, the reaction process is controllable, and the side reaction is less. In addition, the jet circulation reactor provided by the invention is provided with an external tubular heat exchanger, so that the heat transfer efficiency is higher, the reaction heat can be removed in time, and the reaction is promoted to be carried out.
3. The invention adopts the dividing wall tower to realize the separation of the benzoic acid from other products in the system, and the dividing wall tower separates the tower sections on the feeding side and the extraction side by utilizing the partition plate, so that the high-purity benzoic acid product can be obtained. Compared with the traditional double-tower separation system for removing the light products, the invention can save one tower, one condenser and one reboiler by using the dividing wall tower, thereby simplifying the process flow, reducing the equipment investment, greatly reducing the energy consumption in the separation process and playing the roles of energy conservation and environmental protection.
4. The invention can make the utilization rate of the pure oxygen reach 100 percent by using the pure oxygen as the oxidant; meanwhile, nitrogen is introduced into the top of the jet loop reactor as protective gas, and the system pressure can be maintained by controlling the nitrogen partial pressure in the reaction process, so that the safety interlocking is realized; and the emergency air-defense valve is arranged, so that the emergency air-defense valve can be automatically opened when the pressure is ultrahigh, and the safe reaction is further ensured. And the whole reaction process has no tail gas emission, and is green, safe and environment-friendly.
5. The method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor can improve the reaction efficiency of toluene oxidation reaction, and enables the conversion per pass of toluene to be 40-50%; meanwhile, the method can also improve the selectivity of the product, so that the total selectivity of the benzoic acid and the benzaldehyde is over 95 percent, wherein the selectivity of the benzaldehyde is 10 to 15 percent, and the method can be adjusted according to actual production requirements. In addition, the method provided by the invention can be used for efficiently purifying the product to obtain high-quality benzoic acid and benzaldehyde, wherein the content of benzoic acid in the finished product of benzoic acid is more than 99.5%, and the content of benzaldehyde in the finished product of benzaldehyde is 99.9%, so that the requirement of practical application can be met.
Drawings
FIG. 1 is a schematic structural diagram of a system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, which is provided by the invention;
the parts in the drawings are numbered as follows: 1. a jet loop reactor; 101. a high-pressure reaction kettle; 102. a loop circulation pump; 103. a shell and tube heat exchanger; 104. a venturi ejector; 105. an emergency vent valve; 106. a nitrogen feed inlet; 107. an oxygen feed port; 108. a toluene feed inlet; 109. a catalyst feed port; 110. a feeding hole for recovering toluene; 111. a discharge hole of the reaction liquid; 112. a steam drum; 2. a demethanizer column; 201. the middle feed inlet of the toluene removing tower; 202. a discharge hole at the top of the demethanizer; 203. a discharge hole at the bottom of the tower of the toluene removing tower; 204. a top reflux channel; 205. a toluene recovery channel; 206. a layering tank; 207. a wastewater storage tank; 3. a divided wall column; 301. a middle feed inlet of the dividing wall tower; 302. a discharge port at the top of the dividing wall tower; 303. a lateral line discharge port of the dividing wall tower; 304. a discharge hole at the bottom of the dividing wall tower; 4. a benzaldehyde rectifying tower; 401. a middle feed inlet of the benzaldehyde rectifying tower; 402. a discharge port at the top of the benzaldehyde rectifying tower; 403. a discharge hole at the bottom of the benzaldehyde rectifying tower; 404. a high boiling storage tank.
Detailed Description
The following detailed description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings, will make the advantages and features of the invention easier to understand by those skilled in the art, and thus will clearly and clearly define the scope of the invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
The invention provides a system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor, which has a schematic structural diagram as shown in figure 1 and comprises a jet loop reactor 1, a debenzolization tower 2, a dividing wall tower 3 and a benzaldehyde rectifying tower 4; the jet loop reactor 1 comprises a feed inlet, a high-
The feed inlets of the jet loop reactor 1 comprise a
The dividing wall tower 3 adopts a packed tower, and the packing comprises a tower top rectifying section, a middle rectifying section and a tower kettle stripping section; the tower top rectifying section is communicated with a tower
The top end of the high-
The invention also provides a method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor, which uses the system for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using the jet loop reactor to produce, and comprises the following steps:
s1, oxidation reaction: introducing inert gas into the top end of the jet loop reactor 1, and continuously adding the raw materials of toluene and the organic salt catalyst into the jet loop reactor 1; starting a loop circulating pump 102, controlling the jet flow rate, sucking oxygen into a venturi ejector 104 by using negative pressure formed by the venturi ejector 104, fully mixing and dispersing the oxygen and reaction materials, and spraying the oxygen and the reaction materials into a high-
s2, benzene removing treatment: inputting the reaction liquid obtained in the step S1 into a toluene removing tower 2, controlling the pressure of the top of the benzene removing tower 2 to be-65 to-75 kPa, so that toluene and water are output from the top of the tower, and the liquid of a toluene removing kettle is output from the bottom of the tower; after the toluene and the water output from the tower top are layered, the lower aqueous phase enters a
s3, dividing wall column separation treatment: inputting the demethylation kettle liquid obtained in the step S2 into a dividing wall tower 3, controlling the pressure of the tower top of the dividing wall tower 3 to be-88 to-95 kPa, so that a low-boiling mixture is output from the tower top in a steam form, after a high-boiling mixture is rectified, an obtained benzoic acid finished product with the purity of more than 99.5 percent is extracted from the tower side, and the residue of a rectifying kettle is output from the tower bottom; condensing steam output from the tower top to a reflux tank, refluxing one part of the steam to the tower top by a pump, and extracting the other part of the steam serving as mixed liquid containing benzaldehyde, wherein the content of the benzaldehyde in the mixed liquid is more than 60%;
s4, benzaldehyde rectification treatment: inputting the mixed solution containing benzaldehyde obtained in the step S2 into a benzaldehyde rectifying tower 4, controlling the pressure of the top of the benzaldehyde rectifying tower 4 to be-88 to-95 kPa, outputting the obtained benzaldehyde from the top of the tower, and outputting the rectifying kettle residue from the bottom of the tower; one part of the benzaldehyde output from the tower top is refluxed to the tower top through a pump, the other part of the benzaldehyde is taken as a benzaldehyde finished product to be extracted, and the purity of the benzaldehyde finished product is 99.9%.
In step S1, the jet flow speed is 50-70 m/S; the molar ratio of the toluene to the oxygen is (0.7-1.2) to 1; the pressure of the oxidation reaction is 0.3-0.8 MPa, the reaction temperature is 130-180 ℃, and the average residence time of the liquid phase substance in the jet loop reactor 1 is 0.5-1.5 h.
In step S2, the temperature of the demethanizer 2 is 180-220 ℃, the top temperature is 65-110 ℃, and the reflux ratio is (0.5-1.5): 1.
In step S3, the kettle temperature of the dividing wall tower 3 is 180-230 ℃, the top temperature is 110-160 ℃, the internal reflux distribution ratio is 1 (1-8), the light component reflux ratio is 10-40: 1, and the finished product reflux ratio is 1 (2-6).
In step S4, the temperature of the benzaldehyde rectification tower 4 is 110-160 ℃, the top temperature is 80-130 ℃, and the reflux ratio is (5-15): 1.
In step S1, the organic salt catalyst is one or more of organic salts of cobalt ions, manganese ions, and nickel ions.
The system and method for continuously producing high-quality and high-selectivity benzaldehyde and benzoic acid by using a jet loop reactor provided by the invention are described below with reference to the examples and the accompanying drawings.
- 上一篇：一种医用注射器针头装配设备
- 下一篇：一种芳香苄基酮的合成方法