A system and method for motorized adjustable oxidative co-production of acrolein and acrylic acid

Abstract

The application discloses a system and method for preparing propylene aldehyde and acrylic acid by motor-driven adjustable oxidation co-production, wherein the top of a propylene oxidation reactor is communicated with a preheater, the bottom of the propylene oxidation reactor is communicated with a deacidification tower, the upper part of the deacidification tower is provided with a pipeline for adding normal-temperature water, the top of the deacidification tower is communicated with an absorption tower, the bottom of the deacidification tower is communicated with a de-aldehyde tower, the top of the de-aldehyde tower is communicated with the absorption tower, the bottom of the de-aldehyde tower is communicated with azeotropic tower, the upper part of the absorption tower is provided with a pipeline for adding cold water, the bottom of the absorption tower is communicated with a rectifying tower, the top of the rectifying tower is communicated with the top of a propylene aldehyde storage tank, the bottom of the propylene aldehyde storage tank is communicated with the upper part of the rectifying tower, the top of the azeotropic tower is provided with a pipeline for adding an azeotropic agent, the bottom of the azeotropic tower is communicated with a de-heavy tower, the upper part of the azeotropic tower is communicated with an oil-water separator, the top of the oil-water separator is communicated with the top of the azeotropic tower, and the top of the de-heavy tower is communicated with an acrylic acid storage tank.

Description

Technical Field

[0001] This invention relates to the field of acrolein and acrylic acid preparation technology, and more particularly to a motorized and adjustable production apparatus and process for the co-production of acrolein and acrylic acid by selective oxidation of propylene. Background Technology

[0002] Acrolein is the simplest unsaturated aldehyde in terms of structure. It is chemically unstable and volatile, with a boiling point of 52.5℃. At room temperature and pressure, it is a pale yellow or colorless liquid and is readily soluble in water, acetone, and various organic solvents. Acrolein can be used to synthesize high-value-added chemical products such as methionine, glutaraldehyde, 1,3-propanediol, and 3-methylpyridine. It can also be used to produce acrolein polymers and can be directly used as a disinfectant and antibacterial agent.

[0003] Acrylic acid is an important basic raw material and high value-added product in modern chemical industry. It is a polar organic compound with unsaturated double bonds and carboxylic acid structure. Polymers made from acrylic acid have good viscosity, elasticity, light stability and aging resistance. Therefore, they are widely used in coatings, adhesives, textiles, brighteners, leather, detergents and other fields.

[0004] Existing technologies concerning the preparation facilities and methods of acrolein and / or acrylic acid, such as utility model patents with publication number CN214654564U and application number CN202120236602.2, disclose an apparatus for recovering acrolein from acrolein reaction waste liquid. This apparatus includes a fixed-bed reactor, a quench tower, an absorption tower, a stripping tower, a storage tank, a distillation tower, and an acrolein product tank. A storage tank is installed at the bottom of the stripping tower and connected to it via a circulation pump, allowing the stripping tower bottom liquid to form a cycle between the stripping tower bottom liquid and the storage tank. This increases the actual residence time of the bottom liquid and improves the yield of acrolein. The target product of this patent is acrolein.

[0005] For example, the invention application with publication number CN107108436A and application number CN201580068818.X discloses an acrylic acid manufacturing equipment, an acrylic acid manufacturing method, and a method for stopping the production of acrylic acid in the acrylic acid manufacturing method. The acrylic acid manufacturing equipment includes a raw material gasification device for converting liquefied propylene into propylene gas, an oxidation reaction device for converting propylene gas into crude acrylic acid, and a refining device for converting crude acrylic acid into acrylic acid. It can effectively utilize energy. The raw material gasification device has a heat transfer device inside and a heating device on the outer periphery, including at least the bottom of the raw material gasification device. The target product of this patent is acrylic acid.

[0006] For example, the invention application with publication number CN105461532A and application number CN201510833035.8 discloses a clean production method for preparing acrolein and acrylic acid by propylene oxidation. The method connects acrylic acid wastewater to an acrylic acid absorption tower, resulting in no waste gas or wastewater discharge. The acrylic acid in the wastewater is converted into acrylic acid products. During the acrylic acid refining process, an aqueous solution with more than 60% acrylic acid is obtained. Although this invention application can produce acrolein and acrylic acid simultaneously, it requires an additional acrylic acid reactor, and the process is relatively complex and costly. In addition, the flexibility of adjusting the two products, acrolein and acrylic acid, is limited. Furthermore, the purity of the acrylic acid products obtained in the three embodiments (99.5%, 99.2%, or 99.6%) is not very high, making it impossible to produce high-purity acrylic acid of not less than 99.8%, which makes it difficult to apply the acrylic acid to fields with higher purity requirements.

[0007] Existing systems that can simultaneously produce acrolein and / or acrylic acid often require an additional acrylic acid reactor, and the preparation process is complex and the production cost is high. More importantly, not only is the ability to adjust the mass ratio of acrolein and acrylic acid limited, but the purity of the acrylic acid product is also not very high. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a system and method for the co-production of acrolein and acrylic acid through oxidation. This method not only allows for greater flexibility in adjusting the mass ratio of the two products but also yields acrylic acid with higher purity. Furthermore, the process is simpler and less expensive.

[0009] The technical solution of this invention is as follows: A mobile, adjustable oxidation co-production system for acrolein and acrylic acid, comprising a propylene oxidation reactor, a deacidification tower, a dealdehyde removal tower, an absorption tower, a distillation tower, an azeotropic tower, an oil-water separator, a heavy metal removal tower, an acrolein storage tank, and an acrylic acid storage tank; wherein, the top of the propylene oxidation reactor is connected to a preheater via a pipeline, the bottom of the propylene oxidation reactor is connected to the deacidification tower via a pipeline, the upper part of the deacidification tower is provided with a pipeline for adding room temperature water, the top of the deacidification tower is connected to the absorption tower via a pipeline, and the bottom of the deacidification tower is connected to the dealdehyde removal tower via a pipeline. The top of the formaldehyde removal tower is connected to the absorption tower via a pipe, and the bottom of the formaldehyde removal tower is connected to the azeotropic tower via a pipe. The upper part of the absorption tower is connected to a pipe for adding cold water, and the bottom of the absorption tower is connected to the distillation tower via a pipe. The top of the distillation tower is connected to the top of the acrolein storage tank via a pipe, and the bottom of the acrolein storage tank is connected to the upper part of the distillation tower via a pipe. The top of the azeotropic tower is connected to a pipe for adding azeotropic agent, and the bottom of the azeotropic tower is connected to the de-heavyweight tower via a pipe. The upper part of the azeotropic tower is connected to the oil-water separator via a pipe, and the top of the oil-water separator is connected to the top of the azeotropic tower via a pipe. The top of the de-heavyweight tower is connected to the acrylic acid storage tank via a pipe.

[0010] The system for the combined production of acrolein and acrylic acid by the motorized adjustable oxidation process includes an oil-water separator with a pipe at the bottom that connects to the upper part of the deacidification tower.

[0011] The system for the combined production of acrolein and acrylic acid by the motorized and adjustable oxidation process includes a distillation column with a pipe at the bottom that connects to the upper part of the absorption column.

[0012] The system for the combined production of acrolein and acrylic acid by the motorized and adjustable oxidation process includes a pipe at the bottom of the distillation column that connects to the upper part of the deacidification column.

[0013] The system for the combined production of acrolein and acrylic acid by the motorized and adjustable oxidation process includes a first cooler connected to the formaldehyde removal tower and the acid removal tower via a pipeline.

[0014] The system for the combined production of acrolein and acrylic acid by the motorized and adjustable oxidation process includes a second cooler connected to the pipeline between the top of the distillation column and the top of the acrolein storage tank.

[0015] The system for the combined production of acrolein and acrylic acid by the motorized and adjustable oxidation process, wherein the azeotropic agent is benzene, n-hexane, or cyclohexane, or a mixture formed by any combination of these three.

[0016] A method for the co-production of acrolein and acrylic acid by a mobile and adjustable oxidation process, applied in a system for the co-production of acrolein and acrylic acid using only one propylene oxidation reactor, the method comprising the following steps: S210. Preheated propylene, air, and steam are piped into the propylene oxidation reactor. Under the action of a catalyst, propylene undergoes an oxidation reaction to produce acrolein and acrylic acid. The temperature of the reaction section of the propylene oxidation reactor is controlled between 280-355℃, and the temperature of the cooling section is controlled between 190-210℃. The volume ratio of propylene to air is dynamically adjusted between 0.125-0.167, so that the mass ratio of acrolein to acrylic acid in the material is between 4.0-10.0. The material exiting from the bottom of the propylene oxidation reactor is piped into the deacidification tower. S220. After the material enters the deacidification tower, room temperature water added from the top of the deacidification tower absorbs the acrylic acid in the material; the deacidified acrolein and a small amount of waste gas flow out from the top of the deacidification tower and enter the absorption tower through the pipeline, proceeding to step S240; acid water flows out from the bottom of the deacidification tower and enters the formaldehyde removal tower through the pipeline. S230. After the acid water enters the formaldehyde removal tower, the acrolein that is further removed flows out from the top of the formaldehyde removal tower and enters the absorption tower through the pipeline, proceeding to step S240; the material containing acrylic acid flows out from the bottom of the formaldehyde removal tower, proceeding to step S260. S240. The acrolein-containing materials flowing out from the top of the deacidification tower and the top of the dealdehyde removal tower enter the absorption tower. After the acrolein is absorbed by adding cold water, the acrolein-containing materials flow out from the bottom of the absorption tower and are heated to between 70-80°C before entering the distillation tower. S250. The heated acrolein-containing material enters the distillation column through a pipeline for separation. The temperature at the bottom of the distillation column is controlled between 99-101℃. The acrolein flows out from the top of the distillation column, and after cooling, it enters the acrolein storage tank. At the same time, the acrolein at the bottom of the acrolein storage tank is returned to the distillation column through a pipeline for secondary separation. S260: The acrylic acid-containing material flowing out from the bottom of the formaldehyde removal tower is divided into two parts. One part is cooled to 40-50℃ and then returned to the deacidification tower for secondary deacidification. The other part does not need to be cooled and enters the azeotropic tower through the pipeline. S270. Uncooled acrylic acid-containing material enters an azeotropic tower to remove moisture. The azeotropic temperature of the azeotropic tower is controlled between 85-90℃. Under the action of the azeotropic agent added from the top of the azeotropic tower, the water content of the material is reduced by utilizing the azeotropic principle. The dehydrated acrylic acid-containing material flows out from the bottom of the azeotropic tower and enters the de-heavy tower through a pipeline. The azeotropic agent and water enter the oil-water separator from the top of the azeotropic tower through a pipeline for oil-water separation. The separated azeotropic agent is returned to the azeotropic tower from the top of the oil-water separator for repeated recycling. S280. The material containing acrylic acid is further separated and the heavy components are removed in the deweighting tower, and the material enters the acrylic acid storage tank through a pipeline from the top of the deweighting tower.

[0017] The method for preparing acrolein and acrylic acid by motorized adjustable oxidation co-production, wherein in step S210, the temperature of the reaction section of the propylene oxidation reactor is controlled between 345-355℃.

[0018] The method for preparing acrolein and acrylic acid by motorized adjustable oxidation co-production, wherein in step S240, the temperature of the added cold water is controlled between 5-8°C, so that the temperature of the upper part of the absorption tower A3 is maintained between 8-12°C.

[0019] The present invention provides a system and method for the co-production of acrolein and acrylic acid using oxidation. This method generates acrolein and acrylic acid in a single reactor in one step. It not only allows for greater flexibility in adjusting the mass ratio of the two products, but also yields acrylic acid with a purity higher than 99.8% and a water content lower than 0.2%. Furthermore, it enables the recycling of wastewater, improving the resource utilization rate of the entire process and reducing wastewater discharge. The process is simpler and lower in cost. Attached Figure Description

[0020] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way; the shapes and proportions of the components in the drawings are merely illustrative and are intended to aid in understanding the invention, and are not intended to specifically limit the shapes and proportions of the components of the invention; those skilled in the art, under the guidance of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0021] Figure 1 This is a structural block diagram and process route diagram of a system embodiment for the oxidative co-production of acrolein and acrylic acid according to the present invention.

[0022] Summary of labels in the diagram: R, propylene oxidation reactor; A1, deacidification tower; A2, formaldehyde removal tower; A3, absorption tower; A4, distillation tower; A5, azeotropic tower; A6, oil-water separator; A7, heavy weight removal tower; B, acrolein storage tank; C, acrylic acid storage tank; D1, first cooler; D2, second cooler; (S1, S2, and S3) Stream (i.e., wastewater). Implementation

[0023] The specific embodiments and examples of the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described are only used to explain the present invention and are not intended to limit the specific embodiments of the present invention.

[0024] like Figure 1 As shown, the system for the combined oxidation and production of acrolein and acrylic acid of the present invention consists of a propylene oxidation reactor R, a deacidification tower A1, a dealdehyde removal tower A2, an absorption tower A3, a distillation tower A4, an azeotropic tower A5, an oil-water separator A6, a heavy removal tower A7, an acrolein storage tank B, and an acrylic acid storage tank C.

[0025] The top of the propylene oxidation reactor R is connected to a preheater (not shown in the figure) via a pipe, which is used to allow propylene, air, and water vapor heated by the preheater to enter the propylene oxidation reactor R. The propylene oxidation reactor R consists of a reaction section and a quench section. The reaction section is located at the top of the propylene oxidation reactor R, and the quench section is located at the bottom of the propylene oxidation reactor R, which is used to rapidly cool the material coming out of the reaction section. The bottom of the propylene oxidation reactor R is connected to the deacidification tower A1 via a pipe, which is used to feed the material coming out of the quench section of the propylene oxidation reactor R into the deacidification tower A1.

[0026] The upper part of the deacidification tower A1 is equipped with a pipe for adding room temperature water. The top of the deacidification tower A1 is connected to the absorption tower A3 through a pipe, which is used to input acrolein and waste gas (containing a small amount of carbon dioxide and unreacted propylene) into the absorption tower A3. The bottom of the deacidification tower A1 is connected to the deformaldehyde tower A2 through a pipe, which is used to input acid water (containing a small amount of acetic acid) into the deformaldehyde tower A2.

[0027] The top of the formaldehyde removal tower A2 is connected to the absorption tower A3 via a pipe, which is used to input the acrolein after formaldehyde removal into the absorption tower A3. The bottom of the formaldehyde removal tower A2 is connected to the azeotropic tower A5 via a pipe, which is used to input the material containing acrylic acid into the azeotropic tower A5. Preferably, the formaldehyde removal tower A2 and the deacidification tower A1 are also connected by a first cooler D1 via a pipe, which is used to rapidly cool the part of the material containing acrylic acid before returning it to the deacidification tower A1 for secondary deacidification.

[0028] The upper part of the absorption tower A3 is connected to a pipe for adding cold water, and the bottom of the absorption tower A3 is connected to the distillation tower A4 through a pipe for heating the acrolein-containing material and then feeding it into the distillation tower A4.

[0029] The top of distillation column A4 is connected to the top of acrolein storage tank B via a pipe, which is used to cool the separated acrolein before it is fed into acrolein storage tank B. Preferably, a second cooler D2 is also connected to the pipe between the top of distillation column A4 and the top of acrolein storage tank B, which is used to rapidly cool the separated acrolein. Furthermore, the bottom of acrolein storage tank B is connected to the top of distillation column A4 via a pipe, which is used to return the acrolein at the bottom of acrolein storage tank B to distillation column A4 for secondary separation, thereby improving the purity of acrolein and reducing its water content.

[0030] The top of the azeotropic tower A5 is connected to a pipe for adding the azeotropic agent, and the bottom of the azeotropic tower A5 is connected to the dehydration tower A7 through a pipe for feeding the dehydrated acrylic acid-containing material into the dehydration tower A7; the upper part of the azeotropic tower A5 is connected to the oil-water separator A6 through a pipe for feeding the azeotropic agent and water into the oil-water separator A6.

[0031] Benzene, n-hexane, or cyclohexane can be used as azeotropic agents, or a mixture of any combination of these three can be used as an azeotropic agent.

[0032] The top of the oil-water separator A6 is connected to the top of the azeotropic tower A5 via a pipeline (or connected to a pipeline for adding the azeotropic agent) to return the separated azeotropic agent to the azeotropic tower A5 for recycling.

[0033] The top of the deweighting tower A7 is connected to the acrylic acid storage tank C via a pipeline, which is used to input the separated acrylic acid into the acrylic acid storage tank C.

[0034] To reduce wastewater discharge in the system for the combined oxidation and production of acrolein and acrylic acid in this invention, making it a more environmentally friendly production system and achieving full utilization of water resources, at least one of the following improvement measures can be taken: One method is to install a pipe at the bottom of the oil-water separator A6 that connects to the top of the deacidification tower A1 (or connects to a pipe for adding room temperature water), to process the separated water (such as...) Figure 1The material S1 shown is returned to the deacidification tower A1 for recycling; Secondly, a pipe is installed at the bottom of distillation column A4 that connects to the upper part of absorption column A3 (or to a pipe for adding cold water) to facilitate the removal of the separated water (such as...). Figure 1 The material flow S2 shown is returned to the absorption tower A3 for recycling; Third, a pipe is installed at the bottom of distillation column A4 that connects to the upper part of deacidification column A1 (or to a pipe used for adding room temperature water) to transfer the separated water (such as...) Figure 1 The logistics S3 shown is returned to the deacidification tower A1 for recycling.

[0035] like Figure 1 As shown, the method for the co-production of acrolein and acrylic acid by oxidation of the present invention is applied in a system for the co-production of acrolein and acrylic acid by oxidation of only one propylene oxidation reactor, and includes the following steps: S210. Preheated propylene, air, and steam are piped into the propylene oxidation reactor R. Under the action of a catalyst, propylene undergoes an oxidation reaction to produce acrolein and acrylic acid. The temperature of the reaction section of the propylene oxidation reactor R is controlled between 280-355℃, with the optimal temperature between 345-355℃. The temperature of the cooling section of the propylene oxidation reactor R is controlled between 190-210℃. The material exiting from the bottom of the propylene oxidation reactor R is piped into the deacidification tower A1. The volume ratio of propylene to air is dynamically adjusted by a flow meter between 0.125-0.167, so that the mass ratio of acrolein to acrylic acid in the material is between 4.0-10.0. As the volume ratio of propylene to air increases, the mass percentage of acrolein gradually increases.

[0036] S220. After the material enters the deacidification tower A1, room temperature water added from the top of the deacidification tower A1 can absorb the acrylic acid in the material; the deacidified acrolein and a small amount of waste gas (i.e. carbon dioxide) flow out from the top of the deacidification tower A1 at a temperature between 58-62℃, and enter the absorption tower A3 through a pipeline, proceeding to step S240; the acid water flows out from the bottom of the deacidification tower A1 at a temperature between 73-77℃, and enters the formaldehyde removal tower A2 through a pipeline. S230. After the acid water enters the formaldehyde removal tower A2, the acrolein that is further removed flows out from the top of the formaldehyde removal tower A2 at a temperature between 59-62°C and enters the absorption tower A3 through a pipe, proceeding to step S240; the acrylic acid-containing material flows out from the bottom of the formaldehyde removal tower A2 at a temperature between 72-77°C and proceeds to step S260. S240. The acrolein-containing materials flowing out from the top of the deacidification tower A1 and the top of the formaldehyde removal tower A2 both enter the absorption tower A3. The acrolein is absorbed by adding cold water at a lower temperature. For example, the temperature of the added fresh cold water is controlled between 5-8°C, so that the temperature of the upper part of the absorption tower A3 is maintained between 8-12°C. The acrolein-containing materials flow out from the bottom of the absorption tower A3 at a temperature between 30-32°C and acrolein concentration between 4-6%. Before entering the distillation tower A4, the temperature is heated to between 70-80°C. S250. The heated acrolein-containing material enters the distillation column A4 through a pipeline for separation. The temperature at the bottom of the distillation column A4 is controlled between 99-101℃. The acrolein flows out from the top of the distillation column A4 at a temperature between 49-54℃. After being cooled by the second cooler D2 (e.g., to room temperature), it enters the acrolein storage tank B. Simultaneously, the acrolein at the bottom of the acrolein storage tank B is returned to the distillation column A4 through a pipeline for secondary separation. After the system stabilizes, acrolein with a purity of not less than 98.5% and a water content of less than 1.5% can be obtained. S260. The acrylic acid-containing material flowing out from the bottom of the formaldehyde removal tower A2 is divided into two parts. One part is cooled to 40-50°C by the first cooler D1 and then returned to the deacidification tower A1 for secondary deacidification. The other part does not need to be cooled and enters the azeotropic tower A5 through the pipeline. S270. Uncooled acrylic acid-containing material enters azeotropic tower A5 to remove moisture. The azeotropic temperature of azeotropic tower A5 is controlled between 85-90℃. Under the action of the azeotropic agent added from the top of azeotropic tower A5, the water content of the material is reduced by utilizing the azeotropic principle, so that the water content of acrylic acid is less than 0.2%. After dehydration, the acrylic acid-containing material flows out from the bottom of azeotropic tower A5 and enters the de-heavy tower A7 through a pipeline. The azeotropic agent and water enter the oil-water separator A6 from the top of azeotropic tower A5 through a pipeline for oil-water separation. The separated azeotropic agent is returned to azeotropic tower A5 from the top of oil-water separator A6 for repeated recycling. S280. The material containing acrylic acid is further separated and heavy components are removed in the deweighting tower A7 to obtain acrylic acid with a purity of higher than 99.8% and a water content of less than 0.2%, which is then piped from the top of the deweighting tower A7 into the acrylic acid storage tank C.

[0037] Example 1: Acrylonitrile with a purity of 98.5% and acrylic acid with a purity higher than 99.8% can be obtained. The temperature of the reaction section of the propylene oxidation reactor R is controlled at 345℃, and the temperature of its cooling section is controlled at 210℃. The volume ratio of propylene to air is adjusted to 0.125, so that the mass ratio of acrolein to acrylic acid in the material is 4. The temperature of the material exiting from the bottom of the propylene oxidation reactor R is 205℃. The deacidified acrolein and a small amount of waste gas flow out from the top of the deacidification tower A1 at a temperature of 62℃, and the temperature of the acid water flowing out from the bottom of the deacidification tower A1 is 77℃. The temperature of the acrolein flowing out from the top of the deformaldehyde removal tower A2 is 62℃, and the material containing acrylic acid flows out from the bottom of the deformaldehyde removal tower A2. The material flowing out has a temperature of 77°C and is cooled to 46°C for secondary deacidification in the return deacidification tower A1. The temperature of the cold water added from the top of the absorption tower A3 is controlled at 6°C. The material containing acrolein flowing out from the bottom of the absorption tower A3 has a temperature of 32°C and acrolein concentration of 4.5%. The material containing acrolein is heated to 75°C before entering the distillation tower A4. The acrolein flowing out from the top of the distillation tower A4 has a temperature of 54°C and is cooled to 25°C before entering the acrolein storage tank B. Cyclohexane is added to the azeotropic tower A5 as an azeotropic agent to control the azeotropic temperature of the azeotropic tower A5 at 86°C.

[0038] Example 2: Acrylonitrile with a purity of 98.6% and acrylic acid with a purity higher than 99.9% and a water content of less than 0.1% can be obtained. The temperature of the reaction section of the propylene oxidation reactor R is controlled at 355℃, and the temperature of its cooling section is controlled at 195℃. The volume ratio of propylene to air is adjusted to 0.167, so that the mass ratio of acrolein to acrylic acid in the material is 10. The material temperature exiting from the bottom of the propylene oxidation reactor R is 195℃. The acrolein after deacidification and a small amount of waste gas flow out from the top of the deacidification tower A1 at a temperature of 59℃, and the acid water flowing out from the bottom of the deacidification tower A1 at a temperature of 73℃. The acrolein flowing out from the top of the deformaldehyde removal tower A2 at a temperature of 59℃, and the material containing acrylic acid flows out from the bottom of the deformaldehyde removal tower A2 at a temperature of 73℃. The temperature of the acrolein-containing material flowing out of the bottom of the absorption tower A3 is controlled at 8°C, and the temperature of the material undergoing secondary deacidification in the return deacidification tower A1 is 30°C with acrolein concentration of 5%. The acrolein-containing material is heated to 78°C before entering the distillation tower A4, and the temperature of the acrolein flowing out of the top of the distillation tower A4 is 52°C. After cooling to 30°C, it enters the acrolein storage tank B. A mixture of cyclohexane and benzene is added to the azeotropic tower A5 as an azeotropic agent with a mass ratio of cyclohexane to benzene of 1:1, and the azeotropic temperature of the azeotropic tower A5 is controlled at 88°C.

[0039] It should be noted that the system and method for the oxidative co-production of acrolein and acrylic acid of the present invention do not achieve simple functions with complex structures or complicated steps, nor do they use conventional or simple features for combination or stacking. They are in line with the common sense of technological improvement in the industry and have certain application value.

[0040] Any content not described in detail in this specification is prior art known to those skilled in the art.

[0041] It should be understood that the above description is only a preferred embodiment of the present invention and is not sufficient to limit the technical solution of the present invention. For those skilled in the art, within the spirit and principles of the present invention, additions, subtractions, substitutions, transformations or improvements can be made based on the above description, and all such additions, subtractions, substitutions or improvements should fall within the protection scope of the appended claims of the present invention.

Claims

1. A system for the coordinated oxidation of acrolein and acrylic acid, characterized in that, It consists of a propylene oxidation reactor, an acid removal tower, a formaldehyde removal tower, an absorption tower, a distillation tower, an azeotropic tower, an oil-water separator, a heavy metal removal tower, an acrolein storage tank, and an acrylic acid storage tank. The top of the propylene oxidation reactor is connected to a preheater via a pipeline, and the bottom of the reactor is connected to the acid removal tower via a pipeline. The upper part of the acid removal tower is equipped with a pipeline for adding ambient temperature water. The top of the acid removal tower is connected to the absorption tower via a pipeline, and the bottom of the acid removal tower is connected to the formaldehyde removal tower via a pipeline. The top of the formaldehyde removal tower is connected to the absorption tower via a pipeline. The bottom of the formaldehyde removal tower is connected to the azeotropic tower via a pipe. The upper part of the absorption tower is connected to a pipe for adding cold water. The bottom of the absorption tower is connected to the distillation tower via a pipe. The top of the distillation tower is connected to the top of the acrolein storage tank via a pipe. The bottom of the acrolein storage tank is connected to the upper part of the distillation tower via a pipe. The top of the azeotropic tower is connected to a pipe for adding azeotropic agents. The bottom of the azeotropic tower is connected to the de-heavyweight tower via a pipe. The upper part of the azeotropic tower is connected to the oil-water separator via a pipe. The top of the oil-water separator is connected to the top of the azeotropic tower via a pipe. The top of the de-heavyweight tower is connected to the acrylic acid storage tank via a pipe.

2. The system for the coordinated oxidation and co-production of acrolein and acrylic acid according to claim 1, characterized in that: The bottom of the oil-water separator is equipped with a pipe that connects to the upper part of the deacidification tower.

3. The system for the coordinated oxidation and co-production of acrolein and acrylic acid according to claim 1, characterized in that: The bottom of the distillation column is equipped with a pipe that connects to the upper part of the absorption column.

4. The system for the combined production of acrolein and acrylic acid by mobile, adjustable oxidation according to claim 1, characterized in that: The bottom of the distillation column is equipped with a pipe that connects to the upper part of the deacidification column.

5. The system for the co-production of acrolein and acrylic acid by mobile adjustable oxidation according to claim 1, characterized in that: The formaldehyde removal tower and the acid removal tower are connected by a pipeline and a first cooler is provided.

6. The system for the co-production of acrolein and acrylic acid by mobile adjustable oxidation according to claim 1, characterized in that: A second cooler is connected to the pipeline between the top of the distillation column and the top of the acrolein storage tank.

7. The system for the co-production of acrolein and acrylic acid by mobile adjustable oxidation according to claim 1, characterized in that: The azeotropic agent is benzene, n-hexane, or cyclohexane, or a mixture of any combination of these three.

8. A method for the co-production of acrolein and acrylic acid by motorized adjustable oxidation, characterized in that, The method is carried out in any one of the motorized adjustable oxidation co-production systems for the preparation of acrolein and acrylic acid according to any one of claims 1 to 7, and the method includes the following steps: S210. Preheated propylene, air, and steam are piped into the propylene oxidation reactor. Under the action of a catalyst, propylene undergoes an oxidation reaction to produce acrolein and acrylic acid. The temperature of the reaction section of the propylene oxidation reactor is controlled between 280-355℃, and the temperature of the cooling section is controlled between 190-210℃. The volume ratio of propylene to air is dynamically adjusted between 0.125-0.167, so that the mass ratio of acrolein to acrylic acid in the material is between 4.0-10.

0. The material exiting from the bottom of the propylene oxidation reactor is piped into the deacidification tower. S220. After the material enters the deacidification tower, room temperature water added from the top of the deacidification tower absorbs the acrylic acid in the material; the deacidified acrolein and a small amount of waste gas flow out from the top of the deacidification tower and enter the absorption tower through the pipeline, proceeding to step S240; acid water flows out from the bottom of the deacidification tower and enters the formaldehyde removal tower through the pipeline. S230. After the acid water enters the formaldehyde removal tower, the acrolein that is further removed flows out from the top of the formaldehyde removal tower and enters the absorption tower through the pipeline, proceeding to step S240; the material containing acrylic acid flows out from the bottom of the formaldehyde removal tower, proceeding to step S260. S240. The acrolein-containing materials flowing out from the top of the deacidification tower and the top of the dealdehyde removal tower enter the absorption tower. After the acrolein is absorbed by adding cold water, the acrolein-containing materials flow out from the bottom of the absorption tower and are heated to between 70-80°C before entering the distillation tower. S250. The heated acrolein-containing material enters the distillation column through a pipeline for separation. The temperature at the bottom of the distillation column is controlled between 99-101℃. The acrolein flows out from the top of the distillation column, and after cooling, it enters the acrolein storage tank. At the same time, the acrolein at the bottom of the acrolein storage tank is returned to the distillation column through a pipeline for secondary separation. S260: The acrylic acid-containing material flowing out from the bottom of the formaldehyde removal tower is divided into two parts. One part is cooled to 40-50℃ and then returned to the deacidification tower for secondary deacidification. The other part does not need to be cooled and enters the azeotropic tower through the pipeline. S270. Uncooled acrylic acid-containing material enters an azeotropic tower to remove moisture. The azeotropic temperature of the azeotropic tower is controlled between 85-90℃. Under the action of the azeotropic agent added from the top of the azeotropic tower, the water content of the material is reduced by utilizing the azeotropic principle. The dehydrated acrylic acid-containing material flows out from the bottom of the azeotropic tower and enters the de-heavy tower through a pipeline. The azeotropic agent and water enter the oil-water separator from the top of the azeotropic tower through a pipeline for oil-water separation. The separated azeotropic agent is returned to the azeotropic tower from the top of the oil-water separator for repeated recycling. S280. The material containing acrylic acid is further separated and the heavy components are removed in the deweighting tower, and the material enters the acrylic acid storage tank through a pipeline from the top of the deweighting tower.

9. The method for preparing acrolein and acrylic acid by motorized adjustable oxidation co-production according to claim 8, characterized in that: In step S210, the temperature of the reaction section of the propylene oxidation reactor is controlled between 345-355℃.

10. The method for preparing acrolein and acrylic acid by motorized adjustable oxidation co-production according to claim 8, characterized in that: In step S240, the temperature of the added cold water is controlled between 5-8℃, so that the temperature at the top of the absorption tower is maintained between 8-12℃.

Images