Acrylic acid extraction treatment process and application

Abstract

The invention relates to the technical field of acrylic acid-containing waste water recovery, in particular to an acrylic acid extraction treatment process and application, the acrylic acid extraction treatment process comprises the following steps: S1, introducing acrylic acid-containing waste water from an upper feed port of an extraction tower, introducing an extraction agent from a lower feed port of the extraction tower, the acrylic acid-containing wastewater and an extraction agent are subjected to countercurrent exchange extraction, an extraction phase is discharged from the top of an extraction tower and enters a rectifying tower for dehydration treatment, a raffinate phase is discharged from the bottom of the extraction tower for sewage treatment, and the extraction agent comprises 2-ethylhexanol; s2, steam is discharged from the top of the rectifying tower, after condensation, one part of condensate serves as rectifying tower backflow liquid to flow back, the other part of condensate serves as tower top distillate to be discharged for sewage treatment, an extraction agent solution containing acrylic acid is discharged from the bottom of the rectifying tower, and one part of the extraction agent solution containing acrylic acid circularly enters a reboiler; and the other part of the extraction agent solution containing acrylic acid is recycled as a product. The 2-ethylhexanol can efficiently extract acrylic acid in the acrylic acid-containing wastewater, and the dehydrated extract phase is directly used in the preparation of 2-ethylhexyl acrylate.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic acid-containing wastewater recovery, and in particular to an acrylic acid extraction treatment process and application. Background Art

[0002] Acrylic acid and acrylic acid esters are extremely important raw materials and intermediates for organic chemical industry, and are high value-added petrochemical products that can be further processed into a variety of fine chemical products. They have shown excellent application prospects in many fields such as adhesives, coatings, plastics, textiles, papermaking, leather chemicals, elastomers, printing, synthetic fibers, super absorbent resins, UV / EB curing, building materials, flocculants, additives industry, detergent industry, etc.

[0003] The synthesis process of acrylic acid is a two-step propylene oxidation process, which uses water to absorb acrylic acid in the reaction gas and then undergoes dehydration, deacetic acid removal, and deweighting processes. During the dehydration process, a large amount of acid-containing wastewater is generated. The acid-containing wastewater contains 2.0% acrylic acid, and this part of high-concentration wastewater is currently directly sent to sewage biochemical treatment.

[0004] The synthesis process of butyl acrylate is a direct esterification method between acid and alcohol. Acrylic acid and excess butanol undergo esterification reaction in an esterification reactor, and then high-purity acrylate products are obtained through extraction, neutralization, light removal, heavy removal and other processes. In the neutralization washing, the residual methanesulfonic acid and acrylic acid are neutralized by adding NaOH, generating a large amount of saline wastewater. After filtering, the saline wastewater is desalted / concentrated by ion membrane and decomposed by bipolar membrane to obtain 10%wt acrylic acid aqueous solution, which is directly sent to the esterification reactor for reuse, consuming a large amount of steam.

[0005] Therefore, an effective acrylic acid extraction process is needed to treat acrylic acid-containing wastewater, fully utilize the acrylic acid in the wastewater, and reduce wastewater treatment consumption. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the treatment of acrylic acid-containing wastewater described in the above background technology requires a large amount of resources to be consumed. An acrylic acid extraction treatment process and application are proposed herein. The acrylic acid extraction treatment process can fully extract and utilize acrylic acid in wastewater, thereby reducing the consumption of subsequent wastewater treatment.

[0007] The technical solution adopted by the present invention to solve the technical problem is: an extraction process of acrylic acid, the extraction process comprising the following steps:

[0008] S1, introducing acrylic acid-containing wastewater into the upper feed port of the extraction tower, introducing an extractant into the lower feed port of the extraction tower, the acrylic acid-containing wastewater and the extractant are subjected to countercurrent exchange extraction, the extract phase is discharged from the top of the extraction tower and enters the distillation tower for dehydration treatment, and the raffinate phase is discharged from the bottom of the extraction tower for sewage treatment,

[0009] The extractant comprises 2-ethylhexanol;

[0010] S2. Steam is discharged from the top of the distillation tower. After condensation, a part of the condensate is refluxed as the distillation tower reflux liquid, and the other part of the condensate is discharged as the top distillate for sewage treatment. An extractant solution containing acrylic acid is discharged from the bottom of the distillation tower, a part of the extractant solution containing acrylic acid is circulated into the reboiler, and the other part of the extractant solution containing acrylic acid is recovered as a product.

[0011] The invention adopts an extraction tower and a distillation tower to carry out extraction and distillation treatment on acrylic acid-containing wastewater, and acrylic acid can be extracted and recovered by using only an extractant containing 2-ethylhexanol. The extraction phase is dehydrated by distillation to obtain a mixture of the extractant and acrylic acid, and the mixture can be directly used as a raw material for 2-ethylhexyl acrylate. The invention has high efficiency and does not require a large amount of electricity or steam to be consumed during the extraction and distillation process, which is in line with the concept of green energy saving.

[0012] Preferably, the acrylic acid-containing wastewater comprises acrylic acid and water. Further, the acrylic acid-containing wastewater preferably comprises 2-10 wt % of acrylic acid and 90-98 wt % of water.

[0013] In the present invention, the acrylic acid-containing wastewater can be obtained by filtering, desalting and bipolar membrane decomposing the sodium acrylate-containing wastewater in the production process of butyl acrylate; or the acid-containing wastewater produced in the dehydration process of acrylic acid synthesis process. 2-ethylhexanol can be used as a high-efficiency extractant for the acrylic acid and water mixed system.

[0014] Preferably, in step S1, the mass flow rate ratio of the extractant to the wastewater containing acrylic acid is (1-5):1. Further, the mass flow rate of the extractant to the wastewater containing acrylic acid is preferably (1.1-1.8):1.

[0015] Preferably, in step S1, the pressure at the top of the extraction tower is 20-30 KPa (A).

[0016] Preferably, in step S2, the top temperature of the distillation tower is 30-50°C, and the bottom temperature of the distillation tower is 50-80°C. Furthermore, the top temperature of the distillation tower is preferably 30-35°C, and the bottom temperature of the distillation tower is preferably 50-55°C.

[0017] Preferably, in step S2, the reflux ratio of the distillation tower top is 1-3, and further, the reflux ratio of the distillation tower top is preferably 1.5-2.

[0018] Preferably, in step S2, the pressure of the distillation tower is 15-30 KPa (A).

[0019] Preferably, in step S2, the number of plates of the distillation tower is 10-30.

[0020] Preferably, the recovery rate of acrylic acid is greater than 95%.

[0021] An application of the above extraction process in the production of 2-ethylhexyl acrylate, wherein the extractant solution containing acrylic acid obtained by the extraction process is used as a raw material for preparing 2-ethylhexyl acrylate.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention proposes to use 2-ethylhexanol as an extractant to extract and recover acrylic acid from wastewater containing acrylic acid. The recovery rate of acrylic acid is as high as over 95%, with high recovery rate and low energy consumption.

[0024] 2. The present invention finally obtains an extractant solution containing acrylic acid, that is, a mixture of acrylic acid and 2-ethylhexanol, and is linked to a preparation method of 2-ethylhexyl acrylate. The extraction and distillation product is used as a raw material to generate 2-ethylhexyl acrylate, so that acrylic acid is fully recovered and utilized, which has great economic and environmental benefits.

[0025] 3. The extraction tower and distillation tower required for the extraction process of the present invention are both existing equipment, and there is no need to improve the equipment, the required investment is small, and the extraction process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 The present invention is a process flow chart of the extraction treatment process of acrylic acid. DETAILED DESCRIPTION

[0028] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] The present invention is now further described in conjunction with specific examples. The following examples are only for explaining the present invention, but do not constitute a limitation of the present invention. The test samples and test processes used in the following examples include the following (if the specific experimental conditions are not indicated in the examples, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, if not otherwise specified, can all be obtained from commercial channels).

[0031] Example 1

[0032] An extraction process for acrylic acid, the specific steps of the extraction process are as follows:

[0033] S1. 9500kg / h of salt-containing (sodium acrylate) wastewater generated in the production process of butyl acrylate is filtered and treated with ion membrane desalination, concentration and bipolar membrane decomposition technology to obtain acrylic acid-containing wastewater. The specific components of the acrylic acid-containing wastewater are as follows: 10wt% acrylic acid and 90wt% water.

[0034] S2, introducing acrylic acid-containing wastewater at a flow rate of 2.8 t / h into the upper feed port of the extraction tower, introducing 2-ethylhexanol at a flow rate of 5 t / h into the lower feed port of the extraction tower, the acrylic acid-containing wastewater and 2-ethylhexanol are subjected to countercurrent exchange extraction in the extraction tower, the acrylic acid in the acrylic acid-containing wastewater enters the 2-ethylhexanol, the extract phase is discharged from the top of the extraction tower and enters the distillation tower for dehydration treatment, and the raffinate phase is discharged from the bottom of the extraction tower for sewage treatment,

[0035] The flow rate of the raffinate phase is 2403 kg / h, and the components are 0.50 wt% acrylic acid and 99.50 wt% water;

[0036] The flow rate of the extract phase is 5397 kg / h, and the components are 4.97 wt% acrylic acid, 2.39 wt% water and 92.64 wt% 2-ethylhexanol;

[0037] The operating pressure of the extraction tower is 20Kpa and the operating temperature is room temperature.

[0038] S3, the extract phase is subjected to vacuum distillation in the distillation tower, water and a small amount of acrylic acid are evaporated from the top of the distillation tower and enter the condenser for condensation, the condensate enters the reflux tank, the non-condensable gas enters the water ring vacuum pump, part of the condensate is used as the reflux liquid of the distillation tower, and the other part of the condensate is discharged as the top distillate for wastewater treatment; part of the bottom liquid is circulated into the reboiler, and the bottom temperature is controlled by heating with 0.20MPaG steam, and the other part of the bottom liquid is used as the product output,

[0039] The flow rate of the overhead product is 129 kg / h, and the composition is 0.10 wt% acrylic acid and 99.90 wt% water;

[0040] The product flow rate is 5268 kg / h, and the composition is 5.09 wt% acrylic acid and 94.91 wt% 2-ethylhexanol;

[0041] The operating pressure of the distillation tower is 15Kpa, the reflux ratio of the distillation tower top is 1.5, the distillation tower top temperature is 35℃, and the distillation tower kettle temperature is 55℃.

[0042] The recovery rate of the acrylic acid is 95.7%.

[0043] As can be seen from the above Example 1, the present invention only uses 2-ethylhexanol as an extractant to extract acrylic acid from acrylic acid-containing wastewater, thereby achieving efficient extraction of acrylic acid, with an extraction recovery rate of up to 95.7%, and the recovered acrylic acid and 2-ethylhexanol mixed solution can be directly used as a raw material for preparing 2-ethylhexyl acrylate, thereby making full use of the wastewater containing acrylic acid.

[0044] Example 2

[0045] An extraction process for acrylic acid, the specific steps of the extraction process are as follows:

[0046] S1. The synthesis process of acrylic acid is a two-step oxidation method of propylene, which uses water to absorb acrylic acid in the reaction gas, and undergoes dehydration, deacetic acid removal, and deweighting processes. In the dehydration process, a large amount of acrylic acid-containing wastewater is generated. The specific components of the acrylic acid-containing wastewater are as follows: 2wt% acrylic acid and 98wt% water.

[0047] S2, introducing acrylic acid-containing wastewater at a flow rate of 6.6 t / h into the upper feed port of the extraction tower, introducing an extractant at a flow rate of 7 t / h into the lower feed port of the extraction tower, the acrylic acid-containing wastewater and the extractant are subjected to countercurrent exchange extraction in the extraction tower, the acrylic acid in the acrylic acid-containing wastewater enters the extractant, the extract phase is discharged from the top of the extraction tower and enters the distillation tower for dehydration treatment, and the raffinate phase is discharged from the bottom of the extraction tower for sewage treatment,

[0048] The specific components of the extractant are as follows: 55.0 wt% of 2-ethylhexanol, 15.0 wt% of toluene, and 55.0 wt% of 2-ethylhexyl acrylate;

[0049] The flow rate of the raffinate phase is 6600 kg / h, and the components are 0.30 wt% acrylic acid and 99.70 wt% water;

[0050] The flow rate of the extract phase is 7770 kg / h, and the components are 1.5 wt% acrylic acid, 2.0 wt% water, 53.1 wt% 2-ethylhexanol, 29.0 wt% 2-ethylhexyl acrylate and 14.5 wt% toluene;

[0051] The operating pressure of the extraction tower is 30Kpa and the operating temperature is room temperature.

[0052] S3, the extract phase is subjected to vacuum distillation in the distillation tower, water and a small amount of acrylic acid are evaporated from the top of the distillation tower and enter the condenser for condensation, the condensate enters the reflux tank, the non-condensable gas enters the water ring vacuum pump, the condensate is allowed to stand for stratification, the toluene layer is used as the reflux liquid of the distillation tower, the remaining liquid layer of the condensate is discharged as the top distillate for wastewater treatment; a part of the bottom liquid is circulated into the reboiler, and the bottom temperature is controlled by heating with 0.20MPaG steam, and the other part of the bottom liquid is used as the product output,

[0053] The flow rate of the overhead distillate is 155 kg / h, and the composition is 0.10 wt% acrylic acid and 99.90 wt% water;

[0054] The product flow rate is 7614 kg / h, and the components are 1.5 wt% acrylic acid, 54.2 wt% 2-ethylhexanol, 14.8 wt% toluene and 29.5 wt% 2-ethylhexyl acrylate;

[0055] The operating pressure of the distillation tower is 30Kpa, the reflux ratio of the distillation tower top is 1.9, the temperature of the distillation tower top is 30℃, and the temperature of the distillation tower bottom is 50℃.

[0056] The recovery rate of the acrylic acid is: 86.5%.

[0057] In the above Example 2, the present invention uses the existing material containing 2-ethylhexanol in the factory as an extractant to extract acrylic acid from acrylic acid-containing wastewater. When the concentration of 2-ethylhexanol in the extractant is low, acrylic acid can still be effectively extracted, and the extraction recovery rate can reach 86.5%.

[0058] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0059] The above is a detailed introduction to the extraction treatment process and application of acrylic acid provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An extraction process for acrylic acid, characterized in that: The extraction process comprises the following steps: S1, introducing acrylic acid-containing wastewater into the upper feed port of the extraction tower, introducing an extractant into the lower feed port of the extraction tower, the acrylic acid-containing wastewater and the extractant are subjected to countercurrent exchange extraction, the extract phase is discharged from the top of the extraction tower and enters the distillation tower for dehydration treatment, and the raffinate phase is discharged from the bottom of the extraction tower for sewage treatment, The extractant comprises 2-ethylhexanol; S2. Steam is discharged from the top of the distillation tower. After condensation, a part of the condensate is refluxed as the distillation tower reflux liquid, and the other part of the condensate is discharged as the top distillate for sewage treatment. An extractant solution containing acrylic acid is discharged from the bottom of the distillation tower, a part of the extractant solution containing acrylic acid is circulated into the reboiler, and the other part of the extractant solution containing acrylic acid is recovered as a product.

2. The extraction process according to claim 1, characterized in that: The acrylic acid-containing wastewater includes acrylic acid and water.

3. The extraction process according to claim 1, characterized in that: In step S1, the mass flow ratio of the extractant to the acrylic acid-containing wastewater is (1-5):

1.

4. The extraction process according to claim 1, characterized in that: In step S1, the pressure at the top of the extraction tower is 20-30 KPa (A).

5. The extraction process according to claim 1, characterized in that: In step S2, the top temperature of the distillation tower is 30-50°C, and the bottom temperature of the distillation tower is 50-80°C.

6. The extraction process according to claim 1, characterized in that: In step S2, the reflux ratio of the distillation tower top is 1-3.

7. The extraction process according to claim 1, characterized in that: In step S2, the pressure of the distillation tower is 15-30 KPa (A).

8. The extraction process according to claim 1, characterized in that: In step S2, the number of plates of the distillation tower is 10-30.

9. The extraction process according to claim 1, characterized in that: The recovery rate of the acrylic acid is greater than or equal to 95%.

10. An application of the extraction treatment process according to any one of claims 1 to 9 in the production of 2-ethylhexyl acrylate, characterized in that: The acrylic acid-containing extractant solution is directly used as a raw material for preparing 2-ethylhexyl acrylate.

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