CN114621081B

CN114621081B - Method for preparing acrylic acid by utilizing acrylate waste

Info

Publication number: CN114621081B
Application number: CN202210160177.2A
Authority: CN
Inventors: 翟乃华
Original assignee: Qingdao Agricultural University
Current assignee: Qingdao Agricultural University
Priority date: 2022-02-22
Filing date: 2022-02-22
Publication date: 2023-08-22
Anticipated expiration: 2042-02-22
Also published as: CN114621081A

Abstract

The invention discloses a method for preparing acrylic acid by utilizing acrylate waste. The source of the raw material acrylic acid salt waste is mainly byproducts or residual monomers which do not react completely in the production of polyester products, acrylic esters, amino acids and acrylamide products. The method mainly comprises the following steps: adding water into the acrylate waste material to dissolve, filtering out particles and flocculent insoluble matters in the acrylate waste material, and reacting the acrylate waste material with strong acid to obtain an acrylic acid dilute solution; adding an auxiliary agent, and distilling and rectifying to obtain the high-purity acrylic acid. The added hydrophilic agent can destroy the strong hydrogen bonding effect of water and acrylic acid, and improves the relative volatility of the water and the acrylic acid; the separated process water and hydrophilic agent are all recovered and used as solvent for recycling. The acrylic acid produced by the process can meet all application scenes of the acrylic acid. The method avoids the common multi-tower azeotropic distillation and extractive distillation processes for separating water and acrylic acid systems, has simple production process, less pollutants and low cost, is a good method for changing waste into valuable, and has great value.

Description

Method for preparing acrylic acid by utilizing acrylate waste

Technical Field

The invention belongs to the fields of chemical technology and environmental protection, in particular relates to a method for preparing acrylic acid, and discloses a method for preparing acrylic acid by utilizing acrylate waste.

Background

Some domestic chemical plants for producing polyester, various acrylic ester, amino acid and acrylamide products are accompanied by byproducts of acrylic acid or acrylic acid salt as main components in the production process, and according to incomplete statistics, the byproducts are produced in hundreds of thousands of tons each year, and because the byproducts contain various impurities, the utilization value is extremely low, the byproducts pollute soil water sources and the like, cannot be discarded at will, and bring burden to production enterprises. Acrylic acid plays a very important role in the field of fine engineering, and polymers prepared from acrylic acid are widely used in the fields of dispersants, flocculants, thickeners, washing aids, synthetic rubber emulsions, super absorbent resins and the like. Acrylic fibers are also widely used in the processing of textiles such as apparel, ornamental articles, manmade fur, and the like. The use is very wide, and the price per ton is between ten thousand yuan and tens of thousands yuan.

The production method of acrylic acid mainly includes the processes of acrylonitrile hydrolysis method, propylene two-step oxidation method, cyanoethanol method and propiolactone method, etc. or the improved techniques of these several processes.

In recent years, the application of the production method of the acrylic acid mainly comprises application numbers of CN201810674921.4 and CN201710628197.7, and relates to the production method of the acrylic acid, which mainly solves the problems of low acrolein conversion rate and low acrylic acid yield of the existing catalyst, and comprises the steps of reacting acrolein with oxygen-containing oxidizing gas in the presence of the catalyst to obtain the acrylic acid, wherein the catalyst comprises a carrier and an active component supported on the carrier, and the general formula of the active component is expressed as follows: the technical scheme of VMoaTibWcXdYeZfOg, wherein X is one or more selected from Sc, Y, zr, hf, ta, cr, Y is at least one selected from Ga, ge, in, sn, TI, pb, cd, mn, tc, re, rh, ir, pd, pt, ag, au, la, and Z is one or more selected from alkali metal or alkaline earth metal, so that the technical problem is better solved, and the method can be used in the industrial production of acrylic acid; the invention application of application number CN201780031814.3 provides a process for the production of monomers such as acrylic acid, wherein the process comprises oxidizing one or more reactive gases, e.g. propylene, in the presence of oxygen and a mixed metal oxide catalyst in a fixed bed reactor, preferably two fixed bed reactors, to form an oxidized gaseous mixture, and at any point in the oxidation, feeding or flowing the one or more reactive gases or the oxidized gaseous mixture through or through an inert macroporous material having a pore volume of 0.2cm3/g to 2.0cm3/g, a surface area of 0.01 to 0.6m2/g, and wherein 30 to 98wt% of the total pore volume in the inert macroporous material has a pore size of at least 100 μm; the invention of application number CN200480000580.9 is aimed at providing a process for producing (meth) acrolein or (meth) acrylic acid by gas-phase catalytic oxidation reaction, which can smoothly accomplish temperature control of a heat medium, can effectively prevent hot spots and is easy to handle; the invention of CN200480000550.8 is to provide a device for producing (meth) acrolein or (meth) acrylic acid by performing a catalytic gas-phase oxidation reaction of propane, propylene, isobutylene or (meth) acrolein under an oxygen-containing gas using an inorganic salt as a heat medium for regulating a reaction temperature, characterized in that a material of a gland member provided on a heat medium feeder for controlling a main body of a heat medium supply and circulation rate regulating valve and a rotary shaft mounted on the main body for sliding sealing is a mica-based material. An object of the present invention is to provide a process for producing acrolein and/or acrylic acid by which acrolein and/or acrylic acid can be produced stably in high yield for a long period of time without deteriorating the performance of a catalyst due to coking or the like of the catalyst even when air containing a large amount of suspended particles is used as an oxygen source, and with such troubles as an increase in pressure difference and clogging of a reaction tube; the invention application CN01116867.6 relates to a process for producing acrolein and/or acrylic acid by gas phase oxidation of propylene and propane with an oxygen-containing gas in the presence of an oxidation catalyst, wherein air from which suspended particles are removed is used as an oxygen source. A process for producing acrylic acid by a step of catalyzing a gas phase oxidation reaction, absorbing acrylic acid with an absorbent, and dehydrating an aqueous solution containing acrylic acid, characterized in that the dehydration step comprises adding an azeotropic solvent, distilling the resultant mixture, and adjusting the degree of acrylic acid at the top of the column to a range of 0.06 to 0.8wt.%, thereby substantially preventing the azeotropic dehydration column bottom from containing an azeotropic solution and water. As a result, the production of acrylic acid in any distillation column involved in the production is avoided, and the effective utilization of acrylic acid is achieved.

From the above analysis, no technology related to the production of acrylic acid from acrylic acid salt waste has been found. The existing technology for separating acrylic acid and water adopts multi-tower extraction rectification or azeotropic rectification, water and acrylic acid can be efficiently separated by adding an extracting agent or an entrainer which is insoluble in water, however, the extracting agent or the entrainer and water form a new mixture, the purer extracting agent and the entrainer can be recycled by separation, the extracting agent and the entrainer can not be completely recycled, the organic solvent which can not be recycled can cause pollution, the separation or recycling process is complex, multi-tower operation is needed, and the production cost is high.

Disclosure of Invention

In order to overcome the problems, the invention provides a method for producing acrylic acid by using acrylic acid salt waste, which adopts a hydrophilic agent dissolved in water to prepare high-purity acrylic acid, so that the strong hydrogen bonding effect of the acrylic acid and the water can be destroyed, the relative volatility of the acrylic acid and the water can be improved, the acrylic acid and the water can be easily separated by utilizing a single tower, meanwhile, the distilled hydrophilic agent and water can be completely recycled as a solvent of the acrylic acid salt waste or completely recycled and then used for diluting concentrated sulfuric acid, and water separation is not needed. Therefore, the hydrophilic agent is fully recycled, zero emission is realized, the environment is not polluted, and the additional cost is not increased.

The technical scheme is as follows: a method for preparing acrylic acid by utilizing acrylate waste is characterized in that: the weight fraction of the raw materials is as follows: 100 parts of acrylate waste, 10-100 parts of water, 10-2000 parts of hydrophilic agent, 10-100 parts of acid, 0.01-10 parts of boiling stabilizer and 0.00001-10 parts of polymerization inhibitor.

The said acrylic acid salt waste material is the mixture with some acrylic acid salt as main component, which contains most acrylic acid salt, and one or several kinds of formate, acetate, citrate, carbonate, chloride, polyacrylate, oligosaccharide and other components.

The acid refers to organic acid or inorganic acid with higher intensity than acrylic acid, such as sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid and the like.

The hydrophilic agent is ethanol, n-propanol, n-butanol, isobutanol, tertiary butanol, n-amyl alcohol, isoamyl alcohol, formic acid, propionic acid and other strong hydrophilic substances.

The polymerization inhibitor refers to chemicals or articles of phenols, quinones and ethers which can prevent acrylic acid from polymerizing.

A method for preparing acrylic acid by utilizing acrylate waste, comprising the following steps:

1. filtration crude purification of acrylate waste

Adding a certain amount of water into a batching tank, adding the acrylate waste while stirring, and filtering after dissolution is completed to obtain an aqueous solution a with uniform composition.

2. Acid dilution

Adding a certain amount of water into a reaction tank, slowly adding a certain amount of acid while stirring, and preparing an acid solution b with a certain concentration.

3. Reaction

Slowly adding the solution a prepared in the step 1 into the acid solution b prepared in the step 2, and reacting to generate acrylic acid and sulfate water solution c.

4. Distillation crystallization

Adding the acrylic acid and the sulfate aqueous solution c prepared in the step 3 into a polymerization inhibitor and a boiling stabilizer, stirring uniformly, continuously pumping into an evaporator or a crystallizer at a certain flow, vacuum distilling or crystallizing, controlling the operation temperature to be 30-60 ℃, and steaming out the acrylic acid aqueous solution d to obtain sulfate at the bottom of the tank.

5. Rectifying and refining

In order to obtain the high-purity acrylic acid, the acrylic acid aqueous solution d prepared in the step 4 is pumped into an evaporation kettle of a batch or continuous rectifying tower, and then a certain amount of polymerization inhibitor, hydrophilic agent and boiling stabilizer are added for vacuum distillation. The hydrophilic agent can destroy the extremely strong hydrogen bonding action of the acrylic acid and water, and increase the relative volatility of the acrylic acid and the water so as to improve the purity and the recovery rate of the acrylic acid.

The rectifying tower has a separation capacity of not less than 5 theoretical plates. The pressure at the top of the tower is 3-20kPa, and the temperature is 40-60 ℃; the pressure of the tower kettle is 4-21kPa, and the temperature of the tower kettle is 50-70 ℃. The tower bottom is heated by hot water, heat conducting oil or low-pressure steam. Adding proper amount of hydrophilic agent, and separating water and acrylic acid by controlling the extraction amount at the top of the tower. Water and hydrophilic agent solution e are obtained at the top of the tower, and acrylic acid with the concentration of more than 99% is obtained at the bottom of the tower.

6. Water reuse

The solution e obtained in the step 5 is directly used as a solvent of waste materials for recycling so as to reduce the generation of sewage, avoid the separation process of an extractant and an entrainer in conventional extractive distillation and azeotropic distillation, reduce the complexity of the process and reduce the energy consumption.

The method for preparing the acrylic acid by utilizing the acrylic acid salt waste material can be widely applied to the fields of synthetic rubber emulsion manufacture, dispersing agents, flocculating agents, thickening agents, washing aids, super absorbent resins and the like.

The invention has simple production process, low investment and low operation cost, the production cost per ton is less than thousand yuan, and the value of the prepared product is tens of thousands yuan per ton to tens of thousands yuan, thus being a good method for changing waste into valuable.

By combining the scheme, the method for preparing the acrylic acid by utilizing the acrylate waste has the following beneficial effects:

1. solves the pollution problem of the acrylate waste.

2. A high value acrylic acid product with wide application is prepared.

3. The use of polymerization inhibitors and other auxiliary agents prevents the problem of acrylic acid self-polymerization in the preparation process.

4. The practical special equipment realizes solid-liquid continuous separation and continuous production.

5. The vacuum distillation reduces the energy consumption.

6. Hydrophilic agent is added to efficiently separate water and acrylic acid, so that separation energy consumption is reduced, acrylic acid purity is improved, and acrylic acid loss is reduced.

7. The process water is recycled completely, thus avoiding environmental pollution.

Drawings

FIG. 1 is a process flow diagram of a method for producing acrylic acid from acrylic acid salt waste.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit or scope of the invention, which is therefore not limited to the specific embodiments disclosed below.

All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

As shown in fig. 1, the present invention provides a method for preparing acrylic acid by using an acrylate waste material, comprising the following steps:

s101, dissolving the acrylate waste material with a certain amount of water in a batching tank, and then coarsely purifying the water solution by adopting a filtering mode.

And S102, feeding the aqueous solution after the crude purification in the step S101 into an evaporation tank, and then adding strong acid with a certain concentration to react with acrylate waste to prepare acrylic acid and strong acid salt aqueous solution.

And S103, adding the boiling stabilizer and the polymerization inhibitor into the aqueous solution of the acrylic acid and the strong acid salt prepared in the step S102, and simply distilling in an evaporation tank to realize solid-liquid separation. The relatively pure aqueous acrylic acid solution is obtained after gas phase condensation.

And S104, adding a polymerization inhibitor and a hydrophilic agent into the acrylic acid aqueous solution prepared in the step S103, and then, feeding the aqueous solution into a rectifying tower to rectify and separate water and acrylic acid. The overhead water and hydrophilic agent are condensed and then all recovered as a solvent for the acrylate salt or as a diluent for the strong acid. High-purity acrylic acid is obtained at the bottom of the column.

The technical scheme of the present invention will be further described with reference to examples, which should not be construed as limiting the technical scheme.

Example 1

The components of the acrylate waste used in the experiment are about 80% of sodium acrylate, about 10% of sodium polyacrylate, about 2% of oligosaccharide, and a small amount of sodium citrate, sodium acetate, sodium formate, sodium carbonate, calcium chloride and the like. 240 parts of sodium acrylate waste is sent into a batching tank by wind, 200 parts of water is added, the mixture is stirred uniformly, pumped into a filtering column by a pump for suction filtration, clear liquid enters a reaction tank, 200 parts of 50% sulfuric acid aqueous solution is added while stirring, 0.003 part of polymerization inhibitor is added after the reaction is finished, 0.1 part of zeolite and 0.001 part of boiling stabilizer are added, the mixture is uniformly mixed and enters an evaporator I, a reserved air inlet of the evaporator I is opened, the temperature is set to 80 ℃, the vacuum distillation is carried out, 32% acrylic acid aqueous solution is obtained after steam condensation, the obtained product enters a crude product storage tank, and crystals with the main components of sodium sulfate are obtained at the bottom of the tower, and the product is loose and convenient to discharge. Then adding 40% acrylic acid aqueous solution into a rectifying tower II, adding 2000 parts of isopropanol as a hydrophilic agent, setting the tower top pressure to be 5kPa, the tower top temperature to be 25 ℃, and the tower bottom temperature to be 7kPa, and controlling the reflux ratio to be 2. Water and isopropanol are obtained at the top of the tower, and high-purity acrylic acid is obtained at the bottom of the tower. The water and the isopropanol are used as solvents for recycling.

Example 2

The conditions were the same as in example 1, the overhead pressure was controlled to 10kPa, the overhead temperature was 32 ℃, the column bottom temperature was 12kPa, the column bottom temperature was 64 ℃, and the reflux ratio was 2.

Example 3

The conditions were the same as in example 1, except that the hydrophilizing agent was changed to n-propanol, the pressure at the top of the column was 5kPa, the temperature at the top of the column was 21 ℃, the temperature at the bottom of the column was 7kPa, the temperature at the bottom of the column was 50℃and the reflux ratio was controlled to 2.

Example 4

The conditions were the same as in example 3, the overhead pressure was set at 10kPa, the overhead temperature was 32 ℃, the bottom temperature was 12kPa, the bottom temperature was 63 ℃, and the reflux ratio was controlled to 2.

Example 5

The conditions were the same as in example 1, except that the hydrophilizing agent was changed to ethanol, the pressure at the top of the column was 5kPa, the temperature at the top of the column was 17 ℃, the temperature at the bottom of the column was 7kPa, the temperature at the bottom of the column was 52 ℃, and the reflux ratio was controlled to 2.

Example 6

The conditions were the same as in example 5, the overhead pressure was set at 10kPa, the overhead temperature was 29 ℃, the column bottom temperature was 12kPa, the column bottom temperature was 64 ℃, and the reflux ratio was controlled at 2.

According to the above examples 1 to 6, acrylic acid products having a purity and a recovery rate of 99% or more can be obtained in the column bottom by using a proper extraction ratio depending on the composition of the raw materials.

Comparative example 1

The procedure of example 1 above was followed except that no boiling stabilizer was added, and the procedure was the same. The evaporator I is boiled, sodium sulfate solid is adhered to the coil pipe, the wall adhesion is serious, the heat transfer is affected, the evaporation rate is reduced, and the discharging is difficult.

Comparative example 2

The procedure of example 1 above was followed by the addition of zeolite alone, without boiling stabilizer, and the other steps were the same. The evaporator I has large bubbles, a small amount of sodium sulfate solid is attached to the coil, heat transfer is affected, evaporation rate is reduced, and discharging is difficult.

Comparative example 3

The procedure of example 1 above was carried out without the addition of zeolite, with the addition of boiling stabilizer, and with the same procedure. The evaporator I has slight bumping, a small amount of sodium sulfate solid is attached to the coil pipe, heat transfer is affected, evaporation rate is reduced, and discharging is difficult.

Comparative example 4

The procedure of example 1 above is the same except that the evaporator inlet is closed. The aqueous acrylic acid solution obtained by condensation was found to be slippery and tacky, and had a self-polymerization phenomenon.

Comparative example 5

The procedure of example 1 above was followed except that no hydrophilic agent was added, and the procedure was otherwise the same. It was found that water was distilled out with acrylic acid, water at the bottom of the column was hardly distilled out, acrylic acid of high purity was not obtained, and the recovery rate of acrylic acid was also greatly lowered.

Claims

1. A method for preparing acrylic acid by utilizing acrylate waste is characterized in that: the weight fraction of the raw materials is as follows: 100 parts of acrylate mixture, 10-100 parts of water, 10-2000 parts of hydrophilic agent, 10-100 parts of strong acid, 0.01-10 parts of boiling stabilizer and 0.00001-10 parts of polymerization inhibitor;

the method comprises the following specific steps:

step one: filtration crude purification of acrylate waste

The acrylic acid salt waste material is selected from various acrylic acid esters, byproducts of acrylamide products or residual monomers which do not react, and the acrylic acid salt mixture is dissolved by water in a dissolving tank and then filtered to obtain an aqueous solution with uniform composition;

step two: acid production reaction

Slowly adding quantitative strong acid aqueous solution with certain concentration into the aqueous solution prepared in the step one, wherein the strong acid is sulfuric acid to prepare acrylic acid aqueous solution, and controlling the reaction temperature to be not more than 60 ℃;

step three: distillation crystallization

Adding quantitative polymerization inhibitor and boiling stabilizer into the acrylic acid aqueous solution prepared in the second step, pumping into a distillation kettle or a vacuum crystallizer, vacuum distilling or crystallizing, and separating sulfate to obtain dilute acrylic acid solution;

step four: rectifying

Adding a quantitative polymerization inhibitor and a hydrophilic agent into the dilute solution of the acrylic acid prepared in the step three, and feeding the dilute solution into an intermittent or continuous rectifying tower to separate water and the acrylic acid, thereby obtaining an acrylic acid product with high purity; the separated hydrophilic agent and water are used as solvents for dissolving raw materials for recycling;

the pressure at the top of the rectifying tower is 3-20kPa, and the temperature at the top of the rectifying tower is 40-60 ℃; the pressure of the tower kettle is 4-21kPa, and the temperature of the tower kettle is 50-70 ℃.

2. The method for preparing acrylic acid by using the waste acrylic acid salt according to claim 1, wherein: the hydrophilic agent adopts isopropanol or n-propanol.

3. The method for preparing acrylic acid by using the waste acrylic acid salt according to claim 1, wherein: the polymerization inhibitor is phenol, quinone or ether chemical.

4. The method for preparing acrylic acid by using the waste acrylic acid salt according to claim 1, wherein: the boiling stabilizer is one of silicone oil, organic silicon ring, silicone rubber, silicone resin, bentonite, zeolite, broken ceramic chip and glass bead.