CN114621081A

CN114621081A - Method for preparing acrylic acid by using acrylate waste

Info

Publication number: CN114621081A
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: 2022-06-14
Anticipated expiration: 2042-02-22
Also published as: CN114621081B

Abstract

The invention discloses a method for preparing acrylic acid by using acrylate waste. The raw material acrylate waste material is mainly a byproduct or residual monomer which is not completely reacted for producing polyester, acrylate, amino acid and acrylamide products. The method mainly comprises the following steps: after the acrylate waste is dissolved by adding water, filtering out particles and flocculent undissolved substances in the acrylate waste, and reacting the acrylate waste 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 bond action of water and acrylic acid and improve the relative volatility of the water and the acrylic acid; and the separated process water and the hydrophilic agent are all recycled as the solvent for recycling. The acrylic acid produced by the process can meet all acrylic acid application scenes. 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 using acrylate waste

Technical Field

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

Background

In some domestic chemical plants for producing polyester, various acrylate, amino acid and acrylamide products, the production process is accompanied by byproducts of which the main components are acrylic acid or acrylate, according to incomplete statistics, the yield of the byproducts is dozens of ten thousand tons every year, the byproducts contain various impurities, the utilization value is extremely low, soil water sources and the like are polluted and cannot be discarded at will, and burden is brought to production enterprises. Acrylic acid plays a very important role in the field of fine chemicals, and polymers prepared from the acrylic acid are widely applied to the fields of dispersing agents, flocculating agents, thickening agents, detergents, synthetic rubber emulsions, super absorbent resins and the like. Acrylic fibers are also widely used in the manufacture of textiles such as garments, decorative articles, artificial fur and the like. The application is very wide, and the price per ton is between one thousand yuan and several ten thousand yuan.

The production method of acrylic acid mainly comprises acrylonitrile hydrolysis method, propylene two-step oxidation method, cyanoethanol method, propiolactone method and the like, or improvement technologies of the methods.

The recent applications for acrylic acid production methods, mainly patent applications with application numbers CN201810674921.4 and CN201710628197.7, relate to acrylic acid production methods, mainly solving the problems of low conversion rate of acrolein and low yield of acrylic acid of the existing catalysts, including that acrolein is reacted with an oxygen-containing oxidizing gas in the presence of a catalyst to obtain acrylic acid, wherein the catalyst includes a carrier and an active component supported on the carrier, the active component is represented by the general formula: VMoaTibWcXdYeZfOg, wherein X is selected from one or more of Sc, Y, Zr, Hf, Ta and Cr, Y is selected from at least one of Ga, Ge, In, Sn, TI, Pb, Cd, Mn, Tc, Re, Rh, Ir, Pd, Pt, Ag, Au and La, and Z is selected from one or more of alkali metals or alkaline earth metals, thereby better solving the technical problem and being applicable to the industrial production of acrylic acid; the invention application of application No. CN201780031814.3 provides a process for the production of a monomer, such as acrylic acid, wherein the process comprises oxidizing one or more reaction gases, such as propylene, in a fixed bed reactor, preferably two fixed bed reactors, in the presence of oxygen and a mixed metal oxide catalyst to form an oxidized gaseous mixture, and at any point in the oxidation, feeding or flowing the one or more reaction gases or the oxidized gaseous mixture 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 98 wt% of the total pore volume in the inert macroporous material has a pore diameter of at least 100 μ ι η; the invention application of application No. CN200480000580.9 aims to provide a process for producing (meth) acrolein or (meth) acrylic acid by gas phase catalytic oxidation, which can smoothly accomplish temperature control of a heat medium, can effectively prevent hot spots and is easy to handle; the invention of application No. CN200480000550.8 is directed to providing an apparatus for producing (meth) acrolein or (meth) acrylic acid by performing a gas phase catalytic oxidation reaction of propane, propylene, isobutylene or (meth) acrolein in an oxygen-containing gas using an inorganic salt as a heat medium for reaction temperature adjustment, wherein a body of an adjusting valve provided in a heat medium feeder for controlling the supply and circulation rate of the heat medium and a material of a gland member mounted on the body for sliding sealing are mica-based materials. 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 stably produced in high yield for a long time without deteriorating the performance of a catalyst by coking or the like of the catalyst and the following troubles such as increase in pressure difference and clogging of a reaction tube even when air containing a large amount of suspended particles is used as an oxygen source; the invention application with application number 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 the oxygen source. A process for producing acrylic acid by the steps of catalytic gas phase oxidation, absorbing acrylic acid with an absorbent, and dehydrating an acrylic acid-containing aqueous solution, 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 be in the range of 0.06 to 0.8 wt.%, thereby substantially preventing the bottom of the azeotropic dehydration column from containing an azeotropic solution and water. As a result, the production of polymer 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 technique has been found for producing acrylic acid from acrylate waste. The existing technology for separating acrylic acid and water adopts multi-tower extractive distillation or azeotropic distillation, water and acrylic acid can be efficiently separated by adding an extracting agent or an entrainer which is insoluble in water, but the extracting agent or the entrainer and water form a new mixture, the extracting agent and the entrainer which are purer need to be separated and recovered can be reused, the extracting agent and the entrainer can not be completely recovered, the organic solvent which can not be recovered can cause pollution, the separation or recovery 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 acrylate waste materials, in order to prepare high-purity acrylic acid, a hydrophilic agent dissolved in water is adopted, the strong hydrogen bond action of the acrylic acid and the water can be destroyed, the relative volatility of the acrylic acid and the water is improved, the separation of the acrylic acid and the water is easy, the acrylic acid and the water can be relatively and thoroughly separated by using a single tower, and the distilled hydrophilic agent and the distilled water can be completely recycled as a solvent of the acrylate waste materials after being condensed or can be completely recycled for diluting concentrated sulfuric acid without being separated from water. Therefore, the hydrophilic agent is completely recycled, zero emission is realized, the environment is not polluted, and extra cost is not increased.

The technical scheme is as follows: a method for preparing acrylic acid by utilizing acrylate waste is characterized by comprising the following steps: 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 acrylate waste material is a mixture which takes some acrylates generated in chemical production as main components, and contains most of the acrylates, and also contains all or one or more of formate, acetate, citrate, carbonate, chloride, polyacrylate, oligosaccharide and the like.

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

The hydrophilic agent refers to strong hydrophilic substances such as ethanol, n-propanol, n-butanol, isobutanol, tert-butanol, n-pentanol, isoamylol, formic acid, propionic acid and the like.

The polymerization inhibitor refers to all chemicals or articles which can prevent acrylic acid from polymerizing, such as phenols, quinones, ethers and the like.

A method for preparing acrylic acid by using acrylate waste comprises the following steps:

1. filtration and crude purification of acrylate waste

Adding a certain amount of water into a batching tank, adding the acrylate waste while stirring, after the dissolution is finished, carrying out vacuum filtration by using a filter medium, and filtering to obtain a uniform aqueous solution a.

2. Dilution with acid

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

3. Reaction of

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

4. Distillation crystallization

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

5. Refining by rectification

And (3) in order to obtain high-purity acrylic acid, pumping the acrylic acid aqueous solution d prepared in the step (4) into an evaporation kettle of an intermittent or continuous rectifying tower, adding a certain amount of polymerization inhibitor, hydrophilic agent and boiling stabilizer, and carrying out vacuum distillation. The hydrophilic agent can destroy the strong hydrogen bond action of the acrylic acid and the 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 column should have 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 bottom is 4-21kPa, and the temperature of the tower bottom is 50-70 ℃. The tower kettle is heated by hot water, heat transfer oil or low-pressure steam. Adding a proper amount of hydrophilic agent, and separating water and acrylic acid by controlling the extracted amount at the top of the tower. Water and a hydrophilic agent solution e are obtained at the tower top, and more than 99 percent of acrylic acid is obtained at the tower bottom.

6. Water reuse

The solution e obtained in the step 5 is directly used as a solvent of the waste for recycling, so that the generation of sewage is reduced, the separation process of an extracting agent and an entrainer in conventional extractive distillation and azeotropic distillation is avoided, the process complexity is reduced, and the energy consumption is reduced.

The acrylic acid product prepared by the method 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, less investment and low operation cost, the production cost per ton is less than thousand yuan, the value of the prepared product is from ten thousand yuan per ton to several ten thousand yuan per ton, and the invention is a good method for changing waste into valuable.

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

1. the pollution problem of the acrylate waste is solved.

2. Preparing high-value acrylic acid products with wide application.

3. The problem of acrylic acid self-polymerization in the preparation process is prevented by using an auxiliary agent such as a polymerization inhibitor.

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

5. The vacuum distillation is adopted to reduce the energy consumption.

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

7. The process water is completely recycled, and environmental pollution is avoided.

Drawings

FIG. 1 is a process flow diagram of a method for preparing acrylic acid from acrylate waste.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.

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. As used herein, the term "and/or" 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 from acrylate waste, comprising the following steps:

s101, dissolving acrylate waste materials by using a certain amount of water in a dosing tank, and then performing coarse purification on the aqueous solution in a filtering mode.

S102, the water solution after coarse purification in the step S101 enters an evaporation tank, and then strong acid with a certain concentration is added to react with the acrylate waste material to prepare acrylic acid and a strong acid salt water solution.

S103, adding a boiling stabilizer and a polymerization inhibitor into the acrylic acid and the strong acid salt aqueous solution prepared in the step S102, and simply distilling in an evaporating pot to realize solid-liquid separation. The gas phase is condensed to obtain a relatively pure acrylic acid aqueous solution.

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

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

Example 1

The components of the acrylate waste material for the experiment are about 80 percent of sodium acrylate, about 10 percent of sodium polyacrylate, about 2 percent of oligosaccharide, and a small amount of sodium citrate, sodium acetate, sodium formate, sodium carbonate, calcium chloride and the like. Sending 240 parts of sodium acrylate waste material into a batching tank by wind, adding 200 parts of water, uniformly stirring, pumping into a filter column by a pump for suction filtration, feeding clear liquid into a reaction tank, adding 200 parts of 50% sulfuric acid aqueous solution while stirring, adding 0.003 part of polymerization inhibitor after the reaction is finished, adding 0.1 part of zeolite and 0.001 part of boiling stabilizer, uniformly mixing, feeding into an evaporator I, keeping an air inlet of the evaporator I open, setting the temperature to be 80 ℃, carrying out vacuum distillation, condensing steam to obtain 32% acrylic acid aqueous solution, feeding into a crude product storage tank, and obtaining crystals with the main component of sodium sulfate at the bottom of the tower, wherein the crystals are loose and convenient to discharge. Then 40% acrylic acid aqueous solution is added into a rectifying tower II, 2000 parts of isopropanol is added as a hydrophilic agent, the pressure at the top of the tower is set to be 5kPa, the temperature at the top of the tower is 25 ℃, the temperature at the bottom of the tower is 7kPa, the temperature at the bottom of the tower is 50 ℃, and the reflux ratio is controlled to be 2. Water and isopropanol are obtained at the tower top, and high-purity acrylic acid is obtained at the tower bottom. Water and isopropanol are recycled as solvents.

Example 2

The conditions were the same as in example 1, the overhead pressure was 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 hydrophilic agent was changed to n-propanol, the overhead pressure was set to 5kPa, the overhead temperature was 21 ℃, the column bottom was 7kPa, the column bottom temperature was 50 ℃, and the reflux ratio was controlled to 2.

Example 4

The conditions were the same as in example 3, the column top pressure was 10kPa, the column top temperature was 32 ℃, the column bottom temperature was 12kPa, and the column 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 hydrophilic agent was changed to ethanol, the overhead pressure was 5kPa, the overhead temperature was 17 ℃, the column bottom was 7kPa, the column bottom temperature was 52 ℃, and the reflux ratio was controlled to 2.

Example 6

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

In 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 an appropriate extraction ratio according to the composition of the raw materials.

Comparative example 1

The procedure of example 1 was followed except that no boiling stabilizer was added, and the other steps were the same. The evaporator I is subjected to explosive boiling, sodium sulfate solid is attached to the coil pipe, the wall adhesion is serious, the heat transfer is influenced, the evaporation rate is reduced, and the discharging is difficult.

Comparative example 2

Only zeolite and no boiling stabilizer are added in the step of the example 1, and other steps are the same. The evaporator I has large bubbles, a small amount of sodium sulfate solid is attached to the coil pipe, the heat transfer is influenced, the evaporation rate is reduced, and the discharging is difficult.

Comparative example 3

The procedure of example 1 is carried out without adding zeolite, with boiling stabilizer, and the other steps are the same. The evaporator I has slight bumping, and a small amount of sodium sulfate solid is attached to the coil pipe, so that the heat transfer is influenced, the evaporation rate is reduced, and the discharging is difficult.

Comparative example 4

The same procedure as in example 1 above was followed except that the evaporator inlet was closed. The aqueous acrylic acid solution obtained by condensation was found to be slippery, sticky and self-polymerized.

Comparative example 5

The procedure of example 1 was repeated except that no hydrophilic agent was added, and the other steps were the same. It was found that water was distilled off together with acrylic acid, and the bottom fraction was hardly distilled off, whereby acrylic acid of high purity was not obtained, and the recovery rate of acrylic acid was also greatly reduced.

Claims

1. A method for preparing acrylic acid by utilizing acrylate waste is characterized by comprising the following steps: the weight percentage 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.

2. The acrylate scrap as claimed in claim 1 means by-products or unreacted residual monomers from the production of polyesters, acrylic esters of various types, amino acids, acrylamides; or the acrylate mixture obtained by neutralizing the byproducts or residual monomer acrylic acid generated in the production of polyester, various acrylate, amino acid and acrylamide products; the waste also contains one or more of formate, acetate, citrate, carbonate, chloride, polyacrylate, oligosaccharide, etc.

3. The hydrophilic agent of claim 1 is a strongly hydrophilic substance such as ethanol, n-propanol, n-butanol, isobutanol, t-butanol, n-pentanol, isopentanol, formic acid, propionic acid, etc.

4. The strong acid according to claim 1 is an organic or inorganic acid having a higher strength than acrylic acid, such as sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, etc.

5. The polymerization inhibitor according to claim 1 is a chemical or an article which can inhibit polymerization of acrylic acid, such as phenols, quinones, ethers, etc.;

the evaporated acrylic acid steam and the condensed acrylic acid solution lose the inhibition effect of oxygen in a vacuum state and easily generate self-polymerization, so a small air inlet is reserved on the evaporator in the method, and air is continuously introduced to play a role in inhibiting polymerization.

6. The boiling stabilizer as claimed in claim 1 is a chemical or article which can prevent the system from bumping, such as certain polysiloxane compounds (silicone oil, silicone ring, silicone rubber, silicone resin, etc.) or silicon bentonite, zeolite, broken ceramic chips, glass beads, etc.

7. A method for preparing acrylic acid by using acrylate waste comprises the following steps:

the method comprises the following steps: filtration and crude purification of acrylate waste

Dissolving the acrylate mixture in water in a dissolving tank, and then filtering to obtain a water solution with uniform composition;

step two: acid making reaction

And (3) slowly adding the aqueous solution prepared in the step one into a certain amount of strong acid aqueous solution with a certain concentration to prepare the acrylic acid aqueous solution. Controlling the reaction temperature to be not more than 60 ℃;

step three: distillation crystallization

Adding a certain amount of polymerization inhibitor and boiling stabilizer into the acrylic acid aqueous solution prepared in the step two, pumping the acrylic acid aqueous solution into a distillation kettle or a vacuum crystallizer, carrying out vacuum distillation or crystallization, and separating sulfate to obtain a dilute acrylic acid solution;

step four: rectification

Adding a certain amount of polymerization inhibitor and hydrophilic agent into the acrylic acid aqueous solution prepared in the step three, feeding the acrylic acid aqueous solution into an intermittent or continuous rectifying tower, and separating water and acrylic acid to obtain a high-purity acrylic acid product; 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 ℃; according to the composition of the acrylic acid aqueous solution, a proper amount of hydrophilic agent is added, and water and acrylic acid are separated by controlling the produced amount at the top of the tower.

8. The evaporation device used in the step 7 comprises batch distillation equipment such as a distillation still and a tank and similar continuous distillation equipment such as a rectifying tower, a scraper evaporator, a membrane concentrator, a short-path evaporator and a molecular evaporator.