Method for catalytically synthesizing acrylic ester from acrylic acid and low-level monohydric alcohol

Abstract

The invention provides a method for catalytically synthesizing acrylic ester from acrylic acid and low-level monohydric alcohol, and relates to the technical field of acrylic ester preparation. The method for catalytically synthesizing the acrylic ester mainly comprises the following steps: by taking acrylic acid and a low-level monohydric alcohol mixed polymerization inhibitor as raw materials and strongly acidic cationic resin D72 as a catalyst, carrying out reactive distillation in a reactive distillation tower, then separating and dehydrating by adopting a molecular sieve membrane, and then preparing the high-purity acrylic ester through a light component removal tower and a purification tower. The defects in the prior art are overcome, the production efficiency of the acrylate can be effectively improved, and meanwhile, the energy consumption and the production cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of acrylate preparation, and in particular to a method for catalytically synthesizing acrylate from acrylic acid and lower monohydric alcohol. Background Art

[0002] Acrylate is an important synthetic intermediate and a monomer for synthetic polymers. It is widely used in the rubber, pharmaceutical, leather, papermaking, adhesives and coatings industries.

[0003] Existing acrylic acid production methods, such as U.S. Patent Application Publication No. 2004 / 0236143, disclose a method for preparing (meth) acrylic acid ester by reacting (meth) acrylic acid (which may be crude (meth) acrylic acid) with alcohol in the presence of at least one acid catalyst. In the method, the reaction temperature is above 120°C. When the reaction temperature is high, acrylic acid generates more high-boiling products. Concentrated sulfuric acid is used as a catalyst, which causes serious equipment corrosion. The mixture after esterification needs to be washed with a large amount of water. After washing, an alcohol recovery tower is required to recover the alcohol, which results in high energy consumption. The preparation method of methyl acrylate and butyl acrylate proposed in Japanese Patent CN1291606A has a reaction temperature of 60-80°C, and the molar ratio of acrylic acid to alcohol is twice that of alcohol. Not only a large amount of water is required for washing, but also distillation is required to recover acrylic acid, which results in high energy consumption. That is, the production of acrylic acid ester in the existing method has problems such as low efficiency, large amount of washing liquid and high energy consumption. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for catalytically synthesizing acrylic esters from acrylic acid and low-level monohydric alcohols, which can effectively improve the production efficiency of acrylic esters while reducing energy consumption and production costs.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented through the following technical solutions:

[0006] A method for catalytically synthesizing acrylic acid esters from acrylic acid and lower monohydric alcohols, the method comprising the following steps:

[0007] S1. The reaction raw materials are arranged in the following proportions: the molar ratio of acrylic acid to lower monohydric alcohol is 1:1.1-1.5, and the polymerization inhibitor accounts for 0.05-0.1% by weight of the total reaction raw materials;

[0008] S2, adding the above reaction raw materials into a reaction distillation tower filled with strong acid cationic resin D72 for reaction distillation, the steam distilled from the top of the tower enters a molecular sieve membrane separation device for dehydration, and the bottom material is transported to an acrylic acid recombination and splitting tower for recovery;

[0009] S3, condensing the dehydrated mixture and adding a polymerization inhibitor, a part of which enters the top of the reactive distillation tower as reflux liquid, and the other part is transported to the light removal tower for treatment;

[0010] S4, the distillate removed from the top of the light removal tower is transported back to the reactive distillation tower, and the bottom material is transported to the purification tower for purification, wherein the distillate from the top of the purification tower is high-purity acrylate, and the bottom material is returned to the reactive distillation tower.

[0011] Preferably, the lower monohydric alcohol in step S1 is any one of methanol, ethanol, propanol and butanol.

[0012] Preferably, the polymerization inhibitor in step S1 is any one or more combinations of phenothiazine, hydroquinone, hydroquinone monomethyl ether, oxygen, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical, and tetramethylpiperidinyl nitroxide free radical phosphite triester.

[0013] Preferably, the reactive distillation tower in step S2 has 20-50 theoretical plates.

[0014] Preferably, in step S2, the reaction raw materials are added from the 10th to 20th trays of the reaction distillation tower, and the temperature is controlled at 90-100°C.

[0015] Preferably, the acrylic acid content in the mixture flowing out from the top of the reactive distillation tower in step S2 is less than 0.5%.

[0016] Preferably, the dehydration device in step S2 is a molecular sieve membrane separation device.

[0017] The present invention provides a method for catalytically synthesizing acrylic acid esters from acrylic acid and low monohydric alcohols, which has the following advantages over the prior art:

[0018] The invention uses a strongly acidic cationic resin D72 as a catalyst and uses a molecular sieve membrane separation device for dehydration without the need for large amounts of water washing, thereby eliminating the need for a washing tower and saving energy consumption. In addition, the ratio of acrylic acid to low-order monohydric alcohol is appropriate, the content of acrylic acid in the mixture after esterification is less than 0.5%, and the need for a deacidification tower comprehensively improves the preparation efficiency of acrylic ester. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a production flow chart of the catalytic synthesis of acrylic ester. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the following examples, the molecular sieve membrane separation device adopts the pervaporation separation technology (Ningbo Xinyuan Membrane Industry Co., Ltd.).

[0022] Embodiment 1:

[0023] Methyl acrylate synthesis:

[0024] (1) 67.0% of acrylic acid, 32.8% of methanol (the molar ratio of acrylic acid to methanol is 1:1.1), 0.1% of phenothiazine and 0.1% of hydroquinone were used as a feed mixture according to weight percentage, and the feed mixture was added to a reaction distillation tower (diameter 50 mm, height 1000 mm, 40 trays) filled with strong acid cationic resin D72 (Secosase Co., Ltd.), and 600 g / h was added to the 20th tray of the reaction distillation tower, and the temperature of the 20th tray was maintained at 90° C.;

[0025] The composition of the vapor distilled from the top of the reactive distillation tower was detected (by weight): 16.4% water, 79.2% methyl acrylate, 0.5% acrylic acid, and 3.9% methanol;

[0026] The composition (weight percentage) of the bottom material of the reactive distillation tower was detected as follows: 44.1% acrylic acid, 37.5% acrylic acid dimer, 6.5% methyl acrylate, 2.6% methanol, 6.5% water, and 2.8% other components; and the bottom material was transported to an acrylic acid recombination and decomposition tower for recovery at a rate of 12 g / h.

[0027] (2) The steam distilled from the top of the reactor enters the molecular sieve membrane for separation and dehydration at 588 g / h;

[0028] The composition of the mixture after dehydration was detected (weight percentage): 94.7% methyl acrylate, 0.6% acrylic acid, 4.7% methanol;

[0029] After the dehydrated mixture is condensed, 0.1% of phenothiazine and 0.1% of hydroquinone by weight of the total mixture are added, a portion of which is returned to the top of the reactive distillation tower at a rate of 50 g / h as reflux liquid, and the other portion is transported to the light removal tower;

[0030] The components of the distillate removed from the top of the light-removal tower were detected (weight percentage): 80.3% methanol, 19.7% methyl acrylate, which was transported back to the reactive distillation tower;

[0031] The composition of the bottom material of the light removal tower was detected (weight percentage): 98.1% methyl acrylate, 0.5% methanol, 0.7% acrylic acid, and 0.7% heavy components.

[0032] (3) The bottom material of the light removal tower is transported to a purification tower for purification. The composition of the distillate at the top of the tower is detected (by weight percentage): 99.82% methyl acrylate, 0.02% acrylic acid, 0.01% methanol, and 0.15% other components. The bottom material is returned to the reactive distillation tower.

[0033] The acrylic acid conversion rate was 98.4%.

[0034] Embodiment 2:

[0035] Methyl acrylate synthesis:

[0036] (1) 65.1% of acrylic acid, 34.7% of methanol (the molar ratio of acrylic acid to methanol is 1:1.2), 0.1% of phenothiazine and 0.1% of hydroquinone were used as a feed mixture according to weight percentage, and the feed mixture was added to a reaction distillation tower (diameter 50 mm, height 1000 mm, 40 trays) filled with strong acid cationic resin D72 (Secosase Co., Ltd.), and 600 g / h was added to the 20th tray of the reaction distillation tower, and the temperature of the 20th tray was maintained at 90° C.;

[0037] The composition of the vapor distilled from the top of the reactive distillation tower was detected (by weight): 16.0% water, 76.9% methyl acrylate, 0.45% acrylic acid, and 6.65% methanol;

[0038] The composition (weight percentage) of the bottom material of the reactive distillation tower was detected as follows: 46.5% acrylic acid, 35.6% acrylic acid dimer, 5.6% methyl acrylate, 3.9% methanol, 5.8% water and 2.6% other components, and the bottom material was transported to the acrylic acid recombination and splitting tower for recovery at a rate of 10 g / h.

[0039] (2) The steam distilled from the top of the reactor enters the molecular sieve membrane for separation and dehydration at 590 g / h;

[0040] The composition of the mixture after dehydration was detected (weight percentage): 91.6% methyl acrylate, 0.5% acrylic acid, 7.9% methanol;

[0041] After the dehydrated mixture is condensed, 0.1% phenothiazine and 0.1% hydroquinone based on the total mass of the mixture are added, one part of which is returned to the top of the distillation tower as reflux liquid at a rate of 50 g / h, and the other part is transported to the light removal tower;

[0042] The components of the distillate removed from the top of the light removal tower were detected (weight percentage): 85.3% methanol, 14.7% methyl acrylate; the distillate was transported back to the reactive distillation tower;

[0043] The composition of the bottom material of the light removal tower was detected (weight percentage): 98.1% methyl acrylate, 0.6% methanol, 0.7% acrylic acid, and 0.6% heavy components;

[0044] (3) The bottom material of the light removal tower is transported to a purification tower for purification. The composition of the distillate at the top of the tower is detected (by weight percentage): 99.83% methyl acrylate, 0.02% acrylic acid, 0.01% methanol, and 0.14% other components. The bottom material is returned to the reactive distillation tower.

[0045] The acrylic acid conversion rate was 98.9%.

[0046] Embodiment 3:

[0047] Methyl acrylate synthesis:

[0048] (1) 59.9% of acrylic acid, 39.9% of methanol (the molar ratio of acrylic acid to methanol is 1:1.5), 0.1% of phenothiazine and 0.1% of hydroquinone were used as a feed mixture according to weight percentage, and the feed mixture was added to a reaction distillation tower (diameter 50 mm, height 1000 mm, 40 trays) filled with strong acid cationic resin D72 (Secosase Co., Ltd.), and 600 g / h was added to the 20th tray of the reaction distillation tower, and the temperature of the 20th tray was maintained at 90° C.;

[0049] The composition of the vapor distilled from the top of the reactive distillation tower (percent by weight) was as follows: 14.8% water, 70.8% methyl acrylate, 0.4% acrylic acid, and 14.0% methanol;

[0050] The composition of the bottom material of the reactive distillation tower was detected (weight percentage): 51.1% acrylic acid, 32.5% acrylic acid dimer, 4.8% methyl acrylate, 4.3% methanol, 5.0% water and 2.3% other components; and the bottom material was transported to the acrylic acid recombination and decomposition tower for recovery at 6 g / h.

[0051] (2) The steam distilled from the top of the reactor enters the molecular sieve membrane for separation and dehydration at 594 g / h;

[0052] The composition of the mixture after dehydration was detected (weight percentage): 83.1% methyl acrylate, 0.5% acrylic acid, 16.4% methanol;

[0053] After the dehydrated mixture is condensed, 0.1% phenothiazine and 0.1% hydroquinone are added to the total weight of the mixture, a portion of which is returned to the top of the distillation tower as reflux liquid at a rate of 50 g / h, and the other portion is transported to the light removal tower;

[0054] The components of the distillate removed from the top of the light-removal tower were detected (weight percentage): 90.6% methanol, 9.4% methyl acrylate, which was transported back to the reactive distillation tower;

[0055] The components of the bottom material of the light removal tower were detected (weight percentage): 98.2% methyl acrylate, 0.7% methanol, 0.6% acrylic acid, and 0.5% heavy components.

[0056] (3) The bottom material of the light removal tower is transported to a purification tower for purification. The composition of the distillate at the top of the tower is detected (by weight percentage): 99.81% methyl acrylate, 0.02% acrylic acid, 0.01% methanol, and 0.16% other components. The bottom material is returned to the reactive distillation tower.

[0057] The acrylic acid conversion rate was 99.6%.

[0058] Embodiment 4:

[0059] Ethyl acrylate synthesis:

[0060] (1) 58.6% of acrylic acid, 41.2% of ethanol (the molar ratio of acrylic acid to ethanol is 1:1.1), 0.1% of phenothiazine and 0.1% of hydroquinone were used as a feed mixture according to weight percentage, and the feed mixture was added to a reaction distillation tower (diameter 50 mm, height 1000 mm, 40 trays) filled with strong acid cationic resin D72 (Secosase Co., Ltd.), and 600 g / h was added to the 20th tray of the reaction distillation tower, and the temperature of the 20th tray was maintained at 100° C.;

[0061] The composition of the vapor distilled from the top of the reactive distillation tower was detected (by weight): 14.3% water, 80.2% ethyl acrylate, 0.4% acrylic acid, 5.1% ethanol;

[0062] The composition (weight percentage) of the bottom material of the reactive distillation tower was detected as follows: 38.2% acrylic acid, 41.8% acrylic acid dimer, 6.6% ethyl acrylate, 3.6% ethanol, 6.8% water and 3.0% other components; and the bottom material was transported to an acrylic acid recombination and splitting tower for recovery at a rate of 12 g / h.

[0063] (2) The steam distilled from the top of the reactor enters the molecular sieve membrane for separation and dehydration at 588 g / h;

[0064] The composition of the mixture after dehydration was detected (weight percentage): 93.6% ethyl acrylate, 0.5% acrylic acid, 5.9% ethanol;

[0065] After the dehydrated mixture is condensed, 0.1% phenothiazine and 0.1% hydroquinone are added to the total weight of the mixture, a portion of which is returned to the top of the reactive distillation tower at a rate of 50 g / h as reflux liquid, and the other portion is transported to the light removal tower;

[0066] The components of the distillate removed from the top of the light removal tower were detected (weight percentage): 78.6% ethanol, 21.4% ethyl acrylate, which was transported back to the reactive distillation tower;

[0067] The composition of the bottom material of the light removal tower was detected (weight percentage): 98.1% ethyl acrylate, 0.5% ethanol, 0.6% acrylic acid, and 0.8% heavy components.

[0068] (3) The bottom material of the light removal tower is transported to the purification tower for purification. The composition of the distillate at the top of the tower is detected (by weight percentage): 99.82% ethyl acrylate, 0.02% acrylic acid, 0.01% ethanol, and 0.15% other components. The bottom material is returned to the reactive distillation tower.

[0069] The acrylic acid conversion rate was 98.3%.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for catalytically synthesizing acrylic acid esters from acrylic acid and lower monohydric alcohols, characterized in that: The method for catalytic synthesis of acrylic acid ester comprises the following steps: S1. The reaction raw materials are arranged in the following proportions: the molar ratio of acrylic acid to lower monohydric alcohol is 1:1.1-1.5, and the polymerization inhibitor accounts for 0.05-0.1% by weight of the total reaction raw materials; S2, adding the above reaction raw materials into a reaction distillation tower filled with strong acid cationic resin D72 for reaction distillation, the steam distilled from the top of the tower enters a molecular sieve membrane separation device for dehydration, and the bottom material is transported to an acrylic acid recombination and splitting tower for recovery; S3, condensing the dehydrated mixture and adding a polymerization inhibitor, a part of which enters the top of the reactive distillation tower as reflux liquid, and the other part is transported to the light removal tower for treatment; S4, the distillate removed from the top of the light removal tower is transported back to the reactive distillation tower, and the bottom material is transported to the purification tower for purification, wherein the distillate from the top of the purification tower is high-purity acrylate, and the bottom material is returned to the reactive distillation tower.

2. The method for catalytic synthesis of acrylate according to claim 1, characterized in that: In step S1, the lower monohydric alcohol is any one of methanol, ethanol, propanol and butanol.

3. The method for catalytic synthesis of acrylate according to claim 1, characterized in that: In step S1, the polymerization inhibitor is any one or more combinations of phenothiazine, hydroquinone, hydroquinone monomethyl ether, oxygen, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl nitroxide free radical, and tetramethylpiperidinyl nitroxide free radical phosphite triester.

4. The method for catalytic synthesis of acrylic acid ester according to claim 1, characterized in that: The reactive distillation tower in step S2 has 20-50 theoretical plates.

5. The method for catalytic synthesis of acrylate according to claim 1, characterized in that: In step S2, the reaction raw materials are added from the 10th to 20th trays of the reaction distillation tower, and the temperature is controlled at 90-100°C.

6. The method for catalytic synthesis of acrylate according to claim 1, characterized in that: In the step S2, the acrylic acid content in the mixture flowing out from the top of the reactive distillation tower is less than 0.5%.

7. The method for catalytic synthesis of acrylic acid ester according to claim 1, characterized in that: The dehydration device in step S2 is a molecular sieve membrane separation device.

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