A method for improving the recovery of acrylic acid recombination split

Abstract

The present application relates to the field of acrylic acid recovery, in particular to a method for improving the recovery rate of acrylic acid heavy component cracking, comprising the following steps: (1) injecting acrylic acid heavy component into a reaction kettle, and adding modified biochar catalyst into the reaction kettle, and cracking reaction until no more discharge, achieving the primary recovery of acrylic acid; (2) after the reaction kettle is released vacuum, dropwise adding hot water for redistillation, completing the secondary recovery of acrylic acid; (3) the primary recovered acrylic acid and the secondary recovered acrylic acid are kept in a flowing state by a circulating pump to prevent polymerization. The present application adds modified biochar catalyst in the early stage of acrylic acid heavy component cracking reaction, which is conducive to the rapid and sufficient cracking of acrylic acid dimers to generate acrylic acid, then hot water is supplemented in the later stage to reduce the viscosity of the remaining residual liquid, promote the cracking reaction and form a water-acrylic acid azeotropic system at the same time, so that the hot water with acrylic acid continues to distill and come out, thereby improving the recovery rate of acrylic acid.

Description

Technical Field

[0001] This invention relates to the field of acrylic acid recycling technology, and more specifically to a method for improving the recovery rate of acrylic acid recombination and decomposition. Background Technology

[0002] Acrylic acid and its esters, as important industrial derivatives of propylene, have seen rapid development in recent years, greatly enriching people's lives. However, the production process generates a large amount of heavy acrylic acid or acrylate components. Heavy acrylic acid components, also known as waste oil, refer to the residue from the bottom of the depolymerization tower after treatment by an acrylic acid recovery system consisting of a dimer decomposition tank and a thin-film evaporator. It mainly contains acrylic acid dimers, polymerization inhibitors, maleic acid, a small amount of acrylic acid, and other relatively heavy components.

[0003] Common recovery methods include high-temperature pyrolysis and acid catalysis. Currently, acrylic acid heavy components in pyrolysis plants are typically recovered by direct pyrolysis using steam heating, with the remaining residue sent to incineration. However, this method results in a low acrylic acid recovery rate. Therefore, we propose a method to improve the recovery rate of acrylic acid heavy component pyrolysis. Summary of the Invention

[0004] (i) In view of the shortcomings of the prior art, the present invention provides a method for improving the recovery rate of acrylic acid recombination and decomposition. Modified biochar catalyst is added in the early stage of decomposition and hot water is added in the later stage, thereby improving the recovery rate of acrylic acid.

[0005] (II) To achieve the above objectives, the present invention provides the following technical solution: A method for improving the recovery rate of acrylic acid recombination and decomposition, comprising the following steps:

[0006] (1) The heavy components of acrylic acid are injected into the reactor and a modified biochar catalyst is added to the reactor. The pyrolysis reaction continues until no more material is discharged, thus achieving the initial recovery of acrylic acid.

[0007] (2) After evacuating the reactor, add hot water droplets for re-distillation to complete the secondary recovery of acrylic acid;

[0008] (3) The acrylic acid recovered initially and the acrylic acid recovered in the second stage are kept in a flowing state by a circulation pump to prevent polymerization.

[0009] Preferably, in step (1), the pyrolysis reaction temperature is (140~170)℃ and the pyrolysis reaction pressure is (-0.085~-0.1)MPa.

[0010] Preferably, in step (1), the modified biochar catalyst accounts for (4-10)% of the total mass of the heavy acrylic acid components.

[0011] Preferably, in step (1), the modified biochar catalyst is prepared as follows:

[0012] S1. Place the biochar particles into a tube furnace and introduce ozone into the tube furnace to etch the biochar particles to obtain pretreated biochar particles.

[0013] S2. The pretreated biochar particles are impregnated in ammonium sulfate solution, filtered, and then calcined to obtain the modified biochar catalyst.

[0014] Preferably, in step S1, the etching temperature is (120-140)℃, the etching time is (20-40)min, and the ozone flow rate is (130-150)ml / min.

[0015] Preferably, in step S2, the ammonium sulfate solution is composed of ammonium sulfate and deionized water at a ratio of (1:1) g / ml.

[0016] Preferably, in step (2), the hot water dripping time lasts for (8-12) hours.

[0017] Preferably, in step (2), the temperature of the hot water is (70-80)℃, and the amount of hot water added is 1 / 3 to 1 / 2 of the total mass of the acrylic acid heavy components.

[0018] (III) This invention provides a method for improving the recovery rate of acrylic acid recombination and decomposition, which has the following beneficial effects:

[0019] This invention adds a modified biochar catalyst in the early stage of the acrylic acid recombination and decomposition reaction, which is conducive to the rapid and more complete decomposition of acrylic acid dimers to generate acrylic acid. Subsequently, hot water is added in the later stage to reduce the viscosity of the remaining liquid, promote the decomposition reaction and form a water-acrylic acid azeotropic system, so that the hot water carries the acrylic acid to continue distillation, thereby improving the recovery rate of acrylic acid.

[0020] This invention treats biochar with ozone to form numerous micropores and cracks on its surface, and then impregnates it in an ammonium sulfate solution, so that the ammonium sulfate is tightly loaded onto the biochar to form a solid acid catalyst. After the reaction is completed, it is easy to separate from the residual liquid and is relatively convenient to recover. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Example 1

[0023] A method for preparing a modified biochar catalyst is as follows:

[0024] S1. Place the biochar particles into a tube furnace and introduce ozone into the tube furnace to etch the biochar particles to obtain pretreated biochar particles; wherein, the etching temperature is 120℃, the etching time is 20min, and the ozone flow rate is 130ml / min.

[0025] S2. The pretreated biochar particles are impregnated in an ammonium sulfate solution, filtered, and then calcined to obtain a modified biochar catalyst; wherein the ammonium sulfate solution is composed of ammonium sulfate and deionized water at a feed-to-liquid ratio of (1:1) g / ml.

[0026] Example 2

[0027] A method for preparing a modified biochar catalyst is as follows:

[0028] S1. Place the biochar particles into a tube furnace and introduce ozone into the tube furnace to etch the biochar particles to obtain pretreated biochar particles; wherein, the etching temperature is 140℃, the etching time is 40min, and the ozone flow rate is 150ml / min.

[0029] S2. The pretreated biochar particles are impregnated in an ammonium sulfate solution, filtered, and then calcined to obtain a modified biochar catalyst; wherein the ammonium sulfate solution is composed of ammonium sulfate and deionized water at a feed-to-liquid ratio of (1:1) g / ml.

[0030] Example 3

[0031] A method for improving the recovery rate of acrylic acid recombination and decomposition includes the following steps:

[0032] (1) The heavy acrylic acid components are injected into the reactor and a modified biochar catalyst is added to the reactor. The pyrolysis reaction continues until no more material is discharged, thus achieving the initial recovery of acrylic acid. The pyrolysis reaction temperature is 160℃ and the pyrolysis reaction pressure is -0.095MPa. The modified biochar catalyst accounts for 8% of the total mass of the heavy acrylic acid components.

[0033] (2) After the reactor is evacuated, hot water is added dropwise for re-distillation to complete the secondary recovery of acrylic acid; the hot water addition time is 10 hours; the temperature of the hot water is 80℃, and the amount of hot water added is 1 / 2 of the total mass of the acrylic acid heavy components.

[0034] (3) The acrylic acid recovered initially and the acrylic acid recovered in the second stage are kept in a flowing state by a circulation pump to prevent polymerization.

[0035] In this embodiment, the modified biochar catalyst from Example 2 was used. The recovery rate of the modified biochar catalyst reached 89%.

[0036] Example 4

[0037] A method for improving the recovery rate of acrylic acid recombination and decomposition includes the following steps:

[0038] (1) The heavy acrylic acid components are injected into the reactor and a modified biochar catalyst is added to the reactor. The pyrolysis reaction continues until no more material is discharged, thus achieving the initial recovery of acrylic acid. The pyrolysis reaction temperature is 140℃ and the pyrolysis reaction pressure is -0.085MPa. The modified biochar catalyst accounts for 4% of the total mass of the heavy acrylic acid components.

[0039] (2) After the reactor is evacuated, hot water is added dropwise for re-distillation to complete the secondary recovery of acrylic acid; the hot water addition time is 8 hours; the temperature of the hot water is 70℃, and the amount of hot water added is 1 / 3 of the total mass of the acrylic acid heavy components.

[0040] (3) The acrylic acid recovered initially and the acrylic acid recovered in the second stage are kept in a flowing state by a circulation pump to prevent polymerization.

[0041] In this embodiment, the modified biochar catalyst from Example 1 was used. The recovery rate of the modified biochar catalyst reached 85%.

[0042] Comparative Example 1

[0043] A method for improving the recovery rate of acrylic acid recombination and decomposition includes the following steps:

[0044] (1) The heavy acrylic acid components are injected into the reactor and a modified biochar catalyst is added to the reactor. The pyrolysis reaction continues until no more material is discharged, thus realizing the recovery of acrylic acid. The pyrolysis reaction temperature is 140℃ and the pyrolysis reaction pressure is -0.085MPa. The modified biochar catalyst accounts for 4% of the total mass of the heavy acrylic acid components.

[0045] (2) The recycled acrylic acid is kept in a flowing state by a circulation pump to prevent polymerization.

[0046] In this embodiment, the modified biochar catalyst from Example 2 was used. The recovery rate of the modified biochar catalyst reached 87%.

[0047] Comparative Example 2

[0048] A method for improving the recovery rate of acrylic acid recombination and decomposition includes the following steps:

[0049] (1) The heavy components of acrylic acid are injected into the reactor and the pyrolysis reaction continues until no more material is discharged, thus achieving the initial recovery of acrylic acid; wherein, the pyrolysis reaction temperature is 160℃ and the pyrolysis reaction pressure is -0.095MPa.

[0050] (2) After the reactor is evacuated, hot water is added dropwise for re-distillation to complete the secondary recovery of acrylic acid; the hot water addition time is 10 hours; the temperature of the hot water is 80℃, and the amount of hot water added is 1 / 2 of the total mass of the acrylic acid heavy components.

[0051] (3) The acrylic acid recovered initially and the acrylic acid recovered in the second stage are kept in a flowing state by a circulation pump to prevent polymerization.

[0052] Detection

[0053] 1. Calculate the recovery rate of acrylic acid in Examples 3-4 and Comparative Examples 1-2 using the following formula:

[0054] Acrylic acid recovery rate = Amount of acrylic acid separated by distillation / (Amount of acrylic acid in the heavy acrylic acid fraction + Amount of acrylic acid dimer in the heavy acrylic acid fraction). Specific results are shown in the table below.

[0055] Table 1 Recovery Rate

[0056] Example 3 86.4 Example 4 83.3 Comparative Example 1 76.8 Comparative Example 2 62.5

[0057] The embodiments disclosed herein are preferred embodiments, but are not limited thereto. Those skilled in the art can readily grasp the spirit of the present invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A method for improving the recovery rate of acrylic acid recombination and decomposition, characterized in that, Includes the following steps: (1) The heavy components of acrylic acid are injected into the reactor and a modified biochar catalyst is added to the reactor. The pyrolysis reaction continues until no more material is discharged, thus achieving the initial recovery of acrylic acid. In step (1), the modified biochar catalyst is prepared as follows: S1. Place the biochar particles into a tube furnace and introduce ozone into the tube furnace to etch the biochar particles to obtain pretreated biochar particles. S2. The pretreated biochar particles were impregnated in an ammonium sulfate solution, filtered, and then calcined to obtain a modified biochar catalyst. (2) After evacuating the reactor, add hot water droplets for re-distillation to complete the secondary recovery of acrylic acid; (3) The acrylic acid recovered initially and the acrylic acid recovered in the second stage are kept in a flowing state by circulating pumps to prevent polymerization.

2. The method for improving the recovery rate of acrylic acid recombination and decomposition as described in claim 1, characterized in that, In step (1), the pyrolysis reaction temperature is (140~170)℃ and the pyrolysis reaction pressure is (-0.085~-0.1)MPa.

3. The method for improving the recovery rate of acrylic acid recombination and decomposition as described in claim 1, characterized in that, In step (1), the modified biochar catalyst accounts for (4~10)% of the total mass of the acrylic acid heavy components.

4. The method for improving the recovery rate of acrylic acid recombination and decomposition as described in claim 1, characterized in that, In step S1, the etching temperature is (120~140)℃, the etching time is (20~40)min, and the ozone flow rate is (130~150)ml / min.

5. The method for improving the recovery rate of acrylic acid recombination and decomposition as described in claim 1, characterized in that, In step S2, the ammonium sulfate solution is composed of ammonium sulfate and deionized water at a ratio of (1:1) g / ml.

6. The method for improving the recovery rate of acrylic acid recombination and decomposition as described in claim 1, characterized in that, In step (2), the hot water dripping time lasts for (8~12) hours.

7. The method for improving the recovery rate of acrylic acid recombination and decomposition as described in claim 1, characterized in that, In step (2), the temperature of the hot water is (70~80)℃, and the amount of hot water added is 1 / 3~1 / 2 of the total mass of the acrylic acid heavy components.