Purification method and device for benzophenone tetracarboxylic acid

Abstract

The present invention relates to the technical field of purification of benzophenone tetracarboxylic acid, and specifically to a method and device for purifying benzophenone tetracarboxylic acid. Supercritical ethanol is used as a purification fluid to reach a subcritical or supercritical state. Since heavy metal impurities and coloring substances are insoluble in supercritical ethanol, and benzophenone tetracarboxylic acid has good solubility, benzophenone tetracarboxylic acid is taken out with the supercritical fluid, the pressure is reduced in a separation kettle I, benzophenone tetracarboxylic acid and supercritical fluid are separated, ethanol is distilled at high temperature, a filter is set at the bottom of the separation kettle I, benzophenone tetracarboxylic acid is precipitated, and ethanol is recovered through the filter; supercritical carbon dioxide is used for secondary purification, the product and ethanol are taken away, and further separation is performed in the separation kettle II, and the high-heat carbon dioxide takes away the ethanol, thereby achieving the purpose of rapid drying. The supercritical fluid is recycled and reused to reduce energy consumption. The purity of the purified benzophenone tetracarboxylic acid can reach more than 99%, and the heavy metal ion concentration is less than 1ppm.

Description

Technical Field

[0001] The invention relates to the technical field of purification of benzophenone tetracarboxylic acid, and in particular to a method and a device for purifying benzophenone tetracarboxylic acid. Background Art

[0002] Benzophenone tetracarboxylic acid is an important chemical raw material, mostly used to prepare matrix resins and high-temperature resistant polyesters for advanced composite materials. This type of material has a wide temperature resistance range and excellent corrosion resistance, radiation resistance, insulation, impact resistance and other properties. It can be used to manufacture structural parts, laminates, films, adhesives, coatings, insulation materials and reinforcement materials, etc. It is widely used in aviation, aerospace, electronics, electrical, shipbuilding, automobiles, precision machinery and other fields, and has broad market prospects at home and abroad. However, in the field of semiconductors and high-end precision instruments, with the rapid promotion of high integration and the improvement of product qualification rate, it is strongly required that the materials used in this field do not contain or must meet the metal content standards. Therefore, reducing the metal content of the material has become a top priority.

[0003] Chinese patent CN103626727B adopts condensation filtration, then washes with anhydrous ethanol, filters to remove insoluble matter, distills, concentrates and cools to precipitate solids, the ratio of ethanol to benzophenone tetracarboxylic acid reaches more than 1:15, a large amount of anhydrous ethanol is required, and the solvent recycling rate is low; Chinese patent CN112979446A separates the crystalline product, and then uses water to wash to remove by-products. After purification, the by-products are not completely separated, and the product purity is low; Chinese patent CN1212322C uses potassium permanganate as a catalyst, and the post-treatment process uses 800mL (1:1, V:V) of pyridine and water boiling mixture to wash manganese dioxide twice, acidify with concentrated hydrochloric acid to pH=0.5, heat and boil for 1.5 hours, cool to room temperature, filter, collect the precipitated solids, and wash with water to neutrality, dry at 120°C, adjust the pH value, and use hydrochloric acid to acidify in a ratio of 1:1. The purification solvent is more harmful, the process is complicated, and it is not environmentally friendly.

[0004] The above purification methods have the disadvantages of large solvent usage, difficulty in recycling, low recycling rate, poor color, inability to remove residues, and especially high metal ion content. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for purifying benzophenone tetracarboxylic acid, which has simple process, energy saving and environmental protection, and small amount of solvent used, and overcomes the defects of the prior method such as high energy consumption, poor color, inability to remove residues, and high metal ion content; the present invention also provides a device used in the purification method.

[0006] The method for purifying benzophenone tetracarboxylic acid of the present invention adopts one of the following steps:

[0007] (1) Using supercritical ethanol as the fluid: ethanol reaches a subcritical or supercritical state under the conditions of a pressure of 4-10 MPa and a temperature of 90-150° C. Since heavy metal impurities and coloring substances are insoluble in supercritical ethanol, and benzophenone tetracarboxylic acid has a good solubility in supercritical ethanol, benzophenone tetracarboxylic acid is taken out with the supercritical fluid, and the pressure is reduced in a separation kettle, benzophenone tetracarboxylic acid and the supercritical fluid are separated, and ethanol is distilled at a high temperature. A filter is provided at the bottom of the separation kettle, benzophenone tetracarboxylic acid is precipitated, and ethanol is recovered through the filter;

[0008] (2) Using supercritical carbon dioxide as the fluid: carbon dioxide reaches a subcritical or supercritical state under the conditions of a pressure of 4-10 MPa and a temperature of 90-150° C. Since heavy metal impurities and coloring substances are insoluble in supercritical carbon dioxide, and benzophenone tetracarboxylic acid has a good solubility in supercritical carbon dioxide, benzophenone tetracarboxylic acid is taken out with the supercritical fluid, and the pressure is reduced in a separation kettle, benzophenone tetracarboxylic acid and the supercritical fluid are separated, and the product is dried by carbon dioxide at high temperature. A filter is provided at the bottom of the separation kettle, benzophenone tetracarboxylic acid is precipitated, and carbon dioxide is recovered through the filter;

[0009] (3) First, purify using step (1), and then purify using step (2).

[0010] In step (1), the amount of ethanol used is 10 times the mass of the raw material benzophenone tetracarboxylic acid.

[0011] The product after ethanol purification contains ethanol, which is secondary purified by supercritical carbon dioxide to take away the product and ethanol, and further separated in separation reactor II. The high-heat carbon dioxide takes away the ethanol, thereby achieving the purpose of rapid drying. The supercritical fluid is then recovered for recycling, reducing energy consumption. The purity of benzophenone tetracarboxylic acid after purification can reach more than 99%, and the heavy metal ion concentration is less than 1ppm.

[0012] Preferably, when the concentration of heavy metals and coloring substances remaining in benzophenone tetracarboxylic acid is greater than 100 ppm, supercritical ethanol is first used for purification, and then supercritical CO is used for purification. 2 Secondary purification improves product purity, i.e. first adopting step (1) and then adopting step (2).

[0013] Preferably, when the concentration of heavy metals and coloring substances remaining in benzophenone tetracarboxylic acid is less than 20 ppm, supercritical CO 2 Secondary purification to improve product purity.

[0014] The filter screen involved above is a 2000 mesh filter screen.

[0015] The device used in the method for purifying benzophenone tetracarboxylic acid of the present invention comprises: a CO 2Gas cylinder, CO 2 The gas cylinder is connected to the high-pressure pump, filter I, heater I, flow regulating valve, autoclave, separation kettle I, heater II, buffer kettle, and filter II in sequence through pipelines; the pipeline between filter I and heater I is also connected to a solvent tank and a plunger pump; separation kettle I is also connected to separation kettle II, and separation kettle II is connected to buffer kettle; heater I is also connected to separation kettle I; filter I is also connected to the pipeline between buffer kettle and filter II

[0016] in:

[0017] Preferably, a stop valve is provided on the outlet pipeline of the solvent tank; a stop valve is provided on the pipeline between the heater I and the flow regulating valve; a stop valve is provided on the pipeline between the autoclave and the separation kettle I; a stop valve and a stop valve are provided on the pipeline between the separation kettle I and the heater II; a stop valve and a stop valve are provided on the pipeline between the filter I and the filter II; a stop valve is provided on the pipeline between the heater I and the separation kettle I; a stop valve is provided on the pipeline between the separation kettle I and the separation kettle II; a stop valve is provided on the pipeline between the separation kettle II and the heater II; a branch line is connected to the autoclave, and a stop valve is provided on the branch line; CO 2 A stop valve is provided on the outlet pipeline of the gas cylinder.

[0018] Preferably, the autoclave adopts an automatic switching device.

[0019] Preferably, the stop valve and the high-pressure pump are controlled by an automated device.

[0020] Preferably, the CO 2 A one-way valve is provided on the pipeline between the gas cylinder and the high-pressure pump; a one-way valve is provided on the pipeline between the filter I and the heater I; a one-way valve is provided on the pipeline between the heater I and the flow regulating valve; a one-way valve is provided on the pipeline between the buffer kettle and the filter II.

[0021] Preferably, the one-way valve is controlled by an automated device.

[0022] The purification method of benzophenone tetracarboxylic acid of the present invention has two routes, one is: CO 2 The supercritical CO2 is connected in sequence with a gas cylinder, a high-pressure pump, a filter I, a heater I, a flow control valve, a high-pressure autoclave, a separation autoclave, a heater II, a buffer autoclave, and a filter II. 2 Purification line; second, a supercritical ethanol purification line in which a solvent tank, a plunger pump, a heater I, a flow regulating valve, a high-pressure autoclave, a separation autoclave, a heater II, a buffer autoclave, and a filter I are sequentially connected.

[0023] After ethanol purification, carbon dioxide can be used for secondary purification, and the purified product can be dried at the same time to save energy. The process flow is: CO 2The gas cylinder, high-pressure pump, filter I, heater I, separation kettle I, separation kettle II, heater II, buffer kettle and filter II are connected in sequence.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The purification method of the present invention provides a new idea. The solubility of the residual solvent and the colored impurities in the supercritical fluid is low, and the solubility of the product in the supercritical fluid is high, thereby improving the purity of benzophenone tetracarboxylic acid and reducing the heavy metal concentration. After purification, the purity of benzophenone tetracarboxylic acid can reach more than 99%, and the heavy metal ion concentration is less than 1ppm.

[0026] 2. The purification method of the present invention has a simple process, is energy-saving and environmentally friendly, and avoids the defects of the traditional method, such as large amount of solvent used, difficulty in recovery, low yield, high energy consumption, poor color, inability to remove residues, and high metal ion content. It is a new method that is safe, environmentally friendly and sustainable.

[0027] 3. The device of the present invention has a simple structure, reasonable design and is easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a purification device for benzophenone tetracarboxylic acid of the present invention;

[0029] In the figure: 1. CO 2 Gas cylinder; 2. High-pressure pump; 3. Filter I; 4. Solvent tank; 5. Plunger pump; 6. Heater I; 7. Flow regulating valve; 8. Autoclave; 9. Separation kettle I; 10. Heater II; 11. Buffer kettle; 12. Filter II; 13. Separation kettle II; D1-D4, one-way valve; A1-A12, stop valve. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments to facilitate a better understanding of the present invention, but the present invention is not limited thereto.

[0031] like Figure 1 As shown, the device used in the purification method of benzophenone tetracarboxylic acid includes a CO 2 Gas cylinder 1, CO 2 The gas cylinder 1 is connected to the high-pressure pump 2, the filter I3, the heater I6, the flow regulating valve 7, the autoclave 8, the separation kettle I9, the heater II10, the buffer kettle 11 and the filter II12 in sequence through pipelines; the solvent tank 4 and the plunger pump 5 are also connected to the pipeline between the filter I3 and the heater I6; the separation kettle I9 is ​​also connected to the separation kettle II13, and the separation kettle II13 is connected to the buffer kettle 11; the heater I6 is also connected to the separation kettle I9; the filter I3 is also connected to the pipeline between the buffer kettle 11 and the filter II12.

[0032] A stop valve A1 is provided on the outlet pipeline of the solvent tank 4; a stop valve A2 is provided on the pipeline between the heater Ⅰ6 and the flow regulating valve 7; a stop valve A3 is provided on the pipeline between the autoclave 8 and the separation kettle Ⅰ9; a stop valve A4 and a stop valve A5 are provided on the pipeline between the separation kettle Ⅰ9 and the heater Ⅱ10; a stop valve A6 and a stop valve A10 are provided on the pipeline between the filter Ⅰ3 and the filter Ⅱ12; a stop valve A7 is provided on the pipeline between the heater Ⅰ6 and the separation kettle Ⅰ9; a stop valve A8 is provided on the pipeline between the separation kettle Ⅰ9 and the separation kettle Ⅱ13; a stop valve A9 is provided on the pipeline between the separation kettle Ⅱ13 and the heater Ⅱ10; a branch line is connected to the autoclave 8, and a stop valve A11 is provided on the branch line; CO 2 A stop valve A12 is provided on the outlet pipeline of the gas cylinder 1.

[0033] The autoclave 8 adopts an automatic switch device.

[0034] The stop valves A1-A12 and the high-pressure pump 2 are controlled by an automated device.

[0035] CO 2 A one-way valve D1 is provided on the pipeline between the gas cylinder 1 and the high-pressure pump 2; a one-way valve D2 is provided on the pipeline between the filter Ⅰ3 and the heater Ⅰ6; a one-way valve D3 is provided on the pipeline between the heater Ⅰ6 and the flow regulating valve 7; a one-way valve D4 is provided on the pipeline between the buffer kettle 11 and the filter Ⅱ12.

[0036] The one-way valves D1-D4 are controlled by an automatic device.

[0037] Example 1

[0038] When the concentration of heavy metals and coloring substances in benzophenone tetracarboxylic acid is greater than 100 ppm, it is first purified by supercritical ethanol and then by supercritical CO 2 Secondary purification to improve product purity, as follows:

[0039] Open the stop valve A2-A12 before use and pass CO 2 Carry out purging, close the high-pressure pump 2 after 5 minutes, open the cover of the autoclave 8 by using the control system, put in benzophenone tetracarboxylic acid, close the cover of the autoclave 8, open the stop valves A1-A5 and the high-pressure pump 2 in sequence, control the opening of the flow regulating valve 7, turn on the heater Ⅰ6 to control the temperature at 90-150°C, open the plunger pump 5 to pass ethanol, control the opening of the flow regulating valve 7 to control the pressure in the autoclave 8 at 4-10MPa, benzophenone tetracarboxylic acid flows out of the autoclave 8 with supercritical ethanol, ethanol and benzophenone tetracarboxylic acid are separated in the separation kettle Ⅰ9, and ethanol is recycled in a gaseous state at high temperature, then close the plunger pump 5 and the stop valves A1-A4, open the stop valves A7-A9 and the high-pressure pump 2 in sequence, pass CO 2 , CO2 Under the conditions of pressure 4-10MPa and temperature 90-150℃, benzophenone tetracarboxylic acid and CO 2 In the separation reactor II13, CO 2 After being recycled through heater II 10, buffer kettle 11 and filter II 12, the sample is taken out and the heavy metal ion concentration of the sample is tested to be less than 1 ppm, thereby achieving the purpose of purifying the product.

[0040] Example 2

[0041] When the concentration of heavy metals and coloring substances in benzophenone tetracarboxylic acid is less than 20 ppm, supercritical CO 2 Purification to improve product purity, as follows:

[0042] Open the stop valve A2-A12 to pass CO before use 2 After 5 minutes, the high-pressure pump 2 and the stop valves A1-A12 are closed. The cover of the autoclave 8 is opened by the control system, and benzophenone tetracarboxylic acid is added. The cover of the autoclave 8 is closed, and the stop valves A2-A6, the stop valve A12, and the high-pressure pump 2 are opened in sequence. The opening of the flow regulating valve 7 is controlled, and the heater I6 is turned on. The temperature is controlled at 90-150°C, and the pressure in the autoclave 8 is 4-10MPa. Benzophenone tetracarboxylic acid is heated by supercritical CO 2 Outflow of autoclave 8, CO 2 and benzophenone tetracarboxylic acid in the separation reactor Ⅰ9, CO 2 The gas is recycled through heater II 10 and buffer kettle 11 in turn, and samples are taken out. The heavy metal ion concentration of the sample is tested to be less than 1 ppm, thereby achieving the purpose of purifying the product.

[0043] Of course, the above contents are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical contents to change or modify them into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for purifying benzophenonetetracarboxylic acid, characterized in that: The residual heavy metal and coloring matter concentration is less than 20ppm. Benzophenone tetracarboxylic acid is purified by the following steps: Supercritical carbon dioxide is used as the fluid: carbon dioxide reaches a subcritical or supercritical state under the conditions of a pressure of 4-10MPa and a temperature of 90-150°C. Since heavy metal impurities and coloring substances are insoluble in supercritical carbon dioxide, and benzophenone tetracarboxylic acid has a good solubility in supercritical carbon dioxide, benzophenone tetracarboxylic acid is taken out with the supercritical fluid, and the pressure is reduced in the separation kettle, benzophenone tetracarboxylic acid and the supercritical fluid are separated, and the product is dried by carbon dioxide at high temperature. A filter is arranged at the bottom of the separation kettle, benzophenone tetracarboxylic acid is precipitated, and carbon dioxide is recovered through the filter.

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