A method for treating mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid

Abstract

The present invention belongs to the field of solid waste treatment technology, and provides a method for treating mixed solid waste produced by 3,3',4,4'-biphenyltetracarboxylic acid. The first reduced pressure sublimation of the present invention can remove phthalic anhydride and chlorophthalic dianhydride in the mixed solid waste produced by 3,3',4,4'-biphenyltetracarboxylic acid. Alkali dissolution can remove the carbonized material produced during the first reduced pressure sublimation process. The second reduced pressure sublimation can purify and dehydrate the crude 3,3',4,4'-biphenyltetracarboxylic acid to obtain refined 3,3',4,4'-biphenyltetracarboxylic dianhydride, which can be sold as a product. The treatment method provided by the present invention can recycle 3,3',4,4'-biphenyltetracarboxylic dianhydride, realize the resource utilization of the mixture solid waste, and has low cost, low energy consumption, and no generation of dioxin secondary pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment, and in particular to a method for treating mixed solid waste produced in the production of 3,3',4,4'-biphenyltetracarboxylic acid. Background Art

[0002] 3,3',4,4'-Biphenyldianhydride (BPDA), a polyimide monomer, can be polymerized with various amines to form polyimides. These polyimides are essential materials for wearable devices, foldable phones, and foldable computers. In recent years, with the rapid development of popular technologies such as 5G, wearable devices, foldable phones, and foldable computers, the demand for polyimides has increased significantly.

[0003] At present, 3,3',4,4'-biphenyl dianhydride is obtained by dehydrating 3,3',4,4'-biphenyl tetracarboxylic acid. The industrial synthesis method of 3,3',4,4'-biphenyl tetracarboxylic acid mainly uses phthalic anhydride to chlorinate to obtain a mixture of 4-chlorophthalic acid monosodium salt, and then dechlorination coupling and acid precipitation under the catalysis of precious metals to obtain crude biphenyl tetracarboxylic acid. About 1.1 tons of crude biphenyl tetracarboxylic acid can be refined to obtain 1 ton of fine biphenyl tetracarboxylic acid. Acid; at the same time, the refined mother liquor generated in the refining process of crude 3,3',4,4'-biphenyltetracarboxylic acid can be treated to recover 90kg of mixed solid waste of 3,3',4,4'-biphenyltetracarboxylic acid, chlorophthalic acid and phthalic acid; in the mixed solid waste, the content of 3,3',4,4'-biphenyltetracarboxylic acid is 63-65wt%, the content of phthalic acid is 34-36wt%, and the content of chlorophthalic acid is 1-1.4wt%.

[0004] Currently, incineration is the primary method for treating mixed solid waste. This method involves directly burning the mixed solid waste. However, because the mixed solid waste contains organochlorine, the incineration process produces dioxins, which require temperatures around 1100°C to completely decompose. This results in high treatment costs and energy consumption, and does not allow for the resource recovery of 3,3',4,4'-biphenyltetracarboxylic acid in the mixed solid waste. Summary of the Invention

[0005] In light of this, the present invention aims to provide a method for treating mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid. The method provided by the present invention can recover 3,3',4,4'-biphenyltetracarboxylic dianhydride, achieving resource utilization of the mixed solid waste with low cost and energy consumption, and without the generation of dioxin secondary pollutants.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for treating mixed solid waste produced in the production of 3,3',4,4'-biphenyltetracarboxylic acid, comprising the following steps:

[0008] Subliming the mixed solid waste produced by 3,3',4,4'-biphenyltetracarboxylic acid under first reduced pressure to obtain pretreated solid waste;

[0009] alkali-dissolving the pretreated solid waste to remove alkali-insoluble matter to obtain an alkaline solution;

[0010] The pH value of the alkaline solution is adjusted to acidic, and hot filtration is performed to obtain a crude product of 3,3',4,4'-biphenyltetracarboxylic acid;

[0011] The crude 3,3',4,4'-biphenyltetracarboxylic acid product is subjected to a second reduced pressure sublimation, the initial fraction is discarded, and the middle fraction is collected to obtain refined 3,3',4,4'-biphenyltetracarboxylic dianhydride;

[0012] The mass of the initial fraction is 5 to 10% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid;

[0013] The mass of the middle fraction is 70-80% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid.

[0014] Preferably, the temperature of the first reduced-pressure sublimation is 110-120° C., and the vacuum degree is 3-5 mmHg.

[0015] Preferably, the pH value of the alkaline dissolution is 12-14, and the temperature is 80-105°C.

[0016] Preferably, the mass concentration of the alkali solution used in the alkali dissolution is 20-30%.

[0017] Preferably, the method of removing alkali-insoluble matter is solid-liquid separation.

[0018] Preferably, the acidic pH value is 0.5 to 1.5.

[0019] Preferably, the temperature of the hot filtration is 70-80°C.

[0020] Preferably, the temperature of the second reduced-pressure sublimation is 230-240° C., and the vacuum degree is ≤1 mmHg.

[0021] The invention provides a method for treating mixed solid waste produced in the production of 3,3',4,4'-biphenyltetracarboxylic acid. The method comprises the following steps: subjecting the mixed solid waste produced in the production of 3,3',4,4'-biphenyltetracarboxylic acid to a first reduced-pressure sublimation to obtain pretreated solid waste; subjecting the pretreated solid waste to alkali dissolution to remove alkali-insoluble matter to obtain an alkaline solution; adjusting the pH value of the alkaline solution to acidity, and subjecting the solution to hot filtration to obtain a crude 3,3',4,4'-biphenyltetracarboxylic acid product; subjecting the crude 3,3',4,4'-biphenyltetracarboxylic acid product to a second reduced-pressure sublimation, discarding an initial fraction, and collecting a middle fraction to obtain refined 3,3',4,4'-biphenyltetracarboxylic dianhydride; the mass of the initial fraction is 5-10% of the weight of the 3,3',4,4'-biphenyltetracarboxylic acid; and the mass of the middle fraction is 70-80% of the weight of the 3,3',4,4'-biphenyltetracarboxylic acid. The first vacuum sublimation process of the present invention can remove phthalic anhydride (phthalic acid removes a molecule of water during sublimation to form phthalic anhydride) and chlorophthalic anhydride (chlorophthalic acid removes a molecule of water during sublimation to form chlorophthalic anhydride) from the mixed solid waste produced by the production of 3,3',4,4'-biphenyltetracarboxylic acid. Phthalic anhydride and chlorophthalic dianhydride can also be used to prepare monosodium 4-chlorophthalic acid, thereby improving resource utilization. Alkali dissolution can also remove carbonized materials produced during the first vacuum sublimation process. The second reduced-pressure sublimation process purifies and dehydrates the crude 3,3',4,4'-biphenyltetracarboxylic acid to obtain refined 3,3',4,4'-biphenyltetracarboxylic dianhydride. This refined 3,3',4,4'-biphenyltetracarboxylic dianhydride can be sold as a product, reducing the raw material cost of producing 3,3',4,4'-biphenyltetracarboxylic dianhydride. The treatment method provided by the present invention can recover 3,3',4,4'-biphenyltetracarboxylic dianhydride, achieving resource utilization of the solid waste mixture with low cost and energy consumption, and without the generation of dioxin secondary pollutants. DETAILED DESCRIPTION

[0022] The present invention provides a method for treating mixed solid waste produced in the production of 3,3',4,4'-biphenyltetracarboxylic acid, comprising the following steps:

[0023] Subliming the mixed solid waste produced by 3,3',4,4'-biphenyltetracarboxylic acid under first reduced pressure to obtain pretreated solid waste;

[0024] alkali-dissolving the pretreated solid waste to remove alkali-insoluble matter to obtain an alkaline solution;

[0025] The pH value of the alkaline solution is adjusted to acidic, and hot filtration is performed to obtain a crude product of 3,3',4,4'-biphenyltetracarboxylic acid;

[0026] The crude 3,3',4,4'-biphenyltetracarboxylic acid product is subjected to a second reduced pressure sublimation, the initial fraction is discarded, and the middle fraction is collected to obtain refined 3,3',4,4'-biphenyltetracarboxylic dianhydride;

[0027] The mass of the initial fraction is 5 to 10% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid;

[0028] The mass of the middle fraction is 70-80% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid.

[0029] In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0030] The present invention performs a first reduced-pressure sublimation on mixed solid waste produced in the production of 3,3',4,4'-biphenyltetracarboxylic acid to obtain pretreated solid waste.

[0031] In the present invention, the mixed solid waste produced from the production of 3,3',4,4'-biphenyltetracarboxylic acid preferably includes the following components in percentage by mass:

[0032] The content of 3,3',4,4'-biphenyltetracarboxylic acid is 63-65 wt%, the content of phthalic acid is 34-36 wt%, and the content of chlorophthalic acid is 1-1.4 wt%.

[0033] In the present invention, the temperature of the first reduced-pressure sublimation is preferably 110-120° C., and the vacuum degree is preferably 3-5 mmHg.

[0034] After the first reduced-pressure sublimation, the present invention preferably further comprises pulverizing the obtained kettle residue. In the present invention, the particle size of the pulverized material obtained after the pulverization is preferably ≤3 mm.

[0035] In the present invention, the first reduced-pressure sublimation can remove phthalic anhydride and chlorophthalic dianhydride from the mixed solid waste produced by the production of 3,3',4,4'-biphenyltetracarboxylic acid.

[0036] After obtaining the pretreated solid waste, the present invention performs alkali dissolution on the pretreated solid waste to remove alkali-insoluble matter to obtain an alkaline solution.

[0037] In the present invention, the pH value of the alkaline dissolution is preferably 12 to 14; the temperature is preferably 80 to 105° C., more preferably 85 to 100° C., and further preferably 90 to 95° C.; and the time is preferably 1 hour.

[0038] In a specific embodiment of the present invention, the alkali solution used in the alkali dissolution is preferably an inorganic strong alkali solution, more preferably a sodium hydroxide aqueous solution.

[0039] In the present invention, the mass concentration of the alkali solution used in the alkali dissolution is preferably 20-30%. In the present invention, the mass ratio of the alkali solution used in the alkali dissolution to the pre-treated solid waste is preferably 1:0.4-0.6 on a dry weight basis.

[0040] In the present invention, the method for removing the alkali-insoluble matter is solid-liquid separation; the method for removing the solid-liquid separation is preferably filtration.

[0041] In the present invention, the alkali dissolution can remove the carbides formed in the pretreated solid waste due to the first reduced pressure sublimation.

[0042] After obtaining the alkaline solution, the present invention adjusts the pH value of the alkaline solution to be acidic, and performs hot filtration to obtain a crude product of 3,3',4,4'-biphenyltetracarboxylic acid.

[0043] In the present invention, the acidic pH value is preferably 0.5 to 1.5. In the present invention, the temperature of the hot filtration is preferably 70 to 80°C.

[0044] After the hot filtration, the present invention preferably further comprises drying the obtained solid.

[0045] In the present invention, the mass percentage of 3,3',4,4'-biphenyltetracarboxylic acid in the crude 3,3',4,4'-biphenyltetracarboxylic acid product is ≥99.5%.

[0046] After obtaining the crude 3,3',4,4'-biphenyltetracarboxylic acid, the present invention performs a second reduced-pressure sublimation on the crude 3,3',4,4'-biphenyltetracarboxylic acid, discards the initial fraction, collects the middle fraction, and obtains refined 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0047] In the present invention, the temperature of the second reduced-pressure sublimation is preferably 230-240° C., and the vacuum degree is preferably ≤1 mmHg.

[0048] In the present invention, the mass of the initial fraction is 5-10% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid; the mass of the middle fraction is 70-80% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid.

[0049] In the present invention, the collection method of the refined 3,3',4,4'-biphenyltetracarboxylic acid is specifically as follows: for example, 100g of crude 3,3',4,4'-biphenyltetracarboxylic acid is added, a second reduced pressure sublimation is performed, and 5-10g of the initial fraction is collected (discarded); then the sublimation condenser is switched to continue collecting 70-80g of the interrupted fraction; the remaining fraction is treated as hazardous waste.

[0050] In the present invention, the mass percentage of the refined 3,3',4,4'-biphenyltetracarboxylic dianhydride is ≥99.9%.

[0051] The following is a detailed description of the method for treating mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid provided by the present invention in conjunction with the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] 100 g of dry mixed solid waste produced from the production of 3,3',4,4'-biphenyltetracarboxylic acid was taken. Testing showed that the dry mixed solid waste included the following substances by mass percentage: 63.5% of 3,3',4,4'-biphenyltetracarboxylic acid, 35.1% of phthalic acid, and 1.4% of chlorophthalic acid.

[0054] 100 g of dry mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimation kettle, the vacuum pump was turned on, the vacuum degree was controlled at 3.5 mmHg, the temperature was raised to 120°C for sublimation, and the temperature was lowered after sublimation to obtain 65.3 g of kettle residue, which was crushed to a particle size of ≤3 mm to obtain pretreated solid waste; the pretreated solid waste was added to 135 g of a 20% by mass sodium hydroxide solution, the temperature was raised to 95°C, and after keeping the temperature for 1 hour, the insoluble matter was removed by filtration to obtain an alkaline solution; the pH of the alkaline solution was adjusted to 0.95 using 30% by mass hydrochloric acid, the temperature was lowered to 80°C, hot filtered, and dried to obtain 61.5 g of crude 3,3',4,4'-biphenyltetracarboxylic acid. The mass content of 3,3',4,4'-biphenyltetracarboxylic acid was determined to be 99.52%.

[0055] 61.5 g of crude 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimator, the vacuum pump was turned on, the vacuum degree was controlled at 0.8 mmHg, the temperature was raised to 230°C for sublimation, 4.2 g of the front fraction was collected (discarded), and then the product was collected. After the sublimation was completed, the temperature was lowered to obtain 48.3 g of white refined 3,3',4,4'-biphenyltetracarboxylic dianhydride. After testing, the mass content of 3,3',4,4'-biphenyltetracarboxylic dianhydride was 99.91%, which met the product quality standards in T / CIEP 010-2022.

[0056] Example 2

[0057] 100 g of dry mixed solid waste produced from the production of 3,3',4,4'-biphenyltetracarboxylic acid was taken. Testing showed that the dry mixed solid waste included the following substances by mass percentage: 63.5% of 3,3',4,4'-biphenyltetracarboxylic acid, 35.1% of phthalic acid, and 1.4% of chlorophthalic acid.

[0058] 100 g of dry mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimation kettle, the vacuum pump was turned on, the vacuum degree was controlled at 3 mmHg, the temperature was raised to 120°C for sublimation, and the temperature was lowered after sublimation to obtain 67.3 g of kettle residue, which was crushed to a particle size of ≤3 mm to obtain pretreated solid waste; the pretreated solid waste was added to 145 g of a sodium hydroxide solution with a mass concentration of 20%, the temperature was raised to 100°C, kept warm for 1 hour, and the insoluble matter was removed by filtration to obtain an alkaline solution; the pH of the alkaline solution was adjusted to 1.22 using hydrochloric acid with a mass concentration of 30%, the temperature was lowered to 75°C, hot filtered, and dried to obtain 62.4 g of crude 3,3',4,4'-biphenyltetracarboxylic acid. The mass content of 3,3',4,4'-biphenyltetracarboxylic acid was found to be 99.50%.

[0059] 62.3 g of crude 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimator, the vacuum pump was turned on, the vacuum degree was controlled at 0.8 mmHg, the temperature was raised to 230°C for sublimation, 5.1 g of the front fraction was collected (discarded), and then the product was collected. After the sublimation was completed, the temperature was lowered to obtain 47.6 g of white refined 3,3',4,4'-biphenyltetracarboxylic dianhydride. After testing, the mass content of 3,3',4,4'-biphenyltetracarboxylic dianhydride was 99.92%, which met the product quality standards in T / CIEP 010-2022.

[0060] Example 3

[0061] 100 g of dry mixed solid waste produced from the production of 3,3',4,4'-biphenyltetracarboxylic acid was taken. Testing showed that the dry mixed solid waste included the following substances by mass percentage: 63.5% of 3,3',4,4'-biphenyltetracarboxylic acid, 35.1% of phthalic acid, and 1.4% of chlorophthalic acid.

[0062] 100 g of dry mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimation kettle, the vacuum pump was turned on, the vacuum degree was controlled at 3 mmHg, the temperature was raised to 110°C for sublimation, and the temperature was lowered after sublimation to obtain 64.3 g of kettle residue, which was crushed to a particle size of ≤3 mm to obtain pretreated solid waste; the pretreated solid waste was added to 108 g of a 30% sodium hydroxide solution, the temperature was raised to 95°C, kept warm for 1 hour, and the insoluble matter was removed by filtration to obtain an alkaline solution; the pH of the alkaline solution was adjusted to 0.68 using 30% hydrochloric acid, the temperature was lowered to 70°C, hot filtered, and dried to obtain 60.9 g of crude 3,3',4,4'-biphenyltetracarboxylic acid; the mass content of 3,3',4,4'-biphenyltetracarboxylic acid was found to be 99.50%.

[0063] 60.5 g of crude 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimator, the vacuum pump was turned on, the vacuum degree was controlled at 0.8 mmHg, the temperature was raised to 235°C for sublimation, 4.5 g of the front fraction was collected (discarded), and then the product was collected. After the sublimation was completed, the temperature was lowered to obtain 44.9 g of white refined 3,3',4,4'-biphenyltetracarboxylic dianhydride. After testing, the mass content of 3,3',4,4'-biphenyltetracarboxylic dianhydride was 99.93%, which met the product quality standards in T / CIEP 010-2022.

[0064] Comparative Example 1

[0065] 100 g of dry mixed solid waste produced from the production of 3,3',4,4'-biphenyltetracarboxylic acid was taken. Testing showed that the dry mixed solid waste included the following substances by mass percentage: 63.5% of 3,3',4,4'-biphenyltetracarboxylic acid, 35.1% of phthalic acid, and 1.4% of chlorophthalic acid.

[0066] 100g of dry mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimation kettle. The vacuum pump was turned on, the vacuum was controlled at 3.5mmHg, and the temperature was raised to 120°C for sublimation. After sublimation, the temperature was cooled to obtain 65.3g of kettle residue. The 65.3g kettle residue continued to sublime, the vacuum was controlled at 0.8mmHg, and the temperature was raised to 220°C for sublimation. 4.8g of the front fraction was collected, and then product collection was started. After sublimation, the temperature was cooled to obtain 51.3g of white 3,3',4,4'-biphenyltetracarboxylic dianhydride. Testing showed that the mass content of 3,3',4,4'-biphenyltetracarboxylic dianhydride was 98.9%, which does not meet the product quality standard in T / CIEP 010-2022.

[0067] Comparative Example 2

[0068] 100 g of dry mixed solid waste produced from the production of 3,3',4,4'-biphenyltetracarboxylic acid was taken. Testing showed that the dry mixed solid waste included the following substances by mass percentage: 63.5% of 3,3',4,4'-biphenyltetracarboxylic acid, 35.1% of phthalic acid, and 1.4% of chlorophthalic acid.

[0069] 100 g of dry mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid was added to 250 g of a 20% sodium hydroxide solution, the temperature was raised to 95°C, kept warm for 1 hour, and the insoluble matter was removed by filtration to obtain an alkaline solution; the pH of the alkaline solution was adjusted to 0.95 using 30% hydrochloric acid, the temperature was lowered to 80°C, filtered, and dried to obtain 94.1 g of crude 3,3',4,4'-biphenyltetracarboxylic acid. After testing, the mass content of 3,3',4,4'-biphenyltetracarboxylic acid was 67.1%.

[0070] 94 g of crude 3,3',4,4'-biphenyltetracarboxylic acid was placed in a sublimator, the vacuum pump was turned on, the vacuum degree was controlled at 0.8 mmHg, the temperature was raised to 220°C for sublimation, 4.2 g of the front fraction was collected (discarded), and then the product was collected. After the sublimation was completed, the temperature was lowered to obtain 74.1 g of white 3,3',4,4'-biphenyltetracarboxylic dianhydride. After testing, the mass content of 3,3',4,4'-biphenyltetracarboxylic dianhydride was 72.1%, which did not meet the product quality standard in T / CIEP 010-2022.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for treating mixed solid waste from the production of 3,3',4,4'-biphenyltetracarboxylic acid, characterized in that: The following steps are involved: Subliming the mixed solid waste produced by 3,3',4,4'-biphenyltetracarboxylic acid under first reduced pressure to obtain pretreated solid waste; alkali-dissolving the pretreated solid waste to remove alkali-insoluble matter to obtain an alkaline solution; The pH value of the alkaline solution is adjusted to acidic, and hot filtration is performed to obtain a crude product of 3,3',4,4'-biphenyltetracarboxylic acid; The crude 3,3',4,4'-biphenyltetracarboxylic acid product is subjected to a second reduced pressure sublimation, the initial fraction is discarded, and the middle fraction is collected to obtain refined 3,3',4,4'-biphenyltetracarboxylic dianhydride; The mass of the initial fraction is 5 to 10% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid; The mass of the middle fraction is 70-80% of the weight of 3,3',4,4'-biphenyltetracarboxylic acid; The temperature of the first reduced pressure sublimation is 110-120° C., and the vacuum degree is 3-5 mmHg; The temperature of the second reduced-pressure sublimation is 230-240° C., and the vacuum degree is ≤1 mmHg.

2. The processing method according to claim 1, characterized in that The pH value of the alkaline solution is 12-14, and the temperature is 80-105°C.

3. The processing method according to claim 1 or 2, characterized in that The mass concentration of the alkali solution used in the alkali dissolution is 20-30%.

4. The processing method according to claim 1, characterized in that The method of removing the alkali-insoluble matter is solid-liquid separation.

5. The processing method according to claim 1, characterized in that The acidic pH value is 0.5 to 1.

5.

6. The processing method according to claim 1, characterized in that The temperature of the hot filtration is 70-80°C.