A wet oxidation catalyst, its preparation method and application

Abstract

The present invention discloses a wet oxidation catalyst, a preparation method thereof and an application thereof, belonging to the field of wastewater treatment. Using styrene-based porous microsphere resin as a raw material, under the action of a catalyst, a Knoevenagel reaction occurs between polyfunctional aldehyde-based small molecules and polyfunctional cyano-based small molecules through an adsorption polymerization method, and a conjugated carbon organic porous polymer is coated on the surface of the styrene-based porous microsphere resin to form a porous microsphere resin coated with conjugated carbon; then a sulfonation reaction is carried out to obtain a sulfonic acid group-modified conjugated carbon-coated porous microsphere resin; then it is impregnated in a noble metal salt solution to form a resin-metal complex, and then filtered, washed and dried to obtain the wet oxidation catalyst. This catalyst can be used for the catalytic oxidation degradation of organic wastewater. Taking bisphenol A as a simulated organic wastewater, the removal rate of bisphenol A is over 95% after treatment.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater treatment, and particularly relates to a wet oxidation catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] In practical applications of the wet catalytic oxidation technology, sewage is pumped into a heat exchanger by a high-pressure pump through a storage tank, exchanges heat with the high-temperature oxidized liquid after the reaction, and enters a reactor after the temperature rises to be close to the reaction temperature. The oxygen required for the reaction is pumped into the reactor by a compressor. In the reactor, the organic matter in the sewage reacts exothermically with the oxygen. At a relatively high temperature, the organic matter in the sewage is oxidized into carbon dioxide and water, or intermediate products such as small-molecule organic acids. After the reaction, the gas-liquid mixture is separated by a separator, and the liquid phase preheats the feed through a heat exchanger to recover heat energy. The high-temperature and high-pressure tail gas first generates steam through a reboiler or preheats the boiler feed water through a heat exchanger. Its condensed water is separated by the separator and then pumped back into the reactor through a circulation pump. The separated high-pressure tail gas can generate mechanical energy or electrical energy. The wet catalytic oxidation technology has the advantages of high purification efficiency, less secondary pollution, wide treatment range, high economic benefits, etc., and is one of the frontier technologies in the field of treatment technologies for refractory industrial wastewater.

[0003] At present, the wet oxidation catalysts are generally activated carbon-based, metal oxide-based, and there is still a need for further research on the use of polymer-based catalysts for wet oxidation catalysts. The wet oxidation catalyst of the polymer resin composite modification type combines the functions of enrichment and catalysis, and has the prospect of industrial development and application potential. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies and defects in the background art, and provide a wet oxidation catalyst, a preparation method thereof, and an application thereof, with a high removal rate of organic pollutants.

[0005] To solve the above technical problem, the technical solution proposed by the present invention is as follows:

[0006] A preparation method of a wet oxidation catalyst, comprising the following steps:

[0007] (1) Using a styrene-based porous microsphere resin as a raw material, under the action of a catalyst, a Knoevenagel reaction occurs between a polyfunctional aldehyde group small molecule and a polyfunctional cyano group small molecule through an adsorption polymerization method, and a conjugated carbon organic porous polymer is coated on the surface of the styrene-based porous microsphere resin to form a conjugated carbon-coated porous microsphere resin;

[0008] (2) Subjecting the conjugated carbon-coated porous microsphere resin to a sulfonation reaction to obtain a sulfonic acid group-modified conjugated carbon-coated porous microsphere resin;

[0009] (3) Immerse the sulfonic acid group-modified conjugated carbon-coated porous microsphere resin in a noble metal salt solution to form a resin-metal complex, and then filter, wash, and dry to obtain the wet oxidation catalyst.

[0010] As a further improvement, the polyfunctional aldehyde-based small molecule in step (1) is one or any combination of terephthalaldehyde, biphenyl dialdehyde, and benzene-1,3,5-tricarbaldehyde.

[0011] As a further improvement, the polyfunctional cyano-based small molecule in step (1) is p-phenylene diacetonitrile and / or biphenyl diacetonitrile.

[0012] As a further improvement, the catalyst in step (1) is tetrabutylammonium hydroxide.

[0013] As a further improvement, the reaction temperature in step (1) is 100 - 120 °C.

[0014] As a further improvement, the noble metal salt in step (3) is one or any combination of ruthenium chloride, iridium chloride, chloroauric acid, and platinum chloride.

[0015] As a further improvement, the dosage of the noble metal salt in step (3) is 1 - 5% of the mass of the sulfonic acid group-modified conjugated carbon-coated porous microsphere resin.

[0016] As a further improvement, the impregnation temperature in step (3) is 60 - 80 °C.

[0017] A wet oxidation catalyst provided by the present invention is prepared by using the described method.

[0018] The present invention also provides an application of the described wet oxidation catalyst in the degradation of organic wastewater.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The present invention uses styrene-based porous microsphere resin as a raw material. First, through adsorption polymerization, a Knoevenagel reaction occurs between polyfunctional aldehyde-based small molecules and polyfunctional cyano-based small molecules to coat a conjugated carbon organic porous polymer on the surface of the porous microsphere resin, forming a porous microsphere resin coated with conjugated carbon. Medium-polarity and polar resins have good adsorption capacity for organic substances, which can play an enrichment role for organic substances and increase the contact efficiency between oxidation species and organic pollutants. The porous conjugated carbon has a structure and properties similar to graphene, and its introduction can better stimulate hydrogen peroxide to rapidly generate a large amount of hydroxyl radicals. Then, the porous microsphere resin coated with conjugated carbon is subjected to a sulfonation reaction to obtain a porous microsphere resin coated with conjugated carbon modified with sulfonic acid groups. The introduction of sulfonic acid groups can increase the adsorption sites of noble metals and enhance the loading capacity of noble metals. Then, the porous microsphere resin coated with conjugated carbon modified with sulfonic acid groups is impregnated in a noble metal solution to form a resin-metal complex. The introduction of noble metals can further stimulate the activity of hydroxyl radicals and accelerate the oxidative decomposition of organic substances.

[0021] Load this catalyst into a high-pressure reactor, and it can be used for the catalytic oxidation and degradation of organic wastewater by controlling the temperature and the addition of oxidants. Using bisphenol A as a simulated organic wastewater, the removal rate of bisphenol A is over 95% after treatment. Specific embodiments

[0022] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in combination with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0024] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0025] In some embodiments of the present invention, a preparation method of a wet oxidation catalyst includes the following steps:

[0026] (1) Using styrene-based porous microsphere resin as a raw material, through adsorption polymerization, a Knoevenagel reaction (Knoevenagel reaction) occurs between polyfunctional aldehyde-based small molecules and polyfunctional cyano-based small molecules under the action of a catalyst to coat a conjugated carbon organic porous polymer on the surface of the porous microsphere resin, forming a porous microsphere resin coated with conjugated carbon.

[0027] In some embodiments, the styrene-based porous microsphere resin can be a polystyrene porous microsphere resin, which can be polar or moderately polar, with a particle size of 0.5 - 5 mm. Before use, it is dried at a temperature of 80 - 120 °C.

[0028] In some embodiments, the polyfunctional aldehyde-based small molecule can be one or several of terephthalaldehyde, biphenyldialdehyde, and benzene-1,3,5-tricarbaldehyde. The dosage of the polyfunctional aldehyde-based small molecule is 1 - 5% of the mass of the porous microsphere resin.

[0029] In some embodiments, the polyfunctional cyano-based small molecule can be one or a mixture of two of terephthalonitrile and biphenyldiacetonitrile. The dosage of the polyfunctional cyano-based small molecule is 1 - 5% of the mass of the porous microsphere resin.

[0030] In some embodiments, the catalyst used is tetrabutylammonium hydroxide, and the dosage of the catalyst is 0.1 - 0.5% of the mass of the porous microsphere resin. The reaction solvent is mesitylene, and its dosage is 2 - 4 times the mass of the porous microsphere resin. The reaction temperature is 100 - 120 °C, and the reaction time is 12 - 24 h.

[0031] (2) The porous microsphere resin coated with conjugated carbon is subjected to a sulfonation reaction to obtain a sulfonic acid group-modified conjugated carbon-coated porous microsphere resin.

[0032] In some embodiments, the sulfonation reagent is a sulfuric acid solution with a mass concentration of 30 - 60%. The sulfonation reaction temperature is 80 - 100 °C, and the sulfonation time is 6 - 8 h.

[0033] (3) The sulfonic acid group-modified conjugated carbon-coated porous microsphere resin is impregnated in a noble metal salt solution to form a resin-metal complex, and then it is filtered, washed, and dried to obtain the wet oxidation catalyst.

[0034] In some embodiments, the noble metal salt can be one or several of ruthenium chloride, iridium chloride, chloroauric acid, and platinum chloride. The dosage of the noble metal salt is 1 - 5% of the mass of the sulfonic acid group-modified conjugated carbon-coated porous microsphere resin, the mass concentration of the metal salt aqueous solution is 5 - 10%, the impregnation time is 4 - 8 h, and the impregnation temperature is 60 - 80 °C.

[0035] In some embodiments, the washing solvents for the resin-metal complex are methanol and toluene in sequence. The vacuum drying temperature of the complex is 80 - 120 °C, and the drying time is 12 h.

[0036] When in use, the catalyst is directly loaded into a wet oxidation reactor for the treatment of organic wastewater containing bisphenol A, chlorobenzene, nitrobenzene, etc. Hydrogen peroxide can be used as the oxidant, and the addition amount of hydrogen peroxide is 0.1 - 0.2% of the volume of the wastewater. The wet oxidation temperature is 120 - 160 °C.

[0037] In the wet oxidation catalytic system, a large amount of strongly oxidizing active species of hydroxyl radicals will be catalyzed to generate from hydrogen peroxide. The hydroxyl radicals first attack the benzene ring structure of bisphenol A to break the bond of bisphenol A and generate organic small molecules, and the organic small molecules are further oxidized by the hydroxyl radicals into carbon dioxide and water. If only hydrogen peroxide is added without any catalyst, the degradation rate of bisphenol A is less than 20%.

[0038] In the following examples, the medium-polarity styrene-based porous microsphere resin uses the D113 macroporous weakly acidic cation exchange resin of Langfang Sunnat Chemical Co., Ltd., and the polar styrene-based porous microsphere resin uses the D001 macroporous strongly acidic cation exchange resin of Langfang Sunnat Chemical Co., Ltd.

[0039] Example 1

[0040] Place 1 kg of medium-polarity styrene-based porous microsphere resin with a particle size of 2 mm in a 100 °C forced-air drying oven for 12 h for drying treatment and reserve. Additionally, dissolve 10 g of terephthalaldehyde, 15 g of terephthalonitrile, and 1 g of tetrabutylammonium hydroxide in 2 kg of mesitylene to form a solution. Pour the dried resin into the above solution, heat up to 120 °C and react for 24 h. After the reaction is completed, filter to obtain conjugated carbon-coated porous microsphere resin. Pour the obtained resin into 50% sulfuric acid solution, heat up to 100 °C and react for 8 h, and filter to obtain sulfonic acid group-modified conjugated carbon-coated porous microsphere resin. Take 10 g of ruthenium chloride and make it into a 5% aqueous solution and heat up to 60 °C. Pour the sulfonic acid group-modified conjugated carbon-coated porous microsphere resin into the metal salt solution and soak for 8 h, then filter off the excess solution and wash successively with methanol and toluene, and dry the washed composite at 100 °C for 12 h to obtain the wet oxidation catalyst.

[0041] Load the catalyst into a wet reaction kettle, pour 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L into the reaction kettle, add 2 mL of hydrogen peroxide, and react at 150 °C for 20 min. After the reaction is completed, the concentration of bisphenol A is 1.4 mg / L, and the removal rate is 98.6%.

[0042] Example 2

[0043] 1 kg of polar styrene-based porous microsphere resin with a particle size of 2 mm was placed in a 100 °C forced-air drying oven for 12 h for drying treatment and reserved for use. Separately, 10 g of terephthalaldehyde, 15 g of terephthalonitrile, and 1 g of tetrabutylammonium hydroxide were dissolved in 2 kg of mesitylene to prepare a solution. The dried resin was poured into the above solution, and the temperature was raised to 120 °C for reaction for 24 h. After the reaction ended, filtration was carried out to obtain conjugated carbon-coated porous microsphere resin. The resin obtained above was poured into a 50% sulfuric acid solution, and the temperature was raised to 100 °C for reaction for 8 h. Filtration was carried out to obtain sulfonic acid group-modified conjugated carbon-coated porous microsphere resin. 10 g of ruthenium chloride was prepared into a 5% aqueous solution and the temperature was raised to 60 °C. The sulfonic acid group-modified conjugated carbon-coated porous microsphere resin was poured into the metal salt solution and soaked for 8 h, then the excess solution was filtered off and washed successively with methanol and toluene. The washed composite was dried at 100 °C for 12 h to obtain a wet oxidation catalyst.

[0044] The catalyst was loaded into a wet reaction kettle. 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L was poured into the reaction kettle, and 2 mL of hydrogen peroxide was added. The reaction was carried out at 150 °C for 20 min. After the reaction ended, the concentration of bisphenol A was 3.4 mg / L, and the removal rate was 96.6%.

[0045] Example 3

[0046] 1 kg of medium-polarity styrene-based porous microsphere resin with a particle size of 2 mm was placed in a 100 °C forced-air drying oven for 12 h for drying treatment and reserved for use. Separately, 10 g of biphenyl dialdehyde, 15 g of terephthalonitrile, and 1 g of tetrabutylammonium hydroxide were dissolved in 2 kg of mesitylene to prepare a solution. The dried resin was poured into the above solution, and the temperature was raised to 120 °C for reaction for 24 h. After the reaction ended, filtration was carried out to obtain conjugated carbon-coated porous microsphere resin. The resin obtained above was poured into a 50% sulfuric acid solution, and the temperature was raised to 100 °C for reaction for 8 h. Filtration was carried out to obtain sulfonic acid group-modified conjugated carbon-coated porous microsphere resin. 10 g of ruthenium chloride was prepared into a 5% aqueous solution and the temperature was raised to 60 °C. The sulfonic acid group-modified conjugated carbon-coated porous microsphere resin was poured into the metal salt solution and soaked for 8 h, then the excess solution was filtered off and washed successively with methanol and toluene. The washed composite was dried at 100 °C for 12 h to obtain a wet oxidation catalyst.

[0047] The catalyst was loaded into a wet reaction kettle. 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L was poured into the reaction kettle, and 2 mL of hydrogen peroxide was added. The reaction was carried out at 150 °C for 20 min. After the reaction ended, the concentration of bisphenol A was 2.6 mg / L, and the removal rate was 97.4%.

[0048] Example 4

[0049] Put 1 kg of medium-polarity styrene-based porous microsphere resin with a particle size of 2 mm in a 100 °C forced-air drying oven for 12 h for drying treatment and reserve it for use. Separately, dissolve 10 g of terephthalaldehyde, 15 g of biphenyldiacetonitrile, and 1 g of tetrabutylammonium hydroxide in 2 kg of mesitylene to prepare a solution. Pour the dried resin into the above solution, raise the temperature to 120 °C and react for 24 h. After the reaction is completed, filter to obtain conjugated carbon-coated porous microsphere resin. Pour the resin obtained above into 50% sulfuric acid solution, raise the temperature to 100 °C and react for 8 h, and filter to obtain sulfonic acid group-modified conjugated carbon-coated porous microsphere resin. Weigh 10 g of ruthenium chloride to prepare a 5% aqueous solution and raise the temperature to 60 °C. Pour the sulfonic acid group-modified conjugated carbon-coated porous microsphere resin into the metal salt solution and soak for 8 h, then filter off the excess solution and wash successively with methanol and toluene. Dry the washed composite at 100 °C for 12 h to obtain the wet oxidation catalyst.

[0050] Load the catalyst into a wet reaction kettle. Pour 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L into the reaction kettle, and add 2 mL of hydrogen peroxide. React at 150 °C for 20 min. After the reaction is completed, the concentration of bisphenol A is 2.9 mg / L, and the removal rate is 97.1%.

[0051] Comparative Example 1

[0052] Put 1 kg of medium-polarity styrene-based porous microsphere resin with a particle size of 2 mm in a 100 °C forced-air drying oven for 12 h for drying treatment and reserve it for use. Without conjugated carbon coating, directly pour it into 50% sulfuric acid solution, raise the temperature to 100 °C and react for 8 h, and filter to obtain sulfonic acid group-modified porous microsphere resin. Weigh 10 g of ruthenium chloride to prepare a 5% aqueous solution and raise the temperature to 60 °C. Pour the sulfonic acid group-modified porous microsphere resin into the metal salt solution and soak for 8 h, then filter off the excess solution and wash successively with methanol and toluene. Dry the washed composite at 100 °C for 12 h to obtain the wet oxidation catalyst.

[0053] Load the catalyst into a wet reaction kettle. Pour 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L into the reaction kettle, and add 2 mL of hydrogen peroxide. React at 150 °C for 20 min. After the reaction is completed, the concentration of bisphenol A is 42.1 mg / L, and the removal rate is 57.9%.

[0054] Comparative Example 2

[0055] Put 1 kg of medium-polarity styrene-based porous microsphere resin with a particle size of 2 mm in a blast drying oven at 100 °C for 12 h for drying treatment and reserve it. Separately, dissolve 10 g of terephthalaldehyde, 15 g of terephthalonitrile, and 1 g of tetrabutylammonium hydroxide in 2 kg of mesitylene to form a solution. Pour the dried resin into the above solution, heat up to 120 °C and react for 24 h. After the reaction is completed, filter to obtain porous microsphere resin coated with conjugated carbon. Without undergoing sulfonation reaction, directly pour it into a metal salt solution and soak for 8 h, then filter off the excess solution and wash successively with methanol and toluene. Dry the washed composite at 100 °C for 12 h to obtain a wet oxidation catalyst.

[0056] Load the catalyst into a wet reaction kettle, pour 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L into the reaction kettle, add 2 mL of hydrogen peroxide, react at 150 °C for 20 min. After the reaction is completed, the concentration of bisphenol A is 32.9 mg / L, and the removal rate is 67.1%.

[0057] Comparative Example 3

[0058] Put 1 kg of medium-polarity styrene-based porous microsphere resin with a particle size of 2 mm in a blast drying oven at 100 °C for 12 h for drying treatment and reserve it. Separately, dissolve 10 g of terephthalaldehyde, 15 g of terephthalonitrile, and 1 g of tetrabutylammonium hydroxide in 2 kg of mesitylene to form a solution. Pour the dried resin into the above solution, heat up to 120 °C and react for 24 h. After the reaction is completed, filter to obtain porous microsphere resin coated with conjugated carbon. Pour the resin obtained above into 50% sulfuric acid solution, heat up to 100 °C and react for 8 h, and filter to obtain sulfonic acid group-modified conjugated carbon-coated porous microsphere resin.

[0059] Directly load the resin obtained in this step into a wet reaction kettle, pour 2 L of bisphenol A aqueous solution with a concentration of 100.0 mg / L into the reaction kettle, add 2 mL of hydrogen peroxide, react at 150 °C for 20 min. After the reaction is completed, the concentration of bisphenol A is 53.2 mg / L, and the removal rate is 46.8%.

[0060] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Therefore, all contents that do not depart from the technical solution of the present invention, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a wet oxidation catalyst, characterized in that: The steps include: (1) Using styrene-based porous microsphere resin as raw material, multifunctional aldehyde small molecules and multifunctional cyano small molecules undergo Knoevenagel reaction by adsorption polymerization under the action of a catalyst, and a layer of conjugated carbon organic porous polymer is coated on the surface of the styrene-based porous microsphere resin to form a conjugated carbon-coated porous microsphere resin; The multifunctional aldehyde small molecule is one or both of terephthalaldehyde and biphenyl dicarboxaldehyde; the multifunctional cyano small molecule is terephthalonitrile and / or biphenyl diacetonitrile; (2) subjecting the conjugated carbon-coated porous microsphere resin to a sulfonation reaction to obtain a sulfonic acid group-modified conjugated carbon-coated porous microsphere resin; (3) The sulfonic acid group-modified conjugated carbon-coated porous microsphere resin is impregnated in a noble metal salt solution to form a resin-metal complex, which is then filtered, washed, and dried to obtain the wet oxidation catalyst.

2. The method for preparing a wet oxidation catalyst according to claim 1, characterized in that: The catalyst in step (1) is tetrabutylammonium hydroxide.

3. The method for preparing a wet oxidation catalyst according to claim 1, characterized in that: The reaction temperature of step (1) is 100-120°C.

4. The method for preparing a wet oxidation catalyst according to claim 1, characterized in that: The noble metal salt in step (3) is one or any combination of ruthenium chloride, iridium chloride, chloroauric acid, and platinum chloride.

5. The method for preparing a wet oxidation catalyst according to claim 1 or 4, characterized in that: The amount of the noble metal salt used in step (3) is 1-5% of the mass of the sulfonic acid group-modified conjugated carbon-coated porous microsphere resin.

6. The method for preparing a wet oxidation catalyst according to claim 1 or 4, characterized in that: The immersion temperature in step (3) is 60-80°C.

7. A wet oxidation catalyst, characterized in that: It is prepared by the method described in any one of claims 1 to 6.

8. Use of the wet oxidation catalyst according to claim 7 in degrading organic wastewater.