A catalyst for treating high-salt high-concentration organic wastewater and a preparation method thereof

Abstract

The present invention discloses a catalyst for treating high-salt high-concentration organic wastewater and a preparation method thereof, belonging to the technical fields of noble metal catalysts and sewage treatment. The steps of the preparation method include: performing surface functionalization treatment on the TiO2 carrier material to obtain a siliconophilic TiO2 carrier material; introducing a ruthenium complex into the S-1 zeolite precursor solution to obtain an S-1 zeolite precursor solution with in-situ confined ruthenium; immersing the siliconophilic TiO2 carrier material in the S-1 zeolite precursor solution with in-situ confined ruthenium, performing hydrothermal crystallization, taking out the TiO2 carrier material, drying and then calcining to prepare a catalyst for treating high-salt high-concentration organic wastewater. Through the confinement design of ruthenium, the present invention greatly reduces the noble metal dosage and improves the economy of the catalyst. The combination of the hydrophobic structure of the S-1 zeolite and the high mechanical strength of TiO2 enables the catalyst to stably operate for a long time in the environment of high-salt high-concentration organic wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical fields of noble metal catalysts and sewage treatment, and particularly relates to a catalyst for treating high-salt high-concentration organic wastewater and a preparation method thereof. Background Art

[0002] The catalytic wet air oxidation (CWAO) technology is an important method for treating high-concentration organic wastewater, which can convert refractory organic matter into non-toxic small-molecule substances through oxidation under high-temperature and high-pressure conditions. However, there are still significant problems with existing catalysts in practical applications. The current mainstream carrier is titanium oxide (TiO2), and the catalytic activity is often enhanced by loading noble metals (such as Ru, Pt, Pd). However, such catalysts generally face the following challenges: (1) The reaction usually takes place under high-temperature and high-pressure conditions, and noble metal particles are prone to loss due to migration, aggregation or dissolution, resulting in reduced activity and insufficient stability; (2) The traditional loading methods of noble metals are difficult to effectively reduce the metal usage; (3) In saline wastewater, Cl - - ions have a serious poisoning effect on noble metal centers, significantly weakening the salt resistance of the catalyst; (4) The problem of carbon deposition is widespread. Some reaction intermediates (such as phenol, quinones) are prone to form a carbon deposition layer on the catalyst surface, covering the active sites and further accelerating the inactivation of the catalyst. Summary of the Invention

[0003] In view of the above problems, the present invention provides a catalyst for treating high-salt high-concentration organic wastewater and a preparation method thereof. With S-1 zeolite confining noble metal ruthenium as the core and combined with a strip-shaped titanium oxide carrier, the uniform combination of the zeolite and the carrier is achieved through a hydrothermal in-situ growth technique. Different from the traditional ruthenium loading method, the present invention directly introduces a ruthenium source during the synthesis of S-1 zeolite, enabling ruthenium to be embedded in the microporous structure of the zeolite in a confined manner, significantly improving the dispersion of noble metals and reducing the usage of active metals. At the same time, S-1 zeolite can selectively adsorb non-polar organic pollutants, effectively alleviating the carbon deposition problem; its framework structure provides protection for ruthenium particles, greatly reducing the risk of metal loss in a saline environment. In addition, through a hydrothermal crystallization process, the S-1 zeolite confining ruthenium is uniformly grown on the surface of the titanium oxide carrier, avoiding the problem of uneven zeolite coverage that may exist in the traditional coating process, and further improving the mechanical stability and thermal stability of the catalyst. Through the technological innovation of confining noble metals in zeolites and optimizing the carrier combination method, the present invention provides an efficient, low-cost, highly salt-resistant and excellent carbon deposition-resistant catalyst solution for the treatment of high-concentration organic wastewater by catalytic wet air oxidation.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] One of the technical solutions of the present invention: provides a preparation method of a catalyst for treating high-concentration organic wastewater containing salt, comprising the following steps:

[0006] Perform surface functionalization treatment on the TiO2 support material to obtain a siliconophilic TiO2 support material;

[0007] Introduce a ruthenium complex into the S-1 zeolite precursor solution to obtain an S-1 zeolite precursor solution with in-situ confined ruthenium;

[0008] Immerse the siliconophilic TiO2 support material in the S-1 zeolite precursor solution with in-situ confined ruthenium, perform hydrothermal crystallization, take out the siliconophilic TiO2 support material, dry it and then calcine it to prepare a catalyst for treating high-concentration organic wastewater containing salt.

[0009] The present invention selects TiO2 as the support material because TiO2 has strong chemical and thermal stability, can adapt to complex reaction environments, has low cost and is environmentally friendly, and is suitable for large-scale industrial applications; using TiO2 as the support can make the active component, the S-1 zeolite with confined ruthenium, have good dispersion, which is conducive to the catalytic reaction.

[0010] Preferably, the TiO2 support material is in strip shape.

[0011] The strip-shaped TiO2 support material can endow the prepared catalyst with a larger specific surface area.

[0012] Preferably, the TiO2 support material is pre-treated on the surface before the functionalization treatment to remove water and organic substances on the surface of the TiO2 support material.

[0013] Preferably, the surface functionalization treatment is to immerse the TiO2 support material in a silane coupling agent solution, stir it and then dry it to complete the surface functionalization treatment.

[0014] More preferably, the concentration of the silane coupling agent in the silane coupling agent solution is 1-3 wt.%, and the silane coupling agent is γ-aminopropyltriethoxysilane (APTES).

[0015] Preferably, the ruthenium complex is prepared by adding a complexing agent to an aqueous solution containing Ru 3+ and.

[0016] Optionally, the Ru 3+ is provided by a soluble ruthenium salt, and the soluble ruthenium salt can be selected from at least one of ruthenium chloride (RuCl3), ruthenium nitrate (Ru(NO3)3) and ruthenium acetylacetonate (Ru(acac)3); the complexing agent can be selected from at least one of ethylenediamine and citric acid.

[0017] Optionally, the silicon source of the S-1 molecular sieve precursor solution is tetraethyl orthosilicate, and the template agent is tetrapropylammonium hydroxide.

[0018] Preferably, the solid-liquid ratio of the siliconophilic TiO2 support material to the S-1 molecular sieve precursor solution in-situ confining ruthenium is 1 g: 10 - 30 mL.

[0019] Preferably, the temperature of the hydrothermal crystallization is 150 - 180 °C, and the time is 24 - 72 h.

[0020] Preferably, the temperature of the calcination is 400 - 600 °C.

[0021] The second technical solution of the present invention: Provide a catalyst for treating high-salt high-concentration organic wastewater prepared by the preparation method of the catalyst for treating high-salt high-concentration organic wastewater according to the above.

[0022] The third technical solution of the present invention: Provide an application of the above catalyst for treating high-salt high-concentration organic wastewater in wet catalytic oxidation of high-salt, high-concentration organic wastewater, wherein the COD concentration in the high-salt, high-concentration organic wastewater is 20000 - 50000 mg / L, and the salt content is 5 - 10 wt.%.

[0023] Preferably, the wet catalytic oxidation is carried out under the conditions of a temperature of 180 - 270 °C and an oxygen partial pressure of 1 - 3 MPa, and the concentration of the catalyst for treating high-salt high-concentration organic wastewater is 1 - 6 g / L.

[0024] The beneficial technical effects of the present invention are as follows:

[0025] By innovatively compounding the S-1 molecular sieve in-situ confining ruthenium with the TiO2 support, the present invention prepares a noble metal catalyst Ru@S-1 / TiO2 with excellent catalytic performance. The present invention significantly improves the activity, salt resistance and stability of the catalyst, especially in the application of wet catalytic oxidation (CWAO) to treat high-salt, high-concentration organic wastewater. Through the confinement design of ruthenium, the consumption of noble metals is greatly reduced, and the economy of the catalyst is improved. The combination of the hydrophobic structure of the S-1 molecular sieve and the high mechanical strength of TiO2 enables the catalyst to operate stably for a long time in the environment of high-salt, high-concentration organic wastewater. It solves the problem of performance degradation of traditional catalysts due to agglomeration, loss of active sites and carbonaceous deposition in a high-salt environment, and provides an efficient and sustainable solution for the treatment of complex industrial wastewater. Description of the Drawings

[0026] Figure 1 XRD pattern of the A-1 catalyst prepared in Example 1. Detailed Embodiments

[0027] The various exemplary embodiments of the present invention will be described in detail below. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and implementation manners of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0028] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Intermediate values within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, are also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention.

[0030] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0031] Example 1

[0032] Preparation of noble metal catalyst A-1:

[0033] Cleaning and functionalization of TiO2 surface: Clean strip-shaped TiO2 with 0.1M nitric acid solution and stir at room temperature for 2h. After washing, calcine at 350 °C for 2h to remove impurities. Immerse it in 1wt.% APTES solution, stir for 6h, then wash with deionized water and dry at 100 °C.

[0034] Preparation of S-1 molecular sieve precursor solution: Dissolve 0.02g of ruthenium chloride in 20mL of deionized water, add 0.4g of ethylenediamine as a complexing agent, and stir for 1h to form solution A. Add 8mL of tetraethyl orthosilicate (TEOS) to 10mL of deionized water, stir until complete hydrolysis to form a uniform silicon source solution, then add 13g of tetrapropylammonium hydroxide (TPAOH), and continuously stir for 2h to form solution B. Finally, slowly add solution A dropwise to solution B and continuously stir for 5h.

[0035] Catalyst preparation: Immerse the functionalized TiO2 (1g) in the prepared S-1 molecular sieve precursor solution (liquid-solid ratio 20mL:1g), and hydrothermally crystallize at 170 °C for 72h. After washing and drying, calcine at 550 °C for 6h to obtain the catalyst Ru@S-1 / TiO2 (A-1).

[0036] The XRD pattern of the A-1 catalyst prepared in Example 1 is shown in Figure 1 , and it can be seen from Figure 1 that the main substance on the surface of the shaped catalyst is S-1 zeolite, indicating that the zeolite has successfully adhered to the surface of the strip-shaped TiO2. The reason why the characteristic peak of Ru was not detected is mainly because its content is low and it is highly dispersed.

[0037] Treatment of high-concentration organic wastewater:

[0038] The performance of the catalyst was evaluated through batch reactions in a high-pressure autoclave. 0.15 g of the catalyst was mixed evenly with 50 mL of phenol solution and placed in a high-pressure autoclave. The COD concentration of the phenol solution was 20,000 mg / L, and the salt content was 5 wt.%. After the autoclave was sealed, 0.5 MPa of nitrogen was introduced into it, and then the gas was discharged through the exhaust port. This process of charging and discharging gas was repeated 4 times to exhaust the oxygen in the autoclave. The temperature of the autoclave was programmed to rise to 250 °C, and then 2 MPa of oxygen was introduced for wet catalytic oxidation, with a stirring speed of 500 r / min. After reacting for 3 h, the COD concentration of the treated solution was measured using a COD tester, and the COD removal efficiency of the catalyst was calculated. The results showed that the COD degradation efficiency of catalyst A-1 for high-concentration organic wastewater was 95%.

[0039] Example 2

[0040] Preparation of noble metal catalyst A-2:

[0041] Cleaning and functionalization of the TiO2 surface: The strip-shaped TiO2 was cleaned with 0.1 M hydrochloric acid solution and stirred at room temperature for 2 h. After washing, it was calcined at 400 °C for 2 h. It was immersed in a 2 wt.% APTES solution and stirred for 6 h, then washed and dried at 100 °C.

[0042] Preparation of the S-1 zeolite precursor solution: 0.015 g of ruthenium chloride was dissolved in 20 mL of deionized water, and 0.3 g of ethylenediamine was added as a complexing agent and stirred for 1 h to form solution A. 8 mL of TEOS was added to 10 mL of deionized water and stirred until complete hydrolysis to form a uniform silicon source solution, and then 15 g of TPAOH was added and stirred continuously for 2 h to form solution B. Finally, solution A was added dropwise to solution B and stirred continuously for 5 h.

[0043] Catalyst preparation: The functionalized TiO2 (1 g) was immersed in the prepared S-1 zeolite precursor solution (liquid-solid ratio 15 mL:1 g), and hydrothermally crystallized at 160 °C for 72 h. After washing and drying, it was calcined at 450 °C for 4 h to obtain the catalyst Ru@S-1 / TiO2 (A-2).

[0044] Treatment of high-concentration organic wastewater:

[0045] The performance of the catalyst was evaluated through batch reactions in a high-pressure autoclave. 0.4 g of the catalyst was mixed evenly with 100 mL of phenol solution and placed in the high-pressure autoclave. The COD concentration of the phenol solution was 30000 mg / L, and the salt content was 6 wt.%. After the autoclave was sealed, 0.5 MPa of nitrogen was introduced into it, and then the gas was discharged through the exhaust port. This process of charging and discharging the gas was repeated 4 times to completely remove the oxygen in the autoclave. The autoclave was heated up to 250 °C in a programmed manner, and then 2.5 MPa of oxygen was introduced to start wet catalytic oxidation, with a stirring speed of 600 r / min. After reacting for 2 h, the COD concentration of the treated solution was measured using a COD tester, and the COD removal efficiency of the catalyst was calculated. The results showed that the COD degradation efficiency of catalyst A-2 for high-concentration organic wastewater was 90.5%.

[0046] Example 3

[0047] Preparation of noble metal catalyst A-3:

[0048] Cleaning and functionalization of TiO2 surface: The strip-shaped TiO2 was cleaned with 0.1 M nitric acid solution and stirred at room temperature for 2 h. After washing, it was calcined at 375 °C for 2 h. It was immersed in 3 wt.% APTES solution and stirred for 6 h, and then washed and dried at 100 °C.

[0049] Preparation of S-1 molecular sieve precursor solution: 0.04 g of ruthenium acetylacetonate was dissolved in 20 mL of deionized water, and 0.3 g of ethylenediamine was added as a complexing agent and stirred for 1 h to form solution A. 8 mL of TEOS was added to 10 mL of deionized water and stirred until complete hydrolysis to form a uniform silicon source solution, and then 10 g of TPAOH was added and stirred continuously for 2 h to form solution B. Finally, solution A was added dropwise to solution B and stirred continuously for 5 h.

[0050] Catalyst preparation: The functionalized TiO2 (1 g) was immersed in the prepared S-1 molecular sieve precursor solution (liquid-solid ratio 10 mL:1 g), and hydrothermally crystallized at 150 °C for 48 h. After washing and drying, it was calcined at 550 °C for 5 h to obtain the catalyst Ru@S-1 / TiO2 (A-3).

[0051] Treatment of high-concentration organic wastewater

[0052] The performance of the catalyst was evaluated through batch reactions in a high-pressure reactor. 0.25 g of the catalyst was mixed evenly with 50 ml of phenol solution and placed in the high-pressure reactor. The COD concentration of the phenol solution was 40000 mg / L, and the salt content was 7 wt.%. After the reactor was sealed, 0.5 MPa of nitrogen was introduced into it, and then the exhaust port was opened to discharge the gas. This process of charging and discharging gas was repeated 4 times to completely remove the oxygen in the reactor. The reactor was heated up to 250 °C in a programmed manner, and then 3 MPa of oxygen was introduced for wet catalytic oxidation, with a stirring speed of 500 r / min. After reacting for 2 h, the COD concentration of the treated solution was measured using a COD tester, and the COD removal efficiency of the catalyst was calculated. The results showed that the COD degradation efficiency of catalyst A-3 for high-concentration organic wastewater was 92.4%.

[0053] Example 4

[0054] Preparation of noble metal catalyst A-1: The same as Example 1.

[0055] Treatment of high-concentration organic wastewater:

[0056] The performance of the catalyst was evaluated through batch reactions in a high-pressure reactor. 0.6 g of the catalyst was mixed evenly with 100 mL of phenol solution and placed in the high-pressure reactor. The COD concentration of the phenol solution was 50000 mg / L, and the salt content was 8 wt.%. After the reactor was sealed, 0.5 MPa of nitrogen was introduced into it, and then the exhaust port was opened to discharge the gas. This process of charging and discharging gas was repeated 4 times to completely remove the oxygen in the reactor. The reactor was heated up to 270 °C in a programmed manner, and then 3 MPa of oxygen was introduced for wet catalytic oxidation, with a stirring speed of 800 r / min. After reacting for 4 h, the COD concentration of the treated solution was measured using a COD tester, and the COD removal efficiency of the catalyst was calculated. The results showed that the COD degradation efficiency of catalyst A-1 for high-concentration organic wastewater was 98.3%. After 20 cycles of reaction, the COD degradation efficiency remained above 90%.

[0057] Example 5

[0058] Preparation of noble metal catalyst A-2: The same as Example 2.

[0059] Treatment of high-concentration organic wastewater:

[0060] The performance of the catalyst was evaluated by batch reaction in a high-pressure reactor. 0.2 g of the catalyst was mixed evenly with 100 mL of phenol solution and placed in the high-pressure reactor. The COD concentration of the phenol solution was 25,000 mg / L, and the salt content was 5 wt.%. After the reactor was sealed, 0.5 MPa of nitrogen was charged into it, and then the gas was discharged through the exhaust port. This process of charging and discharging gas was repeated 4 times to exhaust the oxygen in the reactor. The temperature of the reactor was programmed to rise to 180 °C, and then 1 MPa of oxygen was introduced for wet catalytic oxidation with a stirring speed of 800 r / min. After reacting for 3 h, the COD concentration of the treated solution was measured with a COD tester, and the COD removal efficiency of the catalyst was calculated. The results showed that the COD degradation efficiency of catalyst A-2 for high-concentration organic wastewater was 91.0%. After 20 cycles of reaction, the COD degradation efficiency remained above 90%.

[0061] The embodiments described above are only used to describe the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a catalyst for treating high-salt high-concentration organic wastewater, characterized in that, It includes the following steps: Perform surface functionalization on the TiO2 support material to obtain a siliconophilic TiO2 support material; Introduce a ruthenium complex into the S-1 zeolite precursor solution to obtain an S-1 zeolite precursor solution with in-situ confined ruthenium; Immerse the siliconophilic TiO2 support material into the S-1 zeolite precursor solution with in-situ confined ruthenium, perform hydrothermal crystallization, take out the siliconophilic TiO2 support material, dry it and then calcine it to prepare a catalyst for treating high-concentration organic wastewater containing salt; The temperature of the hydrothermal crystallization is 150-180 °C, and the time is 24-72 h; The temperature of the calcination is 400-600 °C; The surface functionalization treatment is to immerse the TiO2 support material into a silane coupling agent solution, stir it and then dry it to complete the surface functionalization treatment; The concentration of the silane coupling agent in the silane coupling agent solution is 1-3 wt.%, and the silane coupling agent is γ-aminopropyltriethoxysilane; The ruthenium complex is prepared by adding a complexing agent to an aqueous solution containing Ru 3+ ; The complexing agent is at least one of ethylenediamine and citric acid.

2. The preparation method of the catalyst for treating high-salt high-concentration organic wastewater according to claim 1, characterized in that, The TiO2 support material is strip-shaped.

3. The preparation method of the catalyst for treating high-salt high-concentration organic wastewater according to claim 1, characterized in that, The solid-liquid ratio of the functionalized TiO2 support material to the S-1 zeolite precursor solution with in-situ confined ruthenium is 1 g:10-30 mL.

4. A catalyst for treating high-concentration organic wastewater containing salt prepared by the preparation method of the catalyst for treating high-concentration organic wastewater containing salt according to any one of claims 1-3.

5. Use of the catalyst for treating high-salt high-concentration organic wastewater according to claim 4 in wet catalytic oxidation of high-salt high-concentration organic wastewater, characterized in that, In the high-concentration organic wastewater containing salt, the COD concentration is 20000-50000 mg / L, and the salt content is 5-10 wt.%.

6. The application according to claim 5, wherein The wet catalytic oxidation is carried out under the conditions of a temperature of 180-270 °C and an oxygen partial pressure of 1-3 MPa, and the concentration of the catalyst for treating high-concentration organic wastewater containing salt is 1-6 g / L.

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