Catalyst for treating salt-containing high-concentration organic wastewater and preparation method thereof

Abstract

The invention discloses a catalyst for treating salt-containing high-concentration organic wastewater and a preparation method of the catalyst, and belongs to the technical field of noble metal catalysts and sewage treatment. The preparation method comprises the following steps: carrying out surface functionalization treatment on a TiO2 carrier material to obtain a silicon-philic TiO2 carrier material; introducing a ruthenium complex into the S-1 molecular sieve precursor solution to obtain an S-1 molecular sieve precursor solution of in-situ confined ruthenium; and immersing the silicon-philic TiO2 carrier material into the S-1 molecular sieve precursor solution of the in-situ confinement ruthenium, carrying out hydrothermal crystallization, taking out the TiO2 carrier material, drying, and roasting to prepare the catalyst for treating salt-containing high-concentration organic wastewater. Through the confinement design of ruthenium, the use amount of precious metal is greatly reduced, and the economical efficiency of the catalyst is improved. The hydrophobic structure of the S-1 molecular sieve is combined with the high mechanical strength of TiO2, so that the catalyst can stably operate for a long time in a salt-containing high-concentration organic wastewater environment.

Description

Technical Field

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

[0002] Catalytic wet oxidation (CWAO) technology is an important method for treating high-concentration organic wastewater. It converts refractory organic matter into non-toxic small molecules through oxidation under high temperature and high pressure conditions. However, existing catalysts still have significant problems in practical applications. The current mainstream carrier is titanium oxide (TiO2), which is often loaded with precious metals (such as Ru, Pt, Pd) to enhance catalytic activity. However, such catalysts generally face the following challenges: (1) The reaction is usually carried out under high temperature and high pressure conditions, and precious metal particles are easily lost due to migration, agglomeration or dissolution, resulting in reduced activity and insufficient stability; (2) The traditional loading method of precious metals is difficult to effectively reduce the metal dosage; (3) In saline wastewater, Cl - The plasma has a serious poisoning effect on the precious metal center, significantly weakening the salt resistance of the catalyst; (4) The carbon deposition problem is widespread, and some reaction intermediates (such as phenol and quinones) easily form a carbon deposition layer on the catalyst surface, covering the active sites and further accelerating the catalyst deactivation. Summary of the invention

[0003] In response to the above problems, the present invention provides a catalyst for treating high-concentration organic wastewater containing salt and a method for preparing the same. With the S-1 molecular sieve of confined precious metal ruthenium as the core, combined with a strip-shaped titanium oxide carrier, the uniform combination of the molecular sieve and the carrier is achieved through hydrothermal in-situ growth technology. Different from the traditional ruthenium loading method, the present invention directly introduces a ruthenium source during the synthesis of the S-1 molecular sieve, so that ruthenium is embedded in the microporous structure of the molecular sieve in a confined manner, significantly improving the dispersion of precious metals and reducing the amount of active metals. At the same time, the S-1 molecular sieve can selectively adsorb non-polar organic pollutants and effectively alleviate the problem of carbon deposition; its skeleton structure provides protection for ruthenium particles, greatly reducing the risk of metal loss in a salty environment. In addition, the S-1 molecular sieve of confined ruthenium is uniformly grown on the surface of the titanium oxide carrier through a hydrothermal crystallization process, avoiding the problem of uneven coverage of the molecular sieve that may exist in the traditional coating process, and further improving the mechanical stability and thermal stability of the catalyst. The present invention provides a catalyst solution with high efficiency, low cost, strong salt resistance and excellent anti-carbon deposition performance for wet catalytic oxidation treatment of high-concentration organic wastewater through technical innovation in confining precious metals in molecular sieves and optimizing the carrier combination method.

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

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

[0006] Performing surface functionalization treatment on TiO2 carrier material to obtain silicon-philic TiO2 carrier material;

[0007] Introducing a ruthenium complex into an S-1 molecular sieve precursor solution to obtain an S-1 molecular sieve precursor solution with in-situ confined ruthenium;

[0008] The siliciphilic TiO2 carrier material is immersed in the S-1 molecular sieve precursor solution of the in-situ confined ruthenium, hydrothermally crystallized, and the siliciphilic TiO2 carrier material is taken out, dried and then calcined to obtain a catalyst for treating high-concentration salt-containing organic wastewater.

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

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

[0011] Strip-shaped TiO2 carrier materials can make the prepared catalyst have a larger specific surface area.

[0012] Preferably, the TiO2 carrier material is subjected to surface pretreatment before the functionalization treatment to remove water and organic matter on the surface of the TiO2 carrier material.

[0013] Preferably, the surface functionalization treatment is performed by immersing the TiO2 carrier material in a silane coupling agent solution, stirring and then drying to complete the surface functionalization treatment.

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

[0015] Preferably, the ruthenium complex is composed of 3+ It is prepared by adding a complexing agent to an aqueous solution.

[0016] Optionally, the Ru 3+ It is provided by a soluble ruthenium salt, which 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 ethyl orthosilicate, and the template agent is tetrapropylammonium hydroxide.

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

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

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

[0021] The second technical solution of the present invention is to provide a catalyst for treating high-concentration salt-containing organic wastewater, which is prepared according to the above-mentioned method for preparing the catalyst for treating high-concentration salt-containing organic wastewater.

[0022] The third technical solution of the present invention is to provide an application of the above-mentioned catalyst for treating saline and high-concentration organic wastewater in wet catalytic oxidation of saline and high-concentration organic wastewater, wherein the COD concentration of the saline and high-concentration organic wastewater is 20,000 to 50,000 mg / L, and the salt content is 5 to 10 wt.%.

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

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

[0025] The present invention innovatively combines the S-1 molecular sieve with in-situ confined ruthenium with a TiO2 carrier to prepare a precious 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 treatment of saline and high-concentration organic wastewater by wet catalytic oxidation (CWAO). Through the confinement design of ruthenium, the amount of precious metal is greatly reduced, and the economy of the catalyst is improved. The hydrophobic structure of the S-1 molecular sieve combined with the high mechanical strength of TiO2 enables the catalyst to operate stably for a long time in a saline and high-concentration organic wastewater environment. It solves the problem of performance degradation of traditional catalysts in saline environments due to agglomeration, loss of active sites and carbon deposition, and provides an efficient and sustainable solution for complex industrial wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the XRD pattern of the A-1 catalyst prepared in Example 1. DETAILED DESCRIPTION

[0027] Now, various exemplary embodiments of the present invention are described in detail, which should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described 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 range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

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

[0030] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0031] Example 1

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

[0033] TiO2 surface cleaning and functionalization: The strip TiO2 was cleaned with 0.1M nitric acid solution and stirred at room temperature for 2 hours. After washing, it was calcined at 350℃ for 2 hours to remove impurities. It was immersed in 1wt.% APTES solution and stirred for 6 hours, then washed with deionized water and dried at 100℃.

[0034] Preparation of S-1 molecular sieve precursor solution: 0.02g of ruthenium chloride was dissolved in 20mL of deionized water, 0.4g of ethylenediamine was added as a complexing agent, and stirred for 1h to form solution A. 8mL of tetraethyl orthosilicate (TEOS) was added to 10mL of deionized water, and stirred until it was completely hydrolyzed to form a uniform silicon source solution, and then 13g of tetrapropylammonium hydroxide (TPAOH) was added and stirred for 2h to form solution B. Finally, solution A was added dropwise to solution B and stirred for 5h.

[0035] Catalyst preparation: Functionalized TiO2 (1 g) was immersed in the prepared S-1 molecular sieve precursor solution (liquid-solid ratio 20 mL: 1 g) and hydrothermally crystallized at 170 ° C for 72 h. After washing and drying, it was calcined at 550 ° C for 6 h 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 ,from Figure 1 It can be seen that the substance on the surface of the molded catalyst is mainly S-1 molecular sieve, indicating that the molecular sieve is successfully attached to the surface of the strip TiO2. The reason why the characteristic peak of Ru is not detected is mainly because its content is low and highly dispersed.

[0037] High concentration organic wastewater treatment:

[0038] The performance of the catalyst was evaluated by intermittent reaction in an autoclave. 0.15g of the catalyst was mixed with 50mL of phenol solution and placed in an autoclave. The COD concentration of the phenol solution was 20000mg / L and the salt content was 5wt.%. After the reactor was sealed, 0.5MPa of nitrogen was flushed into it, and then the exhaust port was opened to discharge the gas. The filling and discharging of the gas was repeated 4 times to exhaust the oxygen in the reactor. The reactor was heated to 250°C, and then 2MPa of oxygen was introduced into it to start wet catalytic oxidation, with a stirring speed of 500r / min. After 3h of reaction, 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-1 for high-concentration organic wastewater was 95%.

[0039] Example 2

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

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

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

[0043] Catalyst preparation: Functionalized TiO2 (1 g) was immersed in the prepared S-1 molecular sieve 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] High concentration organic wastewater treatment:

[0045] The performance of the catalyst was evaluated by intermittent reaction in an autoclave. 0.4 g of the catalyst was mixed with 100 mL of phenol solution and placed in an autoclave. The COD concentration of the phenol solution was 30,000 mg / L and the salt content was 6 wt.%. After the autoclave was sealed, 0.5 MPa of nitrogen was flushed into it, and then the exhaust port was opened to discharge the gas. The oxygen in the autoclave was discharged four times. The autoclave was heated to 250 ° C, and then 2.5 MPa of oxygen was introduced into it to start wet catalytic oxidation, with a stirring speed of 600 r / min. After 2 hours of reaction, 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 90.5%.

[0046] Example 3

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

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

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

[0050] Catalyst preparation: 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] High concentration organic wastewater treatment

[0052] The performance of the catalyst was evaluated by intermittent reaction in an autoclave. 0.25 g of the catalyst was mixed with 50 ml of phenol solution and placed in an autoclave. The COD concentration of the phenol solution was 40,000 mg / L and the salt content was 7 wt.%. After the autoclave was sealed, 0.5 MPa of nitrogen was flushed into it, and then the exhaust port was opened to discharge the gas. The filling and discharging of the gas was repeated 4 times to exhaust the oxygen in the autoclave. The autoclave was heated to 250 ° C, and then 3 MPa of oxygen was introduced into it to start wet catalytic oxidation, with a stirring speed of 500 r / min. After 2 hours of reaction, 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-3 for high-concentration organic wastewater was 92.4%.

[0053] Example 4

[0054] Preparation of precious metal catalyst A-1: ​​same as in Example 1.

[0055] High concentration organic wastewater treatment:

[0056] The performance of the catalyst was evaluated by intermittent reaction in an autoclave. 0.6 g of the catalyst was mixed with 100 mL of phenol solution and placed in an autoclave. The COD concentration of the phenol solution was 50,000 mg / L and the salt content was 8 wt.%. After the autoclave was sealed, 0.5 MPa of nitrogen was flushed into it, and then the exhaust port was opened to discharge the gas. The oxygen in the autoclave was discharged four times. The autoclave was heated to 270 ° C, and then 3 MPa of oxygen was introduced into it to start wet catalytic oxidation, with a stirring speed of 800 r / min. After 4 hours of reaction, 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-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 precious metal catalyst A-2: Same as Example 2.

[0059] High concentration organic wastewater treatment:

[0060] The performance of the catalyst was evaluated by intermittent reaction in an autoclave. 0.2 g of the catalyst was mixed with 100 mL of phenol solution and placed in an autoclave. The COD concentration of the phenol solution was 25000 mg / L and the salt content was 5 wt.%. After the autoclave was sealed, 0.5 MPa of nitrogen was flushed into it, and then the exhaust port was opened to discharge the gas. The oxygen in the autoclave was discharged four times. The autoclave was heated to 180 ° C, and then 1 MPa of oxygen was introduced into it to start wet catalytic oxidation, with a stirring speed of 800 r / min. After 3 hours of reaction, 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%, and after 20 cycles of reaction, the COD degradation efficiency remained above 90%.

[0061] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A catalyst for treating high-concentration organic wastewater containing salt and a preparation method thereof, characterized in that: The following steps are involved: Performing surface functionalization treatment on TiO2 carrier material to obtain silicon-philic TiO2 carrier material; Introducing a ruthenium complex into an S-1 molecular sieve precursor solution to obtain an S-1 molecular sieve precursor solution with in-situ confined ruthenium; The siliciphilic TiO2 carrier material is immersed in the S-1 molecular sieve precursor solution of the in-situ confined ruthenium, hydrothermally crystallized, and the siliciphilic TiO2 carrier material is taken out, dried and then calcined to obtain a catalyst for treating high-concentration salt-containing organic wastewater.

2. The method for preparing a catalyst for treating high-concentration salt-containing organic wastewater according to claim 1, characterized in that: The TiO2 carrier material is in strip shape.

3. The method for preparing a catalyst for treating high-concentration salt-containing organic wastewater according to claim 1, characterized in that: The surface functionalization treatment is to immerse the TiO2 carrier material in a silane coupling agent solution, stir and then dry to complete the surface functionalization treatment.

4. The method for preparing a catalyst for treating high-concentration salt-containing organic wastewater according to claim 1, characterized in that: The ruthenium complex is composed of 3+ It is prepared by adding a complexing agent to an aqueous solution.

5. The method for preparing a catalyst for treating high-concentration salt-containing organic wastewater according to claim 1, characterized in that: The solid-to-liquid ratio of the functionalized TiO2 carrier material to the S-1 molecular sieve precursor solution of in-situ confined ruthenium is 1g:10-30mL.

6. The method for preparing a catalyst for treating high-concentration salt-containing organic wastewater according to claim 1, characterized in that: The temperature of the hydrothermal crystallization is 150-180° C., and the time is 24-72 hours.

7. The method for preparing a catalyst for treating high-concentration salt-containing organic wastewater according to claim 1, characterized in that: The calcination temperature is 400-600°C.

8. A catalyst for treating saline high-concentration organic wastewater prepared according to the method for preparing a catalyst for treating saline high-concentration organic wastewater according to any one of claims 1 to 7.

9. Use of the catalyst for treating saline high-concentration organic wastewater according to claim 8 in wet catalytic oxidation of saline high-concentration organic wastewater, characterized in that: The COD concentration of the saline and high-concentration organic wastewater is 20,000 to 50,000 mg / L, and the salt content is 5 to 10 wt.%.

10. The use according to claim 9, characterized in that: The wet catalytic oxidation is carried out at a temperature of 180-270° C. and an oxygen partial pressure of 1-3 MPa. The concentration of the catalyst for treating the salt-containing high-concentration organic wastewater is 1-6 g / L.

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