Copper-loaded sba-15 catalysts, methods for their preparation and use

Abstract

The application discloses a preparation method and application of a copper-loaded SBA-15 catalyst. The catalyst is prepared by twice hydrothermal crystallization, in which Zr is doped onto SBA-15 in the first crystallization, then the pH value of the first crystallization product is adjusted to 5.5-6.0 by using alkali liquor to promote the hydrolysis of copper ions, and the hydrolysis product of Cu2+ is uniformly deposited onto SBA-15 by the second crystallization to obtain the copper-loaded SBA-15 catalyst. The copper component on the catalyst is uniformly dispersed, the catalyst has high activity, and the catalyst can better catalyze the oxidation of tetracycline in water at normal temperature and normal pressure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalytic materials and water treatment, and particularly relates to a preparation method of a copper-loaded SBA-15 catalyst and application of the catalyst in catalytic oxidation of tetracycline in water. BACKGROUND

[0002] SBA-15 is one of important members of mesoporous silica-based materials, has a two-dimensional hexagonal mesoporous structure, a regular pore size distribution, a large pore size (which can reach 30 nm), a relatively thick pore wall (3-9 nm) and a large specific surface area (generally 700-1100 m2 / g), and provides a basis for the catalyst carrier. Due to the strong acidic conditions for synthesizing SBA-15, metal ions (Mn+) mainly exist in the form of cations after being added into the synthesis system, and it is difficult to form M-O-Si bonds with Si. The ordinary impregnation method is easy to generate metal oxide particles, which are aggregated on the surface of the carrier (such as patent: application number 201410197447.2). As known in the catalytic field, once the active component generates larger particles, the contact between the active sites and the target reactants will be greatly reduced, thereby affecting the catalytic performance, and therefore, improving the dispersion of the active component is one of the key technologies for improving the catalytic performance. Copper (Cu) is one of the commonly used active components for catalytic oxidation of organic matters in water, and it is of great significance to study a preparation method of a suitable Cu-loaded SBA-15 catalyst.

[0003] Tetracycline is an important antibiotic, which is often used to control diseases of fish in water, promote the growth of fish, improve the feed utilization rate and the like. The residual tetracycline in aquatic products can produce toxicity to the entire ecological environment through the food chain, and harm the health of human beings. The tetracycline in wastewater has a strong inhibitory effect on microorganisms, and the molecular structure is complex, and the biodegradability is not ideal. In addition, some pharmaceutical enterprises are facing the problem of difficulty in meeting the standard discharge of wastewater. Catalytic oxidation is an important method for treating tetracycline wastewater, and due to the complex molecular structure and large size of tetracycline, the catalyst with mesoporous material as the carrier is a better choice. SUMMARY

[0004] The present application aims to provide a preparation method of a copper-loaded SBA-15 mesoporous catalyst with uniform dispersion of active components. The catalyst has a large specific surface area, good stability, and can effectively catalyze and oxidize to remove tetracycline in water.

[0005] Technical solution: Use triblock copolymer (EO20PO70EO20) as a template agent, tetraethyl orthosilicate (TEOS) as a silicon source, and hydrochloric acid as an acid source as the basic raw material for synthesizing SBA-15. In order to promote the dispersion of Cu components on SBA-15 and improve the performance of SBA-15, a zirconium source and an inorganic salt are added on the basis of adding a copper source, and a copper-loaded SBA-15 catalyst is prepared by a two-step pH adjustment method.

[0006] The specific steps of the preparation method are:

[0007] 1) Dissolve EO20PO70EO20 in an aqueous hydrochloric acid solution to form an EO20PO70EO20-containing mixed aqueous solution, stir at a constant temperature of 35-40 DEG C, and after complete dissolution, add a copper source, a zirconium source and an inorganic salt to form a mixed solution.

[0008] 2) Slowly drop TEOS into the above-mentioned mixed solution containing EO20PO70EO20, and stir at a constant temperature of 35-40 DEG C for 24.0 h to form a mixture.

[0009] 3) Put the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, put it into an oven at 100 DEG C for the first crystallization, take it out after 24.0 h, and cool it. Adjust the pH value of the first crystallization product to 5.5-6.0 with lye, and then put it into an oven at 100 DEG C for the second crystallization, take it out after 4.0-12.0 h. After filtration, washing and drying, the copper-loaded SBA-15 molecular sieve raw powder is obtained.

[0010] 4) The copper-loaded SBA-15 molecular sieve raw powder is calcined at a high temperature of 550 DEG C in air for 4.0-8.0 h to obtain a copper-loaded SBA-15 catalyst with uniform dispersion of active components.

[0011] The application promotes the hydrolysis of copper ions by the easy hydrolysis characteristics of zirconium ions (Zr4+) and the simultaneous addition of inorganic salt, and Zr4+ is doped into the pore wall of SBA-15 under strong acid conditions in the first crystallization. Then the pH value of the first crystallization product is adjusted to 5.5-6.0 with lye to promote the hydrolysis of copper ions, and the hydrolysis product of Cu2+ is uniformly deposited on SBA-15 through the second crystallization. Through high-temperature calcination, the hydrolysis product of Cu2+ reacts with H+ on the surface of Zr (after Zr is doped into SBA-15, the material has acidity and can provide H+, for example, literature [Journal of Molecular Catalysis A: Chemical 409 (2015) 69-78]), which promotes the uniform dispersion of Cu components on the carrier SBA-15, and a copper-loaded SBA-15 catalyst is prepared.

[0012] Further, the copper source in step 1) is copper nitrate or copper acetate.

[0013] Further, the zirconium source in step 1) is zirconium oxychloride or zirconium sulfate.

[0014] Further, the inorganic salt in step 1) is NaCl or KCl, which can improve the order of mesoporous SBA-15 material.

[0015] Further, the molar ratio of Si in tetraethyl orthosilicate to Cu2+ in solution in step 2) is 10-50:1. Too low Cu content affects its catalytic performance, and too high Cu content affects the order and specific surface area of the carrier SBA-15.

[0016] Further, the molar ratio of Si in tetraethyl orthosilicate to Zr in solution in step 2) is 10-50:1. Too low Zr content affects its dispersion of copper, and too high Zr content affects the order of the carrier SBA-15.

[0017] Further, the alkaline aqueous solution in step 3) is ammonia or sodium hydroxide aqueous solution. The pH value of the first crystallization product is adjusted to 5.5-6.0 with the lye, and too low pH value is not conducive to the hydrolysis of Cu2+, and too high pH value is easy to form aggregated Cu(OH)2 precipitate.

[0018] The catalyst prepared by the above method is used for catalyzing the oxidation of tetracycline in water. The catalyst is put into a tetracycline-containing aqueous solution, H2O2 is added as an oxidizing agent, and the reaction is carried out at normal temperature and pressure for 1.0-6.0 h. After filtering the catalyst, the residual tetracycline concentration in the water is determined.

[0019] Beneficial effects: The copper-loaded SBA-15 catalyst is prepared by the twice crystallization method. In the first crystallization process, Zr is doped into the SBA-15 framework, in the second crystallization process, pH adjustment is used to promote the hydrolysis of copper salt, and after calcination, the acidity of Zr is used to promote the uniform distribution of copper ions, solving the problem of easy formation of copper oxide particles of Cu component on SBA-15. The catalyst has high activity and can better catalyze the oxidation of tetracycline in water at normal temperature and pressure. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The XRD spectrum of the product prepared in Example 1. DETAILED DESCRIPTION

[0021] The following examples will further illustrate the present application, but the scope of the present application is not limited thereto at all.

[0022] Example 1:

[0023] 1. Weigh 2.0g of EO20PO70EO20 template agent and place it in 70mL of 0.25mol / L hydrochloric acid aqueous solution.

[0024] The solution was dissolved by stirring at a constant temperature of 40℃. Then, 0.26 g Cu(NO3)·3H2O, 0.34 g ZrOCl2·8H2O, and 1.0 g NaCl were added. After complete dissolution, 4.4 g TEOS was weighed and slowly added dropwise to the solution. The mixture was stirred at a constant temperature of 40℃ for 24.0 h. The mixture was then placed in a stainless steel reactor lined with polytetrafluoroethylene and crystallized at 100℃ for 24.0 h. After cooling, the pH of the mixture was adjusted to 6.0 with a 30% NaOH aqueous solution, and then crystallized again for 8.0 h. After washing, filtration, and calcination at 550℃ for 6.0 h, copper-loaded SBA-15 catalyst was obtained, labeled Cu / Zr / SBA-15(20,20), where the first 20 represents the Si / Cu molar ratio and the second 20 represents the Si / Zr molar ratio.

[0025] To test the dispersing effect of Zr on copper, Cu / SBA-15(20) was prepared. Except for the absence of a Zr source, the other steps were the same as those for Cu / Zr / SBA-15(20,20), where 20 represents the Si / Cu molar ratio.

[0026] To examine whether copper, zirconium, and inorganic salts affect the SBA-15 support, SBA-15 was prepared, which was identical to the preparation method of Cu / Zr / SBA-15(20,20) except that copper, zirconium, and inorganic salts were not added.

[0027] Application: 100 mL of a 50 mg / L tetracycline aqueous solution was placed in a 250 mL glass container, along with 0.01 g of catalyst Cu / Zr / SBA-15(20,20) and 0.27 mL of 30% H2O2. After stirring at 30 °C for 4.0 h, the concentration of residual tetracycline in the aqueous solution was determined using a UV spectrophotometer. The removal rate of tetracycline was 93.2%, and the total organic carbon removal rate (TOC) was 66.7%.

[0028] 2. Weigh 2.0 g of EO20PO70EO20 template agent and place it in 70 mL of 0.25 mol / L hydrochloric acid aqueous solution.

[0029] 40°C under constant temperature stirring to dissolve. Then 0.26g Cu(NO3)3H2O, 0.17g ZrOCl2*8H2O and 1.0g NaCl were added, after complete dissolution, 4.4g TEOS was slowly added into the above solution, under constant temperature stirring at 40°C for 24.0h. The mixture was loaded into a stainless steel autoclave with a polytetrafluoroethylene liner, crystallization was carried out at 100°C for 24.0h, after cooling, the pH was adjusted to 6.0 with ammonia water, and then the mixture was loaded into the autoclave for crystallization for 8.0h. After washing, filtering and calcination at 550°C for 6.0h, Cu loaded SBA-15 catalyst was obtained, which was marked as Cu / Zr / SBA-15(20,40), wherein 20 represents the Si / Cu molar ratio and 40 represents the Si / Zr molar ratio.

[0030] Application: 100mL tetracycline aqueous solution with a concentration of 50mg / L was taken into a 250mL glass container, 0.01g Cu / Zr / SBA-15(20,40) and 0.18mL 30% H2O2 were added, after stirring at 30°C for 2.0h, the residual tetracycline concentration in water was determined by liquid chromatography, the removal rate of tetracycline was 83.5% and the total organic carbon removal rate (TOC) was 47.6%.

[0031] 3. 2.0g EO20PO70EO20 template was weighed and placed in 70mL 0.25mol / L hydrochloric acid aqueous solution, under constant temperature stirring at 40°C for 24.0h to dissolve.

[0032] 40°C under constant temperature stirring to dissolve. Then 0.26g Cu(NO3)3H2O, 0.17g ZrOCl2*8H2O and 1.0g NaCl were added, after complete dissolution, 4.4g TEOS was slowly added into the above solution, under constant temperature stirring at 40°C for 24.0h. The mixture was loaded into a stainless steel autoclave with a polytetrafluoroethylene liner, crystallization was carried out at 100°C for 24.0h, after cooling, the pH was adjusted to 6.0 with ammonia water, and then the mixture was loaded into the autoclave for crystallization for 8.0h. After washing, filtering and calcination at 550°C for 6.0h, Cu loaded SBA-15 catalyst was obtained, which was marked as Cu / Zr / SBA-15(20,40), wherein 20 represents the Si / Cu molar ratio and 40 represents the Si / Zr molar ratio.

[0033] Cu / Zr / SBA-15(20,13), wherein 20 represents the Si / Cu molar ratio and 13 represents the Si / Zr molar ratio.

[0034] Application: 100mL tetracycline aqueous solution with a concentration of 50mg / L was taken into a 250mL glass container, 0.01g Cu / Zr / SBA-15(20,40) and 0.18mL 30% H2O2 were added, after stirring at 30°C for 2.0h, the residual tetracycline concentration in water was determined by liquid chromatography, the removal rate of tetracycline was 83.5% and the total organic carbon removal rate (TOC) was 47.6%.

[0035] 4. Weigh 2.0 g of EO20PO70EO20 template agent into 70 mL of 0.25 mol / L aqueous hydrochloric acid solution, and stir at a constant temperature of 40 °C to dissolve it. Then add 0.13 g of Cu(NO3)3H2O, 0.34 g of ZrOCl2*8H2O and 1.0 g of NaCl, and after they are completely dissolved, weigh 4.4 g of TEOS and slowly add it to the above solution, and stir at a constant temperature of 40 °C for 24 h. Put the mixed solution into a polytetrafluoroethylene-lined stainless steel autoclave, and crystallize at 100 °C for 24 h. After taking it out and cooling, adjust the pH to 6.0 with aqueous ammonia, and then put it into the autoclave to crystallize for 8 h. After washing, filtering, and calcining at 550 °C for 6 h, a Cu-loaded SBA-15 catalyst is obtained, which is marked as Cu / Zr / SBA-15(40,20), wherein 40 represents the Si / Cu molar ratio and 20 represents the Si / Zr molar ratio.

[0036] 40 °C to dissolve it. Then add 0.13 g of Cu(NO3)3H2O, 0.34 g of ZrOCl2*8H2O and 1.0 g of NaCl, and after they are completely dissolved, weigh 4.4 g of TEOS and slowly add it to the above solution, and stir at a constant temperature of 40 °C for 24 h. Put the mixed solution into a polytetrafluoroethylene-lined stainless steel autoclave, and crystallize at 100 °C for 24 h. After taking it out and cooling, adjust the pH to 6.0 with aqueous ammonia, and then put it into the autoclave to crystallize for 8 h. After washing, filtering, and calcining at 550 °C for 6 h, a Cu-loaded SBA-15 catalyst is obtained, which is marked as Cu / Zr / SBA-15(40,20), wherein 40 represents the Si / Cu molar ratio and 20 represents the Si / Zr molar ratio.

[0037] Application: Take 100 mL of a tetracycline aqueous solution with a concentration of 50 mg / L into a 250 mL glass container, add 0.01 g of the catalyst, 0.18 mL of 30% H2O2, and stir at 30 °C for 2.0 h. After that, determine the residual tetracycline concentration by liquid chromatography, and the removal rate of tetracycline is 70.5%, and the total organic carbon removal rate (TOC) is 41.0%.

[0038] 5. Weigh 2.0 g of EO20PO70EO20 template agent into 70 mL of 0.25 mol / L aqueous hydrochloric acid solution, and stir at a constant temperature of 40 °C to dissolve it. Then add 0.13 g of Cu(NO3)3H2O, 0.34 g of ZrOCl2*8H2O and 1.0 g of NaCl, and after they are completely dissolved, weigh 4.4 g of TEOS and slowly add it to the above solution, and stir at a constant temperature of 40 °C for 24 h. Put the mixed solution into a polytetrafluoroethylene-lined stainless steel autoclave, and crystallize at 100 °C for 24 h. After taking it out and cooling, adjust the pH to 6.0 with aqueous ammonia, and then put it into the autoclave to crystallize for 8 h. After washing, filtering, and calcining at 550 °C for 6 h, a Cu-loaded SBA-15 catalyst is obtained, which is marked as Cu / Zr / SBA-15(40,20), wherein 40 represents the Si / Cu molar ratio and 20 represents the Si / Zr molar ratio.

[0039] 40 °C to dissolve it. Then add 0.13 g of Cu(NO3)3H2O, 0.34 g of ZrOCl2*8H2O and 1.0 g of NaCl, and after they are completely dissolved, weigh 4.4 g of TEOS and slowly add it to the above solution, and stir at a constant temperature of 40 °C for 24 h. Put the mixed solution into a polytetrafluoroethylene-lined stainless steel autoclave, and crystallize at 100 °C for 24 h. After taking it out and cooling, adjust the pH to 6.0 with aqueous ammonia, and then put it into the autoclave to crystallize for 8 h. After washing, filtering, and calcining at 550 °C for 6 h, a Cu-loaded SBA-15 catalyst is obtained, which is marked as Cu / Zr / SBA-15(40,20), wherein 40 represents the Si / Cu molar ratio and 20 represents the Si / Zr molar ratio.

[0040] Application: 100 mL of tetracycline aqueous solution with concentration of 50 mg / L was put into 250 mL glass container, 0.01 g of catalyst Cu / Zr / SBA-15 (20, 20), 0.27 mL of 30% H2O2 was added, after stirring at 30 ℃ for 2.0 h, the residual tetracycline concentration was determined by UV spectrophotometer, the removal rate of tetracycline was 89.2%, and the total organic carbon removal rate (TOC) was 60.5%.

[0041] Figure 1 For the XRD patterns of Cu / Zr / SBA-15 (20, 20), Cu / SBA-15 (20) and SBA-15 in Example 1, the characteristic diffraction peaks of CuO at 2θ angles of 35.54°, 38.70° and 48.72° appeared on the Cu / SBA-15 (20) spectrum line, and the characteristic diffraction peaks of CuO did not appear on the Cu / Zr / SBA-15 (20, 20) spectrum line, indicating that the copper component was highly uniformly dispersed.

[0042] Although the present application is illustrated and described with reference to the preferred embodiments, it is understood that various changes and modifications can be made to the present application without departing from the scope of the claims of the present application.

Claims

1. The use of a copper-loaded SBA-15 catalyst for catalyzing the oxidation of tetracycline in water at normal temperature and pressure, characterized in that The catalyst is prepared by the following steps: tri-block copolymer, copper source, zirconium source and inorganic salt are added into hydrochloric acid aqueous solution with pH<2.0 respectively, and then tetraethyl orthosilicate is added dropwise after constant temperature dissolution; after constant temperature stirring for 24.0 h, first hydrothermal crystallization is carried out; then the pH value of the first crystallization product is adjusted to 5.5-6.0 by alkali solution, second crystallization is carried out, and after washing, drying and calcination, the copper component dispersed uniformly, the copper-loaded SBA-15 catalyst is obtained; The preparation method of the copper-loaded SBA-15 catalyst comprises the following steps: 1) At 35.0-40.0 ℃, the triblock copolymer EO 20 PO 70 EO 20 Dissolve the copper source, the zirconium source and the inorganic salt in the hydrochloric acid aqueous solution with pH < 2.0 to form a mixed solution; 2) tetraethyl orthosilicate TEOS is added dropwise into the above mixture, and after stirring at 35.0-40.0 ℃ for 24.0 h, the mixture is put into a stainless steel reaction kettle with a polytetrafluoroethylene lining, first crystallization is carried out, and crystallization is carried out at 100 ℃ for 24.0 h to obtain the crystallization product; 3) the pH value of the crystallization product is adjusted to 5.5-6.0 by alkali solution under stirring, second crystallization is carried out, and crystallization is carried out at 100 ℃ for 4.0-12.0 h; 4) the second crystallization product is washed with water and dried to obtain the copper-loaded SBA-15 molecular sieve raw powder; 5) the copper-loaded SBA-15 molecular sieve raw powder is heated to 550 ℃ at a rate of 2 ℃ / min in an air atmosphere, and then calcined at 550 ℃ for 4.0-8.0 h to obtain the copper-loaded SBA-15 catalyst.

2. Use of a copper-containing SBA-15 catalyst according to claim 1, characterized in that, The copper source is copper nitrate or copper acetate.

3. Use of a copper-containing SBA-15 catalyst according to claim 1, characterized in that, The zirconium source is zirconium oxychloride or zirconium sulfate.

4. Use of a copper-containing SBA-15 catalyst according to claim 1, characterized in that, The molar ratio of tetraethyl orthosilicate to copper in the copper source was 10-50:1, and the molar ratio of tetraethyl orthosilicate to zirconium in the zirconium source was 10-50:1, TEOS:EO 20 PO 70 EO 20 : HCl : H2O molar ratio = 1.0 : 0.016 : 3.0 : 186.

0.

5. Use of a copper-containing SBA-15 catalyst according to claim 1, characterized in that, The inorganic salt is NaCl or KCl, and the mass ratio of tetraethyl orthosilicate to inorganic salt added is 9-3:

1.

6. Use of a copper-containing SBA-15 catalyst according to claim 1, characterized in that, The alkali solution is sodium hydroxide aqueous solution or ammonia solution.

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