Alumina carrier catalyst for ozone advanced oxidation treatment of organic sewage as well as preparation method and application of alumina carrier catalyst

Abstract

The invention provides an alumina carrier catalyst for ozone advanced oxidation treatment of organic sewage and a preparation method and application thereof, and relates to the field of organic sewage treatment, the alumina carrier catalyst comprises the following basic components by mass: 4-12% of NiO, 3-5% of Mn, 3-6% of Si, and 37-90% of Al2O3; the alumina carrier is modified by a modifier nickel oxide or manganese-containing heteropoly acid, and the modification treatment adopts nickel nitrate with the concentration of 0.1-1.5 mol / l and a mixed suspension impregnation liquid of the nickel nitrate and the manganese-containing heteropoly acid. The catalyst is high in stability and high in catalytic activity, has an excellent catalytic oxidation effect on nonbiodegradable organic sewage, and can improve the ozone utilization rate, realize higher COD removal efficiency and reduce the operation cost.

Description

Technical Field

[0001] The invention relates to the field of organic sewage treatment, and in particular to an alumina-supported catalyst for advanced ozone oxidation treatment of organic sewage, and a preparation method and application thereof. Background Art

[0002] As a new and efficient method for treating organic pollutants, the advanced oxidation process mainly uses chemical means to produce strongly oxidizing free radicals and other active oxygen species in the system to degrade organic matter, ultimately achieving the purpose of removing pollutants, and has been widely used. The traditional Fenton method and sodium persulfate method are greatly restricted in actual use due to the large amount of sludge produced and the high cost of reagents. The ozone heterogeneous catalytic method has been widely used due to its high catalytic activity, long life and no sludge production. There are two main mechanisms for ozone to attack organic matter: one is direct oxidation of ozone molecules; the other is indirect oxidation by the decomposition of ozone to produce hydroxyl radicals. Among them, hydroxyl radicals have stronger oxidizing properties. How to selectively improve the efficiency of ozone catalytic decomposition to produce hydroxyl radicals, improve selectivity, and shorten the decomposition time is of great significance, among which high-efficiency catalysts are the core technology. At present, new heterogeneous catalysts have been developed a lot, including precious metal systems, metal acid systems, molecular sieve systems, etc.

[0003] Patent document No. 201710668026.7 discloses an ozone oxidation catalyst based on a γ-alumina ball carrier and its preparation method. The advantage is that the preparation steps are simple using the impregnation method, and the price is more than 50% lower than the average price of catalysts from mainstream manufacturers on the market, saving costs. However, the disadvantage is that there is only one type of loaded metal, the catalytic effect of the single-component catalyst is poor, and the removal rate of COD is low; and the loading method used is equal volume impregnation, which cannot guarantee sufficient catalyst loading.

[0004] Patent document No. 201210475655.5 discloses a method for preparing a supported two-component metal oxide ozone catalytic oxidation catalyst, which has the advantages of immersing γ-Al2O3 microspheres in hydrochloric acid for activation treatment, changing the pore structure of the carrier to increase the loading amount; the loading material is two metals, and the two-component catalyst improves the removal rate of COD and has a better catalytic effect. However, the disadvantage is that the metal oxide precursor solution is a mixture of two metals, and the loading amount and molar ratio of the two metals cannot be strictly controlled, which affects the catalytic effect of the catalyst.

[0005] Patent document No. 201510639519.9 discloses an ozone catalyst for difficult-to-biodegrade wastewater and its preparation method. The advantage is that in the preparation method of the ozone catalyst, the catalyst carrier and the catalyst precursor are modified respectively, so that the active components can be evenly dispersed and loaded, thereby having a higher removal rate for low-concentration difficult-to-biodegrade wastewater. However, the disadvantage is that the preparation process is complicated, the steps are cumbersome, and Au is used as an auxiliary agent, which greatly increases the preparation cost and is not suitable for widespread promotion and use.

[0006] Patent document No. 201510107275.X discloses a method for preparing an ozone catalyst by bonding an alumina mother ball and a catalytic mixture, which has the advantages of high adhesion strength of the catalytic mixture, preventing the loss of active components, ensuring the effective utilization of active components when the formed ozone catalyst is used, and reducing the production cost of the catalyst. However, the disadvantage is that the catalytic mixture is only sintered on the outer layer of the alumina mother ball, the content of effective components is low, the metal catalyst loading is insufficient, and the specific surface area of ​​the finished product is small, and the ball-forming process cannot accurately guarantee the strength of the catalyst particles.

[0007] According to the above analysis, it is necessary to develop high-performance catalysts that can improve ozone utilization, achieve higher COD removal rates, and reduce operating costs. Therefore, the development of a new catalyst system that tends to produce hydroxyl radicals, efficiently completes the mass transfer and separation process of organic matter, has a large specific surface area, and improves the utilization of metal active sites is of great significance for the development of new sewage treatment processes. Summary of the invention

[0008] The purpose of the present invention is to provide an alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone, and a preparation method and application thereof. The alumina catalyst for advanced oxidation treatment of ozone has high stability and high catalytic activity, has excellent catalytic oxidation effect on bio-refractory organic wastewater, can improve ozone utilization rate and reduce operating costs.

[0009] In order to achieve the above-mentioned purpose, the present invention provides an alumina supported catalyst for advanced oxidation treatment of organic wastewater with ozone, wherein the alumina supported catalyst is basically composed of: NiO4-12%, Mn 3-5%, Si 3-6%, Al2O377-90% in terms of mass ratio; the alumina support is modified with a modifier of nickel oxide or a manganese-containing heteropoly acid, wherein the modification treatment is carried out with a mixed suspension impregnation solution of nickel nitrate having a concentration of 0.1-1.5 mol / l and a manganese-containing heteropoly acid.

[0010] Preferably, the alumina carrier modification treatment adopts a combined impregnation and adsorption method, urea and ammonia water are used as precipitants, and the pH is adjusted to 10-12, and pure water is used for washing after precipitation.

[0011] Preferably, the modifier is a mixed oxide of manganese, nickel, silicon and aluminum.

[0012] Preferably, the alumina carrier has a specific surface area of ​​>25 m2 / g and a crystalline phase of α-A12O3.

[0013] Preferably, the lateral compression strength of the alumina carrier is greater than 35 kg / cm.

[0014] Through projection electron microscope image observation, the alumina supported catalyst for advanced oxidation treatment of organic wastewater with ozone provided by the present invention is of nanorod type, and the supported heteropolyacid particles are evenly distributed and embedded with the carrier, which can improve the catalyst stability.

[0015] The second aspect of the present invention provides a method for preparing an alumina-supported catalyst for advanced oxidation treatment of organic wastewater with ozone, comprising the following steps:

[0016] 1) High-temperature inorganic method to prepare alumina carrier with high strength, large specific surface area and suitable pore structure;

[0017] 2) Synthesize heteropolyacid system by template method;

[0018] 3) The alumina carrier obtained in step 1) is subjected to precipitation, impregnation and surface modification with a heteropolyacid system to prepare a catalyst.

[0019] Preferably, silicic acid is added during the synthesis of the alumina carrier in step 1) to prepare carriers with different requirements.

[0020] The third aspect of the present invention provides the use of the alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone of the present invention or the alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone prepared by the preparation method of the alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone of the present invention in wastewater treatment.

[0021] The beneficial effects of the present invention are:

[0022] Compared with the prior art, the alumina-supported catalyst for advanced oxidation treatment of organic wastewater with ozone obtained by the present invention further improves the performance of catalytic generation of hydroxyl radicals mainly through a novel heteropolyacid active system and a high specific surface area alumina support, wherein the developed highly active, stable and weather-resistant heteropolyacid system is combined with a high specific surface area support synthesis technology and a loading technology, and the obtained catalyst has high stability and high catalytic activity, has excellent catalytic oxidation effect on biodegradable organic wastewater, can improve ozone utilization, achieve higher COD removal efficiency, the COD removal efficiency can reach 70.6%, and reduce operating costs. DETAILED DESCRIPTION

[0023] The present invention is described below by specific examples to make the technical solution of the present invention easier to understand and grasp, but the present invention is not limited thereto. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0024] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope 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 described 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.

[0025] The present invention provides an alumina carrier catalyst for advanced oxidation treatment of organic wastewater with ozone, wherein the alumina carrier catalyst is basically composed of: NiO 4-12%, Mn 3-5%, Si 3-6%, Al2O3 77-90% in terms of mass ratio; the alumina carrier is modified by a modifier of nickel oxide or a manganese-containing heteropoly acid, wherein the modification treatment is carried out by using a mixed suspension impregnation solution of nickel nitrate with a concentration of 0.1-1.5 mol / l and a manganese-containing heteropoly acid.

[0026] The alumina carrier is modified by a modifier of nickel oxide or a manganese-containing heteropoly acid. The modified carrier changes the distribution of hydroxyl groups on the carrier surface, which is beneficial to increasing the loading intensity of the active components. In the early stage of preparing the catalyst, a carrier with high mechanical strength is selected to enhance the wear resistance of the catalyst.

[0027] Preferably, in order to ensure the modification effect on the Al2O3 carrier, the alumina carrier modification treatment adopts a combined impregnation and adsorption method, urea and ammonia water are used as precipitants, and the pH is adjusted to 10-12, and pure water is used for washing after precipitation.

[0028] Preferably, the modifier is a mixed oxide of manganese, nickel, silicon and aluminum.

[0029] When the ozone catalytic oxidation catalyst carrier is modified by an active metal oxide, the active component is not easily lost during a long-term multi-phase ozone catalytic oxidation reaction, thereby ensuring the life of the catalyst.

[0030] Preferably, the alumina carrier has a specific surface area of ​​>25 m2 / g and a crystalline phase of α-A12O3.

[0031] Preferably, the lateral compression strength of the alumina carrier is greater than 35 kg / cm.

[0032] Through projection electron microscope image observation, the alumina supported catalyst for advanced oxidation treatment of organic wastewater with ozone provided by the present invention is of nanorod type, and the supported heteropolyacid particles are evenly distributed and embedded with the carrier, which can improve the catalyst stability.

[0033] The mass percentage content of each component of the alumina supported catalyst in Examples 1-3 is shown in Table 1:

[0034] Table 1

[0035] Example NiO / % Mn / % Si / % Al2O3 / % 1 4 3 5 88 2 7 3 3 87 3 10 5 6 79

[0036] The method for preparing an alumina-supported catalyst for advanced ozone oxidation treatment of organic wastewater in the present invention comprises the following steps:

[0037] 1) High-temperature inorganic method to prepare alumina carrier with high strength, large specific surface area and suitable pore structure;

[0038] 2) Synthesize heteropolyacid system by template method;

[0039] 3) The alumina carrier obtained in step 1) is subjected to precipitation, impregnation and surface modification with a heteropolyacid system to prepare a catalyst.

[0040] Preferably, silicic acid is added during the synthesis of the alumina carrier in step 1) to prepare carriers with different requirements.

[0041] The alumina supported catalysts of Examples 1-3 were prepared according to the above steps, and then Examples 1-3 were used in the ozone catalytic oxidation experiment of organic wastewater. The organic wastewater and ozone-containing gas were input from the bottom of the riser in the fluidized bed reactor to undergo mass transfer reactions with ozone and organic pollutants.

[0042] The effects of the catalyst after ozone oxidation treatment are shown in Table 2:

[0043] Table 2

[0044]

[0045] It can be seen from the results in Table 2 that the catalyst of the embodiment is more conducive to the removal of COD in organic wastewater, and the COD removal rate can reach 70.6%, with higher catalytic activity.

[0046] The present invention further provides an alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone or an alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone prepared by the preparation method of the alumina supported catalyst for advanced oxidation treatment of organic wastewater by ozone of the present invention and its application in wastewater treatment.

[0047] Examples of the organic wastewater include papermaking organic wastewater, pharmaceutical refractory organic wastewater, and industrial organic amine water.

[0048] The alumina-supported catalyst for advanced oxidation treatment of organic wastewater with ozone obtained by the present invention further improves the performance of catalytic generation of hydroxyl radicals mainly through a novel heteropolyacid active system and a high specific surface area alumina carrier, wherein the developed highly active, stable and weather-resistant heteropolyacid system is combined with a high specific surface area carrier synthesis technology and a loading technology, the obtained catalyst has high stability and high catalytic activity, has excellent catalytic oxidation effect on bio-refractory organic wastewater, can improve ozone utilization, achieve higher COD removal efficiency, the COD removal efficiency can reach 70.6%, and reduce operating costs.

[0049] In order to verify the technical effect of the present invention, the applicant conducted the following COD removal effect test:

[0050] The performance of the catalyst prepared according to the present invention is compared with several existing catalytic means. The catalyst is purchased from commercial catalysts on the market. The catalyst is packaged and placed in organic sewage. Ozone gas is introduced into the lower part of the tank. The results are shown in Table 3:

[0051] Table 3

[0052]

[0053] Based on the above experimental results, it can be concluded that the present invention further improves the performance of catalytic generation of hydroxyl radicals through the novel heteropolyacid active system and high specific surface area alumina carrier modification, which is beneficial to improve catalyst activity, increase ozone utilization rate and reduce operating costs.

[0054] The specific implementation methods described above are only descriptions of the preferred methods 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. An alumina-supported catalyst for advanced oxidation treatment of organic wastewater by ozone, characterized in that: The basic composition of the alumina carrier catalyst is: NiO4-12%, Mn3-5%, Si3-6%, Al2O377-90% by mass ratio; The alumina carrier is modified by a modifier of nickel oxide or a manganese-containing heteropoly acid, wherein the modification treatment is carried out by using a mixed suspension impregnation solution of nickel nitrate with a concentration of 0.1-1.5 mol / l and a manganese-containing heteropoly acid to obtain an advanced oxidation catalyst for ozone of organic wastewater.

2. The catalyst according to claim 1, characterized in that The alumina carrier modification treatment adopts a combined impregnation and adsorption method, urea and ammonia water are used as precipitants, and the pH is adjusted to 10-12, and pure water is used for washing after precipitation.

3. The catalyst according to claim 1, characterized in that The modifier is a mixed oxide of manganese, nickel, silicon and aluminum.

4. The catalyst according to claim 1, characterized in that The alumina carrier has a specific surface area of ​​>25m2 / g and a crystal phase of α-A12O3.

5. The catalyst according to claim 1, characterized in that The lateral compression strength of the alumina carrier is greater than 35 kg / cm.

6. The method for preparing the catalyst according to claim 1, comprising the steps of: 1) Using a high temperature inorganic method to prepare an alumina carrier with high strength, large specific surface area and suitable pore structure; 2) Synthesize heteropolyacid system by template method; 3) The alumina carrier obtained in step (1) is subjected to precipitation, impregnation and surface modification with a heteropolyacid system to prepare a catalyst.

7. The preparation method according to claim 6, characterized in that: Step 1) Silicic acid is added during the synthesis of the alumina carrier to prepare carriers with different requirements.

8. The preparation method according to claim 6, characterized in that: After the carrier is prepared, it is impregnated with nickel nitrate at a concentration of 0.1-1.5 mol / l, loaded with a heteropoly acid, and heated.

9. Use of the alumina supported catalyst treated by ozone advanced oxidation according to any one of claims 1 to 5 or the alumina supported catalyst treated by ozone advanced oxidation obtained by the preparation method according to any one of claims 6 to 8 in organic wastewater treatment.

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