Catalyst for treating saline organic wastewater and its preparation method and application

Abstract

The invention provides a catalyst for treating saline organic wastewater, and a preparation method and application thereof. The preparation method comprises the following steps: preparing a Mn-ZIF-67 precursor, adding Mn-ZIF-67 to a multi-level pore MOR molecular sieve synthesis mother liquor containing an oleophobic modified silicon source, heating and stirring to obtain a gel, adopting a quasi-solid phase crystallization process to prepare an oleophilic multi-level pore CoMn@MOR molecular sieve, and grafting hydrophobic functional groups on the surface thereof to obtain a hydrophobic-oleophilic multi-level pore CoMn@MOR catalyst. The catalyst prepared by the invention can efficiently remove organic matter in saline wastewater, the oleophilic multi-level pore MOR promotes the adsorption of organic matter in the wastewater, the hydrophobic functional groups on the surface inhibit the adsorption of water, and the treatment efficiency of organic matter in the wastewater is improved.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a catalyst for treating salt-containing organic wastewater and a preparation method and application thereof. Background Art

[0002] With the rapid development of the economy, industrial wastewater pollution is becoming more and more serious. The damage to the ecology caused by the entry of a large amount of organic matter into natural water bodies is one of the biggest challenges facing mankind. Saline organic wastewater is organic wastewater containing a certain concentration of inorganic salts. If these organic wastewaters containing high concentrations of inorganic salts are directly discharged without treatment, they will pollute water resources and threaten human life and safety. Therefore, the treatment of saline organic wastewater is very important. Organic wastewater is often treated by microbial methods, but when the concentration of inorganic salts in the wastewater is too high, microorganisms cannot survive. Therefore, it is very important to develop efficient purification technology for saline organic wastewater. Fenton-like catalytic oxidation is an advanced oxidation technology in sewage treatment. It has the characteristics of simple operation, low cost, high degradation efficiency, simple equipment and broad application prospects. The key to traditional Fenton catalytic oxidation technology lies in the catalyst, which is mainly Fe 2+ As a catalyst, it donates electrons to H 2 O 2 ·OH is produced, and the Fe 3+ Can be H 2 O 2 Reduction to Fe 2+ The whole process needs to rely on the addition of ferrous sulfate to promote the reaction, and in the later stage, Fe 3+ Excessive accumulation causes the "iron sludge" phenomenon, which brings secondary pollution, and the pH range of the solution is narrow (3 to 5).

[0003] Heterogeneous catalytic materials for H activation 2 O 2 The generation of ·OH radicals can improve the defects of traditional Fenton catalysts. However, the development of efficient heterogeneous catalysts has always been a challenge in the catalytic oxidation treatment of saline organic wastewater.

[0004] Invention patent CN114405494B discloses a catalyst for deep oxidation of saline organic wastewater, which uses calcium salt as the metal active component. The conventional impregnation method can be used to quickly prepare the catalyst, which can be used for the treatment of saline organic wastewater. Patent CN115025767A discloses a calcium-based porous carbon sphere catalyst for catalytic oxidation treatment of saline organic wastewater, which is composed of calcium oxide supported on a network of porous carbon spheres, mainly based on the cross-linking reaction between sodium alginate solution and calcium ions. However, the interaction between metal and carrier in these two methods is weak, and metal ions are easily precipitated to cause secondary pollution. The homogeneous transition metal ion system has a high activation ability, but has the disadvantages of poor recyclability and easy sludge generation. However, commonly used heterogeneous transition metal oxides and supported nanoparticles and other materials have low metal atom utilization and slow reaction kinetics. Hydrogen bond-assisted pyrolysis is used to prepare heteroatom-modified carbon-based Cu-N 4 Single-atom catalysts. By introducing electron-deficient boron or electron-rich phosphorus into the carbon substrate, the electron density of the Cu center was systematically adjusted. 4 / CB materials have the best catalytic oxidation ability, and their activity is better than most heterogeneous Fenton-like catalysts (Proceedings of the National Academy of Sciences, 2022, Vol. 119, p. e2119492119). So far, many heterogeneous catalysts have been developed for catalytic oxidation treatment of saline organic wastewater, but they are mainly limited to carbon-based nanomaterials and single-atom catalysts, most of which are not stable enough and are not suitable for practical applications. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a catalyst for treating saline organic wastewater and its preparation method and application, confining CoMn bimetallic clusters into the pores of multi-level pore MOR molecular sieves, and the catalyst can effectively remove organic matter in saline organic wastewater.

[0006] The present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a catalyst for treating saline organic wastewater, comprising the following steps:

[0008] S1, preparing Mn-ZIF-67 precursor;

[0009] S2, modifying the silicon source to be lipophilic to obtain an lipophilic silicon source;

[0010] S3, dispersing the lipophilic silicon source in a solvent, sequentially adding a mesoporous template, NaOH, and deionized water, mixing, heating, and stirring, and removing the solvent to obtain a gel;

[0011] S4, adding a certain amount of Mn-ZIF-67 precursor to the gel and stirring, then adding sodium aluminate and MOR seed crystals, heating and stirring, transferring the gel for crystallization, drying, and calcining to obtain CoMn@MOR molecular sieve;

[0012] S5. The CoMn@MOR molecular sieve is hydrophobically modified, washed and separated to obtain the target catalyst.

[0013] First, a Mn-ZIF-67 precursor is prepared. Then, the Mn-ZIF-67 precursor is added to a multi-level porous MOR molecular sieve synthesis mother liquor containing a lipophilic modified silicon source, and heated and stirred to obtain a gel. A quasi-solid phase crystallization process is used to prepare a lipophilic multi-level porous CoMn@MOR molecular sieve. Then, hydrophobic functional groups are grafted on its surface to obtain a hydrophobic-lipophilic multi-level porous CoMn@MOR catalyst.

[0014] The Mn-ZIF-67 precursor and gel are mixed and stirred, and then quasi-solid phase crystallization is used to confine CoMn to the pores of the MOR molecular sieve to form a multi-level pore CoMn@MOR molecular sieve. The multi-level pore CoMn@MOR molecular sieve contains pores of different levels, which can allow organic molecules to enter the interior of the molecular sieve. The lipophilic silicon source used in the gel makes the MOR molecular sieve have multiple lipophilic groups inside. Finally, the surface of the CoMn@MOR molecular sieve is hydrophobically modified to prevent water from entering the pores of the molecular sieve and avoid inhibiting the reaction activity of the CoMn bimetallic cluster sites.

[0015] Further, step S1 comprises: adding a Co source and a Mn source into a solvent and stirring, then adding dimethylimidazole and stirring to form a brown precipitate, and washing and drying the precipitate to obtain a Mn-ZIF-67 precursor.

[0016] Furthermore, the Co source is selected from one of cobalt nitrate, cobalt acetate, cobalt sulfate or cobalt chloride, the Mn source is selected from one of manganese nitrate, manganese sulfate or manganese chloride, and the molar ratio of the Co source to the Mn source is 1:0.1-3; the solvent is methanol, and the drying is drying at 40-80°C for 6-24h.

[0017] Furthermore, step S2 comprises: adding tetraethyl orthosilicate and an oleophilic silane coupling agent into a solvent, stirring, and centrifuging to obtain an oleophilic silicon source.

[0018] Furthermore, the mass ratio of tetraethyl orthosilicate to the oleophilic silane coupling agent is 1:1-5.

[0019] Furthermore, the lipophilic silane coupling agent is selected from one of vinyl trichlorosilane, vinyl trimethoxysilane, aniline methyl trimethoxysilane or chloromethyl triethoxysilane; and the solvent is one of methanol, ethanol or diethyl ether.

[0020] Further, in step S3, the molar ratio of the lipophilic silicon source, the mesoporous template agent, NaOH, and deionized water is 1: 0.05-0.3: 0.05-3: 10-50;

[0021] The mesoporous template agent is one of hexadecyltrimethylammonium bromide, tetraethylammonium hydroxide, polydiallyldimethylammonium chloride or polyacrylic acid, and the solvent is one of water, ethanol or methanol.

[0022] Furthermore, in step S4, the certain amount is a molar ratio of n(Si):n(Co+Mn)=1:0.5-3. n(Si) is the molar content of Si in the gel, and n(Co+Mn) is the sum of the molar contents of Co and Mn in the Mn-ZIF-67 precursor.

[0023] Furthermore, in step S4, sodium aluminate and MOR seeds are added in a molar ratio of n(Si):n(sodium aluminate):n(MOR seeds)=1:0.2~1:0.1~0.7; then a macroporous template is added in a mass ratio of m(SiO2):m(macroporous template)=1:0.01~0.1, and the macroporous template is one of glycerol, lignin, polyurethane foam or alkyl imidazole.

[0024] Furthermore, in step S4, the crystallization is performed by dynamic crystallization at 90-180°C for 12-96 hours and a rotation speed of 10-30 r·min. -1 ; Drying is at 80-100°C; Calcination is at 400-650°C for 3-20h.

[0025] Further, in step S5, the hydrophobic modification is to add the CoMn@MOR molecular sieve to a hydrophobic silane coupling agent and ultrasonically treat it for 3 to 8 hours; the hydrophobic silane coupling agent is one of n-octyltriethoxysilane, tridecafluoro-n-octylsilane, γ-methacryloxypropyltrimethoxysilane or stearic acid;

[0026] The washing adopts one or more of deionized water, methanol or ethanol; the separation is one of centrifugation and suction filtration.

[0027] The present invention also provides a catalyst for treating saline organic wastewater prepared by the above preparation method.

[0028] The present invention also provides a method for treating saline organic wastewater, which comprises loading a catalyst for treating saline organic wastewater into a reactor, introducing saline organic wastewater and adding hydrogen peroxide to carry out reaction treatment;

[0029] Catalyst loading is 200~400g·L -1, reaction conditions: normal pressure, reaction temperature 40-120℃, reaction time 3-24h; wastewater flow rate 5-60mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:0.5~6.0, pH=7.

[0030] When treating salt-containing organic wastewater, the hydrophobic functional groups on the outer surface of the catalyst can inhibit water from entering the pores of the molecular sieve. The multi-level pore molecular sieve allows organic molecules to enter, and the internal lipophilic functional groups can promote the adsorption of organic matter, allowing the organic matter to diffuse to the CoMn bimetallic cluster sites confined by the MOR and be deeply oxidized, thereby improving the treatment efficiency of organic matter in wastewater.

[0031] The present invention has the following beneficial effects:

[0032] 1. The present invention adds a Mn-ZIF-67 precursor to a multi-level porous MOR molecular sieve synthesis mother liquor containing a lipophilic modified silicon source, heats and stirs to obtain a gel, adopts a quasi-solid phase crystallization process to prepare a lipophilic multi-level porous CoMn@MOR molecular sieve, and then grafts hydrophobic functional groups on its surface to obtain a target catalyst, and confines the CoMn bimetallic clusters to the pores of the multi-level porous MOR molecular sieve through appropriate treatment. The prepared catalyst provides favorable structural conditions for removing organic matter in saline organic wastewater.

[0033] 2. The hydrophobic functional groups on the outer surface of the catalyst prepared by the present invention can inhibit water from entering the pores of the molecular sieve, while the internal lipophilic functional groups can promote the adsorption of organic matter, allowing it to diffuse to the CoMn bimetallic cluster sites confined by MOR so that it is deeply oxidized, thereby improving the treatment efficiency of organic matter in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 The XRD spectrum of the catalyst prepared in Example 1 of the present invention;

[0036] Figure 2 The hydrophobic contact angle test of the catalyst prepared in Example 1 of the present invention;

[0037] Figure 3 The lipophilicity contact angle test of the catalyst prepared in Example 1 of the present invention;

[0038] Figure 4is the removal rate of organic matter in wastewater by different catalysts in Examples 1 to 6 of the present invention;

[0039] Figure 5 It is the removal rate of organic matter in wastewater by different catalysts in Comparative Examples 1 to 4 of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The main components of the saline organic wastewater used in the following specific embodiments of the present invention include: sodium chloride, sodium carbonate, sodium sulfate, N-methylsuccinamide, dimethyl phthalate, acetic acid, aminoacetonitrile, and methyl ammonium chloride.

[0042] Example 1

[0043] The steps for preparing the catalyst in this embodiment are:

[0044] S1. Add cobalt nitrate and manganese nitrate to methanol and stir for 1 h, wherein the molar ratio n(Co):n(Mn)=1:0.1, then add 0.2 M dimethylimidazole and stir for 2 h to form a brown precipitate, which is then washed once and dried to obtain a Mn-ZIF-67 precursor;

[0045] S2, adding tetraethyl orthosilicate and vinyltrichlorosilane in a mass ratio of 1:1 into ethanol, stirring for 6 hours, and centrifuging to obtain an oleophilic silicon source;

[0046] S3, dispersing the lipophilic silicon source in an ethanol solution, and then sequentially adding the following in a molar ratio: n(Si):n(hexadecyltrimethylammonium bromide):n(NaOH):n(H 2 O) = 1:0.05:0.05:10, cetyltrimethylammonium bromide, NaOH and deionized water were added, mixed and stirred for 1 hour, and then heated and stirred to remove ethanol to obtain a gel;

[0047] S4, adding Mn-ZIF-67 precursor to the gel in a molar ratio of n(Si):n(Co+Mn)=1:0.5, stirring for 2h; adding sodium aluminate and MOR seed crystals in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.2:0.1 under stirring; then 2):m(glycerol)=1:0.02 Glycerol was added and heated and stirred at a rate of 800r / min for 5h to remove most of the water; the gel was then transferred to a polytetrafluoroethylene-lined crystallization reactor for dynamic crystallization at 90°C for 12h at a speed of 10r·min -1 ; Dry at 80℃; Calcinate at 400℃ for 3h to obtain a multi-level pore CoMn@MOR molecular sieve;

[0048] S5. Add the multi-level pore CoMn@MOR molecular sieve into n-octyltriethoxysilane and ultrasonically treat for 3 hours, then wash with deionized water and centrifuge to obtain the target catalyst.

[0049] The catalyst prepared in Example 1 was characterized by X-ray diffractometer. Figure 1 As shown in the XRD diagram, the catalyst only shows obvious MOR characteristic diffraction peaks, and no CoMn characteristic diffraction peaks appear, indicating that the CoMn bimetallic clusters are confined to the multi-level pore MOR molecular sieve.

[0050] The catalyst prepared in Example 1 was characterized by using contact angle. Figure 2 and Figure 3 As shown in Figure 2, the contact angle test shows that the prepared catalyst has excellent hydrophobic and lipophilic properties.

[0051] The catalyst prepared in Example 1 was used to treat the salt-containing organic wastewater. The catalyst was loaded into a reactor, and the salt-containing organic wastewater was introduced and hydrogen peroxide was added to react. The catalyst was granulated into 20-40 meshes. The catalyst loading amount was 200 g·L -1 ; Reaction temperature: 40℃; Reaction time: 3h; Wastewater flow rate: 5mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:0.5, pH = 7; At normal pressure, the results of organic matter removal in wastewater are as follows Figure 4 shown.

[0052] Example 2

[0053] The steps for preparing the catalyst in this embodiment are:

[0054] S1. Add cobalt acetate and manganese sulfate to methanol and stir for 2 h, wherein the molar ratio n(Co):n(Mn)=1:0.5, then add 0.4 M dimethylimidazole and stir for 4 h to form a brown precipitate, which is then washed twice and dried to obtain a Mn-ZIF-67 precursor;

[0055] S2, adding tetraethyl orthosilicate and vinyltrimethoxysilane in a mass ratio of 1:2 into ethanol, stirring for 8 hours, and centrifuging to obtain an oleophilic silicon source;

[0056] S3, dispersing the lipophilic silicon source in the ethanol solution, and then mixing them in the molar ratio of n(Si):n(tetraethylammonium hydroxide):n(NaOH):n(H 2 O) = 1:0.1:0.1:20, tetraethylammonium hydroxide, NaOH and deionized water were added, mixed and stirred for 2 hours, and then heated and stirred to remove ethanol to obtain a gel;

[0057] S4, adding Mn-ZIF-67 precursor to the gel in a molar ratio of n(Si):n(Co+Mn)=1:1, stirring for 3h; adding sodium aluminate and MOR seed crystals in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.3:0.4 under stirring; then 2 ):m(lignin)=1:0.04. Add lignin and heat and stir at a rate of 800r / min for 10h to remove most of the water; then transfer the gel to a polytetrafluoroethylene-lined crystallization kettle and dynamically crystallize at 100°C for 24h at a speed of 20r·min. -1 ; Dry at 90°C; Calcinate at 500°C for 5h to obtain a multi-level pore CoMn@MOR molecular sieve;

[0058] S5. Add the multi-level pore CoMn@MOR molecular sieve into tridecafluorooctylsilane and ultrasonically treat for 3 hours, wash with formaldehyde, and separate by centrifugation to obtain the target catalyst.

[0059] The catalyst prepared in Example 2 was used to treat the salt-containing organic wastewater. The catalyst was loaded into a reactor, and the salt-containing organic wastewater was introduced and hydrogen peroxide was added to react. The catalyst was granulated into 20-40 meshes. The catalyst loading amount was 300 g·L -1 ; Reaction temperature: 60℃; Reaction time: 10h; Wastewater flow rate: 10mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:1, pH = 7; At normal pressure, the results of organic matter removal in wastewater are as follows Figure 4 shown.

[0060] Example 3

[0061] The steps for preparing the catalyst in this embodiment are:

[0062] S1. Add cobalt sulfate and manganese chloride to methanol and stir for 3 h, wherein the molar ratio n(Co):n(Mn)=1:1, then add 0.4 M dimethylimidazole and stir for 6 h to form a brown precipitate, which is then washed 3 times and dried to obtain a Mn-ZIF-67 precursor;

[0063] S2, adding tetraethyl orthosilicate and aniline methyl trimethoxysilane in a mass ratio of 1:3 into ether, stirring for 10 hours, and centrifuging to obtain an oleophilic silicon source;

[0064] S3, dispersing the lipophilic silicon source in the ethanol solution, and then mixing them in the molar ratio of n(Si):n(polydiallyldimethylammonium chloride):n(NaOH):n(H 2 O) = 1:0.2:0.2:30, add polydiallyldimethylammonium chloride, NaOH and deionized water, mix and stir for 3 hours, then heat and stir, remove ethanol, and obtain a gel;

[0065] S4, adding Mn-ZIF-67 precursor to the gel in a molar ratio of n(Si):n(Co+Mn)=1:2, stirring for 4h; adding sodium aluminate and MOR seed crystals in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.4:0.6 under stirring; then 2 ):m(polyurethane foam)=1:0.03. Add polyurethane foam and heat and stir at a rate of 800r / min for 10h to remove most of the water; then transfer the gel to a polytetrafluoroethylene-lined crystallization kettle for dynamic crystallization at 120°C for 36h at a speed of 10r·min. -1 ; Dry at 95℃; Calcinate at 550℃ for 12h to obtain a multi-level pore CoMn@MOR molecular sieve;

[0066] S5. Add the hierarchical CoMn@MOR molecular sieve into γ-methacryloxypropyltrimethoxysilane and ultrasonically treat for 3 hours, then wash with methanol and separate by centrifugation to obtain the target catalyst.

[0067] The catalyst prepared in Example 3 was used to treat the salt-containing organic wastewater. The catalyst was loaded into a reactor, and the salt-containing organic wastewater was introduced and hydrogen peroxide was added to react. The catalyst was granulated into 20-40 meshes. The catalyst loading amount was 400 g·L -1 ; Reaction temperature: 80℃; Reaction time: 15h; Wastewater flow rate: 20mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:2, pH = 7; At normal pressure, the results of organic matter removal in wastewater are as follows Figure 4 shown.

[0068] Example 4

[0069] The steps for preparing the catalyst in this embodiment are:

[0070] S1. Add cobalt chloride and manganese nitrate to methanol and stir for 4 hours, wherein the molar ratio n(Co):n(Mn)=1:1, then add 0.6M dimethylimidazole and stir for 8 hours to form a brown precipitate, which is then washed 4 times and dried to obtain a Mn-ZIF-67 precursor;

[0071] S2, adding tetraethyl orthosilicate and chloromethyltriethoxysilane in a mass ratio of 1:4 into methanol, stirring for 12 hours, and centrifuging to obtain an oleophilic silicon source;

[0072] S3, dispersing the lipophilic silicon source in methanol solution, and then sequentially mixing in a molar ratio of n(Si):n(polyacrylic acid):n(NaOH):n(H 2 O)=1:0.25:0.25:40, add polyacrylic acid, NaOH and deionized water, mix and stir for 4 hours, then heat and stir to remove methanol to obtain a gel.

[0073] S4, adding Mn-ZIF-67 precursor to the gel in a molar ratio of n(Si):n(Co+Mn)=1:2.5, stirring for 5h; adding sodium aluminate and MOR seed crystals in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.8:0.5 under stirring; then 2 ):m(alkyl imidazole)=1:0.04. Add alkyl imidazole and heat and stir at a rate of 800 r / min for 15 h to remove most of the water; then transfer the gel to a polytetrafluoroethylene-lined crystallization reactor and perform dynamic crystallization at 140°C for 48 h at a speed of 30 r·min. -1 ; Dry at 100°C; Calcinate at 550°C for 15h to obtain a multi-level pore CoMn@MOR molecular sieve;

[0074] S5. Add the multi-level pore CoMn@MOR molecular sieve into stearic acid and ultrasonically treat for 6 hours, then wash with ethanol and centrifuge to obtain the target catalyst.

[0075] The catalyst prepared in Example 4 was used to treat the salt-containing organic wastewater. The catalyst was loaded into a reactor, and the salt-containing organic wastewater was introduced and hydrogen peroxide was added to react. The catalyst was granulated into 20-40 meshes. The catalyst loading was 200 g·L -1 ; Reaction temperature is 100℃; Reaction time is 20h; Wastewater flow rate is 30mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:3, pH = 7; At normal pressure, the results of organic matter removal in wastewater are as follows Figure 4 shown.

[0076] Example 5

[0077] The steps for preparing the catalyst in this embodiment are:

[0078] S1. Add cobalt acetate and manganese chloride to methanol and stir for 2 h, wherein the molar ratio n(Co):n(Mn)=1:2, then add 0.8 M dimethylimidazole and stir for 10 h to form a brown precipitate, which is then washed once and dried to obtain a Mn-ZIF-67 precursor;

[0079] S2, adding tetraethyl orthosilicate and vinyltrimethoxysilane in a mass ratio of 1:1 into diethyl ether, stirring for 24 hours, and centrifuging to obtain an oleophilic silicon source;

[0080] S3, dispersing the lipophilic silicon source in the aqueous solution, and then mixing them in the following molar ratios: n(Si):n(tetraethylammonium hydroxide):n(NaOH):n(H 2 O) = 1:0.1:0.5:10, tetraethylammonium hydroxide, NaOH and deionized water were added, mixed and stirred for 1 hour, and then heated and stirred to remove water to obtain a gel.

[0081] S4, adding Mn-ZIF-67 precursor to the gel in a molar ratio of n(Si):n(Co+Mn)=1:1, stirring for 4h; adding sodium aluminate and MOR seed crystals in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.5:0.4 under stirring; then 2 ):m(lignin)=1:0.06 Add lignin, heat and stir at a rate of 800r / min for 24h to remove most of the water; then transfer the gel to a polytetrafluoroethylene-lined crystallization kettle and dynamically crystallize at 100°C for 72h at a speed of 10r·min -1 ; Dry at 90℃; Calcinate at 600℃ for 5h to obtain a multi-level pore CoMn@MOR molecular sieve;

[0082] S5. Add the multi-level pore CoMn@MOR molecular sieve into tridecafluorooctylsilane and ultrasonically treat for 6 hours, then wash with ethanol and separate by centrifugation to obtain the target catalyst.

[0083] The catalyst prepared in Example 5 was used to treat the salt-containing organic wastewater. The catalyst was loaded into a reactor, and the salt-containing organic wastewater was introduced and hydrogen peroxide was added to react. The catalyst was granulated into 20-40 meshes. The catalyst loading amount was 400 g·L -1 ; Reaction temperature: 80℃; Reaction time: 12h; Wastewater flow rate: 60mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:5, pH = 7; At normal pressure, the results of organic matter removal in wastewater are as follows Figure 4 shown.

[0084] Example 6

[0085] The steps for preparing the catalyst in this embodiment are:

[0086] S1. Add cobalt sulfate and manganese chloride to methanol and stir for 3 h, wherein the molar ratio n(Co):n(Mn)=1:3, then add 1.0 M dimethylimidazole and stir for 6 h to form a brown precipitate, which is then washed 3 times and dried to obtain a Mn-ZIF-67 precursor;

[0087] S2, adding tetraethyl orthosilicate and aniline methyl trimethoxysilane in a mass ratio of 1:3 to ethanol, stirring for 12 hours, and centrifuging to obtain an oleophilic silicon source;

[0088] S3, dispersing the lipophilic silicon source in methanol solution, and then mixing in the following molar ratios: n(Si):n(hexadecyltrimethylammonium bromide):n(NaOH):n(H 2 O)=1:0.2:2:20, cetyltrimethylammonium bromide, NaOH and deionized water were added, mixed and stirred for 3 hours, and then heated and stirred to remove methanol to obtain a gel.

[0089] S4, adding Mn-ZIF-67 precursor to the gel in a molar ratio of n(Si):n(Co+Mn)=1:2, stirring for 5h; adding sodium aluminate and MOR seed crystals in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.3:0.6 under stirring; then 2 ):m(glycerol)=1:0.08 Glycerol was added and heated and stirred at a rate of 800r / min for 20h to remove most of the water; the gel was then transferred to a polytetrafluoroethylene-lined crystallization reactor for dynamic crystallization at 120°C for 96h at a speed of 30r·min -1 ; Dry at 100°C; Calcinate at 650°C for 10h to obtain a multi-level pore CoMn@MOR molecular sieve;

[0090] S5. Add the multi-level pore CoMn@MOR molecular sieve into n-octyltriethoxysilane and ultrasonically treat for 8 hours, then wash with ethanol and centrifuge to obtain the target catalyst.

[0091] The catalyst prepared in Example 6 was used to treat the salt-containing organic wastewater. The catalyst was loaded into a reactor, and the salt-containing organic wastewater was introduced and hydrogen peroxide was added to react. The catalyst was granulated into 20-40 meshes. The catalyst loading amount was 300 g·L -1 ; Reaction temperature is 100℃; Reaction time is 20h; Wastewater flow rate is 30mL·min -1 ; The feed ratio of wastewater to hydrogen peroxide is 1:6, pH = 7; At normal pressure, the results of organic matter removal in wastewater are as follows Figure 4 shown.

[0092] Comparative Example 1

[0093] The Mn-ZIF-67 precursor prepared in Example 1 was used to treat saline organic wastewater under the same test conditions as in Example 1. The results of organic matter removal in the wastewater are as follows: Figure 5 shown.

[0094] Comparative Example 2

[0095] In step S3 of Example 1, no Mn-ZIF-67 precursor is added. The obtained oleophilic multi-level pore MOR is used to treat saline organic wastewater under the same test conditions as in Example 1. The results of organic matter removal in the wastewater are as follows: Figure 5 shown.

[0096] Comparative Example 3

[0097] In Example 1, step S5 is not performed to obtain the oleophilic multi-level porous CoMn@MOR catalyst. The salt-containing organic wastewater is treated under the same test conditions as in Example 1. The results of organic matter removal in the wastewater are as follows: Figure 5 shown.

[0098] Comparative Example 4

[0099] The saline organic wastewater was treated under the same test conditions as in Example 1. No catalyst was added during the treatment process, only hydrogen peroxide was added. The results of organic matter removal in the wastewater are as follows: Figure 5 shown.

[0100] from Figure 4 , Figure 5 It can be seen that in Comparative Examples 2 and 4, only hydrogen peroxide has a certain removal effect on organic wastewater, and the removal effect of organic matter is poor. In Comparative Example 1, the CoMn bimetallic cluster site of Mn-ZIF-67 is directly in contact with the wastewater, and water will compete with organic matter for active sites, thereby affecting the removal effect. In Comparative Example 3, since the surface of the multi-level pore CoMn@MOR molecular sieve is not hydrophobically modified, part of the water will still enter the molecular sieve and affect the removal efficiency of organic matter. The hydrophobic functional groups on the outer surface of the catalyst prepared in Examples 1 to 6 of the present invention can inhibit water from entering the pores of the molecular sieve, while the internal lipophilic functional groups can promote the adsorption of organic matter, causing it to diffuse to the CoMn bimetallic cluster site confined by MOR so that it is deeply oxidized, thereby improving the treatment efficiency of organic matter in wastewater, and the removal rate of organic matter in wastewater can reach a very high level.

[0101] The invention first prepares a Mn-ZIF-67 precursor, then adds the Mn-ZIF-67 precursor into a multi-level porous MOR molecular sieve synthesis mother liquor containing an oleophilic modified silicon source, heats and stirs to obtain a gel, adopts a quasi-solid phase crystallization process to prepare an oleophilic multi-level porous CoMn@MOR molecular sieve, and then grafts a hydrophobic functional group on the surface thereof to obtain a hydrophobic-oleophilic multi-level porous CoMn@MOR catalyst. The catalyst prepared by the invention can efficiently remove organic matter in saline wastewater, the oleophilic multi-level porous MOR promotes the adsorption of organic matter in the wastewater, and the hydrophobic functional group on the surface inhibits the adsorption of water, thereby improving the treatment efficiency of organic matter in the wastewater.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for treating saline organic wastewater, characterized in that: The following steps are involved: S1. Preparation of Mn-ZIF-67 precursor: adding Co source and Mn source to a solvent and stirring, then adding dimethylimidazole and stirring to form a brown precipitate, washing and drying the precipitate to obtain a Mn-ZIF-67 precursor; S2, modifying the silicon source to be lipophilic to obtain an lipophilic silicon source; S3, dispersing the lipophilic silicon source in a solvent, sequentially adding a mesoporous template, NaOH, and deionized water, mixing, heating, and stirring, and removing the solvent to obtain a gel; S4, adding a certain amount of Mn-ZIF-67 precursor to the gel and stirring, then adding sodium aluminate and MOR seed crystals, heating and stirring, transferring the gel for crystallization, drying, and calcining to obtain CoMn@MOR molecular sieve; in step S4, the certain amount is a molar ratio of n(Si):n(Co+Mn)=1:0.5~3; sodium aluminate and MOR seed crystals are added in a molar ratio of n(Si):n(sodium aluminate):n(MOR seed crystal)=1:0.2~1:0.1~0.7; then a macroporous template agent is added at a mass ratio of m(SiO2):m(macroporous template agent)=1:0.01~0.1, the macroporous template agent is one of glycerol, lignin, polyurethane foam or alkyl imidazole, and the crystallization is a dynamic crystallization at 90~180℃ for 12~96h, and a rotation speed of 10~30r·min -1 ; Drying is performed at 80-100°C; Calcination is performed at 400-650°C for 3-20h; S5. The CoMn@MOR molecular sieve is hydrophobically modified, washed and separated to obtain the catalyst.

2. The method for preparing a catalyst for treating saline organic wastewater according to claim 1, characterized in that: The Co source is selected from one of cobalt nitrate, cobalt acetate, cobalt sulfate or cobalt chloride, the Mn source is selected from one of manganese nitrate, manganese sulfate or manganese chloride, and the molar ratio of the Co source to the Mn source is 1:0.1-3; the solvent is methanol, and the drying is drying at 40-80°C for 6-24h.

3. The method for preparing a catalyst for treating saline organic wastewater according to claim 1, characterized in that: Step S2 comprises: adding tetraethyl orthosilicate and an oleophilic silane coupling agent into a solvent, stirring, and centrifuging to obtain an oleophilic silicon source; the mass ratio of the tetraethyl orthosilicate to the oleophilic silane coupling agent is 1:1-5.

4. The method for preparing a catalyst for treating saline organic wastewater according to claim 3, characterized in that: The lipophilic silane coupling agent is selected from one of vinyl trichlorosilane, vinyl trimethoxysilane, aniline methyl trimethoxysilane or chloromethyl triethoxysilane; and the solvent is one of methanol, ethanol or ether.

5. The method for preparing a catalyst for treating saline organic wastewater according to claim 1, characterized in that: In step S3, the molar ratio of the lipophilic silicon source, the mesoporous template, NaOH, and deionized water is 1:0.05-0.3:0.05-3:10-50, the mesoporous template is one of hexadecyltrimethylammonium bromide, tetraethylammonium hydroxide, polydiallyldimethylammonium chloride or polyacrylic acid, and the solvent is one of water, ethanol or methanol.

6. The method for preparing a catalyst for treating saline organic wastewater according to claim 1, characterized in that: In step S5, the hydrophobic modification is to add the CoMn@MOR molecular sieve to a hydrophobic silane coupling agent and ultrasonically treat it for 3 to 8 hours; the hydrophobic silane coupling agent is one of n-octyltriethoxysilane, tridecafluoro-n-octylsilane, γ-methacryloxypropyltrimethoxysilane or stearic acid; The washing is performed by one or more of deionized water, methanol and ethanol; the separation is performed by one of centrifugation and suction filtration.

Images