Method for modifying a silicotitanium molecular sieve

Abstract

The present application relates to the field of molecular sieve preparation, and discloses a modification method of titanium silicalite molecular sieve, which comprises the following steps: 1) mixing titanium silicalite molecular sieve, a modifier and water to obtain a mixture; 2) performing hydrothermal modification treatment on the mixture to obtain a hydrothermal modification treatment product; 3) performing solid-liquid separation on the hydrothermal modification treatment product to obtain a solid phase and a liquid phase; 4) performing washing, drying and first calcination on the solid phase to obtain modified titanium silicalite molecular sieve; and 5) contacting the liquid phase and / or washing liquid obtained by washing with nanopore material, wherein the specific surface area and pore size of the nanopore material are larger than those of the modified titanium silicalite molecular sieve. The method provided by the present application can greatly reduce the COD value of waste liquid generated in the modification process of titanium silicalite molecular sieve, and the modified titanium silicalite molecular sieve obtained by the method has excellent catalytic performance.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation, and more specifically to a method for modifying titanium-silicon molecular sieves. Background Technology

[0002] Titanium silicate molecular sieves are commonly used catalysts in chemical production, especially in petroleum refining and petrochemical industries, where they show great promise. Among them, TS-1 molecular sieve is a novel titanium silicate molecular sieve with excellent catalytic selective oxidation performance, formed by introducing the transition metal element titanium into a molecular sieve framework with a ZSM-5 structure. TS-1 not only possesses the catalytic oxidation properties of titanium but also the shape selectivity and excellent stability of ZSM-5 molecular sieves, and has been successfully industrially applied in the process of catalytic ammonia oxidation of cyclohexanone to prepare cyclohexanone oxime.

[0003] Currently, in order to further improve the reactivity of titanium-silicon molecular sieves, modifiers containing organic matter are usually used to modify them. During the modification process, due to reasons such as the modifier not being fully introduced into the molecular sieve channels and remaining in the synthesis liquid, a large amount of waste liquid containing organic amines, alcohols, etc. is generated. The COD value of such waste liquid can be as high as 10,000 mg / L or more, which has a strong toxic effect on the ecological environment and cannot be directly discharged. However, no effective and low-cost treatment method has been found yet. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of difficult treatment of high COD waste liquid during the modification process of titanium-silicon molecular sieves in the prior art, and to provide a method for modifying titanium-silicon molecular sieves. By using the method described in this invention, the COD value in the waste liquid generated during the modification process of titanium-silicon molecular sieves can be significantly reduced, and the modified titanium-silicon molecular sieve obtained by this method has excellent catalytic performance.

[0005] To achieve the above objectives, the present invention provides a method for modifying titanium-silicon molecular sieves, the method comprising:

[0006] 1) Mix the titanium-silicon molecular sieve, modifier, and water to obtain a mixture;

[0007] 2) The mixture obtained in step 1) is subjected to hydrothermal modification treatment to obtain the hydrothermally modified product;

[0008] 3) The hydrothermal modification product obtained in step 2) is subjected to solid-liquid separation to obtain a solid phase and a liquid phase;

[0009] 4) The solid phase obtained in step 3) is washed, dried and subjected to a first calcination to obtain the modified titanium-silicon molecular sieve;

[0010] 5) Contact the liquid phase obtained in step 3) and / or the washing solution obtained in step 4) with the nanoporous material.

[0011] The modifier contains an alkaline organic modifier, the specific surface area of ​​the nanoporous material is greater than that of the titanium-silicon molecular sieve, and the pore size of the nanoporous material is greater than that of the titanium-silicon molecular sieve.

[0012] Preferably, in step 1), the modifier is an alkaline organic modifier or a mixture of an alkaline organic modifier and an alkaline inorganic modifier; more preferably, it is an alkaline organic modifier.

[0013] Preferably, the alkaline inorganic modifier is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, and barium hydroxide.

[0014] Preferably, the alkaline organic modifier is selected from one or more of urea, quaternary ammonium compounds, fatty amine compounds, and alcoholic amine compounds.

[0015] Preferably, the general formula of the quaternary ammonium base compound is (R 1 )4NOH, where R 1 It is an alkyl group having 1-4 carbon atoms.

[0016] Preferably, the quaternary ammonium base compound is tetrapropylammonium hydroxide.

[0017] Preferably, the general formula of the fatty amine compound is R. 2 (NH2) n , where R 2 It is an alkyl group having 1-6 carbon atoms or an alkylene group having 1-6 carbon atoms, where n is 1 or 2.

[0018] Preferably, the fatty amine compound is selected from one or more of ethylamine, n-butylamine, butanediamine, and hexamethylenediamine.

[0019] Preferably, the general formula of the alkanolamine compound is (HOR) 3 ) m NH (3-m) , where R 3 It is an alkyl group having 1 to 4 carbon atoms, where m is 1, 2 or 3.

[0020] Preferably, the alkanolamine compound is selected from one or more of monoethanolamine, diethanolamine, and triethanolamine.

[0021] Preferably, in step 1), the weight ratio of the titanium silicate molecular sieve, the modifier, and the water is 100:(0.1-10):(200-5000); more preferably, it is 100:(0.5-5):(300-1000).

[0022] Preferably, in step 2), the conditions for the hydrothermal modification treatment include: a temperature of 120-200℃ and a time of 2-48h; more preferably, the conditions for the hydrothermal modification treatment include: a temperature of 140-180℃ and a time of 4-24h.

[0023] Preferably, in step 4), the conditions for the first roasting include: a temperature of 300-700℃ and a time of 0.5-6h; more preferably, the conditions for the first roasting include: a temperature of 400-600℃ and a time of 1-3h.

[0024] Preferably, in step 5), the nanoporous material is one or more of Y-type molecular sieves, β-type molecular sieves, and mesoporous molecular sieves.

[0025] Preferably, the Y-type molecular sieve is one or more of NaY molecular sieve, NH4Y molecular sieve, HY molecular sieve, PHY molecular sieve, USY molecular sieve and ReY molecular sieve.

[0026] Preferably, the β-type molecular sieve is a Naβ molecular sieve and / or an Hβ molecular sieve.

[0027] Preferably, the mesoporous molecular sieve is one or more of SBA-15 mesoporous molecular sieve, SBA-1 mesoporous molecular sieve, M41S, MCM-22 molecular sieve, and MCM-68 molecular sieve.

[0028] More preferably, the nanoporous material is one or more of SBA-15 mesoporous molecular sieve, HY molecular sieve, USY molecular sieve and PHY molecular sieve; even more preferably, the nanoporous material is SBA-15 mesoporous molecular sieve and / or HY molecular sieve.

[0029] Preferably, in step 5), the weight ratio of the liquid phase obtained in step 3) and / or the washing liquid obtained in step 4) to the nanoporous material is 1-100:1; more preferably 1-50:1; and particularly preferably 5-10:1.

[0030] Preferably, in step 5), the contact conditions include: a temperature of 20-100℃ and a time of less than 5 hours; more preferably, in step 5), the contact conditions include: a temperature of 20-80℃ and a time of 10-120 minutes; even more preferably, in step 5), the contact conditions include: a temperature of 30-60℃ and a time of 20-60 minutes.

[0031] Preferably, the specific surface area of ​​the nanoporous material is 20-200% larger than that of the titanium-silicon molecular sieve, more preferably 30-100% larger.

[0032] Preferably, the pore size of the nanoporous material is 20-2500% larger than that of the titanium-silicon molecular sieve, more preferably 40-1000% larger.

[0033] Preferably, the modification method further includes a step of second calcining the nanoporous material after contact in step 5).

[0034] Preferably, the conditions for the second calcination include: a temperature of 400-700℃ and a time of 1-6h; more preferably, the conditions for the second calcination include: a temperature of 500-600℃ and a time of 2-4h.

[0035] In addition, the technical solution in this invention enables impurities in the waste liquid generated during the modification of titanium-silicon molecular sieves to be adsorbed by nanoporous materials, thereby significantly reducing the COD value of the waste liquid generated during the modification of titanium-silicon molecular sieves.

[0036] By employing the technical solution of this invention, the COD value in the waste liquid can be reduced to below 50 mg / L, thereby enabling direct discharge.

[0037] On the other hand, the titanium-silicon molecular sieve modified by the method described in this invention possesses excellent catalytic performance (e.g., reaction conversion rate and selectivity) and activity period. Furthermore, by calcining the nanoporous material after contact with the waste liquid, COD substances can be converted into carbon dioxide and water at high temperatures, achieving harmless treatment. The calcined nanoporous material can also be reused, significantly reducing the treatment cost of the titanium-silicon molecular sieve waste liquid.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0039] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0040] This invention provides a method for modifying titanium-silicon molecular sieves, wherein the method includes:

[0041] 1) Mix the titanium-silicon molecular sieve, modifier, and water to obtain a mixture;

[0042] 2) The mixture obtained in step 1) is subjected to hydrothermal modification treatment to obtain the hydrothermally modified product;

[0043] 3) The hydrothermal modification product obtained in step 2) is subjected to solid-liquid separation to obtain a solid phase and a liquid phase;

[0044] 4) The solid phase obtained in step 3) is washed, dried and subjected to a first calcination to obtain the modified titanium-silicon molecular sieve;

[0045] 5) Contact the liquid phase obtained in step 3) and / or the washing solution obtained in step 4) with the nanoporous material.

[0046] The modifier contains an alkaline organic modifier, the specific surface area of ​​the nanoporous material is greater than that of the titanium-silicon molecular sieve, and the pore size of the nanoporous material is greater than that of the titanium-silicon molecular sieve.

[0047] According to the present invention, a nanoporous material with a specific surface area and pore size larger than that of titanium-silicon molecular sieve is used to contact the waste liquid generated during the modification process of titanium-silicon molecular sieve, thereby significantly reducing the COD value of the waste liquid in a short period of time.

[0048] In this invention, the waste liquid refers to the mother liquor and / or washing liquid generated during the modification process of titanium-silicon molecular sieves. The mother liquor is the liquid phase obtained after solid-liquid separation of the hydrothermal modification product in the method of this invention, and the washing liquid is the washing liquid generated by washing the solid phase obtained after solid-liquid separation of the hydrothermal modification product in the method of this invention.

[0049] In this invention, there is no particular limitation on the source of the titanium-silicon molecular sieve. It can be prepared by conventional methods in the art or commercially available.

[0050] For example, the titanium-silicon molecular sieve can be prepared by the following method:

[0051] 1) Mix the silicon source, titanium source, template agent, and water to obtain a mixture;

[0052] 2) The mixture obtained in step 1) is subjected to crystallization treatment to obtain a crystallized product;

[0053] 3) The crystallized product obtained in step 2) is subjected to solid-liquid separation to obtain a solid phase;

[0054] 4) The solid phase obtained in step 3) is washed, dried and calcined.

[0055] The silicon source, titanium source, template agent, etc., can all be conventional choices in the field.

[0056] The silicon source may be selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate.

[0057] The titanium source may be selected from one or more of TiCl4, Ti(SO4)2, TiOCl2, titanium hydroxide, titanium oxide, titanium nitrate, titanium phosphate, tetrapropyl titanate, tetrabutyl titanate, and tetraethyl titanate.

[0058] The template agent may be selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, tetrapropylammonium hydroxide, ethylamine, n-butylamine, butanediamine, ethanolamine, diethanolamine, and triethanolamine.

[0059] The mass ratio of the silicon source, titanium source, template agent and water can be, for example, 100:(0.2-5):(1-20):(250-2500).

[0060] The conditions for the crystallization treatment may include, for example, a temperature of 140-200°C and a time of 12-96 hours.

[0061] The roasting conditions may include, for example, a temperature of 300-800℃ and a time of 0.5-12h.

[0062] The preparation method of titanium-silicon molecular sieves is a conventional method in this field and will not be described here.

[0063] In this invention, there are no particular limitations on the modifier, as long as it contains an alkaline organic modifier and can modify the titanium-silicon molecular sieve to improve its catalytic performance.

[0064] The modifier may be, for example, various alkaline organic modifiers commonly used in the art, or a mixture of various alkaline organic modifiers and alkaline inorganic modifiers commonly used in the art, preferably an alkaline organic modifier.

[0065] The alkaline inorganic modifier may be selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, and barium hydroxide.

[0066] The alkaline organic modifier may be selected from one or more of urea, quaternary ammonium compounds, fatty amine compounds, and alkanolamine compounds.

[0067] The quaternary ammonium base compound can be any of the various organic quaternary ammonium bases commonly used in the art, and the general formula of the quaternary ammonium base compound can be (R 1 )4NOH, where R 1 Alkyl groups having 1-4 carbon atoms, for example, R 1 It can be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl, etc.

[0068] Preferably, the quaternary ammonium alkali compound is tetrapropylammonium hydroxide, which can further ensure the performance of the modified titanium-silicon molecular sieve.

[0069] In this invention, the aliphatic amine compound can be any of the aliphatic amine compounds conventional in the art, without any particular limitation. The aliphatic amine compound can be a compound formed by replacing at least one hydrogen atom in various NH3 groups with an aliphatic hydrocarbon group (preferably an alkyl group).

[0070] The general formula of the fatty amine compound can be R 2 (NH2) n , where R 2 It is an alkyl group having 1-6 carbon atoms or an alkylene group having 1-6 carbon atoms, where n is 1 or 2.

[0071] When n is 1, the R 2 It is an alkyl group having 1-6 carbon atoms, in which case, the R 2 It can be a C1-C6 straight-chain alkyl group or a C3-C6 branched alkyl group. Specifically, the R... 2 It can be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl, or n-hexyl, etc.

[0072] When n is 2, the R 2 It is an alkylene group having 1-6 carbon atoms, in which case, the R 2 It can be a C1-C6 straight-chain alkylene or a C3-C6 branched alkylene, specifically, the R 2 It can be methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene, etc.

[0073] Preferably, the fatty amine compound is selected from one or more of ethylamine, n-butylamine, butanediamine, and hexamethylenediamine.

[0074] The alkanolamine compound can be any of the alkanolamine compounds commonly used in the art, and can be a compound formed by replacing at least one hydrogen atom in various NH3 groups with a hydroxyl-containing aliphatic hydrocarbon group (preferably alkyl).

[0075] The general formula of the alkanolamine compound can be (HOR) 3 ) m NH (3-m) , where R 3 It is an alkyl group having 1-4 carbon atoms, where m is 1, 2, or 3. Specifically, for example, R 4 It can be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl, etc.

[0076] Preferably, the alkanolamine compound is selected from one or more of monoethanolamine, diethanolamine, and triethanolamine.

[0077] Furthermore, in step 1) of the present invention, there are no particular limitations on the method and order of mixing the titanium silicon molecular sieve, the modifier and water. The mixing can be carried out in accordance with conventional mixing methods and orders in the art, until the substances are mixed.

[0078] In step 1) of this invention, there are no particular limitations on the amounts of the titanium-silicon molecular sieve, the modifier, and the water, as long as the modification of the titanium-silicon molecular sieve can be achieved, which can be a conventional choice in the art. For example, the weight ratio of the titanium-silicon molecular sieve, the modifier, and the water is 100:(0.1-10):(200-5000); preferably 100:(0.5-5):(300-1000). This can further improve the catalytic performance of the modified titanium-silicon molecular sieve.

[0079] Next, in step 2), the mixture obtained in step 1) is subjected to hydrothermal modification treatment to obtain the hydrothermally modified product.

[0080] In this invention, there are no particular limitations on the conditions for the hydrothermal modification treatment. For example, the conditions may include a temperature of 120-200℃ and a time of 2-48 hours; preferably, the conditions may include a temperature of 140-180℃ and a time of 4-24 hours. By performing the hydrothermal modification treatment under the above conditions, the modification effect can be further guaranteed, and the performance of the modified titanium-silicon molecular sieve can be improved.

[0081] According to the present invention, after the hydrothermal modification treatment, step 3) is performed, that is, the hydrothermal modification product is subjected to solid-liquid separation to obtain a solid phase and a liquid phase.

[0082] In this invention, there is no particular limitation on the method for solid-liquid separation, and various methods conventionally used in the art for solid-liquid separation can be employed. For example, plate and frame filtration, tank washing, inorganic ceramic membrane filtration, belt filter filtration, and other methods can be used, as long as the product obtained from the crystallization treatment can be separated into solid and liquid components. Further details will not be elaborated here.

[0083] According to the present invention, in step 4), the solid phase obtained by the solid-liquid separation is further washed, dried and subjected to a first calcination to obtain the modified titanium-silicon molecular sieve.

[0084] In this invention, the washing process is a conventional operation in the field, and the method is not particularly limited, so it will not be described in detail here.

[0085] In this invention, in order to remove the residual moisture after washing, the obtained solid phase is further dried. The drying conditions are not particularly limited. For example, the drying temperature can be 80-150℃ and the drying time can be 0.5-24h; preferably, the drying temperature is 110-130℃ and the drying time is 1-8h.

[0086] Next, the dried product undergoes a first calcination. The conditions for the first calcination are not particularly limited; the temperature can be 300-700℃ and the time can be 0.5-6 hours. Preferably, the conditions for the first calcination include a temperature of 400-600℃ and a time of 1-3 hours. By performing the first calcination under these conditions, the quality of the modified titanium-silicon molecular sieve can be further guaranteed, and its catalytic performance can be improved.

[0087] In this invention, the various substances remaining in the liquid phase obtained from the solid-liquid separation and / or the washing liquid obtained from the above washing process result in a waste liquid with a considerably high COD value, thus making it impossible to discharge directly.

[0088] According to the present invention, by contacting the liquid phase obtained from the solid-liquid separation and / or the washing liquid obtained from the above washing with the nanoporous material, the COD in the waste liquid can be removed, so that the resulting waste liquid meets the emission standards.

[0089] The specific surface area and pore size of the nanoporous material are both greater than those of the modified titanium-silicon molecular sieve.

[0090] According to the present invention, preferably, the specific surface area of ​​the nanoporous material is 20-200% larger than that of the modified titanium-silicon molecular sieve; more preferably, the specific surface area of ​​the nanoporous material is 30-100% larger than that of the modified titanium-silicon molecular sieve.

[0091] Preferably, the pore size of the nanoporous material is 20-2500% larger than that of the modified titanium-silicon molecular sieve; more preferably, the pore size of the nanoporous material is 40-1000% larger than that of the modified titanium-silicon molecular sieve.

[0092] In this invention, the nanoporous material can be, for example, one or more of the following: Y-type molecular sieve, β-type molecular sieve, and mesoporous molecular sieve, in which both the specific surface area and pore size are larger than those of the modified titanium-silicon molecules.

[0093] The Y-type molecular sieve can be selected from one or more of NaY molecular sieve, NH4Y molecular sieve, HY molecular sieve, PHY molecular sieve, USY molecular sieve and ReY molecular sieve, preferably HY molecular sieve and / or PHY molecular sieve.

[0094] The β-type molecular sieve can be selected from, for example, Naβ molecular sieve and / or Hβ molecular sieve, preferably Hβ molecular sieve.

[0095] The mesoporous molecular sieve may be selected from one or more of SBA-15 mesoporous molecular sieve, SBA-1 mesoporous molecular sieve, M41S mesoporous molecular sieve, MCM-22 molecular sieve and MCM-68 molecular sieve, with SBA-15 mesoporous molecular sieve being preferred.

[0096] In this invention, preferably, the nanoporous material is one or more of SBA-15 mesoporous molecular sieve, HY molecular sieve, USY molecular sieve and PHY molecular sieve; more preferably, it is SBA-15 mesoporous molecular sieve and / or HY molecular sieve.

[0097] The aforementioned nanoporous material can strongly adsorb impurities in the waste liquid, thereby significantly reducing the COD value of the waste liquid.

[0098] According to the present invention, during the contact, the total amount of the liquid phase and / or the washing liquid to the mass ratio of the nanoporous material can vary within a certain range. If the COD value of the waste liquid (the liquid phase and / or the washing liquid) is high, the amount of the nanoporous material can be appropriately increased; if the COD value of the waste liquid is low, the amount of the nanoporous material can be appropriately reduced.

[0099] The weight ratio of the liquid phase and / or the washing liquid to the nanoporous material can be 1-100:1; preferably, the weight ratio of the liquid phase and / or the washing liquid to the nanoporous material can be 1-50:1; more preferably, the weight ratio of the liquid phase and / or the washing liquid to the nanoporous material can be 5-10:1.

[0100] Furthermore, in this invention, the contact conditions may include: a temperature of 20-100°C and a time of less than 5 hours; preferably, the contact conditions include: a temperature of 20-80°C and a time of 10-120 minutes; more preferably, the contact conditions include: a temperature of 30-60°C and a time of 20-60 minutes. Contacting the liquid phase and / or the washing liquid with the nanoporous material under the above conditions can significantly reduce the COD value in the waste liquid.

[0101] According to the present invention, if the COD value of the obtained waste liquid is high, or the amount of waste liquid to be treated is large, a multi-stage contact method can also be used.

[0102] In this invention, the multi-stage contact refers to the process of first contacting the waste liquid with the nanoporous material, and then continuing to contact the waste liquid with the nanoporous material a second time, a third time, and so on, until the emission standards are met.

[0103] Furthermore, in this invention, if the COD value of the obtained waste liquid is low, after contacting the waste liquid with the nanoporous material described in this invention, the nanoporous material retains strong adsorption properties after contact. Therefore, the nanoporous material after the first contact can be further contacted with the next batch of waste liquid to be treated, and so on. This can improve the utilization rate of the nanoporous material, thereby further reducing treatment costs and improving economic efficiency.

[0104] In addition, in this invention, after the nanoporous material adsorbs various organic impurities after contact, it can be rendered harmless and recycled through a second calcination.

[0105] Specifically, the nanoporous material that has come into contact with the waste liquid in step 5) can first be dried. The drying process is not particularly limited; for example, flash drying can be used. Then, the nanoporous material is subjected to a second calcination, thereby converting the adsorbed impurities into carbon dioxide and water through high-temperature calcination, achieving harmless treatment and restoring the adsorption capacity of the nanoporous material.

[0106] According to the present invention, the conditions for the second calcination are not particularly limited. For example, the conditions for the second calcination may include a temperature of 400-700°C and a time of 1-6 hours; preferably, the conditions for the second calcination include a temperature of 500-600°C and a time of 2-4 hours.

[0107] Therefore, after the second calcination, impurities in the nanoporous material can be removed, and the nanoporous material after the second calcination can continue to contact the waste liquid to remove COD from the waste liquid, thereby achieving recycling.

[0108] The present invention will now be described in detail through examples and comparative examples.

[0109] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available products.

[0110] Preparation Example

[0111] The titanium-silicon molecular sieves used in the following examples and comparative examples were prepared according to the following methods:

[0112] 1) Tetraethyl orthosilicate, titanium isopropoxide, tetrapropylammonium hydroxide and water are mixed in a mass ratio of 100:2:10:500 to obtain a mixture;

[0113] 2) After the mixture was placed at 90°C for 12 hours, it was transferred to a stainless steel sealed reactor and crystallized at 170°C for 48 hours to obtain the crystallized product.

[0114] 3) Filter the crystallization product to obtain a solid phase;

[0115] 4) The solid phase was thoroughly washed and dried at 110°C for 1 hour, and then calcined at 550°C for 3 hours to obtain titanium silicate molecular sieve (by measuring its X-ray diffraction pattern, it can be determined that it is a titanium silicate molecular sieve with MFI structure).

[0116] The specific surface area of ​​the obtained titanium-silicon molecular sieve is 415 m². 2 / g, with a pore size of 0.55nm.

[0117] Example 1

[0118] 1) Mix titanium silicate molecular sieve, tetrapropylammonium hydroxide and water in a mass ratio of 100:2:500 to obtain a mixture;

[0119] 2) The mixture was transferred to a stainless steel sealed reactor and hydrothermally modified at 170°C for 24 hours to obtain the hydrothermally modified product.

[0120] 3) The hydrothermal modification product is filtered to obtain a solid phase and a liquid phase;

[0121] 4) The solid phase was washed and dried at 110°C for 1 hour, and then calcined at 550°C for 3 hours to obtain the modified titanium-silicon molecular sieve, denoted as S1.

[0122] The specific surface area of ​​S1 was measured to be 438 m². 2 / g, pore size 0.55nm, pore volume 0.34cm³ 3 / g.

[0123] 5) The liquid phase obtained from filtering in step 3) is mixed with SBA-15 mesoporous molecular sieve (specific surface area of ​​730 m²). 2 The liquid phase (S1) was contacted with a pore size of 6.4 nm (g), wherein the weight ratio of the liquid phase to S1 was 5:1, the contact time was 30 min, and the contact temperature was 40 °C. The COD values ​​of the resulting liquid phase after contact are shown in Table 1.

[0124] Example 2

[0125] The procedure is carried out according to the method of Example 1, except that...

[0126] In step 5), the liquid phase is reacted with HY molecular sieve (specific surface area of ​​600 m²). 2 Contact was performed using a pore size of 0.75 nm (g), with the contact conditions remaining unchanged.

[0127] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0128] Example 3

[0129] The procedure is carried out according to the method of Example 1, except that...

[0130] In step 5), the contact time is 30 minutes and the contact temperature is 20°C.

[0131] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0132] Example 4

[0133] The procedure is carried out according to the method of Example 1, except that...

[0134] In step 5), the mass ratio of the liquid phase to the SBA-15 mesoporous molecular sieve is 10:1.

[0135] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0136] Example 5

[0137] The procedure is carried out according to the method of Example 1, except that...

[0138] In step 5), the mass ratio of the liquid phase to the SBA-15 mesoporous molecular sieve is 50:1.

[0139] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0140] Example 6

[0141] The procedure is carried out according to the method of Example 1, except that...

[0142] In step 5), the liquid phase is reacted with Hβ molecular sieve (specific surface area of ​​650 m²). 2 Contact was performed using a pore size of 0.7 nm (g), with the contact conditions remaining unchanged.

[0143] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0144] Example 7

[0145] The procedure is carried out according to the method of Example 1, except that...

[0146] In step 5), the liquid phase is reacted with NaY molecular sieve (specific surface area of ​​580 m²). 2 Contact was performed using a pore size of 0.76 nm (g), with the contact conditions remaining unchanged.

[0147] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0148] Comparative Example 1

[0149] The procedure is carried out according to the method of Example 1, except that...

[0150] The liquid phase is not subjected to the contact treatment in step 5).

[0151] The COD values ​​in the liquid phase are shown in Table 1.

[0152] Comparative Example 2

[0153] The procedure is carried out according to the method of Example 1, except that...

[0154] In step 5), the liquid phase is reacted with ZSM-22 molecular sieve (specific surface area of ​​278 m²). 2 Contact was performed using a pore size of 0.5 nm (g), with the contact conditions remaining unchanged.

[0155] The COD values ​​in the liquid phase obtained after contact are shown in Table 1.

[0156] Table 1

[0157]

[0158] As can be seen from the results in Table 1, when the waste liquid generated during the modification of titanium-silicon molecular sieves is contacted with the nanoporous material using the technical solution of the present invention, the COD value is significantly reduced.

[0159] Test case

[0160] This test example is used to test the application of the titanium-silicon molecular sieve prepared in the preparation example and the modified titanium-silicon molecular sieve obtained in Example 1 as a catalyst in the hydroxylation reaction of phenol.

[0161] The reaction was carried out in a 500ml three-necked flask, with magnetic stirring and heating in an oil bath.

[0162] The process parameters are as follows: H2O2:phenol (molar ratio) = 1:3, acetone:phenol (weight ratio) = 4:5, catalyst dosage is 5% by weight, reaction time is 120 min, reaction temperature is 65℃, and reaction pressure is atmospheric pressure.

[0163] The reaction products were quantitatively analyzed by gas chromatography. Based on this analysis, the phenol conversion rate and hydroquinone selectivity were calculated using the following formulas:

[0164] Phenol conversion rate (%) = [(molar amount of added phenol - molar amount of unreacted phenol) / molar amount of added phenol] × 100%.

[0165] Hydroquinone selectivity (%) = [molar amount of hydroquinone produced in the reaction / (molar amount of phenol added - molar amount of unreacted phenol)] × 100%.

[0166] The above test was repeated 5 times, and the calculated average conversion rate of phenol and the selectivity of hydroquinone are shown in Table 2.

[0167] Table 2

[0168] serial number Average conversion rate of phenol, % Average selectivity of hydroquinone, % Preparation Example 20.1 90.3 Example 1 24.5 96.9

[0169] As can be seen from Table 2, when the modified titanium-silicon molecular sieve obtained by the method of the present invention is used as a catalyst, its catalytic effect is far superior to that of the unmodified titanium-silicon molecular sieve in the preparation example.

[0170] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for modifying titanium-silicon molecular sieves, characterized in that, The method includes: 1) Mix the titanium silicate molecular sieve, modifier, and water to obtain a mixture; 2) The mixture obtained in step 1) is subjected to hydrothermal modification treatment to obtain the hydrothermally modified product; 3) The hydrothermal modification product obtained in step 2) is subjected to solid-liquid separation to obtain a solid phase and a liquid phase; 4) The solid phase obtained in step 3) is washed, dried and subjected to a first calcination to obtain the modified titanium-silicon molecular sieve; 5) Contact the liquid phase obtained in step 3) and / or the washing solution obtained in step 4) with the nanoporous material. The modifier is a basic organic modifier, and the basic organic modifier is selected from quaternary ammonium compounds. The specific surface area of ​​the nanoporous material is greater than that of the modified titanium-silicon molecular sieve, and the pore size of the nanoporous material is greater than that of the modified titanium-silicon molecular sieve. The nanoporous material is SBA-15 mesoporous molecular sieve and / or HY molecular sieve. In step 5), the weight ratio of the liquid phase obtained in step 3) and / or the washing liquid obtained in step 4) to the nanoporous material is 5-10:

1.

2. The modification method according to claim 1, wherein, The general formula of the quaternary ammonium alkali compound is (R 1 )4NOH, where R 1 It is an alkyl group having 1-4 carbon atoms.

3. The modification method according to claim 1, wherein, The quaternary ammonium compound is tetrapropylammonium hydroxide.

4. The modification method according to any one of claims 1-3, wherein, In step 1), the weight ratio of the titanium silicate molecular sieve, the modifier, and the water is 100:(0.1-10):(200-5000).

5. The modification method according to claim 4, wherein, In step 1), the weight ratio of the titanium silicate molecular sieve, the modifier, and the water is 100:(0.5-5):(300-1000).

6. The modification method according to any one of claims 1-3, wherein, In step 2), the conditions for the hydrothermal modification treatment include: a temperature of 120-200℃ and a time of 2-48h.

7. The modification method according to claim 6, wherein, In step 2), the conditions for the hydrothermal modification treatment include: a temperature of 140-180℃ and a time of 4-24h.

8. The modification method according to any one of claims 1-3, wherein, In step 4), the conditions for the first roasting include: a temperature of 300-700℃ and a time of 0.5-6h.

9. The modification method according to claim 8, wherein, In step 4), the conditions for the first roasting include: a temperature of 400-600℃ and a time of 1-3h.

10. The modification method according to any one of claims 1-3, wherein, In step 5), the contact conditions include: a temperature of 20-100℃ and a time of less than 5 hours.

11. The modification method according to claim 10, wherein, In step 5), the contact conditions include: a temperature of 20-80℃ and a time of 10-120 minutes.

12. The modification method according to claim 11, wherein, In step 5), the contact conditions include: a temperature of 30-60°C and a time of 20-60 minutes.

13. The modification method according to any one of claims 1-3, wherein, The specific surface area of ​​the nanoporous material is 20-200% larger than that of the modified titanium-silicon molecular sieve.

14. The modification method according to claim 13, wherein, The specific surface area of ​​the nanoporous material is 30-100% larger than that of the modified titanium-silicon molecular sieve.

15. The modification method according to any one of claims 1-3, wherein, The pore size of the nanoporous material is 20-2500% larger than that of the modified titanium-silicon molecular sieve.

16. The modification method according to claim 15, wherein, The pore size of the nanoporous material is 40-1000% larger than that of the modified titanium-silicon molecular sieve.

17. The modification method according to any one of claims 1-3, wherein, The modification method further includes a step of second calcining the nanoporous material after contact in step 5).

18. The modification method according to claim 17, wherein, The conditions for the second roasting include: a temperature of 400-700℃ and a time of 1-6 hours.

19. The modification method according to claim 18, wherein, The conditions for the second roasting include: a temperature of 500-600℃ and a time of 2-4 hours.

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