Preparation method of modified Ti-MSU molecular sieve catalyst, modified Ti-MSU molecular sieve catalyst and application

Abstract

The application discloses a preparation method of a modified Ti-MSU molecular sieve catalyst, the modified Ti-MSU molecular sieve catalyst and application. The application introduces active metal compounds and nanometer carbon fibers into the Ti-MSU catalyst, and a modified Ti-MSU molecular sieve catalyst with better waterproofness and anti-coking performance is obtained; the modified catalyst is used in a DCPD catalytic oxidation synthesis DCPDDO process, and the catalyst is not easy to be deactivated and can be operated for a long time, and the DCPD conversion rate and DCPDDO selectivity are high.

Description

Technical Field

[0001] This invention relates to the technical field of catalytic oxidation synthesis of organic epoxides and olefins, and more specifically, to a method for preparing modified Ti-MSU molecular sieve catalysts, and the modified Ti-MSU molecular sieve catalysts and their applications. Background Technology

[0002] DCPD (dicyclopentadiene) is an important component of the C9 fraction of ethylene cracking, accounting for approximately 17-28% of the C9 fraction. DCPD's epoxidation product, DCPDDO (dicyclopentadiene dioxide), is a special alicyclic epoxy resin monomer. Alicyclic epoxy resins account for about 5% of total epoxy resin consumption, and among the many alicyclic epoxy resin products, dicyclopentadiene dioxide epoxy resin is particularly noteworthy. Due to the high crosslinking density and rigidity of DCPDDO with cured anhydrides, the cured product retains high strength even at heat distortion temperatures above 300℃, exhibiting particularly excellent electrical properties at high temperatures. Therefore, dicyclopentadiene dioxide epoxy resin is suitable for use as casting insulation for outdoor instrument transformers, casting materials for micro-motor rotors, high-humidity resistant epoxy resin encapsulants, carbon fiber (or glass fiber) wound high-voltage containers, high-elasticity modulus composite materials, resin alloy molds, high-temperature resistant laminates, high-strength weather-resistant fiberglass, radiation-resistant coatings, and in the manufacture of aerospace and defense equipment, with a promising market prospect.

[0003] Currently, the main industrial production of dicyclopentadiene dioxide uses the peracetic acid process. First, glacial acetic acid reacts with H₂O₂ to produce peracetic acid. Then, peracetic acid is used as an oxidant, and 98% concentrated sulfuric acid is used as a catalyst to catalyze the oxidation of dicyclopentadiene to produce dicyclopentadiene dioxide. This process has low safety, severe equipment corrosion, large amounts of waste, and limited production scale and output, restricting its application. The only domestic producers of dicyclopentadiene dioxide are Jiangsu Taiter, Tianjin Jingdong, and Yueyang Changde, all using this process, but with low capacity and output. Other dicyclopentadiene dioxide synthesis methods under research include the alkyl hydrogen peroxide method, the sodium perborate method, the sodium perdicarbonate method, and the H₂O₂ / heteropolyacid compound method. The alkyl hydrogen peroxide method can achieve relatively ideal yields, but the reaction temperature is high, the risk factor is high, and strict requirements are placed on the water content and carbonyl byproduct content. Furthermore, the oxidant and catalyst are expensive and difficult to recycle. The sodium perborate method uses sodium perborate, a relatively safe oxidant, to carry out the epoxidation reaction at room temperature. The process is safe and the operating conditions are simple, but the reaction time is long, there are many side reactions, and the yield is low, only 50%. The sodium percarbonate method uses ultrasonic radiation to carry out the epoxidation reaction, shortening the reaction time and increasing the yield of the target product. However, this process is not economically viable, and the yield is low, leaving considerable room for industrial production. In recent years, the H₂O₂ / heteropolyacid compound method has attracted widespread attention from researchers. Based on their catalytic reaction mechanism, it can be divided into homogeneous catalysts and heterogeneous catalysts. Homogeneous catalysis involves adding heteropolyacids or other salts to the reaction system, resulting in high catalytic activity and a simple process. However, the catalyst and aqueous phase are mixed together and cannot be separated or recycled, making industrial scale-up difficult. Heterogeneous catalysis, on the other hand, maintains high catalytic efficiency while achieving catalyst recycling, but currently still suffers from problems such as easy shedding of heteropolyacids and short catalyst lifetime.

[0004] With the increasing demand for dicyclopentadiene dioxide, traditional dicyclopentadiene oxidation technology can no longer meet market demands, making it imperative to research and develop new catalysts and reaction processes. Summary of the Invention

[0005] To address the problems in existing technologies, this invention proposes a method for preparing modified Ti-MSU molecular sieve catalysts, as well as the modified Ti-MSU molecular sieve catalysts and their applications. This invention synthesizes a modified Ti-MSU molecular sieve catalyst with metal compound modification and nanofiber / Ti-MSU as the support. Applied to DCPDDO synthesis, it achieves a longer catalyst lifespan while maintaining a higher DCPDDO product yield, thus solving the problems of short catalyst lifespan and low DCPDDO yield in existing DCPDDO synthesis processes.

[0006] One objective of this invention is to provide a method for preparing a modified Ti-MSU molecular sieve catalyst, comprising the following steps:

[0007] (1) The template agent was dissolved in acidic water, and silicon source, titanium source and organic alcohol were added. The mixture was heated and stirred. Then, carbon nanofibers were added and stirred again. The mixture was crystallized. After solid-liquid separation, washing and drying, carbon nanofiber-supported Ti-MSU was obtained.

[0008] (2) The Ti-MSU supported on the nanofibers is added to an aqueous solution of a metal compound, stirred, and after solid-liquid separation, washing, and drying, it is calcined in a protective atmosphere to obtain the modified Ti-MSU molecular sieve catalyst matrix.

[0009] (3) The modified Ti-MSU molecular sieve catalyst parent material is subjected to silanization treatment with organosilicon solution under a protective atmosphere. After solid-liquid separation and drying, the modified Ti-MSU molecular sieve catalyst is obtained.

[0010] In the preparation method of the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0011] In step (1),

[0012] Dissolve the template agent in acidic water, and add dropwise a mixture of silicon source, titanium source, and organic alcohol; and / or,

[0013] The template agent is selected from polyoxyethylene ether template agents; preferably, the template agent is selected from at least one of dodecyl polyoxyethylene ether, octadecyl polyoxyethylene ether, or lauryl polyoxyethylene ether; and / or,

[0014] The acidic water has a pH of 2-3, preferably adjusted using 0.5-1 mol / L hydrochloric acid or sulfuric acid, more preferably adjusted at 50-60°C; and / or,

[0015] The silicon source is selected from tetraalkyl silicate; preferably, the silicon source is selected from at least one of tetramethyl silicate, tetraethyl silicate, or tetrabutyl silicate; and / or,

[0016] The titanium source is selected from at least one of tetraalkyl titanate and titanium chloride; preferably, the titanium source is selected from at least one of tetrabutyl titanate, titanium trichloride, or titanium tetrachloride; and / or,

[0017] The organic alcohol is selected from at least one of organic alcohols having 1-5 carbon atoms; preferably, the organic alcohol is selected from at least one of ethanol, isopropanol, or isobutanol; and / or,

[0018] The carbon nanofibers are formed by a carbon-containing gas source selected from CO, CH4, C2H6, or C3H8 as raw materials, and using any single metal element or alloy of multiple elements from Group VIII of the periodic table as a catalyst, through a catalytic cracking reaction of the carbon-containing gas source. Preferably, the temperature of the catalytic cracking reaction of the carbon-containing gas source is 600-1200℃, and the reaction time is 60-80 min; and / or, the Group VIII element is selected from any single metal element or alloy of multiple elements from Fe, Co, or Ni; and / or, the ratio of the number of metal atoms in the catalyst to the number of carbon atoms in the carbon-containing gas source is 0.0001-0.0004:1.

[0019] The carbon nanofibers prepared by the above method have an average outer diameter of 80-150 nm and an average fiber length of 13-20 μm.

[0020] In the preparation method of the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0021] In step (1),

[0022] The heating and stirring process is carried out at a temperature of 50–60°C; and / or,

[0023] The heating and stirring treatment time is 12–36 hours; and / or,

[0024] The temperature for continued stirring is 50–60°C; and / or,

[0025] The stirring time is 24–80 hours; and / or,

[0026] The crystallization treatment temperature is 130–180°C; and / or the crystallization treatment time is 24–72 h.

[0027] In the preparation method of the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0028] In step (1),

[0029] The molar ratio of template agent to silicon source is (0.1–1):1; and / or,

[0030] The molar ratio of silicon source to titanium source is 1:(0.02–0.1); and / or,

[0031] The molar ratio of silicon source to organic alcohol is 1:(10–15); and / or,

[0032] The molar ratio of silicon source to acidic water is 1:(150–200); and / or,

[0033] The molar ratio of silicon source to carbon nanofiber is 1:(5-15).

[0034] In the preparation method of the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0035] In step (2),

[0036] The metal compound is selected from at least one of MgO, MgCO3, Mg(OH)2, MoO3, or (NH4)2MoO4; and / or,

[0037] The aqueous solution of the metal compound is a saturated aqueous solution of the metal compound; preferably, the volume ratio of Ti-MSU supported on carbon nanofibers to the saturated aqueous solution of the metal compound is 1:(1-4); and / or,

[0038] The stirring time is 12–48 hours; and / or,

[0039] The stirring temperature is room temperature; and / or,

[0040] The roasting temperature is 500–700℃; and / or,

[0041] The roasting time is 4 to 10 hours.

[0042] In the preparation method of the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0043] In step (3),

[0044] The organic solvent in the organosilicon solution is selected from benzene-based solvents, preferably at least one of toluene, ethylbenzene, or cumene; and / or,

[0045] The organosilicon in the organosilicon solution is selected from at least one of trimethylchlorosilane, triethylchlorosilane, dimethylphenylchlorosilane, or hexamethyldisilazane; and / or,

[0046] The amount of organosilicon in the organosilicon solution is 20-80% of the weight of the modified Ti-MSU molecular sieve catalyst parent material; preferably, the organosilicon solution is a saturated organosilicon solution.

[0047] In the preparation method of the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0048] In step (3),

[0049] The silanization treatment temperature is 50–350 °C; and / or,

[0050] The silanization treatment time is 2–50 h; and / or,

[0051] The drying temperature is 100–200℃; and / or,

[0052] The drying time is 12 to 24 hours.

[0053] In this invention, the protective gas is a commonly used protective gas in the prior art, selected from at least one of nitrogen and inert gases.

[0054] A second objective of this invention is to provide a modified Ti-MSU molecular sieve catalyst prepared by the preparation method described in the first objective of this invention.

[0055] The catalyst of the present invention is a composite catalyst obtained by silanizing a modified Ti-MSU molecular sieve catalyst matrix; wherein, the modified Ti-MSU molecular sieve catalyst matrix includes a Ti-MSU / nanocarbon fiber composite support and a metal compound supported on Ti-MSU / nanocarbon fiber and then calcined.

[0056] In the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0057] The catalyst has a three-dimensional mesoporous structure; preferably, the specific surface area of ​​the catalyst is 725–978 m². 2 g -1 The pore size is 3.75–4.75 nm, and the pore volume is 0.78–1.18 cm³. 3 g -1 .

[0058] In the modified Ti-MSU molecular sieve catalyst described in this invention, preferably,

[0059] In the catalyst,

[0060] The molar ratio of silicon to titanium is 1:(0.02–0.1); and / or,

[0061] The molar ratio of silicon to carbon nanofiber is 1:(5-15).

[0062] The loading of the calcined metal compound in the catalyst of this invention can be measured by conventional testing methods in the art, or the loading of the calcined metal compound can be determined by the difference between the modified Ti-MSU molecular sieve catalyst matrix and the Ti-MSU supported on carbon nanofibers. Similarly, the mass change of the catalyst before and after silanization treatment can be determined by the same method.

[0063] A third objective of this invention is to provide an application of a modified Ti-MSU molecular sieve catalyst prepared by the preparation method described in one objective of this invention, or a modified Ti-MSU molecular sieve catalyst described in another objective of this invention, in the epoxidation reaction of olefins; preferably, in the epoxidation reaction of dicyclopentadiene to prepare dicyclopentadiene dioxide.

[0064] In the application described in this invention, preferably,

[0065] Dicyclopentadiene and cumene hydroperoxide undergo an epoxidation reaction in an organic solvent under the action of a catalyst.

[0066] Preferably,

[0067] The organic solvent is a benzene derivative, preferably cumene; and / or,

[0068] The molar ratio of dicyclopentadiene, cumene hydroperoxide, and the organic solvent is 1:(2-3):(6-11), preferably 1:(2.1-2.3):(8-10); and / or,

[0069] The epoxidation reaction is carried out at a temperature of 70–120 °C; and / or,

[0070] The pressure for the epoxidation reaction is 0.5–1.5 MPaG; and / or,

[0071] The total reactant feed mass hourly space velocity is 0.5–3 h⁻¹. -1 ; and / or,

[0072] More preferably,

[0073] The epoxidation reaction is carried out at a temperature of 80–110 °C; and / or,

[0074] The pressure for the epoxidation reaction is 0.8–1.0 MPaG; and / or,

[0075] The total reactant feed mass hourly space velocity is 0.5–2 h⁻¹. -1 .

[0076] The present invention has the following advantages:

[0077] (1) Compared with the peracetic acid method in the prior art, the method of olefin epoxidation of the present invention does not require the use of strong corrosive substances such as acids and alkalis, has low requirements for equipment materials, and has low equipment investment and maintenance costs.

[0078] (2) The modified Ti-MSU molecular sieve catalyst provided by the present invention is modified with metal compounds and carbon nanofibers, which makes it more hydrophobic and resistant to coking. It not only has high DCPD conversion and DCPDDO selectivity, but also has a longer catalyst life and can operate for a long period of time.

[0079] (3) The method of the present invention is not only applicable to the oxidation of dicyclopentadiene to prepare dicyclopentadiene dioxide, but can also be widely applied to various olefin epoxidation reactions, and has good industrial application prospects.

[0080] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; 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. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein. Detailed Implementation

[0081] The present invention will now be described in detail with reference to specific examples and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0082] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0083] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0084] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0085] The carbon fiber used in this embodiment of the invention: The carbon nanofiber is formed by using a carbon-containing gas source CH4 as raw material and selecting Co, an element of Group VIII of the periodic table, as a catalyst. The ratio of the number of metal atoms in the catalyst to the number of carbon atoms in the carbon-containing gas source is 0.0002:1. The carbon nanofiber is formed by a carbon-containing gas source catalytic cracking reaction. Preferably, the temperature of the carbon-containing gas source catalytic cracking reaction is 1000℃ and the reaction time is 70min.

[0086] Example 1

[0087] (1) Under room temperature and stirring conditions, 20.5 g of dodecyl polyoxyethylene ether (molecular weight 582.81) was first dissolved in 540 g of acidic water with pH value 2. Then, a mixture of 30.4 g tetramethyl silicate, 1.4 g tetrabutyl titanate and 92 g ethanol was added dropwise to the above solution. The mixture was heated to 50 °C and stirred for 12 h. The mixture was poured into a 1000 mL reactor, 12 g of carbon nanofibers were added, and the mixture was stirred for 24 h. The mixture was heated to 130 °C and crystallized for 24 h. The solid was filtered, washed with pure water until neutral, and dried at 80 °C for 12 h to obtain carbon nanofiber-supported Ti-MSU.

[0088] (2) The obtained carbon nanofiber supported Ti-MSU was added to a 1-volume saturated aqueous solution of MgO, stirred at room temperature for 12 h, filtered out the solid, washed with pure water until neutral, dried at 80 °C for 12 h, and calcined at 500 °C for 4 h under helium protection to obtain a Ti-MSU catalyst matrix modified with metal compound and supported by carbon nanofiber.

[0089] (3) In a 100 mL reactor, 20 g of the prepared Ti-MSU catalyst precursor was added, along with 30 mL of a toluene solution containing 4 g of trimethylchlorosilane. Under nitrogen protection, the mixture was stirred at 50 °C for 2 h, and the reaction was terminated. After the material cooled naturally, the solid catalyst was filtered out and dried at 100 °C for 12 h to obtain a silanized Ti-MSU / nanocarbon fiber composite catalyst modified with metal compounds.

[0090] Example 2

[0091] (1) Under room temperature and stirring conditions, 109.6 g of octadecyl polyoxyethylene ether (molecular weight of about 770) was first dissolved in 648 g of acidic water with a pH of 3. Then, a mixture of 41.7 g tetraethyl silicate, 1.6 g titanium trichloride and 144 g isopropanol was added dropwise to the above solution. The mixture was heated to 55 °C and stirred for 24 h. The mixture was poured into a 1000 mL reactor, 19.2 g of carbon nanofibers were added, and the mixture was stirred for another 48 h. The mixture was heated to 150 °C and crystallized for 48 h. The solid was filtered, washed with pure water until neutral, and dried at 80 °C for 12 h to obtain carbon nanofiber-supported Ti-MSU.

[0092] (2) The obtained carbon nanofiber supported Ti-MSU was added to 2 times the volume of MgCO3 saturated aqueous solution, stirred at room temperature for 24 h, filtered out the solid, washed with pure water until neutral, dried at 80 °C for 12 h, and calcined at 600 °C for 6 h under helium protection to obtain a Ti-MSU catalyst matrix modified with metal compound and supported by carbon nanofiber.

[0093] (3) 20g of the prepared Ti-MSU catalyst matrix was added to a 100mL reactor, along with 50mL of ethylbenzene solution containing 4g of triethylchlorosilane. The reaction was carried out under nitrogen protection at 150℃ with stirring for 20h, and then the reaction was terminated. After the material cooled naturally, the solid catalyst was filtered out and dried at 150℃ for 16h to obtain a silanized Ti-MSU / nanocarbon fiber composite catalyst modified with metal compounds.

[0094] Example 3

[0095] (1) Under room temperature and stirring conditions, 72g of lauryl alcohol polyoxyethylene ether (molecular weight 1316) was first dissolved in 576g of acidic water with pH value 2. Then, a mixture of 64.1g of tetrabutyl orthosilicate, 3.0g of titanium tetrachloride and 207.48g of isobutanol was added dropwise to the above solution. The mixture was heated to 60℃ and stirred for 36h. The mixture was poured into a 1000mL reactor, 24g of carbon nanofibers were added, and the mixture was stirred for 72h. The mixture was heated to 160℃ and crystallized for 60h. The solid was filtered, washed with pure water until neutral, and dried at 80℃ for 12h to obtain Ti-MSU supported on carbon nanofibers.

[0096] (2) The obtained carbon nanofiber supported Ti-MSU was added to 3 times the volume of MoO3 saturated aqueous solution, stirred at room temperature for 36 h, filtered out the solid, washed with pure water until neutral, dried at 80 °C for 12 h, and calcined at 650 °C for 8 h under helium protection to obtain a Ti-MSU catalyst matrix with metal compound modification and carbon nanofiber as support.

[0097] (3) In a 100 mL reactor, 20 g of the prepared Ti-MSU catalyst precursor was added, along with 50 mL of cumene solution containing 4 g of dimethylphenylchlorosilane. Under nitrogen protection, the mixture was stirred at 300 °C for 36 h, and the reaction was terminated. After the material cooled naturally, the solid catalyst was filtered out and dried at 170 °C for 20 h to obtain a silanized Ti-MSU / nanocarbon fiber composite catalyst modified with metal compounds.

[0098] Example 4

[0099] (1) Under room temperature and stirring conditions, 219.2 g of octadecyl polyoxyethylene ether (molecular weight of about 770) was first dissolved in 720 g of acidic water with a pH of 3. Then, a mixture of 41.66 g of tetraethyl silicate, 6.8 g of tetrabutyl titanate and 138 g of ethanol was added dropwise to the above solution. The mixture was heated to 60 °C and stirred for 24 h. The mixture was poured into a 1000 mL reactor, 36 g of carbon nanofibers were added, and the mixture was stirred for another 80 h. The mixture was heated to 180 °C and crystallized for 72 h. The solid was filtered, washed with pure water until neutral, and dried at 80 °C for 12 h to obtain carbon nanofiber-supported Ti-MSU.

[0100] (2) The obtained carbon nanofiber supported Ti-MSU was added to 4 times the volume of (NH4)2MoO4 saturated aqueous solution, stirred at room temperature for 48 h, filtered out the solid, washed with pure water until neutral, dried at 80 °C for 12 h, and calcined at 700 °C for 10 h under helium protection to obtain a Ti-MSU catalyst matrix modified with metal compound and supported by carbon nanofiber.

[0101] (3) 20g of the prepared Ti-MSU catalyst matrix was added to a 100mL reactor, along with 60mL of ethylbenzene solution containing 4g of hexamethyldisilazane. The reaction was carried out under nitrogen protection at 350℃ for 50h with stirring, and then the reaction was terminated. After the material cooled naturally, the solid catalyst was filtered out and dried at 200℃ for 24h to obtain a silanized Ti-MSU / nanocarbon fiber composite catalyst modified with metal compounds.

[0102] The above embodiments of the present invention provide a metal compound modified Ti-MSU / nanocarbon fiber composite catalyst, wherein the Ti-MSU catalyst has three-dimensional mesoporous characteristics (specific surface area 725-978 m²). 2 g -1 The pore size is 3.75–4.75 nm, and the pore volume is 0.78–1.18 cm³. 3 g -1 Ti-MSU / nanocarbon fiber composite catalyst with metal oxide modification treatment.

[0103] Comparative Example 1

[0104] It uses essentially the same preparation method as Example 4, the only difference being that...

[0105] In step (1), the step of loading carbon nanofibers is not performed.

[0106] Comparative Example 2

[0107] It uses essentially the same preparation method as Example 4, the only difference being that...

[0108] The metal compound modification treatment in step (2) is not performed.

[0109] Comparative Example 3

[0110] It uses essentially the same preparation method as Example 4, the only difference being that...

[0111] The silanization process in step (3) is not performed.

[0112] Examples 5-20

[0113] The catalysts prepared in Examples 1-4 and Comparative Examples 1-3 were used to synthesize dicyclopentadiene dioxide in a 100 mL fixed-bed reactor. The effects of temperature, pressure, material ratio, and feed space velocity on the product were investigated in a continuous reaction process. The results are shown in Table 1.

[0114] The catalysts used in Examples 5-8 were provided by Example 1, the catalysts used in Examples 9-12 were provided by Example 2, the catalysts used in Examples 13-16 were provided by Example 3, and the catalysts used in Examples 17-20 were provided by Example 4; the catalysts used in Examples 21-23 were provided by Comparative Examples 1, 2, and 3, respectively.

[0115] Table 1

[0116]

[0117] Example 24

[0118] Using the modified Ti-MSU prepared in Example 4 as a catalyst, the reaction was carried out at a reaction temperature of 100°C, a reaction pressure of 1.0 MPaG, and a feed space velocity of 1.0 h⁻¹. -1 Under the given conditions, DCPD, CHP, and cumene were introduced into a 100 mL fixed-bed reactor in a molar ratio of 1:2.2:10 to undergo a continuous epoxidation reaction. The effect of catalyst lifetime on the reaction was investigated, and the results are shown in Table 2.

[0119] Table 2

[0120] Catalyst lifetime DCPD conversion rate DCPDDO Selective h ％ ％ 24 100 100 240 99.9 100 480 99.8 99.9 720 99.8 99.8

[0121] Comparative Example 4

[0122] Commercially available Ti-MSU-1 molecular sieve was used as a catalyst as a comparative example. The experimental method was the same as in Example 24 to investigate the effect of catalyst lifetime on the reaction. The results are shown in Table 3.

[0123] Table 3

[0124] Catalyst lifetime DCPD conversion rate DCPDDO Selective h ％ ％ 24 95.2 98.0 240 93.1 96.5 480 90.5 95.6 720 85.3 91.7

[0125] Existing Ti-MSU molecular sieve catalysts used in the synthesis of DCPDDO exhibit good initial activity, but their catalytic activity decreases with increasing lifespan. This is attributed to the decomposition of CHP (cumene hydroperoxide) during the reaction, which produces water and acid. This decomposition can lead to polymerization of the reaction products, causing pore blockage, framework breakage, and titanium loss, ultimately affecting the catalyst's catalytic performance.

[0126] This invention synthesizes a Ti-MSU catalyst modified with metal compounds and supported by carbon nanofibers, which is applied to the synthesis of DCPDDO. While maintaining a higher DCPDDO product yield, it also achieves a longer catalyst lifespan.

[0127] Comparative Example 5

[0128] Using the catalysts in Comparative Examples 1-3 as comparative examples, the experimental method was the same as in Example 24 to investigate the effect of catalyst lifetime on the reaction. The results are shown in Table 4.

[0129] Table 4

[0130] catalyst Catalyst lifetime DCPD conversion rate DCPDDO Selective h ％ ％ Comparative Example 1 480 92.2 96.1 Comparative Example 2 480 91.7 96.8 Comparative Example 3 480 93.1 95.4

[0131] The results above show that, according to the catalyst preparation method provided by this invention, using carbon nanofibers as a support and modifying with metal compounds, the catalyst's water resistance is greatly increased and its service life is longer.

[0132] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0133] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0134] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0135] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

Claims

1. A method for preparing a modified Ti-MSU molecular sieve catalyst, characterized in that, It comprises the following steps: (1) Dissolve the template agent in acidic water, add the silicon source, titanium source and organic alcohol, and then perform heating and stirring treatment. Then add the nanometer carbon fiber and continue stirring, and then perform crystallization treatment. After solid-liquid separation, washing and drying, the nanometer carbon fiber loaded Ti-MSU is obtained. The nanometer carbon fiber is formed by carbon-containing gas source catalytic cracking reaction. The temperature of the carbon-containing gas source catalytic cracking reaction is 1000-1200°C, and the reaction time is 60-80 min; (2) Add the nanometer carbon fiber loaded Ti-MSU to an aqueous solution of a metal compound, stir, and then perform solid-liquid separation, washing and drying. Then, calcine in a protective atmosphere to obtain a modified Ti-MSU molecular sieve catalyst precursor. The metal compound is selected from at least one of MoO3 or (NH4)2MoO4; (3) Perform silanization treatment on the modified Ti-MSU molecular sieve catalyst precursor in a protective atmosphere using an organic silicon solution. After solid-liquid separation and drying, the modified Ti-MSU molecular sieve catalyst is obtained.

2. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: In step (1), the template agent is selected from polyoxyethylene ether template agents; and / or, the pH value of the acidic water is 2-3; and / or, the silicon source is selected from tetraalkyl silicate; and / or, the titanium source is selected from at least one of tetraalkyl titanate and titanium chloride; and / or, the organic alcohol is selected from at least one of organic alcohols with 1-5 carbon atoms; and / or, the nanometer carbon fiber is formed by carbon-containing gas source catalytic cracking reaction using at least one of CO, CH4, C2H6 or C3H8 as the raw material and any one single metal element or multi-element alloy of the elements in Group VIII of the periodic table as the catalyst.

3. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 2, characterized in that: In step (1), the template agent is selected from at least one of dodecyl polyoxyethylene ether, octadecyl polyoxyethylene ether or lauryl polyoxyethylene ether; and / or, the pH value of the acidic water is 2-3, and the pH value of the water is adjusted by 0.5-1 mol / L hydrochloric acid or sulfuric acid; and / or, the silicon source is selected from at least one of tetramethyl silicate, tetraethyl silicate or n-butyl silicate; and / or, the titanium source is selected from at least one of tetrabutyl titanate, titanium trichloride or titanium tetrachloride; and / or, the organic alcohol is selected from at least one of ethanol, isopropyl alcohol or isobutyl alcohol; and / or, the element in Group VIII is any one single metal element or multi-element alloy of Fe, Co or Ni; and / or, the ratio of the number of atoms of the metal element in the catalyst to the number of carbon atoms in the carbon-containing gas source is (0.0001-0.0004):

1.

4. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 3, characterized in that: The pH value of the water is adjusted at 50-60°C.

5. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: The temperature of the heating and stirring treatment in step (1) is 50-60℃; and / or, The time of the heating and stirring treatment is 12-36h; and / or, The temperature of the continuing stirring is 50-60℃; and / or, The time of the continuing stirring is 24-80h; and / or, The temperature of the crystallization treatment is 130-180℃; and / or, the time of the crystallization treatment is 24-72h.

6. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: The molar ratio of the template agent to the silicon source in step (1) is (0.1-1):1; and / or, The molar ratio of the silicon source to the titanium source is 1:(0.02-0.1); and / or, The molar ratio of the silicon source to the organic alcohol is 1:(10-15); and / or, The molar ratio of the silicon source to the acidic water is 1:(150-200); and / or, The molar ratio of the silicon source to the nanometer carbon fiber is 1:(5-15).

7. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: The aqueous solution of the metal compound in step (2) is a saturated aqueous solution of the metal compound; and / or, The time of the stirring is 12-48h; and / or, The temperature of the stirring is room temperature; and / or, The temperature of the calcination is 500-700℃; and / or, The time of the calcination is 4-10h.

8. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 7, characterized in that: The volume ratio of the nanometer carbon fiber loaded Ti-MSU to the saturated aqueous solution of the metal compound is 1:(1-4).

9. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: The organic solvent in the organic silicon solution in step (3) is selected from benzene solvents; and / or, The organic silicon in the organic silicon solution is selected from at least one of trimethylchlorosilane, triethylchlorosilane, dimethylphenylchlorosilane or hexamethyldisilazane; and / or, The amount of the organic silicon in the organic silicon solution is 20-80% of the weight of the modified Ti-MSU molecular sieve catalyst precursor.

10. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: The organic solvent in the organic silicon solution is selected from at least one of toluene, ethylbenzene or cumene; and / or, The organic silicon solution is a saturated organic silicon solution.

11. The preparation method of the modified Ti-MSU molecular sieve catalyst according to claim 1, characterized in that: The temperature of the silylation treatment in step (3) is 50-350℃; and / or, The time of the silylation treatment is 2-50h; and / or, The temperature of the drying treatment is 100-200℃; and / or, The time of the drying treatment is 12-24h.

12. A modified Ti-MSU molecular sieve catalyst prepared by the preparation method of any one of claims 1-11. ​ ​ ​ ​ ​ 13. The use of the modified Ti-MSU molecular sieve catalyst prepared by the preparation method of any one of claims 1-11 or the modified Ti-MSU molecular sieve catalyst of claim 12 in an olefin epoxidation reaction.

14. The use of claim 13, wherein the use is in the preparation of dicyclopentadiene dioxide by the epoxidation of dicyclopentadiene.

15. The use of claim 14, wherein the epoxidation of dicyclopentadiene is carried out in the presence of a catalyst.

16. The use of claim 15, wherein the organic solvent is a benzene; and / or the molar ratio of dicyclopentadiene, cumene hydroperoxide and the organic solvent is 1:(2-3):(6-11); and / or the epoxidation is carried out at a temperature of 70-120°C; and / or the epoxidation is carried out at a pressure of 0.5-1.5 MPaG; and / or 17. The use of claim 16, wherein the organic solvent is cumene; and / or the molar ratio of dicyclopentadiene, cumene hydroperoxide and the organic solvent is 1:(2.1-2.3):(8-10); and / or the epoxidation is carried out at a temperature of 80-110°C; and / or the epoxidation is carried out at a pressure of 0.8-1.0 MPaG; and / or ​ ​ ​ ​ ​ The total reaction mass feed mass space velocity is 0.5-3 h -1 . ​ ​ ​ ​ ​ The total reaction mass feed mass space velocity is 0.5-2 h -1 .

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