Zinc-modified composite molecular sieve catalyst, and preparation method and application thereof

Abstract

This invention provides a zinc-modified composite molecular sieve catalyst, its preparation method, and its application, relating to the field of molecular sieve catalysts. The zinc-modified composite molecular sieve catalyst comprises zinc and a composite molecular sieve, wherein the composite molecular sieve is an MCM-22 / MCM-41 composite molecular sieve, and the zinc content is 1%-10% by weight of the total weight of the zinc-modified composite molecular sieve catalyst. The catalyst provided by this invention features an MCM-22 / MCM-41 composite molecular sieve with a microporous-mesoporous composite structure, exhibiting good thermal stability and resistance to decomposition during the preparation of diisopropylnaphthalene, and possessing high overall acid strength. Zinc modification adjusts the ratio and intensity distribution of Brønsted (B) and Lewis (L) acids in the MCM-22 / MCM-41 composite molecular sieve, optimizing the synthesis process, enhancing the alkylation performance of the catalyst, and improving the conversion rate of raw materials and the selectivity of diisopropylnaphthalene.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve catalysts, specifically to zinc-modified composite molecular sieve catalysts, their preparation methods, and applications. Background Technology

[0002] Diisopropylnaphthalene is a widely used compound. Isopropylnaphthalene series heat transfer oils are popular due to their advantages such as being odorless, non-corrosive to metals, having good thermal stability, excellent low-temperature performance, and being recyclable. The main products in the isopropylnaphthalene series include monoisopropylnaphthalene, diisopropylnaphthalene, and triisopropylnaphthalene. For example, diisopropylnaphthalene (DIPN) is an important organic chemical raw material and a raw material for high-performance engineering plastics. Because of its many advantages, including being colorless, odorless, having a high boiling point, low toxicity, low pour point, and strong fuel solubility, diisopropylnaphthalene is widely used as a solvent in the printing, coatings and paints, and adhesives industries. It can also be used as a plant growth regulator in agricultural production. Furthermore, it is a high-performance high-temperature synthetic heat transfer oil and electrical insulating oil.

[0003] The production method of diisopropylnaphthalene is usually based on the liquid-phase alkylation of naphthalene and propylene. Patent CN103664494A provides a method for the liquid-phase alkylation of naphthalene and propylene. By using a naphthalene alkylation method, naphthalene and propylene are used as raw materials, a zeolite with an organosilicon skeleton structure is used as a catalyst, the reaction temperature is 130-350℃, the reaction pressure is 0-3.5 MPa, the molar ratio of naphthalene to propylene is 0.2-5:1, the weight hourly space velocity is 0.1-10 h⁻¹, the naphthalene conversion rate is 85.66%, and the selectivity of diisopropylnaphthalene is 43.81%.

[0004] He Guangxiang et al. used a self-made HM / ZrO2 catalyst to catalyze the isopropylation reaction of naphthalene at a reaction temperature of 275℃, a reaction pressure of 1.0 MPa, a n(propylene):n(naphthalene) ratio of 2:1, and a WHSV of 1 h. -1 (Based on liquid phase mass), reaction time 2 h. Under these conditions, the conversion rate of naphthalene was 85.07%, the selectivity of diisopropylnaphthalene was 45.25%, and the selectivity and yield of the target product 2,6-diisopropylnaphthalene were 17.36% and 14.77%, respectively. Qiang Min et al. used SO4... 2- The synthesis of isopropylnaphthalene via solid-state superacid catalysis using TiO2 was carried out under the following conditions: catalyst dosage of 10%, reaction temperature of 160℃, and reaction time of 2.5 h, with SO4 used twice consecutively. 2-TiO2 solid superacid catalysis was used for the alkylation of naphthalene with propylene, and the total content of monoisopropylnaphthalene, diisopropylnaphthalene, and triisopropylnaphthalene in the product was greater than 98%. Yang Changzhe et al. investigated the activity of SAPO-5 molecular sieve in the alkylation of naphthalene and propylene, and found that when the feed ratio (naphthalene to propylene molar ratio) was 1:2, the reaction temperature was 270℃, the catalyst dosage was 6%, and the reaction time was 4h, the conversion rate of naphthalene was 95.46%, and the yield and selectivity of 2,6-DIPN were 40.06% and 41.06%, respectively.

[0005] In conclusion, developing highly active and stable heterogeneous catalysts for the alkylation reaction of naphthalene and propylene to prepare diisopropylnaphthalene has significant application value. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a zinc-modified composite molecular sieve catalyst, its preparation method and application, to solve at least one of the following existing technical problems: improving the conversion rate of raw materials and improving the selectivity of diisopropylnaphthalene.

[0007] The objective of this invention is mainly achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a zinc-modified composite molecular sieve catalyst, the catalyst comprising zinc and a composite molecular sieve, wherein the composite molecular sieve is an MCM-22 / MCM-41 composite molecular sieve, and the zinc content by weight is 1%-10% based on the total weight of the zinc-modified composite molecular sieve catalyst.

[0009] Preferably, in the MCM-22 / MCM-41 composite molecular sieve, the mass ratio of MCM-22 to MCM-41 is (2:1) to (5:1).

[0010] Preferably, the silicon-to-aluminum ratio of the MCM-22 / MCM-41 composite molecular sieve is 10 to 130.

[0011] Secondly, the present invention provides a method for preparing the catalyst, comprising the following steps:

[0012] Step 1: Preparation of composite molecular sieves;

[0013] Step 2: Obtain a mixture including the composite molecular sieve and the aqueous solution of the zinc precursor to obtain the zinc-modified composite molecular sieve catalyst.

[0014] Preferably, step 1 includes the following steps:

[0015] Step 1a: Obtain a mixture including aluminum source and water, to obtain mixture A;

[0016] Step 1b: Obtain a mixture including sodium hydroxide, silicon source, template agent, and water to obtain mixture B;

[0017] Step 1c: Add mixture A to mixture B, age, and then perform a first crystallization treatment and a second crystallization treatment to obtain MCM-22 / MCM-41 composite molecular sieve.

[0018] Preferably, in step 1, the silicon source, aluminum source and water are mixed in a molar ratio of n(SiO2):n(Al2O3):n(H2O)=(20-260):1:(630-900).

[0019] Preferably, the molar ratio of template agent to aluminum source is (0.3-0.8):1, more preferably (0.4-0.7):1, and even more preferably (0.5-0.6):1.

[0020] Preferably, the molar ratio of sodium hydroxide to aluminum source is (2-6):1, more preferably (3-5):1.

[0021] Preferably, in step 1c, the temperature of the first crystallization treatment is 130℃-150℃.

[0022] Preferably, in step 1c, the first crystallization treatment takes 5-8 days.

[0023] Preferably, in step 1c, the pH of the second crystallization treatment is 9-11.

[0024] Preferably, in step 1c, the temperature of the second crystallization treatment is 100–120°C.

[0025] Preferably, in step 1c, the second crystallization treatment takes 3-10 days.

[0026] Preferably, the silicon source includes at least one of silicic acid, water glass, and silica sol; the aluminum source includes at least one of sodium aluminate, sodium metaaluminate, and aluminum nitrate; the template agent includes at least one of hexamethyleneimine, tetraethylammonium hydroxide, and tetrabutylammonium bromide; and the zinc-containing precursor includes at least one of zinc nitrate and zinc chloride.

[0027] Thirdly, the present invention provides the application of the catalyst described herein or the catalyst prepared by the method described herein in the preparation method of diisopropylnaphthalene.

[0028] Fourthly, the present invention provides a method for preparing diisopropylnaphthalene, comprising the steps of: obtaining a mixture comprising naphthalene and propylene, adding the catalyst or the catalyst prepared by the preparation method, and reacting to obtain diisopropylnaphthalene.

[0029] Preferably, in the preparation method of diisopropylnaphthalene, the amount of zinc-modified composite molecular sieve catalyst added is 0.5% to 10% of the total mass of naphthalene and propylene; the reaction temperature is 90 to 240°C; the reaction pressure is 0.5 to 2 MPa; and the molar ratio of naphthalene to propylene is 1:(2-2.2).

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] A) The catalyst provided by this invention utilizes the MCM-22 / MCM-41 composite molecular sieve, a microporous-mesoporous composite structure with good thermal stability, making it less prone to decomposition during the preparation of diisopropylnaphthalene, and exhibiting high overall acid strength. Zinc modification adjusts the ratio and intensity distribution of Brønsted (B) and Lewis (L) acids in the MCM-22 / MCM-41 composite molecular sieve, optimizing the synthesis process, enhancing the alkylation performance of the catalyst, and improving the conversion rate of raw materials and the selectivity of diisopropylnaphthalene. The catalyst provided by this invention is pollution-free, easily separable, reusable, and operates under relatively mild reaction conditions, exhibiting high safety.

[0032] B) The method for preparing diisopropylnaphthalene provided by the present invention uses propylene and naphthalene as raw materials and employs a zinc-modified composite molecular sieve catalyst to catalyze the alkylation reaction to prepare diisopropylnaphthalene. This method overcomes the shortcomings of traditional industrial methods that use strong liquid acids as catalysts, which are highly corrosive, require large quantities, and pollute the environment. It achieves clean and green production of diisopropylnaphthalene. Detailed Implementation

[0033] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0034] In a first aspect, the present invention provides a zinc-modified composite molecular sieve catalyst, comprising zinc and a composite molecular sieve, wherein the composite molecular sieve is an MCM-22 / MCM-41 composite molecular sieve, and the zinc content by weight of the zinc-modified composite molecular sieve catalyst is 1%-10%, for example 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc.

[0035] As a specific embodiment of the present invention, the mass ratio of MCM-22 to MCM-41 in the MCM-22 / MCM-41 composite molecular sieve is in the range of (2:1) to (5:1), for example, 2.5, 3, 3.5, 4, 4.5, etc.

[0036] As a specific embodiment of the present invention, the silicon-aluminum ratio of the MCM-22 / MCM-41 composite molecular sieve is 10 to 130.

[0037] The catalyst provided by this invention utilizes the MCM-22 / MCM-41 composite molecular sieve, a microporous-mesoporous composite structure with good thermal stability, making it less prone to decomposition during the preparation of diisopropylnaphthalene, and exhibiting high overall acid strength. Zinc modification adjusts the ratio and intensity distribution of Brønsted (B) and Lewis (L) acids in the MCM-22 / MCM-41 composite molecular sieve, enhancing the alkylation performance of the catalyst, optimizing the synthesis process of diisopropylnaphthalene, and improving the conversion rate and selectivity of the raw materials.

[0038] Secondly, the present invention provides a method for preparing a zinc-modified composite molecular sieve catalyst, specifically comprising the following steps:

[0039] Step 1: Preparation of microporous-mesoporous MCM-22 / MCM-41 composite molecular sieve;

[0040] Step 2: Obtain a mixture of MCM-22 / MCM-41 composite molecular sieve and zinc-containing precursor aqueous solution, perform impregnation treatment, dry and calcinate to obtain zinc-modified composite molecular sieve catalyst.

[0041] As a specific embodiment of the present invention, step 1 includes the following steps:

[0042] Step 1a: Obtain a mixture including aluminum source and water, to obtain mixture A;

[0043] Step 1b: Obtain a mixture including sodium hydroxide, silicon source, template agent, and water to obtain mixture B;

[0044] Step 1c: Add mixture A to mixture B, age, and then perform the first crystallization treatment and the second crystallization treatment;

[0045] Step 1d: Drying and calcining to obtain MCM-22 / MCM-41 composite molecular sieve.

[0046] In a specific embodiment of the present invention, in step 1, the silicon source, aluminum source and water are mixed in a molar ratio of n(SiO2):n(Al2O3):n(H2O)=(20-260):1:(630-900).

[0047] In one specific embodiment of the present invention, in step 1, the molar ratio of the template agent to the aluminum source is (0.3-0.8):1, preferably (0.4-0.7):1, and more preferably (0.5-0.6):1.

[0048] In one specific embodiment of the present invention, in step 1, the molar ratio of sodium hydroxide to aluminum source is (2-6):1, preferably (3-5):1.

[0049] In one specific embodiment of the present invention, in step 1a, the aluminum source is selected from at least one of sodium aluminate, sodium metaaluminate, and aluminum nitrate.

[0050] In one specific embodiment of the present invention, in step 1b, the silicon source is selected from at least one of silicic acid, water glass, and silica sol.

[0051] In one specific embodiment of the present invention, in step 1b, the template agent is selected from at least one of hexamethyleneimine, tetraethylammonium hydroxide, and tetrabutylammonium bromide.

[0052] In one specific embodiment of the present invention, in step 1c, the aging temperature is 50-60°C and the aging time is 6-10 hours.

[0053] In one specific embodiment of the present invention, in step 1c, the temperature of the first crystallization treatment is 130℃-150℃, and the time of the first crystallization treatment is 5-8 days.

[0054] In one specific embodiment of the present invention, in step 1c, the pH of the second crystallization treatment is 9-11, the temperature of the second crystallization treatment is 100-120°C, and the time of the second crystallization treatment is 3-10 days.

[0055] In one specific embodiment of the present invention, in step 2, the zinc-containing precursor is selected from at least one of zinc nitrate and zinc chloride.

[0056] As a specific embodiment of the present invention, step 1 may include the following steps:

[0057] Step 1-1: Mix sodium aluminate and water, and dissolve to obtain solution A;

[0058] Steps 1-2: Add silicic acid and hexamethyleneimine sequentially to the sodium hydroxide solution, and stir to obtain solution B;

[0059] Steps 1-3: Add solution A dropwise to solution B, stir thoroughly for 1 hour under nitrogen protection, and age at 60℃ for 10 hours; after aging, transfer to a crystallization reactor for the first crystallization treatment, crystallizing at 130℃-150℃ for 5-8 days; after the first crystallization treatment, quench the reactor, adjust the pH value to 9-11, and then put it back into the crystallization reactor for the second crystallization treatment, crystallizing at 100-120℃ for 3-10 days.

[0060] Steps 1-4: After the second crystallization treatment, the reactor is quenched, the pH value is adjusted to 7 again, and then dried at 130℃ for 3 hours. After calcination at 500℃ in a muffle furnace for 6 hours, the MCM-22 / MCM-41 composite molecular sieve is obtained.

[0061] As a specific embodiment of the present invention, step 2 can be as follows: using the equal volume impregnation method, the MCM-22 / MCM-41 composite molecular sieve is mixed with zinc nitrate aqueous solution, and stirred at low speed with a mechanical stirrer at room temperature until a paste is formed. After standing for 24 hours, it is dried at 100°C for 12 hours in a forced-air drying oven, and then placed in a muffle furnace and calcined at 500°C for 6 hours to obtain zinc-modified MCM-22 / MCM-41 composite molecular sieve.

[0062] Thirdly, the present invention provides an application of the above-mentioned zinc-modified composite molecular sieve catalyst in the preparation method of diisopropylnaphthalene.

[0063] Fourthly, the present invention provides a method for preparing diisopropylnaphthalene, comprising the steps of: obtaining a mixture of naphthalene and propylene, adding a zinc-modified composite molecular sieve catalyst, and reacting to obtain diisopropylnaphthalene.

[0064] The method for preparing diisopropylnaphthalene provided by this invention uses a zinc-modified MCM-22 / MCM-41 composite molecular sieve catalyst to catalyze the alkylation reaction of propylene and naphthalene to prepare diisopropylnaphthalene. It has high conversion rate and selectivity, can be recycled, and can prepare diisopropylnaphthalene type lubricating oil base oils of two viscosities. Moreover, the separation process is simple to operate and has industrial application value.

[0065] In one specific embodiment of the present invention, in the preparation method of diisopropylnaphthalene, the amount of zinc-modified composite molecular sieve catalyst added is 0.5 to 10% of the total mass of naphthalene and propylene.

[0066] In one specific embodiment of the present invention, the reaction temperature in the preparation method of diisopropylnaphthalene is 90–240°C. In this invention, this temperature range is more advantageous for improving the reaction conversion rate and selectivity in the reaction between naphthalene and propylene.

[0067] In one specific embodiment of the present invention, the reaction pressure in the preparation method of diisopropylnaphthalene is 0.5 to 2 MPa.

[0068] In one specific embodiment of the present invention, the reaction time in the method for preparing diisopropylnaphthalene is 0.5 h to 6 h. In this invention, this time range is advantageous for further improving the conversion rate and selectivity of the reaction between naphthalene and propylene.

[0069] In one specific embodiment of the present invention, the molar ratio of naphthalene to propylene is 1:(2-2.2).

[0070] As a specific embodiment of the present invention, the specific steps of the preparation method of diisopropylnaphthalene include:

[0071] Step 1: In the presence of a zinc-modified MCM-22 / MCM-41 composite molecular sieve catalyst, naphthalene and propylene are subjected to an alkylation reaction to obtain crude diisopropylnaphthalene.

[0072] Step 2: The obtained crude diisopropylnaphthalene product is vacuum filtered to remove the solid catalyst, and then the unreacted propylene and naphthalene are removed by vacuum distillation. The naphthalene source is in a molten state.

[0073] Step 3: The crude alkylnaphthalene lubricating oil base oil is subjected to vacuum distillation at 130-190℃, and the fraction obtained is diisopropylnaphthalene product.

[0074] The method for preparing diisopropylnaphthalene provided by this invention has the following advantages:

[0075] (1) The preparation method of diisopropylnaphthalene provided by the present invention uses a zinc-modified MCM-22 / MCM-41 composite molecular sieve catalyst, which has higher catalytic activity, higher reaction conversion rate and product selectivity, and the catalyst is pollution-free, easy to separate and reusable. The reaction conditions are mild and have high safety.

[0076] (2) The preparation method of diisopropylnaphthalene provided by the present invention does not require the use of organic solvents such as cyclohexane and n-heptane. After the reaction, the unreacted raw materials can be removed to directly obtain the high viscosity component of diisopropylnaphthalene type lubricating oil base oil. The separation process is simple and efficient.

[0077] (3) The preparation method of diisopropylnaphthalene provided by the present invention uses propylene and naphthalene as raw materials and zinc-modified composite molecular sieve catalyst to catalyze the alkylation reaction to prepare diisopropylnaphthalene. It develops new production processes and technologies, overcomes the shortcomings of traditional industry using liquid strong acid as catalyst, such as strong corrosiveness, large amount, and environmental pollution, and realizes the clean and green production of diisopropylnaphthalene.

[0078] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0079] Propylene was produced by the Maoming branch of China Petrochemical Corporation.

[0080] Naphthalene was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., analytical grade, CAS No.: 13446-18-9;

[0081] Zinc nitrate hexahydrate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., analytical grade, CAS number 10196-18-6;

[0082] Conversion rate and selectivity were determined by gas chromatography using a Zhejiang Fuli A90 instrument with an FID detector, nitrogen as the carrier gas, an injection volume of 2 μL, a split ratio of 50:1, and an inlet temperature of 280℃. Different temperature programs were used depending on the raw materials.

[0083] The formula for calculating the conversion rate of naphthalene is: Naphthalene conversion rate = (number of moles of naphthalene participating in the reaction / number of moles of naphthalene fed into the reactor) × 100%.

[0084] The formula for calculating the selectivity of diisopropylnaphthalene is: Selectivity = (moles of target product / moles of total reaction product) × 100%.

[0085] Preparation Example

[0086] The preparation method of the catalyst includes the following steps:

[0087] Step 1: The preparation process of MCM-22 / MCM-41 composite molecular sieve M-1 is as follows:

[0088] Step 1a: Add sodium aluminate to deionized water to dissolve it and obtain solution A;

[0089] Step 1b: Add silicic acid and hexamethyleneimine to an aqueous solution of sodium hydroxide, and stir to obtain solution B;

[0090] Step 1c: Add solution A dropwise to solution B (where n(SiO2):n(Al2O3):n(H2O) = 20:1:630, the molar ratio of hexamethyleneimine to sodium aluminate is 0.5738, and the molar ratio of sodium hydroxide to sodium aluminate is 3.98), stir thoroughly for 1 hour under nitrogen protection, and age at 60℃ for 10 hours; after aging, transfer to a crystallization reactor for the first crystallization treatment, crystallize at 140℃ for 7 days; after the first crystallization treatment, quench the reactor, add hexadecyltrimethylammonium bromide (CTAB), adjust the pH to 9-11, and then put it back into the crystallization reactor for the second crystallization treatment, crystallize at 110℃ for 7 days;

[0091] Step 1d: After crystallization, the reactor was quenched, the pH was adjusted to 7 again, and then dried at 130℃ for 3 hours. Finally, it was calcined in a muffle furnace at 500℃ for 6 hours to obtain the MCM-22 / MCM-41 composite molecular sieve. The mass ratio of MCM-22 to MCM-41 in the composite molecular sieve was 2:1, and the silica-alumina ratio was 10.

[0092] When the molar ratio of SiO2:Al2O3:H2O in the preparation method is 100:1:650, a composite molecular sieve with a silicon-to-aluminum ratio of 50 is obtained and named M-2. The mass ratio of MCM-22 and MCM-41 is 3:1.

[0093] When the molar ratio of SiO2:Al2O3:H2O in the preparation method is 180:1:700, a composite molecular sieve with a silicon-to-aluminum ratio of 90 is obtained and named M-3. The mass ratio of MCM-22 and MCM-41 is 4:1.

[0094] When the molar ratio of SiO2:Al2O3:H2O in the preparation method is 260:1:900, a composite molecular sieve with a silicon-to-aluminum ratio of 130 is obtained and named M-4. The mass ratio of MCM-22 and MCM-41 is 5:1.

[0095] (2) Preparation of zinc-modified composite molecular sieve catalysts

[0096] The composite molecular sieves (M-1, M-2, M-3, or M-4) were mixed with an aqueous solution of zinc nitrate using an equal-volume impregnation method. The mixture was stirred at low speed with a mechanical stirrer at room temperature until it became a paste. After standing for 24 hours, it was dried at 100°C for 12 hours in a forced-air drying oven. Then, it was placed in a muffle furnace and calcined at 500°C for 6 hours to obtain zinc-modified MCM-22 / MCM-41 composite molecular sieves. The Zn loading (wt%) based on the total weight of the catalyst was 3%, 6%, and 9%.

[0097] Example 1

[0098] Preparation method of diisopropylnaphthalene: Naphthalene and propylene are added to a reactor at a molar ratio of 1:2, stirred, and heated to 90°C and 2 MPa. 5% (by weight of total raw material) of Zn-modified M-1 molecular sieve catalyst (Zn loading 3 wt%) is added, and the reaction is carried out for 2 hours. After cooling to room temperature, the solid catalyst is removed by filtration to obtain crude diisopropylnaphthalene-type lubricating oil base oil. The crude diisopropylnaphthalene product is further distilled at 130–190°C, and the fraction obtained is the diisopropylnaphthalene product. The conversion rate of naphthalene is 99.8%, and the selectivity of diisopropylnaphthalene is 77%.

[0099] Catalyst cycling test: The zinc-modified molecular sieve obtained in Example 1 was reacted, filtered and recovered, and then recycled for catalytic use 5 times. The conversion rate and selectivity of each cycle were statistically analyzed. In the 5 cycles, the conversion rates of naphthalene were 98%, 99%, 99%, 99%, and 97%, respectively, and the selectivities of diisopropylnaphthalene were 76%, 75%, 74%, 74%, and 73%, respectively. This shows that the zinc-modified MCM-22 / MCM-41 composite molecular sieve provided by the present invention can be recycled multiple times, and the catalytic activity will not be significantly reduced.

[0100] Example 2

[0101] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified M-1 molecular sieve catalyst (Zn loading is 6wt%).

[0102] The conversion rate of naphthalene was 99.9%, and the selectivity of diisopropylnaphthalene was 78.2%.

[0103] Example 3

[0104] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified M-1 molecular sieve catalyst (Zn loading is 9wt%).

[0105] The conversion rate of naphthalene was 99.9%, and the selectivity of diisopropylnaphthalene was 76.3%.

[0106] Example 4

[0107] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified M-2 molecular sieve catalyst (Zn loading is 3wt%).

[0108] The conversion rate of naphthalene was 99.6%, and the selectivity of diisopropylnaphthalene was 78.3%.

[0109] Example 5

[0110] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified M-3 molecular sieve catalyst (Zn loading is 3wt%).

[0111] The conversion rate of naphthalene was 99.8%, and the selectivity of diisopropylnaphthalene was 76.1%.

[0112] Example 6

[0113] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified M-4 molecular sieve catalyst (Zn loading is 3wt%).

[0114] The conversion rate of naphthalene was 99.9%, and the selectivity of diisopropylnaphthalene was 74.5%.

[0115] Example 7

[0116] The method is basically the same as in Example 1, except that in the preparation method of diisopropylnaphthalene, the amount of Zn-modified M-1 molecular sieve catalyst (Zn loading of 3 wt%) added is 3% of the total mass of raw materials.

[0117] The naphthalene conversion rate was 99.8%, and the selectivity for diisopropylnaphthalene was 75.2%.

[0118] Example 8

[0119] The method is basically the same as in Example 1, except that in the preparation method of diisopropylnaphthalene, the amount of Zn-modified M-1 molecular sieve catalyst (Zn loading of 3wt%) added is 9% of the total mass of raw materials.

[0120] The naphthalene conversion rate was 99.9%, and the selectivity for diisopropylnaphthalene was 76.2%.

[0121] Example 9

[0122] The method is basically the same as in Example 1, except that the reaction temperature in the preparation method of diisopropylnaphthalene is 150°C.

[0123] The conversion rate of naphthalene was 99.9%, and the selectivity of diisopropylnaphthalene was 77.2%.

[0124] Comparative Example 1

[0125] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is M-1 molecular sieve that has not been modified by zinc.

[0126] The conversion rate of naphthalene was 99.8%, and the selectivity of diisopropylnaphthalene was 70%.

[0127] Comparative Example 2

[0128] The preparation method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified MCM-22 molecular sieve catalyst (Zn loading of 3 wt%), excluding MCM-41 molecular sieve. The MCM-22 molecular sieve is a commercially available product purchased from the Nankai University Catalyst Factory, with a silica-alumina ratio of 10.

[0129] The conversion rate of naphthalene was 99.2%, and the selectivity of diisopropylnaphthalene was 50.9%.

[0130] Comparative Example 3

[0131] The preparation method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is a Zn-modified MCM-41 molecular sieve catalyst (Zn loading of 3 wt%), excluding MCM-22 molecular sieve. The MCM-41 molecular sieve is a commercially available product purchased from the Nankai University Catalyst Factory, with a silica-alumina ratio of 10.

[0132] The conversion rate of naphthalene was 97%, and the selectivity of diisopropylnaphthalene was 38.5%.

[0133] Comparative Example 4

[0134] The method is basically the same as in Example 1, except that the catalyst added in the preparation method of diisopropylnaphthalene is M-1 molecular sieve catalyst modified with metallic titanium (Ti) (titanium loading is 3wt%).

[0135] The conversion rate of naphthalene was 95.2%, and the selectivity of diisopropylnaphthalene was 59%.

[0136] Comparative Example 5

[0137] The process is basically the same as in Example 1, except that the catalyst preparation process is as follows: MCM-22 and MCM-41 are mixed evenly at a mass ratio of 2:1, then mixed with zinc nitrate aqueous solution, and stirred at low speed with a mechanical stirrer at room temperature until a paste is formed. After standing for 24 hours, it is dried in a forced-air drying oven at 100°C for 12 hours, and then placed in a muffle furnace and calcined at 500°C for 6 hours to obtain the catalyst. The Zn loading is 3 wt% based on the total weight of the catalyst. The MCM-22 molecular sieve is a commercially available product from Nankai University Catalyst Factory, with a silicon-to-aluminum ratio of 10; the MCM-41 molecular sieve is also a commercially available product from Nankai University Catalyst Factory, with a silicon-to-aluminum ratio of 10.

[0138] The conversion rate of naphthalene was 99.3%, and the selectivity of diisopropylnaphthalene was 56%.

[0139] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A zinc-modified composite molecular sieve catalyst, characterized in that, The catalyst comprises zinc and a composite molecular sieve, wherein the composite molecular sieve is an MCM-22 / MCM-41 composite molecular sieve, and the zinc content is 1%-10% by mass based on the total weight of the zinc-modified composite molecular sieve catalyst.

2. The catalyst according to claim 1, characterized in that, In the MCM-22 / MCM-41 composite molecular sieve, the mass ratio of MCM-22 to MCM-41 is (2:1) to (5:1). Preferably, the silicon-to-aluminum ratio of the MCM-22 / MCM-41 composite molecular sieve is 10 to 130.

3. A method for preparing a catalyst according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Preparation of composite molecular sieves; Step 2: Obtain a mixture including the composite molecular sieve and the aqueous solution of the zinc precursor to obtain the zinc-modified composite molecular sieve catalyst.

4. The preparation method according to claim 3, characterized in that, Step 1 includes the following steps: Step 1a: Obtain a mixture including aluminum source and water, to obtain mixture A; Step 1b: Obtain a mixture including sodium hydroxide, silicon source, template agent, and water to obtain mixture B; Step 1c: Add mixture A to mixture B, age, and then perform a first crystallization treatment and a second crystallization treatment to obtain MCM-22 / MCM-41 composite molecular sieve.

5. The preparation method according to claim 3 or 4, characterized in that, In step 1, the silicon source, aluminum source, and water are mixed in a molar ratio of n(SiO2):n(Al2O3):n(H2O) = (20-260):1:(630-900); And / or, the molar ratio of template agent to aluminum source is (0.3-0.8):1, preferably (0.4-0.7):1, more preferably (0.5-0.6):1; And / or, the molar ratio of sodium hydroxide to aluminum source is (2-6):1, preferably (3-5):

1.

6. The preparation method according to any one of claims 3-5, characterized in that, In step 1c, the temperature of the first crystallization treatment is 130℃-150℃. And / or, in step 1c, the first crystallization treatment takes 5-8 days; And / or, in step 1c, the pH of the second crystallization treatment is 9-11. And / or, in step 1c, the temperature of the second crystallization treatment is 100–120°C. And / or, in step 1c, the second crystallization treatment takes 3-10 days.

7. The preparation method according to any one of claims 3-6, characterized in that, The silicon source includes at least one of silicic acid, water glass, and silica sol. And / or, the aluminum source includes at least one of sodium aluminate, sodium metaaluminate, and aluminum nitrate; And / or, the template agent includes at least one of hexamethyleneimine, tetraethylammonium hydroxide, and tetrabutylammonium bromide; And / or, the zinc-containing precursor includes at least one of zinc nitrate and zinc chloride.

8. The use of a catalyst according to any one of claims 1-2 or a catalyst prepared by any one of claims 3-7 in the preparation method of diisopropylnaphthalene.

9. A method for preparing diisopropylnaphthalene, characterized in that, The process includes the following steps: obtaining a mixture comprising naphthalene and propylene, adding a catalyst according to any one of claims 1-2 or a catalyst prepared by any one of claims 3-7, and reacting to obtain diisopropylnaphthalene.

10. The method for preparing diisopropylnaphthalene according to claim 9, characterized in that, The amount of zinc-modified composite molecular sieve catalyst added is 0.5% to 10% of the total mass of naphthalene and propylene; And / or, the reaction temperature is 90–240°C; And / or, the reaction pressure is 0.5–2 MPa; And / or, the molar ratio of naphthalene to propylene is 1:(2-2.2).