Binder-free MCM-22 molecular sieve as well as preparation method and application thereof

Abstract

The invention provides a binder-free MCM-22 molecular sieve as well as a preparation method and application thereof. Wherein the micropore specific surface area of the binderless MCM-22 molecular sieve is A m < 2 > / g, the total specific surface area of the binderless MCM-22 molecular sieve is B m < 2 > / g, and A and B meet the following relation: 50% < = (A / B) * 100% < = 90%. The MCM-22 molecular sieve is large in specific surface area and high in crystallinity, the mechanical strength is larger than 80 N / cm, and the MCM-22 molecular sieve is an MWW type molecular sieve of a lamellar structure and has good application prospects in the field of catalysis or adsorption.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve technology, specifically relating to a binder-free MCM-22 molecular sieve, its preparation method, and its application. Background Technology

[0002] MCM-22 molecular sieve is a type of molecular sieve material with MWW (Metal-Wheatstone Wollastonite) structure as its basic unit. It was synthesized by researchers at Mobil in 1990. Due to its excellent thermal and hydrothermal stability, unique acidity, and the presence of both twelve-membered and ten-membered ring channels, it can improve diffusion performance and enhance catalytic activity, making it important for industrial catalysis. In 1995, Exxon Mobil developed the EBMaxSM process for liquid-phase alkylation based on MCM-22 molecular sieve catalysts for the synthesis of ethylbenzene. The Mobil-Badger process uses MCM-22 molecular sieves as catalysts for the synthesis of cumene. Sinopec (Shanghai) Petrochemical Research Institute Co., Ltd. has developed an energy-saving, low-benzene-to-olefin ratio liquid-phase alkylation EBC series catalyst based on ultrathin layered MWW molecular sieves.

[0003] There are two main methods for synthesizing MCM-22: hydrothermal synthesis and vapor-phase synthesis. Most existing technologies employ the hydrothermal method. Hydrothermal synthesis can be further divided into dynamic and static hydrothermal methods, the difference being whether the mother liquor is rotated and stirred during crystallization. Vapor-phase synthesis, disclosed by Xu Wenyang, is a method for synthesizing zeolites where steam does not directly contact the solid-phase gel. The biggest advantages of vapor-phase synthesis are low template agent usage, high solid yield, avoidance of mother liquor dilution effect, and reduced emissions. Currently, this method has been successfully used to synthesize molecular sieves with various structures, including MFI, MOR, BEA, FER, and MWW.

[0004] However, molecular sieve products prepared by the above conventional methods are generally in powder form. When used as fixed-bed catalysts or adsorbents, inert binders need to be added to form them so that they have a certain mechanical strength. However, binders generally reduce the specific surface area of ​​the catalyst or adsorbent and reduce the number of active sites.

[0005] Vapor-phase synthesis is a technique for preparing binder-free molecular sieves. Liu Xingsheng et al. reported a method for preparing binder-free MCM-22 zeolite granular catalysts. This method mainly refers to vapor-phase synthesis, directly molding silicon-aluminum colloid particles from silicon source, aluminum source, and alkali. These particles are then placed on a support in a polytetrafluoroethylene reactor. A certain amount of a mixed solution of template agent HMI (hexamethyleneimine) and deionized water is weighed and placed at the bottom of the reactor. After crystallization, washing, filtering, drying, and calcination yield the product. However, this method requires a crystallization time of 168 hours to obtain MCM-22 molecular sieves with a large specific surface area, and the amount of template agent added is large, with an HMI / SiO2 molar ratio of at least 0.3, and the microporous specific surface area ratio is only 58%.

[0006] CN107511174A discloses a method for preparing binder-free MWW structured molecular sieve catalysts. This method converts the binder in the MWW structured molecular sieve catalyst precursor into MWW molecular sieves using acid to prepare binder-free MWW molecular sieves. The method has a relatively long HMI / SiO2 molar ratio of 0.5 and a crystallization time of 5 days, and the steps are relatively complex.

[0007] CN103771435A discloses a method for synthesizing MCM-22 molecular sieves. Under hydrothermal crystallization conditions, it utilizes the addition of two template agents: hexamethyleneimine and aniline. The molar ratio of hexamethyleneimine to aniline is less than 1.2, thus reducing the amount of hexamethyleneimine used. This method employs hydrothermal synthesis, and the synthesized molecular sieve product is in powder form.

[0008] Currently, the price of the template agent HMI required for the preparation of MCM-22 molecular sieves ranges from 50,000 to 100,000 yuan per ton, while the cost of silicon-aluminum is less than 10,000 yuan per ton. The template agent accounts for a large portion of the cost of molecular sieves, and the synthesis time is mostly over 5 days, resulting in high energy consumption costs. Therefore, it is necessary to find a method for preparing MCM-22 molecular sieves that can reduce the amount of template agent used, shorten the synthesis time, and reduce energy consumption costs. Summary of the Invention

[0009] To address the problems existing in the prior art, this application provides a binder-free MCM-22 molecular sieve, its preparation method, and its application.

[0010] In a first aspect, this application provides a binder-free MCM-22 molecular sieve, wherein the micropore specific surface area of ​​the binder-free MCM-22 molecular sieve is Am. 2 / g, the total specific surface area of ​​the binder-free MCM-22 molecular sieve is B m 2 / g, A and B satisfy the following relationship: 50% ≤ (A / B)×100% ≤ 90%, for example, (A / B)×100% is 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90% or any value between them.

[0011] In some implementations, 200 ≤ A ≤ 500, for example, A is 210, 230, 250, 270, 290, 310, 330, 350, 370, 390, 420, 450, 470, 490 or any value between them.

[0012] In some implementations, 300 ≤ A ≤ 500.

[0013] In some implementations, 400 ≤ B ≤ 550, for example, B is 420, 450, 470, 490, 510, 530, 550 or any value between them.

[0014] In some implementations, 50% ≤ (A / B) × 100% ≤ 80%; for example, (A / B) × 100% is 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, or any value between them.

[0015] In some implementations, 70% ≤ (A / B) × 100% ≤ 80%.

[0016] In some embodiments, the binder-free MCM-22 molecular sieve crystals have a plate-like morphology.

[0017] In some embodiments, the sheet-like morphology includes an interleaved sheet-like morphology.

[0018] In some embodiments, the thickness of the crystals of the binderless MCM-22 molecular sieve is 5nm-20nm, for example, 7nm, 10nm, 13nm, 16nm, 19nm or any value between them.

[0019] In some embodiments, the crystal length of the binderless MCM-22 molecular sieve is 100nm-500nm, for example, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm or any value between them.

[0020] In some embodiments, the crystal length of the binderless MCM-22 molecular sieve is 200 nm to 500 nm.

[0021] In some embodiments, the width of the binderless MCM-22 molecular sieve crystals is 100nm-500nm, for example, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm or any value between them.

[0022] In some embodiments, the total pore volume of the binder-free MCM-22 molecular sieve is 0.3 cm³. 3 / g-0.5cm 3 / g, for example, 0.3cm 3 / g, 0.32cm 3 / g, 0.34cm 3 / g, 0.36cm 3 / g, 0.38cm 3 / g, 0.4cm 3 / g, 0.42cm 3 / g, 0.44cm 3 / g, 0.46cm 3 / g, 0.48cm 3 / g, 0.5cm 3 / g or any value in between.

[0023] In some embodiments, the binder-free MCM-22 molecular sieve has a micropore volume of 0.15 cm³. 3 / g-0.3cm 3 / g, for example, 0.15cm 3 / g, 0.17cm 3 / g, 0.19cm 3 / g, 0.21cm 3 / g, 0.23cm 3 / g, 0.25cm 3 / g, 0.27cm 3 / g, 0.29cm 3 / g or any value in between.

[0024] In some embodiments, the mechanical strength of the binderless MCM-22 molecular sieve is 80 N / cm to 300 N / cm, for example, 80 N / cm, 100 N / cm, 120 N / cm, 140 N / cm, 160 N / cm, 180 N / cm, 200 N / cm, 220 N / cm, 240 N / cm, 260 N / cm, 280 N / cm, 300 N / cm or any value between them.

[0025] In some embodiments, the SiO2 / Al2O3 molar ratio of the binderless MCM-22 molecular sieve is 15-100, for example, 20, 30, 40, 50, 60, 70, 80, 90, 100 or any value between them.

[0026] In a second aspect, this application provides a method for preparing binder-free MCM-22 molecular sieves, comprising:

[0027] S1: A mixture including silicon source, aluminum source, alkali source, seed crystal, optional pore-forming agent and extrusion aid is mixed with template agent and solvent and then subjected to crystallization treatment to obtain crystallized product;

[0028] S2: The crystallized product is subjected to calcination treatment.

[0029] In some embodiments, the calcination temperature is 400°C-650°C, for example 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or any value between them.

[0030] In some embodiments, the calcination treatment time is 2h-6h, for example, 2h, 3h, 4h, 5h, 6h or any value between them.

[0031] In some embodiments, the preparation method includes the following steps:

[0032] A: A mixture including a silicon source, an aluminum source, an alkali source, a seed crystal, an optional pore-forming agent, and an extrusion aid is subjected to a first calcination treatment to obtain a crystallization precursor;

[0033] B: The crystallization precursor is mixed with a template agent and a solvent and then subjected to crystallization treatment to obtain the crystallized product;

[0034] C: The crystallized product is subjected to a second calcination treatment.

[0035] In some embodiments, the temperatures of the first calcination treatment and the second calcination treatment are each independently between 400°C and 650°C, for example, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or any value between them.

[0036] In some embodiments, the temperature of the second calcination treatment is 500°C-650°C.

[0037] In some embodiments, the first calcination treatment and the second calcination treatment are each independently 2h-6h, for example 2h, 3h, 4h, 5h, 6h or any value between them.

[0038] In some embodiments, the mechanical strength of the crystallized precursor is 120 N / cm to 300 N / cm, for example, 150 N / cm, 170 N / cm, 190 N / cm, 210 N / cm, 230 N / cm, 250 N / cm, 270 N / cm, 290 N / cm or any value between them.

[0039] In some embodiments, the atmosphere for the second roasting treatment is air.

[0040] In some embodiments, the crystallized product is washed and dried before undergoing a second calcination treatment.

[0041] In some embodiments, the washing may be done with water.

[0042] In some embodiments, the drying temperature is 60°C-150°C, for example 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or any value between them.

[0043] In some embodiments, the drying temperature is 80°C-120°C.

[0044] In some embodiments, the crystallization treatment temperature is 130°C-160°C, for example, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C or any value between them.

[0045] In some embodiments, the crystallization treatment is performed at a temperature of 140°C-150°C.

[0046] In some embodiments, the crystallization treatment time is 24h-120h, for example, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h, 70h, 75h, 80h, 85h, 90h, 95h, 100h, 105h, 110h, 115h, 120h or any value between them.

[0047] In some embodiments, the silicon source, aluminum source, alkali source, seed crystal, optional pore-forming agent, and extrusion aid are mixed and then subjected to molding treatment.

[0048] In some implementations, the molding process can be a kneading extrusion molding process or a ball rolling molding process.

[0049] In some embodiments, the silicon source is selected from one or more of silica gel powder, silica sol, silica fume, or water glass.

[0050] In some embodiments, the aluminum source is selected from one or more of aluminum nitrate, aluminum sulfate, sodium aluminate, or boehmite.

[0051] In some embodiments, the alkali source is NaOH and / or KOH.

[0052] In some embodiments, the alkali source is OH - The silicon source is calculated as SiO2, and OH... - / SiO2 molar ratio = 0.06-0.15, for example 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15 or any value between them.

[0053] In some embodiments, the aluminum source is based on Al2O3, the silicon source is based on SiO2, and the Al2O3 / SiO2 molar ratio is 0.01-0.1, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or any value between them.

[0054] In some embodiments, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the SiO2 / Al2O3 molar ratio is 10-50.

[0055] In some embodiments, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the SiO2 / Al2O3 molar ratio is 10-35.

[0056] In some embodiments, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the SiO2 / Al2O3 molar ratio is 15-30.

[0057] When the SiO2 / Al2O3 molar ratio is within the above range, the prepared MCM-22 molecular sieve exhibits better catalytic activity as a catalyst.

[0058] In some embodiments, the seed crystals are selected from MCM-22 molecular sieves, and the silicon-to-aluminum ratio of the seed crystals is 15-100, for example, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100 or any value between them, based on the molar ratio of SiO2 to Al2O3.

[0059] In some embodiments, the silicon source is SiO2, and the seed / SiO2 molar ratio is 0.01-0.15, for example, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14 or any value between them.

[0060] In some embodiments, the pore-forming agent is selected from one or more of polyethylene glycol, polyvinyl alcohol, or activated carbon powder.

[0061] In some embodiments, the extrusion aid is selected from one or more of guar gum powder, methylcellulose, hydroxypropylcellulose, or guar gum.

[0062] In some embodiments, the mass ratio of the pore-forming agent to the mixture is 0.001-0.01; for example, 0.002, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01 or any value between them.

[0063] In some embodiments, the mass ratio of the extrusion aid to the mixture is 0.001-0.02, for example, 0.002, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.012, 0.014, 0.016, 0.018 or any value between them.

[0064] In some embodiments, the template agent is selected from hexamethyleneimine (HMI).

[0065] In some embodiments, the total silicon content of the crystallization precursor is SiO2, and the molar ratio of the template agent to SiO2 is 0.1-0.4, for example, 0.1, 0.12, 0.15, 0.17, 0.2, 0.22, 0.25, 0.3, 0.35, 0.4 or any value between them.

[0066] In some embodiments, the total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of the template agent to SiO2 is 0.1-0.25.

[0067] In some embodiments, the total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of the template agent to SiO2 is 0.15-0.25.

[0068] In some embodiments, the solvent is selected from water.

[0069] In some embodiments, the total silicon content of the crystallization precursor is SiO2, and the molar ratio of solvent to SiO2 is 0.5-5, for example, 0.8, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or any value between them.

[0070] In some embodiments, the total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of solvent to SiO2 is 0.5-2.

[0071] In some embodiments, the total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of solvent to SiO2 is 1-2.

[0072] In some embodiments, the total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of solvent to SiO2 is 1-1.5.

[0073] In some embodiments, the binder-free MCM-22 molecular sieve prepared by the preparation method is the binder-free MCM-22 molecular sieve described in the first aspect.

[0074] In a third aspect, this application provides an application of the binderless MCM-22 molecular sieve described in the first aspect of this application or the binderless MCM-22 molecular sieve prepared by the preparation method described in the second aspect of this application in the fields of catalysis or adsorption.

[0075] In some embodiments, this application provides a binderless MCM-22 molecular sieve as described in the first aspect of this application or a binderless MCM-22 molecular sieve prepared by the preparation method described in the second aspect of this application as a catalyst for alkylation reactions and / or n-heptane cracking reactions.

[0076] Compared with the prior art, the present invention has the following superior effects:

[0077] (1) The binderless MCM-22 molecular sieve of the present invention has a large specific surface area, high crystallinity, and mechanical strength greater than 80 N / cm. It is a thin-plate structure MWW type molecular sieve with good application prospects in the fields of catalysis or adsorption. The binderless MCM-22 molecular sieve catalyst has excellent performance in alkylation and cracking reactions.

[0078] (2) The present invention directly synthesizes binder-free MCM-22 molecular sieve with certain mechanical strength in one step by using a vapor-phase dry gel conversion method. That is, a dry gel-state crystallization precursor is obtained by calcining silicon source, aluminum source, alkali source, seed crystal, optional pore-forming agent and extrusion aid. Then, the crystallization precursor is reacted under the action of template agent and water vapor to directly synthesize binder-free MCM-22 molecular sieve. This avoids the step of removing or converting binder after molecular sieve powder is formed in the traditional method, and simplifies the preparation process.

[0079] (3) By reducing the water / SiO2 molar ratio, the present invention reduces the amount of water used. Compared with the hydrothermal synthesis method in the prior art, the present invention effectively improves the product solid yield.

[0080] (4) The present invention adds a small amount of seed crystals in combination with dry glue conversion method, which shortens the crystallization time and helps to improve production efficiency.

[0081] (5) The present invention combines the above steps to reduce the amount of template agent used (HMI / SiO2) and significantly reduce the preparation cost. Attached Figure Description

[0082] Figure 1The image shows the XRD pattern of the binder-free MCM-22 molecular sieve of Example 1 of the present invention.

[0083] Figure 2 This is a SEM image of the binder-free MCM-22 molecular sieve of Example 1 of the present invention. Detailed Implementation

[0084] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0085] 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.

[0086] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0087] In this invention, the specific surface area and pore volume of the catalyst are terms known in the art and can be tested using methods and instruments known in the art. Specifically, an ASAP2020M physicochemical adsorption instrument from Micron Instruments (USA) was used. Before measurement, the sample was evacuated and treated at 300°C for 2 hours to remove impurities adhering to the sample surface. Then, high-purity N2 was adsorbed at low temperature using liquid nitrogen to obtain the adsorption / desorption curve of the catalyst powder. The specific surface area was calculated using the BET method, and the pore volume was calculated using the BJH method.

[0088] In this invention, the mechanical strength of the catalyst has a meaning known in the art and can be tested using methods and instruments known in the art. Specifically, the catalyst strength is determined using a DLⅢ type intelligent particle strength testing machine produced by Dalian Chemical Research and Design Institute. The measurement is performed 22 times, and the maximum and minimum values ​​are removed before taking the average value.

[0089] In this invention, XRD was performed using a Bruker D-8 Advance X-ray diffractometer, with Cu K radiation as the X-ray source. Graphite monochromator, tube voltage 40kV, tube current 40mA, diffraction range 5°-50°.

[0090] In this invention, the analysis of the microstructure, structure, and grain size of the samples was performed using an XL30E scanning electron microscope from FEI Corporation, USA, with a magnification of 20,000 to 80,000 times and an accelerating voltage of 50V to 30kV.

[0091] In this invention, the chemical composition of the sample, i.e. the silicon-to-aluminum ratio, was determined using an X-ray fluorescence spectrometer, specifically a Bruker S4 Pioneer instrument.

[0092] In this invention, catalyst evaluation and product analysis were performed using a self-built chromatographic pulsed microreactor. The binder-free MCM-22 catalyst was pulverized, and particles of 20-30 mesh size were sieved and packed into the 0.20 mL gas chromatograph injection port liner. The pressure was at atmospheric pressure, and the reaction temperature was controlled by varying the injection port temperature. The instrument used was an Agilent 7890A, with an autosampler pulse injection volume of 0.2 μL, a split ratio of 150:1, an HP-5 column, and an FID detector. Routine analysis of the reaction products was sufficient. Conversion and selectivity were calculated in molar terms.

[0093] In this invention, the alkylation reaction refers to the alkylation of benzene and isopropanol. The reaction pressure is atmospheric pressure, the feed molar ratio of benzene to isopropanol is 4:1, the conversion rate refers to the conversion rate of isopropanol, and the selectivity is the selectivity of the main product cumene calculated in molar. The performance of the catalyst is evaluated by the conversion rate of isopropanol and the selectivity of cumene.

[0094] In this invention, the n-heptane reaction refers to the cracking of n-heptane under a nitrogen atmosphere. The main products of the reaction are low-carbon alkanes, alkenes, etc. The performance of the catalyst is evaluated by the conversion rate of n-heptane.

[0095] Unless otherwise specified, the mixtures in the embodiments of the present invention refer to "seed crystals / SiO2, SiO2 / Al2O3, and total Na". + In " / SiO2", SiO2 refers to the total SiO2 content (in moles) in the silicon source. "Total Na" + Total Na in " / SiO2" + The total Na content in the mixture + Content (in moles).

[0096] Unless otherwise specified, in the process of preparing crystallized products in the embodiments of the present invention, "HMI / SiO2, water / SiO2" refers to the total SiO2 content (in moles) in the crystallization precursor.

[0097] In this invention, "solid yield" refers to the ratio of the final molecular sieve product's mass to all the inorganic raw materials fed into the solution. Compared to the existing liquid-phase synthesis method, where some silicon and aluminum sources dissolve in the solution, resulting in losses, the solid-phase synthesis method of this invention effectively avoids the losses caused by the dissolution of silicon and aluminum sources.

[0098] In this invention, the dimensions of the MCM-22 molecular sieve are defined as follows: length is defined as the length of the longest side of the crystal, width is defined as the length of the second longest side of the crystal, and thickness is defined as the length of the shortest side of the crystal.

[0099] In this embodiment of the invention, the crystal thickness of the MCM-22 molecular sieve is 5nm-20nm.

[0100] Example 1

[0101] a) A mixture is obtained by extruding a silicon source (silica gel powder, silica sol), sodium aluminate, NaOH, MCM-22 molecular sieve seed crystals (silicon-to-aluminum ratio of 30), hydroxypropyl methylcellulose, and guar gum powder. The seed crystal / SiO2 molar ratio is 0.1. Based on molar ratio, the SiO2 in the silica gel powder accounts for 40% of the total SiO2 in the silicon source, and the SiO2 in the silica sol accounts for 60% of the total SiO2 in the silicon source. The sodium aluminate is added according to a SiO2 / Al2O3 molar ratio of 30. The total NaOH content is... + The molar ratio of SiO2 is 0.08, the amount of hydroxypropyl methylcellulose added is 0.5% of the mass of the mixture, and the amount of guar gum added is 0.5% of the mass of the mixture.

[0102] b) The above mixture was calcined at 550°C in air for 4 hours to obtain a crystallized precursor with a mechanical strength of 153.2 N / cm.

[0103] c) The crystallization precursor obtained in step b) is placed in a rotary crystallization vessel with template agent (HMI) and water for crystallization. The crystallization precursor reacts under the action of water and template agent vapor. The crystallization temperature is 145℃ and the crystallization time is 72h to obtain the crystallized product. The molar ratio of HMI / SiO2 is 0.24 and water / SiO2 is 1.2.

[0104] d) After washing the crystallized product from step c) with water and drying it at 120°C, it is then calcined at 580°C in air for 4 hours to obtain binder-free MCM-22 molecular sieve.

[0105] Figure 1 This is the XRD pattern of the MCM-22 molecular sieve. It can be seen that the MCM-22 molecular sieve has a high degree of crystallinity. Figure 2This is a SEM image of the MCM-22 molecular sieve. It can be seen that the MCM-22 molecular sieve synthesized in this embodiment has a plate-like microstructure, good crystallinity, no amorphous substances, and staggered growth, ensuring that the molecular sieve product has a certain mechanical strength. The yield of solids in the preparation was 98%, and the total specific surface area of ​​the obtained MCM-22 molecular sieve was 507.4 m². 2 / g, of which the microporous specific surface area is 399.6m² 2 / g, total pore volume 0.45cm³ 3 / g, micropore volume is 0.20cm³ 3 / g, with a mechanical strength of 102 N / cm, as shown in Table 1.

[0106] Example 2

[0107] The binderless MCM-22 molecular sieve obtained in Example 1 was exchanged three times with a 10wt% ammonium acetate aqueous solution and then calcined in air at 580°C to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. Its alkylation performance is evaluated as shown in Table 2, and its n-heptane cracking performance is evaluated as shown in Table 3.

[0108] Example 3

[0109] Unlike Example 1, HMI / SiO2 = 0.18, and the characterization results of the prepared MCM-22 molecular sieve are shown in Table 1.

[0110] Example 4

[0111] The binderless molecular sieve obtained in Example 3 was exchanged three times with a 10wt% ammonium acetate aqueous solution and then calcined in air at 580°C to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 4 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 4 is evaluated as shown in Table 3.

[0112] Example 5

[0113] Unlike Example 1, the SiO2 / Al2O3 molar ratio of the feed was 20, and the characterization results of the prepared MCM-22 molecular sieve are shown in Table 1.

[0114] Example 6

[0115] The binderless molecular sieve obtained in Example 5 was exchanged three times with a 10wt% ammonium acetate aqueous solution and then calcined in air at 580°C to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 6 is evaluated as shown in Table 2. The n-heptane cracking catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 6 is evaluated as shown in Table 3.

[0116] Example 7

[0117] Unlike Example 1, HMI / SiO2 = 0.12. The characterization results are shown in Table 1.

[0118] Example 8

[0119] The binderless molecular sieve obtained in Example 7 was exchanged three times with a 10 wt% ammonium acetate aqueous solution, and then calcined at 580°C in air to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 8 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 8 is evaluated as shown in Table 3.

[0120] Example 9

[0121] Unlike Example 1, the water / SiO2 ratio was 0.8. The characterization results are shown in Table 1.

[0122] Example 10

[0123] The binderless molecular sieve obtained in Example 9 was exchanged three times with a 10 wt% ammonium acetate aqueous solution and then calcined in air at 580°C to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 10 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 10 is evaluated as shown in Table 3.

[0124] Example 11

[0125] Unlike Example 1, the SiO2 / Al2O3 molar ratio was 10. The characterization results are shown in Table 1.

[0126] Example 12

[0127] The binderless molecular sieve obtained in Example 11 was exchanged three times with a 10 wt% ammonium acetate aqueous solution, and then calcined at 580°C in air to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 12 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 12 is evaluated as shown in Table 3.

[0128] Example 13

[0129] Unlike Example 1, the SiO2 / Al2O3 molar ratio was 50. The characterization results are shown in Table 1.

[0130] Example 14

[0131] The binderless molecular sieve obtained in Example 13 was exchanged three times with a 10 wt% ammonium acetate aqueous solution, and then calcined at 580°C in air to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 14 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 14 is evaluated as shown in Table 3.

[0132] Example 15

[0133] Unlike Example 1, the crystallization temperature was 160°C. The characterization results are shown in Table 1.

[0134] Example 16

[0135] The binderless molecular sieve obtained in Example 15 was exchanged three times with a 10 wt% ammonium acetate aqueous solution and then calcined in air at 580°C to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 16 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 16 is evaluated as shown in Table 3.

[0136] Example 17

[0137] Unlike Example 1, the crystallization temperature was 130°C and the crystallization time was 144 h. The characterization results are shown in Table 1.

[0138] Example 18

[0139] The binderless molecular sieve obtained in Example 17 was exchanged three times with a 10 wt% ammonium acetate aqueous solution and then calcined at 580°C in air to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 18 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 18 is evaluated as shown in Table 3.

[0140] Example 19

[0141] Unlike Example 1, in step a), the total Na + The molar ratio of SiO2 to SiO2 was 0.15, and the crystallization time was 48 h. The characterization results are shown in Table 1.

[0142] Example 20

[0143] The binderless molecular sieve obtained in Example 19 was exchanged three times with a 10 wt% ammonium acetate aqueous solution and then calcined in air at 580°C to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 20 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 20 is evaluated as shown in Table 3.

[0144] Example 21

[0145] Unlike Example 1, in step a), the total Na + The molar ratio of SiO2 to SiO2 was 0.05, and the crystallization time was 144 h. The characterization results are shown in Table 1.

[0146] Example 22

[0147] The binderless molecular sieve obtained in Example 21 was exchanged three times with a 10 wt% ammonium acetate aqueous solution, and then calcined at 580°C in air to obtain the H-MCM-22 binderless zeolite molecular sieve catalyst. The alkylation catalytic performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 22 is evaluated as shown in Table 2, and the n-heptane cracking performance of the H-MCM-22 binderless zeolite molecular sieve catalyst prepared in Example 22 is evaluated as shown in Table 3.

[0148] Comparative Example 1

[0149] A mixture of silicon source (silica powder, silica sol), sodium aluminate, NaOH, MCM-22 molecular sieve seed crystals (silicon-to-aluminum ratio of 30), template agent (HMI), and water was stirred until homogeneous, resulting in a mixture with a seed crystal / SiO2 molar ratio of 0.1. Molarly, the SiO2 in the silica powder accounted for 40% of the total SiO2 in the silicon source, and the SiO2 in the silica sol accounted for 60% of the total SiO2 in the silicon source. The sodium aluminate was added according to a SiO2 / Al2O3 molar ratio of 30, and the total NaOH content was... + The molar ratio of HMI / SiO2 is 0.08, and the molar ratios of HMI / SiO2 are 0.4 and water / SiO2 = 60. The resulting mixture is placed in a rotary crystallizer for crystallization at 145℃ for 120 hours to obtain the crystallized product. The crystallized product is washed and calcined at 580℃ to obtain conventional MCM-22 molecular sieve powder.

[0150] The conventional MCM-22 molecular sieve powder was exchanged three times with a 10wt% ammonium acetate aqueous solution and calcined at 580℃ to obtain H-MCM-22 powder. The powder was then mixed with boehmite (measured as alumina) at a mass ratio of 8:2 and kneaded into a molten shape. After calcination at 580℃ in air for 4 hours, a binder-bonded H-Al-MCM-22 molecular sieve catalyst was obtained. The characterization results are shown in Table 1, the alkylation catalytic performance evaluation is shown in Table 2, and the n-heptane cracking catalytic performance evaluation is shown in Table 3.

[0151] Comparative Example 2

[0152] Unlike Comparative Example 1, sodium aluminate was added according to a SiO2 / Al2O3 molar ratio of 20 to obtain a binder-bonded H-Al-MCM-22 molecular sieve catalyst. The characterization results are shown in Table 1, the alkylation catalytic performance evaluation is shown in Table 2, and the n-heptane cracking catalytic performance evaluation is shown in Table 3.

[0153] Comparative Example 3

[0154] (1) Preparation of the silica-alumina gel matrix: Weigh the silicon source (silica powder, silica sol) to prepare solution A, and prepare an equal volume of solution B with aluminum source and NaOH. Mix solution A and solution B and stir thoroughly to prepare SiO2:Al2O3:Na + A sol with a molar ratio of 30:1:2.7 was prepared by adding nitric acid to adjust the pH of the sol. The sol was then aged at 80°C with stirring. After aging for 10 hours, the silica-alumina gel was dried at 120°C for 12 hours to obtain dry silica-alumina gel.

[0155] (2) Matrix molding: The above-mentioned silicon-aluminum dry powder is mixed evenly with deionized water, nitric acid and guar gum powder in a high-speed mixer, extruded on an extruder, and dried at 120°C for 12 hours to obtain silicon-aluminum glue matrix particles.

[0156] (3) The above-mentioned silica-alumina matrix particles were placed on a support inside a polytetrafluoroethylene reactor. A mixed solution of template agent HMI and deionized water was weighed and placed at the bottom of the reactor, with HMI / SiO2 = 1 and water / SiO2 = 5. After sealing the reactor, it was crystallized at 150℃ for 168h and then removed to obtain an intermediate product. The intermediate product was washed, filtered, dried at 120℃ for 12h, and then calcined at 540℃ for 8h to obtain the final product. The characterization results are shown in Table 1.

[0157] (4) The above powder product is calcined with ammonium nitrate aqueous solution at 580°C to obtain H-MCM-22 powder. The above powder is mixed with boehmite (measured as alumina) at a mass ratio of 8:2 and kneaded into shape. After calcination at 580°C in air atmosphere for 4 hours, H-Al-MCM-22 molecular sieve catalyst with binder is obtained. The characterization results are shown in Table 1. The alkylation catalytic performance evaluation is shown in Table 2. The n-heptane cracking catalytic performance evaluation is shown in Table 3.

[0158] Catalyst evaluation

[0159] The molecular sieve catalysts prepared in the above examples and comparative examples were used for alkylation reactions. The gauge pressure of the reaction was atmospheric pressure, and the feed molar ratio of benzene to isopropanol was 4:1. The conversion rate refers to the conversion rate of isopropanol, while the selectivity is the selectivity of the main product cumene calculated in moles. The performance of the catalyst was evaluated by the conversion rate of isopropanol and the selectivity of cumene (both calculated in moles), and the results are shown in Table 2.

[0160] The molecular sieve catalysts prepared in the above examples and comparative examples were used for the n-heptane reaction. The gauge pressure of the reaction was atmospheric pressure, and pure n-heptane was fed. The main products of the reaction were low-carbon alkanes, alkenes, etc. The performance of the catalyst was evaluated by the conversion rate of n-heptane (in moles), and the results are shown in Table 3.

[0161] Table 1

[0162]

[0163]

[0164]

[0165] The products in Table 1 refer to the MCM-22 molecular sieve or H-MCM-22 molecular sieve catalyst prepared in the examples, or the H-Al-MCM-22 molecular sieve catalyst prepared in the comparative examples.

[0166] The product microscale in Table 1 refers to the crystal length and crystal width of MCM-22 molecular sieve or H-MCM-22 molecular sieve catalyst, both of which are between 100 nm and 500 nm.

[0167] Table 2

[0168]

[0169]

[0170] Table 3

[0171]

[0172]

[0173] The molecular sieve of this invention belongs to the binder-free zeolite molecular sieve category, exhibiting high crystallinity, a high micropore specific surface area ratio, and high mechanical strength. As can be seen from the examples and comparative examples, this invention can reduce the amount of template agent and water used in the preparation of MCM-22 molecular sieve.

[0174] Furthermore, after the molecular sieve of the present invention is treated with ammonium ion exchange to form H-MCM-22 molecular sieve, it can be used as a catalyst for alkylation reactions with high conversion rate and high selectivity for cumene; it also has a high conversion rate in the cracking reaction of n-heptane, and is a type of catalytic material that can be used as a solid acid.

[0175] According to Examples 7-8 and Examples 15-16 of the present invention, if the HMI / SiO2 content is too low or the crystallization temperature is too high, impurities will be generated in the synthesized MCM-22 molecular sieve.

[0176] As can be seen from Examples 17-18 of the present invention, lowering the crystallization temperature requires extending the crystallization time.

[0177] According to Examples 9-10 of the present invention, if the water / SiO2 content is too low, the crystallinity of the resulting MCM-22 molecular sieve will decrease, affecting its catalytic performance.

[0178] According to embodiments 19-22 of the present invention, total Na + A higher molar ratio of Na / SiO2 can shorten the crystallization time, while the total Na... + If the molar ratio of SiO2 decreases, the crystallization time needs to be extended.

[0179] Furthermore, compared with Comparative Example 3, the present invention can significantly reduce the amount of template agent and water and significantly shorten the crystallization reaction time. Moreover, compared with Comparative Example 3, the H-MCM-22 binder-free molecular sieve in the embodiments of the present invention can significantly improve the n-heptane cracking conversion rate in the catalytic n-heptane cracking reaction.

[0180] 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 binder-free MCM-22 molecular sieve, wherein, The specific surface area of ​​the micropores in the binder-free MCM-22 molecular sieve is Am. 2 / g, the total specific surface area of ​​the binder-free MCM-22 molecular sieve is B m 2 / g, A and B satisfy the following relationship: 50% ≤ (A / B) × 100% ≤ 90%.

2. The binder-free MCM-22 molecular sieve according to claim 1, characterized in that, 200≤A≤500, and / or 400≤B≤550, and / or 50%≤(A / B)×100%≤80%.

3. The binder-free MCM-22 molecular sieve according to claim 1 or 2, characterized in that, The binder-free MCM-22 molecular sieve crystals have a plate-like morphology, preferably including an interlaced plate-like morphology; and / or The thickness of the binderless MCM-22 molecular sieve crystals is 5nm-20nm; and / or The binderless MCM-22 molecular sieve has crystals with a length of 100 nm to 500 nm; preferably 200 nm to 500 nm; and / or The width of the MCM-22 molecular sieve crystals is 100nm-500nm.

4. The binder-free MCM-22 molecular sieve according to any one of claims 1-3, characterized in that, The total pore volume of the binder-free MCM-22 molecular sieve is 0.3 cm³. 3 / g-0.5cm 3 / g; and / or The binder-free MCM-22 molecular sieve has a micropore volume of 0.15 cm³. 3 / g-0.3cm 3 / g; and / or The binder-free MCM-22 molecular sieve has a mechanical strength of 80 N / cm-300 N / cm; and / or The SiO2 / Al2O3 molar ratio of the binder-free MCM-22 molecular sieve is 15-100.

5. A method for preparing binder-free MCM-22 molecular sieve, comprising: S1: A mixture including silicon source, aluminum source, alkali source, seed crystal, optional pore-forming agent and extrusion aid is mixed with template agent and solvent and then subjected to crystallization treatment to obtain crystallized product; S2: The crystallized product is subjected to calcination treatment; Preferably, the calcination temperature is 400℃-650℃; and / or The roasting process takes 2-6 hours.

6. The preparation method according to claim 5, characterized in that, The preparation method includes the following steps: A: A mixture including a silicon source, an aluminum source, an alkali source, a seed crystal, an optional pore-forming agent, and an extrusion aid is subjected to a first calcination treatment to obtain a crystallization precursor; B: The crystallization precursor is mixed with a template agent and a solvent and then subjected to crystallization treatment to obtain the crystallized product; C: The crystallized product is subjected to a second calcination treatment; Preferably, the temperatures of the first calcination treatment and the second calcination treatment are each independently between 400°C and 650°C; Preferably, the temperature of the second calcination treatment is 500℃-650℃; and / or The first calcination treatment and the second calcination treatment each have a duration of 2-6 hours; and / or The mechanical strength of the crystallized precursor is 120 N / cm-300 N / cm; and / or The atmosphere for the second calcination treatment is air; and / or Before subjecting the crystallized product to a second calcination treatment, the crystallized product is first washed and dried; and / or The crystallization treatment temperature is 130℃-160℃, preferably 140℃-150℃; and / or The crystallization process takes 24-120 hours.

7. The preparation method according to claim 5 or 6, characterized in that, The silicon source is selected from one or more of silica gel powder, silica sol, silica fume, or water glass; and / or The aluminum source is selected from one or more of aluminum nitrate, aluminum sulfate, sodium aluminate, or boehmite; and / or The alkali source is NaOH and / or KOH; and / or The alkaline source is OH - The silicon source is calculated as SiO2, and OH... - / SiO2 molar ratio = 0.06-0.15; and / or The aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the Al2O3 / SiO2 molar ratio is 0.01-0.1; and / or The seed crystals are selected from MCM-22 molecular sieves, and the silicon-to-aluminum ratio of the seed crystals is 15-100, based on the molar ratio of SiO2 to Al2O3. Preferably, the silicon source is SiO2, and the seed / SiO2 molar ratio is 0.01-0.

15.

8. The preparation method according to any one of claims 5-7, characterized in that, The pore-forming agent is selected from one or more of polyethylene glycol, polyvinyl alcohol, or activated carbon powder, and / or The extrusion aid is selected from one or more of guar gum powder, methylcellulose, hydroxypropylcellulose, or guar gum, and / or The mass ratio of the pore-forming agent to the mixture is 0.001-0.01; and / or The mass ratio of the extrusion aid to the mixture is 0.001-0.

02.

9. The preparation method according to any one of claims 6-8, characterized in that, The template agent is selected from hexamethyleneimine. Preferably, the total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of the template agent to SiO2 is 0.1-0.4, preferably 0.1-0.25, more preferably 0.15-0.25; and / or, the solvent is selected from water, and / or The total silicon content of the crystallization precursor is calculated as SiO2, and the molar ratio of solvent to SiO2 is 0.5-5, preferably 0.5-2.

10. The application of a binderless MCM-22 molecular sieve according to any one of claims 1-4 or a binderless MCM-22 molecular sieve prepared by any one of claims 5-9 in the fields of catalysis or adsorption.

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