MCM-22 molecular sieve with high specific surface area as well as preparation method and application of MCM-22 molecular sieve

Abstract

The invention relates to the technical field of molecular sieve preparation, and provides an MCM-22 molecular sieve with a high specific surface area, and a preparation method and application thereof. The specific surface area of the MCM-22 molecular sieve is greater than 500m < 2 > g <-1 >, and the external specific surface area is greater than 150m < 2 > g <-1 >. The MCM-22 molecular sieve provided by the invention has relatively high specific surface area and external specific surface area, has relatively good accessibility of active sites, and can have relatively good catalytic activity when being used as a catalyst; the preparation method is simple and easy to operate, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molecular sieve preparation, and more particularly to a MCM-22 molecular sieve with high specific surface area and a preparation method and application thereof. BACKGROUND

[0002] The MCM-22 molecular sieve has two independent pore systems: one is a sinusoidal 10-membered ring two-dimensional pore with a pore size of 0.4*0.59 nm; and the other is a 0.71*1.82 nm 12-membered ring supercage, which is connected by the 10-membered ring, and the MCM-22 molecular sieve also has a bowl-shaped 12-membered ring half-supercage on the outer surface. The MCM-22 molecular sieve exhibits high selectivity and strong adsorption capacity due to its unique pore system, but the MCM-22 molecular sieve synthesized by using hexamethylene imine as a template through hydrothermal synthesis generally has a particle diameter of about 2 μm and a thickness of about 0.1 μm, and the flaky particles may aggregate to form several-micron spherical aggregates, thereby resulting in that the accessibility of active sites in the MCM-22 molecular sieve is not ideal. Since the thickness of the flaky layer and the dispersion of the particles directly affect the accessibility of the active sites in the molecular sieve, the prior art mainly changes the morphology and particle size of the MCM-22 molecular sieve by changing the synthesis conditions of the molecular sieve or using post-synthesis treatment, so as to improve the reaction activity of the molecular sieve catalyst. However, the above methods are relatively complex, which greatly increases the difficulty of the preparation process of the molecular sieve. Therefore, it is very meaningful to develop a simple and easy-to-operate preparation method of the MCM-22 molecular sieve with good accessibility of active sites. SUMMARY

[0003] The present application aims to provide a MCM-22 molecular sieve with high specific surface area and a preparation method and application thereof, so as to solve the technical problem of the MCM-22 molecular sieve in the prior art that the accessibility of active sites is not ideal due to the excessively large particle size or serious aggregation of particles.

[0004] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a MCM-22 molecular sieve with high specific surface area, which has a specific surface area S BET > 500 m 2 g -1 , and an external specific surface area Sext > 150 m 2 g -1 .

[0006] According to some embodiments of the present application, the specific surface area S BET of the MCM-22 molecular sieve is 520-600 m 2 g -1 .

[0007] According to some embodiments of the present application, the MCM-22 molecular sieve has an external specific surface area S ext is 160-200 m 2 g -1 .

[0008] In the present application, the specific surface area of the molecular sieve refers to the total specific surface area including the internal specific surface area and the external specific surface area.

[0009] Generally, the greater the specific surface area and the external specific surface area of the molecular sieve, the better the accessibility of the active sites of the molecular sieve; in particular, the external specific surface area of the molecular sieve is directly proportional to the accessibility of the active sites of the molecular sieve, and the greater the value, the more the acid active sites of the molecular sieve are exposed.

[0010] In a second aspect, the present application provides a preparation method of the MCM-22 molecular sieve with high specific surface area, comprising: obtaining a mixed solution comprising a silicon source, an aluminum source, an alkali source, a solvent, an organic template agent and an additive, performing crystallization treatment on the mixed solution, and then calcining the crystallization product to obtain the MCM-22 molecular sieve with high specific surface area.

[0011] The additive is selected from a compound containing a six-membered ring structure and an amide group, and the six-membered ring structure includes a piperidyl group or a phenyl group.

[0012] In the preparation method provided by the present application, the added additive can fill the molecular sieve framework, and has a certain inhibitory effect on the stacking of the MCM-22 sheet-shaped crystals, so that the MCM-22 molecular sieve with greater specific surface area and external specific surface area can be obtained.

[0013] According to some embodiments of the present application, the additive includes at least one of piperidine-4-formamide, 1-methylpiperidine-4-formamide, 1-ethylpiperidine-4-formamide, 4-acetylamino piperidine, 4-acetylaminoethyl piperidine, 4-acetylamino-2, 2, 6, 6-tetramethyl-1-piperidinol, 2-phenylacetamide, 4-amino-N-methylbenzamide, and p-aminobenzamide.

[0014] According to some embodiments of the present application, the silicon source includes at least one of silica sol, tetraethyl orthosilicate, white carbon black, and water glass.

[0015] According to some embodiments of the present application, the aluminum source includes at least one of aluminum sol, pseudo-boehmite, aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, and aluminum oxide.

[0016] According to some embodiments of the present application, the alkali source includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

[0017] According to some embodiments of the present application, the solvent comprises at least one of water, methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, diethylene glycol, glycerol, diglycerol.

[0018] According to some embodiments of the present application, the organic template comprises at least one of hexamethyleneimine, piperidine, piperazine, homopiperazine, cyclohexylamine, diethylcyclohexylamine, dicyclohexylamine, ethanolamine.

[0019] According to some embodiments of the present application, the molar ratio of the raw materials is: SiO2 / Al2O3 = 20-100, OH - / SiO2 = 0.01-1, OSDA / SiO2 = 0.01-0.8, R / SiO2 = 0.05-0.8, I / SiO2 = 3-300, based on SiO2 for the silicon source, Al2O3 for the aluminum source, OH - / SiO2 for the alkali source, OSDA for the organic template, and R for the additive, and I for the solvent.

[0020] According to some embodiments of the present application, SiO2 / Al2O3 = 35-80.

[0021] According to some embodiments of the present application, OH - / SiO2 = 0.1-0.4.

[0022] According to some embodiments of the present application, OSDA / SiO2 = 0.15-0.3.

[0023] According to some embodiments of the present application, R / SiO2 = 0.1-0.5.

[0024] According to some embodiments of the present application, I / SiO2 = 20-50.

[0025] According to some embodiments of the present application, the temperature of the crystallization treatment is 100-200°C, preferably 140-180°C; and the time of the crystallization treatment is 2-200h, preferably 24-144h, more preferably 60-120h.

[0026] According to some embodiments of the present application, the temperature of the calcination is 400-700°C, preferably 500-600°C; and the time of the calcination is 0.5-8h, preferably 4-6h.

[0027] According to some embodiments of the present application, the calcination is performed in air.

[0028] According to some embodiments of the present application, the crystallization product is cooled, filtered, washed, dried, and then calcined.

[0029] According to some embodiments of the present application, the drying temperature is 50-150℃, preferably 80-120℃; and the drying time is 0.5-48h, preferably 4-24h.

[0030] In a third aspect, the present application provides a high specific surface area MCM-22 molecular sieve, which is prepared by the method of the second aspect.

[0031] According to some embodiments of the present application, the high specific surface area MCM-22 molecular sieve has a specific surface area S BET > 500m 2 g -1 and an external specific surface area Sext > 150m 2 g -1 .

[0032] According to some embodiments of the present application, the high specific surface area MCM-22 molecular sieve has a specific surface area S BET of 520-600m 2 g -1 .

[0033] According to some embodiments of the present application, the high specific surface area MCM-22 molecular sieve has an external specific surface area Sext of 160-200m 2 g -1 .

[0034] In a fourth aspect, the present application provides the use of the high specific surface area MCM-22 molecular sieve of the first or third aspect in the field of catalysts.

[0035] The present application has at least the following beneficial effects:

[0036] The MCM-22 molecular sieve provided by the present application has a high specific surface area and external specific surface area, and good accessibility of active sites, and can have good catalytic activity when used as a catalyst; the preparation method is simple and easy to operate, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 XRD diffraction pattern of the MCM-22 molecular sieve prepared in Example 1. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with specific examples. It should be understood that the specific examples described herein are only used to illustrate the present application in detail, and do not limit the protection scope of the present application in any way.

[0039] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present application belongs. The reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the raw materials, instruments and equipment used in the following examples can be purchased on the market or obtained by existing methods; the reagent usage is conventional unless otherwise specified; and the experimental methods are conventional unless otherwise specified.

[0040] In the various embodiments and comparative examples of the present application, each performance data is tested according to the following test methods:

[0041] (1) XRD phase analysis: measured by a D8 Focus diffractometer of Bruker Company, graphite monochromator, Cu target Kα ray light source, wavelength λ of 0.154 nm, 40 kV tube voltage, 40 mA tube current, and diffraction signals recorded in a 2θ range of 3-90° (2° / min scanning speed).

[0042] (2) Specific surface area and external specific surface area: low-temperature N2 adsorption-desorption analysis of the sample is performed by a Tristar 3000 specific surface analyzer produced by Micrometrics Company. The sample is pretreated by vacuum activation at 300°C for 6 h before testing, the testing temperature is -196°C, and the specific surface area and external specific surface area data of the tested sample are obtained by analyzing the isotherm.

[0043] Example 1

[0044] Dissolve the silica sol, sodium aluminate, hexamethylene imine, 2-phenylacetamide, and sodium hydroxide in water, stir uniformly to obtain a mixed solution, the molar ratio of each component in the mixed solution is SiO2:0.02Al2O3:0.25OSDA:0.15R:0.2NaOH:50H2O; pour the mixed solution into a polytetrafluoroethylene-lined pressure steel kettle, and crystallize at 170°C for 4 days. After crystallization, naturally cool to room temperature, filter and wash the crystallization product, dry at 100°C for 8 h, and finally calcine at 550°C in air for 5 h to remove the template agent used, to obtain a molecular sieve.

[0045] The XRD pattern of the molecular sieve prepared in this example is shown in Figure 1 It can be seen that it is a MCM-22 molecular sieve.

[0046] The test results of the specific surface area and external specific surface area of the molecular sieve prepared in this example are shown in Table 1.

[0047] Example 2

[0048] Dissolve tetraethyl orthosilicate, aluminum sol, piperazine, 2-phenylacetamide, sodium hydroxide in water, stir to obtain a mixed solution, the molar ratio of each component in the mixed solution is SiO2:0.015Al2O3:0.2OSDA:0.1R:0.3NaOH:30H2O; load the mixed solution into a pressure steel kettle with a polytetrafluoroethylene liner, crystallize at 150°C for 3 days. After crystallization, cool to room temperature naturally, filter, wash, dry at 100°C for 8h, and finally calcine at 550°C in air for 5h to remove the template agent used, to obtain a molecular sieve.

[0049] The molecular sieve prepared in this example is MCM-22 molecular sieve, and the test results of the specific surface area and external specific surface area are shown in Table 1.

[0050] Example 3

[0051] The preparation method of the molecular sieve refers to Example 1, except that the molar ratio of each component in the mixed solution is SiO2:0.015Al2O3:0.2OSDA:0.4R:0.25NaOH:55H2O.

[0052] The molecular sieve prepared in this example is MCM-22 molecular sieve, and the test results of the specific surface area and external specific surface area are shown in Table 1.

[0053] Example 4

[0054] The preparation method of the molecular sieve refers to Example 1, except that 2-phenylacetamide is replaced by 4-acetylaminoethylpiperidine.

[0055] The molecular sieve prepared in this example is MCM-22 molecular sieve, and the test results of the specific surface area and external specific surface area are shown in Table 1.

[0056] Example 5

[0057] The preparation method of the molecular sieve refers to Example 1, except that 2-phenylacetamide is replaced by 1-methylpiperidine-4-carboxamide.

[0058] The molecular sieve prepared in this example is MCM-22 molecular sieve, and the test results of the specific surface area and external specific surface area are shown in Table 1.

[0059] Comparative Example 1

[0060] The preparation method of the molecular sieve refers to Example 1, except that 2-phenylacetamide is not added.

[0061] The molecular sieve prepared in this example is MCM-22 molecular sieve, and the test results of the specific surface area and external specific surface area are shown in Table 1.

[0062] Comparative Example 2

[0063] The molecular sieve was prepared according to the method of Example 1, except that 2- phenylacetamide was replaced by acrylamide.

[0064] The molecular sieve prepared in this comparative example was MCM-22 molecular sieve, and the test results of the specific surface area and external specific surface area are shown in Table 1.

[0065] Comparative Example 3

[0066] The molecular sieve was prepared according to the method of Example 1, except that no hexamethyleneimine was added.

[0067] The product prepared in this comparative example was amorphous.

[0068] Table 1

[0069]

[0070] It should be noted that the above-described examples are merely intended to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified within the scope of the claims of the present application, and the present application can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it does not mean that the present application is limited to the specific examples disclosed therein, but rather, the present application can be extended to all other methods and applications having the same function.

Claims

1. A high surface area MCM-22 molecular sieve characterized by, The MCM-22 molecular sieve has a specific surface area > 500 m 2 g -1 , an external specific surface area > 150 m 2 g -1 ; Preferably, The MCM-22 molecular sieve has a specific surface area of 520-600 m 2 g -1 ; and / or the MCM-22 molecular sieve has an external surface area of 160 to 200 m 2 g -1 .

2. A process for the preparation of a high surface area MCM-22 molecular sieve, characterized by, comprising: obtaining a mixed solution comprising a silicon source, an aluminum source, an alkali source, a solvent, an organic template agent and an additive, subjecting the mixed solution to a crystallization treatment, and calcining the crystallization product to obtain the high specific surface area MCM-22 molecular sieve; the additive is selected from a compound containing a six-membered ring structure and an amide group, the six-membered ring structure comprising a piperidyl group or a phenyl group; Preferably, the additive comprises at least one of piperidine-4-carboxamide, 1-methylpiperidine-4-carboxamide, 1-ethylpiperidine-4-carboxamide, 4-acetylamino piperidine, 4-acetylaminoethyl piperidine, 4-acetylamino-2, 2, 6, 6-tetramethyl-1-piperidinooxy, 2-phenylacetamide, 4-amino-N-methylbenzamide, p-aminobenzamide.

3. The preparation method according to claim 2, characterized in that, the silicon source comprises at least one of silica sol, tetraethyl orthosilicate, white carbon black, water glass; and / or, the aluminum source comprises at least one of aluminum sol, pseudo-boehmite, aluminum hydroxide, aluminum isopropoxide, aluminum sec-butoxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum oxide; and / or, the alkali source comprises at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, ammonia; and / or, the solvent comprises at least one of water, methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, diethylene glycol, glycerol, diglycerol; and / or, the organic template agent comprises at least one of hexamethyleneimine, piperidine, piperazine, homopiperazine, cyclohexylamine, diethylcyclohexylamine, dicyclohexylamine, ethanolamine.

4. The production method according to claim 2 or 3, characterized by, The silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, the alkali source is calculated as OH - The organic template is calculated as OSDA, the additive is calculated as R, and the solvent is calculated as I. The molar ratio of each raw material is as follows: SiO2 / Al2O3=20-100, OH - / SiO2=0.01-1, OSDA / SiO2=0.01-0.8, R / SiO2=0.05-0.8, and I / SiO2=3-300. Preferably, SiO2 / Al2O3=35-80; and / or, OH - / SiO2= 0.1-0.4; and / or, OSDA / SiO2=0.15-0.3; and / or, R / SiO2=0.1-0.5; and / or, I / SiO2=20-60.

5. The method of any one of claims 2-4, wherein, The temperature of the crystallization treatment is 100-200°C, preferably 140-180°C; the time of the crystallization treatment is 2-200h, preferably 24-144h, more preferably 60-120h.

6. The method of any one of claims 2-5, wherein, The temperature of the calcination is 400-700°C, preferably 500-600°C; the time of the calcination is 0.5-8h, preferably 4-6h; and / or, the calcination is performed in air.

7. The method of any one of claims 2-6, wherein, The crystallization product is cooled, filtered, washed, dried, and then calcined.

8. The method of any one of claims 2-7, wherein, The temperature of the drying is 50-150°C, preferably 80-120°C.

9. A high specific surface area MCM-22 molecular sieve prepared by the method of any one of claims 2-8.

10. Use of the high specific surface area MCM-22 molecular sieve of claim 1 or 9 in the field of catalysts.

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