Preparation method and application of hydrophobic modified molecular sieve

Abstract

The invention belongs to the technical field of molecular sieves, and particularly relates to a preparation method and application of a hydrophobic modified molecular sieve. The preparation method of the hydrophobic modified molecular sieve comprises the following steps: (1) activating a molecular sieve to obtain a pre-activated molecular sieve; and (2) mixing the pre-activated molecular sieve, a silane coupling agent and a solvent for reaction to obtain the hydrophobic modified molecular sieve. The hydrophobic modified molecular sieve has the beneficial effects that the pore channel structure of the hydrophobic modified molecular sieve and the pore channel structure of the molecular sieve before modification are not greatly changed, the good pore channel property of the molecular sieve is maintained, and the moisture interference resistance of the molecular sieve during carbon dioxide adsorption is improved. The molecular sieve hydrophobic modification method is simple and convenient to operate, low in cost and suitable for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieves, and in particular relates to a preparation method of a hydrophobically modified molecular sieve and an application thereof. Background Art

[0002] With the development of industrialization, carbon dioxide emissions from large industrial facilities such as coal-fired power plants, cement plants and steel mills have increasingly become one of the important sources of environmental pollution. Therefore, finding an effective method to reduce carbon dioxide emissions is of great significance for environmental protection. Traditional methods for reducing carbon dioxide emissions mainly include chemical absorption and physical adsorption, but these methods have problems such as low adsorption efficiency and high energy consumption.

[0003] Molecular sieves are excellent adsorbents with selective adsorption capabilities for molecules of different shapes, diameters, polarities, and unsaturation. In the adsorption of carbon dioxide, water vapor is the main interfering factor in carbon dioxide adsorption, but molecular sieves have a strong adsorption capacity for polar molecules (such as water molecules), so they need to be structurally modified. Therefore, achieving hydrophobic modification of zeolite molecular sieves is a technical problem that needs to be solved urgently by technicians in the relevant technical field. Summary of the invention

[0004] The present application provides a preparation method of a hydrophobically modified molecular sieve and its application, aiming to solve the problem that the existing molecular sieve has a low ability to adsorb carbon dioxide due to water vapor interference.

[0005] The first aspect of the present application provides a method for preparing a hydrophobically modified molecular sieve, comprising the following steps:

[0006] (1) activating the molecular sieve to obtain a pre-activated molecular sieve;

[0007] (2) The preactivated molecular sieve, the silane coupling agent and the solvent are mixed and reacted to obtain a hydrophobically modified molecular sieve.

[0008] The hydrophobic modified molecular sieve described in the present application has no significant change in the pore structure of the molecular sieve before modification, which maintains the good pore properties of the molecular sieve and improves the ability of the molecular sieve to resist water vapor interference during carbon dioxide adsorption. The hydrophobic modification method of the molecular sieve of the present application is simple to operate, low in cost, and suitable for large-scale production. The hydrophobic modified molecular sieve described in the present application has a wide range of applications, and is suitable for the application of carbon dioxide adsorption in multiple scenarios such as coal-fired power plants, cement plants and steel mills, and has broad application prospects and practical value.

[0009] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the molecular sieve includes one or more of an X-type molecular sieve, a Y-type molecular sieve and an A-type molecular sieve.

[0010] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the activation treatment includes activating the molecular sieve using nitrogen purge; preferably, the nitrogen purge temperature is 240-300° C., and the purge time is 1-2 h.

[0011] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the silane coupling agent includes a halogen-containing silane coupling agent and / or an amino-containing silane coupling agent.

[0012] According to some embodiments of the preparation method of the hydrophobically modified molecular sieve described in the present application, the halogen-containing silane coupling agent includes one or more of trimethoxy(pentafluorophenyl)silane, dimethylchlorosilane, n-butyltrichlorosilane, (2-bromoethoxy)tert-butyldimethylsilane, propyltrichlorosilane, octylmethyldichlorosilane, chloromethyl(dichloro)methylsilane, (3-cyanopropyl)trichlorosilane, isopropylchlorosilane, trimethyliodosilane, chloromethoxydimethylsilane, n-dodecyldimethylchlorosilane and diisopropyldichlorosilane.

[0013] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the amino-containing silane coupling agent includes 3-aminopropyltrimethoxysilane and / or 3-aminopropyldimethylmethoxysilane.

[0014] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the solvent includes one or more of methanol, ethanol, acetonitrile, tetrahydrofuran, acetone, dichloromethane, chloroform, dichloroethane, toluene, xylene, chlorobenzene, dichlorobenzene and dimethyl sulfoxide.

[0015] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the mass ratio of the molecular sieve to the silane coupling agent is 1:(0.4-0.8); the mass ratio of the molecular sieve to the solvent is 1:(3-6).

[0016] According to some embodiments of the method for preparing the hydrophobically modified molecular sieve described in the present application, the reaction temperature is 100-150° C., and the reaction time is 6-8 hours.

[0017] The second aspect of the present application provides a hydrophobically modified molecular sieve, which is prepared by the preparation method described in the first aspect of the present application.

[0018] According to some embodiments of the hydrophobically modified molecular sieve described in the present application, the contact angle between the hydrophobically modified molecular sieve and water is 50-95 degrees, and the selective adsorption coefficient of the hydrophobically modified molecular sieve for CO2 / H2O is 7-34.

[0019] Application of the hydrophobically modified molecular sieve obtained by the preparation method described in the first aspect of the present application or the hydrophobically modified molecular sieve described in the second aspect of the present application in adsorbing carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1a This is an optical image of the contact angle between the pressed tablet of the 13X molecular sieve raw powder and water described in Example 1 of the present application;

[0021] Figure 1b This is an optical image of the contact angle between the hydrophobically modified molecular sieve tablet and water prepared in Example 1 of the present application;

[0022] Figure 1c This is an optical image of the contact angle between the hydrophobically modified molecular sieve tablet and water prepared in Comparative Example 1 of the present application;

[0023] Figure 1d This is an optical image of the contact angle between the hydrophobically modified molecular sieve tablet and water prepared in Comparative Example 2 of the present application;

[0024] Figure 2a This is an optical image of the 13X molecular sieve raw powder particles in contact with water droplets as described in Example 1 of the present application;

[0025] Figure 2b This is an optical image of the hydrophobically modified molecular sieve particles prepared in Example 1 of the present application in contact with water droplets;

[0026] Figure 3 This is an analysis chart of the adsorption of CO2 gas by the hydrophobically modified molecular sieve prepared in Example 1 of the present application;

[0027] Figure 4 This is a diagram showing the effect of the hydrophobic modified molecular sieve prepared in Example 1 of the present application cyclically absorbing CO2 gas. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0029] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] The present invention provides a method for preparing a hydrophobically modified molecular sieve, comprising the following steps:

[0031] (1) activating the molecular sieve to obtain a pre-activated molecular sieve;

[0032] (2) The preactivated molecular sieve, the silane coupling agent and the solvent are mixed and reacted to obtain a hydrophobically modified molecular sieve.

[0033] The hydrophobically modified molecular sieve has uniform pore size, high adsorption capacity and selectivity for CO2 molecules, is resistant to high temperatures, has stable performance under low humidity, and is easy to regenerate and reuse.

[0034] The hydrophobic modified molecular sieve described in the present application has no significant change in the pore structure of the molecular sieve before modification, which maintains the good pore properties of the molecular sieve and improves the ability of the molecular sieve to resist water vapor interference during carbon dioxide adsorption. The hydrophobic modification method of the molecular sieve of the present application is simple to operate, low in cost, and suitable for large-scale production. The hydrophobic modified molecular sieve described in the present application has a wide range of applications, and is suitable for the application of carbon dioxide adsorption in multiple scenarios such as coal-fired power plants, cement plants and steel mills, and has broad application prospects and practical value.

[0035] In some embodiments of the present application, the molecular sieve includes one or more of X-type molecular sieve, Y-type molecular sieve and A-type molecular sieve;

[0036] In some embodiments of the present application, the X-type molecular sieve is a FAU structure with a silicon-aluminum ratio of 1 to 1.5, has excellent ion exchange performance and a large pore size, and is composed of silicon oxygen and aluminum oxygen tetrahedrons. The Y-type molecular sieve is a microporous crystalline material with high crystallinity and stability, composed of silicon oxygen aluminum oxygen tetrahedrons, polycyclic rings and β cages, octahedral zeolite cages, etc., including NaY and its modified products such as NH4Y, HY, USY, RY, etc. The A-type molecular sieve is a cubic lattice microporous structure with high adsorption and selective adsorption. It is divided into 3A, 4A, and 5A types, and the pore size increases successively.

[0037] In some embodiments of the present application, the activation treatment includes purging the molecular sieve with nitrogen for activation; preferably, the temperature of the nitrogen purge is 240-300°C, such as 240°C, 260°C, 280°C, 300°C, etc., and the purge time is 1-2h. Purging with nitrogen within this temperature range can more effectively remove physically adsorbed water and chemically bound water on the microporous surface inside the molecular sieve, as well as other volatile impurities that may exist. Removing these impurities helps to couple chlorosilanes with the surface of the molecular sieve. It is enough to optimize the pore structure inside the molecular sieve, making it more open and unobstructed. This helps to increase the specific surface area and pore volume of the molecular sieve and improve its adsorption capacity for CO2 molecules.

[0038] In some embodiments of the present application, the silane coupling agent includes a halogen-containing silane coupling agent and / or an amino-containing silane coupling agent.

[0039] Halogen groups and amino groups have special chemical properties and can form chemical bonds with the silanol groups of molecular sieves, thereby enhancing the bonding between inorganic and organic materials. The two types of silane coupling agents also have unique physical and chemical properties that can promote the modification of molecular sieve silanization, such as reducing viscosity, improving fluidity, having good wettability and dispersibility, and improving the dispersion of molecular sieves in organic solvents, thereby helping to improve the preparation efficiency and product quality of silane and molecular sieve composite materials.

[0040] In some embodiments of the present application, the halogen-containing silane coupling agent includes one or more of trimethoxy(pentafluorophenyl)silane, dimethylchlorosilane, n-butyltrichlorosilane, (2-bromoethoxy)tert-butyldimethylsilane, propyltrichlorosilane, octylmethyldichlorosilane, chloromethyl(dichloro)methylsilane, (3-cyanopropyl)trichlorosilane, isopropylchlorosilane, trimethyliodosilane, chloromethoxydimethylsilane, n-dodecyldimethylchlorosilane and diisopropyldichlorosilane.

[0041] In some embodiments of the present application, the amino-containing silane coupling agent includes 3-aminopropyltrimethoxysilane and / or 3-aminopropyldimethylmethoxysilane.

[0042] In some embodiments of the present application, the solvent includes one or more of methanol, ethanol, acetonitrile, tetrahydrofuran, acetone, dichloromethane, chloroform, dichloroethane, toluene, xylene, chlorobenzene, dichlorobenzene and dimethyl sulfoxide.

[0043] In some embodiments of the present application, the mass ratio of the molecular sieve to the silane coupling agent is 1:(0.4-0.8). At this ratio, the molecular sieve and the silane coupling agent can work together more effectively, achieving a better hydrophobic effect on water molecules, while ensuring the integrity of the molecular sieve pores, and minimizing the effect of the molecular sieve introduced with the silane agent on the adsorption of CO2 molecules. At the same time, at this ratio, the waste of the silane agent is avoided.

[0044] In some embodiments of the present application, the mass ratio of the molecular sieve to the solvent is 1:(3-6).

[0045] In some embodiments of the present application, the reaction temperature is 100-150°C, such as 100°C, 110°C, 120°C, 130°C, 150°C, etc., and the reaction time is 6-8h. Within this temperature range, the activity of the halosilane reagent is moderate, which is conducive to the smooth progress of the reaction, can shorten the reaction time, and improve the reaction efficiency. Compared with higher reaction temperatures, at lower temperatures, some unnecessary side reactions will be suppressed, thereby ensuring the utilization rate of the halosilane reagent. The heating energy consumption required in the temperature range of 100 to 150°C is low, which is conducive to reducing production costs.

[0046] The embodiment of the present application also provides a hydrophobically modified molecular sieve, which is prepared by the preparation method described in the first aspect of the present application.

[0047] In some embodiments of the present application, the hydrophobically modified molecular sieve is obtained by a specific preparation method, which generally includes an activation treatment of the molecular sieve, the introduction of a silane coupling agent, and a subsequent hydrophobic modification step. These steps act together on the molecular sieve to change its surface properties, thereby having hydrophobic characteristics.

[0048] In some embodiments of the present application, the contact angle between the hydrophobically modified molecular sieve and water is 50-95 degrees, and the selective adsorption coefficient of the hydrophobically modified molecular sieve for CO2 / H2O is 7-34.

[0049] The embodiments of the present application also provide an application of the hydrophobically modified molecular sieve obtained by the preparation method described in the first aspect of the present application or the hydrophobically modified molecular sieve described in the second aspect of the present application in adsorbing carbon dioxide.

[0050] The technical solution of the present application is further described below in conjunction with specific embodiments and drawings.

[0051] Example 1

[0052] A method for preparing a hydrophobically modified molecular sieve comprises the following steps:

[0053] (1) 100 g of 13X molecular sieve powder was loaded into quartz (both ends were sealed with alumina short fiber loose cotton), and the molecular sieve powder was purged and activated with nitrogen at a purging temperature of 250° C. The pre-activated molecular sieve was obtained by purging at this temperature for 1 h;

[0054] (2) Dissolve the preactivated molecular sieve in 630 mL (500 g) of ethanol to obtain a molecular sieve dispersion, transfer the molecular sieve dispersion into a high-pressure reactor, add 60 g of trimethoxy (pentafluorophenyl) silane coupling agent into the high-pressure reactor, react at 110° C. for 6 h, stop the reaction, cool the reaction solution naturally, filter the reaction solution, wash the filtered solid with ethanol, and then dry it to obtain a hydrophobically modified molecular sieve.

[0055] Example 2

[0056] The preparation method of the hydrophobically modified molecular sieve described in Example 2 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 2, dimethyldichlorosilane coupling agent is used instead of trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0057] Example 3

[0058] The preparation method of the hydrophobically modified molecular sieve described in Example 3 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 3, n-butyltrichlorosilane coupling agent is used instead of trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0059] Example 4

[0060] The preparation method of the hydrophobically modified molecular sieve described in Example 4 is different from that of Example 1 only in that: during the preparation process of the hydrophobically modified molecular sieve described in Example 4, 3-aminopropyltrimethoxysilane coupling agent is used instead of the trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0061] Example 5

[0062] The preparation method of the hydrophobically modified molecular sieve described in Example 5 is different from that of Example 1 only in that: during the preparation process of the hydrophobically modified molecular sieve described in Example 5, (2-bromoethoxy) tert-butyldimethylsilane coupling agent is used instead of the trimethoxy (pentafluorophenyl) silane coupling agent described in Example 1.

[0063] Example 6

[0064] The preparation method of the hydrophobically modified molecular sieve described in Example 6 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 6, propyltrichlorosilane coupling agent is used instead of the trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0065] Example 7

[0066] The preparation method of the hydrophobically modified molecular sieve described in Example 7 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 7, octylmethyl dichlorosilane coupling agent is used instead of trimethoxy (pentafluorophenyl) silane coupling agent described in Example 1.

[0067] Example 8

[0068] The preparation method of the hydrophobically modified molecular sieve described in Example 8 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 8, chloromethyl (dichloro)methyl silane coupling agent is used instead of the trimethoxy (pentafluorophenyl) silane coupling agent described in Example 1.

[0069] Example 9

[0070] The preparation method of the hydrophobically modified molecular sieve described in Example 9 is different from that of Example 1 only in that: during the preparation process of the hydrophobically modified molecular sieve described in Example 9, (3-cyanopropyl)trichlorosilane coupling agent is used instead of the trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0071] Example 10

[0072] The preparation method of the hydrophobically modified molecular sieve described in Example 10 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 10, isopropyl chlorosilane coupling agent is used instead of trimethoxy (pentafluorophenyl) silane coupling agent described in Example 1.

[0073] Embodiment 11

[0074] The preparation method of the hydrophobically modified molecular sieve described in Example 11 is different from that in Example 1 only in that: during the preparation process of the hydrophobically modified molecular sieve described in Example 11, 3-aminopropyldimethylmethoxysilane coupling agent is used instead of the trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0075] Example 12

[0076] The preparation method of the hydrophobically modified molecular sieve described in Example 12 is different from that of Example 1 only in that: during the preparation process of the hydrophobically modified molecular sieve described in Example 12, trimethyl iodide silane coupling agent is used instead of the trimethoxy (pentafluorophenyl) silane coupling agent described in Example 1.

[0077] Embodiment 13

[0078] The preparation method of the hydrophobically modified molecular sieve described in Example 13 is different from that of Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 13, chloromethoxydimethylsilane coupling agent is used instead of trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0079] Embodiment 14

[0080] The preparation method of the hydrophobically modified molecular sieve described in Example 14 is different from that in Example 1 only in that during the preparation of the hydrophobically modified molecular sieve described in Example 14, n-dodecyldimethylchlorosilane coupling agent is used instead of trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0081] Embodiment 15

[0082] The preparation method of the hydrophobically modified molecular sieve described in Example 15 is different from that of Example 1 only in that: during the preparation process of the hydrophobically modified molecular sieve described in Example 15, diisopropyldichlorosilane coupling agent is used instead of the trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0083] Comparative Example 1

[0084] The preparation method of the hydrophobically modified molecular sieve described in Comparative Example 1 is different from that of Example 1 only in that: in the preparation process of the hydrophobically modified molecular sieve described in Comparative Example 1, the 13X molecular sieve raw powder is not activated, and the 13X molecular sieve raw powder is directly dispersed in ethanol and reacted with trimethoxy(pentafluorophenyl)silane coupling agent.

[0085] Comparative Example 2

[0086] The preparation method of the hydrophobically modified molecular sieve described in Comparative Example 2 is different from that in Example 1 only in that: the hydrophobically modified molecular sieve described in Comparative Example 2 uses γ-(2,3-epoxypropoxy)propyltrimethoxysilane in the preparation process instead of the trimethoxy(pentafluorophenyl)silane coupling agent described in Example 1.

[0087] Performance study of the hydrophobically modified molecular sieve obtained by the preparation method of the hydrophobically modified molecular sieve described in this application:

[0088] 1. Take equal amounts of 13X molecular sieve powder and the hydrophobically modified molecular sieve prepared by the methods of Example 1 and Comparative Examples 1-2 for tableting. The tableting pressure is 2t. The pure water contact angles of the molecular sieve powder tablets are measured (stable time is 1min, droplet size is 2μL). The contact angle optical image test results are shown in Figure 1. Figure 1a The unmodified 13X molecular sieve raw powder is pressed into tablets; Figure 1b The hydrophobically modified molecular sieve tablets obtained by the preparation method of Example 1; Figure 1cThe tablet is a hydrophobically modified molecular sieve prepared in Comparative Example 1 of the present application; Figure 1d Tablets of the hydrophobically modified molecular sieve prepared in Comparative Example 2 of the present application.

[0089] As can be seen from Figure 1: after the unmodified 13X molecular sieve tablets were stabilized for 1 minute, the water permeability of the tablets was relatively high, and the contact angle of the remaining droplets was 6.1 degrees, while the water permeability of the hydrophobically modified molecular sieve tablets obtained by the preparation method of Example 1 was relatively low, and the contact angle of the remaining droplets was 67.9 degrees. The results show that the hydrophobically modified molecular sieve described in the present application has a significant hydrophobic effect.

[0090] 2. The 13X molecular sieve raw powder and the hydrophobically modified molecular sieve prepared by the method of Example 1 were granulated by the same method, and the granulated molecular sieves were subjected to a water drop contact test. The test results of the water drop contact image are shown in FIG2 . Figure 2a This is an optical image of unmodified 13X molecular sieve particles in contact with water droplets. Figure 2b This is an optical image of the hydrophobically modified molecular sieve particles obtained by the preparation method of Example 1 in contact with water droplets.

[0091] As can be seen from Figure 2: after the unmodified 13X molecular sieve particles came into contact with water droplets, the water droplets and the unmodified molecular sieve merged, while the hydrophobically modified molecular sieve obtained by the preparation method of Example 1 showed an obvious separation interface with the water droplets, further illustrating that the hydrophobic effect of the modified molecular sieve obtained by the preparation method of the hydrophobically modified molecular sieve described in the present application meets the expected requirements.

[0092] 3. A 15% volume concentration of CO2 gas (the other mixed gas is nitrogen) was introduced into the hydrophobically modified molecular sieve prepared by the method of Example 1, and the adsorption amount of CO2 gas was investigated under the conditions of ambient temperature 40°C and relative humidity (RH) 15% by a penetration adsorption experiment. The results are as follows: Figure 3 shown.

[0093] from Figure 3 It can be seen that the hydrophobically modified molecular sieve prepared by the preparation method of Example 1 of the present application can reach the adsorption equilibrium of CO2 with a volume concentration of 15% in about 100 seconds at a relative humidity of 15%. Although there is the influence of water vapor, it does not affect the adsorption of CO2 by the hydrophobically modified molecular sieve. Under this condition, the hydrophobically modified molecular sieve exhibits a CO2 adsorption capacity of 0.068g / g and a H2O adsorption capacity of 0.007g / g, and the adsorption coefficient (CO2 / H2O) is selected to be 14; that is, the interference of water vapor will cause the adsorption kinetics of CO2 to change, and the saturated adsorption capacity will be reached in a short time. However, the adsorption peak of the 13X molecular sieve after hydrophobic modification is not affected.

[0094] According to the same test method as above, the contact angle and selective adsorption coefficient of the hydrophobic modified molecular sieves prepared in Examples 2-15 and Comparative Examples 1-2 with water were tested respectively. The results are shown in Table 1.

[0095] Table 1

[0096]

[0097] It can be seen from Table 1 that the halogenated silane coupling agents in most of the embodiments can significantly increase the contact angle of the molecular sieve, indicating that these silane coupling agents have successfully introduced hydrophobic groups. The contact angles of Comparative Example 1 (unpurged activated molecular sieve) and Comparative Example 2 (using γ-(2,3-epoxypropoxy)propyltrimethoxysilane) are relatively low, indicating that the purging activation treatment and the selection of the type of suitable silane coupling agent are crucial to the hydrophobic modification. Among them, the polychlorinated, brominated, and iodinated silane coupling agents in the embodiments (such as the silane coupling agents used in Examples 5, 8, 9, and 12) can significantly improve the hydrophobicity of the molecular sieve and the selective adsorption capacity of CO2, and have potential application value.

[0098] 4. After the hydrophobically modified molecular sieve prepared by the method for preparing the hydrophobically modified molecular sieve described in Example 1 of the present application was immersed in water for up to 6 hours, it was filtered and dried, and the above immersion, filtration and drying operations were repeated. After each immersion and drying, the adsorption capacity of CO2 gas was tested according to 3 (test of the adsorption capacity of CO2 gas by the hydrophobically modified molecular sieve described in the present application). The cycle test results are as follows: Figure 4 shown.

[0099] from Figure 4 It can be seen from the results that: through the cyclic adsorption experiment, after the hydrophobically modified molecular sieve described in the present application has been soaked in water ten times, the hydrophobically modified molecular sieve still exhibits excellent adsorption performance, and the CO2 adsorption performance can still be maintained at above 92%.

[0100] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrophobically modified molecular sieve, characterized in that: The following steps are involved: (1) activating the molecular sieve to obtain a pre-activated molecular sieve; (2) The preactivated molecular sieve, the silane coupling agent and the solvent are mixed and reacted to obtain a hydrophobically modified molecular sieve.

2. The method for preparing the hydrophobically modified molecular sieve according to claim 1, characterized in that: The molecular sieve includes one or more of X-type molecular sieve, Y-type molecular sieve and A-type molecular sieve; And / or, the activation treatment comprises purging the molecular sieve with nitrogen for activation; preferably, the nitrogen purging temperature is 240-300° C., and the purging time is 1-2 h.

3. The method for preparing the hydrophobically modified molecular sieve according to claim 1, characterized in that: The silane coupling agent includes a halogen-containing silane coupling agent and / or an amino-containing silane coupling agent.

4. The method for preparing the hydrophobically modified molecular sieve according to claim 3, characterized in that: The halogen-containing silane coupling agent includes one or more of trimethoxy (pentafluorophenyl) silane, dimethylchlorosilane, n-butyltrichlorosilane, (2-bromoethoxy) tert-butyldimethylsilane, propyltrichlorosilane, octylmethyldichlorosilane, chloromethyl (dichloro) methylsilane, (3-cyanopropyl) trichlorosilane, isopropylchlorosilane, trimethyliodosilane, chloromethoxydimethylsilane, n-dodecyldimethylchlorosilane and diisopropyldichlorosilane; And / or, the amino-containing silane coupling agent includes 3-aminopropyltrimethoxysilane and / or 3-aminopropyldimethylmethoxysilane.

5. The method for preparing the hydrophobically modified molecular sieve according to claim 1, characterized in that: The solvent includes one or more of methanol, ethanol, acetonitrile, tetrahydrofuran, acetone, dichloromethane, chloroform, dichloroethane, toluene, xylene, chlorobenzene, dichlorobenzene and dimethyl sulfoxide.

6. The method for preparing the hydrophobically modified molecular sieve according to claim 1, characterized in that: The mass ratio of the molecular sieve to the silane coupling agent is 1:(0.4-0.8); the mass ratio of the molecular sieve to the solvent is 1:(3-6).

7. The method for preparing the hydrophobically modified molecular sieve according to claim 1, characterized in that: The reaction temperature is 100-150° C., and the reaction time is 6-8 hours.

8. A hydrophobically modified molecular sieve, characterized in that: The hydrophobically modified molecular sieve is prepared by the preparation method according to any one of claims 1 to 6.

9. The hydrophobically modified molecular sieve according to claim 8, characterized in that: The contact angle between the hydrophobically modified molecular sieve and water is 50-95 degrees, and the selective adsorption coefficient of the hydrophobically modified molecular sieve to CO2 / H2O is 7-34.

10. Use of the hydrophobically modified molecular sieve obtained by the preparation method according to any one of claims 1 to 7 or the hydrophobically modified molecular sieve according to any one of claims 8 to 9 in adsorbing carbon dioxide.

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