Adsorption material for VOCs adsorption, preparation method and application thereof

Abstract

The present invention provides an adsorption material for VOCs adsorption, a preparation method and an application thereof, which specifically include: mixing a silicon source, an aluminum source, an organic template and water in an optimized ratio, stirring and mixing them at a specific temperature, and then pre-crystallizing, drying and calcining to obtain a high-efficiency adsorption material. The high-efficiency adsorption material provided by the present invention has a simple preparation route, good hydrothermal stability, a large specific surface area, and a high micropore content, and is suitable for the adsorption of volatile organic molecules including xylene and toluene. Especially under conditions of high environmental humidity, its adsorption performance is far superior to that of traditional molecular sieve adsorption materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic synthesis, and specifically relates to an adsorption material for VOCs adsorption, a preparation method and an application thereof. Background Art

[0002] The emission of volatile organic compounds (VOCs) has caused serious harm to the natural environment and human health. Adsorption is an effective method for controlling VOCs. The kinetic diameter of VOCs molecules is generally less than 1nm. When the pore size of the adsorbent matches the kinetic diameter of the VOCs molecules, the adsorbed organic molecules are not easy to escape. Currently, the commonly used VOCs adsorption materials mainly include activated carbon and zeolite molecular sieves. Activated carbon has a large specific surface area and good performance, but its thermal stability is poor, it is easy to burn, and it is difficult to desorb VOCs molecules, and it faces the problem of hazardous waste treatment. Zeolite molecular sieve is a porous material with rich microporous structure, large specific surface area and micropore volume, and excellent thermal stability and hydrothermal stability. It has been widely used in the field of VOCs adsorption.

[0003] CN108862311A reports a method for preparing a high-silicon ZSM-5 molecular sieve adsorption material, using alkyl ammonium as a template, mixing a silicon source, an alkali source and a ZSM-5 seed crystal for preparation, and introducing aluminum in the molecular sieve in the form of silicon source impurities, and the molecular sieve needs to be treated with hydrochloric acid, nitric acid and other acids in the later stage, and then ammonium exchange is performed to prepare a high-silicon H-ZSM-5 molecular sieve. It has a long crystallization time, low yield, complex preparation process and high cost.

[0004] CN106672995A reports a method for preparing a high-silicon Y molecular sieve adsorption material. First, low silicon-aluminum ratio NaY is subjected to ammonium exchange, high-temperature hydrothermal treatment, and then dealumination and silicon supplementation treatment is performed with ammonium fluorosilicate, and finally a high-silicon, high-crystallinity modified Y molecular sieve is obtained.

[0005] CN101757889B reports a BEA type binder-free hydrophobic high-silicon zeolite adsorbent and a preparation method thereof, wherein a sodium-type BEA zeolite is added with an amorphous silica-alumina binder rich in silica to obtain a granular material, which is then hydrothermally crystallized and then dealuminated with an inorganic acid and treated with high-temperature steam to obtain a hydrophobic high-silicon zeolite.

[0006] In summary, the efficient molecular sieve adsorption materials for VOCs are concentrated in the high-silicon ZSM-5, Y and Beta molecular sieve systems, but there are still many problems in the actual preparation process. Based on the good hydrothermal stability of zeolite molecular sieve materials, this patent intends to develop a simple preparation path for efficient VOCs adsorption materials, through the preparation of silicon-alumina amorphous materials with high surface area, high micropore content and large micropore size, to achieve efficient adsorption of VOCs molecules including xylene and toluene. Summary of the invention

[0007] The present invention provides a highly efficient adsorption material for VOCs adsorption and a preparation method thereof. By precisely controlling the material composition and crystallization treatment conditions, a VOCs adsorption material with a large specific surface area and a high micropore content can be prepared. The adsorption material is suitable for adsorption of volatile organic molecules including xylene and toluene, and its adsorption performance is far superior to that of traditional molecular sieve adsorption materials, especially under conditions of high environmental humidity. The preparation route is simple and easy to operate, and has a strong application prospect.

[0008] According to one aspect of the present application, a method for preparing an adsorbent material is provided for VOCs adsorption;

[0009] At least the following steps are included:

[0010] The silicon source, the aluminum source, the organic template and water are mixed, pre-crystallized, dried and calcined to obtain the adsorption material.

[0011] The aluminum source is selected from at least one of aluminum sulfate, sodium metaaluminate or aluminum isopropoxide;

[0012] The silicon source is selected from at least one of white carbon black, silica sol, silica gel or ethyl orthosilicate;

[0013] The organic template is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, N,N,N-trimethyladamantanium, tetrabutylammonium hydroxide and tetrahexylammonium hydroxide.

[0014] The molar ratio of the silicon source to the aluminum source is 50 to ∞;

[0015] The molar ratio of the organic template to the silicon source is 0.05 to 0.45;

[0016] The molar ratio of water to silicon source is 8 to 34;

[0017] The molar amount of the silicon source is based on the molar amount of silicon dioxide;

[0018] The molar amount of the aluminum source is based on the molar amount of aluminum oxide.

[0019] The pre-crystallization process is hydrothermal crystallization at a temperature of 60 to 90° C. for 0.5 to 18 hours.

[0020] The drying method is vacuum freeze drying or oven drying;

[0021] The drying temperature is -90 to 120°C;

[0022] The drying time is 3 to 12 hours.

[0023] The calcination process is to increase the temperature to 500-600° C. at a heating rate of 2-5° C. / min and maintain the temperature for 4-8 hours.

[0024] The mixing includes stirring;

[0025] The stirring temperature is 20 to 40°C;

[0026] The stirring time is 3 to 24 hours.

[0027] According to another aspect of the present application, an adsorption material is provided, which is prepared by the above-mentioned preparation method.

[0028] According to another aspect of the present application, a method for adsorbing volatile organic compounds is provided, wherein the volatile organic compounds are adsorbed by the above-mentioned adsorption material;

[0029] The volatile organic compound is selected from at least one of xylene or toluene;

[0030] The ambient humidity is 40% to 90%.

[0031] The amorphous adsorption material obtained by the present invention has a large specific surface area and a high micropore content, and can effectively separate water molecules and VOCs. In addition, the VOCs adsorption material has a low water absorption rate, which can reduce the competitive adsorption between water vapor and VOCs and improve the removal rate of VOCs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 X-ray diffraction (XRD) patterns of samples prepared in Examples 1 to 4;

[0033] Figure 2a a, b, c, and d are scanning electron microscope (SEM) images of the samples prepared in Examples 1 to 4, respectively. DETAILED DESCRIPTION

[0034] The present invention is further described below with examples, but the examples are not intended to limit the present invention.

[0035] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0036] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased through commercial channels.

[0037] The specific information of various substances used in the examples are as follows:

[0038] Tetraethyl orthosilicate (TEOS) (Kermel, >98wt%);

[0039] Silica sol (Qingdao Ocean Chemical Co., Ltd., 30wt% SiO2);

[0040] Silica gel (Aladdin, 95wt% SiO2);

[0041] White carbon (McLean, 95wt% SiO2);

[0042] Aluminum isopropoxide (Merrel, 98 wt%);

[0043] Al2(SO4)3·18H2O (Kermiou, 99wt%);

[0044] NaAlO2 (McLean, 80wt%);

[0045] TMAOH (Merrel, 25 wt%);

[0046] TEAOH (Merrill, 25wt%);

[0047] TPAOH (Merrill, 25 wt%);

[0048] TBAOH (Merrill, 40 wt%);

[0049] Deionized water (homemade).

[0050] Comparative Example 1

[0051] 0.21g NaOH, 20.82g TEOs, and 30.96g H2O were stirred at 25°C for 24h, then transferred to an oven and dried at 120°C. After drying, the mixture was heated to 500°C at a rate of 2°C / min and calcined for 5h to obtain the final product. The obtained sample was subjected to a N2 physical adsorption test, and the specific surface area of ​​the sample was 126m 2 / g, micropore volume is 0.015cm 3 / g. When the concentration of m-xylene is 500mg / m 3 , volume space velocity is 10000h -1 Under the conditions of adsorption temperature of 30℃ and relative humidity of 60%, the saturated adsorption capacity is 2.51mg / g.

[0052] Example 1

[0053] 11.38g TBAOH, 10.37g TEOs, and 8.26g H2O were stirred at 30°C for 3h, and then transferred to a vacuum freeze dryer and dried at -90°C. After drying, the temperature was raised to 550°C at a rate of 3°C / min for 8h to obtain the final product. The XRD pattern of the obtained product is shown in Figure 1 As shown in Figure 2, the product is an irregular block structure. The obtained sample was subjected to N2 physical adsorption test, and the specific surface area of ​​the sample was 802m 2 / g, micropore volume is 0.326cm3 / g. When the concentration of m-xylene is 1000mg / m 3 , volume space velocity is 12000h -1 Under the conditions of adsorption temperature of 40℃ and relative humidity of 80%, the saturated adsorption capacity is 70mg / g.

[0054] Example 2

[0055] 14.64g TPAOH, 10.00g silica sol, 0.34g Al2(SO4)3·18H2O, 4.50g H2O were stirred at 40℃ for 5h, transferred to an oven, and dried at 80℃. After drying, the mixture was calcined at 600℃ at a rate of 5℃ / min for 6h to obtain the final product. The XRD spectrum of the obtained product is shown in Figure 1 As shown in Figure 2, the product is an irregular block structure. The obtained sample was subjected to N2 physical adsorption test, and the specific surface area of ​​the sample was 729m 2 / g, micropore volume is 0.231cm 3 / g. When the toluene concentration is 2000mg / m 3 , volume space velocity is 10000h -1 Under the conditions of adsorption temperature of 40℃ and relative humidity of 50%, the saturated adsorption capacity is 46mg / g.

[0056] Example 3

[0057] 19.83g TEAOH, 10.63g silica gel, 0.18g aluminum isopropoxide, and 10.25g H2O were stirred at 35°C for 8h, and then hydrothermally crystallized at 70°C for 6h. After the pre-crystallization, the product was transferred to an oven and dried at 40°C. After drying, the product was calcined at 550°C at a rate of 3°C / min for 5h to obtain the final product. The XRD spectrum of the obtained product is shown in Figure 1 As shown in Figure 2, the product is an irregular block structure. The obtained sample was subjected to N2 physical adsorption test, and the specific surface area of ​​the sample was 457m 2 / g, micropore volume is 0.136cm 3 / g. When the toluene concentration is 1000mg / m 3 , volume space velocity is 15000h -1 Under the conditions of adsorption temperature of 35°C and relative humidity of 40%, the saturated adsorption capacity is 28 mg / g.

[0058] Example 4

[0059] 15.76g TMAOH, 12.34g white carbon black, 0.20g NaAlO2, 18.63g H2O were stirred at 25℃ for 20h, and then hydrothermally crystallized at 90℃ for 3h. After the pre-crystallization, the product was transferred to an oven and dried at 100℃. After drying, the product was calcined at 550℃ at a rate of 2℃ / min for 7h to obtain the final product. The XRD spectrum of the obtained product is shown in Figure 1 As shown in Figure 2, the product is an irregular block structure. The obtained sample was subjected to N2 physical adsorption test, and the specific surface area of ​​the sample was 370m 2 / g, micropore volume is 0.085cm 3 / g. When the concentration of p-xylene is 500mg / m 3 , volume space velocity is 10000h -1 Under the conditions of adsorption temperature of 30℃ and relative humidity of 40%, the saturated adsorption capacity is 23mg / g.

[0060] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing an adsorbent material, characterized in that: Used for VOCs adsorption; At least the following steps are included: Mixing a silicon source, an aluminum source, an organic template and water, pre-crystallizing, drying and calcining to obtain the adsorption material; The aluminum source is selected from at least one of aluminum sulfate, sodium metaaluminate or aluminum isopropoxide; The silicon source is selected from at least one of white carbon black, silica sol, silica gel or ethyl orthosilicate; The organic template is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, N,N,N-trimethyladamantanium, tetrabutylammonium hydroxide or tetrahexylammonium hydroxide; The pre-crystallization process is hydrothermal crystallization at a temperature of 60-90° C. for 0.5-18 h; The calcination process is to increase the temperature to 500-600°C at a heating rate of 2-5°C / min and maintain for 4-8h; The mixing includes stirring; The stirring temperature is 20-40°C; The stirring time is 3 to 24 hours; The molar ratio of the silicon source to the aluminum source is 50 to ∞; The molar ratio of the organic template to the silicon source is 0.05-0.45; The molar ratio of water to silicon source is 8 to 34; The molar amount of the silicon source is based on the molar amount of silicon dioxide; The molar amount of the aluminum source is based on the molar amount of aluminum oxide.

2. The preparation method according to claim 1, characterized in that: The drying method is vacuum freeze drying or oven drying; The drying temperature is -90~120°C; The drying time is 3 to 12 hours.

3. An adsorption material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 2.

4. A method for adsorbing volatile organic compounds, characterized in that: Adsorbing volatile organic matter by the adsorption material according to claim 3; The volatile organic compound is selected from at least one of xylene or toluene; The ambient humidity is 40%~90%.

Images