Hydrogen fluoride adsorbent as well as preparation method and application thereof

Abstract

The invention relates to the field of adsorbents, and discloses a hydrogen fluoride adsorbent as well as a preparation method and application thereof. The hydrogen fluoride adsorbent provided by the invention is an aluminum oxide matrix adsorbent, the amount of larger pores with the pore diameter larger than 3 nm of the adsorbent accounts for 85-95% of the total amount of the pores of the adsorbent, the amount of medium pores with the pore diameter of 1.5-3 nm accounts for 5-15% of the total amount of the pores of the adsorbent, and the amount of smaller pores with the pore diameter smaller than 1.5 nm accounts for 0-5% of the total amount of the pores of the adsorbent. The specific surface area of the aluminum oxide is 210-290 m < 2 > / g, and the aluminum oxide is pure-phase gamma-Al2O3. The adsorbent has a specific specific surface area, a specific pore ratio and a specific crystal phase, and can efficiently capture hydrogen fluoride molecules, so that the adsorbent has high hydrogen fluoride adsorption capacity and effectively meets the requirements of subsequent use working conditions.

Description

Technical Field

[0001] The present invention relates to the field of adsorbents, and specifically relates to a hydrogen fluoride adsorbent, a preparation method thereof, and an application thereof. Background Art

[0002] Due to their unique physical, chemical, and physiological activities, fluorine-containing chemicals are widely used in aspects such as rockets, aerospace, atomic energy, metallurgy, electronics, machinery, light industry, textiles, construction, medicine, and agriculture. Hydrogen fluoride (HF), as a basic fluorochemical product, is indispensable in the production of refrigerants, fluororesins, fluorinated salts, fluororubbers, fluorine-containing intermediates, and related fine chemicals. Most of the production of fluorine-containing chemicals is obtained by reacting HF with other materials. In order to achieve better fluorination effects, HF is generally used in excess. Due to the strong corrosiveness of hydrogen fluoride, its presence will affect product quality, safe production, and the resource utilization of tail gas. For example, a large amount of by-product hydrogen chloride containing hydrogen fluoride is generated during the preparation of chlorofluorocarbons, which severely restricts the efficient conversion and upgrading of the obtained hydrogen chloride downstream. Therefore, the treatment of HF gas is a key issue faced by the fluorochemical industry. Common hydrogen fluoride adsorption methods are divided into two categories: wet methods and dry methods. The waste liquid or sludge obtained by the former has high corrosiveness and is difficult to treat. To ensure the safe discharge or high-value application of fluorine-containing tail gas, a large amount of research has been carried out on the dry removal of hydrogen fluoride.

[0003] US4128626A and US3976447A respectively use a calcium chloride bed layer and a calcium fluoride bed layer to treat HF-containing gas (including hydrogen chloride gas containing HF). The HF concentration at the outlet of the adsorption bed is effectively reduced. However, based on the experimental experience in this field, it is known that both types of adsorbents must have a developed pore structure to exhibit excellent adsorption activity, and conventional and easily available calcium chloride and calcium fluoride particles cannot serve properly.

[0004] CN100522341C provides a hydrogen fluoride adsorbent, which is obtained by mixing, pulverizing, molding, and drying alkali metal fluorides, alkaline earth metal fluorides, and alkali metal hydrogen fluorides alone or in any proportion. The active component of this adsorbent reacts with HF to form hydrogen fluoride, and it is suitable for removing fluorine from the tail gas in the production of products such as chlorofluorocarbons, hydrofluorocarbons, and sulfuryl fluoride.

[0005] CN113877535A mixes polyacrylonitrile with one or more of alkali metal fluorides, alkaline earth metal fluorides, and alkali metal hydrogen fluorides to prepare a porous carbon sphere alkali metal hybrid composite adsorbent for removing fluorine from the acid gas generated during impurity removal in the production of lithium hexafluorophosphate products. The above two types of adsorbents have remarkable performance in removing HF, but the raw material fluorinated metal increases the cost of the adsorbent and is not suitable for use in large-scale production conditions. Alumina is the most commonly used hydrogen fluoride adsorbent in the aluminum electrolysis industry, but it is mostly used in powder form in fluidized beds, and the solid-gas separation in corrosive gases is extremely difficult, which limits the application of the fluidized bed adsorption method.

[0006] Based on the current situation, it is still an important task that needs to be completed urgently to develop a dry fixed-bed adsorbent with simple preparation, low cost, large adsorption capacity and selective removal of hydrogen fluoride. Summary of the Invention

[0007] The purpose of the present invention is to provide a hydrogen fluoride adsorbent, its preparation method and application. The inventors of the present invention have found through a large number of studies and experiments that a pure-phase γ-Al 2 O 3 adsorbent can be prepared by this method, and the adsorbent has a specific specific surface area, average pore diameter, crystal phase and crystal grain morphology, so that it has a high hydrogen fluoride adsorption capacity and can effectively meet the requirements of subsequent use conditions.

[0008] To achieve the above object, the present invention provides a hydrogen fluoride adsorbent, wherein the hydrogen fluoride adsorbent is an alumina-based adsorbent, and the amount of larger pores with a pore diameter greater than 3 nm in the adsorbent accounts for 85-95% of the total pore volume of the adsorbent, the amount of medium pores with a pore diameter of 1.5-3 nm accounts for 5-15% of the total pore volume of the adsorbent, and the amount of smaller pores with a pore diameter less than 1.5 nm accounts for 0-5% of the total pore volume of the adsorbent. Its specific surface area is 210-290 m 2 / g, wherein the alumina is pure-phase γ-Al 2 O 3 .

[0009] Preferably, the specific surface area of the hydrogen fluoride adsorbent is 210-290 m 2 / g, preferably 220-255 m 2 / g, more preferably 230-250 m 2 / g.

[0010] Preferably, the average pore diameter of the hydrogen fluoride adsorbent is 6-9 nm, more preferably 6.7-8.5 nm, and further preferably 7.9-8.3 nm.

[0011] Preferably, the hydrogen fluoride adsorbent is spherical and / or bar-shaped.

[0012] Preferably, the particle size of the spherical shape is 1-2 mm, more preferably 1.3-1.7 mm.

[0013] Preferably, the length of the bar-shaped is 1-2 mm, and the cross-sectional area is 0.19-6.25 mm 2 ; more preferably, the length of the bar-shaped is 1.3-1.7 mm, and the cross-sectional area is 1.25-5 mm 2 .

[0014] Preferably, the pure-phase γ-Al of the hydrogen fluoride adsorbent2 O 3 The crystal grains are lamellar, and there is a loose and porous structure between the lamellae.

[0015] In a second aspect of the present invention, a method for preparing a hydrogen fluoride adsorbent is characterized in that the method comprises the following steps:

[0016] 1) In the presence of a solvent, an aluminum source, a forming aid, and a peptizing agent are brought into contact to obtain a contact product;

[0017] 2) The contact product is successively dried and calcined,

[0018] wherein the calcination includes a first-stage calcination, a second-stage calcination, and a third-stage calcination;

[0019] The conditions for the first-stage calcination include: heating to 250°C - 300°C at a heating rate of 15°C - 20°C / min;

[0020] The conditions for the second-stage calcination include: heating to 400°C - 450°C at a heating rate of 3°C - 10°C / min, and maintaining for 15 - 60 min after heating;

[0021] The conditions for the third-stage calcination include: heating to 500°C - 650°C at a heating rate of 1°C - 5°C / min, and maintaining for 60 - 300 min after heating.

[0022] Preferably, the aluminum source is selected from one or more of pseudo-boehmite, boehmite, and aluminum hydroxide.

[0023] Preferably, the forming aid is selected from one or more of a lubricant, a plasticizer, and a pore-forming agent.

[0024] Preferably, the lubricant is selected from one or more of ethylene glycol, propylene glycol, and glycerol.

[0025] Preferably, the plasticizer is selected from hydroxyethyl cellulose and / or polyethylene glycol.

[0026] Preferably, the pore-forming agent is selected from one or more of sesbania powder, starch, and sawdust.

[0027] More preferably, the forming aid is selected from sesbania powder and / or starch.

[0028] Preferably, the peptizing agent is selected from one or more of acetic acid, nitric acid, citric acid, formic acid, and phosphoric acid solution; more preferably nitric acid solution.

[0029] Preferably, in step 1), the mass ratio of the solvent to the aluminum source calculated as alumina is 0.1 - 1:1, preferably 0.2 - 0.5:1.

[0030] Preferably, the amount of the forming aid used is 1-15 wt %, more preferably 3-8 wt %, of the aluminum source calculated as aluminum oxide.

[0031] Preferably, the amount of the peptizing agent used is 1-10 wt %, more preferably 3-7 wt %, of the aluminum source calculated as alumina.

[0032] Preferably, in step 2), the drying conditions include: temperature of 100-140° C.; time of 5-18 h.

[0033] The third aspect of the present invention provides a hydrogen fluoride adsorbent prepared by the preparation method of the hydrogen fluoride adsorbent according to the second aspect of the present invention, wherein the amount of larger pores with a pore size greater than 3 nm accounts for 85-95% of the total pores of the adsorbent, the amount of medium pores with a pore size of 1.5-3 nm accounts for 5-15% of the total pores of the adsorbent, and the amount of smaller pores with a pore size less than 1.5 nm accounts for 0-5% of the total pores of the adsorbent, and the specific surface area is 210-290 m 2 / g, where alumina is pure phase γ-Al 2 O 3 .

[0034] In a fourth aspect, the present invention provides use of the hydrogen fluoride adsorbent described in the first aspect of the present invention or the adsorbent described in the third aspect of the present invention in purifying hydrogen chloride gas.

[0035] When the hydrogen fluoride adsorbent provided by the present invention is used, the hydrogen fluoride molecules can be efficiently captured, so that the concentration of hydrogen fluoride in the purified gas is reduced to 0 ppm, thereby having a high hydrogen fluoride adsorption capacity, so that it can effectively meet the requirements of subsequent use conditions. In particular, in the byproduct hydrogen chloride gas containing hydrogen fluoride, γ-Al 2 O 3 It produces chemical adsorption with hydrogen fluoride and physical adsorption with hydrogen chloride. The stronger chemical adsorption ensures that hydrogen fluoride is adsorbed first and can replace the physically adsorbed hydrogen chloride, thus avoiding the negative influence of the atmosphere on the HF adsorption capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a scanning electron microscope image of a cross-section of a hydrogen fluoride adsorbent in Example 1, in which the grains are layered and the layers are interspersed with loose porous structures.

[0037] Figure 2 This is the X-ray diffraction analysis XRD analysis chart of Example 1.

[0038] Figure 3 This is the X-ray diffraction analysis XRD analysis diagram of Comparative Example 1.

[0039] Figure 4It is a cross-sectional scanning electron micrograph of an alumina adsorbent in Comparative Example 2, where the grains are lamellar and there is no loose and porous structure between the lamellae.

[0040] Figure 5 It is a cross-sectional scanning electron micrograph of an alumina adsorbent in Comparative Example 4, where the grains are flaky and there is a small amount of loose and porous structure between the flakes.

[0041] Figure 6 It is a cross-sectional scanning electron micrograph of an alumina adsorbent in Comparative Example 5, where the grains are flaky and there is no loose and porous structure between the flakes. Detailed implementation mode

[0042] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0043] The first aspect of the present invention provides a hydrogen fluoride adsorbent, wherein the hydrogen fluoride adsorbent is an alumina matrix adsorbent. The amount of larger pores with a pore diameter greater than 3 nm in the adsorbent accounts for 85 - 95% of the total pore volume of the adsorbent, the amount of medium pores with a pore diameter of 1.5 - 3 nm accounts for 5 - 15% of the total pore volume of the adsorbent, and the amount of smaller pores with a pore diameter less than 1.5 nm accounts for 0 - 5% of the total pore volume of the adsorbent. Its specific surface area is 210 - 290 m 2 / g, wherein the alumina is pure phase γ-Al 2 O 3 .

[0044] The inventors of the present invention have found through research that in the hydrogen fluoride adsorbent described in the first aspect of the present invention, the distribution of pores of various sizes has a significant impact on the hydrogen fluoride adsorption performance.

[0045] In the present invention, the proportions of the larger pores, medium pores, and smaller pores are obtained through pore size distribution tests using a physical adsorption instrument.

[0046] In the present invention, the pure phase refers to a single phase where the crystal phase of the alumina is only γ-Al 2 O 3 , and it does not contain other crystal phases except γ-Al 2 O 3 .

[0047] In the present invention, containing pure phase γ-Al 2 O 3The hydrogen fluoride adsorbent can chemically adsorb hydrogen fluoride, so it can ensure that hydrogen fluoride is preferentially chemically adsorbed. For example, in the by-product hydrogen chloride gas containing hydrogen fluoride, γ-Al 2 O 3 has a physical adsorption with hydrogen chloride. Therefore, while preferentially adsorbing hydrogen fluoride, it can displace the physically adsorbed hydrogen chloride, avoiding the negative impact of other atmospheres on the hydrogen fluoride adsorption capacity.

[0048] According to the present invention, when the specific surface area of the hydrogen fluoride adsorbent provided by the present invention is too large, there are more small pores, and the entry of hydrogen fluoride molecules into the small pores will block the pores, resulting in a decrease in adsorption performance; when the specific surface area of the adsorbent is too small, there are more large pores. Although the pore utilization rate is high, the number of pores is small, which will also lead to a decrease in adsorption performance. Therefore, in order to improve the performance of the adsorbent, preferably, the specific surface area of the hydrogen fluoride adsorbent is 220-255 m 2 / g; more preferably, the specific surface area of the hydrogen fluoride adsorbent is 230-250 m 2 / g.

[0049] The inventors have found through a large number of studies that in the hydrogen fluoride adsorbent provided by the present invention, the adsorption activity can be further significantly improved through a reasonable combination of specific surface area and average pore diameter. Therefore, preferably, the average pore diameter of the hydrogen fluoride adsorbent is 6-9 nm; more preferably, the average pore diameter of the hydrogen fluoride adsorbent is 6.7-8.5 nm; further preferably, the average pore diameter of the hydrogen fluoride adsorbent is 7.9-8.3 nm.

[0050] In the present invention, the average pore diameter of the hydrogen fluoride adsorbent is obtained by testing the average pore diameter with a physical adsorption instrument.

[0051] According to the present invention, the shape of the hydrogen fluoride adsorbent is not particularly limited, and common shapes in the art can be used, such as spherical and / or strip-shaped.

[0052] The inventors of the present invention have further found through in-depth research that when the adsorbent of the present invention is in large particles, it is not conducive to the full utilization of deep pores; when it is in small particles, the internal diffusion limitation can be partially eliminated, but too small particles will cause an increase in bed pressure drop and a decrease in particle strength. Therefore, in order to give full play to the activity of the adsorbent,

[0053] preferably, the particle size of the spherical shape is 1-2 mm; more preferably, the particle size of the spherical shape is 1.3-1.7 mm.

[0054] Preferably, the length of the strip is 1-2 mm, and the cross-sectional area is 0.19-6.25 mm 2 ; more preferably, the length of the strip is 1.3-1.7 mm, and the cross-sectional area is 1.25-5 mm 2 .

[0055] In the present invention, by using the specific surface area, average pore diameter and particle size as described above, the attenuation of mass transfer on the adsorption rate and adsorption efficiency can be effectively reduced, the internal diffusion in the fixed-bed adsorption process can be improved, and thus the adsorption performance can be significantly enhanced.

[0056] According to the present invention, the pure-phase γ-Al 2 O 3 grains are in a layered form, and there is a loose porous structure between the layers. Through the special grain morphology of the present invention, that is, the loose porous structure, hydrogen fluoride molecules can be efficiently captured, and the hydrogen fluoride concentration in the purified gas can be reduced to 0 ppm.

[0057] Through the above structure, the adsorption capacity of the hydrogen fluoride adsorbent can be further significantly improved.

[0058] The second aspect of the present invention provides a method for preparing a hydrogen fluoride adsorbent, wherein the method comprises the following steps:

[0059] 1) In the presence of a solvent, an aluminum source, a forming aid and a peptizing agent are brought into contact to obtain a contact product;

[0060] 2) The contact product is successively dried and calcined,

[0061] wherein the calcination includes a first-stage calcination, a second-stage calcination and a third-stage calcination;

[0062] The conditions for the first-stage calcination include: heating to 250°C - 300°C, with a heating rate of 15°C - 20°C / min;

[0063] The conditions for the second-stage calcination include: heating to 400°C - 450°C, with a heating rate of 3°C - 10°C / min, and maintaining for 15 - 60 min after heating;

[0064] The conditions for the third-stage calcination include: heating to 500°C - 650°C, with a heating rate of 1°C - 5°C / min, and maintaining for 60 - 300 min after heating.

[0065] In the present invention, by performing staged calcination and controlling the heating rate and calcination temperature, the specific surface area and average pore diameter can be effectively controlled, and in combination with the preparation method of the present invention, the specific surface area and average pore diameter of the prepared adsorbent can be within the range described in the first aspect of the present invention.

[0066] According to the present invention, the calcination conditions have a significant impact on the performance of the finally obtained adsorbent. Therefore, the control of the calcination conditions is particularly important. By adopting the specific calcination conditions of the present invention, that is, by adopting staged calcination conditions, the specific surface area and average pore diameter of the finally obtained adsorbent can be within the range required by the present invention, enabling the adsorbent of the present invention to have more excellent adsorption performance. Preferably, the conditions for the first-stage calcination include: heating to 260-290°C at a heating rate of 17-20°C / min; the conditions for the second-stage calcination include: heating to 420-440°C at a heating rate of 5-8°C / min, and maintaining for 30-50 min after heating; the conditions for the third-stage calcination include: heating to 550-600°C at a heating rate of 2-4°C / min, and maintaining for 180-300 min after heating.

[0067] According to the present invention, the aluminum source is not particularly limited and can be various aluminum sources commonly used in the art. However, in order to further improve the performance of the prepared adsorbent, preferably, the aluminum source is selected from one or more of pseudoboehmite, boehmite, and aluminum hydroxide.

[0068] Among them, preferably, the pseudoboehmite is selected from SB powder and / or dry gel powder.

[0069] According to the present invention, in step 1), the solvent can be a solvent commonly used in the field of adsorbents. In the present invention, since no pollutants are generated after water calcination, water is preferably used as the solvent in the present invention.

[0070] According to the present invention, in order to obtain a specific surface area and pore diameter within the scope of the present invention, preferably, in step 1), the mass ratio of the solvent to the aluminum source in terms of alumina is 0.1-1:1; more preferably, the mass ratio of the solvent to the aluminum source in terms of alumina is 0.2-0.5:1.

[0071] According to the present invention, in order to improve the performance of the adsorbent, preferably, the shaping aid is selected from one or more of lubricants, plasticizers, and pore expanders.

[0072] In the present invention, the lubricant is not particularly limited, and a lubricant commonly used in the art can be used. Preferably, the lubricant is selected from one or more of ethylene glycol, propylene glycol, and glycerol.

[0073] In the present invention, the plasticizer is not particularly limited, and a plasticizer commonly used in the art can be used. Preferably, the plasticizer is selected from hydroxyethyl cellulose and / or polyethylene glycol.

[0074] In the present invention, there is no particular limitation on the pore former, and a commonly used pore former in the art can be used. Preferably, the pore former is selected from one or more of sesbania powder, starch, and sawdust.

[0075] More preferably, the shaping aid is selected from sesbania powder and / or starch.

[0076] In the present invention, there is no particular limitation on the peptizing agent, and a commonly used peptizing agent in the art can be used. Preferably, the peptizing agent is selected from one or more of acetic acid, nitric acid, citric acid, formic acid, and phosphoric acid solution; more preferably, it is nitric acid solution.

[0077] According to the present invention, the concentration of the peptizing agent is 20 - 70% by weight.

[0078] Preferably, the dosage of the shaping aid is 1 - 15% by weight of the aluminum source calculated as alumina; more preferably, the dosage of the shaping aid is 3 - 8% by weight of the aluminum source calculated as alumina.

[0079] Preferably, the dosage of the peptizing agent is 1 - 10% by weight of the aluminum source calculated as alumina; more preferably, the dosage of the peptizing agent is 3 - 7% by weight of the aluminum source calculated as alumina.

[0080] According to the present invention, for the contacting operation, the aluminum source, shaping aid, solvent, and peptizing agent need to be mixed and formed. The mixing and forming operation can use a commonly used mixing method in the art, and only need to mix them evenly. After mixing and forming, granulation is carried out. The granulation can use a commonly used granulation method in the art to obtain a particle size and cross-sectional area within the scope of the present invention. The mixing operation can be carried out at room temperature, for example, the temperature is 5 - 45°C.

[0081] According to a preferred embodiment of the present invention, first, the aluminum source and the shaping aid are mixed, and then the solvent and the peptizing agent are sprayed in and mixed and formed continuously.

[0082] According to a preferred embodiment of the present invention, in step 1), in order to complete the mixing operation and the granulation operation in one step, the contacting operation is carried out using a rolling ball machine.

[0083] In particular, when a liquid shaping aid such as ethylene glycol, propylene glycol, and glycerol is used as the shaping aid, in order to mix evenly, it is preferably mixed with the solvent and the peptizing agent, and then contacted with the aluminum source.

[0084] According to the present invention, in order to further control the particle size of the obtained adsorbent and further improve the adsorption performance stability of the adsorbent, after completing step 1), a sieving step can also be included.

[0085] In the present invention, when the product of step 1) is spherical, sieving can be carried out before step 2) or after the drying or calcination operation of step 2) is completed. Preferably, the particle size of the spherical precursor after sieving is 1-2 mm; more preferably, the particle size of the spherical shape is 1.3-1.7 mm.

[0086] In the present invention, when the product of step 1) is bar-shaped, first perform the drying of step 2), and then crush and sieve. Preferably, the length of the bar-shaped precursor after sieving is 1-2 mm, and the cross-sectional area is 0.19-6.25 mm 2 ; more preferably, the length of the bar is 1.3-1.7 mm, and the cross-sectional area is 1.25-5 mm 2 .

[0087] According to the present invention, in step 2), the shaped product obtained by contacting in step 1) is dried. Preferably, the drying conditions include: the temperature is 100-140 °C; the time is 5-18 h.

[0088] In the third aspect of the present invention, there is provided a hydrogen fluoride adsorbent prepared by the preparation method of the hydrogen fluoride adsorbent described in the second aspect of the present invention. This hydrogen fluoride adsorbent is an alumina matrix adsorbent. The amount of larger pores with a pore diameter greater than 3 nm in the adsorbent accounts for 85-95% of the total pore volume of the adsorbent, the amount of medium pores with a pore diameter of 1.5-3 nm accounts for 5-15% of the total pore volume of the adsorbent, and the amount of smaller pores with a pore diameter less than 1.5 nm accounts for 0-5% of the total pore volume of the adsorbent. Its specific surface area is 210-290 m 2 / g, wherein the alumina is pure-phase γ-Al 2 O 3 .

[0089] The hydrogen fluoride adsorbent described in the third aspect of the present invention may have the same or similar characteristics or properties as the hydrogen fluoride adsorbent described in the first aspect of the present invention, which will not be elaborated here.

[0090] The fourth aspect of the present invention provides the application of the hydrogen fluoride adsorbent described in the first aspect of the present invention or the hydrogen fluoride adsorbent described in the third aspect of the present invention in the field of hydrogen chloride gas purification.

[0091] The present invention will be described in detail below through examples, but the present invention is not limited to the following examples.

[0092] In the following examples and comparative examples, the specific surface area of the hydrogen fluoride adsorbent was obtained by BET specific surface area test of a physical adsorption instrument;

[0093] In the following examples and comparative examples, the average pore diameter of the hydrogen fluoride adsorbent was obtained by average pore diameter test of a physical adsorption instrument;

[0094] In the following examples and comparative examples, the proportions of macropores, mesopores and micropores of the hydrogen fluoride adsorbent were obtained by testing the pore size distribution with a physical adsorption instrument.

[0095] In the following examples and comparative examples, the raw materials and equipment information used is as follows:

[0096] Sesbania powder: purchased from Beijing Haifuda Technology Co., Ltd., model MK5

[0097] Rolling ball machine: purchased from EIRICH, model EL5 Eco

[0098] Manufacturer and model of the test example determination device: Tianjin Baoming Hongye Technology Co., Ltd., SY-SCCHF1

[0099] Example 1

[0100] 1) Put 305.9 g of aluminum hydroxide and 12 g of sesbania powder into a rolling ball machine. After mixing evenly, spray water and nitric acid solution (concentration 67 wt%) while rolling into balls, and sieve to obtain 1.3 - 1.7 mm adsorbent precursor pellets. The mass ratio of water to aluminum hydroxide calculated as alumina is 0.2:1. The dosage of sesbania powder in the precursor pellets is 6 wt% of the aluminum source calculated as alumina, and the dosage of nitric acid solution is 6 wt% of the aluminum source calculated as alumina;

[0101] 2) Dry the adsorbent precursor pellets at 110 °C for 12 h, then transfer them to a muffle furnace for the first-stage roasting: heat up to 260 °C at a heating rate of 17 °C / min; then carry out the second-stage roasting: heat up to 420 °C at a heating rate of 5 °C / min, and maintain for 30 min after heating; then carry out the third-stage roasting: heat up to 550 °C at a heating rate of 2 °C / min, and maintain for 180 min after heating to obtain adsorbent S1.

[0102] The cross-sectional scanning electron micrograph of adsorbent S1 is as Figure 1 shown, and it can be seen from Figure 1 that the alumina grains are layered, and there are loose porous structures between the layers.

[0103] In addition, it can be seen from the X-ray diffraction analysis (XRD) of Figure 2 that the alumina in adsorbent S1 is pure-phase γ-Al 2 O 3 .

[0104] Example 2

[0105] The preparation method is the same as that of Example 1, except that

[0106] In step 2), transfer it to a muffle furnace for the first-stage roasting: heat up to 290 °C at a heating rate of 20 °C / min; then carry out the second-stage roasting: heat up to 440 °C at a heating rate of 8 °C / min, and maintain for 50 min after heating; then carry out the third-stage roasting: heat up to 600 °C at a heating rate of 4 °C / min, and maintain for 300 min after heating to obtain adsorbent S2.

[0107] From the cross-sectional scanning electron micrograph of adsorbent S2, it can be seen that the alumina grains of adsorbent S2 are layered, and there are loose and porous structures between the layers.

[0108] In addition, it can be seen from XRD that the alumina in adsorbent S2 is pure-phase γ-Al 2 O 3 。

[0109] Example 3

[0110] The preparation method is the same as that of Example 1, except that

[0111] In step 1), put 322.6 g of dry glue powder and 12 g of starch into a rolling ball machine. After mixing evenly, spray water and nitric acid solution (concentration 67 wt%) while rolling ball forming, and sieve to obtain 1.3 - 1.7 mm adsorbent precursor pellets. The mass ratio of water to the aluminum source calculated as alumina is 0.37:1. The dosage of starch in the precursor pellets is 6 wt% of the aluminum source calculated as alumina, and the dosage of nitric acid solution is 6 wt% of the aluminum source calculated as alumina;

[0112] In step 2), transfer it to a muffle furnace for the first-stage roasting: heat up to 275 °C at a heating rate of 18 °C / min; then carry out the second-stage roasting: heat up to 430 °C at a heating rate of 7 °C / min, and maintain for 45 min after heating; then carry out the third-stage roasting: heat up to 585 °C at a heating rate of 2.5 °C / min, and maintain for 240 min after heating to obtain adsorbent S3.

[0113] From the cross-sectional scanning electron micrograph of adsorbent S3, it can be seen that the alumina grains of adsorbent S3 are layered, and there are loose and porous structures between the layers.

[0114] In addition, it can be seen from XRD that the alumina in adsorbent S3 is pure-phase γ-Al 2 O 3 。

[0115] Example 4

[0116] The preparation method is the same as that of Example 1, except that

[0117] In step 2), transfer to a muffle furnace and carry out the first stage of calcination: heat to 250°C at a heating rate of 15°C / min; then carry out the second stage of calcination: heat to 420°C at a heating rate of 5°C / min, and maintain for 30 minutes after heating; then carry out the third stage of calcination: heat to 550°C at a heating rate of 2°C / min, and maintain for 180 minutes after heating to obtain adsorbent S4.

[0118] From the scanning electron micrograph of the cross section of the adsorbent S4, it can be seen that the alumina grains of the adsorbent S4 are layered, and loose porous structures are interspersed between the layers.

[0119] In addition, it can be seen from XRD that the alumina in adsorbent S4 is pure phase γ-Al 2 O 3 .

[0120] Example 5

[0121] The preparation method is the same as in Example 1, except that

[0122] In step 2), the mixture is transferred to a muffle furnace and calcined in the first stage: the temperature is raised to 260°C at a heating rate of 17°C / min; the temperature is raised to 450°C at a heating rate of 10°C / min, and the temperature is maintained for 60 minutes; the temperature is raised to 550°C at a heating rate of 2°C / min, and the temperature is maintained for 180 minutes to obtain adsorbent S5.

[0123] From the scanning electron microscope image of the cross section of the adsorbent S5, it can be seen that the alumina grains of the adsorbent S5 are layered, and loose porous structures are interspersed between the layers.

[0124] In addition, it can be seen from XRD that the alumina in the adsorbent S5 is pure phase γ-Al 2 O 3 .

[0125] Example 6

[0126] The preparation method is the same as in Example 1, except that

[0127] In step 2), transfer to a muffle furnace and carry out the first stage of calcination: heat to 260°C at a heating rate of 17°C / min; then carry out the second stage of calcination: heat to 420°C at a heating rate of 5°C / min, and maintain for 30 minutes after heating; then carry out the third stage of calcination: heat to 650°C at a heating rate of 1°C / min, and maintain for 180 minutes after heating to obtain adsorbent S6.

[0128] From the scanning electron micrograph of the cross section of the adsorbent S6, it can be seen that the alumina grains of the adsorbent S6 are layered, and loose porous structures are interspersed between the layers.

[0129] In addition, it can be seen from the XRD that the alumina in adsorbent S6 is pure-phase γ-Al 2 O 3 .

[0130] Example 7

[0131] The preparation method is the same as that of Example 1, except that in step 1), the dosage of the nitric acid solution is 8% by weight of the aluminum source calculated as alumina, and adsorbent S7 is obtained.

[0132] It can be seen from the cross-sectional scanning electron micrograph of adsorbent S7 that the alumina grains of adsorbent S7 are layered, and a loose porous structure is interspersed between the layers.

[0133] In addition, it can be seen from the XRD that the alumina in adsorbent S7 is pure-phase γ-Al 2 O 3 .

[0134] Comparative Example 1

[0135] The preparation method is the same as that of Example 1, except that two-stage calcination is carried out.

[0136] In step 2), transfer it to a muffle furnace for the first-stage calcination: heat up to 260 °C at a heating rate of 17 °C / min; then carry out the second-stage calcination: heat up to 400 °C at a heating rate of 5 °C / min, and maintain for 300 min after heating to obtain adsorbent D1.

[0137] It can be seen from the cross-sectional scanning electron micrograph of adsorbent D1 that the alumina grains of adsorbent D1 are layered, and there is a loose porous structure between the layers.

[0138] However, it can be seen from the Figure 3 XRD that the alumina in adsorbent D1 is a mixed phase of boehmite and γ-Al 2 O 3 mixed phase.

[0139] Comparative Example 2

[0140] The preparation method is the same as that of Example 1, except that

[0141] in step 2), gradient calcination is not carried out, and it is transferred to a muffle furnace for direct calcination at a heating rate of 20 °C / min and a calcination temperature of 550 °C, and maintained for 2.5 h at this time to obtain adsorbent D2.

[0142] The cross-sectional scanning electron micrograph of adsorbent D2 is as Figure 4 shown, and it can be seen from Figure 4 that the alumina grains are layered but there is no loose porous structure between the layers.

[0143] In addition, it can be seen from the XRD that the alumina in adsorbent D2 is pure-phase γ-Al 2 O 3 .

[0144] Comparative Example 3

[0145] The preparation method is the same as that of Example 1, except that

[0146] in step 2), it is transferred to a muffle furnace for the first-stage calcination: heating to 260 °C at a heating rate of 17 °C / min; then for the second-stage calcination: heating to 420 °C at a heating rate of 20 °C / min, and maintaining for 30 min after heating; then for the third-stage calcination: heating to 550 °C at a heating rate of 2 °C / min, and maintaining for 300 min after heating to obtain adsorbent D3.

[0147] It can be seen from the cross-sectional scanning electron micrograph of adsorbent D3 that the alumina grains of adsorbent D3 are layered but there is no loose and porous structure between the layers.

[0148] In addition, it can be seen from the XRD that the alumina in adsorbent D3 is pure-phase γ-Al 2 O 3 .

[0149] Comparative Example 4

[0150] The preparation method is the same as that of Example 1, except that

[0151] in step 2), it is transferred to a muffle furnace for the first-stage calcination: heating to 260 °C at a heating rate of 2 °C / min; then for the second-stage calcination: heating to 420 °C at a heating rate of 5 °C / min, and maintaining for 100 min after heating; then for the third-stage calcination: heating to 550 °C at a heating rate of 2 °C / min, and maintaining for 300 min after heating to obtain adsorbent D4.

[0152] The cross-sectional scanning electron micrograph of adsorbent D4 is as Figure 5 shown. It can be seen from Figure 5 that the alumina grains are flaky and there is a small amount of loose and porous structure between the flakes.

[0153] In addition, it can be seen from the XRD that the alumina in adsorbent D4 is pure-phase γ-Al 2 O 3 .

[0154] Comparative Example 5

[0155] The preparation method is the same as that of Example 1, except that in step 1), the amount of the nitric acid solution (concentration: 67%) is 18% by weight of the aluminum source based on alumina to obtain adsorbent D5.

[0156] The cross-sectional scanning electron micrograph of adsorbent D5 is as shown in Figure 6 and it can be seen from Figure 6 that the alumina grains are flaky but there is no loose and porous structure between the flakes.

[0157] In addition, it can be seen from XRD that the alumina in adsorbent D5 is pure phase γ-Al 2 O 3 .

[0158] Comparative Example 6

[0159] 1) Put 200 g of calcium fluoride and 12 g of sesbania powder into a rolling ball machine. After mixing evenly, spray water while rolling the balls to form pellets, and then screen them to obtain adsorbent precursor pellets with a size of 1.3 - 1.7 mm. The mass ratio of water to calcium fluoride is 0.38:1, and the dosage of sesbania powder in the precursor pellets is 6 wt% of calcium fluoride;

[0160] 2) Dry the adsorbent precursor pellets at 110 °C for 12 h, then transfer them to a muffle furnace for the first-stage roasting: heat up to 260 °C at a heating rate of 17 °C / min; then carry out the second-stage roasting: heat up to 420 °C at a heating rate of 5 °C / min, and maintain for 30 min after heating; then carry out the third-stage roasting: heat up to 550 °C at a heating rate of 2 °C / min, and maintain for 180 min after heating to obtain adsorbent D6.

[0161] Test the parameters of adsorbents S1 - S7 and D1 - D6 prepared in the above examples and comparative examples respectively. The results are shown in Table 1.

[0162] Table 1

[0163]

[0164] Test Example 1

[0165] This test example is used to determine the breakthrough time. The specific method is as follows:

[0166] Test device - The hydrogen fluoride adsorption experiment uses an adsorption device designed by the laboratory itself. This set of devices includes a gas distribution system, a fixed-bed adsorption column, a tail gas hydrogen fluoride concentration test system, and a tail gas adsorption system.

[0167] Test conditions - The inlet gas is a hydrogen fluoride standard gas with a concentration of 1000 ppm (nitrogen-based), the gas flow rate is 750 mL / min, the adsorbent dosage is 2.5 g, the adsorption temperature is 25 °C, and the diameter of the adsorption column is 1 cm.

[0168] Test method - During the experiment, a mixed solution of 0.0005 mol / L sodium hydroxide solution and a small amount of phenolphthalein reagent was used as the end-point indicator. The time required for the solution to change from purple to colorless was recorded, and the breakthrough time of the system itself for adsorbing hydrogen fluoride and the time required for hydrogen fluoride to consume sodium hydroxide in the indicator were subtracted. The actual breakthrough time of the adsorbent bed was obtained. The actual breakthrough time shows the hydrogen fluoride adsorption capacity of the adsorbent.

[0169] The breakthrough times of the adsorbents S1-S7 and D1-D6 prepared by the examples and comparative examples were tested according to the above test method. The longer the breakthrough time, the better the hydrogen fluoride adsorption performance. The results are shown in Table 2:

[0170] Table 2

[0171] Adsorbent Breakthrough time (S) S1 385 S2 390 S3 399 S4 317 S5 325 S6 322 S7 330 D1 201 D2 100 D3 118 D4 134 D5 88 D6 29

[0172] Test Example 2

[0173] The hydrogen fluoride concentration in the purified gas passing through the adsorbents S1-S7 was measured to be 0 ppm in the first 30 minutes using a German Drager X-am 5100 detector, indicating that the patented adsorbent has excellent deep defluorination ability.

[0174] 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 technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A hydrogen fluoride adsorbent, characterized in that, The hydrogen fluoride adsorbent is an alumina matrix adsorbent. The amount of larger pores with a pore diameter greater than 3 nm accounts for 85 - 95% of the total pores of the adsorbent, the amount of medium pores with a pore diameter of 1.5 - 3 nm accounts for 5 - 15% of the total pores of the adsorbent, and the amount of smaller pores with a pore diameter less than 1.5 nm accounts for 0 - 5% of the total pores of the adsorbent. Its specific surface area is 210 - 290 m 2 / g, where the alumina is pure-phase γ-Al 2 O 3 .

2. The hydrogen fluoride adsorbent according to claim 1, wherein, The specific surface area of the hydrogen fluoride adsorbent is 210 - 290 m 2 / g, preferably 220 - 255 m 2 / g, more preferably 230 - 250 m 2 / g; Preferably, the average pore diameter of the hydrogen fluoride adsorbent is 6 - 9 nm, more preferably 6.7 - 8.5 nm, and further preferably 7.9 - 8.3 nm.

3. The hydrogen fluoride adsorbent according to claim 1 or 2, wherein, the hydrogen fluoride adsorbent is spherical and / or strip-shaped; Preferably, the particle size of the spherical shape is 1 - 2 mm, more preferably 1.3 - 1.7 mm; Preferably, the length of the strip is 1-2 mm, and the cross-sectional area is 0.19-6.25 mm 2 ; More preferably, the length of the strip is 1.3 - 1.7 mm, and the cross-sectional area is 1.25 - 5 mm 2 .

4. The hydrogen fluoride adsorbent according to any one of claims 1 - 3, wherein, The pure phase γ-Al of the hydrogen fluoride adsorbent 2 O 3 The crystal grains are lamellar, and there is a loose porous structure between the lamellae.

5. A preparation method of a hydrogen fluoride adsorbent, characterized in that, this method comprises the following steps: 1) In the presence of a solvent, make an aluminum source, a shaping aid, and a peptizing agent contact to obtain a contact product; 2) Dry and calcine the contact product in sequence, wherein, the calcination includes a first-stage calcination, a second-stage calcination, and a third-stage calcination; The conditions of the first-stage calcination include: heating to 250°C - 300°C, with a heating rate of 15°C - 20°C / min; The conditions of the second-stage calcination include: heating to 400°C - 450°C, with a heating rate of 3°C - 10°C / min, and maintaining for 15 - 60 min after heating; The conditions of the third-stage calcination include: heating to 500°C - 650°C, with a heating rate of 1°C - 5°C / min, and maintaining for 60 - 300 min after heating.

6. The preparation method according to claim 5, wherein, the aluminum source is selected from one or more of pseudo-boehmite, boehmite, and aluminum hydroxide; Preferably, the shaping aid is selected from one or more of a lubricant, a plasticizer, and a pore-expanding agent; Preferably, the lubricant is selected from one or more of ethylene glycol, propylene glycol, and glycerol; Preferably, the plasticizer is selected from hydroxyethyl cellulose and / or polyethylene glycol; Preferably, the pore-expanding agent is selected from one or more of sesbania powder, starch, and sawdust; More preferably, the shaping aid is selected from sesbania powder and / or starch; Preferably, the peptizing agent is selected from one or more of acetic acid, nitric acid, citric acid, formic acid, and phosphoric acid solution; more preferably nitric acid solution.

7. The preparation method according to claim 5 or 6, wherein, In step 1), the mass ratio of the solvent to the aluminum source calculated as alumina is 0.1 - 1:1, preferably 0.2 - 0.5:1; Preferably, the dosage of the shaping aid is 1 - 15% by weight of the aluminum source calculated as alumina, more preferably 3 - 8% by weight; Preferably, the dosage of the peptizing agent is 1 - 10% by weight of the aluminum source calculated as alumina, more preferably 3 - 7% by weight.

8. The preparation method according to any one of claims 5 - 7, wherein, In step 2), the conditions of the drying include: temperature is 100 - 140°C; time is 5 - 18 h.

9. A hydrogen fluoride adsorbent prepared by the preparation method according to any one of claims 5-8, wherein the amount of larger pores with a pore diameter greater than 3 nm accounts for 85-95% of the total pore volume of the adsorbent, the amount of medium pores with a pore diameter of 1.5-3 nm accounts for 5-15% of the total pore volume of the adsorbent, and the amount of smaller pores with a pore diameter less than 1.5 nm accounts for 0-5% of the total pore volume of the adsorbent, and its specific surface area is 210-290 m 2 / g, wherein, The alumina is in the pure phase of γ-Al 2 O 3 .

10. Application of the hydrogen fluoride adsorbent according to any one of claims 1 - 4 and 9 in the purification of hydrogen chloride gas.

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