Flame-retardant porous adsorbent, preparation method and application thereof

Abstract

The present application relates to a kind of flame-retardant porous adsorbent, preparation method and its application.The preparation method of the flame-retardant porous adsorbent is simple, high in mechanical strength, strong in water heat stability, with good volatile organic compound adsorption performance, long service life and the like.

Description

Technical Field

[0001] This invention relates to a flame-retardant porous adsorbent. More specifically, this invention relates to a flame-retardant porous adsorbent and its preparation method. This invention also relates to the application of the flame-retardant porous adsorbent in the adsorption and treatment of volatile organic compounds. Background Technology

[0002] In recent years, with increasingly stringent national environmental protection requirements, recovery technologies such as adsorption, catalytic oxidation, high-temperature incineration, absorption, condensation, and membrane separation have been widely applied to the recovery / treatment of various waste gases containing volatile organic compounds (VOCs). Among these, mature treatment methods exist for industrial waste gases with relatively stable flow rates and concentrations, such as using catalytic oxidation to treat PTA oxidation tail gas. However, for VOC-containing waste gases with fluctuating concentrations and flow rates, a single treatment method is unlikely to achieve ideal results. It is worth noting that for large air volumes (>10000 Nm³),... 3 / h), low VOCs concentration (<500mg / m³) 3 For waste gas containing VOCs, methods such as condensation, membrane separation, and absorption are often insufficient for achieving satisfactory results. While high-temperature incineration can achieve treatment standards, it requires the replenishment of large amounts of flammable gases, such as natural gas, to maintain the combustion temperature, resulting in high operating costs. Adsorption-catalytic oxidation has become a common method for treating this difficult-to-treat waste gas in recent years. The adsorbent in this process is typically honeycomb activated carbon. However, honeycomb activated carbon has small pore sizes (generally micropores), making it unsuitable for adsorbing larger VOC molecules. Furthermore, honeycomb activated carbon is not heat-resistant in the presence of air, exhibits poor hydrothermal stability, and the adsorbed substances undergo self-polymerization during desorption, leading to the formation of localized hot spots and affecting the safety and reliability of the equipment. For example, Chinese invention patent CN106395817A discloses a method for preparing honeycomb activated carbon, but its shortcomings include a relatively large amount of material used with low effective utilization and a small adsorption capacity for gases. CN105363411B discloses a method for preparing a molecular sieve adsorption profile, which involves coating the molecular sieve with glass fiber. However, the adhesion of the molecular sieve coating on the glass fiber is not high, and it may fall off during the process, affecting long-term use.

[0003] Therefore, there is an urgent need in the existing technology for an adsorbent that can be manufactured at low cost, has good adsorption properties for VOCs and excellent stability, and can be used for a long time. Summary of the Invention

[0004] In view of the technical problems in the prior art, the inventors, through diligent research based on the prior art, discovered that by using at least one of attapulgite and kaolin as the original matrix, and further combining it with an appropriate inorganic porous solid, a porous adsorbent can be prepared. This adsorbent has good adsorption performance of volatile organic compounds (also known as VOCs or VOCs) and stable performance, thus completing the present invention.

[0005] Specifically, the present invention provides a flame-retardant porous adsorbent, characterized in that it contains at least one primary matrix selected from attapulgite and kaolin, and at least one inorganic material selected from inorganic porous solids. Based on the total mass of the adsorbent, the content of the primary matrix is ​​10-100% by mass, preferably 10-99.5% by mass, more preferably 20-99% by mass, and the content of the inorganic material is 0-90% by mass, preferably 0.5-90% by mass, more preferably 5-80% by mass, further preferably 8-70% by mass, and even more preferably the balance.

[0006] This invention also provides a method for preparing a flame-retardant porous adsorbent, characterized by comprising the following steps:

[0007] (1) A plastic mixed contact body is prepared by mixing and contacting at least one original matrix selected from attapulgite and kaolin, at least one inorganic material selected from inorganic porous solids, a binder, and water; wherein, relative to the total amount of the original matrix and the inorganic material, the content of the original matrix is ​​10 to 100% by mass, preferably 10 to 99.5% by mass, more preferably 20 to 99% by mass, and the content of the inorganic material is 0 to 90% by mass, preferably 0.5 to 90% by mass, more preferably 5 to 80% by mass, further preferably 8 to 70% by mass, and even more preferably the balance;

[0008] (2) Optionally, the plastic mixed contact body is molded to obtain a porous adsorbent blank;

[0009] (3) The mixed contact body of step (1) or the porous adsorbent blank of step (2) is calcined to obtain a flame-retardant porous adsorbent.

[0010] The present invention also provides a porous matrix comprising the flame-retardant porous adsorbent described above.

[0011] The present invention also provides the use of the flame-retardant porous adsorbent described above in a porous matrix (preferably a porous carrier).

[0012] The present invention also provides the use of the flame-retardant porous adsorbent described above for adsorbing volatile organic compounds.

[0013] Technical effect

[0014] The preparation method of the flame-retardant porous adsorbent of the present invention is simple, low in cost, and has good hydrothermal stability. The adsorbent can be designed according to the molecular size of the adsorbate, and can effectively adsorb and remove VOCs.

[0015] The flame-retardant porous adsorbent of the present invention can efficiently and stably absorb VOCs. Furthermore, since the adsorbent of the present invention is a flame-retardant adsorbent, the adsorbed VOCs can be rapidly desorbed into the combustion reactor by high-temperature desorption, which avoids the defects of local hot spots (potential for smoldering) found in activated carbon adsorbents. It can also efficiently and stably regenerate the adsorbent, thereby improving the VOCs treatment efficiency and extending the service life of the adsorbent. Detailed Implementation

[0016] The embodiments of the present invention will be described in more detail below with reference to specific examples. However, those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and should not be considered as limiting the scope of protection of the present invention. Rather, the present invention is intended to cover all alternatives, modifications, and equivalents that may be included within the scope of the present invention as defined by the claims.

[0017] Unless otherwise specified, the various embodiments of the present invention can be combined in any way, and the resulting transformations, modifications, and alterations of the technical solutions are also included within the scope of the present invention and do not exceed the scope of the present invention.

[0018] Attapulgite, also known as palygorskite, is a natural hydrated clay material rich in magnesium aluminum silicate with a layered chain structure. Its basic structural unit is a sandwich structure consisting of two layers of silicon-oxygen tetrahedra and one layer of magnesium (aluminum)-oxygen octahedra. The ideal unit cell formula is (Mg)₅Si₈O. 20 (OH)2(OH2)4·4H2O. Attapulgite clay exhibits a high specific surface area, open mesoporous-microporous composite channels, and good thermal stability, making it suitable as an adsorbent for VOCs. Furthermore, it is similar to inorganic materials such as molecular sieves, SiO2, Al2O3, and TiO2, all of which belong to inorganic mineral materials. It has good kneading properties after mixing, and the adsorbent can be designed according to the molecular size of the adsorbate.

[0019] This invention provides a flame-retardant porous adsorbent, characterized in that it contains at least one primary matrix selected from attapulgite and kaolin, and at least one inorganic material selected from inorganic porous solids. Based on the total mass of the adsorbent, the content of the primary matrix is ​​10-100% by mass, preferably 10-99.5% by mass, more preferably 20-99% by mass, and the content of the inorganic material is 0-90% by mass, preferably 0.5-90% by mass, more preferably 5-80% by mass, further preferably 8-70% by mass, and even more preferably the balance.

[0020] In one embodiment of the invention, the adsorbent is substantially composed of the original matrix and the inorganic material. In another embodiment of the invention, the adsorbent is composed only of the original matrix and the inorganic material.

[0021] In one embodiment of the present invention, the content of the original matrix is ​​10 to 100% by mass, preferably 10 to 99.5% by mass, and more preferably 20 to 99% by mass, based on the total mass of the adsorbent.

[0022] In one embodiment of the present invention, based on the total mass of the adsorbent, the content of the inorganic material is 0-90% by mass, preferably 0.5-90% by mass, more preferably 5-80% by mass, even more preferably 8-70% by mass, and even more preferably the balance.

[0023] In this invention, the attapulgite clay can be any type of attapulgite clay known in the art, and it can be a commercially available product. The kaolin clay can also be any type of kaolin clay known in the art, and it can be a commercially available product.

[0024] In this invention, the inorganic porous solids can include refractory oxides of metals from Groups IIA, IIIA, IVA, or IVB of the periodic table (such as silicon dioxide, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide, or thorium oxide), or any refractory composite oxide of these metals (such as aluminum silicate, aluminum magnesium oxide, silicon titanium oxide, magnesium titanium oxide, and aluminum titanium oxide), as well as clay, molecular sieves, mica, montmorillonite, bentonite, and diatomaceous earth.

[0025] In one embodiment of the present invention, the inorganic porous solid is preferably selected from at least one of silicon dioxide, aluminum oxide, magnesium oxide, aluminum silicate, aluminum magnesium oxide, silicon dioxide, titanium dioxide, molecular sieve and montmorillonite.

[0026] In this invention, the molecular sieve can be any molecular sieve known in the art. For example, the molecular sieve can be selected from one or more combinations of type A molecular sieve, type X molecular sieve, type Y molecular sieve, ZSM series, SAPO, AIPO, mordenite molecular sieve, SBA, and MCM.

[0027] In this invention, silicon dioxide, aluminum oxide, magnesium oxide, aluminum silicate, aluminum magnesium oxide, silicon titanium dioxide, titanium dioxide, molecular sieves, and montmorillonite can be any inorganic material known in the art, can be manufactured by known methods, or can be any commercially available product.

[0028] In one embodiment of the present invention, the flame-retardant porous adsorbent BET has a specific surface area of ​​100~800 m². 2 ·g -1 Preferred depth: 110~800m 2 ·g -1 The most probable pore size is 2~16nm, preferably 3~14nm, and the pore volume is 0.15~1.2ml·g. -1 Preferably, the diameter is 0.2~1.2 m. 2 ·g -1 .

[0029] The adsorbent of the present invention retains at least 80% of its positive pressure strength before and after the hydrothermal stability test, more preferably at least 85%, and even more preferably at least 90%. The hydrothermal stability test involves purging the adsorbent with 130°C water vapor for 10 hours, followed by purging with dry hot air until the weight of the adsorbent no longer changes. The positive pressure strength of the adsorbent is then measured before and after the test.

[0030] Positive pressure strength retention rate = (Positive pressure strength after hydrothermal stability test) / (Positive pressure strength before hydrothermal stability test) * 100%

[0031] The positive pressure strength of the adsorbent of the present invention was determined according to the standard method of GB / T 5072-2008.

[0032] In one embodiment of the present invention, the flame-retardant porous adsorbent can be molded into a macroscopic adsorbent molded body with an appearance of spheres, cubes, cuboids, cylinders, Raschig rings, etc.

[0033] In one embodiment of the present invention, when the adsorbent is molded into an adsorbent body, the adsorbent body may have macroscopic channels, which can be one or more of the following pore structures: circular, square, triangular, hexagonal, or rhombic. These macroscopic channels can be arranged in an ordered or disordered manner on the adsorbent body, preferably as uniformly ordered honeycomb channels. Generally, to reduce adsorption resistance, the macroscopic channels on the adsorbent body are permeable.

[0034] In one embodiment of the present invention, the cross-sectional area of ​​a single pore in the macroscopic pores of the macroscopic adsorbent molded body is 1 mm. 2 ~80mm 2 Preferably 1mm 2~40mm 2 The hole wall thickness is 1~4mm, preferably 1~2.5mm.

[0035] In one embodiment of the present invention, the flame-retardant porous adsorbent has a positive pressure strength of 2 to 8 MPa, preferably 3 to 6 MPa, as determined by the standard method of GB / T 5072-2008, and a lateral pressure strength of 0.1 to 2 MPa, preferably 0.25 to 1.5 MPa.

[0036] Without impairing the effects of the present invention, the porous adsorbent may optionally contain other auxiliary agents. Examples of such auxiliary agents include various metal oxides and various inert organic porous solids, in addition to the inorganic materials described above. The amount of such auxiliary agent used is 1 to 50% by mass relative to the total mass of the porous adsorbent, preferably 5 to 30% by mass. In one embodiment of the present invention, the porous adsorbent does not contain carbonaceous materials (including but not limited to activated carbon, carbon fibers, etc.).

[0037] This invention also provides a method for preparing a flame-retardant porous adsorbent, characterized by comprising the following steps:

[0038] (1) A plastic mixed contact body is prepared by mixing and contacting at least one original matrix selected from attapulgite and kaolin, at least one inorganic material selected from inorganic porous solids, a binder, and water; wherein, relative to the total amount of the original matrix and the inorganic material, the content of the original matrix is ​​10 to 100% by mass, preferably 10 to 99.5% by mass, more preferably 20 to 99% by mass, and the content of the inorganic material is 0 to 90% by mass, preferably 0.5 to 90% by mass, more preferably 5 to 80% by mass, further preferably 8 to 70% by mass, and even more preferably the balance;

[0039] (2) Optionally, the plastic mixed contact body is molded to obtain a porous adsorbent blank;

[0040] (3) The mixed contact body of step (1) or the porous adsorbent blank of step (2) is calcined to obtain a flame-retardant porous adsorbent.

[0041] In one embodiment of the present invention, in step (1) of the above preparation method, at least one original matrix selected from attapulgite and kaolin is used directly without any pretreatment.

[0042] In the preparation method of this invention, the attapulgite can be any attapulgite known in the art, and it can be a commercially available product. The kaolin can be any kaolin known in the art, and it can be a commercially available product.

[0043] In the preparation method of the present invention, in step (1) above, the inorganic porous solid can be refractory oxides of metals of Group IIA, IIIA, IVA or IVB of the periodic table (such as silicon dioxide (also known as silicon oxide or silica gel), aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide or thorium oxide, etc.), or any refractory composite oxide of these metals (such as aluminum silicate, aluminum magnesium oxide, silicon titanium oxide, magnesium titanium oxide and aluminum titanium oxide, etc.), as well as clay, molecular sieve, mica, montmorillonite, bentonite and diatomaceous earth, etc.

[0044] In one embodiment of the present invention, the inorganic porous solid is preferably selected from at least one of silicon dioxide, aluminum oxide, magnesium oxide, aluminum silicate, aluminum magnesium oxide, silicon dioxide, titanium dioxide, molecular sieve and montmorillonite.

[0045] Molecular sieves may be those known in the art, such as those selected from type A molecular sieves, type X molecular sieves, type Y molecular sieves, ZSM series, SAPO, AIPO, mordenite molecular sieves, SBA, and MCM, or a combination of two or more of these. Silica, alumina, magnesium oxide, silica-alumina, magnesium-alumina, titanium dioxide-silicon, titanium dioxide, molecular sieves, and montmorillonite may be any materials known in the art, manufactured by known methods, or any commercially available product.

[0046] In the preparation method of this invention, in step (1) above, the adhesive solvent only needs to be able to disperse the original matrix and the inorganic material. It can be an organic or inorganic substance, such as inorganic acids, inorganic bases, polycarboxylic acids, monohydric alcohols, polyhydric alcohols, polyamines, cellulose derivatives, carboxylates, etc. These adhesive solvents can be used alone or in combination as needed. The amount of adhesive solvent is not particularly limited and can be adjusted according to the total amount of the original matrix and inorganic material. Preferably, the amount of adhesive solvent is 1 to 20 parts by mass relative to 100 parts by mass of the total amount of the original matrix and inorganic material, preferably 1.2 to 10 parts by mass, and more preferably 1.5 to 5 parts by mass.

[0047] As the inorganic acid, various inorganic acids known in the art can be used, such as one or more combinations of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and perchloric acid.

[0048] The inorganic base can be an alkali metal hydroxide or an alkaline earth metal hydroxide, for example, one or more combinations of sodium hydroxide, calcium hydroxide, potassium hydroxide, magnesium hydroxide, and lithium hydroxide.

[0049] As the polycarboxylic acid, various polycarboxylic acids known in the art can be used, for example, those with 2 to 10 (preferably 3 to 6) carboxyl groups. 2-20Alkanes, for example, include oxalic acid, succinic acid, and adipic acid. As polycarboxylic acids, examples include those with one or more hydroxyl groups (e.g., 1 to 6) and 2 to 10 (preferably 3 to 6) carboxyl groups. 2-20 Alkanes, such as malic acid, tartaric acid, citric acid, and stearic acid, can also be used as polycarboxylic acids, specifically those in the C2O2 group. 2-20 Polycarboxylated alkyl (poly)amines are obtained by inserting one or more nitrogen atoms into an alkane chain, such as hypozinotriacetic acid and ethylenediaminetetraacetic acid.

[0050] As the monohydric alcohol, various monohydric alcohols known in the art can be used, such as C16 alcohols with one hydroxyl group. 1-20 Alkanes, for example, include methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol.

[0051] As the polyol, various polyols known in the art can be used, such as those with 2 to 10 (preferably 3 to 6) hydroxyl groups. 2-20 Alkanes, such as ethylene glycol, diethylene glycol, propylene glycol, glycerol, pentaerythritol, or polymers of such polyols, such as polyethylene glycol, polyvinyl alcohol, etc., or may be those contained in the C... 2-20 Polyhydroxyalkyl (poly)amines are obtained by inserting one or more nitrogen atoms into an alkane chain, such as monoethanolamine and triethanolamine.

[0052] As the polyamine, various polyamines known in the art can be used, such as ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, etc.

[0053] As the cellulose derivatives mentioned above, those known in the art can be used, such as methylcellulose, hydroxymethylcellulose, hydroxymethylpropylcellulose, carboxymethylcellulose, etc.

[0054] As the carboxylate, those carboxylate salts known in the art can be used, such as magnesium stearate, sodium stearate, etc.

[0055] In step (1), the amount of water added is not particularly limited, as long as it is sufficient to disperse the original matrix and inorganic materials. Preferably, the amount of water is 20 to 120 parts by mass relative to 100 parts by mass of the total amount of the original matrix and inorganic materials. In step (1), a kneader can be used for stirring to prepare the contact body.

[0056] In step (2), the plastic mixed contact body is molded to obtain a porous adsorbent preform. The equipment and conditions for molding are not particularly limited and can be those known in the art.

[0057] In step (2), during molding, an extruder can be used for molding, preferably an extrusion device with pressure. At this time, the pressure inside the barrel reaches 0.5 to 8 MPa, preferably 1 to 6 MPa, and the extrusion temperature of the barrel is 20 to 80°C.

[0058] It can be molded into various shapes as needed, such as spheres, cubes, cuboids, cylinders, and Raschig rings. These blanks can have macroscopic channels such as circles, squares, triangles, hexagons, or rhombuses. These channels are preferably uniformly ordered, transparent honeycomb channels.

[0059] In step (3), the porous adsorbent preform is calcined to obtain a flame-retardant porous adsorbent.

[0060] The calcination temperature in step (3) is not particularly limited, but can be 200~580℃, preferably 200~550℃, and more preferably 300~550℃. The calcination time can be 1~20 hours, preferably 2~20 hours, and more preferably 4~16 hours. The calcination can be carried out in air or in an inert gas atmosphere. Examples of inert gases include nitrogen or rare gases, with nitrogen being preferred.

[0061] In the preparation method of the present invention, step (2) is an optional step. In the absence of step (2), in step (3), the plastic mixed contact body in step (1) is calcined. The calcination conditions are the same as those described above.

[0062] Before proceeding to step (3) of the present invention, heat treatment may optionally be performed, such as drying, air drying, or air drying, to remove moisture from the plastic mixed contact body in step (1) or the porous adsorbent preform in step (2). This heat treatment is performed at 20 to 150°C, preferably at 30 to 120°C, and more preferably at 50 to 100°C.

[0063] According to the present invention, in the contact step of step (1), there is no particular limitation on the contact order of the raw material components (i.e., at least one original matrix selected from attapulgite and kaolin, at least one inorganic material selected from inorganic porous solids, and adhesive solvent and water).

[0064] According to the present invention, there are no particular limitations on the manner in which the contacting step is performed in step (1), as long as sufficient mixing and contact of the raw material components can be achieved to form a uniform contact product. For example, the raw material components can be mixed (with auxiliary stirring if necessary) in any manner known in the art until uniform. In step (1), the contacting step can be performed at any temperature from 0°C to 150°C, for example at room temperature.

[0065] The present invention also provides a porous matrix comprising the flame-retardant porous adsorbent described above or the porous adsorbent prepared according to the preparation method described above. The content of the porous adsorbent relative to the mass of the porous matrix is ​​60-100% by mass, preferably 80-100% by mass, and more preferably 90-100% by mass.

[0066] The porous matrix of the present invention may also contain other porous materials, which may be inorganic or organic porous materials. Examples of inorganic porous materials include the inorganic porous solids described above. Examples of organic porous materials include olefin homopolymers or copolymers, polyvinyl alcohol or copolymers thereof, cyclodextrin, (co)polyesters, (co)polyamides, vinyl chloride homopolymers or copolymers, acrylate homopolymers or copolymers, methacrylate homopolymers or copolymers, and styrene homopolymers or copolymers, as well as partially crosslinked forms of these homopolymers or copolymers.

[0067] In one embodiment of the present invention, the surface of the organic porous solid has one or more active functional groups selected from hydroxyl, primary amino, secondary amino, sulfonic acid group, carboxyl group, amide group, N-monosubstituted amide group, sulfonamide group, N-monosubstituted sulfonamide group, mercapto, imino and hydrazide group, wherein at least one of carboxyl and hydroxyl groups is preferred.

[0068] The present invention also provides a use of a flame-retardant porous adsorbent for use in a porous matrix (preferably a porous carrier).

[0069] The present invention also provides a use of a flame-retardant porous adsorbent for the adsorption and treatment of volatile organic compounds.

[0070] In the application of this invention for the adsorption treatment of volatile organic compounds, a flame-retardant porous adsorbent is packed into a reactor, and a gas containing VOCs is introduced, with a gas hourly space velocity of 500-20000 h⁻¹. -1 The adsorption temperature is 10~100℃, and the desorption temperature is 120~400℃.

[0071] As a desorption method, the adsorbed and enriched VOCs can be desorbed by hot air of appropriate flow rate and then sent into a catalytic oxidation reactor or directly burned in the oxidation reactor. Example

[0072] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0073] In this invention, the surface area is determined by the BET specific surface area measurement method.

[0074] The pore volume was determined using the BJH (Barrett-Joyner-Halenda) method.

[0075] The most probable pore size was determined using the BJH method.

[0076] The cross-sectional area of ​​a single honeycomb macroscopic channel (also referred to as a honeycomb cell) is calculated based on its specific shape.

[0077] Specifically, when the macroscopic channels of the honeycomb are circular, square, triangular, hexagonal, or rhomboid, the cross-sectional area can be calculated using conventional area calculation methods. When the macroscopic channels of the honeycomb are irregular in shape, the longest diameter (or longest diagonal length) and the shortest diameter (or shortest diagonal length) of the shape are measured, and the cross-sectional area is calculated as: [(longest diameter (or longest diagonal length) + shortest diameter (or shortest diagonal length)) / 4] 2 ·π. Calculate the cross-sectional area of ​​10 honeycomb cells, and use their average value as the cross-sectional area of ​​a single honeycomb cell.

[0078] The methods for determining the positive pressure strength and lateral pressure strength are in accordance with the national standard method GB / T 5072-2008.

[0079] Example 1

[0080] Attapulgite clay, 13X molecular sieve, 65% nitric acid, methylcellulose, and magnesium stearate were mixed evenly in a kneader at a mass ratio of 10:1:0.02:0.2:0.001. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The honeycomb preform was then calcined at 450°C for 2 hours to obtain flame-retardant honeycomb adsorbent molded body A, with a surface area of ​​175 m². 2 ·g -1 The most probable pore size is 6 nm, and the pore volume is 0.45 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 10 mm². 2 .

[0081] Example 2

[0082] Attapulgite, kaolin, Y-type molecular sieve, 65% nitric acid, methylcellulose, and magnesium stearate were mixed evenly in a kneader at a mass ratio of 8:2:1:0.02:0.2:0.03. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The honeycomb preform was then calcined at 400°C for 2 hours to obtain flame-retardant honeycomb adsorbent molded body B, with a surface area of ​​195 m². 2 ·g -1 The most probable pore size is 5 nm, and the pore volume is 0.61 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 10 mm². 2 .

[0083] Example 3

[0084] Attapulgite, kaolin, SBA-15 molecular sieve, 65% nitric acid, methylcellulose, and magnesium stearate were mixed evenly in a kneader at a mass ratio of 7:3:2:0.02:0.2:0.03. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a preform with square honeycomb cells. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The preform was then calcined at 400°C for 2 hours to obtain flame-retardant honeycomb adsorbent molded body C, with a surface area of ​​431 m². 2 ·g -1 The most probable pore size is 7 nm, and the pore volume is 0.7 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 10 mm². 2 .

[0085] Example 4

[0086] Attapulgite, kaolin, 5A molecular sieve, 65% nitric acid, methylcellulose, and magnesium stearate were mixed evenly in a kneader at a mass ratio of 7:3:1.4:0.02:0.2:0.03. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25℃ and 5MPa to form a square honeycomb preform. The four base sides and height of the preform were 80cm and 100cm, respectively. The preform was then calcined at 350℃ for 2 hours to obtain flame-retardant honeycomb adsorbent molded body D, with a surface area of ​​209m². 2 ·g -1 The most probable pore size is 8 nm, and the pore volume is 0.45 ml·g. -1The cross-sectional area of ​​a single honeycomb cell is 30 mm². 2 .

[0087] Example 5

[0088] Attapulgite, kaolin, SAPO molecular sieve, 65% nitric acid, methylcellulose, hexamethylenediamine, and magnesium stearate were mixed evenly in a kneader at a mass ratio of 7:3:1.4:0.02:0.2:0.01:0.03. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The preform was then calcined at 280°C for 2 hours to obtain flame-retardant honeycomb adsorbent molded body E, with a surface area of ​​198 m². 2 ·g -1 The most probable pore size is 6 nm, and the pore volume is 0.33 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 28 mm². 2 .

[0089] Example 6

[0090] Kaolin, 13X molecular sieve, 65% nitric acid, methylcellulose, and magnesium stearate were mixed evenly in a kneader at a mass ratio of 10:4:0.02:0.2:0.001. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The preform was then calcined at 500°C for 2 hours to obtain the flame-retardant honeycomb adsorbent molded body F, with a surface area of ​​152 m². 2 ·g -1 The most probable pore size is 7 nm, and the pore volume is 0.28 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 28 mm². 2 .

[0091] Example 7

[0092] Attapulgite clay, silica, 65% nitric acid, hydroxymethylpropyl cellulose, and glycerol were mixed evenly in a kneader at a mass ratio of 10:4:0.02:0.2:0.001. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The preform was then calcined at 500°C for 2 hours to obtain the flame-retardant honeycomb adsorbent molded body G, with a surface area of ​​264 m². 2 ·g -1 The most probable pore size is 6.1 nm, and the pore volume is 0.64 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 10 mm². 2 .

[0093] Example 8

[0094] Attapulgite clay, alumina, 65% nitric acid, hydroxymethylpropyl cellulose, and glycerol were mixed evenly in a kneader at a mass ratio of 7:5:0.02:0.2:0.001. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The honeycomb preform was then calcined at 500°C for 3 hours to obtain the flame-retardant honeycomb adsorbent molded body H, with a surface area of ​​242 m². 2 ·g -1 The most probable pore size is 7.2 nm, and the pore volume is 0.57 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 10 mm². 2 .

[0095] Example 9

[0096] Attapulgite clay, titanium dioxide, 65% nitric acid, hydroxymethylpropyl cellulose, and glycerol were mixed evenly in a kneader at a mass ratio of 10:3:0.02:0.2:0.001. A suitable amount of water was added, and the mixture was kneaded to form a plastic composite. This composite was then loaded into an extruder and extruded at 25°C and 5 MPa to form a square honeycomb preform. The four base sides and height of the preform were 80 cm and 100 cm, respectively. The honeycomb preform was then calcined at 480°C for 10 hours to obtain flame-retardant honeycomb adsorbent molded body I, with a surface area of ​​179 m². 2 ·g -1 The most probable pore size is 7.6 nm, and the pore volume is 0.35 ml·g. -1 The cross-sectional area of ​​a single honeycomb cell is 10 mm².2 .

[0097] Example 10

[0098] The flame-retardant honeycomb adsorbents from Examples 1-9 were loaded into an adsorption tower, and a gas containing VOCs was introduced at a temperature of 40°C. The adsorbed honeycomb adsorbents were then regenerated by desorption of VOCs using hot air at 250°C and then used for adsorption again. The results are shown in Table 1.

[0099] Table 1 Adsorption-regeneration results of flame-retardant honeycomb adsorbent

[0100] Adsorbent <![CDATA[Air speed (h -1 )]]> Characteristic pollutants <![CDATA[Inlet concentration of adsorbed VOCs (mg / m 3 )]]> <![CDATA[Single adsorption VOCs outlet concentration (mg / m 3 )]]> <![CDATA[Inlet concentration of adsorbed VOCs (mg / m 3 )]]> <![CDATA[Outlet concentration of secondary adsorbed VOCs (mg / m 3 )]]> <![CDATA[Adsorption inlet concentration of VOCs (mg / m 3 )]]> <![CDATA[Outlet concentration of VOCs after ten - time adsorption (mg / m 3 )]]> A 10000 benzene 350 Not detected 350 Not detected 350 Not detected B 10000 Toluene 390 Not detected 390 Not detected 390 Not detected C 10000 methanol 400 0.05 400 0.05 400 0.05 D 10000 Acrylonitrile 375 0.04 375 0.04 375 0.04 E 10000 hexane 500 0.03 500 0.03 500 0.03 F 10000 hexane 500 0.05 500 0.05 500 0.05 G 10000 xylene 500 0.02 500 0.02 500 0.02 H 10000 xylene 500 0.04 500 0.04 500 0.04 I 10000 xylene 500 0.06 500 0.06 500 0.06

[0101] As can be seen from Table 1, the flame-retardant honeycomb adsorbent of the present invention has excellent adsorption performance for VOCs and good recyclability.

[0102] Example 11

[0103] The flame-retardant honeycomb adsorbents in Examples 1-9 were purged with 130°C steam. After 10 hours, the purging was switched to dry hot air until the weight of the adsorbent remained unchanged. The change in the strength of the adsorbent before and after purging was measured, and the results are shown in Table 2.

[0104] Table 2. Hydrothermal stability results of flame-retardant honeycomb adsorbent

[0105] Adsorbent Freshener positive pressure (MPa) Freshener lateral pressure (MPa) Water-resistant compressive strength (MPa) Water resistance lateral compressive strength (MPa) A 6.2 1.6 6.0 1.5 B 5.4 1.2 5.1 1.1 C 5.3 1.2 5.1 1.1 D 4.8 1.2 4.7 1.1 E 4.7 1.2 4.5 1.2 F 4.2 1.1 4.0 1.0 G 4.3 1.2 4.3 1.1 H 4.0 1.0 3.8 0.8 I 3.7 1.0 3.5 0.8

[0106] As can be seen from Table 2, the flame-retardant honeycomb adsorbent of the present invention has excellent mechanical strength and excellent hydrothermal stability.

[0107] Although the invention has been described in detail herein with reference to exemplary embodiments, it should be understood that the invention is not limited to the described embodiments. Other variations, modifications, and embodiments within the scope of the invention will be recognized by those skilled in the art and who have access to the teachings herein. Therefore, the invention should be broadly interpreted in accordance with the claims set forth below.

Claims

1. The use of a flame-retardant porous adsorbent for adsorbing volatile organic compounds, wherein the adsorbed volatile organic compounds are selected from benzene, toluene, methanol, acrylonitrile, hexane, and xylene. The flame-retardant porous adsorbent contains an original matrix of attapulgite and kaolin, and a molecular sieve as an inorganic material. Based on the total mass of the adsorbent, the content of the original matrix is ​​10-99.5% by mass, the content of the inorganic material is 0.5-90% by mass, and the molecular sieve is selected from one or more combinations of type A molecular sieve, type X molecular sieve, type Y molecular sieve, ZSM molecular sieve, SAPO, AIPO, mordenite molecular sieve, SBA, and MCM.

2. The use according to claim 1, wherein, The adsorbent is composed of the original matrix and the inorganic material.

3. The use according to claim 1 or 2, wherein, The BET specific surface area of ​​the adsorbent is 100~800 m². 2 ·g -1 The most probable pore size is 2~16 nm, and the pore volume is 0.15~1.2 ml·g. -1 .

4. According to claim 1 or 2, the flame-retardant porous adsorbent is molded into an adsorbent body with an appearance of spheres, cubes, cuboids, cylinders, or Raschig rings, wherein the molded body has one or more macroscopic channel structures selected from circles, squares, triangles, hexagons, or rhombuses, and the cross-sectional area of ​​a single macroscopic pore is 1 mm². 2 ~80mm 2 The hole wall thickness is 1~4mm.

5. The use according to claim 1 or 2, wherein, The adsorbent has a positive pressure strength of 2–8 MPa and a lateral pressure strength of 0.1–2 MPa.

6. The use according to claim 1 or 2, wherein it satisfies at least one of the following conditions: The content of the original matrix is ​​20-99% by mass, and the content of the inorganic material is 5-80% by mass. The adsorbent has a BET specific surface area of ​​110~800 m². 2 ·g -1 The most probable pore size is 3~14 nm, and the pore volume is 0.2~1.2 m³. 2 ·g -1 ; The adsorbent is shaped into a spherical, cubic, cuboid, cylindrical, or Raschig ring form. The form has one or more macroscopic pore structures selected from circular, square, triangular, hexagonal, or rhombic shapes, with a cross-sectional area of ​​1 mm² for each macroscopic pore. 2 ~40mm 2 The hole wall thickness is 1~2.5mm; The adsorbent has a positive pressure strength of 2–8 MPa and a lateral pressure strength of 0.1–2 MPa.

7. The use according to claim 1 or 2, wherein, The flame-retardant porous adsorbent is prepared by a method including the following steps: (1) A plastic mixed contact body is prepared by mixing and contacting an original matrix containing attapulgite and kaolin, a molecular sieve as an inorganic material, a colloidal solvent, and water; wherein, relative to the total amount of the original matrix and the inorganic material, the content of the original matrix is ​​10~99.5% by mass, and the content of the inorganic material is 0.5~90% by mass. (2) Optionally, the plastic mixed contact body is molded to obtain a porous adsorbent blank; (3) The mixed contact body of step (1) or the porous adsorbent blank of step (2) is calcined to obtain a flame-retardant porous adsorbent. The molecular sieve is selected from one or more of the following: type A molecular sieve, type X molecular sieve, type Y molecular sieve, ZSM molecular sieve, SAPO, AIPO, mordenite molecular sieve, SBA, and MCM.

8. The use according to claim 7, wherein, The adhesive solvent is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, sodium hydroxide, calcium hydroxide, potassium hydroxide, magnesium hydroxide, lithium hydroxide, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, diethylene glycol, propylene glycol, glycerol, pentaerythritol, ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, methylcellulose, hydroxymethylcellulose, hydroxymethylpropylcellulose, carboxymethylcellulose, magnesium stearate, and sodium stearate.

9. The use according to claim 7, wherein, In step (2), the molding process is carried out under a pressure of 0.5 to 8 MPa and a temperature of 20 to 80°C.

10. The use according to claim 7, wherein, The roasting temperature in step (3) is 200~580℃.

11. The use according to claim 7, further comprising, prior to step (3), a heat treatment step of the plastic mixed contact body in step (1) or the porous adsorbent preform in step (2), wherein the heat treatment temperature is 20~150°C.

12. The use according to claim 7, wherein it satisfies at least one of the following conditions: The content of the original matrix is ​​20-99% by mass, and the content of the inorganic material is 5-80% by mass. In step (2), the molding process is carried out under a pressure of 1 to 6 MPa and a temperature of 20 to 80°C; The calcination temperature in step (3) is 200~550℃; Before step (3), a heat treatment step is performed on the plastic mixed contact body in step (1) or the porous adsorbent preform in step (2), wherein the heat treatment temperature is 50~100℃.

13. The use according to claim 1, wherein, The volume hourly space velocity (VHSV) of gases containing volatile organic compounds is 500–20000 h⁻¹. -1 The adsorption temperature is 10~100℃, and the desorption temperature is 120~400℃.