Wear-resistant attapulgite honeycomb material with self-cleaning function, preparation method and application thereof

Abstract

Wear-resistant attapulgite honeycomb materials with self-cleaning functions, as well as their preparation methods and applications, belong to the fields of atmospheric pollution control and environmentally friendly materials technology. They address the existing problems of high wear rates and severe dust accumulation in titanium-based denitrification carriers under high-dust flue gases. The preparation method of the present invention comprises the following steps: first, adding attapulgite powder to an acidic solution, continuously stirring, filtering, washing, and drying to obtain pretreated attapulgite powder; then, dissolving a metal salt and a modifier in an ethanol solution and uniformly mixing them; then, ball-milling the resulting mixed solution with the pretreated attapulgite powder and pre-incubating the mixture to obtain secondary modified attapulgite powder; finally, kneading a structural additive, a molding additive, an extrusion aid, a binder, and the secondary modified attapulgite powder; extruding the resulting clay into shape, drying, and calcining it to obtain a attapulgite honeycomb material. The attapulgite honeycomb material has low cost, high mechanical strength, and dust suppression properties, and can be used as a carrier for a denitrification catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of atmospheric pollution control and environmental protection materials, and specifically relates to a wear-resistant attapulgite honeycomb material with a self-cleaning function, a preparation method and an application thereof, and especially relates to the application of the wear-resistant attapulgite honeycomb material with a self-cleaning function as a carrier of a denitrification catalyst. Background Art

[0002] Currently, most commonly used industrial denitrification honeycomb catalysts are based on titanium dioxide (over 85%), formed by extrusion or coating, for the control of nitrogen oxides. However, titanium-based catalysts are prone to wear and dust accumulation when used in high-dust environments, severely limiting their service life and catalytic performance. Furthermore, titanium dioxide is expensive, and its production is highly polluting, requires a long process, and consumes a lot of energy. Attapulgite, a readily available, natural, green mineral, offers advantages such as a unique nanoporous structure, a large specific surface area, strong ion exchange capacity, and high mechanical strength after sintering, making it a potential low-cost alternative catalyst support. However, natural attapulgite suffers from numerous impurities, wide grade fluctuations, and a limited number of acidic sites and functional groups. Therefore, modifying and manipulating attapulgite to achieve both high mechanical strength and dust repellency remains a key technical challenge.

[0003] Patent CN115888634B discloses a high-strength, water-resistant adsorbent and its preparation method. This method uses two different types of attapulgite as the main raw materials, supplemented with glycerin, a pore-enlarging agent, and an organic binder. The mixture is kneaded, kneaded, and formed, then microwave-dried and calcined to finalize the shape. Finally, the honeycomb material is immersed in a solution containing a hydrophobic modifier and vacuum-dried to produce a high-strength, water-resistant attapulgite honeycomb adsorbent. While this technology improves the mechanical strength and hydrophobic energy absorption of the honeycomb material to a certain extent, it still suffers from issues such as insufficient mechanical strength and a lack of investigation into dust adsorption performance. Summary of the Invention

[0004] In order to solve the drawbacks of high wear rate and serious dust accumulation of titanium-based denitrification carriers in high-dust flue gas in the prior art, the present invention provides a wear-resistant attapulgite honeycomb material with self-cleaning function and its preparation method and application. The attapulgite honeycomb material has low cost, high mechanical strength and dust suppression performance, and can be used as a carrier of denitrification catalyst.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows.

[0006] In a first aspect, the present invention provides a method for preparing a wear-resistant attapulgite honeycomb material with a self-cleaning function, comprising the following steps:

[0007] Step 1: adding attapulgite powder to an acidic solution, stirring continuously, filtering, washing until the pH value of the filtrate is 6-7, and drying to obtain pretreated attapulgite powder;

[0008] The acidic solution is a mixed solution of a monoprotic acid solution, a polyprotic acid solution and an ammonium salt solution;

[0009] Step 2: dissolving the metal salt and the modifier in an ethanol solution, mixing them evenly to obtain a mixed solution, and ball-milling the pretreated attapulgite powder and the mixed solution under an inert atmosphere, keeping the mixture warm, to obtain a secondary modified attapulgite powder;

[0010] Step three, kneading the structural additive, molding additive, extrusion aid, binder and secondary modified attapulgite powder into mud, extruding the obtained mud into shape, drying and calcining to obtain a wear-resistant attapulgite honeycomb material with self-cleaning function.

[0011] Preferably, in step 1, the mass ratio of the attapulgite powder to the acidic solution is 0.2-0.5:1.

[0012] Preferably, in step 1, the concentration of the monoprotic acid solution is 1.0-3.0 mol / L, the concentration of the polyprotic acid solution is 0.5-2.0 mol / L, the concentration of the ammonium salt solution is 0.1-2.0 mol / L, and the mass ratio of the monoprotic acid solution, the polyprotic acid solution and the ammonium salt solution is 0.1-0.5:0.2-0.6:0.1-0.4.

[0013] Preferably, in step 1, the monoprotic acid is hydrochloric acid, nitric acid, hydrofluoric acid or acetic acid.

[0014] Preferably, in step 1, the polyacid is sulfuric acid, tartaric acid, phosphoric acid or malonic acid.

[0015] Preferably, in step 1, the ammonium salt is ammonium carbonate, ammonium sulfate, ammonium chloride or ammonium fluoride.

[0016] Preferably, in step 1, the temperature for continuous stirring is 20° C. to 60° C., and the time for continuous stirring is 2 to 4 hours.

[0017] Preferably, in step 2, the metal salt is ferric nitrate, zirconium nitrate, chromium nitrate or cerium nitrate, and the mass ratio of the metal salt (calculated as oxide mass) to the pretreated attapulgite powder is 0.05-0.1:1.

[0018] Preferably, in step 2, the modifier is methylphenyl silicone resin, lauryl phosphate or aluminate coupling agent (DL-411), and the mass ratio of the modifier to the pretreated attapulgite powder is 0.01-0.05:1.

[0019] Preferably, in step 2, the mass concentration of the ethanol solution is 1% to 5%, and the mass ratio of the ethanol solution to the pretreated attapulgite powder is 0.5 to 1:1.

[0020] Preferably, in step 2, the mixing is carried out by ultrasound, and the ultrasound time is 20 to 120 minutes.

[0021] Preferably, in step 2, the inert atmosphere is nitrogen.

[0022] Preferably, in step 2, the ball milling time is 4 to 8 hours, the insulation temperature is 80 to 100° C., the insulation time is 2 to 6 hours, and the temperature is increased to the insulation temperature at a heating rate of 5° C. / min.

[0023] Preferably, in step three, the structural additive is one or more of silicon carbide nanofiber, glass fiber, and aluminum silicate ceramic fiber, and the mass ratio of the structural additive to the secondary modified attapulgite powder is 0.05-0.1:1.

[0024] Preferably, in step three, the molding aid is one or more of lactic acid, polyacrylic acid, and polysorbate, and the mass ratio of the structural aid to the secondary modified attapulgite powder is 0.01-0.05:1.

[0025] Preferably, in step three, the extrusion aid is one or more of ethylene glycol, glycerol, and triphosphate, and the mass ratio of the extrusion aid to the secondary modified attapulgite powder is 0.01-0.05:1.

[0026] Preferably, in step three, the binder is one or more of carboxymethyl cellulose, polyacrylamide, and polyethylene oxide, and the mass ratio of the binder to the secondary modified attapulgite powder is 0.05-0.2:1.

[0027] Preferably, in step three, the clay kneading is repeated 3 to 5 times.

[0028] Preferably, in step three, the drying temperature is 30-90° C., and the drying time is 4-6 days.

[0029] Preferably, in step three, the calcination temperature is 500-600° C., and the calcination time is 2-6 hours.

[0030] In a second aspect, the present invention provides a wear-resistant attapulgite honeycomb material with a self-cleaning function prepared by the above preparation method.

[0031] In a third aspect, the present invention provides the use of the aforementioned wear-resistant attapulgite honeycomb material with a self-cleaning function as a carrier of a denitration catalyst.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention discloses a method for preparing a wear-resistant attapulgite honeycomb material with a self-cleaning function. The attapulgite is pretreated with a mixed solution of a monoprotic acid solution, a polyprotic acid solution, and an ammonium salt solution, thereby removing impurities, opening up pores, and expanding the pores. The mixed solution dissolves and removes impurities within the attapulgite, such as calcite, dolomite, quartz, and some organic matter, significantly improving the attapulgite's quality. Furthermore, the mixed solution dredges and etches the pore structure of the attapulgite, increasing its specific surface area, pore volume, and pore diameter.

[0034] The preparation method of the wear-resistant attapulgite honeycomb material with self-cleaning function of the present invention introduces metal salts and modifiers to perform ion exchange on some cations of the attapulgite, thereby improving the redox performance of the attapulgite and reducing the dust adhesion ability, while increasing the mechanical strength of the molding.

[0035] The preparation method of the wear-resistant attapulgite honeycomb material with self-cleaning function of the present invention, wherein various additives are added during the molding process, are conducive to the rapid extrusion molding of the honeycomb, with a short molding cycle and a high qualified rate of finished products; the mechanical strength of the molded attapulgite can be further improved, and the influence on the specific surface area is small, and the material can be used as a carrier of a denitrification catalyst.

[0036] The attapulgite honeycomb material prepared by the invention has excellent dust suppression performance and high mechanical strength, and is low in cost, and can be used as a carrier of a denitration catalyst. DETAILED DESCRIPTION

[0037] To facilitate understanding of the present invention, various exemplary embodiments of the present invention are now described in detail. This description should not be considered as a specific limitation of the present invention, but should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0038] The method for preparing the wear-resistant attapulgite honeycomb material with a self-cleaning function of the present invention comprises the following steps:

[0039] Step 1: adding attapulgite powder to an acidic solution, stirring continuously, filtering, washing until the pH value of the filtrate is 6-7, and drying to obtain pretreated attapulgite powder;

[0040] Step 2: dissolving the metal salt and the modifier in an ethanol solution, mixing them evenly to obtain a mixed solution, and ball-milling the pretreated attapulgite powder and the mixed solution under an inert atmosphere, keeping the mixture warm, to obtain a secondary modified attapulgite powder;

[0041] Step three, kneading the structural additive, molding additive, extrusion aid, binder and secondary modified attapulgite powder into mud, extruding the obtained mud into shape, drying and calcining to obtain a wear-resistant attapulgite honeycomb material with self-cleaning function.

[0042] In step one of the present invention, the acidic solution is a mixed solution of a monoprotic acid solution, a polyprotic acid solution and an ammonium salt solution, and the acidic solution realizes the effect of removing impurities, sparse pores and expanding pores on attapulgite. Preferably, the monoprotic acid is hydrochloric acid, nitric acid, hydrofluoric acid or acetic acid, and the concentration of the monoprotic acid solution is 1.0 to 3.0 mol / L, such as using 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L in some embodiments, but not limited thereto. Preferably, the polyprotic acid is sulfuric acid, tartaric acid, phosphoric acid or malonic acid, and the concentration of the polyprotic acid solution is 0.5 to 2.0 mol / L, such as using 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L in some embodiments, but not limited thereto. Preferably, the ammonium salt is ammonium carbonate, ammonium sulfate, ammonium chloride or ammonium fluoride, and the concentration of the ammonium salt solution is 0.1 to 2.0 mol / L, such as in some embodiments using 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, but not limited thereto. Preferably, the mass ratio of the monoprotic acid solution, the polyprotic acid solution and the ammonium salt solution is 0.1 to 0.5:0.2 to 0.6:0.1 to 0.4, such as in some embodiments using 0.5:0.4:0.1, 0.4:0.3:0.3, 0.3:0.5:0.1, 0.1:0.5:0.4, but not limited thereto.

[0043] In step 1 of the present invention, the mass ratio of attapulgite powder to acidic solution is preferably 0.2 to 0.5:1. For example, in some embodiments, the mass ratio is 0.2:1, 0.3:1, 0.4:1, or 0.5:1, but is not limited thereto.

[0044] In step 1 of the present invention, the temperature for continuous stirring is preferably 20° C. to 60° C., and the continuous stirring time is 2 to 4 hours. Water is usually used for washing.

[0045] In step 2 of the present invention, the metal salt is preferably a metal nitrate, such as ferric nitrate, zirconium nitrate, chromium nitrate, or cerium nitrate, and the mass ratio of the metal salt (calculated as the mass of the metal oxide) to the pretreated attapulgite powder is 0.05 to 0.1:1. For example, in some embodiments, the ratio is 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, or 0.1:1, but is not limited thereto.

[0046] In step 2 of the present invention, the modifier is preferably methylphenyl silicone resin, lauryl phosphate, or aluminate coupling agent (DL-411), and the mass ratio of the modifier to the pretreated attapulgite powder is 0.01 to 0.05:1. For example, in some embodiments, the mass ratio is 0.01:1, 0.02:1, 0.03:1, 0.04:1, or 0.05:1, but is not limited thereto.

[0047] In step 2 of the present invention, the mass concentration of the ethanol solution is preferably 1% to 5%, such as, but not limited to, 1%, 2%, 3%, 4%, or 5% in some embodiments. The mass ratio of the ethanol solution to the pretreated attapulgite powder is 0.5 to 1:1, such as, but not limited to, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1 in some embodiments.

[0048] In step 2 of the present invention, the preferred method for uniform mixing is ultrasound, and the ultrasound time is 20 to 120 minutes.

[0049] In step 2 of the present invention, the preferred inert atmosphere is nitrogen.

[0050] In step 2 of the present invention, the ball milling time is preferably 4 to 8 hours, the holding temperature is 80 to 100° C., the holding time is 2 to 6 hours, and the temperature is increased to the holding temperature at a heating rate of 5° C. / min.

[0051] In step three of the present invention, the structural additive is preferably one or more of silicon carbide nanofibers, glass fibers, and aluminum silicate ceramic fibers, and the mass ratio of the structural additive to the secondary modified attapulgite powder is 0.05-0.1:1.

[0052] In step 3 of the present invention, the molding aid is preferably one or more of lactic acid, polyacrylic acid, and polysorbate, and the mass ratio of the structural aid to the secondary modified attapulgite powder is 0.01 to 0.05:1. For example, in some embodiments, the ratio is 0.01:1, 0.02:1, 0.03:1, 0.04:1, or 0.05:1, but is not limited thereto.

[0053] In step 3 of the present invention, the extrusion aid is preferably one or more of ethylene glycol, glycerol, and triphosphate, and the mass ratio of the extrusion aid to the secondary modified attapulgite powder is 0.01 to 0.05:1. For example, in some embodiments, the ratio is 0.01:1, 0.02:1, 0.03:1, 0.04:1, or 0.05:1, but is not limited thereto.

[0054] In step 3 of the present invention, the binder is preferably one or more of carboxymethyl cellulose, polyacrylamide, and polyethylene oxide, and the mass ratio of the binder to the secondary modified attapulgite powder is 0.05 to 0.2:1. For example, in some embodiments, the ratio is 0.05:1, 0.1:1, 0.15:1, or 0.2:1, but is not limited thereto.

[0055] In step 3 of the present invention, preferably, the clay kneading is repeated 3 to 5 times.

[0056] In step 3 of the present invention, the drying temperature is preferably 30-90° C., and the drying time is 4-6 days.

[0057] In step 3 of the present invention, the calcination temperature is preferably 500-600° C., and the calcination time is preferably 2-6 hours.

[0058] The wear-resistant attapulgite honeycomb material with self-cleaning function prepared by the preparation method of the present invention can be used as a carrier of a denitration catalyst. The specific application method is not particularly limited, and reference can be made to the application method of the denitration catalyst carrier in the prior art.

[0059] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the following embodiments and comparative examples.

[0060] In the following examples and comparative examples, any processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, and equipment used in the following examples and comparative examples are commercially available. It should be noted that the solvent used in the solutions in the examples and comparative examples is water, and "hydrochloric acid solution" refers to "aqueous hydrochloric acid solution."

[0061] Example 1

[0062] Step 1: Mix 12.5 kg of 1.0 mol / L hydrochloric acid solution, 10 kg of 0.5 mol / L sulfuric acid solution, and 2.5 kg of 0.1 mol / L ammonium carbonate solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 20°C for 4 hours. Then filter and wash the filtrate until the pH value reaches 7. Dry the mixture to obtain the pretreated attapulgite powder.

[0063] Step 2: dissolving 0.2 kg of ferric nitrate and 0.04 kg of methylphenyl silicone resin in 2 kg of 1% mass concentration ethanol solution, and ultrasonicating for 20 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling under nitrogen protection for 4 hours, and heating the ball-milled powder to 80 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 6 hours to obtain a secondary modified attapulgite powder;

[0064] Step three, add 0.2 kg of silicon carbide nanofibers, 0.04 kg of lactic acid, 0.04 kg of ethylene glycol, 0.2 kg of carboxymethyl cellulose and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading three times, then extrude the mud into shape through a molding extruder, and dry the molded product at 40°C for 6 days; the dried honeycomb carrier is calcined at 500°C for 6 hours to obtain a wear-resistant attapulgite honeycomb material with self-cleaning function.

[0065] Example 2

[0066] Step 1: 6.4 kg of 1.5 mol / L nitric acid solution, 4.8 kg of 1 mol / L tartaric acid solution, and 4.8 kg of 0.5 mol / L ammonium sulfate solution are uniformly stirred to obtain an acidic solution. 5 kg of attapulgite powder is added to the acidic solution and stirred continuously at 30°C for 3 hours. The mixture is then filtered, washed until the filtrate reaches a pH of 7, and dried to obtain pretreated attapulgite powder.

[0067] Step 2: dissolving 0.28 kg of zirconium nitrate and 0.08 kg of lauryl phosphate in 2.8 kg of 3% mass concentration ethanol solution, and ultrasonicating for 30 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling under nitrogen protection for 5 hours, and heating the ball-milled powder to 90 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 5 hours to obtain a secondary modified attapulgite powder;

[0068] Step three, add 0.24 kg of glass fiber, 0.08 kg of polyacrylic acid, 0.12 kg of glycerol, 0.32 kg of polyacrylamide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 4 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 50°C for 5 days; the dried honeycomb carrier is calcined at 550°C for 5 hours to obtain a wear-resistant attapulgite honeycomb material with self-cleaning function.

[0069] Example 3

[0070] Step 1: Mix 3.75 kg of 2 mol / L hydrofluoric acid solution, 7.5 kg of 1.5 mol / L phosphoric acid solution, and 1.25 kg of 1 mol / L ammonium chloride solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 50°C for 2.5 hours. Then, filter and wash the filtrate until the pH value reaches 7, and dry it to obtain the pretreated attapulgite powder.

[0071] Step 2: dissolving 0.32 kg of chromium nitrate and 0.12 kg of lauryl phosphate in 3.2 kg of 4% mass concentration ethanol solution, and ultrasonicating for 80 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling under nitrogen protection for 6 hours, heating the ball-milled powder to 100 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 2 hours to obtain a secondary modified attapulgite powder;

[0072] Step three, add 0.32 kg of aluminum silicate ceramic fiber, 0.16 kg of lactic acid, 0.16 kg of triphosphate, 0.4 kg of polyethylene oxide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 4 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 70°C for 4 days; the dried honeycomb carrier is calcined at 600°C for 2 hours to obtain a wear-resistant attapulgite honeycomb material with self-cleaning function.

[0073] Example 4

[0074] Step 1: Mix 1 kg of 3 mol / L acetic acid solution, 5 kg of 2 mol / L malonic acid solution, and 4 kg of 2 mol / L ammonium fluoride solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 60°C for 2 hours. Then, filter and wash the filtrate until the pH value reaches 7, and dry it to obtain pretreated attapulgite powder.

[0075] Step 2: dissolving 0.4 kg of cerium nitrate and 0.2 kg of DL-411 in 4 kg of 5% mass concentration ethanol solution, and ultrasonicating for 120 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling for 8 hours under nitrogen protection, heating the ball-milled powder to 100 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 2 hours to obtain a secondary modified attapulgite powder;

[0076] Step three, add 0.4 kg of silicon carbide nanofibers, 0.2 kg of lactic acid, 0.2 kg of glycerol, 0.8 kg of polyethylene oxide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 5 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 90°C for 4 days; the dried honeycomb carrier is calcined at 600°C for 2 hours to obtain a wear-resistant attapulgite honeycomb material with self-cleaning function.

[0077] Comparative Example 1

[0078] In Comparative Example 1, the step of adding ammonium salt solution in step 1 of Example 4 was deleted, and other processes remained unchanged. The specific steps were as follows:

[0079] Step 1: Mix 1 kg of 3 mol / L acetic acid solution and 5 kg of 2 mol / L malonic acid solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 60°C for 2 hours. Then, filter and wash the filtrate until the pH of the filtrate reaches 7, and dry it to obtain pretreated attapulgite powder.

[0080] Step 2: dissolving 0.4 kg of cerium nitrate and 0.2 kg of DL-411 in 4 kg of 5% mass concentration ethanol solution, and ultrasonicating for 120 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling for 8 hours under nitrogen protection, heating the ball-milled powder to 100 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 2 hours to obtain a secondary modified attapulgite powder;

[0081] Step three, add 0.4 kg of silicon carbide nanofibers, 0.2 kg of lactic acid, 0.2 kg of glycerol, 0.8 kg of polyethylene oxide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 5 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 90°C for 4 days; the dried honeycomb carrier is calcined at 600°C for 2 hours to obtain the attapulgite honeycomb material.

[0082] Comparative Example 2

[0083] In Comparative Example 2, the nitrate addition process in step 2 of Example 4 was deleted, and other processes remained unchanged. The specific steps are as follows:

[0084] Step 1: Mix 1 kg of 3 mol / L acetic acid solution, 5 kg of 2 mol / L malonic acid solution, and 4 kg of 2 mol / L ammonium fluoride solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 60°C for 2 hours. Then, filter and wash the filtrate until the pH value reaches 7, and dry it to obtain pretreated attapulgite powder.

[0085] Step 2: dissolving 0.2 kg of DL-411 into 4 kg of 5% mass concentration ethanol solution, and ultrasonicating for 120 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the mixed solution into a planetary ball mill and ball milling under nitrogen for 8 hours, heating the ball-milled powder at 5 ° C / min to 100 ° C under nitrogen protection, and keeping it warm for 2 hours to obtain a secondary modified attapulgite powder;

[0086] Step three, add 0.4 kg of silicon carbide nanofibers, 0.2 kg of lactic acid, 0.2 kg of glycerol, 0.8 kg of polyethylene oxide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 5 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 90°C for 4 days; the dried honeycomb carrier is calcined at 600°C for 2 hours to obtain the attapulgite honeycomb material.

[0087] Comparative Example 3

[0088] In Comparative Example 3, the step of adding the modifier in step 2 of Example 4 was deleted, and the other processes remained unchanged. The specific steps are as follows:

[0089] Step 1: Mix 1 kg of 3 mol / L acetic acid solution, 5 kg of 2 mol / L malonic acid solution, and 4 kg of 2 mol / L ammonium fluoride solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 60°C for 2 hours. Then, filter and wash the filtrate until the pH value reaches 7, and dry it to obtain pretreated attapulgite powder.

[0090] Step 2: dissolving 0.4 kg of cerium nitrate into 4 kg of 5% mass concentration ethanol solution, and ultrasonicating for 120 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling for 8 hours under nitrogen protection, heating the ball-milled powder to 100 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 2 hours to obtain a secondary modified attapulgite powder;

[0091] Step three, add 0.4 kg of silicon carbide nanofibers, 0.2 kg of lactic acid, 0.2 kg of glycerol, 0.8 kg of polyethylene oxide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 5 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 90°C for 4 days; the dried honeycomb carrier is calcined at 600°C for 2 hours to obtain the attapulgite honeycomb material.

[0092] Comparative Example 4

[0093] In Comparative Example 4, the step of adding the structural additive in step 3 of Example 4 was deleted, and the other processes remained unchanged. The specific steps are as follows:

[0094] Step 1: Mix 1 kg of 3 mol / L acetic acid solution, 5 kg of 2 mol / L malonic acid solution, and 4 kg of 2 mol / L ammonium fluoride solution to obtain an acidic solution. Add 5 kg of attapulgite powder to the acidic solution and stir continuously at 60°C for 2 hours. Then, filter and wash the filtrate until the pH value reaches 7, and dry it to obtain pretreated attapulgite powder.

[0095] Step 2: dissolving 0.4 kg of cerium nitrate and 0.2 kg of DL-411 in 4 kg of 5% mass concentration ethanol solution, and ultrasonicating for 120 minutes to obtain a mixed solution; adding 4 kg of the pretreated attapulgite powder obtained in step 1 and the above mixed solution to a planetary ball mill and ball milling for 8 hours under nitrogen protection, heating the ball-milled powder to 100 ° C at 5 ° C / min under nitrogen protection, and keeping it warm for 2 hours to obtain a secondary modified attapulgite powder;

[0096] Step three, add 0.2 kg of lactic acid, 0.2 kg of glycerol, 0.8 kg of polyethylene oxide and 4 kg of the secondary modified attapulgite powder obtained in step two into a vacuum mud kneading machine and repeat the mud kneading 5 times, then extrude the mud into shape through a molding extruder, and dry the molded product at 90°C for 4 days; the dried honeycomb carrier is calcined at 600°C for 2 hours to obtain the attapulgite honeycomb material.

[0097] The mechanical strength and dust adsorption performance of the attapulgite honeycomb materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were tested. The test results are shown in Table 1.

[0098] Mechanical strength test: According to GB / T5072-2008 standard, the axial compressive strength and radial compressive strength of the attapulgite honeycomb material sample were measured using a compressive strength tester.

[0099] Dust Adsorption Performance Test: The carrier and device were prepared according to the wear rate determination section of "GB / T 31587-2015 Honeycomb Flue Gas Denitrification Catalyst." Using 300-mesh calcium powder, the continuous scouring of the attapulgite honeycomb surface by dust carried by airflow in industrial or natural environments was simulated. The amount of dust remaining on the attapulgite honeycomb surface was measured using the following formula to evaluate its dust suppression performance. The lower the residual amount, the greater the attapulgite honeycomb surface's resistance to dust adhesion.

[0100]

[0101] Where, : Initial quality of clean attapulgite honeycomb material, : The total mass (including sediment) of attapulgite honeycomb material after use (before cleaning), : Residual mass on the surface of attapulgite honeycomb material after cleaning.

[0102] Table 1 Performance test results of attapulgite honeycomb materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4

[0103]

[0104] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the embodiments. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all embodiments here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a wear-resistant attapulgite honeycomb material with a self-cleaning function, characterized in that: The following steps are involved: Step 1: adding attapulgite powder to an acidic solution, continuously stirring, filtering, washing until the pH value of the filtrate is 6-7, and drying to obtain pretreated attapulgite powder; The acidic solution is a mixed solution of a monoprotic acid solution, a polyprotic acid solution and an ammonium salt solution; Step 2: dissolving the metal salt and the modifier in an ethanol solution, mixing them evenly to obtain a mixed solution, and ball-milling the pretreated attapulgite powder and the mixed solution under an inert atmosphere, keeping the mixture warm, to obtain a secondary modified attapulgite powder; Step three, the structural additives, molding aids, extrusion aids, binders and secondary modified attapulgite powder slurry training, the resulting mud extrusion molding, drying, calcining, to obtain a wear-resistant attapulgite honeycomb material having a self-cleaning function; Wherein, in step 1, the monoprotic acid is hydrochloric acid, nitric acid, hydrofluoric acid or acetic acid, and the concentration of the monoprotic acid solution is 1.0 to 3.0 mol / L; the polyprotic acid is sulfuric acid, tartaric acid, phosphoric acid or malonic acid, and the concentration of the polyprotic acid solution is 0.5 to 2.0 mol / L; the ammonium salt is ammonium carbonate, ammonium sulfate, ammonium chloride or ammonium fluoride, and the concentration of the ammonium salt solution is 0.1 to 2.0 mol / L; the mass ratio of the monoprotic acid solution, the polyprotic acid solution and the ammonium salt solution is 0.1 to 0.5:0.2 to 0.6:0.1 to 0.4; In step 2, the metal salt is ferric nitrate, zirconium nitrate, chromium nitrate or cerium nitrate, and the mass ratio of the metal salt to the pretreated attapulgite powder is 0.05 to 0.1:1, and the mass of the metal salt is calculated based on the mass of the oxide; the modifier is methylphenyl silicone resin, lauryl phosphate or aluminate coupling agent, and the mass ratio of the modifier to the pretreated attapulgite powder is 0.01 to 0.05:

1.

2. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step 1, the mass ratio of the attapulgite powder to the acidic solution is 0.2 to 0.5:

1.

3. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step 1, the temperature for continuous stirring is 20° C. to 60° C., and the time for continuous stirring is 2 to 4 hours.

4. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step 2, the mass concentration of the ethanol solution is 1% to 5%, and the mass ratio of the ethanol solution to the pretreated attapulgite powder is 0.5 to 1:

1.

5. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step 2, the mixing method is ultrasonication, and the ultrasonication time is 20 to 120 minutes; The inert atmosphere is nitrogen; The ball milling time is 4 to 8 hours; The insulation temperature is 80-100° C., the insulation time is 2-6 hours, and the temperature is increased to the insulation temperature at a heating rate of 5° C. / min.

6. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step 3, the structural additive is one or more of silicon carbide nanofiber, glass fiber, and aluminum silicate ceramic fiber, and the mass ratio of the structural additive to the secondary modified attapulgite powder is 0.05 to 0.1:1; The molding aid is one or more of lactic acid, polyacrylic acid, and polysorbate, and the mass ratio of the structural aid to the secondary modified attapulgite powder is 0.01 to 0.05:1; The extrusion aid is one or more of ethylene glycol, glycerol, and triphosphate, and the mass ratio of the extrusion aid to the secondary modified attapulgite powder is 0.01 to 0.05:1; The binder is one or more of carboxymethyl cellulose, polyacrylamide, and polyethylene oxide, and the mass ratio of the binder to the secondary modified attapulgite powder is 0.05-0.2:

1.

7. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step three, the clay kneading is repeated 3 to 5 times.

8. The method for preparing the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 1, characterized in that: In step 3, the drying temperature is 30-90° C. and the drying time is 4-6 days; The calcination temperature is 500-600° C., and the calcination time is 2-6 hours. 9 . The wear-resistant attapulgite honeycomb material with self-cleaning function prepared by the preparation method according to claim 1 .

10. Use of the wear-resistant attapulgite honeycomb material with self-cleaning function according to claim 9 as a carrier of a denitration catalyst.

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