Granular polymer denitration agent and preparation method thereof

Abstract

The invention relates to the technical field of denitration agents, and discloses a granular polymer denitration agent and a preparation method thereof, the denitration agent comprises 18-30 parts by weight of melamine-urea-formaldehyde resin and 70-82 parts by weight of a manganese-based molecular sieve catalyst; a polyethyleneimine molecular chain introduced into the molecular sieve is used as an adsorption site, manganese and molybdenum ions are complexed and adsorbed, manganese and molybdenum are uniformly adsorbed on the surface of the SBA-15 molecular sieve, and manganese-molybdenum catalytic active centers are uniformly distributed on the surface of a molecular sieve catalyst through high-temperature calcination, so that more manganese-molybdenum denitration catalytic centers are exposed, and the denitration efficiency of the SBA-15 molecular sieve is improved. And finally, compounding with melamine-urea-formaldehyde resin to obtain the granular high-molecular denitration agent which shows higher NO conversion rate catalysis and denitration performance.

Description

Technical Field

[0001] The invention relates to the technical field of denitrification agents, in particular to a granular polymer denitrification agent and a preparation method thereof. Background Art

[0002] Polymer non-catalytic reduction technology is a new type of furnace denitrification technology. In the actual operation process, the polymer solid denitrification agent is directly added to the furnace equipment for denitrification reaction. It has the advantages of low cost, simple process, high denitrification rate, wide operating temperature range, etc. It has broad application prospects in the fields of boiler flue gas purification. Such as polyacrylamide, polyethylene, urea-formaldehyde resin and other polymer resin denitrification agents. Combining polymer resin denitrification agents with metal catalysts can obtain denitrification catalysts with better catalytic performance.

[0003] Molecular sieve is an inorganic porous material with strong high temperature resistance, stable chemical properties, large specific surface area, and is an excellent catalyst carrier. The molecular sieve is loaded with catalysts such as manganese, copper, molybdenum, and iridium, and the resulting catalyst has broad application prospects in denitrification, desulfurization, catalytic oxidation, etc. However, these metal catalysts have poor dispersion in molecular sieves and are prone to agglomeration, resulting in insufficient exposure of catalytic neutrality and affecting catalytic activity. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a granular polymer denitrification agent with a high denitrification rate.

[0005] The technical solution provided by the present invention is: a granular polymer denitrification agent, comprising 18-30 parts by weight of melamine-urea-formaldehyde resin and 70-82 parts by weight of manganese-based molecular sieve catalyst.

[0006] The preparation method of the manganese-based molecular sieve catalyst comprises:

[0007] Step (1), adding water and epoxy SBA-15 molecular sieve into a reaction container, dispersing by ultrasonication, then adding polyethyleneimine, filtering after reaction, washing with water, and drying to obtain polyethyleneimine modified molecular sieve.

[0008] Step (2), adding water, ethanol, polyethyleneimine modified molecular sieve in a mass ratio of 100:(5-25):(0.3-1), manganese source, and molybdenum source into a reaction container, stirring and drying the solution to remove the solvent, placing the product in a tubular furnace, heating to a calcination temperature, heat preservation treatment, and cooling to obtain a manganese-based molecular sieve catalyst.

[0009] Preferably, in step (1), the mass ratio of epoxy SBA-15 molecular sieve to polyethyleneimine is 100:(20-50).

[0010] Preferably, in (1), the reaction temperature is 50-80°C and the reaction time is 3-8h.

[0011] Preferably, in step (2), the manganese source is at least one of manganese nitrate, manganese sulfate, manganese chloride and manganese acetylacetonate.

[0012] Preferably, in step (2), the molybdenum source includes at least one of molybdenum trichloride and molybdenum acetylacetonate.

[0013] Preferably, in step (2), the stirring temperature is 20-40° C. and the stirring time is 3-6 h.

[0014] Preferably, in step (2), the heating rate is 5-10°C / min, the calcination temperature is 450-600°C, and the insulation time is 4-6h.

[0015] Preferably, in step (2), the preparation method of epoxy SBA-15 molecular sieve comprises: adding water and poloxamer template agent to a reaction container, stirring and dissolving, adding concentrated hydrochloric acid, heating to 40-45° C., adding tetraethyl orthosilicate, stirring for 30-60 min, and then adding γ-glycidyloxypropyltrimethoxysilane, and then transferring the solution to a hydrothermal reactor, reacting at 100-110° C. for 18-24 h, filtering, washing with ethanol to remove the template agent, and drying to obtain epoxy SBA-15 molecular sieve.

[0016] Preferably, the mass ratio of poloxamer template agent, tetraethyl orthosilicate, and γ-glycidyloxypropyltrimethoxysilane is (50-60):100:(6-12).

[0017] Preferably, the preparation method of the granular polymer denitrification agent comprises: adding a manganese-based molecular sieve catalyst and a melamine-urea-formaldehyde resin into a mixer, mixing and discharging the materials to obtain the granular polymer denitrification agent.

[0018] Technical effect: The present invention uses tetraethyl orthosilicate as the precursor of SBA-15 molecular sieve, adds γ-glycidyloxypropyltrimethoxysilane as a modifier, and obtains an SBA-15 molecular sieve containing epoxy groups on the surface. Then the epoxy groups react with part of the amino groups of polyethyleneimine to obtain a polyethyleneimine grafted modified molecular sieve. The introduced polyethyleneimine molecular chain is used as an adsorption site to perform complex adsorption on manganese and molybdenum ions, and manganese and molybdenum are uniformly adsorbed on the surface of the SBA-15 molecular sieve. After high-temperature calcination, the manganese and molybdenum catalytic active centers are evenly distributed on the surface of the molecular sieve catalyst, thereby exposing more manganese and molybdenum denitrification catalytic centers, and finally compounded with melamine-urea-formaldehyde resin to obtain a granular polymer denitrification agent, which exhibits higher catalytic NO conversion rate and denitrification performance. DETAILED DESCRIPTION

[0019] In order to understand the technical features and contents of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described here.

[0020] Add 800 mL of an aqueous solution containing 4.5 mol formaldehyde to a reaction vessel equipped with a condenser, add sodium hydroxide to adjust the pH to 8, then add 0.12 mol urea, heat to 95°C, react for 40 min, add formic acid to adjust the pH to 4.5, then add 0.28 mol urea, react for 40 min, add sodium hydroxide to adjust the pH to 9.5, add 0.1 mol melamine, react for 60 min, cool the material, dry and remove water to obtain melamine-urea-formaldehyde resin.

[0021] Poloxamer model F127, Shaanxi Tangyao Biotechnology Co., Ltd.

[0022] Polyethyleneimine model UN318, Shanghai Youen Chemical Co., Ltd.

[0023] Example 1

[0024] (1) Add 150 mL of water and 5.2 g of poloxamer template agent to a reaction container, stir to dissolve, add 32 mL of concentrated hydrochloric acid, heat to 40° C., add 10 g of ethyl orthosilicate, stir for 30 min, then add 1.2 g of γ-glycidyloxypropyltrimethoxysilane, and then transfer the solution to a hydrothermal reactor, react at 110° C. for 18 h, filter, wash with ethanol to remove the template agent, and dry to obtain an epoxy SBA-15 molecular sieve.

[0025] (2) Add 400 mL of water and 15 g of epoxy SBA-15 molecular sieve into a reaction container, disperse by ultrasound, then add 5.8 g of polyethyleneimine, heat to 80° C. and react for 4 h, filter, wash with water, and dry to obtain polyethyleneimine-modified molecular sieve.

[0026] (3) Add water, ethanol, 20 g of polyethyleneimine modified molecular sieve, 3.8 g of manganese chloride, and 0.15 g of molybdenum trichloride into a reaction vessel, stir at 30° C. for 5 h, dry the solution to remove the solvent, place the product in a tubular furnace, heat it to 550° C. at a rate of 5° C. / min, keep it warm for 6 h, and cool it to obtain a manganese-based molecular sieve catalyst.

[0027] (4) Add 70 g of manganese-based molecular sieve catalyst and 30 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0028] Example 2

[0029] (1) Add 140 mL of water and 5 g of poloxamer template agent to a reaction container, stir to dissolve, then add 32 mL of concentrated hydrochloric acid, heat to 45° C., add 10 g of ethyl orthosilicate, stir for 60 min, then add 0.8 g of γ-glycidyloxypropyltrimethoxysilane, and then transfer the solution to a hydrothermal reactor, react at 110° C. for 18 h, filter, wash with ethanol to remove the template agent, and dry to obtain an epoxy SBA-15 molecular sieve.

[0030] (2) Add 300 mL of water and 15 g of epoxy SBA-15 molecular sieve into a reaction container, disperse by ultrasonication, then add 3 g of polyethyleneimine, heat to 50° C. and react for 8 h, filter, wash with water, and dry to obtain polyethyleneimine-modified molecular sieve.

[0031] (3) Add water, ethanol, 20 g of polyethyleneimine modified molecular sieve, 5 g of manganese nitrate, and 0.2 g of molybdenum acetylacetonate into a reaction vessel, stir at 20° C. for 6 h, dry the solution to remove the solvent, place the product in a tubular furnace, heat it up to 450° C. at a rate of 10° C. / min, keep it warm for 6 h, and cool it to obtain a manganese-based molecular sieve catalyst.

[0032] (4) Add 74 g of manganese-based molecular sieve catalyst and 26 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0033] Example 3

[0034] (1) Add 150 mL of water and 5.6 g of poloxamer template agent to a reaction container, stir to dissolve, then add 35 mL of concentrated hydrochloric acid, heat to 40° C., add 10 g of ethyl orthosilicate, stir for 30 min, then add 1.2 g of γ-glycidyloxypropyltrimethoxysilane, and then transfer the solution to a hydrothermal reactor, react at 100° C. for 24 h, filter, wash with ethanol to remove the template agent, and dry to obtain an epoxy SBA-15 molecular sieve.

[0035] (2) Add 400 mL of water and 15 g of epoxy SBA-15 molecular sieve into a reaction container, disperse by ultrasound, then add 7.5 g of polyethyleneimine, heat to 60° C. and react for 3 h, filter, wash with water, and dry to obtain polyethyleneimine-modified molecular sieve.

[0036] (3) Add water, ethanol, 20 g of polyethyleneimine modified molecular sieve, 1 g of manganese acetylacetonate, and 0.06 g of molybdenum trichloride into a reaction vessel, stir at 20° C. for 3 h, dry the solution to remove the solvent, place the product in a tubular furnace, heat it to 600° C. at a rate of 10° C. / min, keep it warm for 4 h, and cool it to obtain a manganese-based molecular sieve catalyst.

[0037] (4) Add 78 g of manganese-based molecular sieve catalyst and 22 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0038] Example 4

[0039] (1) Add 150 mL of water and 6 g of poloxamer template agent to a reaction container, stir to dissolve, then add 35 mL of concentrated hydrochloric acid, heat to 40° C., add 10 g of ethyl orthosilicate, stir for 30 min, then add 0.6 g of γ-glycidyloxypropyltrimethoxysilane, and then transfer the solution to a hydrothermal reactor, react at 100° C. for 24 h, filter, wash with ethanol to remove the template agent, and dry to obtain an epoxy SBA-15 molecular sieve.

[0040] (2) Add 400 mL of water and 15 g of epoxy SBA-15 molecular sieve into a reaction container, disperse by ultrasonication, then add 4.2 g of polyethyleneimine, heat to 60° C. and react for 5 h, filter, wash with water, and dry to obtain polyethyleneimine-modified molecular sieve.

[0041] (3) Add water, ethanol, 20 g of polyethyleneimine modified molecular sieve, 2.3 g of manganese sulfate, and 0.1 g of molybdenum trichloride to a reaction container, stir at 40° C. for 3 h, dry the solution to remove the solvent, place the product in a tubular furnace, heat it to 450° C. at a rate of 5° C. / min, keep it warm for 5 h, and cool it to obtain a manganese-based molecular sieve catalyst.

[0042] (4) Add 82 g of manganese-based molecular sieve catalyst and 18 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that a manganese-based molecular sieve catalyst is used as a polymer denitrification agent, and no melamine-urea-formaldehyde resin is added.

[0045] Comparative Example 2

[0046] The difference between this comparative example and Example 1 is that molybdenum trichloride is not added when preparing the manganese-based molecular sieve catalyst.

[0047] (1) Add water, ethanol, 20 g of polyethyleneimine modified molecular sieve, and 3.8 g of manganese chloride into a reaction vessel, stir at 30° C. for 5 h, dry the solution to remove the solvent, place the product in a tubular furnace, heat it up to 550° C. at a heating rate of 5° C. / min, keep it warm for 6 h, and cool it to obtain a manganese-based molecular sieve catalyst.

[0048] (2) Add 70 g of manganese-based molecular sieve catalyst and 30 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0049] Comparative Example 3

[0050] The difference between this comparative example and Example 1 is that polyethyleneimine is not added.

[0051] (1) Add water, ethanol, 20 g of epoxy SBA-15 molecular sieve, 3.8 g of manganese chloride, and 0.15 g of molybdenum trichloride to a reaction container, and stir at 30° C. for 5 h. Dry the solution to remove the solvent, and place the product in a tubular furnace at a heating rate of 5° C. / min to 550° C., keep the temperature for 6 h, and cool to obtain a manganese-based molecular sieve catalyst.

[0052] (2) Add 70 g of manganese-based molecular sieve catalyst and 30 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0053] Comparative Example 4

[0054] The difference between this comparative example and Example 1 is that when preparing the SBA-15 molecular sieve, γ-glycidyloxypropyltrimethoxysilane is not added.

[0055] (1) Add 150 mL of water and 5.2 g of poloxamer template agent to a reaction container, stir to dissolve, add 32 mL of concentrated hydrochloric acid, heat to 40° C., add 10 g of ethyl orthosilicate, stir for 30 min, transfer the solution to a hydrothermal reactor, react at 110° C. for 18 h, filter, wash with ethanol to remove the template agent, and dry to obtain SBA-15 molecular sieve.

[0056] (2) Add 400 mL of water and 15 g of SBA-15 molecular sieve into a reaction container, disperse by ultrasound, then add 5.8 g of polyethyleneimine, heat to 80° C. and react for 4 h, filter, wash with water, and dry to obtain a modified molecular sieve.

[0057] (3) Add water, ethanol, 20 g of modified molecular sieve, 3.8 g of manganese chloride, and 0.15 g of molybdenum trichloride to a reaction container, stir at 30° C. for 5 h, dry the solution to remove the solvent, place the product in a tubular furnace, heat it to 550° C. at a heating rate of 5° C. / min, keep it warm for 6 h, and cool it to obtain a manganese-based molecular sieve catalyst.

[0058] (4) Add 70 g of manganese-based molecular sieve catalyst and 30 g of melamine-urea-formaldehyde resin into a mixer, mix and discharge the materials to obtain a granular polymer denitrification agent.

[0059] The denitrification performance of the denitrifier was tested in a fixed bed reactor. The filling amount of the denitrifier was 3 mL and the reaction space velocity was 25000 h -1 , the test temperature is 900-1100℃, the concentration of NO in the flue gas is 1000ppm (C0), the concentration of O2 is 8%, and N2 is used as the balance gas. The concentration of NO in the flue gas at the outlet of the fixed bed reactor after the reaction reaches a stable state is tested using a flue gas analyzer (C1). The NO conversion rate R is calculated. R=(C0-C1) / C0×100%. The results are shown in Table 1.

[0060] Table 1 NO conversion test

[0061]

[0062]

[0063] In Examples 1-4, γ-glycidyloxypropyltrimethoxysilane was added during the preparation of the molecular sieve to obtain an SBA-15 molecular sieve containing an epoxy group, and then the epoxy group reacted with part of the amino group of polyethyleneimine to obtain a polyethyleneimine grafted modified molecular sieve. The polyethyleneimine molecular chains introduced on the surface served as adsorption sites to carry out complex adsorption on manganese and molybdenum ions, and manganese and molybdenum were uniformly adsorbed on the surface of the SBA-15 molecular sieve. After high-temperature calcination, the manganese and molybdenum catalytic active centers were uniformly distributed on the surface of the molecular sieve catalyst, thereby exposing more manganese and molybdenum denitrification catalytic centers. After compounding with melamine-urea-formaldehyde resin, the obtained granular polymer denitrification agent exhibited higher catalytic NO conversion rate and denitrification performance.

[0064] In Comparative Example 1, no melamine-urea-formaldehyde resin was added, and a manganese-based molecular sieve catalyst was used as a polymer denitrification agent. The NO conversion rate was low and the denitrification performance was poor.

[0065] In Comparative Example 2, molybdenum trichloride was not added, and the obtained manganese-based molecular sieve catalyst did not contain manganese-molybdenum denitration catalytic centers, had low catalytic performance, low NO conversion rate, and poor denitration performance.

[0066] The epoxy SBA-15 molecular sieve of Comparative Example 3 is not grafted with polyethyleneimine, and the manganese and molybdenum ions are not uniformly adsorbed on the surface of the SBA-15 molecular sieve, resulting in poor dispersion of the generated manganese and molybdenum denitrification catalytic centers in the molecular sieve, fewer denitrification catalytic centers, lower NO conversion rate, and poor denitrification performance.

[0067] In Comparative Example 4, when preparing SBA-15 molecular sieve, γ-glycidyloxypropyltrimethoxysilane was not added, and the obtained molecular sieve did not contain epoxy groups, and could not react with polyethyleneimine subsequently. Polyethyleneimine was not grafted to the surface of the molecular sieve, and it was difficult to uniformly adsorb manganese and molybdenum ions on the surface of the SBA-15 molecular sieve, resulting in poor dispersion of the generated manganese and molybdenum denitrification catalytic centers in the molecular sieve, fewer denitrification catalytic centers, lower NO conversion rate, and poor denitrification performance.

[0068] The above describes some embodiments of the present invention, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A granular polymer denitrification agent, characterized in that: The granular polymer denitrification agent comprises 18-30 parts by weight of melamine-urea-formaldehyde resin and 70-82 parts by weight of manganese-based molecular sieve catalyst; The preparation method of the manganese-based molecular sieve catalyst comprises: Step (1), adding water and epoxy SBA-15 molecular sieve into a reaction container, dispersing by ultrasonication, then adding polyethyleneimine, filtering after the reaction, washing, and drying to obtain polyethyleneimine modified molecular sieve; Step (2), adding water, ethanol and polyethyleneimine modified molecular sieve, manganese source and molybdenum source in a mass ratio of 100:(5-25):(0.3-1) into a reaction container, drying the solution to remove the solvent after stirring, placing the product in a tubular furnace, heating to a calcination temperature, heat preservation treatment, and cooling to obtain a manganese-based molecular sieve catalyst.

2. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (1), the mass ratio of epoxy SBA-15 molecular sieve to polyethyleneimine is 100:(20-50).

3. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (1), the reaction temperature is 50-80°C and the reaction time is 3-8h.

4. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (2), the manganese source is at least one of manganese nitrate, manganese sulfate, manganese chloride and manganese acetylacetonate.

5. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (2), the molybdenum source includes at least one of molybdenum trichloride and molybdenum acetylacetonate.

6. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (2), the stirring temperature is 20-40° C. and the stirring time is 3-6 hours.

7. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (2), the heating rate is 5-10°C / min, the calcination temperature is 450-600°C, and the insulation time is 4-6h.

8. The granular polymer denitrification agent according to claim 1, characterized in that: In the step (2), the preparation method of the epoxy SBA-15 molecular sieve comprises: adding water and a poloxamer template agent into a reaction container, stirring and dissolving, adding concentrated hydrochloric acid, heating to 40-45° C., adding tetraethyl orthosilicate, stirring for 30-60 min, then adding γ-glycidyloxypropyltrimethoxysilane, and then transferring the solution to a hydrothermal reactor, reacting at 100-110° C. for 18-24 h, filtering, washing with ethanol to remove the template agent, and drying to obtain the epoxy SBA-15 molecular sieve.

9. The granular polymer denitrification agent according to claim 8, characterized in that: The mass ratio of the poloxamer template agent, tetraethyl orthosilicate and gamma-glycidyloxypropyltrimethoxysilane is (50-60):100:(6-12).

10. A method for preparing a granular polymer denitrification agent according to any one of claims 1 to 9, characterized in that: The preparation method comprises: adding a manganese-based molecular sieve catalyst and a melamine-urea-formaldehyde resin into a mixer, mixing and discharging the materials to obtain a granular polymer denitrifying agent.

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