Temperature-resistant high molecular denitration agent and preparation method thereof

Abstract

The application relates to the technical field of denitration agents, and discloses a temperature-resistant high-molecular denitration agent and a preparation method thereof. The high-molecular denitration agent comprises 60-75 parts by weight of a MOFs-based bimetallic oxide catalyst, 25-40 parts by weight of melamine-urea-formaldehyde resin, 1.5-3 parts by weight of sodium hydroxide and 0.6-1.2 parts by weight of calcium carbonate. A solvent thermal reaction is carried out on a 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid, a manganese source and a cobalt source to obtain a bimetallic MOFs, and then high-temperature calcination is carried out to obtain a novel MOFs-based bimetallic oxide catalyst. The MOFs-based bimetallic oxide catalyst is compounded with the melamine-urea-formaldehyde resin as a main agent, sodium hydroxide and calcium carbonate to obtain a denitration catalyst. The NO conversion rate of the denitration catalyst reaches 88.9-96.5%, and the denitration catalyst exhibits good denitration performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of denitration agents, in particular to a temperature-resistant high-molecular denitration agent and a preparation method thereof. BACKGROUND

[0002] In the process of coal-fired boiler operation, waste incineration, etc., a large amount of nitric oxide, nitrogen dioxide, sulfur dioxide and other gases will be produced. These gases can cause air pollution problems such as acid rain and photochemical smog, which have a great impact on the environment and human health and safety. The current denitration process mainly includes high-molecular non-catalytic reduction method, selective catalytic reduction method, selective non-catalytic reduction method, etc.

[0003] The high-molecular non-catalytic reduction method decomposes at high temperature to generate active groups such as carbon-nitrogen and carbon-oxygen, which react with nitric oxide in flue gas to generate non-polluting substances such as nitrogen and water, thereby achieving efficient denitration. The patent for invention with publication number CN115970487A discloses a high-molecular resin denitration agent and a preparation method thereof. Urea, melamine and formaldehyde are polymerized into amine-based high-molecular resin, and then an alkali metal promoter is added to obtain a high-molecular resin denitration agent which has strong heat resistance and can well improve the denitration performance. The combination of the high-molecular resin denitration agent and the inorganic metal catalyst can further improve the denitration performance. SUMMARY

[0004] The technical problem solved by the present application is to provide a temperature-resistant high-molecular denitration agent with high denitration rate.

[0005] The technical solution provided by the present application is: a temperature-resistant high-molecular denitration agent, which comprises 60-75 parts by weight of MOFs-based bimetallic oxide catalyst, 25-40 parts by weight of melamine-urea-formaldehyde resin, 1.5-3 parts by weight of sodium hydroxide and 0.6-1.2 parts by weight of calcium carbonate.

[0006] The preparation method of the MOFs-based bimetallic oxide catalyst comprises:

[0007] (1) N,N-dimethylformamide, water, ethanol, manganese source, cobalt source and 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid are added to a flask, and after stirring, the solution is poured into a hydrothermal reaction kettle, centrifuged after reaction, washed with water and ethanol in sequence, and dried to obtain a bimetallic MOFs.

[0008] (2) The bimetallic MOFs are placed in a tube furnace, heated to a calcination temperature, subjected to heat preservation treatment, and cooled to obtain a MOFs-based bimetallic oxide catalyst.

[0009] Preferably, in (1), the volume ratio of N,N-dimethylformamide, water and ethanol is 100:(12-20):(5-15).

[0010] Preferably, in (1), the molar ratio of the manganese source, the cobalt source and 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid is (88-95):(5-12):50.

[0011] Preferably, in (1), the manganese source is manganese nitrate or manganese sulfate.

[0012] Preferably, in (1), the cobalt source is cobalt nitrate or cobalt sulfate.

[0013] Preferably, in (1), the reaction temperature is 100-130℃, and the reaction time is 12-18h.

[0014] Preferably, in (2), the heating rate is 1-2℃ / min, the calcination temperature is 500-600℃, and the holding time is 2-3h.

[0015] Preferably, the preparation method of the melamine-urea-formaldehyde resin comprises: adding formaldehyde aqueous solution into a flask equipped with a condenser, adding sodium hydroxide to adjust the pH to 8-8.5, then adding urea, heating to 90-95℃, reacting for 40-60min, adding formic acid to adjust the pH to 4.5-5, adding urea again, reacting for 30-40min, adding sodium hydroxide to adjust the pH to 9-9.5, adding melamine, reacting for 60-90min, cooling and discharging, and drying to remove water, to obtain the melamine-urea-formaldehyde resin.

[0016] Preferably, the molar ratio of formaldehyde, urea and melamine is (4.2-4.8):(0.3-0.4):1.

[0017] Preferably, the preparation method of the temperature-resistant high molecular denitration agent comprises: adding the MOFs-based bimetallic oxide catalyst, the melamine-urea-formaldehyde resin, calcium carbonate and sodium hydroxide into a mixer, and mixing and discharging to obtain the temperature-resistant high molecular denitration agent.

[0018] The technical effect of the present application is that the present application carries out solvothermal reaction on 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid, a manganese source and a cobalt source, to obtain a bimetallic MOFs, and then carries out high-temperature calcination to obtain a novel MOFs-based bimetallic oxide catalyst.

[0019] The present application uses the MOFs-based bimetallic oxide catalyst and the melamine-urea-formaldehyde resin as the main agent of the denitration catalyst, and is compounded with sodium hydroxide and calcium carbonate, so that the NO conversion rate of the obtained denitration catalyst reaches 88.9-96.5%, and the denitration performance is good. DETAILED DESCRIPTION

[0020] In order to make the purposes, technical solutions and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be described clearly and completely below in combination with the embodiments of the present disclosure. Obviously, the described embodiments are only some of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work are within the protection scope of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other in any manner without conflict.

[0021] Embodiment 1

[0022] (1) 200 mL of N,N-dimethylformamide, 24 mL of water, 10 mL of ethanol, 9.5 mmol of manganese nitrate, 0.5 mmol of cobalt nitrate, 5 mmol of 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid were added into a flask, the solution was poured into a hydrothermal reaction kettle after stirring, and reacted at 130℃ for 12 h, cooled, centrifuged, washed with water, ethanol in turn, and dried to obtain a bimetallic MOF.

[0023] (2) The bimetallic MOF was placed in a tube furnace, the heating rate was 1℃ / min, the temperature was raised to 500℃, and the temperature was kept for 2 h, and then cooled to obtain a MOF-based bimetallic oxide catalyst.

[0024] (3) 800 mL of an aqueous solution containing 4.5 moles of formaldehyde was added into a flask equipped with a condenser, sodium hydroxide was added to adjust the pH to 8, then 0.12 moles of urea was added, heated to 95℃, reacted for 40 min, formic acid was added to adjust the pH to 4.5, and then 0.28 moles of urea was added, reacted for 40 min, sodium hydroxide was added to adjust the pH to 9.5, 0.1 moles of melamine was added, reacted for 60 min, and then the material was discharged after cooling, and dried to remove water to obtain a melamine-urea-formaldehyde resin.

[0025] (4) 60 g of the MOF-based bimetallic oxide catalyst, 40 g of the melamine-urea-formaldehyde resin, 0.8 g of calcium carbonate, and 2.2 g of sodium hydroxide were added into a mixer, mixed, and discharged to obtain a temperature-resistant polymer denitration agent.

[0026] Embodiment 2

[0027] (1) Add 200 mL N,N-dimethylformamide, 40 mL water, 30 mL ethanol, 9.2 mmol manganese nitrate, 0.8 mmol cobalt nitrate, and 5 mmol 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid to a flask, stir, and then pour the solution into a hydrothermal reactor. React at 120 °C for 12 h, cool, centrifuge, wash with water and ethanol in sequence, and dry to obtain bimetallic MOFs.

[0028] (2) Place the bimetallic MOFs in a tube furnace, heat at a rate of 1℃ / min, heat to 600℃, hold for 3h, and cool to obtain MOFs-based bimetallic oxide catalyst.

[0029] (3) Add 600 mL of an aqueous solution containing 4.8 mol of formaldehyde to a flask equipped with a condenser, add sodium hydroxide to adjust the pH to 8.5, then add 0.1 mol of urea, heat to 90°C, react for 60 min, add formic acid to adjust the pH to 5, add 0.25 mol of urea, react for 40 min, add sodium hydroxide to adjust the pH to 9.5, add 0.1 mol of melamine, react for 60 min, cool and discharge, dry to remove water, and obtain melamine-urea-formaldehyde resin.

[0030] (4) Add 75g of MOFs-based bimetallic oxide catalyst, 25g of melamine-urea-formaldehyde resin, 0.6g of calcium carbonate, and 3g of sodium hydroxide to the mixer, mix and discharge to obtain a heat-resistant polymer denitrification agent.

[0031] Example 3

[0032] (1) Add 200 mL N,N-dimethylformamide, 24 mL water, 10 mL ethanol, 8.8 mmol manganese sulfate, 1.2 mmol cobalt sulfate, and 5 mmol 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid to a flask. After stirring, pour the solution into a hydrothermal reactor and react at 100 °C for 18 h. After cooling, centrifuge and separate the contents. Wash with water and ethanol in sequence, and dry to obtain bimetallic MOFs.

[0033] (2) Place the bimetallic MOFs in a tube furnace, heat at a rate of 2℃ / min, heat to 600℃, hold for 2h, and cool to obtain MOFs-based bimetallic oxide catalyst.

[0034] (3) Add 600 mL of an aqueous solution containing 4.2 mol of formaldehyde to a flask equipped with a condenser, add sodium hydroxide to adjust the pH to 8, then add 0.1 mol of urea, heat to 90°C, react for 40 min, add formic acid to adjust the pH to 5, add another 0.2 mol of urea, react for 30 min, add sodium hydroxide to adjust the pH to 9, add 0.1 mol of melamine, react for 90 min, cool and discharge, dry to remove water, and obtain melamine-urea-formaldehyde resin.

[0035] (4) Add 67g of MOFs-based bimetallic oxide catalyst, 33g of melamine-urea-formaldehyde resin, 1.2g of calcium carbonate, and 1.5g of sodium hydroxide to the mixer, mix and discharge to obtain a heat-resistant polymer denitrification agent.

[0036] Comparative Example 1

[0037] The difference between this comparative example and Example 1 is that no MOF-based bimetallic oxide catalyst was added.

[0038] (1) Add 40g of melamine-urea-formaldehyde resin, 0.8g of calcium carbonate, and 2.2g of sodium hydroxide to the mixer, mix and discharge to obtain a heat-resistant polymer denitrification agent.

[0039] Comparative Example 2

[0040] The difference between this comparative example and Example 1 is that melamine-urea-formaldehyde resin is not added.

[0041] (1) Add 60g of MOFs-based bimetallic oxide catalyst, 0.8g of calcium carbonate, and 2.2g of sodium hydroxide to a mixer, mix and discharge to obtain a denitrification agent.

[0042] Comparative Example 3

[0043] The difference between this comparative example and Example 1 is that 4,4'-biphenyldicarboxylic acid was used instead of 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid when preparing bimetallic MOFs.

[0044] (1) Add 200 mL of N,N-dimethylformamide, 24 mL of water, 10 mL of ethanol, 9.5 mmol of manganese nitrate, 0.5 mmol of cobalt nitrate, and 5 mmol of 4,4'-biphenyldicarboxylic acid to a flask. After stirring, pour the solution into a hydrothermal reactor and react at 130 °C for 12 h. After cooling, centrifuge and separate the solutions. Wash with water and ethanol in sequence, and dry to obtain bimetallic MOFs.

[0045] (2) Place the bimetallic MOFs in a tube furnace, heat at a rate of 1℃ / min, heat to 500℃, hold for 2h, and cool to obtain MOFs-based bimetallic oxide catalyst.

[0046] (3) Add 60g of MOFs-based bimetallic oxide catalyst, 40g of melamine-urea-formaldehyde resin, 0.8g of calcium carbonate, and 2.2g of sodium hydroxide to the mixer, mix and discharge to obtain a heat-resistant polymer denitrification agent.

[0047] Comparative Example 4

[0048] The difference between this comparative example and Example 1 is that cobalt nitrate was not added when preparing bimetallic MOFs.

[0049] (1) Add 200 mL N,N-dimethylformamide, 24 mL water, 10 mL ethanol, 10 mmol manganese nitrate, cobalt nitrate, and 5 mmol 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid to a flask, stir, pour the solution into a hydrothermal reactor, react at 130 °C for 12 h, cool, centrifuge, wash with water and ethanol in sequence, and dry to obtain manganese-based MOFs.

[0050] (2) Place manganese-based MOFs in a tube furnace, heat at a rate of 1℃ / min, heat to 500℃, hold for 2h, and cool to obtain MOFs-based metal oxide catalyst.

[0051] (3) Add 60g of MOFs-based metal oxide catalyst, 40g of melamine-urea-formaldehyde resin, 0.8g of calcium carbonate, and 2.2g of sodium hydroxide to the mixer, mix and discharge to obtain a heat-resistant polymer denitrification agent.

[0052] The denitrification performance of the denitrification agent was tested in a fixed-bed reactor. The loading amount of the denitrification agent was 3 mL, and the reaction space velocity was 25000 h⁻¹. -1 The test temperature was 900-1100℃, the NO concentration in the introduced flue gas was 1000ppm (C0), the O2 concentration was 8%, and N2 was used as the balance gas. The NO concentration (C1) in the flue gas at the outlet of the fixed-bed reactor was measured using a flue gas analyzer after the reaction reached a steady state.

[0053] Calculate the NO conversion rate R. R = (C0 - C1) / C0 × 100%, and the results are shown in Table 1.

[0054] Table 1 NO Conversion Rate Test

[0055]

[0056]

[0057] After testing, the MOF-based manganese-cobalt bimetallic oxide catalysts obtained in Examples 1-3, using 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid as a ligand and melamine-urea-formaldehyde resin as the main denitrification agent, achieved a NO conversion rate of 88.9-96.5% at 950℃, demonstrating excellent denitrification performance.

[0058] Comparative Example 1 did not include a MOF-based bimetallic oxide catalyst. Comparative Example 2 did not include a melamine-urea-formaldehyde resin. Both showed poor NO conversion rates and poor denitrification performance.

[0059] Comparative Example 3, using 4,4'-biphenyldicarboxylic acid as a ligand, yielded a MOFs-based manganese cobalt bimetallic oxide catalyst with poor catalytic performance, a lower NO conversion rate than in Example 1, and poor denitrification performance.

[0060] In Comparative Example 4, no cobalt nitrate was added during the preparation of bimetallic MOFs. The resulting MOF-based manganese-based metal oxide catalyst exhibited poor catalytic performance, with a lower NO conversion rate than in Example 1 and poor denitrification performance.

[0061] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A temperature-resistant polymeric denitrification agent, characterized in that, The heat-resistant polymeric denitrification agent is composed of the following raw materials: 60g MOFs-based bimetallic oxide catalyst, 40g melamine-urea-formaldehyde resin, 0.8g calcium carbonate, and 2.2g sodium hydroxide; the preparation method of the polymeric denitrification agent includes: adding MOFs-based bimetallic oxide catalyst, melamine-urea-formaldehyde resin, calcium carbonate, and sodium hydroxide to a mixer, mixing and discharging to obtain the heat-resistant polymeric denitrification agent; The preparation method of the MOFs-based bimetallic oxide catalyst includes: (1) Add 200 mL N,N-dimethylformamide, 24 mL water, 10 mL ethanol, 9.5 mmol manganese nitrate, 0.5 mmol cobalt nitrate, and 5 mmol 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxylic acid to a flask, stir, and then pour the solution into a hydrothermal reactor. React at 130 °C for 12 h, cool, centrifuge, wash with water and ethanol in sequence, and dry to obtain bimetallic MOFs; (2) Place the bimetallic MOFs in a tube furnace, heat at a rate of 1℃ / min, heat to 500℃, hold for 2h, and cool to obtain MOFs-based bimetallic oxide catalyst. The preparation method of the melamine-urea-formaldehyde resin includes: adding 800 mL of an aqueous solution containing 4.5 mol of formaldehyde to a flask equipped with a condenser, adding sodium hydroxide to adjust the pH to 8, then adding 0.12 mol of urea, heating to 95°C, reacting for 40 min, adding formic acid to adjust the pH to 4.5, then adding 0.28 mol of urea, reacting for 40 min, adding sodium hydroxide to adjust the pH to 9.5, adding 0.1 mol of melamine, reacting for 60 min, cooling and discharging, drying and removing water to obtain melamine-urea-formaldehyde resin; The NO conversion rate of the polymeric denitrification agent is 96.5% at 950℃.

2. A method for preparing the heat-resistant polymeric denitrification agent as described in claim 1, characterized in that, The preparation method includes: adding MOFs-based bimetallic oxide catalyst, melamine-urea-formaldehyde resin, calcium carbonate, and sodium hydroxide to a mixer, mixing and discharging to obtain a temperature-resistant polymeric denitrification agent.

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