Environmentally friendly low-temperature vehicle exhaust gas treatment liquid and preparation method thereof

Abstract

The present application relates to the field of motor vehicle exhaust purification, and specifically discloses an environmentally friendly low-temperature vehicle exhaust treatment liquid and a preparation method thereof. An environmentally friendly low-temperature vehicle exhaust treatment liquid comprises the following raw materials in weight percentage: 32.5% automotive-grade high-purity urea, 3-5% polyethylene glycol, 2-3.5% glycerol, 5-6.5% octadecyl alcohol polyoxyethylene ether, 6.5-10% bacterial cellulose aerogel nanopowder, and the balance is ultrapure water. The exhaust treatment liquid of the present application is safe to use and has a lower freezing point. It is suitable for use in winter in cold northern regions, and has a better treatment effect on exhaust gas.

Description

Technical Field

[0001] The present application relates to the field of motor vehicle exhaust purification, and more specifically, to an environmentally friendly low-temperature vehicle exhaust gas treatment liquid and a preparation method thereof. Background Art

[0002] With the increasing prominence of air pollution and the rapid increase in the number of cars, exhaust gas emitted by cars has become one of the main sources of urban atmospheric pollution. The harmful substances in automobile exhaust are mainly CO, NOx and HC, polycyclic aromatic hydrocarbons (PAH) and suspended solids (SPM). NOx and HC undergo a series of photochemical reactions in the atmosphere, easily generating a variety of highly oxidizing substances such as ozone, forming photochemical smog. Photochemical smog not only seriously endangers human health, but also causes serious damage to animals, plants and various materials. With the increasingly stringent environmental protection system, automotive exhaust treatment fluid has gradually become a rigid need for drivers of National VI diesel vehicles. Automotive exhaust treatment fluid is commonly known as: automotive urea, automotive urea, automotive environmental protection urea, automotive denitrification agent, and the most common one is automotive urea.

[0003] At present, automotive urea solution is generally composed of 32.5% high-purity urea and 67.5% ultra-pure water. Urea solution with this concentration has the lowest crystallization point and will crystallize at temperatures below -11°C. For this reason, antifreeze automotive urea solution has appeared on the market.

[0004] In the prior art, a Chinese invention patent application document with application number CN201710409586.0 discloses a urea solution for diesel vehicles with low-temperature performance, which is composed of component A, component B, component C and component D; component A is high-purity water, component B is urea, component C is ethanolamine and / or diethanolamine, and component D is a small molecule liquid alcohol substance; the weight proportions of each component are: 40 to 70 parts of component A, 20 to 35 parts of component B, 5 to 25 parts of component C and 5 to 40 parts of component D.

[0005] The above-mentioned automotive urea solution is added with small molecule liquid alcoholamine substances and small molecule liquid alcohol substances, which can obtain automotive urea products with a freezing point below -(18-35)°C, which are suitable for use in cold seasons in Northeast China. However, since the small molecule liquid alcohol substances used, such as ethanol, methanol, ethylene glycol, etc., have strong volatility and flammable and explosive properties, there are great safety hazards in the actual processing process. Summary of the invention

[0006] In order to increase the low-temperature performance of automotive urea solutions and improve their safety, the present application provides an environmentally friendly low-temperature automotive exhaust gas treatment solution and a preparation method thereof.

[0007] In the first aspect, the present application provides an environmentally friendly low-temperature vehicle exhaust treatment fluid, which adopts the following technical solution:

[0008] An environmentally friendly low-temperature vehicle exhaust treatment liquid comprises the following raw materials in percentage by weight: 32.5% of vehicle-grade high-purity urea, 3-5% of polyethylene glycol, 2-3.5% of glycerol, 5-6.5% of octadecyl alcohol polyoxyethylene ether, 6.5-10% of bacterial cellulose aerogel nano powder, and the balance is ultrapure water.

[0009] By adopting the above technical scheme, glycerol, polyethylene glycol, octadecyl alcohol polyoxyethylene ether and the like are used as effective ingredients for reducing the freezing point of the exhaust gas treatment liquid. Glycerol has good stability and safety, can effectively reduce the freezing point of the urea solution, and will not cause damage to the vehicle and the SCR system. It also has a certain lubricating effect, which helps to reduce the crystallization and blockage of the urea solution; octadecyl alcohol polyoxyethylene ether has high surface activity, which makes the exhaust gas treatment liquid atomization effect better, urea is easier to decompose, and the occurrence of crystallization of the exhaust gas treatment liquid is reduced; there are a large number of hydrogen bonds and van der Waals forces in the molecular structure of polyethylene glycol, which make the polyethylene glycol molecules form in water. It forms a stable inclusion structure, which hinders the movement of water molecules and thus lowers the freezing point of the solution. Bacterial cellulose is a natural nanomaterial with a structure composed of bD-glucose monomers connected by b-1,4 glycosidic bonds and has biodegradable properties. This ultrafine, ultrapure cellulose has an ultra-fine three-dimensional network structure, a large number of nanoscale pore size distributions, a large specific surface area and a large number of surface hydroxyl groups. After it is made into aerogel nanopowder, due to the size effect and surface effect of the nanoparticles, the surface energy is high, and the solution and water molecules communicate with each other, which can effectively prevent the formation of ice crystals, thereby affecting the freezing point of the urea solution.

[0010] Optionally, the bacterial cellulose aerogel nanopowder is prepared as follows:

[0011] Add melamine to the formaldehyde solution, heat it to 60-65℃, stir and dissolve, heat it to 95-100℃, add agarose, stir and dissolve, cool it to 55-60℃, add bacterial cellulose and gC 3 N 4 After stirring, a mixed gel was obtained, including bacterial cellulose, agarose and gC 3 N 4 The mass ratio is 12∶0.6-0.7∶0.3-0.5;

[0012] The mixed gel is allowed to stand for aging, the solvent is replaced by anhydrous ethanol, and the mixture is dried by supercritical carbon dioxide and crushed to obtain bacterial cellulose aerogel nanopowder.

[0013] By adopting the above technical scheme, bacterial cellulose is a natural polysaccharide polymer with a fibrous structure, which can form a highly entangled network with abundant pores. Agarose has the advantages of a large number of hydroxyl groups, a network entanglement structure, non-toxicity, and easy degradation. Therefore, bacterial cellulose can form a semi-interpenetrating network with agarose. At the same time, bacterial cellulose is rich in a large number of hydroxyl polar groups, which can form intermolecular hydrogen bonds with agarose molecules, and can also form intramolecular hydrogen bonds by itself. 3 N 4 (Graphene phase carbon nitride) is non-toxic and environmentally friendly, has the advantages of simple raw material preparation method and low cost, and has a narrower band gap than carbon dioxide, which enables it to absorb a wider spectrum range and higher photocatalytic efficiency. Under the action of various light radiation, gC 3 N 4 The surface of the material can undergo redox reactions, degrading harmful gases into harmless substances such as small molecular organic matter, water and carbon dioxide. It can absorb light energy and generate active oxygen free radicals to achieve the degradation and conversion of carbon monoxide, hydrocarbons and nitrogen oxides in exhaust gas. In addition, the interpenetrating network formed by bacterial cellulose and agarose can be coated on gC 3 N 4 The hybrid gel thus obtained has a porous structure. Supercritical drying provides the hybrid gel with an interconnected pore network, which is beneficial to the transport and adsorption of other molecules. The microporous structure enables the gas molecules to experience significant gas-solid interactions through van der Waals forces and electrostatic interactions, increasing the possibility of exhaust gas impacting the treatment liquid and being captured, which helps to improve the adsorption capacity of exhaust gas. In addition, the increased specific surface area and micropore volume may provide a larger contact area and increase the number of exposed adsorption sites. The mesopores / macropores can serve as gas diffusion channels, promote exhaust gas penetration and mass transfer, improve diffusion efficiency, and achieve the maximum purification effect through diffusion and adsorption processes.

[0014] Optionally, the gC 3 N 4 After the following modification pretreatment: silver nitrate was added to deionized water, stirred until completely dissolved, and gC 3 N 4 and γ-Al 2 O 3 After ultrasonic homogenization, drying, calcination at 500-550℃ for 1.5-2h, γ-Al 2 O 3 , silver nitrate and gC 3 N 4 The mass ratio is 10:0.3-0.5:0.1-0.3.

[0015] By adopting the above technical solution, in order to further improve gC 3 N4 Degradation of tail gas using silver nitrate and Y-Al 2 O 3 Pretreatment, silver nitrate is calcined at high temperature, decomposition produces silver, oxygen and nitrogen, the generation of gas can increase gC 3 N 4 The porosity of silver / γ-Al 2 O 3 The composite can use hydrocarbons in the exhaust gas as a reducing agent to purify nitrogen oxides through catalytic reduction reactions, and significantly promote the activation of hydrocarbons in the exhaust gas and improve the nitrogen oxide reduction effect. 2 O 3 The oxidation process under the action of the catalyst can be divided into a partial oxidation stage and a complete oxidation stage. In the partial oxidation stage, γ-Al 2 O 3 It mainly promotes the adsorption and activation of hydrocarbons into acetic acid species, which can quickly react with nitrogen oxide adsorption and activation species to generate N 2 and H 2 O; In the complete oxidation stage, hydrocarbons are mainly converted into carbonate species, which do not participate in the HC-SCR reaction. After loading Ag, due to the active species Ag + The partial oxidation of hydrocarbons is further promoted and more acetic acid species are formed, thereby significantly improving the performance of hydrocarbons in reducing nitrogen oxides.

[0016] Optionally, 5-8% of a low-temperature auxiliary agent is added to the tail gas treatment liquid, and the preparation method of the low-temperature auxiliary agent is as follows:

[0017] Dissolve chitosan in glacial acetic acid solution, add sodium hyaluronate, stir to obtain a transparent solution, centrifuge, discard the supernatant, and obtain a hydrogel, wherein the mass ratio of chitosan to sodium hyaluronate is 1:1;

[0018] The zeolite is added to deionized water, ultrasonically formed into a suspension, sodium chloride is added, vacuum is drawn and the pressure is maintained for 20-30 minutes, and vacuum drying is performed to obtain a modified zeolite, wherein the mass ratio of the zeolite to the sodium chloride is 1:0.1-0.2;

[0019] The phytic acid solution and the modified zeolite are added to the hydrogel, mixed evenly, freeze-dried, and crushed to obtain a low-temperature auxiliary agent.

[0020] By adopting the above technical scheme, chitosan is currently the only natural cationic polysaccharide in nature, contains free amino groups, and has excellent biodegradability. Sodium hyaluronate is a natural high molecular polymer with good wettability. Moreover, a large number of hydroxyl groups are exposed on one side of the sodium hyaluronate molecular chain, making it highly hydrophilic and can combine with the amino groups on the protonated chitosan chain to form a physically cross-linked hydrogel through electrostatic interaction. The hydrogel has a three-dimensional network structure and is relatively uniform. It forms a network structure in the exhaust gas treatment liquid to prevent the expansion of ice crystals. The molecular chain carries many hydrophilic groups, which can form hydrogen bonds with water molecules to form a stable network structure in the solution. This structure can effectively prevent the expansion of ice crystals, lower the freezing point, and improve antifreeze properties. Moreover, these polymers also have thickening, suspension and emulsification properties.

[0021] Zeolite powder is a kind of aluminosilicate mineral with a unique skeleton structure. It has a rich pore structure and can better load the effective ingredients. Therefore, its porous structure is used to load sodium chloride. Zeolite powder is a negative thermal expansion material. In a low temperature environment, the pores of zeolite powder become larger, which has a good promoting effect on the rapid release of sodium chloride. Sodium chloride is a chloride salt that can lower the freezing point of water. The addition of zeolite can effectively lower the freezing point and delay the freezing process. It has a positive effect on the antifreeze property of the exhaust gas treatment fluid in a low negative temperature environment. In addition, zeolite is embedded in the network to Improve the mechanical strength of hydrogel; phytic acid, as a biomass substance, has six phosphate groups and rich hydrogen bond donors and acceptors. It can combine with water molecules through hydrogen bond interactions and affect the crystallization of water in hydrogels, thereby effectively enhancing the frost resistance of hydrogels. Even at -30°C, it can still maintain good flexibility and can be twisted and stretched. Phytic acid can also cooperate with glycerol. The hydrogen bond interaction between them and the electrostatic interaction between phytic acid and chitosan can make the hydrogel have a microcrack repair effect, thereby improving the anti-low temperature effect.

[0022] Optionally, the mass ratio of the phytic acid solution, modified zeolite and chitosan is 3-3.2:0.3-0.5:1.

[0023] By adopting the above technical scheme, with the addition of phytic acid solution and modified zeolite, the antifreeze performance and recovery performance of the hydrogel are gradually enhanced, the effect of preventing low-temperature crystallization damage is stronger, and the low-temperature stability is better.

[0024] Optionally, the molecular weight of the chitosan is 100 kDa, and the molecular weight of sodium hyaluronate is 97 kDa.

[0025] By adopting the above technical solution, chitosan and sodium hyaluronate with the above molecular weight can form a hydrogel with a more uniform three-dimensional network structure, larger pores and thinner pore walls.

[0026] Optionally, the concentration of the phytic acid solution is 65-70wt%.

[0027] By adopting the above technical solution, phytic acid molecules will interact with water molecules to form a phytic acid aqueous solution. As the concentration of phytic acid increases, the number of solute molecules in the solution increases, and the destructive effect on the orderly arrangement of solvent molecules increases, thereby causing the freezing point of the solution to gradually decrease.

[0028] Optionally, the specific surface area of ​​the zeolite is 400-420m2 / g.

[0029] By adopting the above technical solution, the zeolite powder with a larger specific surface area has a stronger adsorption capacity, and has a stronger adsorption capacity for sodium chloride.

[0030] Optionally, the polyethylene glycol is polyethylene glycol 200.

[0031] By adopting the above technical solution, polyethylene glycol with a lower molecular weight can more easily form an inclusion structure in water, and thus may show a better effect in lowering the freezing point.

[0032] In a second aspect, the present application provides a method for preparing an environmentally friendly low-temperature vehicle exhaust treatment fluid, which adopts the following technical solution:

[0033] A method for preparing an environmentally friendly low-temperature vehicle exhaust treatment liquid comprises the following steps:

[0034] Heat ultrapure water to 30-35°C, add automotive-grade high-purity urea under continuous stirring, heat to 38-40°C, stir to dissolve, add polyethylene glycol and glycerol at 38-40°C, stir evenly, add octadecyl alcohol polyoxyethylene ether and bacterial cellulose aerogel nanopowder, stir evenly and filter to obtain the exhaust gas treatment liquid.

[0035] By adopting the above technical solution, ultrapure water is heated and then added with automotive-grade high-purity urea, which can facilitate its dissolution. The preparation method is simple, and it is easy to achieve mass production. In addition, the composition is simple and the ingredients are safer.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. Since the present application adopts bacterial cellulose aerogel nanopowder, polyethylene glycol, glycerol, octadecyl alcohol polyoxyethylene ether and other components to prepare the exhaust gas treatment liquid, the nanopowder has a large specific surface area and contains a large number of surface hydroxyl groups, and has a high surface energy, and can interact with water molecules to prevent the formation of ice crystals. Octadecyl alcohol polyoxyethylene ether increases the surface activity of the exhaust gas treatment liquid and improves the exhaust gas atomization effect, while polyethylene glycol and glycerol can further reduce the freezing point of the exhaust gas treatment liquid and enhance its low-temperature applicability.

[0038] 2. In this application, bacterial cellulose, agarose, gC 3 N 4 The raw materials are mixed and made into aerogel powder through supercritical drying, which improves the porosity of the aerogel powder, increases the adsorption capacity of exhaust gas, and increases the hydroxyl content, further enhancing the low temperature resistance.

[0039] 3. In the present application, it is preferred to add a low-temperature auxiliary agent made of chitosan, sodium hyaluronate, zeolite, sodium chloride and other ingredients to the exhaust gas treatment liquid to improve the hindering effect on ice crystals and increase the exhaust gas adsorption capacity. DETAILED DESCRIPTION

[0040] The following examples further illustrate the present application in detail.

[0041] Preparation Example 1-8 of Bacterial Cellulose Aerogel Nanopowder

[0042] Preparation Example 1: Add 2g of melamine to 50ml of 3wt% formaldehyde solution, heat to 65℃, stir to dissolve, heat to 100℃, add 0.6g of agarose, stir to dissolve, cool to 55℃, add 12g of bacterial cellulose and 0.5g of gC 3 N 4 After stirring, a mixed gel was obtained, including bacterial cellulose, agarose and gC 3 N 4 The mass ratio is 12∶0.6∶0.5;

[0043] The mixed gel was aged at room temperature for 24 hours, and the solvent was replaced with anhydrous ethanol every 24 hours to completely remove moisture. It was supercritically dried with carbon dioxide at a temperature of 60°C and a pressure of 8 MPa, and crushed to obtain bacterial cellulose aerogel nanopowder.

[0044] Preparation Example 2: Add 2g of melamine to 50ml of 3wt% formaldehyde solution, heat to 60℃, stir to dissolve, heat to 95℃, add 0.7g of agarose, stir to dissolve, cool to 60℃, add 12g of bacterial cellulose and 0.3g of cellulose. 3 N 4 After stirring, a mixed gel was obtained, including bacterial cellulose, agarose and gC 3 N 4 The mass ratio is 12 ： 0.7 ： 0.3;

[0045] The mixed gel was aged at room temperature for 24 hours, and the solvent was replaced with anhydrous ethanol every 24 hours to completely remove moisture. It was supercritically dried with carbon dioxide at a temperature of 60°C and a pressure of 8 MPa, and crushed to obtain bacterial cellulose aerogel nanopowder.

[0046] Preparation Example 3: The difference from Preparation Example 1 is that no gC is added 3 N 4 .

[0047] Preparation Example 4: The difference from Preparation Example 1 is that an equal amount of bacterial cellulose is used instead of agarose.

[0048] Preparation Example 5: The difference from Preparation Example 1 is that gC 3 N 4 After the following modification pretreatment: 0.5g silver nitrate was added to 100g deionized water, stirred until completely dissolved, and 0.3g gC 3 N 4 and 10gγ-Al 2 O 3 After ultrasonic treatment for 30 min, drying and calcination at 500 °C for 2 h, γ-Al 2 O 3 , silver nitrate and gC 3 N 4 The mass ratio is 10:0.5:0.3.

[0049] Preparation Example 6: The difference from Preparation Example 1 is that gC 3 N 4 After the following modification pretreatment: 0.3g silver nitrate was added to 100g deionized water, stirred until completely dissolved, and 0.1g gC 3 N 4 and 10gγ-Al 2 O 3 After ultrasonication for 30 min, drying and calcination at 550 °C for 1.5 h, γ-Al 2 O 3 , silver nitrate and gC 3 N 4 The mass ratio is 10:0.3:0.1.

[0050] Preparation Example 7: The difference from Preparation Example 5 is that no silver nitrate is added.

[0051] Preparation Example 8: The difference from Preparation Example 5 is that no γ-Al is added 2 O 3 .

[0052] Preparation Examples 9-14 of Low Temperature Auxiliary Agents

[0053] Preparation Example 9: 10 g of chitosan was dissolved in 250 ml of 0.75% by volume glacial acetic acid solution, sodium hyaluronate was added, and the mixture was stirred to obtain a transparent solution. The mixture was centrifuged at 2000 r / min for 15 min, and the supernatant was discarded to obtain a hydrogel. The mass ratio of chitosan to sodium hyaluronate was 1:1, the molecular weight of chitosan was 100 kDa, and the molecular weight of sodium hyaluronate was 97 kDa.

[0054] 10g of zeolite was added to 1000ml of deionized water, ultrasonicated to form a suspension, 2g of sodium chloride was added, vacuumed to -0.05MPa and maintained at a pressure of 30min, and vacuum dried to obtain a modified zeolite. The mass ratio of zeolite to sodium chloride was 1:0.2, and the specific surface area of ​​zeolite was 400m 2 / g;

[0055] 32 g of phytic acid solution with a concentration of 70 wt % and 5 g of modified zeolite were added to the hydrogel, mixed evenly, freeze-dried, and crushed to 120 meshes.

[0056] Preparation Example 10: 10 g of chitosan was dissolved in 250 ml of 0.75% by volume glacial acetic acid solution, sodium hyaluronate was added, and the mixture was stirred to obtain a transparent solution. The mixture was centrifuged at 2000 r / min for 15 min, and the supernatant was discarded to obtain a hydrogel. The mass ratio of chitosan to sodium hyaluronate was 1:1, the molecular weight of chitosan was 100 kDa, and the molecular weight of sodium hyaluronate was 97 kDa.

[0057] 10g of zeolite was added to 1000ml of deionized water, ultrasonicated to form a suspension, 2g of sodium chloride was added, vacuumed to -0.05MPa and maintained at a pressure of 30min, and vacuum dried to obtain a modified zeolite. The mass ratio of zeolite to sodium chloride was 1:0.2, and the specific surface area of ​​zeolite was 420m 2 / g;

[0058] 30 g of phytic acid solution with a concentration of 65 wt % and 3 g of modified zeolite were added to the hydrogel, mixed evenly, freeze-dried, and crushed to 120 meshes.

[0059] Preparation Example 11: The difference from Preparation Example 9 is that no phytic acid solution is added.

[0060] Preparation Example 12: The difference from Preparation Example 9 is that no sodium chloride is added.

[0061] Preparation Example 13: The difference from Preparation Example 9 is that 10 g of chitosan is dissolved in 250 ml of 0.75% by volume glacial acetic acid solution, sodium hyaluronate is added, and stirred to obtain a transparent solution. The solution is centrifuged at 2000 r / min for 15 min, and the supernatant is discarded to obtain a hydrogel. The solution is freeze-dried and crushed to 120 mesh. The mass ratio of chitosan to sodium hyaluronate is 1:1, the molecular weight of chitosan is 100 kDa, and the molecular weight of sodium hyaluronate is 97 kDa.

[0062] Preparation Example 14: 10 g of zeolite was added to 1000 ml of deionized water, ultrasonicated to form a suspension, 2 g of sodium chloride was added, vacuumed to -0.05 MPa and maintained at a pressure of 30 min, and vacuum dried to obtain a modified zeolite. The mass ratio of zeolite to sodium chloride was 1:0.2, and the specific surface area of ​​the zeolite was 400 m 2 / g, to obtain a low-temperature auxiliary agent.

[0063] Example

[0064] Example 1: An environmentally friendly low-temperature vehicle exhaust treatment liquid, the raw material dosage is shown in Table 1, wherein the polyethylene glycol is polyethylene glycol 200, the octadecyl alcohol polyoxyethylene ether is selected from Nantong Jienuo Chemical, model S-185, and the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 1.

[0065] The method for preparing the above-mentioned environmentally friendly low-temperature vehicle exhaust gas treatment liquid comprises the following steps:

[0066] Heat ultrapure water to 30°C, add automotive-grade high-purity urea under continuous stirring, heat to 38°C at a rate of 2°C / min, stir to dissolve, add polyethylene glycol and glycerol at 38°C, stir evenly, add octadecyl alcohol polyoxyethylene ether and bacterial cellulose aerogel nanopowder, stir evenly, and filter through a 0.6μm, 0.5MPa filter pressure to obtain an exhaust gas treatment liquid.

[0067] Table 1 Amount of raw materials used for tail gas treatment liquid in Examples 1-4 and 11-12

[0068]

[0069]

[0070] Example 2: An environmentally friendly low-temperature vehicle exhaust treatment liquid, the raw material dosage is as shown in Table 1, wherein the polyethylene glycol is polyethylene glycol 200, the octadecyl alcohol polyoxyethylene ether is selected from Nantong Jienuo Chemical, model S-185, and the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 2.

[0071] The method for preparing the above-mentioned environmentally friendly low-temperature vehicle exhaust gas treatment liquid comprises the following steps:

[0072] Heat ultrapure water to 35°C, add automotive-grade high-purity urea under continuous stirring, heat to 40°C at a rate of 2°C / min, stir to dissolve, add polyethylene glycol and glycerol at 40°C, stir evenly, add octadecyl alcohol polyoxyethylene ether and bacterial cellulose aerogel nanopowder, stir evenly, and filter through a 0.6μm, 0.5MPa filter pressure to obtain an exhaust gas treatment liquid.

[0073] Example 3-4: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 1 in that the amounts of raw materials used are as shown in Table 1.

[0074] Example 5: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 1 in that the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 3.

[0075] Example 6: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 1 in that the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 4.

[0076] Example 7: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 1 in that the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 5.

[0077] Example 8: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 1 in that the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 6.

[0078] Example 9: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 7 in that the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 7.

[0079] Example 10: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 7 in that the bacterial cellulose aerogel nanopowder is prepared by Preparation Example 8.

[0080] Example 11: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid. The difference from Example 7 is that 8% of a low-temperature treatment agent is also added to the exhaust gas treatment liquid, and the low-temperature treatment agent is prepared by Preparation Example 9.

[0081] Example 12: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid. The difference from Example 7 is that 5% of a low-temperature treatment agent is also added to the exhaust gas treatment liquid, and the low-temperature treatment agent is prepared by Preparation Example 10.

[0082] Example 13: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which is different from Example 11 in that the low-temperature treatment agent is prepared by Preparation Example 11.

[0083] Example 14: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which differs from Example 11 in that the low-temperature treatment agent is prepared by Preparation Example 12.

[0084] Example 15: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which differs from Example 11 in that the low-temperature treatment agent is prepared by Preparation Example 13.

[0085] Example 16: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which differs from Example 11 in that the low-temperature treatment agent is prepared by Preparation Example 14.

[0086] Comparative Example

[0087] Comparative Example 1: An environmentally friendly low-temperature vehicle exhaust gas treatment liquid, which differs from Example 1 in that an equal amount of purified water is used to replace octadecanol polyoxyethylene ether.

[0088] Comparative Example 2: An environmentally friendly low-temperature vehicle exhaust treatment liquid, which differs from Example 11 in that an equal amount of purified water is used to replace the bacterial cellulose aerogel nanopowder.

[0089] Comparative Example 3: An environmentally friendly, low-temperature automotive exhaust treatment liquid comprises 32.5% automotive high-purity urea, 8% bacterial cellulose aerogel nanopowder prepared in Preparation Example 1, and the remainder purified water. The preparation method is as follows: ultrapure water is heated to 30°C, and automotive-grade high-purity urea white powder is added under continuous stirring. The mixture is heated to 32°C at a heating rate of 2°C / min and maintained until the urea is completely dissolved and a clear solution is formed. After the emulsification tank is naturally cooled to room temperature, the mixed solution is filtered through a 0.6μm, 0.5MPa filter element pressure.

[0090] Comparative Example 4: An environmentally friendly, low-temperature automotive exhaust treatment fluid comprises 32.5% automotive high-purity urea, 8% methanol and the remainder purified water, and the preparation method is as follows: ultrapure water is heated to 32°C, and automotive-grade high-purity urea white powder is slowly added to an emulsification tank under continuous stirring, and the mixture is heated to 32°C at a heating rate of 2°C / min and maintained until the urea is completely dissolved to form a clear solution, and then colorless methanol liquid is added to the clear solution. After stirring and mixing, the mixed solution is filtered through a 0.6μm, 0.5MPa filter element pressure after the emulsification tank is naturally cooled to room temperature.

[0091] Performance testing

[0092] 1. Freezing point detection: Take 100 ml of the tail gas treatment liquid prepared in the embodiment and the comparative example, inject it into a cooling tube with a stirring device, insert a calibrated thermometer into an appropriate position in the test tube, insert the test tube containing the sample solution and the thermometer into the freezing point tester, and after starting, record the freezing point temperature when a large amount of crystals appear. Use a KD-F8076 SH / T0090 freezing point tester and record the test results in Table 2.

[0093] 2. Nitrogen oxide treatment efficiency test: The method for producing nitrogen oxide waste gas for the test is as follows: 5kg of carbon steel is added into an open plastic barrel containing 10kg of 50% nitric acid to produce brown-red smoke of nitrogen oxide. The gas flow rate of the fan is 10-20m3 / min, so that the concentration of nitrogen oxide is 5000mg / L. Due to the unstable smoke concentration, the maximum concentration time period is taken for the experiment. New Pan Asia raw materials are used each time to prevent adverse effects caused by nitric acid dilution. The initial reaction temperature of nitrogen oxide is room temperature, about 20-25℃, and the reaction is an exothermic process.

[0094] The nitrogen oxide waste gas first enters the reflux condenser to condense the nitric acid volatilized in the waste gas into liquid; then enters the gas-liquid separator to separate the liquefied nitric acid from the nitrogen oxide waste gas; the gas after gas-liquid separation enters the bubbling absorption reaction device, and the nitrogen oxide waste gas reacts with the tail gas treatment liquid prepared in the bubbling absorption reaction device. The temperature of the tail gas treatment liquid is 60°C and the waste gas flow rate is 15m 3 / min, and finally the remaining gas after being treated by the treatment liquid in the bubbling absorption reaction device enters the jet pump circulation reactor, and the tail gas treatment liquid in the reactor further reacts with the uneliminated nitrogen oxides. The temperature of the tail gas treatment liquid is 60°C and the flow rate of the exhaust gas is 15m 3 / min, and finally the nitrogen oxide concentration was detected and recorded online at the outlet, and the nitrogen oxide treatment efficiency was calculated: (5000-outlet nitrogen oxide concentration) / 5000×100%, and the detection results were recorded in Table 2.

[0095] Table 2 Performance test of tail gas treatment fluid

[0096]

[0097]

[0098] It can be seen from the data in Table 2 that the use of the bacterial cellulose aerogel nanopowder prepared in the present application to prepare the exhaust gas treatment liquid in Examples 1-4 can effectively reduce the freezing point of the exhaust gas treatment liquid and improve the exhaust gas treatment effect.

[0099] In Example 5, the bacterial cellulose aerogel powder prepared in Preparation Example 3 was not added with gC 3 N 4 As can be seen from the data in Table 2, the freezing point of the tail gas treatment liquid prepared in Example 5 does not change much, but its treatment effect on nitrogen oxides becomes worse.

[0100] Example 6 Compared with Example 1, the freezing point of the tail gas treatment liquid prepared by using the bacterial cellulose aerogel powder prepared in Preparation Example 4 is shown, while the purification efficiency of nitrogen oxides does not change much.

[0101] Compared with Example 1, Examples 7 and 8 use silver nitrate and γ-Al 2 O 3 For gC 3 N 4 After pretreatment, the data in Table 2 show that the tail gas treatment liquids prepared in Examples 7 and 8 have increased treatment efficiency for nitrogen oxides, and the freezing point does not change much.

[0102] Compared with Example 7, Examples 9 and 10 respectively use the bacterial cellulose aerogel nanopowders prepared in Preparation Examples 7 and 8, wherein no silver nitrate and γ-Al are added. 2 0 3 As can be seen from the data in Table 2, the purification rate of nitrogen oxides by the tail gas treatment liquids prepared in Examples 9 and 10 is slightly weakened.

[0103] Compared with Example 7, low-temperature auxiliary agents are further added in Examples 11 and 12. It can be seen from the data in Table 2 that the freezing point of the exhaust gas treatment liquid prepared in Examples 11 and 12 is further reduced, and the nitrogen oxide treatment rate is slightly increased.

[0104] Example 13 uses the low-temperature treatment agent prepared in Preparation Example 11. Compared with Example 11, no phytic acid solution is added. It can be seen that the freezing point of the nitrogen oxide treatment liquid increases and the low-temperature antifreeze property is weakened.

[0105] In Example 14, compared with Example 11, the low-temperature treatment agent prepared in Preparation Example 12 was used. It can be seen that the freezing point of the exhaust gas treatment liquid increased, and the nitrogen oxide treatment effect did not change much.

[0106] In Example 15, the low-temperature treatment agent prepared in Preparation Example 13 was used. Compared with Example 11, the freezing point increased and the nitrogen oxide treatment effect decreased.

[0107] In Example 16, the low-temperature treatment agent prepared in Preparation Example 14 was used. Compared with Example 11, the freezing point increased, but the nitrogen oxide treatment capacity did not change much.

[0108] In Comparative Example 1, purified water was used instead of octadecyl alcohol polyoxyethylene ether. As shown in Table 2, the freezing point of the tail gas treatment liquid increased and the antifreeze effect became worse.

[0109] In Comparative Example 2, purified water was used instead of bacterial cellulose aerogel nanopowder. It can be seen that compared with Example 1, the freezing point of the tail gas treatment liquid increased and the nitrogen oxide treatment effect was affected.

[0110] In Comparative Example 3, only bacterial cellulose aerogel nanopowder, urea and purified water were used to prepare the tail gas treatment liquid. As can be seen from the data in Table 2, the freezing point of the tail gas treatment liquid obtained in Comparative Example 2 dropped, and the tail gas treatment effect became worse.

[0111] In Comparative Example 4, methanol is used to improve the freezing point of the exhaust gas treatment liquid, but the freezing point is only -20, and the effect on exhaust gas treatment is not good.

[0112] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An environmentally friendly low-temperature vehicle exhaust treatment fluid, characterized in that: The raw materials include the following weight percentages: 32.5% of automotive grade high-purity urea, 3-5% of polyethylene glycol, 2-3.5% of glycerol, 5-6.5% of octadecyl alcohol polyoxyethylene ether, 6.5-10% of bacterial cellulose aerogel nano powder, and the balance is ultrapure water.

2. The environmentally friendly low-temperature vehicle exhaust treatment fluid according to claim 1, characterized in that: The preparation method of the bacterial cellulose aerogel nano powder is as follows: Add melamine to formaldehyde solution, heat it to 60-65°C, stir and dissolve it, heat it to 95-100°C, add agarose, stir and dissolve it, cool it to 55-60°C, add bacterial cellulose and g-C3N4, stir and obtain a mixed gel, the mass ratio of bacterial cellulose, agarose and g-C3N4 is 12:0.6-0.7:0.3-0.5; The mixed gel is allowed to stand for aging, the solvent is replaced by anhydrous ethanol, and the mixture is dried by supercritical carbon dioxide and crushed to obtain bacterial cellulose aerogel nanopowder.

3. The environmentally friendly low-temperature vehicle exhaust treatment fluid according to claim 2, characterized in that: The g-C3N4 is subjected to the following modification pretreatment: silver nitrate is added to deionized water, stirred until completely dissolved, g-C3N4 and γ-Al2O3 are added, ultrasonically homogenized, dried, and calcined at 500-550°C for 1.5-2h. The mass ratio of γ-Al2O3, silver nitrate and g-C3N4 is 10:0.3-0.5:0.1-0.

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4. The environmentally friendly low-temperature vehicle exhaust gas treatment fluid according to claim 1, characterized in that: The tail gas treatment liquid is further added with 5-8% of a low temperature auxiliary agent, and the preparation method of the low temperature auxiliary agent is as follows: Dissolve chitosan in glacial acetic acid solution, add sodium hyaluronate, stir to obtain a transparent solution, centrifuge, discard the supernatant, and obtain a hydrogel, wherein the mass ratio of chitosan to sodium hyaluronate is 1:1; The zeolite is added to deionized water, ultrasonically formed into a suspension, sodium chloride is added, vacuum is drawn and the pressure is maintained for 20-30 minutes, and vacuum drying is performed to obtain a modified zeolite, wherein the mass ratio of the zeolite to the sodium chloride is 1:0.1-0.2; The phytic acid solution and the modified zeolite are added to the hydrogel, mixed evenly, freeze-dried, and crushed to obtain a low-temperature auxiliary agent.

5. The environmentally friendly low-temperature vehicle exhaust gas treatment fluid according to claim 4, characterized in that: The mass ratio of the phytic acid solution, the modified zeolite and the chitosan is 3-3.2:0.3-0.5:

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6. The environmentally friendly low-temperature vehicle exhaust treatment fluid according to claim 4, characterized in that: The molecular weight of the chitosan is 100 kDa, and the molecular weight of sodium hyaluronate is 97 kDa.

7. The environmentally friendly low-temperature vehicle exhaust gas treatment fluid according to claim 4, characterized in that: The concentration of the phytic acid solution is 65-70 wt %.

8. The environmentally friendly low-temperature vehicle exhaust treatment fluid according to claim 4, characterized in that: The specific surface area of ​​the zeolite is 400-420m 2 / g.

9. The environmentally friendly low-temperature vehicle exhaust gas treatment fluid according to claim 1, characterized in that: The polyethylene glycol is polyethylene glycol 200.

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