Rare earth water-based environment-friendly urea crystal scavenger for vehicles and preparation method thereof

Abstract

The invention relates to the field of special medicament materials for environmental pollution treatment of atmospheric pollution materials, in particular to a rare-earth water-based environment-friendly urea crystal scavenger for vehicles and a preparation method thereof. The urea crystal scavenger for the rare earth water-based environment-friendly vehicle is prepared from the following raw materials in parts by mass: 0.005-0.2 part of a rare earth-based catalyst, 3-10 parts of a surfactant, 1-3 parts of a dispersing agent, 5-10 parts of a stabilizer and 80-100 parts of deionized water, wherein the rare earth-based catalyst at least comprises a cerium-based catalyst. The urea crystal cleaning agent provided by the invention has an excellent use effect, can effectively remove urea crystals, has a cerium emission concentration far lower than EURO 7 draft requirements (EURO 7 has no requirements for cerium), has significantly improved NOx conversion rate, is more suitable for automobiles using high-sulfur fuels, and has great benefits for mobile source atmospheric pollution control. The environment is safe and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the field of special agent materials for treating atmospheric pollution materials and environmental pollution, and in particular to a rare earth water-based environmentally friendly vehicle urea crystal remover and a preparation method thereof. Background Art

[0002] In the current booming automotive industry, diesel and gasoline vehicles bring convenience to people's travel and cargo transportation, but also cause serious environmental and health problems. During the operation of vehicles, nitrogen oxides (NO x ) and other harmful gases. These gases discharged into the atmosphere will seriously damage the atmospheric environment and pose a great threat to human health. They can easily induce respiratory diseases and endanger people's lives and health.

[0003] As global environmental awareness continues to increase, environmental regulations are becoming increasingly stringent, and diesel vehicles must meet more stringent emission standards. In order to meet these standards, according to regulations, diesel engine vehicles must add urea, such as urea aqueous solution AUS32. In this exhaust gas treatment process, selective catalytic reduction (SCR) technology plays a key role. In the SCR catalytic system, urea aqueous solution AUS32 is precisely injected into the exhaust gas after-treatment device and rapidly decomposed into ammonia under high temperature conditions. Subsequently, under the catalytic action of the metal-based catalyst, ammonia undergoes an oxidation-reduction reaction with nitrogen oxides in the exhaust gas, and is eventually converted into harmless nitrogen and water for discharge, thereby significantly reducing NO in the exhaust gas. x The content makes vehicle emissions more environmentally friendly and in line with regulatory standards.

[0004] However, in practical applications, the addition of aqueous urea solution AUS32 also brings a series of new technical problems. The composition of aqueous urea solution AUS32 by mass percentage includes 32.5% high-purity vehicle urea, 57.5% water, and 10% antifreeze. In the high-temperature environment of 140 - 220 °C in the exhaust pipe, the water in the aqueous urea solution will evaporate rapidly, and at the same time, urea crystals (composition: urea, biuret, triuret, etc.) are extremely likely to form after the condensation reaction of the aqueous urea solution. These crystals often appear in key parts such as the end of the urea injection unit, flange, and the front end of the SCR catalytic system in the exhaust pipe, thus blocking the SCR carrier and even the exhaust system, seriously affecting the engine performance, increasing fuel consumption, decreasing power, and sharply increasing carbon emissions. In a cold environment, the solute in the aqueous urea solution will crystallize out due to low temperature, and urea crystals (composition: urea) will also be produced. In addition, in the low-temperature environment in winter, more than 50% of the National V and National VI vehicles have experienced urea crystallization. Factors such as using inferior diesel, unreasonable exhaust pipe design layout, and poor maintenance of the SCR catalytic system will also promote the generation of urea crystals. The existence of urea crystals not only interferes with the normal operation of the engine but also significantly reduces the utilization rate of urea, increases fuel consumption, and it is very difficult for the exhaust gas to meet the standards.

[0005] Currently, to avoid the many problems brought by urea crystallization, the industry has taken a variety of countermeasures. For example, go to a professional repair station for ultrasonic cleaning or high-temperature ablation of the exhaust system, regularly check and maintain the SCR catalytic system to ensure the normal operation of the urea pump and filter; vehicle owners can also improve their driving habits, avoid directly turning off the main power supply after the vehicle stops, and ensure that the urea pump is emptied thoroughly; at the same time, choose high-quality aqueous urea solution and avoid using products containing impurities such as high aldehydes and phosphates. However, considering cost factors comprehensively, using a urea crystal remover is undoubtedly the most economical, practical, and fast method. However, the existing urea crystal removers still have problems such as unsatisfactory effects and poor stability in actual use, unable to effectively meet the market demand, and far behind the world's advanced level.

[0006] Therefore, developing an efficient, environmentally friendly, stable, and economical urea crystal remover has become a key issue that the industry urgently needs to address. To address this, the applicant previously applied for an invention patent, CN119608240A, which discloses a urea crystal remover. The raw materials for its preparation, calculated by weight, include: 0.2 parts of copper acetate, 4 parts of AEO-10, 2 parts of MOA3-PK (fatty alcohol polyoxyethylene ether potassium phosphate), 4 parts of PEG-400, 0.5 parts of isopropyl alcohol, 0.5 parts of CAB-35, 0.1 parts of methylene blue, and 88.7 parts of deionized water. The product can effectively remove urea crystals after use. However, the applicant further discovered that excessive use of MOA3-PK or use of inferior urea AUS32 solution may produce new fatty alcohol polyoxyethylene ether phosphate salt impurities and cause urea crystals precipitated at the bottom of the vehicle-mounted urea tank to be easily adsorbed by the urea pump onto the urea filter, causing malfunctions.

[0007] At present, there is an urgent need for a new type of automotive urea crystal remover that can effectively remove urea crystals while maintaining high stability and not easily generating new precipitation. This is the key research direction of current technological improvements. Summary of the Invention

[0008] As an implementable case, the first aspect of the present application provides a rare earth water-based environmentally friendly automotive urea crystal scavenger, the raw materials for its preparation, calculated by mass, include: 0.005-0.2 parts of rare earth-based catalyst, 3-10 parts of surfactant, 1-3 parts of dispersant, 5-10 parts of stabilizer, and 80-100 parts of deionized water; the rare earth-based catalyst includes at least a cerium-based catalyst.

[0009] As an implementable example, the cerium-based catalyst includes: one or more of cerium sulfate, cerium nitrate, cerium acetate or cerium citrate.

[0010] Furthermore, the cerium-based catalyst is cerium citrate.

[0011] In the present invention, cerium citrate (Ce(C6H5O7)) is selected as a cerium-based catalyst, which can achieve efficient removal of urea crystals through a multi-dimensional synergistic mechanism. 3+ / Ce 4+ The redox reaction catalyzes the hydrolysis of urea to generate NH3 and CO2, reducing the local concentration and inhibiting crystallization. At low temperatures (120℃~220℃), it still accelerates the generation of hydroxyl radicals through valence changes to enhance activity. At the same time, citrate acts as a multidentate ligand to selectively complex Ca 2+ Mg 2+It can remove impurity ions such as cerium and prevent double salt crystallization, and stabilize the dispersion state of cerium ions by electrostatic repulsion to avoid low-temperature precipitation; in addition, its weak alkalinity can maintain the urea hydrolysis environment, avoiding the poisoning of the vanadium-tungsten catalyst in the SCR carrier by acidic conditions, and synergistically reduce the surface tension of the solution with components such as AEO-10 and PEG-400, inhibiting crystal aggregation. By precisely controlling the cerium content, the negative impact on the original SCR catalyst is avoided, the service life of the SCR system is significantly extended, and NO X With a conversion rate exceeding 10%, harmful vehicle exhaust emissions are significantly reduced, meeting future Euro VII emission standards. Furthermore, the extremely low concentration significantly reduces operating costs. Compared to a comparable European product (Würth Group's Wirkstoff MF987 SCR system, a 1:400 concentration), this technology is 25% lower, achieving the highest level of technology globally and significantly reducing the risk of atmospheric pollution from mobile air pollution sources.

[0012] As an implementable case, the rare earth-based catalyst also includes a lanthanum-based catalyst.

[0013] Furthermore, the lanthanum-based catalyst includes one or more of lanthanum sulfate, lanthanum nitrate, lanthanum acetate or lanthanum citrate.

[0014] Furthermore, when the catalyst includes a cerium-based catalyst and a lanthanum-based catalyst, the mass ratio of the cerium-based catalyst to the lanthanum-based catalyst is 1:(0.05-0.1).

[0015] Furthermore, when the catalyst includes a cerium-based catalyst and a lanthanum-based catalyst, the mass ratio of the cerium-based catalyst to the lanthanum-based catalyst is 1:0.1.

[0016] Furthermore, the lanthanum-based catalyst is lanthanum acetate.

[0017] The single-component cerium citrate can effectively ablate urea crystals. However, in actual R & D, the applicant found that excessive use of cerium citrate may cause cerium ions to occupy the original SCR vanadium-titanium-tungsten catalyst or the electronic active sites of the catalyst molecular sieve, resulting in emissions not meeting the national VI motor vehicle exhaust emission standards, and also leading to a relatively long effective mileage. Therefore, lanthanum acetate and cerium citrate are selected for compound use at a mass ratio of [1:(0.05 - 0.1)]. The introduction of lanthanum acetate forms a bimetallic catalytic system, which optimizes the reaction kinetics by adjusting the local electron cloud density, significantly improving the generation efficiency of hydroxyl radicals at low temperatures and increasing the urea decomposition rate by 10% - 20%. The compound use of the two also has a certain synergistic effect. Cerium citrate preferentially adsorbs sulfides in the exhaust gas, reducing its poisoning of the vanadium-tungsten catalyst in the SCR system, while lanthanum acetate further reduces the sulfur deposition rate through strong sulfur affinity, extending the life of the SCR carrier and sensor by more than 4000 hours, and the cerium content is controlled at ≤0.01%, which is lower than 0.3 times the safety threshold of the vanadium catalyst, avoiding interference with the original SCR catalytic function, solving the low-temperature precipitation problem of the traditional solvent isopropanol, meeting the national VI / Euro VI emission standards, and even meeting the future Euro VII (draft) standards. Finally, the cerium emission is <0.1 mg / km, which is especially effective for vehicles using high-sulfur fuels.

[0018] As an implementable case, the surfactant includes fatty alcohol polyoxyethylene ether.

[0019] Further, the HLB (hydrophilic-lipophilic balance) value of the fatty alcohol polyoxyethylene ether is 12 - 14.

[0020] Furthermore, the fatty alcohol polyoxyethylene ether is AEO-10, and its hydrophilic-lipophilic value is 12 - 14.

[0021] In the prior application CN119608240A, the applicant selected the compounding of AEO-10 and MOA-3PK (potassium alcohol polyoxyethylene ether phosphate), and selected isopropanol as the solvent, which can improve the long-term stability of the urea crystallization scavenger. However, when selecting the compounding of AEO-10 and MOA-3PK and encountering poor-quality urea AUS32 solution, new impurities of alcohol polyoxyethylene ether phosphate salt may precipitate and cause the urea crystals to precipitate at the bottom of the vehicle-mounted urea tank, which is instead easily adsorbed by the urea pump onto the urea filter, resulting in failures. Therefore, in the present invention, single-component AEO-10 is used as the surfactant. AEO-10 can significantly reduce the surface tension of the urea solution, promote the uniform spreading of the solution on the surface of the SCR catalytic converter, and at the same time inhibit the aggregation of crystal particles through electrostatic repulsion. In addition, the cloud point of AEO-10 reaches 6o-70°C, and it still maintains liquid fluidity at a low temperature of -10°C, avoiding the low-temperature precipitation problem of traditional solvents. It synergistically enhances the solution permeability with the cerium-based catalyst, improves the urea hydrolysis efficiency by reducing the solution viscosity, and stabilizes the dispersion state of cerium citrate. At the same time, its weak alkalinity inhibits the poisoning of the vanadium-tungsten catalyst by acidic substances, extending the service life of the SCR carrier to more than 24,000 hours, and at the same time, it is not easy to generate new impurity precipitates that affect the normal operation of the SCR system.

[0022] As an implementable case, the stabilizer includes ethylene glycol tert-butyl ether.

[0023] The moderate polarity and non-polar groups of ethylene glycol tert-butyl ether can not only dissolve the cerium citrate catalyst to form a uniform solution, but also cooperate with AEO-10 to reduce the surface tension of urea, enhance the wettability of the surface of the SCR catalytic converter in the exhaust pipe, and stabilize the dispersion state of cerium ions through the hydrogen bond network of ether oxygen atoms, avoiding the low-temperature precipitation problem of traditional solvents such as isopropanol used in the prior application CN119608240A; the weak polar microenvironment regulation of ethylene glycol tert-butyl ether accelerates the urea hydrolysis kinetics, increasing the NH3 generation rate by 10%-20%, while inhibiting the excessive occupation of catalytic active sites by water molecules, and its biodegradability meets ISO22241-1 and the national VI / Euro VI emission standards.

[0024] As an implementable case, the dispersant includes one or more of polyethylene glycol, isopropanol, butanol, ethanol, propylene glycol, and butylene glycol.

[0025] Furthermore, the dispersant is polyethylene glycol (PEG).

[0026] Furthermore, the polyethylene glycol is PEG-400.

[0027] The second aspect of the present invention provides a preparation method of a rare earth water-based environmentally friendly vehicle urea crystal remover, which includes: mixing a rare earth-based catalyst, a surfactant, a dispersant, a stabilizer and deionized water to obtain the rare earth water-based environmentally friendly vehicle urea crystal remover.

[0028] Further, the preparation method of the rare earth water-based environmentally friendly vehicle urea crystal remover includes:

[0029] S1. Mix the dispersant and deionized water, and stir at 20 - 30 °C for 5 - 10 min;

[0030] S2. Then add the surfactant and stir at 20 - 30 °C for 30 - 40 min;

[0031] S3. Then add the stabilizer and stir at 20 - 30 °C for 5 - 10 min;

[0032] S4. Then add the rare earth-based catalyst and stir at 20 - 30 °C for 5 - 10 min to obtain the rare earth water-based environmentally friendly vehicle urea crystal remover.

[0033] The rare earth water-based environmentally friendly vehicle urea crystal remover prepared by the present invention can be used by mixing the product and the vehicle urea solution AUS32 in a mass ratio of 1:(500 - 600) evenly. It is fast and convenient to use, and has excellent urea crystal ablation effect, which can effectively extend the working operation time of the SCR system. At the same time, the extremely low concentration ratio greatly reduces the use cost. The ratio concentration is 25% lower than that of similar European products (1:400), and it is at the highest global technical level.

[0034] Beneficial effects

[0035] (1) In the present invention, cerium citrate, a rare earth-based catalyst, is selected as one of the raw material components. It catalyzes the AUS32 urea aqueous solution prior to the SCR carrier catalyst at low temperature, significantly improving the utilization rate of urea. And the cerium-based catalyst is relatively safe, environmentally friendly and has strong stability. The measured urea consumption is reduced by up to 24% compared with the urea without using the rare earth catalyst.

[0036] (2) In order to further reduce the effective mileage, citric acid and lanthanum acetate are selected as the rare earth-based catalyst in this application. At the same time, their synergistic effect further improves the removal effect of urea crystals.

[0037] (3) The present invention selects a single fatty alcohol polyoxyethylene ether AEO-10 as the surfactant, which can improve the long-term stability of the urea crystal remover; and since there is no MOA-3PK, the possibility of generating new impurity precipitation is reduced.

[0038] (4) The present invention selects PEG-400 as the dispersant and ethylene glycol tert-butyl ether as the stabilizer, which can further improve the ablation property of the product for urea crystallization.

[0039] (5) The urea crystallization scavenger prepared by the present invention is convenient to use. The product and the urea solution can be mixed at a volume ratio of 1:(500 - 600). It will not cause pollution to the environment, has high safety, and the effective mileage of the urea crystallization scavenger is less than 2500 km, with fast effectiveness and high long-term stability. All links from production to use are more environmentally friendly, can better protect the SCR carrier, and extend the service life of the SCR carrier.

[0040] (6) All the formula components in the present invention are listed in the ISO 22241-1 permission list, meet the Chinese GB 29518-2013 certification, the product is applicable to the sensitive catalytic system of the SCR system of national VI / Euro VI diesel vehicles, and still maintains the fluidity of the solution at -30°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the working principle of the urea crystallization scavenger in Example 1 of the present invention.

[0042] Figure 2 It is a schematic diagram of urea crystallization without using the rare earth water-based environmentally friendly vehicle urea crystallization scavenger in Example 1.

[0043] Figure 3 It is a schematic diagram of urea crystallization after using the rare earth water-based environmentally friendly vehicle urea crystallization scavenger in Example 1.

[0044] Figure 4 It is the odometer of the urea just using the rare earth water-based environmentally friendly vehicle urea crystallization scavenger prepared in Example 1.

[0045] Figure 5 It is the odometer of the urea after using up a barrel of the rare earth water-based environmentally friendly vehicle urea crystallization scavenger prepared in Example 1 (reset to zero when full 10000 km). DETAILED DESCRIPTION OF THE INVENTION

[0046] In the following implementation cases:

[0047] PEG-400 is purchased from Jinan Anqi Chemical Co., Ltd.

[0048] AEO-10 is purchased from Shanghai Huijun Chemical Co., Ltd.

[0049] Example 1

[0050] The first aspect of this example provides a rare earth water-based environmentally friendly vehicle urea crystal remover. The preparation raw materials, by mass fraction, include: 0.01 part of rare earth-based catalyst, 4 parts of surfactant, 3 parts of dispersant, 6 parts of stabilizer, and 86.99 parts of deionized water.

[0051] The rare earth-based catalyst is cerium citrate (CAS No.: 512-24-3).

[0052] The surfactant is AEO-10.

[0053] The dispersant is PEG-400.

[0054] The stabilizer is ethylene glycol tert-butyl ether (CAS No.: 7580-85-0).

[0055] The second aspect of this example provides a preparation method of a rare earth water-based environmentally friendly vehicle urea crystal remover, including:

[0056] S1. Mix the dispersant and deionized water, and stir at 25°C for 5 min;

[0057] S2. Then add the surfactant and stir at 25°C for 35 min;

[0058] S3. Then add the stabilizer and stir at 25°C for 5 min;

[0059] S4. Then add the rare earth-based catalyst and stir at 25°C for 10 min to obtain the rare earth water-based environmentally friendly vehicle urea crystal remover.

[0060] Example 2

[0061] The first aspect of this example provides a rare earth water-based environmentally friendly vehicle urea crystal remover. The preparation raw materials, by mass fraction, include: 0.011 part of rare earth-based catalyst, 4 parts of surfactant, 3 parts of dispersant, 6 parts of stabilizer, and 86.989 parts of deionized water.

[0062] The rare earth-based catalyst is cerium citrate (CAS No.: 512-24-3) and lanthanum acetate (CAS No.: 100587-90-4); the mass ratio of cerium citrate to lanthanum acetate is 10:1.

[0063] The surfactant is AEO-10.

[0064] The dispersant is PEG-400.

[0065] The stabilizer is ethylene glycol tert-butyl ether (CAS No.: 7580-85-0).

[0066] The second aspect of this example provides a method for preparing a rare earth water-based environmentally friendly automotive urea crystal scavenger, comprising:

[0067] S1. Mix the dispersant and deionized water and stir at 25°C for 5 minutes;

[0068] S2, add surfactant and stir at 25℃ for 35min;

[0069] S3, add stabilizer and stir at 25℃ for 5min;

[0070] S4. Add a rare earth-based catalyst and stir at 25° C. for 10 minutes to obtain a rare earth water-based environmentally friendly automotive urea crystal scavenger.

[0071] Comparative Example 1

[0072] In a first aspect of this example, a vehicle urea crystal scavenger is provided, wherein the raw materials for its preparation include, by weight, 4 parts of a surfactant, 3 parts of a dispersant, 6 parts of a stabilizer, and 87 parts of deionized water.

[0073] The surfactant is AEO-10.

[0074] The dispersant is PEG-400.

[0075] The stabilizer is ethylene glycol tert-butyl ether (CAS No.: 7580-85-0).

[0076] The second aspect of this example provides a method for preparing a vehicle urea crystal scavenger, comprising:

[0077] S1. Mix the dispersant and deionized water and stir at 25°C for 5 minutes;

[0078] S2, add surfactant and stir at 25℃ for 35min;

[0079] S3. Add stabilizer and stir at 25°C for 5 minutes to obtain automotive urea crystal scavenger.

[0080] Comparative Example 2

[0081] In a first aspect of this example, a vehicle urea crystal scavenger is provided, wherein the raw materials for its preparation include, by weight, 4 parts of a surfactant and 96 parts of deionized water.

[0082] The surfactant is AEO-10.

[0083] The second aspect of this example provides a method for preparing a vehicle urea crystal scavenger, comprising: mixing a surfactant and deionized water, and stirring the mixture uniformly to obtain the vehicle urea crystal scavenger.

[0084] Comparative Example 3 (refer to Example 1 in Invention Patent CN119608240A)

[0085] In the first aspect of this example, a copper-based urea crystal remover for vehicles is provided. The preparation raw materials, by mass, include: 0.2 parts of copper acetate, 4 parts of AEO-10, 2 parts of MOA-3PK, 4 parts of PEG-400, 0.5 parts of isopropyl alcohol, 0.5 parts of CAB-35 (cocamidopropyl betaine), 0.1 part of methylene blue, and 88.7 parts of deionized water.

[0086] Among them, copper acetate is purchased from Xiamen Haibiao Technology Co., Ltd.

[0087] PEG-400 is purchased from Guangzhou Nanjia Chemical Co., Ltd.

[0088] AEO-10 is purchased from Shanghai Huijun Chemical Co., Ltd.

[0089] MOA-3PK is purchased from Shanghai Huijun Chemical Co., Ltd.

[0090] Isopropyl alcohol is purchased from Shanghai Kelong Chemical Co., Ltd.

[0091] CAB-35 is purchased from Shandong Yousuo Chemical Technology Co., Ltd.

[0092] Methylene blue (CAS: 7220-79-3) is purchased from Zhengzhou Honghai Dye Chemical Co., Ltd.

[0093] Deionized water is purchased from Shanghai Jingchun Water Treatment Technology Co., Ltd.

[0094] In the second aspect of this example, a preparation method of a copper-based urea crystal remover for vehicles is provided, including:

[0095] S1. Dilute PEG-400 with deionized water, and then stir at 30 °C for 5 min;

[0096] S2. Then add AEO-10 and stir at 25 °C for 5 min;

[0097] S3. Then add isopropyl alcohol and stir at 25 °C for 5 min;

[0098] S4. Then add MOA-3PK and stir at 25 °C for 5 min;

[0099] S5. Then add copper acetate and stir at 25 °C for 10 min;

[0100] S6. Then add CAB-35 and stir at 20 °C for 5 min;

[0101] S7. Then add methylene blue and stir at 25 °C for 10 min to obtain the copper-based urea crystal remover for vehicles.

[0102] Performance Test

[0103] I. Average Effective Mileage Test

[0104] After excluding mechanical and electronic faults of the vehicle with urea crystallization fault, the urea crystallization remover of Example 1 and Comparative Examples 1-2 was fully mixed with the vehicle urea solution AUS32 at a mass ratio of 1:600, added to the urea tank of the faulty vehicle, and tested for transportation. Specifically, as Figure 1 shown, until the fault light is eliminated, which is the effective mileage. Each group was tested 4 times, and the average value was taken as the average effective mileage. The test results are shown in Table 1 for details.

[0105] There are two test routes. One is the round-trip line from Guangzhou to Shanghai, that is, traveling between Guangzhou and Shanghai; the other is the round-trip line from Guangzhou to Chengdu, denoted as traveling between Guangzhou and Chengdu. The driving distances of the Guangzhou-Shanghai line have basically the same altitude, and the driving distance of the Guangzhou-Chengdu line is from a low altitude area to a high altitude area.

[0106] The test vehicle is Scania G420. The engines of all Scania G420 vehicles are exactly the same, which can avoid the influence of experimental errors caused by different engine manufacturers and models.

[0107] Table 1

[0108]

[0109] It can be seen from Table 1 that the average effective mileage of the urea crystallization remover prepared in Example 1 is the shortest, and it has excellent urea crystallization ablation effect. In addition, it can be seen from Table 1 that for the same group of experiments, the effective mileage of the Guangzhou-Shanghai line is shorter than that of the Guangzhou-Chengdu line. The main reason is that as the altitude gradually increases in the Guangzhou-Chengdu line, the oxygen content in the air gradually decreases, the combustion performance of the engine decreases to a certain extent, and more pollutants are generated. Therefore, the effective mileage of the Guangzhou-Chengdu line is longer than that of the Guangzhou-Shanghai line.

[0110] II. Schematic Diagram of Urea Crystallization Ablation

[0111] Before using the urea crystallization remover of Test Example 1, after adding it and working for 6 days, 8 hours per day. The cumulative working time is 48 hours, and then disassemble and observe the SCR catalytic converter of the exhaust pipe of the vehicle with urea crystallization fault. The test results are as Figures 2-3 shown.

[0112] From Figures 2-3 it can be seen that by using the urea crystallization remover of Example 1, the urea crystallization amount in the SCR catalytic converter of the exhaust pipe of the vehicle with urea crystallization fault can be effectively reduced, and it falls off naturally.

[0113] The odometer readings of the urea just starting to use, which contains the rare-earth water-based environmentally friendly vehicle urea crystal remover prepared in Example 1, are as follows Figure 4 shown; the odometer readings of the urea after using up a barrel of urea containing the rare-earth water-based environmentally friendly vehicle urea crystal remover prepared in Example 1 are as shown in Figure 5 (reset to zero when reaching 10,000 km). It can be seen that this product is usable, and the supported usage mileage of urea reaches 1,316 km, while the urea without generally adding urea crystal cleaning agent can only be used for 900 - 1,000 km.

[0114] III. Effective mileage experiment

[0115] Fully mix the urea crystal cleaning agent prepared in Example 1 and the vehicle urea solution AUS32, and test the effective mileage. The test method is the same as that of Test 1. The experimental results are shown in Table 2 in detail.

[0116] Table 2

[0117]

[0118] The experimental results in Table 2 show that the shortest effective mileage of the urea crystal cleaning agent prepared in the present invention can reach 2,091 km, and the ablation effect of the urea crystal of the product is excellent.

[0119] Fully mix the urea crystal cleaning agents prepared in Examples 1 - 2 and the vehicle urea solution AUS32, and test the effective mileage. The test method is the same as that of Test 1. The experimental results are shown in Table 3 in detail.

[0120] Table 3

[0121]

[0122] The experimental results in Table 3 show that using the compound cerium citrate and lanthanum acetate as catalysts, the vehicle urea crystal remover has a more excellent ablation effect on urea crystals, and thus a shorter effective mileage.

[0123] IV. Stability experiment

[0124] Test the stabilities of the vehicle urea crystal remover in Example 1 and the copper-based vehicle urea crystal remover in Comparative Example 3 at different temperatures. The experimental results are shown in Table 4 in detail.

[0125] Table 4

[0126]

[0127] As can be seen from the experimental results in Table 4, the urea crystallization cleaner provided by the present application has more excellent low-temperature stability. This is mainly because compared with isopropanol, the ability of isopropanol to restrict the solution colloid is lower than that of ethylene glycol tert-butyl ether. At the same time, when the urea crystallization remover provided by the present application is compounded with inferior urea, there will be no phenomenon of solid precipitation, and it has a certain ability to protect the SCR carrier catalyst. However, when the urea crystallization remover provided in Comparative Example 3 is compounded with inferior urea, there will be a phenomenon of solid precipitation. At the same time, ethylene glycol tert-butyl ether has lower toxicity than isopropanol and is more environmentally friendly in the production process.

Claims

1. A rare earth water-based environmental protection vehicle urea crystal remover, characterized in that, The raw materials for preparation include, by weight, 0.005-0.2 parts of rare earth-based catalyst, 3-10 parts of surfactant, 1-3 parts of dispersant, 5-10 parts of stabilizer, and 80-100 parts of deionized water; The rare earth-based catalyst at least includes a cerium-based catalyst.

2. The rare earth water-based environmentally friendly vehicle urea crystallization remover according to claim 1, wherein The cerium-based catalyst includes one or more of cerium sulfate, cerium nitrate, cerium acetate or cerium citrate.

3. The rare earth water-based environmentally friendly vehicle urea crystallization remover according to claim 2, characterized in that, The rare earth-based catalyst may also include a lanthanum-based catalyst.

4. The rare earth water-based environmentally friendly vehicle urea crystallization remover according to claim 3, characterized in that, The lanthanum-based catalyst includes one or more of lanthanum sulfate, lanthanum nitrate, lanthanum acetate or lanthanum citrate.

5. The rare earth water-based environment-friendly vehicle urea crystallization remover according to claim 4, characterized in that, When the catalyst comprises a cerium-based catalyst and a lanthanum-based catalyst, the mass ratio of the cerium-based catalyst to the lanthanum-based catalyst is 1:(0.05-0.1).

6. The rare earth water-based environment-friendly vehicle urea crystal remover according to claim 1, characterized in that, The surfactant includes fatty alcohol polyoxyethylene ether.

7. The rare earth water-based environment-friendly vehicle urea crystallization remover according to claim 6, characterized in that, The HLB value of the fatty alcohol polyoxyethylene ether is 12-14.

8. The rare earth water-based environmentally friendly vehicle urea crystallization remover according to any one of claims 1-7, characterized in that, The stabilizer includes ethylene glycol tert-butyl ether.

9. The rare earth water-based environment-friendly vehicle urea crystal remover according to claim 1, characterized in that, The dispersant includes one or more of polyethylene glycol, isopropyl alcohol, butanol, ethanol, propylene glycol or butanediol.

10. A preparation method of the rare earth water-based environment-friendly vehicle urea crystallization remover according to any one of claims 1-9, characterized in that, The following steps are involved: The rare earth-based catalyst, surfactant, dispersant, stabilizer and deionized water are mixed to obtain a rare earth water-based environmentally friendly automotive urea crystal remover.

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