CN107138044B - Diesel vehicle urea solution with low-temperature performance and preparation method thereof - Google Patents

Abstract

The invention provides a diesel vehicle urea solution with low temperature performance and a preparation method thereof, wherein the diesel vehicle urea solution with low temperature performance comprises the following components: component A, component B, component C and Component D; the component A is high-purity water, the component B is urea, the component C is a small-molecule liquid alcohol amine substance, and the component D is a small-molecule liquid alcohol substance; the parts by weight of each component are: 40-70 parts of component A, 20-35 parts of component B, 5-25 parts of component C and 5-40 parts of component D. The urea solution for diesel vehicles with low temperature performance according to the present invention has a freezing point lower than -18°C to -35°C and a surface tension lower than that of ordinary vehicle urea, and is suitable for use in all seasons in the north and south, especially in the cold season in the northeast.

Description

A kind of urea solution for diesel vehicle with low temperature performance and preparation method thereof

technical field

The invention belongs to the field of diesel engine exhaust gas treatment, in particular to a diesel vehicle urea solution with low temperature performance and a preparation method thereof.

Background technique

In recent years, every winter, smog occurs frequently in most of the central and eastern regions, and the number of smog days is generally more than 5 days, and the overall trend of smog days across the country is increasing. Especially in the past two years, the smog weather has lasted longer. For example, in 2015, the number of days that the air reached the standard in Beijing was only 186. In 2016, the number of days that the air reached the standard in Beijing in November was less than 50%. Smog is a general expression for the excessive content of hundreds of suspended particulate matter in the atmosphere, especially PM2.5 (particles with aerodynamic equivalent diameter less than or equal to 2.5 microns) is considered to be the "culprit" of haze weather. Studies have shown that vehicle exhaust emissions account for about 30% of the country's total PM2.5 pollutants, and it is one of the "culprits" that cause smog weather in my country. Among them, exhaust pollution from heavy-duty diesel vehicles is as high as more than two-thirds. Data show that the nitrogen oxides and PM pollutants emitted by diesel vehicles, which only account for 17% of my country's car ownership, account for more than 60% and 90% of the total vehicle emissions, respectively. In order to reduce the pollution caused by automobile exhaust to the atmospheric environment, my country has fully implemented the National IV emission standards.

On May 15, 2014, the State Council issued the "2014-2015 Action Plan for Energy Conservation, Emission Reduction and Low-Carbon Development", which pointed out that by the end of 2014, the country will supply China IV standard vehicle diesel. During the "November" period in 2014, many provinces, including Jiangsu, Fujian, Sichuan, etc., issued their own national four oil promotion policies. The Ministry of Industry and Information Technology announced that from January 1, 2015, diesel vehicles nationwide will enforce the National IV emission standards. With the promotion and implementation of the National IV emission standards for vehicle diesel, the development of the domestic vehicle urea market has ushered in a new opportunity. Although this market has just started in recent years, the domestic demand potential is huge, and the sales of urea for vehicles will grow rapidly.

The main pollutant emissions of diesel engines are NOx (nitrogen oxides) and PM (particulate particles). Due to the influence of national conditions, oil products and other factors, the SCR route is adopted to upgrade the country IV. During the combustion process of the engine adopting the SCR technology route, the diesel has been fully burned by technical means to achieve the goal of effectively controlling PM emissions, while NOx needs to be reduced to nitrogen (N ₂ ) and Water (H ₂ O), the reducing agent necessary for this process is the vehicle urea solution. After the exhaust gas comes out of the turbocharger, it enters the exhaust pipe. The urea metering injection device is installed on the exhaust pipe. When the temperature reaches 300℃～500℃, the urea solution is injected. Under the action of the catalyst, the urea (NH ₂ CONH ₂ ) Hydrolysis produces NH ₃ and CO ₂ , which _reacts with NOx to generate nitrogen and water for discharge, while absorbing harmful flue gas particles.

The purity and cleanliness of urea solution for vehicles are relatively high. Compared with industrial urea, the content of biuret, insoluble matter, iron, sulfide, chloride, etc. has strict requirements. Because the SCR catalyst carrier is easily poisoned by metal ions and loses its catalytic effect, the urea solution for vehicles must use first-class ultrapure water in the electronics industry. At present, the urea solution for vehicles generally consists of 32.5% high-purity urea and 67.5% ultrapure water. The urea solution with this concentration has the lowest crystallization point and will crystallize when it is lower than -11 °C. In actual use, it will completely freeze at -20 °C, which limits its use in cold winter weather such as the north, especially the northeast. Adding modifiers to reduce the freezing point of the urea solution for vehicles is the most convenient and low-cost method. However, due to the high requirements of SCR catalysts for the purity and cleanliness of urea solutions for vehicles, metal salts that can significantly reduce the freezing point of the aqueous solution cannot be used. The selection range of modifiers is very limited, inorganic salts can only choose ammonium substances, and most organic modifiers choose amine or amide substances.

The search found that there are many existing patents using urea as the ammonia source and adding modifiers to improve the freezing point, but most of them are ammonium substances, such as ammonium formate, ammonium carbonate, ammonium bicarbonate, etc. When the content is high, the CO ₂ The detection amount is easy to exceed the standard, and the stability is poor and easy to decompose. Triethanolamine is used in Chinese published patent 201410193227 "Automobile exhaust emission purification treatment liquid", but the composition of the treatment liquid is very complex, which greatly increases the cost and difficulty of the process. ) is also exceeded. The complex composition is likely to easily poison the sensitive catalyst and affect its reactivity.

Many patents such as Chinese patent CN201110134706.3 "A kind of low-temperature vehicle urea solution composition", CN201110134698.2 "A kind of ultra-low temperature vehicle urea solution composition", CN201510015958 "A kind of low freezing point nitrogen oxide reducing agent and its preparation method" " and CN 201510017530 "A kind of ultra-low freezing point nitrogen oxide reducing agent and its preparation method" both use small molecule liquid alcohols as composite additives, but the components are more complicated than this patent, which increases the difficulty of the process. In addition, all of them contain formamide, which is flammable. In the presence of a catalyst, heating to below 35 ° C can decompose highly toxic hydrogen cyanide, and can strongly corrode copper, brass, lead, and rubber, which is inconvenient. storage and transportation. CN201510015958 and CN 201510017530 also include sulfur-containing organic compound dimethyl sulfoxide, which may generate sulfur pollutants after high temperature decomposition. Because the composition of the modifier is simple and no restricted content is introduced in this formula, all quality indicators are qualified.

To sum up, the small-molecule liquid alcohol amine modifier used in the present invention does not involve the claims of the existing patent, and the formula is simple and the effect is remarkable.

SUMMARY OF THE INVENTION

In view of this, the present invention aims to propose a kind of urea solution for diesel vehicles with low temperature performance, to overcome the defects of the prior art, the liquid alcohol amine and the liquid alcohol modifier can be miscible with water, and can be mixed with the usual organic matter. It is soluble, simple in composition and preparation method, convenient in operation, does not introduce ingredients with limited content, and all quality indicators are qualified, and can be adapted to use in different regions, spring, summer, autumn, early winter and cold seasons.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

A urea solution for diesel vehicles with low temperature performance, comprising the following components: component A, component B, component C, and component D; the component A is high-purity water, the component B is urea, and the component B is urea. Component C is a small molecule liquid alcohol amine substance, and component D is a small molecule liquid alcohol substance.

Preferably, the parts by weight of each component are: 40-70 parts of component A, 20-35 parts of component B, 5-25 parts of component C and 5-40 parts of component D.

Preferably, the parts by weight of each component are: 45-65 parts of component A, 23-30 parts of component B, 8-22 parts of component C, and 9-35 parts of component D.

Preferably, the parts by weight of each component are: 50-60 parts of component A, 25-28 parts of component B, 13-20 parts of component C, and 15-28 parts of component D.

Preferably, the component C is ethanolamine and/or diethanolamine; the content of the component C is 20 parts.

Preferably, the component D is one or more of methanol, ethanol and ethylene glycol.

The high-purity water is industrial-grade high-purity water.

The urea needs to meet the technical requirements for AUS32 special urea in the GB29518-2013 "Diesel Engine Nitrogen Oxide Reductant Urea Aqueous Solution (AUS32)" standard.

The pure water needs to meet the technical requirements for pure water in the standard GB29518-2013 "Diesel Engine Nitrogen Oxide Reductant Urea Aqueous Solution (AUS32)"

The small-molecule liquid alcohol amine substances and the small-molecule liquid alcohol substances are all products of analytical purity or above.

Ethanolamine alias 2-hydroxyethylamine, molecular formula is HO(CH ₂ ) ₂ NH ₂ , colorless and transparent liquid, miscible with water, methanol, ethanol, acetone, etc., with good stability. Experiments show that after adding a certain amount of ethanolamine to ordinary vehicle urea, the freezing point of the solution is significantly reduced. In order to reduce the cost, the content of ethanolamine should not be too high, preferably 20%, and some low molecular weight liquid alcohols can be added at the same time. In addition, diethanolamine is also miscible with water, ethanol, etc., and it is conceivable to add one or more of them.

Small molecule liquid alcohols, such as methanol (-97°C, 0.792g/cm ³ ) and ethanol (-114°C, 0.798g/cm ³ ), can make the urea solution have a lower freezing point and lower density. Low freezing point and viscosity. However, due to their strong volatility and strong flammability of volatiles, they should not be added too much. After compounding with liquid alkanolamine, the volatility of methanol and ethanol is obviously weakened. Although ethylene glycol is often used in the preparation of automobile antifreeze, its density is slightly higher, which will increase the viscosity of the urea solution and reduce the fluidity, so it is not advisable to add too much. In consideration of cost, availability, safety and viscosity, methanol is preferred in the present invention, and various combinations of methanol, ethanol and ethylene glycol can be selected according to properties and effects.

When the urea solution for vehicle is sprayed into the exhaust pipe of the engine, the atomization effect is a very critical issue. _The atomization effect is good, and the injected urea has a small particle size, which can be rapidly hydrolyzed, pyrolyzed, entered into the catalyst carrier section, diffused to the catalyst surface, adsorbed, and reacted. The atomization effect is closely related to the surface tension of the reducing agent solution. At room temperature, the surface tension of water is 72mN/m. The traditional vehicle urea solution is prepared with high-purity urea and water. /m or less, ethylene glycol is 50 mN/m. It can be predicted that the surface tension of the traditional urea solution will definitely decrease after the above substances are added, and the smaller the reducing agent droplets are injected, thereby improving the atomization effect of the urea solution for vehicles.

The conductivity also has a certain influence on the use of the urea solution. The lower the conductivity, the slower the flow of the solution charge in the reaction system, which is easy to cause charge accumulation and form a flowing potential. Potentially dangerous. Since the organic alcohol amine is basically not ionized and the conductivity is very small, adding it into the urea solution will inevitably lead to a decrease in its conductivity. However, even when the addition amount is 20%, the conductivity of the urea solution is still greater than 300 μS/cm compared with the conductivity of the first-grade industrial electronic water less than 1 μS/cm, which has higher conductivity.

Another object of the present invention is to provide a method for preparing the above-mentioned urea solution for diesel vehicles with low temperature performance, so as to prepare the above-mentioned urea solution for diesel vehicles with low temperature performance.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

A method for preparing the above-mentioned urea solution for diesel vehicles with low temperature performance, comprising the following steps:

(1) Component B is added to Component A, and it is fully dissolved to obtain a transparent solution;

(2) Component C and Component D are sequentially added to the transparent solution described in step (1), fully stirred and mixed, and the obtained mixed solution obtains the urea solution for diesel vehicles with low temperature performance according to the present invention.

Preferably, in the step (2), the component C and the component D are sequentially added to the transparent solution described in the step (1), fully stirred and mixed, and the obtained mixed solution is filtered to obtain the Low temperature performance of urea solution for diesel vehicles.

Preferably, in the step (2), the obtained mixed solution is pressure filtered with a filter element of 0.5-0.8 μm and 0.6 Mpa to obtain the urea solution for diesel vehicles with low temperature performance according to the present invention.

Preferably, in the step (1), the component B is added to the component A, and it is fully dissolved at 35°C to 40°C to obtain a transparent solution; in the step (2), after the step (1) After the transparent solution in the solution is cooled to room temperature, component C is added, and after component C is completely dissolved, component D is added.

The preparation method of the present invention is applied to the small-scale preparation of laboratory products, and the preparation process comprises the following steps:

(1) Add high-purity urea into the round-bottomed flask to which high-purity water has been added, seal with a ground plug, heat to 35°C to 40°C, and stir until the urea is completely dissolved, and the solution is transparent;

(2) Cool the solution obtained in step (1) to room temperature, add a small molecule liquid alcohol amine substance, seal with a grinding plug, and stir until the solution is completely mixed evenly.

(3) adding small molecular liquid alcohols to the solution obtained in step (2), sealing with a grinding plug, and stirring until the solution is completely mixed evenly.

(4) Filtering the solution obtained in step (3) with filter element pressure with a filtration precision of 0.8 pm and 0.6 Mpa to obtain the urea solution for diesel vehicles with low temperature performance according to the present invention.

The preparation method of the present invention is applied to the preparation of pilot scale and commercial products, and the preparation method is as follows: all raw materials are proportionally enlarged, vigorously stirred until the urea is completely dissolved, and then solid amide substances and small molecular liquid alcohol are added in sequence After the solution is pressure filtered with a filter element of 0.5-0.8 μm and 0.6 Mpa, it is the urea solution for diesel vehicles with low temperature performance according to the present invention.

Compared with the prior art, the urea solution for diesel vehicles with low temperature performance of the present invention has the following advantages:

The urea solution for diesel vehicles with low temperature performance according to the present invention, the liquid alcohol amine and the liquid alcohol modifier are miscible with water, miscible with common organic matter, simple in composition and preparation method, convenient in operation, No ingredients with restricted content are introduced, all quality indicators are qualified, (meeting the requirements of ISO 22241-1:2006 international standard, DIN 70070:2005 German standard and DB11/552-2008 Beijing standard), the freezing point of the product is lower than -18 ℃ ～-35℃, the surface tension is lower than that of ordinary vehicle urea solution, the atomization effect is good, and it has high conductivity, which can improve the NOx reduction efficiency.

In the urea solution for diesel vehicles with low temperature performance according to the present invention, the detected amounts of carbonate and chloride both meet the requirements in the DB11/552-2008 Beijing standard (due to the ISO 22241-1:2006 international standard and The DIN 70070:2005 German standard does not require the detection amount of carbonate and chloride, so the DB11/552-2008 Beijing standard is referenced), and the detection amount of the two are: carbonate (calculated as CO _{2 )} . ) detection amount ≤ 0.2%, chloride detection amount ≤ 0.2%.

The method for preparing the above-mentioned urea solution for diesel vehicles with low temperature performance has the same advantages as the above-mentioned urea solution for diesel vehicles with low temperature performance relative to the prior art, and will not be repeated here.

Detailed ways

Unless otherwise defined, technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples are conventional biochemical reagents unless otherwise specified; the experimental methods are conventional methods unless otherwise specified.

The present invention will be described in detail below in conjunction with the embodiments.

Example 1

(1) 4.9376g of high-purity urea was added to the round-bottomed flask to which 10.2411g of high-purity water had been added, after sealing with a grinding plug, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 2.5629 g of ethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 1.1335 g of methanol to the solution obtained in step (2), seal it with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

After measurement, the freezing point of the mixture solution is -18°C, the surface tension is 70.3mN/m, the conductivity is 555μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 2

(1) 5.0335g of high-purity urea was added to the round-bottomed flask to which 10.4505g of high-purity water had been added, and after sealing with a grinding plug, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 2.626 g of ethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 2.6200 g of methanol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) pressure filtering the solution obtained in step (3) with a filter element having a filtration precision of 0.8 pm, to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

After measurement, the freezing point of the mixture solution is -24°C, the surface tension is 65.5mN/m, the conductivity is 449μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride are The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 3

(1) 5.0342g of high-purity urea was added to the round-bottomed flask to which 10.4476g of high-purity water had been added, and after sealing with a grinding plug, the water bath was heated to 40°C, and the magnetic stirring was performed until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 2.6135 g of ethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 4.4703 g of methanol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

After measurement, the freezing point of the mixture solution is -28°C, the surface tension is 60.3mN/m, the conductivity is 380μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 4

(1) 4.9765g of high-purity urea was added to the round-bottomed flask to which 10.3377g of high-purity water had been added, and after sealing with a grinding plug, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 2.5896 g of ethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 6.898 g of methanol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

It has been determined that the freezing point of the mixture solution is -32°C, the surface tension is 57.3mN/m, the conductivity is 299μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride are The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being treated by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 5

(1) 10.3200g of high-purity urea was added to the round-bottomed flask to which 21.4329g of high-purity water had been added, and after sealing with a ground stopper, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 5.3551 g of ethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 5.3610 g of ethanol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

After measurement, the freezing point of the mixture solution is -26°C, the surface tension is 54.0mN/m, the conductivity is 316μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride are The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 6

(1) 9.2948g of high-purity urea was added to the round-bottomed flask to which 19.3036g of high-purity water had been added, and after sealing with a grinding plug, the water bath was heated to 40°C, and the magnetic stirring was performed until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 4.8283 g of ethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 8.2698 g of ethylene glycol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed evenly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

It has been determined that the freezing point of the mixture solution is -32°C, the surface tension is 63.8mN/m, the conductivity is 470.5μS/cm, the appearance is clear and transparent, and the product quality index meets the requirements of ISO 22241-I:2006 international standards, and carbonate and chlorine The detection amount of the chemical conforms to the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 7

(1) 11.0341g of high-purity urea was added to the round-bottomed flask to which 22.9221g of high-purity water had been added, and after sealing with a grinding plug, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 5.6311 g of diethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 9.8861 g of methanol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

It has been determined that the freezing point of the mixture solution is -35°C, the surface tension is 55.9mN/m, the conductivity is 183μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 8

(1) 9.9590g of high-purity urea was added to the round-bottomed flask to which 20.6847g of high-purity water had been added, and after sealing with a grinding plug, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 5.1768 g of diethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 5.1719 g of ethanol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

It has been determined that the freezing point of the mixture solution is -27°C, the surface tension is 52.7mN/m, the conductivity is 212μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

Example 9

(1) 11.6944g of high-purity urea was added to the round-bottomed flask to which 24.2808g of high-purity water had been added, and after sealing with a grinding plug, heated to 40°C in a water bath, and magnetically stirred until the urea was completely dissolved, and the solution was transparent;

(2) Cool the solution obtained in step (1) to room temperature, add 6.0732 g of diethanolamine, seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(3) Add 10.4111 g of ethylene glycol to the solution obtained in step (2), seal with a grinding plug, and stir magnetically until the solution is completely mixed uniformly.

(4) The solution obtained in step (3) is filtered with a filter element pressure with a filtration precision of 0.8 pm and 0.6 MPa to obtain the urea solution for diesel vehicles with low temperature performance of the present invention.

After measurement, the freezing point of the mixture solution is -31°C, the surface tension is 62.3mN/m, the conductivity is 210μS/cm, the appearance is clear and transparent, the product quality index meets the requirements of ISO 22241-I:2006 international standard, and carbonate and chloride are The detected amount complies with the DB11/552-2008 Beijing standard; after three months of sealed storage at room temperature, there is no sensory change in appearance and smell.

The product of this embodiment is tested under ETC and ESC working conditions on a diesel engine bench with a power of 233 horsepower (displacement 6.5L). Under the rated injection volume of the product, after being processed by the SCR post-treatment system, the NOx emission can reach the national four. standard.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (9)

1. A urea solution with low temperature performance for diesel vehicles is characterized in that: consists of a component A, a component B, a component C and a component D; the component A is high-purity water, the component B is urea, the component C is ethanolamine and/or diethanolamine, and the component D is a micromolecular liquid alcohol substance;

the weight parts of the components are as follows: 40-70 parts of a component A, 20-35 parts of a component B, 5-25 parts of a component C and 5-40 parts of a component D.

2. The urea solution for diesel vehicles having low temperature properties according to claim 1, characterized in that: the weight parts of the components are as follows: 45-65 parts of a component A, 23-30 parts of a component B, 8-22 parts of a component C and 9-35 parts of a component D.

3. The urea solution for diesel vehicles having low temperature properties according to claim 1, characterized in that: the weight parts of the components are as follows: 50-60 parts of a component A, 25-28 parts of a component B, 13-20 parts of a component C and 15-28 parts of a component D.

4. Urea solution according to any of the claims 1-3 for diesel vehicles having low temperature properties, characterized in that: the content of the component C is 20 parts.

5. Urea solution according to any of the claims 1-3 for diesel vehicles having low temperature properties, characterized in that: the component D is one or more than two of methanol, ethanol and glycol.

6. A process for the preparation of a urea solution for diesel vehicles having low temperature properties according to any one of claims 1 to 5, characterized in that: the method comprises the following steps:

(1) adding the component B into the component A, and fully dissolving the component B to obtain a transparent solution;

(2) and (2) sequentially adding the component C and the component D into the transparent solution in the step (1), fully stirring and uniformly mixing, and obtaining a mixed solution to obtain the urea solution with low temperature performance for the diesel vehicle.

7. The process for preparing a urea solution for diesel vehicles having low temperature properties according to claim 6, characterized in that: and (2) sequentially adding the component C and the component D into the transparent solution obtained in the step (1), fully stirring and uniformly mixing, and filtering the obtained mixed solution to obtain the urea solution with low temperature performance for the diesel vehicle.

8. The method for preparing urea solution for diesel vehicles with low temperature performance as claimed in claim 7, wherein: and (3) filtering the mixed solution in the step (2) by using a filter element with the pressure of 0.5-0.8 mu m and 0.6Mpa to obtain the urea solution with low temperature performance for the diesel vehicle.

9. The method for preparing urea solution for diesel vehicles with low temperature performance as claimed in claim 6, wherein: in the step (1), the component B is added into the component A and fully dissolved at the temperature of 35-40 ℃ to obtain a transparent solution; in the step (2), after the transparent solution in the step (1) is cooled to room temperature, the component C is added, and after the component C is completely dissolved, the component D is added.