KR20240036811A - NOx reducing agent including ammonium formate, ammonium acetate or mixtures thereof, exhaust gas purification apparatus including the same, and method for reducing NOx using the same - Google Patents

Abstract

The present invention relates to a NOx reducer containing ammonium formate, ammonium acetate, or a mixture thereof, an exhaust gas purification device containing the same, and a method for reducing NOx using the same. By-products are deposited even when the exhaust temperature of a vehicle is lowered. It can show excellent performance with NOx reducers that do not work.

Description

NOx reducing agent including ammonium formate, ammonium acetate or mixtures thereof, exhaust gas purification apparatus including same, and method for reducing NOx using the same {NOx reducing agent including ammonium formate, ammonium acetate or mixtures thereof, exhaust gas purification apparatus including the same, and method for reducing NOx using the same}

The present invention relates to a NOx reducing agent containing ammonium formate, ammonium acetate, or a mixture thereof, an exhaust gas purification device containing the same, and a method for reducing NOx using the same.

Urea water is a liquid chemical substance with a 32.5% urea content made by mixing urea, the raw material for urea fertilizer, and pure water. This urea water is used to purify nitrogen oxides (NOx) in diesel engine vehicles. Nitrogen oxides (NOx) are air pollutants known to cause various respiratory diseases such as bronchitis and pneumonia and are the main cause of optical smog and acid rain.

The technology to purify nitrogen oxides (NOx) using urea water is called Urea-SCR, and is also called DEF (Diesel Exhaust Fluid) in the United States and AdBlue in Europe. The Urea-SCR system purifies nitrogen oxides (NOx) in the exhaust gas by injecting urea water through a urea water injection device while the exhaust gas generated from a diesel engine passes through the SCR catalyst system.

In manufacturing the urea water used in the Urea-SCR system, the conventional method was to supply heat to dissolve the urea. In order to apply this method, an increase in additional equipment such as heating equipment was inevitable. There is a disadvantage in that the urea solution manufacturing device has to be enlarged overall, which reduces efficiency, and the resulting increase in manufacturing cost reduces economic feasibility.

In addition, when diesel engine vehicles that use urea are driven at low to medium speeds and low rpm for a long period of time, or when driven in seasons when the vehicle exhaust temperature is low, urea may accumulate on the exhaust pipe and SCR catalyst system, and residue may remain. As a result, the reduction efficiency of nitrogen oxides (NOx) decreases due to poisoning of the SCR catalyst, causing the vehicle engine to operate in a restricted mode and causing frequent breakdowns.

In the mid- to long-term, emissions of soot, nitrogen oxides (NOx), and fine dust are recognized as serious problems in the case of internal combustion engine vehicles that use fossil fuels such as gasoline or diesel, especially diesel vehicles such as buses and trucks, and research into this is needed.

Japanese Patent Publication 2004-290835 A Japanese Patent Publication 2002-530575 A

The purpose of the present invention is to provide a NOx reducer containing ammonium formate, ammonium acetate, or a mixture thereof, which has no by-products at low speeds and has excellent nitrogen content and dissolution performance.

Another object of the present invention is to provide an exhaust gas purification device containing the NOx reducing agent and a method for reducing NOx using the same, and an exhaust gas purification device with excellent performance that does not accumulate by-products even when the exhaust temperature of the vehicle is lowered. and methods are provided.

The present invention relates to ammonium formate, ammonium acetate, or mixtures thereof; and one or more auxiliary additives selected from guanidine, guanidine acetate, guanidine formate, ammonium oxalate, and ammonium tartrate.

The ammonium formate, ammonium acetate, or a mixture thereof may be included in an amount of 30 to 90% by weight based on the total NOx reducer.

The auxiliary additive may be included in an amount of 1 to 30% by weight based on the total NOx reducer.

The NOx reducing agent according to an embodiment of the present invention may be characterized as containing 16 to 45% by weight of nitrogen, and the freezing point of the NOx reducing agent may be -15°C to -35°C.

The present invention provides an exhaust gas purification device including a NOx reducing agent according to an embodiment, the exhaust gas purification device comprising:

Selective reduction (SCR) catalyst connected to the exhaust pipe;

a tank located between the exhaust pipe and the SCR catalyst and containing a NOx reducing agent;

A spray unit that sprays the NOx reducing agent in the tank;

Sensors located upstream and downstream of the SCR catalyst and measuring NOx concentration; and

It may include a controller that controls the injection amount of the injection unit.

In addition, the present invention provides a method for reducing NOx by contacting exhaust gas with a NOx reducing agent according to an embodiment, and the method for reducing NOx

A step of spraying a NOx reducing agent into a pipe where an exhaust gas flow exists and contacting the exhaust gas; and

It may include the step of reducing nitrogen oxides contained in the exhaust gas flow in the presence of an SCR catalyst.

The NOx reducing agent of the present invention is environmentally friendly because it can reduce nitrogen oxides (NOx) like existing urea water even in low-speed driving and low-temperature environments, and is very economical because it does not cause breakdowns due to urea water stacking on the exhaust pipe and SCR catalyst. As an alternative material, it can exhibit excellent performance.

Figure 1 is a diagram showing an exhaust gas purification device and reaction schematic diagram of a NOx reducing agent.

Hereinafter, a NOx reducing agent containing ammonium formate, ammonium acetate, or a mixture thereof of the present invention, an exhaust gas purification device containing the same, and a method for reducing NOx using the same will be described in detail.

As used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms, unless the context clearly dictates otherwise.

In addition, the numerical range used in the present invention includes the lower limit and upper limit and all values within the range, increments logically derived from the shape and width of the defined range, all double-defined values, and the upper limit of the numerical range defined in different forms. and all possible combinations of the lower bounds. Unless otherwise specified in the specification of the present invention, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

As used in the present invention, “comprises” is an open description with the same meaning as expressions such as “comprises,” “contains,” “has,” or “characterized by” elements that are not additionally listed; Does not exclude materials or processes.

The nitrogen oxides or NOx described in the present invention are meant to include both nitrogen monoxide (NO) and nitrogen dioxide (NO ₂ ).

Hereinafter, the present invention will be described in detail. At this time, if there is no other definition in the technical and scientific terms used, they have meanings commonly understood by those skilled in the art to which this invention pertains, and the following description will not unnecessarily obscure the gist of the present invention. Descriptions of possible notification functions and configurations are omitted.

To purify nitrogen oxides (NOx) emitted from automobiles, a urea-selective catalytic reaction system (UREA-SCR: Urea-Selective Catalyst Reduction) is applied. This method uses various sensors such as the NOx sensor and a urea injection control device to control the exhaust pipe. This is a method in which urea water is precisely sprayed inside, and the sprayed urea water is thermally decomposed by the heat of the exhaust gas and converted into ammonia. Subsequently, ammonia reacts with NOx in the SCR catalyst and decomposes into water and nitrogen, thereby reducing NOx. This process is shown in Figure 1.

Urea is a liquid chemical used in NOx reduction devices (SCR) for diesel vehicles. When the urea concentration is 32.5%, the freezing point is the lowest at -11°C, so when setting standards, the urea solution for automobiles is 32.5%. It is set as %. Conventional urea water for automobiles had the problem of freezing at temperatures below -11°C, and the above problem can be solved by replacing the conventional urea water with the NOx reducer according to an embodiment of the present invention.

The present invention relates to ammonium formate, ammonium acetate, or mixtures thereof; and one or more auxiliary additives selected from guanidine, guanidine acetate, guanidine formate, ammonium oxalate, and ammonium tartrate. The ammonium formate and ammonium acetate are shown in Chemical Formulas 1 and 2 below.

[Formula 1]

[Formula 2]

In one embodiment of the present invention, the auxiliary additive may preferably be guanidine, guanidine acetate, or guanidine formate, and more preferably may be guanidine acetate or guanidine formate.

The ammonium formate, ammonium acetate, or a mixture thereof may be included in an amount of 30 to 90% by weight, specifically 35 to 80% by weight, and more specifically 40 to 70% by weight, based on the total NOx reducing agent.

The auxiliary additive may be included in an amount of 1 to 30% by weight, specifically 2 to 25% by weight, and more specifically 3 to 20% by weight, based on the total NOx reducer.

The NOx reducing agent according to an embodiment of the present invention may be characterized as containing 16 to 45% by weight of nitrogen, preferably 17 to 43% by weight, and more preferably 18 to 40% by weight. there is.

Additionally, the freezing point of the NOx reducing agent according to an embodiment of the present invention may be -15 to -35 °C, preferably -20 to -35 °C, and more preferably -25 to -35 °C.

The present invention provides an exhaust gas purification device including a NOx reducing agent according to an embodiment, the exhaust gas purification device comprising:

Selective reduction (SCR) catalyst connected to the exhaust pipe;

a tank located between the exhaust pipe and the SCR catalyst and containing a NOx reducing agent;

A spray unit that sprays the NOx reducing agent in the tank;

Sensors located upstream and downstream of the SCR catalyst and measuring NOx concentration; and

It may include a controller that controls the injection amount of the injection unit.

The selective reduction (SCR) catalyst may include a transition metal or transition metal oxide, specifically vanadium oxide, tungsten oxide, titanium oxide, iron oxide, manganese oxide, chromium oxide, copper oxide, zeolite, platinum, palladium, rhodium. and iridium, but are not limited thereto.

In addition, the present invention provides a method for reducing NOx by contacting exhaust gas with a NOx reducing agent according to an embodiment, and the method for reducing NOx

A step of spraying a NOx reducing agent into a pipe where an exhaust gas flow exists and contacting the exhaust gas; and

It may include the step of reducing nitrogen oxides contained in the exhaust gas flow in the presence of an SCR catalyst.

The exhaust gas in which NOx needs to be reduced may contain 100 to 1100 ppm of NOx. By using the method for reducing NOx including a NOx reducing agent according to an embodiment of the present invention, the NOx content can be reduced by 30 to 99%, and preferably, the NOx content can be reduced by 50 to 99%.

Hereinafter, the NOx reducing agent containing ammonium formate, ammonium acetate, or a mixture thereof according to the present invention, the exhaust gas purification device containing the same, and the method for reducing NOx using the same will be described in more detail through specific examples. do.

[Preparation Example 1] Preparation of ammonium formate

40.98 ml (1.086 mol) of formic acid was placed in a 250 ml beaker, a thermometer and stirrer were installed, and 140.77 ml (1.086 mol) of 30% aqueous ammonia was slowly added dropwise. Stir for 2 hours while maintaining the temperature at room temperature using an ice bath. Water is removed using a reduced pressure evaporator, and the precipitated white solid is filtered. The precipitated solid was filtered, the remaining material was washed with ethanol, and then dried using a reduced pressure dryer to prepare ammonium formate in Preparation Example 1 (yield 90%).

[Preparation Example 2] Preparation of NOx reducing agent-1 (ammonium formate aqueous solution)

Add 409.8 ml (10.86 mol) of formic acid to a 2L beaker, install a thermometer, stir, and ice bath, and slowly add 1407.7 ml (10.86 mol) of 30% aqueous ammonia dropwise to adjust the pH of the reaction solution to 6 to 7. Accordingly, Preparation Example 2 ammonium formate aqueous solution was prepared.

[Preparation Example 3] Preparation of ammonium acetate

Acetic acid (94.8 ml (1.66 mol)) was added to a 250 ml beaker, a thermometer, stirrer, and ice bath were installed, and 215 ml (1.66 mol) of 30% ammonia water was slowly added dropwise. Stir for 2 hours while maintaining the temperature at room temperature using an ice bath. Water is removed using a reduced pressure evaporator, and the precipitated white solid is filtered. The precipitated solid was filtered, the remaining material was washed with ethanol, and then dried using a reduced pressure dryer to prepare ammonium acetate in Preparation Example 3 (yield 85%).

[Preparation Example 4] Preparation of NOx reducing agent-2 (ammonium acetate aqueous solution)

Add 445.71 ml (7.8 mol) of acetic acid to a 2 L beaker, install a thermometer, stir, and ice bath, and slowly add 1011.11 ml (7.8 mol) of 30% aqueous ammonia dropwise to adjust the pH of the reaction solution to 6 to 7. An ammonium acetate aqueous solution was prepared accordingly.

[Preparation Example 5] Preparation of guanidine formate aqueous solution

An aqueous solution of guanidine formate in Preparation Example 5 was prepared in the same manner as in Preparation Example 2, except that 1037.1 g (10.86 mol) of guanidine dissolved in 2,000 ml of water was used instead of aqueous ammonia.

[Preparation Example 6] Preparation of guanidine acetate aqueous solution

An aqueous guanidine acetate solution of Preparation Example 6 was prepared in the same manner as Preparation Example 4, except that a solution of 744.9 g (7.8 mol) of guanidine in 1,500 ml of water was used instead of aqueous ammonia.

[Example 1] Preparation of NOx reducing agent-3

Example 1 was prepared by mixing 900 ml of Preparation Example 2 and 100 ml of Preparation Example 5.

[Example 2] Preparation of NOx reducing agent-4

Example 1 was prepared by mixing 900 ml of Preparation Example 4 and 100 ml of Preparation Example 6.

[Experimental Example 1] Nitrogen content analysis of NOx reducing agent

The theoretical nitrogen contents of Preparation Examples 2, 4, 5, and 6 were calculated, and the results are shown in Table 1 below.

Production example 2 Production example 4 Production example 5 Production example 6 Nitrogen content (%) 22.22 18.18 40.01 35.29

As shown in Table 1, the nitrogen content of Preparation Examples 2, 4, 5, and 6 was all analyzed to be 18% or more, confirming that the nitrogen content is suitable as a NOx reducer. [Experimental Example 2] Freezing point evaluation

The freezing points of Preparation Example 2, Preparation Example 4, Example 1, and Example 2 were measured and shown in Table 2.

Production example 2 Production example 4 Example 1 Example 2 Freezing point (℃) -29 -28 -31 -32

As shown in Table 2, it can be confirmed that Preparation Examples 2 and 4, which are the NOx reducers of the present invention, show a significantly improved freezing point of -28 to -29 ℃ compared to the freezing point of existing urea solution of -11 ℃, Example 1 and 2 showed a freezing point of -31 to -32°C, which was much lower than this. As a result, it can be seen that the NOx reducer of the present invention has a significantly lower freezing point and has excellently improved physical properties.

Therefore, the NOx reducing agent of the present invention can reduce NOx like existing urea water even in low-speed driving and low-temperature environments, and can be a NOx reducing agent that exhibits excellent physical properties that do not cause failure due to stacking of urea water on exhaust pipes and SCR catalysts. there is. The NOx reducing agent according to an embodiment of the present invention has excellent solubility, exhibits improved dispersibility in water or organic solvents, and also has excellent dispersion stability. In particular, it has high solubility and dispersibility in polar solvents such as water, alcohol, or mixtures thereof, resulting in significantly improved storage stability.

As described above, the present invention has been described with specific details and limited examples and comparative examples, but these are provided only to facilitate a more general understanding of the present invention, and the present invention is not limited to the above-mentioned examples. Those skilled in the art can make various modifications and variations from this description.

Accordingly, the spirit of the present invention should not be limited to the described embodiments, and the scope of the patent claims described below as well as all modifications that are equivalent or equivalent to the scope of this patent claim shall fall within the scope of the spirit of the present invention. .

Claims (9)

Ammonium formate, ammonium acetate, or mixtures thereof; and one or more auxiliary additives selected from guanidine, guanidine acetate, guanidine formate, ammonium oxalate, and ammonium tartrate. According to paragraph 1,
A NOx reducing agent containing 30 to 90% by weight of the ammonium formate, ammonium acetate, or a mixture thereof based on the total NOx reducing agent. According to paragraph 1,
The NOx reducing agent contains 1 to 30% by weight of the auxiliary additive based on the total NOx reducing agent. According to paragraph 1,
The NOx reducing agent is characterized in that it contains 16 to 45% by weight of nitrogen. According to paragraph 1,
The NOx reducing agent has a freezing point of -15 to -35°C. An exhaust gas purification device comprising the NOx reducing agent of any one of claims 1 to 5. According to clause 6,
The exhaust gas purification device,
Selective reduction (SCR) catalyst connected to the exhaust pipe;
a tank located between the exhaust pipe and the SCR catalyst and containing a NOx reducing agent;
A spray unit that sprays the NOx reducing agent in the tank;
Sensors located upstream and downstream of the SCR catalyst and measuring NOx concentration; and
a controller that controls the injection amount of the injection unit;
Including, an exhaust gas purification device. A method of reducing NOx by contacting exhaust gas with the NOx reducing agent according to any one of claims 1 to 5. According to clause 8,
The method for reducing NOx is,
A step of spraying a NOx reducing agent into a pipe where an exhaust gas flow exists and contacting the exhaust gas; and
Reducing nitrogen oxides contained in the exhaust gas flow in the presence of an SCR catalyst;
Method for reducing NOx, including.