KR20120102381A - Liquid fuel composition with improved thermal stability - Google Patents

Abstract

PURPOSE: A liquid fuel composition is provided to improve the thermal stability of exo-tetrahydrodicyclopentadiene(exo-THDCP) by adding a thermal stabilizer into the exo-THDCP. CONSTITUTION: A liquid fuel composition includes exo-THDCP as liquid fuel and a thermal stabilizer. 0.1 to 5.0 weight% of one or more selected from tetrahydroquinoline, benzyl alcohol, and tetrahydroquinoxaline is added into the exo-THDCP as the thermal stabilizer. The tetrahydroquinoline is represented by chemical formula 2. In chemical formula 2, R1 is CH_2; n is 2 or 3; and R2 is H, CH_3, or C_2H_5. The tetrahydroquinoxaline is represented by chemical formula 4. In chemical formula 4, R1 is H, CH_3, or C_2H_5; and R2 is H, CH_3, or C_2H_5.

Description

Liquid fuel composition with improved thermal stability

The present invention relates to a liquid fuel composition having improved thermal stability by adding a heat stabilizer to exo-tetrahydrodicyclopentadiene (EXO-THDCP) which can be used as a liquid fuel.

As aircraft and rocket technology moves at supersonic speeds, the fuels used in the aircrafts are deformed by the frictional heat generated when the projectile flies above the supersonic speed and the heat generated by the engines and controls inside the projectile. A problem arises. In addition, if the fuel is denatured due to the high temperature and high pressure conditions inside the projectile, the chemical structure may be changed, the physical properties may be changed, and the fuel performance may be degraded. Also, tar may be easily formed due to fuel decomposition, causing problems in fuel system clogging. The fuel requires stability to pyrolysis at high temperatures as it can lead to malfunction of the system in severe cases.

There is a method of using insulation to control the rise of the temperature of the fuel, but it is not enough to solve many thermal loads, and there is a disadvantage of increasing the weight of the propulsion engine, so in recent years, the method of using the fuel as a coolant is an effective measure. In this case, the thermal stability of the fuel should be maintained at high temperatures. Thermal stability generally means that the decomposition of the initial chemical components of the fuel does not occur at high temperatures, and can be evaluated by the temperature at which decomposition starts, the decomposition rate with time at high temperatures, or the degree of deposit formation by decomposition.

Prior art US Pat. Nos. 7,589,243 and 7,671,245 to improve the thermal stability of fuels refer to the use of thermal stability improvers apart from antioxidants as additives in kerosene type jet fuel compositions, with a content of 0.001 Although 5% by weight is described as possible, there is no mention of a detailed composition.

In addition, U.S. Patent No. 4,330,302 suggests that quinoline is possible as a compound containing nitrogen as an additive for improving the thermal stability of kerosine jet fuel.

Also in foreign literature (Emily M. Yoon et al, "High-Temperature Stabilizers for Jet Fuels and Similar Hydrocarbon Mixtures. 1. Comparative Studies of Hydrogen Donors", Energy & Fuels 1996, 10, 806-811). The effects and mechanism of action of tetrahydroquinoline (THQ) as an additive for improving thermal stability were presented.

Single component exo-THDCP starts to decompose at 370 ° C in the absence of a thermal stability enhancer, and the decomposition rate increases with increasing temperature, keeping 10% of exo-THDCP at 380 ° C, 20% at 390 ° C, and At 400 ° C., 35% is decomposed and changed into other materials, so the fuel properties and properties are changed, thereby degrading the performance of the fuel, and also having a serious problem in that it cannot function as a coolant that absorbs heat at high temperatures.

In order to improve the phenomena and maintain fuel performance at high temperatures, the decomposition rate of exo-THDCP should be lowered. However, only some compounds such as THQ are known as kerosine type jet fuel additives, and mixed with other functional additives. The product was managed in the form of a package, so the exact composition could not be confirmed.

Therefore, studies on the improvement of thermal stability of exo-THDCP using additives have not been actively conducted, and the results of the studies have not been reported. As the use of exo-THDCP at high temperatures increases with the recent development of high-speed aircraft, Improvement of thermal stability was urgent.

It is an object of the present invention to provide a liquid fuel composition having improved thermal stability by adding a specific thermal stability enhancer to exo-THDCP usable as a liquid fuel.

The liquid fuel composition of the present invention is one selected from tetrahydroquinoline (THQ), benzyl alcohol (BnOH) and tetrahydroquinoxaline (THQox) as a heat stabilizer for exo-THDCP. Or it consists of two or more, the thermal stability improver is characterized in that it comprises 0.1 to 5.0% by weight based on the total weight of the composition.

Exo-THDCP (exo-tetrahydrodicyclopentadiene, C ₁₀ H ₁₆ ) used in the present invention has a structure as shown in Formula 1 below, low toxicity, moderate ignition temperature (55 ℃), high volume energy (39.6MJ / liter ) And excellent physicochemical properties, as well as low-cost production, it is widely used as a cleaning agent for semiconductors, diluents of surfactants, lubricants, cutting oils, etc. in addition to special liquid fuels.

[Formula 1]

The structures of THQ, BnOH and THQox used as thermal stability enhancers in the present invention are as shown in [Formula 2], [Formula 3] and [Formula 4], respectively.

[Formula 2]

(여기에서, R1=CH₂, n=2 또는 3, R2=H, CH₃ 또는 C₂H₅)

Where R 1 = CH ₂ , n = 2 or 3, R 2 = H, CH ₃ or C ₂ H ₅

(3)

(여기에서, R1=CH₂OH, R2=H 또는 CH₂OH)

Wherein R 1 = CH ₂ OH, R ₂ = H or CH ₂ OH

[Formula 4]

(여기에서, R1=H, CH₃ 또는 C₂H₅, R2=H, CH₃ 또는 C₂H₅)

Where R 1 = H, CH ₃ or C ₂ H ₅ , R ₂ = H, CH ₃ or C ₂ H ₅

When using 2 or more types of said thermal stability improvers, there is no restriction | limiting in particular in the mixing ratio, For example, it is preferable to mix in the same weight ratio.

In the liquid fuel composition of the present invention, the content (total amount) of the heat stabilizer is preferably 0.1 to 5.0% by weight, and preferably 0.1 to 0.5% by weight when the total amount of the liquid fuel composition is 100% by weight. More preferred. If the content is less than 0.1% by weight, it is not preferable because the thermal stability effect by the additive is not large, and when the content exceeds 5.0% by weight, the thermal stability effect by the additive increases, but it affects other physical properties such as deterioration of fuel performance. Is not preferred.

The liquid fuel composition of the present invention can improve the thermal stability of exo-THDCP by mixing one or two or more selected from THQ, BnOH and THQox as a thermal stability enhancer to exo-THDCP usable as a liquid fuel.

1 is a structural diagram of a thermal stability test apparatus used in Examples and Comparative Examples of the present invention,
Figure 2 shows the results of thermal stability analysis according to Examples and Comparative Examples of the present invention, 0.1 wt% of BnOH, THQ, BnOH + THQ (weight ratio = 1: 1), THQox was added to exo-THDCP as a thermal stability enhancer, respectively. It is a graph showing that the decomposition rate and total decomposition rate of exo-THDCP at 390 ℃ is reduced compared to the case without addition of the thermal stability enhancer,
FIG. 3 shows the results of thermal stability analysis according to Examples and Comparative Examples of the present invention, wherein 0.5 wt% of BnOH, THQ, BnOH + THQ (weight ratio = 1: 1), and THQox were respectively added to exo-THDCP as a thermal stability enhancer. It is a graph showing that the decomposition rate and total decomposition rate of exo-THDCP at 390 ℃ is reduced compared to the case without addition of the thermal stability enhancer,
Figure 4 is a thermal stability analysis results according to the comparative example, a graph showing a comparison result of the decomposition of exo-THDCP with temperature in a state of maintaining the nitrogen pressure 45bar,
5 is a thermal stability analysis result according to the comparative example, the color of exo-THDCP according to the temperature of 380 ℃ (a), 390 ℃ (b), 400 ℃ (c) at a nitrogen pressure of 45bar It is a graph showing the result of comparison of change.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. The following examples are merely examples for carrying out the present invention, and are not intended to limit the protection scope of the present invention.

Examples and Comparative Examples

1. Experimental conditions

Thermal stability was evaluated by analyzing the thermal decomposition rate of each liquid fuel composition of Example and Comparative Example using the test apparatus shown in FIG.

1 shows a thermal stability test apparatus for the liquid fuel composition. Here, the batch reactor 6 is made of stainless steel 316 at an available pressure of 200 bar, or a quartz flask is mounted therein to exclude the influence of the reactor material. In addition, it is composed of a nitrogen pressurization device (1, 2) for maintaining the liquid state of the fuel in the reactor at a high temperature, and a heating jacket (8) that can be heated outside the reactor to increase the internal temperature. Condensation tank (9) and collector (10), and gas phase product separator (11), which can collect samples in real time during the reaction, and GC / MS (Quality Analysis and Quantitative Analysis) (Agilent 5975C, column: HP-) 5ms) is connected. The thermal stability test apparatus shown in FIG. 3 may further include other equipment not shown in FIG. 1 as needed.

In the thermal stability evaluation experiment preparation, the liquid fuel composition was prepared by completely dissolving each component in the weight ratio shown in Table 1 before the experiment, and foreign substances that may affect the reaction through the washing operation on the reactor and the line. Etc. was minimized.

Inject 100 mL of each prepared liquid fuel composition into a batch reactor (160 mL), and pressurized to 45 bar using N ₂ , gradually heating the heating jacket around the reactor to increase the temperature inside the reactor, and then at this temperature. The reaction was carried out for a total of 10.5 hours, 1mL of fuel was extracted at 90 minutes interval during the reaction, and qualitative and quantitative analysis of the composition and composition of exo-THDCP and decomposition products by GC-MS Was carried out.

In the component analysis, the spectral peaks of the corresponding components in the mass detector did not correspond more than two of the main peaks in the mass detector library.

Through the above experimental results, the thermal stability of exo-THDCP was evaluated based on the degree of difference between the conversion rate and the rate of exo-THDCP to other materials by pyrolysis depending on the type of thermal stability enhancer.

Comparative Examples and liquid fuel compositions and test conditions for each example are shown in Table 1 below, and specific contents of the thermal stability improver used are shown in Table 2 below.

2. Experimental results

Comparative Example 1

As a result of the thermal stability test of the liquid fuel of Comparative Example 1, the conversion rate (decomposition rate) exo-THDCP is converted to the decomposition material was confirmed, and the results at 390 ° C are shown in Table 3 below and FIGS. 2 and 3, and 370 to 400 The overall results at ° C are shown in FIG. 4 as a graph of undecomposed residual amount, and the color change of the fuel is shown in FIG. 5.

As shown in Figure 4, the exo-THDCP of a single component without a thermal stability improver starts the decomposition at 370 ℃, the decomposition rate increases with increasing temperature, 10% by weight of exo-THDCP when maintained for 10.5 hours at 380 ℃, At 390 ° C., 19.5% by weight, and at 400 ° C., 35% by weight are pyrolyzed to change to other materials. As shown in FIG. 5, the color is changed according to the degree of thermal decomposition.

Examples 1-8

As a result of the thermal stability test of the liquid fuel mixed with the thermal stability improver at 390 ° C. as shown in Examples 1 to 8 of Table 1, the conversion rate (decomposition rate) at which exo-THDCP is converted into a decomposition material was determined. 3 and shown in FIGS. 2 and 3.

As can be seen from Table 3 and Figure 2, according to Examples 1 to 4 of the present invention, the thermal stability enhancer of each of the BnOH, THQ, BnOH + THQ (weight ratio 1: 1 mixture), THQox according to the present invention When 0.1 wt% of each was added, it was found that the hourly decomposition rate and total decomposition rate of exo-THDCP were significantly reduced compared to Comparative Example 1, which is a result of not using a thermal stability enhancer.

And as can be seen from Table 3 and Figure 3, according to Examples 5 to 8 of the present invention, the thermal stability enhancer of each BnOH, THQ, BnOH + THQ (weight ratio 1: 1 mixture), THQox according to the present invention When 0.5 wt% of each of the exo-THDCP degradation rate and total decomposition rate of the time was found to be further reduced compared to Examples 1 to 4 as a result of adding 0.1% by weight of each of the thermal stability enhancer described above.

Therefore, in Examples 1 to 8 of the present invention, each of the thermal stability enhancers of BnOH, THQ, BnOH + THQ (weight ratio 1: 1 mixture) and THQox proposed by the present invention was added in an amount of exo- by 0.1 to 0.5% by weight, respectively. It was confirmed that the thermal stability of exo-THDCP is improved since the time-dependent decomposition rate and total decomposition rate of THDCP are significantly reduced compared to Comparative Example 1, which is a result of not using the thermal stability enhancer.

Claims (5)

It comprises a liquid fuel exo-tetrahydrodicyclopentadiene (exo-THDCP) and a heat stability improver, tetrahydroquinoline (THQ), benzyl alcohol (BnOH) and tetrahydroquinoxaline (THQox) as the heat stability enhancer A liquid fuel composition comprising one or two or more selected from the group consisting of 0.1 to 5.0% by weight based on the total weight of the composition. The liquid fuel composition of claim 1, wherein the thermal stability enhancer comprises 0.1 to 0.5% by weight based on the weight of the total composition. According to claim 1, wherein the tetrahydroquinoline is a liquid fuel composition, characterized in that represented by the formula (2).
(2)

Where R 1 = CH ₂ , n = 2 or 3, R 2 = H, CH ₃ or C ₂ H ₅ According to claim 1, wherein the benzyl alcohol is a liquid fuel composition, characterized in that represented by the formula (3).
(3)

Wherein R 1 = CH ₂ OH, R ₂ = H or CH ₂ OH According to claim 1, wherein the tetrahydroquinoxaline is a liquid fuel composition, characterized in that represented by the formula (4).
[Chemical Formula 4]

Where R 1 = H, CH ₃ or C ₂ H ₅ , R ₂ = H, CH ₃ or C ₂ H ₅

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