KR101022818B1 - Process for eliminating nitrogen-containing compounds from hydrocarbons using zinc-containing imidazolium type ionic liquids - Google Patents

Abstract

The present invention relates to a method for the easy and economical removal of nitrogen compounds from hydrocarbon fractions including fuel oils using imidazolium-based ionic liquids containing zinc. The imidazolium-based ionic liquid containing zinc according to the present invention can remove nitrogen compounds, especially aromatic nitrogen compounds, contained in petroleum hydrocarbon fractions very efficiently through a simple extraction process.

Imidazolium ionic liquid, zinc, nitrogen compound, hydrocarbon oil

Description

Process for removing nitrogen compounds from hydrocarbon fractions using zinc-containing imidazolium-based ionic liquids

The present invention relates to a method for removing nitrogen compounds from hydrocarbon fractions using an imidazolium-based ionic liquid containing zinc. More specifically, the present invention relates to a method for easily and economically removing nitrogen compounds from various petroleum hydrocarbon fractions, including fuel oils, using an imidazolium-based ionic liquid containing zinc.

Recently, due to the environmental pollution caused by SOx and NOx, regulations on the sulfur and nitrogen content in petrochemical products, especially fuel oil, have been tightened around the world. It is rising.

Sulfur and nitrogen compounds contained in fuel oils such as gasoline and diesel fuel not only cause environmental pollutants such as SOx and NOx to be emitted into the atmosphere during combustion, but also act as catalyst poisons for automobile exhaust gas reducing devices. In addition, since nitrogen compounds and sulfur compounds included in the hydrocarbon fraction in the middle stage of the petroleum refining process poison the catalyst used in the cracking or reforming process, the reaction efficiency is reduced and the catalyst life is shortened. There has been extensive research to remove compounds.

Hydrogen desulfurization and dehydrogenation are the most commonly used industrial methods to reduce the sulfur and nitrogen content in the refining process.However, the desulfurization and denitrification by hydrogenation is a complex process and consumes a lot of energy. In addition, there is a disadvantage that it is difficult to remove aromatic sulfur compounds and aromatic nitrogen compounds such as benzothiophene (BT), dibenzothiophene (DBT), especially when the aromatic nitrogen compound is included in the sample, the desulfurization catalyst is more easily Because of the poisoning, the desulfurization efficiency drops drastically. In particular, environmental regulations have been sharply strengthened since the 1990s, and recently, overseas advanced countries are expected to regulate the sulfur content of diesel to less than 10 ppm within the next four to five years. As a result, there is an urgent need for technology to greatly increase the stability and efficiency of existing catalysts or to replace them with more efficient methods than hydrogenated desulfurization and denitrification in order to remove as much nitrogen and sulfur compounds in the fuel as possible. It's happening.

 Ionic liquids, which are recently attracting attention as eco-friendly clean media, are a kind of molten salts, which vary depending on their composition, but generally have a very wide liquid temperature range (-100 to 300 ° C), and high solubility and ratio for organic and inorganic materials. It has characteristics such as ductility, non-volatile and high ionic conductivity, and it is possible to produce a wide variety of ionic liquids with desired properties by proper combination of cations and anions. The advantage is that it can be optimized. In particular, ionic liquids have high specific gravity and boiling point compared to organic solvents that are generally used, and thus, the separation of organic compounds and ionic liquids by phase separation or simple distillation is very easy, and has attracted attention as a medium to replace existing organic solvents. In addition, it has high solubility in inorganic and organometallic compounds used as a catalyst, which not only facilitates the recovery and reuse of the catalyst when used in the catalyst reaction, but also improves the activity, selectivity and stability of the catalyst in most catalytic reactions. It has been reported to.

The unique physical properties of ionic liquids are also used for the purpose of removing sulfur and nitrogen compounds from hydrocarbon fractions. In US Patent Publication No. 2003/0085156, US Patent Publication No. 2004/0045874, and Korean Patent Publication No. 10-2006-0119532, petroleum-based hydrocarbons are utilized by utilizing ionic liquids that do not mix with the hydrocarbon layer. A process for removing sulfur compounds from oils is described and described in WO 01/40150, WO 2008/034880, Paper Chem., 2008, 10, 524-531; Ind. Eng. Chem. Res. 2008, 47, 8801-8807 describe a method for extracting nitrogen compounds from hydrocarbon fractions using ionic liquids. Ionic liquids been used is already mostly an alkyl group is introduced imidazolium, pyridinium, pyrazolium, pyrrolidinium cations and SbF _6, such as pyridinium ^- (antimonate hexafluoro-carbonate), PF ₆ ^- Force page as (hexafluoro Sites ), BF ₄ ^{- (tetrafluoroborate), F -, Cl -,} Br -, I -, TFSI - ( bis methyl sulfonyl imide trifluoromethyl), alkyl sulfate, alkyl phosphate, alkyl phosphate, a halogenated metal-based Anion (AlCl ₃ , FeCl ₃ , CuCl series) It consists of anions, such as these. However, these ionic liquids have a problem in that they are not mixed with hydrocarbon oil but have low efficiency of removing nitrogen compounds.

Therefore, the present inventors have studied diligently to solve the above problems, and as a result, using a imidazolium-based ionic liquid containing zinc, nitrogen compounds, especially aromatic nitrogen compounds that are difficult to remove by conventional processes through a simple extraction process It has been found that the removal can be done very efficiently and the present invention has been completed.

It is therefore an object of the present invention to provide a method for the easy and economical removal of nitrogen compounds, especially aromatic nitrogen compounds, from hydrocarbon fractions using an imidazolium-based ionic liquid containing zinc.

The present invention relates to a method for removing nitrogen compounds contained in hydrocarbon fractions by using an imidazolium-based ionic liquid containing zinc produced by mixing imidazolium alkylsulfate represented by Formula 1 with ZnX ₂ .

[Formula 1]

Where

X is Cl, Br or I, preferably Cl,

R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group of C ₁ -C ₁₀ ,

R ₃ is an alkyl group of C ₁ -C ₄ .

The imidazolium-based ionic liquid formed by mixing the imidazolium alkyl sulfate represented by Chemical Formula 1 with ZnX ₂ includes a compound represented by the following Chemical Formula 2, and the compound is crucial for removing nitrogen compounds. It seems to play a role.

[Formula 2]

Where

R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group of C ₁ -C ₁₀ ,

m and n are each 1 or 2, m + n is 3,

X is Cl, Br or I, preferably Cl,

Y is R ₃ SO ₄ ,

R ₃ is an alkyl group of C ₁ -C ₄ .

In the present specification, an alkyl group of C ₁ -C ₁₀ means a straight or branched hydrocarbon having 1 to 10 carbon atoms, and includes, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and the like. It doesn't happen.

An alkyl group of C ₁ -C ₄ refers to a straight or branched hydrocarbon having 1 to 4 carbon atoms, and examples include, but are not limited to, methyl, ethyl, propyl, butyl, and the like.

The imidazolium alkyl sulfate represented by Chemical Formula 1 and ZnX ₂ are preferably mixed in a molar ratio of 1: 1 to 20: 1. If the molar ratio is less than 1: 1, the fluidity of the ionic liquid is inferior, and if it is more than 20: 1, the removal rate of the nitrogen compound is low.

In addition, it is preferable to mix the imidazolium alkyl sulfate represented by the formula (1) and ZnX ₂ at 50 to 70 ° C, and most preferably at 60 ° C.

The hydrocarbon fraction includes, but is not limited to, an oil fraction separated from petroleum such as liquefied petroleum gas, gasoline, jet fuel, kerosene, gas oil, heavy oil, and mixtures thereof.

The hydrocarbon fraction includes various kinds of nitrogen compounds, and the present invention is used to remove all kinds of nitrogen compounds, especially aromatic nitrogen compounds, included in hydrocarbon fractions, including indole, quinoline, acridine, and carbazole. Can be.

Hereinafter, a method of removing the nitrogen compound contained in the hydrocarbon fraction using the imidazolium-based ionic liquid containing zinc according to the present invention will be described in more detail. Removal method of the nitrogen compound of the present invention

(i) contacting an imidazolium-based ionic liquid containing zinc according to the invention with a hydrocarbon fraction comprising a nitrogen compound, extracting the nitrogen compound from the hydrocarbon fraction into the ionic liquid; And

(ii) separating the ionic liquid from the hydrocarbon fraction.

The weight ratio of the hydrocarbon fraction to the ionic liquid in the step (i) is preferably 1 to 50, more preferably 5 to 20. The extraction temperature is preferably from room temperature to 100 ℃, most preferably at room temperature. In addition, the extraction pressure is preferably atmospheric pressure to 50 atm, most preferably atmospheric pressure.

Separation in step (ii) can be carried out very easily by simple layer separation using the property that the ionic liquid and the hydrocarbon oil are not mixed.

The ionic liquid separated in step (ii) can be reused after removing the nitrogen compound. Removing the nitrogen compound from the ionic liquid may include heating the ionic liquid to evaporate the nitrogen compound or distilling the nitrogen compound from the ionic liquid into diethyl ether, quaternary-butyl methyl ether, dibutyl ether, benzene, n-heptane. Extraction with other solvents such as, stripping with hydrogen gas, stripping with inert gas, evaporating under reduced pressure, oxidizing nitrogen compounds to release in the form of nitrogen dioxide, or hydrogenating nitrogen compounds to form ammonia Release, supercritical extraction with carbon dioxide, or a combination of these methods. Most preferred among these methods is extraction with diethyl ether.

The method for removing the nitrogen compound according to the present invention may be carried out batchwise or continuously, preferably carried out continuously.

The imidazolium-based ionic liquid containing zinc according to the present invention can remove nitrogen compounds, especially aromatic nitrogen compounds, contained in hydrocarbon fractions very efficiently through a simple extraction process.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, it is obvious to those skilled in the art that the scope of the present invention is not limited to these examples.

Example 1 Preparation of an Imidazolium-Based Ionic Liquid Containing Zinc

The desired imidazolium alkylsulfate was synthesized according to the method described in JD Holbrey, WM Reichert, RP Swatloski, GA Broker, WR Pitner, KR Seddon, RD Rogers, Green Chem., 2002, 4 , 407413.

Then, imidazolium alkyl sulfate synthesized in a round bottom flask and ZnX ₂ (X = Cl, Br or I) are put together in a desired molar ratio and stirred at 60 ° C. for 1 hour to contain zinc-containing imidazolium ions. A sex liquid was prepared.

FT- of 1-ethyl-3-methylimidazolium ethyl sulfate zinc chloride ionic liquid prepared by mixing 1-ethyl-3-methylimidazolium ethyl sulfate and zinc chloride in a molar ratio of 2: 1 according to the above method The IR spectrum is shown in FIG. 1 in comparison with the FT-IR spectrum of 1-ethyl-3-methylimidazolium ethylsulfate and zinc chloride.

In addition, 1-ethyl-3 prepared by mixing 1-ethyl-3-methylimidazolium ethyl sulfate and zinc chloride in a molar ratio of 1: 1, 1.5: 1, 2: 1 and 5: 1, respectively, according to the above method. The FAB-MS spectrum of the zinc imidazolium ethyl sulfate zinc chloride ionic liquid is shown in FIG. 2.

1 and 2, when 1-ethyl-3-methylimidazolium ethyl sulfate and zinc chloride are mixed, ethyl sulfate and zinc chloride react to form ions having a new structure represented by Chemical Formula 2 regardless of the molar ratio. It was confirmed that a sex compound was produced.

Example 2: Removal of Nitrogen Compounds Using Imidazolium-Based Ionic Liquids Containing Zinc

Standard oil (n) containing nitrogen compounds (5000 ppm carbazole, 5000 ppm indole, 5000 ppm quinoline and 5000 ppm acridine) and 20000 ppm n-octane as internal standard 20 weight% of imidazolium-based ionic liquid containing zinc prepared according to Example 1 was added to 100% by weight of -heptane), and the mixture was stirred at room temperature for about 15 minutes, and allowed to stand for at least 15 minutes to completely separate the layers. The oil layer of the upper layer was recovered and the amount of nitrogen compound remaining therein was analyzed by GC and GC-MS, and the results are shown in Table 1 below in comparison with the imidazolium-based ionic liquid containing no zinc.

TABLE 1

Example Ionic liquid Nitrogen compounds Denitrification degree (%) 2 1-ethyl-3-methylimidazolium ethyl sulfate Carbazole 99.2 Indole 99.1 Quinoline 40.4 Acridine 39.4 1-ethyl-3-methylimidazolium ethyl sulfate
Zinc chloride Carbazole 100 Indole 100 Quinoline 86.2 Acridine 83.9

Example 3-8 Denitrification Investigation According to Kinds of Imidazolium-Based Ionic Liquid Containing Zinc

The denitrification degree of quinoline was analyzed in the same manner as in Example 2 while changing the type of imidazolium-based ionic liquid containing 5000 ppm of quinoline and containing zinc as shown in Table 2 below. Table 2 shows.

TABLE 2

Example Ionic liquid ^a Denitrification degree (%) 3 1-H-3-ethylimidazolium ethyl sulfate zinc chloride 86.5 4  1-ethyl-3-methylimidazolium ethylsulfate zinc chloride 89.2 5 1-butyl-3-ethylimidazolium ethyl sulfate zinc chloride 91.2 6 1-ethyl-3-methylimidazolium methylsulfate zinc chloride 88.4 7 1-Butyl-3-methylimidazolium methyl sulfate zinc chloride 89.8 8 1-octyl-3-methylimidazolium methylsulfate zinc chloride 93.9

^a molar ratio of ionic liquid to metal salt (ionic liquid / metal salt) = 2

Example 9-17 1-ethyl-3-methylimidazolium ethylsulfate and ZnCl ₂ Denitrification with Various Molar Ratios of

Denitration of quinoline was analyzed in the same manner as in Example 2 using 5000 ppm of quinoline as the nitrogen compound and changing the molar ratio of 1-ethyl-3-methylimidazolium ethyl sulfate and ZnCl ₂ as shown in Table 3 below. And the results are shown in Table 3 below.

[Table 3]

Example Molar ratio of 1-ethyl-3-methylimidazolium ethylsulfate / ZnCl ₂ Denitrification degree (%) 9 1-ethyl-3-methylimidazolium ethylsulfate alone 40.6 10 20: 1 81.6 11 10: 1 84.6 12 5: 1 85.3 13 4: 1 86.8 14 3: 1 88.8 15 2: 1 89.2 16 1: 1 90.2 17 ZnCl ₂ alone 52.3

Example 18 Reuse of Zinc-Containing Imidazolium-Based Ionic Liquids

The denitrification of quinoline was analyzed in the same manner as in Example 2 using 5000 ppm of quinoline as a nitrogen compound, and after separating the standard oil layer, 3 g of diethyl ether was added to 1 g of the remaining ionic liquid layer, and the mixture was cooled to about room temperature. After stirring for 5 minutes, the mixture was allowed to stand for 5 minutes to completely separate the layers. Then, the diethyl ether layer was separated, and the quinoline removal experiment was repeated in the same manner as in Example 2 using the remaining ionic liquid layer, and the results are shown in Table 4.

[Table 4]

Example Reuse count Denitrification degree (%) 18 One 89.0 2 87.3 3 86.7 4 86.2 5 82.9 6 82.0 7 81.4 8 80.5

Comparative Example 1-11: Denitrification Study Using Various Ionic Liquids

Denitrification of the nitrogen compound was analyzed in the same manner as in Example 2 using 5000 ppm quinoline as the nitrogen compound and the ionic liquid shown in Table 5 below, and the results are shown in Table 5 below.

TABLE 5

Comparative example Ionic liquid Denitrification degree (%) One 1-H-3-ethylimidazolium ethyl sulfate 33.1 2 1-ethyl-3-methylimidazolium ethyl sulfate 40.6 3 1-butyl-3-ethylimidazolium ethyl sulfate 52.7 4 1-ethyl-3-methylimidazolium methyl sulfate 55.3 5 1-butyl-3-methylimidazolium butyl sulfate 55.3 6 1-octyl-3-methylimidazolium methyl sulfate 53.3 7 1-ethyl-3-methylimidazolium diethylphosphate zinc chloride ^a 54.0 8 1-butyl-3-methylimidazolium dibutylphosphate zinc chloride ^a 52.7 9 1-ethyl-3-methylimidazolium ethylphosphite zinc chloride ^a 40.7 10 1-Butyl-3-methylimidazolium butyl phosphite zinc chloride ^a 45.7 11 1-ethyl-3-methylimidazolium bromide zinc chloride ^b 49.3

^a molar ratio of ionic liquid to metal salt (ionic liquid / metal salt) = 2

^b 20% by weight of 1-butyl-3-ethylimidazolium ethyl sulfate

1 shows (a) 1-ethyl-3-methylimidazolium ethyl sulfate, (b) 1-ethyl-3-methylimidazolium ethyl sulfate zinc chloride (1-ethyl-3-methylimidazolium ethyl sulfate Molar ratio of zinc chloride = 2: 1), and (c) FT-IR spectra of zinc chloride.

FIG. 2 is a FAB-MS spectrum of 1-ethyl-3-methylimidazolium ethyl sulfate zinc chloride (A: EtSO ₄ ⁻ ), and the molar ratio of 1-ethyl-3-methylimidazolium ethyl sulfate to zinc chloride ( FAB-MS spectra for a) 1: 1, (b) 1.5: 1, (c) 2: 1 and (d) 5: 1.

Claims (13)

Aromatic nitrogen contained in the hydrocarbon fraction using an imidazolium-based ionic liquid containing zinc, which is produced by mixing ZnX ₂ with an imidazolium alkyl sulfate represented by the following Chemical Formula 1 To remove a compound: [Formula 1]

[Formula 2]

Where X is Cl, Br or I, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group of C ₁ -C ₁₀ , R ₃ is an alkyl group of C ₁ -C ₄ , m and n are each 1 or 2, m + n is 3, Y is R ₃ SO ₄ . delete The method of claim 1, And X is Cl. The method of claim 1, The imidazolium alkyl sulfate represented by the formula (1) and ZnX ₂ characterized in that the mixture in a molar ratio of 1: 1 to 20: 1. The method of claim 1, The imidazolium alkyl sulfate represented by the formula (1) and ZnX ₂ characterized in that the mixture at 50 to 70 ℃. The method of claim 1 wherein the hydrocarbon fraction is selected from the group consisting of liquefied petroleum gas, gasoline, jet fuel, kerosene, gas oil, fuel oil and mixtures thereof. delete (i) an imidazolium-based ionic liquid containing zinc containing a compound represented by the following formula (2), which is produced by mixing imidazolium alkyl sulfate and ZnX ₂ represented by the following formula (1), containing an aromatic nitrogen compound Contacting the hydrocarbon fraction to extract the aromatic nitrogen compound from the hydrocarbon fraction into the ionic liquid; And (ii) removing the aromatic nitrogen compound contained in the hydrocarbon fraction comprising the step of separating the ionic liquid and the hydrocarbon fraction: [Formula 1]

[Formula 2]

Where X is Cl, Br or I, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group of C ₁ -C ₁₀ , R ₃ is an alkyl group of C ₁ -C ₄ , m and n are each 1 or 2, m + n is 3, Y is R ₃ SO ₄ . 9. The process of claim 8, wherein the weight ratio of hydrocarbon fraction to ionic liquid in step (i) is between 5 and 20. 9. The method of claim 8, wherein the extraction temperature in step (i) is room temperature. 9. The method of claim 8, wherein the extraction pressure in step (i) is atmospheric pressure. The method of claim 8, wherein the ionic liquid separated in step (ii) is reused after removing the nitrogen compound. 13. The process of claim 12, wherein the nitrogen compound is removed by diethyl ether.

Images