US20150027928A1

US20150027928A1 - Ionic liquids, methylcarbonate- or carboxylates-based, obtaining process and use thereof

Info

Publication number: US20150027928A1
Application number: US14/338,712
Authority: US
Inventors: Natalya Victorovna LIKHANOVA; Rodolfo Juventino Mora Vallejo; Georgina Cecilia Laredo Sanchez; Irina Victorovna LIJANOVA; Bernando RODRIGUEZ HEREDIA
Original assignee: Instituto Mexicano del Petroleo
Current assignee: Instituto Mexicano del Petroleo
Priority date: 2013-07-24
Filing date: 2014-07-23
Publication date: 2015-01-29
Also published as: CA2857778A1; CA2857778C; MX368989B; MX2013008554A

Abstract

Methylcarbonate-based ionic liquids (LIs) or carboxylates, derived from aliphatic or aromatic carboxylic acids are provided for the extraction of nitrogen compounds from hydrocarbon mixture (HCs) by liquid-liquid selective extraction, at room temperature and atmospheric pressure, where the LIs are immiscible with the HCs. This process is performed through an extraction by stifling two phases, followed by separation, or in a continuous flow system where the nitrogenous compounds are transferred to the phase formed by the LI and the total nitrogen content is substantially reduced in the HCS phase. The ionic liquids have the general formula C+A−, where:

- C+ is a heterocyclic organic cation, or quaternary ammonium-based; and
- A− is a methylcarbonate- or carboxylates-based anion, derived from aliphatic or aromatic carboxylic acids.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to new methylcarbonate- or carboxylates-based ionic liquids (LIs), derived from aromatic or aliphatic carboxylic acids, obtaining process and use thereof in the extraction of nitrogen organic or nitrogenous compounds: aliphatic and aromatic, pollutants as hydrocarbon mixtures (HCs), through a process of liquid-liquid selective extraction (LI-HCs), at room temperature and atmospheric pressure, where the LIs are immiscible with the HCs.
HCs mixtures to be denitrogenated using the present invention, preferably are oil-based fuels: gasoline, diesel, lightweight cyclical oil and turbosine; as well as other HCs streams obtained in the processes of oil refining.
The new LIs of the present invention, used in the denitrogenation of HCs mixtures, have the general formula C+A⁻, where C+ is a heterocyclic organic cation, preferably imidazolium, pyridinium or isoquinolinium-based, or quaternary ammonium-based; more preferably of two kinds: tetralkylammonium, and alkyl-pyridinium and alkyl imidazolium; where, A⁻ is a methylcarbonate- or carboxylates-based anion derived from aliphatic or aromatic carboxylic acids, preferably comprised by alkyl, cycloalkyl, benzyl, alkenyl, aromatic or alkyl functionalized chains, from 1 to 18 carbon atoms, such as: butanoate, hexanoate, octanoate and salicylate.

BACKGROUND OF THE INVENTION

The nitrogen or nitrogenous organic compounds have an inhibitory effect on the reactions of hydrodesulphurization (HDS), and poison the expensive catalysts comprised by noble metals for this process, which significantly hinder the obtaining of fuels with an ultra low sulfur content of ≧15 parts per million (ppm).
The production of fuels, according to the European Union environmental standards stipulated for the year 2005, require reducing the amount of sulfur in diesel and fuels to levels equal to or less than 10 ppm. For example, in Germany, reducing the amount of sulfur in fuel and diesel in 2005 up to 10 ppm was suggested. In case of the United States of America, the standard for the maximum sulfur content in fuel is limited to a maximum of 15 ppm since 2006.
In the case of Mexico, PEMEX Refinación (Oil Refining), on the basis of their commitment to produce and distribute fuel that comply with environmental laws under international standards of quality, Pemex is adjusting its parameters of gasoline and diesel production under the Mexican Standard NOM-086-Semarnat-Sener—SCFI-2005, which requires a maximum sulfur content in gasoline and diesel from 15 to 30 ppm for the years 2008 to 2010; in the case of the premium gasoline that is consumed all around the country, is on average of 30 ppm by weight, with a maximum of 80 ppm, a demand that is met with the production of Ultra Low Sulfur (UBA) gasoline.
In the case of Magna gasoline (fuel), the standard sets that since October 2008, gasoline consumed in the three major metropolitan areas of the country (Federal District, Monterrey and Guadalajara), must also comply with the same parameters for the sulfur content of that premium gasoline (30 ppm average/maximum 80 ppm), a situation that is complied, at least in one of the three metropolitan areas, but at a very high cost since a large portion of the premium fuel is imported.
For the rest of the country, the standard specifies that Magna gasoline (UBA is consumed since January 2009, a fact that has been postponed because of the delay in the post-treatment and modernization of PEMEX plant's biddings. This situation, of course, makes that Magna is still consumed in the rest of the country, which contains 350 ppm and that diesel contains 500 ppm instead of 30 ppm that the Mexican Standard NOM-086 stipulates, with their respective consequences in the emission of polluting compounds. It is urgent that our country begins to have UBA fuel and diesel available.
Therefore, for the production of a fuel with an ultra low sulfur diesel, HDS is necessary for a 99% of the sulfur compounds present in the hydrocarbon mixture (HCs), among which the benzothiophenes and alkyl-substituted dibenzothiophenes.
Several studies, among which, there is Laredo et al., “Nitrogen compounds characterization in atmospheric gas, oil and light cycle oil from a blend of Mexican crudes”. Fuel 81, 2002, pp. 1341-1350, have primarily shown that:

- The HDS catalytic reaction is significantly inhibited by organic nitrogenous compounds,
- There is a competitive adsorption between the nitrogen and sulfur containing compounds by the active sites of the catalytic converter, which causes nitrogen compounds to poison the HDS catalysts,
- The magnitude of inhibition depends on the type and concentration of the organic nitrogenous compounds, and
- In the direct streams of light fuel supply, the average content of total nitrogen is 100 to 300 ppm; while, in the most heavy streams, such as the light cyclical oil, the total nitrogen content is higher than 500 ppm.

Taking into account that the nitrogenous compounds are strong inhibitors in the HDS of sulfur compounds, great efforts have been made in the scientific world to develop pre-treatment processes for the selective extraction of nitrogenous compounds of the power currents of diesel and fuel. In these HCs, basic nitrogenous compounds are found: aniline, pyridine, acridine and quinoline, and derivatives thereof with alkyl substituents; and non-basic compounds: pyrrole, indol, carbazol and derivatives thereof.
Serban et al., in “Diesel desulfurization to make ULSD—overcoming nitrogen inhibition”, UOP LLC, a Honeywell Company, 2008, studied the effect of poisoning of catalysts in the HDS process of the nitrogenous compounds, demonstrating that even a few traces of 3-ethylcarbazole) could have a huge impact on the HDS of 4,6-diethyldibenzotiophene since the alkylcarbazoles are highly refractive and could be significantly adsorbed and block the active sites of the catalytic converter.
The use of physical adsorption methods for the selective extraction of nitrogen compounds is an attractive suggestion, due to the adsorption that can be carried out at room temperature and atmospheric pressure without the need for the use of hydrogen.
Among some of the technologies that have been developed to solve this problem is the use of solid adsorbents such as those used by SK Corporation in South Korea: “Method for manufacturing cleaner fuels”, U.S. Pat. No. 6,248,230 B1, issued on Jun. 19, 2001, where Min et al., provide a process for nitrogen extraction that is comprised by the use of various adsorbents, among which the following are referred: graphite, aluminas, ion exchange resins and activated charcoal.
Recently, the extraction of nitrogenous compounds through the use of LIs has been of great interest to the international scientific community. The LIs are known from more than 30 years ago, but its popularity in many different industrial applications started approximately in the past 10 years. They are applied as solvents and catalysts in alkylation reactions, polymerization and Diels-Alder, in addition to being used in electrochemical processes, but its use is more interesting as solvents for the extraction of different basic gases and impurities and heterocyclic HCs aromatic compounds, among others.
There is a diversity of work published on the subject of extraction of HCs sulfurous and nitrogenous compounds, such as:

“Ionic liquids on desulfurization of fuel oils”, Francisco et al., Fluid Phase Equilibria, 2010, 294, pp: 39-48, and
“Extraction Ability of Nitrogen-Containing compounds involved in the Desulfurization of Fuels by Using Ionic Liquids”. Alonso et al., Journal of Chemical & Engineering Data, 2010, Vol. 55, No. 9, pp: 3262-3267, which deal with the desulphurization and HCs denitrogenation using LIs containing fluoride in its structure.

Several jobs are devoted to said application using LIs that contain in its anion portion halogens and/or metal salts, for example:
In the US Patent Application 2010/0270211 A1, date of publication on Oct. 28, 2010, Ryszard A. Wolny incorporates the use of LIs and systems of metal ions for the extraction of nitrogenous compounds and sulfur containing HCs mixtures;
In the international patent application WO 2011/026972 A1, 113 published on Mar. 10, 2011, Gerrit Jan Harmsen et al., implemented the use of tetrachloroferrate-type LIs;
In the article “Selective extraction of neutral nitrogen compounds found in diesel feed by 1-butyl-3-methyl-imidazolium chloride”, Green Chemistry, 2008, 10, pp: 524-531, Xie et al., LIs with chloride are used as anion for the selective extraction of nitrogenous diesel compounds;
In the article “[bmim] AlCl14 Ionic Liquid for Deep Desulfurization of Real Fuels”, Energy & Fuels, 2008, 22, pp: 1774-1778, Roland Schmidt, reported the extraction of nitrogenous diesel compounds using LIs containing aluminum cations in its structure; and
In the article “Parallel Microwave-Assisted Synthesis of Ionic Liquids and Screening for Denitrogenation of Straight-Run Diesel Feed by Liquid-Liquid Extraction”, Combinatorial Chemistry & High Throughput Screening, 2012, Vol. 15, No. 5, pp: 427-432, Ceron et al., refer to the extraction of nitrogenous HCs compounds, using different LIs, imidazole and pyridine derivatives, where it is important to emphasize that, these LIs contain in its anion portion, halides and/or metal salts.
On the other hand, it is important to note that the LIs halides-free and metals lately attract scientific attention due to the fact that this class of LIs are more friendly to the environment, as Almeida et al., as illustrated in “Thermophysical Properties of Five Acetate-Based Ionic liquids”, Journal of Chemical & Engineering Data, 2012, 57, 3005-3013. In this regard, there are two large groups of LIs halides-free:

- 1) LIs protics, BrØnsted-type acids, and
- 2) LIs aprotics.

The synthesis of LIs protics, BrØnsted-type acids, it is very known and is comprised by a reaction of neutralization of acid with an organic basis, it is usually an amine, as reported in:

“An efficient protocol for the synthesis of 2-amino-4,6-diphenylpyridine-3-carbonitrile using ionic liquid ethylammonium nitrate”, Sarda et al., Mol Divers, 2009, 13, pp: 545-549; and
“Thermophysical properties of binary mixtures of {ionic liquid 2-hydroxy ethylammonium acetate+(water, methanol, or ethanol)}”, Alvarez et al., J. Chem. Thermodynamics, 2011, 43, pp: 997-1010).

The synthesis of LIs aprotics, halides-free, is performed in two stages of reaction, based on the method of alkylation (Step 1) by a methylsulfate or halogenoalcane or, as is reported in:

“Synthesis and Optical Properties of 1-Alkyl-3-Methylimidazolium Lauryl Sulfate Ionic liquids”, Obliosca et al., J. Fluoresc, 2007, 17, pp: 613-618;
and in the anion exchange (stage 2), as reported in:
“Amino-Functionalized Ionic liquid as A nucleophilic Scavenger in Solution Phase Combinatorial Synthesis”, Song et al., Journal of Combinatorial Chemistry, 2005, Vol. 7, No. 4, pp: 561-566.

Due to the method of alkylation (Step 1) by a halogenoalkane can cause difficulty in ion exchange in the Stage 2 providing the LIs low purity, the alkylation method more suitable for the synthesis of the LIs is with the use of dimethylcarbonate as agent of methylation, as reported in: *“Kinetic study of the Reaction of Dimethyl Carbonate with Trialkylamines”, Weisshaar et al., International Journal of Chemical Kinetics, 2010, 42, pp: 221-225, and “Synthesis and Characterization of Lauryl Trimethyl Ammonium Surfactants with New Counteranion Types”, Xu et al., Journal of Surfactants and Detergents, October 2009, 12, 4, pp. 351-354; according to the following synthesis diagram:
Synthesis Diagram of the Halides-Free LIs with the Use of Dimethylcarbonate.
Where:
N—R₁, R₂R₃=Tri-alkylamine or a heterocyclic cation or base quaternary ammonium.

(CH₃O)₂CO=Dimethylcarbonate

=Methylcarbonate of N-methyl-trialkylammonium
HA=Carboxylic acid or any acid with higher pK of carbonic acid
=Ionic liquid obtained with carboxylates-based anion
Japanese researchers Osamu Yagi and Shunpei Shimuzu in the article “Synthesis of Pure Treatmethylammonium Hydroxide Solution Free from Chloride ion by the electrolysis of Its Hydrogen carbonate”, Chemistry Letters, 1993, pp. 2041-2044, describes the use of dimethylcarbonate (DMC) as an agent of amines methylation. The method described in this article allows obtaining the LIs with methylcarbonate-type anion, derived from a very weak acid, which is very easy to exchange for any desirable anion derived from carboxylic acid with minor pKa of carbonic acid, with very weak conditions. The DMC exhibits a versatile chemical reactivity and tunable that depends on the experimental environments. Under reaction conditions at high temperatures the DMC primarily acts as an agent of methylation, while a reaction temperature equal to or less than 90° C. the DMC primarily acts as a methoxycarbonilating agent.
In these works:

“Extractive desulfurization and Denitrogenation of Fuels Using Ionic liquids”, Ind. Eng. Chem. Res., 2004, Vol. 43 No. 2, pp: 614-622; and
“Extractive Desulfurization of Fuel Oil Using Alkylimidazole and its mixture with Dialkylphosphate Ionic liquids”, Ind. Eng. Chem. Res., 2007, Vol. 46, No. 15, pp: 5108 series—5112,
Properties of the LIs to remove sulfur and nitrogen compounds were studied.

While, in the works:

“Deep oxidative desulfurization with task-specific ionic liquids: An experimental and computational study”, Gui et al., Journal of Molecular Catalysis A: Chemical, 2010, 331, pp: 64-70;
“Deep extraction of sulfur from real diesel by catalytic oxidation with compounds are manufactured under-free ionic liquid”, Liu et al., Korean J. Chem. Eng., 2012, Vol. 29, No. 1, pp: 49-53;
“Oxidation of dibenzothiophene catalyzed by Na2WO in a compounds are manufactured under-free ionic liquid”, Liu et al., Reac Kinet Mech Cat, 2011, 104, pp: 111-123;

It is the study of the desulphurization of diesel through a process of oxidation using LIs with the carboxylic acid group in the cation portion acid and sulfuric acid or phosphoric acid as the anion portion is studied.
In the US Patent Application 2005/0010076 A1, published on Jan. 13, 2005, Wasserscheid et al., make use of LIs to remove polar impurities and heteroatemic compounds of oil streams seeking protection of virtually all the cations and anions possible that a LI may form, but giving poor examples with the widely known LIs with anion-type aluminum chloride and methylsulfates, without giving an example of LI with acetate or benzoate type carboxylic anions, despite that they are all included in the patent application.
The works:

“Extraction of Thiophene or Pyridine from n-Heptane Using ionic liquids. Gasoline and diesel Desulfurization”, KedrA-Krolik et al., Industrial & Engineering Chemistry Research, 2011, 50, pp: 2296-2306; and
“Extraction of organic sulfur from hydrocarbon resources Using Ionic liquids”, Mochizuki and Sugawara, Energy & Fuels Vol. 22, No. 5, 2008, pp: 3303-3307; and the Patent Application:
US 2010/0051509 A1, Martinez Palou et al., published on Mar. 4, 2010, relate to the desulfuration from gasoline and diesel with halides-free LIs and metals, where the LIs have thiocyanate-type anions, methylsulfate and acetate.

However, several works on the halides—free type L is and metals the for application as catalysts in chemical reactions, among others:

“Synthesis of coumarins via Pechmann reaction catalyzed by 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable acidic ionic liquid”, Nader Khaligh Ghaffari, Catalysis Science & Technology, 2012, 2, pp: 1633-1636,
Camphor Ionic liquid: Correlation between Stereoselectivity and Cation-Anion Interaction”, Nobuoka et al., J. Org. Chem. 2005, Vol. 70, No. 24, pp: 10106-10108
“Ionic liquids promoted the C-acylation of Acetals in solvent-free conditions”, Martins et al., Catal Lett, 2009, 130, pp: 93-99.
“Synthesis of dimethyl carbonate catalyzed by-pyrrolidin carboxylic functionalized imidazolium salt via transesterification reaction”, Wang et al., Catalysis Science & Technology, 2012, 2, pp: 600-605;
“Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, compounds are manufactured under-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl fruit acids provide healing groups and deprotection of the obtained trimethylsilanes”, Shirini et al., Journal of Molecular Catalysis A: Chemical, 2012, 365, pp: 15-23;
“Natural Amino Acid-Based Ionic liquids as efficient catalysts for the synthesis of cyclic carbonates from CO2 and epoxides under Solvent-Free Conditions”, Wu et al., Letters in Organic Chemistry, 2010, Vol. 7, No. 1, pp: 73-78; and
“Symmetrical and unsymmetrical BrØnsted acidic ionic liquids for the effective conversion of particularly to 5-hydroxymethyl furfural”, D. A. Kotadia and S. S. Soni, Catalysis Science & Technology, 2013, 3, pp: 469-474.

LIs Derivatives of halides-free ortho borates have the potential to be applied in the processes of extraction of metal ions or as lubricants of steel/aluminum, as referred by:

“Halogen-free chelated orthoborate ionic liquids and organic ionic plastic crystals”, Shah et al., Journal of Materials Chemistry, 2012, 22, 6928-6938; and
“Novel halogen-free chelated orthoborate-phosphonium ionic liquids: synthesis and tribophysical properties”, Shah et al., Phys. Chem. Chem. Phys., 2011, 13, pp.: 12865-12873.

In addition, there are studies on the use of the Halogen-free LIs as additives for the azeotropes breaking in extractive distillation, as for example that of Shen et al., “Effect of the Ionic Liquid Triethylmethylammonium Dimethylphosphate on the Vapor Pressure of Water, Methanol, Ethanol, and Their Binary Mixtures”, Journal of Chemical & Engineering Data, 2011, 56, pp.: 1933-1940 or as an additive in the processes of protein purification by crystallization, as for example the of Hekmat et al., “Advanced protein crystallization using water-soluble ionic liquids as crystallization additives”, Opini Biotechnol Lett, 2007, 29, pp: 1703-1711.
None of the references mentioned suggests, much less claims for methylcarbonate- or carboxylates-based ionic liquids (LIs) (but not limited only to acetates and benzoates), the obtaining process and use thereof; in the extraction of nitrogen or nitrogenous organic compounds: aliphatic and aromatic, pollutants as hydrocarbon mixtures (HCs); through a process of selective extraction LI-HCs, at room temperature and atmospheric pressure, where the LIs are immiscible with the HCs.
It is therefore an object of the present invention to provide new methylcarbonate- or carboxylates based LIs, derived from aliphatic or aromatic carboxylic acids.
Another object of the present invention is to provide a process of new LIs synthesis having the general formula C⁺A⁻, where:
C⁺ is a heterocyclic organic cation or quaternary ammonium-based, and
A⁻ is a methylcarbonate- or carboxylates-based anion derived from aliphatic or aromatic carboxylic acids.
A further object of the present invention is to provide as the main use of the new LIs to remove nitrogen organic or nitrogenous compounds: aliphatic and aromatic, pollutants of HCs mixtures, where HCs mixtures to denitrogenate preferably are oil derived fuels: gasoline, diesel, oil and lightweight cyclical turbosine, as well as other HCs streams obtained in the processes of oil refining.

BRIEF DESCRIPTION OF THE DRAWINGS IN THE INVENTION

FIG. 1. In FIG. 1 Graphical results of the extraction of nitrogenous compounds from a primary light gas-type hydrocarbons (LPG) with N-methyl-triethylammonium butanoate (LI 2), using an ongoing flow system.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to new methylcarbonate- or carboxylates-based ionic liquids (LIs), derived from aliphatic or aromatic carboxylic acids, a process for obtaining and using in the extraction of nitrogen organic or nitrogenous compounds: aliphatic and aromatic, pollutants as hydrocarbon mixture (HCs); through a process of liquid-liquid selective extraction (LI-HCs), at room temperature and atmospheric pressure, where the LIs are immiscible with the HCs, due to the increased affinity for the organic nitrogenous compounds in the middle of LI with respect to the environment of HCs in which they are present. This process is performed through an extraction stirring the two phases, followed by a stage of separation, or in a continuous flow system, where the nitrogen compounds are transferred to the phase formed by the LI and as a result the total nitrogen content is substantially reduced in the HCS phase.
HCs mixtures to be denitrogenated using the present invention, preferably are oil-based fuels: gasoline, diesel, oil and lightweight cyclical turbosine; as well as other HCs streams obtained in the processes of oil refining.
The new LIs of the present invention have the general formula C⁺A⁻, where C⁺ is a heterocyclic organic cation or quaternary ammonium-based.
The heterocyclic organic cation preferably is imidazolium, pyridinium or isoquinolinium-based.
The heterocyclic organic cation-imidazolium based preferably is comprised by substituents of benzyl, or aromatic, cycloalkyl, alkenyl or aliphatic chains, from 1 to 10 carbon atoms, more preferably from 2 to 8 carbon atoms.
The heterocyclic organic cation of pyridinium based preferably is comprised by substituents of benzyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.
The isoquinolinium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.
The quaternary ammonium-based cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms.
The heterocyclic quaternary ammonium-based organic cation or more preferably is of two types: tetralkylammonium, and alkyl pyridinium and alkyl imidazolium.
A⁻ is a methylcarbonate- or carboxylates-based anion, preferably comprised by alkyl, cycloalkyl, benzyl, alkenyl, aromatic or alkyl functionalized chains, from 1 to 18 carbon atoms, such as: butanoate, hexanoate and octanoate.
The general structure of cations and anions, comprising the new LIs of the present invention, are shown in Table No. 1.

TABLE NO. 1

General Structure of cations and anions,
comprising the new Lis

C⁺ (Cations)

Imidazolium	Pyridinium	Ammonium

R, R¹, R²y R³are	R is a benzyl, cycloalkyl,	R, R¹, R²y R³are
benzyl, aromatic,	aromatic or aliphatic chain,	benzyl, aromatic,
cycloalkyl, alkenyl or	from 1 to 10 carbon atoms.	cycloalkyl, alkenyl
aliphatic chains, from 1		or aliphatic chains,
to 10 carbon atoms,		from 1 to 20 carbon
more preferably from 2		atoms, more
to 8 carbon atoms.		preferably from 1 to
		10 carbon atoms.

A⁻ (Anions)

Carboxylate	CH₃COOO− Methylcarbonate

R₄is a benzyl, cycloalkyl, aromatic or aliphatic
chain, from 1 to 18 carbon atoms

Process of the New LIs Synthesis

The new LIs of the present invention, were prepared according to the following scheme of two reaction synthesis steps:
Where:
N—R₃=Trialkylamine
And the groups R of N—R₃=benzyl chains, aromatic, cycloalkyl, alkenyl and/or aliphatic chains, from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms
(CH₃O)₂CO=dimethylcarbonate
⁺N—R₄/CH₃OCOO*=Methylcarbonate of N-methyl-trialkylammonium
R—COOH=carboxylic acid or any acid with higher pK of carbonic acid
⁺N—R₄/R—COO*=alkyl-, aryl-carboxylate of N-methyl-trialkylammonium
And the R group of R—COO=alkyl, cycloalkyl, benzyl, alkenyl, aromatic or alkyl functionalized, from 1 to 18 carbon atoms.
I. In the reaction stage I, a heterocyclic organic compound or quaternary ammonium-based (Example: N—R₃=Trialkylamine), with a methylcarbonate or carboxylates-based compound (Example (CH₃OR)₂COR=dimethylcarbonate), by stirring, for a period of 3 to 12 h, at a temperature of 110 to 180° C. and a pressure of 0 to 300 psi, for finally wash the LI formed with heptane and dry in the vacuum; and
II. In the reaction stage II, it is the ionic liquid (LI) formed in the reaction stage I (Example ⁺N—R₄/CH₃COO*═N-methyl-trialkylammonium methylcarbonate), with carboxylic acid (R—COOH) or any acid with higher pK of carbonic acid, by stirring for 15 to 30 min at room temperature, in order to obtain the corresponding ionic liquid (LI), which dries under vacuum for subsequent spectroscopic characterization;
Ionic liquids (LIs) obtained, methylcarbonate- or carboxylates-based, derived from aliphatic or aromatic carboxylic acids, have the general formula:
C⁺A⁻
Where:
C⁺ is a heterocyclic organic cation or quaternary ammonium-based, and
A⁻ is a methylcarbonate- or carboxylates-based anion.
With all the embodiments mentioned above.

Use of the New LIs in the HCs Denitrogenation

The use of the new LIs, methylcarbonate- or carboxylates-based, for the extraction of nitrogen organic or nitrogenous compounds: aliphatic and aromatic, pollutants of HCs mixtures, involves the following steps:
a) Mixing. Put the LI in contact, methylcarbonate- or carboxylates-based, with the mixture of HCs that contain impurities or pollutants as nitrogen organic or nitrogenous compounds, in a ratio between the mass of LI to HCs of 1:1,000,000 to 999:1, to start the interaction between the LI and the HCs;
b) Liquid-liquid selective extraction (LI-HCs). Shake the mixture obtained in step a), for 1 to 120 min., at room temperature and atmospheric pressure, so that the LI remove or extracts nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs, until the separation of the phase of the LI mixture of the HCS phase; and
c) Separation. The new phases of LI and HCs obtained in phase b), are separated physically between thereof. Now the new phase of LI contains nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs, the new HCS phase. contains a reduced amount or any amount detectable of said nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs.
Ratio between the mass of LI to HCs is preferably 1:100; the variation from this ratio depends on the identity and physical properties of the HCs to process and of the LI used, as well as their concentration, nature and solubility of nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs.
The time for liquid-liquid selective extraction (LI-HCs), preferably is from 1 to 30 min.
When the present invention is used in one or more stages of extraction or in a continuous flow system the nitrogenous compounds are transferred to the phase formed by the LI and as a result the total nitrogen content is substantially reduced in the phase of HC.

EXAMPLES

The following describes some practical examples to have a better understanding of the present invention, without limiting the scope thereof.

Synthesis of New LIs

Examples No. 1 to 4

Stage I: Synthesis of N-methyl-trialkylammonium methylcarbonate

In a batch reactor, 100 mmol of trialkylamine and 200 mmol of 30 dimethylcarbonate are mixed. The mixture is kept under stirring for a period of 5 to 10 h, at a temperature of 120 to 170° C. and a pressure of 30 to 250 psi. The reaction is complete and the product is obtained as a viscous liquid, semisolid or solid viscous yellow in color, which is flushed with heptane and dried under vacuum.

Stage II: Carboxylate Synthesis of N-methyl-trialkylammonium

In a glass reactor, supplied with stirring system, dissolve 10 mmol of N-methyl-trialkylammonium methylcarbonate, obtained in Stage I, 10 ml of methanol. After dispensing 10 mmol of the corresponding acid, the mixture is shaken for 20 min at room temperature, yielding a viscous amber liquid. The methanol is evaporated and the LI obtained is dried to empty.
The spectroscopic characterization is carried out through Nuclear Magnetic Resonance of 1H and 13C, using deuterated chloroform and deuterated dimethyl sulphoxide as solvents, the displacements are listed in parts per million (δ) with respect to the signal of the tetramethylsilane (TMS) as internal standard.
The spectroscopic characteristics of the new LIs synthesized, as well as yields obtained are shown below:

LI 1. N-methyl-triethylammonium methylcarbonate

The LI 1 was obtained in the form of solid yellow color, with a yield of 92%. IR (film): 2942, 1661, 1436, 1274, 1065, 862, 821 cm⁻¹. ¹H RMN (300 MHz, CDCl₃), δH (ppm): 1.38 (t, 9H, J=7.40 Hz), 3.23 (s, 3H), 3.47 (s, 3H), 3.56 (ct, 6H, J=7.44 Hz).
13C RMN (75 MHz, CDCl3), δC (ppm): 7.95 (3C), 46.90, 50.58, 55.60 (3C), 159.6 (COO).

LI 2. N-methyl-triethylammonium Butanoate

The LI 2 was obtained in the form of amber liquid, with a yield of 89%. IR (film): 2959, 2872, 1564, 1457, 1389, 1192, 1010, 784 cm⁻¹.
¹H RMN (300 MHz, CDCl₃), δH (ppm): 0.91 (t, 3H, J=7.42 Hz), 1.36 (t, 9H, J=7.14 Hz),
1.61 (sxt, 2H, J=7.29 Hz), 2.14 (t, 2H, J=7.56 Hz), 3.15 (s, 3H), 3.51 (ct, 6H, J=7.24 Hz).
¹³C RMN (75 MHz, CDCl3), δC (ppm): 7.91 (3C), 14.45, 20.12, 40.65, 46.88, 55.64 (3C), 179.00 (COO).

LI 3. N-methyl-triethylammonium hexanoate

The LI 3 was obtained in the form of viscous amber liquid, with a yield of 90%.
IR (film 2955, 2856, 1562, 1458, 1390, 1192, 1010 cm⁻¹.
¹H RMN (300 MHz, CDCl3), δH (ppm): 0.85 (t, 3H, J=3.43 Hz), 1.28-1.38 (m, 13H),

1.58 (m, 2H), 2.14 (t, 2H, J=7.64 Hz), 3.16 (s, 3H), 3.53 (ct, 6H, J=7.24 Hz).

¹³C RMN (75 MHz, CDCl3), δC (ppm): 7.91 (3C), 14.16, 22.69, 26.83, 32.27, 38.99,

46.86, 55.60 (3C), 179.34 (COO).

LI 4. N-methyl-triethylammonium octanoate

The LI 4 was obtained in the form of viscous amber liquid, with a yield of 91%.
IR (film): 2924, 2853, 1569, 1457, 1383, 1192, 1011, 811 cm⁻¹.
¹H RMN (300 MHz, CDCl3), 5H (ppm): 0.86 (t, 3H, J=3.43 Hz), 1.27-1.38 (m, 17H),

1.58 (m, 2H), 2.16 (t, 2H, J=7.8 Hz), 3.17 (s, 3H), 3.52 (ct, 6H, J=7.14 Hz).

¹³C RMN (75 MHz, CDCl3), δC (ppm): 7.92 (3C), 14.13, 22.57, 27.16, 29.37, 30.02,

31.92, 39.05, 46.83, 55.60 (3C), 179.48 (COO).

Use of New LIs

Example No. 5

Model Mixtures Denitrogenation (MM), in a Single Stage of Extraction with LI

These examples were made with a model mixture (MM) prepared by the dissolution of nitrogenous compounds such as quinoline, aniline, carbazol and indole in 739, 335, 586 and 1.797 ppm respectively, and the benzotiophene as the sulfur compound at a concentration of 42.000 ppm in a system of toluene/n-hexadecane (1:1) solvents, with a concentration of total nitrogen of 350 ppm.
The MM was treated with each of the new LIs obtained through examples Numbers 1 to 4:

LI 1. N-methyl-triethylammonium methylcarbonate

LI 2. N-methyl-triethylammonium butanoate

LI 3. N-methyl-triethylammonium hexanoate

LI 4. N-methyl-triethylammonium octanoate

Using a ratio of 1 to 20 of LI:MM, a single liquid-liquid selective extraction (LI-HCs), was carried out for 0.5 hours at room temperature and atmospheric pressure. After separation into two phases, the content of nitrogen compounds were determined by gas chromatography. The chemical structure of some of the LIs used are shown in Table No. 2, As well as the comparative results of the LIs used.

TABLE NO. 2

Extraction of nitrogen compounds in NM, in a single stage of extraction with LI,
using a ratio of 1:20 of LI:NINI.

Total nitrogen content 350 ppm, of the following type:

	Anilinic 50 ppm	Quinolinic 80 ppm	Indolic 70 ppm	Carbazolic 150 ppm	Total sulphur 10,000 ppm

Extraction Results (%)

LI 1	70.20	3.03	62.65	39.33	2.10
LI 2	92.20	11.50	100.00	74.00	4.70
LI 3	90.70	11.90	100.00	73.20	5.10
LI 4	88.50	7.54	92.63	91.05	5.30

The results of Table No. 2 show that the LIs with methylcarbonate anion based and carboxylates have halides-free and metals, lower the nitrogen content of the original model sample containing 350 ppm of total nitrogen, confirming that the use thereof is feasible in the extraction of organic nitrogenous compounds from HCs mixtures, such as: gasoline, diesel, cyclical light oil, turbosine and diesel, and other HCs streams obtained in the processes of oil refining.
Likewise, it is important to note that the sulfur content of the samples of HCs model reported in Table No. 2, after the extraction process with the LIs, virtually does not vary, which confirms the affinity of the LIs to the nitrogenous compounds.
Finally, in the Table No. 2, illustrates that the LIs 2 to 4 have higher selectivity for the nitrogenous compounds of indole, carbazol and aniline type, by removing practically 100% of indol from HCS.

Example No. 6

Denitrogenation of Model Mixtures (MM), in Various Stages of Extraction with LI

The process is the same as that of Example No. 5. However, the LI that had been used once for the denitrogenation MM was used again with a fresh portion of MM in a second, third, and optionally more stages of extraction, with a ratio of 1 to 40 of LI:MM. The results are shown in Table No. 3.

TABLE NO. 3

Extraction of nitrogen compounds in mm, in various
stages of extraction with LI 2, Using a ratio of 1:70 of LI:MM.

		Results of extraction
	Number of extractions	(%)

	1	67
	2	62
	3	56

The results of the Table No. 3 demonstrate the efficiency of the extraction process of the present invention and capacity of the LIs to remove the nitrogen compounds in various stages, without any purification of the LI used.
Table No. 3 shows that the LI 2 sets a constant extraction of nitrogen-containing compounds that at its peak is 67% and that is slowly diminishing as it is adding new load, at each stage of extraction efficiency rate drops to approximately 5%, which allows to consider the LIs halides-free and metals as good candidates to operate in extraction processes of continuous flow.

Example No. 7

Denitrogenation of LPG Type Hydrocarbon Mixture, in Extraction Systems for Continuous Flow with LI

This example was made with a primary light gas-type hydrocarbons (LPG), which presented a total concentration of nitrogen of 273 ppm. The test is carried out continuously in a glass column with a volume of 10 ml, packed with inert material (Pyrex glass) to a mesh size of 35/40 and that contains 6 g of LI 2. About 1 L of LPG were transferred with a nitrogen content of 273 ppm, at a flow rate of 0.17 ml/min at room temperature and atmospheric pressure. The percentage of total nitrogen extraction against the cumulative volume of the load in ml per each g of LI 2 shown in FIG. 1.
In FIG. 1 it is shown that the LI 2 shows a constant extraction of the nitrogenous compounds, its peak was 51% and was slowly diminishing as was adding new load. This material has a great capacity for extraction, reaching up to 20% of extraction of nitrogenous compounds after treating 130 ml/g of LI 2 on a system of extraction of continuous flow.

Claims

1. Methylcarbonate-based ionic liquids or carboxylates, derived from aliphatic or aromatic carboxylic acids, of general formula:

C+A−

Where:

C+ is a heterocyclic organic cation or quaternary ammonium-based, and

A− is a methylcarbonate- or carboxylates-based anion.

2. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, wherein the heterocyclic organic cation is preferably imidazolium, pyridinium or isoquinolinium-based.

3. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, wherein the imidazolium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, aromatic, cycloalkyl, alkenyl or aliphatic chains, from 1 to 10 carbon atoms, more preferably from 2 to 8 carbon atoms.

4. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, wherein the pyridinium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.

5. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, wherein the isoquinolin-based heterocyclic organic cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.

6. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, where the quaternary ammonium-based cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms.

7. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, wherein the quaternary ammonium-based heterocyclic organic cation or more preferably is of two types: tetralkylammonium, and alkyl pyridinium and alkyl imidazolium.

8. Methylcarbonate- or carboxylates-based ionic liquids, according to claim 1, wherein the carboxylates-based anion, preferably is comprised by substituents of alkyl, cycloalkyl, benzyl, alkenyl, alkyl or aromatic functionalized chains, from 1 to 18 carbon atoms, such as: butanoate, hexanoate, octanoate and salicylate.

9. A process for obtaining the Methylcarbonate- or carboxylates-based ionic liquids of claim 1, which comprises two stages of reaction:

I) In the reaction stage I, a heterocyclic organic compound or a quaternary ammonium-based compound is reacted with methylcarbonate- or carboxylates-based, by stifling, for a period of 3 to 12 h, at a temperature of 110 to 180° C. and a pressure of 0 to 300 psi, to finally wash the ionic liquid (LI) formed with heptane and dry them in the vacuum; and

II) In the reaction stage II, ionic liquid (LI) is treated which was formed in the reaction stage I, with carboxylic acid or any acid with higher pK of carbonic acid, by stifling for 15 to 30 min at room temperature, in order to obtain the corresponding ionic liquid (LI), which is dried to vacuum for the subsequent spectroscopic characterization;

Ionic liquids (LIs) obtained, methylcarbonate- or carboxylates-based, derived from aliphatic or aromatic carboxylic acids, have the general formula:

C+A−

Where:

C+ is a heterocyclic organic cation or quaternary ammonium-based, and

A− is a methylcarbonate- or carboxylates-based anion.

10. A process for obtaining Methylcarbonate- or carboxylates-based ionic liquids, according to claim 9, wherein the heterocyclic organic cation is preferably imidazolium, pyridinium or isoquinolinium-based.

11. The process for obtaining Methylcarbonate- or carboxylates-based ionic liquids, according to claim 9, wherein the imidazolium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, aromatic, cycloalkyl, alkenyl or aliphatic chains, from 1 to 10 carbon atoms, more preferably from 2 to 8 carbon atoms.

12. The process for obtaining Methylcarbonate- or carboxylates-based ionic liquids, according to claim 9, wherein the pyridinium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.

13. The process for obtaining Methylcarbonate- or carboxylates-based ionic liquids, according to claim 9, wherein the organic cation of heterocyclic isoquinolinium-based preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.

14. The process for obtaining Methylcarbonate- or carboxylates-based ionic liquids, according to claim 9, where the quaternary ammonium-based cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms.

15. The process for obtaining Methylcarbonate- or carboxylates-based ionic liquids, according to claim 9, where the carboxylates based-anion, preferably is comprised by substituents of alkyl, cycloalkyl, benzyl, alkenyl, alkyl or aromatic functionalized chains, from 1 to 18 carbon atoms, such as: butanoate, hexanoate, octanoate and salicylate.

16. The use of methylcarbonate-based ionic liquids or carboxylates, derived from aliphatic or aromatic carboxylic acids, of general formula:

C+A−

Where:

C+ is a heterocyclic organic cation or quaternary ammonium-based, and

A− is a methylcarbonate- or carboxylates-based anion,

In the extraction of nitrogen organic or nitrogenous compounds: aliphatic and aromatic, pollutants as hydrocarbon mixture (HCs), through the process of liquid-liquid selective extraction (LI-HCs), at room temperature and atmospheric pressure.

17. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, wherein the heterocyclic organic cation is preferably imidazolium, pyridinium or isoquinolinium-based.

18. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, wherein the imidazolium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, aromatic, cycloalkyl, alkenyl or aliphatic chains, from 1 to 10 carbon atoms, more preferably from 2 to 8 carbon atoms.

19. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, wherein the pyridinium-based heterocyclic organic cation preferably is comprised by substituents of benzyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.

20. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, wherein the isoquinolin-based heterocyclic organic cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 10 carbon atoms.

21. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, wherein the quaternary ammonium-based cation preferably is comprised by substituents of benzyl, alkenyl, cycloalkyl, aromatic or aliphatic chains, from 1 to 20 carbon atoms, more preferably from 1 to 10 carbon atoms.

22. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, wherein the organic cation heterocyclic quaternary ammonium-based or more preferably is of two types: tetralkylammonium, and alkyl pyridinium and alkyl imidazolium.

23. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, where the base anion carboxylates, preferably is comprised by substituents of chains alkyl, cycloalkyl, benzyl, alkenyl, alkyl or aromatic functionalized, from 1 to 18 carbon atoms, such as: butanoate, hexanoate, octanoate and salicylate.

24. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, where hydrocarbon mixture (HCs) to denitrogenate preferably are oil-based fuels.

25. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 24, wherein oil-based fuels to denitrogenate preferably are: gasoline, diesel, oil and lightweight cyclical turbosine, as well as other HCs streams obtained in the processes of oil refining.

26. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 16, where the process of liquid-liquid selective extraction (LI-HCs), at room temperature and atmospheric pressure involves the following steps:

a) Mixing. Put the LI in contact, methylcarbonate- or carboxylates-based, with the mixture of HCs that contain impurities or pollutants as nitrogen organic or nitrogenous compounds, in a ratio between the mass of LI to HCs of 1:1,000,000 to 999:1, to start the interaction between the LI and the HCs;

b) Liquid-liquid selective extraction (LI-HCs). Shake the mixture obtained in step a), for 1 to 120 min., at room temperature and atmospheric pressure, so that the LI remove or extracts nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs, until the separation of the phase of the LI mixture of the HCS phase; and

c) Separation. The new phases of LI and HCs obtained in phase b), are separated physically between thereof. Now the new phase of LI contains nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs, the new HCS phase. contains a reduced amount or any amount detectable of said nitrogen organic or nitrogenous compounds, pollutants or impurities of the HCs.

27. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 26, where the ratio between the mass of LI to HCs preferably is 1:100.

28. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 26, where the time of liquid-liquid selective extraction: LI-HCs, preferably is from 1 to 30 min.

29. The use of Methylcarbonate- or carboxylates-based ionic liquids, according to claim 26, where the process of liquid-liquid selective extraction (LI-HCs), is carried out in one or more stages of extraction and extraction systems in continuous flow.