DESC:FIELD
The present disclosure relates to a metal oxide based ionic liquid.
BACKGROUND
Ionic liquids are used as catalysts and/or as solvents for various reactions such as alkylation, polymerization, dimerization, oligomerization, acetylation, metatheses and co-polymerization reactions. Ionic liquids are environmentally friendly since they produce very low or negligible amounts vapors as compared to conventional catalysts and solvents. As the demand of ionic liquid is increasing, there is a requirement for the development of ionic liquids from cheap and readily available chemicals and reagents.
One such source of readily available material is spent metal oxides produced in various industrial processes. Utilization of these spent metal oxides is highly desired in the industry. Further, metal oxides are abundantly available in the nature, and are cheap.
Thus, there is felt a need to provide an ionic liquid prepared from metal oxides and a simple, economical, environment friendly process for the preparation thereof.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide metal oxide based ionic liquids.
Still another object of the present disclosure is to provide a process for preparing the metal oxide based ionic liquids.
Yet another object of the present disclosure is to provide a simple, economical and environment friendly process for preparing the metal oxide based ionic liquids.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
In one aspect, the present disclosure provides an ionic liquid represented by formula (I),
[(M1)p(M2)q(O)m(X)n].(fluid medium), …. Formula (I)
wherein, M1 is at least one metal selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
M2 is at least one metal selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
X is at least one selected from the group consisting of halides, nitrate, sulphate, hydroxyl, and carbonates,
p is a number in the range of 1 to 5,
q is a number in the range of 1 to 5,
m is a number in the range of 1 to 20,
n is a number in the range of 1 to 20, and
In accordance with the embodiments of the present disclosure, M1, and M2 can be the same or different with respect to each other.
The fluid medium is at least one selected from the group consisting of benzene, toluene, xylene, chlorobenzene, bromobenzene, substituted benzenes, xylene, and ethylene dichloride.
In second aspect, the present disclosure provides a process for preparing the ionic liquid. The process comprises the following steps.
At least one metal oxide and at least one fluid medium are mixed in a reaction vessel maintained under inert atmosphere and stirred to obtain a mixture. At least one metal salt is slowly added to the mixture to obtain a suspension. The suspension is heated and stirred to obtain a product mixture. During this step, at least a portion of the solids present in the suspension reacts and forms product that is soluble in the fluid medium. The product mixture is cooled to obtain the ionic liquid.
The molar ratio of the metal oxide to the metal salt is in the range of 1:2.5 to 1: 4.
The weight ratio of the metal oxide to the fluid medium is in the range of 1:10 to 1:50.
The metal oxide is at least one selected from the group consisting of aluminum oxide (alumina), cupric oxide, zinc oxide, and titanium oxide.
In accordance with one embodiment of the present disclosure, the metal oxide is alumina.
In accordance with second embodiment of the present disclosure, the metal oxide is spent alumina.
The metal salt is at least one selected from a group consisting of AlCl3, FeCl3, GaCl3, InCl3, TiCl4, SnCl4, BiCl3, and ZrCl4.
The step of heating is carried out at a temperature in the range of 40 ?C to 90 ?C for a time period in the range of 1 hour to 10 hours. Stirring is carried out at a speed in the range of 100 rpm to 1500 rpm.

DETAILED DESCRIPTION
Ionic liquids are useful as a catalyst and/or a solvent for various chemical reactions such as alkylation, polymerization, dimerization, oligomerization, acetylation, metatheses and co-polymerization. There is ample availability of spent metal oxides from industrial processes.
The present disclosure envisages a metal oxide based ionic liquid and a process for its preparation, particularly using industrially available spent/ regenerated metal oxides.
In one aspect, the present disclosure provides an ionic liquid, which is represented by formula (I)
[(M1)p(M2)q(O)m(X)n].(fluid medium), …… Formula (I)
wherein, M1 is at least one metal selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
M2 is at least one metal selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
X is at least one selected from the group consisting of halides, nitrate, sulphate, hydroxyl, and carbonates,
p is a number in the range of 1 to 5, q is a number in the range of 1 to 5, m is a number in the range of 1 to 20, and n is a number in the range of 1 to 20.
The fluid medium is at least one selected from the group consisting of benzene, toluene, xylene, chlorobenzene, bromobenzene, substituted benzenes, xylene, and ethylene dichloride.
M1, and M2 are same or different with respect to each other.

The metal of the metal salt can be same as that of the metal of the metal oxide or these metals can be different from each other.
In second aspect, the present disclosure provides a process for preparing the ionic liquid of the present disclosure. The process comprises the following steps.
At least one metal oxide and at least one fluid medium are mixed in a reaction vessel maintained under inert atmosphere and stirred to obtain a mixture. At least one metal salt is slowly added to the mixture to obtain a suspension. The suspension is heated and stirred to obtain a product mixture. During this step, at least a portion of the solids present in the suspension react and form a product that is soluble in the fluid medium. The product mixture is cooled to obtain the ionic liquid.
The molar ratio of the metal oxide to the metal salt is in the range of 1:2.5 to 1: 4.
The weight ratio of the metal oxide to the fluid medium is in the range of 1:10 to 1:50.
The metal oxide is at least one selected from the group consisting of oxides of s-block, p-block, and transition metals.
The metal oxide is at least one selected from the group consisting of aluminum oxide (alumina), cupric oxide, zinc oxide, and titanium oxide.
In accordance with one embodiment of the present disclosure, the metal oxide is alumina.
In accordance with second embodiment of the present disclosure, the metal oxide is spent alumina. It is observed that the ionic liquid produced from the spent alumina results in similar ionic liquid as that obtained using fresh alumina. The catalytic properties of these ionic liquids are similar to each other.
The ionic liquid of the present disclosure can be prepared using more than one metal oxide.
The metal salt is at least one selected from the group consisting of transition metal salts and p-block metal salts. The metal salt is at least one selected from the group consisting of AlCl3, FeCl3, GaCl3, InCl3, TiCl4, SnCl4, BiCl3, and ZrCl4.
In accordance with one embodiment of the present disclosure, the metal salt is AlCl3.
The ionic liquid of the present disclosure can be prepared using more than one metal salts.
In accordance with one embodiment of the present disclosure, the metal salt is a mixture of AlCl3 and FeCl3.
The step of heating is carried out at a temperature in the range of 40 ?C to 90 ?C for a time period in the range of 1 hour to 10 hours. Stirring is carried out at a speed in the range of 100 rpm to 1500 rpm.
The activity, acidity, and viscosity of the ionic liquids of the present disclosure depend on the metal oxide and the metal salt that are used for preparation of the ionic liquids.
The process as disclosed in the present disclosure is simple, economical and environment friendly. The metal oxide used in the process of the present disclosure is cheap and readily available. Use of spent metal oxide for preparation of the ionic liquid reduces the environmental burden.
The Ionic Liquids of the present disclosure are useful as catalysts. These ionic liquids are used as catalysts for Friedel Crafts reactions, Diels Alder reactions, Fries Rearrangement, and other acid catalyzed reactions.
In accordance with the embodiments of the present disclosure, the ionic liquid is recovered after completion of the reaction. The recovered ionic liquid can be recycled.
Further the ionic liquids of the present disclosure are useful as fluid medium, electrolytes in batteries and can also be used in metal coatings.
The present disclosure is further described in light of the following laboratory scale experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. These laboratory scale experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial/commercial scale.
Examples:
Example 1: Activation of alumina
10g Alumina was dried in an oven at 120 ?C for 5 hours, followed by its activation at 200 ?C for 2 hours. The hot alumina was cooled in a desiccator to obtain activated alumina and the activated alumina was placed in an airtight container till further use.
Example 2: Washing and activation of spent alumina
Spent alumina having 20% organic material was used for this experiment. The spent alumina was treated by the following process:
Spent alumina (25 g) was mixed with acetone (50 mL) and the resultant mixture was stirred for 30 minutes. Stirring was stopped and the mixture was allowed to settle. Organic layer was decanted to obtain a residue. This was completion of the first cycle.
The residue was again mixed with fresh acetone (50 mL) and the cycle was repeated to complete the second cycle. Similarly, third cycle and fourth cycle were carried out. The washed alumina was filtered, and dried in oven at 100 ?C for 1 hour. The dried alumina was activated at 200 ?C for 5 hours. The hot alumina was cooled in a desiccator to obtain activated alumina and the activated alumina was placed in an airtight container till further use.

Example 3: Preparation of ionic liquid
To a reaction vessel maintained under nitrogen atmosphere and equipped with an overhead stirrer, was added benzene (20 mL) and stirred at 200 rpm. Activated alumina powder (1g) obtained from Example 1 was added to the stirred benzene, followed by further stirring for 10 minutes to obtain a mixture. Anhydrous AlCl3 (3.9 g) was added slowly to the mixture over 5 minutes to obtain a suspension. The suspension was heated at 80 ?C and stirred at 800 rpm. The solids present in the suspension reacted and formed a product that was soluble in benzene. After 4 hours, all the solids had reacted and a clear dark brown colored solution (the product mixture) was obtained. The product mixture was cooled while stirring at 800 rpm. Stirring was stopped to obtain the ionic liquid in benzene as a fluid medium.
Example 4: Preparation of ionic liquid using washed and activated spent alumina obtained from Example 2
The process of Example 3 was repeated using activated alumina obtained from Example 2 in place of alumina to obtain the ionic liquid.

Example 5: Preparation of ionic liquid using spent alumina
The process of Example 3 was repeated using spent alumina directly in place of alumina to obtain the ionic liquid. The spent alumina was obtained from industrial process for the preparation of linear alkyl benzene (LAB) from benzene and a hydrocarbon feed. The spent alumina comprised 8 weight % of organic matter which included benzene, the hydrocarbon feed, and LAB.

Example 6: Alkylation
To a reaction vessel maintained under nitrogen atmosphere and equipped with an overhead stirrer, was added benzene (0.202 liter) and hydrocarbon stream (0.52g) containing 12% C10-C14 olefins and 88 % paraffins, and stirred to obtain a mixture. The mixture was heated at 38 ?C, followed by addition of the ionic liquid (7 g) obtained in Example-3 to obtain a reaction mixture. The reaction mixture was stirred for 5 minutes to obtain a product mixture. Stirring was stopped and the product mixture was allowed to settle to obtain a biphasic mixture. The upper hydrocarbon layer comprised of linear alkyl benzene (LAB). The conversion of olefins to LAB was found to be 98%.

Example 7: Preparation of ionic fluid comprising two Metal halides
To a reaction vessel maintained under nitrogen atmosphere and equipped with an overhead stirrer, was added benzene (20 mL) and stirred at 200 rpm. Activated alumina powder (1g) was added to the stirred benzene, followed by stirring for 10 minutes to obtain a mixture. The mixture was charged with anhydrous AlCl3 (3.9 g) over 5 minutes, and the resulting mixture was stirred for 5 minutes, followed by addition of Anhydrous FeCl3 (1.32 g) over 5 minutes to obtain a suspension. The suspension was heated at 80 ?C and stirred at 800 rpm. The solids present in the suspension reacted and formed a product that was soluble in benzene. After 4 hours, a clear dark brown colored solution (the product mixture) was obtained. The product mixture was cooled while stirring at 800 rpm. Stirring was stopped to obtain the ionic liquid in benzene as a fluid medium.

Example 8: Acylation
Benzene (19.5 g) and Acetyl Chloride (3.5 g) were charged into a glass reactor maintained under nitrogen atmosphere, and stirred to obtain a mixture. The mixture was heated to 60 °C, and the ionic liquid catalyst (0.21 g) prepared in Example 3 was added to obtain a reaction mixture. The reaction mixture was stirred for 2 hours to obtain a product mixture. The product mixture was cooled and washed with 25 ml distilled water. The conversion of acetyl chloride was found to be 95%.

Example 9: Trans-alkylation
Heavier alkyl benzene stream (11.7 ml, 10.0 gm) containing 8 % linear alkyl benzene and 92% heaviers such as dilakylbenzenes and oligomers, was added to a reactor maintained under nitrogen atmosphere. Benzene 6.9 ml (6.0 gm) was added to the reactor to obtain a mixture. The mixture was heated to 80 oC under stirring for 15 minutes, followed by addition of the ionic liquid (1.1 g) prepared in Example 3. The reaction mixture was stirred for 2 hours at 80 oC to obtain a product mixture. The product mixture was cooled and allowed to settle to obtain a biphasic mixture. The upper hydrocarbon layer comprised of the product, and the lower layer comprised of the ionic liquid. The upper layer was analyzed by gas chromatography. The conversion of heaviers was 58% with 48% selectivity towards the formation of LAB.
The lower layer containing ionic liquid was subjected to separation and recovery of the ionic liquid. The recovered ionic liquid was recycled.

Example 10: Oligomerization
The ionic liquid catalyst (15.2 g) prepared in Example 3 was charged into an autoclave maintained at a temperature of 20 oC under an overhead stirrer. Condensed cis-2-Butene (142 g) at -15 oC was transferred into the autoclave via nitrogen pressure using a mass flow controller. The autoclave was closed, and the reaction mixture was stirred for 5 minutes to complete the reaction. It was observed that the temperature of the product mixture rose to 86 oC due to exotherm of the oligomerization. Stirring was stopped and the reaction mass was allowed to cool to 30 oC. The vent valve of the autoclave was slowly opened to vent off the unreacted olefin.
A biphasic mixture was obtained from the autoclave. The upper hydrocarbon layer and bottom catalyst layers were separated. The volume of the upper hydrocarbon layer was 130 cm. The hydrocarbon layer was analyzed by GC. The conversion of Cis-2-butene to oligomer was found to be 94%.
The lower layer containing the ionic liquid was subjected to separation and recovery of the ionic liquid. The recovered ionic liquid was recycled.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
• ionic liquids prepared from at least one metal oxide and at least one metal salt;
• use of spent metal oxide for preparation of the ionic liquid;
• a simple, economical, and environment friendly process for preparation of the ionic liquid; and
• use of the ionic liquid for alkylation, Friedel Crafts reactions, Diels Alder reactions, Fries Rearrangement, and other acid catalyzed reactions.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions, and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM:
1. An ionic liquid represented by formula (I)
[(M1)p(M2)q(O)m(X)n].(fluid medium), …. Formula (I)
wherein, M1 is at least one metal selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
M2 is at least one metal selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
X is at least one selected from the group consisting of halides, nitrate, sulphate, hydroxyl, and carbonates,
p is a number in the range of 1 to 5,
q is a number in the range of 1 to 5,
m is a number in the range of 1 to 20,
n is a number in the range of 1 to 20, and
wherein, M1, and M2 are same or different with respect to each other.
2. The ionic liquid as claimed in claim 1, wherein the fluid medium is at least one selected from the group consisting of benzene, toluene, xylene, chlorobenzene, bromobenzene, substituted benzenes, xylene, and ethylene dichloride.
3. A process for preparing the ionic liquid as claimed in claim 1, the process comprising the following steps:
a) mixing at least one metal oxide and at least one fluid medium in a reaction vessel maintained under inert atmosphere and stirring to obtain a mixture;
b) slowly adding at least one metal salt to the mixture to obtain a suspension, and
c) heating the suspension while stirring to obtain a product mixture, wherein at least a portion of the solids present in the suspension reacts and forms product that is soluble in the fluid medium; and
d) cooling the product mixture to obtain the ionic liquid.
4. The process as claimed in claim 3, wherein the molar ratio of the metal oxide to the metal salt is in the range of 1:2.5 to 1: 4.
5. The process as claimed in claim 3, wherein the weight ratio of the metal oxide to the fluid medium is in the range of 1:10 to 1:50.
6. The process as claimed in claim 3, wherein the metal oxide is at least one selected from a group consisting of aluminum oxide (alumina), cupric oxide, zinc oxide, and titanium oxide.
7. The process as claimed in claim 3, wherein the metal oxide is alumina.
8. The process as claimed in claim 7, wherein the alumina is spent alumina.
9. The process as claimed in claim 3, wherein the metal salt is at least one selected from the group consisting of AlCl3, FeCl3, GaCl3, InCl3, TiCl4, SnCl4, BiCl3, and ZrCl4.
10. The process as claimed in claim 3, wherein the step of heating is carried out at a temperature in the range of 40 ?C to 90 ?C for a time period in the range of 1 hour to 10 hours.
11. The process as claimed in claim 3, wherein stirring is carried out at a speed in the range of 100 rpm to 1500 rpm in step (c).