Claims:WE CLAIM:
1. A process for transalkylation for converting heavier alkyl aromatic compounds, present in a hydrocarbon feed containing benzene to linear alkyl aromatic compounds, said process comprising:
a. charging a first reactor, maintained at a temperature in the range of 50 °C to 140 °C, with said hydrocarbon feed;
b. introducing an inert gas into said first reactor;
c. adding at least one first fluid medium in said first reactor and stirring to form a first mixture;
d. catalyzing a cracking and addition reaction in the hydrocarbon feed with the help of an ionic liquid compound having the general formula M1•M2•M3•……..•Mn•(second fluid medium), added to said first mixture and by continuously stirring to form a second mixture comprising linear alkyl aromatic compounds;
e. optionally reducing the temperature of the said reactor to cool said second mixture to a temperature in the range of 15 °C to 30 °C;
f. allowing said second mixture to settle and separate into at least two layers, an upper layer comprising said first fluid medium and hydrocarbons including linear alkyl aromatic compounds, and a lower layer comprising said ionic liquid compound and said second fluid medium;
g. separating said upper layer comprising said first fluid medium and linear alkyl aromatic compounds from said lower layer to obtain a separated upper layer;
h. deacidifying acidic components in said separated upper layer in a second reactor using at least one deacidifying agent;
i. fractionally distilling said deacidified separated upper layer to obtain fractions of benzene, heavier alkyl benzene, lower hydrocarbons, and linear alkyl aromatic compounds; and
j. optionally recycling said fractions of benzene, and heavier alkyl benzene of step (i).
2. The process as claimed in claim 1, wherein said heavier alkyl aromatic compounds have carbon atoms ranging from 9 to 50 and said heavier alkyl aromatic compounds are selected from the group consisting of dialkyl benzenes, and oligomers.
3. The process as claimed in claim 1, wherein said first fluid medium is at least one selected from the group consisting of benzene, toluene, and ethyl benzene.
4. The process as claimed in claim 1, wherein said ionic liquid compound comprises at least one metal hydroxide, at least one metal halide, and at least one second fluid medium.
5. The process as claimed in claim 1 or claim 3, wherein said ionic liquid compound has a general formula M1•M2•M3•……..•Mn•(second fluid medium), wherein
‘M1’ is a metal hydroxide, wherein the metal of said metal hydroxide is at least one selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
‘M2’, ‘M3’……..‘Mn’ are metal halides independently selected from the group consisting of chloride, bromide, fluoride, iodide, and combinations thereof, wherein the metal of said metal halides is at least one selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
‘n’ is an integer ranging from 1 to 20; and
M1, M2, M3,…, Mn contain metals which may be the same or different.
6. The process as claimed in claim 1, wherein said second fluid medium is at least one selected from the group consisting of benzene, toluene, xylene, chlorobenzene, bromobenzene, substituted benzenes, and ethylene dichloride.
7. The process as claimed in claim 1, wherein said deacidifying agent is at least one selected from the group consisting of alumina, sodium hydroxide, and potassium hydroxide.
8. The process as claimed in claim 1, wherein the molar ratio of said first fluid medium to said heavier alkyl aromatic compound is in the range of 1:20 to 20:1.
9. The process as claimed in claim 1, wherein the volume ratio of said ionic liquid compound to said heavier alkyl aromatic compound is in the range of 0.01 to 3.
10. The process as claimed in claim 1, wherein the percentage conversion of said heavier alkyl aromatic compound to linear alkyl aromatic compound is in the range of 25 % to 99 %.
, Description:FIELD
The present disclosure relates to a process for the transalkylation for converting heavier alkyl aromatic compounds to linear alkyl aromatic compounds using ionic liquid.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
The term ‘Heavier alkyl aromatic compounds’ for the purpose of the present disclosure refers to hydrocarbons having carbon atoms ranging from 9 to 50.
The term ‘Transalkyaltion’ for the purpose of the present disclosure refers to a chemical reaction involving the transfer of an alkyl group from one organic compound to another.
The term ‘Linear alkyl aromatic compounds’ for the purpose of the present disclosure refers to the hydrocarbons comprising benzene substituted with linear alkyl groups.
The term ‘Clathrate’ for the purpose of the present disclosure refers to a chemical substance consisting of a lattice that traps or contains molecules.
The term ‘Eutectic’ for the purpose of the present disclosure refers to a system that describes a homogeneous solid mix of atomic and/or chemical species, to form a joint super-lattice, by striking a unique atomic percentage ratio between the components; as each pure component has its own distinct bulk lattice arrangement.
BACKGROUND
A transalkylation process is adapted to convert the heavier aromatic compounds to linear aromatic compounds. Conventionally, different catalysts are used for the transalkylation process for example, molecular sieve catalyst is used for the transalkylation process to convert benzene and diisopropylbenzene to cumene, group VIII metal on an aluminium support is used for transalkylating a polyalkylated aromatic compound, amine based catalyst for tranalkylation process and the like.
However, the transalkylation processes using different catalysts, described above, have certain drawbacks such as catalyst instability with feed stock and higher regeneration cost, higher operating condition, and expensive raw materials, thereby increasing the overall operating cost and which makes the transalkylation process uneconomical.
There is, therefore, felt a need to provide a simple, efficient, and economic transalkylation process.
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.
An object of the present disclosure is to provide a simple, efficient, and economic transalkylation process.
Another object of the present disclosure is to provide a catalyst system for transalkylation process.
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
The present disclosure relates to a process for the transalkylation for converting heavier alkyl aromatic compounds, present in a hydrocarbon feed containing benzene to linear alkyl aromatic compounds. The transalkylation process comprises a first reactor which is maintained at a temperature in the range of 50 °C to 140 °C is charged with the hydrocarbon feed. An inert gas is introduced into the first reactor. At least one first fluid medium is added in the first reactor and stirring to form a first mixture. A cracking and addition reaction in the hydrocarbon feed is catalysed with the help of an ionic liquid compound having the general formula M1•M2•M3•……..•Mn•(second fluid medium), added to the first mixture and by continuously stirring to form a second mixture comprising linear alkyl aromatic compounds. The temperature of the first reactor is optionally reduced to cool the second mixture to a temperature in the range of 15 °C to 30 °C. The second mixture is allowed to settle and separate into at least two layers, an upper layer comprising the first fluid medium and hydrocarbons including linear alkyl aromatic compounds, and a lower layer comprising the ionic liquid compound and the second fluid medium. The upper layer comprising the first fluid medium and the linear alkyl aromatic compounds is separated from the lower layer to obtain a separated upper layer. The acidic components in the separated upper layer are deacidified in a second reactor using at least one deacidifying agent. The deacidified separated upper layer is fractionally distilled to obtain fractions of benzene, heavier alkyl benzene, lower hydrocarbons, and linear alkyl aromatic compounds. The so obtained fractions of benzene, and heavier alkyl benzene is optionally recycled.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a system in accordance with the present disclosure for transalkylation of heavier alkyl aromatic compounds to linear alkyl aromatic compounds using an ionic liquid.
DETAILED DESCRIPTION
Different catalysts such as molecular sieve catalyst, group VIII metal on an aluminium support as catalyst, and amine based ionic liquid catalyst have been used in transalkylation processes. These catalysts have certain drawbacks like catalyst instability with feed stock, higher regeneration cost, higher operating condition, and expensive raw materials, which increases the overall operating cost and make the transalkylation process uneconomical.
The present disclosure envisages a process for the transalkylation for converting heavier alkyl aromatic compounds to linear alkyl aromatic compounds to mitigate the drawbacks mentioned herein above.
In accordance with the present disclosure, there is provided a process for transalkylation for converting heavier alkyl aromatic compounds, present in a hydrocarbon feed containing benzene, to linear alkyl aromatic compounds. The transalkylation process comprises the following steps.
In the first step, a first reactor, maintained at a temperature in the range of 50 °C to 140 °C, is charged with the hydrocarbon feed.
In accordance with an embodiment of the present disclosure, the hydrocarbon feed comprises 0 % to 50 % of the linear alkyl aromatic compounds, and 50 % to 100 % of the heavier alkyl aromatic compounds.
The heavier alkyl aromatic compound has carbon atoms ranging from 9 to 50 and the heavier alkyl aromatic compound is one selected from the group consisting of, but is not limited to, dialkyl benzenes, and oligomers.
In the second step, an inert gas is introduced into the first reactor.
In the third step, at least one first fluid medium is added in the first reactor and stirring to form a first mixture.
The first fluid medium can be at least one selected from the group consisting of, but is not limited to, benzene, toluene, and ethyl benzene.
The molar ratio of the first fluid medium to the heavier alkyl aromatic compound can be in the range of 1:20 to 20:1.
In the fourth step, a cracking and addition reaction in the hydrocarbon feed is catalysed with the help of an ionic liquid compound having the general formula M1•M2•M3•……..•Mn•(second fluid medium), added to the first mixture and by continuously stirring at a speed in the range of 400 rpm to 1000 rpm for a time period in the range of 15 minutes to 120 minutes to form a second mixture comprising linear alkyl aromatic compounds.
The ionic liquid is used as a catalyst to carry out the transalkylation process for converting the heavier alkyl aromatic compounds to linear alkyl aromaric compounds. The reaction takes place in two stages. In the first stage, ionic liquid breaks down (de-alkylates) the heavier alkyl aromatic compounds, and in the second stage, the alkyl group is added to the benzene (addition reaction) to form linear alkyl aromatic compounds.
The de-alkylation of the heavier alkyl aromatic compounds using ionic liquid is an exothermic reaction, whereas the alkylation of benzene is an endothermic reaction. Thus, the transalkylation process of the present application employs both exothermic and endothermic reactions. Therefore, net heat of the transalkylation process does not changes.
In accordance with an embodiment of the present disclosure, the ionic liquid compound comprises at least one metal hydroxide, at least one metal halide, and at least one second fluid medium.
The metal hydroxide can be at least one selected from the group consisting of, but is not limited to, Al(OH)3, Fe(OH)3, and Zn(OH)2. The metal hydroxide can be present in an amount ranging from 3 % to 40 % by weight of the ionic liquid compound.
The metal halide can be at least one selected from the group consisting of, but is not limited to, AlCl3, FeCl3, GaCl3, InCl3, TiCl4, SnCl4, BiCl3, and ZrCl4. The metal halide can be present in an amount ranging from 8 % to 90 % by weight of the ionic liquid compound.
The second fluid medium can be at least one selected from the group consisting of, but is not limited to, benzene, toluene, xylene, chlorobenzene, bromobenzene, substituted benzenes, and ethylene dichloride. The second fluid medium can be present in an amount ranging from 10 % to 70 % by weight of the ionic liquid compound.
The ionic liquid compound has a general formula M1•M2•M3•……..•Mn•(second fluid medium), wherein
‘M1’ is a metal hydroxide, wherein the metal of the metal hydroxide is at least one selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
‘M2’, ‘M3’……..‘Mn’ are metal halides independently selected from the group consisting of chloride, bromide, fluoride, iodide, and combinations thereof, wherein the metal of metal halides is at least one selected from the group consisting of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg;
‘n’ is an integer ranging from 1 to 20; and
M1, M2, M3,…, Mn contain metals which may be the same or different.

The dot (•) between M1, M2, M3, Mn, and (second fluid medium) represents at least one of co-ordinate covalent bond and weak van der waal forces, and therefore the product forms an ionic liquid/ eutectic mixture wherein the components are not ordinarily separable and take part in the reaction as a catalyst as a whole.
In an exemplary embodiment of the present disclosure, the ionic liquid compound is represented as Al(OH)3•3AlCl3•C6H6.
The viscosity of the ionic liquid composition ranges from 3 cP to 500 cP and density of the ionic liquid composition ranges from 1.00 g/cm3 to 2.50 g/cm3.
The molar ratio of metal hydroxide to metal halide can be in the range of 0.5:5 to 5:0.5.
The volume ratio of the ionic liquid compound to the heavier alkyl aromatic compound can be in the range of 0.01 to 3.
In the fifth step, which is optional, the temperature of the first reactor is reduced to cool the second mixture to a temperature in the range of 15 °C to 30 °C.
In the sixth step, the second mixture is allowed to settle and separate into at least two layers, an upper layer comprising the first fluid medium and hydrocarbons including linear alkyl aromatic compounds, and a lower layer comprising the ionic liquid compound and the second fluid medium.
In the seventh step, the upper layer comprising the first fluid medium and the linear alkyl aromatic compounds is separated from the lower layer to obtain separated upper layer.
In the eighth step, the acidic components in the separated upper layer are deacidified in a second reactor using at least one deacidifying agent.
The hydrocarbon feed of the present disclosure, if contains water, causes formation of acids. The acids that are formed are neutralized by using the deacidifying agent.
In accordance with an embodiment of the present disclosure, the deacidifying agent can be at least one selected from the group consisting of, but is not limited to, alumina, sodium hydroxide, and potassium hydroxide.
In the ninth step, the deacidified separated upper layer is fractionally distilled to obtain fractions of benzene, heavier alkyl benzene, lower hydrocarbons, and linear alkyl aromatic compounds. The distillation can be carried out using fractional distillation to obtain fractions of benzene, heavier alkyl benzene, lower hydrocarbons, and linear alkyl aromatic compounds.
In the tenth step, the fractions of benzene, and heavier alkyl benzene of step nine is recycled.
The conversion of the heavier alkyl aromatic compound to the linear alkyl aromatic compound can be in the range of 25 % to 99 %.
Furthermore, the use of transalkylation process, using the ionic liquid compound, of the present disclosure results in enhanced conversion of the heavier alkyl aromatic compound to the linear alkyl aromatic compound. Also, the raw materials used in the transalkylation process are easily available and economic. Therefore, the transalkylation process for the conversion of the heavier alkyl aromatic compound to the linear alkyl aromatic compound is simple, economic, and efficient.
The process for the preparation of the ionic liquid compound of the present disclosure is a single pot synthesis process.
The process of preparation of the ionic liquid compound comprises mixing at least one metal hydroxide and at least one second fluid medium at a temperature in the range of 10 °C to 35 °C to obtain a mixture. To this mixture at least one metal halide is added slowly under continuous stirring at a temperature in the range of 5 oC to 200 oC to obtain the ionic liquid compound. The ionic liquid compound of the present disclosure is in the form of ionic liquid clathrate.
The ionic liquid compound of the present disclosure is a metal hydroxide based clathrate. The clathrate is a chemical substance consisting of a lattice that traps or contains molecules of solvent in the metal hydroxide and metal halide.
In accordance with one embodiment of the present disclosure, a system, used for the transalkylation process that employs the ionic liquid compound of formula I, is disclosed. The system of the present disclosure comprises a plurality of mixers, a plurality of settlers, a purifier, a plurality of fractionating columns, and a catalytic regeneration unit, wherein each of the plurality of mixers, the plurality of settlers, the purifier and the plurality of fractionating columns are functionally coupled with each other.
The mixer can be at least one selected from the group consisting of stirred vessel, plug flow reactor, static mixer, jet mixer, pump mixer and combinations thereof. The settler unit can be selected from the group consisting of gravity settling vessel and decanter. The settler unit can be arranged horizontally or vertically comprising series of settlers arranged inside the settler unit either horizontally or vertically, or a combination thereof. The purifier can be selected from a group consisting of stirred vessel, centrifuge separator, column packed with alumina, evaporation and stripper, or any combination thereof.
More specifically, figure 1 illustrates a system for transalkylation of heavier alkyl aromatic compounds to linear alkyl aromatic compounds using an ionic liquid.
More specifically, in a non-limiting exemplary embodiment of the present disclosure, the system (100) comprises:
a first mixer (102a), a second mixer (102b), and a third mixer (102c);
a first settler (104a), a second settler (104b), and a third settler (104c);
a purifier (106);
a first fractionating column (108a), a second fractionating column (108b), and a third fractionating column (108c); and
a catalytic regeneration unit (110);
wherein the hydrocarbon feed is fed to the first mixer (102a) where an ionic liquid compound of formula I is added via line 3 to the first mixer (102a). The conversion of heavy aromatic compound to linear alkyl aromatic compound in the presence of the ionic liquid compound of formula I takes place in the first mixer (102a). The first mixer (102a) is in fluid communication with the second mixer (102b) where further conversion of heavy aromatic compound to linear alkyl aromatic compound in the presence of the ionic liquid compound of formula I takes place. The second mixer (102b) is in turn in fluid communication with the first settler (104a) where the linear alkyl aromatic compound and the ionic liquid compound of formula I layer are separated. The heavier catalyst layer which is denser than the linear alkyl aromatic compound, from first settler (104a) via line 4 is recycled to at least one of first mixer (102a) and the third mixer (102c) through catalyst recovery unit (110). The first settler (104a) is in turn in fluid communication with the third mixer (102c). The linear alkyl aromatic compound from the first settler (104a) is fed to the third mixer (102c) via line 5 where the ionic liquid compound of formula I is added via line 3. The third mixer (102c) is in turn in fluid communication with the second settler (104b) where the linear alkyl aromatic compound layer and the ionic liquid compound of formula I are separated. The heavier catalyst layer which is denser than the linear alkyl aromatic compound, from the second settler (104b) via line 6, is recycled to at least one of the first mixer (102a) and the third mixer (102c) through catalytic regeneration unit (110). The second settler (104b) is fluidly connected to the purifier (106), where the upper linear alkyl aromatic compound layer from second settler (104b) is fed to the purifier (106) via line 7, where the linear alkyl aromatic compound is washed with deacidifying agent via line 8. The deacidified linear alkyl aromatic compound from the purifier (106) is received by the third settler (104c) where further separation of linear alkyl aromatic compound occurs. The bottom layer of ionic liquid compound of formula I from the third settler (104c) is fed to catalytic regeneration unit (110) via line 9.
Further, the upper layer comprising the linear alkyl aromatic compound from the third settler (104c) is received by the first fractionating column (108a) via line 10 where the unsubstitued aromatic compound such as benzene is distilled off and recycled to line 1 via line 11. The residue of first fractionating column (108a) are received by the second fractionating column (108b) via line 12 to remove and recover lighter hydrocarbons via line 13. The residue of the second fractionating column (108b) are received by the third fractionating column (108c) via line 14 to separate linear alkyl aromatic compound such as linear alkyl benzene product by line 15, and the unreacted heavy alkyl aromatic compound by line 16 is recycled to the first mixer (102a) via line 2.
The present disclosure is further described in linear of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENT
Experiment 1: Process for the preparation of ionic liquid compound in accordance with the present disclosure
80.4 g of aluminium hydroxide and 500 g of benzene were introduced in a 2 Litre reactor and kept on a water bath at 25 °C to obtain a mixture. To this mixture, 412 g of aluminium chloride was slowly added with continuous stirring. Further, stirring was continued for 5 minutes. After stirring the reaction mixture for 5 min, the temperature of the water bath was increased to 80 °C. The reaction mixture was stirred vigorously at 800 rpm at 80 oC, until no solids appeared in the reactor. Once the reaction mixture was dark brown in color, with no solid deposition in it, heating was stopped and stirring was continued at 800 rpm. The reaction mixture was cooled to 25 oC to obtain the ionic liquid compound [Al(OH)3•3AlCl3•C6H6]. Further, the so formed ionic liquid compound was stored in an air tight container.
Experiment 2A: Process for transalkylation for converting heavier alkyl aromatic compound to linear alkyl aromatic compound in accordance with the present disclosure
In a 5 litre reactor, maintained at 80 °C, 1.75 litre of hydrocarbon stream, containing 5 % linear alkyl benzene and 95 % heavier alkyl benzene containing dialkyl benzenes and oligomers, was introduced. Nitrogen gas was introduced into the reactor. Further, 1.75 litre of benzene was added to the heavier alkyl benzene stream and stirred to form a first mixture. 700 g of the ionic liquid compound [Al(OH)3•3AlCl3•C6H6] prepared in experiment 1, was added and stirred at a speed of 500 rpm for 2 hours at 80 °C to obtain a second mixture. The so obtained second mixture was cooled at 25 °C and allowed to settle to obtain two layers containing an upper layer comprising benzene and hydrocarbons containing linear alkyl aromatic compounds, and a lower layer comprising the ionic iquid compound. The upper layer was separated by decantation and/or by separating funnel. The separated upper layer was deacidified and further analyzed by subjecting the deacidified upper layer to gas chromatography. The percent conversion of the heavier alkyl benzene to linear alkyl benzene was found to be 80 %.
Experiment 2B: Process for transalkylation of heavier alkyl benzene present in the upper layer in accordance with the present disclosure
The separated upper layer of experiment 2A was deacidified and distilled to obtain linear alkyl benzene (LAB), heavier alkyl benzene (HAB), benzene, and other components separately. Further, the obtained heavier alkyl benzene (HAB), and benzene were further subjected to transalkyation process which was similar to the transalkylation process of experiment 2A. The percent conversion of heavier alkyl benzene to linear alkyl benzene was found to be 49 %.
It is evident from experiment 2A and experiment 2B of the present disclosure that the reaction conditions for conversion of heavier alkyl benzene to linear alkyl benzene are milder and raw material used are easily available. It is also evident that the overall conversion of heavier alkyl benzene to linear alkyl benzene using both experiment 2A and experiment 2B is 90 %.
Furthermore, it is clearly seen from the above experiments that the use of the transalkylation process of the present disclosure using the ionic liquid compound results in enhanced conversion of heavier alkyl aromatic compound to linear alkyl aromatic compound. Therefore, the transalkylation process for conversion of heavier alkyl aromatic compound to linear alkyl aromatic compound is simple, economic, and efficient.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure, described herein above has several technical advantages including, but not limited to, the realization of a process for the tranalkylation for conversion of heavier alkyl aromatic compound to linear alkyl aromatic compound using ionic liquid compound wherein the process:
- is simple, economic, and efficient; and
- leads to improved conversion of heavier alkyl aromatic compound to linear alkyl aromatic compound.
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 disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments 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.