DESC:FIELD
The present disclosure relates to a catalyst composition and a process for its preparation. Particularly, the present disclosure relates to a catalyst composition for oligomerization.
DEFINITION
As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which it is used indicates otherwise.
Oligomerization: The term “oligomerization” refers to a chemical process in which a small number (typically between 2 and 10) of monomer molecules join together to form an oligomer, a molecule consisting of a few repeating units.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Ethylene oligomerization to linear a-olefins (LAOs) is an increasingly important route to access valuable co-monomers, such as 1-hexene and 1-octene and the like. The co-monomers are in high demand and are used extensively in the production of linear low-density polyethylene (LLDPE) and polyolefin elastomer (POE) in which the 1-octene content is substantial (~40 wt%).
Ethylene oligomerization is classified as either a selective process or a non-selective process. When the process is non-selective, distribution of Linear Alpha Olefins (LAO) oligomers results oligomers in the range of C4 to C20+. The desired fragments are then separated by using fractional distillation to obtain different fractions. These different fractions can be used for different applications, depending on the market demands. As the market application distribution is constantly shifting, non-selective oligomerization often results in ‘unwanted’ LAO’s.
A solution to this problem is to develop selective oligomerization. Selective dimerization, trimerization and tetramerization of ethylene do exist with 1-butene, 1-hexene or 1-octene, each having its own applications. This selective behaviour is attributed completely to the underlying chemistry of the process. Of all the polymerization/oligomerization processes described thus far, the selective trimerization and the selective tetramerization are the most challenging. Conventionally known catalyst systems for selective trimerization and tetramerization are associated with certain drawbacks such as formation of 1-hexene as the major by-products along with the formation of significant amounts of methylcyclopentane and methylenecyclopentane which are undesired. Further, the processes for oligomerization by using the conventionally known catalyst systems are carried out at higher temperatures and hence, not feasible for commercial production.
There is, therefore, felt a need to develop a catalyst composition for oligomerization that mitigates the drawbacks mentioned herein above or at least provides a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
An object of the present disclosure is to ameliorate one or more problems of the background or to at least provide a useful alternative.
Another object of the present disclosure is to provide a catalyst composition for oligomerization.
Still another object of the present disclosure is to provide a catalyst composition that has high selectivity and productivity for 1-octene.
Yet another object of the present disclosure is to provide a catalyst composition that produces 1-octene with minimum undesirable side products.
Still another object of the present disclosure is to provide a simple and economic process for the preparation of a catalyst composition for oligomerization.
Yet another object of the present disclosure is to provide a simple and economic process of oligomerization by using a catalyst composition.
Still another object of the present disclosure is to provide a process of oligomerization by using a catalyst composition that is carried out at an ambient temperature.
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 an aspect, the present disclosure relates to a catalyst composition comprising:
a) a chromium precursor;
b) a first ligand;
c) a second ligand;
d) a co-catalyst; and
e) a fluid medium.
In an embodiment of the present disclosure, the catalyst composition comprises
i. the chromium precursor in an amount in the range of 2 to 10 mass% with respect to the total mass of the catalyst composition;
ii. the first ligand in an amount in the range of 10 to 20 mass% with respect to the total mass of the catalyst composition;
iii. the second ligand in an amount in the range of 1 to 5 mass% with respect to the total mass of the catalyst composition;
iv. the co-catalyst in an amount in the range of 2 to 6 mass% and with respect to the total mass of the catalyst composition; and
v. the fluid medium in an amount in the range of 65 to 75 mass%, with respect to the total mass of the catalyst composition.
In an embodiment of the present disclosure, the catalyst composition comprises:
a) the chromium precursor in an amount in the range of 6 mass% to 7 mass%;
b) the first ligand in an amount in the range of 15 mass% to 16 mass%;
c) the second ligand in an amount in the range of 3 mass% to 4 mass%;
d) the co-catalyst in an amount in the range of 4 mass% to 5 mass%; and
e) the fluid medium in an amount in the range of 70 mass% to 71 mass%,
wherein the mass% of each component is with respect to the total mass of the catalyst composition.
In an embodiment of the present disclosure, the chromium precursor is selected from the group consisting of CrCl3, chromium (acetylacetonate)3, chromium (NO3)3, and chromium (acetate)3.
In an embodiment of the present disclosure, the chromium precursor is chromium (acetylacetonate)3 [Cr(aca)3].
In an embodiment of the present disclosure, the first ligand is a phosphorus-nitrogen-phosphorus (PNP) ligand of Formula I

wherein X is selected from

In an embodiment of the present disclosure, X is isopropyl.
In an embodiment of the present disclosure, the first ligand is a PNP ligand of Formula Ia

In an embodiment of the present disclosure, the second ligand is at least one selected from the group consisting of triphenyl phosphine, diphenylphosphine, borane diphenylphosphine complex, chlorodiphenylphosphine, diphenyl phosphoryl chloride, tricyclohexylphosphine, 4-(diphenylphosphino)styrene, diphenylvinylphosphine, allyldiphenylphosphine, diphenyl-2-pyridylphosphine, and 4-(dimethylamino)phenyldiphenylphosphine.
In an embodiment of the present disclosure, the second ligand is triphenyl phosphine (PPh3).
In an embodiment of the present disclosure, the co-catalyst is selected from the group consisting of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and polymethylaluminoxane (PMAO).
In an embodiment of the present disclosure, the co-catalyst is methylaluminoxane (MAO).
In an embodiment of the present disclosure, the fluid medium is at least one selected from the group consisting of toluene, cyclohexane, hexane, and isopentane.
In an embodiment of the present disclosure, a molar ratio of the co-catalyst to the chromium precursor is in the range of 300:1 to 600:1.
In another aspect, the present disclosure relates to a process for the preparation of a catalyst composition. The process comprises preparing a solution of a second ligand in a first fluid medium and adding a first ligand to the solution to obtain a first mixture. Chromium precursor is separately mixed in a second fluid medium to obtain a chromium precursor solution. The first mixture is added to the chromium precursor solution under stirring to obtain a homogeneous mixture. A predetermined amount of a co-catalyst is separately mixed in a third fluid medium to obtain a co-catalyst solution. The co-catalyst solution is added to the homogeneous mixture under stirring to obtain the catalyst composition.
In an embodiment of the present disclosure, the first ligand is a PNP ligand of Formula I

wherein X is selected from

In an embodiment of the present disclosure, X is isopropyl.
In an embodiment of the present disclosure, the first ligand is a PNP ligand of Formula Ia

In an embodiment of the present disclosure, the second ligand is at least one selected from the group consisting of triphenyl phosphine, diphenylphosphine, borane diphenylphosphine complex, chlorodiphenylphosphine, diphenyl phosphoryl chloride, tricyclohexylphosphine, 4-(diphenylphosphino)styrene, diphenylvinylphosphine, allyldiphenylphosphine, diphenyl-2-pyridylphosphine and 4-(dimethylamino)phenyldiphenylphosphine.
In an embodiment of the present disclosure, the second ligand is triphenyl phosphine (PPh3).
In an embodiment of the present disclosure, the chromium precursor is selected from the group consisting of CrCl3, chromium (acetylacetonate)3, chromium (nitrate)3, and chromium (acetate)3.
In an embodiment of the present disclosure, the co-catalyst is selected from the group consisting of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and polymethylaluminoxane (PMAO).
In an embodiment of the present disclosure, the first fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane.
In an embodiment of the present disclosure, the second fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane.
In an embodiment of the present disclosure, the third fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane.
In an embodiment of the present disclosure, a predetermined amount of the first ligand is in the range of 10 mass% to 45 mass% with respect to the total mass of the homogeneous mixture.
In an embodiment of the present disclosure, a predetermined amount of the second ligand is in the range of 10 mass% to 20 mass% with respect to the total mass of the homogeneous mixture.
In an embodiment of the present disclosure, a predetermined amount of the chromium precursor is in the range of 10 mass% to 20 mass% with respect to the total mass of the homogeneous mixture.
In an embodiment of the present disclosure, the first mixture and the chromium precursor are mixed at a temperature in the range of 30 °C to 35 °C for a time period in the range of 2 minutes to 30 minutes.
In an embodiment of the present disclosure, the co-catalyst solution and the homogeneous mixture are mixed at a temperature in the range of 20 °C to 40 °C for time period is in the range of 2 minutes to 10 minutes.
In an embodiment of the present disclosure, the predetermined amount of the co-catalyst is in the range of 5 to 15 mass% with respect to the total mass of the co-catalyst solution.
In an embodiment of the present disclosure, a molar ratio of the co-catalyst to the chromium precursor is in the range of 300:1 to 600:1.
In an embodiment of the present disclosure, the process comprises the following steps:
i) preparing a solution of triphenyl phosphine (PPh3) by dissolving triphenyl phosphine in toluene and adding a PNP ligand of Formula Ia to the solution to obtain a first mixture;

ii) separately mixing predetermined amounts of chromium (acetylacetonate)3 and toluene to obtain a chromium precursor solution;
i) adding the first mixture to the chromium precursor solution under stirring at a temperature in the range of 30 °C to 35 °C for a time period in the range of 2 minutes to 30 minutes to obtain a homogeneous mixture;
ii) separately mixing predetermined amounts of methylaluminoxane (MAO) and toluene to obtain a co-catalyst solution; and
iii) adding the co-catalyst solution to the homogeneous mixture under stirring at a temperature in the range of 20 °C to 40 °C for a time period in the range of 2 minutes to 10 minutes to obtain the catalyst composition.
In still another aspect, the present disclosure relates to a process for oligomerization. The process comprises contacting at least one olefinic monomer with the catalyst composition, at a temperature in the range of 30 °C to 45 °C for a time period in the range of 30 minutes to 90 minutes to obtain 80% to 90% 1-octene.
In an embodiment of the present disclosure, the olefinic monomer is at least one selected from the group consisting of ethylene monomer, and 1-butene monomer.
In an embodiment of the present disclosure, the process comprises contacting ethylene with the catalyst composition, at a temperature in the range of 30 °C to 45 °C for a time period in the range of 30 minutes to 90 minutes to obtain 80 to 90% 1-octene.
DETAILED DESCRIPTION
The present disclosure relates to a catalyst composition for oligomerization. Particularly, the present disclosure relates to a catalyst composition for the preparation of 1-Octene.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Ethylene oligomerization to linear a-olefins (LAOs) is an increasingly important route to access valuable co-monomers, such as 1-hexene and 1-octene and the like. The co-monomers are in high demand and are used extensively in the production of linear low-density polyethylene (LLDPE) and polyolefin elastomer (POE) in which the 1-octene content is substantial (~40 wt%).
Ethylene oligomerization is classified as either a selective process or a non-selective process. When the process is non-selective, distribution of oligomers (LAO’s) results oligomers in the range of C4 to C20+. The desired fragments are then separated by using fractional distillation to obtain different fractions. These different fractions can be used for different applications, depending on the market demands. As the market application distribution is constantly shifting, non-selective oligomerization often results in ‘unwanted’ LAO’s.
A solution to this problem is to develop selective oligomerization. Selective dimerization, trimerization and tetramerization of ethylene do exist with 1-butene, 1-hexene or 1-octene, each having its own applications. This selective behaviour is attributed completely to the underlying chemistry of the process. Of all the polymerization/oligomerization processes described thus far, the selective trimerization and the selective tetramerization are the most challenging. Conventionally known catalyst systems for selective trimerization and tetramerization are associated with certain drawbacks such as formation of 1-hexene as the major by-products along with the formation of significant amounts of methylcyclopentane and methylenecyclopentane which are undesired. Further, the processes for oligomerization by using the conventionally known catalyst systems are carried out at higher temperatures and hence, not feasible for commercial production.
The present disclosure provides a catalyst composition for oligomerization, a process for the preparation of a catalyst composition and a process of oligomerization by using a catalyst composition. Particularly, the present disclosure envisages a catalyst composition for the preparation of 1-Octene.
In an aspect, the present disclosure provides a catalyst composition comprising:
a) a chromium precursor;
b) a first ligand;
c) a second ligand;
d) a co-catalyst; and
e) a fluid medium.
In an embodiment of the present disclosure, the catalyst composition comprises
a) the chromium precursor in an amount in the range of 2 to 10 mass% with respect to the total mass of the catalyst composition;
b) the first ligand in an amount in the range of 10 to 20 mass% with respect to the total mass of the catalyst composition;
c) the second ligand in an amount in the range of 1 to 5 mass% with respect to the total mass of the catalyst composition;
d) the co-catalyst in an amount in the range of 2 to 6 mass% and with respect to the total mass of the catalyst composition; and
e) the fluid medium in an amount in the range of 65 to 75 mass%, with respect to the total mass of the catalyst composition.
In an embodiment of the present disclosure, the catalyst composition comprises:
i. the chromium precursor in an amount in the range of 6 mass% to 7 mass%;
ii. the first ligand in an amount in the range of 15 mass% to 16 mass%;
iii. the second ligand in an amount in the range of 3 mass% to 4 mass%;
iv. the co-catalyst in an amount in the range of 4 mass% to 5 mass%; and
v. the fluid medium in an amount in the range of 70 mass% to 71 mass%,
wherein the mass% of each component is with respect to the total mass of the catalyst composition.
In an embodiment of the present disclosure, the chromium precursor is selected from the group consisting of CrCl3, chromium (acetylacetonate)3, chromium (nitrate)3, and chromium (acetate)3.
In an embodiment of the present disclosure, the chromium precursor is chromium (acetylacetonate)3 [Cr(aca)3].
In an embodiment of the present disclosure, the first ligand is a phosphorus-Nitrogen-Phosphorus (PNP) ligand of Formula I

wherein X is selected from

In an embodiment of the present disclosure, X is isopropyl.
In an embodiment of the present disclosure, the first ligand is a PNP ligand of Formula Ia

In an exemplary embodiment, the first ligand is a PNP ligand ((phenyl)2PN(isopropyl)P(phenyl)2 ligand) of Formula Ia.
In an embodiment of the present disclosure, the second ligand is at least one selected from the group consisting of triphenyl phosphine, diphenylphosphine, borane diphenylphosphine complex, chlorodiphenylphosphine, diphenyl phosphoryl chloride, tricyclohexylphosphine, 4-(diphenylphosphino)styrene, diphenylvinylphosphine, allyldiphenylphosphine, diphenyl-2-pyridylphosphine, and 4-(dimethylamino)phenyldiphenylphosphine.
In an embodiment of the present disclosure, the second ligand is triphenyl phosphine (PPh3).
In an embodiment of the present disclosure, the co-catalyst is selected from the group consisting of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and polymethylaluminoxane (PMAO).
In an exemplary embodiment, the co-catalyst is methylaluminoxane (MAO).
In an embodiment of the present disclosure, the fluid medium is at least one selected from the group consisting of toluene, cyclohexane, hexane, and isopentane. In an exemplary embodiment, the fluid medium is toluene.
In an embodiment of the present disclosure, a molar ratio of the co-catalyst to the chromium precursor is in the range of 300:1 to 600:1. In an exemplary embodiment, the molar ratio of the co-catalyst to the chromium precursor is 500:1. In another exemplary embodiment the molar ratio of the co-catalyst to the chromium precursor is 300:1.
In an exemplary embodiment, the catalyst composition comprises:
a) 6.16 mass% of chromium (acetylacetonate)3 with respect to the total mass of the catalyst composition;
b) 15.5 mass% of a PNP ligand of Formula Ia with respect to the total mass of the catalyst composition;

c) 3.05 mass% of triphenyl phosphine (PPh3) the with respect to the total mass of the catalyst composition;
d) 4.4 mass% of methylaluminoxane (MAO) with respect to the total mass of the catalyst composition; and
e) 70.89 mass% of toluene with respect to the total mass of the catalyst composition.
In another aspect, the present disclosure provides a process for the preparation of a catalyst composition. The process comprises preparing a solution of a second ligand in a first fluid medium and adding a first ligand to the solution to obtain a first mixture. A predetermined amount of a chromium precursor is separately mixed in a second fluid medium to obtain a chromium precursor solution. The first mixture is added to the chromium precursor solution under stirring to obtain a homogeneous mixture. A predetermined amount of a co-catalyst is separately mixed in a third fluid medium to obtain a co-catalyst solution. The co-catalyst solution is added to the homogeneous mixture under stirring to obtain the catalyst composition.
The process is described in detail.
In a first step, a solution of a second ligand is prepared by dissolving the second ligand in a first fluid medium and adding a first ligand to the solution to obtain a first mixture.
In an embodiment of the present disclosure, the first ligand is a PNP ligand of Formula I

wherein X is selected from

In an embodiment of the present disclosure, X is isopropyl.
In an embodiment of the present disclosure, the first ligand is a phosphorus-nitrogen-phosphorus (PNP) ligand of Formula Ia

In an embodiment of the present disclosure, the second ligand is at least one selected from the group consisting of triphenyl phosphine, diphenylphosphine, borane diphenylphosphine complex, chlorodiphenylphosphine, diphenyl phosphoryl chloride, tricyclohexylphosphine, 4-(diphenylphosphino)styrene, diphenylvinylphosphine, allyldiphenylphosphine, diphenyl-2-pyridylphosphine, and 4-(dimethylamino)phenyldiphenylphosphine.
In an embodiment of the present disclosure, the second ligand is triphenyl phosphine (PPh3).
The catalyst composition of the present disclosure is a mixture of PNP ligand and a phosphine donor second ligand, facilitated by smaller steric bulk, displays very good activity and superior selectivity towards 1-octene (more than 80%).
In an embodiment of the present disclosure, an amount of the first ligand is in the range of 10 mass% to 20 mass% with respect to the total mass of the first mixture. In an exemplary embodiment, the amount of the second ligand is 12.8 mass% with respect to the total mass of the first mixture.
In an embodiment of the present disclosure, the amount of the second ligand in the first mixture is in the range of 60 to 70% with respect to the total amount of the first mixture. In an exemplary embodiment, the amount of second ligand in the solution is 65% with respect to the total amount of the first mixture.
In an embodiment of the present disclosure, the first fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane. In an exemplary embodiment, the first fluid medium is toluene. In another exemplary embodiment, the first fluid medium is cyclohexane.
In a second step, a chromium precursor is separately added in a second fluid medium to obtain a chromium precursor solution.
In an embodiment of the present disclosure, the chromium precursor is selected from the group consisting of CrCl3, chromium (acetylacetonate)3, chromium (nitrate)3, and chromium (acetate)3. In an exemplary embodiment the chromium precursor is chromium (acetylacetonate)3 [Cr(acac)3].
In an embodiment of the present disclosure, the second fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane. In an exemplary embodiment, the second fluid medium is toluene. In another exemplary embodiment, the second fluid medium is cyclohexane.
In an embodiment of the present disclosure, a mass ratio of the chromium precursor to the second fluid medium is in the range of 1:1 to 2:1. In an exemplary embodiment the mass ratio of the chromium precursor to the second fluid medium is 1.22:1.
In a third step, the first mixture is added to the chromium precursor solution under stirring to obtain a homogeneous mixture.
In an embodiment of the present disclosure, the predetermined amount of the first ligand is in the range of 10 mass% to 45 mass% with respect to the total mass of the homogeneous mixture. In an exemplary embodiment, the predetermined amount of the first ligand is 39.7 mass% with respect to the total mass of the homogeneous mixture.
In an embodiment of the present disclosure, the predetermined amount of the second ligand is in the range of 10 mass% to 20 mass% with respect to the total mass of the homogeneous mixture. In an exemplary embodiment, the predetermined amount of the second ligand is 15.75 mass% with respect to the total mass of the homogeneous mixture.
In an embodiment of the present disclosure, a ratio of the chromium precursor solution to the first mixture is in the range of 0.5:1 to 1:2. In an exemplary embodiment the ratio of the chromium precursor solution to the first mixture is 1:1.
In an embodiment of the present disclosure, the first mixture and the chromium precursor are mixed at a temperature in the range of 30 °C to 35 °C for a time period in the range of 2 minutes to 30 minutes.
In an exemplary embodiment, the first mixture and the chromium precursor are mixed at 35 °C for 10 minutes.
In an embodiment of the present disclosure, an amount of the chromium precursor is in the range of 10 mass% to 20 mass% with respect to the total mass of the homogeneous mixture. In an exemplary embodiment, the amount of the chromium precursor is 18.6 mass% with respect to the total mass of the homogeneous mixture.
In a fourth step, a predetermined amount of a co-catalyst is separately mixed in a third fluid medium to obtain a co-catalyst solution.
In an embodiment of the present disclosure, the third fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane. In an exemplary embodiment, the third fluid medium is toluene. In another exemplary embodiment, the third fluid medium is cyclohexane.
In an embodiment of the present disclosure, the co-catalyst is selected from the group consisting of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and polymethylaluminoxane (PMAO). In an exemplary embodiment, the co-catalyst is methylaluminoxane (MAO).
In an embodiment of the present disclosure, the predetermined amount of the co-catalyst is in the range of 5 mass% to 15 mass% with respect to the total mass of the co-catalyst solution. In an exemplary embodiment, the predetermined amount of the co-catalyst is 10% with respect to the total mass of the co-catalyst solution.
In an embodiment of the present disclosure, a molar ratio of the co-catalyst to the chromium precursor is in the range of 300:1 to 600:1. In an exemplary embodiment, the molar ratio of the co-catalyst to the chromium precursor is 300:1. In another exemplary embodiment, the molar ratio of the co-catalyst to the chromium precursor is 500:1.
In a fifth step, the co-catalyst solution is added to the homogeneous mixture under stirring to obtain the catalyst composition.
In an embodiment of the present disclosure, the co-catalyst solution and the homogeneous mixture are mixed at a temperature in the range of 20 °C to 40 °C for a time period in the range of 2 minutes to 10 minutes.
In an exemplary embodiment, the co-catalyst solution and the homogeneous mixture are mixed at 25 °C for 5 minutes.
In an embodiment of the present disclosure, the process comprises the following steps:
i) preparing a solution of triphenyl phosphine (PPh3) by dissolving triphenyl phosphine in toluene and adding a PNP ligand of Formula Ia to the solution to obtain a first mixture;

ii) separately mixing predetermined amounts of chromium (acetylacetonate)3 and toluene to obtain a chromium precursor solution;
iii) adding the first mixture to the chromium precursor solution under stirring at a temperature in the range of 30 °C to 35 °C for a time period in the range of 2 minutes to 30 minutes to obtain a homogeneous mixture;
iv) separately mixing predetermined amounts of methylaluminoxane (MAO) and toluene to obtain a co-catalyst solution; and
v) adding the co-catalyst solution to the homogeneous mixture under stirring at a temperature in the range of 20 °C to 40 °C for a time period in the range of 2 minutes to 10 minutes to obtain the catalyst composition.
In still another aspect the present disclosure relates to a process for oligomerization. The process comprises contacting at least one olefinic monomer with the catalyst composition at a temperature in the range of 30 °C to 45 °C for a time period in the range of 30 minutes to 90 minutes to obtain 80 to 90% 1-octene.
In an exemplary embodiment, the temperature is 35 °C. In another exemplary embodiment, the temperature is 40 °C.
In an exemplary embodiment the amount of 1-octene obtained is 87%.
In an exemplary embodiment, the time period is 60 minutes.
In an embodiment of the present disclosure, the olefinic monomer is at least one selected from ethylene monomer, and 1-butene monomer. In an exemplary embodiment, the olefinic monomer is ethylene monomer.
In an embodiment of the present disclosure, the process comprises contacting ethylene with the catalyst composition, at a temperature in the range of 30 °C to 45 °C for a time period in the range of 30 minutes to 90 minutes to obtain 80 to 90% 1-octene.
The ethylene oligomerization by using the catalyst composition of the present disclosure provides high selectivity and productivity of 1-octene (more than 80%) while giving minimum undesirable by-products such as polyethylene and C10+ olefin. While the conventional catalysts show a maximum selectivity of 70% to 75%.
The catalyst composition of the present disclosure overcomes the limitation of less selectivity by providing a new catalyst system, wherein the presence of additional PPh3 ligand forming a complex and provides the advantages of high productivity and selectivity at ambient temperatures. The higher selectivity for 1-octene is probably due to steric bulk, and not the basicity on nitrogen. Further, the catalyst composition of the present disclosure facilitated by smaller steric bulk displays very good activity and superior selectivity towards 1-octene under ambient conditions. Therefore, the catalyst composition used during the oligomerization process provides high selectivity of 1-octene synthesis with high conversion of ethylene thereby forming less side products (other oligomers).
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light 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.
EXPERIMENTAL DETAILS
Experiment 1: A process for the preparation of catalyst composition in accordance with the present disclosure
Example 1: Preparation of the catalyst composition having MAO/Cr molar ratio of 500:1
5.2 mg of triphenyl phosphine (second ligand) was added in 10 mL toluene to obtain a solution of triphenyl phosphine. 26.5 mg of (phenyl)2PN(isopropyl)P(phenyl)2 ligand of Formula Ia (first ligand) was added to the so obtained solution of triphenyl phosphine to obtain a first mixture. separately, in a Schlenk vessel 10.5 mg chromium (acetylacetonate)3 was added in 10 mL toluene to obtain chromium ( acetylacetonate)3 precursor solution. The first mixture was added to the so obtained chromium precursor solution under stirring at 25 °C for 5 minutes to obtain a homogeneous mixture. Separately, 8.7 mL of 10% methylaluminoxane (MAO) (co-catalyst) solution was added to 140 mL of toluene to obtain a co-catalyst solution. The co-catalyst solution was added to the homogeneous mixture under stirring at 25 °C for 5 minutes to obtain the catalyst composition. A ratio of MAO/Cr was 500.
Experiment 2: A process for the oligomerization of ethylene by using the catalyst composition of the present disclosure
Example 2:
Ethylene oligomerization was carried out in 450 mL stainless steel vessel reactor system equipped with a propeller like stirrer with a stirring speed of 900 rpm and injection barrel. The catalyst composition obtained in Example 1 was transferred to the reactor at 35 °C followed by immediate passing of ethylene at a pressure of 30.0 kg for 60 minutes. After 60 minutes, the ethylene flow was stopped and excess ethylene was removed through a vent. The reaction was terminated by adding 50 mL 10% HCl solution in methanol to the reactor vessel to obtain a reaction mixture. The liquid reaction products (a mixture of 1-octene and 1-hexene) were separated from the solid polymer by-products by filtration and weighed. The solid polymer by-products were washed with 100 mL methanol and dried in oven at 60 °C and weighed. In the filtrate, the upper layer was separated by a separating funnel. The separated upper layer was subjected for GC analysis for quantification of different alpha-olefin products.
Examples 3 to 6:
The oligomerization process of Example 2 was repeated by varying the oligomerization temperature in the range of 25 °C to 45 °C. The effect of reaction temperature is summarized in Table 1.
Examples 7 and 8:
The oligomerization process of Example 2 was repeated by varying the oligomerization in the absence of the second ligand at a temperature of 35 °C and 45 °C respectively. The results are summarized in Table 1.
Table 1: the effect of reaction temperature for ethylene tetramerization reactions in toluene
First Ligand (mg) Second Ligand (mg) Temperature (°C) Polymer by product (grams) 1-Hexene (mass%) 1-octene (mass%) C10 + olefin by-products (mass%) Total Oligomer (in mL)
Example 2 21.5 5.6 35 0.5 9.6 87.0 3.4 60
Example 3 21.5 5.6 25 3 8.4 77.0 15.6 80
Example 4 21.5 5.6 30 2 10.4 83.0 6.5 75
Example 5 21.5 5.6 40 0.9 17.7 78.5 3.8 30
Example 6 21.5 5.6 45 1 16.2 68.3 15.5 25
Example 7 26.5 - 35 1.5 16.1 76.60 8.31 40
Example 8 26.5 - 45 1 26.31 67.43 6.26 20
From the above experiments, it was clear that upon activation with methylaluminoxane (MAO), the catalyst composition in accordance with Example 2 of the present disclosure i.e. PNP ligand with second donor triphenyl phosphine PPh3 and Cr(acac)3 exhibited high 1-octene selectivity and productivity while giving minimum undesirable polyethylene and C10+ olefin by-products as summarized in Table 1. Using toluene as a solvent at 35 °C led to a remarkable a-olefin (1-hexene and 1-octene) selectivity (greater than 90 mass%).
Examples 9 to 11:
The oligomerization process of Example 2 was repeated by varying the MAO/Cr ratio. The effect of different MAO/Cr ratio is summarized in Table 2.
Table 2: Effect of different MAO/Cr ratio on reaction products
MAO/Cr ratio Polymer by products (in grams) 1-Hexene (mass%) 1-Octene (mass%) C10+ olefin by-products (mass%) Total Oligomer (in mL)
Example 2 500 0.5 9.6 87.0 3.4 50
Example 9 300 2 5.4 78.6 15.9 30
Example 10 700 7 1.3 59.0 39.7 20
Example 11 1000 8 2.1 56.0 39.8 18
Under identical conditions, different molar ratios of MAO/Cr were studied and it was found that MAO/Cr ratio 500 displayed highest reactivity with lowest by products, at 35 °C in toluene solvent as shown in Table 2.
Examples 12 to 16:
The oligomerization process of Example 2 was repeated by replacing the solvent toluene with cyclohexane and by varying the reaction temperature in the range of 25 °C to 45 °C. The effect of the reaction temperature in cyclohexane is summarized in Table 3.
Table 3: Effect of varying temperature in cyclohexane solvent on reaction products
Temperature (in °C) Pressure (in bar) Polymer (in gm) 1-Hexene (mass%) 1-Octene (mass%) C10+ olefin by-products (mass%)
Example 12 25 30 4.0 8.4 74.0 17.6
Example 13 30 30 0.8 9.7 72.0 18.3
Example 14 35 30 1.0 12.6 68.3 19.1
Example 15 40 30 0.7 15.40 75.2 9.4
Example 16 45 30 0.6 8.8 80.8 11.2
The catalyst composition of Example 2 was studied in cyclohexane solvent and it was found that selectivity for 1-octene decreased on increasing the temperature till 35 °C, while further increasing the temperature the selectivity increases up to 80%. However, highest selectivity for 1-octene was observed with toluene at 35 °C, as shown in Table 1.
These findings clearly indicated that the two different donors of the catalyst composition of the present disclosure increase the selectivity towards 1-octene at lower temperature and show much better activity than the other PNP ligands.
The catalyst composition according to the present disclosure provides selective synthesis of 1-octene with minimum by-products. The catalyst composition of the present disclosure is a combination of ligands such as PNP tridentates ligand and triphenyl phosphine ligand, which enabled the selective production of 1-octene (more than 80% yield) at a temperature in the range of 30 °C to 35 °C. The other known catalysts such as N aryl functionalized PNP ligand, PNP with different derivatives, diphosphinomine ligands and the like do not provide such selectivity at ambient temperature.
The reaction temperature and solvent system had a remarkable ability of switching the selectivity of 1-octene, from lower to higher. Different MAO/Cr ratio for oligomerization also had significant effect on 1-octene selectivity.
The catalyst of the present disclosure facilitated the oligomerization reaction at ambient temperature (30 °C to 35 °C) with 87% selectivity for 1-octene, which is comparatively higher when compared with the other reported catalyst composition.
TECHNICAL ADVANCEMENTS
The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of
? a catalyst composition for oligomerization that;
• has high selectivity and productivity for 1-octene; and
• produces 1-octene with minimum undesirable side products; and
? a process of oligomerization that
• is simple, economic and one step; and
• is carried out at ambient temperatures.
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.
The economy significance details requirement may be called during the examination. Only after filing of this Patent application, the applicant can work publically related to present disclosure product/process/method. The applicant will disclose all the details related to the economic significance contribution after the protection of invention.

CLAIMS:WE CLAIM:

1. A catalyst composition comprising:
a) a chromium precursor;
b) a first ligand;
c) a second ligand;
d) a co-catalyst; and
e) a fluid medium.

2. The catalyst composition as claimed in claim 1, wherein
i. said chromium precursor is present in an amount in the range of 2 to 10 mass%;
ii. said first ligand is present in an amount in the range of 10 to 20 mass%;
iii. said second ligand is present in an amount in the range of 1 to 5 mass%;
iv. said co-catalyst is present in an amount in the range of 2 to 6 mass%; and
v. said fluid medium is present in an amount in the range of 65 to 75 mass%,
wherein the mass% of each component is with respect to the total mass of said catalyst composition.

3. The catalyst composition as claimed in claim 1, wherein
a) said chromium precursor is present in an amount in the range of 6 mass% to 7 mass%;
b) said first ligand is present in an amount in the range of 15 mass% to 16 mass%;
c) said second ligand is present in an amount in the range of 3 mass% to 4 mass%;
d) said co-catalyst is present in an amount in the range of 4 mass% to 5 mass%; and
e) said fluid medium is present in an amount in the range of 70 mass% to 71 mass%,
wherein the mass% of each component is with respect to the total mass of said catalyst composition.

4. The catalyst composition as claimed in claim 1, wherein said chromium precursor is selected from the group consisting of CrCl3, chromium (acetylacetonate)3, chromium (nitrate)3, and chromium (acetate)3.

5. The catalyst composition as claimed in claim 1, wherein said chromium precursor is chromium (acetylacetonate)3.

6. The catalyst composition as claimed in claim 1, wherein said first ligand is a phosphorus-Nitrogen-Phosphorus (PNP) ligand of Formula I

wherein X is selected from

7. The catalyst composition as claimed in claim 6, wherein X is isopropyl.

8. The catalyst composition as claimed in claim 1, wherein said first ligand is a PNP ligand of Formula Ia

9. The catalyst composition as claimed in claim 1, wherein said second ligand is at least one selected from the group consisting of triphenyl phosphine, diphenylphosphine, borane diphenylphosphine complex, chlorodiphenylphosphine, diphenyl phosphoryl chloride, tricyclohexylphosphine, 4-(diphenylphosphino)styrene, diphenylvinylphosphine, allyldiphenylphosphine, diphenyl-2-pyridylphosphine, 4-(dimethylamino)phenyldiphenylphosphine and 4-(dimethylamino)phenyldiphenylphosphine.

10. The catalyst composition as claimed in claim 1, wherein said second ligand is triphenyl phosphine (PPh3).

11. The catalyst composition as claimed in claim 1, wherein said co-catalyst is selected from the group consisting of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and polymethylaluminoxane (PMAO).

12. The catalyst composition as claimed in claim 1, wherein said co-catalyst is methylaluminoxane (MAO).

13. The catalyst composition as claimed in claim 1, wherein said fluid medium is at least one selected from the group consisting of toluene, cyclohexane, hexane, and isopentane.

14. The catalyst composition as claimed in claim 1, wherein a molar ratio of said co-catalyst to said chromium precursor is in the range of 300:1 to 600:1.

15. A process for the preparation of a catalyst composition, said
process comprising the following steps:
i) preparing a solution of a second ligand by dissolving said second ligand in a first fluid medium and adding a first ligand to said solution to obtain a first mixture;
ii) separately mixing predetermined amounts of a chromium precursor and a second fluid medium to obtain a chromium precursor solution;
iii) adding said first mixture to said chromium precursor solution under stirring to obtain a homogeneous mixture;
iv) separately mixing predetermined amounts of a co-catalyst and a third fluid medium to obtain a co-catalyst solution; and
v) adding said co-catalyst solution to said homogeneous mixture under stirring to obtain said catalyst composition.

16. The process as claimed in claim 15, wherein said first ligand is a PNP ligand of Formula I

wherein X is selected from

17. The process as claimed in claim 16, wherein X is isopropyl.

18. The process as claimed in claim 15, wherein said first ligand is a PNP ligand of Formula Ia

19. The process as claimed in claim 15, wherein said second ligand is at least one selected from triphenyl phosphine, diphenylphosphine, borane diphenylphosphine complex, chlorodiphenylphosphine, diphenyl phosphoryl chloride, tricyclohexylphosphine, 4-(diphenylphosphino)styrene, diphenylvinylphosphine, allyldiphenylphosphine, diphenyl-2-pyridylphosphine, and 4-(dimethylamino)phenyldiphenylphosphine.

20. The process as claimed in claim 15, wherein said second ligand is triphenyl phosphine (PPh3).

21. The process as claimed in claim 15, wherein said chromium precursor is selected from the group consisting of CrCl3, chromium (acetylacetonate)3, chromium (nitrate)3, and chromium (acetate)3.

22. The process as claimed in claim 15, wherein said co-catalyst is selected from the group consisting of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), and polymethylaluminoxane (PMAO).

23. The process as claimed in claim 15, wherein
• said first fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane;
• said second fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane; and
• said third fluid medium is selected from the group consisting of toluene, cyclohexane, hexane, and isopentane.

24. The process as claimed in claim 15, wherein
• said predetermined amount of said first ligand is in the range of 10 mass% to 45 mass%;
• an amount of said second ligand is in the range of 10 mass% to 20 mass%; and
• an amount of said chromium precursor is in the range of 10 mass% to 20 mass%;
wherein said mass% are with respect to the total mass of the homogeneous mixture.

25. The process as claimed in claim 15, wherein
• said first mixture and said chromium precursor are mixed at a temperature in the range of 30 °C to 35 °C for a time period in the range of 2 minutes to 30 minutes;
• said co-catalyst solution and said homogeneous mixture are mixed at a temperature in the range of 20 °C to 40 °C for a time period in the range of 2 minutes to 10 minutes; and
• said predetermined amount of said co-catalyst is in the range of 5 to 15 mass% with respect to the total mass of the co-catalyst solution.

26. The process as claimed in claim 15, wherein a molar ratio of said co-catalyst to said chromium precursor is in the range of 300:1 to 600:1.

27. The process as claimed in claim 15, wherein said process comprising the following steps:
i) preparing a solution of triphenyl phosphine (PPh3) by dissolving triphenyl phosphine in toluene and adding a PNP ligand of Formula Ia to said solution to obtain a first mixture;

ii) separately mixing predetermined amounts of chromium (acetylacetonate)3 and toluene to obtain a chromium precursor solution;
iii) adding said first mixture to said chromium precursor solution under stirring at a temperature in the range of 30 °C to 35 °C for a time period in the range of 2 minutes to 30 minutes to obtain a homogeneous mixture;
vi) separately mixing predetermined amounts of methylaluminoxane (MAO) and toluene to obtain a co-catalyst solution; and
vii) adding said co-catalyst solution to said homogeneous mixture under stirring at a temperature in the range of 20 °C to 40 °C for a time period in the range of 2 minutes to 10 minutes to obtain said catalyst composition.

28. A process for oligomerization comprising contacting at least one olefinic monomer with a catalyst composition as claimed in claim 1, at a temperature in the range of 30 °C to 45 °C for a time period in the range of 30 minutes to 90 minutes to obtain 80 to 90% 1-octene.

29. The process as claimed in claim 28, wherein said olefinic monomer is at least one selected from the group consisting of ethylene, 1-butene monomer.

30. The process as claimed in claim 28, wherein said process comprises contacting ethylene with said catalyst composition as claimed in claim 1, at a temperature in the range of 30 °C to 45 °C for a time period in the range of 30 minutes to 90 minutes to obtain 80 to 90% 1-octene.

Dated this 03rd day of August, 2024

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, MUMBAI