Claims:1. A Ziegler-Natta catalyst composition for olefin polymerization, said catalyst composition comprising:
? a pro-catalyst comprising at least one magnesium compound, at least one titanium component and at least one internal electron donor; wherein, said at least one internal electron donor is selected from the group consisting of Formula(I), Formula(II), Formula(III), Formula(IV) and Formula(V);

Formula (I) Formula (II) Formula (III)

Formula (IV) Formula (V)
wherein, R and R1 are at least one independently selected from the group consisting of C1-C8 linear or branched alkyl and arylalkyl groups;
? at least one organo-aluminium co-catalyst; and
? at least one fluid medium.
2. The composition as claimed in claim 1, wherein said magnesium compound is at least one selected from the group consisting of magnesium methoxide, magnesium ethoxide, magnesium propoxide, magnesium isopropoxide and magnesium butoxide.
3. The composition as claimed in claim 1, wherein said organoaluminum co-catalyst is at least one selected from the group consisting of triethylaluminium, tridecylaluminium, tri-n-butylaluminium, tri isopropylaluminium, tri-isoprenylaluminium, tri-isobutylaluminium, ethyl aluminium sesquichloride, diethylaluminium chloride, di-isobutyl aluminium chloride, triphenylaluminium, tri-n-octylaluminium and tri-n-decylaluminium.
4. The composition as claimed in claim 1, wherein said fluid medium is at least one selected from the group consisting of hexane, toluene, benzene and ethylbenzene.
5. The composition as claimed in claim 1, wherein the ratio of the amount of said at least one internal electron donor and magnesium is in the range of 1:1 to 1:4.
6. The composition as claimed in claim 1, wherein the ratio of the amount of aluminum and the amount of titanium in the composition is in the range of 50 to 200.
7. A process for polymerization of at least one olefin in the presence of the composition as claimed in claim 1, said process comprising the following steps:
a. charging a predetermined amount of the Ziegler-Natta catalyst composition to a reactor under nitrogen atmosphere;
b. introducing at least one olefin in said slurry up to a predetermined pressure to obtain a mixture;
c. heating said mixture in the temperature range of 50 to 90 °C for a time period in the range of 1 to 5 hours to obtain a heated mixture comprising a co-polymer;
d. cooling and filtering said heated mixture to obtain a residue and a filtrate; and
e. drying said residue to obtain the polymer. , Description:FIELD
The present disclosure relates to a Ziegler-Natta catalyst composition and a process for preparation thereof.
BACKGROUND
Ziegler-Natta catalyst compositions are used in the synthesis of polymers from olefins. Ziegler-Natta catalyst compositions typically comprise a pro-catalyst, a co-catalyst and at least one electron donor. The electron donors can be internal electron donors and external electron donors. The electron donors affect the activity of the catalyst and the stereo-regularity of the polymer formed during the polymerization process. However, the use of an external electron donor adds to the cost of the process.
The use of external electron donor also increases the number of chemicals used, thereby increasing the complexity of the process.
The morphology of the catalyst precursor is replicated in the polymer resin via the catalyst, which is synthesized from the precursor. A controlled particle size and morphology of the catalyst produces a desired particle size of the polymer due to replication of the precursor morphology into the catalyst and eventually to the polymer. This gives better flowability and hence results into better working of plant throughout.
Therefore, there is felt a need to provide a Ziegler-Natta catalyst composition that can be used for the polymerization process without adding an external electron donor.
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 Ziegler-Natta catalyst composition.
Another object of the present disclosure is to provide a Ziegler-Natta catalyst composition for polymerization of olefins.
Still another object of the present disclosure is to provide a process for co-polymerization of olefins.
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 Ziegler-Natta catalyst for olefin polymerization. The catalyst composition of the present disclosure comprises:
- at least one pro-catalyst comprising at least one magnesium compound, at least one titanium component and at least one internal electron donor; wherein, at least one internal electron donor is selected from the group consisting of Formula(I), Formula(II), Formula(III), Formula(IV) and Formula(V);

Formula (I) Formula (II) Formula (III)

Formula (IV) Formula (V)
wherein, R and R1 are at least one independently selected from a group consisting of C1-C8 linear or branched alkyl and arylalkyl groups;
? at least one organo-aluminium co-catalyst; and
? at least one fluid medium.
The catalyst composition of the present disclosure can be used for co-polymerization of olefins. The process of polymerization of the present disclosure can be carried out without the addition of an external electron donor.
DETAILED DESCRIPTION
The present disclosure will now be described with reference to the accompanying embodiments which do not limit the scope and ambit of the present disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The present disclosure relates to a Ziegler-Natta catalyst composition comprising a pro-catalyst, an organoaluminum co-catalyst and a fluid medium. The Ziegler-Natta catalyst composition of the present disclosure facilitates olefin polymerization without the addition of an external electron donor and a terminating agent.
In accordance with one aspect of the present disclosure, there is provided a Ziegler-Natta catalyst composition for polymerization, the catalyst composition comprising:
? at least one pro-catalyst comprising at least one magnesium compound, at least one titanium component and at least one internal electron donor; wherein, at least one internal electron donor is selected from the group consisting of Formula(I), Formula(II), Formula(III), Formula(IV) and Formula(V);

Formula (I) Formula (II) Formula (III)

Formula (IV) Formula (V)
wherein, R and R1 are at least one independently selected from a group consisting of C1-C8 linear or branched alkyl and arylalkyl groups;
? at least one organo-aluminium co-catalyst; and
? at least one fluid medium.
The magnesium compound of the present disclosure can be at least one selected from a group consisting of magnesium methoxide, magnesium ethoxide, magnesium propoxide, magnesium butoxide and magnesium isopropoxide.
The magnesium compound of the present disclosure can be spherical in shape that facilitates in imparting a spherical nature to the particles of the polymer. The morphology of the catalyst precursor is replicated in the polyethylene via the catalyst, which is synthesized from the precursor. A controlled particle size and morphology of the catalyst produces a desired particle size of the polymer due to replication of the precursor morphology into the catalyst and eventually to the polymer. This gives better flow ability and hence results into better working of the plant throughout.
In accordance with the present disclosure, there is provided a method for the preparation of spherical magnesium alkoxide.
The process comprises reacting magnesium metal with at least one alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol and isobutanol. Iodine is added to the mixture of magnesium and alcohol as an initiator. The reaction can be accompanied by the evolution of hydrogen gas indicating the initiation of the reaction. The hydrogen gas evolution can be monitored visually. The ceasing of hydrogen evolution indicates completion of the reaction.
In accordance with the present disclosure, there is provided a process for the preparation of the pro-catalyst comprising a magnesium compound, a titanium component and at least one internal electron donor; wherein, at least one internal electron donor is selected from the group consisting of Formula(I), Formula(II), Formula(III), Formula(IV) and Formula(V);

Formula (I) Formula (II) Formula (III)

Formula (IV) Formula (V)
wherein, R and R1 are at least one independently selected from the group consisting of C1-C8 linear or branched alkyl and arylalkyl groups;
In accordance with the present disclosure, there is provided a method for the preparation of the pro-catalyst. The process is as follows:
A predetermined amount of at least one magnesium alkoxide and at least one titanium component are introduced in a reactor comprising a fluid medium to obtain a slurry. At least one internal donor is added in the slurry to obtain a first mixture. The first mixture is heated to a predetermined temperature, while stirring. After heating, the slurry is cooled to room temperature and the fluid medium is removed by decantation to obtain a first solid. Titanium component and the fluid medium are added to the first solid to obtain a second mixture. The second mixture is heated, while stirring. The second mixture is cooled and fluid medium is removed by decantation to obtain a second solid. The second solid is washed and dried to obtain the pro-catalyst.
In accordance with one embodiment of the present disclosure, magnesium alkoxide is a mixture of magnesium methoxide and magnesium ethoxide,
In accordance with one embodiment of the present disclosure, titanium component is TiCl4.
In accordance with one embodiment of the present disclosure, the fluid medium is chlorobenzene.
The organoalumnum co-catalyst of the present disclosure can be at least one selected from the group consisting of triethylaluminium, tridecylaluminium, tri-n-butylaluminium, tri isopropylaluminium, tri-isoprenylaluminium, tri-isobutylaluminium, ethyl aluminium sesquichloride, diethylaluminium chloride, di-isobutyl aluminium chloride, triphenylaluminium, tri-n-octylaluminium and tri-n-decylaluminium.
The fluid medium can be at least one selected from a group consisting of hexane, toluene, benzene and ethylbenzene.
In accordance with one embodiment of the present disclosure, the fluid medium is hexane.
In accordance with another aspect of the present disclosure, there is provided a process for co-polymerization of olefin in the presence of the Ziegler-Natta catalyst composition of the present disclosure, the process comprising:
- charging a predetermined amount of the Ziegler-Natta catalyst composition to a reactor under nitrogen atmosphere;
- introducing at least one olefin in the slurry at a predetermined pressure to obtain a mixture;
- heating the mixture in the temperature range of 50 to 90 °C for a time period in the range of 1 to 5 hours to obtain a heated mixture comprising a co-polymer;
- cooling the heated mixture and filtering to obtain a residue and a filtrate; and
- drying the residue to obtain the co-polymer.
The process of polymerization in the presence of the Ziegler-Natta catalyst composition of the present disclosure can be carried out with or without the addition of chain terminating agent.
In accordance with one embodiment of the present disclosure, the ratio of the amount of internal electron donor and magnesium is in the range of 1:1 to 1:4.
In accordance with one embodiment of the present disclosure, the ratio of the amount of aluminum and the amount of titanium in the Ziegler-Natta catalyst composition is in the range of 50 to 200.
The present disclosure is further described in light of the experiments provided herein below which are set forth for illustration purpose only and not to be construed for limiting the scope of the present disclosure. These laboratory scale experiments can be scaled up to industrial/commercial scale.
A series of pro-catalysts were prepared using at least one internal donor selected from the group consisting of Formula (I), Formula (II), Formula (III), Formula (IV) and Formula (V). The pro-catalysts prepared using at least one internal electron donors of Formula (I), Formula (II), Formula (III), Formula (IV) and Formula (V) are referred as CAT-1, CAT-2, CAT-3, CAT-4 and CAT-5 respectively.
EXPERIMENT 1: Synthesis of spherical magnesium alkoxide
A reactor was charged with 1250 mL of mixed alcohol comprising 50% methanol and 50% ethanol. 55 g of magnesium metal was added to the reactor under nitrogen atmosphere to obtain a mixture. The mixture was stirred at 450 rpm using a magnetic stirrer. After stirring for 30 minutes, 1.5 g of iodine was added to the reactor. This was immediately accompanied by the evolution of hydrogen gas indicating the initiation of the reaction. The hydrogen gas evolution was monitored visually and the temperature was increased in step wise manner from 40 to 80 °C. After the evolution of hydrogen gas ceased, the mixture of alcohols was evaporated at higher temperature to obtain a white powder of the mixture of magnesium ethoxide and magnesium methoxide.
EXPERIMENT 2: Synthesis of a pro-catalyst
A reactor was charged with 100 mL chloro-benzene. 4 g mixture of spherical magnesium ethoxide and magnesium methoxide from experiment 1 and 100 mL TiCl4 was introduced in the reactor to obtain a slurry. 1 g internal electron donor (as provided in Table 1) was added in the mixture to obtain a first mixture. The first mixture was heated to 120 °C for 90 minutes, while stirring. After heating, the slurry was cooled to room temperature and chlorobenzene was removed by decantation to obtain a first solid. 75 mL TiCl4 and 75 mL chloro-benzene was added to the first solid to obtain a second mixture. The second mixture was heated at 120 °C for 30 minutes, while stirring. The second mixture was cooled and chlorobenzene was removed by decantation to obtain a second solid. The second solid was washed with 100 mL hexane 4 times to obtain a washed solid. The washed solid was dried to obtain a pro-catalyst. The pro-catalysts synthesized using different internal electron donors are tabulated in Table 1.
Table 1: Composition of the pro-catalysts synthesized using different internal electron donors
Sr. No. pro-catalyst Internal donor Ti (%) Mg (%) Cl (%)
1 CAT-1 Pentaerythritol tetraethyl ether (Formula I) 5.09 13.8 53.9
2 CAT-2 Pentaerythritol tetra octyl ester (Formula II) 6.0 15.54 51.6
3 CAT-3 (3-Benzoyl-thioureido-) butane (Formula III)
9.1 12.8 61.79
4 CAT-4 Diethyl methyl phosphonate (Formula IV) 4.99 14.6 56.7
N-5 CAT-5
Dipentaerythritol hexaethyl ether (Formula V)
10.36 10.43 60.6
The pro-catalysts synthesized using the internal donors of the present disclosure were formulated so as to have titanium in the range of 5.09 to 10.36 wt%. Magnesium wt% of the catalysts of the present disclosure was in the range of 10.43 to 15.54 wt% and chlorine was present in the range of 51.6 to 61.79 wt%.
EXPERIMENT 3: Homo-polymerization of olefin
Different weights of the pro-catalysts, as synthesized in experiment 2 were diluted with 200 mL hexane under nitrogen in a reactor. 10% solution of triethyl aluminum (TEAL) in hexane was added to the flask to obtain a Ziegler-Natta catalyst composition that appeared as a dark solution. The full homogeneous dark solution was added to a reactor at a constant propylene pressure (2.5 atm) and was heated at 70 °C for 1 hour. After 1 hour the reaction mixture was cooled down and the excess pressure was released. The polypropylene resin was taken away with fluid medium. Excess tri-ethyl aluminum was quenched with 10% HCl-MeOH mixture. The obtained polymer was filtered and dried at 60 °C for 3 hour. The results obtained by using varying amounts of the pro-catalysts of Experiment 2 are tabulated in Table 2.
Table 2: Homo-polymerization of olefin
Catalyst TEAL (mL) Weight of pro-catalyst (mg) External Electron Donor (organosilane) (µL) Yield of the polymer(Kg/gCat) Melting point (°C) of the polymer
CAT-1
10 45 0 2.7 159
12 30 0 2.2 158
10 45 10 1.2 158
CAT-2
10 60 -- 1.5 158
10 35 -- 1.4 158
10 35 5 1.1 158
CAT-3 10 60 -- 1.2 158
12 40 -- 1.1 157
CAT-4 10 40 -- 2.2 158
20 40 10 2.1 156
CAT-5 10 65 -- 1 156

The synthesized catalyst compositions were used for the homo-polymerization of propylene. The amount of the organoaluminum co-catalyst “triethyl aluminum” was varied from 10 to 20 mL. The weight of the pro-catalyst was varied from 35 to 65 mg. The maximum yield of 2.7 kg/g cat was obtained for CAT-1, without the use of an external electron donor. The yield for the series of catalysts of the present disclosure was found to be in the range of 1 to 2.7 kg/g cat.
EXPERIMENT 4: Co-polymerization of propylene and 1-hexene
The pro-catalyst, as synthesized in experiment 2 was diluted with 200 mL hexane under nitrogen in a reactor. 10% TEAL solution in hexane was added to the flask to obtain a Ziegler-Natta catalyst composition that appeared as a dark solution. Required amount of 1-hexene was added inside the reactor. The full homogeneous dark solution was added to the reactor at constant propylene pressure (2.5 atm) and was heated at 70 °C for 1 hour. After 1 hour the reaction mixture was cooled down and the excess pressure was released. The polypropylene resin was taken away with fluid medium. Excess tri-ethyl aluminum was quenched with 10% HCl-MeOH mixture. The obtained polymer was filtered and dried at 60 °C for 3 hours.
Table 3: Co-polymerization of olefins
Catalyst TEAL (mL) Weight of catalyst (mg) 1-Hexene (mL) 1-Octene (mL) Yield of the polymer (Kg/gCat) Melting temperature of the polymer (°C)
CAT-1 10 45 10 -- 1.6 142
CAT-2 10 35 20 -- 1.1 137
10 35 -- 20 1.2 142
10 35 40 -- 1.3 138
10 35 10 -- 1.2 139
CAT-3 10 40 10 -- 0.5 143
10 40 20 -- 0.6 142
10 40 10 -- 0.4 137
10 40 5 -- 0.3 146
CAT-4 10 40 10 -- 1.4 139
10 40 10 -- 1.0 144
CAT-5 20 65 20 -- 0.8 132
10 65 20 -- 0.9 132
10 65 -- -- 0.5 132
10 65 40 -- 0.5 132

The synthesized Ziegler-Natta catalysts of Experiment 2 were used for the co-polymerization of propylene with 1-hexene or 1-octene. Highest yield for the co-polymer of propylene with 1-hexene was found to be 1.6 kg/g Cat prepared using CAT-1. Yield of 1.2 kg/g cat was obtained for co-polymer of propylene with 1-octene prepared in the presence of CAT-2.
High yield of the polymer was obtained in the absence of an external electron donor. The process of polymerization was carried out in the absence of a chain terminating agent; however, the process of polymerization can also be carried out in the presence of a chain terminating agent.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including but not limited to the realization of: a Ziegler-Natta catalyst composition that can be used for copolymerization of olefins
? in the absence of an external electron donors; and.
? an economical process for polymerization.
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.