CLIAMS:1. A process for preparing a pro-catalyst for use in polymerization of olefins; said process comprising the following steps:
a. reacting magnesium metal with a mixture of at least two alcohols in the presence of at least one initiator to obtain a catalyst precursor having the general formula Mg [(OR1)2-x(OR2 )x]; and
b. treating said catalyst precursor with a chlorinating medium in the presence of at least one fluid medium and at least one internal donor to obtain the pro-catalyst,
wherein, one of OR1 and OR2 is methoxy and the other one is selected from the group consisting of ethoxy, propoxy, butoxy and pentoxy and the methoxy content in the catalyst precursor ranges from 0.01 to 8% by weight of the pro-catalyst.

2. The process as claimed in claim 1, wherein the exothermicity during the reaction between (Mg[(OR1)2-x(OR2)x]) and the chlorinating medium is inversely proportional to the methoxy content.

3. The process as claimed in claim 1, wherein the mixture of alcohols comprise methanol and ethanol.

4. The process as claimed in claim 3, wherein the molar ratio of methanol to ethanol ranges from 0.01 to 0.1

5. The process as claimed in claim 1, wherein the molar ratio of magnesium to the mixture of alcohols ranges from 0.05 to 0.1.

6. The process as claimed in claim 1, wherein the initiator is iodine and the chlorinating medium is titanium tetrachloride.
7. The process as claimed in claim 1, wherein the fluid medium is chlorobenzene and the internal donor is di-isobutyl phthalate.

8. The process as claimed in claim 1, wherein the molar ratio of said catalyst precursor and said chlorinating medium ranges from 0.08 to 0.3.

9. A pro-catalyst prepared in accordance with claims 1 to 8, wherein said pro-catalyst is characterized by particle size breakage index ranging from 1.0 to 1.3.

10. The pro-catalyst as claimed in claim 9, wherein the pro-catalyst has a particle size ranging from 22 µm to 30 µm. ,TagSPECI:Field
The present disclosure relates to a process for preparing a pro-catalyst that can be employed in the polymerization of olefins.

Background
The morphology of magnesium dichloride supported titanium catalyst plays an important role in the production of polypropylene with desired morphological properties. The morphology of the catalyst precursor is replicated in polyolefin resin via the catalyst which is synthesized from the catalyst precursor.
To produce a catalyst particle with desired morphology, the rate of reaction between the catalyst precursor and the chlorinating medium such as titanium tetrachloride and chlorobenzene, during the synthesis of the catalyst is required to be controlled. The reaction between a pure catalyst precursor (magnesium alkoxide) and titanium tetrachloride is highly reactive and exothermic which leads to uncontrolled heat generation. The stress created by the generation of uncontrolled heat of reaction leads to the formation of non-uniform size particles having a very high breakage index and less mechanical strength of the particles which generates high amounts of fines when used for polymerization of olefins.
US8633124 suggests that the concentration of methoxy content used in the preparation of the catalyst affects the mechanical strength of the catalyst particle. However, it has been observed that generation of fines is higher when the disclosure of US8633124 is practiced because of the uncontrolled exothermic reaction.
Fines are generated due to the chemical and the mechanical attrition of catalyst during the titanation and washing stages and may be due to the higher reactivity of the catalyst precursor towards titanium fluid medium (titanation solvent).
Therefore, there is felt need for reduction of exothermicity of the reaction between the catalyst precursor and the titanium tetrachloride during catalyst synthesis to get a uniform sized catalyst particle with increased strength.

Objects
Some of the objects of the present disclosure which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

Another object of the present disclosure is to provide a process for preparing a pro-catalyst for effective polymerization.

Still another object of the present disclosure is to provide a process for preparing a pro-catalyst which has a controlled morphology.

Yet another object of the present disclosure is to provide a process for preparing a pro-catalyst with controlled morphology, for use in preparing polyolefins of desired morphology.
Still another object of the present disclosure is to provide an optimized amount of methoxy content for retaining the morphology of the pro-catalyst particle.

Yet another object of the present disclosure is to provide a process for preparing a pro-catalyst that has comparatively low exothermicity.

Still another object of the present disclosure is to provide a process for preparing a pro-catalyst that produces comparatively less amount of fines during polymerization of olefins.

Another object of the present disclosure is to provide a pro-catalyst that has improved mechanical strength and narrow particle size distribution.
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
A process for preparing a pro-catalyst that can be used in the polymerization of olefins involve the steps of reacting magnesium metal with a mixture of at least two alcohols in the presence of at least one initiator to obtain a catalyst precursor having the general formula Mg [(OR1)2-X(OR2)x], wherein, one of OR1 and OR2 is methoxy and the other one is selected from the group consisting of ethoxy, propoxy, butoxy and pentoxy, and the methoxy content in the catalyst precursor ranges from 0.01 to 8% by weight; and treating the catalyst precursor with a chlorinating medium in the presence of at least one fluid medium and at least one internal donor to obtain the pro-catalyst.
The catalyst precursor obtained from the process of the present disclosure is characterized by 0.01 to 8 wt% of methoxy content.
The pro-catalyst obtained from the process of the present disclosure is characterized by the particle size breakage index ranging from 1.0 to 1.3.
The so obtained catalyst precursor has a controlled morphology for preparing the pro-catalyst.
The resultant pro-catalyst exhibits the desired morphology due to a controlled exothermic reaction between magnesium alkoxide and titanium tetrachloride.
Further, when the polyolefin resin is prepared in the presence of the pro-catalyst having controlled morphology, the resultant polyolefin resin also has a controlled morphology and the formation of fines is comparatively less during polymerization.

Brief description of drawings:
The process of the present disclosure will now be described with the help of the accompanying drawings, in which:
Figure 1 illustrates the graph of exothermicity trend of a pro-catalyst when the catalyst precursor is magneisum ethoxide (0% methoxy content);
Figure 2 illustrates the graph of exothermicity trend of a pro-catalyst when the catalyst precursor is magneisum methoxide (100% methoxy content);
Figure 3 illustrates the graph of exothermicity trend of a pro-catalyst when the catalyst precursor is magneisum alkoxide with 3% of methoxy content;
Figure 4 illustrates the graph of exothermicity trend of a pro-catalyst when the catalyst precursor is magneisum alkoxide with 8% of methoxy content;
Figure 5 illustartes the morphological SEM images of System 1 where, the catalyst precursor is pure magnesium ethoxide;
Figure 6 illustrates the morphological SEM images of System 2 where, the catalyst precursor is pure magnesium methoxide;
Figure 7 illustrates the morphological SEM images of System 3 where, the catalyst precursor is magnesium alkoxide with 3% of methoxy content; and
Figure 8 illustrates the morphological SEM images of System 4 where, the catalyst precursor is magnesium alkoxide with 8% of methoxy content.

Detailed Description
The reaction of magnesium alkoxide with titanation solvent (titanation fluid medium) is highly exothermic. The higher exothermicity of the reaction reduces the strength of the catalyst particles, which in turn results in the formation of comparatively more fines during the polymerization process of olefins.
Therefore, in order to overcome the above mentioned drawbacks, the inventors of the present disclosure have envisaged a process for preparing a pro-catalyst that is less exothermic in order to produce a pro-catalyst that has a controlled morphology.
Furthermore, the inventors have optimized the methoxy content of magnesium alkoxide precursor to obtain the pro-catalyst with narrow particle size distribution and high strength.
The present disclosure provides a process for preparing a pro-catalyst, used in producing polyolefins, involving the following steps.
In the first step of the reaction of the present disclosure, magnesium metal powder is added to a mixture of alcohols while stirring at a speed ranging from 300 rpm to 400 rpm at a temperature ranging from 30 oC to 90 oC for 10-12 hours to obtain magnesium alkoxide (catalyst precursor) having the general formula Mg [(OR1)2-x(OR2)x] wherein one of OR1 and OR2 is methoxy and the other one is selected from the group consisting of ethoxy, propoxy, butoxy and pentoxy.
The alcohol used in the present disclosure is selected from the group consisting of C1-C4 carbon containing alcohols. Typically, the mixture of alcohols is selected from the group consisting of ethanol and methanol.
In an exemplary embodiment, the molar ratio of methanol to ethanol used in the present disclosure ranges from 0.01 to 0.1.
The stirring of magnesium powder and the mixture of alcohols is carried out in the presence of iodine. Iodine used in the present disclosure acts as an initiator to carry out the reaction. The molar ratio of magnesium to the mixture of alcohols ranges from 0.05 to 0.1.
More specifically, the stirring of magnesium powder and the mixture of alcohols is conducted in three ranges of temperature, due to the exothermicity of the reaction. In the first temperature range, the stirring of the reaction mixture (magnesium powder and mixture of alcohols) is carried out at a temperature ranging from 40 oC to 60 oC for 1 hour. In the second temperature range, the heating of the reaction mixture is carried out at a temperature ranging from 60 oC to 80 oC for 2 hours. In the third temperature range, the heating of the reaction mixture is maintained at a temperature ranging from 80 oC to 82 oC for 7 hours. The vapors of the mixture produced during the reaction are condensed in an overhead condenser. The hydrogen gas produced during the reaction is vented off and the mixture of alcohols left after the reaction is removed by filtration. The filtrate is reused for further synthesis. The solid obtained after filtration is dried in buchner funnel under vacuum to get magnesium alkoxide particles (catalyst precursor) having a bulk density ranging from 0.50-0.55 g/cc and surface area ranging from 10-12 m2/g.
In the second step of the reaction of the present disclosure, the catalyst precursor obtained from the first step is treated with a chlorinating medium in presence of at least one fluid medium and at least one internal donor, at a temperature ranging from 90 oC to 120 oC under inert atmosphere to obtain the pro-catalyst.
The catalyst precursor obtained as described herein above in the present disclosure is a compound having a general formula Mg [(OR1)2-x(OR2)x], wherein one of OR1 and OR2 is methoxy and the other one is selected from the group consisting of ethoxy, propoxy, butoxy and pentoxy.
The fluid medium used in the process of the present disclosure includes, but is not limited to, chlorobenzene, toluene, o-dichloro benzene and p-chloro toluene. The chlorinating medium comprises of titanium tetrachloride and chlorobenzene.
The molar ratio of the catalyst precursor and the chlorinating medium in the process for preparing the pro-catalyst ranges from 0.08 to 0.3.
The internal donor used in the process of the present disclosure includes, but is not limited to, di-isobutyl phthalate (DIBP), di-octyl phthalate, di-isooctyl phthalate, bis(2-ethylhexyl) phthalate, and di n-butyl phthalate.
The pro-catalyst so obtained is filtered and washed with isopentane and dried at a temperature ranging from 45 oC to 55 oC under nitrogen (inert atmosphere) to obtain a brown colored product as the pro-catalyst. The pro-catalyst has a particle size ranging from 22 µm to 30 µm.
In the present process, the afore-stated reactants are used in predetermined quantities and proportions with respect to each other.
Magnesium alkoxide (catalyst precursor) containing different amounts of methoxy content was used while reacting with the chlorinating medium to understand the reason for fines generation during the polymerization reaction. The extent of heat of reaction (exothermicity) for chlorination plays an important role in the generation of fines during the polymerization reaction.
The extent of exothermicity is monitored by measuring the temperature difference between the temperature of reaction and the bath temperature maintained at 20 °C over a period of time when the magnesium alkoxide is reacted with the chlorinating medium (TiCl4+Chlorobenzene).
The extent of heat of the reaction increases as the number of carbon atoms increased in pure magnesium alkoxide during the reaction. Some of the findings are stated below;
? When only magnesium ethoxide (0% methoxy content) is treated with the chlorinating medium, the extent of exothermicity is 12 oC to 16 oC during the first 30 seconds, which gradually reduces to the set temperature (20 oC) within 20 minutes.
? When only magnesium methoxide (100% methoxy content) is treated with the chlorinating medium, the extent of exothermicity is 3 oC to 4 oC after 120 seconds (3 minutes) which gradually reduces to the set temperature (20 oC) within 10 minutes.
? When the magnesium alkoxide having a chemical composition containing 3 wt% of methoxy, 75 wt% ethoxy and 22 wt% Mg is treated with chlorinating medium, the extent of exothermicity is 2 oC to 6 oC after 120 seconds (3 minutes) which gradually reduces to the set temperature (20 oC) within 10 minutes. The extent of exothermicity is less as compared to that of the pure magnesium ethoxide system.
? When the magnesium alkoxide having a chemical composition containing 8 wt % of methoxy, 70 wt% ethoxy and 22 wt% Mg is treated with chlorinating medium, the extent of exothermicity is 1 oC to 2 oC after 120 seconds (3 minutes) which is gradually reduces to the set temperature (20 oC) within 5 minutes. The extent of exothermicity was quite less as compared to that of the pure magnesium ethoxide and pure magnesium methoxide system.
It is found that when the amount of methoxy content is increased from 0.01 to 8 wt% , the extent of exothermicity reduces from 20 oC to 2 oC. Thus, the amount of methoxy content in the magnesium alkoxide composition controls the rate of reaction and thereby the exothermicity. Hence, when the methoxy content is increased (up to 8%) during synthesis of the precursor, low exothermicity with less breakage index of pro-catalyst particle is observed.
In case of pure magnesium methoxide (as catalyst precursor), the extent of heat of reaction is found to be quite less (3 oC to 4 oC) as compared to pure magnesium ethoxide (12 oC to 16 oC).
Further, it is also observed that exothermicity is only 1 oC to 2 oC in the case of magnesium alkoxide containing 8 wt% methoxy in its composition, during the reaction with the chlorinating medium.
The exothermicity of the reaction between magnesium alkoxide and chlorinating medium is controlled to get the desired morphology of the pro-catalyst.
The optimized amount of methoxy content helps to retain the morphology of the pro-catalyst particle during its synthesis and also helps to get morphologically controlled polyolefin resin with reduction in generation of fines during the polymerization reaction, as illustrated in Table-4 and Figures 5 to 8.
The present disclosure is further illustrated herein below with the help of the following examples. The experiments 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 embodiments herein. 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. These laboratory scale experiments can be scaled up to industrial/commercial scale.

Experimental details:
Example 1 and 2 below describe a process for the preparation of a pro-catalyst that can be used in the polymerization of olefins in accordance with the present disclosure and Example 3 below describes the study of reactivity and exothermicity of the reaction in accordance with the present disclosure.
Example 1: Preparation of the catalyst pre-cursor
Batch no. 1 was prepared by adding magnesium powder (55 kg) having a mean particle size of 250 microns to ethanol (1250 L) in the presence of iodine as initiator (1500 gm) at 40 °C with continued stirring at a speed of 350 rpm. Methanol was not used in Batch no.1.
Batch no. 2 was prepared by adding magnesium powder (55 kg) having a mean particle size of 250 microns to a mixture of ethanol and methanol (1250 L) in the presence of iodine as initiator (1500 gm) at 40 °C with continued stirring at a speed of 350 rpm. The reaction was conducted in a step-wise manner due to reaction exothermicity and external temperature control. In the first temperature range, the reaction mixture was heated at a temperature ranging from 40 °C to 60 °C for a period of 1 hour and then in the range of 60 °C to 80 °C (second temperature range) for a period of 2 hours, further the reaction temperature was maintained at 80 °C (third temperature range) for a period of 7 hours.
The vapors of the mixture produced during the reaction were condensed in an overhead condenser. The hydrogen gas produced during the reaction was vented off and the mixture of alcohols left after the reaction was removed by filtration. The filtrate was reused for the synthesis of the pro-catalyst. A wet cake was obtained after removal of the filtrate. The wet cake was dried to obtain (250-260 kg) of magnesium alkoxide (catalyst precursor) in the form of white free flowing spheroidal particles having a bulk density of 0.50-0.55 g/cc and surface area of 10 m2/g.
The precursor was prepared in two batches as given in Table 1. In the first batch, the precursor was formed by magnesium ethoxide only and in the second batch, the precursor was formed by using a mixture of magnesium ethoxide and magnesium methoxide.

Table-1: Chemical composition and particle size distribution of Precursor
Batch No Mg Content
(wt%) Free ethanol
(wt%) Ethoxy content
(wt%) Methoxy content
(wt%) Mean particle size distribution
(PSD) (micron)
1 22 0.3 75 0 27
2 22 0.3 69 8 26

Example 2: Preparation of the pro-catalyst:
A process for the synthesis of the pro-catalyst using the above catalyst precursor is given below.
50 Kg of magnesium alkoxide (catalyst precursor) synthesized in example 1 was treated with an equal volume mixture of 1150 liters of TiCl4 and chlorobenzene in a three step treatment at 100 °C.
In first step of treatment, equal volume mixture of TiCl4 and chlorobenzene (1150 liters) was added to 50 kg of magnesium alkoxide at 20 °C temperature. 22.5 liters of di-isobutyl phthalate was also added immediately when the reaction temperature reached to 40 °C. The reaction temperature was increased to 100 °C and was maintained for 60 minutes under constant stirring.
In second step of treatment, the mixture obtained in first step was filtered and mother liquor was removed. The obtained solid was further reacted with a mixture of TiCl4 and chlorobenzene as described in the previous step, except the reaction time was reduced to 30 minutes. The reaction mixture was filtered and the solid was separated.
In the third step of treatment, the solid obtained in the second step was again treated with the mixture of TiCl4 and Chlorobenzene as described in above step. Further, 5.5 liter of benzoylchloride was added in the reaction mixture and the reaction was allowed to proceed for 30 minutes at 100°C under constant stirring. After 30 minutes, the reaction mixture was cooled to 30 oC and the so obtained reaction mixture was filtered to get solid which was separated by filtration.
During the reaction of magnesium alkoxide with TiCl4, titanium chloroalkoxy compounds were formed which remained on the surface of the solid particles and need to be converted into useful compounds like TiCl4 and ethyl benzoate. Benzoyl chloride was added to recover useful compounds like TiCl4 and ethyl benzoate.
After the three-stage treatment, the solid pro-catalyst was filtered and washed four times with 1000 liters isopentane each, and then it was dried at 50 °C under a stream of nitrogen. Isopentane was used as a washing medium for the solid pro-catalyst formed after the reaction to remove the unreacted TiCl4, chlorobenzene and other byproducts.
55 kg of brown colored pro-catalyst was obtained which was collected in mineral oil by maintaining 30 % (by wt) slurry concentration.
Batch no.1 and 2 (Table-2) of the pro-catalyst were synthesized using precursor batch no.1 (Table-1) while the pro-catalyst batch no.3 and 4 (Table 2) were synthesized from the precursor batch no.2 (Table 1). The chemical composition for various batches as per the above process is shown in Table-2.
Table-2: Chemical composition and particle size of Pro-catalyst
Batch No. Titanium as Ti %wt Magnesium as Mg %wt Ethoxy as Ethanol %wt Chloride as Cl %wt DIBP %wt Solvent n-Hexane
%wt Mean µm Breakage Index*
1 3.1 18.1 0.16 59 18 1.6 21 1.3
2 3.2 17.9 0.14 60 13 5.8 23 1.2
3 2.9 18.5 0.16 59.2 13 6.2 25 1
4 3 18.7 0.17 58.9 9.3 9.9 26 1
* The particle breakage index is defined as the ratio of mean particle size of precursor to mean particle size of pro-catalyst.

From the table 2, it is observed that the particle breakage index is comparatively higher in Batch 1 and 2 than the particle breakage index of Batch 3 and 4.
The catalyst composition in Batch 1 and 2 were synthesized from the precursor which does not contain any methoxy content in its composition. The particle breakage index is close to 1 in Batch 3 and 4, when around 8 wt% of methoxy content was incorporated in the precursor. This may be due to controlled reactivity towards titanium tetrachloride or increased particle strength of the precursor due to incorporation of the methoxy content.

Example 3: Determination of the reactivity of the pro-catalyst and Exothermicity:
Magnesium alkoxide (catalyst precursor) containing different amounts of methoxy content was studied for its reactivity towards the chlorinating medium (equal volume mixture of TiCl4 and Chlorobenzene). The compositions are given in Table 3.
The reactivity towards the chlorinating medium was determined by measuring the rise in the reaction temperature with respect to the set temperature over a period of time, i.e. exothermicity of the reaction or the extent of heat of reaction (Delta oC), as depicted in Figures 1 to 4.
The extent of the heat of the reaction (exothermicity) was measured by taking the difference between the temperature of the reaction and the jacket vessel.
The study was carried out by maintaining the temperature of 20 oC for 60 min with continuous stirring of the catalyst precursor and chlorinating solvent by a mechanical stirrer. The unreacted titanium tetrachloride, which remained after the reaction was removed by washing 3 times (100ml x 3 time) with n-hexane at the same temperature. The stirring was carried out for 15 minutes followed by 15 minutes residue settling.
The measured exothermicity in various experiments is given below:-
a) Reaction between pure magnesium ethoxide and titanium fluid medium (System 1):
The extent of exothermicity was monitored for the reaction temperature and reaction time between magnesium ethoxide and titanium tetrachloride as well as with the chlorinating medium (TiCl4 +chlorobenzene) as shown in Figure 1.
In Figure 1, Delta °C (A) is the difference between the temperature of set point and the reaction mixture (pure magnesium ethoxide having 0% methoxy content with TiCl4) and
Delta °C (BR) is the difference between the temperature of set point and the reaction mixture (pure magnesium ethoxide having 0 wt% methoxy content with TiCl4 + Cl-Benzene).
From Figure 1, it is observed that the extent of exothermicity was 12 oC to 16 oC during the first 30 seconds, which is gradually reduced to the set of temperature 20 oC within 20 minutes.
Figure 5 represents the normal SEM image and zoomed SEM image of the catalyst precursor, the pro-catalyst and the polymer. ‘A’ represents the normal image of pure magnesium ethoxide while ‘A1’ represents the zoomed image of pure magnesium ethoxide. Similarly ‘B’ represents procatalyst and ‘B1’ represents the zoomed image. ‘C’ represents polymer and ‘C1’ represents zoomed image of the polymer

b) Reaction between pure magnesium methoxide and titanium fluid medium (System 2): The magnesium methoxide is found to be less exothermic when it is reacted with titanium tetrachloride as shown in Figure 2.
In Figure 2, Delta °C (K) is the difference between the temperature of set point and the reaction mixture (pure magnesium methoxide having 100% methoxy content with TiCl4) and Delta °C (L) is the difference between the temperature of set point and the reaction mixture (pure magnesium methoxide having 100% methoxy content with TiCl4 + Cl-Benzene).
From Figure 2, it is observed that the extent of exothermicity was 3 oC to 4 oC after 120 seconds (3 min) which was gradually reduced to the set temperature 20 oC within 10 min.
Figure 6 represents the normal SEM image and zoomed SEM image of the catalyst precursor, the pro-catalyst and the polymer. ‘A’ represents the normal image of pure magnesium methoxide while ‘A1’ represents the zoomed image of pure magnesium methoxide. Similarly ‘B’ represents pro-catalyst and ‘B1’ represents zoomed image. ‘C’ represents polymer and ‘C1’ represents zoomed image of polymer

c) Reaction between magnesium alkoxide (with 3% methoxy) and titanium fluid medium (System 3): The reaction between magnesium alkoxide and titanium tetrachloride is shown in Figure 3.
In Figure 3, Delta °C (SR1) depicts the difference between the temperature of set point and the reaction mixture (magnesium alkoxide having 3% methoxy content with TiCl4) and Delta °C (T) depicts the difference between the temperature of set point and the reaction mixture (magnesium alkoxide having 3% methoxy content with TiCl4 + Cl-Benzene).
From Figure 3, it is observed that the extent of exothermicity was 2-6 oC after 120 seconds (3 min) which was gradually reduced to the set temperature 20 oC with 10 minutes. The extent of exothermicity was less as compared to that of the pure magnesium ethoxide system as described in (a-system 1).
Figure 7 represents the normal SEM image and zoomed SEM image of the catalyst precursor, the pro-catalyst and the polymer. ‘A’ represents the normal image of 3% magnesium methoxide while ‘A1’ represents the zoomed SEM image of 3% magnesium methoxide. Similarly ‘B’ represents the pro-catalyst and ‘B1’ represents zoomed image. ‘C’ represents polymer and ‘C1’ represents zoomed image of polymer.

d) Reaction between magnesium alkoxide (with 8% methoxy) and titanium fluid medium (System 4):
The reaction between magnesium alkoxide having 8% methoxy content (by wt) and titanium tetrachloride is shown in Figure 4.
In Figure 4, Delta °C (G) is the difference between the temperature of set point and the reaction mixture (magnesium alkoxide having 8% methoxy content with TiCl4) and Delta °C (HR) is the difference between the temperature of set point and the reaction mixture (magnesium alkoxide having 8% methoxy content with TiCl4 + Cl-Benzene).
From Figure 4, it is observed that the extent of exothermicity was 1 oC to 2 oC after 120 seconds (3 min) which was gradually reduced to the set temperature 20 oC within 5 minutes. The extent of exothermicity was quite less as compared to that of the pure magnesium ethoxide system as described in (a).
Figure 8 represents the normal SEM image and zoomed SEM image of the catalyst precursor, the pro-catalyst and the polymer. ‘A’ represents the normal image of 8% magnesium methoxide while ‘A1’ represents the zoomed image of 8% magnesium methoxide. Similarly ‘B’ represents pro-catalyst and ‘B1’ represents zoomed image. ‘C’ represents polymer and ‘C1’ represents zoomed image of polymer.

Hence, when the amount of methoxy content is increased from 0-8% (by wt), the extent of exothermicity reduces from 20 oC to 2 oC. Thus, the amount of methoxy content controls the rate of the reaction and thereby the exothermicity. Hence, when the methoxy content is increased during the synthesis of magnesium alkoxide, low exothermicity with less breakage of catalyst particle is observed during the catalyst synthesis.

The chemical composition of the above systems 1 to 4 is summarized in the table 3:
Table 3: chemical composition of above systems (1) to (4)
Ti Wt% Mg Wt% Cl Wt% Ethoxy Wt% Methoxy Wt%
System-1 10.0 14.0 66.0 10.0 0.0
System-2 7.4 11.1 31.5 0 50.0
System-3 8.0 18.1 47.2 26.1 0.5
System-4 3.0 18.0 24.0 53.0 2.0

In case of pure magnesium methoxide, the extent of heat of the reaction is quite less (3 oC to 4 oC) as compared to other magnesium alkoxides having higher number of carbon atoms (12 oC to 16 oC).
Further, it was also observed that exothermicity is only 1 oC to 2 °C in the case of magnesium alkoxide containing methoxy as one of the alkoxy in its composition during its reaction with the chlorinating medium.
Example 4: Effect of the amount of methoxy content on the pro-catalyst and the resin morphology:
The morphology of the pro-catalyst particle and the polymer resin was also studied. As shown in Figures 5-8, the study was carried out by taking pure magnesium ethoxide as the catalyst precursor in system 1 (Figure 5), magnesium methoxide as the catalyst precursor in system 2 (Figure 6), magnesium alkoxide where the methoxy content was 3% in system 3 (Figure 7) and magnesium alkoxide where the methoxy content was 8% in system 4 (Figure 8).
When pure magnesium ethoxide (system 1) was used as catalyst precursor for preparing pro-catalyst and further, for polymerizing the olefin, it was observed that the sphericity of particles of the catalyst precursor, the pro-catalyst and the polypropylene resin was very less as compared to the precursor having methoxy content in its composition (system 3 and 4).
In case of pure magnesium methoxide (system 2) as the catalyst precursor, the pro-catalyst and the polypropylene resin material obtained was observed to be lumpy. The particle size could not be measured for the so obtained lumpy material and the sphericity was also observed very less as compared to the remaining three systems (system 1, 3 and 4).
When magnesium alkoxide (system 3 and 4) having methoxy as one of the alkoxy (methoxy content is 3% and 8%) is used for the synthesis of the pro-catalyst and further used for polymerization of olefin, the polymer has shown higher sphericity of particles and good morphology of the pro-catalyst as well as polypropylene resin.
The results are given in the Table 4 below.

Table 4: Effect of the amount of methoxy content on the pro-catalyst and the resin morphology:
Precursor Precursor Properties Pro-catalyst Properties PP Resin Properties
Sphericity PSD in µm Spericity PSD in µm Spericity PSD in µm
D10 D50 D90 Mean D10 D50 D90 Mean D10 D50 D90 Mean
System-1
(Pure magnesium ethoxide) 0.82 12 25 38 26 0.68 8 21 30 22 0.72 220 368 485 364
System-2
(Pure magnesium methoxide) 0.35 Lumpy Materials 0.55 5 18 45 19 0.44 102 215 448 220
System-3
(3% wt Methoxy) 0.86 14 23 35 23 0.75 8 25 48 24 0.79 225 351 490 345
System-4
(8% wt methoxy) 0.93 16 25 39 27 0.85 13 24 36 24 0.82 253 352 408 351
*D10, D50 and D90 – Particle size distribution (diameter) of 10% , 50% and 90% particles.
*Sphericity is also called as circularity of particles and is determined by scanning electron microscopy.
The process for preparing the catalyst of the present disclosure has comparatively low exothermicity.
The exothermicity of the catalyst of the present disclosure is inversely proportional to the amount of methoxy content inserted in the catalyst precursor and is directly proportional to the chain length of alcohol used.
Low exothermicity of the catalyst of the present disclosure is controlled by incorporation of methoxy content.
Technical advances
? A process for preparing a pro-catalyst that can be used to prepare polyolefin resin with controlled morphology.
? A process for preparing a pro-catalyst that has low exothermicity of the reaction.
? A process for preparing a pro-catalyst from a catalyst precursor that has an optimum amount of methoxy content for controlling the morphology of the pro-catalyst.
? A process for preparing a pro-catalyst that produces comparatively lesser amount of fines during polymerization.

The exemplary embodiments herein quantifies the benefits arising out of this disclosure and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the 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 foregoing 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.
Any discussion of documents, acts, materials, devices, articles and 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.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications 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 modifications in the nature of the disclosure or the preferred embodiments 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.