FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10; rule 13) Precursor For Polyolefin Catalyst RELIANCE INDUSTRIES LTD. An Indian Company of 3rd Floor, Maker Chamber-IV, 222, Nariman Point, Mumbai 400 021, Maharashtra, India. Maharashtra, India. Inventors Makwana Umesh Kothari Ajay Desai Bhavesh Gupta Virendrakumar THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. Filed of Invention The present invention relates to a process for preparation of a precursor for a catalyst. More particularly the present invention relates a process for preparation of a magnesium based precursor for a polyolefin catalyst. Background The commercially available magnesium alkoxides are synthesized by the reaction of magnesium metal with alcohols in the presence of reaction initiators like iodine. For example, WO2005/044873 discloses a method for synthesizing spherical magnesium alkoxide particles by reacting magnesium with an alcohol mixture at a temperature below the boiling point of the mixture using I2 as a reaction initiator. There are several drawbacks associated with the method as provided in the aforesaid PCT application. The spherical magnesium alkoxide particles synthesized by such method are frangible and they do not retain their morphology or particle size during the synthesis of Ziegler Natta procatalyst, especially when the procatalyst synthesis is carried out on a plant scale. Furthermore, a resin produced using the method reported in WO2005/044873 exhibits low resin bulk density which in turn hampers the plant throughput. A method which attempts to overcome the problems mentioned above has been disclosed in US5077357. It employs dissolution and re-precipitation methodology to incorporate chlorine and the titanium atoms in the matrix of the precursor. In accordance with the method disclosed by US5077357, magnesium alkoxide is dissolved in a halo-hydrocarbon solvent by heating a mixture of magnesium alkoxide, titanium tetra chloride, titanium tetra ethoxide, alcohol, and a phenol derivative at an elevated temperature and the re-precipitation is carried out by the removal of alcohol from the system. The solid semi spherical particles magnesium particles are separated by filtration. Provided herein below is a brief summary of the known processes wherein iodine has been used as an initiator in the synthesis of the magnesium alkoxide based precursor. A method for producing the morphology controlled magnesium alkoxide with high mechanical strength and controlled particles size precursor which employs iodine is disclosed in WO2009/130707. It involves the activation of the magnesium metals by iodine to react with a mixture of alcohols at a controlled rate. A method for synthesis which employs magnesium alkoxide as a carrier material for preparing Ziegler Natta Catalysts with Spherical Morphology has been disclosed in Macromol. React Eng., 2(2008)233-239. It employs Metal halides (MnC12, FeCI2, CoC12 and ZnC12) to synthesize Magnesium ethoxide in the presence of iodine. Another article, Applied Catalysis A: General 350(2008) 197-206 "Particle growth of magnesium alkoxide as a carrier material for polypropylene polymerization catalyst" provides the details of a process that employs Iodine as a reaction initiator. This article also provides the details of the mechanism by which particles are formed (agglomerates of primary particles) on the surface of magnesium metal. Also, disclosed in this article is the replication of morphology from precursor to catalyst to polymer. Apart from the abovementioned references, methods for synthesis of the magnesium alkoxide precursor using halogen initiators and activators are taught in US 2009/0112027, US2009/0233793, US2009/0148702, US5077357 and WO/2009/130707. The drawback of the precursor prepared through the iodine activator is that its particle strength is low and therefore it is prone to breakage. This results in the formation of fines during catalyst synthesis. As a result a polymer obtained through the catalyst also contains very high level of fines which causes frequent choking problems in a commercial plant. Furthermore, the precursor prepared through iodine activator form iodine compounds which remain with the precursor. This adversely affects the performance of the catalyst. In view of the above, there is therefore exists a need for a method to synthesize a magnesium alkoxide based precursor with high particle strength that overcomes the drawbacks associated with the prior art. OBJECTS An object of the invention is to provide a method for preparation of a morphologically controlled catalyst precursor with high particle strength. Another object of the invention is to provide a method that improves the precursor strength without contaminating the alkoxide matrix of the precursor. Still another object of this invention is to provide an energy efficient method for preparation of the precursor. A further object of the invention is to prepare a precursor in an energy efficient manner. A still further object of the present invention is to provide a supported Ziegler-Natta catalyst with controlled morphology with improved particle strength. Summary: In accordance with the present invention there is provided a method for synthesis of a catalyst precursor with controlled morphology; said method comprising the following steps: - reacting predetermined amount of magnesium metal particles with an alcohol at a temperature ranging between 35 °C to 50 °C under agitation to obtain a reaction mixture; - adding predetermined amount of titanium tetrachloride to the reaction mixture leading to the evolution of hydrogen from the reaction mixture; - heating the reaction mixture gradually till the temperature of the mixture reaches to a reflux temperature and refluxing the reaction mixture till the time the evolution of hydrogen from the mixture stops completely; - increasing the temperature of the reaction mixture to about 100°C to remove the excess alcohol in the reaction mixture to obtain a precursor and subjecting the same to drying. Typically, the alcohol is selected from the group consisting of C1-C12 aliphatic alcohols and any mixture thereof. Preferably, the alcohol is selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol and any mixture thereof. Typically, the proportion of the metal, the alcohol and titanium tetrachloride, when expressed in terms of moles, is in the range between 0.5:2:0.001 to 1:6: 0.15. In accordance with a preferred embodiment of the present invention, the proportion of the metal, the alcohol and titanium tetrachloride, when expressed in terms of moles is 1:5: 0.03. In one embodiment, the method of the present invention further comprises preparing a supported Ziegler-Natta catalyst from the precursor; wherein preparing the catalyst comprises reacting the precursor with titanium tetrachloride optionally in the presence of an electron donating species to the obtain a catalyst, treating the catalyst with a titanium halide again and washing the same with a hydrocarbon solvent to remove the free titanium. In accordance with one embodiment of the present invention, the electron donating species is ethyl benzoate and the catalyst prepared is a mono-ester catalyst. In accordance with another embodiment of the present invention, the electron donating species is di iso butyl phthalate and the catalyst prepared is a di-ester catalyst. Typically, the hydrocarbon solvent is selected from the group consisting of aromatic or aliphatic hydrocarbons and any mixture thereof. Preferably, the hydrocarbon solvent is preferably selected from the group consisting of chlorobenzene, toluene, ortho-chloro toluene, C1-C14 aliphatic hydrocarbon and any mixture thereof. Typically, the reaction mixture containing the precursor, titanium halide and an electron donating species is heated up to 100°C within 15 minutes and the temperature is kept constant for about 30 minutes. In another aspect of the present invention there is provided a supported Ziegler-Natta catalyst with controlled morphology that is essentially devoid of iodine. Typically, sphericity value of the catalyst is in the range of 0.80 to 0.90. Typically, the particle breakage index of the catalyst is in the range of 0.85 to 0.97. DETAILED DESCRIPTION The morphology of the precursors is a function of process parameters like the rate of reaction, temperature and the types of alcohols used. The morphology of final polyolefin is a replication of catalyst and the catalyst morphology is replication of precursor morphology. The present invention therefore provides a method for preparation of a precursor with desired morphology and high particle strength that does not involve contamination by iodine. The method in accordance with the present invention overcomes the drawbacks associated with the prior art process by employing TiCI4 as a magnesium metal activator. This increases the strength of the particles and avoids the contamination of the catalyst. Furthermore, the residue of titanium in the precursor does not affect the performance of the catalyst as it is one of the catalyst components of the catalyst system. In accordance with the method for preparation of a precursor with controlled morphology in accordance with the present invention a predetermined quantity of magnesium metal is introduced to an alcohol. Alcohol that is used in accordance with the method of the present invention is selected from the group consisting of C1-C12 aliphatic alcohols and any mixture thereof. Preferably, the alcohol is selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol and mixture thereof. The addition of magnesium particles to the alcohol is carried out gradually under agitation at a temperature ranging between 35°C to 50 °C. Preferably, the magnesium metal particles are added to the alcohol at a temperature of about 40 °C under continuous agitation. The agitator speed is maintained in range of about 150 rpm to about 400 rpm. Preferably, the speed of the agitator is maintained at 300 rpm. After about 20 minutes, pre-determined amount of titanium tetrachloride is added to the reaction mixture. The introduction of titanium tetrachloride, which acts as an initiator; results in evolution of hydrogen from the reaction mixture. The evolution of hydrogen indicates the commencement of the reaction. The rate of the reaction is monitored by observing the rate of evolution of the hydrogen from the reaction mixture. The proportion of the reactants (when expressed in terms of moles), magnesium metal, ethanol and titanium tetrachloride typically ranges between 0.5:2:0.001 to 1:6: 0.15. Preferably, the proportion of the metal, alcohol and titanium terra chloride is 1:5:0.03. The temperature of the reaction mixture is increased in a stepwise manner. The temperature is increased only when the effervescence of hydrogen stops indicating the stoppage of the reaction. The temperature of the reaction mixture is increased in a stepwise manner till the reflux temperature of the reaction mixture. Typically, the reflux temperature of the mixture ranges between 70°C to about 90°C, preferably about 80°C. The time period for reaching the reflux temperature is typically ranges between 3.5 to about 4 hours. After the temperature of the mixture reaches to its reflux temperature, the reaction mixture is refluxed for a period ranging between 40 minutes to 120 minutes. In accordance with one embodiment of the invention, the reflux temperature is 80°C and the time period for which the reaction mixture is refluxed is 60 minutes. Once the hydrogen evolution is stopped at the reflux temperature of the reaction mixture, the temperature of the reaction mixture is increased to about 100°C. The excess of alcohol is evaporated. Alternatively, the excess of ethanol is condensed under Nitrogen atmosphere. The solid precursor is subjected to drying at a temperature of about 60 °C to about 130 °C under the flow of nitrogen till to obtain a free flowing powder. The final product is collected and weighed and the chemical composition is determined. In another aspect, the present invention also provides a process for preparation of monoester and diester catalysts using the precursor in accordance with the present invention. The method for synthesis of supported Ziegler-Natta (ZN) catalyst for propylene polymerization from titanium based magnesium alkoxide precursor prepared in accordance with the method of this invention comprises reacting titanium based precursor with a mixture of titanium halide and halogenated aromatic solvent optionally in the presence of electron donating species. Typically, the electron donating species are selected from the group consisting of monoester and diester aromatic moieties. Preferable the electron donating species is at least one selected from the group consisting of ethyl benzoate and di iso butyl phthalate. Typically, the reaction is carried out between 80°C to 110°C for a time period ranging between one to two hours. The catalyst obtained is again treated with titanium halide and washed with hydrocarbon solvent until all the free titanium is removed. Typically, the hydrocarbon solvent is selected from the group consisting of aromatic or aliphatic hydrocarbons and mixture thereof. Preferably, the hydrocarbon solvent is selected from the group consisting of chlorobenzene, toluene, ortho-chloro toluene, C1-C14 aliphatic hydrocarbon and any mixture thereof. In still another aspect of the present invention, there is a provided a supported Ziegler-Natta catalyst with controlled morphology that is essentially devoid of iodine prepared in accordance with the method as described herein above. Typically, the sphericity value of supported Ziegler-Natta catalyst with controlled morphology prepared in accordance with the present invention is in the range of 0.80 to 0.90. Typically, the particle breakage index of the catalyst prepared in accordance with the present invention is in the range of 0.85 to 0.97. The catalyst produced in accordance with the method of the present invention is used for olefin polymerization to produce regular shaped polymer particles. In still another aspect of the present invention there is provided a method for synthesis of supported Ziegler-Natta (ZN) catalyst for olefin polymerization from the titanium based magnesium alkoxide precursor of the present invention. The method for preparation of the olefin catalyst using the precursor of the present invention comprises reacting the precursor with a mixture of titanium halide and a halogenated aromatic solvent. Typically, the reaction is carried out between 80°C to 110°C for a time period ranging between one to two hours. The catalyst obtained is again treated with titanium halide and washed with hydrocarbon solvent until all the free titanium is removed. Typically, the hydrocarbon solvent is selected from the group consisting of aromatic or aliphatic hydrocarbons and mixture thereof. Preferably, the hydrocarbon solvent is selected from the group consisting of chlorobenzene, toluene, ortho-chloro toluene, C1-C14 aliphatic hydrocarbon and any mixture thereof. The invention will now be described with the help of following non-limiting examples; Example 1 Synthesis of a titanium tetrachloride based magnesium alkoxide precursor in accordance with the present invention: In a three necked reactor 150 ml of alcohol (ethanol) was taken. 10 gm of Mg metals were added at elevated (40°C). The speed of the agitator was maintained at 300 rpm. Table 1 provided herein below provides the particle size distribution of the magnesium particles. Table -1 : Particle size of Magnesium Metal used Mesh No. Micron Size TareWt. Gross Wt. Net Wt. % Retention gm gm gm on 40 400 0.7313 0.7338 0.0025 0.12 60 250 0.724 1.5385 0.8145 40.59 80 177 0.6739 1.5099 0.836 41.66 100 149 0.6668 0.8434 0.1766 8.8 140 105 0.5276 0.6537 0.1261 6.28 200 74 0.5023 0.5511 0.0488 2.43 PAN PAN 0.8347 0.8369 0.0022 0.11 2.0067 ACTUAL Wt. = 99.98 100 <140u = 2.54 APS 252 After 20 minutes a calculated quantity of Titanium tetrachloride was added to it and immediately the evolution of H2 with very high effervesces was observed which indicated the start of the reaction. The exact process parameters are shown in the following Table-2. Table-2: Process Parameters Experiment Mg TiCU Ethanol Temp. Total RPM Moles Moles Moles Detail metals Qty Qty <°C) Time of Mg of of Qty (gm) (ml) (ml) From -To