FORM-2
THE PATENT ACT, 1970
(39 OF 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; Rule 13)
TITANIUM DIOXIDE AND PROCESS FOR ITS SYNTHESIS
RELIANCE INDUSTRIES LIMITED
an Indian Company
of Reliance Technology Group, Reliance Corporate Park
7B Ground Floor, Thane-Belapur Road
Ghansoli, Navi Mumbai-400 701.
Maharashtra, India
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF THE INVENTION
The present invention relates to a method for preparing nano crystalline Titanium
dioxide.
Particularly, the present invention relates to a method for preparing nano
crystalline Titanium dioxide from titanium containing catalyst waste residue.
BACKGROUND OF THE INVENTION
Ziegler-Natta catalysts are used in the synthesis of polymers mainly vinyl polymers. Ziegler catalysts have remarkable property of polymerizing a wide variety of monomers to linear and steroregular polymers. Ziegler-Natta catalyst is a special type of co-ordination catalyst in which two components are present and referred as catalyst and co-catalyst. The catalyst component consists of halides of IV-VIII group elements having a transition valance and the co-catalyst is organometallic compound such as alkyls, aryls and hydrides of group I-IV metals.
During the commercial synthesis of Ziegler-Natta catalysts, solvents namely TiC14, and other aliphatic and aromatic solvents are used. The solvents are recovered regularly to maintain the purity of the system and to remove undesired chemical species. The distillation process results in heavy solvent residue generation consisting of a complex mixture of organic, organo-metallic and inorganic chemical species. The solvent residue is characterized by the presence of titanium, in the form of TiClx(OC2H5)4-x, with x ranging from 0 to 4, TiOCl2 and other titanium containing organo- metallic or inorganic components.
EXISTING KNOWLEDGE
EP2067747A1 discloses a method for producing a porous titanium oxide. The porous titanium oxide is obtained by adding an alkali into a titanium salt solution containing a polyhydric alcohol, heating and hydrolyzing the resulting mixture.

EP1990315A1 provides a process for preparing nanocrystalline titanium dioxide which comprises precipitating a mixture comprising hydrated titanium oxide and a separable filtering agent (which is prepared by reacting titanium tetrachloride or titanium oxychloride with MOH wherein M is selected from the group consisting of NH4, Group 1 metals and mixtures thereof in the presence of a solvent). It particularly, discloses use of pure TiCl4 or TiOCl2 as raw material which are treated with water, alcohol and alkali to prepare a cake.
GB456544A disclose a process of producing titanium dioxide which comprises adding an acid solution of a titanium salt at a temperature below its boiling point to water containing a polysacoharide at an elevated temperature below the boiling point thereof, and then after hydrolysis boiling the mixture until the polysaccharide is converted into sugar.
GB 1023275 discloses a process for the production of titanium dioxide which comprising forming an aqueous solution of titanium tetrachloride; thermally hydrolysing this aqueous titanium tetrachloride solution and thereafter separating the titanium dioxide and aqueous hydrochloric acid thus produced; mixing the aqueous hydrochloric acid thus formed and titanium tetrachloride in such proportions and at such a temperature as to form gaseous hydrogen chloride and a thermally hydrolyzable aqueous titanium tetrachloride solution and recovering the gaseous hydrogen chloride and thermally hydrolysing the aqueous titanium tetrachloride solution to form titanium dioxide.
EP2052036 discloses a process for manufacturing a titanium dioxide pigment which comprises the steps of preparing an aqueous, high solids slurry by gathering materials including crude titanium dioxide from the oxidation of titanium tetrachloride, a dispersant and water and then mixing the gathered materials to

form the slurry; diluting the aqueous, high solids slurry by adding a further amount of water to the high solids slurry with mixing; media-milling the resultant aqueous, lesser solids slurry: recovering the media-milled, crude titanium dioxide product; and finishing the media-milled, crude titanium dioxide product to produce a finished titanium dioxide pigment product.
US5468463 discloses a process for the preparation of pure titanium dioxide which consisting essentially of reacting titanium tetrachloride with sulphuric acid to form a titanyl sulphate solution, separating the resulting hydrogen chloride, concentrating the solution and then adding sulphuric acid to adjust the weight ratio of sulphuric acid to titanium dioxide to between 1.7 and 2.0 and adjusting the titanium dioxide concentration to between 250 and 300 g/1, hydrolyzing the solution to form a precipitate of titanium dioxide hydrate, filtering off the resulting titanium dioxide hydrate precipitate, and then calcining the precipitate to form titanium dioxide in the rutile or anatase form.
US3560234 discloses a process for the manufacture of pigments of titanium dioxide in the rutile form. It discloses use of pure Ti(S04)2 for the preparation of titanium dioxide.
The processes disclosed in the aforementioned documents involve preparation of titanium oxide from pure Ti salt with or without alkali.
EP418632 discloses a process for producing titanium dioxide by digestion of titanium-containing raw materials with sulphuric acid, hydrolysis of the titanyl sulphate thus formed, separation of the metal sulphate-containing sulphuric acid from the titanium dioxide hydrate formed in the hydrolysis, bleaching of the titanium oxide hydrate by reductive treatment in the presence of sulphuric acid, calcination of the bleached titanium oxide hydrate to give titanium dioxide,

separation of dust and H2S04 from the calcination gases and desulphurisation of the S02-containing waste gases to form 2 to 20% by weight sulphuric acid. It particularly disclose use of Ti(S04)2 for the preparation of titanium dioxide.
US5277816 discloses a process for producing titanium dioxide which discharges no waste is disclosed. In a first step, a sulfuric acid solution containing titanium ion with one or more kinds of metal ions is contacted with a first organic solvent to extract the titanium ion as a sulfuric acid complex. The organic solvent containing the extracted titanium as a sulfuric acid complex (titanyl sulfate) is contacted with an aqueous liquid to strip the titanium into the aqueous liquid and regenerate the first organic solvent. In a second step, the aqueous liquid containing the titanium is subjected to hydrolysis to form insoluble titanium hydroxide, and the titanium hydroxide is washed with dilute sulfuric acid and/or clear water. In a third step, the raffinate of extraction in the first step is contacted with a second organic solvent to extract the titanium ion and the organic solvent containing extracted titanium is contacted with water, dilute sulfuric acid solution or a dilute titanyl sulfate solution to strip the titanium, and regenerate the organic solvent.
US4098869 discloses hydrolysis of a titanyl sulphate solution which is carried out according to the autonucleation method of gradually adding the solution to a body of water at a substantially constant rate over 10-20 minutes, in such a way as to obtain an ionic concentration after one minute of feeding of from 75 to 105 g/1. the concentration of sulphuric acid in the final hydrolysis solution being regulated to a value of from 310 to 330 g/1 by adding water from the commencement of clouding of the hydrolysis solution up to the end of hydrolysis.
GB308725 discloses a process of hydrolytic precipitation of titanium compounds from mineral acid titaniferous solutions, wherein the titaniferous solution is added to a hot aqueous bath so as to effect hydrolysis of the solution and consequent

precipitation of the titanium compounds, characterized by effecting the hydrolysis in the presence of 70 a small proportion of organic acid dissolved in the hydrolysis liquor.
EP457120 discloses a process for the preparation of titanium dioxide by the sulphate process by digestion of titanium raw materials using a mixture of fresh and recirculated sulphuric acid, hydrolysis of the titanyl sulphate formed with the formation of hydrated titanium oxide and dilute acid, calcining of the hydrated titanium oxide to give titanium dioxide and recovery of the sulphuric acid from the dilute acid by concentration by evaporation and removal of the solid metal sulphates.
EP654539 discloses a process for preparing titanium dioxide by the sulphate process, in which titanium-containing raw materials are digested in the presence of metallic iron and sulphuric acid, subsequently hydrolysed and the titanium oxide hydrate (hydrated titanium oxide) formed is calcined.
US7462337 discloses a method of recovering titanium dioxide from a titanium oxide bearing raw material, such as e.g. steel slags rich in Ti02 includes the steps of grinding the titanium dioxide raw material, reacting the particulate raw feed material with sulphuric acid under specified conditions, digesting and filtering the resultant cake material containing titanyl sulphate, hydrolysing the titanyl sulphate and, after washing the hydrolysate, calcining the hydrolysate to produce titanium dioxide. US7462337 is silent as far as preparation of Ti02 from catalyst residue and conversion to nano crystalline Ti02.
EP356132 discloses a method for manufacturing titanium oxide, comprising bringing a sulfuric acid solution containing predominantly titanium ion together with one or more kinds of metal ions into contact with an organic solvent

containing one or more species selected from oxygen-containing organic solvents, alkyl amines and alkyl aryl amines to extract the titanium ions in the form of a sulfuric acid complex from the sulfuric acid solution, and bringing the organic solvent containing the extracted titanium into contact with water or a dilute aqeous sulfuric acid solution inversely to extract the titanium from the organic solvent into the water or the dilute sulfuric acid solution and to regenerate the organic solvent.
EP343418 discloses a process for the preparation of titanium dioxide by digestion of titanium-containing raw materials with sulphuric acid, hydrolysis of the titanylsulphate thus formed, separation of the metal sulphate-containing sulphuric acid from the hydrated titanium dioxide formed in the hydrolysis, bleaching of the hydrated titanium oxide by a reductive treatment in the presence of sulphuric acid, calcination of the bleached hydrated titanium oxide to titanium dioxide and desulphurisation of the S02-containing waste gases from the process on moist activated carbon to form 5 to 20% sulphuric acid.
US5030439 discloses a method for the preparation of particulate pigmentary titanium dioxide. The method comprises reacting in solution, a precursor titanium tetrahalide with sulfuric acid to produce an intermediate titanyl sulfate product. Following crystallization and recovery of this intermediate product from solution the crystallized intermediate is redissolved in an aqueous solvent medium and hydrolyzed at elevated temperatures to provide a particulate amorphous titanium dioxide intermediate product. After separation from the aqueous solvent medium, this intermediate product then is subjected to calcination at elevated temperatures to produce the desired particulate titanium dioxide end product.
US20080003152 discloses a process for preparing Ti02 powders starting from a liquid comprising chlorinated titanium compounds. The process comprising: a)

atomizing said liquid, thereby forming an atomized liquid and reacting the atomized liquid with a flow of steam and air at a temperature of 100-250degree C. to convert said chlorinated titanium compounds to titanium dioxide powder. thereby forming a gaseous phase; b) feeding the gaseous phase and the entrained Ti02 powder obtained from step a) to an oven comprising an inlet and a top portion, operated at a temperature in the range 400-900degree C. to remove residual organic compounds and hydrochloric acid from said powders. The particle size distribution of the powder is 5-10 micron.
None of the prior art documents disclose direct preparation of rutile phase nano crystalline Ti02 from titanium containing catalyst waste residue.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a method for preparing Nano-crystalline Titanium dioxide from a catalyst waste residue.
Another object of the invention is to prepare Nano crystalline Titanium dioxide directly in rutile phase.
Still another object of the invention is to prepare Nano crystalline Titanium dioxide in rutile phase at low temperature.
A further object of the invention is to purify Titanium dioxide recovered from the catalyst residue by removing other metal, organic and organometallic impurities.
Still further object of the invention is to prepare Nano crystalline Titanium dioxide for application as colored pigments and as UV protection media.

Yet another object of the invention is to prepare nano-crystalline Ti02 for photo-catalytic applications.
Yet another object of the invention is to prepare nano-sized Ti02 through ball milling for obtaining particle size in the desired range based on the application.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a method of preparing Nano crystalline Titanium dioxide particles from Titanium bearing waste residue obtained from the process of manufacturing Ziegler-Natta catalysts; said method of preparing the Titanium dioxide Nano crystalline particles comprising the following steps:-
i. hydrolyzing a waste residue in a media selected from the group of media consisting of de-mineralized water, mineral acid and alcohol to obtain a hydrolyzed mixture;
ii. aging the hydrolyzed mixture to obtain an aged hydrolyzed mixture; iii. subjecting the aged hydrolyzed mixture to decantation and filtration to separate a solid component mixture from liquid;
iv. washing the solid component mixture with a first washing media to remove at least undesired metal salts:
v. washing the solid component mixture with a second washing media to remove at least organic components; and
vi. drying the washed solid component mixture to obtain nano crystalline titanium dioxide with crystallite size 2-l00nm and titanium dioxide nano crystalline particles of size ranging from 1 to 25μ m.

Typically, the media consist of 20% to 100% of de-mineralized water, 0 to 20% of mineral acid and 0 to 80% of alcohol.
Preferably, the media consist of 60 % to 100 % of de-mineralized water, 0 to 5 % of mineral acid and 0 to 40 % of alcohol.
Typically, the mineral acid is at least one acid selected from the group consisting of hydrochloric acid, sulphuric acid and nitric acid.
Typically, the alcohol is at least one alcohol selected from the group consisting of aliphatic alcohols which include methanol, ethanol and propanol.
Typically, the aging of the hydrolyzed mixture is carried out for a period of about 1 to about 10 days.
Typically, the first washing media is a mixture of de-mineralized water and dilute mineral acid selected from the group of acids consisting of hydrochloric acid, sulphuric acid and nitric acid.
Typically, the second washing media is at least one hydrocarbon selected from the group of hydrocarbons consisting of hydrocarbon solvents which include isopentane, pentane and heptane.
In accordance with another embodiment of the present invention the method of preparing the Titanium dioxide Nano crystalline particles includes a further step of washing the washed solid component mixture with a low boiling organic solvent.

Typically, the low boiling organic solvent is at least one selected from the group consisting of alcohols, polar solvents and other solvents capable of removing organic impurities.
Typically, the alcohol is at least one selected from the group consisting of methanol, ethanol, propanol and the like.
Typically, the polar solvent is at least one selected from the group consisting of tetrahydrofuran, acetone, dimethyl ether, diethyl ether and the like.
Typically, the method of preparing the Titanium dioxide Nano crystalline particles includes the washing effected at a temperature ranging from room temperature to the refluxing temperature of the washing media.
Typically, the waste residue is hydrolyzed in relatively low concentrations wherein the ratio of waste residue to hydrolyzing media ranges between 0.001: 1 and 1: I.
In accordance with another embodiment of the present invention the method of preparing Titanium dioxide Nano crystalline particles includes a step of calcining at a temperature of about 200 to 11000C for removal of residual organic compounds, HC1 and residual water.
DESCRIPTION OF THE INVENTION
In accordance with the present invention there is provided a method of preparing Nano crystalline particles of Titanium dioxide from Titanium bearing waste residue obtained from the process of manufacturing Ziegler-Natta catalysts.

During the commercial synthesis of Ziegler-Natta catalysts, solvents namely TiC14, and other aliphatic and aromatic solvents are used. The solvents are recovered regularly to maintain the purity of the system and to remove undesired chemical species. The distillation process results in heavy solvent residue generation consisting of a complex mixture of organic, organometallic and inorganic chemical species. The solvent residue is characterized by the presence of titanium, in the form of TiClx (OC2H5)4-x, with x ranging from 0 to 4, TiOCl2 and other titanium containing organomettalic or inorganic components.
The method of preparing the Titanium dioxide Nano crystalline particles in accordance with the present invention comprises the following steps: First step is hydrolyzing a waste residue in a media selected from the group of media consisting of de-mineralized water, mineral acid and alcohol to obtain hydrolyzed mixture.
The media used in hydrolyzing a waste residue consist of 20% to 100% of de-mineralized water, 0 to 20% of mineral acid and 0 to 80% of alcohol. Preferably, the media consist of 60% to 100% of de-mineralized water, 0 to 5% of mineral acid and 0 to 40% of alcohol.
Typically, the mineral acid is at least one acid selected from the group consisting of hydrochloric acid, sulphuric acid and nitric acid,
Typically, the alcohol is at least one alcohol selected from the group consisting of aliphatic alcohols such as methanol, ethanol and propanol.
The hydrolyzed mixture is then subjected to aging to obtain an aged hydrolyzed mixture. Typically, the aging of the hydrolyzed mixture is carried out for a period of about 1 to about 10 days.

The aged hydrolyzed mixture is further subjected to decantation and filtration to separate a solid component mixture from liquid. The solid component mixture is then washed with a plurality of washing media. Particularly, the solid component mixture is initially washed with a first washing media to remove at least undesired metal salts. Typically, the first washing media is a mixture of de-mineralized water and dilute mineral acid selected from the group of acids consisting of hydrochloric acid, sulphuric acid and nitric acid.
The solid component mixture is further washed to remove at least organic components with the second washing media. Typically, the second washing media is at least one hydrocarbon selected from the group of hydrocarbons consisting of hydrocarbon solvents which include isopentane, pentane and heptanes.
Finally, the washed solid component mixture is dried to obtain nano crystalline titanium dioxide with crystallite size 2 to lOOnrn and titanium dioxide nano crystalline particles of size ranging from 1 to 25μm.
In accordance with another embodiment of the present invention the method of preparing the Nano crystalline Titanium dioxide particles includes a further step of washing the washed solid component mixture with a low boiling organic solvent.
Typically, the low boiling organic solvent is at least one selected from the group consisting of alcohols, polar solvents and other solvents capable of removing organic impurities.
In accordance with one of the embodiments of the present invention the low boiling organic solvent is at least one alcohol selected from the group consisting of methanol, ethanol, propanol and the like.

In accordance with another embodiment of the present invention the low boiling organic solvent is at least one polar solvent is selected from the group consisting of tetrahydrofuran, acetone, dimethyl ether, diethyl ether and the like.
In accordance with one of the embodiments the method of preparing the Nano crystalline Titanium dioxide particles includes the washing effected at a temperature ranging from room temperature to the refluxing temperature of the washing media.
In accordance with the preferred embodiment of the present invention the waste residue is hydrolyzed in relatively low concentrations wherein the ratio of waste residue to hydrolyzed media ranges between 0.001.1 and 1:1.
In accordance with another embodiment of the present invention the method of preparing Titanium dioxide Nano particles includes a step of calcining at a temperature of about 200 to 1100°C for removal of residual organic compounds, HC1 and residual water.
Following examples illustrate the invention, but are not intended to limit the scope of the present invention.
Example 1
25 ml of Titanium bearing liquid waste residue containing 30% titanium by weight was added drop-wise to de-mineralized water (250 ml) under agitation for hydrolysis. The agitation was continued for 2hours. Then the obtained mixture was kept for aging for 3 days at room temperature. After 3 days, the mixture was decanted followed by filtration to separate a solid component mixture. The solid component mixture obtained was washed with de-mineralized water followed by

washing with methanol. The solid component mixture was further washed with hexane. The washed solid component mixture was then air dried. The dried solid component mixture was further calcined in an oven at 500°C for 3 hours. White powder with yield of 9.3 gm was obtained. The formation of nano crystalline titanium dioxide was confirmed by XRD analysis with crystallite size of 20 nm. The size of the obtained titanium dioxide particles was found to be in the range of about 1 to 5 μrn which was checked by Scanning Electron Microscope (SEM).
Example 2
25 ml of Titanium bearing liquid waste residue containing 30% titanium by weight was added drop-wise to 250 ml of HC1 (prepared in de-mineralized water) having pH 2 under agitation for hydrolysis. The agitation was continued for 2 hours. The obtained mixture was kept for aging for 3 days at room temperature. The mixture was decanted followed by filtration to obtain a solid component mixture. The solid component mixture was washed with de-mineralized water followed by washing with methanol. The solid component mixture was then washed with hexane and air dried. The dried solid component mixture was further calcined in oven at 500°C for 3 hours. White powder with yield of 12.2 gm was obtained.
Example 3
25 ml of Titanium bearing liquid waste residue containing 30% titanium by weight was added drop-wise to a solution containing 175 ml of de-mineralized water and 75 ml of methanol under agitation for hydrolysis. The agitation was continued for 2hrs. The obtained mixture was kept for aging for 3 days at room temperature. The mixture was decanted followed by filtration to obtain a solid component mixture. The product was washed with de-mineralized water followed by washing with methanol. The solid component mixture was then washed with hexane and air

dried. The dried solid component mixture was further calcined in oven at 500°C for 3 hrs. White powder with yield of 11.1 gm was obtained.
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 invention. These and other changes in the preferred embodiment of the invention 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 invention and not as a limitation .

We Claim:
1. A method of preparing Nano crystalline Titanium dioxide particles from Titanium bearing waste residue obtained from the process of manufacturing Ziegler-Natta catalysts, said method of preparing the Titanium dioxide Nano particles comprising the following steps:
i) hydrolyzing a waste residue in a media selected from the group of
media consisting of de-mineralized water, mineral acid and alcohol to
obtain a hydrolyzed mixture;
ii) aging the hydrolyzed mixture to obtain an aged hydrolyzed mixture; iii) subjecting the aged hydrolyzed mixture to decantation and filtration to
separate a solid component mixture from liquid;
iv) washing the solid component mixture with a first washing media to
remove at least undesired metal salts;
v) washing the solid component mixture with a second washing media to
remove at least organic components; and
vi) drying the washed solid component mixture to obtain titanium dioxide
nano crystalline particles with crystallite size ranging from 2 to lOOnm
and particle size ranging from 1 to 25 urn.
2. The method as claimed in claim 1, wherein the media consist of 20% to 100% of de-mineralized water, 0 to 20% of mineral acid and 0 to 80% of alcohol.
3. The method as claimed in claim 1, wherein the media consist of 60 % to 100 % of de-mineralized water, 0 to 5 % of mineral acid and 0 to 40% of alcohol.

4. The method as claimed in any one of the preceding claims, wherein the mineral acid is at least one acid selected from the group consisting of hydrochloric acid, sulphuric acid and nitric acid.
5. The method as claimed in any one the preceding claims, wherein the alcohol is at least one alcohol selected from the group consisting of methanol, ethanol, and propanol.
6. The method as claimed in any one of the preceding claims, wherein the aging of the hydrolyzed mixture is carried out for a period of about 1 to about lO days.
7. The method as claimed in any one of the preceding claims, wherein the first washing media is a mixture of de-mineralized water and dilute mineral acid selected from the group of acids consisting of hydrochloric acid, sulphuric acid and nitric acid.
8. The method as claimed in any one of the preceding claims, wherein the second washing media is at least one hydrocarbon selected from the group of hydrocarbons consisting of isopentane, pentane and heptane.
9. The method as claimed in any one of the preceding claims includes a further step of washing the washed solid component mixture with a low boiling organic solvent.
10. The method as claimed in any one of the preceding claims, wherein the low boiling organic solvent is at least one selected from the group consisting of alcohols, polar solvents and other solvents capable of removing organic impurities.

11. The method as claimed in any one of the preceding claims, wherein the low boiling organic solvent is at least one alcohol selected from the group consisting of methanol, ethanol and propanol.
12. The method as claimed in any one of the preceding claims, wherein the low boiling organic solvent is at least one polar solvent selected from the group consisting of tetrahydrofuran, acetone, dimethyl ether and diethyl ether.
13. The method as claimed in any one of the preceding claims which includes the washing effected at a temperature ranging from room temperature to the refluxing temperature of the washing media.
14. The method as claimed in any one of the preceding claims, wherein the waste residue is hydrolyzed in relatively low concentrations wherein the ratio of waste residue to hydrolyzed media ranges between 0.001:1 and 1:1.
15. The method as claimed in any one of the preceding claims includes a step of calcining at a temperature of about 200 to about 1100°C for removal of residual organic compounds, HC1 and residual water.