Indian Patents. 221970:"A NOVEL SOLID STATE THERMAL PROCESS FOR THE SYNTHESIS OF LITHIUM HEXAFLUORO PHOSPHATE (LiPF6) USEFUL AS BATTERY ELECTROLYTE"

Title of Invention	"A NOVEL SOLID STATE THERMAL PROCESS FOR THE SYNTHESIS OF LITHIUM HEXAFLUORO PHOSPHATE (LiPF6) USEFUL AS BATTERY ELECTROLYTE"
Abstract	A process for the preparation of Lithium hexafluoro Phosphate (LiPF6)which is useful as a battery electrolyte especially for rocking chair cells and other primary non-aqueous lithium based cells and solid state and solid polymer electrolyte lithium cells.

Full Text	process for the preparation of Lithium hexafluoro phosphate (LiPF6) which is useful as a battery electrolyte especially for rocking chair cells and other primary non-aqueous lithium based cells and solid state and solid polymer electrolyte lithium cells. L;PF6 is a well-known electrolyte for secondary lithium based cells which is difficult to prepare because of very active raw materials like P205, Li2O and PF5 and F2 gases. There are a few chemical procedures available in literature however, they need careful purification and handling. Moreover, such procedures require a wide range of equipment to operate and prepare this essential chemical for rocking chair or lithium ion or intercalation battery systems. Metal fluorides of phosphorous viz. MPF6 where M is Ca, K or Li can be prepared by reacting MF with PF3. (Paul et. al., Fluorine Chemistiy, 56, 1995). Hence, 3MF + 5PF3 —3MPF6 ± 2P Where M is Ca, K or Cs MPF6 can be prepared by neutralising HPF6 with appropriate base viz., 2HPF6 + Ca(OH)2 — Ca(MF6)2 + 2 H20 Similarly some of the hexafluorophosphates can be prepared by double decomposition of NH4PF6 or KPF6 .( Paul et. al., Fluorine Chemistiy, 56, 1995; Fluorine Chemistry, Vol. 5,Simons J.H., 131(1819), 1964; Fluorine Chemistry, Vol. 1, Emelson H.J., 76(219), 1995) LiPF6 prepared by earlier methods suffer has certain disadvantages like, they need toxic chemicals as reactants, it becomes difficult to handle the chemicals involved, the final product contains unreacted impurities, it is a partial reaction, it needs further steps for preparation and it is not a pure solid state reaction. The main object of this present invention is to provide a novel method for the synthesis of (LiPF6) lithiumhexafluorophosphate as a battery electrolyte. Another object of this present invention is to provide a complete solid state reaction. Still another object of this present invention is to avoid many active chemicals which are difficult to handle. Yet another object of this invention is to avoid obnoxious gases. Still yet another object of this invention is to get the product without any partial reaction. 2 These and other objects of the invention are achieved and the problems associated with the prior art are overcome by the process of the invention described below. A novel method for the preparation of LiPF6 (lithium hexafluoro phosphate) is developed where in equimolar quantities of pure dry AR lithium source such as Li2O or Li2CO3 or LiNO3 is mixed with (very pure dry and AR samples) diammonium hydrogen phosphate and the mixture was heated to 200~ — 6000C continuously for 6 hours in an electric furnace. The product was cooled and was then transferred into a dry vessel. The product was a transparent substance which was confirmed by X-ray analysis as LiAsF6. Accordingly, the present invention provides a novel solid state thermal process for the synthesis of lithium hexafluoro phophate (LiPF6), which comprises of: (a) mixing a lithium source selected from the group consisting of a lithium oxide, a lithium salt and a combination thereof with diammonium phosphate in equimolar proportions; (b) heating the mixture in a furnace at a temperature in the range of 1 500C to 6000C continuously to obtain LiPO3; (c) cooling and powdering the LiPO3 (d) mixing of the powdered product with six to nine times quantitatively of ammonium fluoride and then heating it at a temperature in the range of 1 500C to 2000C using a furnace continuously for 4-6 hours in a closed Teflon container; (e) transferring the product to a dry vessel. In one embodiment of the invention, step (b) above is carried out for a time in the range of 4 to 6 hours. In an embodiment of the present invention LiPO3 is mixed with NH4F in the ratio 1:6-9 to form LiPF6. In another embodiment of the present invention, lithium meta phosphate (LiPO3) is 0 mixed with ammonium fluoride in a ratio of 1:7 and the mixture heated to 200 C in an electric furnace for 6 hours continuously to get lithium hexafluoro phosphate. In yet another embodiment of the present invention Li2CO3 or Li2O or LiNO3 is mixed with diammonium hydrogen phosphate and ammonium fluoride in the molar ratios 1:2:6-9 In another embodiment of the present invention Li2CO3 or Li2O or LiNO3 is mixed with diammonium hydrogen phosphate and ammonium fluoride in the ratio of 1:1:7. 3 In yet another embodiment of the present invention, Li2O or LiNO3 is mixed with diammonium hydrogen phosphate and ammonium fluoride in the ratio 1:1:7 and the mixture is heated at 2000C continuously for 12 hours in an electric furnace to obtain LiPF6. In an embodiment of the present invention Li2CO3 or Li2O or LiNO3 is mixed with diammonium phosphate in the ratio 1:1 and then, the product is mixed with NI-hF in the ratio of 1:7 and heated. In still another embodiment of this invention the temperature is kept between 150-3500C for the preparation of LiPF6 when LiNO3 or Li2O in the starting material. In another embodiment of the invention, for Li2CO3 the temperature of heating with (NH4)2HP04 is around 6000C and subsequently with NH4F mixed and heating the temperature is kept in between 1 50-3500C. In another embodiment of the invention, the reactions occur in solid state. In yet another embodiment of the invention, the process comprises a two step reaction as follows: (a) 3000C 2 (NH4)2HP04 + Li2O —* 2 LiPO3 + 4NH3 + 3H20 6000C 2 (NH42HPO4 + Li2CO3 -+ 2 LiPO3 + 4NH3 ±C02 + 3H20 3000C 2 (NH4)2HP04 + 2 LiNO3 —* 2 LiPO3 + 4NH3 + 2N02±2H20 +02 >150-3000C (b) LiPO3 + 6NH4F —* LiPF6 + 6NH3 ±3H20 In yet another embodiment of this invention a single step process is possible at a temperature> 1 50-3000C. Li2O + 2 (NH4)2HP04 + 12 NH4F —2 LiPF6 + 16NH3 + 9H20 Li2CO3 + 2 (NH4)2HP04 + 12 NH4F —> 2 LiPF6 + 16NH3 + C02±9H20 LiNO3 + 2 (NH4)2HP04 + 12 NH4F — 2 LiPF6 + 1 6NH3 ± N02+9H20 In another embodiment of the present invention, pure dry Li2O or Li2CO3 or LiNO3 is mixed with twice the quantity of diammonium phosphate i.e., in the molar ratio of 1:2 and the mixture is heated in an electric or muffle furnace for 6 hours at a temperature of 6000C continuously for Li2CO3 and around 3000C for Li2O and LiNO3. The product was dried at 4 800C'~nd was then allowed to react with NH4F in the molar ratio of 1: > 6 - 8 for 4 hours in an electric furnace continuously at a temperature range of 150 - 350~ In yet another embodiment of this invention all materials are in solid state conditions. It is a feature of this invention that an electrical furnace can be used for the process. It is another feature of this invention that a muffle furnace can be used for the process. In yet another embodiment of this invention a single step process is possible viz., >1 50-3000C (a) LiPO3 + 6 NH4F —* LiPF6 + 6NH3 + 3H20 Lithium hexafluoro phosphate, is an essential chemical for rocking chair cells, lithium ion cells or intercalation battery systems. However, the process for preparing this compound by earlier methods is difficult and has many drawbacks. The present invention relates to a novel solid state thermal process for the preparation of LiPF6, which overcomes the previous difficulties. It comprises of a solid state reaction of a lithium salt or a lithium oxide or a combination of both with diammonium phosphate in equimolar proportions obtaining a mixture of the two compounds. The mixture is then heated in a furnace at 6000C and the product obtained is powdered after cooling. It is then mixed with ammonium fluoride six times the quantity of LiPO3 obtained, from the reaction, and then heated at 2000C using a furnace continuously for 4-6 hours in a closed Teflon container. The main advantages of the present invention are that first, there are no side reactions, second a single step or double step process can be possible depending on the method of approach, third, a pure sample of LiPF6 is obtained, fourth, it is a purely solid state reaction under thermal control as no gases or liquids are used even for the initial reaction, fifth, the purity of the product depends on the purity of the reactants and last, the process is simple, uncomplicated and highly efficient. The invention will now be described in greater detail with reference to the following examples, which are illustrative and therefore should not be construed as limiting the scope of the present invention in any manner: Example 1 An equimolar mixture of Li2CO3 (AR) and (NH4)2HP04 (AR) are ground well and mixed together and heated to 6000C in an electric / muffle furnace for 6 hours continuously 5 and then product was ground well and mixed with NH4F (AR) and the mixture was heated again in the electrical furnace / muffle furnace for 4 hours at a temperature of 2000C. Components Composition First step Li2CO3 0.74g (NH4)2HP04 1.32g Particle size of the mixture 5 mji Temperature 6000C Time 6 hours Second step NH4F 2.6g Temperature 6000C Time 4 hours Nature of the product transparent Efficiency of the process > 90% Example 2 An equimolar mixture of Li2O (AR) and (NH4)2HP04 (AR) are ground well and mixed together and heated to 6000C in an electric / muffle furnace for 6 hours continuously and then product was ground well and mixed with NH4F (AR) and the mixture was heated again in the electrical furnace / muffle furnace for 4 hours at a temperature of 2000C. Components Composition First step Li2O 0.3g (NH4)2HP04 1.32g Particle size of the mixture 5 m~i. Temperature 4000C Time 6 hours Second step NH4F 2.6g Temperature 2000C Time 4 hours Nature of the product transparent Efficiency of the process > 90% 6 * Example 3 An equimolar mixture of LiNO3 (AR) and (NH4)2HP04 (AR) are ground well and mixed together and heated to 4000C in an electric / muffle furnace for 6 hours continuously and then product was ground well and mixed with NH4F (AR) and the mixture was heated again in the electrical furnace / muffle furnace for 4 hours at a temperature of 2000C. Components Composition First step LiNO3 0.69g (NH4)2HP04 1 .32g Particle size of the mixture 5 m~i. Temperature 4000C Time 6 hours Second step NH4F 2.6g Temperature 2000C Time 4 hours Nature of the product transparent Efficiency of the process > 90% Example 4 An equimolar mixture of lithium meta phosphate (LiPO3) and ammonium fluoride in the ratio 1: > 6-8 is taken and then mixed and ground well and then heated in an electric / muffle furnace then the temperature of heating was continued for 4 hours at 2000C till the final product was formed. Components Composition First step LiNO3 0.69g (NH4)2HP04 1 .32g Particle size of the mixture 5 mu. Temperature 6000C Time 6 hours Second step NH4F 2 .6g Temperature 6000C Time 4 hours 7 Natun of the product transparent Efficiency of the process > 90% Example 5 Li2O, (NH4)2HP04 (AR) and NI-hF mixture is taken in the ratio of 1:2:7 and the mixed material is heated in an electric / muffle furnace for 6 hours at a temperature of 3000C continuously. Components Composition Li2O 0.30g (NH42HPO4 1 .32g NH4F 2 .60g Particle size of the mixture 5 mu. Temperature 3000C Time 6 hours Nature of the product transparent Efficiency of the process > 90% Example 6 Li2CO3 , (NH4)2HP04 (AR) and NH4F mixture is taken in the ratio of 1:2:7 and the mixed material is heated in an electric / muffle furnace for 6 hours at a temperature of 3000C continuously. Components Composition Li2CO3 0.74g (NH4)2HP04 1 .32g NH4F 2.60g Particle size of the mixture 5 mu. Time 6 hours Temperature 6000C Nature of the product transparent Efficiency of the process > 90% Example 7 LiNO3 , (NH4)2HP04 (AR) and NH4F mixture is taken in the ratio of 1:2:7 and the mixed material is heated in an electric / muffle furnace for 4 hours at a temperature of 3000C continuously 8 Cbm~onents LiNO3 (NH4)2HP04 NH4F Particle size of the mixture Time Temperature Nature of the product Efficiency of the process Composition 0.69g 1.32g 2.60g 5 mu. 4 hours 3000C transparent > 90% 9

Full Text

process for the preparation of Lithium hexafluoro phosphate (LiPF6) which is useful as a battery electrolyte especially for rocking chair cells and other primary non-aqueous lithium based cells and solid state and solid polymer electrolyte lithium cells.

L;PF6 is a well-known electrolyte for secondary lithium based cells which is difficult to prepare because of very active raw materials like P205, Li2O and PF5 and F2 gases. There are a few chemical procedures available in literature however, they need careful purification and handling. Moreover, such procedures require a wide range of equipment to operate and prepare this essential chemical for rocking chair or lithium ion or intercalation battery systems.

Metal fluorides of phosphorous viz. MPF6 where M is Ca, K or Li can be prepared by reacting MF with PF3. (Paul et. al., Fluorine Chemistiy, 56, 1995).

Hence,

3MF + 5PF3 —*3MPF6 ± 2P

Where M is Ca, K or Cs MPF6 can be prepared by neutralising HPF6 with appropriate base viz.,

2HPF6 + Ca(OH)2 —* Ca(MF6)2 + 2 H20

Similarly some of the hexafluorophosphates can be prepared by double decomposition of NH4PF6 or KPF6 .( Paul et. al., Fluorine Chemistiy, 56, 1995; Fluorine Chemistry, Vol. 5,Simons J.H., 131(1819), 1964; Fluorine Chemistry, Vol. 1, Emelson H.J., 76(219), 1995)

LiPF6 prepared by earlier methods suffer has certain disadvantages like, they need toxic chemicals as reactants, it becomes difficult to handle the chemicals involved, the final product contains unreacted impurities, it is a partial reaction, it needs further steps for preparation and it is not a pure solid state reaction.

The main object of this present invention is to provide a novel method for the synthesis of (LiPF6) lithiumhexafluorophosphate as a battery electrolyte.

Another object of this present invention is to provide a complete solid state reaction.

Still another object of this present invention is to avoid many active chemicals which are difficult to handle.

Yet another object of this invention is to avoid obnoxious gases.

Still yet another object of this invention is to get the product without any partial reaction.

2

These and other objects of the invention are achieved and the problems associated with the prior art are overcome by the process of the invention described below.

A novel method for the preparation of LiPF6 (lithium hexafluoro phosphate) is developed where in equimolar quantities of pure dry AR lithium source such as Li2O or Li2CO3 or LiNO3 is mixed with (very pure dry and AR samples) diammonium hydrogen phosphate and the mixture was heated to 200~ — 6000C continuously for 6 hours in an electric furnace. The product was cooled and was then transferred into a dry vessel. The product was a transparent substance which was confirmed by X-ray analysis as LiAsF6.

Accordingly, the present invention provides a novel solid state thermal process for the synthesis of lithium hexafluoro phophate (LiPF6), which comprises of:

(a) mixing a lithium source selected from the group consisting of a lithium oxide, a lithium salt and a combination thereof with diammonium phosphate in equimolar proportions;

(b) heating the mixture in a furnace at a temperature in the range of 1 500C to 6000C continuously to obtain LiPO3;

(c) cooling and powdering the LiPO3

(d) mixing of the powdered product with six to nine times quantitatively of ammonium fluoride and then heating it at a temperature in the range of 1 500C to 2000C using a furnace continuously for 4-6 hours in a closed Teflon container;

(e) transferring the product to a dry vessel.

In one embodiment of the invention, step (b) above is carried out for a time in the range of 4 to 6 hours.

In an embodiment of the present invention LiPO3 is mixed with NH4F in the ratio 1:6-9 to form LiPF6.

In another embodiment of the present invention, lithium meta phosphate (LiPO3) is
0
mixed with ammonium fluoride in a ratio of 1:7 and the mixture heated to 200 C in an

electric furnace for 6 hours continuously to get lithium hexafluoro phosphate.

In yet another embodiment of the present invention Li2CO3 or Li2O or LiNO3 is mixed with diammonium hydrogen phosphate and ammonium fluoride in the molar ratios 1:2:6-9

In another embodiment of the present invention Li2CO3 or Li2O or LiNO3 is mixed with diammonium hydrogen phosphate and ammonium fluoride in the ratio of 1:1:7.

3

In yet another embodiment of the present invention, Li2O or LiNO3 is mixed with diammonium hydrogen phosphate and ammonium fluoride in the ratio 1:1:7 and the mixture is heated at 2000C continuously for 12 hours in an electric furnace to obtain LiPF6.

In an embodiment of the present invention Li2CO3 or Li2O or LiNO3 is mixed with diammonium phosphate in the ratio 1:1 and then, the product is mixed with NI-hF in the ratio of 1:7 and heated.

In still another embodiment of this invention the temperature is kept between 150-3500C for the preparation of LiPF6 when LiNO3 or Li2O in the starting material.

In another embodiment of the invention, for Li2CO3 the temperature of heating with (NH4)2HP04 is around 6000C and subsequently with NH4F mixed and heating the temperature is kept in between 1 50-3500C.

In another embodiment of the invention, the reactions occur in solid state.

In yet another embodiment of the invention, the process comprises a two step reaction as follows:
(a) 3000C
2 (NH4)2HP04 + Li2O —* 2 LiPO3 + 4NH3 + 3H20

6000C
2 (NH42HPO4 + Li2CO3 -+ 2 LiPO3 + 4NH3 ±C02 + 3H20

3000C
2 (NH4)2HP04 + 2 LiNO3 —* 2 LiPO3 + 4NH3 + 2N02±2H20 +02

>150-3000C
(b) LiPO3 + 6NH4F —* LiPF6 + 6NH3 ±3H20

In yet another embodiment of this invention a single step process is possible at a temperature> 1 50-3000C.

Li2O + 2 (NH4)2HP04 + 12 NH4F —*2 LiPF6 + 16NH3 + 9H20

Li2CO3 + 2 (NH4)2HP04 + 12 NH4F —> 2 LiPF6 + 16NH3 + C02±9H20

LiNO3 + 2 (NH4)2HP04 + 12 NH4F —* 2 LiPF6 + 1 6NH3 ± N02+9H20

In another embodiment of the present invention, pure dry Li2O or Li2CO3 or LiNO3 is mixed with twice the quantity of diammonium phosphate i.e., in the molar ratio of 1:2 and the mixture is heated in an electric or muffle furnace for 6 hours at a temperature of 6000C continuously for Li2CO3 and around 3000C for Li2O and LiNO3. The product was dried at

4

800C'~nd was then allowed to react with NH4F in the molar ratio of 1: > 6 - 8 for 4 hours in an electric furnace continuously at a temperature range of 150 - 350~

In yet another embodiment of this invention all materials are in solid state conditions.

It is a feature of this invention that an electrical furnace can be used for the process.

It is another feature of this invention that a muffle furnace can be used for the process.

In yet another embodiment of this invention a single step process is possible viz.,

>1 50-3000C
(a) LiPO3 + 6 NH4F —* LiPF6 + 6NH3 + 3H20

Lithium hexafluoro phosphate, is an essential chemical for rocking chair cells, lithium ion cells or intercalation battery systems. However, the process for preparing this compound by earlier methods is difficult and has many drawbacks.

The present invention relates to a novel solid state thermal process for the preparation of LiPF6, which overcomes the previous difficulties. It comprises of a solid state reaction of a lithium salt or a lithium oxide or a combination of both with diammonium phosphate in equimolar proportions obtaining a mixture of the two compounds. The mixture is then heated in a furnace at 6000C and the product obtained is powdered after cooling. It is then mixed with ammonium fluoride six times the quantity of LiPO3 obtained, from the reaction, and then heated at 2000C using a furnace continuously for 4-6 hours in a closed Teflon container.

The main advantages of the present invention are that first, there are no side reactions, second a single step or double step process can be possible depending on the method of approach, third, a pure sample of LiPF6 is obtained, fourth, it is a purely solid state reaction under thermal control as no gases or liquids are used even for the initial reaction, fifth, the purity of the product depends on the purity of the reactants and last, the process is simple, uncomplicated and highly efficient.

The invention will now be described in greater detail with reference to the following examples, which are illustrative and therefore should not be construed as limiting the scope of the present invention in any manner:

Example 1

An equimolar mixture of Li2CO3 (AR) and (NH4)2HP04 (AR) are ground well and mixed together and heated to 6000C in an electric / muffle furnace for 6 hours continuously

5

and then product was ground well and mixed with NH4F (AR) and the mixture was heated again in the electrical furnace / muffle furnace for 4 hours at a temperature of 2000C.
Components Composition
First step
Li2CO3 0.74g
(NH4)2HP04 1.32g
Particle size of the mixture 5 mji
Temperature 6000C
Time 6 hours
Second step
NH4F 2.6g
Temperature 6000C
Time 4 hours
Nature of the product transparent
Efficiency of the process > 90%

Example 2

An equimolar mixture of Li2O (AR) and (NH4)2HP04 (AR) are ground well and

mixed together and heated to 6000C in an electric / muffle furnace for 6 hours continuously

and then product was ground well and mixed with NH4F (AR) and the mixture was heated

again in the electrical furnace / muffle furnace for 4 hours at a temperature of 2000C.
Components Composition

First step
Li2O 0.3g
(NH4)2HP04 1.32g
Particle size of the mixture 5 m~i.
Temperature 4000C
Time 6 hours
Second step
NH4F 2.6g
Temperature 2000C
Time 4 hours
Nature of the product transparent
Efficiency of the process > 90%

6

* Example 3

An equimolar mixture of LiNO3 (AR) and (NH4)2HP04 (AR) are ground well and

mixed together and heated to 4000C in an electric / muffle furnace for 6 hours continuously

and then product was ground well and mixed with NH4F (AR) and the mixture was heated

again in the electrical furnace / muffle furnace for 4 hours at a temperature of 2000C.
Components Composition

First step
LiNO3 0.69g
(NH4)2HP04 1 .32g
Particle size of the mixture 5 m~i.
Temperature 4000C
Time 6 hours
Second step
NH4F 2.6g
Temperature 2000C
Time 4 hours
Nature of the product transparent
Efficiency of the process > 90%

Example 4

An equimolar mixture of lithium meta phosphate (LiPO3) and ammonium fluoride in the ratio 1: > 6-8 is taken and then mixed and ground well and then heated in an electric / muffle furnace then the temperature of heating was continued for 4 hours at 2000C till the final product was formed.
Components Composition

First step

LiNO3 0.69g

(NH4)2HP04 1 .32g

Particle size of the mixture 5 mu. Temperature 6000C Time 6 hours Second step

NH4F 2 .6g Temperature 6000C Time 4 hours

7

Natun of the product transparent
Efficiency of the process > 90%

Example 5

Li2O, (NH4)2HP04 (AR) and NI-hF mixture is taken in the ratio of 1:2:7 and the mixed

material is heated in an electric / muffle furnace for 6 hours at a temperature of 3000C

continuously.
Components Composition
Li2O 0.30g
(NH42HPO4 1 .32g
NH4F 2 .60g
Particle size of the mixture 5 mu.
Temperature 3000C
Time 6 hours
Nature of the product transparent
Efficiency of the process > 90%

Example 6

Li2CO3 , (NH4)2HP04 (AR) and NH4F mixture is taken in the ratio of 1:2:7 and the

mixed material is heated in an electric / muffle furnace for 6 hours at a temperature of 3000C

continuously.
Components Composition
Li2CO3 0.74g
(NH4)2HP04 1 .32g
NH4F 2.60g
Particle size of the mixture 5 mu.
Time 6 hours
Temperature 6000C
Nature of the product transparent
Efficiency of the process > 90%

Example 7

LiNO3 , (NH4)2HP04 (AR) and NH4F mixture is taken in the ratio of 1:2:7 and the mixed material is heated in an electric / muffle furnace for 4 hours at a temperature of 3000C continuously

8

Cbm~onents

LiNO3

(NH4)2HP04

NH4F

Particle size of the mixture

Time

Temperature

Nature of the product

Efficiency of the process

Composition

0.69g

1.32g

2.60g

5 mu.

4 hours

3000C

transparent

> 90%
9

Documents:

156-DEL-2002-Abstract-(05-11-2007).pdf

156-DEL-2002-Claims-(05-11-2007).pdf

156-DEL-2002-Correspondence-Others-(05-11-2007).pdf

156-DEL-2002-Description (Complete)-(05-11-2007).pdf

156-DEL-2002-Drawings-(05-11-2007).pdf

156-DEL-2002-Form-2-(05-11-2007).pdf

156-DEL-2002-Form-3-(05-11-2007).pdf

abstract.pdf

claim.pdf

complete specification.pdf

correspondence po.pdf

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Patent Number

221970

Indian Patent Application Number

0156/DEL/2002

PG Journal Number

32/2008

Publication Date

08-Aug-2008

Grant Date

12-Jul-2008

Date of Filing

28-Feb-2002

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	ANGAIAH SUBRAMANIAM	EXTENDED SRF, DEPT. OF INDUSTRIAL CHEMISTRY ALGAPPA UNIVERSITY, KARAIKUDI 630003.
2	THIAGARAJAN VASUDEVAN	PROF. & HEAD, ALGAPPA UNIVERSITY, KARAIKUDI 630001
3	RAMAIYER GANGADHARAN	EMERITUS SCIENTIST, ALGAPPA UNIVERSITY, KARAIKUDI 630003.

PCT International Classification Number

C01B 25/10

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA