Title of Invention	"A PROCESS FOR THE PREPARATION OF A NANOSIZED NOBLE METAL CATALYST USEFUL FOR THE SELECTIVE PREPARATION OF ALIPHATIC DIOL"
Abstract	A process for the preparation of a nanosized noble metal catalyst useful for the selective preparation of aliphatic diol by dissolving a noble metal precursor in a mixture of water and organic solvent, adding to this solution a polymeric colloiding agent, adjusting the pH of the solution to about 4 by adding an alkali solution, and refluxing the solution for 3 to 4 hrs and cooling to obtain the product.

Title of Invention

"A PROCESS FOR THE PREPARATION OF A NANOSIZED NOBLE METAL CATALYST USEFUL FOR THE SELECTIVE PREPARATION OF ALIPHATIC DIOL"

Abstract

A process for the preparation of a nanosized noble metal catalyst useful for the selective preparation of aliphatic diol by dissolving a noble metal precursor in a mixture of water and organic solvent, adding to this solution a polymeric colloiding agent, adjusting the pH of the solution to about 4 by adding an alkali solution, and refluxing the solution for 3 to 4 hrs and cooling to obtain the product.

Full Text	A PROCESS FOR THE PREPARATION OF A NANOSIZED NOBLE METAL CATALYST USEFUL FOR THE SELECTIVE PREPARATION OF ALIPHATIC DIOLS FIELD OF THE INVENTION This invention relates to a process for the preparation of a nanosized noble metal catalyst. More particularly, it relates to the said catalyst composition in the form of a colloidal dispersion which is useful for selective hydrogenation of 1,4 butynediol to 1,4 butenediol. The catalyst is a noble metal e.g. palladium or platinum in the form of colloidal dispersion where the particle size of the catalysts is less than 75 run. PRIOR ART REFERENCES In the prior art, the uses of a number of catalysts are described for producing 1,4 butenediol by hydrogenation of 1,4 butynediol. Most of these patents are based on the combination of palladium with one or more mixed compounds of copper, zinc, calcium, cadmium, lead, alumina, mercury, tellurium, gallium etc. Selective hydrogenation of acetylinic compound is described in GBA 871,804 in a suspension method using Pd catalyst which has been treated with the salt solutions of Zn, Cd, Hg, Ga, Th, In, or Ga. The process is carried out at milder conditions with 97% selectivity for cis 1,2-butenediol and 3% to the trans form. Moreover, use of organic amines has been suggested as promoters in the catalyst system. Lindlar catalyst (lead doped Pd catalyst) is also used for the selective hydrogenation of the acetylinic compounds as described inJJS Patent No. 2,681,938. The drawback of this process is use of additional amines such as pyridine to obtain good selectivity for 1,4 butenediol. Yet another DE patent (DE 1,213,839) describes Pd catalyst doped with Zn salts and ammonia for the partial hydrogenation of acetylinic compounds. But this catalyst suffers from a major drawback of short lifetime due to poisoning. The use of Pd/A^Ch catalyst, which has been treated with carbon monoxide for the hydrogenation of 1,4 butynediol in an inert solvent, is described in DE-A 2,619,660. The disadvantage of this process is that the catalyst is treated with carbon monoxide gas, which is highly toxic and difficult to handle. US Patent No.2, 961,471 describe Raney nickel catalyst for partial hydrogenation of 1,4 butynediol using Raney nickel catalyst. This catalyst gave a low selectivity for 1,4 butenediol. In another, US Patent Na 2 953,604 is described a Pd containing charcoal and copper catalyst for the reduction of 1,4 butynediol to 1,4 butenediol with 81% selectivity for 1,4 butenediol. The drawback of the process is the formation of large A/ - \J/ amount of side products. Another US Patent No. 4,001,344_d>escribes a catalyst for the \ preparation of 1,4 butenediol by hydrogenation of 1,4 butynediol by use of palladium mixed with y-Al2O3 along with, zinc and cadmium or either zinc or cadmium together JT . with bismuth or tellurium. The disadvantage of the said process is the formation of large amount of residues (7.5-12%) which lowers the selectivity of 1,4 butenediol to 88%. In addition to these patents, US Patent Nos. 5,521,139 and 5,728,900 describes the catalyst and a process for the preparation of 1,4 butenediol by the hydrogenation of 1,4 butynediol over a Pd containing catalyst. They have used the fixed bed catalyst, which was prepared by applying Pd and Pb or Pd and Cd successively, by vapor deposition or sputtering, to metal gauze or a metal foil acting as a support. In this process also selectivity obtained for cis 1,4 butenediol is 98%. The disadvantage of these processes is that a trans 1,4 butenediol with residues are also obtained. All the above said catalysts for the hydrogenation of 1,4 butynediol to 1,4 butenediol suffers from the disadvantages such as used promoters like organic amines. Their preparation becomes cumbersome and involves use of sophisticated equipment. All these catalysts reported do not give complete selectivity to the desired product 1,4 butenediol. The formation of side products and residues has also been reported which affect the efficiency of the process and the recovery of pure 1,4 butenediol is difficult. Also these catalysts suffer from short life due to fast deactivation. OBJECT OF THE INVENTION The main object of the present invention is to provide a novel nanosized noble metal catalyst for selective preparation of aliphatic diols. Another object of the present invention is to provide a novel nanosized noble metal catalyst for selective hydrogenation of 1,4 butynediol to 1,4 butenediol. Yet another object of the invention is to provide a process for the preparation of nanosized noble metal catalyst in a colloidal form, useful for selective hydrogenation of 1,4 butynediol to 1,4 butenediol, wherein the noble metal may palladium or platinum and the colloiding agent may be polyvinylpyrrolidone, polyvinylalcohol, polyethyleneamine, polyvinylether, polyethyleneglycol, more preferably polyvinylpyrrolidone at very specific preparation conditions. Still another object is to prepare colloidal dispersion of above-mentioned catalyst having the particle size less than 50 nm. SUMMARY OF THE INVENTION To meet the above objects, the present invention provides nanosized noble metal catalyst for selective preparation of aliphatic diols having a general formula : A/B Wherein A is a polymeric colloiding agent and B is a noble metal The mole ratio of their composition (A/B) may be in the range of 1 - 100, and a process for the preparation of the said catalyst. DETAILED DESCRIPTION OF THE INVENTION The nanosized noble metal catalyst, provided in the present invention is prepared by protecting the noble metal with polymer without poisoning, at very specific preparation conditions. The prepared catalyst is useful for the selective hydrogenation of 1-4 butynediol to 1,4 butenediol at the temperature ranging between 30°C to 90°C and Hb pressure between 200-700 psig. The process of the present invention achieves complete conversion of 1,4 butynediol with 100% selectivity to cis butenediol without any addition of promoter in the substrate solution. Recovery of pure 1,4 butenediol is done by fractional vacuum distillation. The catalyst prepared by this process of the present invention gives complete conversion of 1,4 butynediol with 100% selectivity to 1,4 butenediol, at milder reaction conditions without adding any promoter to the substrate solution. Moreover, the highest purity of 1,4 butenediol is obtained merely by fractional distillation of reaction crude. Accordingly.the present invention provides a process for the preparation of a nanosized noble metal catalyst useful for the selective preparation of aliphatic diols, having a general formula A/B Wherein A is a polymeric colloiding agent and B is a noble metal; the mole ratio of their composition may be in the range of 1-100 which comprises a) dissolving a noble metal precursor in a mixture of water and organic solvent, b) adding to this solution a polymeric colloiding agent, c) adjusting the pH of the solution to about 4 by adding an alkali solution, and d) refluxing the solution for 3 to 4 hrs and cooling to obtain the product. In one of the embodiment of the present invention the noble metal is a palladium or platinum. In yet another embodiment the size of the catalyst is in the range of 10-100 nm. In yet another embodiment the source of palladium or platinum is selected from the group consisting of Palladium or Platinum salts of acetate, bromide and chloride, preferably HfePdCU for palladium and HaPtCle for platinum. In yet another embodiment the colloidal agent is selected from the group -—-zs- •.i.-safc consisting of polyvinylpyrrolidone, polyvinylalcohol, polyethyleneamine, polyvinylether, polyethyleneglycol, and more preferably polyvinylpyrrolidone. In yet another embodiment the organic solvent is selected from methanol, ethanol, isopropanol, 1,4-dioxane and dimethyl ether. In yet another embodiment a mixture of water and organic solvent selected from the group consisting of methanol, ethanol, isopropane, 1,4-dioxane and dimethyl ether is in the ratio of 1-100. . In yet another embodiment a novel nanosized noble metal catalyst as prepared in claim 1 is having a general formula A/B Wherein A is a polymeric colloiding agent » and B is a noble metal; the mole ratio of their composition may be in the range of 1 - 100. In yet another embodiment the noble metal is palladium or platinum. In yet another embodiment the size of the catalyst is in the range of 10-100 nm. In yet another embodiment the source of palladium or platinum is selected from the group consisting of Palladium or Platinum salts of acetate, bromide and chloride, preferably H2PdCl4 for palladium and H2PtCl6 for platinum. In still another embodiment a nanosized noble metal catalyst as prepared is useful for the selective preparation of 1,4 butenediol from 1,4 butynediol. The process of the invention is described in detail in the examples given below which are illustrative only and sjiould not be considered to limit the scope of the invention. EXAMPLE-1 This example illustrates the preparation of nanosized Pd catalyst, wherein the mole ratio of polyvinyl pyrolidone (PVP): Pd is 1:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water give 0.2 mmolar HiPdCU. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 3.33 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol. EXAMPLE-2 This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 10:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar I^PdCU. From this solution, 15 ml of 0.2 mmolar I-^PdCU was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 33.3 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to l,4butenediol. EXAMPLE-3 This example illustrates the preparation of nanosized Pd catalyst, wherein the mole ratio of PVP: Pd is 20:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar H2PdCl4. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 66.6 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to l,4butenediol. EXAMPLE-4 This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 30:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give Q.2 mmolar t^PdCU. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 99.9 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to l,4butenediol. EXAMPLE 5 This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 40:1 and the water to organic solvent ratio is 30:70 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar H2PdCl4. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 133 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol. EXAMPLE 6 This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 40:1 and the water to organic solvent ratio is 50:50 by the following procedure. 67.4 mg of PtCl4 was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar solution of H2PtCl4. From this solution, 15 ml of 0.2 mmolar jytCU was withdrawn and 25 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 133 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs. the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol. EXAMPLE? This example illustrates the preparation of nanosized Pt catalyst wherein the mole ratio of PVP: Pt is 40:1 and the water to organic solvent ratio is 30:70 by the following procedure. 67.4 mg of PtCU was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar solution of F^PtCU. From this solution, 15 ml of 0.2 mmolar HjPtCU was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 133 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol. EXAMPLE-8(TableRemoved) The advantages of the present invention are: 1. Selective hydrogenation of 1,4 butynediol to 1,4 butenediol is achieved by using nanosized noble metal catalysts without poisoning it. 2. The particle size of the catalyst is below 50 nm. 3. Selective preparation of 1,4 butenediol is achieved without any additive or promoter in the substrate solution. 4. No special reduction method for catalyst is needed; the solvent itself reduces the catalyst. 5. Results obtained under milder reaction conditions. 6. Turn over number obtained is in the range of 2-3 x 106 which is higher than that reported in the literature. 7. Recovery of pure 1,4 butenediol is done by fractional vacuum distillation. We claim : 1. A process for the preparation of a nanosized noble metal catalyst useful for the selective preparation of aliphatic diols, having a general formula A/B Wherein A is a polymeric colloiding agent and B is a noble metal; the mole ratio of their composition may be in the range of 1-100 which comprises a) dissolving a noble metal precursor in a mixture of water and organic solvent, b) adding to this solution a polymeric colloiding agent, c) adjusting the pH of the solution to about 4 by adding an alkali solution, and d) refluxing the solution for 3 to 4 hrs and cooling to obtain the product. 2. A process as claimed in claim 1 wherein the noble metal is a palladium or platinum. 3. A process as claimed in claims 1-2 wherein the size of the catalyst is in the range of 10-100 nm. 4. A process as claimed in claims 1-3 wherein the source of palladium or platinum is selected from the group consisting of Palladium or Platinum salts of acetate, bromide and chloride, preferably HaPdCU for palladium and H2PtCI6 for platinum. 5. A process as claimed in claims 1-4 wherein the colloidal agent is selected from the group consisting of polyvinylpyrrolidone, polyvinylalcohol, polyethyleneamine, polyvinylether, polyethyleneglycol, and more preferably polyvinylpyrrolidone. 6. A7 process as claimed in claims 1-5 wherein the organic solvent is selected from methanol, ethanol, isopropanol, 1,4-dioxane and dimethyl ether. . -. t M^ 7. A' process as claimed in claims 1-6 wherein a mixture of water and organic solvent selected from the group consisting of methanol, ethanol, isopropane, 1,4-dioxane and dimenthyl ether is in the ratio of 1-100. 8. A process for the preparation of a nanosized noble metal catalyst useful for the selective preparation of aliphatic diol substantially as herein described with reference to the examples.

Full Text

A PROCESS FOR THE PREPARATION OF A NANOSIZED NOBLE METAL CATALYST USEFUL FOR THE SELECTIVE PREPARATION OF ALIPHATIC DIOLS
FIELD OF THE INVENTION
This invention relates to a process for the preparation of a nanosized noble metal catalyst. More particularly, it relates to the said catalyst composition in the form of a colloidal dispersion which is useful for selective hydrogenation of 1,4 butynediol to 1,4 butenediol. The catalyst is a noble metal e.g. palladium or platinum in the form of colloidal dispersion where the particle size of the catalysts is less than 75 run.
PRIOR ART REFERENCES
In the prior art, the uses of a number of catalysts are described for producing 1,4
butenediol by hydrogenation of 1,4 butynediol. Most of these patents are based on the
combination of palladium with one or more mixed compounds of copper, zinc, calcium,
cadmium, lead, alumina, mercury, tellurium, gallium etc. Selective hydrogenation of
acetylinic compound is described in GBA 871,804 in a suspension method using Pd
catalyst which has been treated with the salt solutions of Zn, Cd, Hg, Ga, Th, In, or Ga.
The process is carried out at milder conditions with 97% selectivity for cis 1,2-butenediol and 3% to the trans form. Moreover, use of organic amines has been suggested as promoters in the catalyst system.
Lindlar catalyst (lead doped Pd catalyst) is also used for the selective hydrogenation of the acetylinic compounds as described inJJS Patent No. 2,681,938. The drawback of this process is use of additional amines such as pyridine to obtain good selectivity for 1,4 butenediol.
Yet another DE patent (DE 1,213,839) describes Pd catalyst doped with Zn salts and
ammonia for the partial hydrogenation of acetylinic compounds. But this catalyst suffers from a major drawback of short lifetime due to poisoning.
The use of Pd/A^Ch catalyst, which has been treated with carbon monoxide for the hydrogenation of 1,4 butynediol in an inert solvent, is described in DE-A 2,619,660. The disadvantage of this process is that the catalyst is treated with carbon monoxide gas, which is highly toxic and difficult to handle.

US Patent No.2, 961,471 describe Raney nickel catalyst for partial hydrogenation of 1,4 butynediol using Raney nickel catalyst. This catalyst gave a low selectivity for 1,4 butenediol. In another, US Patent Na 2 953,604 is described a Pd containing charcoal and copper catalyst for the reduction of 1,4 butynediol to 1,4 butenediol with 81% selectivity for 1,4 butenediol. The drawback of the process is the formation of large A/ - \J/ amount of side products. Another US Patent No. 4,001,344_d>escribes a catalyst for the
\
preparation of 1,4 butenediol by hydrogenation of 1,4 butynediol by use of palladium
mixed with y-Al2O3 along with, zinc and cadmium or either zinc or cadmium together JT . with bismuth or tellurium. The disadvantage of the said process is the formation of large
amount of residues (7.5-12%) which lowers the selectivity of 1,4 butenediol to 88%.
In addition to these patents, US Patent Nos. 5,521,139 and 5,728,900 describes the
catalyst and a process for the preparation of 1,4 butenediol by the hydrogenation of 1,4 butynediol over a Pd containing catalyst. They have used the fixed bed catalyst, which was prepared by applying Pd and Pb or Pd and Cd successively, by vapor deposition or sputtering, to metal gauze or a metal foil acting as a support. In this process also selectivity obtained for cis 1,4 butenediol is 98%. The disadvantage of these processes is that a trans 1,4 butenediol with residues are also obtained.
All the above said catalysts for the hydrogenation of 1,4 butynediol to 1,4 butenediol suffers from the disadvantages such as used promoters like organic amines. Their preparation becomes cumbersome and involves use of sophisticated equipment. All these catalysts reported do not give complete selectivity to the desired product 1,4 butenediol.
The formation of side products and residues has also been reported which affect the efficiency of the process and the recovery of pure 1,4 butenediol is difficult. Also these catalysts suffer from short life due to fast deactivation.
OBJECT OF THE INVENTION
The main object of the present invention is to provide a novel nanosized noble metal catalyst for selective preparation of aliphatic diols.
Another object of the present invention is to provide a novel nanosized noble metal catalyst for selective hydrogenation of 1,4 butynediol to 1,4 butenediol.
Yet another object of the invention is to provide a process for the preparation of nanosized noble metal catalyst in a colloidal form, useful for selective hydrogenation of 1,4 butynediol to 1,4 butenediol, wherein the noble metal may palladium or platinum and the colloiding agent may be polyvinylpyrrolidone, polyvinylalcohol, polyethyleneamine, polyvinylether, polyethyleneglycol, more preferably polyvinylpyrrolidone at very specific preparation conditions.
Still another object is to prepare colloidal dispersion of above-mentioned catalyst having the particle size less than 50 nm.
SUMMARY OF THE INVENTION
To meet the above objects, the present invention provides nanosized noble metal catalyst for selective preparation of aliphatic diols having a general formula :
A/B
Wherein A is a polymeric colloiding agent
and B is a noble metal
The mole ratio of their composition (A/B) may be in the range of 1 - 100, and a process for the preparation of the said catalyst.
DETAILED DESCRIPTION OF THE INVENTION
The nanosized noble metal catalyst, provided in the present invention is prepared
by protecting the noble metal with polymer without poisoning, at very specific
preparation conditions. The prepared catalyst is useful for the selective
hydrogenation of 1-4 butynediol to 1,4 butenediol at the temperature ranging
between 30°C to 90°C and Hb pressure between 200-700 psig. The process of the
present invention achieves complete conversion of 1,4 butynediol with 100%
selectivity to cis butenediol without any addition of promoter in the substrate
solution.
Recovery of pure 1,4 butenediol is done by fractional vacuum distillation.
The catalyst prepared by this process of the present invention gives complete
conversion of 1,4 butynediol with 100% selectivity to 1,4 butenediol, at milder
reaction conditions without adding any promoter to the substrate solution. Moreover,
the highest purity of 1,4 butenediol is obtained merely by fractional distillation of
reaction crude.
Accordingly.the present invention provides a process for the preparation of a
nanosized noble metal catalyst useful for the selective preparation of aliphatic diols,
having a general formula
A/B
Wherein A is a polymeric colloiding agent
and B is a noble metal;
the mole ratio of their composition may be in the range of 1-100 which comprises
a) dissolving a noble metal precursor in a mixture of water and organic
solvent,
b) adding to this solution a polymeric colloiding agent,
c) adjusting the pH of the solution to about 4 by adding an alkali solution,
and
d) refluxing the solution for 3 to 4 hrs and cooling to obtain the product.
In one of the embodiment of the present invention the noble metal is a palladium or
platinum.
In yet another embodiment the size of the catalyst is in the range of 10-100 nm.
In yet another embodiment the source of palladium or platinum is selected from
the group consisting of Palladium or Platinum salts of acetate, bromide and chloride, preferably HfePdCU for palladium and HaPtCle for platinum.
In yet another embodiment the colloidal agent is selected from the group
-—-zs- •.i.-safc
consisting of polyvinylpyrrolidone, polyvinylalcohol, polyethyleneamine,
polyvinylether, polyethyleneglycol, and more preferably polyvinylpyrrolidone.
In yet another embodiment the organic solvent is selected from methanol, ethanol, isopropanol, 1,4-dioxane and dimethyl ether.
In yet another embodiment a mixture of water and organic solvent selected from the group consisting of methanol, ethanol, isopropane, 1,4-dioxane and dimethyl ether is in the ratio of 1-100.
. In yet another embodiment a novel nanosized noble metal catalyst as prepared in claim 1 is having a general formula
A/B
Wherein A is a polymeric colloiding agent » and B is a noble metal; the mole ratio of their composition may be in the range of 1 - 100.
In yet another embodiment the noble metal is palladium or platinum.
In yet another embodiment the size of the catalyst is in the range of 10-100 nm.
In yet another embodiment the source of palladium or platinum is selected from the group consisting of Palladium or Platinum salts of acetate, bromide and
chloride, preferably H2PdCl4 for palladium and H2PtCl6 for platinum.
In still another embodiment a nanosized noble metal catalyst as prepared is useful for the selective preparation of 1,4 butenediol from 1,4 butynediol.
The process of the invention is described in detail in the examples given below which are illustrative only and sjiould not be considered to limit the scope of the invention.
EXAMPLE-1
This example illustrates the preparation of nanosized Pd catalyst, wherein the mole ratio of polyvinyl pyrolidone (PVP): Pd is 1:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water give 0.2 mmolar HiPdCU. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 3.33 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol.
EXAMPLE-2
This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 10:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar I^PdCU. From this solution, 15 ml of 0.2 mmolar I-^PdCU was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 33.3 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs.
After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to l,4butenediol.
EXAMPLE-3
This example illustrates the preparation of nanosized Pd catalyst, wherein the mole ratio of PVP: Pd is 20:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar H2PdCl4. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 66.6 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to l,4butenediol.
EXAMPLE-4
This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 30:1 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give Q.2 mmolar t^PdCU. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 99.9 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to l,4butenediol.
EXAMPLE 5
This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 40:1 and the water to organic solvent ratio is 30:70 by the following procedure. 35.5 mg of palladium chloride was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar H2PdCl4. From this solution, 15 ml of 0.2 mmolar H2PdCl4 was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 133 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol.
EXAMPLE 6
This example illustrates the preparation of nanosized Pd catalyst wherein the mole ratio of PVP: Pd is 40:1 and the water to organic solvent ratio is 50:50 by the following procedure. 67.4 mg of PtCl4 was dissolved in 5 ml of concentrated hydrochloric acid and was diluted to 100 ml by adding water to give 0.2 mmolar solution of H2PtCl4. From this solution, 15 ml of 0.2 mmolar jytCU was withdrawn and 25 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 133 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs. the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol.
EXAMPLE?
This example illustrates the preparation of nanosized Pt catalyst wherein the mole ratio of PVP: Pt is 40:1 and the water to organic solvent ratio is 30:70 by the following procedure. 67.4 mg of PtCU was dissolved in 5 ml of concentrated hydrochloric acid and was diluted
to 100 ml by adding water to give 0.2 mmolar solution of F^PtCU. From this solution, 15 ml of 0.2 mmolar HjPtCU was withdrawn and 15 ml of ethyl alcohol was added. The pH of the solution was increased to 4 by adding 10% NaOH solution. To this solution 133 mg of PVP was added, then the solution was diluted to 50 ml by adding water and the mixture was refluxed for 3 hrs. After 3 hrs the solution was cooled and directly used for hydrogenation of 1,4 butynediol to 1,4 butenediol.
EXAMPLE-8(TableRemoved)
The advantages of the present invention are:
1. Selective hydrogenation of 1,4 butynediol to 1,4 butenediol is achieved by using
nanosized noble metal catalysts without poisoning it.
2. The particle size of the catalyst is below 50 nm.
3. Selective preparation of 1,4 butenediol is achieved without any additive or promoter in
the substrate solution.
4. No special reduction method for catalyst is needed; the solvent itself reduces the
catalyst.
5. Results obtained under milder reaction conditions.
6. Turn over number obtained is in the range of 2-3 x 106 which is higher than that
reported in the literature.
7. Recovery of pure 1,4 butenediol is done by fractional vacuum distillation.

We claim :
1. A process for the preparation of a nanosized noble metal catalyst useful
for the selective preparation of aliphatic diols, having a general formula
A/B
Wherein A is a polymeric colloiding agent
and B is a noble metal;
the mole ratio of their composition may be in the range of 1-100
which comprises
a) dissolving a noble metal precursor in a mixture of water and organic
solvent,
b) adding to this solution a polymeric colloiding agent,
c) adjusting the pH of the solution to about 4 by adding an alkali solution,
and
d) refluxing the solution for 3 to 4 hrs and cooling to obtain the product.
2. A process as claimed in claim 1 wherein the noble metal is a palladium or
platinum.
3. A process as claimed in claims 1-2 wherein the size of the catalyst is in
the range of 10-100 nm.
4. A process as claimed in claims 1-3 wherein the source of palladium or
platinum is selected from the group consisting of Palladium or Platinum
salts of acetate, bromide and chloride, preferably HaPdCU for palladium
and H2PtCI6 for platinum.
5. A process as claimed in claims 1-4 wherein the colloidal agent is selected
from the group consisting of polyvinylpyrrolidone, polyvinylalcohol,

polyethyleneamine, polyvinylether, polyethyleneglycol, and more preferably polyvinylpyrrolidone.
6. A7 process as claimed in claims 1-5 wherein the organic solvent is
selected from methanol, ethanol, isopropanol, 1,4-dioxane and dimethyl
ether. .
-. t M^
7. A' process as claimed in claims 1-6 wherein a mixture of water and
organic solvent selected from the group consisting of methanol, ethanol,
isopropane, 1,4-dioxane and dimenthyl ether is in the ratio of 1-100.
8. A process for the preparation of a nanosized noble metal catalyst useful
for the selective preparation of aliphatic diol substantially as herein
described with reference to the examples.

Documents:

1073-del-2000-abstract.pdf

1073-del-2000-claims.pdf

1073-del-2000-correspondence-others.pdf

1073-del-2000-correspondence-po.pdf

1073-del-2000-description (complete).pdf

1073-del-2000-form-1.pdf

1073-del-2000-form-19.pdf

1073-del-2000-form-2.pdf

1073-del-2000-form-3.pdf

1073-del-2000-petition-138.pdf

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Patent Number

218357

Indian Patent Application Number

1073/DEL/2000

PG Journal Number

21/2008

Publication Date

23-May-2008

Grant Date

31-Mar-2008

Date of Filing

29-Nov-2000

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	CHANDRASHEKHAR VASANT RODE	NATIONAL CHEMICAL LABORATORY, PUNE 411 008, MAHARASHTRA STATE, INDIA,
2	MANISHA MADHUKAR TELKAR	NATIONAL CHEMICAL LABORATORY, PUNE 411 008, MAHARASHTRA STATE, INDIA,
3	RAGHUNATH VITTHAL CHAUDHARI	NATIONAL CHEMICAL LABORATORY, PUNE 411 008, MAHARASHTRA STATE, INDIA,

PCT International Classification Number

B01J 35/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA