Title of Invention

"PALLADIUM IMPREGNATED CARBON FOR REMOVAL OF CARBON MONOXIDE GAS"

Abstract A palladium impregnated carbon for removal of carbon monoxide gas comprises activated granular carbon with granular particle size 18 X 40 British Sieve Size (BSS), and surface area 800 to 1500 m2/ g, and having palladium uniformly disposed over the said carbon surface and they are in the ratio by weight of C: Pd = 99:1 to 85:15. A process for preparation of palladium impregnated carbon for removal of carbon monoxide gas comprises of the following steps: a) acidifying activated carbon with 8 to 14 % nitric acid in the ratio 1 : 4 to 1 :6 (w/v) at 50 to 80°C for 5 to 10 hours to generate acidic functional group over the carbon surface, b) washing the acidified carbon with deionized water to make it neutral (pH 7), and drying it in an oven at 100 to 120°C preferably at 110°C for 3 to 6 hours (preferably 4 hours) followed by cooling in desiccator, c) pouring carbon b) having acidic functional group into distilled water in the (w/v) ratio of 1 : 8 to 1 : 16 and heating at 60 to 90°C for 10 to 25 minutes, d) producing the acidic solution of palladium chloride by adding concentrated hydrochloric acid and distilled water in the ratio (w/v/v) 1 : 47 : 58 to 15:3:10 of and stirring the so prepared solution continuously for 4 to 20 minutes, e) pouring carbon having acidic functional group as prepared at c) into the heated acidic solution of palladium chloride as prepared at d) of carbon to palladium chloride content of part (d) in the ratio(w/w) 60 : 1 to 17 : 5, f) reducing the above said liquid phase solution of palladium chloride by adding 4 to 65 ml of 37 % formaldehyde in the ratio (w:v) of palladium chloride to formaldehyde between 1:150 to 15 : 8 and adding 30 % aqueous solution of sodium hydroxide to make it alkaline (8 to 9 pH value) with constant stirring for 10 to 45 minutes to disperse palladium thoroughly and highly on said carbon surface,g) filtering and cooling of the above said suspension solution, h) washing the solid material obtained in step g) 8 to 20 times in water; i) drying in air at room temperature and desiccating the material in desiccator over potassium hydroxide to obtain palladium impregnated carbon, before storing it in air tight bottle for use.
Full Text FIELD OF INVENTION
This invention relates to palladium impregnated carbon for removal of carbon monoxide gas. The said palladium carbon is used for removal of carbon monoxide gas from a contaminated areas. In particular, it relates to filtration of air to make it breathable for the use of living beings. Generally carbon monoxide (CO), a haemo-toxic chemical hazard, is produced due to incomplete combustion of articles. Fires in enclosed spaces (a ship hold), and engine exhaust (particularly when rich mixtures are employed), etc., may give rise to dangerous concentration of CO gas.
The said palladium impregnated carbon works as adsorbent/catalyst for the reactive removal of carbon monoxide gas from enclosed surrounding. This carbon works as a real turn over catalyst and provides endless protection against deadly toxic carbon monoxide gas under ambient condition by oxidizing it.
BACK GROUND OF INVENTION
The subject of protection against CO gas was investigated very widely in the past. As CO gas is very light in weight, direct adsorption is apparently out of question.
Permanent bonding of CO with haemoglobin indicates that synthetic analogue of haemoglobin may be a suitable material, if it could be prepared. Direct blood is of no use.
Filters of Russian origin are currently in use in most of the countries for the removal of CO gas. These filters are very costly and provide limited protection against CO gas. These filters also do not work properly under humid conditions. Therefore, it is the need of the hour to develop adsorbent material, which can be used in filter to remove CO gas catalytically under ambient conditions.
PRIOR ART
Summary & Technical report of the National Defense Research Committee, Division 10, 1(1) 1946, Washington DC, entitled as, Military problems with aerosols and non persistent gases, by Noyes W A Jr. indicated the use of several compounds

{hoolamite (I2O5 + Fuming H2SO4), silver permanganate, Hopcalite, etc.} as a catalyst for oxidizing carbon monoxide into carbon dioxide at ambient temperature. Hopcalite predominantly comprised of copper oxide and manganese oxide was the most successful catalyst and still is in use as a universal and standard material for CO canister. Patents in which the use of hopcalite has been highlighted for the removal of CO gas are US 5,038,768 entitled as 'carbon monoxide conversion device' and US 4,925,631 entitled as 'method of casting a hopcalite filter and cast ceramic fiber-hopcalite'.
The hopcalite is a moisture sensitive catalyst and its catalytic activity is greatly reduced due to the presence of moisture in air. To save hopcalite from moisture the CO canister contains the desiccant layer/bed, which absorbs the moisture of the inlet CO contaminated air. Bigger CO filtration systems other than canister utilize the parallel air drying systems. As US 4,054,428 entitled as 'method and apparatus for removing carbon monoxide from compressed air utilizes the cyclic parallel desiccant air drying system installed upstream of the catalyst bed (hopcalite) to reduce the moisture content of the air.
The efficiency and the service life of hopcalite based canister mainly depends on the desiccant layer, i.e., as soon as the desiccant is saturated with moisture, it allows the moisture to come in contact with hopcalite layer and deactivates it. Therefore, the main disadvantage associated with hopcalite is its poisoning due to water, which makes it to be unsuitable for longer duration or under humid conditions. Yet another disadvantage of hopcalite is its lesser shelf life and limited protection against CO gas.
In last few years various catalysts based on Cu(I) Acetylacetonate complexes (US 4,279,874), gold, palladium, [J. Catal. 41 (1976) 397-404, J. Am. Chem. Soc. 123 (2001) 1166, etc.,] copper zinc oxide, and other oxides [Appl. Catal. A 295 (2) (2005) 142-149] were also prepared and their activity has been determined against CO gas. A noble metal catalyst such as platinum and palladium exhibits improved activity in the oxidation of carbon monoxide provided that the catalyst is supported by a carrier having a relatively large specific surface area such as alumina, silica, silica alumina or

diatomaceous earth. However, the level of catalytic activity is not sufficient at an ambient temperature, although it increases substantially at 50 to 70°C or higher. Palladium impregnated kaolin based adsorbent system is also available but suffers from the fact of less protection against CO gas under humid conditions. Above discussed systems also suffer from the fact that they can not be regenerated for further use.
American Institute of Chemical Engineers(AIChE) Journal Volume 42, Issue 2,1996, Pages 422-430, teaches activated carbon was impregnated with a metal halide, and adsorption and description characteristics of CO on the carbon were measured by fixed bed runs. It was found that the impregnation of PdCl2 or CuCl effectively increases CO absorption. PdCl2/CuCl impregnated carbon were characterized by N2 adsorption, SEM, EPMA, and XPS. Adsorption isotherms of CO were also measured on these carbons, and the influence of the loading of impregnate on CO adsorption was experimentally elucidated. A selection procedure of impregnate was proposed based on the frontier orbital theory. The perturbation energy for molecular orbital mixing was estimated by the HOMO-LUMO interaction. CO adsorption on impregnated carbon was qualitatively interpreted using the perturbation energy, and the energy was regarded as an index of impregnate selection.
It is evident from the above journal, the use of impregnation palladium chloride or CuCl on carbon effectively increases CO adsorption.
The present invention proposes carbon impregnated with palladium where as the prior art documents teach carbon impreganeted with palladium chloride.
OBJECTS OF THE PRESENT INVENTION
The primary objects of the invention is to prepare the adsorbent material, which remain effective under humid conditions and should not get saturated with moisture thereby becoming ineffective.

Another objects of the invention is to prepare the catalyst which is fully effective at an ambient temperature.
Another objects of the invention is to prepare the material which can be regenerated at very low cost, after it is fully exhausted.
Further objects of the invention is to prepare adsorbent material which has high shelf life.
Further objects of the invention is to prepare adsorbent/catalytic material which is made from easily and cheaply available material such as coconut shell carbon.
Another objects of the invention is to prepare cheaper adsorbent material.
Yet another objects of the invention is to prepare adsorbent material which can work in a catalytic manner to remove CO gas in any very odd situation.
DESCRIPTION OF INVENTION
The activated carbon is acidified with nitric acid to generate acidic functional groups for the synthesis of palladium impregnated carbon. The known weight of so produced acidic groups functionalized carbon is poured into the heated acidic solution of palladium chloride, followed by liquid phase reduction of palladium chloride to highly dispersed palladium on carbon surface. Reduction is performed using formaldehyde and sodium hydroxide with constant stirring. Finally the Pd/C material is filtered, washed with distilled water, dried at room temperature and finally in desiccator over the desiccant (potassium hydroxide) and stored this dried Pd/C in air tight bottles till use.
Using the same preparation method palladium impregnated carbon systems with various palladium percentages such as 4.0, 5.0, 6.0, 6.5, 8.0, are prepared.

Following is the general preparation method for Pd/C catalyst, containing 1.0-15.0 percent of palladium
In order to prepare Pd/C catalyst system containing 1.0 - 15.0 % palladium, coconut shell in the form of granular activated carbon, grade 60 to 90 Carbon Tetra Chloride (CTC) {preferably 80 CTC}, particle size 18 X 40 BSS (British Sieve Size) {preferably 12 X 30 BSS} and surface area 800 to 1500 m2/g (preferably 1250 m2/g) are taken in the ratio by weight of C: Pd = 99 : 1 to 85 :15
6.5 % of palladium impregnated on carbon surface give endless protection from atmosphere moisture and optimum result.
Initial, granular activated carbon is allowed to react with of 8 to 14% nitric acid (preferably 10 % nitric acid) in the ratio (w/v) of C : HNO3 = 1 : 4 to 1 : 6 so as to completely dipped in it at 50 to 80°C (preferably 60°C) for 5 to 10 hours, preferably 8 hours to generate acidic surface functional groups. After acid treatment, the carbon is washed with deionized water till it become neutral (pH-7). Finally it is dried in an oven at 100 to 120°C (preferably at 110°C) for 3 to 6 hours, (preferably 4 hours), cooled in desiccator and kept in air tight bottles for further processing.
Thus produced carbon is poured into distilled water in the (w/v) ratio of 1 :8 to 1: 16 and heated at 60 to 90°C for 10 to 25 minutes.
A solution of palladium chloride is produced by adding concentrated hydrochloric acid and distilled water in the ratio 1: 47 : 58 to 15 : 3 : 10 (w/v/v) and 5.0 to 25 ml of distill water is further added. The solution is continuously stirred for 4 to 20 minutes.
Carbon having acidic functional group as prepared above is poured into the heated acidic solution of palladium chloride as prepared of carbon to palladium chloride content of the solution as above in the ratio (w/w) 60 : 1 to 17 : 5.
To this, 37% formaldehyde solution is added in the ratio (w:v) of palladium chloride to formaldehyde between 1:150 to 15 : 8 and the solution is made slightly alkaline (8-

9 pH) by adding 30 % aqueous sodium hydroxide solution. The suspension is continuously stirred for 10 to 45 minutes to disperse palladium thoroughly and highly on the said carbon surface then filtering and cooling the above suspension .
Finally it is washed 8 to 20 times in water and then drying in air at room temperature and then in desiccator over potassium hydroxide, stored in air tight bottles for future use,
According to the present innovation a palladium impregnated carbon for removal of carbon monoxide gas comprises activated granular carbon with granular particle size 18 X 40 British Sieve Size (BSS), and surface area 800 to 1500 m 2/ g, and having, palladium uniformly disposed over the said carbon surface and they are in the ratio by weight of C:Pd = 99:1 to 85:15.
According to another embodiment of the present invention a process for preparation of palladium impregnated carbon for removal of carbon monoxide gas comprising of the following steps:
a) acidifying activated carbon with 8 to 14 % nitric acid in the ratio 1 : 4 to 1 :6
(w/v) at 50 to 80°C for 5 to 10 hours to generate acidic functional group over the
carbon surface,
b) washing the acidified carbon with deionized water to make it neutral (pH 7), and
drying it in an oven at 100 to 120°C preferably at 110°C for 3 to 6 hours (preferably
4 hours) followed by cooling in desiccator,
c) pouring carbon b) having acidic functional group into distilled water in the (w/v)
ratio of 1 : 8 to 1 : 16 and heating at 60 to 90°C for 10 to 25 minutes.
d) producing the acidic solution of palladium chloride by adding concentrated
hydrochloric acid and distilled water in the ratio (w/v/v) 1 : 47 : 58 to 15 : 3 : 10 of
and stirring the so prepared solution continuously for 4 to 20 minutes.
e) pouring carbon having acidic functional group as prepared at c) into the heated
acidic solution of palladium chloride as prepared at d) of carbon to palladium chloride
content of part (d) in the ratio(w/w) 60 : 1 to 17 : 5.

f) reducing the above said liquid phase solution of palladium chloride by adding
4 to 65 ml of 37 % formaldehyde in the ratio (w:v) of palladium chloride to
formaldehyde between 1 : 150 to 15 : 8 and adding 30 % aqueous solution of sodium
hydroxide to make it alkaline (8 to 9 pH value) with constant stirring for 10 to 45
minutes to disperse palladium thoroughly and highly on said carbon surface,
g) filtering and cooling of the above said suspension solution,
h) washing the solid material obtained in step g) 8 to 20 times in water; i) drying in air at room temperature and desiccating the material in desiccator over potassium hydroxide to obtain palladium impregnated carbon, before storing it in air tight bottle for use.
Preparation of 4.0 % Pd/C :-
In order to prepare 4.0 % Pd/C system, 25.0 g of acidic group functionalized carbon is poured to 300 ml of distilled water and heated 80°C for 15 minutes.
To this, a solution of 1.74 g of palladium chloride in 4.5 ml of concentrated hydrochloric acid and 15.0 ml of distill water is added. The solution is continuously stirred for 5 minutes.
To this, 16.0 ml of 37% formaldehyde solution is added and the solution is made alkaline (8-9 pH) using 30 % aqueous sodium hydroxide solution. The suspension is continuously stirred for 15 minutes.
The material is then filtered, cooled and washed 8 times with 80 ml portions of water. The material is dried in air at room temperature and then in desiccator over potassium hydroxide. Finally the material (4% Pd/C) is stored in air tight bottles till use.
Preparation of 6.5 % of Pd/C :-
In order to prepare 6.5 % Pd/C system, 25.0 g of acidic group functionalized carbon is poured to 300 ml of distilled water and heated 80°C for 15 minutes.

To this, a solution of 2.90 g of palladium chloride in 7.5 ml of concentrated hydrochloric acid and 16.0 ml of distill water is added. The solution is continuously stirred for 5 minutes.
To this, 26.0 ml of 37% formaldehyde solution is added and the solution is made alkaline (8-9 pH) using 30 % aqueous sodium hydroxide solution. The suspension is continuously stirred for 20 minutes.
The material is then filtered, cooled and washed 10 times with 100 ml portions of water. The material is dried in air at room temperature and then in desiccator over potassium hydroxide. Finally the material (6.5 % Pd/C) is stored in air tight bottles till use.
Preparation of 8..0 % of Pd/C :-
In order to prepare 8.0 % Pd/C system, 25.0 g of acidic group functionalized carbon is poured to 300 ml of distilled water and heated 80°C for 15 minutes.
To this, a solution of 3.63 g of palladium chloride in 7.5 ml of concentrated hydrochloric acid and 20.0 ml of distill water is added. The solution is continuously stirred for 10 minutes.
To this, 30.0 ml of 37% formaldehyde solution is added and the solution is made alkaline (8-9 pH) using 30 % aqueous sodium hydroxide solution. The suspension is continuously stirred for 25 minutes.
The material is then filtered, cooled and washed 15 times with 150 ml portions of water. The material is dried in air at room temperature and then in desiccator over potassium hydroxide. Finally the material (8 % Pd/C) is stored in air tight bottles till use.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 shows schematic of test rig for CO BBT studies.

Figure 2 shows mechanism of CO removal over Pd/C and regeneration of catalyst material.
Test rig for the catalytic removal of CO gas over Pd/C material catalyst
Fig 1 shows the test-rig used to generate CO-air mixture of different concentrations and to determine the efficiency of prepared Pd/C system against CO gas. For this, CO from CO cylinder (1) using ambient air pump (3) and flow meters (2) is mixed in mixing chamber (4). The concentration of CO-air mixture is determined by passing it to CO detector (8). CO-air mixture is then passed through the Pd/C column (6) using two-way control valve (5).
Effect of palladium concentration :-
In order to understand the effect of palladium on Pd/C against CO gas various adsorbent systems with different percentages of palladium content are prepared and evaluated for CO gas removal under above given experimental conditions. Table 1 describes the CO breakthrough behavior with these systems 4 % palladium impregnated carbon system could not remove CO gas completely and showed outlet concentration of 15 PPM of CO after 10 minutes, i.e., the breakthrough time is less then 10 minutes. Interesting results are that the Pd/C system does not show increase in CO concentration after 10 minutes and showed same value of outlet concentration, i.e., 15 PPM till the experiment is conducted, i.e., up to 60 minutes. 5.0 and 5.5 % of Pd/C system showed good results and can remove 97 and 98 % g of 131 PPM of CO gas respectively. However, 6.0, 6.5, and 8.0 % Pd/C system does not show any breakthrough of CO gas till the experiment is continued, i.e., up to 400 minutes. This indicates that Pd/C system containing Pd > 6.0 % is efficient for CO gas removal and to be on safer side it can be declared that 6.5 % palladium impregnated carbon catalyst is the optimized one for continuously removing CO gas under the set of giving conditions. These systems showed very high protection against CO gas under ambient conditions and are found to be working as a real turn over catalyst.
Effect of CO concentration

Table 2 describes the effect of CO concentration on breakthrough behavior with these systems. In order to increase the CO concentration and maintain the same flow rate of CO-air mixture the flow meters of CO cylinder and ambient air are adjusted accordingly. 5.0 % Pd/C system does not show good protection at double concentration of CO gas, i.e., at 262 PPM. As this system is removing 97 % of CO gas at 131 PPM but when the concentration of CO gas is doubled it can remove 90 % only and give 5 minutes as break through time (btt) value. 5.5 % Pd/C system showed promising protection at 262 PPM but can not work properly when the concentration of CO gas is increased to five times (655 PPM). The system, which is declared as optimized one (6.5 % Pd/C) shows good results at double concentration and at triple concentration (363 PPM) the outlet concentration is very near to the break through time (btt) observation value. However, this system can not work efficiently at 665 PPM. It indicates that 6.5 % palladium impregnated carbon system is the best with a factor of safety 2 under given set of experimental conditions. However, 8.0 % palladium impregnated carbon system does not show any breakthrough of CO gas even if the concentration is increased to five times, i.e., 655 PPM.
Effect of humidity
Table 3 depicts the effect of humidity on adsorption of 6.5 % Pd/C system. When the air for the dilution of CO gas is taken from an air cylinder having nil moisture contents, the breakthrough behavior of CO gas is very interesting. Up to 50 minutes outlet CO concentration is nil, at 55 minutes it is 4 PPM and at 65 minutes it is 13 PPM, i.e., breakthrough time. At 75 minutes the outlet CO concentration is 48 PPM, which indicates a fast breakthrough of CO gas. When ambient air having 55 % RH is taken for the dilution of CO gas the outlet concentration of CO gas remained nil throughout the experiment, i.e., up to 400 minutes. It highlights the necessity of moisture for the effective removal of CO gas.
In order to confirm the necessity of moisture more experiments are conducted. In order of the experiment, initially air of nil RH (air from air cylinder) is used to dilute CO gas for btt studies on Pd/C system under the given set of conditions. At 65 minutes the outlet concentration of CO gas is 13 PPM, which increased to 48 PPM at

75 minutes. Then the air cylinder is replaced with one ambient air pump. The CO outlet concentration of CO gas started coming down and within 5 minutes it reached to nil. This indicates the importance of moisture for the material to work excellently against CO gas removal.
Mechanism of reaction and regeneration
Probable mechanism for the catalyst conversation of CO to CO2 over the surface of palladium impregnated carbon system and regeneration of the catalyst material by atmospheric water is shown in Figure 2. Pd/C system initially adsorbs CO gas than it converts CO to CO2 in presence of Oxygen gas. So produced carbon dioxide gas remains on the surface of Pd/C and poisons the catalytic efficiency of the material via getting adsorbed at palladium sites. This does not allow the material to adsorb CO gas and CO breaks through very fast. If atmospheric air is used with CO gas then atmospheric water molecules regenerate the catalyst by removing the adsorbed CO2 gas molecules. In that fashion the catalyst makes (Pd/C) provides endless protection against CO gas. This quality of regeneration of the catalyst makes Pd/C system to be the best one for the removal at ambient conditions of temperature and humidity.
Shelf life study:-
In order to determine the shelf life of catalyst material (Pd/C) it is stored at 70°C and 50 % RH for 3.75 and 7.5 months, which correlate to 5 and 10 years of shelf life. After aging treatment the material is re-evaluated for its efficiency against CO gas. Table 4 represents the behavior of 6.5 % Pd/c system before and after aging @ 131 and 262 PPM of CO inlet concentration. It indicates that the material after 5 years of aging give protection @ 131 PPM and slightly down @262 PPM of CO inlet concentration. The Pd/C material after 10 years of shelf life study does not show promising results @ 131 PPM of CO inlet concentration and the outlet concentration of CO gas increased from 10 to 58 with in 200 minutes. Therefore, it indicates that the shelf life of the material (6.5 % Pd/C) at given set of experimental conditions is in between 5 to 10 years. Hence, the shelf life of the material (6.5 % of Pd/C) can be declared safely to > 5 years.

Table 1 Effect of palladium concentrations on CO breakthrough behavior.

Time (minutes) Outlet concentration of CO gas ( ppm)

4.0 % Pd 5.0 % Pd 5.5%Pd 6.0 % Pd 6.5 % Pd 8.0 % Pd
1 0 0 0 0 0 0
2 L_ 12 2 1 0 0 0
10 15 "i 0 0 0 0
25 15 4 2 0 0 0
60 15 ^i 1 0 0 0
240 — — ~ 0 0 0
400 — — — " End less protection"
Table 2 Effect of increase in CO inlet concentration on breakthrough behavior with different svstems.

Time (minutes) Outlet concentration of CO (ppm)

5.0 % 5.5%Pd 6.5 % Pd 8.0 % Pd
Pd

Inlet Inlet Inlet Inlet Inlet Inlet Inlet Inlet
CO CO CO CO CO CO CO CO
cone. cone. cone. cone. cone. cone. cone. cone.
X2 X2 X5 X2 X3 X5 X2 X5
1 4 ^i 22 1 6 20 0 0
5 24 1 47 i 10 42 0 0
12 26 1 88 i 10 78 0 0
18 26 4 85 1 12 80 0 0
60 28 : 5 88 4 12 80 0 0

Table 3 Effect of atmospheric moisture on CO breakthrough behavior with 6.5 % Pd/C.

Time (minutes) Outlet concentration (ppm) (Air from cylinder, RH ~ nil) Outlet concentration (pprn) (Ambient Air, 55 % RH)
1 0 0
50 0 0
55 4 0
65 13 0
68 24 0
70 32 0
75 48 0
400 " "Endless Protection"
Table 4 Effect of ageing and regeneration on Pd/C (Pd, 6.5% w/w) system.

Time Outlet concentration of CO (ppm)
(minutes) Before ageing After ageing - 5 After ageing- 10 Regenerated
years years Pd/C
@ 131 @ 262 @ 131 @262 @ 131 ppm CO @ 131 ppm
ppm CO ppm CO ppm CO ppm CO Inlet cone. CO Inlet
Inlet Inlet Inlet Inlet cone.
cone. cone. cone. cone.
1 0 1 0 10 10 o
5 0 3 0 7 18 0
60 0 4 0 6 38 0
200 0 -V 0 6 58 0
400 0 4 0 8 — 0


WE CLAIM
1) A palladium impregnated carbon for removal of carbon monoxide gas
comprising activated granular carbon with granular particle size 18 X 40 British Sieve
Size (BSS), and surface area 800 to 1500 m2/ g, and having palladium uniformly
disposed over the said carbon surface and they are in the ratio by weight of C: Pd =
99:1 to 85:15
2) A palladium impregnated carbon as claimed in claim 1, wherein the said
carbon is coconut shell granular activated carbon of grade 60 to 90 carbon
tetrachloride (CTC)..
3) A palladium impregnated carbon as claimed in claim 2, wherein the said
carbon grade is 80 carbon tetrachloride (CTC).
4) A palladium impregnated carbon as claimed in claim 1, wherein the said
granular particle size of carbon is 12 X 30 British Sieve Size (BSS).
5) A palladium impregnated carbon as claimed in claim 1, wherein the said
surface area of carbon is 1250 m2/g.
6) A palladium impregnated carbon as claimed in claim 1, wherein the said
percentage of palladium is 6.5 % to obtain a shelf life > 5 years
7) A palladium impregnated carbon as claimed in claim 6, wherein the said shelf
life is in the range of 5 to 10 years.
8) A process for preparation of palladium impregnated carbon for removal of
carbon monoxide gas comprising of the following steps:

a) acidifying activated carbon with 8 to 14 % nitric acid in the ratio 1 : 4 to 1 :6
(w/v) at 50 to 80°C for 5 to 10 hours to generate acidic functional group over the
carbon surface,
b) washing the acidified carbon with deionized water to make it neutral (pH 7), and
drying it in an oven at 100 to 120°C preferably at 110°C for 3 to 6 hours (preferably
4 hours) followed by cooling in desiccator,
c) pouring carbon b) having acidic functional group into distilled water in the (w/v)
ratio of 1 : 8 to 1 : 16 and heating at 60 to 90°C for 10 to 25 minutes,
d) producing the acidic solution of palladium chloride by adding concentrated
hydrochloric acid and distilled water in the ratio (w/v/v) 1 : 47 : 58 to 15 : 3 : 10 of
and stirring the so prepared solution continuously for 4 to 20 minutes,
e) pouring carbon having acidic functional group as prepared at c) into the heated
acidic solution of palladium chloride as prepared at d) of carbon to palladium chloride
content of part (d) in the ratio(w/w) 60 : 1 to 17 : 5,
f) reducing the above said liquid phase solution of palladium chloride by adding
4 to 65 ml of 37 % formaldehyde in the ratio (w:v) of palladium chloride to
formaldehyde between 1:150 to 15 : 8 and adding 30 % aqueous solution of sodium
hydroxide to make it alkaline (8 to 9 pH value) with constant stirring for 10 to 45
minutes to disperse palladium thoroughly and highly on said carbon surface,
g) filtering and cooling of the above said suspension solution,
h) washing the solid material obtained in step g) 8 to 20 times in water;
i) drying in air at room temperature and desiccating the material in desiccator over potassium hydroxide to obtain palladium impregnated carbon, before storing it in air tight bottle for use.

9) A process for preparation of palladium impregnated carbon as claimed in
claim 8, wherein nitric acid concentration is 10 %.
10) A process for preparation of palladium impregnated carbon as claimed in
claim 8, wherein heating to generate acidic surface functional groups of the carbon is
at temperature 60°C for 8 hours.
11) A process for preparation of palladium impregnated carbon as claimed in
claim 8, where in the said percentage with 6.5 % of palladium content is prepared by
adding of about 25 g of carbon having acidic functional group into 300 ml of distilled
water and heating it at 80°C for 15 minutes, and adding a solution of 2.9 g of
palladium chloride in 7.5 ml of concentrated hydraulic acid and 16 ml of distilled
water and stirring it for 5 minutes, after adding 26 .0 ml of 37 % formaldehyde
solution making this solution slightly alkaline (8-9 pH) using 30 % aqueous sodium
hydroxide solution and stirring the suspension continuously for 20 minutes, and then,
filtering the so produced material and cooling it then washing it 10 times with 100 ml
portion of water.
12) A palladium impregnated carbon for removal of carbon monoxide (CO) gas,
substantially as hereinbefore described with reference to accompanying drawings.
13) A process for preparation of palladium impregnated carbon for removal of
carbon monoxide gas substantially as hereinbefore described with reference to
accompanying drawings.

Documents:

2409-del-2006-Abstract-(11-04-2013).pdf

2409-del-2006-abstract.pdf

2409-del-2006-Claims-(11-04-2013).pdf

2409-del-2006-claims.pdf

2409-del-2006-Correspondence Others-(04-09-2008).pdf

2409-del-2006-Correspondence Others-(11-04-2013).pdf

2409-del-2006-correspondence-others.pdf

2409-del-2006-description (complete).pdf

2409-del-2006-drawings.pdf

2409-del-2006-form-1.pdf

2409-del-2006-Form-18-(04-09-2008).pdf

2409-del-2006-form-2.pdf

2409-del-2006-form-26.pdf

2409-del-2006-form-3.pdf

2409-del-2006-form-5.pdf


Patent Number 258208
Indian Patent Application Number 2409/DEL/2006
PG Journal Number 51/2013
Publication Date 20-Dec-2013
Grant Date 17-Dec-2013
Date of Filing 06-Nov-2006
Name of Patentee DIRECTOR GENERAL DEFENCE RESEARCH &DEVELOPMENT ORGANISATION
Applicant Address MINISTRY OF DEFENCE, DEFENCE R&D ORGANISATION DTE OF ER& IPR, IPR GROUP ROOM NO 348 B-WING DRDO BHAWAN,RAJAJI MARG NEW DELHI-110011 INDIA
Inventors:
# Inventor's Name Inventor's Address
1 BEER SINGH DEFENCE RESEARCH & DEVELOPMENT ESTABLISHMENT JHANSI ROAD,GWALIOR,MADHYAPRADESH INDIA
2 AMIT SAXENA DEFENCE RESEARCH & DEVELOPMENT ESTABLISHMENT JHANSI ROAD,GWALIOR,MADHYAPRADESH INDIA
3 KRISHNAMURTHY SEKHAR DEFENCE RESEARCH & DEVELOPMENT ESTABLISHMENT JHANSI ROAD,GWALIOR,MADHYAPRADESH INDIA
PCT International Classification Number B01J23/44; B01J23/44
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA