CA2048263A1

CA2048263A1 - Process for helium purification

Info

Publication number: CA2048263A1
Application number: CA002048263A
Authority: CA
Inventors: Ramachandran Krishnamurthy; Satish S. Tamhankar; Walter H. Whitlock
Original assignee: BOC Group Inc
Current assignee: Messer LLC
Priority date: 1990-08-23
Filing date: 1991-08-01
Publication date: 1992-02-24
Also published as: ZA915939B; KR920004276A; PL291486A1; KR940004626B1; PL168674B1; JPH04250815A; DE4125538A1; DE4125538C2

Abstract

A process for extracting helium from a feedstock containing helium at moderate levels together with trace amounts of hydrogen is disclosed. Helium is separated from the feedstock by pressure swing adsorption (PSA) and the hydrogen impurity is removed by chemisorption in a nickelbased catalytic bed. Where the feedstock contains significant amounts of nitrogen, less than 5% methane, and less than 1000 ppm carbon dioxide, the catalytic step preferably precedes the PSA step. Regeneration of the catalytic bed is preferred by passing over the spent bed an inert gas with controlled amounts of an oxidizing agent, preferably oxygen, to react with adsorbed hydrogen to form water. This method substantially increases the catalyst's capacity to adsorb hydrogen when the catalytic unit is placed back in service and eliminates the conventional step of thermally regenerating the bed by heating with an inert gas for an extended period of time.

Description

I: 9521003 073 00: ek PROCESS FOR HELIUM PURIFICATION
Fled f the Invention This invention relates to the puxification of helium and particularly to a method of refining helium through complete removal of hydrogen impurity by catalysis and complete methane and partial or complete nitrogen removal by pressure swing adsorption (PSA).
Description of Prior Art As demand for helium grows with technological innovation, alternative cost-effective means for producing helium become increasingly important. Efficient processes are needed to handle feeds containing a variety of impurities including hydrogen. Hydrogen is a difficult component to remove from helium through traditional helium purification methods of cryogenic distillation and PSA because ox the close similarity between the physical properties of hydrogen and helium.
uch of the prior art of helium puxification has been concerned with recovery of helium using combined cryogenic and PSA processes. U.S. Patent No ~,701,200, for example, discloses a process whereby an enriched helium stream, typically 85~92% helium, is recovered as a byproduct from the cryogenic separation of a process stream containing helium admixed with methane and nitrogen into its primary components of methane and nitrogen. The enriched helium stream is removed from the cryogenic section, warmed to ambient temperature, and purified in a PSA unit Similarly, in U.S. Patent No. 4,659,351, a crude helium stream containing approximately 50% helium, is enriched at cryogenic temperatures through use of flash separators. The enriched helium is warmed to ambient condition where it is further purified by PSA. While these processes yield pure helium (<lOppm N2 and other impurities)l they are very costly due to special equipment, materials, and insulation requirecl for cryogenic processing. Additionally, the disclosures do not mention the effectiveness in removing hydrogen impurity prom helium, which is known to be difficult through cryogenic and/or PSA processing.
Helium purification by PSA without cryogenic processing from a stream containing nitrogen, methane, and helium is knownr German Patent DE 3,716,899 discloses a two-step carton molecular sieve PSA arrangement in which a 5%
helium feed stream is enriched to 79.5% after the first stage and to 99.9% after the second stage. A prepurification stage is also disclosed to remove trace amounts of higher hydrocarbons (C2+), but its effectiveness for hydrogen removal is not disclosed. A practical disadvantage of this process is the high operating pressures (approx. 300 psia) and the high vacuum levels of 50 millibars ~<1.0 PSI) required to achieve Lo .3 !
desired purity and recovery. The second stage PSA operates at low helium recovery as a portion of the product helium is used as a purge gas additionally, a power penalty i5 incurred when the second stage vent gas i5 recompressed to the high adsorption pressure in an effort to reduce helium losses.
Finally, buffer vessels are required to maintain Gontinuity in process flows because the two PSA stages oplerate at widely different cycle times.
An object of the present invention is to provide a method of helium purification from a stream containing impurities of methane, nitrogen and hydrogen.
Another object of the present invention is to provide a method of helium purification from a stream containing impurities of methane, nitrogen and hydrogen by pressure swing adsorption (PSA) and catalysis.
A further object of the present invention is to provide a method of helium purification from a stream containing impurities of methane, nitrogen and hydrogen at substantially ambient temperatures to avoid use of costly cryogenic equipment.
Another object of the present invention is to provide a methocl of helium purification from a stream containing impurities of methane, nitrogen and hydrogen at moderate pressure to lessen power consumption.
Still another object of this invention is to remove the hydrogen impurity my using a nickel-based catalyst and regenerate the catalytic bed with controlled amounts of oxygen to substantially increase capacity of the catalyst to remove hydrogen and eliminate the conventional thermal regeneration step.
Summary of the Invention Now in accordance with the present invention, a process is disclosed for separating helium from a feedstock containing trace amounts of hydrogen in a two-step noncryogenic process. Pursuant to the invention helium is eparated from the feedstock by pressure swing adsorption (PSA), and the hydrogen impurity is removed in a catalytic bed, preferably by using a nickel-based catalyst. While the catalytic removal step will generally follow the PS~ step, it may usefully precede PSA where the feedstock is one containing significant amounts of nitrogen, less than 5% methane, and loss than 1000 ppm C02. Although the individual steps of pressure swing adsorption (PSA) and catalytic removal of hydrogen are well known to those skilled in the art, their combination and unique modification in this invention can readily yield a helium recovery exceeding 95% and a helium purity exceeding 99.99% if desired. Additionally, purification of helium occurs at ambient temperatures and at moderate pressures in the range of ~5 to 150 psia; these are desirable conditions and the pressure levels are significantly lower than pressures disclosed in prior art.
In practice of the invention, a feedstock containing 6-40% helium, nominally less than 1000 ppm hydrogen and the remainder o methane, nitrogen, argon, higher hydro-carbons, carbon dioxide, and water vapor, is joined with a secondary product recycle stream and compressed to about 75 ;,i~L~

psia. In the preferred embodiment, the process stream enters a PSA unit where all of thy impurities except hydrogen are removed. The secondary product recycle stream is withdrawn from an intermediate position in the PSA unit in order to prevent nitrogen contamination of the helium product while providing the ability to recover most of thle helium present in the bed void which wsuld otherwise be lost upon regeneration of the bed. The effluent from the PSA next enters the catalytic Ted wherein the hydrogen is removed.
The catalytic removal of hydrogen can be accomplished by one of several known methods. In one method, the hydrogen containing helium stream is passed over a palladium catalyst (Pd/~12O3) bed after the addition of a controlled amount of oxygen. The oxygen combines with hydrogen to form water. The water is subseguently removed by an additional drying step. If the concentration of hydrogen in the helium stream varies, it is difficult to control the amount of o~yg~n to be added. In a second method, the hydrogen containing helium stream is heated to a tPmperature of approximately 400F and passed over a copper oxide catalyst maintained at the high temperature. The hydrogen reacts with the catalyst to form water. The water, again has to be removed from the helium stream in a subsequent drying step.
Additionally, in this case a heat exchanger will be needed to cool the gas before the drying step. A third and preferred method for removing hydrogen from the helium stream is thy use of a nickel-based catalyst. The advantages of using a nickel-based catalyst in helium purification compared to the more commonly employed palladium and copper oxide catalysts include: (1) nickel catalyst removes hydrogen by chemisorption (alternatively referred to as adsorption or catalytic reaction) in the absence of oxygen, thereby avoiding the need to add controlled amounts of oxygen in the process;

(2) the hydrogen chemisorption on nickel catalyst takes place at ambient temperature; (3) water iB not formed during the hydrogen chemisorption on the nickel catalyst and thereby a drying step i5 not required; (4~ any C2 or water present in the helium stream is also simultaneously removed by the nickel catalyst; and (5) the capacity of the nickel catalyst can be significantly enhanced by using a novel regeneration procedure discussed below.
A conventional method of regenerating a nickel-based catalyst is the use of a countercurrent hot purge. However, since nickel has a high affinity for hydrogen, substantial amounts of hydrogen still remain on the catalyst after a hot purge. Therefore, it is preferred in accordance with thy present invention, that regeneration of the catalytic bud be accomplished by passing a nitrogen inert gas stream containing controlled amounts of oxygen, preferably about 1000 vpm. This method of regeneration 6ubstantially increases the capacity of the catalyst for hydrogen removal and eliminates the thermal regeneration step conventionally used to desorb the hydrogen prom the catalyst. However, after completion of the above step, the bed is heated for a short period of time to about 200C by a flowing inert gas stream to drive off the moisture formed from the reaction of hydrogen with oxygen.

3~.

In the alternative embodiment, khe catalytic step precedes the PSA step. As mentioned above, this variation is preferred when the feedstock contains substantial amounts of nitrogen, less than 5% methane, and less than 1000 ppm carbon dioxide. The advantage of this arrangement i5 that the effluent from the PSA unit is mostly hydrogen-free nitrogen, which may be used to eliminate or at least lessen external nitrogen requirements needed to regenerate the catalytic bed.
Brief Description of Drawinas In the drawings appended hereto:
Figure 1 is a schematic block diagram of the preferred embodiment of this invention; and Figure 2 is a detailed schematic depicting thP
pressure swing adsorption section of this invention; and Figure 3 is a schematic block diagram of the catalytic unit section of this invention; and Figure is a schematic block diagram of an alternate embodiment of this invention.
Detailed Description of the Invention The process scheme of the present invention is depicted in Figure 1. Feed stream 1 at ambient conditions is compressed to about 75 psia at compressor 100. The composition of the feed stream is unusual in that it contains high levels of helium and trace amounts of hydrogen. Prior art has not disclosed processes concerned with such concentrations. Feed concentrations normally range 6-~0~
helium, typically 25%; 10-50% nitrogen, typically 20%; 25-60%
methane, typically 50~; 1-3% water, typically 3~; 0-0.6%

,~3~

argon, typically 0.5~; 0-1000 ppm higher hydrocarbons (C2+~, typically 100 ppm; 0 1000 ppm carbon dioxide, typically 100 ppm; and 0-1000 ppm hydrogen, typically 100 ppm. The secondary helium recycle stream l used to minimize helium losses due to the gas in the bed void Gpace and ths gas weakly bound to the adsorbent, and to control nitrogen contamination in the helium product, is combined with feled stream 1 before compression. Compressor outlet 3 is cooled by an aftercooler 2~0 in which water condensate 4 is removed.
Process stream 5 enters the PSA purification unit 300 whereat a zeolite molecular sieve selectively adsorbs carbon dioxide, methane and nitrogen. Commercially available type 5A molecular sieve is appropriate for this type of applicat.ion, but zeolites such as lOX, 13X or mordenites can also be used. Helium and hydrogen are not adsorbed and pass through the bed. The adsorbed components are released as waste gas 10 during vacuum regeneration.
Activated carbon may be used as an alternative adsorbent to zeolite molecular sieve. Carbon molecular sieve, which selectively removes methane, can be combined with the zeolite or activated carbon. Additionally, for high water content in the feed, a small layer of alumina is placed at the feed end of the PSA beds to remove water For significant amounts of higher hydrocarbons (C2+) in the feed, a layer of ilica gel adsorbent is placed at the feed end.
Figure 2 depicts the arrangement of the preferred secondary product recycle seguence and Table 1 indicates the valve positions for the various sequence steps.

i,'J ~j~ U

Four Bed Helium PSA Cycle Sconce STEP TIME BED A BED B BED C BED D
1 30 FEED PROD. BPE (REPRES) VAC. ~EGEN. BPE (DEPRES) 2 150 FEED PROD. REPRES. VAC. REGEN. SEC. PRODUCT
3 30 BPE (DEPRES) FEED + PROD. BPE (REPRES) VAC. REGEN.

4 150 SEC. PRODUCT FEED + PROD. REPRES. VAC. REGEN.
VAC. REGEN. BPE ~DEPRES) FEED + PROD. BPE (REPRES) 6 150 VAC. REGEN. SEC. PRODUCT FEED + PROD. REPRES.
7 30 BPE (REPRES) SAC. REGEN. BPE (DFPRES) FEED PROD.
8 150 REP~ES. VAC. REGEN. SEC. PRODUCT FEED t PROD.
l~:Y:
FEED + POD. : Feed gas admitted to the bottom of the ads~rber. Helium rich product released from the top.
BPE (DEPRES) : Bed pressure equalized to another bed at lower pressure. Equalization is through top and bottom ends.
SEC. PRODUCT : Bed depressurized from the intermediate location. Secondary product gas collected in a buffer vessel, compressed and recycled to feed gas.
VAC. ~EGEN. : Bed opened to vacuum pump suction through the bottom end to remove CH4/N2 rich gas.
BPE (REPRES) : Bed pressure equalized with another bed at higher pressure.
REPRES. : Repressurization to adsorption pressure using helium rich product gas from the PSA.
~ALVE~ OPEN:
STEP #
1 301, 305, 310, 314, 312, 316, 319 2 301, 305, 319, 322, 328 3 302, 306, 309, 313, 311, 315, 32 4 302, 3n6, 320, 323, 325 303, 307, 310, 314, 312, 316, 317 6 303, 307, 317, 324, 326 7 304, 308, 309, 313, 311, 315, 31 8 304, 3~8, 318, 321, 327 t~J 1 The significance of Table l's sequence is to simultaneously minimize helium losses and minimize nitrogen contamination of the helium product. After pressure equalization is achieved for a particular bed, the bed is depressurized from an intermediate location and the effluent ~-tream of helium, nitrogen, and small amounts of methane is recycled to the feed. The intermediate location is depicted in Figure 2 as the stream which is withdrawn between the two discrete sections of each bed. For example, bed 360 is divided into sections 361 and 362. These discrete sections need not be separate vessels and can be different layers in the same vessel with a port located at the appropriate level on the bed. Selection of the appropriate pressure at the end of the secondary product removal step insures that only a small amount of helium i5 present in the bed which minimizes helium loss when the bed is regenerated under vacuum.
The mechanics of PSA regeneration and secondary product recycle are described below. Bed 360 is selected as reference for one complete cycle. The sequence for the remaining beds, 370, 380, and 390 are identical.
During step 1, feed gas enters bed 360 through valve 301. impurities are adsorbed and helium product along with trace guantities of hydrogen leave bed 360 through valve 305.
Pressure for bed 3S0 is controlled by pressure control valve 35~. Helium product is released when bed 360' 8 pressure is above the v~lv~ 350'~ jet point pressure. If the feed compressor's discharge exceeds the jet pressure of pressure control valve 104, a portion of the compressor discharge is recycled to the 6uction of the compressor through the secondary product buffer tan.
tep 2 of the sequence is completed when nitrogen reaches the product end of bed 360 and ales 301 and 30S are closed. During step 3, ~alva~ 309 end 3~3 are open and gas enters bed 380 through valves 311 and 315 respectively. 8tep 3 it a pressure equalization step wherein Ted 360 is depressurized to an intermediate pressure and bed 38Q is partially pressurized. At the end of ~t¢p 3, vies 3a9 and 313 are closed and valve 325 is opened to commence secondary product recycle. Bed 360 depressurizes into the secondary product buffer tank 3~0 until the set pressure of pressure control valve 330 is reached.
tep 4 releases the secondary product to the suction of the feed gas compressor 100. During 8tep 5, ~21ve 317 is opened and bed 360 is evacuated by the vacuum pump 500. The gas released during this step contains the impurities of methane and nitrogPn which were adsorbed by the bed. This gas may accumulate in an optional buffer tank in the waste gas manifold. Pressure control valve 520 controls the pressure at which waste gas is removed.
Vacuum regeneration of bed 360 is continued through 8tep 6. During step 7, Ted 360 undergoes a pressure equalization step with bed 380 to partially repressurize bed 360. 5tep 8 insures that bed 360 is fully repressurized to a pressure near the desired adsorption pressure. This repressurization step is accomplished by allowing a small portion of the helium product to enter bed 360 through 3',~

repressurization flow controller 355 and ~alv~ 321. Upon completion of step 8, bed 360 is at or near the desired adsorption pressure and ready to repeat the cycle of operations.
PSA regenPration i5 at vacuum in the range of 1-5 psia, typically 2 psia. For high helium recovery, vacuum regeneration is preferred over product purge as helium losses are minimized. In the pr~ferrsd embodiment of the present invention any minute oxygen leakage into the system will not be of consequence, as toe oxygen will be removed in the catalytic step. As mentioned earlier, the secondary product recovery stream 11, which is recycled with the fresh feed 1, is removed from an intermediate location in the PSA bed to recover a major portion of the helium in the PSA bed void to increase helium recovery. Additionally, the secondary product is removed from an intermediate position in the bed so that the high nitrogen content in this product does not contaminate the primary helium product.
Referring to Figure 1, the helium rich stream 8 exits the PSA unit 300 and enters the catalytic unit ~00 containing less than 1 ppm each of carbon dioxide and methane, and the desired amount of nitrogen depending on whether complete or partial removal of nitrogen is required. The catalytic removal of hydrogen of the present invention is based on a prior invention for purification of inert gases which is sully disclosed in U.S. Patent No. 4,713,224, assigned to the assignee of the instant application. however, this patent did not include helium as an inert gas. eased on this patent disclosure, a nickel-based catalyst, preferably Harshaw catalyst Ni-0104, is used to retain the hydrogen impurity by chemisorption. Chemisorption is achieved at ambient temperatures without need of heating or cooling the catalyst. The effluent helium product contains no more than 1 ppm of hydrogen, most likely less than 0.1 ppm. The nickel-based catalyst also removes carbon dioxide and water impurities if present.
Regeneration of the nickel-based catalytic bed ~00 is accomplished by passing a regenerative gas 6 over the spent catalyst and removing the regenerative gas containing desorbed hydrogen as stream 7. Two schemes exist for regeneration of the catalytic bed. The conventional method is by thermal regeneration whereby an inert gas stream i6 heated to about 200C and introduced countercurrently to the normal process gas flow. This hot purge is continued for a predetermined length of time after which the catalyst bed is cooled to ambient.
The preferred method of the nickel-based catalyst regeneration is based on a novel procedure which substantially increases capacity of the catalyst for hydrogen removal. The nickel catalyst has a very high affinity for hydrogen and conventional thermal regeneration is inadequate to remove the substantial amounts of hydrogen which remain. By introducing controlled amounts of oxygen into such a bed, a reaction with the hydrogen forms water.
The steps of the regeneration sequence are best described by referring to Figure 3, a schematic block diagram of the catalytic system which shQws two catalytic beds ~30 and ~0. Two catalytic beds are preferred because cyclic operation of each bed allows for continuous purification of the helium stream. In the following discussion, bed 440 will be described in its helium purification mode while bed 430 will be described in its regenerative mode.
According to Figure 3, helium containing trace quantities of hydrogen enters the catalytic system through stream 8 and enters bed ~40 through valve ~19. Purified helium product exits bed 440 through valve 421 where it enters the helium product line 9. Valves 418 and ~20 remain closed to prevent the helium from entering bed 430 which is regenerating. Likewise, valves ~14 and ~16 remain closed to prevent the regenerative gas mixture from entering bed i40.
The regenerative gas mixture 6 contains an inert gas/ preferably nitrogen, and controlled quantities of oxygen which are introduced into the inert gas through line 401. The quantity of oxygen mixed into the inert gas is precisely controlled by valve 412 such that the regenerative gas mixture contains no more than about 5000 vpm oxygen, preferably about 1000 ~pm. The regenerative gas mixture enters bed 430 through valve 413 and exits through valve 415.
At a predetermined time, the oxygen supply is discontinued by closing valve ~11 and the bed is heated to about 200C by a flowing inert gas stream preferably nitrogen.
This heated inert gas stream inters and exits the catalytic unit by the same path as the regenerative gas mixture described above carrying away moisture. The inert gas flow is ;J~,/i 3 :/J

maintained for a predetermined time to drive off the moisture.
After the catalyst is cooled to room temperature, a portion of the pure helium product is used to remove the inert gas in the bed, if such gas is not helium.
The alternate process scheme for the present invention, where the catalytic unit 400 precedes the PSA unit 300, is depicted in Figure 4. This scheme is preferred to treat feed streams containing less than 5% methane, less than 1000 ppm carbon dioxide, and significant amounts of nitrogen.
Since the waste gas ~0 from the PSA is essentially hydrogen-free nitrogen in this arrangement, it may be used as regeneration gas 6 for the catalytic unit thereby eliminating much, if not all, of the external nitrogen supply requirements. In this arrangement, the exiting stream 8 from the PSA unit 300 contains hydrogen-free helium product.
Several modifications to PSA separation or PSA cycle variations are possible, and these are to be recognized as within the scope of this invention. Thus, use of PSA for partial methane or partial nitrogen removal integrated with cryogenic purification or modification of the PSA cycle to separate the feedstock into nitrogen-rich or methane-rich product fractions with subseguent purification are also to be recognized.
While the present invention has thus been particularly jet forth in terms of specific embodiments thereof, it will be understood in view of the instant disclosure, that numerous variations upon the invention are now enabled to those skilled in thP art, which variations yet reside within the scope of the present teaching. Accordingly the invention is to be broadly construed and limited only by the scope and spirit of the claims now appended here to .

Claims

WHAT IS CLAIMED IS:

1. A process for extracting helium from a feed-stock containing helium at moderate levels together with trace amounts of hydrogen comprising:
a) separating said helium from said feedstock by pressure swing adsorption (PSA); and b) separating said hydrogen impurity in a catalytic bed.

2. A process in accordance with claim 1 wherein said PSA step precedes said catalytic step.

3. A process in accordance with claim 1 wherein said feedstock contains significant amounts of nitrogen, less than 5% methane, and less than 1000 ppm carbon dioxide; and wherein said catalytic step precedes said PSA step.

4. A process in accordance with claim 1, wherein said feedstock includes a mixture of helium, nitrogen, methane, water vapor, argon, higher hydrocarbons, and hydrogen.

5. A process in accordance with claim 1, wherein said moderate level of helium in said feedstock is in the range of 6 to 40% helium.

6. A process in accordance with claim 1, wherein said trace amount of hydrogen is less than 1000 ppm.

7. A process in accordance with claim 1, wherein said PSA cycle comprises passing said feedstock through the PSA unit at an adsorption pressure in the range of 25 to 150 psia and at substantially ambient temperatures.

8. A process in accordance with claim 1, wherein said catalytic step employs a nickel-based catalyst.

9. A process in accordance with claim 1, wherein said PSA cycle utilizes a secondary product recovery stream to minimize helium losses and maintain helium product purity.

10. A process in accordance with claim 1, wherein purified helium product contains less than 1 vpm hydrogen.

11. A process in accordance with claim 2, wherein said feedstock includes a mixture of helium, nitrogen, methane, water vapor, argon, higher hydrocarbons, and hydrogen.

12. A process in accordance with claim 2, wherein said moderate level of helium in said feedstock is in the range of 6 to 40% helium.

13. A process in accordance with claim 2, wherein said trace amount of hydrogen is less than 1000 ppm.

14. A process in accordance with claim 2, wherein said PSA cycle comprises passing said feedstock through the PSA unit at an adsorption pressure in the range of 25 to 150 psia and at substantially ambient temperatures.

15. A process in accordance with claim 2, wherein said catalytic step employs a nickel-based catalyst.

16. A process in accordance with claim 2, wherein said PSA cycle utilizes a secondary product recovery stream to minimize helium losses and maintain helium product purity.

17. A process in accordance with claim 2, wherein purified helium product contains less than 1 vpm hydrogen.

18. A process in accordance with claim 3, wherein said feedstock includes a mixture of helium, nitrogen, methane, water vapor, argon, higher hydrocarbons, and hydrogen.

19. A process in accordance with claim 3, wherein said moderate level of helium in said feedstock is in the range of 6 to 40% helium.

20. A process in accordance with claim 3, wherein said trace amount of hydrogen is less than 1000 ppm.

21. A process in accordance with claim 3, wherein said catalytic step employs a nickel-based catalyst.

22. A process in accordance with claim 3, wherein said PSA cycle utilizes a secondary product recovery stream to minimize helium losses and maintain helium product purity.

23. A process in accordance with claim 3, wherein purified helium product contains less than 1 vpm hydrogen.

24. A process for regeneration of a nickel-based catalytic bed containing adsorbed hydrogen comprising:
a) passing a regenerative mixture of an inert gas and a controlled amount of oxidizing agent over the spent nickel-based catalytic bed at substantially ambient conditions;
b) continuing said regenerative gas mixture for a period of time necessary to free said nickel-based catalytic bed of chemisorbed hydrogen;
c) passing a heated inert gas stream at about 200°C
for a period of time necessary to drive off moisture formed by the reaction of hydrogen with the oxidizing agent; and d) cooling said nickel-based catalytic bed with an inert gas for a period of time sufficient to return it to ambient temperature.

25. A process in accordance with claim 24, wherein said inert gas is one or more of argon, nitrogen or helium, and said oxidizing agent is oxygen.

26. A process in accordance with claim 24, wherein aid controlled amount of oxygen is no greater than about 5000 vpm oxygen.

27. A process in accordance with claim 1, wherein said catalytic bed employs a nickel-based catalyst, and further including periodically regenerating said nickel-based catalytic bed.

28. A process in accordance with claim 2, wherein said catalytic bed employs a nickel-based catalyst, and further including periodically regenerating said nickel-based catalytic bed.

29. A process in accordance with claim 3, wherein said catalytic bed employs a nickel-based catalyst, and further including periodically regenerating said nickel-based catalytic bed.

30. A process in accordance with claim 27, wherein said nickel-based catalytic bed is periodically regenerated by:
a) passing a regenerative mixture of an inert gas and a controlled amount of oxidizing agent over the spent nickel-based catalytic bed at substantially ambient conditions;

b) continuing said regenerative gas mixture for a period of time necessary to free said nickel-based catalytic bed of chemisorbed hydrogen;
c) passing a heated inert gas stream at about 200°C
for a period of time necessary ti drive off moisture formed by the reaction of hydrogen with the oxidizing agent; and d) cooling said nickel-based catalytic bed with an inert gas for a period of time sufficient to return it to ambient temperature.

31. A process in accordance with claim 28, wherein said nickel-based catalytic bed is periodically regenerated by:
a) passing a regenerative mixture of an inert gas and a controlled amount of oxidizing agent over the spent nickel-based catalytic bed at substantially ambient conditions;
b) continuing said regenerative gas mixture for a period of time necessary to free said nickel-based catalytic bed of chemisorbed hydrogen;
c) passing a heated inert gas stream at about 200°C
for a period of time necessary to drive off moisture formed by the reaction of hydrogen with the oxidizing agent; and d) cooling said nickel-based catalytic bed with an inert gas for a period of time sufficient to return it to ambient temperature.

32. A process in accordance with claim 29, wherein said nickel-based catalytic bed is periodically regenerated by:

a) passing a regenerative mixture of an inert gas and a controlled amount of oxidizing agent over the spent nickel-based catalytic bed at substantially ambient conditions;
b) continuing said regenerative gas mixture for a period of time necessary to free said nickel-based catalytic bed of chemisorbed hydrogen;
c) passing a heated inert gas stream at about 200°C
for a period of time necessary to drive off moisture formed by the reaction of hydrogen with the oxidizing agent; and d) cooling said nickel-based catalytic bed with an inert gas for a period of time sufficient to return it to ambient temperature.

33. In the process for purifying helium contained in a feedstock including trace quantities of hydrogen as an impurity, the method for separating said hydrogen, comprising:
passing said feedstock over a nickel-based catalytic bed, whereby said hydrogen is chemisorbed upon said catalyst.

34. A method in accordance with claim 33 wherein said nickel-based catalytic bed is operated at substantially ambient temperature.

35. A process in accordance with claim 33, wherein said nickel-based catalytic bed is periodically regenerated by:
a) passing a regenerative mixture of an inert gas and a controlled amount of oxidizing agent over the spent nickel-based catalytic bed at substantially ambient conditions;

b) continuing said regenerative gas mixture for a period of time necessary to free said bed of chemisorbed hydrogen;
c) passing a heated inert gas stream at about 200°C
for a period of time necessary to drive off moisture formed by the reaction of hydrogen with the oxidizing agent; and d) cooling said nickel-based catalytic bed with an inert gas for a period of time sufficient to return it to ambient temperature.