Hydrogen purification

Claim 2

The pressure swing adsorption method of purifying an impure hydrogen gas stream containing a dilute contaminant of CH 4 which method comprises: passing said stream at superatmospheric pressure through an adsorbent bed of a zeolite obtained by replacing at least a portion of the sodium cation of sodium X-zeolite by barium ions to absorb said CH 4 contaminant and recovering purified hydrogen as unsorbed effluent, depressurizing the adsorbent bed, purging the adsorbent bed with product hydrogen and repressurizing the adsorbent bed with product hydrogen.

Claim 3

The method as defined in claim 1 wherein said zeolite is one obtained by replacing 60-80% of the sodium cation of said sodium X zeolite by barium ions.

Claim 4

The method as defined in claim 1 wherein said impure hydrogen gas stream is that obtained by first subjecting a crude hydrogen stream from hydrocarbon reforming to bulk separation to remove contained water vapor and carbon dioxide.

Claim 5

The method as defined in claim 1 wherein said zeolite is one having 0-40% sodium cation and up to 100% of barium cation.

Claim 6

The method as defined in claim 1 wherein said zeolite is one having approximately 30% to 40% strontium cation and up to 70% barium cation.

Claim 7

The method as defined in claim 1 wherein said impure hydrogen gas stream is that obtained by subjecting a carbon monoxide-containing hydrogen gas stream to a shift reaction to convert the carbon monoxide to the dioxide and treating the product of said shift reaction for removal of contained carbon dioxide therefrom.

Claim 8

The pressure swing adsorption method for separation and recovery of high purity hydrogen from a crude hydrogen gas stream containing water vapor and carbon dioxide as the principal impurities and a dilute amount of methane, which comprises the steps of: (a) passing said crude hydrogen stream at superatmospheric pressure through a first bed comprised of solid adsorbent, thereby removing contained carbon dioxide and water vapor; (b) then passing the effluent from said first bed through a second adsorbent bed comprised of a barium X-zeolite and discharging from said second bed unadsorbed hydrogen at high purity, said passing being continued for a controlled time period until or short of breakthrough of carbon dioxide from said first bed; (c) rinsing said first bed by flowing a stream of substantially pure carbon dioxide therethrough at substantially initial feed pressure level and for a controlled time period effective to purge most of the void and displaced gases from said first bed followed by pressure reduction and evacuation of the rinsed first bed; (d) reducing the pressure in the second bed by gas withdrawal to near ambient pressure level and rinsing said second bed with high purity hydrogen; (e) then restoring both said beds to initial superatomspheric pressure level by admission of substantially pure hydrogen thereto.

Claim 9

The pressure swing adsorption method for separation and recovery of high purity hydrogen from a crude hydrogen gas stream containing water vapor and carbon dioxide as the principal impurities and a dilute amount of methane, which comprises the steps of: (a) passing said crude hydrogen stream at superatmospheric pressure through a first bed comprised of solid adsorbent, thereby removing contained carbon dioxide and water vapor; (b) then passing the effluent from said first bed through a second adsorbent bed comprised of a barium X-zeolite and discharging from said second bed unadsorbed hydrogen at high purity, said passing being continued for a controlled time period until or short of breakthrough of carbon dioxide from said first bed; (c) rinsing said first bed by flowing a stream of substantially pure carbon dioxide therethrough at substantially initial feed pressure level and for a controlled time period effective to purge most of the void and displaced gases from said first bed followed by pressure reduction and evacuation of the rinsed first bed; (d) reducing the pressure in the second bed by gas withdrawal to near ambient pressure level and rinsing said second bed with high purity hydrogen; (e) then restoring both said beds to initial superatomspheric pressure level by admission of substantially pure hydrogen thereto.

Claim 10

The method as defined in claim 7 wherein said barium X-zeolite corresponds to that in which the cationic component comprises 0 to 40% Na and 60-100% of an alkaline earth cation of barium in admixture with strontium.

Claim 11

The method as defined in claim 7 wherein said barium X zeolite corresponds to that in which the cationic component comprises 0 to 40% Na and 60-100% of Ba cation.