Removal of hydrogen and carbon monoxide impurities from gas streams
Hydrogen and carbon monoxide impurities are removed from a dry gas comprising the impurities, wherein the dry gas is at least substantially free of carbon dioxide, by passing the dry gas with sufficient residence time, e.g. at least 1.5 s, through a layer of catalyst comprising a mixture of manganese oxide and copper oxide. The use of expensive noble metal catalysts to remove hydrogen may thereby be avoided. In addition, regeneration of the catalyst using oxygen-containing regeneration gas does not reduce the effectiveness of the catalyst.
1. A process for removing hydrogen and carbon monoxide impurities from a dry gas comprising said impurities, wherein said dry gas is at least substantially free of carbon dioxide, said process comprising passing said dry gas through a layer of catalyst comprising a mixture of manganese oxide and copper oxide, with sufficient residence time to produce product gas exiting the layer of catalyst comprising the mixture of manganese oxide and copper oxide that is at least substantially free of hydrogen and carbon monoxide, wherein the residence time within the catalyst layer is at least 1.5 s.
2. The process according to claim 1 , wherein the layer of catalyst comprises from 30 to 60 wt % manganese and from 10 to 30 wt % copper (based on total atomic mass).
3. The process according to claim 1 , wherein the layer of catalyst is hopcalite.
4. The process according to claim 1 , wherein the dry gas comprises up to about 20 ppm hydrogen.
5. The process according to claim 1 , wherein the dry gas comprises up to about 50 ppm carbon monoxide.
6. The process according to claim 1 , wherein the dry gas contains no more than about 10 ppm water.
7. The process according to claim 1 , wherein the dry gas contains no more than about 10 ppm carbon dioxide.
8. The process according to claim 1 , wherein oxygen is present in the dry gas in an amount from about 1 mol. % to about 50 mol. %.
9. The process according to claim 1 , wherein the dry gas is air.
10. The process according to claim 1 , wherein the dry gas is passed through the layer of catalyst at a pressure from about 3 bar to about 25 bar (0.3 MPa to 2.5 MPa).
11. The process according to claim 1 , wherein the dry gas is at a temperature from about 0° C. to about 60° C.
12. The process according to claim 1 , wherein the product gas comprises no more than 10 ppb carbon monoxide.
13. The process according to claim 1 , wherein the product gas comprises no more than 10 ppb hydrogen.
14. The process according to claim 1 , wherein the layer of catalyst is regenerated by passing a regeneration gas at a temperature of at least 180° C. through the layer of catalyst for at least 25 minutes.
15. The process according to claim 14 , wherein the regeneration gas comprises oxygen to supply oxygen to the layer of catalyst surface.
16. A process for removing hydrogen and carbon monoxide impurities from a dry air comprising said impurities, wherein said dry air is at least substantially free of carbon dioxide, said process comprising passing said dry air at a pressure from about 3 bar to about 25 bar (0.3 MPa to 2.5 MPa) and at a temperature from about 0° C. to about 60° C. through a layer of hopcalite catalyst with a residence time within the catalyst layer of at least 1.5 s to produce product gas exiting the layer of hopcalite catalyst that is at least substantially free of hydrogen and carbon monoxide.
17. An adsorption unit for removing water, carbon dioxide, hydrogen and carbon monoxide impurities from a gas comprising said impurities, said unit comprising an adsorbent bed, said adsorbent bed consisting of:
at least one adsorbent layer for removing water and carbon dioxide from said gas to produce dry gas that is substantially free of carbon dioxide;
a layer of catalyst for removing hydrogen and carbon monoxide impurities from said dry gas to produce product gas that is substantially free of hydrogen and carbon monoxide; and
optionally, a further adsorbent layer for removing carbon dioxide from the product gas,
wherein the layer of catalyst comprises a mixture of manganese oxide and copper oxide and the length of the catalyst layer is sufficient to provide a residence time for the dry gas in the catalyst layer of at least 1.5 s.
18. The adsorption unit according to claim 17 , wherein the layer of catalyst comprises from 30 to 60 wt % manganese and from 10 to 30 wt % copper (based on total atomic mass).
19. The adsorption unit according to claim 17 , wherein the layer of catalyst is hopcalite.
20. The adsorption unit according to claim 17 , wherein the unit is a thermal swing adsorption unit.