Patent ID: 8632697

Claim:
A method for producing a gas comprising at least 80 vol % carbon monoxide, calculated on the total volume of the gas, from a gas mixture comprising 5-50 vol % methane, 10-50 vol % carbon dioxide, 20-65 vol % carbon monoxide, 10-40 vol % hydrogen and 10-55 vol % nitrogen, calculated on the total volume of the gas mixture, said method comprising, in sequence, the following steps: (1) feeding a gas mixture through a column comprising an adsorbent bed, said gas mixture comprising 5-50 vol % methane, 10-50 vol % carbon dioxide, 20-65 vol % carbon monoxide, 10-40 vol % hydrogen and 10-55 vol % nitrogen, calculated on the total volume of the gas mixture, with upon commencement of said feeding, the bed and column being pre-saturated and pre-pressurized to a pressure in the range of 20 to 80 bar absolute (bar a) with pure hydrogen, or with a mixture of hydrogen and nitrogen, and discharging effluent from the other end of said bed, and continuing said feeding and said discharging until a carbon monoxide comprising gas has reached at least 45% of the length of the bed and has reached at most 80% of the length of the bed, calculated from the end of the bed at which the gas mixture is being fed; and (2) ceasing the feeding of the gas mixture comprising methane, carbon dioxide, carbon monoxide and hydrogen, and reducing the pressure in the column and the bed to about 5 to 10 bar a; and (3) rinsing the column and the adsorbent bed by feeding a gas comprising at least 95 vol % methane, or a gas comprising at least 95 vol % carbon dioxide, through the column and adsorbent bed, the column and bed being at a pressure in the range of 15 to 75 bar a, and discharging effluent from the other end of said bed, and continuing said feeding and said discharging until at least 60% of the carbon monoxide that was present in the bed at the commencement of this rinsing step is discharged from the other end of said bed; and (4) rinsing the column and the adsorbent bed by feeding a gas comprising at least 95 vol % carbon dioxide through the column and adsorbent bed, the column and bed being at a pressure in the range of 15 to 75 bar a, and discharging effluent from the other end of said bed, and continuing said feeding and said discharging until at least 60% of the methane that was present in the bed at the commencement of this rinsing step is discharged from the other end of said bed; and (5) ceasing the feeding of a gas comprising at least 95 vol % carbon dioxide, and reducing the pressure of the column and adsorbent bed to a pressure in the range of 1 to 5 bar a; and (6) rinsing the column and adsorbent bed by feeding a mixture of hydrogen and nitrogen through the column and adsorbent bed the column and bed being at a pressure in the range of 1 to 5 bar a, and (7) pressurizing the column and adsorbent bed to a pressure in the range of 15 to 75 bar a by feeding a mixture of hydrogen and nitrogen.