Process for producing and purifying a synthesis gas

A process for producing and purifying a synthesis gas stream, comprising:

• producing a CO- and H2-containing synthesis gas stream from a hydrocarbon-containing feed in a gas production unit,
• separating at least CO2 from the synthesis gas stream, and
• separating CO from the synthesis gas stream by cryogenic separation,
• wherein, prior to said separating of at least CO2, CO2 is present in said synthesis gas stream in a concentration in the range from 5% by volume to 30% by volume, and in said separating of at least CO2, CO2 is depleted to less than 10 ppm by volume in the synthesis gas stream by means of a first temperature swing adsorption upstream of said cryogenic separation,
• wherein, in said first temperature swing adsorption, CO2 is adsorbed on an adsorbent and the adsorbent is cooled by means of indirect heat transfer from the adsorbent to a heat transfer medium during adsorption of CO2, and the adsorbent loaded with CO2 is heated at least partly by indirect heat transfer from a heat transfer medium to the adsorbent to effect desorption of CO2;
• and
• in said first temperature swing adsorption CO2 is desorbed at a pressure in the range from 5 bar to 90 bar, and recirculated to the gas production unit as starting material for synthesis gas production.