Steam assisted vacuum desorption process for carbon dioxide capture

A method for separating gaseous carbon dioxide from a gas mixture containing said gaseous carbon dioxide as well as further gases different from gaseous carbon dioxide by cyclic adsorption/desorption using a sorbent material adsorbing said gaseous carbon dioxide, using

• a unit containing an adsorber structure with said sorbent material, the unit being evacuable to a vacuum pressure of 400 mbarabs or less, and the adsorber structure being heatable to a temperature of at least 80° C. for the desorption of at least said gaseous carbon dioxide and the unit being openable to flow-through of the gas mixture and for contacting it with the sorbent material for the adsorption step,
• wherein the method comprises the following sequential and in this sequence repeating steps:
• (a) contacting said gas mixture with the sorbent material to allow at least said gaseous carbon dioxide to adsorb on the sorbent material under ambient atmospheric pressure conditions and ambient atmospheric temperature conditions in an adsorption step;
• (b) evacuating said unit to a pressure in the range of 20-400 mbarabs and heating said sorbent material in said unit to a temperature in the range of 80-130° C. in a desorption step and extracting at least the desorbed gaseous carbon dioxide from the unit and separating gaseous carbon dioxide from water by condensation in or downstream of the unit;
• (c) actively cooling the sorbent material under a pressure of the one in step (b) to a temperature larger or equal to ambient atmospheric temperature and re-pressurisation of the unit to ambient atmospheric pressure conditions;
• wherein in step (b) steam is injected into the unit to flow-through and contact the sorbent material under saturated steam or superheated steam conditions with a superheated steam temperature of up to 130° C. at the pressure level in said unit, and
• wherein the molar ratio of steam that is injected during the entire step (b) to the gaseous carbon dioxide released during the entire step (b) is less than 40:1.