Atmospheric steam desorption for direct air 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, comprising:

• providing a sorbent material capable of adsorbing said gaseous carbon dioxide,
• providing a container containing an adsorber structure with said sorbent material,
• the adsorber structure being heatable to a temperature of at least 60° C. for the desorption of at least said gaseous carbon dioxide and
• the container being openable to flow-through of the gas mixture and for contacting the gas mixture with the sorbent material for adsorption,
• 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 and ambient atmospheric temperature in an adsorption step, using a speed of an adsorption gas flow;
• (b0) isolating said sorbent material with adsorbed carbon dioxide in said container from flow-through of gas mixture while maintaining the temperature in the sorbent;
• (b1) injecting a stream of steam essentially at ambient atmospheric pressure and thereby inducing an increase of the temperature of the sorbent material from ambient atmospheric temperature to a temperature between 60 and 110° C. while pushing out air contained in the container,
• (b2/b3) extracting at least the desorbed gaseous carbon dioxide from the container and separating gaseous carbon dioxide from water, including by condensation, in or downstream of the container, while still injecting and/or circulating steam at ambient atmospheric pressure into said container, thereby flushing and purging both steam and CO2 from the container;
• (c) bringing the sorbent material to ambient atmospheric temperature,
• wherein step (c) is carried out exclusively by contacting said gas mixture with the sorbent material under ambient atmospheric pressure conditions and ambient atmospheric temperature conditions to evaporate and carry away water in the container and to bring the sorbent material to ambient atmospheric temperature,
• or wherein the specific steam flow rate of a desorption process in steps (b1)-(b3) is constant,
• or wherein both the specific steam flow rate of a desorption process in steps (b1)-(b3) is constant and step (c) is carried out exclusively by contacting said gas mixture with the sorbent material under ambient atmospheric pressure conditions and ambient atmospheric temperature conditions to evaporate and carry away water in the container and to bring the sorbent material to ambient atmospheric temperature.

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

• providing a sorbent material capable of adsorbing said gaseous carbon dioxide,
• providing a container containing an adsorber structure with said sorbent material,
• the adsorber structure being heatable to a temperature of at least 60° C. for the desorption of at least said gaseous carbon dioxide and the container being openable to flow-through of the gas mixture and for contacting the gas mixture with the sorbent material for adsorption,
• 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 and ambient atmospheric temperature in an adsorption step, using a speed of an adsorption gas flow;
• (b0) isolating said sorbent material with adsorbed carbon dioxide in said container from flow-through of gas mixture while maintaining the temperature in the sorbent;
• (b1) injecting a stream of steam essentially at ambient atmospheric pressure and thereby inducing an increase of the temperature of the sorbent material from ambient atmospheric temperature to a temperature between 60 and 110° C. while pushing out air contained in the container,
• (b2/b3) extracting at least the desorbed gaseous carbon dioxide from the container and separating gaseous carbon dioxide from water, including by condensation, in or downstream of the container, while still injecting and/or circulating steam at ambient atmospheric pressure into said container, thereby flushing and purging both steam and CO2 from the container;
• (c) bringing the sorbent material to ambient atmospheric temperature,
• wherein the duration of steps (b1)-(b3), or of steps (b0)-(b3), is less than 6 minutes.