Systems and methods for moisture enhanced carbon dioxide desorption for direct air capture

A method for direct air capture of carbon dioxide, comprising:

• providing a substrate, including:
• one or more sorbents, wherein the one or more sorbents includes an alkali-containing compound dispersed on a metal oxide carrier;
• and
• a concentration of catalyst,
• contacting ambient air with the substrate, the ambient air including a concentration of carbon dioxide;
• adsorbing an amount of the concentration of carbon dioxide to the one or more sorbents on a surface of the substrate;
• preparing a desorption medium including an inert gas and an amount of moisture to desorb the carbon dioxide;
• contacting the substrate with the desorption medium;
• heating the substrate to between about 150° C. and about 200° C.;
• desorbing carbon dioxide from the surface into the desorption medium;
• and
• isolating a carbon dioxide product stream from the desorption medium,
• wherein a moisture content of the desorption medium is greater than about 1 mol %.

A system for direct air capture of carbon dioxide, comprising:

• at least one substrate, including:
• one or more sorbents dispersed on a metal oxide carrier;
• and
• a concentration of catalyst,
• wherein the one or more sorbents include:
• an alkali-containing compound including K2O, Na2O, or
• combinations thereof,
• an alkaline earth metal-containing compound including CaO, MgO, BaO, or combinations thereof,
• or combinations thereof,
• the metal oxide carrier includes porous Al2O3, and the catalyst includes elemental nickel, ruthenium, or combinations thereof,
• an ambient air feedstream in fluid communication with the at least one substrate;
• an inert gas feedstream in fluid communication with the at least one substrate;
• a humidifier in fluid communication with the inert gas feedstream and the at least one substrate, the humidifier configured to maintain an environment proximate the at least one substrate with a moisture content greater than about 1 mol %;
• a heat source in communication with the substrate, and
• a product stream including a concentration of carbon dioxide desorbed from the substrate.