Parametrical Study on CO Capture from Ambient Air Using Hydrated KCO Supported on an Activated Carbon Honeycomb.

Potassium carbonate is a highly hygroscopic salt, and this aspect becomes important for CO capture from ambient air. Moreover, CO capture from ambient air requires adsorbents with a very low pressure drop. In the present work an activated carbon honeycomb monolith was coated with KCO, and it was treated with moist N to hydrate it. Its CO capture capacity was studied as a function of the temperature, the water content of the air, and the air flow rate, following a factorial design of experiments. It was found that the water vapor content in the air had the largest influence on the CO adsorption capacity. Moreover, the deliquescent character of KCO led to the formation of an aqueous solution in the pores of the carrier, which regulated the temperature of the CO adsorption. The transition between the anhydrous and the hydrated forms of potassium carbonate was studied by means of FT-IR spectroscopy. It can be concluded that hydrated potassium carbonate is a promising and cheap alternative for CO capture from ambient air for the production of CO-enriched air or for the synthesis of solar fuels, such as methanol.