Preparation, Characterization and Experimental Investigation of the Separation Performance of a Novel CaO‐based CO₂ Sorbent for Direct Air Capture

Abstract

The capture of CO2 from air via direct air capture (DAC) is a promising way to reduce the carbon dioxide concentration in the atmosphere. The carbonation of calcium‐based adsorbents using ambient conditions is particularly interesting for DAC due to its high theoretical CO2 uptake capacity and its low cost. In this paper, a new preparation method of synthetic calcium oxide‐based pellets for a DAC process was investigated. Their CO2 capture performance was studied experimentally in a fixed‐bed column and characterization was performed via Brunauer‐Emmett‐Teller (BET) analysis, mercury porosimetry, X‐ray diffraction, and scanning electron microscopy. Higher heating rates during the precursor calcination process and higher relative humidities during the carbonation process were found to lead to higher CO2 capture efficiencies. All prepared pellets showed good mechanical stability.

Direct Air Carbon Capture and Recovery Utilizing Alkaline Solution Circulation

“…Moreover, the characteristics of amine adsorbents will be degraded by repeated adsorption and desorption . In order to improve the adsorption capacity and lower the cost, David Keith et al developed a technology for capturing carbon dioxide based on alkaline solutions [e.g., KOH, NaOH, Ca­(OH) 2 ]. , This method offers substantial benefits in terms of raw material costs and a high CO 2 removal effectiveness (>74%). , However, the calcination of CaCO 3 at elevated temperatures demands high energy consumption (5.25–8.1 GJ/t CO 2 ), and the contact tower packing has a low specific surface area (200 m 2 /m 3 ). , Furthermore, DAC with the alkaline solution faces a substantial challenge in maintaining stable operation with efficient CO 2 absorption and less-frequent replenishment . As a modular distributed capture device, DAC has the ability to integrate with renewable energy sources like solar and wind power .…”

“…21 In order to improve the adsorption capacity and lower the cost, David Keith et al . 22,23 This method offers substantial benefits in terms of raw material costs and a high CO 2 removal effectiveness (>74%). 10,24 However, the calcination of CaCO 3 at elevated temperatures demands high energy consumption (5.25−8.1 GJ/t CO 2 ), 25 and the contact tower packing has a low specific surface area (200 m 2 /m 3 ).…”