Self-Assembled Core-Shell Structure MgO@TiO 2 as a K 2 CO 3 Support with Superior Performance for Direct Air Capture CO 2 .

Traditional carbon capture and storage technologies for large point sources can at best slow the rate of increase in atmospheric CO 2 concentrations. In contrast, direct capture of CO 2 from ambient air, or "direct air capture" (DAC), offers the potential to become a truly carbon-negative technology. Composite solid adsorbents fabricated by impregnating a porous matrix with K 2 CO 3 are promising adsorbents for the adsorption capture of CO 2 from ambient air. Nevertheless, the adsorbent can be rapidly deactivated during continuous adsorption/desorption cycles. In this study, MgO-supported, TiO 2 -stabilized MgO@TiO 2 core-shell structures were prepared as supports using a novel self-assembled (SA) method and then impregnated with 50 wt % K 2 CO 3 (K 2 CO 3 /MgO@TiO 2 , denoted as SA-KM@T). The adsorbent exhibits a high CO 2 capture capacity of ∼126.6 mg CO 2 /g sorbent in direct air adsorption and maintained a performance of 20 adsorption/desorption cycles at 300 °C mid-temperature, which was much better than that of K 2 CO 3 /MgO. Analysis proved that the core-shell structure of the support effectively inhibited the reaction between the active component (K 2 CO 3 ) and the main support (MgO) by the addition of TiO 2 , resulting in higher reactivity, thermal stability, and antiagglomeration properties. This work provides an alternative strategy for DAC applications using adsorbents.