Self-Assembled Core–Shell Structure MgO@TiO<sub>2</sub> as a K<sub>2</sub>CO<sub>3</sub> Support with Superior Performance for Direct Air Capture CO<sub>2</sub>
Ke Wu, Shuai Peng, Guojie Ye, Zuofeng Chen, Deli Wu
Abstract
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.