Eutectic doped Li4SiO4 adsorbents using the optimal dopants for highly efficient CO2 removal

Abstract

Eutectic doping has been considered one of the most efficient and economic approaches to modify Li₄SiO₄-based CO₂ adsorbents. Nevertheless, neither systematic screening nor selection criteria have been provided for the prediction of potential dopants. Hence, in this work, 12 kinds of molten salt dopants, including 5 unreported, were systematically compared and screened. First, the feasibility of candidates was evaluated, and unsuitable options were excluded after clarifying the detailed reasons such as volatilization loss and decomposition. Then, the capacity enhancing effects as well as the economies of residual dopants were calculated and the optimal option, NaF, which possesses the highest capacity enhancement of 0.45 g CO₂ per g dopant and one of the best economies of 375.0–642.9 g CO₂ per $, was eventually screened out. The modification effect of dopants was further investigated to reveal a strong relationship with their eutectic temperature, and this is the reason why L-NaF, which possesses the lowest eutectic temperature (475 °C), exhibited the greatest performance. Finally, based on the above findings, three criteria were summarized for the future selection of potential eutectic dopants, which are of great importance for the development and application of high-performance doped Li₄SiO₄ adsorbents.