Experiments and DFT study on modified CaO-based adsorbents for enhanced CO 2 capture

Abstract

CaO-based adsorbents for carbon capture represent a promising technology for reducing carbon emission. In this study, we prepare metal oxide-doped multifarious CaO-based adsorbents using the hydration method. We investigate the effect of various working conditions, such as temperature and carbonation time, on different adsorbents in a fixed-bed reactor under multiple carbonation–calcination cycles. We examine the behavior of different metal oxides-doped synthetic adsorbents using density functional theory calculation based on experiments. The results prove that 5 wt% ZrO2-doped adsorbents show excellent CO2 adsorption efficiency, which reaches up to 38.4% after 20 carbonation–calcination cycles at 700 °C with 15 vol% CO2. The adsorbents doped with other metal oxides are also useful for CO2 capture to varying degrees. The adsorption energy of CO2 molecules on modifiequationed adsorbents is higher than that on pure CaO, especially for Zr, where the adsorption energy reached 2.37 eV. The calculation results are in good agreement with the experimental data.