Bubbling synthesis and high-temperature CO2 adsorption performance of CaO-based adsorbents from carbide slag

Abstract

Carbide slag used as low-cost adsorbents for high-temperature CO2 capture has widely researched; however, the sintering at high calcination temperature often resulted in an obvious decay of CO2 capture performance after multiple CO2 capture cycles. In this work, a new strategy of synthetic CaO-based adsorbents from carbide slag via the bubbling approach was reported to stabilize the pore structure of adsorbents, to improve the sintering resistance of adsorbents and to boost the CO2 adsorption capacity. Therefore, the influences of bubbling rate, stirring rate, reaction temperature, and carbide slag dosage on CO2 adsorption capacity of CaO-based adsorbents were systemically investigated at 750 °C for 1 h. The synthetic CaO-based adsorbent from carbide slag on the basis of following conditions: 200 sccm of CO2 bubbling, 1100 rpm/stirring, 40 °C of reaction temperature and 5 g of carbide slag dosage, presented the highest CO2 adsorption capacity of 619.8 mg/g and 542.6 mg/g in the 1st and 15th cycles, which were about 6.6% and 33.9% higher than that of original carbide slag (CS). This significant improvement in CO2 uptake capacity is due to more stable interconnected and 2–5 nm porous structure in the as-prepared CaO-based adsorbent, which outstandingly lowered down the sintering of adsorbents and stabilized the CO2 adsorption capacity during multiple CO2 capture cycles.