Outlook of MgO-based CO2 capture

https://doi.org/10.1016/j.cogsc.2022.100645

“We conclude that MgO-based sorbents promoted with AMS are highly suited for CO₂ capture applications in precombustion schemes involving high p_CO2 (>5 bar) in the temperature range of 300–550 °C. Current material developments aim at improving the rate of CO₂ sorption by using suitable mixtures of AMS (including nitrates and carbonates). From a practical perspective, studies have also begun to investigate how the activity of MgO-based sorbents can be maintained over multiple cycles of CO₂ sorption and release through the introduction of sinter-resistant, structural stabilizers [78,79], how the gas environment (e.g. the presence of steam) influences the two reaction steps [3], and how efficient, mechanically stable MgO-based sorbents can be manufactured at larger scales [80, 81, 82]. It currently seems unlikely that MgO-based sorbents will find application in postcombustion schemes involving the formation of stable carbonates, purely based on thermodynamic considerations. For sorbent development, it is important to understand that the rapid transition between MgO and MgCO₃ (or Mg-double carbonates) does not imply that CO₂ is removed efficiently from a gas stream. Experiments using packed bed reactors analyzing breakthrough curves are needed to quantify the CO₂ capture efficiency to assess whether a sorbent formulation is indeed suitable for a particular CO₂ removal application. Last, as thermodynamic data for Mg-based carbonates is not reliable, more experimental studies are required to determine the equilibrium partial pressure of CO₂ as a function of temperature, especially for sorbents containing and forming multiple carbonate species with unknown reaction pathways.”