The use of in situ powder X-ray diffraction in the investigation of dolomite as a potential reversible high-temperature CO2 sorbent

Abstract

We report the use of gas sorption experiments and in situ powder X-ray diffraction to study the use of dolomite (MgCa(CO₃)₂) as a potential reversible high-temperature CO₂ sorbent. When dolomite is treated in inert atmosphere at 900 °C it decomposes into separate CaO and MgO rich phases and dolomite is never reformed upon CO₂ sorption. Gas sorption studies show that the calcined dolomite can go through several cycles of CO₂ sorption/desorption in a reversible manner, however, the sorption capacity diminishes with each cycle. Only calcium seems to be involved in the CO₂ sorption, while MgO acts as a carrier for the calcium phase. Some evidence of magnesium contamination of the calcium phase was found. BET and SEM measurements were carried out to find differences in the surface area/particle morphology that may explain similarities in the sorption capacities of dolomite and calcite (CaCO₃).