(389d) Thermodynamic and Kinetic Studies of Mineral Trapping of Carbon In Geologic Formations

The ever rising emission of anthropogenic CO2 has been one of the critical challenges faced by the global community. One of the most stable and long-term solutions for storing CO2 is via carbon mineralization where minerals containing metal oxides of Ca or Mg are reacted with CO2 to produce thermodynamically stable Ca- and Mg-carbonates that are insoluble in water. Carbon mineralization can be carried out ex-situ or in-situ. The kinetic of in-situ mineral trapping via carbonation is naturally very slow. However, ex-situ carbon mineralization involves mining and mineral processing, which can be quite energy-intensive. Thus, this work focuses on the chemical enhancement of in-situ mineral carbonation and the effect of mineral trapping on the stability of injected CO2 in geologic formations. Various silicate minerals such as olivine (Mg2SiO4), labradorite ((Ca,Na)(Al,Si)4O8) and basalt (mixture of silicate minerals) are selected for thermodynamic and kinetic studies. The kinetics of mineral dissolution and subsequent carbonation steps are first independently studied, and both Visual MINTEQ and Geochemist's Workbench are used for thermodynamic calculations. Particularly, the effects of ionic strength and chemical additives on the mineral dissolution, which has been known as a rate limiting step, are investigated using both a differential bed reactor and a batch reactor. The reaction parameters including temperature, pressure, reactive surface area, and pH are also studied. These results will provide important kinetic data to be used in the reaction path model for predicting the fate of injected CO2 in geologic formations.