Factors affecting the direct mineralization of CO2 with olivine.

Olivine, one of the most abundant minerals existing in nature, is explored as a CO2 carbonation agent for direct carbonation of CO2 in flue gas. Olivine based CO2 capture is thermodynamically favorable and can form a stable carbonate for long-term storage. Experimental results have shown that water vapor plays an important role in improving CO2 carbonation rate and capacities. Other operation conditions including reaction temperature, initial CO2 concentration, residence time corresponding to the flow rate of CO2 gas stream, and water vapor concentration also considerably affect the performance of the technology.

Reaction kinetics of CO2 carbonation with Mg-rich minerals.

Due to their low price, wide availability, and stability of the resulting carbonates, Mg-rich minerals are promising materials for carbonating CO(2). Direct carbonation of CO(2) with Mg-rich minerals reported in this research for the first time could be considerably superior to conventional liquid extraction processes from an energy consumption perspective due to its avoidance of the use of a large amount of water with high specific heat capacity and latent heat of vaporization. Kinetic models of the reactions of the direct CO(2) carbonation with Mg-rich minerals and within simulated flue gas environments are important to the scale-up of reactor designs. Unfortunately, such models have not been made available thus far. This research was initiated to fill that gap. Magnesium silicate (Mg(2)SiO(4)), a representative compound in Mg-rich minerals, was used to study CO(2) carbonation reaction kinetics under given simulated flue gas conditions. It was found that the chosen sorbent deactivation model fits well the experimental data collected under given conditions. A reaction order of 1 with respect to CO(2) is obtained from experimental data. The Arrhenius form of CO(2) carbonation with Mg(2)SiO(4) is established based on changes in the rate constants of the chosen deactivation model as a function of temperature.