Investigation of the Different Carbonate Phases and Their Formation Kinetics during Mg(OH)2 Slurry Carbonation

Abstract

Carbon mineralization is recognized as one of the safest and most permanent methods for storing anthropogenic CO2. Combining CO2 capture and storage eliminates energy-intensive sorbent regeneration and uncertainties associated with geological sequestration of CO2. Carbonation of Mg(OH)2 in a gas–solid system has been investigated, but both the reaction kinetics and the overall conversion were limited. Derived from silicate minerals or industrial wastes, a Mg(OH)2 slurry can react with dissolved CO2 to form a variety of magnesium carbonate phases with differing amounts of hydroxide and crystallized H2O incorporated within the carbonate crystal. In this study, slurry-phase Mg(OH)2 carbonation was investigated at moderate temperatures and CO2 pressures (up to 200 °C and 15 atm). Mg(OH)2 carbonation in the slurry phase involved heterogeneous dissolution of Mg(OH)2 and CO2, in addition to homogeneous precipitation of magnesium carbonates. The reaction conditions responsible for hydrated and anhydrous carbonate...