Reaction Mechanisms for Enhancing Mineral Sequestration of CO₂

Abstract

Storage of CO2 through mineral sequestration using olivine has been shown to produce environmentally benign carbonates. However, due to the formation of a rate-limiting reaction product layer, the rate of reaction is insufficient for large-scale applications. We report the results of altering the reactant solution composition and the resultant reaction mechanism to enhance the reaction rate. The products were analyzed for total carbon content with thermal decomposition analysis, product phase compositions with Debye-Scherrer X-ray powder diffraction (XRD), surface morphology with scanning electron microscopy (SEM), and composition with energy dispersive X-ray spectroscopy (EDXS). Carbon analysis showed that an increase in bicarbonate ion activity increased the olivine to carbonate conversion rate. The fastest conversion rate, 63% conversion in one hour, occurred in a solution of 5.5 M KHCO3. Additionally, SEM confirmed that when the bicarbonate ion activity was increased, magnesium carbonate product particles significantly increased in both number density and size and the rate passivating-reaction layer exfoliation was augmented.

Calcium Carbonate Precipitation for CO2 Storage and Utilization: A Review of the Carbonate Crystallization and Polymorphism

“…In the dissolution step, various additives including strong acids (i.e., HCl, HNO3, and H2SO4) Lin et al, 2008;Bobicki et al, 2012), organic acids (i.e., acetic acid, formic acid, succinic acid, oxalic acid, etc.) (Park et al, 2003;Park and Fan, 2004;Bałdyga et al, 2010;Zhao et al, 2013), salts, and alkali solution and ligands (Maroto-Valer et al, 2005;Jarvis et al, 2009;Lackner, 2009, 2011) have been investigated to date. Although the extraction efficiencies are promising, the use of such strong acids may provoke significant energy penalties associated with their recovery Olajire, 2013;Sanna et al, 2014).…”

A spatially resolved surface kinetic model for forsterite dissolution

“…As a result, the dissolution rate of olivine is linked to the evolution of the lithosphere and upper mantle (Sleep et al, 2004), the utility of olivine as an industrial feedstock for mineral carbonation (Oelkers and Cole, 2008), neutralization of acid mine drainage (Jambor et al, 2007), and geoengineering using enhanced silicate weathering (Koehler et al, 2010;Hartmann et al, 2013). Given the high reactivity of olivine, the surface chemistry and dissolution kinetics have been studied under a broad range of experimental conditions, including closedsystem (Giammar et al, 2005;King et al, 2010;Daval et al, 2011) and well-mixed flow-through dissolution experiments on powdered olivine samples (Pokrovsky and Schott, 2000b;Oelkers, 2001), as well as single crystals (Jarvis et al, 2009;Saldi et al, 2013). Characterization of the reaction products has also included a range of techniques, such as X-ray photoelectron spectroscopy (Pokrovsky and Schott, 2000a;Zakaznova-Herzog et al, 2008;Olsson et al, 2012), infrared spectroscopy (Pokrovsky and Schott, 2000a;Giammar et al, 2005;Loring et al, 2011), transmission electron microscopy (Bearat et al, 2006;Daval et al, 2011) and atomic force microscopy (King et al, 2014).…”

Olivine reactivity with CO2 and H2O on a microscale: Implications for carbon sequestration

“…It is also possible that the secondary mineral layer exfoliates when a critical thickness is reached (Jarvis et al, 2009). Béarat et al (2006) presented transmission electron microscopy (TEM) results showing an olivine surface with a 50 nm thick silica layer that formed at high temperatures and CO 2 partial pressures.…”