The Role of H2O in the Carbonation of Forsterite in Supercritical CO2

Journal Article · Fri Jul 01 04:00:00 EDT 2011 · International Journal of Greenhouse Gas Control, 5(4):1081-1092

DOI:https://doi.org/10.1016/j.ijggc.2011.05.013· OSTI ID:1024075

Kwak, Ja Hun; Hu, Jian Z; Turcu, Romulus VF; Rosso, Kevin M; Ilton, Eugene S; Wang, Chong M; Sears, Jesse A; Engelhard, Mark H; Felmy, Andrew R; Hoyt, David W

The water concentration dependence of forsterite carbonation in supercritical CO2 (scCO2) at 80°C and 76 bars was investigated by a combination of NMR, XRD, TEM and XPS. Reaction products were not detected using scCO2 alone without added H2O. When trace amounts of water were included, limited reaction was observed. Below saturation, reaction products were a mixture of partially hydrated/hydroxylated magnesium carbonates and hydroxylated silica species that were mainly in an amorphous state, forming a non-resolved layer on the forsterite surface. At water concentrations above saturation, where forsterite was in contact with both a CO2-saturated aqueous fluid and a water-saturated scCO2 fluid, solid reaction products were magnesite (MgCO3) and an amorphous polymerized SiO2 dominated by Q4, and to a lesser extent by Q3 silica coordination. Formation of these phases implies H2O initially bound in precursor hydrated/hydroxylated reaction products was liberated, inducing further reaction. Hence, for a given fluid/mineral ratio there is a water threshold above which a significant portion of the water serves in a catalytic role where more extensive carbonation reaction occurs. Defining the role of water, even in low water content environments, is therefore critical to determining the long term impact of CO2 reactivity in the subsurface.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1024075
• Report Number(s): PNNL-SA-76665; 32911; 39937
• Journal Information: International Journal of Greenhouse Gas Control, 5(4):1081-1092, Journal Name: International Journal of Greenhouse Gas Control, 5(4):1081-1092 Journal Issue: 4 Vol. 5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AMORPHOUS STATE
CARBON DIOXIDE
Environmental Molecular Sciences Laboratory
MAGNESIUM CARBONATES
MIXTURES
PRECURSOR
SATURATION
SILICA
TRACE AMOUNTS
WATER
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY