title: In situ infrared spectroscopic study of forsterite carbonation in wet supercritical CO2.
abstract: Carbonation reactions are central to the prospect of CO(2) trapping by mineralization in geologic reservoirs. In contrast to the relevant aqueous-mediated reactions, little is known about the propensity for carbonation in the key partner fluid: supercritical carbon dioxide containing dissolved water ("wet" scCO(2)). We employed in situ mid-infrared spectroscopy to follow the reaction of a model silicate mineral (forsterite, Mg(2)SiO(4)) for 24 h with wet scCO(2) at 50 °C and 180 atm. The results show a dramatic dependence of reactivity on water concentration and the presence of liquid water on the forsterite particles. Exposure to neat scCO(2) showed no detectable carbonation reaction. At 47% and 81% water saturation, an Ångstrom-thick liquid-like water film was detected on the forsterite particles and less than 1% of the forsterite transformed. Most of the reaction occurred within the first 3 h of exposure to the fluid. In experiments at 95% saturation and with an excess of water (36% above water saturation), a nanometer-thick water film was detected, and the carbonation reaction proceeded continuously with approximately 2% and 10% conversion, respectively. Our collective results suggest constitutive links between water concentration, water film formation, reaction rate and extent, and reaction products in wet scCO(2).
authors.affiliation: Pacific Northwest National Laboratory, Richland, Washington 99352, USA. john.loring@pnl.gov
authors.forename: John S
authors.initials: JS
authors.lastname: Loring
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Thompson
authors.forename: Zheming
authors.initials: Z
authors.lastname: Wang
authors.forename: Alan G
authors.initials: AG
authors.lastname: Joly
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Sklarew
authors.forename: H Todd
authors.initials: HT
authors.lastname: Schaef
authors.forename: Eugene S
authors.initials: ES
authors.lastname: Ilton
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Rosso
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Felmy
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D057965:Carbon Sequestration; D007700:Kinetics; D011312:Pressure; D017655:Silicon Compounds / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D017655:Silicon Compounds; C503823:forsterite; D014867:Water; D002245:Carbon Dioxide