November 2012

Turning Down the Heat on Carbon

Unusual reaction eschews high temperatures and water to lock away climate-changing carbon dioxide.

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Image courtesy of PNNL

Detailed electron microscopy images show that carbon dioxide can react to form cubes of solid magnesium carbonate (the mineral magnesite) on a mineral surface.

The Science

A reaction has been discovered that requires relatively low temperatures and recycles water as it turns carbon dioxide into a solid mineral, trapping the greenhouse gas away from the atmosphere.

The Impact

Provides new insights on a reaction that transforms carbon dioxide into a solid mineral, an important reaction as scientists look to sequester carbon underground.

Summary

Keeping power plants' emissions of carbon dioxide sequestered underground, even in the event of an earthquake or other geological upset, will be facilitated by transforming the carbon dioxide into a mineral, such as anhydrous magnesite. This reaction occurs more readily at high temperatures and requires additional water – conditions that may not be viable in an underground reservoir. Scientists at Pacific Northwest National Laboratory discovered a reaction that forms the desired mineral at the relatively low temperature of 95°F and while recycling the water it needs. The team began with highly reactive nanometer-sized particles of an abundant mineral called forsterite, MgSiO4. They introduced water-saturated supercritical carbon dioxide to the particles. They examined the forsterite surface using scanning electron microscopy and characterized the molecules formed using four specialized spectrometers. The results show that within 3 to 4 days, the forsterite, water, and carbon dioxide form a mixture of two magnesium-based minerals: nesquehonite, which contains water, and the desired anhydrous magnesite, which does not. Water is continually used and released in the process, with the water driving the reaction. Over 14 days of reacting, the carbon dioxide was transformed into magnesite and a highly porous silica phase.

Contact

Andrew Felmy
ar.felmy@pnnl.gov

Kevin Rosso
kevin.rosso@pnnl.gov

Funding

DOE Office of Science Basic Energy Sciences (BES); research performed at the Environmental Molecular Sciences Laboratory, an Office of Science user facility managed by the Office of Biological and Environmental Research (BER).

Publications

Felmy AR et al. "Reaction of Water-Saturated Supercritical CO2 with Forsterite: Evidence for Magnesite Formation at Low TemperaturesExternal link."Geochimica et Cosmochimica Acta 91 271-282 (2012). [DOI: 10.1016/j.gca.2012.05.026.]

Related Links

http://www.pnl.gov/science/highlights/highlight.asp?id=1187External link

Highlight Categories

Program: BES, CSGB

Performer/Facility: DOE Laboratory, SC User Facilities, BER User Facilities, EMSL

Last modified: 5/2/2013 4:32:14 PM