Materials Science

Mining for Pores

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Science  07 Oct 2011:
Vol. 334, Issue 6052, pp. 19
DOI: 10.1126/science.334.6052.19-b

Porous networks within coal can determine its value as a fuel; porosity helps define how well certain types of coal burn and whether methane in the pores can be extracted efficiently from coal beds as an additional source of energy. Determining the porosity of complex natural materials such as coal is difficult, because a sample may contain many networks of pores that can be often disconnected from each other and from the surface of samples. Although several techniques for measuring porosity exist, Melnichenko et al. used small-angle neutron scattering to examine the interconnectivity of pores within coal samples as a function of pore size in a noninvasive and quantitative manner. They compared the scattering profiles of a coal sample in a vacuum and the same sample saturated with contrast-matching gases that fill accessible pores and make them invisible to the neutron beam. The analysis confirms that the proportion of isolated and accessible pores varies widely based on coal type, but also shows that pore accessibility varies with gas overpressure. These results may eventually help determine the feasibility of enhanced methane recovery from coal beds by injecting CO2 gas at high pressure.

Fuel 90, 10.1016/j.fuel.2011.06.026 (2011).

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