As a cleaner, cheaper, and more globally evenly distributed fuel, natural gas has considerable environmental, economic, and political advantages over petroleum as a source of energy for the transportation sector. But its low energy density at ambient temperature and pressure has posed a severe challenge for onboard fuel storage in cars in the past.
An international team of researchers, using gas adsorption studies, in situ powder x-ray diffraction, and single-crystal x-ray diffraction, has managed to develop a variety of flexible metal–organic framework (MOF) materials for enhanced adsorption and desorption of natural gas (CH4). These MOFs, sponge-like 3D crystals with an extraordinarily large internal surface area, feature flexible gas-adsorbing pores, which expand under pressure. By forcing its way into this MOF crystal structure and opening and expanding the pores, the methane gas adsorption and desorption is “stepped.” This means the amount of methane that can be delivered to the engine is higher than for traditional, nonflexible adsorbents, which in turn has the potential to help make the driving range of an adsorbed-natural-gas (ANG) car comparable to that of a typical gasoline-powered car.
Work performed at the Advanced Photon Source, the Swiss Light Source, and the Advanced Light Source (Beamline 11.3.1).
J.A. Mason, J. Oktawiec, M.K. Taylor, M.R. Hudson, J. Rodriguez, J.E. Bachman, M.I. Gonzalez, A. Cervellino, A. Guagliardi, C.M. Brown, P.L. Llewellyn, N. Masciocchi, and J.R. Long, “Methane storage in flexible metal–organic frameworks with intrinsic thermal management,” Nature 527, 357 (2015).