Paving the way for methane hydrate formation on metal–organic frameworks (MOFs)

The presence of a highly tunable porous structure and surface chemistry makes metal–organic framework (MOF) materials excellent candidates for artificial methane hydrate formation under mild temperature and pressure conditions (2 °C and 3–5 MPa). Experimental results using MOFs with a different pore structure and chemical nature (MIL-100 (Fe) and ZIF-8) clearly show that the water–framework interactions play a crucial role in defining the extent and nature of the gas hydrates formed. Whereas the hydrophobic MOF promotes methane hydrate formation with a high yield, the hydrophilic one does not. The formation of these methane hydrates on MOFs has been identified for the first time using inelastic neutron scattering (INS) and synchrotron X-ray powder diffraction (SXRPD). The results described in this work pave the way towards the design of new MOF structures able to promote artificial methane hydrate formation upon request (confined or non-confined) and under milder conditions than in nature.

We acknowledge the UK Science and Technology Facilities Council for the provision of beam time on the TOSCA spectrometer (Project RB1510448) and financial support from the European Commission under the 7th Framework Programme through the “Research Infrastructures” action of the “Capacities” Programme (NMI3-II Grant number 283883). J. S.-A. acknowledges financial support from MINECO Projects: MAT2013-45008-p and CONCERT Project-NASEMS (PCIN-2013-057) and from Generalitat Valenciana (PROMETEO2009/002). The authors acknowledge the Spanish synchrotron ALBA for beam time availability. E. V. R.-F. gratefully acknowledges a Ramon y Cajal grant (RyC-2012-11427). F. R. and J. L. J. acknowledge financial support from MINECO through projects MAT2012-38567-C02-01, Consolider Ingenio 2010-Multicat CSD-2009-00050 and Severo Ochoa SEV-2012-0267, and Generalitat Valenciana (Prometeo).