MIL-91(Ti), a small pore metal-organic framework which fulfils several criteria: an upscaled green synthesis, excellent water stability, high CO2 selectivity and fast CO2 transport
Résumé
A multidisciplinary approach combining advanced experimental and
modelling tools was undertaken to characterize the promises of a
small-pore type Ti-based metal-organic framework, MIL-91(Ti) for CO2
capture. This material was prepared using two synthesis strategies, i.e.
under hydrothermal conditions and under reflux, and its single
component adsorption behaviour with respect to CO2, CH4 and N-2 was
first revealed by gravimetry measurements. This hydrophilic and highly
water stable MOF is characterized by a relatively high CO2 adsorption
enthalpy. Molecular simulations combined with in situ powder X-ray
diffraction evidenced that this is due to the combined interaction of
this probe with N-H and P-O groups in the phosphonate linker. High CO2
selectivities in the presence of either N-2 or CH4 were also predicted
and confirmed by co-adsorption measurements. The possibility to prepare
this sample under reflux represents an environmentally friendly route
which can easily be upscaled. This green synthesis route, excellent
water stability, high selectivities and relatively fast transport
kinetics of CO2 are significant points rendering this sample of utmost
interest for CO2 capture.