Kinetic separation of CO2/CH4 mixtures with Ni-MOF-74@Al2O3 core–shell composites
Dirk Otter, Sebastian‐Johannes Ernst, Lorenz Krätz, H.‐J. Bart
Abstract
Abstract A novel core–shell species for the adsorption-based separation of carbon dioxide (CO 2 ) from methane (CH 4 ) is introduced by hydrothermal synthesis of Ni-MOF-74 on mesoporous spherical Al 2 O 3 carrier substrate. The material was characterized and the shell thickness determined by means of optical and scanning electron microscopy as well as volumetric adsorption and fluid displacement experiments. Kinetic experiments with Ni-MOF-74@Al 2 O 3 core–shell composites carried out at 303.15 K and at pressures up to 10 bar expose remarkably dominating uptake rates for CO 2 over CH 4 . In the contrary Ni-MOF-74@Al 2 O 3 appears to be unselective according to equilibrium data at the same conditions. Dynamic breakthrough experiments of binary CH 4 /CO 2 -mixtures (at 303.15 K and 5 bar) prove the prevailing effect of adsorption kinetics and the storage function of the mesoporous core. This statement is supported by a considerable boost in CO 2 -selectivity and capacity compared to adsorption equilibria measured on pure Ni-MOF-74 by the factor of 55.02 and up to 2.42, respectively.