posted on 2019-09-23, 21:29authored byChunhui Wu, Lien-Yang Chou, Liuliu Long, Xiaomeng Si, Wei-Shang Lo, Chia-Kuang Tsung, Tao Li
Metal–organic
frameworks (MOFs) is a promising class of
sorbent materials for swing adsorption gas separation. However, although
sorption kinetics plays a major role in column breakthrough experiments,
it is rarely studied with MOF materials. This is largely because the
synthesis of uniform yet separation-relevant MOFs is a challenging
task. Here, we report a dual-modulation approach for the synthesis
of well-defined Mg-MOF-74 hexagonal rods with an extremely uniform
size distribution (polydispersity index = 1.02). Through epitaxial
growth and wet chemical etching, uniform hollow Ni-MOF-74 with plate-shaped
caps were obtained. CO2 adsorption kinetic study shows
that hollow Ni-MOF-74 exhibits 54% faster diffusion rate compared
to solid Ni-MOF-74 due to a shortened diffusion length, despite their
identical CO2 uptake capacity. This has led to a 21% extension
of column breakthrough time during CO2/N2 separation
under identical conditions.