Purification
of propylene from the propyne (C3H4)/propylene
(C3H6) mixture is a significant
and challenging process in the chemical industry. Nowadays, the removal
of propyne from propylene mainly relies on the energy-intensive hydrogenation
catalyzed by noble metals. We herein report three gallate-based metal–organic
frameworks, namely, M(II)-gallate (M = Ni, Mg, Co), which provide
excellent performance in terms of removing propyne from the propyne/propylene
mixture (1:99, v/v). The C3H4 uptake capacities
of Mg-, Co-, and Ni-gallate can reach 3.75, 3.21, and 2.65 mmol/g,
while the C3H6 uptake capacities are only 1.50,
1.49, and 0.9 mmol/g respectively, at ambient conditions. Particularly,
the productivities of 99.9999% pure C3H6 in
Co-gallate and Mg-gallate were 1580 and 1420 mL/g, respectively, outperforming
the state-of-the-art material USTA-200 (1400 mL/g). The adsorption
mechanism was further investigated by using the first-principle dispersion-corrected
density functional theory calculations, revealing that the excellent
C3H4/C3H6 separation ability
of M-gallate originates from stronger supramolecular interactions
and C–H···O interactions between the hydrogen
atoms from C3H4 and oxygen atoms from M-gallate
frameworks. Besides, the M-gallate materials also show excellent regeneration
ability. Thus, this work demonstrates that the family of M-gallate
materials shows industrially promising porous materials for propylene
purification by the adsorption process.