Efficient Separation of Acetylene-Containing Mixtures Using ZIF‑8 Membranes

Metal–organic
framework (MOF) membranes show great potential
in the separation of acetylene mixtures. In this work, we have prepared
ZIF-8 membranes on polyamide (PA) substrates for the highly selective
separation of acetylene/methane and acetylene/carbon dioxide mixtures.
The C2H2/CH4 and C2H2/CO2 mixtures can be successfully separated using
the ZIF-8 membranes, with separation factors of 12.1 and 1.8, respectively.
Based on the results of the cross-permeation tests of C2H2/CH4, CO2/CH4, and
C2H2/CO2, the separation mechanism
of C2H2/CH4 in our ZIF-8 membrane
can be attributed to a higher affinity for acetylene and molecular
sieving effect, while C2H2/CO2 separation
is related to thermodynamic factors. It is worth noting that this
is the first example of MOF membranes to successfully separate C2H2 from CH4 and CO2.