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.