Adsorptive separation of acetylene from light hydrocarbons by mesoporous iron trimesate MIL-​100(Fe)

A reducible metal-​org. framework (MOF)​, iron(III) trimesate, denoted as MIL-​100(Fe)​, was investigated for the sepn. and purifn. of methane​/ethane​/ethylene​/acetylene and an acetylene​/CO2 mixts. by using sorption isotherms, breakthrough expts., ideal adsorbed soln. theory (IAST) calcns., and IR spectroscopic anal. The MIL-​100(Fe) showed high adsorption selectivity not only for acetylene and ethylene over methane and ethane, but also for acetylene over CO2. The sepn. and purifn. of acetylene over ethylene was also possible for MIL-​100(Fe) activated at 423 K. According to the data obtained from operando IR spectroscopy, the unsatd. FeIII sites and surface OH groups are mainly responsible for the successful sepn. of the acetylene​/ethylene mixt., whereas the unsatd. FeII sites have a detrimental effect on both sepn. and purifn. The potential of MIL-​100(Fe) for the sepn. of a mixt. of C2H2/CO2 was also examd. by using the IAST calcns. and transient breakthrough simulations. Comparing the IAST selectivity calcns. of C2H2/CO2 for four MOFs selected from the literature, the selectivity with MIL-​100(Fe) was higher than those of CuBTC, ZJU-​60a, and PCP-​33, but lower than that of HOF-​3.