CO2/CH4 Separation by a Mixed Matrix Membrane of Polymethylpentyne/MIL-53 Particles

The effect of Materials Institute Lavoisier-53 (MIL-53) particles on gas transport properties of polymethylpentyne (PMP) was investigated. MIL-53 was added to the polymer matrix with different loadings of 10، 20 and 30 wt%. The properties of MIL-53 and prepared membranes were analyzed through FTIR، SEM and TGA methods. The adsorption of CO2 and CH4 was conducted and analyzed accurately through Langmuir equation to investigate the gas transport properties of membranes. The results from TGA showed that degradation temperature (Td) increases significantly with increasing MIL-53 loading. SEM images demonstrated that MIL-53 particles dispersed well in polymer matrix with no considerable agglomeration and no non-selective void formation at polymer/filler interface. In addition، CO2 and CH4 permeability measurement along with calculation of CO2/CH4 selectivity were performed. The results showed that the permeability of gases (especially for CO2) increased significantly by increasing the MIL-53 loading. Additionally، CO2/CH4 selectivity showed an increasing trend with increasing the MIL-53 weight percent. Unlike CH4، the CO2 solubility coefficient increased with increasing the MIL-53 loading because of high free volume of membrane and selective adsorption of CO2 with MIL-53. Despite CO2 solubility enhancement its diffusivity coefficient remained more or less unchanged. The enhancement in CH4 permeability has been mainly attributed to its slight incremental diffusivity due to the membrane''s increasingly higher free volume. Finally، a comparison between membranes performance and CO2/CH4 Robeson upper bound showed that، the performance of membranes improved due to the presence of MIL-53 which was very close to the Robeson bound.