Al‐based Isoreticular Metal‐Organic Frameworks with MIL‐53 Topology as Effective Adsorbents in Methane Purification

Abstract In the present investigation, an isoreticular series of Al‐based metal‐organic frameworks (MOFs) with MIL‐53 topology namely, MIL‐53(Al)‐FA, MIL‐53(Al)‐BDC, MIL‐53(Al)‐NDC and MIL‐53(Al)‐BPDC formed by organic linkers with different molecular size and correlated porosity were examined for their adsorption capacity for C 3 H 8 , C 3 H 6 , C 2 H 4, and CH 4 , and C 3 H 8 /CH 4 , C 3 H 6 /CH 4 , C 2 H 4 /CH 4 separation selectivity. C 3 H 8 and C 3 H 6 adsorption is found to be sensitive to van der Waals forces and increases with increasing micropore volume of the MOFs. Ideal Adsorption Solution Theory (IAST) has been applied to estimate binary C 3 H 8 /CH 4 , C 3 H 6 /CH 4 (C 3 /C 1 ), and C 2 H 4 /CH 4 (C 2 /C 1 ) selectivity. The MOFs investigated have shown high C 3 /C 1 selectivity with MIL‐53(Al)‐FA exhibiting exceptional C 3 H 8 /CH 4 and C 3 H 6 /CH 4 selectivity of 330 and 246, respectively, for the 5 : 95 (v/v) mixtures. MIL‐53(Al)‐FA also exhibited the highest C 2 /C 1 selectivity among them. The high affinity of MIL‐53 Al‐based MOFs for C 3 and C 2 hydrocarbons over C 1 make them suitable as adsorbents for methane purification.