Removing mesopores from metal-organic framework MIL-100(Cr) membranes for superior CO2 separation

Abstract

Membranes with high CO2 permeance and satisfactory CO2/N2 selectivity have been in demand for industrial applications, especially for the first stage of two-stage membrane-based process. MOF membranes with abundant pores have the potential to achieve high CO2 permeance, but most current MOF membranes fall short of the requirements (CO2 permeance > 3000 GPU). Research on novel MOF membranes is urgently needed. Here, a new kind of non-crystalline (NC) MIL-100(Cr) membrane removed mesopores is fabricated by a non-fine assembly process. NC-MIL-100(Cr) possesses similar bonding structure and surface properties to crystalline MIL-100(Cr), but delivers more suitable pore size and high processibility for membrane formation. NC-MIL-100(Cr) membranes are prepared under different Cr3+ concentrations in reaction solution and secondary growth durations, among which NC-MIL-100(Cr) membranes prepared with Cr3+ concentration of 2 mmol/mol DMF and secondary growth duration of 36 h display CO2 permeance of about 4638 GPU and CO2/N2 selectivity of about 35 for mixed CO2/N2 (15/85, v/v) separation, as well as CO2 permeance of about 8670 GPU for single CO2 permeation.