Cellulose acetate mixed-matrix membranes doped with high CO2 affinity zeolitic tetrazolate-imidazolate framework additives

Introducing CO2 affinity additives into membrane is one of significant approaches to improve the CO2 permeability of membranes for natural gas sweetening. In current work, high performance mixed-matrix membranes were successfully obtained using the cellulose acetate (CA) and the zeolitic tetrazolate-imidazolate frameworks (ZTIFs) with highly CO2 affinity as matrix and additive respectively. The interaction between CA matrix and ZTIFs was verified by the FT-IR. The SEM, EDS and XRD were used to evaluate the morphology properties of these membranes. The CO2 permeability of CA/ZTIFs mixed-matrix membranes which is closely correlated to the loading of high CO2 affinity ZTIF additive were in a range of 9.59–15.85 Barrer, implying the indispensable role of the ZTIF additive in changing the CO2 dissolution and diffusion behavior inside the membranes. The ideal compatibility and gas selectivity proved the great potential of the ZTIFs additives for the gas separation application. [Display omitted] •Specially designed ZTIF-1 was chosen as the CO2 solubility boosting additive to match the cellulose acetate matrix.•A strategy to address the compatibility issues of the membranes was proposed by constructing hydrogen bond interactions.•The CO2 permeability coefficient and the selectivity of CO2/CH4 were increased to 1.6 times and 1.8 times respectively.