Salicylaldehyde-assisted ZrO2-induced conversion approach to prepare high performance hollow fiber-supported UiO-66-NH2 membrane for hydrogen separation

The efficient separation of hydrogen from mixtures is essential to enable its widespread use as an alternative energy source to fossil fuel. UiO-66-NH2 membrane presents attractive application prospects in hydrogen purification. However, the cost-effective synthesis of UiO-66-NH2 membrane with high reproducibility, scalability, and stability remains a challenge. Herein, we developed a ZrO2-induced approach to prepare UiO-66-NH2 membrane supported on α-Al2O3 hollow fiber (HF). Commercial ZrO2 powders were first uniformly introduced onto the HF via a simple rotating method, followed by directly inducing the growth of well-intergrown UiO-66-NH2 membrane layer through these ZrO2 powders. The samples were well characterized by various physicochemical analysis techniques like SEM, EDX, XRD, N2 adsorption/desorption, CO2 adsorption, XPS, ATR-FTIR, etc. The pore aperture of UiO-66-NH2 membrane treated with salicylaldehyde (P-UiO-66-NH2) was reduced to 0.37 nm, which was slightly smaller than the kinetic diameter of CH4 (0.38 nm). Consequently, P-UiO-66-NH2 membrane demonstrated a promising H2/CH4 ideal selectivity of 21.7, which was superior to other related reports. The gas permeances of P-UiO-66-NH2 membrane were almost constant with the trans-membrane pressure difference, demonstrating that the membrane was compact and absent of pinholes. The membrane exhibited good thermal stability during the entire 80-h run between 30 °C and 200 °C with an average separation factor of 19.2–23.3 for binary H2–CH4 mixture. The membrane additionally presented good hydrothermal stability, mechanical strength and reproducibility. We believed that the developed preparation strategy has high potential in the development of UiO-66-NH2 membrane with high performance.