One-Pot Synthesis of Two-Linker Mixed Al-Based Metal–Organic Frameworks for Modulated Water Vapor Adsorption

Metal–organic frameworks (MOFs) as adsorbents have attracted interest in water-based adsorption applications due to their typical S-shape vapor adsorption isotherms and low regeneration temperature compared to traditionally used materials such as zeolites and silica gel. In this research, the mixed Al-based MOFs (CAU-10-H and Al-fumarate) with isophthalic acid and fumaric acid two ligands were fabricated by one-pot solvothermal method, which displayed a controllable water uptake step. The linker content included in mixed MOFs was assessed by 1H NMR spectroscopy, and the amount of each MOF crystal was uncovered by X-ray diffraction. Nitrogen physisorption data revealed that the BET surface area and pore size distribution of the mixed materials could be modulated between the limits of pure CAU-10-H and Al-fumarate. The dynamic adsorption displayed that their water adsorption isotherms could be tuned in the range of P/P0 = 14–30%. With the increase of the isophthalic acid molar fraction, the water vapor adsorption isotherms of the obtained adsorbents shifted to lower P/P0 values. The desorption performance of the mixed MOFs was between two pure MOFs. Using a one-pot synthetic approach, significant alterations in MOF water adsorption/desorption properties may be realized to accommodate the desired adsorption applications.