Adsorption and diffusion of H2, N2, CO, CH4 and CO2 in UTSA-16 metal-organic framework extrudates

Recently, a new metal-organic framework, named UTSA-16, has been proposed for removing carbon dioxide from gas mixtures by pressure swing adsorption in view of its high adsorption capacity and selectivity to this gas. Fundamental adsorption and diffusion parameters are required for designing a pressure swing adsorption (PSA) process with this adsorbent, which are lacking in the literature. In this work, adsorption Henry׳s law constants and reciprocal diffusion time constants of hydrogen, nitrogen, carbon monoxide, methane and carbon dioxide on UTSA-16 extrudates have been measured. The pure gas adsorption isotherms of these gases at high pressures and different temperatures have also been measured. Based on the pure gas adsorption equilibrium and kinetic parameters, a PSA cycle for hydrogen purification from steam-methane reforming off-gas (containing hydrogen, carbon monoxide, methane and carbon dioxide) has been simulated. Introducing a rinse step, the process can yield hydrogen with 99.99–99.999% purity with 93–96% recovery and productivities between 2 and 2.8 mol kg−1 h−1.