The CO Working Capacity of Ni-MOF-74 and Corresponding Operating Conditions for CO/N₂ Adsorption Separation

Abstract

Ni-MOF-74 is among the most promising candidates for CO adsorption due to its highest CO adsorption capacity. However, the feasibility of using Ni-MOF-74 in actual CO/N 2 pressure swing adsorption (PSA) processing cannot be reliably inferred based solely on its adsorption capacity at normal temperature and pressure. Hence, we systematically studied its CO working capacity and regenerability at different test temperatures and pressure ranges by single-component static and binarycomponent dynamic (CO/N 2 , 50%/50% and 30%/70%, v/v) experiments. The static experiments preliminarily indicated an appropriate operating temperature of 100 °C with adsorption− desorption pressures in the range of 3.0−0.1 bar for the PSA process. The working capacity and regenerability of CO were evaluated as 3.41 mmol•g −1 and 66.21% (adsorption−desorption pressure: 3.0−0.1 bar, 100 °C). A higher temperature reduces the binding force between CO and Ni-MOF-74, so that more CO is desorbed, which leads to an increase in the working capacity and regenerability of CO. Furthermore, through CO/N 2 binarycomponent dynamic breakthrough experiments, the optimal operating temperature and CO adsorption partial pressure for the PSA process were determined as 100 °C and 1.5 bar at a total desorption pressure of 0.2 bar. Typically, for a CO/N 2 composition of 50%/50%, the CO working capacity and regenerability were 2.66 mmol•g −1 and 85.25% at 100 °C and a CO partial pressure of 1.5 bar (total CO adsorption pressure of 3.0 bar) at a total desorption pressure of 0.2 bar. These results may guide PSA process design and optimization for adsorbents with strong CO binding ability.