(608d) Miniaturizing Dynamic Column Breakthrough Measurements to Measure Gas and Vapour Adsorption Equilibrium on Milligram Quantities of Adsorbents

Dynamic column breakthrough (DCB) is a technique that can measure adsorption equilibrium, kinetics and column dynamics using a packed bed of a given adsorbent. Quantitative DCB is traditionally performed with a packed column of a pelletized adsorbent, in the gram to kilogram scale, to mitigate pressure-drop issues. Due this constraint, many newly synthesized, crystalline, and rare materials are unable to be tested in a DCB apparatus. In this presentation, a dynamic column breakthrough (DCB) apparatus is detailed that overcomes the previously mentioned shortcomings and can accurately measure single and multi-component equilibrium loadings and column dynamics of milligram-scale quantities of adsorbent rapidly. Due to the much smaller size of the DCB apparatus, breakthroughs can be performed in as little as a few seconds, and are quantifiable. The material balance is derived and presented for the DCB apparatus that accounts all possible sources of accumulation, within the solid, fluid and extra-column volumes. The apparatus was tested with dry gases on a previously studied zeolite 13X sample [1] and a commonly studied activated carbon. Single-component adsorption equilibrium data from vacuum to 1.2 bar and 30, 40 and 50°C was measured for N₂, CH₄ and CO₂ in a volumetry apparatus. This statically collected data was compared with data collected in the DCB. The equilibrium loadings for both adsorption and desorption agree with the statically collected data within 5%. Unary H₂O vapor experiments were also studied between 10 and 90% relative humidity on various adsorbents at 30°C, and agree with measurements from the literature. Afterwards, this technique was extended for multicomponent mixtures. First, mixtures of N₂ and CH₄ were tested. Since, both N₂ and CH₄ exhibit linear isotherm trends on zeolite 13X, they should not experience any competition between each other. This was verified with the DCB measurements. The collected N₂ and CH₄ equilibrium data all agree with the linear isotherm predictions. N₂/CH₄ mixtures were also studied on the activated carbon at 30, 40 and 50°C. The measured data suggests the mixture is weakly nonideal, which is agreement with the literature. Finally, mixtures of CO₂ and CH₄ were tested. CO₂ and CH₄ on zeolite 13X exhibit very nonideal adsorption competition. These findings suggest that the DCB can measure single and multicomponent gas and vapor adsorption equilibrium and column dynamics precisely and accurately.

References:

1. Wilkins, N. S. and Rajendran, A. Adsorption2 (2019): 115-133.