App117 Water and CO2 co-sorption landscape in CALF-20, a prototypical MOF for post combustion capture
This application note reports a detailed gravimetric study of carbon‑dioxide and water sorption on the metal‑organic framework CALF‑20, performed with the Surface Measurement Systems DVS Carbon Advanced instrument. The authors describe the importance of capturing CO₂ from humid gas streams and introduce CALF‑20 as a mildly hydrophobic, chemically and mechanically robust MOF that exhibits high CO₂ capacity (>3 mmol g⁻¹ at 25 °C) with a moderate isosteric enthalpy of 30–35 kJ mol⁻¹, and delayed water uptake due to partial hydrophobicity. The DVS Carbon platform provides independent, simultaneous control of CO₂ concentration (0 ppm–100 vol %) and relative humidity (0–98 % RH) over 5–450 °C, enabling systematic acquisition of single‑component isotherms, isosteric enthalpy calculations, and full three‑dimensional co‑sorption surfaces. Results show Type I CO₂ physisorption with minimal hysteresis, water sorption that only becomes significant above ~20 % RH, and temperature‑dependent uptake trends. Co‑sorption experiments, performed by scanning one component while holding the other at fixed background levels, reveal competitive and synergistic effects across the full CO₂–H₂O–temperature space, visualized as 3D sorption surfaces. The authors conclude that the comprehensive datasets generated are essential for process modeling, material screening, and optimization of carbon‑capture systems, and that the DVS Carbon’s capabilities are broadly applicable to other sorbents such as functionalized MOFs, amine‑grafted materials, zeolites, and porous carbons.
Topics
CALF‑20 as a Benchmark MOF for Humid CO₂ Capture
Presentation of CALF‑20’s structural features, mild hydrophobicity, high CO₂ capacity, moderate heat of sorption, and exceptional chemical/mechanical stability under humid and high‑temperature conditions.
DVS Carbon Advanced: Independent CO₂ and H₂O Control for Multidimensional Sorption Measurements
Overview of the gravimetric analyzer’s ability to vary CO₂ concentration (ppm–100 vol %) and relative humidity (0–98 % RH) across 5–450 °C, with sub‑microgram mass resolution, enabling systematic single‑ and co‑sorption experiments.
Comprehensive Co‑Sorption Mapping: 3D Sorption Surfaces and Competitive/Synergistic Interactions
Co‑sorption experiments with constant background of one component while scanning the other, integration of single‑component data to construct full 3D uptake surfaces across CO₂, H₂O, and temperature, highlighting regions of competition and potential synergy.
Implications for Process Design and Material Screening
Discussion of how the high‑resolution, multidimensional sorption datasets support process modeling, optimization of carbon‑capture cycles, and evaluation of other sorbents (functionalized MOFs, amine‑grafted sorbents, zeolites, porous carbons).