Top-down 2D view of the same metal-organic-framework pore lattice: open metal sites sit on a fixed grid, CO2 molecules random-walk through the gas phase between them, and a molecule that wanders within binding range of a free site sticks with a probability set by pore affinity — a Langmuir-type adsorption process, not a one-way reaction.
CO2(gas) + Site <-> CO2·Site
θ = capture / (capture + K·desorption)
- CO2 concentration — CO2 molecule density in the flue-gas or air stream being scrubbed.
- MOF binding sites — open metal sites in the 2D pore lattice available to host CO2.
- Pore affinity — how strongly the framework's chemistry attracts a passing CO2 molecule.
- Desorption/regen rate — how fast a filled site releases CO2 back into the gas phase during the heat/vacuum swing regeneration cycle — unlike a one-way reaction, capture here is reversible.
Direct-air-capture plants like Climeworks' cycle real sorbents through exactly this bind-then-regenerate loop to pull CO2 straight from ambient air.