Description
Biogas produced by the digestion of organic matter comprises mainly CH4 and CO2. The separation via their selective adsorption can produce two valuable gas products and the utilization can prevent greenhouse gas emissions. We evaluate the layered montmorillonite-rich bentonite clay as a sorbent. The spacing between its negatively charged layers is set by (the size of) exchangeable (in)organic cations and sorbed water, and is thereby tunable. First, we discuss the effect of the cation size (without sorbed water) on the CO2 and CH4 sorption (in the interlayer space) of the material and identify a range that permits CO2 sorption, but can exclude the larger CH4 molecule. (The CO2/CH4 sorption selectivity is up to ~35 for Cs-exchanged bentonite.) Second, as the interlayer spacing of montmorillonite with a (sub-)monolayer of water is within this range, we discuss the synergistic and competitive effects of the co-sorption of water on the CO2 and CH4 sorption of the cheaper (than Cs-) Mg-, Ca-, and Na-exchanged bentonites. Finally, we demonstrate the ability of particles of the different materials to separate both gases in a lab-scale sorption column. Besides the large selectivity, the fast diffusion within the particles and the typical regeneration time without external heating of only several minutes are of particular interest. Functionalized clays thus seem a promising alternative for conventional sorbents that often suffer from a trade-off between kinetics and selectivity.| Period | 24 Jan 2024 |
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| Event title | NWO Physics@Veldhoven 2024 |
| Event type | Conference |
| Location | Veldhoven, NetherlandsShow on map |