CO2 Adsorption Isotherms and Isosteric Heat of a K-Rich Merlinoite-Type Zeolite (MER700) at 0 and 25 ˚C

As a versatile CO2 adsorbent, an 8MR low-silica merlinoite exhibits cation-gating behavior, dictating flexible framework response to CO2 uptake. This Short Communication reports the synthesis of K-rich MER-type (MER700) with a low silica-to-alumina ratio (Si/Al ~ 2.2). We validated the physical properties through structural characterization by XRD, FTIR, and SEM-EDS. Volumetric gas adsorption reveals a CO2 capture capacity of 2.33 mmol/g at 25 ˚C and 1 bar, which jumps to 3.71 mmol/g at 0 ˚C. These results verify the cation-gating that flexes the lattice-site MER700 structure during CO2 uptake, the isotherm profile, and the strongest sites during the low loading.