The capture of low concentration CO2 presents numerous challenges. Here, we report that zinc containing chabazite (CHA) zeolites can realize high capacity, fast adsorption kinetics, and low desorption energy when capturing ca. 400 ppm CO2. Control of the state and location of the zinc ions in the CHA cage is critical to the performance. Zn 2+ loaded onto paired anionic sites in the sixmembered rings (6MRs) in the CHA cage are the primary sites to adsorb ca. 0.51 mmol CO2/g-zeolite with Si/Al= ca. 7, a 17-fold increase compared to the parent H-form. The capacity is increased further to ca. 0.67 mmol CO2/g-zeolite with Si/Al= ca. 2 due to more paired sites for zinc exchange. Zeolites with double six-membered rings (D6MRs) that orient 6MRs into the cages give enhanced uptakes for CO2 adsorption with zinc exchange. The results reveal that zinc exchanged CHA and several other small pore, cage containing zeolites are worthy of further investigation for the capture of low concentration CO2.

The capture of low concentration CO2 presents numerous challenges. Here, we report that zinc containing chabazite (CHA) zeolites can realize high capacity, fast adsorption kinetics, and low desorption energy when capturing ca. 400 ppm CO2. Control of the state and location of the zinc ions in the CHA cage is critical to the performance. Zn 2+ loaded onto paired anionic sites in the sixmembered rings (6MRs) in the CHA cage are the primary sites to adsorb ca. 0.51 mmol CO2/g-zeolite with Si/Al= ca. 7, a 17-fold increase compared to the parent H-form. The capacity is increased further to ca. 0.67 mmol CO2/g-zeolite with Si/Al= ca. 2 due to more paired sites for zinc exchange. Zeolites with double six-membered rings (D6MRs) that orient 6MRs into the cages give enhanced uptakes for CO2 adsorption with zinc exchange. The results reveal that zinc exchanged CHA and several other small pore, cage containing zeolites are worthy of further investigation for the capture of low concentration CO2.

Chemical shifts from the 11 B nuclear magnetic resonance (NMR) spectra of crystalline borosilicate minerals with highly ordered, tetrahedrally coordinated boron atoms (B) linearly correlate with the local geometric parameters related to the B−O−T angles (T denotes a tetrahedrally coordinated atom) obtained from single-crystal X-ray diffraction. The correlations between the 11 B NMR chemical shifts and structural parameters are similar in functional form to the well-known correlations of 29 Si and 27 Al NMR chemical shifts with structural features of silicates and aluminosilicates, respectively. These correlations enable the use of 11 B NMR chemical shifts to elucidate the local geometry of tetrahedrally coordinated B and aid in establishing B ordering among the crystallographic T-sites within crystalline borosilicates.