(269g) Carbon Dioxide Uptake On Sorbents with Narrow Pore Window Aperatures: Zeolite (NaKA), (Silico)Aluminum Phosphates (AlPO4:s and SAPOs) and Titanium Silicate (CTS-1)

Adsorption driven CO₂ capture needs adsorbents with a range of desirable properties; these properties include high CO₂ adsorption capacity, high CO₂ selectivity over other gases including N₂ and CH₄, satisfactory mechanical and thermal properties. Here, we summarize results on our recent studies on microporous materials with narrow window apertures. Such narrow apertures can enhance the CO₂-over-N₂ selectivity as N₂ has a larger kinetic dimension than CO2 in microporous solids. We showed that zeolite NaKA with an optimal 17% K⁺ exchange was highly selective for CO₂ sorption (ideal selectivity 172, capacity 3.4 mmol/g, 298 K 101 kPa) and we synthesized nano-sized zeolite NaKA for improved adsorption kinetics. Our studies on aluminum phosphates (AlPO₄:s) and silico aluminum phosphates (SAPOs) showed that many of these materials had significant ideal CO₂-over-N₂ selectivity (AlPO-21, ideal selectivity = 32, 273 K 101 kPa) and high CO₂ adsorption capacities (SAPO-56, 5.4 mmol/g at 273 K, 101 kPa). The phosphates based materials were also less hydrophilic than traditional zeolite sorbents and had almost no lost in CO₂ capacities during cycle adsorption. Certain version of contracted titanium silicate (CTS-1) can be used for upgrading of natural gas and biogas. Our study on titanium silicates revealed that CTS-1, in particular its Mg²⁺ form (Mg-CTS-1), offered high CO₂ capacity (2.1 mmol/g, 273 K 101 kPa) and high ideal selectivity over N₂ (ideal selectivity ~ 14). We studied these adsorbents with a wide range of techniques, including volumetric adsorption, in situ infrared spectroscopy and in situ powder X-ray diffraction. These studies demonstrated the strengths of these adsorbents, and explored the potential of using different materials in adsorption driven carbon capture and storage (CCS).