(552c) Modification of 13X Zeolite Via Atomic Layer Deposition for Post Combustion CO2 Capture

Post-combustion CO₂ capture is a technology in which CO₂ is captured directly from coal or natural gas flue gas. Several physical adsorbents, including zeolites, activated carbons, and MOFs, have been investigated for CO₂ capture performance. However, 13X zeolite is the only physical adsorbent utilized on a pilot scale for post-combustion CO₂ capture due to its high CO₂ working capacity, good CO₂/N₂ selectivity, excellent stability, and low cost. Atomic layer deposition (ALD) is a technique in which two or more self-limiting reagents are sequentially delivered as vapors to a material to fabricate coatings at the atomic level. In this work, 13X zeolite was modified via TiCl₄ and H₂O ALD to significantly improve the CO₂ capture properties. The ALD-modified 13X was characterized for CO₂ and N₂ adsorption behavior via isotherms, breakthrough curves, and cyclic gravimetric uptake at 30-70^oC. Relative to pristine 13X, ALD 13X demonstrated a 15-22% increase in CO₂ working capacity (5-15 kPa) and a 24-32% reduction in N₂ capacity (0-85 kPa). Analysis of CO₂ isotherms and calorimetry data suggests that the improved CO₂ capture properties were a result of passivated adsorption behavior. ALD 13X demonstrated an 11-17% reduction in CO₂ heat of adsorption and an 81-90% reduction in CO₂ Henry’s constant relative to pristine 13X. Furthermore, ALD 13X showed excellent stability with cyclic H₂O exposure and 350^oC regeneration. Overall, ALD 13X exhibits promising CO₂ capture performance under conditions relevant to post-combustion CO₂ capture when compared to 13X, which may result in cost and energy savings over adsorbent based technologies.