Aluminophosphate monoliths with high CO 2 -over-N 2 selectivity and CO 2 capture capacity. and N 2 adsorption data indicated that the AlPO 4 -53 monoliths had an extraordinarily high CO 2 -over-N 2 selectivity from a binary gas mixture of 15 mol% CO 2 and 85 mol% N 2 . The estimated CO 2 capture capacity of AlPO 4 -17 and AlPO 4 -53 monoliths in a typical pressure swing adsorption (PSA) process at 20 C was higher than that of the commonly used zeolite 13X granules. Under cyclic sorption conditions, AlPO 4 -17 and AlPO 4 -53 monoliths were regenerated by lowering the pressure of CO 2 . Regeneration was done without application of heat, which would regenerate them to their full capacity for CO 2 adsorption. RSC

Zeolite NaA nanocrystals with a narrow particle size distribution were prepared by template-free hydrothermal synthesis in thermo-reversible methylcellulose gels. The effects of the amount of methylcellulose, crystallization time and hydrothermal treatment temperature on the crystallinity and particle size distribution of the zeolite NaA nanocrystals were investigated. We found that the thermogelation of methylcellulose in the alkaline Na2O-SiO2-Al2O3-H2O system played an important role in controlling the particle size. The synthesized zeolite nanocrystals are highly crystalline, as demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) shows that the nanocrystals can also display a well-defined facetted morphology. Gas adsorption studies on the synthesized nanocrystalline zeolite NaA showed that nanocrystals with a size of 100 nm displayed a high CO2 uptake capacity (4.9 mmol/g at 293 K at 100 kPa) and a relatively rapid uptake rate compared to commercially available, micron-sized particles. Low-cost nanosized zeolite adsorbents with a high and rapid uptake are important for large scale gas separation processes, e.g., carbon capture from flue gas.

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