One Ca 2+ Site in CaNaY Zeolite Can Attach Three CO 2 Molecules.

To design efficient CO 2 capture materials, it is necessary to ensure a high adsorption capacity. We recently reported that one Na + site in NaY zeolite can attach two CO 2 molecules. However, the process is not suitable for practical use because it proceeds at a low temperature. Here, we present results on CO 2 adsorption on CaNaY zeolites, demonstrating that one Ca 2+ site can attach three CO 2 molecules. The ν 3 ( 13 CO 2 ) mode arising from the natural 13 C abundance allows for easy infrared monitoring of the processes: it appears at 2298, 2294, and 2291 cm -1 for the complexes with one, two, and three CO 2 ligands, respectively. The 12 CO 2 molecules in the polyligand complexes interact vibrationally, leading to the split of the ν 3 ( 12 CO 2 ) modes. At ambient temperature, Ca 2+ (CO 2 ) 2 complexes predominate at >1 mbar CO 2 and triligand species begin to form at 65 mbar. The obtained results show that CaY zeolites can be very effective CO 2 capture materials.