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

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