(395y) Contracted Titanium Silicate (CTS-1): Aspects of Structure and CO2 Sorption

Engelhard Titanium Silicates (ETS) is a family of microporous titanium silicate materials first reported in 1989. Since then some variants were studied or implemented in applications. The Molecular Gate^TM technology can be used to upgrade CH₄ from mixtures of CH₄, N₂, and CO₂. It operates with a contracted titanium silicate (CTS-1) sorbent that relates to ETS-4. Surprisingly little is known for the structure and properties of such CTS-1 sorbents. We examined the potential of alkaline earth exchanged CTS-1 as sorbents for CO₂. All tested materials showed excellent levels of CO₂ uptake at 273 K. In particular, Mg²⁺ exchanged CTS-1 had high preferential CO₂ uptake (2.16 mmol/g, 273 K) with an ideal CO₂-over-N₂ selectivity of 14. CO₂ physisorbed rapidly with rates relevant for swing adsorption processes (80% of maximum capacity was reached in 45 seconds). We followed CO₂ sorption on Mg-CTS-1 by in situ infrared spectroscopy and characterized the physis- and chemisorbed CO₂ species. Vacuum and heat induced transformation of ETS-4 into CTS-1. In situ X-ray powder diffraction and electron diffraction were used to establish unit cell parameters of Mg-CTS-1. In summary, we showed that Mg-CTS-1 could potentially be a highly selective sorbent for carbon capture.