Structural Evolution of CO2-Filled Pure Silica LTA Zeolite under High-Pressure High-Temperature Conditions
- Univ. de Valencia (Spain)
- Atomic Weapons Establishment, Reading (United Kingdom); Imperial College London (United Kingdom)
- Diamond Light Source, Didcot (United Kingdom)
- Univ. Politècnica de València − Consejo Superior de Investigaciones Científicas, Valencia (Spain)
- Univ. of California, Los Angeles, CA (United States)
- ALBA-CELLS, Cerdanyola (Spain)
The crystal structure of CO2-filled pure-SiO2 LTA zeolite has been studied at high pressures and temperatures using synchrotron-based X-ray powder diffraction. Its structure consists of 13 CO2 guest molecules, 12 of them accommodated in the large α-cages and one in the β-cages, giving a SiO2/CO2 stoichiometric ratio smaller than 2. The structure remains stable under pressure up to 20 GPa with a slight pressure-dependent rhombohedral distortion, indicating that pressure-induced amorphization is prevented by the insertion of guest species in this open framework. The ambient-temperature lattice compressibility has been determined. In situ high-pressure resistive-heating experiments up to 750 K allow us to estimate the thermal expansivity at P ≈ 5 GPa. Our data confirm that the insertion of CO2 reverses the negative thermal expansion of the empty zeolite structure. No evidence of any chemical reaction was observed. Finally, the possibility of synthesizing a silicon carbonate at high temperatures and higher pressures is discussed in terms of the evolution of C–O and Si–O distances between molecular and framework atoms.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-06CH11357; EAR 11-57758; FG02-94ER14466
- OSTI ID:
- 1368292
- Journal Information:
- Chemistry of Materials, Vol. 29, Issue 10; ISSN 0897-4756
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
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