Adsorption of small molecules in LTA-type zeolites : 1. NH3, CO2, and H2O in zeolite 4A.
We have developed force fields for the calculation of adsorption of NH{sub 3}, CO{sub 2}, and H{sub 2}O on zeolite 4A by performing Gibbs ensemble Monte Carlo simulations to fit experimental isotherms at 298 K. The calculated NH{sub 3} and CO{sub 2} isotherms are in excellent agreement with experimental data over a wide range of temperatures and several orders of magnitude in pressure. We have calculated isotherms for H{sub 2}O in 4A using two different models and have found that H{sub 2}O saturates zeolite 4A even at pressures as low as 0.01 kPa for the range of temperatures studied. We have studied the geometry of the adsorption sites and their dependence on loading. At low pressures, CO{sub 2} molecules adsorb with their longitudinal axis pointing toward the center of the supercage, whereas at higher pressures, the two oxygen atoms are equidistant from the Na atom in the binding site.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1002061
- Report Number(s):
- SAND2003-2534J; ISSN 1520-5207; TRN: US201102%%578
- Journal Information:
- Proposed for publication in the Journal of Physical Chemistry B., Vol. 108, Issue 52; ISSN 1520-6106
- Country of Publication:
- United States
- Language:
- English
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