Zeolite Phi is synthesized by two methods reported previously. Results from X-ray powder diffraction and scanning electron microscopy suggest that t h e materials are physical mixtures of chabazite and offretite; one sample has a small amount of phillipsite. The X-ray powder diffraction data from these samples, and those reported previously, are indexed and their unit-cell parameters compare we...

AECL’s CHEMIC process has effectively treated in excess of 4 million gallons of radiostrontiumcontaminated water since 1993. One aspect of the ongoing effort to expand the application of the process involves the use of powdered sorbents such as biomass in addition to natural zeolites in conjunction with precipitation for the removal of different contaminants including radiostrontium from waste ...

We report an unusual operating regime for a chabazite zeolite in which the adsorption selectivity for N2 over CH4 inverts from being more selective for N2 at 253 K, to becoming less selective with increasing temperature and eventually becoming selective for CH4 over N2 above 293 K.

The influence of the choice of the exchange-correlation functional (semilocal gradient corrected or hybrid functionals) on the electronic properties of metal-exchanged zeolites has been investigated for Cu- and Co-exchanged chabazite. The admixture of exact exchange in hybrid functionals increases the fundamental gap of purely siliceous chabazite, leading to better agreement with experiment and...

The generation of hexamethylbenzenium radical cations as the key reaction intermediate in chabazite-type molecular sieve acids (i.e., H-SAPO-34 and H-SSZ-13) during the methanol-to-olefin process has been directly evidenced by ESR spectroscopy.

There is limited research comparing nutrient removal in concentrated and dilute waste streams. Accordingly, the goal of this was to study effect dilution on ammonium potassium from real hydrolyzed urine using natural zeolites. The performance two zeolites, clinoptilolite chabazite, studied compared batch equilibrium experiments at four levels defined as volume divided by total solution (express...

Hybrid quantum mechanics:molecular mechanics (QM/MM) calculations of absolute deprotonation energies are performed with periodic boundary conditions for Brønsted sites of aluminosilicate bilayers with various Al/Si ratios (two-dimensional zeolite). The supercell method is applied and density functional theory is used. Much lower values are obtained (1042, 1069 and 1091 kJ mol(-1) for Al/Si = 1/...

We present an embedded cluster approach for modeling interactions in zeolites and an application of this model to the study of NH3 and NH4 adsorption in chabazite. This model utilizes the SCREEP (surface charge representation of the electrostatic embedding potential) formalism to include an accurate description of the Madelung potential in quantum mechanical calculations. The model is validated...