Zeolites have been increasingly used in various application areas such as industry, agriculture, environmental protection, and even medicine. Although, there are no certain figures on the total amount of these minerals the world, some countries e.g. Cuba, USA, Russia, Japan, Italy, South Africa, Hungary and Bulgaria, have important reserves and production potentials. According to reports of 200...

Ion exchange represents one of the most promising processes for ammonium recovery from municipal wastewater (MWW). However, previous studies on ion did not optimize process or evaluate its robustness under real operational conditions. This experimental study aimed at (i) developing a procedure selection sorbent selective removal/recovery MWW, (ii) validating by applying it to several sorbents, ...

The effect of anharmonic corrections to the vibrational energies of extended systems is explored. Particular attention is paid to the thermodynamics of adsorption of small molecules on catalytically relevant systems typically affected by anharmonicity. The implemented scheme obtains one-dimensional anharmonic model potentials by distorting the equilibrium structure along the normal modes using ...

P R O We describe the application of transition path sampling methods to the methanol coupling reaction in the zeolite chabazite; these methods have only been recently applied to complex chemical systems. Using these methods, we have found a new mechanism for the formation of the first C C bond. In our mechanism, the reaction, at 400 C, proceeds via a two-step process: (1) the breaking of the C...

The changes in the spectra of the acidic group in chabazite are studied by quantum chemical calculations. The zeolite is modeled by two clusters consisting of eight tetrahedral atoms arranged in a ring and seven tetrahedral atoms coordinated around the zeolite OH group. The potential energy and dipole surfaces were constructed from the zeolite OH stretch, in-plane and out-of-plane bending coord...

Zeolites have been increasingly used in various application areas such as industry, agriculture, environmental protection, and even medicine. Although, there are no certain figures on the total amount of these minerals the world, some countries e.g. Cuba, USA, Russia, Japan, Italy, South Africa, Hungary and Bulgaria, have important reserves and production potentials. According to reports of 200...

Introduction SAPO-34 is a silicoaluminophosphate zeolite with 8-membered ring windows (~0.38nm) displaying chabazite structure. SAPO-34 is an efficient catalyst showing improved catalytic performance in reactions such as methanol conversion to olefins [1], oxidative dehydrogenation of propane [2], conversion of light alkenes [3]. Its catalytic properties are mainly attributed to its mild acidit...

DFT periodic, ONIOM, and cluster studies with all-electron basis sets are applied to Cu(I) exchanged zeolites and silicoalumino-phosphate analogs with faujasite and chabazite topology. The reactivity of the cations at different cation positions is probed by NO adsorption. In the ONIOM approach, the cation center and the nearest framework environment are described by DFT, whereas a larger part o...