The sorption of krypton in silicalite

Abstract

We present the results of a combined experimental and theoretical study of the sorption of Kr in the porous silica polymorph, silicalite. The experimental techniques are based on volumetric sorption studies and the theoretical methods on simulations using effective potentials. Both techniques reveal three main sites for sorption of the rare gas.

Computational modelling of intrinsic defects in the orthosilicates Y2SiO5 and Lu2SiO5

“…Such calculations showed that oxygen vacancy bounded with Si atoms are the most favourable point defects in YSO structure [18,19]. [35] 1305.248 0.3177 10.141 12.0 O shell − O shell [36] 22764.000 0.1490 46.084 12.0 Shell model Spring Lu core − Lu shell [37] 308.00 Lu core [37] Lu shell [37] Si core O core [33] O shell [33] 3.000 −0.277 Atomistic computer modelling techniques are efficient tool for defect studies because this approach allows to address many possibilities without long computational time cost and this thorough studies can be used as a guide for further investigations, both from the experimental and computational point of views. They are based on interatomic potentials and energy minimization of the lattice that represents a great gain in defect studies, although some optical and electronic properties are not accessible in this approach.…”

Stepped Propane Adsorption in Pure-Silica ITW Zeolite

“…This behavior has been attributed to the initial filling of channels followed by the filling of channel intersections, with indication of a transition of the adsorbate from a fluidlike to a solidlike phase. By contrast, the step found during Kr adsorption on pure-silica ZSM-5 was considered to be due to “the completion of the monolayer”, while the stepped isotherms of other small gases like Ar and CO have been related to a disorder–order, fluid-to-crystalline transition in the adsorbed phase. , This phase transition was suggested to be analogous to the spinodal decomposition involving a metastable liquidlike phase where the adsorbed molecules have a restrained mobility in the confined pore space and relax only under excess pressure to a more stable solidlike adsorbed phase …”