Ionic Clusters in Zeolites

Atomic resolution analysis of porous solids: A detailed study of silver ion-exchanged zeolite A

“…The cage is slightly tilted for a better observation of the 14 Ag (eight Ag + forming the cube and in the centre the Ag 6 octahedron). These conclusions are in agreement with the model proposed by Kim and Seff [23,26], who attributed the colour change to the presence of fully reduced, (over 400°C), Ag 0 6 clusters detected through single-crystal XRD studies. Subsequently, Jacobs et al [25] suggested that the colour change in completely (Ag-A) Fig.…”

“…There have been different studies on this system which led to different explanations for that colour change, resulting in two proposed models: one of them which explained that effect by the formation of octahedra in the sodalite cages, and the other by the formation of linear trimers in the same cages [24][25][26]. Fig.…”

1,3-Butadiene Adsorption over Transition Metal Polycation Exchanged Faujasites

“…As follows from Table data, due to TrM polycation formation, the sum of all cation equivalents incorporated into faujasites significantly exceeds 100% at the rate of monocations. Actually, it is a characteristic feature for polycation exchanged zeolites, , and the excess of the total ion exchange degree is related to polycations. In the case of double Cu, Mn containing sample, TrM polycation contents are given in Table in proportion to the corresponding monocation exchange degrees.…”

“…In this connection, zeolites, especially faujasites in transition metal (TrM) cation exchanged forms, arouse interest due to their ability to form polycations of diversified compositions. Numerous confirmations of TrM polycation stabilization in faujasite intracrystalline cages have been obtained over the past 10–15 years. − Such cluster metal or metal oxide polycations have the general formula [TrM α O β ] n + , where α varies from 2 to 8, β varies from 0 to 4, and n varies from 2 to 6. Accordingly, cluster polycations have sizes in the nano- or subnanometer range of 4–16 Å or 0.4–1.6 nm that should define an enhanced chemisorption and catalytic activity of the materials.…”

Aberration-Corrected STEM Analysis of a Cubic Cd Array Encapsulated in Zeolite A

“…The general formula of an aluminum-containing zeolite is M x / n Al x Si 1–x O 2 , where each aluminum unit introduces a negative charge that must be compensated by cationic species M n + . Through a variety of chemical treatments, metal clusters can be located within the zeolite cages, giving potential uses in fields such as optics, electronics, photocatalysis, and sensors. − The activity of these metallic species is directly related to their size, geometry, composition, and chemical/physical environment; therefore, an in-depth characterization of the clusters and of the zeolite framework is indispensable for understanding the behavior of the materials and to underpin better and more rational design.…”