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Speciation and location of Co2+, Mn2+ and Ni2+ in the extraframework positions of the dehydrated zeolite matrix of ferrierite structure were studied in detail using FTIR spectroscopy of antisymmetric T–O–T vibrations of the zeolite framework. Me2+–ferrierites were prepared by the ion exchange of the NH4– and Na–zeolite forms and by impregnation of the NH4 form. Bare Me2+ occupies all three known cationic sites in dehydrated cationic zeolite. The wavenumbers of bands of individual cations in individual sites were identified. At low Me2+ loadings (Me2+/Al < 0.15), Me2+ replaces two protonic sites and exclusively bare Me2+ is present in dehydrated samples. Sets of such samples were employed for the estimation of extinction coefficients of Co2+, Mn2+ and Ni2+ in cationic sites. These coefficients differ for individual cations but are the same for a cation at different sites. Ion exchange to the NH4 form allows preparation of samples with maximum possible loading of bare Me2+ only for Co2+. In the case of Mn2+, exchange to the Na-parent zeolite or impregnation is required for this purpose while samples with maximum loading by bare Ni2+ can be prepared only by impregnation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ratio of Al pairs and single Al atoms in zeolites can be tuned in a wide range. [•] Corresponding local negative charges balance bare divalent cations or metal-oxo species. [•] These cation/metal-oxo species control the activity in N2O and NOx related reactions. [ABSTRACT FROM AUTHOR]

Shape‐selective reactions: Highly selective catalysts are obtained by alkaline and subsequent acid leaching of conventionally prepared zeolites. Active sites that are located in the shape‐selective environment of micropores and accessible through mesopores (see picture) provide high selectivity and activity in acid‐catalyzed reactions. [ABSTRACT FROM AUTHOR]

Highly active oxygen capable to selectively oxidize methane to methanol at low temperature can be prepared in transition-metal cation exchanged zeolites. Here we show that the α-oxygen stabilized by the negative charges of two framework aluminum atoms can be prepared by the dissociation of nitrous oxide over distant binuclear cation structures (M(II)...M(II), M = cobalt, nickel, and iron) accommodated in two adjacent 6-rings forming cationic sites in the ferrierite zeolite. This α-oxygen species is analogous to that known only for iron exchanged zeolites. In contrast to divalent iron cations, only binuclear divalent cobalt cationic structures and not isolated divalent cobalt cations are active. Created methoxy moieties are easily protonated to yield methanol, formaldehyde, and formic acid which are desorbed to the gas phase without the aid of water vapor while previous studies showed that highly stable methoxy groups were formed on isolated iron cations in iron exchanged ZSM-5 zeolites. Selective oxidation of methane in zeolites is economical but the details of the responsible active sites are still unclear. Here the introduction of divalent transition metal cations into the zeolite matrix generates alpha-oxygen atoms which are active species for catalytic methane oxidation. [ABSTRACT FROM AUTHOR]