Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst.

This work investigates the acid sites in a commercial ZSM-5 zeolite catalyst by a combination of spectroscopic and physical methods. The Brønsted acid sites in such catalysts are associated with the aluminum substituted into the zeolite lattice, which may not be identical to the total aluminum content of the zeolite. Inelastic neutron scattering spectroscopy (INS) directly quantifies the concentrations of Brønsted acid protons, silanol groups, and hydroxyl groups associated with extra-framework aluminum species.

Proton and Oxide Ion Conductivity in Palmierite Oxides.

Solid proton and oxide ion conductors have key applications in several hydrogen-based and energy-related technologies. Here, we report on the discovery of significant proton and oxide ion conductivity in palmierite oxides AVO (A = Sr, Ba), which crystallize with a framework of isolated tetrahedral VO units. We show that these systems present prevalent ionic conduction, with a large protonic component under humidified air ( ∼ 0.

High oxide ion and proton conductivity in a disordered hexagonal perovskite.

Oxide ion and proton conductors, which exhibit high conductivity at intermediate temperature, are necessary to improve the performance of ceramic fuel cells. The crystal structure plays a pivotal role in defining the ionic conduction properties, and the discovery of new materials is a challenging research focus. Here, we show that the undoped hexagonal perovskite BaNbMoO supports pure ionic conduction with high proton and oxide ion conductivity at 510 °C (the bulk conductivity is 4.

Hexagonal perovskite derivatives: a new direction in the design of oxide ion conducting materials.

Various structural families have been reported to support oxide ion conductivity; among these, perovskite conductors have received particular attention. The perovskite structure is generally composed of a framework of corner-sharing octahedral units. When the octahedral units share their faces, hexagonal perovskites are formed.

Relationship between the Crystal Structure and Electrical Properties of Oxide Ion Conducting BaWNbO.

The oxide ionic conductor BaWNbO has been synthesized as part of an investigation into the new class of BaM'M''O (M' = W, Mo; M'' = Nb) oxide-ion conducting hexagonal perovskite derivatives. The substitution of W for Nb in BaWNbO leads to an increase in the oxygen content, which enhances the low-temperature ionic conductivity. However, at 400 °C, the ionic conductivity of BaWNbO is still significantly lower than the molybdenum compound BaMoNbO.