L. González Tejuca

This reference offers an overview of the bulk and surface properties of perovskite-like structures, and provides the latest discussions on the applications of these materials and processes. It also introduces ceramic methods for the processing of perovskite-derived high Tc cuprates.;Examining every available procedure for synthesizing high-surface-area perovskite oxides, this book: delineates processing techniques for preparing perovskite-derived high-critical-temperature superconductors; illustrates the relevance of physiochemical methods to investigate bulk and surface structures of perovskite compounds; explicates the importance of surface composition in the context of catalytic behaviour; summarizes methods of changing stoichiometry; shows how to design perovskite oxides for a given purpose; reviews key solid-state properties; and presents the major applications.

The adsorption of oxygen and isobutene and the catalytic activity for propene and isobutene oxidation have been studied on a series of LaMO3(M = Cr, Mn, Fe, Co and Ni) perovskite oxides. Coadsorption results point to the non-competitive adsorption of oxygen and isobutene; i.e. these molecules adsorb on different centres. Oxygen adsorption underwent a remarkable increase after isobutene had been preadsorbed on these oxides (enhanced adsorption). Activation energies for complete oxidation ranged between 16 kcal mol–1(LaMnO3, LaCoO3 and LaNiO3) and 31 kcal mol–1(LaFeO3). LaCrO3 showed some activity for methacrolein formation. Adsorption and catalytic-activity profiles showed maxima for LaMnO3 and LaCoO3. These results are discussed within the framework of the ideas of Dowden and Wells on the local symmetry of surface cations and its influence on chemisorption and catalysis and show the importance of localized interactions in the processes studied.