Thesis (M.D.)--Columbia College, 1810. / Includes bibliographical references. Microform version available in the Readex Early American Imprints series.

Th.--Pharm.--Paris, 1869?

Thesis (Ph. D.)--University of Wisconsin, 1942. / Typescript. Includes bibliographical references (leaves [43-44]).

Les molybdates de bismuth présentent un grand intérêt en catalyse d’oxydation sélective du propylène. Leurs mécanismes de formation ont fait l’objet de nombreuses études mais leur compréhension reste encore incomplète.Dans un premier temps, la formation de γ-Bi2MoO6 au cours de sa synthèse par voie hydrothermale a été suivie in situ par diffraction X combinée à la spectrométrie d’absorption des rayons X (XAS) et à la diffusion Raman. Les mesures ont été réalisées au synchrotron à l’ESRF. Des informations sur la cinétique de réaction ont pu être déduites des données in-situ, mais ont dû être complétées par des analyses physico-chimiques ex-situ. L’étude montre que le catalyseur est généré selon un mécanisme en deux étapes, passant par la formation d’un molybdate de bismuth de structure proche de la fluorine à partir de laquelle se développent les cristaux lamellaires de γ-Bi2MoO6.Ce catalyseur a ensuite été utilisé en mode découplage redox dans l’oxydation du propène. Un Réacteur Catalytique à Membrane Dense (RCMD) dont le principe repose sur une membrane céramique dense, conductrice par ions oxydes O2-, qui sépare de façon étanche deux compartiments alimentés respectivement par l’hydrocarbure et l’air. La membrane de composition Bi25.75Mo10O68.625 adensifiée et mise en forme. L’étude montre que les activités catalytiques de la membrane (Bi25.75Mo10O68.625) seule ou avec le catalyseur (γ-Bi2MoO6) déposé à sa surface peuvent être modulées par l’application d’un courant électrique. L’apport en oxygène est suffisant pour permettre un travail en continu du catalyseur γ-Bi2MoO6 qui devrait être ré-oxydé par l’air co-alimenté avec le propène dans un réacteur classique. / Bismuth molybdates have drawn significant research interest because of their catalytic properties for propylene oxidation. Despite several studies dealing with the mechanism of their formation, uncertainties remain.The genesis of γ-Bi2MoO6 under hydrothermal conditions was first elucidated by an in-situ study combining High-Resolution Powder Diffraction (HRPD) / X-ray Absorption Spectroscopy (XAS) / Raman Scattering. Experiments were carried out at the European Synchrotron Radiation Facility. The informations on the two-step kinetics of reaction which were obtained by these experiments were completed by additional ex-situ characterizations. It was shown that the catalyst is formed via a bismuth molybdate of fluorite structure acting as a template for the layered γ-Bi2MoO6 crystals to be nucleated.In the second part, the catalytic properties of γ-Bi2MoO6 were studied in a the Catalytic Dense Membrane Reactor CDMR in which the reduction and reoxidation of catalyst were physically separated (redox decoupling). Bi25.75Mo10O68.625, known as a good oxide ion conductor, was used as the dense membrane, separating two compartments, one containing air and the other containing propylene to be oxidized selectively. The study has demonstrated that the catalytic activity of the γ-Bi2MoO6 and of the Bi25.75Mo10O68.625 dense membrane itself was modified by applying an electrical bias. In contrast to conventional reactors in which γ-Bi2MoO6 must be reoxidized by air cofed with propylene in a CDMR the oxygen supply is high enough for γ-Bi2MoO6 to operate continuously.

The use of bismuth in medicinal applications has been limited despite the many promising indications of its effectiveness in treatments for a large number of ailments. This is predominantly due to the lack of understanding of bismuth chemistry, including thermodynamic and kinetic aspects, thus hindering the design of improved drugs. This, in turn, is due to the difficulty in studying the complex chemistry of this element. Bismuth undergoes hydrolysis from below pH 1 and forms precipitates around pH 2 already, thus has to be studied from low pH. The most commonly used technique to determine stability constants, namely glass electrode potentiometry, cannot be employed in very acidic solutions. Complex formation has previously been studied by polarography where potential shifts and changes in current are used to determine solution species and evaluate stability constants. The benefits of employing polarography here are that low bismuth concentrations can be used to postpone precipitation and it can be used across the pH range. However, the diffusion junction potential becomes significant below pH 2 and changes with pH. Protocols to determine the stability of bismuth complexes using polarography were developed in this study. Firstly, the junction potential cannot be measured directly, so a witness metal ion was introduced into the solution to monitor its magnitude with changing pH. For this thallium (I) was used as it does not readily undergo complexation and hence potential shifts observed with changing pH is due to changes in the junction potential. This process was successfully tested on the cadmium(II)-picolinic acid system. Secondly, it was suggested that the reduction of bismuth(III) is quasi-reversible, so mechanisms of determining the reversible reduction potentials were investigated using the copper(II)-picolinic acid system, as copper(II) has a reduction potential almost identical to bismuth(III) and its reduction is also quasi-reversible. However, it was found that bismuth was reversibly reduced under the polarographic conditions employed. Thirdly, the free bismuth(III) potential had to be determined in order to calculate potential shifts due to complex formation. This potential cannot be measured directly either, so procedures were developed to determine this value by accounting for both hydrolysis and complex formation with the background electrolyte anion (nitrate). Three bismuth-ligand systems were studied where the ligands were picolinic acid, dipicolinic acid and quinolinic acid. It was necessary to determine the stability constants for these systems by using a combination of direct polarographic data interpretation and the use of virtual potentiometry.

Reproduction de : Thèse de doctorat : Génie physique : Metz : 1985. / Titre provenant de l'écran-titre. Notes bibliogr.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Michigan, 1911. / Cover title. "Reprinted from the Physical review, vol. XXXV, no. 2, August 1912."

Thesis (Ph. D.)--University of Michigan, 1911. / Cover title. "Reprinted from the Physical review, vol. XXXV, no. 2, August 1912."

Proefschrift--Leyden. / The large Hall-effect in bismuth was discovered by A. Righi. Includes bibliographical references.