Mo exchanged zeolite - preparation, characterization and catalytic properties

Show simple item record Huang, Minming en 2007-09-03T09:04:00Z en 2007-09-03T09:04:00Z en 1987 en
dc.identifier THESIS 87-154 en
dc.identifier.citation Thesis (PhD--Chemistry)--University of Auckland, 1987 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Molybdenum is ion exchanged into Y, mordenite and ZSM-5 zeolites using MoO2C12 as the starting material. It is proved that the determining factors of ion exchange are the stability and the diffusibility of MoO22+. The location of molybdenum in the zeolites is deduced in this work. EPR results suggested that all these zeolites can offer a similar coordination environment around the molybdenyl ion (MoO)n+. There are two types of coordination structure: distorted octahedral and tetrahedral symmetry. The latter has no counterpart on conventional oxide supported molybdenum catalysts. Moreover, an unusual O-2 species is detected in Mo-mordenite and Mo-ZSM-5. This O-2 is associated with the distorted tetrahedral coordinated molybdenum and has not been reported previously. The solvent function of zeolites is confirmed in this work by the migration of molybdenyl in the zeolite structure. The formation of an ammonia complex has a different effect on the migration from other molecules, such as water and pyridine. The molybdenyl ion moves into the tetrahedral coordination position under the influence of ammonia. The Mo-zeolites possess intact crystallinity and weaker acidity. A slight dealumination is observed, typically when a low pH value is used in the preparation. Mo-Y is an active catalyst for the selective oxidation of propene into acetone and aldehydes. Mo exchanged mordenites have remarkably increased life time in the disproportionation of toluene. Mo-ZSM-5 enhances the yield of light aliphatics in the methanol conversion reaction. The possible reasons for these catalytic properties are suggested to be based on the physicochemical properties of the catalysts. en
dc.language.iso en en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA9910305214002091 en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. en
dc.rights.uri en
dc.title Mo exchanged zeolite - preparation, characterization and catalytic properties en
dc.type Thesis en Chemistry en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The author en

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