Interactions between catalysts and oxygen carriers in chemical looping processes
type: CreativeWork
description: This Dissertation considers the fundamentals and applications of materials composed of a metal catalyst supported on a reactive metal oxide, applied for chemical looping processes, using Ag/SrFeO3−δ as a model system. In chemical looping processes, lattice oxygen is provided from a metal oxide (termed the oxygen carrier) to generate purified oxygen, or, to react with a reducing gas (e.g. a hydrocarbon) to form oxygenated products, in the absence of gaseous oxygen. The oxygen carrier is then re-oxidised in air, in a separate step. Chemical looping has been investigated for a variety of selective oxidation reactions, either with the metal oxide oxygen carrier acting as both an oxygen reservoir and a catalyst for selective oxidation, or, by preparing particles composed of a metal catalyst supported on an oxygen carrier. During reduction, oxygen is transported from the lattice of the metal oxide to the surface of the metal catalyst. However, the interactions between the catalyst and the oxygen carrier, and the pathways taken by oxygen, are poorly understood, and hence form the subject of this Dissertation. To understand the influence of Ag on oxygen availability from SrFeO3−δ, kinetic studies were performed by measuring the rate of oxygen release and re-uptake from SrFeO3−δ with and without Ag (15 wt%) by reducing and oxidising the material in N2 and O2 (pO2 = 0.21 or 0.05 atm) in a packed bed. The presence of Ag increased the amount of oxygen released per redox cycle by more than three-fold at 500°C. From thermogravimetric experiments, interactions between Ag and SrFeO3−δ were shown to influence the thermodynamics of the material, with Ag increasing the concentration of oxygen vacancies at equilibrium, and hence lowering the oxygen stoichiometry under all investigated oxygen partial pressures (pO2 = 10−5−0.21 atm). Characterisation studies under simulated reaction conditions were performed to understand the changes in bulk and surface properties of Ag/SrFeO3−δ during c…
abstract: This Dissertation considers the fundamentals and applications of materials composed of a metal catalyst supported on a reactive metal oxide, applied for chemical looping processes, using Ag/SrFeO3−δ as a model system. In chemical looping processes, lattice oxygen is provided from a metal oxide (termed the oxygen carrier) to generate purified oxygen, or, to react with a reducing gas (e.g. a hydrocarbon) to form oxygenated products, in the absence of gaseous oxygen. The oxygen carrier is then re-oxidised in air, in a separate step. Chemical looping has been investigated for a variety of selective oxidation reactions, either with the metal oxide oxygen carrier acting as both an oxygen reservoir and a catalyst for selective oxidation, or, by preparing particles composed of a metal catalyst supported on an oxygen carrier. During reduction, oxygen is transported from the lattice of the metal oxide to the surface of the metal catalyst. However, the interactions between the catalyst and the oxygen carrier, and the pathways taken by oxygen, are poorly understood, and hence form the subject of this Dissertation. To understand the influence of Ag on oxygen availability from SrFeO3−δ, kinetic studies were performed by measuring the rate of oxygen release and re-uptake from SrFeO3−δ with and without Ag (15 wt%) by reducing and oxidising the material in N2 and O2 (pO2 = 0.21 or 0.05 atm) in a packed bed. The presence of Ag increased the amount of oxygen released per redox cycle by more than three-fold at 500°C. From thermogravimetric experiments, interactions between Ag and SrFeO3−δ were shown to influence the thermodynamics of the material, with Ag increasing the concentration of oxygen vacancies at equilibrium, and hence lowering the oxygen stoichiometry under all investigated oxygen partial pressures (pO2 = 10−5−0.21 atm). Characterisation studies under simulated reaction conditions were performed to understand the changes in bulk and surface properties of Ag/SrFeO3−δ during c…
author: Harrison, Alexander
language: eng
keywords: chemical looping, catalysis, oxygen carriers, in-situ spectroscopy, kinetics
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/559c5045-90ac-436b-932a-9bc4fb306310/download
license: http://purl.org/NET/rdflicense/allrightsreserved
date published: 2024-08-19
date modified: 2026-07-22T22:24:13Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.117045