{"id":{"repo_id":"toronto-retro","oai_identifier":"oai:utoronto.scholaris.ca:1807/95884"},"canonical_url":"https://search.dev.ndltd.org/etd/toronto-retro/oai:utoronto.scholaris.ca:1807/95884","repository":{"repo_id":"toronto-retro","name":"University of Toronto","base_url":"https://utoronto.scholaris.ca/server/oai/request"},"display":{"title":"Kinetic Consequences of Surface Oxygen Species during Catalytic C3H6-O2, CO-O2, and COx-H2 Reactions on Transition Metal and Alloy Clusters","abstract":"C3H6 epoxidation, CO oxidation, and COx methanation reactions are important for emission abatement and value-added compound production. They occur on transition metal/alloy clusters via the kinetic coupling of steps that involve activation of carbon containing reactants (C3H6, COx) with co-reactants. The reaction mechanisms for each of these processes involve partial or total oxidations of reactants with distinct reactive oxidants. Kinetic and isotopic measurements, micro-kinetic modelling, and titration experiments reveal the mechanistic similarities between these seemingly different reaction systems, despite their distinctly different operating conditions and types of surface reactive oxygen species. For the first case of C3H6-O2 reactions, competitive epoxidation and combustion reactions occur on Ag clusters predominantly covered by O*. The desired epoxidation occurs via reactions between O* and C3H6. Contrarily, the undesired combustion to COx and H2O involves C-H bond cleavage by OOH*, which forms auto-catalytically from O2 and H2O. For the second case of CO oxidation, which is a step within C3H6 combustion, reactions between O2* and CO* take place on Ag and Group VIII metal cluster surfaces saturated with reactive O* or CO*. Here, the reactant ratios, reaction temperature, and the O* and CO* heats of adsorption on surfaces determine the O* and CO* coverages. While O* is much more abundant, O2* is the more reactive oxidant for CO oxidation. For the third case of COx methanation, a hydrogenation, the reaction occurs via the transfer of hydrogen from OH* to CH3* on Co and Ni-Co clusters partially covered with O* and via transfer of hydrogen from H* to CH3* on Ni and Ni-Co clusters partially covered with C*. The reaction conditions and metal affinities to O* and C* determine the competing adsorbate coverages. The competing coverages of reactive species lead to complex rate expressions that depend on the reaction temperature and inlet gas compositions. Simultaneously, the catalyst metal identity and average cluster diameters alter the heats of adsorption of the surface species and vary their reactivities and coverages. This study connects these kinetic and thermodynamic consequences across three catalytic processes and derives the expressions for these trends, allowing for reactor designs that optimize desired product yields.","abstract_html":"C3H6 epoxidation, CO oxidation, and COx methanation reactions are important for emission abatement and value-added compound production. They occur on transition metal/alloy clusters via the kinetic coupling of steps that involve activation of carbon containing reactants (C3H6, COx) with co-reactants. The reaction mechanisms for each of these processes involve partial or total oxidations of reactants with distinct reactive oxidants. Kinetic and isotopic measurements, micro-kinetic modelling, and titration experiments reveal the mechanistic similarities between these seemingly different reaction systems, despite their distinctly different operating conditions and types of surface reactive oxygen species. For the first case of C3H6-O2 reactions, competitive epoxidation and combustion reactions occur on Ag clusters predominantly covered by O*. The desired epoxidation occurs via reactions between O* and C3H6. Contrarily, the undesired combustion to COx and H2O involves C-H bond cleavage by OOH*, which forms auto-catalytically from O2 and H2O. For the second case of CO oxidation, which is a step within C3H6 combustion, reactions between O2* and CO* take place on Ag and Group VIII metal cluster surfaces saturated with reactive O* or CO*. Here, the reactant ratios, reaction temperature, and the O* and CO* heats of adsorption on surfaces determine the O* and CO* coverages. While O* is much more abundant, O2* is the more reactive oxidant for CO oxidation. For the third case of COx methanation, a hydrogenation, the reaction occurs via the transfer of hydrogen from OH* to CH3* on Co and Ni-Co clusters partially covered with O* and via transfer of hydrogen from H* to CH3* on Ni and Ni-Co clusters partially covered with C*. The reaction conditions and metal affinities to O* and C* determine the competing adsorbate coverages. The competing coverages of reactive species lead to complex rate expressions that depend on the reaction temperature and inlet gas compositions. Simultaneously, the catalyst metal identity and average cluster diameters alter the heats of adsorption of the surface species and vary their reactivities and coverages. This study connects these kinetic and thermodynamic consequences across three catalytic processes and derives the expressions for these trends, allowing for reactor designs that optimize desired product yields.","abstract_has_math":false,"creators":["Lachkov, Petar T"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Chemical Engineering Applied Chemistry","school":null,"contributors":[],"advisors":["Chin, Ya-Huei C"],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-06","date_published":"2019-06","updated_at":"2026-07-27T21:27:56Z","subjects":["Catalysis","DFT","Kinetics","Methanation","Oxidation","Thermodynamics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1807/95884","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Chin, Ya-Huei C"]},{"key":"dc:contributor.department","label":"Department","values":["Chemical Engineering Applied Chemistry"]},{"key":"dc:creator","label":"Author","values":["Lachkov, Petar T"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-06"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2019-07-23T17:00:14Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2019-07-23T17:00:14Z"]},{"key":"dc:date.issued","label":"Date","values":["2019-06"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Catalysis","DFT","Kinetics","Methanation","Oxidation","Thermodynamics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1807/95884"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["C3H6 epoxidation, CO oxidation, and COx methanation reactions are important for emission abatement and value-added compound production. They occur on transition metal/alloy clusters via the kinetic coupling of steps that involve activation of carbon containing reactants (C3H6, COx) with co-reactants. The reaction mechanisms for each of these processes involve partial or total oxidations of reactants with distinct reactive oxidants. Kinetic and isotopic measurements, micro-kinetic modelling, and titration experiments reveal the mechanistic similarities between these seemingly different reaction systems, despite their distinctly different operating conditions and types of surface reactive oxygen species. For the first case of C3H6-O2 reactions, competitive epoxidation and combustion reactions occur on Ag clusters predominantly covered by O*. The desired epoxidation occurs via reactions between O* and C3H6. Contrarily, the undesired combustion to COx and H2O involves C-H bond cleavage by OOH*, which forms auto-catalytically from O2 and H2O. For the second case of CO oxidation, which is a step within C3H6 combustion, reactions between O2* and CO* take place on Ag and Group VIII metal cluster surfaces saturated with reactive O* or CO*. Here, the reactant ratios, reaction temperature, and the O* and CO* heats of adsorption on surfaces determine the O* and CO* coverages. While O* is much more abundant, O2* is the more reactive oxidant for CO oxidation. For the third case of COx methanation, a hydrogenation, the reaction occurs via the transfer of hydrogen from OH* to CH3* on Co and Ni-Co clusters partially covered with O* and via transfer of hydrogen from H* to CH3* on Ni and Ni-Co clusters partially covered with C*. The reaction conditions and metal affinities to O* and C* determine the competing adsorbate coverages. The competing coverages of reactive species lead to complex rate expressions that depend on the reaction temperature and inlet gas compositions. Simultaneously, the catalyst metal identity and average cluster diameters alter the heats of adsorption of the surface species and vary their reactivities and coverages. This study connects these kinetic and thermodynamic consequences across three catalytic processes and derives the expressions for these trends, allowing for reactor designs that optimize desired product yields."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Kinetic Consequences of Surface Oxygen Species during Catalytic C3H6-O2, CO-O2, and COx-H2 Reactions on Transition Metal and Alloy Clusters"]}]}],"canonical_facts":{"dc:contributor.advisor":["Chin, Ya-Huei C"],"dc:contributor.department":["Chemical Engineering Applied Chemistry"],"dc:creator":["Lachkov, Petar T"],"dc:date":["2019-06"],"dc:date.accessioned":["2019-07-23T17:00:14Z"],"dc:date.available":["2019-07-23T17:00:14Z"],"dc:date.issued":["2019-06"],"dc:description.abstract":["C3H6 epoxidation, CO oxidation, and COx methanation reactions are important for emission abatement and value-added compound production. They occur on transition metal/alloy clusters via the kinetic coupling of steps that involve activation of carbon containing reactants (C3H6, COx) with co-reactants. The reaction mechanisms for each of these processes involve partial or total oxidations of reactants with distinct reactive oxidants. Kinetic and isotopic measurements, micro-kinetic modelling, and titration experiments reveal the mechanistic similarities between these seemingly different reaction systems, despite their distinctly different operating conditions and types of surface reactive oxygen species. For the first case of C3H6-O2 reactions, competitive epoxidation and combustion reactions occur on Ag clusters predominantly covered by O*. The desired epoxidation occurs via reactions between O* and C3H6. Contrarily, the undesired combustion to COx and H2O involves C-H bond cleavage by OOH*, which forms auto-catalytically from O2 and H2O. For the second case of CO oxidation, which is a step within C3H6 combustion, reactions between O2* and CO* take place on Ag and Group VIII metal cluster surfaces saturated with reactive O* or CO*. Here, the reactant ratios, reaction temperature, and the O* and CO* heats of adsorption on surfaces determine the O* and CO* coverages. While O* is much more abundant, O2* is the more reactive oxidant for CO oxidation. For the third case of COx methanation, a hydrogenation, the reaction occurs via the transfer of hydrogen from OH* to CH3* on Co and Ni-Co clusters partially covered with O* and via transfer of hydrogen from H* to CH3* on Ni and Ni-Co clusters partially covered with C*. The reaction conditions and metal affinities to O* and C* determine the competing adsorbate coverages. The competing coverages of reactive species lead to complex rate expressions that depend on the reaction temperature and inlet gas compositions. Simultaneously, the catalyst metal identity and average cluster diameters alter the heats of adsorption of the surface species and vary their reactivities and coverages. This study connects these kinetic and thermodynamic consequences across three catalytic processes and derives the expressions for these trends, allowing for reactor designs that optimize desired product yields."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["http://hdl.handle.net/1807/95884"],"dc:subject":["Catalysis","DFT","Kinetics","Methanation","Oxidation","Thermodynamics"],"dc:title":["Kinetic Consequences of Surface Oxygen Species during Catalytic C3H6-O2, CO-O2, and COx-H2 Reactions on Transition Metal and Alloy Clusters"],"dc:type":["Thesis"]},"updated_at":"2026-07-27T21:27:56Z"}