CO2 corrosion of mild steel in the oil and gas industry has been widely investigated. Nevertheless, research on high temperature CO2 corrosion has been rarely conducted, and its mechanisms remain unclear. Therefore, it is important to complete an in-depth study of CO2 corrosion of mild steel at high temperature. The entire scope of this Ph.D. research is to investigate and model CO2 corrosion of mild steel over a range of 25-250¿¿C. The research is divided into four main sections: chemical thermodynamics, electrochemical thermodynamics, electrochemical kinetics, and the proposal of mechanisms of CO2 corrosion.
In the chemical thermodynamics segment, water chemistry components of CO2 systems were studied. In the absence of Fe2+, pH increased with temperature in both predicted and experimental results. With addition of Fe2+, pH did not change with temperature due to FeCO3 precipitation.
Pourbaix diagrams for the Fe-CO2-H2O systems were constructed using thermodynamic theory and data, subsequently validated with observed CO2 corrosion phenomena. In the range of 80-150¿¿C, FeCO3 and Fe2(OH)2CO3 formed on the steel surface, for experiments lasting 4 days. At 200-250¿¿C, the corrosion product was exclusively Fe3O4. Kinetic studies conducted at 120¿¿C show full transformation from plate-like Fe2(OH)2CO3 to oblong prismatic FeCO3 crystals over time. In relation to pressure effects, FeCO3 is the more favored corrosion product than Fe3O4 at high pCO2. With surface pH consideration, the generated Pourbaix diagrams were validated by experimental results.
The corrosion kinetic experiments at elevated temperatures were further investigated including the effects of pH and flow. It was concluded that corrosion rates did not monotonously decrease with temperatures due to formation of corrosion products. Corrosion rates at pH 4.0 were higher than those at pH 6.0, independent of temperature. The main corrosion product was FeCO3 with Fe3O4 present at temperatures above 150¿¿C. No flow sensitivity was observed due to the formation of corrosion products.
Mechanisms of CO2 corrosion at temperatures of 25-250¿¿C were proposed based on the current CO2 corrosion model with an addition of Fe3O4 formation. The thermodynamics and kinetics of Fe3O4 formation were identified. As soon as thermodynamic conditions for Fe3O4 are achieved, it forms and protects the steel.
","abstract_html":"<p>CO<sub>2</sub> corrosion of mild steel in the oil and gas industry has been widely investigated. Nevertheless, research on high temperature CO<sub>2</sub> corrosion has been rarely conducted, and its mechanisms remain unclear. Therefore, it is important to complete an in-depth study of CO<sub>2</sub> corrosion of mild steel at high temperature. The entire scope of this Ph.D. research is to investigate and model CO<sub>2</sub> corrosion of mild steel over a range of 25-250¿¿C. The research is divided into four main sections: chemical thermodynamics, electrochemical thermodynamics, electrochemical kinetics, and the proposal of mechanisms of CO<sub>2</sub> corrosion. </p><p>In the chemical thermodynamics segment, water chemistry components of CO<sub>2</sub> systems were studied. In the absence of Fe2+, pH increased with temperature in both predicted and experimental results. With addition of Fe2+, pH did not change with temperature due to FeCO<sub>3</sub> precipitation.</p><p>Pourbaix diagrams for the Fe-CO<sub>2</sub>-H<sub>2</sub>O systems were constructed using thermodynamic theory and data, subsequently validated with observed CO<sub>2</sub> corrosion phenomena. In the range of 80-150¿¿C, FeCO<sub>3</sub> and Fe<sub>2</sub>(OH)<sub>2</sub>CO<sub>3</sub> formed on the steel surface, for experiments lasting 4 days. At 200-250¿¿C, the corrosion product was exclusively Fe3O4. Kinetic studies conducted at 120¿¿C show full transformation from plate-like Fe<sub>2</sub>(OH)<sub>2</sub>CO<sub>3</sub> to oblong prismatic FeCO<sub>3</sub> crystals over time. In relation to pressure effects, FeCO<sub>3</sub> is the more favored corrosion product than Fe<sub>3</sub>O<sub>4</sub> at high pCO<sub>2</sub>. With surface pH consideration, the generated Pourbaix diagrams were validated by experimental results.</p><p>The corrosion kinetic experiments at elevated temperatures were further investigated including the effects of pH and flow. It was concluded that corrosion rates did not monotonously decrease with temperatures due to formation of corrosion products. Corrosion rates at pH 4.0 were higher than those at pH 6.0, independent of temperature. The main corrosion product was FeCO<sub>3</sub> with Fe<sub>3</sub>O<sub>4</sub> present at temperatures above 150¿¿C. No flow sensitivity was observed due to the formation of corrosion products.</p><p>Mechanisms of CO<sub>2</sub> corrosion at temperatures of 25-250¿¿C were proposed based on the current CO<sub>2</sub> corrosion model with an addition of Fe<sub>3</sub>O<sub>4</sub> formation. The thermodynamics and kinetics of Fe<sub>3</sub>O<sub>4</sub> formation were identified. As soon as thermodynamic conditions for Fe<sub>3</sub>O<sub>4</sub> are achieved, it forms and protects the steel.</p>","abstract_has_math":false,"creators":["Tanupabrungsun, Tanaporn"],"institution":"Ohio University","degree_name":"Doctor of Philosophy (PhD)","degree_level":"doctoral","degree_discipline":"Chemical Engineering (Engineering and Technology)","degree_department":null,"school":null,"contributors":["Nesic, Srdjan"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012","date_published":"2012","updated_at":"2026-07-24T03:36:08Z","subjects":["Chemical Engineering","Engineering","CO2 corrosion mechanism","mild steel","elevation temperature","pourbaix diagram","thermodynamics","kinetics"],"languages":["English"],"rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1355328679","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Nesic, Srdjan"]},{"key":"dc:creator","label":"Author","values":["Tanupabrungsun, Tanaporn"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012"]},{"key":"dc:publisher","label":"Institution","values":["Ohio University / OhioLINK"]},{"key":"dc:type","label":"Dc Type","values":["Electronic Thesis or Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemical Engineering (Engineering and Technology)"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Ohio University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Chemical Engineering","Engineering","CO2 corrosion mechanism","mild steel","elevation temperature","pourbaix diagram","thermodynamics","kinetics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1355328679"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["CO2 corrosion of mild steel in the oil and gas industry has been widely investigated. Nevertheless, research on high temperature CO2 corrosion has been rarely conducted, and its mechanisms remain unclear. Therefore, it is important to complete an in-depth study of CO2 corrosion of mild steel at high temperature. The entire scope of this Ph.D. research is to investigate and model CO2 corrosion of mild steel over a range of 25-250¿¿C. The research is divided into four main sections: chemical thermodynamics, electrochemical thermodynamics, electrochemical kinetics, and the proposal of mechanisms of CO2 corrosion.
In the chemical thermodynamics segment, water chemistry components of CO2 systems were studied. In the absence of Fe2+, pH increased with temperature in both predicted and experimental results. With addition of Fe2+, pH did not change with temperature due to FeCO3 precipitation.
Pourbaix diagrams for the Fe-CO2-H2O systems were constructed using thermodynamic theory and data, subsequently validated with observed CO2 corrosion phenomena. In the range of 80-150¿¿C, FeCO3 and Fe2(OH)2CO3 formed on the steel surface, for experiments lasting 4 days. At 200-250¿¿C, the corrosion product was exclusively Fe3O4. Kinetic studies conducted at 120¿¿C show full transformation from plate-like Fe2(OH)2CO3 to oblong prismatic FeCO3 crystals over time. In relation to pressure effects, FeCO3 is the more favored corrosion product than Fe3O4 at high pCO2. With surface pH consideration, the generated Pourbaix diagrams were validated by experimental results.
The corrosion kinetic experiments at elevated temperatures were further investigated including the effects of pH and flow. It was concluded that corrosion rates did not monotonously decrease with temperatures due to formation of corrosion products. Corrosion rates at pH 4.0 were higher than those at pH 6.0, independent of temperature. The main corrosion product was FeCO3 with Fe3O4 present at temperatures above 150¿¿C. No flow sensitivity was observed due to the formation of corrosion products.
Mechanisms of CO2 corrosion at temperatures of 25-250¿¿C were proposed based on the current CO2 corrosion model with an addition of Fe3O4 formation. The thermodynamics and kinetics of Fe3O4 formation were identified. As soon as thermodynamic conditions for Fe3O4 are achieved, it forms and protects the steel.
"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf","p.187","9.68 MB"]},{"key":"dc:title","label":"Title","values":["Thermodynamics and Kinetics of Carbon Dioxide Corrosion of Mild Steel at Elevated Temperatures"]}]}],"canonical_facts":{"dc:contributor":["Nesic, Srdjan"],"dc:creator":["Tanupabrungsun, Tanaporn"],"dc:date":["2012"],"dc:description":["CO2 corrosion of mild steel in the oil and gas industry has been widely investigated. Nevertheless, research on high temperature CO2 corrosion has been rarely conducted, and its mechanisms remain unclear. Therefore, it is important to complete an in-depth study of CO2 corrosion of mild steel at high temperature. The entire scope of this Ph.D. research is to investigate and model CO2 corrosion of mild steel over a range of 25-250¿¿C. The research is divided into four main sections: chemical thermodynamics, electrochemical thermodynamics, electrochemical kinetics, and the proposal of mechanisms of CO2 corrosion.
In the chemical thermodynamics segment, water chemistry components of CO2 systems were studied. In the absence of Fe2+, pH increased with temperature in both predicted and experimental results. With addition of Fe2+, pH did not change with temperature due to FeCO3 precipitation.
Pourbaix diagrams for the Fe-CO2-H2O systems were constructed using thermodynamic theory and data, subsequently validated with observed CO2 corrosion phenomena. In the range of 80-150¿¿C, FeCO3 and Fe2(OH)2CO3 formed on the steel surface, for experiments lasting 4 days. At 200-250¿¿C, the corrosion product was exclusively Fe3O4. Kinetic studies conducted at 120¿¿C show full transformation from plate-like Fe2(OH)2CO3 to oblong prismatic FeCO3 crystals over time. In relation to pressure effects, FeCO3 is the more favored corrosion product than Fe3O4 at high pCO2. With surface pH consideration, the generated Pourbaix diagrams were validated by experimental results.
The corrosion kinetic experiments at elevated temperatures were further investigated including the effects of pH and flow. It was concluded that corrosion rates did not monotonously decrease with temperatures due to formation of corrosion products. Corrosion rates at pH 4.0 were higher than those at pH 6.0, independent of temperature. The main corrosion product was FeCO3 with Fe3O4 present at temperatures above 150¿¿C. No flow sensitivity was observed due to the formation of corrosion products.
Mechanisms of CO2 corrosion at temperatures of 25-250¿¿C were proposed based on the current CO2 corrosion model with an addition of Fe3O4 formation. The thermodynamics and kinetics of Fe3O4 formation were identified. As soon as thermodynamic conditions for Fe3O4 are achieved, it forms and protects the steel.
"],"dc:format":["application/pdf","p.187","9.68 MB"],"dc:identifier":["http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1355328679"],"dc:language":["English"],"dc:publisher":["Ohio University / OhioLINK"],"dc:rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"dc:subject":["Chemical Engineering","Engineering","CO2 corrosion mechanism","mild steel","elevation temperature","pourbaix diagram","thermodynamics","kinetics"],"dc:title":["Thermodynamics and Kinetics of Carbon Dioxide Corrosion of Mild Steel at Elevated Temperatures"],"dc:type":["Electronic Thesis or Dissertation"],"thesis:degree_discipline":["Chemical Engineering (Engineering and Technology)"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Doctor of Philosophy (PhD)"],"thesis:institution_name":["Ohio University"]},"updated_at":"2026-07-24T03:36:08Z"}