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Manthiram, Karthish Schiffer, Zachary J Massachusetts Institute of Technology. Department of Chemical Engineering 2022-02-07T15:23:19Z 2022-02-07T15:23:19Z 2021-09 2021-08-12T19:54:45.589Z https://hdl.handle.net/1721.1/140088 0000-0001-6069-8613 Renewable energy sources, such as solar and wind, have become increasingly prevalent and helped drive progress toward decarbonization of electricity. The commodity chemical industry is a large consumer of energy and a major contributor to global greenhouse gas emissions, and electrification of the industry using renewable sources is a possible step toward reducing the carbon footprint of chemicals. In this thesis, I first propose a paradigm where electrochemical systems enable bond-formation steps in the chemical industry, leveraging voltage as an alternative driving force to enable operation at mild temperatures and pressures. I then aim to answer the question “If I can apply mechanical energy (pressure), thermal energy (temperature), or electrical energy (voltage) to a chemical reaction, which should I use?” In particular, I present a universal expression for the equilibrium constant of a chemical reaction as a function of thermodynamic driving forces, and demonstrate how this universal equation and facile visualization of chemical reactions enables quick and informed justification for electrochemical versus thermochemical energy sources. I then focus on the particular case of electrochemical utilization of ammonia, a ubiquitous nitrogen precursor throughout the chemical industry. First, I look at an electrochemical analogue to reductive amination, where a carbonyl group is converted to an amine. Specifically, I demonstrate the electrochemical reductive amination reaction of benzaldehyde and ammonia and investigate its kinetics. I find that the reaction proceeds via an inner-sphere route at heterogeneous metal surfaces, in contrast to most previous work on outer-sphere electrochemical reductive amination systems. I then investigate the kinetics of activating ammonia by breaking the nitrogen-hydrogen bond oxidatively, and I find that the reaction proceeds through an outer-sphere, radical pathway. Last, I propose an energy storage paradigm that leverages ammonium formate, a combination of ammonia and formic acid, to store renewable electricity. I discuss the advantages of this fuel and demonstrate how voltage can aid in the release of energy from this fuel. Overall, in this thesis I start with the broad question of why and when to choose electrochemistry over traditional thermochemical routes in the chemical industry, and I then focus in on how electrochemistry can aid in the utilization of ammonia for both synthesis reactions as well as energy storage purposes. Ph.D. Massachusetts Institute of Technology In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ Kinetic and Thermodynamic Aspects of Voltage as a Driving Force for Ammonia Activation Thesis application/pdf Doctoral Doctor of Philosophy Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="e3f74b0f-8b4f-4957-a1d9-76bad2c4697f"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Title>Kinetic and Thermodynamic Aspects of Voltage as a Driving Force for Ammonia Activation</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2021-09</PublicationDate> <Authors> <Author> <DisplayName>Schiffer, Zachary J</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://rightsstatements.org/page/InC-EDU/1.0/</License> <Abstract>Renewable energy sources, such as solar and wind, have become increasingly prevalent and helped drive progress toward decarbonization of electricity. The commodity chemical industry is a large consumer of energy and a major contributor to global greenhouse gas emissions, and electrification of the industry using renewable sources is a possible step toward reducing the carbon footprint of chemicals. In this thesis, I first propose a paradigm where electrochemical systems enable bond-formation steps in the chemical industry, leveraging voltage as an alternative driving force to enable operation at mild temperatures and pressures. I then aim to answer the question “If I can apply mechanical energy (pressure), thermal energy (temperature), or electrical energy (voltage) to a chemical reaction, which should I use?” In particular, I present a universal expression for the equilibrium constant of a chemical reaction as a function of thermodynamic driving forces, and demonstrate how this universal equation and facile visualization of chemical reactions enables quick and informed justification for electrochemical versus thermochemical energy sources. I then focus on the particular case of electrochemical utilization of ammonia, a ubiquitous nitrogen precursor throughout the chemical industry. First, I look at an electrochemical analogue to reductive amination, where a carbonyl group is converted to an amine. Specifically, I demonstrate the electrochemical reductive amination reaction of benzaldehyde and ammonia and investigate its kinetics. I find that the reaction proceeds via an inner-sphere route at heterogeneous metal surfaces, in contrast to most previous work on outer-sphere electrochemical reductive amination systems. I then investigate the kinetics of activating ammonia by breaking the nitrogen-hydrogen bond oxidatively, and I find that the reaction proceeds through an outer-sphere, radical pathway. Last, I propose an energy storage paradigm that leverages ammonium formate, a combination of ammonia and formic acid, to store renewable electricity. I discuss the advantages of this fuel and demonstrate how voltage can aid in the release of energy from this fuel. Overall, in this thesis I start with the broad question of why and when to choose electrochemistry over traditional thermochemical routes in the chemical industry, and I then focus in on how electrochemistry can aid in the utilization of ammonia for both synthesis reactions as well as energy storage purposes.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>