Chemical reactions are not always at the top of people’s minds, but there’s one we all rely on every day without knowing it: the oxidation of hydrocarbons. Add heat and extra oxygen molecules to hydrocarbons like gasoline and you get combustion, or full oxidation, which powers our airplanes, vehicles, generators and lawnmowers. Add oxygen to natural gas and other petroleum products through immense heat and pressure, and it rearranges their molecular structure through a process of partial oxidation, resulting in the chemical precursors used to make paint, plastic, pharmaceuticals and thousands of other products we encounter every day.
While these oxidation processes are incredibly important to society, they aren’t very well controlled. This leads to the imprecise positioning of atoms in plastic precursors creating pollution from undesired products. Energy extraction from full oxidation reactions is not very efficient either, leading to the loss of huge amounts of energy stored in gasoline.
That’s why Marcel Schreier, the Richard H. Soit Assistant Professor in chemical and biological engineering and an affiliate of the Department of Chemistry at the University of Wisconsin-Madison, will use a National Science Foundation CAREER award to develop methods to finely control the various phases of full and partial oxidation reactions using methods from electrocatalysis, which provide precise control of chemical reaction steps with renewable electricity.
“The dream is to build an “assembly line” that allows us to position atoms in molecules step by step,” says Schreier. “In doing so, we want to open a new kind of manufacturing technology and develop smart chemistry.”
Oxidation is actually a multistep process involving adsorption, oxidation and desorption at the surface of a catalyst. Each of these steps performs best under mutually exclusive conditions, like different temperatures. However, in conventional combustion and chemical production, those differences often cannot easily be taken into account. Instead, raw materials are heated up in the presence of a catalyst and spontaneously form some of the desired end product as well as lots of less desirable compounds. “These reactions are not very discriminate,” says Schreier. “It’s kind of a statistical game, whether the bonds we want form or the bonds we want broken actually break.”
In this project, he and his research group will use methods developed over the last several years to use electricity to optimize the reaction conditions for each step. Then the team will be able to move the hydrocarbons through an electrochemical “conveyer belt,” completing each step separately. This will allow the researchers to combust hydrocarbon fuels more efficiently without creating waste heat and pollutants. The process will also allow them to find ways to transform hydrocarbons into important chemicals with similar efficiency.
If successful, the project could help unlock several new technologies. For instance, it could be used for long-term energy storage if sustainable fuels derived from electricity and captured carbon dioxide could be efficiently transformed back into electricity, creating a closed loop system. The process could also lead to methods to transform chemicals generated from the decomposition of plastics back into partially oxidized plastic precursors, constituting one of the puzzle pieces of a truly sustainable circular economy.
Featured image caption: Marcel Schreier, the Richard H. Soit Assistant Professor in chemical and biological engineering, will use a National Science Foundation CAREER award to develop methods to finely control the various phases of full and partial oxidation reactions using methods from electrocatalysis. Credit: Joel Hallberg.