While methane is less abundant than carbon dioxide, its impact on global warming is significant, as it traps more heat in the atmosphere due to its molecular structure.
Now, MIT chemical engineers have developed a catalyst capable of transforming methane into valuable polymers, aiming to mitigate greenhouse gas emissions.
The innovative catalyst operates at room temperature and normal atmospheric pressure, potentially simplifying and reducing costs for its application at methane production sites, including power plants and livestock facilities.
At the molecular level, methane consists of one carbon atom linked to four hydrogen atoms. Ideally, this molecule could serve as an effective foundation for producing valuable items like polymers. Yet, the challenge lies in converting methane into other compounds, which traditionally demand high temperatures and pressures.
To overcome this energy hurdle, the MIT team developed a hybrid catalyst combining two components: a zeolite and a naturally occurring enzyme. Zeolites are plentiful, cost-effective minerals known for their catalytic abilities, particularly in transforming methane into carbon dioxide.
In their study, the researchers used a specific zeolite known as iron-modified aluminum silicate, alongside an enzyme called alcohol oxidase. This enzyme is utilized by bacteria, fungi, and plants to oxidize alcohols.
The hybrid catalyst operates through a two-step reaction. Initially, the zeolite transforms methane into methanol, followed by the enzyme converting methanol into formaldehyde. This process also produces hydrogen peroxide, which is then reintegrated into the zeolite, providing a source of oxygen for the methane to methanol conversion.
This sequence of reactions can take place at room temperature without the need for high pressure. The catalyst particles are suspended in water, allowing them to absorb methane from the air around them. For potential future uses, the researchers envision that it could be applied as a coating on surfaces.
“Other systems operate at high temperatures and high pressures, and they use hydrogen peroxide, which is an expensive chemical, to drive methane oxidation. But our enzyme produces hydrogen peroxide from oxygen, so I think our system could be very cost-effective and scalable,” said MIT postdoc Jimin Kim.
Damien Debecker, a professor at the Institute of Condensed Matter and Nanosciences at the University of Louvain, Belgium, highlights that creating a system that incorporates both enzymes and artificial catalysts is a “smart strategy.”
“Combining these two families of catalysts is challenging, as they tend to operate in rather distinct operation conditions. By unlocking this constraint and mastering the art of chemo-enzymatic cooperation, hybrid catalysis becomes key-enabling: It opens new perspectives to run complex reaction systems in an intensified way,” says Debecker, who was not involved in the research.
After the production of formaldehyde, the researchers demonstrated that this molecule could be utilized to create polymers by incorporating urea, a nitrogen-rich compound found in urine. This resin-like polymer, called urea-formaldehyde, is already making waves in various industries and is being utilized in products such as particle boards and textiles.
The researchers envision that this catalyst could be incorporated into pipes used to transport natural gas. Within those pipes, the catalyst could generate a polymer that could act as a sealant to heal cracks in the pipes, which are a common source of methane leakage.
Additionally, this catalyst could be applied as a protective film on surfaces exposed to methane gas, allowing for the collection of polymers that can be repurposed for manufacturing.
Lead researcher Michael Strano’s lab is now working on catalysts that could be used to remove carbon dioxide from the atmosphere and combine it with nitrate to produce urea. This urea can then be utilized alongside the formaldehyde created by the zeolite-enzyme catalyst, leading to the production of even more urea-formaldehyde.
Journal reference:
- Daniel J. Lundberg, Jimin Kim, Yu-Ming Tu, Cody L. Ritt & Michael S. Strano. Concerted methane fixation at ambient temperature and pressure mediated by an alcohol oxidase and Fe-ZSM-5 catalytic couple. Nature Catalysis, 2024; DOI: 10.1038/s41929-024-01251-z