The work targets olefin epoxidation, a reaction that currently relies on harsh peroxides as oxidants. These peroxides are difficult to dispose of safely and generate carbon dioxide, adding to the environmental footprint of epoxide production.
Water can serve as a cleaner oxidant, but its strong H2O bonds make it difficult to activate, so conventional water based epoxidation demands high temperature conditions that require large energy inputs and further increase CO2 emissions.
A team led by chemistry professor Prashant Jain at the University of Illinois Urbana-Champaign has turned to plasmonic chemistry, using light to drive electrochemical reactions, to overcome these limitations. Jain's group is known for using solar energy in plasmon assisted processes, including recycling inorganic carbon dioxide into chemical fuels.
In the new study, published in the Journal of the American Chemical Society, the researchers applied light enhanced electrochemistry to epoxidation reactions using water as the oxidant. They hypothesized that the same principles that had worked for ammonia synthesis and CO2 reduction could extend to this industrially important chemistry.
A central advance in the work, led by Illinois researcher Lucas Germano, is the design of light absorbing "antenna" catalysts that pair gold nanoparticles with manganese oxide nanowire electrodes. This architecture combines electrical bias with visible light photons to break the H O H bonds in water under much milder conditions than conventional high temperature reactors.
When illuminated with laboratory scale lasers, the gold nanoparticles absorb visible light and generate strong local electric fields and energetic charge carriers. According to Jain, these fields weaken both the O H bonds in water and the carbon carbon double bond in styrene, the olefin used in the experiments.
Under these conditions, oxygen atoms can be extracted from H2O and inserted across the carbon carbon double bond to form an epoxide, turning water into an effective oxidant. The reaction proceeds at lower thermal load, avoiding the harsh peroxides typically used and opening a path to lower carbon epoxide production.
The authors note that their current results come from lab scale demonstrations, and moving to industrial scale will pose several engineering challenges. One priority is replacing the laser light sources with scalable, energy efficient illumination that can be powered by sunlight or high efficiency LEDs.
Another challenge is to fine tune the light driven reaction pathways to minimize overoxidation and unwanted side products. The team also aims to design large, light accessible electrolyzer systems that can translate the activity observed in small reactors to volumes relevant for manufacturing.
Research Report:Plasmon-assisted electrochemical epoxidation using water as an oxidant
Related Links
University of Illinois Urbana-Champaign
Space Technology News - Applications and Research
| Subscribe Free To Our Daily Newsletters |
| Subscribe Free To Our Daily Newsletters |
