If fossil fuels burn completely, the end products are carbon dioxide and water. Today the carbon dioxide is a waste product, one that goes into the air adding to global warming; or the oceans acidifying them; or underground with as yet unknown consequences.
But it's not impossible, says Liviu M. Mirica, PhD, assistant professor of chemistry at Washington University in St. Louis, to drive things the other way, turning carbon dioxide into fuels such as methanol or hydrocarbons.
Until now reversing combustion has been a loser's game, because making carbon dioxide into a fuel uses up more energy than combustion releases and produces more carbon dioxide than it reclaims.
But Mirica thinks catalysts might change everything. Catalysts might provide alternative reaction pathways with lower energy barriers. The reactants could then be bumped over those lower barriers with carbonless energy sources such as sunlight.
Instead of being a polluting one-way street, hydrocarbon chemistry could circle back on itself and become a clean carbon-neutral cycle, although one that still consumed energy.
In the Journal of the American Chemical Society Mirica describes a new metal complex that can combine methyl groups (CH3) in the presence of oxygen to produce ethane (CH3-CH3).
This is the second step in the conversation of methane (CH4), the main component of natural gas, into a longer-chain hydrocarbon, or liquid fuel.
Mirica's team is currently tweaking the complex so that it will be perform the firs step in the methane-to-ethane conversion as well.
The energy problem
Fossil fuels are useful because they pack energy in their chemical bonds and release that energy when they are burned. So they're essentially convenient little energy suitcases.
Reactions that release energy, however, are reluctant to reverse themselves and the more energy they release, the more reluctant they are to
|Contact: Diana Lutz|
Washington University in St. Louis