Science has found a new catalyst for the combustion of methane – but why is this important?
The new material shows an activity 30 times greater than any catalysts previously tested, and the use of this more-active catalyst could lead to a more efficient generation of energy from methane combustion, and a decrease in emissions of hazardous substances and greenhouse gases.
Methane As Alternative to Oil-Based Fuel
Methane (CH4) is a gaseous molecule, the main component of natural gas. Methane is widely used as a fuel; in fact, it can react with molecular oxygen (O2) to generate energy, according to the reaction:
CH4 + 2 O2 → CO2 + 2 H2O
If compared with other fuels (i.e. oil and its derivatives) methane presents several advantages.
In the first place, methane is relatively abundant on Earth, with reserves greater than the known oil reserves. In addition, methane combustion is a cleaner process because, in comparison with oil, less carbon dioxide is produced for the same amount of heat generated. Considering carbon dioxide’s greenhouse properties, and their possible effects on global warming, using methane as a fuel could be less harmful for the environment.
Methane as Energy Source: Possible Problems
Using methane to generate energy, however, can present some problems.
Due to its simple structure, it is a very stable molecule, so it takes more energy to break the bonds between the atoms and initiate the combustion reaction. Consequently, it’s necessary to perform the combustion at high temperatures, i.e. more than 800 oC.
Further to the costs associated with the combustion process, the use of such high temperatures also favors the formation of hazardous molecules. Oxygen can, in fact, react with the nitrogen (N2) present in the atmosphere, to form several nitrogen oxides (NOx, x = 1-2); these species are acidic, and can affect both human health (causing irritation and respiratory problems) and the environment (causing acid rain).
Another possible risk associated withmethane use is its incomplete combustion: if the methane does not react completely, it will be emitted into the atmosphere. This can be a problem, as methane is a very powerful greenhouse gas, about 20 times more effective than carbon dioxide.
Methane Combustion: Catalysts to Decrease Temperature
Catalysts are molecules which can accelerate a reaction, and make it easier for the reaction to take place. Scientists have considered the use of catalysts for the combustion of methane, and several studies were performed to develop a material appropriate for this reaction, but many problems were encountered during the course of the studies. For example, most catalysts were not very active at temperatures lower than 400 oC, but at higher temperatures the catalysts were damaged and had no effect at all.
Significant progress in this field, however, was made recently by researchers of the Materials, Environment and Energy Research Group, of Trieste University (Italy) and the National Council of Research (CNR). The research was done in cooperation with the Faculty of Sciences of Cádiz University (Spain) and the Department of Chemical and Biomolecular Engineering of University of Pennsylvania (United States).
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