Methane could be used to make ethylene, a precursor of polymers, fuels, surfactants and detergents
21/12/2012
Sulphur offers path to chemicals from methane
Could lead to greater exploitation of cheap shale
Helen Tunnicliffe
CATALYSTS based on sulphur could be used to convert methane in natural gas into ethylene, a precursor of many important chemicals, according to US-based chemical engineers.
In the US, shale gas is providing a cheap and readily available source of methane, so finding easy ways of converting it into ethylene, used to make polymers, fuels, surfactants, detergents, and textiles, amongst others, could offer a new source of revenue to chemicals companies. Methane usually requires very high temperatures to activate its chemical bonds and react it, and there have been many attempts to find catalysts to make this process easier. Matthew Neurock, a chemical engineering professor at the University of Virginia’s School of Engineering and Applied Science, thinks that using elemental sulphur and sulphide catalysts could provide the answer.
Neurock and colleagues at Northwestern University used quantum mechanical calculations to prove the theory of their idea, and laboratory experiments to prove the practical aspects.
Previous experiments had attempted to use oxygen as a catalyst, but found that oxygen is too reactive, producing carbon dioxide rather than ethylene. The sulphur reacts with the hydrogen, removing it from the methane. The resulting hydrocarbon fragments can then react on the sulphide catalyst, forming longer chain hydrocarbons, like ethylene. The researchers believe that sulphur has a lower affinity for the hydrogen, which prevents over-reaction. A high methane:sulphur ratio and the availability of a support increases the selectivity to produce ethylene.
“The abundance of natural gas, along with the development of new methods to extract it from hidden reserves, offers unique opportunities for the development of catalytic processes that can convert methane to chemicals,” says Neurock. “Our finding – of using sulphur to catalyse the conversion of methane to ethylene – shows initial promise for the development of new catalytic processes that can potentially take full advantage of these reserves. The research, however, is really just in its infancy.”
Nature Chemistry DOI: 10.1038/nchem.1527