Engineers Seek Ways to Convert Methane Into Useful Chemicals
12/20/2012 - University of Virginia - Little more
than a decade ago, the United States imported much of its natural
Today, the nation is tapping into its own natural gas reserves
and producing enough to support most of its current needs for
heating and power generation, and is beginning to export natural gas
to other countries.
The trend is expected to continue, as new methods are developed to
extract natural gas from vast unrecovered reserves embedded in
shale. Natural gas can be used to generate electricity, and it burns
cleaner than coal.
“With petroleum reserves in decline, natural gas production is
destined to increase to help meet worldwide energy demands,” said
Matthew Neurock, a chemical engineering professor in the University
of Virginia’s School of Engineering and Applied Science.
petroleum – in addition to being used to make fuels – is also used
to make ethylene, propylene and other building blocks used in the
production of a wide range of other chemicals.
We need to develop
innovative processes that can readily make these chemical
intermediates from natural gas.”
The problem is, there currently are no cost-effective ways to do
Methane, the principal component of natural gas, is rather
inert and requires high temperatures to activate its strong chemical
bonds; therefore the practical and successful conversion of methane
to useful chemical intermediates has thus far eluded chemists and
Neurock is working with colleagues at Northwestern University to
invent novel ways and catalytic materials to activate methane to
This week the collaborators published a paper in
the online edition of the journal Nature Chemistry detailing the use
of sulfur as a possible “soft” oxidant for catalytically converting
methane into ethylene, a key “intermediate” for making chemicals,
polymers, fuels and, ultimately, products such as films,
surfactants, detergents, antifreeze, textiles and others.
“We show, through both theory – using quantum mechanical
calculations – and laboratory experiments, that sulfur can be used
together with novel sulfide catalysts to convert methane to
ethylene, an important intermediate in the production of a wide
range of materials,” Neurock said.
Chemists and engineers have attempted to develop catalysts and
catalytic processes that use oxygen to make ethylene, methanol and
other intermediates, but have had little success as oxygen is too
reactive and tends to over-oxidize methane to common carbon dioxide.
Neurock said that sulfur or other “softer” oxidants that have weaker
affinities for hydrogen may be the answer, in that they can help to
limit the over-reaction of methane to carbon disulfide.
team’s process, methane is reacted with sulfur over sulfide
catalysts used in petroleum processes.
Sulfur is used to remove
hydrogen from the methane to form hydrocarbon fragments, which
subsequently react together on the catalyst to form ethylene.
Theoretical and experimental results indicate that the conversion of
methane and the selectivity to produce ethylene are controlled by
how strong the sulfur bonds to the catalyst.
Using these concepts,
the team explored different metal sulfide catalysts to ultimately
tune the metal-sulfur bond strength in order to control the
conversion of methane to ethylene.
Chemical companies consider methane a particularly attractive raw
material because of the large reserves of natural gas in the U.S.
and other parts of the world.
In 2007, Dow issued a “Methane Challenge,” seeking revolutionary
chemical processes to facilitate the conversion of methane to
ethylene and other useful chemicals.
The company received about 100
proposals from universities, institutes and companies around the
In 2008, the company awarded major research grants to Cardiff
University and Northwestern University to advance the quest.
is a member of the Northwestern University team.
He is using
theoretical methods and high-performance computing to understand the
processes that control catalysis and to guide the experimental
research at Northwestern.
“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,” Neurock said.
“Our finding – of using sulfur to catalyze 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.”
Neurock’s co-investigators on the Nature Chemistry paper are Qingjun
Zhu, Staci Wegener, Chao Xie and Tobin Marks of Northwestern
University, and U.Va. colleague Obioma Uche.