THE idea that natural gas is formed by thermal decomposition of sedime
ntary organic matter1,2 enjoys almost universal acceptance3-6. But pyr
olysis experiments on organic matter7-13 have failed to reproduce the
composition of natural gas (typically 90% methane). It has recently be
en suggested14 that natural gas may instead be generated catalytically
: transition metals are often found in carbonaceous sedimentary rocks,
and might promote the reaction between hydrogen and n-alkenes (which
are themselves formed during thermal decomposition of kerogen) to give
light hydrocarbons and natural gas. We report here experimental resul
ts that support this hypothesis. In particular, we find that n-alkenes
, hydrogen and a carbonaceous sedimentary rock containing moderately h
igh concentrations of transition metals react under mild conditions (a
pproximately 200-degrees-C) to generate a light-hydrocarbon product in
distinguishable from natural gas in both molecular and carbon isotope
composition. Our results demonstrate that the reaction is indeed catal
ytic, and could alter the way in which we view the generation and dist
ribution of oil and gas in the Earth.