Transition metal catalysis in the generation of natural gas

Carbonaceous sedimentary rocks containing transition metals are known to be catalytic in the conversion of hydrogen and n-alkenes into natural gas, but the source of activity is unclear. The evidence presented here supports transition metals as the active agents. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalytically robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process: The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60–95 + wt% methane), while gas generated thermally is consistently depleted in methane (10–60 wt% methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.