Composition of Closed-System Fischer-Tropsch Synthesis Gases and the Constraint Factors

Biogenic gases were reported to exhibit a ‘‘normal’’ carbon isotope order, whereas abiogenic gaseous hydrocarbons in igneous rocks and meteorites exhibit a reversed order. In this study, closed-system Fischer–Tropsch synthesis was conducted at 350°C and 380°C under 30 MPa and 390°C under 30, 100, and 200 MPa, respectively, with magnetite as a catalyst. The results do not show an expected reversed order, even though the features of partially reversed order in carbon isotope values can still be commonly observed. Studies have shown that the essential constraint factor on the carbon isotopic pattern of abiogenic gases is the molar ratio of H2/CO2.