Contrasting on Hydrocarbon Generation Model and Characteristics of Pyrolysis of Modern Aquatic Plant (Gloeocapsa) vs Marine Animal (Mantis Shrimp)

A hydrocarbon model of the modern aquatic plant Gloeocapsa and the aquatic animal mantis shrimp was found in thermal simulating experiment. The results show that the modern aquatic plant Gloeocapsa is characterized by late generation, late termination and a long duration of oil generation, while the aquatic animal mantis shrimp is characterized by early generation, early termination and a short duration of oil generation. The n-alkanes from Gloeocapsa and mantis shrimp are characterized by peak carbon C₁₅-C₁₇. With increasing thermal simulating temperature, the peak carbon changes from C₁₇ to C₁₅, and the odd-even predominance of n-alkanes becomes less clear. The products from Gloeocapsa contain abundant phenanthrene and naphthalene compounds, and even a little retene, while those from mantis shrimp are dominated by naphthalene compounds, and are poor in phenanthrene compounds. Gloeocapsa and mantis shrimp are rich in C₂₇ sterane, relatively rich in tricyclic terpanes (C₁₉-C₂₉) and hopanes (C₂₇-C₃₅), poor in 5α, 14β, 17β sterane, and coprostane does not disappear until 450℃. The tricyclic terpanes in Gloeocapsa are characterized by peak carbon C₂₃ and C₂₃ > C₂₁, and in mantis shrimp by C₂₁ and C₂₁ > C₂₃. The content of pregnanes is very low at low temperature of thermal simulation, while above 360℃, high levels of pregnane series compounds and even degraded C₂₅ and C₂₆ steranes occur in thermal simulation products.