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Low-temperature oxidation (LTO) is the main reaction that affects fuel formation in the in-situ combustion process, which has important significance for the subsequent combustion propulsion and the successful extraction of crude oil. In this study, heavy oil was subjected to LTO reactions at different temperatures. Three types of reaction products with varying oxidation depths were characterized in terms of the number of oxygen atoms and the polarity of the molecule to reveal the low-temperature oxidation process of the heavy oil. Ketone compounds and acid polyoxides in the oil phase and deep oxidation products with a higher number of oxygen atoms in the coke were identified with increasing oxidation depth. The experimental results showed that the oxidation reaction of the heavy oil changed from kinetic-controlled to diffusion-controlled in the open oxidation system of the heavy oil as the oxidation depth increased. The oxidation reaction of the oil phase reached a maximum and stable value in oxygen content. The molecular compositions of the ketone compound and acid polyoxide did not change significantly with further increase in reaction temperature. The molecular compositions of the deep oxidation products with a higher number of oxygen atoms in the coke phase changed significantly. The coke precursor molecules with a lower oxygen content and condensation degree participated in the coke formation, and the oxidation reaction pathway and the complexity of the oxidation product component also increased. [ABSTRACT FROM AUTHOR]

Steam flooding is a widely used technique to enhance oil recovery of heavy oil. Thermal viscosity reduction and distillation effect are considered as two main displacement mechanisms in steam flooding process. However, the molecular composition understanding and contribution for oil production are still unclear. In this study, the composition analysis of the heavy oil was investigated in the core scale steam flooding process with the temperature from 120 to 280 °C. The crude oil, produced oils and residual oils were characterized comprehensively by gas chromatography and high-resolution mass spectrometry. It is found that steam flooding preferentially extracts aromatics and remains more resins in the residual oil. Viscosity reduction is the dominant mechanism when steam is injected at a low temperature. Large molecular heteroatoms with high carbon number and high double bond equivalent (DBE) are eluted into the produced oil, while compounds with low carbon number and low DBE are remained in the residual oil. As the steam temperature rises, the increased distillation effect results in the extraction of light hydrocarbons from the residual oil to the produced oil. More small heteroatoms with low carbon number and low DBE enter into the produced oil, especially in the none water cut stage. The compositional difference of produced oils is characterized in DBE versus carbon number distribution of the N and O containing compound classes. This work uses a variety of composition analysis methods to clarify the steam flooding mechanism and provides a novel understanding of steam flooding mechanisms with various temperatures and production stages from the molecular perspective. [ABSTRACT FROM AUTHOR]

Propylene is a significant basic material for petrochemicals such as polypropylene, propylene oxide, etc. With abundant propane supply from shale gas, propane dehydrogenation (PDH) becomes extensively attractive as an on-purpose propylene production route in recent years. Nitrogen-doped carbon (NC) nanopolyhedra supported cobalt catalysts were synthesized in one-step of ZIF-67 pyrolysis and investigated further in PDH. XPS, TEM and N2 adsorption-desorption were used to study the influence of carbonization temperature on as-prepared NC supported cobalt catalysts. The temperature is found to affect the cobalt phase and nitrogen species of the catalysts. And the positive correlation was established between Co0 proportion and space time yield of propylene, indicating that the modulation of carbonization temperature could be important for catalytic performance. [ABSTRACT FROM AUTHOR]