Study on the kinetic analysis and pyrolysis evolution in transition zone of metal salt catalyzed steam injection in-situ maoming oil shale upgrading

Abstract

In order to study the kinetic characteristics and pyrolysis evolution in the transition zone of oil shale during metal salt catalyzed steam in-situ production, the oil shale and semi-cokes under different heating conditions were studied by using a self-made reactor and various analysis methods. The results show that the pyrolysis temperature of semi-cokes in the transition zone increases gradually from front to back, the mass loss in the front is greater than that in the back, and the activation energy is less than that in the back. Compared with conventional and steam heating, metal salt catalyzed steam heating enlarges the activation energy difference between the front and back of the transition zone. With the increase in pyrolysis temperature, the aliphatic content in the transition zone decreased rapidly. The front of the transition zone is the main oil and gas generation area, and the oil and gas generation potential in the back is significantly reduced. Metal salt catalyzed steam heating accelerates the pyrolysis and release of aliphatic groups and reduces the degree of aliphatic branching in the transition zone. During the initial pyrolysis, the oxygen-containing functional groups and aromatic structures in the transition zone decreased, and then increased with the increase of pyrolysis temperature. The content of oxygen-containing functional groups in the transition zone of metal salt catalyzed steam heating is generally higher than that of conventional and steam heating, while the content of aromatic structures is generally low, indicating that their interaction increases the oxidation effect, promotes the pyrolysis and release of aromatic structures, and inhibits the condensation of aromatic structures. In the presence of potassium feldspar, the high temperature accelerates the illitization of kaolinite in oil shale, and there is basically no potassium feldspar and pyrite in the back of the transition zone. Compared with metal salt catalysts and steam, temperature is the most important factor affecting the pyrolysis of inorganic minerals in oil shale and semi-cokes.