Characterization of the oil shale products derived via topochemical reaction method

•A topochemical reaction method was studied for shale oil and gas extraction.•The mechanism of topochemical reaction was proposed and well demonstrated.•The oxygen is a crucial factor for this chemical heat-enhanced procedure.•There were five distinct reaction identified in entire process. In this study, the topochemical reaction strategy, utilizing Huadian oil shale to produce shale gas, liquid, and solid residues, has been demonstrated. Thermogravimetric analysis, Fourier transform-infrared spectroscopy, X-ray diffraction, gas chromatography–mass spectrometry, and scanning electron microscopy were performed to characterize the products obtained at different temperatures. Furthermore, the mechanisms of the topochemical reaction were proposed based on the experimental results and literatures. During the topochemical reaction process, it was noted that the conversion of kerogen to bitumen began at approximately 270°C. Three distinct reactions were identified in the kerogen–bitumen-oil/gas process, namely, low-temperature, moderate-temperature, and high-temperature oxidation. Shale gas and liquid were predominantly produced in the range of 400–500°C. In this topochemical reaction strategy, oil shale was partially oxidized to carbon dioxide and water in the presence of small quantities of air, and thus a large amount of heat was produced for further self-pyrolysis. The topochemical reaction of oil shale is a chemical heat-enhanced process that not only conserves energy but also decomposes the oil shale more thoroughly.