A Study on Pyrolysis Characteristics and Product Release Mechanisms of Oil Shale

Abstract

Abstract To investigate the effects of reaction atmosphere on the oxidative thermal conversion and product-evolution characteristics of oil shale, Maoming oil shale and its extracted kerogen were examined by thermogravimetric analysis (TG) and simultaneous thermal analysis coupled with Fourier-transform infrared spectroscopy and mass spectrometry (STA-FTIR-MS) under air and nitrogen. The oil-shale mass-loss process was divided into three characteristic stages. In the present experiments, the onset of the principal mass-loss region under air occurred approximately 50 °C earlier than under nitrogen, and kerogen displayed pronounced exothermic behavior in air but a mild endothermic response in nitrogen. Isoconversional OFW and DAEM analyses yielded atmosphere-dependent apparent kinetic parameters; because oxidation, oxygen uptake, volatilization, and combustion may overlap during heating in air, these parameters describe the overall mass-change process and are not interpreted as intrinsic thermal-cracking barriers directly comparable with those obtained under nitrogen. The uncalibrated MS signals and FTIR spectra show distinct atmosphere-dependent evolution profiles for H2, H2O, CH4, CO2, and light hydrocarbons. These observations identify differences in product-evolution temperature ranges and relative signal profiles but do not establish absolute product yields, a carbon balance, or a unique reaction pathway. The results support further laboratory-scale evaluation of air-assisted conversion, while field-scale feasibility requires quantitative heat-balance, oxygen-demand, heat-loss, front-stability, and energy-efficiency assessments.