Structure of Wangqing oil shale and mechanism of carbon monoxide release during its pyrolysis

In this work, the structural characteristics of Wangqing oil shale were investigated using C-13 nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FTIR) techniques. The thermogravimetric-Fourier-transform infrared spectroscopy (TG-FTIR) was used to pyrolyze samples and study their kinetics at four different heating rates. Meanwhile, the peak fitting method was used to study the carbon monoxide (CO) produced during the pyrolysis process. The results indicated that the oil shale was mainly composed of aromatic, aliphatic, hydroxyl, and oxygen-containing functional groups, among which the aliphatic group was the most abundant. The pyrolysis process of oil shale was divided into four stages, whereas the pyrolysis weight loss and volatilization were concentrated in the second stage. When the number of peaks was 4, the fitting results were the best, which indicated that the precipitation of CO gas was affected by the four different types of reactions and was mainly the result of oxygen group and its side chain fracture.