Abstract
Alkanolysis has become an effective approach for lignite extraction due to high organic oxygen content in lignite. To better understand the effect of isopropanolysis on the chemical structure and thermal degradation process of lignite, Wucaiwan lignite (WL) and isopropanolyed residue (RI) were systematically analyzed using four multiple direct tools, including Fourier transform infrared spectrometer (FTIRS), X-ray photoelectron spectrometer (XRPES), Thermogravimetric analysis (TGA), and Pyrolysis-gas chromatography/mass spectrometry (PGC/MS). Combining with the analysis of FTIRS and XRPES, much oxygen-containing species were extracted from WL during isopropanolysis process (IP), and RI has higher carbon content than WL. Kinetic parameters such as activation energy (Ea) and pre-exponential factor (A) were determined by using two model-free methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). Average Ea for WL pyrolysis was 235.4 and 235.7 kJ mol−1, respectively, obtained by KAS and FWO methods, were lower than that of RI (354.4 and 351.3 kJ mol−1). Besides, based on the obtained kinetics data, thermodynamic analysis was established to evaluate the pyrolysis complexity of WL and RI. PGC/MS results showed that the main volatile products (VPs) of RI fast pyrolysis (FP) were arenes and alkanes while formation of oxygenated compounds reduced, further confirming the extraction of oxygen-containing species from IP of WL. It is noteworthy that isopropanolysis pretreatment of WL can influence its chemical structure and thermal degradation process.
Published Version
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