关键词: 油砂, 热重分析, 气体逸出顺序, 核磁和红外分析, 热解机理

Abstract:

The pyrolysis characteristics of oil sand at different heating rate was investigated by using a thermogravimetric analyzer. The results showed that the mass loss of oil sand sample contained four processes: desorption, low temperature pyrolysis, main pyrolysis and char condensation. The evolution order of CO₂, CO, C₂H₆, CH₄ and H₂ was determined via the micro fixed bed reactor coupled with mass spectra analyzer, and the corresponding initial releasing temperature were 155, 178, 146, 174 and 354℃, respectively. The composition and chemical structure parameters of liquid and solid products in different temperature ranges were studied by NMR spectroscopy and IR spectrometry. The results showed that the principle reaction before 350℃ was desorption of light oil, in which the aromatic carbon ratio amounted to 7.92% including the breaking of carboxylic and alkyl side chains. The oil sand pyrolysis process mainly occurred in the temperature range of 350—520℃. The aromatic carbon ratio of the obtained pyrolysis oil was 23.51%. By using Coats-Redfern method, the corresponding activation energy of low temperature pyrolysis and main pyrolysis process were 27.63 and 90.30 kJ·mol^-1, respectively, indicating that the activation energy of ring-opening and cracking reaction was higher than that of desorption of oil sand, decomposition of carboxyl and breaking of the weak bonds.

Key words: oil sand, pyrolysis, gas evolution order, NMR and IR analysis, pyrolysis mechanism