Mass loss evolution of bituminous fractions at different heating rates and constituent conformation of emitted volatiles

Abstract

Bitumen is frequently used as energy source. To further understand bituminous combustion and emitted volatiles during its energy generation and conversion at the fraction level including saturates, aromatics, resins, and asphaltenes (SARA), an elemental analyzer, thermogravimetry coupled with mass spectrometer and Fourier‐transform infrared spectroscopy (TG‐MS‐FTIR) were utilized to monitor the mass loss evolution, and confirm molecular structures of emitted volatiles, and track the whereabouts of main elements during each SARA fraction combustion. Results indicate that TG, DTG, and Gram‐Schmidt (G‐S) curves show two‐stage characteristics, while the total ion chromatogram (TIC) curves present one‐stage characteristic during each SARA fraction combustion. Also, as the heating rate is raised, TG, DTG, TIC, and G‐S curves are shifted to higher temperature and the total emitted volatile amount is increased from saturates to asphaltenes. Molecular weights of main volatiles are distributed in the range of 12‐64. The elemental species of volatiles are consistent with those of SARA fractions. Finally, the typical volatiles of saturates and aromatics are similar, and the release amount of CO and CO2 at stage II is larger than those at stage I. SO2 is released during the combustion of resins. SO2 and NO2 are identified in volatiles of asphaltenes.

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