Effect of sensitive group-fractions on the generation of volatile products during fast thermal upgrading of Buton oil sand bitumen

In order to in-depth investigate the influence of sensitive group-fractions affecting the formation of volatile products on the efficient thermal conversion of Buton oil sand bitumen (OSB), the average structural parameters of aromatics (Ar), resins (Re) and their sub-fractions as sensitive group-fractions were analyzed at the near-molecular level firstly. Subsequently, the thermal-cracking characteristics of these sensitive fractions and the determination of the specific sensitive group-fraction that affected most significantly on the volatiles generation during thermal upgrading process of Buton OSB were investigated via TG–FTIR. The results indicated that thermal-cracking behaviors of Ar, Re and their sub-fractions were disparate on the grounds of their thermal-cracking characteristic parameters and the release laws of detected gaseous products. A novel analysis method was proposed to determine the most sensitive group-fraction based on the variation and its rangeability of thermal mass loss rate of these group-fractions at various heating rate and temperature. The sensitive group-fraction was inclined to be heavier with the incremental temperature at the same heating rate. Finally, the formation behaviors of the thermal-cracking volatile products of sensitive group-fractions were explored by Py–GC/TOF–MS. It was found that the relative content and carbon number distribution of various classes of volatile products (i.e., alkenes, alkanes, diolefins and aromatics) for sensitive group-fractions showed the different changing trends due to the diversity of composition and structure of sensitive group-fractions influencing the reaction pathway. As the sensitive group-fractions tended to be heavier from L-Ar to H-Re, the sensitive group-fraction had more significant contribution to the formation of alkanes and aromatics in volatile products of OSB yet the lessened influence on the generation of alkenes products.