56 超臨界水中における重質油の熱分解挙動の検討(重質油・バイオマス・コプロセッシング(2))

抄録

Treatment of heavy oils in supercritical water has attracted attention as an efficient method of upgrading the heavy oils. It is important to clarify the mechanism of heavy oil pyrolysis in supercritical water for making the process more efficient. In this study we examined the pyrolysis behavior of a bitumen in supercritical water using a batch type reactor and compared with the pyrolysis behavior of the bitumen in a nitrogen atmosphere. It was found that the bitumen was converted into lighter fractions mainly through decomposition of aliphatic groups in the bitumen for the both atmospheres up to 450℃. At above 420℃, the decomposition of aliphatic groups was faster in supercritical water than in a nitrogen atmosphere. Since the bitumen is composed of various constituents, it is reasnable to investigate the pyrolysis behaviors of the constituents separately. The pyrolysis behaviors of n-pentane soluble (maltene) and n-pentane insoluble (asphaltene) of the bitumen in supercritical was then examined. It was clarified that the decomposition of asphaltene rather than maltene was responsible for the change in a molecular weight distribution of the bitumen in supercritical water at 420℃ where the decomposition was faster in supercritical water.