Product evolution during rapid pyrolysis of Green River Formation oil shale

Abstract

The devolatilization of rich (209 cm 3 kg −1), rapidly heated (1000 K s −1) Green River Formation, Colorado, oil shale has been studied at temperatures from ≈ 600 to 1100K, under helium (170 kPa) and vacuum. Oil yields decrease with increasing pressure at temperatures above the 800–900 K range. This is attributed to an increased probability of condensed phase cracking reactions involving oil precursors with increased pressure. The fact that escape of the oil from shale particles is vaporization-rate limited is supported by a comparison of the molecular weights of oil collected outside the particle and that left within the particle. The measured nature of particle porosity is consistent with the view that external gas pressure can affect vaporization rates within pores. Elemental and infrared characterization of different molecular weight fractions of oil are presented.