Pyrolysis and hydropyrolysis of two carbonaceous Australian oil shales in supercritical toluene and tetralin

Abstract

Two carbonaceous Australian oil shales from the Yaamba and Nagoorin deposits have been pyrolysed in a batch micro-autoclave tubing bomb reactor at a heating rate of ≈ 1000 K min −1. The shale samples were pyrolysed under reactive (hydrogen) and non-reactive (helium) gases, and in the presence and absence of an added reactive or non-reactive fluid phase consisting of either tetralin or toluene. Limited screening of the effect of impregnated molybdenum and platinum catalysts has also been carried out. Experiments were conducted at 450 °C and ≈ 15.2 MPa, at which conditions the added liquids were present in the reactor as supercritical fluids. Data on organic carbon conversion to oil plus gas have been obtained for residence times ranging from 2 to 30 min. Application of rapid heating under helium coupled with the presence of a non-reactive supercritical fluid phase (toluene) enhances carbon conversion to oil plus gas relative to rapid pyrolysis in the absence of supercritical toluene. Hydrogen gas in the presence of supercritical toluene is effective in increasing yields even further for the more aromatic shale, while the effect of hydrogen partial pressure is minimal for the aliphatic shale. Use of a hydrogen transfer agent as the supercritical fluid greatly enhances organic carbon conversion with yields of over 1100% of Fischer Assay achieved for the aromatic (Yaamba) oil shale. Application of impregnated molybdenum and platinum catalysts also enhances carbon conversion and oil yield, but only at elevated hydrogen partial pressures.