Oil shale pyrolysis kinetics and variable activation energy principle

A modified first order kinetic equation with variable activation energy is employed to model the total weight loss of Ellajun oil shale samples. Fixed bed retort with 400 g of oil shale sample size is used in this study in 350-550 degrees C temperature range. Variable heating rate, h, in the range 2.6-5 degrees C min(-1) are tested. Activation energy was allowed to vary as a function of oil shale conversion. The value of the activation energy increased from 98 to 120 kJ mol(-1) while the corresponding frequency factor changed from 9.51 x 10(5) to 1.16 x 10(6). Fischer Assay analysis of the studied samples indicated 12.2 wt.% oil content. The oil shale decomposition ranged from 3.2% to 28.0%. The obtained kinetic data are modeled using variable heating rate, pyrolysis temperature and variable activation energy principle in a nitrogen sweeping medium. Good fit to the obtained experimental data is achieved. (C) 2009 Elsevier Ltd. All rights reserved.