Investigation of oil-shale pyrolysis processing conditions using thermogravimetric analysis

Four oil-shale samples from two regions of Pakistan have been pyrolysed in a thermogravimetric analyser (TG-A) in relation to heating rate and tempera ture using non-isothermal and isothermal analysis respectively. The heating rates investigated in the TCA were 5-40 K min(-1) to a final temperature o f 950 degrees C. The main region of weight loss corresponding to hydrocarbo n oil and gas release was between 200 and 620 degrees C,;ind at higher temp eratures, significant weight loss was attributed to carbonate decomposition . It was found that for the oil-shale samples analysed in the TGA, increasi ng the heating rate shifted the reaction to higher temperatures. The final temperature of the pyrolysis was investigated using the isothermal TGA. The temperature range studied was from 350 to 485 degrees C. The data were ana lysed to determine the kinetic parameters of activation energy and frequenc y factor using two methods, the Arrhenius and Coats-Redfern analyses. The o rder of reaction was determined as unity. There was no clear relationship b etween activation energy and heating rate. The Coats-Redfern method of anal ysis gave consistently lower values of activation energy compared with the Arrhenius method. Isothermal analysis gave similar results to those obtaine d using the non-isothermal analysis. (C) 2000 Elsevier Science Ltd. All rig hts reserved.