KINETICS GOVERNING MICHIGAN ANTRIM OIL SHALE: I - PYROLYSIS, II - OXIDATION OF CARBONACEOUS RESIDUE

The intrinsic reaction rate kinetics for the pyrolysis of Michigan Antrim oil shale and the oxidation of the carbonaceous residue of this shale have been determined. The effect of heating rate, and oil shale minerals, particularly iron pyrite on the pyrolysis reaction have also been investigated. As a part of the combustion process, the oxidation reactivity of carbonaceous residue prepared at several final pyrolysis temperatures, and the kinetics of chemisorption of oxygen on carbonaceous residue have been determined. Thermogravimetric and differential thermogravimetric techniques were employed in this research.;No evidence of any reaction among the oil shale mineral constituents was observed at temperatures below 1173(DEGREES)K. However, it was found that the presence of pyrite in oil shale reduces the primary devolatization rates of kerogen and increases the amount of residual char in the spent shale.;Carbonaceous residues which were prepared by heating the oil shale at a rate of 0.166(DEGREES)K/s to temperatures between 923(DEGREES)K and 1073(DEGREES)K, had the highest reactivities when oxidized at 0.166(DEGREES)K/s in a gas having 21 volume percent oxygen.;Oxygen chemisorption was found to be the initial precursor to the oxidation process. The kinetics governing oxygen chemisorption is.;The kinetics of the pyrolysis reaction were determined from both isothermal and nonisothermal rate data. The reaction was found to be second-order with an activation energy of 252.2kJ/mole, and with a frequency factor of 9.25 x 10('15) sec('-1). Pyrolysis kinetics were not affected by heating rates between 0.01(DEGREES)K/s to 0.67(DEGREES)K/s.;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI).;where X is the fractional coverage.;The oxidation of the carbonaceous residue was found also to be second-order. The activation energy and the frequency factor determined from isothermal experiments were 147 kJ/mole and 9.18 x 10('7) sec('-1) respectively, while the values of these parameters obtained from nonisothermal experiment were 212 kJ/mole and 1.5 x 10('13) sec('-1). The variation in the rate constants is attributed to the fact that isothermal and nonisothermal analyses represent two different aspects of the combustion process.