Thermochimica Acta, 125 (1988) 285-294 Elsevier Science Publishers B.V.. Amsterdam - Printed in The Netherlands 285 EFFECT OF CALCIUM CHLORIDE AND CALCIUM ACETATE ON THE REACTIVITY OF A LIGNITE COAL AT LOW HEATING RATE WEI-PING PAN Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101 (U.S.A.) M.A. SERAGELDIN Department of Chemistry and Chemical Engineering, Michigan Technological University, Houghton, MI 49931 (U.S.A.) (Received 8 June 1987) ABSTRACT The effect of calcium chloride and calcium acetate on the rate of decomposition of a lignite coal and its char was investigated under both pyrolysis and combustion conditions. The experiments were undertaken in a thermogravimetric analyzer under low (20 o C mini’) and intermediate (2100’ C mm-‘) heating rates. Both calcium chloride and calcium acetate slightly reduced the amount of coal decom- posed at 10’ N mm2 m a nitrogen atmosphere. However, the inhibiting effect of calcium acetate was dependent on the sample size and packing density. In the presence of oxygen, addition of calcium chloride to coal produced two opposite effects: at low temperatures an inhibiting effect due to the chloride and at higher temperatures a promoting effect due to the catalytic role of the calcium. Lastly, the additives reduced the apparent activation energy and increased the heat reaction of the lignite coal. NOMENCLATURE A E C” k m zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA mi 2l,& n zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA R R max T pre-exponential factor in the Arrhenius equation activation energy (kJ mol-i) a weighted overall E based on eqn. (2) (kJ mol- ’ ) rate constant in the Arrhenius equation (min-‘) mass at T (mg) initial mass (mg) final mass (mg) rate of mass loss (mg min-‘) order of reaction taken as unity the gas law constant (8.314 J mol-’ K-‘) maximum reactivity (min-‘) absolute temperature (K) 0040-6031/88/$03.50 0 1988 Elsevier Science Publishers B.V.