Effect of beeswax and petroleum wax on the thermal degradation behavior, kinetics, and thermodynamics of low-grade coal

The co-pyrolysis behavior of low-grade coal with two different feedstocks (beeswax and petroleum wax) at different compositions (w/w) [(75:25), (50:50), (25:75)] is investigated by using a thermogravimetric (TG) analyzer under the non-isothermal condition at a constant heating rate of 20(degrees)C/min from an ambient temperature to 900 degrees C under nitrogen atmosphere. The kinetic and thermodynamic analysis for the thermal decomposition of the sample parameters was carried out by applying the model fitting Coats-Redfern method to the thermogravimetry data of different feedstocks. The activation energy of thermal degradation of coal is found to be 55.8 kJ/mole. A decrease in activation energy is observed by the addition of 25% and 50% waxes in the blended sample and the blended sample with 25% wax and 75% coal has the lowest activation energy. The activation energy for coal-beeswax blend (75:25) is 35.718 KJ/mol, but it is 34.237 KJ/mol for coal-petroleum wax blend (75:25). The value of increment H decreases by the addition of waxes and follows the order (Coal: Feedstock) {(75:25) < (50:50) < (25:75)}, while that of value of increment S increases by the addition of waxes and follows the order {(75:25) > (50:50) > (25:75)}. However, the value of Delta G does not significantly shift as the blend ratio of the feedstocks is altered. The addition of both feedstocks with the coal sample showed some degree of synergy. The result illustrates that the co-pyrolysis of coal with wax be energy economical than individual pyrolysis and this study would give precious scope to design a more efficient conversion system.