Assessment of thermogravimetric methods for calculating coke combustion-regeneration kinetics of deactivated catalyst

This work compares different methodologies for calculating the kinetic parameters of coke combustion, employed for catalyst regeneration, using thermogravimetric methods. A reference fluid catalytic cracking (FCC) spent catalyst was used as a representative example of the deactivated catalyst for the combustion runs, pre-used in the cracking of a vacuum gas oil at 773 K and 3 s. Three different types of approaches have been performed in order to obtain kinetic combustion parameters: (i) kinetic model-based, (ii) isoconversional and (iii) modulated methods. Additionally, a series of empirical modifications have been proposed to predict the kinetic behavior at different heating rates for the model-based approach. Using the best conditions and methods, the combustion activation energy of coke, deposited after the reaction mentioned, is in the order of ∼114, ∼156, and ∼162 kJ mol⁻¹ for the kinetic model-based, isoconversional and modulated methods, respectively. The recommendations for measuring kinetic parameters are reported together with the benefits/disadvantages using the three mentioned approaches.