Kinetic Analysis of Devolatilized Diesel-Soot Oxidation Catalyzed by Ag/Al2O3 and Ag/CeO2 Using Isoconversional and Master-Plots Techniques

This work presentedthe kinetic analysis of devolatilized diesel-sootcombustion accelerated by Ag/Al2O3 and Ag/CeO2 catalysts. Isoconversional and master-plots techniques wereemployed to estimate activation energy and identify the reaction model.The apparent activation energy of uncatalyzed soot oxidation was 101.85kJ/mol, and it was reduced to 61.85 and 82.78 kJ/mol for the combustioncatalyzed by Ag/Al2O3 and Ag/CeO2, respectively. The reaction-order model, f(& alpha;)= (1- & alpha;)n, with n of1.4, 1, and 1 showed the best fit for the uncatalyzed soot oxidationand soot oxidation catalyzed by Ag/Al2O3 andAg/CeO2, respectively. The proposed single-step reactionmodels were quite capable of reproducing experiments for the uncatalyzedsoot oxidation and soot oxidation catalyzed by Ag/CeO2.In the presence of Ag/Al2O3, the oxidation rateat the first 20% of conversion was faster than the 1st-order reactionreflecting that the soot was rapidly oxidized by highly active speciesgenerated by Ag/Al2O3. The oxidation of theremaining soot closely followed the 1st-order reaction mechanism.