Kinetic Study of the Thermal and Catalytic Cracking of Waste Motor Oil to Diesel-like Fuels

Considering the serious impact caused to the environment by the inappropriate disposal of waste motor oils, it is essential to find alternative mechanisms to handle and dispose these wastes in a controlled process. The reuse of waste motor oil as a resource for the synthesis of diesel-like fuels provides an alternative way for the disposal of this residue in a feasible, sustainable, and environmentally responsible way. This work addresses the kinetic study of the catalytic cracking of waste motor oil using mesoporous aluminum silicate materials impregnated with 1 and 2% zinc. Both the waste motor oil and liquid fuel product were characterized according to ASTM standards to ensure an adequate characterization and to guarantee the proper quality of the product. The results from the overall kinetic approach show that the cracking reaction can be described using a first-order rate equation with respect to the concentration of the used motor oil. The activation energy for the thermal cracking reaction is 370 kJ/mol. It is reduced by 22% to 287 kJ/mol when the alumina silicate catalysts are used. Also, during the reaction, the overall yield of the reaction with respect to the liquid fuel is increased from 63% during the thermal reaction to 90% during the catalytic reaction.