Evolution of Light Hydrocarbons from a Coked Ferrierite Catalyst during Temperature-Programmed Gasification

The evolution of light hydrocarbons during temperature-programmed gasification with helium (TPHe) of a coked ferrierite catalyst was studied to gain information on partial coke removal by heat treatment under inert flow. The catalyst had been deactivated in the skeletal isomerization of alkenes. Characterization by DRIFTS, GC−MS, and 13C CPMAS NMR revealed that the coke contained two- and three-ring aromatic hydrocarbons, as well as polyaromatics. Evolution predominantly of C2−C5 hydrocarbons was observed during TPHe between 200 and 500 °C. The main components were propene and ethene. The carbon content of the catalyst dropped from 4.3 to 3.5 wt % during TPHe. Kinetic models suitable for the purpose of designing a coke removal unit were derived for the evolution of carbon fractions between C2 and C5 from the ferrierite zeolite. The results of the kinetic modeling suggest that one or several bimolecular reactions are relevant in the formation of light hydrocarbons from coke.