Coke formation through the reaction of olefins over hydrogen mordenite: I. EPR measurements under static conditions

Abstract

Depending on the reaction temperature, the carbonization of ethylene and propylene over hydrogen mordenite can be separated into two processes. Below 500 K, radicals of a low-temperature coke develop and are subsequently annihilated. Above 500 K, highly unsaturated radicals of high-temperature coke form. The presence of reactive species in the gas phase, which approximates the on-stream situation, may affect the carbonization of the low-temperature coke. However, radicals of the low-temperature coke do not appear to be necessary precursors of the high-temperature coke. Paramagnetic centers which are detectable after dehydration of the zeolite do not interact with the adsorbed olefins to form radicals.