Effect of ethane and ethylene on catalytic non oxidative coupling of methane

The effect of addition of ethane and ethylene (C(2)) on methane coupling at 1000 °C was investigated. A Fe/SiO(2) catalyst was used to determine the contributions of catalytic as well as C(2) initiated methane activation. The catalyst load as well as the residence times at 1000 °C downstream of the catalyst bed were varied. C(2) addition significantly increases methane conversion rates, similarly for both ethane and ethylene, although ethylene is more effective when operating with long residence times in the post-catalytic volume. Methane activation via C(2) addition proceeds dominantly in the gas-phase whereas catalytic C(2) activation is negligible. The catalyst has no effect on methane conversion when the feed contains more than 2 vol% C(2). Product selectivity distribution as well as total hydrocarbon yield at 10% conversion is not influenced by C(2) addition, but is influenced by the amount of catalyst as well as residence time in the post-catalytic volume at high temperature. It is proposed that C(2) impurities in natural gas change from a nuisance to an advantage by enhancing methane conversion and simplifying purification of the natural gas feed. A process is proposed in which ethylene is recycled back into the reactor to initiate methane coupling, leading to a process converting methane to aromatics.