Highly Efficient Conversion of Methane to Olefins via a Recycle-Plasma-Catalyst Reactor

Abstract

Spark discharge plasma is an efficient means to activate methane. In this work methane was converted to olefins via a two stage recycle-plasma-catalyst reactor. A recycle spark discharge plasma reactor was employed in the first stage to actively convert methane to a mixture comprising mainly acetylene and hydrogen. The mass transfer in the pulsed spark discharge channel was strengthened by recycling part of plasma effluent to the entrance, which improved the reactivity and energy efficiency of the plasma reactor. Pd and Ni based MgAl₂O₄ supported catalysts were employed in the second stage to selectively hydrogenate acetylene in the plasma reactor effluent. With the conversion of methane of 73 % the integration of recycle plasma and catalyst reactor may obtain a ethylene yield of 55 and 35 % on 0.3 wt% Pd-0.6 wt% Ag/MgAl₂O₄ and 2.5 wt% Ni-7.5 wt%-Zn/MgAl₂O₄ catalysts, respectively. Other than ethylene about 23 % of methane was transformed to C₃–C₅ light olefins over cheap 2.5 wt% Ni-7.5 wt% Zn/MgAl₂O₄ catalysts.

Graphical Abstract