Electrochemical conversion of methane to ethylene in a solid oxide electrolyzer

Changli Zhu,Jinhai Lu,Xiuli Hu,Shisheng Hou,Kui Xie,Fanglin Chen

doi:10.1038/s41467-019-09083-3

Abstract

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts. Here we demonstrate a conceptually different process of in situ electrochemical oxidation of methane to ethylene in a solid oxide electrolyzer under ambient pressure at 850 °C. The porous electrode scaffold with an in situ-grown metal/oxide interface enhances coking resistance and catalyst stability at high temperatures. The highest C2 product selectivity of 81.2% together with the highest C2 product concentration of 16.7% in output gas (12.1% ethylene and 4.6% ethane) is achieved while the methane conversion reaches as high as 41% in the initial pass. This strategy provides an optimal performance with no obvious degradation being observed after 100 h of high temperature operation and 10 redox cycles, suggesting a reliable electrochemical process for conversion of methane into valuable chemicals.

Highlights

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts
Mainly C2H4, as key chemical feedstocks and building blocks, are currently produced through multistage processes from syngas to methanol and to olefins, there is some ongoing research of direct conversion of syngas to olefins
The iron in the host lattice is mainly present in the form of Fe3+/4+ oxidation state as shown in the X-ray photoelectron spectroscopy (XPS) in Supplementary Fig. 1

Summary

Introduction

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts. Mainly C2H4, as key chemical feedstocks and building blocks, are currently produced through multistage processes from syngas to methanol and to olefins, there is some ongoing research of direct conversion of syngas to olefins This syngas-to-olefin route is dominant in current and near-term industry production[2,3,4,5]; the carbon-atom efficiency is normally below 50% in addition to the significant amount of CO2 emission. CH4 is a small and stable molecule that exists in nature, and it has strong C–H bonds, negligible electron affinity, large ionization energy, and low polarizability This direct-conversion route can be realized through either oxidative coupling or direct nonoxidative conversion in a heterogeneous catalysis process[1].

Methods

Results

Conclusion