There is significant interest in developing direct natural gas upgrading routes as alternatives to current energy-intensive multi-step industrial methods of upgrading natural gas into value-added chemicals. These direct routes can potentially be applied in the upgrading of natural gas from small-scale sources; thereby mitigating their underutilization and flaring. The oxidative coupling of methane (OCM) is a promising route for direct upgrading of methane; the major component in natural gas. In OCM, methane reacts with oxygen at high temperatures, typically in the presence of a catalyst, to produce ethane and ethylene (C
2), which are key feedstocks for the chemical industry. However, the yield of C
2 products from OCM have remained below the techno-economic target due to formation of undesired CO and CO
2, particularly in conventional packed bed reactors (PBRs). Studies have shown that by applying O
2â conducting solid oxide membrane reactors that distribute the oxygen feed, the selectivity to C
2 products can be significantly increased compared to a PBR.
1 A rational design for these membrane reactors would include an O
2- conducting OCM catalyst integrated with an O
2- conducting membrane. In this study, we identify O
2- conducting perovskite oxide materials that are active and selective for OCM.
2,3 We test these materials for OCM in dense (non-porous) solid oxide membrane reactors modified with a porous O
2- conducting layer to facilitate methane activation. From our reactor tests, we identify the most promising membrane system in terms of OCM performance and stability. We also present results from our efforts to optimize the membrane reactor performance by modifying the membrane features.
(1) Farrell, B. L.; Igenegbai, V. O.; Linic, S. ACS Catal. 2016, 6 (7), 4340â4346.
(2) Farrell, B. L.; Linic, S. Catal. Sci. Technol. 2016, 6, 4370â4376.
(3) Igenegbai, V. O.; Meyer, R. J.; Linic, S. Appl. Catal. B Environ. 2018, 230, 29â35.
