This study is to convert renewable H(2 )and increasingly concerned CO2 to ethylene or C2H4 over Fe3.33Co1.67K5/ZrO2 and Fe3.33Co1.67K5/Al2O3 catalysts. The ZrO2 support provides amounts of surface oxygen vacancies (OVs) as well as stable and rich surface hydroxyl groups (-OH), which promotes the Fe3.33Co1.67K5/ZrO2 catalysts with 5% Fe and Co loadings to achieve C2H4 space time yield (STY) of 0.064 mmol(C2H4.)m(-2) cat . h(-1 )at 290 degrees C and 2.0 MPa, while the Fe3.33Co1.67K5/Al2O3 catalysts only reach C2H4 STY of 0.009 mmol(C2H4) . m(-2) cat . h(-1) at 330 degrees C and 2 MPa Fe3.33Co1.67K5/ZrO2 catalysts are very promising for converting the captured CO2 and renewable H-2 to highly demanded C2H4. This work not only provides a guideline for developing efficient catalysts but also advances the mechanistic understanding of catalytic CO2 hydrogenation. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.