CO2 hydrogenation to olefins on supported iron catalysts: Effects of support properties on carbon-containing species and product distribution

Catalytic utilizing of CO 2 into valuable olefins on Fe-based catalysts is a feasible way to mitigate the pressure of carbon neutrality. Herein, by investigating the effects of support (SiO 2 , Al 2 O 3 , CNT, and ZrO 2 ) on the structure and catalytic performance of iron catalysts, we have found that ZrO 2 supported catalysts are more beneficial to olefin selectivity and chain growth. The optimization catalytic performance of FeNa/ZrO 2 displays C 2 -C 7 olefin selectivity of 68.2% (O/P = 8.0) with a space time yields (111.4 g Kg cat -1 h −1 ) at X CO2  = 32.7%, 320 ⁰C, 2.0 MPa, CO 2 /H 2 /Ar = 1:3:3, and 9000 mL g -1 h −1 . Characterizations show that the support regulates the composition of the iron oxide phase and the iron carbide phase and induces to form the highest content of Fe 5 C 2 on the spent FeNa/ZrO 2 , which is probably caused by the carbon rich surface and lower disorder of carbon species. Besides, the higher intensity of CO 2 and CO adsorption and lower intensity of H 2 adsorption is confirmed on the surface of the FeNa/ZrO 2 catalysts, leading to a higher ratio of C/H on the surface of the spent catalysts and consequently inhibiting the hydrogenation of olefins. Therefore, the O/P is 8 times as many as that on the FeNa/SiO 2 and FeNa/Al 2 O 3 . Understanding the effect of support on CO 2 hydrogenation to olefins over iron-based catalysts would be significant for precisely designing new catalysts.