CO₂ Hydrogenation to Light Olefins Over In₂O₃/SAPO-34 and Fe-Co/K-Al₂O₃ Composite Catalyst

Direct CO₂ conversion to light olefins offers a chance to reduce CO₂ emission with generating the revenue. However, a lack of efficient catalysts is a barrier for promoting this technology to an industrial scale. Here, we report a new catalytic system using a composite catalyst containing In₂O₃/SAPO-34 and Fe-Co/K-Al₂O₃ to enhance the light olefins yield. The effect of catalysts bed configuration including a physical mixture of In₂O₃/SAPO-34 with Fe-Co/K-Al₂O₃ (M-InS/Fe-Co), a dual-layer packing of In₂O₃/SAPO-34 followed by Fe-Co/K-Al₂O₃ (T-InS/B-FeCo) and a dual-layer packing of Fe-Co/K-Al₂O₃ above In₂O₃/SAPO-34 (T-FeCo/B-InS) is investigated. The M-InS/Fe-Co and T-FeCo/B-InS catalysts show a light olefins yield of 11.5 and 16.2% which are lower than that (18.9%) of the single Fe-Co/K-Al₂O₃ catalyst. A drastic reduction in the BET surface area (42 m² g⁻¹) of M-InS/Fe-Co catalyst compared to its theoretical value of 198 m² g⁻¹ is observed, suggesting the pores blockage. The T-InS/B-FeCo composite catalyst achieves a state-of the art light olefins yield of 21.5% due to a selective CO₂ conversion to light olefins over In₂O₃/SAPO-34 and a highly active CO₂ conversion to hydrocarbon over Fe-Co/K-Al₂O₃ which further converts the remaining CO₂ from the former catalyst bed to light olefins and other hydrocarbon products until equilibrium CO₂ conversion is reached.