Highly Efficient CO₂ Hydrogenation to Linear α-Olefins on FeZnK Catalysts with Balanced Zn–O–Fe Interfaces and Fe₅C₂ Species

This is the authors' abstract. We don't add key points for this paper.

C 4+ linear α-olefins (LAOs) synthesis from direct CO 2 hydrogenation is a promising strategy to realize the fixation of CO 2 to high-value chemical products. However, identifying active catalysts with satisfactory activity and selectivity is quite difficult nowadays. Herein, we fabricate a series of iron–zinc–potassium (FeZnK) catalysts via a citric acid-mediated combustion method that can both actively and selectively synthesize LAOs from CO 2 hydrogenation. The Fe 1 Zn 0.1 K 0.1 catalyst with balanced Zn–O–Fe interfaces and active Fe 5 C 2 species provides an LAOs selectivity of 44.7% at a high CO 2 conversion of 43.3% in CO 2 hydrogenation. Notably, the space–time yield of LAOs over Fe 1 Zn 0.1 K 0.1 reaches 0.40 g·g cat –1 ·h –1, surpassing the performance of current state-of-the-art Fe-based catalysts. The reaction results and multiple characterizations reveal that the introduction of an appropriate amount of Zn composition can not only enhance the CO 2 adsorption ability by forming Zn–O–Fe interfaces but also improve the LAOs selectivity by promoting the formation of active Fe 5 C 2 species. Interestingly, active Fe 5 C 2 species tend to form in the bulk phase of the FeZnK catalysts, which are more closely correlated with catalytic activity. In situ / ex situ characterizations combined with H 2 /D 2 exchange and CO pulse hydrogenation probe experiments elucidate the structure–activity relationship and reaction mechanism. Furthermore, Fe 1 Zn 0.1 K 0.1 shows a 160 h long-time on-stream stability, indicating its strong potential as an industrial catalyst for direct CO 2 conversion to high-value LAOs.