Light olefins, traditionally sourced from petroleum, are currently being investigated through alternative routes, such as CO2 hydrogenation, aligning with CCUS policies. Alkali-promoted Fe-based catalysts have shown promise in coupling reverse water–gas shift and Fischer-Tropsch processes to produce light olefins from CO2 directly. The in-situ generated Fe5C2 phase is commonly associated with the high activity of these catalysts. However, the preparation methods employed can lead to distinct catalyst properties, which considerably impact the performance during the reaction. Here, we investigate different strategies to introduce K and Fe in the KFeCeZr system and correlate catalyst properties with catalytic activity during CO2 hydrogenation at ambient pressure. The catalyst prepared by one-pot precipitation of Fe, Ce, and Zr followed by K impregnation showed the most promising results in terms of conversion and productivity of light olefins. The effective incorporation of Fe in the CeZrOx structure during synthesis was essential for maintaining the high dispersion of metallic Fe particles after reduction, improving reactant chemisorption. Under reaction conditions, this catalyst showed the most remarkable propensity to form iron carbides (FexCy), mainly composed of Fe5C2 phase. In general, this work highlights the impact that the construction steps of a multifunctional catalyst have on the physicochemical properties and, consequently, on the catalytic activity.

中文翻译：

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KFeCeZr 催化剂中 K 和 Fe 插入法对室压下 CO2 加氢制 C2/C3 烯烃的影响


传统上来自石油的轻烯烃目前正在通过替代途径进行研究，例如 CO2 加氢，这与 CCUS 政策保持一致。碱促进铁基催化剂在耦合逆水-气变换和费托工艺以直接从 CO2 生产轻质烯烃方面显示出前景。原位生成的 Fe5C2 固定相通常与这些催化剂的高活性有关。然而，所采用的制备方法会导致不同的催化剂性质，这会大大影响反应过程中的性能。在这里，我们研究了在 KFeCeZr 系统中引入 K 和 Fe 的不同策略，并将催化剂特性与环境压力下 CO2 加氢过程中的催化活性相关联。Fe、Ce和Zr一锅沉淀后K浸渍制备的催化剂在轻烯烃的转化率和生产率方面显示出最有希望的结果。Fe 在合成过程中有效掺入 CeZrOx 结构中对于维持金属 Fe 颗粒在还原后的高分散性、改善反应物化学吸附至关重要。在反应条件下，该催化剂表现出最显著的形成碳化铁 （FexCy） 的倾向，主要由 Fe5C2 相组成。总的来说，这项工作强调了多功能催化剂的构建步骤对物理化学性质的影响，从而对催化活性的影响。