This study compares the catalytic activity of CO oxidation over two perovskite catalysts: stoichiometric LaCoO and non-stoichiometric LaCoO. Through catalytic activity and kinetic analysis, we aim to propose a strategy for designing efficient non-stoichiometric perovskite catalysts. The non-stoichiometric LaCoO catalyst exhibits superior activity in CO oxidation compared to the stoichiometric LaCoO catalyst. X-ray photoelectron spectroscopy (XPS) and Oxygen-temperature programmed desorption (O-TPD) results reveal an enrichment of adsorbed oxygen species, which are crucial for CO oxidation reactions, on the surface of non-stoichiometric LaCoO. This suggests that non-stoichiometric composition effectively generates oxygen vacancies on the catalyst surface, facilitating the formation of adsorbed oxygen species. Interestingly, a higher apparent activation energy is observed for the LaCoO compared to the LaCoO, while the reaction orders of CO are 1.0 and − 1.5 for the LaCoO and the LaCoO, respectively. Based on these findings, we conclude that the LaCoO follows the Mars-van Krevelen mechanism, utilizing lattice oxygen at high temperatures, while the LaCoO operates via the Langmuir-Hinshelwood mechanism at lower temperatures due to its enriched adsorbed oxygen species. This underscores non-stoichiometry as an efficient catalyst design strategy for enhancing catalytic activity of perovskites in various oxidation reactions where adsorbed oxygen species play a crucial role.

中文翻译：

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用于 CO 氧化的化学计量 (LaCoO3) 与非化学计量 (LaCo0.9O3−δ) 钙钛矿催化剂：动力学和反应模型

本研究比较了两种钙钛矿催化剂（化学计量的 LaCoO 和非化学计量的 LaCoO）的 CO 氧化催化活性。通过催化活性和动力学分析，我们旨在提出一种设计高效非化学计量钙钛矿催化剂的策略。与化学计量的LaCoO催化剂相比，非化学计量的LaCoO催化剂在CO氧化中表现出优异的活性。 X 射线光电子能谱 (XPS) 和氧温度程序解吸 (O-TPD) 结果表明，非化学计量 LaCoO 表面吸附的氧物质富集，这对于 CO 氧化反应至关重要。这表明非化学计量组成有效地在催化剂表面产生氧空位，促进吸附氧物质的形成。有趣的是，与 LaCoO 相比，LaCoO 具有更高的表观活化能，而 LaCoO 和 LaCoO 的 CO 反应级数分别为 1.0 和 − 1.5。基于这些发现，我们得出结论，LaCoO遵循Mars-van Krevelen机制，在高温下利用晶格氧，而LaCoO由于其丰富的吸附氧物种，在较低温度下通过Langmuir-Hinshelwood机制运行。这强调了非化学计量作为一种有效的催化剂设计策略，可增强钙钛矿在各种氧化反应中的催化活性，其中吸附的氧物种起着至关重要的作用。