CO₂-mediated oxidative dehydrogenation of propane (CO₂-ODHP) has attracted great attention, as it not only efficiently favors propylene production but also provides a promising route for carbon neutralization. The present work has developed a highly efficient CO₂-ODHP catalyst Ni_2.1%Cr_3.6%O_x@S1-1.0 with exceptional C₃H₈ conversion (51.7%), C₃H₆ selectivity (91.4%), long-term stability (passing through a 36 h test), and significantly enhanced CO₂ conversion (21.9% → 52.7%). This can be closely related to the incorporation of Ni into the lattice of CrO_x, forming NiCrO_x, which facilitates the adsorption and activation of CO₂, thereby promoting the timely removal of subtracted H from C₃H₈. Additionally, the evenly dispersed NiCrO_x species encapsulated by silicalite-1 (S1) also play crucial roles in the remarkable reaction efficiency and stability of Ni_2.1%Cr_3.6%O_x@S1–1.0. The specific CO₂-ODHP mechanism was systematically investigated based on the combined experimental (in situ FTIR and in situ UV–vis) and theoretical (Density Functional Theory) simulations, which illustrates a bifunctional catalysis process that the dehydrogenation of C₃H₈ to C₃H₆ predominantly occurs over the Cr site, while CO₂ adsorption, activation, and subsequent reaction with dissociated H mainly occurs over the Ni site. The DFT-based microkinetic modeling quantitatively validates the significantly higher reaction efficiency following Ni incorporation (7.42 × 10^–7 → 6.10 × 10⁷ s^–1), which is 14 orders of magnitude higher than that of the CrO_x site. Electronic structure analyses further demonstrate that Ni incorporation efficiently reduces the band gap (2.43 → 0.95 eV) between the NiCrO_x site and CO₂, which is identified as the fundamental factor underlying the superior CO₂-ODHP activity of Ni_2.1%Cr_3.6%O_x@S1–1.0. Generally, the present work has developed an efficient bifunctional catalyst for CO₂-ODHP, which paves the way for other highly efficient catalyst designs.

中文翻译：

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NiCrOx@silicalite-1 与高级 CO2 利用在丙烷氧化脱氢中的作用：双功能催化和反应效率的见解

CO₂ 介导的丙烷氧化脱氢 （CO 2-ODHP） 引起了极大的关注，因为它不仅有效地促进了丙烯的生产，而且还为碳中和提供了一条有前途的途径。目前的工作开发了一种高效的 CO 2-ODHP 催化剂 Ni_2.1%Cr_3.6%O_x@S1-1.0，具有出色的 C₃H₈ 转化率 （51.7%）、C₃H₆ 选择性 （91.4%）、长期稳定性（通过 36 小时测试）和显着增强的 CO₂ 转化率 （21.9% → 52.7%）。这可能与 Ni 掺入 CrO_x 的晶格中，形成 NiCrO_x 密切相关，这有利于 CO₂ 的吸附和活化，从而促进从 C₃H₈ 中及时去除减去的 H。此外，硅石-1 （S1） 封装的均匀分散的 NiCrO_x 物质在 Ni_2.1%Cr_3.6%O_x@S1–1.0 的显着反应效率和稳定性中也起着至关重要的作用。基于结合实验（ 原位 FTIR 和原位 UV-vis）和理论（密度泛函理论）模拟，系统研究了特定的 CO_2-ODHP 机制，这说明了 C₃H₈ 到 C₃H₆ 的脱氢主要发生在 Cr 位点上的双功能催化过程，而 CO₂ 吸附、活化和随后与解离的 H 的反应主要发生在 Ni 位点上。 基于 DFT 的微动力学模型定量验证了 Ni 掺入后反应效率显著提高 （7.42 × ^10-7 → 6.10 × 10^{7 s-1}），比 CrO_x 位点高 14 个数量级。电子结构分析进一步表明，Ni 掺入有效降低了 NiCrO_x 位点与 CO₂ 之间的带隙（2.43 → 0.95 eV），这被认为是 Ni_2.1%Cr_3.6%O_x@S1–1.0 优异的 CO_2-ODHP 活性的基本因素。总的来说，本研究已经开发了一种用于 CO 2-ODHP 的高效双功能催化剂，这为其他高效催化剂设计铺平了道路。