CO2 辅助乙烷脱氢过程中 Co 形态的演化：C-H 和 C-C 键的竞争断裂,ACS Catalysis

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CO2 辅助乙烷脱氢过程中 Co 形态的演化：C-H 和 C-C 键的竞争断裂
ACS Catalysis ( IF 11.3 ) Pub Date : 2024-03-13 , DOI: 10.1021/acscatal.4c00324
Yingbin Zheng _{1,

2} , Junjie Li ₁ , Xinbao Zhang ₁ , Shaoguo Li ₁ , Jie An ₁ , Fucun Chen ₁ , Xiujie Li ₁ , Xiangxue Zhu ₁

Affiliation

将CO ₂整合到烷烃脱氢反应中为提高金属催化剂的稳定性提供了有效的策略。负载金属物质的结构演变，特别是在轻度氧化气氛中，对催化性能起着重要作用。在此，详细研究了CO ₂的引入对Co物种状态的影响以及Co/Silicalite-1相应的脱氢性能。 CO ₂ /C ₂ H ₆进料比的控制决定了乙烷中 C-H 或 C-C 的选择性键断裂，这是通过一系列设计的控制反应在反应过程中 Co 物种的差异化纳米结构衍生的测试和表征结果。当CO ₂ /C ₂ H ₆进料比为4.0时，Co纳米粒子转变为活性金属Co物种，这有利于干重整反应，乙烯选择性低于2%。当CO ₂ /C ₂ H ₆进料比低于2.0时，活性金属Co物种的生成受到抑制，并且脱氢反应在Co ²⁺位点上占主导地位。有效抑制活性Co ²⁺物质的还原和烧结导致脱氢性能稳定持续超过120小时，在此期间乙烯选择性始终超过95%。 Co物种状态变化的阐明对于脱氢催化剂的设计具有重要意义。

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Evolution of Co Species in CO2-Assisted Ethane Dehydrogenation: Competing Cleavage of C–H and C–C Bonds

Integrating CO₂ into alkane dehydrogenation reactions provides an effective strategy to improve the metal catalyst stability. The structural evolution of supported metal species, particularly in a mild oxidation atmosphere, plays an important role in catalytic performance. Here, the influence of the introduction of CO₂ on the state of Co species and the corresponding dehydrogenation performance over Co/Silicalite-1 was investigated in detail. The manipulation of the CO₂/C₂H₆ feeding ratios dictated the selective bond breakage of either C–H or C–C in ethane, which was derived from the differentiated nanostructuring of Co species during reactions through a series of designed control-reaction tests and characterization results. At a CO₂/C₂H₆ feeding ratio of 4.0, Co nanoparticles underwent a transformation into active metallic Co species, which facilitated dry-reforming reaction with an ethene selectivity below 2%. When the CO₂/C₂H₆ feeding ratio was below 2.0, the generation of active metallic Co species was suppressed and the dehydrogenation reaction dominated over the Co²⁺ sites. The effective suppression of reduction and sintering of active Co²⁺ species led to a stable dehydrogenation performance lasting over 120 h, with ethene selectivity consistently exceeding 95% during this period. The elucidation of the state changes of Co species holds significant implications for the design of dehydrogenation catalysts.

更新日期：2024-03-13

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