Cobalt-Molybdenum Oxides for Effective Coupling of Ethane Activation and Carbon Dioxide Reduction Catalysis
Cobalt-Molybdenum Oxides for Effective Coupling of Ethane Activation and Carbon Dioxide Reduction Catalysis
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DOI：
10.1021/acscatal.2c02525
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发表时间：
2022-09
期刊：
影响因子：
12.9
通讯作者：
Rui Yao;Jayson Pinals;Roham Dorakhan;J. Herrera;Minhua Zhang;P. Deshlahra;Y. Chin
中科院分区：
文献类型：
--
作者：
Rui Yao;Jayson Pinals;Roham Dorakhan;J. Herrera;Minhua Zhang;P. Deshlahra;Y. Chin
本文报道了在C_2H_6-CO_2催化反应中发现的具有协同催化作用的CoMoOx分子。C2 H6-CO2催化通过多个伴随的催化循环发生，所述催化循环由C2 H6活化和CO2活化的双循环以及不期望的焦炭沉积循环引发。C2 H6活化需要活性氧物质来辅助动力学相关的C-H键活化;这些氧物质是由逆水煤气变换（RWGS）反应中的CO2活化循环产生的。在RWGS反应中有效的CO2活化将在CoMoOx部分中保留更高的O含量，导致更有效的动力学相关的C-H键活化C2 H6和焦炭前体的氧化，从而增加周转率，同时减轻失活。这种机械的洞察力使我们设计了CoMoOx部分，其中Co阳离子充当刘易斯酸。与邻位氧空位一起，Co阳离子通过形成动力学相关的[Co···C（O）<$O··· □空位···Mo] n过渡态通过空位途径活化CO2，在该过渡态下Co与C相互作用，氧空位（□空位）夺取CO2的离开O。动力学耦合循环导致脱氢和重整反应中的乙烷转化率都直接取决于RWGS反应速率。速率偶联的这种机械理解导致了具有有效的C2 H6-CO2催化的双官能度的CoMoOx部分的设计。
This study reports the discovery of CoMoOxmoieties with synergistic catalytic roles in C2H6–CO2catalysis. C2H6–CO2catalysis occurs through multiple, concomitant catalytic cycles, initiated by the dual cycles of C2H6activation and CO2activation, together with an undesired coke deposition cycle. C2H6activation requires reactive oxygen species that assist with the kinetically relevant C–H bond activation; these oxygen species are generated from the CO2activation cycle within the reverse water-gas shift (RWGS) reaction. An efficient CO2activation in the RWGS reaction would retain higher O contents in CoMoOxmoieties, leading to more effective kinetically relevant C–H bond activation of C2H6and oxidation of coke precursors and thus increasing turnovers while mitigating deactivation. This mechanistic insight led us to design CoMoOxmoieties, where the Co cation acts as a Lewis acid. Together with a vicinal oxygen vacancy, the Co cation activates CO2via aVacancyroute through the formation of a kinetically relevant [Co···C(O) ═ O··· □vacancy···Mo]‡transition state, at which the Co interacts with the C and the oxygen vacancy (□vacancy) abstracts the leaving O of CO2. The kinetically coupled cycles lead the ethane conversion rates in dehydrogenation and reforming reactions to both depend directly on the RWGS reaction rates. This mechanistic understanding of rate coupling has led to the design of CoMoOxmoieties with dual functionality for effective C2H6–CO2catalysis.