Cooperative Catalysis of Vibrationally Excited CO2 and Alloy Catalyst Breaks the Thermodynamic Equilibrium Limitation
Cooperative Catalysis of Vibrationally Excited CO2 and Alloy Catalyst Breaks the Thermodynamic Equilibrium Limitation
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DOI：
10.1021/jacs.2c03764
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发表时间：
2022-07-21
影响因子：
15
通讯作者：
Nozaki, Tomohiro
中科院分区：
文献类型：
--
作者：
Kim, Dae-Yeong;Ham, Hyungwon;Nozaki, Tomohiro
利用非热等离子体（NTP）促进CO2加氢是克服传统热催化局限性的最有前途的方法之一。然而，ntp活化物质的表面催化反应动力学仍存在争议。在Pd2Ga/SiO2合金催化剂上研究了ntp活化的CO2加氢反应，并与热条件进行了比较。虽然热和NTP条件都显示出接近100%的CO选择性，但值得强调的是，当NTP激活时，CO2转化率不仅在热条件下提高了2倍以上，而且打破了热力学平衡限制。通过原位透射红外光谱研究了NTP活化物质和合金催化剂表面的机理，其中在NTP辐照过程中确定了催化剂表面的物质。此外，在反应条件下的原位x射线吸收精细结构分析中，NTP条件下的催化剂不仅没有发生影响CO2加氢的重组，而且可以明确排除催化剂被加热活化的可能性。催化剂在CO2加氢过程中的原位表征表明，振动激发CO2显著增强了催化反应。结合实验研究和密度泛函理论（DFT）计算的方法的一致性证实，振动激发的CO2直接与吸附在Pd位上的氢反应，同时由于邻近的Ga位而加速甲酸形成。DFT分析还推导出等离子体活化氢促进单齿甲酸酯分解的关键反应途径。这项工作使二氧化碳加氢催化剂的高可设计性对增值化学品的基础上电气化的化学过程通过NTP。
Using nonthermal plasma (NTP) to promote CO2 hydrogenation is one of the most promising approaches that overcome the limitations of conventional thermal catalysis. However, the catalytic surface reaction dynamics of NTP-activated species are still under debate. The NTP-activated CO2 hydrogenation was investigated in Pd2Ga/SiO2 alloy catalysts and compared to thermal conditions. Although both thermal and NTP conditions showed close to 100% CO selectivity, it is worth emphasizing that when activated by NTP, CO2 conversion not only improves more than 2-fold under thermal conditions but also breaks the thermodynamic equilibrium limitation. Mechanistic insights into NTP-activated species and alloy catalyst surface were investigated by using in situ transmission infrared spectroscopy, where catalyst surface species were identified during NTP irradiation. Moreover, in in situ X-ray absorption fine-structure analysis under reaction conditions, the catalyst under NTP conditions not only did not undergo restructuring affecting CO2 hydrogenation but also could clearly rule out catalyst activation by heating. In situ characterizations of the catalysts during CO2 hydrogenation depict that vibrationally excited CO2 significantly enhances the catalytic reaction. The agreement of approaches combining experimental studies and density functional theory (DFT) calculations substantiates that vibrationally excited CO2 reacts directly with hydrogen adsorbed on Pd sites while accelerating formate formation due to neighboring Ga sites. Moreover, DFT analysis deduces the key reaction pathway that the decomposition of monodentate formate is promoted by plasma-activated hydrogen species. This work enables the high designability of CO2 hydrogenation catalysts toward value-added chemicals based on the electrification of chemical processes via NTP.