Pd/FeOx催化剂动态生成Pdδ+-Fe2+界面高效催化逆水煤气变换反应

通过一系列原位、非原位表征,包括透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、程序升温解吸/还原/氧化(TPD/TPR/TPO)、X射线光电子能谱(XPS)等,系统地研究了Pd/FeOx催化剂的逆水煤气变换反应(RWGS)。以Pd(acac)2为前驱体合成了高度分散的Pd/FeOx催化剂,在400℃下,RWGS的CO2转化率高达29%,CO选择性超过98%,在目前文献中报道的催化剂中处于领先水平。通过原位表征方法,我们进一步研究了Pd/SiO2和Pd-Fe/SiO2,并明确指出了Pd-FeOx界面对促进RWGS反应的重要作用。准原位XPS实验进一步揭示了Pd/FeOx界面上动态形成的Pd^δ+-Fe^2+物种是高效催化C=O离解的活性位点。因此,实验结果证明,反应过程中动态形成的Pd^δ+-Fe^2+界面可以显著提高RWGS的活性和选择性,对CO2吸附、C=O解离和CO脱附都起到的促进作用。

Dynamic Formation of Pd^δ+?Fe^2+Interface Promoting Reverse Water Gas Shift Reaction over Pd/FeOx Catalyst

We systematically investigated Pd/FeOx for the reverse water gas shift(RWGS)reaction using a combination of ex situ and in situ characterizations,including transmission electron microscopy(TEM),Fourier-transform infrared(FTIR)spectroscopy,temperature-programmed desorption/reduction/oxidation(TPD/TPR/TPO),and X-ray photoelectron spectroscopy(XPS).A highly dispersed Pd/FeOx catalyst was synthesized using Pd(acac)2 as the precursor.The catalyst exhibited high activity,with CO2 conversion of~29%and CO selectivity ogreater than 98%at 400℃,which are among the highest values in the literature.Moreover,Pd/SiO2 and Pd-Fe/SiO2 were further studied to determine the significant role of the Pd-FeOx interface in promoting the RWGS reaction.Semi-in situ XPS revealed the dynamic formation of Pd^δ+-Fe^2+species at the Pd-FeOx interface;the species acted as highly active sites for CO2 dissociation.Our results also showed the formation of the Pd^δ+-Fe^2+interface during the RWGS reaction remarkably enhanced the activity and selectivity of the Pd-FeOx catalyst for the reaction,benefiting CO2 adsorption,C=O dissociation,and CO desorption.