TY - JOUR
T1 - Enhanced Fe2O3 reducibility via surface modification with Pd
T2 - Characterizing the synergy within Pd/Fe catalysts for hydrodeoxygenation reactions
AU - Hensley, Alyssa J.R.
AU - Hong, Yongchun
AU - Zhang, Renqin
AU - Zhang, He
AU - Sun, Junming
AU - Wang, Yong
AU - McEwen, Jean Sabin
N1 - Publisher Copyright:
© 2014 American Chemical Society.
PY - 2014/10/3
Y1 - 2014/10/3
N2 - The synergistic catalysis in the hydrodeoxygenation of phenolic compounds over a Pd/Fe bimetallic surface has been well established. However, the nature of this synergy is still in part a mystery. In this work, we used a combined experimental and theoretical approach to understand a potential function of the surface Pd in the reduction of Pd/Fe2O3. This function of Pd was investigated via the comparison of the reduction properties as well as other physicochemical properties of samples synthesized by the reduction of Fe2O3 nanoparticles with and without surface Pd. Temperature-programmed reduction studies demonstrated the remarkable facilitation of reduction by addition of Pd, evidenced by a 150 °C shift toward lower temperature of the reduction peak of Fe3+. From X-ray photoelectron spectroscopy and theoretical calculation results, the interaction between Pd and the Fe2O3 surface occurs through the exchange of electrons with both the surface Fe and O atoms. This bonding between the Pd and surface oxide elements causes the Pd to partially donate electrons to the oxide surface, making the surface electrons more delocalized. This electron delocalization stabilizes the reduced oxide surfaces, as suggested by the TPR results and theoretical prediction. Therefore, the stabilization of the reduced Fe surface as well as the facilitated water formation by introduction of Pd is expected to significantly contribute to the Pd-Fe synergy in hydrodeoxygenation catalysis.
AB - The synergistic catalysis in the hydrodeoxygenation of phenolic compounds over a Pd/Fe bimetallic surface has been well established. However, the nature of this synergy is still in part a mystery. In this work, we used a combined experimental and theoretical approach to understand a potential function of the surface Pd in the reduction of Pd/Fe2O3. This function of Pd was investigated via the comparison of the reduction properties as well as other physicochemical properties of samples synthesized by the reduction of Fe2O3 nanoparticles with and without surface Pd. Temperature-programmed reduction studies demonstrated the remarkable facilitation of reduction by addition of Pd, evidenced by a 150 °C shift toward lower temperature of the reduction peak of Fe3+. From X-ray photoelectron spectroscopy and theoretical calculation results, the interaction between Pd and the Fe2O3 surface occurs through the exchange of electrons with both the surface Fe and O atoms. This bonding between the Pd and surface oxide elements causes the Pd to partially donate electrons to the oxide surface, making the surface electrons more delocalized. This electron delocalization stabilizes the reduced oxide surfaces, as suggested by the TPR results and theoretical prediction. Therefore, the stabilization of the reduced Fe surface as well as the facilitated water formation by introduction of Pd is expected to significantly contribute to the Pd-Fe synergy in hydrodeoxygenation catalysis.
KW - Pd-Fe
KW - bimetallic catalysts
KW - biomass conversion
KW - density functional theory
KW - enhanced oxide reduction
KW - hydrodeoxygenation
KW - oxide doping effects
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U2 - 10.1021/cs500565e
DO - 10.1021/cs500565e
M3 - Article
AN - SCOPUS:84907841961
SN - 2155-5435
VL - 4
SP - 3381
EP - 3392
JO - ACS Catalysis
JF - ACS Catalysis
IS - 10
ER -