Boosting the catalytic performance of core-shell structured Ru@Pd/SBA-15 in 2-ethyl-anthraquinone hydrogenation by tuning d-band center

Abstract

Core-shell Ru@Pd/SBA-15 catalysts with various atomic layer numbers of Pd were prepared by changing the Pd/Ru ratio and Pd coating temperature. The results of characterizations show that the compressive strain of Pd atoms and electron transfer from Ru to Pd result in a downward shift in the d-band center of core–shell catalysts. Density functional theory calculations further reveal that the reduced d-band center of Pd via strain and electronic effects weakens the adsorption ability of Pd. A roughly volcano-shaped correlation between the d-band center and 2-ethyl-anthraquinone (EAQ) hydrogenation activity is experimentally observed. The catalyst with Pd shell of 2 atomic layers provides medium adsorption strength for EAQ and hydrogenated product, thereby exhibiting the highest activity of 0.37 molH₂·gMet⁻¹·min⁻¹, with a selectivity of 97.3%. This work provides a facile strategy for optimizing hydrogenation performance by modulating the strain and electron effects between the Ru core and Pd shell through regulating the number of shell layers.