Active sites behavior on Ru@MIL-101(Cr) catalysts to direct alcohol to acetals conversion, an in situ FT-IR study of n-butanol and butanal.

[Display omitted] • In situ FT-IR is performed to understand the DAAC reaction on Ru@MIL-101(Cr). • α and β peaks are used as probes of metal-MOF interface sites and metallic sites. • n-Butanol favors the interface sites while butanal prefers the Ru metallic sites. • In situ FT-IR studies complete dynamic spectra for more analysis of kinetics. • Provide an insight of extraordinary DAAC reaction performance on the catalyst. Comparing to homogeneous systems, direct alcohol to acetals conversion (DAAC) reaction through heterogeneous catalysts has obvious advantages of simple separation, less corrosion and waste. However, progress on this research is quite limited. Recently a breakthrough of Ru@MIL-101(Cr) catalyst was found with high selectivity and conversion for DAAC of aliphatic alcohol and diols towards desired products. In this study, time resolved in situ FT-IR was performed for capturing molecular-level information on the active sites of the catalysis system. Transients analysis of interaction between n-butanol/butanal and two active surface sites induced by Ru loading on MIL-101(Cr) provides key insight into the reaction, revealing that Ru@ MIL-101(Cr) confines the reaction to the ideal acidic sites between Ru nanoparticles and MIL-101(Cr) support for efficient process. [ABSTRACT FROM AUTHOR]