Structure–reactivity relationships in VO /TiO2 catalysts for the oxyhydrative scission of 1-butene and n-butane to acetic acid as examined by in situ-spectroscopic methods and catalytic tests

Abstract

Different VO x /TiO 2 catalyst have been catalytically tested and studied by in situ-spectroscopic methods (FT-IR, UV/vis, EPR) in the oxyhydrative scission (OHS) of 1-butene and n-butane to acetic acid (AcOH). While 1-butene OHS follows the sequence butane → butoxide → ketone → AcOH/acetate with a multitude of side products also formed, n-butane OHS leads to AcOH, CO x and H 2 O only. Water vapour in the feed improves AcOH selectivity by blocking adsorption sites for acetate. The admixture of Sb 2 O 3 was found to improve AcOH selectivity which is due to deeper V reduction under steady state conditions and lowering of surface acidity. VO x /TiO 2 catalysts with sulfate-containing anatase are the most effective ones. Covalently bonded sulfate at the catalyst surface causes specific bonding of VO x , stabilizes active V species and ensures their high dispersity.

Comparative study of propane dehydrogenation over V-, Cr-, and Pt-based catalysts: Time on-stream behavior and origins of deactivation

“…For comparative purposes, the spectrum of the catalyst reduced in H 2 (see Section 2.3) is also shown in this figure. An increase in the relative Kubelka-Munk function in the 420-800 nm range after 0.5 h in H 2 flow at 823 K is related to the reduction of V 5+ to V 4+ /V 3+ [28,38,39]. From this UV/Vis spectrum and our findings made in the in situ spectroscopic study of VO x /SiO 2 -TiO 2 redox behavior [39], we conclude that the changes in the UV/Vis spectra of VO x /MCM-41 during DH reaction are related to the formation of coke species.…”

Catalytic Performance of MIL‐88B(V) and MIL‐101(V) MOFs for the Selective Catalytic Reduction of NO with NH3

“…It can be seen that the ultraviolet absorption edge wavelength of MIL‐88B(V) was 490 nm, which was 15 nm higher than the 475 nm ultraviolet absorption edge wavelength of MIL‐101(V). Generally, the greater the ultraviolet absorption wavelength, the higher the degree of polymerization of the V species [35,43–44] . It can be inferred from the solid ultraviolet diffuse reflection results that the V species in MIL‐88B(V) had higher degree of polymerization and more V−O−V bonds, which may provide more acid sites in the SCR reaction.…”