Structure–reactivity relationships in VOx/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

摘要

Different VOx/TiO 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 and HO only. Water vapour in the feed improves AcOH selectivity by blocking adsorption sites for acetate. The admixture of SbO was found to improve AcOH selectivity which is due to deeper V reduction under steady state conditions and lowering of surface acidity. VO/TiO catalysts with sulfate-containing anatase are the most effective ones. Covalently bonded sulfate at the catalyst surface causes specific bonding of VO, stabilizes active V species and ensures their high dispersity.