Structure-reactivity relationships in VO_x/TiO_2 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 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 re-butane to acetic acid(AcOH).While 1-butene OHS follows the sequence bute-ne -> butoxide -> ketone -> AcOH/acetate with a multitude of side products also formed,n-butane OHS leads to AcOH,CO_x and H_2O only.Water vapour in the feed improves AcOH selectivity by blocking adsorption sites for acetate.The admixture of Sb_2O_3 was found to improve AcOH selectivity which is due to deeper V reduction under steady state conditions and lowering of surface acidity.VO/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.