Synergetic effect of two halogen promoters present in acidic reaction medium or catalyst on the H2O2 formation (in H2-to-H2O2 oxidation) and destruction over Pd/C (or Al2O3) catalyst

摘要

A strong synergetic effect of two different halide anions (F- and I-,Cl- and I-,Cl- and Br-,and F_ and Br-) at optimum concentration in the catalyst or in an acidic reaction medium was observed in the H2-to-H2O2 oxidation over Pd/C,Pd/Al2O3,and halogenated Pd/Al2O3 catalysts.The synergetic effect promotes the net H2O2 formation by inhibiting the H2O2 decomposition and hydrogenation reactions.The effect is most pronounced for the combination of fluoride (or chloride) and iodide anions.The Br (1 wt%)-F (1 wt%)-Pd (5 wt%)/Al2O3 catalyst showed very high H2O2 yield (59%)/selectivity (60%) in the H2-to-H2O2 oxidation.