Catalytic reactions of formate. 3. Noble metal chlorides as catalyst precursors for formic acid reactions

Abstract

Noble metal chlorides (‘RuCl3·xH2O’, ‘RhCl3·3H2O’, PdCl2 and ‘IrCl3·xH2O’) have been evaluated as catalyst precursors for the decomposition (HCO2H → H2 + CO2), dehydration (HCO2H → H2O + CO) and air oxidation (2HCO2H + O2 → 2H2O + 2CO2) of 88% HCO2H at 75–80 °C. RhCl3 under these conditions is an active oxidation catalyst but not an active decomposition catalyst. However, RuCl3 is an active decomposition catalyst but not an active oxidation catalyst. PdCl2 exhibits modest but detectable activity for all three formic acid reactions (decomposition, dehydration and oxidation). IrCl3 is a relatively active catalyst for all three HCO2H reactions. A comparison of the catalytic activities of the four noble metal chlorides for HCO2H decomposition under conditions where both the dehydration and air oxidation reactions are suppressed (4.4% aqueous HCO2H. Ar atmosphere) indicates the relative catalytic activity sequence: Ir ≫ Ru > Pd ≫ Rh (inactive).