Decomposition of formic acid on titanium, vanadium, chromium, manganese, iron, cobalt, nickel, and copper

Abstract

The catalytic decomposition of formic acid has been investigated on evaporated films of the first transition-series elements from titanium to copper. Zero-order rates were observed for the first 15–20% of the decomposition with acid pressures of 30 mm Hg at temperatures, depending on the metal, in the range 100–300°. The product ratio CO₂/H₂ was always unity, but the CO₂/CO ratio varied in a twin-peaked manner across the series, with maxima at chromium and nickel. The latter product ratio was constant for a given metal irrespective of reaction temperature and percentage decomposition. Titanium was unique in that only dehydration of the acid was observed. The results are consistent with the occurrence, except with titanium, of a bimolecular transition state intermediate which breaks down to give both CO₂ and CO in proportions determined by the nature of the metal catalyst.