Decomposition DCOOH

J.L. Falconer, and R J. Madix, Flash desorption activation energies DCOOH decomposition and CO desorption fromNi(l 10), Surf. Sci. 48, 393-405 (1975). 

Only a few publications have been devoted to the kinetic isotope effects in the decomposition of formic acid, and only the metals Ag and Au were investigated. The most extensive work was published by Block and Krai (21), who measured the rate of the decomposition of formic acid over silver wires between 190 and 250°C, using the isotopic compositions HCOOH, HCOOD, DCOOH, and DCOOD. The kinetic isotope effect a, which is defined as the number of times the reaction... 

DCOOH was decomposed at 100°C on Ni powder with about the same number of surface Ni sites as there were D-formic acid molecules in the gas phase. Less deuterium than hydrogen was formed in the gas phase, which points to the formation of an intermediate with excess D on the surface. On fresh powders the C02/H2 + D2 + HD ratio was greater than unity, but this was not so after one decomposition run had been carried out. Obviously only fresh nickel absorbed hydrogen. 

On Ni-films, as on powders, DCOOH decomposition resulted in an excess of hydrogen in the gas phase and HCOOD decomposition in an excess of D2, which again points to the formation of an intermediate in which the acid hydrogen atom is split off. 

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