Hydrogenation of buta-1,3-diene on supported metal catalysts in aqueous solution. Part 1.—Differences in the catalytic action of Al2O3-supported Pt, Pd, Rh and Ru catalysts

Abstract

Deuteration of buta-1,3-diene on Al₂O₃-supported Pt, Pd, Rh and Ru catalysts in 0.5 mol dm^–3 D₂SO₄ has been examined to see if there are differences in their catalytic action. The results are discussed on the basis of a simple common scheme in which butenes are formed via half-hydrogenated species and deuterium uptake proceeds by the reversible occurrence of two steps, namely (i) the formation of the half-hydrogenated species and (ii) the ionization of adsorbed hydrogen [X(a)⇌X⁺+e^–, X = H or D]. Simulation of the distribution of deuterium in the products leads to the conclusions that for the former step the rate follows the order Pd ≫ Pt > Rh > Ru and for the latter step the rate follows the order Pt ≫ Pd > Rh > Ru. H/D exchange is fastest on Pt and slowest on Ru.