Hydrogenation of alkadienes: IX. 1,3-butadiene hydrogenation catalyzed by rhenium and by sulfur-contaminated rhenium

Abstract

1,3-Butadiene hydrogenation has been catalyzed by rhenium film, rhenium wire, rheniumsilica, and rhenium supported on various aluminas. Products over uncontaminated catalysts were typically 1-butene, 54%; trans-2-butene, 30%; cis-2-butene, 13%; butane, 3%, this composition being fairly insensitive to reactant pressures and temperature. Such reaction at 150 °C was first order in initial hydrogen pressure and negative order in initial butadiene pressure; the activation energy over the range 60–155 °C was 35 − 4 kJ mol −1. The reaction of 1,3-butadiene with deuterium over rhenium-silica at 100 °C is reported in detail. From the kinetics, the product composition, and the distribution of deuterium in the products it is concluded that the mechanism of hydrogenation is adequately described by that proposed for the nickel-catalyzed reaction in Part III of this series (J. J. Phillipson, P. B. Wells and G. R. Wilson, J. Chem. Soc. A, 1351, 1969). The low butane yield, which is notable by comparison with the high yield obtained over the neighboring element osmium, is attributed to the measured low extent of hydrogen occlusion in rhenium. The distribution of deuterium in the butane shows that virtually no butene-butyl interconversions occur during butane formation and suggests that butane is formed at special sites. Contamination of rhenium by sulfur caused the 1:4 addition process to predominate and reduced the butane yield nearly to zero.