Study on the Selective Hydrogenation of Butadiene in C<sub>4</sub>-Hydrocarbon Fraction (Part 2)

Abstract

Selective hydrogenation of butadiene in C4-hydrocarbon fraction in the presence of carbon monoxide in order to remove the butadiene and to prevent the isomerization of 1-butene has been studied. The following results were obtained.(1) The sensitivities of metal-alumina catalysts to carbon monoxide varied in order of Fe>Pt>Co>Pd>Ni. The selectivities of butadiene hydrogenation in the presence of carbon monoxide were almost quantitative over Pd, Co and Ni catalysts and somewhat low over Pt catalyst. The order of the magnitude of prevention effects for 1-butene isomerization by carbon monoxide was Pd>Ni>Pt∼Co. Consequently, Pd-alumina was found to be most favorable catalyst in the selective hydrogenation of butadiene without 1-butene isomerization in the presence of carbon monoxide.(2) Reaction conditions over Pd-alumina catalyst were investigated. Higher pressure and carbon monoxide concentration were effective for the prevention of 1-butene isomerization. Complete removal of butadiene was possible in the lower range of the pressure and carbon monoxide concentration than the prevention of 1-butene isomerization. Higher temperature was preferable to raise hydrogenation activity, whereas lower temperature was desired to prevent 1-butene isomerization. Optimum temperature was found to be nearly in 100°C, and about 90% of residual 1-butene and the complete removal of butadiene were achieved simultaneously at this temperature.(3) The action of carbon monoxide to the Pd catalyst in the hydrogenation was reversible. The hydrogenation selectivity and residual 1-butene in the product varied rapidly by addition or removal of carbon monoxide.