Study on the Selective Hydrogenation of Butadiene in C4-Hydrocarbon Fraction (Part 3)

Selective hydrogenation of butadiene to prepare 1-butene in a good yield has been studied over several group VIII metal catalysts in the presence of carbon monoxide. The following results were obtained.(1) In the presence of carbon monoxide, the selectivities of butadiene hydrogenation to n-butenes were kept nearly 100% until high conversion of butadiene over the various metal catalysts.(2) The selectivities of 1-butene and the trans-2-butene/cis-2-butene ratios did not change with the variation of the butadiene conversion over various metal catalysts and the selectivities of 1-butene over these catalysts were rebresented in the following order: Pt>Ir>Ph∼Ru>Pd>Ni and the order of trans-2-butene/cis-2-butene ratios were Pd>>Ir>Ni>Ru∼Ir>Pt. It was considered that 1-butene and 2-butenes were formed only by 1.2- or 1.4-addition of H2 on butadiene and the isomerization of 1-butene to 2-butenes did not proceed until butadiene disappeared.(3) Platinum-alumina catalyst showed very high 1-butene selectivity but resulted 1-butene was isomerized to 2-butenes when the butadiene conversion exceeded 90%. On the other hand, palladium-alumina catalyst showed somewhat lower 1-butene selectivity but no isomerization was observed. As a result, 1-butene could be produced in a good yield from butadiene using platinum-alumina catalyst followed by palladium-alumina catalyst in the presence of carbon monoxide in H2.