Patent ID: 7671229

Claim:
A process for hydrocyanating 1,3-butadiene over at least one nickel(0) catalyst having phosphorus ligands, the process comprising providing a mixture of from 60 to 90% by volume of 1,3-butadiene and from 40 to 10% by volume of n-butane, the mixture prepared by the following process steps: A) providing a feed gas stream comprising the n-butane; B) feeding the feed gas stream comprising n-butane into at least one first dehydrogenation zone and nonoxidatively catalytically dehydrogenating the n-butane to obtain a first product gas stream comprising n-butane, 1-butene, 2-butene, 1,3-butadiene, low-boiling secondary constituents and in some cases steam; C) feeding the product gas stream of the nonoxidative catalytic dehydrogenation and an oxygenous gas into at least one second dehydrogenation zone and oxidatively dehydrogenating the 1-butene and the 2-butene to obtain a second product gas stream comprising n-butane, 2-butene, 1,3-butadiene, hydrogen, low-boiling secondary constituents and steam, said second product gas stream having a higher content of 1,3-butadiene than the first product gas stream; D) removing the low-boiling secondary constituents and the steam to obtain a C 4 product gas stream substantially consisting of n-butane, 2-butene and 1,3-butadiene; E) feeding the C 4 product gas stream into a distillation zone and removing a 1,3-butadiene/n-butane mixture.