Assertion: butadiene | /r/HasProperty | free of n-butane
Facets:
value: essentially
type: DEGREE
Source sentences:
text: More specifically, we have now found that a butadiene-containing feedstream consisting essentially of butadiene, butylenes, n-butane, propylene, and vinyl acetylene can be effectively purified by introducing this feedstream into a separating zone comprising a first extractive distillation zone, extractively distilling said feedstream in said first extractive distillation zone with an extractant consisting essentially of a mixture of about 15 to 30 weight percent of acetone and about 85 to 70 weight percent of a sulfolane to produce an overhead stream comprising propylene, butylenes and n-butane, withdrawing from said separating zone a stream comprising butadiene and vinyl acetylene being essentially free of butylenes, n-butane and propylene, introducing said stream comprising butadiene and vinyl acetylene into a second extractive distillation zone, extractively distilling said stream comprising butadiene and vinyl acetylene with an extractant consisting essentially of a mixture of 15 to 30 weight percent of acetone and about 85 to 70 weight percent of a sulfolane, to produce an overhead stream consisting of butadiene free of vinyl acetylene and a bottoms stream comprising said extractant and vinyl acetylene, introducing said overhead stream of said second extractive distillation zone into a fractionation zone, fractionally distilling said overhead stream of said second extractive distillation zone in said fractionation zone to produce an overhead stream of essentially pure butadiene and recovering the stream of pure butadiene as the product of the process.