| 摘要 |
A process for preparing butadiene from n-butane, comprising the steps of A) providing a feed gas stream a comprising n-butane; B) feeding the feed gas stream a comprising n-butane into at least one first dehydrogenation zone and nonoxidatively, catalytically dehydrogenating n-butane to obtain a gas stream b comprising n-butane, 1-butene, 2-butene, butadiene and hydrogen, with or without carbon dioxide and with or without steam; C) feeding the gas stream b and an oxygenous gas into at least one second dehydrogenation zone and oxidatively dehydrogenating 1-butene and 2-butene to obtain a gas stream c comprising n-butane, butadiene, hydrogen, carbon dioxide and steam, D) compressing in at least one first compression stage and cooling the gas stream c to obtain at least one condensate stream d 1 comprising water and a gas stream d 2 comprising n-butane, butadiene, hydrogen, carbon dioxide and steam, E) separating the gas stream d 2 by extractive distillation into a product stream e 1 consisting substantially of butadiene and a stream e 2 comprising n-butane, hydrogen, carbon dioxide and steam, F) compressing in at least one further compression stage and cooling the gas stream e 2 to obtain at least one condensate stream f 1 comprising n-butane and water, and a gas stream f 2 comprising n-butane, hydrogen and carbon dioxide, G) cooling the gas stream f 2 to obtain a condensate stream g 1 comprising n-butane and an offgas stream g 2 comprising carbon dioxide and hydrogen, H) removing water from the at least one condensate stream f 1 and, if appropriate, from the condensate stream g 1 by phase separation to obtain at least one recycle stream hi comprising n-butane and at least one wastewater stream h 2 , and recycling the at least one recycle stream h 1 into the first dehydrogenation zone.
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