The invention relates to a process for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream a comprising n-butenes, B) feeding the input gas stream a comprising n-butenes and a gas containing at least oxygen into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, water vapor, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b by contacting with a cooling medium in at least one cooling zone, the cooling medium being at least partly recycled and having an aqueous phase and an organic phase, Cb) compressing the cooled product gas stream b which may have been depleted of high-boiling secondary components in at least one compression stage, giving at least one aqueous condensate stream c1 and one gas stream c2 comprising butadiene, n-butenes, water vapor, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases; D) removing uncondensable and low-boiling gas constituents comprising oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases, as gas stream d2 from the gas stream c2 by absorbing the C.sub.4 hydrocarbons comprising butadiene and n-butenes in an absorbent, giving an absorbent stream laden with C.sub.4 hydrocarbons and the gas stream d2, and then desorbing the C.sub.4 hydrocarbons from the laden absorbent stream, giving a C.sub.4 product gas stream d1, E) separating the C.sub.4 product stream d1 by extractive distillation with a butadiene-selective solvent into a stream e1 comprising butadiene and the selective solvent and a stream e2 comprising n-butenes; F) distilling the stream e1 comprising butadiene and the selective solvent into a stream f1 consisting essentially of the selective solvent and a stream f2 comprising butadiene, wherein stage Cb) comprises at least two compression stages Cba) and at least two cooling stages Cbb) configured in the form of quench columns, the cooling in the cooling stages being effected by direct contacting with a biphasic cooling medium having an aqueous phase and an organic phase.

The invention relates to a process for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream a comprising n-butenes, B) feeding the input gas stream a comprising n-butenes and a gas containing at least oxygen into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, water vapor, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b by contacting with a cooling medium in at least one cooling zone, the cooling medium being at least partly recycled and having an aqueous phase and an organic phase, Cb) compressing the cooled product gas stream b which may have been depleted of high-boiling secondary components in at least one compression stage, giving at least one aqueous condensate stream c1 and one gas stream c2 comprising butadiene, n-butenes, water vapor, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases; D) removing uncondensable and low-boiling gas constituents comprising oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases, as gas stream d2 from the gas stream c2 by absorbing the C.sub.4 hydrocarbons comprising butadiene and n-butenes in an absorbent, giving an absorbent stream laden with C.sub.4 hydrocarbons and the gas stream d2, and then desorbing the C.sub.4 hydrocarbons from the laden absorbent stream, giving a C.sub.4 product gas stream d1, E) separating the C.sub.4 product stream d1 by extractive distillation with a butadiene-selective solvent into a stream e1 comprising butadiene and the selective solvent and a stream e2 comprising n-butenes; F) distilling the stream e1 comprising butadiene and the selective solvent into a stream f1 consisting essentially of the selective solvent and a stream f2 comprising butadiene, wherein stage Cb) comprises at least two compression stages Cba) and at least two cooling stages Cbb) configured in the form of quench columns, the cooling in the cooling stages being effected by direct contacting with a biphasic cooling medium having an aqueous phase and an organic phase.

A method of producing a fuel additive includes: passing a raffinate stream comprising C4 hydrocarbons through a hydrogenation unit, forming a first process stream; passing the first process stream through an extractive distillation unit, forming a C4 olefin stream; passing the C4 olefin stream through a stripper column, forming a purified C4 olefin stream; and forming the fuel additive by passing the purified C4 olefin stream through a hydration unit.

A method of producing a fuel additive includes: passing a raffinate stream comprising C4 hydrocarbons through a hydrogenation unit, forming a first process stream; passing the first process stream through an extractive distillation unit, forming a C4 olefin stream; passing the C4 olefin stream through a stripper column, forming a purified C4 olefin stream; and forming the fuel additive by passing the purified C4 olefin stream through a hydration unit.

A method of producing a fuel additive includes: passing a raffinate stream comprising C4 hydrocarbons through a hydrogenation unit, forming a first process stream; passing the first process stream through an extractive distillation unit, forming a C4 olefin stream; passing the C4 olefin stream through a stripper column, forming a purified C4 olefin stream; and forming the fuel additive by passing the purified C4 olefin stream through a hydration unit.

A nonlimiting example method for producing a diesel boiling range composition comprises: oligomerizing an ethylene stream to a C4+ olefin stream in a first olefin oligomerization unit, wherein the C4+ olefin stream contains no greater than 10 wt% of methane, ethylene, and ethane combined in a first oligomerization; and wherein the ethylene stream contains at least 50 wt% ethylene, at least 2000 wppm ethane, no greater than 1000 wppm of methane, and no greater than 20 wppm each of carbon monoxide and hydrogen; oligomerizing the C4+ olefin stream and a propylene/C4+ olefin stream in a second oligomerization unit to produce an isoolefinic stream; wherein at least a portion of the isoolefinic stream is used to create the diesel boiling range composition.

A nonlimiting example method for producing a diesel boiling range composition comprises: oligomerizing an ethylene stream to a C4+ olefin stream in a first olefin oligomerization unit, wherein the C4+ olefin stream contains no greater than 10 wt% of methane, ethylene, and ethane combined in a first oligomerization; and wherein the ethylene stream contains at least 50 wt% ethylene, at least 2000 wppm ethane, no greater than 1000 wppm of methane, and no greater than 20 wppm each of carbon monoxide and hydrogen; oligomerizing the C4+ olefin stream and a propylene/C4+ olefin stream in a second oligomerization unit to produce an isoolefinic stream; wherein at least a portion of the isoolefinic stream is used to create the diesel boiling range composition.

A nonlimiting example method for producing a diesel boiling range composition comprises: oligomerizing an ethylene stream to a C4+ olefin stream in a first olefin oligomerization unit, wherein the C4+ olefin stream contains no greater than 10 wt% of methane, ethylene, and ethane combined in a first oligomerization; and wherein the ethylene stream contains at least 50 wt% ethylene, at least 2000 wppm ethane, no greater than 1000 wppm of methane, and no greater than 20 wppm each of carbon monoxide and hydrogen; oligomerizing the C4+ olefin stream and a propylene/C4+ olefin stream in a second oligomerization unit to produce an isoolefinic stream; wherein at least a portion of the isoolefinic stream is used to create the diesel boiling range composition.

An extractive distillation column system contains a combination column and a side rectification column. A process can be used for separation of butenes from C4-hydrocarbon streams using the extractive distillation column system.

An extractive distillation column system contains a combination column and a side rectification column. A process can be used for separation of butenes from C4-hydrocarbon streams using the extractive distillation column system.