Basf Se Corporation

Markus Neudert

Michael Huebner

Gerrit Waters

Hans-Guenter Wagner

Thomas Roussiere

Suman Thotla

Randolph Hugo

Randolf Hugo

The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture () in a plant comprising an etherification unit (), a first distillation unit (), an ether cleavage unit () and a second distillation unit (), the process comprising: (a) contacting the C4-hydrocarbon mixture () with a primary alcohol () and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether in the etherification unit (); (b) distilling the reaction mixture () from the etherification unit () in the first distillation unit (), a C4-hydrocarbon raffinate being withdrawn as the overhead product (), and the alkyl tert-butyl ether being withdrawn as the bottom product (); (c) vaporizing the bottom product from the first distillation unit () in an evaporator () obtaining a vapor stream (); (d) reacting the vapor stream () of step (c) in the presence of an acidic catalyst obtaining isobutene and the primary alcohol as reaction products in the ether cleavage unit (); (e) distilling the reaction mixture () from the ether cleavage unit () in the second distillation unit (), isobutene being withdrawn as the overhead product (), the primary alcohol and diisobutene being withdrawn as the bottom product () and being recycled to the etherification unit (); wherein a purge stream () containing high boiling components with a normal boiling point higher than that of the alkyl tert-butyl ether is withdrawn from the evaporator () in step (c).

Process for obtaining isobutene from a C4-hydrocarbon mixture

The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture () in a plant comprising an etherification unit (), a first distillation unit (), an ether cleavage unit () and a second distillation unit (), the process comprising: (a) contacting the C4-hydrocarbon mixture () with a primary alcohol () and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether as an intermediate product and diisobutene as a by-product in the etherification unit (); (b) distilling the reaction mixture () from the etherification unit () in the first distillation unit (), a C4-hydrocarbon raffinate being withdrawn as the overhead product (), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (), and vaporizing the bottom product () if it is withdrawn as a liquid; (c) reacting the vaporous bottom product () in the presence of an acidic catalyst obtaining isobutene and the primary alcohol as reaction products in the ether cleavage unit (); (d) distilling the reaction mixture () from the ether cleavage unit () in the second distillation unit (), isobutene being withdrawn as the overhead product (), the primary alcohol and diisobutene being withdrawn as the bottom product () and being recycled to the etherification unit (); the plant further comprising a byproduct separation unit () being fed by a bottom purge stream () of the first distillation unit () and/or by a part of the bottom product of the second distillation unit (), this feed stream () being split up in at least three byproduct streams wherein a first byproduct stream () is rich in diisobutene, a second byproduct stream () is rich in the primary alcohol, and a third byproduct stream () is rich in components with a normal boiling point higher than 110° C.

The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture () in a plant comprising an etherification unit (), a first distillation unit (), an ether cleavage unit () and a second distillation unit (), the process comprising: (a) contacting the C4-hydrocarbon mixture () with a primary alcohol () and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether as an intermediate product and diisobutene as a by-product in the etherification unit (): (b) distilling the reaction mixture () from the etherification unit () in the first distillation unit (), a C4-hydrocarbon raffinate being withdrawn as the overhead product (), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (), and vaporizing the bottom product () if it is withdrawn as a liquid: (c) reacting the vaporous bottom product () in the presence of an acidic catalyst obtaining isobutene and the primary alcohol as reaction products in the ether cleavage unit (): (d) distilling the reaction mixture () from the ether cleavage unit () in the second distillation unit (), isobutene being withdrawn as the overhead product (), the primary alcohol and diisobutene being withdrawn as the bottom product () and being recycled to the etherification unit (); the plant further comprising a byproduct separation unit () being fed by a bottom purge stream () of the first distillation unit () and/or by a part of the bottom product of the second distillation unit (), wherein a diisobutene product stream rich in diisobutene is separated from this feed stream ().

The invention relates to a process for starting up a plant for removing isobutene from an isobutene-containing C4-hydrocarbon mixture, the plant comprising an etherification unit containing moist acidic ion exchange resin, a first distillation unit, an ether cleavage unit, and a second distillation unit. The invention further relates to a process for shutting down the plant from a stationary operation mode.

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Ludwigshafen, Germany

Markus Neudert