The invention relates to a method for producing hydrocarbon products which comprises preparing a hydrocarbon stream (C4) which predominantly comprises branched and unbranched hydrocarbons each having four carbon atoms. A first and a second partial stream (i-C4, n-C4) are obtained from this stream (C4), the first partial stream (i-C4) predominantly comprising branched hydrocarbons with four carbon atoms and the second partial stream (n-C4) predominantly comprising unbranched hydrocarbons with four carbon atoms. The method further comprises the steam cracking of at least part of the first partial stream (i-C4) at a first, higher cracking severity and at least part of the second partial stream (n-C4), at a second, lower, cracking severity.

The invention relates to a method for producing hydrocarbon products which comprises preparing a hydrocarbon stream (C4) which predominantly comprises branched and unbranched hydrocarbons each having four carbon atoms. A first and a second partial stream (i-C4, n-C4) are obtained from this stream (C4), the first partial stream (i-C4) predominantly comprising branched hydrocarbons with four carbon atoms and the second partial stream (n-C4) predominantly comprising unbranched hydrocarbons with four carbon atoms. The method further comprises the steam cracking of at least part of the first partial stream (i-C4) at a first, higher cracking severity and at least part of the second partial stream (n-C4), at a second, lower, cracking severity.

The present invention relates to a process for treating an effluent obtained from an oligomerization step in a vaporization step. In particular, the oligomerization step is a step for dimerization of ethylene to 1-butene with a nickel-based catalytic system.

The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture (1) in a plant comprising an etherification unit (3), a first distillation unit (5), an ether cleavage unit (8) and a second distillation unit (10), the process comprising: (a) contacting the C4-hydrocarbon mixture (1) with a primary alcohol (2) 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 (3): (b) distilling the reaction mixture (4) from the etherification unit (3) in the first distillation unit (5), a C4-hydrocarbon raffinate being withdrawn as the overhead product (6), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (7), and vaporizing the bottom product (7) if it is withdrawn as a liquid: (c) reacting the vaporous bottom product (7) in the presence of an acidic catalyst obtaining isobutene and the primary alcohol as reaction products in the ether cleavage unit (8): (d) distilling the reaction mixture (9) from the ether cleavage unit (8) in the second distillation unit (10), isobutene being withdrawn as the overhead product (11), the primary alcohol and diisobutene being withdrawn as the bottom product (12) and being recycled to the etherification unit (3); the plant further comprising a byproduct separation unit (15) being fed by a bottom purge stream (13) of the first distillation unit (5) and/or by a part of the bottom product of the second distillation unit (10), wherein a diisobutene product stream rich in diisobutene is separated from this feed stream (13, 14).

The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture (1) in a plant comprising an etherification unit (3), a first distillation unit (5), an ether cleavage unit (8) and a second distillation unit (10), the process comprising: (a) contacting the C4-hydrocarbon mixture (1) with a primary alcohol (2) 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 (3); (b) distilling the reaction mixture (4) from the etherification unit (3) in the first distillation unit (5), a C4-hydrocarbon raffinate being withdrawn as the overhead product (6), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (7), and vaporizing the bottom product (7) if it is withdrawn as a liquid; (c) reacting the vaporous bottom product (7) in the presence of an acidic catalyst obtaining isobutene and the primary alcohol as reaction products in the ether cleavage unit (8); (d) distilling the reaction mixture (9) from the ether cleavage unit (8) in the second distillation unit (10), isobutene being withdrawn as the overhead product (11), the primary alcohol and diisobutene being withdrawn as the bottom product (12) and being recycled to the etherification unit (3); the plant further comprising a byproduct separation unit (15) being fed by a bottom purge stream (13) of the first distillation unit (5) and/or by a part of the bottom product of the second distillation unit (10), this feed stream (14) being split up in at least three byproduct streams wherein a first byproduct stream (16) is rich in diisobutene, a second byproduct stream (17) is rich in the primary alcohol, and a third byproduct stream (18) is rich in components with a normal boiling point higher than 110 C.

The invention relates to a process for purifying a raw C4-hydrocarbon mixture comprising at least 2% by weight of isobutene, at least 23% by weight of butenes other than isobutene, less than 3% by weight of butadienes, at least 1.5 ppm by weight of a catalyst deactivator selected from the group of polar nitrogen containing compounds and mixtures thereof, wherein the sum of all components in the C4-hydrocarbon mixture is 100% by weight, the process comprising the steps of (d) contacting the raw C4-hydrocarbon mixture in countercurrent flow with an aqueous stream in an extraction unit yielding an intermediate C4-hydrocarbon mixture, (e) withdrawing at least part of the intermediate C4-hydrocarbon mixture from the extraction unit, and (f) dewatering the withdrawn intermediate C4-hydrocarbon mixture to obtain a purified C4-hydrocarbon mixture having a content of the catalyst deactivator of at most 1 ppm by weight. The invention further 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.