A process for the purification of isobutene from a C4 stream with at least 1-butene, 2-butene, isobutane and isobutene includes isomerizing 1-butene from a stream of material which is concentrated in isobutane and isobutene obtained from the C4 stream into 2-butene, using a catalyst in an isomerization reactor; supplying a product stream from the isomerization reactor to a rectification column; and providing a stream of material which is concentrated in isobutene. A processing facility is utilized for the purification of isobutene from the C4 stream.

Provided are a separation system for easily recovering normal butene from an olefin fraction including isobutene, isobutane, 1-butene, 2-butene, and normal butane, and a separation process system using the method. Since the separation system may easily convert 1-butene included in the olefin fraction to 2-butene, normal butene may be effectively separated and recovered by factional distillation and each recovered fraction may be easily refluxed even if the use of a reflux system using a refrigerant is reduced or excluded. Thus, economic efficiency may be improved and simultaneously, separation efficiency may be increased.

An isomerization catalyst for isomerizing a first straight-chain olefin to a second straight-chain olefin different therefrom in a double bond position in the presence of 20 ppm by volume or more of molecular oxygen more and/or water, comprising: Si; Al; and at least one metallic element selected from the Group 1 elements and the Group 2 elements, wherein the molar ratio of Si to Al (Si/Al) is 100 or less.

An isomerization catalyst for isomerizing a first straight-chain olefin to a second straight-chain olefin different therefrom in a double bond position in the presence of 20 ppm by volume or more of molecular oxygen more and/or water, comprising: Si; Al; and at least one metallic element selected from the Group 1 elements and the Group 2 elements, wherein the molar ratio of Si to Al (Si/Al) is 100 or less.

The present disclosure relates to processes for improved yields of propylene via metathesis, primarily from the conversion of C.sub.4 and C.sub.5.sup.+ olefins obtained from steam or fluid catalytic cracking of hydrocarbons. In particular, the present disclosure relates to processes for preparing propylene by improved isomerization of 1-butene to 2-butene relative to the metathesis reaction.

The present disclosure relates to processes for improved yields of propylene via metathesis, primarily from the conversion of C.sub.4 and C.sub.5.sup.+ olefins obtained from steam or fluid catalytic cracking of hydrocarbons. In particular, the present disclosure relates to processes for preparing propylene by improved isomerization of 1-butene to 2-butene relative to the metathesis reaction.

Provided are a separation method for easily recovering normal butene from an olefin fraction including isobutene, isobutane, 1-butene, 2-butene, and normal butane, and a separation process system using the method. Since the separation method according to the present invention may easily convert 1-butene included in the olefin fraction to 2-butene, normal butene may be effectively separated and recovered by factional distillation and each recovered fraction may be easily refluxed even if the use of a reflux system using a refrigerant is reduced or excluded. Thus, economic efficiency may be improved and simultaneously, separation efficiency may be increased.

A method for preparing polybutene includes the steps of: supplying a C4 mixture to an isomerization reactor in which (i) 1-butene is isomerized into 2-butene by a hydrogen isomerization reaction using an isomerization catalyst in an isomerization zone of the isomerization reactor and (ii) iso-butene and 2-butene are separated by fractional distillation in a fractional distillation zone; supplying a C4 mixture containing 2-butene which is separated in the isomerization reactor to a skeletal isomerization reactor, in which a part of normal-butene is skeletal isomerized into iso-butene by a skeletal isomerization reaction using a skeletal isomerization catalyst, and the obtained skeletal isomerization mixture is supplied and recycled to the isomerization reactor; and supplying (i) a raw material containing the iso-butene of high concentration and which is separated from the isomerization reactor and (ii) a polymerization catalyst to a polybutene polymerization reactor and thereby producing polybutene by a polymerization reaction.

A method for preparing polybutene includes the steps of: supplying a C4 mixture to an isomerization reactor in which (i) 1-butene is isomerized into 2-butene by a hydrogen isomerization reaction using an isomerization catalyst in an isomerization zone of the isomerization reactor and (ii) iso-butene and 2-butene are separated by fractional distillation in a fractional distillation zone; supplying a C4 mixture containing 2-butene which is separated in the isomerization reactor to a skeletal isomerization reactor, in which a part of normal-butene is skeletal isomerized into iso-butene by a skeletal isomerization reaction using a skeletal isomerization catalyst, and the obtained skeletal isomerization mixture is supplied and recycled to the isomerization reactor; and supplying (i) a raw material containing the iso-butene of high concentration and which is separated from the isomerization reactor and (ii) a polymerization catalyst to a polybutene polymerization reactor and thereby producing polybutene by a polymerization reaction.

A process for the purification of isobutene from a C4 stream with at least 1-butene, 2-butene, isobutane and isobutene includes isomerizing 1-butene from a stream of material which is concentrated in isobutane and isobutene obtained from the C4 stream into 2-butene, using a catalyst in an isomerization reactor; supplying a product stream from the isomerization reactor to a rectification column; and providing a stream of material which is concentrated in isobutene. A processing facility is utilized for the purification of isobutene from the C4 stream.