Systems and methods for producing propylene using an MTBE synthesis raffinate are disclosed. An MTBE synthesis raffinate stream first passes through a molecular sieve to separate n-butane and isobutane from the rest of C.sub.4 hydrocarbons of the MTBE synthesis raffinate. The 1-butene in the rest of C.sub.4 hydrocarbons of the MTBE synthesis raffinate is then isomerized to form 2-butene. Therefore, the concentration of 2-butene in the subsequent propylene production process increases due to the separation of n-butane and isobutane and the isomerization of 1-butene, resulting in an improved reaction rate and reaction efficiency for propylene production.

Systems and processes disclosed may be used to produce a high purity isobutane stream and a high purity 1-butene stream from mixed C4 streams having disparate starting compositions.

Systems and processes disclosed may be used to produce a high purity isobutane stream and a high purity 1-butene stream from mixed C4 streams having disparate starting compositions.

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. A naphtha feed stream may be separated into a normal paraffin stream and a non-normal paraffin stream. An isomerization feed stream is taken from the non-normal paraffin stream and isomerized over an isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream. The isomerization effluent stream may be separated into a propane stream and a C4+ hydrocarbon stream optionally in a single column. The C4+ hydrocarbon stream may be recycled to the step of separating a naphtha feed stream.

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. A naphtha feed stream may be separated into a normal paraffin stream and a non-normal paraffin stream. An isomerization feed stream is taken from the non-normal paraffin stream and isomerized over an isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream. The isomerization effluent stream may be separated into a propane stream and a C4+ hydrocarbon stream optionally in a single column. The C4+ hydrocarbon stream may be recycled to the step of separating a naphtha feed stream.

A dividing wall column is used in an alkylation process flow scheme to fractionate an alkylate reactor effluent to produce an iso-butane-rich stream as a recycle feed for the alkylation reactor while also separating iso-butane, normal butane and alkylate as separate product streams depending on the reactor effluent composition. In an optional embodiment, the scheme may contain propane.

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. A naphtha feed stream may be separated into a normal paraffin stream and a non-normal paraffin stream. An isomerization feed stream may be taken from the non-normal paraffin stream and isomerized over an isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream. The isomerization effluent stream may be separated into a propane stream and a C4+ hydrocarbon stream optionally in a single column. The C4+ hydrocarbon stream may be recycled to the step of separating a naphtha feed stream.

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. A naphtha feed stream may be separated into a normal paraffin stream and a non-normal paraffin stream. An isomerization feed stream may be taken from the non-normal paraffin stream and isomerized over an isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream. The isomerization effluent stream may be separated into a propane stream and a C4+ hydrocarbon stream optionally in a single column. The C4+ hydrocarbon stream may be recycled to the step of separating a naphtha feed stream.

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.

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.