This method comprises passing a residual stream into a flash drum to form a gaseous overhead flow and liquid bottom flow, and feeding the bottom flow into a distillation column, It comprises cooling the overhead flow in a heat exchanger to form a cooled overhead flow. It comprises the extraction of a gaseous overhead stream at the head of the distillation column, and the formation of at least one effluent stream from the overhead stream and/or from the top stream. The separation of the cooled overhead flow comprises passing the cooled overhead flow into an absorber, and injecting a methane-rich stream into the absorber to place the cooled overhead flow in contact with the methane-rich 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 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 production of light olefins by cracking a feed comprising C4 and/or C5 hydrocarbons. The process combines a catalytic naphtha cracking unit with an olefin paraffin separation unit and/or an olefin cracking unit. Contacting a feed stream comprising C4 and/or C5 olefins with a catalyst at catalytic naphtha cracking conditions produces a cracked product of ethylene and propylene.

A process for production of light olefins by cracking a feed comprising C4 and/or C5 hydrocarbons. The process combines a catalytic naphtha cracking unit with an olefin paraffin separation unit and/or an olefin cracking unit. Contacting a feed stream comprising C4 and/or C5 olefins with a catalyst at catalytic naphtha cracking conditions produces a cracked product of ethylene and propylene.

A method for purification of a styrene-containing feedstock includes steps of introducing the styrene-containing feedstock into the middle of an extractive distillation column, and a solvent for the extractive distillation into the upper part of the column; discharging a raffinate oil from the top of the column, and a rich solvent rich in styrene from the bottom of the column. The rich solvent is then introduced into the middle of the solvent recovery column for vacuum distillation to obtain a crude styrene from the top of the solvent recovery column, and a lean solvent is discharged from the bottom of the solvent recovery column and recycled to the upper part of the extractive distillation column. A portion of the rich solvent is sent to a solvent purification zone for a liquid-liquid extraction using water to obtain a mixture of a styrene polymer and styrene.

A method for purification of a styrene-containing feedstock includes steps of introducing the styrene-containing feedstock into the middle of an extractive distillation column, and a solvent for the extractive distillation into the upper part of the column; discharging a raffinate oil from the top of the column, and a rich solvent rich in styrene from the bottom of the column. The rich solvent is then introduced into the middle of the solvent recovery column for vacuum distillation to obtain a crude styrene from the top of the solvent recovery column, and a lean solvent is discharged from the bottom of the solvent recovery column and recycled to the upper part of the extractive distillation column. A portion of the rich solvent is sent to a solvent purification zone for a liquid-liquid extraction using water to obtain a mixture of a styrene polymer and styrene.

A method for producing green olefins and green gasoline from renewable sources, the method including: providing CO.sub.2 and hydrogen as feed to produce methanol in a methanol reactor, to produce an MTO reaction effluent, reacting the MTO reaction effluent in a plurality of separation columns to separate hydrocarbons, wherein the plurality of separation columns includes a Deethanizer column, a Depropanizer column, and a Debutanizer column, hydrogenating a fraction of separated hydrocarbons in the Debutanizer column with the hydrogen in a hydrogenation reactor, wherein the fraction of separated hydrocarbons from the Debutanizer column includes C.sub.5+ hydrocarbons; producing the green gasoline and Liquefied Petroleum Gas (LPG) by stabilizing the hydrogenated hydrocarbons in a gasoline stabilizer column; and producing the olefins by separating ethylene from C.sub.2 hydrocarbons using a C.sub.2 splitter column and by separating propylene from C.sub.3 hydrocarbons using a C.sub.3 splitter column.

A method for producing green olefins and green gasoline from renewable sources, the method including: providing CO.sub.2 and hydrogen as feed to produce methanol in a methanol reactor, to produce an MTO reaction effluent, reacting the MTO reaction effluent in a plurality of separation columns to separate hydrocarbons, wherein the plurality of separation columns includes a Deethanizer column, a Depropanizer column, and a Debutanizer column, hydrogenating a fraction of separated hydrocarbons in the Debutanizer column with the hydrogen in a hydrogenation reactor, wherein the fraction of separated hydrocarbons from the Debutanizer column includes C.sub.5+ hydrocarbons; producing the green gasoline and Liquefied Petroleum Gas (LPG) by stabilizing the hydrogenated hydrocarbons in a gasoline stabilizer column; and producing the olefins by separating ethylene from C.sub.2 hydrocarbons using a C.sub.2 splitter column and by separating propylene from C.sub.3 hydrocarbons using a C.sub.3 splitter column.