Gasoline production process comprising an isomerization step followed by at least two separation steps

Patent metadata

Field	Value
Publication number	US-10113121-B2
Application number	US-201515307593-A
Country	US
Kind code	B2
Filing date	Apr 20, 2015
Priority date	Apr 29, 2014
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

The present invention describes a process for the production of high octane number gasoline by isomerization of a light naphtha cut, comprising two separation steps located downstream of the reaction step which can be used to improve the energy efficiency of said process.

First claim

The invention claimed is:

1. A process for the isomerization of a light naphtha, said process comprising an isomerization reaction step ( 1 ), said step being carried out under the following conditions:
a temperature in the range 100° C. to 300° C.,
a pressure of 2 to 35 bar (1 bar=0.1 MPa), and
a molar ratio of hydrogen/hydrocarbons in the range 0.1/1 to 1/1,
a space velocity of 0.5 to 10 h −1 ,
the catalysts used being constituted by a support of high purity alumina comprising 2% to 10% by weight of chlorine, 0.1% to 0.40% by weight of platinum, and optional other metals, said isomerization step being followed by a step ( 2 ) for stabilization of the reaction effluents, and by two steps for separation by distillation of the bottom stream obtained from the stabilization step ( 2 ) which are placed downstream of the stabilization step ( 2 ), the two separation steps being as follows:
1—a first step for separation by distillation (block ( 3 + 4 ) in order to separate the hydrocarbons containing 5 carbon atoms from heavier compounds sent towards the second section for distillation by separation ( 5 ), said first separation step producing the following 3 cuts: a) a cut which is enriched in isopentane ( 15 ) which is a product of the process, b) a cut which is enriched in n-pentane ( 16 ) which is recycled to the reaction section ( 1 ), and c) a cut which is enriched in hydrocarbons which are heavier than pentanes ( 17 ), which is directed towards a second separation step ( 5 ), ( 5 ), consisting of a separation column wherein the overhead stream ( 19 ) which is rich in C6 branched compounds and bottom stream ( 18 ), are the products from the unit and an intermediate cut ( 20 ) which is enriched in n-hexane, removed as a side stream which is recycled to the reaction section ( 1 ), in which in an isomerization process an exchange of heat is carried out between a condenser of one of the columns ( 3 ), ( 4 ) or ( 5 ) and the reboiler of one of columns ( 3 ), ( 4 ) or ( 5 ).

2. The light naphtha isomerization process according to claim 1 , in which the first separation step comprises two columns, a deisopentanizer ( 3 ) and a depentanizer ( 4 ), disposed in series, wherein the bottom stream ( 14 ) from the deisopentanizer ( 3 ) is supplied to the depentanizer ( 4 ), the stream of isopentane ( 15 ) leaves from the head of the column ( 3 ), a stream enriched in hydrocarbons which are heavier than pentanes ( 17 ) leaves from the bottom of the column ( 4 ) and is supplied to the deisohexanizer ( 5 ), and the overhead stream ( 16 ) from the column ( 4 ) is recycled to the isomerization unit ( 1 ).

3. A process for the isomerization of a light naphtha, said process comprising an isomerization reaction step ( 1 ), said step being carried out under the following conditions:
a temperature in the range 100° C. to 300° C.,
a pressure of 2 to 35 bar (1 bar=0.1 MPa), and
a molar ratio of hydrogen/hydrocarbons in the range 0.1/1 to 1/1,
a space velocity of 0.5 to 10 h −1 ,
the catalysts used being constituted by a support of high purity alumina comprising 2% to 10% by weight of chlorine, 0.1% to 0.40% by weight of platinum, and optional other metals, said isomerization step being followed by a step ( 2 ) for stabilization of the reaction effluents, and by two steps for separation by distillation of the bottom stream obtained from the stabilization step ( 2 ) which are placed downstream of the stabilization step ( 2 ), the two separation steps being as follows:
the first separation step comprises just a single column ( 3 ), in which a stream of isopentane ( 15 ) leaves column ( 3 ) overhead, a stream enriched in hydrocarbons which are heavier than pentanes ( 17 ) leaves from the bottom of said column ( 3 ) and is supplied to the column of a deisohexanizer ( 5 ), and an intermediate withdrawal (stream 16 ) is recycled to an isomerization unit ( 1 ), and
a second separation step ( 5 ), consisting of a separation column wherein the overhead stream ( 19 ) which is rich in C6 branched compounds and bottom stream ( 18 ) are the products from the unit, and an intermediate cut ( 20 ) which is enriched in n-hexane, is removed as a side stream which is recycled to the reaction section ( 1 ), in which in an isomerization process an exchange of heat is carried out between a condenser of one of the columns ( 3 ), ( 4 ) or ( 5 ) and the reboiler of one of columns ( 3 ), ( 4 ) or ( 5 ).

4. The light naphtha isomerization process according to claim 1 , in which the first separation step comprises the two columns ( 4 ) and ( 3 ) disposed in series in that order, the stream ( 12 ) obtained from the stabilization column ( 2 ) is supplied to the depentanizer ( 4 ) from which an overhead stream ( 21 ) leaves which is supplied to the deisopentanizer ( 3 ), and the bottom stream ( 17 ) from the depentanizer ( 4 ) which is enriched in hydrocarbons which are heavier than pentanes ( 17 ) is supplied to the deisohexanizer ( 5 ), the deisopentanizer ( 3 ) producing the overhead stream ( 15 ) which is rich in isopentane, and the stream ( 16 ) from the bottom, which is rich in normal pentane, which is recycled to the isomerization unit ( 1 ).

5. The light naphtha isomerization process according to claim 1 , in which an exchange of heat is carried out between a condenser of the deisohexanizer ( 5 ) and either a reboiler of the depentanizer ( 4 ) or a reboiler of the deisopentanizer ( 3 ), or both.

6. The light naphtha isomerization process according to claim 1 , in which an exchange of heat is carried out between the condenser of the depentanizer ( 4 ) and the reboiler of the deisopentanizer ( 3 ).

7. The light naphtha isomerization process according to claim 1 wherein the space velocity is 1 to 4 h −1 .

8. The light naphtha isomerization process according to claim 1 wherein the temperature is in the range 110° C. to 240° C.

Assignees

• Axens

Inventors

• Pigourier Jerome
• Prevost Isabelle
• Watripont Laurent
• Martin Pierre-Yves

Classifications

• C10G45/58 Primary

  to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins (C10G32/00 takes precedence; improving or increasing the octane number or aromatic content of naphtha C10G35/00) · CPC title

• C10L1/06

  for spark ignition · CPC title

• C10G61/02 Primary

  plural serial stages only · CPC title

• C10G2400/02

  Gasoline · CPC title

• C10G2300/1044

  Heavy gasoline or naphtha having a boiling range of about 100 - 180 °C · CPC title