GASOLINE PRODUCTION PROCESS COMPRISING AN ISOMERIZATION STEP FOLLOWED BY AT LEAST TWO SEPARATION STEPS

• US 20170044447A1
• Filed: 04/20/2015
• Published: 02/16/2017
• Est. Priority Date: 04/29/2014
• Status: Active Grant

• Current Assignee: Axens
• Original Assignee: Axens
• Inventors: Pigourier, Jerome, Prevost, Isabelle, Watripont, Laurent, Martin, Pierre-Yves
• Granted Patent: US 10,113,121 B2
• Time in Patent Office: Days
• CPC Class Codes: C10G 2300/104 Light gasoline having a boiling range of about 20 - 100 °C
• CPC Class Codes: C10G 2300/1044 Heavy gasoline or naphtha having a boiling range of about 100 - 180 °C
• CPC Class Codes: C10G 2400/02 Gasoline
• CPC Class Codes: C10G 45/58 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 Class Codes: C10G 61/02 plural serial stages only
• CPC Class Codes: C10G 7/00 Distillation of hydrocarbon oils
• CPC Class Codes: C10L 1/06 for spark ignition
• CPC Class Codes: C10L 2200/0423 Gasoline
• CPC Class Codes: C10L 2290/543 Distillation, fractionation or rectification for separating fractions, components or impurities during preparation or upgrading of a fuel

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.

Claims

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., preferably in the range 110°

C. to 240°

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<sup>−

1</sup>, preferably 1 to 4 h<sup>−

1</sup>,

the catalysts used being constituted by a support of high purity alumina preferably 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],

2—

a second separation step [5], consisting of a separation column wherein the overhead and bottom products are the products from the unit, namely an overhead stream (19) which is rich in C6 branched compounds, a bottom stream (18), 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 isomerization process an exchange of heat is carried out between the 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, i.e. 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. The light naphtha isomerization process according to claim 1, in which the first separation step comprises just a single column [3], in which the stream of isopentane (15) leaves the column [3] overhead, the stream enriched in hydrocarbons which are heavier than pentanes (17) leaving from the bottom of said column [3] is supplied to the column of the deisohexanizer [5], and the intermediate withdrawal (stream 16) is recycled to the isomerization unit [1].

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 the condenser of the deisohexanizer [5] and either the reboiler of the depentanizer [4] or the 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].