CS276653B6 - A method for treating a gasoline fraction obtained by hydrocracking a petroleum vacuum distillate - Google Patents

Abstract

The solution describes the treatment of a gasoline fraction obtained by hydrocracking a petroleum vacuum distillate, in which high-octane lighter fractions are separated from light gasoline and the fraction containing π-hexane together with Cg-cyclanes including the remaining C7-hydrocarbons is reformed together with heavy cyclane gasoline, optionally with the addition of heavy hydrotreated gasoline from crude oil on a platinum-rhenium catalyst.

Description

The present invention relates to the improved use of light naphtha obtained by hydrocracking petroleum vacuum distillates by reforming in the presence of high-boiling hydrocarbons to the high-octane component of motor gasolines.

Increasing the production of light petroleum products is done by fission processes in which the raw materials are the high-boiling components of crude oil. Hydrocracking of vacuum distillates under a hydrogen pressure of between 10 and 30 MPa also leads to the formation of new gasoline fractions boiling up to 200 ° C, which are usually divided into light gasoline, i.e. a component boiling up to 90 to 100 ° C and high-boiling heavy gasoline. The resulting gasoline is highly naphthenic and contains homologues of cyclopentane and cyclohexane types of cyclans. As the boiling point increases, the octane VM number of this gasoline decreases from 78 to 50 units. The fraction boiling up to 100 ° C contains predominantly C 1 -C 4 hydrocarbons. For one-pass hydrocracking gasolines, the ratio of i- and n-pentanes corresponds to thermodynamic equilibrium and is about 3: 2. Methylpentanes and π-hexane are present in the hexane fraction, as well as methylcyclopentane and cyclohexane from cyclanes. Benzene is also present. In the C 1 -fraction, which is already divided between light and heavy gasoline, C 1 -alkanes predominate and the ratio between Cyccyclopentanes and methylcyclohexane shifts to the latter. The composition of light gasoline obtained by circulating fractions boiling above gasoline (above 180-200 ° C) to the hydrocracker is different: the ratio of i: n-hydrocarbons is significantly higher and the concentration of cyclopentane types in cyclans increases. Aromas are also declining. Heavy gasoline differs less. Light gasoline is mostly used as a medium octane component of motor gasolines, especially of lower quality grades. Its use for unleaded petrol is difficult.

The present invention provides a process for treating gasoline from hydrocracking to obtain a high octane component of gasoline. According to the invention, a process for treating the gasoline fraction obtained by hydrocracking a petroleum vacuum distillate carried out by direct passage with 20 to 80% conversion to fractions boiling below 360 ° C consists in separating light naphtha from hydrocracking boiling to 85-110 ° C into a fraction boiling to 60 to 65 ° C, containing butanes, pentanes and isohexanes and a residue containing n-hexane, C 8 -cyclanes and C 4 -hydrocarbons, constituting 30 to 70% by weight, of the original light naphtha, and this residue is combined with boiling naphtha. from 90 to 110 to 170 to 210 ° C in a volume ratio of 1: 3 to 10, the mixture is then reformed under medium hydrogen pressure in the presence of platinum-rhenium catalysts. In addition, heavy hydrotreated petroleum gasoline can be added to the reforming mixture in an amount of up to 80% by volume. The reforming of the mixture takes place in a three- to four-stage system in the presence of platinum-rhenium catalysts with a metal weight ratio of 1: 1 to 1: 3 at platinum concentration. between 0.2 and 0.35 wt. A reformate with an OČVM of 90 to 100 units is obtained.

The analysis of the process according to the invention shows the advantages of the new process. A light fraction is separated from the light naphtha obtained, which contains relatively high-octane components, pentanes and isohexanes. This light component has improved anti-knock properties and is suitable for direct blending into high-octane gasoline. Its quality is close to that of a low-temperature isomerizate. Cr and iC, alkanes give predominantly gaseous hydrocarbons during the reforming by hydrocracking. The rest of the light gasoline contains low octane n-hexane and isoheptanes and easily reformable cyclenes, especially cyclohexane. Reformation of these light hydrocarbons together with the heavy gasoline according to the invention prevents greater cleavage of the C 1-4 alkanes into gases. The n-hexane is isomerized to equilibrium with the isohexanes. Cycloalkanes then give benzene and toluene. It is also significant that upgrading the light fraction of hydrocracked naphtha itself by reforming would lead to deteriorated yields of liquid product under standard reforming conditions. The new procedure eliminates the loss of yield.

The following is a typical use case. Its terms illustrate the invention but do not limit its scope.

Example. From a vacuum petroleum distillate boiling predominantly above 360 ° C, a product in which 40% by weight was present was obtained by hydrocracking at a pressure of 17 MPa and a temperature of 360 ° C, fractions boiling up to 360 ° C. In the case of A (ordinary), all gasoline boiling up to 190 ° C and light and heavy gasoline were distilled from this product, the analyzes of which are given in Tab. 1.

CS 276653 Β 6 2

Tain analyzes of case 0 are also given, where part of the light gasoline was converted to heavy gasoline.

Both heavy gasolines were first reformed pilot plant on a Pt-Re-catalyst (0.3 wt.% Pt and 0.3 wt.% Re on alumina activated 1-1.2 wt.%, Chlorine) under the following conditions:

P = 2.5 MPa

LHSV = 1.5 h ^-1

H ₂ : CH = 5.5: 1 mol.

Temperatures of 498, 501 and 504 ° C were maintained on three successive reaction layers. Analyzes of the obtained products are given in tab.2.

The analyzes show that practically the same quality reformates according to OČVM were obtained, the reformate according to the invention has a lower boiling point and density. Their yields were practically the same.

Then each of the light gasolines was mixed with the appropriate reformate and the quality of the blends was assessed. It can be seen that the mixture according to the invention has a higher OČVM of 1.1 units. The heavier part of light gasoline (I) has been changed to reformate, whose octane number VM is 35 units larger than raw material I at high yield. For example, in the production of 8,000 t I, the octane pool in a gasoline refinery is increased by 8,000 x 35 = 280 kt octane and one precondition is created for reducing lead in gasoline.

The results from the quarterly operation unit were verified in a large-scale unit with a capacity of 20 t / h and the same yields and quality of reformate were achieved with both raw materials. Also the lightweight gasoline according to the invention had 5 units higher OČVM than the conventional light gasoline. During the process, hydrocracked gasoline was diluted with 55 ¾ by volume to 60 ¾ by volume of hydrotreated heavy naphtha from petroleum and reformed to OČVM 96 to 97 in a four-reactor system filled with a Pt-Re-catalyst with 0.3 ¾ by weight, each of metals on alumina. .

Table 1

Analyzes of light and heavy gasolines from hydrocracking

case 1 common according to 2 of the invention benzine light heavy light heavy d ₂ o (kg / m ^) 663 775 631 770 rain. curve ° C start. 29 103 24 83 10% vol. To 36 116 25 100 50% vol. 55 136 38 134 90% vol. 77 168 67 171 k. d. 92 190 70 187 OČVM 78.0 60.4 82.6 61.4 composition of hydrocarbons ¾ wt. ^C 4 13.8 0 24.0 0 iC ₅ 16.9 0 31.9 0 ¹ nC _g 11.8 0 21.6 0 ^ÍC 6 20.2 0 16.3 2.6 ňC ₆ 7.8 0.2 1.1 2.1

CS 276653 B 6

Table 1 - continued

McC ₅ 11.7 1.1 4.5 3.8 cCg 4.9 1.3 0 2.6 B 5.3 0.4 0 1.2 c ₇ + 7.6 97.0 0 87.7

Table 2

Analyzes of reformates from hydrocracking gasolines

case no. 1 2 benzine normal heavy according to the invention (Table 1, column 4) reformate yield% wt. 88.7 88.8 OČVM 96.5 96.5 ^d 20 786 784 start. rain. ° C 39 . 36 10% vol. To 78 75

Table 3

Gasoline from hydrocracked gasolines

gasoline 1 common 2 according to the invention composition (¾ vol.) light gasoline 17 12 reformat from tab. 2 83 88 characteristics: OČVM 93.6 94.7 d ₂ o (kg / ¹ ” ³ ) 765 768 Distillation point ° C 64 65

CS 276653 B 6 4

Claims (3)

PATENT CLAIMS A process for treating a gasoline fraction obtained by hydrocracking a petroleum vacuum distillate by direct passage with 20 to 80 ° conversion to fractions boiling below 360 ° C, characterized in that light hydrocracking gasoline boiling up to 85 to 110 ° C is distilled into a fraction boiling to 60 to 65 ° C containing butanes, pentanes and isohexanes and a residue containing n-hexane, C 2 -cyclanes and C 2 -hydrocarbons, forming 30 to 70% by weight, of the original light naphtha, and this residue is combined with boiling naphtha heavy naphtha. from 90 to 110 ° C to 170 to 210 ° C in a volume ratio of 1: 3 to 10 and the mixture is then reformed under medium hydrogen pressure in the presence of platinum-rhenium catalysts. 2. The process according to item 1, characterized in that the reforming mixture additionally comprises the addition of heavy hydrotreated petroleum gasoline in an amount of up to 80 ¾ vol. 3. The process according to items 1 and 2, characterized in that the reforming of the mixture takes place in a three- to four-stage system, in the presence of platinum-rhenium catalysts with a metal weight ratio of 1: 1 to 1: 3 at platinum concentrations between 0.2 and 0.35. ¾ wt.