CA1238598A - Process for the preparation of hydrocarbon mixtures from an oil residue - Google Patents

Abstract

A B S T R A C T
PROCESS FOR THE PREPARATION OF HYDROCARBON
MIXTURES FROM AN OIL RESIDUE

Process for the preparation of hydrocarbon mixtures from an oil residue, comprising the following steps:
a) the oil residue is separated into a low-asphaltene hydrocarbon fraction and a high-asphaltene hydrocarbon fraction;
b) the low-asphaltene hydrocarbon fraction is subjected to cracking, in which hydrocarbon distillates are formed;
c) the high-asphaltene hydrocarbon fraction is partially combusted with the aid of an oxygen-containing gas, a gas mixture containing carbon monoxide and hydrogen being formed;
d) at least a part of the gas mixture containing carbon monoxide and hydrogen is subjected to catalytic hydrocarbon synthesis, synthetic hydrocarbons being formed;
e) at least a part of the synthetic hydrocarbons are mixed with at least part of the hydrocarbon distillates from the cracking.

Description

~23~5~9~
-1- 63293-2~82 PROCESS FOR THE PREPARATION OF HYDROCARBON
MIXTURES FROM AN OIL RESIDVE
The invention relates to a process for the preparation of hydrocarbon mixtures from an oil residue, characterized .in that a) the oil residue is separated into a low-asphaltene hydrocarbon fraction and a high-asphaltene hydrocarbon fraction;
b) the low-asphaltene hydrocarbon fraction is subjected to crack-.
ing, in which hydrocarbon distillates are formed;
c) the high-asphaltene hydrocarbon fraction is partially com-busted with the aid of an oxygen-containing gas, a gas mixture containing carbon monoxide and hydrogen being formed;
d) at least a part of the gas mixture containing carbon monoxide and hydrogen is subjected to catalytic hydrocarbon synthesis, synthetic hydrocarbons being formed;
e) at least a part of the synthetic hydrocarbons are mixed with at least part of the hydrocarbon distillates from the cracking.
Since the demand for light hydrocarbons is increasing and the demand for residual fractions is falling, it is important to prepare the maximum quantity of light products from a crude oil.
In the process according to the invention a complete conversion of an oil residue into lighter hydrocarbons is achieved.
The oil residue used in the present process is suitably obtained as byproduct in the atmospheric distillation o~ crude oil for the preparation of lighter hydrocarbon distillates, such as gasoline, kerosine and gas oil. ~ydrocarbon distillates are understood to mean the hydrocarbon fractions that can be separated ~.
.

~23~ 8 -la- 63293-2482 from a mixture by atmospheric distillation. In general, the distillates have a boiling point of up to 350C.
The process according to the invention is very suitable for application to residues obtained in the vacuum distillation of a residual fraction from atmospheric distillation of a crude oil. If a residue from the atmospheric distillation of a crude oil is available as feedstock for the process according to the invention, it is preferable to separate a vacuum distillate .~

~3L231~Si3~

from this residue by vacuum distillation, and to sub~ect the resulting vacuum residue to a separaeion into a low-asphaltene fraction and a high-asphaltene ~raction.
The residue can be suitably separated by solvent deasphalting lnto a deasphalted oil, which is low in asphaltenes, and an asphalt that is rich in asphaltenes.
In order to reduce the quantity oE high-asphaltene hydrocarbons to a minimum, so that a relatively small partial comb~stion reactor and a relatively small hydrocarbon synthesis reactor will suffice, the oil residue is preferably subJected to a pretreatment which reduces the quantity of the asphaltene-containing residue. For example, the residue can be subjected to thermal cracking. Preferably, before the separation into a low-asphaltene fraction and a high-asphaltene fraction, the oil residue is subjected to a catalytic hydrogen treatment, since hydrogen is absorbed by the residue during the hydrogen treatment, thus reducing the asphaltene content. ~uring the subsequent separation, for example by solvent deasphalting, a smaller high-asphaltene fraction is obtained. T~is means that a smaller partial combustion reactor is required.
Suitable catalysts for carrying out the hydrogen treatment are those comprising at least one metal chosen from the group formed by nickel and cobalt and additionally at least one metal chosen from the group formed by molybdenum and tungsten on an alumina-containing carrier. Very suitable catalysts for use in the hydrogen treatment are those comprising 2-6 parts by weight nickel or cobalt and 8-20 parts by weight molybdenum per 100 parts by weight alumina as carrier. ~he hydrogen treatment is preferably carried out at a temperature of 300-500C and in particular at 350-450C, a pressure of 50-300 bar and in particular 75-200 bar, a space velocity of 0.02-lO
g.g l.hour 1 and an U2/feedstock ratio Oe 100-5000 Nl.kg 1 and in particular 500-2000 Nl.kg 1.
Asphaltene-containing hydrocarbon mixture9 usually contain a substantial quantity of metals, especlally vanadium and nickel. IE these hydrocarbon mixtures are subjected to a catatytic treatment, Eor example a catalytlc hydrogen treatment to reduce the asphaltene content, these metals deposit on the catalyst used in the hydrogen treatment and thereby shorten their life.
For this reason, It is preferable to sub~ect asphaLtene-containing hydrocarbon mixtures with a vanadium ~ nickel content of more than 50 ppmw to , ,, ':

~, .

.. ..

~3~5~33 a demetallization process before contacting them with the catalyst employed in the catalytic hydrogen treatment. This demetallization can very suitabl~
be performed by cuntacting the asphal-tene-containing hydrocarbon mixture in the presence of 'nydrogen with a catalyst consisting for more than 80% of silica. Catalysts consisting entirely of silica, as well as catalysts contailling one or more metals with hydrogenation activity, in particular a combination of nickel and vanadiu~, on a carrier consisting mainly of silica, are suitable for thls purpose. If, in the process according to the invention, a catalytic demetallization in the presence of hydrogen ls applied to the asphaltene-containing feedstock, this demetallization can be carried out in a separate reactor. Since the catalytic demetallization and the hydrogen treatment for the reduction of the asphaltene content can be carried out under the same conditions, both processes can also very suitably be carried out in the same reactor, which contains successively a bed of the demetallization catalyst and a bed of the catalyst employed for the hydrogen treatment.
The product of the catalytic hydrogen treatment contains some light hydrocarbons, since there is also some formation of hydrocarbons with a boiling point of between 30 and 350C during the hydrogen treatment.
Preferably, the product of the catalytic hydrogen treatment is split into relatively light hydrocarboQs and a residue, which residue is separated into a low-asphaltene ancl a high-asphaltene hydrocarbon fraction. The relatively light hydrocarbons suitahly contaLn the products with a boiltng point below 350C, while the residue contains the products with a boiling point above 350C. The product of the catalytic hydrogen treatment is preferably split into relatively light hydrocarbons and a restdue by atmospheric distillation, the residue being subjected to vacllum or flash distillatton, after which the residue obtained from the last distillation is sub~ected to sotvent deasphalting, the asphalt, as high-a~phaltene hydrocarbon fraction, being fed to the partial combustion step, and the deasphalted oil, togetller with the distillate erom the vacuum or ~lash dist~llatioll, as low-asphaltene fraction, being fed to the cracking step.
In the process according to the invent~on, a solvent deasphalting is preferably employed in which an asphaltene-contalning feedstock is converted to a product ~rom which a deasphalted oil fraction and an asphalt fraction are separated. Suitable solvents for carrying out the deasphalting are . ~, .

~3~

paraffinic hydrocarbons with 3-6 carbon atvms per molecule, such as n-butane or mixtures thereof, e.g. mixtures of propane with n-butane and mixtures of n-butane with n-pentane. Suitable solvent/oil ratios are between 7:1 and 1:1 and in particular between 4:1 and 1:1. The deasphaltin~ is preferably carried out at a pressure of between 20 and 100 bar. If n-butane is used as solvent, the deasphalting is preferably carried out at a pressure of 35-45 bar and at a temperature of 100-150C.
~ he resulting low-asphaltene hydrocarbon fraction is then cracked to lighter hydrocarbon distillates. Since the gasoline fraction, obtained by catalytic cracking, is of good to very good quality, the cracking is preferably a catalytic cracking. Although thermal cracking doe~9 admittedly, give a reasonable gasoline fraction (pyrolysis gasoline), the presence of dienes in the gasoline, which can cause gum formation, necessitate the selective hydrogenatlon of these dienes to olefins. Pyrolysi~ gasoline therefvre requires an extra step. This makes it advantageous to employ cataIytlc cracking.
Catalytic cracking in the presence of hydrogen (hydrocracking) produces good quality distillates. However, hydrocracking requires relatively large quantLties of rather expensive hydrogen.
Gasoline preparation by catalytic cracking takes place by contacting the hydrocarbon mixture at a high temperature with a cracker catalyst. Catalytic cracking on a commercial scale is usually carried out as a continuous process employing equipment conslsting substantially of a vertical cra&king reactor and a catalyst regenerator. Hot regenerated catalyst Erom the regenerator is contacted with the oil to be cracked and the mixture i9 fed upwards through the cracking reactor. The catalyst deactivated by deposited coke is separated erom the cracked product and, after stripping, i9 transferred to the regenerator where the coke deposited on the catalyst is burnt off. The cracked product i9 separated into a llght fraction wtth a high content of C3 and C4 olefins, a gasoline fraction and several heavier Fractions, such as u Icerosine ~raction, a gas oil fraction and a heavy cycle oil. To raise the gaso1ine yield, the heavy cycle oil eraction can be recycled to the cracking reactor and the C3 and C4 olefins present in the light Eraction converted by alkylatton with lsobutane to alkylation gasoline. Preeerably, at least a part of the heavy cycle oil is added to the high-asphaltene hydrocarbon fraction and then partially combusted.
.~ .

' -.

:~' . ' .

Catalytic cracking on a commercial scale aims to balance the amount of heat released in the regenerator with the quantity of heat needed in the cracking reactor, so that tne process can be carried out without the need for installing extra heating or cooling equipmen~.
A variety of zeolitic catalysts can be used, both synthetic and natural, as cracker catalyst. Preferably, zeolites with a faujasite structure, such as natural faujasite, zeolite X or zeolite Y ~re used. The zeolites suitably have a very low alkali metal content; in this way the alkali metal ions can be exchanged with hydrogen or, suitably, with rare earth metals. The catalysts can, moreover, comprise a carrier, such as alumina, silica-alumina, magnesia, ~ilica-magnesia, titania, etc. A particularly preferred catalyst consists of zeolite Y in a matrix of amorphous silica-alumina.
Catalytic cracking is preferably carried out at a temperature of ~00 to 550C, a pressure of l to 10 bar and a space velocity of 0.25 to 5 kg feed per '~g catalyst per hour.
The partial comhustion of the high-as?haltene hydrocarhon fraction can take place with the aid of air or with oxygen-enriched air. In addition, steam i9 preferably also added as temperatur~ moderator to the mixture of high-asphaltene hydrocarbons and oxy~en-containing gas. ~oreover, the endothermic reaction of steam with carbon-containing material produces hydrogen, thus raising the hydrogen yield. Preferably, the high-asphaltene hydrocarbon fraction is partially combusted with oxygen in the presence of steam. The use of almost pure oxygen leads to the absence or near absence of nitrogen and/or other inert gas in the resulting gas mixture of carbon monoxide and hydrogen. This simplifies the processing of the gas mixture containing almost only carbon monoxide ancl hydrogen in the hydrocarbon synthesis.
Preferably, 0.5-1.5 Nm3 oxygen and 0.2-0.7 kg ~team per kg high-asphaltene hydrocarbon eraction is employed in the partlal combustion.
Suitable conditlonY tor carrying out the partlal combustion are a temperature of 1200-2000C, a pressure of 10-70 bar and a residence tlme of 1-10 sec.
In tile hydrocarbon synthesis, at least part o~ the gas containing carbon monoxide and hydrogen i9 contacted at elevated temperature and pressure with a catalyst. Such a catalyst can comprise a crystalline metal silicate.
Suit~ble metals in the mecal silicate are, for example, iron, aluminium, gallium, boron, chromium. It i9 advantageous to employ iron sllicate~ and , ~ ~ , . . .

~2;~

iron al~rniniu~ silic~tes which are described in 8ritish patent specification No. 1,55~,92~ in combination with a catalyst for the synthesis of methanol or dimethyl æther. Particularly advantageous i~s the use of a mi~tur~ of such a silicate and a catalyst for methanol svnthesis, such as a ZnO-Cr2O3 composition, as described in ~ritish patent specification No. 2,099,778. The employment of 3uch catalysts results in the synthesis of predominantly aromatic gasoline Eractions, which can be mixed wlth excellent results with the gas~line fraction obtained from the catalytic cracking, which fraction also contains aromatics. The kerosine ~ractions and gas oil fractions obtained ~rom the above-mentioned hydrocarbon synthesis, however, also contain aromatics, ~ust as the correspondin~ fractions obtained from the catalytic cracking. The arom~tics give rise to a low smoke point for the kærosine fractions and a lo~ cetane number for the gas oil/diesel fractions.
Preferably, the hydrocarbon ~ynthesis i9 therefore carried out wit1l a Fischer-Tropsch catalyst which cataly~ses the formation of high quality middle distillates (kero~ine, diesel oil, ~as oil). ~ suitable catalyst is one containing cobalt and at least one of the metals: zirconium, titanium and chrornium on silica, alumina or silica-alumina as carrier. The catalyst ?re~erably comprises 3-60 parts by weight cobalt and O.l-100 parts by weight ruthenium, zirconiu~, titanium and/or chromium per 100 parts by weight carrier. The catalyst is suitably ~abricated by impregnation oE the carrier ~lth a solution oE on~ or more compounds oE the metal or metals. This includes both a simllltaneolls impregnation of the carr~er with a solution colltalning all the metals concerned, and the successive applicatlon of the metals separately by impregnation. A very suitable catalyst can be made by kneadins tile carrier Witll one or more co~pounds o~ t~e metal or metal~ in the pre~ence of a liquid. Processes for preparing the catalyst~ are described in Sritish patent specificatLon ~o. 2,077,2S9 .
~ partLcularly preferred catalyst for thls purpose comprises 15-50 part~
by weLght cobalt and 0.1-40 part~ by weight zirconium per 100 parts by weight silica as carrier.

, ,. ~ , `' .

,.

Suitable conditLons for carrying out the hydrocarbon synthesis are a temperature of 200-250C, a pressure of 10-40 bar and a space velocity of 300-2000 Nl.l .hour Some of the fractions of the liquid hydrocarbons synthesized in the synthesis process are of excellent quality. The kerosine fraction and the gas oil ~raction in particular are excellent. The kerosine fraction contains mainly straight-chaLn hydrocarbon molecules, which results in a high smoke point. As the gas oil fraction also comprises ~ainly paraffinic hydrocarbons, thi~ Eraction has a high cetane number. The Presence of ?araffinic hydrocarbons, however, means that the gasoline fraction has a low octane number, but also a low sensibility (the difference between the research octane number alld the motor octane number). The hydrocarbon distillates from the cracking comprise a reasonable to very good gasoline fraction and reasonable middle distillate fractions in the case of hydrocracking and rather poor middle distillate fractions in the case of thermal or catalytic cracking. Although the aromatic and olefinic gasolines obtained by catalytic or thermal cracking have a high octane nunber, they also have a high sensibility.
Now, according to the invention, by mixing the fractions at ieast partly, hydrocarbon products are obtained which meet the product speciflcations. The good gasoline fraction from cracking ensures that the resulting gasoline fraction has an acceptable octane number, while the paraffinic synthetic gasoline ensures an acceptably low sensibility. ~te good middle distlllate fractions of the synthecic hydrocarbons ensure an acceptable quality o~ the resulting middle distillate ~ractions after -partial - mixing.
The advantages oE the Qrocess accordlng to the invention are therefore that an oil residue is fully converted into lighter hydrocarbon products and that these lighter hydrocarbon products are of good quality.
30 f the two ~a~ ~ractions obtained ~rom the cracklng and the hydrocarbon synthesis, the ~ractions having hydrocarbons with 3 and 4 carbon atoms (C3-C4 fractions) can be separated, which hydrocarbons can be used as LPG
(liquefied petroleum gas), a valuable automotive fuel. The isobutane present in the C~C4 fractions is very suLtably cortverted by alkylation with the oleEins ~rom the C3-C4 fractions from the cracking into valuable gasoline components, tilUS raising the gasoline yield. The lighter products, ;
, :

5~3 hydrocarbons with 1 or 2 carbon atoms, can be used as fuel or as feed for the chemical industry.
The products of -the hydrocarbon synthesis and the crack-ing can be mixed, partially or wholly, with one another before being fractionated. The advantage of this is that one fraction-ator is then enough. Preferably, however, the products of the hydrocarbon synthesis and the cracking are fractionated separately and corresponding fractions are mixed at leas-t partially with one another. In this way, the quantities of the corresponding fractions which are mixed with one another can be varied independ-ently. this makes it possible for just so much of the lesser quality fraction to be mixed with the corresponding good fraction that the quality of the resulting product always meets the specifications. It is advantageous if all the products are mixed with one another, providing that the quality of the products permits this. The product yield is then a maximum. The heavy fractions, i.e. fractions with a boiling point above that of gas oil, are preferably separated out of the products of the hydro-carbon synthesis and/or the cracking. The fractions, either mixed or umnixed, can then be returned to the cracking step.
Preferably, however, at least part oE the heavy fractions is fed to the partial combustion step.
IE just part of the mixture containing carbon monoxîde and hydrogen is subjected to the ca-talytic hydrocarbon synthesis, another part will preferably be subjected to a water gas shift reaction, in which the carbon monoxide in the mixture is converted ~ "

~2~
-8a- 63293-2482 with steam into carbon dioxide, hydrogen also being formed.
The water gas shift reaction can suitably be carried out by contacting the part of the gas mixture, together with 1-3 mol steam per mol carbon monoxide in the part of the gas mixture, with a catalyst containing iron, or copper and zinc. Preferably, the part of the gas mixture is contacted with a sulphidic catalyst containing molybdenum and nickel and/or coba].t on a aluminia carrier at a temperature of 200-500C and a pressure of 10~50 bar.
The water gas shift reaction can vary suitably be carried out in two steps: one at a high temperature, e.g. 350-450C and one at a low temperature, e.g. 200-300C.
The hydrogen formed from the water gas shift reaction can be recovered and used elsewhere. Preferably, the hydrogen is separated from the product ' '' _ 9 _ of the water gas shift reaction and at least a part of the hydrogen is used in a catalytic hydrogen treatment of the oil residue.
As pointed out above, heavy fractions are also formed in the hydrogen synthesis. To maximise the yield of hydrocarbon distillates, at least part 5 of the product .~f the hydrocarbon synthesis is preferably subjected to a catalytic hydrogen treatment. The preferred choice of feed for tlle hydrogen t~eat~ent is that part of the product whose initial boiling point is above the final boiling point of the gas oil fraction. The catalytic hydrogen treatment is carried out by contacting the fraction, at elevated temperature and pressure and in the presence of hydrogen, with a catalyst comprising one or more metals with hydrogenating activity on a carrier. Examples of suitable catalysts are sulphidic catalysts comprising nickel and/or cobalt and also molybdenum and/or tungsten on a carrier such as alumina or silica-alumina. However, the catalyst preferably used in the catalytic hydrogen treatment comprises one or more noble metals from Group VIIL on a carrier. The quantity of noble metal present on the carrier can vary within wide limits, but is usually 0.05-5 wt.%. The noble metals from Group VIII
which can be present on the carrier are platinum, palladium, rhodium, ruthenium, iridium and osmium, platlnum being preferred. If wished, two or more of these metals can be present in the catalysts. The quantity of noble metal from Group VIII present ln the cata1yst Ls preferably 0.1-2 wt.% and in particular 0.2-1 wt.~. Examples o~ suitable carriers Eor the n~ble metal catalysts are amorphous oxides of the elements from Group II, III and ~V, such as silica, alumina, magnesia and zirconia, as well as mixtures of these oxides, such as silica-alumlna, silica-magnesia and silica-zirconia, and zeolitic materials, such as mordenite and fau~asite. Aluminas and stlica-aluminas are preferred as carriers Eor the noble metal catalysts. A
very suitable noble metal catalyst for the present purpose ls a catalyst comprising one or more noble metals Erom Group VIII on a carrier consisting for 13-15 wt.% Oe alumina and Eor the rest of silica. SuitabIe conditions Eor carrying out the catalytic hydrogen treatmen-t are a tempera~ure of 175-400C~ a hydrogen partial pressure of 10-250 bar, a space velocity of 0.1 5 kg.l l.hour 1 and a hydrogen/oil ratio of 100-5000 Nl.kg 1. The catalytic hydrogen treatment is preferably carried out under the Eollowing conditions: a temperature of 250-350C, a hydrogen partial pressure of 25-150 bar, a space velocity of 0.25-2 kg.l l.hour 1 and a hydrogen/oil ratio of 250-2500 Nl.kg 1, . .

.1 ~3~5~
. -- 10 --The hydrogen needed in this treatment is suitably obtained from the water gas shift reaction, described above.
The invention ~ill now be further illustrated with reference to the schematic figure, whicll does not, incidentally, limit the invention in any way.
A vacllum residue containing asphal~enes is passed via a pipe 1 to a catalytic hydrogen treatment zone 2, where it is contacted with hydrogen supplied via a pipe 4. The treated residue is transported via a pipe 3 to an atmospheric distillation unit 5, where it is separated into lighter products which leave via a pipe 6 and a residue which leaves via a pipe 7. Altholl~h the figure indicates that all light products leave via a single pipe, light prodllcts can, o~ course, also be separated into several fractions in distillation unit S and discharged separately.
The atmospheric residue is passed via pipe 7 to a flflsh distillation unit 8, where A Elash distillate is separated and passed via a pipe 9, and a flash distillation res1due is ohtained that is passed via a pipe 10 out of unit ~ to a deasp~alting unit 11. In this unit 11 a low-asphaltene t~easphalted oll is obtained with aid of a solvent, which oil is discharged via a pipe 12 and mixed with the flash distillate from pipe 9 in a pipe 13.
Tl~e asphalt obtained from deasphfllting is discharged via a pipe 22.
The mixture o~ flash distillate and deasphalted oil passes to a catalytic cracking unit 14. The product obtained fro~ this unit passes via a pipe 15 to an atmospheric dlstillation unil 16 where it is separated into a gas fraction, discharged via a pipe 20, a gasoline fraction, di3charged via a pipe 17, a kerosine fractlon, discharged vla a pipe 18, a gas oil fraction, discharged via a plpe 19 and a heavy cycle oil fraction, discharged via a pipe 21.
The keuvy cycle oil Ln pipe 21 is added to the asphalt erom pipe 22. To this L~ added another heavy hydrocarbon fraction, arriving via a pipe 23.
The mixture thus obtalned, whlch is rich in asphaltenes, is passed via a pipe 24 into a gAsi~lcation unLt 25, where it i~ partially combusted with oxygen, supplied via a pipe 26, and steam, supplied via a pipe 27, a gas mixture being formed comprising carbon monoxide and hydrogen, which mixture leaves unit 25 via a pipe 2~. Part of the mixture ~lowing ln pipe 28 is tapped off via a pipe 29 leading to a water gas shift unit 45. ~The remaining part of the ga~ mixture is pasxed via a pipe 30 into a catalytic hydrocarbon ~%~ Y~

synthesis zone 31 and there converted into synthetic hydrocarbons which are discharged via a pipe 32. To these hydrocarbons are added via a pipe 35 the product of a catalytic hydrogen treatment, carried out in a unit 42. The mixture passes via a pipe 33 to an atmospheric distillation unit 34. There hydrocarbons are separated into a ga~s fraction, discharged via a pipe 36, a gasoline fraction, discharged via a pipe 37, a kerosine fraction, discharged via a pipe 33, a gas oil fraction, discharged via a pipe 39 and a re~idual fraction, discharged via a pipe 40. ~le residual fraction in pipe 40 is split into a stream which is added via pipe 23 to the high-asphaltene feed, and into a stream which is fed via a pipe 41 to the catalytic hydrogen treatment unit ~2. The hydrogen needed for hydrogen treatment is supplied via a pipe 43.
In a water gas shift zone 45, a part of the gas mixture containing carbon monoxide and hydrogen is, with the aid of steam supplied via a pipe 46, converted into hydrogen and carbon dioxide. The hydrogen is discharged through a pipe 44 and split into two sub-streams. One sub-stream is passed via pipe 43 to hydrogen treatment unit 42, and the other via plpe 4 to hydrogen treatment unit 2.
The gasoline fraction in pipe 17 is mixed with the gasoline fraction from pipe 37, resulting in a fraction which is discharged as automotive fuel via a pipe 47. The two kerosine fractions in pipes 18 and 38 are mixed, and the two gas oLl fractions in pipes 19 and 39 are mixed, resulting in a kero~ine product in a pipe 48 and a gas oil product in a pipe 49.
EXAMPLE
A procesY was carried out according to a process flow she~t as shown in figure, except that the resldual fraction obtained erom the hydrocarbon synthesis was subjected in its entlrety to a catalytic hydrogen treatment;
i.e. product stream 23 was equal to 0.
The catalytlc hydrogen treatment ln 2 wa~ carried out at a temperature of 400C, a pre~sure of 150 bar and a ~pace velocity of 0.2 k~.l l.hour 1, The feedstock was passed over a first catalyst bed comprising a catalyst with 0.5 pbw nickel and 2.0 phw vanadium perr 100 pbw of sllica, and then over a second bed ~ith a catalyst consisting of 4.0 pbw nickel and L4.0 pbw molybdenum per 100 pbw alumina.
The deasphalting in 11 was carried out at 120C and 40 bar with butane as solvent and with a solvent/oil weight ratio of 2.

'' ;' .

The catalytic cracking in lS took place with a catalyst consisting of zeolite Y in a silica-alumina matrix at a temperature of 500C, a pressure of

2 bar, a space velocity of 4 kg oil per kg catalyst per hour, a catalyst/oil weight ratio of 3 and a catalyst regeneration speed OL 1 kg catalyst perr 1000 kg oil.
T~e high-asphaltene fraction was partially combusted in 25 at a temperature of 1300C ~nd a pressure of 30 bar.
The catalytic 'nydrocarbon synthesis in 31 was carried out with a catalyst prepared by impregnation and comprising 25 pbw cobalt, 12 pbw zirconium and 10() pbw æilica with a catalyst surface areu of 100 m2/ml. The temper~ture was 215C, the pressure 25 bar, and the space velocity 600 Nl.l .hour In 42 the catalytic hydrogen treatment took place at 325C, 30 bar and a space velocity of 2 kg.l l.hour 1.
The catalyst employed comprised 0.8 wt.~ pla'tinum on silica-alumina.
The water gas shiEt unit 45 comprised two reactors driven adiahatically at pressure of 28 bar. In the Eirst reactor the average temperature was 410C
and a catalyst was usei consisting oE chromium oxlde promoted by Fe304.
In the second reactor the average temperature was 2;0C and a catalyst was used consisting Of a combi'natlon of copper and zinc oxide.
The Eollowing product streams were used in the process accordiag to the Example:

,, .

~;~3~

(parts by weight/
unit of time) 1: vacuum residue 100

3: product of hydroge~ treatment 102

4: hydrogen 2 6: atmospheric distillate 29 7: atmospheric residue 74 9: flash distillate 36 10: flash eesidue 38 12: deasphalted oil 22 13: mixture of 9 and 12 58 15: cracked product 54.5 17: gasoline fraction 29 1.3: kerosine fractlon 0.9 19: gas oil Eraction 7-3 2n: gas fraction 8.1 21: heavy cycle oil fraction 8.7 22: asphalt . 16 24: mixture of 21 and 22 24.7 20: oxygen 25 27: steam 11 23: gas mixture contalning C0 + H2 (98 vol.% H2 + C0) 46 29: sub-stream of 28 lS.S
30: fe~d for hydrocarbon synthesis 30.5 32: synthetic hydrocarbons 3.2 33: mixture of 32 aod 35 14.2 35: product of hydrocarbon tr~atment 36: gas eraction 1.2 37: gasoline fraction 3.3 33: kerosine fraction 2.4 3~: gas oil eraction 3.3 40: residuat fraction G
41: sub-stream oE residual eraction 6 43: hydrogen 0.03 44: hydrogen 2 ,1 . , (?artS by weight/
unit of time) 46: steam 27 47: resulting gasoline product 30.2 4~: resulting kerosine product 3.3 49: resu1ting gas oil product 11.1 The gasoline fraction from pipe 17 had, wlthout addition of lead, a researcll octane number of 92 and a sensibility o~ 13. I~.e gasoline fraction from pipe 32 had a research octane number of 45 and a sensibility of 1. The resulting gasoline product had an octane number of 30 and a sensibility of 12. Mixing therefore produced a gasoline product with a favourable octane number and an acceptable senslbility.
The smoke point of the kerosine fraction in pipe 1~ was unacceptably low, vi~. ~ mm; that of kerosine fraction in pipe 33 was exceptionally high, Vi2. more than 50 mm. The product in pipe 44 had a very acceptable smoke point of 22 mm.
After mixing the gas oil fractions from pipe 19 (with a cetane number of 20 which is Imacceptably low for diesel fuel) and from pipe 34 (with an ~ exceptionally high cetane number of 85), the result was a gas oil product in pipe 45 with an acceptable cetane number of 42.
The two gas fractions were mLxed and, flfter ~eparatioll of LPG
components, were used as fuel.
It can be seen from the Example that the entire relatively cheap vacuum residue i9 converted into valuable light products. Moreover, it appears that the mixing oE hydrocarbon distil1ateq with synthetlc hydrocarbon~ leads to products with good characteristic9.

.J

. , ' ' ,' . ' ' ., , ' '.
.
.

Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Process for the preparation of hydrocarbon mixtures from an oil residue, characterized in that a) the oil residue is separated into a low-asphaltene hydrocarbon fraction and a high-asphaltene hydrocarbon fraction;
b) the low-asphaltene hydrocarbon fraction is subjected to cracking, in which hydrocarbon distillates are formed;
c) the high-asphaltene hydrocarbon fraction is partially combusted with the aid of an oxygen-containing gas, a gas mixture containing carbon monoxide and hydrogen being formed;
d) at least a part of the gas mixture containing carbon monoxide and hydrogen is subjected to catalytic hydrocarbon synthesis, synthetic hydrocarbons being formed;
e) at least a part of the synthetic hydrocarbons are mixed with at least part of the hydrocarbon distillates from the cracking.

2. Process according to claim 1, characterized in that the oil residue is obtained by vacuum distillation of a residual fraction from atmospheric distillation of a crude oil.

3. Process according to claim 2, characterized in that the separation of the oll residue is carried out by solvent deasphalting.

4. Process according to of claim 3, characterized in that the oil residue before the separation into a low asphaltene fraction and a high-asphaltene fraction is subjected to a catalytic hydrogen treatment.

5. Process according to claims 3, characterized in that solvent deasphalting is carried out using n-butane as solvent at a pressure of 35-45 bar and a temperature of 100-150°C.

6. Process according to claim 1, characterized in that the cracking is catalytic cracking.

7. Process according to claim 6, characterized in that the catalytic cracking is carried out with a catalyst consisting of zeolite Y in a matrix of amorphous silica-alumina.

8. Process according to claim 6 or 7, characterized in that the catalytic cracking is carried out at a temperature of 400 to 550°C, a pressure of 1 to 10 bar and a space velocity of 0.25 to 5 kg.g-1.hour-1.

9. Process according to claim 1, characterized in that the high-asphaltene hydrocarbon fraction is partially combusted with the aid of oxygen in the presence of steam.

10. Process according to claim 9, characterized in that the partial combustion is carried out at a temperature of 1200-2000°C, a pressure of 10-70 bar and a resistence time of 1-10 sec.

11. Process accordlng to claims 1, characterized in that the hydrocarbon synthesis is carried out with a catalyst comprising cobalt and at least one of the metals: ruthenium, zirconium, titanium and chromium on silica, alumina or silica-alumina as carrier.

12. Process according to clalm 11, characterized in that the hydrocarbon synthesis is carried out at a temperature of 200-250°C, a pressure of 10-40 bar and a space velocity of 300-2000 N1.1.-1.hour-1.

13. Process according to claim 1, characterized in that the heavy fractions are removed from the products of the hydrocarbon synthesis and/or the cracking and that at least part of the heavy fractions is fed to the partial combustion step.

14. Process according to of claim 1, characterized in that at least part of the product of the hydrocarbon synthesis is subjected to a catalytic hydrogen treatment.