CA1117058A

CA1117058A - Process for the conversion of hydrocarbons

Info

Publication number: CA1117058A
Application number: CA000288341A
Authority: CA
Inventors: Frans Goudriaan
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1976-11-22
Filing date: 1977-10-07
Publication date: 1982-01-26
Also published as: JPS5364205A; GB1560148A; IT1088642B; DE2751863A1; NL7612960A; DE2751863C2; FR2371504A1; FR2371504B1; JPS618120B2

Abstract

A B S T R A C T
Process for the preparation of atmospheric hydrocarbon oil distillates.
An atmospheric residue is subjected to a catalytic hydrotreatment.
The hydrotreated product is separated by distillation into atmospheric distillates, a vacuum distillate and a vacuum residue. The vacuum residue is separated by deasphalting into a deasphalted oil and asphalt. The vacuum distillate and the deasphalted oil are converted by catalytic cracking and/or hydrocracking into atmospheric distillates. At least 50 %w of the asphalt is subjected to the catalytic hydrotreatment.

Description

1~17Q58 The invention relates to a process for the preparation of one or more atmospheric hydrocarbon oil distillates from an atmospheric hydro-carbon oil residue.
In the atmospheric distillation of crude mineral oil, as applied on a large scale in refineries for the preparation of atmospheric distillates, a residual oil is obtained as a by-product. In some cases this residual oil is suitable for use as the starting material in the preparation of lubricating oil, but generally the residual oil, which as a rule contains considerable quantities of sulphur, metals and asphaltenes, is only suitable for use as fuel oil.
In view of the increasing demand for atmospheric distillates, several processes were investigated in the past which were aimed at converting the residual oils into atmospheric distillates. Examples of such processes are catalytic cracking and hydrocracking. The use of the residual oils as such as the feed for these processes has considerable disadvantages which preclude their application on a commercial scale.
Thus, a major drawback of catalytic cracking of the residual oils is that because of the very high coke and gas production only a low yield of the desired atmospheric distillates is obtained. Hvdrocracking of the residual oils involves a very rapid catalyst deactivation and/or a very high gas production and/or a very high hydrogen consumption.
In view of the above and considering the f`act that in the atmospheric distillation of crude mineral oil about half of the crude oil is left behind as distillation residue, it will be clear that there is an urgent need for a process which offers the possibility of converting atmospheric hydrocarbon oil residues in an economically justifiable way into atmospheric hydrocarbon oil distillates such as gasolines.
Since catalytic cracking and hydrocracking have proved in practice to be excellent processes for the conversion of heavy hydrocarbon oil distillates such as vacuum gas oils into light distillates such as gasolines, the Applicant has carried out an investigation fo find out to what extent these processes can be employed in the conversion of the above-mentioned atmospheric residues. It has been found that ~117~58 by a proper combination of catalytic cracking and/or hydrocrack-ing as the main operation(s) with a catalytic hydrotreatment and a deasphalting as supplementary operations, a process can be realized that is highly suitable for this purpose. The present patent application relates to such a process.
Thus this invention provides a process or the prepara-tion of one or more hydrocarbon oil distillates by means of cat-alytic cracking or hydrocracking as the main operation in com-bination with catalytic hydrotreatment and deasphalting as supplementary operations starting from a hydrocarbon oil residue obtained by atmospheric distillation, which process comprises the steps of (a) subjecting the said atmospheric distillation residue to a catalytic hydrotreatment, (b) separating a hydrotreated product obtained in step (a) into one or more atmospheric distillates, a vacuum distillate and a vacuum residue by means of distillation, (c) separating the vacuum residue obtained in step (b) into a deasphalted oil and asphalt by means of deasphalting, (d) converting the vacuum distillate obtained in step (b) and the deasphalted oil obtained in step (c) by means of cata-lytic cracking or hydrocracking into one or more atmospheric distillates, and (e) subjecting at least 50% by weight of the asphalt obtained in step (c) to a catalytic hydrotreatment, said catalytic hydro-treatment being carried out under such conditions that more than 50~ by weight of the asphalt present in the feed for the catalytic hydrotreatment is converted into material that is not precipitated in a deasphalting step carried out under the same conditions as the deasphalting of the vacuum residue.
The process according to the invention comprises catalytic cracking and/or hydrocracking of a vacuum distillate . ~

,.

11~7~58 and a deasphalted oil as the main operation(s). In these opera-tions a considerable proportion of the feed concerned is con-verted into the said atmospheric distillates. One or more atmospheric distillates are separated as end products from the cracked product by distillation. To increase the yield of atmospheric distillates it is preferred to recycle at least part of the atmospheric residue obtained in the distillation of the cracked product to the catalytic cracker or hydrocracker. If the process according to the invention comprises catalytic crack-ing as one of the main operations and, in addition, at least partof the aforementioned atmospheric residue is recycled to the catalytic cracking unit and/or a deasphalted oil is used as the feed or as a feed component for the catalytic cracking unit, these liquids are preferably given a light catalytic hydrotreat-ment before they are subjected to catalytic cracking. In - 3a -, .

~17~58 the catalytic cracking process, which is preferably carried out in the presence of a zeolitic catalyst, coke is depcsited on the catalyst.
~his coke is removed from the catalyst by burning-off during a catalyst regeneration step that is combined with the catalytic cracking, whereby a waste gas is obtained which contains carbon monoxide and carbon dioxide. Catalytic cracking is preferably carried out at an average temperature of from 400 to 550C and in particular from 450 to 525C, a pressure of from 1 to 10 bar and in particular from 1.5 to 7.5 bar, a space velocity of from 0.25 to 4 kg.kg 1.h and in particular from 0.5 to 2.5 kg.kg .h and a rate of catalyst replenishment of from 0.1 to 5 and in particular from 0.2 to 2 tonnes of catalyst per 1000 tonnes of feed.
~he process according to the invention may comprise hydrocracking as one of the main operations. Hydrocracking is effected by contacting the feed at elevated temperature and pressure and in the presence of hydrogen with a suitable hydrocracking catalyst. Hydrocracking is preferably carried out as a two-stage process, in which the hydrocracking proper, which is effected in the second stage, is preceded by a catalytic hydro-treatment which serves mainly to reduce the nitrogen and polyaromatics contents of the feed to be hydrocracked. Catalysts suitable for use in the single stage hydrocracking process as well as in the second stage of the two-stage hydrocracking process are moderately and strongly acidic catalysts comprising one or more metals having hydrogenation activity on a carrier. Catalysts suitable for use in the first stage f the two-stage hydrocracking process are weakly and moderately acidic catalysts comprising one or more metals having hydrogenation activity on a carrier. Hydrocracking is preferably carried out at an average temperature of from 250 to 450C and in particular from 300 to 425C, a hydrogen partial pressure of from 25 to 300 bar and in particular from 50 to 150 bar, a space velocity of from 0.1 to 10 kg.l .h and in particular from 0.25 to 2 kg.l .h 1 and a hydrogen-to-feed ratio of from 200 to 3000 Nl.kg and in particular from 500 to 2000 Nl.kg . If the hydrocracking is carried out according to the two-stage process it is preferred to use the whole reaction product from the 1~17Q58 first stage (without ammonia, hydrogen sulphide or other volatile components being separated from it) as the feed for the second stage.
The process according to the invention comprises a supplementary operation in which deasphalting is applied to the vacuum residue of the hydrotreated product. The deasphalting is preferably carried out at elevated temperature and pressure and in the presence of an excess of a lower hydrocarbon such as propane, butane or pentane.
The process according to the invention comprises a further supple-mentary operation in which a catalytic hydrotreatment is applied to a mixture of an atmospheric residue and asphalt. This catalytic hydro-treatment has to be carried out under such conditions that more than 50 %w of the asphalt present in the feed for the catalytic hydrotreatment is converted into material which does not precipitate in a deasphalting step effected under the same conditions as the deasphalting of the vacuum residue. This catalytic hydrotreatment is preferably carried out as a two-stage process, in which the conversion proper of asphalt, which conversion is effected in the second stage, is preceded by a catalytic hydrotreatment intended mainly to reduce the metal content of the feed to be converted. Catalysts suitable for use in the one-stage catalytic hydrotreatment as well as in the second stage of the two-stage catalytic hydrotreatment comprise one or more metals having hydrogenation activity on a carrier, which carrier consists of more than 40 ~Ow alumina.
Catalysts suitable for use in the first stage of the two-stage catalytic hydrotreatment consist of more than 80 ~Ow silica. The catalytic hydro-treatment is preferably carried out at an average temperature of from ; 375 to 475C and in particular from 390 to 450C, a hydrogen partial pressure of from 25 to 300 bar and in particular from 50 to 200 bar, a space velocity of from 0.1 to 3.0 kg.l .h and in particular from 0.2 to 2.0 kg.l .h and a hydrogen-to-feed ratio of from 250 to 2500 Nl.kg 1 and in particular from 500 to 2000 Nl.kg . If the catalytic hydrotreatment is carried out in two stages, the first stage is preferably effected in the presence of a quantity of H2S corresponding to an H2S
content of the gas at the reactor inlet of more than 10 ~v and the second stage in the presence of a quantity of X2S corresponding to an H2S content of the gas at the reactor inlet of less than 5 ~Ov.

As stated hereinbefore, the catalytic hydrotreatment according to the invention has to be carried out under such conditions that more than 50 ~w of the asphalt present in the feed for the catalytic hydrotreatment is converted into products which do not precipitate in a deasphalting step effected under the same conditions as the deasphalting of the vacuum residue, Among these products are atmospheric distillates which are suitable as end products.
In the process according to the invention two streams are obtained which have to be subjected to catalytic cracking or hydrocracking, viz, a deasphalted oil and a vacuum distillate. For the conversion of the two streams preference is given to the same treatment and to treatment in one unit.
The process according to the invention is suitable both for the preparation of exclusively one or more light distillates as the end products and for the preparation of one or more light distillates together with one or more middle distillates as the end products. If the aim is to prepare exclusively one or more light distillates as the end products, a middle distillate to be separated from the cracked product and having an initial boiling point above the final boiling point of the heaviest light distillate desired is also eligible for repeated cracking, In that case, besides the vacuum distillate of the hydro-treated product, a middle distillate to be separated from the hydro-treated product and having an initial boiling point above the final boiling point of the heaviest light distillate desired is also eligible for use as feed component for the catalytic cracking or hydrocracking to be carried out as the main operation~
A process scheme for the conversion of atmospheric hydrocarbon oil residues into light and medium hydrocarbon oil distillates will be described hereinafter in more detail by reference to the a~pended figure.
Process scheme (see figure) The process is carried out in an apparatus comprising successively a catalytic hydrotreating section (1), the first atmospheric distillation section (2), a vacuum distillation section (3), a deasphalting section i~70~8 (4), a catalytic cracking section (5), and the second atmospheric distillation section (6). A hydrocarbon oil residue (7) obtained by atmospheric distillation is mixed with an asphalt (8) and the mixture, together with a hydrogen stream (9), is subjected to a catalytic hydro-treatment. After separation of a gas stream (10), substantially consisting of C4 hydrocarbons and H2S, from the hydrotreated product, the liquid reaction product ( 11 ) is separated by atmospheric distillation into a gasoline fraction (12), a middle distillate fraction (13) and a residue (14). The residue (14) is separated by vacuum distillation into a vacuum distillate (15) and a vacuum residue (16). The vacuum residue (16) is separated by deasphalting into a deasphalted oil (17) and an asphalt (18). The asphalt (18) is separated into t~ro portions (8) and (19) having the same composition. The vacuum distillate (15) is mixed with the deasphalted oil (17) and the mixture is catalytically cracked, In the regeneration of the catalyst in the catalytic cracking unit a waste gas (20) is obtained which contains carbon monoxide and carbon dioxide. The catalytically cracked product (21) is separated by atmospheric distillation into a C4 fraction (22), a gasoline fraction (23), a middle distillate fraction (24) and a residue (25) being a mixture of heavy cycle oil and slurry oil.
The present patent application also comprises an apparatus for carrying out the process according to the invention as schematically shown in the appended figure.
The process according to the invention was applied to an atmospheric distillation residue of a crude oil from the Middle East. The atmospheric distillation residue had an initial boi'ing point of 370C. By vacuum distillation of 100 pbw of the atmospheric residue, 44 pbw of a 520C
vacuum residue could be separated from it; by deasphalting these 44 pbw vacuurn residue at 145C and 41 bar with butane as the solvent and a solvent-to-oil weight ratio of 4:1, 21 pbw of C4 asphalt could be obtained from it. The process was carried out according to the appended process scheme. The following conditions were used in the various sections.
The catalytic cracking was effected in the presence of a zeolitic 1~17(~58 catalyst at a temperature of 490C, a pressure of 2.2 bar and a space velocity of 2 kg.kg .h The catalytic hydrotreatment was effected in two stages in the presence of an Ni/V/SiO2 catalyst comprising 0,5 pbw nickel and 2 pbw vanadium per 100 pbw silica in the first stage, and an Ni/Mo/Al203 catalyst comprising 4 pbw nickel and 11 pbw molybdenum per 100 pbw alumina in the second stage. The first stage of the catalytic hydro-treatment was conducted at an average temperature of 420C, a hydrogen partial pressure of 150 bar and a space velocity of 1.75 kg.1 .h and a hydrogen-to-feed ratio of 1000 Nl.kg 1. The second stage of the catalytic hydrotreatment was conducted at an average temperature of 425C, a hydrogen partial pressure of 150 bar, a space velocity of 1.9 kg.l .h and a hydrogen-to-feed ratio of 1500 Nl.kg The deasphalting was carried out at 145C and 41 bar with butane as the solvent and at a solvent-to-oil weight ratio of 4:1.
EXAMPLE
With 100 pbw of the 370C atmospheric distillation residue (7) as the starting material, the quantities of the various streams were as follows:
3.2 pbw hydrogen (9), 11.3 pbw C4 fraction + H2S (10), 102.6 pbw liquid product (11), 9.7 pbw C5-200C gasoline fraction (12), 18.2 pbw 200-370C middle distillate fraction (13), 74.7 pbw 370C residue (14), 39.4 pbw 370-520C vacuum distillate (15), 35.3 pbw 520C vacuum residue (16), 23.8 pbw deasphalted oil (17), 11.5 pbw asphalt (18), 10.7 pbw portion (8), o.8 pbw portion (19), 9.7 pbw C4 fraction (22), 30.2 pbw C5-200C gasoline fraction (23), 10.1 pbw 200-370C middle distil]ate fraction (24), and 9.4 pbw 370C residue (25).

Claims

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

1. A process for the preparation of one or more hydro-carbon oil distillates by means of catalytic cracking or hydro-cracking as the main operation in combination with catalytic hydro-treatment and deasphalting as supplementary operations starting from a hydrocarbon oil residue obtained by atmospheric distillation, which process comprises the steps of (a) subjecting the said atmospheric distillation residue to a catalytic hydrotreatment, (b) separating a hydrotreated product obtained in step (a) into one or more atmospheric distillates, a vacuum distillate and a vacuum residue by means of distillation, (c) separating the vacuum residue obtained in step (b) into a deasphalted oil and asphalt by means of deasphalting, (d) converting the vacuum distillate obtained in step (b) and the deasphalted oil obtained in step (c) by means of cata-lytic cracking or hydrocracking into one or more atmospheric distillates, and (e) subjecting at least 50% by weight of the asphalt obtained in step (c) to a catalytic hydrotreatment, said catalytic hydro-treatment being carried out under such conditions that more than 50% by weight of the asphalt present in the feed for the catalytic hydrotreatment is converted into material that is not precipitated in a deasphalting step carried out under the same conditions as the deasphalting of the vacuum residue.

2. A process according to claim 1, characterized in that at least part of a residue obtained in an atmospheric distilla-tion of a catalytically cracked or hydrocracked product obtained in step (d) is recycled to the catalytic cracking or hydrocrack-ing operation concerned.

3. A process according to claim 2, characterized in that, the deasphalted oil and the recycled part of the residue of the catalytically cracked product are given a light catalytic hydro-treatment before the said deasphalted oil and the said recycled part of the residue are subjected to catalytic cracking, said catalytic cracking being the main operation.

4. A process according to claim 1, characterized in that catalytic cracking is carried out at an average temperature of from 400 to 550°C, a pressure of from 1 to 10 bar, a space velocity of from 0.25 to 4 kg.kg-1.h-1 and a rate of catalyst replenishment of from 0.1 to 5 tonnes of catalyst per 1000 tonnes of feed.

5. A process according to claim 1 characterized in that hydrocracking is carried out as a two-stage process in the pre-sence of a weakly or moderately acidic catalyst comprising one or more metals having hydrogenation activity on a carrier in the first stage and a moderately or strongly acidic catalyst compris-ing one or more metals having hydrogenation activity on a carrier in the second stage.

6. A process according to claim 1 characterized in that hydrocracking is carried out as a two-stage process and that the whole reaction product from the first stage is used as the feed for the second stage.

7. A process according to claim 1 characterized in that hydrocracking is carried out at an average temperature of from 250 to 450°C, a hydrogen partial pressure of from 25 to 300 bar, a space velocity of from 0.1 to 10 kg.1-1.h-1 and a hydrogen-to-feed ratio of from 200 to 3000 N1.kg-1.

8. A process according to claim 1 characterized in that the catalytic hydrotreatment is carried out as a two-stage pro-cess in the presence of a catalyst consisting of more than 80 %
w silica in the first stage and a catalyst comprising one or more metals having hydrogenation activity on a carrier, which carrier consists of more than 40%w alumina, in the second stage.

9. A process according to claim 1 or 8, characterized in that the catalytic hydrotreatment is carried out at an average temperature of from 375 to 475°C, a hydrogen partial pressure of from 25 to 300 bar, a space velocity of from 0.1 to 3.0 kg.1-1 .h-1 and a hydrogen-to-feed ratio of from 250 to 2500 N1.kg-1.

10. A process according to claim 1, characterized in that the catalytic hydrotreatment is carried out as a two-stage process and that the first stage is effected in the presence of a quantity of H2S corresponding to an H2S content of the gas at the reactor outlet of more than 10 %v and the second stage in the presence of a quantity of H2S corresponding to an H2S content of the gas at the reactor inlet of less than 5 %v.

11. A process according to claim 1, characterized in that both the conversion of the deasphalted oil and the conversion of the vacuum distillate are carried out in the same way, i.e.
by either catalytic cracking or hydrocracking, and that these conversions are effected in one unit.