Title:
Production of lubricating oils
United States Patent 3902988
Abstract:
A range of lubricating oils is produced by splitting a petroleum fraction boiling above 350°C into light and heavy fractions, preferably at a cut point of 400°-500°C treating the light fraction or fractions by catalytic dewaxing and solvent extraction and treating the heavy fraction or fractions by catalytic hydrogenation and solvent dewaxing. Part of the heavy fraction may be solvent extracted and solvent dewaxed, and part solvent dewaxed only. The catalytic dewaxing process uses a mordenite catalyst and the catalytic hydrogenation may produce either high or super-high oils.
US Patent References:
Process for preparing a multi-grade lubricating oil and product
Beuther et al. - November 1960 - 2960458
CATALYTIC CONVERSION OF HYDROCARBONS
Lawrance et al. - June 1970 - 3516925
/3652448.html
Cummins - March 1972 - 3652448
/3732156.html
Bennett et al. - May 1973 - 3732156
LUBE OILS BY SOLVENT DEWAXING AND HYDRODEWAXING WITH A ZSM-5 CATALYST
Chen - August 1973 - 3755138
Process for preparing a multi-grade lubricating oil and product
Beuther et al. - November 1960 - 2960458
CATALYTIC CONVERSION OF HYDROCARBONS
Lawrance et al. - June 1970 - 3516925
/3652448.html
Cummins - March 1972 - 3652448
/3732156.html
Bennett et al. - May 1973 - 3732156
LUBE OILS BY SOLVENT DEWAXING AND HYDRODEWAXING WITH A ZSM-5 CATALYST
Chen - August 1973 - 3755138
Inventors:
Bennett, Robert Neil (Englefield Green, EN)
Gray, Colin Leslie (Fleet, EN)
Gray, Colin Leslie (Fleet, EN)
Application Number:
05/436162
Publication Date:
09/02/1975
Filing Date:
01/24/1974
View Patent Images:
Export Citation:
Assignee:
The British Petroleum Company Limited (London, EN)
Primary Class:
Other Classes:
208/18, 208/111.300, 208/92, 208/111.350, 208/112
International Classes:
C10G67/00; C10G37/04; C10G41/00; C10G13/02
Field of Search:
208/80,111
US Patent References:
Primary Examiner:
Gantz, Delbert E.
Assistant Examiner:
Schmitkons G. E.
Attorney, Agent or Firm:
Morgan, Finnegan, Pine, Foley & Lee
Claims:
We claim
1. A process for the production of a range of lubricating oils comprising separating a petroleum fraction boiling above 350°C. into at least one lighter fraction and at least one heavier fraction, subjecting at least a portion of the lighter fraction to a hydro-catalytic dewaxing process and a solvent extraction process, said hydro-catalytic dewaxing process comprising passing the lighter fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table incorporated with a crystalline mordenite or reduced alkali metal content together with hydrogen at a temperature of from 250°-500°C. and a pressure of from 7 to 200 bars gauge and, subjecting at least a portion of a heavier fraction to a hydro-catalytic viscosity index improvement process and a solvent dewaxing process, said hydro-catalytic viscosity index improvement process comprising passing the heavier fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table on a refractory oxide support together with hydrogen at a temperature of from 340°-460°C. and a pressure of from 70-210 bars gauge.
2. A process as claimed in claim 1 wherein the cut point between the lighter and heavier fractions is in the range 450°-500°C.
3. A process as claimed in claim 1 for the production of a range of lubricating oils comprising separating a petroleum fraction boiling above 350°C into at least one lighter fraction and at least two heavier fractions, subjecting the lighter fraction or fractions to said hydrocatalytic dewaxing process and a solvent extraction process for the removal of aromatics, subjecting at least one of the heavier fractions to said hydrocatalytic viscosity index improvement process and a solvent dewaxing process and subjecting at least one other of the heavier fractions to a solvent extraction process for the removal of aromatics and a solvent dewaxing process.
4. A process as claimed in claim 3 wherein the feedstock is separated into three or more heavier fractions, at least one of which is subjected to said hydrocatalytic viscosity index improvement process and a solvent dewaxing process, at least another one of which is subjected to a solvent extraction process for the removal of aromatics and a solvent dewaxing process, and at least another one of which is subjected to a solvent dewaxing process without either a hydrocatalytic viscosity index improvement process or a solvent extraction process for the removal of aromatics.
5. A process as claimed in claim 1 wherein the solvent extraction uses furfural at a solvent:oil ratio of 0.5 to 5:1 by volume and an average temperature of from 15° to 150°C.
6. A process as claimed in claim 1 wherein the hydrocatalytic dewaxing process conditions are a temperature of from 265° to 430°C, a pressure of from 40 to 200 bars gauge, a space velocity of from 0.5 to 10 v/v/hr and a hydrogen gas rate of from 900 to 2,700 m3 /m3.
7. A process as claimed in claim 1 wherein the hydrocatalytic viscosity index improvement process conditions are a temperature of from 340° to 430°C, a pressure of from 70 to 170 bars gauge, a space velocity of from 0.5 to 2 v/v/hr and a hydrogen gas rate of 360 to 1,800 m3 /m3 to give a dewaxed product viscosity index of from 75 to 100.
8. A process as claimed in claim 1 wherein the hydrocatalytic viscosity index improvement process conditions are a temperature of from 380° to 460°C a pressure of from 120 to 210 bars gauge, a space velocity of from 0.2 to 2 v/v/hr and a hydrogen gas rate of from 360 to 1,800 m3 /m3 to give a dewaxed product viscosity index of greater than 100.
9. A process as claimed in claim 1 wherein the solvent dewaxing uses an alkyl ketone at a solvent:oil ratio of 0.5 to 10:1 and a temperature of from -5° to -30°C.
1. A process for the production of a range of lubricating oils comprising separating a petroleum fraction boiling above 350°C. into at least one lighter fraction and at least one heavier fraction, subjecting at least a portion of the lighter fraction to a hydro-catalytic dewaxing process and a solvent extraction process, said hydro-catalytic dewaxing process comprising passing the lighter fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table incorporated with a crystalline mordenite or reduced alkali metal content together with hydrogen at a temperature of from 250°-500°C. and a pressure of from 7 to 200 bars gauge and, subjecting at least a portion of a heavier fraction to a hydro-catalytic viscosity index improvement process and a solvent dewaxing process, said hydro-catalytic viscosity index improvement process comprising passing the heavier fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table on a refractory oxide support together with hydrogen at a temperature of from 340°-460°C. and a pressure of from 70-210 bars gauge.
2. A process as claimed in claim 1 wherein the cut point between the lighter and heavier fractions is in the range 450°-500°C.
3. A process as claimed in claim 1 for the production of a range of lubricating oils comprising separating a petroleum fraction boiling above 350°C into at least one lighter fraction and at least two heavier fractions, subjecting the lighter fraction or fractions to said hydrocatalytic dewaxing process and a solvent extraction process for the removal of aromatics, subjecting at least one of the heavier fractions to said hydrocatalytic viscosity index improvement process and a solvent dewaxing process and subjecting at least one other of the heavier fractions to a solvent extraction process for the removal of aromatics and a solvent dewaxing process.
4. A process as claimed in claim 3 wherein the feedstock is separated into three or more heavier fractions, at least one of which is subjected to said hydrocatalytic viscosity index improvement process and a solvent dewaxing process, at least another one of which is subjected to a solvent extraction process for the removal of aromatics and a solvent dewaxing process, and at least another one of which is subjected to a solvent dewaxing process without either a hydrocatalytic viscosity index improvement process or a solvent extraction process for the removal of aromatics.
5. A process as claimed in claim 1 wherein the solvent extraction uses furfural at a solvent:oil ratio of 0.5 to 5:1 by volume and an average temperature of from 15° to 150°C.
6. A process as claimed in claim 1 wherein the hydrocatalytic dewaxing process conditions are a temperature of from 265° to 430°C, a pressure of from 40 to 200 bars gauge, a space velocity of from 0.5 to 10 v/v/hr and a hydrogen gas rate of from 900 to 2,700 m3 /m3.
7. A process as claimed in claim 1 wherein the hydrocatalytic viscosity index improvement process conditions are a temperature of from 340° to 430°C, a pressure of from 70 to 170 bars gauge, a space velocity of from 0.5 to 2 v/v/hr and a hydrogen gas rate of 360 to 1,800 m3 /m3 to give a dewaxed product viscosity index of from 75 to 100.
8. A process as claimed in claim 1 wherein the hydrocatalytic viscosity index improvement process conditions are a temperature of from 380° to 460°C a pressure of from 120 to 210 bars gauge, a space velocity of from 0.2 to 2 v/v/hr and a hydrogen gas rate of from 360 to 1,800 m3 /m3 to give a dewaxed product viscosity index of greater than 100.
9. A process as claimed in claim 1 wherein the solvent dewaxing uses an alkyl ketone at a solvent:oil ratio of 0.5 to 10:1 and a temperature of from -5° to -30°C.
Description:
This invention relates to the production of lubricating oils, and particularly to the production of a wide range of such oils.
The main steps in the production of lubricating oils from petroleum fractions are (a) aromatics removal giving an improved viscosity index and (b) dewaxing giving an improved pour point. Both steps normally use solvents to obtain the desired results, but hydro-catalytic alternatives have also been proposed for both steps. Each of the four processes has its advantages and disadvantages. In the present invention the four processes are combined in a particular way to make the best use of the potential of each process and to avoid using processes for duties for which they are not suited.
According to the present invention, a process for the production of a range of lubricating oils comprises separating a petroleum fraction boiling above 350°C into at least one lighter fraction and at least one heavier fraction, subjecting some or all of the lighter fraction or fractions to a hydro-catalytic dewaxing process and a solvent extraction process for the removal of aromatics and subjecting some or all of the heavier fraction or fractions to a hydrocatalytic viscosity index improvement process and a solvent dewaxing process.
The term "lubricating oil" as used in this specification includes lubricating oils for any use and also speciality oils boiling within the lubricating oil boiling range, e.g., transformer oils. A particular feature of the present invention is that it allows the production of a wide range of oils from light spindle oils to heavy automative oils derived from bright stocks.
Preferably the cut point between the lighter and heavier fraction or fractions is in the range 450° to 500°C.
The number of products obtained from the lighter fraction may conveniently be from 2 to 4, for example spindle oils and the two lightest grades of automotive lubricating oils.
The lighter fraction or fractions are treated, as indicated above, by the combination of hydrocatalytic dewaxing and solvent extraction to remove aromatics. The processes may be used in either order, but, preferably, the hydro-catalytic dewaxing is first. The sequence may treat a single wider boiling range fraction with subsequent distillation to give the required products, or may treat a series of fractions in blocked operation, the latter being preferred.
The preferred hydro-catalytic dewaxing process comprises passing the lighter fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table incorporated with a crystalline mordenite of reduced alkali metal content together with hydrogen at a temperature of from 250° - 500°C and a pressure of from 7 to 200 bars gauge. It may follow the general procedure described and claimed in our UK Pat. Nos. 1088933 and 1134014.
A particular feature and advantage of hydro-catalytic dewaxing is its ability of the process to dewax to low pour points of from -50° to -18°C with the present lighter fractions, which normally have pour points of from 20° to 45°C. Such low pour points cannot be obtained by solvent dewaxing except at exorbitant cost and such low pour points have hitherto been obtained by urea dewaxing, itself a relatively expensive process.
The wax in these lighter fractions is crystalline or paraffinic wax, e.g., n-paraffins or slightly branched paraffins and it is selectively cracked to lower boiling paraffins, particularly C 3 and C 4 paraffins. The selective breakdown of the paraffin wax hydrocarbons is due to the nature of the mordenite based catalyst which promotes the selective attack of these hydrocarbons but not of the other hydrocarbons present in the feedstock.
Suitable process conditions for the catalytic dewaxing include, besides a temperature within the range 250° - 500°C and a pressure within the range 7 - 200 bars gauge as indicated above, a space velocity between 0.1 - 20.0 v/v/hr, and a gas rate of 90 - 3,600 m 3 /m 3 of hydrogen.
Preferred catalytic dewaxing conditions are: Temperature °C 265 - 430 Space velocity v/v/hr 0.5 - 10.0 Pressure bars gauge 40 - 200 Hydrogen gas rate m 3 /m 3 900 - 2700
The term "crystalline mordenite of reduced alkali metal content" means, preferably, a mordenite with an alkali metal content of less than 3% wt. The deficiency of alkali metal cations can be made up with other metal cations for example Group II metal cations, particularly magnesium or rare earth metal cations. Preferably however the mordenite is a "decationised mordenite" which means a mordenite having a deficiency of metal cations. As alternative term in the art is hydrogen mordenite, since it is assumed that when metal cations are removed they are replaced by hydrogen ions. However, since it is not possible to detect the presence of hydrogen ions in zeolites, the precise structure remains in doubt. A cation deficiency can, on the other hand, be readily measured by analysis of the metallic elements present in the zeolite.
Natural or freshly prepared synthetic mordenite has the formula: ##EQU1## where Me is a metal cation, n is the valency of the cation and X is variable between nil and 7 depending on the thermal history of the sample. Me is commonly sodium and in one common form of decationisation sodium mordenite is base exchanged with ammonium cations. The ammonium form is then heated to drive off ammonia, leaving behind the hydrogen form or decationised mordenite. According to the second method the mordenite may be treated with a mineral acid, for example hydrochloric or sulphuric acid, in order directly to decationise the mordenite. A combination of acid treatment and ammonium treatment can also be used.
Preferably the decationised mordenite used in the present invention has a higher than normal silica:alumina ratio of at least 14:1. In specific examples ratios of as high as 90:1 have been obtained and a practical upper limit may thus be 100:1. Particularly preferred silica-alumina ratios are in the range 14:1 to 50:1.
It has been found that certain decationisation treatments remove aluminium as well as the expected metal cations and desirably therefore the mordenite used in the present invention having a higher than normal silica:alumina ratio is obtained by treatment of a metal cation-containing mordenite, particularly sodium mordenite, with a strong acid, for example sulphuric or hydrochloric acid, of from 5 - 50% wt strength and preferably from 10 to 20% wt strength. A single treatment or two or more successive treatments may be given with acids of the strengths stated above.
A convenient method of treatment is to treat the mordenite with acid under reflux for a period of 2 - 12 hours.
In the decationised mordenite the residual metal cation content, for example the sodium cation content, should be less than 3% wt of the mordenite and preferably less than 1.5% wt of the mordenite.
It should be emphasised that mordenites with higher than normal silica/alumina ratios retain the crystal structure of mordenite and are not significantly altered in terms of physical strength, stability or crystallinity.
The hydrogenating component is preferably a platinum group metal, particularly platinum or palladium, and it is preferably added by ion-exchange. The amount of the platinum group metal is preferably within the range 0.01 to 10% wt., particularly 0.1 to 5% wt. However, iron group metals, particularly nickel, also give useful results and they may be used in amounts similar to the platinum group metals. Mixtures of certain Group VI and VIII metals and compounds may also be used, e.g. cobalt and molybdenum.
The catalyst is preferably calcined at for example 250° - 600°C before use to remove any water and to eliminate any ligands attached to the hydrogenation component.
The product from the dewaxing may be distilled to remove light ends boiling below the boiling point of the feedstock, these being, as previously indicated, mostly C 3 and C 4 paraffins which are useful as petrochemical feedstocks or LPG.
The product from the dewaxing is then treated with a selective solvent to remove aromatics. The dewaxing reduces the viscosity index, and irrespective of whether the dewaxing precedes the solvent extraction or not, some VI improvement will usually be necessary to restore at least a part of this VI loss and sometimes to increase it above its original level. With the lighter fractions being treated the product VI's required will normally be within the range 0 to 100, and solvent extraction can produce such VI's efficiency and economically from such feedstocks.
The solvent may be sulphur dioxide/benzene, phenol, glycol, or, preferably, furfural and it may be used in a fixed or rotating disc contactor with from 1 to 20 theoretical extraction stages. The main process variables are solvent:oil ratio, which may be from 0.5 to 5:1 by volume, particularly 1.5 to 4.0:1, average temperature, which may be from 15° to 150°C, particularly 30° - 130°C, and temperature gradient in the column which may be
Column top temperature 150°C maximum Column base 38 - 121°C
Conventional steps of separation of the extract and raffinate and recovery and recycle of solvent may be employed.
The heavier fraction or fractions boiling above the cut point may contain residue possibly together with one or more heavier distillates. This portion of the original feedstock is, as previously indicated, treated by the combination of hydro-catalytic viscosity index improvement and solvent dewaxing. The steps may be used in either order, with, preferably, the viscosity index improvement step first. The feedstock may be treated in bulk with subsequent distillation into product fractions or, preferably, separated first into fractions which are passed through the treatment stages in blocked operation. Preferably it is separated into at least two fractions, one being a vacuum distillate and the other a vacuum residue, parts of which may, if desired, be subsequently reblended.
The vacuum residue portion will contain asphaltenes and possibly organo-metallic compounds, and may, therefore, be de-asphalted prior to the hydro-catalytic treatment step. The de-asphalting solvent may be a low-boiling n-paraffin, particularly propane, which may be used at 20° - 100°C, preferably 40° - 80°C, 5 - 50 bars gauge, preferably 25 - 35 bars gauge, and solvent ratios by volume of 1 - 20:1 preferably 5 - 13:1.
The preferred hydrocatalytic viscosity index improvement step comprises passing the heavier fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table on a refractory oxide support together with hydrogen at a temperature of from 340° - 460°C and a pressure of from 70 - 210 bars gauge.
The hydro-catalytic viscosity index improvement step may be used to give products with moderate viscosity index, e.g., 75 - 100 or high viscosity index, e.g., 101 - 150 and a particular advantage of its use is this flexibility. High VI oils are particularly useful not only for certain specialised uses but also in reducing or eliminating the need for viscosity index improvers in multigrade oils, and solvent extractions cannot easily or economically produce such high VI oils.
Thus within the context of hydrocatalytic treatment for VI improvement, two general processes are recognised. These are (i) a relatively mild treatment to give a moderate VI improvement, e.g., 75 to 100 VI after dewaxing with minimum breakdown and decrease in viscosity. Increase in VI of the product to bring it up to multigrade oil requirements, if desired, can be achieved by the use of known polymeric VI improvers (ii) a more severe treatment with extensive breakdown and decrease in viscosity but giving a larger VI improvement, e.g., greater than 100 VI after dewaxing. A larger amount of lower boiling gas oil, kerosene and gasoline byproducts is obtained with the more severe treatment.
The broad ranges of process conditions and the preferred ranges for the two types of process may be chosen from
Milder type More severe Broad range (i) process type (ii) process ______________________________________ Temperature 340 - 460 340 - 430 380 - 460 Pressure bars gauge 70 - 210 70 - 170 120 - 210 Space velocity v/v/hr 0.1 - 5 0.5 - 2 0.2 - 2 Hydrogen gas rate m 3 /m 3 360 - 1800 360 - 1800 360 - 1800 ______________________________________
The refractory inorganic oxide support may be one or more oxides of elements of Groups II, III or IV of the Periodic Table, and may contain halogen. Preferably the amounts of the components of the support are chosen from the following ranges:
Al 2 O 3 10 - 100% wt SiO 2 0 - 90 % wt B 2 O 3 0 - 25 % wt F or Cl 0 - 15 % wt
The hydrogenating component is preferably one or more of the oxides or sulphides of the Group VIa metals (i.e., chromium, molybdenum or tungsten) and the iron group metals (i.e., iron, cobalt or nickel). If platinum group metals are used they are desirably in metallic form.
The amounts of the hydrogenating components may be
Group VIa metals 2 - 25% wt (Expressed as metal) Iron group metals 1 - 15% wt " Platinum group metals 0.1 - 5% wt "
Preferred hydrogenating components are from 2 - 25% wt of molybdenum (expressed as metal but present as oxide or sulphide) and 1 - 15% wt of nickel and/or cobalt (again expressed as metal but present as oxide or sulphide).
For the type (i) process the preferred support has from 50 - 90% wt of Al 2 O 3 and 10 - 50% wt of SiO 2 . The type (ii) process preferably uses the same support, the increased severity being obtained from more severe operating conditions, but, if desired, a more acidic support may be used for example one with 60 - 90% wt SiO 2 and 10 - 40% wt Al 2 O 3 or 85 - 95% wt Al 2 O 3 and 5 - 15% wt F or Cl.
The precise choice and number of heavier fractions treated will depend on the VI improvement required. The greater the VI improvement the greater the drop viscosity and, preferably, at least a proportion of vacuum residue is used with the type (ii) process. Vacuum distillate and/or residue fractions may be used with the type (i) process.
The term viscosity index as used in this specification means that measured by ASTM D2270/64.
In addition to some breakdown to products boiling below 350°C there may be conversion of sulphur and nitrogen compounds to H 2 S and NH 3 . At least the latter is desirably removed, by scrubbing with water, from any gas recycled and products boiling below 350°C are desirably removed by distillation.
The product from the hydrocatalytic viscosity index improvement step is then solvent dewaxed. The heavier product fractions are normally required to have pour points of from -18° to -9°C which can be efficiently and economically produced with solvents. Solvent dewaxing also removes the microcrystalline wax present in these heavier fractions more readily than does catalytic dewaxing.
The solvent may be an alkyl ketone, the alkyl groups being the same or different and having 1 - 4 carbon atoms. Preferred solvents are methyl ethyl ketone, methyl isobutyl ketone or mixtures of the same. An aromatic, e.g., benzene or toluene may also be present, preferably in an amount of from 25 - 75% wt vol of the total solvent. Other suitable solvents are C 1 - C 4 chlorinated hydrocarbons, e.g., methylene chloride or ethylene dichloride or C 2 - C 6 alkanes, particularly propane.
The oil is mixed with solvent and is usually heated to enusre complete solution and is then chilled to precipitate the wax. Solvent:oil ratios may be from 0.5 to 10:1 by volume, preferably 1 to 5:1 and the mixture may be chilled to from -5° to -30°C. The chilling rate may be from 0.5° to 10°C/minute, preferably 2° to 7°C/minute.
The precipitated wax is removed by filtration and the filter cake is washed with cool solvent usually in a solvent/oil ratio of 0.2:1 - 8:1. The dewaxed oil is freed from solvent by distillation the solvent being recycled for re-use. Similarly the precipitated wax and the wash solvent may be separated into product and solvent fractions by distillation.
While the invention, in its broadest aspect, splits the feedstock into two main streams, further sub-division is possible with a third stream taking a wholly solvent route, a fourth stream being subjected only to solvent dewaxing and possibly a fifth stream taking a wholly catalytic route.
The present invention, therefore, includes a process for the production of a range of lubricating oils comprising separating a petroleum fraction boiling above 350°C into at least one lighter fraction and at least two heavier fractions, subjecting the lighter fraction or fractions to a hydrocatalytic dewaxing process and a solvent extraction process for the removal of aromatics, subjecting at least one of the heavier fractions to a hydrocatalytic viscosity index improvement process and a solvent dewaxing process and subjecting at least one other of the heavier fractions to a solvent extraction process for the removal of aromatics and a solvent dewaxing process.
Such a three-stream process is particularly suitable when it is desired to produce both 75 - 100 VI and 101 - 150 VI products from the heavier fractions, the former being produced from the wholly solvent stream and the latter from the mixed catalytic and solvent route.
In a further embodiment the feedstock may be separated into three or more heavier fractions, at least one of which is subjected to a hydrocatalytic viscosity index improvement process and a solvent dewaxing process, at least another one of which is subjected to a solvent extraction process for the removal of aromatics and a solvent dewaxing process, and at least another one of which is subjected to a solvent dewaxing process without either a hydrocatalytic viscosity index improvement process or a solvent extraction process for the removal of aromatics.
All or any of the product fractions may be finished in known manner to improve colour, oxidation stability or light stability. Thus they may be treated with clay or bauxite, or, preferably, given a mild hydrocatalytic treatment known as hydrofinishing. Such finishing treatments may be less necessary with the lighter catalytically dewaxed fractions.
The present invention may be used with a new lubricating oil plant or can be used to expand an existing plant formed of solvent extraction and solvent dewaxing units. It has been found that the addition of two catalytic units to an existing plant of two solvent units gives a reduction of up to 10% in capital cost as compared with adding two further solvent units or one further solvent unit and one catalytic unit. This advantage is in addition to the other advantages of flexibility, usage of individual processes in the most efficient manner and the ability to produce from a single plant, oils ranging from light oils with a viscosity of 22 cSt at 100°F (38°C) and a pour point of -40°C to heavy oils with a viscosity of 1,200 cSt at 100°F (38°C) and a pour point of -12°C.
The invention is illustrated with reference to the accompanying drawing which is a flow diagram of a lubricating oil production process according to the present invention. The drawing is based on the expansion of an existing lubricating oil unit with existing plant indicated by shading.
In the drawing, the plant consists of two vacuum distillation columns 1, 2, two propane deasphalting units 3, 4, a catalytic dewaxing unit 5, a catalytic hydrogenating unit 6, a furfural extraction unit 7 and a solvent dewaxing unit 8.
Atmospheric residue with an initial boiling point of 250°C is fed through lines 9, 10 to the vacuum distillation columns 1, 2. Each column separates the atmospheric residue into light ends boiling below 350°C which are taken off overhead through lines 11, 12 for disposal elsewhere, 4 distillate fractions A, B, C, D, and A 1 , B 1 , C 1 , D 1 and a residue fraction E and E 1 . Distillates A, B, C are passed through lines 13, 14, 15 to the catalytic dewaxing unit 5. All or part of distillates A 1 , B 1 and C 1 can also be passed, if desired, to the catalytic dewaxing unit 5 through lines not shown. The catalytically dewaxed distillates then pass to the furfural extraction unit 7 and are recovered as A 2 , B 2 and C 2 products through lines 16, 17 and 18. Before the furfural extraction unit, the distillate C stream is split, part of it, going separately through the furfural extraction unit at different extraction conditions and then, via line 19, for blending with a stream described hereafter.
Distillate D goes via line 20 (together with distillate D 1 if desired) to the catalytic hydrogenation unit 6 and then to the solvent dewaxing unit 8 being recovered as product D 2 through line 21 after blending with a portion of distillate C from line 19 and a portion of residue E 1 from line 30. Residue E passes through line 22 to the propane deasphalting unit 3 and is then split into three. Part goes through line 23 to the catalytic hydrogenation unit 6, part goes through line 24 to the furfural extraction unit 7 and part by-passes both units, going direct to the solvent dewaxing unit 8 through line 25. The part going through line 23 is blended with distillate D from line 20 and thus eventually becomes part of product D 2 . The part going via line 24 through the furfural extraction unit then passes to the solvent dewaxing unit emerging through line 26 as product E 3 . The part going through line 25 direct to the solvent dewaxing unit emerges as product E 4 through line 27.
Residue E 1 is sent via line 28 to the propane deasphalting unit 4, the catalytic hydrogenation unit 6, and the solvent dewaxing unit 8 emerging through line 29 as product E 2 . Part of this product, as indicated above, is blended with product D 2 through line 30.
The invention is illustrated by the following example.
Example
A range of lubricating oils was produced from an atmospheric residue of a Kuwait crude oil using the process scheme described above. The grades produced and the feedstocks used are shown in Table 1 below.
Table 1 ______________________________________ Grade Feedstock ______________________________________ Transformer oil Vacuum Gas Oil 20S A cut 33/100 B cut 110/75 C cut 22/125 C cut 110/95 50% DAO, 50% D cut 550/95 DAO 750/85 DAO ______________________________________
In the grades, 20 S was a spindle oil of 4.1 cSt at 210°F.
In the other grades the first figure refers to the viscosity in cSt measured at 100°F and the second figure to the viscosity index.
The feedstocks were produced by vacuum distillation of the atmospheric residue. The vacuum gas oil cut was collected overhead and had a boiling range of 210°-410°C and a viscosity of 2.0 cSt at 210°F. The A, B, C and D cuts were side streams having the following characteristics.
______________________________________ TBP Cut Boiling Range Viscosity (determined by GLC) cSt at 210°F) ______________________________________ A 330 - 460 3.9 B 360 - 495 6.1 C 350 - 580 9.4 D -- 14.4 ______________________________________
Where blends of cuts were used, the percentages were by volume. The residue was deasphalted using propane as solvent to give deasphalted oil (DAO) having a viscosity of 36.5 cSt at 210°F.
The first four grades were produced from the indicated feedstocks by a combination of catalytic dewaxing and furfural extraction.
The catalytic dewaxing conditions were
Temperature °C 320-400°C Pressure bars gauge 69 Gas recycle rate m 3 /m 3 1684 LHSV v/v/hr 1.0 Catalyst 0.5% wt. platinum on mordenite decationised to a Na content of 0.75% wt. and acid treated to a silica:alumina ratio of 18:1.
The recycle gas was scrubbed to reduce the H 2 S content to a maximum of 500 ppm vol. of H 2 S at the reactor outlet and the NH 3 content to less than 5 ppm vol.
The yields from the catalytic dewaxing and the furfural treatment, and the amount of furfural used are shown in Table 2.
TABLE 2 ____________________________________________________________ ______________ Catalytic Dewaxing Furfural Extraction ____________________________________________________________ ______________ Dewaxed Chemical Gas Gasoline Furfural Extraction Grade Lube Hydrogen Yield Yield Treatment Yield Yield Consumption % wt. % wt. % vol. % wt. % wt. scf/brl. C 1 -C 5 C 5 -117°C ____________________________________________________________ ______________ Transformer Oil 70 300 26.0 4.0 100 55 20S 82 200 14.0 4.0 80 75 33/100 82.5 280 12.5 5.0 400 48 110/75 80 400 16.0 4.0 200 68 ____________________________________________________________ ______________
The remaining four grades were produced from the indicated feedstocks by a combination of hydrogenation and solvent dewaxing.
The hydrogenation conditions were
22/125 Other Grade Grades ______________________________________ Temperature °C 400-420 350-420 Pressure bars gauge 138 138 Gas recycle rate m 3 /m 3 1684 1250 LHSV v/v/hr 0.5 1.0 Catalyst 1.75% wt Co and 12.7% wt Mo on silica alumina, having a silicon content of 9% wt. by weight of the support. ______________________________________
The solvent dewaxing conditions were
Temperature °C -12 to -18 Solvent/oil ratio 6:1 to 12:1 Solvent Methyl Isobutyl Ketone
The yields from the processes are shown in Table 3.
TABLE 3 ____________________________________________________________ ______________ Hydrogenation Data Dewaxing Data ____________________________________________________________ ______________ Waxy Chemical Gas Gasoline Middle Product Grade Lube Hydrogen Yield Yield Distillate Yield Yield Consumption % wt. % wt. Yield % wt. % wt. scf/brl C 5 -177°C % wt. 177-371°C ____________________________________________________________ ______________ 110/95 81.0 720 5.3 4.8 12.5 83.5 550/95 90.7 500 3.1 0.3 6.8 83.5 750/85 96.0 330 1.2 0.4 2.5 83.5 22/125 47.0 1150 6.5 11.1 36.6 75.0 ____________________________________________________________ ______________
The main steps in the production of lubricating oils from petroleum fractions are (a) aromatics removal giving an improved viscosity index and (b) dewaxing giving an improved pour point. Both steps normally use solvents to obtain the desired results, but hydro-catalytic alternatives have also been proposed for both steps. Each of the four processes has its advantages and disadvantages. In the present invention the four processes are combined in a particular way to make the best use of the potential of each process and to avoid using processes for duties for which they are not suited.
According to the present invention, a process for the production of a range of lubricating oils comprises separating a petroleum fraction boiling above 350°C into at least one lighter fraction and at least one heavier fraction, subjecting some or all of the lighter fraction or fractions to a hydro-catalytic dewaxing process and a solvent extraction process for the removal of aromatics and subjecting some or all of the heavier fraction or fractions to a hydrocatalytic viscosity index improvement process and a solvent dewaxing process.
The term "lubricating oil" as used in this specification includes lubricating oils for any use and also speciality oils boiling within the lubricating oil boiling range, e.g., transformer oils. A particular feature of the present invention is that it allows the production of a wide range of oils from light spindle oils to heavy automative oils derived from bright stocks.
Preferably the cut point between the lighter and heavier fraction or fractions is in the range 450° to 500°C.
The number of products obtained from the lighter fraction may conveniently be from 2 to 4, for example spindle oils and the two lightest grades of automotive lubricating oils.
The lighter fraction or fractions are treated, as indicated above, by the combination of hydrocatalytic dewaxing and solvent extraction to remove aromatics. The processes may be used in either order, but, preferably, the hydro-catalytic dewaxing is first. The sequence may treat a single wider boiling range fraction with subsequent distillation to give the required products, or may treat a series of fractions in blocked operation, the latter being preferred.
The preferred hydro-catalytic dewaxing process comprises passing the lighter fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table incorporated with a crystalline mordenite of reduced alkali metal content together with hydrogen at a temperature of from 250° - 500°C and a pressure of from 7 to 200 bars gauge. It may follow the general procedure described and claimed in our UK Pat. Nos. 1088933 and 1134014.
A particular feature and advantage of hydro-catalytic dewaxing is its ability of the process to dewax to low pour points of from -50° to -18°C with the present lighter fractions, which normally have pour points of from 20° to 45°C. Such low pour points cannot be obtained by solvent dewaxing except at exorbitant cost and such low pour points have hitherto been obtained by urea dewaxing, itself a relatively expensive process.
The wax in these lighter fractions is crystalline or paraffinic wax, e.g., n-paraffins or slightly branched paraffins and it is selectively cracked to lower boiling paraffins, particularly C 3 and C 4 paraffins. The selective breakdown of the paraffin wax hydrocarbons is due to the nature of the mordenite based catalyst which promotes the selective attack of these hydrocarbons but not of the other hydrocarbons present in the feedstock.
Suitable process conditions for the catalytic dewaxing include, besides a temperature within the range 250° - 500°C and a pressure within the range 7 - 200 bars gauge as indicated above, a space velocity between 0.1 - 20.0 v/v/hr, and a gas rate of 90 - 3,600 m 3 /m 3 of hydrogen.
Preferred catalytic dewaxing conditions are: Temperature °C 265 - 430 Space velocity v/v/hr 0.5 - 10.0 Pressure bars gauge 40 - 200 Hydrogen gas rate m 3 /m 3 900 - 2700
The term "crystalline mordenite of reduced alkali metal content" means, preferably, a mordenite with an alkali metal content of less than 3% wt. The deficiency of alkali metal cations can be made up with other metal cations for example Group II metal cations, particularly magnesium or rare earth metal cations. Preferably however the mordenite is a "decationised mordenite" which means a mordenite having a deficiency of metal cations. As alternative term in the art is hydrogen mordenite, since it is assumed that when metal cations are removed they are replaced by hydrogen ions. However, since it is not possible to detect the presence of hydrogen ions in zeolites, the precise structure remains in doubt. A cation deficiency can, on the other hand, be readily measured by analysis of the metallic elements present in the zeolite.
Natural or freshly prepared synthetic mordenite has the formula: ##EQU1## where Me is a metal cation, n is the valency of the cation and X is variable between nil and 7 depending on the thermal history of the sample. Me is commonly sodium and in one common form of decationisation sodium mordenite is base exchanged with ammonium cations. The ammonium form is then heated to drive off ammonia, leaving behind the hydrogen form or decationised mordenite. According to the second method the mordenite may be treated with a mineral acid, for example hydrochloric or sulphuric acid, in order directly to decationise the mordenite. A combination of acid treatment and ammonium treatment can also be used.
Preferably the decationised mordenite used in the present invention has a higher than normal silica:alumina ratio of at least 14:1. In specific examples ratios of as high as 90:1 have been obtained and a practical upper limit may thus be 100:1. Particularly preferred silica-alumina ratios are in the range 14:1 to 50:1.
It has been found that certain decationisation treatments remove aluminium as well as the expected metal cations and desirably therefore the mordenite used in the present invention having a higher than normal silica:alumina ratio is obtained by treatment of a metal cation-containing mordenite, particularly sodium mordenite, with a strong acid, for example sulphuric or hydrochloric acid, of from 5 - 50% wt strength and preferably from 10 to 20% wt strength. A single treatment or two or more successive treatments may be given with acids of the strengths stated above.
A convenient method of treatment is to treat the mordenite with acid under reflux for a period of 2 - 12 hours.
In the decationised mordenite the residual metal cation content, for example the sodium cation content, should be less than 3% wt of the mordenite and preferably less than 1.5% wt of the mordenite.
It should be emphasised that mordenites with higher than normal silica/alumina ratios retain the crystal structure of mordenite and are not significantly altered in terms of physical strength, stability or crystallinity.
The hydrogenating component is preferably a platinum group metal, particularly platinum or palladium, and it is preferably added by ion-exchange. The amount of the platinum group metal is preferably within the range 0.01 to 10% wt., particularly 0.1 to 5% wt. However, iron group metals, particularly nickel, also give useful results and they may be used in amounts similar to the platinum group metals. Mixtures of certain Group VI and VIII metals and compounds may also be used, e.g. cobalt and molybdenum.
The catalyst is preferably calcined at for example 250° - 600°C before use to remove any water and to eliminate any ligands attached to the hydrogenation component.
The product from the dewaxing may be distilled to remove light ends boiling below the boiling point of the feedstock, these being, as previously indicated, mostly C 3 and C 4 paraffins which are useful as petrochemical feedstocks or LPG.
The product from the dewaxing is then treated with a selective solvent to remove aromatics. The dewaxing reduces the viscosity index, and irrespective of whether the dewaxing precedes the solvent extraction or not, some VI improvement will usually be necessary to restore at least a part of this VI loss and sometimes to increase it above its original level. With the lighter fractions being treated the product VI's required will normally be within the range 0 to 100, and solvent extraction can produce such VI's efficiency and economically from such feedstocks.
The solvent may be sulphur dioxide/benzene, phenol, glycol, or, preferably, furfural and it may be used in a fixed or rotating disc contactor with from 1 to 20 theoretical extraction stages. The main process variables are solvent:oil ratio, which may be from 0.5 to 5:1 by volume, particularly 1.5 to 4.0:1, average temperature, which may be from 15° to 150°C, particularly 30° - 130°C, and temperature gradient in the column which may be
Column top temperature 150°C maximum Column base 38 - 121°C
Conventional steps of separation of the extract and raffinate and recovery and recycle of solvent may be employed.
The heavier fraction or fractions boiling above the cut point may contain residue possibly together with one or more heavier distillates. This portion of the original feedstock is, as previously indicated, treated by the combination of hydro-catalytic viscosity index improvement and solvent dewaxing. The steps may be used in either order, with, preferably, the viscosity index improvement step first. The feedstock may be treated in bulk with subsequent distillation into product fractions or, preferably, separated first into fractions which are passed through the treatment stages in blocked operation. Preferably it is separated into at least two fractions, one being a vacuum distillate and the other a vacuum residue, parts of which may, if desired, be subsequently reblended.
The vacuum residue portion will contain asphaltenes and possibly organo-metallic compounds, and may, therefore, be de-asphalted prior to the hydro-catalytic treatment step. The de-asphalting solvent may be a low-boiling n-paraffin, particularly propane, which may be used at 20° - 100°C, preferably 40° - 80°C, 5 - 50 bars gauge, preferably 25 - 35 bars gauge, and solvent ratios by volume of 1 - 20:1 preferably 5 - 13:1.
The preferred hydrocatalytic viscosity index improvement step comprises passing the heavier fraction or fractions over a catalyst comprising one or more hydrogenating components selected from Groups VIa and VIII of the Periodic Table on a refractory oxide support together with hydrogen at a temperature of from 340° - 460°C and a pressure of from 70 - 210 bars gauge.
The hydro-catalytic viscosity index improvement step may be used to give products with moderate viscosity index, e.g., 75 - 100 or high viscosity index, e.g., 101 - 150 and a particular advantage of its use is this flexibility. High VI oils are particularly useful not only for certain specialised uses but also in reducing or eliminating the need for viscosity index improvers in multigrade oils, and solvent extractions cannot easily or economically produce such high VI oils.
Thus within the context of hydrocatalytic treatment for VI improvement, two general processes are recognised. These are (i) a relatively mild treatment to give a moderate VI improvement, e.g., 75 to 100 VI after dewaxing with minimum breakdown and decrease in viscosity. Increase in VI of the product to bring it up to multigrade oil requirements, if desired, can be achieved by the use of known polymeric VI improvers (ii) a more severe treatment with extensive breakdown and decrease in viscosity but giving a larger VI improvement, e.g., greater than 100 VI after dewaxing. A larger amount of lower boiling gas oil, kerosene and gasoline byproducts is obtained with the more severe treatment.
The broad ranges of process conditions and the preferred ranges for the two types of process may be chosen from
Milder type More severe Broad range (i) process type (ii) process ______________________________________ Temperature 340 - 460 340 - 430 380 - 460 Pressure bars gauge 70 - 210 70 - 170 120 - 210 Space velocity v/v/hr 0.1 - 5 0.5 - 2 0.2 - 2 Hydrogen gas rate m 3 /m 3 360 - 1800 360 - 1800 360 - 1800 ______________________________________
The refractory inorganic oxide support may be one or more oxides of elements of Groups II, III or IV of the Periodic Table, and may contain halogen. Preferably the amounts of the components of the support are chosen from the following ranges:
Al 2 O 3 10 - 100% wt SiO 2 0 - 90 % wt B 2 O 3 0 - 25 % wt F or Cl 0 - 15 % wt
The hydrogenating component is preferably one or more of the oxides or sulphides of the Group VIa metals (i.e., chromium, molybdenum or tungsten) and the iron group metals (i.e., iron, cobalt or nickel). If platinum group metals are used they are desirably in metallic form.
The amounts of the hydrogenating components may be
Group VIa metals 2 - 25% wt (Expressed as metal) Iron group metals 1 - 15% wt " Platinum group metals 0.1 - 5% wt "
Preferred hydrogenating components are from 2 - 25% wt of molybdenum (expressed as metal but present as oxide or sulphide) and 1 - 15% wt of nickel and/or cobalt (again expressed as metal but present as oxide or sulphide).
For the type (i) process the preferred support has from 50 - 90% wt of Al 2 O 3 and 10 - 50% wt of SiO 2 . The type (ii) process preferably uses the same support, the increased severity being obtained from more severe operating conditions, but, if desired, a more acidic support may be used for example one with 60 - 90% wt SiO 2 and 10 - 40% wt Al 2 O 3 or 85 - 95% wt Al 2 O 3 and 5 - 15% wt F or Cl.
The precise choice and number of heavier fractions treated will depend on the VI improvement required. The greater the VI improvement the greater the drop viscosity and, preferably, at least a proportion of vacuum residue is used with the type (ii) process. Vacuum distillate and/or residue fractions may be used with the type (i) process.
The term viscosity index as used in this specification means that measured by ASTM D2270/64.
In addition to some breakdown to products boiling below 350°C there may be conversion of sulphur and nitrogen compounds to H 2 S and NH 3 . At least the latter is desirably removed, by scrubbing with water, from any gas recycled and products boiling below 350°C are desirably removed by distillation.
The product from the hydrocatalytic viscosity index improvement step is then solvent dewaxed. The heavier product fractions are normally required to have pour points of from -18° to -9°C which can be efficiently and economically produced with solvents. Solvent dewaxing also removes the microcrystalline wax present in these heavier fractions more readily than does catalytic dewaxing.
The solvent may be an alkyl ketone, the alkyl groups being the same or different and having 1 - 4 carbon atoms. Preferred solvents are methyl ethyl ketone, methyl isobutyl ketone or mixtures of the same. An aromatic, e.g., benzene or toluene may also be present, preferably in an amount of from 25 - 75% wt vol of the total solvent. Other suitable solvents are C 1 - C 4 chlorinated hydrocarbons, e.g., methylene chloride or ethylene dichloride or C 2 - C 6 alkanes, particularly propane.
The oil is mixed with solvent and is usually heated to enusre complete solution and is then chilled to precipitate the wax. Solvent:oil ratios may be from 0.5 to 10:1 by volume, preferably 1 to 5:1 and the mixture may be chilled to from -5° to -30°C. The chilling rate may be from 0.5° to 10°C/minute, preferably 2° to 7°C/minute.
The precipitated wax is removed by filtration and the filter cake is washed with cool solvent usually in a solvent/oil ratio of 0.2:1 - 8:1. The dewaxed oil is freed from solvent by distillation the solvent being recycled for re-use. Similarly the precipitated wax and the wash solvent may be separated into product and solvent fractions by distillation.
While the invention, in its broadest aspect, splits the feedstock into two main streams, further sub-division is possible with a third stream taking a wholly solvent route, a fourth stream being subjected only to solvent dewaxing and possibly a fifth stream taking a wholly catalytic route.
The present invention, therefore, includes a process for the production of a range of lubricating oils comprising separating a petroleum fraction boiling above 350°C into at least one lighter fraction and at least two heavier fractions, subjecting the lighter fraction or fractions to a hydrocatalytic dewaxing process and a solvent extraction process for the removal of aromatics, subjecting at least one of the heavier fractions to a hydrocatalytic viscosity index improvement process and a solvent dewaxing process and subjecting at least one other of the heavier fractions to a solvent extraction process for the removal of aromatics and a solvent dewaxing process.
Such a three-stream process is particularly suitable when it is desired to produce both 75 - 100 VI and 101 - 150 VI products from the heavier fractions, the former being produced from the wholly solvent stream and the latter from the mixed catalytic and solvent route.
In a further embodiment the feedstock may be separated into three or more heavier fractions, at least one of which is subjected to a hydrocatalytic viscosity index improvement process and a solvent dewaxing process, at least another one of which is subjected to a solvent extraction process for the removal of aromatics and a solvent dewaxing process, and at least another one of which is subjected to a solvent dewaxing process without either a hydrocatalytic viscosity index improvement process or a solvent extraction process for the removal of aromatics.
All or any of the product fractions may be finished in known manner to improve colour, oxidation stability or light stability. Thus they may be treated with clay or bauxite, or, preferably, given a mild hydrocatalytic treatment known as hydrofinishing. Such finishing treatments may be less necessary with the lighter catalytically dewaxed fractions.
The present invention may be used with a new lubricating oil plant or can be used to expand an existing plant formed of solvent extraction and solvent dewaxing units. It has been found that the addition of two catalytic units to an existing plant of two solvent units gives a reduction of up to 10% in capital cost as compared with adding two further solvent units or one further solvent unit and one catalytic unit. This advantage is in addition to the other advantages of flexibility, usage of individual processes in the most efficient manner and the ability to produce from a single plant, oils ranging from light oils with a viscosity of 22 cSt at 100°F (38°C) and a pour point of -40°C to heavy oils with a viscosity of 1,200 cSt at 100°F (38°C) and a pour point of -12°C.
The invention is illustrated with reference to the accompanying drawing which is a flow diagram of a lubricating oil production process according to the present invention. The drawing is based on the expansion of an existing lubricating oil unit with existing plant indicated by shading.
In the drawing, the plant consists of two vacuum distillation columns 1, 2, two propane deasphalting units 3, 4, a catalytic dewaxing unit 5, a catalytic hydrogenating unit 6, a furfural extraction unit 7 and a solvent dewaxing unit 8.
Atmospheric residue with an initial boiling point of 250°C is fed through lines 9, 10 to the vacuum distillation columns 1, 2. Each column separates the atmospheric residue into light ends boiling below 350°C which are taken off overhead through lines 11, 12 for disposal elsewhere, 4 distillate fractions A, B, C, D, and A 1 , B 1 , C 1 , D 1 and a residue fraction E and E 1 . Distillates A, B, C are passed through lines 13, 14, 15 to the catalytic dewaxing unit 5. All or part of distillates A 1 , B 1 and C 1 can also be passed, if desired, to the catalytic dewaxing unit 5 through lines not shown. The catalytically dewaxed distillates then pass to the furfural extraction unit 7 and are recovered as A 2 , B 2 and C 2 products through lines 16, 17 and 18. Before the furfural extraction unit, the distillate C stream is split, part of it, going separately through the furfural extraction unit at different extraction conditions and then, via line 19, for blending with a stream described hereafter.
Distillate D goes via line 20 (together with distillate D 1 if desired) to the catalytic hydrogenation unit 6 and then to the solvent dewaxing unit 8 being recovered as product D 2 through line 21 after blending with a portion of distillate C from line 19 and a portion of residue E 1 from line 30. Residue E passes through line 22 to the propane deasphalting unit 3 and is then split into three. Part goes through line 23 to the catalytic hydrogenation unit 6, part goes through line 24 to the furfural extraction unit 7 and part by-passes both units, going direct to the solvent dewaxing unit 8 through line 25. The part going through line 23 is blended with distillate D from line 20 and thus eventually becomes part of product D 2 . The part going via line 24 through the furfural extraction unit then passes to the solvent dewaxing unit emerging through line 26 as product E 3 . The part going through line 25 direct to the solvent dewaxing unit emerges as product E 4 through line 27.
Residue E 1 is sent via line 28 to the propane deasphalting unit 4, the catalytic hydrogenation unit 6, and the solvent dewaxing unit 8 emerging through line 29 as product E 2 . Part of this product, as indicated above, is blended with product D 2 through line 30.
The invention is illustrated by the following example.
Example
A range of lubricating oils was produced from an atmospheric residue of a Kuwait crude oil using the process scheme described above. The grades produced and the feedstocks used are shown in Table 1 below.
Table 1 ______________________________________ Grade Feedstock ______________________________________ Transformer oil Vacuum Gas Oil 20S A cut 33/100 B cut 110/75 C cut 22/125 C cut 110/95 50% DAO, 50% D cut 550/95 DAO 750/85 DAO ______________________________________
In the grades, 20 S was a spindle oil of 4.1 cSt at 210°F.
In the other grades the first figure refers to the viscosity in cSt measured at 100°F and the second figure to the viscosity index.
The feedstocks were produced by vacuum distillation of the atmospheric residue. The vacuum gas oil cut was collected overhead and had a boiling range of 210°-410°C and a viscosity of 2.0 cSt at 210°F. The A, B, C and D cuts were side streams having the following characteristics.
______________________________________ TBP Cut Boiling Range Viscosity (determined by GLC) cSt at 210°F) ______________________________________ A 330 - 460 3.9 B 360 - 495 6.1 C 350 - 580 9.4 D -- 14.4 ______________________________________
Where blends of cuts were used, the percentages were by volume. The residue was deasphalted using propane as solvent to give deasphalted oil (DAO) having a viscosity of 36.5 cSt at 210°F.
The first four grades were produced from the indicated feedstocks by a combination of catalytic dewaxing and furfural extraction.
The catalytic dewaxing conditions were
Temperature °C 320-400°C Pressure bars gauge 69 Gas recycle rate m 3 /m 3 1684 LHSV v/v/hr 1.0 Catalyst 0.5% wt. platinum on mordenite decationised to a Na content of 0.75% wt. and acid treated to a silica:alumina ratio of 18:1.
The recycle gas was scrubbed to reduce the H 2 S content to a maximum of 500 ppm vol. of H 2 S at the reactor outlet and the NH 3 content to less than 5 ppm vol.
The yields from the catalytic dewaxing and the furfural treatment, and the amount of furfural used are shown in Table 2.
TABLE 2 ____________________________________________________________ ______________ Catalytic Dewaxing Furfural Extraction ____________________________________________________________ ______________ Dewaxed Chemical Gas Gasoline Furfural Extraction Grade Lube Hydrogen Yield Yield Treatment Yield Yield Consumption % wt. % wt. % vol. % wt. % wt. scf/brl. C 1 -C 5 C 5 -117°C ____________________________________________________________ ______________ Transformer Oil 70 300 26.0 4.0 100 55 20S 82 200 14.0 4.0 80 75 33/100 82.5 280 12.5 5.0 400 48 110/75 80 400 16.0 4.0 200 68 ____________________________________________________________ ______________
The remaining four grades were produced from the indicated feedstocks by a combination of hydrogenation and solvent dewaxing.
The hydrogenation conditions were
22/125 Other Grade Grades ______________________________________ Temperature °C 400-420 350-420 Pressure bars gauge 138 138 Gas recycle rate m 3 /m 3 1684 1250 LHSV v/v/hr 0.5 1.0 Catalyst 1.75% wt Co and 12.7% wt Mo on silica alumina, having a silicon content of 9% wt. by weight of the support. ______________________________________
The solvent dewaxing conditions were
Temperature °C -12 to -18 Solvent/oil ratio 6:1 to 12:1 Solvent Methyl Isobutyl Ketone
The yields from the processes are shown in Table 3.
TABLE 3 ____________________________________________________________ ______________ Hydrogenation Data Dewaxing Data ____________________________________________________________ ______________ Waxy Chemical Gas Gasoline Middle Product Grade Lube Hydrogen Yield Yield Distillate Yield Yield Consumption % wt. % wt. Yield % wt. % wt. scf/brl C 5 -177°C % wt. 177-371°C ____________________________________________________________ ______________ 110/95 81.0 720 5.3 4.8 12.5 83.5 550/95 90.7 500 3.1 0.3 6.8 83.5 750/85 96.0 330 1.2 0.4 2.5 83.5 22/125 47.0 1150 6.5 11.1 36.6 75.0 ____________________________________________________________ ______________