PROCESS FOR MANUFACTURING LUBRICATING OIL
United States Patent 3793191
A process for manufacturing a lubricating oil comprising a first step of passing a deasphalted crude oil distillation residue containing by weight at least 85 percent of constituents boiling above 500°C and at least 75 percent of consituents boiling above 525°C, with hydrogen over a hydrogenating catalyst with a cracking carrier at 330°-450°C, at a hydrogen partial pressure of 80-240 kg/cm2, at such a flow rate that the hydrocarbons in the resulting product boiling below 525°C amount to 70-95 percent of the initial weight of such hydrocarbons, separating the products boiling below 525°C, and recovering a first lubricating oil fraction of high V.I. and a second step of passing at least a portion of the products boiling above 525°C over a similar catalyst, at the same temperature and pressure ranges of the first step, at such a flow rate that the major part of the first zone heavy products are converted to products boiling below 525°C and separating therefrom, by distillation, a second lubricating oil fraction.
US Patent References:
TWO-STAGE CATALYTIC HYDROGEN PROCESSING OF A LUBE OIL
Gallagher et al. - February 1970 - 3494854
/3560370.html
Billon et al. - February 1971 - 3560370
PROCESS FOR STABILIZING LUBRICATING OIL
Langlois et al. - August 1969 - 3463724
PROCESS FOR ENHANCING LUBRICATING OILS AND A CATALYST FOR USE IN THE PROCESS
Henke et al. - March 1970 - 3493493
Production of lubricating oil
Paterson - March 1966 - 3242068
TWO-STAGE CATALYTIC HYDROGEN PROCESSING OF A LUBE OIL
Gallagher et al. - February 1970 - 3494854
/3560370.html
Billon et al. - February 1971 - 3560370
PROCESS FOR STABILIZING LUBRICATING OIL
Langlois et al. - August 1969 - 3463724
PROCESS FOR ENHANCING LUBRICATING OILS AND A CATALYST FOR USE IN THE PROCESS
Henke et al. - March 1970 - 3493493
Production of lubricating oil
Paterson - March 1966 - 3242068
Inventors:
Billon, Alain (Lyon, FR)
Derrien, Michel (Rueil-Malmaison, FR)
Derrien, Michel (Rueil-Malmaison, FR)
Application Number:
05/241690
Publication Date:
02/19/1974
Filing Date:
04/06/1972
View Patent Images:
Export Citation:
Assignee:
Institut Francais, Du Petrole Des Carburants Et Lubrifiants (Rueil-Malmaison, FR)
Primary Class:
Other Classes:
208/18, 502/255
International Classes:
C10G65/10; C10G65/00; C10G13/06; C10G37/10
Field of Search:
208/59
US Patent References:
Primary Examiner:
Gantz, Delbert E.
Assistant Examiner:
Schmitkons G. E.
Attorney, Agent or Firm:
Millen, Raptes & White
Claims:
What we claim as this invention is
1. A process for manufacturing a lubricating oil comprising passing a deasphalted distillation residue of crude oil containing at least 85 percent by weight of constituents boiling above 500° C. and at least 75 percent by weight of constituents boiling above 525° C. with hydrogen through a first catalytic zone containing a hydrogenating element and a cracking carrier consisting essentially of, by weight, 2 - 10 percent cobalt or nickel, 10 - 30 percent molybdenum or tungsten, 5 - 40 percent silica and 22 - 83 percent alumina, with a weight ratio of Al2 O3 to SiO2 of 1.5 - 6, at a temperature of from 330° to 450° C. and a hydrogen partial pressure of from 80 to 240 kg/cm2, at such a flow rate that the hydrocarbons boiling below 525° C. in the resulting product amount to 70 to 95 percent of the initial weight of such hydrocarbons, separating relatively light products boiling below 525° C. and recovering a first lubricating oil fraction of high V.I., passing at least a portion of relatively heavy products boiling above 525° C. together with hydrogen through a second catalytic zone containing a hydrogenating element and a cracking carrier consisting essentially of, by weight, 2 - 10% cobalt or nickel, 10°- 30 percent molybdenum or tungsten, 25 - 75 percent silica and 2 - 75 percent alumina, with a ratio by weight of Al2 O3 to SiO2 of 0.1 - 1, at a temperature of from 330° to 450° C. and a hydrogen partial pressure of from 80 to 240 kg/cm2, at such a flow rate that at least the major part of said relatively heavy products of said first zone is converted to products boiling below 525° C., and distilling the resulting products to separate a second lubricating oil fraction.
2. A process according to claim 1, wherein the operating conditions in the first catalytic zone are such that the weight of the hydrocarbons boiling below 525°C, in the resulting product, amounts to from 85 to 92 percent of the initial weight of such hydrocarbons.
3. A process according to claim 1, wherein the deasphalted residue has an initial boiling point higher than 300°C, and contains at least 90 percent by weight constituents having a boiling point higher than 500°C.
4. A process according to claim 3, wherein the deasphalted residue has a viscosity at 98.9°C of from 5 to 100 centistokes.
5. A process according to claim 4, wherein the deasphalted residue has a viscosity of from 5 to 50 centistokes at 98.9° C., a viscosity index of from 0 to 100, a maximum content of asphaltenes of 0.3 percent by weight, a nitrogen content lower than 0.3 percent by weight and a maximum Conradson carbon of 5 percent by weight.
6. A process according to claim 1, wherein the flow rate of liquid charge is from 0.1 to 2 liters per liter of catalyst per hour and the hydrogen flow rate is from 500 to 5,000 liters per liter of liquid charge in each of the two catalytic zones.
7. A process according to claim 1, further comprising blending the first and second lubricating oil fractions, so as to obtain a blend of high V.I. lubricating oils.
8. A process according to claim 1 wherein the flow rate of the liquid charge in the second catalytic zone, expressed in liters per liter of catalyst per hour, is from 1.2 to 2 times that of the first catalytic zone.
9. A process according to claim 1, wherein the temperature in the second catalytic zone is 10° to 100°C lower than the temperature in the first catalytic zone.
1. A process for manufacturing a lubricating oil comprising passing a deasphalted distillation residue of crude oil containing at least 85 percent by weight of constituents boiling above 500° C. and at least 75 percent by weight of constituents boiling above 525° C. with hydrogen through a first catalytic zone containing a hydrogenating element and a cracking carrier consisting essentially of, by weight, 2 - 10 percent cobalt or nickel, 10 - 30 percent molybdenum or tungsten, 5 - 40 percent silica and 22 - 83 percent alumina, with a weight ratio of Al2 O3 to SiO2 of 1.5 - 6, at a temperature of from 330° to 450° C. and a hydrogen partial pressure of from 80 to 240 kg/cm2, at such a flow rate that the hydrocarbons boiling below 525° C. in the resulting product amount to 70 to 95 percent of the initial weight of such hydrocarbons, separating relatively light products boiling below 525° C. and recovering a first lubricating oil fraction of high V.I., passing at least a portion of relatively heavy products boiling above 525° C. together with hydrogen through a second catalytic zone containing a hydrogenating element and a cracking carrier consisting essentially of, by weight, 2 - 10% cobalt or nickel, 10°- 30 percent molybdenum or tungsten, 25 - 75 percent silica and 2 - 75 percent alumina, with a ratio by weight of Al2 O3 to SiO2 of 0.1 - 1, at a temperature of from 330° to 450° C. and a hydrogen partial pressure of from 80 to 240 kg/cm2, at such a flow rate that at least the major part of said relatively heavy products of said first zone is converted to products boiling below 525° C., and distilling the resulting products to separate a second lubricating oil fraction.
2. A process according to claim 1, wherein the operating conditions in the first catalytic zone are such that the weight of the hydrocarbons boiling below 525°C, in the resulting product, amounts to from 85 to 92 percent of the initial weight of such hydrocarbons.
3. A process according to claim 1, wherein the deasphalted residue has an initial boiling point higher than 300°C, and contains at least 90 percent by weight constituents having a boiling point higher than 500°C.
4. A process according to claim 3, wherein the deasphalted residue has a viscosity at 98.9°C of from 5 to 100 centistokes.
5. A process according to claim 4, wherein the deasphalted residue has a viscosity of from 5 to 50 centistokes at 98.9° C., a viscosity index of from 0 to 100, a maximum content of asphaltenes of 0.3 percent by weight, a nitrogen content lower than 0.3 percent by weight and a maximum Conradson carbon of 5 percent by weight.
6. A process according to claim 1, wherein the flow rate of liquid charge is from 0.1 to 2 liters per liter of catalyst per hour and the hydrogen flow rate is from 500 to 5,000 liters per liter of liquid charge in each of the two catalytic zones.
7. A process according to claim 1, further comprising blending the first and second lubricating oil fractions, so as to obtain a blend of high V.I. lubricating oils.
8. A process according to claim 1 wherein the flow rate of the liquid charge in the second catalytic zone, expressed in liters per liter of catalyst per hour, is from 1.2 to 2 times that of the first catalytic zone.
9. A process according to claim 1, wherein the temperature in the second catalytic zone is 10° to 100°C lower than the temperature in the first catalytic zone.
Description:
This invention concerns an improved process for manufacturing lubricating oils from vacuum deasphalted residues which may, in some cases, contain a minor proportion of vacuum distillates.
It provides, more particularly, oils exhibiting high viscosimetric properties and a satisfactory content of hetero-atoms (particularly sulphur and nitrogen) with moderate manufacturing costs and a relatively narrow distillation range.
This process consists in performing a hydrotreatment in two stages, under the conditions stated below, of a charge consisting essentially of a deasphalted vacuum distillation residue.
The process for manufacturing the lubricating oil is remarkable in that it comprises passing a deasphalted distillation residue of crude oil containing at least 85 percent by weight of constituents boiling above 500°C and at least 75 percent by weight of constituents boiling above 525°C, together with additional hydrogen, through a first catalytic zone containing a hydrogenating element and a cracking carrier, at a temperature of from 330° to 450°C and a hydrogen partial pressure of from 80 to 240 kg/cm 2 , with such a flow rate that, in the resulting product, the weight of hydrocarbons boiling below 525°C amounts to from 70 to 95 percent of the initial weight of such hydrocarbons, separating the relatively light products boiling below 525°C, and recovering a first lubricating oil fraction of high V.I. passing at least a portion of relatively heavy products, boiling above 525°C, together with hydrogen, through a second catalytic zone containing a hydrogenating element and a cracking carrier, at a temperature of from 330° to 450°C and a hydrogen partial pressure of from 80 to 240 kg/cm 2 , with such a flow rate that at least the major part of said relatively heavy products is converted to products of said first zone boiling below 525°C and distilling the resulting products for separating a second lubricating oil fraction.
If so desired, the treatment of the second step can be performed only on heavy products having an initial boiling point substantially higher than 525°C, for example 570°C or more.
Preferably, at the end of the first step, the hydrocarbons boiling below 525°C will amount to from 85 to 92 percent by weight of the initial hydrocarbons. It is essential, according to the invention, to comply with the limits of 70 to 95 percent, for the proportion of products boiling below 525°C at the end of the first step. As a matter of fact, higher values will result in a quick deactivation of the catalyst; for lower values, the resulting oil will have a low viscosity index.
Unless otherwise indicated, all boiling points given herein are for a pressure of 1 atmosphere absolute.
The process will now be described with reference to the accompanying drawing which shows by way of example, an overall diagram of a unit operated according to the process of the invention.
Through line 1 is fed a charge formed of a preliminarily deasphalted vacuum distillation residue of a raw petroleum or of a mixture of such a residue with a vacuum distillate.
The deasphalting may be achieved according to any known technique for example, by treatment with of lower paraffinic hydrocarbons, such as propane, butane or a mixture of propane and butane.
This charge is preferably so selected as to have the following characteristics:
initial boiling point higher than 300°C, at least 85 percent of the constituents of the charge having a boiling point higher than 500°C and at least 75 percent of said constituents having a boiling point higher than 525°C;
a viscosity at 98°9 C in the range of from 5 to 100 cst, preferably from 5 to 50 cst;
a viscosity index from 0 to 100;
the following maximum contents:
a. asphaltenes: 0.3 % by weight
b. nitrogen: 0.3 % by weight
c. Conradson carbon: 5 % by weight
The charge preliminarily admixed with fresh hydrogen and conveyed through line 1' is heated in the oven 2 and then conveyed through line 3 to the first hydrotreatment reactor 4. This reactor is also fed with a gas rich in molecular hydrogen introduced through line 5. Of course, hydrogen may be introduced before or after the passage of the charge through the oven 2. In reactor 4, comprising one or more catalytic beds, there is achieved the hydrogenation of the unsaturated compounds of the charge (and particularly of the alkyl aromatic compounds) as well as at least a partial cracking of the naphthenic compounds present in the charge or obtained by hydrogenating said charge in reactor 4.
The operating conditions of reactor 4 are preferably as follows:
L.H.S.V. from 0.1 to 2 liters of liquid charge per liter of catalyst and per hour;
ratio of the flow rate of pure gaseous hydrogen to the flow rate of liquid charge in the range of from 500 to 5,000 liters per liter;
hydrogenating gas (line 5): hydrogen purity higher conveyed through line 13 to an oven 14 and then through line 15 to a first distillation column 16 operated under a pressure close to the atmospheric.
There is thus separated several fractions, for example light hydrocarbons C 1 --C 4 through line 17, a fraction boiling in the gasoline range through line 18 and gas-oil through line 19.
The distillation residue is conveyed through line 20 and after passage through a second oven sent to a second distillation column 22 operated under reduced pressure.
There is thus obtained a heavy gas-oil from line 23 and different oil fractions from lines 24, 25 and 26.
The products issuing from the second distillation column have a content of sulphur impurities lower than 0.1 percent by weight and generally lower than 0.02 percent.
Nitrogen amounts to less than 30 ppm by weight (parts per million of parts of oil).
The Conradson carbon amounts to less than 0.10 percent by weight and generally less than 0.05 percent.
It has been mentioned that the hydrotreatment to which the charge is subjected in the reactor 4 is equivalent to a hydrogenation combined with a cracking; this operation is accompanied with a formation of hydrogen sulphide H 2 S, ammonia NH 3 and very light hydrocarbons, more particularly methane.
These three compounds and more particularly the former two flow essentially from the separator 8 as a mixture with unconsumed hydrogen (a much smaller portion is discharged through duct 12). It is important, when it is desired to recycle the unconsumed hydrogen, to remove completely the than 60 percent (by volume), percentage of CO + CO 2 being at most 2.5 percent. The catalyst may for example contain:
from 2 to 10 percent by weight of cobalt or nickel (expressed as CoO or NiO);
from 10 to 30 percent by weight of molybdenum or tungsten (expressed as MoO 3 or WO 3 );
from 5 to 40 percent by weight of silica and from 22 to 83 percent by weight of alumina (with a preferred ratio by weight of Al 2 O 3 to SiO 2 in the range of from 1.5 to 6).
The outflow from the hydrotreatment reactor is directed, through line 6, to a first gas-liquid separator or flash 8, also called high pressure separator (HP).
The temperature of the mixture flowing through duct 6 has been previously lowered by passage of the mixture through the cooler 7.
In the separator 8 there is recovered, at one end, a liquid phase conveyed through line 9 to a second separator 10, called low pressure separator (LP) and, at the other end, a gaseous mixture rich of hydrogen and flowing through duct 11.
A portion of said gaseous stream is removed, the other being recycled, through line 5, to the hydrotreatment reactor 4. The gas removed from the system may be used for other purposes, for example as combustible gas.
The operation of the separator 10 is similar to that of the first separator except that the pressure is considerably lower (a few kg/cm 2 instead of several tens or even hundreds of kg/cm 2 ).
There is obtained, at the outlet of the second separator, a gaseous mixture removed through line 12 and a liquid phase ammonia and partially the hydrogen sulfide and the very light hydrocarbons. This is achieved by known means.
Various particularly interesting solutions are described in the French patent 1 582 758.
According to a known process, the vacuum distillation residue containing at least 50 percent by weight of constituents boiling above 525°C, withdrawn through duct 27, may either be considered as a base oil and used as such, or may be recycled into the reactor 4.
In the latter case, a mere recycling has many inconveniences: as a matter of fact, the recycled residue being formed of molecules of high molecular weights relatively unaffected by the hydrotreatment, its recycling to the reactor 4 results in a decrease of the catalyst activity and accordingly requires more severe operating conditions for its conversion to lighter products.
The distillate withdrawn from lines 24, 25 and 26 must have relatively constant characteristics. The recycling of the distillation residue through line 27 into the reactor 4, having after a long time the detrimental effect of modifying the catalyst activity, results accordingly in a much more rapid modification of the characteristics of the desired products; in particular it has been observed during the cycle, that the aromatic content suffers substantial changes in the recycled residue and, to a lower degree, in the distillates withdrawn from lines 24, 25 and 26.
It has now been discovered that by passing, during a second step, the distillation residue withdrawn from line 27 through a second reactor containing a catalyst identical to or different from that of the first reactor, it is possible to convert partially or entirely the distillation residue to lighter products while avoiding the above-mentioned drawbacks. This distillation residue, which has been subjected to a substantial conversion during its passage in reactor 4, has a very high paraffinic character and a small content of impurities:
Nitrogen ≤ 100 ppm by weight
Sulphur ≤ 500 ppm by weight
Conradson carbon ≤ 0.1 % by weight
Asphaltenes ≤ 0.05 % by weight
According to the process of the invention, this distillation residue is withdrawn through line 27, heated in the oven 28, optionally after being admixed with fresh hydrogen conveyed through line 27', then sent through line 29 to a second hydrotreatment reactor 30, optionally fed with a gas rich of molecular hydrogen introduced through line 34.
The operating conditions of reactor 30 are preferably as follows:
L.H.S.V. of from 0.1 to 2 liters of liquid charge per liter of catalyst and per hour.
Ratio of the flow rate of pure gaseous hydrogen to the flow rate of liquid charge from 500 to 5,000 liters per liter.
Preferably, the operating conditions in the second reactor 30 are not so severe as those in the first reactor 4, i.e. the L.H.S.V. is higher (1.2 to 2 times higher than the L.H.S.V. in reactor 4), and the temperature lower (for example from 10° to 100°C lower than the temperature in reactor 4); the hydrogen partial pressures being the same in reactors 4 and 30.
Reactor 30 comprises, as well as reactor 4, at least one catalyst bed. The catalyst may, for example, contain:
from 2 to 10 percent by weight of cobalt or nickel (expressed as CoO or NiO)
from 10 to 30 percent by weight of molybdenum or tungsten (expressed as MoO 3 or WO 3 )
from 25 to 75 percent by weight of silica and from 2 to 75 percent by weight of alumina (with a preferred ratio by weight of Al 2 O 3 to SiO 2 in the range of from 0.1 to 1).
Alumina may be amorphous or crystallized; in the latter case, suitably exchanged zeolites may be incorporated thereto (zeolites with a sodium, calcium or lanthanum base by way of example). The zeolitic portion amounts for example to 3 to 15 percent by weight of the total catalyst.
Other catalysts for use in the first or second stage of the process may contain at least one noble metal from group VIII, for example platinum, and at least one carrier such as alumina-silica, chlorinated alumina or fluorinated alumina. Molybdenum or tungsten may also be used, with or without nickel or cobalt, on a halogenated alumina carrier. Other equivalent catalysts, known in the art, may also be used.
The effluent from the hydrotreatment reactor is conveyed through lines 31 and 33 to the first gas-liquid separator 8.
The temperature of the mixture flowing through duct 6 has been previously lowered by passage of the mixture through the cooler 32.
The recycling according to the invention, by passage of the distillation residue to a second reactor, avoids the above mentioned inconveniences. Moreover, this treatment gives a very high flexibility to the process of manufacturing lubricating oils. Particularly, it provides for the possibility, at the desired V.I. level, of maximizing the yields of oily distillates withdrawn from lines 24, 25 and 26 and of changing the distribution of these fractions according to the demand on the markets.
The accompanying drawing is only a simplified diagram of a unit operated according to the invention. Of course, there can be obtained, according to the nature of the charge and the severity of the treatment, a higher or lower number of oil fractions ranging from the "Spindle-oil" type to the "heavy distillate" type (three fractions are shown, by way of example, on the FIGURE). This is also true for the first distillation column 16, particularly with respect to the different fractions obtained (in addition to the residue circulating through line 20).
The different oil fractions obtained from the second distillation are generally subjected to a dewaxing treatment not illustrated on the FIGURE (for example by a mixture methylethylketone-toluene) before being used as base oils to which various additives are generally incorporated.
As hereabove indicated, the FIGURE is only a simplified diagram on which the pumps, compressors, and the like are not shown. The reactor, the distillation columns, the cooler are apparatuses of the type commonly used for this kind of operation.
EXAMPLE
Manufacture of Bases for Multigrade Oils
EXAMPLE 1
The charge is a deasphalted residue having the following composition:
d 4 20 =0.928 S =2.58 % by weight N =800 ppm by weight Conradson carbon =1.80 Viscosity at 98.9°C =35.7 cst Distillation ASTM-1160 =7 % distilled at 500°C 15 % distilled at 525°C 85 % having a boiling point higher than 525°C
the reaction conditions are as follows:
PH 2 =140 kg/cm 2 T =410°C L.H.S.V. =0.7 liter per liter of catalyst and per hour. Hydrogen flow rate (RH 2 ) =1,000 liters per liter of liquid charge
The charge, at the outlet of the first reactor (line 6), has the following composition: (% by weight)
H 2 S+NH 3 2.84 C 1 +C 2 0.42 C 3 +C 4 1.62 C 5 +C 6 2.60 Gasoline 80°-150°C 6.20 Gas-oil 38.42 Oily base 50.00
This base oil, distilled under reduced pressure, gives the following fractions:
100 Neutral: 25% i.e. 12.5% by weight of the initial charge
180 Neutral: 30% i.e. 15 % by weight of the initial charge
400 Neutral: 25 % i.e. 12.5 % by weight of the initial charge
The distillation is discontinued when the temperature (corrected at the atmospheric pressure) reaches 525°C. The remaining distillation residue thus amounts to 20 percent of the base oil, i.e. : 10 percent by weight of the initial charge.
The catalyst used in the first reactor had the following composition:
Composition: Al 2 O 3 56 % (by weight) SiO 2 20 % MoO 3 16 % NiO 8 % Specific surface 250 m 2 /g Total porous volume 55 cc/100g Microporous volume 33 cc/100 g (<0.1μ) Macroporous volume 22 cc/100 g (>0.1μ)
According to the process of the invention the distillation residue is conveyed to a second reactor. The reaction conditions are as follows:
PH 2 =140 kg/cm 2 T =380°C L.H.S.V. =1 liter per liter of catalyst and per hour RH 2 =1,000 liters per liter of liquid charge
The catalyst of the second reactor has the following composition:
Composition: Al 2 O 3 21 % (by weight) SiO 2 55 % WO 3 20 % NiO 4 % Specific surface 250 m 2 /g Total porous volume 55 cc/100 g
The product obtained at the outlet of the second reactor contains 40 percent of light products, which will be later withdrawn from lines 17, 18 and 19 and 60 percent of a base oil. These 60 percent of base oil correspond to 6 percent of the initial charge, since the distillation residue amounted to 10 percent of the initial charge. These 6 % are distributed as follows:
100 Neutral: 2.4 % by weight of the initial charge
180 Neutral: 1.8 % by weight of the initial charge
400 Neutral: 1.8 % by weight of the initial charge
There is no residue.
As a total, there are thus obtained from lines 24, 25 and 26:
12.5+2.4=14.9 % 100 Neutral 15+1.8=16.8 % 180 Neutral 12.5+1.8=14.3 % 400 Neutral
The characteristics of the total base oil (mixture of the products from the first and the second steps) is as follows: viscosity at 98.9°C = 8 cst, V.I. = 125.
The viscosity index (V.I.) has been determined according to the method defined by the Standard ASTM D-567.
The impurity content of this global base oil is very low.
S > 0.01 % (by weight)
N > 1 ppm
Conradson Carbon ≤ 0.02
It has been possible to operate this process over a period of at least 12 months without any catalyst regeneration.
By way of comparison, there has been used a single reactor into which the unconverted residue is recycled. In these conditions, it was necessary to regenerate the catalyst after 2 or 3 months. Moreover, in the latter case, the composition of the base oil is variable during time, because of the adjustments of the catalyst temperature, required for compensating its deactivation.
In this example, all the distillation residue has been converted to light products in the second reactor. But it must be stated that, according to the charge and the required distribution of the oils, the conversion in the second reactor may be either complete or partial. In the latter case, the distillation residue obtained from the initial charge and the distillation residue obtained from the residue treated in the second reactor are withdrawn through line 27 and conveyed together to the second reactor.
EXAMPLE 2
Example 1 is repeated except that the following catalysts are used:
First reactor: Al 2 O 3 60 % (by weight) SiO 2 15 % WO 3 18 % CoO 7 % Second reactor: Al 2 O 3 18 % (by weight) SiO 2 57 % MoO 3 20 % CoO 5 %
The total yield by weight is as follows:
100 Neutral 14.7 % 180 Neutral 16.6 % 400 Neutral 14.5 %
It provides, more particularly, oils exhibiting high viscosimetric properties and a satisfactory content of hetero-atoms (particularly sulphur and nitrogen) with moderate manufacturing costs and a relatively narrow distillation range.
This process consists in performing a hydrotreatment in two stages, under the conditions stated below, of a charge consisting essentially of a deasphalted vacuum distillation residue.
The process for manufacturing the lubricating oil is remarkable in that it comprises passing a deasphalted distillation residue of crude oil containing at least 85 percent by weight of constituents boiling above 500°C and at least 75 percent by weight of constituents boiling above 525°C, together with additional hydrogen, through a first catalytic zone containing a hydrogenating element and a cracking carrier, at a temperature of from 330° to 450°C and a hydrogen partial pressure of from 80 to 240 kg/cm 2 , with such a flow rate that, in the resulting product, the weight of hydrocarbons boiling below 525°C amounts to from 70 to 95 percent of the initial weight of such hydrocarbons, separating the relatively light products boiling below 525°C, and recovering a first lubricating oil fraction of high V.I. passing at least a portion of relatively heavy products, boiling above 525°C, together with hydrogen, through a second catalytic zone containing a hydrogenating element and a cracking carrier, at a temperature of from 330° to 450°C and a hydrogen partial pressure of from 80 to 240 kg/cm 2 , with such a flow rate that at least the major part of said relatively heavy products is converted to products of said first zone boiling below 525°C and distilling the resulting products for separating a second lubricating oil fraction.
If so desired, the treatment of the second step can be performed only on heavy products having an initial boiling point substantially higher than 525°C, for example 570°C or more.
Preferably, at the end of the first step, the hydrocarbons boiling below 525°C will amount to from 85 to 92 percent by weight of the initial hydrocarbons. It is essential, according to the invention, to comply with the limits of 70 to 95 percent, for the proportion of products boiling below 525°C at the end of the first step. As a matter of fact, higher values will result in a quick deactivation of the catalyst; for lower values, the resulting oil will have a low viscosity index.
Unless otherwise indicated, all boiling points given herein are for a pressure of 1 atmosphere absolute.
The process will now be described with reference to the accompanying drawing which shows by way of example, an overall diagram of a unit operated according to the process of the invention.
Through line 1 is fed a charge formed of a preliminarily deasphalted vacuum distillation residue of a raw petroleum or of a mixture of such a residue with a vacuum distillate.
The deasphalting may be achieved according to any known technique for example, by treatment with of lower paraffinic hydrocarbons, such as propane, butane or a mixture of propane and butane.
This charge is preferably so selected as to have the following characteristics:
initial boiling point higher than 300°C, at least 85 percent of the constituents of the charge having a boiling point higher than 500°C and at least 75 percent of said constituents having a boiling point higher than 525°C;
a viscosity at 98°9 C in the range of from 5 to 100 cst, preferably from 5 to 50 cst;
a viscosity index from 0 to 100;
the following maximum contents:
a. asphaltenes: 0.3 % by weight
b. nitrogen: 0.3 % by weight
c. Conradson carbon: 5 % by weight
The charge preliminarily admixed with fresh hydrogen and conveyed through line 1' is heated in the oven 2 and then conveyed through line 3 to the first hydrotreatment reactor 4. This reactor is also fed with a gas rich in molecular hydrogen introduced through line 5. Of course, hydrogen may be introduced before or after the passage of the charge through the oven 2. In reactor 4, comprising one or more catalytic beds, there is achieved the hydrogenation of the unsaturated compounds of the charge (and particularly of the alkyl aromatic compounds) as well as at least a partial cracking of the naphthenic compounds present in the charge or obtained by hydrogenating said charge in reactor 4.
The operating conditions of reactor 4 are preferably as follows:
L.H.S.V. from 0.1 to 2 liters of liquid charge per liter of catalyst and per hour;
ratio of the flow rate of pure gaseous hydrogen to the flow rate of liquid charge in the range of from 500 to 5,000 liters per liter;
hydrogenating gas (line 5): hydrogen purity higher conveyed through line 13 to an oven 14 and then through line 15 to a first distillation column 16 operated under a pressure close to the atmospheric.
There is thus separated several fractions, for example light hydrocarbons C 1 --C 4 through line 17, a fraction boiling in the gasoline range through line 18 and gas-oil through line 19.
The distillation residue is conveyed through line 20 and after passage through a second oven sent to a second distillation column 22 operated under reduced pressure.
There is thus obtained a heavy gas-oil from line 23 and different oil fractions from lines 24, 25 and 26.
The products issuing from the second distillation column have a content of sulphur impurities lower than 0.1 percent by weight and generally lower than 0.02 percent.
Nitrogen amounts to less than 30 ppm by weight (parts per million of parts of oil).
The Conradson carbon amounts to less than 0.10 percent by weight and generally less than 0.05 percent.
It has been mentioned that the hydrotreatment to which the charge is subjected in the reactor 4 is equivalent to a hydrogenation combined with a cracking; this operation is accompanied with a formation of hydrogen sulphide H 2 S, ammonia NH 3 and very light hydrocarbons, more particularly methane.
These three compounds and more particularly the former two flow essentially from the separator 8 as a mixture with unconsumed hydrogen (a much smaller portion is discharged through duct 12). It is important, when it is desired to recycle the unconsumed hydrogen, to remove completely the than 60 percent (by volume), percentage of CO + CO 2 being at most 2.5 percent. The catalyst may for example contain:
from 2 to 10 percent by weight of cobalt or nickel (expressed as CoO or NiO);
from 10 to 30 percent by weight of molybdenum or tungsten (expressed as MoO 3 or WO 3 );
from 5 to 40 percent by weight of silica and from 22 to 83 percent by weight of alumina (with a preferred ratio by weight of Al 2 O 3 to SiO 2 in the range of from 1.5 to 6).
The outflow from the hydrotreatment reactor is directed, through line 6, to a first gas-liquid separator or flash 8, also called high pressure separator (HP).
The temperature of the mixture flowing through duct 6 has been previously lowered by passage of the mixture through the cooler 7.
In the separator 8 there is recovered, at one end, a liquid phase conveyed through line 9 to a second separator 10, called low pressure separator (LP) and, at the other end, a gaseous mixture rich of hydrogen and flowing through duct 11.
A portion of said gaseous stream is removed, the other being recycled, through line 5, to the hydrotreatment reactor 4. The gas removed from the system may be used for other purposes, for example as combustible gas.
The operation of the separator 10 is similar to that of the first separator except that the pressure is considerably lower (a few kg/cm 2 instead of several tens or even hundreds of kg/cm 2 ).
There is obtained, at the outlet of the second separator, a gaseous mixture removed through line 12 and a liquid phase ammonia and partially the hydrogen sulfide and the very light hydrocarbons. This is achieved by known means.
Various particularly interesting solutions are described in the French patent 1 582 758.
According to a known process, the vacuum distillation residue containing at least 50 percent by weight of constituents boiling above 525°C, withdrawn through duct 27, may either be considered as a base oil and used as such, or may be recycled into the reactor 4.
In the latter case, a mere recycling has many inconveniences: as a matter of fact, the recycled residue being formed of molecules of high molecular weights relatively unaffected by the hydrotreatment, its recycling to the reactor 4 results in a decrease of the catalyst activity and accordingly requires more severe operating conditions for its conversion to lighter products.
The distillate withdrawn from lines 24, 25 and 26 must have relatively constant characteristics. The recycling of the distillation residue through line 27 into the reactor 4, having after a long time the detrimental effect of modifying the catalyst activity, results accordingly in a much more rapid modification of the characteristics of the desired products; in particular it has been observed during the cycle, that the aromatic content suffers substantial changes in the recycled residue and, to a lower degree, in the distillates withdrawn from lines 24, 25 and 26.
It has now been discovered that by passing, during a second step, the distillation residue withdrawn from line 27 through a second reactor containing a catalyst identical to or different from that of the first reactor, it is possible to convert partially or entirely the distillation residue to lighter products while avoiding the above-mentioned drawbacks. This distillation residue, which has been subjected to a substantial conversion during its passage in reactor 4, has a very high paraffinic character and a small content of impurities:
Nitrogen ≤ 100 ppm by weight
Sulphur ≤ 500 ppm by weight
Conradson carbon ≤ 0.1 % by weight
Asphaltenes ≤ 0.05 % by weight
According to the process of the invention, this distillation residue is withdrawn through line 27, heated in the oven 28, optionally after being admixed with fresh hydrogen conveyed through line 27', then sent through line 29 to a second hydrotreatment reactor 30, optionally fed with a gas rich of molecular hydrogen introduced through line 34.
The operating conditions of reactor 30 are preferably as follows:
L.H.S.V. of from 0.1 to 2 liters of liquid charge per liter of catalyst and per hour.
Ratio of the flow rate of pure gaseous hydrogen to the flow rate of liquid charge from 500 to 5,000 liters per liter.
Preferably, the operating conditions in the second reactor 30 are not so severe as those in the first reactor 4, i.e. the L.H.S.V. is higher (1.2 to 2 times higher than the L.H.S.V. in reactor 4), and the temperature lower (for example from 10° to 100°C lower than the temperature in reactor 4); the hydrogen partial pressures being the same in reactors 4 and 30.
Reactor 30 comprises, as well as reactor 4, at least one catalyst bed. The catalyst may, for example, contain:
from 2 to 10 percent by weight of cobalt or nickel (expressed as CoO or NiO)
from 10 to 30 percent by weight of molybdenum or tungsten (expressed as MoO 3 or WO 3 )
from 25 to 75 percent by weight of silica and from 2 to 75 percent by weight of alumina (with a preferred ratio by weight of Al 2 O 3 to SiO 2 in the range of from 0.1 to 1).
Alumina may be amorphous or crystallized; in the latter case, suitably exchanged zeolites may be incorporated thereto (zeolites with a sodium, calcium or lanthanum base by way of example). The zeolitic portion amounts for example to 3 to 15 percent by weight of the total catalyst.
Other catalysts for use in the first or second stage of the process may contain at least one noble metal from group VIII, for example platinum, and at least one carrier such as alumina-silica, chlorinated alumina or fluorinated alumina. Molybdenum or tungsten may also be used, with or without nickel or cobalt, on a halogenated alumina carrier. Other equivalent catalysts, known in the art, may also be used.
The effluent from the hydrotreatment reactor is conveyed through lines 31 and 33 to the first gas-liquid separator 8.
The temperature of the mixture flowing through duct 6 has been previously lowered by passage of the mixture through the cooler 32.
The recycling according to the invention, by passage of the distillation residue to a second reactor, avoids the above mentioned inconveniences. Moreover, this treatment gives a very high flexibility to the process of manufacturing lubricating oils. Particularly, it provides for the possibility, at the desired V.I. level, of maximizing the yields of oily distillates withdrawn from lines 24, 25 and 26 and of changing the distribution of these fractions according to the demand on the markets.
The accompanying drawing is only a simplified diagram of a unit operated according to the invention. Of course, there can be obtained, according to the nature of the charge and the severity of the treatment, a higher or lower number of oil fractions ranging from the "Spindle-oil" type to the "heavy distillate" type (three fractions are shown, by way of example, on the FIGURE). This is also true for the first distillation column 16, particularly with respect to the different fractions obtained (in addition to the residue circulating through line 20).
The different oil fractions obtained from the second distillation are generally subjected to a dewaxing treatment not illustrated on the FIGURE (for example by a mixture methylethylketone-toluene) before being used as base oils to which various additives are generally incorporated.
As hereabove indicated, the FIGURE is only a simplified diagram on which the pumps, compressors, and the like are not shown. The reactor, the distillation columns, the cooler are apparatuses of the type commonly used for this kind of operation.
EXAMPLE
Manufacture of Bases for Multigrade Oils
EXAMPLE 1
The charge is a deasphalted residue having the following composition:
d 4 20 =0.928 S =2.58 % by weight N =800 ppm by weight Conradson carbon =1.80 Viscosity at 98.9°C =35.7 cst Distillation ASTM-1160 =7 % distilled at 500°C 15 % distilled at 525°C 85 % having a boiling point higher than 525°C
the reaction conditions are as follows:
PH 2 =140 kg/cm 2 T =410°C L.H.S.V. =0.7 liter per liter of catalyst and per hour. Hydrogen flow rate (RH 2 ) =1,000 liters per liter of liquid charge
The charge, at the outlet of the first reactor (line 6), has the following composition: (% by weight)
H 2 S+NH 3 2.84 C 1 +C 2 0.42 C 3 +C 4 1.62 C 5 +C 6 2.60 Gasoline 80°-150°C 6.20 Gas-oil 38.42 Oily base 50.00
This base oil, distilled under reduced pressure, gives the following fractions:
100 Neutral: 25% i.e. 12.5% by weight of the initial charge
180 Neutral: 30% i.e. 15 % by weight of the initial charge
400 Neutral: 25 % i.e. 12.5 % by weight of the initial charge
The distillation is discontinued when the temperature (corrected at the atmospheric pressure) reaches 525°C. The remaining distillation residue thus amounts to 20 percent of the base oil, i.e. : 10 percent by weight of the initial charge.
The catalyst used in the first reactor had the following composition:
Composition: Al 2 O 3 56 % (by weight) SiO 2 20 % MoO 3 16 % NiO 8 % Specific surface 250 m 2 /g Total porous volume 55 cc/100g Microporous volume 33 cc/100 g (<0.1μ) Macroporous volume 22 cc/100 g (>0.1μ)
According to the process of the invention the distillation residue is conveyed to a second reactor. The reaction conditions are as follows:
PH 2 =140 kg/cm 2 T =380°C L.H.S.V. =1 liter per liter of catalyst and per hour RH 2 =1,000 liters per liter of liquid charge
The catalyst of the second reactor has the following composition:
Composition: Al 2 O 3 21 % (by weight) SiO 2 55 % WO 3 20 % NiO 4 % Specific surface 250 m 2 /g Total porous volume 55 cc/100 g
The product obtained at the outlet of the second reactor contains 40 percent of light products, which will be later withdrawn from lines 17, 18 and 19 and 60 percent of a base oil. These 60 percent of base oil correspond to 6 percent of the initial charge, since the distillation residue amounted to 10 percent of the initial charge. These 6 % are distributed as follows:
100 Neutral: 2.4 % by weight of the initial charge
180 Neutral: 1.8 % by weight of the initial charge
400 Neutral: 1.8 % by weight of the initial charge
There is no residue.
As a total, there are thus obtained from lines 24, 25 and 26:
12.5+2.4=14.9 % 100 Neutral 15+1.8=16.8 % 180 Neutral 12.5+1.8=14.3 % 400 Neutral
The characteristics of the total base oil (mixture of the products from the first and the second steps) is as follows: viscosity at 98.9°C = 8 cst, V.I. = 125.
The viscosity index (V.I.) has been determined according to the method defined by the Standard ASTM D-567.
The impurity content of this global base oil is very low.
S > 0.01 % (by weight)
N > 1 ppm
Conradson Carbon ≤ 0.02
It has been possible to operate this process over a period of at least 12 months without any catalyst regeneration.
By way of comparison, there has been used a single reactor into which the unconverted residue is recycled. In these conditions, it was necessary to regenerate the catalyst after 2 or 3 months. Moreover, in the latter case, the composition of the base oil is variable during time, because of the adjustments of the catalyst temperature, required for compensating its deactivation.
In this example, all the distillation residue has been converted to light products in the second reactor. But it must be stated that, according to the charge and the required distribution of the oils, the conversion in the second reactor may be either complete or partial. In the latter case, the distillation residue obtained from the initial charge and the distillation residue obtained from the residue treated in the second reactor are withdrawn through line 27 and conveyed together to the second reactor.
EXAMPLE 2
Example 1 is repeated except that the following catalysts are used:
First reactor: Al 2 O 3 60 % (by weight) SiO 2 15 % WO 3 18 % CoO 7 % Second reactor: Al 2 O 3 18 % (by weight) SiO 2 57 % MoO 3 20 % CoO 5 %
The total yield by weight is as follows:
100 Neutral 14.7 % 180 Neutral 16.6 % 400 Neutral 14.5 %