Note: Descriptions are shown in the official language in which they were submitted.
~,.5~
F-2282
COMBINATION PROCESS FOR MAKING IMPROVED
EUBRICATING OILS FROM M MGINAL oRUDES
This invention is concerned with manufacture of hiqh grade
viscous oil products from crude petroleum fractionsO It i.s particularly
directed to the manufacture of high quality lube basestock oils from
crude stocks of high wax content, commonly classified as "wax base" as
compared with the "naphthenic base" crudes. The latter crudes are
relatively lean and straight chain paraffins and yield viscous fractions
which inherently Posses low Pour points. ~ore specifically, the
invention is concerned with improving the viscosity index of lube
basestock oils obtained from marginal lube crudes.
High quality lube basestock oils are conventionally prepared by
refining distillate fractions or the residuum prepared by vacuum
distilling a suitable crude oil from which the lighter portion has been
removed by distillation in an atmospheric tower. Thus, the charge to the
vacuum tower is commonly referred to as a "long residuum" and residuum
from the vacuum tower is distinguished from the starting material by
referring to it as the "short residuum".
The vacuum distillate fractions are upgraded by a sequence of
unit operations, the first of which is solvent extraction with a solvent
selective for aromatic hydrocarbons. This step serves to rem~ve aromatic
hydrocarbons of low viscosity index and provides a raffinate of improved
viscoslty index and quality. Various processes have been used in this
extraction stage, and these emplcy solvents such as furfural, phenol,
sulfur dioxide, and others. The short residuum, because it contains most
of the asphaltenes of the crude oil, is conventionally treated to remove
these asphalt-like constituents prior to solvent extraction to increase
the viscosity index.
The raffinate from the solvent extraction step contains
paraffins which adversely affect the pour point. Thus, the waxy
raffinate, regardless of whether prepared from a distillate fraction or
from the short residuum, must be dewaxed. Various dewaxing procedures
F-2282 -2-
}!;-J havc l~een used, and the art has gone in the direction of treatment with a
solvent such as methyl ethyl ketone/toluene mixtures to renove the wax
and prepare a dewaxed raffinate. The dewaxed raffinate may then be
finished by any number of sorption or catalytic processes to improve
color and oxidation stability.
The quality of the lube basestock oil prePared by the sequence
of operations outlined above depends on the particular crude chosen as
well as the severity of treatment for each of the treatment steps. For
example, crudes such as Arab Heavy have been found previously to be
unsatisfactory crudes for making lubes having a viscosity index (V. I.) of
100 using conventional furfural extraction and solvent dewaxing
processing steps and are thus characterized as giving marginal quality
lubricating oils. Additionally, the yield of high quality lube basestock
oil also depends on these factors, and as a rule, the higher quality
1 S sought, the less the yield. In general, naphthenic crudes are favored
because less loss is encountered, particularly in the dewaxing step. In
many cases, however, waxy crudes are more readily available, and it would
be desirable to provide a process for preparing high quality lube
basestock oils in good yields from such waxy crude oils to broaden the
crude sources for making lubes.
In recent years techniques have become available for catalytic
dewaxing the petroleum stocks. A process of that nature developed by
British Petroleum is described in the Oil and Gas Journal dated January
6, 1975, at pages 69-73. See also U. S. Patent No. 3,668,113.
In U. S. Patent No. Reissue 28,398 is described a process for
catalytic dewaxing with a catalyst comprising zeolite ZSM-5. Such
process combined with catalytic hydrofinishing is described in U. S.
Patent ~b. 3,894,938 for reducing the pour point of a sulfur and
nitrogen-containing gas oil boiling within the range of 400-900F
(204~820c).
In U. S. Patent No. 3,979,279, a stabili~ed lubricating oil
stock resistant to oxidation and sludge formation upon exposure to a
highly oxidative environment is formed by contacting a high viscosity
lubricating oil stock with hydrogen in the presence of a catalyst of low
acidity comprised of a platinum- group metal on a solid refractory
inorganic oxide support.
5~
F-2282 _3_
In U. SO Patent Nb. 3,530,061, a stabilized lube oil product
obtained by hydrocracking is produced by contacting a lube oil product
before or after dewaxing with a catalyst having
hydrogenation-dehydrogenation activity and hydrogen at a pressure in the
range from atmospheric up to about 100 psig (791 kPa) under conditions of
temperature in the range of ~00F (204C) to about 800F (427C).
A two-stage process for preparing a high quality lube basestock
oil is disclosed in U. S. Patent No. 4,181,598 in which a raffinate is
mixed with hydrogen and the mixture contacted with a dewaxing catalyst
comprising a ZSM-5 type catalyst to convert the wax contained in the
raffinate to low boiling hydrocarbons and subsequently, contacting the
dewaxed raffinate in the presence of hydrogen at a temperature of
425-600F (218-316C) with a hydrotreating catalyst comprising a
hydrogenation component on a non-acid support such as cobalt-molybdate or
nickel-molybdate on alumina. Hydrotreating the dewaxed raffinate is
limited to saturate olefins and reduce product color without causing
appreciable desulfurization.
It has been found in a hydrofinishing optimization study that at
higher temperatures above 500F (260C) oxidation stability declined but
that the viscosity index could be increased several numbers.
It is an object of this invention to provide a process for
increasing the viscosity index of a dewaxed lube basestock oil obtained
from marginal crudes in order to broaden the crude sources for making
lubes.
Pnother object of the invention is to produce light and air
stable lubricating oils with V.I. in the order of 100 from marginal crude
feedstocks. Other objects will be evident to those skilled in the art
upon reading the entire contents of this specification, including the
claims thereof.
The present invention provides a process for preparing a high
quality lube basestock oil from waxy crude oil. Cuch a process comprises
(A) extracting a waxy crude oil distillate fraction that boils within the
range of from 316C to 593C (600F to 1100F), or a deasphalted short
residuum fraction of such a waxy crude oil, with an aromatic hydrocarbon
solvent in order to yield a wax-containing raffinate from which
F-2282 -4~
undesirable compounds have been removed; (8)mixing the wax-containing
raffinate with hydrogen and contacting this mixture under particular
temperature conditions with a particular type of dewaxing catalyst to
thereby convert wax contained in the raffinate to lower boiling
hydrocarbons; and (C) cascading this dewaxed raffinate to a hydrotreating
zone wherein the dewaxed raffinate is contacted in the presence of
hydrogen with a particular type of hydrotreating catalyst under
particular reaction conditions to hydrotreat the dewaxed raffinate to
substantially complete desulfurization but to avoid substantial
hydrooenation of aromatic compounds in the raffinate. Such a procedure
yields a lube basestock oil having a viscosity index of approximately 100.
The dewaxing catalyst emDloyed in the dewaxing step is a
catalyst comprising an aluminosilicate zeolite having a silica/alumina
ratio of at least 12 and a constraint index of from 1 to 12. Temperature
in the dewaxing step ranges from 260C to 357C (5ûûF to 675F).
The hydrotreating catalyst employed in the hydrotreating zone
comprises a strong hydrogenation component on a non-acidic support.
Conditions in the hydrotreating zone include a hydrogen Partial pressure
of from about 6996 kPa to 20786 kpa (lOOû psig to 3000 psig), a
temperature of from about 260C to 357C (500F to 675F) and a liquid
hourly space velocity of from about 0.1 to 2Ø
The present invention is thus based on the discovery that the
obtainable light and air stability and high viscosity index of the
resulting Product coincides with essentially complete desulfurization of
25 this dewaxed lube product. Light and air stable lubricating oils with a
viscosity index in the order of 100 can thus be produced from marginal
crude feedstocks.
The features of the present invention can be illustrated by
Figures 1-5 of the drawings discussed more fully hereinafter.
Figure 1 is a qraph of experimental data illustrating lube yield
after hydrotreating versus viscosity index of the lube product.
Figure 2 is a graph of experimental data illustrating sulfur
content versus viscosity index of the hydrotreated lube product.
Fiqure 3 is a graph of experimental data illustrating hydrogen
consumption versus viscosity index of the hydrotreated lube.
F-2282 ~5
Figure 4 is a graph of experimental data illustrating pour point
versus viscosity index of the hydrotreated lube.
Figure 5 is a graph of experimental data illustrating viscosity
versus viscosity index.
The wax base crudes (sometimes called "paraffin base") from
which the chargestock is derived by distillation constitute a
well-recognized class of crude petroleums. Many scales have been devised
for classification of crude, some of which are described in chapter VII,
Evaluation of Oil Stocks of "Petroleum Refinery Engineering," W. L.
Nelson, McGraw Hill, 1941. A convenient scale identified by Nelson at
paqe 69 involves determination of the cloud point of the U.S. Rureau of
Mines (key fraction #2) which boils between 527F (275C) and 572F
(300C) at 40 mm (5333 Pa) pressure. If the cloud point of this fraction
is above 5F (-15C), the crude is considered to be wax base.
In practice of the present invention, a suitable chargestock
such as a propane deasphalted short residuum fraction or a fraction
having an initial boiling point of at least about 450F (232C), and
preferably at least about 600F (316C), and a final boiling point less
than about 1100F (593C) is prepared by distillation of such wax base
2~ crude. 9uch fraction can than be solvent refined by counter current
extraction with at least an equal volume (100 volume percent) of a
selective solvent such as furfural. It is preferred to use about 1.5-3.0
volumes of solvent Per volume of oil. The solvent, e.g., furfural,
raffinate can be subjected to catalytic dewaxing by mixlng with hydrogen
and contacting at 500-675F (260-357C) with a catalyst containing a
hydrogenation metal and zeolite ZSM-5 or other related silicate zeolites
having a silica/alumlna ratio of at least 12 and a Constraint Index of
1-12 using a liquid hourly space velocity (LHSV) of 0.1-2.0 volumes of
charge oil per volume of catalyst per hour. The preferred space velocity
is 0.5-1.0 LHSV.
The effluent of catalytic dewaxing can then be cascaded into a
hydrotreater containing, as catalyst, a strong hydrogenation component on
a non-acid support, such as supported nickel- tungsten or platinum on
alumina. Typically, the hydrotreater operates at temperatures of
F-2282 -6-
500-675F (260-357C3 and at elevated pressures within the range of
1000-3000 psiq (6996-20786 kPa), preferably 1200-2500 psig (8375-17338
kPa) and a space velocity like that of the catalytic dewaxing reactor.
The catalytic dewaxing reaction can be carried out at hydrogen
partial pressures of 150-3000 psia (1034-20684 kPa), at the reactor
inlet, and preferably at 250-1500 psia (1724-10342 kPa). Dewaxing and
hydrotreating operate at 500 to 5000 standard cubic feet of hydrogen per
barrel of feed (SCF/bbl)(89 to 890 nl of H2/1 of feed), preferably
1500-2500 SCF/bbl (267-445 nl/l). It is preferred to dewax at the same
pressure as the hydrotreat stage.
At the conditions utilized in the hydrotreater, the dewaxed
effluent is converted over the strong hydrogenating catalyst to a
material having a viscosity index (V.I.) of approximately 100, e.g., from
95 to 105. The viscosity index is an empirical number indicating the
effect of change of temperature on the viscosity of an oil. A low
viscosity index signifies a relatively large change of viscosity with
temperature, and vice versa. By means of the viscosity in~ex function,
the steepness of the viscosity-temperature curve of the sample is
interpolated between that of a Pennsylvania Oil (denoted as 100 VI) and
that of a Texas Coastal Oil (denoted O VI), both of which reference oils
have the same viscosity as the sample at 210F (99C).
The high viscosity index of the lube obtained coincides with
substantially complete desulfurization. While further cracking increases
V.I., loss of yield increases and both light and air stability suffer.
In some instances, it may be desirable to partially dewax the
chargestock, i.e., solvent-extracted raffinate, by conventional solvent
dewaxing techniques, say to a pour point from 10F (-12C) to about 50F
(10C). The higher melting point waxes so removed are those of higher
market value than the waxes removed in conventionally taking the product
to a still lower pour point below 10F (-12C).
The cracked (and hydrogenated) fragments from cracking wax
molecules in the catalytic dewaxer will have adverse effects on flash and
fire points of the dewaxed raffinate product and are therefore removed by
distillation of the product to flash and fire point specifications.
F-2282 ~7~
The catalyst employed in the catalytic dewaxing reaction zone
and the temperature in that reaction zone are important to success in
obtaining good yields and very low pour point product. The strong
hydrotreater catalyst may be any of the catalysts commercially available
for that purpose but the temperature should be held within narrow limits
for the desired cracking (desulfurization).
The solvent extraction technique is well understood in the art
and needs no detailed review here. The severity of extraction is
adjusted to composition of the chargestock to meet specifications for the
particular lube basestock and the contemplated end-use; this severity
will be determined in practice of this invention in accordance with well
established practices.
The catalytic dewaxing step can be conducted at temperatures of
5û0-675F (260-357~C). At temperatures above about 675F ~357C),
bromine number of the product generally increases significantly and the
oxidation stability decreases.
The dewaxing catalyst is preferably a composite of hydrogenation
metal, preferably a metal of Group VIII of the Periodic Table, associated
with the acid form of an aluminosilicate zeolite having a silica/alumina
ratio of at least about 12, and a constrained access to the
intracrystalline free space as measured by having a Constraint Index of
from about 1 to 12.
Zeolite materials of silica/alumina molar ratio greater than 12
and Constraint Index of 1 to 12 are used in the dewaxing catalyst
employed in the present invention. Such zeolites, also known as ZSM-5
type zeolites, are well known. This use as dewaxing catalysts has, for
example been described in U.S. Patent 4,358,363.
Crystalline zeolites of the type useful in the dewaxing
catalysts of the present invention include ZSM-5, ZSM-ll, ZSM-12, ZSM-23,
ZSM-35, ZSM-38, ZSM /l8 and zeolite beta, with ZSM-5 being particularly
preferred.
ZSM-5 is described in greater detail in U.S. Patent Nos.
3,702,886 and RE 29,948, which patents provide the X-ray diffraction
pattern of the therein disclosed ZSM-5.
F-2282 -8-
ZSM-ll is described in U.S. Patent Nb. 3,709,979, which
discloses in particular the X-ray diffraction pattern of ZSM-ll.
ZSM-12 is described in U.S. Patent No. 3,832,449, which
discloses in particular the X-ray diffraction pattern of ZSM-12.
ZSM-23 is described in U.S. Patent No. 4,076,842, which
discloses in particular the X-ray diffraction pattern of 25M-23.
ZSM-35 is described in U.S. Patent Nb. 4,016,245, which
discloses in particular the X-ray diffraction pattern of ZSM-35.
ZSM-38 is described in U.S. Patent Nb. 4,046,859, which
discloses in particular the X-ray diffraction pattern of ZSM-38.
ZSM-48 is described in U.S. Patent No. 4,375,573 and European
Patent Publication EP-A-0015132, which discloses in particular the X-ray
diffraotion pattern of ZSM-48.
Zeolite beta is descrlbed in greater detail in U.S. Patent Nos.
3,308,069 and RE 28,341, which patents disclose in particular the X-ray
diffraction Pattern of zeolite beta.
A ZSM-5 type zeolite also useful herein includes the highly
siliceous ZSM-5 described in U.S. Patent 4,067,724 and referred to in
that patent as "silicalite."
The sPecific zeolites described, when prepared in the presence
of organic cations, are catalytically inactive, possibly because the
intracrystalline free space is occuPied by organic cations from the
forming solution. They may be activated by heating in an inert
atmosphere at 1000F (538C) for 1 hour, for example, followed by base
exchange with ammonium salts followed by calcination at 1000F (538C) in
air. The presence of organic cations in the forming solution may not be
absolutely essential to the formation of this type zeolite; ho~ever, the
presence of these cations does appear to favor the formation of this
special type of zeolite. More generally, it is desirable to activate
this tyDe catalyst by base exchange with ammonium salts followed by
calcination in air at about lOû0F (538C) for from about 15 minutes to
about 24 hours.
Thus when synthesized in the alkali metal form, the zeolite is
conveniently converted to the hydrogen form, generally bey intermediate
formation of the ammonium form as a result of ammonium form to yield the
F-2282 -9-
hydrogen form. In addition to the hydrogen form, other forms of the
zeolite wherein the original alkali metal has been reduced to less than
about 1.5 percent by weiqht may be used. In this manner, the original
alkali metal of the zeolite may be replaced by ion exchange with other
suitable ions of Groups IB to VIII of the Periodic Table9 including, by
way of example, nickel, copper, zinc, palladium, calcium or rare earth
metals.
In Practicing the catalytic dewaxing step of the present
invention, it may be desirable to incorporate the above-described
crystalline aluminosilicate zeolite in another material resistant to the
temperature and other conditions employed in the process. Such matrix
materials include synthetic or naturally occurring substances as well as
inorganic materials such as clay, silica and/or metal oxides. The latter
may be either naturally occurring or in the form of gelatinous
precipitates or gels including mixtures of silica and metal oxides.
Naturally occurring clays which can be composited with the zeolite
include those of the montmorillonite and kaolin families, which families
include the sub-bentonites and the kaolins commonly known as Dixie,
Mc~amee-Georgia and Florida clays or others in which the main mineral
constituent is halloysite, kaolinite, dickite, nacrite or anauxite. Such
clays can be used in the raw state as originally mined or initially
subjected to calcination, acid treatment or chemical modification.
In addition to the foregoing materials, the zeolites employed
herein may be composited with a porous matrix material, such as alumina,
silica-alumina, silica-magnesia, silica- zirconia, silica-thoria,
silica-berylia, silica-titania as well as ternary compositions, such as
silica-alumina-thoria, silica- alumina-magnesia and
silica-magnesia-zirconia. The matrix may be in the form of a cogel. The
relative proportions of zeolite component and matrix may vary widely with
the zeolite content ranging from between about 1 to about 99 percent by
weight and more usually in the range of about 5 to about 80 percent by
weight of the composite.
In the process of this invention, the total effluent of the
catalytic dewaxing step, including the hydrogen, is cascaded into a
hydrotreatinq reactor of the type now generally employed for finishing of
F-2282 -lO-
lubricating oil stocks. In this "cascade" mode of oPeration, the
hydrotreater is sized to handle the total dewaxer effluent. Plthough
some modification of the cascade oPeration is contemplated, such as
interstage recovery of gasoline boiling range by-Product~ it is to be
understood that such modification contemplates no substantial
interruption or substantial delay in passing the dewaxed raffinate to the
hydrotreater. Thus, "cascading", as used herein, means passing the
dewaxed raffinate plus hydrogen to hydrotreating without storage of the
dewaxer effluent.
Any of the known hydrotreating catalysts consisting of a strong
hydrogenation component on a non-acidic support may be employed in the
hydrotreating step. Such catalysts include, for example, nickel-tungsten
on silica-alumina or platinum on alumina. Here again, temperature
control is required for production of high quality products having the
desired desulfurization and thus high V.I as well as light and air
stability.
The effluent of the hydrotreater is topped by distillation,
i.e., the most volatile components are removed, to meet flash and fire
point sPecifications.
The following ExamPles are given as illustrative of this
invention and are not to be construed as limiting thereon except as
defined by the claims. In the Examples, all parts are given by weight
unless specified otherwise.
Example l
The crude source of this Example is Arab Heavy. Distillation of
the crude yielded 9.1% volume vacuum distillate, above a 27.3% volume
vacuum resid. The vacuum distillate had the properties as set forth in
Table l.
~5~
F-2282 -11-
T~BLE 1
Properties of Distillate
Gravity, API 18.4
Specific 0.944
Distillation
IBP* 615F (324C)
5% 797F (425C)
843F (451C)
875F (468C)
895F (479C)
918F (492C)
960F (516C)
983F (528C)
Composition
Paraffins 16% by weight
Naphthenes 23% by weight
Aromatics 61% by weight
*Initial Boiling Point
The vacuum distillate was furfural extracted at 195F using a
solvent/oil ration of 200. The yield of raffinate was 53.3 wt.% and had
the following properties:
Gravity, API 27.4
Specific 0.8905
KV* at 100C, centistokes 9.58
25Refractive Index at 70C 1.4704
*Kinematic Viscosity
F-2282 -12-
The raffinate obtained above was processed under dewaxing
conditions to a pour point of ~25F (-4C) using a dual catalyst bed of
Ni/ZSM-5 followed by Co/Mo/Al. The dewaxing conditions are as follows:
Pressure, Psiq 400 (2859 kPa)
LHSV 1.0 hr 1
H2 Circ., SCF/bbl 2500 (445 nl/l)
Temp., F 500-675 (288-357C)(Ni/ZSM-5)
515 (268C)(Co/Mo/Al)
Yield o~ the dewaxed oil was 84.7 wt.%. The Properties of the
product are set forth in Table 2.
TABLE 2
Properties of Dewaxed Lube
Gravity, API 26.0
Specific 0.8984
Pour Point, E +25 (-4C)
KV* at 40C, cs 116.1
100C, cs 11.47
SUS** at 100F, Sec. 611
210F, Sec. 65.7
Viscosity Index 82.5
Sulfur, wt.% 1.19
Wt.% S Compounds 17***
Boiling Range, F
1% 617 ~325C)
749 (398C)
790 (421C)
849 (454C)
884 (473C)
916 (491~C)
go 961 (516C)
984 (529C)
*Kinematic Viscosity
**Saybolt Universal Seconds
***Assuming one S atom/molecule
The viscosity index of the oil is too low to be of commercial
value as is that obtained by conventional solvent dewaxing of the
raffinate (about 90). In addition, the viscosity of the catalytically
dewaxed oil is undesirably high.
F-2282 -13-
Example 2
The catalytically dewaxed oil of ~xample 1 having the properties
set forth in TAble 2 was hydrotreated over a commercial catalyst
Ni/W/Ti/SiA1 (ICR-1061M from Chevron). The catalyst samples contained
19.7 wt.% W, 6.5 wt.% Ni, 4.5 wt.% Ti, 0.04 wt.% CoO, 0.03 wt.% MbO3,
and the remainder is silica- alumina. The catalyst was sulfided before
use. Conditions of the hydrotreating were as follows:
Pressure, psig 1500 (10443 kPa)
LHSV, hr 1 0.5
H2 Circ., SCF/bbl 5000 (890 nl/l)
Temp., F 525-650 (274-343C)
Hydrogen circulation, pressure and LH5V were kept constant while
the temperature was varied. Detailed run data using ICR-106~M is set
forth in Table 3.
~0 N _ ~ N ~ ~ N N
N ~ ~ V ~ U~ 0 3 1~\ N 1~ 0~ ` O 1 N
._ ~
~o N N ~ ~ O O O O U~ a~--oO ~ ~ O ~0 ~ CO ~ ~ N ~ , O ~1 0~ "~ N `.D N U~
N ~ ~3 N o 0 N N ~
N N V N ~ O N N C0~ ~ 8 ~ ~ o0~ o _~ N ~O _ ~1 o U~ N
U~ ~ 1~ O N t~ 0 ~ ~a 1` u~\ N 0 N ~ ~
3 ~ t?~ N CO 0 0 0 0 0 N ~ 1 0 0 0 O U\ ~ O u~ 0 0--~ 0 0 ~-1 it'\ 0 1~ ~ 11~ ~D N 11~ G
y V O ~N N N+ ~ _ ~0 _ 5~ ~D 0 ~o ~ 0 0 ~0 o~ ~ o
8 _ N N Y
u~ 0 0 u~ _ _1 0 ~0 0 N _ Y~ O 1`
> 1'~ ~ N O--o~ O O ~o N N O _ ~ i ~ ~D 0 --I ~C ~ ~i ~0 O o ~
~ It~ N C)
O ~ N O ~ N O CO O O O ~ .--1 0 0 0 0 O O ~0 ~ ~ O _ ~ O 01~ 1`--0 ~ j~ 0 ~ ~r
-- ~ ~ .~ U~ N r~ O V V O` _ U~ N N+ 0 1~ o, --U\ ~ ~ 0~ 0~ ~ 8
I ~-- Q ~ O
~¦ - rOD ~ O (~ 0 U~ 1` 0. _ _ J~ N ~r 1` ~0 ~ 0N ~o ~ ~ _
2Iv c~ Z _ -- ,,~ ~N ~\ O C C 0 r0~ o N ~ N ~o 0 ~ 0 r~ ~t g`~ O N ~ 0 ~ o~ o
~ ~ a)
~ o _~ ~ N 0 N N 1~ 0 ,~,
r 0 ~ O uN~ O _ ~ D 0 _~ N 1~ - ~
~ n 3 ~~
~ v c ~ o
16 0 0 ~ I 01` -- ~ o ~ O
N N _ _ ~ _ _ ~O 0 U~ _ ~r ~ g~ 0 _ 0 -Q
E ~ 3
tn x >~a~ on o o >
.n C~ ~ ,v~ ~ ~~ _ _ o
C ~ . X
E D ~ C _ _ C~ Q O r V (.) O C ~ & cr
r.~ m u n~ u n ~ c c) ~ . ~ ~ CL c r~
v Q' c ~ ~ ~* o ~ ~o ^ 5~ ,C (0-1 0 oO O O O ~ 3 ^ Q' O
zn O ~ .,~ 3- ~,~N c ~ c 3 ~ o o o o N ^ G C ;?~ e ~ 3P ~ a~ 2`~? ~
~ ~ ~ ~ + ~ I O ~ vO ~o~ ~ ~ O > > > ~ ,Q ~n ~ ~
C E ~ C C ~ ~ ~ 1--~) C` t~ ~ ~ Y `' ~ ~ > ~ Q~
~~7 [~ Z8ZZ-~
F-2282 -15-
Figures 1-5 are obtained from the data set forth in Table 3.
Referring to Figure 1, at 100 V.I., lube yield is about 80 wt.%,
and at 110 V.I. yield drops sharply to 55 wt.%. The V.I. at lQ0 matches
that obtained from premium lube stocks, such as Arab Light using
conventional solvent dewaxing technology.
Referring to Fiqure 2, it can be seen that the 80~ lube yield
giving 100 V.I. corresponds to complete removal of the 17 wt.% sulfur
compounds calculated to be in the chargestock. Thus, it appears the
sulfur compounds in Arab Heavy have very low V.I., and their selective
removal as accomplished by hydrotreating in this Example results in a
fortuitous increase in V.I. to the desired 100 level. Conversion
(hydrocracking) beyond this point gains some further V.I., but at a
higher yield loss (Figure 1) and, as will be discussed later, loss of
liqht and air stability.
Lube oil composition studies indicate that the major reaction
occurring over the hydrotreating catalyst used herein as V.I. is
increased from the 82.5 of the feedstock to 99.4 is desulfurization. The
paraffins and naphthene contents increase in proportion to the removal of
the 17% aromatic sulfur compounds calculated to be in the charge as shown
in Table 4 below.
f-2282 -16-
TABLE 4
Lube Composition Studies
Charge
82.5 V.I. 90.9 V.I. 99.4 V.I.
100 wt.% 91.6 wt.% 78.9 wt.96
Composition, wt.%Found Found Calc(l) Found Calc(2)
Paraffins 14.2 15.4 15.5 20.2 17.9
Mono Naphthenes 12.8 14.5 14.0 19.3 16.1
Poly r~laphthenes32.5 38.3 35.5 37.1 40.9
Aromatics (including
S comPounds) 40.5 31.8 35.0 23.4 25.1
100.0 100.0 100.0100.0 100.0
(1) Charqe ~ 0.916 for Paraffins and naphthenes, aromatics by
difference.
15 (2) Charge; 0.789 for paraffins and naphthenes, aromatics by
difference.
If aromatics were being hydrogenated, the naphthene contents
found would be higher than those calculated. At the 99.4 V.I. level
essentially all the sulfur co~pounds have disappeared, so that further
20 V. Io increase cannot be explained by desulfurization. The high hydrogen
consumption at 111 V. I. (740 SCF/bbl (132 nl/l), Figure 3) indicates that
aromatic hydrogenation does become significant after desulfurization is
- complete.
As shown in Figure ~, hydrogen consumption to make 100 V. I. oil
25 over catalyst ICR-106TM is about 280 SCF/bbl (50 nl/l). Hydrogen
consumption increases drastically as viscosity index increases to 110.
~,, ,r~" ~
F-2282 -17-
From Figure 4, it can be seen that the pour point remains
substantially the same during hydrotreating within an experimental error
of the charge, +25F + 5f (-4C + 2.8C).
As shown in Figure 5, viscosities in SUS at 110F (38C) and
21ûF (99C) decreases with increasing V.I. The lûO V.I. oil, however,
is still high in the SAE 2û viscosity index range of 45-58 seconds at
210F (9~C).
Example 3
Portions of the oils obtained from hydrotreating were exposed to
1~ air and sunlight for a period of three weeks. The 112 V.I. oil exhibited
stability characteristics of hydrocracked oils, i.e. haze after 2 days
exposure, and formation of suspended brown ~loc followed by precipitation
after 4 days. rhe oils with lûO V.I. and less however, remain clear for
2-3 weeks which is generally considered sufficient to establish
staoility. However, haze and some solid matter do form from prolonged
exposure. The results are shown in Table 5.
TACLE 5
Air and Li~ht Stability
Product V.I. 91 99 100 112
2~ Charge -3 -2 -7 -8
Days to Haze 50+ 23 33 14 2
Days to Sludge 50+ 50+ 47 18 4
mm Sludge* at 10 days 0 0 0 0 <1
mm Sludge* at 50 days 0 0 <1 1 <1
at 30 days
* Cepth at bottom of vial
The haze in the 91 V.I. sample was a very fine divided white
material as opposed to the reddish-brown coarse floc characteristic of
hydrocracked oils. Warming of the oil by direct sunlight reduced the
F-2282 -18-
haze considerabiy. ~n alcohol thermometer taped to the window read 115F
(46C) while the room temperature was 78F (26C). Late in the day, as
the oil cooled, the haze returned. This reversibility of the haze would
fit wax formation. The charge oil containing all its aromatic sulfur
compounds does not form haze, which suggests that the addition of sulfur
compounds normally used in the additive package could inhibit the haze.
