Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
lZ~
F-2834 - 1 -
PROCESS FOR MAKING IMPROVED
LUBRICATING OILS FROM HEAVY FEEDSTOCK
This invention is concerned with manufacture of high grade
viscous oil products from crude petroleum fractions or other
hydrocarbon materials. It is particularly directed to the
manufacture of high quality lube basestock oils from crude stocks of
high boiling point as opposed to using so-called light stocks. The
latter crudes have lower boiling points and for reasons which are
not fully understood, do not show any advantage in the novel process
of this invention over commercially practiced technology. More
specifically, the invention is concerned with dewaxing of lube
basestock oils having an initial boiling point higher than 371C
(700F) and a 50 volume percent boiling point of at least 482C
(900F).
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
remove aromatic hydrocarbons of low viscosity index and provides a
raffinate of improved viscosity index and quality. Various
processes have been used in this extraction stage, and these employ
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.
*
~Z~8'~3
F-2834 - 2 -
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 have been used, and the art has gone in the direction of
treatment with a solvent such as methyl ethyl ketone/toluene
mixtures to remove 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.
In recent years techniques have become available for
catalytic dewaxing the petroleum stocks. A process of that nature
developed by Britis~ Petroleum is described in the Oil and Gas
Journal dated January 6, 1975, at pages 69-73. See, also, United
States Patent No. 3,668,113.
In United States 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 United States Patent No. 3,894,938 for reducing the
pour point of a sulfur and nitrogen-containing gas oil boiling
within the range of 204 to 482C (400 to 900F).
United States Patent No. 3,755,145 discloses a process for
preparing lube oil having low pour points involving using a catalyst
mixture comprising hydrogenation components, a conventional cracking
catalyst and a crystalline aluminosilicate zeolite of the ZSM-5
type. At Column 8 there is specifically disclosed the use of an
extrudate having a l/16th of an inch diameter.
United States Patent No. 3,894,938 discloses the catalytic
dewaxing and desulfurization of gas oils with a ZSM-5 zeolite
containing a hydrogenation component. At Column 3 it is
specifically pointed out that the ZSM-5 can be incorporated into a
matrix and that the catalyst particles can be sized between 0.8 and
3.2 mm (1/32nd and 1/8th of an inch).
F-2834
United States 3,846,337 discloses silica-bound silicate
particles of improved strength within the range of 0.8 to 3.2 mm
(1/32 to about 1/8 inch) average extrudate diameter and their use in
various catalysts reactions.
These processes did not provide any guidance as to how to
achieve a more stable operation when processing heavy lubricating
oil stocks, such as bright stock.
We discovered that more efficient dewaxing of these heavy
stocks could be achieved using a special dewaxing catalyst with
certain physical properties.
Accordingly, the present invention provides a process for
dewaxing a petroleum feedstock having an initial boiling point of at
least 371C (700F) and a 50 volume percent boiling point of at
least 482C (900F) wherein said hydrocarbon is contacted in the
presence of added hydrogen at a temperature of 232 to 427C (450 to
800F) with a dewaxing catalyst comprising aluminosilicate zeolite
having a silica-to-alumina ratio of greater than 12 and a Constraint
Index of 1 to about 12 and wherein said aluminosilicate zeolite is
composited with an inorganic oxide binder and characterized by using
a catalyst composite having a maximum diffusion distance of less
than 0.6 mm (0.025 inch).
Figure 1 is a graph of actual experimental data
illustrating the temperature requirements to catalytically dewax a
lube stock whose boiling range lies outside the scope o~ the present
invention, over a prior art catalyst.
Figure 2 is a graph of actual experimental data
illustrating the temperature requirements to catalytically dewax
with the invention catalyst a lube stock whose boiling range lies
outside the scope of the invention.
Figure 3 is a graph of actual experimental data showing the
effect of treating a heavy neutral feedstock with an extruded
catalyst having a particle diameter of 0.8 mm (0.03125 inch)
compared to a prior art catalyst.
33
F-2834 ~ 4
Figure 4 is a graph of actual experimental data showing the
dewaxing of a heavy neutral feedstock on the subsequent cycle to
Figure 3 comparing the same reference and invention catalysts.
Figure 5 shows experimental data on the dewaxing of a
bright stock using the same reference and invention catalysts shown
in Figures 3 and 4.
Figure 6 shows experimental data on the dewaxing of bright
stock comparing extruded catalyst and finely crushed catalyst.
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 classificaton of crude, some of which are described in
Chapter VII, ~Evaluation of Oil Stocks of Petroleum Refinery
Engineering, by ~. L. Nelson, McGraw Hill, 1941. A convenient scale
identified by Nelson at page 69 involves determination of the cloud
point of the Bureau of Mines (key fraction #2) which boils between
275C (527F) and 3ûOC (572F) at 40 mm pressure. If the cloud
point of this fraction is above -15C (5F), the crude is considered
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 468C
(875F), and preferably at least 482C (900F.) and a final boiling
point greater than 649C (1200F) is prepared by distillation of
such wax base crude. Such fraction can then be solvent refined by
counter current extraction with at least an equal volume (100 volume
percent) of a selective solvent such a furfural. It is preferred to
use about 1.5-3.0 volumes of solvent per volume of oil. ~he
furfural raffinate has an initial boiling point of greater than
371C (700F) and a 50 volume percent boiling point of at least
482C (900F). It is then subjected to catalytic dewaxing by mixing
in hydrogen and contacting at 232 to 427C (450 to 8û0F),
preferably at 260 to 371C (500 to 700F), with a catalyst
containing a hydrogenation metal, an inorganic oxide binder and
T5 3
F-2834 _ 5 _
zeolite ZSM-5 or other related silicate zeolites having a
silica-to-alumina ratio of at least 12 and a Constraint Index of
1-12 and 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 catalyst is extruded or otherwise shaped so as to have
a maximum diffusion distance of less than 0.6 mm (0.025 inch).
The catalytic dewaxing reaction is preferably carried out
at hydrogen partial pressures of 1,100 to 21,000 kPa (150 to 3000
psig), at the reactor inlet, and preferably at 1,800 to 10,400 kPa
(250 to 1500 psig). Dewaxing operates at a hydrogen circulation of
90 to 900 volumes of liquid at standard conditions per volume of
H2 at standard conditions, v/v,(500 to 5000 standard cubic feet
per barrel of feed (SCFB)I preferably 270 to 530 v/v (1500 to 3000
SCFB).
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 is conducted at 232 to 427C
(450 to 800F). However, at temperatures above 357C (675F),
bromine number of the product generally increases and the oxidation
stability decreases.
The dewaxing catalyst is a composite of hydrogenation
metal, such as nickel, cobalt, molybdenum, chromium, tungsten,
palladium, platinum or compositions thereof associated with the acid
form of a novel class of aluminosilicate zeolite having a
silica-to_alumina ratio of at least about 12, and a constrained
access to the intracrystalline free space, as more fully described
hereinbelow.
F-2834 - 6 -
An important characteristic of the crystal structure of
this class of zeolites is that it provides constrained access to and
egress from the intracrystalline free space by virtue of having a
pore dimension greater than about 5 Angstroms and pore windows of
about a size such as would be provided by lû-membered rings of
oxygen atoms. It is to be understood, of course, that these rings
are tnose formed by the regular disposition of the tetrahedra making
up the anionic framework of the crystalline aluminosilicate, the
oxygen atoms themselves being bonded to the silicon or aluminum
atoms at the centers of the tetrahedra. Briefly, the preferred type
zeolites useful in this invention possesses, in combination: a
silica-to-alumina mole ratio of at least about 12; and a structure
providing constrained access to the crystalline free space.
The silica-to-alumina ratio referred to may be determined
by conventional analysis. This ratio is meant to represent, as
closely as possible, the ratio in the rigid anionic framework of the
zeolite crystal and to exclude aluminum in the binder or in cationic
or other form within the channels. Although zeolites with a
silica-to-alumina ratio of at least 12 are useful, it is preferred
to use zeolites having higher ratios of at least 30. Such zeolites,
after activation acquire an intracrystalline sorption capacity for
normal hexane which is greater than that for water, i.e., they
exhibit "hydrophobic" properties. It is believed that this
hydrophobic characteristic is advantageous in the present invention.
Rather than attempt to judge from crystal structure whether
or not a zeolite possesses the necessary constrained access, a
simple determination of the Constraint Index may be made by passing
continuously a mixture of an equal weight of normal hexane and
3-methylpentane over a small sample, approximately 1 gram or less,
of catalyst at atmospheric pressure according to the following
procedure. A sample of the zeolite, in the form of pellets or
extrudates, is crushed to a particle size about that of coarse sand
and mounted in a glass tube. Prior to testing, the zeolite is
treated with a stream of air at 538C (lOOO~F) for at least 15
F-2834 _ 7 _
minutes. The zeolite is then flushed with helium and the
temperature adjusted to sive an overall conversion between 10% and
60 percent. The mixture of hydrocarbons is passed at 1 liquid
hourly space velocity (LHSV) (i.e., 1 volume of liquid hydrocarbon
per volume of zeolite per hour) over the zeolite with a helium
dilution to give a helium to total hydrocarbon mole ratio of 4 to
1. After 20 minutes on stream, a sample of the effluent is taken
and analyzed, most conveniently by gas chromatography, to determine
the fraction remaining unchanged for each of the two hydrocarbons.
The Constraint Index is calculated as follows:
Log10 (fraction of n-hexane remaining)
Constraint Index
Log10 ~Tractlon or 3-melhylpentane rema m lngl
The Constraint Index approximates the ratio of the cracking
rate constants for the two hydrocarbons. Zeolites suitable for the
present invention are those having a Constraint Index in the
approximate range of 1 to 12. Constraint Index (CI) values for some
typical zeolites are:
CAS CI
-
ZSM-5 8.3
ZSM-ll 8.7
ZSM-12 2
ZSM-23 9.1
ZSM-35 4-5
ZSM-38 2
TMA Offretite 3.7
Beta 0.6
ZSM-4 0 5
H-Zeolon 0.4
REY 0-4
Amorphous Silica-alumina 0.6
Erionite 38
~L~J ~3f~3
F-2834 - 8 -
It is to be realized that the above Constraint Index values
typically characterize the specified zeolites but that such are the
cumulative result of several variables used in determination and
calculation thereof. Thus, for a given zeolite depending on the
test temperature, the Constraint Index may vary within the indicated
approximate range of 1 to 12. Likewise, other variables such as the
crystal size of the zeolite, the presence of possible occluded
contaminants and binders intimately combined with the zeolite affect
the Constraint Index. It will accordingly be understood by those
skilled in the art that the Constraint Index, as utilized herein,
while affording a highly useful means for characterizing the
zeolites of interest is approximate, taking into consideration the
manner of its determination, with probability, in some instances, of
compounding variable extremes.
The class of zeolites defined herein is exemplified by
ZSM-5, ZSM-ll, ZSM-12, ZSM-23, ZSM-35, ZSM-38, and other similar
materials. U.S. Patent No. 3,702,886, describes ZSM-5.
ZSM-ll is described in U.S. Patent No. 3,709,979.
ZSM-12 is described in U.S. Patent No. 3,832,449.
ZSM-23 is described in U.S. Patent No. 4,076,842.
ZSM-35 is described in U.S. Patent No. 4,016,245.
ZSM-38 is described in U.S. Patent No. 4,046,859.
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, followed by base exchange with ammonium
salts followed by calcination.
Natural zeolites may sometimes be converted to this type
zeolite catalyst by various activation procedures and other
treatments such as base exchange, steaming, alumina extraction and
calcination, in combinations. Natural minerals which may be so
treated include ferrierite, brewsterite, stilbite, dachiardite,
epistilbite, heulandite, and clinoptilolite. The preferred
4~33
F-2834 - 9 -
crystalline aluminosilicates are ZSM-5, ZSM-ll, ZSM-12, ZSM-23,
ZSM-38 and ZSM-35, with ZSM-5 particularly preferred.
When synthesized in the alkali metal form, the zeolite is
conveniently converted to the hydrogen form, generally by
intermediate formation of the ammonium form as a result of ammonium
ion exchange and calcination of the ammonium form to yield the
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 weight may be used. Thus, 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 Table,
including, by way of example, nickel, copper, zinc, palladium,
calcium or rare earth metals.
In practicing the desired conversion process, it is
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, McNamee-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-beryllia, silica-titania as well as ternary
compositions, such as silica-alumina-thoria,
F-2834 - 10 -
silica-alumina-zirconia, silica-alumina-magnesia and silica-magnesia-
zirconia. The relative proportions of zeolite component and
inorganic oxide gel matrix may vary widely with the zeolite content
ranging from between 1 to 99 percent by weight and more usually in
the range of 55 to about 80 percent by weight of the composite.
The method of forming the particle or extrudate of the
desired diameter size is accomplished according to conventional
techniques in the prior art, and no particular novelty is claimed in
the method of making the material. In general for forming
cylindrical extrudates, a mixture of a suitable zeolite such as
ZSM-5 containing a hydrogenation component and an inorganic oxide
matrix such as alumina in a suitable weight ratio, i.e., 65 weight
percent zeolite; 35 weight percent alumina; are mixed with water and
extruded through a .0625 inch to a conventional commercial extruder
such as a California pellet mill having the appropriate diameter
hole, i.e., from 0.3 to 1.3 mm (.0125 to .05 inch). The extrudate
is then dried and calcined at elevated temperatures, i.e., 538C
(1000F) for about 3 hours. Neither the drying nor the calcination
time is particularly critical, and it is the conventional time used
in making extrudates.
Polylobes including trilobes and quadrulobes are known in
the art and conventional processes for their preparation are
disclosed in U. S. Patent 4,447,314.
Extrusion is also useful for forming other shapes of
particles that are desirable for this catalyst. These are formed by
using suitable shaped orifices in the die plate of the extruder.
U.S. Patent No. 3,674,680 to Hoekstra et al. represents a suitable
extrudate shape; U. S. 3,674,680 uses small catalyst shapes wherein
all points in the particles are less than 0.4 mm (0.015 inch) from a
surface of the particle. Shapes having a configuration of cross,
clover leaf, quadrulobe or trilobe such as in U. S. 3,857,780 are
operable here, so long as the maximum dimension of the cross section
of the lobes or shapes is such that the maximum diffusion distance
is less than 0.6 mm (0.025 inches) from the particle surface.
33
F-2834 - 11 -
Spherical or near-spherical particles within the specified
dimension range of the surface are also operable herein. These
generally are formed from freshly extruded material, for example, by
a process where the extrudate is reshaped in a spinning vessel or
drum. Such equipment is available commercially as marumerizers from
the Eli Lily Company and others.
33
F-2834 - 12 -
Examples 1 - 3
Three different lube basestocks were prepared from an
Arabian Light crude. Typical properties of the three materials are
given in Table 1.
Charge stock A, a 345 bright stock, was prepared by propane
deasphalting the vacuum resid. The deasphalted oil was then
furfural extracted to reduce the aromatics content.
Charge stock B, a 339 heavy neutral, was prepared by vacuum
distillation. This heavy vacuum distillate was then furfural
extracted to reduce the aromatics content.
Charge stock C, a 318 light neutral, was also prepared by
vacuum distillation. This light vacuum distillate was also furfural
extracted to lower the aromatics content.
F-2834 - 13 -
TABLE 1
Charge Stock Properties
A B C
FEED Arab Lt. BS Arab Lt HN Arab Lt. LN
Density, g/cl
API 26.2 27.5 30.8
H, wt percent 13.1 13.5 13.58
S, wt percent 1.18 1.05 .82
N, ppm 130 97 60
Total Acid No. 0.25 0.12 --
CCR, wt percent .77 0.05 --
(Conradson Carbon Residue)
Pour Point, C/F49/120 49/120 38/100
KV 54C/130F, cs 48.15 17.68
KV 100C/212F, cs27.77 11.3 5.32
KV 149C/300F, cs8.749
Distillation
IBF, C/F 433/812 396/744 365/689
5 Vol Percent484/903 452/846 399/751
501/933 466/870 407/765
519/966 477/890
534/993 483/902 424/796
543/1009 488/910
555/1031 492/918 435/815
568/1054 496/925
579/1074 502/935
508/947
519/967 463/866
528/982 469/877
EP (End Point) 540/1004 ---
83
F-2834 - 14 -
EXAMPLE 4
A nickel ZSM-5 catalyst combined with an alumina matrix and
extruded to a diameter of 1.6 mm (0.0625 inch) was prepared as
follows:
Dried sodium form ZSM-5 crystals and Kaiser SA alumina
powder (alpha alumina monohydrate) were blended in a ratio of 65
parts by wt ZSM-5 and 35 parts by wt A1203 (both on a dry
basis), extruded to 1.6 mm (.0625 inch) diameter cylinders and
calcined for three hours at 538C (1000F). The calcined product
was exchanged with NH4N03 solution to low sodium and then with
ni(N03)2 solution. It was dried and then calcined at 538OC
(lû00F). The nickel content was 1.3 weight percent and the sodium
was 0.02 weight percent.
The calcined extrudate was then steamed at 482C (900F)
for six hours. The measured alpha activity was 68.
4~3
F-2834 - 15 -
EXAMPLE 5
A nickel ZSM-5 catalyst combined with an alumina matrix and
extruded to a diameter of 0.8 mm (0.03125 inch) was prepared as
follows:
This catalyst was pepared by the same procedure as Example
4, except that the extrudates produced were 0.8 mm (1/32 inch)
diameter.
The nickel content was 1.0 weight percent and the sodium
was 0.03 weight percent. The measured alpha activity was 75.
The physical properties of the catalyst prepared in
accordance with Examples 4 and Examples 5 are shown in Table 2.
TABLE 2
Example 4 5
Extrudate Diam., in./mm.0625/1.6.03125/0.8
Packed Density, g/cc 0.57 0.616
Particle Density, g/cc0.919 1.037
Real Density, g/cc 2.736 2.760
Pore Volume, cc/g 0.722 0.602
Surface Area, m2/g 352 338
Ni, wt percent 1.3 1.0
Na, ppm 200 300
Alpha Activity 68 75
Pore Volume Distribution
PV Percent of Pores in
0- 30 Angstrom Diam. 19 24
30- 50 9 7
50- 80 19 13
80- 100 10 9
100- 150 13 22
150- 200 4 13
200- 300 6 9
300+ 20 3
F-2834 - 16 -
It is to be understood that the catalyst can be employed in the
fresh state or can be subjected to a mild steaming treatment at
elevated temperatures from 427 to 816C (800 to 1500F) and
preferably 427 to 649C (800 to 1200F). The treatment may be
accomplished in atmospheres of 100 percent steam or at atmospheres
consisting of steam and a gas which is substantially inert to the
zeolites. A similar treatment can be accomplished at lower
temperatures and elevated pressures, e.g., 177 to 371C (350 to
700F) at 10 to about 200 atmospheres.
In the experiments which follow a catalyst of Examples
4 and 5 were treated with steam at 482C (900F) for 6 hours.
F-2834 - 17 -
EXAMPLE 6
In order to demonstrate that the novel process of this
invention does not result in increased benefit with all feedstocks,
experiments were carried out using the raffinate identified as Feed
C in Table 1. As can be seen, this feedstock is outside the scope
of this invention since its 50 volume percent boiling point is below
482C (900F). Catalysts of Examples 4 and 5 were used to process
this feed material to a pour point of -7C (+20F). The dewaxing
conditions are as follows:
Pressure 400 PSIG/2,900 kPa
LHSV 1.0
Hydrogen Circulation 2500 SCFB/450 v/v
Temperature 282-360C/540-680F
Figure 1 shows the results obtained utilizing the catalyst of
Example 4 having a 1.6 mm (0.0625 inch) diameter extrudate. Figure
2 shows the results obtained using the catalyst of the invention,
0.8 mm (0.03125 inch) diameter extrudate (Example 5). Both
catalysts had undergone previous dewaxing cycles with subsequent
high temperature hydrogen reactivations.
Following relatively rapid initial aging 2.8 to 3.9C (5 to
7F) per day, both catalysts lined out and aged at about 0.56C
(1F) per day. Thus, no advantage is evident for dewaxing light
stocks with catalysts having maximum diffusion distances less than
0.8 mm (.03125 inch) i.e., 1.6 mm (.0625 inch) diameter extrudate.
33
F-2834 - 18 -
EXAMPLE 7
The catalysts of Examples 4 and 5 were used to dewax the
heavy neutral raffinate identified as Feed B to a pour point of -7C
(+20F). The dewaxing conditions were identical to those used in
Example 6.
The results of this experiment are shown in Figure 3.
As can be seen in Figure 3 the dotted line represents the
results obtained with the 1.6 mm (0.0625 inch) diameter catalyst,
i.e., Example 4, whereas the solid line represents a plot of the
catalyst of Example 5, i.e., 0.8 mm (.03125 inch) diameter. As can
be seen, a lower start of cycle temperature was obtained using the
0.8 mm (.03125 inch) catalyst, i.e., 282C (540F) as opposed to the
1.6 mm (.0625 inch) catalyst, i.e., 291C (555F). The 1.6 mm
(.0625 inch) catalyst aged at 2.22C (4F) per day, whereas the 0.8
mm (.03125 inch) catalyst aged at 2.44C (4.4F) per day,
essentially equivalent. As can be seen from the above data,
although the 0.8 mm (.03125 inch) catalyst resulted in a lower
start-of-cycle temperature, its aging rate was equal to the 1.6 mm
(.0625 inch) catalyst.
- ~Z~ 3
F-2834 - 19 -
EXAMPLE 8
After reaching end of cycle conditions, both the catalysts
used in Example 6 were reactivated by treatment with hydrogen at
about 482C (900F) for 24 hours. They were then recontacted with
the same feedstock used in Example 6 under the exact same operating
conditions, and the results are shown in Figure 4. As can be seen,
during the second cycle, the 0.8 mm (.03125 inch) diameter catalyst
represented by the solid line had a start-of-cycle temperature of
289C (552F) as compared to 293C (560F) for the 1.6 mm (.0625
inch) diameter catalyst. However, the 0.8 mm (.03125 inch) diameter
catalyst aged at 3.11C (5.6F) per day whereas the 1.6 mm (.0625
inch) diameter catalyst aged at 5.56C (10F) per day.
Quite obviously, the above experimental results demonstrate
the lower aging characteristics of utilizing the smaller extrudate.
This advantage was not observed with 318LN (Example 6). Moreover,
the advantages of the invention become more pronounced with
reactivated catalysts.
33
F-2834 - 20 -
EXAMPLE 9
Following the runs of Example 8 both catalysts were again
reactivated by heating the same in the presence of hydrogen at 482C
(900F) for 24 hours. The two catalysts were then used to dewax a
bright stock having the properties set forth under Feed A in Table
1. The results of the experimentation are shown in Figure 5. The
base case catalyst 1.6 mm (0.0625 inch) diameter extrudate, as shown
by the dashed line, had a 299C (570F) start-of-cycle activity and
aged at 5C (9F) per day. The invention catalyst 0.8 mm (0.03125
inch) diameter extrudate, as shown by the solid line, had a 284C
(544F) start-of-cycle activity and aged at only 2.33C (4.2F) per
day. This result demonstrates that lowering the catalyst's maximum
diffusion distance improved performance for dewaxing bright stock
lube material.
33
F-2834 - 21 -
EXAMPLE 10
The previous examples have cited 0.8 mm (1/32nd inch)
diameter extrudate catalyst. This example demonstrates that a
similar catalyst stability benefit can also be achieved by crushing
large extrudates to smaller particles having a diffusion length
encompassed in this invention. The catalyst of Example 4 was
crushed and sieved to two sizes: 20/30 mesh and 60/80 mesh. The
average particle sizes were 0.6 mm (0.025 inch) and 0.1 mm (.005
inch), respectively. Maximum diffusion distances were 0.3 mm
(0.0125 inch) and 0.06 mm (0.0025 inch), respectively. These three
catalysts were used to dewax an Arabian Light bright stock (see
Table 3 for properties) at 0.75 LHSV. The results are shown in
Figure 6. The catalyst of Example 4 extrudate catalyst had a
start-of-cycle activity of 278C (533F) and aged at 1.67C (3F)
per day. The 20/30 mesh catalyst had a start-of-cycle activity of
278C (532F) and aged at only 0.83C (1.5F) per day. Going to
even smaller particles gave a slight start-of-cycle activity
benefit.
F-2834 - 22 -
TABLE 3
Arabian Light Bright Stock Properties
Stock D
Specific Gravity, g/cl 0.90
Viscosity KV~ 100C 29.71
KV~ 149C t3000F) 9.31
Aniline Point 251
Elemental Analysis Weight Percent
Carbon 85.53
Hydrogen 13.16
Sulfur 1.31
Nitrogen (ppm)130
Basic Nit. (ppm) loo
Metals (ppm)
Ni 0 4
V ND
Fe ND
Cu ND
Na 5.2
Furfural (ppm) 8.0
Oil Content weight percent 80.62
Refractive Index (70C) 1.4872
CCR (weight percent) 0.71
Paraffins 18.8
Naphthenes 42.0
Aromatics 39.2
Distillation Weight Percent C/F
489/912
507/944
527/980
537/998
45O 554/1030
56 563/1045
