U.S. patent application number 11/374726 was filed with the patent office on 2006-10-05 for paraffinic hydroisomerate as a wax crystal modifier.
Invention is credited to Loren L. Ansell, Adeana R. Bishop, Patrick Brant, Michel A. Daage, W. Berlin Genetti, Jack W. Johnson, Daniel F. Ryan, Eric B. Sirota.
Application Number | 20060219597 11/374726 |
Document ID | / |
Family ID | 37069027 |
Filed Date | 2006-10-05 |
United States Patent
Application |
20060219597 |
Kind Code |
A1 |
Bishop; Adeana R. ; et
al. |
October 5, 2006 |
Paraffinic hydroisomerate as a wax crystal modifier
Abstract
Heavy fractions of paraffinic lubes produced over dewaxing
catalysts are effective as wax crystal modifiers for being
hydrocarbons notwithstanding that such heavy fractions have pour
points above that of the liquid hydrocarbon.
Inventors: |
Bishop; Adeana R.; (Baton
Rouge, LA) ; Ansell; Loren L.; (Baton Rouge, LA)
; Genetti; W. Berlin; (Baton Rouge, LA) ; Daage;
Michel A.; (Baton Rouge, LA) ; Ryan; Daniel F.;
(Brewster, MA) ; Sirota; Eric B.; (Flemington,
NJ) ; Johnson; Jack W.; (Clinton, NJ) ; Brant;
Patrick; (Seabrook, TX) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
37069027 |
Appl. No.: |
11/374726 |
Filed: |
March 14, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60668384 |
Apr 5, 2005 |
|
|
|
Current U.S.
Class: |
208/15 ;
208/27 |
Current CPC
Class: |
C10M 2205/17 20130101;
C10G 73/00 20130101; C10L 1/1616 20130101; C10M 2205/173 20130101;
C10M 111/04 20130101; C10M 2205/022 20130101; C10L 10/16 20130101;
C10L 1/16 20130101; C10L 1/1691 20130101; C10N 2030/08 20130101;
C10M 2205/0225 20130101; C10M 169/041 20130101 |
Class at
Publication: |
208/015 ;
208/027 |
International
Class: |
C10L 1/04 20060101
C10L001/04; C10G 73/02 20060101 C10G073/02 |
Claims
1. A method for modifying the process by which wax crystals form in
a paraffinic containing hydrocarbon liquid when the temperature of
the liquid is lowered comprising adding to the liquid an effective
amount of a heavy fraction of a paraffinic lube produced over a
dewaxing catalyst.
2. The method of claim 1 wherein the heavy fraction has a final
boiling point above 850.degree. F. (454.degree. C.).
3. The method of claim 2 wherein the paraffinic lube is produced
from a Fischer-Tropsch product.
4. The method of claim 2 wherein the heavy fraction is extracted as
a waxy material from said paraffinic lubes.
5. The method of claim 2 wherein the paraffinic lube is produced
from a polyethylene wax.
6. The method of claim 3 wherein the hydrocarbon liquid is a base
lube oil and wherein the heavy fraction is added in a pour point
lowering amount.
7. The method of claim 3 wherein the hydrocarbon liquid is a first
base lube oil, and the heavy fraction is added in a pour point
lowering amount in the form of a second base oil containing a
greater fractional amount of the heavy fraction than that contained
in the first lube oil.
8. The method of claim 7 wherein the second lube oil is added to
the first lube oil in an amount sufficient to provide a blend
containing from about 0.01 parts by weight to about 0.5 parts by
weight of a heavy fraction.
9. The method of claim 8 wherein the amount of heavy fraction in
the second lube is in the range of about 0.10 to about 0.70 parts
by weight.
10. The method of claim 3 wherein the hydrocarbon liquid is a crude
oil and the heavy fraction is added in an amount sufficient to
lower the temperature for wax deposition.
11. The method of claim 3 wherein the hydrocarbon liquid is a
diesel or heating fuel and the heavy fraction is in the form of a
second base oil containing a greater fractional amount of the heavy
fraction than that contained in the first lube oil, and second base
oil is added in an amount to lower the cold filter plugging
point.
12. The method of claim 11 wherein the second lube oil is added to
the first lube oil in an amount sufficient to provide a blend
containing from about 0.01 parts by weight to about 0.5 parts by
weight of a heavy fraction.
13. The method of claim 12 wherein the amount of heavy fraction in
the second lube is in the range of about 0.10 to about 0.70 parts
by weight.
14. A fuel composition comprising a major amount of a diesel or
heating fuel and a heavy fraction of a paraffinic lube produced
over a dewaxing catalyst, the heavy fraction being in an amount
sufficient to lower the cold filter plugging point of the fuel.
15. The method of claim 14 wherein the heavy fraction has a final
boiling point above about 850.degree. F. (454.degree. C.).
16. A blend of a first paraffinic containing hydrocarbon liquid and
a second paraffinic containing hydrocarbon liquid wherein the
second liquid contains a heavy hydrocarbon fraction having a final
boiling point greater than 850.degree. F. (454.degree. C.) in an
amount greater than that in the first liquid and wherein the amount
of the heavy fraction in the total blend is in the range of from
about 0.01 to 0.5 parts by weight.
17. The blend of claim 16 wherein the second liquid contains from
about 0.10 to 0.70 parts by weight of the heavy hydrocarbon
fraction.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/668,384 filed Apr. 5, 2005.
FIELD OF THE INVENTION
[0002] The present invention is concerned broadly with modifying
the low temperature properties of hydrocarbon fluids and more
particularly with the use of a heavy fraction of paraffinic lubes
produced from a Fischer-Tropsch product as a wax crystal
modifier.
BACKGROUND OF INVENTION
[0003] Wax crystal modifiers are additives used in the petroleum
industry to improve the cold flow properties of numerous
hydrocarbon fluids such as crude oils, diesel fuels, lubricating
oils and the like. Basically, wax crystal modifiers function by
modifying, in some way, the process by which wax crystals form in
solutions when the solution temperature is lowered. For example,
they may interact with paraffins in the hydrocarbon fluid to delay
onset of crystallization, they may modify the morphology of the wax
to a shape less likely to plug a filter or to form a gel; and they
may operate to prevent fresh paraffin from adding to wax. Hence,
wax crystal modifiers are used in lubricating oils as pour point
depressants and in diesel fuels as cold filter plugging point
depressants. They find use also as cloud point depressants in fuels
and wax inhibitors in crude oils.
[0004] Wax crystal modifiers commonly employed include chlorinated
hydrocarbons, polyolefins and ethylene-vinyl ester copolymers.
SUMMARY OF INVENTION
[0005] Surprisingly it has been discovered that heavy fractions of
paraffinic lubes produced over dewaxing catalysts are effective as
wax crystal modifiers. Indeed it has been discovered that when
added to a base lube oil the aforesaid heavy fractions will lower
the pour point of the base lube oil notwithstanding that the heavy
fraction has a pour point well above that of the base oil.
[0006] By heavy fractions of dewaxed paraffinic lubes is meant
those fractions having a final boiling point exceeding 850.degree.
F. (454.degree. C.), preferably exceeding 950.degree. F.
(510.degree. C.) and even exceeding 1000.degree. F. (538.degree.
C.) after 95 mass percent of the lube has been removed. Typically,
the lube will be one having an initial boiling point exceeding
700.degree. F. (371 .degree. C.).
[0007] In a preferred embodiment of the invention the heavy
fraction is derived from a Fischer-Tropsch product by catalytically
hydroisomerizing the product to produce a lube oil and distilling
the lube oil to obtain a high boiling, heavy fraction and a lower
boiling fraction.
[0008] In one embodiment of the invention, the process by which wax
crystals form in a first paraffinic containing hydrocarbon liquid
is modified by adding to it a second lube containing greater
amounts by weight of a heavy fraction than the first liquid, the
second lube being added in an amount sufficient to modify the wax
crystal formation process of the first liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1 to 6 are graphical illustrations of various
embodiments of the invention and also depict results of Examples 1
to 6 respectively.
DETAILED DESCRIPTION OF INVENTION
[0010] The wax crystal modifiers of the present invention comprise
the heavy fractions of paraffinic lubes produced over dewaxing
catalysts. Such paraffinic lubes include those lubes obtained from
a mineral oil by hydrocracking, hydroisomerization, solvent
extraction and hydroprocessing and combinations thereof, and lubes
obtained from polyethylene and from Fischer-Tropsch paraffinic
products. In a preferred embodiment of the invention the heavy
fraction of a paraffinic lube suitable for use as a wax crystal
modifier is derived from a Fischer-Tropsch product that has been
catalytically dewaxed.
[0011] Preferably the Fischer-Tropsch product is obtained by
conducting a Fischer-Tropsch process under conditions sufficient to
produce products containing greater than 20 lbs. of 700.degree.
F.+(371.degree. C.+) product per 100 lbs. CO converted and more
preferably greater than 24 lbs. of 700.degree. F.+(371.degree. C.+)
product per 100 lbs. CO converted. This can be achieved by at least
one of (a) the appropriate selection of process operating
conditions and (b) choice of catalyst.
[0012] Preferably, the Fischer-Tropsch process is conducted at
temperatures no greater than 430.degree. F. (221.degree. C.), for
example, from about 330.degree. F. to about 430.degree. F.
(148.degree. C. to 221.degree. C.). More preferably the reaction is
conducted at no greater than 410.degree. F. (210.degree. C.).
Operating pressures typically are in the range of from about 10 to
about 600 psia, preferably from about 250 to about 350 psia, and
space velocities of about 1000 to 25,000 cc/cc/hour.
[0013] The Fischer-Tropsch process preferably is conducted in a
slurry bubble column reactor. In slurry bubble column reactors
catalyst particles are suspended in a liquid and gas is fed into
the bottom of the reactor through a gas distributor. As the gas
bubbles rise through the reactor the reactants are absorbed into
the liquid and diffuse to the catalyst where they are converted to
both gaseous and liquid products. Gaseous products are recovered at
the top of the column and liquid products are recovered by passing
the slurry through a filter which separates the solid catalyst from
the liquid. An optimal method for operating a three phase slurry
bubble column is disclosed in EP 0450860 B1 which is incorporated
herein by reference in its entirety.
[0014] Suitable Fischer-Tropsch catalysts comprise one or more
Group VIII metals such as Fe, Ni, Co, and Ru on an inorganic oxide
support. Additionally, the catalyst may also contain a promoter
metal. One suitable catalyst for the process of the invention is
cobalt promoted with rhenium supported on titania having a Re:Co
weight ratio in the range of about 0.01 to 1 and containing about 2
to 50 wt % cobalt. Examples of such catalysts can be found in U.S.
Pat. No. 4,568,663; U.S. Pat. No. 4,992,406; and, U.S. Pat. No.
6,117,814.
[0015] Another suitable and preferred catalyst for the
Fischer-Tropsch process comprises cobalt and especially cobalt and
rhenium on a support comprising primarily titania and a minor
amount of cobalt aluminate. In general the support will contain at
least 50 wt % titania and preferably from 80 to about 97 wt %
titania based on the total weight of the support. About 20 to 100
wt %, and preferably 60 to 98 wt % of the titania of the support is
in the rutile crystalline phase with the balance being the anatase
crystalline phase or amorphous phases. The amount of cobalt
aluminate in the binder is dependent upon the amount of cobalt and
aluminum compounds used in forming the support. Suffice it to say
that sufficient cobalt is present in the support to provide a
cobalt/aluminum atomic ratio greater than 0.25, preferably from 0.5
to 2, and more preferably about 1. Thus, at a Co/Al ratio of 0.25
about half the aluminum oxide is present as cobalt aluminate. At a
Co/Al ratio of 0.5 substantially all the alumina oxide present is
present as cobalt aluminate. At Co/Al ratios above 0.5 the support
will contain cobalt titanate in addition to cobalt aluminate and be
essentially free of alumina.
[0016] The support is typically formed by spray drying a suitable
aqueous slurry of titania, alumina binder material and optionally
silica binder material into a purged chamber with heated air at an
outlet temperature of about 105.degree. C. to 135.degree. C. Spray
drying produces a spherical support with a size range of about 20
to 120 microns. This spray dried support is then calcined at
temperatures in the range of 400.degree. C. to 800.degree. C.,
preferably about 700.degree. C. Next the calcined material is
impregnated with an aqueous solution of a cobalt compound,
preferably cobalt nitrate, in an amount sufficient to convert, upon
calcination, at least part of the alumina to cobalt aluminate.
Preferably sufficient cobalt compound is used to convert from 50%
to 99+% of the alumina to cobalt aluminate. Therefore, the amount
of cobalt compound added during the preparation of the support will
correspond to an atomic ratio of Co:Al in the range of 0.25:1 to
2:1 and preferably 0.5:1 to 1:1. Indeed, it is especially preferred
that the support produced be substantially free of alumina.
[0017] Calcination of the cobalt impregnated support preferably is
conducted in air at temperatures in the range of about 700.degree.
C. to about 1000.degree. C., preferably about 800.degree. C. to
about 900.degree. C.
[0018] Typically the support will have a surface area in the range
of from about 5 m.sup.2/g to about 40 m.sup.2/g and preferably from
10 m.sup.2/g to 30 m.sup.2/g. Pore volumes range from about 0.2
cc/g to about 0.5 cc/g and preferably from 0.3 cc/g to 0.4
cc/g.
[0019] In preparing the catalyst the cobalt and rhenium promoter
are composited with the support by any of a variety of techniques
well known to those skilled in the art, including impregnation
(either co-impregnation with promoters or serial
impregnation--either by spray drying or by the incipient wetness
techniques). Since a preferred catalyst for fixed bed
Fischer-Tropsch processes is one wherein the catalytic metals are
present in the outer portion of the catalyst particle, i.e., in a
layer no more than 250 microns deep, preferably no more than 200
microns deep, a preferred method of preparing the catalyst is the
spray method which is described in U.S. Pat. No. 5,140,050,
incorporated herein by reference or in EP 0 266 898, incorporated
herein by reference. For slurry Fischer-Tropsch processes,
catalysts are preferably made by incipient wetness impregnation of
spray-dried supports. When using the incipient wetness impregnation
technique, organic impregnation aids are optionally employed. Such
aids are described in U.S. Pat. No. 5,856,260, U.S. Pat. No.
5,856,261 and U.S. Pat. No. 5,863,856, all incorporated herein by
reference.
[0020] The amount of cobalt present in the catalyst will be in the
range of 2 to 40 wt % and preferably 10 to 25 wt % while the
rhenium will be present in weight ratios of about 1/20 to 1/10 of
the weight of cobalt.
[0021] By selecting the appropriate Fischer-Tropsch reaction
conditions, the appropriate catalyst, or both as described above
the amount of high molecular weight waxy product formed is
favored.
[0022] A 450.degree. F.+(232.degree. C.+) cut of the waxy product
is separated from other hydrocarbons produced in the
Fischer-Tropsch process and then is catalytically hydroisomerized.
Suitable hydroisomerization catalysts typically include at least
one Group VIII hydrogenating metal component selected from Pt, Pd,
Rh, Ir and preferably at least Pt on a refractory metal oxide
support, or preferably on a zeolite support. The catalyst typically
contains from about 0.1 wt % to about 5 wt % metal. Examples of
such catalysts include a noble metal, e.g., Pt on ZSM-23, ZSM-35,
ZSM-48, ZSM-57 and ZSM-22.
[0023] A preferred catalyst is Pt on ZSM-48. The preferred
preparation of ZSM-48 is disclosed in U.S. Pat. No. 5,075,269
incorporated herein by reference. The Pt is deposited on the ZSM-48
by techniques well known in the art such as impregnation, either
dry or by incipient wetness techniques.
[0024] Isomerization is conducted under conditions of temperatures
between about 500.degree. F. (260.degree. C.) to about 900.degree.
F. (482.degree. C.), preferably 550.degree. F. (288.degree. C.) to
725.degree. F. (385.degree. C.), pressures of 1 to 10,000 psi
H.sub.2, preferably 100 to 2,500 psi H.sub.2, hydrogen gas rates of
50 to 3,500 SCF/bbl, and a space velocity in the range of 0.25 to 5
v/v/hr, preferably 0.5 to 3 v/v/hr.
[0025] Following isomerization, the isomerate may be distilled into
cuts of various ranges. The heavy fraction used as a wax crystal
modifier typically will have a final boiling point after 95 mass
percent has been distilled off of greater than 850.degree. F.
(454.degree. C.), and preferably greater than 950.degree. F.
(510.degree. C.), and even higher.
[0026] In an alternate embodiment of the invention the heavy
fraction used as a wax crystal modifier may be obtained as the waxy
fraction removed from a dehazed paraffinic oil. The waxy fraction
may be removed by techniques known in the art such as filtration,
precipitation, distillation, adsorption and the like.
[0027] In yet another embodiment of the invention the heavy
fraction used as wax crystal modifier is obtained by catalytically
hydroisomerizing a poly-ethylene wax and distilling the isomerate,
taking as the heavy fraction the material boiling above
1050.degree. F. (566.degree. C.).
[0028] Low molecular weight polyethylene waxes are derived from
high density polyethylene. They are hard, crystalline materials
that melt to a low viscosity. They do not contain any chemical
functional groups. A range of products may be obtained using
different distillation conditions. Examples are the Polyflo.RTM.
products available commercially from SasolWax. These polyethylene
waxes may be catalytically hydroisomerized in a process similar to
that described above for waxy Fischer-Tropsch feeds.
[0029] The heavy fraction or waxy material is added to the lube to
be pour point depressed in an amount sufficient to lower the pour
point of the oil. Typically this will be in the range of from about
0.01 to 30 wt % based on the weight of the lube oil.
[0030] Lube base oils that may have their pour point depressed with
the additive of the invention include lube oils derived from
paraffinic Fischer-Tropsch products and conventional lube oils
prepared from petroleum feedstocks.
[0031] In one aspect of the invention, the heavy fraction may be
added to the lube to be pour point depressed without having been
separated from the dewaxed paraffinic lube of which it constitutes
a fraction. Thus, a first base lube containing some or no heavy
fraction may be blended with a second lube containing an amount of
a heavy fraction greater than the first lube. The amount of second
lube blended with the first lube will be an amount sufficient to
lower the pour point of the first lube. In general, the amount of
the second lube added to the first lube is that amount which will
provide a lube blend containing between about 0.01 to 0.50 parts by
weight of a heavy fraction, preferably between 0.01 and 0.30 and
more preferably between 0.01 and 0.20.
[0032] In general, to provide a pour point depressing effect upon
blending, the amount of the heavy fraction in the second lube will
be at least 0.10 parts by weight of the second lube, preferably
0.20 parts by weight, more preferably 0.50 and most preferably 0.70
parts by weight of the second lube.
[0033] The fractional amounts of the heavy fraction, i.e., the
material having a final boiling point of greater than 850.degree.
F. (454.degree. C.) can be determined by any suitable method for
determining boiling point distribution, such as, fractional
distillation or by simulated boiling point distribution measurement
by gas chromatographic distillation.
EXAMPLES
[0034] In these Examples the pour point was determined by test
method ASTM D-5950 and the cloud point by ASTM D5773.
[0035] Also, the Pt/ZSM-48 catalyst used was prepared according to
U.S. Pat. No. 5,075,269 by adding the Pt compound by impregnation
followed by calcination and reduction.
Example 1
[0036] Fischer-Tropsch wax was processed over Pt/ZSM-48 in a wide
cut mode. A wide boiling feed fraction, nominally 430.degree. F.
(221.degree. C.) plus material was hydroisomerized under conditions
sufficient to reduce the pour point and cloud point of the product.
The wide boiling product from this process was fractionated into a
730-975.degree. F. (388-524.degree. C.) fraction and a 975.degree.
F.+(524.degree. C.+) fraction. The pour point and cloud point for
the 730-975.degree. F. fraction were -18.degree. C. and -6.degree.
C. respectively. The pour point and cloud point of the 975.degree.
F. fraction were -9.degree. C. and 11.degree. C. respectively. When
the 975.degree. F.+fraction was added to the 730-975.degree. F.
fraction it was observed that the pour point decreased dramatically
with little increase in cloud point at low addition rates. The
results are shown in FIG. 1.
[0037] As can be seen, at about 5% addition of 975.degree. F.+a
maximum pour point depressant effect is observed.
Example 2
[0038] A hazy Fischer-Tropsch lube was prepared by
hydroisomerization of a nominal 430.degree. F. (221.degree. C.)
fraction over Pt/ZSM-48 at approximately 610.degree. F.
(321.degree. C.) at 250 psig H.sub.2 and 1 LHSV. The resulting
product was fractionated to produce the 1000.degree. F.+fraction
having a pour point of -5.degree. C.
[0039] A conventional basestock produced from catalytic dewaxing
having a viscosity of 4.33 cSt and a pour point of -20.degree. C.
was combined with the hazy fraction of Fischer-Tropsch lube, having
a pour point of -5.degree. C. and a cut point of 1000.degree.
F.+(538.degree. C.). The pour point is significantly reduced from
20.degree. C. to -30.degree. C. with the addition of 10% by weight
of the heavy GTL lube. The results are shown in FIG. 2.
Example 3
[0040] A conventional petroleum derived basestock produced from
catalytic dewaxing having a viscosity of 5.98 cSt and a pour point
of -16.degree. C was combined with a hazy fraction of
Fischer-Tropsch lube, having a pour point of -5.degree. C., a cloud
point of 23.degree. C. and a cut point of 1000.degree. F.+and
prepared as described in Example 2. At about 20% addition of heavy
FT oil, a maximum reduction in pour point from -16.degree. C. to of
-24.degree. C. is obtained. The results are given in FIG. 3.
Example 4
[0041] A conventional petroleum derived basestock produced from
catalytic dewaxing having a viscosity of 5.98 cSt and a pour point
of -16.degree. C. was combined with an of Fischer-Tropsch lube
which had the haze selectively removed, having a pour point of
-5.degree. C., a cloud point of 13.degree. C. and a cut point of
950.degree. F.+(510.degree. C.). In this example, at only 5-10
percent addition, the maximum pour point reduction was obtained of
a change from -16.degree. C. pour point to -21.degree. C. pour
point. The cloud point in this example was increased only slightly,
from -10.degree. C. to -7.degree. C. In contrast with Example 3
where a hazy 1000.degree. F.+(371.degree. C.) oil was used for pour
point depression, this example shows a smaller pour point
depression response for the adsorbate de-hazed oil. The results are
shown in FIG. 4.
Example 5
[0042] A conventional petroleum derived basestock produced from
catalytic dewaxing having a viscosity of 5.98 cSt and a pour point
of -16.degree. C. was combined with the haze fraction removed from
a sample of hazy Fischer-Tropsch lube prepared as described in
Example 2. Before de-hazing the lube had a pour point of -5.degree.
C., a cloud point of 36.degree. C. and a cut point of 950.degree.
F.+(510.degree. C.). The haze removed from this lube had a cloud
point of 50.degree. C. and a pour point above room temperature. The
results are given in FIG. 5.
Example 6
[0043] Polyethylene wax, with a MW of 1100 and a melting point of
approximately 110.degree. C. was converted in a batch reactor over
a ZSM-48 catalyst for 2 hours at 655.degree. F. (346.degree. C.) at
500 psig hydrogen. The product produced from this catalytic
reaction had the following boiling distribution. As can be seen
from the GCD data, the isomerate product contains 67% 700.degree.
F.+(371.degree. C.+) material. TABLE-US-00001 GCD Mass Percent Off
320.degree. F. 4.47 500.degree. F. 15.89 700.degree. F. 32.31
850.degree. F. 47.98 950.degree. F. 59.65 1050.degree. F. 72.08
[0044] The total liquid product from this process had a pour point
of -3.degree. C. and a cloud point of 36.4.degree. C. This entire
boiling range product was added to a conventional petroleum derived
basestock produced from catalytic dewaxing having a viscosity of
5.98 cSt and a pour point of -16.degree. C. The results of these
blends are shown in FIG. 6. At low concentrations, the pour point
of the resulting blend is significantly depressed relative to the
starting base stock. Although this material has a lower initial
boiling point, it is predominately 700.degree. F. (371.degree. C.)
material. This concentration of heavy lube present in this wide
boiling isomerate is sufficient to achieve the desirable pour point
reduction response.
* * * * *