Note: Descriptions are shown in the official language in which they were submitted.
~Z32~355
F-1756 -1-
HYDROISOMERIZATION OF CATALYTICALLY DOCKSIDE
LUBRICATING OILS
The present invention relates to a method of nydrofinishing
catalytically hydrodewaxed lubricating oil stocks (lube oil) by the
hydroiscmerizatlon of the residual wax content which has not been
removed by the dew axing process.
Catalytic dew axing of hydrocarbon oils to reduce the
temperature at which separation of waxy hydrocarbons occurs is a known
process and is described, for example, in the Oil and Gas Journal,
January 6, 1975, pages 69-73. A number of patents have also issued
describing catalytic dew axing processes, for example, U.S. Reissue
Patent No. 28,398 describes a process for catalytic dew axing with a
catalyst comprising a zealot of the ZSM-5 type and a
hydrogenation/dehydrogenation component. A process for hydra-
dew axing a gas oil with a ZSM-5 type catalyst is also described in
U.S. Patent No. 3,956,102. A mordant catalyst containing a Group VI
or a Group VIII metal may be used to Dixie a low V.I. distillate from
a waxy crude as described in U.S. Patent No. 4,100,056. U.S. Patent
No. 3,755,138 esquires a process for mild solvent dew axing to remove
high quality wax from a lube stock, which is then catalytically
dockside to specification pour point.
Catalytic dew axing processes may be followed by other
processing steps such as hydrodesulfurization and denitrogenation in
order to improve the qualities of the product. For example, U.S.
Patent No. 3,668,113 describes a catalytic dew axing process employing
a mordant dew axing catalyst which is follower by a catalytic
hydrodesulfurization step over an alumina-based catalyst. U.S. Patent
No. 3,894,938 describes a hydrodewaxing process using a ZSM-5 type
catalyst which is followed by conventional hydrodesulfurization of the
dockside intermediate.
1232855
F-1756 -2-
In catalytic dew axing processes using shape selective
catalysts such as ZSM-5, the waxy components particularly the
n-paraf~ins, are cracked by the zealot into light gases, such as C
and C3 and some heavier olefinic fragments which remain in the lube
oil boiling range. These olefinic fragments are unstable to oxidation
so that the hydrodewaxed oil is subsequently hydrogenated over
catalyst to saturate the olefins and improve the oxidation stability
of the oil. The hydrogenation catalysts generally used are mild
hydrogenation catalysts such as Comic type. The color of the
oil may also be improved in Tunis hydrofinishing.
Tune waxy components in heavy lube fractions, particularly
bright stock, contain not only the normal paraffins, but also slightly
branched paraffin's and cycloparaffins. In the bright stock, the
normal paraffins comprise the so-called microcrystalline wax while the
15 slightly branched paraffins and cycloparaffins comprise so-called
petrolatum wax. When a shape selective catalyst such as HZSM-5 is
used, the microcrystalline wax cracks much faster than the petrolatum
wax. As a result, when sufficient microcrystalline wax is cracked to
meet the pour point requirement of, for example, -7C, there it still
I some petrolatum wax left. This small amount of petrolatum wax does
not impair pour point specification but it makes the oil fail an
overnight cloud point (ON) test (ASTM D-2500-66).
The overnight cloud point test is conducted my placing the
finished oil overnight in a refrigerator set at 5.5C (10F) above the
25 pour point specified, for example -7C (20F). An oil sample passes
the test if it remains clear and bright, but some oils, particularly
hydrodewaxed oil become dull due to growth of wax crystals, and fail
the test. The oil fails the overnight cloud test as soon as the wax
crystals nucleate and grow to sufficient sizes of 0.05 to 0.5 microns.
If the severity of the dew axing is increased significantly,
the product can be made to meet the overnight cloud point (ON)
test. for instance, decreasing the product pour point to -23C
(-10F) by increasing temperature or decreasing space velocity, can
produce a product that passes the ON test at -1C (30F).
12~2855
-3-
However, this decrease in pour point leads to increased
cost because of reaction severity and, particularly, to
decreased yield.
It would therefore be desirable to find some
way of improving the quality of the catalytically de-
waxed product so that it is capable of passing the ON
test without incurring the disadvantages of a higher
severity dew axing and, in particular, to avoid the
losses in yield concomitant upon such a treatment.
We have now found that much of the petrolatum
wax can be converted to more soluble isomers by hydra-
isomerization under mild conditions with little loss in
yield. This treatment results in a product which has a
markedly improved overnight cloud point (a lower cloud
point temperature). The hydrofinished products are also
characterized by improved oxidation stability and rota-
live freedom from color bodies. These improvements are
obtained, moreover, with only minimal losses in the yield
of the finished oil.
According to the present invention, there is
therefore provided a process for improving the overnight
cloud point of a catalytically dockside lubricating oil
stock containing petrolatum wax which is relatively in-
soluble comprising contacting said oil with a catalyst
having both an acidic function and a hydrogenation-
dehydrogenation function in the presence of hydrogen
at hydroisomerization conditions to produce a product
containing branched chain isoparaffins which are more
soluble at low temperatures, and wherein the conversion
of said oil to lower boiling components is less than
about 10 weight percent.
The isomerization is carried out in the presence
of hydrogen under isomerization conditions of elevated
temperature and pressure, typically from 200C to 450C
(392F to 842F), 400 to 25,000 spa (58 to 3626 prig)
with space velocities of 0.1 to 10 ho LHSV.
issue
F-1756 -4-
The feed stock for the present isomerization process is a
catalytically dockside oil which typically has a boiling point above
the distillate range (above about 343C (650F)). Products of this
kind are lubricating (lube) oil stocks which possess a
5 characteristically low content of n-paraffins but containing residual
small quantities of slightly branched chain paraffins and
cycloparaffins which are responsible for unacceptable results in the
ON test. The content of these petrolatum waxes is typically in the
range 0.5 to 5 percent by weight of the oil but slightly higher or
lower contents my be encountered, depending upon the nature of the
feed stock to the dew axing step and the conditions (catalyst severity)
used in the dew axing. Typical boiling ranges for lube stocks will be
over 345C depending upon the grades.
The present process is applicable to stocks other than lube
5 stocks when a low wax content is desired in the final product and, in
particular, when a product passing a test similar to ON is desired.
Thus, the process may also be applied to catalytically dockside
distillate range materials such as heating oils, jet fuels and diesel
fuels.
'The catalytically dockside oil may be produced by any kind of
catalytic dew axing process, for example, processes of the kind
described in U.S. Patents Nos. 3,668,113 and 4,110,056 but is
especially useful with oils produced by dew axing processes using shape
selective catalysts such as ZSM-5 or ZSM-ll, ZSM-23, ZSM-35, or
25 ZSM-38. Dew axing processes using catalysts of this kind are
described, for example, in U.S. Patents Nos. Rev 28,398, 3,956,102,
3,755,138 and 3,894,938 to which reference is made for details of such
processes. Since dew axing processes of this kind are invariably
operated in the presence of hydrogen they are frequently referred to
30 as hydrodewaxing processes and, for this reason, the dockside oil may
be obtained from a process which may be described either as catalytic
dew axing or catalytic hydrodewaxing. For convenience, the term
- 1232~55
F-1756 -5-
"catalytic dew axing" will be used in this specification to cover both
designations. When used in combination with the present
hydrofinishing process, the catalytic dew axing step need not be
operated at such severe conditions as would formerly have been
necessary in order to meet all product specifications - especially the
pour point and the ON specification - because the present process
will improve the quality of the product and in particular, will
improve its pour point and ON performance and stability. However, if
desired, the catalytically dockside oil may be hydrodesulfurized or
denitrogenated prior to the present hydrofinishing step in order to
remove heterocyclic contaminants which might otherwise adversely
affect catalyst performance. Hydrotreating steps of this kind are
described, for example, in U.S. Patents Nos. 3,668,113 and 3,894,938
to which reference is made for details of these steps.
The catalysts used in the present hydrofinishing process are
hydroisomerization catalysts which comprise an acidic component and a
hydrogenation-dehydrogenation component (referred to, for convenience,
as a hydrogenation component) which is generally a metal or metals of
Groups IBM JIB, VA, VIA or VOW of the Periodic Table (I'M C and U.S.
National bureau of Standards approved Table as shown, for example, in
the Chart of the Fisher Scientific Company, Catalog No. 5-702-10).
The preferred hydrogenation components are the noble metals of Group
VOW, especially platinum but other noble metals such as palladium,
gold, sliver, rhenium or rhodium may also be used. Combination of
25 noble metals such as platinum-rhenium, platinum-palladium,
platinum-iridium or platinum-iridium-rhenium together with
combinations with non-noble metals, particularly of Groups VIA and
VOW are of interest, particularly with metals such as cobalt;
nickel, vanadium, tungsten, titanium and molybdenum, for example,
30 platinum-tungsten, platinum-nickel or platinum-nickel-tungsten. Base
metal hydrogenation components may also be used, especially nickel,
cobalt, molybdenum, tungsten, copper or zinc. Combinations of base
metals such as cobalt-nickel, cobalt-molybdenum, nickel-tungsten,
issue
F-1756 -6-
cobalt-nickel-tungsten or cobalt-nickel-titanium may also be used.
because the isomerization which is desired is favored by strong
hydrogenation activity in the catalyst, the more active noble metals
such as platinum and palladium will normally be preferred over the
less active base metals.
The metal may be incorporated into the catalyst by any
suitable method such as impregnation or exchange onto the zealot.
The metal may be incorporated in the form of a cat ionic, anionic or
neutral complex, such as Pt(NH3)4+, and cat ionic complexes of
0 this type will be found convenient for exchanging metals onto the
zealot. Anionic complexes are also useful for impregnating metals
into the zealots.
The amount of the hydrogenation-dehydrogenation component is
suitably from 0.01 to 10 percent by weight, normally 0.1 to 5 percent
by weight, although this will, of course, vary with the nature of the
component, less of the highly active noble metals, particularly
platinum, being required than of the less active metals.
The acidic component of the zealot may be porous amorphous
material such as an acidic clay, alumina, or silica-alumina but the
porous, crystalline zealots are preferred. The crystalline zealot
catalysts used in the catalyst comprise a three dimensional lattice of
Sue tetrahedral cross linked by the sharing of oxygen atoms and which
may optionally contain other atoms in the lattice, especially aluminum
in the form of Aye tetrahedral the zealot will also include a
25 sufficient cat ionic complement to balance the negative charge on the
lattice. Zealots have a crystal structure which is capable of
regulating the access to an egress from the intracrystalline free
space. This control, which is effected by the crystal structure
itself, is dependent both upon the molecular configuration of the
30 material which is or, alternatively, is not, to have access to the
internal structure of the zealot and also upon the structure of the
zealot itself. The pores of the zealot are in the form of rings
which are formed by the regular disposition of the tetrahedral making
up the anionic framework of the crystalline aluminosilicate, the
35 oxygen atoms themselves being bonded to the silicon or aluminum atoms
i232~355
F-1756 -7-
at the centers of the tetrahedral A convenient measure of the extent
to which a zealot provides this control for molecules of varying
sizes to its internal structure is provided by the Constraint Index of
the zealot: zealots which provide but highly restricted access to
and egress from the internal structure have a high value for the
Constraint Index and zealots of this kind usually have pores of small
size. Contrariwise, zealots which provide relatively free access to
the internal zealot structure have a low value for the Constraint
Index. The method by which Constraint Index is determined is
I described fully in U.S. Patent 4,016,218 to which reference is made
for details of the method together with examples of Constraint Index
for some typical zealots. because Constraint Index is related to the
crystalline structure of the zealot but is nevertheless determined by
means of a test which exploits the capacity of the zealot to engage
15 in a cracking reaction, that is, a reaction dependent upon the
possession of acidic sites and functionality in the zealot, the
sample of zealot used in the test should be representative of
zeolitic structure whose Constraint Index is to be determined and
should also possess requisite acidic functionality for the test.
I Acidic functionality may, of course, be varied by artifices including
base exchange, steaming or control of sil1ca:aluminai~atio.
A wide variety of æ idle zealots may be used in tune present
including large pore zealots such as natural faujasite, mordant,
zealot X, zealot Y, ZSM-2û and zealot beta, small pore zealots
25 such as zealot A and zealots which are characterized by a Constraint
Index from 1 to 12 and a silica alumina ratio of at least 12:1.
Specific zealots having a Constraint index of 1 to 12 and
silica alumina ratio include ZSM-5, ZSM-ll, ZSM-12, ZSM-35 and ZSM-38
which are disclosed, respectively, in U.S. Patent Nos. 3,702,886;
30 3,709,979; 3,832,449; 4,016,245 and 4,046,859. Of them, ZSM-5 is
preferred. Highly siliceous forms of ZSM-ll are described in European
Patent Publication No. 14059 and of ZSM-12 in European Patent
Publication No. 13630. Reference is made to these patents and
applications for details of these zealots and their preparation.
- ` ~2321~55
F-1756 -8-
The silica alumina ratios referred to in this specification
are the structural or framework ratios, that is, the ratio for the
Sue to the Aye tetrahedral which together constitute the
structure of which the zealot is composed. This ratio may vary from
the silica alumina ratio determined by various physical and chemical
methods. For example, a gross chemical analysis may include aluminum
which is present in the form of cations associated with the acidic
sites on the zealot, thereby giving a low silica alumina ratio.
Similarly, if the ratio is determined by thermogravimetric analysis
lo (TOGA) of ammonia resorption, a low ammonia titration may be obtained
if cat ionic aluminum prevents exchange of the ammonium ions onto the
acidic sites. These disparities are particularly troublesome when
certain treatments such as the dealuminization methods described below
which result in the presence of ionic aluminum free of the zealot
structure are employed. Due care should therefore be taken to ensure
that the framework 6ilica:alumina ratio is correctly determined.
Large pore zealots such as zealots Y, ZSM-20 and beta are
useful in the present process. Zealots of this kind will normally
have a Constraint Index of less than l. They may be used on their own
or in combination with a zealot having a Constraint Index of l to 12
and such combinations may produce particularly desirable results. A
combination of zealots Y and ZSM-5 has been found to be especially
good.
Zealot beta is disclosed in U.S. Patent No. 3,308,069 to
25 which reference is made for details of this zealot and its
preparation.
When the zealots have been prepared in the presence of
organic cations they are catalytically inactive, possibly because the
int~acrystalline free space is occupied by organic cations from the
forming solution. They may be activated by heating in an inert
atmosphere at 540C for one hour, for example, followed by base
exchange with ammonium salts followed by calcination at 540C in air.
The presence of organic cations in the forming solution may not be
absolutely essential to the formation of the zealot; but it does
35 appear to favor the formation of this special type of zealot.
,
.,.
issue
F-1756 -9-
Some natural zealots may sometimes be converted to zealots
of the desired type by various activation procedures and other
treatments such as base exchange, steaming, alumina extraction and
calcination.
When synthesized in the alkali metal form, the zealot is
conveniently converted to the hydrogen form generally by intermediate
formation of the ammonium form as a result of ammcnium ion exchange
and calcinat$on of the ammonium form to yield the hydrogen form. It
has been found that although the hydrogen form of the zealot
catalyzes the reaction successfully, the zealot may also be partly in
the alkali metal form although the selectivity to alpha-picoline is
lower with the zealot in this form.
It may be desirable to incorporate the zealot in another
material resistant to the temperature and other conditions employed in
the process. Such matrix materials include synthetic or naturally
occurring or in the form ox gelatinous precipitates or gels including
mixtures of silica and metal oxides. Naturally occurring clays can be
composite with the zealot and they may be used in the raw state as
originally mined or initially subjected to calcination, acid treatment
I or chemical modification. Alternatively the zealot may be
composite 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-zirconia,
25 silica-alumina-magnesia or silica-magnesia-zirconia. The matrix may
be in the Norm of a Vogel. The relative proportions of zealot
component and inorganic oxide gel matrix may vary widely with the
zealot content typically ranging from l to 99 percent by weight and
more usually in the range of 5 to 80 percent weight of the composite.
30 The matrix itself may have catalytic properties of an acidic nature
which may contribute to the functionality of the catalyst. Zealots
may also be combined with amorphous catalysts and other porous
materials such as alumina. The combination of zealots Y and ZSM-5
with alumina has been found to be particularly desirable.
2 3~35 5
F-175~ -10-
The isomerization-reaction is one which requires a relatively
small degree of acidic functionality in the catalyst. ekes
this the zealot may have a very high silica alumina ratio since this
ratio is inversely related to the acid site density of the catalyst.
Thus, structural silica alumina ratios of 50:1 or higher are preferred
and in fact the ratio may be much higher e.g. 100:1, 200:1, 500:1,
1000:1 or even higher. Since zealots are known to retain their
acidic functionality even at very high silica alumina ratios of the
order of 25,000:1, ratios of this magnitude or even higher are
0 contemplated.
If the zeolite`selected may be produced in the desired highly
siliceous form by direct synthesis, this will often be the most
convenient method for obtaining it. Zealot beta, for example, is
known to be capable of being synthesized directly in forms having
15 silica alumina ratios up to 100:1, as described in U.S. Patents Nos.
3,308,069 and Rye 28,341 which describe zealot beta, its preparation
and properties in detail. Reference is made-to these patents for
these details. Zealot Y, on the other hand, can be synthesized only
in forms which have silica alumina ratios up to about Sol and in order
20 to achieve higher ratios, resort may be made to various techniques to
remove structural aluminum so as to obtain a more highly siliceous
zealot. The same is true of mordant which, in its natural or
directly synthesized form has a silica alumina ratio of about 10:1.
Zealot ZSM-20 may be directly synthesized with silica alumina ratios
25 of 7:1 or higher, typically in the range of 7:1 to 10:1, as described
in U.S. Patents Nos. 3,972,983 and 4,021,331 to which reference is
made for details of this zealot, its preparation and properties.
Zealot ZSM-20 also may be treated by various methods to increase its
silica alumina ratio.
Control of the silica alumina ratio of the zealot in its
as-synthesized form may be exercised by an appropriate selection of
the relative proportions of the starting materials, especially the
silica and alumina precursors, a relatively smaller quantity of the
alumina precursor resulting in a higher silica alumina ratio in the
35 product zbolite, up to the limit of the synthetic procedure. If
1~23Z~SS
F-1756
higher ratios are desired and alternative syntheses affording the
desired high silica alumina ratios are not available, other techniques
such as those described below may be used in order to prepare the
desired highly siliceous zealots.
A number of different methods are known for increasing the
structural silica alumina ratio of various zealots. Many of these
methods rely upon the removal of alumni w from the structural
framework of the zealot by chemical agents appropriate to this end.
A considerable amount of work on the preparation of aluminum deficient
10 faujasites has been performed and is reviewed in Advances in Chemistry
Series No. 121, Molecular Sieves, GUT. Kerr, American Chemical
Society, 1973. Specific methods for preparing dealuminized zealots
are described in the following, and reference is made to them for
details of the method: Catalysis by Zealots (International Symposium
15 on Zealots, Lyon, September 9-11, 1980), Elsevier Scientific
Publishing Co., Amsterdam, 1980 (dealuminization of zealot Y with
silicon tetrachloride); U.S. 3,442,795 and GOB. 1,058,188 (hydrolysis
and removal of aluminum by chelation); GOB. 1,061,847 (acid extraction
of aluminum); U.S. 3,493,519 (aluminum removal by steaming and
20 chelation); U.S. 3,591,488 (aluminum removal by steaming); U.S.
4,273,753 (dealuminization by silicon halides and oxyhalides); U.S.
3,691,099 (aluminum extraction with acid); U.S. 4,û93,560
(dealuminization by treatment with salts); U.S. 3,9 *,791 (aluminum
removal with Cry) solutions); U.S. 3,506,400 (steaming followed by
25 chelation); U.S. 3,640,681 (extraction of aluminum with
acetylacetonate followed by dehydroxylation); U.S. 3,836,561 (removal
of aluminum with acid); DEMOS 2,51û,740 (treatment of zealot with
chlorine or chlorine-contrary gases at high temperatures), NO
7,604,264 (acid extraction), JAY 53,101,003 (treatment with ETA or
30 other materials to remove aluminum) and J. Catalysis 54 295 (1978)
(hydrothermal treatment followed by acid extraction).
Because of their convenience and practicality the preferred
dealuminization methods for preparing the present highly siliceous
zealots are those which rely upon acid extraction of the aluminum
3sfrom the zealot by contacting the zealot with an acid, preferably a
` lZ~2855
F-1756 -12-
mineral acid such as hydrochloric acid. With zealot beta the
dealuminization proceeds readily at ambient and mildly elevated
temperatures and occurs with minimal losses in crystallinity, to form
high silica forms of zealot beta with silica alumina ratios of at
least 100:1, with ratios of 200:1 or even higher being readily
attainable.
Highly siliceous forms of zealot Y may be prepared steaming
- or by acid extraction of structural aluminum (or both) but because
zealot Y in its normal, as-synthesized condition, is unstable to
acid, it must first be converted to an acid-stable form. Methods for
doing this are known and one of the most common forms of
acid-resistant zealot Y is known as "Ultra stable Y" (US) which is
described in U.S. Patent Nos. 3,293,192 and 3,402,996 and the
publication, Society of Chemical Engineering (London) Monograph
15 Molecular Sieves, page 186 (1968) by TV McDaniel and PI Maker.
Reference is made to these for details of the zealot and its
preparation. In general, "ultra stable" refers to Y-type zealot which
is highly resistant to degradation of crystallinity by high
temperature and steam treatment and is characterized by a R
20 content therein R is Nay K or any other alkali metal ion) ox less than
4 weight percent, preferably less than 1 weight percent, and a unit
cell size less than 24.5 Angstroms and a silica to alumina mole ratio
in the range of 3.5 to 7 or higher. The ultra stable form of Y-type
zealot is obtained primarily by a substantial reduction of the alkali
25 metal ions and the unit cell size reduction of the alkali metal ions
and the unit cell size reduction. The ultra stable zealot is
identified both by the smaller unit cell and the low alkali metal
content in the crystal structure.
The ultra stable form of the Y-type zealot can be prepared by
30 successively base exchanging a Y-type zealot with an aqueous solution
of an ammonium salt, such as ammonium nitrate, until the alkali metal
content of the Y-type zealot is reduced to less than 4 weight
percent. The base exchanged zealot is then calcined at a temperature
of 540C to 300C for up to several hours, cooled and successively
35 base exchanged with an aqueous solution of an ammonium salt until the
,, .
12~2855
F-1756 -13-
alkali metal content is reduced to less than 1 weight percent,
followed by washing and calcination again at a temperature of 540C to
800C to produce an ultra stable zealot Y. The sequence onion
exchange and heat treatment results in the substantial reduction of
the alkali metal content of the original zealot and results in a unit
cell shrinkage which is believed to lead to the ultra high stability
of the resulting Y-type zealot.
The ultra stable zealot Y may then be extracted with acid to
produce a highly siliceous Norm of the zealot. The acid extraction
10 may be made in the same way as described above for zealot beta.
Methods for increasing the silica alumina ratio of zealot Y
by acid extraction are described in U.S. Patents 4,218,307, 3,591,488
and 3,691,099, to which reference is made for details of these methods.
Zealot ZSM-20 may be converted to more highly siliceous
15 forms by a process similar to that used for zealot Y. First, the
zealot is converted to an "ultra stable" form which is then
dealuminized by acid extraction. The conversion to the ultra stable
form may suitably be carried out by the same sequence of steps used
or preparing ultra stable Y. The zealot is successively
20 base-exchanged to the ammonium form and calcined, normally at
temperatures above 700C. The calcination should be carried out in a
deep bed in order to impede removal of gaseous products, as
recommended in Advances in Chemistry Series, No. 121, ox cit. Acid
extraction of the "ultra stable" ZSM-2~ may be effected in the same way
25 as described above for zealot beta.
Highly siliceous forms of mordant may be made by acid
extraction procedures of the kind described, for example, in U.S.
Patent Nos. 3,691,099, 3,591,488 and other dealuminization techniques
which may be used for mordant are disclosed, for example, in U.S.
30 Patent Nos. 4,273,753, 3,493,519 and 3,442,795. Reference is made to
these patents for a full description of these processes.
Another property which charæterizes the zealots which may
be used in the present catalysts is their hydrocarbon sorption
capacity. The zealot used in the present catalysts should have a
35 hydrocarbon sorption capacity for Nixon of greater than 5
.
1232l355
F-1756 -14-
preferably greater than 6 percent by weight at 50C. The hydrocarbon
sorption capacity is determined by measuring the sorption at 50C, 20
mm Hug (2666 Pa) hydrocarbon pressure in an inert carrier such as
helium.
Hydrocarbon sorption capacity (%)
Wt. of z~r~be------~~ x 100
The sorption test is conveniently carried out by TOGA with helium
as a carrier gas flowing over the zealot at 50C. The hydrocarbon of
10 interest e.g. Nixon is introduce into the gas stream adjusted to 20
mm Hug hydrocarbon pressure and the hydrocarbon uptake, measured as the
increase in zealot weight is recorded. The sorption capacity may then
be calculated as a percentage.
The zealot hydroisomerization catalysts are generally used in a
15 cat ionic form which gives the required degree of acidity and stability at
the reaction conditions used. The zealot will be at least partly in the
hydrogen form, such as HZSM-5, HO, in order to provide the acidic
functionality necessary for the isomerization but cation exchange with
other cations, especially alkaline earth cations such as calcium and
20 magnesium and rare earth cations such as lanthanum, curium, praseodymium
and neodymium, may be used to control the proportion of protonated sites
and, consequently, the acidity of the zealot. Rare earth forms of the
large pore zealots X and Y, REX and RYE, are particularly useful as are
the alkaline earth forms of the ZSM-5 type zealots, such as MgZSM-5,
25 provided that sufficient acidic activity is retained for the
isomerization.
cause the isomerization reactions require both acidic and
hydrogenation-dehydrogenation functions in the catalyst with a suitable
balance between the two functions for the best performance, it may be
30 desirable to use more active hydrogenation components such as platinum
with the more highly acidic components. Conversely, if the acidic
component has but a low degree of acidic activity it may become possible
to use a less active hydrogenation component, such as nickel or
nickel-tungsten.
i232~355 - .
F-1756 -15-
The feed stock is isomerized over the hydroisomerization catalyst
in the presence of hydrogen under isomerization conditions of elevate
temperature and pressure. The reaction temperature should be high enough
to obtain sufficient isomerization activity but low enough to reduce
cracking activity in order to avoid losses in product yield. The
temperature will generally be in the range of 20ûC to 450C (392F to
842F) and preferably 250C to 375C (482F to 7û7F). With the more
highly acidic catalysts lower temperatures within these ranges should
normally be employed in order to minimize the conversion to lower boiling
10 range products. Reaction pressures (total) are usually from 400 to 25000
spa ~58 to 3626 prig), and more commonly in the range of 3500 to 12000
ha (507 to 1740 prig). Spa e velocities are normally held in the range
0.1 to 10, preferably 0.5 to 5, ho 1 LHSV. Hydrogen circulation rates
of 30 to 700, usually 200 to 500,
15 null 1 (168 to 3932, usually 1123 to 281û SCF/Obl) are typical. The
hydrogen partial pressure will normally be at least 50 percent of total
system pressure, more usually 80 to 90 percent or-total system pressure.
The isomerization reaction is carried out so as to minimize
conversion to lower boiling range products, especially to gas
20 (Cluck). Curing the isomerization, tune petrolatum wax (slightly
branched paraffins and cyclupa~affins, generally of at least ten carbon
atoms and usually C16-C40) are converted to branch chain
iso-paraffins which are more soluble at low temperature. Conversion to
lower boiling range products is normally not greater than 10 percent by
25 weight and in favorable cases is less than 5 percent by weight, for
example, 3 percent by weight.
The invention is illustrated by the following Examples in which
all parts, proportions and percentages are by weight unless stated to the
contrary.
30 examples 1-22
Apparatus: A laboratory continuous down-flow reactor was used.
It was equipped with feed reservoir and pump, reactor temperature
controllers and monitoring devices, gas regulators, flow controller and
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pressure gauges. Products were discharged into a sample receiver through
a grove loader which controlled the operating pressure. Light products
were collected in a dry ice cold trap downstream of the sample receiver.
Uncondensed gases were first passed through a gas sampler and then Noah
scrubber before passing through a gas meter.
Startup Procedure: The reactor was packed with 10 cc of
catalyst. It was activated by passing hydrogen at 370C for I hours
with the same Ho circulation rate and pressure as in the projected
run. A line out period of 12 hours was followed after the reaction
temperature had been set and feeding started.
Jo The operating conditions and catalysts used in the Examples are
shown in Table 1 below.
sample Preparation and Testing procedures: The collected oil
product was vacuum stripped at 125C/0.05 mm Hug I Pa) for two hours to
remove moisture and volatile fractions. The yield was calculated based
on the final stripped product. The products were filled in 5.7 cm No. 1
screw capped vials and placed in a refrigerator kept at -1C for 16 hours
to develop haze.
. . _
To evaluate and quantify the degree of cloudiness of each oil
product, a set of standards was prepared. These were binary mixtures of
a catalytically hydrodewaxed then solvent dockside bright stock (this
material passed the ON test) and a hydrodewaxeq bright stock (this
material failed the ON test). The mixtures of one component in the
other ranged from O to 100 percent. Such a set of standards furnished
25 the whole range of cloudiness from 0-100%. The slight dark coloration of
the solvent dockside oil was removed by percolating it through basic
alumina column to obtain the same hue as that of the hydrodewaxed bright
stock before it was used in the preparation of the standards.
To grade the clarity-cloudiness of the product oil, both were
30 contained in the same size vial and kept side by side in a refrigerator
at -1C for 16 hours. The clarity/cloudiness of the product was then
matched against the standard. A quality number corresponding to the
percent of content of solvent dockside oil component in a particular
standard was assigned to the oil sample to express its degree of
us clarity. For example, a number of 80 means that particular oil sample
12~2855
F-1756 -17-
has the same degree of clarity as that ox a standard containing 80%
solvent dockside oil.
The conditions used in the hydroisomerization and the results
obtained are shown in Table 1 below. All runs were conducted at a
pressure of 403û spa (584.5 prig).
~Z32~SS
F-1756 -18-
TABLE 1
Example H2/Char~e
No. Catalyst Temp. C null LHSV Yield % Quality
1 A 315 178 0.82 -- 20
2 A 178 -- - 40
3 A 345 178 0.82 97.4 20
4 B 260 356 0.53 83.6 20
B 288 178 1.2 90.3 30
6 9 345 178 1.2 96.1 20
7 B 290 178 1 99.4 10
8 C 293 178 1.1 99.1 20
9 C 315 178 0.86 97.1 10
C ~345 178 1.1 98.7 30
11 C 370 178 0.95 96.9 30
12 D 288 178 1.35 95.6 40
13 D 315 178 1.2 -- 70
14 D 275 356 0.65 20
D 260 356 0.61 -- 30
16 P 260 356 ,0~53 99 50
17 D 315 356 0.56 98 50
18 D 345 356 û.55 93.5 60
19 D 345 356 0.47 93.9 60
D 320 356 0.45 99.7 70
21 D 293 356 0.45 99.8 80
22 D 370 356 0.46 92.4 95
Catalysts:
A: Tao (0.3 % Pi)
B: Pd/HY
C: Pt/Mg Betty (0.3% Pi; 50% My Beta/50% Aye ;
Beta Sue = 100:1~
D: Pd/REY/HZSM-5/A1203 (0.35% Pod; 50% ROY% HZSM-5, 35% Aye)
These results show that a high degree of improvement in ON may be achieved
by hydroisomerization with little loss in yield.
