Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a pxocess for the production
of white mineral oil. More particularly, this invention relates
to a two-step catalytic hydrogenation process for producing white
mineral oil of high quality and in high yields.
Various prior art processes have been satisfactory in
producing white mineral oils. For example, United States Patent
3,459,656, issued August 5, 1969, describes a two-step catalytic
process wherein the second step takes place in the presence of
a platinum group metal promoted catalyst. The pres~nt invention
is directed to an improvement in such a process.
Therefore, an object of the present invention is
to provide an improved two step catalytic process for the
production of white mineral oils. Other objects and advantages
of the present invention will become apparent hereinafter.
An improved process has now been discovered for
preparing a white mineral oil from a mineral oil distillate of
lubricating viscosity which comprises contacting this hydrocarbon
with hydrogen in the presence of a sulfur-resistant catalyst
to form a hydrogenated oil having a sulfur content reduced from
20 the sulfur content of the distillate and then second contacting
at least a portion of the hydrogenated oil with hydrogen in the
presence of a second catalys-t to form a refined oil having a
specific dispersion reduced from the specific dispersion of the
hydrogenated oil from which white mineral oil is recovered. It
has been found that significantly improved results, e.g., improved
catalytic hydrogenation selectivity and activity, are obtained
using a second catalyst which comprises a major amount of a -~ -
support, a minor, catalytically effective amount of a palladium
component and a minor amount of at least one halogen component
sufficient to improve the hydrogenation activity of the second
catalyst.
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The process of this invention has been found to be
particularly effective in providing technical and food grade
white mineral oils of high quality and in high yields, e.g.,
greater than about 90%. Suitable mineral oil distillates of
lubricating viscosity for use in the present invention include
heavy or light raw distillate oils, for instance obtained by
; distillation of a naphthenic base light reduced crude such as
Gulf Coast and California crudes. The naphthenic oils often
have a specific dispersion of at least about 130. Waxy
lubricating oil distillates from crude oils having a character-
zation factor of at least 11.5, e.g., mixed base and paraffiniccrude oils, may also be used in the present in~ention, for
example, as food grade white oil feedstocks. Typically, the
mineral oil distillates used in the present invention often
have viscosi~ies in the range of about 50 SUS to about 7500 SUS
at 100F. If the oils contain wax, they are preferably dewaxed
prior to the first contacting step, although the dewaxing can
follow this step. Dewaxing can be carried out, for example,
by using a solvent, such as me~hylethyl ketone and toluene,
to obtain an oil with a pour point (ASTM D 97) below about
25F. The pour point necessary after dewaxing is determined
by that required in the finished oil.
The first contacting step of the present process is
preferably conducted at a temperature within the range from about
600F. to about 800F., more preerably from about 650F. to
about 725F.; at a pressure within the range from about 1500 psig.
to about 5000 psig., more preferably from about 2000 psig. to
about 3000 psig.; a~ a weight hourly space velocity (WHSV~ of
about 0.1 to about 1.0, more preferably from about 0.25
to about 1.0; and at a hydrogen to mineral oil distillate
ratio within the range from about 1000 s.c.f./b. to about
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5000 s.c.~./b., more preferably from about 1500 s.c.f./b.
to about 5000 s.c.f./b.
At least a portion of the hydrogenated oil from
this first contacting step is subjected to a second contacting.
This second contacting preferably occurs at a temperature in
the range from about 400F. to about 650F., more preEerably
from about 450F. to about 600F.; at a pressure in the range
from about 1500 psig. to about 5000 psig., more preferably from
about 2000 psig. to about 3000 psig.; at a WHSV from about 0.1
to about 1.0, more preferably from about 0.25 to about 1.0; and
at a hydrogen to hydrogenated oil ratio within the range from
about 500 s.c.f./b. to about 5000 s.c.f./b., more preferably ;~
from about 1500 s.c.f./b. to about 5000 s.c.f./b.
The first catalyst of the first contacting step can
be any of the sulfur resistant, non-precious metal hydrogenation
catalysts some of which are conventionally employed in the
hydrogenation of heavy petroleum oils. These catalysts typically
comprise a major amount of a support and at least one non~
precious metallic component in an amount effective to promote the
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hydrogenation of the mineral oil distillate. Examples of
suitable metallic components include tin, vanadium, chromium,
molybdenum, tungsten, iron, cobalt, nickel and mixtures thereof.
The catalytic~metals can be present in the final catalyst ~-
as the free metals or in combined form, such as the oxides
and sulfides. Preferably, ~he first catalyst contains catalytically
e~fective amounts of at least one Group VIB metal, i.e., ~ - -
chromium, molybdenum and tungsten, and at least one ~roup VIII
iron-group metal, i.e., iron, cobalt and nickel. Especially ~ -
~ preferred catalysts contain nickel, cobalt and mixtures thereof
;~ 30 together with tungsten, molybdenum and mixtures thereof. The
Group VIB metal is preferably present in amounts of fr~m about
5% to about 40%, more preferably from about 10% ~o about 30%, by -~
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wei~ht of the total catalyst, calculated as the weight o~ the
Group VIB metal oxide. The Group VIII iron-group metals are
preferably present in an amount of frorn about 2% to about 15~,
more preferably from about 4% to about 10%, by weight of the
total catalyst, calculated as the weight of the free metal.
Other metals and/or metal compounds in addition to the metal
components described above, such as rhenium, germanium and the
like, may be included in the first catalyst to improve the
properties o~ the composition.
As aforementioned, the second catalyst of the
present invention comprises a major amount of a support; a
catalytically e~fective amount of a palladium component and a
minor amount of at least one halogen component present in an
amount sufficient to improve the hydrogenation activity of
the catalyst. This second catalyst is to be distinguished
from the first catalyst in that it is not normally considered to
be sulfur-resistant. ;~
The palladium component of this second catalyst
may be present as the elemental metal or as a sulfide, oxide
or other combined forms. Preferably, the palladium component
comprises from about 0.01~ to about5.0%,more preferably from
about 0.1% to about 3.0%, by weight of the second catalyst,
calculated as elemental palladium.
Althou~h various solid refractory type carriers known
in the art may be utilized as a support for the first and second
catalysts, the ~referred support comprises a major amount of
calcined, or otherwise activated,alumina. It is preferred that
the alumina have a surface area of from about 25 m2./gm. to ~-
about 600 m2./gm. or more. The support comprises a major propor-
tion of each cataLy~t, preferably at lea~t about 60%, by ~eight,
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of the first catalyst, and preferably at leas~ about 8096, more
preferably at least about 90~ t by weight o~ ~he second catalyst.
The alumina may be derived from hydrous alumina predominating in
alumina trihydrate, alumina monohydrate, amorphous hydrous
alumin~ and mixtures thereof, which alumina when ~ormed as
pellets and ralcined, has an appaxen~ bulk density o~ from
al:out 0.60 gm./cc. to about 0.85 gm.,/cc., pore volume ~rom
abou~ 0.45 ml./$m. to about 0.70 ml./gmO, and surface area ~rom
~bout S0 m~a/gm. to about 500 m2./~m. The alumina supports
may contain, in addition, minor proportions of other well-
known refractory inorganic oxides such as sili~a, zirconia, magnesia
and the like. However, the preferred supports are substantially
pure alumina deri~ed from hydrous alumina predominating in
alumina monohydrate, amorphous hydrous alumina and mixtures
thereof. More preferably, the alumina is derived ~rom hydxous
alumina predominating in alumina monohydrate.
The alumina supports may be synthetically prepared in
any sui~able manner and may be activated prior to use by one
or more treatments including drying, calcination, steaming and
the like. For example, calcination often occurs by contacting
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the support at a temperature in the range from about 700F. to
about 1500F., preferably from about 350F. to about 1300~
for a period of time from about one hour to about 20 hours,
preferably from about one hour to about S hours. Thus, for
instance, hydrated alumina in the form o~ a hydrogel can be
precipitated from an aqueous solution of a so~uble aluminum salt
such as aluminum chloride. Ammonium hydroxide is a useful ager.t
~or effecting the precipitation~ Control of the pH to maintain
it within the values of about 7 ~o about 10 during the precipitation
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is desirable for ob~aining a good ra~e of cvnversion. Extraneous
ions, such as halide ions, which are introduced in preparing the
: hydrogel, can, if desired, be removed by filtering the alumina
hydrogel from its mo~her liquor and washing the filter cake
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with water. Also, if desired, the hydrogel can be aged, say
for a period of several days to build up the concentration of
alumina trihydrate in the hydrogel.
The alumina may be formed into macrosize particles
of any desired shape such as pills, cakes, extrudates, powders,
granules, spheres, and the like using conventional methods.
The size selected for the macrosize particles can be dependent
upon the intended environment in which the final catalyst is
to be used -- as, or example, whether in a fixed or moving bed ~j
reaction system. Thus, for example, where as in the preferred
embodiment of the present invention, tha catalysts are designed
for use in reaction systems employing a fixed bed of catalyst, the
alumina will preferably be formed into particles having a minimum,
dimension of at least about 0.01 inch. and a maximum dimension up
to about one-half inch. or one inch. or more. Spherical particles
having a diameter of about 0.03 inch. to about 0.25 inch.,
preferably about 0.03 inch. to about 0.15 inch., are often u5afult
especially in a fixed bed reactor system.
An essential cvnstituen~ of the second catalyst of the
present invention is a halogen component. Although the precise
chemistry of the assoclation of ~he halogen component with
the support, e.g., alumina, is not entirely known, the halogen
component may be referre~ to as being combined with the alumina
support or with the other ingredients of the catalyst. This
co~bined halogen may be fluorine, chlorine, bromine, and mixtures
thereof. Of these, fluorine andl particularly, chlorine are
preferred for the purposes of the present invention. The
halogen may be added to the alumina support in any suitable
manner, either during preparation of the supportj or before
or after the addition of the palladium. For example, at least
a portion of the halogen may be added at any stage of the
preparation of the support, or to the calcined catalyst support, as
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an aqueous solution of an acid such as hydrogen fluoride,
hydrogen chloride, hydrogen bromide and the like or as a
substantially anhydrous gaseous stream of these halogen-
containing components. The halogen component~ or a portion
thereof, may be composited with alumina during the impregnation
of the latter with the palladium component, for example, through
the utilization of a mixture of chloropalladic acid and hydrogen
chloride. When the catalyst is prepared by impregnating
calcined, formed alumina, for example, spheres, it is preferred
to impregnate the support simultaneously with the palladium and
halogen. In any event, the halogen will be added in such a
manner as to result in a fully composited second catalyst that
conta.ins from about 0.1% to about 4.0~ and preferably from
about 0.6~ to about 2.5~ by weight of halogen calculated on an
elemental basis. During processing, i.e., the period during
which hydrogenated oil in the presence of hydrogen is being
contacted with the second catalyst, the halogen content of
the second catalyst can be maintained at or restored to the
desired level by the addition of halogen-containing compounds,
such as carbon tetrachloride, ethyl trichloride, t-butyl
chloride and the like, to the hydrogenated oil before such
second contacting.
As indicated above, the second catalyst o~ the present
invention contains at least one palladium component~
The palladium component may be incorporated in the
catalyst in any suitable manner, such as by coprecipitation or
cogellation with the alumina~support, ion-exchange with the
alumina support and/or alumina hydrogel, or by the impregnation
of the alumina support calcination of the alumina hydrogel. --
One preferred method for adding the palladium component to
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the alumina support involves the utilization of a water
soluble compound of palladium to impregnate the alumina support
after calcination. For example, palladium may be added to the
support by comingling the calcined alumina with an aqueous
solution of chloropalladic acid. Other water-soluble compounds
of palladium may be employed as impregnation solutions,
including, for example, ammonium chloropalladate and palladium
chloride. The utilization of a palladium~chlorine compound,
such as chloropalladic acid, is preferred since it facilitates
ths incorporation of both the palladium component and at least
a minor quantity of the halogen component. Following this
impregnation, the resulting impregnated support is dried and
may be subjected to a high temperature calcination or oxidation
procedure at a temperature in the range from about 700F. to about
1500F., preferably from about 850F. to about 1300F., for a
period of time from about one hour to about 20 hours~ preferably
from about one hour to about five hours. ~he major portion of
; the halogen component may be added to this otherwise fully
~0 composited second catalyst by contacting this catalyst with a
- substantially anhydrous stream of halogen-containing gas.
If desired, the catalysts of the first and second
contactings can be hydrogen purged and/or prereduced prior to
use by heating in the presence of hydrogen, for example, at
temperature of about 300F. to 600F. for purging and of about
600F. to 1200F. for prereducing. By prereduction is meant the
chemical reaction, i.e., reduction in oxidation state, of
at least a portion of the metallic component of the catalyst.
Prereduction may be achieved by contacting the catalyst with
hydrogen for a period of time of a~ least about one-half (1/2)
hour, preferably from about 0.5 hour to about 10 hours and
at a pressure of from about 0 psig. to about 500 psig.
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Following either the first or second contacting step
of the present invention the hydrogenated oil and refined oil may
be distilled or topped if desired to remove any hydrocracked
or other light products ~ increase the flash point of the oil. The
degree of topping desired will depend on the particular lubri-
cating oil fraction being processed and the particular contacting
conditions employed. Thus, the amount of topped overhead that
may be taken off in the topping or distillation step after either
contacting may often vary from about 0 to about 50%, with about 0
to about 10% being preferred.
EXAMPLE I
This example illustrates certain of the advantages of
the present invention. -
A raw heavy lube distillate feedstock was chosen to
be trea~ed according to the present invention. This feedstock
had the following properties:
Gravity~ API 17.7
Viscosity, SUS at 100F. 900
Pour Point, F. -15
2Q Specific Dispersion 148
Sulfur content, Wt.% 0.25
Nitrogen Content, ppm. 320
Boiling Ranye, F. 700-900
This feedstock was first contacted in a fixed bed
reaction system with hydrogen in the presence of a commercially
available sulfur-resistant non-precious metal catalyst. This
catalyst had the following composition and properties:
Support Alumina
Nickel Content, Wt.% 2.3
Molybdenum Content, Wt.% 1506 (calculated as MoO3)
Phosphorus Content, Wt.% 1.4
Surface area, m2./gm. 162 -
Total Pore Volume, cc./gm~ 0.53
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This first contacting took place at the following conditions:
Temperature, F. 650
Pressure, psig. 2500
WHSV O.25
Hydrogen to Distillate
Feedstock, s.c.f./b. 2500
The hydrogenated oil produced by this first contacting
was fractionated (or topped) to remove a small amount of light
material which had been formed. The portion of this hydrogenated
oil boiling from 650F. to 900F. (the bottoms cut) had
the following properties:
Gravity, API 22.8
Viscosity, SUS at 100F. 536
Pour Point, F. -15
Specific Dispersion 106.8
Sulfur Content, wt.% 0.006%
Nitrogen Content, ppm. 5
A second catalyst was prepare~ as follows. An
extrudate of dry, calcined gamma alumina was formed from boehmite
precursor using conventional techni~ues. This ext~udate had
a surface area of 194 m2./gm. and a total pore volume o
0.60 cc./gm.
399 gms. of the extrudate was vacuum impre~nated
at 170F. with 450 ml. of an aqueous solution containing 17.39
gms. of palladium chloride, 10 ml. of 3 molar hydrochloric acid -
and 21 ml. of 3 molar nitric acid. The mixture of extrudate and
solution was allowed to equilibrate. The impregnated extrudate was
vacuum dried for two and one-half hours and then transferred
to an oven for additio~al drying at 230F. This dried ~ -
extrudate was calcined by treating this material in a dry blowing
air atmosphere at 900F. for three hours. The product of this ;
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calcination, i.e., the final unreduced second catalyst, included
2.0~ by weight of palladium, calculated as elemental palladium,
and 1.71% by weight of chloride, calculated as elemental chlorine.
200 gms. of this unreduced second catalyst was placed
in a fixed bed reaction system. At least a portion of the
palladium component was chemically reduced by contacting the
unreduced second catalyst with hydrogen, at the rate of 2 s.c.f./hr.
at atmospheric pressure and 600F. for a period of two hours.
The 650-900F. cut of the hydrogenated oil was
10 contacted with hydrogen in the presence of this second catalyst -~
to form a refined oil at the following conditions:
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Temperature, F. 500
Pressure, psig. 2500
WHSV 0.25
Hydrogen to Hydrogenated
oil s.c.f./b. 2500
This refined oil was subjected to a stripping operation to
remove light hydrocarbons formed in this second contacting
stepO The remaining refined oil had the following properties: -
Gravity, API 23.9
Viscosity, SUS at 100F. 503
Boiling Range, F. 640-900~F.
Specific Dispersion 98.9
Saybolt Color 30+
The yield of this portion of the refined oil, i.e., technical
grade white oil, is about 90% by volume, based on the volume of
the raw lube distilla~e feedstock. This technical grade
white oil easily meets or exceeds the ultra-violet absorbance
specificationssfor technical grade white mineral oil.
While this invention has been described with respect ~-
to various specific examples and embodiments, it is to be
understood that the invention is not limited thereto and that it
- can be various7y practiced within the scope of the following ~-
claims.
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