U.S. patent application number 09/931667 was filed with the patent office on 2002-08-22 for hydrogenation process.
Invention is credited to Beeckman, Jean W., Louie, Yuk-Mui, Pappal, David A., Shih, Stuart S..
Application Number | 20020112989 09/931667 |
Document ID | / |
Family ID | 23492892 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112989 |
Kind Code |
A1 |
Shih, Stuart S. ; et
al. |
August 22, 2002 |
Hydrogenation process
Abstract
A hydrocarbon hydrogenation process and a catalytic composition
having hydrogenation functionality. The catalytic composition
includes at least two noble metals supported on an inorganic,
porous crystalline phase support material having pores with
diameters of at least about 13 Angstrom Units and exhibiting, after
calcination, an X-ray diffraction pattern with at least one peak at
a d-spacing greater than about 18 .ANG. with a relative intensity
of 100, and having a benzene sorption capacity greater than about
15 grams benzene per 100 grams of the support material at 50 torr
and 25.degree. C. The noble metals are selected from the group
consisting of Pd, Pt, Rh and lr and the crystalline material is a
metallosilicate or an aluminosilicate. The hydrocarbon
hydrogenation process includes contacting a hydrocarbon feedstock
containing aromatics, olefins, or aromatics and olefins with the
catalytic composition under superatmospheric conditions; wherein
the concentration of the aromatics, olefins or aromatics and
olefins in the product is reduced.
Inventors: |
Shih, Stuart S.; (Baton
Rouge, LA) ; Louie, Yuk-Mui; (Fairfax, VA) ;
Pappal, David A.; (Haddonfield, NJ) ; Beeckman, Jean
W.; (Columbia, MD) |
Correspondence
Address: |
Gerard J. Hughes
ExxonMobil Research and Engineering Company
P. O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
23492892 |
Appl. No.: |
09/931667 |
Filed: |
August 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09931667 |
Aug 16, 2001 |
|
|
|
09378373 |
Aug 20, 1999 |
|
|
|
Current U.S.
Class: |
208/143 ;
208/144; 585/258 |
Current CPC
Class: |
C10G 45/54 20130101;
B01J 29/041 20130101 |
Class at
Publication: |
208/143 ;
208/144; 585/258 |
International
Class: |
C10G 045/00; C10G
045/32; C10G 045/44 |
Claims
1. A hydrocarbon hydrogenation process comprising contacting a
hydrocarbon feedstock containing aromatics, olefins, or aromatics
and olefins with a catalyst under superatmospheric conditions;
wherein the concentration of said aromatics, olefins or aromatics
and olefins in the product is reduced in relation to the
concentration in the feedstock; and wherein said catalyst comprises
two noble metals and is supported on a support material comprising
an inorganic, porous crystalline phase material having pores with
diameters of at least about 13 Angstrom Units and exhibiting, after
calcination, an X-ray diffraction pattern with at least one peak at
a d-spacing greater than about 18 .ANG. with a relative intensity
of 100, and having a benzene sorption capacity greater than about
15 grams benzene per 100 grams of said material at 50 torr and
25.degree. C.
2. The hydrocarbon hydrogenation process according to claim 1,
wherein said noble metals are selected from the group consisting of
Pd, Pt, Rh and Ir.
3. The hydrocarbon hydrogenation process according to claim 1,
wherein said crystalline phase material is a metallosilicate or an
aluminosilicate.
4. The hydrocarbon hydrogenation process according to claim 1,
wherein said catalyst includes at least 0.1 weight percent of said
noble metals.
5. The hydrocarbon hydrogenation process according to claim 1,
wherein said crystalline phase material exhibits, after
calcination, a hexagonal arrangement of uniformly sized pores with
diameters of at least about 13 .ANG. and a hexagonal electron
diffraction pattern that can be indexed with a d.sub.1.about. value
greater than about 18 Angstrom Units.
6. The hydrocarbon hydrogenation process according to claim 2,
wherein said crystalline phase material has an X-ray diffraction
pattern following calcination with at least one peak whose
d-spacing corresponds to the d.sub.100 value from the electron
diffraction pattern.
7. The hydrocarbon hydrogenation process according to claim 2,
wherein said noble metals are bound in a refractory inorganic
oxide, wherein said refractory inorganic oxide is selected from the
group consisting of alumina, silica, silica-alumina, titania,
zirconia, magnesia and combinations thereof.
8. The hydrocarbon hydrogenation process according to claim 1,
wherein said feedstock is a diesel fuel boiling range hydrocarbon
and said support material is M41S.
9. The hydrocarbon hydrogenation process according to claim 1,
wherein said catalyst is PtPd/M41S or PtPd/MCM-41.
10. The hydrocarbon hydrogenation process according to claim 1,
wherein said feedstock is a jet or diesel fuel boiling range
hydrocarbon.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of U.S. Ser. No. 09/378,373
filed Aug. 20, 1999.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to hydrogenation catalysts and
their use in a hydrogenation process. In particular, the present
invention relates to the hydrogenation of very low aromatic diesel
fuels and other hydrocarbon streams.
[0004] 2. Description of Related Art
[0005] Hydrogenation is adding one or more hydrogen atoms to an
unsaturated hydrocarbon (e.g., an olefin or aromatic compound).
Hydrogenation may occur either as direct addition of hydrogen to
the double bonds of unsaturated molecules, resulting in a saturated
product, or it may cause breaking of the bonds of organic
compounds, with subsequent reaction of hydrogen with the molecular
fragments. Examples of the first type (called addition
hydrogenation) are the conversion of aromatics to cycloparaffins
and the hydrogenation of unsaturated vegetable oils to solid fats
by addition of hydrogen to their double bonds. Examples of the
second type (called hydrogenolysis or hydrocracking) are cracking
of petroleum and hydrogenolysis of coal to hydrocarbon fuels.
[0006] The benefits of "purifying" petroleum fractions through
hydrogen processing have been known since the early 1930's.
However, because of a lack of cheap hydrogen and the high pressures
formerly required, the process did not develop commercially until
the middle 1950's. The advent of catalytic reforming, which made
inexpensive hydrogen-rich off-gas available, encouraged
hydrogen-processing development. Subsequent advances in catalyst
technology allowed operating pressure requirements to be reduced.
Today, hydrogenation is a well-established process both in the
chemical and petroleum refining industries and is used extensively
to prepare reformer feedstock and to some extent for catalytic
cracking feedstock preparation. Product upgrading of middle
distillates, cracked fractions, lube oils, gasolines and waxes by
means of hydrogen treating is also widespread. Severity of
treatment depends largely upon feedstock properties and the
required improvement. Cracked stocks and heavy materials call for
severe conditions.
[0007] Hydrogen treating is often justified for reasons other than
the production of superior fuels. Hydrogenation improves yields;
substantially eliminates waste-disposal problems caused by
mercaptans, phenols and thiophenols; and reduces corrosion problems
from sulfur, cyanides and organic acids. Hydrogen treating also is
important in sulfur recovery and subsequent reduction of air
pollution by sulfur acid gases.
[0008] Hydrogenation is conventionally carried out in the presence
of a catalyst that usually comprises a metal hydrogenation
component on a porous support material, such as a natural clay or a
synthetic oxide. Nickel is often used as a hydrogenation component,
as are noble metals such as platinum, palladium, rhodium and
iridium. Typical support materials include kieselguhr, alumina,
silica and silica-alumina. Depending upon the ease with which the
feed may be hydrogenated, the hydrogen pressures used may vary from
quite low to very high values, typically from about 100 to 2,500
psig.
[0009] A variety of organic compounds can be hydrogenated easily in
the presence of a catalyst. Catalytic hydrogenation of olefins can
be carried out either in gas or in liquid phase, depending on their
molecular weights. A nickel-containing catalyst and sometimes
platinum or palladium catalysts are employed. Aromatic compounds
may be reduced either in the vapor phase at atmospheric pressure or
in the liquid phase at hydrogen pressures up to 200 atmospheres
(2.times.10.sup.4 kilopascals). In the latter case, aromatics, such
as benzene, toluene, and p-cymene, can be hydrogenated readily in
the presence of a nickel catalyst. In the case of naphthalene or
substituted naphthalenes, the product may be the tetra- or
decahydronaphthalenes derivative.
[0010] Hydrogenation is an exothermic process and is generally
favored thermodynamically by lower temperatures and by higher
H.sub.2 partial pressures. However, for practical reasons,
moderately elevated temperatures are normally used and for
petroleum refining processes, temperatures in the range of 100 to
700.degree. F. are typical. Hydrogenative treatment is frequently
used in petroleum refining to improve the qualities of lubricating
oils, both of natural and synthetic origin. Hydrogenation, or
hydrotreating, is used to reduce residual unsaturation in the
lubricating oil, and to remove heteroatom-containing impurities and
color bodies. The removal of impurities and color bodies is of
particular significance for mineral oils that have been subjected
to hydrocracking or catalytic dewaxing. For both hydroprocessed
mineral and synthetic stocks, the saturation of lube boiling range
olefins is a major objective.
[0011] The extensive use of hydrogenation catalysts in the chemical
and petroleum industries for a variety of applications has led to a
need for more active catalysts and catalysts which are more sulfur
and/or nitrogen tolerant so that they can be used for longer
periods between regeneration or replacement. More active
hydrogenation catalysts increase the efficiency of a process and
enable smaller reactor beds to be used. In addition, operating
costs can be reduced by using hydrogenation catalysts that are more
sulfur and/or nitrogen tolerant.
SUMMARY OF THE INVENTION
[0012] In accordance with the present invention, a catalytic
composition having hydrogenation functionality and a hydrocarbon
hydrogenation process are provided. The catalytic composition
includes at least two noble metals which are supported on a support
material that includes an inorganic, porous crystalline phase
material exhibiting, after calcination, an X-ray diffraction
pattern with at least one peak at a d-spacing greater than about 18
.ANG. with a relative intensity of 100, and having a benzene
sorption capacity greater than about 15 grams benzene per 100 grams
of the anhydrous crystal at 50 torr and 25.degree. C. The noble
metals preferably make up at least 0.1 weight percent of the
catalytic composition. The preferred noble metals are selected from
the group consisting of Pd, Pt, Rh and Ir, and are bound in a
refractory inorganic oxide that is selected from alumina, silica,
silica-alumina, titania, zirconia, magnesia or combinations
thereof. The preferred crystalline material is a metallosilicate or
an aluminosilicate.
[0013] In one embodiment, the crystalline phase material of the
catalytic composition has, after calcination, a hexagonal
arrangement of uniformly sized pores with diameters of at least
about 13 .ANG. and a hexagonal electron diffraction pattern that
can be indexed with a d.sub.100 value greater than about 18
Angstrom Units. In a preferred embodiment, the crystalline phase
material exhibits an electron diffraction pattern, following
calcination, that can be indexed with a d.sub.100 value greater
than about 18 Angstrom Units and with at least one peak whose
d-spacing corresponds to the d.sub.100 value from the electron
diffraction pattern. The crystalline phase material exhibits a
benzene adsorption capacity of greater than about 15 grams benzene
per 100 grams of the crystalline phase material at 50 torr and
25.degree. C. The crystalline phase material of the catalytic
composition has a composition expressed as follows:
M.sub.n/q(W.sub.aX.sub.bY.sub.cZ.sub.dO.sub.h) (1)
[0014] wherein M is one or more ions; n is the charge of the
composition excluding M expressed as oxides; q is the weighted
molar average valence of M; n/q is the number of moles or mole
fraction of M; W is one or more divalent elements; X is one or more
trivalent elements; Y is one or more tetravalent elements; Z is one
or more pentavalent elements; a, b, c, and d are mole fractions of
W, X, Y, and Z, respectively; h is a number of from 1 to 2.5; and
(a+b+c+d)=1. In a preferred embodiment, W includes a divalent first
row transition metal or magnesium; X includes aluminum, boron,
gallium or iron; Y includes silicon or germanium; and Z includes
phosphorus. In another preferred embodiment, a and d are 0 and
h=2.
[0015] In another embodiment, the crystalline phase material is a
composition of matter that includes an inorganic, porous
crystalline phase material exhibiting, after calcination, an X-ray
diffraction pattern having values substantially as shown below:
1 d-spacing. d.sub.n .ANG. d.sub.n/d.sub.l relative intensity
d.sub.1 .gtoreq. 18 1.0 100 d.sub.1 - d.sub.2 0.87 .+-. 0.06 w -
m
[0016] The preferred support material is M41S and the preferred
catalysts are PtPd/M41S and PtPd/MCM-41.
[0017] The hydrocarbon hydrogenation process includes contacting a
hydrocarbon feedstock containing aromatics, olefins, or aromatics
and olefins with the catalytic composition under super-atmospheric
conditions; wherein the concentration of the aromatics, olefins or
aromatics and olefins in the product is reduced. In preferred
embodiments, the feedstock is a diesel fuel range or a jet fuel
range hydrocarbon.
[0018] The hydrogenation catalysts of the present invention are
more active than those previously used while being more sulfur and
nitrogen tolerant. Moreover, the hydrogenation catalysts of the
present invention provide increased efficiency and reduce operating
costs.
BRIEF DESCRIPTION OF THE FIGURES
[0019] Other objects and many attendant features of this invention
will be readily appreciated as the invention becomes better
understood by reference to the following detailed description when
considered in connection with the accompanying drawings
wherein:
[0020] FIG. 1 is a graph comparing the hydrogenation activity of
the hydrogenation catalyst of the present invention for sweet
aromatic feeds.
[0021] FIG. 2 is a graph comparing the hydrogenation activity of
the hydrogenation catalyst of the present invention for sour
aromatic feeds.
[0022] FIG. 3 is a graph of the data of Example 3 herein showing
the unexpected hydrogenation activity of a PtPd/MCM-41 catalyst
compared to a Pt-only/MCM-41 catalyst for a lube basestock
containing about 4.6 wppm sulfur and 122.5 mmol/kg of
aromatics.
[0023] FIG. 4 is a graph of the data of Example 4 herein showing
the unexpected hydrogenation activity of a PtPd/MCM-41 catalyst
compared to a Pt-only/MCM-41 catalyst for a lube basestock
containing about 69 wppm sulfur and 363 mmol/kg of aromatics.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Highly active hydrogenation catalysts, which are more sulfur
and/or nitrogen tolerant, are used herein in the production of
low-aromatics diesel production and other hydrogenation processes.
Such hydrogenation catalysts contain a hydrogenation component that
includes combination noble metal on a support having an inorganic,
porous crystalline phase material. Crystalline support materials
which may be used in the hydrogenation catalyst include the M41 S
group of mesoporous crystalline materials, which is described in
U.S. Pat. No. 5,102,643 and is exemplified by, but not limited to,
the MCM-41 and MCM-48 materials. MCM-41, which is described in U.S.
Pat. No. 5,098,684, is characterized by a microstructure with a
uniform, hexagonal arrangement of pores with diameters of at least
about 1.3 am. The preferred catalytic form of this material is the
aluminosilicate, although other metallosilicates may also be
utilized. MCM-48 has a cubic structure and is described in U.S.
Pat. Nos. 5,102,643 and 5,198,203; both of which, along with U.S.
Pat. No. 5,098,684, are incorporated herein in their entirety by
reference. U.S. Pat. No. 5,573,657 to Degnan et al. discloses
hydrogenation catalysts having similar support materials and is
incorporated herein by reference in its entirety.
[0025] The hydrogenation catalysts are particularly useful for
distillate hydrogenation. However, many other hydrogenation
processes can take the advantage of these high activity catalyst.
For example, hydrogenation of polyalphaolefin (PAO) for synthetic
lubricant base stock production is particularly attractive since
pore size of the support material can be varied widely to
accommodate the relatively bulky molecules of the lubricant base
stock. In addition, hydrogenation of vegetable oils and white oil
hydrogenation are other examples of bulky molecules that can be
processed. The catalysts of the present invention can also be used
for the hydrogenation of smaller molecules, such as benzene
hydrogenation or aromatic hydrogenation of sweet feed in the
second-stage of a hydrocracker.
[0026] A preferred catalyst of the present invention includes a
combination PtPd metal component and a MCM-41 support material. The
PtPd/MCM-41 catalyst can also produce high-quality jet and diesel
fuels, saturate polynuclear aromatics ("PNAs"), and reduce the
adverse effects by the undesirable PNAs. Hydrogenation Catalyst
[0027] The catalytic material includes an ultra-large pore size
crystalline phase as a support for the metal component of the
catalyst. This material is an inorganic, porous crystalline phase
material which can be characterized (in its calcined form) by an
X-ray diffraction pattern having at least one peak at a d-spacing
greater than about 18 Angstrom Units (.ANG.) with a relative
intensity of 100. The crystalline phase material has a benzene
sorption capacity of greater than 15 grains of benzene per 100
grams of the material at 50 torr and 25.degree. C. The preferred
form of the crystalline material is an inorganic, porous material
having a hexagonal arrangement of uniformly-sized pores with a
maximum perpendicular cross-section pore dimension of at least
about 13 .ANG., and typically within the range of from about 13
.ANG. to about 200 .ANG.. A preferred form of this hexagonal
crystalline composition, identified as MCM-41, has the
characteristic structure of hexagonally-arranged, uniformly-sized
pores of at least 13 .ANG. diameter. The crystalline phase material
exhibits a hexagonal electron diffraction pattern that can be
indexed with a d.sub.100 value greater than about 18 .ANG., which
corresponds to at least one peak in the X-ray diffraction pattern.
This material is described in detail in U.S. Pat. No. 5,098,684 to
Kresge et al.
[0028] The inorganic mesoporous crystalline material used as a
component of the catalyst has the following composition:
M.sub.n/q(W.sub.aX.sub.bY.sub.cZ.sub.dO.sub.h) (1)
[0029] wherein W is a divalent element, such as a divalent first
row transition metal, e.g. manganese, cobalt and iron, and/or
magnesium, preferably cobalt; X is a trivalent element, such as
aluminum, boron, iron and/or gallium, preferably aluminum; Y is a
tetravalent element such as silicon and/or germanium, preferably
silicon; Z is a pentavalent element, such as phosphorus; M is one
or more ions, such as, for example, ammonium, Group IA, IIA and
VIIB ions, usually hydrogen, sodium and/or fluoride ions; n is the
charge of the composition excluding M expressed as oxides; q is the
weighted molar average valence of M; n/q is the number of moles or
mole fraction of M; a, b, c, and d are mole fractions of W, X, Y
and Z, respectively; h is a number of from 1 to 2.5; and
(a+b+c+d)=1.
[0030] In one embodiment of the crystalline material defined by
equation (1), (a+b+c) is greater than d, and h=2. In another
preferred embodiment a and d=0, and h=2. The preferred materials
for use in making the present catalysts are the aluminosilicates
although other metallosilicates may also be used.
[0031] In the as-synthesized form, the support material has a
composition, on an anhydrous basis, expressed empirically as
follows:
rRM.sub.n/q(W.sub.aX.sub.bY.sub.cZ.sub.dO.sub.h) (2)
[0032] where R is the total organic material not included in M as
an ion, and r is the coefficient for R, i.e., the number of moles
or mole fraction of R.
[0033] The M and R components are associated with the material as a
result of their presence during crystallization, and are easily
removed or, in the case of M, replaced by post-crystallization
methods described below.
[0034] To the extent desired, the original M, e.g. sodium or
chloride, ions of the as-synthesized material of this invention can
be replaced in accordance with conventional ion-exchange
techniques. Preferred replacing ions include metal ions, hydrogen
ions, hydrogen precursor, e.g. ammonium, ions and mixtures of these
ions. Particularly preferred ions are those which provide the
desired metal functionality in the final catalyst. These include
hydrogen, rare earth metals and metals of Groups VIIA (e.g. Mn),
VIIIA (e.g. Ni), 1B (e.g. Cu), IVB (e.g. Sn) of the Periodic Table
of the Elements and mixtures of these ions.
[0035] The crystalline (i.e., having sufficient order to provide a
diffraction pattern such as, for example, by X-ray, electron or
neutron diffraction, following calcination with at least one peak)
mesoporous material may be characterized by its structure, which
includes extremely large pore windows, as well as by its high
sorption capacity. The term "mesoporous" is used here to indicate
crystals having uniform pores within the range of from about 13
.ANG. to about 200 .ANG., preferably from about 15 .ANG. to about
110 .ANG.. Since these pores are significantly larger than those of
other crystalline materials, it is appropriate to refer to them as
ultra-large pore size materials. As used herein, a "porous"
material is a material that adsorbs at least 1 gram of a small
molecule, such as Ar, N.sub.2, n-hexane or cyclohexane, per 100
grams of the solid.
[0036] The catalytic material can be distinguished from other
porous inorganic solids by the regularity of its large open pores,
whose pore size more nearly resembles that of amorphous or
paracrystalline materials, but whose regular arrangement and
uniformity of size (pore size distribution within a single phase
of, for example, .+-.25%, usually .+-.15% or less of the average
pore size of that phase) resemble more those of crystalline
framework materials such as zeolites. The preferred materials have
a hexagonal arrangement of large open channels that can be
synthesized with open internal diameters from about 13 .ANG. to
about 200 .ANG.. The term "hexagonal" is intended to encompass not
only materials that exhibit mathematically perfect hexagonal
symmetry within the limits of experimental measurement, but also
those with significant observable deviations from that ideal state.
A working definition of the term hexagonal, as applied to the
microstructure herein, would be that most channels in the material
are surrounded by six nearest neighbor channels at roughly the same
distance. Defects and imperfections will cause significant numbers
of channels to violate this criterion to varying degrees, depending
on the quality of the material's preparation. Samples which exhibit
as much as .+-.25% random deviation from the average repeat
distance between adjacent channels still clearly give recognizable
images of the present ultra-large pore materials. Comparable
variations are also observed in the d.sub.100 values from the
electron diffraction patterns.
[0037] The most regular preparations of the support material give
an X-ray diffraction pattern with a few distinct maxima in the
extreme low angle region. The positions of these peaks
approximately fit the positions of the hk0 reflections from a
hexagonal lattice. The X-ray diffraction pattern, however, is not
always a sufficient indicator of the presence of these materials,
as the degree of regularity in the microstructure and the extent of
repetition of the structure within individual particles affect the
number of peaks that will be observed. Indeed, preparations with
only one distinct peak in the low angle region of the X-ray
diffraction pattern have been found to contain substantial amounts
of the material in them. Other techniques to illustrate the
microstructure of this material are transmission electron
microscopy and electron diffraction. Properly oriented specimens of
the material show a hexagonal arrangement of large channels and the
corresponding electron diffraction pattern gives an approximately
hexagonal arrangement of diffraction maxima. The d.sub.100 spacing
of the electron diffraction patterns is the distance between
adjacent spots on the hk0 projection of the hexagonal lattice and
is related to the repeat distance a.sub.0 between channels observed
in the electron micrographs through the formula
d.sub.100=a.sub.0(3/2).sup.1/2. This d.sub.100 spacing observed in
the electron diffraction patterns corresponds to the d-spacing of a
low angle peak in the X-ray diffraction pattern of the material.
The most highly ordered preparations of the material obtained so
far have 20-40 distinct spots observable in the electron
diffraction patterns. These patterns can be indexed with the
hexagonal hk0 subset of unique reflections of 100, 110, 200, 210,
etc., and their symmetry-related reflections.
[0038] In its calcined form, the crystalline material may be
further characterized by an X-ray diffraction pattern with at least
one peak at a position greater than about 18 Angstrom Units
d-spacing (4.909.degree. 2.theta. for Cu K-alpha radiation) which
corresponds to the d.sub.100 value of the electron diffraction
pattern of the material, and an equilibrium benzene adsorption
capacity of greater than about 15 grams benzene/100 grams crystal
at 50 torr and 25.degree. C. (basis: crystal material having been
treated in an attempt to insure no pore blockage by incidental
contaminants, if necessary).
[0039] The equilibrium benzene adsorption capacity characteristic
of this material is measured on the basis of no pore blockage by
incidental contaminants. For instance, the sorption test will be
conducted on the crystalline material phase having any pore
blockage contaminants and water removed by ordinary methods. Water
may be removed by dehydration techniques, e.g. thermal treatment.
Pore blocking inorganic amorphous materials, e.g. silica, and
organics may be removed by contact with acid or base or other
chemical agents such that the detrital material will be removed
without detrimental effect on the crystal.
[0040] More particularly, the calcined crystalline non-layered
material may be characterized by an X-ray diffraction pattern with
at least two peaks at positions greater than about 10 .ANG.
d-spacing (8.842.degree. .theta. for Cu K-alpha radiation), at
least one of which is at a position greater than about 18 .ANG.
d-spacing, and no peaks at positions less than about 10 .ANG.
d-spacing with relative intensity greater than about 20% of the
strongest peak. Still more particularly, the X-ray diffraction
pattern of the calcined material of this invention will have no
peaks at positions less than about 10 .ANG. d-spacing with relative
intensity greater than about 10% of the strongest peak. In any
event, at least one peak in the X-ray diffraction pattern will have
a d-spacing that corresponds to the d.sub.100 value of the electron
diffraction pattern of the material.
[0041] The equilibrium benzene adsorption capacity is determined by
contacting the material of the invention, after dehydration or
calcination at, for example, about 540.degree. C. for at least
about one hour and other treatment, if necessary, in an attempt to
remove any pore blocking contaminants, at 25.degree. C. and 50 torr
benzene until equilibrium is reached. The weight of benzene sorbed
is then determined.
[0042] The ammonium form of the catalytic material may be readily
converted to the hydrogen form by thermal treatment (calcination).
This thermal treatment is generally performed by heating one of
these forms at a temperature of at least 400.degree. C. for at
least 1 minute and generally not longer than 20 hours, preferably
from about 1 to about 10 hours. While sub-atmospheric pressure can
be employed for the thermal treatment, atmospheric pressure is
desired for reasons of convenience, such as in air, nitrogen,
ammonia, etc. The thermal treatment can be performed at a
temperature up to about 750.degree. C. The thermally treated
product is particularly useful in the catalysis of certain
hydrocarbon conversion reactions and it is preferred that the
material should be in this from for use in the present
catalysts.
[0043] Catalyst Metal Component
[0044] The hydrogenation catalyst includes a metal as the
hydrogenation component. The hydrogenation component is provided by
a combination of metals. Noble metals of Group VIII, especially
palladium, platinum, rhodium and iridium can be used. For certain
applications, where sulfur and other contaminants such as
phosphorus are in low concentrations in the feedstock, e.g. sulfur
or phosphorous <10 ppm, a combination of palladium and platinum
is preferred. In addition to the synergistic benefit which a
combination of platinum and palladium provides with respect to
hydrogenation activity, the palladium metal provides resistance to
nitrogen poisoning.
[0045] The content of the metal component will vary according to
its catalytic activity. Thus, the highly active noble metals may be
used in smaller amounts. The present support materials for the
metal component are notable in that they are capable of including a
greater proportion of metal than previous support materials because
of their extraordinarily large surface area. The metal component
may exceed about 30 percent in a monolayer. The hydrogenation
component can be exchanged onto the support material, impregnated
into it or physically admixed with it. If the metal is to be
impregnated into or exchanged onto the mesoporous support, it may
be done, for example, by treating the zeolite with a palladium or
platinum metal-containing ion. Suitable platinum compounds include
chloroplatinic acid, platinous chloride and various compounds
containing the platinum amine complex. The metal compounds may be
either compounds in which the metal is present in the cation form
of the compound and compounds in which it is present in the anion
form of the compound. Both types of compounds can be used.
Palladium or platinum compounds in which the metal is in the form
of a cation of cationic complex, e.g., Pd (NH3).sub.4Cl.sub.2 or
Pt(NH.sub.3).sub.4Cl.sub.2 are particularly useful, as are other
anionic complexes such as the nitrate, vanadate and metatungstate
ions. Cationic forms of other metals are also very useful since
they may be exchanged onto the crystalline material or impregnated
into it.
[0046] Hydrotreating
[0047] The catalysts of the present invention can be used in a
variety of hydrotreating processes. For aromatic feedstocks, the
temperature of the hydrotreating step is from about 200.degree. to
850.degree. F. (about 93.degree. to 454.degree. C.), preferably
about 300.degree. to 750.degree. F. (about 150.degree. to
400.degree. C.), with the exact selection dependent on the
desulfurization desired for a given feed and catalyst. Because the
hydrogenation reactions that take place are exothermic, a rise in
temperature takes place along an adiabatic reactor. A temperature
rise of about 20.degree. to 200.degree. F. (about 11.degree. to
111.degree. C.) is typical under most hydrotreating conditions.
[0048] Since the feeds are readily desulfurized, low to moderate
pressures may be used for hydrogenation, typically from about 50 to
2000 psig (about 445 to 17800 kPa), preferably about 300 to 1000
psig (about 2170 to 7,000 kPa). Pressures are total system
pressure, reactor inlet. Pressure will normally be chosen to
maintain the desired aging rate for the catalyst in use. The space
velocity (hydrodesulfurization step) is typically about 0.5 to 10
LHSV (liquid hourly space velocity, hr'), preferably about 1 to 6
LHSV (hr.sup.-1). The hydrogen to hydrocarbon ratio in the feed is
typically about 500 to 5000 SCF/Bbl (standard cubic feet per
barrel)(about 90 to 900 n. 1.1.sup.-1), usually about 1000 to 2500
SCFIB (about 180 to 445 n. 1.1.sup.-1). The extent of the
desulfurization for feed pretreatment will depend on the initial
feed sulfur content and, of course, on the product sulfur
specification with the reaction parameters selected
accordingly.
EXAMPLE 1
[0049] The Pt/Pd on MCM-41 catalyst, which is one of the preferred
catalysts, can be prepared as follows. MCM-41 powder and Versal 300
Alumina powder are mulled for 5 minutes. Water is added to obtain a
total 40 wt. % solids content and the mixture is further mulled for
another 15 minutes. The mixture is extruded through a {fraction
(1/20)}" quadrulobe die and dried at 250.degree. F. overnight. The
dried extrudates are calcined at 1000.degree. F. in air using 5
cm.sup.3 air/mm/cm.sup.3 extrudate for a period up to 12 hours. The
calcined extrudates are drained of excess solution and washed with
10 volumes de-ionized or distilled water/volume extrudate followed
by overnight drying at 250.degree. F. After drying, the extrudates
are calcined at 1000.degree. F. in air using 5 cm.sup.3
air/mm/cm.sup.3 extrudate over a period of 3 hours.
[0050] The extrudates are co-impregnated to a 0.3 wt. % Pt/0.5 wt.
% Pd loading in a rotary vessel equipped with a spray nozzle, using
a Pt-tetraammine-nitrate and Pd-tetraammine-nitrate solution
equivalent to the extrudate incipient wetness volume. The
extrudates are then dried overnight at 250.degree. F. and calcined
at 680.degree. F. in air using 5 cm.sup.3 air/mm/min/cm.sup.3
extrudate for a period of 1 hour. Properties of the catalyst are
given in Table 1.
2TABLE 1 CATALYST PROPERTIES PROPERTY VALUE Platinum Content 0.32
wt. % Palladium Content 0.54 wt. % Surface Area 527 m.sup.2/gm Pore
Volume 1.027 cm.sup.3/gm
[0051] The final calcined catalyst includes a hydrogenation
component containing at least two noble metals. Prior to
pretreatment in the reactor, these metals can be present in the
catalyst in their elemental form or as their oxides, sulfides, or
mixtures thereof In a preferred embodiment, palladium and platinum
are used. The palladium and platinum are present in an amount
ranging from about 0.1 percent by weight to about 2.0 percent by
weight, preferably from about 0.2 percent by weight to about 1.5
percent by weight, and more preferably from about 0.3 percent by
weight to about 1.2 percent by weight based on the total weight of
the catalyst and calculated as oxide, for best results. Catalyst
metals concentrations outside of these total metals content ranges
have been found to be less efficient.
[0052] The weight ratio of elemental palladium to elemental
platinum generally ranges from about 10:1 to 1:10, preferably from
about 8:1 to 1:2, and more preferably from about 5:1 to 1:1 for
best results. It has been found that these ratio ranges provide the
most effective hydrogenation.
[0053] Several methods known to those skilled in the art can be
used for either deposing or incorporating the hydrogenation
component on the support using heat-decomposable salts of the noble
metals. For example, platinum and palladium can be impregnated onto
the support separately, or can be co-impregnated onto the support
using various aqueous impregnation solutions, including, but not
limited to, chloroplatinic acid, palladium chloride, tetraammine
palladium chloride and tetraammine platinum chloride.
EXAMPLE 2
[0054] The Pt/Pd on MCM-41 catalyst prepared in Example 1 was
tested against a reference catalyst. A commercial PtPd catalyst
supported on an aluminum-bound zeolite and having a high heat of
wetting and a high surface area (greater than 220 m.sup.2/g) was
used as the reference catalyst. Both catalysts were evaluated using
the same procedure. Both catalysts were dried at 500.degree. F. for
3 hours under a flow of nitrogen stream in a fixed-bed pilot unit.
After the drying, both catalysts were activated by hydrogen at
300.degree. F. and 500.degree. F. for 4 hours, each. The evaluation
was conducted at 350-600.degree. F., 1.3 LHSV, 700 psig, and 4000
SCF/Bbl of once-through hydrogen circulation rate.
[0055] A commercial diesel-range distillate was used as the feed
stock. This feed is preferred as the "sweet feed" since it is
almost free of sulfur (3 ppmw S) and nitrogen (<0.5 ppmw N). In
order to test the resistance (or tolerance) of the catalysts to
sulfur and nitrogen poisoning, the sweet feed was doped with
dibutyldisulfide and t-butylamine to 30 ppmw S and 10 ppmw N,
respectively to create a "sour feed." The properties of the sweet
feed and sour feed are shown below in Table 2.
3TABLE 2 FEED PROPERTIES PROPERTY SWEET FEED SOUR FEED Gravity,
.degree.API 23.70 23.70 Hydrogen, wt. % 11.93 11.93 Sulfur, ppmw 4
26 Nitrogen, ppmw <0.50 10 Aromatics, wt. % 46.80 26.80
Distillation -- -- (D2887), .degree. F. IBP 394.5 --
[0056] FIG. 1 hereof shows the test results for the sweet feedstock
using the PtPd/MCM-41 catalyst of the present invention and the
reference catalyst. The graph of the Remaining Aromatics in the
sweet feed by weight versus Temperature shows that the PtPd/MCM-41
catalyst is significantly more active than the reference catalyst
for hydrogenating the sweet feed. The PtPd/MCM-41 catalyst achieved
complete aromatic saturation at a temperature greater than
450.degree. F., while the reference catalyst never achieved
complete hydrogenation for the temperature range evaluated.
[0057] FIG. 2 shows the test results for the sour feedstock using
the PtPd/MCM-41 catalyst and the reference catalyst. The graph of
the Remaining Aromatics in the sweet feed by weight versus
Temperature shows that the PtPd/MCM-41 catalyst was more resistant
(or tolerant) to the poisoning by nitrogen and sulfur than the
reference catalyst. It is known that noble metal-containing
catalysts are sensitive to nitrogen and sulfur-containing compounds
and, therefore, in order for a hydrogenation catalyst to be
effective, it must exhibit a tolerance to these compounds. As shown
in FIG. 2, the PtPd/MCM-41 catalyst achieved the complete
hydrogenation of the sour feedstock at temperatures greater than
550.degree. F., but the reference catalyst did not achieve complete
hydrogenation.
[0058] Thus, while there have been described the preferred
embodiments of the present invention, those skilled in the art will
realize that other embodiments can be made without departing from
the spirit of the invention, and it is intended to include all such
further modifications and changes as come within the true scope of
the claims set forth herein.
EXAMPLE 3
[0059] Three catalysts were tested against a reference catalyst, a
0.9 wt. % Pt on MCM-41. The test catalyst were: a) 0.3 wt. % Pt/0.9
wt. % Pd on MCM-41; b) 0.9 wt. % Pt/0.1 wt. % Pd on MCM-41; and c)
0.15 wt. % Pt/0.45 wt. % Pd on MCM-41. The MCM-41 for all catalysts
was aluminum-bound. All catalysts were evaluated using the same
procedure. All catalysts were activated by subjecting them to a
nitrogen purge for 2 hours in a reaction vessel. While still
maintaining nitrogen flow the temperature was increased to
356.degree. F. at 36.degree. F./hr. The temperature was held at
356.degree. F. for three hours after which the catalysts were
cooled to 176.degree. F. and the nitrogen flow switched to hydrogen
flow at 89 cc/min. Hydrogen pressure was increased to 2000 psig and
the temperature increased to 500.degree. F. at 54.degree. F./hr.
The catalysts were then cooled to 302.degree. F. after which feed
was introduced. The feed was a lube basestock having the properties
set forth below.
4 Feed Properties Sulfur, wppm 4.6 Nitrogen, wppm <0.1 Density @
70.degree. C. 0.8361 VI 102.2 Aromatics, nimol/kg 122.5
[0060] The evaluation was conducted at a temperature from about
425.degree. F. to about 500.degree. F., 1.98 LHSV, 1810 psig, and
1990 SCF/Bbl of once-through hydrogen circulation rate. Table 3
below sets forth the hydrogenation data in terms of total aromatics
versus days on oil.
5TABLE 3 Total Aromatics vs. Days on Oil (DOS) for 4.6 wppm Sulfur
Feed Total Aromatics is measured in terms of mmol/kg 0.3% Pt/ 0.9%
Pt/ 0.15% Pt/ DOS 0.9% Pd 0.9% Pt 0.1% Pd 0.45% Pd 1.8 1.672 9.657
3.340 2.8 2.086 24.972 12.881 3.233 3.7 2.513 27.156 10.178 3.168
4.7 2.791 29.069 10.398 3.456 5.9 2.896 29.610 9.581 3.189 6.9
3.009 29.832 10.33 3.575 7.9 3.091 30.087 10.795 3.658 8.9 3.213
30.517 10.971 3.743 10.8 5.762 38.915 6.458 11.6 5.917 39.212 17.2
6.762 12.8 6.006 38.141 16.695 7.242 13.8 6.182 39.402 16.844 7.501
14.8 6.637 39.705 16.826 7.744 15.7 6.825 37.662 17.061 8.037 16.7
6.948 40.186 17.447 8.202 17.7 7.108 40.591 17.64 8.562 18.7 7.394
39.34 17.964 8.811 19.7 8.906 45.084 21.303 10.813 20.7 9.271
45.741 22.61 11.774 21.7 9.515 46.198 23.041 12.031 22.7 9.773
46.489 23.272 12.405
[0061] The data of the above table shows the unexpected improvement
in hydrogenation activity of a PtPd MCM-41 catalyst versus a Pt on
MCM-41 catalyst. This table also shows that the hydrogenation
activity of the catalyst improves dramatically even when only a
small amount (0.1 wt. % Pd) is included with the Pt.
EXAMPLE 4
[0062] The experimental procedure of Example 3 above was followed
except the feed was a lube basestock containing 69 wppm sulfur and
the catalyst containing 0.9 wt. % Pt/0.1 wt. % Pd was not used.
Table 4 below sets for the hydrogenation activity data for the
three catalaysts. FIG. 4 hereof presents this data in graphical
form. The feed used in this example has the properties set forth
below.
6 Feed Properties Sulfur, wppm 69 Nitrogen, wppm 3.4 Density @
70.degree. C. 0.8385 VI 106.9 Aromatics, mmol/kg 363.0
[0063]
7TABLE 4 Total Aromatics vs. Days on Oil (DOS) for 69 wppm Sulfur
Feed Total Aromatics is measured in terms of mmol/kg 0.3% Pt/ 0.15%
Pt/ DOS 0.9% Pd 0.45% Pd 0.9% Pt 1.5 22.265 46.325 71.561 2.5
20.481 12.099 74.463 4.3 23.305 193.097 5.5 22.962 26.99 193.608
6.5 22.269 28.593 200.442 7.5 23.099 28.936 196.984 8.5 22.647
29.609 194.203 9.5 22.766 29.961 198.801 11.4 14.236 17.307 128.269
12.5 13.743 16.693 124.886 13.5 13.889 16.805 126.216 15.5 44.796
60.287 263.854 16.3 46.539 66.37 267.564 17.3 47.411 63.83 268.334
19.5 43.127 58.501 247.01 20.5 43.13 59.792 246.463 21.5 43.24
56.186 242.45 23.5 16.351 21.062 24.5 15.217 19.945
[0064] The data in the above table shows the unexpected
hydrogenation activity of a PtPd on MCM-41 catalyst versus a Pt on
MCM-41 even with feeds containing relatively high levels of
sulfur.
* * * * *