Note: Descriptions are shown in the official language in which they were submitted.
1063~SS
This invention relates t~ a new process for desulfur-
izing petroleum hydrocarbons.
It is known in the art that the sulfur content of
sulfur-containing petroleum hydrocarbons can be reduced by
sub~ecting such hydrocarbons to hydr~genation in contact with
a catalyst. Among the catalysts which are effective for this
purpose are those which have been prepared from comp~unds of
metals of Group VI of the Periodic Table in combination with
compounds of metals of Group VIII of the Periodic Table. The
metals are normally dispersed on a carrler such as alumina or
silica-alumina. One method of impregnating these carrlers is
taught in U.S. Patent 3,232,887 and involves using phosphoric
acid stabilized solutions of the above-mentioned metals.
In the use of such catalysts for reducing the sulfur
content of petroleum hydrocarbon fractions containing sulfur,
the process is usually carried out under relatively high pres-
sures. The higher pressures required in extant processes im-
pose economic penalties. For example, hlgher pressure opera-
tion requires expensive, thick-walled vessels and increased
costs ~or higher pressure gas compressors. Furthermore, there
are greater hydrogen logses at high pressure due to unrecover-
able solution l!osses ln product llquid and due to chemical con-
sumptlon ln reactions unessentlal to hydrodesulfurlzatlon.
To reduce hydrogen usage, a desulnurlzatlon process
is needed in which slgnlflcant desulfurlzation of petroleum
frac~ions is accompllshed with a minimum o~ hydrogen presssure.
~; Thé inventlon provides a -process of reducing the sul-
~` fur content of sulfur-contalning petroleum hydrocarbons which
oomprise~ subJectlng petroleum hydrocarbon fraction containing
~ulfur to low pre~sure hydrogenation in contact with hydrogen
and a metal-molybdenum-phosphorus catalyst on a carrier wherein
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10630S5
the metal is from the group consisting of cobalt, nickel and
mixtures of cob~lt and nickel, the amount of sald metal present
in the catalyst being between 2-7% by weight calcùlated as the
- metal oxide expressed as (M0), 8-20% by weight molybdenum,
calculated as MoO3 and 2-10~ by weight phosphorus, calculated
as P205, under the following conditions:
B R. F. Max LHSV _
(A) up to 450500_700 50 up to 10 150
(B) 450 to 650600-750 200 up to 7 500
(C) 650 to 1100 600-800 400 ùp to 4 500
(D) over 1,100650-800 400 up to 2 500
wherein B.R. represents the boiling range of the petro~leum
fraction, T is the hydrogenation temperature, Max. psig. i8
the maximum hydrogen pressure in pounds per square inch gauge,
LHSV is the liqùid hourly space velocity and Min. SCF/B is the
minimum number of standard cubic ~eet Or hydrogen per ~2 gal-
lon barrel of said petroleum fraction and separating from said
contacting step said rraction having a reduced sulrur content.
The petroleum rractions containing sulrur to which
the process of the invention is particularly applicable are
the naphtha fraction having a boiling range up to 450F.,
usually in the range Or ?oo-450F.~ th~ middle distillate frac-
tion having a boiling range o~ 450-650F., the heavy gas oil
or vacuum gas oil rraction having a boiling range of 650-
1100F., and the reslduum fraction having a boiling range from
1000F. upward. These rr ctions correspond to (A), (B), (C)
and ~D), respectively, in`the foregoing statement Or the in-
vention.
The catalysts which are employed ln the practice Or
,
~ the invention are cobalt-molybdenum-phosphorus catalyst~,
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10~i30S5
nickel-molybdenum-phosphorus catalysts or catalysts prepared
from a mixture D~ these metals, which can be prepared ~s de-
scribed in U.S. 3,232,887, and which preferably contain the
catalytic elements impregnated on a carrier. These catalysts
should contain cobalt equivalent to 0.5-5% by weight CoO,
molybdenum equivalent to 8-20% MoO3, pre~erably 12.5-19% by
weight MoO3 ~nd phosphorus equivalent to 2-10% by weight P205,
pre~erably 2.5-7% by weight P205. A preferred catalyst contains
cobalt equivalent to 3% by weight CoO, molybdenum equivalent
to 13% by weight MoO3, and phosphorus equivalent to 3.25% by
weight P205. The nickel-molybdenum-phosphoru~ catalysts and
the m~xed catalyst of cobalt-nickel-molybdenum-phosphorus may
be obtained by substitutln~ickel, being calculated equiva-
B lent to NiO, for cobalt ~ in the above descriptions, eitherin whole or in p~rt.
The catalyst carriers can be any of the carriers
disclosed in U~S. 3,232,887 and the catalyst-carrier composite
may be in any suitable physical shape, for example, rod-like
or spherical. Alumina and mixtures of alumina and silica are
prererred carriers. Boehmitic alumina and gamma alumlna are
preferred types of carrlers.
The amount Or sulfur ln the petroleum fractlon to be
treated will vary with different petroleum fractlons but wlll
usually not exceed 5% by weight. Thus, ln the heavier rrac-
tion3 the amount Or sulfur might be around 1.5 to 4% by weight
while in lighter fractions it might be around 1% by weight.
From a practlcal standpolnt, lt 18 usually deslrable to reduce
the sulrur content to not more than 0.3~ by weight. It is a
~eature of thls inventlon that processes using catalyst ob-
talned rrom mlxtures of Group VI and VIII of the PerlodicTable supported on carrler~ and promoted by phosphorus unex-
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10~;305S
pectedly have been found to produce much superior desul~uriza-
tion performance at lower pressures than similar processes us-
ing catalysts of prior art without phosphorus while maintain-
ing catalyst activity for extended periods of time.
The invention will be illustrated but is not limited
by the following examples in which the quantities are stated in
parts by weight unless otherwise indicated.
EXAMPLE I
An aqueous ~olution containing cobalt, molybdenum
and phosphDrus was prepared as ~ollows: CoC03 (122 gms.) was
slurried in one liter of water. Concentrated 85~ H3P04 (67 ml.)
was added slowly with constant agitation. MoO3 (306 gms.) was
added and the reactants were heated to 190;F. This temperature
was held ~or 4 hours with constant stirring. The resulting
clear red solution was cooled to room temperature and the vol-
ume ad~usted to 1055 ml. to give a final concentration equiva-
lent to 290 gms/liter in MoO3.
The cobalt-molybdenum-phosphorus containing solution
was mixed well,with 25.6 pounds of dewatered boehmitic alumlna
gel (14~ A1203) and one gallon o~ water. The resulting slurry
was spray dried at 215 to 225F. The spray dried sample was
mulled with water to give a crumbly mass of 58% ~ree moisture.
The paste was extruded into 5/64" pills, dried at 300F. and
calcined at 1050F. to give a nominal 1/16" extrudate.
The resulting catalyst contained the equivalent o~
14.6% MoO3, 3.7~ CoO, and 3.1~ P205. The surface area was
362 m /gm. The pore volume was determined by nitrogen as 0.70
cm3/~m. The apparent bulk density (ABD) was 0.58 gms./ml.
EXAMPLE II
A catalyst was made from boehmitic alumina as in
Example I where the alumina was lmpregnated only with moiyb-
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1063055
denum oxide and cobalt carbonateO No phosphoric acid was used.
The resulting catalyst c~ntained the equivalent of
14.4% MoO3 and 3.4~ CoO. The surface area was 320 m2/gm. and
the pore volume was 0.491 cm3/gm.
EXAKPLE III
This catalyst was prepared using the technlque of
pore volume impregnation of a formed gamma alumina.
454 Gms. of MoO3 was slurried in 1.3 liters of water
an~ 100 ml. of H3P04 was added. This slurry was then heated
to 185F. and held at 185F. with stirring for one hour. After
this period, 185 grams of CoC03 was slowly added to the H3P04
and MoO3 slurry. This mixture was then held at 185F. with
stirring for an additional two hours and a clear solutlon was
obtained. The total volume of the solutiDn after it had been
allowed to cool to 90F. was 1890 ml. Th1s solution contalned
the equivalent o~ 240 gms. MoO3/liter Or solution, 56.7 gms.
CoO/liter of s~lution and 56 gms. P205/liter o~ solution.
The gamma alumina used in the preparation was pre-
pared by conventional means and w4s a sample of a commercially-
produced alumina containing silica. The size Dr the extrudatewas 1/16" and it had an inclpient wetness pore volume Or o.85
ml./gm.
The above solution was diluted and pore volume impreg-
nated onto the alumina to give a catalyst which, when analyzed,
- contained the equivalent of 12.3% MoO3, 2.9% CoO, and 2.5%
- P205
This cataly~t had a surrace arèa of 240 m2/gm, and had
a pore volume Or 0.55 cm3/gm.
~ IV -:
30 This catalyst was a commercial cobalt-molybdenum on
alumina catalyst. The gamma alumina was prepared in the same
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1063~55
manner as that o~ Example III. The catalyst can be prepared by
dlpping 227 gm of the calcined alumina pills in a solution
containing the equivalent of 50 gm/liter of MoO3 and 21 gm/liter
of CoO. The solution is prepared by dlssolving the appropriate
amounts o~ ammonium heptamolybdate and cobalt nitrate in water.
The catalyst used in the ~ollowing examples contained
the equivalent o~ 11.0% M~03 and 3.8% CoO. The ~ur~ace area was
B 3 m /gm and the pore volume was o.s6~ cm3/gm.
The activity Df the catalysts reported in the Examples
were measured using standard hydrodesulfurie~tion test pro-
cedures, equipment and feedstocks. Equal volumes of catalysts
were used in each case.
Results are expressed as a ratio of desul~urlz~tion
rate constants multiplied by 100, K = kte t/kr fe e x 100 to ~ -
give a percentage compari8on- The kreferenCe ln each ca8e
~or the non-phosphoru~ ~ntaining catalyst.
EXAMPLE_V
Te~ts were made to compare a commercial cobalt-
molybdenum-phosphorus catalyst prepared in a manner slmilar to
Example III with a catalyst containing substantially the same
amounts of cobalt and molybdenum without the p~osphorus, i.e.,
the catalyst o~ Example IV, in the desulfurization o~ a
19.5API gas oil which contained 3% sulfur by weight using a
; temperature Or 675F., an LHSV of 3.5, and a hydrcgen input of
25pO SCF/B as 100% hydrogen, and at various pressures.
The results are presented in graphic form ln Figure
} where përcent relatlve activity is plotted versus reactor
,. . . . . .
pres~sure. The re~erence catalyst is taken as 100%. It will
be noted that maximum re~ative activity is at approximately
350 p~lg hydrogen pressure.
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161 63~55
EXAMPLE VI
In order to demonstrate the activity ~tability over
a period of time, a long-term hydrodesulfurization te~t was
carried out using the phosphorus-containing catalyst described
in Example ~. The run condition8 were a reactor temperature
of 669F., oil flow rate of 1 LHSV, a 2500 SCF/~ hydrogen to
oil ratio and a pressure of 400 psig. These conditions gave
an initial 89% desulfurization. The vacuum gas oil feedstock
characterlstics were 2.8% sulfur, 20.0 API gravity and a boil-
lng range of 742-1065F.
The resultæ are presented in Figure 2 where the tem-
perature to produce a constant percentage desulfurization has
been calculated and plotted versus hours on stream. This
method of data presentation is chosen because in commercial
reactors temperature is the vsriable usually used in control-
ling the reactor to constant desulfurizatlon c~nditions. The
activlty expressed in terms of temperature required to maintain
a given desulfurization level was essentially constant over a
period of at least 1900 hours.
EXA~P_LE VII
A mid-western diesel oil having a gravity Or 32.4API,
a boiling range of 400-670F. and containing 1.27% by weight
sulfur was processed to reduce the sulfur content using the
same cat~lysts described in Example V at a hydrogenation tem-
perature of 650F. with a hydrogen input of 1500 SCF/B and an
LHSV of 3Ø Pressures over a range of 100 to 400 psig. were
studied. The results are presented graphically in Figure 3
where percent relative activity i9 plotted versus reactor pres-
sure. The reference, the non-phosphorus containing catalyst>
is taken as 100~ at each point.
It wlll be noted that the phosphorus-containlng
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:lC163~355
catalyst had a higher relative activity, particularly in hydro-
gen pressure ranges of 100 to 200 psig.
EXA~PLE VIII
A solution was prepared as follows: 54.7 gms. of
nickel nitrate hydrate was added to 30 mls. of water along
with 15.1 mls. of 85~ phosphoric acid. This solution was
added to 194 mls. o~ an ammonium heptamolybdate solution con-
taining the equivalent o~ 360 gm. MoO3/liter. The volume was
ad~usted to 275 mls. with water. This solution was pore
volume impregnated on 398.5 gms. of 1/16" gamma alumina ex-
trudate similar to that used in Example III.
After calcination, the catalyst c~ntained~the equiva-
lent of 14.9% MoO3, 2.97% NiO and 2.87~ P205. The sur~ace
area was 255 m2/gm and the pore volume was 0.54 cm3/gm.
The resultant catalyst gives superior results when
compared with a similar non-pho~phorus containing catalyst under
low pressure hydrogenation conditions herein described.
; In practicing the invention, generally speaking, the
lower limit of the LHSV is determined by practical considera-
tions. Usually in desulfuri~ing naphtha, the LHSV will be
within the range of 1-10; ln desul~urizing a middle distillate
the LHSV will be within the range of 2-7; in desulfurizing
heavy gas oil the LHSV will be within the range of 0.25-4. In
desulfurizing residua the LHSV will be within the range of 0.25-
~ 2. The lower the LHSV the greater the amount of sulfur that
; can be removed ~rom the oil. Depending on the nature o~ the
feedstock, tne pr~cess càn be carried out in vapor phase or
mixed liquid an~ vapor pha~e or in liquid phase. In general,
the heavier the feedstock, the higher the temperature.
While the process can be carried out with pure hy-
drogen, it is usually carried out with a hydrogen-containing
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1~63~)55
mixture in which the hydrogen occurs as a by-product Df other
operations.
It has further been found that a particularly useful
group of catalysts for desulfurizing a variety of feedstocks of
the type previously described is afforded wherein the catalyst
contains from 3.0-7.0% by weight of a mixture of nickel oxide
and cobalt oxide, calculated as NiO and CoO; 12.0-20.0% by
weight of molybdenum, calculated as MoO3 and 2.5-7.0% by
weight of phosphorus, calculated as P205.
The invention is particularly useful in making it
possible to desulfurize or reduce the sulfur content of various
types of oils at lower pressures and with a lower hydrogen -~
input.
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