U.S. patent application number 10/611105 was filed with the patent office on 2004-02-12 for process for reducing the naphthenic acidity of petroleum oils.
Invention is credited to Alvarenga Baptista, Claudia Maria de L., Bugueta, Paulo Cesar Peixoto, Cerqueira, Henrique Soares, Chamberlain Pravia, Oscar Rene, Gomes, Jefferson Roberto, Moreira, Elizabeth M..
Application Number | 20040026299 10/611105 |
Document ID | / |
Family ID | 30005470 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040026299 |
Kind Code |
A1 |
Chamberlain Pravia, Oscar Rene ;
et al. |
February 12, 2004 |
Process for reducing the naphthenic acidity of petroleum oils
Abstract
A process for reducing the naphthenic acidity of petroleum oils,
or their liquid fractions, is described, the process comprising a
thermal treatment of the petroleum oils, or their liquid fractions,
in the presence of an adsorbent the surface of which is covered by
high molecular weight carbon compounds. Preferred adsorbents are
the spent or coked FCC catalysts.
Inventors: |
Chamberlain Pravia, Oscar Rene;
(Rio de Janeiro, BR) ; Cerqueira, Henrique Soares;
(Rio de Janeiro, BR) ; Moreira, Elizabeth M.; (Rio
de Janeiro, BR) ; Alvarenga Baptista, Claudia Maria de
L.; (Rio de Janeiro, BR) ; Gomes, Jefferson
Roberto; (Rio de Janeiro, BR) ; Bugueta, Paulo Cesar
Peixoto; (Rio de Janeiro, BR) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Family ID: |
30005470 |
Appl. No.: |
10/611105 |
Filed: |
July 2, 2003 |
Current U.S.
Class: |
208/263 ;
208/299 |
Current CPC
Class: |
C10G 25/003 20130101;
C10G 25/00 20130101; C10G 2300/4012 20130101; C10G 2300/203
20130101; C10G 2300/4006 20130101 |
Class at
Publication: |
208/263 ;
208/299 |
International
Class: |
C10G 025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2002 |
BR |
0202552-3 |
Claims
What is claimed is:
1. A process for reducing the naphthenic acidity of a feedstock of
petroleum oils, or of their liquid fractions, the oil having being
desalted and dewatered, wherein the process comprises the following
steps: a) in a reactor, contacting the naphthenic, acidic petroleum
oils, or their liquid fractions, with an adsorbent, at a ratio of
adsorbent/petroleum oil (or petroleum liquid fractions) in the
range of from 0.1 to 5, at temperatures between 200.degree. C. and
500.degree. C., under pressures from of 0.01 to 0.3 MPag and
residence time between 1 second and 2 hours, so as to effect the
desired reduction in naphthenic acidity and obtain a treated
feedstock; b) on the treated feedstock of a), separating the used
adsorbent from the petroleum oil, or from its liquid fractions so
as to produce a treated, separated feedstock of reduced naphthenic
acidity; c) directing the treated, separated feedstock from b) to
further processing.
2. A process according to claim 1, wherein the ratio of
adsorbent/petroleum oil (or petroleum liquid fractions)/is in the
range of from 0.1 to 5.
3. A process according to claim 1, wherein the temperature of the
conversion reaction is between 250.degree. C. and 350.degree.
C.
4. A process according to claim 1, wherein the feedstock to be put
in contact with the adsorbent is a petroleum oil, or any petroleum
liquid fraction, of naphthenic acidity up to 5.0 mg KOH/g of
TAN.
5. A process according to claim 1, wherein the feedstock to be
processed is a petroleum oil the salt content of which is lower
than or equal to 2 Kg of salt per 160 thousand liters of
petroleum.
6. A process according to claim 1, wherein the feedstock to be
processed is a petroleum oil the water content of which is lower
than or equal to 0.5% by weight.
7. A process according to claim 1, wherein the feedstock to be
processed is a petroleum oil the water content of which is 0.1% by
weight.
8. A process according to claim 1, wherein the adsorbent features a
high surface area and its surface is covered by high molecular
weight carbon compounds.
9. A process according to claim 8, wherein the surface area of the
adsorbent is from 60 to 250 m.sup.2/g.
10. A process according to claim 9, wherein the surface area of the
adsorbent is from 100 to 200 m.sup.2/g.
11. A process according to claim 9, wherein the adsorbent is carbon
black.
12. A process according to claim 9, wherein the adsorbent is a
spent FCC catalyst.
13. A process according to claim 9, wherein the adsorbent is a
coked FCC catalyst.
14. A process according to claim 9, wherein the adsorbent is
previously treated with an alkaline solution, where the
concentration of the alkaline base is in the range of from 5 to 15%
by weight, in a mass ratio of alkaline base/mass of the catalyst of
from 0.05 to 0.5 and, is further dried at temperatures between 100
and 120.degree. C., for 10 to 16 hours.
15. A process according to claim 15, wherein the base of the
alkaline solution is a metal hydroxide of group IA.
16. A process according to claim 15, wherein the alkaline base of
the alkaline solution is a metal hydroxide of group IIA.
17. A process according to claim 15, wherein the alkaline base of
the alkaline solution is ammonium hydroxide.
18. A process according to claim 15, wherein the alkaline base of
the alkaline solution is a mixture of metal hydroxide of group IA,
IIA and ammonium hydroxide, in any amount.
19. A process according to claim 1, wherein the separation of the
used adsorbent and the treated petroleum oil is carried out by
means of a liquid/solid separation system.
20. A process according to claim 19, wherein the liquid/solid
separation system is a cyclone, a hydrocyclone or a centrifuge.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a process for reducing the
naphthenic acidity of petroleum oils, or of their liquid fractions,
by thermal treatment, in the presence of an adsorbent.
[0002] More particularly, the invention relates to a process which
promotes the conversion of naphthenic acids present in petroleum
oils, or in their liquid fractions, to CO, CO.sub.2 and H.sub.2O,
by means of catalytic conversion, in order to make these products
less harmful to the equipment which are designed to process it.
[0003] Further the invention reduces the viscosity of petroleum
oils by decomposing the carboxylic moieties of the naphthenic acids
and thus minimizes the possible occurrence of one of the factors
which leading to increased petroleum oil viscosity as a consequence
of the interaction among its own carboxylic moieties.
BACKGROUND OF THE INVENTION
[0004] In view of the fact that recently discovered petroleum oils
are increasingly heavy and of high naphthenic acidity, besides
being very viscous has created a challenge to be met by the
petroleum industry. Petroleum oils having high content in organic
acids are strongly corrosive to the equipment used in the
extraction, transportation and processing of oil and consequently,
any reduction in naphthenic acidity would alleviate
corrosion-associated problems.
[0005] Those kinds of petroleum oils and their respective liquid
fractions having high contents of organic acids are particularly
detrimental to the refineries process equipment, especially when
those raw materials are used in distillation towers, where high
corrosion levels and incrustations have been observed. In Brazil,
petroleum oils from the Campos Basin, like Marlin, Albacora e Siri
have shown such characteristics and their organic acids are
normally naphthenic acids.
[0006] U.S. Pat. No. 6,054,042 teaches that naphthenic acidity can
be expressed as Total Acid Number (TAN) which means quantity of
milligrams of KOH required to neutralize one gram of oil. The
analytical method used for the measurements is the D-664 ASTM
Method.
[0007] Determinations made by infrared spectroscopic analysis allow
to estimating the naphthenic acidity contents by measuring the area
under the carboxyl characteristic band between 1700 and 1750
cm.sup.-1. By combining results from both methods, it is possible
to obtain an approximate measure of how much acidity is due to
carboxylic acids.
[0008] Several approaches to reduce naphthenic acidity in petroleum
oils have been adopted in the art.
[0009] In order to minimize the problem, one of those is directed
to the use of a mix of petroleum oils of different acidity
levels.
[0010] Another one uses corrosion inhibitor additives to control
the acidity. US patents U.S. Pat. No. 5,182,013 and U.S. Pat. No.
4,647,366 teach different types of these inhibitors.
[0011] Acidity reduction can yet be obtained by treating oil with
basic solutions of NaOH and KOH, as taught in US patent U.S. Pat.
No. 4,199,440. However, this method demands the use of strong basic
solutions and shows a critical point, which is the formation of
hard-to-break stable emulsions. In order to avoid such
emulsification problems, an alkaline detergent treatment, based on
calcium sulfonate or naphtenate addition is claimed in U.S. Pat.
No. 6,054,042.
[0012] In U.S. Pat. No. 6,258,258 the use of anhydrous solutions of
ammonia is described. In U.S. Pat. No. 6,281,328 polymeric amine
solutions, as polyvinyl pyridine are indicated for the same use.
U.S. Pat. No. 4,300,995 teaches an oil treatment with a basic
solution of quaternary hydroxides, such as tetramethyl ammonium
hydroxide, in alcohol or water.
[0013] WO 01/79386 teaches the use of a basic solution and metals
from group IA, IIA and ammonia hydroxides together with a transfer
agent, as the quaternary non-basic salts and polyethers.
[0014] U.S. Pat. No. 6,190,541 teaches the use of bases from
hydroxides and phosphates with an alcohol.
[0015] According to U.S. Pat. No. 6,086,751, acidity may be reduced
by thermal treatment. The oil is initially flashed to effect water
removal and after that, the effluent is heated to temperatures
between 340 and 420.degree. C., pressures below 0.7 MPag and
reaction times up to 2 hours.
[0016] According to U.S. Pat. No. 5,985,137, naphthenic acidity and
sulfur contents of petroleum oils are reduced by reacting with
alkaline earth metal oxides, which produce neutralized compounds
and alkaline earth metal sulfides. Temperatures must be higher than
(or: in excess of) 150.degree. C. to remove carboxylic acids and
higher than 200.degree. C. to produce sulfide salts. The applied
pressure should be high enough to keep the oil in the liquid
state.
[0017] Generally, methodologies to reduce the naphthenic acidity
make use of thermal treatments that proceed at temperatures around
400.degree. C. and pressures about 1 MPag. However, such
methodologies depend on alkaline solution additions to neutralize
that acidity. In such cases, the necessity of additional use of
surfactants, to control emulsification problems, render the
operation more expensive and harder to process. Surfactants are
highly expensive chemical products.
[0018] Therefore, in spite of the research effort directed to the
problem of minimizing naphthenic acidity in petroleum oils, the
technique still needs a process directed to reducing the level of
naphthenic acids to acceptable grounds, such a process, based on a
thermal treatment in the presence of coked (spent) Fluid Catalytic
Cracking (FCC) catalysts being described and claimed in the present
invention.
SUMMARY OF THE INVENTION
[0019] The present invention relates to a process for reducing the
naphthenic acidity of petroleum oils, or of their liquid fractions,
the oil having being desalted and dewatered, wherein the process
comprises the following steps:
[0020] a) in a reactor, contacting the feedstock of naphthenic
acidic petroleum oil, or its liquid fractions, with an adsorbent,
at a ratio of adsorbent/petroleum oil (or its liquid fractions) in
the range of 0.1 to 5, at temperatures between 200.degree. C. and
500.degree. C., under pressures from 0.01 to 0.3 MPag and residence
time between 1 second and 2 hours, so as to effect the desired
reduction in naphthenic acidity and obtain a treated feedstock;
[0021] b) on the treated feedstock obtained in a), separating, with
the aid of a liquid/solid separation system, the used adsorbent
from the petroleum oil, or from its liquid fractions, which had
their naphthenic acidity reduced so as to produce a treated,
separated feedstock;
[0022] c) directing the treated, separated feedstock from b) to
further processing.
[0023] Therefore, one objective of the present invention is a
process to promote the conversion of naphthenic acids present in
petroleum oils, or in their liquid fractions, to CO, CO.sub.2 and
H.sub.2O, by contacting said feedstock with FCC spent or coked
catalysts.
[0024] Additionally, another objective of the present invention is
a process that provides a viscosity reduction of the crude
petroleum oils processed according to said process.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Recent research developed by the Applicant has been directed
to evaluating the effect of thermal treatment in petroleum oils and
in their liquid fractions which have considerable values of
naphthenic acidity, in the presence of an adsorbent covered with
high molecular weight carbon compounds.
[0026] Among the adsorbents useful for the purposes of the
invention is a coked catalyst used in Fluid Catalytic Cracking
(FCC) processes, the adsorbent being covered by a superficial
deposit of petroleum coke which has reduced its catalytic activity
by 50 to 70% from the original one. Such deposit is formed by
thermal and catalytic mechanisms and is made up by heteroatom-rich
polycondensed aromatic molecules and asphaltene structures, which
become adherent to the catalyst surface. These molecular
structures, as well as the chemical nature of the petroleum coke,
promote the interaction between hydroxyl group-bearing molecules of
petroleum, with the consequence that at least, 80% of the
naphthenic acids present in the feedstock are reduced, without no
other additional chemical treatment, even though at the low
temperatures and pressures used in the experiments.
[0027] Thus it is clear that the state-of-the-art technique can be
improved if a process is provided which is able to maximize
reduction in the naphthenic acidity of petroleum oil, or of its
liquid fractions, dispensing with the use of alkaline solutions and
thus avoiding additional use of chemical products.
[0028] The present invention reduces the naphthenic acidity of
petroleum oils and of their liquid fractions by promoting the
decomposition of those naphthenic acids to CO, CO.sub.2 and
H.sub.2O by means of a thermal treatment effected in the presence
of FCC spent or coked catalysts, among other adsorbents, which
eliminates the problems caused by the utilization of alkaline
solutions and, additionally, allows the reduction of the refinery
residue inventory.
[0029] Adsorbents suitable to promote the desired effect of
naphthenic acidity conversion are those of large specific area and
high content of surface carbon like, for example, carbon black, or
FCC spent or coked catalyst, but not limited to them. Specific
areas of the spent or coked catalyst of FCC, suitable to be used in
the treatments described herein are in the range of from 60 to 250
m.sup.2/g, but preferably of from 100 to 200 m.sup.2/g. So, any
carbonated material supposed to be able to promote a chemical or
physical interaction similar to that pointed out in the present
specification can be used for the purposes of the invention.
[0030] The use of the carbonated material, supported or not by a
catalyst matrix, allows, based on Van der Waals forces, the action
of the said carbonated material on petroleum, or on its liquid
fractions, as an adsorbent surface which attracts and retains
carboxylic acids present therein and thus naphthenic acidity is
reduced.
[0031] In the case of the coked catalyst, the said adsorption
phenomenon occurs by chemical interactions between carboxyl
functional groups of the oil product and the heteroatoms present in
considerable concentrations in the said coked catalyst.
[0032] The use of the spent FCC catalyst according to the invention
dispenses with the need of any alkaline solutions to neutralize the
naphthenic acids, eliminating the presence of an aqueous phase
which brings some drawbacks by producing stable emulsions in the
presence of oil, such emulsions being normally very hard to break
down.
[0033] The catalytic conversion reactions of the carboxylic acids
yield CO, CO.sub.2 and water vapor; in such a way, it becomes
necessary to provide ventilation or a purge system using inert
vapors such as nitrogen, natural gas or light hydrocarbon
vapors.
[0034] In practice, the present invention may require or not that
the feedstock to be processed be submitted to a desalting process
before being flashed to remove water and possible light
fractions.
[0035] Usually, desalting is required in petroleum oils of salt
contents higher than 2 Kg of salt per 160 thousand liters of
petroleum. The desalting is a common process and well-known among
those skilled in the refining art.
[0036] The flashing step is normally required because water is
almost always present in oil and its content should be strongly
reduced. Besides, in many cases, the extremely heavy petroleum oils
have to be diluted with naphtha either in order to allow
transportation, or to improve pumpability.
[0037] During the flashing step, gaseous streams of C.sub.4 light
fraction, water and any diluents are vaporized in the flashing
condition which normally reaches temperatures of from 120.degree.
C. to 370.degree. C. and pressures of from the atmospheric to 1.7
MPag. Flashing time is usually determined by the necessity of a
substantial reduction in the water present in the petroleum which
has to be decreased to levels as low as 0.5% by weight, preferably
lower than 0.1% by weight.
[0038] As for the desalting process, the flashing procedures are
identically well-known to those skilled in the refining art.
[0039] The temperature, the pressure and the reaction time to be
practiced in the present invention depend upon the nature of the
petroleum oil to be treated, the naphthenic acidity level of that
petroleum oil and space velocity used in the reactor.
[0040] Normally, the conversion reaction is done at temperatures
between 200.degree. C. and 500.degree. C., but, preferably between
250.degree. C. and 350.degree. C., under pressures of from 0.01 to
0.3 MPag and residence time between 1 second and 2 hours.
[0041] The ratio of adsorbent/petroleum oil or its liquid fractions
is in the range of 0.1 to 5, more preferably in the range 1 to
5.
[0042] The thermal treatment in the presence of the adsorbents
mentioned herein makes possible to reduce the naphthenic acidity of
petroleum oils, or of their liquid fractions, from TAN figures as
high as 5.0 mg of KOH/g of oil to values lower than 0.5 mg of
KOH/g, dispensing with the use of high pressures such as pressures
over 1.0 MPag.
[0043] The liquid/solids separation systems useful to effect the
separation of the adsorbents from the treated feedstock are those
commonly described in the literature as, for example, the cyclones,
or hydrocyclones, or centrifuges that are systems well known to
those skilled in the refining art.
[0044] Further interpretations about the nature and mechanisms of
the phenomena herein described do not modify the practical meaning
of the novelty brought by the present invention which will be now
illustrated by the following Examples which should not be
considered as limiting it.
EXAMPLE 1
[0045] A sample of Albacora oil, having a TAN of 1.7 mg KOH/g was
fed to a tubular reactor and submitted to a thermal treatment at
temperatures of 250, 350, 400 e 450.degree. C., in the presence of
a matrix covered by high molecular weight carbon compounds (spent
FCC catalyst of specific area of 155 m.sup.2/g), during 1 hour and
under pressure of 0.01 MPag. The test results are shown in Table 1
below.
1TABLE 1 Retention and Total Base decarboxyla- Number Temperature,
Ratio of tion, by IR (1) (TAN), mg Tests .degree. C. Adsorbent
adsorbent/oil (%) KOH/g 1 250 Spent FCC cat. 5 94 0.3 2 350 Spent
FCC cat. 5 82 0.5 3 400 Spent FCC cat. 5 74 0.6 4 450 Spent FCC
cat. 5 85 0.3 5 350 Spent FCC cat. + 5 82 0.5 NH.sub.4OH 6 350
Inert matrix 5 22 1.5 7 350 Spent FCC cat. 0.1 78 1.4 8 350 Spent
FCC cat. 1 77 1.0 Obs.: (1) infrared
[0046] Based on results of the retention and decarboxylation column
of TABLE 1 above it is concluded that TAN reduction occurs because
there was a retention and decarboxylation of the naphthenic acids,
in the range of 74 to 94%, for all temperatures.
EXAMPLE 2
[0047] Another sample of the same petroleum of Example 1 was
thermally treated in a tubular reactor, at a temperature of
350.degree. C., for 1 hour, under a pressure of 0.01 MPag, in the
presence of a spent FCC catalyst that had previously been submitted
to a treatment with a solution of ammonium hydroxide (10% by
weight) in such a way that a mass ratio of NH.sub.4OH/mass of
catalyst of 0.1 was obtained. After the treatment, the catalyst was
dried at 120.degree. C., for 16 hours. Number 5 test, in Table 1
above, shows, in the retention and decarboxylation for IR column,
the result obtained in the effluent of this experiment. When that
result is compared with the result of number 2 test, it can be
observed that the catalyst treatment did not affect the efficiency
of carboxyl removal.
EXAMPLE 3
[0048] Another sample of the same petroleum of Example 1 was
thermally treated in a tubular reactor, at a temperature of
350.degree. C., for 1 hour, under pressure of 0.01 MPag, in the
presence of an inert matrix made up of silicon spheres of 70 micron
average size of and without carbon on their surface. Test number 6,
in TABLE 1 above, shows the TAN results obtained in the effluent of
the experiment. When that result is compared with the result
obtained in test 2, it can be concluded that the presence of the
spent catalyst is paramount for a successful treatment.
[0049] Therefore, it is clear that the present invention promotes
the optimized removal of carboxylic acids from petroleum oils
relative to other state-of-the-art methods, since not only such
removal is more selective as the treatment products are gases or
vapors that can be more easily withdrawn from the reactor than the
neutralization products generated in prior processes.
[0050] Besides that, state-of-the art thermal treatments are not
able to make such selective conversion and are supposed to promote
secondary oxidation or cracking reactions which generate
undesirable by-products, such as olefins, which are detrimental to
the quality of valuable streams, such as naphtha and diesel oil,
resulting from further processing of oil.
* * * * *