U.S. patent application number 12/664474 was filed with the patent office on 2011-01-13 for enhanced process for the hydroconversion of heavy oils through ebullated-bed systems.
This patent application is currently assigned to ENI S.P.A.. Invention is credited to Giuseppe Bellussi, Nicoletta Panariti, Giacomo Rispoli, Lorenzo Tagliabue.
Application Number | 20110005976 12/664474 |
Document ID | / |
Family ID | 39764728 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110005976 |
Kind Code |
A1 |
Rispoli; Giacomo ; et
al. |
January 13, 2011 |
ENHANCED PROCESS FOR THE HYDROCONVERSION OF HEAVY OILS THROUGH
EBULLATED-BED SYSTEMS
Abstract
Process for the hydroconversion of heavy oils, selected from
crude oils, heavy crude oils, bitumens from tar sands, distillation
residues, distillation heavy cuts, distillation deasphalted
residues, vegetable oils, oils from coal and oil shale, oils from
the thermodecomposition of waste material, polymers, biomasses,
comprising sending the heavy oil to a hydroconversion area,
effected in one or more ebullated bed reactors, wherein hydrogen is
introduced, in the presence of a suitable heterogeneous, supported,
hydroconversion catalyst, in addition to a suitable hydrogenation
catalyst, nano-dispersed in said heavy oil, and sending the stream
coming from the hydroconversion area to a separation area, in which
the separated liquid fraction, containing the nano-dispersed
catalyst, is recycled to the ebullated bed reactor(s).
Inventors: |
Rispoli; Giacomo; (Rome,
IT) ; Bellussi; Giuseppe; (Piacenza, IT) ;
Panariti; Nicoletta; (Lecco, IT) ; Tagliabue;
Lorenzo; (Piacenza, IT) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
ENI S.P.A.
Rome
IT
|
Family ID: |
39764728 |
Appl. No.: |
12/664474 |
Filed: |
June 9, 2008 |
PCT Filed: |
June 9, 2008 |
PCT NO: |
PCT/EP2008/004680 |
371 Date: |
April 16, 2010 |
Current U.S.
Class: |
208/390 |
Current CPC
Class: |
C10G 65/12 20130101;
C10G 45/58 20130101; C10G 45/02 20130101; C10G 2300/1037 20130101;
C10G 3/56 20130101; C10G 47/00 20130101; C10G 2300/1014 20130101;
C10G 3/49 20130101; C10G 3/50 20130101; C10G 47/24 20130101; C10G
2300/4081 20130101; C10G 1/06 20130101; C10G 49/22 20130101; C10G
3/46 20130101; Y02P 30/20 20151101 |
Class at
Publication: |
208/390 |
International
Class: |
C10G 1/08 20060101
C10G001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2007 |
IT |
MI2007A001198 |
Claims
1. A process for the hydroconversion of heavy oils, selected from
crude oils, heavy crude oils, bitumens from tar sands, distillation
residues, distillation heavy cuts, distillation deasphalted
residues, vegetable oils, oils from coal and oil shale, oils from
the thermo-decomposition of waste material, polymers, biomasses,
comprising sending the heavy oil to a hydroconversion area,
effected in one or more ebullated-bed reactors, wherein hydrogen is
introduced, in the presence of a suitable heterogeneous, supported
hydroconversion catalyst, and also a suitable hydrogenation
catalyst, nano-dispersed in said heavy oil, and sending the stream
coming from the hydroconversion area to a separation area, in which
the liquid fraction separated, containing the nano-dispersed
catalyst, is recycled to the ebullated-bed reactor(s).
2. The process according to claim 1, wherein the separation area to
which the effluent stream from the hydroconversion area is sent, if
it is in liquid or mixed liquid/vapour phase, comprises one or more
atmospheric and/or vacuum distillation and/or one or more flash
steps, whereby the separation is effected of the different
fractions coming from the hydroconversion reaction, from the
distillation residue or from the liquid leaving the sole or last
flash step, which is recycled to reactor(s).
3. The process according to claim 1, wherein the separation area to
which the effluent stream from the hydroconversion area is sent, if
it is in vapour phase, comprises one or more high-pressure
separators.
4. The process according to claim 1, wherein a purging is effected
on the liquid fraction separated containing the nano-dispersed
catalyst, recycled to the ebullated-bed reactor(s).
5. The process according to claim 1, wherein the nano-dispersed
hydrogenation catalyst is based on Mo or W sulphide.
6. The process according to claim 5, wherein the nano-dispersed
hydrogenation catalyst can be formed in-situ starting from a
decomposable oil-soluble precursor, or ex-situ.
7. The process according to claim 5, wherein the nano-dispersed
hydrogenation catalyst additionally contains one or more other
transition metals.
8. The process according to claim 5, wherein the concentration of
the hydrogenation catalyst, nano-dispersed in the feedstock,
comprising the recycled stream, fed to the hydroconversion area,
defined on the basis of the concentration of metal(s) present,
ranges from 10 to 30,000 ppm.
9. The process according to claim 8, wherein the concentration of
the hydrogenation catalyst, nano-dispersed in the feedstock,
comprising the recycled stream, fed to the hydroconversion area,
ranges from 3,000 to 20,000 ppm.
10. The process according to claim 1, wherein the supported
heterogeneous hydrogenation catalyst is made up of a carrier and an
active phase consisting of a mixture of sulphides, one of which
deriving from a metal belonging to group VIB and at least one
deriving from a metal belonging to group VIII.
11. The process according to claim 10, wherein the metal belonging
to group VIB is molybdenum.
12. The process according to claim 10, wherein the metal belonging
to group VIII is selected from Ni and Co.
13. The process according to claim 10, wherein the active phase
consists of a mixture of sulphides, one of which deriving from
molybdenum and one deriving from Ni or Co.
14. The process according to claim 10 or 13, wherein the active
phase also consists of acidic sites introduced by either suitably
regulating the composition of the carrier or by adding a second
phase to the carrier.
15. The process according to claim 1, wherein the hydroconversion
reactions in ebullated beds take place at temperatures ranging from
360 to 480.degree. C. and pressures ranging from 100 to 200
atmospheres.
16. The process according to claim 2, wherein the distillation
steps are carried out at reduced pressure ranging from 0.001 to 0.5
MPa.
17. The process according to claim 17, wherein the distillation
steps are carried out at reduced pressure ranging from 0.01 to 0.3
MPa.
Description
[0001] The present invention describes an enhanced process for the
hydroconversion of heavy oils through ebullated-bed systems.
[0002] In processes used for the hydroconversion of heavy
hydrocarbon residues, the feedstock to be treated is put in contact
with hydrogen in the presence of a hydrogenation catalyst under
suitable temperature and pressure conditions. The conversion degree
for each single passage is never total. On the contrary, it is far
from being so, to the extent that, in industrial practice, it is
necessary for at least two reactors to be put in series in order to
obtain a conversion degree of 70%. The non-converted fraction of
the feedstock is inevitably destined for fuel oils or other
equivalent uses of little economical interest and at times creating
environmental problems.
[0003] In this area, the upgrading ebullated-bed technologies of
heavy residues have improved the pre-existing fixed-bed
technologies due to a higher efficiency of the catalyst, a better
thermal and material exchange. The supported heterogeneous
catalyst, in pellets having a suitable form and with millimetric
dimensions, is suspended in the hydrocracking reactor, mainly
regulating the liquid flow by means of the feeding flow-rate of the
feedstock and through a recycling pump of the liquid, inside or
outside the reactor. The flow-rates are regulated so that the
catalyst is positioned in a central area of the reactor, delimited
by a liquid seal at the inlet and outlet of the reactor. The
reaction is of the once-through type, with no recycling and the
reaction products are gas, naphtha, gas oil, vacuum gas oil (VGO)
and fuel oil. The typical reaction conditions of a hydrocracking
process with an ebullated-bed reactor, (see, for example, "Oil
& Gas Science and Technology, Rev. IFP, Vol. 55, 2000, Nr. 4,
p. 397") are indicated in the following table:
TABLE-US-00001 Reaction conditions standard preferred Residue
content 975.degree. F..sup.+ 50-100 80-100 in the feedstock (w %)
LHSV (liquid hourly space 0.1-1.0 0.2-0.5 velocity) hr.sup.-1
Reactor temperature .degree. F. 700-850 770-820 Partial pressure,
psig .sup. 500-3,500 2,500-3,000 H.sub.2 partial pressure
1,500-2,500 1,800-2,100 at the reactor outlet, psi Catalyst make-up
rate Ib/bbl 0.03-1.0 0.05-0.60
[0004] Even if the ebullated-bed technology has improved fixed-bed
technologies, it still has various restrictions, as it produces
fuel oil.
[0005] The catalyst used in ebullated-bed technologies normally
consists of alumina as binder and two active phases, one
responsible for the cracking activity and which can be introduced
by acting on the composition of the binder (for example, SiO.sub.2
or Al.sub.2O.sub.3 or blends thereof) or by adding a second
material having acidic sites (clay or zeolites, for example) and
one responsible for the hydrogen transfer activity, obtained by
functionalization of the carrier with a suitable mixture of
Mo(W)/Co(Ni)sulphides. This catalyst has a good hydrocracking
capacity and a sufficient capacity for activating the molecular
hydrogen and blocking the free radicals and formation of pitchy
products which can cause a rapid deterioration of the catalyst or
the obstruction of some of the plant sections. The limited hydrogen
activation capacity, however, does not allow the heaviest reaction
products to be recycled, thus limiting the conversion and causing
the undesired production of fuel oil. Furthermore, for the same
reasons, the concentrations of solid products (above all coke and
its precursors) in the reaction means, must be maintained at low
levels. In ebullated-bed processes, the solid hold-up (evaluate by
means of the HFT Hot Filtration Test technique) is lower than about
0.2% and frequent maintenance interventions are necessary for
removing the pitchy deposits formed in various areas of the
plant.
[0006] As an alternative to hydroconversion processes based on the
use of catalysts supported on fixed or ebullated beds, processes
have also been proposed using homogeneously dispersed catalysts in
the reaction means (slurry). These "slurry" processes are
characterized by the presence of catalyst particles having very
small average dimensions, micronic and/or sub-micronic and
uniformly dispersed in the hydrocarbon phase.
[0007] The catalyst normally used in slurry processes consists of a
nano-dispersion of laminar crystallites of molibdenite (MoS.sub.2),
produced in-situ in the reaction means, starting from an
oil-soluble compound fed together with the feedstock (see, for
example, IT-M12003A000692 and IT-MI2003A000693) or ex-situ, by the
interaction of a suitable molybdenum compound with H.sub.2S or an
organic sulphide. This material is highly efficient in the
activation of hydrogen and has optimum properties as a scavenger of
radicals (Applied Catalysis A: General, 204, 2000, p. 203). The
main function of this material, in fact, is to limit the formation
of resins or pitches from organic compounds having a low H/C ratio,
by blocking and limiting the diffusion of free radicals in the
reaction means, thus preventing the formation of coke. Molibdenite,
however, has a low cracking capacity and consequently in slurry
processes the cracking is mainly of a thermal nature (Applied
Catalyst A: General, 204, 2000, page 215).
[0008] Furthermore, the catalyst activity is hardly influenced by
the presence of carbonaceous residues coming from the degradation
of asphaltenes.
[0009] The possibility of enhancing ebullated-bed technologies by
adding a nano-dispersed catalyst based on MoS.sub.2 to the reaction
system, so that the concentration of the latter ranges from 10 to
500 ppm with respect to the feed-stock, has also been proposed in
literature (EP-546686 of Texaco Dev. Corp., US 2005/0241991 of
Headwaters Heavy Oil LLC). The other process conditions are similar
to those of ebullated-bed processes: there is no recycling of the
heavy fraction and therefore fuel oil is still present in the
reaction products, even if the quality of bottom hydrocracking has
improved in terms of density with respect to the starting case. In
once-through configurations, the concentration of molibdenite in
the reaction means must be kept low as, in the absence of
recycling, the catalyst is used up.
[0010] In conclusion, even if improvements have been observed with
respect to a typical ebullated-bed configuration, the main problems
of this technology have not been completely solved.
[0011] A process has now been surprisingly found, which can be
applied to heavy oils, selected from crude oils, heavy crude oils,
bitumen from tar sands, distillation residues, distillation heavy
cuts, deasphalted distillation residues, vegetable oils, oils from
coal and oil shale, oils from the thermo-decomposition of waste
material, polymers, biomasses, which is such as to substantially
overcome the problems so far found in ebullated-bed hydrocracking
processes for the conversion of heavy residues to distillates, by
modifying the typical scheme of an ebullated-bed process by adding
a recycling section to the reactor of the non-converted heavy
portion obtained from the bottom of a distillation column or other
liquid/vapour separation unit.
[0012] The process, object of the present invention, for the
hydroconversion of heavy oils, includes sending the heavy oil to a
hydroconversion area effected in one or more ebullated-bed reactors
into which hydrogen is introduced, in the presence of a suitable
heterogeneous, supported, hydroconversion catalyst and a suitable
hydrogenation catalyst, nano-dispersed in said heavy oil, and
sending the effluent stream from the hydroconversion area to a
separation area in which the liquid fraction separated, containing
the nano-dispersed catalyst, is recycled to the reactor(s).
[0013] The separation area to which the effluent stream from the
hydroconversion area is sent, whether it be in liquid or
liquid/vapour phase, can include one or more atmospheric and/or
vacuum distillation steps and/or one or more flash steps, whereby
the separation is effected of the different fractions coming from
the hydroconversion reaction from the distillation residue or from
the liquid coming from the sole or last flash step, which is
recycled to the ebullated bed reactor(s).
[0014] The separation area to which the effluent stream from the
hydroconversion area is sent, if in vapour phase, can include one
or more high pressure separators.
[0015] It is generally necessary to effect a purging on the
recycled stream in order to prevent the metal sulphides, produced
by the demetallation effect, from accumulating at excessively high
levels which could jeopardize the process processability (not only
in the hydrotreating reactor but also in the column bottoms,
separators, pumps and pipes). Obviously, during the purging the
catalyst is also unfortunately subtracted from the reaction cycle
and must therefore be continuously reintegrated accordingly.
[0016] The heterogeneous hydrogenation catalyst, typical of
ebullated beds, consists of a carrier and an active phase. The
carrier typically used is based on alumina, silica or mixtures
thereof having a suitable porosity. The active phase generally
consists of two components. The first, always present, is a mixture
of sulphides, one of which obtained from a metal belonging to group
VIB (preferably Mo) and at least one obtained from a metal
belonging to group VIII (preferably Ni or Co). The metals are
initially deposited on the carrier as oxides and are then
transformed into sulphides to be active in the reaction. The second
consists of acidic sites introduced either by suitably regulating
the composition of the carrier or by adding a second phase to the
carrier such as, for example, a zeolite or a clay.
[0017] The preferred active phase is that having as first or sole
component, a mixture of sulphides of which one derives from
molybdenum and one from Ni or Co.
[0018] The nano-dispersed hydrogenation catalyst, i.e. with a
dispersion of particles having micronic and/or sub-micronic
dimensions (nano-dispersion), added to the fresh feedstock in such
a quantity as to guarantee a sufficient activation degree of the
hydrogen in the reactor, is based on Mo or W sulphide and can be
formed in-situ starting from an oil-soluble, decomposable
precursor, or ex-situ and can possibly contain one or more
transition metals.
[0019] The make-up of the nano-dispersed catalyst is effected
together with the feed of the fresh feedstock, in order to
reintegrate the nano-dispersed catalyst discharged with the
purging.
[0020] The presence of an optimal concentration of the
nano-dispersed catalyst, in addition to limiting the formation of
resins or pitches, allows a better build-up of solids (determined
through the HFT technique) and limits the deterioration of the
supported, heterogeneous catalyst. In this way it is possible to
benefit from a higher cracking activity and, at the same time,
allow the recycling of the heaviest fractions to the reactor, thus
avoiding the production of fuel oil. The heterogeneous supported
catalyst is collected in the central section of the hydrocracking
reactor, as in traditional ebullated-beds, whereas the
nano-dispersed catalyst based on Mo or W sulphide, circulates with
the liquid through the various sections of the plant and is
recycled to the reactor. The solution allows a very high conversion
to be obtained together with a better quality of the products with
respect to both ebullated-bed reactors and slurry reactors.
[0021] This option allows all the synergies between the two
technologies (ebullated-bed and slurry systems) to be fully
exploited, thus providing a new and enhanced process which makes
use of the positive aspects of the supported heterogeneous
catalyst, typical of the ebullated-bed technology, and those of the
nano-dispersed catalyst typical of the slurry technology.
[0022] It is also possible to use the process according to the
present invention for the revamping of an existing ebullated bed
plant using the existing equipment and only effecting modifications
for the introduction of the dispersed, additional catalyst,
separating the products and recycling the heaviest products to the
hydrocracking reactor.
[0023] The ebullated-bed system can be carried out according to the
procedure and conditions typical of the known art (see, for
example, "Oil & Gas Science and Technology, Rev. IFP, Vol. 55,
2000, Nr. 4, p. 397").
[0024] The concentration of the transition metal in the
nano-dispersed catalyst, in the feedstock, including the recycled
stream, fed to the hydroconversion area, ranges from 10 to 30,000
ppm, preferably from 1,000 to 20,000 ppm.
[0025] The reactor(s) used is preferably run under a hydrogen
pressure, or a mixture of hydrogen and hydrogen sulphide, ranging
from 100 to 200 atmospheres, within a temperature range of 360 to
480.degree. C. The mixture of gas, consisting of hydrogen and
recycled gas, enters the reactor from above and is distributed
through the catalytic bed by means of a suitable distributor of a
specific design (grid plate).
[0026] The degree of purging required depends on the rate at which
coke and metal sulphides are produced and on the concentration of
solid matter in the reaction medium at the stationary state. By
operating according to the process described, the purging to be
effected can be maintained at a level lower than 10% with respect
to the feedstock fed.
[0027] The possible distillation steps of the separation section to
which the effluent stream from the hydroconversion zone is sent,
can be carried out at reduced pressure, preferably between 0.001
and 0.5 MPa, more preferably between 0.01 and 0.3 MPa.
[0028] A preferred embodiment of the present invention is now
provided with the help of FIG. 1 which, however, should not be
considered a limitation of the scope of the claim itself.
[0029] The fresh heavy feedstock (1) is mixed with the fresh
catalyst (2) and sent (3) to an ebullated-bed hydroconversion
reactor (E) in which a supported heterogeneous catalyst is
present.
[0030] A stream (4), containing the reaction product and the
nano-dispersed catalyst, leaves said reactor (E) and is sent to a
separation column (S) in order to separate the products (5) from
the liquid fraction containing the nano-dispersed catalyst (6)
which is recycled (7), after a purging (8), to the hydroconversion
reactor.
Example 1
[0031] Experimental tests were carried out in a pilot plant as
represented in FIG. 1. The ebullated bed reactors were operated in
a typical set of operating conditions. Three comparative tests were
conducted in the pilot plant: [0032] test A: the heavy bottom
stream from the vacuum distillation column was recycled to the
reactor and only a slurry catalyst was used. No other catalysts
were used during the test. [0033] test B: the heavy bottom stream
from the vacuum distillation column was recycled to the reactor and
two catalysts were used: a slurry catalyst and a commercial
catalyst in the ebullated beds. [0034] test C: the heavy bottom
stream from the vacuum distillation column was recycled to the
reactor and only a commercial catalyst was used in the ebullated
beds. The vacuum residue feed used for the experimental tests was
produced from the Basrah Light oil. The feed characterization is
reported in the table 1.
TABLE-US-00002 [0034] TABLE 1 characterization of the VR Basrah
Light Carbon wt % 83.45 Hydrogen wt % 10.07 Nitrogen wt % 0.38
Sulfur wt % 4.82 Asf C5 wt % 16.5 MCRT wt % 24.77 THFi wt % <0.1
Mo wppm 1795 Nichel wppm 45 Vanadium wppm 153 Density at Kg/m3
1031.4 15.degree. C. 5% .degree. C. 524 10% .degree. C. 540 20%
.degree. C. 562 30% .degree. C. 581 40% .degree. C. 598 50%
.degree. C. 615.5 60% .degree. C. 634 70% .degree. C. 653 80%
.degree. C. 674.5 90% .degree. C. 698.5 95% .degree. C. 711.5
Operating conditions, products yield and HDx performances (HDS,
HDN) are reported in table 2.
TABLE-US-00003 TABLE 2 operating conditions, products yield and HDx
per-formance test A test B Test C Operating Conditions Temperature,
.degree. C. 430 400 400 Total Pressure, barg 140 140 140 WHSV,
h.sup.-1 (1) -- 0.51 0.49 Mean Residence Time, h 4.3 3.9 4.1 Mo
Concentration .sup.(2) 1000 1000 -- Days On Stream 30 30 6 .sup.(3)
Products distribution (wt %) H2S 4.0 3.7 .sup.(4) C1-C4 8.9 9.6
.sup.(4) PI-170.degree. C. 9.3 6.9 .sup.(4) 170-350.degree. C. 33.6
44.3 .sup.(4) 350-500.degree. C. 44.1 35.5 .sup.(4) HDN 30.0 56.3
.sup.(4) HDS 74.0 88.0 .sup.(4) .sup.(1) Based on the ebullated bed
catalyst load .sup.(2) Concentration in the liquid feed to the
reactors .sup.(3) Test stopped due to the ebullated bed catalyst
deactivation .sup.(4) Products yield not determined for ebullated
bed catalyst continuous deactivation
[0035] Data produced in test B, using the slurry catalyst and the
commercial catalyst in the ebullated bed, shows a much higher
hydro-denitrogenation (HDN) and a higher hydrodesulfurization (HDS)
compared to the results from test A, obtained using only the slurry
catalyst. Furthermore, in test B was obtained a products yield
distribution similar to that of test A, and with higher atmospheric
diesel cut, but at lower operating condition severity, i.e. at a
reactor temperature 30.degree. C. lower.
* * * * *