U.S. patent application number 10/336948 was filed with the patent office on 2003-09-25 for use of hydrogen to regenerate metal oxide hydrogen sulfide sorbents.
Invention is credited to Baird, William C. JR., Brown, Leo D., Chen, Jingguang G., Ellis, Edward S., Klein, Darryl P., McVicker, Gary B., Touvelle, Michele S., Vaughan, David E. W..
Application Number | 20030178343 10/336948 |
Document ID | / |
Family ID | 28046677 |
Filed Date | 2003-09-25 |
United States Patent
Application |
20030178343 |
Kind Code |
A1 |
Chen, Jingguang G. ; et
al. |
September 25, 2003 |
Use of hydrogen to regenerate metal oxide hydrogen sulfide
sorbents
Abstract
A process to regenerate a spent hydrogen sulfide sorbent
comprised of a sorbent metal selected from Fe, Ni, Co, and Cu on a
refractory oxide support using hydrogen gas. The sorbent metal
component may be mono- or multi-metallic in nature, and preferably
comprise Ni and/or Co. If desired, secondary metals may be
incorporated to increase regeneration efficiency and/or capacity.
Other additives suppress hydrocarbon cracking.
Inventors: |
Chen, Jingguang G.;
(Hockessin, DE) ; Brown, Leo D.; (Baton Rouge,
LA) ; Baird, William C. JR.; (Baton Rouge, LA)
; McVicker, Gary B.; (Califon, NJ) ; Ellis, Edward
S.; (Fairfax, VA) ; Touvelle, Michele S.;
(Centreville, VA) ; Klein, Darryl P.; (Ellicott
City, MD) ; Vaughan, David E. W.; (State College,
PA) |
Correspondence
Address: |
EXXONMOBIL RESEARCH AND ENGINEERING COMPANY
P.O. BOX 900
1545 ROUTE 22 EAST
ANNANDALE
NJ
08801-0900
US
|
Family ID: |
28046677 |
Appl. No.: |
10/336948 |
Filed: |
January 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10336948 |
Jan 6, 2003 |
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09620864 |
Jul 21, 2000 |
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09620864 |
Jul 21, 2000 |
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09326827 |
Jun 7, 1999 |
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6221240 |
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09326827 |
Jun 7, 1999 |
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08918641 |
Aug 22, 1997 |
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5935420 |
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60024737 |
Aug 23, 1996 |
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Current U.S.
Class: |
208/213 ;
208/216R; 208/217; 208/244; 502/53 |
Current CPC
Class: |
C10G 45/10 20130101;
B01J 20/0225 20130101; B01J 20/06 20130101; B01J 20/3433 20130101;
B01J 23/94 20130101; C10G 45/62 20130101; C10G 65/043 20130101;
C10G 45/04 20130101; B01J 20/3458 20130101; B01J 20/103 20130101;
B01J 23/89 20130101; B01J 20/08 20130101; C10G 25/003 20130101 |
Class at
Publication: |
208/213 ; 502/53;
208/216.00R; 208/217; 208/244 |
International
Class: |
C10G 045/04; C10G
045/06; C10G 045/10 |
Claims
1. A process for regenerating a hydrogen sulfide sorbent
comprising: providing a spent hydrogen sulfide sorbent comprised of
an effective quantity of a sorbent metal selected from the group
consisting of Fe, Ni, Co, Cu, and polymetallics thereof on a metal
oxide support, said hydrogen sulfide sorbent having a level of
sulfur defining a first cycle capacity for absorbing hydrogen
sulfide; and exposing said spent hydrogen sulfide sorbent to a gas
comprising a regenerating concentration of hydrogen under
conditions effective for said hydrogen to regenerate said spent
hydrogen sulfide sorbent, thereby producing a regenerated
sorbent.
2. The process of claim 1 wherein said sorbent metal is selected
from Ni and Co.
3. The process of claim 2 wherein said conditions comprise a
temperature from about 100.degree. C. to about 700.degree. C.
4. The process of claim 3 wherein said conditions comprise a
temperature from about 250.degree. C. to about 600.degree. C.
5. The process of claim 2 wherein said spent hydrogen sulfide
sorbent contains a regeneration rate enhancing amount of a noble
metal selected from Group VIII of the Period Table of the elements,
wherein said regeneration rate enhancing amount reduces said
regenerated capacity by about 50% or less.
6. The process of claim 5 wherein said regeneration rate enhancing
amount reduces said regenerated capacity by about 30% or less.
7. The process of claim 5 wherein the noble metal is at least one
of Ir, Pt, Pd, and Rh.
8. The process of claim 7 wherein two noble metals are present.
9. The process of claim 5 wherein said regeneration rate enhancing
amount ranges from about 0.01 wt. % to about 10 wt. %.
10. The process of claim 1 wherein the sorbent further comprises at
least one hydrocracking suppressor metal selected from Group IB,
Group IVA, and Group VIA of the Periodic Table in a suppressing
quantity sufficient to suppress hydrocracking.
11. The process of claim 10 wherein said hydrocracking suppressor
metal is (i) at least one of Cu, Ag, Au, Sn, and Pb, and the
suppressing quantity ranges from about 1 wt. % to about 10 wt. %,
or (ii) at least one Group VIA element, and the suppressing
quantity ranges from about 0.01 wt. % to about 2 wt. %.
12. The process of claim 1 wherein the regenerated sorbent has a
capacity for absorbing hydrogen sulfide ranging from about 5% to
about 100% of the first cycle capacity.
13. A desulfurization process comprising: (a) contacting a
hydrocarbon containing sulfur with a catalytically effective amount
of a catalyst system under catalytic hydrodesulfurization
conditions, the catalyst system being comprised of: (i) a
hydrodesulfurization catalyst containing at least one of Mo, W, Fe,
Co, Ni, Pt, Pd, Ir, and Rh; and comprising at least one of: (ii) a
hydrogen sulfide sorbent containing at least one sorbent metal
selected from Fe, Co, Ni, and Cu, on a metal oxide support, said
hydrogen sulfide sorbent comprising a level of sulfur defining a
first cycle capacity for absorbing hydrogen sulfide, said
contacting producing at least a desulfurized product and a spent
hydrogen sulfide sorbent; and then (b) exposing said spent hydrogen
sulfide sorbent to a gas comprising a regenerating concentration of
hydrogen under conditions effective for said hydrogen to regenerate
said spent hydrogen sulfide sorbent, producing a regenerated
sorbent.
14. The process of claim 13 wherein said sorbent metal is selected
from at least one of Ni and Co.
15. The process of claim 13 wherein the regenerating conditions
include a temperature ranging from about 100.degree. C. to about
700.degree. C. and a pressure ranging from about 0 psia to about
3000 psia.
16. The process of claim 15 wherein the regeneration concentration
of hydrogen ranges from about 10 SCF/hr/lb to about 2000 SCF/hr/lb,
based on the weight of the hydrogen sulfide sorbent.
17. The process of claim 14 wherein the hydrogen is combined with
at least one inert or light hydrocarbon diluent gas, wherein the
hydrogen is present in a volume ranging from about 50% to about
100%, based on the total volume of hydrogen and diluent, and
wherein the regenerating conditions include a temperature ranging
from about 100.degree. C. to about 700.degree. C., at a pressure
ranging from about 0 psia to about 3000 psia, for a time ranging
from about 0.25 hour to about 10 hours, and a hydrogen treat gas
rate of about 10 to about 2000 SCF/hr/lb, based on the weight of
the hydrogen sulfide sorbent.
18. The process of claim 13 wherein the regenerated sorbent has a
regenerated capacity for sulfur absorption ranging from about 5 wt.
% to about 100 wt. % of the first cycle capacity.
19. The process of claim 17 wherein the hydrogen is combined with
an inert diluent gas.
20. The process of claim 13 wherein the sorbent further comprises
at least one hydrocracking suppressor selected from Group IB, Group
IVA, and Group VIA of the Periodic Table in a suppressing quantity
sufficient to suppress hydrocracking.
21. The process of claim 20 wherein the hydrocracking suppressor is
(i) at least one of Cu, Ag, Au, Sn, and Pb, and the suppressing
quantity ranges from about 1 wt. % to about 10 wt. %, or (ii) at
least one Group VIA element, and the suppressing quantity ranges
from about 0.01 wt. % to about 2 wt. %.
22. The process of claim 13 wherein the hydrogen sulfide sorbent is
the regenerated sorbent.
23. The process of claim 22 wherein steps (a) and (b) are performed
continuously.
24. The process of claim 13 wherein at least one of the
hydrodesulfurization catalyst and the hydrogen sulfide sorbent is
supported on an inorganic refractory support.
25. The process of claim 13 wherein the weight ratio of the
hydrogen sulfide sorbent to the hydrodesulfurization catalyst
ranges from about 0.01 to about 1000.
26. The process of claim 25 wherein the hydrodesulfurization
catalyst and the hydrogen sulfide sorbent are in the form of
separate particles.
27. The process of claim 25 wherein the hydrodesulfurization
catalyst and the hydrogen sulfide sorbent are in the form of a
composited particle.
28. The process of claim 25 wherein the catalyst system is in the
form of catalyst particles, and wherein the hydrogen sulfide
sorbent is impregnated with the hydrodesulfurization catalyst.
29. The process of claim 13 wherein the hydrodesulfurization
catalyst contains at least one of Fe, Co, Ni, Mo, and W.
30. The process of claim 13 operated in at least one of a moving
bed, a bubbling bed, a non-fluidized moving bed, a fluidized bed, a
continuously stirred tank reactor, and a slurry bubble column.
31. The process of claim 30 wherein the process is a fixed bed
process operated in one of (i) cocurrent and (ii) countercurrent
mode, and wherein the catalytic hydrodesulfurization conditions
include a temperature of about 40.degree. C. to about 500.degree.
C., a pressure ranging from about 100 psig to about 3,000 psig, a
treat gas rate ranging from about 50 to about 10,000 SCF/B, and a
space velocity ranging from about 0.1 to about 100 V/V/Hr.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
Ser. No. 09/620,864, filed Jul. 21, 2000, which is a
continuation-in-part of U.S. Ser. No. 09/326,827, filed Jun. 7,
1999, now U.S. Pat. No. 6,221,240, which is a continuation-in-part
of U.S. Ser. No. 08/918,641, filed Aug. 22, 1997, issued Jul. 20,
1999 as U.S. Pat. No. 5,935,240, which claims the benefit of
Provisional Application S No. 60/024,737, filed Aug. 23, 1996.
FIELD OF THE INVENTION
[0002] This invention relates to a process for regenerating metal
oxide hydrogen sulfide sorbents using hydrogen gas. The sorbents
may be mono- or multi-metallic sorbents.
BACKGROUND OF THE INVENTION
[0003] The removal of sulfur from feedstocks is a fundamental
process of the refining and petrochemical industries. One process
for removing sulfur from a feedstock is hydrodesulfurization.
Hydrodesulfurization involves the reaction of sulfur in the
feedstock with hydrogen over supported noble metals, such as Pt,
Pd, or non-noble metal sulfides, especially Co/Mo and Ni/Mo
catalysts, at fairly severe temperatures and pressures to form
hydrogen sulfide. The performance of the hydrodesulfurization
catalysts can be inhibited by the presence of hydrogen sulfide. The
use of sorbents to remove hydrogen sulfide produced during
desulfurization improves the effectiveness of the overall
hydrodesulfurization process.
[0004] The performance of a hydrogen sulfide sorbent depends upon a
variety of properties. Thermodynamics and kinetics of sulfidation
clearly are important, for they determine the overall sulfur
capacity before breakthrough at some predetermined level of
H.sub.2S. Other important sorbent properties include stability and
regenerability in extended use, the operating conditions required
for regeneration, and the composition of the regeneration off-gas,
which largely determines the choice of a downstream sulfur recovery
process.
[0005] A practical limitation on the use of any hydrogen sulfide
sorbent is the ability to regenerate the sorbent. Zinc oxide, one
of the most promising and widely studied sorbents, has a very high
equilibrium constant for sulfidation, but it is difficult to
regenerate zinc oxide after use as a sorbent for hydrogen sulfide.
The scope and applicability of such sorbents may, therefore, be
limited by economic constraints relating to the level of sulfur
being processed, the reactor volumetrics required, and issues
pertaining to removal and disposal of the spent sorbent. These
limitations are relieved if the hydrogen sulfide sorbent is capable
of multicycle operation made possible by a means for regenerating
the sorbent.
[0006] Spinels and zeolite-based materials are regenerable hydrogen
sulfide sorbents; however, these materials are especially suited to
the removal of hydrogen sulfide from gas streams where process
temperatures are limited, preferably to about 75-125.degree. C.
These materials are inefficient for the capture of hydrogen sulfide
at the higher temperatures used in conventional
hydrodesulfurization technology.
[0007] Clinoptilolite molecular sieves also are regenerable;
however, the temperatures at which clinoptilolite molecular sieves
typically are treated also are relatively low. Clinoptilolite
molecular sieves are used to remove hydrogen sulfide from C.sub.4
to C.sub.12 feedstreams at temperatures of from about 90.degree. C.
to about 260.degree. C. Spent clinoptilolite molecular sieves are
regenerated with a purge gas at temperatures of about 150.degree.
C. to about 370.degree. C.
[0008] Regenerable solid sorbents currently used for treating hot
gaseous streams are typically based on metal oxides and are
regenerated under oxidizing conditions at temperatures frequently
greater than about 600.degree. C. The regeneration of these
sorbents using an oxidizing atmosphere requires an initial
displacement of combustible organics and hydrogen, which not only
is costly, but can be hazardous, especially at such high
temperatures.
[0009] There is still a need in the art for methods that are
capable of regenerating a variety of hydrogen sulfide sorbent
materials.
SUMMARY OF THE INVENTION
[0010] The present invention provides a process for regenerating a
hydrogen sulfide sorbent comprising providing a spent hydrogen
sulfide sorbent comprised of an effective quantity of a sorbent
metal selected from the group consisting of Fe, Ni, Co, Cu, and
polymetallics thereof on a metal oxide support, said hydrogen
sulfide sorbent having a level of sulfur defining a first cycle
capacity for absorbing hydrogen sulfide; and exposing said spent
hydrogen sulfide sorbent to a gas comprising a regenerating
concentration of hydrogen under conditions effective for said
hydrogen to regenerate said spent hydrogen sulfide sorbent, thereby
producing a regenerated sorbent.
DETAILED DESCRIPTION OF THE INVENTION
[0011] The present invention uses a reducing atmosphere, instead of
an oxidizing atmosphere to regenerate solid hydrogen sulfide
sorbents. The reducing atmosphere preferably comprises hydrogen
gas, either alone or in combination with an inert gas, preferably
nitrogen.
[0012] The regenerable sorbents of the present invention are
preferably comprised of a sorbent metal selected from Fe, Ni, Co,
and Cu on an refractory, or metal oxide support. In a preferred
embodiment, the metal is selected from the group consisting of Ni,
Co, and a combination thereof. Examples of suitable supported metal
and metal oxide based regenerable hydrogen sulfide sorbents
include, but are not necessarily limited to: 5 Co/Al.sub.2O.sub.3;
10 Co/SiO.sub.2; 20 Co/TiO.sub.2; 20 Co/ZrO.sub.2; 5
Ni/Al.sub.2O.sub.3; 10 Ni/SiO.sub.2; 20 Ni/ZrO.sub.2; 5
Cu/Al.sub.2O.sub.3; 10 Cu/SiO.sub.2; 20 Cu/ZrO.sub.2; 5
Fe/Al.sub.2O.sub.3; 10 Fe/SiO.sub.2; 20 Fe/ZrO.sub.2; 5 Co-5
Cu/Al.sub.2O.sub.3; 10 Co-10 Cu/SiO.sub.2; 10 Ni-5 Cu/SiO.sub.2; 20
Ni-2 Cu/ZrO.sub.2; 10 Co-2 Pt/Al.sub.2O.sub.3; 10 Co-5
Pd/SiO.sub.2; 10 Co-1 Sn/Al.sub.2O.sub.3; 20 Ni-4 Sn/SiO.sub.2,
wherein the numbers refer to the wt. % of metal, based on the total
weight of the sorbent.
[0013] The sorbent may be employed as a bulk metal, including but
not necessarily limited to, a finely divided skeleton metal,
including Raney metals, ponderous metals, Rieke metals, and metal
sponges.
[0014] The sorbent metal is preferably supported on an inorganic
support material in order to increase, for example, surface area,
pore volume, and/or pore diameter. Suitable support materials are
inorganic oxide support materials including, but not necessarily
limited to, alumina, silica, zirconia, carbon, silicon carbide,
kieselguhr, amorphous and crystalline silica-aluminas,
silica-magnesias, aluminophosphates, boria, titania and
combinations thereof. Preferred support materials include alumina,
zirconia, and silica. The metal(s) or metal oxide(s) may be loaded
onto these supports by conventional techniques known in the art.
Such techniques include impregnation by incipient wetness,
adsorption from excess impregnating medium, and ion exchange. In a
preferred embodiment, the regenerable sorbents are prepared by
conventional impregnation techniques using aqueous solutions of
metal halides, oxides, hydroxides, carbonates, nitrates, nitrites,
sulfates, sulfites, carboxylates and the like. The metal or metal
oxide loadings may vary with the quantity of sulfur to be adsorbed
per cycle, the cycle frequency, and the regeneration process
conditions and hardware. Metal loadings range from about 2 wt. % to
about 80 wt. %, preferably from about 3 wt. % to about 60 wt. %,
and more preferably from about 5 wt. % to about 50 wt. %, based on
the total weight of the regenerable sorbent.
[0015] After impregnation onto a support, the sorbent typically is
dried, calcined, and reduced; the latter may either be conducted ex
situ or in situ, as preferred. The regenerable sorbent may comprise
a single metal or two or more metals. Certain metal combinations
offer improved capacity, regenerability, and operability over the
use of the individual metals. For bi- and polymetallic sorbents,
similar ranges apply to each component; however, the loading may be
either balanced or unbalanced, with the loading of one metal being
greater than or less than the other. The sorbent materials of the
present invention are different than materials such as spinels,
such as those represented in U.S. Pat. No. 4,690,806 to
Schorfheide. Spinels are a group of minerals that crystallize and
are typically combinations of trivalent and bivalent oxides of
metals such as magnesium, zinc, iron, manganese, aluminum, and
chromium. In spinels, the actual substitution of metals occurs such
that the amount of aluminum is reduced by the amount of metal
cation. That is, the metal, such as Fe and Ni become part of the
crystal structure, wherein the metals of sorbent materials of the
instant invention are not part of the crystal structure of the
oxide support, but on only deposited on the surface of the oxide
support.
[0016] Regeneration of the metal sorbent, particularly Ni and Co
based sorbents, may be facilitated by including in the sorbent a
regeneration-enhancing agent that catalyzes the reduction reaction
required to restore the sorbent to its initial, active condition.
Such agents include, but are not necessarily limited to, the noble
metals of Group VIII of the Periodic Table of the Elements,
preferably a noble metal selected from the group consisting of Ir,
Pt, Pd, and Rh. The addition of from about 0.01 wt. % to about 10
wt. % of one of these metals benefits regenerability of the sorbent
by decreasing the regeneration period and/or decreasing the
regeneration temperature. Co-Ni bimetallic sorbents also experience
more complete regeneration than the corresponding Ni only
sorbent.
[0017] In addition to their activity as hydrogen sulfide sorbents,
Fe, Co, and Ni also are hydrocracking active metals. Unless their
hydrocracking activity is suppressed, these metals can cause
hydrocracking of the other hydrocarbon stream being treated,
leading to the production of low value light gas. The hydrocracking
activity of the sorbent metal can be suppressed by incorporating
from about 1 wt. % to about 10 wt. % (based on the weight of the
sorbent), preferably from about 1.5 wt. % to about 7 wt. %, and
most preferably from about 2 wt. % to about 6 wt. %, of a metal
selected from Group IB or Group IVA of the Periodic Table of the
Elements, such as Cu, Ag, Au, Sn, or Pb, preferably Cu. The
Periodic Table of the Elements referred to herein appears on the
inside cover page of the Merck Index, Twelfth Edition, Merck &
Co., 1996. Hydrogenolysis also can be suppressed by incorporating a
small amount, preferably from about 0.01 wt. % to about 1 wt. %, of
one or more of the elements selected from Group VIA of the Periodic
Table of the Elements.
[0018] Accordingly, the sorbent may be presulfided by conventional
methods such as exposing the virgin sorbent to dilute hydrogen
sulfide in hydrogen at a temperature of from about 200.degree. C.
to about 400.degree. C. for about 15 minutes to about 15 hours, or
until sulfur breakthrough is detected. Sulfur levels of the
presulfided sorbent will range from about 0.01 to about 1.0 wt. %,
preferably from about 0.02 to about 0.7 wt. %, and more preferably
from about 0.02 to about 0.5 wt. %, based on the total weight of
the sorbent. Alternately, sulfur is incorporated by exposing the
sorbent, preferably a virgin sorbent, to a dilute aqueous solution
of from about 1 to about 10% sulfuric acid under impregnation
conditions.
[0019] When desired, the regeneration-enhancing agent and the
hydrogenolysis suppressor may be incorporated into the sorbent at
the same time as the sorbent metal or later. Conventional methods
such as impregnation may be employed.
[0020] Regeneration of the sorbent by a reducing environment
generally requires more severe temperatures than those employed
during a hydrodesulfurization (HDS) reaction. Typical regeneration
temperatures range from about 100.degree. C. to about 700.degree.
C., preferably from about 250.degree. C. to about 600.degree. C.,
and most preferably from about 275.degree. C. to about 550.degree.
C. The regeneration process is operable over a range of
temperatures and pressures consistent with the intended objectives
in terms of product quality improvement and consistent with any
downstream process with which this invention is combined in either
a common or sequential reactor assembly. Operating pressures may
range from about 0 to about 3000 psia, preferably from about 50 to
about 1000 psia, at H.sub.2 gas rates of from about 10 to about
2,000 standard cubic feet per hour per pound (SCF/hr/lb) of
sorbent, preferably about 20 to about 1500 SCF/hr/lb of sorbent,
and more preferably about 100 to about 1000 SCF/hr/lb of
sorbent.
[0021] Hydrogen is preferred for the regeneration process of the
present invention and may be supplied pure or admixed with other
passive or inert gases as is frequently the case in a refining or
chemical processing environment. It is preferred that the hydrogen
stream be substantially sulfur free, which can be achieved by
conventional technologies. The regeneration stream will contain
from about 50% to about 100% hydrogen, preferably from about 70 to
about 100% hydrogen, and more preferably from about 80 to about
100% hydrogen, with any remainder being inerts or saturated light
hydrocarbon gases.
[0022] Among the properties desired in a regenerable hydrogen
sulfide sorbent are capacity to absorb hydrogen sulfide,
regenerability, and the retention of both qualities over multicycle
adsorption-regeneration sequences. Although it is preferred that
both capacity and regenerability for a given sorbent approach about
100%, it is understood that this level is not a requirement for an
effective regenerable sorbent. A capacity and regenerability that
allow a frequency of regeneration that is reasonable and compatible
with the overall process objective are acceptable and adequate.
With this qualification in mind, an "effective regenerated
capacity" is from about 5% to about 100%, by weight, of a first
cycle capacity, preferably from about 10% to about 100% of a first
cycle capacity, most preferably from about 20% to about 100% of a
first cycle capacity. A "first cycle capacity" refers to the
sorbent hydrogen sulfide capacity of a fresh or "virgin" sorbent
material.
[0023] In a preferred embodiment, the sorbent is used in
conjunction with distillate and naphtha hydrodesulfurization (HDS)
processes, preferably the processes described in U.S. Pat. Nos.
5,925,239, 5, 928,498, and 5,935,420, all incorporated herein by
reference. Typical hydrodesulfurization conditions include
temperatures from about 40.degree. C. to about 500.degree. C.
(104-930.degree. F.), preferably about 200.degree. C. to about
450.degree. C. (390-840.degree. F.), and more preferably about
225.degree. C. to about 400.degree. C. (437-750.degree. F.).
Operating pressures include about 50 to about 3000 psig, preferably
50 to about 1200 psig, and more preferably about 100 to about 800
psig at gas rates of about 50 to about 10,000 SCF/B, preferably
about 100 to about 7500 SCF/B, and more preferably about 500 to
about 5000 SCF/B. The liquid hourly space velocity may be varied
over the range of about 0.1 to about 100 V/V/Hr, preferably about
0.3 to about 40 V/V/Hr, and more preferably about 0.5 to about 30
V/V/Hr. The liquid hourly space velocity is based on the volume of
feed per volume of catalyst per hour, i.e., V/V/Hr.
[0024] Various sorbent bed configurations may be used in the
practice of the present invention. Examples of suitable bed
configurations include, but are not necessarily limited to bubbling
beds, fixed beds operated in a cocurrent or countercurrent mode,
non-fluidized moving beds, fluidized beds, or a slurry of HDS
catalyst and sorbent in a continuously stirred tank reactor
("CSTR"), or slurry bubble column. Fluidized beds may be
advantageous in conjunction with processes where continuous
regeneration of the sorbent is needed. In addition, flow-through,
fluidized bed technology which includes a disengaging zone for
catalyst and sorbent may be useful to regenerate sorbent particles.
The process can operate under liquid phase, vapor phase or mixed
phase conditions. It should be noted that the HDS catalyst and the
sorbent may be separate particles, a composite of HDS catalyst and
sorbent, and an HDS catalyst impregnated onto a sorbent. However,
when the sorbent and HDS catalyst are arranged so that the HDS
catalyst is present during sorbent reduction, undesirable
desulfiding of the HDS catalyst may result. In such cases, it would
be desirable to adjust the sorbent reduction conditions to abate
the affects of HDS catalyst desulfurization, or to subject the HDS
catalyst to a re-sulfiding step prior to re-use, or to employ an
HDS catalyst that does not require sulfiding, such as a noble metal
HDS catalyst. The HDS catalyst may be re-sulfided by contacting the
catalyst with the sulfur-containing hydrocarbon feed.
[0025] Fixed bed configurations may be operated in either of
cocurrent and countercurrent modes, i.e., with hydrogen-containing
treat gas flowing over the HDS catalyst in the same or opposite
direction as the sulfur-containing feed. In another embodiment, the
hydrogen-containing treat gas is employed in a "once-through"
arrangement is, therefore, not recycled. Countercurrent HDS
arrangements may be preferred in cases where increased contacting
between the sulfur-containing feed, treat gas, and catalyst would
be desired and in cases where increased H.sub.2S stripping would be
beneficial. Fluidized beds may be advantageous in conjunction with
processes where continuous regeneration of the sorbent is needed.
In addition, flow-through, fluidized bed technology which includes
a disengaging zone for catalyst and sorbent may be useful to
regenerate sorbent particles.
[0026] Those skilled in the art are aware that the choice of bed
configuration for an HDS catalyst and a sorbent depends upon the
objective of the overall process, particularly when the process is
integrated with one or more subsequent processes, or when the
objective of the overall process is to favor the selectivity of one
aspect of product quality relative to another. However, it is
preferred that the sorbent not be placed upstream of the HDS
catalyst.
[0027] A preferred embodiment uses a stacked bed configuration with
a swing reactor designed to permit regeneration of spent sorbent
while a fresh sorbent is placed in service. In a stacked bed
configuration, the HDS catalyst is stacked, or layered, above and
upstream of the sorbent. The stacked beds may either occupy a
common reactor, or the HDS catalyst may occupy a separate reactor
upstream of the reactor containing the sorbent. This dedicated
reactor sequence is preferred when the HDS catalyst and the sorbent
require different reactor temperatures.
[0028] In another embodiment, the sorbent and the HDS catalyst are
used in a mixed bed configuration. In this configuration, particles
of the HDS catalyst are intimately intermixed with those of the
sorbent. In both the stacked bed and the mixed bed configurations,
the HDS catalyst particles and the sorbent particles may be of
similar or identical shapes and sizes. The particles of one
component may also differ, for example, in shape, density, and/or
size from the particles of the second component. The use of
particles having different sizes may be employed when, for example,
is simple physical separation of the bed components upon discharge
or reworking.
[0029] In yet another embodiment, the two components are blended
together to form a composite particle incorporating both the HDS
catalyst and the sorbent or individual discrete components. For
example, a finely divided, powdered Pt on alumina HDS catalyst is
uniformly blended with a regenerable sorbent and the mixture is
formed into a common catalyst particle. Or, the regenerable sorbent
may be incorporated into the support, and Pt, for example, may be
impregnated onto the sorbent containing support, such as
alumina.
[0030] In another two component configuration, an alumina support
is impregnated with an HDS metal or metals and a sorbent on a
common base. Both metals may be distributed uniformly throughout
the catalyst particle, or the sorbent and/or HDS components may be
deposited preferentially on the outside of the particle to produce
a rim, or eggshell, sorbent or HDS rich zone.
[0031] A three component bed configuration also may be used. In one
embodiment, denoted as mixed/stacked, a mixed HDS catalyst/sorbent
bed is configured upstream of a single HDS/hydrogenation catalyst.
In another embodiment, known as a stacked/stacked/stacked
configuration, the three components are layered from top to bottom
as follows: HDS catalyst/sorbent/HDS catalyst. In one embodiment,
three component systems may occupy a common reactor. In another
embodiment, a three component system may be used in a two-reactor
train in which the HDS catalyst/sorbent occupy a lead reactor in a
mixed or stacked configuration and a HDS catalyst occupies the tail
reactor. This arrangement allows for the operation of two reactor
sections at different process conditions, especially temperature,
and imparts flexibility in controlling process parameters such as
selectivity and/or product quality.
[0032] The composition of the bed is independent of configuration
and may be varied in accordance with the specific or integrated
process to which the invention is applied. If the capacity of the
sorbent is limiting, the composition of the bed must be consistent
with the expected lifetime, or cycle, of the process. These
parameters are in turn sensitive to the sulfur content of the feed
being processed and to the degree of desulfurization desired. For
these reasons, the composition of the bed is flexible and variable,
and the optimal bed composition for one application may not serve
an alternative application equally well. In general, the weight
ratio of the sorbent to the hydrodesulfurization catalyst may range
from about 0.01 to about 1000, preferably from about 0.5 to about
40, and more preferably from about 0.7 to about 30. For three
component configurations, these ranges apply to the mixed zone of
the mixed/stacked arrangement and to the first two zones of the
stacked/stacked/stacked design. The hydrodesulfurization catalyst
present in the final zone of these two arrays is generally present
at a weight ratio that is equal to or less than the combined weight
compositions of the upstream zones.
[0033] The process may be used as a stand-alone process for, for
example, fuels, lubes, and chemicals applications. Alternately, the
process may be combined and integrated with other processes in a
manner so that the net process affords product and process
advantages and improvements relative to the individual processes
not combined. The following embodiments are included to illustrate,
but not limit, uses for the processes of this invention.
[0034] Processes relating to fuels processes include:
desulfurization of gasoline range feed and product streams;
desulfurization of distillate streams; desulfurization of FCC
streams preceding recycle to 2.sup.nd stage process;
desulfurization of hydrocracking feeds; multi-ring aromatic
conversion through selective ring opening; aromatics saturation
processes; hydroisomerization; sulfur removal from natural,
synthesis, and recycle gas streams and from field condensate
streams. Processes relating to the manufacture of lubricants
include: hydrocracking, product quality improvement through mild
finishing treatment; optimization of white oil processes by
decreasing catalyst investment and/or extending service factor.
Processes relating to chemical processing include: substitute for
environmentally unfriendly nickel based hydroprocesses; preparation
of high quality feedstocks for olefin manufacture through various
cracking processes and for the production of oxygenates by
oxyfunctionalization processes; production of solvent and polymer
grade olefins and aromatics.
[0035] This invention is illustrated by, but not limited to the
following examples, in which the following experimental conditions
were used unless otherwise indicated:
GENERAL CONDITIONS
[0036] The capacity and hydrogen regenerability of the hydrogen
sulfide sorbents were assessed using a Cahn TG 121
Thermogravimetric Analyzer using nominally equivalent weight
charges of each sorbent. The candidate sorbents were initially
calcined in air at 400.degree. C. for 3 hr prior to being placed in
the analyzer. The sorbent was heated at 500.degree. C. for 1 hr in
hydrogen and then cooled to 325.degree. C. and exposed to a gas
blend containing 1000 vppm H.sub.2S in H.sub.2 for a period of 2 hr
during which interval the weight gain associated with the
adsorption of H.sub.2S was recorded. The spent sorbent subsequently
was heated to 500.degree. C. in H.sub.2 for one hour and to
550.degree. C. for one hour during which interval the desorption of
H.sub.2S, or the regeneration of the sorbent, was noted. In
multicycle testing this sequence was duplicated as noted to
simulate repetitive adsorption-regeneration cycles. Regenerability
was further confirmed by the observation of phase changes using a
controlled environment, high temperature cell mounted on a X-ray
diffractometer.
[0037] The sorbents were prepared by incipient wetness impregnation
of the various support materials with aqueous solutions of the
metal nitrates. The extrudates were air dried under vacuum at
120.degree. C. for 24 hr. Calcination in flowing air was carried
out in a small catalyst pretreat unit or in a thermogravimetric
unit dedicated to this function. In both cases the calcination was
conducted at 400.degree. C. for 3 hr. All sorbent compositions in
the examples are nominal wt. % metal on support.
EXAMPLE I
[0038] This experiment compared zinc oxide (a non-hydrogen
regenerable sorbent) as a control to supported Fe, Co, Ni, and Cu
sorbents.
1 Sample No. Sorbent Sulfur Gain, Wt. % Regeneration, % 1 ZnO 8.0 0
2 10 Fe/ZrO.sub.2 5.3 45 3 10 Co/ZrO.sub.2 4.9 95 4 10 Ni/ZrO.sub.2
3.5 73 5 20 Ni/ZrO.sub.2 6.1 79 6 20 Cu/ZrO.sub.2 4.3 63 7 17
Co/TiO.sub.2 8.9 28
[0039] % Regeneration refers to the percent of chemisorbed sulfur
removed from the sorbent during regeneration. If no sulfur is
released during regeneration, this value is zero. Total removal of
sulfur during regeneration corresponds to 100% regeneration.
[0040] The results demonstrate that Fe, Co, Ni, and Cu were active
hydrogen sulfide sorbents and were capable of being regenerated by
hydrogen to varying degrees. Co and Ni were more regenerable than
Fe and Cu on a common support. Metal loading (Samples 4 and 5)
exerted an influence on capacity but not on regenerability. Titania
(Sample 7) was least preferred as a support although the degree of
regenerability was within the limits of this invention.
EXAMPLE II
[0041] Experiments were done to determine what factors had an
impact on capacity and regenerability.
2 Sample No. Sorbent Sulfur Gain, Wt. % Regeneration, % 8 20
Co/SiO.sub.2 7.8 98 9 20 Co/Al.sub.2O.sub.3 7.6 99 10 20
Co/ZrO.sub.2 8.0 73 11 10 Co/ZrO.sub.2 4.9 95 12 10 Co/SiO.sub.2
4.1 100 13 10 Co/Al.sub.2O.sub.3 4.1 100
[0042] Samples 8-13 illustrate that, for a common metal, capacity
and percent regeneration were independent of support for the
supports shown. As expected, capacity was a function of metal
loading, but degree of regeneration was not influenced by total
metal content. Samples 14-15 and 16-18 illustrate that for Co on a
common support, the hydrogen sulfide capacity of the sorbent was a
function of metal content, but that the kinetics of hydrogen
regeneration were insensitive to metal loading.
3 Regeneration Rate, Sample No. Sorbent Sulfur Gain, Wt. % mg/hr 14
10 Co/ZrO.sub.2 4.9 0.4 15 20 Co/ZrO.sub.2 8.0 0.4 16 5
Co/Al.sub.2O.sub.3 2.3 0.5 17 10 Co/Al.sub.2O.sub.3 4.1 0.6 18 20
Co/Al.sub.2O.sub.3 7.6 0.6 Regeneration Rate = mg of sulfur removed
per hour during hydrogen regeneration.
EXAMPLE III
[0043] The hydrogen sulfide sorbent of Sample 5 (Example I) was
subjected to multicycle adsorption-regeneration by the procedure
described above. The 20 Ni/ZrO.sub.2 sorbent was subject to five
complete cycles without significant loss of hydrogen sulfide
capacity and hydrogen regenerability. The sulfur weight gain and
degree of regenerability were near parity with the values of Sample
5.
EXAMPLE IV
[0044] The hydrogen sulfide sorbent of Sample 17 (Example II) was
subjected to multicycle adsorption-regeneration by the procedure
described above. The 10 Co/Al.sub.2O.sub.3 sorbent was subject to
six complete cycles without significant loss of hydrogen sulfide
capacity and hydrogen regenerability. The sulfur weight gain and
degree of regenerability were at parity with the values of Sample
17.
EXAMPLE V
[0045] A 1.0 g sample of the 10 Co/Al.sub.2O.sub.3 sorbent of
Sample 17 (Example II) was diluted with 30 g of inerts and charged
to a flow-through, fixed bed reactor. The sorbent was reduced in
hydrogen at 500.degree. C. for 1 hr and was then subjected to a
blend of 1000 vppm H.sub.2S in H.sub.2 at 300.degree. C. and a gas
flowrate of 50 ml/min. The hydrogen stream exiting the sorbent bed
was monitored for H.sub.2S content using a H.sub.2S detector, which
measured the breakthrough time approximating complete saturation of
the sorbent. The sorbent was evaluated in this manner in three
distinct tests, which are summarized below.
4 Test Sorbent Breakthrough Time, hr Sorbent S Content, Wt. % 1 9.8
3.1 2 9.7 2.9 3 9.2 2.6
[0046] The calculated sulfur value for the conversion of the
sorbent Co content to Co.sub.9S.sub.8 was 3.0 wt. %. The data in
the preceding table confirm the TGA results in a fixed bed
configuration and indicate reproducible and efficient utilization
of the sorbent capacity.
EXAMPLE VI
[0047] The procedure of Example V was followed except that the
sorbent consisted of three independent zones separated by inerts,
each zone containing the 10 Co/Al.sub.2O.sub.3 sorbent diluted with
inerts. Hydrogen sulfide breakthrough occurred with this bed at
29.3 hr., a period about three times that seen for a single sorbent
zone. Each zone was separated and analyzed for sulfur; the sulfur
values for the top, middle, and bottom zones were 3.1, 3.3, and 3.3
wt. %, respectively. These values reflect highly efficient
operation of the sorbent.
EXAMPLE VII
[0048] The procedure of Example VI was repeated using the three
zone sorbent bed as described. After H.sub.2S breakthrough was
detected at 27 hr, the sorbent bed was regenerated with hydrogen at
500 ml/min at 450.degree. C. for 3 hr, 500.degree. C. for 3 hr, and
finally at 550.degree. C. for 10 hr. The three sorbent zones were
separated and analyzed for sulfur; the sulfur values for the top,
middle, and bottom zones were 0.2, 0.2, and 0.2 wt. %,
respectively. These sulfur values demonstrate hydrogen regeneration
of the total sorbent bed at a level of about 95% regeneration
efficiency.
EXAMPLE VIII
[0049] The procedure of Example VIII was repeated using a single
sorbent zone. After H.sub.2S breakthrough was detected, the bed was
regenerated with hydrogen. The sorbent was then cooled to
300.degree. C. and exposed to the dilute H.sub.2S in H.sub.2
stream. The adsorption-regeneration cycle was repeated for four
cycles at the conclusion of which the sorbent was sulfided a final
time. The results are summarized in the following table.
5 Cycle # Breakthrough Time, hr Sorbent S Content, Wt % 1 10.5 n/a
2 13.6 n/a 3 14.3 n/a 4 14.2 3.1
[0050] The breakthrough value times indicate successful and
efficient regeneration of the sorbent following each exposure to
H.sub.2S. If essentially complete regeneration per cycle were not
occurring, a significant decrease in breakthrough time for each
succeeding cycle would be expected. The sulfur content of the
sorbent illustrated that the sulfur capacity was unimpaired after
multicycle service.
EXAMPLE IX
[0051] The 10 Co/Al.sub.2O.sub.3 sorbent of Sample 17 (Example II)
was subjected to dilute H.sub.2S in H.sub.2 as described
previously. After H.sub.2S breakthrough was detected, the sorbent
was regenerated using variations in the H.sub.2 treat rate,
temperature and time as shown in the following table. The results
indicate that the regeneration period is a function of these
process variables and that these may be selected to maintain the
degree of regeneration and/or the regeneration period required to
reach a specified regeneration efficiency.
6 H.sub.2 Regen Breakthr. Flowrate, 1.sup.st, .degree. C.-
3.sup.rd, .degree. C.- Sorbent S, # Time, hr ml/min hr 2.sup.nd,
.degree. C.-hr hr Wt. % 1 12.5 900 450-3 500-3 550-10 0.2 2 13.0
300 450-3 500-3 550-10 0.2 3 14.1 300 450-3 500-3 550-3 0.2 4 13.8
300 450-1 500-1 550-1 1.5 5 14.5 500 450-1 500-1 550-1 0.3
EXAMPLE X
[0052] Experiments were performed to determine whether a
combination of metals in the sorbent had an impact on the
regeneration achieved. The results are given in the following
table:
7 Sulfur Gain, Sample No. Sorbent Wt. % Regeneration, % Reference
10 Co/Al.sub.2O.sub.3 4.1 100 Reference 10 Ni/ZrO.sub.2 3.5 73 19 5
Co-15 Ni/SiO.sub.2 7.3 90 20 10 Co-10 Ni/SiO.sub.2 7.4 100 21 15
Co-5 Ni/SiO.sub.2 7.9 100 22 20 Co-1.5 Re/Al.sub.2O.sub.3 7.4 100
23 20 Co-5 Re/SiO.sub.2 6.6 100 24 20 Co-5 Re-2 Pt/SiO.sub.2 5.3
100 25 10 Co-2 Ru/SiO.sub.2 4.1 100 26 10 Co-2 Pd/SiO.sub.2 4.3 100
27 10 Co-2 Pt/SiO.sub.2 3.0 100
[0053] Samples 19-21 show that a set of Co-Ni based sorbents, where
the total metal loadings is equivalent but the ratio of Co to Ni is
varied, shared a common sulfur capacity and regeneration
efficiency. The sulfur capacities agreed with those predicted by
the monometallic sorbents, but the Co-Ni bimetallic sorbents
unexpectedly experienced more complete regeneration than the
corresponding Ni only sorbent.
[0054] Samples 22-24 illustrate that the Co-Re sorbents had
reasonable sulfur capacity, which declined with increasing Re
loading due to a decrease in the rate of reaction with H.sub.2S
(not shown) which limited sulfur uptake within a fixed period of
time. The Co-Re sorbents were readily regenerable with hydrogen as
the data indicate.
[0055] Samples 25-27 demonstrate that the incorporation of Group
VIII noble metals did not impair the sulfur capacity of Co although
the rate of sulfur uptake was retarded in the presence of Pt.
Hydrogen regeneration of these bimetallic sorbents occurred readily
with essentially quantitative recovery of fresh sorbent
capacity.
EXAMPLE XI
[0056] A 1.0 g sample of various bimetallic sorbents was diluted
with 30 g of inerts and charged to a flow-through, fixed bed
reactor. The sorbent was reduced by hydrogen at 500.degree. C. for
1 hr and then was subjected to a blend of 1000 vppm H.sub.2S in
H.sub.2 at 300.degree. C. and a gas flowrate of 50 ml/min. The
hydrogen stream exiting the sorbent bed was monitored for H.sub.2S
content using a H.sub.2S detector, which measured the breakthrough
time approximating complete saturation of the sorbent.
[0057] After the initial breakthrough of H.sub.2S was detected, the
sorbent bed was regenerated in H.sub.2 flowing at 300 ml/min using
temperature-time programs of 450.degree. C. for 3 hr, 500.degree.
C. for 3 hr, and finally 550.degree. C. for 3 hr. This
absorption-regeneration sequence was repeated to simulate two or
three complete cycles. The residual sulfur content of the sorbent
following the second regeneration was measured analytically. The
results are given in the following table:
8 Breakthrough Time, Sample Sorbent hr, #-Cycles Sorbent S wt. %
Reference 10 Ni/ZrO.sub.2 16.8 - 2 0.8 28 20 Ni-2Cu/ZrO.sub.2 28.4
- 2 2.0 29 10 Co-1 Pt/SiO.sub.2 13.8 - 2 0.1 30 10 Co-5
Cu/SiO.sub.2 14.4 - 2 1.2 31 10 Co-5 Cu/SiO.sub.2 11.5 - 3 0.7
[0058] The breakthrough times for the second or third cycle
sorbents are characteristic of the breakthrough period of fresh
sorbent and indicate successful hydrogen regeneration of these
bimetallic sorbents. If hydrogen regeneration were not occurring,
the breakthrough period for the multicycle sorbents would be
significantly decreased. The sulfur contents of the regenerated
sorbents demonstrate that a degree of regeneration >60% was
achieved in all cases except for Ni-Cu/ZrO.sub.2 where the rate of
regeneration was slow relative to the remaining sorbents.
EXAMPLE XII
[0059] The Co/Al.sub.2O.sub.3 sorbent of Sample 13 (Example II) was
subjected to a heptane cracking test to measure the hydrogenolysis
activity of the sorbent as reflected in hydrocracking to methane.
The same Co/Al.sub.2O.sub.3 sorbent was impregnated with dilute
sulfuric acid to introduce 0.05 wt. % sulfur into the sorbent.
[0060] A sulfuric acid stock solution was prepared by diluting 1
mL. of concentrated sulfuric acid with 50 mL of deionized water. A
solution of 0.5 mL sulfuric acid stock solution in 9.0 mL of
deionized water was added dropwise with stirring to 10 g of a
previously prepared 10% Co/Al.sub.2O.sub.3 sorbent. The sorbent was
allowed to stand overnight and was charged to a reactor for
calcination in air at 400.degree. C. for 3 hours. The material was
converted to 14-35 mesh. Anal: Co 9.91; S. 0.055 (wt. %).
[0061] The sulfided sorbent was subjected to a heptane cracking
test to measure the hydrogenolysis activity of the sorbent as
reflected in hydrocracking to methane. The same Co/Al.sub.2O.sub.3
sorbent also was impregnated with dilute sulfuric acid to introduce
0.25 wt. % sulfur into the sorbent. The sulfided sorbent was
subjected to a heptane cracking test to measure the hydrogenolysis
activity of the sorbent as reflected in hydrocracking to methane.
The results appear in the table below.
9 Hydrogenolysis Activity Of Unsulfided And Sulfided Co Sorbents
n-Heptane, 500 psig, 5 W/H/W, H.sub.2/Oil = 6 Sample 32 33 34
Sorbent 10 Co/Al.sub.2O.sub.3 10 Co-0.05 S/Al.sub.2O.sub.3 10
Co-0.25 S/Al.sub.2O.sub.3 Reaction 300 325 300 325 300 325 Temp.
.degree. C. Methane, 10.4 47.5 1.1 2.5 0.0 0.0 wt. %
[0062] Examples II, IV, and V illustrate that supported Co sorbents
are highly active for the capture of hydrogen sulfide, have high
hydrogen sulfide capacity, and are capable of retained capacity
following multicycle hydrogen regeneration. Sample 32 reveals that
this sorbent is very active for hydrocracking feedstocks to light
gas. Samples 33 and 34 demonstrate that this hydrocracking activity
is greatly decreased and eliminated by the presence of low levels
of sulfur.
EXAMPLE XIII
[0063] The procedure of Example II was repeated using the sulfur
bearing Co/Al.sub.2O.sub.3 sorbents of Examples 33 and 34. The
capacity of the sorbent for the capture of hydrogen sulfide was
equal to that of Sample 13 in Example II indicating that the
affinity of the sorbent for the capture of hydrogen sulfide was not
impaired by the presence of low levels of sulfur.
EXAMPLE XIV
[0064] A 10 Co-10 Cu/SiO.sub.2 sorbent was synthesized. A solution
of 12.3 g of Co(NO.sub.3).sub.2(6 H.sub.2O) and 9.6 g of
Cu(NO.sub.3).sub.2(3 H.sub.2O) in 50 mL of deionized water was
added dropwise with stirring to 25 g of SiO.sub.2 extrudates
contained in a small evaporating dish. The mixture was permitted to
stand at room temperature until dry and was then dried under vacuum
at 120.degree. C. for 24 hr. The sorbent was charged to a small
catalyst pretreat unit and calcined in air at 400.degree. C. for 3
hour. The sorbent was converted to 14-35 mesh particles for
testing. Anal: Co, 8.23 wt. %; Cu, 8.12 wt. %. Multicycle capacity
and regenerability in service was demonstrated by TGA.
EXAMPLE XV
[0065] The following sorbents were subjected to a heptane cracking
test to measure the hydrogenolysis activity of the sorbent as
reflected in hydrocracking to methane: the Co/Al.sub.2O.sub.3
sorbent of Sample 13 (Example II); the Ni/ZrO.sub.2 sorbent of
Sample 5 (Example I); the Co/ZrO.sub.2 sorbent of Sample 11
(Example II); and, the Ni-Cu/ZrO.sub.2 sorbent of Sample 28
(Example XI); the Co-Cu/ZrO.sub.2 sorbent of Sample 30 (Example
XI); and a 10 Co-10 Cu/SiO.sub.2 sorbent (Sample 35). The results
appear in the following table:
10 Hydrogenolysis Activity Of Unsulfided And Sulfided Co Sorbents
n-Heptane, 500 psig, 5 W/H/W, H.sub.2/Oil = 6 Sample 13 5 11 28 30
35 Sorbent 10 Co/ 20 Ni/ 10 Co/ 20 Ni-2 Cu/ 10 Co-5 Cu/ 10 Co- 10
Cu/ Al.sub.2O.sub.3 ZrO.sub.2 ZrO.sub.2 ZrO.sub.2 ZrO.sub.2
SiO.sub.2 Methane, 47.5 75.0 85.0 5.0 0.0 0.0 Wt. %
[0066] Based on the foregoing, it was concluded that the
hydrocracking activity of the monometallic sorbents is extremely
high. This hydrogenolysis activity is effectively suppressed by the
addition of a hydrogenolysis moderator. Neither the sulfur capacity
nor the ability to be regenerated by treatment with hydrogen are
compromised in these bimetallic catalysts relative to their
monometallic analogs (Samples 28, 30).
EXAMPLE XVI
[0067] Experiments were performed to determine whether hydrogen
regeneration could be augmented by adding, for example, a noble
metal to the sorbent. The results appear in the following
table:
11 Sulfur Gain, % Rengenerated at Sample Sorbent Wt. % 500.degree.
C. for 1 hr 12 10 Co/SiO.sub.2 4.3 47 36 10 Co-0.5 Pd/SiO.sub.2 4.3
55 37 10 Co-1.0 Pd/SiO.sub.2 4.4 59 26 10 Co-2.0 Pd/SiO.sub.2 4.4
64 38 10 Co-5.0 Pd/SiO.sub.2 4.4 65 39 10 Co-0.5 Pt/SiO.sub.2 4.2
60 40 10 Co-1.0 Pt/SiO.sub.2 3.9 70 27 10 Co-2.0 Pt/SiO.sub.2 3.0
88 41 10 Co-1.0 Pt-1.0 Pd/SiO.sub.2 3.9 74
[0068] Sample 12 exhibits the sulfur capacity typical of a
supported 10% Co hydrogen sulfide sorbent. At conditions purposely
selected to prevent complete regeneration by hydrogen treatment
(500.degree. C. for 1 hr), the cobalt sorbent lost 47% of the
adsorbed hydrogen sulfide, or is 47% regenerated. The addition of
Pd (Samples 26, 36-38) had no influence on the sulfur capacity, but
the presence of Pd clearly facilitated hydrogen regeneration at
common conditions. The degree of regeneration increased with
increasing Pd up to a level of about 2 wt. % Pd.
[0069] Samples 27, 39, 40 illustrate a similar trend with the
presence of Pt, which is more effective than Pd at promoting the
rate of hydrogen regeneration. The apparent loss of sulfur capacity
at .about.2 wt. % Pt is largely due to a decrease in the kinetics
of sulfur pickup.
[0070] Sample 41, where Pt and Pd are present at equivalent wt. %
loadings, but at differing atomic loadings, displays a synergism
between the two noble metals yielding a more facile regeneration
than either metal alone when present at 1 wt. %.
[0071] The data collectively illustrate that the hydrogen
regeneration of a highly saturated hydrogen sulfide sorbent is
promoted by the presence of one or more noble metals from Group
VIII of the Periodic Table of the Elements. This promotional effect
may be used either to shorten the regeneration period, to decrease
the regeneration temperature, or both.
* * * * *