U.S. patent number 3,894,932 [Application Number 05/417,001] was granted by the patent office on 1975-07-15 for conversion of hydrocarbons with "y" faujasite-type catalysts.
This patent grant is currently assigned to Mobil Oil Corporation. Invention is credited to Hartley Owen.
United States Patent |
3,894,932 |
Owen |
July 15, 1975 |
Conversion of hydrocarbons with "y" faujasite-type catalysts
Abstract
A single riser fluid catalytic cracking operation for converting
a gas oil feed material and a gaseous fraction rich in C.sub.3
-C.sub.4 hydrocarbons to form aromatics and isobutane is described.
Conversion of the C.sub.3 -C.sub.4 rich fraction is accomplished at
a high temperature in an initial annular portion of the riser
reactor before charging a gas oil feed to the suspension formed in
the annular section. C.sub.3 -C.sub.4 rich hydrocarbon streams may
be converted at a lower temperature in a downstream portion of the
riser.
Inventors: |
Owen; Hartley (Belle Mead,
NJ) |
Assignee: |
Mobil Oil Corporation (New
York, NY)
|
Family
ID: |
23652193 |
Appl.
No.: |
05/417,001 |
Filed: |
November 19, 1973 |
Current U.S.
Class: |
208/74; 208/78;
208/155; 208/156; 208/164; 585/271; 585/312; 585/319; 585/407;
208/120.15 |
Current CPC
Class: |
C10G
11/18 (20130101) |
Current International
Class: |
C10G
11/18 (20060101); C10G 11/00 (20060101); C10g
037/02 (); C10g 011/18 (); B01j 009/20 () |
Field of
Search: |
;208/74,62,71,78 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gantz; Delbert E.
Assistant Examiner: Schmitkons; G. E.
Attorney, Agent or Firm: Huggett; Charles A. Farnsworth;
Carl D.
Claims
I claim:
1. A method for converting hydrocarbons with faujasite conversion
catalyst which comprises,
passing an upflowing suspension of hot regenerated faujasite
conversion catalyst in a C.sub.3 -C.sub.4 gaseous hydrocarbon
fraction at a temperature of about 1250.degree.F. through a lower
annular portion of a riser conversion zone for a residence time in
the range of 0.1 to 2 seconds,
introducing a higher boiling hydrocarbon fraction of at least gas
oil boiling range into said upflowing suspension downstream of said
annular zone at one or more spaced apart downstream intervals and
converting the introduced higher boiling fraction at a temperature
in the range of 900.degree.F. to 1000.degree.F. at a hydrocarbon
residence time up to about 10 seconds to a product rich in
aromatics,
separating the suspension following traverse of said riser
conversion zone into a hydrocarbon phase and a catalyst phase, and
sequentially stripping and regenerating said separated catalyst
phase.
2. The method of claim 1 wherein the suspension after traversing
the riser conversion zone is cyclonically separated into a
hydrocarbon phase and a catalyst phase, the catalyst phase is
stripped with stripping gas and a portion of the stripped catalyst
is recycled to the inlet of the riser conversion zone.
3. A method for converting gas oils and low boiling C.sub.3
-C.sub.4 hydrocarbons with a faujasite conversion catalyst which
comprises,
passing a suspension of faujasite cracking catalyst suspended in a
hydrocarbon feed material of at least gas oil boiling range at an
initial temperature of at least 1000.degree.F. upwardly through a
riser conversion zone under conditions to provide a hydrocarbon
residence time up to about 10 seconds, introducing hydrocarbons
rich in C.sub.3 and C.sub.4 hydrocarbons into said suspension to
obtain conversion thereof to aromatics and isobutane,
separating the suspension into a hydrocarbon phase and a catalyst
phase, recovering the hydrocarbon phase, and stripping the
separated catalyst before regeneration thereof.
4. In a riser hydrocarbon conversion operation the improvement
which comprises,
passing a suspension comprising a gas oil high boiling hydrocarbon
fraction admixed with faujasite catalyst at a temperature of at
least 950.degree.F. upwardly through a conversion zone,
adding the high boiling fraction incrementally to the upflowing
suspension,
introducing a hydrocarbon fraction rich in C.sub.3 and C.sub.4
hydrocarbons into a downstream portion of said suspension in said
riser conversion zone maintained under conditions to produce a
product rich in isobutane,
separating the suspension upon discharge from the conversion zone
into a hydrocarbon phase and a catalyst phase, recovering the
hydrocarbon phase, recovering and stripping the catalyst phase.
Description
BACKGROUND OF THE INVENTION
The field of catalytic cracking and particularly the operations
related to dense and dilute fluid phase catalytic operations have
been undergoing progressive development since early 1940. As new
experience was gained in operating and design parameters, new
catalyst compositions were developed which prompted a further
refinement in known operating technology. With the development of
high activity crystalline zeolite catalyst, the industry found a
further need to improve upon its operating parameters to take
advantage of the new catalysts activity, selectivity and operating
sensitivity. The present invention is thus concerned with an
improved method of cracking or catalytic operation which relates
the catalyst activity and selectivity to processing parameters in a
manner mutually contributing to improving the conversion of
available refinery feed materials.
SUMMARY OF THE INVENTION
The present invention is directed to the conversion of hydrocarbons
in the presence of a relatively large pore crystalline material of
the faujasite type of crystalline zeolite. In a more particular
aspect, the present invention is concerned with more completely
utilizing the activity and selectivity characteristics of "X" and
"Y" faujasite crystalline aluminosilicate conversion catalyst to
upgrade gas oil feed materials and normally gaseous hydrocarbon
products such as those obtained in a gas oil conversion operation.
In yet another aspect the present invention is concerned with using
a faujasite cracking catalyst separated from a gas oil hydrocarbon
conversion zone to upgrade particularly C.sub.3 and C.sub.4 rich
hydrocarbon gaseous material to higher boiling gasoline boiling
material. The C.sub.3 -C.sub.4 rich gaseous material may be the
product of a high temperature gas oil cracking operation or the
gaseous hydrocarbons may be recovered from other available refinery
sources. More particularly, the present invention is concerned with
the cracking of gas oil boiling range hydrocarbon feed materials
with a Y faujasite cracking catalyst under elevated temperature
cracking conditions selected from within the range of 900.degree.F.
to about 1100.degree.F. at a hydrocarbon residence time in a once
through conversion zone restricted to within the range 1 1 to about
12 seconds. Catalyst to oil ratios may be selected from within the
range of 4 to about 20. Generally, it is preferred to accomplish
cracking of the gas oil in an upflowing riser conversion zone
discharging into cyclonic separation means in an upper portion of
an enlarged vessel wherein products of gas oil cracking are
separated from the catalyst used. The riser suspension may also be
discharged adjacent the inlet to cyclonic separating means rather
than directly into the cyclonic separating means as shown. The
separated catalyst is collected in the lower portion of the vessel
which is in open communication with the upper end of a lower
extending stripping zone wherein the catalyst is stripped with
countercurrent upwardly flowing stripping gas such as steam. The
stripped products and products of conversion separated from the
catalyst discharge from the riser conversion zone are combined with
the cyclonically separated hydrocarbon vapors and passed to one or
more downstream separation zones.
In accordance with this invention, C.sub.3 -C.sub.4 rich
hydrocarbon mixture or an isobutylene rich stream is contacted with
the Y faujasite conversion catalyst before contact with gas oil
boiling range feed material in an initial portion of the riser or
after initial contact with gas oil feed. The gas oil conversion is
accomplished at a catalyst to hydrocarbon feed ratio in the range
of 4 to about 10 and an elevated hydrocarbon feed temperature
sufficient to form a suspension at a temperature in the range of
about 950.degree. to about 1100.degree.F. Conversion of the C.sub.3
-C.sub.4 rich hydrocarbon feed, on the other hand, is accomplished
at temperatures above that relied upon for gas oil cracking or
under lower temperature gas oil conversion temperatures. Thus the
C.sub.3 -C.sub.4 hydrocarbon rich feed which may be charged to the
riser to encounter the regenerated catalyst at its highest
temperature received from the regeneration zone may be converted at
a temperature of about 1250.degree.F. before the suspension thereof
is brought in contact with gas oil feed in the riser. Therefore,
the residence time of the C.sub.3 -C.sub.4 hydrocarbon rich feed at
high temperature conditions before gas oil contact may be up to 1
or 2 seconds or it may be only a fraction of a second, as little as
one-tenth of a second, but the contact time under lower temperature
conditions may be equal to or greater than that employed for the
gas oil conversion operation. In any event, the conversion zone is
maintained under conditions which can provide a hydrocarbon
residence time within the range of 1 to about 12 seconds before
separation of the suspension. This is so since either one of the
feeds may be introduced to the riser conversion zone at spaced
apart intervals lying in a downstream portion thereof. During this
combination conversion operation, the Y faujasite catalyst provides
hydrogen transfer activity and cyclization selectivity which
converts introduced and formed C.sub.3 -C.sub.4 hydrocarbons to
aromatics; alkyl aromatics and some low boiling gaseous
material.
The C.sub.3 -C.sub.4 rich hydrocarbon feed material or the
isobutylene rich feed may be separately furnace heated or heated by
other suitable means to a temperature suitable for introducing to
the riser conversion zone. The C.sub.3 -C.sub.4 rich hydrocarbon
feed initially contacting the freshly regenerated catalyst may
encounter significantly different high temperature residence times
depending upon whether the gas oil is introduced to an initial,
intermediate or downstream portion of the riser conversion
zone.
Catalyst particles separated from the conversion zone are stripped
in a stripping zone countercurrent to rising stripping gas such as
steam as mentioned above. The stripped catalyst is then transferred
to a catalyst regeneration zone, not shown, for the removal of
deposited carbonaceous material by burning, thereby heating the
catalyst to an elevated temperature in the range of 1150.degree.F.
up to 1,500.degree. or 1,600.degree.F.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a diagrammatic sketch in elevation of an arrangement
of hydrocarbon conversion zones for catalytically converting
selected hydrocarbon feeds with a fluid conversion catalyst.
DISCUSSION OF SPECIFIC EMBODIMENTS
Referring now to the FIGURE, there is shown a riser conversion zone
2 supplied with hot regenerated catalyst by conduit 4 provided with
a catalyst flow control valve 6. Steam is introduced to a bottom
portion of riser 2 by one or more steam inlet conduits 8 and/or 10
and a gas oil feed is introduced by inlet conduit 12 which projects
upwardly into the bottom portion of riser 2. A C.sub.3 -C.sub.4
rich hydrocarbon fraction may be introduced separately or with
steam by conduit 8 to the bottom portion of riser 2 for admixture
with hot regenerated catalyst. A suspension of catalyst in upflow
gasiform hydrocarbon material with or without steam provides a mix
temperature of at least 1100.degree.F. initially formed and passed
upwardly through an annular section of riser 2 about a gas oil
inlet means 12 under velocity conditions selected to provide a
hydrocarbon residence time as low as about one-tenth of a second up
to about 1 or 2 seconds. The upflowing initially formed suspension
in the annulus of riser 2 is thereafter combined with preheated
hydrocarbon feed such as a gas oil feed introduced by conduit 12
projecting upwardly into the bottom of riser 2. The thus formed
suspension at an elevated cracking temperature of at least
1000.degree.F. is caused to flow upwardly through the remaining
portion of the riser under hydrocarbon conversion conditions. On
the other hand, the gas oil feed may be introduced at spaced
intervals along the riser as by conduits 14 and 16. In yet another
embodiment it is contemplated initially lifting the hot regenerated
catalyst with steam or other inert gas before contact with the gas
oil feed introduced by conduit 12 for upward flow through the
riser. Additional gas oil feed may also be added downstream to the
thus formed suspension. Thereafter gaseous hydrocarbons rich in
C.sub.3 and C.sub.4 hydrocarbons are introduced to the upflowing
suspension by conduit 16 or a further downstream inlet conduit not
shown permitting a minimum residence time of about 1 second for low
temperature upgrading as herein described. In the arrangement of
the FIGURE, the suspension in riser 2 is discharged into cyclonic
separation zones 18 and 20 housed in the upper portion of vessel 22
wherein separation of catalyst from hydrocarbon vapors is
accomplished. Hydrocarbon vapors separated from catalyst then pass
into a plenum chamber 24 for removal from the vessel by conduit 26.
Catalyst separated from hydrocarbon vapors in cyclonic means 18 and
20 pass by diplegs 28 and 30 to a fluid bed of catalyst 32
maintained in the lower portion of the vessel 22. The fluid bed of
catalyst 32 is in open communication with a lower extending
stripping zone 34 therebelow to which the fluid bed of catalyst
moves generally downward countercurrent to rising stripping gas
introduced by conduit 36. The stripping zone is maintained at a
temperature within the range of 900.degree.F. to 1150.degree.F. and
the higher temperatures may be facilitated by the addition of hot
regenerated catalyst to the catalyst in the stripping zone by means
not shown. Stripped catalyst is removed from a bottom portion of
the stripping zone by conduit 38 for transfer to a catalyst
regeneration zone not shown. Stripped catalyst may also be recycled
to the riser inlet by conduit means not shown when it is desired to
provide catalyst to hydrocarbon ratios greater than 20 and as high
as about 80.
The fluid bed of catalyst 32 separated from the riser conversion
zone 2 is at an elevated temperature and may be in the range of
from about 900.degree.F. to about 1100.degree.F. As suggested
above, gaseous hydrocarbon feed such as a mixture of C.sub.3
-C.sub.4 hydrocarbons may be used to form a high temperature
suspension in a bottom portion of riser 2 by use of either conduit
12 or 8 alone or in combination with one another before gas oil is
introduced to a downstream portion of riser 2 as by one or both of
conduits 14 and 16. Also, as a means for controlling catalyst to
hydrocarbon ratios in the riser an inert gas may be initially
employed to form a suspension in a bottom portion of the riser into
which C.sub.4 and lighter hydrocarbons and gas oil are dispersed as
herein provided. The suspension formed will vary considerably in
temperature as herein provided and in catalyst/hydrocarbon ratio
but generally will be in the range of 10 to about 40.
The method and system of the FIGURE above described may be modified
considerably in operating combinations without departing from the
concepts of the present invention. In addition to the embodiments
above identified, riser 2 may be substantially external to vessel
22 and stripping zone 34 rather than pass upwardly through
substantially the center thereof. In this arrangement, the riser
relied upon to upgrade C.sub.4 and lower boiling hydrocarbons and
gas oil may be provided with additional hot freshly regenerated
catalyst in a downstream portion of the gas oil riser conversion
section. In one or more of the above defined embodiments, the
C.sub.4 and lower boiling gaseous feed components contact active
conversion catalyst of the faujasite type at a temperature within
the range of 700.degree.F. up to about 1100.degree.F. and the gas
oil feed contacts the faujasite catalyst preferably at temperatures
in excess of 900.degree.F. and as high as 1100.degree.F. In yet a
further embodiment it is contemplated employing a riser system in
which the gas oil feed initially forms a high temperature
catalyst/oil suspension in the bottom annular portion of the riser
about inlet conduit 12 through which dispersion steam is
introduced, additional gas oil feed may be added to the suspension
as by conduit 14 and a C.sub.4 rich stream may then be added to the
upflowing suspension as by conduit 16. In other words, lower
boiling gaseous hydrocarbons such as a C.sub.3 -C.sub.4 rich stream
is brought in contact with the gas oil-catalyst suspension in a
downstream or upper portion of the riser conversion zone.
DISCUSSION OF SPECIFIC EXAMPLE
A series of conversion runs with an isobutylene rich feed were made
under selected temperature and hydrocarbon residence time
conditions which support the improved operations contemplated by
the present invention and variations thereon. A catalyst comprising
15 percent REY was contacted under the conditions identified in the
table below which produced the results identified. It was observed
upon examination of the product that a considerable amount of
hydrogen transfer occurred along with the production of a
significant amount of liquid product. The liquid product was
identified as consisting chiefly of toluene, xylenes,
trimethylbenzenes and naphthalenes. Runs were made at a temperature
of 1050.degree.F. and 850.degree.F. using a wide spread in
hydrocarbon residence time.
TABLE
__________________________________________________________________________
Unit Hopper (dense bed) Riser (dilute phase, steady state) Run No.
180C- 193 194 195 196 197 Temp., .degree.F 1050.degree.
1050.degree. 1050.degree. 850.degree. 850.degree. .tau. gas, sec.
46 22 7 8 17 Cat/gas (wt/wt) 29 41 40 40 80
__________________________________________________________________________
Conversion (NLB): Unconv. butylene 5.4 8.7 17.4 29.3 27.4 31.7 9.1
14.6 Propylene 3.3 4.1 11.9 4.3 5.5 Isobutane 19.9 23.7 34.1 42.0
47.4 C.sub.5 + gaso. 3.3* 4.3* 19.8 13.8 17.3 Other C.sub.4 - gases
39.1 32.4 8.0 16.8 2.5 12.5 6.5 20.6 Coke 29.0 26.8 8.8 10.0 14.1
__________________________________________________________________________
*No liquid trap used
It will be observed from these data, that at the shorter residence
time used for the riser conversion runs, cracking of isobutylene to
lower molecular weight gases and to coke is much reduced. However,
at total conversion levels of 82.6, 67.8 and 90.9 percent of the
isobutylene, losses to undesirable products are 12.21 percent and
the ratios of isobutane to butylene plus propylene range from 1.15
to 3.25.
Thus run 195 effected at a high temperature and short residence
time supports a concept of the present invention where the hot
freshly regenerated catalysts initially contact the C.sub.3
-C.sub.4 rich feed in the lower portion of the riser reactor before
coming in contact with gas oil feed material. On the other hand,
run 196 supports a concept of this invention wherein previously
used catalyst reduced to a lower temperature is contacted in a
down-stream portion of the riser reactor with a C.sub.3 -C.sub.4
rich gaseous hydrocarbon feed material. Thus in any of the
operating embodiments herein contemplated and defined, a Y
faujasite conversion catalyst has activity and selectivity for
hydrogen transfer reaction and olefin cyclization reaction leading
to the production of significant quantities of isobutane and
aromatics.
In the method and system of this invention it is contemplated
processing hydrocarbon feed materials other than gas oil as
specifically discussed above. That is, it is contemplated
processing higher boiling residual oils, resids and hydrogenated
charge materials such as hydrogenated gas oils, and hydrogenated
resid.
Having thus generally described the method and means of the present
invention and discussed specific embodiments related thereto, it is
to be understood that no undue restrictions are to be imposed by
reason thereof except as defined by the following claims.
* * * * *