U.S. patent application number 12/134131 was filed with the patent office on 2009-12-10 for catalytic reforming process to produce high octane gasoline.
This patent application is currently assigned to Chevron U.S.A. Inc.. Invention is credited to Brian C. Adams, Cong-Yan Chen, Stephen Joseph Miller, James N. Ziemer.
Application Number | 20090301933 12/134131 |
Document ID | / |
Family ID | 41165127 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090301933 |
Kind Code |
A1 |
Miller; Stephen Joseph ; et
al. |
December 10, 2009 |
CATALYTIC REFORMING PROCESS TO PRODUCE HIGH OCTANE GASOLINE
Abstract
The present invention is a multistage reforming process to
produce high octane product from naphtha boiling range feed. In the
process, a effluent product from a penultimate reforming stage is
separated into at least a first stream and a second stream by
boiling point. The lower boiling of the two streams is further
reformed in a final reforming stage over a medium pore molecular
sieve catalyst.
Inventors: |
Miller; Stephen Joseph; (San
Francisco, CA) ; Chen; Cong-Yan; (Kensington, CA)
; Adams; Brian C.; (Berkeley, CA) ; Ziemer; James
N.; (Martinez, CA) |
Correspondence
Address: |
CHEVRON CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Assignee: |
Chevron U.S.A. Inc.
|
Family ID: |
41165127 |
Appl. No.: |
12/134131 |
Filed: |
June 5, 2008 |
Current U.S.
Class: |
208/64 |
Current CPC
Class: |
C10G 35/095 20130101;
C10G 59/02 20130101 |
Class at
Publication: |
208/64 |
International
Class: |
C10G 59/02 20060101
C10G059/02 |
Claims
1. A reforming process comprising: a. contacting a naphtha boiling
range feedstock in a penultimate stage of a multi-stage reforming
process at a first reforming pressure to produce a penultimate
effluent; b. separating at least a portion of the penultimate
effluent into at least an intermediate reformate and a heavy
reformate, wherein the intermediate reformate has a mid-boiling
point that is lower than that of the heavy reformate; and c.
contacting at least a portion of the intermediate reformate in a
final stage of the multi-stage reforming process at a second
reforming pressure with a catalyst comprising at least one medium
pore molecular sieve to produce a final effluent comprising a final
reformate, wherein the first reforming pressure is greater than the
second reforming pressure.
2. The process of claim 1, wherein the naphtha boiling range
feedstock boils in the range from about 50.degree. F. to about
550.degree. F.
3. The process of claim 1, wherein the intermediate reformate
comprises at least 70 vol % C.sub.5-C.sub.8 hydrocarbons.
4. The process of claim 3, wherein the intermediate reformate
comprises at least 70 vol % C.sub.6-C.sub.8 hydrocarbons.
5. The process of claim 1, wherein the heavy reformate comprises at
least 70 vol % C.sub.9+ hydrocarbons.
6. The process of claim 1, wherein the RON of the intermediate
reformate is higher than the RON of the naphtha boiling range
feedstock.
7. The process of claim 1, wherein the intermediate reformate has
an RON within the range of 65 to less than 100.
8. The process of claim 1, wherein the heavy reformate has an RON
of at least 95.
9. The process of claim 1, wherein at least 70 vol % of the final
reformate boils in the range of about 70.degree. F. or higher.
10. The process of claim 1, wherein the final reformate has an RON
of 90 or greater.
11. The process of claim 10, wherein the final reformate has an RON
which is greater than the RON of the intermediate reformate.
12. The process of claim 1, wherein the second reforming pressure,
of the final reforming stage, is within the range of 50 psig to 250
psig.
13. The process of claim 12, wherein the second reforming pressure,
of the final reforming stage, is within the range of 50 psig to 150
psig.
14. The process of claim 1, wherein the first reforming pressure,
of the penultimate reforming stage, is within the range of 70 psig
to 400 psig.
15. The process of claim 1, wherein the first reforming pressure is
within the range of 200 psig to 400 psig and within the second
reforming pressure is within the range of 50 psig to 150 psig.
16. The process of claim 1, wherein the catalyst within the
penultimate stage comprises a Group VIII metal and a prompter
supported on a porous refractory inorganic oxide support.
17. The process of claim 15, wherein the Group VIII metal is
platinum.
18. The process of claim 15 wherein the catalyst comprises platinum
and rhenium on an alumina support.
19. The process of claim 1, wherein the medium pore molecular sieve
is selected from the group consisting of ZSM-5, ZSM-11, ZSM-12,
ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48 MCM-22, SSZ-20, SSZ-25,
SSZ-32, SSZ-35, SSZ-37, SSZ-44, SSZ-45, SSZ-47, SSZ-57, SSZ-58,
SSZ-74, SUZ-4, EU-1, NU-85, NU-87, NU-88, IM-5, TNU-9, ESR-10,
TNU-10 and combinations thereof.
20. The process of claim 1, wherein the medium pore molecular sieve
comprises ZSM-5 having a silica to alumina molar ratio of at least
200:1.
21. The process of claim 1, wherein the medium pore molecular sieve
comprises ZSM-5 having a silica to alumina molar ratio of at least
500:1.
22. The process of claim 1, wherein the medium pore molecular sieve
comprises ZSM-5 having less than 5,000 ppm alkali.
23. The process of claim 1, wherein the catalyst in the final
reforming stage further comprises a Group VIII metal selected from
platinum or palladium.
24. The process of claim 1, further comprising blending the heavy
reformate with the final reformate to produce a fuel or a fuel
blend stock.
25. A reforming process comprising: a. contacting a naphtha boiling
range feedstock in a penultimate stage of a multi-stage reforming
process at a first reforming pressure to produce an penultimate
effluent; b. separating at least a portion of the penultimate
effluent into at least a light reformate, an intermediate reformate
and a heavy reformate, wherein the light reformate has a
mid-boiling point that is lower than that of the intermediate
reformate, and wherein the intermediate reformate has a mid-boiling
point that is lower than that of the heavy reformate; and c.
contacting at least a portion of the intermediate reformate in a
final stage of the multi-stage reforming process at a second
reforming pressure with a catalyst comprising at least one medium
pore molecular sieve to produce an final effluent comprising a
final reformate, wherein the first reforming pressure is greater
than the second reforming pressure.
26. The process of claim 24, wherein the light reformate comprises
at least 70 vol % C.sub.5 hydrocarbons.
27. The process of claim 24, wherein the intermediate reformate
comprises at least 70 vol % C.sub.5-C.sub.8 hydrocarbons.
28. The process of Claim 26, wherein the intermediate reformate
comprises at least 70 vol % C.sub.6-C.sub.8 hydrocarbons.
29. The process of claim 24, wherein the RON of the intermediate
reformate is higher than the RON of the naphtha boiling range
feedstock.
30. The process of claim 24, wherein the intermediate reformate has
ah RON of at least 65.
31. The process of claim 24, wherein the heavy reformate has an RON
of 95 or greater.
32. The process of claim 24, wherein the final reformate has an RON
of 90 or greater.
33. The process of claim 24, wherein the final reformate has an RON
which is greater than the RON of the intermediate reformate.
34. The process of claim 24, further comprising: a. separating the
final effluent into at least a final C.sub.5 stream and a final
reformate stream; b. combining the final C.sub.5 stream with the
light reformate stream; and c. combining the final reformate with
the heavy reformate.
35. The process of claim 33, wherein the final reformate stream
comprises at least 70 vol % C.sub.5+ hydrocarbons.
36. The process of claim 33, wherein the final reformate stream
comprises at least 70 vol % C.sub.6+ hydrocarbons.
37. The process of claim 33, wherein the final reformate stream
comprises at least 70 vol % C.sub.5-C.sub.8 hydrocarbons.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a multistage reforming
process using a medium pore molecular sieve catalyst to produce a
high octane naphtha at high liquid yield and hydrogen
production.
BACKGROUND OF THE INVENTION
[0002] Catalytic reforming is one of the basic petroleum refining
processes for upgrading light hydrocarbon feedstocks, frequently
referred to as naphtha feedstocks. Products from catalytic
reforming can include high octane gasoline useful as automobile
fuel, aromatics (for example benzene, toluene, xylenes and
ethylbenzene), and/or hydrogen. Reactions typically involved in
catalytic reforming include dehydrocylization, isomerization and
dehydrogenation of naphtha range hydrocarbons, with
dehydrocyclization and dehydrogenation of linear and slightly
branched alkanes and dehydrogenation of cycloparaffins leading to
the production of aromatics. Dealkylation and hydrocracking are
generally undesirable due to the low value of the resulting light
hydrocarbon products.
[0003] Catalysts commonly used in commercial reforming reactions
often include a Group VIII metal, such as platinum or palladium, or
a Group VIII metal plus a second catalytic metal, which acts as a
promoter. Examples of metals useful as promoters include rhenium,
tin, tungsten, germanium, cobalt, nickel, rhodium, ruthenium,
iridium or combinations thereof. The catalytic metal or metals may
be dispersed on a support such as alumina, silica, or
silica-alumina. Typically, a halogen such as chlorine is
incorporated on the support to add acid functionality. In addition
to Group VIII metals, other reforming catalysts include
aluminosilicate zeolite catalysts. For example, U.S. Pat. Nos.
3,761,389, 3,756,942 and 3,760,024 teach aromatization of a
hydrocarbon fraction with a ZSM-5 type zeolite catalyst. U.S. Pat.
No. 4,927,525 discloses catalytic reforming processes with beta
zeolite catalysis containing a noble metal and an alkali metal.
Other reforming catalysts include other molecular sieves such as
bore-silicates and silicoaluminophosphates, layered crystalline
clay-type phyllosilicates, and amorphous clays.
[0004] In addition to selection of catalysts for reforming, various
processes for reforming a naphtha feedstock in one or more process
steps to produce higher value reformate products are known in the
art. U.S. Pat. No. 3,415,737 teaches a process for reforming
naphtha under conventional mild reforming conditions with a
platinum-rhenium-chloride reforming catalyst to increase the
aromatics content and octane number of the naphtha. In U.S. Pat.
No. 3,770,614 there is disclosed a process in which a reformate is
fractionated and the light reformate fraction (C6 fraction) passed
over a ZSM-5-type zeolite to increase aromatic content of the
product. U.S. Pat. No. 3,950,241 discloses a process for upgrading
naphtha by separating it into low- and high-boiling fractions,
reforming the low-boiling fraction, combining the high-boiling
naphtha with the reformate, and contacting the combined fractions
with a ZSM-5-type catalyst. U.S. Pat. No. 4,181,599 discloses a
process for reforming naphtha comprising separating the naphtha
into heavy and light fractions and reforming and isomerizing the
naphtha fractions. U.S. Pat. No. 4,190,519 teaches a process for
upgrading a naphtha-boiling-range hydrocarbon which comprises
separating the naphtha feedstock into a light naphtha fraction
containing C6 paraffins and lower-boiling hydrocarbons and a heavy
naphtha fraction containing higher-boiling hydrocarbons, reforming
the heavy naphtha fraction and passing at least a portion of the
reformate together with the light naphtha fraction over a zeolite
catalyst to produce an aromatics-enriched effluent. Different
catalysts may be employed in different process steps during the
reforming of naphtha feedstocks as described in U.S. Pat. No.
4,627,909, U.S. Pat. No. 4,443,326, U.S. Pat. No. 4,764,267, U.S.
Pat. No. 5,073,250, U.S. Pat. No. 5,169,813, U.S. Pat. No.
5,171,691, U.S. Pat. No. 5,182,012, U.S. Pat. No. 5,358,631, U.S.
Pat. No. 5,376,259 and U.S. Pat. No. 5,407,558, for example.
[0005] Even with the advances in naphtha reforming catalysts and
processes, a need still exists to develop new and improved
reforming methods to provide higher liquid yield, improve hydrogen
production, and minimize the formation of less valuable low
molecule weight (C.sub.1-C.sub.4) products. It has been discovered
that interstage feed separation in a staged reforming process and
lower pressure in the final stage of a multistage reforming process
can improve the RON (Research Octane Number), aromatics content,
C.sub.5+ liquid yield, hydrogen production, and catalyst life.
SUMMARY OF THE INVENTION
[0006] The present invention relates to processes for catalytically
reforming a naphtha fuel feed to produce a product reformate in a
multistage reforming operation. The process comprises contacting a
naphtha boiling range hydrocarbon feedstock in a penultimate stage
of a multi-stage reforming process at a first reforming pressure to
produce a penultimate effluent; separating at least a portion of
the penultimate effluent into at least an intermediate reformate
and a heavy reformate, wherein the intermediate reformate has a
mid-boiling point that is lower than that of the heavy reformate;
and contacting the intermediate reformate in a final stage of the
multi-stage reforming process at a second reforming pressure with a
catalyst comprising at least one medium pore molecular sieve to
produce a final effluent comprising a final reformate, wherein the
first reforming pressure is greater than the second reforming
pressure.
[0007] In embodiments, the catalyst within the penultimate stage
comprises a Group VIII metal and a promoter supported on a porous
refractory inorganic oxide support. In embodiments, the catalyst
within the final stage comprises a Group VIII metal.
[0008] In another embodiment, a reforming process comprises
contacting a naphtha boiling range hydrocarbon feedstock in a
penultimate stage of a multi-stage reforming process at a first
reforming pressure to produce a penultimate effluent; separating at
least a portion of the penultimate effluent into at least a light
reformate, an intermediate reformate and a heavy reformate, wherein
the light reformate has a mid-boiling point that is lower than that
of the intermediate reformate, and wherein the intermediate
reformate has a mid-boiling point that is lower than that of the
heavy reformate; and contacting the intermediate reformate in a
final stage of the multi-stage reforming process at a second
reforming pressure with a catalyst comprising at least one medium
pore molecular sieve to produce a final effluent comprising a final
reformate, wherein the first reforming pressure is greater than the
second reforming pressure.
[0009] Other aspects, features and advantages will be apparent from
the description of the embodiments thereof and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic diagram of one embodiment of the
invention.
[0011] FIG. 2 is a schematic diagram of a second embodiment of the
invention.
DETAILED DESCRIPTION
[0012] In the present process, a naphtha boiling range hydrocarbon
feedstock is processed in a multi-Stage reforming process, which
process involves at least a penultimate stage for reforming the
naphtha feedstock to a penultimate stage naphtha product which has
an octane number higher than that of the naphtha feed and a final
stage for further reforming a portion of an effluent product from
the penultimate stage, producing a final naphtha having an octane
number higher than that of the penultimate stage naphtha product.
The reforming process is operated at conditions and with catalysts
selected for conducting dehydrocyclization, isomerization and
dehydrogenation reactions for converting low octane normal
paraffins and cycloparaffins into high octane materials. In this
way, a product having increased octane and/or containing an
increased amount of aromatics is produced. In some embodiments, the
multi-stage reforming process is operated at conditions and with
one more catalysts for producing a net positive quantity of
hydrogen.
[0013] The multi-stage reforming process comprises passing a
refinery stream through at least two reforming stages in series. In
general, each reforming stage is characterized by one or more
reforming reactor vessels, each containing a catalyst and
maintained at reforming reaction conditions. The product from each
stage before the final stage is passed, in whole or in part, to the
succeeding stage in the multi-stage process. The temperature of the
product from each stage which is passed to a succeeding stage may
be increased or decreased to meet the particular needs of the
process. Likewise, the pressure of the product which is passed to a
succeeding stage before the final stage may be increased or
decreased, with the proviso that the pressure in the penultimate
stage is higher than the pressure in the final stage.
[0014] While the discussion which follows relates at times, for
convenience, to operation of penultimate and final reforming
stages, the principles of the invention are applicable as between
any two successive stages and can be applied to several
sequentially connected stages. In essence then, the term final
stage as used herein does not necessarily indicate the last stage
if there are three or more stages, but father indicates a
succeeding stage which follows a preceding (often referred to for
convenience as "penultimate") stage.
DEFINITIONS
[0015] As disclosed herein, boiling point temperatures are based on
ASTM D-2887 standard test method for boiling range distribution of
petroleum fractions by gas chromatography, unless otherwise
indicated. The mid-boiling point is defined as the 50% by volume
boiling temperature, based on an ASTM D-2887 simulated
distillation.
[0016] As disclosed herein, carbon number values (i.e. C.sub.5,
C.sub.6, C.sub.8, C.sub.9 and the like) of hydrocarbons may be
determined by standard gas chromatography methods. Unless otherwise
specified, Research Octane Number (RON) is determined using the
method described in ASTM D2699.
[0017] Unless otherwise specified, feed rate to a catalytic
reaction zone is reported as the volume of feed per volume of
catalyst per hour. In effect, the feed rate as disclosed herein,
referred to as liquid hourly space velocity (LHSV), is reported in
reciprocal hours (i.e. hr.sup.-1).
[0018] As used herein, a C.sub.1- stream comprises a high
proportion of hydrocarbons with 4 or fewer carbon atoms per
molecule. Likewise, a C.sub.5+ stream comprises a high proportion
of hydrocarbons with 5 or more carbon atoms per molecule. It will
be recognized by those of skill in the art that hydrocarbon streams
in refinery processes are generally separated by boiling range
using a distillation process. As such, the C.sub.4- stream would be
expected to contain a small quantity of C.sub.5, C.sub.6 and even
C.sub.7 molecules. However, a typical distillation would be
designed and operated such that at least about 70% by volume of a
C.sub.4- stream would contain molecules having 4 carbon atoms or
fewer per molecule. As used herein, C.sub.5+, C.sub.6-C.sub.8,
C.sub.9+ and other hydrocarbon fractions identified by carbon
number ranges would be interpreted likewise.
[0019] The term "silica to alumina ratio" refers to the molar ratio
of silicon oxide (SiO.sub.2) to aluminum oxide
(Al.sub.2O.sub.3).
[0020] As used herein the term "molecular sieve" refers to a
crystalline material containing pores, cavities, or interstitial
spaces of a uniform size in which molecules small enough to pass
through the pores, cavities, or interstitial spaces are adsorbed
while larger molecules are not. Examples of molecular sieves
include zeolites and non-zeolitic molecular sieves such as zeolite
analogs including, but not limited to, SAPOs
(silicoaluminophosphates), MeAPOs (metalloaluminophosphates),
AlPO.sub.4, and ELAPOs (nonmetal substituted aluminophosphate
families).
[0021] When used in this disclosure, the Periodic Table of the
Elements referred to is the CAS version published by the Chemical
Abstract Service in the Handbook of Chemistry and Physics,
72.sup.nd edition (1991-1992).
[0022] Among other factors, the present invention is based on the
discovery that selective reforming of paraffins, especially
C.sub.6-C.sub.8 paraffins, in a separate or additional reforming
stage provides improved performance of the overall reforming
process. Thus, a penultimate reforming stage using a conventional
reforming catalyst is operated at relatively low severity, since it
is not required to reach the high octane levels normally desired
for a naphtha fuel or fuel blend stock. Under these conditions the
catalyst catalyzes the more facile reactions, such as cyclohexane
and alkycyclohexane dehydrogenation, while keeping hydrocracking to
a minimum. Generally, a conventional catalyst used to
dehydrocyclize paraffins under more severe conditions produces
higher quantities of light gases, on account of the catalyst being
somewhat unselective for dehydrocyclization. With the present
invention, however, an intermediate reformate from a penultimate
reforming stage is passed to a final reforming stage containing a
medium pore molecular sieve catalyst. The performance
characteristics of the medium pore molecular sieve catalyst permits
operating a final stage in the multi-stage reforming process at a
reduced pressure, which increases the selectivity of
C.sub.6-C.sub.8 paraffin dehydrocyclization while maintaining low
catalyst fouling rates. The C.sub.9+ fraction from the penultimate
stage has higher octane than the C.sub.6-C.sub.8 intermediate
fraction, and is not further reformed in the final stage.
Otherwise, the high octane C.sub.9+ fraction from the penultimate
stage will undergo some cracking and/or dealkylation reactions in
the final stage, which lowers the liquid yield and consumes
hydrogen. Consequently, the performance characteristics of the
catalyst of the final stage provide complementary benefits,
resulting in an overall process which produces a high octane
product at ah improved liquid yield and hydrogen production.
[0023] The naphtha boiling range feedstock entering the penultimate
stage of the multi-stage process is a naphtha fraction boiling
within the range from about of 50.degree. to about 550.degree. F.
and preferably from 70.degree. to 450.degree. F. In embodiments,
the reformer feed is a C.sub.5+ feed. The reformer feed can
include, for example, straight run naphthas, paraffinic raffinates
from aromatic extraction or adsorption, and C.sub.6-C.sub.10
paraffin-rich feeds, bioderived naphtha, naphtha from hydrocarbon
synthesis processes, including Fischer Tropsch and methanol
synthesis processes, as well as naphtha products from other
refinery processes, such as hydrocracking or conventional
reforming. In reforming processes involving more than two stages,
the reformer feed may comprise at least a portion of the product
generated in a preceding stage.
[0024] The reforming catalyst used in the penultimate reforming
stage may be any catalyst known to have catalytic reforming
activity. In embodiments, the penultimate stage catalyst comprises
a Group VIII metal disposed on an oxide support. Example Group VIII
metals include platinum and palladium. The catalyst may further
comprise a promoter, such as rhenium, tin, germanium, cobalt,
nickel, iridium, tungsten, rhodium, ruthenium, or combinations
thereof. In some such embodiments, the promoter metal is rhenium or
tin. These metals are disposed on a support, such as alumina,
silica/alumina, or silica. In some such embodiments, the support is
alumina. The support may also include natural or man-made zeolites.
The catalyst may also include between 0.1 and 3 weight percent
chloride, preferably between 0.5 and 1.5 weight percent chloride.
The catalyst, if it includes a promoter metal, suitably includes
sufficient promoter metal to provide a promoter to platinum ratio
between 0.5:1 and 10:1 or between 1:1 and 6:1. The precise
conditions, compounds, and procedures for catalyst manufacture are
known to those persons skilled in the art. Some examples of
conventional catalysts are shown in U.S. Pat. Nos. 3,631,216;
3,415,737; and 4,511,746, which are hereby incorporated by
reference in their entireties.
[0025] The catalysts in both the penultimate stage and the final
stage may be employed in the form of pills, pellets, granules,
broken fragments, or various special shapes, disposed as a fixed
bed within a reaction zone, and the charging stock may be passed
therethrough in the liquid, vapor, or mixed phase, and in either
upward, downward or radial flow. Alternatively, they can be used in
moving beds or in fluidized-solid processes, in which the charging
stock is passed upward through a turbulent bed of finely divided
catalyst. However, a fixed bed system or a dense-phase moving bed
system are preferred due to the lower catalyst attrition losses and
other operational advantages. In a fixed bed system, the feed is
preheated (by any suitable heating means) to the desired reaction
temperature and then passed into a reaction zone containing a fixed
bed of the catalyst. This reaction zone may be one or more separate
reactors with suitable means to maintain the desired temperature at
the reactor entrance. The temperature must be maintained because
reforming reactions are typically endothermic in nature.
[0026] The actual reforming conditions in both the penultimate and
the final reforming stages will depend, at least in part, on the
feed used, whether highly aromatic, paraffinic or naphthenic and
upon the desired octane rating of the product and desired hydrogen
production.
[0027] The penultimate stage is maintained at relatively mild
reaction conditions, so as to inhibit the cracking of the stream
being upgraded, and to increase the useful lifetime of the catalyst
in the penultimate stage. The naphtha boiling range feedstock to be
upgraded in the penultimate stage contacts the penultimate stage
catalyst at reaction conditions, which conditions include a
temperature in the range from about 800.degree. F. to about
1100.degree. F., a pressure in the range from greater than 70 psig
to about 400 psig, and a feed rate in the range of from about 0.5
hr.sup.-1 to about 5 hr.sup.-1 LHSV. In some embodiments, the
pressure in the penultimate stage is in the range from about 200
psig to about 400 psig.
[0028] The effluent from the penultimate stage is an upgraded
product, in that the RON has been increased during reaction in the
penultimate stage. The penultimate stage effluent comprises
hydrocarbons and hydrogen generated during reaction in the
penultimate stage and at least some of the hydrogen, if any, which
is added to the feed upstream of the penultimate stage. The
effluent hydrocarbons may be characterized as a mixture of C.sub.4-
hydrocarbons and C.sub.5+ hydrocarbons, the distinction relating to
the molecular weight of the hydrocarbons in each group. In
embodiments, the C.sub.5+ hydrocarbons in the effluent have a
combined RON of at least 85.
[0029] The effluent from the penultimate stage (otherwise termed
the "penultimate-effluent") comprises C.sub.5+ hydrocarbons which
are separated into at least an intermediate reformate and a heavy
reformate. The effluent further comprises hydrogen and C.sub.4-
hydrocarbons. A hydrogen-rich stream may separate from the effluent
in a preliminary separation step, using, for example, a high
pressure separator or other flash zone. C.sub.4- hydrocarbons in
the effluent may also be separated in a preliminary separation,
either along with the hydrogen or in a subsequent flash zone. The
intermediate reformate is characterized as having a lower
mid-boiling point than that of the heavy reformate. In some
embodiments, the intermediate reformate boils in the range from
about 70.degree. F. to about 280.degree. F. In some such
embodiments, the intermediate reformate comprises at least 70 vol %
C.sub.5-C.sub.9 hydrocarbons. In some embodiments, the intermediate
reformate boils in the range from about 100.degree. F. to about
280.degree. F. In some such embodiments, the intermediate reformate
comprises at least 70 vol % C.sub.6-C.sub.8 hydrocarbons. In some
embodiments, the intermediate reformate boils in the range from
about 100.degree. F. to about 230.degree. F. In some such
embodiments, the intermediate reformate comprises at least 70 vol %
C.sub.6-C.sub.7 hydrocarbons. Recovery of an intermediate reformate
fraction may be accompanied by the further recovery of a largely
C.sub.5 light reformate fraction. The light reformate is
characterized as having a lower mid-boiling point than that of the
intermediate reformate. In some embodiments, the light reformate
fraction boils in the range from about 70.degree. F. to about
140.degree. F. In some such embodiments, the light reformate
fraction comprises at least 70 vol % C.sub.5 hydrocarbons. The
heavy reformate that is produced during separation of the upgraded
product boils in the range of about 220.degree. F. and higher. In
some such embodiments, the heavy reformate comprises at least 70
vol % C.sub.9+ hydrocarbons.
[0030] The RON of the intermediate reformate is indicative of the
mild reforming conditions in the penultimate stage. As such, the
intermediate reformate typically has an RON of greater than 65. In
some embodiments the intermediate reformate has an RON within the
range of about 65 to less than 100. In some such embodiments the
intermediate reformate has an RON within the range of 65 to less
than 95.
[0031] The final stage reforming catalyst comprises at least one
medium pore molecular sieve. The molecular sieve is a porous
inorganic oxide characterized by a crystalline structure which
provides pores of a specified geometry, depending on the particular
structure of each molecular sieve. The phrase "medium pore" as used
herein means having a crystallographic free diameter in the range
of from about 3.9 to about 7.1 Angstrom when the porous inorganic
oxide is in the calcined form. The crystallographic free diameters
of the channels of molecular sieves are published in the "Atlas of
Zeolite Framework Types", Fifth Revised Edition, 2001, by Ch.
Baerlocher, W. M. Meier, and D. H. Olson, Elsevier, pp 10[ndash]15,
which is incorporated herein by reference. Non-limiting examples of
medium pore molecular sieves include ZSM-5, ZSM-11, ZSM-12, ZSM-22,
ZSM-23, ZSM-35, ZSM-38, ZSM-48 MCM-22, SSZ-20, SSZ-25, SSZ-32,
SSZ-35, SSZ-37, SSZ-44, SSZ-45, SSZ-47, SSZ-57, SSZ-58, SSZ-74,
SUZ-4, EU-1, NU-85, NU-87, NU-88, IM-5, TNU-9, ESR-10, TNU-10 and
combinations thereof. As used in this disclosure, the medium pore
molecular sieve useful in the present process is a high silica
ZSM-5 zeolite with a molar ratio of SiO.sub.2/M.sub.2O.sub.3 of at
least 40:1, preferably at least 200:1 and more preferably at least
500:1, where M is selected from Al, B, or Ga.
[0032] Various references disclosing ZSM-5 are provided in U.S.
Pat. No. 4,401,555 to Miller. These references include the
aforesaid U.S. Pat. No. 4,061,724 to Grose et al.; U.S. Pat.
Reissue No. 29,948 to Dwyer et al.; Flanigan et al., Nature, 271,
512-516 (Feb. 9, 1978) which discusses the physical and adsorption
characteristics of high silica ZSM-5. Anderson et al., J. Catalysis
58, 114-130 (1979) which discloses catalytic reactions and sorption
measurements carried out on ZSM-5. The disclosures of these
references, and U.S. Pat. No. 4,401,555, are incorporated herein by
reference, particularly including their disclosures on methods of
making high silica to alumina ZSM-5. Additional disclosure on the
preparation and properties of high silica ZSM-5 may be found, for
example, in U.S. Pat. No. 5,407,558 and U.S. Pat. No.
5,376,259.
[0033] In embodiments, the high silica ZSM-5 molecular sieve which
is useful as a component of the catalyst in the present process has
a molar silica to alumina molar ratio of at least 40:1, or at least
200:1, or at least 500:1. An example high silica molecular sieve
has a silica to alumina molar ratio of at least 1000:1. In
embodiments, the molecular sieve is characterized as having a
crystallite size less than 10 .mu.m, or less than 5 .mu.m or less
than 1 .mu.m. Methods for determining crystallite size, using, for
example Scanning Electron Microscopy, are well known. In
embodiments, the high silica ZSM-5 is characterized as having at
least 80% crystallinity, or at least 90% crystallinity, or at least
95% crystallinity. Methods for determining crystallinity, using,
for example, X-ray Diffraction, are well known. Strong acidity is
undesirable in the catalyst because it promotes cracking, resulting
in lower selectivity to C.sub.5+ liquid product. To reduce acidity,
the molecular sieve preferably contains an alkali metal and/or an
alkaline earth metal. The alkali or alkaline earth metals are
preferably incorporated into the catalyst during or after synthesis
of the molecular sieve. Preferably, at least 90% of the acid sites
are neutralized by introduction of the metals, more preferably at
least 95%, most preferably at least 99%. In one embodiment, the
medium pore molecular sieve has less than 5,000 ppm alkali. Such
medium pore silicate molecular sieves are disclosed, for example,
in U.S. Pat. No. 4,061,724 and in U.S. Pat. No. 5,182,012. These
patents are incorporated herein by reference, particularly with
respect to the description, preparation and analysis of molecular
sieves having the specified molar silica to alumina molar ratios,
having a specified crystallite size, having a specified
crystallinity and having a specified alkali content.
[0034] Other crystalline molecular sieves which can be used in the
final reforming stage, include those as listed in U.S. Pat. No.
4,835,336, namely, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-38,
ZSM-48, and other similar materials such as CZH-5 disclosed in Ser.
No. 166,863 of Hickson, filed Jul. 7, 1980 and incorporated herein
by reference.
[0035] SSZ-20 is disclosed in U.S. Pat. No. 4,483,835, and SSZ-23
is disclosed in U.S. Pat. No. 4,859,442, both of which are
incorporated herein by reference.
[0036] ZSM-5 is more particularly described in U.S. Pat. No.
3,702,886 and U.S. Pat. Re. 29,948, the entire contents of which
are incorporated herein by reference.
[0037] ZSM-11 is more particularly described in U.S. Pat. No.
3,709,979, the entire contents of which are incorporated herein by
reference.
[0038] ZSM-12 is more particularly described in U.S. Pat. No.
3,832,449, the entire contents of which are incorporated herein by
reference.
[0039] ZSM-22 is more particularly described in U.S. Pat. Nos.
4,481,177, 4,556,477 and European Pat. No. 102,716, the entire
contents of each being expressly incorporated herein by
reference.
[0040] ZSM-23 is more particularly described in U.S. Pat. No.
4,076,842, the entire contents of which are incorporated herein by
reference.
[0041] ZSM-35 is more particularly described in U.S. Pat. No.
4,016,245, the entire contents of which are incorporated herein by
reference.
[0042] ZSM-38 is more particularly described in U.S. Pat. No.
4,046,859, the entire contents of which are incorporated herein by
reference.
[0043] ZSM-48 is more particularly described in U.S. Pat. No.
4,397,827 the entire contents of which are incorporated herein by
reference.
[0044] The crystalline molecular sieve may be in the form of a
borosilicate, where boron replaces at least a portion of the
aluminum of the more typical aluminosilicate form of the molecular
sieve. Borosilicate molecular sieves are described in U.S. Pat.
Nos. 4,268,420; 4,269,813; 4,327,236 to Klotz, the disclosures of
which patents are incorporated herein, particularly those
disclosures related to borosilicate preparation.
[0045] Silicoaluminophosphates (SAPOs) are an example of
nonzeolitic molecular sieves useful in the practice of the present
invention. SAPOs comprise a molecular framework of corner-sharing
[SiO.sub.4] tetrahedra, [AlO.sub.4] tetrahedra and [PO.sub.4]
tetrahedra linked by oxygen atoms. By varying the ratio of P/Al and
Si/Al the acidity of the SAPO can be modified to minimize unwanted
hydrocracking and maximize advantageous isomerization reactions.
Preferred molar ratios of P/Al are from about 0.75 to 1.3 and
preferred molar ratios of Si/Al are from about 0.08 to 0.5.
Examples of a silcoaluminophosphate useful to the present invention
include SAPO-11, SAPO-31, and SAPO-41, which are also disclosed in
detail in U.S. Pat. No. 5,135,638.
[0046] The catalysts used in the final reforming stage according to
the present invention contain one or more Group VIII metals, e.g.,
nickel, ruthenium, rhodium, palladium, iridium or platinum. The
preferred Group VIII metals are iridium, palladium, and
particularly platinum. They are more selective with regard to
dehydrocyclization and are also more stable under the
dehydrocyclization reaction conditions than other Group VIII
metals. The preferred percentage of the Group VIII metals, such as
platinum, in the catalyst is between 0.1 wt. % and 5 wt. %, more
preferably from 0.3 wt. % to 2.5 wt. %. The catalyst may further
comprise a promoter, such as rhenium, tin, germanium, cobalt,
nickel, iridium, tungsten, rhodium, ruthenium, or combinations
thereof.
[0047] In forming the final stage catalyst, the crystalline zeolite
is preferably bound with a matrix. The matrix is not catalytically
active for hydrocarbon cracking. Satisfactory matrices include
inorganic oxides, including alumina, silica, naturally occurring
and conventionally processed clays, such as bentonite, kaolin,
sepiolite, attapulgite and halloysite. Such materials have few, if
any, acid sites and therefore have little or no cracking
activity.
[0048] Reaction conditions in the final reforming stage are
specified to effectively utilize the particular performance
advantages of the catalyst used in the stage. Thus, in the process
of the invention, the reaction pressure of the final reforming
stage is less than the pressure in the penultimate stage. Operating
the final reforming stage at a lower pressure is made possible, at
least in part, by the high catalytic stability of the medium pore
molecular sieve catalyst of the present invention, which permits
the catalyst to operate at lower pressures without significant
fouling and premature activity failure. This in turn, permits the
operation of the penultimate stage at relatively mild conditions,
providing long catalyst life and high yields of hydrogen and
desired high octane products.
[0049] The naphtha feed to the final stage is the intermediate
reformate which is separated from the effluent of the penultimate
stage. In the process, the intermediate reformate contacts the
catalyst in the final stage at reforming reaction conditions, which
reaction conditions include a temperature in the range from about
800.degree. F. to about 1100.degree. F., a pressure in the range
from about 50 psig to about 250 psig and a feed rate in the range
of from about 0.5 hr.sup.-1 to about 5 hr.sup.-1 LHSV. In some
embodiments, the pressure in the reforming stage is less than 100
psig. Hydrogen may be added as an additional feed to the final
reforming stage, but it is not required. In embodiments, hydrogen
added with the feed is recovered from the process for separating
the final stage effluent and is recycled to the final stage. The
final stage is operated at conditions to maintain a molar
H.sub.2/hydrocarbon ratio in the range of 1:1 to 10:1. A molar
H.sub.2/hydrocarbon ratio in the range of 1:1 to 4:1 is
exemplary.
[0050] Depending on the particular process, the effluent (otherwise
termed the "final effluent") from the final reforming stage may
contain light (i.e. C.sub.4- products and/or hydrogen) products
which may be removed from the reformate in a final separation step
prior to further processing for blending or use as a fuel. A
hydrogen-rich stream may be separated from the effluent prior to
the separation step, using, for example, a high pressure separator
or other flash zone. C.sub.4- hydrocarbons in the effluent may also
be separated in a preliminary flash zone, either along with the
hydrogen or in a subsequent flash zone. The reformate which is
produced in the final reforming stage has an increased RON relative
to that of the intermediate reformate which is the feed to the
final reforming stage. In embodiments, the RON of the final
reformate is at least 90 or at least 95, or at least 98. In some
embodiments, the final reformate boils in the range from about
70.degree. F. to about 280.degree. F. In some such embodiments, the
final reformate comprises at least 70 vol % C.sub.5-C.sub.8
hydrocarbons. In some embodiments, the final reformate boils in the
range from about 100.degree. F. to about 280.degree. F. In some
such embodiments, the final reformate comprises at least 70 vol %
C.sub.6-C.sub.8 hydrocarbons. In some embodiments, the final
reformate boils in the range from about 100.degree. F. to about
230.degree. F. In some such embodiments, the final reformate
comprises at least 70 vol % C.sub.6-C.sub.7 hydrocarbons. In
addition to the final reformate stream, a final light stream may
also be recovered from the final effluent. In such cases, the final
light stream boils in the range of about 70.degree. to about
140.degree. F. In some such embodiments, the final light stream
comprises at least 70 vol % C.sub.5 hydrocarbons.
[0051] The reformate is useful as a fuel or as a blend stock for a
fuel. In some embodiments, at least a portion of the reformate from
the final reforming stage is blended with at least a portion of the
heavy reformate, which is recovered from the penultimate reforming
stage; the blend may be used as a fuel or as a blend stock for a
fuel.
[0052] Reference is now made to an embodiment of the invention
illustrated in FIG. 1. A naphtha boiling range fraction 5 which
boils within the range of 50.degree. F. to 550.degree. F. passes
into the reaction stage 10 at a feed rate in the range of about 0.5
hr.sup.-1 to about 5 hr.sup.-1 LHSV. Reaction conditions in the
reforming stage 10 include a temperature in the range from about
800.degree. F. to about 1100.degree. F. and a total pressure in the
range of greater than 70 psig to about 400 psig.
[0053] The effluent 11 from the penultimate stage is an upgraded
product, in that the RON has been increased during reaction in the
penultimate stage 10. The penultimate stage effluent 11 comprises
hydrocarbons and hydrogen generated during reaction in the
penultimate stage and at least some of the hydrogen (if any) added
to the feed upstream of the penultimate stage. In the embodiment
illustrated in FIG. 1, the effluent is separated in separation zone
20 into a hydrogen-rich stream 21, a C.sub.4-stream 22, an
intermediate reformate 25 and a heavy reformate 26. In embodiments,
this separation occurs in a single separation zone. In other
embodiments, this separation is done in sequential zones, with the
hydrogen, and optionally the C.sub.4-stream, separated in one or
more preliminary separation zones prior to the separation of the
intermediate reformate 25 and the heavy reformate 26.
[0054] In the embodiment illustrated in FIG. 1, the intermediate
reformate 25 comprises a substantial amount of the C.sub.5-C.sub.8
hydrocarbons contained in the effluent, with smaller quantities of
C.sub.4 and C.sub.9 hydrocarbons. At least a portion of
intermediate reformate 25 is passed to final reforming stage 30.
Heavy reformate 26 contains a substantial amount of the C.sub.9+
hydrocarbons contained in the effluent 11, and has an RON of
greater than 98, preferably greater than 100.
[0055] Intermediate reformate 25 is passed to final reforming stage
30 for contact with a catalyst comprising platinum and at least one
medium pore molecular sieve, at reaction conditions which include a
temperature in the range from about 800.degree. F. to about
1100.degree. F. and a pressure in the range from about 50 psig to
about 250 psig.
[0056] Effluent 31 from the final reforming stage is separated in
separation zone 40, yielding at least a hydrogen-rich stream 41, a
C.sub.4- stream 42, and a final reformate stream 45. In
embodiments, the final reformate stream boils in the C.sub.5+
boiling range. As described above, this separation may take place
in one, or multiple, separation zones, depending on the specific
requirements of a particular process. In an embodiment, the final
reformate stream 45 may be further combined with the heavy
reformate 26 before further processing or use as a fuel or fuel
blend stock. Hydrogen-rich stream 41 is combined with hydrogen-rich
stream 21 before using in other refinery processes, and C.sub.4-
stream 42 is combined with C.sub.4- stream 22.
[0057] Reference is now made to an embodiment of the invention
illustrated in FIG. 2. A naphtha boiling range fraction 5 which
boils within the range of 50 F..degree. to 550.degree. F. passes
into the reaction stage 10 at a feed rate in the range of about 0.5
hr.sup.-1 to about 5 hr.sup.-1 LHSV. Reaction conditions in the
reforming stage 10 include a temperature in the range from about
800.degree. F. to about 1100.degree. F. and a total pressure in the
range of greater than 70 psig to about 400 psig.
[0058] The effluent 11 from the penultimate stage is an upgraded
product, in that the RON has been increased during reaction in the
penultimate stage 10. The penultimate stage effluent 11 comprises
hydrocarbons and hydrogen generated during reaction in the
penultimate stage and at least some of the hydrogen (if any) added
to the feed upstream of the penultimate stage. In the embodiment
illustrated in FIG. 2, the effluent is separated in separation zone
20 into a hydrogen-rich stream 21, a C.sub.4- stream 22, a light
reformate 23, an intermediate reformate 24 and a heavy reformate
26. In embodiments, this separation occurs in a single separation
zone. In other embodiments, this separation is done in sequential
zones, with the hydrogen, and optionally the C.sub.4- stream,
separated in one or more preliminary separation zones prior to the
separation of the light reformate 23, the intermediate reformate 24
and the heavy reformate 26.
[0059] In the embodiment illustrated in FIG. 2, the light reformate
23 comprises a substantial amount of the C.sub.5 hydrocarbons
contained in the effluent, with smaller quantities of C.sub.4 and
C.sub.6 hydrocarbons. The intermediate stream comprises a
substantial portion of the C.sub.6-C.sub.8 hydrocarbons contained
in the effluent; the heavy reformate 26 contains a substantial
amount of the C.sub.9+ hydrocarbons contained in the effluent
11.
[0060] Intermediate reformate 24 is passed to final reforming stage
30 at a feed rate in the range of from about 0.5 hr.sup.-1 to about
5 hr.sup.-1 LHSV, for contact with a catalyst comprising platinum
and at least one medium pore molecular sieve, at reaction
conditions which include a temperature in the range from about
800.degree. F. to about 1100.degree. F. and a pressure in the range
from about 50 psig to about 250 psig.
[0061] Effluent 31 from the final reforming stage is separated in
separation zone 40, yielding at least a hydrogen-rich stream 41, a
C.sub.4- stream 42, a final C.sub.5 stream 43 and a final reformate
stream 44. In embodiments, the final reformate stream boils in the
C.sub.6+ boiling range. As described above, this separation may
take place in one, or multiple, separation zones, depending on the
specific requirements of a particular process. As shown in the
embodiment illustrated in FIG. 2, the final reformate stream 44 is
further combined with the heavy reformate 26 before further
processing or use as a fuel or fuel blend stock, hydrogen-rich
stream 41 is combined with hydrogen-rich stream 21 before using in
other refinery processes, C.sub.4- stream 42 is combined with
C.sub.4- stream 22 and final C.sub.5 stream 43 is combined with
C.sub.5 stream 23.
[0062] The following examples are presented to exemplify
embodiments of the invention but are not intended to limit the
invention to the specific embodiments set forth. Unless indicated
to the contrary, all parts and percentages are by weight. All
numerical values are approximate. When numerical ranges are given,
it should be understood that embodiments outside the stated ranges
may still fall within the scope of the invention. Specific details
described in each example should not be construed as necessary
features of the invention.
EXAMPLES
Example 1
[0063] A naphtha feed, with an API of 54.8, RON of 53.3 and an ASTM
D-2887 simulated distillation shown in Table 1 was reformed in a
penultimate stage using a commercial reforming catalyst comprising
platinum with a rhenium promoter on an alumina support. Reaction
conditions included a temperature of 840.degree. F., a pressure of
200 psig, a 5:1 molar ratio of hydrogen to hydrocarbon ratio and a
feed rate of 1.43 hr.sup.-1 LHSV. The C.sub.5+ liquid yield was
92.7 wt %. The hydrogen production was 975 standard cubic feet per
barrel feed.
[0064] This C.sub.5+ liquid product collected from the penultimate
stage had an API of 46.6, an RON of 89 and an ASTM D-2887 simulated
distillation as given in Table 2.
TABLE-US-00001 TABLE 1 ASTM D-2887 Simulated Distillation of the
Feed to the Penultimate Stage Vol. % Temperature, .degree. F. IBP
182 10 199 30 227 50 258 70 291 90 336 EP 386
TABLE-US-00002 TABLE 2 ASTM D-2887 Simulated Distillation of the
C.sub.5+ Liquid Product Collected from the Penultimate Stage Vol. %
Temperature, .degree. F. IBP 165 10 189 30 234 50 257 70 289 90 336
EP 411
Example 2
[0065] The C.sub.5+ liquid product from Example 1 was distilled
into an intermediate reformate and a heavy reformate. The
intermediate reformate was found to represent 80 vol. % of the
C.sub.5+ liquid product from Example 1. The intermediate reformate,
having an API of 55.7, an RON of 85 and an ASTM D-2887 simulated
distillation as shown in Table 3, was used as feed to a final
reforming stage in Example 3 and Comparative Example 1. The heavy
reformate was found to represent 20 vol. % of the C.sub.5+ liquid
product from Example, 1. The heavy reformate had an API of 28.9 and
an RON of 105, and is further described in Table 5.
TABLE-US-00003 TABLE 3 ASTM D-2887 Simulated Distillation of the
Intermediate Reformate from the Penultimate Reforming Stage Vol. %
Temperature, .degree. F. IBP 168 10 190 30 235 50 240 70 284 90 296
EP 336
Example 3
[0066] The intermediate reformate produced in Example 2 was used as
feed to the final reforming stage which used a ZSM-5 zeolite based
catalyst composited with 35% alumina binder material. The ZSM-5 had
a SiO2/Al2O3 molar ratio of .about.2000 and was ion exchanged to
the ammonium form before incorporating in a 65% zeolite/35% alumina
extrudate. The extrudate was impregnated with 0.8% Pt, 0.3% Na, and
0.3% Mg by an incipient wetness procedure to make the final
catalyst. The reaction conditions and experimental results are
listed in Table 4.
TABLE-US-00004 TABLE 4 Comparison of the results from Example 3 and
Comparative Example 1 Example 3 Comparative Example 1 Catalyst
Pt/Na/Mg/ZSM-5 Pt/Re with alumina binder with alumina binder
Temperature, .degree. F. 900 950 910 940 Pressure, psig 80 80 200
200 LHSV, hr.sup.-1 1.5 1.5 1.5 1.5 Molar H.sub.2/hydrocarbon 2:1
2:1 5:1 5:1 Ratio RON of C.sub.5+ 97.0 100.6 96.9 101.8 C.sub.5+
Yield, wt % 92.7 88.4 88.9 85.2 H.sub.2 Yield, scf/bbl feed 300 430
130 175
Comparative Example 1
[0067] The intermediate reformate produced in Example 2 was
contacted with a commercial platinum/rhenium on alumina based
catalyst described in Example 1 in a final reforming stage. The
reaction conditions and experimental results are listed in Table 4
and compared with the results from Example 3 which uses a ZSM-5
zeolite based catalyst.
[0068] Example 3 and Comparative Example 1 show the benefit of
ZSM-5 zeolite based catalysts when compared with commercial
platinum on alumina catalysts in terms of C.sub.5+ yield and
hydrogen production at similar C.sub.5+ RON.
Example 4
[0069] A product which was produced in the final stage reforming of
the intermediate reformate in Example 3 was blended with the heavy
reformate (Example 2) which was not subjected to the final stage
reforming. The total RON of C.sub.5+, total C.sub.5+ yield and
total H.sub.2 production of the blended final product are given in
Table 5 based on using the total C.sub.5+ penultimate effluent as
feed (which is distilled into intermediate reformate and heavy
reformate in Example 2). The results are compared to those obtained
from Comparative Example 2 where the total C.sub.5+ product was
produced from the total C.sub.5+ penultimate effluent as feed,
without distillation into an intermediate and heavy reformate.
Comparative Example 2
[0070] The total C.sub.5+ product produced in Example 1, without
distillation into an intermediate and heavy reformate, was
contacted with a ZSM-5 zeolite based catalyst described in Example
3 in a final reforming stage at 930.degree. F., 80 psig, 2:1 molar
ratio of hydrogen to hydrocarbon and 1.5 hr.sup.-1 LHSV feed rate.
The C.sub.5+ liquid yield was 89.9 wt. % and RON of the C.sub.5+
liquid product from the final reforming stage was 97.4. The
hydrogen production was 190 standard cubic feet per barrel feed. In
Table 5, the results from Example 4, where the final product was is
a blend from (i) the product produced in the final stage reforming
of the intermediate reformate in Example 3 and (ii) the heavy
reformate (Example 2) which was not subjected to the final stage
reforming, are compared to those obtained from Comparative Example
2, where the total C.sub.5+ product was produced from the total
C.sub.5+ penultimate effluent as feed, without distillation into an
intermediate and heavy reformate.
TABLE-US-00005 TABLE 5 Comparison of results from Example 4 and
Comparative Example 2 Example 4 Comparative Example 3 Example 2
Example 2 Feedstock Intermediate Heavy reformate Total C.sub.5+
reformate (Ex. 2, Table 3) penultimate effluent (Ex. 2, Table 3)
(Ex. 1, Table 2) Catalyst Pt/Na/Mg/ZSM-5 Not subjected to
Pt/Na/Mg/ZSM-5 with alumina the final stage with alumina binder
binder reforming Temperature, .degree. F. 900 -- 930 Pressure, psig
80 -- 80 LHSV, hr.sup.-1 1.5 -- 1.5 Molar H.sub.2/hydrocarbon 2:1
-- 2:1 Ratio RON of C.sub.5+ 97.0.sup.(1) 105.sup.(2) 97.4.sup.(3)
C.sub.5+ Yield, wt % 92.7.sup.(1) 100.sup.(2) 89.9.sup.(3) H.sub.2
Yield, scf/bbl feed 300.sup.(1) -- 190.sup.(3) Total RON of
C.sub.5+ 98.7.sup.(4) 97.4.sup.(3) Total C.sub.5+ Yield, wt %
94.2.sup.(4) 89.9.sup.(3) Total H.sub.2 Yield, scf/bbl feed
240.sup.(4) 190.sup.(3) Notes to Table 5: .sup.(1)For Example 3:
RON of C.sub.5+, C.sub.5+ yield and H.sub.2 production of the
product are given based on the intermediate reformate as feed.
.sup.(2)For Example 2: RON of C.sub.5+ and C.sub.5+ yield are given
based on the heavy reformate which is not subjected to the final
stage reforming. .sup.(3)For Comparative Example 2: RON of
C.sub.5+, C.sub.5+ yield and H.sub.2 production of the product are
given based on the total C.sub.5+ penultimate effluent as feed.
.sup.(4)For Example 4: Total RON of C.sub.5+, total C.sub.5+ yield
and total H.sub.2 production are given based on the total C.sub.5+
penultimate effluent as feed (which is distilled into intermediate
reformate and heavy reformate in Example 2). The final product of
Example 4 consists of a blend of (i) the product from the final
stage reforming of the intermediate reformate and (ii) the heavy
reformate which is not subjected to the final stage reforming.
[0071] Example 4 and Comparative Example 2 show the benefit of the
intermediate reformate as feed to the final reforming stage when
compared with using the full boiling range C.sub.5+ feed, with the
ZSM-5 zeolite based catalyst, in terms of C.sub.5+ yield, hydrogen
production and C.sub.5+ RON.
[0072] The RON values reported in Examples 3-4 and Comparative
Examples 1 and 2 above are calculated values, based on RON blending
correlations applied to a composition analysis using gas
chromatography. The method was calibrated to achieve a difference
between measured and calculated RON's of within .+-.0.8.
* * * * *