U.S. patent application number 16/703529 was filed with the patent office on 2021-06-10 for integrated processes to produce gasoline blending components from light naphtha.
This patent application is currently assigned to SAUDI ARABIAN OIL COMPANY. The applicant listed for this patent is SAUDI ARABIAN OIL COMPANY. Invention is credited to Omer Refa Koseoglu.
Application Number | 20210171840 16/703529 |
Document ID | / |
Family ID | 1000005608805 |
Filed Date | 2021-06-10 |
United States Patent
Application |
20210171840 |
Kind Code |
A1 |
Koseoglu; Omer Refa |
June 10, 2021 |
INTEGRATED PROCESSES TO PRODUCE GASOLINE BLENDING COMPONENTS FROM
LIGHT NAPHTHA
Abstract
A process for the treatment of a light naphtha feedstock that
comprises normal paraffins and iso-paraffins may include separating
the feedstock into a first iso-paraffin stream and a normal
paraffin stream. The separating may be performed with 5 A molecular
sieves, a pressure of about 1-3 bars, and a temperature of
100-260.degree. C. A product stream may be provided by subjecting
the normal paraffin stream to at least one of steam cracking,
isomerizing, and aromatizing.
Inventors: |
Koseoglu; Omer Refa;
(Dhahran, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAUDI ARABIAN OIL COMPANY |
Dhahran |
|
SA |
|
|
Assignee: |
SAUDI ARABIAN OIL COMPANY
Dhahran
SA
|
Family ID: |
1000005608805 |
Appl. No.: |
16/703529 |
Filed: |
December 4, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 2300/1044 20130101;
C07C 2521/06 20130101; C07C 2529/70 20130101; C07C 5/22 20130101;
C10G 61/06 20130101; C10G 57/00 20130101; C10L 1/1691 20130101;
C07C 4/04 20130101; C10L 2270/023 20130101; C10G 2300/30 20130101;
C07C 7/13 20130101; C07C 2/76 20130101 |
International
Class: |
C10G 57/00 20060101
C10G057/00; C07C 4/04 20060101 C07C004/04; C07C 2/76 20060101
C07C002/76; C07C 7/13 20060101 C07C007/13; C07C 5/22 20060101
C07C005/22; C10L 1/16 20060101 C10L001/16; C10G 61/06 20060101
C10G061/06 |
Claims
1. A process for treatment of a light naphtha feedstock, the
process comprising: separating the light naphtha feedstock
consisting of normal paraffins and iso-paraffins having 5 and 6
carbon atoms into an iso-paraffin stream and a normal paraffin
stream consisting of 5 and 6 carbon atoms; aromatizing the normal
paraffin stream to produce an aromatic stream and a non-aromatic
stream; and steam cracking the non-aromatic stream to provide an
olefinic stream.
2. (canceled)
3. The process of claim 1, wherein the iso-paraffin stream is sent
to a gasoline pool.
4. The process of claim 1, wherein the separating is performed with
5 A molecular sieves.
5. The process of claim 1, wherein the separating is performed at a
pressure ranging from about 1-3 bar.
6. The process of claim 1, wherein the separating is performed at a
temperature ranging from 100-260.degree. C.
7. The process of claim 1, wherein the aromatizing is performed
with a MFI zeolite catalyst.
8. The process of claim 1, wherein the aromatizing is performed at
a temperature of 500-600.degree. C.
9. The process of claim 1, wherein the steam cracking is performed
at a temperature of 750-850.degree. C.
10. The process of claim 1, wherein the steam cracking is performed
with a steam-to-hydrocarbon ratio ranging from 0.5:1 to 0.7:1 by
weight.
11. A process for treatment of a light naphtha feedstock, the
process comprising: separating the feedstock consisting of normal
paraffins and iso-paraffins having 5 and 6 carbon atoms into a
first iso-paraffin stream and a normal paraffin stream consisting
of 5 and 6 carbon atoms with 5 A molecular sieves at a pressure of
about 1-3 bars and a temperature of 100-260.degree. C.; and at
least one of steam cracking, isomerizing, and aromatizing the
normal paraffin stream to produce a product stream.
12. (canceled)
13. The process of claim 11, wherein the first iso-paraffin stream
is sent to a gasoline pool.
14. The process of claim 11, wherein the process comprises the
steam cracking, and wherein the steam cracking is performed with a
steam-to-hydrocarbon ratio ranging from 0.5:1 to 0.7:1 by
weight.
15. The process of claim 11, wherein the process comprises the
steam cracking, and wherein the steam cracking is performed at a
temperature of 750-850.degree. C.
16. The process of claim 11, wherein the process comprises the
isomerizing, and wherein the isomerizing comprises mixing the
normal paraffin stream with an amount of hydrogen such that a molar
ratio of hydrogen to the normal paraffin stream is of the range
0.04:1 to 0.06:1.
17. The process of claim 11, wherein the process comprises the
isomerizing, and wherein the isomerizing is performed at a
temperature ranging from about 100 to 200.degree. C.
18. The process of claim 11, wherein the process comprises the
isomerizing, and wherein the isomerizing is performed with a
zirconia-containing catalyst.
19. The process of claim 11, wherein the process comprises the
isomerizing, and wherein the isomerizing is performed with a liquid
hourly space velocity ranging from 1.0 to 2.0 h.sup.-1.
20. The process of claim 11, wherein the process comprises the
aromatizing, and wherein the aromatizing is performed at a
temperature of 500-600.degree. C.
Description
BACKGROUND OF INVENTION
[0001] Light naphtha, which is generally defined as a C5-C6
hydrocarbon feedstock, originates from routine refinery processes.
Light naphtha is generally used as a feed for steam crackers for
light olefin production, and as a blending stock for gasoline
production. However, light naphtha is generally an undesirable
gasoline blending component because of its low octane number and
high vapor pressure. Thus, the transformation of light naphtha into
value-added gasoline blending components is an ongoing
challenge.
[0002] The transformation of light naphtha is rendered difficult by
the inert nature of carbon-carbon and carbon-hydrogen bonds, which
require elevated temperatures for processing, providing unfavorable
thermodynamics, low selectivity and yields, and high cost. As
refiners process lighter feeds, such as shale oil and condensates,
the generation of light naphtha is increasing. Targets include the
production of isoalkanes, olefins, and/or aromatics from light
naphtha. These components generally provide a higher octane number
and, thus, are more useful additives for gasoline compositions
[0003] To date, options for processing light naphtha have been
limited. Typical processes are depicted in FIGS. 1A-1B, which
directly subject a light naphtha feedstock 10 to either steam
cracking 110 (FIG. 1A) or isomerization 120 (FIG. 1B). The steam
cracking 110 generates a cracked product stream 12 that mainly
comprises C.sub.2-4 olefins and methane, with smaller quantities of
other products. The isomerization 120, in contrast, results in an
isomerized product stream 14 that consists essentially of
iso-paraffins (or "isomerate"), resulting in an increase in the
research octane number (RON).
SUMMARY
[0004] This summary is provided to introduce a selection of
concepts that are further described below in the detailed
description. This summary is not intended to identify key or
essential features of the claimed subject matter, nor is it
intended to be used as an aid in limiting the scope of the claimed
subject matter.
[0005] In one aspect, embodiments disclosed herein relate to
processes for treating a light naphtha feedstock that includes
normal paraffins and iso-paraffins having 5 or 6 carbon atoms. The
processes may include separating the feedstock into an iso-paraffin
stream and a normal paraffin stream. The normal paraffin stream may
be aromatized to produce an aromatic stream and a non-aromatic
stream, and the non-aromatic stream may be subjected to steam
cracking to provide an olefinic stream.
[0006] In a further aspect, embodiments disclosed herein relate to
processes for treating a light naphtha feedstock that includes
normal paraffins and iso-paraffins having 5 or 6 carbon atoms. The
processes may include separating the feedstock into an iso-paraffin
stream and a normal paraffin stream. The separation may be
performed with 5 A molecular sieves, a pressure of about 1-3 bars,
and a temperature of 100-260.degree. C. A product stream may be
provided by subjecting the normal paraffin stream to at least one
of steam cracking, isomerizing, and aromatizing.
[0007] Other aspects and advantages of the claimed subject matter
will be apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIGS. 1A-B are schematic illustrations that depict prior art
processes for processing light naphtha.
[0009] FIG. 2 is a schematic illustration depicting a process and
system of one or more embodiments of the present disclosure.
[0010] FIG. 3 is a schematic illustration depicting a process and
system of one or more embodiments of the present disclosure.
[0011] FIG. 4 is a schematic illustration depicting a process and
system of one or more embodiments of the present disclosure.
[0012] FIG. 5 is a schematic illustration depicting a process and
system of one or more embodiments of the present disclosure.
DETAILED DESCRIPTION
[0013] Embodiments in accordance with the present disclosure
generally relate to processes and systems for upgrading light
naphtha to value added products. Generally, embodiments in
accordance with the present disclosure involve an initial
separation step that isolates iso-paraffins from normal paraffins.
The normal paraffins may then be processed through one or more
processes selected from the group consisting of steam cracking,
isomerization, and aromatization.
[0014] Traditional processing of a naphtha feed stream may only use
a naphtha splitter, which segregates different fractions according
to boiling point ranges. However, as distinct hydrocarbon fractions
may have boiling points that overlap, this method is insufficient
for, for instance, separating iso-paraffins from normal paraffins.
Therefore, naphtha processing is typically performed on a mixture
of normal and iso-paraffins. However, the operation of a cracking
unit works most efficiently with normal hydrocarbons, and so the
presence of iso-paraffins decreases the efficiency of the cracking
process. Further, if the naphtha feedstock is isomerized, the
isomerization will also be less efficient as the light naphtha
feedstock will already comprise a significant isomerate
fraction.
[0015] For the purposes of the present disclosure, accompanying
components that are conventionally used in light naphtha
processing, such as air supplies, catalyst hoppers, gas handling
apparatus, spent catalyst discharge sub-systems, catalyst
replacement sub-systems, valves, temperature sensors, electronic
controllers and the like, are not shown or discussed herein for
sake of simplicity. One of ordinary skill in the art would
appreciate that such components may be included in the embodiments
disclosed herein.
[0016] FIG. 2 depicts a process and a system of one or more
embodiments of the present disclosure, the system comprising a
separation unit 200 and a cracking unit 210.
[0017] In one or more embodiments, a light naphtha feedstock 10 is
fed into a separation unit 200. The light naphtha feedstock 10 of
one or more embodiments may comprise a mixture of C5 and C6
hydrocarbons. In further embodiments, the light naphtha feedstock
10 may consist essentially of C5 and C6 hydrocarbons or consist of
C5 and C6 hydrocarbons. In certain embodiments the feedstock 10 may
have an initial boiling point of any of 10, 20, 30, 36, 40, 50, and
65.degree. C., and a final boiling point of any of 75, 78, 80, 85,
90, 95, 100, and 110.degree. C. In one or more embodiments, the
feedstock 10 in accordance with the present disclosure may be a
hydrocarbon fraction having a boiling point ranging from about 30
to 90.degree. C. In further embodiments, the feedstock 10 in
accordance with the present disclosure may be a hydrocarbon
fraction having a boiling point ranging from about 36 to 78.degree.
C.
[0018] The light naphtha feedstock 10 of one or more embodiments
may comprise at least a portion of iso-paraffins, saturated
hydrocarbons with a branched-chain structure, and normal paraffins,
saturated hydrocarbons with a straight-chain structure. In one or
more embodiments, the feedstock 10 in accordance may comprise
iso-paraffins in an amount ranging from about 30 to 70% by weight
(wt. %). In some embodiments, the feedstock may comprise the
iso-paraffins in an amount ranging from a lower limit of any of 30,
40, 45, and, 50 wt. % to an upper limit of any of 40, 45, 50, 55,
60, and 70 wt. %, where any lower limit can be used with any
mathematically-compatible upper limit. In one or more embodiments,
the feedstock 10 in accordance may comprise normal paraffins in an
amount ranging from about 30 to 70% by weight (wt. %). In some
embodiments, the feedstock may comprise the normal paraffins in an
amount ranging from a lower limit of any of 30, 40, 45, and, 50 wt.
% to an upper limit of any of 40, 45, 50, 55, 60, and 70 wt. %,
where any lower limit can be used with any
mathematically-compatible upper limit. In one or more embodiments,
the feedstock 10 may be sourced from one or more of crude oil, a
gas condensate, liquid coal, biofuels, and intermediary refinery
processes.
[0019] The feedstock 10 of one or more embodiments may have a
sulfur content of 10 parts per million by weight (ppmw) or less, 5
ppmw or less, 3 ppmw or less, 1 ppmw or less, 0.5 ppmw or less,
less than 0.3 ppmw, or 0.1 ppmw or less. In one or more
embodiments, the feedstock 10 may have a sulfur content of 100 ppmw
or more, 1000 ppmw or more, 5000 ppmw or more, or 10000 ppmw or
more.
[0020] The feedstock 10 of one or more embodiments may have a
nitrogen content of 10 ppmw or less, 5 ppmw or less, 3 ppmw or
less, 1 ppmw or less, 0.5 ppmw or less, less than 0.3 ppmw, or 0.1
ppmw or less.
[0021] In one or more embodiments the feedstock 10 is separated in
a separation unit 200. The separation of one or more embodiments
isolates the iso-paraffins of the feedstock from the normal
paraffins. The separation provides an iso-paraffin stream 20 and a
normal paraffin stream 21. In one or more embodiments, the
iso-paraffin stream 20 may consist essentially of or, in some
embodiments consist of, iso-paraffins. In one or more embodiments,
the normal paraffin stream 21 may consist essentially of or, in
some embodiments consist of, normal paraffins.
[0022] In one or more embodiments, a molecular sieve adsorption
process is used to separate normal paraffins from iso-paraffins. In
some embodiments, this separation method relies on the pore size of
the molecular sieve to selectively adsorb normal paraffins due to
the relatively smaller molecular diameter of normal paraffins
compared to iso-paraffins. As would be appreciated by those having
ordinary skill in the art, the adsorption step is followed by a
desorption step for net recovery of normal paraffins. These steps
may be performed cyclically or pseudocontinuously. In a
pseudocontinuous process, a portion of the molecular sieves are
cycled between the adsorption and desorption steps, while a
remaining portion of the sieves are maintained under the separation
conditions. One of ordinary skill in the art will appreciate, with
the benefit of this disclosure, that the selection of a molecular
sieve is dependent upon the identity, and relative sizes, of the
normal and iso-paraffins. In one or more embodiments disclosed
herein, the separation may comprise the use of a 5 A molecular
sieve adsorbent.
[0023] In some embodiments, the separation step may separate
straight chain C5 and/or C6 paraffins from branched C5 and/or C6
paraffins. In additional embodiments, not shown in FIG. 2, straight
chain paraffins and singly branched C6 paraffins in the isomerate
reaction mixture may be separated from C6 paraffins having two or
more branches.
[0024] In one or more embodiments, the separation in accordance
with the present disclosure may be performed at a pressure ranging
from about 0.5 to 4 bar. In some embodiments, the separation may be
performed at a pressure ranging from a lower limit of any of 0.5,
0.8, 1.0, 1.2, 1.5, and 1.8 bar to an upper limit of any of 2.2,
2.5, 2.8, 3.0, 3.5, and 4.0 bar, where any lower limit can be used
with any mathematically-compatible upper limit. In particular
embodiments, the separation in accordance with the present
disclosure may be performed at a pressure ranging from about 1 to 3
bar.
[0025] In one or more embodiments, the separation 200 in accordance
with the present disclosure may be performed at a temperature
ranging from about 20 to 280.degree. C. In some embodiments, the
separation may be performed at a temperature ranging from a lower
limit of any of 20, 50, 95, 100, 120, 140, 160, and 180.degree. C.
to an upper limit of any of 180, 200, 220, 240, 260, and
280.degree. C., where any lower limit can be used with any
mathematically-compatible upper limit. In particular embodiments,
the separation in accordance with the present disclosure may be
performed at a temperature ranging from about 100 to 260.degree.
C.
[0026] In one or more embodiments, after separation 200, the normal
paraffin stream 21 may be fed to a steam cracking unit 210. Steam
cracking is a petrochemical process in which saturated
hydrocarbons, such as normal paraffins, are broken down into
smaller, often unsaturated, hydrocarbons. The steam cracking
process 210 detailed herein may produce various products, including
lighter alkenes (olefins) such as ethylene, propylene, and
butadiene, as well as methane and aromatics such as benzene and
toluene.
[0027] In one or more embodiments, the normal paraffin stream 21
may be diluted with steam (not shown on FIG. 2) and then heated in
an anaerobic furnace. After the cracking temperature has been
reached, the gas is quickly quenched to stop the reaction in a
transfer line exchanger. The products generated in the reaction,
and their yield, generally depend on the composition of the feed,
on the hydrocarbon to steam ratio and on the cracking temperature
(which may be very high), and furnace residence time (which may be
very short). Generally, higher cracking temperatures favor the
production of ethylene and benzene, whereas lower temperatures
produce relatively higher amounts of propene, C4-hydrocarbons, and
liquid products.
[0028] In one or more embodiments, the steam cracking in accordance
with the present disclosure may be performed at a temperature
ranging from about 600 to 1000.degree. C. In some embodiments, the
steam cracking may be performed at a temperature ranging from a
lower limit of any of 600, 700, 750, 775, 800, 825, and 850.degree.
C. to an upper limit of any of 850, 875, 900, 950, and 1000.degree.
C., where any lower limit can be used with any
mathematically-compatible upper limit. In particular embodiments,
the steam cracking in accordance with the present disclosure may be
performed at a temperature ranging from about 700 to 900.degree. C.
In particular embodiments, the steam cracking in accordance with
the present disclosure may be performed at a temperature of
approximately 800.degree. C.
[0029] In one or more embodiments, the steam cracking in accordance
with the present disclosure may be performed at a pressure ranging
from about 0.8 to 1.5 bar. In some embodiments, the steam cracking
may be performed at a pressure ranging from a lower limit of any of
0.8, 0.9, 1.0, 1.1, and 1.2 bar to an upper limit of any of 1.0,
1.1, 1.2, 1.3, 1.4, and 1.5 bar, where any lower limit can be used
with any mathematically-compatible upper limit. In particular
embodiments, the steam cracking in accordance with the present
disclosure may be performed at a pressure ranging of approximately
1 bar.
[0030] In one or more embodiments, the steam cracking in accordance
with the present disclosure may be performed at a steam to
hydrocarbon ratio ranging from about 0.1:1 to 0.8:1 by weight. In
some embodiments, the steam cracking may be performed at a steam to
hydrocarbon ratio ranging from a lower limit of any of 0.1:1,
0.2:1, 0.3:1, 0.4:1, 0.5:1, and 0.6:1, by weight, to an upper limit
of any of 0.5:1, 0.6:1, 0.7:1, and 0.8:1, by weight, where any
lower limit can be used with any mathematically-compatible upper
limit. In particular embodiments, the steam cracking in accordance
with the present disclosure may be performed at a steam to
hydrocarbon ratio of approximately 0.6:1 by weight.
[0031] In one or more embodiments, the steam cracking in accordance
with the present disclosure may be performed with a residence time
of less than 1 second. In some embodiments, the steam cracking may
be performed with a residence time ranging from a lower limit of
any of 0.01, 0.10, 0.20, 0.30, 0.35, and 0.40 seconds to an upper
limit of any of 0.40, 0.50, 0.60, 0.75, and 1.0 seconds, where any
lower limit can be used with any mathematically-compatible upper
limit. In particular embodiments, the steam cracking in accordance
with the present disclosure may be performed with a residence time
of approximately 0.35 seconds.
[0032] The steam cracking 210 of one or more embodiments may
produce a steam-cracked product stream 22. The product stream 22
may comprise a portion of light (C.sub.2-4) olefins. In some
embodiments, the product stream may comprise light olefins in an
amount of 30 wt. % or more, 40 wt. % or more, or 50 wt. % or more.
In some embodiments, the product stream may comprise light olefins
in an amount ranging from about 40 to 60 wt. % or, in particular
embodiments, about 45 to 55 wt. %. In one or more embodiments, the
product stream 22 may comprise an aromatic portion that may include
one or more of benzene, toluene, and xylenes. In some embodiments,
the product stream may comprise an aromatic portion in an amount of
20 wt. % or less. In some embodiments, the product stream 22 may
comprise the aromatic portion in an amount ranging from about 5 to
15 wt. %. The cracked product stream may be treated, recovered and
further processed by any method, and for any use, known to one of
ordinary skill in the art.
[0033] The iso-paraffin stream 20 may be treated, recovered and
further processed by any method, and for any use, known to one of
ordinary skill in the art. In some embodiments, finished gasoline
may be produced by blending at least a portion of the iso-paraffin
stream with other gasoline components, such as one or more of
butanes, butenes, pentanes, naphtha, catalytic reformate,
isomerate, alkylate, polymer, aromatic extract, heavy aromatics,
gasoline from catalytic cracking, hydrocracking, thermal cracking,
thermal reforming, steam pyrolysis and coking, oxygenates such as
methanol, ethanol, propanol, isopropanol, tert-butyl alcohol,
sec-butyl alcohol, methyl tertiary butyl ether, ethyl tertiary
butyl ether, methyl tertiary amyl ether and higher alcohols and
ethers, and small amounts of additives to provide a desired
property.
[0034] FIG. 3 depicts a process and a system of one or more
embodiments of the present disclosure, the system comprising a
separation unit 200 and an isomerization unit 220. It is noted that
component 200 and feeds 10, 20, and 21 are the same as discussed
above with regard to FIG. 2 and, though their description is not
repeated, each stream, component, and condition described above is
also present in the embodiment shown in FIG. 3
[0035] Generally, the processes represented by FIG. 3 differ from
those represented by FIG. 2, discussed above, in that the normal
paraffin stream 21 is fed to an isomerization unit 220 where it is
isomerized, rather than the steam cracking unit 210 of FIG. 2.
[0036] In one or more embodiments, an isomerization in accordance
with the present disclosure will increase the RON of the
hydrocarbon mixture, and comprises mixing the normal paraffin
stream 21 with an excess of hydrogen gas (not shown in FIG. 3) to
dissolve a portion of the hydrogen gas in the liquid hydrocarbon
feedstock to produce a hydrogen-enriched liquid hydrocarbon
feedstock and reacting the normal paraffins to produce isomerates.
The normal paraffin stream 21 of one or more embodiments may have a
RON of 60 or less, of 50 or less, or of 45 or less.
[0037] The isomerization unit may have any suitable configuration
known to one of ordinary skill in the art. In some embodiments, the
unit can include one or more fixed-bed, moving-bed, fluidized-bed,
or batch reactor systems. The isomerization reaction zone may
include a single reactor or multiple reactor configurations with
suitable fluid communication between reactors and thermal means and
control to ensure that the desired isomerization temperature is
maintained at the inlet to each zone.
[0038] In one or more embodiments, the isomerization may use any
suitable catalyst known to a person of ordinary skill in the art.
The isomerization catalysts of one or more embodiments may include,
but are not limited to, those that are amorphous, for example
comprising amorphous alumina, or zeolitic, such as platinum on
alumina, a zeolite, a chlorinated alumina, a sulfated zirconia and
platinum, a platinum group metal on chlorided alumina, a tungstated
support of a Group IVB oxide or hydroxide. In one or more
embodiments the catalyst may comprise 0.05 wt. % to 5 wt. % of a
Group VIIIB metal. In some embodiments, the catalyst may comprise a
base material, such as zeolite or alumina, and one or more Group
IIIB or IVB metal oxides. In particular embodiments, the catalyst
may be a zirconia-based catalyst. As used herein, the term
"zeolite" includes not only aluminosilicates but variants in which
the aluminum is replaced by other trivalent elements and/or silicon
is replaced by other tetravalent elements.
[0039] In one or more embodiments, the isomerization in accordance
with the present disclosure may be performed at a pressure ranging
from about 10 to 100 bar. In some embodiments, the isomerization
may be performed at a pressure ranging from a lower limit of any of
10, 20, 30, 35, 40, and 50 bar to an upper limit of any of 45, 50,
60, 70, 80, 90, and 100 bar, where any lower limit can be used with
any mathematically-compatible upper limit. In particular
embodiments, the isomerization in accordance with the present
disclosure may be performed at a pressure of approximately 40
bar.
[0040] In one or more embodiments, the isomerization in accordance
with the present disclosure may be performed at a hydrogen to
hydrocarbon mole ratio (H.sub.2:HC) ranging from about 0.01:1 to
20:1. In some embodiments, the isomerization may be performed at a
H.sub.2:HC ranging from a lower limit of any of 0.01:1, 0.02:1,
0.03:1, 0.04:1, 0.05:1, and 0.10:1, to an upper limit of any of
0.06:1, 0.08:1, 0.10:1, 0.20:1, 0.50:1, 1:1, 5:1, 10:1, and 20:1,
where any lower limit can be used with any
mathematically-compatible upper limit. In particular embodiments,
the steam cracking in accordance with the present disclosure may be
performed at a H.sub.2:HC of approximately 0.05:1.
[0041] In one or more embodiments, the isomerization may be
performed with a liquid hourly space velocity (LHSV) ranging from a
lower limit of any of 0.2, 0.5, 1.0, and 1.5 h.sup.-1 to an upper
limit of any of 1.5, 2.0, 5.0, and 20 h.sup.-1, where any lower
limit can be used with any mathematically-compatible upper limit.
In particular embodiments, the isomerization in accordance with the
present disclosure may be performed with a LHSV of approximately
1.5 h.sup.-1.
[0042] In one or more embodiments, the isomerization in accordance
with the present disclosure may be performed at a temperature
ranging from about 20 to 300.degree. C. In some embodiments, the
isomerization may be performed at a temperature ranging from a
lower limit of any of 20, 50, 80, 100, 120, 140, 160, and
180.degree. C. to an upper limit of any of 180, 200, 220, 240, 260,
and 300.degree. C., where any lower limit can be used with any
mathematically-compatible upper limit. In particular embodiments,
the isomerization in accordance with the present disclosure may be
performed at a temperature of approximately 160.degree. C. In some
embodiments, lower reaction temperatures may be preferred to favor
equilibrium mixtures having the highest concentration of
high-octane highly branched iso-paraffins and to minimize cracking
of the feed to lighter hydrocarbons. One of ordinary skill in the
art would appreciate, with the benefit of this disclosure, that the
temperature and other conditions are also partially determined by
the type of catalyst used.
[0043] In some embodiments, the isomerization conditions in the
isomerization may be maintained at levels effective to maintain at
least about 90% by volume of the normal paraffin stream 21 in
liquid phase. In particular embodiments, the isomerization is
performed under conditions effective to increase the RON of the
normal paraffin stream 21. In some embodiments, the resulting
iso-paraffin stream 24 may have a RON of 75 or more, of 80 or more,
of 85 or more, or of 90 or more. The iso-paraffin stream 24 of one
or more embodiments may comprise a significant isomerate portion.
In some embodiments, the resulting iso-paraffin stream 24 may
comprise isomerates in an amount of 80 wt. % or more, 90 wt. % or
more, 95 wt. % or more, or 99 wt. % or more. In some embodiments,
the iso-paraffin stream may consist essentially of, or in other
embodiments consist of, isomerates.
[0044] The iso-paraffin stream 24 may be treated, recovered and
further processed by any method, and for any use, known to one of
ordinary skill in the art. The stream 24 may be treated the same
as, or different from, stream 20. In one or more embodiments, the
stream 24 may be combined 25 with the iso-paraffin stream 20. In
some embodiments, finished gasoline may be produced by blending at
least a portion of the iso-paraffin stream 24 with other gasoline
components, such as one or more of butanes, butenes, pentanes,
naphtha, catalytic reformate, isomerate, alkylate, polymer,
aromatic extract, heavy aromatics, gasoline from catalytic
cracking, hydrocracking, thermal cracking, thermal reforming, steam
pyrolysis and coking, oxygenates such as methanol, ethanol,
propanol, isopropanol, tert-butyl alcohol, sec-butyl alcohol,
methyl tertiary butyl ether, ethyl tertiary butyl ether, methyl
tertiary amyl ether and higher alcohols and ethers, and small
amounts of additives to provide a desired property.
[0045] FIG. 4 depicts a process and a system of one or more
embodiments of the present disclosure, the system comprising a
separation unit 200 and an aromatization unit 230. It is noted that
component 200 and feeds 10, 20, and 21 are the same as discussed
above with regard to FIGS. 2 and 3 and, though their description is
not repeated, each stream, component, and condition described above
is also present in the embodiment shown in FIG. 4.
[0046] Generally, the processes represented by FIG. 4 differ from
those represented by FIGS. 2 and 3, discussed above, in that the
normal paraffin stream 21 is fed to an aromatization unit 230 where
it is aromatized, rather than the steam cracking unit 210 of FIG. 2
or the isomerization unit 220 of FIG. 3.
[0047] In one or more embodiments, the aromatization of the present
disclosure may be any such process known to one of ordinary skill
in the art that is suitable for converting normal paraffins into a
product stream rich in one or more of benzene, toluene and xylenes,
and light hydrocarbon gases. Benzene and xylenes are useful
petrochemical building blocks for many chemical and polymer
materials. In one or more embodiments, the aromatization 230
generates an aromatic-rich stream 26.
[0048] In one or more embodiments, the aromatization in accordance
with the present disclosure may be performed at a pressure ranging
from about 0.5 to 80 bar. In some embodiments, the aromatization
may be performed at a pressure ranging from a lower limit of any of
0.5, 0.8, 1.0, 1.5, 5, 10, and 20 bar to an upper limit of any of
1.2, 1.5, 2, 5, 10, 25, 50, and 80 bar, where any lower limit can
be used with any mathematically-compatible upper limit. In
particular embodiments, the aromatization in accordance with the
present disclosure may be performed at a pressure of approximately
1 bar.
[0049] In one or more embodiments, the aromatization may be
performed with a liquid hourly space velocity (LHSV) ranging from a
lower limit of any of 0.2, 0.5, 1.0, and 1.5 h.sup.-1 to an upper
limit of any of 1.5, 2.0, 5.0, and 20 h.sup.-1, where any lower
limit can be used with any mathematically-compatible upper limit.
In particular embodiments, the aromatization in accordance with the
present disclosure may be performed with a LHSV of approximately 1
h.sup.-1.
[0050] In one or more embodiments, the aromatization may be
performed with any suitable aromatization catalyst known to one of
ordinary skill in the art. In some embodiments, the catalyst may be
a zeolite. In particular embodiments a MFI type zeolite catalyst
may be used. The catalyst of one or more embodiments may be used in
either a moving bed or a fixed bed.
[0051] In one or more embodiments, the aromatization in accordance
with the present disclosure may be performed at a temperature
ranging from about 200 to 700.degree. C. bar. In some embodiments,
the aromatization may be performed at a temperature ranging from a
lower limit of any of 200, 300, 400, 500, and 550 C to an upper
limit of any of 500, 550, 600, and 700.degree. C., where any lower
limit can be used with any mathematically-compatible upper limit.
In particular embodiments, the aromatization in accordance with the
present disclosure may be performed at a temperature of
approximately 550.degree. C.
[0052] The aromatization of one or more embodiments may generate an
aromatic-rich stream 26, which comprises a portion of one or more
of benzene, toluene, xylenes. In some embodiments, the
aromatic-rich stream 26 may comprise benzene in an amount ranging
from about 5 to 10 wt. %. In some embodiments, the aromatic-rich
stream 26 may comprise xylenes in an amount ranging from about 5 to
10 wt. %. In some embodiments, the aromatic-rich stream 26 may
comprise no substantial quantity of toluene. In one or more
embodiments, the aromatic-rich stream 26 comprises an aromatics
content of 10 wt. % or more, 15 wt. % or more, 20 wt. % or more, or
25 wt. % or more. In some embodiments, the aromatic-rich stream 26
comprises an aromatics content of 80 wt. % less, 60 wt. % or less,
40 wt. % or more, or 20 wt. % or less. In one or more embodiments,
the aromatic-rich stream 26 is passed downstream for additional
processing and separations, including petrochemical processing. The
aromatics-rich steam 26 of one or more embodiments may comprise an
unreacted portion of the normal paraffins of stream 21. The
unreacted paraffins may constitute the aromatics-rich steam 26 in
an amount of 30 wt. % or less, 20 wt. % or less, or 10 wt. % or
less. The aromatics-rich steam 26 of one or more embodiments may
further comprise a portion of light (C.sub.2-4) olefins and, in
some embodiments, be combined 27 with the iso-paraffin stream
20.
[0053] FIG. 5 depicts a process and a system of one or more
embodiments of the present disclosure, the system comprising a
separation unit 200, an aromatization unit 230, and a cracking unit
310. It is noted that components 200 and 230, and feeds 10, 20, and
21 are the same as discussed above with regard to FIGS. 2-4 and,
though their description is not repeated, each stream, component,
and condition described above is also present in the embodiment
shown in FIG. 3.
[0054] Generally, the processes represented by FIG. 5 differ from
those represented by
[0055] FIG. 4, discussed above, in that the aromatization unit 230
provides two streams: an aromatic stream 36 and a non-aromatic
stream 39, which is subsequently subjected to steam cracking 310,
rather than the aromatization of FIG. 4 that provides only one
aromatic-rich stream.
[0056] In one or more embodiments, the aromatization 230 of the
normal paraffin stream 21 produces a variety of hydrocarbon
components. Such components comprise one or more aromatics,
including one or more of the group consisting of benzene, toluene
and xylene. The aromatization of some embodiments further provides
one or more of an unreacted portion of the normal paraffins of
stream 21, an isomerate portion, and a portion of light (C.sub.2-4)
olefins. In some embodiments, the aromatics may be separated and
removed from the aromatization unit 230 as an aromatic stream 36.
The aromatics may be separated from the other components by any
method known to the art, including fractionation. The remaining
products of aromatization are sent as a non-aromatic stream 39 to a
steam cracking unit 310.
[0057] The aromatic stream 36 of one or more embodiments may
consist essentially of one or more of benzene, toluene, and
xylenes. In some embodiments, the aromatic stream 36 may consist of
a mixture of one or more of benzene, toluene, and xylenes. In some
embodiments, the aromatic stream 36 comprises benzene in an amount
ranging from 40 to 60 wt. %. In some embodiments, the aromatic
stream 36 comprises xylenes in an amount ranging from 40 to 60 wt.
%.
[0058] The non-aromatic stream 39 may comprise an unreacted portion
of the normal paraffins of stream 21. The non-aromatic stream may
comprise unreacted paraffins in an amount of 30 wt. % or less, 20
wt. % or less, or 10 wt. % or less. The non-aromatic stream 39 may
comprise an isomerate portion, which in some embodiments may
constitute the non-aromatic stream 39 in an amount of 30 wt. % or
less, 20 wt. % or less, or 10 wt. % or less. The non-aromatic
stream 39 of one or more embodiments may further comprise a portion
of light (C.sub.2-4) olefins.
[0059] In one or more embodiments, the non-aromatic stream 39 may
be steam cracked. The steam-cracking 310 may be performed in
accordance with any of the conditions and configurations discussed
previously regarding the steam cracking 210 of FIG. 2. The steam
cracking generates an olefinic stream 32. The olefinic stream 39
may comprise a significant portion of ethylene in addition to other
light olefins and aromatics. The olefinic stream 39 may be treated
by any method known by one of ordinary skill in the art, and passed
downstream for additional processing and separations, including
petrochemical processing.
EXAMPLES
[0060] The following examples are merely illustrative and should
not be interpreted as limiting the scope of the present
disclosure.
[0061] To illustrate the effect of separation on the product
composition provided by some of the aforementioned embodiments,
Comparative Examples 1 and 2 and Examples 1-4 are given below.
Reported in Tables 1-6 are the material balances (by mass) for each
Example, as obtained by simulations (Examples 1 and 4 and Comp. Ex
1-2) and experiments (Examples 2-3).
[0062] Example 1 was prepared by a process in accordance with one
or more embodiments represented by FIG. 2, involving a paraffin
separation step and subsequent steam cracking of a normal paraffin
stream. The separation was performed at a pressure of 1-3 bars,
with a proprietary molsieve 5 A adsorbent, and at a temperature of
100-260.degree. C. The steam cracking was performed at a
temperature of 800.degree. C., a pressure of 1 bar, a
steam-to-hydrocarbon weight ratio of 0.6:1, and a residence time of
0.35 seconds.
TABLE-US-00001 TABLE 1 Material Balance for Example 1 (streams
labelled as per FIG. 2) Stream# 10 21 20 22 Light Naphtha 80,000
Isomerate 38,640 Paraffins 41,360 Hydrogen 620 Methane 7,114 Ethane
Ethylene 13,897 Propane Propylene 6,452 Butadiene 1,861 Other C4
1,737 Benzene 2,771 Toluene 1,406 Xylenes Pyrolysis 3,557 Gasoline
Fuel oil 1,944 Total 80,000 41,360 38,640 41,360 RON 62.3 43.1 82.8
NA
[0063] Example 2 was prepared by a process in accordance with one
or more embodiments represented by FIG. 3, involving a paraffin
separation step and subsequent isomerization of a normal paraffin
stream. The separation was performed as for Example 1. The
isomerization was performed at a temperature of 160.degree. C., an
outlet pressure of 40 bar, a H.sub.2:hydrocarbon mole ratio of
0.05:1, a LHSV of 1.5 h.sup.-1, and with a zirconia commercial
catalyst.
TABLE-US-00002 TABLE 2 Material Balance for Example 2 (streams
labelled as per FIG. 3) Stream# 10 21 20 24 25 Light Naphtha 80,000
Isomerate 38,640 40,946 79,586 Paraffins 41,360 -- Hydrogen --
Methane -- Ethane Ethylene -- Propane Propylene -- Butadiene --
Other C4 -- Benzene -- Toluene -- Xylenes Pyrolysis -- Gasoline
Fuel oil -- Total 80,000 41,360 38,640 -- 79,586 RON 62.3 43.1 82.8
NA 82.8
[0064] Example 3 was prepared by a process in accordance with one
or more embodiments represented by FIG. 4, involving a paraffin
separation step and subsequent aromatization of a normal paraffin
stream. The separation was performed as for Example 1. The
aromatization was performed at a temperature of 550.degree. C., an
outlet pressure of 1 bar, a LHSV of 1 h.sup.-1, and with a MFI-type
zeolite catalyst.
TABLE-US-00003 TABLE 3 Material Balance for Example 3 (streams
labelled as per FIG. 4) Stream# 10 21 20 26 27 Light Naphtha 80,000
Isomerate 38,640 7,607 46,247 Paraffins 41,360 8,577 8,577 Hydrogen
-- Methane 1,386 1,386 Ethane 3,344 3,344 Ethylene 2,179 2,179
Propane 5,923 5,923 Propylene 2,447 2,447 Butadiene -- Other C4
3,771 3,771 Benzene 3,082 3,082 Toluene -- Xylenes 3,044 3,044
Pyrolysis -- Gasoline Fuel oil -- Total 80,000 41,360 38,640 41,360
80,000 RON 62.3 43.1 82.8 NA 82.8
[0065] Example 4 was prepared by a process in accordance with one
or more embodiments represented by FIG. 5, involving a paraffin
separation step and subsequent aromatization of a normal paraffin
stream. The aromatization gives a non-aromatic stream that is then
steam cracked. The separation, aromatization, and steam cracking
were performed as for Examples 1-3.
TABLE-US-00004 TABLE 4 Material Balance for Example 4 (streams
labelled as per FIG. 5) Stream# 10 21 20 39 36 32 Light Naphtha
80,000 Isomerate 38,640 7,607 Paraffins 41,360 8,577 Hydrogen 768.0
Methane 1,386 7311.6 Ethane 3,344 0.0 Ethylene 2,179 12896.3
Propane 5,923 0.0 Propylene 2,447 4637.9 Butadiene 1176.8 Other C4
3,771 1182.9 Benzene 3,082 1440.2 Toluene 630.6 Xylenes 3,044 291.3
Pyrolysis Gasoline 1508.9 Fuel oil 760.6 Total 80,000 41,360 38,640
35,233 6,127 32,605 RON 62.3 43.1 82.8 82.8 NA NA
[0066] Comparative Example 1 was prepared by a process in
accordance with one or more embodiments represented by FIG. 1A,
involving steam cracking a light naphtha feed. The steam cracking
was performed as for Example 1.
TABLE-US-00005 TABLE 5 Material Balance for Comp. Example 1
(streams labelled as per FIG. 1A) Stream# 10 12 Light Naphtha
80,000 Isomerate Paraffins Hydrogen 1,200 Methane 13,760 Ethane --
Ethane 26,880 Propane -- Propylene 12,480 Butadiene 3,600 Other C4
3,360 Benzene 5,360 Toluene 2,720 Xylenes Pyrolysis Gasoline 6,880
Fuel oil 3,760 Total 80,000 80,000 RON 62.28 NA
[0067] Comparative Example 2 was prepared by a process in
accordance with one or more embodiments represented by FIG. 1B,
involving isomerizing a light naphtha feed. The isomerization was
performed as for Example 2.
TABLE-US-00006 TABLE 6 Material Balance for Comp. Example 2
(streams labelled as per FIG. 1B) Stream# 10 14 Light Naphtha
80,000 Isomerate 79,897 Paraffins Hydrogen Methane Ethane Ethylene
Propane Propylene Butadiene Other C4 Benzene Toluene Xylenes
Pyrolysis Gasoline Fuel oil Total 80,000 79,897 RON 62.3 82.0
[0068] Although the preceding description has been described herein
with reference to particular means, materials and embodiments, it
is not intended to be limited to the particulars disclosed herein;
rather, it extends to all functionally equivalent structures,
methods and uses, such as are within the scope of the appended
claims. In the claims, means-plus-function clauses are intended to
cover the structures described herein as performing the recited
function and not only structural equivalents, but also equivalent
structures. Thus, although a nail and a screw may not be structural
equivalents in that a nail employs a cylindrical surface to secure
wooden parts together, whereas a screw employs a helical surface,
in the environment of fastening wooden parts, a nail and a screw
may be equivalent structures. It is the express intention of the
applicant not to invoke 35 U.S.C. .sctn. 112(f) for any limitations
of any of the claims herein, except for those in which the claim
expressly uses the words `means for` together with an associated
function.
* * * * *