Chemistry of hydrocarbon compounds – Purification – separation – or recovery – By plural serial diverse separations
Reexamination Certificate
2001-03-08
2004-05-18
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Purification, separation, or recovery
By plural serial diverse separations
C585S810000, C208S347000, C208S350000, C203S017000
Reexamination Certificate
active
06737557
ABSTRACT:
BACKGROUND OF THE INVENTION
It is well known in the art that processes for thermal cracking of hydrocarbons such as ethane, propane, naphtha, and the like, produce a by-product referred to as pyrolysis gasoline or aromatic concentrate, which can be debutanized to form debutanized aromatic concentrate (DAC). This pyrolysis gasoline or DAC typically contains C
5
and heavier hydrocarbons, such as C
5
diolefins, C
5
olefins, aromatics, cyclopentadiene (CPD), and dicyclopentadiene (DCPD).
It is desirable to convert the CPD to DCPD which is a valuable industrial chemical which can be used in the production of elastomers and unsaturated polyester resins.
Typical pyrolysis gasoline upgrading processes separate the pyrolysis gasoline into a C
5
stream containing CPD and a C
6
+stream. The C
5
stream is then dimerized to form DCPD which is purified downstream. One problem with this process is that when the pyrolysis gasoline is obtained from storage, wherein a portion of the CPD is converted to DCPD, the separation of the pyrolysis gasoline into a C
5
stream and a C
6
+stream, and dimerization of CPD in the C
5
stream to DCPD, will result in splitting the DCPD between the C
5
stream and the C
6
+stream, necessitating the added expense of recovering DCPD from both the C
5
stream and the C
6
+stream.
Therefore, development of a process capable of efficiently upgrading a pyrolysis gasoline, obtained either directly from a hydrocarbon thermal cracking unit or from storage, would be a significant contribution to the art.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel process for upgrading a hydrocarbon feedstock comprising C
5
olefins, C
5
diolefins, CPD, DCPD and aromatics to produce a DCPD product and/or a C
5
diolefin product and/or a C
5
olefin product and/or an aromatic product.
It is yet another object of the present invention to provide a novel process of increased efficiency for recovering DCPD from pyrolysis gasoline.
It is still another object of the present invention to provide a novel process of increased efficiency for producing and recovering DCPD from pyrolysis gasoline containing a significant quantity of DCPD.
It is yet another object of the present invention to provide a novel process of increased efficiency for recovering DCPD from pyrolysis gasoline wherein the DCPD has a Pt/Co color number below about 30.
In accordance with a first embodiment of the present invention, a process for upgrading hydrocarbons is provided including the steps of:
a) heating a hydrocarbon feedstock comprising CPD, DCPD, C
5
diolefins, benzene, toluene, and xylene in a heating zone, to dimerize CPD to DCPD, thereby forming a first effluent;
b) separating the first effluent into a C
6
+stream and a C
5
diolefin stream comprising C
5
diolefins;
c) separating the C
6
+stream into a C
6
-C
9
stream and a C
6
+stream;
d) separating the C
10
+stream into a fuel oil stream and a DCPD stream comprising DCPD; and
e) hydrotreating the C
6
-C
9
stream to thereby form a BTX stream comprising benzene, toluene and xylene.
In accordance with a second embodiment of the present invention, a process for upgrading hydrocarbons is provided including the steps of:
a) heating a hydrocarbon feedstock comprising CPD, DCPD, C
5
diolefins, benzene, toluene, and xylene in a heating zone, to dimerize CPD to DCPD, thereby forming a first effluent;
b) separating the first effluent into a C
5
-C
9
stream and a C
10
+stream;
c) separating the C
10
+stream into a fuel oil stream and a DCPD stream comprising DCPD;
d) contacting the C
5
-C
9
stream with a selective hydrogenation catalyst, in a first reaction zone and in the presence of hydrogen, to hydrogenate at least a portion of the diolefins, alkynes, and styrene contained in the C
5
-C
9
stream, thereby forming a second effluent;
e) separating the second effluent into a C
6
-C
9
stream and a C
5
olefin stream comprising C
5
olefins;
f) contacting the C
6
-C
9
stream with a hydrodesulfurization catalyst, in a second reaction zone and in the presence of hydrogen, to desulfurize at least a portion of the sulfur-containing compounds contained in the C
6
-C
9
stream thereby forming a BTX stream comprising benzene, toluene and xylene.
In accordance with a third embodiment of the present invention, a process for recovering DCPD from a hydrocarbon feedstock is provided including the steps of:
a) providing a first separation column, a first overhead condenser, and a first reboiler, the first separation column defining a first separation zone having an upper portion, a lower portion and an intermediate portion, the intermediate portion of the first separation zone comprising at least about 50 theoretical trays;
b) providing a second separation column, a second overhead condenser, and a second reboiler, the second separtion column defining a second separation zone having an upper portion, a lower portion and an intermediate portion, the intermediate portion of the second separation zone comprising at least about 9 theoretical trays;
c) introducing a hydrocarbon feedstock comprising DCPD to the intermediate portion of the first separation zone;
d) allowing a first vaporous overhead stream comprising C
9
-hydrocarbons, and having a pressure in the range of from about 0.5 psia to about 3.0 psia and a temperature in the range of from about 160° F. to about 200° F., to pass from the upper portion of the first separation column to the first overhead condenser;
e) condensing at least a portion of the first vaporous overhead stream in the first overhead condenser thereby forming a first condensate having a temperature in the range of from about 50° F. to about 90° F.;
f) refluxing at least a portion of the first condensate from the first overhead condenser to the upper portion of the first separation zone;
g) allowing a first liquid bottoms stream comprising C
10
+hydrocarbons to pass from the lower portion of the first separation column to the first reboiler;
h) reboiling at least a portion of the first liquid bottoms stream in the first reboiler at a temperature in the range of from about 210° F. to about 250° F. thereby forming a first reboiled stream and a remaining portion of the first liquid bottoms stream;
i) introducing the first reboiled stream to the lower portion of the first separation zone;
j) introducing the remaining portion of the first liquid bottoms stream to the intermediate portion of the second separation zone;
k) allowing a second vaporous overhead stream comprising DCPD, and having a pressure in the range of from about 0.1 psia to about 2.0 psia and a temperature in the range of from about 160° F. to about 200° F., to pass from the upper portion of the second separation zone to the second overhead condenser;
l) condensing at least a portion of the second vaporous overhead stream in the second overhead condenser thereby forming a second condensate having a temperature in the range of from about 70° F. to about 100° F.;
m) refluxing at least a portion of the second condensate to the upper portion of the second separation zone and thereby forming a remaining portion of the second condensate;
n) allowing a second liquid bottoms stream comprising fuel oil to pass from the lower portion of the second separation zone to the second reboiler;
o) reboiling at least a portion of the second liquid bottoms stream in the second reboiler at a temperature in the range of from about 190° F. to about 240° F. thereby forming a second reboiled stream;
p) introducing the second reboiled stream to the lower portion of the second separation zone; and
q) recovering the remaining portion of the second condensate from the second overhead condenser thereby forming a DCPD stream.
Other objects and advantages will become apparent from the detailed description and the appended claims.
REFERENCES:
patent: 3492220 (1970-01-01), Lempert et al.
patent: 4450069 (1984-05-01), Kidwell et al.
patent: 5321177 (1994-06-01), Nakamura et al.
patent: 5401890 (1995-03-01), Parks
patent: 5510550
Cheung Tin-Tack Peter
Johnson Marvin M.
Lashier Mark E.
Owen Steven A.
Carroll Rodney B.
Dang Thuan D.
P.C. Conley Rose
Phillips Petroleum Company
Reed K. KaRan
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