Chemistry of hydrocarbon compounds – Plural serial diverse syntheses – To produce alicyclic
Reexamination Certificate
1999-09-30
2001-07-10
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Plural serial diverse syntheses
To produce alicyclic
C585S319000, C585S329000, C585S362000, C208S049000, C208S211000
Reexamination Certificate
active
06258989
ABSTRACT:
The present invention relates to the field of hydrocarbon upgrading processes. More specifically, the present invention relates to the upgrading of a pyrolysis gasoline, obtained from a hydrocarbon thermal cracking process, to products such as C
5
diolefins, C
5
olefins, dicyclopentadiene, and aromatics such as benzene, toluene and xylene (BTX).
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
10
+ 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 tempeature 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 se
Cheung Tin-Tack Peter
Johnson Marvin M.
Lashier Mark E.
Owen Steven A.
Anderson Jeffrey R.
Dang Thuan D.
Griffin Walter D.
Phillips Petroleum Company
Stewart Charles W.
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