1
DESCRIPTION
METHOD FOR PRODUCING MONOCYCLIC AROMATIC HYDROCARBONS
TECHNICAL FIELD
[OOOl]
The present invention relates to a method for producing monocyclic aromatic
hydrocarbons in which monocyclic aromatic hydrocarbons are produced from polycyclic
aromatic hydrocarbons.
10 Priority is claimed on Japanese Patent Application No. 201 1-1 15639, filed May
24,20 1 1, and Japanese Patent Application No. 20 1 1 - 1 1564 1, filed May 24,20 1 1, the
content of which is incorporated herein by reference.
BACKGROUND ART
15 [0002]
Light cycle oil (hereinafter referred to as "LCO"), which is cracked light oil
produced using a fluid catalytic cracking unit, contains a large amount of polycyclic
aromatic hydrocarbon and has been used as diesel or fuel oil. However, in recent years,
there has been a proposal to obtain high-value-added monocyclic aromatic hydrocarbons
20 (for example, benzene, toluene, xylene, ethyl benzene and the like) which can be used as
a high-octane gasoline base material or a petrochemical raw material from LC0 (for
example, refer to Patent documents 1 to 4).
Prior art documents
25 Patent documents
2
[0003]
[Patent document 11 Japanese Unexarnined Patent Application, First
Publication No. H3-2 128
[Patent document 21 Japanese Unexamined Patent Application, First
5 Publication No. H3-52993
[Patent document 31 Japanese Unexamined Patent Application, First
Publication No. H3-2679 1
[Patent document 41 Pamphlet of PCT International Publication No.
W0201Ol109899
10
DISCLOSURE OF INVENTION
Technical Problem
However, methods disclosed in Patent documents 1 to 4 do not exhibit a
15 sufficiently high yield of monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms
all the time. That is, in the above methods, a number of relatively-low-value-added
byproducts other than the target monocyclic aromatic hydrocarbons having 6 to 8 carbon
atoms are produced.
[0005]
20 The invention has been made to solve the above problem, and an object of the
invention is to provide a method for producing monocyclic aromatic hydrocarbons which
can produce monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms at a high
yield from a feedstock oil containing a polycyclic aromatic hydrocarbon.
25 Solution to Problem
[0006]
The present inventors repeated comprehensive studies to achieve the above
object and, consequently, obtained the following finding.
In order to increase the yield of monocyclic aromatic hydrocarbons having 6 to 8
5 carbon atoms, it is effective to circulate heavy fractions other than target products
(monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms) in reaction products to a
cracking and reforming reaction step so as to make the heavy fractions mixed with a
feedstock oil and undergo a cracking and reforming reaction again. Here, the cracking
and reforming reaction refers to a reaction in which monocyclic aromatic hydrocarbons
10 are produced through cracking and reforming using a fluidized bed.
As a result of additional studies based on the above finding, the inventors found
that the yield of target products can be further increased by adjusting fractions being
circulated, and completed the invention.
[0007]
First aspect:
[I] A method for producing monocyclic aromatic hydrocarbons according to a
first aspect of the invention is a method for producing monocyclic aromatic hydrocarbons
in which monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms are produced
from a feedstock oil having a 10 volume percent distillation temperature of 140°C or
20 higher and a 90 volume percent distillation temperature of 380°C or lower, includes:
a cracking and reforming reaction step of obtaining products containing
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms and a heavy fraction
having 9 or more carbon atoms by bringing the feedstock oil into contact with a catalyst
for producing monocyclic aromatic hydrocarbons containing crystalline aluminosilicate
25 to cause a reaction,
4
a catalyst separation step of separating and removing the catalyst for producing
monocyclic aromatic hydrocarbons together with tricyclic aromatic hydrocarbons
contained in the products from a mixture of the products and a small amount of the
catalyst for producing monocyclic aromatic hydrocarbons carried by the products, both
of which are derived in the cracking and reforming reaction step, and
a purification and recovery step of purifying and recovering the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated from the products
formed in the cracking and reforming reaction step.
[2] The method for producing monocyclic aromatic hydrocarbons according to
[I], in which, in the catalyst separation step, a heavy fraction separated using a separation
step of separating the products formed in the cracking and reforming reaction step into a
plurality of fractions is brought into contact with the mixture of the products and the
catalyst for producing monocyclic aromatic hydrocarbons carried by the products, both
of which are derived in the cracking and reforming reaction step, thereby removing the
catalyst for producing monocyclic aromatic hydrocarbons from the mixture.
[3] The method for producing monocyclic aromatic hydrocarbons according to
[I] or [2], in which the heavy fraction separated using the separation step contains
tricyclic aromatic hydrocarbons as a main component.
[OOOS]
Second aspect:
[4] A method for producing monocyclic aromatic hydrocarbons according to a
second aspect of the invention is a method for producing monocyclic aromatic
hydrocarbons in which monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms
are produced from a feedstock oil having a 10 volume percent distillation temperature of
140°C or higher and a 90 volume percent distillation temperature of 380°C or lower,
includes:
a cracking and reforming reaction step of obtaining products containing
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms and a heavy fraction
having 9 or more carbon atoms by bringing the feedstock oil into contact with a catalyst
5 for producing monocyclic aromatic hydrocarbons containing crystalline aluminosilicate
to cause a reaction,
a catalyst separation step of separating and removing the catalyst for producing
monocyclic aromatic hydrocarbons together with tricyclic aromatic hydrocarbons
contained in the products firom a mixture of the products and the catalyst for producing
10 monocyclic aromatic hydrocarbons carried by the products, both of which are derived in
the cracking and reforming reaction step,
a separation step of separating at least the monocyclic aromatic hydrocarbons
having 6 to 8 carbon atoms and a heavy fraction having 9 or more carbon atoms from a
derivative derived in the catalyst separation step,
15 a purification and recovery step of purifying and recovering the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated in the separation
step, and
a recycling step of returning the heavy fraction having 9 or more carbon atoms
which is separated in the separation step to the cracking and reforming reaction step.
20 [5] The method for producing monocyclic aromatic hydrocarbons according to
[4], including a hydrogenation reaction step of hydrogenating the heavy fraction having 9
or more carbon atoms which is separated in the separation step before the recycling step,
in which, in the recycling step, a hydrogenation reaction product of the heavy fraction
having 9 or more carbon atoms obtained in the hydrogenation reaction step is returned to
25 the cracking and reforming reaction step.
6
[6] The method for producing monocyclic aromatic hydrocarbons according to
[5], including a hydrogen recovery step of recovering hydrogen which is generated as a
by-product in the cracking and reforming reaction step from products obtained in the
cracking and reforming reaction step, and a hydrogen supply step of supplying hydrogen
5 recovered in the hydrogen recovery step to the hydrogenation reaction step.
[7] The method for producing monocyclic aromatic hydrocarbons according to
any one of [4] to [6], in which the separation step includes a tricyclic aromatic
hydrocarbon supply step of supplying tricyclic aromatic hydrocarbons separated from the
derivative which is derived in the catalyst separation step to the catalyst separation step.
Advantageous Effects of Invention
[0009]
According to the method for producing monocyclic aromatic hydrocarbons of
the invention, it is possible to produce monocyclic aromatic hydrocarbons having 6 to 8
15 carbon atoms at a high yield from a feedstock oil containing a polycyclic aromatic
hydrocarbon.
Particularly, since the products derived in the cracking and reforming reaction
step and a small amount of the catalyst for producing monocyclic aromatic hydrocarbons
carried by the products are separated and removed in the catalyst separation step, it is
20 possible to carry out subsequent treatments without causing a clogging problem or any
adverse influence on devices.
BRIEF DESCRIPTION OF DRAWINGS
[OO lo]
FIG. 1 is a view for describing an embodiment (first embodiment) of a method
7
for producing monocyclic aromatic hydrocarbons according to a first aspect of the
invention.
FIG. 2 is a schematic configuration view of a production plant for an
embodiment (second embodiment) of a method for producing monocyclic aromatic
hydrocarbons according to a second aspect of the invention.
FIG. 3 is a schematic configuration view of a production plant for an
embodiment (third embodiment) of a method for producing monocyclic aromatic
hydrocarbons according to a second aspect of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[OOll]
"First Embodiment"
An embodiment of a method for producing monocyclic aromatic hydrocarbons
according to a first aspect of the invention will be described.
The method for producing monocyclic aromatic hydrocarbons according to the
present embodiment is a method for producing monocyclic aromatic hydrocarbons in
which monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms are produced from
a feedstock oil including the following steps (a) to (f). In addition, FIG. 1 is a schematic
configuration view of a production plant for describing the embodiment.
[OO 121
(a) A cracking and reforming reaction step of obtaining products containing
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms and a heavy fraction
having 9 or more carbon atoms by bringing a feedstock oil into contact with a catalyst for
producing monocyclic aromatic hydrocarbons using a cracking and reforming reactor 10
to cause a reaction.
8
(b) A catalyst separation step of separating and removing the catalyst for
producing manocyclic aromatic hydrocarbons together with tricyclic aromatic
hydrocarbons contained in the products using a cleaning tower 12 and a catalyst
separation apparatus 14 from a mixture of the products and the catalyst for producing
monocyclic aromatic hydrocarbons carried by the products, both of which are derived in
the cracking and reforming reaction step.
(c) A separation step of separating at least the monocyclic aromatic
hydrocarbons (benzene/toluene/xylene) having 6 to 8 carbon atoms and a heavy fraction
having 9 or more carbon atoms from a derivative derived in the catalyst separation step
using a first separation apparatus 16 and a second separation apparatus 18,
(d) A purification and recovery step of purifying and recovering the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated in the separation
step using a purification and recovery apparatus 20.
(e) A tricyclic aromatic hydrocarbon supply step of supplying tricyclic aromatic
hydrocarbons separated from the derivative which is derived in the catalyst separation
step in the separation step to the catalyst separation step using returning lines 24 and 26.
(f) A hydrogen recovery step of recovering hydrogen which is generated as a
by-product in the cracking and reforming reaction step from gas components separated in
the separation step using a hydrogen recovery apparatus 30.
[00 131
Among the steps (a) to (f), the steps (a), (b) and (d) are the essential steps of the
first aspect, and the steps (c), (e) and (f) are arbitrary steps.
Hereinafter, the respective steps will be specifically described.
[00 141

9
In the cracking and reforming reaction step (a), a feedstock oil is introduced into
a cracking and reforming reactor 10 filled with a catalyst for producing monocyclic
aromatic hydrocarbons, brought into contact with the catalyst for producing monocyclic
aromatic hydrocarbons, and reacted with the catalyst. Then, using saturated
hydrocarbons contained in the feedstock oil as a hydrogen donor, polycyclic aromatic
hydrocarbons are partially hydrogenated through a hydrogen transfer reaction from the
saturated hydrocarbons, and the rings are opened, thereby converting the polycyclic
aromatic hydrocarbons into monocyclic aromatic hydrocarbons. In addition, the
polycyclic aromatic hydrocarbons can be converted into monocyclic aromatic
hydrocarbons by cyclizing and dehydrogenating saturated hydrocarbons that are
contained in the feedstock oil or obtained in the cracking step. Furthermore,
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms can also be obtained by
cracking monocyclic aromatic hydrocarbons having 9 or more carbon atoms.
[00 151
However, since tricyclic aromatic hydrocarbons have a low reactivity in the
cracking and reforming reaction step in spite of being a hydrogenation reaction product,
tricyclic aromatic hydrocarbons are rarely converted to monocyclic aromatic
hydrocarbons, and, instead, derived together with other products. The products contain
hydrogen, methane, ethane, LPG, a heavy fraction having 9 or more carbon atoms, and
the like in addition to monocyclic aromatic hydrocarbons.
In addition, in the cracking and reforming reaction step, when the products are
derived, a small amount of the catalyst for producing monocyclic aromatic hydrocarbons
is derived due to the products carrying the catalyst. Therefore, in the cracking and
reforming reaction step, a mixture of the products and the catalyst for producing
monocyclic aromatic hydrocarbons is derived from the cracking and reforming reactor
[00 161
(Feedstock oil)
A feedstock oil used in the embodiment is an oil having a 10 volume percent
distillation temperature of 140°C or higher and a 90 volume percent distillation
temperature of 380°C or lower. When an oil having a 10 volume percent distillation
temperature of lower than 140°C is used, monocyclic aromatic hydrocarbons are
produced from a light oil, and therefore the oil becomes unsuitable for the purpose of the
embodiment that produces monocyclic aromatic hydrocarbons from the feedstock oil
containing polycyclic aromatic hydrocarbons. In addition, in a case in which an oil
having a 90 volume percent distillation temperature of higher than 380°C is used, the
yield of monocyclic aromatic hydrocarbons is lowered such that there is a tendency that
the amount of coke sediment on the catalyst for producing monocyclic aromatic
hydrocarbons increases and thus the activity of the catalyst abruptly decreases.
The 10 volume percent distillation temperature of the feedstock oil is preferably
150°C or higher, and the 90 volume percent distillation temperature of the feedstock oil
is preferably 360°C or lower.
[00 171
The 10 volume percent distillation temperature and the 90 volume percent
distillation temperature mentioned herein refer to values measured based on JIS K 2254
"Petroleum Products-Determination of Distillation Characteristics".
Examples of the feedstock oil having a 10 volume percent distillation
temperature of 140°C or higher and a 90 volume percent distillation temperature of
380°C or lower include light cycle oils (LCO) produced in fluidized catalytic crackers,
11
hydro-refined oils of LCOs, coal-liquefied oils, heavy oil hydrocracking purified oils,
straight-run kerosene, straight-run light oils, coker kerosene, coker light oils, oil sand
hydrocracking purified oils and the like.
A polycyclic aromatic hydrocarbon is a substance which has a low reactivity and
5 is not easily converted to a monocyclic aromatic hydrocarbon in the cracking and
reforming reaction step of the embodiment. However, on the other hand, when
hydrogenated in the hydrogenation reaction step, a polycyclic aromatic hydrocarbon is
converted to naphthenobenzene, and can be converted to monocyclic aromatic
hydrocarbons when supplied back to the cracking and reforming reaction step again for
10 recycling. Therefore, the upper limit of the content of polycyclic aromatic
hydrocarbons in the feedstock oil is not particularly limited. However, among
polycyclic aromatic hydrocarbons, tri- or more-cyclic aromatic hydrocarbons consume a
large amount of hydrogen in the hydrogenation reaction step, and have a low reactivity in
the cracking and reforming reaction step even in a hydrogenated form, and therefore the
15 inclusion of a large amount of a polycyclic aromatic hydrocarbon is not preferable.
Therefore, the content of tri- or more-cyclic aromatic hydrocarbons in the feedstock oil is
preferably 25 volume percent or less, and more preferably 15 volume percent or less.
The feedstock oil which contains bicyclic aromatic hydrocarbons that are
converted to naphthenobenzene in the hydrogenation reaction step and have an aim to
20 reduce tri- or more-cyclic aromatic hydrocarbons preferably has a 90 volume percent
distillation temperature of, for example, 330°C or lower.
[0018]
In addition, the polycyclic aromatic hydrocarbons mentioned herein refer to the
total value of the content of bicyclic aromatic hydrocarbons (bicyclic aromatic
25 components) and the content of tri- or more-cyclic aromatic hydrocarbons (tri- or
more-cyclic aromatic components) which are measured based on JPI-5s-49 "Petroleum
Products-Determination of Hydrocarbon Types-High Performance Liquid
Chromatography" or analyzed using FID gas chromatography or two-dimensional gas
chromatography. Hereinafter, in a case in which the contents of polycyclic aromatic
5 hydrocarbons, bicyclic aromatic hydrocarbons and tri- or more-cyclic aromatic
hydrocarbons are indicated using volume percent, the contents will be values measured
based on JPI-5s-49, and, in a case in which the contents are indicated using mass percent,
the contents will be values measured based on FID gas chromatography or
I two-dimensional gas chromatography.
I 10 [00 191
(Reaction type)
The reaction type when bringing the feedstock oil into contact with the catalyst
for producing monocyclic aromatic hydrocarbons to cause a reaction, that is, the reaction
type of the cracking and reforming reactor 10 can include a fixed bed type, a moving bed
15 type, a fluidized bed type or the like.
In the embodiment, since a heavy component is used as the raw material, a
fluidized bed type is preferable since a coke component deposited to the catalyst can be
continuously removed and the reaction can be stably carried out, and a continuous
regeneration-type fluidized bed is particularly preferable since the catalyst is circulated
20 between the reactor and a regenerator and the reaction and the regeneration can be
continuously repeated. Generally, there are a bed cracking-type fluidized bed and a
riser cracking-type fluidized bed; however, in the case of the embodiment, the reaction is
desirably carried out under mild conditions using a bed cracking-type fluidized bed.
The feedstock oil when brought in contact with the catalyst for producing monocyclic
25 aromatic hydrocarbons is preferably in a gaseous state. In addition, the raw material
13
may be diluted using gas if necessary.
[0020]
(Catalyst for producing monocyclic aromatic hydrocarbons)
The catalyst for producing monocyclic aromatic hydrocarbons contains
crystalline aluminosilicate.
[002 11
[Crystalline aluminosilicate]
The crystalline aluminosilicate is preferably a middle-pore zeolite andlor a
large-pore zeolite since the yield of monocyclic aromatic hydrocarbons can be further
increased.
The middle-pore zeolite is a zeolite having a skeleton structure with a
10-membered ring, and examples of the middle-pore zeolite include zeolites having AEL
type, EUO type, FER type, HEU type, MEL type, MFI type, NES type, TON type and
WE1 type crystal structures. Among the above zeolites, an MFI-type zeolite is
preferable since the yield of monocyclic aromatic hydrocarbons can be further increased.
The large-pore zeolite is a zeolite having a skeleton structure with a
12-membered ring, and examples of the large-pore zeolite include zeolites having AFI
type, AT0 type, BEA type, CON type, FAU type, GME type, LTL type, MOR type,
MTW type and OFF type crystal structures. Among the above zeolites, BEA-type,
FAU-type and MOR-type zeolites are preferable due to their industrial applicability, and
a BEA-type zeolite is preferable since the yield of monocyclic aromatic hydrocarbons
can be further increased.
roo221
The crystalline aluminosilicate may contain a small-pore zeolite having a
skeleton structure with a 10 or less-membered ring and an ultra large-pore zeolite having
14
a skeleton structure with a 14 or more-membered ring in addition to the middle-pore
zeolite and the large-pore zeolite.
Here, examples of the small-pore zeolite include zeolites having ANA type,
CHA type, ERI type, GIs type, KFI type, LTA type, NAT type, PAU type and YUG type
crystal structures.
Here, examples of the ultra large-pore zeolite include zeolites having CLO type
and VPI type crystal structures.
[0023]
In a case in which a fixed bed-type reaction is employed in the cracking and
reforming reaction step, the content of the crystalline aluminosilicate in the catalyst for
producing monocyclic aromatic hydrocarbons is preferably in a range of 60% by mass to
100% by mass, more preferably in a range of 70% by mass to 100% by mass, and
particularly preferably in a range of 90% by mass to 100% by mass when the content of
the entire catalyst for producing monocyclic aromatic hydrocarbons is set to 100% by
mass. When the content of the crystalline aluminosilicate is 60% by mass or more, the
yield of monocyclic aromatic hydrocarbons can be sufficiently increased.
In a case in which a fluidized bed-type reaction is employed in the cracking and
reforming reaction step, the content of the crystalline aluminosilicate in the catalyst for
producing monocyclic aromatic hydrocarbons is preferably in a range of 20% by mass to
60% by mass, more preferably in a range of 30% by mass to 60% by mass, and
particularly preferably in a range of 35% by mass to 60% by mass when the content of
the entire catalyst for producing monocyclic aromatic hydrocarbons is set to 100% by
mass. When the content of the crystalline aluminosilicate is 20% by mass or more, the
yield of monocyclic aromatic hydrocarbons can be sufficiently increased. When the
content of the crystalline aluminosilicate exceeds 60% by mass, the content of a binder
that can be incorporated into the catalyst decreases, and thus there are cases in which the
catalyst becomes unsuitable for a fluidized bed-type reaction.
[0024]
[Phosphorous and boron]
5 The catalyst for producing monocyclic aromatic hydrocarbons preferably
contains phosphorous and/or boron. When the catalyst for producing monocyclic
aromatic hydrocarbons contains phosphorous and/or boron, it is possible to prevent the
yield of monocyclic aromatic hydrocarbons from decreasing over time, and the
generation of coke on the surface of the catalyst can be suppressed.
10 [0025]
Examples of a method for adding phosphorous to the catalyst for producing
monocyclic aromatic hydrocarbons include a method of supporting phosphorous in the
crystalline alurninosilicate, crystalline gallo-aluminosilicate or crystalline
zinco-aluminosilicate using tan ion-exchange method, an impregnation method or the like,
15 a method of adding a phosphorous compound during the synthesis of a zeolite so as to
substitute some of the crystalline aluminosilicate in the skeleton with phosphorous, a
method of using a crystallization accelerator containing phosphorous during the synthesis
of a zeolite, and the like. A phosphate ion-containing aqueous solution used at this time
is not particularly limited, but an aqueous soluti.on prepared by dissolving phosphoric
20 acid, ammonium phosphate dibasic, ammonium dihydrogen phosphate or other
water-soluble phosphate at an arbitrary concentration can be preferably used.
Examples of a method for adding boron to the catalyst for producing monocyclic
aromatic hydrocarbons include a method of supporting boron in the crystalline
aluminosilicate, crystalline gallo-aluminosilicate or crystalline zinco-aluminosilicate
25 using an ion-exchange method, an impregnation method or the like, a method of adding a
boron compound during the synthesis of a zeolite so as to substitute some of the
crystalline aluminosilicate in the skeleton with boron, a method of using a crystallization
accelerator containing boron during the synthesis of a zeolite, and the like.
[0026]
5 The content of phosphorous and/or boron in the catalyst for producing
monocyclic aromatic hydrocarbons is preferably in a range of 0.1% by mass to 10% by
mass, more preferably in a range of 0.5% by mass to 9% by mass, and particularly
preferably in a range of 0.5% by mass to 8% by mass when the content of the entire
catalyst for producing monocyclic aromatic hydrocarbons is set to 100% by mass.
10 When the content of phosphorous and/or boron with respect to the total mass of the
catalyst is 0.1% by mass or more, it is possible to prevent the yield of monocyclic
aromatic hydrocarbons from decreasing over time, and, when the content is 10% by mass
or less, the yield of monocyclic aromatic hydrocarbons can be increased.
[0027]
15 [Gallium and zinc]
The catalyst for producing monocyclic aromatic hydrocarbons can contain
gallium andlor zinc as necessary. When the catalyst for producing monocyclic aromatic
hydrocarbons contains gallium and/or zinc, it is possible to increase the generation
proportion of monocyclic aromatic hydrocarbons.
20 [0028]
Regarding the format of the inclusion of gallium in the catalyst for producing
monocyclic aromatic hydrocarbons, the catalyst can contain gallium incorporated into the
lattice skeleton of the crystalline aluminosilicate (crystalline aluminosilicate), can contain
gallium supported in the crystalline aluminosilicate (gallium-supported crystalline
25 aluminosilicate), or can contain gallium both incorporated into the lattice skeleton of the
crystalline aluminosilicate and supported in the crystalline aluminosilicate.
Regarding the format of the inclusion of zinc in the catalyst for producing
monocyclic aromatic hydrocarbons, the catalyst can contain zinc incorporated into the
lattice skeleton of the crystalline aluminosilicate (crystalline zinco-aluminosilicate), can
5 contain zinc supported in the crystalline aluminosilicate (zinc-supported crystalline
aluminosilicate), or can contain zinc both incorporated into the lattice skeleton of the
crystalline aluminosilicate and supported in the crystalline aluminosilicate.
[0029]
The crystalline gallo-aluminosilicate and the crystalline zinco-aluminosilicate
10 have a structure including Si04, A104 and Ga04/Zn04 structures in the skeletons. In
addition, the crystalline gallo-aluminosilicate and the crystalline zinco-aluminosilicate
can be obtained using, for example, gel crystallization through hydrothermal synthesis, a
method of inserting gallium or zinc into the lattice skeleton of the crystalline
aluminosilicate or a method of inserting aluminum into the lattice skeleton of the
15 crystalline gallo-aluminosilicate or the crystalline zinco-aluminosilicate.
[0030]
The gallium-supported crystalline aluminosilicate contains gallium supported in
the crystalline aluminosilicate using a well-known method such as an ion-exchange
method or an impregnation method. A gallium source used at this time is not
20 particularly limited, and examples thereof include gallium salts such as gallium nitrate
and gallium chloride, gallium oxides and the like.
The zinc-supported crystalline aluminosilicate contains zinc supported in the
crystalline alurninosilicate using a well-known method such as an ion-exchange method
or an impregnation method. A zinc source used at this time is not particularly limited,
25 and examples thereof include zinc salts such as zinc nitrate and zinc chloride, zinc oxides
and the like.
[003 11
In a case in which the catalyst for producing monocyclic aromatic hydrocarbons
contains gallium and/or zinc, the content of gallium and/or zinc in the catalyst for
5 producing monocyclic aromatic hydrocarbons is preferably in a range of 0.01% by mass
to 5.0% by mass, and more preferably in a range of 0.05% by mass to 2.0% by mass
when the content of the entire catalyst is set to 100% by mass. When the content of
gallium and/or zinc is 0.01% by mass or more, it is possible to increase the generation
proportion of monocyclic aromatic hydrocarbons, and, when the content is 5.0% by mass
10 or less, the yield of monocyclic aromatic hydrocarbons can be further increased.
[0032]
[Shape]
The catalyst for producing monocyclic aromatic hydrocarbons is given, for
example, a powder form, a grain form, a pellet form or the like depending on the reaction
15 type. For example, the catalyst is given a powder form in the case of a fluidized bed as
in the embodiment, and the catalyst is given a grain form or a pellet form in the case of a
fixed bed as in another embodiment. The average grain diameter of the catalyst used in
a fluidized bed is preferably in a range of 30 pm to 180 pm, and more preferably in a
range of 50 pm to 100 pm. In addition, the bulk density of the catalyst used in a
20 fluidized bed is preferably in a range of 0.4 glcc to 1.8 glcc, and more preferably in a
range of 0.5 glcc to 1 .O glcc.
The average grain diameter refers to the grain diameter located at 50% by mass
in a grain diameter distribution obtained by classification using a sieve, and the bulk
density is a value measured using the method of Standard No. JIS R 9301-2-3.
In a case in which a grain-form or pellet-form catalyst is obtained, it is possible
19
to incorporate an oxide that is inactive to the catalyst as a binder as necessary and then
mold the catalyst using a variety of molding machines.
[0033]
In a case in which the catalyst for producing monocyclic aromatic hydrocarbons
contains an inorganic oxide such as a binder, a phosphorous-containing substance may be
used as the binder.
COO341
(Reaction temperature)
The reaction temperature when the feedstock oil is brought into contact with the
catalyst for producing monocyclic aromatic hydrocarbons so as to react with the catalyst
is not particularly limited, but the reaction temperature is preferably in a range of 400°C
to 650°C. When the lower limit of the reaction temperature is 400°C or higher, it is
possible to facilitate the reaction of the feedstock oil, and the lower limit is preferably
450°C or higher. In addition, when the upper limit of the reaction temperature is 650°C,
it is possible to suficiently increase the yield of monocyclic aromatic hydrocarbons, and
the upper limit is preferably 600°C or lower.
1003 51
(Reaction pressure)
The reaction pressure when the feedstock oil is brought into contact with the
catalyst for producing monocyclic aromatic hydrocarbons so as to react with the catalyst
is preferably set to 1.5 MPaG or less, and more preferably set to 1.0 MPaG or less.
When the reaction pressure is 1.5 MPaG or less, the generation of a byproduct of a light
gas can be suppressed, and thus it is possible to use a reaction apparatus with a low
pressure resistance.
[0036]
(Contact time)
The contact time between the feedstock oil and the catalyst for producing
monocyclic aromatic hydrocarbons is not particularly limited as long as a substantially
5 desired reaction proceeds, but is preferably in a range of 1 second to 300 seconds in
terms of, for example, the time for gas to pass through the catalyst for producing
monocyclic aromatic hydrocarbons, and, furthermore, it is more preferable to set the
lower limit to 5 seconds and the upper limit to 150 seconds. When the contact time is 1
second or more, it is possible to ensure the reaction of all the feedstock oil, and, when the
10 contact time is 300 seconds or less, the accumulation of carbonaceous substances on the
catalyst due to excessive coking and the like can be suppressed. In addition, the amount
of a light gas generated due to decomposition can be suppressed.
[003 71

15 In the catalyst separation step (b), the catalyst is removed from the mixture of
the products and the catalyst for producing monocyclic aromatic hydrocarbons
(hereinafter, sometimes, simply referred to as catalyst) carried by the products, both of
which are derived in the cracking and reforming reaction step (cracking and reforming
reactor 10). In addition, the tricyclic aromatic hydrocarbons contained in the products
20 are also separated and removed.
[0038]
That is, the catalyst separation step is configured to include the cleaning tower
12 to which the mixture is supplied and a catalyst separator 14 that separates a heavy
fraction derived from the cleaning tower 12 into solid and liquid so as to separate and
25 remove the catalyst.
2 1
The operation in the cleaning tower 12 will be described.
The vapor of the product from the cracking and reforming reactor 10 is supplied
to a lower portion of the cleaning tower 12. In the cleaning tower 12, after a tower
bottom liquid of the cleaning tower 12 leaks, the pressure is increased using a pump, and
the liquid is cooled using a heat exchanger, circulated to the middle of the cleaning tower
12. In the cleaning tower 12, a reaction product of the vapor and the circulated liquid
make a countercurrent contact so that catalyst particles which are contained in the
reaction product in a small amount and carried from the cracking and reforming reactor
10 are trapped by the circulated liquid, whereby it is possible to remove the catalyst
particles from the reaction product. However, the circulated liquid is also circulated,
and therefore the circulated liquid in the middle of the cleaning tower 12 also contains a
small amount of the catalyst. In a case in which gas and liquid are brought into
countercurrent contact with each other, it is not possible to prevent liquid droplets from
carrying the catalyst particles, and thus the liquid droplets also contain the catalyst, and
therefore, consequently, an extremely small amount of the catalyst remains in the vapor
of the reaction product. In order to trap and separate the liquid droplets containing the
carried catalyst particles, a heavy fraction separated using the first separation apparatus
16 containing no catalyst and lor a heavy fraction (containing a large amount of tricyclic
aromatic hydrocarbons) separated in the purification and recovery step are supplied to the
top portion of the cleaning tower 12. As such, the catalyst particles are removed using a
two-step treatment in which a majority of the catalyst is removed using the circulated
tower bottom liquid in the bottom portion of the cleaning tower 12, and, furthermore, the
reaction product of the vapor containing an extremely small amount of the catalyst and
the heavy fraction from the first separation apparatus 16 which contains no catalyst are
brought into countercurrent contact with each other in the top portion, thereby trapping
22
the liquid droplets containing the catalyst.
The cleaning tower 12, for example, includes a baffle tray in which
approximately three theoretical plates are set, and is a machine that separates the catalyst
from the product that is cooled and partially liquefied while circulating and cooling the
5 mixture supplied at a high temperature state (for example, 550°C) in an external cooling
machine (not illustrated). In addition, tricyclic aromatic hydrocarbons are supplied to
the cleaning tower 12 as a cleaning liquid from the separation step described below.
The cleaning liquid cleans the product in a mixed gas-liquid state in the cleaning tower
12 and causes the catalyst contained in the product to be transferred to the cleaning liquid,
10 thereby efficiently separating and removing the catalyst from the product.
[0039]
In addition, the cleaning tower 12 derives hydrogen, gas components such as
methane and ethane, light components such as LPG, monocyclic aromatic hydrocarbons
having 6 to 8 carbon atoms, monocyclic aromatic hydrocarbons having 9 or more carbon
15 atoms and some of a heavy fraction having 10 or more carbon atoms from a tower top
portion, and also derives heavy fractions such as polycyclic aromatic hydrocarbons,
mainly tricyclic aromatic hydrocarbons, or the catalyst from a tower bottom portion.
However, since tricyclic aromatic hydrocarbons are supplied to the cleaning tower 12 as
the cleaning liquid from the separation step described below, the heavy fraction derived
20 from the tower bottom portion of the cleaning tower 12 contains not all but only some of
the tricyclic aromatic hydrocarbons in the mixture in the cleaning tower 12. That is, not
all but only some of the tricyclic aromatic hydrocarbons in the mixture in the cleaning
tower 12 are derived from the tower bottom portion. The heavy fraction derived from
the tower bottom portion contains heavy fractions such as bicyclic aromatic
25 hydrocarbons in addition to tricyclic aromatic hydrocarbons.
[0040]
The catalyst separator 14 is configured to include, for example, a filter, and is a
machine that separates the heavy fraction containing the catalyst derived from the
cleaning tower 12 into solid and liquid, and separates and removes the catalyst from the
5 heavy fraction. The separated catalyst may be, for example, sent to a catalyst
regeneration tower (not illustrated), subjected to a regeneration treatment in the tower,
and then recycled to the cracking and reforming reaction step, or, when significantly
deteriorated, the catalyst may be disposed. The heavy fraction from which the catalyst
has been removed, that is, polycyclic aromatic hydrocarbons, mainly tricyclic aromatic
10 hydrocarbons, can be used as a fuel (torch oil) for, for example, heating the catalyst
regeneration tower.
[004 11

In the separation step (c), at least monocyclic aromatic hydrocarbons having 6 to
15 8 carbon atoms and a heavy fraction having 9 or more carbon atoms are separated from a
derivative derived from the tower top portion of the cleaning tower 12 (catalyst
separation step) using a plurality of separation apparatuses.
That is, the separation step is configured to include the first separation apparatus
16 and the debutanizer (second separation apparatus) 18 in the embodiment. However,
20 the separation step of the embodiment does not necessarily include the above two
separation apparatuses, and can also be made up of, for example, a sole distillation
apparatus or the like. Therefore, it is also possible not to install the debutanizer (second
separation apparatus) 18. In addition, the separation step may be configured to include
a third separation apparatus 22 described below as necessary.
2 5 100421
24
The first separation step 16 separates hydrogen, gas components such as
methane and ethane, and a liquid fraction from the derivative. A well-known gas-liquid
separation apparatus can be used as the first separation apparatus 16. Examples of the
gas-liquid separation apparatus include an apparatus equipped with a gas-liquid
separation tank, a production introduction tube through which a product is introduced
into the gas-liquid separation tank, a gas component outflow tube provided in a top
portion of the gas-liquid separation tank and a liquid component outflow tube provided in
a bottom portion of the gas-liquid separation tank.
In the embodiment, two gas-liquid separation apparatuses are disposed, the
liquid fraction is cooled in a former stage 16a so as to separate heavy fractions mainly
containing tricyclic aromatic hydrocarbons (hereinafter referred to as tricyclic aromatic
hydrocarbons), and the pressure is increased in a latter stage 16b, thereby separating the
gas components and the liquid fraction from which the tricyclic aromatic hydrocarbons
have been separated.
The debutanizer 18 (second separation apparatus) separates LPG fractions
containing butane and the like and rough aromatic fractions containing a large amount of
monocyclic aromatic hydrocarbons having 6 or more carbon atoms from the liquid
fraction separated using the first separation apparatus 16.
[0043]
(Tricyclic aromatic hydrocarbon supply step >
The tricyclic aromatic hydrocarbons separated in the former stage 16a (first
separation apparatus 16) of the first separation apparatus 16 are returned to the cleaning
tower 12 (catalyst separation step) as the cleaning liquid using a first returning line 24.
That is, the tricyclic aromatic hydrocarbon supply step (e) in which the tricyclic aromatic
hydrocarbons are supplied to the catalyst separation step as the cleaning liquid using the
first returning line 24 is configured.
The tricyclic aromatic hydrocarbon supply step of the embodiment is not
necessarily made up of only the first returning line 24, and, for example, may be made up
of a second returning line 26 described below or both the first returning line 24 and the
second returning line 26. Furthermore, it is also possible to separate the tricyclic
aromatic hydrocarbons in any process behind the first separation apparatus 16 and to
supply the hydrocarbons to the catalyst separation step as the cleaning liquid, and, in this
case, a supply step of the tricyclic aromatic hydrocarbons also serves as the tricyclic
aromatic hydrocarbon supply step.
When the tricyclic aromatic hydrocarbons are supplied to the cleaning tower 12
as the cleaning liquid, it is possible to clean the product in a mixed gas-liquid state in the
cleaning tower 12, transfer the catalyst contained in the product to the cleaning liquid,
efficiently separate and remove the catalyst from the product. Some of the tricyclic
aromatic hydrocarbons supplied to the cleaning tower 12 are sent to the catalyst separator
14 together with the catalyst. In addition, the remaining hydrocarbons remain in the
cleaning tower 12 or are sent to the first separation apparatus 16.
[0044]

The purification and recovery step (d) purifies and recover s the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated in the separation
step using the purification and recovery apparatus 20.
The purification and recovery apparatus 20 separates monocyclic aromatic
hydrocarbons having 6 to 8 carbon atoms (benzene/toluene/xylene) and the heavy
fraction, that is, a fraction made up of, mainly, a heavy fraction having 9 or more carbon
atoms from the rough aromatic fraction obtained using the debutanizer 18. In addition,
26
the apparatus further purifies the separated monocyclic aromatic hydrocarbons having 6
to 8 carbon atoms, and respectively recovers benzene, toluene and xylene. A
well-known distillation apparatus, for example, a multi-stage distillation apparatus, such
as a stripper, can be used as the purification and recovery apparatus 20.
[0045]
The third separation apparatus 22 separates a heavy fraction having 9 carbon
atoms and a heavy fraction having 10 or more carbon atoms from the heavy fraction
separated from the purification and recovery apparatus 20. In addition, the heavy
fiaction having 9 carbon atoms is recovered and used for a base material of a variety of
products and the like. The heavy fraction having 10 or more carbon atoms is returned to
the cracking and reforming reaction step, and sent to the recycling step in order to be
provided to the cracking and reforming reaction in the cracking and reforming reactor 10
together with the feedstock oil. However, the third separation apparatus 22 is not an
essential component in the embodiment, and the heavy fraction having 9 or more carbon
atoms, which has been separated from the purification and recovery apparatus 20, may be
sent to the recycling step without passing through the third separation apparatus.
[0046]
Here, the heavy fraction separated from the monocyclic aromatic hydrocarbons
having 6 to 8 carbon atoms in the purification and recovery apparatus 20 is a heavy
fraction having 9 or more carbon atoms, and contains polycyclic aromatic hydrocarbons
as a main component and a large amount of naphthalene and alkyl naphthalenes. In
addition, the heavy fraction contains a small amount of tricyclic aromatic hydrocarbons.
That is, tricyclic aromatic hydrocarbons that cannot be separated in the cleaning tower 12
and the first separation apparatus 16 are contained in the heavy fraction. Therefore,
tricyclic aromatic hydrocarbons are separated in a form of a heavy fraction having 10 or
more carbon atoms using the third separation apparatus 22.
[0047]
As described above, the tricyclic aromatic hydrocarbons have a low reactivity in
the cracking and reforming reaction step in spite of being a hydrogenation reaction
5 product, and are rarely converted to monocyclic aromatic hydrocarbons, and therefore the
tricyclic aromatic hydrocarbons do not contribute to the improvement of the reaction
efficiency even when recycled in the cracking and reforming reaction step.
Therefore, it is also possible to let the third separation apparatus 22 not only
separate the heavy fraction separated fiom the monocyclic aromatic recover apparatus 20
10 into a heavy fraction having 9 carbon atoms and a heavy fraction having 10 or more
carbon atoms, but also separate tricyclic aromatic hydrocarbons from the heavy fraction
having 9 or more carbon atoms. In addition, the separated tricyclic aromatic
hydrocarbons are returned to the cleaning tower 12 (catalyst separation step) as the
cleaning liquid using the second returning line 26. In this case, the second returning
15 line 26 also configures the tricyclic aromatic hydrocarbon supply step in which the
tricyclic aromatic hydrocarbons are supplied to the catalyst separation step as the
cleaning liquid together with the first returning line 24 as described above.
[0048]
However, the amount of tricyclic aromatic hydrocarbons separated using the
20 third separation apparatus 22 is not large. Therefore, in consideration of an increase in
the apparatus cost or the operation cost due to the separation of tricyclic aromatic
hydrocarbons, in a case in which the economic effect of the separation and returning of
tricyclic aromatic hydrocarbons is small, the step need not include the separation of
tricyclic aromatic hydrocarbons using the third separation apparatus 22.
2 5 [0049]

In the hydrogen recovery step (f), hydrogen which is generated as a by-product
in the cracking and reforming reaction step (cracking and reforming reactor 10) is
recovered from the gas components separated in the separation step (the latter stage 16b
5 of the first separation apparatus 16) using a hydrogen recovery apparatus 30.
A method for recovering hydrogen is not particularly limited as long as
hydrogen contained in the gas components obtained in the separation step and other gases
can be separated, and examples thereof include a pressure swing adsorption method (PSA
method), a low temperature separation method, a membrane separation method and the
10 like. Therefore, an apparatus that recovers hydrogen based on the above method (for
example, a PSA apparatus) can be used as the hydrogen recovery apparatus 30.
Generally, the amount of hydrogen recovered in the hydrogen recovery step
becomes larger than a necessary amount for hydrogenating the heavy fraction having 10
or more carbon atoms.
15 [0050]
"Other Embodiments"
The first aspect of the invention is not limited to the first embodiment, and a
variety of modifications can be made within the scope of the purpose of the invention.
In the first embodiment, tricyclic aromatic hydrocarbons are separated and
20 removed in the catalyst separation step from the mixture derived from the cracking and
reforming reaction step, and then the obtained heavy fraction having 10 or more carbon
atoms is returned to the cracking and reforming reaction step. In this method, the heavy
fraction returned to the cracking and reforming reaction step rarely contains tricyclic
aromatic hydrocarbons which are not easily converted to monocyclic aromatic
25 hydrocarbons in the cracking and reforming reaction step, and thus the conversion
29
efficiency of the recycled heavy fraction (or the hydrogenation reaction product thereof)
to monocyclic aromatic hydrocarbons improves. Therefore, the overall yield of
monocyclic aromatic hydrocarbons with respect to the supply amount of the feedstock oil
improves, and it is possible to increase the yield of monocyclic aromatic hydrocarbons
5 having 6 to 8 carbon atoms.
[005 11
In addition, since tricyclic aromatic hydrocarbons are separated in the separation
step as well, it is possible to further decrease the content of tricyclic aromatic
hydrocarbons in the recycled heavy fraction (or the hydrogenation reaction product
10 thereof), and therefore it is possible to improve the conversion efficiency of the heavy
fraction to monocyclic aromatic hydrocarbons.
In addition, since the tricyclic aromatic hydrocarbons separated in the separation
step are supplied to the catalyst separation step as the cleaning liquid through the tricyclic
aromatic hydrocarbon supply step using the first returning line 24 or the second returning
15 line 26, it is possible to efficiently separate and remove the catalyst in the catalyst
separation step.
[0052]
"Second Embodiment"
An embodiment of a method for producing monocyclic aromatic hydrocarbons
20 according to a second aspect of the invention will be described.
The method for producing monocyclic aromatic hydrocarbons of the present
embodiment is a method in which monocyclic aromatic hydrocarbons having 6 to 8
carbon atoms are produced from a feedstock oil, including the following steps (g) to (0).
In addition, FIG. 2 is a schematic configuration view of a production plant for describing
25 the second embodiment.
[0053]
(g) A cracking and reforming reaction step of obtaining products containing
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms and a heavy fraction
having 9 or more carbon atoms by bringing a feedstock oil into contact with a catalyst for
5 producing monocyclic aromatic hydrocarbons using the cracking and reforming reactor
10 to cause a reaction.
(h) A catalyst separation step of separating and removing the catalyst for
producing monocyclic aromatic hydrocarbons together with tricyclic aromatic
hydrocarbons contained in the products using the cleaning tower 12 and the catalyst
10 separation apparatus 14 from a mixture of the products and the catalyst for producing
monocyclic aromatic hydrocarbons carried by the products, both of which are derived in
the cracking and reforming reaction step.
(i) A separation step of separating at least the monocyclic aromatic hydrocarbons
(benzene/toluene/xylene) having 6 to 8 carbon atoms and a heavy fraction having 9 or
15 more carbon atoms from a derivative derived in the catalyst separation step using the first
separation apparatus 16 and the second separation apparatus 18,
(j) A purification and recovery step of purifying and recovering the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated in the separation
step using the purification and recovery apparatus 20.
20 (k) A hydrogenation reaction step of hydrogenating the heavy fraction having 9
or more carbon atoms which is separated in the separation step using a hydrogenation
reactor 28.
(1) A recycling step of returning a hydrogenation reaction product of the heavy
fraction having 9 or more carbon atoms obtained by the hydrogenation reaction step to
25 the cracking and reforming reaction step using a recycling line 32.
3 1
(m) A tricyclic aromatic hydrocarbon supply step of supplying tricyclic aromatic
hydrocarbons separated from the derivative which is derived in the catalyst separation
step to the catalyst separation step using the returning lines 24 and 26 in the separation
step.
(n) A hydrogen recovery step of recovering hydrogen which is generated as a
by-product in the cracking and reforming reaction step from gas components separated in
the separation step using the hydrogen recovery apparatus 30.
(0) A hydrogen supply step of supplying hydrogen recovered in the hydrogen
recovery step to the hydrogenation reaction step using a hydrogen supply line 34.
[0054]
Among the steps (g) to (o), the steps (g), (h), (i), (j) and (1) are the essential steps
of the second aspect, and the steps (k), (m), (n) and (0) are arbitrary steps. Therefore, in
the recycling step (l), it is also possible to directly return the heavy fraction having 9 or
more carbon atoms which is separated in the separation step to the cracking and
reforming reaction step without passing through the hydrogenation reaction step.
Hereinafter, the respective steps will be specifically described.
[0055]

The cracking and reforming reaction step (g) can be carried out in the same
manner as the cracking and reforming reaction step (a) in the first embodiment.
100561

The catalyst separation step (h) can be carried out in the same manner as the
catalyst separation step (b) in the first embodiment.
[0057]

The separation step (i) can be carried out in the same manner as the separation
step (c) in the first embodiment.
[005 81

The tricyclic aromatic hydrocarbon supply step (m) can be carried out in the
same manner as the tricyclic aromatic hydrocarbon supply step (e) in the first
embodiment.
[0059]

The purification and recovery step (j) can be carried out in the same manner as
the purification and recovery step (d) in the first embodiment.
[0060]

15 In the hydrogenation reaction step (k), the heavy fraction having 10 or more
carbon atoms which is separated in the third separation apparatus 22 (separation step) is
hydrogenated using the hydrogenation reactor 28. Specifically, the heavy fiaction and
hydrogen are supplied to the hydrogenation reactor 28, and at least some of polycyclic
aromatic hydrocarbons (mainly bicyclic aromatic hydrocarbons) contained in the heavy
20 fiaction are hydrogenated using a hydrogenation catalyst.
The polycyclic aromatic hydrocarbons are preferably hydrogenated until only
one aromatic ring remains.
For example, naphthalene is preferably hydrogenated until the naphthalene turns
into tetralin (naphthenobenzene). When the polycyclic aromatic hydrocarbons are
25 hydrogenated until only one aromatic ring remains, the polycyclic aromatic hydrocarbons
33
are easily converted to monocyclic aromatic hydrocarbons when returned to the cracking
and reforming reaction step (cracking and reforming reactor 10).
[006 11
In addition, in order to improve the yield of monocyclic aromatic hydrocarbons
5 in the cracking and reforming reaction step, in the hydrogenation reaction step, the
content of the polycyclic aromatic hydrocarbons in the hydrogenation reaction product of
the obtained heavy fraction is preferably set to 40% by mass or less, more preferably set
to 25% by mass or less, and still more preferably set to 15% by mass or less. The
content of the polycyclic aromatic hydrocarbons in the hydrogenation reaction product is
10 preferably smaller than the content of polycyclic aromatic hydrocarbons in the feedstock
oil, and can be decreased by increasing the amount of hydrogenation catalyst or the
reaction pressure. However, it is not necessary to hydrogenate the heavy fraction until
all the polycyclic aromatic hydrocarbons turn into saturated hydrocarbons. There is a
tendency that excessive hydrogenation leads to an increase in the consumption amount of
15 hydrogen and an increase in the amount of heat generation.
COO621
In the embodiment, hydrogen generated as a byproduct in the cracking and
reforming reaction step (cracking and reforming reactor 10) is used as the hydrogen.
That is, hydrogen is recovered using the hydrogen recovery step (hydrogen recovery
20 apparatus 30) described below from the gas components obtained in the separation step
(first separation apparatus 16), and the recovered hydrogen is supplied to the
hydrogenation reaction step (hydrogenation reactor 28) using the hydrogen supply step
(hydrogen supply line 34).
[0063]
2 5 A preferable example of the reaction type of the hydrogenation reactor 28
3 4
(hydrogenation reaction step) is a fixed bed.
As the hydrogenation catalyst, a well-known hydrogenation catalyst (for
example, a nickel catalyst, a palladium catalyst, a nickel-molybdenum-based catalyst, a
cobalt-molybdenum-based catalyst, a nickel-cobalt-molybdenum-based catalyst, a
nickel-tungsten-based catalyst or the like) can be used.
The hydrogenation reaction temperature differs depending on the hydrogenation
catalyst used, and is generally in a range of 100°C to 450°C, more preferably in a range
of 200°C to 400°C, and still more preferably in a range of 250°C to 380°C.
[0064]
The hydrogenation reaction pressure differs depending on the hydrogenation
catalyst or raw material used, but is preferably set in a range of 0.7 MPa to 13 MPa, more
preferably set in a range of 1 MPa to 10 MPa, and particularly preferably set in a range of
1 MPa to 7 MPa. When the hydrogenation reaction pressure is set to 13 MPa or less, it
is possible to use a hydrogenation reactorwith a low pressure resistance, which can
decrease the facility cost.
On the other hand, the hydrogenation reaction pressure is preferably 0.7 MPa or
more in terms of the yield of the hydrogenation reaction.
[0065]
The consumption amount of hydrogen is preferably 3000 scfb (506 Nm3/rn3) or
less, more preferably 2500 scfb (422 ~ m ~ l omr le~ss), a nd still more preferably 1500 scfb
(253 Nm3/m3) or less.
On the other hand, the consumption amount of hydrogen is preferably 300 scfb
(50 ~ m ~ lomr m~or)e in terms of the yield of the hydrogenation reaction.
The liquid hourly space velocity (LHSV) of the heavy fraction is preferably set
in a range of 0.1 h-' to 20 h-', and more preferably set in a range of 0.2 h" to 10 h-'.
3 5
When LHSV is set to 20 h-' or less, the polycyclic aromatic hydrocarbons can be
sufficiently hydrogenated at a lower hydrogenation reaction pressure. On the other
hand, when LHSV is set to 0.1 h-' or more, it is possible to prevent an increase in the size
of the hydrogenation reactor.
[0066]

In the recycling step (I), the hydrogenation reaction product of the heavy fraction
obtained in the hydrogenation reaction step and the feedstock oil are returned to the
cracking and reforming reaction step in a form of a mixture with the feedstock oil
10 produced using the recycling line 32 or separately from the feedstock oil.
When the hydrogenation reaction product of the heavy fraction is returned to the
cracking and reforming reaction step, monocyclic aromatic hydrocarbons can be obtained
using the heavy fraction which has been a byproduct as a raw material. Therefore, the
amount of byproduct can be decreased so that-it is possible to increase the generation
15 amount of monocyclic aromatic hydrocarbons, whereby the production efficiency of
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms can be increased. In
addition, since hydrogenation also generates saturated hydrocarbons, it is also possible to
accelerate a hydrogen transfer reaction in the cracking and reforming reaction step.
Furthermore, since the hydrogenation reaction product of the heavy fraction
20 returned to the cracking and reforming reaction step in the recycling step (recycling line
32) rarely contains tricyclic aromatic hydrocarbons that are not easily converted to
monocyclic aromatic hydrocarbons in the cracking and reforming reaction step, the
conversion efficiency of the recycled hydrogenation reaction product to monocyclic
aromatic hydrocarbons improves.
Based on what has been described above, the overall yield of monocyclic
36
aromatic hydrocarbons with respect to the supply amount of the feedstock oil improves,
and therefore it is possible to increase the yield of monocyclic aromatic hydrocarbons
having 6 to 8 carbon atoms.
[0067]
5 In the recycling step, it is not necessary to recycle the entire hydrogenation
reaction product to the feedstock oil of the cracking and reforming reaction step at all
times. In this case, the hydrogenation reaction product which is not recycled can be
used as, for example, a base fuel material.
In addition, in the embodiment, the heavy fraction having 10 or more carbon
10 atoms obtained using the third separation apparatus 22 (separation step) is returned to the
cracking and reforming reaction step after being hydrogenated, but the heavy fraction
may be returned to the cracking and reforming reaction step with no hydrogenation
treatment. In this case as well, since the recycled oil rarely contains tricyclic aromatic
hydrocarbons, the conversion efficiency of the recycled oil to monocyclic aromatic
15 hydrocarbons improves.
In addition, the heavy fraction having 9 or more carbon atoms separated from
the purification and recovery apparatus 20 may be directly provided to the hydrogenation
reactor 28 (hydrogenation reaction step) or the cracking and reforming reactor 10
(cracking and reforming reaction step) without separating the heavy fraction separated
20 from the purification and recovery apparatus 20 into the heavy fraction having 9 carbon
atoms and the heavy fraction having 10 or more carbon atoms using the third separation
apparatus 22.
[0068]

In the hydrogen recovery step (n), hydrogen generated as a byproduct in the
3 7
cracking and reforming reaction step (cracking and reforming reactor 10) is recovered
from the gas components obtained in the separation step (the latter stage 16b of the first
separation apparatus 16) using the hydrogen recovery apparatus 30.
A method for recovering hydrogen is not particularly limited as long as
5 hydrogen contained in the gas components obtained in the separation step and other gases
can be separated, and examples thereof include a pressure swing adsorption method (PSA
method), a low temperature separation method, a membrane separation method and the
like. Therefore, an apparatus that recovers hydrogen based on the above method (for
example, a PSA apparatus) can be used as the hydrogen recovery apparatus 30.
Generally, the amount of hydrogen recovered in the hydrogen recovery step
becomes larger than a necessary amount for hydrogenating the heavy fraction having 9 or
more carbon atoms.
[0069]

15 In the hydrogen supply step (o), the hydrogen obtained in the hydrogen recovery
step (hydrogen recovery apparatus 30) is supplied to the hydrogenation reaction step
(hydrogenation reactor 28) using the hydrogen supply line 34. The supply amount of
hydrogen at this time is adjusted depending on the amount of heavy fraction supplied to
the hydrogenation reaction step. In addition, the pressure of the hydrogen is adjusted as
20 necessary.
When the hydrogen supply step of the embodiment is provided, the heavy
fraction can be hydrogenated using the hydrogen generated as a byproduct in the
cracking and reforming reaction step (cracking and reforming reactor 10). Therefore, it
is possible to decrease some or all of hydrogen supplied from an external source by
25 supplying some or all of hydrogen used in the production method of the embodiment
3 8
using hydrogen generated as a byproduct.
[0070]
In the method for producing monocyclic aromatic hydrocarbons of the
embodiment, monocyclic aromatic hydrocarbons can be obtained using the heavy
5 fraction produced as a byproduct as a raw material by returning the heavy fraction having
10 or more carbon atoms or the heavy fraction having 9 or more carbon atoms to the
cracking and reforming reaction step. Therefore, the amount of byproduct can be
decreased so that it is possible to increase the generation amount of monocyclic aromatic
hydrocarbons, whereby the production efficiency of monocyclic aromatic hydrocarbons
10 having 6 to 8 carbon atoms can be increased.
In addition, when the heavy fraction is hydrogenated in the hydrogenation
reaction step and returned to the cracking and reforming reaction step, hydrogenation
also generates saturated hydrocarbons, and therefore it is also possible to accelerate the
hydrogen transfer reaction in the cracking and reforming reaction step.
[007 11
Furthermore, since tricyclic aromatic hydrocarbons are separated and removed
from the mixture derived from the cracking and reforming reaction step in the catalyst
separation step, and the subsequently obtained heavy fraction having 10 (9) or more
carbon atoms is returned to the cracking and reforming reaction step, the heavy fraction
20 returned to the cracking and reforming reaction step rarely contains tricyclic aromatic
hydrocarbons that are not easily converted to monocyclic aromatic hydrocarbons in the
cracking and reforming reaction step, the conversion efficiency of the recycled heavy
fraction (or the hydrogenation reaction product thereof) to monocyclic aromatic
hydrocarbons improves. Therefore, the overall yield of monocyclic aromatic
25 hydrocarbons with respect to the supply amount of the feedstock oil improves, and it is
3 9
possible to increase the yield of monocyclic aromatic hydrocarbons having 6 to 8 carbon
atoms.
[0072]
In addition, since tricyclic aromatic hydrocarbons are also separated in the
5 separation step, it is possible to decrease the content of tricyclic aromatic hydrocarbons
in the recycled heavy fraction (or the hydrogenation reaction product thereof), and
therefore it is possible to improve the conversion efficiency of the heavy fraction to
monocyclic aromatic hydrocarbons.
In addition, since the tricyclic aromatic hydrocarbons separated in the separation
10 step are supplied to the catalyst separation step as the cleaning liquid through the tricyclic
aromatic hydrocarbon supply step using the first returning line 24 or the second returning
line 26, it is possible to efficiently separate and remove the catalyst in the catalyst
separation step.
[0073]
"Third Embodiment"
Another embodiment of the method for producing monocyclic aromatic
hydrocarbons according to the second aspect of the invention will be described.
FIG. 3 is a schematic configuration view of a production plant for describing the
third embodiment. Similarly to the second embodiment, the method for manufacturing
20 monocyclic aromatic hydrocarbons of the embodiment is a method in which monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms are produced from a raw material.
COO741
The differences between the third embodiment and the second embodiment
illustrated in FIG. 2 are as follows. While the cleaning step is made up of the cleaning
25 tower 12 and the catalyst separator 16, and the separation step is made up of the first
40
separation apparatus 16, the debutanizer 18 (second separation apparatus), the
purification and recovery apparatus 20 and the third separation apparatus 22 in the
second embodiment, the cleaning step is made up of a fractionator 40 and a catalyst
separator 14, and the separation step is made up of the fractionator 40, the debutanizer 18
5 (second separation apparatus), the purification and recovery apparatus 20 and the third
separation apparatus 22 in the third embodiment as illustrated in FIG. 3. That is, in the
embodiment, the fractionator 40 is used instead of the cleaning tower 12 and the first
separation apparatus 16 in the second embodiment.
[0075]
Therefore, similarly to the second embodiment, basically, the method for
producing monocyclic aromatic hydrocarbons of the embodiment is a method including
the steps (g) to (0).
Hereinafter, steps in which different apparatuses from the second embodiment
are used will be described. The same steps that use the same appa-atuses as those used
15 in the second embodiment will not be described.
[0076]
Catalyst separation step>
In the catalyst separation step, similarly to the second embodiment, the catalyst
(catalyst for producing monocyclic aromatic hydrocarbons) is removed from the mixture
20 derived from the cracking and reforming reaction step (cracking and reforming reactor
10).
In addition, the tricyclic aromatic hydrocarbons contained in the product
obtained in the cracking and reforming reaction step are also separated and removed.
[0077]
However, in the embodiment, the fractionator 40 functions as the cleaning tower
4 1
12 in the second embodiment. The fractionator 40 is a well-known distillation tower
made up of multiple phases in which the catalyst in the mixture or the heavy fraction
mainly containing tricyclic aromatic hydrocarbons is separated in the tower bottom
portion and the gas components in the mixture (the product of the cracking and reforming
5 reaction step) is separated in the tower top portion. In addition, an intermediate fraction
(liquid fraction) between the gas components and the heavy fraction mainly containing
tricyclic aromatic hydrocarbons is separated in a middle portion.
[0078]
In the tower bottom portion of the fractionator 40, the heavy fraction having a
10 high boiling point, that is, the heavy fraction mainly containing tricyclic aromatic
hydrocarbons is liquefied. Then, the heavy fraction mainly containing tricyclic
aromatic hydrocarbons is derived from the tower bottom portion together with the
catalyst.
The derived heavy fraction is supplied to the catalyst separator 14, similarly to
15 the second embodiment, and the catalyst is separated and removed in the catalyst
separator. In addition, the polycyclic aromatic hydrocarbons (heavy fraction) mainly
containing tricyclic aromatic hydrocarbons from which the catalyst has been removed are
used as, for example, a fuel (torch oil) for heating the catalyst regeneration tower.
[0079]
20
In addition, from a middle portion to a tower top portion of the fractionator 40,
similarly to the first separation apparatus 16 in the second embodiment, hydrogen, gas
components such as methane and ethane, and a liquid fraction are separated from the
fraction from which the catalyst has been removed (derivative) using a distillation
25 operation. In addition, the intermediate fraction (liquid fraction) separated from the
42
middle portion as described above is derived, and the gas components are derived from
the tower top portion.
When the gas components and the liquid fraction have been separated from the
middle portion to the tower top portion of the fractionator 40, tricyclic aromatic
5 hydrocarbons are liquefied as a part of the liquid fraction. The liquefied tricyclic
aromatic hydrocarbons are made to flow down to the tower bottom portion as a heavy
fraction, and function as a cleaning liquid for catalyst separation carried out in the tower
bottom portion. Therefore, the fractionator 40 also includes the tricyclic aromatic
hydrocarbon supply step inside.
10 [OOSO]
The intermediate fraction (liquid fraction) derived from the middle portion of the
fractionator 40 is supplied to the debutanizer 18 (second separation apparatus) so as to be
separated, and then, similarly to the second embodiment, the intermediate fraction is
sequentially separated using the purification and recovery apparatus 20 and-the third
15 separation apparatus 22. In addition, the heavy fraction having 10 or more carbon
atoms is sent to the hydrogenation reaction step (hydrogenation reactor 28) so as to be
provided to a hydrogenation reaction, and then returned to the cracking and reforming
reaction step in a form of a mixture with the feedstock oil produced using the recycling
step (recycling line 32) or separately from the feedstock oil. In a case in which tricyclic
20 aromatic hydrocarbons (the heavy fraction mainly containing tricyclic aromatic
hydrocarbons) are separated from the heavy fraction having 10 or more carbon atoms in
the third separation apparatus 22, the separated tricyclic aromatic hydrocarbons are
returned to the tower bottom portion of the fractionator 40 as the cleaning liquid through
the second returning line 26. In addition, the embodiment need not include the third
25 separation apparatus 22.
43
The gas components derived from the tower top portion of the fractionator 40
are sent to the hydrogen recovery apparatus 30 (hydrogen recovery step), and then treated
in the same manner as in the second embodiment.
[008 11
5 In the method for producing monocyclic aromatic hydrocarbons of the
embodiment as well, monocyclic aromatic hydrocarbons can be obtained using the heavy
fraction produced as a byproduct as a raw material by returning the heavy fraction having
10 or more carbon atoms or the heavy fraction having 9 or more carbon atoms to the
cracking and reforming reaction step. Therefore, the amount of byproduct can be
10 decreased so that it is possible to increase the generation amount of monocyclic aromatic
hydrocarbons, whereby the production efficiency of monocyclic aromatic hydrocarbons
having 6 to 8 carbon atoms can be increased.
In addition, when the heavy fraction is hydrogenated in the hydrogenation
reaction step and returned to the cracking and reforming reaction step, hydroge~ation
15 also generates saturated hydrocarbons, and therefore it is also possible to accelerate the
hydrogen transfer reaction in the cracking and reforming reaction step.
[0082]
Furthermore, tricyclic aromatic hydrocarbons are separated and removed from
the mixture derived from the cracking and reforming reaction step in the catalyst
20 separation step, and the subsequently obtained heavy fraction having 10 (9) or more
carbon atoms is returned to the cracking and reforming reaction step. In this method,
the heavy fraction returned to the cracking and reforming reaction step rarely contains
tricyclic aromatic hydrocarbons that are not easily converted to monocyclic aromatic
hydrocarbons in the cracking and reforming reaction step, and therefore the conversion
25 efficiency of the recycled heavy fraction (or the hydrogenation reaction product thereof)
44
to monocyclic aromatic hydrocarbons improves. Therefore, the overall yield of
monocyclic aromatic hydrocarbons with respect to the supply amount of the feedstock oil
improves, and it is possible to increase the yield of monocyclic aromatic hydrocarbons
having 6 to 8 carbon atoms.
5 In addition, since tricyclic aromatic hydrocarbons are also separated in the
separation step, it is possible to decrease the content of tricyclic aromatic hydrocarbons
in the recycled heavy fraction (or the hydrogenation reaction product thereof), and
therefore it is possible to improve the conversion efficiency of the heavy fraction to
monocyclic aromatic hydrocarbons.
[0083]
"Other Embodiments"
The second aspect of the invention is not limited to the second or third
embodiment, and a variety of modifications can be made within the scope of the purpose
of the invention.
For example, the hydrogen used in the hydrogenation reaction step is not
necessarily hydrogen generated as a byproduct in the cracking and reforming reaction
step, and hydrogen obtained using a well-known method for producing hydrogen may be
used, or hydrogen generated as a byproduct using other catalytic reforming methods may
be used.
The recycled heavy fraction may be introduced into the cracking reaction step
after being directly mixed with the feedstock oil as described above or may be introduced
separately from the feedstock oil.
EXAMPLES
(Example 1)
In the production plant illustrated in FIG. 1, LC0 having the same properties as
in Comparison Test Example 1 was provided to a cracking and reforming reactor as a
feedstock oil, and a reaction was allowed to proceed. Then, the same treatments as in
5 the first embodiment were carried out, BTX were produced through a 5-hour-long test,
and it was confirmed that a heavy fraction having 10 or more carbon atoms could be
derived from the third separation apparatus 22.
[0085]
(Comparison Test Example 1)
10 In the production plant illustrated in FIG. 2, LC0 having properties described in
the following table was provided to the cracking and reforming reactor 10 as a feedstock
oil, and a reaction was allowed to proceed. Then, the same treatments as in the second
embodiment were carried out, and a heavy fraction from which a catalyst had been
removed using the catalyst separator 14, that is, polycyclic aromatic hydrocarbons,
15 mainly tricyclic aromatic hydrocarbons were recovered. In addition, the recovered
heavy fraction was provided to the hydrogenation reactor 28 so as to cause a
hydrogenation reaction, thereby obtaining a hydrogenation reaction product of the heavy
fraction. After that, the obtained hydrogenation reaction product was provided to the
cracking and reforming reactor 10 instead of the feedstock oil, and a cracking and
20 reforming reaction was allowed to proceed. As a result of investigating the amount
(content rate) of tricyclic aromatic hydrocarbons in the heavy fraction, the amount was
approximately 42.8% by mass, and the majority of the remainder was bicyclic aromatic
hydrocarbons.
[Table 11
(Example 2)
5 In the production plant illustrated in FIG. 2, LC0 having the same properties as
Analysis
method
JIS K 2249
JIS K 2283
JIS K 2254
JPI-5s-49
Properties of raw material
in Comparison Test Example 1 was provided to the cracking and reforming reactor 10 as
a feedstock oil, and a reaction was allowed to proceed. Then, the same treatments as in
Density (measurement temperature of 15°C)
Kinetic viscosity (measurement temperature
the second embodiment were carried out, and a heavy fraction having 10 or more carbon
g/cm3
rnrn2/s
"C
"C
"C
"C
"C
% by volume
% by volume
%by volume
%by volume
%by volume
% by volume
Distillation
properties
Composition
analysis
atoms derived from the third separation apparatus 22 was recovered. In addition, the
0.906
3.640
175.5
224.5
274.0
349.5
376.0
35
8
57
23
25
9
of 30°C)
Initial boiling point
10 volume percent
distillation temperature
50 volume percent
distillation temperature
90 volume percent
distillation temperature
End point
Saturated component
Olefin component
Wholly aromatic
component
Monocyclic aromatic
component
Bicyclic aromatic
component
Tri- or more-cyclic
aromatic component
10 recovered heavy fraction was provided to the hydrogenation reactor 28 so as to cause a
[0087]
hydrogenation reaction, thereby obtaining a hydrogenation reaction product of the heavy
fraction. After that, the obtained hydrogenation reaction product was provided to the
cracking and reforming reactor 10 instead of the feedstock oil, and a cracking and
47
reforming reaction was allowed to proceed. In the third separation apparatus 22, the
recovered heavy fraction was supplied to the cracking and reforming reactor 10 without
separating tricyclic aromatic hydrocarbons. As a result of investigating the amount
(content rate) of tricyclic aromatic hydrocarbons in the heavy fraction, the amount was
5 approximately 3.1 % by mass, and the majority of the remainder was bicyclic aromatic
hydrocarbons.
[0088]
(Comparison Test Example 2)
The heavy fraction recovered after removing the catalyst using the catalyst
10 separator 14 in Comparison Test Example 1 and the heavy fraction having 10 or more
carbon atoms which had been derived from the third separation apparatus 22 and derived
in Example 2 were mixed. In addition, the heavy fraction mixture was provided to the
hydrogenation reactor 28 so as to cause a hydrogenation reaction, thereby obtaining a
hydrogenation reaction product of the heavy fraction mixture. After that, the obtained
15 hydrogenation reaction product was provided to the cracking and reforming reactor 10
instead of the feedstock oil, and a cracking and reforming reaction was allowed to
proceed. The mixing ratio (mass ratio) (Comparison Test Example 1 versus Example 2)
between the heavy fraction used in Comparison Test Example 1 and the heavy fraction
used in Example 2 was set to approximately 1 :9. Therefore, in the computation, the
20 amount (content rate) of tricyclic aromatic hydrocarbons in the heavy fraction mixture
became approximately 7.0% by mass.
[0089]
(Comparison Test Example 3)
LC0 having the same properties as in Comparison Test Example 1 and Example
25 2 was supplied to the cracking and reforming reactor 10 as a feedstock oil.
[0090]
In Comparison Test Example 1, Example 2, Comparison Test Example 2 and
Comparison Test Example 3, the BTX (benzene, toluene and xylene) in the respective
products obtained after causing the cracking and reforming reaction in the cracking and
5 reforming reactor 10, that is, the BTX yields were investigated. The results will be
described below. The units of the following BTX yields are % by mass.
[009 11
[Table 21
10 Here, (3RA) represents tricyclic aromatic hydrocarbons, and the numeric value
(3RA)
BTX yield
in parentheses represents the amount (content rate) of tricyclic aromatic hydrocarbons in
the heavy fraction before the hydrogenation reaction used in each of the examples.
[0092]
The results show that the BTX yield was far lower in Comparison Test Example
15 1 than in Comparison Test Example 3 even though the heavy fraction mainly containing
tricyclic aromatic hydrocarbon from which the catalyst had been removed using the
catalyst separator 14 was supplied to the cracking and reforming reactor 10 after a
Comparison
Test Example 1
(42.8)
26%
hydrogenation reaction. Therefore, it was found that it is not preferable to use the heavy
fraction from which the catalyst is removed using the catalyst separator 14 as a recycled
20 oil.
Example 2
(3.1)
48%
Comparison
Test Example 2
(7.0)
45%
In Example 2 in which the heavy fraction having 10 or more carbon atoms
which had been derived from the third separation apparatus 22 and recovered was
supplied to the cracking and reforming reactor 10 after the hydrogenation reaction and a
Comparison
Test Example 3
(4
37%
49
cracking and reforming reaction was carried out, the BTX yield sufficiently improved
comyared with Comparison Test Example 3. Furthermore, it was found that the BTX
yield sufficiently improves compared with Comparison Test Example 2. In Comparison
Test Example 2, the separated heavy fraction mainly containing tricyclic aromatic
5 hydrocarbons was mixed with the heavy fraction having 10 or more carbon atoms
derived from the third separation apparatus 22 and recovered, and the BTX yield was
higher in Example 2 than in Comparison Test Example 2, which indicated that the BTX
yield improves when the heavy fraction mainly containing tricyclic aromatic
hydrocarbons is removed.
10 Therefore, it was confirmed that, when tricyclic aromatic hydrocarbons were
removed using the catalyst separator 14 together with the catalyst, and the heavy fraction
having 10 or more carbon atoms derived from the third separation apparatus 22 and
recovered was provided to the cracking and reforming reaction step as a recycled oil
together with a feedstock oil, it was possible to improve the BTX yield compared with a
15 case in which only the feedstock oil was provided to the cracking and reforming reaction
step (Comparison Test Example 3).
INDUSTRIAL APPLICABILITY
[0093]
The invention is usehl for the production of monocyclic aromatic hydrocarbons
using LC0 obtained from an FCC apparatus and kerosene, a light oil or the like obtained
from a crude distillation apparatus as a raw material.
REFERENCE SIGNS LIST
5 0
CRACKING AND REFORMING REACTOR
CLEANING TOWER
CATALYST SEPARATION APPARATUS
FIRST SEPARATION APPARATUS
DEBUTANIZER (SECOND SEPARATION APPARATUS)
PURIFICATION AND RECOVERY APPARATUS
THIRD SEPARATION APPARATUS
FIRST RETURNING LINE
SECOND RETURNING LINE
HYDROGENATION REACTOR
HYDROGEN RECOVERY APPARATUS
RECYCLING LINE
HYDROGEN SUPPLY LINE
FRACTIONATOR

1. A method for producing monocyclic aromatic hydrocarbons in which
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms are produced fiom a
5 feedstock oil having a 10 volume percent distillation temperature of 140°C or higher and
a 90 volume percent distillation temperature of 380°C or lower, comprising:
a cracking and reforming reaction step of obtaining products containing
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms and a heavy fiaction
having 9 or more carbon atoms by bringing the feedstock oil into contact with a catalyst
10 for producing monocyclic aromatic hydrocarbons containing crystalline aluminosilicate
to cause a reaction;
a catalyst separation step of separating and removing the catalyst for producing
monocyclic aromatic hydrocarbons together with tricyclic aromatic hydrocarbons
contained in the products fiom a mixture of the products and a small amount of the
15 catalyst for producing monocyclic aromatic hydrocarbons carried by the products, both
of which are derived in the cracking and reforming reaction step; and
a purification and recovery step of purifying and recovering the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated from the products
formed in the cracking and reforming reaction step.
2. The method for producing monocyclic aromatic hydrocarbons according to
Claim 1,
wherein, in the catalyst separation step, a heavy fraction separated using a
separation step of separating the products formed in the cracking and reforming reaction
25 step into a plurality of fractions is brought into contact with the mixture of the products
and the catalyst for producing monocyclic aromatic hydrocarbons carried by the products,
both of which are derived in the cracking and reforming reaction step, thereby removing
the catalyst for producing monocyclic aromatic hydrocarbons from the mixture.
5 3. The method for producing monocyclic aromatic hydrocarbons according to
Claim 1 or 2,
wherein the heavy fraction separated using the separation step contains tricyclic
aromatic hydrocarbons as a main component.
4. A method for producing monocyclic aromatic hydrocarbons in which
monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms are produced from a
feedstock oil having a 10 volume percent distillation temperature of 140°C or higher and
a 90 volume percent distillation temperature of 380°C or lower, comprising:
a cracking and reforming reaction step of obtaining products containing
15 monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms and a heavy fraction
having 9 or more carbon atoms by bringing the feedstock oil into contact with a catalyst
for producing monocyclic aromatic hydrocarbons containing crystalline aluminosilicate
to cause a reaction;
a catalyst separation step of separating and removing the catalyst for producing
20 monocyclic aromatic hydrocarbons together with tricyclic aromatic hydrocarbons
contained in the products from a mixture of the products and the catalyst for producing
monocyclic aromatic hydrocarbons carried by the products, both of which are derived in
the cracking and reforming reaction step;
a separation step of separating at least the monocyclic aromatic hydrocarbons
25 having 6 to 8 carbon atoms and a heavy fraction having 9 or more carbon atoms from a
, .,-." t
! ' - r ; .
% a .--
YF
53 ' ' t "
derivative derived in the catalyst separation step;
a purification and recovery step of purifying and recovering the monocyclic
aromatic hydrocarbons having 6 to 8 carbon atoms which are separated in the separation
step; and
a recycling step of returning the heavy fraction having 9 or more carbon atoms
which is separated in the separation step to the cracking and reforming reaction step.
5. The method for producing monocyclic aromatic hydrocarbons according to
Claim 4, firther comprising:
a hydrogenation reaction step of hydrogenating the heavy fraction having 9 or
more carbon atoms which is separated in the separation step before the recycling step,
wherein, in the recycling step, a hydrogenation reaction product of the heavy
fraction having 9 or more carbon atoms obtained in the hydrogenation reaction step is
returned to the cracking and reforming reaction step.
6. The method for producing monocyclic aromatic hydrocarbons according to
Claim 5, further comprising:
a hydrogen recovery step of recovering hydrogen which is generated as a
by-product in the cracking and reforming reaction step from products obtained in the
cracking and reforming reaction step; and
a hydrogen supply step of supplying hydrogen recovered in the hydrogen
recovery step to the hydrogenation reaction step.
7. The method for producing monocyclic aromatic hydrocarbons according to
25 any one of Claims 4 to 6,
wherein the separation step includes a tricyclic aromatic hydrocarbon supply
,, I' step of supplying tricyclic aromatic hydrocarbons separated from the derivative which is
derived in the catalyst separation step to the catalyst separation step.
Dated this November 28,20 13
AT'TORNEY FOR THE APPLICANTS