The present invention relates to a method for producing monocyclic aromatic;
hydrocarbons that enables the production of monocyclic aromatic hydrocarbons from oils
containing a large amount of polycyclic aromatic hydrocarbons.
i0 Priority is claimed on Japanese Patent Application No. 2010-071743, filed
March 26, 2010, the content of which is incorporated herein by reference. i
BACKGROUND ART
5 [0002]
Light cycle oil (hereinafter also referred to as "LCO"), which is a cracked light
oil produced in a fluid catalytic cracker, contains a large amount of polycyclic aromatic
hydrocarbons, and has been used as a light oil or a heavy oil. However, in recent years,
investigations have been conducted into the possibilities of obtaining, from LCO,
10 monocyclic aromatic hydrocarbons (such as benzene, toluene, xylene and ethylbenzene),
which can be used as high-octane gasoline base stocks or petrochemical feedstocks, and
offer significant added value.
For example, Patent Documents 1 to 3 propose methods that use zeolite catalysts
to produce monocyclic aromatic hydrocarbons from the polycyclic aromatic
15 hydrocarbons contained in large amounts within LCO and the like.
25 CITATION LIST
2
PATENT DOCUMENTS
[0003]
[Patent Document I]
Japanese Unexamined Paten; Application, First Publication. No. H 3-2128
5 [Patent Document 2]
Japanese Unexamined Patent Application, First Publication No. H 3-52993
[Patent Document 3]
Japanese Unexamined Patent Application, first Publication "No. H 3-26791
'10 DISCLOSURE OF INVENTION
TECHNICAL PROBLEM
[0004]
However, in the methods discloses in Patent Documents 1 to 3, the yield of
monocyclic aromatic hydrocarbons of 6 to 8 carbon number cannot be claimed to be
5 5 entirely satisfactory.
The present invention has an object of providing a method for producing
monocyclic aromatic hydrocarbons that enables the production of monocyclic aromatic
hydrocarbons of 6 to 8 carbon number in a high yield from a feedstock oil containing
polycyclic aromatic hydrocarbons.
20
SOLUTION TO PROBLEM
[0005]
[ 1 ] A method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number from a feedstock oil having a 10 volume % distillation temperature of at least
23 i40°C and a 90 volume % distillation temperature of not more than 3S0°C, the method
including:
a cracking and reforming reaction step of bringing the feedstock oil into contact
with a monocyclic aromatic hydrocarbon production catalyst containing a crystalline
aluminosilicate, and reacting the feedstock, oil to obtain a product containing monocyclic
5 aromatic hydrocarbons of 6 to 8 carbon number,
a refining and collection step of refining and collecting monocyclic aromatic
hydrocarbons of 6 to 8 carbon number that have been separated from the product
obtained in the cracking and reforming reaction step,
a hydrogenation reaction step of hydrogenating a heavy fraction of 9 or more
10 carbon number separated from the product obtained in the cracking and reforming
reaction step, and
a recycling step of returning the heavy fraction hydrogenation reaction product
obtained in the hydrogenation reaction step to the cracking and reforming reaction step.
[2] The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
} 5 number according to [ 1 j , further including a feedstock oil mixing step of mixing a
portion of the feedstock oil with the heavy fraction of 9 or more carbon number separated
from the product obtained in the cracking and reforming reaction step,
13] A method for producing monocyclic aromatic hydrocarbons of 6 to S carbon
number from a feedstock oil having a 10 volume % distillation temperature of at least
20 140°C and a 90 volume % distillation temperature of not more than 380°C, the method
including:
a cracking and reforming reaction step of bringing the feedstock oil into contact
with a monocyclic aromatic hydrocarbon production catalyst containing a crystalline
aluminosilicate, and reacting the feedstock oil to obtain a product containing monocyclic
25 aromatic hydrocarbons of 6 to 8 carbon number,
ft
i 4
a hydrogenation reaction step of hydrogenating a portion of the product obtained
in the cracking and reforming reaction step,
a refining and collection step of refining and collecting monocyclic aromatic
hydrocarbons of 6 to 8 carbon number by distilling the hydrogenation reaction product
5 obtained in the hydrogenation reaction step, and
a recycling step of returning a heavy fraction of 9 or more carbon number, which
has been separated and removed from the monocyclic aromatic hydrocarbons of 6 to 8
carbon number in the refining and collection step, to the cracking and reforming reaction
step.
10 [4] The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number according to [3], further including a feedstock oil mixing step of mixing a
portion of the feedstock oil with a portion of the product obtained in the cracking and
reforming reaction step.
[5] A method for producing monocyclic aromatic hydrocarbon* of 6 to 8 carbon
! 5 number from a feedstock oil having a 10 volume % distillation temperature of at least
]4Q"C and a 90 volume % distillation temperature of not more than 38Q°C, the method
including:
a hydrogenation reaction step of hydrogenating the feedstock oil,
a cracking and reforming reaction step of bringing the hydrogenated product
20 obtained in the hydrogenation reaction step into contact with a monocyclic aromatic
hydrocarbon production catalyst containing a crystalline aluminosilioate. and reacting the
hydrogenated product to obtain a product containing monocyclic aromatic hydrocarbons
of 6 to 8 carbon number,
a refining and collection step of refining and collecting monocyclic aromatic
25 hydrocarbons of 6 to 8 carbon number that have been separated from the product
5
obtained in the cracking and reforming reaction step, and
a recycling step of returning a heavy fraction of 9 or more carbon number
separated from the product obtained in the cracking and reforming reaction step to the
hydrogenation reaction step.
5 [6] The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number according to any one of [I] to [5], wherein the crystalline aluminosilicate
contained within the monocyclic aromatic hydrocarbon production catalyst used in the
cracking and reforming reaction step contains a medium pore size zeolite and/or a large
pore size zeolite as a main component.
10 [7] The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number according to any one of [ 1] to [6], further including a hydrogen recovery step of
recovering, from the product obtained in the cracking and reforming reaction step, the
hydrogen that is produced as a byproduct in the cracking and reforming reaction step,
and a hydrogen supply step of supplying the hydrogen recovered in the hydrogen
15 recovery step to the hydrogenation reaction step.
ADVANTAGEOUS EFFECTS OF INVENTION
[0006]
The monocyclic aromatic hydrocarbon production catalyst and the method for
20 producing monocyclic aromatic hydrocarbons of 6 to 8 carbon number according to the
present invention enable the production of monocyclic aromatic hydrocarbons of 6 to 8
carbon number in a high yield from a feedstock oil containing polycyclic aromatic
hydrocarbons,
15 BRIEF DESCRIPTION OF THE DRAWINGS
6
[0007]
FIG. 1 is a diagram describing a first embodiment of the method for producing
monocyclic aromatic hydrocarbons according to the present invention.
FIG. 2 is a diagram describing a second embodiment of the method for
5 producing monocyclic aromatic hydrocarbons according to the present invention.
FIG. 3 is a diagram describing a third embodiment of the method for producing
monocyclic aromatic hydrocarbons according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
10 [0008]
[First. Embodiment]
A first embodiment of the method for producing monocyclic aromatic
hydrocarbons according to the present invention is described below.
The method for producing monocyclic aromatic hydrocarbons according to this
15 embodiment is a method for producing monocyclic aromatic hydrocarbons of 6 to 8
carbon number (hereinafter referred to as simply "monocyclic aromatic hydrocarbons")
from a feedstock oil that represents an embodiment of aspect [1] of the present invention,
and includes the steps (a) to (i) described below (see FIG 1),
(a) A cracking and reforming reaction step of bringing a feedstock oil into contact
20 with a monocyclic aromatic hydrocarbon production catalyst, and reacting the feedstock
oil to obtain a product containing monocyclic aromatic hydrocarbons.
(b) A separation step of separating the product obtained in the cracking and
reforming reaction step into a plurality effractions.
(c) A refining and collection step of refining and collecting the monocyclic aromatic
25 hydrocarbons separated in the separation step.
i 7 :
(d) A heavy fraction discharge step of discharging outside the system a portion of
the heavy fraction of 9 or more carbon number (hereinafter referred to as simply the
"heavy fraction") obtained from a fraction separated in the separation step,
(e) A feedstock oil mixing step of mixing a portion of the feedstock oil with the
5 heavy fraction that was not discharged outside the system in the heavy fraction discharge
step.
(f) A hydrogenation reaction step of hydrogenating the heavy fraction that was not
discharged outside the system in the heavy fraction discharge step, or the mixed oil
obtained by mixing the heavy fraction with a portion of the feedstock oil'
10 (g) A hydrogen recovery step of recovering, from the gas component separated in
the separation step, the hydrogen produced as a byproduct in the cracking and reforming
reaction step.
(h) A hydrogen supply step of supplying the hydrogen recovered in the hydrogen
recovery step to the hydrogenation reaction step,
15 (i) A recycling step of returning a heavy fraction hydrogenation reaction product
obtained in the hydrogenation reaction step to the cracking and reforming reaction step.
Of the steps (a) to (i) described above, the steps (a), (c), (f) and (i) are essential
steps in the method according to the first embodiment, whereas the steps (b), (d), (e), (g)
and (h) are optional steps.
20 Each of the above steps is described below in further detail.
[0009]

The feedstock oil contains polycyclic aromatic hydrocarbons and saturated
hydrocarbons
25 In the cracking and reforming reaction step, the feedstock oil is brought into
4
I 8
contact with the monocyclic aromatic hydrocarbon production catalyst, tnd with the
saturated hydrocarbons contained within the feedstock oil functioning as hydrogen donor
sources, a hydrogen transfer reaction from the saturated hydrocarbons is used to partially
hydrogenate the polycyclic aromatic hydrocarbons, thereby effecting ring-opening and
5 converting the polycyclic aromatic hydrocarbons into monocyclic aromatic hydrocarbons,
Further, monocyclic aromatic hydrocarbons are also formed by cyclization and
dehydrogenation of saturated hydrocarbons, which either exist within the feedstock oil or
are formed by a cracking process, Moreover, monocyclic aromatic hydrocarbons of 6 to
8 carbon number can also be obtained by cracking of monocyclic aromatic hydrocarbons
10 of 9 or more carbon number. In addition to the monocyclic aromatic hydrocarbons, the
product of the cracking and reforming reaction also includes hydrogen, methane, LPQ
and a heavy fraction of 9 or more carbon number and the like,
[0010]
(Feedstock oil)
15 The feedstock oil used in the present invention is an oil having a 10 volume %
distillation temperature of at least 140°C and a 90 volume % distillation temperature of
not more than 380°C. With an oil having a 10 volume % distillation temperature of less
than 140°C, the reaction involves production of monocyclic- aromatic hydrocarbons from
light compounds, which is outside the scope of the present invention, Further, if an oil
20 having a 90 volume % distillation temperature that exceeds 380°C is used, then the yield
of monocyclic aromatic hydrocarbons tends to decrease, and the amount of coke
deposition on the monocyclic aromatic hydrocarbon production catalyst tends to increase,
causing a more rapid deterioration in the catalytic activity.
The 10 volume % distillation temperature of the feedstock oil is preferably
25 1 SO'C or higher, and the 90 volume % distillation temperature of the feedstock, oil is
: 9
preferably not more than 360°C.
In this description, the 10 volume % distillation temperature and the 90
volume % distillation temperature refer to values measured in accordance with the
methods prescribed in JIS K 2254 "Petroleum products - determination of distillation
5 characteristics".
Examples of feedstock oils having a 10 volume % distillation temperature of at
least I40°C and a 90 volume % distillation temperature of not more than 38Q°C include
cracked light oils (LCO) produced in a fluid catalytic cracker, hydrotreated LCO, coal
Liquefaction oil, hydrocracked oil from heavy oils, straight-run kerosene, straight-run gas
I 10 oil. coker kerosene, coker gas oil, and hydrocracked oil from oil sands.
Polycyclic aromatic hydrocarbons exhibit low reactivity and are difficult to
convert to monocyclic aromatic hydrocarbons in the cracking and reforming reaction step
of the present invention. However, these polycyclic aromatic hydrocarbons are
hydrogenated in the hydrogenation reaction step and converted to naphthenobenzenes,
15 and if these naphthenobenzenes are then recycled and re-supplied to the cracking and
reforming reaction step, they can be converted to monocyclic aromatic hydrocarbons.
Accordingly, there are no particular limitations in terms of the feedstock oil containing a
large amount of polycyclic aromatic hydrocarbons. However, among polycyclic
aromatic hydrocarbons, tricyclic and higher aromatic hydrocarbons consume a large
20 amount of hydrogen in the hydrogenation reaction step, and suffer from poor reactivity in
the cracking and reforming reaction step even in the form of a hydrogenation reaction
product, and therefore the feedstock oil preferably does not contain a large amount of
such tricyclic and higher aromatic hydrocarbons. Accordingly, the amount of tricyclic
and higher aromatic hydrocarbons within the feedstock oil is preferably not more than 25
25 volume %, and more preferably 15 volume % or less.
4
J 10
Examples of particularly desirable feedstock: oils which contain bieyclic
aromatic hydrocarbons that can be readily converted to naphthenoberizenes in the
hydrogenation reaction step, but in which the amount of tricyclic or higher aromatic
I hydrocarbons is reduced, include feedstock oils having a 90 volume % distillation
5 temperature of not more than 33 0°C.
In this description, the polycyciic aromatic fraction describes the combined total
of the amount of bieyclic aromatic hydrocarbons (the bieyclic aromatic fraction) and the
amount of tricyclic and higher aromatic hydrocarbons (the tricyclic and higher aromatic
fraction), which is either measured in accordance with JPI-5S-49 "Petroleum Products
10 -Determination ofHydrocarbon Types-ffigh Performance Liquid Chromatography", or
determined by analysis using FID gas chromatography or two-dimensional gas
chromatography. In the following description, an amount of polycyciic aromatic
hydrocarbons, bieyclic aromatic hydrocarbons or tricyclic or higher aromatic
hydrocarbons reported using the units "volume %" represents an amount that has been
15 measured in accordance with JPI-5 S-49, whereas an amount that is reported using the
units"% by mass" represents an amount that has been measured on the basis of FID gas
chromatography or two-dimensional gas chromatography.
[0011]
(Reaction format)
20 Examples of the reaction format used for biinging the feedstock oil into contact
with the monocyclic aromatic hydrocarbon production catalyst include fixed beds,
moving beds and fluidized beds. In the present invention, because a heavy oil fraction
is used as the feedstock, a fluidized bed is preferred as it enables the coke fraction
adhered to the catalyst to be removed in a continuous manner and enables the reaction to
25 proceed in a stable manner. A continuous regeneration-type fluidized bed, in which the
4
catalyst is circulated between the reactor and a regenerator, thereby continuously
repeating a reaction-regeneration cycle, is particularly desirable, The feedstock oil is
preferably in a gaseous state when it makes contact with the monocyclic aromatic
hydrocarbon production catalyst. Further, the feedstock may be diluted with a gas if
5 required.
[0012]
(Monocyclic Aromatic Hydrocarbon Production Catalyst)
The monocyclic aromatic hydrocarbon production catalyst contains a crystalline
aluminosilicate.
30 [0013]
[Crystalline Aluminosilicate]
The crystalline aluminosilicate is preferably a medium pore size zeolite and/or a
large pore size zeolite, as these materials enable the yield of the monocyclic aromatic
hydrocarbons to be further increased.
15 Medium pore size zeolites are zeolites having a 10-membered ring basic
structure, and examples of these medium pore size zeolites include zeolites having AEL,
EUO, FER, HEU, MEL, MFI, NES, TON and WEI type crystal structures. Among
these, MH-type zeolites are preferred as they enable a greater increase in the yield of
monocyclic aromatic hydrocarbons.
20 Large pore size zeolites are zeolites having a 12-membered ring basic structure,
and examples of these large pore size zeolites include zeolites having AFI, ATO, BEA,
CON, FAU, GME, LTL, MOR, MTW and OFF type crystal structures. Among these,
BEA, FAU and MOR type zeolites are preferred in terms of industrial usability, and
BEA-type zeolites are particularly desirable as they enable a greater increase in the yield
25 of monocyclic aromatic hydrocarbons.
12
[0014]
Besides the above medium pore size zeolites and large pore size zeolites, the
crystalline aluminosilicate may also contain small pore size zeolites having a
IQ-membered ring or smaller basic structure, and extra large pore size zeolites having a
5 14-membered ring or larger basic structure,
Examples of the small pore size zeolites include zeolites having ANA, CHA,
j ERI, GIS, KFI, LTA, NAT, PAU and YUG type crystal structures,
Examples of the extra large pore size zeolites include zeolites having CLO and
VPI type crystal structures.
| 10 [0015]
In those cases where the cracking and reforming reaction step is conducted as a.
fixed bed reaction, the amount of the crystalline aluminosilicate within the monocyclic
aromatic hydrocarbon production catalyst, relative to a value of 100% by mass for the
entire catalyst, is preferably within a range from 60 to 100% by mass, more preferably
15 from 70 to 100% by mass, and still more preferably from 90 to 100% by mass.
Provided the amount of the crystalline aluminosilicate is at least 60% by mass, the yield
of monocyclic aromatic hydrocarbons can be increased satisfactorily.
In those cases where the cracking and reforming reaction step is conducted as a
fluidized bed reaction, the amount of the crystalline aluminosilicate within the
20 monocyclic aromatic hydrocarbon production catalyst, relative to a value of 100% by
mass for the entire catalyst, is preferably within a range from 20 to 60% by mass, more
preferably from 30 to 60% by mass, and still more preferably from 35 to 60% by mass.
Provided the amount of the crystalline aluminosilicate is at least 20% by mass, the yield
of monocyclic aromatic hydrocarbons can be increased satisfactorily. However, if the
25 amount of the crystalline aluminosilicate exceeds 60% by mass, then the amount of
13
binder that can be included in the catalyst decreases, and the resulting catalyst may be
unsuitable for a fluidized bed.
[0016]
[Phosphorus, Boron]
5 The monocyclic aromatic hydrocarbon production catalyst preferably also
includes phosphorus and/or boron. If the monocyclic aromatic hydrocarbon production
catalyst includes phosphorus and/or boron, then a deterioration over time in the yield of
monocyclic aromatic hydrocarbons can be prevented, and coke production on the catalyst
surface can be inhibited.
10 [0017]
Examples of methods for incorporating phosphorus within the monocyclic
aromatic hydrocarbon production catalyst include ion-exchange methods and
, impregnation methods. Specific examples include methods in which phosphorus is
supported on a crystalline aluminosilicate, crystalline alumtnogallosilicate or crystalline
15 aluminozincosilicate, methods in which a phosphorus compound is added during
synthesis of the zeolite, thereby substituting a portion of the internal framework of the
crystalline aluminosilicate with phosphorus, and methods in which a crystallization
promoter containing phosphorus is used during synthesis of the zeolite. Although there
are no particular limitations on the phosphate ion-containing aqueous solution used in the
20 above methods, a solution prepared by dissolving phosphoric acid, diammonium
hydrogen phosphate, ammonium dihydrogen phosphate or another water-soluble
phosphate salt or the like in water at an arbitrary concentration can be used particularly
favorably.
Examples of methods for incorporating boron within the monocyclic aromatic
25 hydrocarbon production catalyst include ion-exchange methods and impregnation
i 14 l
I ^ methods. Specific examples include methods in which boron is supported on a
1 crystalline aiuminosilicate, crystalline aluminogallosilicate or crystalline
alumtnozincosilicate, methods in which a boron compound is added during synthesis of
the zeolite, thereby substituting a portion of the internal framework of the crystalline
5 aiuminosilicate with boron, and methods in which a crystallization promoter containing
boron is used during synthesis of the zeolite.
i [ooi 8]
The amount of phosphorus and/or boron included in the monocyclic aromatic
{ hydrocarbon production catalyst, relative to the total mass of the catalyst, is preferably
1 10 within a range from 0,1 to 10% by mass, wherein the lower limit is more preferably not
less than 0.5% by mass, and the upper limit is more preferably not more than 9% by mass,
j and still more preferably not more than 8% by mass. Provided the amoum of
i phosphorus relative to the total mass of the catalyst is at least 0.1% by mass, any
deterioration over time in the yield of the monocyclic aromatic hydrocarbons can be
; 3 5 prevented, and provided the amount of phosphorus is not more than 10% by mass, the
I yield of the monocyclic aromatic hydrocarbons can be increased,
[0019]
[Gallium, Zinc]
If necessary, gallium and/or zinc may be included in the monocyclic aromatic
20 hydrocarbon production catalyst. Including gallium and/or zinc can improve the rate of
production of monocyclic aromatic hydrocarbons.
[0020]
Examples of the form of the gallium contained within the monocyclic aromatic
hydrocarbon production catalyst include catalysts in which the gallium is incorporated
25 within the lattice framework of the crystalline aiuminosilicate (crystalline
•: 15
aluminogallosilicates), catalysts in which gallium is supported on the crystalline
aluminosilicate (gallium-supporting crystalline aluminosilicates), and catalysts including
both of these forms.
Examples of the form of the zinc contained within the monocyclic aromatic
5 hydrocarbon production catalyst include catalysts in which the zinc is incorporated
within the lattice framework of the crystalline aluminosilicate (crystalline
aluminozincositicates), catalysts in which zinc is supported on the crystalline
aluminosilicate (zinc-supporting crystalline aluminosilicates), and catalysts including
both of these forms.
10 A crystalline aluminogallosilicate or a crystalline aluminozincosilicate has a
structure in which Si&t, AIO4., and Ga04 or ZnO* structures exist within the framework.
A crystalline alurainogallosilicate or crystalline aluminozincosilicate cart be obtained, for
example, by gel crystallization via hydrothermal synthesis, or by a method in which
gallium or zinc respectively is inserted into the lattice framework of a crystalline
15 aluminosilicate. Further, a crystalline aluminogallosilicate or crystalline
aluminozincosilicate can also be obtained by a method in which aluminum is inserted
into the lattice framework of a crystalline gallosilicate or crystalline zincosilicate
respectively.
A gallium-supporting crystalline aluminosilicate can be obtained by supporting
20 gallium on a crystalline aluminosilicate using a conventional method such as an
ion-exchange method or impregnation method. There are no particular limitations on
the gallium source used in these methods, and examples include gallium salts such as
gallium nitrate and gallium chloride, and gallium oxide.
A zinc-supporting crystalline aluminosilicate can be obtained by supporting zinc
25 on a crystalline aluminosilicate using a conventional method such as an ion-exchange
method or impregnation method. There are no particular limitations on the zinc source
; used in these methods, and examples include zinc salts such as zinc nitrate.and zinc
chloride, and sine oxide.
I [0021]
5 In those cases where the monocyclic aromatic hydrocarbon production catalyst
contains gallium and/or zinc, the amount of gallium and/or zinc within the monocyclic
aromatic hydrocarbon production catalyst, relative to a value of 100% for the total mass
of the catalyst, is preferably within a range from 0.01 to 5.0% by mass, and more
preferably from 0.05 to 2.0% by mass, Provided the amount of gallium and/or zinc is at
10 least 0.01% by mass, the rate of production of monocyclic aromatic hydrocarbons can be
increased, and provided the amount is not more than 5.0% by mass, the yield of
monocyclic aromatic hydrocarbons can be improved,
[0022]
[Form]
15 The monocyclic aromatic hydrocarbon production catalyst is used in the form of
a powder, granules or pellets or the like, depending on the reaction format. For example,
a powder is used in the case of a fluidized bed, whereas granules or pellets are used in the
case of a fixed bed. The average particle size of the catalyst used in a fluidized bed is
preferably within a range from 30 to 180 urn, and more preferably from 50 to 100 jam
20 Further, the untamped density of the catalyst used in a fluidized bed is preferably within a
range from 0.4 to 1.8 g/cc, and more preferably from 0.5 to 1.0 g/cc.
The average particle size describes the particle size at which the particle size
distribution obtained by classification using sieves reaches 50% by mass, whereas the
untamped density refers to the value measured using the method prescribed in US R
25 9301-2-3.
In order to obtain a catalyst in granular or pellet form, if necessary, an inert
oxide may be added to the catalyst as a binder, with the resulting mixture then molded
using any of various molding apparatus,
[0023J
5 In those cases where the monocyclic aromatic hydrocarbon production catalyst
contains an inorganic oxide such as a binder. 3. compound that contains phosphorus may
be used as the binder.
[0024]
(Reaction Temperature)
10 Although there are no particular limitations on the reaction temperature during
contact of the feedstock oil with the monocyclic aromatic hydrocarbon production
catalyst and subsequent reaction, a reaction temperature of 400 to 650°C is preferred
Provided the lower limit for the reaction temperature is at least 400CC, the feedstock oil
can be reacted with relative ease. The lower limit is more preferably 450°C or higher.
15 On the other hand, provided the upper limit temperature is not more than 650°C, the
yield of monocyclic aromatic hydrocarbons can be increased. The upper limit is more
preferably 600°C or lower.
[00251
(Reaction Pressure)
20 The reaction pressure during contact of the feedstock oil with the monocyclic
aromatic hydrocarbon production catalyst and subsequent reaction is preferably not more
than 1.5 MPaG; and more preferably 1.0 MPaG or less. Provided the reaction pressure
is not more than 1.5 MPaG; the generation of by-product light gases can be prevented,
and the pressure resistance required for the reaction apparatus can be lowered.
25 [0026]
i 18
(Contact Time)
There are no particular limitations on the contact time between the feedstock oil
and the monocyclic aromatic hydrocarbon production catalyst, provided the desired
reaction proceeds satisfactorily, but in terms of the gas transit time across the monocyclic
5 aromatic hydrocarbon production catalyst, a time of 1 to 300 seconds is preferred, The
lower limit for this time is more preferably at least 5 seconds, and the upper limit is more
preferably 150 seconds or less. Provided the contact time is at least 1 second, a reliable
reaction can be achieved, whereas provided the contact time is not more than 300
seconds, deposition of carbon matter on the catalyst due to coking or the like can be
10 suppressed. Further, the amount of light gas generated by cracking can also be
suppressed.
[0027]
<5eparation Step>
In the separation step, the product obtained in the cracking and reforming
15 reaction step is separated into a plurality of fractions.
In order to achieve this separation into a plurality of fractions, a conventional
distillation device or gas-liquid separation device may be used. One example of a
distillation device is a device such as a stripper which employs a multi-stage distillation
device to achieve separation by distillation into a plurality effractions. One example of
20 a gas-liquid separation device is a device containing a gas-liquid separation tank, a
product inlet line through which the product is introduced into the gas-liquid separation
tank, a gas component discharge line provided in the upper section of the gas-liquid
separation tank, and a liquid component discharge line provided in the lower section of
the gas-liquid separation tank.
25 In the separation step, it is preferable that at least the gas components and the
19
liquid fraction are separated, and the liquid fraction may be further separated into a
plurality of fractions. In one example of the separation step, the product is separated
into a gas component containing mainly components of 4 or fewer carbon number (such
as hydrogen, methane, ethane and IJPG) and a liquid fraction, In an alternative
5 separation step, the product may be separated into a gas component containing
components of 2 or fewer carbon number (such as hydrogen, methane and ethane) and a
liquid fraction. In yet another example of the separation step, the above liquid fraction
may be separated into LPG, a fraction containing monocyclic aromatic hydrocarbons, and
a heavy fraction. Further, in yet another example of the separation step, the above
10 liquid fraction may be separated into LPG, a fraction containing monocyclic aromatic
hydrocarbons, and a plurality of heavy fractions. Moreover, in those cases where a
fluidized bed is used as the reaction format for the cracking and reforming reaction step,
the catalyst powder and the like incorporated within the product may also be removed in
the separation step.
15 [0028]

The refining and collection step is used for refining and collecting the
monocyclic aromatic hydrocarbons obtained in the separation step,
In those cases where the liquid fraction has not undergone fractional distillation
20 in the separation step, the refining and collection step may employ a process of
separating and removing the fraction heavier than the monocyclic aromatic hydrocarbons,
and collecting the monocyclic aromatic hydrocarbons, or benzene/toluene/xylene. In
those cases where the fraction heavier than the monocyclic aromatic hydrocarbons has
been separated in the separation step, the refining and collection step may employ a
25 process of collecting the benzene/toluene/xylene, The fraction heavier than the
20
monocyclic aromatic hydrocarbons refers to the heavy fraction of 9 or more carbon
number, which contains mainly polycyclic aromatic hydrocarbons, and in particular,
contains large amounts of naphthalene and alkylnaphthalertes.
[0029]
5
In the heavy fraction discharge step, a fixed portion of the heavy fraction of 9 or
more carbon number obtained by separation by fractional distillation in the separation
step is extracted and discharged outside the system. If the heavy fraction discharge step
is not provided, then as the amount of recycling increases, the amount of low-reactivity
10 components within the heavy fraction increases, but in the present embodiment, because
a fixed portion of the heavy fraction is discharged in the heavy fraction discharge step,
any increase in the amount of low-reactivity components within the heavy fraction can be
suppressed. As a result, any deterioration over time in the yield of mono cyclic aromatic
hydrocarbons can be prevented,
15 The amount of the heavy fraction discharged outside the system is preferably not
more than 90% by mass of the heavy fraction, more preferably not more .than 50% by
mass, and still more preferably 20% by mass or less. Provided the amount of the heavy'
fraction discharged outside the system is not more than 90% by mass of the heavy
fraction, satisfactory recycling can be achieved, and the yield of monocyclic aromatic
20 hydrocarbons can be increased. Although there are no particular limitations on the
lower limit for the amount of the heavy fraction discharged outside the system, an
amount of at least 0.5% by mass is preferable.
The heavier hydrocarbons within the heavy fraction are preferably extracted as
the heavy fraction for discharge outside the system, For example, even if a fraction
25 containing a large amount of tricyclic aromatic hydrocarbons is recycled, conversion to
21 }
monocyclic aromatic hydrocarbons is comparatively difficult compared with other
fractions, and therefore by discharging this fraction outside the system, any deterioration
over time in the yield of the monocyclic aromatic hydrocarbons can be prevented. The
heavy fraction discharged outside the system can be used as a flic! base stock or the like. 5 [0030]

In the feedstock oil mixing step, a portion of the feedstock oil for the cracking
and reforming reaction step is mixed with the heavy fraction that was not discharged
outside the system in the heavy fraction discharge step. By mixing a portion of the
10 feedstock oil with the heavy fraction that was not discharged outside the system in the
heavy fraction discharge step, the concentration of polycyclic aromatic hydrocarbons within the mixed oil supplied to the subsequent hydrogenation reaction step can be
reduced to a level lower than the concentration of polycyclic aromatic hydrocarbons
within the heavy fraction. By reducing the concentration of polycyclic aromatic
15 hydrocarbons in this manner, the amount of heat generated in the hydrogenation reaction ;
step can be suppressed, enabling a milder hydrogenation treatment, and the amounts of
naphthenobenzenes within the hydrogenation reaction product can be increased. By
supplying and recycling the hydrogenation reaction product obtained in this manner to
the cracking and reforming reaction step, the yield of monocyclic aromatic hydrocarbons
20 can be increased.
[0031]

In the hydrogenation reaction step, the heavy fraction that was not discharged
outside the system in the heavy fraction discharge step, or the mixed oil obtained in the
25 feedstock oil mixing step by mixing the heavy fraction with a portion'of the feedstock oil '
22
for the cracking and reforming reaction step (hereinafter, both cases are referred to using
the term "heavy fraction"), is subjected to hydrogenation. Specifically, the heavyfraction
and hydrogen are supplied to a hydrogenation reactor, and a hydrogenation
catalyst is used to hydrotreat at least a portion of the polycyclic aromatic hydrocarbons
5 contained within the heavy fraction.
The hydrogenation is preferably continued until the polycyclic aromatic
hydrocarbons are converted to compounds having an average number of aromatic rings
of one or less. For example, the hydrogenation is preferably performed until
naphthalene is converted to tetralin (naphthenobenzene). If the hydrogenation is
10 performed until the average number of aromatic rings is one or less, then the resulting
product can be more readily converted to monocyclic aromatic hydrocarbons when
returned to the cracking and reforming reaction step.
Further, in order to enable an additional increase in the yield of monocyclic
aromatic hydrocarbons, the hydrogenation reaction step is preferably performed such that
15 the amount of polycyclic aromatic hydrocarbons within the resulting hydrogenation
reaction product of the heavy fraction is not more than 40% by mass, more preferably not
more than 25% by mass, and still more preferably not more than 15% by mass. The
amount of polycyclic aromatic hydrocarbons within the hydrogenation reaction product
obtained upon completion of the hydrogenation reaction step is preferably lower than the
20 polycyclic aromatic hydrocarbon content of the feedstock oil. The amount of
polycyclic aromatic hydrocarbons within the hydrogenation reaction product can be
reduced by increasing the amount of the hydrogenation catalyst and/or increasing the
hydrogenation reaction pressure. However, there is no need to continue the
hydrogenation reaction until all of the polycyclic aromatic hydrocarbons have been
25 converted to saturated hydrocarbons. Excessive hydrogenation tends to result in
23"
increased hydrogen consumption and increased heat generation.
[0032]
In the present embodiment, the hydrogen produced as a by-product in the
cracking and reforming reaction step can be used as the hydrogen for the hydrogenation
5 reaction step. In other words, hydrogen can be collected from the gas component
obtained in the separation step in the hydrogen collection step described below, and the
collected hydrogen can then be supplied to the hydrogenation reaction step in the
hydrogen supply step.
[0033]
10 A fixed bed can be used favorably as the reaction format for the hydrogenation
reaction step.
\ Conventional hydrogenation catalysts may be used as the hydrogenation catalyst,
including nickel catalysts, palladium catalysts, nickel-molybdenum catalysts,
cobah-molybdenum catalysts, nickel-eobatt-molybdenum catalysts and nickel-tungsten
15 catalysts,
The hydrogenation reaction temperature varies depending on the hydrogenation
catalyst used, but is typically within a range from 100 to 450,:]C, preferably from 200 to
400°C, and more preferably from 250 to 380°C.
The hydrogenation reaction pressure varies depending on the hydrogenation
20 catalyst used and the nature of the feedstock, but is preferably within a range from 0,7
MPa to 13 MPa, more preferably from 1 MPa to 10 MP a, and still more preferably from
1 MPa to 7 MPa. Provided the hydrogenation reaction pressure is not more than 13 MPa,
a hydrogenation reactor with minimal pressure resistance can be used, thereby reducing
equipment costs.
25 On the other hand, in terms of the yield of the hydrogenation reaction... the
I i
• 24
hydrogenation reaction pressure is preferably at least 0,7 MPa.
{ The amount of hydrogen consumed is preferably not more than 3,000 scfb (506
' NmVm3), more preferably not more than 2,500 scfb (422 Nm2/m5), and still more
j preferably 1,500 scfb (253 Nm7m3) or less.
! 5 On the other hand, in terms of the yield of the hydrogenation reaction, the
amount of hydrogen consumed is preferably at least 300 scfb (50 Nnv/rn3),
| The liquid hourly space velocity (LHSV) is preferably within a range from 0,1
j h"! to 20 h'1, and more preferably from 0.2 h"1 to 10 h4, Provided the LHSV is not more
than 20 h"1, the polycyclic aromatic hydrocarbons can be satisfactorily hydrogenated at a
10 lower hydrogenation reaction pressure. In contrast, ensuring that the LHSV is at least
'< 0.1 h'1 avoids the need to increase the size of the hydrogenation reactor.
I [0034] '

In the hydrogen recovery step, hydrogen is recovered from the gas component
15 obtained in the separation step.
There are no particular limitations on the method used for recovering the
hydrogen, provided it enables the hydrogen contained within the gas component obtained
in the separation step to be separated from the other gases within the gas component, and
examples include the pressure swing adsorption method (PSA method), cryogenic
20 separation methods, and membrane separation methods.
Typically, the amount of hydrogen recovered in the hydrogen recovery step is
larger than the amount of hydrogen required to hydrogenate the heavy fraction.
fQ035]

25 In the hydrogen supply step, the hydrogen obtained in the hydrogen recovery
4
25
step is supplied to the hydrogenation reactor used in the hydrogenation reaction step.
The amount of hydrogen supplied is adjusted in accordance with the amount of the heavyfraction
supplied to the hydrogenation reaction step. Further, the hydrogen pressure
may also be altered as required.
3 If a hydrogen supply step is provided as in the present embodiment, then the
hydrogen produced as a by-product in the preceding cracking and reforming reaction step
can be used for hydrogenating the heavy fraction. By supplying some or all of the
hydrogen used in the method for producing monocyclic aromatic hydrocarbons according
to the present invention from by-product hydrogen, supply of hydrogen from an external
3 0 source can be partially or completely eliminated.
[0036]

In the recycling step, the heavy fraction hydrogenation reaction product obtained
in the hydrogenation reaction step is mixed with the feedstock oil and returned to the
15 cracking and reforming reaction step.
By returning the heavy fraction hydrogenation reaction product obtained by
hydrotreating the heavy fraction to the cracking and reforming reaction step, the heavy
fraction that represents a by-product can be used as a feedstock for producing monocyclic
aromatic hydrocarbons. As a result, the amount of by-products can be reduced, and the
20 production of monocyclic aromatic hydrocarbons can be increased. Further, because
saturated hydrocarbons are also produced in the hydrogenation reaction step, hydrogen
transfer reactions in the cracking and reforming reaction step can be accelerated. For
these reasons, the overall yield of monocyclic aromatic hydrocarbons relative to the
amount of feedstock oil supplied can be increased.
25 If the heavy fraction is simply returned to the cracking and reforming reaction
4
26
step without, first undergoing hydrotreatmeiu, then because the reactivity of the
polycyclic aromatic hydrocarbons is low, there is almost no improvement in the yield of
monocyclic aromatic hydrocarbons. (
[0037] I
5 {Second Embodiment] I
A second embodiment of the method, for producing monocyclic aromatic j
hydrocarbons according to the present invention is described below.
The method for producing monocyclic aromatic hydrocarbons according to this ;
embodiment is a method for producing monocyclic aromatic hydrocarbons from a
10 feedstock oil that represents an embodiment of aspect [3] of the present invention, and
includes the steps (j) to (r) described below (see FIG 2),
(j) A cracking and reforming reaction step of bringing a feedstock oil into contact I
with a monocyclic aromatic hydrocarbon production catalyst, and reacting the feedstock
oil to obtain a product containing monocyclic aromatic hydrocarbons.
15 (k) A separation step of separating the product obtained in the cracking and
reforming reaction step into a gas component and a liquid component.
(1) A feedstock oil mixing step of mixing a portion of the feedstock oil with a
portion of the liquid fraction separated in the separation step. (m) A hydrogenation reaction step of hydrogenating a portion of the liquid fraction
20 separated in the separation step, or the mixed oil prepared by mixing the liquid fraction j
and a portion of the feedstock oil.
(n) A hydrogen recovery step of recovering, from the gas component separated in
the separation step, the hydrogen produced as a byproduct in the cracking and reforming i
reaction step, I
25 (o) A hydrogen supply step of supplying the hydrogen recovered in the hydrogen
i
recovery step to the hydrogenation reaction step.
(p) A refining and collection step of refining and collecting monocyclic aromatic
hydrocarbons by distilling the hydrogenation reaction product obtained in the
hydrogenation reaction step.
5 (q) A heavy fraction discharge step of discharging outside the system a portion of
the heavy fraction obtained by separation from the monocyclic aromatic hydrocarbons in
the refining and collection step.
(r) A recycling step of returning, to the cracking and reforming reaction step, the
heavy fraction that was not discharged outside the system in the heavy fraction discharge !
10 step.
Of the steps (j) to (r) described above, the steps (j), (m), (p) and (r) are essential
steps in the method according to the second embodiment, whereas the steps (k), (I), (n),
(o) and (q) are optional steps. j
[0038] j
15 The cracking and reforming reaction step (j) may be performed in the same |
manner as the cracking and reforming reaction step (a) in the first embodiment. The separation step (k) may be performed in the same manner as the separation j
step (b) in the first embodiment. For example, a separation may be performed in which the product is separated into a gas component containing components of 4 or fewer «
20 carbon number (such as hydrogen, methane, ethane and LPG) and a liquid fraction, The |
liquid fraction undergoes separation in the refining and collection step (p), and therefore unlike the first embodiment, separation of the liquid fraction into a fraction containing monocyclic aromatic hydrocarbons and a heavy fraction need not be performed at this j
point. However, an extremely heavy fraction that is unsuitable for the recycling that f
25 represents the object of the present invention, and/or a catdyst powder that is }
I
i
28 [
incorporated within the product in those cases where a fiuidized bed is employed in the
cracking and reforming reaction step may be removed as required. However, even in i
such cases, the monocyclic aromatic hydrocarbons and the heavy fraction that is to
undergo hydrogenation and recycling are not separated at this point.
5 The feedstock oil mixing step (1) may be performed in the same manner as the
feedstock oil mixing step (e) of the first embodiment, with the exception that the liquid
component obtained in the separation step (k) is used for mixing with the feedstock oil
Instead of the heavy fraction that was not discharged outside the system that was used in
the feedstock oil mixing step (e).
10 The hydrogen recovery step (n) may be performed in the same manner as the
hydrogen recovery step (g) of the first embodiment.
The hydrogen supply step (o) may be performed in the same manner as the
hydrogen supply step (h) of the first embodiment.
i {0039]
15 The hydrogenation reaction step (m) of the present embodiment may use the
same hydrogenation catalyst as that used in the hydrogenation reaction step (f) of the first
embodiment.
In the hydrogenation reaction step (m), unlike the hydrogenation reaction step
(f) of the first embodiment, the entire liquid component obtained in the separation step,
20 or the mixed oil obtained in the feedstock oil mixing step (1) by mixing the liquid
component obtained in the separation step with a portion of the feedstock oil for the
cracking and reforming reaction step, is fed through the hydrogenation reactor, and
therefore the obtained monocyclic aromatic hydrocarbons are also hydrogenated.
However, hydrogenation of the monocyclic aromatic hydrocarbons negates the object of
25 the present invention. Accordingly, the loss of monocyclic aromatic hydrocarbons by
4
29
hydrogenation in the hydrogenation reaction step, reported relative to a value of 100% by
mass for the mass of monocyclic aromatic hydrocarbons prior to the hydrogenation
reaction step, is preferably not more than 5% by mass. The reaction conditions required
to achieve such minimal loss substantially satisfy the reaction condition ranges described
5 above for the first embodiment, but in order to avoid excessive hydrogenation of the
monocyclic aromatic hydrocarbons, the hydrogenation is preferably performed at a
higher temperature than that used in the first embodiment.
[0040]
For example, the hydrogenation reaction temperature varies depending on the
10 hydrogenation catalyst used, but is typically within a range from 250 to 45Q"C,
preferably from 300 to 400°C, and more preferably from 320 to 380*C.
[0041]
In the refining and collection step (p), the monocyclic aromatic hydrocarbons or
the benzene/toluene/xylene is collected, and the fraction that is heavier than the
15 monocyclic aromatic hydrocarbons is separated and removed, This fraction that is
heavier than the monocyclic aromatic hydrocarbons is a heavy fraction of 9 or more
carbon number, and contains mainly hydrogenation reaction products of poly cyclic
aromatic hydrocarbons and non-hydrogenated polycyciic aromatic hydrocarbons. ;
[0042] 20 In the heavy fraction discharge step (q), in a similar manner to that described for the heavy fraction discharge step (d) in the first embodiment, the amount of the heavy
fraction discharged outside the system is preferably not more than 90% by mass of the f
heavy fraction, more preferably not more than 50% by mass, and still more preferably
20% by mass or less. Although there are no particular limitations on the lower limit for [
25 the amount of the heavy fraction discharged outside the system, an amount of at least l
I
I
0.5% by mass is preferable. t
[0043] |
i
i
In the recycling step (r), the hydrogenation reaction product of the heavy |
fraction that was not discharged outside the system is mixed with the feedstock oil and :
5 returned to the cracking and reforming reaction step. •
In this embodiment, in a similar manner to that described for the first
embodiment, the hydrogenation reaction product of the heavy fraction is returned to the
cracking and reforming reaction step, and therefore the heavy fraction that represents a
by-product can be used as a feedstock for producing monocyclic aromatic hydrocarbons,
10 As a result, the amount of by-products can be reduced, and the production of monocyclic
aromatic hydrocarbons can be increased. Further, hydrogen transfer reactions within
the cracking and reforming reaction step can also bo accelerated, Accordingly, the
overall yield of monocyclic aromatic hydrocarbons relative to the amount of feedstock
oil supplied can be increased.
15 [0044]
[Third Embodiment]
Athird embodiment of the method for producing monocyclic aromatic j
hydrocarbons according to the present invention is described below. I
The method for producing monocyclic aromatic hydrocarbons according to tin's ;
20 embodiment is a method for producing monocyclic aromatic hydrocarbons from a
I
i
feedstock oil that represents an embodiment of aspect [5] of the present invention, and f
i
includes the steps (s) to (z) described below (see FIG 3). I
I
(s) A hydrogenation reaction step of hydrogenating the feedstock oil. (
i
|
(t) A cracking and reforming reaction step of bringing the hydrogenation reaction {
j
25 product obtained in the hydrogenation reaction step into contact with a monocyclic f
t
31 aromatic hydrocarbon production catalyst, and reacting the hydrogenation reaction
product to obtain a product containing monocyclic aromatic hydrocarbons, i
(u) A separation step of separating the product obtained in the cracking and
reforming reaction step into a plurality of fractions.
5 (v) Arefming and collection step of refining and collecting monocyclic aromatic
hydrocarbons separated in the separation step.
(w) A heavy fraction discharge step of discharging outside the system a portion of
the heavy fraction of 9 or more carbon number (hereinafter referred to as simply the
"heavy fraction") obtained from a fraction separated in the separation step.
10 (x) A recycling step of returning, to the hydrogenation reaction step, the heavy
fraction that was not discharged outside the system in the heavy fraction discharge step,
(y) A hydrogen recovery step of recovering, from the gas component separated in
the separation step, the hydrogen produced as a byproduct in the cracking and reforming
reaction step.
15 (z) A. hydrogen supply step of supplying the hydrogen recovered in the hydrogen
recovery step to the hydrogenation reaction step,
Of the steps (s) to (z) described above, the steps (s), (t), (v) and (x) are essential
steps in the method according to the third embodiment, whereas the steps (u), (w), (y)
and (z) are optional steps.
20 [0045]
The hydrogenation reaction step (s) of the present embodiment may use the
same hydrogenation catalyst as that used in the hydrogenation reaction step (f) of the first
embodiment.
In the hydrogenation reaction step (s), instead of the heavy fraction that was
25 treated in the hydrogenation reaction step (£) of the first embodiment, either the feedstock
M
i 32 ;
j oil for the cracking and reforming reaction step (a) of the first embodiment, or a mixed
Oil of the feedstock oil and the heavy fraction returned to the hydrogenation reaction step
in the recycling step (x), is hydrotreated. Besides this difference in the oil undergoing
treatment, the reaction conditions satisfy the ranges described for the first embodiment,
i
I 5 although the conditions may need to be adjusted appropriately within those ranges.
j In the hydrogenation reaction step (s), a hydrogenation reaction product is
| obtained from a mixture of the feedstock oil and the heavy fraction, but the amount of
\ poly cyclic aromatic hydrocarbons within the hydrogenation reaction product is
\ preferably not more than 20% by mass, and more preferably not more than 10% by mass,
j 10 Further, the amount of saturated hydrocarbons is preferably not mors than 60% by mass,
•I and more preferably not more than 40% by mass.
1
I Provided the ratio between the palycyclic aromatic hydrocarbons and saturated
j hydrocarbons within the hydrogenation reaction product satisfies the ranges described
above, the yield of monocyclic aromatic hydrocarbons in the subsequent cracking and
15 reforming reaction step (t) can be improved.
[0045]
The cracking and reforming reaction step (t) may be performed in the same
manner as the cracking and reforming reaction step (a) in the first embodiment,
! The separation step (u) may be performed in the same manner as the separation
20 step (b) in the first embodiment.
The refining and collection step (v) may be performed in the same manner as the
refining and collection step (c) in the first embodiment.
The heavy fraction discharge step (w) may be performed in the same manner as
the heavy fraction discharge step (d) in the first embodiment.
25 In the recycling step (x), the heavy traction that was not discharged outside the
33
system is mixed with the feedstock oil and returned to the hydrogenation reaction step.
The heavy fraction typically contains .from 50 to 95% by mass of polycyclic
aromatic hydrocarbons, and generates an extremely large amount of beat in the
hydrogenation reaction, meaning heat generation must be suppressed, but in the present
5 embodiment, by returning the heavy fraction to the hydrogenation reaction step and
mixing the heavy fraction with the feedstock oil, the polycyclic aromatic hydrocarbon
concentration, which was 50 to' 95% by mass within the heavy fraction, is preferably
reduced to not more than 50% by mass, more preferably not more than 30% by mass, and
still more preferably 20% by mass or less, thus enabling suppression of heat generation
10 in the hydrogenation reaction step.
Further, because the heavy fraction is supplied, via the hydrogenation reaction
step, to the cracking and reforming reaction step, the heavy fraction by-product can also
be used as a feedstock for obtaining monocyclic aromatic hydrocarbons. As a result,
not only can the amount of by-products be reduced, but the amount of monocyclic
15 aromatic hydrocarbons produced can be increased. Moreover, hydrogen transfer
reactions in the cracking and reforming reaction step can be accelerated, For these
reasons, the overall yield of monocyclic aromatic hydrocarbons relative to the amount of
feedstock oil supplied can be increased,
The amount of the heavy fraction mixed with the feedstock oil may be selected ;
20 appropriately so that the polycyclic aromatic hydrocarbon concentration within the mixed
oil satisfies the range described above (not more than 50% by mass). Typically, the
amount of the heavy fraction is equivalent to a mass ratio within a range from 15 to 70
relative to a value of 100 for the feedstock oil.
The hydrogen recover)' step (y) may be performed in the same manner as the
25 hydrogen recovery step (g)ofthe first embodiment.
4
34
The hydrogen supply step (2) may be performed in the same manner as the
hydrogen supply step (h) of the first embodiment.
[0047]
[Other Embodiments]
5 The present invention is not limited to the first, second and third embodiments
described above. For example, the hydrogen used in the hydrogenation reaction step
need not necessarily be the hydrogen produced as a by-product in the cracking and
reforming reaction step. Hydrogen obtained using a conventional hydrogen production
method may be used, or hydrogen obtained as a by-product in another contact cracking
10 method may be used.
Further, in the first and third embodiments, the heavy fraction discharge step
may be provided after the hydrogenation reaction step,
EXAMPLES
15 [0048]
(Reference Test 1: Test Examples 1 to 4)
1'he hydrogenation of polycyclic aromatic hydrocarbons was investigated
Specifically, 90 mL of each of the polycyclic aromatic hydrocarbon samples shown in
Table 1 was hydrogenated inside a 200 mL autoclave under the reaction conditions
20 shown in Table 1. The results of analyzing the reaction products are shown in Table 1.
35
[0049]
[Table 1]
t o g 1 8 J I g "» « S ?
5 111 * H is la g* I* i*
H * 3? | [ j& | W "-' ^ ^ s-
1 Naphthalene Ni catalyst "' 160 1.5 3 26 74 0
2 Naphthalene Ni catalyst *l 160 1.5 (5 62 38 0
Methyltetralin .,
„. . *t il S9
3 39% by mass Ni catalyst 160 1.5 3 , , , . . 0
, , •, , , (some methyl (some methyl
Methylnaphthalene ' • ^
groups) groups)
61% by mass _ i . . . I
4 Naphthalene NiMo catalyst '2 350 4.0 "1 ' T 66 29
___J , 1, 1 .1 „ L L ™~—J——
* I Ni Catalyst: 50% by mass Ni/diatomaceous earth, 0,25 g
*2 NiMo catalyst: 0.5 g
5
[0050]
This Reference Test 1 revealed that hydrogenation of polycystic aromatic
hydrocarbons resulted in a conversion to decalin (naphthene) and tetralin
(naphthenoberizene). Further the test also revealed that the conditions could be selected
10 to enable preferential production of naphthenobenzene over naphthene.
[0051]
(Reference Test 2: Test Examples 11 to 17)
The production of monocyclic aromatic hydrocarbons from naphthene,
raaphthenobenzene and naphthalene was investigated, Specifically, using a
35 gallium-supporting MTI (amount of supported gallium: 1.6% by mass) as the monocyclic
aromatic hydrocarbon production catalyst, and using either a fixed bed or fiuidized bed
reaction format, reaction was performed under a reaction pressure of 0.3 MPa for a
3 6 '
contact time of 7 seconds, at the reaction temperature shown in Table 2. The yield of
monocyclic aromatic hydrocarbons is shown in Table 2.
[0052]
[Table 2]
Test I " 1 Reaction ~* Reaction " Monocyclic aromatic |
Feedstock !
Example format temperature (f,C) ; hydrocareons (% by mass) |
lT"~ Tetralin " "Fixed bed Wi T ' 53 ~j
12 Tetralin TixeTbed -Jyf— | ~ —43 ——,
i i •
" 13 ~~ DecaiTa ~ Fixed bed "~450 "" W
14 Decalin ^iiied~bed 538 | 11.
_____ „ _______ Fixed bed 53S 1 3 "
~ ^thyldecalin U%^i__ J T ^ ™ 4 ~
Methyltetralin 89% by mass j
17 J M e A y l d e c a l l t i l P / o b y i n a s r ^ ^ ^ 53g I ' ~
Methyltetralin 89% by mass !
[0053]
This Reference Test 2 revealed that only a very small amount of monocyclic
aromatic hydrocarbons is obtained from naphthalene, but that monocyclic aromatic
hydrocarbons could be produced favorably from decalin (naphthene) and tetralin
10 (naphthenobenzene), which are hydrogenated products of naphthalene. These results
confirmed that by hydrogenating naphthalene to form naphthenobenzene, the
naphthenobenzene could then be easily converted to monocyclic aromatic hydrocarbons.
[0054] . j
(Test Example 3: Examples I to 3, Comparative examples 1 and 2, and Reference }
J 5 Example 1) An LCO shown in Table 3(10 volume % distillation temperature: 224.5°C, 90 j
volume % distillation temperature: 349.5°C) was reacted using an MFI-type zeolite on
f
J /
which 0.2% by mass of gallium and 0.7% by mass of phosphorus had been supported as
the reaction catalyst, using either a fixed bed or fluicixed bed reaction format, and under
conditions including a reaction temperature of 538°C, a reaction pressure of 0.3 MPaQ
and a contact time between the LCO and the zeolite component of the catalyst of 7
5 seconds, thus producing monocyclic aromatic hydrocarbons. In the case of the fixed
bed reaction format, the MFI-type zeolite on -which 0.2% by mass of gallium arid 0.7%
by mass of phosphorus had been supported was used as the catalyst, whereas in the case
of the fluidized bed reaction format, a material prepared by adding a binder to the
MFI-type zeolite on which 0.2% by mass of gallium and 0.7% by mass of phosphorus
10 had been supported was used as the catalyst. As a result, monocyclic aromatic
hydrocarbons (benzene, toluene, xylene) were obtained at a yield of 40% by mass.
Further, investigation of the amount of polycyclic aromatic hydrocarbons within the
heavy fraction obtained following collection of the monocyclic aromatic hydrocarbons
revealed a result o£6%% by mass.
15 Subsequently, the above heavy fraction was hydrotreated using a commercially
available nickel-molybdenum catalyst, under conditions including a hydrogenation
reaction temperature of 350°C, a hydrogenation reaction pressure of 5 MPa, and LHSV «
0.5 h'1. The thus obtained hydrogenation reaction product contained 52% by mass of
compounds having one aromatic ring and 7% by mass of compounds having two or more
20 aromatic rings (polycyclic aromatic hydrocarbons), which was a lower polycyclic
aromatic hydrocarbon content than the feedstock LCO.
Next, as examples of recycling the hydrotreated heavy fraction into the
feedstock oil, the amount of the hydrotreated heavy fraction recycled was varied to
obtain the feedstock oils shown in Table 4, Each of these feedstock oils was reacted
25 using an MFI-type zeolite on which 0,2% by mass of gallium and 0.7% by mass of
38
phosphorus had been supported as the reaction catalyst, using either a fixed bed or
fluidized bed reaction format, and under conditions including a reaction temperature of
53$°C, a reaction pressure of 0,3 MPaQ and a contact time between the feedstock oil and
the zeolite component of the catalyst of 7 seconds, thus producing monocyclic aromatic
5 hydrocarbons. In the case of the fixed bed reaction format, the MFI-type zeolite on
which 0.2% by mass of gallium and 0.7% by mass of phosphorus had been supported
was used as the catalyst, whereas in the case of the fluidized bed reaction format, a
material prepared by adding a. binder to the MFI-type zeolite on which 0.2% by mass of
gallium and 0.7% by mass of phosphorus had been supported was used as the catalyst.
10 The yields of monocyclic aromatic hydrocarbons are shown in Table 4.
[0055]
[Table 3]
Feedstock Properties "" ! Analysis method
Density (measurement temperature: 15°C) I g/onr5 I 0 906 JIS K 2249
Kinematic viscosity (measurement temperature; 20°C) S/s 3.640 JISK22&3
Initial boiling point °C 175.5
10 volume % distillation temperature *C "" 224.5
Distillation
'30 volume % distillation temperature °C 274.0 J1SK2254
properties
90-volume % distillation temperature °C 34!>,5
End point ~ T "f)6.Q
Saturated fraction volume % 35
'Olefin fraction, vdume % 8 ':
total aromaUc fraction ~ ~ ~ volume % 57
Composition _________________ __
Monocyclic aromatic fraction volume % 23 JPI-5S-49
analysis „
Bicyclic aromatic fraction volume % 25
Tricvclic or higher aromatic volume % 9
fraction I
! :
.. l , j ...J,,,., ,,. .I,, - — I . i
*
39
[0056]
[Table 4]
j I ~" TMonocyclic aromatic
Reaction
Test Example 3 Feedstock oil hydrocarbons
format
(% by mass)
I Heavy fraction, hydrogenation reaction product' '
! Example 1 Fixed bed 44
(100% by mass)
Comparative . I
Heavy fraction (100% by mass) Fixed bed 8 j
example 1
Mixture of heavy fraction hydrogenation reaction I
Example 2 Fixed bed 40
product (30% by mass) and LCO (70% by mass)
Mixture of heavy fraction hydrogenation reaction >
Example 3 FluwJizedbed 36
product (30% by mass) and LCO (70% by mass)
Comparative Mixture of heavy fraction (30% by mass) and"
Fixed bed 2/
example 2 LCO (70% by mass)
Reference
LCO (100% by mass) Fixed bed 40
Example 1
5 [0057]
(Example 4)
An LC02 shown in Table 5(10 volume % distillation temperature: 215*C, 90
volume % distillation temperature: 318CC) was reacted using a catalyst prepared by
adding a binder to an MH-type zeolite on which 0.2% by mass of gallium and 0,7% by
.10 mass of phosphorus had been supported, using a fluidized bed reaction format, and under
conditions including a reaction temperature of 538eC, a reaction pressure.of 0.3 MPaQ
and a contact time between the LC02 and the zeolite component of the catalyst of 12
seconds, thus producing monocyclic aromatic hydrocarbons. As a result, monocyclic
aromatic hydrocarbons (benzene, toluene, xylene) were obtained at a yield of 35% by
15 mass. Further, investigation of the amount of polycyclic aromatic hydrocarbons within
40
the heavy fraction obtained following collection of the monocyclic aromatic
hydrocarbons revealed a result of 81% by mass.
Subsequently, the above heavy fraction was hydrotreated using a commercially
available nickel-molybdenum catalyst, under conditions including a hydrogenation
5 reaction temperature of 350°C, a hydrogenation reaction pressure of 5 MPa, and LHSV ~
0,5 h"!. The thus obtained hydrogenation reaction product contained 78% by mass of
compounds having one aromatic ring and 8% by mass of compounds having two or more
aromatic rings (polycyclic aromatic hydrocarbons), which was a lower polycyclic
aromatic hydrocarbon content than the feedstock LC02,
10 Next, a recycled oil prepared by mixing the thus obtained hydrogenation
reaction product with the LC02 in a mass ratio of hydrogenation reaction product;
LC02 of 30:70 was used as a feedstock oil, and this feedstock oil was reacted using a
catalyst prepared by adding a binder to an MFI-type zeolite on which 0.2% by mass of
gallium and 0.7% by mass of phosphorus had been supported, using a fluidized bed
.15 reaction format, and under conditions including a reaction temperature of 53 8°C, a
reaction pressure of 0.3 MPaQ and a contact time between the feedstock oil and the
zeolite component of the catalyst of 12 seconds, thus producing monocyclic aromatic
hydrocarbons. The yield of monocyclic aromatic hydrocarbons is shown in Table 6. [0058]
20 (Examples) !
An LC02 shown in Table 5(10 volume % distillation temperature: 21 S^C, 90
volume % distillation temperature: 318°C) was reacted using a catalyst prepared by
adding a binder to an MFI-type zeolite on which 0.2% by mass of gallium and 0,7% by mass of phosphorus had been supported, using a fluidized bed reaction format, and under ;
25 conditions including a reaction temperature of 538°C, a reaction pressure of 0.3 MPaG; •
*
41
and a contact time between the LC02 and the zeolite component of the catalyst of 12
seconds, thus producing monocyclic aromatic hydrocarbons. As a result, monocyclic
aromatic hydrocarbons (benzene, toluene, xylene) were obtained at a yield of 35% by
mass. Further, investigation of the amount of polycyclic aromatic hydrocarbons within
5 the heavy fraction obtained following collection of the monocyclic aromatic
hydrocarbons revealed a result of 81% by mass,
Subsequently, a mixed oil of the above heavy fraction (50% by mass) and the
LC02 (50% by mass) was hydrotreated using a commercially available
nickel-molybdenum catalyst, under conditions including a hydrogenation reaction
10 temperature of 350eC, a hydrogenation reaction pressure of 5 MPa, and LHSV = 0.5 h"1.
The thus obtained hydrogenation reaction product, contained 63% by mass of compounds
having one aromatic ring and 8% by mass of compounds having two or more aromatic
rings (polycyclic aromatic hydrocarbons), which was a lower polycyclic aromatic
hydrocarbon content than the heavy fraction
15 Next, a recycled oil prepared by mixing the thus obtained hydrogenation
reaction product with the LC02 in a mass ratio of hydrogenation reaction product:
LCQ2 of 30:70 was used as a feedstock oil, and this feedstock oil was reacted using a
catalyst prepared by adding a binder to an MFI-type zeolite on which 0.2% by mass of
gallium and 0.7% by mass of phosphorus had been supported, using a fluidized bed
20 reaction format, and under conditions including a reaction temperature of 538°C, a
reaction pressure of 0.3 MPaQ and a contact time between the feedstock oil and the
zeolite component of the catalyst of 12 seconds, thus producing monocyclic aromatic
hydrocarbons. The yield of monocyclic aromatic hydrocarbons is shown in Table 6.
[0059]
25 (Example 6)
42 :
An LC02 shown in Table S (10 volume % distillation temperature: 215"C, 90
volume % distillation temperature: 318°C) was reacted using a catalyst prepared by
adding a binder to an MH-type zeolite on which 0 2% by mass of gallium and 0,7% by
mass of phosphorus had been supported, using a fluidized bed reaction format, and under
5 conditions including a reaction temperature of 538*0, a reaction pressure of 0.3 MPaG,
and a contact time between the LC02 and the zeolite component of the catalyst of 12
seconds, thus effecting a cracking and reforming reaction. Following separation of a
gas component containing ethane and propane gas and hydrogen gas and the like, the
liquid component was hydrotreated using a commercially available nickel-molybdenum
10 catalyst, under conditions including a hydrogenation reaction temperature of 350°C, a
hydrogenation reaction pressure of 6 MPa, and LHSY - 0.5 h"1. Separation of the
resulting hydrogenation reaction product by distillation into a fraction containing
monocyclic aromatic hydrocarbons (benzene, toluene, xylene) and a. heavier fraction,
yielded 48% by mass of the fraction containing monocyclic aromatic hydrocarbons and
.15 52% by mass of the hydrogenated heavy fraction. The collected hydrogenated heavy
fraction contained 77% by mass of compounds having one aromatic ring and 8% by mass
of compounds having two or more aromatic rings (polycyclic aromatic hydrocarbons).
Subsequently, a recycled oil prepared by mixing the thus obtained hydrogenated
heavy fraction with the LC02 in a mass ratio of hydrogenated heavy fraction : LC02
20 of 30:70 was used as a feedstock oil, and this feedstock oil was reacted using a catalyst
prepared by adding a binder to an MFI-type zeolite on which 0.2% by mass of gallium
and 0.7% by mass of phosphorus had been supported, using a fluidized bed reaction
format, and under conditions including a reaction temperature of 538"C, a reaction
pressure of 0.3 MPaQ and a contact time between the feedstock oil and the zeolite
25 component of the catalyst of 12 seconds, thus producing monocyclic aromatic 43
hydrocarbons. The yield of monocyclic aromatic hydrocarbons is shown in Table 6.
[0060]
(Example 7)
AnLC02 shown in Table 5 (10 volume % distillation temperature: 215°C, 90
5 volume % distillation temperature: 318°C) was hydrotrested using a commercially
available nickel-molybdenum catalyst, under conditions including a hydrogenation
reaction temperature of 3 5 0°C, a hydrogenation reaction pressure of 5 MPa, and LHSV =
0.5 li\ thus yielding a hydrogenated LC02, The thus obtained hydrogenated LC02
was reacted using a fmidized bed, using a catalyst prepared by adding a binder to an
10 MFI-type zeolite on which 0.2% by mass of gallium and 0.7% by mass of phosphorus
had been supported, and under conditions including a reaction temperature of 53 S°C, a
reaction pressure of 0.3 MPaQ and a contact time between the hydrogenated LC02 and
the zeolite component of the catalyst of 12 seconds, thus effecting a cracking and
reforming reaction, As a result, monocyclic aromatic hydrocarbons (benzene, toluene.
15 xylene) were obtained at a yield of 40% by mass. Further, investigation of the amount
of polycyclic aromatic hydrocarbons within the heavy fraction obtained following
collection of the monocyclic aromatic hydrocarbons revealed a result of 79% by mass.
Subsequently, the heavy fraction, was mixed with the LC02 in a mass ratio of
heavy fraction : LC02 of 30:70, and this mixed oil was recycled to a stage within the
20 production method prior to the hydrogenation reaction step. A hydrotreatment was
performed under the hydrotreatment conditions described above, and the resulting
hydrogenation reaction product was reacted using a catalyst prepared by adding a binder
to an MFI-type zeolite on which 0,2% by mass of gallium and 0.7% by mass of
phosphorus had been supported, using a fiuidized bed reaction format, and under
25 conditions including a reaction temperature of 53S°C, a reaction pressure of 0.3 MPaG,
44
and a contact time with the zeolite component of the catalyst of 12 seconds, thus
producing monocyclic aromatic hydrocarbons. The yield of monocyclic aromatic
hydrocarbons is shown in Table 6.
f0061]
5 [Table 5]
1 Feedstock Properties Analysis method
t : J
i Density @15°C g/cnr" ~T~0.92Sf~~ JISK2249
Kinetnatic7iscosity'@l0sC InrF/s 2.8]? JISK22S3 ~
Initial boiling point ^CT^ 173
10 volume % distillation temperature °C 215 )
Distillation
50 volume % distillation temperature °C ~"" 265 JISK2234 ;
properties ^
90 volume % distillation temperature 'C 31S
End point °C 346"
Saturated fraction volume % 22,9 Olefin fraction volume % 2,!
Total aromatic fraction volume % 75
Composition
Monocyclic aromatic fraction volume % 27,6 JPI-5S-49
analysis _____„
Bicyclic aromatic fraction volume % 39,5
Tricyclic or higher aromatic volume % 7,9
fraction :
I I J 1 _„__ , I
45
[0062]
[Table 6]
Reaction J Monocyclic aromatic hydrocarbons
format ('% by mass)
Example 4 Fluidized bed 38
Example 5 Fluidized bed 36
Example 6 Fluidized bed ~37 "~™"~
~~"~Example 7 Fluidised bed " ?!
[0063]
5 The results of Examples 1 to 6 confirmed that by hydrogenating the heavy
fraction produced in the cracking and reforming reaction step, and then using the thus
obtained hydrogenation reaction product as a feedstock for the cracking and reforming
reaction step, monocyclic aromatic hydrocarbons could be produced, Moreover, the
result of Example 7 confirmed that monocyclic aromatic hydrocarbons could also be
10 produced by mixing a feedstock oil with the heavy fraction obtained upon treating the
feedstock oil in a hydrogenation reaction step and a cracking and reforming reaction step, ;
and then using the resulting mixed oil as a feedstock for performing a hydrogenation reaction step, followed by a cracking and reforming reaction step on the resulting
hydrogenation reaction product. In contrast, in Comparative Examples 3 and 2, when
15 the heavy fraction was not subjected to hydrogenation, but was rather used with no
further modification as the feedstock for producing monocyclic aromatic hydrocarbons,
only a very small amount of monocyclic aromatic hydrocarbons was obtained.
Basedonthese results, it is assumed that by-mixing-ahydrogenated-product-of
the heavy fraction with the feedstock oil, and then returning the mixed oil to the cracking
20 and reforming reaction step, the rate of production of by-products other than the
4
46
monocyclic aromatic hydrocarbons can be reduced, and the amount of monocyclic
aromatic hydrocarbons produced can be increased. Accordingly, by returning a
hydrogenation reaction product of the heavy fraction to the cracking and reforming
reaction step, the yield of monocyclic aromatic hydrocarbons can be improved.
5
INDUSTRIAL APPLICABILITY
[0064] I
The method for producing monocyclic aromatic hydrocarbons according to the
present invention enables the yield of monocyclic aromatic hydrocarbons obtained from ]
10 a feedstock oil having a 10 volume % distillation temperature of at least W C and a 90 I
volume % distillation temperature of not more than 3 80°C to be improved

CLAIMS
i. A method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number from a feedstock oil having a 10 volume % distillation temperature of at least
5 140*0 and a 90 volume % distillation temperature of not more than 3S0*C, the method
coniprising:
a cracking and reforming reaction step of bringing the feedstock oil into contact
witji a itionocyclic aromatic hydrocarbon production catalyst comprising a crystalline
aluminosilicate, and reacting the feedstock oil to obtain a product comprising monocyclic
10 aromatichydrocarbonsof 6 to 8 carbon number,
a refining and collection step of refining and collecting monocyclic aromatic
hydrocarbons of 6 to 8 carbon number that have been separated from the product
obtained in the crackling and reforming reaction step,
a hydrogenation reaction step of hydrogenating a heavy fraction of 9 or morels
carbon number separated from, the product obtained in the cracking and rcformimg
reaction step, arid
a recycling step of returning a heaw fi-action hydrogenation reaction product
obtained in the hydrogenation reaction step to the cracking and reforming reaction step.
20 2. The method for producing monocyclic aromatic hydrocarbons of 6 to 8 cai'bon
number according to claim 1, ftirther comprising a feedstock oil mixing step of mixing a
portion of the feedstock oil with the heavy fraction of 9 or more carbon number separated
from the product obtained in the cracking and reforming rsaction step.
25 3. A method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
48
number from a feedstock oil having a 10 volume % distillation temperature of at least
i40''C and a 90 volume % distillation temperature of not more than 380°C, the method
comprising:
a cracking and reforming reaction step of bringing the feedstock oil into contact
5 with a monocyclic aromatic hydrocarbon production catalyst comprising a cryBtailir.e
aluminosilicate, and reacting the feedstock oil to obtain a product comprising monocyclic
aromatic hydrocarbons of 6 to S carbon number,
a hydrogenation reaction step of hydrogenating a portion of the product obtained
in the cracking and reforming reaction step,
10 a refining and collection step of refining and collecting m,onocyc]ic aromatic
hydrocarbons of 6 to 8 carbon number by distilling a hydrogenation reaction product
obtained in the hydrogenation reaction step, and
a recycling step of returning a heavy fraction of 9 or more carbon number, which
has been separated and removed from the monocyclic aromatic hydrocarbons of 6 to 8
15 carbon number in the refining and collection step, to the cracking and reforming reaction
step.
4. The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number according to claim 3, fijrther comprising a feedstock oil mixing step of mixing a
20 portion of the feedstock oil with a portion of the product obtained in the cracking and
reforming reaction step.
5, A method for producing monocyclic aromatic hydrocai'bons of 6 to 8 carbon
number from a feedstock oil having a 10 volume % distillation temperature of at least
25 MO'C and a 90 volume % distillation temperature of not more than 380°C, the method
49
comprising;
a hydrogenation reaction step of hydrogenating ths feedstock oil,
a cracking and reforming reaction step of bringing a hydrogenated product
obtained in the hydrogenation reaction step into contact with a monocyclic aromatic
5 hydrocarbon production catalyst comprising a crystalline aiuminosilicate, and reacting
the hydrogenated product to obtain a product comprising monocyclic aromatic
hydrocarbons of 6 to 8 carbon number,
a refining and collection step of refining and collecting monocyclic aromatic
hydrocarbons of 6 to 8 carbon number that have been separated from the product
10 obtained in the cracking and reforming reaction step, and
a recycling step of returning a heavy fraction of 9 or mere carbon number
separated from the product obtained in the cracking and reforming reaction step to the
hydrogenation reaction step.
15 6, The method for producing monocyclic aromatic hydrocarbons of 6 to 8 cari^on
number according to claim 1, wherein the crystalline aluminosilicate contained within the
monocyclic aromatic hydrocarbon production catalyst used in the cracking and reforming
reaction step comprises a medium pore size zeolite and/or a large pore size zeolite as a
main component.
20
7, The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number according to claim 1, further comprising a hydrogen recovery step of recovering,
from the product obtained in the cracking and reforming reaction step, hydrogen that is
produced as a byproduct in the cracking and reforming reaction step, and a hydrogen
25 supply step of supplying the hydrogen recovered in the hydrogen, recovery step to the
liydrogetmtion re-aciion step.
8, The method for producing monccyciic aromatic hydrocarbons of 6 to S carbon
number according to claim 3, wherein the crystallliie alun^inosilicate contained within the
5 mcnocyclic aromatic hydrocarbon production catalyst used in the cracking and reforming
reaction step comprises a medium pore me zeolite and/or a large pcra size zeolite an i;t
main component.
9. The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
)v iiumber according to claim 3, flirther comprising a hydrogen recover^' step of recovering,
from the product obtained in the cracking and reforming reaction step, hydrogen that k
produced as a byproduct in the cracking and refonning reaction step, and a hydrogen
?i(4-)ply step of supplying the hydrogen recovered in the hydrogen recovery step to the
hydrogenation reaction step.
15
10: The method for produciwg mouocyclio ai-omatic bydrocsjbons of 6 to 8 carbon
lUimbet" according to claim 5, •wlierein the ciystalline aiuininosilicate contained within themonocyclic
aromatic hydrocarbon production catalyst used in the cracking and reforming
reaction step comprises a medium pore size zeolite and/or a large pore si?.e zeolite as a
20 main component,
11 - The method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon
number according to claim 5, flirther comprising a hydrogen recovery step of .tecoyerini?,
from tlie product obtained in the cracking aiid reforming reaction step, hydrogen that is
25 produced as a byproduct in the cracking and reforming reaction step, and a fiydiogt'n
supply step of supplying the hydrogen recovered in the hydrogen recovery step to the
hydrogenation reaction step,