U.S. patent application number 13/822556 was filed with the patent office on 2013-07-18 for method for producing aromatic hydrocarbons.
This patent application is currently assigned to JX NIPPON OIL & ENERGY CORPORATION. The applicant listed for this patent is Ryoji Ida, Yasuyuki Iwasa, Masahide Kobayashi, Shinichiro Yanagawa. Invention is credited to Ryoji Ida, Yasuyuki Iwasa, Masahide Kobayashi, Shinichiro Yanagawa.
Application Number | 20130184506 13/822556 |
Document ID | / |
Family ID | 45831639 |
Filed Date | 2013-07-18 |
United States Patent
Application |
20130184506 |
Kind Code |
A1 |
Yanagawa; Shinichiro ; et
al. |
July 18, 2013 |
METHOD FOR PRODUCING AROMATIC HYDROCARBONS
Abstract
Disclosed is a method for producing aromatic hydrocarbons
including a cracking reforming reaction step of bringing a
feedstock having a 10 vol % distillation temperature of 140.degree.
C. or higher and a 90 vol % distillation temperature of 380.degree.
C. or lower, into contact with a catalyst for monocyclic aromatic
hydrocarbon production containing a crystalline aluminosilicate to
cause the feedstock to react with the catalyst, and thereby
obtaining a product including monocyclic aromatic hydrocarbons
having 6 to 8 carbon numbers and a heavy oil fraction having 9 or
more carbon numbers; a step of separating the monocyclic aromatic
hydrocarbons and the heavy oil fraction from the product obtained
from the cracking reforming reaction step; a step of purifying the
monocyclic aromatic hydrocarbons separated in the separating step,
and collecting the hydrocarbons; and a step of separating
naphthalene compounds from the heavy oil fraction separated in the
separating step, and collecting the naphthalene compounds.
Inventors: |
Yanagawa; Shinichiro;
(Chiyoda-ku, JP) ; Ida; Ryoji; (Chiyoda-ku,
JP) ; Kobayashi; Masahide; (Chiyoda-ku, JP) ;
Iwasa; Yasuyuki; (Chiyoda-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yanagawa; Shinichiro
Ida; Ryoji
Kobayashi; Masahide
Iwasa; Yasuyuki |
Chiyoda-ku
Chiyoda-ku
Chiyoda-ku
Chiyoda-ku |
|
JP
JP
JP
JP |
|
|
Assignee: |
JX NIPPON OIL & ENERGY
CORPORATION
Chiyoda-ku, Tokyo
JP
|
Family ID: |
45831639 |
Appl. No.: |
13/822556 |
Filed: |
September 14, 2011 |
PCT Filed: |
September 14, 2011 |
PCT NO: |
PCT/JP2011/070925 |
371 Date: |
March 12, 2013 |
Current U.S.
Class: |
585/256 ;
585/476 |
Current CPC
Class: |
C10G 35/095 20130101;
C10G 69/08 20130101; C10G 45/44 20130101; C10G 2300/203 20130101;
C10G 63/02 20130101; C10G 11/05 20130101; C10G 69/00 20130101; C10G
2300/301 20130101; C10G 2400/30 20130101 |
Class at
Publication: |
585/256 ;
585/476 |
International
Class: |
C10G 11/05 20060101
C10G011/05 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 2010 |
JP |
2010-205903 |
Claims
1. A method for producing aromatic hydrocarbons, the method
comprising the steps of: bringing a feedstock having a 10 vol %
distillation temperature of 140.degree. C. or higher and a 90 vol %
distillation temperature of 380.degree. C. or lower, into contact
with a catalyst for monocyclic aromatic hydrocarbon production
containing a crystalline aluminosilicate to cause the feedstock to
react with the catalyst, and thereby obtaining a product including
monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers and a
heavy oil fraction having 9 or more carbon numbers; separating
respectively the monocyclic aromatic hydrocarbons having 6 to 8
carbon numbers and the heavy oil fraction having 9 or more carbon
numbers from the product obtained from the cracking reforming
reaction step; purifying the monocyclic aromatic hydrocarbons
having 6 to 8 carbon numbers thus separated in the separation step,
and collecting the monocyclic aromatic hydrocarbons having 6 to 8
carbon numbers; and separating naphthalene compounds that include
at least naphthalene, from the heavy oil fraction having 9 or more
carbon numbers thus separated in the separation step, and
collecting the naphthalene compounds.
2. The method for producing aromatic hydrocarbons according to
claim 1, wherein the step of collecting naphthalene is a process of
separating and collecting methylnaphthalene and/or
dimethylnaphthalene, and naphthalene.
3. The method for producing aromatic hydrocarbons according to
claim 1, further comprising the steps of: hydrogenating a remaining
fraction obtained by separating naphthalene compounds in the step
of collecting naphthalene, and obtaining a hydrogenation reaction
product; and recycling the hydrogenation reaction product to the
step of cracking reforming reaction.
4. The method for producing aromatic hydrocarbons according to
claim 1, wherein in the step of collecting naphthalene, the
apparatus for separating and collecting naphthalene compounds
including naphthalene is a distillation apparatus.
5. The method for producing aromatic hydrocarbons according to
claim 1, wherein the crystalline aluminosilicate comprises a
zeolite with medium-sized pores and/or a zeolite with large-sized
pores as main components.
6. The method for producing aromatic hydrocarbons according to
claim 1, wherein the reaction temperature employed when the
feedstock is allowed to react with the catalyst for monocyclic
aromatic hydrocarbon production in the step of cracking reforming
reaction is from 400.degree. C. to 650.degree. C.
7. The method for producing aromatic hydrocarbons according to
claim 1, wherein the reaction pressure employed when the feedstock
is allowed to react with the catalyst for monocyclic aromatic
hydrocarbon production in the step of cracking reforming reaction
is from 0.1 MPaG to 1.5 MPaG.
8. The method for producing aromatic hydrocarbons according to
claim 1, wherein the contact time for bringing the feedstock into
contact with the catalyst for monocyclic aromatic hydrocarbon
production in the step of cracking reforming reaction is from 1
second to 300 seconds.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing
aromatic hydrocarbons.
[0002] Priority is claimed on Japanese Patent Application No.
2010-205903, filed Sep. 14, 2010, the content of which is
incorporated herein by reference.
BACKGROUND ART
[0003] Light cycle oil (hereinafter, referred to as "LCO"), which
is a cracked light oil produced by a fluid catalytic cracking
(hereinafter, referred to as "FCC") units, contains a large amount
of polycyclic aromatic hydrocarbons and has been utilized as light
oil or heavy oil. However, in recent years, investigations have
been conducted to obtain, from LCO, monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers (for example, benzene,
toluene, xylene, ethylbenzene and the like), which can be utilized
as high octane value gasoline base materials or petrochemical
feedstocks and have a high added value.
[0004] For example, Patent Documents 1 to 3 suggest methods for
producing monocyclic aromatic hydrocarbons from polycyclic aromatic
hydrocarbons that are contained in LCO and the like in a large
amount, by using a zeolite catalyst.
PRIOR ART DOCUMENTS
Patent Document
[0005] [Patent Document 1] Japanese Unexamined Patent Application,
First Publication No. H03-2128 [0006] [Patent Document 2] Japanese
Unexamined Patent Application, First Publication No. H03-52993
[0007] [Patent Document 3] Japanese Unexamined Patent Application,
First Publication No. H03-26791
DISCLOSURE OF INVENTION
Technical Problem
[0008] However, in regard to the methods described in Patent
Documents 1 to 3, it cannot be said that the yield of monocyclic
aromatic hydrocarbons having 6 to 8 carbon numbers is sufficiently
high.
[0009] Furthermore, in recent years, new effective utilization of
LCO is anticipated. Specifically, in addition to efficient
production of monocyclic aromatic hydrocarbons having 6 to 8 carbon
numbers, such as benzene, toluene, xylene and ethylbenzene, it is
expected to produce other chemical products as effective
by-products, by the same process or only by adding a new process to
part of the process.
[0010] The invention was achieved in view of the circumstances
described above, and it is an object of the invention to provide a
method for producing aromatic hydrocarbons, by which monocyclic
aromatic hydrocarbons having 6 to 8 carbon numbers can be produced
in high yields from a feedstock containing polycyclic aromatic
hydrocarbons, and also, other chemical products, for example,
aromatic hydrocarbons other than the monocyclic aromatic
hydrocarbons, can be produced.
Solution to Problem
[0011] The present inventors conducted thorough investigations in
order to achieve the object described above, and as a result, they
obtained the following findings.
[0012] Since LCO contains a large amount of polycyclic aromatic
hydrocarbons, if this is subjected to a cracking reforming reaction
treatment, a relatively large amount of a heavy oil fraction having
9 or more carbon numbers can also be obtained in addition to the
monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers. In
regard to this heavy oil fraction, an investigation has been
conducted to merely find that the heavy oil fraction may be
collected as a light oil/kerosene base material, or may be recycled
as a feedstock of the monocyclic aromatic hydrocarbons.
[0013] Thus, the present inventors analyzed in detail the
components of the heavy oil fraction in order to promote effective
utilization of the heavy oil fraction, and as a result, the
inventors found that the heavy oil fraction contains a large
proportion of naphthalene or alkylnaphthalenes. Further, based on
such findings, the inventors further conducted investigations
regarding the production of naphthalene as a chemical product, in
parallel to the production of the monocyclic aromatic hydrocarbons,
and as a result, the inventors achieved the invention.
[0014] That is, the method for producing aromatic hydrocarbons of
the invention includes:
[0015] a cracking reforming reaction step of bringing a feedstock
having a 10 vol % distillation temperature of 140.degree. C. or
higher and a 90 vol % distillation temperature of 380.degree. C. or
lower, into contact with a catalyst for monocyclic aromatic
hydrocarbon production containing a crystalline aluminosilicate to
cause the feedstock to react with the catalyst, and thereby
obtaining a product including monocyclic aromatic hydrocarbons
having 6 to 8 carbon numbers and a heavy oil fraction having 9 or
more carbon numbers;
[0016] a separation step of respectively separating the monocyclic
aromatic hydrocarbons having 6 to 8 carbon numbers and the heavy
oil fraction having 9 or more carbon numbers from the product
obtained from the cracking reforming reaction step;
[0017] a purification and collecting step of purifying the
monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers thus
separated in the separation step, and collecting the monocyclic
aromatic hydrocarbons having 6 to 8 carbon numbers; and
[0018] a naphthalene collecting step of separating naphthalene
compounds that include at least naphthalene, from the heavy oil
fraction having 9 or more carbon numbers thus separated in the
separation step, and collecting the naphthalene compounds.
[0019] Furthermore, in regard to the method for producing aromatic
hydrocarbons, the naphthalene collection step is preferably a step
of separating and collecting methylnaphthalene and/or
dimethylnaphthalene, and naphthalene.
[0020] Furthermore, the method for producing aromatic hydrocarbons
preferably includes:
[0021] a hydrogenation reaction step of hydrogenating the fraction
remaining after naphthalene compounds have been separated in the
naphthalene collecting step and obtaining a hydrogenation reaction
product; and
[0022] a recycling step of recycling the hydrogenation reaction
product to the cracking reforming reaction step.
[0023] Also, in regard to the method for producing aromatic
hydrocarbons, the apparatus for separating and collecting
naphthalene compounds including naphthalene in the naphthalene
collecting step is preferably a distillation apparatus.
[0024] Furthermore, in regard to the method for producing aromatic
hydrocarbons, it is preferable that the crystalline aluminosilicate
contain, as main components, a zeolite with medium-sized pores
and/or a zeolite with large-sized pores.
[0025] Furthermore, in regard to the method for producing aromatic
hydrocarbons, it is preferable to set the reaction temperature
employed when the feedstock and the catalyst for monocyclic
aromatic hydrocarbon production in the cracking reforming reaction
step, to a temperature ranging from 400.degree. C. to 650.degree.
C.
[0026] Also, in regard to the method for producing aromatic
hydrocarbons, it is preferable to set the reaction pressure
employed when the feedstock and the catalyst for monocyclic
aromatic hydrocarbon production in the cracking reforming reaction
step, to a pressure ranging from 0.1 MPaG to 1.5 MPaG.
[0027] Furthermore, in regard to the method for producing aromatic
hydrocarbons, it is preferable to set the contact time for bringing
the feedstock into contact with the catalyst for monocyclic
aromatic hydrocarbon production in the cracking reforming reaction
step, to a period ranging from 1 to 300 seconds.
Advantageous Effects of Invention
[0028] According to the method for producing aromatic hydrocarbons
of the invention, monocyclic aromatic hydrocarbons having 6 to 8
carbon numbers can be produced with a relatively high yield from a
feedstock including polycyclic aromatic hydrocarbons, and in
addition, naphthalene compounds including naphthalene can be
produced as other chemical products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a diagram for explaining an embodiment of the
method for producing aromatic hydrocarbons of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] Hereinafter, the method for producing aromatic hydrocarbons
of the invention will be described in detail.
[0031] FIG. 1 is a diagram for explaining an embodiment of the
method for producing aromatic hydrocarbons of the invention, and
the method for producing aromatic hydrocarbons of the present
embodiment is a method for producing monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers from a feedstock, and
also producing naphthalene compounds including naphthalene.
[0032] That is, the method for producing aromatic hydrocarbons of
the present embodiment preferably includes, as shown in FIG. 1:
[0033] (a) a cracking reforming reaction step of bringing a
feedstock into contact with a catalyst for monocyclic aromatic
hydrocarbon production to cause the feedstock to react with the
catalyst, and obtaining a product including monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers and a heavy oil fraction
having 9 or more carbon numbers;
[0034] (b) a separation step of separating the product produced in
the cracking reforming reaction step into plural fractions;
[0035] (c) a hydrogen collecting step of collecting hydrogen that
is produced as a by-product in the cracking reforming reaction step
from the gas components separated in the separation step;
[0036] (d) an LPG collecting step of collecting LPG that is
produced as a by-product in the cracking reforming reaction step
from a liquid fraction separated in the separation step;
[0037] (e) a purification and collection step of purifying and
collecting monocyclic aromatic hydrocarbons from a liquid fraction
separated in the separation step;
[0038] (f) a naphthalene collecting step of separating and
collecting naphthalene compounds including at least naphthalene,
from a heavy oil fraction having 9 or more carbon numbers that is
obtainable from the liquid fraction separated in the separation
step;
[0039] (g) a hydrogen supply step of supplying the hydrogen
collected in the hydrogen collecting step to a hydrogenation
reaction step;
[0040] (h) a hydrogenation reaction step of hydrogenating the
fraction remaining after naphthalene compounds have been separated
in the naphthalene collecting step; and
[0041] (i) a recycling step of recycling the hydrogenation reaction
product obtained in the hydrogenation reaction step to the cracking
reforming reaction step.
[0042] It should be noted, among the steps of (a) to (i), the steps
of (a), (b), (e) and (f) are essential steps for the invention
related to claim 1 of the invention, and the other steps are
optional steps.
[0043] Hereinafter, the various steps will be specifically
described.
<Cracking Reforming Reaction Step>
[0044] In the cracking reforming reaction step, a feedstock is
brought into contact with a catalyst for monocyclic aromatic
hydrocarbon production, polycyclic aromatic hydrocarbons are
partially hydrogenated by a hydrogen transfer reaction from
saturated hydrocarbons by using the saturated hydrocarbons included
in the feedstock as a hydrogen donating source, and the polycyclic
aromatic hydrocarbons are converted to monocyclic aromatic
hydrocarbons by ring-opening. Furthermore, conversion to monocyclic
aromatic hydrocarbons can also be achieved by cyclizing and
dehydrogenating saturated hydrocarbons obtainable from the
feedstock or in a cracking step. Also, monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers can also be obtained by
cracking monocyclic aromatic hydrocarbons having 9 or more carbon
numbers. Thereby, a product including monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers and a heavy oil fraction
having 9 or more carbon numbers is obtained. This product includes,
in addition to the monocyclic aromatic hydrocarbons and the heavy
oil fraction, hydrogen, methane, ethane, ethylene, LPG (propane,
propylene, butane, butene and the like), and the like. Furthermore,
the heavy oil fraction includes large amounts of naphthalene,
methylnaphthalene, and dimethylnaphthalene. Meanwhile, in the
present specification, these naphthalene, methylnaphthalene and
dimethylnaphthalene are collectively described as "naphthalene
compounds".
[0045] In the cracking reforming reaction step, components such as
naphthenobenzenes, paraffins and naphthenes in the feedstock can be
eliminated by producing monocyclic aromatic hydrocarbons, and
polycyclic aromatic hydrocarbons can be converted mainly to
naphthalene compounds with a high added value, such as naphthalene,
methylnaphthalene and dimethylnaphthalene, which have fewer side
chains, by cleaving alkyl side chains simultaneously with the
conversion of polycyclic aromatic hydrocarbons to monocyclic
aromatic hydrocarbons. That is, in the present cracking reforming
reaction step, monocyclic aromatic hydrocarbons can be produced
with high yield, and at the same time, other components having a
boiling point close to that of naphthalene compounds can be reduced
as much as possible. Therefore, when the amount of production of
naphthalene compounds having short side chains is increased, and
the content ratio of naphthalene compounds in the oil produced by
the cracking reforming reaction is increased, collection of
naphthalene compounds that will be described below can be
efficiently carried out.
[0046] Light cycle oil or the like that is used as a main feedstock
originally contains a large proportion of naphthalene compounds,
but at the same time, contains large proportions of other
components such as naphthenobenzenes and paraffins. Therefore, the
content ratio of naphthalene compounds relative to the total amount
of the feedstock is small, and it is very difficult to directly
separate and purify naphthalene compounds from the feedstock. In
the case of performing separation and purification of naphthalene
compounds from the feedstock, high energy consumption type
processes such as crystallization should be employed, which is not
preferable.
[0047] The present cracking reforming reaction step enables the
proportion of useful aromatic hydrocarbons that can be collected,
to be increased to a large extent as described above.
[0048] (Feedstock)
[0049] The feedstock that is used in the present embodiment is an
oil having a 10 vol % distillation temperature of 140.degree. C. or
higher and a 90 vol % distillation temperature of 380.degree. C. or
lower. Since oil having a 10 vol % distillation temperature of
lower than 140.degree. C. is light, monocyclic aromatic
hydrocarbons are produced by very light fraction, and the oil is
not suitable for the present embodiment. Furthermore, when an oil
having a 90 vol % distillation temperature of higher than
380.degree. C. is used, not only the yield of monocyclic aromatic
hydrocarbons is lowered, but also the amount of coke deposition on
the catalyst for monocyclic aromatic hydrocarbon production
increases, and the catalytic activity tends to undergo a rapid
decrease.
[0050] The 10 vol % distillation temperature of the feedstock is
preferably 150.degree. C. or higher, and the 90 vol % distillation
temperature of the feedstock is preferably 360.degree. C. or lower.
On the other hand, the upper limit of the 10 vol % distillation
temperature and the lower limit of the 90 vol % distillation
temperature of the feedstock are not particularly limited, but from
the viewpoint that monocyclic aromatic hydrocarbons having 6 to 8
carbon numbers and naphthalene compounds can be efficiently
produced, the 10 vol % distillation temperature is preferably
210.degree. C. or lower, and the 90 vol % distillation temperature
is preferably 240.degree. C. or higher.
[0051] Meanwhile, the 10 vol % distillation temperature and 90 vol
% distillation temperature as used herein mean values measured
according to JES K2254 "Petroleum products--Distillation test
methods".
[0052] Examples of the feedstock having a 10 vol % distillation
temperature of 140.degree. C. or higher and a 90 vol % distillation
temperature of 380.degree. C. or lower include LCO produced by a
FCC units, a hydrogenated purified oil of LCO, other cracked light
oils such as hydrogenated cracked light oil and thermally cracked
light oil, coal liquefied oil, heavy oil hydrogenated cracked
purified oil, straight run kerosene, straight run light oil, coker
kerosene, coker light oil, and purified oil obtained by
hydrogenation cracking oil sand.
[0053] Furthermore, if the feedstock contains a large amount of
polycyclic aromatic hydrocarbons, the yield of monocyclic aromatic
hydrocarbons decreases. Therefore, the content of polycyclic
aromatic hydrocarbons (polycyclic aromatic content) in the
feedstock is preferably 50 vol % or less, and more preferably 40
vol % or less. However, as will be described below, when it is
intended to further increase the yield of naphthalene (or
naphthalene compounds) produced together with the monocyclic
aromatic hydrocarbons, the polycyclic aromatic content in the
feedstock may be adjusted to, for example, 50 vol % or more.
However, even in that case, the content of aromatic hydrocarbons
having 3 or more rings is preferably set to 30 vol % or less, and
more preferably set to 15 vol % or less.
[0054] The term polycyclic aromatic content as used herein means
the total value of the content of bicyclic aromatic hydrocarbons
(bicyclic aromatic content) and the content of aromatic
hydrocarbons with 3 or more rings (tricyclic or higher-cyclic
aromatic content), which are measured according to JPI-5S-49
"Petroleum products--Hydrocarbon type test methods--high
performance liquid chromatographic method", or analyzed by an FID
gas chromatographic method. Hereinbelow, when the contents of
polycyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons,
and tricyclic or higher-cyclic aromatic hydrocarbons are expressed
in vol %, the content was measured by the method of JPI-5S-49,
while when the content is expressed in mass %, the content was
measured by an FID gas chromatographic method.
[0055] (Reaction Mode)
[0056] Examples of the reaction mode employed when the feedstock is
brought into contact with a catalyst for monocyclic aromatic
hydrocarbons to react therewith, include a fixed bed, a mobile bed,
and a fluidized bed. According to the present embodiment, since
heavy oil components are used as a feedstock, a fluidized bed which
is capable of continuously removing the coke component adhering to
the catalyst and is capable of stably carrying out the reaction is
preferred. Particularly, a continuously regenerative type fluidized
bed in which a catalyst is circulated between a reactor and a
regenerator so that reaction-regeneration can be continuously
repeated, is particularly preferred. When brought into contact with
the catalyst for monocyclic aromatic hydrocarbon production, the
feedstock is preferably in a gas phase. Furthermore, the feedstock
may also be diluted with a gas as necessary.
[0057] (Catalyst for Monocyclic Aromatic Hydrocarbon
Production)
[0058] The catalyst for monocyclic aromatic hydrocarbon production
contains a crystalline aluminosilicate.
[0059] [Crystalline Aluminosilicate]
[0060] From the viewpoint of further increasing the yield of
monocyclic aromatic hydrocarbons, the crystalline aluminosilicate
is preferably a zeolite with medium-sized pores and/or a zeolite
with large-sized pores.
[0061] The zeolite with medium-sized pores is a zeolite having a
10-membered ring skeletal structure, and examples of the zeolite
with medium-sized pores include zeolites having AEL type, EUO type,
FER type, HEU type, MEL type, MFI type, NES type, TON type, and WEI
type crystal structures. Among these, MFI type zeolite is preferred
from the viewpoint that the yield of monocyclic aromatic
hydrocarbons can be further increased.
[0062] The zeolite with large-sized pores is a zeolite having a
12-membered ring skeletal structure, and examples of the zeolite
with large-sized pores include zeolites having AFI type, ATO type,
BEA type, CON type, FAU type, GME type, LTL type, MOR type, MTW
type, and OFF type crystal structures. Among these, from the
viewpoint that the total yield of monocyclic aromatic hydrocarbons
and aliphatic hydrocarbons having 3 to 4 carbon numbers can be
further increased, BEA type zeolite is preferred.
[0063] However, as will be described below, when it is intended to
further increase the yield of naphthalene (or naphthalene
compounds) that are produced together with monocyclic aromatic
hydrocarbons, a catalyst containing a crystalline aluminosilicate
other than the MFI type or BEA type zeolite described above may
also be used.
[0064] Furthermore, the crystalline aluminosilicate may also
contain a zeolite with small-sized pores, having a 10-membered or
fewer-membered ring skeletal structure, and a zeolite with
ultra-large-sized pores, having a 14-membered or more-membered ring
skeletal structure, in addition to the zeolite with medium-sized
pores and the zeolite with large-sized pores.
[0065] Here, examples of the zeolite with small-sized pores include
zeolites having ANA type, CHA type, ERI type, GIS type, KFI type,
LTA type, NAT type, PAU type and YUG type crystal structures.
[0066] Examples of the zeolite with ultra-large-sized pores include
zeolites having CLO type and VPI type crystal structures.
[0067] When the cracking reforming reaction step is carried out as
a fixed bed reaction, the content of the crystalline
aluminosilicate in the catalyst for monocyclic aromatic hydrocarbon
production is preferably 60 mass % to 100 mass %, more preferably
70 mass % to 100 mass %, and particularly preferably 90 mass % to
100 mass %, when the total amount of the catalyst for monocyclic
aromatic hydrocarbon production is designated as 100 mass %. When
the content of the crystalline aluminosilicate is 60 mass % or
more, the yield of monocyclic aromatic hydrocarbons can be
sufficiently increased. Furthermore, the yield of naphthalene
compounds can also be raised to a relatively high level.
[0068] When the cracking reforming reaction step is carried out by
a fluidized bed reaction, the content of the crystalline
aluminosilicate in the catalyst for monocyclic aromatic hydrocarbon
production is preferably 20 mass % to 60 mass %, more preferably 30
mass % to 60 mass %, and particularly preferably 35 mass % to 60
mass %, when the total amount of the catalyst for monocyclic
aromatic hydrocarbon production is designated as 100 mass %. When
the content of the crystalline aluminosilicate is 20 mass % or
more, the yield of monocyclic aromatic hydrocarbons can be
sufficiently increased. Furthermore, the yield of naphthalene
compounds can also be raised to a relatively high level. Meanwhile,
when the content of the crystalline aluminosilicate is more than 60
mass %, the content of a binder that can be incorporated into the
catalyst is decreased, and the catalyst may not be suitable for
fluidized bed applications.
[0069] [Phosphorus and Boron]
[0070] The catalyst for monocyclic aromatic hydrocarbon production
preferably contains phosphorus and/or boron. When the catalyst for
monocyclic aromatic hydrocarbon production contains phosphorus
and/or boron, a decrease in the yield of monocyclic aromatic
hydrocarbons over time can be prevented, and coke production on the
catalyst surface can be suppressed.
[0071] Examples of the method for incorporating phosphorus to the
catalyst for monocyclic aromatic hydrocarbon production include a
method of supporting phosphorus on a crystalline aluminosilicate, a
crystalline aluminogallosilicate or a crystalline
aluminozincosilicate, by an ion exchange method, an impregnation
method or the like; a method of incorporating a phosphorus compound
at the time of zeolite synthesis and substituting a portion in the
skeleton of a crystalline aluminosilicate with phosphorus; and a
method of using a crystallization accelerator containing phosphorus
at the time of zeolite synthesis. The phosphate ion-containing
aqueous solution used at that time is not particularly limited, but
solutions prepared by dissolving phosphoric acid, diammonium
hydrogen phosphate, ammonium dihydrogen phosphate, and other
water-soluble phosphates in water at arbitrary concentrations can
be preferably used.
[0072] Examples of the method of incorporating boron into the
catalyst for monocyclic aromatic hydrocarbon production include a
method of supporting boron on a crystalline aluminosilicate, a
crystalline aluminogallosilicate or a crystalline
aluminozincosilicate, by an ion exchange method, an impregnation
method or the like; a method of incorporating a boron compound at
the time of zeolite synthesis and substituting a portion of the
skeleton of a crystalline aluminosilicate with boron; and a method
of using a crystallization accelerator containing boron at the time
of zeolite synthesis.
[0073] The content of phosphorus and/or boron in the catalyst for
monocyclic aromatic hydrocarbon production is preferably 0.1 mass %
to 10 mass %, relative to the total weight of the catalyst, and the
lower limit is more preferably 0.5 mass % or more, while the upper
limit is more preferably 9 mass % or less, and particularly
preferably 8 mass % or less. When the content of phosphorus and/or
boron relative to the total weight of the catalyst is 0.1 mass % or
more, a decrease in the yield of monocyclic aromatic hydrocarbons
over time can be prevented, and when the content is 10 mass % or
less, the yield of monocyclic aromatic hydrocarbons can be
increased.
[0074] [Gallium and Zinc]
[0075] In the catalyst for monocyclic aromatic hydrocarbon
production, gallium and/or zinc can be incorporated as necessary.
When gallium and/or zinc is incorporated, the production proportion
of monocyclic aromatic hydrocarbons can be further increased.
[0076] The form of gallium incorporation in the catalyst for
monocyclic aromatic hydrocarbon production may be a form in which
gallium is incorporated into the lattice skeleton of a crystalline
aluminosilicate (crystalline aluminogallosilicate), a form in which
gallium is supported on a crystalline aluminosilicate
(gallium-supporting crystalline aluminosilicate), or both of
them.
[0077] The form of zinc incorporation in the catalyst for
monocyclic aromatic hydrocarbon production may be a form in which
zinc is incorporated into the lattice skeleton of a crystalline
aluminosilicate (crystalline aluminozincosilicate), a form in which
zinc is supported on a crystalline aluminosilicate (zinc-supporting
crystalline aluminosilicate), or both of them.
[0078] The crystalline aluminogallosilicate and crystalline
aluminozincosilicate have a structure in which SiO.sub.4, AlO.sub.4
and GaO.sub.4/ZnO.sub.4 structures exist in the skeletal structure.
Furthermore, the crystalline aluminogallosilicate and crystalline
aluminozincosilicate are obtained by, for example, gel
crystallization based on hydrothermal synthesis, a method of
inserting gallium or zinc into the lattice skeleton of a
crystalline aluminosilicate, or a method of inserting aluminum into
the lattice skeleton of a crystalline gallosilicate or a
crystalline zincosilicate.
[0079] The gallium-supporting crystalline aluminosilicate is a
material in which gallium is supported on a crystalline
aluminosilicate according to a known method such as an ion exchange
method or an impregnation method. The gallium source that is used
at that time is not particularly limited, but examples thereof
include gallium salts such as gallium nitrate and gallium chloride,
and gallium oxide.
[0080] The zinc-supporting crystalline aluminosilicate is a
compound in which zinc is supported on a crystalline
aluminosilicate according to a known method such as an ion exchange
method or an impregnation method. The zinc source that is used at
that time is not particularly limited, but examples thereof include
zinc salts such as zinc nitrate and zinc chloride, and zinc
oxide.
[0081] When the catalyst for monocyclic aromatic hydrocarbon
production contains gallium and/or zinc, the content of gallium
and/or zinc in the catalyst for monocyclic aromatic hydrocarbon
production is preferably 0.01 mass % to 5.0 mass %, and more
preferably 0.05 mass % to 1.5 mass %, relative to 100 mass % of the
total amount of the catalyst. When the content of gallium and/or
zinc is 0.01 mass % or greater, the production proportion of
monocyclic aromatic hydrocarbons can be further increased. When the
content is 5.0 mass % or less, the yield of monocyclic aromatic
hydrocarbons can be further increased.
[0082] [Shape]
[0083] The catalyst for monocyclic aromatic hydrocarbon production
is produced into, for example, a powder form, a particulate form, a
pellet form or the like according to the reaction mode. For
example, in the case of a fluidized bed, the catalyst is produced
in a powder form, and in the case of a fixed bed, the catalyst is
produced in a particulate form or a pellet form. The average
particle size of the catalyst used in a fluidized bed is preferably
30 .mu.m to 180 .mu.m, and more preferably 50 .mu.m to 100 .mu.m.
Furthermore, the apparent density of the catalyst used in a
fluidized bed is preferably 0.4 g/cc to 1.8 glee, and more
preferably 0.5 g/cc to 1.0 g/cc.
[0084] Meanwhile, the average particle size represents the particle
size for a proportion of 50 mass % in a particle size distribution
obtained by classification using sieves, and the apparent density
is a value measured by the method of JIS Standards R9301-2-3.
[0085] In the case of obtaining a particulate or pellet-like
catalyst, an oxide which is inert to the catalyst is incorporated
as a binder as necessary, and the mixture may be molded by using
various molding machines.
[0086] When the catalyst for monocyclic aromatic hydrocarbon
production contains an inorganic oxide such as a binder, a binder
containing phosphorus may also be used.
[0087] (Reaction Temperature)
[0088] The reaction temperature at the time of bringing the
feedstock into contact with the catalyst for monocyclic aromatic
hydrocarbon production to react therewith is not particularly
limited, but the reaction temperature is preferably 400.degree. C.
to 650.degree. C., and more preferably 450.degree. C. to
650.degree. C. When the reaction temperature is 400.degree. C. or
higher, the reaction of the feedstock can be facilitated. When the
reaction temperature is from 450.degree. C. to 650.degree. C., the
yield of monocyclic aromatic hydrocarbons can be sufficiently
increased, and the yield of naphthalene compounds can also be
raised to a relatively high level.
[0089] (Reaction Pressure)
[0090] The reaction pressure employed when the feedstock is brought
into contact with the catalyst for monocyclic aromatic hydrocarbon
production to react therewith is preferably set to 1.5 MPaG or
less, and more preferably to 1.0 MPaG or less. When the reaction
pressure is 1.5 MPaG or less, by-production of light gas can be
suppressed, and also, pressure resistance of the reaction apparatus
can be lowered. Furthermore, when the reaction pressure is from 0.1
MPaG to 1.5 MPaG, the yield of monocyclic aromatic hydrocarbons can
be sufficiently increased, and the yield of naphthalene compounds
can also be raised to a relatively high level.
[0091] (Contact Time)
[0092] The contact time between the feedstock and the catalyst for
monocyclic aromatic hydrocarbon production is not particularly
limited so long as the desired reaction substantially proceeds.
However, for example, the time for gas passage on the catalyst for
monocyclic aromatic hydrocarbon production is preferably 1 second
to 300 seconds, and the lower limit is more preferably 5 seconds or
longer, while the upper limit is more preferably 150 seconds or
shorter. When the contact time is 1 second or longer, the reaction
can be achieved reliably, and when the contact time is 300 seconds
or shorter, accumulation of carbon substances on the catalyst
caused by coking or the like can be suppressed. Also, the amount of
light gas generated by cracking can be suppressed. Furthermore, the
yield of monocyclic aromatic hydrocarbons can be sufficiently
increased, and the yield of naphthalene compounds can also be
raised to a relatively high level.
[0093] <Separation Step>
[0094] In the separation step, the product produced in the cracking
reforming reaction step is separated into multiple fractions.
[0095] In order to separate the product into plural fractions,
known distillation apparatuses and gas-liquid separation
apparatuses may be used. Examples of the distillation apparatuses
include apparatuses that are capable of separating by distillation
of multiple fractions by a multistage distillation apparatus such
as a stripper. Examples of the gas-liquid separation apparatuses
include apparatuses each equipped with a gas-liquid separating
tank, a product inlet pipe for introducing the product into the
gas-liquid separating tank, a gas component discharge pipe provided
in the upper part of the gas-liquid separating tank, and a liquid
component discharge pipe provided in the lower part of the gas
liquid separating tank.
[0096] In the separation step, it is preferable to separate at
least gas components and a liquid fraction, and the liquid fraction
may be further separated into plural fractions. An example of the
separation step may be a form of process by which the reaction
product is separated into gas components mainly including
components having 4 or fewer carbon numbers (for example, hydrogen,
methane, ethane, and LPG) and a liquid fraction. Furthermore,
another example of the separation step may be a form of process by
which the reaction product is separated into gas components
including components having 2 or fewer carbon numbers (for example,
hydrogen, methane and ethane) and a liquid fraction. Furthermore,
another example of the separation step may be a form of process by
which the liquid fraction is separated into LPG, a fraction
containing monocyclic aromatic hydrocarbons, and a heavy oil
fraction. Furthermore, another example of the separation step may
be a form of process by which the liquid fraction is separated into
LPG (for example, propylene, propane, butene, and butane), a
fraction containing monocyclic aromatic hydrocarbons, and plural
heavy oil fractions. Furthermore, when a fluidized bed is employed
as the reaction mode for the cracking reforming reaction step, the
catalyst powder and the like to be incorporated may be removed in
the present step. However, for the heavy oil fraction, naphthalene
compounds may be separated singly, or the heavy oil fraction may
also be collectively fractionated without separating into plural
fractions. The boiling point range of the fraction containing
monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers is
preferably 78.degree. C. to 150.degree. C., and the boiling point
range of the heavy oil fraction primarily containing naphthalene
compounds is preferably 210.degree. C. to 270.degree. C.
[0097] <Purification and Collection Step>
[0098] The purification and collection step purifies and collects
the monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers
obtained in the separation step.
[0099] In this purification and collection step, the liquid
fraction is sufficiently fractionated in the separation step, and
when monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers
are separated into benzene/toluene/xylene, a step of purifying and
collecting the respective components is employed. Furthermore, when
the monocyclic aromatic hydrocarbons having 6 to 8 carbon numbers
are collectively fractionated, a step of collecting these
monocyclic aromatic hydrocarbons, subsequently separating the
hydrocarbons into benzene/toluene/xylene, and then purifying and
collecting the respective components is employed.
[0100] In the case where the liquid fraction is not satisfactorily
fractionated in the separation step, and when the monocyclic
aromatic hydrocarbons having 6 to 8 carbon numbers are collected,
the liquid fraction contains a large proportion of a fraction other
than the monocyclic aromatic hydrocarbons, these fractions may be
separated and supplied to, for example, the hydrogenation reaction
step or naphthalene collection step that will be described below.
Particularly, among the fractions other than monocyclic aromatic
hydrocarbons, a fraction heavier than the monocyclic aromatic
hydrocarbons (a heavy oil fraction having 9 or more carbon numbers)
is preferably supplied to the naphthalene collection step. This is
because the heavy oil fraction having 9 or more carbon numbers
contains polycyclic aromatic hydrocarbons as a main component, and
contains a large proportion of naphthalene or alkylnaphthalenes in
particular.
[0101] Naphthalene Collecting Step>
[0102] In the naphthalene collecting step, naphthalene compounds
including at least naphthalene are separated and collected from a
heavy oil fraction having 9 or more carbon numbers obtainable from
the liquid fraction separated in the separation step.
[0103] In this naphthalene collecting step, in the case where the
heavy oil fraction separated in the separation step is separated
into a heavy oil fraction primarily containing naphthalene
compounds in particular and a heavy oil fraction other than that,
the heavy oil fraction containing naphthalene compounds is
purified, and thus naphthalene compounds are separated and
collected. Furthermore, in the separation step, when the heavy oil
fraction having 9 or more carbon numbers is collectively
fractionated without dividing the heavy oil fraction having 9 or
more carbon numbers into plural fractions, the heavy oil fraction
is separated into a fraction containing naphthalene compounds,
specifically naphthalene compounds including naphthalene,
methylnaphthalene and dimethylnapthalene, and a fraction other than
that, and the naphthalene compounds including at least naphthalene
are purified and collected.
[0104] Meanwhile, in order to separate the heavy oil fraction into
multiple fractions, a known distillation apparatus (distillation
column) such as that used in the separation step may be used.
[0105] Since the components having a boiling point close to that of
the naphthalene compounds in the oil produced by a cracking
reforming reaction have been reduced to a large extent by going
through the cracking reforming reaction step, in the present
naphthalene collecting step, naphthalene can be separated with high
purity, purified and collected by using only a known distillation
apparatus such as that used in the separation step. For example,
naphthalene can be purified to a purity of about 80% to 98% and
then can be collected. Meanwhile, the purity of naphthalene thus
collected is determined on the basis of reduction of the number and
the production amount of components having a boiling point close to
that of naphthalene that remains in the cracking reforming reaction
step, and the performance of the distillation apparatus. When
naphthalene is collected with a purity of 95% or higher, the
naphthalene can be dealt with as a product which is generally
distributed as crude naphthalene and has a commercial value, and in
regard to naphthalene with a purity of less than 95%, for example,
about 80% to 95%, this can be made into crude naphthalene as a
chemical product by performing a purification treatment later and
increasing the purity to 95% or higher. Furthermore, a fraction
having a purity of 95% or higher can also be subjected to a further
purification treatment and can be converted to naphthalene with
higher purity. Examples of the purification treatment methods in
this case include crystallization.
[0106] In the naphthalene collecting step, so long as naphthalene
can be separated and collected, naphthalene compounds other than
naphthalene may be collectively separated, purified and collected
as alkylnaphthalenes, or may be individually separated, purified
and collected as methylnaphthalene, dimethylnaphthalene and the
like. In this case, methylnaphthalene and dimethylnaphthalene are
respectively purified to a purity of about 80% to 95% and
collected. Thereafter, the components are respectively purified to
a purity demanded as chemical products.
[0107] Here, in this naphthalene collecting step, a fraction other
than the desired naphthalene, methylnaphthalene and
dimethylnaphthalene is also obtained. This fraction is sent out of
the system, and for example, after treatments such as purification
are carried out as necessary, the fraction is used as a base
material for light oil/kerosene. Alternatively, the fraction is
sent to the hydrogenation reaction step that will be described
below, and after this step, the fraction is recycled.
[0108] Meanwhile, in the present embodiment shown in FIG. 1, the
naphthalene collecting step is composed of a single step. In the
naphthalene collecting step, first, the step may be divided into
multiple steps by providing a step of separating and collecting
naphthalene from a heavy oil fraction having 9 or more carbon
numbers, and then providing steps of respectively fractionating and
collecting methylnaphthalene, dimethylnaphthalene and the like, and
naphthalene, methylnaphthalene and dimethylnaphthalene may be
respectively fractionated and collected. Furthermore, a fraction
other than these is used as a base material for light oil/kerosene,
or is subjected to a hydrogenation reaction step or the like and
then supplied to the feedstock for recycling.
[0109] <Hydrogenation Reaction Step>
[0110] In this hydrogenation reaction step, a portion or the
entirety of the remaining fraction obtained after naphthalene has
been separated in the naphthalene collecting step is supplied to
this hydrogenation reaction step, and this fraction is
hydrogenated. Here, if only naphthalene is separated and collected
in the naphthalene collecting step, and alkylnaphthalenes such as
methylnaphthalene and dimethylnaphthalene are not separated and
collected, these alkylnaphthalenes constitute the "remaining
fraction obtained after naphthalene has been separated" as
described above, and are supplied to the hydrogenation reaction
step. Meanwhile, the remaining fraction obtained after naphthalene
compounds have been separated, which was not supplied to the
hydrogenation reaction step, may also be used as a fuel base
material for light oil/kerosene and the like.
[0111] Specifically, the remaining fraction obtained by naphthalene
compounds have been separated in the naphthalene collecting step,
and hydrogen are supplied to a hydrogenation reactor, and at least
a portion of the polycyclic aromatic hydrocarbons included in the
remaining fraction obtained after naphthalene compounds have been
separated is subjected to hydrogenation by using a hydrogenation
catalyst.
[0112] The polycyclic aromatic hydrocarbons are not particularly
limited, but it is preferable to hydrogenate the polycyclic
aromatic hydrocarbons until the number of aromatic rings becomes 1
or less on the average. When the polycyclic aromatic hydrocarbons
are hydrogenated until the number of aromatic rings becomes 1 or
less on the average, when the polycyclic aromatic hydrocarbons are
recycled to the cracking reforming reaction step, the hydrogenation
reaction product can be easily converted to monocyclic aromatic
hydrocarbons.
[0113] Furthermore, in order to further increase particularly the
yield of monocyclic aromatic hydrocarbons, the content of
polycyclic aromatic hydrocarbons in the hydrogenation reaction
product obtainable in the hydrogenation reaction step is preferably
adjusted to 20 mass % or less, and more preferably 10 mass % or
less. The content of polycyclic aromatic hydrocarbons in the
hydrogenation reaction product is preferably smaller than the
content of polycyclic aromatic hydrocarbons in the feedstock, and
the content can be reduced as the amount of the hydrogenation
catalyst is increased, and as the reaction pressure is
increased.
[0114] However, it is not necessary to carry out the hydrogenation
treatment until the entirety of the polycyclic aromatic
hydrocarbons becomes saturated hydrocarbons. Excessive
hydrogenation tends to cause an increase in the amount of hydrogen
consumption and an increase in the amount of heat generation.
[0115] Furthermore, when it is intended to prioritize an
enhancement of the yield of naphthalene (naphthalene compounds) to
an enhancement of the yield of monocyclic aromatic hydrocarbons,
the content of polycyclic aromatic hydrocarbons in the
hydrogenation reaction product obtainable in the hydrogenation
reaction step is preferably adjusted to 20 mass % or more.
[0116] In the present embodiment, hydrogen produced as a by-product
in the cracking reforming reaction step can also be utilized. That
is, hydrogen is collected in the hydrogenation collecting step that
will be described below from the gas components obtained in the
separation step, and in the hydrogen supply step, the collected
hydrogen is supplied to the hydrogenation reaction step.
[0117] Regarding the reaction mode for the hydrogenation reaction
step, a fixed bed is suitably employed.
[0118] As the hydrogenation catalyst, known hydrogenation catalysts
(for example, a nickel catalyst, a palladium catalyst, a
nickel-molybdenum-based catalyst, a cobalt-molybdenum-based
catalyst, a nickel-cobalt-molybdenum-based catalyst, and a
nickel-tungsten-based catalyst) can be used.
[0119] The reaction temperature may vary depending on the
hydrogenation catalyst used, but the reaction temperature is
usually set to the range of 100.degree. C. to 450.degree. C., more
preferably 200.degree. C. to 400.degree. C., and even more
preferably 250.degree. C. to 380.degree. C.
[0120] The reaction pressure may vary depending on the
hydrogenation catalyst or feedstock used, but the reaction pressure
is preferably set to the range of 0.7 MPa to 13 MPa, more
preferably set to 1 MPa to 10 MPa, and particularly preferably set
to 1 MPa to 7 MPa. When the reaction pressure is adjusted to 13 MPa
or less, a hydrogenation reactor having a low durability pressure
can be used, and the cost of equipment can be reduced.
[0121] On the other hand, the reaction pressure is preferably 0.7
MPa or greater in view of the yield of the hydrogenation
reaction.
[0122] The amount of hydrogen consumption is preferably 3000 scfb
(506 Nm.sup.3/m.sup.3) or less, more preferably 2500 scfb (422
Nm.sup.3/m.sup.3) or less, and even more preferably 1500 scfb (253
Nm.sup.3/m.sup.3) or less.
[0123] On the other hand, the amount of hydrogen consumption is
preferably 300 scfb (50 Nm.sup.3/m.sup.3) or greater in view of the
yield of the hydrogenation reaction.
[0124] The liquid hourly space velocity (LHSV) is preferably set to
from 0.1 h.sup.-1 to 20 h.sup.-1, and more preferably set to from
0.2 h.sup.-1 to 10 h.sup.-1. When the LHSV is set to 20 h.sup.-1 or
less, polycyclic aromatic hydrocarbons can be sufficiently
hydrogenated at a lower hydrogenation reaction pressure. On the
other hand, when the LHSV is set to 0.1 h.sup.-1 or higher, an
excessive increase in the size of hydrogenation reactors can be
avoided.
[0125] <Hydrogen Collecting Step>
[0126] In the hydrogen collecting step, hydrogen is collected from
the gas components obtained in the separation step.
[0127] Regarding the method for collecting hydrogen, there are no
particular limitations so long as hydrogen and other gases that are
included in the gas components obtained in the separation step can
be separated, and examples thereof include a pressure swing
adsorption method (PSA method), a low temperature separation
processing method, and a membrane separation method.
[0128] Conventionally, the amount of hydrogen collected in the
hydrogen collecting step is larger than the amount required for
hydrogenating the heavy oil fraction or the light oil/kerosene
fraction described above.
[0129] <Hydrogen Supply Step>
[0130] In the hydrogen supply step, hydrogen obtained in the
hydrogen collecting step is supplied to the hydrogenation reactor
of the hydrogenation reaction step. The amount of hydrogen supplied
at that time is adjusted according to the amount of the remaining
fraction obtained after naphthalene compounds have been separated
in the naphthalene collecting step, which is supplied to the
hydrogenation reaction step. Furthermore, if necessary, the
hydrogen pressure is regulated.
[0131] By including such a hydrogen supply step as that of the
present embodiment, the remaining fraction obtained after
naphthalene compounds have been separated in the naphthalene
collecting step described above can be hydrogenated by using the
hydrogen produced as a by-product in the cracking reforming
reaction step, and efficient operation of the apparatus can be
promoted.
[0132] <Recycling Step>
[0133] In the recycling step, the hydrogenation reaction product is
mixed with the feedstock, and the mixture is recycled to the
cracking reforming reaction step. The hydrogenation reaction
product is a product obtained by allowing the remaining fraction
obtained after naphthalene compounds have been separated in the
naphthalene collecting step, to react in the hydrogenation reaction
step.
[0134] When such a hydrogenation reaction product is recycled to
the cracking reforming reaction step, monocyclic aromatic
hydrocarbons or naphthalene compounds can be obtained by using the
heavy oil fraction (excluding naphthalene compounds), which is a
by-product, as a feedstock. Therefore, not only the amount of
by-product can be reduced, but also, the amount of monocyclic
aromatic hydrocarbons or naphthalene compounds produced can be
increased. Furthermore, since saturated hydrocarbons are also
produced by hydrogenation, the hydrogen transfer reaction can be
accelerated in the cracking reforming reaction step. From these
matters, the general yield of monocyclic aromatic hydrocarbons
relative to the amount of the feedstock supplied can be increased,
and also, the yield of naphthalene compounds can also be
increased.
[0135] Meanwhile, when the remaining fraction obtained by
separating naphthalene compounds in the naphthalene collecting step
is recycled directly to the cracking reforming reaction step
without performing a hydrogenation treatment, since the reactivity
of polycyclic aromatic hydrocarbons is low, an increase in the
yield of monocyclic aromatic hydrocarbons can be hardly expected.
However, an increase in the yield of naphthalene compounds can be
promoted.
[0136] <LPG Collecting Step>
[0137] In the LPG collecting step, LPG that is produced as a
by-product in the cracking reforming reaction step is collected
from the liquid fraction separated in the separation step.
[0138] In this LPG collecting step, a liquid fraction having 3 or 4
carbon numbers, that is, propylene, propane, butene and butane are
purified and collected as LPG. In the oil produced by the cracking
reforming reaction in the method for producing aromatic
hydrocarbons of the present embodiment, unlike the products of
hydrogenation cracking and the like in conventional petroleum
purification processes, more of olefins such as propylene and
butene are present. Therefore, if necessary, collection of olefins
by hydrogenation or rectification can also be achieved.
[0139] As explained above, in the method for producing aromatic
hydrocarbons of the present embodiment, monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers can be produced with a
relatively high yield from a feedstock containing polycyclic
aromatic hydrocarbons, and as other chemical products, naphthalene
compounds including naphthalene, or olefin compounds such as
propylene, propane, butene and butane can also be produced.
[0140] Particularly, in regard to naphthalene, it has been
conventional in general to produce naphthalene according to a
crystallization method by which coal tar distillate oil is cooled,
and thereby crystals are precipitated. However, the crystallization
method requires complicated steps, and there is a problem that the
production cost is high.
[0141] In contrast to this, the method for producing aromatic
hydrocarbons of the present embodiment can obtain naphthalene with
a relatively high purity, only by adding a naphthalene collecting
step, or if necessary, a naphthalene compound separation and
collection step to the process for producing monocyclic aromatic
hydrocarbons having 6 to 8 carbon numbers. Therefore, in regard to
the production cost for naphthalene (or naphthalene compounds),
when the portion for producing monocyclic aromatic hydrocarbons
having 6 to 8 carbon numbers is deducted, the production cost is
markedly decreased as compared with conventional methods according
to a crystallization method. Therefore, naphthalene (or naphthalene
compounds) can be provided at low cost.
Other Embodiments
[0142] The invention is not intended to be limited to the
embodiment examples described above, and various modifications can
be made to the extent that the gist of the invention is
maintained.
[0143] For example, in regard to the method shown in FIG. 1, a
hydrogenation reaction step of hydrogenating a portion of the
liquid components separated in the separation process may be
provided between the separation process and the purification and
collection process. In the purification and collection step, the
hydrogenation reaction product obtained in the hydrogenation
reaction step may be distilled, and monocyclic aromatic
hydrocarbons may be purified and collected.
[0144] Furthermore, a portion of the heavy oil fraction separated
in the separation step may also be supplied to the hydrogenation
reaction step without going through the naphthalene collecting
step, and the portion may also be hydrogenated and recycled to the
cracking reforming reaction process.
[0145] Furthermore, in these methods or in the method shown in FIG.
1, regarding hydrogen used in the hydrogenation reaction step,
hydrogen obtained in a known hydrogen production method may be used
instead of the hydrogen produced as a by-product in the cracking
reforming reaction step, or hydrogen produced as a by-product in
another contact cracking method may also be used.
EXAMPLES
[0146] Hereinafter, the invention will be more specifically
described based on Examples and Comparative Examples, but the
invention is not intended to be limited by these Examples.
[0147] [Preparation Example for Catalyst for Monocyclic Aromatic
Hydrocarbon Production]
[0148] Preparation of Catalyst Containing Ga and
Phosphorus-Supported Crystalline Aluminosilicate:
[0149] A solution (A) containing sodium silicate (J sodium silicate
No. 3, SiO.sub.2: 28 mass % to 30 mass %, Na: 9 mass % to 10 mass
%, balance water, manufactured by Nippon Chemical Industrial Co.,
Ltd.): 1706.1 g and water: 2227.5 g, and a solution (B) containing
Al.sub.2(SO.sub.4).sub.3.14-18H.sub.2O (reagent grade, manufactured
by Wako Pure Chemical Industries, Ltd.): 64.2 g,
tetrapropylammonium bromide: 369.2 g, H.sub.2SO.sub.4 (97 mass %):
152.1 g, NaCl: 326.6 g and water: 2975.7 g were each prepared.
[0150] Subsequently, while the solution (A) was stirred at room
temperature, the solution (B) was slowly added to the solution
(A).
[0151] The mixture thus obtained was vigorously stirred for 15
minutes in a mixer, and the gel was crushed to obtain a milky
homogenously fine state.
[0152] Subsequently, this mixture was placed in an autoclave made
of stainless steel, and a crystallization operation was carried out
under self-pressure under the conditions of a temperature of
165.degree. C., a time of 72 hours, and a stirring speed of 100
rpm. After completion of the crystallization operation, the product
was filtered to collect a solid product, and washing and filtration
was repeated 5 times by using about 5 liters of deionized water.
The solid obtained by filtration was dried at 120.degree. C., and
the solid was calcined at 550.degree. C. for 3 hours under a stream
of air.
[0153] It was confirmed by an X-ray diffraction analysis (model
name: Rigaku. RINT-2500V) that the calcination product thus
obtained had an MFI structure. Furthermore, the
SiO.sub.2/Al.sub.2O.sub.3 ratio (molar ratio) obtained by a
fluorescence X-ray analysis (model name: Rigaku ZSX101e) was 64.8.
Furthermore, the content of the aluminum element contained in the
lattice structure calculated from these results was 1.32 mass
%.
[0154] Subsequently, a 30 mass % aqueous solution of ammonium
nitrate was added at a ratio of 5 mL per 1 g of the calcination
product thus obtained, and the mixture was heated and stirred at
100.degree. C. for 2 hours, subsequently filtered and washed with
water. This operation was repeated 4 times, and then the mixture
was dried at 120.degree. C. for 3 hours. Thus, an ammonium type
crystalline aluminosilicate was obtained.
[0155] Thereafter, calcination was carried out for 3 hours at
780.degree. C., and thus a proton type crystalline aluminosilicate
was obtained.
[0156] Subsequently, 120 g of the proton type crystalline
aluminosilicate thus obtained was impregnated with 120 g of an
aqueous solution of gallium nitrate such that 0.4 mass % (a value
calculated relative to 100 mass % of the total mass of the
crystalline aluminosilicate) of gallium would be supported, and the
resultant was dried at 120.degree. C. Thereafter, the product was
calcined at 780.degree. C. for 3 hours under an air stream, and
thus a gallium-supported crystalline aluminosilicate was
obtained.
[0157] Subsequently, 30 g of the gallium-supported crystalline
aluminosilicate thus obtained was impregnated with 30 g of an
aqueous solution of diammonium hydrogen phosphate such that 0.7
mass % of phosphorus (a value calculated relative to 100 mass % of
the total mass of the crystalline aluminosilicate) would be
supported, and the resultant was dried at 120.degree. C.
Thereafter, the product was calcined at 780.degree. C. for 3 hours
under an air stream, and thus a catalyst A containing a crystalline
aluminosilicate, gallium and phosphorus was obtained.
[0158] Meanwhile, when the production of monocyclic aromatic
hydrocarbons is carried out in a fluidized bed reaction mode, the
catalyst A further contains a silica binder (the content of the
silica binder is 60 mass % relative to the total mass of the
catalyst) in addition to the crystalline aluminosilicate, gallium
and phosphorus.
Example 1
[0159] LCO as indicated in Table 1 (10 vol % distillation
temperature: 224.5.degree. C., 90 vol % distillation temperature:
349.5.degree. C.), which was a feedstock, was brought into contact
with the catalyst A (a catalyst produced by incorporating a silica
binder to an MFI type zeolite supporting 0.4 mass % of gallium and
0.7 mass % of phosphorus, in an amount of 60 mass % relative to the
total mass of the catalyst) in a fluidized bed reactor under the
conditions of a reaction temperature of 550.degree. C., a reaction
pressure of 0.1 MPaG, and a contact time of 30 seconds, and was
allowed to react therewith, and thus production of monocyclic
aromatic hydrocarbons was carried out.
[0160] The reaction product oil thus obtained was analyzed by an
FID gas chromatographic method, and the amount of impurities
between durene (boiling point: 196.degree. C.) and naphthalene
(boiling point: 218.degree. C.) was 1.9 mass % relative to 100 of
naphthalene. Furthermore, the amount of impurities between
naphthalene and 2-methylnaphthalene (boiling point: 241.degree. C.)
was 0.6 mass % relative to 100 of naphthalene, and 0.4 mass %
relative to 100 of methylnaphthalene. Thus, it was found that there
were very few components having a boiling point close to that of
naphthalene.
[0161] Subsequently, the reaction product oil thus obtained was
fractionated in a rectifying column into a gas fraction, a fraction
containing monocyclic aromatic hydrocarbons (benzene, toluene and
xylene), and a heavy oil fraction having 9 or more carbon numbers
(heavy oil fraction 1).
[0162] The heavy oil fraction 1 was further distilled in the
rectifying column, and was fractionated into a fraction mainly
containing naphthalene (boiling point: 218.degree. C.) and a
fraction other than naphthalene (heavy oil fraction 2).
[0163] The yield of the monocyclic aromatic hydrocarbons (benzene,
toluene, and crude xylene (xylene including a small amount of
ethylbenzene and the like)) obtained by fractionation was 30 mass
%, and the yield of the naphthalene fraction was 7 mass %.
Meanwhile, the naphthalene purity in the naphthalene fraction was
96 mass %.
TABLE-US-00001 TABLE 1 Analysis Feedstock characteristics method
Density @ 15.degree. C. g/cm.sup.3 0.906 JIS K 2249 Dynamic
viscosity @ 30.degree. C. mm.sup.2/s 3.640 JIS K 2283 Distillate
Initial boiling point .degree. C. 175.5 JIS K 2254 characteristics
10 vol % distillation temperature .degree. C. 224.5 50 vol %
distillation temperature .degree. C. 274.0 90 vol % distillation
temperature .degree. C. 349.5 End point .degree. C. 376.0
Composition Saturated content vol % 35 JPI-5S-49 analysis Olefin
content vol % 8 Total aromatic content vol % 57 Monocyclic aromatic
content vol % 23 Bicyclic aromatic content vol % 25 Tricyclic or
higher-cyclic aromatic vol % 9 content
Example 2
[0164] LCO as indicated in Table 1 (10 vol % distillation
temperature: 224.5.degree. C., 90 vol % distillation temperature:
349.5.degree. C.), which was a feedstock, was brought into contact
with the catalyst A (an MFI type zeolite supporting 0.4 mass % of
gallium and 0.7 mass % of phosphorus) in a fixed bed reactor under
the conditions of a reaction temperature of 550.degree. C., a
reaction pressure of 0.3 MPaG, and a contact time of 18 seconds,
and was allowed to react therewith, and thus production of
monocyclic aromatic hydrocarbons was carried out.
[0165] The reaction product oil thus obtained was analyzed by an
FID gas chromatographic method, and the amount of impurities
between durene (boiling point: 196.degree. C.) and naphthalene
(boiling point: 218.degree. C.) was 2.4 mass % relative to 100 of
naphthalene. Furthermore, the amount of impurities between
naphthalene and 2-methylnaphthalene (boiling point: 241.degree. C.)
was 1.6 mass % relative to 100 of naphthalene, and 0.9 mass %
relative to 100 of methylnaphthalene. Thus, it was found that there
were very few components having a boiling point close to that of
naphthalene.
[0166] Subsequently, the reaction product oil thus obtained was
fractionated in a rectifying column into a gas fraction, a fraction
containing monocyclic aromatic hydrocarbons (benzene, toluene and
crude xylene), and a heavy oil fraction having 9 or more carbon
numbers.
[0167] The heavy oil fraction having 9 or more carbon numbers was
further distilled in the rectifying column, and was fractionated
into a fraction mainly containing naphthalene (boiling point:
218.degree. C.) and a fraction other than naphthalene.
[0168] The yield of the monocyclic aromatic hydrocarbons (benzene,
toluene, and crude xylene) obtained by fractionation was 37 mass %,
and the yield of the naphthalene fraction was 9 mass %. Meanwhile,
the naphthalene purity in the naphthalene fraction was 95 mass
%.
Example 3
[0169] The fraction other than naphthalene (heavy oil fraction 2:
content of polycyclic aromatic hydrocarbons is 95 mass % or more)
obtained in Example 1 was subjected to a hydrogenation reaction by
using a commercially available nickel-molybdenum catalyst under the
conditions of a reaction temperature of 350.degree. C. and a
reaction pressure of 5 MPaG. The hydrogenation reaction product
thus obtained was 69 mass % of hydrocarbon compounds having one
aromatic ring, and 28 mass % of compounds having two or more
aromatic rings (polycyclic aromatic hydrocarbons). Thus, compared
to the fraction before the hydrogenation reaction, the content of
polycyclic aromatic hydrocarbons was reduced to a large extent.
[0170] Subsequently, a feedstock obtained by recycling the
hydrogenation reaction product into the LCO indicated in Table 1 in
an amount of 0.4 times the mass of LCO, was brought into contact
with the catalyst A (a catalyst produced by incorporating a silica
binder to an MFI type zeolite supporting 0.4 mass % of gallium and
0.7 mass % of phosphorus, in an amount of 60 mass % relative to the
total mass of the catalyst) in a fluidized bed reactor under the
conditions of a reaction temperature of 550.degree. C., a reaction
pressure of 0.3 MPaG, and a contact time of 30 seconds, and was
allowed to react therewith, and thus production of monocyclic
aromatic hydrocarbons was carried out.
[0171] The yield of monocyclic aromatic hydrocarbons (benzene,
toluene and crude xylene) thus obtained was 36 mass %, and as
compared with Example 1 in which the hydrogenation reaction product
was not recycled, an increase in the yield of monocyclic aromatic
hydrocarbons was observed.
[0172] From the results of Examples 1 to 3, it was found that
according to the method for producing aromatic hydrocarbons related
to the invention, monocyclic aromatic hydrocarbons having 6 to 8
carbon numbers including benzene, toluene and crude xylene are
obtained with high yield, and naphthalene of high purity (90 mass %
or higher) can be produced.
INDUSTRIAL APPLICABILITY
[0173] According to the method for producing aromatic hydrocarbons
of the present invention, not only monocyclic aromatic hydrocarbons
having 6 to 8 carbon numbers but also naphthalene compounds
including naphthalene can all be produced by using an oil
containing polycyclic aromatic hydrocarbons such as LCO.
* * * * *