DESCRIPTION
METHOD FOR PRODUCING ALUMINOSILICATE CATALYST,
ALUMINOSILICATE CATALYST, AND METHOD FOR PRODUCING
MONOCYCLIC AROMA TIC HYDROCARBONS
TECHNICAL FIELD
[0001]
The present invention relates to a method for producing an aluminosilicate
catalyst, an aluminosilicate catalyst, and a method for producing monocyclic aromatic
hydrocarbons having a carbon number of 6 to 8.
Priority is claimed on Japanese Patent Application No. 2014-078010, filed April
4, 2014, the content of which is incorporated herein by reference.
BACKGROUND ART
[0002]
In recent years, technology has been proposed that enables the efficient
production of monocyclic aromatic hydrocarbons having a carbon number of 6 to 8 (such
as benzene, toluene and crude xylene, which are hereafter jointly referred to as "BTX"),
which can be used as high-octane gasoline base stocks or petrochemical feedstocks and
offer significant added value, from feedstock oils containing a polycyclic aromatic
hydrocarbon fraction such as light cycle oil (hereafter also referred to as "LCO"), which
is a cracked light oil produced in a fluid catalytic cracking (hereafter also referred to as
"FCC") apparatus.
[0003]
2
One example of a known method for producing BTX from a polycyclic aromatic
fraction is a method in which a feedstock oil is brought into contact with a catalyst, and a
cracking and reforming reaction is induced to obtain a product containing monocyclic
aromatic hydrocarbons having a carbon number of 6 to 8.
Known reaction systems for conducting the cracking and reforming reaction
include various processes such as fixed bed, fluidized bed and moving bed systems, but a
fixed bed system is advantageous for reasons including inexpensive construction costs
and operating costs.
[0004]
When a process such as the aforementioned cracking and reforming reaction is
conducted to produce monocyclic aromatic hydrocarbons, a zeolite catalyst having acid
sites (a crystalline aluminosilicate catalyst) is typically used as the catalyst. At the
laboratory level, this type of zeolite catalyst is able to maintain its performance in a
favorable state, and is therefore typically used as is, without adding a binder. However,
in a fixed bed reaction tower, particularly at the level of an actual production plant, in
order to compensat~ for a lack of strength, a binder is used to create a molded catalyst,
despite this causing a slight deterioration in the catalyst performance.
[0005]
In other words, in order to ensure that the catalyst does not create obstacles to
operation, for example due to the catalyst powdering during operation and disturbing the
flow of the oil tlll'ough the reaction tower, or due to the powdered catalyst frequently
blocking the filter provided at the outlet of the reaction tower, a molded zeolite catalyst
prepared using a binder or the like is often used ..
[0006]
3
Examples of this type of zeolite catalyst that has been molded using a binder
include the catalyst disclosed in Patent Document I. The zeolite catalyst disclosed in
Patent Document I is used for alkylating mainly aromatic compounds, such as the
methylation of toluene, and is formed by treating a zeolite with a phosphorus compound
to form a phosphorus-treated zeolite, heating the phosphorus-treated zeolite at a
temperature of300°C to 400°C, mixing the heated phosphorus-treated zeolite with an
alumina-containing binder to form a zeolite-binder mixture, and then heating the zeolitebinder
mixture at a temperature of 400°C or higher.
PRIOR ART LITERATURE
Patent Documents
[0007]
Patent Document I: Japanese Patent No. 5,254, 789
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
[0008]
However, with zeolite catalysts having an added binder, significant coke
formation occurs due to the acid sites within the binder. When coke formation becomes
more significant in this manner, it is necessary to shorten the catalyst "reactionregeneration"
cycle, particularly in the case of fixed beds, and therefore the operating
costs increase and the merits of using a fixed bed tend to diminish. Further, frequent
repetition of the regeneration process tends to cause a reduction in the number of acid
sites within the aluminosilicate catalyst due to hydrothermal degradation, resulting in a
4
reduction in the activity of the catalyst itself, which is.undesirablc from the viewpoint of
the catalyst lifespan.
[0009]
The present invention has been developed in light of the above circumstances,
and has an object of providing a method for producing an aluminosilicate catalyst in
which by suppressing coke formation and suppressing hydrothermal degradation of the
catalyst itself, any deterioration in the activity of the zeolite catalyst can be suppressed,
and the hydrothermal stability can be enhanced, as well as providing a method for
producing monocyclic aromatic hydrocarbons having a carbon number of 6 to 8 using
this aluminosilicate catalyst.
Means for Solving the Problems
[0010]
A method for producing an aluminosilicate catalyst according to one aspect of the
present invention has a first phosphotus treatment step of treating a crystalline
aluminosilicate with a first phosphorus compound, a mixing and firing step of mixing the
phosphoms-treated crystalline aluminosilicate obtained in the first phosphorus treatment
step with a binder, and then performing firing to form an aluminosilicate mixture, and a
second phosphorus treatment step of treating the aluminosilicate mixture with a second
phosphorus compound.
[0011]
Fmther, in the above method for producing an aluminosilicate catalyst, in the
mixing and firing step, the phosphorus-treated crystalline aluminosilicate and the binder
may be mixed and molded, and the thus obtained molded body then fired.
5
Fmihennore, in the above method for producing an aluminosilicate catalyst, the
crystalline aluminosilicate may contain at least one component selected from the group
consisting of medium pore zeolites and large pore zeolites as the main component.
Further, in the above method for producing an aluminosilicate catalyst, the
crystalline aluminosilicate may be a pentasil zeolite.
Furthermore, in the above method for producing an aluminosilicate catalyst, the
crystalline aluminosilicate may be an MFI zeolite.
Further, in the above method for producing an aluminosilicate catalyst, the binder
may contain alumina.
Fmihermore, in the above method for producing an aluminosilicate catalyst,
phosphoric acid may be used as the second phosphorus compound.
Further, in the above method for producing an aluminosilicate catalyst, following
the second phosphorus treatment step, a heat treatment may be performed in an
atmosphere containing water vapor.
[0012]
An aluminosilicate catalyst according to another aspect of the present invention is
obtained using the above method for producing an aluminosilicate catalyst.
[0013]
A method for producing monocyclic aromatic hydrocarbons having a carbon
number of 6 to 8 according to yet another aspect of the present invention has a cracking
and reforming reaction step of bringing a feedstock oil having a 10 vol% distillation
temperature of at least 140°C and a 90 vol% distillation temperature of not more than
390°C into contact with a monocyclic aromatic hydrocarbon production catalyst
containing the above aluminosilicate catalyst packed in a fixed bed reactor, and reacting
-,
6
the feedstock oil to obtain a product containing monocyclic aromatic hydrocarbons
having a carbon number of 6 to 8.
[0014]
Further, in the above method for producing monocyclic aromatic hydrocarbons
having a carbon number of 6 to 8, in the cracking and reforming reaction step, two or
more fixed bed reactors may be used, and the cracking and reforming reaction and
regeneration of the monocyclic aromatic hydrocarbon production catalyst may be
repeated while periodically exchanging the fixed bed reactors.
Fmther, in the above method for producing monocyclic aromatic hydrocarbons
having a carbon number of 6 to 8, the feedstock oil may be a light cycle oil or a partially
hydrogenated product of the light cycle oil.
Furthermore, in the above method for producing monocyclic aromatic
hydrocarbons having a carbon number of 6 to 8, the feedstock oil may be a thermally
cracked heavy oil obtained from an ethylene production apparatus or a partially
hydrogenated product of the thermally cracked heavy oil.
Effects of the Invention
[0015]
The method for producing an aluminosilicate catalyst according to one aspect of
the present invention enables the production of an aluminosilicate catalyst which
suppresses coke formation and for which any deterioration in the activity of the catalyst
is suppressed.
The aluminosilicate catalyst according to another aspect of the present invention
can suppress the formation of coke, resulting in a superior catalyst for which any
deterioration in the catalytic activity is suppressed.
-,
7
Moreover, in the method for producing monocyclic aromatic hydrocarbons
having a carbon number of 6 to 8 according to yet another aspect of the present
invention, by using the aluminosilicate catalyst described above, coke formation can be
suppressed, and the monocyclic aromatic hydrocarbons having a carbon number of 6 to 8
can be produced with good efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016]
FIG. I is a diagram illustrating one example of a production apparatus used for
implementing a method for producing monocyclic aromatic hydrocarbons having a
carbon number of 6 to 8 according to an embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0017]
The present invention is described below in further detail.
First is a description of a method for producing an aluminosilicate catalyst
according to an embodiment of the present invention.
The aluminosilicate catalyst according to this embodiment is a catalyst formed by
mixing and firing a crystalline aluminosilicate (a zeolite) and a binder, and can be used in
a variety of reactions which mainly utilize the acid sites of the crystalline aluminosilicate.
[0018]
[Crystalline Aluminosilicate]
Materials containing a medium pore zeolite and/or a large pore zeolite as the
main component are preferred as the crystalline aluminosilicate, as such materials exhibit
higher activity in reactions that utilize the acid sites, and for example are able to produce
8
a higher yield of monocyclic aromatic hydrocarbons in the cracking and reforming
reaction described below.
[0019]
Medium pore zeolites are zeolites having a backbone structure composed of 1 0-
membered rings, and examples of these medium pore zeolites include zeolites having
AEL, EUO, FER, HEU, MEL, MFI, NES, TON and WEI type crystal structures. Among
these, MFI type zeolites are preferred as they enable a greater increase in the yield of
monocyclic aromatic hydrocarbons.
Large pore zeolites are zeolites having a backbone structure composed of 12-
membered rings, and examples of these large pore 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 of monocyclic aromatic hydrocarbons.
[0020]
Besides the above medium pore zeolites and large pore zeolites, the crystalline
aluminosilicate may also contain small pore zeolites having a backbone structure
composed of 1 0-membered rings or smaller, and extra large pore zeolites having a
backbone structure composed of 14-membered rings or larger.
Examples of the small pore zeolites include zeolites having ANA, CHA, ERI,
GIS, KFI, LTA, NAT, PAU and YUG type crystal stmctures.
Examples of the extra large pore zeolites include zeolites having CLO and VPI
type crystal structures.
[0021]
9
Further, the crystalline aluminosilicatc may contain a pentasil zeolite as the main
component. Pentasil zeolites are typified by H-ZSM-5, and are aluminosilicates
constructed using a 5-membered ring (a pentasil backbone) as the smallest unit. In this
type ofpentasil zeolite, the molar ratio between silicon and aluminum (Si!Al ratio) can
be altered in a broad range from 6 to oo, and the solid acid content and the
hydrophilic/hydrophobic balance can be freely controlled. Further, pentasil zeolites also
have other excellent properties, including an ability to control the acid/base balance by
ion exchange.
[0022]
Further, the crystalline aluminosilicate has a molar ratio between silicon and
aluminum (Si/AI ratio) that is not more than 100, and preferably not more than 50. If the
Si/ AI ratio of the crystalline a1uminosilicate exceeds 1 00, then the yield of monocyclic
aromatic hydrocarbons tends to decrease.
Furthermore, in order to obtain a satisfactory yield of monocyclic aromatic
hydrocarbons, the Si/ AI ratio of the crystalline aluminosilicate is preferably at least 1 0.
[0023]
[First Phosphoric Acid Treatment Step]
In the present embodiment, this type of crystalline aluminosilicate is treated with
a first phosphoric acid compound to form a phosphorus-treated crystalline
aluminosilicate. In other words, by treating the ctystalline aluminosilicate with the first
phosphoric acid compound, phosphorus is supported on the crystalline aluminosilicate,
thereby forming a phosphorus-treated crystalline aluminosilicate (phosphmus-supporting
crystalline aluminosilicate). In order to prevent impediments to the subsequent mixing
and molding processes, the pmiicle size of the crystalline aluminosilicate supplied to the
above treatment is preferably adjusted to an appropriate size.
~I
I
10
The particle size of the crystalline aluminosilicate can be adjusted by sieving,
crystallization, molding, grinding, or spray drying or the like.
[0024]
Examples of the first phosphori~ acid compound include phosphoric acid (H3P04),
diammonium hydrogen phosphate ((NH4)2HP04), ammonium dihydrogen phosphate
((NH4)H2P04), and other water-soluble phosphate salts (such as sodium phosphate and
potassium phosphate), and an appropriate compound may be selected and used in
accordance with the properties and the like of the crystalline aluminosilicate that
represents the treatment target. The use of diammonium hydrogen phosphate is preferred.
Fmther, these compounds are typically used by dissolution in water or the like
and adjustment to an appropriate concenh·ation.
[0025]
Examples of the method used for treating the crystalline aluminosilicate with the
first phosphoric acid compound, namely the method used for supporting phosphorus on
the crystalline aluminosilicate, include conventional wet methods such as impregnation
methods and spraying methods.
Further, following contact treatment with this type of aqueous solution of the first
phosphoric acid compound, the phosphorus-treated crystalline aluminosilicate is obtained
by performing a drying treatment and then a firing treatment. At this time, by
evaporating substantially all oft he water content from the aqueous solution of the first
phosphoric acid compound, almost all of the phosphorus component within the first
phosphoric acid compound can be supported on the crystalline aluminosilicate.
[0026]
The drying temperature is typically at least 100°C, and preferably I l0°C or
higher. The upper limit for the drying temperature is not more than 450°C, preferably
II
not more than 400°C, and more preferably 350°C or lower. Various conventional
methods such as air firing or steam firing can be used as the firing treatment method.
The firing temperature is typically at least 500°C, and preferably 550°C or higher. The
upper limit for the firing temperature is typically not more than 1,000°C, preferably not
more than 900°C, and more preferably 800°C or lower.
The phosphorus-treated crystalline aluminosilicate that has undergone this type of
firing treatment may be used, as is, in the subsequent step, but in those cases where the
firing treatment and the like causes an increase in the particle size of the crystalline
aluminosilicate or partial powdering of the crystalline aluminosilicate, a grinding
treatment or the like is preferably performed if necessary to adjust the particle size to an
appropriate level before supplying the crystalline aluminosilicate to the subsequent step.
[0027]
The phosphoms content of the phosphorus-treated crystalline aluminosilicate,
namely the amount of supported phosphorus, reported as the mass of phosphorus atoms
relative to a value of 100 mass% for the entire mass of the phosphorus-treated crystalline
aluminosilicate, is preferably at least O.lmass% but not more than I 0.0 mass%, more
preferably at least 0.5 mass% but not more than 5.0 mass%, and stillmore preferably
about 1.0 to 3.0 mass%.
By suppmiing phosphorus on the crystalline aluminosilicate in this mmmer, the
strength (amount) of acid sites within the ctystalline aluminosilicate can be adjusted, and
hydrothermal degradation of the obtained catalyst can be suppressed.
[0028]
In those cases where the aluminosilicate catalyst is used in a process such as the
aforementioned cracking and reforming reaction for producing monocyclic aromatic
hydrocarbons, in order to suppress coke formation, particularly in fixed beds, a cycle of
12
"reaction---> regeneration---> reaction---> regeneration ... " is repeated. In this type of
reaction and regeneration cycle, coke is decomposed and removed at high temperature by
a firing treatment during regeneration, but this type of coke firing produces water. The
heat and water during firing causes hydrothermal degradation of the aluminosilicate
catalyst that can eliminate acid sites, resulting in a loss of activity and a deterioration in
the catalyst performance.
[0029]
In response to this type of phenomenon, the phosphmus supported on the
crystalline aluminosilicate weakens the acid sites of the aluminosilicate catalyst, thereby
suppressing hydrothermal degradation. Fmther, this can also inhibit the formation of
coke. However, with this type of phosphoms supporting treatment, if the amount of
supported phosphoms becomes too large, then the inherent catalytic activity provided by
the acid sites tends to decrease, and therefore as described above, the phosphoms content
is limited to not more than 10.0 mass%, and preferably not more than 5.0 mass%.
Further, in order to suppress hydrothermal degradation, the amount of phosphorus
supported is typically at least O.lmass%, and preferably 0.5 mass% or greater.
[0030]
When phosphoms is supported in this manner, the acid sites of the crystalline
aluminosilicate are adjusted, thereby suppressing the type ofhydrothennal degradation
described above.
Particularly in those cases where the obtained aluminosilicate catalyst is to be
used as a catalyst for the production of monocyclic aromatic hydrocarbons as described
below, the crystalline aluminosilicate may also include gallium and/or zinc in addition to
the suppmted phosphorus. By including gallium and/or zinc, a more efficient BTX
production can be anticipated.
-1
13
[0031]
Examples of crystalline aluminosilicates containing gallium and/or zinc include
catalysts in which gallium is incorporated within the lattice framework of the crystalline
aluminosilicate (crystalline aluminogallosilicates), catalysts in which zinc is incorporated
within the lattice framework of the crystalline aluminosilicate (crystalline
aluminozincosilicates ), catalysts in which gallium is supported on the crystalline
aluminosilicate (Ga-suppmting crystalline aluminosilicates), catalysts in which zinc is
supported on the crystalline aluminosilicate (Zn-suppmting crystalline aluminosilicates),
and catalysts including at least one of the abovefonns.
[0032]
[Mixing and Firing Step for Forming Aluminosilicate Mixture]
Subsequently, the formed phosphorus-treated crystalline aluminosilicate is mixed
with a binder, and the mixture is then dried and fired to form an aluminosilicate mixture.
[0033)
[Binder]
There are no particular limitations on the binder, and any of various binders may
be used, provided they do not impair the activity of the phosphorus-treated crystalline
aluminosilicate described above. Specific examples of materials that can be used
favorably as the binder include inorganic materials such as alumina, silica and titania,
and other materials containing these inorganic materials. Among the various
possibilities, alumina powder is preferred, as it exhibits excellent binding strength,
meaning a comparatively small amount of the binder can be used to impmt the
phosphmus-treated crystalline aluminosilicate with sufficient binding strength to enable
molding. In other words, provided the amount added of the binder can be kept to a
14
minimum, any deterioration in the activity of the aluminosilicatc catalyst due to addition
and mixing of the binder can be suppressed.
[0034]
However, alumina has more numerous acid sites, for example compared with
silica, and therefore coke formation tends to become more noticeable. On the other hand,
silica has a lower binding strength than alumina, meaning a larger amount must be added.
Further, titania has even more acid sites than alumina, and is also expensive.
[0035]
When alumina (alumina powder) is used as the binder, the blend ratio with the
aforementioned phosphorus-treated crystalline aluminosilicate is important. In other
words, as the amount of the binder is increased, better moldability is achieved and
favorable mechanical strength can be obtained for the resulting aluminosilicate catalyst.
On the other hand, as the amount of the binder is increased, the deterioration in activity
of the aluminosilicate catalyst caused by the addition of the binder becomes more
significant. The amount of the binder (alumina) contained within the aluminosilicate
catalyst is preferably at least 5 mass% but not more than 50 mass%, and is more
preferably at least 10 mass% but not more than 40 mass%.
[0036]
However, the blend ratio between the alumina (alumina powder) and the
phosphorus-treated crystalline aluminosilicate is not necessarily limited to the above
mass ratio range, and may be set to any value as appropriate.
Further, in those cases where silica is used as the binder, the amount of the binder
(silica) contained within the aluminosilicate catalyst is preferably at least I 0 mass% but
not more than 50 mass%, and is more preferably at least 15 mass% but not more than 40
mass%.
15
The binder such as the alumina (alumina powder) may be a binder that already
• contains phosphorus. However, when the binder is subjected to a phosphorus treatment
with a phosphorus compound, the binder tends to degenerate, and there is a possibility
that the performance of the binder may deteriorate. Accordingly, the type of phosphorus
treatment using a phosphorus compound described above for treatment of the crystalline
aluminosilicate is preferably not performed on the binder.
[0037]
The mixing of the phosphorus-treated crystalline aluminosilicate and the binder
may be perfonned, for example, by adding a liquid such as water or an organic solvent to
the two components and then kneading the resulting mixture.
Subsequently, the thus obtained mixture (kneaded product) is molded into the
desired shape using a molding device, and is then dried in the open atmosphere at a
temperature of at least 1 00°C, and preferably 11 ooc or higher. The molded body of the
mixture may be in any of various forms, including granules or pellets. For example,
when an extrusion molding apparatus is used as the molding device, the mixture can be
molded into.a circular cylindrical shape having any arbitrary diameter (for example, a
diameter of 0.5 to 3 mm) and height.
Subsequently, the thus obtained dried material (molded product) is fired in the
open atmosphere at a temperature of at least 500°C, and preferably 550°C or higher, thus
yielding a molded body of the aluminosilicate mixture.
[0038]
[Second Phosphoric Acid Treatment Step]
Next, the molded body of the aluminosilicate mixture is treated with a second
phosphorus compound to obtain the aluminosilicate catalyst.
-,
16
In other words, by treating the aluminosilicate mixture with the second
phosphoric acid compound, phosphorus is suppmted selectively and predominantly on
the binder. Because the aluminosilicate mixture described above has already been
molded, it may be used without further modification as the aluminosilicate mixture
supplied to this treatment, but in those cases where the firing treatment and the like has
caused an increase in the particle size of the aluminosilicate mixture or pattial powdering
of the mixture, a grinding treatment or the like is preferably performed if necessary to
adjust the particle size to an appropriate level.
[0039]
Examples of the second phosphoric acid compound include the same compounds
as the first phosphoric acid compound, such as phosphoric acid (H3P04), dianunonium
hydrogen phosphate ((NH4)2HP04), a111111onium dihydrogen phosphate ((NI-4)H2P04),
and other water-soluble phosphate salts (such as sodium phosphate and potassium
phosphate), and an appropriate compound may be selected and used in accordance with
the propetties and the like of the aluminosilicate mixture that represents the treatment
target. Further, these compounds are typically used by dissolution in water or the like
and adjustment to an appropriate concentration. Phosphoric acid can be used particularly
favorably in those cases where alumina (alumina powder) is used as the binder.
Phosphoric acid adheres selectively to the alumina binder, meaning the acid sites of the
alumiuosilicate can be left as is, while the acid sites of the binder are selectively
weakened.
[0040]
Examples of the method used for treating the molded body of the aluminosilicate
mixture with the second phosphoric acid compound, namely the method used for
17
suppmting phosphorus on the aluminosilicate mixture, include conventional wet methods
such as impregnation methods and spraying methods.
Further, following contact treatment with this type of aqueous solution of the
second phosphoric acid compound, the aluminosilicate catalyst according to the present
embodiment is obtained by performing a drying treatment and then a firing treatment. At
this time, by evaporating substantially all of the water content from the aqueous solution
of the second phosphoric acid compound, almost all of the phosphorus component within
the second phosphoric acid compound can be suppmted on the aluminosilicate mixture.
[0041]
The drying temperature is typically at least 100°C, and preferably II 0°C or
higher. The upper limit for the drying temperature is not more than 450°C, preferably
not more than 400°C, and more preferably 350°C or lower. Various conventional
methods such as air firing in the open air can be used as the firing treatment method. The
firing temperature is typically at least 500°C, and preferably 550°C or higher. The upper
limit for the firing temperature is typically not more than 1,000°C, preferably not more
than 900°C, and more preferably 800°C or lower.
Further, following this type of firing treatment, the resulting fired product is
preferably subjected to a steaming treatment (heat treatment in an atmosphere containing
water vapor).
[0042]
As is already known, by performing the above steaming treatment, AI that has
highly active acid sites can be reduced (partially eliminated) in the catalyst. In other
words, those acid sites which, although contributing to reaction, particularly in the initial
steps (initial reaction stage), tend to promote catalyst degradation as a result of coke
formation and adhesion (accumulation), can be reduced.
-,
18
[0043]
Accordingly, by using a catalyst that has been subjected to this type of treatment,
although the reaction efficiency in the initial stages deteriorates slightly, catalyst
degradation that occurs as the reaction proceeds can be suppressed. Further, because any
reduction in the yield caused by catalyst degradation can be suppressed, the yield of the
overall reaction process can be improved, despite the reduction in the amount of AI
having highly active acid sites within the catalyst.
[0044]
Fmihermore, pmiicularly in those cases where alumina is used as the binder, the
amount of acid sites within the binder can be reduced (patiially eliminated) within the
fired product, and as a result, coke formation and adhesion (accumulation) on the catalyst
can be inhibited.
[0045]
Specific examples of preferred conditions for this type of steaming treatment
include a heating temperature of at least 600°C but not more than 900°C, and a
temperature of at least 650°C but not more than 850°C is more prefened. If the
temperature is less than 600°C, then the effect of the treatment in reducing acid sites is
minimal, whereas if the temperature exceeds 900°C, then the costs required to perform
the treatment increase considerably, which is also undesirable.
[0046]
The water vapor concentration in the treatment atmosphere during the heating is
preferably at least 10% but not more than 100%, and is more preferably at least 20%. In
those cases where the water vapor concentration is less than I 00%, examples of the
coexistent gas include air or nitrogen.
19
These types of heating temperatures and water vapor concentrations may be
selected as appropriate depending on the treatment time. In other words, when the
heating temperature and water vapor concentration are high, the treatment time can be
relatively shmi, whereas when the heating temperature and water vapor concentration are
set lower, the treatment time must be lengthened relatively. The treatment time is
preferably at least 10 minutes but less than 24 hours. If the treatment time is less than 10
minutes, then achieving uniform hydrothermal treatment conditions is difficult, whereas
using a treatment time of24 hours or longer occupies the apparatus for a long period, and
is inefficient.
[0047]
Specifically, if the heating temperature is set to at least 650°C but not more than
850°C, and the water vapor concentration is set to at least 20%, then the treatment time
can be set to at least 15 minutes but not more than about 5 hours.
Examples of apparatus that can be used for performing this type of heat treatment
using water vapor include multistage kilns. In such cases, by performing the drying
treatment and the firing treatment in the earlier stages, and then performing the heat
treatment with water vapor in a later stage, the catalyst can be treated in a continuous
manner. The heat treatment using water vapor may also be performed after the catalyst is
packed into the reaction apparatus, or a batch-type heating device for performing the
hydrothermal treatment may be used.
[0048]
The aluminosilicate catalyst obtained in this matmer may be used without fmiher
modification as a fixed bed catalyst, but in those cases where the firing treatment and the
like has caused an increase in the patiicle size of the aluminosilicate catalyst or patiial
20
powdering of the catalyst, a grinding treatment or the like is preferably performed if
necessary to adjust the patticle size to an appropriate level
[0049]
The amount of additional phosphorus suppmted on the catalyst by the second
phosphoric acid treatment step, reported as the mass of phosphorus atoms relative to a
value of 100 mass% for the entire mass of the aluminosilicate catalyst obtained following
the firing treatment, is preferably at least 0.1 mass% but not more than l 0.0 mass%, more
preferably at least 0.25 mass% but not more than 3 mass%, and still more preferably
about 0.5 to 2.5 mass%. When phosphorus is supported on the aluminosilicate catalyst in
this manner, because phosphorus has been supported on the crystalline aluminosilicate by
the first phosphorus treatment step, the phosphorus from the second phosphorus
treatment step is suppmted mainly on the binder. Accordingly, because the acid sites of
the binder bind selectively to the phosphmus and are weakened, the obtained
aluminosilicate catalyst is able to suppress coke formation, for example in the production
of monocyclic aromatic hydrocarbons described below.
[0050]
Consequently, by using the method for producing an aluminosilicate catalyst
according to the present embodiment, coke formation can be suppressed in various
reactions that utilize the acid sites of the crystalline aluminosilicate, such as the
production of monocyclic aromatic hydrocarbons, and an aluminosilicate catalyst for
which deterioration in the catalytic activity can be suppressed can be produced favorably.
[0051]
Furthermore, in the mixing and firing step, because the phosphorus-treated
aluminosilicate and the binder are mixed (kneaded) and molded, and the resulting
molded body is then fired, the thus obtained aluminosilicate catalyst has good
21
mechanical strength, and can therefore be used favorably in fixed beds or the like for
performing the type of cracking and reforming reaction described below.
Further, by using a material containing a medium pore zeolite and/or a large pore
zeolite, or a pentasil zeolite or MFI zeolite, as the crystalline aluminosilicate, an
aluminosilicate catalyst of higher activity can be obtained.
[0052]
Further, if a material containing alumina is used as the binder, then because
alumina exhibits excellent binder performance, and can therefore be added in a smaller
amount, the catalytic performance of the thus obtained aluminosilicate catalyst can be
improved.
Furthermore, in those cases where a material containing alumina is used as the
binder, by using phosphoric acid as the second phosphorus compound, the phosphoric
acid can be adhered selectively to the alumina binder, meaning the acid sites of the
aluminosilicate can be left as is, while the acid sites of the binder are selectively
weakened. Accordingly, coke formation and accumulation in the obtained
aluminosilicate catalyst can be suppressed.
[0053]
Fmiher, an aluminosilicate catalyst according to an embodiment of the present
invention, obtained by using this type of method for producing an aluminosilicate
catalyst, can suppress coke formation in various reactions that utilize the acid sites of the
crystalline aluminosilicate.
[0054]
[Method for Producing Monocyclic Aromatic Hydrocarbons having a Carbon Number of
6 to 8]
22
Next is a description of a method for producing monocyclic aromatic
hydrocarbons having a carbon number of 6 to 8, which uses an aluminosilicate catalyst
according to an embodiment of the present invention, obtained using the aforementioned
method for producing an aluminosilicate catalyst, as the monocyclic aromatic
hydrocarbon production catalyst. FIG. 1 is a diagram illustrating one example of a
production apparatus used for implementing the method for producing monocyclic
aromatic hydrocarbons having a carbon number of 6 to 8 according to an embodiment of
the present invention. The production apparatus 1 illustrated in FIG. 1 is used for
producing monocyclic aromatic hydrocarbons having a carbon number of 6 to 8 (a BTX
fraction) li"om a feedstock oil.
[0055]
(Feedstock Oil)
The feedstock oil used in the present embodiment is an oil having a I 0 vol%
distillation temperature of at least 140°C and a 90 vol% distillation temperature of not
more than 390°C. With oils having a I 0 vol% distillation temperature ofless than
140°C, the targeted monocyclic aromatic hydrocarbons tend to decompose, resulting in a
decrease in productivity. Further, when an oil having a 90 vol% distillation temperature
exceeding 3 90°C is used, then not only does the yield of the monocyclic aromatic
hydrocarbons decrease, but the amount of coke accumulation on the monocyclic aromatic
hydrocarbon production catalyst tends to increase, which may cause a rapid deterioration
in the catalytic activity. The I 0 vol% distillation temperature ofthe feedstock oil is
preferably 150°C or higher, and the 90 vol% distillation temperature of the feedstock oil
is preferably not more than 360°C. In this description, the 10 vol% distillation
temperature and the 90 vol% distillation temperature refer to values measured in
23
accordance with JIS K 2254 "Petroleum Products - Determination of Distillation
Characteristics".
[0056]
Examples of feedstock oils having a I 0 volume %distillation temperature of at
least 140°C and a 90 volume% distillation temperature of not more than 390°C include
light cycle oils (LCO) produced in fluid catalytic crackers, hydrotreated LCO, coal
liquefaction oil, hydrocracked oil ft:om heavy oils, straight-nm kerosene, straight-run gas
oil, coker kerosene, coker gas oil, hydrocracked oil from oil sands, thermally cracked
heavy oil obtained ft·om ethylene production apparatus, hydrogenated products of
thermally cracked heavy oil obtained from ethylene production apparatus, heavy catalytic
cracking gasoline (HCCG) obtained from fluid catalytic crackers, and heavy oils (PLATBTM)
obtained from catalytic reformers.
[0057]
A light cycle oil (LCO) produced in a fluid catalytic cracker or the like contains
large amounts of aromatic hydrocarbons. A thermally cracked heavy oil obtained from
an ethylene production apparatus is a heavier fraction than the BTX fraction obtained
from the ethylene production apparatus, and contains a large amount of aromatic
hydrocarbons. When a fraction is used in which the aromatic hydrocarbons include a
large amount of polycyclic aromatics, because these polycyclic aromatics can cause coke
formation in the subsequent cracking and reforming reaction, the fi·action is preferably
subjected to hydro treating. However, if a fraction derived from an aforementioned
thermally cracked heavy oil or LCO contains a large amount of monocyclic aromatic
hydrocarbons, then hydrotreating may not necessarily be needed.
Similarly for other feedstock oils, the feedstock oil is preferably selected using
the same basic reasoning outlined above, and feedstock oils which are likely to produce
24
an excessive amount of coke in the cracking and reforming reaction are preferably
avoided. Heavy catalytic cracking gasoline obtained from fluid catalytic crackers and
heavy oils obtained from catalytic reformers are fractions which contain minimal
amounts of polycyclic aromatics in the feedstock oil, and therefore hydrotreating need
not be performed.
[0058]
Polycyclic aromatic hydrocarbons exhibit low reactivity and are difficult to
convert to monocyclic aromatic hydrocarbons in the cracking and reforming reaction of
the present embodiment. However, on the other hand, ifthese polycyclic aromatic
hydrocarbons are hydrogenated in a hydrogenation reaction and converted to
naphthenobenzenes, and these naphthenobenzenes are then supplied to the cracking and
reforming reaction, they can be converted to monocyclic aromatic hydrocarbons.
However, among polycyclic aromatic hydrocarbons, tricyclic and higher aromatic
hydrocarbons consume a large amount of hydrogen in the hydrogenation reaction step,
and suffer from poor reactivity in the cracking and reforming reaction step even
following conversion to hydrogenation reaction products, and therefore the feedstock oil
preferably does not contain a large amount of such tricyclic and higher aromatic
hydrocarbons. Accordingly, the amount oftricyclic and higher aromatic hydrocarbons
within the feedstock oil is preferably not more than 25 vol%, and more preferably 15
vol% or less.
[0059]
In this description, the polycyclic aromatic fraction describes the combined total
of the amount ofbicyclic aromatic hydrocarbons (the bicyclic aromatic fraction) and the
amount of tricyclic and higher aromatic hydrocarbons (the tricyclic and higher aromatic
fi'action), which is either measured in accordance with JPI-5S-49 "Petroleum Products -
25
Determination of Hydrocarbon Types - High Performance Liquid Chromatography", or
determined by analysis using FID gas chromatography or two-dimensional gas
chromatography. In the following description, an amount of polycyclic aromatic
hydrocarbons, bicyclic aromatic hydrocarbons or tricyclic or higher aromatic
hydrocarbons reported using the units vol% represents an amount that has been measured
in accordance with JPI-58-49, whereas an amount that is reported using the units mass%
represents an amount that has been measured on the basis ofFID gas clu·omatography or
two-dimensional gas chromatography.
[0060]
(Hydrotreatment of Feedstock Oil)
In those cases where the feedstock oil is subjected to a preliminary
hydrotreatment, the hydrogenation reaction is preferably performed in accordance with
the following guidelines. In the hydrogenation reaction, the hydrogenation feedstock oil
is not subjected to complete hydrogenation, but rather a partial hydrogenation. In other
words, in the main, the bicyclic aromatic hydrocarbons within the feedstock oil are
hydrogenated selectively, and convel1ed to monocyclic aromatic hydrocarbons in which
only one of the aromatic rings has been hydrogenated (such as naphthenobenzenes).
Examples of these monocyclic aromatic hydrocarbons include indane, tetralin and
alkyl benzenes.
[0061]
If a patiial hydrotreatment is performed in tltis manner, then the amount of
hydrogen consumed in the hydrogenation reaction process can be suppressed, and the
amount of heat generated during the treatment can also be suppressed. For example,
when naphthalene, which is a representative bicyclic aromatic hydrocarbon, is
hydrogenated to form decalin, the amount of hydrogen consumed is 5 mol per I mol of
=--=t /
I
26
naphthalene, whereas hydrogenation to form tetralin can be achieved with 2 mol of
hydrogen consumption. Further, the feedstock oil (thermally cracked heavy oil) includes
a large fraction containing indenes, and the amount of hydrogen consumption required to
hydrogenate this fraction to indanes is even less than the amount of hydrogen required to
hydrogenate naphthalene to decalin. Accordingly, the bicyclic aromatic hydrocarbons in
the feedstock oil can be conve1ied more efficiently to naphthenobenzenes.
The hydrogen used in the hydrogenation reaction may utilize the hydrogen
produced in the cracking and reforming reaction described below.
[0062]
A conventional hydrogenation reactor can be used as the hydrogenation reaction
device 2 for performing this type of hydrotreatment. In this hydrogenation reaction, the
hydrogen pmiial pressure at the reactor inlet is preferably from I to 9 MPa. The lower
limit is preferably at least 1.2 MPa, and more preferably 1.5 MPa or higher. Further, the
upper limit is preferably not more than 7 MPa, and more preferably 5 MPa or lower. If
the hydrogen partial pressure is less than 1 MPa, then coke formation on the catalyst
becomes more severe, shortening the lifespan of the catalyst. In contrast, ifthe hydrogen
partial pressure exceeds 9 MPa, then complete hydrogenation, such as the case where
both rings of a bicyclic aromatic hydrocarbon are hydrogenated, tends to increase, which
causes a dramatic increase in the amount of hydrogen consumed, reduces the yield of
monocyclic aromatic hydrocarbons, and increases the construction costs for the
hydrogenation reactor and peripheral equipment, making economic viability a concern.
[0063]
Further, the liquid hourly space velocity (LHSV) for the hydrogenation reaction
in the hydrogenation reaction device 2 is preferably within a range from 0.05 to 10 h- 1
•
The lower limit is preferably at least 0.1 h- 1
, and more preferably 0.2 h-1 or higher.
cc~,/
~
27
Further, the upper limit is preferably not more than 5 h- 1
, and more preferably 3 h-1 or
lower. If the LHSV is less than 0.05 h-1
, the construction costs for the reactor become
excessive, and economic viability becomes a concern. In contrast, if the LHSV exceeds
10 h-1
, then the hydt:otreatment of the feedstock oil may not proceed sufficiently,
meaning the targeted hydrogenation products may be unobtainable.
[0064]
The reaction temperature of the hydrogenation reaction performed in the
hydrogenation reaction device 2 (the hydrogenation temperature) is preferably fi-om
150°C to 400°C. The lower limit is more preferably at least I 70°C, and stillmore
preferably 190°C or higher. Further, the upper limit is more preferably not more than
380°C, and still more preferably 370°C or lower. If the reaction temperature falls below
I 50°C, then satisfactory hydro treatment of the feedstock oil tends to be unachievable.
On the other hand, if the reaction temperature exceeds 400°C, then the gas fraction byproduct
tends to increase, meaning the yield of the hydro treated oil decreases, which is .
also undesirable.
[0065]
The hydrogen/oil ratio during the hydrogenation reaction in the hydrogenation
reaction device 2 is preferably from I 00 to 2,000 NLIL. The lower limit is more
preferably at least I 10 NLIL, and still more preferably I20 NLIL or higher. Fmther, the
upper limit is more preferably not more than I ,800 NLIL, and stillmore preferably I ,500
NLIL or lower. If the hydrogen/oil ratio is less than IOO NLIL, then coke formation
tends to occur on the catalyst at the reactor outlet, thus shortening the catalyst lifespan.
In contrast, if the hydrogen/oil ratio exceeds 2,000 NLIL, then the construction costs for
the recycle compressor become excessive, making economic viability a concern.
[0066]
28
There are no pmiicular limitations on the reaction system used for the
hydrotrealment in the hydrogenation reaction device 2, and the system can usually be
selected from among various processes such as fixed bed and moving bed systems.
Among these, fixed bed systems are preferred for reasons including inexpensive
construction costs and operating costs. Further, the hydrogenation reaction device 2 is
preferably a tower-like device.
[0067]
There are no pmiicular limitations on the hydrotreating catalyst used in the
hydrotreatment, provided the catalyst is capable of selectively hydrogenating the bicyclic
aromatic hydrocarbons in the feedstock oil to achieve conversion to monocyclic aromatic
hydrocarbons in which only one of the aromatic rings has been hydrogenated (namely,
naphthenobenzenes ). Examples of preferred hydrotreating catalysts include those
containing at least one metal selected fi·om among metals belonging to group 6 of the
periodic table of elements, and at least one metal selected from among metals belonging
to groups 8 to 10 of the periodic table of elements. The metal belonging to group 6 of the
periodic table of elements is preferably molybdenum, tungsten or chromium, and is more
preferably molybdenum or tungsten. The metal belonging to groups 8 to I 0 of the
periodic table of elements is preferably iron, cobalt or nickel, and is more preferably
cobalt or nickel. These metals may be used individually, or combinations of two or more
metals may be used. Specific examples of metal combinations that can be used favorably
include molybdenum-cobalt, molybdenum-nickel, tungsten-nickel, molybdenum-cobaltnickel,
and tungsten-cobalt-nickel. The periodic table of elements mentioned here refers
to the long period-type periodic table of elements prescribed by the International Union
of Pure and Applied Chemistry (IUPAC).
[0068]
29
The hydrotreating catalyst is preferably a catalyst in which the metal described
above is supported on an inorganic carrier containing aluminum oxide. Preferred
examples of the inorganic carrier containing aluminum oxide include alumina, aluminasilica,
alumina-boria, alumina-titania, alumina-zirconia, alumina-magnesia, aluminasilica-
zirconia, alumina-silica-titania, and carriers prepared by adding alumina to a
porous inorganic compound including the various zeolites and any of the various clay
minerals such as sepiolite and montmorillonite. Among these various possibilities,
alumina is particularly preferred.
[0069]
The hydrotreating catalyst is preferably obtained by supp01iing, on an inorganic
carrier containing aluminum oxide, I 0 to 30 mass% of at least one metal selected from
among metals belonging to group 6 of the periodic table of elements, and I to 7 mass%
of at least one metal selected li"om among metals belonging to groups 8 to I 0 of the
periodic table of elements, relative to the total catalyst mass composed of the combined
mass of the inorganic carrier and the metals. If either the mass of the metal belonging to
group 6 of the periodic table of elements or the mass of the metal belonging to groups 8
to 10 of the periodic table of elements is less than the respective lower limit mentioned
above, then the catalyst tends to lack adequate hydrotreating activity, whereas if either
amount exceeds the respective upper limit, then not only does the cost of the catalyst
increase, but aggregation or the like of the supported metals becomes more likely,
meaning the catalyst tends not to exhibit adequate hydrotreating activity.
[0070]
Although there are no particular limitations on the metal precursors that are used
in supporting the aforementioned metals on the inorganic carrier, inorganic salts or
organometallic compounds of the metals are typically used, and water-soluble inorganic
30
salts can be used particularly favorably. In the supporting step, a solution, and preferably
an aqueous solution, of the metal precursors is used to support the metals. The
suppotting operation preferably utilizes a conventional method such as a dipping method,
impregnation method or coprecipitation method.
[0071]
The carrier with the metal precursors supported thereon is dried, and is then
preferably fired in the presence of oxygen to initially convC!t the metals to oxides. Then,
prior to hydrotreating the feedstock oil, a sulfidization treatment known as presulfiding is
preferably performed to convert the metals to sulfides.
Although there are no particular limitations on the conditions for the presulfiding
treatment, it is preferable that a sulfur compound is added to the petroleum fraction or
thermally cracked heavy oil (hereafter referred to as the presulfiding feedstock oil), and
the resulting mixture is then brought into continuous contact with the hydrotreating
catalyst under conditions including a temperature of200 to 380°C, an LHSV value of 1
to 2 h-1
, a pressure equal to that used during the hydrotreatment operation, and a
treatment time of at least 48 hours. Although there are no particular limitations on the
sulfur compound added to the presulfiding feedstock oil, dimethyl disulfide (DMDS),
sulfazole, or hydrogen sulfide or the like is preferred, and these compounds are
preferably added to the presulfiding feedstock oil in an amount of about I mass% relative
to the mass of the presulfiding feedstock oil.
[0072]
As illustrated in FIG. 1, the hydrotreated oil (partial hydrogenation product)
obtained from the hydrogenation reaction device 2 (hydrogenation reaction) is fed into a
subsequent dehydrogenation tower 3 in which hydrogen is removed from the oil, and is
then supplied to a cracking and reforming reaction device 4 to undergo the cracking and
31
reforming reaction. Further, a fraction containing mainly hydrocarbons with a carbon
number of about 9 to I 0 and containing minimal polycyclic aromatics and therefore not
requiring hydrogenation may be supplied directly to the cracking and reforming reaction
device 4 together with the hydrotreated oil.
[0073]
[Cracking and Reforming Reaction]
The cracking and reforming reaction device 4 contains a monocyclic aromatic
hydrocarbon production catalyst, and the supplied feedstock oil (hydrogenated oil)
contacts this catalyst and undergoes reaction, yielding a product containing monocyclic
aromatic hydrocarbons having a carbon number of 6 to 8.
(Monocyclic Aromatic Hydrocarbon Production Catalyst)
In the present embodiment, the aluminosilicate catalyst described above, namely
the aluminosilicate catalyst obtained using the method for producing an aluminosilicate
catalyst according to an embodiment of the present invention, is used as the monocyclic
aromatic hydrocarbon production catalyst.
[0074]
(Reaction System)
In the present embodiment, a fixed bed system is used as the reaction system for
the cracking and reforming reaction device 4, namely the reaction system used for
bringing the feedstock oil (hydrogenated oil) into contact with the monocyclic aromatic
hydrocarbon production catalyst within the cracking and reforming reaction device 4, and
inducing the cracking and reforming reaction.
Compared with fluidized beds and moving beds, the equipment costs for fixed
bed systems are significantly cheaper. In other words, the construction costs and
operating costs for fixed beds are significantly cheaper than those for fluidized beds or
32
moving beds. In the present embodiment, as illustrated in FIG. 1, a fixed bed cracking
and reforming reaction device 4 (fixed bed reactor 4) is used, and two of these fixed bed
reactors 4 are used. Although reaction and regeneration can be repeated using a single
fixed bed reactor, in order to enable the reaction to be performed continuously, it is
preferable to install two or more reactors, and alternately repeat reaction and regeneration
for these reactors.
[0075]
Two fixed bed reactors 4 are illustrated in FIG. I, but the invention is not limited
to this configuration, and three or more reactors may also be installed. In other words, in
a fixed bed cracking and reforming reaction device, as the cracking and reforming
reaction proceeds, coke adheres in particular to the catalyst surface, and the activity of
the catalyst deteriorates. When the activity deteriorates in this manner, the yield of the
monocyclic aromatic hydrocarbons having a carbon number of 6 to 8 (the BTX fraction)
decreases. As a result, the catalyst must be subjected to a regeneration treatment.
[0076]
Accordingly, in the fixed bed cracking and reforming reaction device 4 (fixed bed
reactor), once the device has been operated for a prescribed period that has been set in
advance, the catalyst for which the activity has deteriorated as a result of coke adhesion
is subjected to a regeneration treatment. In other words, two or more cracking and
reforming reaction devices 4 (fixed bed reactors) are used, and the cracking and
reforming reaction, and the regeneration of the monocyclic aromatic hydrocarbon
production catalyst are repeated, while the reaction devices are exchanged on a regular
basis.
The operation time for which a single cracking and reforming reaction device 4
can be operated continuously differs depending on the size of the device and the various
33
operating conditions (reaction conditions), but is typically from several hours to about I 0
days. If the number of reactors within the cracking and reforming reaction device 4 (the
number of fixed bed reactors) is increased, then the continuous operating time for each
reactor can be shmiened, and the degree of deterioration in the catalytic activity can be
suppressed, meaning the time required for regeneration can also be shortened.
[0077]
In the present embodiment, the aluminosilicate catalyst described above is used as
the monocyclic aromatic hydrocarbon production catalyst, and this aluminosilicate
catalyst suppresses coke formation, thus suppressing any deterioration in the catalytic
activity. Accordingly, compared with the case where a conventional monocyclic
aromatic hydrocarbon production catalyst is used, the present embodiment is able to
suppress any decrease in the BTX production efficiency (conversion efficiency) caused
by coke formation during continuous operation of a single cracking and refmming
reaction device 4. In other words, when the continuous operating time in a single
cracking and reforming reaction device 4 is set to the same level as a conventional
device, the BTX production efficiency can be improved compared with the conventional
device. Further, if the BTX production efficiency in a single continuous operation were
to be set to the same level as a conventional device, then the single continuous operation
can be lengthened compared with the conventional device. Accordingly, by lengthening
the "reaction-> regeneration" cycle, the costs and the like required for the regeneration
of the monocyclic aromatic hydrocarbon production catalyst can be reduced, thereby
significantly reducing the operating costs compared with conventional devices.
[0078]
(Reaction Temperature)
34
Although there are no pmiicular limitations on the reaction temperature during
contact and reaction of the feedstock oil with the catalyst, the temperature is preferably
from 350°C to 700°C, and more preferably from400°C to 650°C. If the reaction
temperature is less than350°C, the reaction activity is unsatisfactory. If the reaction
temperature exceeds 700°C, then the reaction becomes unfavorable from an energy
perspective, and coke formation increases dramatically, resulting in a decrease in the
production efficiency for the target product.
[0079]
(Reaction Pressure)
The reaction pressure during contact and reaction of the feedstock oil with the
catalyst is typically from 0.1 MPaG to 2.0 MPaG. In other words, contact between the
feedstock oil and the monocyclic aromatic hydrocarbon production catalyst is performed
at a pressure of 0.1 MPaG to 2.0 MPaG.
In the present embodiment, because the reaction concept is completely different
from a conventional hydrocracking method, the types of high-pressure conditions
deemed advantageous in hydro cracking are completely unnecessary. In contrast, a
higher pressure than necessary accelerates the cracking process, resulting in the
production of untargeted light gas by~ products, and is therefore undesirable. Fmiher, the
fact that high-pressure conditions are not required is also advantageous in terms of design
of the reaction device. In other words, provided the reaction pressure is from 0.1 MPaG
to 2.0 MPaG, the hydrogen transfer reaction can be performed efficiently.
[0080]
(Contact Time)
There are no particular limitations on the contact time between the feedstock oil
and the catalyst, provided the actual reaction proceeds as desired, but the gas transit time
35
across the catalyst is preferably from 2 to 150 seconds, more preferably from 3 to 100
seconds, and still more preferably from 5 to 80 seconds. If the contact time is less than 2
seconds, then a chi eying any substantial reaction is difficult. If the contact time exceeds
150 seconds, then deposition of carbon matter on the catalyst due to coking or the like
tends to increase, or the amount of light gas generated by cracking increases, and the
device also tends to increase in size, all of which are undesirable.
[0081]
(Regeneration Treatment)
Once the cracking and reforming reaction has been performed for a prescribed
time in the cracking and reforming reaction device 4, the operation of the cracking and
reforming reaction is switched to a separate cracking and reforming reaction device 4,
and in the cracking and reforming reaction device 4 in which operation of the cracking
and reforming reaction has been halted, the monocyclic aromatic hydrocarbon production
catalyst for which the activity has deteriorated is subjected to regeneration.
[0082]
The deterioration in catalytic activity is mainly due to coke adhesion to the
catalyst surface, and therefore a treatment for removing the coke from the catalyst
surface is performed as a regeneration treatment. Specifically, air is passed through the
cracking and reforming reaction device 4, and the coke adhered to the catalyst surface is
combusted. Because the cracking and reforming reaction device 4 is maintained at a
satisfactorily high temperature, simply passing air through the device is sufficient to
easily combust the coke adhered to the catalyst surface. However, if normal air is
supplied to and passed tlu·ough the cracking and reforming reaction device 4, then there
is a possibility that sudden combustion may occur. Accordingly, air that has been
premixed with nitrogen to lower the oxygen concentration is preferably supplied to and
36
passed through the cracking and reforming reaction device 4. In other words, the air
used in the regeneration treatment has preferably had the oxygen concentration reduced
to a value from several % to about I 0%. Further, there is no necessity that the reaction
temperature and the regeneration temperature be the same, and a suitable temperature
may be set as appropriate.
[0083]
(Refining and Collection ofBTX Fraction)
The cracking and reforming reaction product discharged from the cracking and
reforming reaction device 4 includes a gas containing olefins having a carbon number of
2 to 4, a BTX fi·action containing benzene, toluene and xylene, and aromatic
hydrocarbons of C9 or higher. Accordingly, a refining and collection device 5 provided
downstream from the cracking and reforming reaction device 4 separates the cracking
and reforming reaction product into each of these components, and refmes and collects
each component.
[0084]
The refining and collection device 5 has a BTX fraction collection tower 6 and a
gas separation tower 7.
The BTX fraction collection tower 6 distills the aforementioned cracking and
reforming reaction product, and separates the product into a light fraction having a
carbon number of 8 or less, and a heavy fraction having a carbon number of 9 or higher.
The gas separation tower 7 distills the light fi·action having a carbon number of 8 or less
separated in the BTX fraction collection tower 6, and separates the fraction into a BTX
fraction containing benzene, toluene and xylene, and a gas fraction containing
compounds having lower boiling points. This enables the BTX fraction composed of
37
monocyclic aromatic hydrocarbons with a carbon number of 6 to 8 to be produced with
excellent efficiency.
[0085]
(Recycling Treatment)
Further, the heavy fraction having a carbon number of 9 or higher (the bottom
fraction) separated in the BTX fraction collection tower 6 is returned to the
hydrogenation reaction device 2 via a recycling line 8, and is supplied a second time to
the hydrogenation reaction step together with the kerosene and light oil fraction that
functions as the feedstock oil. In other words, this heavy fraction (bottom fraction)
passes through the hydrogenation reaction device 2 and is returned to the cracking and
reforming reaction device 4, where it is re-supplied to the cracking and reforming
reaction.
[0086]
In the method for producing monocyclic aromatic hydrocarbons having a carbon
number of 6 to 8 according to the present embodiment, the aluminosilicate catalyst
described above is used as the monocyclic aromatic hydrocarbon production catalyst, and
because this aluminosilicate catalyst suppresses coke fmmation and is resistant to any
deterioration in activity, the BTX production efficiency can be improved compared with
the case where a conventional monocyclic aromatic hydrocarbon production catalyst is
used. Alternatively, the "reaction ---+regeneration" cycle may be lengthened, enabling a
significant reduction in operating costs compared with conventional devices.
[0087]
Furthermore, because two or more fixed bed reactors are used for the cracking
and reforming reaction device 4, and these reactors are exchanged periodically while the
cracking and reforming reaction and the regeneration of the monocyclic aromatic
38
hydrocarbon production catalyst are repeated, the BTX fraction can be produced with
excellent production efficiency. Fmiher, because fixed bed reactors are used, for which
the equipment costs are significantly cheaper than fluidized bed reactors, the costs of
constructing the devices used in the cracking and reforming processes can be kept
satisfactorily low.
[0088]
The present invention is not limited to the embodiments described above, and
various modifications are possible without depm1ing from the scope of the present
invention.
For example, the above embodiments described the case in which an
aluminosilicate catalyst obtained using the method for producing an aluminosilicate
catalyst according to one aspect of the present invention was used as a monocyclic
aromatic hydrocarbon production catalyst in a cracking and reforming reaction in a BTX
production process, but as mentioned above, the aluminosilicate catalyst according to the
present invention can also be used in a variety of other reactions that utilize the acid sites
of the crystalline aluminosilicate besides this cracking and reforming reaction.
[0089]
Specifically, the aluminosilicate catalyst can also be used in ethylene-propylene
synthesis fi·ommethanol, propylene synthesis from methanol and butene, propylene
synthesis fi·om dimethyl ether, propylene synthesis via catalytic cracking of C4 to C8
paraffin, propylene synthesis via catalytic cracking of C4 to C8 olefins, gasoline
synthesis fi·om methanol, ethylene synthesis by dehydrogenation of ethane, propylene
synthesis by dehydrogenation of propane, butene synthesis by dehydrogenation of
butane, styrene synthesis by dehydrogenation of ethylbenzene, BTX synthesis by
cyclodehydrogenation of C2 to C7 paraffin, BTX synthesis by cyclodehydrogenation of
39
C4 to C5 olefins, xylene synthesis by methylation of toluene, catalytic dewaxing
processes for producing lubricant base oils, para-xylene synthesis by isomerization of
mixed xylene, para-xylene synthesis from benzene-toluene-C9 aroma by transalkylation
or disproportionation, alkylation of benzene (synthesis of ethyl benzene from benzene and
ethylene, synthesis of cumene from benzene and propylene), synthesis of pyridines,
synthesis of cyclohexanol, dimerization of propylene or butenes, and alkylation of
olefins, and in any of these cases, coke formation can be suppressed.
EXAMPLES
[0090]
The present invention is described below in further detail using a series of
examples and comparative examples, but the present invention is in no way limited by
these examples.
[0091]
[Method for Producing Hydrotreated Oil of Feedstock Oil]
(Preparation of Hydrotreating Catalyst)
Water glass No.3 was added to I kg of an aqueous solution of sodium aluminate
with a concentration of 5 mass%, and the resulting mixture was placed in a container
held at 70°C. Fmiher, a solution obtained by adding an aqueous solution of titanium (IV)
sulfate (Ti02 content: 24 mass%) to I kg of an aqueous solution of aluminum sulfate
with a concentration of2.5 mass% was prepared in another container held at 70°C, and
this solution was then added dropwise over 15 minutes to the above aqueous solution
containing sodium aluminate. The amounts of the above water glass and the titanium
sulfate aqueous solution were adjusted to provide the prescribed amounts of silica and
titania respectively.
40
[0092]
The point where the pH of the mixed solution reached 6.9 to 7.5 was deemed the
end point, and the thus obtained slurry-like product was then filtered through a filter to
obtain a cake-like slurry. This cake-like slurry was transferred to a container fitted with a
reflux condenser, 300 ml of distilled water and 3 g of a 27% aqueous solution of
ammonia were added, and the mixture was stirred under heat at 70°C for 24 hours. The
stirred slurry was placed in a kneading device, and kneading was performed while
heating to at least 80°C to remove moisture, thus obtaining a clay-like kneaded product.
[0093]
The thus obtained kneaded product was extmded into a cylindrical shape having a
diameter of 1.5 mm using an extmsionmolding apparatus, and following d1ying at II 0°C
for one hour, was fired at 550°C to obtain a molded can-ier. Subsequently, a 300 g
sample of the obtained molded carrier was impregnated by spraying with an
impregnation solution prepared by adding molybdenum trioxide, cobalt (II) nitrate
hexahydrate and phosphoric acid (concentration: 85%) to !50 ml of distilled water and
then adding sufficient malic acid to achieve dissolution.
The amounts used of the molybdenum trioxide, the cobalt (II) nitrate hexahydrate
and the phosphoric acid were adjusted to achieve the prescribed amounts of supported
material. The sample impregnated with the impregnation solution was dried at II 0°C for
one hour, and was then fired at 550°C to obtain a catalyst A. Based on the mass of the
carrier, the catalyst A had an Si02 content of 1.9 mass% and a Ti02 content of2.0
mass%, whereas based on the mass of the catalyst, the amount of supported Mo03 was
22.9 mass%, the amount of supported CoO was 2.5 mass%, and the amount of supported
P20s was 4.0 mass%.
[0094]
-,
--41
(Preparation of Feedstock Oils)
A light cycle oil A obtained from an FCC apparatus was prepared. Further, a
distillation operation was used to separate only the light fraction from a thermally
cracked heavy oil obtained from an ethylene production apparatus, thus preparing a
thermally cracked heavy oil, and this thermally cracked heavy oil was mixed with
components (aromatic hydrocarbons) having a carbon number of9 or higher separated
and collected in a cracked gasoline collection unit, thus preparing a thermally cracked
heavy oil B. A heavy catalytic racking gasoline C obtained from an FCC apparatus, and
a heavy oil D obtained fi·om a catalytic reformer were also prepared. The propetiies of
each of these feedstock oils are shown in Table I.
[0095]
[Table 1]
Property
Light cycle oil Thennally crocked Heavy catalytic Catalytic reformer
A heavy oil B crocking gasoline C heavy oil D
Density, l5°C 0.9328 0.912 0.835 0.885
Kinematic viscosity, 30°C 3.007 1.074 --- 0.9180
Kinematic viscosity, 40°C --- 0.9457 --- 0.8118
Sulfur fraction 0.1600% 0.001% 0.002% 0.0003%
Distillation properties, oc
IBP 182 163 153 164
TIO 213 171 165 166
T90 343 221 202 184
EP 373 252 213 264
Saturated fraction, % 21 4 29 I
Aromatic fraction, % 76 95 64 64
Bicyclic or higher
46 23 3 6
aromatic fraction, %
[0096]
(Hydrotreating Reaction of Feedstock Oils)
42
A fixed bed continuous flow reaction apparatus was packed with the above
catalyst A, and presulfiding of the catalyst was first performed. In other words, to a
fraction equivalent to a straight-run gas oil (the presulfiding feedstock oil) having a
density at l5°C of 851.6 kg/m3
, an initial boiling point of231 oc and an end point of
376°C in a distillation test, a sulfhr content repmted as a mass of sulfur atoms relative to
the mass of the presulfiding feedstock oil of 1.18 mass%, and a color L of 1.5, was added
!mass% ofDMDS relative to the mass of the fraction, and the resulting mixture was
supplied continuously to the catalyst A for 48 hours.
Subsequently, using the light cycle oil A and the thermally cracked heavy oil B
shown in Table I as separate feedstock oils, hydrotreating was performed at a reaction
temperature of 300°C, LHSV = 1.0 h'1
, a hydrogen/oil ratio of 500 NLIL, and a pressure
of3 MPa. The propetties of the thus obtained hydrogenated light cycle oil A-I and the
hydrogenated thermally cracked heavy oil B-I are shown in Table 2.
[0097]
[Table 2]
Property
Hydrogenated light cycle Hydrogenated thermally
oil A-1 cracked heavy oil B-1
Density, l5°C 0.9051 0.902
Kinematic viscosity, 30°C 2.938 ---
Kinematic viscosity, 40°C --- 0.9478
Sulfur fraction 0.0003% 0.0002%
Distillation properties, oc
IBP 189 160
TIO 212 169
T90 330 219
EP 368 251
Saturated fraction, % 34 7
Aromatic fraction, % 66 93
Bicyclic or higher 10 4
43
aromatic fiaction, %
[0098]
The distillation propetiies shown in Tables 1 and 2 were measured in accordance
with JIS K 2254 "Petroleum Products - Determination of Distillation Characteristics".
Further, the density values (at 15°C) shown in Table 1 were measured in accordance with
JIS K 2254 "Petroleum Products- Determination of Distillation Characteristics", the
kinematic viscosity values (at 30°C or 40°C) were measured in accordance with JIS K
2283 "Crude Oil and Petroleum Products- Determination of Kinematic Viscosity and
Calculation of Viscosity Index from Kinematic Viscosity", and the sulfur fraction was
measured in accordance with JIS K 2541 "Crude oil and Petroleum Products -
Determination of Sulfur Content".
Fmihermore, for each of the compositions in Tables 1 and 2, the saturated
hydrocarbon fraction and the aromatic hydrocarbon fraction obtained by silica gel
chromatographic separation were each subjected to mass analysis using the EI ionization
method (apparatus: JMS-700, manufactured by JEOL Ltd.), and a type analysis of the
hydrocarbons was performed in accordance with ASTM D2425 "Standard Test Method
for Hydrocarbon Types in Middle Distillates by Mass Spectrometry".
[0099]
[Method for Producing Aromatic Hydrocarbons]
(Monocyclic Aromatic Hydrocarbon Production Catalyst Preparation Example)
-Preparation of Phosphorus-Treated Crystalline Aluminosilicate (MFI Zeolite)
A solution (A) composed of 1705.2 g of sodium silicate (J sodium silicate No. 3,
Si02 : 28 to 30 mass%, Na: 9 to 10 mass%, remainder: water, manufactured by Nippon
Chemical Industrial Co., Ltd.) and 2,227.6 g of water, and a solution (B) composed of
44
64.3 g of Ah(S04)J·14-18H20 (special reagent grade, manufactured by Wako Pure
Chemical Industries, Ltd.), 369.2 g oftetrapropylanunonium bromide, 152.1 g of H2S04
(97 mass%), 326.7 g ofNaCl and 2,975.7 g of water were prepared separately.
[0100]
· Subsequently, with the solution (A) undergoing constant stirring at room
temperature, the solntion (B) was added gradually to the solution (A). The resulting
mixture was stirred vigorously for 15 minutes using a mixer, thereby breaking up the gel
and forming a uniform fine milky mixture.
This mixture was then placed in a stainless steel autoclave, and a crystallization
operation was performed under self-generated pressure, under conditions including a
temperature of 165°C, a time period of 72 hours, and a stirring speed of 1 00 rpm.
Foil owing completion of the crystallization operation, the product was filtered, the solid
product was collected, and an operation of washing the product with about 5 liters of
deionized water and then filtering was repeated 5 times. The solid material obtained
upon the final filtration was dried at 120°C and then fired under a stream of air at 550°C
for 3 hours.
[0101]
Analysis of the resulting fired product by X-ray diffraction (apparatus model:
Rigaku RINTc2500V) confirmed that the product had an MFI strncture. Fmiher, X-ray
fluorescence analysis (apparatus model: Rigaku ZSXIO!e) revealed an Si0iAh03 ratio
(molar ratio) of65. Based on these results, the amount of aluminum element
incorporated within the lattice framework was calculated as 1.3 mass%.
[01 02]
Subsequently, a 30 mass% aqueous solution of ammonium nitrate was added to
the fired product in a ratio of 5 mL of the aqueous solution per I g of the obtained fired
, __
-,- -
""'·
45
product, and after heating at I 00°C with constant stirring for 2 hours, the mixture was
filtered and washed with water. This operation was repeated 4 times, and the product
was then dried at l20°C for 3 hours, yielding an ammonium-type MFI zeolite.
Subsequently, the product was fired at 780°C for 3 hours, yielding a proton-type MFI
zeolite.
(0103]
Next, in the first phosphorus treatment step, 30 g of the obtained proton-type MFI
zeolite was impregnated with 30 g of an aqueous solution of diammonium hydrogen
phosphate in order to suppmt 1.5 mass% of phosphorus (based on a value of 100 mass%
for the total mass of the proton-type MFI zeolite), and the resulting product was then
dried at l20°C. Subsequently, the product was fired under a stream of air at 780°C for 3
hours, yielding a phosphorus-treated crystalline aluminosilicate A.
(0104]
- Preparation of Alumino silicate (MFI Zeolite) Catalyst
An appropriate amount of pure water was added to the obtained phosphorustreated
crystalline aluminosilicate A and an alumina powder (Cataloid AP-I,
manufactured by JGC C&C, Ltd., Ah03 content: 71.7 wt%), and the resulting mixture
was kneaded to form a lumpy phosphorus-treated crystalline aluminosilicate/alumina
mixture. This mixture was processed into a circular cylindrical shape (diameter: 1.8 mm)
using an extrusion molding apparatus, and the extruded product was dried at l20°C and
then fired under a stream of air at 550°C for 3 hours. Then, in a second phosphorus
treatment step, the product was impregnated with 30 g of an aqueous solution of
phosphoric acid in order to support 1.5 mass% of phosphorus (based on a value of I 00
mass% for the total mass of the phosphorus-treated crystalline aluminosilicate/alumina
mixture), and the resulting product was dried at l20°C. Subsequently, the product was
46
fired under a stream of air at 780°C for 3 hours, yielding an aluminosilicate (MFI zeolite)
catalyst B. In this aluminosilicate catalyst, the weight ratio of phosphorus-treated
crystalline aluminosilicate/alumina was 90 mass%/! 0 mass%.
[0105]
Using the same preparation method as that described above for the
aluminosilicate catalyst B, a variety of catalysts B, C, D, E, E, F, G and H shown in
Table 3 were prepared by appropriate combinations ofthe amounts added of the various
components in the first phosphorus treatment step and the second phosphorus treatment
step.
[0106]
-Preparation of Phosphorus-Treated Crystalline Aluminosilicate (BEA Zeolite)
A first solution was prepared by dissolving 59.0 g of silicic acid (Si02: 89
mass%) in 202 g of an aqueous solution of tetraethylammonium hydroxide ( 40 mass%).
This first solution was added to a second solution prepared by dissolving 0. 74 g of AI
pellets and 2.69 g of sodium hydroxid~ in 17.7 g of water. By mixing the first solution
and the second solution in this manner, a reaction mixture with a composition (calculated
as a molar ratio of oxides) of2.4Na20-20.0(TEA)2-A!z03-64.0Si0z-612H20 was
obtained.
This reaction mixture was placed in a 0.3 L autoclave and heated at 150°C for 6
days. The thus obtained product was separated from the mother liquor and washed in
distilled water.
Based on the results of analysis of the thus obtained product by X-ray diffi"action
(apparatus model: Rigaku RINT-2500V), the XRD pattern confirmed that the product
was a BEA zeolite.
- 4TSubsequently,
following an ion exchange with an aqueous solution of ammonium
nitrate (30 mass%), the BEA zeolite was fired at 550°C for 3 hours, yielding a protontype
BEA zeolite.
[01 07]
Next, in the first phosphorus treatment step, 30 g of the proton-type BEA zeolite
was impregnated with 30 g of an aqueous solution of diammonium hydrogen phosphate
in order to support 2.0 mass% of phosphorus (based on a value of 100 mass% for the
total mass of the crystalline aluminosilicate), and the resulting product was then dried at
l20°C. Subsequently, the product was fired under a stream of air at 780°C for 3 hours,
yielding a phosphorus-treated crystalline aluminosilicate (BEA zeolite).
[0108]
-Preparation of Aluminosilicate (Containing MFI and BEA Zeolites)
A phosphorus-treated crystalline aluminosilicate (containing MFI and BEA
zeolites) obtained by mixing 1 part by mass of the aforementioned phosphoms-treated
crystalline aluminosilicate (BEA zeolite) and 9 parts by mass of the aforementioned
phosphoms-treated crystalline aluminosilicate B (MFI zeolite) and an alumina powder
(Cataloid AP-1, manufactured by JGC C&C, Ltd., Ah03 content: 71.7 wt%) were
kneaded together while an appropriate amount of pure water was added, thus forming a
lumpy phosphorus-treated crystalline aluminosilicate/alumina mixture. This mixture was
processed into a circular cylindrical shape (diameter: 1.8 mm) using an extrusion
molding apparatus, and the extruded product was dried at 120°C and then fired under a
stream of air at 5 50°C for 3 hours. Then, in a second phosphorus treatment step, the
product was impregnated with 30 g of an aqueous solution of phosphoric acid in order to
suppott 1. 5 mass% of phosphorus (based on a value of 100 mass% for the total mass of
the phosphorus-treated crystalline aluminosilicate/alumina mixture), and the resulting
48
product was dried at 120°C. Subsequently, the product was fired under a stream of air at
780°C for 3 hours, yielding an aluminosilicate catalyst I (containing both MFI zeolite
and BEA zeolites). In this aluminosilicate catalyst, the weight ratio of phosphorustreated
crystalline aluminosilicate/ahunina was 90 mass%/1 0 mass%.
[0109]
(Heat Treatment using Water Vapor ofMonocyclic Aromatic Hydrocarbon Production
Catalyst)
Using the catalyst B and the catalyst D described above, treatment of each
catalyst was performed in an atmosphere with a water vapor concentration of I 00% and a
heating temperature of 700°C for a treatment time of 15 minutes, thus preparing a
hydrothermally treated catalyst B-1 and a hydrothermally treated catalyst D-1 shown in
Table 3.
[0110]
[Tab1e3]
Catalysts
Catalyst name B c D E F G H I B-1 D-1
Amount of phosphorus
added in first phosphorus 1.5% l.O% 3.0% 1.5% 1.5% 1.5% 0% 2.0% 1.5% 3.0%
treatment step
Amount of phosphorus
added in second phosphorus l.S% 1.5% 1.0% 1.0% 2.5% 0.0% l.O% 1.5% 1.5% 1.0%
treatment step
Hydrothcnnal treatment step no no no no no no no no yes yes
[0 111]
The catalytic activity of each ofthe obtained catalysts in the initial reaction stage,
and the catalytic activity after hydrothermal degradation were evaluated in the following
matmer.
49
[0112]
[Initial Reaction Stage of Production of Monocyclic Aromatic Hydrocarbons Having a
Carbon Number of 6 to 8]
Using a flow-type reaction apparatus in which the reactor had been packed with
one of the above catalysts (I 0 ml), the hydrogenated light cycle oil A-1 or the
hydrogenated thermally cracked heavy oil B-1 was introduced into the reactor and
brought into contact with the catalyst and reacted under conditions including a reaction
temperature of 550°C, a reaction pressure of 0.1 MPaG, and a contact time between the
feedstock and the catalyst of25 seconds. As illustrated in Table 4, the various
combinations of the different feedstock oils and catalysts were deemed Examples I to 8
and Comparative Examples I and 2.
[OII3]
50
[Table 4]
(Reaction Results)
Example Example Example Example Example Example Example Example Example Example Comparative Comparati vc
1 2 3 4 5 6 7 8 9 10 Example 1 Example 2
hydrogenated
hydrogenated hydrogenated
hydrogenated
hydrogenated hydrogenated hydrogenated
hydrogenated
heavy
catalytic
hydrogenated
hydrogenated
Feedstock light cycle oil
thermally thermally
light cycle oil
thermally thermally thermally
light cycle oil
catalytic
reformer
thermally
light cycle oil
cracked cracked cracked cracked cracked racking cracked
A-1 A-1 A-1 heavy oil D A-1
heavy oil B-1 heavy oil B-1 heavy oil B-1 heavy oil B-1 heavy oil B-1 gasoline C heavy oil B-1
Catalyst B c D E F I D-1 B-1 B-1 B-1 G H
Catalyst state initial initial initial initial initial initial initial initial initial initial initial initial
BTX yield 31% 40% 38% 29% 40% 41% 39% 32% 40% 50% 32% 22%
~/
i;;;1
1'01
51
[0114]
Reaction was continued for 24 hours under the conditions shown in Table 4 to ·
produce monocyclic aromatic hydrocarbons having a carbon number of 6 to 8 (benzene,
toluene, xylene). The total mass of the thus obtained product was collected, and a
compositional analysis of the product was performed using an FID gas chromatograph to
evaluate the catalytic activity (recorded as initial reaction stage). The results of
evaluating the average BTX yield (benzene, toluene, xylene) when reaction was
performed for 24 hours are shown in Table 4.
[0115]
Based on the results shown in Table 4, it was evident that in Example 1 to
Example 6, in which reaction was performed using a catalyst that had been treated in the
first and second phosphorus treatment steps, monocyclic aromatic hydrocarbons having a
carbon number of6 to 8 (benzene, toluene, xylene) were able to be produced with better
efficiency than in Comparative Example I or Comparative Example 2 (comparative
examples using the same feedstocks) in which reaction was performed using a catalyst
that had not undergone treatment in either the first or second phosphorus treatment step.
Accordingly, by performing an appropriate level of phosphorus treatment in the
first and second phosphorus treatment steps, degradation of the crystalline
aluminosilicate and the alumina binder due to significant coke formation and adhesion
(accumulation) was able to be suppressed.
Further, it was also evident that in Example 7 and Example 8, in which the
hydrothermally treated catalysts B-1 and D-1 were used, monocyclic aromatic
hydrocarbons having a carbon number of6 to 8 (benzene, toluene, xylene) were able to
be produced with better efficiency than in Example I and Example 3, in which the
catalysts B and D that had not been hydrothermally treated were used. This confirmed
52
that by using a catalyst that had undergone an appropriate level of hydrothermal
treatment in advance, BTX was able to be produced with even better efficiency.
Fmihermore, it was also evident that in Examples 9 and 10, which used different
feedstocks from Examples 1 to 8, monocyclic aromatic hydrocarbons having a carbon
number of 6 to 8 (benzene, toluene, xylene) were still able to be produced with good
efficiency.
Accordingly, it was confirmed that in Examples 1 to 10, by using an
aluminosilicate catalyst that had been treated in the first and second phosphorus
treatment steps, BTX was able to be produced with good efficiency.
[0 116]
Among the above catalysts, the catalyst B, the catalyst B-1 and the catalyst H
were each subjected to simulated hydrothermal degradation by perfom1ing a
hydrothermal treatment under a 1 00 mass% water vapor atmosphere at a treatment
temperature of 650°C for a treatment time of 6 hours. This state following simulated
hydrothennal degradation was described as "after hydrothermal degradation", and using
the same method as that described above in [Initial Reaction Stage of Production of
Monocyclic Aromatic Hydrocarbons Having a Carbon Number of 6 to 8], each catalyst
was reacted with a feedstock oil, and the resulting product was subjected to
compositional analysis to evaluate the catalytic activity after hydrothermal degradation.
The evaluation results are shown in Table 5.
[0 I I 7]
53
[Table 5]
(Reaction Results)
Example II Example 12 Comparative Example 3
Hydrogenated thermally Hydrogenated thermally Hydrogenated thennally
Feedstock
cracked heavy oil B-1 cracked heavy oil B-1 cracked heavy oil B-1
Catalyst B Il-l H
after hydrothcnnal after hydrothermal after hydrothennal
Catalyst state initial initial initial
degradation degradation degradation
BTX yield 41% 39% 42% 40% 33% 25%
[0118]
As illustrated in Table 5, it was evident that compared with Comparative
Example 3, which used a catalyst that had not undergone treatment in either the first or
the second phosphorus treatment step, Example 11 and Example 12, in which reaction
was performed using an aluminosilicate catalyst that had been subjected to both the first
and second phosphorus treatment steps, exhibited a smaller reduction in the BTX yield
between the initial state and the state after hydrothermal degradation, and monocyclic
aromatic hydrocarbons having a carbon number of 6 to 8 (benzene, toluene, xylene) were
still able to be produced with g?od efficiency.
Accordingly, in Example 11 and Example 12 of the present invention, it was
confirmed that by using an aluminosilicate catalyst that had been subjected to both the
first and second phosphorus treatment steps, the hydrothermal stability increased and
catalyst degradation was able to be suppressed, meaning BTX was able to be produced
with good efficiency.
[0 119]
While preferred examples of the invention have been described above, the present
invention is in no way limited by these examples. Additions, omissions, substitutions,
54
and other modifications can be made without departing from the spirit or scope of the
present invention. Accordingly, the invention is not to be considered as being limited by
the foregoing description, and is only limited by the scope of the appended claims.
DESCRIPTION OF THE REFERENCE SIGNS
[0120]
I: Method for producing monocyclic aromatic hydrocarbons having a carbon number of
6 to 8
2: Hydrogenation reaction device
3: Dehydrogenation tower
4: Cracking and reforming reaction device
5: Refining and collection device
6: BTX fraction collection tower
7: Gas separation tower
8: Recycling line

CLAIMS
1. A method for'producing an aluminosilicate catalyst, comprising:
a first phosphorus treatment step of treating a crystalline aluminosilicate with a
first phosphorus compound,
a mixing and firing step of mixing a phosphorus-treated crystalline
aluminosilicate obtained in the first phosphorus treatment step with a binder, and then
performing firing to form an aluminosilicate mixture, and
a second phosphorus treatment step of treating the aluminosilicate mixture with a
second phosphoms compound.
2. The method for producing an aluminosilicate catalyst according to Claim 1,
wherein in the mixing and firing step, the phosphorus-treated crystalline aluminosilicate
and the binder are mixed and molded, and a thus obtained molded body is then fired.
3. The method for producing an aluminosilicate catalyst according to Claim 1,
wherein the crystalline aluminosilicate comprises at least one component selected from
the group consisting of medium pore zeolites and large pore zeolites as a main
component.
4. The method for producing an aluminosilicate catalyst according to Claim 1,
wherein the crystalline aluminosilicate is a pentasil zeolite.
56
5. The method for producing an aluminosilicate catalyst according to Claim I,
wherein the crystalline aluminosilicate is an MFI zeolite.
6. The method for producing an aluminosilicate catalyst according to Claim I,
wherein the binder comprises alumina.
7. The method for producing an aluminosilicate catalyst according to Claim I,
wherein phosphoric acid is used as the second phosphoms compound.
8. The method for producing an aluminosilicate catalyst according to Claim I,
wherein following the second phosphotus treatment step, a heat treatment is performed in
an atmosphere containing water vapor.
9. An aluminosilicate catalyst, obtained using the method for producing an
aluminosilicate catalyst according to any one of Claims 1 to 8.
I 0. A method for producing monocyclic aromatic hydrocarbons having a carbon
number of 6 to 8, the method comprising a cracking and reforming reaction step of
bringing a feedstock oil having a 10 vol% distillation temperature of at least 140°C and a
90 vol% distillation temperature of not more than 390°C into contact with a monocyclic
aromatic hydrocarbon production catalyst containing the aluminosilicate catalyst
according to Claim 9 packed in a fixed bed reactor, and reacting the feedstock oil to
obtain a product comprising monocyclic aromatic hydrocarbons having a carbon number
of6 to 8.
57
II. The method for producing monocyclic aromatic hydrocarbons having a carbon
number of 6 to 8 according to Claim 10, wherein in the cracking and reforming reaction
step, two or more fixed bed reactors are used, and the cracking and reforming reaction
and regeneration of the monocyclic aromatic hydrocarbon production catalyst are
repeated while periodically exchanging the fixed bed reactors.
12. The method for producing monocyclic aromatic hydrocarbons having a carbon
number of 6 to 8 according to Claim 10, wherein the feedstock oil is a light cycle oil or a
partially hydrogenated product of the light cycle oil.
13. The method for producing monocyclic aromatic hydrocarbons having a carbon
qumber of 6 to 8 according to Claim 10, wherein the feedstock oil is a thermally cracked
heavy oil obtained from an ethylene. production apparatus or a partially hydrogenated
product of the thermally cracked heavy oil.