•
5
SF-2442
1
DESCRIPTION
TITLE OF INVENTION: PROCESS FOR PRODUCING METHANOL
TECHNICAL FIELD
[0001]
The present invention relates to a process for producing
methanol from carbon dioxide and hydrogen as materials.
BACKGROUND ART
[0002]
Methanol is used as a material for products such as
10 dimethyl ether, MTBE (methyl tertiary butyl ether) and
petrochemical intermediates, and also as a fuel.
[0003]
In a conventional methanol production process, fossil
fuels such as hydrocarbons and cokes as materials are steam
15 reformed into a syngas (containing CO, H2 and a small amount
of C02), and the syngas is reacted as a main material to
synthesize methanol. Such a process relies on the use of fossil
materials as main ingredients. Thus, the process consumes
earth resources and increases the amount of C02 in the
20 atmosphere, thereby contributing to global warming.
[0004]
A known alternative technique is to synthesize methanol
from C02 and hydrogen as rnaterials. According to this process,
carbon dioxide that is a factor of global warming is converted
15
SF-2442
2
into the organic compound. Thus, this technique is highly
desirable not only in view of the fact that it contributes to
various chemical production activities but also from the
viewpoint of the reduction of carbon dioxide blamed for global
5 warming, namely, from the viewpoint of the prevention of global
warming.
[0005]
Due to the thermodynamic equilibrium of the reaction as
well as because the reaction is inhibited by water that is
10 by-produced together with methanol, synthesizing methanol from
a material gas with a high carbon dioxide content requires a
catalyst exhibiting a higher activity and a higher durability
than in the methanol synthesis from a syngas.
[0006]
With such needs, copper-containing multicomponent
catalysts such as copper/zinc oxide/aluminum oxide/zirconium
oxide and copper/zinc oxide/aluminum oxide/zirconium
oxide/gallium oxide have been developed (see, for example,
JP-A-H07-39755 (Patent Literature 1), JP-A-H06-312138 (Patent
20 Literature 2), and Applied Catalysis A: Gernal, 38, 311-318
(1996) (Non-Patent Literature 1) ). Further, JP-A-HI0-309466
(Patent Literature 3) discloses a highly active catalyst which
contains 0 . 3 to 0.9 wt% of silica derived from a colloidal silica
or a water-dissolved silica and which is prepared by calcination
SF-2442
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at 480 to 690°C.
[0007]
Because these catalysts are solid catalysts, the methanol
synthesis reaction is generally carried out with a fixed-bed
5 reactor. In general, the reactor may be a multitubular reactor.
In general, the reaction mode may be batchwise. It will also
be preferable to adopt a continuous reaction mode in which part
or all of unreacted materials (including carbon dioxide and
hydrogen) are recovered from the reaction mixture containing
10 methanol formed, and the unreacted material components are
circulated back to the material introduction step. In order
to separate the reaction mixture into methanol and the unreacted
gas, techniques such as distillation and separation with a
gas-liquid separator are known.
15 Citation List
Patent Literatures
[0008]
20
Patent Literature 1: JP-A-1995-39755
Patent Literature 2: JP-A-1994-312138
Patent Literature 3: JP-A-1998-309466
Non-Patent Literature
[0009]
Non-Patent Literature 1: Applied Catalysis A: Gernal, 38,
311-318 (1996)
SF-2442
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SUMMARY OF INVENTION
Technical Problem
[0010]
According to studies carried out by the present inventors,
5 methanol production from carbon dioxide and hydrogen has
suffered a decrease in reaction efficiency with time when
unreacted materials are recovered and reused as materials.
[0011]
It has been found that the above phenomenon is ascribed
10 partly to the degradation of the catalyst with time but is
attributed largely to the fact that the proportion of components
which are present in small amounts in the reaction materials
and do not react with the catalyst of the present application
(hereinafter, sometimes referred to as inert components) is
15 increased with time with the result that carbon dioxide and
hydrogen to be reacted with each other under catalysis of the
catalyst come to represent a smaller proportion relative to
the materials supplied to the reactor.
[0012]
20 It has been further found that the inert components
include compounds containing carbon and hydrogen, such as
methane. Furthermore, the present inventors have found that
hydrogen and carbon dioxide used as materials contain such inert
components in small amounts. That is, the progress of the
15
SF-2442
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methanol production reaction is accompanied by an increasing
proportion of the inert components and a consequent decreasing
concentration of the materials, thus leading to a decrease in
reaction efficiency.
5 [0013]
A possible approach to remedy this decrease in reaction
efficiency is to clear the reactor system of part or all of
the unreacted materials that have come to have a larger
proportion of the inert components. However, such an approach
10 causes a risk that the inert components such as methane are
released into the atmosphere. Methane is known to have a
greenhouse effect. Thus, this approach can adversely affect
the global environment.
[0014]
Accordingly, it is important that a methanol production
process be provided which can efficiently produce methanol from
carbon dioxide and hydrogen while suppressing loads to the
global environment. The present invention has been made in
order to address this problem.
20 Solution to Problem
[0015]
In view of the above problem, the present inventors have
carried out studies. As a result, they have found that methanol
can be produced with good efficiency and the above problem can
SF-2442
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be solved by providing a step in which part or all of unreacted
materials containing the inert components are combusted to
produce a combustion product and energy such as thermal energy,
and a step in which the combustion product from the above step
5 which contains carbon oxides such as carbon monoxide and carbon
dioxide is circulated again as a material. The present
invention has been completed based on this finding.
[0016]
A process for producing methanol according to the present
10 invention comprises a step (a) of reacting hydrogen and carbon
dioxide with each other in a reactor in the presence of a
copper-containing catalyst to produce a reaction mixture
containing methanol;
a step (b) of circulating part or all of the reaction
15 mixture to the step (a);
a step (c1) of combusting part of the reaction mixture
to produce a combustion product and energy, and a step (c2)
of circulating part or all of the combustion product to the
step (a), the step (c1) and the step (c2) being performed when
20 the reaction mixture contains a compound (p) containing carbon
and hydrogen except methanol at not less than 0.1 mol% (wherein
all components of the reaction mixture excluding methanol and
water represent 100 mol%); and
a step (d) of separating a component including methanol
SF-2442
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from the reaction mixture.
[0017]
The compound (p) is preferably inert to the
copper-containing catalyst.
5 [0018]
It is preferable that at least part of the compounds (p)
be a hydrocarbon, and more preferably methane. It is
particularly preferable that the compound (p) be methane.
[0019]
10 Preferably, the reaction mixture contains the compound
(p) at 0.1 to 50 mol%.
[0020]
The copper-containing catalyst is preferably a catalyst
containing copper, zinc, aluminum and silicon.
15 [0021]
The energy produced in the step (c1) is preferably energy
selected from thermal energy, electric energy and kinetic
energy, and is more preferably thermal energy.
Advantageous Effects of Invention
20 [0022]
According to the methanol production process of the
present invention, an increase in the proportion of inert
components, in detail, compounds containing carbon and
hydrogen except methanol, with time during the methanol
10
SF-2442
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production steps is addressed by combusting the compounds when
the concentration of the compounds reaches a specific
concentration, thereby reducing the amount of the inert
components or eliminating the inert components. Thus, the
5 methanol production process of the invention can suppress an
increase with time of the concentration of the inert components
present in the reaction system, thereby allowing for efficient
production of methanol.
[0023]
Further, according to the methanol production process of
the invention, the energy produced by combusting the compounds
can be recovered. Furthermore, according to the methanol
production process of the invention, carbon oxides such as
carbon monoxide and carbon dioxide resulting from the
15 combustion can be reused as materials for the production of
methanol.
[0024]
The methanol production process of the invention is of
great significance in industry also from the viewpoint of global
20 environment protection because the process allows for, in
addition to efficient methanol production, the reuse of carbon
oxides such as carbon monoxide and carbon dioxide resulting
from combustion.
Brief Description of Drawings
SF-2442
9
[0025]
[FIG. 1] FIG. 1 is a flowchart diagram illustrating a
system used in EXAMPLES.
[FIG. 2] FIG. 2 is a flowchart diagram illustrating a
5 system used in COMPARATIVE EXAMPLES.
DESCRIPTION OF EMBODIMENTS
[0026]
The present invention will be described in detail
hereinbelow.
10 [0027]
A process for producing methanol according to the present
invention includes a step (a) of reacting hydrogen and carbon
dioxide with each other in a reactor in the presence of a
copper-containing catalyst to produce a reaction mixture
15 containing methanol; a step (b) of circulating part or all of
the reaction mixture to the step (a); a step (cl) of combusting
part of the reaction mixture to produce a combustion product
and energy, and a step (c2) of circulating part or all of the
combustion product to the step (a), the step (cl) and the step
20 (c2) being performed when the reaction mixture contains a
compound (p) containing carbon and hydrogen except methanol
at not less than 0.1 mol% (wherein all the components of the
reaction mixture excluding methanol and water represent 100
mol%); and a step (d) of separating a component including
SF-2442
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methanol from the reaction mixture.
[0028]
The reactor is usually a fixed-bed reactor in which the
catalyst is packed in a fixed bed. In such a case, the reactor
5 includes a catalyst layer.
[0029]
The hydrogen and the carbon dioxide used in the invention
may be obtained by known methods without limitation. For
example, the hydrogen may be any known hydrogen such as hydrogen
10 generated (by-produced) by a steam reforming reaction,
hydrogen generated by electrolysis, or hydrogen obtained by
photolysis of water. For example, the carbon dioxide may be
one generated by any of various chemical reactions or by the
combustion of a fuel in petrochemical plants. It tends to be
15 substantially impossible for these hydrogen and carbon dioxide
to be free of compounds (p) containing carbon and hydrogen as
will be described later.
[0030]
In the step (a) of the inventive methanol production
20 process, carbon dioxide and hydrogen are reacted with each other
to synthesize methanol and water. The reaction mixture
obtained by the reaction contains methanol and water, and
usually further contains unreacted materials (for example,
hydrogen, carbon dioxide) and byproduct s (for example, carbon
• SF-2442
11
monoxide) .
components,
Further, the reaction mixture often contains inert
in detail, compounds (p) containing carbon and
hydrogen except methanol, for example hydrocarbons such as
methane and ethane.
5 [0031]
In the methanol production process of the invention,
generally, a component including methanol is separated from
the obtained reaction mixture. In detail, the unreacted
materials, the byproducts and the compounds (p) are separated
10 from the reaction mixture, thereby obtaining a mixture of
methanol and water as the component including methanol.
[0032]
Further, methanol is obtained usually by dehydrating the
mixture of methanol and water. The dehydration method is not
15 particularly limited and may be any of known methods such as
distillation.
[0033]
In the step (b) of the inventive methanol production
process, part or all of the reaction mixture is circulated to
20 the step (a). The part of the reaction mixture that is
circulated may be circulated in such a manner that the reaction
mixture obtained in the step (a) is directly circulated.
Alternatively, the residue after the separation of the
component including methanol from the reaction mixture, namely,
SF-2442
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the residue composed of the unreacted materials, the byproducts
and the compounds (p) may be circulated. Because the reaction
between hydrogen and carbon dioxide in the invention is an
equilibrium reaction, the latter case is preferable. That is,
5 it is preferable that the residue after the separation of
methanol be circulated. By performing the step (b) in this
manner, the reaction efficiency may be improved.
[0034]
In the present invention, hydrogen and carbon dioxide are
10 reacted in such a manner that hydrogen and carbon dioxide are
brought into contact with a catalyst described later to induce
the reaction. When hydrogen and carbon dioxide are brought
into contact with the catalyst, the molar ratio of hydrogen
to carbon dioxide (hydrogen/carbon dioxide) is preferably not
15 less than 2.5, and more preferably not less than 3.0. In the
case where a fixed-bed reactor is used in which the catalyst
is packed in a fixed bed, the hydrogen to carbon dioxide ratio
is more preferably not less than 3.5, and particularly
preferably not less than 4.0.
20 [0035]
The reaction between hydrogen and carbon dioxide to form
methanol takes place in accordance with the following reaction
formula.
[0036]
•
I SF-2442·
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3Hz + COz ~ CH30H + HzO
If the hydrogen to carbon dioxide molar ratio is below
the above range, methanol productivity is lowered as apparent
from the above reaction formula as well as from the fact that
5 the loss of pressure through the catalyst layer is so increased
in the case of a fixed-bed reactor that the equilibrium
conversion is decreased. The upper limit of the hydrogen to
carbon dioxide molar ratio at the contact with the catalyst
layer is not particularly limited. However, an excessively
10 high hydrogen to carbon dioxide molar ratio can result in a
decrease in methanol productivity. Thus, the upper limit of
the hydrogen to carbon dioxide molar ratio is preferably 20.0,
more preferably 10.0, still more preferably 6.0, particularly
preferably 5.5, and further preferably 5.0.
15 [0037]
In the methanol production process of the invention,
water is produced together with methanol. In general, water
is adsorbed onto a catalyst to inhibit the methanol forming
reaction, and thus can be a factor that decreases the efficiency
20 in methanol production. When the hydrogen to carbon dioxide
ratio is high, for example 3.5 or more, the supply of hydrogen
relative to that of carbon dioxide is large and consequently
the formed water is diluted to a lower water concentration than
a conventional level. Because a decrease in water
, SF-2442
14
concentration leads to a smaller amount of water adsorbed onto
a catalyst, such a molar ratio suppresses a decrease in methanol
production efficiency caused by water. This is probably the
reason why the inventive methanol production process performed
5 under the above conditions achieves a high efficiency in
methanol production.
[0038]
In the methanol production process of the invention,
hydrogen and carbon dioxide are reacted with each other in the
10 presence of a copper-containing catalyst. The
copper-containing catalyst may be any of known catalysts
without limitation as long as the catalyst contains copper and
can catalyze the reaction between hydrogen and carbon dioxide
into methanol.
15 [0039]
Preferred examples of the copper-containing catalysts
for use in the invention include catalysts described in Patent
Literature 3 which contain copper, zinc, aluminum and silicon
as essential components and have zirconium, palladium and
20 gallium as optional components. The copper-containing
catalyst used in the invention is preferably a catalyst
containing copper, zinc, aluminum and silicon, and is more
preferably a catalyst containing copper, zinc, aluminum and
silicon as well as at least one metal selected from zirconium,
, SF-2442
palladium and gallium.
15
These catalysts containing copper and
other components may be suitably used in the methanol production
process of the invention for reasons such as a small decrease
in activity by water which is by-produced during the production
5 of methanol from carbon dioxide.
[0040]
The copper-containing catalyst preferably has a particle
diameter of 0.5 to 20 rom, more preferably 1 to 20 rom, still
more preferably 2 to 20 rom, even more preferably 3 to 20 rom,
10 further preferably 3 to 15 rom, and particularly preferably 3
to 10 rom. This particle diameter of the copper-containing
catalyst ensures not only that the catalyst is handled easily
but also that the occurrence of a pressure loss is suppressed
when methanol is produced by the inventive method using a
15 catalyst layer in which the catalyst is packed in a fixed bed.
The catalyst having the above particle diameter may be produced
by any of known methods without limitation. A tableting method
is suitably used.
[0041]
I
20 The reactor used in the step (a) of the inventive
production process may be any of known reactors without
limitation. For example, it is preferable that the
copper-containing catalyst be packed in a fixed-bed reactor.
Alternatively, a radial flow reactor may be suitably used.
SF-2442
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Because the inventive process can decrease a pressure loss,
good productivity is obtained even with a relatively large
radial flow reactor, thus providing a possibility of efficient
methanol production.
5 [0042]
In a preferred embodiment for carrying out the step (a)
of the inventive production process, hydrogen and carbon
dioxide are reacted with each other in a reactor which has a
catalyst layer formed of the copper-containing catalyst. In
10 the reaction, hydrogen and carbon dioxide are supplied from
upstream of the catalyst layer in the reactor, and a reaction
mixture containing methanol is obtained from downstream of the
catalyst layer. The thickness of the catalyst layer in the
reactor is preferably not less than 1 m. The thickness of the
15 catalyst layer is preferably not less than 2 m, more preferably
not less than 3 m, and still more preferably not less than 4
m. Specifying the upper limit of the thickness does not have
any positive significance. However, the catalyst layer with
an excessively large thickness tends to have a large adverse
20 effect in terms of pressure loss. Thus, the upper limit is
preferably 20 m, and more preferably 15 m. The thickness of
the catalyst layer is not necessarily determined by the
positional relationship between the upstream side and the
downstream side, but means a substantial length determined in
10
SF-2442
17
consideration of the shape of the catalyst layer. It is not
necessary that the thickness of the catalyst layer be identical
at any given positions. It is preferable that substantially
the thinnest portion satisfy the above thickness. When the
5 catalyst layer has a thinner portion, it is probable that
material gases such as carbon dioxide and hydrogen be
concentrated at that portion relative to the other portions
and the apparent catalytic efficiency be lowered.
[0043]
The catalyst layer in the inventive methanol production
process is not particularly limited as long as it allows
hydrogen and carbon dioxide to be contacted with each other
and also with the catalyst. For example, the catalyst layer
may be a massive layer or may be formed of a plurality of
15 particles or powder. The catalyst layer is preferably formed
by packing the copper-containing catalyst with a particle
diameter of 3 to 20 mm, namely, particles of the catalyst in
the reactor. Further, the methanol production process of the
invention may involve a plurality of catalyst layers.
20 [0044]
The reactor may be disposed vertically or horizontally
in any direction. It is needless to mention that the reactor
may be shaped like a vessel or a curved pipe. However, it is
preferable that the reactor have a substantially linear tube
• SF-2442
18
shape. The upstream and the downstream may be arranged in any
5
positional relationship. For example, the reactor may be a
downflow reactor or an upflow reactor.
[0045]
The inventive production process includes the step (b)
in which part or all of the reaction mixture is circulated to
the step (a). Preferably, the reaction mixture is returned to
the step (a) in such a manner that part or all of methanol and
water are separated from the reaction mixture and the residue
10 is returned to the step (a). The residue usually contains
unreacted materials (for example, hydrogen, carbon dioxide)
and byproducts (for example, carbon monoxide). Further, the
residue usually contains inert components, in detail compounds
(p) containing carbon and hydrogen except methanol, for example
15 hydrocarbons such as methane and ethane, and may further contain
part of methanol and water.
[0046]
Production of methanol is considered in which a reaction
mixture containing methanol is obtained from hydrogen and
20 carbon dioxide and the reaction mixture is subjected to a step
in which unreacted materials in the reaction mixture are
returned to the reaction step (hereinafter, this returning is
referred to as recycle step) (the recycle step corresponding
to the step (b) in the inventive production process). In such
SF-2442
19
a process, the reaction mixture will contain little inert
components when hydrogen and carbon dioxide used as materials
are of high purity. Therefore, it may be considered that
performing the recycle step will not cause a decrease in
5 reaction efficiency due to the inert components. In fact,
however , it is substantially impossible for the reaction system
to be free of highly stable gases such as nitrogen or compounds
(p) containing carbon and hydrogen which may be present in the
hydrogen and the carbon dioxide as the materials. Such
10 compounds (p) containing carbon and hydrogen which are possibly
found in the hydrogen and the carbon dioxide as the materials
are, for example, hydrocarbons such as methane, ethane and
propane, and most probably methane. This methane often
originates from hydrogen as the material. The reason for this
15 is probably because steam reforming of methane is a typical
industrial process of hydrogen production. Such compounds do
not react with the copper-containing catalyst used in the step
(a), and therefore tend to increase their concentrations when
the recycle step is repeated. An increase in their
20 concentrations is considered to lead to a decrease in the
concentrations of hydrogen and carbon dioxide as the reaction
materials as well as to a decrease in methanol productivity.
It is needless to mention that the types of compounds (p)
containing carbon and hydrogen which may be found in the
SF-2442
20
reaction system can vary in accordance with the origins of the
hydrogen and the carbon dioxide as the materials.
[0047]
In such a case, a possible remedy is to purge part or all
5 of the gas to be returned to the reaction step so as to increase
the concentration of hydrogen and carbon dioxide. However,
this purge gas should not be released into the atmosphere
because the hydrocarbons such as methane are known to have a
strong greenhouse effect.
10 [0048]
Another possible approach to avoid the above problem is
to increase the purities of hydrogen and carbon dioxide
beforehand. However, this approach entails a separate
facili ty and the facility has to be large-scaled as the target
15 purities of hydrogen and carbon dioxide are higher, thus leading
to an increase in fixed costs.
[0049]
The process for producing methanol according to the
present invention includes a step (cl) of combusting part of
20 the reaction mixture to produce a combustion product and energy,
and a step (c2) of circulating part or all of the combustion
product to the step (a). These steps are performed when the
concentration of the inert components has increased, namely,
when the reaction mixture formed in the step (a) comes to contain
.. SF-2442
21
compounds (p) containing carbon and hydrogen except methanol
at not less than 0.1 mol% (wherein all the components of the
reaction mixture excluding methanol and water represent 100
mol%) .
5 [0050]
The step (c1) may be performed such that part of the
reaction mixture which contains compounds (p) containing
carbon and hydrogen except methanol at not less than 0.1 mol%
is combusted directly, or may be performed such that part or
10 all of such components as methanol and water are separated from
the reaction mixture and the residue is combusted.
Alternatively, the step may be performed such that components
such as hydrogen and carbon oxides are separated from the
reaction mixture and the residue is combusted.
15 [0051]
The reaction mixture usually contains not only the
components (p) but also hydrogen and carbon oxides. Performing
the step (c1) such that hydrogen is combusted can result in
a decrease in the reaction efficiency in methanol production
20 or can cause a possibility for the formed water to be circulated
to the step (a). The circulation of water to the step (a) is
preferably avoided as much as possible in view of the durability
of the catalyst.
[0052]
5
SF-2442
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If possible, the carbon oxides are preferably prevented
from undergoing the step (c1) because the carbon oxides can
cause a decrease in combustion efficiency.
[0053]
For example, hydrogen may be removed before the step (c1)
by a so-called cryogenic separation method utilizing the fact
that hydrogen is a light-boiling fraction, or by an adsorption
desorption method in which part or all of the reaction mixture
is subj ected to pressure swing separation or in which hydrogen
10 is separated by contact with, for example, a hydrogen storage
alloy. For example, the carbon oxides may be removed by being
absorbed by water or a basic aqueous solution.
[0054]
In the step (c2), the combustion product is circulated
15 to the step (a). Preferably, the combustion product that is
circulated includes carbon oxides such as carbon monoxide and
carbon dioxide.
[0055]
The combustion product formed in the step (c1) may be
20 directly returned to the step (a). Alternatively, the
combustion product may be circulated in such a manner that the
carbon oxides in the combustion product are absorbed by, for
example, alkaline water to separate typical inert components
such as nitrogen and the alkaline water which has absorbed the
10
SF-2442
23
carbon oxides is treated by heating or the like to recover the
carbon oxides, which are then returned to the step (a). In the
case where the reaction mixture obtained in the step (a) has
a high nitrogen content, it is useful to separate nitrogen by
5 the above method. Ifnitrogen is separated, the nitrogen gas
may be released into the atmosphere. Nitrogen does not
allegedly contribute to a greenhouse effect and is considered
to cause little loads to the environment.
[0056J
The steps (c1) and (c2) are carried out when the reaction
mixture contains compounds (p) containing carbon and hydrogen
except methanol at not less than 0.1 mol%, preferably not less
than 0.2 mol% (wherein all the components of the reaction
mixture excluding methanol and water represent 100 mol%). If
15 the concentration of the compounds (p) is less than the above
range, a decrease in reaction efficiency is small even when
the compounds (p) are returned as such to the step (a). If the
steps (c1) and (c2) are performed while the concentration of
the compounds (p) is below the above range, the amount of energy
20 recovered is small relative to the amount of energy required
to perform the steps (c1) and (c2), namely, the efficiency in
energy recovery is low.
[0057]
The steps (c1) and (c2) are performed at any upper-limit
I
SF-2442
24
concentration of the compounds (p) without limitation. The
reaction mixture usually contains compounds (p) containing
carbon and hydrogen except methanol at not more than 50 mol%,
preferably not more than 40 mol%, and more preferably not more
5 than 30 mol% (wherein all the components of the reaction mixture
excluding methanol and water represent 100 mol%). Any
concentration of the compounds (p) exceeding the above range
indicates that the reaction efficiency in the step (a) has been
so markedly lowered that the decrease in reaction efficiency
10 may not be fully complemented even by recovering energy and
circulating the combustion product by performing the steps (c1)
and (c2).
[0058]
The process for producing methanol according to the
15 present invention usually includes a step of measuring the
content of the compounds (p) in the reaction mixture. To
perform the measurement, the reaction mixture obtained in the
step (a) may be analyzed directly. When the reaction mixture
has been subj ected to separation, the analysis may be performed
20 at a plurality of points to determine the content of the
compounds (p) in the reaction mixture. For example, the
content of the compounds (p) in the reaction mixture may be
obtained based on the results of analysis at three points "d",
"e" and "f" in EXAMPLES described later.
II
5
SF-2442
25
[0059]
In the invention, the part of the reaction mixture
subjected to the step (c1) preferably represents not less than
0.5 mol%, more preferably not less than 0.8 mol%, and still
more preferably not less than 1 mol% of the reaction mixture
(wherein all the components of the reaction mixture excluding
methanol and water represent 100 mol%). On the other hand, the
proportion of the reaction mixture subjected to the step (c1)
is preferably not more than 20 mol%, more preferably not more
10 than 15 mol%, and particularly preferably not more than 12 mol%.
[0060]
If the proportion is excessively smaller than the lower
limit, the energy recovery efficiency may be lowered. If the
proportion is excessively high, the amount of the combustion
15 of hydrogen in the reaction mixture is so increased that the
reaction efficiency can be lowered as a result.
[0061]
In the present invention, it is not always necessary to
perform the steps (c1) and (c2), and 100 mol% of the reaction
20 mixture may be subjected to the step (b) (wherein all the
components of the reaction mixture excluding methanol and water
represent 100 mol%) .
[0062 ]
In the case where the content of components (typically
SF-2442
26
nitrogen) other than hydrogen, hydrocarbons and components (p)
in the reaction mixture exceeds a specific value, preferably
20 mol%, it is sometimes preferable to purge part or all of
such components into the atmosphere.
5 [0063]
According to the methanol production process of the
invention, methanol can be produced stably using usual hydrogen
and carbon dioxide as materials, namely, without the need of
the use of highly purified hydrogen and carbon dioxide obtained
10 through high-standard purification steps. That is, methanol
is produced while the inert components are removed from the
materials by performing the steps (cl) and (c2) in accordance
with the concentration of the compounds (p). As a result,
methanol can be produced as stably as or more stably than when
15 methanol is produced using high-purity hydrogen and
high-purity carbon dioxide. Further, according to the step
(cl) in the invention, energy can be obtained by combusting
part of the reaction mixture and the resultant combustion
product can be used as a material for the production of methanol.
20 [0064]
It has often been the case that the compounds (p) described
above are released as exhaust gases into the atmosphere or are
disposed of after a simple detoxification step such as
incineration. The former case and the latter case lead to
SF-2442
27
releasing of greenhouse gases into the atmosphere. In contrast,
the methanol production process of the invention utilizes such
components, for example the compounds (p), as an energy source
for obtaining energy such as combustion heat, and further
5 utilizes carbon oxides that are the combustion product from
the combustion of the compounds (p) as materials for methanol
production. As already mentioned, methane, which is a typical
example of the compounds (p), is known as a stronger greenhouse
gas than carbon dioxide. Thus, the present invention
10 unexpectedly achieves not only the suppression of the
greenhouse effects of carbon dioxide which has been one of the
main objectives, but also the suppression of the greenhouse
effects of other greenhouse gases. It can be said that this
advantageous effect is achieved because the reaction of
15 interest in the invention is the reaction of carbon oxide and
hydrogen into methanol.
[0065]
In the methanol production process of the invention, part
of the reaction mixture is combusted in the step (cl) to produce
20 a combustion product and energy. In this step, the energy may
be recovered by a method in which the energy is obtained in
the form of thermal energy wi th a combination of a reactor such
as a conventional combustion furnace and a heat exchanger, a
method in which the above-obtained thermal energy is converted
SF-2442
28
into electric energy similarly to thermal power generation,
or a method in which the energy is recovered as kinetic energy
with an internal combustion engine or a similar engine. Of
these methods, it is preferable to adopt a method capable of
5 recovering the energy as thermal energy. When the energy is
recovered as kinetic energy, it is preferable that the compounds
(p) be hydrocarbons having 2 or more carbon atoms such as ethane,
propane, butane, hexane and octane.
[0066]
10
15
20
According to the methanol production process of the
invention, methanol can be produced stably with a high
production efficiency while suppressing the influences of the
purities of the materials.
[0067]
In the methanol production process of the invention, the
step (a) is usually performed at a reaction temperature of 150
to 300°C, a reaction pressure of 1 to 10 MPa-G, and a GHSV (gas
hourly space velocity) of 1000 to 30000 hr-1
•
[0068]
For example, the step (a) in the methanol production
process may be preferably performed by a so-called upflow method
or downflow method using the catalyst layer. Such a method may
be carried out using a reactor having the catalyst layer as
mentioned above. For example, the reactor may have spaces both
SF-2442
29
upstream and downstream from the catalyst layer, or may be
configured such that the upstream side of the catalyst layer
is directly connected to a material supply line and the
downstream side of the catalyst layer is directly connected
5 to the exit of the reactor (a reaction product collection line) .
[0069]
In the methanol production process of the invention, it
is preferable that hydrogen and carbon dioxide be reacted wi th
each other in a reactor having the catalyst layer. The reaction
10 mixture obtained from the exit of the reactor usually contains
unreacted hydrogen and carbon dioxide and byproduct carbon
monoxide in addition to methanol and water produced by the
reaction. The reaction mixture is usually obtained as a gas.
That is, the reaction mixture is preferably a gaseous reaction
15 mixture.
[0070]
The methanol production process of the invention includes
a step (d) of separating a component including methanol from
the reaction mixture. The step (d) is usually carried out by
20 separating a component including methanol from the gaseous
reaction mixture.
[0071]
The gaseous reaction mixture is usually cooled and
thereafter separated into a liquid mixture and a gaseous mixture
SF-2442
30
with a gas liquid separator. This separation is usually
performed at a pressure of 0 to 10 MPa-G and a temperature of
-10 to 50°C. The separation with a gas liquid separator may
be performed multiple times, and may be carried out plural times
5 under different conditions. The liquid mixture obtained by the
separation corresponds to the component including methanol and
is formed of methanol, water and carbon dioxide dissolved
therein. The gaseous mixture includes the unreacted materials,
byproduct carbon monoxide and the compounds (p). At least part
10 of the gaseous mixture is circulated back to the reactor through
the step (b) and the steps (cl) and (c2).
[0072]
As mentioned above, the gaseous mixture may contain
byproduct carbon monoxide. Carbon monoxide may be supplied to
15 the reactor as an impurity in the materials.
[0073]
The methanol production process of the invention is
characterized by reusing the inert components. This
characteristic provides significant effects when the process
20 is performed on a large scale because the greenhouse effects
are limited even if gaseous inert components are released into
the atmosphere on a small scale as well as because the amount
of energy produced by small-scale combustion is small and the
energy recovery efficiency will be low.
St'-2442
31
[0074]
Thus, the inventive methanol production process is
substantially performed on such a large scale that the energy
by combustion can be efficiently recovered. The use of a
5 multitubular reactor is preferable from the viewpoint of
temperature control such as heat removal. In the case where
such a multitubular reactor is used in combination with a
fixed-bed catalyst layer, the scale of the catalyst layer per
tube is preferably not less than 1 L, more preferably not less
10 than 5 L, and still more preferably not less than 10 L.
Specifying the upper limit does not have any essential
significance. However, it is usually preferable that the scale
be not more than 30 L. Regarding the scale of the catalyst
layers combined, the upper limit is preferably 500 m3
, more
15 preferably 400 m3
, still more preferably 200 m3
, and
particularly preferably 150 m3
, and the lower limit is
preferably 1 m3
, more preferably 10 m3
, and still more preferably
20 m3
• A scale in this range ensures a high energy recovery
efficiency and is preferable also from the viewpoint of reaction
20 control.
[0075]
The catalyst layer is frequently used in combination wi th
a temperature control tank shaped like, for example, a jacket.
A single catalyst layer may be combined wi th such a temperature
SF-2442
32
control tank. Alternatively, a plurality of catalyst layers
may be stored in one temperature control tank; namely, a
multitubular system may be adopted. Such a multitubular system
is preferably used for industrial implementation.
5 [0076]
As a matter of course, the scale of the reactor is not
less than that of the catalyst layers.
[0077]
In the methanol production process of the invention, the
10 reaction may be terminated by a known method without limitation.
In detail, the reaction may be preferably terminated in such
a manner that without purging the residual gas in the reaction
system with an inert gas or the like, the supply of the material
mixture gas is switched to the supply of hydrogen so as to allow
15 hydrogen to react with carbon monoxide and carbon dioxide
remaining in the reaction system under similar conditions to
those described above, thereby converting substantially the
entirety of such residual materials into methanol.
[0078]
20 An embodiment of the methanol production process
according to the invention will be described below with
reference to FIG. 1. Hydrogen as a material gas is passed
through a purification device 2 where mainly water and fine
powdery solids are to be removed. On the other hand, carbon
SF-2442
33
dioxide is passed through a purification device 1 where mainly
water, fine powdery solids and impurities affecting the
reaction of interest in the invention are to be removed.
Thereafter, these material gases are mixed with each other wi th
5 a predetermined molar ratio (hydrogen/carbon dioxide). The
mixture is pressurized to an appropriate pressure with a booster
compressor 3, heated to an appropriate temperature with a heater
4, and fed to a reaction circulation system. The material
mixture gas that has entered the reaction circulation system
10 is led to a reactor 5 and is subj ected to a methanol synthesis
reaction. The reactor includes a catalyst layer formed of the
copper-containing catalyst. In the reactor 5, hydrogen and
carbon dioxide are reacted with each other to form a gaseous
reaction mixture containing methanol. The gaseous reaction
15 mixture (the reaction mixture gas) discharged from the reactor
5 is cooled to normal temperature or below with a condenser
6, where mainly the formed methanol and water are liquefied.
The mixture is then led to gas liquid separators 7 and 8. After
the mixture is separated into a liquid mixture containing
20 methanol and water, and a gaseous mixture in the gas liquid
separators 7 and 8, these mixtures are each withdrawn and water
and methanol are further separated from each other. A major
proportion of the gaseous mixture is circulated to the reactor
5 with a circulation compressor 9. When the concentration of
SF-2442
34
compounds (p) has exceeded a predetermined concentration, at
least part of the gaseous mixture is led to an apparatus 10
equipped with a combustion device and a heat recovery device.
In the apparatus 10, the gaseous mixture is combusted and the
5 heat is recovered. The combustion product is then circulated
to the reactor 5. In the case where the gas supplied from the
apparatus 10 contains components such as nitrogen which do not
participate in the combustion reaction, such components may
be separated and released into the atmosphere.
10 [0079]
Although not illustrated in FIG. 1, the liquid mixture
withdrawn from the gas liquid separators 7 and 8 may be
appropriately treated so as to separate components such as
carbon dioxide dissolved in the liquid mixture. In such a case,
15 the separated gas may be discharged from the system or may be
returned to the reaction circulation system.
EXAMPLES
[0080]
The present invention will be described in greater detail
20 by presenting examples hereinbelow without limiting the scope
of the invention.
[0081]
A system illustrated in FIG. 1 was used in EXAMPLES. The
system included a carbon dioxide purification device 1 for
• SF-2442
35
purifying carbon dioxide as a material, a hydrogen purification
device 2 for purifying hydrogen as a material, a booster
compressor 3 for supplying a mixture gas, a heater 4 for heating
the mixture gas, a reactor 5 for performing the reaction, a
5 condenser 6 for cooling a reaction mixture, gas liquid
separators 7 and 8 for separating the reaction mixture into
a liquid and a gas, a circulation compressor 9 for circulating
at least part of the separated gas to the reactor 5, and an
apparatus 10 for combusting at least part of the separated gas
10 and recovering the combustion heat.
[0082]
[PRODUCTION EXAMPLE 1]
(Preparation of copper-containing catalyst)
A catalyst was prepared substantially in accordance with
15 the method described in EXAMPLE 1 of Patent Literature 3
(JP-A-HI0-309466) .
[0083]
The composition of the catalyst was CuO: 45.2 wt%, ZnO:
27.1 wt%, A1203: 4.5 wt%, Zr02: 22.6 wt% and Si02: 0.6 wt%.
20 [0084]
[EXAMPLE 1]
With the use of the system illustrated in FIG. 1, the
reaction was performed for 24 hours after a steady state was
reached under the following conditions.
•
5
SF-2442
36
[0085]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 hr-1
Catalyst packing scale: 16.6 L
The composition, the temperature and the pressure were
measured at analytical points ("a" to "f") in FIG. 1 with a
process gas chromatograph, a thermometer and a pressure meter.
[0086]
10 During the operation, methane which was probably present
in the material hydrogen and corresponded to a compound (p)
defined in the present invention accumulated, and a 8 mol%
portion of a gas (a gaseous mixture) separated in the gas liquid
separator 7 and the gas liquid separator 8 was introduced into
15 the apparatus 10 in FIG. 1. (Hereinafter, this introduction
will be sometimes referred to as recycle gas purging. The
recycle gas purging rate in this case is 8 mol%.) The
introduced gas was then combusted and the heat was recovered.
The resultant gas containing carbon oxides was returned to the
20 reaction step. The steady state was considered to have been
reached when the methane concentration at the point "b" became
5.7 mol% and the methane concentration at the point "d" became
17 mol% (wherein all the components of the gas excluding
methanol and water represented 100 mol%) during the above
SF-2442
37
operation. The measurement results are described in Table 1.
[0087]
[Table 1]
Table 1
a b c d e f
H2/(kmol/hr) 0.00 1.14 5.12 3.98 0.35 0.00
C02/(kmol/hr) 0.30 0.34 1.07 0.73 0.07 0.00
col (kmol/hr) 0.00 0.00 0.13 0.13 0.01 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.20 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.09 1.08 0.99 0.09 0.00
N2/(kmol/hr) 4.43 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 4.93 1. 59 7.45 5.86 0.52 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
5 [0088]
In the above methanol production process, the methanol
conversion based on C02 usedwas 88 mol%, and the methanol output
per unit volume of the catalyst was 16 mol-methanol/L-Cat/hr.
The amount of heat recovered at the combustion heat recovery
10 device was 480 MJ/mol-methanol.
[0089]
[EXAMPLE 2]
The reaction was performed for 24 hours in the same manner
as in EXAMPLE 1 after a steady state was reached under the
15 following conditions.
[0090]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
5
SF-2442
38
GHSV: 10000 hr-1
Catalyst packing scale: 14.5 L
Methane concentration at point "b": 1.3 mol%
[0091]
Methane concentration at point "d": 3.4 moll
Recycle gas purging rate: 8 mol%
The results of measurements at the points "a" to "f" are
described in Table 2.
[0092]
10 [Table 2]
Table 2
a b c d e f
H2/(kmol/hr) 0.00 1.14 5.12 3.98 0.35 0.00
C02/(kmol/hr) 0.30 0.34 1.07 0.73 0.07 0.00
CO/(kmol/hr) 0.00 0.00 0.13 0.13 0.01 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.20 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.02 0.19 0.17 0.02 0.00
N2/(kmol/hr) 4.43 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 4.93 1. 52 6.56 5.04 0.45 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
[0093]
The methanol conversion based on CO2 used was 88 moll,
and the methanol output per unit volume of the catalyst was
15 18 mol-methanol/L-Cat/hr. The amount of heat recovered at the
combustion heat recovery device was 310 MJ/mol-methanol.
[0094 ]
[EXAMPLE 3]
5
10
SF-2442
39
The reaction was performed for 24 hours in the same manner
as in EXAMPLE 1 after a steady state was reached under the
following conditions.
[0095]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 hr-1
Catalyst packing scale: 14.5 L
Methane concentration at point "b": 0.1 mol%
Methane concentration at point "d": 0.3 mol%
Recycle gas purging rate: 8 mol%
The results of measurements at the analytical points (" a"
to "f") in FIG. 1 are described in Table 3.
[0096]
15 [Table 3]
Table 3
a b c d e f
H2/(kmol/hr) 0.00 1.14 5.12 3.98 0.35 0.00
C02/(kmol/hr) 0.30 0.34 1. 07 0.73 0.07 0.00
CO/(kmol/hr) 0.00 0.00 0.13 0.13 0.01 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.20 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.001 0.014 0.013 0.001 0.00
N2/(kmol/hr) 4.43 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 4.93 1. 501 6.384 4.883 0.43 0.55
Temperature/oC 25 25 25 25 25 25
Pressure!MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
[0097]
The methanol conversion based on C02 used was 88 mol%,
SF-2442
40
and the methanol output per unit volume of the catalyst was
18 mol-methanol/L-Cat/hr. The amount of heat recovered at the
combustion heat recovery device was 280 MJ/mol-methanol.
[0098]
5 [COMPARATIVE EXAMPLES]
A system illustrated in FIG. 2 was used in COMPARATIVE
EXAMPLES. The system included a carbon dioxide purification
device 1 for purifying carbon dioxide as a material, a hydrogen
purification device 2 for purifying hydrogen as a material,
10 a booster compressor 3 for supplying a mixture gas, a heater
4 for heating the mixture gas, a reactor 5 for performing the
reaction, a condenser 6 for cooling a reaction mixture, gas
liquid separators 7 and 8 for separating the reaction mixture
into a liquid and a gas, and a circulation compressor 9 for
15 circulating at least part of the separated gas to the reactor
5. Part of the gas in the system was discharged downstream from
the analytical point "e" to the outside without combusting the
gas or recovering the heat. (This corresponded to recycle gas
purging. )
20 [0099]
[COMPARATIVE EXAMPLE 1]
With the use of the system illustrated in FIG. 2, the
reaction was performed for 24 hours in the same manner as in
EXAMPLE 1 after a steady state was reached under the following
5
10
SF-2442
41
conditions, except that part of the gas was discharged (recycle
gas purged) from the system.
[0100]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 hr"
Catalyst packing scale: 16.6 L
Methane concentration at point "b": 5.6 molt
Methane concentration at point "d": 17 molt
Recycle gas purging rate: 8 molt
The resul ts of measurements at the analytical points (" a"
to "f") in FIG. 2 are described in Table 4.
[0101]
[Table 4]
II
II
I
15 Table 4
a b c d e f
H2/(kmol/hr) 0.00 1.14 5.12 3.98 0.35 0.00
C02/(kmol/hr) 0.36 0.34 1. 07 0.73 0.07 0.00
CO/(kmol/hr) 0.00 0.00 0.13 0.13 0.01 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.24 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.09 1.08 0.99 0.09 0.00
N2/(kmol/hr) 5.43 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 6.03 1. 59 7.45 5.86 0.52 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
[0102]
The methanol conversion based on CO2 used was 72 molt,
and the methanol output per unit volume of the catalyst was
JIii
1
SF-2442
42
16 mol-methanol/L-Cat/hr.
[0103]
The methanol conversion was lower than those in EXAMPLES.
As a matter of course, the amount of recovered heat was zero.
5 These results are probably because hydrogen and carbon dioxide
as well as methane were discharged to the outside of the system
and consequently there occurred no conversion of
methane-derived carbon dioxide into methanol.
[0104]
10 [COMPARATIVE EXAMPLE 2]
with the use of the system illustrated in FIG. 2, the
reaction was performed for 24 hours in the same manner as in
COMPARATIVE EXAMPLE 1 after a steady state was reached under
the following conditions.
15 [0105]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 hr-1
Catalyst packing scale: 28.5 L
20 Methane concentration at point "b": 4.9 mol%
Methane concentration at point "d": 49 molt
Recycle gas purging rate: 1 mol%
The results of measurements at the analytical points (" a"
to "f") in FIG. 2 under the steady state are described in Table fIfl II
'I
SF-2442
43
5.
[0106]
[Table 5]
Table 5
a b c d e f
H2/ (kmol/hr) 0.00 0.85 5.12 4.27 0.06 0.00
C02/(kmol/hr) 0.30 0.29 1. 07 0.78 0.01 0.00
CO/(kmol/hr) 0.00 0.00 0.14 0.14 0.00 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.20 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.06 5.00 4.94 0.06 0.00
N2/(kmol/hr) 4.58 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 5.08 1. 22 11. 38 10.16 0.13 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
5 [0107]
The methanol conversion based on C02 used was 86 mol%,
and the methanol output per unit volume of the catalyst was
9 mol-methanol/L-Cat/hr.
[0108]
10 [COMPARATIVE EXAMPLE 3]
With the use of the system illustrated in FIG. 2, the
reaction was performed for 24 hours in the same manner as in
COMPARATIVE EXAMPLE 1 after a steady state was reached under
the following conditions.
15 [0109]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 hr-1
1
rl
'I
II
\I
I
I
5
SF-2442
44
Catalyst packing scale: 14.5 L
Methane concentration at point "b": 1.3 molt
Methane concentration at point "d": 3.4 molt
Recycle gas purging rate: 8 molt
The resul ts of measurements at the analytical points (" a"
to "f") in FIG. 2 under the steady state are described in Table
6.
[0110]
[Table 6]
10 Table 6
a b c d e f
H2/(kmol/hr) 0.00 1.14 5.12 3.98 0.35 0.00
C02/(kmol/hr) 0.36 0.34 1.07 0.73 0.07 0.00
COl (kmol/hr) 0.00 0.00 0.13 0.13 0.01 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.24 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.02 0.19 0.17 0.02 0.00
N2/(kmol/hr) 5.43 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 6.03 1. 52 6.56 5.04 0.45 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
[0111]
The methanol conversion based on C02 used was 72 molt,
and the methanol output per unit volume of the catalyst was
18 mol-methanol/L-Cat/hr.
15 [0112]
[REFERENCE EXAMPLE 1]
with the use of the system illustrated in FIG. 2, the
reaction was performed for 24 hours in the same manner as in
5
10
SF-2442
45
COMPARATIVE EXAMPLE 1 after a steady state was reached under
the following conditions.
[0113]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 hr-1
Catalyst packing scale: 16.6 L
Methane concentration at point "b": 1 mol%
Methane concentration at point "d": 18 mol%
Recycle gas purging rate: 1 mol%
The composition, the temperature and the pressure were
measured at the analytical points (" a" to "f") in FIG. 2 under
the steady state. The results are described in Table 7.
[0114]
!
15 [Table 7]
Table 7
a b c d e f
H2/(krnol/hr) 0.00 0.84 5.12 4.28 0.04 0.00
C02/(kmol/hr) 0.30 0.29 1. 07 0.78 0.01 0.00
CO/(kmol/hr) 0.00 0.00 0.14 0.14 0.00 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.20 0.02 0.03 0.01 0.00 0.29
Methane/(krnol/hr) 0.00 0.01 1.12 1.11 0.01 0.00
N2/(kmol/hr) 4.56 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 5.06 1.16 7.50 6.34 0.06 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
[0115]
The methanol conversion from C02 was 86 mol%, and the
5
10
15
SF-2442
46
methanol output per unit volume of the catalyst was 16
mol-methanol/L-Cat/hr.
[0116]
[COMPARATIVE EXAMPLE 4]
With the use of the system illustrated in FIG. 2, the
reaction was performed for 24 hours in the same manner as in
COMPARATIVE EXAMPLE 1 after a steady state was reached under
the following conditions.
[0117]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 h r "
Catalyst packing scale: 14.5 L
Methane concentration at point "b": 0.1 mol%
Methane concentration at point "d": 0.3 mol%
Recycle gas purging rate: 8 mol%
The results of measurements at the analytical points (" a"
to "f ") in FIG. 2 under the steady state are described in Table
8 •
20 [0118]
[Table 8]
Table 8
a b c d e f
H2/(kmol/hr) 0.00 1.14 5.12 3.98 0.35 0.00
C02/(kmol/hr) 0.36 0.34 1.07 0.73 0.07 0.00
CO/(kmol/hr) 0.00 0.00 0.13 0.13 0.01 0.00
SF-2442
47
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.24 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.001 0.014 0.013 0.001 0.00
N2/(kmol/hr) 5.43 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 6.03 1. 501 6.384 4.883 0.431 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
[0119]
The methanol conversion from C02 was 72 mol%, and the
methanol output per unit volume of the catalyst was 18
mol-methanol/L-Cat/hr.
5 [0120]
[REFERENCE EXAMPLE 2]
With the use of the system illustrated in FIG. 2, the
reaction was performed for 24 hours in the same manner as in
COMPARATIVE EXAMPLE 1 after a steady state was reached under
10 the following conditions.
[0121]
Reaction pressure: 5.0 MPa-G
Reaction temperature: 250°C
GHSV: 10000 h.r ?
II
'-II
15 Catalyst packing scale: 14.5 L
Methane concentration at point "b": 0.1 mol%
Methane concentration at point "d": 1.6 mol%
Recycle gas purging rate: 8 mo1%
The results of measurements at the analytical points (" a"
20 to" f") in FIG. 2 under the steady state are described in Table
SF-2442
48
9.
[0122]
[Table 9]
Table 9
a b c d e f
H2/(kmol/hr) 0.00 0.84 5.12 4.28 0.04 0.00
C02/(kmol/hr) 0.30 0.29 1. 07 0.78 0.01 0.00
CO/(kmol/hr) 0.00 0.00 0.14 0.14 0.00 0.00
Methanol/(kmol/hr) 0.00 0.00 0.02 0.02 0.00 0.26
Water/(kmol/hr) 0.20 0.02 0.03 0.01 0.00 0.29
Methane/(kmol/hr) 0.00 0.001 0.084 0.083 0.001 0.00
N2/(kmol/hr) 4.56 0.00 0.00 0.00 0.00 0.00
Total/(kmol/hr) 5.06 1.151 6.464 5.313 0.051 0.55
Temperature/oC 25 25 25 25 25 25
Pressure/MPa-G 0.00 0.76 5.00 4.60 0.10 0.00
5 [0123]
The methanol conversion from C02 was 86 mol%, and the
methanol output per unit volume of the catalyst was 18
mol-methanol/L-Cat/hr.
[0124]
I
10 The results in COMPARATIVE EXAMPLES and REFERENCE
EXAMPLES, as well as the results in EXAMPLES show that even
when the proportion of inert components is increased during
the production of methanol, the inventive process can realize
a methanol yield and a carbon dioxide conversion comparable
15 to when little inert components are present.

.. SF-2442
49
CLAIMS
[Claim 1]
A process for producing methanol, comprising:
a step (a) of reacting hydrogen and carbon dioxide with
5 each other in a reactor in the presence of a copper-containing
catalyst to produce a reaction mixture containing methanol;
a step (b) of circulating part or all of the reaction
mixture to the step (a);
a step (c1) of combusting part of the reaction mixture
10 to produce a combustion product and energy, and a step (c2)
of circulating part or all of the combustion product to the
step (a), the step (cl) and the step (c2) being performed when
the reaction mixture contains a compound (p) containing carbon
and hydrogen except methanol at not less than 0.1 mol% (wherein
15 all components of the reaction mixture excluding methanol and
water represent 100 mol%); and
a step (d) of separating a component including methanol
from the reaction mixture.
[Claim 2]
20 The process for producing methanol according to Claim 1,
wherein the compound (p) is inert to the copper-containing
catalyst.
[Claim 3]
The process for producing methanol according to Claim 1
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50
or 2, wherein at least part of the compounds (p) is a
hydrocarbon.
[Claim 4]
The process for producing methanol according to Claim 1
5 or 2, wherein at least part of the compounds (p) is methane.
[Claim 5]
The process for producing methanol according to Claim 1
or 2, wherein the compound (p) is methane.
[Claim 6]
10 The process for producing methanol according to anyone
of Claims 1 to 5, wherein the reaction mixture contains the
compound (p) at 0.1 to 50 mol%.
[Claim 7]
The process for producing methanol according to anyone
15 of Claims 1 to 6, wherein the copper-containing catalyst is
a catalyst containing copper, zinc, aluminum and silicon.
[Claim 8]
The process for producing methanol according to anyone
of Claims 1 to 7, wherein the energy produced in the step (c1)
20 is energy selected from thermal energy, electric energy and
kinetic energy.
[Claim 9]
The process for producing methanol according to anyone
of Claims 1 to 7, wherein the energy produced in the step (c1)
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is thermal energy.
Dated this 14/06/2013
t
"
51
~..3v~
NEHA SRIVASTAVA
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT