Note: Descriptions are shown in the official language in which they were submitted.
~1740`31
sac~;ground of the Invention
This invention relates to a process for the catalytic conver-
sion of methanol into hydrogen and carbon monoxide.
There are increasing demands for hydrogen and carbon monoxide
in many fields and methanol is now an important starting material
therefor in that it can give hydrogen and carbon monoxide through
catalytic decomposition. In an internal combustion engine, the
waste heat generated therefrom can be utilized for the catalytic
conversion of methanol into hydrogen and carbon monoxide, the
mixed gas product being introduced into the engine as at least a
part of the fuel. This method is advantages not only from an
economic point of view but also from the standpoint of preventive
pollution since the discharge of nitrogen oxides and carbon monoxid
l may be significantly reduced.
Catalytic conversion of methanol is also utili2ed in a fuel
icell, in which an oxygen-containing gas is supplied to the anode
and a fuel, ?referably hydrogen,is supplied to the cathode. The
reaction between the anode and cathode can produce an electrical
energy. The hydrogen may be produced by methanol. Thus, methanol
is catalytically converted into hydrogen and carbon monoxide, the
latter being further reacted with water to yield hydrogen and
carbon dioxide by water gas reaction. The hydrogen obtained in the
two-stage process is separated from carbon dioxide for the intro-
duction to the cathode.
In addition, hydrogen and carbon monoxide are used in a wide
variety of chemical plants. For example, hydrogen is utilized for
hydrogenation of organic compounds, hydrotreatment of heavy
hydrocarbon oils, etc.and carbon monoxide is utilized for the
production of carbonyl group-containing organic compounds.
~17403~
There is, therefore, a great demand for an effec-
tive process capable of converting methanol into hydrogen
and carbon monoxide. A process is proposed in which a
catalyst containing nickel, l~mthanum and ruthenium
supported on silica gel is used. Although the catalyst
can exhibit a relatively high activity for the decomposi~
tion of methanol at an initial stage r the catalytic
activity is gradually lowered as the reaction at about 300
C proceeds and the catalyst is considerably deteriorated
after about several hours. A process is also known
wherein a catalyst having copper and~or nickel supported
on silica gel is used. This catalyst, however, is poor
in resistance to heat and7 moreover~ is defective because
with its undesirable by-products such as water and methane
are formed at about 400C or more. The term "for`mation
of ''~y-productsll herein and hereinafter means the case where
compounds other th m methanol, hydrogen and carbon monoxide
are contained in the reaction product in an amount of 10 ~-
vol % or more. The formation of by~products requires an
,
additional step for the removal thereof and is not accept-
able in practice.
gummary of tXe Invention
It is, therefore, an object of an aspect of the
present invention to provide a process which is devoid of
the drawbacks of the prior art process.
An object of an aspect of the present invention is
to provide an effective process by which methanol may be
3-
1174~31
decomposed into hydrogen and carbon monoxide while mini-
mizing the formation of undesirable by-products such as
dimethyl ether, methane, water, carbon dioxide and methyl
formaldehyde.
An object of an aspect of the present invention is
to provide a process in which the catalytic conversion of
methanol can be performed in a stable manner for a long
period of process time.
In accomplishing the foregoing objects, there is
provided in accordance with the present invention a process
of decomposing methanol for the production of hydrogen and
carbon monoxide, which comprises contacting a gas stream
containing methanol with a catalyst including a carrier
material of alumina, and nickel and potassium supported
on the carrier material. The content of Ni is in the
range of about 1-12 mg-atom per one gram of the carrier
and the content of K is n the range of about 1-12 mg-atom
per one gram of the carrier.
Other objectsJ features and advantages of the
present invention will become apparent from the detailed
description of the invention to follow.
Detailed Description of the Invention
The process of this invention includes contacting
a methanol-containing gas with a catalyst comprised of
alumina as a carrier material and nickel and potassium
carried on the carrier material.
Any activated alumina may be suitably ~sed as the
carrier material. Illustrative of such activated alumina
A -4-
~L174~31
-4a- .
are y (gamma)-alumina, ~ ~kappa)-alumina, ~ (delta)-alumina,
~eta)-alumina, B ltheata)-alumina, p (rho)-alumina and
lchai)-alumina. The alumina carrier preferably has a
specific surface area of about 150 - 300 m2/g.
Supported on the alumina carrier are nickel and po-
tassium. The content of the nickel in the catalyst should
fall within the
~? '',
1~74C13~
~range of about 1-12 mg-atom (i.e. 58.7 - 704.4 mg) per 1 g of the
¦alumina carrier. An amount of Ni below 1 mg-atom is insufficient
¦to impart practically acceptable activity to the catalyst and,
I moreover, causes a danger of the formation of by-products. Above
¦ 12 mg-atom Ni, the catalytlc activity is considerably lowered.
The Ni content is preferably about 2 - 8 mg-atom. The content of
¦ the potassium in the catalyst should also fall within the range of
about 1-12 mg-atom li.e. 39.1 - 469.2 mg) per 1 g of the alumina
l carrier. An amount of K below 1 mg-atom causes the formation of
¦ by-products. Above 12 mg-atom K, the catalyst becomes poor in
activity. The K content is preferably about 2-8 mg-atom~
The catalyst of this invention may be prepared in any known
¦manner. For example, a water soluble nickel salt such as nickel
¦nitrate is dissolved in water, with which an alumina carrier
lS Imaterial is impregnated. The impregnated material is then dried
¦and calcined in tne atmosphere of oxygen. The calcination is
¦preferably conducted while elevating the tem~erature stepwise from
¦100 to 500C. The carrier material thus loaded with nickel is
~then impregnated with a solution containing a potassium compound
such as potassium nitrate. ~he resulting impregnated material is
¦subsequently dried and calcined in the same manner as described
¦above to obtain a catalyst containing nickel and potassium carried
on the carrier material. The catalyst may also be prepared by
impregnating a carrier material with a solution containing both
nickel and potassium compounds, followed by drying and calcination.
In order to stabilize the catalytic performance, it is
preferred that the thus obtained catalyst be subjected to a pre-
treatment with a reducing gas. The pretreatment, which may be .
performed either just after the calcinatiOn step or before conduct-
ing the methanol conversion process, includes heating the catalyst
~1~4C13~
at a temperature of 200 - 500C, preferably 300 - 400C, for 1 - 15
hours in the atmosphere of a reducing gas such as hydrogen or
methanol.
The step of contacting a methanol-containing gas stream with
S the catal~st is carried out at a temperature of 200 - 600C,
preferably 250 - 500C for 0.1 - 12 sec, preferably 1 - 10 sec.
The content of the methanol in the gas stream can be 100 ~. The
gas stream may contain an inert gas such as argon or nitrogen,
however.
The following examples will further illustrate the present
invention.
Example 1
Nickel nitrate was dissolved in water to obtain an aqueous
solution having a Ni content of 1 g/Q. ~ith the solution was
impregnated a y-alumina carrier to obtain nickel-impregnated
alumina. The impregnated alumina was dried and calcined at 500C
for 4 hours whereby to obtain a nickel-carrying alumina having a
Ni content of 2 mg-atom per one gram of the alumina carrier. The
nickel-carrying alumina was then impregnated with an aqueous
solution containing potassium nitrate and having a K content of
1 g/Q to obtain an impregnated material. The impregnated material
was then dried and calcined in the same manner as above thereby to
obtain a nickel and potassium-carrying alumina catalyst having a
Ni content of 2 mg-atom and a K content of 2 mg-atom per 1 g of
the carrier.
0.5 g of the thus obtained catalyst were packed in a reac~ion
tube having an inner diameter of 9 mm, through which was streamed
first a hydrogen gas at 500C for 2 hours and then a mixed gas
containing methanol vapor (partlal pressure: 0.8 atm.) and argon
. .
1~74C~31
(partial pressure: 0.2 atm.) at a flow rate of 12.4 mQ/hour in
ter~s of liquid methanol at 300 - 350C for 15 hours to stabilize
the catalyst performance- After this pretreatment, a feed gas
con~aining methanol vapor (0.5 atm.) and argon ~0.5 atm.) was
introduced into the reaction tube for contact with the packed
catalyst layer at 350C for 12 sec. The effluent gas was sampled
for analyzing the conversion ~decomposition~ rate and the composi-
tion thereof. The results of the analysis are shown in Table 1.
Comparative Example 1
Thirteen types of catalysts were prepared using nitrates of
the metal components shown in Table 1 in the same manner as that
in Example 1. The content of each of the catalyst metal components
was 2 mg-atom per one gram of the alumina carrier. However,
rhodium was contained in an amount of 0.05 mg-atom per one gram of
the alumina carrier ~Experiment No. 14~ and no catalyst metal
component was contained in the catalyst of Experiment No. 2. Each
catalyst was subjected to pretreatment conditions in the same
manner as that in Example 1 and, with the use of the pretreated
catalyst, methanol was decomposed in the same manner as that in
Example 1. The results were as shown in Table 1.
~74~P3i
_ h .~
~ ~
_ ._ ,
_ S o o O O O o o o o o
~1 Ll .. _ _ .__
U ~
~ ~ o ~ I~ ~ o o o o o o
~0 S Il~
o a
o _
8~ E u~ o ~ o o o ~ o o
aJ t~ Q
Q ~)
O In O ~ o o 1` o o r~
_
d~ . U~ .
u~ O ~`I N ~n o N ~ u~ n o
~S~ u~
r~ E .,~
Z
` 0~
~ ~ ~i ~1 Z ~ O ~ ~ O :~ ~ s
~, ~ 8 z E~
E
~ o ~ o ~ ~ ~ er .
XZ ___ _ _
~ 8 -
~74Q31
As will be appreciated from the results shown in Table 1,
whilst a high methanol conversion is attained when alumina is used
by itself as catalyst (Experiment No. 23, the majority of the
product is dimethyl ether and water and neither hydrogen nor
carbon monoxide is yielded. With a catalyst containing potassium
alone as catalyst metal component (Experiment No. 3), methanol
conversion is significantly lowered and no improvement in selecti-
vity is seen as compared with the case of Experiment No. 2. With
a catalyst containin$ nickel alone as catalyst metal component
(Experiment No~ 4), on the other hand, undesirable by-products are
formed in large amounts. In contrast, the catalyst of the present
¦invention containing both nickel and potassium (Experiment No. 1)
¦exhibits both a high methanol conversion and an excellent selecti-
¦vity to hydrogen and carbon monoxide. When the nickel is substi-
¦tuted with other metals ~Experiments Nos. 5-14), satisfactory
¦con~ersion is not obtained.
Example 2
Methanol decomposition was conducted in the same manner as
that in Example 1 except that the pretreatment conditions were
varied. Thus, in Experiments Nos. 15 and 16, argon and hydrogen
were used, respectively, in place of the hydrogen used in the
pretreatment step of Example 1. In Experiment No. 17, the pre-
treatment was carried out by feeding a hydrogen gas to the reaction
tube at 310 - 350C for 15 hours. In Experiment No. 18, the
pretreatment was performed by feeding the same mixed gas as used
in Example 1 at 300 - 350C for 15 hours. The results are shown
in Table 2 together with those of Experiment No. 1.
~7~ 31
Table 2
I . .
Experiment Treatment Conversion Composition of product ~vol %)
of methanol
No. gas (%) Hydrogen monoxide By-products
. . . ..
1 hydrogen, 52 65 35 0
methanol 79 67 33 0
16 oxygen, 55 67 33 0
17 hydrogen 61 64.5 35.5 0
18 methanol 75 68 32 0
_ .. _ . .
The results in Table 2 indicate that pretreatment conditions
have an influence upon the activity of the catalyst. It is seen
¦that when the treatment with methano~l is to be preceded by the
high temperature treatment with other gases (Experiment Nos. 1, 15
and 16), the use of argon is preferable.
¦Example 3 .
A catalyst having a Ni content of 4 mg-atom and a-K content
of 4 mg-atom per one gram of alumina was prepared in the same
manner as described in Example 1. With the use of this catalyst,
methanol was decomposed in the same manner as that in Example 1
except that argon was used in place of hydrogen in the pretreatment
step and the catalytic conversion was performed at temperatures of
3~0C (Experiment No. 19) and 430~C ~Experiment No. 20). The
results are shown in Table 3.
` ~' 10 -
1~7~CD3~
Comparative Example 2
Using silica gel as a carrier material, two types of catalysts
were prepared in the same manner as that in Example 1. One of the
catalysts contained nickel as its catalytic metal component in an
amount of 4 mg-atom per one gram of the silica gel carrier~ The
other cataly t contained nickel and potassium each in an amount of
4 mg-atom per one gram of the carrier. With the use of these
catalysts, methanol was decomposed in the same manner as that in
Exam~le 3. The results are summarized in Table 3.
~ 403;~
~ ~ o o o o o o
I .~ __
o~ ~
l _I Q X O ~ O O N
I ~ ~ _
l 3 O O _ O N
l ~0 C~ __
l O S o ~n N O U~
I . ,0 ~)
l .~ O X 1~ N 1~ o O u~
I ~ ~ao ~ ~1 ~_1
l C~ ~ ,
l O u~ ~ N un O ~D
l ~ ~ ~ ~D~ I~ ~r
Q r--I e
E~ U) O^
~ dP ~ O O O N O
O ~- U~ _~ t` ~ _l
O ~ .~
~3
o ~ o o o o o o
.,, ~ ~, o ~ o ~ o
~o ~. ~ .,. ~ ~ ~
. ,~ ~ 0
.~ .~ ~ ~ ~ ~
U 0-
~o ~ .~ ~;
~ ~ ~ .,, Z .,,
o æ æ .
E ._
,1 0 O~ O _1 ~ ~ ~
X _I N N N N N
, ~ ~
~ - 12 -
1 117~031
l As will be seen from Table 3, the nickel-carrying silica gel
¦ca~alyst exhibits outstanding activity at 300C (Experiment No. 21)
¦With this catalyst, however, when ~he reaction temperature is
¦raised so as to increase the conversion, the selectivity to hydro-
¦gen and carbon monoxide becomes considerably lowered and the
¦yield o~ by-products increases (Experiment No. 22). This tendency
¦is also observed in the case of the catalyst having both nickel
and potassium carried on silica gel ~Experiments Nos. 23 and 24).
I In contrast thereto~ the catalyst of this invention can exhibit
l good catalytic activity even at a low temperature (Experiment No.
19) and excellent selectivity to hydrogen and carbon monoxide even
at a high temperature ~Experiment No. 20).
Example 4
l Catalysts having the various Ni and K contents indicated in
1 Table 4 were prepared in the same manner as that in Example 1.
Tests of catalytic conversion of methanol were carried out with
the,e catalysts in the same manner as described in Example 1 at
temperatures of 300, 350, 400 and 450C. The test results were as
shown in Table 4.
- 13
!
.. ..
~17~31
Table 4
Content of catalytic Conversion of methanol(~)
Experiment metal component
No. (mg-atom/g-alumlna¦ Reacti )n temperatur~ (C)
. Ni K 300 350 400 450
0 2 2 9 24
26 1 2 29 75 95
27 2 2 34 79 98
28 4 0 58 83 93 98
29 4 0.5 24 50 74 99
4 1 28 67 98 100
31 4 2 51 91 100 100
32 4 3 51 89 99 100
33 4 4 53 89 98 100
34 4 5 40 79 96 96
4 6 42 81 96 99
36 4 8 44 81 96 97
37 4 12 33 71 94 99
38 6 2 60 91 100 100
39 8 2 51 87 100 100
8 8 44 78 93 97
41 12 4 45 85 100 100
I . . .. _ _ .... .
¦ It will be appreciated from the results in Table 4 that the
¦catalyst containing potassium alone (Experiment No. 25) fails to .
¦show practically acceptable methanol conversion activity at any
¦temperatures. Moreover, as shown in Table 1, Experiment No. 3,
considerably large amounts of by-products are produced. While the
catalyst having nickel alone ~Experiment No. 28) can show high
,, . . -,
1174CD31
me~anol decomposition activity, the yield of by-products is very
hig~ as shown in Table 1~ Experiment No. 4- This is al50 the case
wit5 the catalyst having a K content of 0.5 mg-atom (Experiment No.
29l. The other catalysts shown in Table 4 can exhibit practically
ac~ptable methanol deco~position activity at suitably selected
tem~eratures and can show good selectivity to hydrogen and carbon
monoxide. Especially, the catalysts having 2-8 mg-atom each, of
Ni and K contents are very advantageous because they can exhibit
satisfactory ætivity at a temperature of 350C while substantially
preventing the formation of by-products (Experiments Nos. 27, 31-36
and 38-40).
ExaDple 5
The same type of the catalyst as employed in Example 4,
Experiment No. 33, was used in this example. The catalyst was
subjected to the same pretreatment conditions as those in Example
4 except that the treatment with the mixed gas was continued furthe r
145 hours, i.e. 160 hours in total. Thereafter, a methanol
dec~mposition test was performed in the same manner as that in
IExa~ple 1 at temperatures of 300, 350 and 400C. The results are
Ishown in Table 5 together with those of Experiment No. 33.
¦ Table 5
I ..... .
I . . . ~ .
I . Conversion of methanol~%3
I Experiment Pretreatment tlme _ _
No. (with methanoll 300C 350C 400C
33 15 hours 53 89 98
42 160 hours 50 a4 99
~ 15 -
1 1174(~31
The results in Table 5 show that the catalyst used for 160
hours can still exhibit excellent catalytic performance comparable
to the catalyst after 15 hours process time. The analysis of the
product revealed that the product consisted of 65 ~ of hydrogen
S and 35 ~ of carbon monoxide. These facts indicate that the
catalyst of this invention has a sufficiently long catalyst life.
~ 16 ~
