Low-temperature methanol synthesis in liquid-phase with a Raney Nickel- alkoxide system: Effect of Raney Nickel pretreatment and reaction conditions

Article abstract of DOI:10.1016/S1381-1169(98)00267-2

The CO hydrogenation in liquid-phase was carried out using a set catalyst composed of Raney-Ni and CH₃ONa in an autoclave of 234 ml under the reaction condition of 5 MPa, 423 K and 2 h. A high productivity (CO conversion of 92.4% with methanol selectivity of 99.8%) was achieved by eliminating the water after leaching of the Raney-Ni catalyst and by using CH₃ONa rather than CH₃CH₂ONa. Ni(CO)₄ was observed in the liquid-phase after the reaction under the condition of high CO content (CO/H₂ > 2). However, the formation of Ni(CO)₄ was not observed, when stoichiometric gas ratio (H₂/CO = 2) was used with Raney-Ni and CH₃ONa at 423 K, 5 MPa, and 2 h. Carbonylation of CH₃OH (CH₃ONa catalysis) seems to be faster than the carbonylation of Raney-Ni to Ni(CO)₄ under these conditions. Hydrogenolysis of methyl formate (MeF) on the Raney-Ni yielded both methanol and methane at 443 K. However, the by-product methane was never obtained when using Raney- Ni with CH₃ONa under the stoichiometric gas ratio (H₂/CO = 2) at 423 K, 5 MPa, and 2 h. The essential pathway must be the carbonylation of methanol to MeF with the CH₃ONa catalyst followed by the hydrogenolysis of MeF to methanol with the Raney-Ni; however, the synergy effect between Raney-Ni and CH₃ONa are suggested in the mechanism.

Full text of DOI:10.1016/S1381-1169(98)00267-2

Ž
.
Journal of Molecular Catalysis A: Chemical 141 1999 241–248
Low-temperature methanol synthesis in liquid-phase with a
Raney Nickel–alkoxide system: effect of Raney Nickel
pretreatment and reaction conditions
)
Eun Sook Lee, Ken-ichi Aika
Department of EnÕironmental Chemistry and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of
Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan
Abstract
The CO hydrogenation in liquid-phase was carried out using a set catalyst composed of Raney-Ni and CH3ONa in an
Ž
autoclave of 234 ml under the reaction condition of 5 MPa, 423 K and 2 h. A high productivity CO conversion of 92.4%
.
with methanol selectivity of 99.8% was achieved by eliminating the water after leaching of the Raney-Ni catalyst and by
Ž
.
using CH3ONa rather than CH3CH2ONa. Ni CO 4 was observed in the liquid-phase after the reaction under the condition of
Ž
.
Ž
.
high CO content COrH2)2 . However, the formation of Ni CO was not observed, when stoichiometric gas ratio
4
Ž
.
Ž
H2rCOs2 was used with Raney-Ni and CH3ONa at 423 K, 5 MPa, and 2 h. Carbonylation of CH3OH CH3ONa
.
Ž
.
catalysis seems to be faster than the carbonylation of Raney-Ni to Ni CO under these conditions. Hydrogenolysis of
4
Ž
.
methyl formate MeF on the Raney-Ni yielded both methanol and methane at 443 K. However, the by-product methane was
Ž
.
never obtained when using Raney-Ni with CH3ONa under the stoichiometric gas ratio H2rCOs2 at 423 K, 5 MPa, and 2
h. The essential pathway must be the carbonylation of methanol to MeF with the CH3ONa catalyst followed by the
hydrogenolysis of MeF to methanol with the Raney-Ni; however, the synergy effect between Raney-Ni and CH3ONa are
suggested in the mechanism. q 1999 Elsevier Science B.V. All rights reserved.
Keywords: Low-temperature methanol synthesis; Methanol synthesis in liquid-phase; Raney-Ni; CH3ONa
1. Introduction
Recently, a low-temperature 353–433 K, ini-
atures. If the heat of reaction is efficiently re-
moved, methanol production with high per-pass
conversion may be achieved. The catalyst pro-
posed by Brookhaven National Laboratory con-
Ž
.
tial pressure:1–5 MPa methanol synthesis pro-
Ž
.
Ž
.
cess from carbon monoxide CO and dihydro-
sists of NaH–RONa–M OAc in which Ms
2
w x
Ž
gen in the liquid phase has been claimed in
Ni, Pd or Co and Rstertiary amyl 1 for
example: CO conversion 86.9%, MeOH selec-
tivity 99.4% under the reaction condition of 5
MPa, 373 K, 1 h, H2rCOs2 in case of MsNi
2 . That is a well-known reagent which has
been used in hydrogenation reactions of halides,
ketones, alkenes and alkynes in the past studies
w
x
several patents 1–8 . Methanol synthesis from
CO and H2 is quite an exothermic and thermo-
dynamically favorable reaction at lower temper-
w x.
)
Corresponding author. Tel.: q81-45-924-5416; Fax: q81-45-
w
x
by Brunet and coworkers 9–12 . They have
924-5441; E-mail: kenika@chemenv.titech.ac.jp
1381-1169r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved.
Ž
.
PII: S1381-1169 98 00267-2

(
)
242
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
Table 1
Ž
.
reported that complex reducing agents CRA
Range of experimental operating conditions
Ž
.
such as NaH–RONa–M OAc are described as
2
Temperature
Total pressure
Reactant ratios H2 rCO
Stirrer speed
353–453 K
1–5 MPa
0.5–2
sources of new, atmospheric pressure, heteroge-
neous hydrogenation catalysts and M–H bond
formation is postulated as one of the key steps
in the catalytic hydrogenations. The active
Ž
.
1000 rpm
Ž
.
species of the system is believed to be Ni CO
4
Ž
.
and a complex base intermediate from NaH–
Ž
Raney-Ni was prepared by leaching Al 50
Ž
.
RONa–M OAc
in case of MsNi. Mar-
2
w x
.
Ž
.
Ž
wt.% and Ni 50 wt.% alloy from Kanto Pure
Chemical Industries in 50 ml of 5 N NaOH at
chionna et al. 8 have reported that nickel
.
1
Ž
w
Ž
. .
3xy
carbonyl anion HNi CO would be an
346–363 K over 2–38 h, then washed to give
pH 7, and finally dried with an evaporator. The
catalysts were added to triethylene glycol
active species for the methanol production, and
alkoxide would take part in the formation of the
Ž
.
anion. Thus, the Ni CO and alkoxide system
4
Ž
. Ž
.
dimethyl ether DME triglyme and subjected
to the reaction. The reaction was carried out in
batch operation in a magnetically stirred auto-
was studied and was found to show a high
w
x
activity 6–8 . But this system is difficult to be
Ž
.
used practically in industry because Ni CO is
4
Ž
.
clave Fig. 1 . The reactant gas composition
highly toxic, highly volatile and flammable.
In this work, it is our goal to develop a less
harmful and highly active catalyst instead of
Ž
.
Ž
ArrH2rCO is controlled by flow meters ml
1
miny for each gas, which was introduced into
the batch reactor autoclave at the room tempera-
ture, and pressurized to 5 MPa and maintained
.
Ž
.
Ni CO . Therefore, CO hydrogenation in liq-
4
uid-phase was carried out using a catalyst com-
posed of a Raney-Ni and CH3ONa as follows
Ž
.
for 2 h Table 1 .
The gas-phase and the liquid-phase compo-
nents were analyzed gas chromatographically
after the experiment. The produced amount of
methanol was calculated from the quantity of
Ž
Ž ..
Eq. 1 . It was studied how the activity was
influenced by the catalyst preparation and the
reaction conditions.
COq2H2
™
Raney-Ni alkoxide CH3OH
1
Ž .
solvent
2. Experimental
Catalysts were composed of Raney-Ni and
Ž
16.3% CH3ONa solution of methanol from
.
Wako Pure Chemical Industries, 99.5% . The
Fig. 2. Effect of washing methods on activity of Raney-Ni cata-
lyst. Reaction condition: 5 MPa, 423 K, 4 h. Ratio of reactant gas:
ArrH2 rCO s 20r160r80. Catalysts: Raney-Ni 17 mmol,
CH3CH2ONa 41 mmol, CH3CH2OH 210 mmol. Solvent: triglyme
Ž
.
Ž
88 ml. A and B Blank runs without further washing A stood
Ž .
.
Ž .
overnight before the reaction , C : washing with EtOH, D :
Ž .
washing with EtOH and drying in the vacuum, E : washing with
Ž .
EtOH and washing with THF, and drying in the evaporator, F :
Ž
.
washing with EtOH and drying in the evaporator, G : washing
with THF and drying in the evaporator.
Fig. 1. Diagram of the apparatus.

(
)
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
243
Table 2
Effect of alkoxides on methanol synthesis
Ž
.
Alkoxide MeOH
selectivity
Product yields mmol
MeOH MeFa DMEa CH4 EtFa
Ž .
%
MeONa
EtONa
82.7
82.7
67.3
29.5
0.1
–
6.9
2.7
0.1
0.3
–
0.2
Reaction condition: 5 MPa, 423 K, 4 h.
Ratio of reactant gas: ArrH2 rCOs20r160r80.
Catalysts: Raney-Ni 17 mmol, CH3CH2ONa or CH3ONa 41
mmol, CH3CH2OH or CH3OH 210 mmol.
Solvent: triglyme.
a MeF: methyl formate; DME: dimethylether; EtF: ethyl formate.
Fig. 3. The blank tests of methanol change without supplying
H2 rCO. Reaction condition: 5 MPa, 423 K, 4 h. Reactant gas: Ar
Ž
Ž
.
50 mlrmin . Catalysts: Raney-Ni 17 mmol, CH3ONa 16.3%
methanol before and after reaction. The quantity
of soluble nickel was measured with the induc-
.
CH3ONa 41 mmol, CH3OH 210 mmol . Solvent: triglyme.
Ž
.
tively coupled plasma method ICP: SPS 4000 .
The selectivity was determined on the carbon
Ž
.
basis. The apparent space time yield STY was
calculated from the product amount, the reac-
tion time during which a rapid pressure decrease
was observed, and the total volume of the cata-
3.2. Effect of alkoxide
The effect of alkoxide was investigated. The
Al–Ni alloy was leached with 50 ml of 5 N
NaOH for 30 min at 323 K, for 17 h at 346 K,
then washed with water to give pH 7, washed
with THF and finally dried with an evaporator.
Two kinds of alkoxides were compared as a
counter part of the Raney-Ni. The results are
shown in Table 2. Between the two alkoxides,
CH3ONa showed more effectiveness in the ac-
tivity than the CH3CH2ONa did although the
selectivites were similar.
Ž
.
lyst system 100 ml, including the solvent for
comparison with the other data.
3. Results
3.1. Effect of drying method on actiÕity of
Raney-Ni catalyst
After pretreatment of Raney-Ni, various dry-
ing methods were used to investigate the effect
of water elimination. Raney-Ni and CH3CH2-
ONa were used as catalysts to distinguish the
effects well. Because CH3CH2ONa is easily
decomposed by water, water should be removed
well before the reaction for the effective use of
the alkoxide. The Al–Ni alloy was leached with
50 ml of 5 N NaOH for 30 min at 323 K, for 15
h at 353 K and for 1 h at 363 K, then washed
with water to give pH 7, and finally washed
with various methods shown in Fig. 2. A higher
activity was achieved by eliminating water after
leaching of Raney-Ni catalyst. The most effec-
tive method to eliminate water in the Raney-Ni
Fig. 4. Effect of leaching time on activity of Raney-Ni catalyst.
Reaction condition: 5 MPa, 423 K, 4 h. Ratio of reactant gas:
ArrH2 rCO s 20r160r80. Catalysts: Raney-Ni 17 mmol,
CH3ONa 41 mmol, CH3OH 210 mmol. Solvent: triglyme 91.5
ml.
Ž
.
was the one using tetrahydrofuran THF rather
Ž
.
than ethanol Fig. 2 .

(
)
244
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
Table 3
Effect of reaction temperature on methanol synthesis
Ž
.
Reaction
temperature
MeOH
selectivity
CO concen-
Product yields mmol
STY of MeOH
Ž
y1
tration %
kg MeOH 1 hy1
Ž
.
.
MeOH
MeF
DME
CH4
Ž .
%
353 K
393 K
423 K
453 K
94.2
99.8
99.8
98.5
71.3
91.8
92.4
91.5
55.0
67.1
70.9
60.0
1.7
–
–
–
–
trace
0.1
trace
0.1
0.12
0.26
0.46
0.39
trace
trace
0.4
Reaction conditions: 5 MPa, 2 h, 353–453 K.
Ratio of reactant gas: ArrH2rCOs20r160r80.
Catalysts: Raney-Ni 17 mmol, CH3ONa 41 mmol, CH3OH 210 mmol.
Solvent: triglyme 91.5 ml.
3.3. Role of alkoxide, the blank test
3.4. Effect of leaching condition on actiÕity of
Raney-Ni catalyst
The higher activity was achieved by eliminat-
ing water after the pretreatment of Raney-Ni
catalyst in the early stage of this study. The
presence of small amount of water might react
with alkoxide to give methanol. For this reason,
we carried out two blank test runs using Raney-
We changed either the leaching time or the
Ž
.
Ž
.
temperature of Al 50% –Ni 50% alloy, and
the leached Raney-Ni was mixed with CH3ONa
and used for the reaction under the condition of
423 K, 5 MPa and 4 h. Leaching condition may
change the surface area and the content of resid-
ual Al of Raney-Ni. The product yield of
methanol was increased a little by increasing the
Ž
Ni and CH3ONa 30% CH3ONa 41 mmol:
.
CH3OH 210 mmol under the Ar gas only. The
quantity of methanol before and after the blank
run was analyzed by a gas chromatography.
This experiment was repeated twice and both of
them showed almost the same results. The quan-
tity of methanol after the reaction did not in-
crease as shown in Fig. 3. Therefore, CH3ONa
is not decomposed under the reaction condition
and is considered to play an active catalyst.
Ž
.
leaching time from 2 to 17 h Fig. 4 . But when
the leaching time was increased to 38 h, the
selectivity of methanol was decreased because
of an increase in the product yield of DME.
Also when the leaching temperature was in-
creased from 346 to 363 K. As a whole, when
Fig. 6. Effect of feed composition on product yields of methanol.
Reaction condition: 5 MPa, 423 K, 2 h. Ratio of reactant gas:
H2 rCOs2, 1, 0.5. Catalysts: Raney-Ni 1 g, CH3ONa 41 mmol,
CH3OH 210 mmol. Solvent: triglyme 91.5 ml.
Fig. 5. Time courses of reaction temperature and pressure during
methanol synthesis.

(
)
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
245
Table 4
The blank tests of catalyst activity by introducing only H2 or CO
Ž .
Product yields mmol
Ratios of
reactant gas
Reaction
Charge of
CO
CO concen-
MeOH
selectivity
Ž
.
condition
tration %
MeOH
MeF
DME
CH4
y1
ArrH2rCO
KMPa hy1
mmol
Ž
.
Ž
.
Ž
.
Ž
.
%
20r160r0
20r160r80
20r0r80
423r5r2
423r5r2
423r5r2
–
84.9
222.3
–
92.4
67.0
–
95.2
–
–
70.9
–
–
trace
14.0
–
1.8
8.7
0.50
trace
0.02
Catalysts: Raney-Ni 17 mmol, CH3ONa 41 mmol, CH3OH 210 mmol.
Solvent: triglyme 91.5 ml.
changing leaching condition of Raney-Ni cata-
lyst as above, no great difference in the activity
of the catalyst was found.
3.6. Effect of reactant gas ratio
The experiments were carried out using
Raney-Ni and CH3ONa with the reaction condi-
tion of 423 K, 5 MPa and 2 h, while only the
ratio of reactant gas was changed. The product
yield of methanol was increased by increasing
3.5. Effect of reaction temperature
The effect of the reaction temperature on the
catalyst activity was investigated. The results
are shown in Table 3. The experiment was
carried out using Raney-Ni and CH3ONa from
353 K to 453 K. The selectivity of methanol
obtained was over 95% at 423 K. When the
Ž
.
the ratio of reactant gas H2rCOs0.5–2 , but
Ž
.
DME and methyl formate MeF were de-
creased as shown in Fig. 6. The negative values
of methanol production at H2rCOs0.5 means
that methanol solvent is converted to DME and
MeF.
Ž
.
reactant gas H2rCOs2 was introduced into
the reactor at the room temperature and raised
to 423 K, the pressure immediately decreased
after this reaction temperature was attained. An
example of the time course of the temperature
and pressure during the reaction are shown in
Fig. 5. The slope of the initial pressure drop was
3.7. Carbonylation of methanol
Ž
.
4
Generally, it is known that Ni CO could be
formed from CO gas and Ni. Ni CO is hard to
be handled because it is highly toxic, highly
volatile and flammable. According to the patents
Ž
.
4
Ž
.
w
x
taken to calculate the reaction rate STY .
5–7 , CO conversion of more than 90% and
Table 5
The ICP analysis of soluble Ni
Ž
.
Code
number
Reaction conditions
Tempera- Pressure
Ratio of reactant
Catalysts
Quantity of Ni mg
Ž
.
gas ArrH2rCO
Time
Before reaction
After reaction
Ž
.
Ž
.
Ž .
h
Ž
.
Ž
.
ture K
MPa
Raney metal
in the liquid
1
2
3
4
5
6
7
8
423
423
423
423
423
423
423
423
5
5
5
5
5
5
5
5
4
2
4
2
2
2
2
4
20r0r0
R-Ni, CH3ONa
R-Ni, CH3ONa
R-Ni, CH3ONa
R-Ni, CH3ONa
R-Ni, CH3ONa
R-Ni, CH3ONa
R-Ni
1000
1000
1000
1000
1000
1000
1000
1000
0.03
0.07
0.03
0.08
24.45
64.16
20r160r0
20r160r80
20r160r80
20r40r80
20r0r80
20r160r80
20r160r80
489.91
0.20
R-Ni, CH3CH2ONa

(
)
246
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
Table 6
The hydrogenolysis of methyl formate
Ž .
Product yields mmol
Code
number
RRGa
Catalyst
Reagent
Solvent
RCb
Ž
MeOH
selectivity
y1
ArrH2
Raney-Ni
MeF
triglyme
K MPa hy1
Ž
.
Ž
.
Ž
.
Ž
.
.
MeOH
CH4
C2 H6
CO
Ž .
%
1
2
3
4
20r160
20r160
20r160
20r160
1 g
1 g
2 g
3 g
13 ml
13 ml
13 ml
13 ml
87 ml
87 ml
87 ml
87 ml
423r5r2
443r5r2
423r5r15
443r5r15
21.0
62.5
54.0
47.0
4.8
11.1
28.9
18.0
6.5
24.1
155.9
0.02
0.08
0.25
5.30
0.5
0.2
0.4
0.1
149.1
aRatio of reactant gas.
bReaction conditions.
Ž .
presence of H2 code no. 7 . This means that
methanol selectivity of more than 95% were
Ž
.
Ž
.
alkoxide prevents the formation of Ni CO
4
obtained when a catalyst composed of Ni CO
4
Ž
.
and alkoxide was applied in the liquid-phase. In
this study, we also obtained CO conversion of
more than 90% and methanol selectivity more
than 95% by using Raney-Ni and alkoxide un-
der the reaction condition of 423 K, 5 MPa, and
code no. 4, 8 .
3.9. Hydrogenolysis of MeF
Alkoxide is known to be an quite effective
catalyst of methanol carbonylation to form MeF.
Then the second step must be the formation of
methanol through hydrogenolysis of MeF. The
question is whether Raney-Ni catalyzes this pro-
cess independently or is accelerated by alkox-
ide. Hydrogenation experiment of MeF was car-
ried out using Raney-Ni under the H2 gas only.
The results are shown in Table 6. Increasing the
reaction time and the quantity of Raney-Ni, a
higher product yields of methanol and methane
Ž
.
2 h with the reactant gas H2rCOs2 . Here, a
Ž
.
question arises whether Ni CO is formed from
4
Raney-Ni and CO gas during the reaction condi-
tion or not. The blank experiments were carried
out by introducing only H2 or CO and the
results are shown in Table 4. H2 gave almost no
product, while CO alone was consumed much
more than that with H2. The CO consumption
Ž
.
suggests the formation of MeF and Ni CO .
4
Ž
3.8. ICP analysis
were obtained code no. 1–3, at 423 K, code no.
.
24 at 443 K .
Ž
.
If Ni CO is formed, the solvent must con-
4
tain Ni, which can be analyzed by the ICP
method. The soluble Ni in the solvent after the
reaction are shown in Table 5. The reactant gas
4. Discussion
Ž
.
ratio H2rCO and the catalyst composition
4.1. Role of alkoxide
Ž
.
were changed Table 6 , and several new find-
ings were obtained.
1. Under the standard reaction condition, no
Water and carbon dioxide have been reported
to have negative effects on the carbonylation
Ž
.
Ž
.
w x
w x
Ni CO is formed code no. 3 and 4 .
catalyst by Tonner et al. 13 , Liu et al. 14 ,
4
Ž
.
Ž
.
w x
w x
2. A part of Ni 6.4% is turned to Ni CO if
Maatschappij 15 , Imyanitov et al. 16 and
4
Ž
.
w x
no H2 is present code no. 6 and H2 re-
tarded the Ni CO formation code no. 5,
4 .
UCB 17 , because they react with the alkali
metal methoxides to form inactive products al-
kali formates, alkali methyl carbonates, or alkali
hydroxide . In this study, Raney-Ni and alkox-
Ž
.
Ž
Ž
4
.
.
3. But, if alkoxide is not applied a half of Ni
Ž
.
Ž
.
49% was turned to Ni CO even in the
ide were used as a set catalyst. Alkoxide can be
4

(
)
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
247
turned to hydroxide-forming methanol by water
existing in the catalyst, solvent, or reactant gas.
Therefore, after leaching the Raney-Ni, various
drying methods were used to investigate the
effect of eliminating water at the first part of
CH3OK as the usual homogeneous formate syn-
thesis catalyst and a heterogeneous catalyst of
copper–chromite under the mild conditions of
w
x
413–453 K and 38–65 bar by Liu et al. 22 .
Palekar et al. proposed an overall reaction model
in which MeF is formed by homogeneous car-
Ž
.
this study Fig. 2 . Among them, the most effec-
tive method was the washing with THF, be-
cause the boiling point of THF is lower than
ethanol. Another blank experiment was carried
out to investigate the effect of water as shown
in Fig. 3. According to the result, the quantity
Ž
Ž ..
bonylation Eq. 2 near the copper–chromite
surface and in the bulk methoxide liquid, cou-
pled with regeneration of the methoxide catalyst
Ž
Ž ..
Eq. 3 on the copper–chromite surface. This
is followed by heterogeneous hydrogenolysis of
Ž
.
Ž
Ž .. w x
of solvent methanol 210 mmol increased only
a little by mixing with Raney-Ni at the begin-
ning of the reaction; however, the quantity of
MeF to yield methanol Eq. 4 23 , a part of
which had been proposed by Sorum and On-
w
x
Ž .
sager 21 , as shown in Eq. 4 .
Ž
.
methanol 226 mmol was not increased during
the blank test period without H2rCO. There-
fore, alkoxide is considered to be unchanged
during the reaction and to play a role as a
catalyst. The formation of MeF in the carbony-
lation reaction is known to occur through the
two-step mechanism: the addition of CO to the
2H
HCOOCH ™CH OCO a ™ CH OCHOH a
Ž .
Ž .
3
3
3
3H
™CH O a qHCOH a ™ 2CH OH
4
Ž .
Ž .
Ž .
3
3
Ž
.
In this study, we found that Ni CO forma-
4
tion from CO and Raney-Ni was prevented by
another catalyst component, alkoxide, under the
synthesis condition. For this reason, we can
propose that Raney-Ni acts as a solid catalyst
like the copper–chromite and does not act as an
homogeneous molecular catalyst, Ni CO . The
main role of alkoxide must be the carbonylation
to form MeF as the first step Eq. 5 . The
main role of Raney-Ni surface must be the
hydrogenolysis of MeF to form methanol Eq.
6 . However, the second step is not simple. If
MeF is treated with H2 on Raney-Ni, a side
reaction, methanation, occurs Table 6 . The
side reaction is prevented by the presence of CO
and alkoxide.
Ž
Ž ..
methoxide anion Eq. 2 and the reaction with
Ž
Ž .. w x
the proton Eq. 3 18 .
CH3OyqCO™CH3OCOy
CH3OCOyqCH3OH™HCOOCH3 qCH3Oy
2
Ž .
Ž
.
4
3
Ž .
Ž
Ž ..
y
Ž
.
can react as a nucle-
Alkoxide ion RO
Ž
ophile in a substitution reaction or as a base in
an elimination. As the size of the R group is
increased, the reactivity decreases. Methoxide
ion is a stronger base and a better nucleophile
than ethoxide ion. Therefore, in this study, a
higher activity was obtained by using CH3ONa
rather than CH3CH2ONa as is shown in Table
2.
Ž ..
Ž
.
CH 3Oy
CH3OHqCO ™ HCOOCH3
5
Ž .
Raney-Ni
HCOOCH3 q2H2 ™ 2CH3OH
6
Ž .
4.2. Role of Raney-Ni
Hydrogenolysis of MeF has been studied in
w
x
the gas phase 19 and in the slurry phase
5. Conclusions
w
x
13,20,21 at the temperature of 393 to 473 K
using copper–chromite catalysts. The concur-
rent synthesis of methanol has been studied in a
single mechanically agitated slurry reactor using
By using a catalyst composed of Raney-Ni
and CH3ONa, we obtained the CO conversion

(
)
248
E.S. Lee, K.-i. AikarJournal of Molecular Catalysis A: Chemical 141 1999 241–248
of over 90% and the methanol selectivity of
over 95% at 423 K, 5 MPa, 2 h, with the
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stoichiometric reactant gas H2rCOs2 . The
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decomposed during the reaction, because
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blank run. When using the catalyst of Raney-Ni
and CH3ONa under the reaction condition of
w x
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.
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