Relative roles of methanol synthesis and solid acid catalysts in the direct DME synthesis from syngas

Article abstract of DOI:10.1002/bkcs.10235

The Cu/ZnO/Al₂O₃ catalysts with 13.0 and 30.6 m²Cu/g were designated as HM (highly active catalysts for methanol synthesis) and LM (low active catalysts for methanol synthesis), respectively. γ-Al₂O₃ and η-Al₂O₃ were designated as LD (low active catalysts for methanol dehydration) and HD (highly active catalysts for methanol dehydration), respectively. Four catalytic systems (LMLD, LMHD, HMLD, and HMHD) were prepared by admixing methanol synthesis catalysts and methanol dehydration catalysts. The syngas to dimethyl ether (DME) (STD) reaction was conducted at a GHSV of 6000 mL/g_cat/h, 42 atm, and 250 °C. The activity of LMLD was almost same as that of LMDH, indicating that the activity of solid acid catalysts did not influence the STD reaction on the admixed catalysts using LM. On the other hand, the activity of HMHD was much higher than that of HMLD, indicating that the solid acid catalysts controlled the STD reaction on the admixed catalysts using HM.

Full text of DOI:10.1002/bkcs.10235

Article
DOI: 10.1002/bkcs.10235
BULLETIN OF THE
H. Jung et al.
KOREAN CHEMICAL SOCIETY
RelativeRolesofMethanolSynthesisandSolidAcidCatalystsintheDirect
DME Synthesis from Syngas
†,‡
‡
†
‡,*
Heon Jung, Seong-Min Lee, Dae-Ryook Yang, and Kwang-Deog Jung
†
Department of Chemical & Biological Engineering, Korea University, Seoul 136-701, Korea
Clean Energy Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791, Korea.
E-mail: jkdcat@kist.re.kr
‡
*
Received September 22, 2014, Accepted December 29, 2014, Published online March 25, 2015
2
The Cu/ZnO/Al O catalysts with 13.0 and 30.6 m Cu/g were designated as HM (highly active catalysts for
2
3
methanol synthesis) and LM (low active catalysts for methanol synthesis), respectively. γ-Al O and η-Al O
2
3
2 3
were designated as LD (low active catalysts for methanol dehydration) and HD (highly active catalysts for
methanol dehydration), respectively. Four catalytic systems (LMLD, LMHD, HMLD, and HMHD) were pre-
pared by admixing methanol synthesis catalysts and methanol dehydration catalysts. The syngas to dimethyl
ꢀ
ether (DME) (STD) reaction was conducted at a GHSV of 6000 mL/g /h, 42 atm, and 250 C. The activity of
cat
LMLD was almost same as that of LMDH, indicating that the activity of solid acid catalysts did not influence
the STD reaction on the admixed catalysts using LM. On the other hand, the activity of HMHD was much
higher than that of HMLD, indicating that the solid acid catalysts controlled the STD reaction on the admixed
catalysts using HM.
Keywords: Direct DME synthesis, Methanol synthesis, Methanol dehydration, Effects of Cu surface area
Introduction
The overall reaction (4a) or (4b) can be derived from reac-
tions (1) depending on the H /CO mole ratio.
2
Dimethyl ether (DME) has physical properties similar to those
of liquefied petroleum gas (LPG). In addition to the physical
characters, DME has been known to be an environmentally
2CO + 4H2 $ CH3OCH3 + H2O
CO + 3H2 $ CH3OCH3 + CO2
ð4aÞ
ð4bÞ
3
1
,2
clean fuel due to its low soot, NOx, and SOx emission. From
that point, DME has been considered as a substitute fuel for
diesel and LPG. Because LPG fueling infrastructures were
established in Asia region, attempts have been made to use
DME as a car fuel mainly in Asia. Recently, some truck com-
panies such as Volvo and Mack have announced the supply
of DME trucks by 2015, indicating that technical issues
of the DME car are almost solved. The International DME
association (IDA) has reported that the heavy-duty DME-
fueled vehicles have completed 100 000 km (IDA fact sheet
Steam reforming or autothermal reforming of methane
gives R ratios ((H -CO )/(CO + CO )) higher than 2.0. There-
2
2
2
fore, methanol can be coproduced with DME if the H /CO
2
ratio is much higher than 2.0 in direct DME synthesis.
Therefore, Haldor and Topsoe claimed coproduction of
methanol and DME in the direct DME synthesis from methane
reforming (R = 3.0). On the other hand, the molar ratio of
H /CO of syngas from coal gasification or biogasification
2
was close to 1.0. In that case, it is clear that the direct DME
synthesis can have an advantage over a two-step DME proc-
ess, because a shift reactor is required for the two-step DME
synthesis from coal gasification or biogasification to adjust
3
No. 2).
DME has been commercially produced in two steps: (1)
methanol synthesis from syngas, and (2) DME synthesis by
methanol dehydration. It was reported that it is more advanta-
the molar ratio of H /CO to 2.0 in the first step (methanol
4–7
2
geous to synthesize DME from syngas in one step. Syngas
to DME (STD) conversion is mainly composed of three con-
secutive reactions on the mixed catalysts Cu/ZnO/Al O and
synthesis).
As discussed, the STD reaction requires two functionalities:
1)thehydrogenationofcarbonoxidesformethanolsynthesis,
2
3
(
solid acid catalysts: (1) methanol synthesis, (2) methanol
dehydration, and (3) shift reaction.
and (2) the solid surface acidity for methanol dehydration.
Several attempts have been made to give the two functional-
ities of methanol synthesis and methanol dehydration in a cat-
8–10
CO + 3H $ CH OH + H O
ð1Þ
ð2Þ
ð3Þ
alyst preparation step,
but the admixed catalysts of
2
2
3
2
methanolsynthesiscatalyst andsolidacidcatalystshowed bet-
ter performances in the aspects of the apparent activity. The
key reason for this behavior is the high specific Cu surface
areas of the admixed catalysts.
2
CH3OH $ CH3OCH3 + H2O
CO + H O $ CO + H
2
2
2
Bull. Korean Chem. Soc. 2015, Vol. 36, 1221–1225
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Article
Relative Roles of Methanol Synthesis Catalyst and Solid Acid Catalyst
KOREAN CHEMICAL SOCIETY
ꢀ
Several attempts have also been made to modify the solid
was calcined 600 C for 6 h. η-Al O was initially prepared by
2
3
ꢀ
acid catalysts in the admixed catalysts to enhance the direct
DME activity. The overall STD reaction rate can be controlled
by the relative activity of methanol synthesis and methanol
dehydration. Many studies have shown that Cu surface areas
mixing 124 g ATSB and 1800 mL water (25 C). The solution
was maintained for 24 h after stirring for 1 h. It was then centri-
fuged to get the precipitate. The sample was dried at 110 C for
ꢀ
ꢀ
24 h. The resulting dried sample was calcined at 600 C for 6 h.
11–14
were correlated with methanol synthesis activity.
It
The γ-Al O catalystwas denoted as LD(lowactive catalystfor
2
3
means that the Cu surface area can be correlated with the
CO conversion in the STD synthesis. On the other hand, it
was reported that the overall rate of the STD reaction was
determined by the acid properties of solid acid catalysts in
methanol dehydration) and the η-Al O catalyst was denoted as
2
3
HD (highly active catalyst for methanol dehydration).
Characterization. Acidity measurements were performed via
temperature programmed adsorption of ammonia with a quad-
ruple mass spectrometer (QMS, Pfeiffer Vacuum, Asslar,
6
,15,16
methanol dehydration.
Therefore, STD synthesis rate
ꢀ
can be determined by the admixed ratio of methanol synthesis
and methanol dehydration catalysts.
Germany) in the temperature range RT to 800 C. Ammonia
was adsorbed on the catalyst sample at RT for 1 h. Ammonia
TPD (temperature programmed desorption) experiments were
conducted after the physisorbed ammonia was removed with a
He flow for 1 h at 120 C. The mass detector was calibrated
from thedesorption data ofa known amount of ammonia using
a six port valve with a sample loop of 0.5 mL. The BET
(Brunauer Emmet Teller) surface areas of the calcined cata-
lysts were measured by nitrogen physisorption at –196 C
In this study, the Cu/ZnO/Al O catalysts with twodifferent
2
3
activities were chosen for methanol synthesis, and the Al O3
2
ꢀ
catalysts with two different activities were also selected for
methanol dehydration. Twenty-two different admixed cata-
lysts were prepared, and the roles of methanol synthesis and
methanol dehydration catalysts are discussed.
18
ꢀ
Experimental
using a Micromeritics ASAP 2000 instrument (Norcross,
GA, USA). Prior to the measurements, the catalysts were
ꢀ
Catalyst Preparation
degassed at 200 C for 2 h. Cu surface areas, S , were deter-
Cu
Methanol Synthesis Catalyst. The methanol synthesis cata-
lysts with the mol ratio of Cu:Zn:Al = 6:3:1 were prepared
by a coprecipitation method from their nitrate solution at a
pH ~7.0. A buffer solution of pH 8 containing a mixture of
Na CO and NaHCO was used as the precipitation agent.
mined by N O titrations. Typically, 50 mg of the catalysts was
2
ꢀ
reduced under a 5% H /Ar gas stream at 250 C for 2 h, and
2
ꢀ
the reactor was purged with He gas at 150 C for 0.5 h. N O
2
titrations were carried out after the reactor was cooled down
ꢀ
to 90 C. In this investigation, a surface copper density of
2
3
3
19
2
Typically, Cu(NO ) ꢁ3H O, Zn(NO )ꢁ6H O, and Al(NO )ꢁ
1.47 × 10 atoms/m was used for calculating the copper
metal area.
3
2
2
3
2
3
19
9
H O were dissolved in distilled water to get a 0.3 M metal
2
nitrate solution. The buffer solution was added to the aqueous
metal nitrate solution under vigorous agitation at room temper-
ature, and the initial pH of the slurry was maintained in the
range7.0–7.5. Theprecipitatewas filtered and washedwithdis-
tilled water after aging for 12 and 36 h at room temperature.
Thewashedsamplesweredriedinavacuumovenfor24 hat
Activity Measurement. Catalytic activity measurements were
carried out in a fixed-bed tubular reactor (i.d. = 3/8 in.) loaded
with 0.1 g of the catalysts. The products were analyzed using
an online GC equipped with a thermal conductivity detector
(TCD) using Porapak Q and Carbosphere columns (Agilant,
Santa Clara, CA, USA) in series. For methanol synthesis,
the prepared catalysts were pre-reduced in 5% H /N gas at
ꢀ
ꢀ
100 C. The driedsamples werecalcined at450 Cfor6 h. The
2
2
ꢀ
activity of prepared catalysts for methanol synthesis was
250 C for 5 h. After the reduction, the feed gases (CO in car-
2
1
7
dependent on the aging time. Two catalysts with the aging
time of 12 and 36 h were chosen to investigate the effect of
the activity of methanol synthesis on the admixed catalysts
for DME synthesis. The catalysts prepared with the aging time
of 12 and 36 h were designated as LM (low activity catalysts
for methanol synthesis) and HM (high activity catalysts for
methanol synthesis), respectively.
bon oxide: 20%, (H -CO )/(CO + CO ): 3.0) were introduced
2
2
2
ꢀ
into the reactor at 50 atm and 250 C. For methanol dehydra-
tion reaction, methanol was introduced into the reactor with
the solid acid catalysts at atmospheric pressure and 250 C.
ꢀ
For the STD reaction, the admixed catalysts of Cu/Zn/
Al O andalumina were reduced under a5% H /N gas stream
2
3
2
2
ꢀ
at 300 C for 3 h. After the reduction, a gas mixture of H and
2
Methanol Dehydration Catalyst. The γ- and η-Al O cata-
CO with 1:1.5 molar ratio of H /CO was introduced into the
2
3
2
lysts were prepared from boehmite and bayerite calcined
reactor at a GHSV (gas hourly space velocity) of 6000 mL/
ꢀ
at different temperatures by a sol–gel process according
g ./h, 42 atm, and 250 C.
cat
1
8
to a previous report. γ-Al O was prepared using the
2
3
Yoldas method. ATSB (124 g, aluminum tri-sec-butoxide,
Results and Discussion
ACROS organics, 97%) was added dropwise to distilled water
ꢀ
(
80 C, 900 mL) for 30 min under vigorous stirring. Then,
Methanol Synthesis on Cu/Zn/Al O Catalysts. Methanol
2
3
0
3
.8 mL of HCl (SamChun Chemicals, Seoul, S. Korea,
5–37%) was added with stirring, and a boehmite gel formed.
synthesis was performed to investigate the catalytic activity of
LM and HM catalysts in the GHSV range 12 000–48 000 mL/
ꢀ
The gel was subsequently centrifuged at 2500 rpm for 30 min
and then dried at 110 C for 24 h. The resulting dried sample
g /h at 250 C and 50 atm. The molar content of CO in car-
cat
2
ꢀ
bon oxides in feed was 20% at the R ((H -CO)/(CO + CO ))
2 2
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BULLETIN OF THE
Article
Relative Roles of Methanol Synthesis Catalyst and Solid Acid Catalyst
KOREAN CHEMICAL SOCIETY
ratio of 3.0. Figure 1 shows the yield of methanol on the LM
and HM catalysts with respect to the space time. The Cu sur-
catalytic performance of HD (η-Al O ) and LD (γ-Al O ) cat-
2
3
2 3
ꢀ
alysts under atmospheric pressure and 250 C.
face areas of the prepared LM and HM catalysts were 13.0 and
Figure 2 shows the methanol conversion with respect to
space time on the LM and HM catalysts. It was observed that
η-Al O showed better catalytic performance than γ-Al O .
2
3
0.6 m /g, respectively. The BET surface areas of the LM and
2
HM catalysts were 103.1 and 201.2 m /g, respectively. The
initial rates of LM and HM catalysts were estimated to be
2
3
2 3
The initial specific rates of the γ-Al O and η-Al O catalysts
2
3
2 3
1
1.9 and 26.7 μmol/g /s. The initial rates were linear with
were calculated as 0.38 and 0.30 mmol/g /s, respectively.
cat
cat
respect to the specific Cu surface area under the same reaction
conditions. R from a linear regression (the coefficient of
The BET surface areas and total acidities of the LD catalyst
2
2
were 201 m /g and 47.8 μmol/g, respectively, while those of
2
determination) was 0.9997. The initial specific activity of
the prepared Cu/ZnO/Al O catalysts was also calculated to
the HD catalyst were 162 m /g and 58.1 μmol/g. The acid site
densities of the LD and HD catalysts were evaluated to be 0.24
2
3
2
2
be 0.90 μmol/m Cu/s from the linear regression. Chinchen
et al. found that the activity of Cu-based catalysts was linear
and 0.36 μmol/m . The higher activity of HD was ascribed
mainly to the high acid site density from these experimental
results. Additionally, itwassuggestedthatthehexagonalpillar
structure oftheHDcatalyst canbeacrucial factorinenhancing
2
0
with respect to Cu surface areas irrespective of the supports.
2
The specific activity of Cu-based catalysts was 0.26 μmol/m
ꢀ
18
Cu/s at 50 atm and 240 C. Griffin et al. also reported that the
the dehydration activity as compared to LD catalyst.
2
initial specific activity of Cu/ZnO catalysts was 0.26 μmol/m
STD Synthesis on the Four Different Admixed Ratio Cat-
alysts. Four different DME synthesis catalytic systems were
prepared by admixing two methanol synthesis catalysts (HM
and LM) and two DME hydration catalysts (HD and LD).
ꢀ
Cu/s under the reaction conditions of 250 C, 50 atm, and
2
1
H /CO/CO = 70/24/6. Later, it was shown that the specific
2
2
activity of Cu/ZnO was linearly dependent on the Cu
surface area, although the synergistic effects of Cu and ZnO
22
were emphasized. Spencer noted that the synergistic effects
were not observed in high GHSV, supporting the insensitivity
LMLD: Admixed catalytic system of LM and LD
LMHD: Admixed catalytic system of LM and HD
HMLD: Admixed catalytic system of HM and LD
HMHD: Admixed catalytic system of HM and HD
23,24
of the surface of Cu/ZnO catalysts in CO hydrogenation.
2
The structure insensitivity of Cu/ZnO/Al O was also noted in
2
3
the correlation between the catalyst structure and activity of a
large set of Cu/ZnO/Al O catalysts for methanol synthesis.
Twenty-two admixed DME catalysts were prepared by
changing the composition of methanol synthesis andmethanol
dehydration catalysts for each of the four different catalytic
systems. DME synthesis was conducted at a GHSV of 6000
2
3
Recently, the specific activity of the prepared catalysts was
2
evaluated to be 0.51 μmol/m Cu/s under the reaction condi-
tions of GHSV = 24 000 mL/g /h (H /CO/CO = 70/24/6),
cat
2
2
ꢀ
25
ꢀ
4
5 atm, and 245 C. The high initial specific activity
mL/gcat/h, 4.2 atm, and 250 C. The pressure of 4.2 atm was
2
noted in this work, 0.90 μmol/m Cu/s, could be due to higher
R ratio (R = 3.0) as compared with the reported reaction con-
dition (R = 2.1).
chosen for comparison with previous results in our laboratory.
Figure 3 shows the DME yields and DME selectivity of the
prepared admixed catalysts. DME selectivity was observed in
the range 61.0–68.0%, following the stoichiometry of the
reaction: 3CO + 3H ! CH OCH + CO . CO and DME
Methanol Dehydration on γ- and η-Al O Catalysts.
2
3
Methanol dehydration was performed to investigate the
2
3
3
2
2
8
6
4
2
0
0
0
0
0
6
5
4
3
2
1
0
0
0
0
0
0
0
0
.0
0.5
1.0
1.5
2.0
0
3
6
9
W/F(CO+CO ) (g *h/mol)
cat
W/FMeOH (g h/mol)
cat
2
−
1
Figure 1. Methanol yield in the GHSV range 12 000–48 000 h over
Figure 2. Methanol conversion in the methanol dehydration in the
−
1
(
) HM and ( ) LM catalysts in the methanol synthesis reaction at
GHSV range 12 000–48 000 h over ( ) HD and ( ) LD catalysts
ꢀ
ꢀ
5
0 atm and 250 C.
in methanol dehydration at atmospheric pressure and 250 C.
Bull. Korean Chem. Soc. 2015, Vol. 36, 1221–1225
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BULLETIN OF THE
Article
Relative Roles of Methanol Synthesis Catalyst and Solid Acid Catalyst
KOREAN CHEMICAL SOCIETY
were mainly produced, and methanol was rarely detected in all
thereactions. IntheLMcatalytic system, DMEyieldswerenot
much dependent on the activity of methanol dehydration cat-
alysts, but they did on the acid catalyst composition in the
admixed catalysts. However, in the HM catalytic system with
the acid catalyst composition higher than 40%, DME yields
were very much dependent on the activity of methanol dehy-
dration catalyst as well as on the acid catalyst composition of
the admixed catalysts. In the HM catalytic system with acid
catalyst composition lower than 20 wt%, DME yields of
HMLD were the same as those of HMHD but slightly
decreased with the decrease in the acid catalyst composition.
These experimental results show that the activity of the
admixed catalysts with LM was not so much dependent on
the activity of the solid acid catalysts in direct DME synthesis,
but those with HM were strongly influenced by the activity of
the solid acid catalysts. In the previous report on the admixed
Another clear finding is that the activity of the admixed cat-
alysts increased with a decrease in the solid acid composition.
The decrease in activity of the admixed catalysts with the solid
acid catalyst lower than 20 wt% in HMLD and HMHD can be
due to the relatively high activity of the methanol synthesis
catalysts. Such types of DME yield decrease were not
observed in the admixed catalytic system of Katalco 33-5
and H-ZSM-5 catalysts in previous reports, which can be
due to the high acidic character of H-ZSM-5. Apparently,
the specific Cu surface areas of the admixed catalysts should
increase with a decrease in the solid acid composition of the
admixed catalysts. Therefore, it indicates that the activity of
the admixed catalysts can increase with an increase in the spe-
cific Cu surface area of the admixed catalysts. The importance
of the specific Cu surface area of the admixed catalysts has
11–14
been reported.
In that point, all the activity data were plot-
ted with respect to the specific Cu surface area as shown
in Figure 4. Interestingly, CO conversions of three catalytic
systems of LMLD, LMHD and HMHD except HMLD were
similar with respect to the specific Cu surface area.
2
catalysts of Katalco 33-5 (methanol synthesis catalyst, 23 m
Cu/g) and Na-ZSM-5 (methanol dehydration catalyst, Si/Al =
1
1
3
0) under the same reaction condition, DME yields were
intermediate between LMLD and HMLD in this report.
It is clear that the most important factor is the specific Cu
surface area of the admixed DME catalysts. However, the cat-
alytic system of HMLD showed a weak dependency on the
specific Cu surface area but a strong dependency on the activ-
ity of the solid acid catalyst. Therefore, the second importance
of the admixed catalytic system should be given to the activity
ofthemethanol dehydrationcatalyst if theactivity ofmethanol
synthesis catalyst is sufficiently high compared to the activity
of the solid acid catalysts. Usually, the admixed catalysts with
the weight ratio of 1:1 of Cu/ZnO/Al O to solid acid catalyst
2
The Cu surface area of Katalco 33-5 (23 m Cu/g) was in
2
between the surface areas of LM (13.0 m Cu/g) and HM
2
(
30.6 m Cu/g). Several publications have focused on the
activity of methanol dehydration of the admixed catalysts
6
,8–10,15,16
for direct DME synthesis.
However, the effects of
the solid acid catalysts can be discussed with the relative activ-
ity of methanol synthesis catalysts. If relatively more active
methanol synthesis catalysts as compared with the solid acid
catalysts were used, the activity of the solid acid catalysts
wouldbeveryimportantfortheactivityofthedirectDMEsyn-
thesis catalysts (HMLD and HMHD). On the other hand, if rel-
atively less active methanol synthesis catalysts were used, the
activity of the solid acid catalysts would not be much depend-
ent on the activity of the direct DME synthesis catalysts
2
3
have been tested to investigate the role of the solid acid cata-
lysts for direct DME synthesis. With 1:1 weight ratio of Cu/
ZnO/Al O to solid acid catalyst, DME yields of HMLD
2
3
and HMLE were 42.5 and 17.3%, respectively, as shown in
Figure 3. It indicates that the activity of solid acid catalysts
(LMLD and LMHD).
100
80
60
40
20
0
8
0
0
6
40
20
0
0
5
10
15
20
25
2
30
0
20
40
60
80
100
Cu surface area of the admixed catalysts (m Cu/g )
cat
Acid catalyst composition in admixed catalysts (wt%)
Figure 4. CO conversion with respect to the specific Cu surface areas
of the admixed catalysts under the reaction condition of 250 C, 42
bar, and a GHSV of 6000 mL/gcat/h: ( ) LMLD, ( ) LMHD, ( )
HMLD, ( ) HMHD.
ꢀ
Figure 3. DME conversion (filled symbols) and selectivity (empty
symbol) withrespect tothe solid acid compositioninthe admixed cat-
alysts: ( ) LMLD, ( ) LMHD, ( ) HMLD, ( ) HMHD.
Bull. Korean Chem. Soc. 2015, Vol. 36, 1221–1225
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BULLETIN OF THE
Article
Relative Roles of Methanol Synthesis Catalyst and Solid Acid Catalyst
KOREAN CHEMICAL SOCIETY
can control the overall STD reaction on the admixed catalysts
with highly active Cu/ZnO/Al O catalysts.
4. K. Fujimoto, K. Asami, T. Shikada, H. Tominaga, Chem. Lett.
984, 12, 2051.
. K. L. Ng, D. Chadwick, B. A. Toseland, Chem. Eng. Sci. 1999,
4, 3587.
. T. Takeguchi, K. Yanagiwa, T. Inui, M. Inoue, Appl. Catal. A
000, 192, 201.
. G. Qi, X. Zheng, J. Fei, Z. Hou, J. Mol. Catal. 2001,
76, 195.
1
2
3
5
6
7
8
5
Conclusion
2
The CO conversions with LMLD, LMHD, and HMHD cata-
lytic systems were almost same with respect to the specific
Cu surface area, indicating that the surface area is a main
controlling factor in the STD reaction. Especially on the
1
. G. Yang, N. Tsubaki, J. Shamoto, Y. Yoneyama, Y. Zhang,
J. Am. Chem. Soc. 2010, 132, 8129.
admixed catalysts with the specific Cu surface areas below
9. R. Ahmad, D. Schrempp, S. Behrens, J. Sauer, M. Döring,
U. Arnold, Fuel Process. Technol. 2014, 121, 38.
2
1
8.3 m Cu/g , the activity of the admixed DME catalysts
cat
linearly increased with increase in the surface area. The influ-
ence of the solid acid catalysts on the admixed catalysts with
the LM catalyst was negligible. However, the activity of solid
acid catalysts became important on the admixed catalysts with
the HM catalyst.
10. Y. J. Lee, M. H. Jung, J. B. Lee, K. E. Jeong, H. S. Roh, Y. W.
Suh, J. W. Bae, Catal. Today 2014, 228, 175.
1
1
1
1
1. J. H. Kim, M. J. Park, S. J. Kim, O. S. Joo, K. D. Jung, Appl.
Catal. A 2004, 264, 37.
2. A. Venugopal, J. Palgunadi, K. D. Jung, O. S. Joo, C. Shin,
J. Mol. Catal. 2009, 302, 20.
3. A. Venugopal, J. Palgunadi, K. D. Jung, O. S. Joo, C. H. Shin,
Catal. Today 2009, 147, 94.
4. K. S. Yoo, J. H. Kim, M. J. Park, S. J. Kim, O. S. Joo, K. D. Jung,
Appl. Catal. A 2007, 330, 57.
CO conversions on the LMLD, LMHD, HMLD, and
HMHD catalytic systems with Cu surface areas higher than
2
2
5 m Cu/g showed the same values, which were close to
cat
the maximized CO conversion of HMHD. Based on the exper-
imental results, the first importance should be given to increas-
ing the Cu surface areas of methanol synthesis catalysts in the
admixed catalysts. On the other hand, the solid acid catalysts
can play a role in controlling the STD reaction on the admixed
catalysts with the highly active methanol catalysts.
15. F. S. Ramos, A. M. Duarte de Farias, L. E. P. Borges, J. L. Mon-
teiro, M. A. Fraga, E. F. Sousa-Aguiar, L. G. Appel, Catal. Today
2005, 101, 39.
1
6. A. Garcia-Trenco, A. Martinez, Appl. Catal. A 2012,
11, 170.
4
1
7. H. Jung, D. R. Yang, O. S. Joo, K. D. Jung, Bull. Korean Chem.
Soc. 2010, 31, 1241.
Acknowledgments. Theauthorswish tothank theMinistry of
Science, ICT and Future Planning for financial support
through a Korea CCS R&D Center (KCRC) grant and through
the Nuclear Hydrogen Development and Demonstration
18. C. W. Seo, K. D. Jung, K. Y. Lee, K. S. Yoo, Ind. Eng. Chem.
Res. 2008, 47, 6573.
1
2
2
9. J. W. Evans, M. S. Wainwright, A. J. Bridgewater, D. Young,
J. Appl. Catal. 1983, 7, 75.
0. G. C. Chinchen, K. C. Waugh, D. A. Whan, Appl. Catal. 1986,
(NHDD) project.
2
5, 101.
1. W. X. Pan, R. CaO, D. L. Robert, G. L. Griffin, J. Catal. 1998,
14, 440.
References
1
1
2
3
. T. A. Semelsberger, R. L. Borup, H. L. Greene, J. Power Sources
006, 156, 497.
. C. Arcoumanis, C. Bae, R. Crookes, E. Kinoshita, Fuel 2008,
7, 1014.
. http://www.aboutdme.org, IDA fact sheet No 2 published by Int.
DME association, 2010.
2
2
2
2. M. S. Spencer, Top. Catal. 1999, 8, 259.
2
3. G. C. Chinchen, M. S. Spencer, Catal. Today 1991, 10, 293.
4. R. Burch, S. E. Golunski, M. S. Spencer, J. Chem. Soc. Faraday
Trans. 1990, 86, 2683.
8
2
5. C. Baltes, S. Vukojevic, S. Schuth, J. Catal. 2008, 258, 334.
Bull. Korean Chem. Soc. 2015, Vol. 36, 1221–1225
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