565
2
6
3
123 0
2
2
3
3
2
CO
H
CH OCH
H O
kJ mol
+
↔
+
= −
°
∆H
.
/
(11)
Shen et al. [29] reported higher CO 2 equilibrium conversion for single step CO 2
conversion to DME than CO 2 conversion to methanol. The equilibrium DME yield
decreased with temperature and increased with pressure in accordance to Le
Chatelier’s principle. Aguayo et al. [30] proposed a kinetic model for single pot
DME synthesis using conventional Cu-ZnO-Al 2 O 3 /γ-Al 2 O 3 hybrid bifunctional catalyst with CO/H 2 and CO 2 /H 2 as feed. In their proposed model, the main reactions
that were considered are methanol synthesis, its subsequent dehydration, hydrocarbon synthesis, and water gas shift reaction. Similar results were also reported for
Cu–Fe 2 O 3 –ZrO 2 /H-ZSM-5 catalyst using intrinsic kinetic model for single step CO 2
hydrogenation to DME [31]. The above studies show that single step DME synthesis has the thermodynamic advantages in terms of CO 2 conversion, methanol, and
DME yield.
1.4 Methanol Chemistry
1.4.1 Catalysts
In the early 1920s and 1930s, more active copper-based catalysts were studied and
described. Copper was identified as a quite active metal for synthesis of methanol in
these early studies. The activity was found to be increased when it was used along
with the ZnO and stabilized with Al 2 O 3 . Workers at ICI pioneered the efforts in the
area of methanol synthesis [32, 33], and by now, the Cu/ZnO/Al 2 O 3 catalyst is
almost exclusively used. Few formulations for state of the art/commercial methanol
synthesis catalyst are briefly described in the following Table 2.
The catalyst for methanol synthesis is combined with solid acid (for methanol
dehydration) for making the hybrid bifunctional catalyst for DME synthesis by various methods, viz., physical mixing, ball milling, impregnation, etc. The prevailing
combination method is physical mixing of powder or granules of each component.
The catalytic entity for DME synthesis contains dual active sites, one for methanol
Table 2 Commercial methanol synthesis catalyst formulations [10]
Manufacturer→
Description↓
BASF
DuPont
Haldor Topsoe
ICI
Copper
38.5
50
>55
20–35
Zinc
48.8
19
21–25
15–50
Aluminium
12.9
17
8–10
4–20
Others
Rare earth oxides
–
–
Mg
Feedstock
Syngas
Syngas
Syngas
Carbonaceous
Yield (tons/year)
28.82
41.61
87.6 × 10
4
91.25 × 10
4
Patent date
1978
–
–
1965
Perspectives in Carbon Oxides Conversion to Methanol/Dimethyl Ether: Distinctive…
2
6
3
123 0
2
2
3
3
2
CO
H
CH OCH
H O
kJ mol
+
↔
+
= −
°
∆H
.
/
(11)
Shen et al. [29] reported higher CO 2 equilibrium conversion for single step CO 2
conversion to DME than CO 2 conversion to methanol. The equilibrium DME yield
decreased with temperature and increased with pressure in accordance to Le
Chatelier’s principle. Aguayo et al. [30] proposed a kinetic model for single pot
DME synthesis using conventional Cu-ZnO-Al 2 O 3 /γ-Al 2 O 3 hybrid bifunctional catalyst with CO/H 2 and CO 2 /H 2 as feed. In their proposed model, the main reactions
that were considered are methanol synthesis, its subsequent dehydration, hydrocarbon synthesis, and water gas shift reaction. Similar results were also reported for
Cu–Fe 2 O 3 –ZrO 2 /H-ZSM-5 catalyst using intrinsic kinetic model for single step CO 2
hydrogenation to DME [31]. The above studies show that single step DME synthesis has the thermodynamic advantages in terms of CO 2 conversion, methanol, and
DME yield.
1.4 Methanol Chemistry
1.4.1 Catalysts
In the early 1920s and 1930s, more active copper-based catalysts were studied and
described. Copper was identified as a quite active metal for synthesis of methanol in
these early studies. The activity was found to be increased when it was used along
with the ZnO and stabilized with Al 2 O 3 . Workers at ICI pioneered the efforts in the
area of methanol synthesis [32, 33], and by now, the Cu/ZnO/Al 2 O 3 catalyst is
almost exclusively used. Few formulations for state of the art/commercial methanol
synthesis catalyst are briefly described in the following Table 2.
The catalyst for methanol synthesis is combined with solid acid (for methanol
dehydration) for making the hybrid bifunctional catalyst for DME synthesis by various methods, viz., physical mixing, ball milling, impregnation, etc. The prevailing
combination method is physical mixing of powder or granules of each component.
The catalytic entity for DME synthesis contains dual active sites, one for methanol
Table 2 Commercial methanol synthesis catalyst formulations [10]
Manufacturer→
Description↓
BASF
DuPont
Haldor Topsoe
ICI
Copper
38.5
50
>55
20–35
Zinc
48.8
19
21–25
15–50
Aluminium
12.9
17
8–10
4–20
Others
Rare earth oxides
–
–
Mg
Feedstock
Syngas
Syngas
Syngas
Carbonaceous
Yield (tons/year)
28.82
41.61
87.6 × 10
4
91.25 × 10
4
Patent date
1978
–
–
1965
Perspectives in Carbon Oxides Conversion to Methanol/Dimethyl Ether: Distinctive…