129
tions orders to both carbon dioxide and hydrogen are much higher for the doped
catalysts than for the commercial catalyst, suggesting a greater influence of the total
partial pressure on the rate of methanol synthesis for these catalysts. For example,
carbon dioxide and hydrogen reactions orders obtained with the catalyst doped with
zirconium were 0.94 and 1.71, respectively, while carbon dioxide and hydrogen
reactions orders obtained with the commercial catalyst were 0.52 and 1.34.
Maximilian and co-workers ( 2012) compared three different approaches to
develop kinetic models for methanol synthesis, e.g., power law, Langmuir–
Hinshelwood–Hougen–Watson, and a microkinetic model developed by Ovesen
and co-workers (1996). The experiments were performed over a Cu–ZnO–Al 2 O 3
catalyst at temperatures ranging from 190 to 250 °C and pressures ranging from 5
to 60 bar. Similar to the results obtained by Kobl and co-workers (2016), the power
law model showed that hydrogen partial pressure was one of the most influencing
parameters on the methanol production and that the reverse water-gas shift reaction
had little influence on the rate of methanol formation. In the Langmuir–Hinshelwood–
Hougen–Watson model, carbon dioxide was assumed to be the main source of carbon in the methanol production, and both carbon dioxide and hydrogen would
adsorb on the same type of active site. The adsorbed carbon dioxide would lead to
carbonate structures, which are then hydrogenated for further methanol production.
Results obtained with the Langmuir–Hinshelwood–Hougen–Watson model were
very similar to those obtained with the power law model. A sensitivity analysis
showed that the hydrogen adsorption constant was also one of the most influencing
Table 5.3 Kinetic studies on CO 2 hydrogenation to methanol
Catalyst
Temperature
(°C)
Pressure
(bar)
Reactions
involved
Type of model
References
Cu–ZnO–
Al 2 O 3 and
Cu–ZnO–ZrO
200–240
50–80
1, 2, 3
Power law
Kobl et al.
(2016)
Cu–ZnO–
Al 2 O 3
250–340
50–90
1, 2, 3
Langmuir–
Hinshelwood–
Hougen–Watson
Park et al.
(2014)
Cu–ZnO–
Al 2 O 3
190–250
5–60
1, 2, 3
Power law, Langmuir–
Hinshelwood–
Hougen–Watson,
Ovesen
Maximilian
et al. (2012)
Cu–ZnO–
Al 2 O 3
180–280
15–51
1, 2, 3
Microkinetic (Van den
Bussche and Froment)
Van den
Bussche and
Froment (1996)
Cu–ZnO–
Al 2 O 3 , Cu/
Al 2 O 3 , and Cu/
SiO 2
180–220
5–20
2
Microkinetic (Ovesen) Ovesen et al.
(1996)
Cu–ZnO–
Al 2 O 3 , Cu/Zn/
Al/Mg, and
Cu/Zn/Al/Zr
220–260
23.7–30 1, 2, 3
Power law, Van den
Bussche and Froment
Stanislaw et al.
(2013)
5 Selective Hydrogenation of Carbon Dioxide into Methanol
tions orders to both carbon dioxide and hydrogen are much higher for the doped
catalysts than for the commercial catalyst, suggesting a greater influence of the total
partial pressure on the rate of methanol synthesis for these catalysts. For example,
carbon dioxide and hydrogen reactions orders obtained with the catalyst doped with
zirconium were 0.94 and 1.71, respectively, while carbon dioxide and hydrogen
reactions orders obtained with the commercial catalyst were 0.52 and 1.34.
Maximilian and co-workers ( 2012) compared three different approaches to
develop kinetic models for methanol synthesis, e.g., power law, Langmuir–
Hinshelwood–Hougen–Watson, and a microkinetic model developed by Ovesen
and co-workers (1996). The experiments were performed over a Cu–ZnO–Al 2 O 3
catalyst at temperatures ranging from 190 to 250 °C and pressures ranging from 5
to 60 bar. Similar to the results obtained by Kobl and co-workers (2016), the power
law model showed that hydrogen partial pressure was one of the most influencing
parameters on the methanol production and that the reverse water-gas shift reaction
had little influence on the rate of methanol formation. In the Langmuir–Hinshelwood–
Hougen–Watson model, carbon dioxide was assumed to be the main source of carbon in the methanol production, and both carbon dioxide and hydrogen would
adsorb on the same type of active site. The adsorbed carbon dioxide would lead to
carbonate structures, which are then hydrogenated for further methanol production.
Results obtained with the Langmuir–Hinshelwood–Hougen–Watson model were
very similar to those obtained with the power law model. A sensitivity analysis
showed that the hydrogen adsorption constant was also one of the most influencing
Table 5.3 Kinetic studies on CO 2 hydrogenation to methanol
Catalyst
Temperature
(°C)
Pressure
(bar)
Reactions
involved
Type of model
References
Cu–ZnO–
Al 2 O 3 and
Cu–ZnO–ZrO
200–240
50–80
1, 2, 3
Power law
Kobl et al.
(2016)
Cu–ZnO–
Al 2 O 3
250–340
50–90
1, 2, 3
Langmuir–
Hinshelwood–
Hougen–Watson
Park et al.
(2014)
Cu–ZnO–
Al 2 O 3
190–250
5–60
1, 2, 3
Power law, Langmuir–
Hinshelwood–
Hougen–Watson,
Ovesen
Maximilian
et al. (2012)
Cu–ZnO–
Al 2 O 3
180–280
15–51
1, 2, 3
Microkinetic (Van den
Bussche and Froment)
Van den
Bussche and
Froment (1996)
Cu–ZnO–
Al 2 O 3 , Cu/
Al 2 O 3 , and Cu/
SiO 2
180–220
5–20
2
Microkinetic (Ovesen) Ovesen et al.
(1996)
Cu–ZnO–
Al 2 O 3 , Cu/Zn/
Al/Mg, and
Cu/Zn/Al/Zr
220–260
23.7–30 1, 2, 3
Power law, Van den
Bussche and Froment
Stanislaw et al.
(2013)
5 Selective Hydrogenation of Carbon Dioxide into Methanol