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sion of carbon dioxide and the selectivity into methanol. However, the selection of
these parameters must take into account other factors including the kinetic constant
rate of the reaction, the catalyst activation, the cost of the materials for the reactor
design which strongly depends on the temperature and pressure, and the global
energy balance of the process.
5.3 Selective Hydrogenation of Carbon Dioxide to Methanol
in the Gas Phase: Heterogeneous Catalysis
The first catalytic process for methanol synthesis was developed in 1913 by BASF,
with syngas, which mainly contains carbon monoxide, carbon dioxide, and hydrogen, produced from coal as reactant mixture (Lee 1990). The “high-pressure methanol synthesis” process was implemented in Germany in 1923; the catalytic reactor
was based on a ZnO/Cr 2 O 3 catalyst and was operated between 300 and 400 °C under
pressures of 250–300 bar (Goeppert et al. 2014; Lange 2001). With the use of natural gas instead of coal and the production of syngas with less impurity, more efficient copper-based catalysts were progressively used allowing softer reaction
conditions (Lee 1990; Cheng and Kung 1994; Gent 1976). The “low-pressure methanol synthesis” process, which operates between 200 and 300 °C under pressures of
50–100 bar, with a CuO–ZnO–Al 2 O 3 catalyst, is still used to produce methanol from
mixtures containing carbon monoxide, carbon dioxide, and hydrogen resulting from
steam reforming of natural gas.
Meanwhile, numerous studies aimed to understand the role of carbon dioxide in
the hydrogenation of a mixture of carbon monoxide and carbon dioxide. Some of
these concluded that carbon dioxide is first converted into carbon monoxide by the
reverse water-gas shift reaction and that only carbon monoxide is hydrogenated into
methanol (Boomer and Morris 1932). Other studies proposed at the contrary that the
hydrogenation of carbon dioxide into methanol is much faster than that of carbon
monoxide (Kieffer et al. 1981; Lee et al. 1993; Wang et al. 2010).
The number of articles devoted specifically to the hydrogenation of carbon dioxide into methanol recently increased dramatically, along with the research for
anthropic carbon dioxide conversion.
In the following sections, conventional copper-based catalysts for conventional
heterogeneous gas/solid “thermal” catalysis will be discussed, and their activity will
be compared to more “exotic” materials, free of copper. Then, nonconventional activation modes for the hydrogenation of carbon dioxide to methanol in the gas phase
will be discussed. The kinetic and mechanistic studies will be also reviewed.
D. P. Minh et al.
sion of carbon dioxide and the selectivity into methanol. However, the selection of
these parameters must take into account other factors including the kinetic constant
rate of the reaction, the catalyst activation, the cost of the materials for the reactor
design which strongly depends on the temperature and pressure, and the global
energy balance of the process.
5.3 Selective Hydrogenation of Carbon Dioxide to Methanol
in the Gas Phase: Heterogeneous Catalysis
The first catalytic process for methanol synthesis was developed in 1913 by BASF,
with syngas, which mainly contains carbon monoxide, carbon dioxide, and hydrogen, produced from coal as reactant mixture (Lee 1990). The “high-pressure methanol synthesis” process was implemented in Germany in 1923; the catalytic reactor
was based on a ZnO/Cr 2 O 3 catalyst and was operated between 300 and 400 °C under
pressures of 250–300 bar (Goeppert et al. 2014; Lange 2001). With the use of natural gas instead of coal and the production of syngas with less impurity, more efficient copper-based catalysts were progressively used allowing softer reaction
conditions (Lee 1990; Cheng and Kung 1994; Gent 1976). The “low-pressure methanol synthesis” process, which operates between 200 and 300 °C under pressures of
50–100 bar, with a CuO–ZnO–Al 2 O 3 catalyst, is still used to produce methanol from
mixtures containing carbon monoxide, carbon dioxide, and hydrogen resulting from
steam reforming of natural gas.
Meanwhile, numerous studies aimed to understand the role of carbon dioxide in
the hydrogenation of a mixture of carbon monoxide and carbon dioxide. Some of
these concluded that carbon dioxide is first converted into carbon monoxide by the
reverse water-gas shift reaction and that only carbon monoxide is hydrogenated into
methanol (Boomer and Morris 1932). Other studies proposed at the contrary that the
hydrogenation of carbon dioxide into methanol is much faster than that of carbon
monoxide (Kieffer et al. 1981; Lee et al. 1993; Wang et al. 2010).
The number of articles devoted specifically to the hydrogenation of carbon dioxide into methanol recently increased dramatically, along with the research for
anthropic carbon dioxide conversion.
In the following sections, conventional copper-based catalysts for conventional
heterogeneous gas/solid “thermal” catalysis will be discussed, and their activity will
be compared to more “exotic” materials, free of copper. Then, nonconventional activation modes for the hydrogenation of carbon dioxide to methanol in the gas phase
will be discussed. The kinetic and mechanistic studies will be also reviewed.
D. P. Minh et al.