Nanotechnologies / Materials
Catalysis chemistry, Petroleum chemistry, Carbon neutral

Development of advanced catalytic technology forutilization of carbon dioxide at low temperature

山下 弘巳

Division of Materials and Manufacturing Science, Graduate School of Engineering
Associate Professor Yasutaka Kuwahara

Researchmap https://researchmap.jp/yasutakakuwahara/

Professor Hiromi Yamashita

Researchmap https://researchmap.jp/read0118536

Nanotechnologies / Materials

Abstract
Carbon dioxide (CO2) is considered to be the main cause of
global warming, and efforts have been devoted to reduce its emissions on a global scale. On the other hand, carbon monoxide (CO),which is obtained by hydrogenation of CO2, is a useful chemical
raw material for liquid hydrocarbons such as alcohol, gasoline, jetfuel, etc. The reaction of CO2 with hydrogen (H2) to obtain CO (reverse water-gas shift reaction) conventionally requires a high temperature of 500℃ or higher. Yamashita Laboratory has discoveredthat CO can be obtained efficiently and selectively from CO2 andH2 at around 140℃ using a catalyst composed of molybdenum oxide coupled with platinum (Pt) nanoparticles. Furthermore, the reaction rate significantly increased when the catalyst was irradiatedwith light.

▍ Significance of the research and Future perspective
山下 弘巳

This catalyst has the basic features essential for practical use,such as simple preparation, easy separation of the catalyst, andlow temperatures required for operation where waste heat canbe used. Furthermore, the reaction rate is significantly increased
under the irradiation of light. This technology is expected to be aclean catalytic technology for converting CO2 into industrially useful substances with low energy consumptions.

▍ Background & Results
CO2 is considered to be a major contributor to global warming,and efforts have been devoted to reduce its emissions on a global
scale. Japanese government declared an intention to achieve zero
emissions of greenhouse gases including CO2 by 2050. To achieve
this goal, development of technologies to recover CO2 as a carbon
resource and utilize it as a useful material (CO2 capture and utilization technology) has been required. If CO2 can be efficiently converted to CO, it will be possible to produce useful substances while
reducing CO2 emissions, thereby contributing to the problems ofglobal warming and depletion of fossil resources. However, thereaction to produce CO by reacting CO2 with H2 (reverse water-gas
shift reaction, equation:（CO2 + H2 = CO + H2O）conventionallyrequires a high temperature of 500℃ or higher, and only a low reaction rate can be obtained at low temperatures due to equilibrium
constraints.
Our research group has succeeded in selectively producing
CO from CO2 using a catalyst composed of molybdenum oxide
coupled with platinum (Pt) nanoparticles, allowing the reaction toproceed efficiently and selectively at approximately 140℃, a much
lower temperature than that reported earlier. Interestingly, we also
found that the reaction rate is significantly improved when the catalyst is irradiated with light. In particular, the catalyst consisting of
Pt nanoparticles immobilized on nano-sheet molybdenum oxidewith a thickness of about 40 nm showed a CO production rate 1.5
times higher than that using particulate molybdenum oxide, andCO was produced at a reaction rate of 1.2 mmol/g/h under visible
light irradiation. The key to achieve this result are (i) the formationof oxygen defects as active sites by combining molybdenum oxidewith Pt nanoparticles, and (ii) the change of the optical property ofthe molybdenum oxide which originates from surface plasmon resonance.

Figure 1 Catalyst development for energy-saving CO2 recycling

Figure 2 Results of CO2 hydrogenation using molybdenum oxide-supported Pt
nanoparticle catalysts

Figure 3 Scanning electron microscope (SEM) image and transmission electron
microscope (TEM) images of molybdenum oxide-supported Pt nanoparticle catalysts

P a t e n t Japanese Patent Application No. 2020-093711
Ge, Hao; Kuwahara, Yasutaka; Yamashita, Hiromi et al. Plasmon-induced Catalytic CO2 Hydrogenation by a Nano-sheet Pt/HxMoO3-y Hybrid with AbundantSurface Oxygen Vacancies. Journal of Materials Chemistry A. 2021; 9 (24): 13898-13907. doi: 10.1039/d1ta02277f
Tr e a t i s e
Kuwahara, Yasutaka; Mihogi, Takashi; Yamashita, Hiromi et al. A Quasi-stable Molybdenum Sub-oxide with Abundant Oxygen Vacancies that Promotes
CO2 Hydrogenation to Methanol. Chemical Science. 2021; 12 (29): 9902-9915. doi: 10.1039/d1sc02550c
UR
L https://resou.osaka-u.ac.jp/ja/research/2021/20210526_2
K e y w o r d CO2 capture and utilization, CO2 reutilization, molybdenum oxide, surface plasmon resonance