Supported Molybdenum Carbide Nanoparticles as an Excellent Catalyst for CO₂ Hydrogenation

Abstract

Experiments under controlled conditions show that MoC x nanoclusters supported on an inert Au(111) support are efficient catalysts for CO2 conversion, although with a prominent role of stoichiometry. In particular, C-deficient nanoparticles directly dissociate CO2 and rapidly become deactivated. On the contrary, nearly stoichiometric nanoparticles reversibly adsorb/desorb CO2 and, after exposure to hydrogen, CO2 converts predominantly to CO with a significant amount of methanol and no methane or other alkanes as reaction products. The apparent activation energy for this process (14 kcal/mol) is smaller than that corresponding to bulk δ-MoC (17 kcal/mol) or a Cu(111) benchmark system (25 kcal/mol). This trend reflects the superior ability of MoC1.1/Au­(111) to bind and dissociate CO2. Model calculations carried out in the framework of density functional theory provide insights into the underlying mechanism suggesting that CO2 hydrogenation on the hydrogen-covered stoichiometric MoC x nanoparticles supported on Au(111) proceeds mostly under an Eley–Rideal mechanism. The influence of the Au(111) is also analyzed and proven to have a role on the final reaction energy but almost no effect on the activation energy and transition state structure of the analyzed reaction pathways.

Multiple CO2reduction mediated by heteronuclear metal carbide cluster anions RhTaC2−

“…Transition-metal carbides are appealing supports for the dispersion of noble metals, and related catalysts exhibit extraordinary reactivity in many reactions, including CO 2 catalytic conversion. 57–61 The substantial importance of transition-metal carbides was highlighted to modify the electronic property of precious metals and then the activity of the catalysts in CO 2 adsorption and activation can be tuned. Transition-metal carbides can also act as co-catalysts to drive the reactions 10 and some of them bind CO 2 strongly and can then induce the cleavage of C–O bonds.…”

Effect of nanostructuring on the interaction of CO2with molybdenum carbide nanoparticles

“…Very recently, it has been shown that this pitfall can be overcome by making use of MoC y nanoparticles, which, depending on the system size and Mo/C atomic ratio, can transform CO 2 into oxygenates and light alkanes. 15,16 Experiments carried out for C-rich MoC 1.1 nanoparticles supported on Au(111) indicated that these new systems are able to dissociate and store significant amounts of hydrogen 17 and to catalyze the CO 2 hydrogenation. 15 Exposing these hydrogenated nanoparticles to CO 2 led to CO with a significant amount of methanol but without producing methane or other alkanes.…”

“…15 Exposing these hydrogenated nanoparticles to CO 2 led to CO with a significant amount of methanol but without producing methane or other alkanes. 16 Interestingly, these MoC 1.1 / Au(111) systems are also able to dissociate methane at room temperature. 18 The experiments also evidenced the major role played by the Mo/C atomic ratio, since the C-deficient nanoparticles were very active towards CO 2 but had problems of stability and selectivity, whereas the nearly stoichiometric ones were active, selective and stable.…”

Mo2C as Pre-Catalyst for the C-H Allylic Oxygenation of Alkenes and Terpenoids in the Presence of H2O2

“…Furthermore, under heterogeneous conditions, supported molybdenum carbides or nitrides (i.e., K-Mo 2 C/γ-Al 2 O 3 ) have been found to exhibit high activity and selectivity towards CO or methane production, even at large scale (ca. 1 kg catalyst), with the C/Mo ratio in their structure [29][30][31] (Scheme 1A) playing an important role. In this context, Mo 2 C was used as an efficient catalyst for the selective transfer hydrogenation process of nitroarenes into the corresponding anilines in the presence of hydrazine [32].…”