Spectroscopic evidence of the simultaneous participation of rhodium carbonyls and surface formate species during the CO2 methanation catalyzed by ZrO2-supported Rh

Combined In Situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Kinetic Studies on CO2 Methanation Reaction over Ni/Al2O3

“…The first one starts with the activation of CO 2 to generate *CO species followed by further hydrogenation into CH 4 (known as the “CO route”), while the second one involves the consecutive hydrogenation of adsorbed CO 2 to directly produce CH 4 without any *CO species (known as the “non-CO route”) . For the CO route, activation of CO 2 proceeds via direct dissociation of CO 2 (redox mechanism) or the transformation and decomposition of carbon-containing intermediates (e.g., formate, carbonyl, and carboxylate) in the presence of H 2 /*H (an associative mechanism). − …”

Insights into the Zn Promoter for Improvement of Ni/SiO2 Catalysts Prepared by the Ammonia Evaporation Method toward CO2 Methanation

“…Figure a,b shows reaction activity with methane peaks at 3014 cm –1 at 250–450 °C. The bands at 3737 and 3601 cm –1 are attributed to OH species. , The bands at 2850 and 1572 cm –1 are assigned to formate, and 2015 and 1830 cm –1 are assigned to adsorbed CO odes. , The band at 1056 cm –1 can be ascribed to bicarbonate species. , As shown in Figure a, the carbonyl species could be observed on 2062 cm –1 at 150–200 °C in the Ni/SiO 2 catalyst, , while the 80Ni-Zn/SiO 2 catalyst did not, which suggests that the Ni metal sintering was prevented during methanation reaction because of the Zn promoter. The reaction intermediates involved in the reaction of these two catalysts are identical, suggesting that the addition of a small amount of Zn promoter has no effect on the CO 2 methanation reaction pathway.…”

“…47,48 The band at 1056 cm −1 can be ascribed to bicarbonate species. 45,49 As shown in Figure 9a, the carbonyl species could be observed on 2062 cm −1 at 150−200 °C in the Ni/SiO 2 catalyst, 50,51 while the 80Ni-Zn/SiO 2 catalyst did not, which suggests that the Ni metal sintering was prevented during methanation reaction because of the Zn promoter. The reaction intermediates involved in the reaction of these two catalysts are identical, suggesting that the addition of a small amount of Zn promoter has no effect on the CO 2 methanation reaction pathway.…”

Addressing the CO2 challenge through thermocatalytic hydrogenation to carbon monoxide, methanol and methane

“…On zirconia, formate and carbonyl intermediates were detected by infrared spectroscopy with a simultaneous consumption of these two species, suggesting their participation in the reaction pathway. 274 Similarly, on ceria, these species were also observed in addition to carbonates adsorbate. 275 From the evolution of these adsorbed species with modification of temperature, the authors proposed a reaction pathway proceeding based on carbonyl intermediates.…”