Tailoring the active phase of CoO-based thin-film catalysts in order to tune selectivity in CO2 hydrogenation

• Published in: RSC advances 2024-05, Vol.14 (24), p.16758-16764
• Main Authors: Mohammadpour, Niloofar, Kierzkowska-Pawlak, Hanna, Balcerzak, Jacek, Tyczkowski, Jacek
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Catalysts; Chemistry; Cobalt; Cobalt oxides; Continuous flow; Continuously stirred tank reactors; Hydrogenation; Methanation; Photoelectrons; Plasma enhanced chemical vapor deposition; Shift reaction; Steel wire; Thin films; X ray photoelectron spectroscopy
• ISSN: 2046-2069
• DOI: 10.1039/d4ra02355b

In this study, we prepared CoO-based thin films deposited on Kanthal steel wire gauze meshes by plasma-enhanced chemical vapor deposition. X-ray photoelectron spectroscopy (XPS) analysis revealed a structure characterized by a combination of cobalt oxide and metallic cobalt embedded within a carbon matrix. Our primary objective was to gain insights into the roles of Co0 and CoO in CO2 hydrogenation reactions. To achieve this, the performance of the thin-film CoO-based catalyst with an initial atomic ratio of CoO/Co0 at 10.2 was compared with two series of the thin-film catalysts that underwent pre-reduction processes at 350 °C for durations of 30 and 60 minutes, resulting in atomic ratios of CoO/Co0 at 3.1 and 1.1, respectively. Subsequently, catalytic tests were conducted in a continuous flow stirred tank reactor operating at temperatures ranging from 250 °C to 400 °C. Our findings indicate that CoO plays a significant role in activating the CO2 methanation reaction which can be due to the high hydrogen coverage of CoO, while Co0 is the active phase in the reverse water–gas shift reaction. Results highlight the importance of oxidized cobalt for hydrogen adsorption and dissociation in CO2 hydrogenation for CH4 formation.