Synergy of Oxygen Vacancies and Ni⁰ Species to Promote the Stability of a Ni/ZrO₂ Catalyst for Dry Reforming of Methane at Low Temperatures

Abstract

Low-temperature dry reforming of methane (DRM) can avoid the sintering of nickel and reduce the cost of the process. However, inefficient activation of CO 2 and oxidization of Ni 0 hamper the catalytic performance of Ni-based catalysts at low temperatures. Herein, a Ni/ZrO 2 catalyst was prepared and used in the DRM reaction, which exhibited stable activity at low temperatures (400, 320 and 300 °C) for 10 h, with CH 4 and CO 2 turnover frequencies of 0.26 and 0.18 s −1 at 320 °C, respectively. The presence of Ni 0 species and oxygen vacancies promotes the activation of CO 2 at 300 °C, proved by CO 2 temperature-programmed oxidation (CO 2 -TPO). Combined with O 2 temperature-programmed decomposition (O 2 -TPD), C 18 O 2 -DRM, in situ X-ray photoelectron spectroscopy (XPS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results, after CH 4 decomposition on the Ni 0 site, the resultant C would react with nearby surface oxygen species and lattice oxygen species of ZrO 2 , forming CO and an oxygen vacancy. The oxygen vacancy nearby Ni 0 species with more electron transfer would promote the activation of CO 2 . This work highlights the importance of CO 2 activation and emphasizes the key role of the synergistic effect between Ni 0 species and the oxygen vacancy in enhancing the stability of catalysts over low-temperature DRM reactions.

Ce-Driven Ce-MnOx/Na2WO4/SiO2 Composite Catalysts for Low-Temperature Oxidative Coupling of Methane

“…In contrast, the 3Ce-MnO x catalyst displays several oxygen desorption peaks at 250–500 °C and above 600 °C. The peaks in the temperature range of 250–500 °C could be attributable to chemically adsorbed oxygen , and high area ratio of chemisorbed oxygen desorption peaks were also observed on catalysts with different Ce loadings (Figure S7 and Table S3), which may be due to the addition of Ce-induced oxygen vacancies in the catalysts, resulting in a higher surface chemisorbed oxygen content. Two types of adsorption peaks are associated with surface lattice oxygen (red peak) and bulk lattice oxygen (blue peak) above 600 °C, and the former is conducive to C–H bond activation of CH 4 and C 2 product selectivity .…”

Boosting CO2 Electroreduction to Multi‐carbon Products via Oxygen‐rich Vacancies and Ce4+−O2−−Cu+ Structure in Cu/CeO2 for Stabilizing Cu+

“…Previous studies have shown that the more oxygen vacancies introduced in CeO 2 samples with different Cu contents, the higher the CO 2 adsorption amount and the greater the adsorption capacity of the resulting intermediates, which can lead to excellent C 2 + selectivity under the synergistic effect of Cu 0 and Cu + active sites to promote CÀ C coupling. [28,51,52] In short, with the change in Cu content, the oxygen vacancy content changed, significantly affecting the CO 2 adsorption amount and the adsorption capacity of intermediates on the catalyst surface, resulting in the difference in CO 2 reduction activity in this series of samples. The electrochemical active surface area (ECSA) and electrochemical impedance spectroscopy (EIS) of the catalyst were investigated to reveal the reason for the high catalytic performance of the Cu 9.77 /CeO 2 catalyst in CO 2 RR.…”

Engineering a Nickel–Oxygen Vacancy Interface for Enhanced Dry Reforming of Methane: A Promoted Effect of CeO2 Introduction into Ni/MgO

“…As shown in Figure a,b, the adsorption configuration of CO 2 is somewhat different for these two catalysts. On the Ni/MgO catalyst, CO 2 molecules have been found to adsorb as carbonate and bicarbonate species. , It is observed that the strength of the adsorption peaks gradually decreases with increasing temperature until they practically vanish. Conversely, on the Ni/MgCe 0.12 O x catalyst, CO 2 is primarily observed to adsorb in the bicarbonate configuration, with minimal changes in the observed adsorption peak intensity with increased temperature.…”