Metal–Support Interactions in CeO₂- and SiO₂-Supported Cobalt Catalysts: Effect of Support Morphology, Reducibility, and Interfacial Configuration

Abstract

With the increasing demand for highly efficient and durable catalysts, researchers have been doing extensive research to engineer the shape, size, and even phase (e.g., hcp or fcc Co) of individual catalyst nanoparticles, as well as the interface structure between the catalyst and support. In this work, cobalt oxides were deposited on ceria with rod-like morphology (CeO2NR) and cube-like morphology (CeO2NC) and silica with sphere-like morphology (SiO2NS) via a precipitation–deposition method to investigate the effects of support morphology, surface defects, support reducibility, and the metal–support interactions on redox and catalytic properties. XRD, Raman, XPS, BET, H2-TPR, O2-TPD, CO-TPD, TEM, and TPR/TPO cycling measurements have been mainly employed for catalysts characterization. Compared with CeO2NC and SiO2NS supports, as well as CeO2NC- and SiO2NS-supported cobalt catalysts, CeO2NR counterparts exhibited enhanced reducibility and CO oxidation performance at a lower temperature. Both the apparent activation energy and CO conversion demonstrated the following catalytic activity order: 10 wt % CoO x /CeO2NR > 10 wt % CoO x /CeO2NC > 10 wt % CoO x /SiO2NS. These results showed a strong support-dependent reducibility, CO oxidation, and redox cycling activity/stability of the as-prepared catalysts. Moreover, the significantly enhanced catalytic CO oxidation of the 10 wt % CoO x /CeO2NR catalyst indicated the vital role of CeO2NR support with rich surface oxygen vacancies, superior oxygen storage capacity and mobility, and excellent adsorption/desorption behavior of CO and O2 species.

Mechanism and regeneration of sulfur-poisoned Mn-promoted calcined NiAl hydrotalcite-like compounds for C3H6-SCR of NO

“…6), three main characteristic peaks are clearly observed over each sample, which locate at 200-400 C, 400-750 C and above 750 C, corresponding to the physically/chemically adsorbed oxygen O 2 (a), dissociated oxygen O 2À /O À at the vacancy sites (b), and bulk lattice oxygen (g), respectively. 28 We also quantied the oxygen desorption peaks (Table 2), which suggested Mn incorporation obviously enhanced all the oxygen desorption peaks, especially the peak b, implying positive effects for the mobility of the active oxygen species of these catalysts. Besides, the physically/chemically adsorbed oxygen O 2 (a) and dissociated oxygen O 2À /O À at the vacancy sites (b) are found to be the most abundant over the 5% MnNiAlO catalyst, which reect more active oxygen species.…”

Mesoporous SiO2‐Encapsulated Nano‐Co3O4 Catalyst for Efficient CO Oxidation

“…Consequently, more characterizations are required to be carried out to further investigate the active oxygen species over the catalysts, which will be discussed in the following parts. CO-TPD experiments were conducted to provide information about the surface oxygen species as well as the strength of chemisorption, [41] with the evolution curves shown in Figure 6. In general, CO adsorbates react with the oxygen species in the catalyst and desorb in the form of CO 2 during the heating process in N 2 flow.…”

“…In general, CO adsorbates react with the oxygen species in the catalyst and desorb in the form of CO 2 during the heating process in N 2 flow. [41,42] The desorption peak below 170°C represents the CO 2 formed by the adsorbed CO reacting with the surface adsorbed and lattice oxygen species. The peak area reflects the amount of surface oxygen and is considered to correlate to the low-temperature CO oxidation activity.…”

CoaSmbOx Catalyst with Excellent Catalytic Performance for NH3 Decomposition

“…Usually, the surface of the inert oxide does not participate in the reaction. [ 29‐31 ] In this case, the Sm 2 O 3 is only considered a supporting role and often had poor catalytic performance. [ 32‐33 ] To explore the role of the inert supports in the catalytic reaction, we use Sm 2 O 3 to support a cobalt‐based catalyst for ammonia decomposition.…”