Effect of Small Molecular Organic Acids on the Structure and Catalytic Performance of Sol–Gel Prepared Cobalt Cerium Oxides towards Toluene Combustion

Abstract

Cobalt cerium oxide catalysts with small molecular organic acids (SOAs) as chelating agents were prepared via the sol–gel method and investigated for the complete oxidation of toluene. Four kinds of natural SOAs, i.e. malic acid (MA), citric acid (CA), glycolic acid (GA), and tartaric acid (TA), were selected. The effect of organic acids on the composition, structure, morphology and catalytic performance of metal oxides is discussed in details. The cobalt cerium oxides catalysts were characterized by various techniques, including TG–DSC, XRD, SEM–EDS, N2–adsorption and desorption, XPS, and H2–TPR analyses. The results show that the nature of organic acids influenced the hydrolysis, condensation and calcination processes, as well as strongly affected the textural and physicochemical properties of the metal oxides synthesized. The best catalytic activity was obtained with the CoCe–MA catalyst, and the toluene conversion reached 90% at 242 °C. This outstanding catalytic activity could be related to its textural, redox properties and unique surface compositions and oxidation states. In addition, the CoCe–MA catalyst also showed excellent stability in long–time activity test.

Cobalt-Ceria Binary Oxide Nanojunctions for Aqueous-Phase Aerobic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid: The Role of Interfaces

“…It might be the reason why the smaller size of Co 3 O 4 can be found over CoCe-MA than that on CoCe-CA. A similar phenomenon was found in the literature . Therefore, the smallest size of Co 3 O 4 and CeO 2 crystals in CoCe-MA nanojunctions was obtained after the calcination of the gel formed during the sol–gel process using malic acid as the complexing agent.…”

“…A similar phenomenon was found in the literature. 43 Therefore, the smallest size of Co 3 O 4 and CeO 2 crystals in CoCe-MA nanojunctions was obtained after the calcination of the gel formed during the sol−gel process using malic acid as the complexing agent. HRTEM observations were applied to illustrate the differences in the formation of interfaces in CoCe binary oxide nanojunctions, and the HRTEM images are shown in Figure 2.…”

Highly Active Transition Metal-Promoted CuCeMgAlO Mixed Oxide Catalysts Obtained from Multicationic LDH Precursors for the Total Oxidation of Methane

“…Figure 7 shows the photoelectron profiles of Co 2p region for the Co(x)CuCeMgAlO mixed oxides, while in Table 4 are presented the surface concentrations of cobalt. The photoelectron spectra were deconvoluted into two spin-orbit doublets corresponding to Co 3+ and Co 2+ species, respectively, and two shake-up peaks [44]. Thus, the Co 2p 3/2 component at 780.0 eV and a 2p 3/2 -2p 1/2 splitting of ca.…”

Editorial Catalysts: Catalysis for the Removal of Gas-Phase Pollutants

“…Cobalt cerium oxide catalysts prepared using the sol-gel method can be also used for toluene combustion at low temperatures, as described by Chen et al [6]. They studied the influence of the addition of different organic acids during catalyst preparation on the composition, structure, morphology, and catalytic performance of the metal oxides that were prepared.…”