Magnesium-Modified Co3O4 Catalyst with Remarkable Performance for Toluene Low Temperature Deep Oxidation

Toluene Oxidation: CO2 vs Benzaldehyde: Current Status and Future Perspectives

Toluene is a common and significant volatile organic compound (VOC). Although it finds extensive application in various industrial processes (chemical manufacturing, paint and adhesive production, and as a solvent), it creates a huge environmental impact when emitted freely into the atmosphere. Two solutions were found to mitigate the emission of this pollutant: the total oxidation to CO2 and H2O and the selective oxidation into benzaldehyde. This review discusses the two main alternatives for tackling this problem: converting the toluene into carbon dioxide by total oxidation or into benzaldehyde by selective oxidation. It presents new catalytic advances, new trends, and the advantages and disadvantages of both methods.

A Hands-on Guide to the Synthesis of High-Purity and High-Surface-Area Magnesium Oxide

In this study, magnesium nitrate, chloride or sulphate were used in the synthesis of Mg(OH)2, the precursor of MgO. It was found that the counter ion strongly influences the purity of the Mg(OH)2, as well as the specific surface area of the obtained MgO. The latter is also strongly influenced by the calcination temperature. The choice of the precipitating agent can lead to the introduction of K+ or Na+ ions and hence NH3 (aq) is the best choice. A multistep precipitation procedure of Mg(OH)2 was proposed to lower the concentration of typical impurities (Fe, Ni and Mn) found in commercial p.a. purity Mg(NO3)2. The effect of the number of portions of water used for washing of Mg(OH)2 on the purity of the final product has also been investigated in detail. The stages of formation of grains of Mg(OH)2 and their subsequent thermal decomposition was described together with determination of the introduction of new impurities into the material. Large scale (1500 g) preparation of Mg(OH)2 with an improved purity was performed and described. Therefore, this study explains what measures should be taken to obtain pure magnesia catalysts and is a valuable resource for catalytic research in which magnesia is used.

Magnesium Cobaltite Embedded in Corncob-Derived Nitrogen-Doped Carbon as a Cathode Catalyst for Power Generation in Microbial Fuel Cells

Microbial fuel cells (MFCs) have drawn attention among renewable energy devices. High capital cost, poor durability, and slow oxygen reduction reaction (ORR) kinetics are the major hindrances in the commercialization of the technology. In this work, an environmentally benign approach is followed to synthesize a composite of magnesium cobaltite (MgCo₂O₄) embedded in nitrogen-doped carbon to optimize the performance of MFCs. Detailed characterization confirms the formation of MgCo₂O₄ nanostructures in the catalyst treated at 700 °C. Electrochemical studies suggest the superior performance of the MgCo₂O₄/NC-700 catalyst with a peak reduction current of -0.068 mA and a charge transfer resistance (R_ct) of 40.5 Ω. The performance of the air cathodes is evaluated using activated sludge as inoculum in the anode chamber in single-chamber MFCs. The power output of MFC with MgCo₂O₄/NC-700 as an air cathode reaching 873.81 mW m^-2 is 59.56 and 216.05% higher than those of MFCs with Pt/C (547.65 mW m^-2) and Co/NC-700 (276.48 mW m^-2) cathodes, respectively. These findings suggest that substituting magnesium in transition metal-nitrogen-carbon composites could help realize long-term application as air cathodes for power generation and wastewater treatment in MFCs.