Insight into the pH effect on the oxygen species and Mn chemical valence of Co–Mn catalysts for total toluene oxidation

Abstract

Mn-based metal oxides have shown promising performance in catalytic oxidation of toluene since the mixed valences of Mn3+ and Mn4+ on the surface. Herein, a series of Co-Mn catalysts were...

Copper and iron co-doping effects on the structure, optical energy band gap, and catalytic behaviour of Co3O4 nanocrystals towards low-temperature total oxidation of toluene

“…4,5 Presently, two varieties of catalysts have been established for the total conversion of toluene,, namely supported noble metals (Ag, Au, Pt and Pd) [6][7][8][9] and metal oxides. [10][11][12][13][14][15] Particularly, Transition metal oxides (TMOs) especially possesses the advantages of availability, low cost, high thermal stability, considerable reducibility, strong resistance to poisons and promising catalytic performance. [16][17][18] Therefore, TMOs have received much attention in the total abatement of VOCs.…”

“…To date, several binary metal-doped (Mn, Cu, Ni, and Fe) Co3O4 thin films and nanocrystals powder were prepared and successfully tested as catalysts. 13,15,22 Among of TMOs-based catalysts, Co-Cu and Co-Fe oxide catalysts have exhibits promising performance in the elimination of VOCs. In fact, by introducing different types of transition metals (TMs) into the pure TMOs lattice, the redox behaviour and chemical activity of the obtained mixed-TMOs can be modify due to many factors.…”

“…25 Although doping has a significant impact on the catalytic behavior of individual oxides, research has mainly focused on binary oxides, and there have been only a few studies investigating catalytic oxidation with ternary or trimetallic oxidesbased TMs. 13,26 However, it is not a priori clear what type and number of metals is required to enhance single-TMOs catalytic activity and the lattice stability at high temperature. Ternary oxides are generally used as electrocatalysts with a wide variety of critical physicochemical properties, excellent stability for several applications, such materials can be also be highly active catalysts and display an exceptional activity compared to single and binary oxides.…”

General Route to Colloidally Stable, Low-Dispersity Manganese-Based Ternary Spinel Oxide Nanocrystals

“…To the best of our knowledge, the current research of ternary Mn spinels, however, has been unable to develop synthetic methods to produce small, colloidally stable, low-dispersity nanocrystals. Of particular interest is the CMO family of spinels, known for their superior electrocatalytic and supercapacitor performance. ,,− ,,,, Previous work using hydrothermal/solvothermal, − solid-state, ,, co-precipitation, ,, or solvent-assisted ,, methods to generate CMO spinels has resulted in large, ,,,,, aggregated ,,,, nanocrystals with poor size control. Additionally, methods like solvothermal and hydrothermal reactions make optimization and scaling more difficult because of the need for a pressurized vessel, which leads to the inability to take reaction aliquots, thus restricting the determination of the onset of Ostwald ripening. − …”

Investigation of the effect of thermal annealing of Ni-cobaltite nanoparticles on their structure, electronic properties and performance as catalysts for the total oxidation of dimethyl ether

“…Two types of catalyst have been developed for the lowtemperature oxidation, namely supported precious metals (Ag, Au, Pt and Pd) [6][7][8][9] and mixed metal oxides. [10][11][12][13][14] Several studies on the total oxidation of DME over Au, Pt, Pd, Rh, and Ru catalysts supported on different oxides including Al 2 O 3 , ZrO 2 , TiO 2 and CeO 2 have been performed 6,[15][16][17][18][19] and the results revealed that Ru and Pt catalysts supported on Al 2 O 4 exhibit total oxidation of DME to CO 2 and H 2 O within the temperature range from 400 to 600 °C, which is not satisfactory for low-temperature activity. In addition, the disadvantages of noble metals are their higher cost, poor availability, poisoning tendency and unsuitable and expensive investment for industrial applications.…”