Structured Cerium-Manganese Catalysts Supported on Nickel Foam for Toluene Oxidation by Electric Internal Heating

Structured catalysts are widely used in catalytic oxidation of gaseous pollutants, hot catalysis is usually needed to assist the reaction in the catalytic process. Herein, a Ce-modified manganese oxide octahedral molecular sieves (Ce-OMS-2) structured catalyst supported on foam nickel was prepared through impregnation process. A systematically quantitative testing on the toluene catalytic oxidation effectiveness of this structured catalyst was conducted through catalyst evaluation device, combining a series of characterization methods, such as XRD and SEM, the structure-activity relationship was established. Assisted with electric internal heating and ozone oxidation environments, this structured catalyst exhibits excellent catalytic oxidation performance for oxidative decomposition of toluene even under high humidity conditions. The results showed that the ozone-coupled structured nickel foam catalyst increased the decomposition efficiency of toluene from 25 % (without catalyst and heating) to 55 % (with catalyst and without heating) and the electric internal heating can significantly improve the reactivity and moisture resistance of the structured nickel-foam catalyst, at 90 % RH and 40000 h-1, 50000 ppb O3 and 40 mg/m3 toluene was maintained 100 % catalytic efficiency. The high-efficiency non-precious metal-based electrothermal catalyst prepared herein is expected to have certain enlightenment for the purification of VOCs.

A novel hollow microsphere composite MnOx/PAA: effective catalyst for ozone decomposition at high humidity

Ozone air pollution poses a serious threat to human health and ecological environment. Manganese oxide (MnOx) is a popular material for ozone decomposition with excellent catalytic performance. However, the catalytic activity may be reduced under high-humidity conditions because of oxygen vacancy of MnOx from the water evaporation. In this paper, a new type of MnOx/poly(acrylic acid-co-divinylbenzene) (PAA) catalyst with MnOx supported on hollow PAA was successfully prepared, which greatly improved the ozone decomposition efficiency under high humidity. It was shown that when the acrylic acid (AA) content was more than 50%, the PAA polymer layer was hydrophilic and the ozone decomposition efficiency would keep high activity for both the low- and high-humidity conditions. The best performance of ozone decomposition was identified for the methanol reduction and AA content of 60%, in which the efficiencies reached 94.5% and 85% at 50% and 90% humidity levels, respectively. It is the synergetic effect of the hydrophilic PAA support and hollow structure that retains and improves the decomposition activity, which can absorb the water vapor molecules and increase the ozone retention time. Therefore, the hollow microsphere catalyst prepared in this paper has great potential in solving the problem of ozone air pollution.

The Synthesis and Characterisation of the High-Hardness Magnetic Material Mn2N0.86

High-quality P6₃22 Mn₂N_0.86 samples were synthesised using a high-pressure metathesis reaction, and the properties of the material were investigated. The measurements revealed that the Vickers hardness was 7.47 GPa, which is less than that predicted by commonly used theoretical models. At low air pressure, Mn₂N_0.86 and MnO coexist at 500 to 600 °C, and by excluding air, we succeeded in producing Mn₄N by heating Mn₂N_0.86 in nitrogen atmosphere; we carefully studied this process with thermogravimetry and differential scanning calorimetry (TG-DSC). This gives a hint that to control temperature, air pressure and gas concentration might be an effective way to prepare fine Mn-N-O catalysis. Magnetic measurements indicated that ferromagnetism and antiferromagnetism coexist within Mn₂N_0.86 at room temperature and that these magnetic properties are induced by nitrogen vacancies. Ab intio simulation was used to probe the nature of the magnetism in greater detail. The research contributes to the available data and the understanding of Mn₂N_0.86 and suggests ways to control the formation of materials based on Mn₂N_0.86.

Exploring an efficient manganese oxide catalyst for ozone decomposition and its deactivation induced by water vapor

A series of MnO_x catalysts supported by carbon spheres were prepared by calcining mixtures of manganese acetate and carbon spheres under a nitrogen atmosphere, and their performance for ozone decomposition under high humidity conditions (RH = 90%) was evaluated.

Understanding the crucial roles of catalyst properties in ethyl acetate and toluene oxidation over Pt catalysts

The catalytic activities of these Pt catalysts for ethyl acetate mainly depend on the oxygen vacancy density, whereas the synergistic catalysis of Pt⁰ species and oxygen vacancies play important roles in toluene oxidation.

High performance cobalt nanoparticle catalysts supported by carbon for ozone decomposition: the effects of the cobalt particle size and hydrophobic carbon support

Catalytic gaseous ozone decomposition under high humidity is not only an urgent need but also a significant challenge because of the low stability over the available catalysts.