http://ms.sit.edu.cn/picture/article/120/cc/09/bfaa57df4a72a85b5be6a43a00b9/6174eb71-4f3c-408c-b04a-b4270adcb4fd.pdf

Glycine–nitrate combustion synthesis of CuO–ZnO–ZrO2 catalysts for methanol synthesis from CO2 hydrogenation

Pure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization

A series of iron-based La1−xFeO3−δ perovskites (with x = 0, 0.1, 0.2, 0.3 and 0.4) was prepared by the so-called self-combustion method using glycine as an ignition promoter. The chemical, structural and surface properties of these mixed oxides were thoroughly characterized before the determination of their activity in the total oxidation of methane. The catalytic data indicated a strong dependence of the methane conversion towards the catalyst elemental composition. A progressive Fe2O3 enrichment of the perovskite surface was clearly evidenced by XPS characterization when decreasing the lanthanum content of the solid. Such additional undesirable surface iron oxide induced an inhibiting effect on the catalytic activity. As a result, while the La1−xFeO3−δ (x = 0, 0.1, 0.2, 0.3, 0.4) perovskites presented moderated performances in methane total oxidation, the most efficient lanthanum iron-based perovskite is the stoichiometric LaFeO3 mixed-oxide that exhibits the most adapted surface and global composition, resulting in a CH4 conversion of 86% at 873 K.

Influence of lanthanum stoichiometry in La1−xFeO3−δ perovskites on their structure and catalytic performance in CH4 total oxidation

Combustion synthesis and characterization of nanocrystalline LaAlO3 powders

MWO4 (M=Ca, Sr and Ba) scheelite ceramics were studied in terms of their syntheses, sintering, solubility in water, and dielectric response after storing them in dry and moist atmospheres. Of the studied scheelites, the CaWO4 possessed the most promising dielectric properties (ɛ=10.9, Q × f=105 600 GHz), which were stable under the influence of humidity. BaWO4 and SrWO4 exhibited ɛ=9.0 and Q × f values of 32 200 and 62 600 GHz, respectively. The most detrimental effect of the moisture was observed for SrWO4. A sodium impurity present in the SrCO3 reagent (0.35 wt%), which was used for the synthesis of the SrWO4, was found to lower the sintering temperature, enhance the grain growth, and change the other properties of the ceramics, such as humidity susceptibility and solubility in water. The evident tendency of the ceramics to attract water and the increased dissolution of tungstate were observed for all MWO4 scheelite ceramics, which were sintered with the help of Na2CO3 or Li2CO3 (0.5 wt%) sintering aids. The results of the present study suggest that the physical and chemical properties of the ceramics should be carefully considered in the case of using of alkaline-containing sintering aids.

Hong-Tao Yu

Papers

Combustion synthesis and characterization of nanocrystalline LaAlO3 powders

Effect of BaWO4 on microstructure microwave dielectric properties of Ba(Mg1/3Nb2/3)O3

New microwave dielectric ceramics with near-zero τf in the Ba(Mg1/3Nb2/3)O3-Ba(Ni1/3Nb2/3)O3 system