A series of nanosized gold supported on CeO 2 , MnO 2 , and MnO 2 -CeO 2 composite oxides have been prepared by a deposition-precipitation (DP) method and the effects of Mn/Ce atomic ratio on Au/MnO 2 -CeO 2 catalysts and calcination temperature after loading gold for preferential oxidation of CO (PROX) in H 2 stream have been investigated using a fixed-bed continuous-flow reactor at various temperatures. The catalysts were characterized by XRD, nitrogen sorption, TEM, and XPS. XRD analysis confirms the phase purity of CeO 2 and MnO 2 phases and the fine dispersion of Au on Au/MnO 2 -CeO 2 catalysts. XPS analysis shows the formation of MnO 2 -CeO 2 solid phase with manganese loading on ceria support accompanied by an increase in Ce 4+ surface concentration. ICP-AES demonstrates the increase in gold loading with manganese addition by DP method. A synergistic catalytic effect on conversion and selectivity was observed in the case of Au/MnO 2 -CeO 2 catalysts, due to the coexistence of metallic and nonmetallic gold species within nano gold particle and the minor presence of Ce 3+ species.

Amorphous nanosized NiB catalysts have been reported to be a good catalyst for the liquid-phase hydrogenation of chloronitrobenzene. This study was conducted to investigate the effect of lanthanum on the catalytic properties of the NiB catalyst in the liquid-phase hydrogenation of p-chloronitrobenzene (p-CNB). The lanthanum-promoted NiB catalyst was prepared via the liquid-phase reduction of nickel cations by borohydride. The atomic ratio of boron to nickel in the mother solution was B/Ni = 3:1. The catalysts were characterized by N2 sorption, powder X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Liquid-phase hydrogenation of p-CNB was performed in a well-stirred, high-pressure batch reactor system. The catalysts prepared in this study had nanosized particles. La-NiB was much more active than NiB and the Raney nickel catalyst. The selectivity of the main product (p-chloroaniline, p-CAN) was >99% on La-NiB catalysts. However, excess amounts of lanthanum caused a decrease in the activity. The effect of the lanthanum promoter can be attributed to the electronic modification of nickel by lanthanum.

Barium titanate fine particles were prepared by hydrothermal synthesis. The synthesis was preformed at a temperature between 75 and 180 °C and for 10 min to 96 h. The reactions were carried out in a strong alkaline solution. Ba(OH)2·8H2O was used as the Ba-precursor material. Various Ti precursors were used to investigate their effects on the properties of BaTiO3. The BaTiO3 powders were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, nitrogen sorption, and differential scanning calorimetry. XRD showed that the as-synthesized BaTiO3 powders have the BaTiO3 structure. The particle size of the Ti precursor has a strong influence on the size and morphology of barium titanate. The particle size of BaTiO3 was the largest when synthesized at 120 °C for 24 h by using anatase TiO2 (Merck) precursor. The particle size was about 0.1 μm when using TiO2 (70% anatase and 30% rutile, Degussa P25) or Ti(OH)4 as the precursor. The BaTiO3 powder was a porous structure when using Ti(OH)4 as the precursor. In addition, the particle size and morphology were dependent on the synthesis temperature. At 85 °C, the morphology of the powder was small crystal and an agglomerate of clusters. At 180 °C, the morphology of the powder was large (∼130 nm), uniform, and nearly monodisperse particles. Extending the synthesis time has no significant influence on the size and morphology.

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