Synthesis of PbMoO4 Nanoparticles Using a Facile Surfactant-Assisted Microwave Process and Their Photocatalytic Activity.

Lead molybdate (PbMoO4) materials were successfully synthesized using a facile surfactant-assisted microwave process and characterized by XRD, Raman, PL, BET and DRS. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. The XRD and Raman results revealed the successful synthesis of 42­69 nm, well-crystallized PbMoO4 crystals with a facile surfactant-assisted microwave process. The PbMoO4 catalysts prepared using microwave process enhanced the photocatalytic activity compared to PbMoO4 catalyst prepared by hydrothermal method. The PbMoO4 catalyst prepared at 100 °C showed the highest photocatalytic activity. The PL peak was appeared at about 540 nm for all catalysts and the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of Rhodamine B.

Catalytic Oxidation of Benzene Over LaCoO3 Perovskite-Type Oxides Prepared Using Microwave Process.

LaCoO3 perovskite type oxides were successfully prepared using microwave-assisted method, characterized by TG/DTA, XRD, XPS and H2-TPR and their catalytic activities for combustion of benzene were determined. Almost of catalyst showed perovskite crystalline phase and 13-84 nm particle size. LaCoO3 catalysts prepared by microwave-assisted method showed the highest activity and the conversion reached almost 100% at 360 degrees C. In the LaCoO3-type catalyst, the partial substitution of Sr into site A enhanced the catalytic activity on the combustion of benzene. The higher amount of the chemisorbed oxygen was, the better the performance of the combustion catalyst. The catalytic activity of perovskite-type oxides showed a good relationship with the results of H2-TPR and XPS measurement.

Synthesis of PbMoO4 nanoparticles by microwave-assisted hydrothermal process and their photocatalytic activity.

Lead molybdate (PbMoO4) was successfully synthesized using a microwave-assisted method and characterized by XRD, Raman spectroscopy, SEM, PL and DRS. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamin B under UV-light irradiation. The XRD and Raman results revealed the successful synthesis of 42-52 nm, well-crystallized PbMoO4 crystals with the microwave-assisted hydrothermal method. The PbMoO4 catalysts prepared using the microwave-assisted process enhanced the photocatalytic activity compared to that prepared by hydrothermal method and the catalysts prepared at a solution pH = 11 and temperature of 105 degrees C showed the highest photocatalytic activity. The PL peaks appeared at about 540 nm for all catalysts and the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of Rhodamin B.

Catalytic combustion of benzene over nanosized LaMnO3 perovskite oxides.

In this study, LaMnO3 perovskite type oxides were successfully prepared using the malic acid method. The oxides were characterized by TG/DTA, XRD, XPS, TEM and H2-TPR and their catalytic activities for the combustion of benzene were determined. Almost all of the catalysts showed perovskite crystalline phase and had a particle size of 15-60 nm. The LaMnO3 catalysts prepared with more than 1.0 mol of malic acid showed the highest activity and the conversion reached almost 100% at 310 degrees C. The catalysts were modified to enhance the activity by substituting the metal at the A or B site of the perovskite oxides. In the LaMnO3-type catalyst, the partial substitution of Sr into site A enhanced the catalytic activity during benzene combustion. In addition, the partial substitution of Co into site B also increased the catalytic activity and the catalytic activity was in the following order: Co > Cu > Fe in the LaMn1_xBxO3(B = Co, Fe, Cu) type catalysts.

Synthesis of TiO2 supported on SBA-15 using different method and their photocatalytic activity.

SBA-15 mesoporous materials were successfully prepared by the conventional hydrothermal method and TiO2 nanoparticles were supported on them using different loading methods. The synthesized materials were characterized and their activity as photocatalysts for the decomposition of methylene blue was evaluated. The loading of titanium dioxide on the framework of SBA-15 makes the pore diameter and pore volume decrease compared to that of SBA-15. The chelating method causes the support to have a much better dispersion capacity for TiO2 particles as compared to the other two methods. The TiO2 supported by chelating method showed the highest photocatalytic activity among the photocatalysts prepared by different method.

Synthesis of TiO2 supported on SBA-15 using chelating method and their photocatalytic decomposition of methylene blue.

SBA-15 mesoporous materials were successfully prepared by the conventional hydrothermal method and used as the support for TiO2 loaded SBA-15 photocatalysts. The synthesized materials were characterized by XRD, PL, FT-IR, BET and TEM. We also examined the activity of these materials as photocatalysts for the decomposition of methylene blue. The loading of titanium dioxide on the framework of SBA-15 makes the pore diameter and the pore volume decrease and decreases the surface area compared to that of SBA-15. For the TiO2 loaded SBA-15 photocatalysts, the IR absorption at approximately 960 cm(-1) is commonly accepted as the characteristic vibration of the Ti-O-Si bond. The PL peaks appears at about 410 nm at a loading ratio of less than 5% but moves to 430 nm at higher loading ratios. It was also shown that the excitonic PL signal is proportional to the photocatalytic activity for the decomposition of methylene blue. The photocatalytic activity increases with increasing TiO2 loading ratio, shows a maximum value at 7% TiO2/SBA-15, and then decreases at 10% TiO2/SBA-15.

Microwave-accelerated energy-efficient esterification of free fatty acid with a heterogeneous catalyst.

This paper shows energy-efficiency of microwave-accelerated esterification of free fatty acid with a heterogeneous catalyst by net microwave power measurement. In the reaction condition of 5 wt% sulfated zirconia and 1:20 M ratio of oil to methanol at 60°C and atmospheric pressure, more than 90% conversion of the esterification was achieved in 20 min by microwave heating, while it took about 130 min by conventional heating. Electric energy consumption for the microwave heating in this accelerated esterification was only 67% of estimated minimum heat energy demand because of significantly reduced reaction time.

Formation of TiO2 nanoparticles in water-in-CO2 microemulsions.

Titanium dioxide nanoparticles can be produced by the controlled hydrolysis of titanium tetraisopropoxide in water-in-CO2 (w/c) microemulsions stabilized with the surfactants ammonium carboxylate perfluoropolyether (PFPE-NH4) and poly(dimethyl amino ethyl methacrylate-block-1H,1H,2H,2H-perfluorooctyl methacrylate) (PDMAEMA-b-PFOMA); the greater control of hydrolysis and particle growth with PDMAEMA-b-PFOMA is consistent with the differences in the stabilities and interactions for these two microemulsions.