Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

/pdf/dye-sensitized-solar-cells-50b0w2bhsr.pdf

Dye-Sensitized Solar Cells

The surface and materials science of tin oxide

Fuel processing for low-temperature and high-temperature fuel cells: Challenges, and opportunities for sustainable development in the 21st century

This review examines recent developments in the complete oxidation of methane at low temperature over noble metal based catalysts in patents and open literature. The abatement of natural gas vehicle (NGV) methane emissions is taken as one example among possible applications. The review develops current ideas about the properties of palladium and platinum catalysts supported on silica and alumina supports in the complete oxidation of methane under oxidising conditions, focusing on low-temperature reaction conditions. The influence of residual chloride ions on the catalytic activity, the kinetic aspects of the oxidation of methane over these catalysts, the nature of the active sites, the influence of metal particle size and reaction products on the activity, the observed changes in catalytic activity with reaction time and the effect of sulphur containing compounds are examined. The latest studies concerned with improved palladium and platinum supported catalysts which would exhibit enhanced and stable catalytic activity at low temperature in the presence of water and sulphur containing compounds are reported. Possible routes for preparing catalysts able to meet future regulations concerning methane emissions from lean-burn NGV vehicles are discussed.

Complete oxidation of methane at low temperature over noble metal based catalysts: a review

During the last decade a number of ceramic materials, mostly oxides have been suggested as new thermal barrier coating (TBC) materials. These new compositions have to compete with the state-of-the-art TBC material yttria stabilized zirconia (YSZ) which turns out to be difficult due to its unique properties. On the other hand YSZ has certain shortcomings especially its limited temperature capability above 1200 °C which necessitates its substitution in advanced gas turbines. In the paper an overview is tried on different new materials covering especially doped zirconia, pyrochlores, perovskites, and aluminates. Literature results and also results from our own investigations will be presented and compared to the requirements. Finally, the double-layer concept, a method to overcome the limited toughness of new TBC materials, will be discussed.

/pdf/overview-on-advanced-thermal-barrier-coatings-2buk8enwhe.pdf

Overview on advanced thermal barrier coatings

Low temperature oxidation of methane over Pd catalyst supported on metal oxides

Copper catalysts supported on alumina-based mixed oxides (Cu/Al2O3–MOx; M=Al, Ce, Co, Cr, Fe, Mg, Mn, Sn, Zn, and Zr) were investigated for CO removal in the methanol steam reformed gas. Cu/Al2O3–ZnO demonstrated excellent activity. The order of the activity for Cu/Al2O3–MOx with different M was Zn>Al>Cr>Mn>Mg. The highest catalytic activity is strongly related to the particle size of Cu. Spinel type Cu–Al–Zn oxides, formed after the preparation, gave rise to fine Cu particles which deposited on the support by reduction so that high catalytic activity is led by small Cu particles. Excess amount of Cu (>30 wt%) leads to low dispersion and causes formation of large particles and deterioration of catalytic activity. Although it is difficult to remove the trace CO in the reformed gas through water–gas-shift reaction, addition of O2 to the reformed gas is effective to enhance the CO removal through CO oxidation.

Selective removal of CO in methanol reformed gas over Cu-supported mixed metal oxides

Catalytic activities of supported Pd were investigated for low temperature oxidation of methane. Pd/SnO2 catalysts demonstrated excellent activity for methane oxidation in spite of their low surface area. The catalytic activity of Pd/SnO2 was strongly affected by the preparation procedure. Impregnation of Pd on SnO2 using aqueous solution of Pd(CH3COO)2 was most effective in enhancing the catalytic activity. The catalytic activity was also improved when well-crystallized SnO2 was employed as a support material. TEM observations revealed that catalytic activity is strongly influenced by the dispersion state of Pd. For the active catalysts, strong interaction between Pd and SnO2 support was observed in the adsorption of oxygen.

Low temperature oxidation of methane over Pd/SnO2 catalyst

Oxidation of methane over Pd/mixed oxides for catalytic combustion

Supported Cu catalysts were investigated for CO removal in a gas mixture after methanol steam reforming. Removal of CO in the post-reforming gas was effectively promoted by the addition of oxygen in the gas mixture. Not only water gas shift reaction (WGSR; CO + H 2 O → CO 2  + H 2 ) but also CO oxidation reaction (CO + 1/2O 2  → CO 2 ) was effective in reducing the CO concentration. Although, H 2 oxidation also proceeded by added oxygen, the concentration of CO significantly decreased without consuming a large amount of H 2 with an increase in oxygen concentration. The equilibrium concentration obtained from thermodynamic data indicates that the reaction is desirable at lower temperatures. Cu/Al 2 O 3 –ZnO demonstrated an excellent activity for catalytic removal of CO by oxygen-assisted WGSR. The activity was enhanced without increasing H 2 conversion by employing longer contact time. These results indicate that the design of an active shift/oxidation catalyst operative at 100–150°C is a possible method for removal of very small amounts of CO in the reformed fuel.

Koshi Sekizawa

Papers

Low temperature oxidation of methane over Pd catalyst supported on metal oxides

Selective removal of CO in methanol reformed gas over Cu-supported mixed metal oxides

Low temperature oxidation of methane over Pd/SnO2 catalyst

Oxidation of methane over Pd/mixed oxides for catalytic combustion

CO removal by oxygen-assisted water gas shift reaction over supported Cu catalysts