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Alumina supported Co–K–Mo based mixed metal oxide type catalytic materials have been prepared by co-impregnation. These catalysts show excellent activity for carbon as well as diesel soot oxidation, which could be due to the redox properties of Mo and Co as well as to a synergistic effect of molybdenum, cobalt, and K contents. The catalyst containing 5 wt% molybdenum shows a lowering of carbon oxidation by about 190 °C under loose contact conditions as compared to the non-catalyzed reaction, as well as to bare alumina. Characterization studies suggest a composite nature of these materials, while thermal stability investigations confirm the stable nature. The selected catalyst has been studied by XPS, however, it is difficult to conclude which are the important factors contributing to the catalytic activity. It appears to be a synergistic effect of Co, K, and Mo components as these catalysts show much improved activity as compared to the individual components in supported and unsupported forms. [ABSTRACT FROM AUTHOR]

Ruthenium based catalysts show excellent catalytic activity for several oxidation reactions, however, their thermal stability has been a challenge. We have been successful in stabilizing ruthenium in perovskite structure, which results in a remarkable improvement in its thermal stability. La3.5Ru4.0O13 lanthanum ruthenate type perovskite was prepared by using various methods, including co-precipitation as well as a template method, which resulted in improved physical properties. This perovskite phase was found to be thermally very stable, possibly due to the 4+ oxidation state of ruthenium in a stable matrix. In this work, we have studied the catalytic properties of La3.5Ru4.0O13 phase for CO and hydrocarbon oxidation reactions. The lanthanum ruthenate shows active CO oxidation beyond about 150 and 170 °C for propene oxidation. The thermal and chemical stability of this material makes it suitable for various catalytic applications, while relatively insignificant poisoning by SO2 is an important observation to further explore. [ABSTRACT FROM AUTHOR]

Perovskite type catalysts with SrCoO3 and Sr0.8Ce0.2CoO3 compositions have been prepared by co-precipitation and other methods and, their catalytic activity towards diesel particulate matter (PM)/carbon oxidation has been evaluated under the loose contact condition. These catalysts show excellent catalytic activity for PM/carbon oxidation, despite their low surface area and under the loose contact condition. The synergistic effects of Ce incorporation in perovskite and presence of a small amount of potassium appears to be responsible for the high soot oxidation activity of these perovskite type materials. The Ce incorporation seems to be contributing by enhancing the redox property of the catalyst, while it appears unlikely that potassium is contributing by improving the catalyst–soot contact through its volatization. The catalysts show excellent thermal stability and stable activity under repeated cycles of use. [ABSTRACT FROM AUTHOR]

Lanthanum ruthenate materials with perovskite type structure can be easily synthesized with ruthenium in 4+ oxidation state. La3.5Ru4.0O13 type perovskite has been synthesized in unsupported and supported forms by using various methods. This perovskite type La3.5Ru4.0O13 phase shows high thermal stability and can therefore be used as a catalyst for high temperature applications, including those for auto-exhaust emission control. The material shows good catalytic activity for the carbon/soot oxidation in view of its possible application in diesel soot oxidation for regeneration of Diesel Particulate Filter. [ABSTRACT FROM AUTHOR]

Various amounts of ruthenia–cobaltate bimetallic catalyst supported on zirconia have been prepared by co-impregnation method and their catalytic activity towards soot/carbon oxidation has been evaluated using TG technique under the loose contact condition. These catalysts show good activity for carbon/soot oxidation, which is observed to be a factor of ruthenia content. The thermal stability experiments confirmed the stability of catalytic materials in air at least up to 900 °C. In this way, ruthenia can be easily dispersed on zirconia possibly through the solid solution formation, while its thermal stability can be significantly improved by introducing a transition metal namely cobalt. Formation of Ru–Co bimetallic clusters over zirconia is probably responsible for its thermal stability, while dissociative adsorption of oxygen on catalyst surface appears to be responsible for their catalytic activity. [ABSTRACT FROM AUTHOR]

Thermogravimetry (TG) and differential thermal analysis (DTA) were used to investigate the oxidation behavior of Ru/TiO2 and metallic Ru fine particles during heating in air in the range 20–1000 °C. Temperature ranges of the oxidation for two samples of Ru/TiO2 with the compositions (92 wt% Ru, 8 wt% TiO2) and (75 wt% Ru, 25 wt% TiO2) and for pure metallic Ru fine particle agglomerates were determined. It was assumed that after the partial oxidation of Ru in the sample containing 75 wt% Ru and 25 wt% TiO2 and in the pure metallic Ru a diffusion barrier was formed, preventing further oxidation of Ru in Ru/RuO2 and Ru/RuO2/TiO2 matrices. XRD and TEM were used for the sample characterization. [Copyright &y& Elsevier]