Search

In this contribution we present the results of a parallel high-throughput screening (HTS), which was carried out to identify new catalysts for the total oxidation of methane, a chemical compound that shows a significantly higher global warming potential compared to carbon dioxide. An interesting application for these materials is the abatement of unburned methane in exhaust gases from biogas fueled lean burn engines. After the synthesis of a high variety of different materials by a sol-gel procedure and their evaluation by infrared thermography under simplified reaction conditions, the activity of the most promising candidates was validated under a complex exhaust gas composition in a conventional plug flow reactor. The aging behavior of the best catalysts from the HTS was studied in a tenfold parallel reactor setup. Only a small number of the studied materials exhibited an interesting long term stability during the aging procedure. With this approach a high number of potential materials can be rapidly reduced to only a few catalysts which are promising for a possible industrial application. [ABSTRACT FROM AUTHOR]

Five spinel-type catalysts AB2O4 (Co0.8Cr2O4, CoCr2O4, MnCr2O4, MgFe2O4 and CoFe2O4) were prepared and characterized by XRD, BET and FESEM techniques. The activity of these catalysts towards the combustion of methane was evaluated in a Temperature Programmed Combustion (TPC) apparatus. The half conversion temperature of methane over the Co0.8Cr2O4 catalyst was 369 °C with a W/F = 0.12 g s/cm3. On the basis of Temperature Programmed Desorption (TPD) of oxygen as well as of catalytic combustion runs, the prevalent activity of the Co0.8Cr2O4 catalyst could be explained by its higher capability to deliver suprafacial chemisorbed oxygen species. This catalyst, promoted by the presence of 1 wt% of Pd, deposited by wet impregnation, was lined on cordierite monoliths and then tested in a lab-scale test rig. The combination of Pd and Co0.8Cr2O4 catalysts enables half methane conversion at 340 °C (GHSV = 10,000 h?1), a performance similar to that of conventional 4 wt% Pd-? Al2O3 catalysts but guaranteed with just a four-fold lower amount of noble metal. Both the catalysts in powder and the monolith hosting the Co0.8Cr2O4 + 1 wt% Pd catalyst, submitted to a thermal ageing treatment in air at 700 °C for 12 h, displayed a negligible deactivation. [ABSTRACT FROM AUTHOR]