Catalytic activation of ceramic filter elements for combined particle separation, NOx removal and VOC total oxidation

The development of a catalytically active filter element for combined particle separation and NOx removal or VOC total oxidation, respectively, is presented. For NOx removal by selective catalytic reduction (SCR) a catalytic coating based on a TiO2–V2O5–WO3 catalyst system was developed on a ceramic filter element. Different TiO2 sols of tailor-made mean particle size between 40 and 190 nm were prepared by the sol–gel process and used for the impregnation of filter element cylinders by the incipient wetness technique. The obtained TiO2-impregnated sintered filter element cylinders exhibit BET surface areas in the range between 0.5 and 1.3 m2/g. Selected TiO2-impregnated filter element cylinders of high BET surface area were catalytically activated by impregnation with a V2O5 and WO3 precursor solution. The obtained catalytic filter element cylinders show high SCR activity leading to 96% NO conversion at 300 °C, a filtration velocity of 2 cm/s and an NO inlet concentration of 500 vol.-ppm. The corresponding differential pressures fulfill the requirements for typical hot gas filtration applications. For VOC total oxidation, a TiO2-impregnated filter element support was catalytically activated with a Pt/V2O5 system. Complete oxidation of propene with 100% selectivity to CO2 was achieved at 300 °C, a filtration velocity of 2 cm/s and a propene inlet concentration of 300 vol.-ppm.