Microwave-assisted preparation of porous fibrous ceramic-based catalytic filter elements for the simultaneous removal of NOx and dust from high-temperature gases

Abstract Different drying conditions and three types of porous fibrous ceramics with different contents and dispersions of the silica-based binder were used to prepare catalytic filter elements (CFEs) for the simultaneous removal of NOx and dust, and their effects on the catalytic performances were also investigated. The results indicated that the content and dispersion of the silica-based binder had a significant effect on the catalytic activity of the CFE. The removal of useless binder in the pores and the inhibition of binder agglomeration could improve the NO conversion. Compared with traditional electric heating blast drying, microwave drying effectively inhibited the migration of titanium sol so that the catalyst in the prepared CFE had good uniformity and dispersion. Meanwhile, microwave drying changed the morphology, crystal grain, and pore structure of the catalyst support (TiO2), ultimately increasing the specific surface area. Furthermore, this study also determined that the optimal average output power for microwave drying was 385 W. With a filtration velocity of 1 m/min, NO and NH3 inlet concentrations of 600 ppm, and an O2 content of 5 vol%, the prepared CFE achieved more than 98% NO conversion in the temperature range of 250 to 350 °C, and its highest conversion of 100% was achieved at 275–325 °C.