Catalytic soot combustion of α-Fe/Ce-K-O nanocomposites via citrate-gel route

摘要

The binary phase, porous, nanocomposite xα-Fe/(1 - x)Ce_(0.9)-K_(0.1)-0 (x = 0.05-0.2) catalysts and the catalyst-coated honeycomb ceramic device have been prepared by the citrate-gel thermal decomposition-reduction process and the sol-gel assisted dip-coating method, respectively. The nanocomposite of fluorite-type structure CeO2 nanoparticles about 18-51 nm and α-Fe nanoparti-cles about 32 nm is obtained at 600 °C for 2 h in a deox-idization atmosphere and the a-Fe in nanocomposite has the suppression effect on grain growth of CeO2. With Fe content increasing from 0.05 to 0.1, the specific surface area for the nanocomposites increases dramatically from about 4.4 to 43.0 m~2/g, reaching a maximum value 57.7 m~2/g aXx = 0.15, and the pores vary from macropores to micro- or mesopores. Due to the presence of nano a-Fe, all the catalysts exhibit a very high soot catalytic activity, with the lowest T_(20) (255 °C) and T_(50) (291 °C) for the nanocomposite with x - 0.15, and it is confirmed by the bench test under practical diesel exhaust gases.