Catalytic treating of gas pollutants over cobalt catalyst supported on porous carbons derived from rice husk and carbon nanotube

Porous carbons were prepared from rice husks, commercial coconut-shell-derived carbon, and carbon nanotube (CNT) by activation with CO2, KOH, and ZnCl2. Cobalt catalysts were supported on the six different porous carbons by excess-solution impregnation, and were used to carry out reactions with different constituents such as NO + CO, toluene, NO + toluene, and NO + CO + toluene in the presence of 6% O2 at 250 °C to evaluate the activity of porous catalysts. The properties of the catalysts were analyzed by X-ray powder diffractometer (XRD), a field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and an X-ray energy dispersive spectrometer (EDS). The cobalt catalysts supported on rice-husk-based carbon activated by CO2 and those on commercial-activated-carbon re-treated by KOH showed 100% conversion on toluene oxidation. CNT-cobalt catalyst showed 63% NO conversion with CO and 46% with toluene at 250 °C. Among the six porous supported catalysts, the cobalt catalysts prepared with CNT and rice-husk-derived carbon by using CO2 showed the best catalytic activity and thermal stability when compared to the others.