화학공학소재연구정보센터
Catalysis Today, Vol.297, 104-112, 2017
Control of Hg-0 and NO from coal-combustion flue gases using MnOx-CeOx/mesoporous SiO2 from waste rice husk
MnOx- and MnOx-CeOx-impregnated SiO2 particles were developed from waste rice husk via a hydrothermal synthesis for removal of Hg-0 and NOx. MnOx of 5 or 20 wt% associated with 5 or 10 wt% CeOx was impregnated into resource-recovery mesoporous SiO2. The presence of MnOx and CeOx reduced the specific surface area (S-BET) and pore volume of the SiO2 particles. Nevertheless, MnOx(5%)-CeOx(5%)/SiO2 possessed the largest SBET (123 m(2) g(-1)) among the impregnated samples. Electron microscopy images show that the metal-oxideimpregnated SiO2 was plate-shaped with sizes of 3-10 mu m. Mn4+/Mn3+ and Ce4+/Ce3+ were the major valence states in the MnOx-CeOx/SiO2 samples; the ratio of Mn4+/Mn3+ increased as CeOx was present. The presence of both amorphous/highly dispersed and crystalline MnOx was confirmed by X-ray diffraction and Xray photoelectron spectroscopy. Removal of Hg-0 and NO was achieved by both MnOx/SiO2 and MnOx-CeOx/SiO2 at between 150 and 350 degrees C. MnOx-CeOx/SiO2 showed greater Hg and low-temperature NO removal potentials than MnOx/SiO2, with MnOx(20%)-CeOx(10%)/SiO2 having Hg-0 removal efficiency of 96% at 150 degrees C and nearly 100% reduction of NO under a broad operation window of 100-300 degrees C. These results indicate that resource recovery of waste rice husk for producing SiO2 adsorbent/catalyst for Hg-0 and NOx removal is successful.