Synergistic removal of nitrogen monoxide by non-thermal plasma and catalyst simultaneously

An experimental system of De-NO with plasma-catalyst（Cu zeolite） was established to investigate the differences between De- NO with plasma-catalyst and De-NO only with plasma, to provide the instruction for selecting appropriate catalyst and operating condition, The characteristics of De-NO with plasma and De-NO with plasma-catalyst were investigated comparatively by experiments. The experimental results show that De-NO with plasma-catalyst has high NO removal rate; Cu zeolite is an effective catalyst which can promote NO removal rate in plasma remarkably; De-NO with plasma-catalyst should be operated at low temperature and the temperature has opposite effects on the function of catalvst and plasma; water vapor and O2 can increase the NO removal rate.

Synergetic catalytic removal of chlorobenzene and NOχfrom waste incineration exhaust over MnNb0.4Ce0.2Oχcatalysts:Performance and mechanism study

Nb doped MnCe0.2Ox complex oxides catalysts prepared via a homogeneous precipitation method were investigated for synergistic catalytic removal of NOx and chlorobenzene(CB)at low temperatures.The MnNb0.4Ce0.2Ox catalyst with a molar ratio of Nb/Mn=0.4 exhibits excellent activity and the NOx and CB removal efficiency reaches 94.5%and 96%at 220℃,respectively.Furthermore,the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox still remains above 80%after injecting 300 ppm SO2 and 7 vol%H2 O for 36 h.In addition,the presence of CB and NOx+NH3 can improve the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox,respectively.The analysis results from N2-BET,Py-IR,H2-TPR and NH3-TPD reveal that the introduction of Nb increases the average pore size,pore volume and surface area,promoted the growth of Lewis acid amount obviously,and enhances redox ability of MnCe0.2Ox at 100-250℃.Moreover,the molecular migration process of NOx,NH3,CB and SO2 in NH3-SCR and CB oxidation reaction over MnNb0.4Ce0.2Ox catalysts were systematically studied.In situ DRIFTS,FT-IR and XPS also confirm that the adsorption of sulfate species and SO2 on the surface of MnNb0.4Ce0.2Ox is inhibited effectively by the introduction of Nb in the presence of SO2 and H2 O.Moreover,Nb additives also enhance the structural stability of MnNb0.4Ce0.2Ox,due to the interactions among Mn,Nb and Ce.The NH3-TPD,H2-TPR and in situ DRIFTS results also confirm that the MnNb0.4Ce0.2Ox still retains abundant acid sites and high redox ability in the presence of SO2 and H2O.In summary,MnNb0.4Ce0.2Ox catalysts represent a promising and effective candidate for controlling NOx and CB at low temperatures.

Synergistic catalytic removals of NO,CO and HC over CeO_2 modified Mn-Mo-W-O_x/TiO_2-SiO_2 catalyst

A series of Mn-Mo-W-O_x/TiO_2-SiO_2 catalysts was modified with CeO_2 using an extrusion molding method. The catalytic activities of the obtained catalysts were tested for the synergistic catalytic removals of CO, NO and C_3H_8. The ratio of catalyst composition on catalytic activities for NH_3-SCR was optimized, which reveals that the molar ratio of Ti/Si was 9：1 and the catalyst containing 1.5 wt% CeO_2 and 12 wt% Mn-Mo-W-O_x exhibits the best catalytic performances. These samples were characterized by XRD, N_2-BET, Py-IR, NH_3-TPD, SEM/element mapping, H_2-TPR and XPS, respectively. Results show that the optimal catalyst exhibits more than 99% NO conversion, 86% CO conversion and 100% C_3H_8 conversion under GHSV of 5000 h^（-1）. In addition, the GHSV has little influence on removal of NO when it is less than 15,000 h^（-1）. Furthermore, the addition of CeO_2 will enhance the surface acidity, increase Mn^（4＋）concentration and inhibit the grain growth, which are favorable for the excellent catalytic performance.Anyway,the 1.5 wt% CeO_2-12 wt% Mn-Mo-W-O_x/TiO_2-SiO_2 possesses outstanding redox properties,abundant acid sites and high Mn^（4＋） concentration, which provide a guarantee for synergistic catalytic removal of CO, NO and HC.

Comparative study of MCe_(0.75)Zr_(0.25)O_(y)(M=Cu,Mn,Fe)catalysts for selective reduction of NO by CO:Activity and reaction pathways

Basic oxygen furnace steelmaking leads to the production of CO-rich off-gas.When CO and NO are combined in off-gas,selective catalytic reduction by CO(CO-SCR)effectively achieves the synergistic removal of both pollutants.In this paper,CuCe_(0.75)Zr_(0.25)O_(y),MnCe_(0.75)Zr_(0.25)O_(y),and FeCe_(0.75)Zr_(0.25)O_(y) catalysts are prepared and evaluated for their CO-SCR activity,and the results show that the reaction system needs to be anaerobic;thus,the CO-SCR reaction can be dominant.The T_(90) values of CuCe_(0.75)Zr_(0.25)O_(y) and FeCe_(0.75)Zr_(0.25)O_(y) are 200℃ and 223℃,respectively.The activities of these two catalysts are higher than that of MnCe_(0.75)Zr_(0.25)O_(y)(T_(90)=375℃).Linear nitrate and bridged bidentate nitrate are the main intermediate species involved in NO conversion on the catalyst surface,and bidentate CO_(3)^(2-)􀀀coordination is the main intermediate species involved in CO conversion on the catalyst surface.CuCe_(0.75)Zr_(0.25)O_(y) has high lattice oxygen mobility and is more likely to react with NO and CO.In the presence of oxygen,most CO is oxidized by O_(2),which increases continuously to 100%,100%,and 98%for CuCe_(0.75)Zr_(0.25)O_(y),FeCe_(0.75)Zr_(0.25)O_(y),and MnCe_(0.75)Zr_(0.25)O_(y),respectively;additionally,CO is oxidized by O_(2),and the CO-SCR reaction cannot be carried out.