A series of manganese-cerium oxide catalysts were prepared by co-precipitation method and used for low temperature selective catalytic reduction (SCR) of NO x with ammonia in the presence of excess O 2 . These catalysts were characterized by X-ray diffraction (XRD), surface area measurement and FTIR. The experimental results showed that the best Mn-Ce mixed-oxide catalyst yielded 95% NO conversion at 150 °C at a space velocity of 42,000 h −1 . As the manganese content was increased from 0 to 40% (i.e. the molar ratio of Mn/(Mn+Ce)), NO conversion increased significantly, but decreased at higher manganese contents. The most active catalyst was obtained with a molar Mn/(Mn+Ce) ratio of 0.4. Only N 2 rather than N 2 O was found in the product when the temperature was below 150 °C. At higher temperatures, trace amounts of N 2 O were detected. A mechanistic pathway for this reaction was proposed based on earlier findings and FTIR results obtained in this work. The initial step was the adsorption of NH 3 on Lewis acid sites of catalyst, followed by reaction with nitrite species to produce N 2 and H 2 O. Possible intermediates are proposed and all the intermediates could transform into NH 2 NO, which could further react to produce N 2 and H 2 O.

MnOx-CeO2 mixed oxides prepared by co-precipitation for selective catalytic reduction of NO with NH3 at low temperatures

A review on surface modification of activated carbon for carbon dioxide adsorption

https://dspace.library.uu.nl/bitstream/handle/1874/26040/Catal.Today-Weckhuysen-2003.pdf?sequence=1

Chemistry, spectroscopy and the role of supported vanadium oxides in heterogeneous catalysis

Nanocrystals with advanced magnetic or optical properties have been actively pursued for potential biological applications, including integrated imaging, diagnosis and therapy. Among various magnetic nanocrystals, FeCo has superior magnetic properties, but it has yet to be explored owing to the problems of easy oxidation and potential toxicity. Previously, FeCo nanocrystals with multilayered graphitic carbon, pyrolytic carbon or inert metals have been obtained, but not in the single-shelled, discrete, chemically functionalized and water-soluble forms desired for biological applications. Here, we present a scalable chemical vapour deposition method to synthesize FeCo/single-graphitic-shell nanocrystals that are soluble and stable in water solutions. We explore the multiple functionalities of these core-shell materials by characterizing the magnetic properties of the FeCo core and near-infrared optical absorbance of the single-layered graphitic shell. The nanocrystals exhibit ultra-high saturation magnetization, r1 and r2 relaxivities and high optical absorbance in the near-infrared region. Mesenchymal stem cells are able to internalize these nanoparticles, showing high negative-contrast enhancement in magnetic-resonance imaging (MRI). Preliminary in vivo experiments achieve long-lasting positive-contrast enhancement for vascular MRI in rabbits. These results point to the potential of using these nanocrystals for integrated diagnosis and therapeutic (photothermal-ablation) applications.

FeCo/graphitic-shell nanocrystals as advanced magnetic-resonance-imaging and near-infrared agents

Low-temperature selective catalytic reduction of NOx with NH3 over metal oxide and zeolite catalysts—A review

Carbon-encapsulated Fe nanoparticles from detonation-induced pyrolysis of ferrocene

Formation and reaction of ammonium sulfate salts on V2O5/AC catalyst during selective catalytic reduction of nitric oxide by ammonia at low temperatures

Simultaneous removal of SO2 and NOx from flue gas using a CuO/Al2O3 catalyst sorbent: I. Deactivation of SCR activity by SO2 at low temperatures

Combined effect of H 2 O and SO 2 on V 2 O 5 /AC the activity of catalyst for selective catalytic reduction (SCR) of NO with NH 3 at lower temperatures was studied. In the absence of SO 2 , H 2 O inhibits the catalytic activity, which may be attributed to competitive adsorption of H 2 O and reactants (NO and/or NH 3 ). Although SO 2 promotes the SCR activity of the V 2 O 5 /AC catalyst in the absence of H 2 O, it speeds the deactivation of the catalyst in the presence of H 2 O. The dual effect of SO 2 is attributed to the SO 4 2− formed on the catalyst surface, which stays as ammonium-sulfate salts on the catalyst surface. In the absence of H 2 O, a small amount of ammonium-sulfate salts deposits on the surface of the catalyst, which promote the SCR activity; in the presence of H 2 O, however, the deposition rate of ammonium-sulfate salts is much greater, which results in blocking of the catalyst pores and deactivates the catalyst. Decreasing V 2 O 5 loading decreases the deactivation rate of the catalyst. The catalyst can be used stably at a space velocity of 9000 h −1 and temperature of 250 °C.

Combined Effect of H2O and SO2 on V2O5/AC Catalysts for NO Reduction with Ammonia at Lower Temperatures

NO reduction with NH3 over activated carbon-supported copper oxide (CuO/AC) catalyst was studied at low temperatures (30-250 degrees C). The attention was focused on the effects of preparation parameters, reaction temperature and SO2 on the structure and activity of the catalyst. The catalysts show high activities for NO reduction with NH3 in the presence of O-2 at temperatures above 180 degrees C and are gradually deactivated at temperatures below 180 degrees C. Cu2O exists in the catalyst and results in low initial activity but it is easily oxidized into active CuO by O-2 during the NO-NH3-O-2 reaction. Calcination temperature and Cu loading of the catalyst strongly influence the activity and structure of the catalyst. The catalyst with 5 wt% Cu loading and calcined at 250 degrees C shows the highest activity. The activities of the catalysts with higher Cu loadings and/or calcined at higher temperatures are relatively low, mainly derived from aggregation of copper species. The CuO/AC catalyst is greatly deactivated by SO2 due to the formation of CuSO4 which is inactive at low temperatures. (C) 2000 Elsevier Science B.V. All rights reserved.

Zhenyu Liu

Papers

Carbon-encapsulated Fe nanoparticles from detonation-induced pyrolysis of ferrocene

Formation and reaction of ammonium sulfate salts on V2O5/AC catalyst during selective catalytic reduction of nitric oxide by ammonia at low temperatures

Simultaneous removal of SO2 and NOx from flue gas using a CuO/Al2O3 catalyst sorbent: I. Deactivation of SCR activity by SO2 at low temperatures

Combined Effect of H2O and SO2 on V2O5/AC Catalysts for NO Reduction with Ammonia at Lower Temperatures

NO reduction with NH3 over an activated carbon-supported copper oxide catalysts at low temperatures