Conversion Of Nitrogen Monoxide Research Articles

Effects of SO2 on selective catalytic reduction of NO with NH3 over a TiO2 photocatalyst

The effect of SO2 gas was investigated on the activity of the photo-assisted selective catalytic reduction of nitrogen monoxide (NO) with ammonia (NH3) over a TiO2 photocatalyst in the presence of excess oxygen (photo-SCR). The introduction of SO2 (300 ppm) greatly decreased the activity of the photo-SCR at 373 K. The increment of the reaction temperature enhanced the resistance to SO2 gas, and at 553 K the conversion of NO was stable for at least 300 min of the reaction. X-ray diffraction, FTIR spectroscopy, thermogravimetry and differential thermal analysis, x-ray photoelectron spectroscopy (XPS), elemental analysis and N2 adsorption measurement revealed that the ammonium sulfate species were generated after the reaction. There was a strong negative correlation between the deposition amount of the ammonium sulfate species and the specific surface area. Based on the above relationship, we concluded that the deposition of the ammonium sulfate species decreased the specific surface area by plugging the pore structure of the catalyst, and the decrease of the specific surface area resulted in the deactivation of the catalyst.

Catalytic performance of Au/TS-1 in selective oxidation of nitrogen monoxide

In this article, supported Au/TS-1 catalysts were prepared and characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Their performance in the catalytic oxidation of nitrogen monoxide (NO) was evaluated, and the effect of reaction conditions on NO conversion was examined. The results indicated that the Au granules can be successfully loaded on the molecular sieve TS-1 and the catalysts Au/TS-1 obtained exhibited good crystallinity. The catalysts Au/TS-1 also exhibit excellent performance in the selective catalytic oxidation of NO at low temperature. Over the catalyst with an Au loading of 1.0%, with the molar fractions of NO and O2 in the feed being 1 × 10−3 and 0.1, respectively, and under a space velocity (GHSV) of 5000 h−1, the conversion of NO reaches 55% at 180°C and 78% at 260°C.

Catalytic reduction of nitrogen monoxide with propene over Nb/TiO2 mixed mechanically with Mn2O3

Selective catalytic reduction of nitrogen monoxide (NO) over a catalyst of mechanically mixed Nb/TiO2 and Mn2O3 (Mn2O3+Nb/TiO2) in an oxidizing atmosphere with propene (C3H6) was studied. The Mn2O3+Nb/TiO2 catalyst showed high activity for the reduction of NO to N2. The maximum conversion of NO to N2 was observed at 200∼300°C, with about 80% reduction of NO to N2. Mn2O3 enhanced the formation of NO2 from NO and the activation of propene to react with NO2 for reduction to N2.

Photocatalytic activity of dispersed TiO 2 particles deposited on glass fibers

Anatase TiO 2 particles were uniformly and dispersedly deposited on the surface of glass fibers by a liquid phase deposition (LPD) method from a TiF 4 aqueous solution upon addition of H 3BO 3 at 60 °C and then calcined at 60, 300 and 500 °C. The photocatalytic activity of the samples was evaluated by the photocatalytic oxidation of nitrogen monoxide (NO) in the gaseous phase. It was found that calcination temperatures obviously influenced the surface morphology and photocatalytic activity of the TiO 2 particles deposited on the glass fibers. At 300 °C, the TiO 2 samples exhibited the highest photocatalytic activity for the photocatalytic oxidation of NO and for the further conversion of NO 2 (from NO 2 to HNO 3) due to the enhancement of crystallization of anatase TiO 2 particles. At 500 °C, the photocatalytic activity of the sample decreased significantly due to the dropping of many TiO 2 particles from the glass fibers. Compared with the TiO 2 film photocatalyst, the TiO 2 particles deposited on the glass fibers exhibited a lower deactivation rate.

Selective decomposition of nitrogen monoxide to nitrogen in the presence of oxygen on RuO 2/Ag(cathode)/yttria-stabilized zirconia/Pd(anode)

Selective decomposition of nitrogen monoxide (NO) in the presence of oxygen was studied on electrochemical cells composed of yttria-stabilized zirconia (YSZ), electrodes, and surface oxide layers added. Decomposition activity was first measured on metal oxide/Pd(cathode)/YSZ/Pd(anode) at 773–973 K and 3.0 V of applied voltage in a flow of 50 ml/min containing 1000 ppm of NO and 6% of O 2 in helium. Coating of various metal oxides onto the cathode electrode greatly changed the decomposition activity; the order was RuO 2≫Pt>Rh 2O 3>Ni>none>Ag>WO 3. The activity of the system modified by RuO 2 has been investigated as a function of the kind of electrode, the applied voltage, and the reaction temperature. The cell of RuO 2/Ag(cathode)/YSZ/Pd(anode) was found to show the most excellent activity among the cells examined. The conversion of NO and the current efficiency for NO decomposition reached 31.8% and 11.8%, respectively, at 7 mA/cm 2 of current density induced by 2.2 V and 773 K, and the NO decomposition proceeded selectively about 13 times than the O 2 decomposition under the reaction condition.

木炭による一酸化窒素の還元

The reactivity of nitrogen monoxide (NO) with several kinds of commercial charcoals for the fuel use was examined at 300-500°C by using a pulse reaction technique (Table 1). Among the charcoals studied mitsumata (Edgeworthia) charcoal that contained the highest level of potassium exhibited the highest activity for reduction of NO into N2. The NO-C reaction was remarkably enhanced by Cu-Cr metal loaded on charcoals. Conversion of NO significantly increased in the presence of propene because, in addition to the NO-C reaction, the NO-propene reaction was promoted by potassium present in the charcoal (Table 2).