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Selective hydrogenation of nitrate in water over Cu–Pd/mordenite

Paper ID Volume ID Publish Year Pages File Format Full-Text
49186 46564 2006 6 PDF Available
Title
Selective hydrogenation of nitrate in water over Cu–Pd/mordenite
Abstract

Hydrogenation of nitrate (NO3−) in water has been investigated by using Cu–Pd exchanged zeolites in a gas–liquid co-current flow system. Cu–Pd/mordenites prepared by ion-exchange at 383 K were highly selective for the hydrogenation of NO3− with H2 to N2 and N2O at 278–333 K. Among Cu–Pd/mordenites with various Cu/Pd ratios and loading amounts of metal, 1.2 wt.% Cu–0.5 wt.% Pd/mordenite (Cu/Pd = 4) were shown to display the highest selectivity for N2O (96%) at 278 K, with the generation of undesired by-product NH3 being suppressed. In addition, this catalyst was superior in the selectivity to other Cu–Pd/zeolites and Cu–Pd/γ-Al2O3. The concentrations of NH3 formed 1.2 wt.% Cu–0.5 wt.% Pd/mordenite at 278 K were only 1.4 and 2.0 ppm at near 100%-conversion for the initial concentrations of 100 and 200 ppm of NO3−, respectively. The product N2O being a greenhouse gas was hydrogenated entirely to N2 with 5 wt.% Pd/AC placed at the gas phase of outlet of reactor. Kinetic study has determined the activation energy to be 27 kJ mol−1 and the reaction order to be 0.5 with respect to the concentration of NO3−. Hydrogenation of nitrite (NO2−) also produced N2O selectively over 1.2 wt.% Cu–0.5 wt.% Pd/mordenite, supporting that the hydrogenation of NO3− proceeds through NO2− as an intermediate. It was confirmed that 1.2 wt.% Cu–0.5 wt.% Pd/mordenite exhibited a robust stability both in its activity and against the dissolution of metals during reaction at 278–333 K.

Keywords
Hydrogenation of nitrate; Cu–Pd catalyst; Zeolite; Groundwater
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Selective hydrogenation of nitrate in water over Cu–Pd/mordenite
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 65, Issues 1–2, 15 May 2006, Pages 31–36
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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