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Highly reactive and selective Sn-Pd bimetallic catalyst supported by nanocrystalline ZSM-5 for aqueous nitrate reduction

Paper ID Volume ID Publish Year Pages File Format Full-Text
45084 46396 2016 10 PDF Available
Title
Highly reactive and selective Sn-Pd bimetallic catalyst supported by nanocrystalline ZSM-5 for aqueous nitrate reduction
Abstract

•Nanocrystalline ZSM-5 supported bimetallic catalyst was developed to reduce NO3−.•Sn-Pd-NZSM-5 showed complete NO3− removal and high N2 selectivity in 1 h.•Fast reduction kinetics was due to subsequent electron transfer from Sn0 and Sn2+.•Complete NO3− removal and high N2 selectivity continued over five cycles.

A new bimetallic catalyst supported by environmentally benign nanocrystalline ZSM-5 (NZSM-5), was developed to reduce nitrate completely and selectively to nitrogen gas without producing nitrite. The catalyst was optimized by use under a variety of conditions (i.e., promoter metal type (Sn, Cu, Ag, Ni)), noble metal type (Pd, Pt, Au), promoter metal concentration (0–3.4 wt%), noble metal concentration (0–2.8 wt%), catalyst calcination temperature (0–550 °C), H2 flow rate (0–60 mL/min), and CO2 flow rate (0–60 mL/min). Complete nitrate removal with the highest nitrogen selectivity (91%) was achieved using 1%Sn-1.6%Pd-NZSM-5 catalyst under optimized conditions that included: initial nitrate concentration: 30 mg/L NO3-N; calcination temperature: 350 °C; H2 flow rate: 30 mL/min; and CO2 flow rate: 60 mL/min for 60 min. The estimated kinetic rate constant of the catalyst is 16.40 × 10−2 min−1, the catalyst-loading normalized rate constant is 65.60 × 10−2 min−1 gcat−1, while Pd-loading normalized rate constant is 410 × 10−2 L/min gPd−1. The catalyst showed remarkable nitrate removal (100%) and nitrogen selectivity (>88%) for up to five successive reactions with consistent kinetics. A 100% nitrate removal and >81% nitrogen selectivity was also achieved by the catalyst for five repeated cycles. However, the kinetics gradually slowed down to 4.36 × 10−2 min−1 over five repeated cycles, (still superior to fresh catalysts already reported in the literature). Characterization tests confirmed that the used catalyst was chemically stable, and that the decrease in its reactivity was due mainly to the sintering of metallic nano particles during the regeneration process.

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Keywords
Sn-Pd bimetallic catalyst; Nanocrystalline ZSM-5 support; Catalytic nitrate reduction
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Highly reactive and selective Sn-Pd bimetallic catalyst supported by nanocrystalline ZSM-5 for aqueous nitrate reduction
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 187, 15 June 2016, Pages 37–46
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
Online Support
Any Questions? feel free to contact us