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Quantitative room-temperature mineralization of airborne formaldehyde using manganese oxide catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
46719 46446 2011 8 PDF Available
Title
Quantitative room-temperature mineralization of airborne formaldehyde using manganese oxide catalysts
Abstract

Manganese oxide-based catalysts have been synthesized and tested for the abatement of formaldehyde, an ubiquitous indoor pollutant which is not effectively eliminated by most air cleaning technologies. Catalysts were prepared by co-precipitation of MnSO4 and NaMnO4 followed by curing at 100, 200 and 400 °C. Characterization was performed using X-ray diffractometry (XRD), porosimetry, scanning electron microscopy (SEM), and inductively coupled plasma-mass spectrometry (ICP-MS). Diffractograms of samples treated at 100 and 200 °C matched those of nsutite and cryptomelane/manjiroite structures, with high BET surface area (up to 149 m2 g−1) and small particle size (<50 nm), while curing at 400 °C yielded pyrolusite with lower effective surface area. Room temperature catalytic oxidation of airborne formaldehyde was studied by supporting the catalyst on a particulate filter media placed in a flow system, under stable upstream formaldehyde concentrations between 30 and 200 ppb. Two different face velocities (v = 0.2 and 50 cm s−1) were studied to evaluate the oxidation efficiency under different flow regimes using formaldehyde-enriched laboratory air at 25–30% relative humidity. Results showed consistent single-pass formaldehyde oxidation efficiency greater than 80% for the synthesized catalysts, which remained active over at least 35 days of continuous operation at v = 0.2 cm s−1 and were able to process up to 400 m3 of air at v = 50 cm s−1 without appreciable deactivation. Operation under high relative humidity (>90% RH) produced only a small reversible reduction in formaldehyde removal. Most significantly, 100% mineralization yields were verified by quantifying CO2 formation downstream of the catalyst for upstream formaldehyde concentrations as high as 6 ppm and a face velocity of v = 13 cm s−1. In contrast, a filter loaded with commercially available MnO2 did not remove appreciable amounts of formaldehyde at v = 50 cm s−1, and yielded <20% initial removal when operated at a very low face velocity (v = 0.03 cm s−1). Due to the relatively low costs of synthesis and deployment of these catalysts, this technology is promising for maintaining low indoor formaldehyde levels, enabling energy-saving reductions of building ventilation rates.

Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights• Synthesis of manganese oxide-based catalysts (nsutite and cryptomelane/manjiroite). • High surface area and porosity, and small crystal size. • Efficient removal of indoor formaldehyde. • Complete mineralization of formaldehyde. • High activity maintained after processing up to 400 m3 of formaldehyde-laden air.

Keywords
Manganese oxide catalysts; Room-temperature oxidation; Mineralization; Indoor air; Formaldehyde
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Quantitative room-temperature mineralization of airborne formaldehyde using manganese oxide catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 107, Issues 1–2, 31 August 2011, Pages 34–41
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