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Hydrogen production by methanol steam reforming: Catalytic performance of supported-Pd on zinc–cerium oxides’ nanocomposites

Paper ID Volume ID Publish Year Pages File Format Full-Text
45456 46412 2015 14 PDF Available
Title
Hydrogen production by methanol steam reforming: Catalytic performance of supported-Pd on zinc–cerium oxides’ nanocomposites
Abstract

•On the binary oxides SRM takes place; detrimental production of CO only occurs at high temperature.•The surface Pd–Zn alloy is a sine qua non condition to prevent the deleterious production of CO.•On ceria, Pd is only able to decompose methanol and to activate the RWGS reaction.•CO2 selectivity becomes better the higher the dispersion of ZnO is.•Higher ZnO dispersion on carbonate-derived supports causes better catalytic performance.

Two series of supported palladium catalysts (2 wt%) were prepared on ZnO–CeO2 nanocomposites (Zn-to-Ce atomic ratio between 0.5 and 2) obtained by oxalate or carbonate coprecipitation (OC and CC series, respectively). Methanol steam reforming (MSR) reaction was tested in a wide range of temperature (398–623 K) for CH3OH/H2O = 1/1 gas mixtures. Pd on pure CeO2 was only able to decompose methanol to CO, under 523 K, but the reverse water gas shift reaction took place at higher temperatures. The MSR reaction only occurred in the presence of zinc oxide and the selectivity to CO2 was higher for the CC series, due to the better dispersion of the ZnO phase over these carbonate-derived nanocomposites. Although the CO2 selectivity seems to be modulated by the reverse water gas shift reaction, the palladium supported on the mixed oxides was more stable than Pd/ZnO, which continuously deactivated. A detailed characterization by high resolution atomic microscopy, X-ray photoelectron spectroscopy and a novel carbon monoxide step chemisorption technique, proved the formation of bulk and surface PdZn alloying in the ternary catalyst, Pd supported on the nanosized ceria and zinc oxide supports. It is concluded that although a better catalytic stability was observed on the ZnO–CeO2 nanocomposites, the employment of temperatures higher than 450 K would impose an insurmountable limitation in terms of CO2 selectivity.

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Keywords
Fuel cells; Palladium dispersion; Palladium–zinc intermetallic; Clean energy
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Hydrogen production by methanol steam reforming: Catalytic performance of supported-Pd on zinc–cerium oxides’ nanocomposites
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 179, December 2015, Pages 262–275
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