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Production of hydro...
Production of hydrogen from methanol over binary Cu/ZnO catalysts - Part I. Catalyst preparation and characterisation
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Agrell, J. (författare)
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- Boutonnet, Magali (författare)
- KTH,Kemiteknik
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Melian-Cabrera, I. (författare)
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Fierro, J. L. G. (författare)
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(creator_code:org_t)
- Elsevier BV, 2003
- 2003
- Engelska.
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 253:1, s. 201-211
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Mixed copper-zinc oxide catalysts (Cu/ZnO) were prepared by two different techniques, i.e. from hydroxycarbonate precursors formed in aqueous solution and from oxalate precursors formed in water-in-oil microemulsion. Their physicochemical properties were characterised by nitrogen adsorption-desorption, N2O chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and oxidation (TPO). The BET surface areas ranged from 34 to 87 m(2)/g, depending on the method of preparation. Cu surface areas between 6.6 and 22 m(2)/g were measured. It was a general observation that catalysts prepared by microemulsion technique had lower Cu dispersions than expected (3.4-5.7%), due to a proposed partial embedding of Cu in ZnO. The catalyst prepared by carbonate co-precipitation exhibited a significantly higher Cu dispersion (10.3%). In addition, this catalyst displayed better resistance to successive TPR/TPO than the microemulsion catalysts, which exhibited significant Cu crystallite growth. However, the microemulsion route provided well-mixed materials with a narrow particle size distribution and the possibility to obtain high BET surface areas (up to 87 m(2)/g) by controlling the water/surfactant ratio in the microemulsion. XPS measurements revealed the existence of Cu+ species on the surface of both types of catalysts after exposure to a O-2/CH3OH mixture. The surface composition of the hydroxycarbonate-derived sample was unaffected by reduction in hydrogen and exposure to O-2/CH3OH, while Zn-enrichment on the surface was observed in the microemulsion catalysts after reduction, indicating sintering of the Cu particles. These observations were consistent with the TPR/TPO measurements.
Nyckelord
- Cu/ZnO catalyst
- hydroxycarbonate precursor
- oxalate precursor
- microemulsion
- characterisation
- N2O chemisorption
- XPS
- TPR/TPO
- ray photoelectron-spectroscopy
- gel-oxalate coprecipitation
- gas shift
- reaction
- partial oxidation
- surface characterization
- structural-changes
- oxide catalysts
- chemical-state
- copper surface
- zinc-oxide
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- art (ämneskategori)
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