Activity and characterization of Cu/Zn, Cu/Cr and Cu/Zr on gamma-alumina for methanol reforming for fuel cell vehicles

• The influence of catalyst properties on the activity and selectivity of hydrogen generation by methanol reforming over copper-based catalysts impregnated on gamma-alumina pellets has been investigated. In the experiments, three sets of copper-based catalysts with various compositions were tested: Cu/Zn/Al2O3, Cu/Cr/Al2O3 and Cu/Zr/Al2O3. The catalysts were characterized using temperature programmed reduction (TPR), temperature programmed oxidation (TPO), SEM-EDS, Brunauer-Emmett-Teller (BET) surface area measurement and X-ray diffraction (XRD). The copper surface area was determined by pulse chemisorption using N2O. We found a correlation between the copper surface area and catalytic activity. The activity tests were performed in a fixed bed reactor with 15 g of spherical catalyst pellets using a gas hourly space velocity (GHSV) of 25,000. The results of the activity tests indicate that the choice of promoter and the catalyst composition greatly influence the activity as well as the selectivity for CO2 formation. The highest conversions were achieved for the zinc-containing catalysts (Cu/Zn/Al2O3) for both steam reforming and the combined reforming process. Complete conversion of methanol was only obtained for the zinc-containing catalysts when running the steam reforming process. The combined reforming process generally yielded A product stream containing lower carbon monoxide concentrations compared to steam reforming at the equivalent reactor temperature for all of the catalysts tested.

Nyckelord

methanol reforming

catalyst characterization

TPR/TPO

pulse chemisorption

SEM-EDS

XRD

hydrogen generation

copper-based catalysts

partial oxidation

selective production

hydrogen-production

surface-area

co tolerance

catalysts

mechanism

alloys

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