A study of steam reforming of hydrocarbon fuels on Pd/ceria
Applied Catalysis A: General, 224 (1-2):
209-218 (January 2002)English.Abstract
Differential steam-reforming rates were measured for methane, ethane,
n-butane, n-hexane, 2,4-dimethylhexane, n-octane, cyclohexane, benzene,
and toluene over 1wt.% Pd/ceria between 620 and 770K and were compared
to rates observed on 1wt.% Pd/alumina and 1wt.% Pt/ceria. The H sub
2O:C ratios at which stable rates were observed on Pd/ceria depended
on the hydrocarbon, varying from less than 1:1 for methane to 3:1
for 2,4-dimethylhexane. In the series of alkanes from methane to
n-hexane, for a H sub 2O:C ratio of 2:1, the only products were CO,
CO sub 2, and H sub 2O and the rate of formation of CO sub 2 and
CO increased with carbon number. Benzene was also selectively converted
to CO sub x and H sub 2, but at lower rates than the alkanes with
the exception of methane. For 2,4-dimethylhexane and n-octane, a
significant amount of cyclohexane was observed in the initial products
and cyclohexane was selectively converted to benzene at low conversions.
Steam reforming of toluene also gave benzene as the initial product.
FTIR measurements of Pd/ceria under methane-steam-reforming conditions
indicate the formation of carbonates on the ceria. Pd/alumina showed
significantly lower rates than Pd/ceria and much lower CO sub 2:CO
ratios in the initial products, implying ceria plays an important
role in the reaction. Pt/ceria gave rates and selectivities that
were essentially identical to that of Pd/ceria. The implications
of these results for hydrocarbon fuel processing are discussed. copy
2002 Elsevier Science B.V. All rights reserved. 27 Refs.