,
Selective production of hydrogen for fuel cells via oxidative steam reforming of methanol over CuZnAl(Zr)-oxide catalysts
Applied Catalysis A: General, 213 (1): 47-63 (мая 2001)English.
Аннотация
Fuel cell powered vehicles using hydrogen (H sub 2) as a fuel are
currently being developed in an effort to mitigate the emissions
of green house gases such as CO sub 2, NO sub x, and hydrocarbons.
The H sub 2 fuel is extracted from methanol onboard a vehicle by
steam reforming of methanol (SRM) reaction. A considerable amount
of CO is produced as a by-product, which is a poison to the Pt anode
of the fuel cell. Very recently, we have demonstrated that a combined
SRM and partial oxidation of methanol (POM), which we labeled as
öxidative steam reforming of methanol (OSRM)" reaction is more efficient
for the selective production of H sub 2 relatively at a lower temperature
of around 230 degree C over CuZnAl(Zr)-oxide catalysts derived from
hydroxycarbonate precursors containing hydrotalcite (HT)-like layered
double hydroxides (LDHs)/aurichalcite phases. There are several operating
parameters such as catalyst composition, reaction temperature, O
sub 2/CH sub 3OH and H sub 2O/CH sub 3OH molar ratios and methanol
injection rate that are need to be optimized in order to produce
H sub 2 suitable for fuelling a fuel cell. In the present study,
we have investigated the effect of these variable parameters on the
catalytic performance over a series of CuZnAl- and CuZnAlZr-oxide
catalysts. Our study indicated that among the CuZn-based catalysts,
those containing Zr were the most active. The optimum O sub 2/CH
sub 3OH and H sub 2O/CH sub 3OH molar ratios should be in the ranges
0.20-0.30 and 1.3-1.6, respectively, in order to achieve a better
catalytic performance. Studies of the effect of methanol contact
time on the catalytic performance over a Zr-containing catalyst revealed
that the OSRM reaction proceeds through the formation of formaldehyde
intermediate. CO was produced as a secondary product by the decomposition
of formaldehyde and it is subsequently transformed into CO sub 2
and H sub 2 by the water-gas shift (WGS) reaction. copy 2001 Elsevier
Science B.V. 40 Refs.
