Environmental Engineering Reference
In-Depth Information
S H 2
S CO 2
S CH 4
S Coke
T (°C)
FIGURE 2.4 Selectivities of ethanol reforming as a function of temperature (H2O/EtOH  =  3.7).
Source : Reproduced with permission from Fierro et al. [9].
Ni/La 2 O 3 catalyst exhibits high activity and good long-term stability for
steam reforming of ethanol and is a good candidate for ethanol reforming
processors for fuel cell applications [8]. Another study has found that oxida-
tive reforming of biomass-derived ethanol can be carried out over an inex-
pensive Ni-Cu/SiO 2 catalyst with respect to solid polymer fuel cell (SPFC)
applications [9]. The reaction can be performed either under diluted condi-
tions (with helium as diluent) or under conditions corresponding to an
on-board reformer. Selectivity of ethanol reforming depends on a number of
operating parameters, including reaction temperature, H 2 O/EtOH molar
ratio, and O 2 /EtOH molar ratio of the feed to the reformer. Figure 2.4 shows
the effect of the reaction temperature on the selectivity of the reforming
reaction. The hydrogen content and the CO 2 /CO x molar ratio in the outlet
gases have been used as parameters to optimize the operating conditions in
the reforming reactor. The tests carried out at on-board reformer conditions
have shown that an H 2 O/EtOH molar ratio  =  1.6 and an O 2 /EtOH molar
ratio = 0.68 at 973 K allow a hydrogen-rich mixture (33%) considered of
high interest for SPFC. The use of oxygen decreases the production of
methane and coke that, in turn, increases the lifetime of the catalyst, which
has been demonstrated to exhibit good long-term stability.
In a recent study, dielectric barrier discharge (DBD), the electrical dis-
charge between two electrodes separated by an insulating dielectric barrier,
was used for the generation of hydrogen from ethanol reforming [10]. It was
found that the increase of ethanol flow rate decreased ethanol conversion
efficiency and hydrogen yield, and high water/ethanol ratio and addition of
oxygen were advantageous for hydrogen production. Figure 2.5 shows the
Search WWH ::

Custom Search