Page 223 - Advances in bioenergy (2016)

resulting in the production of CO-free hydrogen at temperatures as low as 350°C. The presence
of Pt has been found to promote the WGS reaction at low temperatures over alumina-supported
Ru–Pt catalysts. 33

In general, supported Pt catalysts seem to present higher activity and selectivity compared with
other metals for the LTSR of ethanol and are more widely studied. 30,34 Activity at 450°C was
34
found to vary in the order of Pt > Pd > Rh > Ru over CeO -supported catalysts. Similarly, it
2
has been found that the ranking of noble metal catalysts supported on Al O is the following:
2 3
24
1% Pd/Al O ≈ 0.5% Pt/Al O > 5% Ru/Al O > 2% Rh/Al O (Figure 9.2), with ethanol
2 3
2 3
2 3
2 3
conversion reaching 100% at 360°C over Pt and Pd catalysts. Product distribution showed that
over Pt, the main products are H , CH , CO, CO and, to a smaller extent, CH CHO. A
2
3
4
2
symmetric variation of CO and CO selectivities has been observed, implying production of
2
CO at the expense of CO, due to occurrence of the WGS reaction. Although Pd catalyst
2
exhibits comparable activity with Pt, it is characterized by low efficiency for the WGS
reaction. 24