Premium
Bismuth‐Doped Ceria, Ce 0.90 Bi 0.10 O 2 : A Selective and Stable Catalyst for Clean Hydrogen Combustion
Author(s) -
Beckers Jurriaan,
Lee Adam F.,
Rothenberg Gadi
Publication year - 2009
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200900089
Subject(s) - dehydrogenation , chemistry , hydrogen , inorganic chemistry , catalysis , propene , bismuth , propane , combustion , hydrocarbon , selectivity , organic chemistry
Bismuth‐doped cerias are successfully applied as solid “oxygen reservoirs” in the oxidative dehydrogenation of propane. The lattice oxygen of the ceria is used to selectively combust hydrogen from the dehydrogenation mixture at 550 °C. This process has three key advantages: it shifts the dehydrogenation equilibrium to the desired products side, generates heat, aiding the endothermic dehydrogenation, and simplifies product separation (water vs. hydrogen). Furthermore, the process is safer, since it uses the catalyst’s lattice oxygen instead of gaseous oxygen. We show here that bismuth‐doped cerias are highly active and stable towards hydrogen combustion, and explore four different approaches for optimising their application in the oxidative dehydrogenation of propane: first, the addition of extra hydrogen which lowers hydrocarbon conversion by suppressing both combustion and coking; second, the addition of tin which completely inhibits coking; third, the addition of platinum which increases selectivity, but at the expense of lower activity. The best results are obtained through tuning the reaction temperature. At 400 °C, high activity and selectivity were obtained for the bismuth‐doped ceria Ce 0.90 Bi 0.10 O 2 . Here, 90% of the hydrogen feed is converted at 98% selectivity. This optimal reaction temperature can be rationalised from the hydrogen and propene temperature‐programmed reduction (TPR) profiles: 400 °C lies above the reduction maximum of hydrogen, yet below that of propene. That is, this temperature is sufficiently high to facilitate rapid hydrogen combustion, but low enough to prevent hydrocarbon conversion.