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Selective Hydrogen Oxidation in the Presence of C 3 Hydrocarbons Using Perovskite Oxygen Reservoirs
Author(s) -
Beckers Jurriaan,
Drost Ruben,
van Zandvoort Ilona,
Collig Paul F.,
Rothenberg Gadi
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800039
Subject(s) - dehydrogenation , catalysis , selectivity , chemistry , hydrogen , inorganic chemistry , redox , oxygen , perovskite (structure) , endothermic process , chemical looping combustion , propane , organic chemistry , adsorption
Perovskite‐type oxides, ABO 3 , can be successfully applied as solid “oxygen reservoirs” in redox reactions such as selective hydrogen combustion. This reaction is part of a novel process for propane oxidative dehydrogenation, wherein the lattice oxygen of the perovskite is used to combust hydrogen selectively from the dehydrogenation mixture at 550 °C. This gives three key advantages: it shifts the dehydrogenation equilibrium to the side of the desired products, heat is generated, thus aiding the endothermic dehydrogenation, and it simplifies product separation (H 2 O vs H 2 ). Furthermore, the process is safer since it uses the catalysts’ lattice oxygen instead of gaseous O 2 . We screened fourteen perovskites for activity, selectivity and stability in selective hydrogen combustion. The catalytic properties depend strongly on the composition. Changing the B atom in a series of LaBO 3 perovskites shows that Mn and Co give a higher selectivity than Fe and Cr. Replacing some of the La atoms with Sr or Ca also affects the catalytic properties. Doping with Sr increases the selectivity of the LaFeO 3 perovskite, but yields a catalyst with low selectivity in the case of LaCrO 3 . Conversely, doping LaCrO 3 with Ca increases the selectivity. The best results are achieved with Sr‐doped LaMnO 3 , with selectivities of up to 93 % and activities of around 150 μmol O m −2 . This catalyst, La 0.9 Sr 0.1 MnO 3 , shows excellent stability, even after 125 redox cycles at 550 °C (70 h on stream). Notably, the activity per unit surface area of the perovskite catalysts is higher than that of doped cerias, the current benchmark of solid oxygen reservoirs.