TY - JOUR
T1 - SrO·Al2O3 mixed oxides
T2 - A promising class of catalysts for oxidative coupling of methane
AU - Baidya, Tinku
AU - Van Vegten, Niels
AU - Verel, René
AU - Jiang, Yijiao
AU - Yulikov, Maxim
AU - Kohn, Thomas
AU - Jeschke, Gunnar
AU - Baiker, Alfons
PY - 2011/7/25
Y1 - 2011/7/25
N2 - Varying the composition of Sr-Al oxides, mixed as well as single phase compounds were prepared and characterized extensively by XRD, NMR, TEM, EPR, XPS, and TPD. Depending on synthesis method and precursors, Sr/Al-based materials with different crystalline phases (e.g., Sr3Al 4O9·2H2O, double perovskite, SrAl 4O7, SrAl2O4, and SrCO3) were obtained. Apart from these crystalline phases, several other species were present, as identified by solid state NMR and TG-MS. The ratio of tetrahedrally to octahedrally coordinated Al (AlIV/AlVI) in the Sr/Al mixed oxides increased from 0.5 (pure alumina) to 5.2 in Sr/Al = 1.25, as determined by solid state NMR. The performance of these catalysts in the oxidative coupling of methane depended on the AlIV/AlVI ratio, both activity as well as C2+ selectivity increased with increasing Sr-content. The catalyst with a Sr/Al ratio of 1.25 showed a performance comparable to the well-known catalyst 1.9%Mn-4%Na2WO 4/SiO2 under the conditions used (810 °C, CH 4:O2 = 108:22, GHSV ∼ 26,000 L/kgcat h).
AB - Varying the composition of Sr-Al oxides, mixed as well as single phase compounds were prepared and characterized extensively by XRD, NMR, TEM, EPR, XPS, and TPD. Depending on synthesis method and precursors, Sr/Al-based materials with different crystalline phases (e.g., Sr3Al 4O9·2H2O, double perovskite, SrAl 4O7, SrAl2O4, and SrCO3) were obtained. Apart from these crystalline phases, several other species were present, as identified by solid state NMR and TG-MS. The ratio of tetrahedrally to octahedrally coordinated Al (AlIV/AlVI) in the Sr/Al mixed oxides increased from 0.5 (pure alumina) to 5.2 in Sr/Al = 1.25, as determined by solid state NMR. The performance of these catalysts in the oxidative coupling of methane depended on the AlIV/AlVI ratio, both activity as well as C2+ selectivity increased with increasing Sr-content. The catalyst with a Sr/Al ratio of 1.25 showed a performance comparable to the well-known catalyst 1.9%Mn-4%Na2WO 4/SiO2 under the conditions used (810 °C, CH 4:O2 = 108:22, GHSV ∼ 26,000 L/kgcat h).
KW - Al MAS NMR
KW - EPR
KW - Oxidative coupling of methane
KW - Oxygen ion radicals
KW - Strontium-aluminum oxides
UR - http://www.scopus.com/inward/record.url?scp=79960217357&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2011.05.005
DO - 10.1016/j.jcat.2011.05.005
M3 - Article
AN - SCOPUS:79960217357
SN - 0021-9517
VL - 281
SP - 241
EP - 253
JO - Journal of Catalysis
JF - Journal of Catalysis
IS - 2
ER -