Oxidative dehydrogenation of ethane over Cr/ZSM-5 catalysts using CO2 as an oxidant.
Highly active catalysts for oxidative dehydrogenation of ethane with CO2 were characterized by temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), Fourier transform infrared (FTIR) spectroscopy, and X-ray absorption fine-structure (XAFS) analysis. In the active catalysts, Cr/H-ZSM-5 (SiO2/Al2O3 > 190), Cr6+ = O, or possibly Cr5+ = O was the catalytic species on the zeolite support. In contrast, little Cr6+ (or Cr5+) was detected in the less-active catalysts. The Cr6+ (or Cr5+) species was reduced to an octahedral Cr3+ species by treatment with ethane at 773 K, and the reduced Cr species was reoxidized to the Cr6+ (or Cr5+) species by treatment with CO2 at 673-773 K. The Cr redox cycle played an important role in the catalyst's high activity.
Mimura
Naoki
N
Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan. n.mimura@aist.go.jp
Okamoto
Masaki
M
Yamashita
Hiromi
H
Oyama
S Ted
ST
Murata
Kazuhisa
K