TY - JOUR
T1 - Oxidative dehydrogenation of iso-butane to iso-butene II. Rare earth phosphate catalysts
AU - Takita, Yusaku
AU - Sano, Ken Ichi
AU - Muraya, Toshio
AU - Nishiguchi, Hiroyasu
AU - Kawata, Noboru
AU - Ito, Masami
AU - Akbay, Taner
AU - Ishihara, Tatsumi
N1 - Funding Information:
This work has been carried out as a research project of The Japan Petroleum Institute, commissioned by the Petroleum Energy Center with the support of the Ministry of International Trade and Industry.
PY - 1998/5/25
Y1 - 1998/5/25
N2 - Among various rare earth phosphates, CePO4 and LaPO4 were found to catalyze the oxidative dehydrogenation of isobutane to iso-butene at 450-550°C using a feed gas of 75 mol% iso-butane and 5 mol% O2. As for the phosphates of Y, Pr, Nd, Gd, Er, and Yb, iso-butene was formed with a limited selectivity of 20-40% selectivity, and C3H6 formation and deep oxidation into CO and CO2 were promoted over the same temperature range. Temperature-programmed-desorption spectra of NH3 for CePO4 and LaPO4 consisted of two large desorption peaks with maxima at 100°C and 270°C suggesting that these phosphates have strong acid sites. But the rest of the phosphates have only weak acid sites. Rare earth phosphates have no adsorbed oxygen which can be desorbed up to 550°C. The lattice oxygen of CePO4 and PrPO4 can be reduced at 200°C and that of the rest of the phosphates at about 400°C. The amount of oxygen removed up to 550°C in TPR was smaller than the amount corresponding to a monolayer for all phosphates. Oxygen isotope equilibration experiments over CePO4 and LaPO4 revealed that only surface lattice oxygen can participate in the equilibration at 500°C and 550°C. It can be concluded that acidic character is a key factor in the selective oxidative dehydrogenation of iso-butane over the rare earth phosphate catalysts.
AB - Among various rare earth phosphates, CePO4 and LaPO4 were found to catalyze the oxidative dehydrogenation of isobutane to iso-butene at 450-550°C using a feed gas of 75 mol% iso-butane and 5 mol% O2. As for the phosphates of Y, Pr, Nd, Gd, Er, and Yb, iso-butene was formed with a limited selectivity of 20-40% selectivity, and C3H6 formation and deep oxidation into CO and CO2 were promoted over the same temperature range. Temperature-programmed-desorption spectra of NH3 for CePO4 and LaPO4 consisted of two large desorption peaks with maxima at 100°C and 270°C suggesting that these phosphates have strong acid sites. But the rest of the phosphates have only weak acid sites. Rare earth phosphates have no adsorbed oxygen which can be desorbed up to 550°C. The lattice oxygen of CePO4 and PrPO4 can be reduced at 200°C and that of the rest of the phosphates at about 400°C. The amount of oxygen removed up to 550°C in TPR was smaller than the amount corresponding to a monolayer for all phosphates. Oxygen isotope equilibration experiments over CePO4 and LaPO4 revealed that only surface lattice oxygen can participate in the equilibration at 500°C and 550°C. It can be concluded that acidic character is a key factor in the selective oxidative dehydrogenation of iso-butane over the rare earth phosphate catalysts.
UR - http://www.scopus.com/inward/record.url?scp=0013195334&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0013195334&partnerID=8YFLogxK
U2 - 10.1016/S0926-860X(98)00043-X
DO - 10.1016/S0926-860X(98)00043-X
M3 - Article
AN - SCOPUS:0013195334
SN - 0926-860X
VL - 170
SP - 23
EP - 31
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 1
ER -