TY - JOUR
T1 - Oxidative dehydrogenation of iso-butane to iso-butene I. Metal phosphate catalysts
AU - Takita, Yusaku
AU - Sano, Ken Ichi
AU - Kurosaki, Kazuo
AU - Kawataa, Noboru
AU - Nishiguchi, Hiroyasu
AU - Ito, Masami
AU - Ishihara, Tatsumi
N1 - Funding Information:
Part of this work has been carried out as a research project of The Japan Petroleum Institute commis-sionedb y the PetroleumE nergyCenter with a subsidy from the Ministry of InternationaTl rade and Industry.
PY - 1998/2/5
Y1 - 1998/2/5
N2 - Metal pyrophosphates catalyse the oxidative dehydrogenation of iso-butane to iso-butene at 450-550°C using a feed gas of 75 mol% iso-butane and 5% O2. Ni2P2O7 is the most selective catalyst with the iso-butene selectivity reaching to a maximum value of 82.2% at 550°C. Ag4P2O7 and Zn2P2O7 are also effective, but the iso-butene selectivities were slightly lower than that of Ni2P2O7. Pyrophosphates of Mg, Cr, Co, Mn, and Sn catalyse the oxidative dehydrogenation, but the iso-butene selectivity was 43.8-65.7% at the temperature where the maximum iso-butene yield is observed. The optimum oxygen concentration for iso-butene formation was 5-15 mol%, but the increase in O2 concentration did not increase the iso-butene selectivity. No adsorbed oxygen species was found by means of TPD. The lattice oxygen of the pyrophosphates began to react with H2 at 200-400°C. Reactivity of the lattice oxygen of pyrophosphates can be estimated from the value of ΔH0f for the corresponding oxide. More than 2 desorption peaks were observed in the TPD spectra of NH3 adsorbed on the pyrophosphates, and a linear correlation was found between the concentration of acid amount of the catalysts and the specific rate of iso-butene formation. This strongly suggests that the acidic sites play a key role in the iso-butene formation.
AB - Metal pyrophosphates catalyse the oxidative dehydrogenation of iso-butane to iso-butene at 450-550°C using a feed gas of 75 mol% iso-butane and 5% O2. Ni2P2O7 is the most selective catalyst with the iso-butene selectivity reaching to a maximum value of 82.2% at 550°C. Ag4P2O7 and Zn2P2O7 are also effective, but the iso-butene selectivities were slightly lower than that of Ni2P2O7. Pyrophosphates of Mg, Cr, Co, Mn, and Sn catalyse the oxidative dehydrogenation, but the iso-butene selectivity was 43.8-65.7% at the temperature where the maximum iso-butene yield is observed. The optimum oxygen concentration for iso-butene formation was 5-15 mol%, but the increase in O2 concentration did not increase the iso-butene selectivity. No adsorbed oxygen species was found by means of TPD. The lattice oxygen of the pyrophosphates began to react with H2 at 200-400°C. Reactivity of the lattice oxygen of pyrophosphates can be estimated from the value of ΔH0f for the corresponding oxide. More than 2 desorption peaks were observed in the TPD spectra of NH3 adsorbed on the pyrophosphates, and a linear correlation was found between the concentration of acid amount of the catalysts and the specific rate of iso-butene formation. This strongly suggests that the acidic sites play a key role in the iso-butene formation.
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U2 - 10.1016/S0926-860X(97)00297-4
DO - 10.1016/S0926-860X(97)00297-4
M3 - Article
AN - SCOPUS:0013196612
SN - 0926-860X
VL - 167
SP - 49
EP - 56
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 1
ER -