IRON TELLURIUM SELENIUM MIXED-OXIDE CATALYSTS FOR THE SELECTIVE OXIDATION OF PROPYLENE TO ACROLEIN

Iron-tellurium-selenium mixed oxide catalysts prepared by coprecipitation from aqueous solution have been investigated for the propylene to acrolein reaction in the temperature range 543-773 K. Infrared spectroscopy, electron dispersive X-ray analysis, X-ray diffraction, and isotopic tracer techniques have also been employed to characterize this catalytic system. Properties of the Fe-Te-Se mixed oxide catalysts have been compared with Fe-Te mixed oxides in an effort to deduce the functionality of Se. The selenium in the Fe-Te-Se-O catalyst has been found to be the hydrocarbon activating site. The activation energies for the acrolein and carbon dioxide formation are 71 and 54 kJ/mol, respectively. Reactions carried out with 18O2have shown lattice oxygen to be primarily responsible for the formation of both acrolein and carbon dioxide. The initial and rate-determining step for acrolein formation is hydrogen abstraction as determined by an isotope effect associated with the C3D6reaction. No isotope effect is observed for carbon dioxide formation from C3D6, suggesting that CO2is formed by parallel, not consecutive, oxidation of propylene. © 1990, American Chemical Society. All rights reserved.