An in situ combined temperature-programmed reduction-M�ssbauer spectroscopy of alumina-supported iron catalysts

摘要: Two 10% FeAl2O3 catalysts with supports of different surface areas were studied by means an in situ combined temperature-programmed reduction (TPR)-Mossbauer spectroscopy technique, which enabled a Mossbauer measurement to be obtained after any temperature. Various reactions occurring during the TPR process revealed. It was found that, although iron concentration high, considerably strong metal (oxide)-support interactions occurred catalyst higher area, and sample consisted three consecutive stages, namely, at around 460 °C, 790 above 850 °C. In first stage from 300 600 °C mainly Fe(III) Fe3O4 then Fe(II) aluminate took place. amazing find that over temperature range 470–600 converted into aluminates without consumption hydrogen, thereby increase amount observed when increasing 470 meantime, species remained unreduced also transformed these temperatures. second reduced, giving rise formation Fe(0). final stage, reduced accompanied migration ions octahedral sites less stable tetrahedral ones, thus facilitated reduction. Chemical control present 470–700 The lower area gave similar pattern reduction, but some varied features due extent metal-support interactions.