The catalytic behaviour of alfa-Fe2O3- based catalysts in the toluene ammoxidation reaction was investigated in a continuous fixed-bed microreactor at 673 K, under atmospheric pressure. Catalysts were prepared and characterized by chemical analysis, N2 adsorption/desorption at 77 K, X-ray diffraction ( XRD ), temperature-programmed reduction ( TPR ) and adsorption microcalorimetry of ammonia. Difference in the reducibility of the surface sites were found between the pure F2O3 an d the Na silicate containing catalysts. Doping by addition of V2O5, Sb2O5 or Cr2O3 did not lead to a significant modification of the reduction behaviour. On the contrary, the acidic properties of iron oxide were significantly affected by the presence of both Na silicate and V,Sb or Cr metal oxide. The addition of these minor components resulted in the improvement of the catalytic performance of the pure alfa-Fe2O3.
Toluene ammoxidation on alfa-Fe2O3-based catalysts
ROMBI, ELISABETTA;FERINO, ITALO;MONACI, ROBERTO;
2004-01-01
Abstract
The catalytic behaviour of alfa-Fe2O3- based catalysts in the toluene ammoxidation reaction was investigated in a continuous fixed-bed microreactor at 673 K, under atmospheric pressure. Catalysts were prepared and characterized by chemical analysis, N2 adsorption/desorption at 77 K, X-ray diffraction ( XRD ), temperature-programmed reduction ( TPR ) and adsorption microcalorimetry of ammonia. Difference in the reducibility of the surface sites were found between the pure F2O3 an d the Na silicate containing catalysts. Doping by addition of V2O5, Sb2O5 or Cr2O3 did not lead to a significant modification of the reduction behaviour. On the contrary, the acidic properties of iron oxide were significantly affected by the presence of both Na silicate and V,Sb or Cr metal oxide. The addition of these minor components resulted in the improvement of the catalytic performance of the pure alfa-Fe2O3.
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