The uniform antimony-rich surface layer on Fe
2O
3 was carried out via thermal spreading of Sb
2O
3 and Sb
2O
4. TG–DTA results indicate that the oxidation temperature of Sb
2O
3 was decreased ca. 100 K due to thermal spreading effect. Although Sb
2O
4 is almost catalytically inert for oxidation of isobutane and Fe
2O
3 is a typical non-selective catalyst for this reaction, the formation of antimony-rich layer suppresses the combustion reactions and favors the partial oxidation reactions. When Sb
2O
4 instead of Sb
2O
3 was used as antimony resource, the enrichment of antimony on Fe
2O
3 surface was much lower. However, the reaction atmosphere of isobutane oxidation enhances antimony spreading over Fe
2O
3 surface. According to Mars–Van Krevelen mechanism, some Sb
2O
4 in catalysts could be intermediately reduced into Sb
2O
3 during reaction of isobutene oxidation, which thermal spreading is much easier. As shown by Raman results, the Sb
2O
4 that has been spread on Fe
2O
3 surface is probably amorphous.
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