The modifications of 2 oxides with Sb/Fe ratios of 1 and 2 during calcination at <1000° and after catalytic tests (1-butene oxidn. to butadiene) were studied by x-ray diffraction, IR, and Moessbauer analyses. A nonstoichiometric (NS) rutile structure with excess Sb held within the structure itself is formed on both catalysts calcined at ≤900°. The strong increase both in selectivity and activity in allylic oxidn. shown by the catalyst with an Sb/Fe ratio of 2 is attributed to the formation of a NS-rutile that is stable during catalytic tests. The excess Sb held within the structure creates Sb:O double bonds which are responsible for the increase of selectivity and activity. The fundamental role of the method of prepn. by copptn. in a basic medium is also suggested. [on SciFinder(R)]
The role of excess antimony as a promoter of activity and selectivity in selective oxidation in the iron-antimony system
CENTI, Gabriele;
1985-01-01
Abstract
The modifications of 2 oxides with Sb/Fe ratios of 1 and 2 during calcination at <1000° and after catalytic tests (1-butene oxidn. to butadiene) were studied by x-ray diffraction, IR, and Moessbauer analyses. A nonstoichiometric (NS) rutile structure with excess Sb held within the structure itself is formed on both catalysts calcined at ≤900°. The strong increase both in selectivity and activity in allylic oxidn. shown by the catalyst with an Sb/Fe ratio of 2 is attributed to the formation of a NS-rutile that is stable during catalytic tests. The excess Sb held within the structure creates Sb:O double bonds which are responsible for the increase of selectivity and activity. The fundamental role of the method of prepn. by copptn. in a basic medium is also suggested. [on SciFinder(R)]Pubblicazioni consigliate
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