Selective catalytic oxidation of ammonia to nitrogen over orderly mesoporous CuFe2O4 with high specific surface area

Abstract

Orderly mesoporous CuFe2O4 spinel-type mixed oxide with high specific surface area was prepared successfully by a hard-template method in which KIT-6 mesoporous silica was selected as the hard template. The KIT-6 hard template and CuFe2O4 samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray fluorescence, transmission electron microscopy, scanning electron microscopy, nitrogen physisorption, and hydrogen-temperature programmed reduction. The KIT-6 hard template had perfect crystallization and ordered mesoporous structure with a probable pore distribution of about 9.1 nm, large enough to be filled by the spinel precursor. The mesoporous CuFe2O4 spinel oxide synthesized inside the KIT-6 mesopores had a relatively small pore size (4.3 nm), orderly arrangement, and high specific area (194 m2/g). The catalytic activity of the mesoporous CuFe2O4 was tested for the selective oxidation of ammonia to nitrogen. The conversion of ammonia reached nearly 100 % at 300 °C with a nitrogen selectivity as high as 96 %. The nitrogen selectivity remained high with increasing temperature and even maintained a value of 80 % at 600 °C.