Single-atom Ir
1 supported on rutile TiO
2 for excellent selective catalytic oxidation of ammonia.
JOURNAL OF HAZARDOUS MATERIALS 2022;
432:128670. [PMID:
35290894 DOI:
10.1016/j.jhazmat.2022.128670]
[Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/24/2022] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Abstract
Gaseous ammonia (NH3) in the atmosphere is potentially harmful to both human health and the environment. The selective catalytic oxidation of NH3 (termed as NH3-SCO) into N2 and H2O is a promising method for decreasing NH3 emissions. A highly efficient catalyst is required for controlling NH3 emissions by this method in practice. In this study, we prepared Ir/TiO2 catalysts using different crystal structures of TiO2 (rutile, P25 or anatase) as supports by a simple impregnation method and evaluated their performance in the NH3-SCO. We found that the Ir/TiO2-R (rutile) catalyst performed better than the Ir/TiO2-P25 (mixed-phase) and Ir/TiO2-A (anatase) catalyst. High-angle annular dark-field images of the aberration-corrected scanning transmission electron microscopy revealed that the Ir species were mainly atomically dispersed on the TiO2 support in Ir/TiO2-R with 1 wt% Ir loading, whereas the Ir species agglomerated to form clusters or nanoparticles in Ir/TiO2-P25 and Ir/TiO2-A. The combined results of X-ray absorption fine structure, H2-temperature-programmed reduction, and in situ diffuse reflectance for infrared Fourier Transform spectroscopy studies suggested that atomically dispersed Ir species had stronger electronic metal-support interaction with rutile TiO2, which resulted in easier to adsorb and activate O2 at the interface and thus, better low-temperature activity of the Ir/TiO2-R catalyst.
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