Effect of H₂ on deNO_x performance of HC-SCR over Ag/Al₂O₃: Morphological, chemical, and kinetic changes

The enhanced deNOx performance of the Ag/Al2O 3 catalyst by addition of H2 was investigated for HC-SCR using a mixture of simulated diesel and ethanol as the reductant. As H 2 concentration increased in the feed-gas stream, the low-temperature NOx reduction activity was remarkably enhanced. Addition of H 2 promoted the oxidation of both NO and hydrocarbons, resulting in an increased formation of nitrates, enolic, and isocyanate species regarded as reaction intermediates. Results of the UV-vis indicated that H2 promoted the transformation of Ag+ to Agnδ+ and Ag0 on the surface of Ag/Al2O3 catalyst, while those of H 2-TPR, O2-TPD, in situ FTIR, and TGA revealed the formation of highly mobile and reactive oxygen species under the (O2 + H2) flow. A reaction mechanism is proposed to elucidate the role of H2 in the enhancement of deNOx performance of HC-SCR in view of morphological, chemical, and kinetic changes of the Ag/Al 2O3 catalytic system. © 2013 Elsevier Inc. All rights reserved.

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Author Seog Oh Physics