De-NOx characteristics of HC-SCR system employing combined Ag/Al2O3 and CuSn/ZSM-5 catalyst

The combination of Ag/Al2O3 and CuSn/ZSM-5 on catalytic performance was investigated for selective catalytic reduction of NOx by H-2-assisted C3H6. The Ag loading significantly affected the de-NOx performance and C3H6 conversion; a low Ag loading in the catalyst (less than 2 wt% Ag) afforded superior de-NOx performance compared to that obtained with more than 4 wt% Ag, owing to the lack of agglomeration of Ag particles on the support (Ag/Al2O3) in the former. Considering the C3H6 slip, a very high reaction temperature (above 525 degrees C) was required for complete C3H6 oxidation. A combination of Ag/ Al2O3 and CuSn/ZSM-5 allowed complete C3H6 oxidation below 350 degrees C owing to the superior C3H6 oxidation ability of CuSn/ZSM-5, which is the merit of the combined system compared with Ag/Al2O3 or CuSn/ZSM-5 used individually. The best catalytic configuration is the sequential arrangement of 1Ag/Al2O3 + 2Cu1Sn/ZSM-5, which could simultaneously reduce NOx, C3H6, and H-2 over a wider temperature window ranging from 300-600 degrees C. Notably, the reduced NOx was almost entirely reduced to N-2 with negligible generation of N2O, NH3, and HCNO. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The combination of Ag/Al2O3 and CuSn/ZSM-5 showed superior catalytic performance in reducing NOx and oxidizing C3H6 at lower temperatures. Sequential arrangement of 1Ag/Al2O3 + 2Cu1Sn/ZSM-5 was found to be the best catalytic configuration for simultaneous reduction of NOx, C3H6, and H-2 over a wide temperature range. The reduced NOx was mostly converted to N-2 with minimal generation of N2O, NH3, and HCNO.