SCR of Nitric Oxide by Hydrogen over Pd and Ir Based Catalysts with Different Supports

Abstract

Selective catalytic reduction of NO x with hydrogen (H 2 -SCR) in excess oxygen over Pd and Ir based catalysts with various silica supports was studied. The Pd/ V 2 O 5 /TiO 2 /SBA-15 and Ir/SBA-15 catalysts showed the highest activities. The effects of noble metal, various silica supports, CO and SO 2 on H 2 -SCR over these catalysts were also studied and compared, and possible underlying mechanisms discussed. A comparison of 1 % Ir-doped on silicas with a wide range of pore sizes showed that the peak temperature (where the NO conversion maximum was located) was directly related to the pore size: larger pores of the support resulted in higher peak temperatures. This result indicates that pore diffusion limitation played a role in determining the peak temperature. In addition, a nonnoble metal catalyst, Nb 2 O 5 /SiO 2 , was found to have considerable activity.Graphical Abstract Larger pores of the support resulted in higher peak temperatures, which indicated that pore diffusion limitation played a direct role.

Highly selective catalytic reduction of NO via SO2/H2O-tolerant spinel catalysts at low temperature

“…As shown in Fig. 7c, when the 100 ppm SO 2 was added to the reactant gas, the NO conversion of NiCo 2 O 4 at 350 °C decreased rapidly from 35.8 % to 31.6 % in 150 min and only recovered to 32.6 % after the removal of SO 2 , manifesting the inhibition effect of SO 2 on the SCR activity over NiCo 2 O 4 (Chang et al 2013; Yin et al 2015). When the SO 2 increased to 300 and 500 ppm, the NO conversion decreased rapidly to lower than 27.5 % and 14.5 % and only recovered to 30.6 % and 21.6 % after the removal of SO 2 , respectively.…”

“…At the same time, the SCR catalysts are sensitive to sulfur poisoning since sulfur compounds could deposit on the active sites of catalysts and deactivate them irreversibly (Chang et al 2013; Lee et al 2013; Yin et al 2015). Therefore, it was important to investigate the effect of H 2 O and SO 2 on NO conversion over selected catalysts.…”

110th Anniversary: Recent Progress and Future Challenges in Selective Catalytic Reduction of NO by H2in the Presence of O2

“…Apart from acidity/basicity and the redox property, the texture of support, such as pore size, plays an important role in the H 2 -SCR reaction. Yin et al 45 investigated Ir supported on silica supports with various pore sizes for the H 2 -SCR activity. It was found that the peak temperature at maximum NO x conversion depended on the pore size of supports.…”