Effect of SO 2 on Catalytic Performance of CoH-FBZ for Selective Catalytic Reduction of NO by CH 4 in The Presence of O 2

Abstract

The effect of SO₂ on the catalytic performance of CoH–FBZ (FBZ is composite zeolite with FAU and BEA topology) and CoH–Beta for selective catalytic reduction of NO by CH₄ (CH₄ –SCR) were studied with SO₂ temperature-programmed surface reaction (TPSR) and NO + (O₂) adsorption and temperature-programmed desorption (TPD) techniques. The CH₄ –SCR activity results showed that the change in topology of the zeolite had a strong impact on effect of SO₂. In the same reaction conditions, CH₄ –SCR activity decreased less over CoH–FBZ than over CoH–Beta due to the addition of SO₂ , regardless of the presence or absence of H₂O. Addition of 78 ppm SO₂ decreased the NO to N₂ conversion from 85% to a stable level at 70% over CoH–FBZ, while from 71% to a stable level at 51% over CoH–Beta at 773 K. Comparing with fresh catalysts, after poisoning reaction in 673–823 K, a decrease of capacity for NO + O₂ adsorption over SO₂ -exposed CoH–FBZ was less than that over SO₂ -exposed CoH–Beta. CoH–FBZ exhibited better SO₂ tolerance than CoH–Beta due to the less stable adsorption of sulfur species over CoH–FBZ than over CoH–Beta, as revealed by SO₂ –TPSR.