The decomposition of Fe-substituted rhodochrosite during coaling enhanced the transformation of NO before catalyst bed: Effect of instant-calcination

Abstract

The NO conversion by Fe-substituted rhodochrosite before flue gas treatment systems in coaling plants needs further investigation. Hence the effect of Fe substitution on the conversion of rhodochrosite during coal combustion process conditions and the denitration efficiency of transformed products after NH3 injection were investigated. To simulate the reality of coaling process, Fe-substituted manganese oxide was obtained by instant heat treatment of Fe-substituted rhodochrosite. The manganese oxide obtained from the instant-calcined rhodochrosite had promising catalytic activity, the substitution of Fe slightly enhanced NO conversion efficiency at 100–200 ºC and 3 %Fe-850 exhibited the maximum NO conversion of 99.6 % at 150 ºC. Besides, the Fe doping enabled the thermal decomposition product of rhodochrosite to have higher porosity, lager surface area, more chemisorbed oxygen and acid sites, better redox capacity and greater relative content of Mn4+. Furthermore, in-situ DRIFTs experiment demonstrated Fe doping increased the number of acid site and promoted the formation of intermediates (-NH2) and monodentate nitrite, which will benefit catalytic activity. Moreover, E-R mechanism was dominant in the reaction at different temperatures. This work improves our understanding of the de-NOx behavior following NH3 injection during coaling.