Composite Solid Absorbent for Simultaneous Desulfurization and Denitrification of Low-Temperature Flue Gas

Abstract

ABSTRACT The composite solid absorbent was developed for simultaneous desulfurization and denitrification of low-temperature flue gas. The efficiency of this absorbent was confirmed by a pilot experiment in a coke oven. The surface and cross-section morphologies, elemental compositions and distributions, specific surface areas and pore size distributions, and phase compositions of fresh and used absorbents were measured to investigate the enhanced performance mechanism of absorbent and its removal mechanism for SO2 and NOx. The results showed that the absorbent had an efficient desulfurization and denitrification performance with about 99.9% SO2 removal and more than 80% NOx removal. The narrow pore distribution of absorbent produced more specific surface area as well as more active sites, which significantly enhanced the reactive activity of the absorbent greatly. Furthermore, the nanometer-scale channels and pores on the surface of absorbent promoted the diffusion of flue gas and the reaction of absorbent. SO2 reacted with residual O2 to produce SO3, which formed CaSO4 in the absorbent ultimately. NO reacted with residual O2 and CO to form N2 under the action of absorbent, which could be promoted at low temperature. For the CO-uncontained flue gas, NO will be removed by reacting with residual O2 and the absorbent to produce Ca(NO3)2, which is beneficial for the solidified absorption of SO2.