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

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 NO_x. The results showed that the absorbent had an efficient desulfurization and denitrification performance with about 99.9% SO₂ removal and more than 80% NO_x 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.

KEYWORDS:

• Composite solid absorbent
• simultaneous desulfurization and denitrification
• low-temperature flue gas
• enhanced performance mechanism
• unreacted core model
• removal mechanism

Additional information

Funding

This research work was partially supported by the National Natural Science Foundation of China [Grant Nos. 51974022, U1560101].