Behaviors of bio-modified calcium-based sorbents for simultaneous CO2/NO removal: Correlation of the characteristics of biomass, modified Ca-sorbent and reactivity.

Simultaneous CO₂/NO removal from flue gas is extensively attracted to meet the goal of atmospheric pollutant and carbon mitigations. An optimized CaO-CO system via the design of the bio-modified calcium-based pellet is proposed in which the pyrolysis of biomass ensures efficient CO₂/NO removal. Since the type of biomass shows great influence on the characteristics of pyrolysis products which may influence the behavior of reaction, the correlations of characteristics of biomass structural components, modified Ca-sorbent, and CO₂/NO removal reactivity were established with the support of experimental results and Density functional theory (DFT) calculation. The results reveal that the high content of cellulose in biomass plays a role in improving the microstructure of the bio-modified Ca-pellet (favor carbonation and CaO-catalyzed CO-NO), while the high content of lignin corresponds to the generation of more biochar in the sorbent (favor CO-promoted Char-NO). The leading role of CO-NO or Char-NO displays varied importance with the changing pore structure and biochar amount in the Ca-pellet. This work reveals the prospect of selecting the properties of biological additives to prepare effective calcium-based sorbents to improve CO₂/NO co-capture performance.