Combination DFT and Molecular Dynamics Study on Noncatalytic Reduction of Nitrogen Oxide by Furan during Cocombustion with Biomass: Soot Inhibition and Nitrogen Evolution.

Using biotar as a reburning fuel is a potential method for NO reduction. Furan, a typical biomass tar compound, is used to study NO reduction during cocombustion with biomass. The combination density functional theory (DFT) and ReaxFF molecular dynamics (MD) methods were used to study the detailed mechanism at the molecular level. ReaxFF MD simulation results indicate that significant decomposition of furan occurs at temperatures above 2000 K, releasing small molecular products such as CO. At 3000 K, the decomposition process is accompanied by polymerization reactions, leading to the formation of substantial amounts of soot. The reaction results of the NO and furan mixture system indicate that the presence of NO inhibits the formation of soot during furan decomposition. Conversely, furan plays a significant role in promoting the reduction of NO. Furan undergoes significant conversion at lower temperatures, suggesting that NO can directly oxidize furan molecules. HNO is recognized as a key intermediate. DFT calculations reveal that the activation energy required for the direct oxidation of furan by NO is 228.2 kJ/mol, which is much lower than that for the direct decomposition of furan, which is 311.13 kJ/mol. The research results theoretically demonstrate the feasibility of using furan-type biomass tar as a reburning fuel for NO reduction. This holds significant importance for biomass gasification coupled with coal-fired technology.