Long Time Molecular Dynamics Simulation of Nitrogen Migration During Oxygen-Lean Oxidation of Lignite

Abstract

ReaxFF MD simulations over 2250 picoseconds were performed to investigate the nitrogen migration in the oxygen-lean oxidation of Wulfum lignite model. The results show that, with the increase of excess air coefficient, O2 attacks the nitrogenous groups more severely, and the total yields of HNO and NCO generated in the subsequent decomposition reactions increase. HCN can be directly oxidized into NCO, or converted first into HCNO and then into NCO. A lot of NO comes from the conversion of HNO and NCO. NO can be directly reduced to N2 or to NCO by NCO or CO. NCO can react with NH or HO-NH to form N2H or N2, and N2H can decompose or react with OH to form N2. A lot of NCO is adsorbed, reduced or transformed into tar nitrogen, which is a major reason for NO reduction.