Mechanism of N2O reduction by biomass gasification gas reburning

A molecular modeling based on the density functional theory (DFT) and the transition state theory (TST) was performed to investigate the influence of biomass gas CO on the N2O decomposition catalyzed by CaO during reburning in the circulating fluidized bed boiler. The model for N2O adsorption onto the CaO(100) surfaces were constructed; and the processes of the N2O decomposition on the CaO(100) surface and the surface recovery of CaO(100) were investigated. The results illustrate that the energy barrier of N2O decomposition on the CaO(100) surface is much lower than that in homogeneous case, and CaO is therefore able to catalyze the N2O decomposition. The atomic O from N2O decomposition can poison the active sites O atom on the CaO(100) surface, while biomass gas CO can promote the regeneration of the active sites on the surface of CaO(100), which is beneficial for CaO to catalyze the N2O removal.